Spliceosomal gene aberrations are rare, coexist with oncogenic mutations, and are unlikely to exert a driver effect in childhood MDS and JMML

Somatic mutations of the spliceosomal machinery occur frequently in adult patients with myelodysplastic syndrome (MDS). We resequenced SF3B1, U2AF35, and SRSF2 in 371 children with MDS or juvenile myelomonocytic leukemia. We found missense mutations in 2 juvenile myelomonocytic leukemia cases and in 1 child with systemic mastocytosis with MDS. In 1 juvenile myelomonocytic leukemia patient, the SRSF2 mutation that initially coexisted with an oncogenic NRAS mutation was absent at relapse, whereas the NRAS mutation persisted and a second, concomitant NRAS mutation later emerged. The patient with systemic mastocytosis and MDS carried both mutated U2AF35 and KIT in a single clone as confirmed by clonal sequencing. In the adult MDS patients sequenced for control purposes, we detected previously reported mutations in 7/30 and a novel SRSF2 deletion (c.284_307del) in 3 of 30 patients. These findings implicate that spliceosome mutations are rare in pediatric MDS and juvenile myelomonocytic leukemia and are unlikely to operate as driver mutations.     

Autologous lymphocytes inhibit hemopoiesis in long-term culture in patients with myelodysplastic syndrome

OBJECTIVE: The current therapy of myelodysplastic syndrome (MDS) is unsatisfactory and comprises mainly supportive treatment or antileukemic chemotherapy. Recent studies about successful immunosuppressive therapy suggest an autoimmune mechanism in subtypes of myelodysplastic syndrome. PATIENTS AND METHODS: To investigate this hypothesis, bone marrow mononuclear cells (MNC) from 15 patients with low-grade MDS, refractory anemia, and refractory anemia with ringed sideroblasts (RA and RARS), and from 7 normal donors were depleted of CD2(+), CD5(+), and CD7(+) lymphocytes using magnetic cell sorting. Depleted and nondepleted MNC were seeded onto irradiated allogeneic bone marrow stroma and the generation of colony-forming-cells (CFC), the clonal origin of hemopoietic progenitor cells in long-term bone marrow culture (LTC), was compared. RESULTS: The capacity of MNC from 7 healthy donors to generate hemopoiesis remained unchanged in the lymphocyte-depleted LTC. In contrast, cultures initiated with lymphocyte-depleted MNC from patients with RA and RARS exhibited a significantly increased generation of CFC compared with the corresponding nondepleted cultures. Microsatellite analysis in 6 patients revealed that a significantly increased number of CFC grown in lymphocyte-depleted LTC showed no allelic loss, suggesting an outgrowth of normal hemopoietic cells. CONCLUSION: These results provide a rationale for the recently described successful treatment of MDS with immunosuppressive therapy. We suggest that in certain subtypes of MDS the residual normal hemopoiesis is suppressed by autoimmune mechanisms, eventually allowing the expansion of the abnormal clone.     

Renal effects of human urotensin-II in rats with experimental congestive heart failure.

BACKGROUND: Urotensin II (U-II) and its receptor GPR-14 are expressed in the kidney and the cardiovascular system of various mammalian species. Recent studies suggested that the U-II/GPR-14 system is upregulated in patients with congestive heart failure (CHF). However, the involvement of the peptide in the alterations of renal function in CHF remains unknown. METHODS: The effects of incremental doses (1.0-100.0 nmol/kg) of human U-II (hU-II) on renal haemodynamic and clearance parameters were assessed in rats with an aorto-caval fistula, an experimental model of CHF, and sham controls. Additionally, the effects of pre-treatment with the nitric oxide (NO) synthase blocker, nitro-L-arginine methyl ester (L-NAME), and the cyclooxygenase inhibitor, indomethacin, on the renal haemodynamic response to hU-II were studied in CHF rats. RESULTS: hU-II caused a decrease in mean arterial pressure in control and CHF rats. In controls, hU-II did not alter renal blood flow (RBF), and caused a minimal decrease (-12.5%) in renal vascular resistance (RVR). However, in CHF rats, the peptide induced a marked increase in RBF (+28%) and a decrease in RVR (-21.5%). These effects were attenuated by L-NAME, but not by indomethacin. Furthermore, hU-II caused a significant increase (+29%) in glomerular filtration rate (GFR) in CHF rats, whereas GFR tended to decrease in controls. Sodium excretion was not altered in control or in CHF rats in response to hU-II. CONCLUSIONS: hU-II exerts an NO-dependent renal vasodilatation that is more pronounced in rats with CHF. The data further suggest that the U-II/GPR-14 system may be involved in the regulation of renal haemodynamics in CHF.     

Alendronate-loaded nanoparticles deplete monocytes and attenuate restenosis.

Systemic transient depletion of monocytes and macrophages by liposome-encapsulated bisphosphonates (BPs), reduces neointimal formation in experimental restenosis. The aim of this study was to examine the antirestenotic effect of a polymeric nanoparticulate formulation containing the BP alendronate (ALN). The BP was successfully formulated in polylactide-co-glycolide (PLGA) nanoparticles (NP). ALN NP with negative charge, size of 223+/-64 nm, and high entrapment efficiency (55.1%) have been formulated. ALN NP exhibited a significant cytotoxic effect, in a dose-response relationship, on macrophage-like RAW264 cells in cell culture. Subcutaneously (SC) administrated ALN NP (1.5 mg/kg on days -1 and +6) resulted in a significant attenuation of neointima to media ratio (N/M) by 52.7% and stenosis by 39.7% 28 days after balloon injury in the hypercholesterolemic rabbit model. Moreover, a good correlation was found between macrophage abundance in the injured arteries and the extent of stenosis. ALN NP treatment resulted in the reduction of both interleukin-1beta and matrix metalloproteinases (2 and 9). It is concluded that a particulated dosage form of polymeric NP loaded with ALN reduce neointimal formation in vivo by systemic transient depletion of monocytes.     

Bosentan improves renal regional blood flow in rats with experimental congestive heart failure

The effects of the mixed endothelin receptor antagonist bosentan on renal regional haemodynamics were investigated in rats with aorto-caval fistula, an experimental model of congestive heart failure. A matched group of normal rats served as control. Injection of bosentan (10 mg/kg i.v.) to the rats with decompensated congestive heart failure produced an increase in cortical (+20%) and medullary (+12%) blood flow, and a decrease in vascular resistance in the cortex (−30%) and medula (−23%), while reducing mean arterial pressure by approximately 10 mm Hg. In rats with compensated congestive heart failure and in normal animals, infusion of bosentan did not affect blood pressure and cortical perfusion. These findings indicate that 1) endothelin receptor blockade produces beneficial effects on renal haemodynamics in rats with experimental congestive heart failure and 2) endothelin-1 may be involved in the pathogenesis of renal hypoperfusion only in decompensated congestive heart failure.     

Posterior fossa lesions in childhood and infancy

Forty-three children with CT studies demonstrating abnormalities in the posterior fossa are presented. Tumors constitute the largest group of lesions (53.5%). Their mean size at time of diagnosis was 39.5 mm. Astrocytomas, medulloblastomas, and ependymomas were the most frequent tumors and their CT features are described and discussed. The congenital group of lesions comprised 18.6% of the cases — the most frequent anomaly being arachnoid cyst. In the miscellaneous group (23.3%), cases with atrophy were the most frequent. The cerebellar hemispheres were the most involved sites (39.5%). Lesions located at the tentorial hiatus or near the clivus were rather rare.     

The role of advanced MR methods in the diagnosis of cerebral amyloidoma

Amyloidoma is a term referring to a tumor-like deposition of extracellular insoluble fibrillar protein. Tumor-like amyloid formation in the brain had been described in isolated cases. However no advanced radiological studies to characterize these lesions have been reported. In the report, we have describe a 59-year-old woman, presented several months prior to diagnosis with memory decline, dizziness, walking instability, and speech difficulties. MRI revealed a left basal ganglia lesion with an intraventricular component. The patient underwent a stereotactic biopsy, which confirmed the diagnosis of amyloidoma, an extensive radiographic characterization of amyloidoma using advanced MR techniques was done, including magnetic resonance spectroscopy, dynamic susceptibility contrast, susceptibility weighted image (SWI), and magnetization transfer (MTR). All advanced MR techniques were able to characterize the amyloidoma as a non-neoplastic process. This is an example where such methods can be used for differential diagnosis of atypical brain lesions.     

TYPE I GAUCHER DISEASE IN CHILDREN WITH AND WITHOUT ENZYME THERAPY

This retrospective study describes the course of 56 children with non-neuronopathic Gaucher disease who presented at <16 years and were followed at 6- to 12-month intervals for 3-9 years. Massive splenomegaly and height retardation marked those who required treatment. Enzyme replacement significantly increased hemoglobin levels; platelet counts were divergent at presentation and follow-up, regardless of therapy. Among treated patients there was a significant reduction in liver and spleen index volumes, and a significant increase in height z-scores. None of the children required splenectomy or developed lung involvement. Many patients diagnosed due to large-scale screening were very mildly affected and remain untreated.     

Disease severity in sibling pairs with type 1 Gaucher disease

The only prognostic markers in Gaucher disease, the most common lysosomal storage disorder, are young age at first symptom/sign and the presence of null/severe mutations, both being predictive of more severe phenotypes. Therefore, it would be helpful to know whether siblings with the same genotype can be expected to experience comparable phenotypic expression. All non-neuronopathic sibling pairs in our referral clinic (1993–2008) with the same genotype were included. For each pair, gender, date of birth, severity score index at presentation, age at diagnosis and first symptom/sign, presence of bone involvement, spleen status, and use of enzyme replacement therapy were tabulated. There were 90 pairs of siblings: two sets of identical twins; 24 pairs of brothers, 24 pairs of sisters, and 42 pairs of mixed gender. For all measures of disease severity used, only in sibling pairs with an older sister and a younger brother were phenotypes significantly different between siblings. Thus, this large cohort of sibling pairs with type 1 Gaucher disease confirmed that, in general, the phenotypic expression in the younger sibling will be similar enough to that of an older affected sibling that genetic counseling may use those findings in a prognostic way.