Modulation of megakaryocytopoiesis by thrombopoietin: the c-Mpl ligand

We have further characterized the biological activities, mechanism of action, and target cell populations of recombinant human and murine thrombopoietin (rhTPO and rmTPO) in in vitro human and murine model systems. Alone, hTPO or mTPO stimulated the maturation of immature murine megakaryoblasts as measured in a single cell assay. The combination of hTPO or mTPO and interleukin-6 (IL-6) resulted in a further increase in megakaryocyte differentiation in this system. Murine TPO stimulated mouse megakaryocyte progenitor development. Human megakaryocyte progenitor development was potentiated by hTPO alone and further augmented in the presence of the early-acting cytokines (IL-3) or kit ligand/stem cell factor (KL/SCF). To further define the mechanism of action of TPO, neutralization studies were performed with antisera to IL-3, granulocyte-macrophage colony-stimulating factor (GM- CSF), IL-1 beta, and IL-11. No diminution in TPO activity was observed in the presence of these antisera. Moreover, because adhesive interactions are known to modulate hematopoiesis, we studied whether hTPO might alter such interactions between human bone marrow (BM) megakaryocytes and human BM stromal fibroblasts. No changes were observed in either megakaryocyte expression of the surface molecules lymphocyte function-associated antigen-1, very late activation antigen- 4, or intercellular adhesion molecule-1 or the adhesion of megakaryocytes to stromal fibroblasts after treatment with the growth factor. Furthermore, no induction of secretion of the cytokines IL-1 alpha, IL-1 beta, GM-CSF, IL-6, granulocyte-CSF, tumor necrosis factor- alpha, transforming growth factor-beta 1, or transforming growth factor- beta 2 by primary human BM megakaryocytes was noted after treatment of the cells with hTPO. To address whether TPO affects very primitive hematopoietic progenitors, we studied the residual cells from the BMs of mice treated with high doses of 5-fluorouracil. Although no effect of mTPO alone was noted on the viability or replication of such primitive murine progenitor populations, the triple combination of IL-3 + KL/SCF + TPO stimulated growth of megakaryocyte progenitors. These results indicate that TPO is a highly lineage-specific growth factor whose primary biological effects are likely to be direct modulation of the growth and maturation of committed megakaryocyte precursors and immature megakaryoblasts.     

Phase I trial of interleukin-2 after unmodified HLA-matched sibling bone marrow transplantation for children with acute leukemia

Allogeneic bone marrow transplantation (BMT) for advanced acute leukemia is associated with a high risk of relapse. It is postulated that interleukin-2 (IL-2) administered after BMT might induce or amplify a graft-versus-leukemia effect and thereby reduce the relapse rate. To identify an IL-2 regimen for testing this hypothesis, a phase I trial of IL-2 (Roche) was performed in children in complete remission (CR) without active graft-versus-host disease (GVHD) off immunosuppressive agents after unmodified allogeneic matched-sibling BMT for acute leukemia beyond first remission. Beginning a median of 68 days after BMT, 17 patients received escalating doses of induction IL-2 (0.9, 3.0, or 6.0 x 10(6) IU/m2/d representing levels I, II, and III) for 5 days by continuous intravenous infusion (CIV). After 6 days of rest, they received maintenance IL-2 (0.9 x 10(6) IU/m2/d) for 10 days by CIV infusion. Levels I and II were well-tolerated, but, of 6 patients at level III, 1 developed pulmonary infiltrates, 1 developed hypotension (both resolved), and 1 died of bacterial sepsis and acute respiratory distress syndrome. Grade II acute GVHD developed in 1 patient at level I and 1 at level III. The maximum tolerated dose of induction IL-2 was level II. IL-2 induced lymphocytosis, with an increase in CD56+ and CD8+ cells. Ten patients remain in CR at 5+ to 67+ months. Thus, a regimen of IL-2 has been identified that did not induce a high incidence of acute GVHD when administered to children after unmodified allogeneic BMT. Its clinical activity will be assessed in a phase II trial.     

Evolution of Ebola Virus Disease from Exotic Infection to Global Health Priority,Liberia, Mid-2014

Over the span of a few weeks during July and August 2014, events in West Africa changed perceptions of Ebola virus disease (EVD) from an exotic tropical disease to a priority for global health security. We describe observations during that time of a field team from the Centers for Disease Control and Prevention and personnel of the Liberian Ministry of Health and Social Welfare. We outline the early epidemiology of EVD within Liberia, including the practical limitations on surveillance and the effect on the country’s health care system, such as infections among health care workers. During this time, priorities included strengthening EVD surveillance; establishing safe settings for EVD patient care (and considering alternative isolation and care models when Ebola Treatment Units were overwhelmed); improving infection control practices; establishing an incident management system; and working with Liberian airport authorities to implement EVD screening of departing passengers.     

Alternative referent standards for cardiac normality. Implications for diagnostic testing

The radionuclide ventriculographic exercise response was evaluated in three patient populations representing alternative referent standards for cardiac normality: patients with normal coronary arteriograms, healthy volunteers, and uncatheterized patients with a low probability of coronary artery disease. Disease probability was determined by Bayesian analysis of age, sex, symptoms, and the results of cardiac fluoroscopy, exercise electrocardiography, or thallium scintigraphy. A wide range of ventriculographic responses was noted in the 62 catheterized normal patients; 21 (34%) had an abnormal ejection fraction response and 22 (35%) had an abnormal wall motion response. In contrast, the ejection fraction and wall motion responses were normal in the 9 volunteers. In 90 patients (18 catheterized and 72 uncatheterized) who had low disease probability (less than 1%), abnormal responses were rare; the ejection fraction response was abnormal in only 7% and the wall motion response was abnormal in 8%. Thus, these three populations are not equivalent referent standards of normality. Volunteers and patients with low disease probability provide too strict a standard, and their use can overestimate test specificity; catheterized normal patients, on the other hand, provide too lenient a standard, and their use can underestimate test specificity.     

Astrovirus and adenovirus associated with diarrhea in children in day care settings

The relative importance of astrovirus and adenoviruses as etiologic agents of diarrhea among children in day care was examined. Stool specimens from this prospective study were screened for both astrovirus and adenovirus hexon with two new indirect double-antibody assays and for enteric adenoviruses with an EIA specific for serotypes 40 and 41. Astrovirus was detected in a significantly greater percentage of children with diarrhea (4%, 21/524) than of those without (less than 1%, 1/138) (P less than .05); however, no difference between such such children with adenovirus infections was found (8%, 43/565, and 8%, 10/129, respectively). Overall, 30% (13/43) of all adenovirus hexon-positive specimens were enteric serotypes, and by extrapolation, enteric adenoviruses were identified in an equal percentage of children (2%) with and without diarrhea. This study documents the presence of astrovirus and enteric adenoviruses among children in day care in the United States, associates astrovirus with diarrhea in this setting, and suggests that viral agents may be the most common enteric pathogens among children with diarrhea in day care.     

Inefficacy of pneumococcal vaccine in a high-risk population

Use of pneumococcal vaccine remains controversial. To further study this question, 89 patients hospitalized at the Denver Veterans Administration Medical Center with pneumococcal bacteremia were chosen as the case group for a case-control study. The control group was made up of patients matched on the basis of age, date of admission, and comorbid conditions. Vaccination status in the bacteremic patients and control patients was determined, as were pneumococcal serotypes among the bacteremic patients. If the vaccine were protective, vaccination rates should be higher among the control patients, and serotype distribution should be different in vaccinated and nonvaccinated bacteremic patients. There were no differences between vaccination rates among bacteremic patients (29 percent) and control patients (24 percent). Furthermore, 65 percent of the blood isolates from nonvaccinated bacteremic patients were serotypes included in the vaccine, as compared with 69 percent of the isolates in vaccinated bacteremic patients. Pneumococcal vaccine did not appear to be protective in this high-risk population.     

Corticobasal and ataxia syndromes widen the spectrum of C9ORF72 hexanucleotide expansion disease

Recently, a hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72 was reported as the cause of chromosome 9p21‐linked frontotemporal dementia‐amyotrophic lateral sclerosis (FTD‐ALS). We here report the prevalence of the expansion in a hospital‐based cohort and associated clinical features indicating a wider clinical spectrum of C9ORF72 disease than previously described. We studied 280 patients previously screened for mutations in genes involved in early onset autosomal dominant inherited dementia disorders. A repeat‐primed polymerase chain reaction amplification assay was used to identify pathogenic GGGGCC expansions. As a potential modifier, confirmed cases were further investigated for abnormal CAG expansions in ATXN2. A pathogenic GGGGCC expansion was identified in a total of 14 probands. Three of these presented with atypical clinical features and were previously diagnosed with clinical olivopontocerebellar degeneration (OPCD), atypical Parkinsonian syndrome (APS) and a corticobasal syndrome (CBS). Further, the pathogenic expansion was identified in six FTD patients, four patients with FTD‐ALS and one ALS patient. All confirmed cases had normal ATXN2 repeat sizes. Our study widens the clinical spectrum of C9ORF72related disease and confirms the hexanucleotide expansion as a prevalent cause of FTD‐ALS disorders. There was no indication of a modifying effect of the ATXN2 gene.     

Anticardiolipin antibodies and risk of thromboembolic disease in young Jamaican women

BACKGROUND: Anticardiolipin antibodies (aCL) are a heterogeneous group of antiphospholipid antibodies that are associated with arterial and venous thrombosis. We measured aCL in women, aged 15-49 years, to determine if they are an independent risk factor for thromboembolic disease. STUDY DESIGN: Case--control study METHODS: Fifty cases were studied including venous thromboembolism (n=29), stroke and myocardial infarction (n=21), along with 148 age-matched controls. Serum samples were assayed for aCL and anti-beta2 glycoprotein 1 antibodies using the enzyme-linked immunosorbent assay (ELISA). Information on other risk factors was obtained by a standardized questionnaire. RESULTS: aCL were present in 16/50 (32%) of cases compared with 25/148 (17%) of controls (P[?]=[?]0.02). Unadjusted odds ratio (OR) and 95% confidence interval (95% CI) for thromboembolic disease associated with aCL was 2.32 (1.10--4.87). Other risk factors were hypertension, 2.93 (1.20--7.17) and a history of other heart diseases, 12.78 (1.32--123.60). Adjustment for hypertension, diabetes, oral contraceptive use, smoking, alcohol use, varicose veins, a family history of cardiovascular disease and a history of other heart diseases yielded OR (95%CI) 2.99 (1.32--6.80). beta2 glycoprotein 1-dependent aCL were also an independent risk factor, OR 4.56 (1.76--17.83). Subgroup analysis was carried out separately for cases of MI and stroke and for venous thrombosis. Adjusted OR (95% CI) associated with aCL in cases of MI and stroke was 1.76 (0.46--6.73) and 3.32 (1.15--9.54) for venous thromboembolism. CONCLUSION: aCL are a risk factor for thromboembolic disease in young Jamaican women. They confer a strong independent risk for venous thromboembolism.     

Angiographic changes in saphenous vein grafts are predictors of clinical outcomes

Background Previous studies have suggested that angiographic evidence of disease progression in coronary arteries increases the risk of subsequent coronary clinical events. This study ascertained whether patients enrolled in the Post Coronary Artery Bypass Graft Clinical Trial (POST CABG) who had substantial progression of atherosclerosis in ≥1 saphenous vein grafts (on the basis of assessment of baseline and follow-up angiograms obtained 4-5 years after study entry), but who had not reported clinical symptoms before follow-up angiography, were at a higher risk of subsequent events than patients who did not have substantial progression of atherosclerosis (decrease ≥0.6 mm in lumen diameter at site of greatest change from baseline). Methods All 1351 patients enrolled in the trial underwent baseline angiography; only the 961 patients who had follow-up angiography and no coronary events before the follow-up study were included in this analysis. The clinical center staff contacted patients to ascertain the events that had occurred after follow-up angiography (approximately 3.4 years later). Results Sixty-nine patients had died; 870 patients or relatives were interviewed, and 22 patients could not be contacted. Univariable estimates of relative risk associated with substantial progression ranged from 2.2 (P < .001) for cardiovascular death or nonfatal myocardial infarction to 3.3 (P < .001) for revascularization. Multivariable and univariable estimates of risk were similar. Conclusions The findings provide evidence that patients who had substantial progression of atherosclerosis in vein grafts are at an increased risk for subsequent coronary events and suggest that angiographic changes in vein grafts are appropriate surrogate measures for clinical outcomes. (Am Heart J 2003;145:262-9.)