Gamma ray irradiation (Co60) of lulo with and without thorns calluses and seedlings (Solanum quitoense Lam.) produced in vitro

The cultivation of lulo de Castilla (Solanum quitoense Lam.) in Colombia is subject to a series of sanitary problems, which has forced many producers to abandon the crop as a result of the total loss of plantations or to transfer the crop to new areas. It is necessary to implement breeding programs in order to produce varieties that are tolerant to the limiting problems. Since these programs require broad genetic variability in the progenitors, the present study aimed to evaluate the possibility of inducing in vitro variability in explants subjected to different doses of gamma radiation using a Co60 source. The evaluated radiation doses were 0 Gy, 15 Gy, 30 Gy, 45 Gy, and 60 Gy in calluses induced with cotyledonary leaves and in seedlings from in vitro cultures of lulo with and without thorns. The survival and regeneration potential were also evaluated. The calluses were the explants that showed the highest survival, and the lulo seedlings without thorns were the most radiosensitive with a mortality of 100% at a dose of 30 Gy. The lulo seedlings with thorns had 100% mortality at a dose of 45 Gy. The irradiated lulo seedlings with thorns had a greater regeneration capacity than the lulo without thorns, with 1.52 seedling per explant and 1.12 seedling per explant, respectively, and the RAM markers showed genetic variability in all the irradiation treatments.

Utilization of Acetyl Salicylic Acidand Irradiation as Postharvest Treatments for Storage of Persimmon Fruits Cv."Costata"

Mature Persimmon fruits "Costata cv." were used to study the effect of Acetyl Salicylic Acid (ASA) at rates 0, 2, 3% and/or irradiation (IRD) with 0.0, 1.0, 2.0 KGy doses, using CO60 source at 2g /Sec as a trial for prolonging fruit marketing period and extending its shelf life with good quality, after cold storage treatment. Nine treatments including control were stored for 75 days at 0 ± 1oC with 80 + 2% relative humidity to measure weight loss, fruit firmness and decay percentages. Where, fruit quality parameters during shelf life were evaluated after 7 days of transference to room temperature (23 ± 2°C). Results showed a close relationship between high irradiation dose (2 KGy) and rate of detrimental effects by accelerating ripening process and softening during storage and shelf life to obtain less marketing fruits. Adding ASA at either 3 or 2% to fruits irradiated with2 KGy, slightly reduced the decline in fruit quality. Furthermore, non-treated cold stored fruits dominated 2 KGy treatment, in this respect.However, fruit constituent values were gradually progressed and 1 KGy dose recorded the highest storability effect in keeping fruits firm with less deterioration response as combined with 2% ASA, compared with sole ones.Moreover, improving effect in fruit components i.e., acidity, VC, SSC, sugar, T. flavonoids, β-Carotene and reduction in tannin contents were retained with 1 KGy treatment as combined with 2% ASA followed in descending order by 3% ASA. In general, irradiation of persimmon fruits at dose (2 KGy) was not suitablefor preserving stored fruits. Also, sole radiation treatment at 1 KGy was less effective than sole treatment of ASA at either 2 or 3% rates, in this respect. Therefore, irradiation with 1 KGy combined with ASA treatment at 2% can be recommended for improving storability of persimmon"Costata cv." fruits with the maintenance of good marketable and preferable nutritional parameters up to extended shelf life.

A Matrix-Inversion Method for Gamma-Source Mapping From Gamma-Count Data

In a previous paper (1) it was proposed that a simple matrix inversion method could be used to extract source distributions from gamma-count maps, using simple models to calculate the response matrix. The method was tested using numerically generated count maps. In the present work a 100 kBq Co60 source has been placed on a gridded surface and the count rate measured using a NaI scintillation detector. The resulting map of gamma counts was used as input to the matrix inversion procedure and the source position recovered. A multisource array was simulated by superposition of several single-source count maps and the source distribution was again recovered using matrix inversion. The measurements were performed for several detector heights. The effects of uncertainties in source-detector distances on the matrix-inversion method are also examined. The results from this work give confidence in the application of the method to practical applications, such as the segregation of highly active objects amongst fuel-element debris.

Electron Beam and Gamma Irradiation Effectively Reduce Listeria monocytogenes Populations on Chopped Romaine Lettuce

Fresh, chopped romaine lettuce contaminated with a seven-strain cocktail of Listeria monocytogenes (in a solution containing approximately 108 organisms per ml) that had attained a level of contamination of between 7 and 8 log CFU/g was packaged in 15-g samples. The lettuce was irradiated with a Co60 source at 1.15 or 0.51 kGy and then stored at 4°C. In addition, samples contaminated with isolated strains 16397, 0733, and 1992 were subjected to either electron beam irradiation at doses ranging from 0.3 to 1.2 kGy or gamma irradiation at 0.56 kGy without subsequent refrigerated storage. All postir-radiation and control samples were diluted with Butterfield's phosphate buffer and plated in duplicate on modified Oxford media. Samples that received electron beam or gamma irradiation without subsequent refrigerated storage were also plated in duplicate on modified Oxford media plates coated with two 7-ml layers of basal yeast extract agar. Electron beam irradiation yielded D10-values (the dose required to eliminate 90% of the microbial population) of 0.16, 0.17, and 0.19 kGy for strains 16397, 0733, and 1992, respectively. The corresponding log reductions obtained for these same three strains at 0.56 kGy of gamma irradiation were 2.91, 2.62, and 2.66 log, respectively. Gamma irradiation at 1.15 and 0.51 kGy with subsequent refrigerated storage (4°C) reduced populations by >5 and >2 log, respectively, compared with controls. Neither the irradiated samples nor the control samples showed increases in population during the storage periods. Our results indicate that low-dose irradiation can effectively reduce or eliminate L. monocytogenes on chopped romaine lettuce, improving the safety of ready-to-eat salads.

Single Administration of Antiapoptotic Cytokines Soon after High Dose Irradiation Prevents Monkeys from Thrombocytopenia.

Preservation of hematopoietic stem and progenitor cell survival is required for recovery from radiation-induced myelosuppression. We recently showed the capacity of a single injection of antiapoptotic cytokines, namely stem cell factor, FLT-3 ligand, megakaryocyte growth and development factor, and interleukin-3 in combination (4F, each factor given intravenously at 50 μg/kg) administered shortly after a 5 Gy gamma total body irradiation to prevent monkeys from myelosuppression. As cytokine efficacy depends on the residual stem cell pool, the aim of the present study was to assess the efficacy of 4F in case of high dose irradiation. Adult monkeys (n=7) were globally and frontally irradiated at 7 Gy gamma using a Co60 source (dose rate 20 cGy/mn). Three animals received 4F 2 hours after irradiation and four control animals were injected with the diluant at the same time. Moreover, one of the treated monkeys was grafted with allogeneic mesenchymal stem cells (MSC) to enhance hematopoietic recovery. Human MSCs were infused directly in humerus simultaneously with 4F injection, allowing cell tracking. Treated monkeys experienced a very short period of thrombocytopenia as compared with untreated animals (platelet [PLT] count < 20 x 109/L: 1 ± 1.7 day versus 27 ± 18 days). Areas under the curve (AUC) of PLTs and red blood cells (RBCs) between days 0 and days 90 were higher in treated animals than in controls. The animal treated with 4F + MSC did not differ from the two 4F monkeys. In contrast with 5 Gy irradiated animals previously studied, both treated and untreated monkeys experienced a prolonged period of neutropenia (neutrophil [ANC] count < 0.5 x 109/L: 12 ± 3 days versus 10.3 ± 7.3) and AUCs of ANC did not significantly differ. This study shows that the 4F treatment, as a single dose regimen, prevents thrombocytopenia in high dose irradiation setting and could act as an emergency treatment for nuclear accident or terrorism victims.

FLT-3 Ligand Provides Hematopoietic Protection From Total Body Irradiation in Rabbits

Several hematopoietic cytokines have been investigated for their potential to provide protection from the lethal consequences of bone marrow aplasia after total body irradiation (TBI). Some can increase the dose of irradiation tolerated by the animals; none allow endogenous recovery after doses such as administered in clinical blood or marrow transplantation. We tested the radioprotective potential of FLT-3 ligand, an early acting hematopoietic cytokine, alone and in combination with a late acting cytokine, granulocyte-colony stimulating factor (G-CSF). Adult outbred New Zealand White rabbits were submitted to TBI of 1,200 or 1,400 cGy by a Co60 source. Recombinant human (rh) FLT-3 ligand at a dose of 500 μg/kg and/or rhG-CSF at a dose of 10 μg/kg were administered for 14 days subcutaneously daily, beginning either 2 days before or the day after TBI. All control animals given no growth factors died of aplasia at day 10 (range, 5 to 16). All 8 animals given G-CSF had severe aplasia and 7 died at day 8 (range, 5 to 10); 1 animal survived, with G-CSF being administered before TBI. In contrast, 11 of 12 animals given FLT-3 ligand, with or without G-CSF, survived. Radioprotection was best in the group given FLT-3 ligand together with G-CSF before TBI. In these animals median platelet counts were never <10 × 109/L and median white blood cell counts never <0.5 × 109/L. These data show that hematopoietic recovery can occur after 1,400 cGy TBI in rabbits, if protected by FLT-3 ligand, and suggest a radioprotective clinical potential of this cytokine. © 1998 by The American Society of Hematology.

FLT-3 Ligand Provides Hematopoietic Protection From Total Body Irradiation in Rabbits

Several hematopoietic cytokines have been investigated for their potential to provide protection from the lethal consequences of bone marrow aplasia after total body irradiation (TBI). Some can increase the dose of irradiation tolerated by the animals; none allow endogenous recovery after doses such as administered in clinical blood or marrow transplantation. We tested the radioprotective potential of FLT-3 ligand, an early acting hematopoietic cytokine, alone and in combination with a late acting cytokine, granulocyte-colony stimulating factor (G-CSF). Adult outbred New Zealand White rabbits were submitted to TBI of 1,200 or 1,400 cGy by a Co60 source. Recombinant human (rh) FLT-3 ligand at a dose of 500 μg/kg and/or rhG-CSF at a dose of 10 μg/kg were administered for 14 days subcutaneously daily, beginning either 2 days before or the day after TBI. All control animals given no growth factors died of aplasia at day 10 (range, 5 to 16). All 8 animals given G-CSF had severe aplasia and 7 died at day 8 (range, 5 to 10); 1 animal survived, with G-CSF being administered before TBI. In contrast, 11 of 12 animals given FLT-3 ligand, with or without G-CSF, survived. Radioprotection was best in the group given FLT-3 ligand together with G-CSF before TBI. In these animals median platelet counts were never <10 × 109/L and median white blood cell counts never <0.5 × 109/L. These data show that hematopoietic recovery can occur after 1,400 cGy TBI in rabbits, if protected by FLT-3 ligand, and suggest a radioprotective clinical potential of this cytokine. © 1998 by The American Society of Hematology.

Oxygen-centred free radicals can efficiently degrade the polypeptide of proteoglycans in whole cartilage

Bovine nasal cartilage slices, biosynthetically labelled in their proteoglycan with35SO4, were used as substrate for the attack of free radicals generated on exposure to a Co60 source (which allows study of single radical species), and by chemical and enzymatic means. Systems generating hydroxyl (OH•) and superoxide (02•-) radicals degraded the proteoglycan efficiently, while the hydroperoxy radical (HO2•) was less efficient; addition of appropriate radical scavengers inhibited degradation. The radioactive products were heterogeneous in molecular size, but with doses up to 3600 Gy were the same size range as intact chondroitin sulphate. They contained free amino groups, and more were liberated by aminopeptidase M digestion, implying that at least a small peptide was present. Thus a major site of radical attack may be the polypeptide chain. We suggest that free-radical fragmentation of polypeptides may be important both in extracellular catabolism and in intracellular proteolysis.