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Biomedical subjects

S Okajima

Publications and source records attributed to S Okajima.

At least 55 records · Page 3Linked to original sources
PubMed1991

Synthesis and antitumor activity of 20(S)-camptothecin derivatives: carbamate-linked, water-soluble derivatives of 7-ethyl-10-hydroxycamptothecin.

Novel 36 derivatives (6), bonding the phenolic hydroxyl group of 7-ethyl-10-hydroxycamptothecin (4) with diamines through a monocarbamate linkage, were synthesized and their antitumor activity was evaluated in vivo. The derivatives were soluble in water as their HCl salts with the E lactone ring intact and exhibited significant antitumor activity. One of the derivatives, 6-27 showed excellent activity against L1210 leukemia and other murine tumors. The structure of its hydrochloride trihydrate (CPT-11) was determined by spectroscopic and crystallographic methods.

Animals↗
PubMed1991

Changes in sodium-22 turnover and total body potassium in two-kidney, one-clip renovascular hypertension.

Changes in sodium-22 turnover and total body potassium (TBK) were studied during acute (within 2 weeks after clipping) and chronic (12-14 weeks after clipping) phases in two-kidney, one-clip (2k, 1c) hypertensive rabbits by using a whole body counter. Sodium-22 injected intravenously was eliminated more rapidly in hypertensive rabbits than in controls. The biological half-life (BHL) of sodium-22 was shorter in hypertensive rabbits during both acute (p less than 0.05) and chronic phases (p less than 0.001). A significant negative correlation was obtained between the BHL of sodium-22 and blood pressure (r = -0.588, p less than 0.05) in hypertensive rabbits. TBK decreased significantly at the chronic phase in hypertensive rabbits (p less than 0.05), while TBK showed no significant change in controls. Serum sodium and potassium did not change during the observation period. Increased plasma aldosterone concentration was observed during the acute phase in hypertensive rabbits. These results suggested that sodium retention was not a major factor in the acute and chronic phases of 2k, 1c hypertension in rabbits and that pressure natriuresis could explain, at least in part, the lack of sodium retention. Furthermore, there appears to be a derangement in the intracellular potassium metabolism which may be associated with the maintenance rather than the development of hypertension.

Aldosterone↗
PubMed1991

Physical dosimetry at Nagasaki--Europium-152 of stone embankment and electron spin resonance of teeth from atomic bomb survivors.

Gamma-rays from thermal neutron-induced radionuclide of 152Eu in rocks near the ground center of the atomic bomb (A-bomb) explosion (hypocenter) in Nagasaki were measured with a pure germanium semiconductor detector. Depth profiles of 152Eu activity were obtained for 22 core samples taken from stone embankments on both sides of two rivers (the River Shimono-kawa and the River Urakami-gawa) within 500 m of the hypocenter since the activity in the rocks has a history of incident neutron energy. although the activities of the surface sections were varied from sample to sample, the slopes of depth profile in rock and the value of 152Eu activity in the depth of 240-280 mm were similar among the samples taken from the same location. On the other hand, neutron penetrating experiments using both a fast and a thermal neutron reactor were performed to obtain the relationship between the incident neutron energy spectra and the depth profiles of 152Eu activity in rock. The depth profiles in the bomb exposed samples were close to that obtained by using a 10 mm polyethelene moderator in the reactor experiments. Electron spin resonance (ESR) measurements from teeth of A-bomb survivors were carried out to estimate the individual gamma-ray dose of the survivors. The absorbed dose of ten tooth samples was estimated by ESR dosimetry. The results of ESR dosimetry were consistent with the calculations of tissue dose in air of A-bombs and irradiated shielding configuration of individuals.

Electron Spin Resonance Spectroscopy↗
PubMed1990

Measurement of 239Pu in soil and plants in the Nishiyama District of Nagasaki.

Nishiyama district in Nagasaki is located approximately 3000 m east of the hypocenter of the atomic bomb that was dropped on 9 August 1945. This district is also known as an area where there was a concentrated radioactive fallout with the black rain that was carried by a westerly wind. The Nagasaki atomic bomb was a Pu bomb, and the fallout must have included 239Pu without fission in addition to fission products. The presence of 239Pu in Nishiyama district has been confirmed previously. In this study, the distribution of 239 + 240Pu concentration in the uncultivated soil and the transfer factor of 239 + 240Pu to agricultural products in Nishiyama district were examined. The concentration of 239 + 240Pu in the uncultivated soil was 20 Bq kg-1, which was approximately eight times as high as that in the control districts. The transfer factor of 239 + 240Pu to agricultural products was 10(-4) - 10(-3), which was 1/100-1/200 of that of 137Cs.

Agriculture↗
PubMed1990

[Mechanisms of reperfusion injury of rat kidney].

Recently, oxygen free radicals have appeared to play a major role in injury after ischemia, especially that followed by normoxic reperfusion. To clarify the mechanisms of reperfusion injury, the activities of both oxygen radical producing enzymes and radical scavenging enzymes were measured in the ischemic rat kidney followed by reperfusion. All defensive enzymes activities significantly decreased; superoxide dismutase 2.15 +/- 0.14----1.71 +/- 0.11, catalase 186.6 +/- 12.7----116.5 +/- 7.1, glutathione peroxidase 30.0 +/- 2.6----19.1 +/- 2.9, glutathione reductase 118 +/- 5.1----39.9 +/- 6.8 (U/mg protein). Conversion from xanthine dehydrogenase to xanthine oxidase was only 12% of total activity, and all of them were reversible type oxidase. However, it was suggested by the electron spin resonance method that the tissue xanthine oxidase freed of superoxide dismutase could produce oxygen free radicals. In conclusion, reperfusion injury is caused not only by the increase of oxygen free radicals but by the destruction of scavenging systems.

Animals↗
PubMed1989

Long-term tissue distribution and steady state activity ratios of 232Th and its daughters in rats after intravascular injection of Thorotrast.

To estimate the absorbed dose in the critical organs of Thorotrast patients, it is necessary to know not only the distribution and concentration of 232Th but also its daughter nuclides in the body. The present investigation was undertaken in order to clarify the long-term 232Th tissue distribution and steady state activity ratios between subsequent daughters in the critical tissues using about 30 Wister male rats, as a basis for estimating absorbed doses. The tissue distribution of thorium was examined by means of an autoradiography of the whole body and/or the gamma-ray spectrometry at various times during 2 to 24 months following injection. The concentrations of daughter nuclides in tissues were determined by repetitive gamma examination over a period from 1 hr to 35 days after being sacrificed. The data indicate (1) that approximately 90% of injected Thorotrast is retained in the body for a prolonged period, but about 50% of radium and 10% of radon produced from thorium are eliminated from the body, (2) that the mean steady state activity ratios of 224Ra and 212Pb to 228Th for liver are 0.56 and 0.28, and 0.54 and 0.16 for spleen, 0.58 and 0.82 for lungs, respectively, and (3) that the parent 228Th is translocated to the bone.

Animals↗
PubMed1988

The effect of pictorial context on sentence memory in Broca's and Wernicke's aphasia.

Eighteen aphasic patients (8 Broca's and 10 Wernicke's aphasics), 11 right hemisphere damaged patients and 12 normal subjects were tested to assess the effect of pictorial context on verbal memory with a sentence recognition task. The subjects were read aloud a stimulus sentence describing a simple event and simultaneously shown a picture congruent or incongruent with the sentence. Immediately following or after an interval of 30 sec, the subjects were read aloud a second sentence and asked to judge whether this sentence was the same or different from the stimulus sentence. The results indicated that verbal memory was better retained in supportive situations than in distracting situations, and that this contextual effect was greater in aphasic patients than in any of the other groups. Verbal memory declined rapidly after an interval in aphasic patients, but not in normal subjects. The Broca's and the Wernicke's aphasics demonstrated different performance patterns when semantic analysis of sentences was critical.

Aphasia↗
PubMed1987

Serum beta-enolase in acute myocardial infarction.

The enzyme beta-enolase (alpha beta and beta beta forms) is present in skeletal and heart muscle and catalyses the glycolysis of 2-phosphoglycerate to phosphoenolpyruvate. The enzyme was measured in serum samples from patients with acute myocardial infarction, angina pectoris, congestive heart failure, and idiopathic cardiomyopathy. Serum concentrations of beta-enolase were significantly increased in acute myocardial infarction but not in the other cardiovascular diseases. Activity peaked approximately 12 to 14 hours after an acute attack of chest pain, and then gradually decreased as the patient recovered. The rise and fall in beta-enolase concentration were faster and steeper than those of creatine kinase activity, particularly in patients in whom activities of both these enzymes were less high. The assay of beta-enolase, which is highly specific and sensitive, has considerable advantages for the early diagnosis of myocardial infarction and the diagnosis of a second episode of myocardial infarction because beta-enolase concentration increases very early and rapidly and clears quickly. These data imply that serum beta-enolase may be a more effective marker for early myocardial infarction, particularly in milder cases, than measurement of creatine kinase activity.

Adult↗
PubMed1987

Japanese patients with leukaemia following the use of Thorotrast including a patient with marked chromosomal rearrangements.

It is estimated that 20,000-33,000 persons have been injected with Thorotrast in Japan. By August 1984, 12 patients with leukaemia following the use of Thorotrast have been reported. Their clinical and haematological data indicate that most of the patients were males over 50 years of age and that the most frequent type of leukaemia involved the stem cells common to the granulocytic, erythroid and/or megakaryocytic lines. This assumption was supported by the evidence of marked chromosomal rearrangements in 100% of the cells from the bone marrow in our case. The median latent period from the administration of Thorotrast to the onset of leukaemia in Japan was 35 years, ranging from 16 to 45 years, which indicates that patients who were injected with Thorotrast should be carefully followed up in the future.

Acute Disease↗
PubMed1985

Mortality of registered A-bomb survivors in Nagasaki, Japan, 1970-1984.

A follow-up study of A-bomb survivors registered in Nagasaki was conducted from 1970 to 1984 by the Scientific Data Center of A-Bomb Disaster at Nagasaki University, which has collected medical and administrative data on A-bomb survivors with the help of Nagasaki City Hall and other organizations. The purpose of this study was to investigate the following two points. (1) Has the health screening program for A-bomb survivors reduced the mortality rate? (2) If so, how much has it reduced it, and what would the life-shortening effect of radiation be without the health screening program? The results revealed that the effect of radiation on mortality would be underestimated if the health screening factor were ignored. The estimated effect of radiation dose was compared with that estimated by the Radiation Effects Research Foundation (RERF).

Aged↗