Short remission durations in therapy-related leukemia despite cytogenetic complete responses to high-dose cytarabine

Seventeen patients with therapy-related myelodysplastic syndrome (t- MDS) or therapy-related acute nonlymphocytic leukemia (t-ANLL) were treated with single-agent high-dose cytarabine (HDAC; 1 to 3 g/m2 every 12 hours for 12 doses). The initial neoplasm was still present in eight patients when t-MDS/t-ANLL developed. Fifteen of the 16 patients with chromosomal abnormalities in bone marrow cells had loss or rearrangement of chromosomes 5 and/or 7. One patient had a t(15;17), and one had inadequate material for cytogenetic analysis. Twelve patients had normal metaphase cells (3% to 71%). Indications for HDAC therapy were progressive pancytopenia in 13 patients or rising blast count in four. Five patients died of marrow hypoplasia following therapy. Four others had refractory t-ANLL and died within the subsequent 5 months. Only one of ten patients with a poor performance status (PS greater than or equal to 2 using the ECOG scale) achieved a complete remission, but all seven patients with a good performance status (PS less than or equal to 1) had a complete remission. Hematologic remissions were achieved in 8 patients (47%) after one (6 patients) or two (2 patients) induction courses and were confirmed by recovery of a 100% normal marrow karyotype in six of the seven patients who were retested. Patients in remission received one to four consolidation courses with HDAC alternating with cytarabine/doxorubicin, but seven relapsed within 8 months (median remission duration, 5 months). In every case, the original chromosomal abnormality reappeared at relapse. HDAC has a high response rate for good-performance patients with t-MDS/t-ANLL, but complete remissions are short even when confirmed cytogenetically and consolidated intensively.     

Busulfan-based regimens and allogeneic bone marrow transplantation in patients with myelodysplastic syndromes

Preparative regimens containing busulfan (BU) followed by allogeneic bone marrow transplantation (BMT) were used in 27 consecutive patients with myelodysplastic syndromes (MDS). The median age was 33 years (range, 4 to 54). Ten were female and 17 male. Sixteen patients had primary MDS, 11 other patients had antecedent hematologic diseases or developed MDS after cytotoxic and/or radiation therapy. Six patients had leukemic transformation and received antileukemic therapy before BMT. Pre-BMT cytogenetic studies showed complex chromosomal abnormalities in 13 patients, a simple abnormality in 5 patients, and normal chromosome in 8 patients. Three BU-based preparative regimens were used: 1 patient received BU 4 mg/kg orally (PO) daily for 4 days and cyclophosphamide (CY) 50 mg/kg intravenously (IV) daily for 4 days (BUCY-4); 24 patients received BU 4 mg/kg PO daily for 4 days, cytosine arabinoside (ara-C) 2 g/m2 IV every 12 hours for 4 doses, and CY 60 mg/kg IV daily for 2 days (BAC); and 2 patients with preceding Fanconi anemia received BU 2 mg/kg PO daily for 4 days followed by total lymphoid irradiation of 5 Gy. Seventeen of 27 patients are alive with no evidence of disease. Ten patients have died: 2 from hepatic veno- occlusive disease, 3 from sepsis, 1 from a cerebral bleed, 1 from a massive gastrointestinal (GI) bleed associated with acute graft-versus- host disease, 1 from hemolytic uremic syndrome with adult respiratory distress syndrome, 1 from bronchiolitis obliterans, and the only patient who did not engraft died from acute myeloid leukemia. Regimen- related toxicities (RRT) include GI tract (diarrhea, 14; stomatitis, 11), liver (9), cardiac (1), and skin (5). Patients who received a genotypically matched marrow graft had a significantly better disease- free survival (DFS) than patients who received a nongenotypic marrow graft (P = .02). The Kaplan-Meier analysis projects an overall DFS of 56% +/- 13% and 78% +/- 10% for patients who received a genotypically matched marrow graft. With the exception of a child who did not engraft, there was no relapse of MDS or leukemia. Excellent DFS, acceptable RRT, and the ease of administration are advantages of this regimen.     

Physiologic features of hemolysis axxociated with altered cation and 2,3-diphosphoglycerate content

A hemolytic disorder characterized by altered RBC cation composition (increases Na, decreases K), reduced monovalent cation content (decreased Na + K/liter RBC), and decreased levels of 2,3- diphosphoglycerate (2,3-DPG) is described. The etiology of these RBC abnormalities was not elucidated following extensive laboratory evaluation, although two important physiologic principles were manifested by this case: (1) Hemolysis was relatively well compensated (41% hematocrit) despite a significantly decreased RBC survival (51 Cr t 1/2 = 10.5 days). This effect presumably was due to reduced 2,3-DPG content (1.9 mumol/ml RBC) and the associated increase in whole blood oxygen affinity (P50 = 19.6 mm hg). (2) RBC size and water content were normal in spite of marked cation depletion. This anomaly was thought to reflect the osmotic effects of reduced polyvalent anion (2,3-DPG) content.     

Growth hormone-releasing hormone agonists ameliorate chronic kidney disease-induced heart failure with preserved ejection fraction

Therapies for heart failure with preserved ejection fraction (HFpEF) are lacking. Growth hormone-releasing hormone agonists (GHRH-As) have salutary effects in ischemic and nonischemic heart failure animal models. Accordingly, we hypothesized that GHRH-A treatment ameliorates chronic kidney disease (CKD)-induced HFpEF in a large-animal model. Female Yorkshire pigs (n = 16) underwent 5/6 nephrectomy via renal artery embolization and 12 wk later were randomized to receive daily subcutaneous injections of GHRH-A (MR-409; n = 8; 30 µg/kg) or placebo (n = 8) for 4 to 6 wk. Renal and cardiac structure and function were serially assessed postembolization. Animals with 5/6 nephrectomy exhibited CKD (elevated blood urea nitrogen [BUN] and creatinine) and faithfully recapitulated the hemodynamic features of HFpEF. HFpEF was demonstrated at 12 wk by maintenance of ejection fraction associated with increased left ventricular mass, relative wall thickness, end-diastolic pressure (EDP), end-diastolic pressure/end-diastolic volume (EDP/EDV) ratio, and tau, the time constant of isovolumic diastolic relaxation. After 4 to 6 wk of treatment, the GHRH-A group exhibited normalization of EDP (P = 0.03), reduced EDP/EDV ratio (P = 0.018), and a reduction in myocardial pro-brain natriuretic peptide protein abundance. GHRH-A increased cardiomyocyte [Ca²⁺] transient amplitude (P = 0.009). Improvement of the diastolic function was also evidenced by increased abundance of titin isoforms and their ratio (P = 0.0022). GHRH-A exerted a beneficial effect on diastolic function in a CKD large-animal model as demonstrated by improving hemodynamic, structural, and molecular characteristics of HFpEF. These findings have important therapeutic implications for the HFpEF syndrome.

The prognosis for heart failure with preserved ejection fraction (HFpEF), a complex clinical syndrome involving multiple comorbidities with limited treatment options (1–3), has not improved over decades, and numerous drug classes that are effective for heart failure with reduced ejection fraction (HFrEF) have, to date, shown limited to no clinical benefits in HFpEF (4–7). In addition, the relative scarcity of animal models (8–10) impedes discovery of novel therapies for HFpEF. One important cause of HFpEF is chronic kidney disease (CKD), which has among the worst outcomes of the HFpEF syndromes (11). It manifests predominantly with pathologic left ventricle (LV) remodeling characterized by LV hypertrophy with increased LV-mass index and relative wall thickness (RWT), impaired ventricular arterial coupling, right ventricular relaxation, and increased stroke work (SW) (11).Growth hormone-releasing hormone (GHRH) is a pleiotropic hormone that has extrapituitary effects, exerted via activation of GHRH receptors (12–15). In murine models of ischemic cardiomyopathy (ICM) with reduced ejection fraction (EF) (13), GHRH agonists (GHRH‐As) improve cardiac function and decrease scar size, mediated by myocardial GHRH receptor activation (14, 15). Importantly, GHRH actions in the heart are independent of the growth hormone–IGF1 axis (16). Further mechanisms of action include decreased apoptosis of cardiomyocytes and inflammatory responses (14, 17). The GHRH‐A, MR‐409, improved diastolic strain and reduced myocardial scar in a swine large-animal model with subacute ICM (12). Notably, in a murine HFpEF model using chronic administration of angiotensin II, GHRH-A prevented impairment of cardiomyocyte contractile function and relaxation and development of HFpEF features, including LV hypertrophy, collagen deposition, and diastolic dysfunction compared to placebo (18). Here, we developed a large-animal model of HFpEF using swine with CKD-induced HFpEF, a model that faithfully recapitulated the hemodynamic characteristics observed in humans, to test the hypothesis that GHRH-A ameliorates cardiac diastolic dysfunction.     

Exogenous tat protein activates human endothelial cells [see comments]

tat protein, a human immunodeficiency virus (HIV) gene product that functions as a transactivator for HIV replication, is known to be secreted extracellularly by infected cells. To determine the potential role of tat in the dissemination of HIV into extravascular tissue, this protein was examined for its ability to activate human endothelial cells. The results show that tat does indeed stimulate endothelial cells. This is evidenced by their expression of the endothelial- leukocyte adhesion molecules, E-selectin, critical for the initial binding of leukocytes to the blood vessel wall, and their increased synthesis of interleukin-6 (IL-6), a cytokine known to enhance endothelial cell permeability. Furthermore, tat acts synergistically with low concentrations of tumor necrosis factor-alpha to enhance IL-6 secretion. These data suggest that extracellular tat protein secreted or released into the microenvironment may contribute significantly to the determination of specific sites of leukocyte binding to blood vessels, to transmigration into tissue, and to eventual dissemination of HIV-infected cells or free virions into tissue.     

Association of red cell spherocytosis with deletion of the short arm of chromosome 8

Congenital spherocytic anemia is a common disorder, but in most cases the nature of the underlying membrane lesion is unknown and the genetic defect has not yet been unequivocally mapped to a chromosome. We studied two dysmorphic siblings with neurologic findings and hemolytic anemia. Clinical and laboratory findings in these two siblings were consistent with the diagnosis of congenital spherocytosis whereas both parents and two unaffected siblings were normal. The two affected children had an abnormal chromosomal complement as a result of a deletion of the short arm of chromosome 8 [(46,XX,del(8)(p11.1p21.1)]. These results suggest that a gene whose deletion results in a congenital spherocytic anemia phenotype resides on this region on the short arm of chromosome 8.     

Chromosome marker evidence for the bipotentiality of BFU-E

When mouse bone marrow cells are seeded in agar cultures containing erythropoietin or pokeweed mitogen stimulated spleen cell conditioned medium plus erythropoietin, megakaryocytes are found mixed with erythroid cells in approximately 40% of the erythropoietic bursts that develop in the cultures. Chromosome spreads of C-metaphases in such "megaerythro bursts" were prepared and stained in situ with a modification of the C-banding technique. In cultures seeded with mixtures of male and female cells, metaphases from individual megaerythro bursts were shown to be either all male of all female but not both. Moreover, tetraploid C-metaphases of megakaryocytes were found to be of the same sex as diploid C-metaphases of erythroid cells in the same megaerythro burst. These results provide evidence that in the mouse, a bipotential progenitor cell exists that has the capacity to give rise to cells of both the megakaryocytic and the erythrocytic lines of differentiation.     

Montreal platelet syndrome: a defect in calcium-activated neutral proteinase (calpain)

Platelets from patients with Montreal platelet syndrome (MPS) consistently display a defect in the mechanisms that regulate platelet size during shape change and undergo spontaneous aggregation and stir- induced microaggregate formation. We now provide data that the surface glycoprotein composition of MPS platelets is indistinguishable from that of normal platelets. However, a defect in calcium-activated neutral proteinase (calpain) was detected in MPS platelets. The specific activity of calpain in the cytosolic fraction of platelets from four MPS patients was found to be only 30% of that in platelets from normal control donors (n = 18, P less than .001). Additionally, platelets from MPS patients (n = 3) contained only 50% (P less than .001) of the calpain I catalytic subunit antigen found in platelets from normal control donors (n = 9). Platelets from the asymptomatic father/grandfather of the MPS patients had normal amounts of both total calpain proteolytic activity and calpain I catalytic subunit antigen. This represents the first report of a defect in calpain in human cells. The abnormally low calpain activity in MPS platelets may account for the platelet defects characteristic of this disorder.