Legacy metal contamination is reflected in the fish gut microbiome in an urbanised estuary

Estuaries are critical habitats subject to a range of stressors requiring effective management. Microbes are gaining recognition as effective environmental indicators, however, the response of host associated communities to stressors remains poorly understood. We examined microbial communities from seawater, sediments and the estuarine fish Pelates sexlineatus, in Australia\u27s largest urbanised estuary, and hypothesised that anthropogenic contamination would be reflected in the microbiology of these sample types. The human faecal markers Lachno3 and HF183 were not detected, indicating negligible influence of sewage, but a gradient in copy numbers of the class 1 integron (intI-1), which is often used as a marker for anthropogenic contamination, was observed in sediments and positively correlated with metal concentrations. While seawater communities were not strongly driven by metal contamination, shifts in the diversity and composition of the fish gut microbiome were observed, with statistical links to levels of metal contamination (F2, 21 = 1.536, p \u3c 0.01). Within the fish gut microbiome, we further report increased relative abundance of amplicon sequence variants (ASVs; single inferred DNA sequences obtained in sequencing) identified as metal resistant and potentially pathogenic genera, as well as those that may have roles in inflammation. These results demonstrate that microbial communities from distinct habitats within estuarine systems have unique response to stressors, and alterations of the fish gut microbiome may have implications for the adaptation of estuarine fish to legacy metal contamination

Depth-resolved measurement of the Meissner screening profile in a niobium thin film from spin-lattice relaxation of the implanted β\beta-emitter 8^{8}Li

We report measurements of the Meissner screening profile in a Nb(300 nm)/Al$_{2}$O$_{3}$ thin film using $^{8}$Li $\beta$-detected nuclear magnetic resonance ($\beta$-NMR). The NMR probe $^{8}$Li was ion-implanted into the Nb film at energies $\leq$ 20 keV, corresponding to mean stopping depths comparable to Nb's magnetic penetration depth $\lambda$. $^{8}$Li's strong dipole-dipole coupling with the host $^{93}$Nb nuclei provided a "cross-relaxation" channel that dominated in low magnetic fields, which conferred indirect sensitivity to the local magnetic field via the spin-lattice relaxation (SLR) rate $1/T_{1}$. From a fit of the $1/T_{1}$ data to a model accounting for its dependence on temperature, magnetic field, and $^{8}$Li$^{+}$ implantation energy, we obtained a magnetic penetration depth $\lambda_{0}$ = 51.5(22) nm, consistent with a relatively short carrier mean-free-path $\ell$ = 18.7(29) nm typical of similarly prepared Nb films. The results presented here constitute an important step towards using $^{8}$Li $\beta$-NMR to characterize bulk Nb samples with engineered surfaces, which are often used in the fabrication of particle accelerators.Comment: 16 pages, 4 figure

The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth

Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50=1.1±0.1μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2- consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed

Procalcitonin as a potent marker of bacterial infection in febrile Afro-Caribbean patients at the emergency department

Procalcitonin (PCT) has been shown to be of additional value in the work-up of a febrile patient. This study is the first to investigate the additional value of PCT in an Afro-Caribbean febrile population at the emergency department (ED) of a general hospital. Febrile patients were included at the ED. Prospective, blinded PCT measurements were performed in patients with a microbiologically or serologically confirmed diagnosis or a strongly suspected diagnosis on clinical grounds. PCT analysis was performed in 93 patients. PCT levels differentiated well between confirmed bacterial and confirmed viral infection (area under the curve [AUC] of 0.82, sensitivity 85%, specificity 69%, cut-off 0.24 ng/mL), between confirmed bacterial infection and non-infectious fever (AUC of 0.84, sensitivity 90%, specificity 71%, cut-off 0.21 ng/mL) and between all bacterial infections (confirmed and suspected) and non-infectious fever (AUC of 0.80, sensitivity 85%, specificity 71%, cut-off 0.21 ng/mL). C-reactive protein (CRP) levels were shown to be less accurate when comparing the same groups. This is the first study showing that, in a non-Caucasian febrile population at the ED, PCT is a more valuable marker of bacterial infection than CRP. These results may improve diagnostics and eventually decrease antibiotic prescriptions in resource-limited settings

Neuroimaging in Dementia

Dementia is a common illness with an incidence that is rising as the aged population increases. There are a number of neurodegenerative diseases that cause dementia, including Alzheimer’s disease, dementia with Lewy bodies, and frontotemporal dementia, which is subdivided into the behavioral variant, the semantic variant, and nonfluent variant. Numerous other neurodegenerative illnesses have an associated dementia, including corticobasal degeneration, Creutzfeldt–Jakob disease, Huntington’s disease, progressive supranuclear palsy, multiple system atrophy, Parkinson’s disease dementia, and amyotrophic lateral sclerosis. Vascular dementia and AIDS dementia are secondary dementias. Diagnostic criteria have relied on a constellation of symptoms, but the definite diagnosis remains a pathologic one. As treatments become available and target specific molecular abnormalities, differentiating amongst the various primary dementias early on becomes essential. The role of imaging in dementia has traditionally been directed at ruling out treatable and reversible etiologies and not to use imaging to better understand the pathophysiology of the different dementias. Different brain imaging techniques allow the examination of the structure, biochemistry, metabolic state, and functional capacity of the brain. All of the major neurodegenerative disorders have relatively specific imaging findings that can be identified. New imaging techniques carry the hope of revolutionizing the diagnosis of neurodegenerative disease so as to obtain a complete molecular, structural, and metabolic characterization, which could be used to improve diagnosis and to stage each patient and follow disease progression and response to treatment. Structural and functional imaging modalities contribute to the diagnosis and understanding of the different dementias

A search for the decay modes B+/- to h+/- tau l

We present a search for the lepton flavor violating decay modes B+/- to h+/- tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472 million BBbar pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the tau four-momentum. The resulting tau candidate mass is our main discriminant against combinatorial background. We see no evidence for B+/- to h+/- tau l decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10^-5.Comment: 15 pages, 7 figures, submitted to Phys. Rev.

Prior outpatient antibiotic use as predictor for microbial aetiology of community-acquired pneumonia: hospital-based study

Objective: The causative micro-organism in community-acquired pneumonia (CAP) is often difficult to predict. Different studies have examined chronic morbidity and clinical symptoms as predictors for microbial aetiology of pneumonia. The aim of our study was to assess whether prior outpatient antimicrobial treatment is predictive for determining the microbial aetiology of CAP. Methods: This was a hospital-based prospective observational study including all patients admitted with CAP between 1 October 2004 and 1 August 2006. Microbial investigations included sputum, blood culture, sputum PCR, antigen testing and serology. Exposure to antimicrobial drugs prior to hospital admission was ascertained through community pharmacy dispensing records. Multivariate logistic regression analysis was conducted to assess whether prior outpatient antimicrobial treatment is a predictor of microbial aetiology. Patient demographics, co-morbidities and pneumonia severity were considered to be other potential predictors. Results: Overall, 201 patients were included in the study. The microbial aetiology was determined in 64% of the patients. The five most prevalent pathogens were Streptococcus pneumoniae, Heamophilus influenzae, Legionella spp., Mycoplasma pneumoniae and Influenza virus A+B. Forty-seven of the patients (23%) had received initial antimicrobial treatment as outpatients. Multivariate analyses revealed that initial outpatient beta-lactam treatment was associated with a threefold increased chance of finding atypical pathogens and a threefold decreased probability of pneumococcal infection; the corresponding odds ratios were 3.51 (95% CI 1.25-9.99) and 0.30 (95% CI 0.10-0.90), respectively. Patients who received macrolides prior to hospitalisation had an increased probability of viral pneumonia. Conclusion: Prior outpatient antimicrobial therapy has a predictive value in the diagnostic workup aimed at identifying the causative pathogen and planning corresponding antimicrobial treatment in patients hospitalised for pneumonia