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Biomedical subjects

K Saegusa

Publications and source records attributed to K Saegusa.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Intracavitary high dose rate afterloading irradiation of inoperable malignant bile duct obstruction].

After decompression of the bile duct with PTCD, seven patients with carcinomas of the bile ducts were submitted to an intracavitary Ir-afterloading irradiation performed according to the high-dose-rate method with a Buchler device. Most of the patients were irradiated with 30 Gy in two fractions. Five patients were also exposed to percutaneous radiation with 40 to 50 Gy. Local control was achieved in six patients. One patient developed a locoregional recurrence which was possibly due to a so-called "geographic miss". In one patient a benign fibrotic stenosis of the bile duct was found at the site of most intensive irradiation. Intracavitary irradiation is very important in the treatment of malignant obstruction of bile ducts. However, there is an urgent need of research with regard to the combined method with percutaneous irradiation and to the optimum fractionation of intracavitary high dose rate irradiation.

Aged↗
PubMed1985

The mode of action of 4-aminopyridine on the chronotropic and inotropic responses in the isolated, blood-perfused dog heart.

The effects of 4-aminopyridine (4-AP, 0.3 to 300 micrograms) on atrial rate and atrial muscle contractile force were investigated in the isolated, blood-perfused dog atrial preparation. Low doses (less than 30 micrograms) of 4-AP injected into the sinus node artery caused a dose-dependent positive inotropic response and a negligible positive chronotropic response. A higher dose (300 micrograms) of 4-AP induced a transient positive chronotropic response followed by a negative response and positive and negative inotropic responses. The negative cardiac responses to 4-AP were completely inhibited by an adequate dose of atropine and were potentiated by physostigmine. TTX or C6 suppressed partly, but significantly the negative responses induced by 4-AP. On the other hand, the negative responses to electrical stimulation (ES) were inhibited by atropine, C6 and TTX and those to ACh were blocked by atropine but not by C6 or TTX. The positive responses to 4-AP were not affected by propranolol but were potentiated by atropine. The positive inotropic response to 4-AP was significantly suppressed by a calcium channel blocker, diltiazem. From these results, it is concluded that the cardiac responses to 4-AP are composed of direct positive responses and negative responses which are related to activation of parasympathetic ganglionic neurotransmission.

4-Aminopyridine↗
PubMed1985

Potentiating effects of 4-aminopyridine on responses to intramural vagal stimulation in the isolated dog atrium.

The effects of 4-aminopyridine (4-AP) on the chronotropic and inotropic responses to intramural parasympathetic nerve stimulation and to injection of acetylcholine (ACh) into the sinus node artery were investigated after treatment with propranolol in the isolated, blood-perfused dog atrium. 4-AP (3-100 micrograms) induced positive chronotropic and inotropic effects and 300 micrograms of 4-AP induced biphasic, negative and positive effects. The negative responses to 4-AP were completely blocked by 10 micrograms of atropine. 4-AP (more than 30 micrograms) potentiated significantly the negative chronotropic and inotropic responses to intramural parasympathetic nerve stimulation at a frequency of 3-30 Hz. The potentiation of the responses to stimulation was greater at a low than at a high frequency of stimulation. Potentiation of the chronotropic effect was greater than that of the inotropic one. 4-AP in the doses used did not change the negative chronotropic and inotropic responses to injection of ACh into the sinus node artery. These results suggest that the potentiation by 4-AP of the cardiac responses to parasympathetic nerve stimulation was due to an increase in release of ACh from nerve terminals but not to an increase in responsiveness at the effector site.

4-Aminopyridine↗
PubMed1985

Suppression of strychnine on the chronotropic and inotropic effects in the isolated, blood-perfused canine atrium.

In the isolated, blood-perfused dog atrium, strychnine evoked dose-dependent decreases in atrial rate and contractile force, and the negative cardiac effects were not influenced by atropine. Strychnine suppressed dose-dependently the negative chronotropic and inotropic responses to intramural parasympathetic nerve stimulation, but not the response to acetylcholine. These results suggest that strychnine has direct cardiac depressant properties and inhibits the release of acetylcholine from parasympathetic nerve terminals in isolated dog atrium.

Acetylcholine↗
PubMed1984

Chronotropic, dromotropic and inotropic effects of dilazep in the intact dog heart and isolated atrial preparation.

When dilazep was administered intravenously to the anesthetized donor dog, mean systemic blood pressure was dose dependently decreased. At a dose of 0.1 mg/Kg i.v., the mean blood pressure was not changed but a slight decrease in heart rate was usually observed in the donor dog. At the same time, a slight but significant decrease in atrial rate and developed tension of the isolated atrium was induced. Within a dose range of 0.3 to 1 mg/Kg i.v., dilazep caused a dose related decrease in mean blood pressure, bradycardia in the donor dog, and negative chronotropic, dromotropic and inotropic effects in the isolated atrium. At larger doses of 3 and 10 mg/Kg i.v., dilazep caused marked hypotension, frequently with severe sinus bradycardia or sinus arrest, especially in isolated atria. When dilazep was infused intraarterially at a rate of 0.2-1 micrograms/min into the cannulated sinus node artery of the isolated atrium, negative chrono- and inotropic effects were dose dependently induced. With respect to dromotropism, SA conduction time (SACT) was prolonged at infusion rates of 0.2 and 0.4 micrograms/min. But at 1 microgram, dilazep caused an increase or decrease of SACT, indicating a shift of the SA nodal pacemaker. It is concluded that dilazep has direct negative chrono-, dromo- and inotropic properties on the heart at doses which produced no significant hypotension.

Animals↗
PubMed1984

[Evaluation of gamma camera collimator for regional cerebral blood flow measurements using a 133Xe inhalation method].

In the measurements of regional cerebral blood flow (rCBF) using inhalation of 133Xe gas, the activity present is generally limited in lower levels than those of usual brain scintigraphy. Measurements with low count-rate are usually resulted in diminishing the accuracies of results obtained. Therefore, it is necessary to make measurements using a high sensitive collimator for getting as much count-rate as possible when a gamma camera is used. The relationships among sensitivity and structures of multi-parallel collimator were mathematically analyzed. The results of analysis suggested that sensitivity usually increased by using a collimator with holes of reduced height and diameter. A prototype multi-parallel collimator with holes of low height and small diameter was made in our laboratory for testing sensitivity and resolution. The collimator possessing 1141 holes of 6 mm phi in hole diameter, 1.5 cm is hole height and septal thickness of 1 mm lead showed 24 times more sensitive than those of a general all purpose collimator supplied by the manufacturer. However, resolution measured in FWHM was of 9 to 14 mm at the collimator face and of 29 to 38 mm at 5 cm from the face. The results indicated that this collimator was useful enough in rCBF measurements with 133Xe inhalation using a gamma camera. The mathematical analysis however, suggested that optimum collimator for rCBF measurements was approximate 4.5 mm phi in hole diameter and 1.0 cm in hole height.

Adult↗
PubMed1982

[A clinical study on arthrography of the elbow joint (author's transl)].

There are many patients who visit a clinic with some complaints at the elbow joint. In such cases, it is customary to evaluate radiographs in making diagnosis. However, it is often difficult to interpret the X-ray films due to structural complexity of the elbow joint. Although in some cases arthrography is performed, there is neither standard technique nor standard method of projection established, hence the evaluation of the arthrogram is often quite difficult. The purpose of this paper thereby is to study the role of the arthrography of the elbow joint as a diagnostic tool second to plain X-rays. The technique must be simple and interpretation of it must be easy as well. It also should provide much diagnostic informations. The author firstly set a standard procedure of the elbow joint arthrography and a standard series of radiographic projections which suffice the above-mentioned conditions. Secondly, analysis of the procedure was done and the normal arthrograms were shown using cadavers. Thirdly, the author performed this procedure in 250 patients who have various disorders in the elbow joint. Finally, the clinical significance of this procedure as a diagnostic tool to elbow joint diseases was discussed. The results are as follows: 1. One ml of positive contrast medium in a child or 2 ml in an adult was injected through postero-lateral puncture of the radio-brachial joint. Three X-ray films--A-P, lateral, 45 degrees ulnar oblique--were obtained. 2. It was found that the arthrograms taken by this procedure can give informations which cannot be obtained by plain X-rays. 3. This procedure of arthrography is very useful as a diagnostic tool in many occasions i.e. in making correct diagnosis in trauma of children such as fracture, dislocation and ligamentous injury; in finding the existence, the location and the grade of synovitis; in finding the location and the size of a tumor; in finding the precise location of the abnormal shadow at the elbow joint; in deciding the level of the osteotomy in cubitus varus deformity; in evaluating derangement, tardy ulnar palsy and joint instability due to osteochondritis, etc. 4. By the analysis of the arthrograms in 250 patients it was shown that this procedure of arthrography gives significant clinical informations.

Adult↗
PubMed1982

[Induced radioactivities in treatment head of 10 MV X-ray linear Accelerator (author's transl)].

The concentration of 60Co and stable cobalt in the shellfishes and seaweeds which were collected from the coast around Japan were obtained by low background beta counting for 60Co and spectrometric determination of stable cobalt. The results obtained were as follows: (1) The 60Co was found in the shellfishes which were enriched in the stable cobalt. (2) The correlation between 60Co and stable cobalt was rather good in the shellfishes. (3) The activities of 60Co was found in the seaweeds taken from seashore near the nuclear power plant. (4) There was great differences in the specific activities between samples collected from contaminated and not contaminated area.

Gold Radioisotopes↗