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Biomedical subjects

R Christian

Publications and source records attributed to R Christian.

50 records · Page 3Linked to original sources
PubMed1985

Synthesis of alternate linear and branched repeating units of the Escherichia coli LP 1092 capsular polysaccharide containing 3-deoxy-alpha-D-manno-2-octulosonic acid (KDO) linked to secondary positions of D-ribose.

The oligosaccharides, methyl 3-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-beta-D-ribofuranosid e, methyl 2-O-beta-D-ribofuranosyl-3-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-beta-D-ribofuranosid e, and methyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----2)-O-beta-D- ribofuranosyl-(1----2)-beta-D-ribofuranoside were prepared in high purity and good over-all yields. The constitutions of the trisaccharide derivatives correspond to the repeating units of the proposed linear and branched structures of the capsular polysaccharide(s) from Escherichia coli LP 1092. The alpha-KDO-(2----3)-beta-D-Ribf and alpha-KDO-(2----2)-beta-D-Ribf units were synthesized by a modification of the Helferich procedure using methyl (4,5,7,8-tetra-O-acetyl-3-deoxy-alpha-D-manno-2-octulopyranosyl bromide)-onate and appropriate beta-D-ribofuranosyl derivatives. The constitutional and configurational assignments were based on the 250-MHz 1H-n.m.r.-spectra of protected derivatives of the oligosaccharides.

Carbohydrate Conformation↗
PubMed1985

Empirical 13C-n.m.r.-correlations between the Escherichia coli K 13 and LP 1092 capsular polysaccharides and model oligosaccharides containing D-ribose and 3-deoxy-D-manno-2-octulosonic acid.

The proton-decoupled, Fourier-transform, 13C-n.m.r. spectra of the two anomeric sodium (methyl 3-deoxy-7-O-beta-D-ribofuranosyl-alpha- and beta-D-manno-2-octulopyranosid)onates, of the two anomeric sodium [methyl 3-deoxy-7-O-(2-O-beta-D-ribofuranosyl-beta-D-ribofuranosyl)-alpha- or -beta-D-manno-2-octulopyranosid]onates, and of methyl 2-O-beta-D-ribofuranosyl-beta-D-ribofuranoside have been recorded. The constitutions of these compounds correspond to repeating units and partial structures of the capsular polysaccharides from Escherichia coli K 13, K 20, K 23, and LP 1092 strains. The 13C-n.m.r.-line patterns of these oligosaccharide derivatives and the corresponding polysaccharides show striking differences dependent upon the anomeric configurations of the KDO residues. These differences may be used for the identification, by visual or computer-assisted pattern analysis, of the anomeric configurations of KDO-residues in oligo- or poly-saccharides. Thus, it was confirmed that the KDO residues in the K 13, K 20, and K 23 polysaccharides have the beta anomeric configuration, whereas those in the LP 1092 polysaccharide have the alpha anomeric configuration.

Carbohydrate Conformation↗
PubMed1985

Megestrol acetate v tamoxifen in advanced breast cancer: a phase III trial of the Piedmont Oncology Association (POA).

One hundred twenty-four patients with recurrent or metastatic breast cancer were randomized to receive megestrol acetate 40 mg orally, four times daily, or tamoxifen 10 mg orally twice daily. If therapy failed patients were crossed over to the alternate treatment. Eligibility required that either the estrogen or progesterone receptor be positive or that both values be unknown, and that patients be at least 2 years postspontaneous menopause or over 50 years of age. Pretreatment characteristics were similar for both groups. Three patients had had previous hormonal therapy while one third had had chemotherapy. Objective response for evaluable patients based on strict UICC criteria was 29% with megestrol acetate and 31% with tamoxifen. Responses in patients with bone and soft tissue disease were similar for both regimens; however, 7 of 19 (37%) patients with visceral disease responded to tamoxifen but none of 18 (0%) responded to megestrol acetate. Response did not correlate with amount of estrogen or progesterone receptor. Unadjusted analysis of time to progression and survival showed no significant differences between regimens. With adjustment for pretreatment characteristics, patients on tamoxifen had a statistically significant prolongation of both of these parameters. Crossover data show 3 of 24 patients responding to tamoxifen after failure on megestrol acetate and 1 of 24 responding to megestrol acetate after failure on tamoxifen. However, crossover data should be viewed cautiously, as patients who are currently responding to initial treatment are those who would be most likely to respond to crossover therapy.

Aged↗
PubMed1984

Effect of particle size of dried mycobacteria on adjuvant induced arthritis in the rat.

Freund's complete adjuvant prepared by grinding dried, heat killed Mycobacterium tuberculosis with liquid paraffin was investigated for particle size-weight distribution. Variations in the grinding times and preparative procedure had a marked effect on the arthritogenic action of the adjuvant in the rat. A satisfactory response in the injected foot was found only when the particle size was less than 19 microns and a secondary response in the non-injected foot required particles less than 10 microns in diameter.

Animals↗
PubMed1975

The effects of high and low erucic acid rapeseed oils in diets for rats.

Fully refined rapessed oils of high (regular rapeseed oil, B. campestris) and low erucic acid content (Span oil, B. campestris; commercially hydrogenated Span oil and Zephyr oil, B. napus) and soybean oil were fed to male and female Sprague-Dawley rats at a level of 15% by weight in the diet. In the first experiment, 5 male and 5 female rats per treatment were housed individually, whereas in the second experiment 5 male or 5 female rats per treatment were housed in groups of five. Body weight gain was not influenced by the dietary treatments in experiment 1. However, in experiment 2 the groups fed the diets containing regular rapeseed oil or Span oil showed significantly (P less than 0.05) lower body weight gains when compared to soybean oil fed groups but not when compared to the hydrogenated Span or Zephyr oil fed groups. Focal lesions were found in cardiac tissue of the rats, but not in liver and spleen tissue. The incidence of lesions was similar on all ration treatments. A significantly (P LESS THAN 0.01) higher incidence of cardiac lesions was found in male rats than in female rats.

Animals↗