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- Elversson, J, et al.
(författare)
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Droplet and particle size relationship and shell thickness of inhalable lactose particles during spray drying
- 2003
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Ingår i: Journal of Pharmaceutical Sciences. - : Wiley. - 0022-3549 .- 1520-6017. ; 92, s. 900-910
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Tidskriftsartikel (refereegranskat)abstract
- To find means of controlling the size and density of particles intended for inhalation the relationship between droplet and particle size during spray drying was investigated. Lactose solutions were atomized with a two-fluid nozzle and dried in a laboratory spray drier. The effects of nozzle orifice diameter, atomization airflow and feed concentration on droplet and particle size were examined. Mass median diameter of both droplets and particles were analyzed with laser diffraction. In addition, scanning electron microscopy and transmission electron microscopy were used for studies of particle shape and morphology. It was demonstrated that nozzle orifice diameter and airflow, but not feed concentration controlled the droplet size during atomization. Increasing droplet size increased particle size but the effect was also influenced by feed concentration. Particles from solutions of a low concentration (1% w/w) were smaller than those from higher concentrations (5-20% w/w). This may be partly explained by lower yields at higher feed concentrations, but may also be related to differences in drying rate. Spray-dried lactose solutions formed hollow particles, and it was suggested that the shell thickness of the particles increased with increasing feed concentration
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| 5. |
- Kauppi, Anna, 1971-, et al.
(författare)
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Targeting bacterial Virulence : Inhibitors of type III secretion in Yersinia
- 2003
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Ingår i: Chemistry and Biology. - 1074-5521 .- 1879-1301. ; 10:3, s. 241-249
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Tidskriftsartikel (refereegranskat)abstract
- Agents that target bacterial virulence without detrimental effect on bacterial growth are useful chemical probes for studies of virulence and potential candidates for drug development. Several gram-negative pathogens employ type III secretion to evade the innate immune response of the host. Screening of a chemical library with a luciferase reporter gene assay in viable Yersinia pseudotuberculosis furnished several compounds that inhibit the reporter gene signal expressed from the yopE promoter and effector protein secretion at concentrations with no or modest effect on bacterial growth. The selectivity patterns observed for inhibition of various reporter gene strains indicate that the compounds target the type III secretion machinery at different levels. Identification of this set of inhibitors illustrates the approach of utilizing cell-based assays to identify compounds that affect complex bacterial virulence systems.
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| 6. |
- Millqvist-Fureby, Anna, et al.
(författare)
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Surface composition of spray-dried milk protein-stabilised emulsions in relation to pre-heat treatment of proteins
- 2001
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Ingår i: Colloids and Surfaces B. - 0927-7765 .- 1873-4367. ; 21, s. 47-58
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Tidskriftsartikel (refereegranskat)abstract
- Several important technical properties of spray-dried food powders depend on particle-liquid interactions (e.g. wettability, dispersability) and particle-particle interactions (e.g. flowability). It can be assumed that the chemical composition of the surface layer of the particles to a large extent determine these properties. The present study has been aimed to investigate the relation between the surface composition of spray-dried milk protein-stabilised emulsions and pre-heat treatment of the proteins. Solutions of WPC were heat-treated at low (60-90°C) and high (140°C) temperature and the degree of denaturation was determined, prior to the preparation of emulsions with rapeseed oil. The surface composition of the dry powders were established by using ESCA (electron spectroscopy of chemical analysis).The emulsions were characterised by droplet size distribution before spray drying and after dissolution of the powders. Also free fat extractions and estimations of wettability (dissolution rates) were performed. The powder surface coverage of protein decreased with increasing degree of protein denaturation before the emulsification, whereas the emulsion droplet size increased both before spray drying and after reconstitution of powders. The free fat extraction as well as the dissolution rate, whereof the latter decreased with increasing surface fat coverage, correlated well with the fat coverage of the powder surface.
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