Rapid separation of living cells by colloidal silica density gradient centrifugation

1977 ◽  
Vol 3 (4) ◽  
pp. 717-719 ◽  
Author(s):  
David A. Wolff
Keyword(s):  
Density Gradient ◽  
Colloidal Silica ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Living Cells ◽  
Rapid Separation

scholarly journals Rapid Separation of LDL Subclasses by Iodixanol Gradient Ultracentrifugation

2003 ◽  
Vol 49 (11) ◽  
pp. 1865-1872 ◽  
Author(s):  
Ian G Davies ◽  
John M Graham ◽  
Bruce A Griffin
Keyword(s):  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Digital Photography ◽  
Rapid Separation ◽  
Simple Method ◽  
Peak Density ◽  
Plasma Triglycerides ◽  
Threefold Increase ◽  
Chd Risk

Abstract Background: A predominance of small, dense LDL (sdLDL) confers in excess of a threefold increase in coronary heart disease (CHD) risk. The conventional method for the detection of sdLDL, salt density gradient ultracentrifugation (DGUC) has been superseded by more rapid techniques. This report presents novel methodology for the separation of sdLDL by a combination of iodixanol density gradient centrifugation and digital photography. Methods: LDL subclasses were separated in 3 h from prestained plasma on a self-forming density gradient of iodixanol. LDL subclass profiles were generated by digital photography and gel-scan software. Plasma samples from 106 normo- and dyslipidemic individuals were used to optimize the gradient for the resolution of LDL heterogeneity. A subgroup of 47 LDL profiles were then compared with LDL subclasses separated by salt DGUC. Results: The peak density of the predominant LDL band correlated significantly with the relative abundance (as a percentage) of sdLDL as resolved by salt DGUC (P <0.001). As shown previously, LDL isolated at a lighter density in iodixanol compared with salt gradients. A predominance of sdLDL corresponded to a peak density on iodixanol of 1.028 kg/L. This density and the area under the LDL profile lying above this density were sensitive and specific markers for the prediction of a predominance of sdLDL (P <0.001) and showed predictable associations with plasma triglycerides (r = 0.59; P <0.001) and HDL (r = −0.4; P <0.001). Conclusions: This simple method for the detection of sdLDL can differentiate a predominance of sdLDL, is highly reproducible, and can be used preparatively to isolate sdLDL.

scholarly journals Rapid Separation and Concentration of Food-Borne Pathogens in Food Samples Prior to Quantification by Viable-Cell Counting and Real-Time PCR

2006 ◽  
Vol 73 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Hiroshi Fukushima ◽  
Kazunori Katsube ◽  
Yukiko Hata ◽  
Ryoko Kishi ◽  
Satomi Fujiwara
Keyword(s):  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Viable Cell ◽  
Food Samples ◽  
Cell Counting ◽  
Rapid Separation ◽  
Food Borne Pathogens ◽  
Food Borne

ABSTRACT Buoyant density gradient centrifugation has been used to separate bacteria from complex food matrices, as well as to remove compounds that inhibit rapid detection methods, such as PCR, and to prevent false-positive results due to DNA originating from dead cells. Applying a principle of buoyant density gradient centrifugation, we developed a method for rapid separation and concentration following filtration and low- and high-speed centrifugation, as well as flotation and sedimentation buoyant density centrifugation, for 12 food-borne pathogens (Salmonella enterica, Escherichia coli, Yersinia enterocolitica, Campylobacter jejuni, Vibrio cholerae O139, Vibrio parahaemolyticus O3K6, Vibrio vulnificus, Providencia alcalifaciens, Aeromonas hydrophila, Bacillus cereus, Staphylococcus aureus, and Clostridium perfringens) in 13 different food homogenates. This method can be used prior to real-time quantitative PCR (RTi-qPCR) and viable-cell counting. Using this combined method, the target organisms in the food samples theoretically could be concentrated 250-fold and detected at cell concentrations as low as 101 to 103 CFU/g using the RTi-qPCR assay, and amounts as small as 100 to 101 CFU/g could be isolated using plate counting. The combined separation and concentration methods and RTi-qPCR confirmed within 3 h the presence of 101 to 102 CFU/g of Salmonella and C. jejuni directly in naturally contaminated chicken and the presence of S. aureus directly in remaining food items in a poisoning outbreak. These results illustrated the feasibility of using these assays for rapid inspection of bacterial food contamination during a real-world outbreak.

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