Season, Terrestrial Ultraviolet Radiation, and Markers of Glucose Metabolism in Children Living in Perth, Western Australia.

Seasonality in glucose metabolism has been observed in adult populations; however, little is known of the associations between season and glucose metabolism in children. In this study, we examined whether markers of glucose metabolism (fasting glucose, insulin and HbA1c) varied by season in a paediatric population (6-13 years of age) located in Perth (Western Australia, n = 262) with data categorised by weight. Linear regression was used to analyse the nature of the relationships between mean daily levels of terrestrial ultraviolet radiation (UVR) (prior to the day of the blood test) and measures of glucose metabolism. Fasting blood glucose was significantly lower in autumn compared to spring, for children in combined, normal and obese weight categories. Fasting insulin was significantly lower in autumn and summer compared to winter for individuals of normal weight. HbA1c was significantly higher in summer (compared with winter and spring) in overweight children, which was in the opposite direction to other published findings in adults. In children with obesity, a strong inverse relationship (r = -0.67, p = 0.002) was observed for fasting glucose, and daily terrestrial UVR levels measured in the previous 6 months. Increased safe sun exposure in winter therefore represents a plausible means of reducing fasting blood sugar in children with obesity. However, further studies, using larger paediatric cohorts are required to confirm these relationships.

Cytokeratin 5/6 in normal human breast: lack of evidence for a stem cell phenotype.

In recent studies, Böcker and colleagues described a population of cells in paraffin wax sections of normal human breast that express cytokeratins (CK) 5/6 without expression of CK8/18 or smooth muscle actin (SMA). They proposed that these represent stem cells that give rise to differentiated luminal and myoepithelial cells. The data have been used to generate a model for breast cancer progression and classification with associated implications for management of pre-invasive disease. In this study, the expression of CK5/6, CK8/18, and SMA was investigated using multiple immunofluorescence on matched pairs of paraffin wax-embedded and frozen breast specimens. The staining patterns reported previously in antigen-retrieved paraffin wax-embedded sections were confirmed but no CK5/6-only cells were found in frozen sections of normal breast. There were cells with low levels of CK8/18 expression in frozen sections that may correspond to the CK8/18 'negative' cells seen in paraffin wax sections. This study brings into question the previously described profile of breast 'stem cells' based on CK5/6 staining and hence the breast cancer progression model and classification based on this phenotype.