kGy Gamma Irradiation Research Articles

The effect of free-living nematodes on nitrogen mineralisation in undisturbed and disturbed soil cores

Soil fauna, particularly nematodes, are considered to strongly contribute to nitrogen mineralisation through grazing on microflora during decomposition. Demonstration of this effect has mostly relied on calculation-based soil food web analyses or experiments involving simplified and artificially constructed food webs. We carried out an incubation experiment in which defaunated soil cores were reinoculated with entire soil nematode populations extracted from bulk soil and during which nitrogen mineralisation was measured. Both undisturbed and disturbed cores were prepared to investigate whether a representative pore structure influences the effect of entire free-living nematode populations on nitrogen mineralisation. Cores were subjected to a 5 kGy gamma irradiation dose sufficient to eliminate all soil fauna while leaving the microbial biomass largely intact. Half of the irradiated cores were reinoculated with nematodes extracted from a corresponding volume of bulk soil and incubated for 82 days. The microbial biomass was not strongly affected by gamma irradiation or nematode addition but declined strongly in all treatments during incubation. Reinoculation of nematodes was successful in establishing populations of a similar size and composition as in the control samples. Net nitrogen mineralisation from indigenous soil organic matter was observed in all treatments throughout the incubation, but was always more pronounced in irradiated cores. Total mineral nitrogen concentrations did not differ significantly between simply irradiated and irradiated then reinoculated cores. However by the end of the incubation period nematode addition resulted in 87% and 23% more NO3−–N g−1 dry soil in undisturbed and disturbed cores respectively, while NH4+–N g−1 dry soil decreased by 50% in both core types. We found no convincing evidence for a contribution of free-living nematodes on total nitrogen mineralisation, but the activity of nitrifying organisms was clearly stimulated by nematode grazing.

Major soluble proteome changes in Deinococcus deserti over the earliest stages following gamma-ray irradiation

BackgroundDeinococcus deserti VCD115 has been isolated from Sahara surface sand. This radiotolerant bacterium represents an experimental model of choice to understand adaptation to harsh conditions encountered in hot arid deserts. We analysed the soluble proteome dynamics in this environmentally relevant model after exposure to 3 kGy gamma radiation, a non-lethal dose that generates massive DNA damages. For this, cells were harvested at different time lapses after irradiation and their soluble proteome contents have been analysed by 2-DE and mass spectrometry.ResultsIn the first stage of the time course we observed accumulation of DNA damage response protein DdrB (that shows the highest fold change ~11), SSB, and two different RecA proteins (RecAP and RecAC). Induction of DNA repair protein PprA, DNA damage response protein DdrD and the two gyrase subunits (GyrA and GyrB) was also detected. A response regulator of the SarP family, a type II site-specific deoxyribonuclease and a putative N-acetyltransferase are three new proteins found to be induced. In a more delayed stage, we observed accumulation of several proteins related to central metabolism and protein turn-over, as well as helicase UvrD and novel forms of both gyrase subunits differing in terms of isoelectric point and molecular weight.ConclusionsPost-translational modifications of GyrA (N-terminal methionine removal and acetylation) have been evidenced and their significance discussed. We found that the Deide_02842 restriction enzyme, which is specifically found in D. deserti, is a new potential member of the radiation/desiccation response regulon, highlighting the specificities of D. deserti compared to the D. radiodurans model.

Radiation Response of Bacteria Associated with Human Cancellous Bone

Cancellous bones from twenty five live tissue donors were tested for bacterial contamination and initial bioburden ranged from 4.1×10 1 to 3.1×10 3 cfu/g (average 9.0×10 2 cfu/g). Forty six representative bacterial isolates were characterized on the basis of morphological, cultural and biochemical characteristics. Staphylococcus spp. was found to be predominant contaminant in tissue samples (41.30%). To assess the radiation resistance all the bacterial isolates were exposed to 1 to 10 kGy gamma radiation from 60 Co gamma source. The radiation decimal reduction dose values (D10) and twelve log reduction values (12 D value) of the isolates were calculated. D10 values of the isolates were ranged from 0.59 to 1.20 kGy. Among the studied bacterial isolates, Streptococcus spp. was the most radioresistant isolates (D10 value 0.93-1.20 kGy) and three of the Streptococcus spp. survived up to 8 kGy. All the bacterial isolates were killed at 9 kGy. Twelve log reduction value (12D value) of the most resistant isolate was 14.4 kGy. These results indicate that standard radiation sterilization dose (25 kGy) is satisfactory for the sterilization of the cancellous bone allografts. Keywords- Bioburden, Cancellous bone, Radiation resistance, Staphylococcus, Streptococcus, Sterilization

Development of a Qualitative Dose Indicator for Gamma Radiation Using Lyophilized Deinococcus

The feasibility of using Deinococcus showing strong resistance to both desiccation and ionizing radiation as a dose indicator of gamma radiation exposure was evaluated. Three Deinococcus strains having different levels of radiation resistance, Deinococcus radiodurans (DRD), Deinococcus radiopugnans (DRP), and the DRD pprI mutant (DRM), were selected to develop an appropriate dose indicator for a broad range of exposures. DRD, DRP, and DRM cultures with different numbers of cells [~10(7) to 10(3) colony forming units (CFU)/100 microliter] were lyophilized and subjected to various doses of gamma radiation to determine a critical dose that inhibited bacterial growth completely. Finally, a combination of DRD at ~10(7) and ~10(6) CFU, DRP at ~10(5) CFU, and DRM at ~10(4) CFU successfully indicated exposure to 5, 10, 20, and 30 kGy of gamma radiation, respectively. This study shows the possibility of developing a qualitative indicator of radiation exposure using Deinococcus.

Paper 260: Electronic Beam Sterilization of Soft-tissue Grafts Maintains Significantly Improved Biomechanical Properties at High-dose Irradiation (34 kGy) than Standard Gamma Treatment

Gamma irradiation is the most frequently used sterilization procedure for soft-tissue allografts as they are used in ACL surgery. However, biomechanical properties of gamma irradiated allografts at dosages > 20 kGy are significantly reduced. Electronic beam (Ebeam) irradiation dose and other parameters can be more accurately controlled than it is economically feasible than with gamma irradiation. Also, it has been shown that the addition of CO2 with E-beam sterilization at low temperatures allows for a significant reduction of free radicals build-up which is mainly responsible for the loss of tissue strength. It was the objective of this study to compare the impact of 34 kGy gamma vs. E-beam irradiation on the biomechanical properties of human bone-patellar tendon-bone grafts at the time of sterilization. Paired 10 mm-wide human bone-patellar tendon-bone (BPTB) grafts were harvested from 10 donors and split into two groups (each n=10): A) Ebeam, B) Gamma. All grafts were irradiated with 34 kGy. 10 non-irradiated BPTB grafts of identical dimensions were used as controls. All grafts underwent biomechanical testing: preconditioning (10 cycles, 0 – 20 N); cyclic loading (200 cycles, 20 - 200 N) and a load-to-failure (LTF) test. The strain rate was 150 mm min-1. Graft motion during cyclic loading was tracked with an optical measurement system. Failure load and displacement at failure were recorded and stiffness was derived from these values. The strain difference between the first and last cycles as well as creep were used as a determinant of viscoelasticity. Student t-test was used for statistical comparison of both study groups (paired) and controls (independent). Level of significance was set at p < 0.05. Stiffness of non-irradiated controls (199.6 ± 59.1 N/mm) and ebeam sterilized grafts (192.8 ± 58.0 N/mm) did not significantly differ, while gamma-irradiated grafts had significantly lower stiffness (170.6 ± 58.2 N/mm) than controls (p<0.05). Failure loads were significantly lower in both study groups (ebeam: 1139 ± 445 N, gamma: 1073 ± 617 N) than in the controls (1741 ± 304 N) (p<0.05). Creep was significantly larger in the gamma irradiated (1,06 ± 0,58 mm) than in the ebeam (0,26 ± 0,24 mm) and control (0,20 ± 0,17 mm) group that did not differ significantly. Strain difference was not different between either control or study groups. This study shows that the impairment of biomechanical properties of soft-tissue allografts at high irradiation doses of 34 kGy is substantially reduced with the ebeam procedure compared to standard gamma treatment. Considering the results of this study and the improved control of irradiation application with electronic beam, this technique might be a promising alternative in soft-tissue sterilization. However, a significant reduction of failure strength has to be conceded with electronic beam irradiation, too. Therefore, in future studies it is important to gain better understanding of the underlying processes that affect soft-tissue strength and to eventually eliminate these adverse effects.

Sterilization of tendon allografts: a method to improve strength and stability after exposure to 50 kGy gamma radiation

Terminal sterilization of tendon allografts with high dose gamma irradiation has deleterious effects on tendon mechanical properties and stability after implantation. Our goal is to minimize these effects with radio protective methods. We previously showed that radio protection via combined crosslinking and free radical scavenging maintained initial mechanical properties of tendon allografts after irradiation at 50 kGy. This study further evaluates the tissue response and simulated mechanical degradation of tendons processed with radio protective treatment, which involves crosslinking in 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide followed by soaking in an ascorbate/riboflavin-5-phosphate solution. Control untreated and treated tendons were irradiated at 50 kGy and implanted in New Zealand White rabbit knees within the joint capsule for four and 8 weeks. Tendons were also exposed to cyclic loading to 20 N at one cycle per 12 s in a collagenase solution for 150 cycles, followed by tension to failure. Control irradiated tendons displayed increased degradation in vivo, and failed prematurely during cyclic processing at an average of 25 cycles. In contrast, radio protected irradiated tendons displayed greater stability following implantation over 8 weeks, and possessed strength at 59 % of native tendons and modulus equivalent to that of native tendons after cyclic loading in collagenase. These results suggest that radio protective treatment improves the strength and the stability of tendon allografts.

The synergistic effects of combined NaOCl, gamma irradiation and vitamin B1 on populations of Aeromonas hydrophila in squid

The present study investigated the synergistic disinfection effects of combined NaOCl/gamma irradiation and NaOCl/vitamin B1 treatment against Aeromonas hydrophila ATCC 7966 in tryptic soy broth (TSB) and squid. The synergistic effects were not dependent on the concentration of NaOCl or the dose of gamma irradiation, but were dependent on the vitamin B1 concentration. Synergistic values for NaOCl/gamma irradiation treatment in TSB and squid were −0.37 to 2.09 log10 CFU/mL and 0.00–2.92 log10 CFU/g, respectively. The largest synergistic values, 2.09 log10 CFU/mL in TSB and 2.92 log10 CFU/g in squid, were as a result of treatment with a combination of 40 ppm NaOCl and 1.0 kGy gamma irradiation and 80 ppm NaOCl and 2.0 kGy gamma irradiation, respectively. Synergistic values for NaOCl/vitamin B1 treatment in TSB and squid were 0.59–2.98 log10 CFU/mL and 0.06–1.35 log10 CFU/g, respectively. The largest synergistic values, 2.98 log10 CFU/mL in TSB and 1.35 log10 CFU/g in squid, were as a result of treatment with a combination of 300 ppm NaOCl and 1000 ppm vitamin B1 and 1000 ppm NaOCl and 1000 ppm vitamin B1, respectively. The results in the broth study suggest that the combination of 40 ppm NaOCl and 1.0 kGy gamma irradiation and 300 ppm NaOCl and 1000 ppm vitamin B1 could be regarded as a potential optimum hurdle approach for application to real target foods and(or) food surfaces for the control of A. hydrophila. Moreover, the results in the food study indicate that the combination treatment of 80 ppm NaOCl and 2.0 kGy gamma irradiation and 100 ppm NaOCl and 1000 ppm vitamin B1 could possibly be used in seafood production, processing, and distribution processes to enhance seafood safety.

UV–visible, infrared absorption spectra of undoped and TiO2-doped lead phosphate glasses and the effect of gamma irradiation

Undoped and TiO2-doped lead phosphate glasses were prepared. Ultraviolet (UV)–visible and Fourier transform-infrared (IR) absorption spectra of the prepared samples were measured before and after being subjected to doses of 30 and 60 kGy of gamma irradiation. The parent undoped lead phosphate glass reveals charge transfer UV absorption bands which are attributed to the presence of unavoidable iron impurities contaminated within the raw materials used for the preparation of the glasses and the sharing of divalent lead (Pb2+) ions. Experimental spectral data indicate that the doped titanium ions are involved in such glasses in two valences, namely the trivalent and tetravalent states. The predominant trivalent titanium (Ti3+) ions are characterized by its purple color and exhibiting two visible absorption bands at about 500–550 and 700–720 nm. The lesser tetravalent titanium (Ti4+) ions belong to the d0 configuration and generally exhibit only an UV absorption band. Spectral data show that gamma irradiation causes noticeable changes in the undoped and TiO2-doped samples in the UV range while the effects are limited in the visible range. The observed changes in the UV region are attributed to photochemical reactions while TiO2-doped samples show retardation or shielding toward continuous gamma irradiation together with the sharing of heavy Pb2+ ions. IR absorption spectra reveal the vibrations of several phosphate groups including the metaphosphate chains as the main structural building units together with the possible Pb‒O vibrations.

Preparation of dissolvable albumin stents for vascular anastomosis with a 1.9 µm laser and in vitro mechanical strength assessments

We present a clinically relevant method for producing and sterilizing dissolvable albumin stents to provide intraluminal support during vascular anastomosis, and a method for photothermally soldering vessels using a 1.9 µm diode laser with a 200-µm spot size, albumin solder, and water as the chromophore. Our aim in this study was to assess the mechanical integrity of soldered vessels, and to determine if gamma-irradiation affected the solubility of the stents. The axial tensile strength and burst pressure of 3.75 ± 0.3 mm inner-diameter vessels soldered with varied swath width (1-7 mm), laser power (430-610 mW), solder concentration (22-46%w/w), and solder layering (1-3 layers) was tested in vitro. Stent dissolution was monitored by weight in blood, and with UV absorbance measurements in phosphate buffered saline (PBS). Solubility was measured for stents sterilized by 25 kGy gamma-irradiation, and stents with varied diameter and wall thickness. Optimized soldering parameters yielded tensile strengths of 4.4 ± 1.2 N and burst pressures of 400 ± 90 mm Hg with stay sutures. Differences in stent solubility in blood and PBS were not statistically significant (p = 0.99). Sterilization by 25 kGy gamma-irradiation did not cause significant changes (p > 0.6) in stent solubility, which was primarily volume-dependent. Under simulated intravascular flow conditions, 3 mm stents dissolved completely with 2.7 ± 0.7 ml/mg. The results show that fast-dissolving stents can be produced reliably using the extrusion technique, and sterilized by gamma-irradiation. Without stay sutures, soldered vessels exhibited low tensile strength, but burst pressures comparable to sutured vessels. It was concluded that stay sutures would be necessary in vivo due to degradation of the tensile strength of soldered vessels with exposure to moisture.

BROWNING OF LITCHI FRUIT PERICARP: ROLE OF POLYPHENOL OXIDASE, PEROXIDASE, PHENYLALANINE AMMONIA LYASE AND EFFECT OF GAMMA RADIATION*

ABSTRACT A dose of 0.5 kGy of gamma radiation in combination with low temperature storage (4C) helped in extending the shelf life of two Indian litchi (Litchi chinensis) cultivars (“Shahi” and “China”) up to 28 days. However, during storage, pericarp browning in litchi was observed. Hence, in the current study to understand the mechanism of pericarp browning, total phenolics and the activities of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia lyase (PAL) were evaluated. The PPO activity and phenolics were found to be higher in “China” than in “Shahi,” whereas POD and PAL activities were higher in “Shahi.” PPO and phenolics played a major role in the pericarp browning. Radiation treatment increased the PAL activity and hence the level of total phenolics, whereas PPO and POD activities were inhibited. This may explain reduction in browning in irradiated fruits compared with nonirradiated fruits. PRACTICAL APPLICATIONS Browning of litchi pericarp affects the appeal of the fruit and is one of the main problems encountered by the cultivators and traders, leading to significant economic losses. Understanding the role of different enzymes and level of phenolics in the process of browning will help find suitable postharvest methods for the control of browning. As the radiation treatment is being used as a mandatory quarantine treatment in many countries for export, further understanding the effect of radiation treatment on the browning and related enzyme activities will help in postharvest management and improving international trade of litchi.

Effect of gamma irradiation on microbial load, physicochemical and sensory characteristics of soybeans (Glycine max L. Merrill)

Gamma irradiation is highly effective in inactivating microorganisms in various foods and offers a safe alternative method of food decontamination. In the present study, soybeans (Glycine max L. Merrill) were treated with 0, 1.0, 3.0, 5.0 and 10.0KGy of gamma irradiation. Microbial populations on soybeans, isoflavone, tocopherol contents, raffinose family oligosaccharides, color and sensory properties were evaluated as a function of irradiation dose. The results indicated that gamma irradiation reduced aerobic bacterial and fungal load. Irradiation at the doses applied did not cause any significant change (p>0.05) in the contents of isoflavone of soybeans, but decreased tocopherol contents. The content of key flatulence-producing raffinose family oligosaccharides in irradiated soybeans (10.0kGy) decreased by 82.1% compared to the control. Sensory analysis showed that the odor of the soybeans was organoleptically acceptable at doses up to 5.0kGy and no significant differences were observed between irradiated and nonirradiated samples in flavor, texture and color after irradiation.

Evaluation of nutritional substrate and physical stress (gamma irradiation) in -glucan productivity by mushroom (Pleurotus ostreatus)

-1 ) and gamma irradiation. On application of physical stress factors (gamma irradiation, 1 to 6 kGy), 1 kGy gamma irradiation doses resulted in an increase in: protein (37.5%), carbohydrates (32.15%), glucans (12.0%) and growth (dry mass, 14.8%); these were due to the enhancement of low doses (1.0 kGy) of gamma irradiation upon growth and metabolism that was synergized by the radioprotective components (cysteine) that prevailed in the animal extract. This substrate supported the growth and glucan production of Pleurotus ostreatus than by Schizophyllum commune and Saccharomyces cerevisae. There are suggested procedures to assure the percentage of glucan purity and entity. The APCEB substrate is a general basic formula in which the animal and plant remains can be replaced by many others. The yield of this media economizes the glucan production.

Age- and time interval-specific gamma radiation-induced DNA damage in adult maize weevils, Sitophilus zeamais Motschulsky, assessed using comet assays

The gamma radiation-induced DNA damage in adult maize weevils, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), was assessed using single-cell electrophoresis (comet assay). Analysis of DNA damage following 0.5 and 1.0 kGy of gamma radiation was performed using cells from 1- and 15-day-old adults. Gamma-irradiated adults from both age groups showed typical DNA fragmentation, whereas cells from non-irradiated adults showed more intact DNA than young S. zeamais. Investigations using the comet assay showed that tail length, % tail DNA and % DNA damage all increased in adults of both age groups when compared to the control insects. A maximum comet length of 227.33 μm was recorded for 15-day-old adults at 24 h after irradiation with 1.0 kGy and a minimum of 50.12 μm for 1-day-old adults at 0 h after irradiation with 0.5 kGy. The percentage of DNA damage increased up to 57.31% and 68.15% for 1- and 15-day-old adults, respectively, at 24 h after irradiation with 1.0 kGy, whereas only 8.58% and 12.22% DNA damage were observed in the control batches. The results also showed that percentage of DNA damage increased at 24 h after irradiation compared to that at 0 h. However, further studies are needed to confirm these results.

Spectroscopic evaluation of painted layer structural changes induced by gamma radiation in experimental models

The degradation of cultural heritage objects by insects and microorganisms is an important issue for conservators, art specialists and humankind in general. Gamma irradiation is an efficient method of polychrome wooden artifacts disinfestation. Color changes and other modifications in the physical chemical properties of materials induced by gamma irradiation are feared by cultural heritage responsible committees and they have to be evaluated objectively and precisely. In this paper FTIR and FT-Raman spectroscopy methods were used to investigate the structural changes in some experimental models of tempera paint layers on wood following 11 kGy gamma irradiation at two dose rates. Radiation chemistry depends on the particular pigment, matrix formed by protein, resin (in case of varnished samples) and water presence. For the majority of painted layer in experimental models very small spectral variations were observed. Small changes in the FTIR spectra were observed for the raw sienna experimental model: for the higher dose rate the egg yolk protein oxidation peaks and the CH stretching bands due to lipids degradation products increased.

Modulation of the Pharmacological and Biochemical Actions of Leiurus quinquestriatus (L.q) Scorpion Venom by Exposure to Gamma Radiation

Back ground This study was undertaken to evaluate the effect of gamma radiation (1.5 KGy & 3 KGy) on L.q scorpion venom. This was carried out by studying the toxicological, biochemical & immunological properties of the venom before and after exposure to gamma radiation. Material and methods Animals, venom, antivenin, gamma radiation, 125I. Results Data revealed that the toxicity of irradiated venom (1.5 KGy & 3 KGy) decreased as compared to that of the native one. LD50 of irradiated venom were 3.5 mg/kg & 7.5 mg/kg respectively while, that of the native venom was (0.39 mg/kg). Moreover, the distribution of 125I-labeled L.q venom was studied in male Swiss mice tissue using chloramine-T method by being injected intravenously. At various time intervals, urine and blood were collected and the animals were sacrificed. Brain, lungs, heart, liver, kidneys, spleen, intestine, bone and muscle were isolated in order to determine the radioactivity content. The highest contents of 125I-labeled L.q venom were found in the liver and kidney that were quickly excreted into the urinary tract. Trial to label irradiated (1.5 & 3 KGy) L.q venom was unsuccessful due to its decomposition. For that reason the utilization of the labeled irradiated L.q venom is of no meaning. In immunodiffusion technique, both irradiated and native venoms exhibited prominent precipitin bands indicating high concentration of specific antibodies against polyvalent antivenin with venom. Furthermore, the effect of half the LD50 of native or irradiated (1.5 KGy) L.q venom was studied on the activities of certain enzymes: ASAT, ALAT, LDH, CPK, CPK-MB, and the levels of total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol and the oxidative stress biomarkers (plasma MDA & blood GSH). Biochemical measurements showed that scorpion venom envenomation caused significant (p < 0.05) elevation in serum ASAT, ALAT, LDH, CPK as well as CPK-MB activities, blood GSH level while, caused significant (p < 0.05) reduction in triglyceride, HDL-cholesterol. In contrast, the 1.5 KGy gamma irradiated L.q venom showed no alterations except in HDL-cholesterol that significantly decreased compared to that of the non-envenomated normal rats. Conclusion These results indicated that 1.5 KGy gamma irradiation of venom offer an effective method for reducing the toxic effect of venom.

Modulation of the Pharmacological and Biochemical Actions of Leiurus quinquestriatus (L.q) Scorpion Venom by Exposure to Gamma Radiation

Back ground This study was undertaken to evaluate the effect of gamma radiation (1.5 KGy & 3 KGy) on L.q scorpion venom. This was carried out by studying the toxicological, biochemical & immunological properties of the venom before and after exposure to gamma radiation. Material and methods Animals, venom, antivenin, gamma radiation, 125I. Results Data revealed that the toxicity of irradiated venom (1.5 KGy & 3 KGy) decreased as compared to that of the native one. LD50 of irradiated venom were 3.5 mg/kg & 7.5 mg/kg respectively while, that of the native venom was (0.39 mg/kg). Moreover, the distribution of 125I-labeled L.q venom was studied in male Swiss mice tissue using chloramine-T method by being injected intravenously. At various time intervals, urine and blood were collected and the animals were sacrificed. Brain, lungs, heart, liver, kidneys, spleen, intestine, bone and muscle were isolated in order to determine the radioactivity content. The highest contents of 125I-labeled L.q venom were found in the liver and kidney that were quickly excreted into the urinary tract. Trial to label irradiated (1.5 & 3 KGy) L.q venom was unsuccessful due to its decomposition. For that reason the utilization of the labeled irradiated L.q venom is of no meaning. In immunodiffusion technique, both irradiated and native venoms exhibited prominent precipitin bands indicating high concentration of specific antibodies against polyvalent antivenin with venom. Furthermore, the effect of half the LD50 of native or irradiated (1.5 KGy) L.q venom was studied on the activities of certain enzymes: ASAT, ALAT, LDH, CPK, CPK-MB, and the levels of total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol and the oxidative stress biomarkers (plasma MDA & blood GSH). Biochemical measurements showed that scorpion venom envenomation caused significant (p < 0.05) elevation in serum ASAT, ALAT, LDH, CPK as well as CPK-MB activities, blood GSH level while, caused significant (p < 0.05) reduction in triglyceride, HDL-cholesterol. In contrast, the 1.5 KGy gamma irradiated L.q venom showed no alterations except in HDL-cholesterol that significantly decreased compared to that of the non-envenomated normal rats. Conclusion These results indicated that 1.5 KGy gamma irradiation of venom offer an effective method for reducing the toxic effect of venom.

Gamma radiolysis of ceftriaxone sodium for water treatment: assessments of the activity

As large quantities of antibiotics have been misused in human and veterinary medicine, many different classes of antibiotics with low concentration have been detected in the environmental water. This existence may cause severe ecosystem alterations. Ceftriaxone sodium was employed as the targeted antibiotic to evaluate gamma radiolysis of antibiotics based on the primary elimination test and activity assay. The decomposition percentage of ceftriaxone sodium (20 microg/ml) in purified water increases with increasing doses and reaches 98% under 5 kGy of gamma radiation. The residual activity after gamma radiation does not follow the corresponding decomposition percentage of ceftriaxone sodium. Liquid chromatography and mass spectrometry (LC-MS) was subsequently employed to analyze possible structures of radiolytic products relating to the activity. Different degrees of the residual activity may attribute to different cleavage pathways of ceftriaxone sodium produced by radiation with different doses. The results indicate that the radiolytic treatment is a highly-effective means for degradation of ceftriaxone sodium, and the activity status of ceftriaxone sodium after primary elimination should be taken into consideration for selecting a degrading dose. Three kGy is the appropriate dose for radiolysis of ceftriaxone sodium in purified water.

Effect of gamma radiation on microbial safety and nutritional quality of kachri (Cucumis callosus).

Fresh dried and old (6-12months) dried kachri (Cucumis callosus) were treated with 0, 2.5, 5 and 7kGy of gamma radiation in a cobalt 60 gamma cell (GC-1200). The irradiated samples of kachri were stored at room temperature (28 ± 2°C). Total bacterial count and nutrient composition were evaluated immediately after irradiation and at regular intervals of 1month during 3months of storage. Results indicated that gamma radiation reduced the total bacterial counts of dried samples of both fresh and old dried kachri. Dose of 5.0kGy was sufficient to eliminate total bacterial count and there was no microbial growth in 5.0kGy irradiated samples during the storage period. No significant differences were observed in the proximate composition of both types of kachri at all irradiation doses. It was concluded that irradiation treatments of kachri improves keeping quality of both freshly dried and old dried Kachri.

Effect of several food ingredients on radiation inactivation of Escherichia coli and Listeria monocytogenes inoculated into ground pork

The objective of this study was to examine the effects of several food ingredients on the relative radiation sensitivity (RRS) of Escherichia coli and Listeria monocytogenes inoculated onto ground pork. Garlic, leek, onion, and ginger were prepared in 3 different forms; pressurized, freeze-dried, and 70% ethanol extracted. The prepared food ingredients were subdivided into 2 groups, non-irradiated and irradiated with 5 kGy of gamma irradiation, before addition to ground pork. The prepared food ingredients were added at concentrations of 1% and 5% (w/w) into radiation-sterilized ground pork and inoculated with E. coli and L. monocytogenes (10 6 CFU/mL). For E. coli inoculated pork, the most efficient ingredient was ethanol extracted leek (RRS=3.89), followed by freeze-dried ginger and leek (RRS=3.66 and 3.63, respectively) when used without pasteurization. However, when the food ingredients were irradiation-pasteurized, the freeze-dried ginger showed the highest RRS (4.10). When 5% natural materials were added, RRS was the highest for freeze-dried and ethanol extracted onion (4.44 and 4.65, respectively). For L. monocytogenes, the RRS was relatively lower than E. coli in general. The most efficient material was pressurized and freeze-dried onion (RRS=2.13 and 2.08, respectively) at a concentration of 1%. No increase in RRS was observed at increased concentration of food ingredients. These results suggest that the addition of particular food ingredients increased the efficiency of radiation-sterilization. However, changes in RRS were dependent on the species of microorganism as well as the form of the food ingredients.

Disinfestation of stored wheat grain and flour using gamma rays and microwave heating

Samples of wheat grain and flour (20 gm of each) were infested with 20 larvae or 5 pairs of adult insects of Tribolium confusum, Lasioderma serricorne, Corcyra cephalonica or Rhyzopertha dominica. The infested samples were tested as follows : (1) microwave heating at four temperature levels 40, 45,50 and 55 °C, for exposure times from10 to 50 s; (2) gamma irradiation over the dose range of 0.5–4 KGy; (3) gamma irradiation + microwave heating. Complete kill of all stages tested was achieved at 50 °C with an exposure time of 50 s. A dose of 2 KGy induced 100% mortality of R. dominica after three days, but it took up to 7 days for all T. confusum and L. serricorne adults to die after a 4-KGy exposure. All insects died within 24 h when exposed to the combination of 1KGy + 50 °C for 30 s. Biochemical analyses on the samples of wheat grain and flour subjected to those treatments at which high mortality was obtained generally showed no detectable changes in the quality of protein, fat, fiber, carbohydrates or ash. The germination of wheat grain was lowered after treatment with microwave radiation but was not affected by a dose of 1 KGy gamma radiation.