Imaging of Titan from the Cassini spacecraft.

Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of these issues. The images reveal intricate surface albedo features that suggest aeolian, tectonic and fluvial processes; they also show a few circular features that could be impact structures. These observations imply that substantial surface modification has occurred over Titan's history. We have not directly detected liquids on the surface to date. Convective clouds are found to be common near the south pole, and the motion of mid-latitude clouds consistently indicates eastward winds, from which we infer that the troposphere is rotating faster than the surface. A detached haze at an altitude of 500 km is 150-200 km higher than that observed by Voyager, and more tenuous haze layers are also resolved.

A novel rapid and effective donor arm disinfection method.

BACKGROUND: The aim of the study was to derive a donor arm disinfection technique that was rapid, but with a disinfection efficacy equivalent to a previous "best-practice" technique. This method consisted of a two-stage procedure with an initial application of 70% isopropyl alcohol and then 2% tincture of iodine (IATI). The total time for the IATI method was 2 minutes in duration. A rapid technique (1 min in duration) was needed to obviate potential problems due to increased donor waiting time, had the IATI method been implemented at blood donation sessions. STUDY DESIGN AND METHODS: A direct swabbing and plating technique was used to enumerate bacteria present before and after disinfection. In total, seven methods were evaluated. RESULTS: The chlorhexidine/alcohol applicator (CAA) disinfection device containing 1.5 mL of 2% chlorhexidine gluconate and 70% isopropyl alcohol (99.91% reduction; confidence limits, 99.55%, 99.98%) was shown to have equivalent disinfection efficacy as the IATI method (99.89% reduction; confidence limits, 99.36%, 99.98%; p = 0.86). Procedural time for the 1.5-mL CAA method was 1 minute thereby avoiding potential problems of increased donor waiting time, inherent in the IATI 2-minute procedure at blood donation sessions. CONCLUSIONS: The 1.5-mL CAA disinfection method offers blood services a rapid and effective donor arm disinfection procedure. In 2006, the 1.5-mL CAA procedure was implemented throughout the entire English blood service for all donations.

The National Blood Service (England) approach to evaluation of kits for detecting infectious agents.

Blood services test their donations for a range of infectious agents before release for transfusion. To ensure that the assays used have appropriate sensitivity, subtype detection range, and specificity, and meet operational requirements (timeliness, automation, and process control), some form of selection is needed. The approach of the English National Blood Service (NBS) to the evaluation of commercial kits to assess their suitability is presented. As a centrally coordinated national service the NBS has the "critical mass" and can generate the economies of scale, to support a national kit evaluation group (KEG). Because England is within the European Union, KEG has no "licensing" function for manufacturers' kits which must be "Communautés Européennes marked" before they can be sold within the Union. The European Union's in vitro diagnostics directive sets out common technical specifications which manufacturers must meet. There are also UK ethical constraints on the use of patient/donor blood or tissue samples which must be complied with. In this context, KEG assesses the specificity of assays in collaboration with the blood center donation testing departments. The sensitivity of assays is determined in collaboration with the Health Protection Agency and the NBS National Transfusion Microbiology Reference Laboratory using performance panels, seroconversion panels, and a large range of divergent strains to assess detection range.

Risks and side effects of therapy with plasma and plasma fractions.

Transfusion of plasma can lead to adverse reactions or events. Immune-mediated reactions are most common--these include allergic and anaphylactic reactions, transfusion-related acute lung injury (TRALI) and haemolysis. They can range in severity from mild to fatal. Fluid overload and citrate toxicity can occur after rapid or massive transfusion. In developed countries, microbial transmission rates are low because of donor selection and testing. Pathogen reduction processes can be applied to either single-unit components (methylene blue) or plasma pools (solvent-detergent). They have the unwanted effect of reducing some coagulation factors but reduce viral transmission risk even further. Reactions associated with plasma products or fractions also include allergic reactions, although TRALI is rare. Viral transmission risk is very low because of the use of two independent viral inactivation steps. Different products have particular specific unwanted effects: intravenous immunoglobulin has been associated with thrombotic events, renal toxicity and aseptic meningitis; coagulation factors are associated with development of inhibitors and thrombotic events. The risk of transmission of variant Creutzfeldt-Jakob disease in both plasma components and pooled plasma products is as yet unknown. If anything, the low titre of prion infectivity in the blood of an infected individual (approximately 10 infectious units/ml) will be massively diluted by the thousands of units of plasma in the pool. Subsequent manufacturing processes also remove prions from the final product.

The rationale for pathogen-inactivation treatment of blood components.

Blood transfusion provides an ideal portal of entry for microorganisms. Although current residual risks of microbial infection by transfusion are extremely low in the developed world, the requirements for even safer blood are paradoxically increasing. Such requirements are partly a legacy of the tragic transmissions of human immunodeficiency virus (HIV) by blood early in the acquired immunodeficiency syndrome pandemic and are legally expressed in consumer protection laws imposing strict product liability. Enhanced safety is called for, not only for recognized agents (especially bacteria, which cause most current transfusion-transmissible infections [TTIs]and have only recently been addressed) but also for potential future "emerging" TTIs. These possibilities are not merely theoretical. TTIs of HIV-1, HIV-2, hepatitis B virus vaccine escape mutants, human herpesvirus 8, West Nile fever virus, and variant Creutzfeld-Jakob disease amply demonstrate the continual emergence of such threats. For recognized agents, the possibilities of test errors, misreporting, process-control failures, and false-negative results (although rare with modern automation) remain. In principle, an all-embracing, pan-effective microbe-inactivation procedure offers a potential solution to blood safety concerns. Such procedures may also allow the removal of several existing antimicrobial interventions. However, blood services remain to be convinced that the various prerequisites for safe and effective pathogen inactivation have been met. Not the least of these prerequisites is that all blood components can be inactivated to provide a single streamlined alternative blood safety strategy. Furthermore, the huge potential value of effective pathogen-inactivation systems for developing countries should not be forgotten once such systems are perfected.

Dynamics of Saturn's south polar vortex.

The camera onboard the Cassini spacecraft has allowed us to observe many of Saturn's cloud features. We present observations of Saturn's south polar vortex (SPV) showing that it shares some properties with terrestrial hurricanes: cyclonic circulation, warm central region (the eye) surrounded by a ring of high clouds (the eye wall), and convective clouds outside the eye. The polar location and the absence of an ocean are major differences. It also shares properties with the polar vortices on Venus, such as polar location, cyclonic circulation, warm center, and long lifetime, but the Venus vortices have cold collars and are not associated with convective clouds. The SPV's combination of properties is unique among vortices in the solar system.

A 5-micron-bright spot on Titan: evidence for surface diversity.

Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80 degrees W and 20 degrees S. This area is bright in reflected light at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Science Subsystem. We discuss various hypotheses about the source of the spot, reaching the conclusion that the spot is probably due to variation in surface composition, perhaps associated with recent geophysical phenomena.

Evaluation of a transcription-mediated amplification-based HCV and HIV-1 RNA duplex assay for screening individual blood donations: a comparison with a minipool testing system.

BACKGROUND: NAT was introduced for HCV RNA in 1999 to screen blood donations and improve the safety of the blood supply. STUDY DESIGN AND METHODS: The performance of a NAT multiplex for HCV and HIV-1 RNA based on transcription-mediated amplification (TMA) was assessed with various sensitivity panels and by screening 50,000 serologically unscreened, first-time donor plasma samples. Results were compared with a routine NAT screening for HCV RNA by RT-PCR in pools of 96 plasma samples. RESULTS: The TMA multiplex 95 percent sensitivity ranged between 22 and 54 IU per mL for HIV-1 and 15 and 20 IU per mL for HCV RNA. The rate of test failure was 8.6 percent but decreased to 4.7 percent when results of two critical periods of equipment malfunction were excluded. Test failure was related to human error, minute control contamination, and insufficient mixing of reagents at the extraction stage. All 31 repeatedly reactive samples (0.06%) were seropositive for HCV (29) or HIV-1 (2) and contained RNA detectable by discriminatory TMA and confirmatory RT-PCR, indicating 100 percent specificity. A direct comparison of TMA in individual samples and RT-PCR in plasma pools was possible on 27 HCV RNA-containing samples. Twenty-six samples were detected in plasma pools; the lack of detection of 1 sample was due to an identification error at the pooling stage. CONCLUSION: The HCV and HIV-1 multiplex NAT had high specificity and sensitivity.

Evidence for a dynamic host-parasite relationship in e-negative hepatitis B carriers.

Anti-hepatitis Be (HBe) carriers are perceived as having low infectivity, with hepatitis B virus (HBV) DNA levels far below those seen in the HBeAg carrier. However, the temporal stability of HBV DNA in anti-HBe carriers remains poorly characterised. UK Department of Health guidelines use HBV DNA levels to define whether HBV-infected health care workers may perform exposure-prone procedures. Two samples separated by 1-23 years available from 147 carriers were analysed for precore variants and HBV DNA levels. Among 15 HBeAg carriers, HBV DNA was maintained at high levels. There was a 5 log(10) fold reduction in DNA in 11 individuals who developed anti-HBe during follow-up evaluation. Proportional changes in HBV DNA levels in anti-HBe carriers were similar to those in HBeAg carriers, although there was a trend for changes in viral DNA to be more marked in anti-HBe carriers followed up for longer periods. Closer sampling in 20 anti-HBe carriers demonstrated large fluctuations of DNA levels over short periods. Serum transaminases and precore mutant status at the outset failed to predict those in whom HBV DNA levels fluctuated. HBV DNA was below the detection threshold (<400 copies/ml) in 36 anti-HBe carriers at first sampling and remained so in all but 5 of these carriers. Twelve individuals who were previously viraemic lost detectable HBV DNA during follow-up evaluation. While HBV DNA levels are found to fluctuate in carriers, our results indicate that once below the threshold of detectability, levels are unlikely to rise. This is an important factor when assessing health care workers for exposure-prone procedures.

Cassini imaging of Jupiter's atmosphere, satellites, and rings.

The Cassini Imaging Science Subsystem acquired about 26,000 images of the Jupiter system as the spacecraft encountered the giant planet en route to Saturn. We report findings on Jupiter's zonal winds, convective storms, low-latitude upper troposphere, polar stratosphere, and northern aurora. We also describe previously unseen emissions arising from Io and Europa in eclipse, a giant volcanic plume over Io's north pole, disk-resolved images of the satellite Himalia, circumstantial evidence for a causal relation between the satellites Metis and Adrastea and the main jovian ring, and information on the nature of the ring particles.