Biomedical subjects

N Takeda

Publications and source records attributed to N Takeda.

644 records · Page 36Linked to original sources

PubMedDate not supplied

Dolichoectatic basilar artery: a review of 23 cases.

The dolichoectatic basilar artery was found in 23 cases during a 10-year period. The 19 males and 4 females ranged in age from 30 to 69 years (mean: 55 years). Hypertension was noted in 17 patients. In seventeen (74%) of the present cases this anomaly could be visualized with CT scan. Seven patients (30%) presented with pontine infarction, which was identified on CT scan in all cases. Vertebro-basilar insufficiency was found in four patients. One patient had transient ischemic attacks. There were facial spasms in four patients and impairment of the lower cranial nerves in one. One patient exhibited cerebellar hemorrhage. In two patients this anomaly was found incidentally. Associated intracranial aneurysms were identified in seven patients, including fusiform aneurysms in 4 and saccular aneurysms in 3. Three patients had an accompanying hydrocephalus. The dolichoectatic basilar artery is associated with various consequences especially in relation to the pathogenesis of brainstem infarction. When this anomaly is diagnosed by CT findings, even if it is clinically asymptomatic, it may be better to treat these patients with medical therapy used to prevent ischemic stroke.

Adult↗

PubMedDate not supplied

Histaminergic mechanism of motion sickness. Neurochemical and neuropharmacological studies in rats.

Rats were rotated about two parallel axes to produce motion sickness, and the histamine levels in their hypothalamus and pons-medulla oblongata were measured. Rotation for 60 min induced kaolin intake, which is a behavioral index of motion sickness in rats, and increased the histamine levels in the hypothalamus and pons-medulla oblongata, the highest levels occurring after 15 min of rotation. In bilaterally labyrinthectomized rats, no rise in histamine level was observed. alpha-Fluoromethylhistidine (alpha-FMH), which depletes the neural component of histamine in the brain, suppressed kaolin intake induced by rotation. These findings demonstrated that the histaminergic neuron system contributes to development of motion sickness, and suggested that alpha-FMH may be effective as an anti-motion sickness drug.

Animals↗

PubMedDate not supplied

Effect of vestibulo-cerebellar lesions on asymmetry of vertical optokinetic functions in the squirrel monkey.

The role of the cerebellar uvula and nodulus in vertical optokinetic after-nystagmus (OKAN) was studied in 4 squirrel monkeys. Aspiration ablation of the uvula and nodulus resulted in no significant change in the initial or peak gain of vertical optokinetic nystagmus (OKN) during the 24-week post-operative observation. However, the asymmetry of vertical OKAN was significantly altered. Using a protracted upward OK stimulus, slow phase-down OKAN-II, which was not seen pre-operatively, was significantly increased. In contrast, a downward OK stimulus produced little change in slow phase-up OKAN-II. Thus, the asymmetric degree of vertical OKAN-II was decreased after uvulonodulectomy. In addition, there was a post-operative reduction in the vertical oculomotor stability. When slow-phase eye velocity of OKAN was plotted along the time scale, the amplitude and frequency of the sinusoidal pattern was increased. OKAN-III and OKAN-IV were found in 50% of the monkeys after uvulonodulectomy. It is therefore thought that inhibition and directional control from the uvula and nodulus influence the stability and asymmetrical behaviour of the leaky integrator in the second order output system.

Animals↗

PubMedDate not supplied

Recovery of the otolith-ocular reflex after unilateral deafferentation of the otolith organs in squirrel monkeys.

The enhancement of the vestibulo-ocular reflex (VOR) gain in the eccentric rotation is mediated by the otolith organs. Functional recovery of the otolith-ocular reflex after deafferentation of the otolith organs was examined in squirrel monkeys, using the enhancement of the eccentric VOR gain as an indicator of the reflex. After unilateral deafferentation of the otolith organs, the enhancement of the eccentric VOR gain decreased and then recovered completely within eight weeks. However, the eccentric VOR gain was not enhanced after contralateral side lesions. These findings demonstrate that functional recovery of the otolith-ocular reflex is achieved after unilateral deafferentation of the otolith organs, and that afferents from the remaining otolith organs are necessary for the functional compensation.

Animals↗

PubMedDate not supplied

Effects of anti-cholinergic and cholinergic drugs on habituation to motion in rats.

The effects of the anti-cholinergic drug scopolamine, an anti-motion sickness drug, and of the cholinergics physostigmine and neostigmine on habituation to motion sickness in rats were examined using pica, measured as eating of kaolin, as a behavioural index of motion sickness in rats. Rats were rotated around two axes for 1 h once a day for 10 or 11 days. Rotation-induced kaolin intake of control rats gradually decreased from day 9 of daily rotation. Test rats were not treated for the first 3 days, given drugs on days 4-7 of rotation and then again given no drugs for the next 3 or 4 days. Rotation-induced kaolin intake of test rats was compared to that of controls. Results showed that TTS (Transdermal Therapeutic System)-scopolamine administration facilitated habituation to rotation, whereas physostigmine, a centrally acting cholinesterase inhibitor, suppressed it, and neostigmine, a peripherally active cholinesterase inhibitor, had no effect on habituation at all. These findings suggest that the central cholinergic neuron system plays an important role in the neural mechanism of habituation to motion in rats.

Animals↗

PubMedDate not supplied

A simple novel method of biliary drainage: gallbladder serosal wrapping after open choledochotomy.

In this study, we developed a new, simple technique for biliary drainage after open choledochotomy of choledocholithiasis. After the absence of intraductal stones was established by operative cholangiography and cholangioscopy, preserved gallbladder serosal wrapping was performed by inclosing a polyethylene tube (C-tube), which was inserted from the cystic duct to optimal portion of choledochus, within the gallbladder bed, with continuous suture of the preserved serosa of the gallbladder using 4-0 absorbable thread. This method was used in the cases of 8 patients. There was neither bile leakage nor residual bile duct stones. The C-tube could be removed after 7 days following surgery. The average hospital stay was 12.3 +/- 6.6 days. We propose that this procedure would be very simple and useful, and it would significantly shorten hospital stays after open choledochotomy of choledocholithiasis.

Drainage↗

PubMedDate not supplied

High prevalence of hepatitis B virus infection amongst Tibetans in Nepal.

Tibetans have been living in Nepal since 1959. Study of the prevalence of viral hepatitis among them showed that they have a high prevalence of hepatitis B virus (HBV) infection. Prevalence of total HBV infection and Hepatitis B surface antigen (HBsAg) among them was 61% and 16% compared to 10.0% and 0.7% respectively among the Nepalese. The predominant HBsAg subtype among the Tibetans was 'ayw'. Perinatal and childhood transmission was found important in the spread of HBV infection among the Tibetans.

Carrier State↗

PubMedDate not supplied

Influence of long-term arotinolol treatment on myocardial mechanics and ventricular myosin isoenzymes in spontaneously hypertensive rats.

Alterations in myocardial mechanics and left ventricular myosin isoenzymes by long-term treatment of hypertension with arotinolol were examined in spontaneously hypertensive rats. Approximately 20 mg/kg/day arotinolol was administered to 22-week-old male spontaneously hypertensive rats for 8-10 weeks. There was no significant difference in systolic blood pressure between arotinolol-treated and untreated rats. However, ventricular weight tended to decrease in the arotinolol-treated group, although not significantly. There were no significant differences in isometric developed tension and dT/dtmax of isolated left ventricular papillary muscles between the arotinolol-treated and untreated groups. The left ventricular myosin isoenzyme pattern, on the other hand, obtained by pyrophosphate gel electrophoresis, showed a significant shift toward VM-1 as a result of long-term arotinolol treatment.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

Effects of bunazosin on plasma glucose levels in hypertensive diabetic patients.

Twenty-nine hypertensive diabetic patients received 1.5 to 4.0 mg of bunazosin daily for three months. Both systolic and diastolic blood pressures were significantly reduced by the bunazosin treatment, while heart rate was unchanged. No significant changes were noted in fasting plasma glucose levels or in levels of hemoglobin A1c. Serum lipid levels remained unchanged during treatment. It is concluded that bunazosin does not adversely affect glucose metabolism or increase serum lipid levels in hypertensive diabetic patients.

Adrenergic alpha-Antagonists↗

PubMedDate not supplied

Localization and fine structure of calcitonin gene-related peptide (CGRP)-like immunoreactive nerve fibres in the organ of Corti of guinea pigs by immunohistochemistry.

The localization and fine structure of calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRPI) fibres in the guinea pig cochlea were examined using immunohistochemistry. Numerous CGRPI fibres were located in the inner spiral bundle corresponding to the lateral system of the olivocochlear bundle. Immunoelectron microscopic analysis demonstrated that the CGRPI fibres belonged to the efferent terminals and some of them made synaptic contacts with peripheral neurites of the auditory nerve. These findings suggested that the olivocochlear CGRP neuron system influenced the neural activity of the auditory nerve, which conveys auditory information from the cochlea to the central nervous system.

Animals↗

PubMedDate not supplied

Beta-adrenoceptor mediated signal transduction in congestive heart failure in cardiomyopathic (UM-X7.1) hamsters.

In view of the lack of information regarding the status of beta-adrenoceptor mediated signal transduction mechanisms at severe stages of congestive heart failure, the status of beta-adrenoceptors, G-proteins and adenylyl cyclase activities was examined in 220-275 day old cardiomyopathic hamster hearts. Although no changes in the Kd values for beta 1- and beta 2-adrenoceptors were seen, the number of beta 1-adrenoceptors, unlike that of beta 2-adrenoceptors, was markedly decreased in cardiac membranes from failing hearts. The activation of adenylyl cyclase in the failing hearts by different concentrations of isoproterenol was also attenuated in comparison to the control preparations. The basal adenylyl cyclase activity in cardiac membranes from the failing hearts was not altered; however, the stimulated enzyme activities, when measured in the presence of forskolin, NaF or Gpp(NH)p were depressed significantly. The functional activity of Gs-proteins (measured by cholera toxin stimulation of adenylyl cyclase) was depressed whereas that of Gi-proteins (measured by pertussis toxin stimulation of adenylyl cyclase) was increased in the failing hearts. Not only were the Gs- and Gi-protein contents (measured by immunoblotting) increased, the bioactivities of these proteins as determined by ADP-ribosylations in the presence of cholera toxin and pertussis toxin, respectively, were also higher in failing hearts in comparison to the control values. Northern blot analysis revealed that the signals for Gs- and Gi-protein mRNAs were augmented at this stage of heart failure. These results indicate that the loss of adrenergic support at severe stages of congestive heart failure in cardiomyopathic hamsters may involve a reduction in the number of beta 1-adrenoceptors, and an increase in Gi-protein contents as well as bioactivities in addition to an uncoupling of Gs-proteins from the catalytic site of adenylyl cyclase in cardiac membrane.

Adenylate Cyclase Toxin↗

PubMedDate not supplied

Effects of caloric vestibular stimulation on parietal and temporal blood flow in human brain: a consecutive technetium-99m-HMPAO spect study.

The effects of caloric vestibular stimulation on regional cerebral blood flow (rCBF) of the parietal and temporal cortex were examined in 10 healthy volunteers. The consecutive 99mTe-hexamethyl-propyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) method with region of interest analysis was used. Changes in rCBF induced by caloric stimulation with cold air (25 degrees C) were evaluated in comparison with those induced by control stimulation with air at body temperature (37 degrees C). Caloric stimulation with cold air induced vertigo in 4 subjects, dizziness in 2, and no sensation of self-motion in the remaining 4 subjects, whereas, control stimulation did not induce the sensation of self-motion in any subject. Although both parietal and temporal rCBF were slightly decreased during caloric stimulation, a correlation could be established between the magnitude of left-right differences in change of parietal rCBF and the degree of self-motion perception induced by cold-air caloric stimulation, as compared to control stimulation. Left-right differences in change of parietal rCBF in subjects with vertigo during caloric stimulation were significantly higher than those in subjects without any sensation of self-motion. In contrast, there was no correlation between the magnitude of left-right difference in change of parietal rCBF and maximum slow phase eye velocity induced by caloric stimulation. These findings suggest that the parietal lobe is involved in the perception of vertigo due to vestibular stimulation, but not in the vestibulo-ocular reflex.

Adult↗

PubMedDate not supplied

A ground-based animal model of space adaptation syndrome.

We examined the effect and aftereffect of acute or chronic load of hypergravity produced by an animal centrifuge, on pica (that is, kaolin intake) in the rat as an index of motion sickness. Although the degree of pica initially induced by acute or chronic hypergravity was not different, the rate of decline of increased kaolin intake over poststimulus days was different. Pica after a 1-h load of 2g decreased rapidly. On the other hand, pica lasted 3 days after a 48-h load of 2g. These findings suggest that the aftereffects of chronic hypergravity application on pica are due to motion sickness induced by readaptation to normal gravity, and they support our idea that after adaptation to a hypergravity environment, return and readaptation to the normal gravity can simulate exposure and adaptation to microgravity. We concluded that motion sickness in rats induced by the aftereffects of chronic hypergravity stimulation can be used as a ground-based animal model of space adaptation syndrome.

Animals↗

PubMedDate not supplied

Asymptomatic hemobilia with idiopathic thrombocytopenic purpura.

A severe but asymptomatic anemia developed in a patient with idiopathic thrombocytopenic purpura. Urgent upper gastrointestinal endoscopy disclosed massive bleeding from the papilla of Vater and we inferred that the anemia was caused by hemobilia. The bleeding point could not be detected, but the bleeding was stopped with conservative therapy. Although several cases of hemobilia have been reported in patients with bleeding tendency, this is the first case to be reported in a patient with idiopathic thrombocytopenic purpura.

Adult↗