The RAR-RXR as well as the RXR-RXR pathway is involved in signaling growth inhibition of human CD34+ erythroid progenitor cells

Previous studies have shown that retinoic acid (RA), similar to tumor necrosis factor-alpha (TNF-alpha), can act as a bifunctional regulator of the growth of bone marrow progenitors, in that it can stimulate granulocyte-macrophage colony-stimulating factor (GM-CSF)- or interleukin-3 (IL-3)-induced GM colony formation, but potently inhibit G-CSF-induced growth. The present study, using highly enriched human CD34+ as well as Lin- murine bone marrow progenitor cells, demonstrates a potent inhibitory effect of 9-cis-RA on burst-forming unit-erythroid (BFU-E) colony formation regardless of the cytokine stimulating growth. Specifically, 9-cis-RA potently inhibited the growth of BFU-E response to erythropoietin (Epo) (100%), stem cell factor (SCF) + Epo (92%), IL- 3 + Epo (97%), IL-4 + Epo (88%), and IL-9 + Epo (100%). Erythroid colony growth was also inhibited when CD34+ progenitors were seeded at one cell per well, suggesting a direct action of RA. Using synthetic ligands to retinoic acid receptors (RARs) and retinoid X receptors (RXRs) that selectively bind and activate RAR-RXR or RXR-RXR dimers, respectively, we dissected the involvement of the two retinoid response pathways in the regulation of normal myeloid and erythroid progenitor cell growth. Transactivation studies showed that both the RAR (Ro 13- 7410) and RXR (Ro 25-6603 and Ro 25-7386) ligands were highly selective at 100 nmol/L. At this concentration, Ro 13-7410 potently inhibited G- CSF-stimulated myeloid as well as SCF + Epo-induced erythroid colony growth. At the same concentration, Ro 25-6603 and Ro 25-7386 had little or no effect on G-CSF-induced colony formation, whereas they inhibited 75% and 53%, respectively, of SCF + Epo-stimulated BFU-E colony growth. Thus, the RAR-RXR response pathway can signal growth inhibition of normal bone marrow myeloid and erythroid progenitor cells. In addition, we demonstrate a unique involvement of the RXR-RXR pathway in mediating growth inhibition of erythroid but not myeloid progenitor cells.     

Lipopolysaccharide enhances CD11b/CD18 function but inhibits neutrophil aggregation

Human neutrophils are primed in the presence of complexes of lipopolysaccharide (LPS) with its serum binding protein (LBP) in a manner dependent on CD14. Cellular consequences of priming include increased responsiveness, the upregulation of surface proteins including the adhesive integrin CD11b/CD18 (Mac-1), the increased binding of certain ligands to CD11b/CD18, and the concurrent shedding of the L-selectin homing receptor. Because expression of both CD11b/CD18 and L-selectin is obligatory for formyl peptide-stimulated neutrophil aggregation in vitro (Simon et al, Blood 82:1097, 1993), we have examined the consequences of bacterial endotoxin on the expression of neutrophil adhesive molecules. We observed that the exposure of neutrophils to LPS/LBP, while enhancing the surface numbers and adhesive function of CD11b/CD18 for latex particles, did not induce aggregation. In contrast, as the LPS/LBP concentration increased (ED50 = 30 ng/mL LPS/LBP), the ability of neutrophils to aggregate decreased in parallel with the shedding of L-selectin. Moreover, when L-selectin adhesive activity was blocked by treatment with Fab fragments of Dreg- 200, aggregation was inhibited to an extent roughly proportional to the available L-selection. Blocking of LPS/LBP with CD14-specific monoclonal antibodies suppressed L-selectin shedding and preserved formyl peptide-stimulated aggregation. Taken together, the data suggest that inhibition of neutrophil aggregation by LPS/LBP is related to the expression of L-selectin via CD14 rather than LPS inhibition of CD11b/CD18 function during cellular stimulation.     

Functional differences between CD38- and DR- subfractions of CD34+ bone marrow cells

Several studies have previously demonstrated enrichment in primitive progenitor cells in subfractions of CD34+ bone marrow (BM) cells not expressing CD38 or HLA-DR (DR) antigens. However, no studies have directly compared these two cell populations with regard to their content of primitive and more committed progenitor cells. Flow cytometric analysis of immunomagnetic isolated CD34+ cells demonstrated little overlap between CD34+CD38- and CD34+DR- progenitor subpopulations in that only 12% to 14% of total CD34+DR- and CD34+CD38- cells were double negative (CD34+CD38-DR-). Although the number of committed myeloid progenitor cells (colony-forming units granulocyte- macrophage) was reduced in both subpopulations, only CD34+CD38- cells were significantly depleted in committed erythroid progenitor cells (burst-forming units-erythroid). In single-cell assay, CD34+CD38- cells showed consistently poorer response to single as opposed to multiple hematopoietic growth factors as compared with unfractionated CD34+ cells, indicating that the CD34+CD38- subset is relatively enriched in primitive hematopoietic progenitor cells. Furthermore, CD34+CD38- and CD34+DR- cells, respectively, formed 3.2-fold and 1.6-fold more high proliferative potential colony-forming cell (HPP-CFC) colonies than did unfractionated CD34+ cells. Finally, CD34+CD38-DR- cells were depleted in HPP-CFCs as compared with CD34+CD38+DR+ cells. The results of the present study suggest that both the CD38- and DR- subfractions of CD34+ bone marrow cells are enriched in primitive hematopoietic progenitor cells, with the CD34+CD38- subpopulation being more highly enriched than CD34+DR- cells.     

Bifunctional effects of tumor necrosis factor alpha (TNF alpha) on the growth of mature and primitive human hematopoietic progenitor cells: involvement of p55 and p75 TNF receptors

Tumor necrosis factor alpha (TNF alpha) has previously been reported to have both inhibitory and stimulatory effects on hematopoietic progenitor cells. Specifically, TNF alpha has been proposed to stimulate early hematopoiesis in humans. In the present study we show that TNF alpha, in a dose-dependent fashion, can potently inhibit the growth of primitive high proliferative potential colony-forming cells (HPP-CFCs) stimulated by multiple cytokine combinations. Using agonistic antibodies to the p55 and p75 TNF receptors or TNF alpha mutants specific for either of the two TNF receptors, we show that both receptors can mediate this inhibition. In contrast, the potent stimulation of interleukin-3 (IL-3) plus granulocyte-macrophage colony- stimulating factor (GM-CSF) induced HPP-CFC colony formation observed at low concentrations of TNF alpha (2 ng/mL) was only a p55-mediated event. Moreover, the stimulatory effects of TNF alpha on GM-CSF or IL-3- induced colony formation, as well as the inhibition of G-CSF-induced colony growth, were also exclusively signaled through the p55 TNF receptor. Taken together, our results suggest that the inhibitory effects of TNF alpha on primitive bone marrow progenitor cells are mediated through both p55 and p75 TNF receptors, whereas the p55 receptor exclusively mediates the bidirectional effects on more mature, single factor-responsive bone marrow progenitor cells as well as stimulation of IL-3 plus GM-CSF-induced HPP-CFC colony growth.     

Prognostic discrimination in "good-risk" chronic granulocytic leukemia

The prognostic significance of disease features recorded at the time of diagnosis was examined among 813 patients with Philadelphia chromosome- positive, nonblastic chronic granulocytic leukemia (CGL) collected from six European and American series. The survival pattern for this population was typical of "good-risk" patients, and median survival was 47 mo. There were multiple interrelationships among different disease features, which led to highly significant correlations with survival for some that had no primary prognostic significance, such as hematocrit. Multivariable regression analysis indicated that spleen size and the percentage of circulating blasts were the most important prognostic indicators. These features, and age, behaved as continuous variables with progressively unfavorable import at higher values. The platelet count did not influence survival significantly at values below 700 X 10(9)/liter but was increasingly unfavorable above this level. Basophils plus eosinophils over 15%, more than 5% marrow blasts, and karyotypic abnormalities in addition to the Ph1 were also significant unfavorable signs. The Cox model, generated with four variables representing percent blasts, spleen size, platelet count, and age, provided a useful representation of risk status in this population, with good fit between predicted and observed survival over more than a twofold survival range. A hazard function derived from half of the patient population successfully segregated the remainder into three groups with significantly different survival patterns. We conclude that it should be possible to identify a lower risk group of patients with a 2-yr survival of 90%, subsequent risk averaging somewhat less than 20%/yr and median survival of 5 yr, an intermediate group, and a high- risk group with a 2-yr survival of 65%, followed by a death rate of about 35%/yr and median survival of 2.5 yr.     

Can we measure the ankle-brachial index using only a stethoscope? A pilot study

Background. Ankle-brachial index (ABI) is an excellent methodfor the diagnosis of peripheral arterial disease (PAD) whenit is performed with Doppler. However, this device is not alwaysavailable for primary care physicians. The ABI measured withstethoscope is an easy alternative approach, but have not beenproved to be useful. Objective. To assess the accuracy of the ABI measured usinga stethoscope comparatively to that of the current eligiblemethod for the diagnosis of PAD, the Doppler ABI, and describethe characteristics of this new approach. Methods. We conducted a diagnostic study of ABI measured witha stethoscope and a Doppler probe and compared the results.Eighty-eight patients were accessed by both methods. Results. Mean stethoscope ABI, 1.01 ± 0.15, and meanDoppler ABI, 1.03 ± 0.20, (P = 0.047) displayed a goodcorrelation. Measurements of stethoscope ABI diagnostic accuracyin recognizing a Doppler ABI are described. The comparison ofthis data with the current gold standard method results gavea sensitivity of 71.4% [95% confidence interval (CI), 41.9–91.6]and specificity of 91.0% (95% CI, 81.5–96.6), with predictivepositive value of 62.5% (95% CI, 38.6–81.5) and negativepredictive value of 93.8% (95% CI, 85.2–97.6). The studyaccuracy was 87.7%. The area under the ROC curve was 0.895 (95%CI, 0.804–0.986, P < 0.0001). Conclusions. According to our study, the stethoscope ABI isa useful method to detect PAD and it may be suitable for itsscreening in the primary care setting. Keywords. Ankle-brachial index, peripheral arterial disease, stethoscope.     

Human parvo-virus B19 infection among children with sickle cell anaemia in Jos,North Central Nigeria

Objective:Human Parvovirus B19 is known to cause significant morbidity and mortality and among diverse patient population groups.Among patients with sickle all disease,who have high red cell turn over due to chronic haemolysis,infection with parvovirus B19 can cause severe life threatening transient aplastic crisis.This study was conducted to determine the Seroprevalence of parvovirus B19 infection and to provide basic epidemiological data on parvovirus B19 infection among children with sickle cell anaemia in Jos,north central Nigeria.Methods: In a hospital based cross sectional survey,200 children aged 1-18 years confirmed to have sickle cell anaemia attending the paediatric sickle cell clinic of Jos university teaching hospital were studied.A questionnaire was designed to obtain basic socio-demographic information,& other relevant aspect of patients′ history.Blood samples were taken for anti parvo-virus B19 serology.Results: The over all prevalence rates of parvo-virus B19 immunoglobulin(IgG) and immunoglobulin(IgM) antibodies were 39.5% and 3.5% respectively,Conclusion: This study confirms that parvo-virus B19 infection is prevalent among children with sickle cell anaemia in Jos,North Central Nigeria.There is a need for further studies to fully evaluate the clinical impact of the infection on our sickle cell anaemia patients.     

Active tuberculosis and Mycobacterium tuberculosis latent infection in patients with HIV/AIDS

Objectives

Tuberculosis (TB) remains an important disease associated with HIV infection and AIDS in Brazil, even in a setting of free access to antiretroviral therapy (ART) and TB treatment. In previous studies, isoniazid therapy (IT) for latent infection with Mycobacterium tuberculosis (LIMTb) was found to reduce the risk of TB by 62% in patients with a tuberculin test (TT)>5 mm. The objectives of this study were to investigate the occurrence of TB, the prevalence of LIMTb and the coverage of the TT and IT, and to estimate the number of missed opportunities to prevent TB in patients with HIV/AIDS.

Methods

A random sample of patients with HIV/AIDS was selected; data from the medical files were obtained, and a TT was performed in consenting subjects.

Results

In the 203 subjects included in the study, TB occurrence was 13.3%, LIMTb prevalence was 20% and the coverage of the TT and IT was 59.2 and 55%, respectively. Patients with TB had a lower nadir CD4 cell count, but their CD4 recovery was comparable to that of non‐TB patients. Patients with LIMTb always had a higher CD4 cell count.

Conclusions

By expanding the coverage of the TT and IT to nearly 100%, we could more than double the number of prevented cases of TB. TB prevention programmes must be reinforced to reduce the number of missed opportunities for diagnosis, and IT must be improved to reduce TB among patients with HIV/AIDS. Empowering patients with knowledge about TB, the preventive role of IT and the need for an annual TT may be the best way of lowing rates of TB in patients with HIV/AIDS.     

Validity and reliability of a Swedish version of the Non‐Communicating Children’s Pain Checklist – Postoperative Version

Aim: To test the validity and reliability of a Swedish version of the Non‐Communicating Children’s Pain Checklist – Postoperative Version (NCCPC‐PV). Methods: Thirty‐two consecutive children/adolescents (2–20 years of age) with cognitive impairment and no verbal communication from four habilitation centres were admitted to the study. Each child’s behaviour was observed by a parent or a caregiver and by a physiotherapist in two calm and two painful situations within the child’s everyday life. The raters independently assessed and graded the child’s behaviour during 5 min according to the translated Swedish version of the NCCPC‐PV. The intrarater and interrater reliability were determined, and the construct validity was examined. Results: The results from 202 assessments showed that the construct validity was good: children’s behavioural signs differed significantly between situations of pain and situations of calm (p < 0.001). Repeated assessments showed poor agreement both within and between raters [intraclass correlation coefficient (ICC) 0.51–0.65]. The agreement for pain was good (ICC 0.83). Conclusion: The Swedish version of the NCCPC‐PV can be used for pain assessment in children with cognitive impairments who lack verbal communication. Aspects of reliability need to be further analysed.