Low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope: Monte Carlo treatment planning and dose measurements in a postmortem subject.

Objective.The goal of this study was to use Monte Carlo (MC) simulations and measurements to investigate the dosimetric suitability of an interventional radiology (IR) c-arm fluoroscope to deliver low-dose radiotherapy to the lungs.Approach.A previously-validated MC model of an IR fluoroscope was used to calculate the dose distributions in a COVID-19-infected patient, 20 non-infected patients of varying sizes, and a postmortem subject. Dose distributions for PA, AP/PA, 3-field and 4-field treatments irradiating 95% of the lungs to a 0.5 Gy dose were calculated. An algorithm was created to calculate skin entrance dose as a function of patient thickness for treatment planning purposes. Treatments were experimentally validated in a postmortem subject by using implanted dosimeters to capture organ doses.Main results.Mean doses to the left/right lungs for the COVID-19 CT data were 1.2/1.3 Gy, 0.8/0.9 Gy, 0.8/0.8 Gy and 0.6/0.6 Gy for the PA, AP/PA, 3-field, and 4-field configurations, respectively. Skin dose toxicity was the highest probability for the PA and lowest for the 4-field configuration. Dose to the heart slightly exceeded the ICRP tolerance; all other organ doses were below published tolerances. The AP/PA configuration provided the best fit for entrance skin dose as a function of patient thickness (R2 = 0.8). The average dose difference between simulation and measurement in the postmortem subject was 5%.Significance.An IR fluoroscope should be capable of delivering low-dose radiotherapy to the lungs with tolerable collateral dose to nearby organs.

Effect of Trichoderma on horticultural seedlings' growth promotion depending on inoculum and substrate type.

AIMS: The biostimulant effect of Trichoderma spp. on horticultural crops are highly variable. Thus, practical use of Trichoderma sp. requires feasible formulated products and suitable substrates. METHODS AND RESULTS: This study evaluates the survival and the growth-promotion effect of a Trichoderma saturnisporum rice formulation compared with a nonformulated conidia suspension (seven treatments in total), on tomato, pepper and cucumber seedlings grown in two substrates: (i) rich in organic matter (OM) and (ii) mineral substrate without OM. The results showed beneficial effects on seedling growth in the OM-rich substrate when T. saturnisporum rice formulation (mainly at maximum concentration) was applied, but the effects were opposite when the mineral substrate without OM was used. The effects were closely linked to the level of inoculum in the substrate, which was greater upon application of the formulated inoculum as opposed to the nonformulated one. CONCLUSIONS: The use of rice to prepare the inoculum of T. saturnisporum seems to be promising for seedling growth in the nursery when it is applied in a substrate that is rich in organic matter, but it must be considered that under certain conditions of food shortage, Trichoderma sp. could show pathogenicity to seedlings. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides evidence of the complexity inherent in the use of micro-organisms in agriculture, while also confirming that the activity of the biofertilizers based on Trichoderma depends on the type of inoculum and its concentration, as well as the properties of the medium in which the fungi develop. Further studies assessing the effectiveness or possible pathogenicity of Trichoderma in different soils under greenhouse conditions must be addressed.

First Report of Fusarium oxysporum on Sweet Pepper Seedlings in Almería, Spain.

In March of 2013, new symptoms were observed in more than seven million nursery-grown sweet pepper (Capsicum annuum) plants in El Ejido, Almería (southern Spain). Symptoms included wilting without yellowing of leaves and stunting of plants. Plant crowns exhibited necrosis that advanced through the main root along with slight root rot. Xylem was not affected above or below the crown. Symptoms were thought to be caused by the well-known pepper pathogen Phytophthora capsici. However, sporodochia of Fusarium oxysporum were observed on plant crowns. Symptomatic seedlings (n = 200) were sampled and analyzed. Tissue from roots and epidermal crowns were plated on PDA, PARP, and Komada media, as well as stem discs on PDA and Komada. No Phytophthora sp. were observed and F. oxyporum was exclusively isolated from all 200 samples, from roots and crowns, but not from xylem. Pathogenicity of 60 of these F. oxysporum isolates was studied by inoculation onto sweet pepper plants (cv. del Piquillo) at the 2-true-leaf stage. Twelve plants per isolate, grown on autoclaved vermiculite, were inoculated by drenching with 20 ml of a conidial suspension (1 × 105 CFU/ml) of each isolate per plant. Each suspension was obtained by blending one PDA petri dish fully covered with one isolate. Non-inoculated plants served as control. Plants were maintained for 30 days in a growth chamber with a 14-h photoperiod (1.6 ×·104 lux) and temperatures at 23 to 26°C. The assay was conducted twice. Symptoms described above were reproduced on crown and roots of the inoculated plants with no symptoms in stem discs. No symptoms were observed on controls after 48 days. Host specificity was tested for 13 isolates to tomato (Solanum lycopersicum) cv. San Pedro, eggplant (S. melongena) cv. Alegria, cucumber (Cucumis sativus) cv. Marketmore, watermelon (Citrullus lanatus) cv. Sugar Baby, and Chinese cabbage (Brassica campestris subsp. condensa) cv. Kasumi (4). These plants were inoculated as previously described for pathogenicity tests (12 plants per species, repeated twice). None of the plants exhibited the characteristic symptoms after 60 days. Five isolates of F. oxysporum f. sp. radicis-cucumerinum and four isolates of F. o. f. sp radicis-lycopersici were also inoculated without any symptoms in any of the inoculated sweet pepper plants. Morphological identity of all isolates corresponded to F. oxysporum. The fungi were identified following the morphological keys and methodology provided by (1) and (2). Three isolates from the 60 tested were selected for molecular identification. Molecular identification was performed by sequencing partial TEF-1α gene (3). Subsequent database searches by BLASTn indicated that the resulting sequence of 659-bp had 100% identity with the corresponding gene sequence of F. oxysporum. The sequences were identical for the three isolates and were deposited on the EMBL Sequence Database (HG916993, HG916994, and HG916995). Results suggest that the pathogenic ability of the isolates varies from a vascular Fusarium wilt. F. oxysporum f. sp. capsici is a reported pathogen to sweet pepper (5), but the symptoms we have found are closer to those manifested by the formae speciales that causes root and crown rot of other plants. Consistent with the convention stablished for similar diseases we propose the name F. oxysporum f. sp. radicis-capsici f. sp. nov. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell, Ames, IA, 2006. (2) P. E. Nelson et al. Fusarium species. An Ilustrated Manual for Identification. The Penn St. University Press, 1983. (3) K. O'Donnell et al. Proc. Nat. Acad. Sci. 95:2044, 1998.(4) L. M. Oelke and P. W. Bosland. Capsicum Eggplant Newsl. 20:86, 2001. (5) V. C. Rivelli. M.S. Thesis. Dep. Plant Pathol. and Crop Phys. Louisiana State Univ., Baton Rouge, 1989.

Long-term follow-up of radiation accident patients in Peru: review of two cases.

Overexposure to radioactive sources used in radiotherapy or industrial radiography may result in severe health consequences. This report assesses the initial clinical status and the medical and psychological long-term follow-up of two radiation accident patients from Peru during the mid-to-late 1990s: one patient exposed to a radiotherapy (60)Co source in Arequipa, the other patient to a (192)Ir source in Yanango. Commonalities and differences are described. The main causes in both accidents were human error and the failure to apply appropriate safety guidelines and standard operating procedures. Education and training of the personnel working with radiation sources are essential to prevent accidents. The experience gained from the medical management of the two patients is valuable for future treatment of such patients.

Evaluation of alternatives to methyl bromide in melon crops in Guatemala.

The monoculture of melon in Guatemala has caused the massive appearance of plants with an analogous syndrome for the well-known disease commonly called melon collapse, or vine decline, causing significant losses in crops. Methyl bromide is commonly used to sterilize soil prior to planting in Guatemala, but it must be phased out by 2015. The objective of this study was to evaluate the technique of grafting melon onto hybrids of Cucurbita (Cucurbita maxima x Cucurbita moschata), as an alternative to using soil disinfectants (such as Metam sodium, 1,3-dichloropropene, and methyl bromide) for the control of collapse. The results suggested that both soil disinfection and grafting were not necessary in these locations, since there were no statistical differences in terms of yields between the treatments and the untreated control. Furthermore, these results demonstrate that decisions to disinfect the soil must be based on the firm identification of the causal agents, in addition to preliminary assessments of yield losses.

Effects of water potential on spore germination and viability of Fusarium species.

Germination of macroconidia and/or microconidia of 24 strains of Fusarium solani, F. chlamydosporum, F. culmorum, F. equiseti, F. verticillioides, F. sambucinum, F. oxysporum and F. proliferatum isolated from fluvial channels and sea beds of the south-eastern coast of Spain, and three control strains (F. oxysporum isolated from affected cultures) was studied in distilled water in response to a range of water potentials adjusted with NaCl. (0, -13.79, -41.79, -70.37, -99.56 and -144.54 bars). The viability (UFC/ml) of suspensions was also tested in three time periods (0, 24 and 48 h). Conidia always germinated in distilled water. The pattern of conidial germination observed of F. verticilloides, F. oxysporum, F. proliferatum, F. chlamydosporum and F. culmorum was similar. A great diminution of spore germination was found in -13.79 bars solutions. Spore germination percentage for F. solani isolates was maximal at 48 h and -13.79 bars with 21.33% spore germination, 16% higher than germination in distilled water. F. equiseti shows the maximum germination percentage in -144.54 bars solution in 24 h time with 12.36% germination. This results did not agree with those obtained in the viability test were maximum germination was found in distilled water. The viability analysis showed the great capacity of F. verticilloides strains to form viable colonies, even in such extreme conditions as -144.54 bars after 24 h F. proliferatum colony formation was prevented in the range of -70.37 bars. These results show the clear affectation of water potential to conidia germination of Fusaria. The ability of certain species of Fusarium to develop a saprophytic life in the salt water of the Mediterranean Sea could be certain. Successful germination, even under high salty media conditions, suggests that Fusarium spp. could have a competitive advantage over other soil fungi in crops irrigated with saline water. In the specific case of F. solani, water potential of -13.79 bars affected germination positively. It could indicate that F. solani has an special physiological mechanism of survival in low water potential environments.

The interactive effects of temperature and osmotic potential on the growth of marine isolates of Fusarium solani.

The mycelial growth of 18 Fusarium solani strains isolated from sea beds of the south-eastern coast of Spain was tested on potato-dextrose-agar adjusted to different osmotic potentials with either KCl or NaCl (-1.50 to -144.54 bars) in 10 degrees C intervals ranging from 15 to 35 degrees C. Fungal growth was determined by measuring colony diameter after 4 days of incubation. Mycelial growth was maximal at 25 degrees C. The quantity and frequency pattern of mycelial growth of F. solani differ significantly at 15 and 25 degrees C, with maximal growth occurring at the highest water potential tested (-1.50 bars); and at 35 degrees C, with a maximal mycelial growth at -13.79 bars. The effect of water potential was independent of salt composition. The general growth pattern of F. solani showed declining growth at potentials below -41.79 bars. Fungal growth at 35 degrees C was always higher than that grow at 15 degrees C, of all the water potentials tested. Significant differences observed in the response of mycelia to water potential and temperature as main and interactive effects. The viability of cultures was increasingly inhibited as the water potential dropped, but some growth was still observed at -99.56 bars. These findings could indicate that marine strains of F. solani have a physiological mechanism that permits survival in environments with low water potential. The observed differences in viability and the magnitude of growth could indicate that the biological factors governing potential and actual growth are affected by osmotic potential in different ways.

First Report of Fulvia fulva, Causal Agent of Tomato Leaf Mold, in Greenhouses in Southeastern Spain.

Tomato (Solanum lycopersicum L.) is produced in more than 9,000 ha of greenhouses in Almería (southeastern Spain). During 2006 and 2007, a new disease was observed on almost all plants in 37 greenhouses. Yellow spots on upper and lower leaf surfaces were accompanied by gray-to-dark brown mycelia, conidiophores, and conidia on lower leaf surfaces. Affected leaves became necrotic and withered. Six isolates grown on malt extract agar (MEA) were identified as Fulvia fulva (1). The one- to three-celled conidia ranged from 21.8 × 7.8 µm to 21.5 × 6.5 µm. On MEA, potato dextrose agar, and V8 juice agar, the pathogen grew slowly; colonies were only 1 cm in diameter after 30 days. Colony color was initially intense yellow but became dark brown with age. In a growth chamber (12,000 lux for 16 h per day, 23 to 28°C, and 60 to 95% relative humidity), six pots containing five tomato plants (cv. SanPedro) at the four-true-leaf stage were inoculated with a conidial suspension (103 CFU/ml) of F. fulva. Control plants were sprayed with water. The trial was repeated once. Immediately after inoculation, plants were sealed in plastic bags for 8 days. Symptoms of the disease and signs of the pathogen were observed on all inoculated plants 18 days after inoculation. To our knowledge, this is the first report of leaf mold of tomato in Almería and it is becoming common in the greenhouse industry in this region. Reference: (1) P. Holliday and J. L. Mulder. No. 487 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1976.

Association of Pythium aphanidermatum with Root and Crown Rot of Melons in Honduras.

Approximately 10,000 ha of melon (Cucumis melo L.), primarily cantaloupe and honeydew types, are grown in Honduras for export to U.S. markets. In 2004 and 2005, several soil surveys were conducted in areas with a history of vine decline. Twenty-nine soil samples from six farms were collected from the rhizosphere of wilted plants. Thirty-six melon plants were planted in a mixture of each rhizosphere sample and vermiculite (1:6 v/v). The plants were maintained in a growth chamber at 23 to 25°C with a 16-h photoperiod. The first symptoms, which appeared at the one- or two-true-leaf stage, were girdling of the lower stem, leaf chlorosis, and wilting. Affected plants exhibited necrotic crowns and roots and half of all plants died less than 3 days after wilting. Isolations from washed and dried crown and roots pieces from affected plants were placed on malt extract agar. Colonies were transferred to potato carrot agar and into dishes of sterile water and immature carnation petals to aid in the identification of recovered fungi. Nearly 500 isolates of Pythium species were cultured, and approximately 60% were identified as P. aphanidermatum (Edson) Fitzp. on the basis of their toruloid sporangia, aplerotic oospores, terminal and smooth oogonia, monoclinous sac-shaped antheridia (one to two per oogonium), and abundant appressoria. The pathogenicity of nine isolates was confirmed in a growth chamber. Ten plants of melon cv. Amarillo Canario, grown in sterilized vermiculite, were inoculated at the two- or three-true-leaf stage by drenching pots with 100 ml of a suspension of each isolate (103 CFU ml-1). Noninoculated plants served as controls. There were three replicates per isolate. Plants began to die 7 days after inoculation and the incidence of the affected plants reached an average of 70%. P. aphanidermatum causing decline of melon plants has been previously reported in hot and semi-arid areas in Israel and Spain (1,2). To our knowledge, this is the first report of P. aphanidermatum pathogenic to melon plants in Honduras. References: (1) S. Pivonia et al. Plant Dis. 81:1264, 1997. (2) J. Gómez Enfermedades del Melón en los Cultivos "Sin Suelo" de la Provincia de Almería. Junta de Andalucía, 1993.

Detection of Fusarium oxysporum f. sp. melonis Race 1 in Soil in Colima State, Mexico.

During the winters of 2002 and 2003, a wilt occurred in melons cultivated on 1,500 ha in Colima State, Mexico. Yield losses reached 25% of final production, despite soil disinfestation with 60% methyl bromide and 40% chloropicrin. On the basis of the observation of plants with necrotic xylem, yellowing, and wilting of leaves, this disease was identified provisionally as Fusarium wilt. During February 2003, four soil samples from affected fields were plated onto a Fusarium-selective medium (1), which resulted in the detection of 2,260 ± 357, 179 ± 76, 668 ± 357, and 1,391 ± 256 CFU/g of F. oxysporum (3). Thirty-one randomly chosen isolates were used to inoculate differential cultivars of melon as described by Risser et al. (4). The cultivars were Amarillo Canario (susceptible to all races), Diana (resistant to races 0 and 2), Tango (resistant to races 0 and 1), and Vulcano (resistant to races 0, 1, and 2) (2). Ten plants of each cultivar, grown on sterilized vermiculite, were inoculated at the first true-leaf stage by drenching with 200 ml of a conidial suspension (1 × 105 CFU/ml) of each isolate. Noninoculated plants of each cultivar served as controls. Plants were maintained in a growth chamber with a 16-h photoperiod (18 × 103 lux) and temperatures at 23 to 25°C. Yellowing, wilt, and vascular discoloration symptoms developed on cvs. Amarillo Canario and Diana following inoculation with each of the 31 isolates, while noninoculated plants remained symptomless. F. oxysporum was consistently reisolated on potato dextrose agar from the affected plants. On the basis of the combination of affected cultivars, all isolates were identified as F. oxysporum f. sp. melonis race 1. To our knowledge, this is the first report of F. oxysporum f. sp. melonis race 1 in Colima State, Mexico. References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) J. Marín Rodríquez. Portagrano 2004. Vadmecum de Variedades Hortícolas. Agrobook, Spain. 2004. (3) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park, 1983. (4) G. Risser et al. Phytopathology 66:1105, 1976.

First Report of Blue Mold or Downy Mildew of Pepper from Nurseries in Southeastern Spain.

During October and November 2001, four nurseries reported severe losses in production of pepper seedlings (Capsicum annuum). Plants were affected with the following symptoms: chlorotic spots on upper leaf surfaces along with a dark brown felt and violet reflections on the undersurface of leaves. Spots became necrotic and expanded to include almost the entire blade prompting defoliation that made the plants worthless. These disease symptoms had not been observed in Spain previously. At least four pepper seedbeds were affected and 1.6 million plants (>40% total production) suffered severe defoliation. California type cultivars that produce yellow fruit (Capino, Vélea, and Fiesta) exhibited more severe symptoms compared with cultivars that produce red fruit (Orlando, Haban, Barbadillo, Ribera, and Requena). Lamuyo type cultivars were not severely diseased. Identification of the parasitic fungus from leaves revealed that Peronospora tabacina was the causal agent of downy mildew in pepper, the same pathogen known as the causal agent of tobacco blue mold. Sexual reproductive structures were not found on pepper leaves. Sporangia and sporangiophores corresponded with those described for P. tabacina (synonym P. hyoscyami f. sp. tabacina) (3). The shape of sporangia was spherical in the youngest sporangia and oval to elliptical in mature sporangia (23 × 16 µm). Sporangia were borne on dendritic, dichotomously branched sporangiophores that branched four to eight times and terminated in curved, acute apices. Sporangiophores occurred singly or in small groups. Pathogenicity tests were conducted on California and Lamuyo type pepper cultivars. An inoculum suspension prepared by washing leaves with distilled water was sprayed on seedlings with four true leaves. Inoculated seedlings were maintained at temperatures of 15 to 25°C (night/day). P. tabacina exhibiting the same morphological features as those described above was observed 15 days later on pepper leaves. This disease on pepper was described first in the United States (1,2) and subsequently reported in Greece and Australia (2). The fungus caused disease in nurseries producing pepper seedlings following production of tobacco seedlings or close to other tobacco plants (1). In Murcia, this downy mildew in pepper appeared in pepper nurseries with supplemental heating and did not appear in those without heating. However, the disease spread when diseased pepper seedlings were moved to nonheated nurseries greenhouses. The inoculum may originate from tobacco plants introduced in the greenhouses for the purpose of propagating parasites of whitefly (Bemisia tabaci). Otherwise, tobacco is not cultivated in the Murcia region. References: (1) G. M. Armstrong and W. B. Albert. Plant Dis. Rep. 17:37, 1933. (2) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory, On-line publication. http://nt.ars-grin.gov/fungaldatabases/databaseframe.cfm. August 2, 2002. (3) G. Hall. Peronospora hyoscyami f. sp. tabacina. No. 975 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1989.

First Report of Fusarium oxysporum f. sp. basilici in Sweet Basil Cultivation in Spain.

Recently, sweet basil (Ocimum basilicum L.) grown in greenhouses was introduced in Almería, Spain. It is typically cultivated in soil or perlite soilless culture. During the last 6 years, the following symptoms were observed sequentially in basil cultivation: yellowing and wilting of apical tips, wilting and necrosis of leaves and petioles, stunting, black lines along stems and petioles, and discoloration and necrosis of the xylem. Symptoms began at the apex and progressed to the plant base. Within 4 months of planting, symptoms developed in more than 14% of soil-cultivated plants, and in more than 13% of perlite-cultivated plants. Isolations from diseased xylem revealed the presence of Fusarium oxysporum. Inoculations were performed with a fungal suspension (104 CFU/ml) on basil cv. Genovesa, by drenching plants grown in sterile substrate or dipping the roots and transplanting plants into sterile substrate. Of 30 isolates, 80% were pathogenic and resulted in symptoms of the disease described above. The pathogen was reisolated from all inoculated plants. Inoculating Melissa officinalis L., Salvia officinalis L., Origanum majorana L., Mentha piperita L., Satureja hortensis L., and Thymus vulgaris L tested specificity of F. oxysporum. This test utilized the same methods used for basil. None of these species developed symptoms. Results indicated that symptoms of the disease on basil were caused by F. oxysporum f. sp. basilici. Since cultivation of basil is relatively new to Almería, it was necessary to determine the source of the inoculum. Accordingly, 3,200 seeds from Germany and Italy, the primary source of seed in Almería, were analyzed. F. oxysporum was isolated from 0.5% of the seeds. Following methods used earlier, all isolates were inoculated on basil. Fifty percent of the isolates reproduced the disease symptoms. The results suggest that the seeds from Germany and Italy were the source of the inoculum, and to our knowledge, introduced the disease into the growing basil cultures of Almería.