Search

Objective: Murine embryonic stem cells can be differentiated into embryoid bodies (EBs), which serve as an in vitro model recapitulating many aspects of embryonic yolk sac hematopoiesis. Differentiation of embryonic stem cells deficient in either Gata-4 or Gata-6 results in EBs with disrupted visceral endoderm (VE). While lack of VE has detrimental effects on hematopoiesis in vivo, it is unclear whether lack of VE affects hematopoiesis in EBs. Therefore, we compared Gata-4 null (G4N) and Gata-6 null (G6N) EBs with wild-type EBs to assess their ability to commit to hematopoietic cells. Materials and Methods: EB VE formation was examined using cell-sorting techniques and analysis visceral endoderm gene expression. Hematopoietic progenitor potential of EBs cultured under various conditions was assessed using colony-forming assays. Results: Definitive erythroid, granulocyte-macrophage, and mixed colonies were significantly reduced in G4N and G6N EBs compared to wild-type EBs. Vascular endothelial growth factor (VEGF) expression and secretion were also reduced in both G4N and G6N EBs, consistent with VE serving as a site of VEGF production. Addition of exogenous VEGF165, to EB cultures completely rescued definitive colony-forming cells in G4N and G6N EBs. This rescue response could be blocked by addition of soluble Flk-1 Fc to EB cultures. Similarly, addition of exogenous Indian hedgehog to EB cultures also recovers the diminishment in definitive hematopoiesis in a reversible manner. Conclusion: These results suggest that the absence of VE in G4N and G6N EBs does not prevent emergence of definitive progenitors from EBs. However, the decreased level of VEGF and Indian hedgehog production in VE devoid G4N and G6N EBs attenuates definitive hematopoietic progenitor cell expansion. [Copyright &y& Elsevier]

Sea salt aerosol may be an important sink for reactive gaseous mercury (RGM) in the marine boundary layer, reducing ambient RGM concentrations and transferring the mercury (Hg) to the oceans and coastal ecosystems. The goal of this study was to determine the affinity of gaseous mercury for sea salt aerosol (SSA) by conducting adsorption experiments with sea salt-coated sampling denuders. In the first set of experiments, ambient outdoor air was passed through denuders coated with either KCl, as in the widely accepted method to sample RGM, or with NaCl, a primary component of sea salt aerosols. On the one sampling day in which RGM was above the MDL, the NaCl coated denuders removed Hg from the ambient air, equivalent to 87% of the RGM in the air (as determined by KCl denuders). For the second set of experiments HgCl generated in the laboratory was passed through denuders coated with KCl and either NaCl or sea salt. The NaCl denuders collected an average of 99 ± 16% of the mercury that the KCl denuders collected. Newly coated sea salt denuders collected 88 ± 17% of the amount of mercury that the KCl denuders collected, but interestingly the sea salt denuders capacity decreased with repeated use. These experiments demonstrate that HgCl, a major component of RGM has a strong affinity for NaCl and sea salt and is therefore likely to be scavenged by SSA. This study adds to the growing evidence that RGM is scavenged by sea salt aerosols and therefore more quickly deposited to the ocean and coastal environment. [ABSTRACT FROM AUTHOR]

Context Widening access to higher education is a political priority. Social trends among medical school applicants are presently monitored using information on parental occupation. However, not all students now provide this information on their university application forms. Objectives To compare the demographic characteristics of applicants who do and do not provide information about parental occupation, and to consider the utility of an alternative measure based on area of residence (Townsend score). Methods We surveyed the application forms of all individuals domiciled in England who made applications to English medical schools in 1996–2003. Results During 1996–2003, the proportion of applicants who did not declare parental occupation rose from 4.6% to 18.2%. Younger applicants were more likely to state that their parents were employed in professional/managerial occupations than mature applicants. White applicants were more likely to be from professional/managerial classes (72%) than were Black (60%) or Asian (60%) applicants. Although an association between socioeconomic class based on parental occupation and Townsend score was noted, this masked substantial variation between demographic groups. Applicants who did not disclose their parents' occupations were more likely to be non-White and to live in deprived areas. However, White applicants who did not state parental occupation were equally distributed by Townsend score. Conclusions The sole use of parental occupation or area-based measures to monitor widening participation programmes requires caution given the proportion of applicants who do not provide this information and the age and ethnic group differences noted. [ABSTRACT FROM AUTHOR]

Background Babesiosis is caused by Babesia microti and often transmitted via Ixodes scapularis. To the best of our knowledge, only 9 cases of vertical transmission have been reported. The spectrum of clinical presentation and optimal therapy for this population remains unknown. Methods Case 1 is a 4 week old female admitted with fever and irritability for 2 days. She was pancytopenic, with Hgb of 9.2 g/dL, Plt of 57 K/mm3, and absolute neutrophil count (ANC) of 500/mm3. Thin smear revealed 2.5% parasitemia. Mother was diagnosed with acute Lyme disease in the seventh month of pregnancy. Maternal serologies were positive for B. microti (IgM 1:100 and IgG >1:320). The infant received 1 PRBC transfusion and was treated with 10 days of atovoquone and azithromycin. Case 2 is a 5 week old female twin A admitted with 2 days of pallor, fatigue and poor feeding. Initial Hgb was 3.4 Gm/dL. Peripheral blood smear revealed many intraerythrocytic parasites consistent with B. microti. Thin smear obtained 24 hours after initiation of therapy showed 2% parasitemia. During hospitalization, the patient developed neutropenia with ANC nadir of 800/mm3. The patient required 4 PRBC transfusions and was treated with azithromycin and atovoquone for 10 days. The mother had an acute, self-limited febrile illness at 23 weeks gestation. At infant's presentation, maternal serologies revealed negative B. microti IgM and positive IgG (1:160). Placental tissue from both twins was positive for B. microti DNA by PCR. Twin B was asymptomatic, had negative B. microti blood PCR, a negative B. microti IgM, positive IgG of 1:30 felt to represent transplacental maternal antibody, and did not require treatment. Results Both infants were successfully treated without relapse. Conclusion Congenital babesiosis is rare and may cause profound hematologic disturbances. We report 2 cases exhibiting neutropenia in addition to anemia and thrombocytopenia, supporting recent assertions by Wormser et al. that this is a common finding. In addition, Case 2 presented with a severe hemolytic anemia significantly worse than previously reported. Finally, we demonstrated successful treatment in neonates without exchange transfusion, even with severe anemia. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

The article presents obituaries for several notable people including an orthopaedic surgeon James Geddis Kernohan, consultant orthopaedic surgeon Philip Victor Seal, and general practitioner Gordon Robert Winter.