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Biomedical subjects

S Iwanami

Publications and source records attributed to S Iwanami.

At least 37 records · Page 2Linked to original sources
PubMed1985

Theory of survival of bacteria exposed to ionizing radiation. I. X and gamma rays.

A new model for the survival of bacteria exposed to ionizing radiation is constructed in the framework of a target theory based on microdosimetric concepts, where single- and double-strand breaks of DNA and their repair in vivo can be described consistently in terms of the microdosimetric quantity j (number of effective primary events per track per target). In this model, the ability of cells to repair DNA damage is taken into consideration in terms of the repair capacities for single- and double-strand breaks of DNA, xi 1 and xi 2 (0 less than or equal to xi 1, xi 2 less than or equal to 1). To apply this model to Escherichia coli K-12 strains with different repair abilities, values of the repair capacity for single-strand breaks, xi 1, were derived from experimental survival curves. The theoretical survival curves for 60Co gamma rays were found to be effectively insensitive to the value of xi 2. Experimental survival curves for the wild-type, uvr, and rec strains of E. coli K-12 were well reproduced in this model. From these results, it is concluded that the theoretical formulation for the survival fraction of bacteria can afford a quantitative method for analysis of the repair process for radiation-induced single-strand breaks in DNA in vivo.

Bacteria↗
PubMed1985

Deranged mineral content in the bone of patients with chronic renal failure, estimated by computed tomography.

To evaluate the extent of renal osteodystrophy in patients with chronic renal failure, the CT numbers of the lateral condylus and mid-shaft of the femur were measured. To adjust for variation due to measurement conditions, calibration phantom was simultaneously scanned with the femur. The CT numbers of the lateral condylus were significantly lower than the control in both nondialyzed (p less than 0.005) and dialyzed patients (p less than 0.05). The CT numbers of the mid-shaft of the femur in dialyzed patients correlated significantly to the duration of hemodialysis (r = 0.807, p less than 0.001). In 15 patients subjected to both CT scan and the photon absorptiometry, the CT numbers of the lateral condylus positively correlated to the mineral content of the radial (r = 0.57) and ulnar (r = 0.69) bones as calculated by photon absorptiometry. These results indicate that the CT scan can be used to estimate bone mineral content quantitatively, and is useful tool for evaluating renal osteodystrophy in patients with chronic renal failure.

Adult↗
PubMed1985

Deranged Ca, Al and Mg content in the tissues of patients with chronic renal failure, as measured by non-destructive neutron activation analysis.

Ca, Al and Mg content in the bone, aorta, skin and hair of 55 persons was measured by non-destructive neutron activation analysis. The Ca content in the bone of nondialyzed and dialyzed patients was found to decrease. Al and Mg were relatively higher than Ca in the patients compared to the controls. The present study suggests that fluctuation in the content of Al and Mg may have some relation to renal osteodystrophy such as osteomalacia as well as similar and related disorders. Al and Mg content in the aorta, and that of Ca in the hair of uremic patients, were higher than the controls. The mean Ca content in the skin of the patients was 25% higher than the controls. These findings indicate 1) that Al and Mg are possibly related to the advance of osteodystrophy, and 2) that Ca, Al and Mg deposits in the organs of uremic patients are a reflection of metabolic disorders in chronic renal failure.

Adolescent↗
PubMed1984

Trace element concentrations in hair, fingernails and plasma of patients with chronic renal failure on hemodialysis and hemofiltration.

Trace element concentrations in hair and fingernails and plasma of nondialyzed, hemodialyzed and hemofiltered patients with chronic renal failure and healthy volunteers were measured by atomic and flameless atomic absorption spectrophotometry and neutron activation analysis. Plasma aluminum concentrations in all three groups of patients were higher than in the controls. Aluminum levels in plasma and red blood cells were higher in hemofiltered patients than in dialyzed patients. The aluminum concentrations in the hair of both nondialyzed and dialyzed patients was higher than in the controls, while that in the hemofiltered patients it was not. These elevated aluminum concentrations appear to be mainly caused by the use of aluminum-contaminated dialysate. Calcium concentrations in the hair of nondialyzed and dialyzed patients were higher than in the controls. Plasma zinc concentrations in all the patients were lower than the controls, and the concentrations in hemofiltered patients were lower than in the dialyzed patients.

Adult↗
PubMed1984

Microdosimetric distributions for nanometer-size targets in water irradiated with 60Co gamma rays: frequency distributions of effective primary events by individual tracks of electrons.

A calculation method of frequency distributions for the microdosimetric quantity j (number of effective primary events per track per target), fj , is presented. fj distributions are calculated for nanometer-size targets in water irradiated with 60Co gamma rays, using degradation spectra of total electrons in water, phi t(E). Further, fractional total electron differential fluences effective to produce j effective primary events, phi t(E, j), are calculated. It is found that the frequency for occurrence of no effective primary event tracks (tracks traversing the target without any effective primary event inside the target) is very large for nanometer-size targets, and that the delta-ray effect on the fj distribution becomes more significant with the decrease of the target size and especially j effective primary events (j greater than or equal to 1) for very small targets are due mostly to delta rays.

Cobalt Radioisotopes↗
PubMed1983

Dopamine receptor system involving adenylate cyclase in canine caudate nucleus.

Two distinct dopamine binding sites, referred to as D1 and D2, exist in canine caudate nucleus, as characterized by [3H]dopamine binding to the synaptic membrane fraction. D1 has the low affinity for dopamine with the dissociation constant of a few micromolar, whereas the affinity for D2 is about two orders of magnitude greater. Classical neuroleptics such as haloperidol and chlorpromazine have no selectivity in the inhibition of D1 and D2 binding, whereas a number of 2-methoxy benzamide derivatives which have been synthesized in our laboratories exhibit rather different selectivity. Correlation between the selectivity of those benzamide derivatives for the two sites and the inhibition of apomorphine-induced stereotypy in rats suggests that D1 is more responsible for the stereotypy. Photoaffinity labeling of D1 and D2 with [3H]dopamine demonstrates that the two sites are distinct entities. In the D1 system, the adenylate cyclase which is responsive to Gpp(NH)p can be dissociable by the treatment with GTP-Sepharose into a guanine nucleotide binding unit and a catalytic unit which is insensitive to Gpp(NH)p. The catalytic unit restores the responsiveness to Gpp(NH)p after preincubation with the nucleotide binding unit. Furthermore, endogenous cAMP-dependent phosphorylation of two particular proteins (protein Ia and Ib) is shown, which may be at least partly responsible for stereotypy and dopamine turnover in the caudate nucleus.

Adenylyl Cyclases↗
PubMed1981

Synthesis and neuroleptic activity of benzamides. Cis-N-(1-benzyl-2-methylpyrrolidin-3-yl)-5-chloro-2-methoxy-4-(methylamino)benzamide and related compounds.

Three series of benzamides of N,N-disubstituted ethylenediamines (linear alkane-1,2-diamines), 1-substituted 2-(aminomethyl)pyrrolidines, and 1-substituted 3-aminopyrrolidines (cyclic alkane-1,2-diamines) were designed and synthesized as potential neuroleptics. All target compounds were evaluated for their inhibitory effects on apomorphine-induced stereotyped behavior in rats, and a good correlation between structure and activity was found throughout the series. In the linear series (analogues of metoclopramide), introduction of a benzyl group on the terminal nitrogen, rather than an ethyl group, and a methyl group on the p-amino group of metoclopramide both enhanced the activity. The resulting N-[2-(N-benzyl-N-methylamino)ethyl]-5-chloro-2-methoxy-4-(methylamino) benzamide(23) was about 15 times more active than metoclopramide. In the cyclic series, particularly among the benzamides of 1-benzyl-3-aminopyrrolidine, most of the compounds tested were more active than the corresponding linear benzamides. cis-N-(1-Benzyl-2-methylpyrrolidin-3-yl)-5-chloro-2-methoxy-4-(methylamino) benzamide (YM-09151-2, 55) was the most active among all of the compounds tested, being 13 and 408 times more potent than haloperidol and metoclopramide, respectively. Moreover, compound 55 exhibited a fairly high ratio of antistereotypic activity to cataleptogenicity compared with haloperidol and metoclopramide. It is expected that compound 55 may be used as a potent drug with few side effects in the treatment of psychosis.

Animals↗
PubMed1980

Disturbances of trace element concentrations in plasma of patients with chronic renal failure.

Plasma concentrations of 6 essential trace elements were measured in undialyzed and hemodialyzed patients with chronic renal failure (CRF) and in healthy volunteers by tube-excited X-ray fluorescence analysis and atomic absorption analysis. The influences of hemodialysis on plasma concentrations of Al, Zn, Cu and Br were also studied. High plasma concentrations of Al and Cu and low concentrations of plasma Zn were found in nondialyzed patients with CRF. Plasma concentrations of Al and Cu increased and Zn and Br decreased in the hemodialyzed patients with CRF. An elevated concentration of plasma Al may be primarily caused by permeation from dialysate across the dialyzer membrane. The use of water produced by reverse osmosis will prevent the elevation of plasma Al concentration in patients with CRF.

Adult↗