The photochemical ring-opening of 1,3-cyclohexadiene imaged by ultrafast electron diffraction.

The ultrafast photoinduced ring-opening of 1,3-cyclohexadiene constitutes a textbook example of electrocyclic reactions in organic chemistry and a model for photobiological reactions in vitamin D synthesis. Although the relaxation from the photoexcited electronic state during the ring-opening has been investigated in numerous studies, the accompanying changes in atomic distance have not been resolved. Here we present a direct and unambiguous observation of the ring-opening reaction path on the femtosecond timescale and subångström length scale using megaelectronvolt ultrafast electron diffraction. We followed the carbon-carbon bond dissociation and the structural opening of the 1,3-cyclohexadiene ring by the direct measurement of time-dependent changes in the distribution of interatomic distances. We observed a substantial acceleration of the ring-opening motion after internal conversion to the ground state due to a steepening of the electronic potential gradient towards the product minima. The ring-opening motion transforms into rotation of the terminal ethylene groups in the photoproduct 1,3,5-hexatriene on the subpicosecond timescale.

Innovative strategies to improve diabetes outcomes in disadvantaged populations.

Diabetes disproportionately affects disadvantaged populations. Eighty percent of deaths directly caused by diabetes occurred in low- and middle-income countries. In high-income countries, there are marked disparities in diabetes control among racial/ethnic minorities and those with low socio-economic status. Innovative, effective and cost-effective strategies are needed to improve diabetes outcomes in these populations. Technological advances, peer educators and community health workers have expanded methodologies to reach, educate and monitor individuals with diabetes. In the present manuscript we review the outcomes of these strategies, and describe the barriers to and facilitators of these approaches for improving diabetes outcomes.

Zero tolerance of violence by users of mental health services: the need for an ethical framework.

Concerns about violent conduct of service users towards healthcare staff have prompted a ;zero tolerance' policy within the National Health Service. This policy specifically excludes users of mental health services. We attempt to challenge artificial distinctions between users of mental health and other services, and propose an ethical underpinning to the implementation of this policy.

Production of 6-deoxy-13-cyclopropyl-erythromycin B by Saccharopolyspora erythraea NRRL 18643.

Cyclopropane carboxylic acid was fed to Saccharopolyspora erythraea NRRL 18643 (6-deoxyerythromycin producer), resulting in the production of 6-deoxy-13-cyclopropyl-erythromycin B. These studies provide further evidence that deoxyerythronolide B synthase has a relaxed specificity for the starter unit.

A three-centre prospective pilot study to elucidate the effect of uvulopalatopharyngoplasty on patients with mild obstructive sleep apnoea due to velopharyngeal obstruction.

In this paper we describe the outcome of a prospective study designed to investigate the role of uvulopalatopharyngoplasty in the management of mild obstructive sleep apnoea. A group of 21 patients fulfilling strict inclusion and exclusion criteria underwent uvulopalatopharyngoplasty performed by a single surgeon using a modified technique. Specifically designed daily pain questionnaires were completed by the patients for 2 weeks after surgery and the morbidity associated with the procedure was assessed at 2, 6 and 12 weeks after operation. Thirteen of the 21 patients underwent a postoperative sleep study at 3 months after operation. The outcome measures used were the apnoea/hypopnoea index, the minimum O2 saturation, the sleep arousal index, the sleep architecture the Epworth Sleepiness Scale score, the subjective improvement in both the patient's and their partner's sleep and the morbidity associated with uvulopalatopharyngoplasty. We conclude that the patients with mild obstructive sleep apnoea most likely to obtain significant benefit from uvulopalatopharyngoplasty are those with a body mass index of between 27 and 30 with no cephalometric disproportion, those with frequent arousals not associated with periodic limb movements, those whose sleep related breathing disorder is not positional and most importantly those with symptomatic day time sleepiness.

Novel avermectins produced by mutational biosynthesis.

Avermectins with a wide range of novel C-25 substituents have been prepared by feeding carboxylic acids or their biosynthetic precursors to a Streptomyces avermitilis mutant strain ATCC 53568. This organism lacks the ability to form isobutyric and S-2-methylbutyric acids from their 2-oxo acid precursors and thus is unable to produce natural avermectins unless supplied with these acids. The novel avermectins produced by mutational biosynthesis possess broad-spectrum antiparasitic activity.

UK-63,052 complex, new quinomycin antibiotics from Streptomyces braegensis subsp. japonicus; taxonomy, fermentation, isolation, characterisation and antimicrobial activity.

UK-63,052 complex, a new group of quinomycin-like antibiotics comprising UK-63,052 (factor A), UK-63,598 (factor C), UK-65,662 (factor B) and several uncharacterised minor components, is produced by a new subspecies of the genus Streptomyces for which the name Streptomyces braegensis Dietz subsp. japonicus, is proposed. The strain, N617-29, is characterised by a negative melanin reaction, grey aerial mycelium, spiral spore chains and smooth or slightly warty spores. Structure determination has identified UK-63,052, C56H68N10O14S2, UK-63,598, C53H62N10O14S2 and UK-65,662, C55H66N10O14S2 as quinaldic acid substituted quinomycins with unusual bridgehead sulfur substitution as shown in Fig. 3.