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Biomedical subjects

K Bock

Publications and source records attributed to K Bock.

At least 127 records · Page 7Linked to original sources
PubMed1983

Mercury iodide as a catalyst in oligosaccharide synthesis.

The disaccharide 4-O-alpha-D-mannopyranosyl-alpha-L-rhamnopyranose and the trisaccharide 2-O-alpha-D-galactopyranosyl-4-O-beta-D-mannopyranosyl-alpha-L-rhamno pyranose determinants, which are analogs of the repeating unit of Salmonella sero-group A, B and D, have been synthesized using mercury(II) iodide as a catalyst in the glycosylation reaction. The reducing end of the di- and the trisaccharide was substituted with a linking arm for covalent attachment to a protein carrier. Reaction of 8-ethoxycarbonyloct-1-yl 2,3-di-O-benzoyl-alpha-L-rhamnopyranoside with acetobromomannose in the presence of mercury(II) iodide gave, after deprotection, the disaccharide in 49% yield. The trisaccharide was prepared by a block synthesis in which 6-O-acetyl-4-O-allyl-2-O-(6-O-acetyl-2-O-allyl-3,4-di-O-benzoyl-alpha-D- galactopyranosyl)-3-O-benzyl-alpha-D-mannopyranosyl bromide (21) and 8-methoxycarbonyloct-1-yl 2,3-O-cyclohexylidene-alpha-L-rhamnopyranoside were condensed in the presence of mercury(II) iodide. These conditions gave the trisaccharide (26) in 26% yield. The disaccharide 21 was prepared by mercury(II) iodide catalyzed condensation of the protected galactopyranosyl bromide (15) and 4-O-allyl-1,6-anhydro-3-O-benzyl-beta- D-mannopyranose followed by acetolysis and reaction with titanium tetrabromide.

Antigens, Bacterial↗
PubMed1983

Schistosomiasis: proline production and release by ova.

The production and release of proline was measured in cleaned ova of Schistosoma mansoni. Proline was found to be released at approximately 76 mumoles/100 cc of ova water/hr. This high rate of proline production was found to correlate with extremely active proline synthetic enzymes in the ova. Ornithine-delta-transaminase, which converts ornithine to delta 1-pyrroline-5-carboxylic acid, was found to be twice that of adult schistosomes and over seven times that of rat liver. delta 1-pyrroline-5-carboxylic acid reductase, which converts delta 1-pyrroline-5-carboxylic acid to proline, is also more active than the adult isoenzyme and 35 times more active than the rat liver isoenzyme. These data suggest that proline emanating from the ova may play a role in stimulating fibrosis in the granulomata of schistosomiasis.

Animals↗
PubMed1981

Tolfenamic acid. Detection and structure of urinary metabolites.

N-(2-Methyl-3-chlorophenyl)anthranilic acid (tolfenamic acid) and its metabolites in serum and urine were analyzed by a reversed-phase ion-pair HPLC method. The major metabolites were N-(2-methyl-3-chloro-4-hydroxyphenyl)anthranilic acid, and one of the minor metabolites was N-(2-formyl-3-chlorophenyl)anthranilic acid, i.e., products resulting from hydroxylation in either the methyl group or the methylchlorophenyl group of tolfenamic acid, and further oxidation of the hydroxymethyl group to a formyl group.

Adult↗
PubMed1979

The conformations of the Lewis blood group determinants, sucrose and kanamycin A.

The main purpose is to illustrate the potential, in terms of structure and conformational analysis in the general area of carbohydrate chemistry, presented by the new generation of high frequency FT nuclear magnetic resonance spectrometers based in the highly stable magnetic fields generated by superconducting solenoids. In the case of the LEWIS human blood group antigenic determinants, specific interunit deshielding effects on 1H-chemical shifts and specific interunit nuclear OVERHAUSER enhancements of 1H-signals allowed specific assignments of overall conformations for these branched oligosaccharides. Furthermore, these conformations are shown to be well anticipated by way of simple hard-sphere calculations but taking into consideration important contributions by the exo-anomeric effect in the assignment of conformational preferences at the glycosidic bonds. The presence of an intramolecular hydrogen bond between OH-2g and OH-1f for sucrose dissolved in dimethylsulfoxide-d6(DMSO-d6) is demonstrated by examining the spectrum of a solution which has near 50% of the OH groups in the OD form. The 1H-signals in the structural unit Clf-O-H comes from O(C2g)-H comes from DMSO-d6 are shown to be deuterium shifted by 0.005-0.007 ppm when in the forms Clf-O-H comes from O(C2g)-D comes from DMSO-d6 (deshielded) and Clf-O-D comes from O(C2g)-H comes from DMSO-d6 (shielded). These small shifts were readily discerned at 400 MHz. The (1H)(400 MHz) and 13C (100 MHz) spectra of kanamycin A both as the free amine and the sulfate salt are presented to illustrate how modern nuclear magnetic resonance spectroscopy together with interpretations based in conformational analysis may allow the elucidation of the structures (except for the absolute configuration) of such substances. It is demonstrated that the effect on 13C chemical shifts of the protonation of the amino groups can provide useful clues as to their relative dispositions in three-dimensional space.

Chemical Phenomena↗
PubMed1975

[Blood coagulation tests in children with cyanotic heart defects].

In 57 children with congenital cyanotic heart disease coagulation analyses were performed before operation. The patients with low haematocrit only sometimes exhibited defects of low degree. In patients with haematocrit values of more than 60% were increasingly found complex coagulation disturbances. Many correlations could be proved between the coagulation parameters. Thrombocytopenia, plasmatic defects and hyperfibrinolysis were parallel. The cause of the changes is to be seen in chronic disseminated intravasal coagulation processes. The results of investigations presented confirm the necessity of preoperative coagulation analyses especially in patients with high haematocrit values. Larger disturbances of coagulation may influence the decision between a palliative intervention or immediate causal operation.

Blood Cell Count↗
PubMed1975

[Results following surgery of fibrous subvalvular aortic stenosis in childhood and adolescence].

From 1963 up to the end of June 1974 32 patients were operated on for fibrous subvalvular aortic stenosis in Leipzig (age at operation 6-17 years). 18 patients had concomitant cardiovascular malformations, 4 patients died. The results are discussed in detail. Contrary to other publications the authors adopt the attitude that the operation in subvalvular stenosis is to be recommended even with gradients as low as 50 mm Hg, particularly when haemodynamically significant concomitant malformations are present. Therefore, the measuring of the left ventricular pressure and the localisation of the stenosis by intracardiac diagnostics should be performed not too late. It may be possible that the measuring of the left ventricular pressure must be repeated some years later. Also for the exact evaluation of the post-operative results recatheterisations are necessary.

Adolescent↗