The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation

Haumea-one of the four known trans-Neptunian dwarf planets-is a very elongated and rapidly rotating body. In contrast to other dwarf planets, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system, and the Centaur Chiron was later found to possess something similar to Chariklo's rings. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multi-chord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea's equator and the orbit of its satellite Hi'iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea's spin period-that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea's largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected.

[Promoting the quality of health surveillance of workers exposed to wood dust, with particular care to NPSC, in the territory of the Health Agency of Florence]

Wood dust can cause occupational-related naso-sinusal cancer, characterized by a latency period of about 40 years. The Tuscany Cancer Registry estimates that cases of NPSC are from 20-25 per year into the Region (33% related to wood dust). These neoplasms are surgically treatable at early-stage and, for this reason, a rapid endoscopic diagnosis is considered to be reasonably useful for prognostic issues. We used a questionnaire to investigate nasal symptoms and NOSQ and SOLAR questionnaires to highlight respiratory/skins diseases, and a spirometry for each worker. Subjects with a working-age of more than 15 years, and those that were positive to the questionnaire and/or to the medical history were were referred to a specialist in otolaryngology. The prevalence of endoscopic positive findings--detected especially in subjects with a working age of more than 15 years--confirms the significance of the problem.

Erythropoietin upregulates the expression of its own receptor in TF-1 cell line

In the erythroleukemia cell line TF-1, recombinant human erythropoietin (rHEpo), but not c-kit ligand, enhanced the number of cells expressing the erythropoietin receptor (EpoR), as measured by flow-cytometric analysis of binding of the biotin-labeled Epo. Moreover, 125I-Epo binding and Scatchard analyses, indicated that TF-1 cells, maintained in standard conditions with IL-3, and those stimulated with c-kit ligand, bear a single class of EpoR. On the other hand, cells cultured in the presence of rHEpo had a higher number of receptors than IL-3 or c-kit ligand-stimulated cells, and had two binding sites with different affinities for the ligand. EpoR mRNA expression was higher in cells exposed to rHEpo than in IL-3 or c-kit-stimulated cells. This difference may have been dependent on either a higher level of transcription or an increased stability of mRNA. The observed changes of EpoR in rHEpo-stimulated TF-1 cell line could cooperate, together with the alteration of the gene (3' end deletion), in the occurrence of the erythroleukemic process. Changes induced in EpoR by rHEpo were not accompanied by an increase in the expression of glycophorin A or globin chain mRNAs. This may suggest that rHEpo is unable to induce erythroid differentiation in TF-1 cells. The results also indicate that this cell line could be a model for the investigation of the role of transcription factor(s) in the expression of EpoR, and for the study of the mechanism(s) underlying the changes in the number and affinity of the cell receptors.

Circulating CFU-E during hematopoietic recovery after allogeneic bone marrow transplantation: relationship to erythroid engraftment

The more mature erythroid progenitor assayable in vitro, the colony-forming unit-erythroid (CFU-E), is normally found in the bone marrow (BM) but is virtually absent from peripheral blood (PB), unlike the more immature progenitor, the burst-forming unit-erythroid (BFU-E). We report on the detection of CFU-E in the PB of six of 18 patients during hematopoietic recovery following allogeneic bone marrow transplantation (BMT); three of six patients with PB CFU-E were under treatment with recombinant human erythropoietin (rhEpo) as well as six of 12 who did not present with PB CFU-E. PB CFU-E were found as early as day 14 following BMT, reached a peak on day 28, and were still detectable on day 60. The presence of PB CFU-E was associated with signs of stimulated erythroid engraftment--an accelerated reticulocyte recovery, an increased number of reticulocytes, higher levels of serum transferrin receptor, and a reduction in transfusional requirements were found in these patients compared to those without PB CFU-E. The numbers of PB and BM BFU-E were similar in the two groups, as well as the numbers of PB and BM CFU-granulocyte/macrophage (CFU-GM) and multipotential CFU (CFU-GEMM); on the other hand, the percentage of BM BFU-E in S phase of the cell cycle was higher in the group of patients with PB CFU-E. While there was no difference between the two groups in serum Epo levels assayed on days 14 and 28 after BMT, patients with PB CFU-E had higher Epo levels in serum samples collected before starting the BMT procedure. These data suggest that the appearance of circulating CFU-E early after BMT is characteristic of a group of patients with an accelerated erythroid engraftment, although the mechanisms leading to the circulation of CFU-E after BMT remain unclear.

In vivo administration of stem cell factor enhances both proliferation and maturation of murine megakaryocytes

BACKGROUND

Stem cell factor (SCF) has already been shown to participate in the regulation of erythro- and granulopoiesis. The aim of this study was to define the possible role of SCF in the regulation of megakaryocytopoiesis.

METHODS

Stem cell factor activity has been assessed in an in vivo murine model, in which different doses of the factor were either given alone or in association with recombinant human erythropoietin (rhEpo). Mice were sacrificed after a six-day treatment to evaluate the effect of SCF on the number of bone marrow and spleen colony-forming units-megakaryocyte (CFU-Mk), and after a two-day treatment for evaluation of thrombopoietin-like activity.

RESULTS

We found that SCF induces a dose-related increase in the number of CFU-Mk in both the bone marrow and spleen of the treated mice, and that in the range of the doses used (from 25 to 200 mg/kg/day) the greatest activity was observed when a dose of 200 mg/kg/day was injected. The effect was enhanced by adding rhEpo to optimal SCF concentrations. SCF also stimulated megakaryocyte maturation as assessed by the megakaryocyte number, the size of acetylcholinesterase-positive cells, 35Sulphur (35S) incorporation into the newly formed platelets. All these parameters were only minimally affected by the addition of rhEpo.

CONCLUSIONS

These data suggest that SCF participates in the regulation of megakaryocytopoiesis and that its administration might have a role in the treatment of disorders of platelet production.

The use of erythropoietin in the treatment of post-bone marrow transplantation anemia

The issue of the role of erythropoietin (Epo) in the erythroid reconstitution after bone marrow transplantation (BMT) has been addressed in several recent studies. A defective Epo production in response to anemia has been shown to occur in patients undergoing allogeneic BMT unlike in most of those subjected to an autologous rescue. The factors involved in the inadequate Epo production in BMT are discussed, with particular attention to the role of the immunosuppressive drug cyclosporin-A, which has been shown to inhibit Epo production in both in vivo and in vitro models. The observation of defective Epo production eventually led to the development of clinical trials of recombinant human Epo (rhEpo) administration in BMT patients; the aims of these studies were to stimulate erythroid engraftment, hence reducing blood transfusion exposure. Although the number of patients studied up to now is relatively small, a benefit from rhEpo administration in terms of accelerated erythroid engraftment seems very likely, and it may also be associated with decreased transfusional needs in most treated patients. However, further studies are needed to better define indications, dosages and schedules of rhEpo in BMT patients.

The Use of Erythropoietin in the Treatment of Post-bone Marrow Transplatation Anemia

The issue of the role of erythropoietin (Epo) in the erythroid reconstitution after bone marrow transplantation (BMT) has been addressed in several recent studies. A defective Epo production in response to anemia has been shown to occur in patients undergoing allogeneic BMT unlike in most of those subjected to an autologous rescue. The factors involved in the inadeguate Epo production in BMT are discussed, with particular attention to the role of the immunosuppressive drug cyclosporin-A, which has been shown to inhibit Epo production in both in vivo and in vitro models. The observation of defective Epo production eventually led to the development of clinical trials of recombinant human Epo (rhEpo) administration in BMT patients; the aims of these studies were to stimulate erythroid engraftment, hence reducing blood transfusion exposure. Although the number of patients studied up to now is relatively small, a benefit from rhEpo administration in terms of accelerated erythroid engraftment seems very likely, and it may also be associated with decreased transfusional needs in most treated patients. However, further studies are needed to better define indications, dosages and schedules of rhEpo in BMT patients.

Constitutive expression of a megakaryocytic functional property by murine erythroleukemia (Friend) cells: the incorporation of serotonin

Murine Friend-derived erythroleukemia cells (MEL) are generally believed to be unipotential progenitors inducible to terminal erythroid differentiation. However, we found that MEL can constitutively incorporate significant amounts of radiolabeled serotonin ([3H]5-HT). Because this process is typical of cells belonging to the megakaryocytic lineage, we investigated the significance and mechanisms of 5-HT incorporation in the MEL system. We observed that: 1) normal murine erythroid cells and erythroid progenitors do not incorporate [3H]5-HT, as well as normal murine myeloid cells and the human myeloid cell line HL-60; on the other hand, the human erythroleukemia cell lines K562 and HEL, which have been shown to constitutively express megakaryocytic features, were able to incorporate [3H]5-HT; 2) MEL incorporated 5-HT by an active and saturable mechanism, dependent on temperature and sodium concentration in the medium; and 3) 5-HT uptake was very rapid. Moreover, because about 65% of cell-associated radioactivity was no longer displaced by the cold substrate, we assumed it to represent "true" cytoplasmic internalization. Finally, 5-HT incorporation by MEL was inhibited by clomipramine, ouabain, and reserpine, which are known inhibitors of 5-HT uptake in platelets. The commitment of MEL to terminal erythroid differentiation by hexamethylene bisacetamide or dimethyl sulfoxide greatly reduced the capacity to incorporate [3H]5-HT. These results seem to suggest that the MEL system, although mainly erythroid as regards its differentiation capability, constitutively expresses features of the megakaryocytic lineage, possibly disclosed by the ability to incorporate 5-HT. This hypothesis was further supported by the findings that 30%-40% of uninduced MEL were labeled by a polyclonal antibody raised against murine platelets that selectively recognized megakaryocytes in murine bone marrow smears.

Effects of miocamycin and erythromycin on polymorphonuclear cell function

Previous studies have shown that erythromycin can enter phagocytic cells, stimulating their functional activity. In this work we compared the effects of erythromycin and another newer macrolide antibiotic, miocamycin, on a series of in vitro tests aimed at evaluating their influence on polymorphonuclear cell (PMN) functions. Results indicate that erythromycin induces an increase in leukotriene B4 production in PMNs, while chemotaxis, killing of Candida albicans and respiratory burst are not influenced, at least at the doses used in this study. On the contrary, all these activities are significantly enhanced following incubation with miocamycin, and the response varies according to the antibiotic concentration.

Recombinant human erythropoietin for treatment of myelodysplastic syndromes

Nine patients with myelodysplastic syndromes and one patient with agnogenic myeloid metaplasia have been treated with recombinant human erythropoietin (rhEpo), at the dose of 150 U/kg/day. Although serum Epo levels were correlated with hemoglobin concentrations in the whole population of patients, they clearly appeared inadequate in some instances, if compared to those of a group of control subjects with iron deficiency anemia. Moreover, no correlation was found between serum Epo and reticulocytes. Six patients showed a partial or complete response to the treatment and the outcome was not correlated with the pre-therapy serum Epo levels; however, serum Epo was less than 100 mU/ml in three of four patients who achieved a complete response. The mechanism(s) by which Epo stimulated erythrocyte production in myelodysplastic patients is unclear, because the number of both the reticulocytes and erythroid progenitors remained unchanged during and at the conclusion of a three months' therapy. Further studies are needed to better define the optimal dosage required to correct anemia in myelodysplastic syndromes, and to clarify rhEpo mechanism of action in these diseases.