A new approach to understanding tourism practices.

In spite of renewed attention for practices in tourism studies, the analysis of practices is often isolated from theories of practice. This theoretical paper identifies the main strands of practice theory and their relevance and application to tourism research, and develops a new approach to applying practice theory in the study of tourism participation. We propose a conceptual model of tourism practices based on the work of Collins (2004), which emphasises the role of rituals in generating emotional responses. This integrated approach can focus on individuals interacting in groups, as well as explaining why people join and leave specific practices. Charting the shifting of individuals between practices could help to illuminate the dynamics and complexity of tourism systems.

Head and neck squamous cell carcinoma from an unknown primary site.

BACKGROUND: The purpose of this study is to present our experience treating patients with squamous cell carcinoma (SCC) from an unknown head and neck primary site and to determine whether a policy change eliminating the larynx and hypopharynx from the radiotherapy (RT) portals has impacted outcome. METHODS: One hundred seventy-nine patients received definitive RT with or without a neck dissection for SCC from an unknown head and neck primary site. RT was delivered to the ipsilateral neck alone or both sides of the neck and, usually, the potential mucosal primary sites. The median mucosal dose was 5670 cGy. The median neck dose was 6500 cGy. One hundred nine patients (61%) received a planned neck dissection. RESULTS: Mucosal control at 5 years was 92%. The mucosal control rate in patients with RT limited to the nasopharynx and oropharynx was 100%. The 5-year neck-control rates were as follows: N(1), 94%; N(2a), 98%; N(2b), 86%; N(2c), 86%; N(3), 57%; and overall, 81%. The 5-year cause-specific survival rates were as follows: N(1), 94%; N(2a), 88%; N(2b), 82%; N(2c), 71%; N(3), 48%; and overall, 73%. The 5-year overall survival rates were as follows: N(1), 50%; N(2a), 70%; N(2b), 59%; N(2c), 45%; N(3), 34%; and overall, 52%. Eleven patients (7%) developed severe complications. CONCLUSION: RT alone or combined with neck dissection results in a high probability of cure with a low risk of severe complications. Eliminating the larynx and hypopharynx from the RT portals did not compromise outcome and likely reduces treatment toxicity.

Acetylcholinesterase from the invertebrate Ciona intestinalis is capable of assembling into asymmetric forms when co-expressed with vertebrate collagenic tail peptide.

To learn more about the evolution of the cholinesterases (ChEs), acetylcholinesterase (AChE) and butyrylcholinesterase in the vertebrates, we investigated the AChE activity of a deuterostome invertebrate, the urochordate Ciona intestinalis, by expressing in vitro a synthetic recombinant cDNA for the enzyme in COS-7 cells. Evidence from kinetics, pharmacology, molecular biology, and molecular modeling confirms that the enzyme is AChE. Sequence analysis and molecular modeling also indicate that the cDNA codes for the AChE(T) subunit, which should be able to produce all three globular forms of AChE: monomers (G(1)), dimers (G(2)), and tetramers (G(4)), and assemble into asymmetric forms in association with the collagenic subunit collagen Q. Using velocity sedimentation on sucrose gradients, we found that all three of the globular forms are either expressed in cells or secreted into the medium. In cell extracts, amphiphilic monomers (G(1)(a)) and non-amphiphilic tetramers (G(4)(na)) are found. Amphiphilic dimers (G(2)(a)) and non-amphiphilic tetramers (G(4)(na)) are secreted into the medium. Co-expression of the catalytic subunit with Rattus norvegicus collagen Q produces the asymmetric A(12) form of the enzyme. Collagenase digestion of the A(12) AChE produces a lytic G(4) form. Notably, only globular forms are present in vivo. This is the first demonstration that an invertebrate AChE is capable of assembling into asymmetric forms. We also performed a phylogenetic analysis of the sequence. We discuss the relevance of our results with respect to the evolution of the ChEs in general, in deuterostome invertebrates, and in chordates including vertebrates.