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Biomedical subjects

D Bogen

Publications and source records attributed to D Bogen.

7 recordsLinked to original sources
PubMed2001

The Batista procedure. Theoretical analysis and clinical implications.

BACKGROUND: The Batista procedure leads to dramatic early improvement in left ventricular function in some patients and a worsening in function in others. The theoretical and actual clinical effects of the procedure on early postoperative left ventricular function remain controversial. The purpose of this study is to utilize an appropriate mathematical model to determine the effects of the Batista procedure on stroke volume and myocardial wall stress. Our hypothesis is that the preoperative end-systolic stress (ses) is an important predictor of early postoperative myocardial function after this procedure. A corollary is that an index related to ses may be useful in selecting patients for this procedure. METHODS: An analysis of the Batista procedure is developed, based upon a spherical membrane model of the ventricle. This model shows how ventricular dilatation distorts the systolic and diastolic pressure-volume relations. RESULTS: Dilatation initially improves ventricular performance; but further dilatation, beyond a critical value, produces an unstable state with sharply falling performance. For a ventricle operating significantly beyond the point of critical dilatation, our theoretical results suggest that the Batista procedure not only reduces myocardial stress but may improve stroke volume. The end-systolic stress, ses is an indicator of how close a ventricle is to the critical dilatation point. CONCLUSIONS: There is a theoretical basis for the Batista procedure. Resection of myocardium not only decreases wall stress but may improve stroke volume for sufficiently dilated and depressed ventricles. Patients with markedly elevated end-systolic stress may benefit most from the Batista procedure.

Cardiac Surgical Procedures↗
PubMed1991

Novel and potent gastrin and brain cholecystokinin antagonists from Streptomyces olivaceus. Taxonomy, fermentation, isolation, chemical conversions, and physico-chemical and biochemical properties.

The discovery and physico-chemical characterization of three novel and minor virginiamycin M1 analogs as potent gastrin antagonists from a culture of a strain of Streptomyces olivaceus are described. These analogs are L-156,586, L-156,587 and L-156,588. They are, respectively, 15-dihydro-13,14-anhydro-, 13,14-anhydro- and 13-desoxy-analogs of virginiamycin M1. We also chemically converted virginiamycin M1 (via L-156,587) to L-156,586 and its unnatural epimer, L-156,906. These analogs are competitive and selective antagonists of gastrin and brain cholecystokinin binding at nanomolar concentrations. These are the most potent gastrin/brain cholecystokinin antagonists from natural products. The same compounds showed poor Gram-positive antibiotic activity versus virginiamycin M1. Structurally related Gram-positive antibiotics, griseoviridin and madumycin I, were inactive in gastrin and brain cholecystokinin binding at up to 100 microM.

Animals↗
PubMed1988

Flow dynamics of peripheral venous catheters during extracorporeal membrane oxygenation with a centrifugal pump.

Extracorporeal membrane oxygenation uses peripherally placed cannulas and a streamlined circuit without a venous reservoir. This study tests the flow dynamics of venous catheters connected without a reservoir directly to a centrifugal pump. During in vitro testing, a 30 cm segment of collapsible tubing interposed between the reservoir and pump simulates the vein. In five sheep, flow was measured between catheters placed in the right atrium and inferior vena cava from peripheral sites. Catheter tip design (four types) does not affect flow within a simulated vein in vitro. Maximum pump flow is independent of filling pressures (6 to 21 mm Hg) in vitro and in vivo when the catheter tip is in a tank reservoir or the right atrium. However, when the catheter tip is within a collapsible segment or in the inferior vena cava, maximal flow is significantly influenced by filling pressure (6 to 18 mm Hg) and by the ratio of catheter outer diameter to venous diameter. At all filling pressures, maximal flow in vivo is significantly reduced when this ratio is greater than 0.5. During extracorporeal membrane oxygenation, central venous pressure and catheter/vein ratio, not catheter size alone, control flow through peripheral venous catheters.

Adult↗
PubMed1978

Regional variations in calculated diastolic wall stress in rat left ventricle.

Principal radii of curvature and wall thickness were measured at the apex and three other loci on the free wall of the left ventricle in 16 rat hearts that had been fixed at end-diastolic pressure. The law of Laplace was applied to calculate the mean tensile stress at each locus. No significant variation was found among the nonapical loci, but apical stress was approximately twice the stress calculated for any nonapical locus. The higher stresses that must be borne by the apex may be a predisposing factor for apical aneurysm in certain cardiomyopathies such as Chagas' disease. These higher stresses may also help to promote apical aneurysms in patients with ischemic heart disease.

Animals↗
PubMed1975

Follow-up of mentally retarded adults successfully and unsuccessfully placed in community group homes.

State hospital staff members compared 72 retarded adult patients who had been successfully placed in group homes in the community with 13 patients who had been placed but rehospitalized. No significant differences were found between the groups on the four variables of sex, age at the time of the study, age at first admission to the hospital, and time spent in the hospital. A comparison of preplacement problems listed in the patients' hospital records with the reasons for rehospitalization of the unsuccessfully placed group suggests that both hospital staff and group home parents find aggressive behaviors a problem, but that group home parents are more concerned than hospital staff with deficiencies in self-care.

Adult↗
PubMedDate not supplied

Nonuniform distribution of normal pericardial fluid.

It has been suggested that pericardial fluid functions as a lubricant rather than a means of transmitting pericardial pressure from one region of the heart to another. Since the functional behavior of pericardial fluid depends on fluid thickness, we measured pericardial volume and fluid distribution. In seven animals, we found that the normal canine pericardium contains 0.25 +/- 0.15 ml of pericardial fluid per kg of body weight, resulting in an average pericardial fluid thickness of only 0.34 +/- 0.27 mm. We next determined the pericardial fluid distribution in eight anesthetized mongrel dogs (17-29 kg). Color video images were recorded, while green dye (0.1 ml) was injected into the pericardial space overlying the ventricular apex to allow visualization of the pericardial fluid distribution. Within 26 +/- 17 s (range 15-53 s), dye reached the base of the heart. After 15 min of equilibration, the dye distribution appeared very nonuniform with dye accumulation over the interventricular and atrioventricular grooves. Little or no dye was present over the right and left ventricular free walls. We conclude that pericardial fluid thickness over the interventricular and atrio-ventricular grooves is sufficient to allow fluid motion in these regions. In contrast, pericardial fluid thickness overlying the ventricular free walls is very thin. Thus, in these regions the pericardial fluid functions primarily as a lubricant; and regional variations in pericardial pressure may occur.

Animals↗