ALBERT

Beschreibung: The Southeastern Cancer Study Group conducted a post-remission induction randomized trial in adult acute myelogenous leukemia to assess the efficacy of alternate drug therapy during consolidation and of immunotherapy during maintenance. Of 508 evaluable patients entered into the study, 335 (66%) achieved a complete remission treated with a 7-day infusion of cytosine arabinoside at a dose of 100 mg/sq m/day and 3 days of daunorubicin at a dose of 45 mg/sq m/day. Those in remission were randomized to receive 3 courses of 1 of 3 consolidation regimens: (A) a continuous infusion of 5-azacytidine, 150 mg/sq m/day for 5 days; (B) 5-azacytidine plus beta-deoxythioguanosine, 300 mg/sq m/day for 5 days; or (C) cytosine arabinoside, 100 mg/sq m/day intravenously, and thioguanine, 100 mg/sq m orally every 12 hr, plus daunorubicin, 10 mg/sq m every 24 hr daily for 5 days. There was no difference in relapse rate among the 3 arms. Those completing consolidation and remaining in remission were randomized to 1 of 3 maintenance regimens: (D) chemotherapy, 5-day infusion of cytosine arabinoside and 2 days of daunorubicin (same doses as induction) given every 13 wk for 1 yr; (E) BCG given twice weekly for 1 mo and then monthly for 1 yr; or (F) the combination of regimens D and E. The median duration of remission was significantly better on regimen D (17.4 versus 9.4 and 9.5 mo), and median survival was 29 mo compared to 21 mo for the other regimens. Those given different drugs during consolidation than used for induction (regimens A and B) and subsequent chemotherapy for maintenance (regimen D) had the longest remission durations and survival. Immunotherapy was not as good as intensive chemotherapy for maintenance.

Beschreibung: An activated prothrombin complex concentrate (Autoplex) was infused for the treatment of 102 bleeding episodes in 18 hemophilia A patients with antibody to factor VIII who were previously known as high responders. Among 95 bleeding episodes treated with a single infusion of the concentrate [43–107 factor VIII correcting units (FECU)/kg], only 1 anamnestic response was observed. On the contrary, a significant rise in antibody titer occurred following 2 of 4 double (at 8–12 hr interval) and all 3 multiple (over3 –10 days) infusions of Autoplex. The occurrence of immune responses may be explained by the presence of factor VIII coagulant antigen (VIII:CAg) in the 26 batches of Autoplex tested by two-site immunoradiometric assay (10-–36 U/vial). The anamnestic response was not correlated to the batch used nor to the amount (0.6–7.8 U/kg/day) of VIII:CAg infused per day. However, exposure to the concentrate over several days appeared to be the major predisposing factor for an immune response.

Beschreibung: The Southeastern Cancer Study Group conducted a post-remission induction randomized trial in adult acute myelogenous leukemia to assess the efficacy of alternate drug therapy during consolidation and of immunotherapy during maintenance. Of 508 evaluable patients entered into the study, 335 (66%) achieved a complete remission treated with a 7-day infusion of cytosine arabinoside at a dose of 100 mg/sq m/day and 3 days of daunorubicin at a dose of 45 mg/sq m/day. Those in remission were randomized to receive 3 courses of 1 of 3 consolidation regimens: (A) a continuous infusion of 5-azacytidine, 150 mg/sq m/day for 5 days; (B) 5-azacytidine plus beta-deoxythioguanosine, 300 mg/sq m/day for 5 days; or (C) cytosine arabinoside, 100 mg/sq m/day intravenously, and thioguanine, 100 mg/sq m orally every 12 hr, plus daunorubicin, 10 mg/sq m every 24 hr daily for 5 days. There was no difference in relapse rate among the 3 arms. Those completing consolidation and remaining in remission were randomized to 1 of 3 maintenance regimens: (D) chemotherapy, 5-day infusion of cytosine arabinoside and 2 days of daunorubicin (same doses as induction) given every 13 wk for 1 yr; (E) BCG given twice weekly for 1 mo and then monthly for 1 yr; or (F) the combination of regimens D and E. The median duration of remission was significantly better on regimen D (17.4 versus 9.4 and 9.5 mo), and median survival was 29 mo compared to 21 mo for the other regimens. Those given different drugs during consolidation than used for induction (regimens A and B) and subsequent chemotherapy for maintenance (regimen D) had the longest remission durations and survival. Immunotherapy was not as good as intensive chemotherapy for maintenance.

Beschreibung: Previous studies have suggested a role for platelet CD40L in thrombosis and atherosclerosis. However, there are contradictory reports on the biologic activity of its soluble variant (sCD40L) and the involved receptor signaling pathways (CD40 vs αIIbβ3). Furthermore, CD40L mAb-associated thromboembolic complications in recent human and animal studies have raised additional questions about the pro-thrombotic properties of this molecule. This study was conducted to further investigate the function of the CD40/CD40L dyad in primary hemostasis and platelet function. CD40−/− and CD40L−/− mice and mice deficient for both genes (“double knock-out”) showed prolonged tail vein bleeding and platelet function analyzer (PFA-100) closure times as compared to their wild-type littermates, indicating an inherited defect in platelet function. Recombinant human sCD40L (rsCD40L), chemical cross-linking of which yielded a single reaction product compatible with a trimeric structure of the protein in solution, bound to CD40 on resting platelets and induced CD62P (P-selectin) expression in a concentration-dependent manner (0–5 μg/ml) from 1±1 to 23±5% positivity (means±SD, n=4–8; P

Beschreibung: Actin is an important cytoskeletal protein; new actin synthesis occurs during differentiation of many motile cells. To better understand the process of myeloid maturation, the change in actin content during induced maturation of HL-60 human promyelocytic leukemia cells was studied. HL-60 cells induced toward myeloid maturation by a 5-day exposure to dimethylformamide showed an 86% increase in a 43,000 mol wt protein comigrating with rabbit muscle actin on dodecyl sulfate polyacrylamide gels. To further demonstrate that this was an increase in actin content, the total actin content of lysed HL-60 cells was measured by the ability of actin to inhibit DNAase I. Using this assay, actin content of HL-60 cells increased 96% during induced differentiation. The amount of incorporation of 3H-leucine into actin doubled after a 5-day exposure to dimethylformamide, suggesting the increase in actin was due primarily to new synthesis. Total new protein synthesis increased 2–7-fold during differentiation. Additional analysis of polyacrylamide gels showed increased quantities and new synthesis of a high molecular weight protein comigrating with rabbit muscle myosin. This study shows that actin content increases during myeloid maturation. It also demonstrates that the HL-60 cell line is a useful model to study both functional and biochemical events during human myeloid differentiation.

Beschreibung: Successful immunologic control of HIV infection is achieved only in rare individuals. Dendritic cells (DCs) are required for specific antigen presentation to naive T lymphocytes and for antiviral, type I interferon secretion. Two major blood DC populations are found: CD11c+ (myeloid) DCs, which secrete IL-12, and CD123+ (IL-3–receptor+) DCs (lymphoid), which secrete type I interferons in response to viral stimuli. The authors have previously found a decreased proportion of blood CD11c+ DCs in chronic HIV+ patients. In this study, 26 to 57 days after infection and before treatment, CD123+ and CD11c+ DC numbers were dramatically reduced in 13 HIV+ patients compared with 13 controls (P = .0002 and P = .001, respectively). After 6 to 12 months of highly active antiretroviral therapy, DC subpopulation average numbers remained low, but CD123+ DC numbers increased again in 5 of 13 patients. A strong correlation was found between this increase and CD4 T-cell count increase (P = .0009) and plasma viral load decrease (P = .009). Reduced DC numbers may participate in the functional impairment of HIV-specific CD4+ T cells and be responsible for the low type I interferon responsiveness already known in HIV infection. The restoration of DC numbers may be predictive of immune restoration and may be a goal for immunotherapy to enhance viral control in a larger proportion of patients.

Beschreibung: The aim was to better understand the function of von Willebrand factor (vWF) A1 domain in shear-induced platelet aggregation (SIPA), at low (200) and high shear rate (4000 seconds-1) generated by a Couette viscometer. We report on 9 fully multimerized recombinant vWFs (rvWFs) expressing type 2M or type 2B von Willebrand disease (vWD) mutations, characterized respectively by a decreased or increased binding of vWF to GPIb in the presence of ristocetin. We expressed 4 type 2M (-G561A, -E596K, -R611H, and -I662F) and 5 type 2B (rvWF-M540MM, -V551F, -V553M, -R578Q, and -L697V). SIPA was strongly impaired in all type 2M rvWFs at 200 and 4000 seconds-1. Decreased aggregation was correlated with ristocetin binding to platelets. In contrast, a distinct effect of botrocetin was observed, since type 2M rvWFs (-G561A, -E596K, and -I662F) were able to bind to platelets to the same extent as wild type rvWF (rvWF-WT). Interestingly, SIPA at 200 and 4000 seconds-1 confirmed the gain-of-function phenotype of the 5 type 2B rvWFs. Our data indicated a consistent increase of SIPA at both low and high shear rates, reaching 95% of total platelets, whereas SIPA did not exceed 40% in the presence of rvWF-WT. Aggregation was completely inhibited by monoclonal antibody 6D1 directed to GPIb, underlining the importance of vWF-GPIb interaction in type 2B rvWF. Impaired SIPA of type 2M rvWF could account for the hemorrhagic syndrome observed in type 2M vWD. Increased SIPA of type 2B rvWF could be responsible for unstable aggregates and explain the fluctuant thrombocytopenia of type 2B vWD.

Beschreibung: The aim was to better understand the function of von Willebrand factor (vWF) A1 domain in shear-induced platelet aggregation (SIPA), at low (200) and high shear rate (4000 seconds-1) generated by a Couette viscometer. We report on 9 fully multimerized recombinant vWFs (rvWFs) expressing type 2M or type 2B von Willebrand disease (vWD) mutations, characterized respectively by a decreased or increased binding of vWF to GPIb in the presence of ristocetin. We expressed 4 type 2M (-G561A, -E596K, -R611H, and -I662F) and 5 type 2B (rvWF-M540MM, -V551F, -V553M, -R578Q, and -L697V). SIPA was strongly impaired in all type 2M rvWFs at 200 and 4000 seconds-1. Decreased aggregation was correlated with ristocetin binding to platelets. In contrast, a distinct effect of botrocetin was observed, since type 2M rvWFs (-G561A, -E596K, and -I662F) were able to bind to platelets to the same extent as wild type rvWF (rvWF-WT). Interestingly, SIPA at 200 and 4000 seconds-1 confirmed the gain-of-function phenotype of the 5 type 2B rvWFs. Our data indicated a consistent increase of SIPA at both low and high shear rates, reaching 95% of total platelets, whereas SIPA did not exceed 40% in the presence of rvWF-WT. Aggregation was completely inhibited by monoclonal antibody 6D1 directed to GPIb, underlining the importance of vWF-GPIb interaction in type 2B rvWF. Impaired SIPA of type 2M rvWF could account for the hemorrhagic syndrome observed in type 2M vWD. Increased SIPA of type 2B rvWF could be responsible for unstable aggregates and explain the fluctuant thrombocytopenia of type 2B vWD.

Beschreibung: Intracoronary transfer of autologous bone marrow cells (BMCs) has been shown to promote recovery of left ventricular (LV) systolic function in patients with acute myocardial infarction. (BOOST Trial; Wollert et al. Lancet, 2004, 364 141-8). Although the mechanisms of this effect remain to be established, homing of BMCs to the infarcted LV is probably a crucial early event. We determined BMC tissue distribution after therapeutic application in nine patients with a first ST-elevation myocardial infarction, who had undergone stenting of the infarct-related artery (all male; median age 43 ys; range 36 – 66). The study was approved by the local ethics committee and all patients provided written informed consent. Time from symptom onset to percutaneous coronary intervention (PCI) was 8 h (3–27) and median maximum CK level was 1767 U/l. Cells were harvested from the posterior iliac crest during short anesthesia with etomidate and midazolam and subjected to 4% gelatine polysuccinate sedimentation to obtain a preparation of unfractionated BMCs. 2.5 ± 0,7 x 108 unfractionated BMCs (10% of the harvested cell number) were radiolabeled with 100 MBq 2′-[18F]-fluoro-deoxyglucose (FDG) and infused into the infarct-related coronary artery (i.c., n=3 patients) or injected via an antecubital vein (i.v., n=3 patients). In 3 additional patients, CD34pos cells were immunomagnetically enriched from unfractionated BMCs (Clinimacs, Miltenyi, Germany), labeled with FDG, and infused i.c. Cell transfer was performed 8±2 days after stenting. Following application of FDG labelled cells all patients received 20 ± 6 x 108 non-labeled BMCs i.c. (i.e. the cell dosage that improved cell function in the BOOST trial). More than 98% of the total radioactivity infused was cell-bound. Cell viability after FDG-labeling was 95±2%. Sixty minutes after cell transfer, all patients underwent 3D-positron emission tomography imaging. After i.c. transfer, 3.4±1.4% of FDG-labeled unfractionated BMCs were detected in the infarcted LV; the remaining activity was found primarily in the liver and spleen. After i.v. transfer, only background activity was detectable in the infarcted LV. After i.c. transfer of FDG-labeled CD34-enriched cells, 25±13% of the total activity was detectable in the infarcted LV. Unfractionated BMCs engrafted in the infarct center and border zone, CD34pos cell homing was more pronounced in the border zone. FDG-labeling can be used to monitor myocardial homing and tissue distribution of BMCs after therapeutic application. I.c. transfer is superior to i.v. application in terms of BMC homing in the the infarcted LV. CD34-enriched cells display a 7-fold higher retention in the infarcted LV as compared to unfractionated BMCs.

Beschreibung: Platelet-derived CD154 has been shown to play an important role in platelet function and arterial thrombus formation in vivo. These properties of CD154 may be mediated by signaling via the CD40 receptor and/or the α IIβ 3 integrin on the platelet surface. CD154 expressed on activated platelets can also induce an inflammatory response, including the production of tissue factor (TF) in endothelial cells and monocytes, in a CD40-dependent manner. TF-driven disseminated intravascular coagulation (DIC) with activation and subsequent sequestration of platelets are common features in murine models of hematogenous metastasis and endotoxemia. In both models, platelet- and fibrin-rich thrombi are formed in the microvasculature, and in the model of metastasis, these microthrombi are believed to enhance tumor cell lodgement, extravasation and colony formation. It is therefore reasonable to hypothesize that the CD154 pathway also plays a critical role in the processes of hematogenous tumor cell dissemination and LPS-induced consumptive coagulopathy. We have used a gene knockout model to test these hypotheses. To assess tumor cell-induced coagulopathy, wild-type (WT) mice and mice deficient for CD154 (Cd154−/−), CD40 (Cd40−/−) or both (Dbl−/−), (n=5–12 per group) were injected intravenously with B16 melanoma cells (1X106). Fifteen minutes later, blood was collected by cardiac puncture to measure platelet counts, factor X (FX) activity and plasma hemoglobin (pHb), a sensitive marker of microangiopathic hemolytic anemia following microvascular thrombosis. To assess metastasis, mice (n=10–20 per group) were injected via the tail vein with B16 tumor cells (2x105) and surface tumor nodules were counted macroscopically 18 days later. To assess endotoxin-induced coagulopathy, mice (n=10 per group) were injected intraperitoneally with LPS (50 mg/kg) and platelet count, FX and fibrinogen levels were measured after 8 hours. All groups of animals had similar baseline parameters. However, following tumor cell injection, platelet counts were reduced by 73% and 72%, in WT and Cd40−/− mice respectively, compared to 50% in Cd154−/− and 54% in Dbl−/− mice (P