Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only

The objective of our study was to assess the long-term outcome of patients with prosthetic valve endocarditis. We used a multicenter, prospective, observational study design. Six university teaching hospitals with high volume cardiothoracic surgery participated. Seventy-four patients with prosthetic valve endocarditis as defined by explicit, objective criteria were selected for participation. All patients were followed up prospectively for 1 year. Thirty-one percent and 69% had development of endocarditis within 60 days of valve insertion ("early") and after 60 days ("late"), respectively. The most common causes were Staphylococcus epidermidis (40%), Staphylococcus aureus (20%), streptococcal species (18%), and aerobic gram-negative bacilli (11%). Physical signs of endocarditis (new or changing murmur, stigmata, emboli) were seen in 58%. At 6 months and 12 months, mortality was 46% and 47%, respectively. Surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%), as assessed by both univariate and multivariate analyses (p < 0.05). Improved outcome was seen for the surgical group even when controlling for severity of illness at time of diagnosis. From these findings we conclude that accurate assessment of outcome in prosthetic valve endocarditis requires long-term follow-up of at least 6 months following diagnosis. Surgical therapy warrants greater scrutiny; evaluation in controlled clinical trials is appropriate.     

Packing products for customers: an ergonomics evaluation of three supermarket checkouts

The introduction of laser scanners at supermarket checkout areas has resulted in previous ergonomics studies focusing specifically on the scanning process and associated cumulative trauma disorders in the hands and arms. Few studies have evaluated the increased musculoskeletal load and exertion of checkout staff when they are also expected to pack the products into bags for the customers. This paper describes an ergonomics evaluation of three different designs of checkout workstation, which require the operator to stand when they scan the products, pack them into plastic bags and transfer the packed bags to the customer. Musculoskeletal load and exertion associated with the different checkouts were measured using OWAS, heart rate recordings and ratings of perceived exertion. In addition, subjective rankings of the workstations were obtained and the productivity associated with each design examined as part of the evaluation. Some of the variables measured showed significant differences in postural load between the workstations. The results of the evaluation formed the basis of recommendations for an improved workstation design. Some of the suggestions made to reduce postural load and increase productivity include positioning the weigh scale to the side and the bag frame beneath the scanner.     

The mitochondrial genome integrity gene, MGI1, of Kluyveromyces lactis encodes the beta-subunit of F1-ATPase

In a previous report, we found that mutations at the mitochondrial genome integrity locus, MGI1, can convert Kluyveromyces lactis into a petite-positive yeast. In this report, we describe the isolation of the MGI1 gene and show that it encodes the beta-subunit of the mitochondrial F1-ATPase. The site of mutation in four independently isolated mgi1 alleles is at Arg435, which has changed to Gly in three cases and Ile in the fourth isolate. Disruption of MGI1 does not lead to the production of mitochondrial genome deletion mutants, indicating that an assembled F1 complex is needed for the "gain-of-function" phenotype found in mgi1 point mutants. The location of Arg435 in the beta-subunit, as deduced from the three-dimensional structure of the bovine F1-ATPase, together with mutational sites in the previously identified mgi2 and mgi5 alleles, suggests that interaction of the beta- and alpha- (MGI2) subunits with the gamma-subunit (MGI5) is likely to be affected by the mutations.     

Fast transmission CT for determining attenuation maps using a collimated line source, rotatable air-copper-lead attenuators and fan-beam collimation

We describe a technique using a line source and a rotatable air-copper-lead assembly to acquire gamma transmission computed tomographic (TCT) data for determining attenuation maps to compensate SPECT emission scans. The technique minimizes problems associated with discriminating 99mTc transmission and 201Tl emission photons and requires only a modest increase in total study time. A 99mTc line source and a stacked foil ("multislat") collimator are placed near the focal line of a fan-beam collimator (114 cm focal length) mounted on one detector of a triple-camera SPECT system. We acquired TCT data of plastic rod and anthropomorphic thorax phantoms to investigate the capability of the line source and rotatable air-copper-lead attenuators to determine attenuation maps. The data were acquired with and without 5.4 MBq (145 microCi) of 201Tl placed in the myocardial chamber of the thorax phantom. Phantoms also were scanned using a curved transmission slab source mounted to a parallel-hole collimator. Fan-beam TCT images have improved resolution compared with parallel-beam TCT images. Two patient scans also were performed to evaluate the clinical usefulness of fan-beam TCT. The rotatable air-copper-lead attenuator method eliminates contamination of emission data by transmission photons and reduces spill-over of emission data into the transmission energy window for some cases. Results show the feasibility of using fast, sequential or interlaced transmission scans of a line source within a rotatable air-copper-lead attenuator assembly to obtain accurate attenuation maps for SPECT attenuation compensation.     

A demographic overview of the ageing of First World populations

The ageing of the UK population, and other similar populations, is now well advanced. The process is probably irreversible and may well be repeated across the globe. It is reasonable to assume that 40-50% of the UK adult population will be over 50 for the foreseeable future, and that the number of people in their 80s and 90s will continue to increase for some decades. Growing awareness of this may well lead to a reinterpretation of the life course with consequent changes in lifestyle and activity. In the past, the main focus of design, both of products and environments, has been the working population. There is clearly an urgent need to direct attention to older sectors of the population, including: fit and active people in retirement; affluent groups in old age; single households; women, who form a majority of the over 50s; and other groups which have been neglected in many work studies.     

Uncouplers can shuttle between localized energy-coupling sites during photophosphorylation by chromatophores of Rhodopseudomonas capsulata N22

Two models of the action of uncoupler molecules in inhibiting photophosphorylation in bacterial chromatophores are considered: either uncoupler molecules shuttle rapidly between energy-coupling sites, or uncoupler molecules that are bound to particular sites in the chromatophores for a time that is comparable with the turnover time of the photophosphorylation apparatus may uncouple by a co-operative "substoichiometric' mechanism. It is found that the titre of uncoupler necessary to cause complete uncoupling is lowered if the rate of photophosphorylation is initially decreased by partially restricting electron flow with an appropriate titre of antimycin A. This result indicates that uncoupler molecules shuttle rapidly between energy coupling in which the energized intermediate between electron transport and phosphorylation is delocalized over the entire chromatophore membrane and those in which it is not. If the rate of photophosphorylation is partially restricted with the covalent H+-translocating ATP synthase inhibitor dicyclohexylcarbodi-imide, the titre of uncoupler necessary to effect complete inhibition of photophosphorylation is also decreased relative to that in which the covalent H+-ATP synthase inhibitor is absent. This important result appears to be inconsistent with models of electron-transport phosphorylation in which the "energized state' of the chromatophore membrane that is set up by electron transport and utilized in photophosphorylation is delocalized over the entire chromatophore membrane.     

Development and use of a two-dimensional interferometer to measure mass flow from a multi-shell Z-pinch gas puff

For gas puff Z-pinches, the K-shell x-ray yield is maximized with the use of a multi-shell nozzle. Optimization of the yield, verification of hydrodynamic models of the nozzle flows, and plausible MHD code modeling of the implosions require data on the radial and axial (R,Z) distribution of mass in the nozzle's flow field. Interferometry is a well-established technique for acquiring such data. We describe the development and use of a two-dimensional interferometer with emphasis on the required data reduction methods. We also show that the instrument can derive the flow from each individual nozzle in a multi-shell system.     

Development of environmentally responsive hydrogels with metal affinity behavior

This work describes initial efforts to incorporate affinity ligands within an environmentally responsive hydrogel. Metal affinity ligands were chosen as model affinity groups and thermally responsive N‐isopropyl acrylamide/acrylamide copolymers were used as the base hydrogels. The ? NH₂ group of the acrylamide serves as a reactive group for functionalization with metal affinity ligands. The gels were synthesized by free radical polymerization and Cu²⁺ was bound to the gel via 1,4‐butanediol diglycidyl ether (BDE) as a linker and iminodiacetic acid (IDA) as a chelating ligand. The base acrylamide gels were also functionalized with metal affinity ligands to allow for comparison with thermally responsive affinity gels. The results show the effectiveness of this technique for both these types of gels, and an improved method to immobilize metal affinity groups on to thermally sensitive N‐isopropyl acrylamide gels was also developed. It was seen that the yields for the reaction with BDE decreased with increased reaction time in both kinds of gels, whereas reaction with IDA showed a decrease in yields with increase in temperature for N‐isoporpyl acrylamide gels and increase in yields for acrylamide gels. Further techniques were developed to overcome diffusional resistances and stresses in the thermally responsive N‐isopropyl acrylamide gels so as to improve the distribution of Cu²⁺ ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

High-power high-Modulation-speed 1060-nm DBR lasers for Green-light emission

We report on the static and dynamic performance of high-power and high-modulation-speed 1060-nm distributed Bragg reflector (DBR) lasers for green-light emission by second-harmonic generation. Single-wavelength power of 387 mW at 1060-nm wavelength and green power as high as 99.5 mW were achieved. A thermally induced wavelength tuning of 2.4 nm and a carrier-induced wavelength tuning of -0.85 nm were obtained by injecting current into the DBR section. Measured rise-fall times of 0.2 ns for direct intensity modulation and 0.6 ns for wavelength modulation make the lasers suitable for >50-MHz green-light modulation applications.