Glycoprotein Ib and glycoprotein IX are fully complexed in the intact platelet membrane

Two new murine monoclonal antibodies, AK 1 and SZ 1, reactive with the human platelet glycoprotein (GP) Ib-IX complex have been produced by the hybridoma technique. Both AK 1 and SZ 1 immunoprecipitated the GP Ib-IX complex from Triton X-100-solubilized, periodate-labeled platelets. With trypsinized, labeled platelets, AK 1, SZ 1, and FMC 25 (epitope on GP IX) immunoprecipitated a membrane-bound proteolytic fragment of the GP Ib-IX complex consisting of GP IX and an congruent to 25,000 mol wt remnant of the alpha-chain of GP lb disulfide-linked to the beta-subunit. Unexpectedly, although AK 1 and SZ 1 immunoprecipitated purified GP Ib-IX complex, neither antibody immunoprecipitated the individual components of this complex, GP Ib or GP IX. When GP Ib and GP IX were recombined, however, AK 1 and SZ 1 again immunoprecipitated the reformed complex, strongly suggesting that both antibodies were recognizing an epitope present only on the intact complex. Cross-blocking studies indicated that AK 1 and SZ 1 recognized a very similar or identical epitope that was proximal to the epitope for FMC 25. Both AK 1 and SZ 1 bound to a similar number of binding sites (congruent to 25,000) on intact platelets as monoclonal antibodies directed against either GP lb or GP IX. The combined data suggests that GP lb and GP IX are fully complexed in the intact platelet membrane.     

Myeloproliferative syndrome induced by MPSV in DBA/2 mice: presence of a mixed-colonies promoting activity (MPA) in the spleen

The myeloproliferative syndrome induced by the myeloproliferative sarcoma virus (MPSV) in DBA/2 mice stimulates the proliferation of pluripotent hemopoietic stem cells (HSC) and of progenitors committed toward granulomacrophagic and erythroid cell lines. This stimulation may result from a direct effect of the MPSV on HSC or from an indirect effect via locally secreted factors. Normal isogenic bone marrow cells were incubated in the mixed colony-forming unit system in semisolid medium supplemented with conditioned media obtained after incubating neoplastic spleen cells for 3 days at 37 degrees C. These spleen conditioned media contain an activity that is physically separable from MPSV by ultracentrifugation and which, in the presence of a very low quantity of erythropoietin, can induce in vitro the proliferation and differentiation of pluripotent HSC, detected by this Mix-CFU technique. We termed this activity mixed-colonies promoting activity (MPA). These results suggest that the hyperplasia of the nonlymphoid hematopoietic system in the neoplastic spleen results from an indirect effect of the MPSV on pluripotent HSC via locally secreted factors.     

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.     

Practice-Based Research Priorities for Palliative Care: Results From a Research-to-Practice Consensus Workshop

We employed the research-to-practice consensus workshop (RTP; workshops held in New York City and Tompkins County, New York, in 2013) model to merge researcher and practitioner views of translational research priorities in palliative care. In the RTP approach, a diverse group of frontline providers generates a research agenda for palliative care in collaboration with researchers. We have presented the major workshop recommendations and contrasted the practice-based research priorities with those of previous consensus efforts. We uncovered notable differences and found that the RTP model can produce unique insights into research priorities. Integrating practitioner-identified needs into research priorities for palliative care can contribute to addressing palliative care more effectively as a public health issue.Over the past 2 decades, palliative care has become established as a promising approach for addressing the needs of individuals with life-threatening illnesses from a holistic, interdisciplinary perspective. For this project, we defined palliative care as an approach that improves the quality of life of patients and families facing the problems encountered in life-threatening illness by preventing and relieving suffering. Core components of palliative care include providing relief from pain and other distressing symptoms, affirming dying as a normal process, integrating psychological and spiritual aspects of care, enhancing the quality of life of patients, and offering support systems to patients and their families to help them live as fully as possible until death occurs.Research suggests that palliative care results in positive patient outcomes, greater patient and family satisfaction, and significant cost savings.1,2 The American Public Health Association, the World Health Organization, and the Institute of Medicine3–6 have identified the development of a robust palliative care delivery system as a key public health issue because of the documented ability of palliative care to deliver effective and efficient patient- and symptom-focused care to a growing population in need.In its 2013 report the American Public Health Association specifically detailed the public health implications of palliative care, acknowledged the growing burden of advanced chronic illness and disease in older adults, and recommended key steps to address the problem. This policy statement called for federal, state, and local efforts to promote effective symptom management in populations with serious illness or at the end of life. Other recommended initiatives included the development of a palliative care workforce, educational programs to improve uptake and use of palliative and hospice care, and research funding to support the expansion of palliative care initiatives. Achieving these goals will require moving beyond traditional medical practices to include both policies and initiatives at the public health level.Despite the potential of palliative care to address the mental and physical health needs of individuals with advanced illness, significant knowledge gaps impede its reach and effectiveness. Reports from scientific bodies and consensus workshops have highlighted weaknesses in the literature and called for more research on palliative care and improved research methods.7–10 Thus, although both interest in and demand for palliative care are increasing, reviews of the knowledge base continue to lament the lack of research on many key issues.11,12Especially urgent is a research agenda that fits most closely with the needs of providers who deliver palliative care. The systematic engagement of community practitioners in a consensus process can lead to particularly useful and actionable recommendations for research,13–15 which are greatly needed at this stage in the development of the field. Therefore, to shed new light on research priorities in palliative care, we used a structured, participatory method designed to solicit practitioner input on research priorities: the research-to-practice consensus workshop (RTP) model.16We employed the RTP approach to identify knowledge gaps and types of studies that should be conducted to improve providers’ ability to deliver palliative care most effectively. This model harnesses practice wisdom by engaging clinicians, agency staff, and other practitioners with researchers in a process of articulating and refining research questions and research priorities that honors scientific expertise and practice wisdom.     

Plasma sRAGE is independently associated with increased mortality in ARDS: a meta-analysis of individual patient data

Purpose

The soluble receptor for advanced glycation end-products (sRAGE) is a marker of lung epithelial injury and alveolar fluid clearance (AFC), with promising values for assessing prognosis and lung injury severity in acute respiratory distress syndrome (ARDS). Because AFC is impaired in most patients with ARDS and is associated with higher mortality, we hypothesized that baseline plasma sRAGE would predict mortality, independently of two key mediators of ventilator-induced lung injury.

Methods

We conducted a meta-analysis of individual data from 746 patients enrolled in eight prospective randomized and observational studies in which plasma sRAGE was measured in ARDS articles published through March 2016. The primary outcome was 90-day mortality. Using multivariate and mediation analyses, we tested the association between baseline plasma sRAGE and mortality, independently of driving pressure and tidal volume.

Results

Higher baseline plasma sRAGE [odds ratio (OR) for each one-log increment, 1.18; 95% confidence interval (CI) 1.01–1.38; P?=?0.04], driving pressure (OR for each one-point increment, 1.04; 95% CI 1.02–1.07; P?=?0.002), and tidal volume (OR for each one-log increment, 1.98; 95% CI 1.07–3.64; P?=?0.03) were independently associated with higher 90-day mortality in multivariate analysis. Baseline plasma sRAGE mediated a small fraction of the effect of higher ΔP on mortality but not that of higher V_T.

Conclusions

Higher baseline plasma sRAGE was associated with higher 90-day mortality in patients with ARDS, independently of driving pressure and tidal volume, thus reinforcing the likely contribution of alveolar epithelial injury as an important prognostic factor in ARDS. Registration: PROSPERO (ID: CRD42018100241).

     

The adaptor protein Grb2b is an essential modulator for lympho-venous sprout formation in the zebrafish trunk

Vegfc/Vegfr3 signaling is critical for lymphangiogenesis, the sprouting of lymphatic vessels. In zebrafish, cells sprouting from the posterior cardinal vein can either form lymphatic precursor cells or contribute to intersegmental vein formation. Both, the Vegfc-dependent differential induction of Prox1a in sprouting cells as well as a Notch-mediated pre-pattern within intersegmental vessels have been associated with the regulation of secondary sprout behavior. However, how exactly a differential lymphatic versus venous sprout cell behavior is achieved is not fully understood. Here, we characterize a zebrafish mutant in the adaptor protein Grb2b, and demonstrate through genetic interaction studies that Grb2b acts within the Vegfr3 pathway. Mutant embryos exhibit phenotypes that are consistent with reduced Vegfr3 signaling outputs prior to the sprouting of endothelial cells from the vein. During secondary sprouting stages, loss of grb2b leads to defective cell behaviors resulting in a loss of parachordal lymphangioblasts, while only partially affecting the number of intersegmental veins. A second GRB2 zebrafish ortholog, grb2a, contributes to the development of lymphatic structures in the meninges and in the head, but not in the trunk. Our results illustrate an essential role of Grb2b in vivo for cell migration to the horizontal myoseptum and for the correct formation of the lymphatic vasculature, while being less critically required in intersegmental vein formation. Thus, there appear to be higher requirements for Grb2b and therefore Vegfr3 downstream signaling levels in lymphatic versus vein precursor-generating sprouts.