Natural estrogens enhance the engraftment of human hematopoietic stem and progenitor cells in immunodeficient mice

Hematopoietic stem and progenitor cells (HSPC) are crucial in the maintenance of lifelong production of all blood cells. These stem cells are highly regulated to maintain homeostasis through a delicate balance between quiescence, self-renewal and differentiation. However, this balance is altered during the recovery after HSPC transplantation. Transplantation efficacy can be limited by inadequate hematopoietic stem cell number, poor homing, low level of engraftment, or limited self-renewal. As recent evidence indicates that estrogens are involved in regulating hematopoiesis, we sought to examine whether natural estrogens (estrone or E1, estradiol or E2, estriol or E3 and estetrol or E4) modulate human HSPC. Our results show that human HSPC subsets express estrogen receptors, and that signaling is activated by E2 and E4 on these cells. Additionally, these natural estrogens cause different effects on human progenitors in vitro. We found that both E2 and E4 expand human HSPC. However, E4 was the best tolerated estrogen and promoted cell cycling of human hematopoietic progenitors. Furthermore, we found that E2 and, more significantly, E4 doubled human hematopoietic engraftment in immunodeficient mice without altering other HSPC properties. Finally, the impact of E4 on promoting human hematopoietic engraftment in immunodeficient mice might be mediated through the regulation of mesenchymal stromal cells in the bone marrow niche. Collectively, our data demonstrate that E4 is well tolerated and enhances human reconstitution in immunodeficient mice directly, by modulating human hematopoietic progenitor properties, and indirectly, by interacting with the bone marrow niche. This might have particular relevance for improving hematopoietic recovery after myeloablative conditioning, especially when limited numbers of HSPC are available.     

Risk of progression to AIDS and death in women infected with HIV-1 initiating highly active antiretroviral treatment at different stages of disease

BACKGROUND: The optimal virologic and immunologic stage at which to initiate antiretroviral therapy in individuals infected with human immunodeficiency virus type 1 (HIV-1) is undefined. METHODS: Among 1054 HIV-1-infected women in a prospective cohort study, we determined the time from initiation of highly active antiretroviral treatment (HAART) to acquired immunodeficiency syndrome (AIDS) and death. RESULTS: Median follow-up was 3.4 years. Of 553 women without AIDS at HAART initiation, 62 (11%) developed AIDS. Compared with women with CD4(+) cell counts greater than 350/microL at HAART initiation, women with cell counts of 200 to 350/microL and less than 200/microL had relative hazards (RHs) for progression to AIDS of 0.93 (95% confidence interval [CI], 0.46-1.86) and 2.48 (95% CI, 1.39-4.42), respectively. Compared with those with HIV-1 RNA values less than 5000 copies/mL, women with 5000 to 50,000 copies/mL and greater than 50,000 copies/mL had RHs of 1.39 (95% CI, 0.74-2.64) and 2.09 (95% CI, 1.09-3.99), respectively. Among women with AIDS at HAART initiation (n = 501), RHs of death were 1.97 (95% CI, 0.84-4.66) and 3.35 (95% CI, 1.59-7.08) with CD4(+) cell counts of 200 to 350/microL and less than 200/microL, respectively, relative to those with greater than 350/microL, and 1.90 (95% CI, 0.84-4.30) and 3.70 (95% CI, 1.81-7.54) for those with HIV-1 RNA values of 5000 to 50,000 and greater than 50,000 copies/mL, respectively, relative to those with less than 5000 copies/mL. CONCLUSIONS: Progression to AIDS and death was predicted by pre-HAART values of less than 200/microL for CD4(+) cells and greater than 50,000 HIV-1 RNA copies/mL, indicating that deferral of HAART until the CD4(+) cell count is between 350 and 200/microL is a valid strategy in the clinical management of HIV-1 infection.     

Chloroquine-Resistant Plasmodium falciparum: Effect of Substrate on Chloroquine and Amodiaquin Accumulation

Glucose stimulates the high-affinity processes of chloroquine and amodiaquin accumulation in owl monkey erythrocytes infected with a chloroquine-susceptible strain of Plasmodium falciparum. Although these erythrocytes have greater ability to accumulate amodiaquin than chloroquine, glucose has relatively less effect on amodiaquin accumulation than on chloroquine accumulation. In contrast to these findings with chloroquine-susceptible P. falciparum, glucose stimulates amodiaquin but not chloroquine accumulation in erythrocytes infected with chloroquine-resistant P. falciparum. This lack of function of a substrate-dependent component of chloroquine accumulation distinguishes chloroquine-resistant from chloroquine-susceptible P. falciparum.     

Characterization of CTX-M and SHV extended-spectrum beta-lactamases and associated resistance genes in Escherichia coli strains of food samples in Tunisia

OBJECTIVES: To assess the occurrence of extended-spectrum beta-lactamases (ESBLs) in Escherichia coli isolates of faecal samples of animals (n = 40) and food samples (n = 38) obtained in Tunisia in 2006, and to characterize the type of ESBLs, their genetic environments and the associated resistance genes. METHODS: Samples were inoculated in supplemented media (2 mg/L cefotaxime) for isolation of broad-spectrum cephalosporin-resistant E. coli isolates (one isolate/sample). ESBLs and their genetic environments as well as integrons and their gene cassette composition were characterized by PCR and sequencing. RESULTS: ESBL-producing E. coli isolates were detected in 10 of the 38 food samples analysed (26%) and in none of the tested animal faecal samples. Genes found were as follows (number of isolates): bla(CTX-M-1) (5), bla(CTX-M-1) + bla(TEM-1b) (1), bla(CTX-M-14) + bla(TEM-1b) (2), bla(CTX-M-8) (1) and bla(SHV-5) (1). All ESBL-positive isolates showed unrelated PFGE patterns. ISEcp1 and IS903 were detected surrounding bla(CTX-M-14), and ISEcp1/IS26 and orf477 surrounding some of the bla(CTX-M-1) genes. Four of the ESBL-positive strains harboured class 1 integrons including different gene cassette combinations. CONCLUSIONS: ESBLs, mainly of the CTX-M class, are detected in E. coli of food origin in Tunisia, being the first time that this mechanism has been detected in food E. coli strains in Africa.