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Biomedical subjects

H Suda

Publications and source records attributed to H Suda.

At least 235 records · Page 13Linked to original sources
PubMed1990

Molecular friction in an actomyosin molecular machine.

In muscle contraction, it has been widely recognized that a binding state exists between myosin and actin in the presence of Mg-ATP. To estimate the magnitude of binding strength, I introduce a concept of frictional phenomena which occurs between two sliding bodies in contact each other. In such cases, the sliding speed can be formulated as a function of the actin-myosin bond strength. In order to validate this, the present theory is applied for the two movement assay systems with no external load; one movement assay of Phalloidin Rhodamine bound F-actin on a myosin coated hydrophobic cover glass and another assay of myosin coated beads along actin cables of Nitella. If a coefficient of 0.005 is applied to the kinetic friction, 1pN for the sliding force per cross-bridge and 10 microns sec-1 for the sliding speed, it is found that the bond strength between actin and one myosin head is about 200 pN in the contracting state.

Actomyosin↗
PubMed1990

[Simplified intraarterial infusion and angiographic method for rabbit VX-2 hind limb tumor via the saphenous artery].

We developed a new simplified intraarterial infusion and angiographic method for rabbit VX-2 hind limb tumors. A 24 gauge cannula was placed in the saphenous artery of the tumor-bearing leg (not supplying the tumor) and used for intraarterial drug infusion or angiography. This method has several advantages as follows: 1) easy and time-saving in manipulation (about 15 minutes per a rabbit); 2) selective drug infusion into the tumor-supplying artery without fluoroscopy; 3) sequential follow-up angiographies available for weeks.

Animals↗
PubMed1990

[Intracavitary and interstitial hyperthermia with the 2 mm diameter microwave applicator].

Experimental and clinical studies were done on intracavitary and interstitial hyperthermia with a 2 mm diameter applicator with a 7 cm tip (Aloka, Co., Ltd.). Microwave energy at 2450 MHz was used to heat tumors. An outer cannula of 16G Medicut was implanted in the tumor. When a rabbit VX-2 tumor was heated, the temperature reached over 40 degrees C at 15 watts. We applied the same method to two patients, one with recurrent oropharyngeal tumor and the other with recurrent pelvic tumor. This applicator looks promising.

Animals↗
PubMed1990

Intraoperative ultrasonic imaging of the ascending aorta in ischemic heart disease.

In an attempt to locate any atherosclerotic lesion in the ascending aorta and to prevent embolization, intraoperative B-mode ultrasonography was performed in 100 patients with ischemic heart disease (31 women and 69 men). Ultrasonography was carried out with a 10-MHz probe placed directly on the ascending aorta. Ultrasonic imaging demonstrated an atherosclerotic lesion in the lower half of the aorta in 76 patients (76%), a lesion in the upper half of the aorta in 89 patients (89%), and a lesion at the orifice of the innominate artery in 99 patients (99%). Prospective palpation identified an atherosclerotic lesion in 12 (25%) of 48 patients. Thoracic computed tomography in 79 patients showed calcification in the lower half of the aorta in 6 patients (7.6%) and in the upper half of the aorta in 11 (13.9%). Palpation and thoracic computed tomography underestimated the frequency of atherosclerotic lesions. Intraoperative ultrasonography accurately identified atherosclerotic disease. This technique allows the surgeon to modify cannulation, aortic clamping, and operative technique to reduce the risk of perioperative stroke due to embolization of atherosclerotic debris from the ascending aorta.

Aorta↗
PubMed1990

Involvement of the entopeduncular nucleus and the habenula in methamphetamine-induced inhibition of dopamine neurons in the substantia nigra of rats.

The lateral habenula receives massive afferents from dopamine-rich forebrain areas through the stria medullaris and sends efferents to mesencephalic dopaminergic systems through the fasciculus retroflexus. In the present study, effects of electrolytic lesions of the habenula, transections of the stria medullaris, and kainic acid-induced lesions of the entopeduncular nucleus on methamphetamine-induced inhibition of substantia nigra dopamine neurons were investigated in rats. Following these lesions or transections the methamphetamine-induced inhibition on the dopamine neuronal activity was significantly attenuated compared to those in control animals with sham lesions or sham transections. Intravenous administration of methamphetamine at a dosage of 6.4 mg/kg produced only a 62.7 to 71.2% inhibition in lesioned or transected animals, whereas in control animals the activity of dopamine neurons was almost completely inhibited with this dose. The amounts of methamphetamine required to induce 50% inhibition of dopamine neurons in lesioned or transected animals was 3.3 to 4.7 times greater than those in control animals. There was no significant difference in cumulative dose-response curves between habenular-lesioned, stria medullaris-transected and entopeduncular-lesioned animals. These results, along with other findings, indicate possibly that the pathways running through the entopeduncular nucleus, the stria medullaris, the habenula, probably the lateral habenula, and the fasciculus retroflexus are involved in a feedback loop from the striatum to the substantia nigra and regulate the activity of dopamine neurons.

Animals↗
PubMed1990

BE-14348 substances, new specific estrogen-receptor binding inhibitors. Production, isolation, structure determination and biological properties.

Streptomyces graminofaciens BA14348, isolated from a soil sample, was found to produce new specific inhibitors of estrogen binding to its receptor. Five related substances, BE-14348A approximately E, were isolated, and their structures were determined by analyses of spectral properties. Of these substances, A was identical with the known flavanone, naringenin. On the other hand, B, C, D and E were all new compounds; the structure of B was determined to be 2(S): 3(S)-3-methyl-4',5,7-trihydroxyflavanone, C was a racemic mixture of 2(S): 3 (R) and 2(R): 3(S)-3-methyl-4',5,7-trihydroxyflavanone; D and E were 8-chloro derivatives of B and C, respectively.

Animals↗
PubMed1990

[Mitral valve replacement with preservation of ventricular annular continuity].

We evaluated clinical effects of mitral valve replacement with preservation of ventricular annular continuity in 53 patients with isolated mitral stenosis and regurgitation. The patients were divided into 3 groups; Group 1: the patients had conventional mitral valve replacement, Group 2: with preservation of posterior leaflet ventricular annular continuity (VAC) (33 patients), and Group 3: preservation of both anterior and posterior leaflet (8 patients). Operative technique was described for pure mitral regurgitation and mitral stenosis. There was one patient died within 30 days operatively in each group. In Group 1 the patient died for poor LV function, in Group 2, the patient died for postoperative GVHD, and in Group 3, the death caused by postoperative LV rupture. We have observed no late death. Minor thromboembolization in early stage were seen in 2 cases of Group 2 and there were no apparent correlation with operative technique. Postoperative cardiac catheterization data (Pulmonary Artery wedge pressure, C.O, LVEF, LVEDV1) showed no significant difference among these 3 groups. Segmental wall contraction in left ventriculography demonstrated good contraction in Group 2 and Group 3 compared with that of Group 1. Left ventricular contraction index with heart rate corrected mean Vcf (Vcfc) and left ventricular end-systolic wall stress (sigma es) relation using two dimensional cardiac echogram demonstrated almost normal range in the groups 2 and 3. These findings suggests that mitral valve replacement with preservation of ventricular annular continuity has beneficial effects on postoperative left ventricular function and requires to be further investigated.

Adolescent↗
PubMed1989

Relationship between length of longitudinal extension and maximal depth of transmural invasion in roentgenographically occult squamous cell carcinoma of the bronchus (nonpolypoid type).

This study was designed to verify our hypothesis that there are two different growth types in roentgenographically occult squamous cell carcinoma of the bronchus. Serial blocks prepared from the entire bronchial tree of 83 resected specimens of occult carcinoma were used for the evaluation of the relationship between the length of longitudinal extension and the maximal depth of transmural invasion. We prepared a length-depth diagram of 92 lesions, including multifocal carcinomas, which confirmed that there are at least two types: Most of these lesions are of the creeping type, which shows a marked superficial growth; the minority are of the penetrating type, which shows a marked downward growth. The diagram suggests that occult carcinoma has a propensity either for longitudinal growth along the bronchial lumen or for transmural growth into the bronchial wall at the time of occurrence. It is likely that the penetrating type grows rapidly and becomes advanced in a short time. Identification of longer lesions of the creeping type is occasionally problematical both at bronchoscopy and at surgical treatment. The stump is usually positive for carcinoma unless frozen sections or imprint specimens of the margin of resection are examined, because it is frequently difficult to identify the proximal end of extension by bronchoscopy.

Bronchi↗
PubMed1989

[Response properties of the neurons in the cervical cord to stimulation of the inferior alveolar nerve in the cat].

The purpose of this study was to investigate the neuronal mechanisms of the clinical symptoms of unusual muscle stiffness and/or pain in the neck and shoulder sometimes observed in patients suffering from chronic pulpal or periodontal diseases. Physiological properties of the neurons responding to the inferior alveolar nerve stimulation (inferior alveolar nerve driven-neurons: IANDNs) were studied by recording single unit activities in the upper cervical cord in cats anesthetized with alpha-chloralose. The results were as follows: (1) IANDNs were widely distributed from the dorsal horn to the ventral horn in the gray matter of the cervical cord (C2 and C3). (2) IANDNs were subdivided into two types of neurons based on the latencies of the spike responses: fast-type (F-type) (n = 60) and slow-type (S-type) (n = 101). (3) Two possible pathways from the inferior alveolar nerve to the cervical spinal cord participating in these spike responses were assumed: one was through the trigeminal spinal nucleus and the other through Probst's tract by way of the trigeminal mesencephalic nucleus. These results suggest that the impulses originating from dental inflammatory loci might drive IANDNs in C2 or C3 and that their activities may evoke contraction of the neck muscles, resulting in their stiffness and cervical back pain.

Animals↗
PubMed1989

[Oral dosage study of miporamicin administered during the period of fetal organogenesis in rats].

Experiments were conducted to assess the effects of miporamicin (MPM) on prenatal and postnatal development of fetuses and offsprings of rats receiving the compound at oral dosages of 40, 200, or 1,000 mg/kg/day during the organogenesis stage of gestation. The drug treatment had no appreciable effect on maternal body weight during pregnancy or lactation period. The rats showed decreased food intake and increased water intake during gestation period in the groups given greater than or equal to 200 mg/kg/day, and increased food and water intakes during lactation period in the group given 1,000 mg/kg/day. There was no macroscopic evidence of changes indicative of any effect of the treatment in the viscera of rat dams at terminal necropsy. Observation of the fetuses did not reveal any effect of the treatment with MPM with respect to the number of implantations, the number of living fetuses, the death rate of fetuses or incidence of external, visceral, or skeletal anomalies. Male fetal weights were low in the groups given greater than or equal to 200 mg/kg/day. Observation of the offspring post partum failed to disclose any abnormalities indicative of adverse effects of the treatment with respect to birth index, viability index, weaning index, postnatal external differentiation, body weight changes, external morphology, skeleton, viscera, organ weight, functional and behavioral tests, emotion, learning ability, or reproductive performance, or in respect of prenatal development of their fetuses (F2). It is concluded from the results that no effect dose levels of MPM was 40 mg/kg/day in rat dams, 40 mg/kg/day also for their fetuses, and 1,000 mg/kg/day for postnatal development of the offspring under the experimental conditions described.

Abnormalities, Drug-Induced↗
PubMed1989

[Pulmonary arteriovenous fistula (PAVF) diagnosed by two-dimensional Doppler echography].

We report a case of pulmonary arteriovenous fistula (PAVF) with efficiency of the two-dimensional doppler echography for clinical evaluation. A 23-year-old female admitted to our hospital for lips cyanosis, exertional dyspnea and abnormal round shadow by chest X-ray. The two-dimensional echography demonstrated an efferent artery and a drainage vein of the PAVF. Pulmonary arteriography confirmed the diagnosis of a solitary PAVF located in the S10 of the left lung. The fistula was enucleated successfully with the recovery of cyanosis and dyspnea.

Adult↗
PubMed1989

[Postoperative bronchopleural fistula--diagnostic significance of masked cases and results of early re-operation].

We studied recent-day cases of postoperative bronchopleural fistula from 1982 to 1985. And in 1985, postoperative chest X-ray films were intensively compared with previous ones. Radiological signs for bronchopleural fistula and/or alveolar fistula such as increases in air content and/or falls in air-fluid level of pleural space were seen in 11 (7.1%) of 155 pulmonary resection cases in 1985. Among them, 8 of these cases were confirmed as bronchopleural fistulas. So one half of cases with these radiological findings were bronchopleural fistulas. But 2 of these 8 cases were masked bronchopleural fistulas which were not recognizable by bronchofiberscope and soon or later, bronchopleural fistulas developed which were recognizable by bronchofiberscope. For differential diagnosis between the bronchopleural fistula and alveolar fistula, serial chest X-ray films which was compared with previous one, were useful. In masked bronchopleural fistula cases, abnormal findings as mentioned above were seen more than three times, but in alveolar fistula cases were seen less than two times. On the bronchoscopic examination, bronchopleural fistulas were mainly located at the side of the residual lobe on the stump. Bronchopleural fistula cases which were re-operated for re-amputation, re-suture, and coverage of the stump within 48 hours, were all cured. So we concluded early re-operation is the best choice for bronchopleural fistula patient, because of short administration, no cosmetical problems and no disadvantage for lung function.

Bronchial Fistula↗
PubMed1989

[Study of postoperative bronchopleural fistulas--analysis of factors related to bronchopleural fistulas].

Postoperative bronchopleural fistulas, although reduced in incidence, remain as a grave complication of pulmonary resection. In our department, cases of lung cancer have been rapidly increasing and those of infectious diseases have been decreasing. In light of this trend, the causes of bronchopleural fistulas may have changed, and thus we studied recent cases of postoperative bronchopleural fistulas from 1982 to 1986. Bronchopleural fistulas were seen in 5 (7.8%) of 64 cases of inflammatory diseases and in 19 (4%) of 481 cases of lung cancer. In lung cancer, bronchopleural fistulas were more frequently seen with advanced cases, especially in cases of residual tumors on the stump and in cases of intrathoracic use of anticancer drugs. The highest incidences of bronchopleural fistulas were seen with right pneumonectomy and right lower lobectomy. Bronchoscopic examination showed bronchopleural fistulas to be mainly located on the stump beside the residual lobe. When Sweet's procedure is employed, this is the point with the most tension on the stump. Clinical and retrospective analysis of preoperative data revealed the following factors to be significantly higher in cases of bronchopleural fistulas than in cases of non-bronchopleural fistulas: fever, use of steroid hormone, Haemophilus influenzae in sputum, elevation of erythrocyte sedimentation ratio and anemia. Such analysis of postoperative data showed the following factors to be significant: fever, use of steroid hormone, leucocytosis, tracheostomy and bronchoscopy for sputum suction.

Adolescent↗
PubMed1989

[A successful emergency operation of acute aortic dissection (DeBakey I) with aortic root rupture and right coronary avulsion].

We report a successful emergency operation for a patient of acute aortic dissection with cardiogenic shock. A 73-year-old man was admitted to our hospital with a complaint of severe chest pain. The emergency aortography and echocardiography demonstrated aortic dissection (DeBakey I) with aortic valve regurgitation and massive pericardial effusion. The emergency operation started 2 hours after the onset. We performed reconstruction of ascending aorta and aortic valve using composite graft, since the patient had aortic root rupture and right coronary avulsion. Subsequently, the right coronary bypass grafting of saphenous vein was performed in addition to the reimplantation of left coronary artery by carrel patch method. The postoperative course was uneventful and the patient remains asymptomatic.

Acute Disease↗
PubMed1989

[A case of miliary tuberculosis with intracranial tuberculoma].

A case of miliary tuberculosis with intracranial tuberculoma was reported. Homogenous or ring-like enhancing lesions surrounded with edema were seen after administration of contrast material on CT examination. However, CT is considered very useful method of evaluating the effect of antituberculous therapy.

Brain Diseases↗
PubMed1988

Habenular lesion attenuates methamphetamine-induced inhibition of dopamine neuronal activity in the substantia nigra pars compacta of rats.

The relation between the habenula and central dopaminergic system was investigated by examining the inhibitory effects of methamphetamine on the firing rate of dopamine neurons in the substantia nigra of habenular lesioned and unlesioned rats. Electrolytic lesions of the habenula attenuated the methamphetamine-induced inhibition of dopamine neurons in the substantia nigra. This, along with other findings, indicates possibly that the habenula is involved in a feedback pathway from the striatum to the substantia nigra and regulates the activity of dopamine neurons in the substantia nigra.

Action Potentials↗
PubMed1988

The friction constants of bundle-like particles in solution.

In our previous experimental work the following was found: an I-Z-I particle, having a bundle-like macromolecule composed of many thin filaments of actin, had a much larger rotational friction constant than that of a single sarcomere having a more compact bundle-like structure composed of not only actin but also myosin filaments. In this paper, the reason for such a large friction constant of I-Z-I is elucidated by a simple theory (based on the Helmholtz principle in hydrodynamics) in terms of the solvent permeability through the particles. It is demonstrated that if the filaments on the bundle surface are composed of flexible segments, each of which has a local Brownian rotation, the solvent-flow along the surface is strongly depressed because of increased energy dissipation and the solvent permeates through the bundle. The large friction constant of an I-Z-I is suggested to be due to this effect. This situation is very different from that of a single sarcomere without flexible filaments on the surface.

Actins↗