Diverging associations of an intended early invasive strategy compared with actual revascularization, and outcome in patients with non-ST-segment elevation acute coronary syndrome: the problem of treatment selection bias

AIMS: In several observational studies, revascularization is associated with substantial reduction in mortality in patients with non-ST-segment elevation acute coronary syndrome (nSTE-ACS). This has strengthened the belief that routine early angiography would lead to a reduction in mortality. We investigated the association between actual in-hospital revascularization and long-term outcome in patients with nSTE-ACS included in the ICTUS trial. METHODS AND RESULTS: The study population of the present analysis consists of ICTUS participants who were discharged alive after initial hospitalization. The ICTUS trial was a randomized, controlled trial in which 1200 patients were randomized to an early invasive or selective invasive strategy. The endpoints were death from hospital discharge until 4 year follow-up and death or spontaneous myocardial infarction (MI) until 3 years. Among 1189 patients discharged alive, 691 (58%) underwent revascularization during initial hospitalization. In multivariable Cox regression analyses, in-hospital revascularization was independently associated with a reduction in 4 year mortality and 3 year event rate of death or spontaneous MI: hazard ratio (HR) 0.59 [95% confidence interval (CI) 0.37-0.96] and 0.46 (95% CI 0.31-0.68). However, when intention-to-treat analysis was performed, no differences in cumulative event rates were observed between the early invasive and selective invasive strategies: HR 1.10 (95% CI 0.70-1.74) for death and 1.27 (95% CI 0.88-1.85) for death or spontaneous MI. CONCLUSION: The ICTUS trial did not show that an early invasive strategy resulted in a better outcome than a selective invasive strategy in patients with nSTE-ACS. However, similar to retrospective analyses from observational studies, actual revascularization was associated with lower mortality and fewer MI. Whether an early invasive strategy leads to a better outcome than a selective invasive strategy cannot be inferred from the observation that revascularized patients have a better prognosis in non-randomized studies.     

Antisickling effects of 2,3-diphosphoglycerate depletion

Elevation of 2,3-bisphosphoglycerate (2,3-DPG) in sickle erthrocytes (SS RBCs) and concomitant acidification of the cell interior promote polymerization by decreasing the solubility (csat) of deoxyhemoglobin S. The antisickling effect of 2,3-DPG depletion was evaluated after activation of the 2,3-DPG phosphatase activity of bisphosphoglycerate mutase by glycolate-2-phosphate, leading to rapid loss of intracellular 2,3-DPG. To ensure its maximal reduction in a physiologic medium, isosmotic CO2/bicarbonate-buffered saline, pH 7.0, was used. Substitution of K+ for Na+ as the major extracellular cation suppressed K:Cl cotransport, prevented cell shrinkage, and allowed demonstration of the full antisickling effect of 2,3-DPG depletion. The modest effect on solubility per se of removing intraerythrocytic 2,3-DPG (delta Csat = 1.6 g/dL) was amplified into a much larger antisickling effect by interaction with three other cellular variables affecting solubility and polymer content (intracellular pH, O2 saturation, and mean cell hemoglobin concentration). Acting in concert, these four antisickling effects (three solubilizing, one osmotic) reduced polymer fraction of glycolate-treated SS RBCs by 32% to 63%, with a concomitant decrease in sickling of 46% to 95% at the nominal pO2 of the microcirculation (20 mm Hg). A decrement in sickling of this magnitude should significantly ameliorate the vasoocclusive severity of sickle cell disease.     

A selective cyclooxygenase 2 inhibitor suppresses the growth of H-ras-transformed rat intestinal epithelial cells

BACKGROUND & AIMS: Constitutive expression of cyclooxygenase 2 (COX-2) has been found in 85% of colorectal cancers. Ras mutations are found in 50% of colorectal adenocarcinomas. The aim of this study was to determine the role of COX-2 in ras-induced transformation in rat intestinal epithelial (RIE) cells. METHODS: Cell growth was determined by cell counts. The expression of COX-2 was examined by Northern and Western analyses. For tumorigenicity assays, cells were inoculated into dorsal subcutaneous tissue of athymic nude mice. DNA-fragmentation assays were performed to detect apoptosis. RESULTS: The expression of COX-2 was increased in RIE-Ras cells at both messenger RNA (9-fold) and protein (12-fold) levels. Prostaglandin I2 levels were elevated 2.15-fold in RIE-Ras cells. Serum deprivation further increased COX-2 expression 3.8-fold in RIE-Ras cells. Treatment with a selective COX-2 antagonist (SC58125) inhibited the growth of RIE-Ras cells through inhibition of cell proliferation and by induction of apoptosis. SC-58125 treatment reduced the colony formation in Matrigel by 83.0%. Intraperitoneal administration of SC-58125 suppressed RIE-Ras tumor growth in nude mice by 60.3% in 4 weeks. SC-58125 treatment also induced apoptosis in RIE-Ras cells as indicated by increased DNA fragmentation. CONCLUSIONS: Overexpression of COX-2 may contribute to tumorigenicity of ras-transformed intestinal epithelial cells. Selective inhibition of COX-2 activity inhibits growth of ras-transformed intestinal epithelial cells and induces apoptosis. (Gastroenterology 1997 Dec;113(6):1883-91)     

Heparin oligosaccharides bind L- and P-selectin and inhibit acute inflammation

Initial attachment of leukocytes to the vessel wall at sites of inflammation is supported by a family of carbohydrate-binding adhesion molecules called the selectins. Selectin ligands include sialyl-Lewis x (sLex, Neu5Ac alpha 2-3Gal beta 1-4[Fuc alpha 1-3]GlcNAc--) and related structures. We report here that defined heparin oligosaccharides interact with the selectins. Heparin chains containing four or more monosaccharide residues inhibited the function of L- and P-selectin, but not E-selectin, in vitro. In a competition enzyme-linked immunosorbent assay measuring inhibition of solution-phase selectin-Ig fusion proteins (selectin-Ig) binding to immobilized bovine serum albumin-sLex neoglycoprotein, a heparin-derived tetrasaccharide mixture inhibited 50% of L- and P-selectin-Ig binding (IC50) at 200 +/- 40 mumol/L and 850 +/- 110 mumol/L, respectively. A single hexasulfated tetrasaccharide (delta UA2S alpha 1-4GlcNS6S alpha 1-4IdoA2S alpha 1- 4GlcNS6S) was particularly active against L- and P-selectin-Ig (IC50 = 46 +/- 5 mumol/L and 341 +/- 24 mumol/L). By comparison, the tetrasaccharide sLex was not inhibitory at concentrations up to 1 mmol/L. In cell adhesion assays, heparin tetrasaccharides reduced binding of neutrophils to COS cells expressing P-selectin but not to COS cells expressing E-selectin. They also blocked colon cancer cell adhesion to L- and P-selectin but not E-selectin. In a model of acute inflammation, intravenously administered heparin tetrasaccharides diminished influx of neutrophils into the peritoneal cavities of thioglycollate-treated mice. We conclude that heparin oligosaccharides, including non-anticoagulant tetrasaccharides, are effective L- and P- selectin inhibitors in vitro and have anti-inflammatory activity in vivo.     

Role of upstream DNase I hypersensitive sites in the regulation of human alpha globin gene expression

Erythroid-specific DNase 1 hypersensitive sites have been identified at the promoters of the human alpha-like genes and within the region from 4 to 40 kb upstream of the gene cluster. One of these sites, HS-40, has been shown previously to be the major regulator of tissue-specific alpha-globin gene expression. We have now examined the function of other hypersensitive sites by studying the expression in mouse erythroleukemia (MEL) cells of various fragments containing these sites attached to HS-40 and an alpha-globin gene. High level expression of the alpha gene was observed in all cases. When clones of MEL cells bearing a single copy of the alpha-globin gene fragments were examined, expression levels were similar to those of the endogenous mouse alpha genes and similar to MEL cells bearing beta gene constructs under the control of the beta-globin locus control region. However, there was no evidence that the additional hypersensitive sites increased the level of expression or conferred copy number dependence on the expression of a linked alpha gene in MEL cells.     

Phosphorylation of factor Va and factor VIIIa by activated platelets

Platelet activation leads to the incorporation of 32[PO4(2-)] into bovine coagulation factor Va and recombinant human factor VIII. In the presence of the soluble fraction from thrombin-activated platelets and (gamma-32P) adenosine triphosphate, radioactivity is incorporated exclusively into the M(r) = 94,000 heavy chain (H94) of factor Va and into the M(r) = 210,000 to 90,000 heavy chains as well into the M(r) = 80,000 light chain of factor VIII. Proteolysis of the purified phosphorylated M(r) = 94,000 factor Va heavy chain by activated protein C (APC) gave products of M(r) = 70,000, 24,000, and 20,000. Only the intermediate M(r) = 24,000 fragment contained radioactivity. Because the difference between the M(r) = 24,000 and M(r) = 20,000 fragments is located on the COOH-terminal end of the bovine heavy chain, phosphorylation of H94 must occur within the M(r) = 4,000 peptide derived from the carboxyl-terminal end of H94 (residues 663 through 713). Exposure of the radioactive factor VIII molecule to thrombin ultimately resulted in a nonradioactive light chain and an M(r) = 24,000 radioactive fragment that corresponds to the carboxyl-terminal segment of the A1 domain of factor VIII. Based on the known sequence of human factor VIII, phosphorylation of factor VIII by the platelet kinase probably occurs within the acidic regions 337 through 372 and 1649 through 1689 of the procofactor. These acidic regions are highly homologous to sequences known to be phosphorylated by casein kinase II. Results obtained using purified casein kinase II gave a maximum observed stoichiometry of 0.6 mol of 32[PO4(2-)]/mol of factor Va heavy chain and 0.35 mol of 32[PO4(2-)]/mol of factor VIII. Phosphoamino acid analysis of phosphorylated factor Va by casein kinase II or by the platelet kinase showed only the presence of phosphoserine while phosphoamino acid analysis of phosphorylated factor VIII by casein kinase II showed the presence of phosphothreonine as well as small amounts of phosphoserine. The platelet kinase responsible for the phosphorylation of the two cofactors was found to be inhibited by several synthetic protein kinase inhibitors. Finally, partially phosphorylated factor Va was found to be more sensitive to APC inactivation than its native counterpart. Our findings suggest that phosphorylation of factors Va and VIIIa by a platelet casein kinase II- like kinase may downregulate the activity of the two cofactors.     

Oral sumatriptan in the acute treatment of migraine and migraine recurrence in general practice

We investigated the efficacy, safety and tolerability compared with placebo of a second dose of oral sumatriptan 100 mg in 1349 general practice patients who had already treated a moderate or severe migraine headache with 100 mg sumatriptan 4 h earlier. Headache was relieved by the first sumatriptan dose in about 70% of patients, but the second dose did not produce significantly more relief than placebo, either in nonresponders or in the group as a whole, nor did it reduce other symptoms (photophobia, nausea, vomiting, etc,) at 8 h, or influence the incidence of headache recurrence. The drug was well-tolerated, and a further single dose was effective in treating recurrence after initial relief. A single 100 mg dose of sumatriptan is an effective acute treatment for migraine. A second dose should be reserved for treating headache recurrence.      

Arsenic intoxication as a cause of megaloblastic anemia

We have described a case of chronic arsenic intoxication associated with pancytopenia and megaloblastic erythropoiesis. The patient had the typical laboratory manifestations of effective erythorpoiesis due to a megaloblastic process, including macroovalocytes, mild pancytopenia, low reticulocyte index, increased marrow cellularity with erythroid hyperplasia, and morphologic evidence of megaloblastic maturation in the marrow. The patient's serum folate and vitamin B12 were normal, and the anemia regressed without therapy. Our case suggests that the combination of megaloblastosis with normoblastic or megaloblastic karyorrhexis,should raise the suspicion of arsenic intoxication in the mind of the observer. In addition, arsenic should be added to the list of agents causing a reversible megaloblastic anemia.