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Biomedical subjects

M Ariizumi

Publications and source records attributed to M Ariizumi.

At least 37 records · Page 2Linked to original sources
PubMed1992

[Time-course changes of regional cerebral blood flow by SPECT with N-isopropyl-p-[123I]-iodoamphetamine in childhood partial seizures].

Single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]-iodoamphetamine was performed twice at different times in 18 children suffering from partial seizures to evaluate the time-course changes of the hemodynamics in the focal region. Comparison of the 2 SPECT images revealed that a decreased regional cerebral blood flow (CBF) in the first was normalized in 4 cases (22.2%) and contracted in 7 cases (38.9%). The region of decreased blood flow in the second was contralateral to that in the first in 1 case (5.6%) and unchanged in 6 cases (33.3%). Most of the normalized and contracted cases were those in which clinical seizures disappeared and the EEG findings were normalized. In these cases which responded to treatment, the decreased regional CBF was also found to be improved. Repeated SPECT appears to be useful for evaluating the therapeutic efficacy. On the other hand, most of the unchanged cases were those in which clinical seizures were frequent or uncontrolled, or which persistently showed the abnormalities in their EEG. SPECT was considered to reflect well the conditions of the epileptic foci. These results indicate that repeated SPECT for observing the time-course changes of the regional CBF represents a useful technique with can be applied in evaluating the therapeutic efficacy or deciding the time to discontinue treatment and for pathogenetic elucidation of the epileptic foci.

Adolescent↗
PubMed1991

Experimental studies on the effects of vibration and noise on sympathetic nerve activity in skin.

Multi-unit sympathetic activity was recorded at elbow level from median nerve fascicles supplying glabrous skin of the left hand in five healthy subjects. The resultant vasomotor responses accompanying the neural activity were monitored by simultaneous recordings of skin blood flow using the laser doppler method and skin temperature in the innervation zones. No significant change in sympathetic activity was observed during handgrip exercise of the right hand under a constant gripping force of 2 kg. Subjects maintained the same gripping force of the right hand during exposure in random order to local vibration and/or noise, each type of exposure lasting 5 min with intervals of 20 min. A two-peaked significant increase in outflow from sympathetic nerves was observed during local exposure of the right hand to vibration with a frequency of 60 Hz and an acceleration of 50 m.s-2, followed by a postexposure period which revealed a relative suppression of sympathetic nerve activity and a significant increase in blood flow. Noise at 100 dB(A) showed only an initial effect on skin sympathetic nerve activity (SSA), whereas when combined with local vibration at 60 Hz, a pronounced increase in neural activity was noticed, indicating a combined effect of vibration and noise. These results from direct recordings of SSA suggest a sympathetic vasomotor reflex mechanism triggered by local vibration stimuli to the hand.

Adult↗
PubMed1991

Effect of alcohol on blood levels of branched-chain alpha-keto acids in male Wistar rats.

The effect of oral alcohol administration on branched-chain alpha-keto acids was studied in Wistar rats. Rats were divided into alcohol loading groups 1 (ethanol single daily dose: 2.5 g/kg body wt for 14 days) and 2 (ethanol dose: 5 g/kg body wt), and a pair-fed control group (isocaloric glucose and food equal to the amount taken by group 1 the previous day). Branched-chain alpha-keto acids, other alpha-keto acids and amino acids were analysed using high-performance liquid chromatography. Results showed a significant body weight increase in the alcohol loading groups. Concentrations of branched-chain amino acids and keto acids were significantly increased in the alcohol-treated groups. The blood levels of methionine, threonine, alanine and glutamic acid were also increased by alcohol administration. Blood levels of taurine and ornithine, however, showed a significant decrease in the alcohol-treated groups. These results show that alcohol increases the blood levels of branched-chain keto acids and branched-chain amino acids.

Alcohol Drinking↗
PubMed1991

[Early diagnosis of neonatal neurological disorders].

Main diagnostic points on the clinical signs and symptoms of various neurological disorders during the neonatal period and early infancy are briefly mentioned. Application, diagnostic values and limitation of various diagnostic measures including US, CT and MRI are then discussed.

Electrophysiology↗
PubMed1990

Effect of gastric mucus on the uptake of the carcinogen MNNG by gastric mucosal DNA.

In prostaglandin E2 (PGE2)-, pirenzepine-, and indomethacin-administered rats, the incorporation of N-[methyl-3H]-N'-nitro-N-nitrosoguanidine ([methyl-3H]MNNG) into gastric mucosal DNA was measured quantitatively by liquid scintillation counting after intragastric instillation of [methyl-3H]MNNG. The amount of incorporation was 25.4 +/- 5.9 pmol/mg DNA in control rats, 11.7 +/- 3.8 pmol/mg DNA in PGE2-administered rats, 6.2 +/- 5.6 pmol/mg DNA in pirenzepine-administered rats, and 42.9 +/- 14.4 pmol/mg DNA in indomethacin-administered rats. PGE2 and pirenzepine significantly decreased the incorporation as compared with the control group. In contrast, indomethacin increased the incorporation. In addition, gastric mucosa of these drug-treated rats was studied histochemically. PGE2 and pirenzepine increased secretion of gastric mucus whereas indomethacin decreased it. It is possible that gastric mucus has a protective effect not only against ulcerogenic agents but also against carcinogens. It is considered that gastric mucus plays an important role in the defense mechanism against carcinogenesis.

Animals↗
PubMed1989

Ultrasonographic findings in gastric cancer: in vitro and in vivo studies.

Ultrasonography was performed in 45 cases of gastric cancer. Specimens from all 45 cases of gastric cancer were subjects to ultrasonographic study by the water immersion method for comparison with histology. In 32 of these 45 cases in vivo ultrasonographic evaluation was performed prospectively. The overall accuracy rates for the diagnosis of the depth of cancerous invasion were almost 80% in both in vitro and in vivo studies. In vivo ultrasonographic findings agreed well with those from the specimen studies. Ultrasonography was considered to be useful in the diagnosis of gastric malignancies.

Humans↗
PubMed1987

Immunoglobulin therapy in the West syndrome.

An examination was made of high dose non-treated immunoglobulin (NTIG) therapy at an early stage of the West syndrome (WS). Six patients with cryptogenic WS who suffered attacks ranging from 15 days to 6 months (mean 70 days) and 5 patients with symptomatic WS who suffered attacks ranging from 14 days to 4 months (mean 32 days), were administered NTIG 6-10 times intravenously at 100-200 mg/kg of body weight at intervals of 2 or 3 weeks. All patients with cryptogenic WS showed complete remission in accordance with normalized electroencephalogram (EEG) without following anticonvulsants medication. Of the 5 patients with symptomatic WS one patient showed cessation of clinical seizures in agreement with EEG improvement and 2 other patients revealed transient cessation of clinical seizures with recurrence. In cases of complete remission, the energy percentage of the power spectrum for each frequency band displayed a tendency toward gradual decrease of delta wave band in correspondence with the increase of theta wave band percentage after NTIG therapy, suggesting that high dose NTIG may be useful for early treatment of cryptogenic WS and for inhibiting brain deterioration owing to epileptic encephalopathy.

Anticonvulsants↗
PubMed1987

Usefulness of blood parameters, especially viscosity, for the diagnosis and elucidation of pathogenic mechanisms of the hand-arm vibration syndrome.

In the present study it was found that, in vibrating-tool operators with Raynaud's phenomenon, whole blood viscosity was significantly higher than in operators without Raynaud's phenomenon at shear rates from 230 to 11.5 s-1. In addition rats were experimentally exposed to local vibration (60 Hz, 5 g) on their hind limbs for 4 h/d for 30 or 90 d. In the case of 30-d exposure, the small arteries in the exposed site did not change. However, after exposure for 90 d, disruption of the internal elastic lamina was observed in the small arteries. The disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibers. The fibro-cellular thickening of the intima was further augmented, and, in addition, a complete stenosis of the small lumen of the small artery was observed. Medial thickness did not show significant differences between the control and exposed groups for either exposure duration. The whole blood viscosity was significantly increased by the 90-d but not by the 30-d exposure. These results suggest that there are some relationships between the increase in whole blood viscosity and the intimal thickening of some small arteries in the exposed site.

Animals↗
PubMed1986

[Changes in the forearm tcPO2 following the cold water immersion test].

The purpose of this study is to apply changes in forearm transcutaneous PO2 (tcPO2) during the cold water immersion test (5 degrees C, for 10 min) to the diagnosis of vibration syndrome. Forearm tcPO2 in healthy controls increased gradually up to 3 min after the start of the cold water immersion and decreased thereafter. It returned to almost the same level before immersion 5 min after the start. In the workers using vibrating tools manifesting Raynaud's phenomenon, forearm tcPO2 also increased up to 3 min after the start as in healthy controls, but no change was observed thereafter. The difference between the level of forearm tcPO2 at 3 min and that at 10 min after the start of the immersion (Forearm tcPO2 recovery index, newly devised by authors) in workers using vibrating tools was significantly lower than that in healthy controls. Therefore, investigation of changes in forearm tcPO2 following the cold water immersion test is considered to be a useful objective item which can contribute to the diagnosis of vibration syndrome.

Aged↗
PubMed1985

Study on the mechanism of the appearance of noise effects.

This study was undertaken to investigate the dose-response relationship between the biological effect and noise exposure, and to consider the mechanism of the appearance of noise effects. Rats were exposed to noise at intensities of 60 dB (A), 80 dB (A) and 100 dB (A) for 240 min and examined for the change of activities of dopamine-beta-hydroxylase (DBH) in serum and adrenal glands. Plasma cyclic adenosine 3',5'-monophosphate (c-AMP) levels were also measured. Some rats were given 6-hydroxydopamine (6-OHDA) as a chemical sympathectomyzing agent 20 h before noise exposure in order to consider the mechanism of the appearance of noise effects. By noise exposure, serum DBH activity was significantly (P less than 0.01) increased at each intensity compared with the control group, but there were no remarkable changes in adrenal DBH activity. Plasma c-AMP level was also significantly elevated in response to the noise stress. When the rats, which had been pretreated with 6-OHDA, were exposed to noise with an intensity of 100 dB (A), the response of serum DBH activity was no longer observed. Therefore it is suggested that the effect due to noise exposure appears through the post-ganglionic sympathetic nerve fiber.

Adrenal Glands↗
PubMed1985

Influence of local vibration on plasma creatine phosphokinase (CPK) activity.

This study was designed to obtain basic information about the mechanism of the occurrence of muscular disorders after exposure to vibration. The hind legs of rats were exposed to acute and chronic local vibration at frequencies of 30, 60, 120, 240, 480, and 960 Hz with a constant acceleration of 50 m/sec2. The exposure time was four hours for acute, and four hours a day for two weeks continuously for chronic exposure. Blood was collected after exposure to measure plasma creatine phosphokinase (CPK) activity. In both exposure groups the activity of plasma CPK was significantly higher at 30, 60, 120, 240, and 480 Hz compared with the control group and was especially high at 30 Hz; there was no significant change at 960 Hz. As a result of an analysis of the CPK isoenzymes, the increase in plasma CPK activity was shown to be due to the activity of the plasma CPK-MM fraction, originating in the skeletal muscle. Plasma CPK activity showed a tendency to decrease gradually with the increase in vibration frequency during acute exposure but showed no such tendency during chronic exposure. There was no remarkable pathohistological change in muscle preparations from the hind legs, hence it was presumed that the increase in plasma CPK activity was caused not by the morphological changes of muscle but by other mechanisms, such as an increase in the permeability of the cell membrane.

Animals↗
PubMed1985

Effects of whole body vibration on biogenic amines in rat brain.

The effects of whole body vibration on the concentrations of noradrenaline (NA), dopamine (DA), and serotonin (5-HT) in the whole brain and brain regions of rats were investigated. Compared with control rats, vibration with 20 Hz frequency decreased the brain concentration of NA only when the acceleration (intensity) was increased to 5.0 G (p less than 0.05). The concentration of DA in the whole brain was not affected by acceleration. When acceleration was kept at a constant 0.4 G level and rats were exposed for the same 240 minute period to 5, 20, or 30 Hz vibration, neither NA nor DA concentrations changed in the whole brain. Regional changes in the concentration of biogenic amines in the brain of rats exposed to vibration of 20 Hz and 5.0 G showed few significant differences. Thus NA significantly decreased only in the hypothalamus (p less than 0.01), although in the hippocampus the decrease was nearly significant (p less than 0.10). The concentration of 5-HT significantly increased in the hypothalamus and cerebellum (p less than 0.05). DA tended to increase in the cortex and decrease in the striatum (p less than 0.10). These experiments seem to indicate that NA in the whole brain and especially in the hypothalamus is a better indicator of vibration exposure than 5-HT, and that NA is affected by the intensity but not by the frequency of vibration. NA and 5-HT in the hypothalamus change in the opposite direction. DA concentrations in the brain are basically unaffected by vibration.

Acceleration↗
PubMed1984

Preliminary evaluation of dose-effect relationships for vibration induced white finger in Japan.

Habitual use of many vibrating tools has been found to be connected with the appearance of various disorders affecting the blood vessels, nerves, bones, joints, muscles or connective tissues of the hand and forearm. The vibration exposures required to cause these diseases are not known exactly, either with respect to vibration intensity and the vibration frequency spectrum, or with respect to daily exposure time and total exposure period. The purpose of this study is to investigate available data on the physical conditions in Japan that have caused vibration induced white finger (VWF) and attempt to establish approximate relationships between vibration conditions and prevalence of VWF. The vibration conditions were evaluated using the method of vibration assessment recommended by the International Standardized Organization, which uses the weighted vibration level of the frequency weighted, dominant, single axis component of vibration directed into the hand. A clear correlation between level, prevalence of VWF and exposure period can be found. The results also suggest the relationship between the weighted levels and latent intervals. These dose-effect relationships enable the prediction of the average latent interval for a population group and the range of progression of the disorders--all from a measurement of the vibration entering the hands. In Japanese cases, 4, 8, and 15% of VWF prevalence correspond with 10, 20, and 40% of VWF prevalence in the Draft International Standard ISO/DIS 5349 (1982) within the weighted vibration level range of 2 to 50m X s-2.

Adult↗