Functional properties of hemoglobin in human red cells. I. Oxygen equilibrium curves and DPG binding

Oxygen equilibrium curves (OEC) for human red blood cells (RBC) have revealed a large asymmetry with an nmax value reached at approximately 90% saturation. This contrasts with the symmetrical shape of the OEC for diluted HbA solutions. We prepared resealed red blood cells (RRBC) through controlled hemolysis and resealing in order to obtain a low Hb concentration (approximately equal to 60 g/L) and DPG/Hb4 molar ratio ranging from 0.2 to 4. When the DPG/Hb4 was close to unity, OEC still showed a large asymmetry. On the contrary, the OEC became symmetrical when DPG/Hb4 was either negligible or 3-4 fold the normal value. The asymmetrical OEC for intact RBC can be fitted with a theoretical model taking into account the variations of free DPG concentration during oxygenation. We conclude that the asymmetrical shape of OEC observed in intact fresh RBC is not due to the high protein concentration present in the RBC but to a functional heterogeneity of Hb due to the changes of the free 2,3-diphosphoglycerate (DPG) concentration during oxygenation.     

Amphotropic or Gibbon Ape Leukemia Virus Retrovirus Binding and Transduction Correlates with the Level of Receptor mRNA in Human Hematopoietic Cell Lines

ABSTRACT: The low level of amphotropic retrovirus mediated gene transfer into human hematopoietic stem cells (HSC) has been an impediment to gene therapy for hematopoietic diseases (1). We have previously shown that mouse and human HSC have low levels of the mRNA encoding PiT-2, the amphotropic retrovirus receptor. We hypothesized that the low level of PiT-2 mRNA was responsible for the low frequency of transduction of HSC by amphotropic retroviral vectors (2). In this study we compared the level of PiT-2 and PiT-1, the Gibbon Ape Leukemia Virus receptor (GaLV), in 5 human tissue culture cell lines. PiT-2 and PiT-1 mRNA levels were highest in K562 cells and lowest in HL60 cells. In hematopoietic cell lines, the level of PiT-2 or PiT-1 mRNA correlated directly with retrovirus binding and transduction with the appropriate (amphotropic or GaLV) retrovirus vector. The level of expression of PiT-2 and PiT-1 mRNA could be increased by treatment of HL60 cells with either PMA or Interleukin-1α. The increase in the level of PiT-2 and PiT-1 mRNA correlated with increased transduction with both amphotropic and GaLV retroviral vectors. We conclude that the improved transduction was a direct effect of the increased levels of receptor mRNA and unrelated to changes in the cell cycle status.     

Pulmonary tolerance of prophylactic aerosolized pentamidine in human immunodeficiency virus-infected patients

The effects of primary and secondary long-term prophylaxis of Pneumocystis carinii pneumonia with aerosolized pentamidine on pulmonary function in HIV+ patients were evaluated. Eighty-one patients, none of whom were drug addicts or had pulmonary Kaposi's sarcoma, were studied. Fifty patients were receiving AP as secondary prophylaxis, 36 monthly and 14 twice-monthly; eight patients with a history of PCP served as control subjects. Twenty-three patients were receiving AP as primary prophylaxis, 12 monthly and 11 twice-monthly. Pulmonary function tests, including spirometry, lung transfer capacity for carbon monoxide (Tlco) and alveolar-arterial oxygen gradient (P[A-a]O2) were evaluated at M1, ie, one month after the diagnosis of PCP, or at the beginning of the AP prophylaxis, and then at three-month intervals (M4 to M13). No differences were observed in the results of spirometry or P(A-a)O2. Among the patients receiving secondary prophylaxis, a significant increase (paired Student's t-test) in Tlco occurred at M7 compared to M1 in the group receiving monthly administrations (p less than 0.01) and in the untreated control group (p less than 0.05); there was no significant difference in Tlco at M13 compared to M1 in the 12 patients who received monthly administrations for this period or at M7 in the 14 patients receiving AP twice-monthly. No significant difference in Tlco was observed at M7 in the primary prophylaxis groups. These results indicate that pulmonary tolerance of AP, as reflected by pulmonary function tests, is good.     

17β-Estradiol and estrogen receptor α protect right ventricular function in pulmonary hypertension via BMPR2 and apelin

Women with pulmonary arterial hypertension (PAH) exhibit better right ventricular (RV) function and survival than men; however, the underlying mechanisms are unknown. We hypothesized that 17β-estradiol (E2), through estrogen receptor α (ER-α), attenuates PAH-induced RV failure (RVF) by upregulating the procontractile and prosurvival peptide apelin via a BMPR2-dependent mechanism. We found that ER-α and apelin expression were decreased in RV homogenates from patients with RVF and from rats with maladaptive (but not adaptive) RV remodeling. RV cardiomyocyte apelin abundance increased in vivo or in vitro after treatment with E2 or ER-α agonist. Studies employing ER-α–null or ER-β–null mice, ER-α loss-of-function mutant rats, or siRNA demonstrated that ER-α is necessary for E2 to upregulate RV apelin. E2 and ER-α increased BMPR2 in pulmonary hypertension RVs and in isolated RV cardiomyocytes, associated with ER-α binding to the Bmpr2 promoter. BMPR2 is required for E2-mediated increases in apelin abundance, and both BMPR2 and apelin are necessary for E2 to exert RV-protective effects. E2 or ER-α agonist rescued monocrotaline pulmonary hypertension and restored RV apelin and BMPR2. We identified what we believe to be a novel cardioprotective E2/ER-α/BMPR2/apelin axis in the RV. Harnessing this axis may lead to novel RV-targeted therapies for PAH patients of either sex.     

Temporal and Spatial Compartmentalization of Drug-Resistant Cytomegalovirus (CMV) in a Child with CMV Meningoencephalitis: Implications for Sampling in Molecular Diagnosis

We describe a case of antiviral-resistant cytomegalovirus meningoencephalitis occurring after hematopoietic stem cell transplantation. Antiviral-resistant cytomegalovirus was identified in blood 16 months earlier. However, wild-type cytomegalovirus was evidenced in blood when the meningoencephalitis was diagnosed. Treatment of meningoencephalitis should be adapted to all previously identified resistance mutations in any compartment.