Managing stakeholder concerns associated with releases of imported stock in insect control programmes.

A commitment to reducing pesticide use and the development of novel technologies are driving a renewed interest in insect-mediated pest and vector control programmes. Such programmes, along with conservation and pollination applications, lead to an increased transport volume of live insect stock. At release sites, concerns surrounding imported insects can be reduced by using local genotypes that have been mass-produced elsewhere. Remaining plausible concerns are likely to be centred on human factors (vector behaviour or capacity) and ecological factors (interacting species) and should be anticipated in the design of communication materials. Well-designed, locally relevant communication and engagement material is an important part of programme success. Stakeholder engagement is thus critical to reducing risks of perceived and plausible concerns affecting programme outcomes in an increasingly electronically connected world. Experience at release sites can help inform the design of accessible information useful at all stages of the transportation pathway. For transnationally transported insects, providing such information to specific stakeholders (e.g. courier companies and border authorities) will reduce the likelihood of delays, which can, in turn, affect the quality and mortality of the transported insects.

Les engagements pris en matière de réduction de l'utilisation de pesticides et les nouvelles technologies disponibles ont donné un nouvel essor aux programmes de contrôle des parasites et des vecteurs axés sur les insectes. Ces programmes, auxquels s'ajoutent d'autres applications destinées à favoriser la conservation et la pollinisation, se traduisent par un accroissement du volume de stocks d'insectes vivants transportés dans le monde. Dans les sites de destination des insectes transportés, les inquiétudes que peuvent susciter ces importations peuvent être tempérées en faisant appel à des génotypes locaux, produits en masse ailleurs puis réintroduits. D'autres préoccupations peuvent subsister, portant sur des facteurs humains (liées aux effets du comportement des vecteurs ou à leur capacité vectorielle) et écologiques (liées aux espèces en interaction) ; il convient d'anticiper ces inquiétudes lors de la conception des supports de communication. Des matériels de communication et de mobilisation bien conçus et prenant en compte le contexte local sont une composante importante de la réussite d'un programme. La participation des parties prenantes se révèle donc cruciale pour réduire le risque que des inquiétudes perçues et plausibles viennent affecter les résultats d'un programme dans un monde de plus en plus interconnecté par voie électronique. L'expérience acquise dans les sites de lâchers d'insectes peut contribuer à documenter la conception d'une information accessible, qui sera utile à chaque étape de la procédure de transport. Lorsqu'il s'agit d'insectes transportés au-delà des frontières nationales, la diffusion de ce type d'information à des intervenants spécifiques (par exemple, les sociétés de transport express et les autorités frontalières) permettra de limiter les circonstances entraînant des retards d'acheminement, car ceux-ci peuvent à leur tour affecter la qualité et la viabilité des insectes transportés.

El empeño de reducir el uso de plaguicidas y la aparición de tecnologías novedosas están alimentando un renovado interés por los programas de control de plagas y vectores mediante insectos. Este tipo de programas, junto con las aplicaciones de los insectos con fines de polinización o de protección ambiental, se traducen en el transporte de volúmenes crecientes de poblaciones de insectos vivos. Para apaciguar los recelos que despiertan los insectos importados en los sitios de suelta cabe recurrir al empleo de genotipos locales criados a gran escala en otro lugar. A la hora de concebir el material de comunicación es conveniente prever de antemano y tener en cuenta las suspicacias plausibles que aún puedan subsistir, que seguramente tendrán que ver con factores humanos (por ejemplo, preocupación por los posibles efectos del comportamiento o la capacidad vectorial del insecto introducido) o ecológicos (interacción con otras especies). El uso de material de comunicación y participación bien concebido y adaptado al contexto local es un ingrediente importante para el éxito de todo programa. La participación de las partes interesadas es pues fundamental para reducir los riesgos (ya sean imaginados o plausibles) que puedan afectar los resultados del programa, en un mundo que está cada vez más interconectado electrónicamente. La experiencia adquirida en los sitios de suelta puede ayudar a concebir material informativo accesible que sea de utilidad en todas las etapas del proceso de transporte. En el caso de los insectos transportados de un país a otro, el hecho de facilitar esta información a determinadas partes (como las empresas de transporte o las autoridades aduaneras) reducirá la probabilidad de demoras, cosa que a su vez incidirá en la calidad y la viabilidad de los insectos transportados.

Can there be a common, risk-based framework for decisions around live insect trade?

A network of scientists involved in shipment of live insects has met and generated a series of articles on issues related to live insect transport. The network is diverse, covering large-scale commercial interests, government operated areawide control programmes, biomedical research and many smaller applications, in research, education and private uses. Many insect species have a record of safe transport, pose minimal risks and are shipped frequently between countries. The routine shipments of the most frequently used insect model organism for biomedical research, Drosophila melanogaster, is an example. Successful large scale shipments from commercial biocontrol and pollinator suppliers also demonstrate precedents for low-risk shipment categories, delivered in large volumes to high quality standards. Decision makers need access to more information (publications or official papers) that details actual risks from the insects themselves or their possible contaminants, and should propose proportionate levels of management. There may be harm to source environments when insects are collected directly from the wild, and there may be harm to receiving environments. Several risk frameworks include insects and various international coordinating bodies, with experience of guidance on relevant risks, exist. All stakeholders would benefit from an integrated overview of guidance for insect shipping, with reference to types of risk and categories of magnitude, without trying for a single approach requiring universal agreement. Proposals for managing uncertainty and lack of data for smaller or infrequent shipments, for example, must not disrupt trade in large volumes of live insects, which are already supporting strategic objectives in several sectors.

À l'occasion d'une réunion d'experts, un réseau de chercheurs travaillant sur l'expédition d'insectes vivants a produit un ensemble d'articles traitant des questions liées au transport des insectes vivants. Ce réseau est diversifié et représente un large éventail d'intérêts privés et de programmes de lutte biologique à grande échelle menés par les pouvoirs publics, en plus du secteur de la recherche biomédicale et de nombreux acteurs intervenant dans des applications de plus petite envergure relevant de la recherche, de l'enseignement ou du secteur privé. Un grand nombre d'espèces d'insectes sont transportées en toute sécurité avec un niveau de risque minimal, y compris lors des fréquentes expéditions internationales. Un exemple de ces expéditions régulières concerne l'espèce la plus utilisée par la recherche biomédicale en tant qu'organisme modèle, à savoir Drosophila melanogaster. Les exemples réussis d'expéditions à grande échelle provenant de fournisseurs d'agents de lutte biologique et de pollinisateurs produits par le secteur privé offrent également un relevé documenté des diverses catégories d'expéditions à faible risque pour des livraisons d'insectes vivants en grandes quantités et répondant à des normes de qualité élevées. Les décideurs politiques devraient pouvoir accéder à plus d'informations (à travers des publications ou des articles officiels) décrivant en détail les risques réels associés aux insectes eux-mêmes ou à leurs contaminants éventuels, et proposer en connaissance de cause des niveaux de gestion proportionnels à ces risques. La récolte d'insectes prélevés directement de la nature peut être dommageable aussi bien pour les environnements source que pour ceux de destination. Plusieurs cadres fondés sur le risque intègrent désormais les insectes dans leurs directives. Par ailleurs, nombre d'organismes internationaux de coordination ont acquis une expérience dans l'élaboration de lignes directrices face à ces risques. Il serait bénéfique pour toutes les parties prenantes de disposer d'une vue d'ensemble intégrée des directives applicables aux expéditions d'insectes, qui recense les différents types de risque et leurs ordres de grandeur sans se prononcer sur une approche unique qui nécessiterait une adhésion universelle. Ni les propositions visant à gérer l'incertitude ni l'insuffisance des données disponibles sur les expéditions d'insectes en petits nombres ou occasionnelles ne doivent perturber les échanges commerciaux d'insectes vivants en grandes quantités, échanges qui participent aujourd'hui aux objectifs stratégiques de nombreux secteurs.

Una red de científicos relacionados de un modo u otro con el transporte de insectos vivos mantuvo un encuentro y generó una serie de artículos en torno a la cuestión. En la red, muy heterogénea, convergen desde intereses comerciales de gran calado hasta programas públicos de lucha biológica en grandes territorios, pasando por la investigación biomédica y por numerosas aplicaciones de menor dimensión en ámbitos como la investigación, la enseñanza u otros usos privados. Muchas especies de insectos cuentan con un buen historial de seguridad en el transporte, presentan un riesgo mínimo y son expedidas a menudo de un país a otro. Buen ejemplo de ello son los envíos sistemáticos de ejemplares de Drosophila melanogaster, que es el insecto utilizado con más frecuencia como organismo modelo en la investigación biomédica. Otro precedente de envíos voluminosos cuyo transporte y entrega se ajusta a los más exigentes criterios de calidad lo sientan las remesas de grandes cantidades de polinizadores y agentes de control biológico remitidos por proveedores comerciales. Los responsables de adoptar decisiones deben disponer de más y más detallada información (publicaciones o documentos oficiales) sobre los riesgos reales derivados de los propios insectos o sus posibles contaminantes para proponer a partir de ahí medidas de gestión proporcionadas. Los perjuicios ambientales pueden darse tanto en origen (cuando hay captura salvaje de insectos, o sea recolección directa en el medio) como en destino. Hay varios sistemas de determinación del riesgo que incluyen a los insectos y también existen diversos organismos de coordinación internacional que ya tienen experiencia en sentar pautas sobre los riesgos en la materia. Todos los interlocutores del sector se beneficiarían de una visión global e integrada del transporte de insectos, que remita a diferentes tipos de riesgo y categorías de magnitud, sin necesidad de buscar un sistema único que exija consenso universal. Las propuestas para gestionar la incertidumbre y la falta de información en el caso de envíos infrecuentes o de pequeñas dimensiones, por ejemplo, no deben interferir en el transporte de grandes cantidades de insectos vivos, que ya está sirviendo a objetivos estratégicos en varios sectores.

Effects of the removal or reduction in density of the malaria mosquito, Anopheles gambiae s.l., on interacting predators and competitors in local ecosystems.

New genetic control methods for mosquitoes may reduce vector species without direct effects on other species or the physical environment common with insecticides or drainage. Effects on predators and competitors could, however, be a concern as Anopheles gambiae s.l. is preyed upon in all life stages. We overview the literature and assess the strength of the ecological interactions identified. Most predators identified consume many other insect species and there is no evidence that any species preys exclusively on any anopheline mosquito. There is one predatory species with a specialisation on blood-fed mosquitoes including An. gambiae s.l.. Evarcha culicivora is a jumping spider, known as the vampire spider, found around Lake Victoria. There is no evidence that these salticids require Anopheles mosquitoes and will readily consume blood-fed Culex. Interspecific competition studies focus on other mosquitoes of larval habitats. Many of these take place in artificial cosms and give contrasting results to semi-field studies. This may limit their extrapolation regarding the potential impact of reduced An. gambiae numbers. Previous mosquito control interventions are informative and identify competitive release and niche opportunism; so while the identity and relative abundance of the species present may change, the biomass available to predators may not.

Using biological-physical modelling for informing sea lice dispersal in Loch Linnhe, Scotland.

Sea lice are a constraint on the sustainable growth of Scottish marine salmonid aquaculture. As part of an integrated pest management approach, farms coordinate procedures within spatial units. We present observations of copepodids being at relatively greater density than nauplii in upper waters, which informs the development of surface layer sea lice transmission modelling of Loch Linnhe, Scotland, for informing farm parasite management. A hydrodynamic model is coupled with a biological particle-tracking model, with characteristics of plankton sea lice. Simulations are undertaken for May and October 2011-2013, forced by local wind data collected for those periods. Particles are continually released from positions representing farm locations, weighted by relative farm counts, over a 2-week period and tracked for a further 5 days. A comparison is made between modelled relative concentrations against physical and biological surveys to provide confidence in model outputs. Connectivity between farm locations is determined in order to propose potential coordination areas. Generally, connectivity depends on flow patterns in the loch and decreases with increased farm separation. The connectivity indices are used to estimate the origins of the sea lice population composition at each site, which may influence medicinal regimens to avoid loss of efficacy.

Development and assessment of a biophysical dispersal model for sea lice.

Salmon aquaculture in Scotland continues to increase; however, one of the potential limitations to its further sustainable growth is the ectoparasitic sea louse Lepeophtheirus salmonis. The industry in Scotland undertakes coordinated management procedures to control the levels of sea lice on farms in designated production areas. We developed a biophysical sea lice dispersal model for Loch Linnhe, one of the largest fjords on the west coast of Scotland, to provide further information to help establish more effective farm management areas. We successfully extend modelling principles previously applied to a small Scottish fjordic system. Modelling scenarios demonstrate heterogeneity in the distribution of sea lice within the system and simulations, suggesting that lice could be transmitted up to 30 km. The scenarios are assessed by comparing model predictions against lice sampled by both planktonic trawls and settlement on sentinel caged fish. The model predicts the ranked abundance of both planktonic and settled lice assuming that the lice input to the system is relative to host biomass. Data collection is ongoing for undertaking and assessing additional scenarios.

A rapid evidence assessment of the potential risk to the environment presented by active ingredients in the UK's most commonly sold companion animal parasiticides.

A number of parasiticides are commercially available as companion animal treatments to protect against parasite infestation and are sold in large volumes. These treatments are not intended to enter the wider environment but may be washed off or excreted by treated animals and have ecotoxic impacts. A systematic literature review was conducted to identify the existing evidence for the toxicity of the six most used parasiticides in the UK: imidacloprid, fipronil, fluralaner, afoxolaner, selamectin, and flumethrin. A total of 17,207 published articles were screened, with 690 included in the final evidence synthesis. All parasiticides displayed higher toxicity towards invertebrates than vertebrates, enabling their use as companion animal treatments. Extensive evidence exists of ecotoxicity for imidacloprid and fipronil, but this focuses on exposure via agricultural use and is not representative of environmental exposure that results from use in companion animal treatments, especially in urban greenspace. Little to no evidence exists for the ecotoxicity of the remaining parasiticides. Despite heavy usage, there is currently insufficient evidence to understand the environmental risk posed by these veterinary treatments and further studies are urgently needed to quantify the levels and characterise the routes of environmental exposure, as well as identifying any resulting environmental harm.

The Nutritional Profiles of Five Important Edible Insect Species From West Africa-An Analytical and Literature Synthesis.

Background: Undernutrition is a prevalent, serious, and growing concern, particularly in developing countries. Entomophagy-the human consumption of edible insects, is a historical and culturally established practice in many regions. Increasing consumption of nutritious insect meal is a possible combative strategy and can promote sustainable food security. However, the nutritional literature frequently lacks consensus, with interspecific differences in the nutrient content of edible insects generally being poorly resolved. Aims and methods: Here we present full proximate and fatty acid profiles for five edible insect species of socio-economic importance in West Africa: Hermetia illucens (black soldier fly), Musca domestica (house fly), Rhynchophorus phoenicis (African palm weevil), Cirina butyrospermi (shea tree caterpillar), and Macrotermes bellicosus (African termite). These original profiles, which can be used in future research, are combined with literature-derived proximate, fatty acid, and amino acid profiles to analyse interspecific differences in nutrient content. Results: Interspecific differences in ash (minerals), crude protein, and crude fat contents were substantial. Highest ash content was found in H. illucens and M. domestica (~10 and 7.5% of dry matter, respectively), highest crude protein was found in C. butyrospermi and M. domestica (~60% of dry matter), whilst highest crude fat was found in R. phoenicis (~55% of dry matter). The fatty acid profile of H. illucens was differentiated from the other four species, forming its own cluster in a principal component analysis characterized by high saturated fatty acid content. Cirina butyrospermi had by far the highest poly-unsaturated fatty acid content at around 35% of its total fatty acids, with α-linolenic acid particularly represented. Amino acid analyses revealed that all five species sufficiently met human essential amino acid requirements, although C. butyrospermi was slightly limited in leucine and methionine content. Discussion: The nutritional profiles of these five edible insect species compare favorably to beef and can meet human requirements, promoting entomophagy's utility in combatting undernutrition. In particular, C. butyrospermi may provide a source of essential poly-unsaturated fatty acids, bringing many health benefits. This, along with its high protein content, indicates that this species is worthy of more attention in the nutritional literature, which has thus-far been lacking.

Children's surgery cancelled due to malaria and anaemia.

At our hospital 461 children were admitted for elective orthopaedic and reconstructivesurgery between January and December 2003; 90 of these (19.5%) were positive for malaria, and 37 (8%) had haemoglobin levels below 8 g/dL. The mean delay between admission and operation was five days for patients without anaemia or malaria, 7.17 days for patients with malaria,11.05 days for patients with anaemia and 13 days for patients with both anaemia and malaria.

Electrochemical communication with the inside of cells using micro-patterned vertical carbon nanofibre electrodes.

With the rapidly increasing demands for ultrasensitive biodetection, the design and applications of new nano-scale materials for development of sensors based on optical and electrochemical transducers have attracted substantial interest. In particular, given the comparable sizes of nanomaterials and biomolecules, there exist plenty of opportunities to develop functional nanoprobes with biomolecules for highly sensitive and selective biosensing, shedding new light on cellular behaviour. Towards this aim, herein we interface cells with patterned nano-arrays of carbon nanofibers forming a nanosensor-cell construct. We show that such a construct is capable of electrochemically communicating with the intracellular environment.

Conjugated polyelectrolyte nano field emission adlayers.

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum-emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented emitter micro-morphology and shifted surface band structure. The composite emitters can be optically modulated by exploiting the absorption cross-section of the solution cast adlayer, which increases the local carrier concentration which broadens the effective electrostatic shape of the emitter during optical excitation. Assessment via scanning anode field emission microscopy reveals a 25% improvement in DC time stability, a significant reduction in long-term hysteresis shift, and a threefold increase in bandwidth during pulsed mode operation.

Salmonella-induced cell death: apoptosis, necrosis or programmed cell death?

Over the past several years, it has become apparent that enteropathogens activate cell death programs. For Salmonella and Shigella species, the induction of cell death is required for pathogenesis, and the mechanisms by which these bacteria induce cell death is an area of intense investigation. Although initial studies suggested that Salmonella induce cell death through an apoptotic pathway, recent studies demonstrate that cell death occurs through a unique caspase 1-dependent mechanism.

Circular dichroism of diphtheria toxin, Pseudomonas aeruginosa exotoxin A, and various derivatives.

We have recorded the near- and far-ultraviolet circular dichroism spectra of diphtheria toxin, Pseudomonas aeruginosa exotoxin A, and derivatives of these toxins. The far-ultraviolet spectra of various forms of diphtheria toxin were virtually identical, implying that no major changes in secondary structure accompany proteolytic nicking or dimerization of toxin, or binding of the endogenous dinucleotide, adenylyl-(3'-5')-uridine 3'-monophosphate (AdoPUrdP). Alpha-helix content was estimated to be 29%, as compared with 8% for fragment A. Near-ultraviolet spectra were identical between nicked and intact diphtheria toxin. A broad negative transition with a minimum at 304 nm was assigned to the intrachain disulfide bridge within the B moiety. Dimeric diphtheria toxin showed perturbations of aromatic residues. Binding of AdoPUrdP to monomeric diphtheria toxin or of adenylyl-(3',5')-uridine (AdoPUrd) to fragment A perturbed one or more tryptophans. The latter results correlate with evidence for involvement of a tryptophan in NAD binding. Native exotoxin A was estimated to have 16% alpha-helix, and the activated form of exotoxin A, 11%. An enzymically active, 31 kDa proteolytic fragment of exotoxin A showed similar alpha-helix content (7%) to that of diphtheria toxin fragment A.

Right ventricular dysfunction and the exercise limitation of chronic obstructive pulmonary disease.

This study examined right ventricular function during exercise in patients with chronic obstructive pulmonary disease to answer the following questions: Is there a significant correlation between oxygen consumption at maximal exercise and exercise right ventricular ejection fraction? Does the right ventricular ejection fraction response to exercise correlate with exercise changes in pulmonary artery pressure, total pulmonary resistance or pulmonary vascular resistance? Which combinations of cardiac, ventilatory and blood gas variables are the best predictors of oxygen consumption at maximal exercise? Twenty-six patients with stable chronic obstructive pulmonary disease performed symptom-limited supine bicycle exercise with simultaneous hemodynamic and radionuclide ventriculographic measurements. The oxygen consumption at maximal exercise correlated with the exercise right ventricular ejection fraction (n = 21, r = 0.66; p less than 0.005), exercise stroke volume (r = 0.68; p less than 0.001), exercise cardiac output (r = 0.77; p less than 0.00005) and exercise ventilation (r = 0.85; p less than 0.00001). The change in right ventricular ejection fraction from rest to exercise correlated inversely with the change from rest to exercise in total pulmonary resistance (r = -0.51; p less than 0.05) but not with the change in mean pulmonary pressure (r = -0.37) or in pulmonary vascular resistance (r = 0.09). Multivariate analysis showed that the variables giving the highest combined correlation with oxygen consumption were ventilation and right ventricular ejection fraction (r = 0.95, adjusted r2 = 0.88). These results suggest that exercise oxygen consumption of patients with chronic obstructive pulmonary disease is related to right ventricular systolic function, exercise right ventricular dysfunction is related, in part, to abnormal exercise total pulmonary resistance, and exercise limitation in chronic obstructive pulmonary disease occurs as a result of the dynamic interaction between disordered right heart function and ventilation.

Regional activation in the rat brain during visceral stimulation detected by c-fos expression and fMRI.

AIM: The aim of the study was to determine and compare the areas of brain activated in response to colorectal distention (CRD) using functional magnetic resonance imaging (fMRI) and c-fos protein expression. METHODS: For fMRI study (3.0 T magnet), anaesthetized rats underwent phasic CRD, synchronized with fMRI acquisition. Stimulation consisted of eight cycles of balloon deflation (90 s) and inflation (30 s), at 40, 60 or 80 mmHg of pressure. For c-fos study two sets of experiments were performed on anaesthetized rats: comparing (A) brain activation in rats with the inserted colorectal balloon (n = 5), to the rats without the balloon (n = 5); and (B) rats with inserted balloon (n = 10), to the rats with inserted and distended balloon (n = 10). The pressure of 80 mmHg was applied for 2 h of 30 s inflation and 90 s deflation, alternating cycles. RESULTS: Functional MRI revealed significant activation in the amygdala, hypothalamus, thalamus, cerebellum and hippocampus. Significant increase in c-fos expression was observed in amygdala and thalamus in the first set of experiments, and hypothalamus and parabrachial nuclei in the second. CONCLUSION: The two methods are not interchangeable but appeared to be complementary: fMRI was more sensitive, whereas c-fos had much greater resolution.

Adaptive Real-Time Closed-Loop Temperature Control for Ultrasound Hyperthermia Using Magnetic Resonance Thermometry.

Previous researchers have successfully demonstrated the application of temperature feedback control for thermal treatment of disease using MR thermometry. Using the temperature-dependent proton resonance frequency (PRF) shift, ultrasound heating for hyperthermia to a target organ (such as the prostate) can be tightly controlled. However, using fixed gain controllers, the response of the target to ultrasound heating varies with type, size, location, shape, stage of growth, and proximity to other vulnerable organs. To adjust for clinical variables, feedback self-tuning regulator (STR) and model reference adaptive control (MRAC) methods have been designed and implemented using real-time, online MR thermometry by adjusting the output power to an ultrasound array to quickly reach the hyperthermia target temperatures. The use of fast adaptive controllers in this application is advantageous because adaptive controllers do not require a priori knowledge of the initial tissue properties and blood perfusion and can quickly reach the steady-state target temperature in the presence of dynamic tissue properties (e.g., thermal conductivity, blood perfusion). This research was conducted to rapidly achieve and manage therapeutic temperatures from an ultrasound array using novel MRI-guided adaptive closed-loop controllers both in ex vivo and in vivo experiments. The ex vivo phantom experiments with bovine muscle (n = 5) show that within 6 ± 0.2 minutes, the tissue temperature increased by 8 ± 1.37°C. Using rabbits' (n = 5) thigh muscle, the in vivo experiments demonstrated the target temperature reached 44.5°C ± 1.2°C in 8.0 ± 0.5 minutes. The preliminary in vivo experiment with canine prostate hyperthermia achieved 43 ± 2°C in 6.5 ± 0.5 minutes. These results demonstrate that the adaptive controllers with MR thermometry are able to effectively track the target temperature with dynamic tissue properties.

Calculations of B1 Distribution, Specific Energy Absorption Rate, and Intrinsic Signal-to-Noise Ratio for a Body-Size Birdcage Coil Loaded with Different Human Subjects at 64 and 128 MHz.

A numerical model of a female body is developed to study the effects of different body types with different coil drive methods on radio-frequency magnetic (B1) field distribution, specific energy absorption rate (SAR), and intrinsic signal-to-noise ratio (ISNR) for a body-size birdcage coil at 64 and 128 MHz. The coil is loaded with either a larger, more muscular male body model (subject 1) or a newly developed female body model (subject 2), and driven with two-port (quadrature), four-port, or many (ideal) sources. Loading the coil with subject 1 results in significantly less homogeneous B1 field, higher SAR, and lower ISNR than those for subject 2 at both frequencies. This dependence of MR performance and safety measures on body type indicates a need for a variety of numerical models representative of a diverse population for future calculations. The different drive methods result in similar B1 field patterns, SAR, and ISNR in all cases.

Structural features of a zinc binding site in the superantigen strepococcal pyrogenic exotoxin A (SpeA1): implications for MHC class II recognition.

Streptococcal pyrogenic exotoxin A (SpeA) is produced by Streptococcus pyogenes, and has been associated with severe infections such as scarlet fever and Streptococcal Toxic Shock Syndrome (STSS). In this study, the crystal structure of SpeA1 (the product of speA allele 1) in the presence of 2.5 mM zinc was determined at 2.8 A resolution. The protein crystallizes in the orthorhombic space group P2(1)2(1)2, with four molecules in the crystallographic asymmetric unit. The final structure has a crystallographic R-factor of 21.4% for 7,031 protein atoms, 143 water molecules, and 4 zinc atoms (one zinc atom per molecule). Four protein ligands-Glu 33, Asp 77, His 106, and His 110-form a zinc binding site that is similar to the one observed in a related superantigen, staphylococcoal enterotoxin C2. Mutant toxin forms substituting Ala for each of the zinc binding residues were generated. The affinity of these mutants for zinc ion confirms the composition of this metal binding site. The implications of zinc binding to SpeA1 for MHC class II recognition are explored using a molecular modeling approach. The results indicate that, despite their common overall architecture, superantigens appear to have multiple ways of complex formation with MHC class II molecules.

Structural similarities and differences in Staphylococcus aureus exfoliative toxins A and B as revealed by their crystal structures.

Staphylococcal aureus epidermolytic toxins (ETs) A and B are responsible for the induction of staphylococcal scalded skin syndrome, a disease of neonates and young children. The clinical features of this syndrome vary from localized blisters to severe exfoliation affecting most of the body surface. Comparison of the crystal structures of two subtypes of ETs-rETA (at 2.0 A resolution), rETB (at 2.8 A resolution), and an active site variant of rETA, Ser195Ala at 2.0 A resolution has demonstrated that their overall topology resembles that of a "trypsin-like" serine protease, but with significant differences at the N- and C-termini and loop regions. The details of the catalytic site in both ET structures are very similar to those in glutamate-specific serine proteases, suggesting a common catalytic mechanism. However, the "oxyanion hole," which is part of the catalytic sites of glutamate specific serine proteases, is in the closed or inactive conformation for rETA, yet in the open or active conformation for rETB. The ETs contain a unique amphipathic helix at the N-terminus, and it appears to be involved in optimizing the conformation of the catalytic site residues. Determination of the structure of the rETA catalytic site variant, Ser195Ala, showed no significant perturbation at the active site, establishing that the loss of biological and esterolytic activity can be attributed solely to disruption of the catalytic serine residue. Finally, the crystal structure of ETs, together with biochemical data and mutagenesis studies, strongly confirms the classification of these molecules as "serine proteases" rather than "superantigens."

Molecular basis of group A streptococcal virulence.

The group A streptococcus (GAS) (Streptococcus pyogenes) is among the most common and versatile of human pathogens. It is responsible for a wide spectrum of human diseases, ranging from trivial to lethal. The advent of modern techniques of molecular biology has taught much about the organism's virulence, and the genomes of several GAS types have now been deciphered. Surface structures of GAS including a family of M proteins, the hyaluronic acid capsule, and fibronectin-binding proteins, allow the organism to adhere to, colonise, and invade human skin and mucus membranes under varying environmental conditions. M protein binds to complement control factors and other host proteins to prevent activation of the alternate complement pathway and thus evade phagocytosis and killing by polymorphonuclear leucocytes. Extracellular toxins, including superantigenic streptococcal pyrogenic exotoxins, contribute to tissue invasion and initiate the cytokine storm felt responsible for illnesses such as necrotising fasciitis and the highly lethal streptococcal toxic shock syndrome. Progress has been made in understanding the molecular epidemiology of acute rheumatic fever but less is understood about its basic pathogenesis. The improved understanding of GAS genetic regulation, structure, and function has opened exciting possibilities for developing safe and effective GAS vaccines. Studies directed towards achieving this long-sought goal are being aggressively pursued.

Expression of major histocompatibility complex (MHC) antigens and their loss on culture in renal carcinoma.

Biopsies from the tumour and the adjacent normal kidney were obtained from 15 patients with renal cell carcinoma (RCC). The proximal convoluted tubules from which the tumour arose expressed major histocompatibility complex (MHC) class I antigen (Ag) in 3 cases and class II in none. By contrast, the carcinoma cells expressed class I Ag in 14 cases and class II Ag in 5 cases. Cells from each carcinoma were established in culture. As the culture period increased, cells from six of eight RCC showed diminished expression of class I Ag and five of six reduced expression of class II Ag. This is similar to the relative loss of class I Ag in synchronous metastases from RCC.