Heterogeneity in Surface Sensing Suggests a Division of Labor in Pseudomonas aeruginosa Populations

The second messenger signaling molecule cyclic diguanylate monophosphate (c-di-GMP) drives the transition between planktonic and biofilm growth in many bacterial species. Pseudomonas aeruginosa has two surface sensing systems that produce c-di-GMP in response to surface adherence. Current thinking in the field is that once cells attach to a surface, they uniformly respond by producing c-di-GMP. Here, we describe how the Wsp system generates heterogeneity in surface sensing, resulting in two physiologically distinct subpopulations of cells. One subpopulation has elevated c-di-GMP and produces biofilm matrix, serving as the founders of initial microcolonies. The other subpopulation has low c-di-GMP and engages in surface motility, allowing for exploration of the surface. We also show that this heterogeneity strongly correlates to surface behavior for descendent cells. Together, our results suggest that after surface attachment, P. aeruginosa engages in a division of labor that persists across generations, accelerating early biofilm formation and surface exploration

‘Socialised care futility’ in the care of older people in hospital who call out repetitively: an ethnographic study

BackgroundPeople living with dementia may call out repetitively, sometimes called disruptive vocalisation, or verbal agitation. In literature and policy, patients who call out repetitively are assumed to be expressing an unmet need, which should be met. Yet there has been little systematic study of this patient group in an acute hospital setting.ObjectivesTo better understand patients who call out repetitively and to identify what care looks like in an acute hospital setting.DesignEthnography.SettingsTen acute geriatric medical wards in two hospitals.Participants30 cognitively impaired patients who were calling out repetitively, and 15 members of hospital staff.MethodsSemi-structured interviews with hospital staff, 150 hours of ward observations and informal conversations with staff, scrutiny of medical and nursing documentation, and measures of patient health status.ResultsPatients who called out were moderately or severely cognitively impaired, often had delirium, were very physically disabled, and many were approaching the end of life. Most hospital staff were found to hold contradictory views: that calling out represents distress or unmet need, but that nothing can be done to alleviate the calling out. During informal conversations, most staff also tended to say that they intuitively recognised when intervening was likely to alleviate calling out. During observations, many staff appeared to and spoke of the ability to ‘block’ calling out. As a result we argue that social, emotional and physical needs may get overlooked. We argue that some calling out of a need, represents a need that is unmeetable. We also found that while staff would talk about strategies for identifying need, observations and hospital documentation did not support evidence of systematic attempts to identify potential need.ConclusionCalling out repetitively within a hospital setting is difficult for staff to understand and to respond to. This is because many of these patients are severely cognitively impaired, while also bed-bound and dependent on their professional carers. We argue that a form of socialised care futility gets communicated between staff and is used to rationalise becoming unresponsive to calling-out. We explain this phenomenon as resulting from two protective mechanisms: defence of staff's professional identity as competent practitioners; and defence of staff as having personal morality. Socialised care futility risks good quality care, therefore systematic strategies to assess and manage possible need should be developed, even if calling out remains irresolvable in some cases

Community health workers can improve child growth of antenatally-depressed, South African mothers : a cluster randomized controlled trial

CITATION: Tomlinson, M., et al. 2015. Community health workers can improve child growth of antenatally-depressed, South African mothers : a cluster randomized controlled trial. BMC Psychiatry, 15:225, doi:10.1186/s12888-015-0606-7.The original publication is available at https://bmcpsychiatry.biomedcentral.comBackground: Maternal antenatal depression has long-term consequences for children’s health. We examined if home visits by community health workers (CHW) can improve growth outcomes for children of mothers who are antenatally depressed. Methods: A cluster randomized controlled trial of all pregnant, neighbourhood women in Cape Town, South Africa. Almost all pregnant women (98 %, N = 1238) were recruited and assessed during pregnancy, two weeks post-birth (92 %) and 6 months post-birth (88 %). Pregnant women were randomized to either: 1) Standard Care (SC), which provided routine antenatal care; or 2) an intervention, The Philani Intervention Program (PIP), which included SC and home visits by CHW trained as generalists (M = 11 visits). Child standardized weight, length, and weight by length over 6 months based on maternal antenatal depression and intervention condition. Results: Depressed mood was similar across the PIP and SC conditions both antenatally (16.5 % rate) and at 6 months (16.7 %). The infants of depressed pregnant women in the PIP group were similar in height (height-forage Z scores) to the children of non-depressed mothers in both the PIP and the SC conditions, but significantly taller at 6 months of age than the infants of pregnant depressed mothers in the SC condition. The intervention did not moderate children’s growth. Depressed SC mothers tended to have infants less than two standard deviations in height on the World Health Organization’s norms at two weeks post-birth compared to infants of depressed PIP mothers and non-depressed mothers in both conditions. Conclusions: A generalist, CHW-delivered home visiting program improved infant growth, even when mothers’ depression was not reduced. Focusing on maternal caretaking of infants, even when mothers are depressed, is critical in future interventions.https://bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-015-0606-7Publisher's versio

Experimental uptake and depuration of paralytic shellfish toxins in Southern Rock Lobster, Jasus edwardsii

In October 2012, paralytic shellfish toxins (PST) were detected in the hepatopancreas of Southern Rock Lobsters (Jasus edwardsii) collected from the east coast of Tasmania, Australia. This resulted in the first commercial closure in Australia for this species. Questions were raised on how the toxins were transferred to the lobsters, how long the toxins would persist, whether PST-contaminated hepatopancreas posed a risk to human health, and what management strategies could be applied. The aim of this study was to investigate whether PST-contaminated mussels are a potential vector enabling toxin accumulation in J. edwardsii and to collect information on toxin uptake, distribution and depuration rates and toxin profiles under controlled experimental settings. Lobsters were fed mussels naturally contaminated with PST for a period of 28 days in an experimental setting; following this, lobsters were allocated to either fed or starved treatment groups. PST were not detected in the tail tissue of lobsters at any stage of the experiment. Lobster hepatopancreas contained mean levels of 2.4\ua0mg STX.2HCl eq/kg after 28 days of uptake, although substantial variability in total toxicity was observed. The PST profile of the hepatopancreas was similar to that of the contaminated mussels used as feed. Significant differences were noted in the PST depuration rates between fed and starved treatment groups. The daily depuration rate for total PST was estimated to be 0.019 and 0.013\ua0mg STX.2HCl eq/kg for the fed and starved treatment groups respectively using a constant-rate decay model. After 42 days of depuration, total PST (STX equivalents) levels in the hepatopancreas of all lobsters were below 0.8\ua0mg STX.2HCl eq/kg, which represents the regulatory level applied to bivalves. This result indicates that long-term holding to depurate PST may potentially be used as a risk management tool

The association of neurodevelopmental abnormalities, congenital heart and renal defects in a Tuberous Sclerosis Complex patient cohort

Background: Tuberous sclerosis complex (TSC) is a rare multi-system genetic disorder characterised by the presence of benign tumours throughout multiple organs including the brain, kidneys, heart, liver, eyes, lungs and skin, in addition to neurological and neuropsychiatric complications. Intracardiac tumour (rhabdomyoma), neurodevelopmental disorders (NDDs) and kidney disorders (KD) are common manifestations of TSC and have been linked with TSC1 and TSC2 loss-of-function mutations independently, but the dynamic relationship between these organ manifestations remains unexplored. Therefore, this study aims to characterise the nature of the relationship specifically between these three organs' manifestations in TSC1 and TSC2 mutation patients. Methods: Clinical data gathered from TSC patients across South Wales registered with Cardiff and Vale University Health Board (CAV UHB) between 1990 and 2020 were analysed retrospectively to evaluate abnormalities in the heart, brain and kidney development. TSC-related abnormalities such as tumour prevalence, location and size were analysed for each organ in addition to neuropsychiatric involvement and were compared between TSC1 and TSC2 mutant genotypes. Lastly, statistical co-occurrence between organ manifestations co-morbidity was quantified, and trajectories of disease progression throughout organs were modelled. Results: This study found a significantly greater mutational frequency at the TSC2 locus in the cohort in comparison to TSC1. An equal proportion of male and female patients were observed in this group and by meta-analysis of previous studies. No significant difference in characterisation of heart involvement was observed between TSC1 and TSC2 patients. Brain involvement was seen with increased severity in TSC2 patients, characterised by a greater prevalence of cortical tubers and communication disorders. Renal pathology was further enhanced in TSC2 patients, marked by increased bilateral angiomyolipoma prevalence. Furthermore, co-occurrence of NDDs and KDs was the most positively correlated out of investigated manifestations, regardless of genotype. Analysis of disease trajectories revealed a more diverse clinical outcome for TSC2 patients: however, a chronological association of rhabdomyoma, NDD and KD was most frequently observed for TSC1 patients. Conclusions: This study marks the first empirical investigation of the co-morbidity between congenital heart defects (CHD), NDDs, and KDs in TSC1 and TSC2 patients. This remains a unique first step towards the characterisation of the dynamic role between genetics, heart function, brain function and kidney function during the early development in the context of TSC

Is looped nasogastric tube feeding more effective than conventional nasogastric tube feeding for dysphagia in acute stroke?

Background: Dysphagia occurs in up to 50% of patients admitted to hospital with acute strokes with up to 27% remaining by seven days. Up to 8% continue to have swallowing problems six months after their stroke with 1.7% still requiring enteral feeding. Nasogastric tubes (NGT) are the most commonly used method for providing enteral nutrition in early stroke, however they are easily and frequently removed leading to inadequate nutrition, early PEG (Percutaneous Endoscopic Gastrostomy) insertion or abandoning of feeding attempts. Looped nasogastric tube feeding may improve the delivery of nutrition to such patients. Methods: Three centre, two arm randomised controlled trial, with 50 participants in each arm comparing loop (the intervention) versus conventional nasogastric tube feeding. The primary outcome measure is proportion of intended feed delivered in the first 2 weeks. The study is designed to show a mean increase of feed delivery of 16% in the intervention group as compared with the control group, with 90% power at a 5% significance level. Secondary outcomes are treatment failures, mean volume of feed received, adverse events, cost-effectiveness, number of chest x-rays, number of nasogastric tubes and tolerability

Mechanistic consequences of temperature on DNA polymerization catalyzed by a Y-family DNA polymerase

Our previous publication shows that Sulfolobus solfataricus Dpo4 utilizes an ‘induced-fit’ mechanism to select correct incoming nucleotides at 37°C. Here, we provide a comprehensive report elucidating the kinetic mechanism of a DNA polymerase at a reaction temperature higher than 37°C in an attempt to determine the effect of temperature on enzyme fidelity and mechanism. The fidelity of Dpo4 did not change considerably with a 30°C increase in reaction temperature, suggesting that the fidelity of Dpo4 at 80°C is similar to that determined here at 56°C. Amazingly, the incorporation rate for correct nucleotides increased by 18 900-fold from 2°C to 56°C, similar in magnitude to that observed for incorrect nucleotides, thus not perturbing fidelity. Three independent lines of kinetic evidence indicate that a protein conformational change limits correct nucleotide incorporations at 56°C. Furthermore, the activation energy for the incorporation of a correct nucleotide was determined to be 32.9 kcal/mol, a value considerably larger than those values estimated for a rate-limiting chemistry step, providing a fourth line of evidence to further substantiate this conclusion. These results herein provide evidence that Dpo4 utilizes the ‘induced-fit’ mechanism to select a correct nucleotide at all temperatures

Dihimo-γ-linolenic acid inhibits several key cellular processes associated with atherosclerosis

Atherosclerosis and its complications are responsible for one in three global deaths. Nutraceuticals show promise in the prevention and treatment of atherosclerosis but require an indepth understanding of the mechanisms underlying their actions. A previous study showed that the omega-6 fatty acid, dihomo-γ-linolenic acid (DGLA), attenuated atherosclerosis in the apolipoprotein E deficient mouse model system. However, the mechanisms underlying such protective effects of DGLA are poorly understood and were therefore investigated. We show that DGLA attenuates chemokine-driven monocytic migration together with foam cell formation and the expression of key pro-atherogenic genes induced by three pro-inflammatory cytokines in human macrophages. The effect of DGLA on interferon-γ signaling was mediated via inhibition of signal transducer and activator of transcription-1 phosphorylation on serine 727. In relation to anti-foam cell action, DGLA inhibits modified LDL uptake by both macropinocytosis and receptor-mediated endocytosis, the latter by reduction in expression of two key scavenger receptors (SR-A and CD36), and stimulates cholesterol efflux from foam cells. DGLA also improves macrophage mitochondrial bioenergetic profile by decreasing proton leak. Gamma-linolenic acid and prostaglandin E1, upstream precursor and key metabolite respectively of DGLA, also acted in an anti-atherogenic manner. The actions of DGLA extended to other key atherosclerosis-associated cell types with attenuation of endothelial cell proliferation and migration of smooth muscle cells in response to platelet-derived growth factor. This study provides novel insights into the molecular mechanisms underlying the anti-atherogenic actions of DGLA and supports further assessments on its protective effects on plaque regression in vivo and in human trials

Antigen-specific B-cell receptor sensitizes B cells to infection by influenza virus

Influenza A virus-specific B lymphocytes and the antibodies they produce protect against infection. However, the outcome of interactions between an influenza haemagglutinin-specific B cell via its receptor (BCR) and virus is unclear. Through somatic cell nuclear transfer we generated mice that harbour B cells with a BCR specific for the haemagglutinin of influenza A/WSN/33 virus (FluBI mice). Their B cells secrete an immunoglobulin gamma 2b that neutralizes infectious virus. Whereas B cells from FluBI and control mice bind equivalent amounts of virus through interaction of haemagglutinin with surface-disposed sialic acids, the A/WSN/33 virus infects only the haemagglutinin-specific B cells. Mere binding of virus is not sufficient for infection of B cells: this requires interactions of the BCR with haemagglutinin, causing both disruption of antibody secretion and FluBI B-cell death within 18 h. In mice infected with A/WSN/33, lung-resident FluBI B cells are infected by the virus, thus delaying the onset of protective antibody release into the lungs, whereas FluBI cells in the draining lymph node are not infected and proliferate. We propose that influenza targets and kills influenza-specific B cells in the lung, thus allowing the virus to gain purchase before the initiation of an effective adaptive response.National Institutes of Health (U.S.