Stratigraphy of stable isotope ratios and leaf structure within an African rainforest canopy with implications for primate isotope ecology.

The canopy effect describes vertical variation in the isotope ratios of carbon (δ13C), oxygen (δ18O) and partially nitrogen (δ15N) within plants throughout a closed canopy forest, and may facilitate the study of canopy feeding niches in arboreal primates. However, the nuanced relationship between leaf height, sunlight exposure and the resulting variation in isotope ratios and leaf mass per area (LMA) has not been documented for an African rainforest. Here, we present δ13C, δ18O and δ15N values of leaves (n = 321) systematically collected from 58 primate food plants throughout the canopy (0.3 to 42 m) in Côte d'Ivoire, West Africa. Besides leaf sample height and light availability, we measured leaf nitrogen and carbon content (%N, %C), as well as LMA (n = 214) to address the plants' vertical resource allocations. We found significant variation in δ13C, δ18O and δ15N, as well as LMA in response to height in combination with light availability and tree species, with low canopy leaves depleted in 13C, 18O and 15N and slightly higher in %N compared to higher canopy strata. While this vertical isotopic variation was not well reflected in the δ13C and δ15N of arboreal primates from this forest, it did correspond well to primate δ18O values.

The role of early colposcopy in the management of females with first episode anogenital warts.

212 females attending a genitourinary medicine (GUM) clinic with first episode anogenital warts were screened by cervical cytology and colposcopy/histology for the presence of cervical epithelial abnormalities in keeping with infection by the human papillomavirus (HPV infection) and/or cervical intraepithelial neoplasia (CIN). The prevalence of cervical epithelial abnormalities detected by cervical cytology alone was 32%, rising to 56% after colposcopic examination. However, the majority of cervical lesions detected by colposcopy alone were of low grade (HPV infection and/or CIN I). Histologically-confirmed high grade cervical lesions (CIN II or CIN III) were detected more frequently in those females in whom cervical cytological examination indicated dyskaryosis in keeping with any grade of CIN, compared to females without dyskaryotic changes on cervical smear (P < 0.05, chi-squared test with Yates' correction). Early colposcopy is indicated for females with anogenital warts in the presence of a cervical smear showing dyskaryosis in keeping with any grade of CIN, because of the statistically significant increased risk of detecting a potentially progressive high grade cervical lesion. In females without dyskaryotic changes on cervical smear, the value of early colposcopy is uncertain and warrants larger more long-term trials.