Serum complement activation on heterologous platelets is associated with arterial thrombosis in patients with systemic lupus erythematosus and antiphospholipid antibodies.

Complement plays a major role in inflammation and thrombosis associated with systemic lupus erythematosus (SLE) and the antiphospholipid syndrome (APS). A cross-sectional retrospective analysis was performed to evaluate serum complement fixation on platelets and thrombotic incidence using banked sera and clinical data from patients with SLE (n = 91), SLE with antiphospholipid antibodies (aPL) or APS (n = 78) and primary aPL (n = 57) or APS (n = 96). In-situ complement fixation was measured as C1q and C4d deposition on heterologous platelets using an enzyme-linked immunosorbent assay approach. Platelet activation by patient serum in the fluid phase was assessed via serotonin release assay. Enhanced in-situ complement fixation was associated with the presence of IgG aPL and IgG anti-beta2 glycoprotein 1 antibodies (P < 0.05) and increased platelet activation (P < 0.005). Moreover, enhanced complement fixation, especially C4d deposition on heterologous platelets, was positively associated with arterial thrombotic events in patients with SLE and aPL (P = 0.039). Sera from patients with aPL possess an enhanced capacity for in-situ complement fixation on platelets. This capacity may influence arterial thrombosis risk in patients with SLE.

Anti-heparin platelet factor 4 antibodies in systemic lupus erythematosus are associated with IgM antiphospholipid antibodies and the antiphospholipid syndrome.

OBJECTIVE: To investigate the prevalence and clinical correlates of anti-heparin platelet factor 4 antibodies (anti-HPF4) in systemic lupus erythematosus (SLE) patients with and without antiphospholipid antibodies (aPL). METHODS: Sera and clinical data were obtained from the Hospital for Special Surgery Autoimmune Disease Registry for 78 aPL-positive and 91 aPL-negative SLE patients without heparin-induced thrombocytopenia (HIT). Controls were 90 blood donors of comparable age and sex. Sera were assayed for anti-HPF4, IgG/IgM antiphospholipid antibodies (APhL), and IgG/IgM anti-beta2-glycoprotein 1 antibodies (anti-beta 2GP1). Serotonin release assays (SRAs) were performed for subjects with positive anti-HPF4. RESULTS: Positive anti-HPF4 was seen in 9% of aPL-positive SLE patients, 4% of aPL-negative SLE patients and 1% of controls (p = 0.026, aPL-positive SLE vs controls). Two of 12 subjects with positive anti-HPF4 had reactive SRAs. In SLE patients, anti-HPF4 significantly correlated with IgM APhL, IgM anti-beta2GP1, and inversely with complement C4. In immunoabsorption experiments, there was partial cross-reactivity of IgM anti-HPF4 with IgM APhL, but not with IgM anti-beta 2GP1. SLE patients with positive anti-HPF4 had increased odds of the antiphospholipid syndrome (APS; odds ratio (OR) 4.5, p = 0.019), and APS with arterial thrombosis (OR 6.1, p = 0.007). In multivariate linear regression analyses, APS and IgM APhL were independently associated with anti-HPF4. CONCLUSIONS: Anti-HPF4 is detectable in SLE patients with and without aPL in the absence of HIT, and is most prevalent in aPL-positive SLE patients. In this SLE cohort, anti-HPF4 correlates with IgM APhL, IgM anti-beta 2GP1 and inversely with C4, and is associated with manifestations of APS.

Inhibition of IkappaB kinase activity by sodium salicylate in vitro does not reflect its inhibitory mechanism in intact cells.

Sodium salicylate inhibits activation of the transcription factor NF-kappaB by blocking the phosphorylation and degradation of the NF-kappaB inhibitor IkappaBalpha. We previously demonstrated that salicylate inhibits IkappaBalpha degradation induced by tumor necrosis factor (TNF) but not by interleukin-1 (IL-1) and implicated p38 mitogen-activated protein kinase activation by salicylate in the inhibition of TNF-induced IkappaBalpha phosphorylation. Both TNF and IL-1 rapidly activate the IkappaB kinase (IKK) complex, containing the catalytic subunits IKKalpha and IKKbeta, which directly phosphorylates IkappaB proteins. Others have recently suggested that salicylate inhibits NF-kappaB activation by directly binding to IKKbeta. To clarify the mechanism whereby salicylate inhibits IKK activity, we examined its effects upon cytokine-induced IKK activity in intact cells and in vitro. Treatment of intact cells with salicylate inhibited TNF-induced but not IL-1-induced IKK activity, and this inhibition was prevented by the p38 inhibitor SB203580. In contrast, inhibition of IKK activity by salicylate in vitro was neither selective for TNF nor affected by SB203580. In vitro, salicylate treatment comparably inhibited the kinase activity of overexpressed IKKalpha and IKKbeta and also decreased p38 kinase activity. Therefore, direct inhibition of IKK activity in vitro does not reflect the inhibitory mechanism of salicylate in intact cells, which involves interference with TNF signaling.

Cell stress and MKK6b-mediated p38 MAP kinase activation inhibit tumor necrosis factor-induced IkappaB phosphorylation and NF-kappaB activation.

Tumor necrosis factor (TNF) exerts many actions through activation of the transcription factor NF-kappaB. NF-kappaB is sequestered in the cytosol by an inhibitory subunit IkappaB, which is inducibly phosphorylated by an IkappaB kinase complex and subsequently degraded. Sodium salicylate (NaSal) can block NF-kappaB activation by inhibiting IkappaBalpha phosphorylation. Recently, we used the specific p38 mitogen-activated protein (MAP) kinase inhibitor SB203580 to demonstrate that inhibition of TNF-induced IkappaBalpha phosphorylation requires NaSal-induced p38 activation. We demonstrate that NaSal similarly inhibits TNF-induced IkappaBbeta degradation in a p38-dependent manner. To further examine the role of p38, we determined whether other agents that activate p38 can block TNF-induced IkappaB phosphorylation and degradation. Sorbitol, H(2)O(2), and arsenite each blocked IkappaBalpha phosphorylation induced by TNF, and SB203580 reversed the inhibitory effects of sorbitol and H(2)O(2), but not arsenite. In addition, sorbitol and H(2)O(2) blocked TNF-induced but not interleukin-1-induced IkappaBalpha phosphorylation, whereas arsenite inhibited IkappaBalpha phosphorylation induced by TNF and interleukin-1. Transient expression of MAP kinase kinase (MKK) 6b(E), a constitutive activator of p38, reduced both TNF-induced phosphorylation of IkappaBalpha and NF-kappaB-dependent reporter activity. However, MKK7(D), a constitutive activator of c-Jun N-terminal kinases, failed to inhibit these TNF actions. Thus, sustained p38 activation by various stimuli inhibits TNF-induced IkappaB phosphorylation and NF-kappaB activation.

Cell-type-specific activation of c-Jun N-terminal kinase by salicylates.

Salicylates inhibit signaling by tumor necrosis factor (TNF), including TNF-induced activation of mitogen-activated protein kinases (MAPKs). On the other hand, we recently showed that in normal human diploid fibroblasts sodium salicylate (NaSal) elicits activation of p38 MAPK but not activation of c-Jun N-terminal kinase (JNK). Here we show that NaSal treatment of COS-1 or HT-29 cells produced a sustained c-Jun N-terminal kinase (JNK) activation. Activation of JNK or p38 MAPK by NaSal (or aspirin) was not due to a nonspecific hyperosmotic effect because much higher molar concentrations of sorbitol or NaCl were required to produce a similar activation. Three structurally unrelated nonsteroidal antiinflammatory drugs (ibuprofen, acetaminophen, and indomethacin) failed to induce significant activation of JNK or p38 MAPK, suggesting that cyclooxygenase inhibition is not the underlying mechanism whereby salicylates induce p38 MAPK and JNK activation. Activation of JNK and p38 MAPKs may be relevant for some antiinflammatory actions of salicylates.

Activation of p38 mitogen-activated protein kinase by sodium salicylate leads to inhibition of tumor necrosis factor-induced IkappaB alpha phosphorylation and degradation.

Many actions of the proinflammatory cytokines tumor necrosis factor (TNF) and interleukin-1 (IL-1) on gene expression are mediated by the transcription factor NF-kappaB. Activation of NF-kappaB by TNF and IL-1 is initiated by the phosphorylation of the inhibitory subunit, IkappaB, which targets IkappaB for degradation and leads to the release of active NF-kappaB. The nonsteroidal anti-inflammatory drug sodium salicylate (NaSal) interferes with TNF-induced NF-kappaB activation by inhibiting phosphorylation and subsequent degradation of the IkappaB alpha protein. Recent evidence indicated that NaSal activates the p38 mitogen-activated protein kinase (MAPK), raising the possibility that inhibition of NF-kappaB activation by NaSal is mediated by p38 MAPK. We now show that inhibition of TNF-induced IkappaB alpha phosphorylation and degradation by NaSal is prevented by treatment of cells with SB203580, a highly specific p38 MAPK inhibitor. Both p38 activation and inhibition of TNF-induced IkappaB alpha degradation were seen after only 30 s to 1 min of NaSal treatment. Induction of p38 MAPK activation and inhibition of TNF-induced IkappaB alpha degradation were demonstrated with pharmacologically achievable doses of NaSal. These findings provide evidence for a role of NaSal-induced p38 MAPK activation in the inhibition of TNF signaling and suggest a possible role for the p38 MAPK in the anti-inflammatory actions of salicylates. In addition, these results implicate the p38 MAPK as a possible negative regulator of TNF signaling that leads to NF-kappaB activation.

Coronary collateral recruitment: functional significance and relation to rate of vessel closure.

Studies in animals and humans have demonstrated the anatomic presence and functional significance of coronary collaterals. The extent of collateralization varies among species and among individuals. Collateral vessels are usually adequate for preserving resting regional and global ventricular function in the face of coronary obstruction. During stress, however, collateral supply may be inadequate. Collateral development is a time-dependent process during both the initial occlusion and following transient reflow and reclosure. Therefore when a previously collateralized coronary occlusion is recanalized and then recloses, the extent of the resulting collateral recruitment will depend, at least in part, upon the period of reflow between the two occlusions. The longer the reflow period, the less enhanced will be the collateralization. This is illustrated in the cases presented and has also been demonstrated in animal studies. The exact mechanisms for this recurrent collateral recruitment need further study.

Comparative dosing and efficacy of continuous-release nifedipine versus standard nifedipine for angina pectoris: clinical response, exercise performance, and plasma nifedipine levels.

To assess the dosing equivalency and the early and late antianginal efficacy of a gastrointestinal therapeutic system for once-daily, continuous-release nifedipine (N-GITS), 10 patients with stable angina pectoris, who were previously receiving chronic treatment with nifedipine, completed a 12-week trial comparing N-GITS with standard nifedipine. All patients (nine men and one woman; mean age 54 +/- 2 [SEM] years) who were receiving standard nifedipine (mean dose 40 +/- 5 mg/24 hr) for more than 2 weeks (mean 8 +/- 2 months, range 2 to 36 months) were switched to an equivalent once-daily dose (39 +/- 5 mg/24 hr) of N-GITS. Standard nifedipine and N-GITS were compared by symptom-limited exercise treadmill tests with a baseline test (A) performed 3 hours after a standard dose of nifedipine. Exercise tests were also performed after 2 weeks of treatment with N-GITS 3 hours (B) and 24 hours (C) after the drug was given, and after 12 weeks of treatment with N-GITS, 24 hours after dosing (D). Results of exercise tests showed no significant difference in mean exercise time--(A) 422 +/- 25 vs (B) 426 +/- 36 vs (C) 438 +/- 35 vs (D) 487 +/- 37 seconds. Likewise, there was no significant mean difference in peak double product, resting heart rate, peak exercise heart rate, or resting or maximal systolic blood pressure for any of the exercise test points. Furthermore, five patients (50%) reported side effects with standard nifedipine (all vasodilator-flushing, dizziness, or both), which resolved after treatment with N-GITS (p +/- 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of angioplasty guiding catheters for improved coronary artery opacification.

The following report describes the use of the high flow injection characteristics of a coronary angioplasty guiding catheter to improve coronary opacification in a patient with exceedingly high coronary runoff. This technique offers improved coronary visualization in special cases.