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Biomedical subjects

C A Bush

Publications and source records attributed to C A Bush.

At least 73 records · Page 4Linked to original sources
PubMed1987

Aortic distensibility abnormalities in coronary artery disease.

Vasodilatory capacity of nonstenotic arteries in experimental animals with atherosclerosis is decreased. It was postulated that aortic distensibility may be abnormal in patients with coronary artery disease (CAD). Aortic distensibility was determined in 24 normotensive patients with CAD and an angiographically normal aorta and values were compared with those in 18 age-matched normal subjects. Aortic diameters were measured at 3 levels--2, 4 and 6 cm above the aortic valve--by angiographic techniques. The area of the first 6 cm of the aorta above the aortic valve was planimetered and mean aortic diameters were calculated. Distensibility was calculated using the formula: [2 X (changes of the aortic diameter)/(diastolic aortic diameter) X (changes of the aortic pressure)]. CAD patients had similar aortic pressures but markedly lower distensibility than normal subjects: 0.7 +/- 0.2 vs 1.7 +/- 0.3 (p less than 0.02); 1.5 +/- 0.3 vs 4.0 +/- 0.6 (p less than 0.02); and 1.2 +/- 0.2 vs 5.3 +/- 0.6 (p less than 0.001) at 2, 4 and 6 cm above the aortic valve, respectively. Distensibility was also calculated from the mean aortic diameters and was greater in normal subjects than in CAD patients (3.4 +/- 0.4 vs 1.6 +/- 0.1, p less than 0.001). Decreased aortic distensibility in CAD may be related to the common atherosclerotic process or to reduced ascending aorta vasa vasorum flow from coronary arteries.

Adult↗
PubMed1986

Evidence for progression from mild to severe mitral regurgitation in mitral valve prolapse.

Little information is available concerning the progression of mild to severe mitral regurgitation (MR) in patients with mitral valve prolapse (MVP). This study reports 86 patients, average age 60 years, who presented with cardiac symptoms, precordial systolic murmur, severe MR and a high incidence of MVP on echocardiography (57 of 75 [75%] ) and left ventriculography (61 of 84 [73%] ). Seventy-five surgically excised mitral valves appeared grossly enlarged and floppy. Histologic studies showed extensive myxomatous changes throughout the leaflets and chordae. Eighty patients had had precordial murmurs first described at average age 34 years, but the average age at which symptoms of cardiac dysfunction appeared was 59. However, once symptoms developed, mitral valve surgery was required within 1 year in 67 of 76 patients who had undergone surgery. Atrial fibrillation, present in 48 of 86 patients (56%), or ruptured chordae tendineae, present in 39 of 76 patients (51%), may have contributed to this rapid progression and deterioration. Additionally, 13 patients had a remote history of documented infective endocarditis. Twenty-eight patients had at least 1 type of serial clinical evaluation that indicated progressive MR in all 28 patients on the basis of changing auscultatory findings (24 of 26), progressive radiographic cardiomegaly (24 of 25), echocardiographic left atrial enlargement (4.3 to 5 cm in 11 patients) and angiographically worsening MR (14 of 15). Twenty-four of these patients had evidence of MVP on at least 1 of their initial studies. Thus, mild MR due to MVP and myxomatous mitral valves is a progressive disease in some patients with MVP.

Adult↗
PubMed1986

Purification and primary sequences of the major arginine-containing antifreeze glycopeptides from the fish Eleginus gracilis.

An Arg-containing antifreeze glycoprotein from the polar fish Eleginus gracilis was isolated, and the major components were purified to homogeneity. The general protocol for purification was chromatography of serum on DEAE-cellulose, followed by chromatography on a cation exchanger. DEAE-cellulose chromatography resulted in two fractions, A and B. Fraction A contained most of the antifreeze glycoprotein found in E. gracilis (approximately 80% by weight) and consisted of 13 distinct components. Unlike antifreeze glycoproteins from other previously studied polar fish, Fraction A contained both low and high molecular weight antifreeze glycoprotein components. The two major components of Fraction A were sequenced and compared with the sequence of antifreeze glycoproteins 7 and 8 from both Boreogadus saida and Pagothenia borchgrevinki. The antifreeze glycoproteins from E. gracilis were shown to have a similar composition to those previously studied, except for an additional Ala-Arg dipeptide at the carbon terminal in the major components of Fraction A and the position of Pro in the low molecular weight components. The activity of E. gracilis antifreeze glycoproteins is the subject of a companion article (Burcham, T. S., Osuga, D. T., Yeh, Y., and Feeney, R. E. (1986) J. Biol. Chem. 261, 6390-6397).

Amino Acid Sequence↗
PubMed1986

Characterization of the oligosaccharide alditols from ovarian cyst mucin glycoproteins of blood group A using high pressure liquid chromatography (HPLC) and high field 1H NMR spectroscopy.

A combination of reverse phase and normal phase high pressure liquid chromatography has been used to separate the reduced oligosaccharides produced by alkaline borohydride degradation of a blood group A ovarian cyst mucin glycoproteins. Fourteen compounds, ranging in size from a monosaccharide to a decasaccharide, have been isolated preparatively using a Zorbax C-18 reverse phase column eluted with water and a MicroPak AX-5 normal phase column eluted with aqueous acetonitrile. The purity of the products and their structures were determined from the fully assigned high field proton NMR spectra. The resonances of exchangeable amide protons, observed by the Redfield selective pulse sequence in H2O, were assigned by decoupling to the resonances of H2 of the 2-acetamido sugars. Nuclear Overhauser effects were used to establish the relationship of the anomeric protons and those of the aglycone. In exception to earlier proposals that nuclear Overhauser effect on irradiation of the anomeric proton should always be observed at the proton attached to the aglycone carbon, we find that for the linkage of GalNAcp(1----3)Gal, nuclear Overhauser effect on irradiation of the alpha-anomeric proton resonance is observed not at H3 but at H4 of galactose. A combination of NMR methods and enzymatic degradation was employed to determine the structures of 13 different oligosaccharides of which seven have not previously been reported. These oligosaccharides, which terminate with beta-Gal, alpha-Fuc, beta-GlcNAc, and alpha-GalNAc, account for 75% of the total glycoprotein carbohydrate, the remainder being isolated as a mixture of glycopeptides and a high molecular weight polysaccharide whose NMR spectrum implies a simple repeating subunit structure closely related to that of the oligosaccharides.

Adenocarcinoma, Mucinous↗
PubMed1986

In vivo validation of the origin of the esophageal electrocardiogram.

Esophageal electrocardiography is a clinical and investigational technique that is useful for determining atrial conduction intervals, analyzing atrial rhythms and mapping conduction pathways. Although the left atrial origin of the esophageal electrocardiogram has long been implied, recently that origin has been questioned. In the present study, the origin of the esophageal deflection is defined by direct right and left atrial mapping studies performed with simultaneous esophageal electrograms obtained from three positions (high, mid and low). Seven patients with normal left atrial dimensions (group I) and five patients with left atrial enlargement (group II) underwent transseptal catheterization during the course of electrophysiologic study. In group I (normal left atrial dimensions), conduction time from the high right atrium to each of the three esophageal positions corresponded to conduction times to left atrial sites ranging from 1 to 3 cm lateral to the left interatrial septum. The mid- and low esophageal conduction times were all significantly longer than conduction time to the left side of the septum (p less than 0.05). In group II (enlarged left atrium), conduction times to each of the esophageal sites corresponded to conduction times to left atrial sites lying between the mid-left atrium and a point 1 cm lateral to the left side of the septum. A significant trend toward longer conduction time to the mid-esophageal position than to the left septum was noted (p less than 0.1). In both groups, conduction times measured with the esophageal catheter were significantly longer than conduction time to the right interatrial septum (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Conformation of the glycotripeptide repeating unit of antifreeze glycoprotein of polar fish as determined from the fully assigned proton n.m.r. spectrum.

With its simple glycotripeptide repeating structure the antifreeze glycoprotein of polar fish may be an especially simple conformational mode for mucin glycoproteins with similar but more complex structures. The fully assigned proton n.m.r. spectrum confirms the anomeric configurations of the hexapyranosidic sugars of the side chains and the coupling constants of the alpha GalNAc and the beta Gal residues show both to be in the expected 4C1 chair conformation. The assignment of a single resonance for each proton of the (Ala-Thr-Ala)n repeat unit coupled with the observation of long range nuclear Overhauser effects (n.O.e.) implies a three-fold repeating conformation. The resonances of the two alanines are distinct and can be assigned to their correct positions in the peptide sequence by n.O.e. observed at the amide proton resonances on saturation of the alpha proton signals. The amide proton coupling constants of all three peptide residues are similar and imply a limited range of peptide backbone torsion angles, phi CN. The large n.O.e. which has been observed between the amide proton and the alpha proton of the residue preceding it in the sequence implies large positive values for the peptide dihedral angle, psi CC. Limits are placed on possible values of side chain dihedral angles by the observation of the coupling constant between the alpha and beta protons of the threonyl residue. The observation of n.O.e. between the anomeric proton of GalNAc and the threonyl side chain protons gives information on the conformation of the alpha glycosidic linkage between the disaccharide and the peptide. n.O.e. observed between the protons of the beta glycosidic linkage indicates the conformation of the disaccharide and the large amide proton coupling constant of the GalNAc residue shows a trans proton relationship. The spectroscopically derived data have been combined with conformational energy calculations to give a conformational model for antifreeze glycoprotein in which the hydrophobic surfaces of the disaccharide side chains are wrapped closely against a three-fold left handed helical peptide backbone. The hydrophilic sides of the disaccharides are aligned so that they may bind to the ice crystal face, which is perpendicular to the fast growth axis inhibiting normal crystal growth.

Animals↗
PubMed1985

Characterization of lacto-N-hexaose and two fucosylated derivatives from human milk by high-performance liquid chromatography and proton NMR spectroscopy.

The branched hexasaccharide whose trivial name is lacto-N-hexaose (LNH) as well as a mono- and a difuco-derivative were isolated from human breast milk of a Lewis a positive donor by high-performance liquid chromatography (HPLC). Reversed-phase HPLC on C18 columns which have been used previously in our laboratory for successful separations of the smaller milk oligosaccharides were not effective in this system. However, normal-phase HPLC on an amino-bonded silica column (Varian AX-5) gave both analytical and preparative separations. The identity of the LNH core structure was verified both by HPLC and by NMR spectroscopy of the fucosidase digestion products of the fucosylated oligosaccharides. LNH was identified by NMR spectroscopy of the reduced and acetylated derivative whose high field spectrum has been previously reported. The positions of fucosylation of beta-GlcNAc residues were determined by the characteristic chemical shifts of the resonances assigned to alpha-fucose H1 and H5. The assignment of many of the resonances to sugar ring protons was possible using difference decoupling methods. The observation of nuclear Overhauser effects between the anomeric protons and the aglycone protons of adjacent residues confirmed the assignment of the glycosidic linkages.

Chromatography, High Pressure Liquid↗
PubMed1985

Prolonged electrical systole and QT greater than QS2 secondary to coronary artery disease.

Dyssynchronous depolarization-repolarization in the left ventricular (LV) myocardium may produce QT greater than QS2 or long QT. In 41 patients with coronary artery disease (CAD) and LV aneurysm, 46 patients with CAD and a history of acute myocardial infarction (AMI) but no LV aneurysm, and 52 patients with CAD without previous AMI, QT and QS2 were measured simultaneously at a speed of 100 mm/s within 48 hours of cardiac catheterization. Patients receiving class I antiarrhythmic drugs were excluded. The incidence of QT greater than QS2 was significantly greater in patients with LV aneurysm (71%) than in those with previous AMI (22%) and those with CAD but no previous AMI (20%) (p less than 0.001). Likewise, the incidence of long QT corrected for heart rate was significantly greater in patients with LV aneurysm (54%) than in those with previous AMI (7%) and those with CAD and no previous AMI (6%) (p less than 0.0001). The incidence of QT greater than QS2 in another 19 patients with previous AMI who were receiving digitalis therapy was significantly greater (65%) than in those with previous AMI but not receiving digitalis therapy (22%) (p less than 0.001). The incidence of long QT corrected for heart rate and QT greater than QS2 was not statistically different between patients with previous AMI and those with CAD but no previous AMI. The QT greater than QS2 or long QT in patients with aneurysm is probably a result of dyssynchronous depolarization or repolarization within or in the border zone of the LV aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Carbon nuclear magnetic resonance spectra of oligosaccharides isolated from human milk and ovarian cyst mucin.

Natural abundance Carbon-13 nuclear magnetic resonance spectra at 20 MHz were reported for the three common human milk oligosaccharides, lacto-N-tetraose and lacto-N-fucopentaoses I and II, as well as for two related tetra- and hexasaccharide alditols isolated from the alkaline borohydride degradation products of an ovarian cyst glycoprotein. Spectral assignments made with the help of deuterium-induced shift (DIS), attached proton test (APT), and T1 data indicated some very irregular glycosylation shifts which were attributed to effects of steric crowding and non-nearest-neighbor interactions. Samples as small as 10 mumol of oligosaccharide gave acceptable 20-MHz spectra with the use of a 5-mm probe coil.

Carbon Isotopes↗
PubMed1985

Failure of percutaneous transluminal coronary angioplasty to stimulate platelet and prostaglandin activity.

Platelet function and prostaglandin activity were evaluated in nine patients with coronary artery disease undergoing percutaneous left anterior descending coronary artery angioplasty (PTCA) and compared to nine normal controls. Transcoronary measurements (arterial-coronary sinus) of platelet counts, mean platelet volume, platelet factor 4 (PF4), beta thromboglobulin, thromboxane (B2), and 6-keto-PGF 1 alpha were made. When compared to normal controls, the patients with coronary artery disease had higher circulating baseline levels of PF4 in the coronary sinus. There was no transcardiac production of any factor at baseline or immediately after infusion of nitroglycerin or performance of PTCA. These results suggest that PTCA does not grossly alter arachidonic acid metabolism or platelet activity.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

The combination of normal-phase and reverse-phase high-pressure liquid chromatography with NMR for the isolation and characterization of oligosaccharide alditols from ovarian cyst mucins.

Normal-phase high-pressure liquid chromatography (HPLC) on amino-bonded silica with elution by aqueous acetonitrile is shown to be an especially suitable complement to reverse-phase HPLC on octadecyl silica for the fractionation of oligosaccharide alditols produced by alkaline borohydride degradation of mucin glycoproteins. The former technique separates well on the basis of molecular size, while the latter method shows selectivity for stereoisomers. Stereoisomeric pairs of tetra-, penta- and hexasaccharide alditols show relative retention times ranging from 3 to 12, resulting in excellent preparative separations in reverse-phase chromatography. From a single ovarian cyst glycoprotein, H and Lewis b active, 13 oligosaccharides, representing essentially the entire carbohydrate content, have been isolated. The structures of 12 of the oligosaccharides have been determined by 1H-NMR spectroscopy. For those oligosaccharides which have been isolated from other sources and whose NMR spectra have been previously reported, unambiguous structural identification follows directly. Structures of oligosaccharides differing by only one or two residues from those whose NMR spectra are known may be deduced by a simple algorithm utilizing chemical shift analogies.

Chromatography, High Pressure Liquid↗
PubMed1984

Conformation of the antifreeze glycoprotein of polar fish.

High-field proton and 13C NMR spectroscopy has been used to test and refine the recent proposal, based on vacuum uv circular dichroism results, of a threefold left-handed helical conformation for antifreeze glycoprotein (AFGP). Partial assignment of the protons of the glycotripeptide repeating unit has been made by comparison with spectra of model compounds, by selective decoupling, and by measurements of nuclear Overhauser effect (nOe). At 40 degrees C, AFGP fraction 8 (Mr 2600) shows 2-Hz linewidths which broaden at lower temperature. Neither 1H nor 13C chemical shifts depend strongly on temperature, suggesting no abrupt conformational transition. The nOe between alanine alpha and beta protons vary with temperature and with field strength, from small positive enhancements at 50 degrees C and 80 MHz to large negative effects at 3 degrees C and 300 MHz, indicating a substantial change of rotational correlation time with temperature. The higher-molecular-weight fraction 1-4 shows negative nOe at all temperatures. The CD spectra of fraction 1-4 show bands characteristic of the polyproline II structure at both 3 and 50 degrees C, while those bands in fraction 8 are weaker at 50 than 3 degrees C. The 1H nOe, the 13C T1, and CD data are interpreted as indicating that AFGP fraction 8 is an extended "rod-like" conformation at low temperature which becomes a flexible coil at high temperature, while fraction 1-4 is a flexible rod with sufficient segmental mobility to eliminate any long-range order.

Animals↗
PubMed1984

Resolution of some glycopeptides of hen ovalbumin by reverse-phase high-pressure liquid chromatography.

Reverse-phase high-pressure liquid chromatography has been shown to be useful in fractionation of oligosaccharides containing N-acetyl amino sugars on the basis of stereochemical differences. Data in this paper show this same stereochemical selectivity can be obtained for glycopeptides. Using dilute aqueous phosphate for elution, three major high-mannose glycopeptides from ovalbumin can be separated on the analytical scale in a few minutes and the same method can also be used for preparation of the glycopeptides on the milligram scale. High-field proton NMR spectroscopy is used to identify two of the compounds as the mannose-5 and -6 glycopeptides (E3 and D3) and the third as the mannose-6 glycopeptide substituted by two N-acetyl glucosamine (GlcNAc) residues (C3B). The NMR spectra and analytical chromatograms of the glycopeptides show high purity and freedom from contaminants previously identified in ovalbumin glycopeptides.

Animals↗
PubMed1984

The noninvasive localization of ventricular pacing sites by radionuclide phase imaging.

This study was designed to investigate the potential role of radionuclide angiographic phase imaging in defining ventricular pacing sites. Twenty patients were paced from multiple right ventricular and left ventricular sites. Ten patients had both normal wall motion and normal electrocardiograms (ECGs), while 10 patients had segmental wall motion abnormalities and/or bundle branch block. Both continuous pacing and premature ventricular stimuli were performed. Multiple (two to three) views of each pacing site were obtained by radionuclide angiography and the ventricular site was determined by subsequent phase imaging. Simultaneous 12-lead ECGs were also obtained. The phase-imaging technique accurately localized all 35 right ventricular and 21 of 25 (84%) left ventricular sites to a specific segment. Statistically, this localization ability was independent of baseline wall motion or conduction system disease. In addition, sites as close as 1.5 cm were identified. The 12-lead ECG distinguished left ventricular from right ventricular pacing sites in all patients. Segmental localization by ECG in the right ventricle was accurate in 24 of 35 (69%) and in the left ventricle in 17 of 25 (68%). Thus, radionuclide angiographic phase imaging provides excellent descriptive information regarding the focus of ventricular pacing ectopy and can define both sites of continuous pacing and intermittent premature ventricular stimulation. These findings provide a basis for further assessment of the role of phase imaging in the evaluation of patients with spontaneous ventricular ectopy.

Bundle-Branch Block↗
PubMed1983

Mitral valve prolapse syndrome: analysis of 62 patients aged 60 years and older.

Sixty-two patients diagnosed as having mitral valve prolapse, 60 to 81 years old, presented with disabling chest pain (20), symptoms of arrhythmias including palpitations and syncope (16), or mitral regurgitation (MR) with symptoms of congestive heart failure (26). The diagnosis of MVP was made on the basis of a combination of classic auscultatory, echocardiographic and angiographic findings. Thirteen of the 20 patients with chest pain had normal coronary angiograms and 7 had significant coronary artery disease (CAD). Patients with CAD could not be differentiated by clinical presentation alone. Furthermore, the incidence and types of arrhythmias, the presence of a positive stress test, and hemodynamic findings were similar in all patients in this group whether or not CAD was present. The 16 patients with palpitations had a broad spectrum of rhythm disorders, including both supraventricular and ventricular arrhythmias. Two patients had prehospital "sudden death" and 2 others had systemic emboli. Twenty-one of the 26 patients with MR had valve surgery. Intraoperatively the valves were described as enlarged, floppy and with redundant leaflets. Histologic examination showed extensive "myxomatous" changes throughout the valve leaflets. Thus, mitral valve prolapse is a cause of symptomatic heart disease in the elderly. It has a predictable pattern of clinical presentation and should be considered in the differential diagnosis of older patients with disabling chest pain and arrhythmias and as the cause of progressive or severe MR.

Aged↗