A more critical role for silicon in the catalytic Staudinger amidation: silanes as non-innocent reductants

Amides are ubiquitous in organic chemistry and occur in some of the most important natural and non-natural molecules such as peptides, pharmaceuticals and polymers.1 For this reason, amidation reactions are some of the most frequently carried out procedures in chemical synthesis.2 Amidation reactions between azides and carboxylic acid derivatives have found widespread application owing to the fact that they can be deployed in varied and complex reaction media.3,4,5 While many of these methods use carboxylic acid-derived activated esters, the phosphine-mediated amidation reaction between free acids and azides was reported in 1983 by Garcia and co-workers (Scheme 1A).6 The utility of the process is undermined somewhat by the production of triphenylphosphine oxide as a stoichiometric by-product. However, this problem was overcome in 2012 by Ashfeld and co-workers who reported a catalytic, traceless Staudinger ligation reaction (Scheme 1B).7 This process represents a combination of Garcia’s amidation with the work of O’Brien,8 who was the first to demonstrate chemoselective phosphine oxide reduction with phenylsilane in the context of a catalytic Wittig reaction.9–14 Given that the catalytic reaction was constructed on this basis, the authors proposed a catalytic cycle (Scheme 1C) involving two key steps: (a) phosphorus-mediated amidation via an aminophosphonium carboxylate and the reactive N,O-phosphorane; and (b) chemoselective silane-mediated phosphine oxide reduction to return the phosphine catalyst. While these two steps are established as discrete processes, their conflation into a catalytic cycle presents an intriguing chemoselectivity issue, namely the reduction of triphenylphosphine oxide in the presence of reductively labile iminophosphorane, aminophosphonium and N,O-phosphorane intermediates.1

Measles: how many hospitalised cases are we missing?

We aimed to determine whether the Victorian measles surveillance system had missed hospitalised cases of measles during an inter-epidemic period. We searched the Victorian Inpatient Minimum Dataset (VIMD) for the period 1 January 1997 to 30 June 1998 to identify patients with ICD-9 discharge codes for measles (055). The data were compared with that held in the Victorian measles surveillance dataset. The hospital case notes of patients identified in the VIMD but not in the measles surveillance dataset were reviewed systematically to determine whether the patients met case definitions for laboratory-confirmed or clinically compatible measles. Sixteen admissions (15 patients) were identified with a measles ICD-9 code. Eight patients were not identified in the measles surveillance dataset. Of these, one was a laboratory confirmed case of measles and two met a clinical case definition but all should have been notified to the Department of Human Services as suspected cases. While the small number of missed notifications is encouraging in terms of overall measles surveillance, it highlights important deficiencies in the awareness of hospital staff of their role in the control of measles, particularly as Australia moves towards the elimination of measles

Distribution of giardia duodenalis assemblages A and B among children living in a remote Indigenous Community of the Northern Territory, Australia

Giardiasis is a communicable gastrointestinal disease caused by Giardia duodenalis and two genetic assemblages, A and B, cause human infection. In remote Indigenous communities of Australia, giardiasis is highly prevalent among children but disease transmission is poorly understood. This study investigated the prevalence of Giardia and genetic subtypes contributing to human disease in a remote Indigenous community, in the Northern Territory of Australia. Eighty-seven faecal samples were collected from 74 children (<15 years) over an 18 month period, and the distribution of positive cases relative to participant age and gender were examined. Screening by microscopy and 18S rRNA PCR amplification showed 66.7% (58/87) of faecal samples were positive for Giardia. Both males and females were equally affected and high detection rates were obtained for participants aged 0–<5 years and 5–<10 years (66.0 and 60.0% respectively). For 58.6% of the positive samples, Giardia was only detected by 18S rRNA PCR. Approximately 75% of cases were assemblage B, and subassemblage analyses using terminal restriction fragment length polymorphism of the glutamate dehydrogenase gene demonstrated that a variety of genetic variants were present. The high proportion of positive cases that were not detectable by microscopy, and dominance of assemblage B cases highlights the need for further research in this community, to assess the contribution of Giardia to chronic gastrointestinal disease among children, and to understand conditions conductive to assemblage B transmission

Mumps and rubella surveillance in Victoria, 1993 to 2000

Despite improving childhood coverage of the measles-mumps-rubella vaccine (MMR) in Victoria during the 1990s, mumps and rubella notifications in age groups eligible for vaccination persisted. This study reviewed the mumps and rubella surveillance data from 1993 to 2000 with a specific focus on method of diagnosis. There were 474 notifications of mumps over the seven-year period (annual median 61, range 40 to 77) and 3,544 notifications of rubella (annual median 297, range 66 to 1,165). The highest notifications rates for mumps were consistently among the 1-4 and 5-9 year age groups, whereas there was a marked change in the age distribution of rubella notifications during this interval. A large rubella outbreak occurred in 1995 with 1,165 notifications; the highest notification rates were males aged 15-24 years, infants under one year of age (males and females), and those aged 5-14 years (males and females), respectively. The susceptibility of 5-24 year olds reflects historical changes to the Australian Standard Vaccination Schedule. Rubella notifications returned to baseline levels in 1998 with the highest notification rates in infants aged under one year, and children aged 1-4 years. For both mumps and rubella, the majority of notifications for all age groups were clinically diagnosed, and were most common in children. Commun Dis Intell 2003;27:94-99

What parents in Australia know and do about head lice

INTRODUCTION: Although parents in developed market economies regard head lice infections (pediculosis) as a significant problem, health departments generally rate pediculosis as a low priority health issue, encouraging parents to manage and control it. But how well equipped and willing are parents to manage the infections? There do not appear to be any studies in the literature addressing these issues. This article presents the results of a survey conducted in Australia that aimed to answer these questions. METHODS: A cross-sectional survey of parents of primary school aged children in Victoria (Vic) and north Queensland (NQ) was conducted using a self-administered questionnaire. The study investigated the knowledge, attitudes and practices of parents regarding head lice infections. RESULTS: Only 7.1% of 1338 who completed the questionnaire answered all 10 knowledge questions correctly and more than one-third failed to answer half correctly. There was a weak negative correlation between parents\u27 knowledge and the prevalence of active pediculosis in the school. Almost all parents wanted the responsibility for treating pediculosis and more than three-quarters saw it as a health concern. A higher proportion of parents in NQ used preventative strategies (67% vs 41%). Most parents spent less than AU$50 per year on treatments. Alarmingly, however, the proportion of children missing school as a result of pediculosis was 24.4% and 30.3% in Vic and NQ, respectively. In Vic there was a positive correlation (r = 0.39) between missing school in the previous 12 months and prevalence of pediculosis in the school. CONCLUSIONS: This appears to be the most comprehensive study of parental knowledge, beliefs, and practices regarding head lice infections. Although parents wanted responsibility for the management of pediculosis, deficiencies in their knowledge indicate they may be inadequately equipped to do so. Given the high proportion of children in both states who have missed school as a result of head lice, it is recommended that health departments in Australia should work to ensure that consistent and accurate messages about pediculosis are disseminated, and that relevant legislation is amended to prevent children being excluded from school