References and cutoffs for triceps and subscapular skinfolds in Norwegian children 4-16 years of age.

BACKGROUND/OBJECTIVES: To establish new reference values for triceps (TSF) and subscapular (SSF) skinfolds of Norwegian children 4-16 years of age, and to define cutoff values for overweight and obesity using the criteria of the International Obesity Task Force (IOTF). SUBJECTS/METHODS: A cross-sectional sample of 4606 children 4-16 years of age, part of a larger growth study, was used to estimate reference curves with the LMS method; suggested cutoffs were selected using receiver operating characteristic analyses. RESULTS: Reference values for TSF and SSF are presented as percentiles. Mean skinfold size increased with age. Girls had higher values than boys over the entire age range. There was a strong positive correlation between both skinfolds and body mass index (BMI). For all ages together, a cutoff of 1.0 standard deviation score (SDS) gave a sensitivity of 76% for SSF, and 70% for TSF to detect overweight, with a corresponding specificity of 92% for both. To detect obesity, a cutoff value of 1.3 SDS gave a sensitivity of 91% and specificity of 90% for SSF. Corresponding values for TSF were 86% for the sensitivity, and 91% for the specificity. CONCLUSIONS: This study presents new reference values for TSF and SSF skinfolds in Norwegian children 4-16 years of age. Both skinfolds had a high-discriminating power to detect overweight and obesity as defined by the IOTF BMI criteria.

Waist circumference and waist-to-height ratio in Norwegian children 4-18 years of age: reference values and cut-off levels.

AIM: To establish reference values for waist circumference and waist-to-height ratio of Norwegian children. MATERIAL: Data were collected in 2003-2006 as part of a cross-sectional study, including 5725 children 4-18 years of age. Reference curves were fitted with the LMS method; appropriate cut-offs were selected using receiver operating characteristic analysis. RESULTS: Reference values for waist circumference and waist-to-height ratio are presented. Mean waist circumference increased with age for both genders. Boys had a higher waist circumference at almost all ages. Mean waist-to-height ratio decreased until early adolescence and thereafter increased slightly towards adult age. There was a strong positive correlation between waist circumference and BMI (r = 0.907, p < 0.01) and a moderate positive correlation between waist-to-height ratio and BMI (r = 0.397 p < 0.01). A waist circumference cut-off value of 1.0 SDS (85th percentile) gave a sensitivity of 79% and a specificity of 94% to detect overweight. A cut-off value of 1.6 SDS (95th percentile) gave a sensitivity of 94% and a specificity of 96% to detect obesity. CONCLUSION: This study presents the first reference values of waist circumference and waist-to-height ratio for Norwegian children 4-18 years, which also represent the first reference in Scandinavian schoolchildren. The 85th and 95th percentiles of waist circumference are proposed as appropriate cut-offs for central overweight and obesity.

Antibodies to eukaryotic, including autologous, native DNA are produced during BK virus infection, but not after immunization with non-infectious BK DNA.

The contemporary view concerning the origin of anti-dsDNA antibodies is that eukaryotic dsDNA is not immunogenic. Results presented here, however, show (1) that inoculation of rabbits with BK virus elicits antibodies to eukaryotic, including autologous, dsDNA, (2) that the transition from a non-immunogenic to an immunogenic state of autologous dsDNA depends on productive infection with BK virus, and (3) that inoculation with protein-free circular BK dsDNA initiates both infection in vivo and production of antibodies to autologous dsDNA. Non-infectious linearized BK dsDNA did not elicit any anti-dsDNA antibodies, while the same DNA molecule, when complexed with methylated bovine serum albumin, elicited anti-dsDNA antibodies solely recognizing BK dsDNA. Neither of the two linearized BK dsDNA preparations initiated infection. Using two different techniques, we could demonstrate that two separate sets of anti-dsDNA antibodies were produced during viral infection; one recognizing BK dsDNA, and the other recognizing autologous dsDNA. Thus, in contrast to previous assumptions, autologous dsDNA may be immunogenic. Based on the present results, we propose that autologous dsDNA can be rendered immunogenic through complex formation with viral DNA binding protein(s) such as the structural protein VP1 or the tumour antigen T. Such DNA-protein complexes may bypass a putative T-cell tolerance to autologous dsDNA.

Antibodies to viral and mammalian native DNA in response to BK virus inoculation and subsequent immunization with calf thymus DNA.

Recent studies have demonstrated that anti-DNA antibodies share important genetical features with antibodies to exogenous antigens, suggesting that anti-DNA antibody responses may be (auto-) antigen driven. We have earlier defined three out of five rabbits as anti-dsDNA antibody responders based on reactivity with calf thymus (CT) dsDNA after inoculation with the human dsDNA virus BK. In the present study we demonstrate that all five animals that received BK virus inoculations produced antibodies to BK virus dsDNA. These antibodies did not cross-react with CT dsDNA, as shown by inhibition experiments. The anti-BK dsDNA antibodies persisted over time, in contrast to the anti-CT dsDNA antibodies that decreased shortly after a peak following the first boost of BK virus. While the anti-CT dsDNA antibodies decreased, the anti-BK dsDNA antibodies remained elevated, thus supporting the results of the inhibition experiments which showed that two independent antibody populations are produced after BK virus inoculations. In the three animals producing anti-mammalian dsDNA antibodies, antibodies recognizing CT dsDNA reappeared after intravenous administration of a complex of CT dsDNA and methylated bovine serum albumin (MBSA) without adjuvant. The latter anti-CT dsDNA antibodies did not cross-react with BK dsDNA. In contrast to earlier studies we conclude that mammalian dsDNA may be immunogenic, and that discrete molecular differences in DNA antigens from different sources may induce anti-dsDNA antibodies specific for dsDNA molecules of different origin.