RESUMEN
Hand-held, portable X-Ray fluorescence instruments (pXRF) provide a means of rapid, in-situ chemical characterisation that has considerable application as a rapid trace evidence characterisation tool in forensic geoscience. This study presents both a control test study which demonstrates optimisation of the data collection process, alongside a range of individual forensic case studies, including heavy metal contamination, conflict archaeology, forensic soil characterisation, and verification of human remains, which together validate the technique and provide some comparison between field-based and laboratory-based pXRF applications. Results highlight the time-efficiency and cost-effectiveness of in-situ, field-based pXRF analyses for material characterisation when compared with other trace evidence methods. Analytical precision of various analytes during in-situ analysis was sufficient to demonstrate considerable application of field-based pXRF as a tool for rapid identification of specific areas of interest to be further investigated. Laboratory-based pXRF analyses yielded greater accuracy which could provide an efficient compromise between field-based pXRF and traditional laboratory-based analytical techniques (e.g. WD-XRF, ICP-MS). Further studies should collect more advanced datasets in more diverse locations to further validate the techniques capability to rapidly conduct geochemical surveys in a range of environments.
Asunto(s)
Ciencias Forenses/instrumentación , Contaminantes del Suelo , Espectrometría por Rayos X/instrumentación , Crimen , Ciencias de la Tierra , Humanos , Contaminantes del Suelo/análisisRESUMEN
While dihydrofolate reductase (DHFR) is an important drug target in mammals, bacteria and protozoa, no inhibitors of this enzyme have been developed as commercial insecticides. We therefore examined the potential of this enzyme as a drug target in an important ectoparasite of livestock, the Australian sheep blow fly, Lucilia cuprina (Diptera: Calliphoridae) (Wiedemann). The non-specific DHFR inhibitors aminopterin and methotrexate significantly inhibited the growth of L. cuprina larvae, with IC50 values at µg levels. Trimethoprim and pyrimethamine were 5-30-fold less active. Relative IC50 values for the inhibition of recombinant L. cuprina DHFR by various inhibitors were in accordance with their relative effects on larval growth. The active-site amino acid residues of L. cuprina DHFR differed by between 34% and 50% when compared with two mammalian species, as well as two bacteria and two protozoa. There were significant charge and size differences in specific residues between the blow fly and human DHFR enzymes, notably the L. cuprina Asn21, Lys31 and Lys63 residues. This study provides bioassay evidence to highlight the potential of blow fly DHFR as an insecticide target, and describes differences in active site residues between blow flies and other organisms which could be exploited in the design of blow fly control chemicals.
Asunto(s)
Dípteros/efectos de los fármacos , Dípteros/genética , Insecticidas/farmacología , Proteínas Recombinantes/genética , Tetrahidrofolato Deshidrogenasa/genética , Secuencia de Aminoácidos , Animales , Clonación Molecular , Dípteros/crecimiento & desarrollo , Dípteros/metabolismo , Activación Enzimática/efectos de los fármacos , Regulación Enzimológica de la Expresión Génica , Concentración 50 Inhibidora , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Larva/efectos de los fármacos , Larva/genética , Larva/metabolismo , Datos de Secuencia Molecular , Pupa/efectos de los fármacos , Pupa/genética , Pupa/metabolismo , Proteínas Recombinantes/metabolismo , Alineación de Secuencia/veterinaria , Tetrahidrofolato Deshidrogenasa/metabolismoRESUMEN
Rhagodia preissii had shown significant in vitro anthelmintic activity in a previous study, we examined the effect of including this shrub in the diet of sheep infected with Trichostrongylus colubriformis. Worm-infected merino wethers were grazed for 7 weeks on either R. preissii or annual pasture, and faecal egg counts (FECs) were conducted weekly. Plant material was collected weekly from eaten and uneaten plants, and analysed for levels of plant secondary metabolites (tannins, oxalates, saponins) and in vitro anthelmintic activity. While mean FECs were consistently lower in sheep grazing R. preissii compared to pasture (reductions of 20-74%), the differences were not significant. There was no relationship between grazing preference (eaten or uneaten) and in vitro anthelmintic activity of plant extracts. The levels of saponins and oxalates did not correlate with grazing preference or in vitro anthelmintic activity, while tannins were not responsible for the anthelmintic activity. While the identity of the grazing deterrent and in vitro anthelmintic compounds remain unknown, the presence of plants which were both highly preferred by the sheep and showed in vitro anthelmintic activity indicates a potential to develop the species as an anthelmintic shrub through selection of shrub populations dominated by such plants.
Asunto(s)
Amaranthaceae/química , Antihelmínticos/uso terapéutico , Fitoterapia/veterinaria , Extractos Vegetales/uso terapéutico , Enfermedades de las Ovejas/prevención & control , Tricostrongiliasis/veterinaria , Alimentación Animal , Animales , Antihelmínticos/análisis , Antihelmínticos/farmacología , Dieta/veterinaria , Heces/parasitología , Conducta Alimentaria , Masculino , Oxalatos/análisis , Oxalatos/farmacología , Recuento de Huevos de Parásitos/métodos , Recuento de Huevos de Parásitos/veterinaria , Extractos Vegetales/análisis , Extractos Vegetales/farmacología , Saponinas/análisis , Saponinas/farmacología , Ovinos , Enfermedades de las Ovejas/tratamiento farmacológico , Enfermedades de las Ovejas/parasitología , Taninos/análisis , Taninos/farmacología , Tricostrongiliasis/tratamiento farmacológico , Tricostrongiliasis/parasitología , Tricostrongiliasis/prevención & control , Trichostrongylus/efectos de los fármacos , Trichostrongylus/crecimiento & desarrollo , Trichostrongylus/patogenicidadRESUMEN
In this case, an individual was suspected of attempting to burn materials potentially relating to a murder case. A number of spent and unspent matches were seized at the scene by police for forensic examination. Coincidentally, a police raid at the suspect's house revealed a number of matchboxes, all of the same brand, containing matches that had a visual similarity to those recovered at the scene. Stable Isotope Profiling (SIP) was used to assess whether matches could either be distinguished or shown to be indistinguishable by 13C and 2H isotopic composition. These results were then compared to those from the X-ray diffraction (XRD) analysis of match heads and microscopy of the wood. SIP showed the scene matches and seized matches to be different, which was confirmed by XRD and microscopy analyses.