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Biomedical subjects

J Dabrowski

Publications and source records attributed to J Dabrowski.

At least 37 records · Page 2Linked to original sources
PubMed1989

Solution conformation of sialosylcerebroside (GM4) and its NeuAc(alpha 2----3)Gal beta sugar component.

The solution conformations of GM4 ganglioside [NeuAc(alpha 2----3)Gal (beta 1----1)Cer] in (2H3C)2SO and its component disaccharide in 2H2O were investigated with the aid of 1H-nuclear magnetic resonance spectroscopy (nuclear Overhauser effect, analysis of coupling constants) and by energy-minimum calculations. The existence of three low-energy conformers obtained by theoretical calculations was supported by experimental findings in the case of GM4, whereas the disaccharide appears to exist as a mixture of two conformers.

Carbohydrate Conformation↗
PubMed1989

[The value of ultrasonography in the diagnosis of traumatic liver injuries].

The dramatic advances in ultrasonography has opened new diagnostic possibilities making possible assessment of the internal structure of parenchymal organs. Two cases of traumatic liver rupture are described, one was found accidentally, in the second case USG protected the patient from undergoing exploratory laparotomy. In view of the simplicity, speed and complete safety of the method it is a very useful diagnostic procedure helping in correct diagnosis.

Adult↗
PubMed1989

Structures of neutral O-linked polylactosaminoglycans on human skim milk mucins. A novel type of linearly extended poly-N-acetyllactosamine backbones with Gal beta(1-4)GlcNAc beta(1-6) repeating units.

O-Linked oligosaccharides were isolated from human skim milk mucins and from mucin-derived glycopeptides by reductive beta-elimination. The released alditols were fractionated by DEAE-Sephadex chromatography and purified by high performance liquid chromatography on primary amine bonded phase. The structures of the major neutral oligosaccharide alditols could be established by fast atom bombardment and electron impact mass spectrometry, combined with methylation analysis, 500-MHz 1H nuclear magnetic resonance spectroscopy, and endo-beta-galactosidase (from Bacteroides fragilis, EC 3.2.1.103) digestion (where n = 0-3): (formula; see text) Major O-glycosidically linked oligosaccharides on skim milk mucins are of the Gal beta(1-3)[GlcNAc beta(1-6)] GalNAc core type 2 and exhibit linearly extended backbone chains of the poly N-acetyllactosamine type comprizing up to at least four repeating units, which are linked by the hitherto unknown sequence GlcNAc-beta(1-6) Gal rather than GlcNAc beta(1-3)Gal. A considerable portion of neutral alditols is represented by branched isomers of the linear species, which are distinguished by their content of 3,6-disubstituted galactose and their partial resistance to endo-beta-galactosidase digestion.

Amino Sugars↗
PubMed1989

The structure of the lipopolysaccharide core region of Citrobacter 027.

The structure of Citrobacter 027 lipopolysaccharide core has been established using sugar and methylation analyses and 1H-NMR spectroscopy, and was shown to be identical to the core described recently in PCM 1487 strain which represents a separate serotype in Citrobacter genus.

Citrobacter↗
PubMed1989

Isolation and structural characterization of sialic-acid-containing glycopeptides of the O-glycosidic type from the urine of two patients with an hereditary deficiency in alpha-N-acetylgalactosaminidase activity.

Glycopeptides have been isolated from the urine of two patients, aged 5 and 6, with a new lysosomal storage disease characterized by a deficiency in alpha-N-acetylgalactosaminidase activity. Isolation of these glycopeptides was achieved using gel filtration and ion-exchange chromatography. Structural determination was done using one- and two-dimensional 500 MHz 1H-NMR spectroscopy and FAB mass spectrometry of native and derivatized glycopeptides. The following structures were inferred as being present: Glycopeptide A (up to 140 mg/l urine) (1)-(3) Neu5Ac alpha 2-3Gal beta 1-3 (Neu5Ac alpha 2-6)GalNAc alpha 1-R A1: R = Ser A2: R = Thr A3: R = Thr-Pro Glycopeptide B (up to 80 mg/l urine) (4)-(6) Neu5Ac alpha 2-3Gal beta 1-4GlcNAc beta 1-6 (Neu5Ac alpha 2-3-Gal beta 1-3) GalNAc alpha 1-R B1: R = Ser B2:R = Thr B3: R = Thr-Pro

Amino Acids↗
PubMed1989

Unbranched polylactosamino-O-glycans on human skim milk mucins exhibit Gal beta(1-4)GlcNAc beta(1-6) repeating units.

Neutral O-glycans on human skim milk mucins exhibit unique structural features, which may be summarized as follows: 1) the carbohydrate chains comprise up to 16 (or more) monosaccharide units; 2) the core structures are of the common type 2 Gal beta(1-3)[GlcNAc beta(1-6)]GalNAc; 3) the poly-N-acetyllactosamine backbones of the major glycans are unbranched; 4) the repetitive N-acetyllactosamine units of the linear species are linked by the hitherto unknown sequence GlcNAc beta(1-6)Gal rather than GlcNAc beta(1-3)Gal; 5) another major portion of mucin O-glycans represents branched isomers of the linear species containing except for their branching points at 3,6 disubstituted galactose residues the same structural elements as their unbranched counterparts; 6) fucosylation at various sites of the polyactosamine sequences yields mono-, di- and trifucosylated species; 7) fucosylation occurs predominantly at the subterminal GlcNAc and at the core-GlcNAc of the carbohydrate chain.

Carbohydrate Sequence↗
PubMed1988

Structure elucidation of blood group B-like and I-active ceramide eicosa- and pentacosasaccharides from rabbit erythrocyte membranes by combined gas chromatography-mass spectrometry; electron-impact and fast-atom-bombardment mass spectrometry; and two-dimensional correlated, relayed-coherence transfer, and nuclear Overhauser effect 500-MHz 1H-n.m.r. spectroscopy.

The structures of two glycosphingolipids, a ceramide eicosasaccharide BIrab-3 and a ceramide pentacosasaccharide BIrab-4 with "B-like" and distinct I blood-group activity, isolated in high yield from rabbit erythrocyte membranes, were investigated. The determination of their general structure, alpha-D-Galp-(1----3)-beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)- [alpha-D-Galp-(1----3)-beta-D-Galp-(1----4)-beta-D-Glcp-NAc-(1----6)]-be ta- D-Galp-(1----n4)-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-beta-D-Gl cp- (1----1)-ceramide, with n = 3 for BIrab-3 and n = 4 for BIrab-4, was based on the results of methylation analysis, fast-atom-bombardment and electron-impact mass spectrometry, 1D and 2D COSY, RCT, and n.O.e. 1H-N.m.r. spectra, and specific enzymic and chemical degradation.

ABO Blood-Group System↗
PubMed1988

Structure elucidation of the blood group B like and blood group I active octaantennary ceramide tetracontasaccharide from rabbit erythrocyte membranes by two-dimensional 1H NMR spectroscopy at 600 MHz.

The primary structure of the ceramide tetracontasaccharide (1) from rabbit erythrocyte membranes has been determined with the aid of 600-MHz two-dimensional phase-sensitive correlated, "totally correlated" (TOCSY, homonuclear Hartmann-Hahn), relayed coherence transfer, triple quantum filtered, and nuclear Overhauser enhancement 1H NMR spectra. It was shown that obtaining subspectra of the constituent sugar residues from a totally correlated spectrum and assigning the resonances occurring in these subspectra by analyzing the relevant cross-peaks in phase-sensitive correlated spectra is the most efficient way for establishing complex oligosaccharide structures. This analysis has shown 1 to be the highest homologue of the multiantennary neolactoglycosphingolipids of the following general formula with n = 7: (Formula: see text).

ABO Blood-Group System↗
PubMed1988

A two-dimensional 1H-n.m.r. (500 MHz) and 13C-n.m.r. (125 MHz) study of N-linked glycopeptides derived from calf fetuin.

The oligosaccharide part of an N-linked triantennary glycopeptide from calf fetuin with fourteen carbohydrate residues and its smaller derivatives obtained by successive enzymic cleavage of the terminal residues were investigated using 2D 1H-n.m.r. (500 MHz) and 13C-n.m.r. (125 MHz) spectroscopy. Assignments have been made of the resonances of almost all the protons of the constituent carbohydrate residues in these glycopeptides. A comparison of the 1H chemical shifts and coupling constants, as determined from the cross-peaks, has shown the dependence of these parameters on the interactions of spatially related neighbouring carbohydrates. Small conformational changes take place upon elongation of the oligosaccharide side-chains.

Carbohydrate Conformation↗
PubMed1988

[Effects of carbachol and atropine on bile secretion in sheep].

Experiments were performed on rams prepared surgically to make possible the control of bile flow and the maintenance of enterohepatic circulation of bile components. Carbachol and atropine were infused into the jugular vein for 2 hours in the amounts: 0.3 and 0.7 microgram/kg b.w./min. respectively. Carbachol administration did not affect significantly the bile production. Atropine led to the significant decrease in the bile flow (p less than 0.01) by diminished concentration of bile acids in the bile. On the basis of the obtained results the role of n. vagus in the regulation of biliary secretion is discussed. It is suggested, that in physiological conditions the biliary secretion is, to some extent, maintained as a result of the muscarinic receptor stimulation. This stimulation attains the maximum level and it is not possible to evoke rise in bile production after either n. vagus stimulation or administration of parasympathomimetic agents.

Animals↗
PubMed1987

MS and NMR analysis of the cross-reacting determinant glycan from Trypanosoma brucei brucei MITat 1.6 variant specific glycoprotein.

The cross-reacting determinant glycan from Trypanosoma brucei brucei MITat 1.6 is known to contain galactose, mannose and non-acetylated glucosamine. The structural elucidation of this oligosaccharide has been impeded by an unusual non-glycosidic linkage to the peptide chain and a glycosidic linkage to inositol phosphate on either side of the oligosaccharide. Using two different approaches for the isolation of the glycan, namely hydrolysis to give the oligosaccharide directly or pronase digestion to yield the glycan-containing C-terminal glycophosphopeptide, the structure of this glycan was elucidated by mass spectrometry and 1H-NMR spectroscopy. There was evidence of heterogeneity in the glycan residue.

Animals↗