Network analysis identifies strain-dependent response to tau and tau seeding-associated genes

Previous research demonstrated that genetic heterogeneity is a critical factor in modeling amyloid accumulation and other Alzheimer's disease phenotypes. However, it is unknown what mechanisms underlie these effects of genetic background on modeling tau aggregate-driven pathogenicity. In this study, we induced tau aggregation in wild-derived mice by expressing MAPT. To investigate the effect of genetic background on the action of tau aggregates, we performed RNA sequencing with brains of C57BL/6J, CAST/EiJ, PWK/PhJ, and WSB/EiJ mice (n = 64) and determined core transcriptional signature conserved in all genetic backgrounds and signature unique to wild-derived backgrounds. By measuring tau seeding activity using the cortex, we identified 19 key genes associated with tau seeding and amyloid response. Interestingly, microglial pathways were strongly associated with tau seeding activity in CAST/EiJ and PWK/PhJ backgrounds. Collectively, our study demonstrates that mouse genetic context affects tau-mediated alteration of transcriptome and tau seeding. The gene modules associated with tau seeding provide an important resource to better model tauopathy.

The effect of Abi3 locus deletion on the progression of Alzheimer's disease-related pathologies

Human genetics studies of Alzheimer's disease (AD) have identified the ABI3 gene as a candidate risk gene for AD. Because ABI3 is highly expressed in microglia, the brain's immune cells, it was suggested that ABI3 might impact AD pathogenesis by regulating the immune response. Recent studies suggest that microglia have multifaceted roles in AD. Their immune response and phagocytosis functions can have beneficial effects in the early stages of AD by clearing up amyloid-beta (Aβ) plaques. However, they can be harmful at later stages due to their continuous inflammatory response. Therefore, it is important to understand the role of genes in microglia functions and their impact on AD pathologies along the progression of the disease. To determine the role of ABI3 at the early stage of amyloid pathology, we crossed Abi3 knock-out mice with the 5XFAD Aβ-amyloidosis mouse model and aged them until 4.5-month-old. Here, we demonstrate that deletion of the Abi3 locus increased Aβ plaque deposition, while there was no significant change in microgliosis and astrogliosis. Transcriptomic analysis indicates alterations in the expression of immune genes, such as Tyrobp, Fcer1g, and C1qa. In addition to the transcriptomic changes, we found elevated cytokine protein levels in Abi3 knock-out mouse brains, strengthening the role of ABI3 in neuroinflammation. These findings suggest that loss of ABI3 function may exacerbate AD progression by increasing Aβ accumulation and inflammation starting from earlier stages of the pathology.

TREM2 splice isoforms generate soluble TREM2 species that disrupt long-term potentiation

BACKGROUND

TREM2 is a transmembrane receptor expressed by myeloid cells and acts to regulate their immune response. TREM2 governs the response of microglia to amyloid and tau pathologies in the Alzheimer's disease (AD) brain. TREM2 is also present in a soluble form (sTREM2), and its CSF levels fluctuate as a function of AD progression. Analysis of stroke and AD mouse models revealed that sTREM2 proteins bind to neurons, which suggests sTREM2 may act in a non-cell autonomous manner to influence neuronal function. sTREM2 arises from the proteolytic cleavage of the membrane-associated receptor. However, alternatively spliced TREM2 species lacking a transmembrane domain have been postulated to contribute to the pool of sTREM2. Thus, both the source of sTREM2 species and its actions in the brain remain unclear.

METHODS

The expression of TREM2 isoforms in the AD brain was assessed through the analysis of the Accelerating Medicines Partnership for Alzheimer's Disease Consortium transcriptomics data, as well as qPCR analysis using post-mortem samples of AD patients and of the AD mouse model 5xFAD. TREM2 cleavage and secretion were studied in vitro using HEK-293T and HMC3 cell lines. Synaptic plasticity, as evaluated by induction of LTP in hippocampal brain slices, was employed as a measure of sTREM2 actions.

RESULTS

Three distinct TREM2 transcripts, namely ENST00000373113 (TREM2230), which encodes the full-length transmembrane receptor, and the alternatively spliced isoforms ENST00000373122 (TREM2222) and ENST00000338469 (TREM2219), are moderately increased in specific brain regions of patients with AD. We provide experimental evidence that TREM2 alternatively spliced isoforms are translated and secreted as sTREM2. Furthermore, our functional analysis reveals that all sTREM2 species inhibit LTP induction, and this effect is abolished by the GABAA receptor antagonist picrotoxin.

CONCLUSIONS

TREM2 transcripts can give rise to a heterogeneous pool of sTREM2 which acts to inhibit LTP. These results provide novel insight into the generation, regulation, and function of sTREM2 which fits into the complex biology of TREM2 and its role in human health and disease. Given that sTREM2 levels are linked to AD pathogenesis and progression, our finding that sTREM2 species interfere with LTP furthers our understanding about the role of TREM2 in AD.

Network analysis reveals strain-dependent response to misfolded tau aggregates

Mouse genetic backgrounds have been shown to modulate amyloid accumulation and propagation of tau aggregates. Previous research into these effects has highlighted the importance of studying the impact of genetic heterogeneity on modeling Alzheimer's disease. However, it is unknown what mechanisms underly these effects of genetic background on modeling Alzheimer's disease, specifically tau aggregate-driven pathogenicity. In this study, we induced tau aggregation in wild-derived mice by expressing MAPT (P301L). To investigate the effect of genetic background on the action of tau aggregates, we performed RNA sequencing with brains of 6-month-old C57BL/6J, CAST/EiJ, PWK/PhJ, and WSB/EiJ mice (n=64). We also measured tau seeding activity in the cortex of these mice. We identified three gene signatures: core transcriptional signature, unique signature for each wild-derived genetic background, and tau seeding-associated signature. Our data suggest that microglial response to tau seeds is elevated in CAST/EiJ and PWK/PhJ mice. Together, our study provides the first evidence that mouse genetic context influences the seeding of tau.

SUMMARY

Seeding of tau predates the phosphorylation and spreading of tau aggregates. Acri and colleagues report transcriptomic responses to tau and elevated tau seeds in wild-derived mice. This paper creates a rich resource by combining genetics, tau biosensor assays, and transcriptomics.

Deletion of the Alzheimer's disease risk gene Abi3 locus results in obesity and systemic metabolic disruption in mice

Alzheimer's disease (AD) genetics studies have identified a coding variant within ABI3 gene that increases the risk of developing AD. Recently, we demonstrated that deletion of the Abi3 gene locus dramatically exacerbates AD neuropathology in a transgenic mouse model of amyloidosis. In the course of this AD project, we unexpectedly found that deletion of the Abi3 gene locus resulted in a dramatic obese phenotype in non-transgenic mice. Here, we report our investigation into this serendipitous metabolic finding. Specifically, we demonstrate that mice with deletion of the Abi3 gene locus (Abi3-/- ) have dramatically increased body weight and body fat. Further, we determined that Abi3-/- mice have impaired energy expenditure. Additionally, we found that deletion of the Abi3 gene locus altered gene expression within the hypothalamus, particularly within immune-related pathways. Subsequent immunohistological analysis of the central nervous system (CNS) revealed that microglia number and area were decreased specifically within the mediobasal hypothalamus of Abi3-/- mice. Altogether, this investigation establishes the functional importance of the Abi3 gene locus in the regulation of systemic metabolism and maintenance of healthy body weight. While our previous findings indicated the importance of Abi3 in neurodegeneration, this study indicates that Abi3 related functions are also essential for metabolic regulation.

Manufacturing a chimpanzee adenovirus-vectored SARS-CoV-2 vaccine to meet global needs

Manufacturing has been the key factor limiting rollout of vaccination during the COVID-19 pandemic, requiring rapid development and large-scale implementation of novel manufacturing technologies. ChAdOx1 nCoV-19 (AZD1222, Vaxzevria) is an efficacious vaccine against SARS-CoV-2, based upon an adenovirus vector. We describe the development of a process for the production of this vaccine and others based upon the same platform, including novel features to facilitate very large-scale production. We discuss the process economics and the "distributed manufacturing" approach we have taken to provide the vaccine at globally-relevant scale and with international security of supply. Together, these approaches have enabled the largest viral vector manufacturing campaign to date, providing a substantial proportion of global COVID-19 vaccine supply at low cost.

Deletion of Abi3 gene locus exacerbates neuropathological features of Alzheimer's disease in a mouse model of Aβ amyloidosis

Recently, large-scale human genetics studies identified a rare coding variant in the ABI3 gene that is associated with an increased risk of Alzheimer’s disease (AD). However, pathways by which ABI3 contributes to the pathogenesis of AD are unknown. To address this question, we determined whether loss of ABI3 function affects pathological features of AD in the 5XFAD mouse model. We demonstrate that the deletion of Abi3 locus significantly increases amyloid β (Aβ) accumulation and decreases microglia clustering around the plaques. Furthermore, long-term potentiation is impaired in 5XFAD;Abi3 knockout (“Abi3−/−”) mice. Moreover, we identified marked changes in the proportion of microglia subpopulations in Abi3−/− mice using a single-cell RNA sequencing approach. Mechanistic studies demonstrate that Abi3 knockdown in microglia impairs migration and phagocytosis. Together, our study provides the first in vivo functional evidence that loss of ABI3 function may increase the risk of developing AD by affecting Aβ accumulation and neuroinflammation.

Molecular characterization of HEK293 cells as emerging versatile cell factories

HEK293 cell lines are used for the production of recombinant proteins, virus-like particles and viral vectors. Recent work has generated molecular (systems level) characterisation of HEK293 variants that has enabled re-engineering of the cells towards enhanced use for manufacture-scale production of recombinant biopharmaceuticals (assessment of 'safe harbours' for gene insertion, engineering of new variants for stable, amplifiable expression). In parallel, there have been notable advances in the bioprocessing conditions (suspension adaptation, development of defined serum-free media) that offer the potential for large-scale manufacture, a feature especially important in the drive to produce viral vectors at large-scale and at commercially viable costs for gene therapy. The combination of cell-based and bioprocess-based modification of existing HEK293 cell processes, frequently informed by understandings transferred from developments with Chinese hamster ovary cell lines, seems destined to place the HEK293 cell systems firmly as a critical platform for production of future biologically based therapeutics.

Tuning recombinant protein expression to match secretion capacity

Background

The secretion of recombinant disulfide-bond containing proteins into the periplasm of Gram-negative bacterial hosts, such as E. coli, has many advantages that can facilitate product isolation, quality and activity. However, the secretion machinery of E. coli has a limited capacity and can become overloaded, leading to cytoplasmic retention of product; which can negatively impact cell viability and biomass accumulation. Fine control over recombinant gene expression offers the potential to avoid this overload by matching expression levels to the host secretion capacity.

Results

Here we report the application of the RiboTite gene expression control system to achieve this by finely controlling cellular expression levels. The level of control afforded by this system allows cell viability to be maintained, permitting production of high-quality, active product with enhanced volumetric titres.

Conclusions

The methods and systems reported expand the tools available for the production of disulfide-bond containing proteins, including antibody fragments, in bacterial hosts.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-1047-z) contains supplementary material, which is available to authorized users.

Measuring depth of anaesthesia using changes in directional connectivity: a comparison with auditory middle latency response and estimated bispectral index during propofol anaesthesia

General anaesthesia is associated with changes in connectivity between different regions of the brain, the assessment of which has the potential to provide a novel marker of anaesthetic effect. We propose an index that quantifies the strength and direction of information flow in electroencephalographic signals collected across the scalp, assess its performance in discriminating 'wakefulness' from 'anaesthesia', and compare it with estimated bispectral index and the auditory middle latency response. We used a step-wise slow induction of anaesthesia in 10 patients to assess graded changes in electroencephalographic directional connectivity at propofol effect-site concentrations of 2 μg.ml^-1 , 3 μg.ml^-1 and 4 μg.ml^-1 . For each stable effect-site concentration, connectivity was estimated from multichannel electroencephalograms using directed coherence, together with middle latency response and estimated bispectral index. We used a linear support vector machine classifier to compare the performance of the different electroencephalographic features in discriminating wakefulness from anaesthesia. We found a significant reduction in the strength of long-range connectivity (interelectrode distance > 10 cm) (p < 0.008), and a reversal of information flow from markedly postero-frontal to fronto-posterior (p < 0.006) between wakefulness and a propofol effect-site concentration of 2 μg.ml^-1 . This then remained relatively constant as effect-site concentration increased, consistent with a step change in directed coherence with anaesthesia. This contrasted with the gradual change with increasing anaesthetic dose observed for estimated bispectral index and middle latency response. Directed coherence performed best in discriminating wakefulness from anaesthesia with an accuracy of 95%, indicating the potential of this new method (on its own or combined with others) for monitoring adequacy of anaesthesia.

Development of a generic β-lactamase screening system for improved signal peptides for periplasmic targeting of recombinant proteins in Escherichia coli

Targeting of recombinant proteins to the Escherichia coli periplasm is a desirable industrial processing tool to allow formation of disulphide bonds, aid folding and simplify recovery. Proteins are targeted across the inner membrane to the periplasm by an N-terminal signal peptide. The sequence of the signal peptide determines its functionality, but there is no method to predict signal peptide function for specific recombinant proteins, so multiple signal peptides must be screened for their ability to translocate each recombinant protein, limiting throughput. We present a screening system for optimising signal peptides for translocation of a single chain variable (scFv) antibody fragment employing TEM1 β-lactamase (Bla) as a C-terminal reporter of periplasmic localisation. The Pectobacterium carotovorum PelB signal peptide was selected as the starting point for a mutagenic screen. β-lactamase was fused to the C-terminal of scFv and β-lactamase activity was correlated against scFv translocation. Signal peptide libraries were generated and screened for β-lactamase activity, which correlated well to scFv::Bla production, although only some high activity clones had improved periplasmic translocation of scFv::Bla. Selected signal peptides were investigated in fed-batch fermentations for production and translocation of scFv::Bla and scFv without the Bla fusion. Improved signal peptides increased periplasmic scFv activity by ~40%.

Optimizing host cell physiology and stress avoidance for the production of recombinant human tumour necrosis factor α in Escherichia coli

As high-level recombinant protein production (RPP) exerts a massive stress on the production host, an extensive literature on RPP optimization focuses on separating the growth phase from RPP production once sufficient biomass has been obtained. The aim of the current investigation was to optimize the benefits of the relatively neglected alternative strategy to achieve high-level RPP during growth by minimizing stress on the host. High yields of the biopharmaceutical recombinant human tumour necrosis factor alpha (rhTNFα) were obtained by fed-batch fermentation relevant to industrial production based upon parameters that most severely affected RPP in preliminary laboratory scale batch cultures. Decreasing the inducer concentration and growth temperature, but increasing the production period, were far more effective for increasing RPP yields than changing the growth phase at which production was induced. High yields of up to 5 g l^-1 of rhTNFα were obtained with minimal plasmid loss, even in synthetic media that lack animal-derived components and are therefore fully compliant with regulatory requirements. Most of the product was soluble and biologically active. In summary, stress minimization was shown to be an effective way to optimize the production of rhTNFα. Data generated in shake-flask experiments allowed the design of intensified bioreactor cultures in which RPP and growth could be balanced, leading to higher yield of both rhTNFα and biomass than with previous fermentations. An additional benefit of this approach is avoidance of lysis during harvesting and downstream processing.

Directional connectivity in the EEG is able to discriminate wakefulness from NREM sleep

A reliable measure of consciousness is of great interest for various clinical applications including sleep studies and the assessment of depth of anaesthesia. A number of measures of consciousness based on the EEG have been proposed in the literature and tested in studies of dreamless sleep, general anaesthesia and disorders of consciousness. However, reliability has remained a persistent challenge. Despite considerable theoretical and experimental effort, the neural mechanisms underlying consciousness remain unclear, but connectivity between brain regions is thought to be disrupted, impairing information flow.

OBJECTIVE

The objective of the current work was to assess directional connectivity between brain regions using directed coherence and propose and assess an index that robustly reflects changes associated with non-REM sleep.

APPROACH

We tested the performance on polysomnographic recordings from ten healthy subjects and compared directed coherence (and derived features) with more established measures calculated from EEG spectra. We compared the performance of the different indexes to discriminate the level of consciousness at group and individual level.

MAIN RESULTS

At a group level all EEG measures could significantly discriminate NREM sleep from waking, but there was considerable individual variation. Across all individuals, normalized power, the strength of long-range connections and the direction of functional links strongly correlate with NREM sleep stages over the experimental timeline. At an individual level, of the EEG measures considered, the direction of functional links constitutes the most reliable index of the level of consciousness, highly correlating with the individual experimental time-line of sleep in all subjects.

SIGNIFICANCE

Directed coherence provides a promising new means of assessing level of consciousness, firmly based on current physiological understanding of consciousness.

Does the use of leucocyte depletion during cardiopulmonary bypass affect exhaled nitric oxide production?

Fifty patients undergoing elective coronary revascularisation were prospectively randomised to receive either a leucocyte-depleting or a control filter inserted into the arterial line of the cardiopulmonary bypass (CPB) circuit. The concentration of exhaled nitric oxide (NO) was measured 15 min before and 30 min after CPB using a real-time chemiluminescence analyser (Logan Research, Northampton, UK). The baseline rate of exhaled NO production was 2.14±0.83 ppb/s in the control group, and 2.58±0.53 ppb/s in leucocyte-depleted group ( p = 0.17). Following CPB, the mean rate of exhaled NO production in the control group had increased by 1.51±0.45 ppb/s to 3.65±0.81 ppb/s and in the leucocyte-depletion group had increased by 1.05±0.45 ppb/s to 3.64±0.62 ppb/s. The increase in exhaled NO production was significantly lower in the leucocyte depleted group ( p = 0.002), indicating that leucocyte depletion suppressed the increase in exhaled NO production seen following CPB.

Optimal Irrigation and Debridement of Infected Total Joint Implants with Chlorhexidine Gluconate

Previous study at our institution demonstrated that scrubbing a methicillin-resistant Staphylococcus aureus (MRSA)-coated titanium disk with chlorhexidine gluconate (CG) solution achieved superior biofilm eradication compared to alternative solutions. The current study aimed to identify the minimum CG concentration for effective bacteria eradication of an in vitro periprosthetic joint infection (PJI) model. MRSA colony-forming units (CFUs) were counted following simulated irrigation and debridement with varying CG solutions before and after a 24-hour reincubation period. Significant decrease was noted on all disks before reincubation. Postreincubation, significant decrease in CFUs was found in the 4% and 2% groups. This study demonstrated that I+D of an infected PJI model with 4% CG solution was effective at treating MRSA biofilm at concentrations as low as 2%.

Enhanced radial transport and energization of radiation belt electrons due to drift orbit bifurcations

[1]Relativistic electron intensities in Earth's outer radiation belt can vary by multiple orders of magnitude on the time scales ranging from minutes to days. One fundamental process contributing to dynamic variability of radiation belt intensities is the radial transport of relativistic electrons across their drift shells. In this paper we analyze the properties of three-dimensional radial transport in a global magnetic field model driven by variations in the solar wind dynamic pressure. We use a test particle approach which captures anomalous effects such as drift orbit bifurcations. We show that the bifurcations lead to an order of magnitude increase in radial transport rates and enhance the energization at large equatorial pitch angles. Even at quiet time fluctuations in dynamic pressure, radial transport at large pitch angles exhibits strong deviations from the diffusion approximation. The radial transport rates are much lower at small pitch angle values which results in a better agreement with the diffusion approximation.

Ambulatory cell phone injuries in the United States: an emerging national concern

BACKGROUND

Over the past 15 years, the use of cell phones has increased 8-fold in the United States. Cell phone use has been shown to increase crash risks for drivers, but no systematic analyses have described injuries related to ambulatory cell phone use.

OBJECTIVE

The purpose of this study is to describe and quantitate injuries and deaths among persons using cell phones while walking.

METHODS

We searched the National Electronic Injury Surveillance System (NEISS) for emergency department (ED) reports of injuries related to phone use. The cases that returned were screened initially using words that would eliminate cases unlikely to be related to cell phone use and walking, possibly linked to distraction. The resulting cases were randomized and evaluated for consistency with predetermined case definitions by two authors blinded to the dates of the incidents. Cases that were disagreed upon were evaluated in a second screening by both authors for final case determination. National ED visit rates were estimated based on NEISS sampling methods. Annual variations were analyzed using linear regression with a restricted maximum likelihood approach.

RESULTS

Our screening process identified 5,754 possible cases that occurred between 2000 and 2011, and 310 were agreed on as cases of cell-phone-induced distraction. The majority of the patients were female (68%) and 40 years of age or younger (54%). The primary mechanism of injury was a fall (72%), and most patients were treated and released from the ED (85%). No patients died from their injuries while they were in the ED. Linear modeling by year revealed a statistically significant increase in distraction injury rates over the years of study (p<0.001 for trend).

CONCLUSIONS

The number of ED visits by ambulatory persons injured while being distracted by cell phone use has been increasing. More research is needed to determine the risks associated with walking and talking on a cell phone and to develop strategies for intervention.

PRACTICAL APPLICATIONS

Cell phone use continues to increase both at home and outdoor environments. The use of smart phones, with their more enticing features, increases the likelihood of distraction-induced injuries even more. Manufacturers should consider the addition of tools or applications on smart phones to remind users to remain alert to outside auditory stimuli that herald external hazards and to encourage them to not use these devices while engaged in other activities.

Antivenoms

The first advance on crude filtered immune serum or plasma for treating systemically envenomed bite victims was the use of IgG (predominantly equine) precipitated by salt treatment. This was followed by the development of F(ab')(2) antivenoms, prepared using pepsin digestion to remove both the highly reactive and nonspecific Fc part of the IgG molecule and also other non-antibody proteins from the material. Within normal limitations, both monospecific (raised against the venom of a single species) and polyspecific (raised against a mixture of venoms of different species) F(ab')(2) antivenoms have proved to be generally effective. Many preparations are poor for a wide range of reasons often not related to the method of preparation. The main problem associated with them is the high reaction rate in patients caused by complement-mediated anaphylactic reactions. The most significant recent development in immunotherapy has been the production of ovine Fab antivenoms prepared by replacing pepsin digestion with papain digestion. Theoretically, these possess advantages over F(ab')(2) antivenoms, such as a greater volume of distribution and more rapid kinetics. A major disadvantage of Fab antivenoms is, however, their shorter clearance time, which may result in inadequate blood antivenom concentrations for neutralising venom entering the system late from a venom depot at the bite site. Affinity purification of both Fab and F(ab')(2) antivenoms also results in a major increase in specific activity when compared with the original serum source, but this adds greatly to the cost of production, rendering its use prohibitive in the rural tropics where bites and stings are a major problem. The use of sheep as opposed to horses for immunisation also results in a cheaper product, due to the lower cost of animal maintenance; theoretically, sheep preparations should also be safer, causing fewer sensitivity reactions, due to the nature of ovine as opposed to equine protein. Additionally, it is a great advantage in the rural tropics to have a lyophilised, as opposed to a liquid, antivenom because of the longer shelf-life of the former at ambient tropical temperatures. However, lyophilisation does add considerably to the cost of production, involves additional testing and has also in the past been reported to result in some decrease in neutralising potency. There may well be a case for the development of a combined ovine Fab/F(ab')(2) antivenom which combines the advantages of each product. Alternatives to conventional antivenoms should also be explored in the future.

The use of dermabond® as an adjunct to wound closure after total knee arthroplasty: examining immediate post-operative wound drainage

Wound drainage after total knee arthroplasty (TKA) can be detrimental to surgical outcome. This IRB-approved randomized, prospective, blinded study examined the use of Dermabond® as an adjunct to wound closure after TKA. We proposed that Dermabond® supplementation to wound closure would result in a significant decrease in wound drainage after TKA. After standardized closure, patients were randomized into experimental or control groups with the experimental group receiving Dermabond® supplementation. Standardized dressings were evaluated postoperatively and drainage units were compared using a Mann-Whitney U Test. The median drainage for the Dermabond group (153) was lower than the drainage for the control group (657) at a statistically significant level (P<0.001).

Phase II trial of oral 1,25-dihydroxyvitamin D (calcitriol) in hormone refractory prostate cancer

Epidemiologic and experimental data support a role for 1,25-dihydroxyvitamin D(3) in the growth regulation of prostate cancer. We conducted a phase II clinical trial evaluating calcitriol (1,25(OH)(2)D(3)) in patients with hormone refractory prostate cancer. We enrolled 14 patients in this study. 1,25(OH)(2)D(3) was initiated at a daily oral dose of 0.5 μg and escalated to 1.5 μg daily. No objective responses were observed. However, in two patients decreases of 25% and 45% in prostate specific antigen levels were seen. Hypercalcemia was the predominant toxicity. We conclude that 1,25(OH)(2)D(3) given in this manner is inactive in advanced prostate cancer. Dose escalation of oral 1,25(OH)(2)D(3) is limited by hypercalcemia.

Phase II study of first-line sagopilone plus prednisone in patients with castration-resistant prostate cancer: a phase II study of the Department of Defense Prostate Cancer Clinical Trials Consortium

BACKGROUND

Preclinical studies in prostate cancer (PC) models demonstrated the anti-tumour activity of the first fully synthetic epothilone, sagopilone. This is the first study to investigate the activity and safety of sagopilone in patients with metastatic castration-resistant PC (CRPC).

METHODS

Chemotherapy-naïve patients with metastatic CRPC received sagopilone (one cycle: 16 mg m(-2) intravenously over 3 h q3w) plus prednisone (5 mg twice daily). The primary efficacy evaluation was prostate-specific antigen (PSA) response rate (≥50% PSA reduction confirmed ≥28 days apart). According to the Simon two-stage design, ≥3 PSA responders were necessary within the first 13 evaluable patients for recruitment to continue until 46 evaluable patients were available.

RESULTS

In all, 53 patients received ≥2 study medication cycles, with high compliance. Mean individual dose was 15.1±1.4 mg m(-2) during initial six cycles, mean dose intensity 94±9%. The confirmed PSA response rate was 37%. Median overall progression-free survival was 6.4 months. The most commonly reported adverse events (>10% of patients) were peripheral neuropathy (94.3%), fatigue (54.7%) and pain in the extremities (47.2%). Sagopilone was associated with very little haematological toxicity.

CONCLUSION

This study shows that first-line sagopilone has noteworthy anti-tumour activity and a clinically significant level of neuropathy for patients with metastatic chemotherapy-naïve CRPC.

On the mechanism of carbon nanotube formation: the role of the catalyst

This work examines the recent developments in non-traditional catalyst-assisted chemical vapour deposition of carbon nanotubes (CNTs) with a view to determining the essential role of the catalyst in nanotube growth. A brief overview of the techniques reliant on the structural reorganization of carbon to form CNTs is provided. Additionally, CNT synthesis methods based upon ceramic, noble metal, and semiconducting nanoparticle catalysts are presented. Experimental evidence is provided for CNT growth using noble metal and semiconducting nanoparticle catalysts. A model for CNT growth consistent with the experimental results is proposed, in which the structural reorganization of carbon to form CNTs is paramount.

Quality measure study: progress in reducing the door-to-balloon time in patients with ST-segment elevation myocardial infarction

BACKGROUND

Reperfusion therapy improves both mortality and morbidity in patients with ST-elevation myocardial infarction (STEMI). Timeliness of such reperfusion is an important factor in improving patient survival. For percutaneous coronary intervention (PCI), the American College of Cardiology has recommended a goal of <90 minutes from initial hospital contact to first balloon inflation.

METHODS

The authors retrospectively reviewed 131 patients with a diagnosis of STEMI seen at a PCI capable hospital between January, 2006 and September, 2008, a period of time before and after implementation of a protocol aimed at reducing door-to-balloon time. Sixty-one percent of study population was Asian or Pacific Islander. This protocol was largely based on the identification by Bradley et al. of factors whose modification could shorten this time interval.

RESULTS

Time to reperfusion was compared between groups before (n=57), and after (n=58) protocol implementation. Median door-to-balloon time for the former group was 133 minutes, interquartile range (IQRs), (25th, 75th percentile; 104.5, 147), and for the latter group 67 minutes, IQRs (56, 80) respectively (p<0.001). Prior to implementation of the protocol, a door-to-balloon time of <90 minutes was achieved in 17% of cases. By the third quarter of 2008, this goal was being met in 100%.

CONCLUSION

This observational study provides support for the use of the strategies described as a key for reduction in door-to-balloon time.

alpha-Glucuronidase and Other Hemicellulase Activities of Fibrobacter succinogenes S85 Grown on Crystalline Cellulose or Ball-Milled Barley Straw

Fibrobacter succinogenes produces an alpha-glucuronidase which cleaves 4-O-methyl-alpha-d-glucuronic acid from birch wood 4-O-methyl-alpha-d-glucuronoxylan. Very low levels of alpha-glucuronidase activity were detected in extracellular enzyme preparations of F. succinogenes on birch wood xylan substrate. The release of 4-O-methyl-alpha-d-glucuronic acid was enhanced when the birch wood xylan substrate was predigested by either a purified Schizophyllum commune xylanase or a cloned F. succinogenes S85 xylanase. These data suggest that the alpha-glucuronidase is unable to cleave 4-O-methyl-alpha-d-glucuronic acid from intact xylan but can act on unique low-molecular-weight glucuronoxylan fragments created by the cloned F. succinogenes xylanase. The cloned xylanase presumably must account for a small proportion of the indigenous xylanase activity of F. succinogenes cultures, since this xylanase source does not support high glucuronidase activity. The alpha-glucuronidase and associated hemicellulolytic enzymes exhibited higher activities in culture fluid from cells grown on ball-milled barley straw than in that of cellulose-grown cells. The profile of xylanases separated by isoelectric focusing (zymogram) of culture filtrate from cells grown on barley straw was more complex than that of culture filtrates from cells grown on cellulose. These data demonstrate that F. succinogenes produces an alpha-glucuronidase with an exacting substrate specificity which enables extensive cleavage of glucuronic acid residues from xylan as a consequence of synergistic xylanase action.

Trauma activations and their effects on non-trauma patients

BACKGROUND

Trauma patients consume many resources in the emergency department (ED), but what effect their care may have upon other patients seeking care is unclear.

OBJECTIVE

We sought to determine whether the presentation of trauma patients to the ED diverts staff and resources away from non-trauma patients. We hypothesized that the admission of trauma patients to the ED would result in longer times to physician evaluation and completion of laboratory and imaging studies, as well as a longer length of stay in the ED.

METHODS

This retrospective study reviewed and compared the charts of two groups of non-trauma ED patients. The group affected by trauma arrived up to 30 min after a trauma activation. The group unaffected by trauma arrived >3 h before or 3 h after a trauma activation. Times from arrival to initial MD evaluation, X-ray study, and computed tomography (CT) scan were documented. Median times from order to completion of laboratory results and imaging were compared, as well as total ED lengths of stay (LOS).

RESULTS

Median time from arrival to MD evaluation for patients affected by a trauma activation was almost twice as long as for unaffected patients (42 vs. 23 min, respectively; p < 0.001). Times from arrival to X-ray study, CT scan order, and laboratory results were all significantly greater for patients affected by a trauma activation (p < 0.001). For patients who required admission to the hospital, the affected group had a median LOS that was increased by 16 min (224 vs. 208 min, respectively) when compared to unaffected patients (p = 0.04).

CONCLUSION

In the setting studied, the arrival of a trauma patient delayed physician evaluation and diagnostic testing. It only modestly increased the ED LOS for patients needing hospital admission.

Auditory evoked potentials for monitoring during anaesthesia: a study of data quality

The auditory evoked potential termed the middle latency response (MLR) has been suggested as an indicator of adequacy of anaesthesia during surgery. However, the response is small and must be extracted from high levels of background noise. A key consideration in using the MLR for clinical monitoring is whether data quality is sufficient to detect small changes. The aim of this study was to investigate the quality of the MLR recorded during anaesthesia, as a rigorous analysis of data quality is lacking in many studies. MLR recordings from patients sedated in intensive care after cardiac surgery were compared to recordings from a reference group of young volunteers with normal hearing. Data quality was measured with the F(sp) parameter. A bootstrap analysis was used to measure statistical response presence and to detect within-subject changes during clinical anaesthesia. Noise levels were high in the normative group probably due to myogenic and EEG activity. With 5 Hz click stimulation, MLR presence in the normative group was below 30%. Response presence improved using stimulation paradigms with chirps or maximum length sequences and reached 100% with a combination of maximum length sequences and chirps. F(sp) values generally improved during anaesthesia as noise levels reduced and MLR presence was 100% for MLS click stimulation. Changes in the MLR amplitude with propofol infusion rate were small. Some within-subject changes in MLR amplitude were detected using the bootstrap analysis, but 100% detection was not possible.

CONCLUSION

Obtaining good quality MLR data in awake subjects is challenging. Data quality improves during clinical anaesthesia and with advanced stimulation methods, but reliable detection of changes in the MLR for clinical monitoring remains a challenge.

The effect of mannitol on renal function after cardiopulmonary bypass in patients with established renal dysfunction

The usefulness of mannitol in the priming fluid for cardiopulmonary bypass is uncertain in patients with normal renal function, and has not been studied in patients with established renal dysfunction. We studied 50 patients with serum creatinine between 130 and 250 micromol.l(-1) having cardiac surgery. Patients were randomised to receive mannitol 0.5 g.kg(-1), or an equivalent volume of Hartmann's solution, in the bypass prime. There were no differences between the groups in plasma creatinine or change in creatinine from baseline, urine output, or fluid balance over the first three postoperative days. We conclude that mannitol has no effect on routine measures of renal function during cardiac surgery in patients with established renal dysfunction.

Endovascular treatment of carotid and vertebral pseudoaneurysms with covered stents

BACKGROUND AND PURPOSE

Endovascular treatment of vascular lesions has revolutionized the treatment of arterial pseudoaneurysms. We describe our experience in treating carotid or vertebral pseudoaneurysms with covered stents.

MATERIALS AND METHODS

Ten patients with carotid or vertebral pseudoaneurysms treated with self-expanding or balloon-expandable covered stents were retrospectively reviewed after we obtained institutional review board approval. Distal protection devices were not used. All patients except 1 received anticoagulation therapy. Antiplatelet therapy was used in 8 of 10 patients. Follow-up was performed from 5 days to 25 months. Patients were followed with digital subtraction angiography, CT angiography (CTA), and/or sonography (US).

RESULTS

Pseudoaneurysm occlusion was obtained in all 10 patients. None of the pseudoaneurysms recanalized during the follow-up period. One patient had a distal embolization to the middle cerebral artery despite anticoagulation and antiplatelet therapy. One patient who did not receive any anticoagulation had stent occlusion at 4.5 months. Anticoagulation was stopped after 6 months in 2 patients with persistent stent patency and no neurologic complications for >1 year. Both US and CTA were useful for extracranial stent surveillance. CTA was helpful for intracranial stent surveillance.

CONCLUSION

In this small series, the use of covered stents allowed safe and effective treatment of pseudoaneurysms occurring in the cervical and cephalic segments of the carotid and vertebral arteries.

Survival impact of lymph node dissection in endometrial adenocarcinoma: a surveillance, epidemiology, and end results analysis

The therapeutic benefit of lymph node dissection (LND) in women with endometrial cancer remains controversial. The purpose of this study is to analyze the impact of LND on survival. Data were obtained from the Surveillance, Epidemiology, and End Results program of the US National Cancer Institute for the years 1988–2003. Women with adenocarcinoma of the endometrium who underwent surgery as primary management of their disease were eligible. Multivariate analyses of pertinent variables were performed for the end points of overall survival and cause-specific survival. Women included in the analysis were 42,184. The average frequency of LND was 31%, 40%, 47%, and 53%, for the years 1988–1991, 1992–1995, 1996–1999, and 2000–2003, respectively (P< 0.0001). On multivariate analysis, presence of LND was associated with overall and uterine-specific survival benefits with hazard ratios (HR) of 0.81 (P< 0.0001) and 0.78 (P< 0.0001) and removal of greater than 11 lymph nodes (LN) associated with a HR of 0.74 (P< 0.0001) and 0.69 (P< 0.0001), respectively. Further multivariate analyses demonstrated greater than 11 LN to associate with all other cause-specific and cardiac-specific survival benefits, with HR of 0.77 (P< 0.0001) and 0.82 (P= 0.0062), respectively. We conclude that the presence of LND and increased number of nodes dissected predicted for improved overall and uterine-specific survival in women with adenocarcinoma of the endometrium. Improved cause-specific survival was most pronounced for greater than 11 nodes removed and stage II or higher disease. The improvement in noncancer-related mortality with LND predicted by this data suggests the presence of inherit biases, and the need for caution in analyzing retrospective data.

Cortical edema in moderate fluid percussion brain injury is attenuated by vagus nerve stimulation

Development of cerebral edema (intracellular and/or extracellular water accumulation) following traumatic brain injury contributes to mortality and morbidity that accompanies brain injury. Chronic intermittent vagus nerve stimulation (VNS) initiated at either 2 h or 24 h (VNS: 30 s train of 0.5 mA, 20 Hz, biphasic pulses every 30 min) following traumatic brain injury enhances recovery of motor and cognitive function in rats in the weeks following brain injury; however, the mechanisms of facilitated recovery are unknown. The present study examines the effects of VNS on development of acute cerebral edema following unilateral fluid percussion brain injury (FPI) in rats, concomitant with assessment of their behavioral recovery. Two hours following FPI, VNS was initiated. Behavioral testing, using both beam walk and locomotor placing tasks, was conducted at 1 and 2 days following FPI. Edema was measured 48 h post-FPI by the customary method of region-specific brain weights before and after complete dehydration. Results of this study replicated that VNS initiated at 2 h after FPI: 1) effectively facilitated the recovery of vestibulomotor function at 2 days after FPI assessed by beam walk performance (P<0.01); and 2) tended to improve locomotor placing performance at the same time point (P=0.18). Most interestingly, results of this study showed that development of edema within the cerebral cortex ipsilateral to FPI was significantly attenuated at 48 h in FPI rats receiving VNS compared with non-VNS FPI rats (P<0.04). Finally, a correlation analysis between beam walk performance and cerebral edema following FPI revealed a significant inverse correlation between behavior performance and cerebral edema. Together, these results suggest that VNS facilitation of motor recovery following experimental brain injury in rats is associated with VNS-mediated attenuation of cerebral edema.

Depth-mediated reversal of the effects of climate change on long-term growth rates of exploited marine fish

The oceanographic consequences of climate change are increasingly well documented, but the biological impacts of this change on marine species much less so, in large part because of few long-term data sets. Using otolith analysis, we reconstructed historical changes in annual growth rates for the juveniles of eight long-lived fish species in the southwest Pacific, from as early as 1861. Six of the eight species show significant changes in growth rates during the last century, with the pattern differing systematically with depth. Increasing temperatures near the ocean surface correlate with increasing growth rates by species found in depths <250 m, whereas growth rates of deep-water (>1,000 m) species have declined substantially during the last century, which correlates with evidence of long-term cooling at these depths. The observations suggest that global climate change has enhanced some elements of productivity of the shallow-water stocks but also has reduced the productivity, and possibly the resilience, of the already slow-growing deep-water species.

Syntaxin 16 and syntaxin 5 are required for efficient retrograde transport of several exogenous and endogenous cargo proteins

Retrograde transport allows proteins and lipids to leave the endocytic pathway to reach other intracellular compartments, such as trans-Golgi network (TGN)/Golgi membranes, the endoplasmic reticulum and, in some instances, the cytosol. Here, we have used RNA interference against the SNARE proteins syntaxin 5 and syntaxin 16, combined with recently developed quantitative trafficking assays, morphological approaches and cell intoxication analysis to show that these SNARE proteins are not only required for efficient retrograde transport of Shiga toxin, but also for that of an endogenous cargo protein - the mannose 6-phosphate receptor - and for the productive trafficking into cells of cholera toxin and ricin. We have found that the function of syntaxin 16 was specifically required for, and restricted to, the retrograde pathway. Strikingly, syntaxin 5 RNA interference protected cells particularly strongly against Shiga toxin. Since our trafficking analysis showed that apart from inhibiting retrograde endosome-to-TGN transport, the silencing of syntaxin 5 had no additional effect on Shiga toxin endocytosis or trafficking from TGN/Golgi membranes to the endoplasmic reticulum, we hypothesize that syntaxin 5 also has trafficking-independent functions. In summary, our data demonstrate that several cellular and exogenous cargo proteins use elements of the same SNARE machinery for efficient retrograde transport between early/recycling endosomes and TGN/Golgi membranes.

Dynamic interplay between the neutral glycosphingolipid CD77/Gb3 and the therapeutic antibody target CD20 within the lipid bilayer of model B lymphoma cells

The centroblast-specific differentiation marker CD77 (Gb(3)), is the receptor for Shiga-like toxin (SLT). The dynamic relationship between Gb(3)/CD77 and key B-cell membrane proteins was studied in Burkitt's lymphoma cells with a focus on CD20. Engagement of Gb(3)/CD77 with SLT-B reduced the amount of CD20 and CXCR4 available, but levels of BCR, MHC Class II, CD21, CD27 and CD54 remained unchanged. Cholesterol depletion promoted a decrease in the number of sites accessed by CD20, CXCR4 and Gb(3)/CD77 antibodies. Constitutive localisation of Gb(3)/CD77 to lipid rafts was unperturbed by either SLT-B binding or cholesterol depletion, whereas the opposite was true for CD20. The effects were specific to SLT-B, highlighted by the inability of cholera toxin B-subunit to alter CD20 availability. Thus, the binding of Gb(3)/CD77 by its cognate ligand transmits information within the lipid bilayer of model lymphoma cells to impact the behaviour of selective proteins, most notably CD20, via a mechanism influenced by the level of cholesterol within the membrane.

Ricin: current understanding and prospects for an antiricin vaccine

Ricin is a potent cytotoxin that can be rapidly internalized into mammalian cells leading to cell death. The ease in obtaining the toxin and its deadly nature combine to implicate ricin as a convenient agent for bioterrorism. Research into the mechanism of toxicity, as well as strategies for treatment and protection from the toxin has been widely undertaken for a number of years. This article reviews the current understanding of the mechanism of action of the toxin, the clinical effects of ricin intoxication and how these relate to current and continuing prospects for vaccine development.

Stimulation of pneumovirus-specific CD8+ T-cells using a non-toxic recombinant ricin delivery system

Internalisation of the plant toxin ricin occurs by retrograde transport which delivers the toxin to the ER where it intersects with the MHC class I system for peptide antigen display. Here, we describe the generation of an inactivated, non-toxic, ricin molecule fused to a peptide which elicits a CD8+ T-cell response in mice directed against pneumonia virus of mice, a pneumovirus related to human respiratory syncytial virus. The ricin fusion elicited a significant T-cell response when delivered by intraperitoneal inoculation in the absence of adjuvent. Challenge experiments showed that the T-cell response resulting from inoculation with the ricin-peptide fusion molecule delayed the onset of virus-induced disease.

Gas phase characterization of the noncovalent quaternary structure of cholera toxin and the cholera toxin B subunit pentamer

Cholera toxin (CTx) is an AB5 cytotonic protein that has medical relevance in cholera and as a novel mucosal adjuvant. Here, we report an analysis of the noncovalent homopentameric complex of CTx B chain (CTx B5) using electrospray ionization triple quadrupole mass spectrometry and tandem mass spectrometry and the analysis of the noncovalent hexameric holotoxin usingelectrospray ionization time-of-flight mass spectrometry over a range of pH values that correlate with those encountered by this toxin after cellular uptake. We show that noncovalent interactions within the toxin assemblies were maintained under both acidic and neutral conditions in the gas phase. However, unlike the related Escherichia coli Shiga-like toxin B5 pentamer (SLTx B), the CTx B5 pentamer was stable at low pH, indicating that additional interactions must be present within the latter. Structural comparison of the CTx B monomer interface reveals an additional alpha-helix that is absent in the SLTx B monomer. In silico energy calculations support interactions between this helix and the adjacent monomer. These data provide insight into the apparent stabilization of CTx B relative to SLTx B.

Retrograde transport pathways utilised by viruses and protein toxins

A model has been presented for retrograde transport of certain toxins and viruses from the cell surface to the ER that suggests an obligatory interaction with a glycolipid receptor at the cell surface. Here we review studies on the ER trafficking cholera toxin, Shiga and Shiga-like toxins, Pseudomonas exotoxin A and ricin, and compare the retrograde routes followed by these protein toxins to those of the ER trafficking SV40 and polyoma viruses. We conclude that there is in fact no obligatory requirement for a glycolipid receptor, nor even with a protein receptor in a lipid-rich environment. Emerging data suggests instead that there is no common pathway utilised for retrograde transport by all of these pathogens, the choice of route being determined by the particular receptor utilised.

Internalized Pseudomonas exotoxin A can exploit multiple pathways to reach the endoplasmic reticulum

Receptor-mediated internalization to the endoplasmic reticulum (ER) and subsequent retro-translocation to the cytosol are essential sequential processes required for the intoxication of mammalian cells by Pseudomonas exotoxin A (PEx). The toxin binds the alpha2-macroglobulin receptor/low-density lipoprotein receptor-related protein. Here, we show that in HeLa cells, PEx recruits a proportion of this receptor to detergent-resistant microdomains (DRMs). Uptake of receptor-bound PEx involves transport steps both directly from early endosomes to the trans-Golgi network (TGN) independently of Rab9 function and from late endosomes to the TGN in a Rab9-dependent manner. Furthermore, treatments that simultaneously perturb both Arf1-dependent and Rab6-dependent retrograde pathways show that PEx can use multiple routes to reach the ER. The Rab6-dependent route has only been described previously for cargo with lipid-sorting signals. These findings suggest that partial localization of PEx within DRM permits a choice of trafficking routes consistent with a model that DRM-associated toxins reach the ER on a lipid-dependent sorting pathway whilst non-DRM-associated PEx exploits the previously characterized KDEL receptor-mediated uptake pathway. Thus, unexpectedly, an ER-directed toxin with a proteinaceous receptor shows promiscuity in its intracellular trafficking pathways, exploiting routes controlled by both lipid- and protein-sorting signals.

The association of Shiga-like toxin with detergent-resistant membranes is modulated by glucosylceramide and is an essential requirement in the endoplasmic reticulum for a cytotoxic effect

Receptor-mediated internalization to the endoplasmic reticulum (ER) and subsequent retro-translocation to the cytosol are essential sequential processes required for the productive intoxication of susceptible mammalian cells by Shiga-like toxin-1 (SLTx). Recently, it has been proposed that the observed association of certain ER-directed toxins and viruses with detergent-resistant membranes (DRM) may provide a general mechanism for their retrograde transport to endoplasmic reticulum (ER). Here, we show that DRM recruitment of SLTx bound to its globotriosylceramide (Gb(3)) receptor is mediated by the availability of other glycosphingolipids. Reduction in glucosylceramide (GlcCer) levels led to complete protection against SLTx and a reduced cell surface association of bound toxin with DRM. This reduction still allowed efficient binding and transport of the toxin to the ER. However, toxin sequestration within DRM of the ER was abolished under reduced GlcCer conditions, suggesting that an association of toxin with lipid microdomains or rafts in the ER (where these are defined by detergent insolubility) is essential for a later step leading to or involving retro-translocation of SLTx across the ER membrane. In support of this, we show that a number of ER residents, proteins intimately involved in the process of ER dislocation of misfolded proteins, are present in DRM.

Noncovalent Shiga-like Toxin Assemblies: Characterization by Means of Mass Spectrometry and Tandem Mass Spectrometry

Shiga-like toxin 1 (SLTx), produced by enterohemorrhagic strains of Escherichia coli (EHEC), belongs to a family of structurally and functionally related AB(5) protein toxins that are associated with human disease. EHEC infection often gives rise to hemolytic colitis, while toxin-induced kidney damage is one of the major causes of hemolytic uremic syndrome (HUS) and acute renal failure in children. As such, an understanding and analysis of the noncovalent interactions that maintain the quaternary structure of this toxin are fundamentally important since such interactions have significant biochemical and medical implications. This paper reports on the analysis of the noncovalent homopentameric complex of Shiga-like toxin B chain (SLTx-B(5)) using electrospray ionization (ESI) triple-quadrupole (QqQ) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) and the analysis of the noncovalent hexameric holotoxin (SLTx-AB(5)) using ESI time-of-flight (TOF) MS. The triple-quadrupole analysis revealed highly charged monomer ions dissociate from the multiprotein complex to form dimer, trimer, and tetramer product ions, which were also seen to further dissociate. The ESI-TOFMS analysis of SLTx-AB(5) revealed the complex remained intact and was observed in the gas phase over a range of pHs. Theses findings demonstrate that the gas-phase structure observed for both the holotoxin and the isoloated B chains correlates well with the structures reported to exist in the solution phase for these proteins. Such analysis provides a rapid screening technique for assessing the noncovalent structure of this family of proteins and other structurally related toxins.

Dissolved oxygen saturation controls PAH biodegradation in freshwater estuary sediments

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in terrestrial and aquatic environments and can represent a significant constituent of the carbon pool in coastal sediments. We report here the results of an 18-month seasonal study of PAH biodegradation and heterotrophic bacterial production and their controlling biogeochemical factors from 186 sediment samples taken in a tidally influenced freshwater estuary. For each sampling event, measurements were averaged from 25-45 stations covering approximately 250 km(2). There was a clear relationship between bacterial production and ambient temperature, but none between production and bottom water dissolved oxygen (DO) % saturation or PAH concentrations. In contrast with other studies, we found no effect of temperature on the biodegradation of naphthalene, phenanthrene, or fluoranthene. PAH mineralization correlated with bottom water DO saturation above 70% (r(2) > 0.99). These results suggest that the proportional utilization of PAH carbon to natural organic carbon is as much as three orders of magnitude higher during cooler months, when water temperatures are lower and DO % saturation is higher. Infusion of cooler, well-oxygenated water to the water column overlying contaminated sediments during the summer months may stimulate PAH metabolism preferentially over non-PAH organic matter.

Ricin: the endoplasmic reticulum connection

Ricin is a potent, plant-derived, ribosome inactivating protein. To target ribosomes in the mammalian cytosol, ricin must firstly negotiate the endomembrane system of the cell to reach the endoplasmic reticulum. Here, the toxin is reduced and the catalytic A chain is recognised by ER components that facilitate its membrane translocation to the cytosol. To be toxic, ricin A chain must then avoid degradation, a conundrum made more tricky in that ubiquitination and proteasomal degradation are normally tightly coupled to the translocation process. This mini-review summarises current understanding of these events.

Does leucocyte depletion during cardiopulmonary bypass improve oxygenation indices in patients with mild lung dysfunction?

BACKGROUND

Leucocyte-depleting arterial line filters have not dramatically improved lung function after cardiopulmonary bypass (CPB), but patients with pre-existing lung dysfunction may benefit from their use.

METHODS

We randomized 32 patients with mild lung dysfunction having elective first-time coronary revascularization to either a leucocyte depleting or a standard 40-mm arterial line filter during CPB. The alveolar arterial oxygenation index was calculated before and 5 min after CPB, then at 1, 2, 4, 8, and 18 h after surgery. Time to extubation on the ITU was recorded. Preoperative, immediate postoperative, and 24 h postoperative chest x-rays were scored for extravascular lung water.

RESULTS

Postoperative alveolar-arterial oxygenation indices were better in the patients who received leucocyte depletion during CPB (1.65+/-0.96 in the study group vs 2.90+/-1.72 in the control group, P<0.05). The duration of postoperative mechanical ventilation was less in the leucocyte-depleted group (4.8+/-2.1 vs 8.3+/-4.7 h in the control group, P<0.05). The extravascular lung water scores immediately postoperatively were 13.0+/-8.6 in the study group vs 19.6+/-10.8 in the control group (P=0.04), and at 24 h postoperatively, 9.7+/-7.7 vs 15.2+/-9.9 for controls.

CONCLUSIONS

For patients with mild lung dysfunction, a leucocyte-depleting arterial line filter improves postoperative oxygenation, reduces extravascular lung water accumulation, and reduces time on artificial ventilator after CPB. There may be an economic argument for the routine use of leucocyte-depleting filters for every patient during CPB.