In vitro digestible energy of some agricultural residues,as influenced by gamma irradiation and sodium hydroxide

Experiments have been carried out to study the changes in the values of in vitro apparent organic matter digestibility (IVOMD) and in vitro digestible energy (IVDE) of wheat straw (WS), cotton seed shell (CSS), peanut shell (PS), soybean shell (SS), extracted olive cake (EOC) and extracted unpeeled sunflower seeds (ESS) after irradiation by various doses of gamma radiation (0, 100, 150, 200 kGy) or after spraying with different amounts of sodium hydroxide (NaOH): 0, 2, 4, and 6 g NaOH/25 ml water/100 g DM. The results indicate that there were significant increases in IVOMD and IVDE values for all irradiated samples and for sodium hydroxide treatments except for SS and ESS. Combined treatment of irradiation and sodium hydroxide resulted in a larger increase in the digestible energy than the individual treatments.     

Fractionation of high-dose electron beam irradiation of BPTB grafts provides significantly improved viscoelastic and structural properties compared to standard gamma irradiation

Purpose

Irradiation >30 kGy is required to achieve sterility against bacterial and viral pathogens in ACL allograft sterilization. However, doses >20 kGy substantially reduce the structural properties of soft-tissue grafts. Fractionation of irradiation doses is a standard procedure in oncology to reduce tissue damage but has not been applied in tissue graft sterilization.

Methods

Forty-four human 10-mm wide bone-patellar-tendon-bone grafts were randomized into four groups of sterilization with (1) 34 kGy of ebeam (2) 34 kGy gamma (3) 34 kGy fractionated ebeam, and (4) non sterilized controls. Graft´s biomechanical properties were evaluated at time zero. Biomechanical properties were analyzed during cyclic and load-to-failure testing.

Results

Fractionation of ebeam irradiation resulted in significantly higher failure loads (1,327 ± 305) than with one-time ebeam irradiation (1,024 ± 204; P = 0.008). Compared to gamma irradiation, significantly lower strain (2.9 ± 1.5 vs. 4.6 ± 2.0; P = 0.008) and smaller cyclic elongation response (0.3 ± 0.2 vs. 0.6 ± 0.4; P = 0.05), as well as higher failure loads (1,327 ± 305 vs. 827 ± 209; P = 0.001), were found. Compared to non-irradiated BPTB grafts, no significant differences were found for any of the biomechanical parameters. Non-irradiated controls had significantly lower cyclic elongation response and higher failure loads than ebeam and gamma irradiation.

Conclusions

In this study, it was found that fractionation of high-dose electron beam irradiation facilitated a significant improvement of viscoelastic and structural properties of BPTB grafts compared to ebeam and gamma irradiation alone, while maintaining levels of non-irradiated controls. Therefore, this technique might pose an important alternative to common methods for sterilization of soft-tissue allografts.     

Gamma-ray induced degradation of PCBs and pesticides using spent reactor fuel

Gamma-ray induced degradation of several chlorinated hydrocarbons was studied to identify candidate hazardous waste treatment processes. Spent nuclear fuel was used to irradiate PCBs and the pesticides DDT and lindane. Changes produced in these compounds due to ionizing radiation exposure are reported. The applied gamma doses varied from 10 to 100 kGy with an average energy of ca 700 keV. Following irradiation, the samples were analyzed by gas chromatography/mass spectrometry (GC/MS) to determine the extent of decomposition and the nature of the decomposition products. Doses of 100 kGy reduced PCBs to 15% of their initial concentration while DDT and lindane were reduced to below their GC/MS detection limits by doses of 50 kGy. The decomposition products detected were the next less chlorinated species resulting from a simple dechlorination reaction. Mass balance analysis shows however that the dechlorination reaction is not predominant at these gamma-ray doses. Dechlorination products account for only a small percentage of the original analyte concentrations at 100 kGy. The remaining analyte has apparently been decomposed to compounds not detectable by the GC/MS method used; that is, to volatile organics lighter than phenol.     

The effect of fast neutron and gamma irradiation on thermal,structural and colorant properties of 2,6-diaminopyridine

The variation in structural, thermal and colorant properties of 2,6-diaminopyridine were studied using differential scanning calorimetry (DSC), UV–visible, NMR spectroscopies and powder X-ray diffraction techniques, before and after fast neutrons irradiation with 2.12 and 3.50 kGy and gamma irradiation with 136.16 Gy doses. Under fast neutron irradiation, the sample enthalpy values, and melting and boiling temperatures were varied with increase in the irradiation dose. But the variation in boiling temperature was more pronounced than that of the melting point. However, there was no drastic change in these transition temperatures. The kinetic parameters were calculated using free isoconversional and Kissinger analysis methods. Moreover, UV–visible spectra showed that fast neutron and gamma irradiations had destroyed the color of the title compound. The gamma irradiation showed similar effect on structural and thermal properties. Results are also shown where the intensity of XRD patterns strongly depends on the irradiation dose. According to the NMR results, it seems that the collision occurs between para-hydrogen of 2,6-DAP and fast neutrons.     

Effect of Gamma Irradiation on the B Vitamins of Pork Chops and Chicken Breasts

Summary

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°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 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.     

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.     

Gamma irradiation of aloe-emodin induced structural modification and apoptosis through a ROS- and caspase-dependent mitochondrial pathway in stomach tumor cells

Purpose: The changes in molecular structure and the physiological properties of a gamma-irradiated aloe-emodin were examined.

Materials and methods: Aloe-emodin was gamma-irradiated at doses ranging from 0 to 150 kGy, and the molecular structure was then analyzed using high-performance liquid chromatography (HPLC). AGS cells were cultured in RPMI medium and treated gamma irradiated aloe-emodin. Cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptosis efficiency was investigated by cell cycle arrest, cell morphology, and signaling pathway. The structure of new radiolytic peak was identified by the hydrogen-nuclear magnetic resonance (¹H NMR).

Results: HPLC results showed that gamma irradiation induced new radiolytic peaks that were distinguishable from the aloe-emodin standard, and the area of new peaks was increased as the radiation dose increased. Gamma-irradiated aloe-emodin treatment significantly increased the cytotoxicity in AGS tumor cells. We also found that 150?kGy aloe-emodin increased the expression of Bax, cytosolic cytochrome c, PARP cleavage, and the activation of caspases-8, -9, -3, Bid, and Bcl-2. Treatment of 150?kGy aloe-emodin induced ROS production, DNA fragmentation, alterations of cell morphology, and the migration in AGS cells. Gamma-irradiated aloe-emodin induced an increase of sub-G1 phase and depolarization of mitochondrial membrane potential in AGS cells. We also confirmed that fractionated AEF1 (new radiolytic peak) induce the cell death, migration, an increase of sub-G1 phase and cytochrome c in a ROS-dependent manner.

Conclusions: The radiolysis product (AEF1) of aloe-emodin transformed by gamma-irradiation strongly induced apoptotic cell death in AGS cells, indicating AEF1 is a potential candidate drug for use in anti-cancer drug.     

High-level gamma dosimetry using phototransferred thermoluminescence in quartz

Phototransferred thermoluminescence (PTTL) in natural quartz, separated from sand, has been studied for its application in high-level gamma dosimetry. The paper reports dose-vs.-PTTL response of 110°C and 180°C peaks in the dose range of 10 Gy to 6 kGy. Using this method, the dose rate delivered to the sewage sludge during irradiation at SHRI facility, Vadodara, India, was estimated to be 0.35±0.02 kGy/h.     

Quality index of oils extracted from γ-irradiated peanuts (Arachis hypogaea L.) of the golden and bari varieties

Two varieties of peanuts were irradiated to 4, 6 and 8 kGy with Co⁶⁰. Their proximate compositions remained unaffected, but microbes were eliminated completely after irradiation to 8 kGy. HPLC was used to study tocopherols of irradiated and unirradiated oil samples. There were dose-dependent differences in physico-chemical values between the control and irradiated samples. Significant changes in tocopherol concentrations and peroxide values in the oils were observed after irradiation to 8 kGy. Fatty acid compositions did not change significantly. The study has shown that irradiation is an effective tool in preservation of peanut oil.     

Effect of γ-irradiation on gene expression of heat shock proteins in the foodborne pathogen Escherichia coli O157:H7

Abstract

Purpose: The expression levels of seven genes (clpB, dnaK, groES, grpE, htpG, htpX and ibpB) encoding heat shock proteins (HSP) in Escherichia coli O157:H7 (E. coli) gamma irradiated was investigated. Timing impact of post-irradiated RNA extraction on the expression levels of these seven genes was also studied at a dose damaging the bacterial cells (0.4 kGy).

Methods: Bacterial samples were γ-irradiated at 0.4 kGy and at a lethal dose of 1.3 kGy. RNA was extracted at 0 min post irradiation for both irradiation doses and at 15, 30, 60, 90 or 120 min post-irradiation at the dose damaging the cells. Quantification of the gene expression was performed using quantitative real-time polymerase chain reaction (q-RT-PCR).

Results: The expression of genes encoding HSP was a very dynamic process evolving rapidly when E. coli cells were irradiated at 0.4 kGy. Notably, groES, grpE and ibpB were more up- regulated at 1.3 kGy than those at 0.4 kGy.

Conclusions: For the seven genes studied there were more damaged proteins during irradiation at the lethal dose and this dose causes increased expression in HSP which contributes to damage reparation. Expression patterns of genes encoding HSP in E. coli treated by γ-irradiation are different from those treated by heat shock.     

Microdosimetric measurements in the thermal neutron irradiation facility of LENA reactor

A twin TEPC with electric-field guard tubes has been constructed to be used to characterize the BNCT field of the irradiation facility of LENA reactor. One of the two mini TEPC was doped with 50 ppm of ¹⁰B in order to simulate the BNC events occurring in BNCT. By properly processing the two microdosimetric spectra, the gamma, neutron and BNC spectral components can be derived with good precision (~6%). However, direct measurements of ¹⁰B in some doped plastic samples, which were used for constructing the cathode walls, point out the scarce accuracy of the nominal ¹⁰B concentration value. The influence of the Boral^® door, which closes the irradiation channel, has been measured. The gamma dose increases significantly (+51%) when the Boral^® door is closed. The crypt-cell-regeneration weighting function has been used to measure the quality, namely the RBE_µ value, of the radiation field in different conditions. The measured RBE_µ values are only partially consistent with the RBE values of other BNCT facilities.     

Sterilization of bone allografts by microwave and gamma radiation

Abstract

Purpose: Bone allografts are used to enhance healing in osteotomies, arthrodesis, fractures and to replace bone loss resulting from tumour or trauma. However, a major concern associated with the bone allografts is the potential for disease transmission. Various sterilization techniques have been developed to prevent infection through allografts. This study was undertaken with the aim of exploring the use of microwave radiation for sterilization of bone allografts and to compare with gamma radiation sterilization.

Materials and methods: Bone allografts were processed from femoral heads obtained from living donors. The effect of microwave and gamma radiation on the bacteria isolated from bone allograft was evaluated. The microwave radiation treatment was performed at 2450 MHz (frequency) for varying lengths of time at maximum power 900 Watts (W). Viability of three Gram-positive bacteria – Bacillus subtilis, Corynebacterium, Staphylococcus aureus and three Gram-negative bacteria – Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa was examined after irradiation of bacterial suspensions and contaminated processed bone allografts. The sterility test of microwave and gamma irradiated bone allograft was carried out in accordance with ISO (International Organization for Standardization) 11737-2.

Results: Microwave irradiation (2450 MHz and 900 W) of bacterial isolates resulted in complete inactivation within 60 seconds. The contaminated bone samples showed no growth of organisms after 2 minutes of exposure to microwave irradiation. No viable counts were detected in bone grafts inoculated with Gram-negative bacterial species on gamma irradiation to a dose of 15 kGy. Bones contaminated with Gram-positive bacteria required a higher dose of 20 kGy for complete inactivation.

Conclusions: The study shows that sterilization of contaminated femoral head bone allografts can be achieved by short exposure of 2 min to 2450 MHz and 900 W microwave radiation.     

In search of an ecological dosimeter for high dose measurements: Aqueous sucrose solutions

The purpose of this work was to study physico-chemical changes in irradiating aqueous sucrose solutions from the point of view of their usefulness for technological dosimetry. Non-irradiated sucrose solutions are optically “empty” in the visible and near UV range. After gamma irradiation an absorption band with a maximum at 263 nm appears. It was confirmed that this band can be used as dosimetric signal for the dose range: 1–10 kGy. The species responsible for the 263 nm band is a neutral product of sucrose oxidation by an OH radical. High energy electron irradiation creates another UV absorbing species with the absorption band peaked at 270 nm. Further investigations are necessary to establish to what extent it can be used for electron beam dosimetry.     

Sterilization of bone allografts by microwave and gamma radiation

Abstract Purpose: Bone allografts are used to enhance healing in osteotomies, arthrodesis, fractures and to replace bone loss resulting from tumour or trauma. However, a major concern associated with the bone allografts is the potential for disease transmission. Various sterilization techniques have been developed to prevent infection through allografts. This study was undertaken with the aim of exploring the use of microwave radiation for sterilization of bone allografts and to compare with gamma radiation sterilization. Materials and methods: Bone allografts were processed from femoral heads obtained from living donors. The effect of microwave and gamma radiation on the bacteria isolated from bone allograft was evaluated. The microwave radiation treatment was performed at 2450 MHz (frequency) for varying lengths of time at maximum power 900 Watts (W). Viability of three Gram-positive bacteria - Bacillus subtilis, Corynebacterium, Staphylococcus aureus and three Gram-negative bacteria - Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa was examined after irradiation of bacterial suspensions and contaminated processed bone allografts. The sterility test of microwave and gamma irradiated bone allograft was carried out in accordance with ISO (International Organization for Standardization) 11737-2. Results: Microwave irradiation (2450 MHz and 900 W) of bacterial isolates resulted in complete inactivation within 60 seconds. The contaminated bone samples showed no growth of organisms after 2 minutes of exposure to microwave irradiation. No viable counts were detected in bone grafts inoculated with Gram-negative bacterial species on gamma irradiation to a dose of 15 kGy. Bones contaminated with Gram-positive bacteria required a higher dose of 20 kGy for complete inactivation. Conclusions: The study shows that sterilization of contaminated femoral head bone allografts can be achieved by short exposure of 2 min to 2450 MHz and 900 W microwave radiation.     

Responses of GafChromic films for distribution of extremely high doses from synchrotron radiation.

Using 10 and 30 keV photons from synchrotron radiation, we measured optical density curves of GafChromic films MD-55 and HD-810 and compared the results with those of (60)Co gamma rays up to 500 kGy. The scanners used were a fluorescence digitizer and a color film scanner. In addition, the energy responses were measured between 10 and 100 keV. The values were 0.8 for HD-810 above 10 keV and 0.95 at 100 keV for MD-55, which decreased to 0.6 at 30 keV.     

The effects of chronic gamma irradiation on oxidative stress response and the expression of anthocyanin biosynthesis-related genes in wheat (Triticum aestivum)

Abstract

Purpose: To investigate the mechanisms of adaptation and tolerance to ionizing radiation using chronic radiation in wheat.

Materials and methods: We exposed wheat plants to chronic gamma irradiation (50 Gy) for 2, 4, and 6 weeks and measured various biological parameters.

Results: Plant height was reduced by exposure to gamma irradiation; this effect increased with increasing exposure time. Photosynthetic pigment levels decreased with increasing exposure time, while anthocyanin levels significantly increased after exposure to gamma rays. The activities of antioxidant enzymes (superoxide dismutase [SOD], ascorbate peroxidase [APX], catalase [CAT], and peroxidase [POD]) and malondialdehyde (MDA) levels increased with increasing duration of exposure to gamma irradiation. Electron spin resonance (ESR) signals were strongly detected in wheat that was gamma-irradiated for two weeks and then gradually decreased with increasing exposure time. The expression of anthocyanin biosynthesis genes (flavanone 3-hydroxylase [F3H], dihydroflavonol reductase [DFR], anthocyanin reductase [ANS], and UDPG-flavonoid glucosyl transferase [UFGT]) and sugar contents increased after exposure to gamma rays.

Conclusions: This suggests that exposure to ionizing radiation according to increase of exposure time has led to efficient induction of anthocyanin and antioxidant enzyme activities. This study indicates that reactive oxygen species (ROS) is eliminated by biosynthesis of anthocyanin and antioxidant enzymes. This study helps elucidate the biological effects of various durations of low-dose exposure to chronic gamma radiation in wheat plants.     

Ultrafast nuclear myocardial perfusion imaging on a new gamma camera with semiconductor detector technique: first clinical validation

Purpose

To assess the diagnostic performance of a novel ultrafast cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors for nuclear myocardial perfusion imaging (MPI).

Methods

The study group comprised 75 consecutive patients (55 men, BMI range 19–45 kg/m²) who underwent a 1-day ^99mTc-tetrofosmin adenosine-stress/rest imaging protocol. Scanning was performed first on a conventional dual-detector SPECT gamma camera (Ventri, GE Healthcare) with a 15-min acquisition time each for stress and rest. All scans were immediately repeated on an ultrafast CZT camera (Discovery 530 NMc, GE Healthcare) with a 3-min scan time for stress and a 2-min scan time for rest. Clinical agreement (normal, ischaemia, scar) between CZT and SPECT was assessed for each patient and for each coronary territory using SPECT MPI as the reference standard. Segmental myocardial tracer uptake values (percent of maximum) using a 20-segment model and left ventricular ejection fraction (EF) values obtained using CZT were compared with those obtained using conventional SPECT by intraclass correlation and by calculating Bland-Altman limits of agreement.

Results

There was excellent clinical agreement between CZT and conventional SPECT on a per-patient basis (96.0%) and on a per-vessel territory basis (96.4%) as shown by a highly significant correlation between segmental tracer uptake values (r=0.901, p<0.001). Similarly, EF values for both scanners were highly correlated (r=0.976, p<0.001) with narrow Bland-Altman limits of agreement (?5.5–10.6%).

Conclusion

The novel CZT camera allows a more than fivefold reduction in scan time and provides clinical information equivalent to conventional standard SPECT MPI.     

The effect of meal energy content on gastric emptying

Gastric emptying (GE) has been reported to be influenced by meal weight (grams) and composition (% carbohydrate:protein:fat) but the effect of meal energy content (kcal) on gastric emptying, independent of composition, has not been thoroughly investigated by scintigraphic techniques. In order to determine the effect of caloric content on GE, 12 normal male volunteers, ranging in age from 19-28 yr (mean = 24 yr), had GE scans (n = 32) performed with a solid meal of fixed composition (carbohydrate 40%:protein 40%:fat 20%) but varying energy content [150 kcal (n = 9), 300 kcal (n = 14), and 600 kcal (n = 9)]. Increasing the energy content of the meal of fixed composition progressively delayed gastric emptying: T1/2 = 57', 70', and 95' for 150 kcal, 300 kcal and 600 kcal, respectively (p less than 0.05; Student's t-test). Reproducibility, evaluated by performing GE scans (n = 8) on different days in the same individual (n = 4) with the same meal (300 kcal), was good (r greater than or equal to 0.89). Variability varied inversely with meal energy content (CV:150 kcal greater than or equal to 300 kcal and 600 kcal). The 300 kcal mean seems to be the best compromise since it results in less intersubject variability than 150 kcal, has minimal intrasubject variability, but is not as prohibitively large as the 600 kcal meal.     

Application of jade samples for high-dose dosimetry using the EPR technique

The dosimeter characteristics of jade samples were studied for application in high-dose dosimetry. Jade is the common denomination of two silicates: jadeite and actinolite. The EPR spectra of different jade samples were obtained after irradiation with absorbed doses of 100 Gy up to 20 kGy. The jade samples present signals that increase with the absorbed dose (g-factors around 2.00); they can be attributed to electron centers. The EPR spectra obtained for the USA jade samples and their main dosimetric properties as reproducibility, calibration curves and energy dependence were investigated.