Silica pathogens

B. Fubini and W. E. Wallace, Modulation of silica pathogenicity by surface processes. In Adsorption Silica Surfaces, edited by E. Papirer (M. Dekker, Mulhouse, France, 1999) chap. 20, pp. 645-664. 

Fubini, B. Wallace, W.E. Modulation of Silica Pathogenicity by Surface Processes in Adsorption on Silica Surfaces, E. Papirer, Ed. (Marcel Dekker, Inc. New York, 2000), p. 645. 

Chloroform-methanol extracts of Borrelia burgdorferi were used for the identification of lipids and other related components that could help in the diagnosis of Lyme disease [58]. The provitamin D fraction of skin lipids of rats was purified by PTLC and further analyzed by UV, HPLC, GLC, and GC-MS. MS results indicated that this fraction contained a small amount of cholesterol, lathosterol, and two other unknown sterols in addition to 7-dehydrocholesterol [12]. Two fluorescent lipids extracted from bovine brain white matter were isolated by two-step PTLC using silica gel G plates [59]. PTLC has been used for the separation of sterols, free fatty acids, triacylglycerols, and sterol esters in lipids extracted from the pathogenic fungus Fusarium culmorum [60]. 

Figure 10.5 Plant cell cultures have proven to be very useful for studying plant-pathogen interactions and isoprenoid metabolism. Tobacco cell cultures respond rapidly to the addition of fungal elicitors (0.5 pg cellulase/ml of culture) by browning (A) (analogous to a hypersensitive response) and the production of phytoalexins (B). Media was collected from elicited cell cultures at the indicated times, partitioned against an organic solvent, and concentrated aliquots run on a silica TLC plate. The plates were then sprayed with a suspension of Cladosporium cucumerinum spores and incubated in a humid environment for 5 days before viewing (B). The compound released from the elicitor-treated tobacco cells that inhibits spore germination is capsidiol, a sesquiterpene.

In addition. Yuan and coworkers described spherical silica-based luminescent europium nanoparticles with a uniform size of about 10 nm in diameter [87]. Interestingly, the nanoparticles can be excited over a wavelength range from the UV to visible light (200 50 nm) in aqueous solution, and could be used for time-resolved luminescence imaging of an environmental pathogen, Giardia lamblia. 

Bums A, Ow H, Wiesner U. Huorescent core-shell silica nanoparticles towards Lab on a Particle architectures for nanobiotechnology. Chem. Soc. Rev. 2006 35 1028-1042. Hindson BJ, Makarewicz AJ, Setlur US, Henderer BD, McBride MT, Dzenitis JM. APDS the autonomous pathogen detection system. Biosensors Bioelectron. 2005 20 1925-1931. 

Although resistance of Magnolia spp. to pests is not a topic of this review, the report of the presence of silica in the leaves of M. grandiflora is interesting. It is hypothesized that presence of silica in the leaves may increase the plant s resistance to pathogens, as well as strengthening the leaf and reducing transpiration [87]. 

The tetrahedral - and thus pathogenic - crystalline phases of silica are as follows ... 

He concluded that the solubility theory was not applicable. Instead the chemical properties of the surface of the silica particle directly involved them in reaction with tissues. Physical theories were generally judged inadequate. Although there may be some correlation between specific surface area, or adsorption, capacity for albumin and pathogenicity, exceptions can generally be found. An explanation of how a silica particle kills a phagocyte is far from an explanation of the biochemical interactions involved in the development of a silicotic lesion. 

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