Fluorescence Single Particle Tracking for the Characterization of Submicron Protein Aggregates in Biological Fluids and Complex Formulations

To evaluate the potential of fluorescence single particle tracking (fSPT) for the characterization of submicron protein aggregates in human serum, plasma and formulations containing human serum albumin (HSA). A monoclonal IgG was covalently labeled with a fluorescent dye and cross-linked with glutaraldehyde. IgG aggregates and fluorescent beads of 0.1 mu m (control) were diluted in buffer, serum and plasma, and their size distributions were analyzed by fSPT and nanoparticle tracking analysis (NTA). In a separate experiment, IgG and HSA, fluorescently labeled with different dyes, were mixed and subjected to heat stress. The stressed sample was analyzed by fSPT using a dual color mode and by NTA. The accuracy and precision of fSPT proved to be comparable to NTA. fSPT was able to successfully measure all the samples in buffer, serum and plasma. The average size of the cross-linked protein aggregates showed a slight increase in biological fluids. Moreover, fSPT analysis showed that a significant proportion of the aggregates formed by subjecting an IgG/HSA mixture to heat stress were composed of both proteins. fSPT is a powerful technique for the characterization of submicron protein aggregates in biological fluids and complex formulations

Het belang van Norovirus detectie bij collectieve gastro-enteritis uitbraken: van diagnose tot desinfectie van de besmettingshaard

Tijdens de maanden juli en augustus van 2010 kregen een aantal jeugdbewegingen in Vlaanderen te kampen met een Norovirus-infectie tijdens hun jaarlijkse zomerkamp. Hierbij werden minstens 180 personen ziek en 55 personen gehospitaliseerd. Onderzoek van de omgeving toonde aan dat voornamelijk gemeenschappelijke plaatsen zoals de sanitaire ruimten besmet waren met Norovirus en waarschijnlijk een belangrijke verspreidingshaard vormden voor Norovirus. Een snelle diagnose met daaropvolgend een adequate reiniging en desinfectie van de omgeving is belangrijk om secundaire Norovirusuitbraken te voorkomen.</p

Shigellosis outbreak linked to canteen-food consumption in a public institution: a matched case-control study36545

On 13 November 2009, the authorities of Flemish Brabant, Belgium, received an alert concerning a potential outbreak of Shigella sonnei at a public institution. A study was conducted to assess the extent, discover the source and to implement further measures. We performed a matched case-control study to test an association between shigellosis and canteen-food consumption. Water samples and food handlers&#039; faecal samples were tested. The reference laboratory characterized the retrospectively collected Shigella specimens. We found 52 cases distributed over space (25/35 departments) and time (2 months). We found a matched odds ratio of 3.84 (95% confidence interval 1.02-14.44) for canteen-food consumption. A food handler had travelled to Morocco shortly before detection of the first laboratory-confirmed case. Water samples and food handlers&#039; faecal samples tested negative for Shigella. Confirmed cases presented PFGE profiles, highly similar to archived isolates from Morocco. Foodborne transmission associated with the canteen was strongly suspected</p

Measuring the intravitreal mobility of nanomedicines with singe-particle tracking microscopy

Aim:\ud To develop a robust assay to evaluate and compare the intravitreal mobility of nanoparticles in the intact vitreous body.\ud \ud Materials & methods:\ud Excised bovine eyes were prepared to preserve the fragile structure of the vitreous humor, while permitting high-resolution fluorescence microscopy and single-particle tracking analysis of intravitreally injected nanoparticles. This assay was validated by analyzing polystyrene beads and further employed to evaluate gene nanomedicines composed of poly(amido amine)s and plasmid DNA. \ud \ud Results:\ud The assay was able to distinguish immobilized cationic nanoparticles from mobile PEGylated nanoparticles. PEGylation of the polyplexes resulted in a drastic improvement of their mobility.\ud \ud Conclusion:\ud An ex vivo eye model is presented for studying nanoparticle mobility in intact vitreous humor by single-particle tracking microscopy. These results give important guidelines for developing gene- and drug-delivery nanomedicines that are compatible with intravitreal administration

Lessons learned from a textbook outbreak: EHEC-O157:H7 infections associated with the consumption of raw meat products, June 2012, Limburg, Belgium.

&lt;p&gt;&lt;b&gt;BACKGROUND: &lt;/b&gt;On 5 June 2012 several enterohemorrhagic Escherichia coli, EHEC, O157:H7 infections were reported to the public health authorities of Limburg.&lt;/p&gt;&lt;p&gt;&lt;b&gt;METHODS: &lt;/b&gt;We performed a case-control study, a trace back/forward investigation and compared strains isolated from human cases and food samples. A case was defined as anyone with a laboratory-confirmed E. coli O157:H7-infection in North-East Limburg from May 30 2012 till July 15 2012. Family members with bloody diarrhea were also included as cases. E. coli O157 was isolated by culture and the presence of the virulence genes was verified using (q)PCR. Isolates were genotyped and compared by Pulsed Field Gel Electrophoresis (PFGE) and insertion sequence 629-printing (IS629-printing).&lt;/p&gt;&lt;p&gt;&lt;b&gt;RESULTS: &lt;/b&gt;The outbreak involved 24 cases, of which 17 were laboratory-confirmed. Five cases developed Hemolytic Uremic Syndrome (HUS) and fifteen were hospitalized. Cases reported a significantly higher consumption of &quot;steak tartare&quot;, a raw meat product (OR 48.12; 95% CI; 5.62- 416.01). Cases were also more likely to buy meat-products at certain butcheries (OR 11.67; 95% CI; 1.41 - 96.49). PFGE and IS629-printing demonstrated that the vtx1a vtx2a eae ehxA positive EHEC O157:H7 strains isolated from three meat products and all seventeen human stool samples were identical. In a slaughterhouse, identified by the trace-back investigation, a carcass infected with a different EHEC strain was found and confiscated.&lt;/p&gt;&lt;p&gt;&lt;b&gt;CONCLUSION: &lt;/b&gt;We present a well described and effectively investigated foodborne outbreak associated with meat products. Our main recommendations are the facilitation and acceleration of the outbreak detection and the development of a communication plan to reaches all persons at risk.&lt;/p&gt;&lt;p&gt;&lt;b&gt;MESH: &lt;/b&gt;Foodborne diseases, Shiga-toxigenic Escherichia coli, Enterohemorrhagic Escherichia coli, Meat products, Case control studies, Electrophoresis, Gel, Pulsed-Field.&lt;/p&gt;</p