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Biomedical subjects

Y Manabe

Publications and source records attributed to Y Manabe.

At least 91 records · Page 5Linked to original sources
PubMed1997

Effects of lidocaine on salicylate-induced discharge of neurons in the inferior colliculus of the guinea pig.

Using the extracellular recording method, the effects of lidocaine (a local anesthetic known to relieve tinnitus) on discharge of inferior colliculus (IC) neurons of the guinea pig were studied before and after salicylate (200 mg/kg) administration. The salicylate-induced discharge was inhibited by intravenous injection of lidocaine at a concentration (1 mg/kg) clinically used for treating tinnitus. IC neurons could be classified into two groups according to the difference in sensitivity to lidocaine: (1) weakly-sensitive neurons and (2) highly-sensitive neurons. In weakly-sensitive neurons, the duration of the lidocaine effect lasted for less than 5 min, and the inhibitory action on the discharge of neurons was greater when the latency to sound stimulus became longer. In highly-sensitive neurons, on the other hand, the activity of neurons was almost completely inhibited for longer than 30 min, irrespective of the latency to sound stimulus. The clinical relevance of these types of neurons is discussed.

Action Potentials↗
PubMed1997

Synthesis and antimicrobial characteristics of 4,4'-(alpha,omega-polymethylenedithio)bis(1-alkylpyridinium iodide)s.

Bis-quaternary ammonium compounds (bis-QACs), 4,4'-(alpha,omega-polymethylenedithio)bis(1-alkylpyridinium iodide)s (4DTBP-m,n), which have 3 to 10 carbon atoms in the connecting methylene chain (m) and 8 to 18 carbon atoms of the N-alkyl chain (n), were synthesized. 4DTBP-6,12 exhibited a wide antimicrobial spectrum against gram-positive and gram-negative bacteria and fungi. The activity was stronger than those of N-dodecylpyridinium iodide (P-12), benzyldodecyldimethylammonium chloride and 2-(4-thiazolyl)benzimidazole. The bactericidal activities of 4DTBP-m,n were scarcely affected by the lengths of the alkyl chain and methylene chain. The bis-QAC that showed the highest activity was 4DTBP-6,8 (minimum inhibitory concentration (MIC) = 1.6 microM, minimum bactericidal concentration (MBC) = 2.6 microM), and its activity was about 10 times that of N-hexadecylpyridinium iodide (P-16), which was the most active in the P-n series. In addition, 4DTBP-6,12 showed a high bactericidal activity in the ranges of pH 5 to 8.5 and 10 to 40 degrees C, in contrast to mono-QACs. The bis-QACs synthesized in this study have excellent bactericidal properties.

Anti-Bacterial Agents↗
PubMed1997

The internal orbital facial breadth and middle facial breadth in Mongoloid crania from Peru and east Asia, with special reference to their significance as a racial criterion.

The internal orbital facial breadth (BIFMO), middle facial breadth (BIZM) and their dimensional relationship in 789 crania from 3 Peruvian and 7 East Asian series were examined to determine a Mongoloid criterion. The results confirmed that BIZM was invariably greater than BIFMO in the Peruvian and East Asian series, and clearly different from the quoted European and African populations (Ducros, 1965). Further discussion, which referred to world population data by Woo and Morant (1934), showed that the relationship between BIZM and BIFMO was useful as a simple racial criterion to distinguish the Mongoloid series, except in special cases such as the Oceanians.

Adult↗
PubMed1997

[A case of idiopathic orthostatic hypotension with selective involvement of postganglionic noradrenergic neurons].

A 44-year-old man had a 30-year history of orthostatic hypotension and diarrhea. One month before admission, he suddenly lost consciousness by defecation, and was hospitalized. He became alert within two days, but he could not sit up due to severe orthostatic hypotension. At that point, he was transferred to our hospital. On admission, talipes and microdactylia were noted. Neurological examination revealed brisk patellar tendon reflexes. Anhidrosis or impotence was not present. Analyses of blood and urine yielded normal results. Cardiological examination revealed no abnormality that could be responsible for the hypotension. MR images of the brain were also normal. However, single photon emission tomography revealed diffuse hypoperfusion of the brain. A head-up tilt (50 degrees) test induced a remarkable fall in systolic blood pressure from 149 (heart rate; 65/min) to 64 mmHg (83). Immersion of hand in ice-cold water failed to increase blood pressure. Heart rate variation and cystometry results, which represent the function of parasympathetic nerves, were normal. Warming of his body caused normal sweating. Intravenous injection of low doses of norepinephrine and methoxamine increased blood pressure while isoproterenol remarkably increased heart rate, suggesting that both alpha- and beta-receptors developed supersensitivity. Instillation of 5% cocaine and 5% tyramine into the conjunctival sac failed to cause pupillary dilation. Clinical findings and pharmacological challenge test results suggested that the main lesion of his autonomic nervous system was selectively confined to the postganglionic sympathetic nerves and noradrenergic (not cholinergic) neurons. The autonomic failure of our patient can be classified as idiopathic orthostatic hypotension. However, most patients with idiopathic orthostatic hypotension or pure autonomic failure complain of anhidrosis and impotence, which were not noted in our patient. These symptomatic differences may be the result of the highly selective involvement of noradrenergic neurons in the postganglionic sympathetic system in our patient.

Adult↗
PubMed1996

Morphological and anthropological aspects of human triangular deciduous lower first molar teeth.

The crown and root morphology, and bilateral occurrence of human deciduous lower first molars that exhibited a triangular occlusal outline, taken from excavated samples of Japanese, Jomonese and Iraqi origin, were investigated. The crowns of triangular teeth had smaller mesiodistal and larger buccolingual diameters than normally shaped deciduous lower first molars. An elongated buccolingual diameter was derived from the buccal projection of the distobuccal cusp and lingual projection of the portion between the metaconid and distolingual cusp. In this analysis, all triangular deciduous lower first molars in which root morphology could be observed were accompanied by additional distolingual roots. Correlation between the right- and left-hand sides of this trait was high.

History, 15th Century↗
PubMed1996

Synergistic effect between size and cholesterol content in the enhanced hepatic uptake clearance of liposomes through complement activation in rats.

PURPOSE: The effect of liposome size and cholesterol (CH) content on the pharmacokinetics of liposomes was investigated in rats. METHODS: The pharmacokinetics of liposomes was examined using 5(6)-carboxyfluorescein (CF) as an aqueous phase marker. The extent of complement activation (ECA) was also measured by the release of CF from liposomes in serum. RESULTS: Both the size and the CH content influenced the mean residence time, total body clearance, and the hepatic uptake clearance (CLh) of liposomes. The increase of the size of liposomes increased the CLh at each CH content. There was no CH dependency of CLh in small liposomes (200 nm in diameter), although the CLh increased with the increase in the CH content in large (800 nm) and medium (400 nm) liposomes. A significant interaction effect was observed between liposome size and the CH content on CLh according to the analysis of variance. The good correlation between CLh and ECA indicated the role of complements as opsonins in enhancing the hepatic uptake of liposomes. The interaction effect between the size and CH content on CLh was explained principally by the product of the size and CH content. CONCLUSIONS: A synergistic effect was observed between the size and the CH content on CLh. An underlying hypothesis of the synergistic effect was postulated based on the size dependent recognition of liposomes by complement system.

Analysis of Variance↗
PubMed1996

Cisplatin metabolites and their toxicity on isolated cochlear outer hair cells in vitro.

The exact mechanism of ototoxicity by cisplatin remains obscure. In the present study, the toxicity of cisplatin metabolites was evaluated using isolated outer hair cells of guinea pig cochlea. Cisplatin metabolites were produced by reaction of cisplatin and S9 fraction from guinea pig liver after administration with phenobarbital. The viability of the outer hair cells did not decrease after the incubation in non-metabolized cisplatin solutions or S9 fraction only, demonstrating the absence of toxic effect from non-metabolized cisplatin and the absence of intrinsic toxic substances in S9 fraction. However, metabolized cisplatin reacted with S9 fraction at 37 degrees C significantly decreased the viability. Cisplatin reacted with heat-treated S9 fraction did not produce a cytotoxic effect, suggesting an enzymatic basis for the formation of metabolites. When NADP was omitted, outer hair cells remained viable, suggesting the significant role of oxygenases in the metabolism of cisplatin. The existence of a toxic metabolites could account for the poor correlation between drug peak level and pathologic damage to the inner ear, and a delay in the onset of ototoxicity could represent the time necessary for induction of the metabolizing enzymes or for reaching a critical point in toxicity by metabolites.

Animals↗
PubMed1995

Transplatin blocks voltage-dependent calcium current in isolated cochlear outer hair cells but is not ototoxic in vivo.

The effects of cisplatin (cis-DDP) and transplatin (trans-DDP) on the voltage-dependent calcium current (ICa) of outer hair cells isolated from the guinea pig cochlea were compared using the whole-cell patch-clamp technique. Both cis-DDP and trans-DDP blocked ICa in a concentration-dependent manner. Trans-DDP did not show ototoxicity or nephrotoxicity in vivo. From these results, it was suggested that the effect of cis-DDP on ICa does not directly lead to cell death.

Animals↗
PubMed1995

Deciduous dental morphology of the prehistoric Jomon people of Japan: comparison of nonmetric characters.

Morphological variations of the deciduous dentition are as useful as those of the permanent dentition for determining the biological affinities of human populations. This paper provides material on morphological variations of deciduous teeth of the prehistoric Japanese population from the Late and the Latest Jomon Period (ca. 2000-ca. 300 B.C.). The expression of nonmetric traits of the deciduous teeth in the Jomon sample shows a closer affinity with modern Japanese and Native American samples than with American White, Asiatic Indian, and African samples. However, the frequency of shoveling in deciduous upper incisors in the Jomon sample is lower than those in modern Japanese and Native American samples. The Jomon sample also expresses a much higher frequency of cusp 6 in deciduous lower second molars than seen in modern Japanese, Ainu, and Native American samples. The frequency in the Jomon sample is equal to that in the Australian Aboriginal sample, which shows cusp 6 most frequently among the samples compared. A somewhat low incidence of incisor shoveling in the Jomon sample was also reported in the permanent dentition (Turner [1976] Science 193:911-913, [1979] Am. J. Phys. Anthropol. 51:619-635, [1987] Am. J. Phys. Anthropol. 73:305-321, [1990] Am. J. Phys. Anthropol. 82:295-317; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:163-182, 88:183-196). However, the frequency of cusp 6 in the Jomon sample shows no significant difference from those of Northeast Asian or Native American samples in the permanent dentition (Turner [1987] Am. J. Phys. Anthropol. 73:305-321; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:163-182, 88:183-196). Evidently, some nonmetric traits express an inter-group difference only in the deciduous dentition.

Africa, Southern↗
PubMed1995

A study on urine cotinine for the evaluation of smoking cessation.

Two branch offices of enterprise T in the same city engaged in service and sales were selected at random for this study on the evaluation of smoking cessation education using the urine cotinine concentration (U-Cot) measured by ion pair reversed-phase high performance liquid chromatography (IP-R-HPLC). Branch A conducted a smoking cessation education program; branch B did not. By comparison of the results obtained from questionnaires and U-Cot analyses at both the offices, we investigated the validity of evaluation by U-Cot. The results were as follows: I. Smokers 1. At branch A, a self-reported 20-year-old female non-smoker was confirmed to smoke about 5 cigarettes per day by her high concentration (292.8) of U-Cot at pre-education. 2. At branch A, the self-reported average number of cigarettes smoked daily (ANCSD) at 6 months post-education showed a significant decrease in comparison with that at pre-education. 3. At branch A, U-Cot at post-education showed a significant decrease in comparison with those at 2 weeks, 2 months, and 6 months pre-education in descending order. 4. Two male subjects who were strongly suspected to have submitted a false number of cigarettes smoked prior to urine sampling (NCSPU)/ANCSD self-reports at 6 months post-education were confirmed to have done so by the U-Cot values at the fourth period, which were in excess of 500, and the discrepancy between the ratio ([value at post-education in 6 months] divided by [value at pre-education]) of U-Cot (1.52, 1.47, respectively) and that of NCSPU/ANCSD, (0.00)/0.00). 5. At branch A, discrepancies between the success rate of quitting smoking in self-reported NCSPU/ANCSD at 6 months (17.0%) and in U-Cot (12.2%) were observed. At branch B, no such discrepancies were observed. 6. At branch A, office workers at 6 months post-education who had, but not those who had not, previously considered the health damage caused by smoking showed a significant decrease in NCSPU/ANCSD, and also in U-Cot at 2 weeks, 2 months and 6 months post-education. At branch B, no such differences were observed. 7. At branch A, office workers at 6 months post-education who had previously considered quitting smoking showed a significant decrease in NCSPU/ANCSD, and also in U-Cot at 2 weeks, 2 months and 6 months post-education. Those who had not previously considered quitting showed a significant decrease in ANCSD, but not in NCSPU or U-Cot.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Vestibular dysfunction in noise induced hearing loss.

It is known that loud tones can damage the cochlea, but vestibular involvement has been given less attention. However, patients with noise induced hearing loss (NIHL) sometimes have balance disorders as well as some have symptoms resembling those of Meniere's disease. In this study, we examined the relationship between loud sounds and vestibular problems. Thirty-six NIHL patients were divided into two groups according to the presence (vertigo group) or absence (non-vertigo group) of vestibular complaints. Electrocochleograms were recorded from all subjects after pure tone audiometry. A higher incidence of increased -summating potential (SP)/action potential (AP) ratio was observed in the vertigo group than in the non-vertigo group. Caloric tests were performed in the vertigo group, and a reduced response was observed in 47.1% of ears. It is generally considered that the -SP/AP ratio is a useful indicator of endolymphatic hydrops. Therefore, episodic vertigo in NIHL patients may result from a pathophysiological mechanism similar to that of Meniere's disease.

Caloric Tests↗
PubMed1995

Semiquantitative analysis by scanning electron microscopy of cochlear hair cell damage by ototoxic drugs.

The ototoxicity of cisplatin and carboplatin in the organ of Corti of the guinea pig was evaluated semiquantitatively. Damage of the stereocilia of outer hair cells (OHCs) observed by scanning electron microscopy (SEM) was classified into normal, grade 1 (10-50% loss of stereocilia), grade 2 (less than 50% remaining stereocilia), or grade 3 (missing stereocilia). The OHCs observed by light microscopy (LM) were classified as remaining or missing cells. Fifty OHCs of each row in the middle part of each turn of the cochlea were counted (a total of 150 cells per turn). Guinea pigs were administered 5 mg/kg of cisplatin or 50 mg/kg of carboplatin intraperitoneally for three consecutive days. In groups 1 and 2, in which both cochlea were fixed in 2.5% glutaraldehyde and 1% osmium tetroxide (OsO4) and observed by SEM, the percentages of damage of the OHC stereocilia were similar in each cochlear turn bilaterally. In group 3, the right cochleae were fixed in OsO4 and observed by phase contrast microscopy as surface preparations. Left cochleae were submitted for SEM observation. Missing and grade 3 cells were observed at similar percentages in each row of each turn. In group 4, succinate dehydrogenase staining was performed in the right cochleae and observed by LM. The degree of damage in the right cochleae was compared with that of the left cochleae which was observed by SEM. On average, the mean numbers of missing cells and cells showing grade 3 damage were similar in each row of each turn. From these similarities of evaluation of ototoxicity at LM and SEM levels, it was concluded that semiquantitative analysis by SEM only is appropriate for the assessment of ototoxicity.

Animals↗
PubMed1994

Effect of topical administration of L-arginine on formalin-induced nociception in the mouse: a dual role of peripherally formed NO in pain modulation.

1. We investigated the effects of intraplantar (i.pl.) administration of L-arginine and NG-nitro-L-arginine methyl ester (L-NAME) on formalin-induced behavioural nociception in the mouse. 2. L- but not D-arginine, at 0.1-1 microgram per paw, coadministered with i.pl. formalin, enhanced the second-but not the first-phase nociceptive responses, whereas it was without significant effects at 3 micrograms per paw, and conversely, produced antinociception at 10 micrograms per paw, resulting in a bell-shaped dose-response curve. 3. L-NAME at 0.1-1 microgram per paw, when administered i.pl., exhibited antinociceptive activity in the second phase in a dose-dependent manner, although its D-enantiomer produced no effect. 4. An antinociceptive dose (1 microgram per paw) of L-NAME (i.pl.) considerably reduced the increase in second-phase nociception elicited by low doses (1 microgram per paw) of i.pl. L-arginine. The second-phase nociception decrease induced by a large dose (10 micrograms per paw) of i.pl. L-arginine was markedly reversed by i.pl. L-NAME at 0.1 micrograms per paw, raising it to a level above that of the control (formalin only). 5. These results suggest that peripheral NO plays a dual role in nociceptive modulation, depending on the tissue level, inducing either nociceptive or antinociceptive responses.

Administration, Topical↗