Search PubMed⌕ Search

Biomedical subjects

H Fukuda

Publications and source records attributed to H Fukuda.

At least 883 records · Page 49Linked to original sources
PubMed1988

Positron CT imaging of an impending stroke.

We present PET findings of a case of a transient ischemic attack which later progressed to cerebral infarction. Cerebral blood flow at the stroke focus in the right parietal cortex measured after a TIA attack and before stroke was as low as 24 ml/100 g/min with some increase in oxygen extraction fraction and blood volume. The condition was compatible with "misery perfusion". This case may be an example suggestive that the "misery perfusion sign" is a warning of impending stroke and its poor prognosis if left without appropriate treatments.

Aged↗
PubMed1988

Thermoregulatory adjustments during continuous heat exposure.

Body temperature regulation was studied in 6 male subjects during an acclimation procedure involving uninterrupted heat exposure for 5 successive days and nights in a hot dry environment (ambient temperature = 35 degrees C, dew-point temperature = 7 degrees C; air velocity = 0.2 m.s-1). Data were obtained at rest and during exercise (relative mechanical workload = 35% VO2max). At rest, hourly measurements were made of oesophageal and 4 local skin temperatures, to allow the calculation of mean skin temperature, and of body motility and heart rate. During the working periods these measurements were made at 5 min intervals. Hourly whole-body weight loss was measured at rest on a sensitive platform scale while in the working condition just before starting and immediately after completing the bicycle exercise. The results show that, in both exercise and at rest, the successive heat exposures increased the sweat gland output during the first 3 days. Afterwards, sweat rate decreased without any corresponding change in body temperature. For the fixed workload, the sweat rate decline was associated with a decrease in circulatory strain. Adjustments in both sweating and circulatory mechanisms occur in the first 3 days of continuous heat exposure. The overall sweat rate decline could involve a redistribution of the regional sweating rates which enhances the sweat gland activities of skin areas with maximal evaporative efficiencies.

Acclimatization↗
PubMed1988

Long-term depletion of histamine in guinea-pigs by administration of alpha-fluoromethylhistidine, a specific inhibitor of histidine decarboxylase; effect on the sensitivity of histamine receptors.

The effect of intraperitoneal administration of alpha-fluoromethylhistidine (alpha-FMH), a specific inhibitor of histidine decarboxylase, at a dose of 100 mg/kg twice a day for 6 weeks on the sensitivity of histamine receptors in the guinea-pigs was examined. The histamine contents in the ileum, heart and brain after the treatment decreased to about 54%, 83% and 9-62% (depending on the region), respectively, of those of controls. However, there were no significant difference in the histamine-induced contraction of the ileum and atrium, the maximal binding (Bmax) and the dissociation constant (Kd) of [3H]-mepyramine binding to membrane fractions of the ileum and brain (except the cortex) and the increase of cyclic AMP formation induced by histamine in membranes of the heart and brain (except the cortex) between alpha-FMH-treated- and untreated animals. These results suggest that long-term histamine depletion dose not significantly affect the sensitivity of histamine receptors of guinea-pig except in the brain cortex.

Adenylyl Cyclases↗
PubMed1988

Role of the forebrain commissure and hemispheric independence in photosensitive response of epileptic baboon, Papio papio.

The effect of monocular intermittent light stimulation (ILS) of either hemivisual field (HVF) of the full visual field (FVF) was examined in Papio papio with or without forebrain bisection. ILS of the HVF or the FVF in non-bisected baboons produced bisymmetrical and bisynchronous spike and wave which was followed by a self-sustained seizure without EEG evidence of hemispheric independence. ILS of the FVF in bisected baboons also produced bilateral spike and wave and self-sustained seizures of a similar nature. With ILS of the HVF in bisected baboons, EEG seizures lateralized largely to the contralateral hemisphere and when the ILS of the HVF was switched to the other eye similarly lateralized spike and wave and a self-sustained seizure were produced in the other hemisphere. These findings suggest that (a) the forebrain commissure, most probably the corpus callosum (and possibly the hippocampal commissure), plays a major but not unique role in the bisynchronization and generalization of the ILS-induced spike and wave and the self-sustained seizures, and (b) each hemisphere possesses independent cerebral excitability to the ILS.

Animals↗
PubMed1988

Active site histidine in pig liver aminolevulic acid dehydratase modified by diethylpyrocarbonate and protected by Zn2+ ions.

1. The effect of diethylpyrocarbonate (DEP) (0.1-0.35 mM) on the purified pig liver amino-levulic acid dehydratase (ALA-D) containing 0.3 g-atoms Zn/subunit, under different pHs (6.0-7.5), temperature (0-18 degrees C) and time (0-60 min) was studied. 2. Three histidyl residues/subunit were modified by DEP (0.2 mM, pH 6.8), but activity was completely lost after the first one had reacted, indicating the presence of one histidine residue essential for ALA-D catalysis. Reactivation by treatment with hydroxylamine (0.7 mM, pH 7.0) confirmed that only histidine and no other nucleophile amino acids were directly involved in DEP inhibition. 3. Zn ions (0.5 mM) and the substrate ALA (5-10 mM) protected against DEP inactivation, protection was dependent on pH. 4. Sn, Se, Hg, Cd, Mn, Co and Pb (0.01-0.1 mM) did not significantly protect ALA-D against inactivation. 5. It is concluded that the substrate and Zn binding sites and the essential histidyl residues are in close proximity in the active center. It is proposed that in the catalytic synthesis of porphobilinogen from ALA, histidine groups have the specific role of transporting protons from the aqueous media to a hydrophobic active site.

Animals↗
PubMed1988

Effects of L-threo-dihydroxyphenylserine on spinal reflexes and decerebrate rigidity in rats.

1. The effects of a noradrenaline precursor, L-threo-3,4-dihydroxyphenylserine (L-DOPS), on spinal mono-(MSR) and polysynaptic reflexes (PSR) and decerebrate rigidity, were studied. 2. Although a low dose of L-DOPS (10 mg/kg, i.v.) did not affect MSR or PSR in C1 spinal rats, high doses of L-DOPS (50 and 100 mg/kg, i.v.) moderately enhanced the amplitudes of both MSR and PSR. 3. Clorgyline-HCl (1 mg/kg, i.v.), an MAO inhibitor, enhanced the excitatory effects of low-dose L-DOPS (10 mg/kg, i.v.) on both reflexes. 4. Benserazide-HCl (1 mg/kg, i.v.), an L-aromatic amino acid decarboxylase inhibitor, decreased the pressor effect, but not the stimulatory effects, of L-DOPS (100 mg/kg, i.v.) on MSR and PSR. 5. L-DOPS (300 mg/kg, i.p. or i.d.) did not affect the muscle tone of rigid hindlimbs caused by radio frequency lesioning of the midbrain. 6. These results suggest that the moderate enhancing effects of L-DOPS on MSR and PSR are due to conversion of L-DOPS to noradrenaline in the spinal cord.

Animals↗
PubMed1988

Different effects of norepinephrine and serotonin on the electrical toe stimulation-induced reflexes in the rat spinal cord.

1. Electrical toe stimulation was shown to elicit reflex potentials in the ipsilateral common peroneal nerve in the rat. 2. This reflex consisted of the spinal reflex and the spino-bulbo-spinal reflex (SBS reflex). 3. Administration of norepinephrine into the subarachnoid space enhanced the spinal reflex but depressed the SBS reflex. On the other hand, serotonin enhanced both reflexes. 4. These different effects of norepinephrine and serotonin suggest different control of nociceptive reactions by these biogenic amines.

Animals↗
PubMed1988

Accumulation of 2-deoxy-2-[18F]fluoro-D-galactose in the liver by phosphate and uridylate trapping.

To investigate the highest accumulation of 2-deoxy-2-[18F]fluoro-D-galactose ([18F]FdGal) in the liver, metabolic studies with [18F]FdGal were carried out in Wistar rats for 120 min after i.v. injection. As main metabolites 2-deoxy-2-[18F]fluoro-D-galactose 1-phosphate ([18F]FdGal-1-P) and UDP-2-deoxy-2-[18F]-fluoro-D-galactose (UDP-[18F]FdGal) were identified in the liver and other tissues. The [18F]FdGal was phosphorylated by galactokinase. The phosphorylation rate was very rapid in the liver, in which at 5 min after injection 81% of 18F was detected as [18F]FdGal-1-P. After this time the phosphate form decreased with time, which was explained by conversion of [18F]FdGal-1-P to UDP-[18F]FdGal by UDP-glucose: galactose-1-phosphate uridyltransferase. At 120 min after injection 77% of the 18F was measured in the UDP-[18F]FdGal. In the brain both reaction rates were slower than in the liver. Both phosphate and uridylate derivates were also observed as main metabolites in the heart, lung, spleen and small intestine. On the other hand, a small amount of [18F]FdGal-1-P was detected in the plasma, in which the percentage of phosphate increased gradually and was 6% at 120 min. These results show that the [18F]FdGal metabolism in tissue results in phosphate and uridylate trapping and that the [18F]FdGal has potential for measuring in vivo galactose metabolism with positron emission tomography.

Animals↗
PubMed1988

Compression therapy for parotid haemangioma in infants. A report of three cases.

Three cases of parotid haemangioma in infants are presented. Compression therapy was applied in these cases using a resin splint and a headcap and they were very effective. In the first case, the lesion had begun to reduce in volume within two weeks after starting the compression therapy. The haemangioma had disappeared completely in sixteen months. In the second and third cases, the lesions have disappeared in eight months and fifteen months, respectively. In all of the cases, no side effects were noticed. We believe that compression therapy is a safe and effective treatment modality for haemangiomas in infants even though these may disappear spontaneously in some cases.

Bandages↗
PubMed1988

Effect of continuous heat exposure on sleep stages in humans.

Six young men were exposed to a thermoneutral environment of air temperature (Ta) 20 degrees C for 5 days and nights followed by an acclimation period of 5 days and nights at Ta 35 degrees C and 2 recovery days and nights at Ta 20 degrees C. Electrophysiological measures of sleep, esophageal temperature, and mean skin temperature were continuously monitored. The total nocturnal body weight loss was measured by a sensitive platform scale. Compared with the 5 nights of the baseline period at 20 degrees C, sleep patterns showed disturbances at 35 degrees C. Total sleep time was significantly reduced, while the amount of wakefulness increased. The subjects exhibited fragmented sleep patterns. The mean duration of REM episodes was shorter at 35 degrees C than at 20 degrees C of Ta, while the REM cycle length shortened. In the acclimation period, there was no change in sleep pattern from night to night, despite adaptative adjustments of the thermoregulatory response. The protective mechanisms of deep body temperature occurring with heat adaptation did not interact with sleep processes. Upon return to baseline condition, a recovery effect was observed on a number of sleep parameters which were not significantly affected by the preceding exposure to prolonged heat. This would suggest that during exposure to dry heat, the demand for sleep could overcome that of other regulatory functions that are temperature-dependent. Therefore, a complete analysis of the effect of heat on sleep parameters can be assessed only if heat exposure is compared with both baseline and recovery periods.

Adult↗
PubMed1988

A pitch-synchronous analysis of hoarseness in running speech.

A method of pitch-synchronous acoustic analysis of hoarseness requiring a voice sample of only four fundamental periods is presented. This method calculates a noise-to-signal (N/S) ratio, which indicates the depth of valleys between harmonic peaks in the power spectrum. The spectrum is calculated pitch synchronously from a Fourier transform of the signal, windowed through a continuously variable Hanning window spanning exactly four fundamental periods. A two-stage procedure is used to determine the exact duration of the four fundamental periods. An initial estimate is obtained using autocorrelation in the time domain. A more precise estimate is obtained in the frequency domain by minimizing the errors between the preliminary calculated power spectrum and the predicted spectrum spread of a windowed harmonic signal. Analysis of synthesized voices showed that the N/S ratio is sensitive to additive noise, jitter, and shimmer, and is insensitive to slow (8 Hz) modulation in fundamental frequency and amplitude. An analysis of pre- and postoperative voices of six patients with benign laryngeal disease showed that the N/S ratio for vowel /u/ in running speech consistently improved after surgery for all subjects, in agreement with their successful therapeutic results.

Hoarseness↗
PubMed1988

Preparation of a Cell-Free, Isobutene-Forming System from Rhodotorula minuta.

The cell-free isobutene-forming system of Rhodotorula minuta IFO 1102 was prepared. This system consisted of isovaleric acid, NADPH, and a cell extract. The maximal activity obtained by using the described cell-free system was 17 nl/mg of protein per h. It appears that this cell-free isobutene-forming system operates in living cells of R. minuta.

Journal Article↗
PubMed1988

Biochemical aspects of Parkinson-dementia complex.

Positron emission tomography of a parkinsonian patient with dementia revealed a decreased cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in the cerebral cortex and deep gray matter, whereas a parkinsonian patient without dementia showed a decrease in CBF and CMRO2 in the deep gray matter, but not in the cerebral cortex. The ratio of 3,4-dihydroxyphenylacetic acid/L-dopa in the plasma after L-dopa administration was significantly increased in parkinsonian patients with hallucinations, indicating an accelerated metabolism of L-dopa. The concentration of 5-hydroxyindoleacetic acid (5HIAA) was decreased in the cerebrospinal fluid of parkinsonian patients with psychiatric symptoms, especially with visual hallucinations. The serotonin level in mouse striatum was significantly reduced 1 week after methylphenyltetrahydropyridine (MPTP) injection, though returned to normal in 4 weeks. The 5HIAA level increased at both 1 and 4 weeks. The activity of tryptophan hydroxylase was increased in the striatum 1-4 weeks after MPTP injection, but was unchanged in the cerebral cortex. The choline acetyltransferase (ChAT) activity was significantly decreased in the hippocampus 1 week, but not 4 weeks after MPTP. The ChAT activity was not changed in the frontal cortex at either 1 or 4 weeks.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

A case of postpartum hypopituitarism (Sheehan's syndrome) associated with severe hyponatremia and congestive heart failure.

A case of a 69-year-old woman with postpartum hypopituitarism (Sheehan's syndrome) associated with congestive heart failure and severe hyponatremia is reported. She developed congestive heart failure after cholecystectomy, and marked improvement was noted by treatment with oxygen, digoxin, furosemide, and dopamine. Two weeks after surgery, she became confused, and hyponatremia, 106 mEq/l, was detected. She was referred to us. Past history revealed postpartum hemorrhage at the age of 34, followed by a failure to lactate, menoschesis, and loss of pubic hair and axillary hair. Hypertonic saline (1.5%) infusion and water restriction increased her serum sodium concentration into the low normal range. Despite hyponatremia, serum vasopressin was not suppressed. Basal levels of pituitary hormones were low, and they did not respond to provocation tests. Marked impairment of water excretion was noted, and plasma vasopressin was not suppressed during a water-loading test. These results suggest that inappropriately increased vasopressin played an important role in impaired water excretion, and this defect could have been responsible for the development of hyponatremia and congestive heart failure in this patient.

Aged↗