Metabolic responses of thermophilic endospores to sudden heat-induced perturbation in marine sediment samples.

Microbially mediated processes in a given habitat tend to be catalyzed by abundant populations that are ecologically adapted to exploit specific environmental characteristics. Typically, metabolic activities of rare populations are limited but may be stimulated in response to acute environmental stressors. Community responses to sudden changes in temperature and pressure can include suppression and activation of different populations, but these dynamics remain poorly understood. The permanently cold ocean floor hosts countless low-abundance microbes including endospores of thermophilic bacteria. Incubating sediments at high temperature resuscitates viable spores, causing the proliferation of bacterial populations. This presents a tractable system for investigating changes in a microbiome's community structure in response to dramatic environmental perturbations. Incubating permanently cold Arctic fjord sediments at 50°C for 216 h with and without volatile fatty acid amendment provoked major changes in community structure. Germination of thermophilic spores from the sediment rare biosphere was tracked using mass spectrometry-based metabolomics, radiotracer-based sulfate reduction rate measurements, and high-throughput 16S rRNA gene sequencing. Comparing community similarity at different intervals of the incubations showed distinct temporal shifts in microbial populations, depending on organic substrate amendment. Metabolite patterns indicated that amino acids and other sediment-derived organics were decomposed by fermentative Clostridia within the first 12-48 h. This fueled early and late phases of exponential increases in sulfate reduction, highlighting the cross-feeding of volatile fatty acids as electron donors for different sulfate-reducing Desulfotomaculia populations. The succession of germinated endospores triggered by sudden exposure to high temperature and controlled by nutrient availability offers a model for understanding the ecological response of dormant microbial communities following major environmental perturbations.

Thermogenic hydrocarbon biodegradation by diverse depth-stratified microbial populations at a Scotian Basin cold seep.

At marine cold seeps, gaseous and liquid hydrocarbons migrate from deep subsurface origins to the sediment-water interface. Cold seep sediments are known to host taxonomically diverse microorganisms, but little is known about their metabolic potential and depth distribution in relation to hydrocarbon and electron acceptor availability. Here we combined geophysical, geochemical, metagenomic and metabolomic measurements to profile microbial activities at a newly discovered cold seep in the deep sea. Metagenomic profiling revealed compositional and functional differentiation between near-surface sediments and deeper subsurface layers. In both sulfate-rich and sulfate-depleted depths, various archaeal and bacterial community members are actively oxidizing thermogenic hydrocarbons anaerobically. Depth distributions of hydrocarbon-oxidizing archaea revealed that they are not necessarily associated with sulfate reduction, which is especially surprising for anaerobic ethane and butane oxidizers. Overall, these findings link subseafloor microbiomes to various biochemical mechanisms for the anaerobic degradation of deeply-sourced thermogenic hydrocarbons.

Formal verification: will the seedling ever flower?

In one sense, formal specification and verification have been highly successful: techniques have been developed in pioneering academic research, transferred to software companies through training and partnerships, and successfully deployed in systems with national significance. Altran UK has been in the vanguard of this movement. This paper summarizes some of our key deployments of formal techniques over the past 20 years, including both security- and safety-critical systems. The impact of formal techniques, however, remains within an industrial niche, and while government and suppliers across industry search for solutions to the problems of poor-quality software, the wider software industry remains resistant to adoption of this proven solution. We conclude by reflecting on some of the challenges we face as a community in ensuring that formal techniques achieve their true potential impact on society.This article is part of the themed issue 'Verified trustworthy software systems'.

Lower limb intracast pressures generated by different types of immobilisation casts.

AIM: To determine if complete, split casts and backslabs [plaster of Paris (POP) and fiberglass] generate different intracast pressures and pain. METHODS: Increased swelling within casts was modeled by a closed water system attached to an expandable bag placed directly under different types of casts applied to a healthy lower limb. Complete fiberglass and POP casts, split casts and backslabs were applied. Twenty-five milliliter aliquots of saline were injected into the system and the generated intracast pressures were measured using a sphygmomanometer. The subject was blinded to the pressure scores to avoid bias. All casts were applied to the same right limb on the same subject to avoid the effects of variations in anatomy or physiology on intracast pressures. Pain levels were evaluated using the Visual Analogue Score after each sequential saline injection. Each type of cast was reapplied four times and the measurements were repeated on four separate occasions. Sample sizes were determined by a pre-study 90% power calculation to detect a 20% difference in intracast pressures between cast groups. RESULTS: A significant difference between the various types of casts was noted when the saline volume was greater than 100 mL (P = 0.009). The greatest intracast pressure was generated by complete fiberglass casts, which were significantly higher than complete POP casts or backslabs (P = 0.018 and P = 0.008 respectively) at intracast saline volumes of 100 mL and higher. Backslabs produced a significantly lower intracast pressure compared to complete POP only once the saline volume within casts exceeded 225 mL (P = 0.009). Intracast pressures were significantly lower in split casts (P = 0.003). Split POP and fiberglass casts produced the lowest intracast pressures, even compared to backslabs (P = 0.009). Complete fiberglass casts generated the highest pain levels at manometer pressures of 75 mmHg and greater (P = 0.001). Split fiberglass casts had significantly reduced pain levels (P = 0.001). In contrast, a split complete POP cast did not produce significantly reduced pain levels at pressures between 25-150 mmHg. There was no difference in pain generated by complete POP and backslabs at manometer pressures of 200 mmHg and lower. CONCLUSION: Fibreglass casts generate significantly higher intracast pressures and pain than POP casts. Split casts cause lower intracast pressures regardless of material, than complete casts and backslabs.

Climate change, fuel and fire behaviour in a eucalypt forest.

A suite of models was used to examine the links between climate, fuels and fire behaviour in dry eucalypt forests in south-eastern Australia. Predictions from a downscaled climate model were used to drive models of fuel amount, the moisture content of fuels and two models of forest fire behaviour at a location in western Sydney in New South Wales, Australia. We found that a warming and drying climate produced lower fine fuel amounts, but greater availability of this fuel to burn due to lower moisture contents. Changing fuel load had only a small effect on fuel moisture. A warmer, drier climate increased rate of spread, an important measure of fire behaviour. Reduced fuel loads ameliorated climate-induced changes in fire behaviour for one model. Sensitivity analysis of the other fire model showed that changes in fuel amount induced changes in fire behaviour of a similar magnitude to that caused directly by sensitivity to climate. Projection of changes in fire risk requires modelling of changes in vegetation as well as changes in climate. Better understanding of climate change effects on vegetation structure is required.

Angiographic embolisation of pelvic ring injuries. Treatment algorithm and review of the literature.

PURPOSE: The purpose of this study was to evaluate the relation between pelvic fracture patterns and the angiographic findings, and to assess the effectiveness of the embolisation. METHODS: This retrospective study, included patients with pelvic fractures and angiographic evaluation. Demographics, Injury Severity Score (ISS), associated injuries, embolisation time, blood units needed, method of treatment and complications were recorded and analysed. Fractures were classified according to the Burgess system. RESULTS: Between 1998 and 2008, 34 patients with pelvic fractures underwent angiographic investigation. Twenty six were males. The mean age was 41 years. Twenty-seven were motor vehicle accidents and seven were falls. There were 11 anterior posterior (APC) fractures, 12 lateral compression (LC), eight vertical shear (VS) patterns and three with combined mechanical injuries. The median ISS was 33.1 (range 5-66). From the 34 who underwent angiography, 29 had positive vascular extravasations. From them, 21 had embolisation alone, two had vascular repair and embolisation, five required vascular repair alone and one patient died while being prepared for embolisation. Five cases were re-embolised. The findings suggested that AP fractures have a higher tendency to bleeding compared with LC fractures. Both had a higher chance of blood loss compared to VS and complex fracture patterns. We reported 57 additional injuries and 65 fractures. The complications were: one non lethal pulmonary embolism, one renal failure, one liver failure, one systemic infection, two deep infections and two psychological disorientations. Seven patients died in hospital. CONCLUSION: Control of pelvic fracture bleeding is based on the multidisciplinary approach mainly related to hospital facilities and medical personnel's awareness. The morphology of the fracture did not have a predictive value of the vascular lesion and the respective bleeding.

Innovations in osteosynthesis and fracture care.

Over the years giant steps have been made in the evolution of fracture fixation and the overall clinical care of patients. Better understanding of the physiological response to injury, bone biology, biomechanics and implants has led to early mobilisation of patients. A significant reduction in complications during the pre-operative and post-operative phases has also been observed, producing better functional results. A number of innovations have contributed to these improved outcomes and this article reports on the advances made in osteosynthesis and fracture care.

Evaluation of BacLite Rapid MRSA, a rapid culture based screening test for the detection of ciprofloxacin and methicillin resistant S. aureus (MRSA) from screening swabs.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide. The need for accurate and rapid screening methods to detect MRSA carriers has been clearly established. The performance of a novel assay, BacLite Rapid MRSA (Acolyte Biomedica, UK) for the rapid detection (5 h) and identification of hospital associated ciprofloxacin resistant strains of MRSA directly from nasal swab specimens was compared to that obtained by culture on Mannitol salt agar containing Oxacillin (MSAO) after 48 h incubation. RESULTS: A total of 1382 nasal screening swabs were tested by multiple operators. The BacLite Rapid MRSA test detected 142 out of the 157 confirmed MRSA that were detected on MSAO giving a diagnostic sensitivity of 90.4, diagnostic specificity of 95.7% and a negative predictive value of 98.7%. Of the 15 false negatives obtained by the BacLite Rapid MRSA test, seven grew small amounts (< 10 colonies of MRSA) on the MSAO culture plate and five isolates were ciprofloxacin sensitive. However there were 13 confirmed BacLite MRSA positive samples, which were negative by the direct culture method, probably due to overgrowth on the MSAO plate. There were 53 false positive results obtained by the BacLite Rapid MRSA test at 5 h and 115 cases where MRSA colonies were tentatively identified on the MSAO plate when read at 48 h, and which subsequently proved not to be MRSA. CONCLUSION: The BacLite MRSA test is easy to use and provides a similar level of sensitivity to conventional culture for the detection of nasal carriage of MRSA with the advantage that the results are obtained much more rapidly.

Management of ipsilateral pilon and calcaneal fractures: a report of 2 cases.

Although uncommon, the management of ipsilateral pilon and calcaneal fractures is a challenging problem for foot and ankle surgeons. There are several issues that may affect the outcome. Aside from damage to the soft-tissue envelope, technical issues such as positioning of the patient, application of traction, and tourniquet time may complicate surgical intervention. The authors present their experience with 2 patients who sustained this fracture pattern and highlight the mechanism, management, and possible complications of these injuries.

Spontaneous healing of large femoral cortical bone defects: does genetic predisposition play a role?

Traumatic segmental femoral defects are commonly high velocity injuries and their reconstruction necessitates challenging surgical procedures. These injuries present commonly as open fractures and thorough wound debridement followed by adequate soft tissue cover is mandatory before skeletal reconstruction can be commenced. The definitive reconstructive procedure is therefore often delayed and the optimal treatment option is frequently determined by the extent of the cortical defect. The complication rate is high and femoral non-union is not uncommon in these injuries but associated head injuries as part of a polytrauma can have a positive effect on fracture healing. We are presenting a series of four cases, in which traumatic segmental femoral defects of 6, 9, 10 and 15 cm without associated head injury healed spontaneously while the patients were waiting for a definitive skeletal reconstructive procedure.

Medial subtalar dislocation: importance of clinical diagnosis in distinguishing from other dislocations.

In an emergency situation, the clinical picture of ankle and subtalar dislocation may be similar. This may lead to the use of the improper technique of reduction, especially in a subtalar dislocation, resulting in the failure of reduction and further damage to the articular surfaces. A case of medial subtalar dislocation is presented, which was managed as an ankle dislocation and manipulated inappropriately, leading to a failure of reduction. The clinical signs of ankle and subtalar dislocation, including points of differentiation between the two are discussed, and the correct method of reduction of subtalar dislocation is described.

Pseudoaneurysm of the inferior gluteal artery following polytrauma: diverse presentation of a dangerous complication: a report of two cases.

Gluteal artery aneurysms are rare, and the majority of them are pseudoaneurysms secondary to blunt or penetrating trauma. The superior gluteal artery is normally affected. Inferior gluteal artery pseudoaneurysms are uncommon, and review of the literature revealed only 10 cases in the last 30 years. The mainstay of diagnosis is angiography, but these aneurysms may not be visible on an aortic flush angiogram, and super selective angiography may be required to delineate the anatomy. Treatment is either by surgical therapy or minimally invasive techniques, such as embolization, during angiography. We report two cases of pseudoaneurysms of the inferior gluteal artery following pelvic and acetabular trauma, presenting very differently in time and clinical picture. A review of the relevant literature is also presented.

Spinal injuries in motorcycle crashes: patterns and outcomes.

BACKGROUND: The purpose of this study was to determine patterns of spinal injury and clinical outcomes resulting from motorcycle crashes. METHODS: We analyzed data collected on 1,121 motorcyclists involved in road traffic accidents (from 1993-2000) and identified those who had sustained a spinal injury. RESULTS: Spinal injury occurred in 126 (11.2%) riders (112 male riders [88.9%] and 14 female riders [11.1%]), with a mean age of 30.2 years (range, 16-61 years) and Injury Severity Score of 18.8 (range, 4-66). Isolated injuries to the spine occurred in 30 (23.8%) riders. The thoracic spine was injured in 69 (54.8%), the lumbar spine in 37 (29.4%), and the cervical spine in 34 (27.0%) cases. Multiple vertebral levels were affected in 54 (42.9%). Neurologic injury occurred in 25 riders (19.8%), with complete distal neurologic injury in 14 (4 cervical, 9 thoracic, and 1 lumbar). Eleven (8.7%) patients required spinal surgery. There were 13 (10.3%) deaths. CONCLUSION: The thoracic spine is the most commonly injured spinal region in motorcycle crashes. Multiple level injuries are common. Protocols concentrating on the radiographic clearance of the cervical region may miss a significant number of spinal injuries. Vigilance is required in assessing these patients, who often have multiple injuries.