Deregulation of kinase signaling and lymphoid development in EBF1-PDGFRB ALL leukemogenesis.

The chimeric fusion oncogene early B-cell factor 1-platelet-derived growth factor receptor-ß (EBF1-PDGFRB) is a recurrent lesion observed in Philadelphia-like B-acute lymphoblastic leukemia (B-ALL) and is associated with particularly poor prognosis. While it is understood that this fusion activates tyrosine kinase signaling, the mechanisms of transformation and importance of perturbation of EBF1 activity remain unknown. EBF1 is a nuclear transcription factor required for normal B-lineage specification, commitment and development. Conversely, PDGFRB is a receptor tyrosine kinase that is normally repressed in lymphocytes, yet PDGFRB remains a common fusion partner in leukemias. Here, we demonstrate that the EBF1-PDGFRB fusion results in loss of EBF1 function, multimerization and autophosphorylation of the fusion protein, activation of signal transducer and activator of transcription 5 (STAT5) signaling and gain of interleukin-7 (IL-7)-independent cell proliferation. Deregulation and loss of EBF1 function is critically dependent on the nuclear export activity of the transmembrane (TM) domain of PDGFRB. Deletion of the TM domain partially rescues EBF1 function and restores IL-7 dependence, without requiring kinase inhibition. Moreover, we demonstrate that EBF1-PDGFRB synergizes with loss of IKAROS function in a fully penetrant B-ALL in vivo. Thus, we establish that EBF1-PDGFRB is sufficient to drive leukemogenesis through TM-dependent loss of transcription factor function, increased proliferation and synergy with additional genetic insults including loss of IKAROS function.

[Coronary stent thrombosis: what's new in 2011?]. / Koronare Stent-Thrombosen : Was gibt es Neues für 2011?

Stent thrombosis (ST) is a serious complication of percutaneous coronary interventions (PCI) with high mortality rates of up to 45%. Bare metal stents (BMS) and drug-eluting stents (DES) present similar rates of early (0.6%-1.2%) and late (0.3%-0.4%) ST. Very late ST is a specific entity after implantation of first-generation DES (sirolimus and paclitaxel) with an observed rate at 0.6% events/year. Strong predictors for early and late ST include: inadequate platelet inhibition, acute coronary syndromes (ACS), procedure-related factors such as stent underexpansion or dissection and patient-related factors such as diabetes, renal failure or a low left ventricular ejection fraction. Very late ST has been associated with delayed endothelial healing and drug-induced hypersensitivity reaction with exaggerated positive vessel remodeling, secondary incomplete stent apposition and paradoxical vasoconstriction. Dual antiplatelet therapy plays a key role in the prevention of ST. Premature dual antiplatelet therapy interruption (<6 months after PCI) and clopidogrel resistance (25% of patients) are strongly associated with ST. Finally, promising new pharmacologic agents such as prasugrel and ticagrelor have been introduced, permitting more predictable inhibition of platelet aggregation and enabling a further reduction in ST risk.

Regulation of in vitro and in vivo immune functions by the cytosolic adaptor protein SKAP-HOM.

SKAP-HOM is a cytosolic adaptor protein representing a specific substrate for the Src family protein tyrosine kinase Fyn. Previously, several groups have provided experimental evidence that SKAP-HOM (most likely in cooperation with the cytosolic adaptor protein ADAP) is involved in regulating leukocyte adhesion. To further assess the physiological role of SKAP-HOM, we investigated the immune system of SKAP-HOM-deficient mice. Our data show that T-cell responses towards a variety of stimuli are unaffected in the absence of SKAP-HOM. Similarly, B-cell receptor (BCR)-mediated total tyrosine phosphorylation and phosphorylation of Erk, p38, and JNK, as well as immunoreceptor-mediated Ca(2+) responses, are normal in SKAP-HOM(-/-) animals. However, despite apparently normal membrane-proximal signaling events, BCR-mediated proliferation is strongly attenuated in the absence of SKAP-HOM(-/-). In addition, adhesion of activated B cells to fibronectin (a ligand for beta1 integrins) as well as to ICAM-1 (a ligand for beta2 integrins) is strongly reduced. In vivo, the loss of SKAP-HOM results in a less severe clinical course of experimental autoimmune encephalomyelitis following immunization of mice with the encephalitogenic peptide of MOG (myelin oligodendrocyte glycoprotein). This is accompanied by strongly reduced serum levels of MOG-specific antibodies and lower MOG-specific T-cell responses. In summary, our data suggest that SKAP-HOM is required for proper activation of the immune system, likely by regulating the cross-talk between immunoreceptors and integrins.

Accuracy and reproducibility of coronary flow rate assessment by real-time contrast echocardiography: in vitro and in vivo studies.

Real-time myocardial contrast echo (MCE) provides the potential to assess myocardial blood flow from time-intensity refilling curves after high-energy bubble destruction. This study validated the accuracy of this approach and the effect of specific examination variables and instrument settings on results. The effects of examination depth and angle as well as dynamic range, pulse repetition frequency, and line density were assessed with the use of in vitro incremental flow rates produced in an in vitro tissue phantom. In vivo recordings of real-time imaging with an infusion of a contrast agent (Optison) were obtained in 7 open-chest dogs with graded left anterior descending artery stenosis at baseline and during adenosine hyperemia, and were compared with flow probe measurements. After bubble destruction, time-intensity data were fitted to an exponential function, and the rate of intensity increase (b) and peak plateau intensity (A) were derived from refilling curves. In vivo real-time values for b, but not A, correlated closely with flow probe measures (r = 0.93). A similar correlation for b was observed in vitro (r = 0.98). The correlation between flow rate and b was influenced by several examination variables, including depth, angle, and instrument settings. Real-time MCE provides accurate quantification of coronary flow by assessing the rate of microbubble refilling. However, this parameter may be affected by several examination and instrument variables. Therefore, real-time MCE refilling measures are best applied by comparing baseline values with those of stress studies.

Comparative value of dobutamine and adenosine stress in the detection of coronary stenosis with myocardial contrast echocardiography.

BACKGROUND: Controversy continues as to whether adenosine or dobutamine is the superior pharmacological stress agent for myocardial contrast echocardiography (MCE). METHODS AND RESULTS: We compared real-time MCE refilling curves and wall thickening during adenosine and dobutamine stress in 14 open-chest dogs with left anterior descending and left circumflex coronary artery stenoses that reduced hyperemia by 40% to 60% and 70% to 90% (mild and severe non-flow-limiting stenosis, NFLS) and resting flow by 10% to 30% and 35% to 50% (mild and severe flow-limiting stenosis, FLS). MCE was performed with low-energy imaging during Optison infusion. After high-energy bubble destruction, time-intensity data from risk beds were fitted for an exponential function as y=A(1-e(-)(bt)), from which the rate of intensity increase (b) and maximal plateau intensity (A) were derived. Although severe NFLS and greater stenoses decreased b with both dobutamine and adenosine, with mild NFLS it was reduced in 58% of animals with dobutamine versus 8% with adenosine. The absolute decrease in b, however, was greater for adenosine than dobutamine with FLS. The A parameter was decreased with both adenosine and dobutamine only with the most severe FLS. Wall thickening was decreased with dobutamine in 33% of animals with severe NFLS and in all animals with any FLS; with adenosine, in all with severe FLS. CONCLUSIONS: Both dobutamine and adenosine significantly reduce MCE refilling rates in the setting of severe stenosis and in the absence of contractile abnormalities. Dobutamine decreases refilling rate and wall thickening at a less reduced flow grade than adenosine, but adenosine produces a greater magnitude of change than dobutamine.

Heterozygous defect in HIV-1 coreceptor CCR5 and chemokine production.

CC chemokine receptor 5 (CCR5) is a cell entry cofactor for macrophage-tropic isolates of human immunodeficiency virus 1 (HIV-1). An inactive CCR5 allele with a 32-nucleotide deletion (CCR5Delta32) has been described that confers resistance to HIV-1 infection in homozygotes and slows the rate of progression to AIDS in heterozygotes. We found the allele CCR5Delta32 to be not rare in 399 Swiss blood donors with a frequency of 0.080. To assess the influence of defective CCR5 on production of its ligands we determined the capacity to produce the chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and RANTES in comparison with the production of the CXC chemokine IL-8 which does not bind to CCR5. Production of chemokines was determined during endotoxin stimulation of whole-blood samples ex vivo. Both, basal and LPS-induced chemokine production in 32 blood donors heterozygous for CCR5Delta32 were not significantly different when compared with 55 blood donors who were homozygous for the wild type CCR5 allele.

Neural and endogenous catecholamines in the bone marrow. Circadian association of norepinephrine with hematopoiesis?

Members of our research team have recently reported that adrenergic agents may affect hematopoiesis via alpha1-adrenoceptors present on bone marrow B cell precursors. In this paper we demonstrate that murine bone marrow contains a substantial amount of catecholamines. Norepinephrine (NE) and dopamine (DA) exhibited a daily rhythmicity, with peak values observed during the night. The rhythm was disrupted by chemical sympathectomy, whereas epinephrine (E) showed no rhythmicity or sensitivity to 6-hydroxydopamine. High and low values of NE and DA were associated with high and low values of their metabolites, which indicated a rhythmic catecholamine release. NE, but not DA or E, was positively associated with the proportion of cells in the G2/M and S phases of the cell cycle. Moreover, NE and DA were found in both short-term and long-term bone marrow cultures as well as in human or murine B lymphoid cell lines. These findings indicate that endogenous catecholamines in the bone marrow have both neural and cellular origins. The neural input shows a daily rhythm and may be implicated in the regulation of hematopoiesis.

[Reversible posterior leukoencephalopathy: significance in everyday clinical practice]. / Reversible posteriore Leukoenzephalopathie: Bedeutung im klinischen Alltag.

Reversible posterior leukoencephalopathy (PLE) is a newly recognized syndrome with characteristic radiologic findings. The clinical picture resembles that of hypertensive encephalopathy. PLE is caused by uncontrolled hypertension as well as other neurotoxic conditions. We report on 3 patients with this syndrome. One patient also had transient hydrocephalus which may have been caused by PLE. Clinicians must be aware of this syndrome as its recognition obviates unnecessary diagnostic procedures. PLE is reversible by lowering elevated blood pressure and treating neurotoxic conditions such as uremia.

Norepinephrine protects mice from acute lethal doses of carboplatin.

We demonstrated in previous studies that adrenergic agents may affect hematopoiesis via high- and low-affinity alpha1-adrenoceptors present on bone marrow (BM) cells [1-3]. Here we show that norepinephrine administration in mice rescued hematopoiesis from the toxic effect of the non-cell cycle specific chemotherapeutic agent, carboplatin. Protection of granulocyte/macrophage colony-forming units (GM-CFUs) was already apparent only a few hours after carboplatin and norepinephrine administration. On day 3, hematopoietic rescue was reflected by higher leukocyte and platelet counts. At its most effective dose (3 mg/kg, subcutaneously injected), norepinephrine protected 77% of the mice previously injected intravenously with 200 mg/kg of carboplatin (LD 100: 170 mg/kg). Simultaneous administration of the alpha1-adrenoceptor antagonist prazosin reduced the percentage of surviving mice to 30%, indicating that alpha1-adrenoceptors mediated most of the norepinephrine-induced hematopoietic rescue. Consistently, prazosin administration also reduced blood counts and GM-CFUs. In vitro, norepinephrine (1 microM) rescued GM-CFUs in BM cells, although this effect was counteracted by low concentrations (0.1-10 nM) of prazosin. Our findings indicate a previously undescribed novel mechanism of hematopoietic regulation and may find application in preventing the myeloablative effect of anticancer treatments.

Hematopoietic rescue in mice via alpha 1-adrenoceptors on bone marrow B cell precursors.

We demonstrated that adrenergic agents may affect hematopoiesis via high and low affinity al-adrenergic receptors (alpha 1-ARs) present on bone marrow cells. Here we show that the high affinity, alpha 1-AR is present on Mac1(-) B220(+)sIgM(-) (pre-B) cells. The low affinity alpha 1-AR seems to be present on Mac1(+) B220(-) cells. Noradrenaline administration in mice rescued hematopoiesis from the toxic effect of carboplatin or X-rays sublethal irradiation. The protection was reflected by higher leukocyte and platelets counts as well as by increased bone marrow granulocyte/macrophage colony-forming units (GM-CFU). At its most effective dose (3 mg/kg, s.c.), noradrenaline protected 77% of the mice injected i.v. with 200 mg/kg of carboplatin (LD 100:170 mg/kg). The contemporary administration of the alpha 1-AR antagonist prazosin brought the percent of surviving mice down to 30% indicating that alpha 1-ARs mediated most of the noradrenaline-induced hematopoietic rescue. In vitro, noradrenaline (1 mu M) rescued GM-CFU in unseparated bone marrow cells containing the adherent population expressing the high affinity alpha 1-AR. Consistently, the hematopoietic rescue was counteracted by low concentrations (0.1 nM-10 nM) of the alpha 1-antagonist prazosin. Our findings describe a novel mechanism of hematopoietic regulation and might find application in preventing the myeloablative effect of anticancer treatments.

Rapid diagnosis of pancreatic cancer by combination of ultrasonography and serum tumour markers CA 19-9 and CA 50.

Non-invasive tests such as ultrasonography (US) and serum CA 19-9 or CA 50 present substantial sensitivity, but are not devoid of false-negative results in the diagnosis of pancreatic cancer. The patient sample in this study comprised 58 patients, 51 with adenocarcinoma, 4 with cystadenocarcinoma, 2 with islet-cell carcinoma and 1 with anaplastic carcinoma. All the patients underwent US examination with evaluation of visible tumour volume by means of the sphere or ellipsoid rotation formula. Serum CA 19-9 was measured in all cases, and CA 50 in 50. Pancreatic tumours were diagnosed by US in 47/58 patients [sensitivity (S) = 81.03%] and ductal carcinomas in 46/55 (S = 83.6%). Abnormal CA 19-9 values were found in 48/58 subjects (S = 82.7%) and in 47/55 ductal carcinomas (S = 85.4%). CA 50 showed abnormal values in 39 of the 50 tumours assessed (S = 78%) and in 38/47 ductal carcinomas (S = 80.8%). Combined use of the tests considerably improves these sensitivities. It is concluded that US results can be improved when combined with the two antigen assays. The poor correlation between tumour mass and serum antigen levels is compensated for by the US performance. The combination of US plus CA 19-9 and CA 50 provides a very good tool for the rapid non-invasive diagnosis of pancreatic cancer.