Effects of high peak power microwaves on the retina of the rhesus monkey.

We studied the retinal effects of 1.25 GHz high peak power microwaves in Rhesus monkeys. Preexposure fundus photographs, retinal angiograms, and electroretinograms (ERG) were obtained to screen for normal ocular structure and function and, after exposure, as endpoints of the study. Histopathology of the retina was an additional endpoint. Seventeen monkeys were randomly assigned to receive sham exposure or pulsed microwave exposures. Microwaves were delivered anteriorly to the face at 0, 4.3, 8.4, or 20.2 W/kg spatially and temporally averaged retinal specific absorption rates (R-SAR). The pulse characteristics were 1.04 MW ( approximately 1.30 MW/kg temporal peak R-SAR), 5.59 micros pulse length at 0, 0.59, 1. 18, and 2.79 Hz pulse repetition rates. Exposure was 4 h per day and 3 days per week for 3 weeks, for a total of nine exposures. The preexposure and postexposure fundus pictures and angiograms were all within normal limits. The response of cone photoreceptors to light flash was enhanced in monkeys exposed at 8.4 or 20.2 W/kg R-SAR, but not in monkeys exposed at 4.3 W/kg R-SAR. Scotopic (rod) response, maximum (combined cone and rod) response, and Naka-Rushton R(max) and log K of scotopic b-waves were all within normal range. Retinal histopathology revealed the presence of enhanced glycogen storage in photoreceptors among sham (2/5), 8.4 W/kg (3/3), and 20.2 W/kg (2/5) exposed monkeys, while enhanced glycogen storage was not observed in the 4.3 W/kg (0/4) exposed group. Supranormal cone photoreceptor b-wave was R-SAR dependent and may be an early indicator of mild injury. However no evidence of degenerative changes and ERG depression was seen. We concluded that retinal injury is very unlikely at 4 W/kg. Functional changes that occur at higher R-SAR are probably reversible since we saw no evidence of histopathologic correlation with ERG changes. Bioelectromagnetics 21:439-454, 2000. Published 2000 Wiley-Liss, Inc.

Changes in whole-body metabolic parameters associated with radiation.

Continuous irradiation of experimental animals is an appropriate model for the research in space radiobiology. The onset and recovery of radiation injury can be estimated on the basis of the concentration/content of glycogen in liver, the phospholipid content in thymus and other radiosensitive organs and the triacylglycerol concentration in bone marrow. Further, the picture of the metabolism in irradiated organism may be completed by the analysis of serum glucocorticoid and thyroid hormone levels.

[Energy and plastic metabolism of the heart muscle in rabbits undergoing thyroid irradiation with decimeter waves]. / Energeticheskii i plasticheskii obmen serdechnoi myshtsy krolikov pri obluchenii shchitovidnoi zhelezy detsimetrovymi volnami.

The functional state of myocardial mitochondria, the glycogen and nucleic acid contents in myocardium, and morphometry of structural elements of cardiomyocytes and myocardial capillary network were investigated in order to select the optimal regimen of decimeter wave exposures with power density of 10, 120 and 240 mW/cm2 on the area of thyroid gland. It was shown that the thyroid gland exposure to decimeter waves at these intensities resulted in functional shifts in energy and plastic processes in myocardium and capillary blood supply. These changes increased to a considerable extent as the intensity of exposure was increasing and reached the maximum at power density of 240 mW/cm2 but event at this intensity there was not found the injurious effect of decimeter waves on the myocardium.

The regional distribution of glycogen in rat brain fixed by microwave irradiation.

Glycogen concentrations were measured by fluorescence enzymatic assay in rat brains fixed by focused microwave irradiation Regional glycogen concentrations varied 2.5 fold, ranging from 27.1 nmol glucosyl units/mg protein in the striatum to 52.3 nmol/mg protein in the cerebellum and 69.9 nmol/mg protein in the pons-medulla; other regions were intermediate in concentration. Since glycogen is contained primarily within astrocytes, this regional variation may reflect regional differences in astrocyte energy metabolism.

[Postradiation changes in the thyroid gland and skeletal muscle after exposure to iodine-131]. / Postradiatsionnye izmeneniia v shchitovidnoi zheleze i skeletnoi myshtse pri porazhenii organizma iodom-131.

The functional status of rat skeletal muscles was studied at dormancy and during the intensive muscular work under conditions of repeated administration of iodine 131 in doses causing reversible and irreversible damages to thyroid gland (the absorbed doses were from 0.27 to 266 Gy). The biochemical changes in muscles were transient; they correlated with the thyroid gland status and lifetime of animals and were displayed during the first 15 days and 2-12 months after the start of the isotope injection.

[Functional activity and metabolism of blood neutrophils exposed to low-intensity microwaves]. / Funktsional'naia aktivnost' i metabolizm neitrofilov krovi pri vozdeistvii mikrovoln maloi intensivnosti.

A 7 hrs exposure of white rats to power density (PD) of 500, 50 and 10 microW/cm2 for 30 days induced changes in phagocytic ability of blood neutrophils, glycogen content and alkaline phosphatase activity. At PD level of 500 microW/cm2 the depression of absorption and digestion functions of neutrophils as well as the decrease of alkaline phosphatase activity and glycogen content were observed during the whole period of aftereffect (three months after exposure). PD levels of 50 and 10 microW/cm2 caused intensification of phagocytic function and metabolism in neutrophils. By the end of the observation period the mentioned indices did not differ from the initial ones.

Metabolic changes after non-lethal x-irradiation of rats. I. Carbohydrates, hormones.

Male rats of the Wistar strain were fasted overnight prior to exposure to single total-body X-ray dose of 2.39 Gy (250 R). Irradiated and sham-irradiated rats were pair-fed for 5 days, in the next period they were fed ad libitum. The levels of corticosterone and immunoreactive insulin in serum, glucose in blood, glycogen in liver, heart and skeletal muscle were determined 1 and 6 h, 1, 2, 3, 7, 14, 28, and 38 days after irradiation and sham-irradiation. Irradiation of rats resulted, at one hour, in a decrease and, at two days, in an icrease in level of blood glucose. A marked increase in liver glycogen persisted from 6 h to 21 days after irradiation. The level of glycogen in the skeletal muscle was reduced at 6 h and increased on days 3 and 14. Heart muscle glycogen declined within the first 24 h and rose at 14 days after exposure. The kinetics of changes in the heart and skeletal muscle glycogen following non-lethal irradiation was similar and indicated an overlap of changes produced by fasting with those brought about by irradiation, particularly during the first week. Corticosterone in serum was markedly increased in rats at 24 and 72 h after irradiation compared to pair-fed controls. The serum insulin concentration did not change after irradiation, except for a single increase on day 21. Irradiation with non-lethal doses produced changes in the parameters of the carbohydrate metabolism studied, except for serum insulin, which reflected the changes in the nutrition regimen upon pair-feeding rather than the effect of ionizing irradiation.

Tissue glycogen and blood glucose in irradiated rats. I. Effects of a single lethal x-irradiation.

Fed and starved (overnight) male rats of the Wistar strains were exposed to wholebody irradiation with 14.35 Gy (1 500 R) of X-rays. After irradiation and sham-irradiation all animals were starved up to the examination performed 1, 6, 24, 48 and 72 h after the treatment. Concentration of glucose in the blood and concentration of glycogen in the liver, heart, skeletal muscle, brown and white adipose tissue were determined. Concentration of blood glucose and liver glucogen was found to increase between 1 and 6 h after irradiation of the starved animals. The most pronounced increase of glycogen concentration in the liver and heart muscle was observed 24 and 48 h after irradiation. The fed and starved irradiated rats reacted differently particularly between 48 and 72 h, when the liver glycogen concentration decreased in the fed animals and remained elevated in the starved ones. Very high values of terminal glycemia were observed in both groups. Accumulation of glycogen in the heart muscle indicates that this organ is sensitive to ionizing radiation.

Tissue glucogen and blood glucose in irradiated rats. II. Effect of non-lethal doses of continuous gamma-radiation.

Male rats of the Wistar strain were continuously irradiated with an exposure of 0.57 Gy (60 R) of gamma-rays from a 60Co source. Irradiation lasted from 1 to 50 days in an experimental field, in which control animals shielded from radiation were also placed. After a 16-h starvation, concentration of glucose in the blood and of glycogen in the liver and heart was determined 1, 3, 7, 14, 21, 25, 32, 39 and 50 days after the beginning of irradiation. Concentration of blood glucose in irradiated rats did not practically differ from that of control animals during the whole period of investigation. Concentration of liver glycogen in irradiated animals was higher than that of the controls during all time intervals, except for day 1. Values of glycogen in the heart muscle were approximately identical in irradiated and control rats, except for day 21, on which they sharply increased in the irradiated animals. In addition to the investigation of blood glucose and tissue glycogen during continuous irradiation, we followed these parameters immediately, and 1, 6 and 12 months after continuous irradiation with a daily exposure of 0.57 Gy (60 R) up to a total exposure of 14.35 Gy (1 500 R) of gamma-rays. Considerably higher values of liver glycogen were detected in irradiated rats immediately and 1 and 6 months after the end of irradiation.