Chk2 drives late G1/early S phase arrest of clonal myeloid progenitors expressing the p210 BCR-ABL tyrosine kinase in response to STI571

STI571 is the most innovative drug for the cure of Chronic Myeloid Leukemia. It inhibits, in fact, the disease causative event, the p210 bcr-abl tyrosine kinase, and addresses clonal myeloid progenitors to apoptotic death. Here, we demonstrated that STI571 also induces growth arrest by activating the Chk2-Cdc25A-Cdk2 axis, a pathway complementary to p53 in the activation of G(1)/S cell cycle checkpoint. In vitro exposure to STI571 of 32D murine myeloid progenitor cell clones transducing a temperature-sensitive p210 bcr-abl construct was associated with Chk2 phosphorylation and activation, Cdc25A degradation and persistent Cdk2 inhibitory phosphorylation, preventing, in turn, cell transition to and progression throughout the S phase of cell cycle. Chk2 and Cdc25A are both components of a complex network that integrates signals involved in regulated cell cycle progression, DNA repair and cell decision between life or death. Chk2 gene mutations or decreased expression, leading to its protein loss of function on Cdc25A target, and Cdc25A overexpression have been linked to poor prognosis of human cancers. In CML, they might further enhance the proliferative advantage and genomic instability of clonal myeloid progenitors featuring a class of poor prognosis patients eventually resistant to STI571.     

Gadolinium magnetic angioresonance in the study of aortoiliac disease

There is a need for noninvasive methods for the early identification of patients with intermittent claudication who need surgical treatment. Newer magnetic resonance angiography (MRA) techniques allow detailed study of the arterial tree with image quality similar to that of conventional arteriography. From April 1997 to January 2001, 30 patients with intermittent claudication of the lower limbs were studied with both imaging methods. In each case, the MRA images were examined first and the arteriographic images were examined 15 days later. Examiners interpreting the arteriographic images were blinded to the results of the corresponding MRA images. After each examination (MRA and arteriography), a vascular surgeon suggested a surgical plan. MRA showed results similar to those of arteriography, although with inferior image quality. No patient had an allergic reaction or side effects due to administration of contrast material. There was total agreement between MRA and arteriography in regard to the morphologic analysis and proposed surgical plans in every case. In conclusion, MRA is a feasible, useful, and less invasive alternative for the morphologic evaluation of the aortofemoral area in patients with intermittent claudication of lower limbs.     

Accumulation of catalytically active PKC-ζ into the nucleus of HL-60 cell line plays a key role in the induction of granulocytic differentiation mediated by all-trans retinoic acid

The effect of differentiating doses of all- trans retinoic acid (ATRA, 10⁻⁶  m ) and vitamin D3 (10⁻⁷  m ) was investigated on the nuclear levels of endogenous ceramide and protein kinase C-ζ (PKC-ζ) catalytic activity in HL-60 myeloid cells. ATRA induced a parallel increase of ceramide and catalytically active PKC-ζ into the nuclear compartment of HL-60 cells (peak at 72 h). On the other hand, vitamin D3 increased the levels of nuclear ceramide and PKC-ζ activity to a lesser extent and with a delayed kinetics compared to ATRA (peak at 96 h).
Pretreatment of HL-60 cells with high pharmacological concentrations of exogenously-added C₂-ceramide (10⁻⁶  m ) completely blocked the ATRA-mediated activation of nuclear PKC-ζ. Exogenous C₂-ceramide (10⁻⁶  m ) also inhibited the granulocytic differentiation induced by ATRA, whereas it did not affect monocytic differentiation mediated by vitamin D3.
Transient transfection experiments performed with a plasmid construct containing a constitutively active mutated form of the PKC-ζ cDNA fused in 3' to a fluorescent tag protein (pEGFP-PKC-ζ) demonstrated that the overexpression of catalytically active PKC-ζ was not accompanied by the appearance of a differentiated morphology. These findings suggest that nuclear PKC-ζ is necessary but not sufficient to induce granulocytic differentiation of HL-60 myeloid malignant cells.     

Neuroadrenergic denervation of the lung in type I diabetes mellitus complicated by autonomic neuropathy

STUDY OBJECTIVE: To verify whether autonomic neuropathy (AN) complicating type I, insulin-dependent diabetes mellitus affected neuroadrenergic bronchopulmonary innervation. PATIENTS: Twenty nonsmoking diabetic patients without respiratory diseases were studied: 11 patients with AN (group AN) and 9 patients without AN (control; group C) diagnosed by standardized criteria. DESIGN: Patients underwent respiratory function tests and ventilatory scintigraphies with (123)I-metaiodobenzylguanidine (MIBG) and with (99m)Tc-diethylenetriaminepenta-acetic acid (DTPA) to assess both bronchopulmonary neuroadrenergic innervation and also permeability of the alveolar-capillary barrier to water-soluble tracers. Rates of pulmonary clearance of the two tracers were computed, and correlates were identified by nonparametric statistics. SETTING: University hospital. RESULTS: The AN and C groups had normal respiratory function test results and comparable duration of diabetes and quality of metabolic control. (99m)Tc-DTPA clearance did not distinguish the groups. (123)I-MIBG clearance was faster in the AN group than in the C group (mean +/- SD half-time of the radiotracer time-activity curve [T(1/2)], 116.1 +/- 22.8 min in the AN group vs 139.5 +/- 18.3 min in the C group, p = 0.022), which is consistent with neuroadrenergic denervation in the AN group. (123)I-MIBG clearance was independent from (99m)Tc-DTPA clearance. Faster (123)I-MIBG clearance was significantly associated with worse performance in three of the four autonomic tests. CONCLUSIONS: Neuroadrenergic bronchopulmonary denervation may occur in diabetic patients with AN despite normal clinical and respiratory function findings. Further research is needed to identify clinical and prognostic implications of these findings.     

Electrocardiographic Diagnosis of Atrial Tachycardia: Classification,P‐Wave Morphology,and Differential Diagnosis with Other Supraventricular Tachycardias

Atrial tachycardia is defined as a regular atrial activation from atrial areas with centrifugal spread, caused by enhanced automaticity, triggered activity or microreentry. New ECG classification differentiates between focal and macroreentrant atrial tachycardia. Macroreentrant atrial tachycardias include typical atrial flutter and other well characterized macroreentrant circuits in right and left atrium. Typical atrial flutter has been described as counterclockwise reentry within right atrial and it presents a characteristic ECG “sawtooth” pattern on the inferior leads. The foci responsible for focal atrial tachycardia do not occur randomly throughout the atria but tend to cluster at characteristic anatomical locations. The surface ECG is a very helpful tool in directing mapping to particular areas of interest. Atrial tachycardia should be differentiated from other supraventricular tachycardias. We propose a diagnostic algorithm in order to help the physician to discriminate among those. Holter analysis could offer further details to differentiate between atrial tachycardia and another supraventricular tachycardia. However, if the diagnosis is uncertain, it is possible to utilize vagal maneuvers or adenosine administration. In conclusion, in spite of well–known limits, a good interpretation of ECG is very important and it could help the physician to manage and to treat correctly patients with atrial tachycardia.     

A genetic score for the prediction of beta-thalassemia severity

Clinical and hematologic characteristics of beta(β)-thalassemia are determined by several factors resulting in a wide spectrum of severity. Phenotype modulators are: HBB mutations, HBA defects and fetal hemoglobin production modulators (HBG2:g.−158C>T polymorphism, HBS1L-MYB intergenic region and the BCL11A). We characterized 54 genetic variants at these five loci robustly associated with the amelioration of beta-thalassemia phenotype, to build a predictive score of severity using a representative cohort of 890 β-thalassemic patients. Using Cox proportional hazard analysis on a training set, we assessed the effect of these loci on the age at which patient started regular transfusions, built a Thalassemia Severity Score, and validated it on a testing set. Discriminatory power of the model was high (C-index=0.705; R²=0.343) and the validation conducted on the testing set confirmed its predictive accuracy with transfusion-free survival probability (P<0.001) and with transfusion dependency status (Area Under the Receiver Operating Characteristic Curve=0.774; P<0.001). Finally, an automatized on-line calculation of the score was made available at http://tss.unica.it. Besides the accurate assessment of genetic predictors effect, the present results could be helpful in the management of patients, both as a predictive score for screening and a standardized scale of severity to overcome the major-intermedia dichotomy and support clinical decisions.     

Bortezomib‐based therapy combined with high cut‐off hemodialysis is highly effective in newly diagnosed multiple myeloma patients with severe renal impairment

Multiple myeloma (MM) is often associated with renal insufficiency (RI) which adversely influences the prognosis. Several studies demonstrated that bortezomib can improve both renal function and outcome. We prospectively evaluated 21 newly diagnosed MM patients with severe renal impairment secondary to tubular‐interstitial damage, most of them due to myeloma kidney, who were primarily treated with bortezomib‐based therapy combined with high cut‐off hemodialysis (HCOD). The median serum creatinine level at baseline was 6.44 mg dL^?1 and calculated median estimated glomerular filtration rate (eGFR), according to Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) creatinine equation, was 8 mL/min/1.73 m². Serum free light chain (sFLC) median concentration was 6,040 mg L^?1. Post induction and best stringent complete response rates were 19 and 38%, respectively. Responses were fast, occurring within a median of 1.4 months. The combination of bortezomib and HCOD led to a prompt and remarkable (>90%) decrease in sFLC levels. Sixteen patients (76%) became dialysis independent within a median of 32 days. With a median follow up of 17.2 months, the 3‐year PFS and OS were 76 and 67%, respectively. No early deaths were observed. This study demonstrates that incorporation of bortezomib into induction therapy combined with HCOD is a highly effective strategy in rescuing renal function and improving outcomes in patients with MM and RI. Am. J. Hematol. 90:647–652, 2015. © 2015 Wiley Periodicals, Inc.