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Biomedical subjects

C A Bush

Publications and source records attributed to C A Bush.

At least 37 records · Page 2Linked to original sources
PubMed1995

Coronary artery fistulas in adults: incidence, angiographic characteristics, natural history.

The incidence, angiographic characteristics, and natural history of coronary artery fistulas in patients undergoing diagnostic cardiac catheterization have not been well defined. Of 33,600 patients who had diagnostic cardiac catheterization, 34 (0.1%) had coronary artery fistula. Nineteen fistulas originated from the right, 11 from the left anterior descending, and 4 from the circumflex coronary arteries, respectively. The mean ratio of pulmonary to systemic flow was 1.19 +/- 0.33. Only one patient with coexistent atrial septal defect had a pulmonic to systemic flow ratio > 1.5. Right and left heart pressures, with the exception of three patients in whom left ventricular end-diastolic pressures was > 12 mm Hg, were within normal limits. During a mean follow-up period of 6.3 years (range 2-14 years), there were no complications related to coronary artery fistula. It was concluded that the incidence of coronary artery fistulas detected during diagnostic coronary angiography is very low. Coronary artery fistulas originate predominantly from the right coronary artery and are not associated with hemodynamic abnormalities or other congenital heart diseases. The prognosis of coronary artery fistulas in adults is good.

Adult↗
PubMed1995

Lectin recognition of host-like saccharide motifs in streptococcal cell wall polysaccharides.

Viridans streptococci that participate in the microbial colonization of teeth have cell wall polysaccharides composed of linear phosphodiester-linked hexa- or heptasaccharide repeating units, each containing a host-like disaccharide motif, either Gal beta 1-->3GalNAc or GalNAc beta 1-->3Gal. Whereas strains with GalNAc beta 1-->3Gal-containing polysaccharides co-aggregated with streptococci that possess GalNAc-sensitive lectins, strains with either host-like motif co-aggregated with Actinomyces spp. The latter interactions reflected the specificity of Actinomyces spp. lectins for common features of Gal beta 1-->3GalNAc and GalNAc beta 1-->3Gal. Thus, alpha-linked glycosides of both disaccharides were much more potent inhibitors of co-aggregation than Gal or GalNAc. Six non-bacterial lectins also reacted with the streptococcal polysaccharides. In general, precipitation of each lectin with each polysaccharide involved binding of Gal or GalNAc within the host-like motifs, but not saccharides outside these regions. The lectins of Ricinus communis, Abrus precatorius, Codium fragile and Agaricus bisporus were most reactive with the Gal beta 1-->3GalNAc-containing polysaccharides, the Wisteria floribunda lectin with the GalNAc beta 1-->3Gal-containing polysaccharides and the Bauhinia purpurea lectin with polysaccharides containing either disaccharide. Thus, lectin recognition of the streptococcal cell wall polysaccharides involved either the common or specific sides of the Gal beta 1-->3GalNAc and GalNAc beta 1-->3Gal motifs present within these molecules.

Actinomyces↗
PubMed1995

Preliminary structure determination of the capsular polysaccharide of Vibrio cholerae O139 Bengal Al1837.

Vibrio cholerae O139 Bengal has recently been identified as a cause of epidemic cholera in Asia. In contrast to V. cholerae O1, V. cholerae O139 Bengal has a polysaccharide capsule. As determined by high-performance anion-exchange chromatography and 1H nuclear magnetic resonance analysis, the capsular polysaccharide of V. cholerae O139 Bengal strain Al1837 has six residues in the repeating subunit; this includes one residue each of N-acetylglucosamine, N-acetylquinovosamine (QuiNAc), galacturonic acid (GalA), and galactose and two residues of 3,6-dideoxyxylohexose (Xylhex). The proposed structure is [formula: see text]

Bacterial Capsules↗
PubMed1994

Molecular dynamics simulation of oligosaccharides containing N-acetyl neuraminic acid.

alpha D-N-acetyl neuraminic acid (Neu5Ac, sialic acid) is a commonly occurring carbohydrate residue in various cell surface glycolipids and glycoproteins. This residue is linked terminally or internally to Gal residues via an alpha(2-->3) or alpha(2-->6) linkage. In the cell surface receptor, sialyl-LewisX, a terminal alpha(2-->3) linkage is present. Previous studies from our laboratory have shown that in solution LewisX adopts a relatively rigid structure. In order to model the Neu5Ac residue, vacuum molecular dynamics of this monosaccharide were compared with simulations that explicitly include solvent water. The dynamical average of the monosaccharide conformation obtained from the two simulations was similar. Vacuum calculations for the disaccharide Neu5Ac alpha(2-->3) Gal beta-O-methyl show that a number of low energy minima are accessible to this disaccharide. Molecular dynamics simulations starting from the low energy minima show conformational transitions with a time scale of 10-50 ps among several of the minima while large barriers between other minima prevent transitions on the time scale studied. Simulations of this disaccharide in the presence of solvent show fewer conformational transitions, illustrating a dampening effect of the solvent that has been observed in some other studies. Our results are most consistent with an equilibrium among multiple conformations for the Neu5Ac alpha(2-->3) Gal beta linkage.

Carbohydrate Conformation↗
PubMed1994

Conformation of the oligosaccharide receptor for E-selectin.

A tetrasaccharide related to the blood group oligosaccharides, known as sialyl LewisX, has been proposed as the receptor for the lectin responsible for leukocyte adhesion named alternatively as E-selectin or ELAM-1. The 13C- and 1H-nmr spectra have been completely assigned for a tetrasaccharide model of this receptor, Neu5Ac alpha-(2-->3)-Gal beta-(1-->4)-[Fuc alpha-(1-->3)-]GlcNAc beta-NHAc. Quantitative nuclear Overhauser data (NOESY) have been recorded and analyzed by a complete spin matrix simulation method. Conformational space was exhaustively searched and all conformational models whose simulated NOESY spectra matched the experiment were found. Molecular mechanics and molecular dynamics calculations were carried out to test whether the experimental conformations are low energy and thus likely to represent true single conformations for the tetrasaccharide. It was concluded that while the LewisX trisaccharide portion of the compound adopts a single conformation, there is likely to be some flexibility about the Neu5Ac alpha-(2-->3)-linkage. A model featuring fast exchange between two different conformations of this linkage is found to be consistent with both the nmr experiments and the molecular dynamics simulations.

Carbohydrate Conformation↗
PubMed1994

Measurement of long-range2 13C-1H coupling constants of 95% uniformly 13C-labeled polysaccharide from Streptococcus mitis J22.

The coaggregation of Streptococcus mitis strain J22 in the early stages of dental plaque formation has been shown to result from interaction of cell wall polysaccharides with lectins on the surface of other oral bacterial species. This bacterium was grown in a medium containing 13C as the sole carbon source. We have isolated the lectin receptor polysaccharide from this strain with full enrichment in 13C and have determined a number of two-bond and three-bond 13C-1H coupling constants from measurements of the offsets in two-dimensional homonuclear nmr spectra [exclusive correlated spectroscopy (E-COSY) method]. A scheme for reliable extraction of these coupling constants from homonuclear Hartmann-Hahn and nuclear Overhauser effect spectroscopy spectra is tested in model compounds. We interpret the three-bond coupling across the glycosidic linkage in terms of dihedral angles in order to provide conformational information to supplement molecular modeling and nuclear Overhauser effect data. We show that the E-COSY method works well even for coupling constants smaller than the nmr line width and that a number of the 3JCH across the glycosidic linkage are in the range of 1-2 Hz, which is much smaller than many previously reported values.

Carbohydrate Conformation↗
PubMed1994

The cell wall polysaccharide of Streptococcus gordonii 38: structure and immunochemical comparison with the receptor polysaccharides of Streptococcus oralis 34 and Streptococcus mitis J22.

As part of our ongoing investigations involving lectin-mediated adhesion among oral bacteria, the receptor polysaccharide from Streptococcus gordonii 38 was isolated and characterized. Carbohydrate analysis of the hydrolysed S. gordonii 38 polysaccharide by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) showed galactose (Gal) (2 mol), N-acetylgalactosamine (GalNAc) (1 mol), rhamnose (Rha) (2 mol), glucose (Glc) (1 mol) and galactosamine-6-phosphate (1 mol). Mild acid hydrolysis of the polysaccharide yielded a heptasaccharide repeating unit. The structure of the heptasaccharide repeating unit was determined by high-resolution NMR spectroscopy which includes various homonuclear (DQF-COSY, TQF-COSY, NOESY and HOHAHA) and heteronuclear experiments (HMQC), including linkage assignments by 1H-13C long-range correlation (HMBC). Complete 1H and 13C NMR assignments for the intact polysaccharide yielded the covalent structure of a heptasaccharide repeating unit: [Formula: see text] The structure of the strain 38 polysaccharide is closely related to those of Streptococcus mitis J22 and Streptococcus oralis 34. Thus, the difference between the strain 38 and J22 heptasaccharides was at their reducing ends, with GaLNAc beta-(1-->3)-Gal in the former and Gal beta-(1-->3)-GalNAc in the latter, while the difference between the 38 heptasaccharide and 34 hexasaccharide was at the non-reducing ends, where a rhamnose branch occurred in the former but not the latter structure. When compared by their quantitative precipitin curves with rabbit antibodies against each streptococcal strain, the strain 38 polysaccharide reacted more like the polysaccharide of strain J22 than that of strain 34. In contrast, each strain was recognized by the Gal- and GalNAc-reactive lectins of Actinomyces spp., but only strains 38 and 34 were recognized by GalNAc-sensitive lectins of other streptococci. These findings strongly support the hypothesis that the immunogenic features of these polysaccharides are distinct from those detected by lectin binding.

Animals↗
PubMed1993

Determination by heteronuclear NMR spectroscopy of the complete structure of the cell wall polysaccharide of Streptococcus sanguis strain K103.

Although complete structures of complex polysaccharides have traditionally been determined by chemical degradative methods, a number of recent developments in instrumentation have greatly facilitated this task. We illustrate the application of several of these methods in a determination of the complete covalent structure of the polysaccharide from Streptococcus sanguis K103, which is composed of an octasaccharide repeating subunit linked by phosphodiester bonds. Carbohydrate analysis by HPAE-PAD and by reverse-phase chromatography of benzoylated derivatives of the hydrolysis products of the polysaccharide gave glucose (3 mol), galactose (1 mol), rhamnose (2 mol), N-acetylglucosamine (1 mol), and galactose 6-phosphate (1 mol). Circular dichroism of the O-benzoylated monosaccharides showed the absolute configurations to be D for all residues except for rhamnose, which is L. The 1H NMR spectrum was completely assigned by two-dimensional homonuclear methods (DQF-COSY, NOESY, HOHAHA). The stereochemistry of pyranosides was assigned from 3JHH coupling constant values determined from these experiments. The 13C spectrum was assigned by 1H-detected heteronuclear multiple-quantum correlation (1H[13C] HMQC) and by the hybrid method of HMQC-COSY. The glycosidic linkage positions of the polymer were determined by 1H-detected multiple-bond correlation (1H[13C] HMBC) and by 2D-NOESY spectra. The position of the phosphodiester linkage was determined by splitting observed in the 13C resonances due to 31P couplings leading to the overall structure given in Chart I.

Acetylglucosamine↗
PubMed1993

Cardiac catheterization and coronary angiography using 5 French preformed (Judkins) catheters from the percutaneous right brachial approach: a comparative analysis with the femoral approach.

This study describes a method for the performance of cardiac catheterization using 5 French preformed Judkins catheters from a percutaneous right brachial approach, and compares that technique to the more traditional percutaneous right femoral approach with 6 French catheters. One hundred consecutive patients requiring diagnostic left heart catheterization and selective coronary angiography were randomized according to femoral versus brachial arterial technique. Procedural efficiency, radiation exposure, and diagnostic film quality favored the femoral approach, while patient comfort, hemostasis time, time to ambulation, and decreased need for post-procedure nursing care favored the brachial approach. No differences were identified in complications. Cardiac catheterization from a right brachial artery percutaneous approach with 5 French preformed catheters has both advantages and disadvantages when compared with a more traditional femoral approach with 6 French catheters. Multiple factors should be considered before selecting an approach to diagnostic cardiac catheterization and each patient should be individually evaluated for determination of the optimal technique.

Brachial Artery↗
PubMed1993

Capsular polysaccharide structure of a clinical isolate of Vibrio vulnificus strain BO62316 determined by heteronuclear NMR spectroscopy and high-performance anion-exchange chromatography.

Virulence of Vibrio vulnificus has been strongly associated with encapsulation. Capsular polysaccharide was purified from a virulent strain of Vibrio vulnificus BO62316, a clinical isolate, by dialysis, centrifugation, enzymatic digestion, and phenol-chloroform extraction. This polysaccharide shows partial reactivity with antibodies to the capsular polysaccharide of a related pathogenic strain of V. vulnificus (MO6-24) whose structure was recently reported. Nuclear magnetic resonance spectroscopic analysis of the purified polysaccharide from strain BO62316 showed that the polymer is composed of a repeating structure with four sugar residues per subunit: a residue of 2-acetamido-2,6-dideoxy-hexo pyranose in the alpha-gluco configuration (QuiNAc), a residue of 2-acetamido-2,6-dideoxy hexopyranose in the alpha-galacto configuration (FucNAc), a residue of 2-acetamido-2,6-dideoxy hexopyranose in the alpha-manno configuration (RhaNAc), and a residue of 2-acetamido-2,6-dideoxy hexouronate in the alpha-galacto configuration (GalNAcA). The complete carbohydrate structure of the capsular polysaccharide was determined by heteronuclear nuclear magnetic resonance spectroscopy and by high-performance anion-exchange chromatography. The 1H and 13C spectra were completely assigned, and vicinal coupling relationships were used to establish the stereochemistry of each sugar residue, its anomeric configuration, and the position of the glycosidic linkages. The complete structure is Formular; [see text]. This is the first reported occurrence of RhaNAc in a capsular polysaccharide.

Carbohydrate Conformation↗
PubMed1993

Capsular types of Vibrio vulnificus: an analysis of strains from clinical and environmental sources.

Vibrio vulnificus produces a capsular polysaccharide (CPS) that is essential for virulence. CPS from V. vulnificus clinical strain MO6-24 has been purified and the structure determined. In preliminary screening with antisera raised to MO6-24 CPS, 4 (19%) of 21 clinical isolates (including MO6-24), but none of 67 environmental V. vulnificus isolates, agglutinated with anti-MO6-24 antisera (P = .003). CPS was isolated from a subset of 12 clinical and 7 environmental isolates and analyzed by high-performance anion-exchange chromatography and one-dimensional nuclear magnetic resonance. MO6-24 and 1 other serologically positive strain had identical CPS structures; the other 2 serologically positive strains had substitutions in two of four sugar residues. Thirteen other capsular types were identified among the remaining 15 strains from which CPS was extracted.

Agglutination Tests↗
PubMed1993

Same-day admission for cardiac surgery: a benefit to patient, family, and institution.

A pilot program was conducted in an effort to understand the advantages of admitting patients requiring cardiac surgery on the day of the scheduled surgical procedure. A total of 143 patients over a 4-month period were admitted on the day of surgery. Patients required repair of atrial septal defect (adult), coronary artery bypass grafts, and/or heart valve replacements. Patients, family members, and significant others verbalized positive feelings about the program. Both nurses and physicians assert that a high quality of patient care was rendered through this program. Additionally, the institution realized some financial gain by reducing the length of stay for each patient by at least 1 day.

Adult↗
PubMed1993

Structure of ten free N-glycans in ripening tomato fruit. Arabinose is a constituent of a plant N-glycan.

The concentration-dependent stimulatory and inhibitory effect of N-glycans on tomato (Lycopersicon esculentum Mill.) fruit ripening was recently reported (B. Priem and K.C. Gross [1992] Plant Physiol 98: 399-401). We report here the structure of 10 free N-glycans in mature green tomatoes. N-Glycans were purified from fruit pericarp by ethanolic extraction, desalting, concanavalin A-Sepharose chromatography, and amine-bonded silica high performance liquid chromatography. N-Glycan structures were determined using 500 MHz 1H-nuclear magnetic resonance spectroscopy, fast atom bombardment mass spectrometry, and glycosyl linkage methylation analysis by gas chromatography-mass spectrometry. A novel arabinosyl-containing N-glycan, Man alpha 1-->6(Ara alpha 1-->2)Man beta 1-->4GlcNAc beta 1-->4(Fuc alpha 1-->3)GlcNAc, was purified from a retarded concanavalin A fraction. The location of the arabinosyl residue was the same as the xylosyl residue in complex N-glycans. GlcNAc[5']Man3(Xyl)GlcNAc(Fuc)GlcNAc and GlcNAc[5']Man2GlcNAc(Fuc)GlcNAc were also purified from the weakly retained fraction. The oligomannosyl N-glycans Man5GlcNAc, Man6GlcNAc, Man7GlcNAc, and Man8GlcNAc were purified from a strongly retained concanavalin A fraction. The finding of free Man5GlcNAc in situ was important physiologically because previously we had described it as a promoter of tomato ripening when added exogenously. Mature green pericarp tissue contained more than 1 microgram of total free N-glycan/g fresh weight. Changes in N-glycan composition were determined during ripening by comparing glycosyl and glycosyl-linkage composition of oligosaccharidic extracts from fruit at different developmental stages. N-Glycans were present in pericarp tissue at all stages of development. However, the amount increased during ripening, as did the relative amount of xylosyl-containing N-glycans.

Carbohydrate Sequence↗
PubMed1992

Solution structure of the Lewis x oligosaccharide determined by NMR spectroscopy and molecular dynamics simulations.

The Lewis x (Lex) determinant is a trisaccharide fragment that has been implicated as a specific differentiation antigen, as a tumor antigen, and as a key component of the ligand for the endothelial leukocyte adhesion molecule, ELAM-1. High-resolution nuclear magnetic resonance spectroscopy shows it to have a relatively rigid structure. Only a small range of glycosidic dihedral angles in the trisaccharide produce simulated nuclear Overhauser effect spectra agreeing with data measured for the human milk pentasaccharide, lacto-N-fucopentaose-3, which contains the Lex determinant. Independently, the same average structure for the Lex determinant arises from in vacuo molecular dynamics simulations. The proposed conformation of the Lex trisaccharide is very similar to that recently determined for the closely related Lea trisaccharide. In agreement with the recent finding that both sialylated Lea and Lex react with ELAM-1, the results presented here show that the Lea and Lex determinants contain very similar carbohydrate domains.

Carbohydrate Conformation↗
PubMed1992

Conformations of type 1 and type 2 oligosaccharides from ovarian cyst glycoprotein by nuclear Overhauser effect spectroscopy and T1 simulations.

To probe differences in conformation of the type 1 and type 2 linkages in blood group oligosaccharides, two-dimensional nuclear Overhauser effect spectroscopy (2D-NOESY) and 1H T1 data were obtained for two blood group A oligosaccharide alditols containing the type 1 and type 2 linkage. The NOE data were interpreted using a complete relaxation matrix approach. Simulations of NOE and T1 values were made using disaccharide and tetrasaccharide model conformations generated by a systemic variation of the glycosidic dihedral angles phi and psi. NOEs from the amide protons of GlcNAc and GalNAc in the type 1 pentasaccharide alditol were obtained, and simulated in a manner similar to those from carbon-bound protons. In addition to providing data for determining the conformation of the type 1 linkage from amide proton NOEs of GlcNAc and GalNAc to neighboring residues, amide proton NOEs also yield information on the orientation of the acetamido side chains. The amide NOE data indicated subtle differences in the orientation of the amide side chain of GlcNAc among the A type 1 pentasaccharide alditol and two previously studied blood group oligosaccharides, lacto-N-difucohexaose 1 and lacto-N-fucopentaose 1. From the NOE and 1H T1 data, and from simple rigid geometry energy calculations, it is concluded that the type 1 and type 2 linkages in the oligosaccharides studied have different conformations and that these conformations are relatively rigid in solution.

ABO Blood-Group System↗