A High-Sensitivity Benchtop X-Ray Fluorescence Emission Tomography (XFET) System With a Full-Ring of X-Ray Imaging-Spectrometers and a Compound-Eye Collimation Aperture

The advent of metal-based drugs and metal nanoparticles as therapeutic agents in anti-tumor treatment has motivated the advancement of X-ray fluorescence computed tomography (XFCT) techniques. An XFCT imaging modality can detect, quantify, and image the biodistribution of metal elements using the X-ray fluorescence signal emitted upon X-ray irradiation. However, the majority of XFCT imaging systems and instrumentation developed so far rely on a single or a small number of detectors. This work introduces the first full-ring benchtop X-ray fluorescence emission tomography (XFET) system equipped with 24 solid-state detectors arranged in a hexagonal geometry and a 96-pinhole compound-eye collimator. We experimentally demonstrate the system's sensitivity and its capability of multi-element detection and quantification by performing imaging studies on an animal-sized phantom. In our preliminary studies, the phantom was irradiated with a pencil beam of X-rays produced using a low-powered polychromatic X-ray source (90kVp and 60W max power). This investigation shows a significant enhancement in the detection limit of gadolinium to as low as 0.1 mg/mL concentration. The results also illustrate the unique capabilities of the XFET system to simultaneously determine the spatial distribution and accurately quantify the concentrations of multiple metal elements.

Hybrid energy and angle dispersive X-ray diffraction computed tomography

Pixelated energy resolving detectors enable acquisition of X-ray diffraction (XRD) signals using a hybrid energy- and angle- dispersive technique, potentially paving the way for the development of novel benchtop XRD imaging or computed tomography (XRDCT) systems, utilising readily available polychromatic X-ray sources. In this work, a commercially available pixelated cadmium telluride (CdTe) detector, HEXITEC (High Energy X-ray Imaging Technology), was used to demonstrate such an XRDCT system. Specifically, a novel fly-scan technique was developed and compared to the established step-scan technique, reducing the total scan time by 42% while improving the spatial resolution, material contrast and therefore the material classification.

Resident Wilderness Medicine Curriculum Consensus Guidelines: Summarization and Recommendations for Resident Rotations in Wilderness Medicine

INTRODUCTION

Wilderness medicine education is one of the fastest growing facets of both graduate and undergraduate medical education. Currently, there are curriculum guidelines for both student electives and fellowships in wilderness medicine. However, there are no guidelines for resident elective curricula. The student/resident education committee of the Wilderness Medical Society (WMS) convened a task force to develop curriculum guidelines for these electives.

METHODS

A survey of previously described core wilderness medicine topics was sent to a cohort of educators involved in wilderness medicine resident electives. They were asked to rank topics on the basis of their importance of being included on a Likert scale. Multivariate analysis of medians was used to distinguish among topics to determine which topics were voted most and least necessary for a curriculum.

RESULTS

Of the database members contacted, 35 responded to the survey. The described current state of residency electives was that 16 institutions offered their own elective (46%). For subject preferences, multivariate analysis of scoring distribution medians demonstrated a significantly higher pattern of responses (P<0.01) for subjects with a median of 3 (must include) than for the lowest-scoring subjects that had a median of 1 (can include). Every topic was rated "must" by at least 1 respondent. Topics were further subdivided into an educational framework reflecting a common approach to education of wilderness medicine fellows focusing on education, leadership, knowledge, and skills.

CONCLUSIONS

There was a wide variety in the ranking of topics; however, there were multiple topics on which a consensus for inclusion was reached. These topics are organized and presented here as a suggested curriculum by the student/resident education committee of the WMS.

3D Correlative Imaging of Lithium Ion Concentration in a Vertically Oriented Electrode Microstructure with a Density Gradient

The performance of Li⁺ ion batteries (LIBs) is hindered by steep Li⁺ ion concentration gradients in the electrodes. Although thick electrodes (≥300 µm) have the potential for reducing the proportion of inactive components inside LIBs and increasing battery energy density, the Li⁺ ion concentration gradient problem is exacerbated. Most understanding of Li⁺ ion diffusion in the electrodes is based on computational modeling because of the low atomic number (Z) of Li. There are few experimental methods to visualize Li⁺ ion concentration distribution of the electrode within a battery of typical configurations, for example, coin cells with stainless steel casing. Here, for the first time, an interrupted in situ correlative imaging technique is developed, combining novel, full-field X-ray Compton scattering imaging with X-ray computed tomography that allows 3D pixel-by-pixel mapping of both Li⁺ stoichiometry and electrode microstructure of a LiNi_0.8 Mn_0.1 Co_0.1 O₂ cathode to correlate the chemical and physical properties of the electrode inside a working coin cell battery. An electrode microstructure containing vertically oriented pore arrays and a density gradient is fabricated. It is shown how the designed electrode microstructure improves Li⁺ ion diffusivity, homogenizes Li⁺ ion concentration through the ultra-thick electrode (1 mm), and improves utilization of electrode active materials.

Medullary Screw Fixation and the Pilot Hole Technique for the Correction of Hammertoe Deformity

BACKGROUND

Historically, Kirschner wires have been used for fixation of the interphalangeal joints of the toe. They are still the most popular form of fixation, likely due to training patterns, ease of use, and decreased cost. Recently, numerous medullary fixation devices have become available, including medullary screws.

METHODS

After performing various forms of fixation for the correction of toe deformities, the authors have developed a new pilot hole technique for screw fixation advancing on the previously described pilot hole technique for Kirschner wire fixation.

RESULTS

The authors have found this method to provide intraoperative confidence that improper hardware placement has not occurred.

CONCLUSIONS

The pilot hole technique described in this paper is a safe and effective technique that may be employed by surgeons using screw fixation for the treatment of hammertoe deformities. The technique reduces the possibility of surgeon error and helps to ensure that the screw is properly placed within the phalanges when properly employed.

Outcomes of Ankle Arthrodesis Conversion to Total Ankle Arthroplasty: A Systematic Review

Ankle arthrodesis (AA) provides reliable pain relief, good patient satisfaction scores, and improved overall function. However, this procedure has been associated with numerous complications and sequelae, such as pseudoarthrosis, malunion, gait abnormalities, increased demand on surrounding joints, and a long period of convalescence. Conversion to total ankle arthroplasty (TAA) is a potential option in the management of these complex and challenging situations. The purpose of this study is to investigate the outcomes of AA conversion to TAA. A systematic review of electronic databases was performed. Six studies involving 172 ankles met inclusion criteria. The weighted mean preoperative Visual Analogue Scale (VAS) score at the time of TAA conversion was 7.8 and the weighted mean postoperative VAS score at the time of final follow-up was 2.5. The weighted mean preoperative AOFAS score at the time of TAA conversion was 32 and the weighted mean postoperative AOFAS score at the time of final follow-up was 72.4. The rate of salvage tibiotalocalcaneal arthrodesis was 2.3% and rate of transtibial amputation was also 2.3% after attempted conversion from initial AA to TAA. Conversion of AA to TAA appears to be a viable option to improve patient outcomes and prevent extensive hindfoot arthrodesis and transtibial amputation. More prospective studies with consistent reporting of outcomes, complications, and revision rates with long-term follow-up are needed.

An operando spatially resolved study of alkaline battery discharge using a novel hyperspectral detector and X-ray tomography

An experimental setup is described that uses a hyperspectral imaging detector to collect time-resolved X-ray diffraction information from a complete discharging AA size battery, using a commercial alkaline Zn–Mn cell as a proof of concept. The work is complemented by time-resolved in situ X-ray computed tomography of an identical battery cell.

An experimental technique is described for the collection of time-resolved X-ray diffraction information from a complete commercial battery cell during discharging or charging cycles. The technique uses an 80 × 80 pixel 2D energy-discriminating detector in a pinhole camera geometry which can be used with a polychromatic X-ray source. The concept was proved in a synchrotron X-ray study of commercial alkaline Zn–MnO₂ AA size cells. Importantly, no modification of the cell was required. The technique enabled spatial and temporal changes to be observed with a time resolution of 20 min (5 min of data collection with a 15 min wait between scans). Chemical changes in the cell determined from diffraction information were correlated with complementary X-ray tomography scans performed on similar cells from the same batch. The clearest results were for the spatial and temporal changes in the Zn anode. Spatially, there was a sequential transformation of Zn to ZnO in the direction from the separator towards the current collector. Temporally, it was possible to track the transformation of Zn to ZnO during the discharge and follow the corresponding changes in the cathode.

Development of a multi-detector readout circuitry for ultrahigh energy resolution single-photon imaging applications

In this paper, we present the design and preliminary performance evaluation of a novel external multi-channel readout circuitry for small-pixel room-temperature semiconductor detectors, namely CdZnTe (CZT) and CdTe, that provide an excellent intrinsic spatial (250 and 500 μm pixel size) and an ultrahigh energy resolution (~1% at 122 keV) for X-ray and gamma-ray imaging applications. An analog front-end printed circuit board (PCB) was designed and developed for data digitization, data transfer and ASIC control of pixelated CZT or CdTe detectors. Each detector unit is 2 cm × 2 cm in size and 1 or 2 mm in thickness, being bump-bonded onto a HEXITEC ASIC, and wire-bonded to a readout detector module PCB. The detectors' front-end is then connected, through flexible cables of up to 10 m in length, to a remote data acquisition system that interfaces with a PC through USB3.0 connection. We present the design and performance of a prototype multi-channel readout system that can read out up to 24 detector modules synchronously. Our experimental results demonstrated that the readout circuitry offers an ultrahigh spectral resolution (0.8 keV at 60 keV and 1.05 keV at 122 keV) with the Cd(Zn)Te/HEXITEC ASIC modules tested. This architecture was designed to allow easy expansion to accommodate a larger number of detector modules, and the flexibility of arranging the detector modules in a large and deformable detector array without degrading the excellent energy resolution.

Preliminary Assessment of a Telehealth Approach to Evaluating, Treating, and Discharging Low-Acuity Patients With Suspected COVID-19

BACKGROUND

Telemedicine is uniquely positioned to address challenges posed to emergency departments (EDs) by the Coronavirus Disease 2019 (COVID-19) pandemic. By reducing in-person contact, it should decrease provider risk of infection and preserve personal protective equipment (PPE).

OBJECTIVES

To describe and assess the early results of a novel telehealth workflow in which remote providers collaborate with in-person nursing to evaluate and discharge well-appearing, low-risk ED patients with suspected COVID-19 infection.

METHODS

Retrospective chart review was completed 3 weeks after implementation. Metrics include the number of patients evaluated, number of patients discharged without in-person contact, telehealth wait time and duration, collection of testing, ED length of stay (ED-LOS), 72-h return, number of in-person health care provider contacts, and associated PPE use.

RESULTS

Among 302 patients evaluated by telehealth, 153 patients were evaluated and discharged by a telehealth provider with reductions in ED-LOS, PPE use, and close contact with health care personnel. These patients had a 62.5% shorter ED-LOS compared with other Emergency Severity Index level 4 patients seen over the same time period. Telehealth use for these 153 patients saved 413 sets of PPE. We observed a 3.9% 72-h revisit rate. One patient discharged after telehealth evaluation was hospitalized on a return visit 9 days later.

CONCLUSION

Telehealth can be safely and efficiently used to evaluate, treat, test, and discharge ED patients suspected to have COVID-19. This workflow reduces infection risks to health care providers, PPE use, and ED-LOS. Additionally, it allows quarantined but otherwise well clinicians to continue working.

Central Adjudication Identified Additional and Prognostically Important Myocardial Infarctions in Patients Undergoing Percutaneous Coronary Intervention

BACKGROUND

In the CHAMPION PHOENIX trial, cangrelor reduced the primary composite end point of death, myocardial infarction (MI), ischemia-driven revascularization, or stent thrombosis at 48 hours. This study aimed to explore the impact of event adjudication and the prognostic importance of MI reported by a clinical events committee (CEC) or site investigators (SIs).

METHODS AND RESULTS

Data from the CHAMPION PHOENIX trial of patients undergoing elective or nonelective percutaneous coronary intervention were analyzed. A CEC systematically identified and adjudicated MI using predefined criteria, a computer algorithm to identify suspected events, and semilogarithmic plots to review biomarker changes. Thirty-day death was modeled using baseline characteristics. Of 10 942 patients, 462 (4.2%) patients had at least 1 MI by 48 hours identified by the CEC (207 [3.8%] cangrelor; 255 [4.7%] clopidogrel; odds ratio [OR] 0.80; 95% CI, 0.67-0.97; P=0.022), and 143 patients had at least 1 MI by 48 hours reported by the SI (60 [1.1%] cangrelor; 83 [1.5%] clopidogrel; OR, 0.72; 95% CI, 0.52-1.01; P=0.053). Of the 462 MIs identified by the CEC, 92 (20%) were reported by SI, and 370 (80%) were not. Of the 143 MI reported by the SI, 51 (36%) were not confirmed by CEC. All categories were associated with an increased adjusted risk for 30-day death (CEC: OR, 5.35; 95% CI, 2.56-11.2; P<0.001; SI: 9.08 [4.01-20.5]; P<0.001; CEC and SI: 10.9 [3.23-36.6]; P<0.001; CEC but not SI: 4.69 [1.94-11.3]; P<0.001; SI but not CEC: 15.4 [5.26-44.9]; P<0.001).

CONCLUSIONS

In patients undergoing percutaneous coronary intervention, CEC procedures identified 3 times as many MIs as the SI reported. Compared with clopidogrel, cangrelor significantly reduced MIs identified by the CEC with a qualitatively similar relative risk reduction in MIs reported by the SI. MIs identified by CEC or reported by SI were independently associated with worse 30-day death. Central adjudication identified additional, prognostically important events.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01156571.

The Incidence of Nonunion of the Naviculocuneiform Joint Arthrodesis:A Systematic Review

Naviculocuneiform (NC) joint arthrodesis is an effective procedure to treat pain and provide stability to the medial column. Various forms of fixation have been described for NC arthrodesis. Despite this, the available literature is scant and questions remain regarding nonunion rate and contributory factors. A systematic review of the literature was undertaken to determine the rate of nonunion for NC joint arthrodesis. Seven studies involving 139 NC joint arthrodeses met inclusion criteria. The nonunion rate was 6.5% at a weighted mean follow-up of 73.2 months. There is insufficient evidence to provide a practice guideline based on the current literature. Adequately powered prospective clinical trials comparing well-matched patient groups with long-term follow-up are required to limit systematic error and enhance external validity. Specific outcomes measures should include union, functional assessment, complications, and cost-benefit analysis.

A prospective RCT comparing combined chromoendoscopy with water exchange (CWE) vs water exchange (WE) vs air insufflation (AI) in adenoma detection in screening colonoscopy

Background

A low adenoma detection rate (ADR) increases risks of interval cancers (ICs). Proximal colon flat polyps, e.g. serrated lesions (SLs), are difficult to find. Missed proximal colon flat lesions likely contribute to IC.

Aims

We compared chromoendoscopy with water exchange (CWE), water exchange (WE) and air insufflation (AI) in detecting adenomas in screening colonoscopy.

Methods

After split-dose preparation, 480 veterans were randomized to AI, WE and CWE.

Results

Primary outcome of proximal ADR (55.6% vs 53.4% vs 52.2%, respectively) were similar in all groups. Adenoma per colonoscopy (APC) and adenoma per positive colonoscopy (APPC) were comparable. Detection rate of proximal colon SLs was significantly higher for CWE and WE than AI (26.3%, 23.6% and 11.3%, respectively, p = 0.002). Limitations: single operator; SLs only surrogate markers of but not IC.

Conclusions

When an endoscopist achieves high-quality AI examinations with overall ADR twice (61.6%) the recommended standard (30%), use of WE and CWE does not produce further improvement in proximal or overall ADR. Comparable APC and APPC confirm equivalent withdrawal inspection techniques. WE alone is sufficient to significantly improve detection of proximal SLs. The impact of increased detection of proximal SLs by WE on prevention of IC deserves to be studied. This study is registered at ClinicalTrial.gov (NCT#01607255).

Incidence of Nonunion of the Hallux Interphalangeal Joint Arthrodesis: A Systematic Review

Hallux interphalangeal joint arthrodesis is an effective procedure to treat pain and provide stability and is often performed for intrinsic pain to the hallux interphalangeal joint. Additionally, this procedure is typically used in concert with the Jones tenosuspension. Although this as an accepted technique, the available data are scant, and questions remain regarding nonunion rates and contributory factors to poor healing. A systematic review of the reported data were undertaken to determine the rate of nonunion for hallux interphalangeal joint arthrodesis. Seven studies involving 313 hallux interphalangeal joint arthrodeses met the inclusion criteria. The nonunion rate was 28.3% at a weighted mean follow-up period of 8.4 months. The overall complication rate was 33.0%. Considering the increased rate of complications and nonunion rate for this commonly used procedure, additional prospective comparative analyses are needed regarding this topic to identify important patient demographic data and determine superior fixation constructs.

Antithrombotic Reversal Agents

The actively bleeding anticoagulated patient presenting to the emergency department requires rapid evaluation and treatment, which is made increasingly complicated by the ever-evolving antithrombotic treatment options used in medicine. Even with excellent supportive care, the timeliness with which reversal decisions need to be made continues to demand of the emergency practitioner a familiarity with the properties and general characteristics of a variety of antithrombotic agents. Reversal options vary and may include vitamin K, FFP, PCC, rFVIIa, platelets, and desmopressin, among others.

High Energy Resolution Hyperspectral X-Ray Imaging for Low-Dose Contrast-Enhanced Digital Mammography

Contrast-enhanced digital mammography (CEDM) is an alternative to conventional X-ray mammography for imaging dense breasts. However, conventional approaches to CEDM require a double exposure of the patient, implying higher dose, and risk of incorrect image registration due to motion artifacts. A novel approach is presented, based on hyperspectral imaging, where a detector combining positional and high-resolution spectral information (in this case based on Cadmium Telluride) is used. This allows simultaneous acquisition of the two images required for CEDM. The approach was tested on a custom breast-equivalent phantom containing iodinated contrast agent (Niopam 150®). Two algorithms were used to obtain images of the contrast agent distribution: K-edge subtraction (KES), providing images of the distribution of the contrast agent with the background structures removed, and a dual-energy (DE) algorithm, providing an iodine-equivalent image and a water-equivalent image. The high energy resolution of the detector allowed the selection of two close-by energies, maximising the signal in KES images, and enhancing the visibility of details with the low surface concentration of contrast agent. DE performed consistently better than KES in terms of contrast-to-noise ratio of the details; moreover, it allowed a correct reconstruction of the surface concentration of the contrast agent in the iodine image. Comparison with CEDM with a conventional detector proved the superior performance of hyperspectral CEDM in terms of the image quality/dose tradeoff.

Acute Kidney Injury as a Risk Factor for Delirium and Coma during Critical Illness

RATIONALE

Acute kidney injury may contribute to distant organ dysfunction. Few studies have examined kidney injury as a risk factor for delirium and coma.

OBJECTIVES

To examine whether acute kidney injury is associated with delirium and coma in critically ill adults.

METHODS

In a prospective cohort study of intensive care unit patients with respiratory failure and/or shock, we examined the association between acute kidney injury and daily mental status using multinomial transition models adjusting for demographics, nonrenal organ failure, sepsis, prior mental status, and sedative exposure. Acute kidney injury was characterized daily using the difference between baseline and peak serum creatinine and staged according to Kidney Disease Improving Global Outcomes criteria. Mental status (normal vs. delirium vs. coma) was assessed daily with the Confusion Assessment Method for the ICU and Richmond Agitation-Sedation Scale.

MEASUREMENTS AND MAIN RESULTS

Among 466 patients, stage 2 acute kidney injury was a risk factor for delirium (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.07-2.26) and coma (OR, 2.04; 95% CI, 1.25-3.34) as was stage 3 injury (OR for delirium, 2.56; 95% CI, 1.57-4.16) (OR for coma, 3.34; 95% CI, 1.85-6.03). Daily peak serum creatinine (adjusted for baseline) values were also associated with delirium (OR, 1.35; 95% CI, 1.18-1.55) and coma (OR, 1.44; 95% CI, 1.20-1.74). Renal replacement therapy modified the association between stage 3 acute kidney injury and daily peak serum creatinine and both delirium and coma.

CONCLUSIONS

Acute kidney injury is a risk factor for delirium and coma during critical illness.

Cardiovascular adverse events in the drug-development program of bupropion for smoking cessation: A systematic retrospective adjudication effort

BACKGROUND

In 2011, the US Food and Drug Administration requested that GlaxoSmithKline perform retrospective adjudication of cardiovascular (CV) events reported in the bupropion drug-development trials for smoking cessation.

HYPOTHESIS

Retrospective adjudication of clinical trial data will not increase the identification of adverse events.

METHODS

We performed a comprehensive retrospective analysis of adverse events in 19 previously completed controlled US clinical trials of bupropion marketed for the treatment of smoking cessation, yielding 9479 subjects (5290 bupropion, 2927 placebo, 1018 active control [ACT], and 244 treated concurrently with bupropion and ACT). All adverse events were sent to the Duke Clinical Research Institute for adjudication by Clinical Events Classification (CEC) physician reviewers. The primary endpoint was a composite of major adverse CV events: CV death, nonfatal myocardial infarction (MI), and nonfatal stroke.

RESULTS

Overall, 416 nonfatal CV events in 366 subjects, and 22 deaths, were identified and processed for adjudication. Of these, 7 nonfatal MIs (4 bupropion, 3 placebo, 0 ACT), 5 nonfatal strokes (1 bupropion, 3 placebo, 1 ACT), and 9 CV deaths (4 bupropion, 4 placebo, 1 ACT) were confirmed by the CEC Committee. The primary endpoint occurred in 3/4297 (0.07%) subjects in the bupropion group and in 4/2927 (0.14%) subjects in the placebo group (log-rank P value: 0.613).

CONCLUSIONS

CV events in bupropion clinical trials for smoking cessation were uncommon, with no observed increase among subjects assigned to bupropion vs placebo. However, this effort was limited by a paucity of quality data.

Single nucleotide polymorphisms in an intergenic chromosome 2q region associated with tissue factor pathway inhibitor plasma levels and venous thromboembolism

Essentials Tissue factor pathway inhibitor (TFPI) regulates the blood coagulation cascade. We replicated previously reported linkage of TFPI plasma levels to the chromosome 2q region. The putative causal locus, rs62187992, was associated with TFPI plasma levels and thrombosis. rs62187992 was marginally associated with TFPI expression in human aortic endothelial cells. Click to hear Ann Gil's presentation on new insights into thrombin activatable fibrinolysis inhibitor SUMMARY: Background Tissue factor pathway inhibitor (TFPI) regulates fibrin clot formation, and low TFPI plasma levels increase the risk of arterial thromboembolism and venous thromboembolism (VTE). TFPI plasma levels are also heritable, and a previous linkage scan implicated the chromosome 2q region, but no specific genes. Objectives To replicate the finding of the linkage region in an independent sample, and to identify the causal locus. Methods We first performed a linkage analysis of microsatellite markers and TFPI plasma levels in 251 individuals from the F5L Family Study, and replicated the finding of the linkage peak on chromosome 2q (LOD = 3.06). We next defined a follow-up region that included 112 603 single nucleotide polymorphisms (SNPs) under the linkage peak, and meta-analyzed associations between these SNPs and TFPI plasma levels across the F5L Family Study and the Marseille Thrombosis Association (MARTHA) Study, a study of 1033 unrelated VTE patients. SNPs with false discovery rate q-values of < 0.10 were tested for association with TFPI plasma levels in 892 patients with coronary artery disease in the AtheroGene Study. Results and Conclusions One SNP, rs62187992, was associated with TFPI plasma levels in all three samples (β = + 0.14 and P = 4.23 × 10-6 combined; β = + 0.16 and P = 0.02 in the F5L Family Study; β = + 0.13 and P = 6.3 × 10-4 in the MARTHA Study; β = + 0.17 and P = 0.03 in the AtheroGene Study), and contributed to the linkage peak in the F5L Family Study. rs62187992 was also associated with clinical VTE (odds ratio 0.90, P = 0.03) in the INVENT Consortium of > 7000 cases and their controls, and was marginally associated with TFPI expression (β = + 0.19, P = 0.08) in human aortic endothelial cells, a primary site of TFPI synthesis. The biological mechanisms underlying these associations remain to be elucidated.

Metastatic bone disease: A review of survival, prognostic factors and outcomes following surgical treatment of the appendicular skeleton

Survival data and prognostic factors may help to provide insight when deciding on the appropriate orthopaedic treatment for patients presenting with metastatic bone disease. This review was conducted to look at the outcomes following orthopaedic surgery for metastatic lesions in the extremities. The literature was identified through the Medline and Embase database and further refined via a set of inclusion and exclusion criteria. Overall, patients presenting with metastatic bone disease from renal cell cancer or breast cancer had the longest survival rate. Important factors found to predict prognosis was the presence of visceral metastasis, multiple metastases, pathological fracture and the type of primary tumour involved. These prognostic factors may help to direct future inquiry into metastatic bone disease and help determine the type of surgery to use in a metastatic setting in order to avoid complications and unnecessary revisions as well as provide durability.

Mapping of multi-elements during melting and solidification using synchrotron X-rays and pixel-based spectroscopy

A new synchrotron-based technique for elemental imaging that combines radiography and fluorescence spectroscopy has been developed and applied to study the spatial distribution of Ag, Zr and Mo in an Al alloy during heating and melting to 700, and then re-soldification. For the first time, multi-element distributions have been mapped independently and simultaneously, showing the dissolution of Ag- and Zr-rich particles during melting and the inter-dendritic segregation of Ag during re-solidification. The new technique is shown to have wide potential for metallurgical and materials science applications where the dynamics of elemental re-distribution and segregation in complex alloys is of importance.

Full-field energy-dispersive powder diffraction imaging using laboratory X-rays

A laboratory instrument with the ability to spatially resolve energy-dispersed X-ray powder diffraction patterns taken in a single snapshot has been developed. The experimental arrangement is based on a pinhole camera coupled with a pixelated spectral X-ray detector. Collimation of the diffracted beam is defined by the area of the footprint of a detector pixel and the diameter of the pinhole aperture. Each pixel in the image, therefore, contains an energy-dispersed powder diffraction pattern. This new X-ray imaging technique enables spatial mapping of crystallinity, crystalline texture or crystalline phases from within a sample. Validation of the method has been carried out with a back-to-back comparison with crystalline texture mapping local to a friction stir weld in an aluminium alloy taken using synchrotron radiation.

Urban-rural differences in the gene expression profiles of Ghanaian children

Recent studies indicate that urbanization is having a pronounced effect on disease patterns in developing countries. To understand the immunological basis of this, we examined mRNA expression in whole blood of genes involved in immune activation and regulation in 151 children aged 5-13 years attending rural, urban low socioeconomic status (SES) and urban high-SES schools in Ghana. Samples were also collected to detect helminth and malaria infections. Marked differences in gene expression were observed between the rural and urban areas as well as within the urban area. The expression of both interleukin (IL)-10 and programmed cell death protein 1 increased significantly across the schools from urban high SES to urban low SES to rural (P-trend <0.001). Although IL-10 gene expression was significantly elevated in the rural compared with the urban schools (P<0.001), this was not associated with parasitic infection. Significant differences in the expression of toll-like receptors (TLRs) and their signaling genes were seen between the two urban schools. Genetic differences could not fully account for the gene expression profiles in the different groups as shown by analysis of IL-10, TLR-2 and TLR-4 gene polymorphisms. Immune gene expression patterns are strongly influenced by environmental determinants and may underlie the effects of urbanization seen on health outcomes.

Dark-field hyperspectral X-ray imaging

In recent times, there has been a drive to develop non-destructive X-ray imaging techniques that provide chemical or physical insight. To date, these methods have generally been limited; either requiring raster scanning of pencil beams, using narrow bandwidth radiation and/or limited to small samples. We have developed a novel full-field radiographic imaging technique that enables the entire physio-chemical state of an object to be imaged in a single snapshot. The method is sensitive to emitted and scattered radiation, using a spectral imaging detector and polychromatic hard X-radiation, making it particularly useful for studying large dense samples for materials science and engineering applications. The method and its extension to three-dimensional imaging is validated with a series of test objects and demonstrated to directly image the crystallographic preferred orientation and formed precipitates across an aluminium alloy friction stir weld section.

Cytotaxonomic description ofSimulium kaffaense, a new member of theS. damnosumcomplex (Diptera: Simuliidae) from south–western Ethiopia

Although Ethiopia is one of the countries worst affected by human onchocerciasis, the exact taxonomic identity of the blackflies acting as the main vectors in the endemic areas has never been determined. A cytotaxonomic analysis of Simulium damnosum s.l. collected from three endemic sites in south-western Ethiopia has now revealed the existence of the 'Kisiwani' form (a non-anthropophilic cytoform that is common in East Africa) and a newly recognized species, Simulium kaffaense. Simulium kaffaense sp. nov. is differentiated from other members of the S. damnosum complex by six fixed inversions and dozens of 'new' floating inversions. The rearing of egg batches from some of the biting adult females, to larvae or adults, indicated that the human-biting blackflies were all S. kaffaense. As S. kaffaense is not only highly anthropophilic but also, apparently, the only anthropophilic member of the S. damnosum complex present, it is likely to be the main (if not the only) vector of Onchocerca volvulus in the study area. The presence of inversion 1S-1 and a complex inversion possibly involving 1L-3 indicates that S. kaffaense either belongs or is close to the 'Nile' phylogenetic group of S. damnosum s. l. The karyotype frequencies of the inversions in the collections from the three study sites indicate that at least two forms of S. kaffaense, here designated 'Bebeka' and 'Jimma', were caught. The taxonomy and medical importance of S. kaffaense are discussed.

Stearidonic and γ-linolenic acids in echium oil improves glucose disposal in insulin resistant monkeys

Echium oil (EO) contains stearidonic acid (18:4), a n-3 polyunsaturated fatty acids (PUFAs), and gamma-linolenic acids (18:3), a n-6 PUFA that can be converted to long chain (LC)-PUFAs. We aimed to compare a safflower oil (SO)-enriched diet to EO- and fish oil (FO)-enriched diets on circulating and tissue PUFAs levels and glycemic, inflammatory, and cardiovascular health biomarkers in insulin resistant African green monkeys. In a Latin-square cross-over study, eight monkeys consumed matched diets for 6 weeks with 3-week washout periods. Monkeys consuming FO had significantly higher levels of n-3 LC-PUFAs and EO supplementation resulted in higher levels of circulating n-3 LC-PUFAs and a significant increase in dihomo-gamma linolenic acid (DGLA) in red blood cells and muscle. Glucose disposal was improved after EO consumption. These data suggest that PUFAs in EO supplementation have the capacity to alter circulating, RBC and muscle LC-PUFA levels and improve glucose tolerance in insulin-resistant monkeys.

Efficacy of DEET and non-DEET-based insect repellents against bites of Simulium damnosum vectors of onchocerciasis

Coping strategies including smoke screens are used against nuisance bites of Simulium damnosum Theobald (Diptera:Simuliidae) in onchocerciasis endemic communities. To find more effective alternatives, the efficacy of commercially available N,N-diethyl-3-methylbenzamide (DEET) products with active concentrations of 9.5, 13, 25, 50 and 98.1-100% and 'NO MAS,' (active component: para-menthane-3,8-diol and lemon grass oil) were tested at Bui-Agblekame, Ghana. A Latin square study design was implemented using eight groups of two vector collectors each, who used repellents (treatment), mineral oil or nothing each day until the end of the study. Flies were caught and their numbers each hour recorded using the standard methods for onchocerciasis transmission studies. T-tests were used to compare the mean duration of protection and a one-way analysis of variance controlling for catchers and repellents was performed. Tukey's test was used to compare protection by repellents and mineral oil. The highest percentage protection was 80.8% by NO MAS and the least 42.5% by the 13% DEET product. The period of absolute protection was 5 h by NO MAS and 1 h by 50% DEET product. No significant increase in protection was offered beyond 25% active DEET products and no significance was observed in terms of catcher × repellent effect (F = 1.731, d.f. = 48, P = 0.209).

In the case of transmission of Mycobacterium ulcerans in buruli ulcer disease Acanthamoeba species stand accused

Buruli ulcer disease caused by Mycobacterium ulcerans results in extensive destruction of skin and soft tissue and long-term functional disabilities that ultimately require surgery and rehabilitation. The disease is associated with aquatic and swampy environments with the mycobacterium occurring in biofilms, soil, aquatic insects, fish and wildlife however, the mode of transmission to humans remains an enigma. Current transmission ideas including bites from predatory water bugs and mosquitoes, do not explain satisfactorily the spasmodic disease distribution in human populations. Here we argue that Acanthamoeba species are the natural hosts of M. ulcerans and are mainly responsible for disease transmission because; (i) Acanthamoebae are known natural hosts of several microbial pathogens including M. marinum, M. avium and Legionella pneumophila, (ii) culture of slow-to-grow microbial pathogens hosted in nature by Acanthamoeba spp is enhanced when the media is seeded with the protozoa, (iii) acanthamoebae and M. ulcerans share similar bio-ecological and epidemiological settings, (iv) documented evidence that prior growth of L. pneumophila and M. avium in acanthamoebae influences entry mechanisms, intracellular growth and virulence in human monocytes, (v) Acanthamoeba spp also infect humans and cause diseases via routes of openings including broken skin and sites of trauma similar to M. ulcerans and (vi) M. ulcerans is rather a fastidious intracellular organism as recent analysis of the genome indicate. We argue further that temperature plays a significant role in transmission determining the fate of either the intracellular microbe or the host cells. Also, Acanthamoeba-pathogen association has a long evolutionary history because the same set of bacterial genes and gene products e.g. in L. pneumophila are required for survival in both mammalian and protozoan host cells. We suggest that the involvement of Acanthamoeba in the transmission of M. ulcerans to humans better explains the disease's epidemiology.

Preformed vs intraoperative bending of titanium mesh for orbital reconstruction

OBJECTIVE

The most accurate orbital reconstructions result from an anatomic repair of the premorbid orbital architecture. Many different techniques and materials have been used; unfortunately, there is currently no optimal method. This study compares the use of preformed vs intraoperative bending of titanium mesh for orbital reconstruction in 2-wall orbital fractures.

STUDY DESIGN

Cadaver-based study.

SETTING

University hospital.

SUBJECTS AND METHODS

Preinjury computed tomography scans were obtained in 15 cadaveric heads (30 orbits). Stereolithographic (STL) models were fabricated for 5 of the specimens (10 orbits). Two wall fractures (lamina papyracea and floor) were then generated in all orbits. Surgical reconstruction was performed in all orbits using 1 of 3 techniques (10 orbits each): (1) patient-specific implant molded from the preinjury STL model, (2) titanium mesh sheet bent freehand, and (3) preformed titanium mesh. Each technique was evaluated for orbital volume correction, contour accuracy, ease of use, and cost.

RESULTS

No difference in volume restoration was found between the 3 techniques. Patient-specific implants had the greatest contour accuracy, poor ease of use, and highest cost. Freehand bending implants had the poorest contour accuracy, acceptable ease of use, and lowest cost. Preformed mesh implants had intermediate contour accuracy, excellent ease of use, and low cost.

CONCLUSION

All 3 techniques provide equivalent orbital volume correction. However, preformed mesh implants have many advantages based on contour accuracy, ease of use, and relative cost.

Communicating in the pre-hospital emergency environment

AIM

To develop and evaluate the implementation of a communication board for paramedics to use with patients as an augmentative or alternative communication tool to address communication needs of patients in the pre-hospital setting.

METHOD

A double-sided A4-size communication board was designed specifically for use in the pre-hospital setting by the Queensland Ambulance Service and Disability and Community Care Services. One side of the board contains expressive messages that could be used by both the patient and paramedic. The other side contains messages to support patients' understanding and interaction tips for the paramedic. The communication board was made available in every ambulance and patient transport vehicle in the Brisbane Region.

RESULTS

A total of 878 paramedics completed a survey that gauged which patient groups they might use the communication board with. The two most common groups were patients from culturally and linguistically diverse backgrounds and children. Staff reported feeling confident in using the board, and 72% of interviewed paramedics agreed that the communication board was useful for aiding communication with patients. Feedback from paramedics suggests that the board is simple to use, reduces patient frustration and improves communication.

CONCLUSION

These results suggest that a communication board can be applied in the pre-hospital setting to support communication success with patients. WHAT IS KNOWN ABOUT THE TOPIC? It is imperative that communication between patient and paramedic is clear and effective. Research has shown that communication boards have been effective with people with temporary or permanent communication difficulties. WHAT DOES THIS PAPER ADD? This is the first paper outlining the development and use of a communication board by paramedics in the pre-hospital setting in Australia. The paper details the design of the communication board for the unique pre-hospital environment. The paper provides some preliminary data on the use of the communication board with certain patient groups and its effectiveness as an alternative communication tool. WHAT ARE THE IMPLICATIONS FOR PRACTITIONERS? The findings support the use of the tool as a viable option in supporting the communication between paramedics and a range of patients. It is not suggested that this communication board will meet the complete communication needs of any individual in this environment, but it is hoped that the board's presence within the Queensland Ambulance Service may result in paramedics introducing the board on occasions where communication with a patient is challenging.

A procedure for increasing oral reading rate in hard-of-hearing children

This study investigated the effects of systematic training on the oral reading rate of four hard-of-hearing children. In training, systematic increases in pulsing rate of a vibrotactile stimulus were arranged. The children received points, exchangeable for money when their reading rate equalled the pulse rate of the stimulus. The training procedure was effective in increasing the oral reading rate in all children. Generalized increases in reading rate on untrained word lists, sentences, and paragraphs were also observed.

The elimination of the onchocerciasis vector from the island of Bioko as a result of larviciding by the WHO African Programme for Onchocerciasis Control

The island of Bioko is part of the Republic of Equatorial Guinea and is the only island in the World to have endemic onchocerciasis. The disease is hyperendemic and shows a forest-type epidemiology with low levels of blindness and high levels of skin disease, and the whole population of 68,000 is estimated to be at risk. Control of onchocerciasis began in 1990 using ivermectin and this yielded significant clinical benefits but transmission was not interrupted. Feasibility and preparatory studies carried out between 1995 and 2002 confirmed the probable isolation of the vector on the island, the high vectorial efficiency of the Bioko form of Simulium yahense, the seasonality of river flow, blackfly breeding and biting densities, and the distribution of the vector breeding sites. It was proposed that larviciding should be carried out from January to April, when most of the island's rivers were dry or too low to support Simulium damnosum s.l., and that most rivers would not need to be treated above 500 m altitude because they were too small to support the breeding of S. damnosum s.l. Larviciding (with temephos) would need to be carried out by helicopter (because of problems of access by land), supplemented by ground-based delivery. Insecticide susceptibility trials showed that the Bioko form was highly susceptible to temephos, and insecticide carry was tested in the rivers by assessing the length of river in which S. damnosum s.l. larvae were killed below a temephos dosing point. Regular fly catching points were established in 1999 to provide pre-control biting densities, and to act as monitoring points for control efforts. An environmental impact assessment concluded that the proposed control programme could be expected to do little damage, and a large-scale larviciding trial using ground-based applications of temephos (Abate 20EC) throughout the northern (accessible) part of the island was carried out for five weeks from 12 February 2001. Following this, a first attempt to eliminate the vectors was conducted using helicopter and ground-based applications of temephos from February to May 2003, but this was not successful because some vector populations persisted and subsequently spread throughout the island. A second attempt from January to May 2005 aimed to treat all flowing watercourses and greatly increased the number of treatment points. This led to the successful elimination of the vector. The last biting S. damnosum s.l. was caught in March 2005 and none have been found since then for more than 3 years.

An 18S ribosomal DNA barcode for the study of Isomermis lairdi, a parasite of the blackfly Simulium damnosum s.l

The mermithid parasite, Isomermis lairdi Mondet, Poinar & Bernadou (Nematoda: Mermithidae), is known to have a major impact on populations of Simulium damnosum s.l. Theobald (Diptera: Simuliidae) and on their efficiency as vectors of Onchocerca volvulus (Leuckart) (Nematoda: Filarioidea). However, the value of I. lairdi and other mermithid parasites as potential means of integrated vector control has not been fully realized. This is partly because traditional taxonomic approaches have been insufficient for describing and analysing important aspects of their biology and host range. In total, rDNA barcode sequences have been obtained from over 70 I. lairdi mermithids found parasitizing S. damnosum s.l. larvae in three different rivers. No two sequences were found to vary by more than 0.5%, and cytospecies identification of mermithid hosts revealed that I. lairdi with identical rDNA barcodes can parasitize multiple cytoforms of the S. damnosum complex, including S. squamosum (Enderlein). Phylogenetic analysis using a partial sequence from the 18S ribosomal DNA barcode, grouped I. lairdi in a monophyletic group with Gastromermis viridis Welch (Nematoda: Mermithidae) and Isomermis wisconsinensis Welch (Nematoda: Mermithidae).

Field and laboratory studies on water conditions affecting the potency of VectoBac (Bacillus thuringiensis serotype H-14) against larvae of the blackfly, Simulium damnosum

River water conditions that might influence the efficacy of VectoBac, a formulation of the microbial insecticide Bacillus thuringiensis H-14 Berliner against Simulium damnosum sensu lato Theobald (Diptera: Simuliidae) larvae were investigated. A standard formulation was assayed 130 times over 15 months using a mini-gutter system at a field station beside the River Pra in Ghana. The lethal concentration (LC) values, river temperature, conductivity, turbidity and pH were analysed using univariate and multivariate statistics to identify which of these parameters influenced its performance. River temperature, conductivity and turbidity (in that order) were identified as having direct effects on the potency of VectoBac. Water temperature and conductivity were negatively correlated, whereas turbidity and pH were positively correlated with LC values. Analyses of river water samples revealed that despite observed differences in total solids, sodium and potassium cations and chloride concentrations, all the parameters measured did not differ significantly between wet and dry seasons. A simple method for rearing S. damnosum s.l. in the laboratory was then adopted to study the effect of conductivity on potency of VectoBac under controlled conditions. Increasing the conductivity of the water medium up to 3,000 microS enhanced potency by about 42%, whereas increasing that of the insecticide alone raised it by 37%. The results obtained suggest that for effective use of VectoBac for blackfly control in West Africa, river temperature, conductivity and turbidity should be taken into consideration, perhaps by only selecting rivers with optimal conditions for treatment. The laboratory-based system developed for assaying the product overcomes the vagaries associated with field conditions and also the demand for huge logistic requirements of the mini-gutter system, which has to be sited near rivers.

Species abundance and insecticide resistance of Anopheles gambiae in selected areas of Ghana and Burkina Faso

The Ghanaian National Malaria Control Programme has prioritized insecticide-treated materials as a key strategy for malaria control. We report on a survey of the distribution of the molecular forms of Anopheles gambiae Giles (Diptera: Culicidae) and insecticide resistance (the kdr mutation), carried out by sampling mosquitoes from 11 locations in Ghana and one additional site in Burkina Faso. The molecular M and S forms of An. gambiae were found to occur in sympatry in southern Ghana. The S form predominated throughout its distribution in the coastal savannah, except at one location in the strand and mangrove zone where rice was cultivated. The M form was the only form collected in northern Ghana and was the predominant form (97.5%) in Burkina Faso. No M/S hybrids were detected. The kdr mutation was observed at very high frequencies (98-100%) within the S form but reached a maximum of only 3.38% in the M form in one population at an irrigation scheme in the Ghanaian coastal savannah zone.

Vector competence, for Wuchereria bancrofti, of the Anopheles populations in the Bongo district of Ghana

The ability of vector mosquitoes to transmit the microfilariae (mff) of Wuchereria bancrofti, especially when the levels of microfilaraemia in the humans on which the mosquitoes are feeding are very low, is very important for understanding the transmission dynamics of lymphatic filariasis. Data on the correlation between vector competence and the microfilarial load in the human host are also relevant to those trying to improve transmission models for this disease. The majority of the relevant studies have involved culicine rather than anopheline vectors. The competence of populations of Anopheles mosquitoes to transmit W. bancrofti in a district in the Upper East region of Ghana has now been investigated. The wild mosquitoes that fed on 20 volunteers under natural conditions were collected hourly during the night, from 21.00 hours on one day to 06.00 hours on the next. Overall, 1348 fed female mosquitoes--665 Anopheles, 662 Culex and 21 Aedes--were collected. Approximately 50% of the mosquitoes caught were killed immediately post-collection and dissected so that the number of W. bancrofti mff each had ingested could be counted. The remaining mosquitoes where dissected when they died (if this was within 12 days of collection) or when they were killed on day 12 post-collection. With the exception of one Culex mosquito that harboured one microfilaria, none of the Culex and Aedes mosquitoes were found infected with W. bancrofti. All of the other mosquitoes found infected were An. gambiae s.l. or An. funestus. When fingerprick samples of blood, collected hourly from the volunteers during the mosquito infection, were used to estimate the microfilaraemias in the blood on which these mosquitoes had fed, microfilarial uptake and the number of developing larvae were found to vary considerably even when the microfilaraemias in the bloodmeal source were similar. The results of a regression analysis on the pooled data for the Anopheles mosquitoes indicated the process of limitation, although larger samples need to be investigated to determine whether this process occurs only in An. gambiae s.l. or An. funestus or in both of these taxa.

A molecular marker for the identification of Simulium squamosum (Diptera: Simuliidae)

All except one of the important groups of West African vectors of Onchocerca volvulus that lie within the Simulium damnosum complex can be distinguished from each other using morphological characteristics. The exception is S. squamosum, which overlaps with other species, and this results in significant levels of misidentification. Variation in the untranscribed H3-H4 histone intergenic spacer region of flies of the S. damnosum complex has now been investigated. Although a CAA/CAG microsatellite was found to be hyper-variable and unsuitable for species diagnosis, a 10-bp indel seemed to vary in a species-specific manner. This indel was apparently absent from S. squamosum but present in all of the other species tested (S. damnosum s.s., S. sirbanum, S yahense, S. sanctipauli and S. leonense/konkourense). It should now be possible to identify individual, adult, female S. squamosum from the absence of the indel, using a PCR-based amplification and agarose- or polyacrylamide-gel electrophoresis, thus removing the major barrier to the routine identification of unknown samples.

Comparative bias associated with various estimates of dose to maximally exposed individuals

Protection of the environment from anthropogenic radiation is a resurging international interest. The paradigm currently in use argues that the population is adequately protected if dose rates to the maximally exposed individuals are below a certain limit. Based on data sampled from natural populations, resource managers need to be able to test the hypothesis that dose rates to the maximally exposed individuals are acceptable. Recognizing the difficulty of sampling the maximally exposed individual within a contaminated environment, risk assessors have used various alternative approaches that vary from changing the paradigm and applying recommended dose rate limits to representatively, rather than maximally, exposed individuals, to using the 95th percentile of the sample mean as an estimator of the population maximum. To determine the effectiveness of numerous proposed alternatives, we used computer simulation techniques to generate a "population" of doses with known distributional qualities and then mathematically "sampled" the population to compare the ability of the various statistics at estimating the known population maximum. The simulation procedure was repeated 1000 times using Monte Carlo techniques, each time producing a measure of the distance between the estimate and the true value. We were thus able to quantify the bias associated with several approaches used to determine compliance with dose rate criteria established by the Department of Energy for protecting biota. The 95th quantile of the sample mean, and the sample maximum underestimated the population maximum by as much as 72 and 44%, respectively. The maximum likelihood estimate (MLE) of the 99.99th percentile was found to be the best predictor of the population maximum, even for small sample sizes of 20 and for both normally and lognormally distributed populations. However, bias associated with the MLE increased significantly if the population's distribution was incorrectly identified. We suggest shifting the regulatory criterion appropriately to argue that if the top 1% (as opposed to the maximum) of the population has a dose rate less than or equal to the regulatory limit then the population is adequately protected, and then using the MLE of the 99th percentile as the least biased sample statistic. Results of this study are also relevant when estimating dose to critical sub-groups of humans whose lifestyles are such that their doses are among the maximum for the population.

Cytotaxonomy, morphology and molecular systematics of the Bioko form of Simulium yahense (Diptera: Simuliidae)

Cytotaxonomic analysis of the polytene chromosomes from larvae of the Simulium damnosum Theobald complex from the island of Bioko in Equatorial Guinea is reported, and a new endemic cytoform is described. Chromosomally this cytoform is close to both S. squamosum (Enderlein) and S. yahense Vajime & Dunbar, but is not identical to either. However, it is morphologically and enzymatically identical to S. yahense. The Bioko form was also found to differ from other cytoforms of the S. damnosum complex in West Africa in the copy number or RFLP pattern of several different repetitive DNA sequences. It is clear that the Bioko form is genetically distinct from other populations of the S. damnosum complex, and whilst it is closest to S. yahense, it shows features that suggest a high degree of geographical and genetic isolation. Such isolation is an important consideration in the assessment of the potential for onchocerciasis vector eradication on Bioko.

Apatite and phillipsite as sequestering agents for metals and radionuclides

Laboratory and greenhouse studies were conducted to quantify apatite and phillipsite (zeolite) sequestration of selected metal contaminants. The laboratory batch study measured the sorption of aqueous Co2+, Ba2+, Pb2+, Eu3+, and UO2(2+). Apatite sorbed more Co2+, Pb2+, Eu3+, and UO2(2+) from the spike solution than phillipsite, resulting in distribution coefficients (Kd values) of >200,000 L kg(-1). Phillipsite was more effective than apatite at sorbing aqueous Ba2+. Results from the laboratory study were used to design the greenhouse study that used a soil affected by a Zn-Pb smelter from Pribram, Czech Republic. Two application rates (25 and 50 g kg(-1)) of phillipsite and apatite and two plant species, maize (Zea mays L.) and oat (Avena sativa L.), were evaluated in this study. There was little (maize) to no (oat) plant growth in the unamended contaminated soil. Apatite and, to a slightly lesser extent, phillipsite additions significantly enhanced plant growth and reduced Cd, Pb, and Zn concentrations in all analyzed tissues (grain, leaves, and roots). The sequestering agents also affected some essential elements (Ca, Fe, and Mg). Phillipsite reduced Fe and apatite reduced P and Fe concentrations in oat tissues; however, the level of these elements in oat leaves and grains remained sufficient. Sequential extractions of the soil indicated that the Cd, Pb, and Zn were much more strongly sorbed onto the amended soil, making the contaminants less phytoavailable.

Completion of the sequence of the nuclear ribosomal DNA subunit of Simulium sanctipauli, with descriptions of the 18S, 28S genes and the IGS

We describe the IGS-ETS, 18S and 28S ribosomal gene sequences of Simulium sanctipauli Vajime & Dunbar, a member of the S. damnosum Theobald (Diptera: Simuliidae) complex of blackflies (Diptera: Simuliidae). These regions, together with the ITS-1, ITS-2 and 5.8S rDNA presented elsewhere (accession number U36206), constitute the composite sequence of the entire rDNA unit, making S. sanctipauli the second dipteran species of medical importance for which the entire rDNA has been sequenced. Despite the lack of sequence identity, the IGS of S. sanctipauli showed some structural similarities to other Diptera, i.e. the mosquito Aedes albopictus Skuse (Culicidae), the fruitfly Drosophila melanogaster Meigen (Drosophilidae) and the tsetse Glossina (Glossinidae). Two blocks of tandemly repeated subunits were present in the IGS of S. sanctipauli and, unlike other species of Diptera, they contained no duplications of promoter-like sequences. However, two promoter-like sequences were identified in the unique DNA stretches of the IGS by their sequence similarity to the promoter of Aedes aegypti L. (Diptera: Culicidae). The observed sequence variation can be explained, as in the case of Drosophila spp., by the occurrence of slippage-like and point mutation processes, with unequal crossing-over homogenizing (to a certain extent) the region throughout the gene family and blackfly population. The 18S and 28S rDNA genes show more intraspecific variability within the expansion segments than in the core regions. This is also the case in the interspecific comparison of these genes from S. sanctipauli with those of Simulium vittatum, Ae. albopictus and D. melanogaster. This pattern is typical of many eukaryotes and likely to be the result of a more relaxed functional selection in the expansion segments than on the core regions. The A + T content of the S. sanctipauli genes is high and similar to those of other Diptera. This could be the result of a change in the mutation pressure towards AT in the Diptera lineage.

Assessment of rDNA IGS as a molecular marker in the Simulium damnosum complex

For five cytospecies of the Simulium damnosum Theobald complex of blackflies (Diptera: Simuliidae) from West Africa, both ends of the intergenic spacer region (IGS) of the rDNA have been sequenced with the aim of developing specific molecular markers. No specific differences in these two regions were detected between Simulium sanctipauli V. & D., Simulium sirbanum V. & D., Simulium soubrense V. & D., Simulium squamosum Enderlein and Simulium yahense V. & D., except in the number of A subrepeats at the 5' end of the IGS (two in S. squamosum and four or five in the others) and in position 310 of the 3' end (a C in S. squamosum and a G in the others). However, genetic distances within and between species overlapped. These DNA sequences had no strong phylogenetic signal, and the trees obtained were mostly unresolved. Although most sequences from S. squamosum clustered together, a few of them were more similar to those in other cytospecies. These results could be explained either by hybridization with genetic introgression or by ancestral polymorphism and recent speciation.

Deforestation and the spatio-temporal distribution of savannah and forest members of the Simulium damnosum complex in southern Ghana and south-western Togo

Spatio-temporal data on cytotaxonomic identifications of larvae of different members of the Simulium damnosum complex collected from rivers in southern Ghana and south-western Togo from 1975 until 1997 were analysed. When the data were combined, the percentages of savannah blackflies (S. damnosum sensu stricto and S. sirbanum) in the samples were shown to have been progressively increasing since 1975. The increases were statistically significant (P < 0.001), but the rates of increase were not linear. Further analyses were conducted according to the collection seasons and locations of the samples, to account for possible biases such as savannah flies occurring further south in the dry season or a preponderance of later samples from northern rivers having more savannah flies. These analyses showed that the increasing trend was statistically significant (P < 0.0001) only during the periods April to June and October to December. The presence of adult savannah flies carrying infective larvae (L3) indistinguishable from those of Onchocerca volvulus in the study zone was confirmed by examinations of captured flies. The percentages of savannah flies amongst the human-biting populations and the percentages with L3s in the head were higher during dry seasons than wet seasons and the savannah species were found furthest south (5 degrees 25'N) in the dry season. Comparisons of satellite images taken in 1973 and 1990 over a study area in south-western Ghana encompassing stretches of the Tano and Bia rivers demonstrated that there have been substantial increases in urban and savannah areas, at the expense of forest. This was so not only for the whole images but also for subsamples of the images taken at 1, 2, 4, 8 and 16 km distant from sites alongside the River Tano. At every distance from the river, the percentages of pixels classified as urban or savannah have increased in 1990 compared with 1973, while those classified as degraded or dense forest have decreased. The possibility that the proportionate increases in savannah forms of the vectors of onchocerciasis, and hence in the likelihood of the transmission of savannah strains of the disease in formerly forested areas, were related to the decreases in forest cover is discussed.

Severe gastrointestinal haemorrhage and ischaemic necrosis of the small bowel in a child with 70% full-thickness burns: a case report

Splanchnic ischaemia is an important problem in patients with large burns. This reports the case of an 11-year-old boy with 70% full-thickness TBSA burns who sustained multiple episodes of severe gastrointestinal haemorrhage due to both extensive ischaemic enterocolitis and severe gastric ulceration which required surgical intervention on several occasions. Causative mechanisms of splanchnic ischaemia in this patient including increased mesenteric vascular resistance, abdominal compartment syndrome and enteric feeding, are considered.