Shigeru Iwanami

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.

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.

Abnormal Accumulation of Vanadium in Patients on Chronic Hemodialysis Therapy

Vanadium (V) has been reported to inhibit a number of enzyme activities such as those of Na(+)-K(+)-ATPase. The main excretory pathway of this element is via the kidney. These facts led us to study the V distribution in uremic patients. As a result, hemodialysis patients at our dialysis center exhibited extremely high levels of serum V (23.9 +/- 11.3 ng/ml, n = 43) as compared with healthy adults. Nondialysis patients did not show increased serum V concentrations. The V contents were significantly elevated in the skin and in the aortae of hemodialysis patients. It was found that the tap water from Kanagawa prefecture, Japan, had the highest V concentrations among the 21 cities in Japan and the US. In conclusion, oral ingestion of V-contaminated water has likely caused an accumulation of the metal in patients with end-stage renal failure.

Theory of survival of bacteria exposed to ionizing radiation. 1. 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.

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.

Theory of relative biological effectiveness (RBE) of tritium β rays=bacteria killing effects of tritiated water

A new model is applied to bacteria exposed to tritiated water. In this model, the relation between the radiation quality, induction of single- and double-strand breaks in DNA and their repair in vivo can be reasonably described in terms of the microdosimetric distribution and the modification factors for single- and double-strand breaks in DNA. First, a mathematical formulation of RBE of tritium beta rays relative to an arbitrary reference radiation for killing effect on bacteria is derived on this model. Typical theoretical results on the survival curve parameters for bacteria exposed to tritiated water and RBE of tritium beta rays relative to 60Co gamma rays are presented. It is found that RBE of tritium beta rays depends on the ability of the cell to repair DNA damage. The present model is applied to the survival of Escherichia coli Bs-1 exposed to tritiated water and 7 MeV electrons. Although the average LET of tritium beta rays is remarkably higher than that of 7 MeV electrons, the experimental result that RBE of tritium beta rays relative to 7 MeV electrons is close to unity, is reasonably explained by the present model.

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 < 0.005) and dialyzed patients (p < 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 < 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.

Simple theory for the estimation of the mean absorbed dose in a cell in tritiated water

The authors formulate a simple theory for estimating the absorbed dose in the cell (Dc) for the cell in tritiated water, taking account of activity inside and outside the cell. They propose a method for determining values of weighting factor d for different shapes and sizes of cells. Finally, the specific feature of d and the usefulness of the method for the estimation of Dc, for the cell in tritiated water, are discussed.

Search for the Unknown Trace Element Abnormalities in Uremia

Deterioration of renal function produces various abnormalities, of trace element metabolism in the patients. The therapy of uremia such as an aluminum containing phosphate binder and hemodialysis also causes these abnormalities in the patients with chronic renal failure. These abnormalities could be an important causality of uremia.

Radiation Quality of Tritium β-rays: Microdosimetric Distributions for Nanometer-size Targets in a Medium Containing Tritiated Water

To elucidate the characteristics of the action of tritium beta-rays, the following parameters are derived: electron slowing down spectra of primary electrons (beta-rays) and delta-rays in a medium containing tritiated water; and frequency distributions for the microdosimetric quantity j (number of effective primary events per track per target), fj, for nanometer-size targets exposed to tritiated water. Features of the radiation quality of tritium beta-rays are discussed by comparing the present results with those for 60Co gamma-rays and 7 MeV electrons. It is concluded that, although tritium beta-rays, 60Co gamma-rays, and 7 MeV electrons are classified as the same low l.e.t. radiation, the radiation quality of tritium beta-rays is considerably different from those of 60Co gamma-rays and 7 MeV electrons, and has specific features such as a high average l.e.t., a small total electron fluence per unit absorbed dose, and a different microdosimetric distribution, fj, for nanometer-size targets.