CALR,JAK2 and MPL mutation status in Argentinean patients with BCR-ABL1- negative myeloproliferative neoplasms

Objectives: To establish the frequency of JAK2, MPL and CALR mutations in Argentinean patients with BCR-ABL1-negative myeloproliferative neoplasms (MPN) and to compare their clinical and haematological features.

Methods: Mutations of JAK2V617F, JAK2 exon 12, MPL W515L/K and CALR were analysed in 439 Argentinean patients with BCR-ABL1-negative MPN, including 176 polycythemia vera (PV), 214 essential thrombocythemia (ET) and 49 primary myelofibrosis (PMF).

Results: In 94.9% of PV, 85.5% ET and 85.2% PMF, we found mutations in JAK2, MPL or CALR. 74.9% carried JAK2V617F, 12.3% CALR mutations, 2.1% MPL mutations and 10.7% were triple negative. In ET, nine types of CALR mutations were identified, four of which were novel. PMF patients were limited to types 1 and 2, type 2 being more frequent.

Discussion: In ET, patients with CALR mutation were younger and had higher platelet counts than those with JAK2V617F and triple negative. In addition, JAK2V617F patients had high leucocyte and haemoglobin values compared with CALR-mutated and triple-negative patients. In PMF, patients with mutant CALR were associated with higher platelet counts.

Conclusion: Our study underscores the importance of JAK2, MPL and CALR genotyping for accurate diagnosis of patients with BCR-ABL1-negative MPN.     

Meta-analysis identifies mitochondrial DNA sequence variants associated with walking speed

Declines in walking speed are associated with a variety of poor health outcomes including disability, comorbidity, and mortality. While genetic factors are putative contributors to variability in walking, few genetic loci have been identified for this trait. We examined the role of mitochondrial genomic variation on walking speed by sequencing the entire mitochondrial DNA (mtDNA). Data were meta-analyzed from 1758 Lifestyle Interventions and Independence for Elders (LIFE) Study and replication data from 730 Health, Aging, and Body Composition (HABC) Study participants with baseline walking speed information. Participants were 69+?years old of diverse racial backgrounds (African, European, and other race/ethnic groups) and had a wide range of mean walking speeds [4–6 m (0.78–1.09 m/s) and 400 m (0.83–1.24 m/s)]. Meta-analysis across studies and racial groups showed that m.12705C>T, ND5 variant was significantly associated (p?<?0.0001) with walking speed at both short and long distances. Replication and meta-analysis also identified statistically significant walking speed associations (p?<?0.0001) between the m.5460.G>A, ND2 and m.309C>CT, HV2 variants at short and long distances, respectively. All results remained statistically significant after multiple comparisons adjustment for 499 mtDNA variants. The m.12705C>T variant can be traced to the beginnings of human global migration and that cells carrying this variant display altered tRNA expression. Significant pooled effects related to stopping during the long-distance walk test were observed across OXPHOS complexes I (p?=?0.0017) and III (p?=?0.0048). These results suggest that mtDNA-encoded variants are associated with differences in walking speed among older adults, potentially identifying those at risk of developing mobility impairments.     

VEGF signaling on hematopoietic precursors restricts B-lymphoid commitment in vitro and in vivo

Vascular endothelial growth factor (VEGF) signals on vascular and hematopoietic cells via its receptors, VEGFR-2 (KDR) and VEGFR-1 (FLT-1). Elevated levels of VEGF, such as during tumor growth or inflammation, have been suggested to suppress hematopoiesis; most studies refer to KDR as the main receptor involved in this inhibitory effect. In the present study, having detected expression of FLT-1 in B-lymphoid precursors, we exploited the possibility that VEGF signaling via FLT-1 might affect early B-cell commitment. Using a well-established in vitro B-cell differentiation assay, we demonstrate that FLT-1 blockade promotes B-cell commitment and subsequent differentiation, while KDR blockade has no effect on B-cell commitment. In agreement, in vivo transplantation of human (CD34+) or murine (Sca1+l/Lin-) FLT-1-negative hematopoietic precursors into irradiated severe combined immune-deficient mice restored the bone marrow lymphoid compartment, while transplanting the FLT-1-positive counterpart failed to repopulate the lymphoid compartment, and unexpectedly resulted in early death of the irradiated recipients due to hematopoietic suppression. Taken together, we suggest that VEGF signaling via FLT-1 on hematopoietic precursors may restrict lymphopoiesis.     

High accuracy of bilateral and simultaneous petrosal sinus sampling with desmopressin for the differential diagnosis of pediatric ACTH-dependent Cushing’s syndrome

Pituitary - To analyze the bilateral and simultaneous petrosal sinus sampling (BIPSS) in a subgroup of children and adolescents with ACTH-dependent Cushing’s syndrome (ADCS) Retrospective...     

Postmortem Characterization of Patients With Clinical Diagnosis of Plasmodium vivax Malaria: To What Extent Does This Parasite Kill?

Background.?Severe disease attributable to Plasmodium vivax infection is already well described worldwide; however, autopsies in these patients are scarce. Methods.?From 1996 to 2010, 19 patient deaths with a clinical diagnosis of P. vivax infection occurred in a tertiary care center in the Brazilian Amazon. Seventeen of these 19 deaths were fully autopsied. Clinical charts, macroscopic autopsy reports, and stored paraffinized tissue blocks were retrieved. Nested polymerase chain reaction was performed in paraffinized samples of spleen and lung to confirm P. vivax monoinfection. Immunohistofluorescence was used to detect P. vivax parasitized red blood cells (RBCs). Results.?Of 17 autopsies, 13 revealed that death could be attributed to P. vivax infection; in the remaining 4, acute diseases other than malaria were found to be the cause of death. The primary complication in patients in which malaria contributed to death was acute respiratory distress syndrome (ARDS) and pulmonary edema associated with the accumulation of neutrophils in the interalveolar space (6 cases). Spleen rupture (3 cases) and multiorgan dysfunction syndrome (3 cases) were the second most common complications. One child evolving with coma was also characterized, but no parasite was detected in the brain tissue. In one patient who developed ARDS and presented negative peripheral parasitemia by the time of death, scattered parasitized red blood cells were seen inside pulmonary capillaries, suggesting some sequestration in the lung. Conclusions.?In 13 of 17 deceased patients, P. vivax infection was the plausible cause of death. However, more studies are needed to understand pathogenesis related to severe disease.