Characterizing the multi-dimensional reaction dynamics of dihalomethanes using XUV-induced Coulomb explosion imaging.

Site-selective probing of iodine 4d orbitals at 13.1 nm was used to characterize the photolysis of CH2I2 and CH2BrI initiated at 202.5 nm. Time-dependent fragment ion momenta were recorded using Coulomb explosion imaging mass spectrometry and used to determine the structural dynamics of the dissociating molecules. Correlations between these fragment momenta, as well as the onset times of electron transfer reactions between them, indicate that each molecule can undergo neutral three-body photolysis. For CH2I2, the structural evolution of the neutral molecule was simultaneously characterized along the C-I and I-C-I coordinates, demonstrating the sensitivity of these measurements to nuclear motion along multiple degrees of freedom.

Photon Acceleration in a Flying Focus.

A high-intensity laser pulse propagating through a medium triggers an ionization front that can accelerate and frequency upshift the photons of a second pulse. The maximum upshift is ultimately limited by the accelerated photons outpacing the ionization front or the ionizing pulse refracting from the plasma. Here, we apply the flying focus-a moving focal point resulting from a chirped laser pulse focused by a chromatic lens-to overcome these limitations. Theory and simulations demonstrate that the ionization front produced by a flying focus can frequency upshift an ultrashort optical pulse to the extreme ultraviolet over a centimeter of propagation. An analytic model of the upshift predicts that this scheme could be scaled to a novel tabletop source of spatially coherent x rays.

The current and future role of the medical oncologist in the professional care for cancer patients: a position paper by the European Society for Medical Oncology (ESMO).

The number of cancer patients in Europe is rising and significant advances in basic and applied cancer research are making the provision of optimal care more challenging. The concept of cancer as a systemic, highly heterogeneous and complex disease has increased the awareness that quality cancer care should be provided by a multidisciplinary team (MDT) of highly qualified healthcare professionals. Cancer patients also have the right to benefit from medical progress by receiving optimal treatment from adequately trained and highly skilled medical professionals. Built on the highest standards of professional training and continuing medical education, medical oncology is recognised as an independent medical specialty in many European countries. Medical oncology is a core member of the MDT and offers cancer patients a comprehensive and systemic approach to treatment and care, while ensuring evidence-based, safe and cost-effective use of cancer drugs and preserving the quality of life of cancer patients through the entire 'cancer journey'. Medical oncologists are also engaged in clinical and translational research to promote innovation and new therapies and they contribute to cancer diagnosis, prevention and research, making a difference for patients in a dynamic, stimulating professional environment. Medical oncologists play an important role in shaping the future of healthcare through innovation and are also actively involved at the political level to ensure a maximum contribution of the profession to Society and to tackle future challenges. This position paper summarises the multifarious and vital contributions of medical oncology and medical oncologists to today's and tomorrow's professional cancer care.

Involvement in research activities and factors influencing research capacity among dietitians.

BACKGROUND: A healthcare professional's aptitude to develop research skills and actively engage in research is necessary to optimise healthcare efficacy. The present study investigated the factors that contribute to research capacity within the Australian dietetic workforce. METHODS: Queensland-based dietitians scored their department and individual skill or success in research on a 10-point scale using an anonymous online survey that incorporated the validated Research Capacity in Context tool. Descriptive statistics were assessed against geographical setting, dietetic experience and the proportion of role (Full Time Equivalent; FTE) designated to research. Research activities were defined by the number of items currently involved in or completed in the past 6 months (n = 11). Factors associated with research activities were assessed by multivariable linear regression. RESULTS: Dietitians (n = 130) identified having a moderate skill or success in 14 research items [mean (SD) 5.1 (1.7)] and perceived that their departments provided a moderate level of research support in 19 research items [mean (SD) 6.1 (2.5)]. Geographical setting, the proportion of role designated to research (FTE) and participation in research activities were associated with individual and department ratings of research skill or success. Research involvement was predicted by the proportion of role (FTE) designated to research (ß = 0.34, t = 4.16, P < 0.001) and years of experience in dietetics (ß = 0.32, t = 2.67, P < 0.009). CONCLUSIONS: A dietitian's capacity for research is related to professional experience and the designation of research in the role description. The findings of the present study will provide a baseline of research capacity and expertise among dietitians, and also inform the strategic development of building research capacity.

Domestic and travel-related foodborne gastrointestinal illness in a population health survey.

Routine surveillance data underestimate incidence of foodborne gastrointestinal (FGI) illness and provide little information on illness related to travel. We analysed data from the Welsh Health Survey to estimate population incidence, and to examine risk factors for FGI and factors associated with consulting a doctor. Reported frequency of any FGI in the 3 months before interview was 20.0% [95% confidence interval (CI) 19.5-20.4; equivalent to 0.8 episodes per person-year], and for travel-related FGI was 1.6% (95% CI 1.5-1.8). In the final model, sex, age group, marital status, self-reported health, long-term illness, smoking and alcohol consumption were all independent predictors of FGI. People who consulted a doctor were likely to be older, in poorer health, taking regular medication, or to report mental illness. FGI is common but risk factors for illness and consultation differ and impressions of the epidemiology of the disease based on surveillance data are therefore distorted.

A review of the microbiology, antibiotic usage and resistance in chronic skin wounds.

Chronic leg and foot wounds represent an increasing burden to healthcare systems as the age of the population increases. The deep dermal tissues of all chronic wounds harbour microorganisms, however, the precise interaction between microbes in the wounds and impaired healing is unknown. With regard to antibiotic therapy, there is a lack of evidence concerning its effectiveness, optimal regimens or clinical indications for treatment. Despite this lack of evidence, antibiotics are frequently a feature of the management of chronic wounds and these patients receive significantly more antibiotic prescriptions (both systemic and topical) than age and sex-matched patients. Current guidelines for antibiotic prescribing for such wounds are often based on expert opinion rather than scientific fact and may present difficulties in interpretation and implementation to the clinician. Although the increasing prevalence of antibiotic resistance is widely recognized, the relationships between antibiotic resistance, chronic wound microbiology and rationales for antibiotic therapy have yet to be determined. This review discusses the role of microbes in chronic wounds from a clinical perspective with particular focus on the occurrence of bacteria and their impact on such wounds. The evidence and role of antibiotics in the treatment of such wounds are outlined and current practice of antibiotic usage for chronic wounds in the primary care setting described. The implications of antibiotic usage with regard to antibiotic resistance are also considered.

Long-term impact of vaccination on Haemophilus influenzae type b (Hib) carriage in the United Kingdom.

A recent resurgence in serious infections due to Haemophilus influenzae type b (Hib) has been observed in the United Kingdom. More information on Hib transmission in the population is required in order to better understand the mechanism of this increase. The Public Health Laboratory Service (subsumed into the Health Protection Agency since April 2004) conducted four cross-sectional studies of asymptomatic oropharyngeal Hib carriage in children attending day-care nurseries in England and Wales in 1992, 1994, 1997 and 2002. These demonstrated a marked reduction in the prevalence of Hib colonization over time since vaccine introduction (3.98% in 1992; 0.70% in 1994; 0% in 1997; 0% in 2002), which did not explain the increase in invasive disease reports from 1999 onwards. We believe that a reduction in antibody levels over the first 5 years of life in immunized children in recent years has fuelled the rise in reported cases in the absence of an obvious increase in transmission.

Laboratory testing policies and their effects on routine surveillance of community antimicrobial resistance.

OBJECTIVE: To investigate the effects of laboratory testing policies, particularly selective testing, rule-based reporting and isolate identification, on estimates of community antimicrobial resistance. MATERIALS AND METHODS: Antibiotic resistance estimates were analysed from an all-Wales dataset for approximately 300 000 community isolates of common pathogens. RESULTS: Selective testing policies were often associated with markedly increased resistance, particularly for second-line testing. Site-specific testing tended to yield variant resistance estimates for eye and ear isolates. Estimates from rule-based reporting deviated markedly from test-result-based reporting. Urinary isolates reported as Escherichia coli showed greater susceptibility than those reported as undifferentiated urinary 'coliforms'. The proportion of isolates tested for an antibiotic by a laboratory was a useful indicator of selective testing in this dataset. Selective testing policies had invariably been applied where the proportion of isolates of a species tested against an antibiotic was <90%. As this proportion fell with increasingly selective policies, divergence from pooled-all-Wales non-selective estimates tended to increase, with a bias to increased resistance. CONCLUSIONS: Selective testing, rule-based reporting and urinary coliform identification policies all had significant effects upon resistance estimates. Triage based upon the proportion of isolates tested seemed a useful tool in assigning analysis resources. Where <20% of isolates were tested, selective policies with inherent bias to increased resistance were common, the low number of isolates gave high potential sampling errors, and little confidence could be placed in the resistance estimate. Where 20-90% of isolates were tested, detailed analysis sometimes revealed resistance estimates that might be usefully retrieved. Where >/=90% of isolates were tested, there was no evidence of selective testing, and inter-laboratory variation in estimates appeared to be safely ascribable to other effects, e.g. methodology or real variation in resistance levels.

X-Ray crystal structures of Candida albicans dihydrofolate reductase: high resolution ternary complexes in which the dihydronicotinamide moiety of NADPH is displaced by an inhibitor.

X-ray crystallographic analysis of 5-(4'-substituted phenyl)sulfanyl-2,4-diaminoquinazoline inhibitors in ternary complex with Candida albicans dihydrofolate reductase (DHFR) and NADPH revealed two distinct modes of binding. The two compounds with small 4'-substituents (H and CH3) were found to bind with the phenyl group oriented in the plane of the quinazoline ring system and positioned adjacent to the C-helix. In contrast, the more selective inhibitors with larger 4'-substituents (tert-butyl and N-morpholino) were bound to the enzyme with the phenyl group perpendicular to the quinazoline ring and positioned in the region of the active site that typically binds the dihydronicotinamide moiety of NADPH. The cofactor appeared bound to DHFR but with the disordered dihydronicotinamide swung away from the protein surface and into solution. This unusual inhibitor binding mode may play an important role in the high DHFR selectivity of these compounds and also may provide new ideas for inhibitor design.

The 1.2 A resolution structure of the Con A-dimannose complex.

The complex between concanavalin A (Con A) and alpha1-2 mannobiose (mannose alpha1-2 mannose) has been refined to 1.2 A resolution. This is the highest resolution structure reported for any sugar-lectin complex. As the native structure of Con A to 0.94 A resolution is already in the database, this gives us a unique opportunity to examine sugar-protein binding at high resolution. These data have allowed us to model a number of hydrogen atoms involved in the binding of the sugar to Con A, using the difference density map to place the hydrogen atoms. This map reveals the presence of the protonated form of Asp208 involved in binding. Asp208 is not protonated in the 0.94 A native structure. Our results clearly show that this residue is protonated and hydrogen bonds to the sugar. The structure accounts for the higher affinity of the alpha1-2 linked sugar when compared to other disaccharides. This structure identifies different interactions to those predicted by previous modelling studies. We believe that the additional data presented here will enable significant improvements to be made to the sugar-protein modelling algorithms.

Factors associated with antibiotic resistance in coliform organisms from community urinary tract infection in Wales.

Routine susceptibility data for urinary coliform isolates from community practice were analysed in comparison with dispensed antibiotic prescriptions for all conditions and social deprivation data for Bro Taf and North Wales Health Authorities for financial years 1996--1998. Prescribing rates and resistance rates varied widely between practices. Among isolates from practices with high usage of an antibiotic, rates of resistance to that antibiotic tended to be high, and usage correlated significantly with resistance between practice population units. Cross-correlations were found between usage of one antibiotic and resistance to another, particularly for trimethoprim and ampicillin. Usage, particularly of trimethoprim, was associated with multi-resistance to up to four antibiotics. Resistance was more frequent in isolates from males, children and the elderly. Ampicillin resistance correlated with social deprivation. Analyses including or excluding potential repeat isolates yielded closely similar results. Indices reflecting sampling behaviour (laboratory coliform positivity rates, positivity per 1000 registered patients, specimens submitted per 1000 registered patients) varied widely between surgeries, suggesting lack of consensus on urine sampling policies. These indices showed only weak correlations with usage or resistance. Associations between resistance and usage were compared for isolates from two patient subsets that were likely to differ in their proportions of non-Escherichia coli isolates: female patients aged 16--55 years; and males, children and patients aged >55 years. The latter showed higher base levels of resistance, but the associations of resistance with usage were statistically indistinguishable for the two populations. The results suggest that usage of antibiotics in a practice population may affect the rate of urinary infection caused by resistant coliform organisms in that population.

Crystal structure of dephospho-coenzyme A kinase from Haemophilus influenzae.

Dephospho-coenzyme A kinase catalyzes the final step in CoA biosynthesis, the phosphorylation of the 3'-hydroxyl group of ribose using ATP as a phosphate donor. The protein from Haemophilus influenzae was cloned and expressed, and its crystal structure was determined at 2.0-A resolution in complex with ATP. The protein molecule consists of three domains: the canonical nucleotide-binding domain with a five-stranded parallel beta-sheet, the substrate-binding alpha-helical domain, and the lid domain formed by a pair of alpha-helices. The overall topology of the protein resembles the structures of nucleotide kinases. ATP binds in the P-loop in a manner observed in other kinases. The CoA-binding site is located at the interface of all three domains. The double-pocket structure of the substrate-binding site is unusual for nucleotide kinases. Amino acid residues implicated in substrate binding and catalysis have been identified. The structure analysis suggests large domain movements during the catalytic cycle.

The 1.30 A resolution structure of the Bacillus subtilis chorismate mutase catalytic homotrimer.

The crystal structure of the Bacillus subtilis chorismate mutase, an enzyme of the aromatic amino acids biosynthetic pathway, was determined to 1.30 A resolution. The structure of the homotrimer was determined by molecular replacement using orthorhombic crystals of space group P2(1)2(1)2(1) with unit-cell parameters a = 52.2, b = 83. 8, c = 86.0 A. The ABC trimer of the monoclinic crystal structure [Chook et al. (1994), J. Mol. Biol. 240, 476-500] was used as the starting model. The final coordinates are composed of three complete polypeptide chains of 127 amino-acid residues. In addition, there are nine sulfate ions, five glycerol molecules and 424 water molecules clearly visible in the structure. This structure was refined with aniosotropic temperature factors, has excellent geometry and a crystallographic R factor of 0.169 with an R(free) of 0.236. The three active sites of the macromolecule are at the subunit interfaces, with residues from two subunits contributing to each site. This orthorhombic crystal form was grown using ammonium sulfate as the precipitant; glycerol was used as a cryoprotectant during data collection. A glycerol molecule and sulfate ion in each of the active sites was found mimicking a transition-state analog. In this structure, the C-terminal tails of the subunits of the trimer are hydrogen bonded to residues of the active site of neighboring trimers in the crystal and thus cross-link the molecules in the crystal lattice.

Biological function made crystal clear - annotation of hypothetical proteins via structural genomics.

Many of the gene products of completely sequenced organisms are 'hypothetical' - they cannot be related to any previously characterized proteins - and so are of completely unknown function. Structural studies provide one means of obtaining functional information in these cases. A 'structural genomics' project has been initiated aimed at determining the structures of 50 hypothetical proteins from Haemophilus influenzae to gain an understanding of their function. Each stage of the project - target selection, protein production, crystallization, structure determination, and structure analysis - makes use of recent advances to streamline procedures. Early results from this and similar projects are encouraging in that some level of functional understanding can be deduced from experimentally solved structures.

Susceptibility testing of Klebsiella spp.--an international collaborative study in quality assessment.

In order to compare the prevalence of antibiotic resistance in different geographical areas, it is necessary to ensure agreement between laboratories on the assignment of strains to 'susceptible' and 'resistant' categories. An international quality assessment was performed to investigate the performance of susceptibility testing of Klebsiella spp. Ninety-five strains of klebsiellae were selected from clinical isolates at the London Hospital Medical College (LHMC). These included strains with a diversity of susceptibility profiles to amoxycillin/clavulanate, piperacillin, ceftazidime, cefuroxime, ciprofloxacin, gentamicin and trimethoprim. The strains were sent to 13 participating laboratories in Europe and the USA and laboratories were asked to test the susceptibility of these strains to these antibiotics by their usual methods. They were also asked to provide details of the method used to test susceptibility. Several different standard recommended testing methods were used. Reporting of susceptibilities was generally accurate, but a number of anomalies were noted. Discrepancies of reporting between the LHMC and the participating laboratories was more marked for resistant strains, particularly in the detection of resistance to cefuroxime and ciprofloxacin, as well as the assignment of susceptibility and resistance to piperacillin and amoxycillin/clavulanate. Some discrepancies could be attributed to the use of different breakpoints, leading to differing assignment of susceptibility. Methodological variations including disc content, inoculum and failure to measure and interpret zone sizes consistently also led to anomalies. This quality assessment programme has helped to identify problems in susceptibility testing which should be investigated further.