118 research outputs found
MURINE HEMATOPOIETIC STEM-CELLS WITH LONG-TERM ENGRAFTMENT AND MARROW REPOPULATING ABILITY ARE MORE RESISTANT TO GAMMA-RADIATION THAN ARE SPLEEN COLONY-FORMING CELLS
MURINE HEMATOPOIETIC STEM-CELLS WITH LONG-TERM ENGRAFTMENT AND MARROW REPOPULATING ABILITY ARE MORE RESISTANT TO GAMMA-RADIATION THAN ARE SPLEEN COLONY-FORMING CELLS
MURINE HEMATOPOIETIC STEM-CELLS WITH LONG-TERM ENGRAFTMENT AND MARROW REPOPULATING ABILITY ARE MORE RESISTANT TO GAMMA-RADIATION THAN ARE SPLEEN COLONY-FORMING CELLS
Sensitivity of murine haemopoietic stem cell populations to X-rays and I MeV fission neutrons in vitro and in vivo under hypoxic I. Conditions
The radiosensitivity of primitive haemopoietic stem cells that repopulate the bone marrow with precursors of granulocytes and macrophages (MRA[CFU-C]), mature stem cells capable of forming spleen colonies in lethally irradiated recipients (CFU-S-7) and colony-forming units in culture (CFU-C) were determined in vitro and under hypoxic conditions in vivo for 1 MeV fission neutrons and 300 kV X-rays. The obtained D0's were compared with previously observed D0's after irradiation in vivo under normal oxic conditions. With 1 MeV fission neutron irradiation no significant difference in radiosensitivity of the cell populations was observed between normal in vivo irradiation and in vitro irradiation. With 300 kV X-rays a lower radiosensitivity for all three cell populations was observed after in vitro compared to in vivo irradiation. In vivo irradiation with fission neutrons under hypoxic conditions led to a small decrease in radiosensitivity. The obtained oxygen enhancement ratio (OER) for fission neutrons varied from 1.2 for MRA[CFU-C] to 1.5 for CFU-C. After in vivo irradiation with 300 kV X-rays under hypoxic conditions much higher OERs were observed. An OER= 1.8 was obtained for CFU-S and for MRA[CFU-C] and for CFU-C OER 3.0 and 2.9 were observed. These results indicate that the radioresistance of primitive haemopietic stem cells (MRA[CFU-C]) compared to mature stem cells (CFU-S-7) is mainly due to intrinsic factors and not to differences in localization or oxygenation between primitive and mature stem cells
GRK6 deficiency is associated with enhanced CXCR4-mediated neutrophil chemotaxis in vitro and impaired responsiveness to G-CSF in vivo
Regulation of haemopoietic stemâcell proliferation in mice carrying the Slj allele
We investigated a haemopoietic stromal defect, in mice heterozygous for the Slj allele, during haemopoietic stress induced by treatment with bacterial lipopolysaccharides (LPS) or lethal total body irradiation (TBI) and boneâmarrow cell (BMC) reconstitution. Both treatments resulted in a comparable haemopoietic stem cell (CFUâs) proliferation in Slj/+ and +/+ haemopoietic organs. There was no difference in committed haemopoietic progenitor cell (BFUâe and CFUâG/M) kinetics after TBI and +/+ boneâmarrow transplantation in Slj/+ and +/+ mice. the Slj/+ mice were deficient in their ability to support macroscopic spleen colony formation (65% of +/+ controls) as measured at 7 and 10 days after BMC transplantation. However, the Slj/+ spleen colonies contained the same number of BFUâE and CFUâG/M as colonies from +/+ spleens, while their CFUâs content was increased. On day 10 postâtransplantation, the macroscopic âmissingâ colonies could be detected at the microscopic level. These small colonies contained far fewer CFUâs than the macroscopic detectable colonies. Analysis of CFUâs proliferationâinducing activities in control and postâLPS sera revealed that Slj/+ mice are normal in their ability to produce and to respond to humoral stemâcell regulators. We postulate that Slj/+ mice have a normal number of splenic stromal ânichesâ for colony formation. However, 35% of these niches is defective in its proliferative support. Copyrigh
GRK6 deficiency is associated with enhanced CXCR4-mediated neutrophil chemotaxis in vitro and impaired responsiveness to G-CSF in vivo
Reservoirs and transmission routes of leprosy : a systematic review
Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae) and
the more recently discovered Mycobacterium lepromatosis (M. lepromatosis). The two leprosy
bacilli cause similar pathologic conditions. They primarily target the skin and the peripheral
nervous system. Currently it is considered a Neglected Tropical Disease, being
endemic in specific locations within countries of the Americas, Asia, and Africa, while in
Europe it is only rarely reported. The reason for a spatial inequality in the prevalence of leprosy
in so-called endemic pockets within a country is still largely unexplained. A systematic
review was conducted targeting leprosy transmission research data, using PubMed and
Scopus as sources. Publications between January 1, 1945 and July 1, 2019 were included.
The transmission pathways of M. leprae are not fully understood. Solid evidence exists of an
increased risk for individuals living in close contact with leprosy patients, most likely through
infectious aerosols, created by coughing and sneezing, but possibly also through direct contact.
However, this systematic review underscores that human-to-human transmission is
not the only way leprosy can be acquired. The transmission of this disease is probably much
more complicated than was thought before. In the Americas, the nine-banded armadillo
(Dasypus novemcinctus) has been established as another natural host and reservoir of M.
leprae. Anthroponotic and zoonotic transmission have both been proposed as modes of
contracting the disease, based on data showing identical M. leprae strains shared between
humans and armadillos. More recently, in red squirrels (Sciurus vulgaris) with leprosy-like lesions in the British Isles M. leprae and M. lepromatosis DNA was detected. This finding
was unexpected, because leprosy is considered a disease of humans (with the exception of
the armadillo), and because it was thought that leprosy (and M. leprae) had disappeared
from the United Kingdom. Furthermore, animals can be affected by other leprosy-like diseases,
caused by pathogens phylogenetically closely related to M. leprae. These mycobacteria
have been proposed to be grouped as a M. leprae-complex. We argue that insights
from the transmission and reservoirs of members of the M. leprae-complex might be relevant
for leprosy research. A better understanding of possible animal or environmental reservoirs
is needed, because transmission from such reservoirs may partly explain the steady global incidence of leprosy despite effective and widespread multidrug therapy. A reduction
in transmission cannot be expected to be accomplished by actions or interventions from the
human healthcare domain alone, as the mechanisms involved are complex. Therefore, to
increase our understanding of the intricate picture of leprosy transmission, we propose a
One Health transdisciplinary research approach.S1 PRISMA Checklist.S1 Text.https://journals.plos.org/plosntdsam2021Veterinary Tropical Disease
Complement Split Product C5a Mediates the LipopolysaccharideâInduced Mobilization of CfuâS and Haemopoietic Progenitor Cells, But Not the Mobilization Induced By Proteolytic Enzymes
Abstract. Intravenous (i.v.) injection of mice with lipopolysaccharide (LPS), and the proteolytic enzymes trypsin and proteinase, mobilizes pluripotent haemopoietic stem cells (CFUâs) as well as granulocyteâmacrophage progenitor cells (GMâCFU) and the early progenitors of the erythroid lineage (EâBFU) from the haemopoietic tissues into the peripheral blood. We investigated the involvement of the complement (C) system in this process. It appeared that the early mobilization induced by LPS and other activators of the alternative complement pathway, such as Listeria monocytogenes (Lm) and zymosan, but not that induced by the proteolytic enzymes, was absent in C5âdeficient mice. the mobilization by C activators in these mice could be restored by injection of C5âsufficient serum, suggesting a critical role for C5. The manner in which C5 was involved in the C activationâmediated stem cell mobilization was studied using a serum transfer system. C5âsufficient serum, activated in vitro by incubation with Lm and subsequently liberated from the bacteria, caused mobilization in both C5âsufficient and C5âdeficient mice. C5âdeficient serum was not able to do so. the resistance of the mobilizing principle to heat treatment (56°C, 30 min) strongly suggests that it is identical with the C5 split product C5a, or an in vivo derivative of C5a. This conclusion was reinforced by the observation that a single injection of purified rat C5a into C5âdeficient mice also induced mobilization of CFUâs. Copyrigh
HemaMaxâą, a Recombinant Human Interleukin-12, Is a Potent Mitigator of Acute Radiation Injury in Mice and Non-Human Primates
HemaMax, a recombinant human interleukin-12 (IL-12), is under development to address an unmet medical need for effective treatments against acute radiation syndrome due to radiological terrorism or accident when administered at least 24 hours after radiation exposure. This study investigated pharmacokinetics, pharmacodynamics, and efficacy of m-HemaMax (recombinant murine IL-12), and HemaMax to increase survival after total body irradiation (TBI) in mice and rhesus monkeys, respectively, with no supportive care. In mice, m-HemaMax at an optimal 20 ng/mouse dose significantly increased percent survival and survival time when administered 24 hours after TBI between 8â9 Gy (p<0.05 Pearson's chi-square test). This survival benefit was accompanied by increases in plasma interferon-Îł (IFN-Îł) and erythropoietin levels, recovery of femoral bone hematopoiesis characterized with the presence of IL-12 receptor ÎČ2 subunitâexpressing myeloid progenitors, megakaryocytes, and osteoblasts. Mitigation of jejunal radiation damage was also examined. At allometrically equivalent doses, HemaMax showed similar pharmacokinetics in rhesus monkeys compared to m-HemaMax in mice, but more robustly increased plasma IFN-Îł levels. HemaMax also increased plasma erythropoietin, IL-15, IL-18, and neopterin levels. At non-human primate doses pharmacologically equivalent to murine doses, HemaMax (100 ng/Kg and 250 ng/Kg) administered at 24 hours after TBI (6.7 Gy/LD50/30) significantly increased percent survival of HemaMax groups compared to vehicle (p<0.05 Pearson's chi-square test). This survival benefit was accompanied by a significantly higher leukocyte (neutrophils and lymphocytes), thrombocyte, and reticulocyte counts during nadir (days 12â14) and significantly less weight loss at day 12 compared to vehicle. These findings indicate successful interspecies dose conversion and provide proof of concept that HemaMax increases survival in irradiated rhesus monkeys by promoting hematopoiesis and recovery of immune functions and possibly gastrointestinal functions, likely through a network of interactions involving dendritic cells, osteoblasts, and soluble factors such as IL-12, IFN-Îł, and cytoprotectant erythropoietin
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