Imaging of Biological Tissues by Desorption Electrospray Ionization Mass Spectrometry

Mass spectrometry imaging (MSI) provides untargeted molecular information with the highest specificity and spatial resolution for investigating biological tissues at the hundreds to tens of microns scale. When performed under ambient conditions, sample pre-treatment becomes unnecessary, thus simplifying the protocol while maintaining the high quality of information obtained. Desorption electrospray ionization (DESI) is a spray-based ambient MSI technique that allows for the direct sampling of surfaces in the open air, even in vivo. When used with a software-controlled sample stage, the sample is rastered underneath the DESI ionization probe, and through the time domain, m/z information is correlated with the chemical species'' spatial distribution. The fidelity of the DESI-MSI output depends on the source orientation and positioning with respect to the sample surface and mass spectrometer inlet. Herein, we review how to prepare tissue sections for DESI imaging and additional experimental conditions that directly affect image quality. Specifically, we describe the protocol for the imaging of rat brain tissue sections by DESI-MSI.     

Combination of solvent and radiation effects on degradation of aflatoxin B1

Summary Degradation of aflatoxin B₁ in chloroform, ethyl ccetate and coconut oil were examined by exposing the solvents in the form of thin layers to radiation from the sun and from UV and fluorescent tubes. Solar degradation of aflatoxin B₁ occurred in coconut oil leaving no residual aflatoxin B₁ or any new fluorescent derivatives. Other combinations of solvents and radiation produced up to four new fluorescent degradation compounds. Aflatoxin B₁ did not undergo solar degradation in the absence of moisture. Acidity enhanced solar degradation. A fluorescent derivative produced by solar degradation of aflatoxin B₁ in chloroform degraded further on solar irradiation in coconut oil but not in chloroform.

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Resumen Se examinó la degradación de la aflatoxina B1 en cloroformo, acetato de etilo y aceite de coco, exponiendo los disolventes en forma de capa fina a la radiación solar y a radiaciones procedentes de lámparas UV y fluorescentes. La degradación solar de la aflatoxina B1 tuvo lugar en aceite de coco sin dejar residuos de aflatoxina ni de ningún nuevo derivado fluorescente. Otras combinaciones de disolvente y radiaciones produjeron hasta 4 nuevos derivados fluorescentes. La degradación solar de la aflatoxina B1 no se produjo en ausencia de humedad. La acidez potenció la degradación solar. Uno de los derivados fluorescentes obtenidos en la degradación solar de la aflatoxina B1 en cloroformo continuó degradándose bajo la radiación solar en aceite de coco pero no en cloroformo.

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Résumé La dégradation de l'aflatoxine B1 dans le chloroforme, l'acétate d'éthyle et l'huile de noix de coco a été examinée en exposant les solvents sous la forme de films minces à l'irradiation du soleil, des uv et de tubes fluorescents. La dégradation solaire de l'aflatoxine B1 s'est produite dans l'huile de noix de coco en ne laissant ni aflatoxine B1 résiduelle ni nouveaux dérivés fluorescents. D'autres combinaisons de solvents et d'irradiation ont produit jusqu'à 4 nouveaux dérivés fluorescents de dégradation. L'aflatoxine B1 ne subit pas de dégradation solaire en absence d'humidité. L'acidité augmente la dégradation solaire. Un dérivé fluorescent produit par dégradation solaire de l'aflatoxine B1 dans le chloroforme, s'est dégradé davantage sous l'irradiation solaire dans l'huile de noix de coco mais non dans le chloroforme.

     

A pilot plant for detoxification of aflatoxin B1-contaminated coconut oil by solar irradiation

Summary In coconut oil naturally contaminated with aflatoxin B1, more than 85% of the toxin is present in the soluble form, the remainder occuring in the sediment. This aflatoxin is detoxified when the oil, in a static layer less than 15 mm thick is exposed to solar radiation. A pilot plant, designed to take account of the viscosity and flow characteristics of the oil, was constructed for the exposure of thin layers of oil (2 mm or less) flowing under gravity. At aflatoxin concentrations between 166 and 1250 jug/kg, 75% of the toxin was degraded on exposure to solar radiation of 10 cal/cm²; total detoxification was achieved on repeated exposure. The naturally contaminated coconut oil after exposure to solar radiation did not contain any residual aflatoxins or fluorescent compounds which might have been derived from original aflatoxin B1.

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Resumen Planta pilota para el tratramiento de aceite de coco contaminado con aflatoxina B1 mediante radiation solar y centrifugado En aceite de coco contaminado de forma natural con aflatoxina B1, más del 85% de la toxina se encuentra en forma soluble, el resto permaneciendo en el sedimento. Esta aflatoxina pierde sus propiedades tóxicas cuando se expone el aceite en forma de capa estática de 15 mm de grosor a la radiación solar. Se construyó una planta piloto diseñada teniendo en cuenta la viscosidad y las caracteristicas de fluidez del aceite de forma que pudieran exponerse a la radiación solar capas de aceite muy finas (2 mm o menos) fluyendo gracias a la gravedad. Cuando aceite conteniendo aflatoxina en proporciones entre 166 y 1250 /kg se expuso a una radiación solar de 10 cal./cm² la toxina se degradó en un 75%. La detoxificación total se obtuvo mediante repetición del proceso. El aceite de coco contaminado de forma natural, una vez expuesto a la radiación solar no contenía aflatoxinas residuales ni compuestos fluorescentes potencialmente derivados de la aflatoxina B1 contenida originalmente.

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Résumé Usine-pilote pour la détoxification, par irradiation solaire et centrifugation, de l'huile de coprah contaminée par l'aflatoxine B1 Dans l'huile de coprah spontanément contaminée par l'aflatoxine B1, plus de 85% de la toxine est présente sous forme soluble, le reste se trouvant dans le sédiment. Cette aflatoxine est détoxifiée lorsque l'huile est exposée à la radiation solaire en couche statique de moins de 15 mm d'épaisseur. Une usine-pilote, conçue en tenant compte de la viscosité et de l'écoulement de l'huile, a été construite pour irradier une mince couche d'huile (2 mm ou moins) s'écoulant par gravité. Pour des concentrations en aflatoxine allant de 166 à 1250 g/kg, 75% de la toxine est dégradée par exposition à une irradiation solaire de 10 cal./cm² et, en répétant le traitement, on obtient une détoxification complète. Après exposition à la radiation solaire, l'huile de coprah contaminée spontanément ne contient plus d'aflatoxine résiduelle, ni de composés fluorescents dérivés de l'aflatoxine B1 originelle.

     

Escherichia coli serogroup O107/O117 lipopolysaccharide binds and neutralizes Shiga toxin 2

The AB(5) toxin Shiga toxin 2 (Stx2) has been implicated as a major virulence factor of Escherichia coli O157:H7 and other Shiga toxin-producing E. coli strains in the progression of intestinal disease to more severe systemic complications. Here, we demonstrate that supernatant from a normal E. coli isolate, FI-29, neutralizes the effect of Stx2, but not the related Stx1, on Vero cells. Biochemical characterization of the neutralizing activity identified the lipopolysaccharide (LPS) of FI-29, a serogroup O107/O117 strain, as the toxin-neutralizing component. LPSs from FI-29 as well as from type strains E. coli O107 and E. coli O117 were able bind Stx2 but not Stx1, indicating that the mechanism of toxin neutralization may involve inhibition of the interaction between Stx2 and the Gb(3) receptor on Vero cells.     

Biogeography and genetic diversity of clinical isolates of Burkholderia pseudomallei in Sri Lanka

BackgroundMelioidosis is a potentially fatal infectious disease caused by Burkholderia pseudomallei and the disease is endemic in Southeast Asia and Northern Australia. It has been confirmed as endemic in Sri Lanka. Genomic epidemiology of B. pseudomallei in Sri Lanka is largely unexplored. This study aims to determine the biogeography and genetic diversity of clinical isolates of B. pseudomallei and the phylogenetic and evolutionary relationship of Sri Lankan sequence types (STs) to those found in other endemic regions of Southeast Asia and Oceania.MethodsThe distribution of variably present genetic markers [Burkholderia intracellular motility A (bimA) gene variants bimA_BP/bimA_BM, filamentous hemagglutinin 3 (fhaB3), Yersinia-like fimbrial (YLF) and B. thailandensis-like flagellum and chemotaxis (BTFC) gene clusters and lipopolysaccharide O-antigen type A (LPS type A)] was examined among 310 strains. Multilocus sequence typing (MLST) was done for 84 clinical isolates. The phylogenetic and evolutionary relationship of Sri Lankan STs within Sri Lanka and in relation to those found in other endemic regions of Southeast Asia and Oceania were studied using e BURST, PHYLOViZ and minimum evolutionary analysis.ResultsThe Sri Lankan B. pseudomallei population contained a large proportion of the rare BTFC clade (14.5%) and bimA_BM allele variant (18.5%) with differential geographic distribution. Genotypes fhaB3 and LPSA were found in 80% and 86% respectively. This study reported 43 STs (including 22 novel). e-BURST analysis which include all Sri Lankan STs (71) resulted in four groups, with a large clonal group (group 1) having 46 STs, and 17 singletons. ST1137 was the commonest ST. Several STs were shared with India, Bangladesh and Cambodia.ConclusionThis study demonstrates the usefulness of high-resolution molecular typing to locate isolates within the broad geographical boundaries of B. pseudomallei at a global level and reveals that Sri Lankan isolates are intermediate between Southeast Asia and Oceania.     

Localisation of the Notch family in the human endometrium of fertile and infertile women

To investigate the spatial and temporal immunolocalisation and staining intensity of the Notch signalling family in endometrium of fertile and infertile women, endometrial biopsies were collected by curettage from 25 fertile women across the menstrual cycle and 10 infertile women in the mid secretory phase of menstrual cycle. Immunohisotchemistry was completed for NOTCH1, -2, -3, -4, cleaved Notch, DLL1, -3, -4, JAGGED1, -2, HES and NUMB and immunostaining intensity measured in both the endometrial glandular and luminal epithelium. NOTCH1 and the ligands DLL1 and JAGGED1 were key proteins displaying increased staining intensity during the receptive phase of the menstrual cycle and dysregulated in infertile endometrium. Conversely, NUMB a negative regulator of Notch signalling was decreased in the mid secretory phase of the menstrual cycle in fertile women and increased with infertility.     

Optimizing the microscopic agglutination test (MAT) panel for the diagnosis of Leptospirosis in a low resource,hyper-endemic setting with varied microgeographic variation in reactivity

The microscopic agglutination test (MAT) is the standard serological reference test for the diagnosis of leptospirosis, despite being a technically demanding and laborious procedure. The use of a locally optimised MAT panel is considered essential for proper performance and interpretation of results. This paper describes the procedure of selecting such an optimised panel for Sri Lanka, a country hyper-endemic for leptospirosis. MAT was performed using 24 strains on 1132 serum samples collected from patients presenting with acute undifferentiated fever. Of 24 strains, 15 were selected as the optimised panel, while only 11% of serum samples showed positivity. A geographical variation in predominantly reactive serovars was observed, whereas reactivity was low with the saprophytic strain Patoc. Testing with paired sera yielded a higher sensitivity but provided only a retrospective diagnosis. Serological tests based on ELISA with complementary molecular diagnosis using PCR are a feasible and robust alternative approach to diagnose leptospirosis in countries having a higher burden of the disease.