Amplification of Sca-1+ Lin- WGA+ cells in serum-free cultures containing steel factor, interleukin-6, and erythropoietin with maintenance of cells with long-term in vivo reconstituting potential

Normal murine bone marrow (BM) cells were sorted on the basis of low forward and orthogonal light scatter properties, Sca-1 expression (Sca- 1+), lack of staining with a cocktail of mature hematopoietic lineage markers (Lin-), and binding of wheat germ agglutinin (WGA+). This approach allowed the reproducible isolation of a very small subpopulation (0.037% +/- 0.023% of all nucleated BM cells) that was approximately 400-fold enriched in cells capable of reconstituting both lymphoid and myeloid lineages in lethally irradiated recipients. Transplantation of 30 or 10 of these Sca-1+Lin-WGA+ cells resulted in > or = to 20% donor-derived nucleated peripheral blood cells 3 months posttransplantation in 100% and 22% of the recipients, respectively. When Sca-1+Lin-WGA+ cells were cultured in serum-free medium supplemented with Steel factor, interleukin-6 (IL-6), and erythropoietin (with or without IL-3), a large increase in total cell number, including cells with an Sca-1+Lin-WGA+ phenotype was observed. Single cell cultures showed that 90% to 95% of the input cells underwent at least one division during the first 2 weeks and the remainder died. Interestingly, this proliferative response was not accompanied by a parallel increase in the number of cells with both lymphoid and myeloid repopulating potential in vivo, as quantitation of these by limiting dilution analysis showed they had decreased slightly (1.3-fold) but not significantly below the number initially present. These results demonstrate that Sca-1+Lin-WGA+ cells with long-term repopulating potential can be maintained for 2 weeks in a serum- and stroma cell-free culture, providing a simple in vitro system to study their behavior under well-defined conditions. The observed expansion of Sca-1+Lin-WGA+ cells in vitro without a concomitant increase in reconstituting cells also shows that extensive functional heterogeneity exists within populations of cells with this surface phenotype.     

Characterization and purification of a primitive hematopoietic cell type in adult mouse marrow capable of lymphomyeloid differentiation in long-term marrow "switch" cultures

In this report, we describe a modification of the assay for long-term culture-initiating cells (LTC-IC) that allows a subset of murine LTC-IC (designated as LTC-ICML) to express both their myeloid (M) and lymphoid (L) differentiative potentials in vitro. The modified assay involves culturing test cells at limiting dilutions on irradiated mouse marrow feeder layers for an initial 4 weeks under conditions that support myelopoiesis and then for an additional week under conditions permissive for B-lymphopoiesis. All of the clonogenic pre-B progenitors (colony-forming unit [CFU] pre-B) detected in such postswitch LTC appear to be the progeny of uncommitted cells present in the original cell suspension because exposure of lymphoid-restricted progenitors to myeloid LTC conditions for > or = 7 days was found to irreversibly terminate CFU-pre-B production and, in cultures initiated with limiting numbers of input cells (no progenitors of any type detected in > 70% of cultures 1 week after the switch), the presence of CFU-pre-B was tightly associated with the presence of myeloid clonogenic cells, regardless of the purity of the input population. Limiting dilution analysis of the proportion of negative cultures measured for different numbers of input cells showed the frequency of LTC-ICML in normal adult mouse marrow to be 1 per 5 x 10(5) cells with an enrichment of approximately 500-fold in the Sca-1+ Lin-WGA+ fraction, as was also found for competitive in vivo repopulating units (CRU) and conventionally defined LTC-IC. LTC-ICML also exhibited the same resistance to treatment in vivo with 5-fluorouracil (5-FU) as CRU and LTC-IC, thereby distinguishing these three populations from the great majority of both in vitro clonogenic cells and day 12 CFU-S. The ability to quantitate cells with dual lymphoid and myeloid differentiation potentials in vitro, without the need for their prior purification, should facilitate studies of totipotent hematopoietic stem cell regulation.     

Tricuspid regurgitation velocity and other biomarkers of mortality in children,adolescents and young adults with sickle cell disease in the United States: The PUSH study

In the US, mortality in sickle cell disease (SCD) increases after age 18-20 years. Biomarkers of mortality risk can identify patients who need intensive follow-up and early or novel interventions. We prospectively enrolled 510 SCD patients aged 3-20 years into an observational study in 2006-2010 and followed 497 patients for a median of 88 months (range 1-105). We hypothesized that elevated pulmonary artery systolic pressure as reflected in tricuspid regurgitation velocity (TRV) would be associated with mortality. Estimated survival to 18 years was 99% and to 25 years, 94%. Causes of death were known in seven of 10 patients: stroke in four (hemorrhagic two, infarctive one, unspecified one), multiorgan failure one, parvovirus B19 infection one, sudden death one. Baseline TRV ≥2.7 m/second (>2 SD above the mean in age-matched and gender-matched non-SCD controls) was observed in 20.0% of patients who died vs 4.6% of those who survived (P = .012 by the log rank test for equality of survival). The baseline variable most strongly associated with an elevated TRV was a high hemolytic rate. Additional biomarkers associated with mortality were ferritin ≥2000 μg/L (observed in 60% of patients who died vs 7.8% of survivors, P < .001), forced expiratory volume in 1 minute to forced vital capacity ratio (FEV1/FVC) <0.80 (71.4% of patients who died vs 18.8% of survivors, P < .001), and neutrophil count ≥10x10⁹/L (30.0% of patients who died vs 7.9% of survivors, P = .018). In SCD children, adolescents and young adults, steady-state elevations of TRV, ferritin and neutrophils and a low FEV1/FVC ratio may be biomarkers associated with increased risk of death.     

Antenatal determinants of oro-facial clefts in Southern Nigeria

Objectives

Cleft lip with or without cleft palate, is the most common serious congenital anomaly that affects the orofacial regions. The management and care of the cleft patient constitutes a substantial proportion of the workload of the Nigerian maxillofacial surgeon and allied specialties. Yet, there are no specific programmes targeted at this group. We believe that the findings of this study is capable of identifying useful interventions for designing programs that will lead to a reduction in the burden of orofacial cleft in Nigeria.

Methods

It was a transverse cross-sectional study that was undertaken at the Maxillofacial Units of the University of Benin Teaching Hospital and the Central Hospital, Benin City respectively. The prevalence and antenatal determinants of cleft lip and palate were determined.

Results

Cleft lip and palate were often encountered in clinical practice in Benin City with a prevalence of 1.35%. The results showed that orofacial clefts were commoner in females and that the combined unilateral cleft lip and palate was the commonest entity encountered amongst the cases. The following risk factors were associated with the risk of development of cleft lip and palate: Paternal age >40 years, maternal age >35 years, genetic/family history, low socio-economic status, alcohol consumption and indulgence in the intake of herbal medications in pregnancy.

Conclusion

Public health education programmes and advocacy activities geared towards raising awareness of the identified risk factors for the development of cleft lip and or cleft palate would go a long way to obviate the occurrence and reduce the burden.Key Words: Prevalence, Antenatal determinants, orofacial clefts, Southern Nigeria     

Ventricular hypertrophy increases NT-proBNP in subjects with and without hypertension

BACKGROUND: It has been published that hypertension (HT) must be taken into account when using NT-proBNP, but left ventricular (LV) hypertrophy without HT could be a cause of NT-proBNP elevation. In a population study we compared NT-proBNP in subjects with hypertrophy, with and without diagnosis of HT. METHODS: We studied 215 subjects from a random sample of 432 people who had declared to suffer from dyspnea. These 432 subjects were referred to their hospital where blood samples were taken, an echo-Doppler study was performed and a specific questionnaire was completed. We got a positive answer from 215, and 52 (24%) have LV hypertrophy. RESULTS: When we compared NT-proBNP in non-hypertrophic population, 148 +/- 286 pg/ml, with NT-proBNP in LV hypertrophic population, 202 +/- 209 pg/ml, we found P < 0.001. In the hypertrophic group, when we compared NT-proBNP (199 +/- 201 pg/ml) in normotensive subjects (LV mass index 170 +/- 70 g/m2, Vp 50 +/- 18 cm/s, LVEF 62 +/- 8) with NT-proBNP (205 +/- 220 pg/ml) in subjects with diagnosis of HT (LV mass index 169 +/- 37 g/m2, Vp 55 +/- 20 cm/s, LVEF 64 +/- 10), we found NS. CONCLUSIONS: This population study shows that NT-proBNP is elevated in patients with LV hypertrophy with or without HT. In LV hypertrophy the presence of HT does not influence the peptide levels significantly.     

Assessing Advanced Communication Skills via Objective Structured Clinical Examination: A Comparison of Faculty Versus Self,Peer, and Standardized Patient Assessors

Abstract

Construct: The construct addressed in this study is assessment of advanced communication skills among senior medical students. Background: The question of who should assess participants during objective structured clinical examinations (OSCEs) has been debated, and options discussed in the literature have included peer, self, standardized patient, and faculty assessment models. What is not known is whether same-level peer assisted learning can be utilized for formative assessment of advanced communication skills when no faculty, standardized patients, or other trained assessors are involved in providing feedback. If successful, such an educational model would optimize resource utilization and broaden the scope of topics that could be covered in formative OSCEs. Approach: The investigators developed a 4-station formative OSCE focused on advanced communication skills for senior medical students, and evaluated the concordance of assessment done by same-level peers, self, standardized patients, and faculty for 45 students. After each station, examinees completed a self-assessment checklist and received checklist-based assessment and verbal feedback from same-level peers only. Standardized patients completed checklist-based assessments outside the room, and faculty did so after the OSCE via video review; neither group provided direct feedback to examinees. The investigators assessed inter-rater agreement and mean difference scores on the checklists using faculty score as the gold standard. Findings: There was fair to good overall agreement among self, same-level peer, standardized patient, and faculty-assessment of advanced communication skills. Relative to faculty, peer and standardized patient assessors overestimated advanced communication skills, while self-assessments underestimated skills. Conclusions: Self and same-level peer-assessment may be a viable alternative to faculty assessment for a formative OSCE on advanced communication skills for senior medical students.