Fat and muscle areas can be calculated from equations on the basis of upper arm circumference (C) and triceps skinfold thickness (TS). These equations assume a circular limb and muscle compartment and a symmetrically distributed fat rim: total upper arm area (TUA) = C2/(4 pi), upper arm muscle area (UMA) = [C - (TS x pi)2]/(4 pi), and upper arm fat area (UFA) = TUA - UMA. This traditional method underestimates the degree of adiposity. We propose that the unrolled fat rim is a rectangle whose length = C and width = TS/2. The following new indexes are based on this assumption: upper arm fat area estimate (UFE) = C x (TS/2), and upper arm muscle area estimate (UME) = TUA - UFE. To validate these equations, areas were measured with magnetic resonance imaging (MRI) in 28 children aged 9-15 y (17 control subjects and 11 obese subjects). Correlations between MRI and UFA and MRI and UFE were similar (r = 0.96 for both correlations in the control group and r = 0.84 and 0.82, respectively, in the obese group), but the areas assessed by MRI (13.8 cm2) were closer to UFE (12.4 cm2) than to UFA (11.2 cm2) in the control group as well as in the obese group (MRI = 48.7 cm2, UFE = 46.6 cm2, and UFA = 38.5 cm2). The limits of agreement between MRI and anthropometry were 5.7 +/- 5.8 cm2 for UFA and 0.6 +/- 5.0 cm2 for UFE, showing that UFA is not acceptable in most cases, whereas UFE measurements are close to MRI measurements. In conclusion, UFE and UME are simple and accurate indexes to assess body composition. French reference values are available from 1 mo to 17 y of age.

Human multipotent mesenchymal stromal cells (MSC) are isolated from a plethora of tissue sources for cell therapy purposes. In 2006, the International Society for Cellular Therapy (ISCT) published minimal guidelines to define MSC identity. Nevertheless, many independent studies demonstrated that cells meeting the ISCT criteria possessed heterogeneous phenotypes and functionalities, heavily influenced by culture conditions. In this study, human MSC derived from many adult (bone marrow and adipose tissue) or fetal (cord blood, Wharton’s jelly, umbilical cord perivascular compartment and amniotic fluid) tissues were investigated. Their immunophenotype was analyzed to define consistent source-specific markers by extensive flow cytometry analysis and real-time qRT-PCR. CD271+ subpopulations were detected in adult MSC, whereas NG2 was significantly more expressed in fetal MSC but failed validation on independent samples coming from an external laboratory. The highest number of CD271+ adult MSC were detected soon after isolation in serum-based culture conditions. Furthermore, heterogeneous percentages of CD271 expression were found in platelet lysate-based or serum-free culture conditions. Finally, CD271+ adult MSC showed high clonogenic and osteogenic properties as compared to CD271− cells. To conclude, in this phenotype-function correlation study CD271+ subpopulation confers heterogeneity on adult MSC, confirming the need of more specific markers to address MSC properties.

The bone marrow microenvironment is physiologically hypoxic with areas being as low as 1% O2, e.g. the stem cell niche. Acute myeloid leukaemia (AML) blasts misuse these bone marrow niches for protection by the local microenvironment, but also might create their own microenvironment. Here we identify IL-8 as a hypoxia-regulated cytokine in both AML cell lines and primary AML samples that is induced within 48 hours of severe hypoxia (1% O2). IL-8 lacked effects on AML cells but induced migration in mesenchymal stromal cells (MSC), an integral part of the bone marrow. Accordingly, MSC were significantly increased in AML bone marrow as compared to healthy bone marrow. Interestingly, mononuclear cells obtained from healthy bone marrow displayed both significantly lower endogenous and hypoxia-induced production of IL-8. IL-8 mRNA expression in AML blasts from 533 patients differed between genetic subgroups with significantly lower expression of IL-8 in acute promyelocytic leukaemia (APL), while in non APL-AML patients with FLT ITD had the highest IL-8 expression. In this subgroup, high IL-8 expression was also prognostically unfavourable. In conclusion, hypoxia as encountered in the bone marrow specifically increases IL-8 expression of AML, which in turn impacts niche formation. High IL-8 expression might be correlated with poor prognosis in certain AML subsets.

OBJECTIVES: To observe the evolution of intraabdominal adipose tissue (IAT) in obese prepubertal children, who did not change their degree of obesity during adolescence and to evaluate its relationship with metabolic risk indexes (RI). DESIGN: Longitudinal study of 16 obese adolescents (eight male and eight female) in whom relative body weight (RBW) did not change signi®cantly and pubertal development was completed during the study period. MEASUREMENTS: Magnetic resonance imaging (MRI) scan at lumbar level (L4) three times during a 4 y period. At basal and at four years biochemical assays for metabolic indexes. RESULTS: IAT did not differ signi®cantly over the three measurement times and showed signi®cant correlations between ®rst and second (r 0.66, P`0.005), ®rst and third (r 0.61, P`0.01) and second and third values (r 0.84, P`0.0001). Subcutaneous adipose tissue (SAT) increased signi®cantly from basal to third evaluation (P`0.002). At baseline, IAT correlated signi®cantly with lipids (total and LDL cholesterol r 0.72, P`0.004), while at the end of the study, IAT correlated positively with insulin (fasting insulin r 0.55, P`0.008, insulin area after oral glucose tolerance test (OGTT) r 0.60, P`0.03, fasting insulinaglucose r 0.67 P`0.006) and negatively with high density lipoprotein (HDL) cholesterol (r 7 0.55, P`0.04). CONCLUSIONS: Obesity achieved before puberty, and stable during adolescence, showed a relatively stable amount of IAT. In post pubertal children the relationship of IAT to clinically signi®cant risk factors resemble the pattern in obese adults.