Mortality reduction in mice administered a single abundant dose of zinc, manganese or magnesium after irradiation by gamma-rays at sublethal doses

Radioprotective effect has been observed in mice which have subcutaneously received a single dose of abundant inorganic zinc or manganese 24 hours before gamma-ray irradiation with a sublethal dose. Mechanism of the radioprotection has been suggested to be an abundant production of metallothionein (MT) induced by the metals. But process of the protection might be more complicated because immunological and hematopoietic functions are remarkably inhibited by the irradiation and many zinc binding-compounds with biological functions are known at present. Furthermore, the effect of these metals has been observed by the administration only before the irradiation. Radioprotective effect was shown in mice which were administered with not only zinc and manganese, but also magnesium. It seems that mechanism of the radioprotection of magnesium is different from that of zinc or manganese since magnesium is not known to induce MT production. It was observed that the relative concentration ratio of radioactivity in tissues and organs at 7th day (after injection of 65Zn) showed a marked difference between in irradiated and non-irradiated mice.     

Instrumental Neutron Activation Analysis of Trace Elements in Organs and Tissues of Zinc Deficient Mice

Eleven elements in ten organs and tissues of mice fed with Zn-deficient diet (Zn-def. mice) and those fed with control diet (control mice) were determined by INAA. Zinc concentrations in the organs of Zn-def. mice were not distinctly lower than those of control mice except for bone and pancreas, as similar to the predecessors' reported results. However, the Co content increased significantly in all the organs and tissues of Zn-def. mice compared with control mice. The organs and tissues observed were histologicaly normal and no typical symptoms of Zn deficiency disease were recognised. The results suggest that the change of Co-concentration may be regarded as a mark of the prestage for a Zn deficiency disease.     

UV-A induced oxidative stress is more prominent in naturally pigmented aged human RPE cells compared to non-pigmented human RPE cells independent of zinc treatment

To investigate the effects of zinc supplementation on human amelanotic (ARPE-19) and native pigmented retinal pigment epithelial cells (hRPE) under normal light conditions and after ultraviolet A light exposure. hRPE cells, containing both melanin and lipofuscin granules, were prepared from human donor eyes of 60-70 year old patients. Cells of the amelanotic ARPE-19 cell line and pigmented hRPE cells were treated with zinc chloride and subjected to oxidative stress by UV-A irradiation. Intracellular H(2)O(2) formation was measured using a fluorescence oxidation assay. Additionally, apoptosis and viability assays were performed. Control cells were treated identically except for irradiation and zinc supplementation. Under normal light conditions, zinc treated hRPE cells produced less H(2)O(2) than unsupplemented hRPE cells. Viability and apoptosis events did not change. After UV-A irradiation, ARPE and hRPE cells were greatly impaired in all tests performed compared to the non-irradiated controls. No differences were found after zinc supplementation. hRPE cells showed a higher apoptosis and mortality rate than non-pigmented cells when stressed by UV-A light. ARPE cells never showed any zinc related effects. In contrast, without irradiation, zinc supplementation reduced H(2)O(2) production in pigmented hRPE cells slightly. We did not find any zinc effect in irradiated hRPE cells. After UV light exposure, pigmented cells showed a higher apoptosis and mortality than cells lacking any pigmentation. We conclude that cells with pigmentation consisting of melanin and lipofuscin granules have more prooxidative than antioxidative capacity when stressed by UV light exposure compared to cells lacking any pigmentation.     

Determination of trace elements in hepatocyte of zinc deficient mice by means of INAA

Eleven elements in hepatocyte of mice fed with zinc deficient diet and those fed with control diet were determined by INAA. Zinc concentration, especially, in cytosolic fraction of zinc deficient mice was lower than that of control ones. On the other hand, cobalt concentrations in all fractions of zinc deficient mice were higher than those of control ones. However, when SDS-PAGE was performed for cytosolic fraction of hepatic cells, the positions and the number of the protein bands on gel developed for zinc deficient mice were not different from those for control ones.     

Uptakes of trace elements in Zn-deficient mice

A multitracer technique was used to obtain uptake rates of essential trace elements in various organs and tissues in Zn-deficient mice. A multitracer solution, containing more than 20 radioisotopes, was injected intraperitoneally into Zn-deficient state mice and control ones. Uptake rates of the radioisotopes were compared with concentrations of trace elements determined by instrumental neutron activation analysis (INAA) in order to study a specific metabolism of Zn and other essential trace elements, such as Mn, Co, Se, Rb, and Sr. The result suggests that Zn is supplied from bone to other organs and tissues and an increase in Co concentration in all organs and tissues depends on its chemical form, under the Z-deficient state.     

Methods for routine control of irradiated food: Determination of the irradiation status of shellfish by thermoluminescence analysis

In some countries, clearance has been given for treating certain types of shellfish by ionizing radiation in order to increase the shelf-life and to reduce health hazards which might be caused by contaminating microorganisms. In the present study, thermoluminescence (TL) analysis was used to examine the irradiation status of shellfish products purchased from local suppliers. For analysis minerals were isolated from the guts of the animals. Although on none of the examined products an irradiation treatment prior to analysis could be shown, the results obtained on non-irradiated and irradiated products have revealed that irradiation within the commercially used dose range can clearly be detected. Already first glow TL intensities of minerald indicated irradiation treatments. Normalized TL signals of non-irradiated and irradiated samples were clearly separated. By calculation of differences of TL intensities and TL signals between non-irradiated and irradiated samples in dependency of integration temperature an optimized integration area for glow curves was determined. The result of this study agree well with results obtained by two large-scale intercomparisons between food control laboratories to detect irradiation treatment of spices and herbal products as well as of fruit and vegetables by TL analysis of contaminating minerals.     

Effect of gamma irradiation on nutritional components and Cry1Ab protein in the transgenic rice with a synthetic cry1Ab gene from Bacillus thuringiensis

The effects of gamma irradiation on the transgenic rice containing a synthetic cry1Ab gene from Bacillus thuringiensis were investigated. There was almost no difference in the content of the major nutritional components, i.e. crude protein, crude lipid, eight essential amino acids and total ash between the irradiated grains and the non-irradiated transgenic rice. However, the amounts of Cry1Ab protein and apparent amylose in the irradiated transgenic rice were reduced significantly by the doses higher than 200 Gy. In vivo observation showed that Cry1Ab protein contents also decreased in the fresh leaf tissues of survival seedlings after irradiation with 200 Gy or higher doses and showed inhibition of seedling growth. The results indicate that gamma irradiation might improve the quality of transgenic rice due to removal of the toxic Cry1Ab protein.     

Tyrosine does not enhance tanning in pigmented hairless mice

Pre-tan products claiming to enhance pigmentation contain tyrosine as an‘active’ ingredient. Tyrosine is said to penetrate into the cell's metabolic pool, increasing the concentration of precursors essential to melanin formation, so that subsequent melanogenesis will be intensified. To address this theory, female pigmented hairless mice were irradiated three times weekly using FS-20 lamps while receiving 0.01% tyrosine or 0.01% glycine either as a diet supplement or topically daily for 4 weeks. Control groups received the supplement or topical application without irradiation. Two additional groups were treated with a commercial pre-tan enhancing product for 2 weeks prior to use of one group as a control, and the other irradiated as above. At the end of the experiment whole skin sections were taken for histological evaluation. Forward scattering absorbance spectrophotometry was performed on whole skin and separated epidermis. Comparison of averaged forward scattering absorbance spectra for each group revealed that there was no significant difference in the skin optics of any of the irradiated groups, while each irradiated group was significantly different from its non-irradiated control. The spectra of all treated controls fell within pre-established normal control limits. Histological evaluation by Fontana-Masson staining showed that all irradiated groups had developed noticeable pigmentation not present in the controls. Of the groups receiving topical applications, the irradiated tyrosine group developed strikingly less pigmentation than did the irradiated glycine group. The irradiated pre-tan product treated group was intermediate in the development of pigmentation. Melanocytes were visible throughout the dermis and epidermis of the irradiated groups, whereas only scattered dermal melanocytes were found in the controls. It appears that oral or topical tyrosine did not enhance pigmentation present with or without irradiation, detected optically or histologically.     

Identification of gamma-irradiated Chinese herbs by thermoluminescence analysis

The feasibility of thermoluminescence (TL) to differentiate irradiated Chinese medicinal herbs from non-irradiated was investigated. Thirty different dried Chinese herbs were tested, including root, flower, ramulus, rhizome, cortex, and whole plant samples. Irradiation of Chinese herbs was associated with strong TL peaks at ~150–250 °C, while TL curves of non-irradiated herbs had very low intensities above 250 °C, which was also confirmed by the TL ratio (non-irradiated, TL₁/TL₂ < 0.1). The ability to determine the irradiation dose by the TL method was influenced by the amount and types of minerals in the samples. All levels of irradiation doses could be detected when between 0.1 and 1.0 kGy, except for three herbs at 0.1 kGy dose. Different blends with small quantities (0.1–10 %) of irradiated herbs were also tested in this study. Samples with powder mixtures containing 1 % irradiated components could be differentiated (TL₁/TL₂ > 0.1) except for sterculia lychnophora, semen cassia, flos inulae, and anemone root. TL ratios of some herbs indicated irradiation (TL₁/TL₂ > 0.1) even if the irradiated components were as low as 0.1 %. Thus we demonstrated that TL analysis had excellent sensitivity and reliability for the identification of irradiated Chinese herbs.     

Feasibility of gamma irradiation as a stabilisation technique in the preparation of tissue reference materials for a range of shellfish toxins

The effect of γ-irradiation on concentrations of hydrophilic and lipophilic phycotoxins has been investigated by use of HPLC–UV and LC–MS. Pure toxins in organic solvents and toxins in mussel (Mytilus edulis) tissues were irradiated at three different doses. In solution all toxin concentrations were reduced to some extent. Most severe decreases were observed for domoic acid and yessotoxin, for which the smallest dose of irradiation led to almost complete destruction. For pectenotoxin-2 the decrease in concentration was less severe but still continuous with increasing dose. Azaspiracid-1 and okadaic acid were the least affected in solution. In shellfish tissue the decrease in toxin concentrations was much reduced compared with the effect in solution. After irradiation at the highest dose reductions in concentrations were between ca. 5 and 20% for the lipophilic toxins and there was no statistical difference between control and irradiated samples for azaspiracids in tissue. Irradiation of shellfish tissues contaminated with domoic acid led to a more continuous decrease in the amount of the toxin with increasing dose. The effect of irradiation on the viability of microbial activity in shellfish tissues was assessed by using total viable counting techniques. Microbial activity depended on the type of shellfish and on the pretreatment of the shellfish tissues (with or without heat treatment). As far as we are aware this is the first investigation of the effectiveness of irradiation as a technique for stabilising tissue reference materials for determination of phycotoxins. Our results suggest that this technique is not effective for materials containing domoic acid. It does, however, merit further investigation as a stabilisation procedure for preparation of shellfish tissue materials for some lipophilic toxins, in particular azaspiracids. Chemical structures of the toxins investigated in the study     

The effect of riboflavin-photoinduced degradation of alginate matrices on the diffusion of poly(oxyethylene) probes in the polymer network

The effect of irradiation, in the wavelength range of 310-800 nm, on the tracer diffusion of poly(oxyethylene) (POE) of different molecular weights embedded in various alginate matrices with the photosensitizer riboflavin (RF) present, has been investigated with the aid of pulsed field gradient spin-echo NMR (PGSE-NMR). Both alginate solutions of different polymer concentration were studied as well as corresponding acid gels of alginate produced by introduction of different amount of glucono-δ-lactone (GDL). In 2 wt.% alginate solutions, the values of the tracer diffusion coefficient suggest a strong obstruction effect as the probe molecular weight increases. Faster probe diffusion was observed for the irradiated samples, which indicates a photochemical scission of the polymer chains and the formation of a fragmented polymer network that facilitates the migration of the tracer chains. A semidilute alginate/RF solution was transformed into a gel by adding sufficient amount of GDL. GDL lowers the pH of the solution under the pK_a of alginate, favouring intermolecular associations and the evolution of a less homogeneous network with more open structure. Therefore, the POE chains were shown to diffuse faster in the acid gel matrix than in the corresponding more homogeneous alginate solutions. The photochemically induced cleavage again promoted faster migration of the probe chains in the irradiated samples. The probe diffusion of the eight-arm star-shaped POE sample revealed an augmented obstruction effect with increasing alginate concentration and higher values of the diffusion coefficient were found in gels. The evolution of a tighter network inhibits the diffusion of the probe molecules. At lower alginate concentrations the values of the tracer diffusion coefficients are higher for the irradiated samples than for the non-exposed systems.     

Effect of gamma irradiation on microbiological,chemical and sensory characteristics of licorice root product

Licorice root products were irradiated at doses of 0, 5, 10, 15 and 20 kGy in a ⁶⁰Co package irradiator. Irradiated and unirradiated samples were stored at room temperatures. Microbial population on product, chemical changes and sensory properties of produced solution of licorice root products were evaluated after 0 and 12 months of storage. The results indicated that gamma irradiation reduced the counts of microorganisms on licorice root products. D₁₀ of total count and klebsiella spp. were about 1.4 and 0.7 kGy, respectively. The mineral ions (Na, Ca and K) concentration in solution produced from irradiated products were lower than non-irradiated ones. Glycyrrhezinic acid and maltose concentration in solution produced from irradiated products were higher than non-irradiated ones. Sensory evaluation indicated that no significant differences (P<0.05) were found between solution produced from irradiated and unirradiated products in color, flavor, texture, or taste.     

Thermoluminescence detection of Korean traditional foods exposed to gamma and electron-beam irradiation

Thermoluminescence(TL) analysis was applied to detect irradiated Korean traditional condiments and soup mixes containing salt(NaCl). These food items, which are commercially irradiated in Korea, showed a consistently high correlation(R²) between the absorbed doses and the corresponding TL responses. It was proved that table salt played a role as an in-built indicator in TL measurements and its concentration in test samples was proposed as a correction factor for varying conditions of TL measurements. Pre-established threshold values were successfully adopted to identify 167 coded samples of Ramen soup mixes, both non-irradiated and irradiated with gamma and electron-beam energy. The TL intensity of irradiated soup mixes decreased with the lapse of time, but was still distinguishable from that of the non-irradiated samples at the fourth month of ambient storage. Expected estimates of absorbed doses, 2.85 and 4.75 kGv were obtained using a quadratic equation with average values of 1.57 and 4.90 kGy, respectively.     

Quality of fresh-cut Iceberg lettuce and spinach irradiated at doses up to 4 kGy

Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4 kGy. After irradiation, the samples were stored for 14 days at 4 °C. O₂ levels in the packages of fresh-cut Iceberg lettuce decreased and CO₂ levels increased with increasing radiation dose, suggesting that irradiation increased respiration rates of lettuce. Tissue browning of irradiated cut lettuce was less severe than that of non-irradiated, probably due to the lower O₂ levels in the packages. However, samples irradiated at 3 and 4 kGy had lower maximum force and more severe sogginess than the non-irradiated control. In addition, ascorbic acid content of irradiated lettuce was 22–40% lower than the non-irradiated samples after 14 days of storage. The visual appearance of spinach was not affected by irradiation even at a dose of 4 kGy. Consumer acceptance suggested that more people would dislike and would not buy spinach that was treated at 3 and 4 kGy as compared to the non-irradiated sample. Overall, irradiation at doses of 1 and 2 kGy may be employed to enhance microbial safety of fresh-cut Iceberg lettuce and spinach while maintaining quality.     

UVA- and UVB-induced changes in collagen and fibronectin biosynthesis in the skin of hairless mice.

The modifications induced in hairless mouse skin by chronic UV irradiation were investigated. Skin explant cultures were used to study UVA- and UVB-induced changes occurring in interstitial collagen (type I and type III) and fibronectin biosynthesis. To study the long-term effects, albino hairless mice were irradiated with UVA radiation alone from two sources with different spectral qualities or with UVB. UVA and UVB radiation produced a significant increase in the ratio of type III to type I collagen (more than 100% for UVA-irradiated skin and about 60% for UVB-irradiated skin) accompanied by a significantly increased fibronectin biosynthesis (50% or more in all irradiated groups). Irradiation with either UVA or UVB alone had no significant effect on the total collagen synthesis and resulted in only a slight decrease in the total collagen content of the skin determined as hydroxyproline. This decrease was significant only in the case of the group irradiated with UVA (xenon) (decrease of 25%, expressed as micrograms of hydroxyproline per milligram wet weight). A significant decrease in collagen hydroxylation (expressed as radioactive hydroxyproline/radioactive hydroxyproline plus proline in neosynthesized collagen) was observed of about 50% in skin irradiated with UVA (xenon) but not in UVB-treated skin. Several of the above modifications (increased fibronectin biosynthesis, increased collagen type III to type I ratio) correspond to the modifications observed during the aging of non-irradiated hairless mice. Therefore it appears that UV irradiation accelerates the modifications of extracellular matrix biosynthesis observed during aging.     

Electric properties of non-irradiated and gamma-irradiated keratin

Dielectric measurements as a function of temperature and frequency are reported for non-irradiated and γ-irradiated keratin, the irradiation doses being 5 and 50 kGy. The effect of γ-irradiation on the dielectric permittivity of keratin is not observed up to 190°C. In this temperature range, the values of the relaxation time and dipole moment are similar for non-irradiated and irradiated keratin at the same temperature. The influence of irradiation is manifested as a shift of the parameter (_s−_∞) peaks associated with the process of denaturation, towards lower temperatures. This fact is supported by lower values of the dipole moment for irradiated than for non-irradiated keratin, as a result of a decrease in the number of polar groups in the side and main chains of the macromolecule in the irradiated samples.     

Removal of radionuclides from low level radioactive liquid waste by precipitation

Six elements in several organs of mice fed with Zn deficient diet (Zn-def. mice) and those fed with control diet (control mice) were analyzed by INAA. Zinc concentrations in the organs of Zn-def. mice were not distinctly lower than those of control mice except for bone and pancreas. However, Ce content increased significantly in all organs of Zn-def. mice compared with control mice, indicating the partial substitution of Co with Zn in metal proteins or other materials for the Zn-def. mice.     

Spectroscopic and electrical studies for the influence of ion beam and X-ray irradiation on poly-2-(N-propenamido-2-methylpropanesulfonic acid) and its polymer complex with cobalt chloride

The influence of argon ion beam and X-ray irradiations on poly-2-(N-propenamido-2-methylpropanesulfonic acid) (PPMPS) and its polymer complex with Co (II), (PPMPS-Co (II)), were studied using IR, UV/visible and d.c. electrical conductivity. After irradiation the polymer changed in color and become less soluble. The IR spectrum of irradiated PPMPS shows broadened bands at 3400 and 3550 cm^-1 which are assigned to stretch bands of NH and OH, respectively, as a consequence of intramolecular cyclization. Furthermore, a comparison of IR and UV/visible spectra of irradiated and non-irradiated PPMPS-Co(II), reveals that the main effect of irradiation was the degradation effect. Measurements of d.c. electrical conductivity for irradiated and non-irradiated polymers showed an increase of conductivity for the coordinated polymers compared to PPMPS. A relatively higher resistivity for the ion beam irradiated polymers and lower resistivity in case of X-ray irradiation have been observed. The increases of conductivity for the coordinated polymers compared to PPMPS were explained by the changes in glass transition temperatures (T_g) and activation energies for the different polymers.     

Protective effects of baicalin and quercetin on an iron-overloaded mouse: comparison of liver, kidney and heart tissues

Excessive accumulation of iron in the body can lead to organ injury. Some flavonoids which possess high affinity to iron can be used as iron chelators for curing iron overload diseases such as haemochromatosis. In this article, the effects of baicalin and quercetin on different mouse tissues (liver, kidney and heart) afflicted with iron overload-induced injury were studied. It was found that after administration of 500 mg kg?1 iron dextran for 45 days, the degree of oxidative injury in the three organs was different. When iron dextran-induced iron-overloaded mice were fed a diet containing baicalin or quercetin (1% w/w), both flavonoids showed significant effects in suppressing iron overload-induced injury. The efficiencies of both flavonoids on different tissues varied. Both flavonoids caused a significant decrease of iron content in liver and kidney tissues but not in the heart, whereas the flavonoids were more efficient in inhibiting the increase of carbonyl content and the thiobarbituric acid reactive substance levels in heart tissues. The results indicate that the protective effects of baicalin and quercetin on different tissues of iron-overloaded mice are different.     

Effect of γ-irradiation on volatile compounds of dried Welsh onion (Allium fistulosum L.)

The volatile compounds of γ-irradiated dried Welsh onion were isolated by simultaneous distillation–extraction (SDE) technique and then analyzed by gas chromatography–mass spectrometry (GC–MS) along with their non-irradiated counterparts. A total of 35 volatile compounds were identified in non-irradiated and 1 kGy irradiated samples and 36 volatile compounds were identified in 3, 5, 10 and 20 kGy irradiated samples so far belong to chemical classes of acid, alcohol, aldehyde, ester, furan, ketone and S-containing compound. S-containing compounds were detected as major volatile compounds of all experimental samples. Though the content of several compounds was increased after irradiation, content of major S-containing compounds was found to decreased in the process. Application of high-dose irradiation if required for microbial decontamination of dried Welsh onion is feasible as it enhanced the total concentration of volatile compounds by 31.60% and 24.85% at 10 and 20 kGy, respectively.