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Biomedical subjects

H Nagasaki

Publications and source records attributed to H Nagasaki.

8 recordsLinked to original sources
PubMed1978

Disturbances of rhythm formation in patients with Parkinson's disease: part I. Characteristics of tapping response to the periodic signals.

A tapping test in which the tasks required a synchronous response to a periodic sound signal by the finger tapping was performed by 27 normal subjects and 146 patients with Parkinson's disease. Some patients could not maintain a synchronous response at a critical frequency of 2.5 or 5 Hz (taps per second) and showed a hastened tapping of 5 6 Hz, independent of the input signal frequencies, i.e., the 'hastening phenomenon.' The other patients and normal subjects could respond synchronously up to 5 7 Hz. Autocorrelational analysis of the sequential tapping intervals suggested that the synchronized response was performed by a feedback control with the input signal as target except at 2.5 and 5 Hz, whereas the hastened tapping of patients was a random process. The frequency-dependence of the error in the tapping was interpreted as representing an intrinsic oscillation in the central nervous system, which would be masked in normal subjects but released in patients with Parkinson's disease. Around 2.5 or 5 Hz the error or response becomes so large that some patients can no longer maintain the synchronized response and show a hastened tapping due to this intrinsic oscillation.

Acoustic Stimulation↗
PubMed1978

Disturbances of rhythm formation in patients with Parkinson's disease: part II. a forced oscillation model.

The origin of the characteristic disturbances of rhythm formation in patients with Parkinson's disease (the hastening phenomenon) was discussed, using a second-order system of the periodic response. The input signal was regarded as a pulse series of a Dirac function. The output process of the system had maximal errors of response at input frequencies of f = omega0/n (n = 1, 2, . . .), where omega0 was the intrinsic frequency of the system. Damping coefficient epsilon represented a function of an inhibitor against these maximal errors and the errors diverged to infinity when epsilon = 0. The solution of this forced oscillation system indicated that the intrinsic oscillation of the system has a possibility to be excited at these critical frequencies f = omega/n. Inferred from data on the tapping test, the frequency of an intrinsic oscillation was 5 Hz in the central nervous system, then the critical frequencies were predicted 5/n = 5, 2.5, . . . Hz. On the tapping test the errors of response become maximum around 2.5 and 5 Hz (taps per second), and their peak heights increased from the minimum in well trained normal subjects to the maximum in patients. An inhibitory mechanism against the maximal error would function well, i.e. epsilon greater than 0, in normal subjects but so insufficiently (epsilon leads to 0) in patients that the excited intrinsic oscillation would control their response directly. Thus some patients could no longer maintain a synchronous tapping response at 2.5 Hz or 5 Hz and showed a hastened tapping of 5 6 Hz independent of the signal frequency.

Central Nervous System↗
PubMed1976

Simple and stable techniques for recording slow-wave sleep.

1. A combination technique of a telemetric system and a Walter-type analyzer have been used in the rat to allow on-line display of the sleep-waking cycle of a freely-moving animal on three consecutive days. 2. The characteristics of slow-wave sleep can be analyzed completely by this technique. 3. Telemetric recording of the integrated slow wave is a good method that allows faster and accurate scoring of slow waves to measure the length of sleep in freely-moving animals.

Animals↗
PubMed1975

Development of hepatocellular carcinomas in rats treated with benzene hexachloride.

The effects of prolonged oral administration of the alpha-, beta-, and gamma-isomers of benzene hexachloride (BHC) on rat liver were examined histologically. Well-differentiated hepatocellular carcinomas were observed in the liver of rats fed a basal diet containing 1,500 or 1,000 parts per million (ppm) of alpha-BHC for 72 weeks. Many typical nodular hyperplasias developed in all groups given 1,500 or 1,000 ppm alpha-BHC. In non-neoplastic areas, slight oval cell infiltration and bile duct proliferation were seen. No neoplastic changes or other abnormal findings, such as oval cell infiltration, fatty changes, fibrosis, or bile duct proliferation of the liver, were observed in groups receiving 500 ppm alpha-, beta-, gamma-, or gamma-BHC.

Administration, Oral↗
PubMed1975

Effect of various factors on induction of liver tumors in animals by the alpha-isomer of benzene hexachloride.

The tumorigenic effect of a diet containing the alpha-isomer of benzene hexachloride (alpha-BHC) on the liver of various animals was examined. It was found that alpha-BHC induced liver tumors in male and female mice but not in rats or hamsters in the present observations. Histological changes in the liver of mice induced by alpha-BHC were also much greater than those induced in rats or hamsters. Male animals were more susceptible to the tumorigenic action of alpha-BHC than females. Among different strains of mice, the DDY showed greatest susceptibility and the C57BL/6 showed the least. Induction oflpha-BHC was not inhibited by concomitant feeding of 1-naphthyl isothiocyanate or p- hydroxypropiophenone. However, 3-methylcholanthrene slightly inhibited their induction by alpha-BHC.

Animals↗