Effect of gamma irradiation on the B vitamins of pork chops and chicken breasts

A study was made of the effect of low-dose gamma irradiation on the content of thiamine (B1), riboflavin (B2), niacin, pyridoxine (B6) and cobalamin (B12) in pork chops, and thiamine, riboflavin and niacin in chicken breasts. Gamma irradiation from a caesium-137 source was used to irradiate the samples in a range of 0.49 to 6.65 kGy from -20 to +20 degrees C. Over the range of dose and temperature studied it was possible to derive a mathematical expression for predicting the losses. A calculation was made of the effect of the loss of thiamine, riboflavin and niacin due to irradiation on the overall loss of these vitamins in the American diet. The losses of riboflavin and niacin were of the order of a fraction of a per cent. Pork is an important source of thiamine, but the calculated loss at 1.0 kGy of this vitamin in cooked pork was only 1.5 per cent. There were initial increases with radiation doses up to 2-4 kGy in the measured concentrations of riboflavin and niacin in both pork and chicken. The increases were highly significant, and are of concern both to the study of radiation effects and the chemical method of the determination of these two vitamins.     

The B-complex vitamins related to energy metabolism and their role in exercise performance: A narrative review

ObjectiveThe present review aims to clarify the relationship of thiamine, riboflavin, and niacin to exercise performance.NewsThe B vitamins thiamine (vitamin B₁), riboflavin (vitamin B₂), and niacin (vitamin B₃) are hydrophilic vitamins that play a fundamental role as coenzymes in enzymatic reactions of energy metabolism. The increase in energy demand during physical exercise can alter the requirements for these vitamins.Prospects and projectsThis study is a narrative review which selected and analyzed studies that investigated how the vitamins thiamine, riboflavin, and niacin can affect sports performance in both humans and experimental animal models.ConclusionThe research shows that supplementation with these vitamins does not necessarily produce ergogenic effects. Despite their fundamental roles in anabolic pathways, only the intake of thiamine-derivative substances showed some positive effects on exercise performance and fatigue. Isolated riboflavin supplementation did not show positive effects, while there is evidence that high niacin intake can harm exercise performance. Some studies found an increase in excretion and a decrease in the blood levels of these vitamins after exercise, but the results are inconsistent. However, different pharmacokinetics, doses or dosing frequency, and administration route of the supplemented substances can influence the results. There are few studies of B-vitamins and exercise, and most of them are not recent. New studies, with systematically controlled protocols, are necessary to elucidate the real effects of thiamine, riboflavin, and niacin in exercise performance.     

Radiolysis of α, α-trehalose in Concentrated Aqueous Solution; the Effect of Co-irradiated Proteins and Lipids

Summary

γ-Radiolysis (dose-rate: 0·89 Gy/s) or electron (e)-radiolysis (dose-rate: 5 × 10⁷ Gy/s) of unbuffered aqueous solutions of α,α-trehalose (concentration: 60 mg/ml, radiation dose: 20 kGy) at 0° C yielded glucose (G_γ = 1·7; G_e = 0·63) and 5-deoxyxylohexodialdose (G_γ = 0·21; G_e = 0·05). Buffering at pH-values of 5·0 or 5·5 and irradiation caused increased formation of these monomeric products, particularly of the deoxy-compound.

On addition of increasing amounts of bovine serum albumin or ovalbumin (10–30 mg/ml) and irradiation the yields of products were markedly reduced. The decrease in glucose formation was less pronounced when sperm whale myoglobin was present during γ- or electron-irradiation. The G-values of 5-deoxyxylohexodialdose, however, were increased by 45 per cent (γ-irradiation) and 70 per cent (electron-irradiation) at approximately 10 mg/ml of admixed myoglobin. Further increase in myoglobin concentration led to a gradual decrease in the yields of the deoxy-product. The observed effects are explained by scavenging of water radicals and by interactions of the added substrates with sugar radicals.

Emulsified lipids (palmitic acid methylester or trilinoleic glycerol) did not affect the radiation-induced formation of products from trehalose.     

Differences in the Acute Intestinal Syndrome after Partial and Total Abdominal Irradiation in Mice

Summary

The acute intestinal syndrome in mice was analysed after partial (PAI) and total abdominal irradiation (TAI). The LD_50/15 was significantly higher after PAI (16·3 Gy) than after TAI (14·3 Gy). The dose—response curve for maximal weight loss also showed a shift of 1·8–2 Gy to higher doses after PAI compared with TAI. The X-ray survival curve for duodenal crypt cells was shifted by only 0·6 Gy for PAI and TAI. In order to assess the possible role of radiation-induced leucopenia and the influence of irradiating the spleen (shielded with PAI), lethality, weight loss and blood leucocyte counts were comapred after PAI and TAI in splenectomized and non-splenectomized mice. No major difference in leucopenia was found between the different treatment groups, whereas the differences in lethality and weight loss between PAI and TAI remained the same. Shielding the spleen in the partial abdominal field therefore did not contribute to the difference in LD_50/15. These findings imply that the increased LD_50/15 after PAI compared with TAI was mainly due to shielding of a small part of the bowel (about 13 per cent of the abdominal area).     

Nutrition and Physical Performance

Physical training increases the nutrient requirements of total calories, proportion of carbohydrates, thiamine, riboflavin, niacin, iron, water, salt, and perhaps chromium. Conscious adjustments must usually be made in total calories, carbohydrates, water, salt, and iron consumption to maintain optimal performance levels. But thiamine, riboflavin, niacin, and chromium requirements should be met by simply eating more of a varied diet. Eating that promotes obesity, semistarvation, dehydration, and excess vitamin supplementation are counterproductive to physical training. The best pregame meal is normal, well-balanced, and based on the athlete's personal preferences, time of eating, and the competitive event.     

Rescue of Marker Phenotypes: Effects of BUdR Sensitization,Hypoxia and High LET

Summary

The survival curve of colony-forming ability of Chinese hamster wg3h cells has been compared with the dose—response curve for the expression of an active thymidine kinase (TK) gene from these cells. The TK⁺ phenotype was measured by hybrid colony formation after fusion of wg3h (TK⁺) cells with Chinese hamster A23 (TK^?) cells. The TK⁺ survival data fitted a multi-target curve up to 3 krad of ¹³⁷Cs irradiation, when a highly resistant fraction of hybrid colonies was seen at about 1 per cent survival. The D₀ of TK⁺ survival for the multi-target region was 3·1–4·0 times greater than that of wg3h survival, even when the D₀ for cell survival varied between 136 and 545 rad by 14 MeV neutrons and hypoxia respectively. This parallel modification of cell and TK⁺ sensitivities suggests that the lesions causing cell inactivation are of the same type as those that cause marker inactivation. Using 14 MeV neutron data the approximate target size for TK inactivation was calculated to be 0·54–0·91 per cent of the DNA content of the cell (or about one-fifth to one-tenth of a chromosome). The data support the idea that marker inactivation results primarily from damage occurring outside the marker gene. BUdR labelling of wg3h cells before irradiation caused slight toxicity (30 per cent reduction in plating efficiency) and a twofold increase in cell sensitivity. However, the sensitivity of the TK⁺ phenotype increases by only 30 per cent. The increased cell sensitivity thus appeared to result from synergism between increased sensitivity of DNA to strand breakage and metabolic toxicity, the latter being largely overcome by fusion with normal cells.     

Radiation Injury in Mouse Lung: Dependence on Oxygen Levels in the Inspired Gas

Summary

The relationship between radiosensitivity and the partial pressure of oxygen (PO₂) in the inspired gas has been established for radiation pneumonitis as a measure of lung damage following irradiation of the mouse thorax. The radiosensitivity at low PO₂ (0–1 per cent) fitted the linear transformation of the Alper, Howard-Flanders relationship giving a K value for lung tissue of 1·35 per cent oxygen with an oxygen enhancement ratio, m, of 2·13. The radiosensitivity at higher PO₂ (5–21 per cent) did not fit the Alper, Howard-Flanders relationship probably because the PO₂ of the inspired gas was greater than the PO₂ in the alveolus. At the low PO₂ levels in the inspired gas, back diffusion of oxygen from blood into the alveolus may lead to errors in the estimated value of K. If the low value of m is due to this ‘contaminating’ oxygen from blood then by taking a higher value for m, the amount of contaminating oxygen can be calculated (0·23 per cent) and a ‘true’ value for K (1·1 per cent) determined. Other uncertainties in this estimate of K due to the radiolytic consumption of oxygen and possible inadequacies in equilibration are discussed. Allowing for the uncertainties, it is concluded that the K value for lung damage lies towards the upper end of the range of K values measured for cells in vitro.     

The Effect of Unilateral Nephrectomy on the Subsequent Radiation Response of the Pig Kidney

Summary

The left kidney of 14 Large White female pigs, approximately 14 weeks of age, was surgically removed. Thirty weeks after unilateral nephrectomy (UN) the remaining kidney was irradiated with a single dose of between 11·9 and 15·6 Gy of ⁶⁰Co γ-rays; three pigs received sham irradiation. Following irradiation glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and haematocrit (Hct) were determined for up to 48 weeks after irradiation. Irradiation resulted in a dose-dependent decline in GFR, evident 8 weeks after irradiation. This was followed by a gradual improvement in GFR, although after doses of 14·0 Gy GFR remained below control values throughout the study. A similar pattern of response was seen in terms of ERPF, but this was not dose-related. Doses of ? 14·0 Gy also caused a significant reduction (p < 0·001) in Hct within 4–8 weeks. Minimal levels were evident 16 weeks after irradiation; Hct then increased, but remained below preirradiation values. Dose–effect curves were obtained by determining the percentage of irradiated kidneys which showed a ? 50% reduction in GFR and ERPF, fitted by probit analysis, and ED₅₀ values (± SE) were calculated for each parameter. The ED₅₀ values for GFR and ERPF were 14·49 ± 0·27 Gy and 12·56 ± 0·98 Gy, respectively. These values were not significantly different from those obtained from intact agematched pigs in which the right kidney alone was irradiated; UN did not compromise or alter the radiation response of the kidney to irradiation. However, the ED₅₀ values obtained for the UN pigs were significantly greater (p < 0·001) than the values of 9·76 ± 0·17 Gy and 6·19 ± 0·93 Gy, seen for GFR and ERPF in intact age-matched pigs in which both kidneys were irradiated. Thus although both experimental situations involved irradiating the entire renal tissue, the relative radiosensitivity of the kidneys varied considerably. These findings show that the radiosensitivity of the pig kidney can vary markedly, depending on the physiological status of the kidney at the time of irradiation.     

Products of radiation removal of lead from aqueous solutions

The influence of typical ·OH radical scavengers as potassium formate and isopropanol on the radiation-induced removal of lead was individually studied. The lead can be completely removed from aqueous solutions containing 1×10^?2 mol/L of formate already at the dose of 2.5 kGy. With increasing concentration of formate (5×10^?5–1×10^?2 mol/L) increases the amount of Pb(formate)⁺ species in the solution before irradiation. The radiation product is metallic lead at low concentration of formate to PbCO₃ at higher concentration of scavenger. In the system with 10% isopropanol dominates the species Pb²⁺ and the product of radiation reduction is then metallic lead.     

Abstracts of the Association for Radiation Research Winter Meeting,Leeds, 6–8 January 1988

Summary

A sensitive experimental design and data analysis were used to test rigorously whether the repair capacity in the skin of the mouse foot changes during a course of repeated 240 k Vp X-ray doses. Any such changes might reflect saturation or induction of repair enzymes resulting from progressive radiation damage, but most importantly this assumption of equal effect per dose fraction is central to all analyses of multiple-fraction radiation treatments, and remained to be demonstrated conclusively in skin. An X-ray dose of 2·5 Gy was given two, eight, 14 or 20 times with an interfraction interval of 8 h. Individual skin reactions for each mouse were analysed separately, giving 139 estimates of the effectiveness of 2·5 Gy (～ 35 in each of the four fractionation schedules). Regression analysis of effect per fraction versus number of fractions showed that there was no significant trend, i.e. the damage per fraction was constant regardless of the number of fractions used. The mean damage per fraction was 3·75 ± 0·15 per cent (95 per cent CL) of the full underlying damage equivalent to transient moist desquamation, and the slope of this plot was 0·0075 per cent ± 0·022 per cent (95 per cent CL) per fraction. It was concluded that the assumption of equal effect per fraction was not invalidated in mouse skin. Shorter interfraction intervals would not allow full repair between fractions, and this could be misinterpreted as a progressive loss of repair capacity in this type of experiment. This was tested in skin by giving 2·5 Gy doses two, eight and 14 times with a 1-h interfraction interval. Effect per fraction increased with number of fractions, by an extra 37 per cent from two to eight fractions and by a further 14 per cent from eight to 14 fractions, giving the illusion of loss of repair as predicted. This confirms the need to check that where loss of repair capacity is suspected, this is not due artifactually to incomplete repair between fractions in slowly repairing systems.     

Effects of Monoenergetic X-rays with Resonance Energy of Bromine K-absorption Edge on Bromouracil-labelled E. Coli Cells

Summary

In order to examine enhanced killing that might be induced by Auger cascades in the incorporated atoms in cells, bromouracil(BrU)-labelled E. coli cells were irradiated with monoenergetic X-rays at 13·49 and 12·40 keV, just above and below the K-absorption edge of bromine. In both cases BrU-labelled cells were more sensitive for killing than were normal cells. However, when the degree of BrU-sensitization was compared between the two energies of X-rays, the enhanced killing at 13·49 keV was only small, 2 ± 8 per cent based on the D₀ value in saline. By the addition of DMSO, which is believed to suppress radical-mediated effects, killing of BrU-labelled cells was enhanced at 13·49 keV by 8 ± 4 per cent as compared with 12·40 keV, based on D₀. These results have been examined in terms of absorbed energy in BrU-labelled cells and in terms of the number of induced Auger events.     

Post-irradiation Treatment with OK432 Can Prevent Radiation-induced Bone Marrow Death

Summary

The radioprotective effect of OK432, a Streptocuccus haemolyticus preparation, on bone marrow death was examined in mice. The LD₅₀ value was increased from 7·55 Gy in controls to 8·45 Gy in mice treated once with OK432 immediately after irradiation. Multiple administrations of the agent further elevated the LD₅₀ value to 9·56 Gy. The radioprotective effect was also apparent when multiple treatments were commenced as late as 72 h after irradiation.     

Partial Additivity of the Mitotic Delays Induced by Separate γ-irradiation of Sea-urchin Eggs and Sperm

Summary

Natural cell-mediated cytotoxicity (NCMC) by lymphocytes from Japanese atomic bomb survivors now living in the United States was measured. Seventy-one individuals were exposed to an estimated ‘0·00’ Gy (‘0 rads’) (S₀ group) and 58 to greater than ‘0·00 Gy’ (S₊ group) at the time of the bomb. Of this 58, 51 (88 per cent) received less than 0·50 Gy and 30 (52 per cent) received less than 0·10 Gy. NCMC was measured against ⁵¹Cr-labelled K562 target cells. Activity by lymphocytes from S₊ group donors was significantly greater than that for the S₀ group (p = 0·028 by the stratified Wilcoxon rank-sum test). This difference between the S₊ and S₀ populations was detected 35 years after exposure to the bomb. It is therefore feasible and important to examine appropriate biologic parameters to elucidate the effects of low doses of radiation in humans.     

Effect of Free Radicals Induced by Ultrasonic Cavitation on Cell Killing

Summary

The present study was undertaken to elucidate the mechanism of in vitro cell killing induced by 1·0 MHz continuous wave ultrasound at an intensity of 5·8 W/cm². The chemical effects and mechanical effects arising from acoustic cavitation were determined by the amount of liberated iodine and the number of DNA double-strand breaks, respectively. The survival of mouse L cells immediately after irradiation was estimated by counting the number of cells which are not stained by trypan blue and the clonogenicity of surviving cells remaining immediately after irradiation was monitored by colony-forming ability. The effectiveness of the dissolved gases in liberating iodine was in the order O₂ > Ar > N₂ > N₂O ～ 0. However, the effect of dissolved gases on the yield of double-strand breaks of DNA and on the two kinds of end points of cell killing was in the order O₂ = Ar = N₂ > N₂O ～ 0. These results suggest that the different amounts of free radicals induced by ultrasound are not directly related to the ultrasonically induced cell killing. The presence of cysteamine (2 mmol dm^?3) during sonication completely inhibited a decrease in clonogenicity of surviving cells, but did not inhibit that of cell survival immediately after sonication. These results suggest that the decrease of survival immediately after sonication is due to mechanical shear stress arising from cavitation, while the decrease of clonogenicity of the remaining surviving cells is due to free radicals induced by cavitation. The contribution of free radicals to total cell killing was estimated as about 1 per cent at the level of 95 per cent cell killing immediately after sonication.     

The Kinetics of Repair in Mouse Lung after Fractionated Irradiation

Summary

The kinetics of repair of sublethal damage in mouse lung was studied after fractionated doses of ¹³⁷Cs γ-rays. A wide range of doses per fraction (1·7–12 Gy) was given with interfraction intervals ranging from 0·5 to 24 h. The data were analysed by a direct method of analysis using the incomplete repair model. The half-time of repair (T_1/2) was 0·76 h for the pneumonitis phase of damage (up to 8 months) and 0·65 h for the later phase of damage up to 12 months. The rate of repair was dependent on fraction size for both phases of lung damage and was faster after large dose fractions than after small fractions. The T_1/2 was 0·6 h (95 per cent c.1. 0·53, 0·69) for doses per fraction greater than 5 Gy and 0·83 h (95 per cent c.1. 0·76, 0·92) for doses per fraction of 2 Gy. Repair was nearly complete by 6 h, at least for the pneumonitis phase of damage. To the extent that extrapolation of these data to humans may be valid, these results imply that treatments with multiple fractions per day that involve the lung will not be limited by the necessity for interfraction intervals much longer than 6 h.     

Synthesis of N'-methylnicotinamide in X-irradiated Rats

Summary

The influence of 600 r total-body x-irradiation on the formation and excretion of N'-methylnicotinamide (N'-MeNA) has been investigated. A significant increase in the urinary excretion of N'-MeNA (67·5 per cent) was observed after irradiation. Studies of the in vitro N'-MeNA synthesis in liver homogenates revealed that synthetic activity decreased by 19·0 per cent in irradiated rats killed 1 hour later. Addition of ATP or glutathione to the reaction medium could not restore the diminished N'-MeNA synthesis, suggesting that the immediate fall in the synthesis of N'-MeNA was probably due to impairment of the enzymes involved in this methylation process. In vitro N'-MeNA synthesis at 20 and 24 hours after x-irradiation, however, was increased by 32·2 and 52·8 per cent respectively. This was corroborated by in vivo studies, which showed 40·5 per cent rise in N'-MeNA synthesis in x-irradiated rats. The evidence presented seems to indicate that in addition to the radiochemical degradation of methionine, the acceleration of transmethylation processes may be responsible for the lowering of methionine levels in x-irradiated animals.     

The gamma-ray response of clear polymethylmethacrylate dosimeter radix RN15®

Basic characteristics of different batches of Radix RN15® dosimeter, a commercially available undyed polymethylmethacrylate dosimeter, was studied for its application to process control of radiation sterilization. Radix has relatively small deviation of thickness, optical absorption spectrum, and optical density values before irradiation. The response curves, in terms of net optical density per unit thickness (ΔOD/mm) as a function of absorbed dose, D_PMMA, are nearly linear up to 15 kGy and become sublinear at higher doses. Scattering of dose response in 5 dosimeter replicates is ± 1% (1 σ). The dose-response slope at 25 kGy while held at irradiation temperatures in the range 0–60°C, relative to those under 25°C, increases with temperature up to 40°C, the maximum point, and decreases at higher temperatures. Over the temperature range of 10–50°C, the variation with temperature of evaluated dose derived from the calibration curve at 25°C is less than 5% when using a dose rate of 6 kGy/h. At lower dose rates (e.g. 0.7 kGy/h) the irradiation temperature dependence is negligible over this temperature range. The temperature dependence at 40 kGy is less severe than that at 25 kGy. The post-irradiation stability of dose response is less than 5% for more than 100 h after 25 kGy irradiation and storage at 0–35°C. The change in optical density of unirradiated dosimeters 3 years after manufacturing is negligible when the dosimeters are stored at controlled laboratory conditions of temperature (25°C) and relative humidity (40%). The 3-year-old dosimeters by irradiation to a dose of 25 kGy show about 2% lower response than that at 25 kGy at the beginning of the 3-year period.     

The Effect of 238Pu α-particles on the Mouse Fibroblast Cell Line C3H 10T1/2: Characterization of Source and RBE for Cell Survival

Summary

Considerable interest has been aroused in recent years by reports that the transforming and carcinogenic effectiveness of low doses of high LET radiations can be increased by reducing the dose rate, especially for transformation of 10T1/2 cells in vitro by fission-spectrum neutrons. We report on conditions which have been established for irradiation of 10T1/2 cells with high LET monoenergetic α-particles (energy of 3·2 MeV, LET of 124 keV μm^?1) from ²³⁸Pu. The α-particle irradiator allows convenient irradiation of multiple dishes of cells at selectable high or low dose rates and temperatures. The survival curves of irradiated cells showed that the mean lethal dose of α-particles was 0·6 Gy and corresponded to an RBE, at high dose rates, of 7·9 at 80 per cent survival and 4·6 at 5 per cent survival, relative to ⁶⁰Co γ-rays. The mean areas of the 10T1/2 nuclei, perpendicular to the incident α-particles, was measured as 201 μm², from which it follows that, on average, only one in six of the α-particle traversals through a cell nucleus is lethal. Under the well-characterized conditions of these experiments the event frequency of α-particle traversals through cell nuclei is 9·8 Gy^?1.     

The Effect of Oxygen on the Sensitivity of Mammalian Tumour Cells to Neutrons and X-rays

Summary

Telophase abnormalities in Ehrlich ascites-tumour cells were observed 18 hours after the cells had been irradiated either with 1·5 mev x-rays or fast neutrons. The sensitivity of well-oxygenated tumour was greater than that of anoxic tumour by a factor of 2·5 in the case of x-rays, but of only 1·3 in the case of neutrons. After neutron-irradiation the abnormalities showed an exponential relationship to dose, but after x-irradiation the abnormalities increased more rapidly than the first power of the dose. When the proportion of abnormalities was 50 per cent the RBE in O₂ was 3·2, but in N₂ it was 6·5.     

Survival of HeLa Cells Cultured in Vitro and Exposed to Protracted Gamma-irradiation

Summary

Experiments are described in which S₃ HeLa cells were exposed to gamma-radiation at dose-rates of 9·5 and 19 rad/hour (chronic irradiation). The cell-survival, in terms of reproductive integrity, was compared with the same cell-line irradiated at 44·9 rad/min (acute irradiation). It was found that while a ‘type C’ multi-hit curve was necessary to describe the survival of cells irradiated at 44·9 rad/min, a simple exponential function of dose was sufficient to describe the survival at 9·5 and 19 rad/min. The data were compared with the results of Berry and Cohen (1962).