A two-dimensional electrophoretic study of serum amyloid A and C-reactive protein in infants and children.

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was used to analyze C-reactive - (CRP) and serum amyloid A protein (SAA) in infants and children. Five SAA isotypes were identified. CRP showed vertical streaking, and its optical density values correlated with immunoturbidimetric measurements. As evaluated by densitometry, both proteins showed an age-dependent variation. In more than 50% of the neonates, SAA was present in equal or higher amounts than CRP, and only SAA1alpha could be detected. In children, CRP was expressed in higher amounts than SAA, and both SAA1alpha and SAA2alpha were present. N-terminally modified forms of both isotypes were present regardless of age, including in premature infants. These results suggest that the overall synthesis of the gene products SAA1alpha and SAA2alpha is developmentally regulated, but at the same time that their N-terminal processing occurs independently of developmental factors. The presented data suggest that SAA has an important function in neonates, and that the role of SAA as an infection marker in this population should be investigated further.

Isolation of serum amyloid A protein by small-scale hydrophobic interaction chromatography and two-dimensional electrophoresis.

A recently introduced technique to isolate serum amyloid A protein is hydrophobic interaction chromatography combined with two-dimensional electrophoresis with immobilized pH gradients. A modification of the original version of this technique is presented. Mouse serum was subjected to hydrophobic interaction chromatography on a small scale, and the eluate was applied directly to two-dimensional electrophoresis. Simple electropherogramss with optimal resolution of serum amyloid A protein were obtained. The presented technique facilitates isolation of serum amyloid A protein from small blood volumes, and might also be adapted to alternative applications.

Characterization of human serum amyloid A protein isoforms separated by two-dimensional electrophoresis by liquid chromatography/electrospray ionization tandem mass spectrometry.

A detailed structural analysis of the serum amyloid A proteins (SAA) of an individual with highly active, chronic rheumatoid arthritis is reported. SAA isoforms were separated by high-resolution two dimensional (2-D) gel electrophoresis. Peptide mapping by reverse-phase chromatography/electrospray ionization tandem mass spectrometry was applied to correlate the protein(s) contained in each spot with their respective coding gene and to study the post-translational processing and modification events which might result in differential electrophoretic mobility. Nine protein spots were analyzed. The six major spots corresponded to the Arg and des-Arg forms of SAA1 alpha and SAA2 alpha, respectively, and to the glycosylated and nonglycosylated form of constitutive serum amyloid A protein (C-SAA). Two minor spots were identified as SAA1 alpha isoforms containing post-translational modifications. We suggest that these variants contained a gamma-N, N'-dimethylasparagine residue at position 83 and that one of them was additionally oxidized at Trp53 and Trp85. The ninth spot was shown to contain a mixture of SAA1 alpha and SAA2 alpha. To our knowledge, this is the first report in which analysis of peptides has been used to verify the presence of C-SAA in acute-phase serum. Furthermore, the data illustrate that extensive post-translational processing results in a structurally diverse class of acute-phase SAA proteins, which are derived from a small number of genes. Finally, the fast and conclusive technology used in this study promises to be generally useful for the comprehensive investigation of proteins at the level of the primary structure.

Serum amyloid A protein in humans and four animal species: a comparison by two dimensional electrophoresis.

Two-dimensional electrophoresis and N-terminal analysis were used to study serum amyloid A protein (SAA) from humans, mink, fox, goat and rabbit. Previously uncharacterized SAA variants were demonstrated in fox, goat and rabbit, and considerable interspecies homology was seen. In rabbit, two novel SAAs were characterized, and SAA1 and SAA2 were demonstrated in mink and rabbit sera. The results confirm previous cDNA studies and indicate that SAA do possess an important function also in fox and goat.

Characterization and quantification of mink serum amyloid A protein using two-dimensional electrophoresis with immobilized pH gradients.

Using hydrophobic interaction chromatography, two-dimensional electrophoresis with an immobilized pH gradient in the first dimension and semidry blotting, three isoforms of mink serum amyloid A protein (SAA) were characterized and studied during chronic inflammation. Compared to conventional methods that have been applied to SAA, the major advantages of the present combination of methods are: (i) use of small serum volumes, (ii) rapid extraction, (iii) high resolution, and (iv) high yield of proteins.

Rat bite fever (Streptobacillus moniliformis) with septicemia in a child.

A 5-year-old girl was admitted to hospital with fever, headache and nausea. Her C-reactive protein raised from less than 11 mg/l to 65 mg/l and she developed a maculopapular, petechial rash, especially pronounced on the soles and palms. After incubation for 3 days, Streptobacillus moniliformis was found in all blood cultures that had been taken. Some weeks before her admission, the girl had been playing with her grandmother's pet rats, which later had died from an unknown disease. There was no history of rat bite. Her condition improved rapidly after treatment with penicillin and chloramphenicol, and she was discharged from hospital after 10 days without sequelae.