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Biomedical subjects

J Burge

Publications and source records attributed to J Burge.

14 recordsLinked to original sources
PubMed1986

Safety and efficacy of flestolol, a new ultrashort-acting beta-adrenergic blocking agent, for supraventricular tachyarrhythmias.

Flestolol, a new ultrashort-acting (half-life 6.9 minutes) beta-blocking drug, was administered by intravenous infusion to 18 patients with new-onset atrial fibrillation or flutter and rapid ventricular response (120 beats/min or more for at least 30 minutes). Drug dose of flestolol was progressively increased until at least 1 of 3 endpoints was achieved: at least a 20% reduction in heart rate from baseline, heart rate 100 beats/min or less, or conversion to normal sinus rhythm. Flestolol was then administered as a maintenance infusion up to 24 hours. When flestolol was discontinued, patients were monitored for 1 additional hour. The mean ventricular response at baseline of 133 +/- 12 beats/min decreased to 103 +/- 20 beats/min at the end of flestolol titration (p less than 0.0001). Fourteen patients (78%) achieved defined endpoints. All 14 patients who continued to receive maintenance infusion had a sustained response. When flestolol was discontinued, ventricular response increased 33 +/- 23% within 60 minutes. The only adverse effect seen was hypotension in 2 patients. Flestolol is effective in slowing ventricular response in new-onset atrial fibrillation and flutter, maintains a therapeutic effect during continuous infusion and rapidly loses therapeutic effect when discontinued.

Adrenergic beta-Antagonists↗
PubMed1986

Flestolol: an ultra-short-acting beta-adrenergic blocking agent.

Flestolol (ACC-9089) is a nonselective, competitive, ultra-short-acting beta-adrenergic blocking agent, without any intrinsic sympathomimetic activity. Flestolol is metabolized by plasma esterases and has an elimination half-life of approximately 6.5 minutes. This agent was well tolerated in healthy volunteers at doses up to 100 micrograms/kg/min. In long-term infusion studies, flestolol was well tolerated at the effective beta-blocking dose (5 micrograms/kg/min) for up to seven days. Flestolol blood concentrations increased linearly with increasing dose and good correlation exists between blood concentrations of flestolol and beta-adrenergic blockade. Flestolol produced a dose-dependent attenuation of isoproterenol-induced tachycardia. Electrophysiologic and hemodynamic effects of flestolol are similar to those of other beta blockers. In contrast with other beta blockers, flestolol-induced effects reverse rapidly (within 30 minutes) following discontinuation because of its short half-life. Flestolol effectively reduced heart rate in patients with supraventricular tachyarrhythmia. In patients with unstable angina, flestolol infusion was found to be safe and effective in controlling chest pain. It is concluded that flestolol is a potent, well-tolerated, ultra-short-acting beta-adrenergic blocking agent. Use of flestolol in the critical care setting is currently undergoing investigation.

Adrenergic beta-Antagonists↗
PubMed1986

Tolerance and beta-adrenergic blocking activity of flestolol, a short-acting beta blocker.

The tolerance and beta-adrenergic blocking activity of flestolol, a short-acting beta-blocker, was investigated in 30 subjects. Flestolol infused intravenously at doses up to 100 micrograms/kg/min was found to be well tolerated. A dose-dependent attenuation of isoproterenol-induced tachycardia and increase in systolic blood pressure occurred with flestolol at doses ranging from 0.5 to 15.0 micrograms/kg/min. The average percent reduction in isoproterenol-induced tachycardia (beta-blockade) at each dose of flestolol, 0.5, 2.5, 5.0, 15.0, and 50.0 micrograms/kg/min, was 15.1%, 45.9%, 67.0%, 85.9%, and 90.3%, respectively. The onset of beta-blockade occurred within 30 minutes. After the end of flestolol infusion there was a marked reduction in beta-blockade within 6 minutes, with complete recovery from beta-blockade within 30 to 45 minutes. There was a statistically significant (P less than 0.01) positive correlation between flestolol dosage and its blood levels (r = 0.91) as well as between the flestolol-induced beta-blockade and its dosage (r = 0.62).

Adult↗
PubMed1985

Dynamics of interaction between complement-fixing antibody/dsDNA immune complexes and erythrocytes. In vitro studies and potential general applications to clinical immune complex testing.

Soluble antibody/3H-double-stranded PM2 DNA (dsDNA) immune complexes were briefly opsonized with complement and then allowed to bind to human erythrocytes (via complement receptors). The cells were washed and subsequently a volume of autologous blood in a variety of media was added, and the release of the bound immune complexes from the erythrocytes was studied as a function of temperature and time. After 1-2 h, the majority of the bound immune complexes were not released into the serum during blood clotting at either 37 degrees C or room temperature, but there was a considerably greater release of the immune complexes into the plasma of blood that was anticoagulated with EDTA. Similar results were obtained using various conditions of opsonization and also using complexes that contained lower molecular weight dsDNA. Thus, the kinetics of release of these antibody/dsDNA immune complexes differed substantially from the kinetics of release of antibody/bovine serum albumin complexes that was reported by others. Studies using the solution phase C1q immune complex binding assay confirmed that in approximately half of the SLE samples that were positive for immune complexes, there was a significantly higher level of detectable immune complexes in plasma vs. serum. Freshly drawn erythrocytes from some SLE patients exhibiting this plasma/serum discrepancy had IgG antigen on their surface that was released by incubation in EDTA plasma. Thus, the higher levels of immune complexes observed in EDTA plasma vs. serum using the C1q assay may often reflect the existence of immune complexes circulating in vivo bound to erythrocytes.

Antigen-Antibody Complex↗
PubMed1984

Suramin inhibits the binding of complement-fixing antibody/double-stranded DNA immune complexes to CR1.

The effects of varying concentrations of heparin and suramin on the complement-mediated binding of antibody/double-stranded DNA immune complexes to red blood cells (RBCs) and Raji cells have been investigated. If the immune complexes are briefly opsonized with complement, suramin can block binding to both cell types, and heparin can block binding to RBCs. In addition, if these complexes are first allowed to bind to RBCs or Raji cells, relatively brief incubations in suramin are sufficient to cause release of the complexes from the cells' C3b receptors. The potential clinical and diagnostic implications of these findings are discussed.

Antibodies↗
PubMed1984

The kinetics of [3H]-dsDNA/anti-DNA immune complex formation, binding by red blood cells, and release into serum: effect of DNA molecular weight and conditions of antibody excess.

[3H]dsDNA/anti-DNA immune complexes (IC) formed, fixed complement, and bound rapidly to red blood cells (RBC) in whole blood (less than 5 min), but were released from the cells more slowly. The rate of release was dependent on both the antibody:DNA ratio and the m.w. of the DNA in the complex. For example, complexes formed with high m.w. DNA (6 X 10(6) daltons) were released more slowly (t1/2 = 60 min) than complexes formed with lower m.w. DNA (2 to 6 X 10(5) daltons, t1/2 = 15 to 20 min). The [3H]dsDNA/anti-DNA complexes, which were released from the cells as intact antigen/antibody/complement complexes, did not rebind to RBC, but did bind to Raji cells and could be precipitated by monoclonal antibody to C3d. When these released IC (RIC) containing high m.w. DNA were incubated with additional anti-DNA antibody and fresh complement, they rebound to RBC. However, RIC containing lower m.w. DNA (5 X 10(5) daltons) did not rebind to RBC under the same conditions. These data suggest that IC containing high m.w. DNA bind to and remain bound to RBC more effectively than IC containing lower m.w. DNA, and thus may be more easily cleared from the circulation by the RBC IC clearance mechanism. Thus, the size of the DNA in the IC may be a significant factor in the pathogenicity of DNA/anti-DNA complexes in SLE.

Antibodies, Antinuclear↗
PubMed1983

The complement-mediated binding of soluble antibody/dsDNA immune complexes to human neutrophils.

The complement-mediated binding of soluble antibody/3H-dsDNA immune complexes (prepared in vitro) to human polymorphonuclear leukocytes (PMN) has been investigated quantitatively. Studies with isolated complement components in conjunction with experiments on the binding of these complexes to human red blood cells suggest that the binding to both cell types is mediated predominantly by CR1 (C4b-C3b) receptors but that CR3 (iC3b or C3d-g) receptors may play a role in binding to PMN but probably not to RBC. Our results also indicate that under the standard conditions of these assays (37 degrees C, 20 to 40 min incubations) there is no significant internalization of the soluble antibody/dsDNA immune complexes after they are bound by the PMN.

Antigen-Antibody Complex↗
PubMed1981

Isolation of C4-binding protein from guinea pig plasma and demonstration of its function as a control protein of the classical complement pathway C3 convertase.

A decay-accelerating factor of the classical complement pathway C3 convertase, C4b,2a, has been purified to homogeneity from guinea pig plasma by a 5-step procedure that includes 5% polyethyleneglycol-4000 (PEG-4000) precipitation, Sepharose 6B gel filtration, heparin-Sepharose chromatography, DE-52 anion exchange chromatography, and Sepharose-C4gp affinity chromatography. The protein elicited a monospecific antiserum in a rabbit and was found with the Mancini technique in both normal and C4-deficient guinea pig plasma at a concentration of 60 microgram/ml. The purified protein gave a single stained band of 550,000 m.w. on SDS-PAGE under nonreducing conditions and a single band of 72,000 m.w. with reduction and alkylation. On the basis of its m.w. and subunit structure, ability to bind to a C4 affinity column, and ability to regulate the classical C system by accelerating the decay of the classical C3 convertase this protein represents the guinea pig analog of the human C4-binding protein.

Animals↗
PubMed1981

Purification from guinea pig erythrocyte stroma of a decay-accelerating factor for the classical c3 convertase, C4b,2a.

A protein with decay-accelerating activity for the classical C3 convertase, C4b2a, has been isolated on the basis of this function from guinea pig erythrocyte stroma. The isolation procedure for decay-accelerating factor of stroma (DAF-S) utilizes butanol extraction and chromatography on DEAE-Sephacel, hydroxylapatite, and phenyl Sepharose. Purified DAF-S has a m.w. of 60,000 and 65,000 on reduced and unreduced SDS gels, respectively, and exhibits m.w. of 30,000 and 175,000 on alkaline gradient gels, suggesting multiples of a 60,000-65,000 subunit. Purified DAF-S elicited a monospecific antiserum whose IgG fraction neutralized the decay-accelerating activity for C4b,2a affixed to 10(7) sheep erythrocytes (EAC1,4,2) in a dose-response fashion. The monospecific antiserum diluted up to 1:5120 agglutinated 1 x 10(6) guinea pig erythrocytes, but not sheep or human erythrocytes, suggesting that DAF-S, an integral membrane protein, has species-specific antigens that are expressed on the surface of the guinea pig erythrocyte.

Animals↗
PubMedDate not supplied

The effect of catheter type and site on infection rates in total parenteral nutrition patients.

Infections pose a major problem in patients receiving total parenteral nutrition. Controversy continues concerning the effect of catheter type (triple-, double-, single-lumen, or pulmonary artery), insertion site (subclavian, internal jugular, or femoral vein), and the incidence of catheter-related infections. We retrospectively studied multi-lumen catheter use for total parenteral nutrition over a 6-month period in 192 patients, a total of 3334 catheter days. Nonintensive care unit catheters were inserted by the Nutrition Support Service, and intensive care unit catheters were inserted by the intensive care unit staff. All catheters were cared for using Nutrition Support Service protocols, with multi-lumen catheters changed every 7 to 10 days and pulmonary artery catheters changed every 4 days. Infections were determined by semiquantitative cultures (> 15 colonies/plate). The incidence of infections for triple-lumen catheters was 5 (subclavian), 17 (internal jugular), and 36% (femoral) respectively; total infection rate for triple-lumen catheters was 10%. Infection rates for pulmonary artery catheters were 4 (subclavian), and 6% internal (jugular site), respectively, the overall infection rate was 5%. There were no differences in infection rates at any site based on catheter type; however, when triple-lumen catheter sites were compared, the differences were significant (p < .001 vs subclavian, chi 2). Catheter duration was 7.8 days (subclavian),, 7.3 days (internal jugular), and 4.6 (femoral) days. These data suggest that the use of multi-lumen catheters for total parenteral nutrition is safe, that there is a benefit associated with the subclavian route, and that the femoral site should be avoided.

Catheterization↗