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K Harasawa

Publications and source records attributed to K Harasawa.

7 recordsLinked to original sources
PubMed2000

Does the histaminergic system play a role in spinal nociception?

The author studied whether the histaminergic system is involved in spinal nociception or not. A nociception-related, slow ventral root potential of rats, which is an integrated output of motoneurons, was recorded as an index of the intensity of nociception when an electric stimulation was applied to the dorsal root. Histamine dissolved in an artificial cerebrospinal fluid caused small reduction in the potential; however, mepyramine (10 nM to 10 microM, as an H1 receptor antagonist), ranitidine (1 nM to 1 microM, as an H2 receptor antagonist), R(-)-alpha-methylhistamine (2 pM to 200 nM, as an H3 receptor agonist), and thioperamide (1 nM to 10 microM, as an H3 receptor antagonist) dose-dependently reduced the potential down to around a half of each control level. These results indicate that the histaminergic system may affect the spinal withdrawal reflex.

Animals↗
PubMed1997

Comparison of tympanic, esophageal and blood temperatures during mild hypothermic cardiopulmonary bypass: a study using an infrared emission detection tympanic thermometer.

OBJECTIVE: Tympanic temperature can be obtained instantaneously using an infrared emission detection (IRED) thermometer. Its accuracy has been documented in a variety of clinical settings, but its performance at low body temperatures is still unknown. In this study we evaluated its performance during coronary artery revascularization surgery in which mild hypothermic cardiopulmonary bypass (CPB) was used. METHODS: Thirty adult patients undergoing coronary artery bypass graft surgery were enrolled in the study. Tympanic temperature obtained using IRED thermometry (Tt1) was compared with core temperatures from the esophagus (Te), and venous blood of CPB (Tv) before, during, and after CPB. We also measured tympanic temperature using a thermocouple probe (Tt2) in 16 of the 30 patients in order to study the agreement between the two methods. Values for correlation coefficients and limits of agreement were computed to assess the degree of agreement among the temperatures obtained. RESULTS: The highest agreement with Tv during CPB was obtained from Tt1 (r = 0.94, 0.41 +/- 1.73, limits of agreement) and from Te (0.91, 0.36 +/- 2.46). Tt1 also showed good agreement with Tt2 during surgery. CONCLUSIONS: Infrared tympanic thermometry is a reliable, alternative method to measure tympanic temperature and may be useful to assess core temperature in both normothermic and mild hypothermic conditions.

Adult↗
PubMed1996

[Effects of halothane, isoflurane, enflurane, and sevoflurane on the monosynaptic reflex response in the isolated spinal cord of newborn rats].

Monosynaptic reflex responses (MSRs) in the isolated spinal cord of newborn rats were elicited in the ventral root by stimulation of the ipsilateral dorsal root. MSRs were considered to be mediated by non-NMDA class glutamate receptors. We studied the depressant effects of halothane, isoflurane, enflurane, and sevoflurane on MSR amplitudes as a function of anesthetic concentration comparing with MAC value of each anesthetics. The spinal cord of newborn rats were rapidly dissected out, and placed in a chamber superfused with artificial cerebrospinal fluid (ACSF, pH 7.4, 34 degrees C) equilibrated with 95% O2 - 5% CO2. Anesthetic gases were delivered with specific vaporizers and bubbled in the ACSF. Each anesthetic concentration was determined by gas chromatography. Either of the anesthetics reversibly depressed MSR amplitudes in a concentration dependent fashion. Concentration-response curves for MSR amplitudes were constructed and the concentrations which produced a half-maximum inhibition (IC50) were 0.56, 0.65, 0.97 and 1.18 mM for halothane, isoflurane, enflurane, and sevoflurane, respectively. These IC50 values correlated well with those of MAC values (r = 0.999, P < 0.001) obtained from adult rats in an in vivo condition. The MSR response in the isolated spinal cord of newborn rats is considered as a useful model for analysis of potency of volatile anesthetics.

Anesthetics, Inhalation↗
PubMed1994

Isolation and structure elucidation of the major photodegradation products of pirmenol hydrochloride.

Column chromatography, thin-layer chromatography, high-performance liquid chromatography, nuclear magnetic resonance spectrometry, and high-resolution mass spectrometry were employed to separate and identify the photodegradation products of pirmenol hydrochloride [(+/-)-cis-alpha-[3-(2,6-dimethyl-1-piperidinyl)propyl]-alpha-phenyl-2- pyridinemethanol monohydrochloride monohydrate], a new antiarrhythmic drug. A methanol solution of pirmenol was irradiated using a low-pressure mercury lamp. The solution afforded four major degradation products, three of which were identified as 3-(cis-2,6-dimethylpiperidinyl)propyl 2-(2-pyridyl)phenyl ketone, 2-(2-pyridyl)benzoic acid, and methyl 2-(2-pyridyl)-benzoate. The degradation followed apparent-first-order reaction kinetics. In addition, the possible photodegradation pathways are discussed with reference to reaction mechanisms.

Anti-Arrhythmia Agents↗
PubMed1993

Intralysosomal pH and release of lysosomal enzymes in the rat liver after exhaustive exercise.

The mechanism underlying exhaustive exercise-induced release of lysosomal enzymes was studied in the rat liver. Exhaustive exercise resulted in the release of beta-glucuronidase and cathepsin D, but not beta-glucosidase and acid phosphatase, into the blood and cytosol, suggesting that the release of lysosomal enzymes is not due to disruption of lysosomal membranes. The intralysosomal pH of the liver, which was approximately 5.5 at the resting level, rose significantly after exhaustive exercise to pH 6.3. In vitro, beta-glucuronidase and cathepsin D were released at an intralysosomal pH exceeding 6.2. In contrast, beta-glucosidase and acid phosphatase were not released. The elevation of intralysosomal pH reduced the aggregation of beta-glucuronidase and cathepsin D. The rate of ammonia accumulation increased markedly in the lysosome-enriched subcellular fraction after exercise. There was a positive relationship between the rate of ammonia accumulation and the elevation of intralysosomal pH in vitro. Lysosomes isolated after exhaustive exercise showed significantly increased osmotic fragility. Our findings suggest that, during exhaustive exercise, the accumulation of ammonia in lysosomes leads to the elevation of intralysosomal pH, resulting in the reduced aggregation of certain lysosomal enzymes. Thus, less aggregated lysosomal enzymes may be released into the cytosol through the lysosomal membrane, the permeability of which has been increased.

Acid Phosphatase↗
PubMedDate not supplied

The characteristics of static visual fields in children with psychogenic visual disturbances.

PURPOSE: It is well-known that patients with psychogenic visual disturbances (PVD) exhibit characteristic kinetic visual fields. Even when the kinetic fields are normalized, the static fields of PVD children frequently remain abnormal. To verify this finding, we performed static perimetry on those children whose kinetic fields were initially normal or which normalized during the follow-up period, and compared the results with those of children with psychosomatic disorders (PSD) and normal children. METHODS: We examined 9 PVD children (17 eyes), 16 PSD children (32 eyes), and 16 normal children (16 eyes). Program 30-2 or 24-2 of the Humphrey Field Analyzer was used in the examinations on all subjects. RESULTS: The average mean deviation (MD) of the PVD group was significantly lower than that of the other groups (P <. 01). False negative errors and short-term fluctuations were significantly higher in the PVD group than in the other groups (P <. 05). CONCLUSION: Although PVD and PSD children possess a similar underlying psychological dysfunction, their performances in visual field testing proved to be quite different. In the PVD group, even when kinetic fields were normal, functional visual field loss in the static fields was common and had characteristic response properties.

Child↗