PubMed Health⌕ Search

Biomedical subjects

S Newton

Publications and source records attributed to S Newton.

10 recordsLinked to original sources
PubMed1990

Lysogenization of Salmonella choleraesuis by phage 14 increases average length of O-antigen chains, serum resistance and intraperitoneal mouse virulence.

Three clones from a strain of Salmonella choleraesuis (serogroup C1) were lysogenized with phage 14 (P14) which converts the O-antigen of serogroup C1 salmonellae from O-6,7 to O-6,7,14. The lysogens were compared with their parental non-lysogenic clones with respect to the following properties: average length of O-antigen polysaccharide chains, sensitivity to normal human serum, and mouse-virulence. SDS-polyacrylamide gel electrophoresis of lipopolysaccharides extracted from these bacteria showed that samples from lysogens consisted mainly of long-chained molecules whereas those from non-lysogens contained mainly short-chained molecules. The O-antigen polysaccharide from a lysogen was estimated by chemical analysis to be six times as long as that from a non-lysogen. Lysogens were serum-resistant whereas non-lysogens were serum-sensitive. About 10 times more colony forming units of a lysogen than of a non-lysogen were recovered from the livers and spleens of mice on day 1 and 3 after intraperitoneal inoculation of equal doses. By comparison with S. choleraesuis, lysogenization of S. typhimurium with phage P22 or phage A4 did not affect the chain-length distribution of O-antigen polysaccharide. Our data suggest that phage 14-coded determinants increase efficiency of O-antigen biosynthesis in S. choleraesuis leading to increase in average length of O-polysaccharide chains. Increased serum resistance and mouse virulence are logical consequences of increase in average length of O-polysaccharide chains and represent phage-conferred selective advantage not previously described in Salmonella.

Animals↗
PubMed1989

Expression of immunogenic epitopes of hepatitis B surface antigen with hybrid flagellin proteins by a vaccine strain of Salmonella.

A nonvirulent Salmonella dublin flagellin-negative, aromatic-dependent live vaccine strain has been used to express hepatitis B virus surface antigen epitopes in an immunogenic form. The envelope proteins of the virion are encoded by the S gene, which contains the pre-S1, pre-S2, and S coding regions. Synthetic oligonucleotides corresponding to amino acid residues S-(122-137) and pre-S2-(120-145) were inserted in-frame into the hypervariable region of a cloned Salmonella flagellin gene, and the recombinant plasmids were introduced into a flagellin-negative aroA mutant live vaccine strain of S. dublin, SL5928. The flagellin gene was expressed in bacteria carrying the plasmids as detected by immunoblotting with anti-flagellin (H1-d) serum. Both the S and pre-S2 epitopes were detected in bacteria carrying the relevant plasmid by immunoblotting with anti-HBs (antibody to hepatitis B virus surface antigen) and anti-peptide antisera. Animals immunized intramuscularly or orally with the live recombinant bacteria developed antibodies specific to these hepatitis B virus epitopes as detected by ELISA.

Amino Acid Sequence↗
PubMed1985

Increased uptake of bone radiopharmaceutical in diabetic neuropathy.

Uptake of radiopharmaceutical was markedly abnormal in all phases of the bone scan in the feet of patients with diabetic neuropathy. Bone scans were performed in three groups of patients; diabetics with neuropathic osteoarthropathy (Charcot joints); diabetics with neuropathy but no evidence of osteoarthropathy and non-diabetic controls. Uptake was monitored in three phases; during the first 2 min after injection, then at 4 min and finally at 4 h. Uptake in all three phases was markedly increased in the neuropathic subjects, not only in those with osteoarthropathy but also in those with no radiological abnormalities. Increased uptake at 2 and 4 min indicates increased blood flow which can also result in increased uptake at 4 h. Increased blood flow secondary to peripheral neuropathy may lead to excessive bone resorption, susceptibility to fracture and finally the development of neuropathic osteoarthropathy of the diabetic foot.

Adult↗