Binding of cardiolipin to polystyrene beads: evidence for a lamellar phase orientation

Summary. The association of cardiolipin with polystyrene beads was studied using ³¹P-NMR and electron microscopy. In the presence and absence of fetal calf serum, cardiolipin appeared to bind to the polystyrene beads in lamellar phase as assessed by ³¹P-NMR imaging. Electron microscopic analysis revealed an even coating of phospholipid about the beads with extensive micelle binding. Cardiolipin-coated beads challenged with ACA-positive sera followed by immunogold indicated antibody bound to micelles associated with the bead. Studies conducted with ACA IgG purified from patient sera indicated that some ACA bound to CL beads in the absence of a source of ACA cofactor (i.e. gelatin-blocked beads), some ACA required β₂-GPI for binding (i.e. no binding in the presence of β₂-GPI-depleted plasma), whereas other ACA which showed negliglible binding with gelatin-blocked beads, showed enhanced binding in the presence of /?₂-GPI-depleted plasma. The data indicate that: (1) cardiolipin binds to polystyrene beads in lamellar phase, (2) ACA bind to phospholipid micelles bound directly to the polystyrene beads, and (3) ACA differ between individuals displaying varying phospholipid and phospholipid/cofactor substrate specificities.     

Contractile Responses and Structure of Small Bronchi Isolated from Rats after 20 Months' Exposure to Ozone

Short-term exposure to high concentrations of ozone has beenshown to increase airway responsiveness in normal humans andin all laboratory animal species studied to date. While ourknowledge concerning the pulmonary effects of single exposuresto ozone has increased rapidly over recent years, the effectsof repeated exposures are less understood. The goal of the presentstudy was to determine whether airway responsiveness is increasedafter near-lifetime exposure to ozone. Airway segments representingapproximately eighth generation airways were isolated from Fischer344 rats of both genders that had been exposed for 6 hr perday, 5 days per week for 20 months to 0, 0.12, 0.5, or 1.0 partsper million (ppm) ozone. Circtimferential tension developmentwas measured in isolated airways in response to bethanechol,acetylcholine, and electrical field stimulation. Responsivenessof the airways to the contractile stimuli was described by theeffective dose or frequency that elicited half-maximum contraction(ED50) and the maximum response. Since ozone exposure is associatedwith remodeling of peripheral airways, smooth muscle area wasdetermined and tension responses were normalized to the areameasurements. Before normalization of tension data to smoothmuscle area, neither the ED50 nor maximum response of smallbronchi to the contractile stimuli was altered after chronicozone exposure. Smooth muscle area was greater in airways isolatedfrom animals that had been exposed to 0.5 ppm ozone. After accountingfor smooth muscle area, maximum responses of the small bronchiisolated from male rats were significantly reduced after 0.12and 0.5 ppm ozone. Although not significant statistically, asimilar trend was observed in airways isolated from female rats.These results suggest that the increase in airway responsivenessassociated with acute ozone exposure does not persist duringnear-lifetime exposure. Although the mechanism responsible forthe adaptation to the effects of 03 on airway responsivenessis unknown, the results indicate that smooth muscle cell functionwas compromised by the chronic exposure. The mechanism(s) responsiblefor mediating this effect and the relevance of these resultsto humans remains to be determined.     

Effects of Procainamide and Lidocaine on Defibrillation Energy Requirements in Patients Receiving Implantable Cardioverter Defibrillator Devices

Effects of Procainamide and Lidocaine on Defibrillation. intntduction: In acute canine studies, lidocaine. but not prucainamidc, increases defibrillation energy requirements. We evaluated the effects of lidocaine or procainamide on defihrillation energy requirements in 27 patients undergoing intraoperative testing fur implantable cardioverter dcfibrillator device placement.
Methods and Results: Patients were tested off antiarrhythmic drugs and again following either lidocaine (200 to 250 mg loading and 3 mg/min maintenance infusions) or procainamide (1 gm loading and 3 to 4 mg/min maintenance infusions). The defibrillation testing protocol consisted of initial testing at 15 J, followed by higher or lower energies to determine the lowest energy producing three consecutive successful defibrillations. Overall, the mean defibrillation energy increased from 14 ± 5 J to 18 ± 7 J during lidocaine (plasma concentration 5.1 ± 1.6 μ/mL; P < 0.02) but were similar at baseline (12 ± 5 J) and during procainamide infusion (13 ± 6 J) (plasma concentration: procainamide 10.7 ± 7.2 μ/rnl.; N-acetyl procainamide 1.0 ± 0.4 μ/niL). A positive linear correlation was found between lidocaine plasma concentration and percent change in defibrillation energy (lidocaine: r = 0.61; P = 0.01). Procainamide raised the defibrillation energy in three patients, two with supra therapeutic plasma concentrations. The increase in defibrillation energy equaled or exceeded 25 J in four patients after lidocaine and in one patient after procainamide.
Conclusion: The data suggest that at high plasma concentrations, lidocaine and procainamide adversely affect defibrillation energy requirements consistent with an adverse, concentration-dependent effect of sodium channel blockade on defibrillation energy requirements in patients.     

POLYMYALGIA RHEUMATICA IS ASSOCIATED WITH BOTH HLA-DRB1*0401 and DRBl*0404

The frequency of HLA-DRB1 alleles was determined in 68 Caucasoidpatients with polymyalgia rheumatica (PMR) and 140 controlsusing polymerase chain reaction (PCR) sequence-specific oligonucleotidetyping. In keeping with previous studies, an increased frequencyof DRB1^*04 was observed in patients [55.9% vs 35.0%, odds ratio(OR) 2.4, 95% confidence interval (CI) 1.3–4.4]. HLA-DRBl^*0101frequency was also increased in patients, although less confidencecould be placed on this association (19.1% vs 14.3%, OR 1.4,95%CI 0.6–3.3). HLA-DRB1^*O4 subtyping indicated that thefrequencies of both DRB1^*0401 (38.2% vs 22.1%, OR 2.2, 95% CI1.0–4.3) and DRB1^*0404 (16.2% vs 5.0%, OR 3.7, 95% CI1.2–11.1) were specifically raised. An increased frequencyof the RA shared epitope (QKRAA/QRRAA) was also observed inthis group (75.0% vs 44.2%, OR 3.8, 95% CI 1.9–7.6). Whenthe analysis was restricted to only DRB1^*04-negative patientsand controls, the frequencies of DRB1^*0301, ^*11 and ^*08 weremarginally raised. However, no obvious relationship appearedto exist between PMR susceptibility and DRB1 alleles carryingthe DYF conserved epitope in the second hypervariable region.Autoantibodies to thyroid antigens were present in 23% of patients.An increased frequency of DRBl^*0301 was observed in patientswith thyroid microsomal antibodies compared to those without(54.5% vs 24.6%, OR 3.7, 95% CI 0.8–17.0). This increasewas not observed in patients with thyroglobulin autoantibodies.These data indicate that both DRB 1^*0401 and ^*0404 are associatedwith PMR, and that this may extend to include DRB1^*0101. Theimmunogenetic profile of susceptibility markers in this conditionappears to be similar to that in rheumatoid arthritis. KEY WORDS: Polymyalgia rheumatica, HLA-DR4, Thyroid antibodies     

Passage of radioactive erythrocytes from the peritoneal cavity into the blood stream during experimental ascites

Intraperitoneal injection of red cells tagged with radioiron into dogs with experimental ascites demonstrated that such cells were rapidly transferred into the circulating blood. When the experimental animals were not actively producing ascitic fluid, 43.4, 67.0, and 56.4 per cent respectively, of the administered radioactive red cells passed to the blood in 72 hours. In the same three dogs during active ascitic fluid formation, 25.9, 51.2, and 38.8 per cent of the administered radioactivity was removed in a similar period. The amount of radioactivity in the blood stream, consequent on the passage of red cells from the peritoneal cavity into the circulation, becomes nearly constant in 48 hours, whereas for radioactive plasma proteins the plateau is attained in 24 hours (Fig. 1). In normal dogs (16), the passage of red cells from the peritoneal cavity was complete in 72 hours, while in ascitic dogs, 5 to 47 per cent of the injected tagged red cells remained behind in the peritoneum after the same period.