Autoradiographic and scintillation analysis of 5-aminolevulinic acid permeation through epithelialised tissue: Implications for topical photodynamic therapy of superficial gynaecological neoplasias

Purpose. Aminolevulinic acid (5-ALA) diffusion through both keratinised and non-keratinised tissue, used as a model tissue substrates, was evaluated, together with the depth of permeation and the concentration achieved following delivery from bioadhesive patch and proprietary cream formulations. Materials and Methods. Moisture-activated, bioadhesive patches loaded with 5-ALA at concentrations of 19.0, 38.0 and 50.0 mg cm(-2) and an o/w cream (20% w/w 5-ALA) were radiolabelled with C14 5-ALA and applied to excised human vaginal tissue and porcine skin. After 1, 2 and 4 h, tissue was sectioned in two orientations and the 5-ALA concentration at specific depths determined using autoradiography and liquid scintillation counting (LSC). Results. The stratum corneum was a significant barrier to 5-ALA permeation, with concentrations in tissue dependent on application time and drug loading. 5-ALA was detected at 6 mm using autoradiography after 2 h, with LSC showing phototoxic concentrations at 2.375 mm after 4 h of application. Inclusion of oleic acid and dimethyl sulphoxide in bioadhesive patches increased 5-ALA significantly in neonate porcine tissue, but only for patches cast from blends containing 5% w/w oleic acid. Conclusions. The bioadhesive patch described delivered 5-ALA to depths of at least 2.5 mm in tissue types indicative of vulval skin, suggesting that photodynamic therapy of deep vulval intraepithelial neoplasia is feasible using this means of bioadhesive 5-ALA delivery.

HPV prevalence and type-distribution in cervical cancer and premalignant lesions of the cervix: A population-based study from Northern Ireland

Assessment of Human papillomavirus (HPV) prevalence and genotype distribution is important for monitoring the impact of prophylactic HPV vaccination. This study aimed to demonstrate the HPV genotypes predominating in pre-malignant and cervical cancers in Northern Ireland (NI) before the vaccination campaign has effect. Formalin fixed paraffin embedded tissue blocks from 2,303 women aged 16-93 years throughout NI were collated between April 2011 and February 2013. HPV DNA was amplified by PCR and HPV genotyping undertaken using the Roche^® linear array detection kit. In total, 1,241 out of 1,830 eligible samples (68.0%) tested positive for HPV, with the majority of these [1,181/1,830 (64.5%)] having high-risk (HR) HPV infection; 37.4% were positive for HPV-16 (n=684) and 5.1% for HPV-18 (n=93). HPV type-specific prevalence was 48.1%, 65.9%, 81.3%, 92.2%, and 64.3% among cervical intraepithelial neoplasias (CIN) Grades I-III, squamous cell carcinomas (SCC) and adenocarcinoma (AC) cases, respectively. Most SCC cases (81.3%) had only one HPV genotype detected and almost a third (32.0%) of all cervical pathologies were HPV negative including 51.9% of CIN I (n=283), 34.1% CIN II (n=145), 18.7% of CIN III (n=146), 7.8% of SCC (n=5), and 35.7% of AC (n=5) cases. This study provides important baseline data for monitoring the effect of HPV vaccination in NI and for comparison with other UK regions. The coverage of other HR-HPV genotypes apart from 16 and 18, including HPV-45, 31, 39, and 52, and the potential for cross protection, should be considered when considering future polyvalent vaccines.