Different steroids co-regulate long-term expansion versus terminal differentiation in primary human erythroid progenitors

Outgrowth, long-term self-renewal, and terminal maturation of human erythroid progenitors derived from umbilical cord blood in serum-free medium can be modulated by steroid hormones. Homogeneous erythroid cultures, as characterized by flow cytometry and dependence on a specific mixture of physiologic proliferation factors, were obtained within 8 days from a starting population of mature and immature mononuclear cells. Due to previous results in mouse and chicken erythroblasts, the proliferation-promoting effect of glucocorticoids was not unexpected. Surprisingly, however, androgen had a positive effect on the sustained expansion of human female but not male erythroid progenitors. Under optimal conditions, sustained proliferation of erythroid progenitors resulted in a more than 10(9)-fold expansion within 60 days. Terminal erythroid maturation was significantly improved by adding human serum and thyroid hormone (3,5,3'-triiodothyronine [T3]) to the differentiation medium. This resulted in highly synchronous differentiation of the cells toward enucleated erythrocytes within 6 days, accompanied by massive size decrease and hemoglobin accumulation to levels comparable to those in peripheral blood erythrocytes. Thus, obviously, different ligand-activated nuclear hormone receptors massively influence the decision between self-renewal and terminal maturation in the human erythroid compartment.     

Cardiac valves in patients with Whipple endocarditis: microbiological, molecular, quantitative histologic, and immunohistochemical studies of 5 patients

The pathological features of Whipple endocarditis, which is caused by Tropheryma whipplei, were histologically evaluated in cardiac valves from 5 patients. We used quantitative image analysis to compare the valvular fibrosis, calcifications, vegetations, inflammation, and vascularization due to Whipple endocarditis with those due to non-Whipple endocarditis and degenerative valves. We also studied the presence of T. whipplei in valves by immunohistochemical analysis, culture, and polymerase chain reaction (PCR). In histologic analysis, Whipple endocarditis was characterized by significant fibrosis, a lack of calcifications, slight inflammation and vascularization, and vegetations of intermediate size. Inflammatory infiltrates consisted mainly of foamy macrophages and lymphocytes. We found that the detection of T. whipplei in cardiac valves, by immunohistochemical analysis, was correlated with the detection of the bacterium by culture and PCR. We report, for the first time, the immunodetection of T. whipplei in a surgically removed arterial embolus. Pathological and immunohistologic analyses may contribute to the diagnosis of Whipple endocarditis.     

Antiretroviral treatments used among adults with HIV infection in Europe

International guidelines for the treatment of human immunodeficiency virus (HIV) infection change rapidly. They are mainly based on results from large-scale randomized clinical trials, but also on hypotheses. The objective of the study was to look at the use of antiretrovirals (ARVs) in different HIV treatment centres in Europe. Between August 1996 and September 1997 self-administered anonymous questionnaires were distributed to persons with HIV infection at inpatient and outpatient departments in 11 European countries; 1,366 people completed the questionnaire. Important differences in use of ARVs were noted between different centres. Zidovudine was the drug that was used predominantly in all countries and by 77% of all patients; the use of didanosine, zalcitabine and stavudine differed widely. Use of ARVs was found to be lower for people who reported intravenous drug use (compared to homosexual transmission), people with a low education level, and those with a monthly income lower than 992 Euro. The use of a protease inhibitor containing ARV treatment regimen was significantly lower in the centres in the south of Europe. Between 1996 and 1997, many persons with HIV infection in Europe received a suboptimal ARV treatment regimen. Use of ARVs should be improved for intravenous drug users, persons with lower educational level and lower income.     

Prevalence and outcome of severe chronic obstructive pulmonary disease exacerbations caused by multidrug-resistant bacteria

PURPOSE OF REVIEW: A bacterial cause is found in about half of all severe chronic obstructive pulmonary disease exacerbations. The aim of this review is to discuss recent findings regarding prevalence, risk factors and outcome of severe chronic obstructive pulmonary disease exacerbations caused by multidrug-resistant bacteria. RECENT FINDINGS: According to the results of recent studies, multidrug-resistant bacteria represented a large proportion of bacteria isolated in chronic obstructive pulmonary disease exacerbations. Prior antibiotic treatment, prior endotracheal intubation, long-term inhaled or systemic corticosteroid use and severe impairment of lung function were identified as risk factors for severe chronic obstructive pulmonary disease exacerbations related to multidrug-resistant bacteria. Although the mortality rate was higher in patients with multidrug-resistant bacteria as compared with patients with other bacteria, multidrug resistance was not independently associated with mortality in these patients. Multidrug-resistant bacteria were, however, significantly associated with inappropriate initial antibiotic treatment. Higher rates of subsequent ventilator-associated pneumonia and mortality were found in patients with severe chronic obstructive pulmonary disease exacerbation who received inappropriate initial antibiotic treatment when compared with those who received appropriate treatment. SUMMARY: Further studies should determine whether administration of broad-spectrum antibiotic treatment could improve the outcome of patients with severe chronic obstructive pulmonary disease exacerbation caused by multidrug-resistant bacteria.     

Calculation of crystalline lens power using a modification of the Bennett method

We present a method for measuring lens power from extended depth OCT biometry, corneal topography, and refraction using an improvement on the Bennett method. A reduced eye model was used to derive a formula for lens power in terms of ocular distances, corneal power, and objective spherical equivalent refraction. An error analysis shows that the formula predicts relaxed lens power with a theoretical accuracy of ± 0.5 D for refractive error ranging from −10 D to + 10 D. The formula was used to calculate lens power in 16 eyes of 8 human subjects. Mean lens power was 24.3 D ± 1.7 D.OCIS codes: (170.4500) Optical coherence tomography, (170.4580) Optical diagnostics for medicine, (330.7325) Visual optics, metrology, (330.7326) Visual optics, modeling