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Biomedical subjects

C A Bush

Publications and source records attributed to C A Bush.

At least 109 records · Page 6Linked to original sources
PubMed1980

Comparison of resting intracoronary particulate imaging and stress thallium-201 studies.

Stress thallium-201 and resting dual intracoronary particulate imaging were evaluated in 120 patients who underwent coronary angiography. Forty of 42 patients without significant coronary disease had normal stress images and 41 had normal rest studies. Eighty-three stress perfusion defects were identified in 61 of 78 patients with coronary artery disease. At rest, 39 of these defects were resolved or improved, whereas 44 remained unchanged. The angiographic presence of collateral vessels and radionuclide evidence of blood flow distribution through them could not always be correlated as 36 angiographic collateral vessels had no regional distribution flow patterns with either method. Particulate studies demonstrated myocardial flow distribution through 25 angiographic collateral vessels and further identified seven collateralized areas not seen angiographically. The resting particulate images additionally defined flow distribution patterns in 15 instances in which the angiogram indicated two potential sources of blood supply.

Collateral Circulation↗
PubMed1980

Myocardial perfusion as an indicator of graft patency after coronary artery bypass surgery.

Stress and resting myocardial perfusion were assessed in 38 patients who received 96 grafts. Stress perfusion was evaluated with thallium-201 and resting myocardial blood flow distribution with radiolabeled particles. When both stress and rest perfusion were normal, graft patency was 82% (51 of 62 grafts). Graft patency was also high (81%, 13 of 16) in areas where stress perfusion abnormalities resolved or become less apparent at rest. However, when stress perfusion defects remained unchanged at rest, the graft was likely to be occluded (73%, 11 of 15). Maintenance of normal rest perfusion or improvement of rest perfusion postoperatively was also associated with a high graft patency rate (80%, 35 of 44), whereas the development of new rest perfusion defects postoperatively implied graft occlusion (86%, six of seven).

Coronary Artery Bypass↗
PubMed1980

Corticosteroids in acute myocardial infarction.

Forty-two patients admitted to the Coronary Care Unit with a diagnosis of acute myocardial infarction were studied within 24 hours of the onset of symptoms. In addition to therapy determined by the attending physician, there was a double-blinded administration of either a placebo or methylprednisolone, 30 mg/kg intravenously every 6 hours for four doses. This drug had no beneficial effect on infarct size, dysrhythmias, complications, or left ventricular function 2 weeks after infarction.

Creatine Kinase↗
PubMed1980

Extensive myocardial blood flow distribution through individual coronary artery bypass grafts.

The regional myocardial perfusion distribution of coronary artery bypass grafts were studied in 61 patients who received 162 grafts. Selective intragraft instillations of radioactive-labeled macroaggregated albumin particles were used to study perfusion. The extent of individual graft perfusion was assessed in 100 patent grafts. Regional myocardial blood flow distribution was similar to the blood flow distribution of the native vessel receiving the graft in 64 of 100 grafts and less than that expected of the native vessel in 12 grafts. However, 24 grafts demonstrated a blood flow distribution pattern which extended beyond the normal distribution expected of the native vessel receiving the graft. This extensive perfusion could be attributed to collateral vessels or retrograde flow. A high incidence of both graft and native vessel occlusion was found in areas receiving blood from these distant grafts with extensive distributions (16/24), and left ventricular wall motion was preserved or significantly improved postoperatively in 28/31 segments in such areas. When comparing angiographic and scintigraphic methods of evaluating myocardial perfusion, the angiogram underestimated the full extent of graft blood flow distribution in 13 of 24 instances (54 percent).

Coronary Angiography↗
PubMed1979

Gas chromatography and mass spectrometry of disaccharides from glycoproteins.

Partial acid hydrolysis and methanolysis released disaccharides and disaccharide methylglycosides from the glycoproteins, ovomucoid and porcine gastric mucin in amounts of 0.5--7 microgram disaccharide per mg of glycoprotein. These disaccharides were fractionated by gas chromatography as the trimethylsilyl (Me3Si) derivatives. The composition of recovered disaccharides has been determined by hydrolysis and rechromatography of the Me3Si monosaccharides. The intersaccharide linkages of the disaccharides have been determined by electron impact mass spectrometry. This simple and rapid method can give structural information on small glycoprotein samples.

Animals↗
PubMed1979

Improvement of myocardial perfusion and left ventricular function after coronary artery bypass grafting in patients with unstable angina.

Changes in myocardial perfusion and left ventricular function were evaluated pre- and post-operatively (3--6 months) in 14 patients with unstable angina who underwent coronary artery bypass surgery. Perfusion was studied with intracoronary and intragraft injections of radiolabeled macroaggregated albumin particles. Of 20 abnormal perfusion areas identified preoperatively, 13 demonstrated improved perfusion post-operatively. Segmental analysis of the left ventriculogram demonstrated improved wall motion in 29 abnormally contracting segments; 18 normalized. Areas which showed improvement of left ventricular perfusion were invariably associated with improvement of left ventricular wall motion. Five patients showed improvement in perfusion and contraction in areas of apparent old myocardial infarction. Thirteen of the 14 patients had significantly less angina whether or not there was evidence of improved perfusion. However, only those patients who demonstrated improved perfusion had a significant improvement in their treadmill exercise tolerance postoperatively. Thus, patients with unstable angina have perfusion defects which may be reversed as a result of saphenous vein graft surgery. Reversal of these perfusion abnormalities results in improved left ventricular performance and better exercise tolerance postoperatively.

Angina Pectoris↗
PubMed1978

Circular dichroism of beta turns in peptides and proteins.

Circular dichroism (CD) spectra are reported for two groups of cyclic hexapeptides having beta turns whose geometry can be firmly established by X-ray crystallography and by NMR spectroscopy. One series contains the sequence L-Pro-D-Phe in the geometry of the classical type II beta turn, while the second group has the sequence D-Phe-L-Pro in the closely related geometry of the gramicidin S turn. CD data on the hydrogenated peptides show that in neither series do Cotton effects due to the aromatic phenylalanyl chromophore make a significant contribution to the spectra in the 195--240-nm region. In spite of the close geometric similarity of the beta turns of these two groups of peptides, their CD spectra are quite distinct. Furthermore, comparison of our data with the CD spectra of published models for beta-turn structures suggests that it may not be possible to characterize the contribution of all beta turns to the CD spectra of proteins by a single model curve. the CD spectra of model beta turns will be more useful in characterizing the folding of oligopeptides and sequence polypeptides, where a single type of turn is present.

Circular Dichroism↗
PubMed1978

Comparative systemic and regional hemodynamic effects of dopamine and dobutamine in patients with cardiomyopathic heart failure.

Thirteen patients with severe cardiac failure underwent a single crossover study of dopamine and dobutamine in order to compare the systemic and regional hemodynamic effects of the two drugs. The dose-response data demonstrated that dobutamine (2.5--10 microgram/kg/min) progressively and predictably increases cardiac output by increasing stroke volume, while simultaneously decreasing systemic and pulmonary vascular resistance and pulmonary capillary wedge pressure. There was no change in heart rate or premature ventricular contractions (PVCs)/min at this dose range. Dopamine (2--8 microgram/kg/min) increased the stroke volume and cardiac output at 4 microgram/kg/min. Dopamine at less than 4 microgram/kg/min provided little additional increase in cardiac output and increased the pulmonary wedge pressure and the number of PVCs/min. At greater than 6 microgram/kg/min, dopamine increased heart rate. During the 24-hour maintenance-dose infusion of each drug (dopamine 3.7--4, dobutamine 7.3--7.7 microgram/kg/min), only dobutamine maintained a significant increase of stroke volume, cardiac output, urine flow, urine sodium concentration, creatinine clearance and peripheral blood flow. Renal and hepatic blood flow were not signfiicantly altered by the maintenance dose of either drug. Systemic and regional hemodynamic data suggest that dobutamine has many advantages over dopamine when infused in patients with cardiac failure.

Adult↗
PubMed1978

Systolic time intervals in atrial fibrillation.

Forty patients with atrial fibrillation and 20 patients with congestive heart failure and sinus rhythm were studied. Patients were divided into two groups. Group A consisted of 20 patients with atrial fibrillation in whom systolic time intervals were measured. Twenty to 50 beats were analyzed. Five of the patients had high-fidelity measurements of left ventricular pressure simultaneous with determination of systolic time intervals. Analysis of the systolic time intervals for the entire group showed that the preejection period lengthened at faster heart rates and that the left ventricular ejection time was relatively constant at slower heart rates. This resulted in a progressive increase in the ratio of preejection period over left ventricular ejection time (PEP/LVET) as the heart rate increased. The rate of increase in PEP/LVET was minimal below a heart rate of 75 beats per minute. The increase in preejection period at faster heart rates is due to greater isovolumic developed pressure without a corresponding increase in left ventricular dp/dt. Group B consisted of 40 additional patients (20 with atrial fibrillation and 20 with sinus rhythm). In group B, the total electromechanical systole corrected for heart rate (QS2I) and the levels of digoxin in the blood were compared. The QS2I was significantly shorter in atrial fibrillation (497 +/- 5 msec vs 528 +/- 4 msec; P less than 0.01), while the levels of digoxin in the blood were identical (0.9 +/- 0.1 vs 1.0 +/- 0.1 ng/ml). The results of this study must be considered when systolic time intervals are to be employed in patients with atrial fibrillation.

Adult↗
PubMed1978

Endomyocardial fibrosis with calcification of the myocardium.

A case of endomyocardial fibrosis with intramyocardial calcification was characterized by symptoms of restrictive cardiomyopathy resembling constrictive pericarditis. Pathological findings were typical of those found in classical Davies' disease, originally encountered and described in Uganda.

Calcinosis↗
PubMed1977

Determination of the linkages of disaccharides containing a 2-acetamido-2-deoxy sugar unit by solvent effects in circular dichroism.

The circular dichroism spectra of 2-acetamido-2-deoxy sugars in 1,1,1,3,3,3-hexafluoro-2-propanol (F6Pr-2-ol) solutions show a positive band in the n-pi region (209 nm) in contrast to a negative c.d. band in water solution. This difference is interpreted as an indication of a change in the average orientation of the hydroxyl groups adjacent to the amide group. C.d. spectra of 2-acetamido-2-deoxy sugars having a methyl group at O-1 and O-3 confirm this interpretation and suggest that the c.d. spectrum of a disaccharide in F6Pr-2-ol reflects strongly the disaccharide linkage. Large differences in the c.d. spectra of (1 leads to 4) and (1 leads to 6)-linked disaccharides in this solvent lead to rules for distinguishing the linkages of the disaccharides.

Acetylgalactosamine↗
PubMed1977

The cardiovascular effects of the continuous infusion of dobutamine in patients with severe cardiac failure.

Twenty-five patients with left ventricular failure and low cardiac output received a 72 hour infusion of dobutamine (10-15 microgram/kg/min) in order to determine the cardiovascular properties of this new inotropic agent. Left ventricular contractile performance improved significantly during the infusion as measured by systolic time intervals and echocardiographic parameters. Mean PEP/LVET decreased from 0.76 +/- 0.03 to 0.58 +/- 0.03 (P less than 0.05). The percent change in internal dimension of the left ventricle from diastole to systole increased from 9.5 +/- 1 to 16.8 +/- 1 (P less than 0.05) and Vcf increased from 0.47 +/- 0.05 to 0.80 +/- 0.06 circ/sec (P less than 0.05). Mean cardiac output (nine patients) rose from 1.97 +/- 0.15 to 3.33 +/- 0.50 L/min/m2 while mean pulmonary capillary wedge pressure fell from 28 +/- 3 to 18 +/- 2 mm Hg during the infusion period (both P less than 0.05). These changes in cardiac function occurred without significant changes in heart rate, ventricular irritability, or blood pressure. Urine flow and urine sodium concentration increased during the infusion period. The improvement of cardiac function without the simultaneous development or exacerbation of undesirable effects (tachycardia, premature ventricular contractions, increased pulmonary or systemic resistance, tachyphylaxis, etc.) makes dobutamine a highly desirable inotropic agent.

Adolescent↗
PubMed1977

Occult constrictive pericardial disease. Diagnosis by rapid volume expansion and correction by pericardiectomy.

Significant pericardial disease can exist without overt manifestations. Occult constrictive pericardial disease (OCPD) is identified by normal baseline hemodynamics and normal left ventricular systolic function with a characteristic response to rapid volume infusion. Following the intravenous administration of 1000 ml of normal saline over six to eight minutes, striking elevations of filling pressures are seen; however, diagnosis depends specifically upon a) the development of typical pressure pulse morphology of constriction, b) loss or reversal or respiratory variation of right atrial pressure, and c) precise diastolic equilibration of intracardiac pressures. Nineteen patients with OCPD have been identified in a five year period. Unexplained fatigue, dyspnea and chest pain was the uniform pattern of presentation. Eleven have undergone pericardiectomy resulting in a dramatic symptomatic improvement in all. Each demonstrated gross and/or microscopic evidence of pericardial disease. Recatheterization with volume infusion in five patients following pericardiectomy has revealed return to normal or near normal hemodynamics. This study describes the method for diagnosis of OCPD and recommends pericardiectomy for the management of disabling symptoms.

Adolescent↗
PubMed1975

Circular dichroism of oligosaccharides containing neuraminic acid.

In order to test the usefulness of circular dichroism in stereochemical and structural studies of oligosaccharides of glycoproteins, we measured the circular dichroism (CD) for N-acetylneuraminic acid (NAcNA) and several derivates. By acidic mathanolysis, we have prepared the deacetylated methyl ester, methyl glycoside of NAcNA, as well as a saponified product. Circular dichroism of these compounds allows us to assign the transition due to the amide chromophore. There is a carboxyl n-pi transition at about 220 nm which has a negative CD band associated with it for the beta-methocyneuraminic acid, but changes sign for the methyl ester (methyl (methyl beta-D-neuraminid)ate). We isolated the trisaccharides N-acetylneuraminyl-(2 leads to 3)-beta-D-galactopyranosyl-(1 leads to 4)-D-glucopyranose [(2leads to 3)NAcN-Lac] as well as (2 leads to 6)NAcN-Lac by paper chromatography and compared the CD for each. The two isomers show similar but distinguishable CD patterns, with a weak negative band due to the carboxyl group centered at 225 nm and a stronger positive band at 200 nm containing contributions from both the amide and carboxyl groups.

Chromatography, Gas↗