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Biomedical subjects

C Ito

Publications and source records attributed to C Ito.

At least 145 records · Page 8Linked to original sources
PubMed1991

Congestive heart failure model in rabbits: effects of digoxin and a drug containing toad venom.

A low-output-type heart failure model was established in rabbits by protease treatment of the surface of the left ventricular anterior wall. Heart rate, aortic blood flow (AoF), left ventricular pressure (LVP) and maximal rate of rise of LVP (max dP/dt) in this model were maintained at lower levels than in normal rabbits, while left ventricular end-diastolic pressure (LVEDP) and systemic vascular resistance (SVR) were maintained at higher levels, and mean blood pressure (MBP) remained at a normal level. Intraduodenal administration of digoxin and a drug containing toad venom (Kyushin:KY) improved the hemodynamic parameters by increasing the AoF, LVP and max dP/dt and by decreasing the LVEDP and SVR without a significant change in MBP. These results suggest that the beneficial effects of digoxin and KY on this heart failure model originate from their cardiotonic activity.

Amphibian Venoms↗
PubMed1991

Study of regional cerebral blood flow in experimental head injury: changes following cerebral contusion and during spreading depression.

Changes in regional cerebral blood flow (rCBF) following fluid-percussion brain injury (cerebral contusion) were studied in rats using the autoradiographic method. The direct current potential was monitored to identify spreading depression (SD). The rCBF was measured during SD and 2, 4, and 24 hours after injury. rCBF was almost nil in the contused area and decreased considerably in the cortices of the injured side for 4 hours after insult, then recovered by 24 hours. Focal relative rCBF increase occurred in the parietal cortex during SD, and was probably hyperperfusion due to SD. However, the rCBF did not increase over the sham-operated control. The injury probably caused hypoperfusion within 4 hours of insult and abolished the vascular response to SD.

Animals↗
PubMed1991

[Problems of Mason-Likar lead system in treadmill exercise electrocardiography].

A Mason-Likar (M-L) leads system has been widely used in the exercise electrocardiography (ECG) using treadmill for the detection of myocardial ischemia. In routine treadmill exercise ECG using M-L lead, we often observe different patterns of ST-T forms those of II, III and aVF on bipolar leads. In this study, on 213 patients, conventional 12 lead ECG and the M-L lead placement ECG were recorded both at supine and standing positions. A careful analysis was made on all the records of patterns, durations, and amplitudes of QRS and T waves. We also evaluated the ST trendgram of patients with no ischemic changes proven exercise TI-201 myocardial single photon emission tomography (SPECT). Quantitative examination showed no significant differences between those in precordial leads of the standard and the M-L lead system in any subjects. The augmented amplitude of QRS and T waves, the disappearance of abnormal Q-waves in II, III, aVF lead, the negative inversion in QRS phase in lead aVL an left axis deviation were often recognized with M-L lead placement. In treadmill exercise ECG, ST depression more than 1 mm in II, III, aVF lead was noted 14 out of 17 patients with no ischemic changes. The all ST-T changes showed "not-decrescendo" type in ST trendgram. We concluded that rigorous evaluation for electrical axis, the configuration of ST-T waves and the existence of myocardial ischemia in leads II, III, aVF was necessary on treadmill exercise ECG using M-L lead replacement.

Coronary Disease↗
PubMed1991

[Effects of the cortical subarachnoid hemorrhage on cerebral glucose metabolism].

Neurological deficits following human subarachnoid hemorrhage (SAH) have been related to the cerebral arterial spasm and the increase in intracranial pressure (ICP) secondary to the development of hydrocephalus. Metabolic depression in experiment study was thought as resulting from brain stem dysfunction. On the other hand, some reports have shown no relationship between vasospasm and neurological abnormalities. The mechanism of cerebral metabolism depression after SAH remains unclear. The effect of blood in the cortical subarachnoid space on the cerebral metabolism has not been known well. To investigate this effect, a new cortical SAH model was developed using rat and local cerebral glucose utilization (LCGU) after production of SAH was measured. A cortical SAH model: a small burr hole was made on the left parietal bone and the arachnoid membrane was pierced with a tapered glass-needle 60 mu tip in diameter. Fresh autologous non-heparinized arterial blood 0.04 ml was injected into subarachnoid space within 60 seconds through that needle. The blood extended over the left cerebral cortical surface with thin subarachnoid hematoma on the parietal cortex, but did not extend on the right hemisphere and the basal cistern. The increase in ICP during production of SAH was minimal, mean value of 7.2 mmHg and ICP slowly returned to the basal level within 30 minutes. Rats were divided into 3 groups; rats 2 hours (SAH-2h, n = 7) and 48 hours (SAH-48h, n = 7) after production of SAH and rats 2hours after 0.04 ml saline injection for control (Control, n = 7). LCGU was studied according to the methods developed by Sokoloff.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Augmented enkephalin-immunoreactivity in adrenaline-producing phaeochromocytomas.

Immunohistochemical studies for methionine- and leucine-enkephalin were performed on 26 phaeochromocytomas to elucidate the patho-physiological roles of enkephalins. Positive reactions were seen in all phaeochromocytomas with varying intensities. The location of methionine- and leucine-enkephalin agreed fairly well with each other. Stronger immunostaining was obtained in phaeochromocytomas secreting both adrenalin and noradrenaline than in those secreting predominantly noradrenaline. Paroxysmal hypertension was frequently observed in patients with adrenalin-secreting phaeochromocytomas, especially those with marked enkephalin positivity. Urinary excretion of metanephrine was significantly correlated with enkephalin positivity. These findings show that all phaeochromocytomas retain the ability to produce enkephalins of the adreno-medullary or extra-medullary chromaffin tissues from which they derive. Augmented enkephalin-immunoreactivity in adrenalin-producing phaeochromocytomas may be interpreted as reflecting a close association of enkephalins with adrenalin under physiological conditions.

Adrenal Gland Neoplasms↗
PubMed1990

Studies on subtype composition in natural leukocyte interferon preparations.

Antisera raised against partially purified human leukocyte interferon in goat and horse were exhaustively adsorbed and purified. Affinity chromatography using these antibodies gave 10,000-fold purification in one step without losing interferon activity. Then enzyme immunoassay was established with these antibodies and utilized for subtype analysis. Crude and affinity purified leukocyte interferons showed identical profiles of antiviral activity and immunoreactivity when fractionated by means of reversed phase high performance liquid chromatography. These results suggested the possibility of providing mixture of subtypes of leukocyte interferon occurring in natural host response, with comparable purity of recombinant ones.

Animals↗
PubMed1990

Fetal hypothalamic brain grafts to the ventromedial hypothalamic obese rats: an immunohistochemical, electrophysiological and behavioral study.

Fetal ventromedial hypothalamic (VMH) tissue was transplanted into or around the third ventricle of adult Fischer 344 rats to determine if transplanted VMH tissue could reverse the hyperphagia and obesity produced by bilateral VMH electrolytic lesions. Host VMH-lesioned rats received stereotaxic implants of 13 to 19 postcoitus fetal VMH tissue from normal Fischer pups. The results show that: 1) Fetal VMH tissue survived in the brain (mainly in the third ventricle) of VMH-lesioned rats. The optimal survival and differentiation was at the gestational age of 13 days; 2) VMH-lesioned rats containing VMH grafts tended to consume less food than the controls, but this was not statistically significant. Neural grafts that could compensate the hyperphagia and obesity produced by the VMH lesions (in comparison to the controls) were those placed into the third ventricle; 3) Electrophysiological evidence demonstrated that VMH grafts contain glucoreceptor neurons in grafts not only located in the third ventricle, but also in the thalamus; 4) Immunohistochemical evidence showed the presence of serotonin, beta-endorphin and substance P immunoreactive fibers in the grafts. These results indicated that transplants of fetal VMH tissue in the brain of bilateral VMH-lesioned adult rats may have some functional effects (depending on the location of the graft).

Action Potentials↗
PubMed1990

Low-threshold calcium current in isolated Purkinje cell bodies of rat cerebellum.

1. The low- and high-threshold Ca2+ currents were observed in Purkinje cell bodies isolated from the cerebellum of newborn (2 wk old) and adult (8 wk old) rats under whole-cell clamp. A transient Ca2+ current (low-threshold or "T-type" ICa) was elicited by depolarizing step pulses to -60 mV or more positive potentials from a holding potential (VH) of -100 mV. In cells dissociated from newborn rats, a long-lasting Ca2+ current (high-threshold or "L-type" ICa) was also elicited by depolarizing command pulses beyond -30 mV. 2. The low-threshold ICa was resistant to the "washout" effect during the internal perfusion, whereas the high-threshold ICa faded gradually with time during the continuous internal perfusion. 3. In the current-voltage (I-V) relationship, the low-threshold ICa had a threshold potential around -60 mV and reached the maximum inward current around -20 mV. The activation and inactivation kinetics of the current depended on membrane potential: for a test-potential change from -60 to +40 mV, the time to peak of the current (activation) decreased from 31.9 to 5.0 ms, and the time constant of current decay (inactivation) decreased from 78.5 to 22.9 ms. 4. Steady-state inactivation of low-threshold ICa was membrane-potential dependent, and the inactivation of the 50% level was -79 mV. Recovery time constant from steady-state inactivation varied depending on the membrane potential. The time constants were 3.3 and 2.5 s at VHs of -100 and -120 mV, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Relationship between the occurrence of late potential and the location and size of myocardial infarction evaluated by thallium-201 SPECT].

High-frequency, low amplitude signals, late potentials (LPs), in the terminal portion of the body surface QRS of the signal-averaged ECG were frequently observed in ventricular tachycardia (VT) following myocardial infarction (MI). In this study, we evaluated the correlation between the occurrence of LPs and the size and location of MI estimated by Thallium-201 myocardial SPECT in 30 MI patients. The positive LPs were identified by the value of %RMS 40, the percent ratio of the root mean square voltage in the last 40 msec of the QRS complex to that of the total filtered QRS from the signal averaged ECG using bipolar X, Y, Z leads. The spatial distributions of LPs were evaluated by the LP30 area maps obtained by the body surface mapping using forty-five unipolar electrodes. Sixty projections were obtained over 180 degree by rotating gamma camera after 5 minutes intravenous injection of 74 MBq of Thallium-201. After low-pass filtering, images were reconstructed into short-axis, horizontal long-axis and vertical long-axis tomograms. The maximum count circumferential profiles for each short-axis cuts were generated from the apical to basal cut and they were expressed into two-dimensional polar functional maps (apex to the center), Bull's-eye map, to represent myocardial Tl distribution. Normal limits of myocardial Tl distribution were established as the mean minus 2 standard deviation from those of normal subjects. The MI size was estimated as defect volume ratio (DVR), the percent ratio of abnormal region to that of total volume of left ventricle. Significant differences in DVR were observed among MI with LPs and without LPs.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗
PubMed1989

Acetylcholine causes nicotinic depolarization in rat dorsal motor nucleus of the vagus, in vitro.

Action of acetylcholine (ACh) on the electrophysiologically identified preganglionic neurons in the dorsal motor nucleus of the vagus (DMV) were investigated in slice preparations of rat medulla oblongata by using conventional intracellular recording technique. Applications of ACh to the DMV neurons resulted in a marked depolarization, which was not abolished in Ca-free superfusing solution, indicating the direct action of ACh on the cells. This depolarization was associated with an increase in membrane conductance and markedly reduced in the Na-free superfusate. The extrapolated reversal potential of ACh response was about -35 mV, indicating that both sodium and potassium conductances are likely responsible for the ACh depolarization. Application of nicotine caused similar depolarization to that of ACh, while muscarinic agonists (muscarine and oxotremorine) did not have any effect. Additions of the nicotinic antagonists hexamethonium and D-tubocurarine to the bathing solution reversibly attenuated the ACh-induced depolarization, while the muscarinic antagonist atropine did not have any effect. The nicotinic properties of ACh action in the DMV neurons presented here form a striking contrast to previous autoradiographic findings. Though endogenous cholinergic inputs to the DMV have not been identified, ACh may have a strong influence on vagal control by depolarization through nicotinic receptors of the DMV preganglionic neurons.

Acetylcholine↗
PubMed1989

Developmentally different onset of alpha 1- and alpha 2-adrenergic responses in the neonatal rat dorsal motor nucleus of the vagus in vitro.

Development of noradrenergic responses in the rat dorsal motor nucleus of the vagus (DMV) from postnatal days 0 to 22 was studied by a conventional microelectrode technique using brain slice preparations. Between postnatal days 0 and 6, noradrenaline (NA) caused only alpha 1-adrenoceptor-mediated depolarizations. By postnatal day 14, alpha 2-adrenoceptor-mediated hyperpolarization appeared. During the next postnatal week, the response pattern to NA became similar to that in adults, including both alpha 1- and alpha 2-adrenergic responses. These results suggest that alpha 2-adrenergic responses in DMV neurons are absent at birth but develop rapidly in the 3 weeks after birth. Furthermore, alpha 1-adrenoceptors have already been functioning in the fetal period.

Action Potentials↗
PubMed1989

[Pharmacological effects of reiousan on experimental hepatic injuries and hepatic functions].

Pharmacological effects of Reiousan, a crude drug preparation consisting of bezoar and ginseng, on experimental hepatic injuries and hepatic functions were studied. After administration of Reiousan, carbon tetrachloride, d-galactosamine and alpha-naphthylisothiocyanate-induced experimental hepatic injuries in rats were inhibited. Facilitation of recovery from increased retention rate of sulfobromophthalein in hepatectomized rats, increase in hepatic blood flow, inhibition of superoxide anions, and decrease in blood ethanol concentration in rats administered ethanol were observed after application of Reiousan. Inhibitory effects of Reiousan on experimental hepatic injuries may result from the increase in hepatic blood flow and inhibition of superoxide anions.

1-Naphthylisothiocyanate↗
PubMed1989

Study of stomach cancer in atomic bomb survivors. Report 1. Histological findings and prognosis.

For the purpose of studying the histological findings and prognosis of stomach cancer in atomic bomb survivors, a histological diagnosis of 600 cases of stomach cancer observed between 1964 and 1986 in three medical institutions in Hiroshima City was made by a single pathologist and, furthermore, analysis of 231 cases thereof was performed using the DS86 dose estimated by the Radiation Effects Research Foundation. 1) By histological type of stomach cancer, the frequency of poorly differentiated adenocarcinoma (poorly differentiated adenocarcinoma and signet ring cell carcinoma) was significantly higher in the 1 rad or more group (average stomach organ dose of 30.6 rad) than in the 0 rad group. 2) As for stromal type, the frequency of scirrhous type was significantly higher in the 1 rad or more group, but no difference in infiltrative behavior could be demonstrated. 3) Early cancer tended to be observed at a low rate in the 1 rad or more group. 4) As for average survival time, of the early cancers only well differentiated adenocarcinoma showed a significantly lower survival time in the 1 rad or more group when compared to the 0 rad group.

Adenocarcinoma↗
PubMed1989

Acute and late effects of A-bomb radiation studied in a group of young girls with a defined condition at the time of bombing.

Ninety girl students have been identified, who were 14-15 years old when exposed to the atomic bomb while at the Central Telephone Office in Hiroshima located at a distance of 550 meters from the hypocenter. The mortality rate of the students exposed on the second floor of the building was estimated to be 50.9% and those exposed on the first floor (ground level) 33.3%. Doses to the students exposed on the second floor were estimated from cytogenetic evidence to be around 6 Gy in the T65 Dose system or appear to be 4 Gy in the DS86 system. These data indicate that LD50 is around 4 Gy in these young females. Among 28 students who were confirmed to be alive in 1965 and followed to the end of 1988, six students had breast cancer, mostly of invasive ductal type carcinoma. The incidence of breast cancer in the adolescent group was very high, the relative risk being 23.1 with 95% confidence limits of 12.9 to 42.2.

Adolescent↗
PubMed1989

Monoclonal antibodies specific for high molecular weight form of human epidermal growth factor.

Hybridomas that secrete monoclonal antibodies specific for the high molecular weight (HMW) form of human epidermal growth factor (hEGF) were established by fusing spleen cells obtained from mice immunized with purified urinary HMW-hEGF with myeloma P3 x 63Ag8.653. The resulting monoclonal antibodies were characterized basically into two groups. One group recognized both EGF and HMW-hEGF, while the other recognized HMW-hEGF specifically on radio immunoprecipitation. Surprisingly, the majority of the isolates was positive by western blotting. Utilizing these monoclonal antibodies for affinity chromatography, we purified HMW-hEGF successfully from urine. These antibodies may be an extraordinarily powerful tool for histological study related to both forms of EGF.

Animals↗
PubMed1988

Internal and external information processing by lateral hypothalamic glucose-sensitive and insensitive neurons during bar press feeding in the monkey.

Single neuron activities in the lateral hypothalamic area (LHA) were recorded during bar press feeding task in the monkey. First registered neurons were sorted into 2 groups, glucose-sensitive (GS) and glucose-insensitive (GIS) neurons, depending on their glucose sensitivity. The firing variations to feeding, electrophoretically applied catecholamines and opiate, and to odor and taste stimuli were investigated. GS neurons responded to dopamine, noradrenaline and morphine more often than GIS neurons. In feeding task GS neurons responded during bar press (BP) and reward (RW) periods with long-lasting inhibition of firing and at cue tone (CT) with transient inhibition, while GIS neurons responded during BP and RW periods mainly with excitation and at cue light (CL) with excitation. A majority of GS neurons responded to both odor and taste stimuli more often than GIS neurons. Data suggest that these two kinds of neurons in the LHA may be involved in different functional aspects of feeding: GS neurons, mainly in internal information processing and reward mechanism, and GIS neurons, in external information processing and motor aspects.

Action Potentials↗