ABSTRACT Activated platelets play a pivotal role in cardiovascular diseases such as atherothrombo... more ABSTRACT Activated platelets play a pivotal role in cardiovascular diseases such as atherothrombosis. Therefore, strategies enabling activated platelet molecular imaging are of great interest. Herein, a chemical protocol was investigated for coating superparamagnetic iron oxide nanoparticles with low molecular weight fucoidan, a ligand of P-selectin expressed on the surface of activated platelets. The physico-chemical characterization of the obtained product demonstrated successful fucoidan coating and its potential as a T2 MRI contrast agent. The specificity and the strength of the interaction between fucoidan-coated iron oxide nanoparticles and human activated platelets was demonstrated by flow cytometry. Micromagnetophoresis experiments revealed that platelets experience magnetically-induced motion in the presence of a magnetic field gradient created by a micromagnet. Altogether, these results indicate that superparamagnetic iron oxide nanoparticles coated with low molecular weight fucoidan may represent a promising molecular imaging tool for activated platelets in human diseases.
Fucoidans constitute a large family of sulfated polysaccharides with several biochemical properti... more Fucoidans constitute a large family of sulfated polysaccharides with several biochemical properties. A commercial fucoidan from brown algae, containing low molecular weight polysaccharidic species constituted of l-fucose, uronic acids and sulfate groups, was simply treated here with calcium acetate solution. This treatment led to a purified fraction with a yield of 45%. The physicochemical characterizations of the purified fucoidan using colorimetric assay, MALLS, dRI, FT-IR, NMR, exhibited molecular weight distributions and chemical profiles similar for both fucoidans whereas the sulfate and l-fucose contents increased by 16% and 71%, respectively. The biodistribution study in rat of both compounds labeled with 99mTc evidenced a predominant renal elimination of the purified fucoidan, but the crude fucoidan was mainly retained in liver and spleen. In rat myocardial ischemia-reperfusion, we then demonstrated the better efficiency of the purified fucoidan. This purified sulfated polysaccharide appears promising for the development of molecular imaging in acute coronary syndrome.
A study was carried out to estimate the proportion of diseases due to milk and milk products amon... more A study was carried out to estimate the proportion of diseases due to milk and milk products among food-borne diseases recorded in France and in other countries since 1980. Particular attention was given to whether the milk involved was heat-treated or not. Four etiologic agents were considered: Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, and pathogenic Escherichia coli. An overview of food-borne disease annual reports from seven countries indicated that milk and milk products were implicated in 1-5% of the total bacterial outbreaks; however, details about the type of product and milk involved were usually not provided. When considering 60 outbreaks and four single cases described in the literature and implicating milk and milk products, confirmed or suspected food vehicles were distributed as follows: milk, 39.1%, cheese, 53.1%, other milk products, 7.8%. Overall, 32.8% of the food vehicles were made from pasteurised milk; 37.5% from raw milk; 10.9% from milk stated as "unpasteurised"; and 18.8% from unspecified milk. Salmonella spp. were responsible for 29 outbreaks, L. monocytogenes for 10 outbreaks and four well-documented single cases, pathogenic E. coli for 11 outbreaks, and S. aureus for 10 outbreaks. Analysis of unpublished data about food-borne disease outbreaks, listeriosis excluded, collected by the coordinator of the French surveillance system from 1992 to 1997, revealed 69 documented outbreaks for which milk and milk products were confirmed as the vehicle by the isolation of the etiologic agent. The food vehicles were distributed as follows: milk, 10%; cheese, 87%; others, 3%. UHT milk accounted for 1.5%, raw milk and raw milk products for 48%, and milk and milk products from unspecified milk for 50.5% of the 69 outbreaks. S. aureus was by far the most frequent pathogen associated with these outbreaks (85.5% of the outbreaks), followed by Salmonella (10.1%). This study demonstrates the limitations of the surveillance systems and the difficulties in estimating the contribution of milk and milk products to food-borne diseases. In particular, it was not possible to find out in many outbreaks what heat treatment, if any, the milk had undergone.
Baird-Parker (BP) medium is the selective medium most commonly used to enumerate coagulase-positi... more Baird-Parker (BP) medium is the selective medium most commonly used to enumerate coagulase-positive staphylococci in food. However, it seems often not sufficiently selective for the analysis of raw foodstuffs which present a high level of concomitant flora. An alternative medium, rabbit plasma fibrinogen agar (RPFA) medium, is now available but has not yet been tested extensively with cheeses made from raw milk. Therefore, a comparison of both media was carried out with 77 samples from four types of raw-milk cheeses. Two brands of RPFA medium were compared with one brand of BP medium. This last medium was tested after two different shelf lives at +4°C, 1 day and 4 months, to evaluate the possible influence of the storage delay on its stability. Enumeration results from 20 (26%) of the 77 samples could not be used for statistical analysis because of reading problems observed on one or several of the media. These problems, due to a high level of concomitant flora, were more frequently observed using BP medium (18 samples) than using RPFA media (two to three samples). Enumeration means obtained for the 57 (74%) samples retained for statistical purposes were not significantly different between the two types of medium. This study shows that BP medium can be used after a storage delay at +4°C of 4 months as ready-to-use commercialized medium. However, as RPFA media are much easier and faster to read than BP medium, and as they give similar or even more precise enumeration results than BP medium, the use of RPFA media is recommended to enumerate coagulase-positive staphylococci in cheeses made from raw milk.
ABSTRACT Activated platelets play a pivotal role in cardiovascular diseases such as atherothrombo... more ABSTRACT Activated platelets play a pivotal role in cardiovascular diseases such as atherothrombosis. Therefore, strategies enabling activated platelet molecular imaging are of great interest. Herein, a chemical protocol was investigated for coating superparamagnetic iron oxide nanoparticles with low molecular weight fucoidan, a ligand of P-selectin expressed on the surface of activated platelets. The physico-chemical characterization of the obtained product demonstrated successful fucoidan coating and its potential as a T2 MRI contrast agent. The specificity and the strength of the interaction between fucoidan-coated iron oxide nanoparticles and human activated platelets was demonstrated by flow cytometry. Micromagnetophoresis experiments revealed that platelets experience magnetically-induced motion in the presence of a magnetic field gradient created by a micromagnet. Altogether, these results indicate that superparamagnetic iron oxide nanoparticles coated with low molecular weight fucoidan may represent a promising molecular imaging tool for activated platelets in human diseases.
Fucoidans constitute a large family of sulfated polysaccharides with several biochemical properti... more Fucoidans constitute a large family of sulfated polysaccharides with several biochemical properties. A commercial fucoidan from brown algae, containing low molecular weight polysaccharidic species constituted of l-fucose, uronic acids and sulfate groups, was simply treated here with calcium acetate solution. This treatment led to a purified fraction with a yield of 45%. The physicochemical characterizations of the purified fucoidan using colorimetric assay, MALLS, dRI, FT-IR, NMR, exhibited molecular weight distributions and chemical profiles similar for both fucoidans whereas the sulfate and l-fucose contents increased by 16% and 71%, respectively. The biodistribution study in rat of both compounds labeled with 99mTc evidenced a predominant renal elimination of the purified fucoidan, but the crude fucoidan was mainly retained in liver and spleen. In rat myocardial ischemia-reperfusion, we then demonstrated the better efficiency of the purified fucoidan. This purified sulfated polysaccharide appears promising for the development of molecular imaging in acute coronary syndrome.
A study was carried out to estimate the proportion of diseases due to milk and milk products amon... more A study was carried out to estimate the proportion of diseases due to milk and milk products among food-borne diseases recorded in France and in other countries since 1980. Particular attention was given to whether the milk involved was heat-treated or not. Four etiologic agents were considered: Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, and pathogenic Escherichia coli. An overview of food-borne disease annual reports from seven countries indicated that milk and milk products were implicated in 1-5% of the total bacterial outbreaks; however, details about the type of product and milk involved were usually not provided. When considering 60 outbreaks and four single cases described in the literature and implicating milk and milk products, confirmed or suspected food vehicles were distributed as follows: milk, 39.1%, cheese, 53.1%, other milk products, 7.8%. Overall, 32.8% of the food vehicles were made from pasteurised milk; 37.5% from raw milk; 10.9% from milk stated as "unpasteurised"; and 18.8% from unspecified milk. Salmonella spp. were responsible for 29 outbreaks, L. monocytogenes for 10 outbreaks and four well-documented single cases, pathogenic E. coli for 11 outbreaks, and S. aureus for 10 outbreaks. Analysis of unpublished data about food-borne disease outbreaks, listeriosis excluded, collected by the coordinator of the French surveillance system from 1992 to 1997, revealed 69 documented outbreaks for which milk and milk products were confirmed as the vehicle by the isolation of the etiologic agent. The food vehicles were distributed as follows: milk, 10%; cheese, 87%; others, 3%. UHT milk accounted for 1.5%, raw milk and raw milk products for 48%, and milk and milk products from unspecified milk for 50.5% of the 69 outbreaks. S. aureus was by far the most frequent pathogen associated with these outbreaks (85.5% of the outbreaks), followed by Salmonella (10.1%). This study demonstrates the limitations of the surveillance systems and the difficulties in estimating the contribution of milk and milk products to food-borne diseases. In particular, it was not possible to find out in many outbreaks what heat treatment, if any, the milk had undergone.
Baird-Parker (BP) medium is the selective medium most commonly used to enumerate coagulase-positi... more Baird-Parker (BP) medium is the selective medium most commonly used to enumerate coagulase-positive staphylococci in food. However, it seems often not sufficiently selective for the analysis of raw foodstuffs which present a high level of concomitant flora. An alternative medium, rabbit plasma fibrinogen agar (RPFA) medium, is now available but has not yet been tested extensively with cheeses made from raw milk. Therefore, a comparison of both media was carried out with 77 samples from four types of raw-milk cheeses. Two brands of RPFA medium were compared with one brand of BP medium. This last medium was tested after two different shelf lives at +4°C, 1 day and 4 months, to evaluate the possible influence of the storage delay on its stability. Enumeration results from 20 (26%) of the 77 samples could not be used for statistical analysis because of reading problems observed on one or several of the media. These problems, due to a high level of concomitant flora, were more frequently observed using BP medium (18 samples) than using RPFA media (two to three samples). Enumeration means obtained for the 57 (74%) samples retained for statistical purposes were not significantly different between the two types of medium. This study shows that BP medium can be used after a storage delay at +4°C of 4 months as ready-to-use commercialized medium. However, as RPFA media are much easier and faster to read than BP medium, and as they give similar or even more precise enumeration results than BP medium, the use of RPFA media is recommended to enumerate coagulase-positive staphylococci in cheeses made from raw milk.
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