No description available.

There is little information available about the relationship of newborn vitamin D status with pregnancy outcome and infant health. The purpose of this cross-sectional study was to estimate the prevalence of vitamin D deficiency and insufficiency in newborns in the Saskatoon Health Region, identify risk factors for low neonatal levels of vitamin D, and determine whether any association exists between low levels of vitamin D and adverse pregnancy and neonatal outcomes. The Newborn Vitamin D Study was conducted between December, 2011 and February, 2012. Sixty-five maternal-fetal dyads delivering in the Saskatoon Health Region were included in the study. Mean cord blood vitamin D level was 64.1 nmol/L (standard deviation = 19.8 nmol/L), which is in the insufficient range. Cord blood vitamin D level was deficient (<50 nmol/L) in 22% and insufficient (50-75 nmol/L) in 48% of the 65 newborns studied. Simple linear regression indicated that low weight gain during pregnancy is significantly associated with low vitamin D levels (p = 0.04). However, younger maternal age (p < 0.01) and urban area of residence (p = 0.09) were the strongest predictors of low cord blood vitamin D levels in a multiple linear regression model (R2 of 0.519, p = 0.003). Cord blood vitamin D levels were not significantly associated with any pregnancy or neonatal outcomes. Despite 85% of mothers reporting having taken a daily prenatal supplement, 70% of newborns in our study population had either an insufficient or deficient cord blood vitamin D status. This suggests that prenatal supplements, which typically contain 400 IU of vitamin D, contain an inadequate dose of vitamin D to produce sufficient cord blood vitamin D levels in most newborns. Further research is necessary to inform maternal vitamin D supplementation guidelines and to investigate the role of vitamin D in pregnancy outcomes and infant health.

Successful engraftment is highly dependent on the quality and quantity of stem cells and nucleated cells in cord blood. Storage of umbilical cord blood is expensive and it will be very useful if factors that influence cell count and viability could be identified to aid in the decision to process and store cord blood collections for the ultimate aim of successful engraftment. This study determined the standards for laboratory parameters of haematopoietic potential, such as collection volume, post processing volume, CD34+/45+ cell counts and viability of stem cells and leukocytes and cell ratios for the cord blood bank. In this research we determined whether maternal age and infant gender have an effect on laboratory parameters. We studied the effect of 4°C and room temperature (RT) as well as the period of storage on the same laboratory parameters. The quality and recovery of stem cells and leukocytes after laboratory manipulation was determined. Established standards for leukocyte count, stem cell count and collection volume compare well with other international UCB banks. Maternal age and infant gender have no influence on laboratory parameters and could therefore not be used as a measure of cell quantity and quality prior to processing. Cell count and cell viability of stem cells is not significantly influenced by 4°C or RT temperature or 24h and 48h storage. Leukocyte cell count and viability is not affected by storage temperature, but increased storage periods showed high levels of leukocyte cell count deterioration and decreased leukocyte cell viability. Processing of UCB causes significant cell loss in stem cells and leukocytes. Processing or no processing of UCB has showed no affect on the viability of stem cells stored at different storage periods and temperature. Temperature has no affect on leukocyte cell counts and viability of either processed or unprocessed leukocytes but increased storage periods dramatically decrease leukocyte count and viability. The information generated by this study will assist in the process of optimizing the storage of UCB. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Immunology / unrestricted

Cord blood storage, use, and donation is a rising trend. The cells found in the blood of the umbilical cord can be used to treat various life threatening diseases. It has been shown that the use of these cells can produce results that are just as effective as a bone marrow transfusion. The yield of cells from a sample of cord blood is not always enough to be effective for a transfusion in adults. As such children are the primary demographic for cord blood transfusions. For this reason, prospective parents are taking notice of the trend. Currently, federal and state statutes are set up to promote the introduction of cord blood use. What current law fails to recognize is that cord blood is in use and has a lot of potential. For this reason laws need to be updated to better reflect the current market. A more proactive approach needs to be taken to better utilize the potential of cord blood. As the trend is popularized there is an increasing notion that informed consent is not uniform enough, state laws do not adequately promote cord blood use, and there is a discrepancy between the standards of public and private cord blood banks. In order to improve upon these issues it is necessary to review the laws that are currently in place and then expand upon them so that they better reflect the storage, use, and donation of the blood. If umbilical cord blood becomes more than medical waste, as is projected to happen, then there is a need for an adequate legal foundation that protects the interests of all parties involved, especially prospective parents.

Thesis (Master, Microbiology & Immunology) -- Queen's University, 2013-09-30 22:46:35.072

Dose limiting haematotoxicity has been associated with a range of therapeutic agents used for the treatment of a number of different conditions. Haematotoxicity is usually assessed as part of the preclinical safety studies in experimental animals, where changes in peripheral blood cell numbers and bone marrow cellularity are determined at the end of the study. Often no information on the mechanism of the haematotoxicity is revealed. This thesis demonstrates how in vitro bone marrow cultures can be utilized to assist in the assessment of haematotoxicity by two different approaches; firstly, in vitro bone marrow cultures can be used to assess the haematopoietic lineage specificity of vincristine sulphate, vinblastine sulphate, hydroxyurea and anagrelide hydrochloride using clonogenic cultures, enabling ranking of these compounds according to their haematotoxicity. Secondly, using in vitro assays only, elucidate the mechanism(s) of the megakaryocytic lineage specific inhibition of anagrelide hydrochloride. To this end both clonogenic cultures and LTBMC offer the ability to elucidate mechanisms of action on multipotent stem cells, lineage specific cells and effects on the bone marrow microenvironment following single and repeated administration. In addition, the combination of cell identification techniques flow cytometry and light microscopy was shown to provide a more detailed understanding of the different cell populations within the non-adherent cell layer. In vivo AN reduces platelet counts only, however, the mechanism of the megakaryocyte specific toxicity by AN is not understood. In these studies, the mechanism (s) of the megakaryocytic lineage haematotoxicity of AN was examined using the established human clonogenic and LTBMC. The action of AN was shown to be focused at a late stage in megakaryocyte (Mk) colony development. Ranking the potential mechanisms of action of AN by concentration at which they were noted, the inability to organize the microtubules appears to be secondary to 1) alteration in cell cycling, 2) surface receptor expression and 3) inhibition in achieving high (greater than 8N) ploidy number. However, identification of the primary mechanism based solely on concentration seems to be very crude and most probably reflects a limitation of in vitro systems. The inhibition of platelet production by AN is most likely a result from a combination of mechanisms; inhibition of cell cycling, disruption in the expression of cell surface receptors, inhibition of the ability of the cells to increase ploidy number and an associated inability to organize microtubules leading to a reduction in platelet release. This work also demonstrated the importance of the selection of the source of bone marrow used in the cultures. The concentration at which 50 percent of Mk colony growth was inhibited (IC50) by AN for murine cells was markedly (46 fold) different (88.6μM) compared to the IC50 with human cord blood (hCB) (1.92μM). This disparity is indicative of differences in species sensitivity possibly related to AN having a greater affinity towards the human c-mpl chrombopoietin (TPO) receptor than the equivalent murine receptor as suggested by McCarty et al (2006). This work highlights the utility of in vitro bone marrow cultures as a tool for investigating the lineage specific haematotoxicity by evaluating compounds used in the treatment of ET. In addition in vitro haematopoietic cultures can successfully be used as a tool to investigate potential mechanism(s) of haematotoxicity as demonstrated herein by providing an insight to mechanism of platelet count reduction by AN.

No description available.

No description available.

The blood system is organized as a developmental hierarchy in which rare hematopoietic stem cells (HSCs) generate large numbers of immature progenitors and differentiated mature blood cells. In this process, at least ten distict lineages are specified from multipotent stem cells, however the cellular and molecular organization of the hematopoietic hierarchy is a topic of intense investigation. While much has been learned from mouse models, there is also an appreciation for species-specific differences and the need for human studies. Blood lineages have been traditionally grouped into myeloid and lymphoid branches, and the long-standing dogma has been that the separation between these branches is the earliest event in fate specification. However, recent murine studies indicate that the progeny of initial specification retain the more ancestral myeloid potential. By contrast, much less is known about the progenitor hierarchy in human hematopoiesis. To dissect human hematopoiesis, we developed a novel sorting scheme to isolate human stem and progenitor cells from neonatal cord blood and adult bone marrow. As few as one in five single sorted HSCs efficiently repopulated immunodeficient mice enabling interrogation of homogeneous human stem cells. By analyzing the developmental potential of sorted progenitors at a single-cell level we showed that earliest human lymphoid progenitors (termed LMPs) possess myelo-monocytic potential. In addition to B-, T-, and natural killer cells, LMPs gave rise to dendritic cells and macrophages indicating that these closely related myeloid lineages also remain entangled in lymphoid development. These studies provide systematic insight into the organization of the human hematopoietic hierarchy, which provides the basis for detailed genetic analysis of molecular regulation in defined cell populations. In a pilot study, we investigated the role of a zinc finger transcription factor (ZNF145), PLZF, in myeloid development. We found that PLZF restrained proliferation and differentiation of myeloid progenitors and maintained the progenitor pool. Induction of ERK1/2 by myeloid cytokines, reflective of a stress response, leads to nuclear export and inactivation of PLZF, which augments mature cell production. Thus, negative regulators of differentiation can serve to maintain developmental systems in a primed state, so that their inactivation by extrinsic signals can induce proliferation and differentiation to rapidly satisfy increased demand for mature cells. Taken together, these studies advance our understanding of the cellular and molecular architecture of human hematopoiesis.

Platelet- and plasma-derived factor Va are absolutely essential for thrombin generation catalyzed by the prothrombinase complex, a 1:1 stoichiometric complex of the serine protease factor Xa and the nonenzymatic cofactor, factor Va, assembled on an appropriate membrane surface in the presence of calcium ions. Two whole blood pools of the procofactor, factor V, exist: approximately 75% circulates in the plasma as a single chain inactive molecule, while the other 25% resides in platelet α-granules in a partially proteolytically-activated state. Our laboratory demonstrated that the platelet-derived cofactor originates following endocytosis of plasma-derived factor V by megakaryocytes, the platelet precursor cells, via a two receptor system including an uncharacterized, specific factor V receptor and low density lipoprotein receptor related protein-1. Following endocytosis factor V is physically and functionally modified and trafficked to the platelet α-granule from where it is released upon platelet activation at sites of vascular injury. The first goal of this dissertation was to define how factor V endocytosis changes over the course of megakaryocyte development. Hematopoietic multipotential stem cells were isolated from human umbilical cord blood and subjected to ex vivo differentiation into megakaryocytes. Megakaryocyte differentiation was assessed by flow cytometry using fluorescently-labeled antibodies against megakaryocyte- and platelet-specific markers and factor V directly conjugated to a fluorophore over 12 days. Differentiation was confirmed by a decrease in a stem cell marker (CD34) and an increase in a mature megakaryocyte marker (CD42) and coincident with factor V endocytosis. Live cell imaging verified differentiation and permitted the observation of proplatelet formation, the precursor to circulating platelets. Analogous experiments verified the trafficking of factor V into proplatelet extensions. Factor V is a highly glycosylated protein: potential roles of these glycans may be endocytosis and trafficking by megakaryocytes. We previously demonstrated that factor V endocytosis is mediated by the light chain region of the procofactor. This region of factor V contains three glycans - one high mannose and two complex N-linked glycans. In the second part of this dissertation, a role for the complex N-linked glycans at Asn1675 and Asn2181 of the factor V light chain in factor V endocytosis by megakaryocytes was assessed. Exoglycosidases were used to selectively trim the complex N-linked glycans on human factor V under native conditions. Treatment with neuraminidase removed 100% of the sialic acid residues on the factor V light chain as demonstrated by gel electrophoresis and mass spectrometry. Treatment with β-1,4-galactosidase removed 69% of the galactose residues at Asn1675 and 100% at Asn2181. Glycosidase-treated factor Va behaves similarly to untreated factor Va in thrombin generation assays suggesting that cofactor activity is unaltered by glycan trimming. In addition, glycan removal had no effect on factor V endocytosis by megakaryocyte-like cells. These observations suggest that complex N-linked glycans on the factor V light chain are not important for factor Va cofactor activity or factor V endocytosis by megakaryocyte-like cells, which strongly suggests that they have a role in trafficking.