Dynamic changes in the clonal structure of MDS and AML in response to epigenetic therapy.

Traditional response criteria in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are based on bone marrow morphology and may not accurately reflect clonal tumor burden in patients treated with non-cytotoxic chemotherapy. We used next-generation sequencing of serial bone marrow samples to monitor MDS and AML tumor burden during treatment with epigenetic therapy (decitabine and panobinostat). Serial bone marrow samples (and skin as a source of normal DNA) from 25 MDS and AML patients were sequenced (exome or 285 gene panel). We observed that responders, including those in complete remission (CR), can have persistent measurable tumor burden (that is, mutations) for at least 1 year without disease progression. Using an ultrasensitive sequencing approach, we detected extremely rare mutations (equivalent to 1 heterozygous mutant cell in 2000 non-mutant cells) months to years before their expansion at disease relapse. While patients can live with persistent clonal hematopoiesis in a CR or stable disease, ultimately we find evidence that expansion of a rare subclone occurs at relapse or progression. Here we demonstrate that sequencing of serial samples provides an alternative measure of tumor burden in MDS or AML patients and augments traditional response criteria that rely on bone marrow blast percentage.

Epigenomic analysis of the HOX gene loci reveals mechanisms that may control canonical expression patterns in AML and normal hematopoietic cells.

HOX genes are highly expressed in many acute myeloid leukemia (AML) samples, but the patterns of expression and associated regulatory mechanisms are not clearly understood. We analyzed RNA sequencing data from 179 primary AML samples and normal hematopoietic cells to understand the range of expression patterns in normal versus leukemic cells. HOX expression in AML was restricted to specific genes in the HOXA or HOXB loci, and was highly correlated with recurrent cytogenetic abnormalities. However, the majority of samples expressed a canonical set of HOXA and HOXB genes that was nearly identical to the expression signature of normal hematopoietic stem/progenitor cells. Transcriptional profiles at the HOX loci were similar between normal cells and AML samples, and involved bidirectional transcription at the center of each gene cluster. Epigenetic analysis of a subset of AML samples also identified common regions of chromatin accessibility in AML samples and normal CD34(+) cells that displayed differences in methylation depending on HOX expression patterns. These data provide an integrated epigenetic view of the HOX gene loci in primary AML samples, and suggest that HOX expression in most AML samples represents a normal stem cell program that is controlled by epigenetic mechanisms at specific regulatory elements.

Recurrent DNMT3A mutations in patients with myelodysplastic syndromes.

Alterations in DNA methylation have been implicated in the pathogenesis of myelodysplastic syndromes (MDS), although the underlying mechanism remains largely unknown. Methylation of CpG dinucleotides is mediated by DNA methyltransferases, including DNMT1, DNMT3A and DNMT3B. DNMT3A mutations have recently been reported in patients with de novo acute myeloid leukemia (AML), providing a rationale for examining the status of DNMT3A in MDS samples. In this study, we report the frequency of DNMT3A mutations in patients with de novo MDS, and their association with secondary AML. We sequenced all coding exons of DNMT3A using DNA from bone marrow and paired normal cells from 150 patients with MDS and identified 13 heterozygous mutations with predicted translational consequences in 12/150 patients (8.0%). Amino acid R882, located in the methyltransferase domain of DNMT3A, was the most common mutation site, accounting for 4/13 mutations. DNMT3A mutations were expressed in the majority of cells in all tested mutant samples regardless of myeloblast counts, suggesting that DNMT3A mutations occur early in the course of MDS. Patients with DNMT3A mutations had worse overall survival compared with patients without DNMT3A mutations (P=0.005) and more rapid progression to AML (P=0.007), suggesting that DNMT3A mutation status may have prognostic value in de novo MDS.

Photic-induced sensitization: acquisition of an augmenting spike-wave response in the adult rat through repeated strobe exposure.

It is well established that patterns of sensory input can affect neuroplastic changes during early development. The scope and consequences of experience-dependent plasticity in the adult are less well understood. We studied the possibility that repeated exposure to trains of stroboscopic stimuli could induce a sensitized and potentially aberrant response in ordinary individuals. Chronic electrocorticographic recording electrodes enabled measurement of responses in awake, freely moving animals. Normal adult rats, primarily Sprague-Dawley, were exposed to 20-40 strobe trains per day after a strobe-free adaptation period. The common response to strobe trains changed in 34/36 rats with development of a high-amplitude spike-wave response that emerged fully by the third day of photic exposure. Onset of this sensitized response was marked by short-term augmentation of response to successive strobe flashes. The waveform generalized across the brain, reflected characteristics of the visual stimulus, as well as an inherent 6- to 8-Hz pacing, and was suppressed with ethosuximide administration. Spike-wave episodes were self-limiting but could persist beyond the strobe period. Sensitization lasted 2-4 wk after last strobe exposure. The results indicate visual stimulation, by itself, can induce in adult rats an enduring sensitization of visual response with epileptiform characteristics. The results raise the question of the effects of such neuroplastic change on sensation and epileptiform events.

Transhepatic catheterization using ultrasound-guided access.

The efficacy and safety of ultrasound guidance to obtain transhepatic access for cardiac catheterization were investigated in this study. The transhepatic route for access to perform cardiac catheterization has become an acceptable alternative when conventional routes of access have failed. However, the use of ultrasound to guide transhepatic access has not been reported in the literature. We performed a retrospective chart review. Patient characteristics, indications for catheterization, procedures performed, and complications were recorded. All patients who underwent transhepatic cardiac catheterization at Duke University Medical Center were included in this study. Eight patients underwent 12 catheterizations. The median age was 5.3 years (range, 9 months to 13 years) and median weight 18.7 kg (range, 7.1-44.8 kg). Seven catheterizations were diagnostic and 5 were interventional. There were no complications. Transhepatic access with ultrasound guidance is a safe and effective option for obtaining venous access for cardiac catheterization.

An infant with subvalvar and valvar aortic stenosis, subvalvar and valvar pulmonary stenosis, severe biventricular hypertrophy and pulmonary hemorrhage.

An infant with subvalvar and valvar pulmonary stenosis, subvalvar, and valvar aortic stenosis and hypertrophic cardiomyopathy, who presented with pulmonary hemorrhage, is reported. He had right ventricular hypertrophy, thickened pulmonary valve leaflets, severe asymmetric left ventricular hypertrophy with outflow tract obstruction, and a thickened and dysplastic aortic valve.

Intraoperative stents to rehabilitate severely stenotic pulmonary vessels.

BACKGROUND: Patch enlargement of severe branch pulmonary artery stenosis (PAS) or pulmonary vein ostial stenosis (PVS) can be technically challenging. Recurrences are common and exposure may require long periods of cardiopulmonary bypass (CPB). METHODS: Since 1993, we performed 31 procedures on 27 patients with endovascular stents placed intraoperatively under direct surgical vision: 22 patients with tight PAS and 5 patients with PVS. Selection for intraoperative (vs catheterization laboratory) stent placement was prompted by: (1) the need for a concomitant cardiac surgical procedure (16 cases); (2) limited vascular access for catheterization laboratory stent placement (11 cases); or (3) "rescue" of patients with complications after attempted placement of stents (4 cases). RESULTS: In this group of very complex and challenging patients there were 5 hospital deaths (hospital survival, 81%). Follow-up of survivors has ranged from 1 month to 7 years (mean 2.8 +/- 1.7 years). There have been 3 late deaths (late "series" survival, 70%). No complication or death was related to stent placement. Surviving patients have had significant clinical improvement. Mean pulmonary gradient (postoperative vs preoperative echo) has fallen in all survivors and has decreased from a mean of 66 mm Hg preoperatively to 28 mm Hg postoperatively (p = 0.01). All pulmonary arteries are appreciably enlarged and will be easier to deal with at a later date if necessary. One patient (DORV, HLHS ) with pulmonary vein stents has gone on to a successful Glenn procedure. The other two surviving patients with PV stents have occlusion of their proximal PVs on follow-up catheterization; thus only 1 of 5 patients with stents for PVS has had a successful outcome. Four patients have had repeat surgery. Stents have produced no impediment to subsequent surgical procedures, and the pulmonary arteries were easy to work with. CONCLUSIONS: Intraoperative stenting provides an attractive option for "rehabilitation" of pulmonary vessels. Direct vision insertion on CPB is extremely quick and immediately effective, limiting the CPB exposure required to treat this problem. Once stented, vessels remain open and are amenable to future surgical intervention as necessary. Outcome is better for patients with PAS versus those with PVS.

Microvena atrial septal defect occlusion device--update 2000.

This article (1) summarizes the Duke University results with the Das-Angel Wings atrial septal defect occlusion device, (2) outlines the rationale for design changes in the device, and (3) describes the new Microvena atrial septal defect occlusion device characteristics, and plans for the future. At Duke University, investigators using the first-generation device attempted closures in 35 patients with atrial level communications. Ages ranged from 5 to 83 years with a median of 28 years, and weights ranged from 16 to 100 kg. Thirty-two of the 35 defects had successful device placement. On follow-up, the defects of 27 of 32 patients with an implanted device were completely closed, and 5 patients had < 2-mm residual leaks. Three patients had malposition of the device, two of whom were treated surgically and one of whom was treated with percutaneous device retrieval. Complications included one small mitral valve perforation with no clinical sequelae. There have been no strokes, delayed embolizations, nor procedure or device related deaths. There have been no new or late problems in the cohort in a follow-up extending to 63 months. Opportunities for improvement of the device were noted during the clinical study. The manufacturer, Microvena Corporation, voluntarily withdrew the occluder for a redesign initiative. The objectives of redesign were ready deployment, reduction of device manipulation, rounding of the device, and retrievability. The Guardian Angel device has been the product of the redesign effort. It is a percutaneously inserted atrial septal defect occlusion device that uses the same materials as the initial device, but which has advantages of retrievability, repositionability, and no need for device manipulation. Initial studies have been performed in experimental animals, and clinical trials are planned for the near future.

Congenital agenesis of the right pulmonary artery.

A 44-year-old woman with recurrent pulmonary infections developed severe hemoptysis. Chest radiography revealed a hypoplastic right lung. Absence of the right pulmonary artery, a very rare congenital anomaly, was demonstrated by computed tomography and cardiac catheterization. Severe pulmonary hypertension in the contralateral lung precluded right pneumonectomy but percutaneous embolization of a large systemic arterial collateral to the right lung provided palliative relief of hemoptysis.

Conceptual structure and social functions of behavior explanations: beyond person--situation attributions.

The traditional approach to studying behavior explanations involves treating them as either person causes or situation causes and assessing them by using rating scales. An analysis of people's free-response behavior explanations reveals, however, that the conceptual distinctions people use in their explanations are more complex and sophisticated than the person-situation dichotomy suggests. The authors, therefore, introduce a model of the conceptual structure of folk behavior explanations (the network of concepts and assumptions on which explanations are based) and test it in 4 studies. The modes and features of behavior explanations within this conceptual structure also have specific social functions. In 2 additional studies, the authors demonstrate that people alter distinct features of their explanations when pursuing particular impression-management goals and that listeners make inferences about explainers' goals on the basis of these features.

Percutaneous stenting of right pulmonary artery stenosis in fibrosing mediastinitis.

Pulmonary artery stenosis is an uncommon complication of fibrosing mediastinitis. Previous medical and surgical therapies have provided limited clinical efficacy without objective evidence of clinical improvement. With the advantages of limited invasiveness and absent need for prolonged drug therapy, percutaneous stent deployment to relieve pulmonary artery obstruction represents a novel treatment for this rare disorder.