Future temperature-related mortality in the UK under climate change scenarios: impact of population ageing and bias-corrected climate projections.

BACKGROUND: Exposure to heat and cold poses a serious threat to human health. In the UK, hotter summers, milder winters and an ageing population will shift how populations experience temperature-related health burdens. Estimating future burdens can provide insights on the drivers of temperature-related health effects and removing biases in temperature projections is an essential step to generating these estimates, however, the impact of various methods of correction is not well examined. METHODS: We conducted a detailed health impact assessment by estimating mortality attributable to temperature at a baseline period (2007-2018) and in future decades (2030s, 2050s and 2070s). Epidemiological exposure-response relationships were derived for all England regions and UK countries, to quantify cold and heat risk, and temperature thresholds where mortality increases. UK climate projections 2018 (UKCP18)were bias-corrected using three techniques: correcting for mean bias (shift or SH), variability (bias-correction or BC) and extreme values (quantile mapping or QM). These were applied in the health impact assessment, alongside consideration of population ageing and growth to estimate future temperature-related mortality. FINDINGS: In the absence of adaptation and assuming a high-end emissions scenario (RCP8.5), annual UK temperature-related mortality is projected to increase, with substantial differences in raw vs. calibrated projections for heat-related mortality, but smaller differences for cold-related mortality. The BC approach gave an estimated 29 deaths per 100,000 in the 2070s, compared with 50 per 100,000 using uncorrected future temperatures. We also found population ageing may exert a bigger impact on future mortality totals than the impact from future increases in temperature alone. Estimating future health burdens associated with heat and cold is an important step towards equipping decision-makers to deliver suitable care to the changing population. Correcting inherent biases in temperature projections can improve the accuracy of projected health burdens to support health protection measures and long-term resilience planning.

Transcriptional regulation of neurodevelopmental and metabolic pathways by NPAS3.

The basic helix-loop-helix PAS (Per, Arnt, Sim) domain transcription factor gene NPAS3 is a replicated genetic risk factor for psychiatric disorders. A knockout (KO) mouse model exhibits behavioral and adult neurogenesis deficits consistent with human illness. To define the location and mechanism of NPAS3 etiopathology, we combined immunofluorescent, transcriptomic and metabonomic approaches. Intense Npas3 immunoreactivity was observed in the hippocampal subgranular zone-the site of adult neurogenesis--but was restricted to maturing, rather than proliferating, neuronal precursor cells. Microarray analysis of a HEK293 cell line over-expressing NPAS3 showed that transcriptional targets varied according to circadian rhythm context and C-terminal deletion. The most highly up-regulated NPAS3 target gene, VGF, encodes secretory peptides with established roles in neurogenesis, depression and schizophrenia. VGF was just one of many NPAS3 target genes also regulated by the SOX family of transcription factors, suggesting an overlap in neurodevelopmental function. The parallel repression of multiple glycolysis genes by NPAS3 reveals a second role in the regulation of glucose metabolism. Comparison of wild-type and Npas3 KO metabolite composition using high-resolution mass spectrometry confirmed these transcriptional findings. KO brain tissue contained significantly altered levels of NAD(+), glycolysis metabolites (such as dihydroxyacetone phosphate and fructose-1,6-bisphosphate), pentose phosphate pathway components and Kreb's cycle intermediates (succinate and α-ketoglutarate). The dual neurodevelopmental and metabolic aspects of NPAS3 activity described here increase our understanding of mental illness etiology, and may provide a mechanism for innate and medication-induced susceptibility to diabetes commonly reported in psychiatric patients.

Using a positive self-talk intervention to enhance coping skills in breast cancer survivors: lessons from a community-based group delivery model.

PURPOSE: Cancer survivorship is a distinct phase of the cancer continuum, and it can have myriad associated stresses and challenges. The purpose of the present study was to evaluate the effectiveness of a positive self-talk (pst) intervention in enhancing the coping skills and improving the psychological well-being of breast cancer survivors. METHODS: Participants (n = 38) were recruited from 5 support groups in a small eastern Canadian province. Support groups were randomly assigned to either a control (n = 18) or an intervention (n = 20) condition. Intervention participants were pre-tested, received a 2-hour pst in-person group workshop and a 10-minute "booster" session by telephone, and completed post-test questionnaires 1 month later. RESULTS: Intervention participants reviewed the workshop favourably. Nearly all participants used the intervention in everyday life, were able to accurately describe how pst works, and found that pst had a considerable impact on their ability to cope with cancer and related sequelae. However, the descriptive findings from the workshop evaluation did not translate into significant differences between the intervention and control groups on the psychometric measures. CONCLUSIONS: The pst intervention, delivered in a community group model, was positively received and effective in teaching participants about pst and how pst can be used to enhance coping skills for breast cancer patients. However, the intervention did not promote significantly greater levels of change in anxiety, depression, mood disturbance, or coping ability for intervention participants. The unique challenges of community-level psychological intervention are explored.

A study of the perceived risks, benefits and barriers to the use of SDD in adult critical care units (the SuDDICU study).

BACKGROUND: Hospital acquired infections are a major cause of morbidity and mortality and markedly increased health care costs. Critically ill patients who require management in an Intensive Care Unit are particularly susceptible to these infections which are associated with a very high mortality. Selective decontamination of the digestive tract (SDD) may reduce these infections and improve mortality but it has not been widely adopted into practice. We aim to 1. Clarify reasons why clinicians have avoided implementing SDD into clinical practice despite the current best-evidence 2. Describe barriers to SDD implementation and 3. Identify what further evidence is required before full scale clinical implementation would be considered appropriate and feasible. METHODS: We have developed an international 'multi-lens' approach to investigate SDD from several perspectives. In case studies we will identify accounts of implementation of SDD in practice, in terms of the behaviours performed by the full range of individual clinicians, accounts of how SDD was first introduced into the Unit and specific content that may be used to populate the content of behaviour change techniques to be used in an implementation intervention and procedures to consider in order to deliver an implementation trial. In a 4 round Delphi study we will identify the range of stakeholders' beliefs, views and perceived barriers relating to the use of SDD. We will generate hypotheses about key beliefs about SDD and will inform the feasibility of any future randomised controlled trial. In large-scale nationwide postal questionnaire surveys of the state of current practice we will identify the factors predicting acceptability of an effectiveness or implementation trial using, and informed by, the theoretical domains structure. In semi-structured interviews with active international clinical trialists we will assess the feasibility of a randomised controlled trial and identify challenges and barriers to undertaking research in the field of SDD research. DISCUSSION: We believe these methods will allow us to determine whether clinical implementation trials or further large effectiveness trials are required before full scale implementation into clinical practice.

A solvent-free matrix application method for matrix-assisted laser desorption/ionization imaging of small molecules.

Matrix application continues to be a critical step in sample preparation for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI). Imaging of small molecules such as drugs and metabolites is particularly problematic because the commonly used washing steps to remove salts are usually omitted as they may also remove the analyte, and analyte spreading is more likely with conventional wet matrix application methods. We have developed a method which uses the application of matrix as a dry, finely divided powder, here referred to as dry matrix application, for the imaging of drug compounds. This appears to offer a complementary method to wet matrix application for the MALDI-MSI of small molecules, with the alternative matrix application techniques producing different ion profiles, and allows the visualization of compounds not observed using wet matrix application methods. We demonstrate its value in imaging clozapine from rat kidney and 4-bromophenyl-1,4-diazabicyclo(3.2.2)nonane-4-carboxylic acid from rat brain. In addition, exposure of the dry matrix coated sample to a saturated moist atmosphere appears to enhance the visualization of a different set of molecules.

Use of a solvent-free dry matrix coating for quantitative matrix-assisted laser desorption ionization imaging of 4-bromophenyl-1,4-diazabicyclo(3.2.2)nonane-4-carboxylate in rat brain and quantitative analysis of the drug from laser microdissected tissue regions.

A dry matrix application for matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) was used to profile the distribution of 4-bromophenyl-1,4-diazabicyclo(3.2.2)nonane-4-carboxylate, monohydrochloride (BDNC, SSR180711) in rat brain tissue sections. Matrix application involved applying layers of finely ground dry alpha-cyano-4-hydroxycinnamic acid (CHCA) to the surface of tissue sections thaw mounted onto MALDI targets. It was not possible to detect the drug when applying matrix in a standard aqueous-organic solvent solution. The drug was detected at higher concentrations in specific regions of the brain, particularly the white matter of the cerebellum. Pseudomultiple reaction monitoring imaging was used to validate that the observed distribution was the target compound. The semiquantitative data obtained from signal intensities in the imaging was confirmed by laser microdissection of specific regions of the brain directed by the imaging, followed by hydrophilic interaction chromatography in combination with a quantitative high-resolution mass spectrometry method. This study illustrates that a dry matrix coating is a valuable and complementary matrix application method for analysis of small polar drugs and metabolites that can be used for semiquantitative analysis.

Long-term modulation of inward currents in O2 chemoreceptors by chronic hypoxia and cyclic AMP in vitro.

In mammals, ventilatory acclimatization to hypoxia is associated with an enhanced chemosensitivity of the O2-sensing carotid body, resulting in an increased respiratory drive. To test whether this sensitization involves long-term modulation of ion channel function in endogenous O2 chemoreceptors, i.e., type 1 cells, we exposed cultures of dissociated rat carotid body to chronic hypoxia (6% O2) for 1-2 weeks, before monitoring the electrophysiological properties of type 1 cells using whole-cell, perforated patch recording. Chronic hypoxia augmented voltage-dependent inward Na+ and Ca2+ currents in type 1 cells, without significant changes in voltage dependence of activation or steady-state inactivation. However, after normalizing for the concomitant increase in cell size, indicated by the whole-cell capacitance, only the Na+ current density was significantly enhanced. The Na+ current was sensitive to tetrodotoxin (TTX; 0.5-1 microM) or choline substitution, whereas most of the Ca2+ current was sensitive to the L-type calcium channel blocker, nifedipine (10 microM). Several of these effects of hypoxia were mimicked qualitatively by growing normoxic cultures in the presence of agents that elevate intracellular cyclic AMP, including dibutyryl cAMP (db-cAMP; 200 microM-1 mM) and forskolin (10 microM); treatment with similar concentrations of dibutyryl cyclic GMP was ineffective. Na+ channel induction by db-cAMP was abolished by the protein synthesis inhibitor, cycloheximide (90-180 microM). In current-clamp mode, these altered chemoreceptors had typical resting potentials of approximately -55 mV, and following depolarization often fired multiple spikes that appeared to consist of both short-duration Na+ and long-duration Ca2+ components. We propose that chronic hypoxia, acting in part through cAMP-dependent pathways, increases electrical excitability and calcium mobilization in type 1 cells, and these adaptations may help enhance chemosensitivity during hypoxic acclimatization.

Axonal domains within shared touch domes in the rat: a comparison of their fate during conditions favoring collateral sprouting and following axonal regeneration.

Low-threshold mechanosensory nerves in the adult rat differ both from their counterparts in lower vertebrates and from high-threshold nociceptive nerves in mammals in that they appear not to undergo collateral sprouting into adjacent denervated skin, although they will clearly regenerate into it after they are damaged. We have now studied the growth capabilities of the low-threshold nerves supplying touch domes, the visible mechanosensory structures scattered throughout the hairy skin. Touch domes in the rat are often multiply innervated. A serendipitous observation on such domes allowed us to investigate the possibility that a functional collateral sprouting of their nerves can indeed occur, but only to a spatially very restricted extent, e.g., within the confines of a partially denervated dome. We used a "prodder" with a tip diameter of 16 micron to examine the mechanosensory profile across single domes that were preselected as being supplied by only two axons, one running in each of two adjacent dorsal cutaneous nerves (DCNs). Simultaneous recordings were made of the afferent discharges evoked in these nerves when the prodder was applied at about 17 or more locations on a selected dome; the spatial resolution was better than 55 micron. We found that within such a shared dome, one axon can supply a discrete territory (its "domain"), which may or may not overlap with the corresponding domain of the other axon. In a preliminary electron microscopic study, we found no evidence for a sharing of single Merkel cells, which are the specialized sensory cells in touch domes, even in the regions of a shared dome where two domains overlapped; each innervated Merkel cell appeared to be contacted by a single nerve ending, implying that in a shared dome each axon probably supplies an exclusive subpopulation of the Merkel cells. We tested for functional collateral sprouting by eliminating one nerve to a shared dome, and at a selected time thereafter mapping the domain of the remaining axon to see whether it had enlarged. The result was the same whether the two domains initially had a region of overlap or not; no expansion of the surviving domain occurred over postoperative periods up to 4 months (an expansion of the domain by 55 micron would have been detected). Thus functional collateral sprouting had failed to occur.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence that endogenous beta nerve growth factor is responsible for the collateral sprouting, but not the regeneration, of nociceptive axons in adult rats.

A key role has not yet been identified for beta nerve growth factor (NGF) in the growth responses that continue to be expressed in the sensory neurons of adult animals. We have now examined the effects of daily administration to adult rats (and in a few experiments, mice) of antiserum to NGF on (i) the collateral sprouting of undamaged nociceptive nerves that occurs into denervated adjacent skin and (ii) the regeneration of cutaneous sensory axons that occurs after they are damaged. The results were unexpected. All collateral sprouting was prevented and that already in progress was halted; sprouting resumed when treatment was discontinued. In contrast, the reestablishment, and even enlargement, of cutaneous nerve fields by regenerating axons was unaffected by anti-NGF treatment, even after dorsal rhizotomy was done to eliminate any central trophic support. In denervated skin, regenerating and collaterally sprouting axons utilized the same cellular pathways to establish functionally identical fields, thus displaying apparently identical growth behaviors, yet anti-NGF treatment clearly distinguished between them. We suggest that endogenous NGF is responsible for the collateral sprouting of nociceptive axons, probably reflecting an ongoing function of NGF in the regulation of their fields. This demonstration in the adult sensory system of a defined role for NGF in nerve growth could apply to nerve growth factors generally in the adult nervous system. The regeneration, however, of nociceptive axons (and nonnociceptive one) is not dependent on NGF.

Reinnervation of the rat touch dome restores the Merkel cell population reduced after denervation.

By using the fluorescent dye quinacrine as a marker for the Merkel cells in the rat touch dome, we previously showed that a sustained denervation of the dome causes a rapid and persistent loss of about 60% of its Merkel cells [Nurse, Macintyre and Diamond (1984) Neuroscience 11, 521-533]. We now show that if the sensory nerves to the skin are crushed (or cut) in 2-week old pups and allowed to regenerate, the Merkel cell population within touch domes shows a biphasic response; there is an initial loss of Merkel cells associated with the early phase of denervation, followed by an increase, associated with the phase of reinnervation. Physiological tests revealed that many (though not all) domes within initially deafferented skin had become functionally reinnervated and had their Merkel cell numbers either wholly or partially restored some 40-100 days post operatively. In one case an adult reinnervated dome, that appeared normal physiologically and by its complement of quinacrine fluorescent (Merkel) cells, also had normal histological features in toluidine blue sections and normally innervated Merkel cells in the electron microscope. These results, based on the use of quinacrine to visualize the Merkel cell population in the touch dome, suggest that sensory nerves may induce the differentiation of new Merkel cells in domes where these cells have become reduced after denervation.

A quantitative study of the time course of the reduction in Merkel cell number within denervated rat touch domes.

By using the fluorescent dye quinacrine as a marker for the Merkel cells in rat touch domes we have shown that denervation results in a progressive reduction in the number of these cells to a level that remains relatively constant at about 40% of that present at the time of denervation. The time-course of quinacrine fluorescent cell changes after denervation could be described by assuming that (i) there are two populations of quinacrine fluorescent cells, one labile and the other stable, and (ii) the labile population is the one most sensitive to denervation and disappears exponentially with a half-time of ca 10 days. It appeared that this time-course of decay of the labile quinacrine fluorescent cells was the same whether the denervation was performed during the period of postnatal development studied (at 7 and 14 days), when normally Merkel cells are rapidly added to the dome, or later (at 35 and 60 days) when the adult population is virtually established. Correlative electron microscopic studies confirmed that quinacrine fluorescent cell counts reflect fairly accurately the Merkel cell population in denervated domes. These quantitative findings based on the use of quinacrine to visualize the entire Merkel cell population of touch domes show that the normal development and maintenance of these cells are trophically dependent on sensory nerves, although a subpopulation may persist even in long-term denervated domes. In addition, the similarity of the first order rate constant for the decay of quinacrine fluorescent cells after denervation and for the normal generation of quinacrine fluorescent cells suggests that the labile Merkel cell population is one that turns over continuously in the normally innervated touch dome.

Competitive reinnervation of salamander skin by regenerating and intact mechanosensory nerves.

We have investigated in the salamander the possibility that regenerating mechanosensory nerves might prefer the epidermal Merkel cells (their specific targets) that are located within their segmental domain to those within a "foreign" domain. Since regerating nerves cross domain boundaries with no evidence of the marked delay exhibited by intact sprouting nerves, we examined situations in which the regenerating axons of one segmental nerve were effectively in equal competition for denervated skin with those of another segmental nerve. Additionally, we investigated whether there were differences between regenerating axons and intact sprouting axons of the same segmental nerve, in their ability to innervate available skin both inside and outside the parent domain. No preference was detected of any type of nerve, regenerating or intact, for particular skin regions, or for Merkel cells as indicated by the numbers of mechanosensory thresholds of the touch spots that developed in reinnervated skin. Neither was there any indicating of displacement of "foreign" nerves from a particular region by appropriate axons. When regenerating and intact (sprouting) axons invaded denervated skin more or less simultaneously, the former appeared to have a slight advantage since a significantly greater proportion of skin was innervated by regenerated fibres. With this one exception, all the results were explained most simply by assuming that the axon that first arrives at a denervated Merkel cell establishes a permanent association with that cell and at the same time causes it to lose its "target character" for other axons.