Glycine antagonist in neuroprotection for patients with acute stroke: GAIN Americas: a randomized controlled trial.

CONTEXT: Elucidation of the ischemic cascade has helped stimulate development of neuroprotective drugs aimed at limiting brain injury in the hours following an ischemic stroke. To date, none of these drugs has shown clinical efficacy. OBJECTIVE: To examine the efficacy of gavestinel (GV150526), an antagonist of the glycine site of the N-methyl-D-aspartate receptor, as a neuroprotective therapy for acute ischemic stroke when administered within 6 hours of symptom onset. DESIGN: The Glycine Antagonist in Neuroprotection (GAIN) Americas trial, a randomized, double-blind placebo-controlled trial with enrollment from April 1998 to October 1999. SETTING: One hundred thirty-two hospital centers across the United States and Canada. PATIENTS: The primary efficacy population consisted of 1367 ischemic stroke patients with a predefined level of limb weakness and functional independence prior to stroke, stratified at randomization by age (75 years) and initial stroke severity (National Institutes of Health [NIH] Stroke Scale scores of 2-5, 6-13, or >/=14). INTERVENTION: Patients were randomly assigned to receive an intravenous loading dose (800 mg) plus 5 maintenance doses (200 mg every 12 hours) of gavestinel (n = 701) or placebo (n = 666) for 3 days. MAIN OUTCOME MEASURE: Functional capability at 3 months, measured by the Barthel Index (BI), with scores trichotomized as dead/0-55, 60-90, and 95-100, compared between the gavestinel and placebo groups. RESULTS: Treatment groups were well matched for baseline characteristics. For each group, median NIH Stroke Scale was 12, median age was 72 years, and median time to treatment was 5.2 hours. No statistically significant improvement on the 3-month BI trichotomy was demonstrated for gavestinel (P =.79). The proportion who were functionally independent (BI score = 95-100) was 39% in the gavestinel group and 37% in the placebo group. No statistically significant difference in 3-month survival was observed using Kaplan-Meier curves (P =.11). No other secondary end point suggested an advantage for gavestinel. Among the 333 patients (24%) who received recombinant tissue-type plasminogen activator, there was also no benefit for gavestinel (P =.53). There were no serious safety issues. CONCLUSION: In this study, gavestinel administered up to 6 hours after an acute ischemic stroke did not improve functional outcome at 3 months.

Intracranial hemorrhage after coronary thrombolysis with tissue plasminogen activator.

PURPOSE AND METHODS: We analyzed the clinical, laboratory, and radiologic data in nine patients who sustained an intracranial hemorrhage (ICH) after receiving intravenous recombinant tissue plasminogen activator (rt-PA) and heparin for treatment of acute myocardial infarction (MI). Our purpose was to delineate the clinical and radiologic features of the ICHs, as well as to determine their potential risk factors and mechanisms. RESULTS: Among 1,700 patients with an acute MI treated with an investigational two-chain rt-PA, duteplase (Burroughs Wellcome Co., Research Triangle Park, NC), nine (0.53%) developed symptomatic ICH. Neurologic symptoms occurred between 7 and 96 hours after onset of rt-PA therapy. All patients received heparin concomitantly for prevention of coronary reocclusion. The activated partial thromboplastin times (aPTTs) in five of eight (63%) patients at onset of ICH were excessively prolonged (greater than two times control); hypofibrinogenemia occurred in only one of five (20%) patients tested; and thrombocytopenia was present in only one of the nine (11%) patients. Fibrin degradation products (FDPs) were elevated in all five patients tested. Minor hemorrhage (not requiring transfusion) outside the central nervous system occurred in five of the nine patients with ICH. The ICHs were often of lobar location and of moderate to large size. They occurred at multiple sites in three patients, and were fatal in four instances (44%). CONCLUSIONS: The incidence of ICH in this series was low, and consistent with figures reported from studies with alteplase in patients with acute MI. The mechanisms of these hemorrhages remain unclear; while hypofibrinogenemia was not a uniform finding, excessive prolongation of the aPTT and elevated FDPs may have contributed to the occurrence of ICH in some patients. Still unidentified local cerebrovascular factors may play an additional role in causing ICH. In order to further clarify the mechanisms of ICH in the setting of thrombolytic therapy, prospective data collection on probable risk factors for ICH in patients with acute MI treated with rt-PA will be required.

Primary renovascular effects of erythromycin in the rat: relationship to cyclosporine nephrotoxicity.

Erythromycin is known to exacerbate cyclosporine nephrotoxicity. This has been attributed to the potential of erythromycin to reduce the hepatic microsomal metabolism and clearance of cyclosporine. Erythromycin may also be nephrotoxic. We tested the hypothesis that erythromycin may have direct effects on the renal vasculature which are additive or synergistic with the effects of cyclosporine. Sprague-Dawley rats were administered graded doses of either erythromycin, 2.5, 5, 7.5, and 10 mg/kg BW/min i.v. over consecutive 10-min intervals; cyclosporine, 1, 2, 3, and 4 mg/kg BW/min i.v. over consecutive 10-min intervals; or both drugs simultaneously. In separate experiments, identical doses of erythromycin or cyclosporine were infused intravenously following acute unilateral renal denervation. Infusion of erythromycin led to an initial decline in arterial blood pressure whereas infusion of cyclosporine resulted in a dose-related increase in arterial blood pressure. Despite these different systemic effects, each drug alone produced a striking decrease in renal blood flow. This effect was more pronounced when the drugs were infused concomitantly. The reduction in renal blood flow occurred in an additive manner as a direct consequence of increased renal vascular resistance. Prior renal denervation did not modify the response to either erythromycin or cyclosporine. These results demonstrate that cyclosporine-induced vasoconstriction is exacerbated by erythromycin and suggest that the decline in renal function observed in patients coadministered these drugs may be due in part to additive renovascular toxicity.

The metabolite 1 alpha,25-dihydroxyvitamin D3 enhances lymphokine-mediated activation of the oxidative metabolism of the U937 cell line and phosphorylation of a 48-kD respiratory burst-associated protein.

U937 cells respond to a variety of stimuli with increased differentiation as manifested by reduced growth, increased adherence, increased expression of several surface receptors, and increased capacity for phagocytosis and formation of reactive oxygen intermediates. In the present study the effects of lymphocyte conditioned media, recombinant interferon-gamma (IFN-gamma), and 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the ability to form reactive oxygen intermediates by U937 cells were measured by using the luminol-dependent luminescence (LDL) assay. Neither 1,25(OH)2D3 alone nor IFN-gamma alone enhanced competence for phorbol myristate acetate-stimulated LDL. Cells were capable of moderate LDL after exposure to lymphocyte conditioned media, and this was enhanced by 1,25(OH)2D3 (10(-8) mol/L) and other vitamin D metabolites at higher concentrations. This effect was not secondary to accelerated production of myeloperoxidase, which is important in the LDL assay. Enhanced phorbol myristate acetate-stimulated phosphorylation of a 48-kd substrate was observed in 32P-labeled intact cells treated with 1,25(OH)2D3 alone or in combination with IFN-gamma. Treatment of cells with IFN-gamma or lymphocyte conditioned media did not alter phosphorylation. These results support the concept that 1,25(OH)2D3 plays a role in phagocyte differentiation and activation beyond the effects of lymphokines. Protein kinase C-mediated phosphorylation reactions may be necessary for the ability of U937 cells to reduce O2 and required for maximal activity under some conditions of incubation.

Acid phosphatase activity in mononuclear phagocytes and the U937 cell line: monocyte-derived macrophages express tartrate-resistant acid phosphatase.

Tartrate-resistant acid phosphatase (TRAcP) is used as a marker for osteoclasts, which are believed to be derived from phagocytic cells or phagocyte stem cell precursors. To further investigate the relationship between monocytic phagocytes and osteoclasts, acid phosphatase (AcP) activity was measured by three different techniques in human peripheral blood monocytes, monocyte-derived macrophages, and the U937 cell line. We found that cytochemistry and gel electrophoresis led to similar results, but that the colorimetric assay was inconsistent. Normal human peripheral monocytes expressed both tartrate-sensitive and -resistant AcP. In culture these cells formed polykaryons and expressed TRAcP activity that was further identified as an isoenzyme associated with bone tissue. In contrast, the U937 cells did not express TRAcP activity as measured by gel electrophoresis. Both U937 cells and monocytes possess material that interferes with interpretation of the colorimetric assay of AcP. The presence of TRAcP in monocyte-derived macrophages further supports the relationship between phagocytic cells and bone osteoclasts.

1,25-Dihydroxyvitamin D3 activates secretion of hydrogen peroxide by human monocytes.

Human blood monocytes cultured in the presence of 1,25(OH)2D3 developed enhanced competence for secretion of H2O2 relative to cells suspended in media. This effect was maximal at a concentration of 10(-8) M 1,25(OH)2D3. After 3 days of incubation, monocyte-derived macrophages (MDM) exposed to 1,25(OH)2D3 demonstrated competence for secretion of H2O2 equivalent to cells exposed to recombinant IFN-gamma. Both IFN-gamma and 1,25(OH)2D3 offset decay of this function among cells in culture after 7 days. Simultaneous exposure of cells to 1,25(OH)2D3 and IFN-gamma did not activate competence for H2O2 secretion more than either agent alone. 24,25(OH)2D3 and 25(OH)2D3 activated MDM but at higher concentration than required for 1,25(OH)2D3. Progesterone did not affect H2O2 production. Incubation of MDM with a monoclonal antibody directed against IFN-gamma inhibited activation induced by lymphokine, and to a lesser extent by cells activated with IFN-gamma; this antibody had an insignificant effect on cells treated with 1,25(OH)2D3. These results suggest that 1,25(OH)2D3 exerts a receptor-mediated effect on monocyte function that results in cellular activation as manifested by enhanced competence for secretion of H2O2. It is possible that smaller concentrations of 1,25(OH)2D3 present in serum are permissive for macrophage activation, or that monocytic phagocytes are exposed to high concentrations of vitamin D metabolites under some clinical circumstances.