Exploring mechanisms and contexts in a Peer Education Project to improve mental health literacy in schools in England: a qualitative realist evaluation

Poor adolescent mental health calls for universal prevention. The Mental Health Foundation's 'Peer Education Project' equips older students ('peer educators') to teach younger students ('peer learners') about mental health. The peer-led lessons cover defining good and bad mental health, risk and protective factors, self-care, help-seeking and looking after one another. While previous pre-post evaluations have suggested effectiveness, the mechanisms through which the intervention improves mental health literacy remain unclear. We purposively recruited seven secondary schools across England from 2020 to 2022 and collected data through five observations, 12 staff interviews and 15 student focus groups (totalling 134 students; 46 peer educators aged 14-18 years and 88 peer learners aged 11-13 years). Our realist analysis adopted retroductive logic, intertwining deductive and inductive approaches to test the initial programme theory against insights arising from the data. We developed Context-Mechanisms-Outcome configurations related to four themes: (i) modelling behaviours and forming supportive relationships, (ii) relevant and appropriate content, (iii) peer educators feeling empowered and (iV) a school culture that prioritises mental health support. Our refined programme theory highlights key mechanisms, contexts conducive to achieving the outcomes and ways to improve training, recruitment and delivery to maximise effectiveness for similar peer-led initiatives.

Evaluating the trophic transfer of PCBs from fish to humans: Insights from a synergism of environmental monitoring and physiologically-based pharmacokinetic modeling

Accumulation of polychlorinated biphenyls (PCBs) within fish tissues has prompted many states to issue consumption advisories. In Pennsylvania such advisories suggest one meal per month for most game species harvested from Lake Erie; however, these advisories do not account for the emergent properties of regional PCB mixtures, and the downstream accumulation of PCB congeners into human tissues is poorly documented. This study aimed to demonstrate the utility of pairing environmental monitoring with pharmacokinetic modeling for the purpose of estimating dietary PCB exposure in humans. We qualified and quantified the PCB congeners present in the filets of five Lake Erie fish species and used these data to estimate exposure under consumption scenarios that matched or exceeded the advisories. Physiologically-based pharmacokinetic (PBPK) modeling was then employed to predict PCB accumulation within seven tissue compartments of a hypothetical man and woman over 10 years. Twenty-one congeners were detected between the five fish species at concentrations ranging from 56.0 to 411.7 ng/g. Predicted accumulation in human tissues varied based on tissue type, the species consumed, biological sex, and fish-consumption rate. Notably, steady-state concentrations were higher in fatty tissue compartments ("Fat" and "Liver") and across all tissues in women compared to men. This study serves as a preliminary blueprint for generating predictions of site-specific and tissue-specific exposure through the integration of environmental monitoring and pharmacokinetic modeling. Although the details may vary across applications, this simple approach could complement traditional exposure assessments for vulnerable communities in the Great Lakes region that continue to suffer from legacy contamination.

Toward a human brain extracellular vesicle atlas: Characteristics of extracellular vesicles from different brain regions, including small RNA and protein profiles

Extracellular vesicles (EVs) are released from different cell types in the central nervous system (CNS) and play roles in regulating physiological and pathological functions. Although brain-derived EVs (bdEVs) have been successfully collected from brain tissue, there is not yet a "bdEV Atlas" of EVs from different brain regions. To address this gap, we separated EVs from eight anatomical brain regions of a single individual and subsequently characterized them by count, size, morphology, and protein and RNA content. The greatest particle yield was from cerebellum, while the fewest particles were recovered from the orbitofrontal, postcentral gyrus, and thalamus regions. EV surface phenotyping indicated that CD81 and CD9 were more abundant than CD63 in all regions. Cell-enriched surface markers varied between brain regions. For example, putative neuronal markers NCAM, CD271, and NRCAM were more abundant in medulla, cerebellum, and occipital regions, respectively. These findings, while restricted to tissues from a single individual, suggest that additional studies are warranted to provide more insight into the links between EV heterogeneity and function in the CNS.

Towards a human brain EV atlas: Characteristics of EVs from different brain regions, including small RNA and protein profiles

Extracellular vesicles (EVs) are released from different cell types in the central nervous system (CNS) and play roles in regulating physiological and pathological functions. Although brain-derived EVs (bdEVs) have been successfully collected from brain tissue, there is not yet a "bdEV atlas" of EVs from different brain regions. To address this gap, we separated EVs from eight anatomical brain regions of a single individual and subsequently characterized them by count, size, morphology, and protein and RNA content. The greatest particle yield was from cerebellum, while the fewest particles were recovered from the orbitofrontal, postcentral gyrus, and thalamus regions. EV surface phenotyping indicated that CD81 and CD9 were more abundant than CD63 for all regions. Cell-enriched surface markers varied between brain regions. For example, putative neuronal markers NCAM, CD271, and NRCAM were more abundant in medulla, cerebellum, and occipital regions, respectively. These findings, while restricted to tissues from a single individual, suggest that additional studies are merited to lend more insight into the links between EV heterogeneity and function in the CNS.

Intermittent systemic exposure to lipopolysaccharide-induced inflammation disrupts hippocampal long-term potentiation and impairs cognition in aging male mice

Age-related cognitive decline, a common component of the brain aging process, is associated with significant impairment in daily functioning and quality of life among geriatric adults. While the complexity of mechanisms underlying cognitive aging are still being elucidated, microbial exposure and the multifactorial inflammatory cascades associated with systemic infections are emerging as potential drivers of neurological senescence. The negative cognitive and neurobiological consequences of a single pathogen-associated inflammatory experience, such as that modeled through treatment with lipopolysaccharide (LPS), are well documented. Yet, the brain aging impacts of repeated, intermittent inflammatory challenges are less well studied. To extend the emerging literature assessing the impact of infection burden on cognitive function among normally aging mice, here, we repeatedly exposed adult mice to intermittent LPS challenges during the aging period. Male 10-month-old C57BL6 mice were systemically administered escalating doses of LPS once every two weeks for 2.5 months. We evaluated cognitive consequences using the non-spatial step-through inhibitory avoidance task, and both spatial working and reference memory versions of the Morris water maze. We also probed several potential mechanisms, including cortical and hippocampal cytokine/chemokine gene expression, as well as hippocampal neuronal function via extracellular field potential recordings. Though there was limited evidence for an ongoing inflammatory state in cortex and hippocampus, we observed impaired learning and memory and a disruption of hippocampal long-term potentiation. These data suggest that a history of intermittent exposure to LPS-induced inflammation is associated with subtle but significantly impaired cognition among normally aging mice. The broader impact of these findings may have important implications for standard of care involving infections in aging individuals or populations at-risk for dementia.

miR-146a Dysregulates Energy Metabolism During Neuroinflammation

Alzheimer's disease (AD) and other neurodegenerative diseases are characterized by chronic neuroinflammation and a reduction in brain energy metabolism. An important role has emerged for small, non-coding RNA molecules known as microRNAs (miRNAs) in the pathophysiology of many neurodegenerative disorders. As epigenetic regulators, miRNAs possess the capacity to regulate and fine tune protein production by inhibiting translation. Several miRNAs, which include miR-146a, are elevated in the brain, CSF, and plasma of AD patients. miR-146a participates in pathways that regulate immune activation and has several mRNA targets which encode for proteins involved in cellular energy metabolism. An additional role for extracellular vesicles (EVs) has also emerged in the progression AD, as EVs can transfer functionally active proteins and RNAs from diseased to healthy cells. In the current study, we exposed various cell types present within the CNS to immunomodulatory molecules and observed significant upregulation of miR-146a expression, both within cells and within their secreted EVs. Further, we assessed the effects of miR-146a overexpression on bioenergetic function in primary rat glial cells and found significant reductions in oxidative phosphorylation and glycolysis. Lastly, we correlated miR-146a expression levels within various regions of the AD brain to disease staging and found significant, positive correlations. These novel results demonstrate that the modulation of miR-146a in response to neuroinflammatory stimuli may mediate the loss of mitochondrial integrity and function in cells, thereby contributing to the progression of beta-amyloid and tau pathology in the AD brain. Multiple inflammatory stimuli can upregulate miRNA-146a expression within neurons, mixed glial cells, and brain endothelial cells, which is either retained within these cells or released from them as extracellular vesicle cargo. The upregulation of miR-146a disrupts cellular bioenergetics in mixed glial cells. This mechanism may play a critical role in the neuroinflammatory response observed during Alzheimer's disease.

Cigarette smoke-induced extracellular vesicles from dendritic cells alter T-cell activation and HIV replication

Despite decreased rates of tobacco smoking in many areas, cigarette smoking remains a major contributor to many health problems. Cigarette smoking can reduce immune system functioning while concurrently increasing inflammation. Dendritic cells in the lung exposed to cigarette smoke become stimulated and go on to activate T-cells. Extracellular vesicles (EVs) are nano-sized particles released by cells. They participate in intercellular communication by transferring functional proteins and nucleic acids to recipient cells and have been implicated in immune responses. For example, they can display MHC-peptide complexes to activate T-cells. In the current study, we sought to understand the role of cigarette smoke extract (CSE) on dendritic cell-derived EVs and their capacity to activate and differentiate T-cells. Primary human dendritic cells (iDCs) were exposed to CSE and EVs were separated and characterized. We exposed autologous primary CD4 + T-cells to iDC-EVs and observed T helper cell populations skewing towards Th1 and Th17 phenotypes. As HIV + individuals are disproportionately likely to be current smokers, we also examined the effects of iDC-EVs on acutely infected T-cells as well as on a cell model of HIV latency (ACH-2). We found that in most cases, iDC-CSE EVs tended to reduce p24 release from the acutely infected primary T-cells, albeit with great variability. We did not observe large effects of iDC-EVs or direct CSE exposure on p24 release from the ACH-2 cell line. Together, these data suggest that iDC-CSE EVs have the capacity to modulate the immune responses, in part by pushing T-cells towards Th1 and Th17 phenotypes.

A novel fuel cell design foroperandoenergy-dispersive x-ray absorption measurements

A polymer electrolyte fuel cell has been designed to allowoperandox-ray absorption spectroscopy (XAS) measurements of catalysts. The cell has been developed to operate under standard fuel cell conditions, with elevated temperatures and humidification of the gas-phase reactants, both of which greatly impact the catalyst utilisation. X-ray windows in the endplates of the cell facilitate collection of XAS spectra during fuel cell operation while maintaining good compression in the area of measurement. Results of polarisation curves and cyclic voltammograms showed that theoperandocell performs well as a fuel cell, while also providing XAS data of suitable quality for robust XANES analysis. The cell has produced comparable XAS results when performing a cyclic voltammogram to an establishedin situcell when measuring the Pt LIII edge. Similar trends of Pt oxidation, and reduction of the formed Pt oxide, have been presented with a time resolution of 5 s for each spectrum, paving the way for time-resolved spectral measurements of fuel cell catalysts in a fully-operating fuel cell.

Intermittent Lipopolysaccharide Exposure Significantly Increases Cortical Infarct Size and Impairs Autophagy

Globally, stroke is a leading cause of death and disability. Traditional risk factors like hypertension, diabetes, and obesity do not fully account for all stroke cases. Recent infection is regarded as changes in systemic immune signaling, which can increase thrombosis formation and other stroke risk factors. We have previously shown that administration of lipopolysaccharide (LPS) 30-minutes prior to stroke increases in infarct volume. In the current study, we found that animals intermittently exposed to LPS have larger cortical infarcts when compared to saline controls. To elucidate the mechanism behind this phenomenon, several avenues were investigated. We observed significant upregulation of tumor necrosis factor-alpha (TNF-α) mRNA, especially in the ipsilateral hemisphere of both saline and LPS exposed groups compared to sham surgery animals. We also observed significant reductions in expression of genes involved in autophagy in the ipsilateral hemisphere of LPS stroke animals. In addition, we assessed DNA methylation of autophagy genes and observed a significant increase in the ipsilateral hemisphere of LPS stroke animals. Intermittent exposure to LPS increases cortical infarct volume, downregulates autophagy genes, and induces hypermethylation of the corresponding CpG islands. These data suggest that intermittent immune activation may deregulate epigenetic mechanisms and promote neuropathological outcomes after stroke.

Feasibility of salivary cortisol collection in patients and companions attending dementia diagnostic meetings in memory clinics

Objectives

Receiving a diagnosis of dementia is life-changing for the individual and their companion. The aim of the study was to explore the feasibility of collecting salivary cortisol from patients who are informed if they have dementia and their companions. Patients and companions collected nine saliva samples in three batches: 1–2 weeks before, immediately before, and immediately after the diagnostic meeting. Each batch consisted of three samples taken in the evening, after awaking and 30 mins post-waking.

Results

22.7% (N = 10) of 44 invited patients and nine companions agreed, with 18.2% patients (N = 8) and 15.9% companions (N = 7) providing samples. Participants found that saliva collection was demanding and disrupted routines. On a purely descriptive level, some indications of an increased cortisol stress response in patients diagnosed with dementia were found in this very small sample. Researchers should expect low recruitment rates in this elderly population. Simpler collection procedures, e.g. pre-labelled packages with date/time, possible omission of morning samples and objective rather than self-report assessment of waking and saliva collection times—using actigraphy wrist-watches bleeps to prompt people at the timepoints and electronic track caps—might improve adherence and improve the accuracy of timepoints when swabs were actually collected.

Barriers and predictors of medication use for childhood ADHD: findings from a UK population-representative cohort

PURPOSE

Little is known about sociodemographic and clinical factors that predict and act as barriers to ADHD medication independently of symptom severity. We examined the proportion of children using medication for ADHD, age of initiation of medication, and predictors of medication use in a population-representative cohort.

METHODS

Data from the Millennium Cohort Study on child ADHD, medication use for ADHD at age 14 (in 2014-2015) and child, parent and sociodemographic variables were collated. Logistic regression models were used to identify factors that predict medication use for ADHD (the main outcome measure), adjusting for symptom severity at age seven.

RESULTS

The weighted prevalence of ADHD was 3.97% (N = 11,708). 45.57% of children with ADHD (N = 305) were taking medication. The median age at initiation was 9 years (range 3-14). Male gender (AOR 3.66, 95% CI 1.75, 7.66) and conduct problems at age seven (AOR 1.24 95% CI 1.04, 1.47) and 14 predicted medication use at age 14 after adjusting for symptom severity.

CONCLUSIONS

Our study is the first to assess predictors of medication whist adjusting for ADHD symptom severity. Girls with ADHD were less likely to be prescribed medication, even when they displayed similar ADHD symptom levels to boys. Conduct problems also predicted medication independently of ADHD symptoms. ADHD may be more often medicated in boys because clinicians may think a prototypical ADHD child is male, and perhaps conduct problems make boys more disruptive in the classroom, leading to boys being more often treated.

Biological membranes in EV biogenesis, stability, uptake, and cargo transfer: an ISEV position paper arising from the ISEV membranes and EVs workshop

Paracrine and endocrine roles have increasingly been ascribed to extracellular vesicles (EVs) generated by multicellular organisms. Central to the biogenesis, content, and function of EVs are their delimiting lipid bilayer membranes. To evaluate research progress on membranes and EVs, the International Society for Extracellular Vesicles (ISEV) conducted a workshop in March 2018 in Baltimore, Maryland, USA, bringing together key opinion leaders and hands-on researchers who were selected on the basis of submitted applications. The workshop was accompanied by two scientific surveys and covered four broad topics: EV biogenesis and release; EV uptake and fusion; technologies and strategies used to study EV membranes; and EV transfer and functional assays. In this ISEV position paper, we synthesize the results of the workshop and the related surveys to outline important outstanding questions about EV membranes and describe areas of consensus. The workshop discussions and survey responses reveal that while much progress has been made in the field, there are still several concepts that divide opinion. Good consensus exists in some areas, including particular aspects of EV biogenesis, uptake and downstream signalling. Areas with little to no consensus include EV storage and stability, as well as whether and how EVs fuse with target cells. Further research is needed in these key areas, as a better understanding of membrane biology will contribute substantially towards advancing the field of extracellular vesicles.

Hypoxia-reoxygenation of primary astrocytes results in a redistribution of mitochondrial size and mitophagy

Astrocytes serve to maintain proper neuronal function and support neuronal viability, but remain largely understudied in research of cerebral ischemia. Astrocytic mitochondria are core participants in the metabolic activity of astrocytes. The objective of this study is to assess astrocyte mitochondrial competence during hypoxia and post-hypoxia reoxygenation and to determine cellular adaptive and pathological changes in the mitochondrial network. We hypothesize that during metabolic distress in astrocytes; mitochondrial networks undergo a shift in fission-fusion dynamics that results in a change in the morphometric state of the entire mitochondrial network. This mitochondrial network shift may be protective during metabolic distress by priming mitochondrial size and facilitating mitophagy. We demonstrated that hypoxia and post-hypoxia reoxygenation of rat primary astrocytes results in a redistribution of mitochondria to smaller sizes evoked by increased mitochondrial fission. Excessive mitochondrial fission corresponded to Drp-1 dephosphorylation at Ser 637, which preceded mitophagy of relatively small mitochondria. Reoxygenation of astrocytes marked the initiation of elevated mitophagic activity primarily reserved to the perinuclear region where a large number of the smallest mitochondria occurred. Although, during hypoxia astrocytic ATP content was severely reduced, after reoxygenation ATP content returned to near normoxic values and these changes mirrored mitochondrial superoxide production. Concomitant with these changes in astrocytic mitochondria, the number of astrocytic extensions declined only after 10-hours post-hypoxic reoxygenation. Overall, we posit a drastic mitochondrial network change that is triggered by a metabolic crisis during hypoxia; these changes are followed by mitochondrial degradation and retraction of astrocytic extensions during reoxygenation.

MicroRNAs and the Genetic Nexus of Brain Aging, Neuroinflammation, Neurodegeneration, and Brain Trauma

Aging is a complex and integrated gradual deterioration of cellular activities in specific organs of the body, which is associated with increased mortality. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, neurovascular disorders, and neurodegenerative diseases. There are nine tentative hallmarks of aging. In addition, several of these hallmarks are increasingly being associated with acute brain injury conditions. In this review, we consider the genes and their functional pathways involved in brain aging as a means of developing new strategies for therapies targeted to the neuropathological processes themselves, but also as targets for many age-related brain diseases. A single microRNA (miR), which is a short, non-coding RNA species, has the potential for targeting many genes simultaneously and, like practically all other cellular processes, genes associated with many features of brain aging and injury are regulated by miRs. We highlight how certain miRs can mediate deregulation of genes involved in neuroinflammation, acute neuronal injury and chronic neurodegenerative diseases. Finally, we review the recent progress in the development of effective strategies to block specific miR functions and discuss future approaches with the prediction that anti-miR drugs may soon be used in the clinic.

Extracellular Vesicles Secreted in Response to Cytokine Exposure Increase Mitochondrial Oxygen Consumption in Recipient Cells

Extracellular vesicles (EVs) are small, membrane-bound nanoparticles released from most, if not all cells, and can carry functionally active cargo (proteins, nucleic acids) which can be taken up by neighboring cells and mediate physiologically relevant effects. In this capacity, EVs are being regarded as novel cell-to-cell communicators, which may play important roles in the progression of neurodegenerative diseases, like Alzheimer’s disease (AD). Aside from the canonical physical hallmarks of this disease [amyloid β (Aβ) plaques, neurofibrillary tangles, and widespread cell death], AD is characterized by chronic neuroinflammation and mitochondrial dysfunction. In the current study, we sought to better understand the role of tumor necrosis factor-alpha (TNF-α), known to be involved in inflammation, in mediating alterations in mitochondrial function and EV secretion. Using an immortalized hippocampal cell line, we observed significant reductions in several parameters of mitochondrial oxygen consumption after a 24-h exposure period to TNF-α. In addition, after TNF-α exposure we also observed significant upregulation of two microRNAs (miRNAs; miR-34a and miR-146a) associated with mitochondrial dysfunction in secreted EVs. Despite this, when naïve cells are exposed to EVs isolated from TNF-α treated cells, mitochondrial respiration, proton leak, and reactive oxygen species (ROS) production are all significantly increased. Collectively these data indicate that a potent proinflammatory cytokine, TNF-α, induces significant mitochondrial dysfunction in a neuronal cell type, in part via the secretion of EVs, which significantly alter mitochondrial activity in recipient cells.

Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles ("MISEV") guidelines for the field in 2014. We now update these "MISEV2014" guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

MiR-34a and stroke: Assessment of non-modifiable biological risk factors in cerebral ischemia

Aging of the nervous system, and the occurrence of age-related brain diseases such as stroke, are associated with changes to a variety of cellular processes controlled by many distinct genes. MicroRNAs (miRNAs), short non-coding functional RNAs that can induce translational repression or site-specific cleavage of numerous target mRNAs, have recently emerged as important regulators of cellular senescence, aging, and the response to neurological insult. Here, we focused on the assessment of the role of miR-34a in stroke. We noted increases in miR-34a expression in the blood of stroke patients as well as in blood and brain of mice subjected to experimental stroke. Our methodical genetic manipulation of miR-34a expression substantially impacted stroke-associated preclinical outcomes and we have in vitro evidence that these changes may be driven at least in part by disruptions to blood brain barrier integrity and mitochondrial oxidative phosphorylation in endothelial cells. Finally, aging, independent of brain injury, appears to be associated with shifts in circulating miRNA profiles. Taken together, these data support a role for miRNAs, and specifically miR-34a, in brain aging and the physiological response to age-related neurological insult, and lay the groundwork for future investigation of this novel therapeutic target.

Educators' experiences of managing students with ADHD: a qualitative study

BACKGROUND

The symptoms of attention-deficit/hyperactivity disorder are associated with difficulty coping with the social, behavioural and academic components of school. Compared with medication and other non-pharmacological treatment, there is less evidence relating to school-based interventions to support children with ADHD. There is additionally an absence of any research focused on the experiences and practices of educators in the UK around how they work with children who are inattentive, impulsive and hyperactive.

METHODS

Forty-two educational practitioners from primary, secondary and alternate provision schools in the UK participated in focus groups or individual interviews that explored (1) their experiences of managing students with ADHD in the classroom and (2) factors that helped and hindered them in this endeavour. Transcripts were analysed using thematic analysis.

RESULTS

Analysis identified six themes: broad strategies, student-centred, inclusive strategies, labelling, medication and relationships. Participants' experiences of managing students with ADHD drew upon a wide range of strategies that typically involved responding to individual needs in an inclusive manner, so individuals with ADHD could access the classroom with their peers. Participants spoke about three factors that helped and hindered managing students with ADHD. Labelling of students with ADHD was reported, with the negative aspects of labelling, such as stigmatization, affecting the classroom. Educators reported mixed experiences regarding the helpfulness of medication; where helpful, it allowed the use of strategies in the classroom. Although students with ADHD were described as having rollercoaster relationships, positive relationships were considered key to the support of children with these difficulties.

CONCLUSIONS

This study suggests that factors such as attitudes towards ADHD, relationships experienced by students with ADHD and other treatments being delivered need to be carefully considered before strategies are put in place in the classroom. This study supports the need for further work on the implementation of evidence-based school interventions for ADHD.

The predictors of persistent DSM-IV disorders in 3-year follow-ups of the British Child and Adolescent Mental Health Surveys 1999 and 2004

BACKGROUND

The identification of the factors that influence the persistence of psychiatric disorder may assist practitioners to focus on young people who are particularly prone to poor outcomes, but population-based samples of sufficient size are rare.

METHOD

This secondary analysis combined data from two large, population-based cross-sectional surveys in Great Britain (1999 and 2004) and their respective follow-ups (2002 and 2007), to study homotypic persistence among the 998 school-age children with psychiatric disorder at baseline. Psychiatric disorder was measured using the Development and Well-Being Assessment applying DSM-IV criteria. Factors relating to the child, family, and the severity and type of psychopathology at baseline were analysed using logistic regression.

RESULTS

Approximately 50% of children with at least one psychiatric disorder were assigned the same diagnostic grouping at 3-year follow-up. Persistent attention-deficit/hyperactivity disorder and anxiety were predicted by poor peer relationship scores. Persistent conduct disorder was predicted by intellectual disability, rented housing, large family size, poor family function and by severer baseline psychopathology scores.

CONCLUSIONS

Homotypic persistence was predicted by different factors for different groups of psychiatric disorders. Experimental research in clinical samples should explore whether these factors also influence response to interventions.

TNF-α and Beyond: Rapid Mitochondrial Dysfunction Mediates TNF-α-Induced Neurotoxicity

This short communication describes our research which demonstrates that TNF-α causes a rapid decline in mitochondrial function, leading to neuronal cell death. As such, this neurotoxic proinflammatory cytokine may play a role in brain damage from stroke and neurodegeneration in chronic conditions such as Alzheimer's disease (AD) and Parkinson's disease. We have extended this initial observation by demonstrating that TNF-α stimulates a microRNA (miR-34a) which we have shown reduces five key proteins in the mitochondrial electron transport chain through base-pair complementarity. miR-34a is increased in affected brain regions of Alzheimer's patients and transgenic AD mouse models. We have further shown that oligomeric amyloid beta 42 (oAβ42) stimulates miR-34a. Collectively, these data suggest that TNF-α, oAβ42, and miR-34a participate in a vicious cycle, resulting in mitochondrial dysfunction, which is critical to the neuropathology of AD.

Effect of indomethacin on blood pressure control during treatment with nitrendipine

This study tested the hypothesis that treatment with a nonsteroidal anti-inflammatory drug will not alter the hypotensive effect of a dihydropyridine calcium channel antagonist. Fifteen essential hypertensives (ages 58-80 years) had a supine diastolic blood pressure (DBP) < 100 mmHg after 4 weeks monotherapy with nitrendipine 5-20 mg twice daily. They entered a double-blind randomised crossover study in which the addition of indomethacin 25 mg three times daily was compared with placebo in treatment phases each of 4 weeks duration. Subjects were seen weekly and measurements in the last 2 weeks of each phase were compared. Supine blood pressure (mean +/- SE) was higher in the indomethacin phase (158 +/- 4/80 +/- 2) than in the placebo phase (154 +/- 4/76 +/- 3) (p < 0.01 for DBP). In 6/15 (40%) of subjects the increase in supine diastolic blood pressure with indomethacin was > 5 mmHg. Plasma urea was also increased in the indomethacin phase: 7.6 +/- 0.6 mmol/l compared with placebo: 6.3 +/- 0.5 mmol/l (p < 0.001). The study has demonstrated that concurrent treatment with the NSAID indomethacin impairs the blood pressure lowering effect of the dihydropyridine calcium channel antagonist nitrendipine. This increase in blood pressure with indomethacin in subjects treated with nitrendipine may represent either an independent pressor effect of indomethacin or a reduced vasodilator prostanoid contribution to the hypotensive effect of nitrendipine. This blood pressure increase may be sufficient to interfere significantly with clinical blood pressure control in some subjects.

Felodipine, metoprolol and their combination compared with placebo in isolated systolic hypertension in the elderly

This study compared with placebo the efficacy and tolerability of optimised doses of felodipine 5-20 mg daily, metoprolol 50-200 mg daily and their combination in subjects 60 years or over with isolated systolic hypertension. The study employed a randomised double-blind crossover design with allocation of treatment order within subjects by Latin squares. For each subject, after a single-blind run-in placebo phase, there were four randomised treatment phases each of six weeks duration, with a dose titration step at three weeks if necessary. Twenty-eight subjects entered the randomised phases of the study and twenty-one completed all four phases--13 male, 8 female (ages: median 71, range 59-85 years). At the end of both the felodipine and metoprolol phases systolic and diastolic pressure were reduced at 2 hours postdose compared with the placebo phase (p < 0.001), the blood pressure reduction with felodipine (-40/-20 mmHg) being greater than that with metoprolol (-15/-9 mmHg) (p < 0.01). Immediately predose (12 hours postdose) there was a persisting reduction of supine systolic blood pressure (-17 mmHg) with felodipine (p < 0.001), but there was no significant effect of metoprolol. At both measurement times the two drugs when in combination had an additive effect on blood pressure. There was a 20% increase in reported symptoms during each of the active treatment phases. Four subjects withdrew during the randomised phases because of probable drug-related adverse events and six subjects required dosage reductions during the felodipine or combination phases.(ABSTRACT TRUNCATED AT 250 WORDS)

Mono- and combination therapy with felodipine or enalapril in elderly patients with systolic hypertension

Using a randomised double-blind crossover design with Latin square allocation of treatments in 20 subjects (7 male, 13 female-ages: 61-87 years) with systolic hypertension, we investigated the efficacy and tolerability of once daily felodipine (extended release) 5-20 mg, enalapril 5-20 mg and their combination compared with placebo in four treatment phases each of 6 weeks duration. During each phase, doses were titrated to achieve a predose clinic supine systolic blood pressure of 140 mmHg or to a predetermined maximum dose. In both the felodipine and combination phases, predose supine and standing systolic and diastolic pressures were significantly reduced compared with the placebo phase (decrease in supine pressure: -13/-5 and -18/-7, respectively). Only predose supine diastolic pressure was significantly reduced (-3 mmHg) compared to placebo in the enalapril phase. In combination the effects of the two drugs on predose blood pressure were additive. There was a 40-60% increase in reported symptoms in the felodipine and combination phases compared with the placebo and enalapril phases. Thus, in elderly subjects with systolic hypertension, felodipine effectively reduces blood pressure throughout the dose interval but with vasodilator adverse effects. In contrast, enalapril is well tolerated but is less effective in reducing blood pressure throughout the whole dose interval.

Diltiazem and atenolol in essential hypertension: additivity of effects on blood pressure and cardiac conduction with combination therapy

In 15 patients with mild to moderate essential hypertension, the effects of diltiazem (120 mg twice daily) were compared with those of atenolol (50 mg once daily), the two drugs in combination, and placebo in a randomized double-blind cross-over study with treatment phases of 4 weeks duration. Blood pressure was reduced in the active treatment phases (supine blood pressure: diltiazem, 172/92 mmHg; atenolol, 172/92 mmHg; diltiazem plus atenolol, 164/88 mmHg; pooled estimate of s.e.m. by analysis of variance = 3/1) compared with placebo (180/101 mmHg). Factorial analysis confirmed fully additive antihypertensive effects of the drugs in combination. The time interval from the beginning of the P wave to the beginning of the QRS complex (P-R interval) was longer during combination therapy (0.184s) compared with either diltiazem (0.175s) or atenolol (0.174s) alone, or placebo (0.164s); s.e.m. by analysis of variance = 0.003. No clinically significant conduction disturbances occurred. Plasma atrial natriuretic peptide was elevated by atenolol but not diltiazem. Thus, in subjects with uncomplicated essential hypertension, diltiazem and atenolol had equal antihypertensive efficacy when used alone, and fully additive effects in combination, on both blood pressure and cardiac conduction.

Lack of effect of fish oil supplementation on blood pressure in treated hypertensives

Fish and fish oils have been reported to reduce blood pressure in normotensives and untreated hypertensives. The present study examined the effect of dietary supplementation with fish oil on blood pressure in 20 treated hypertensives with controlled blood pressures who continued their usual antihypertensive drug treatment throughout. A double-blind, randomized crossover design was used, with two phases, each of 8 weeks' duration. In one phase, subjects took fifteen 1 g fish oil capsules (Lipitac; Reckitt and Colman Pharmaceuticals, Sydney, Australia) daily, and in the other, 15 capsules of identical appearance containing 1 g olive oil daily. There was no difference between the treatment phases for any blood pressure parameter, heart rate or body weight, but blood pressure was lower in both phases compared with pretreatment values. The fasting plasma triglyceride concentration was 30% lower in the fish oil phase (P less than 0.001), but there was no difference between the phases for plasma concentrations of total or high-density lipoprotein (HDL) cholesterol. We conclude that, in treated hypertensives with controlled blood pressures, any additional fall in blood pressure produced by dietary supplementation with fish oil is so small that the requirement for antihypertensive drug therapy is unlikely to be reduced.

Automated non-invasive measurement of cardiac output by the carbon dioxide rebreathing method: comparisons with dye dilution and thermodilution

The accuracy and reproducibility of indirect measurement of cardiac output at rest by the carbon dioxide rebreathing (indirect Fick) method with an automated respiratory analysis system (Gould 9000IV) were compared with simultaneous measurements made in duplicate by dye dilution and thermodilution in 25 patients having cardiac catheterisation studies. Measurements of cardiac output by the carbon dioxide rebreathing method were not significantly different from those obtained with dye dilution (mean difference -0.3 l/min, SD 0.76, 95% confidence interval -0.7 to 0.1). Thermodilution significantly over-estimated cardiac output by a mean of 2.2 l/min or 39% (SD 1.5, 95% confidence interval 1.6 to 2.8) compared with the carbon dioxide rebreathing method and significantly overestimated cardiac output by 1.9 l/min or 31% (SD 1.2, 95% confidence interval 1.2 to 2.5) compared with dye dilution. The reproducibility of measurements of cardiac output in individual patients was satisfactory with the dye dilution method but was poor with carbon dioxide rebreathing and thermodilution. Indirect measurement of resting cardiac output by the Gould 9000IV automated carbon dioxide rebreathing method is more accurate but the variability inherent with this method requires that multiple measurements be taken for each determination. Measurement of cardiac output by the thermodilution method by a commercially available cardiac output computer was not satisfactory because not only was there considerable variability between repeat measurements but the method also consistently overestimated cardiac output compared with the dye dilution method.

Optimal size of cuff bladder for indirect measurement of arterial pressure in adults

This study tested the hypothesis that a sphygmomanometer cuff bladder long enough to encircle the arm in most adults ('obese cuff') would provide a more accurate and precise estimate of intra-arterial pressure than the usual 'standard' cuff bladder. In 53 patients undergoing diagnostic coronary angiography (35 males, 18 females, aged 36-79 years), indirect blood pressure, measured in the left arm with a random-zero sphygmomanometer, was compared with simultaneously measured femoral intra-arterial pressure. Duplicate indirect measurements were made with each of two cuffs containing bladders measuring 39 x 15 cm ('obese') and 23 x 12 cm ('standard'). The obese cuff bladder encircled 80% or more of the arm circumference in all subjects, whereas the standard cuff bladder met this requirement in only 19% of the subjects. For both systolic and diastolic pressure there was marked interindividual variability in the differences between indirect and direct measurements with both cuffs. With the obese cuff there was no systematic error in the diastolic blood pressure measurement. The standard cuff consistently overestimated diastolic pressure by 7.7 +/- 8.3 mmHg (mean +/- s.d.). For both cuffs, the difference between indirect and direct diastolic pressure increased with arm size (P less than 0.05). Both cuffs underestimated systolic blood pressure, the obese cuff by 15.5 +/- 11.7 mmHg and the standard cuff by 7.6 +/- 12.1 mmHg. These systolic blood pressure underestimates were greater at higher blood pressures (P less than 0.01) and with smaller arms (P less than 0.05). Age was not related to measurement error with either cuff.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy of the Takeda TM-2420 ambulatory blood pressure monitor

1. The accuracy of blood pressure measurement with the Takeda TM-2420 ambulatory blood pressure monitor and the TM-2020 data recorder have been assessed by comparison with simultaneous measurements taken using auscultation and direct femoral artery measurements. 2. Systolic blood pressure was underestimated by the TM-2420 by a mean of 10 mmHg (s.d. = 6, 95% confidence interval (CI) = -13 to -7) over the range of pressures measured by auscultation. It was underestimated by 23 mmHg (s.d. = 12, 95% CI = -28 to -18) compared with direct femoral artery measurements. 3. Diastolic pressure measurements were similar to those obtained by auscultation. When compared with direct femoral artery recordings, diastolic pressure was overestimated by about 5 mmHg (s.d. = 4, 95% CI = 3.4-6.6), which is consistent with indirect readings, taken with a 'standard' cuff (inflatable bladder 23 cm X 12 cm). 4. The TM-2420/2020 is thus suitable for ambulatory measurements of blood pressure when diastolic pressure is the criterion of interest.

Transmitral velocities measured by pulsed Doppler in healthy volunteers: effects of acute changes in blood pressure and heart rate

The effect of a two minute cold pressor test on transmitral velocities measured by pulsed Doppler was studied in 11 healthy volunteers. Blood pressure increased significantly during cold immersion but peak atrial and peak early diastolic transmitral velocities and their ratio (A:E) were unchanged. There was no correlation between changes in Doppler variables and changes in calculated mean arterial blood pressure during the test. Heart rate changes were variable and not related to changes in blood pressure. In individual people the change in pulse interval during cold immersion was significantly and inversely correlated with the change in the A:E ratio. The large acute increase in arterial pressure seen during the cold pressor test in normal volunteers had no consistent effect on the transmitral velocity profile although small changes in heart rate were associated with large changes in A:E ratio. The effect of small changes in heart rate may be of considerable importance in determining transmitral velocity profiles. Thus in clinical and experimental studies in which the heart rate is not controlled, Doppler data on transmitral flow should be interpreted with caution.

Neuropeptide Y-like immunoreactivity of plasma during hypoglycaemia in man

Previous studies have demonstrated that plasma Neuropeptide Y-like immunoreactivity (NPY-LI) increases after activation of sympathetic nerves. To test the hypothesis that the adrenal medulla may also be a significant source of circulating plasma NPY-LI and to determine if NPY is co-released with adrenal catecholamines, we have measured the peripheral venous concentrations of NPY-LI, adrenaline and noradrenaline in six patients, before and after induction of hypoglycaemia as part of pituitary function tests that also tested gonadotrophin and thyroid stimulating hormone release. The plasma adrenaline concentration was increased approximately 15 times (p less than 0.05) relative to baseline at 30 mins and remained elevated for the 90 minutes of the study. The plasma concentration of both noradrenaline and NPY-LI remained unchanged. These results failed to demonstrate an increase in the amount of NPY-LI released into the plasma during stimulation of the adrenal medulla with hypoglycaemic stress in man. They do not support significant co-release of NPY with adrenaline from the adrenal medulla in man, nor a physiological role for NPY as an adrenal hormone in human subjects in this situation.

Plasma neuropeptide Y and atrial natriuretic peptide concentrations in man

1. In order to examine the concentration of neuropeptide Y-like immunoreactivity (NPY-LI) and atrial natriuretic peptide (ANP) in the circulation in man, blood was sampled from the iliac vein, the inferior vena cava, the superior vena cava, the pulmonary artery and the femoral artery in 13 patients undergoing cardiac catheterization. 2. Plasma NPY-LI levels were similar at all points sampled and no arteriovenous differences were found. Plasma ANP concentration in the pulmonary artery was greater than in peripheral venous blood but there was a strong correlation between the two. 3. The concentration of NPY-LI and ANP in peripheral venous blood reflects central venous and arterial concentrations.

Automated non-invasive measurement of cardiac output: comparison of electrical bioimpedance and carbon dioxide rebreathing techniques

Two commercial automated, non-invasive systems for estimation of cardiac output were evaluated. Values of cardiac output obtained by electrical bioimpedance cardiography (BoMed NCCOM3 machine) were compared with values derived from an indirect Fick technique that uses carbon dioxide rebreathing (Gould 9000 IV system) during 103 simultaneous measurements made at rest in 19 randomly selected subjects and on exercise in 11 subjects. Cardiac output values obtained with impedance cardiography were significantly correlated with those measured by the indirect Fick method, although there was a wide scatter with over 73% of the readings lying outside the limits defined by the line of identity +/- 20%. This correlation was greatly reduced when stroke volume index was used instead of cardiac output. Indirect Fick results were linearly related to oxygen uptake both at rest and on exercise, while impedance cardiography results did not correlate with oxygen uptake. Impedance cardiography gave consistently lower results for cardiac output than indirect Fick at all levels of exercise. Both machines were easy to use and produced acceptable mean (SE) coefficients of variation (BoMed NCCOM3 7.7 (1.0)%, Gould 9000 IV 10.6 (1.4)%). Further validation is required before either of these machines can be recommended as an alternative to invasive monitoring in clinical practice.

Enalapril and atenolol in essential hypertension: attenuation of hypotensive effects in combination

In 16 patients with essential hypertension the effects of enalapril 20 mg once daily were compared with those of atenolol 50 mg once daily, with the two drugs in combination and with placebo using a double-blind cross-over design with allocation of treatment order by randomised Latin squares. For each patient there were four treatment phases, each of four weeks duration, which together comprised a 2 x 2 factorial experiment. All blood pressure parameters were reduced in the three active treatment phases compared to placebo (p less than 0.001). Supine blood pressures (group means) were 171/97 (placebo), 147/85 (enalapril), 154/84 (atenolol) and 144/78 (enalapril plus atenolol) (S.E.M. +/- 2/+/- 1-ANOVA), and standing blood pressures were 170/105 (placebo), 146/92 (enalapril), 154/92 (atenolol) and 147/86 (enalapril plus atenolol) (S.E.M. +/- 3/+/- 1). In the combination phase there was an additional hypotensive response but the potential fully additive effects of the two agents were attenuated by 30-50%. The mechanism of the attenuated hypotensive effect of the combined agents has not been determined. Plasma atrial natriuretic peptide (ANP) concentration was doubled in the presence of atenolol (P less than 0.01) suggesting that ANP may contribute to the hypotensive effect of the beta-blocker.

Treatment of hypertension with enalapril and hydrochlorothiazide or enalapril and atenolol: contrasts in hypotensive interactions

To determine the nature of the resultant effect on blood pressure when angiotensin converting enzyme (ACE) inhibitors are combined with other hypotensive agents in the treatment of uncomplicated essential hypertension, two randomized, double-blind, crossover trials were conducted. In each trial there were four treatment phases, each 4 weeks in duration, comprising a 2 X 2 factorial experiment. Twenty-one patients completed the first study in which the effects of enalapril (10 mg twice daily) were compared with hydrochlorothiazide (25 mg twice daily), with the two drugs in combination and with placebo. All blood pressure parameters were reduced in the three active treatment phases compared with placebo (P less than 0.001). Enalapril and hydrochlorothiazide were equally effective and in combination their hypotensive effects were fully additive. Sixteen patients completed the second study which compared the effects of enalapril (20 mg daily), atenolol (50 mg daily), the two drugs in combination and placebo. All blood pressure parameters were again reduced in all phases compared with placebo (P less than 0.001). Enalapril and atenolol were also equally effective, but in combination their hypotensive effects were less than fully additive, with attenuation of the potential additive response by 30-50%. These results indicate that a diuretic-ACE inhibitor combination can be expected to have a greater hypotensive effect than a beta-blocker-ACE inhibitor combination. Both hydrochlorothiazide and atenolol increased plasma atrial natriuretic peptide (ANP) concentrations (P less than 0.01), suggesting that ANP could contribute to the hypotensive effects of these two drug classes.

Increases in plasma neuropeptide Y concentrations during sympathetic activation in man

Neuropeptide Y (NPY) coexists with noradrenaline in postganglionic sympathetic neurons. In order to test the hypothesis that NPY may be released along with catecholamines by activation of the sympathoadrenal system we measured plasma NPY-like immunoreactivity (NPY-LI) concentrations during cold pressor test, head up tilt and bicycle exercise in healthy volunteers. All 3 manoeuvres resulted in elevation of blood pressure, heart rate and plasma noradrenaline and adrenaline concentrations. These were accompanied by increases in plasma NPY-LI concentrations on cold pressor test and exercise, but not with head up tilt. The increases in both NPY-LI and catecholamines were greatest with exercise. These findings suggest that NPY is released at the same time as noradrenaline when sympathetic noradrenergic nerves are activated.

Binding isotherms by continuous-flow dynamic dialysis

The classical dynamic dialysis technique for the determination of a protein-ligand binding isotherm has been modified by the introduction of a flow cell in which the dialysate on the sink side of the membrane is continuously eluted with a constant flow of eluting buffer and its ligand concentration measured. This new experimental method is termed continuous-flow dynamic dialysis (CFDD). A transfer function procedure for extracting the binding isotherm from the dialysis data is described. This is a more general technique (requiring only a verifiable assumption of linearity) than that previously used, in which the system was modelled using Fick's first law and which relied on the establishment of quasi-steady state conditions across the membrane. The present analysis uses the Laplace transform to effect deconvolution of the impulse response function of the cell from the dialysis data and, using a Fourier series approach, directly yields numerical data representing the free ligand concentration in equilibrium with the protein-ligand complex. The protein-ligand binding isotherm is obtained in parametric form, with time as the parameter.

Effect of pH on thermal stability of collagen in the dispersed and aggregated states

Thermal stabilities of mature insoluble collagen, salt-precipitated fibrils of acid-soluble collagen and acid-soluble collagen in solution were compared as a function of acid pH. Both insoluble and precipitated collagens showed large parallel destabilization with decrease in pH, whereas the intrinsic stability of individual collagen molecules in dilute solution was comparatively unaffected.

Differential anion effects on thermal stability of collagen in the dispersed and aggregated states

The effects of KCNS and KI on thermal transition temperatures of calf skin collagen molecules in dilute acid solution and precipitated collagen fibrils from the same source were compared as a function of salt concentration and pH. The two salts produced qualitatively similar effects on each collagen form, but the response shown by single collagen molecules in dilute solution differed from that observed for molecular aggregates present in native-type fibrils.

Effect of alcohols and neutral salt on the thermal stability of soluble and precipitated acid-soluble collagen

The effects of mono- and poly-hydric alcohols in the presence of KCl on the intrinsic stability of collagen molecules in dilute acid solution were compared with corresponding solvent and salt effects on the increased stability of the aggregated molecules in salt-precipitated fibrils. Salt addition decreased solubility and increased the thermal stability of fibrils, but progressively decreased the stability of collagen molecules in solution. In contrast, the alcohols enhanced solubility and decreased fibril stability, the effects increasing with solvent hydrocarbon chain length and with decreasing hydroxyl/methylene-group ratio. Molar destabilization of dissolved collagen by alcohols was lower than for fibrils, and at low salt concentration, both ethylene glycol and glycerol were structural stabilizers. Electron-micrograph studies indicated that salt-precipitated fibrils tended to adopt the native aggregation mode, and qualitatively similar solvent effects were observed in insoluble collagens. Implications of the experimental findings are discussed in terms of a model in which electrostatic and apolar interactions mainly govern the excess of stability in collagen fibrils whereas intrinsic stability of single molecules is a function of polar interactions and polypeptide-chain rigidity.

Effect of compounds of the urea-guanidinium class on renaturation and thermal stability of acid-soluble collagen

The effects of guanidinium salts in decreasing the renaturation rate and lowering the thermal stability of acid-soluble calf-skin collagen have been compared with those of formamide and urea. With the exception of guanidinium sulphate at higher concentrations, no qualitative differences were apparent in the effects of these perturbants, which thus differed only in molar activity. Activity variation in the guanidinium salts reflected a net effect resulting from additivity of cation and anion contributions. As observed in other protein systems, lyotropic activity increased in the series formamide<urea<guanidinium ion, and in the guanidinium salts in the anion order fluoride<sulphate<chloride<bromide<nitrate<iodide. Low activities of guanidinium fluoride and sulphate were attributable to counter-effects of the anions, which acted as structural stabilizers. Changes in renaturation kinetics induced by either temperature or added perturbants appeared to conform with the Flory-Weaver model for the collagen transition. Additivity and non-specificity of the observed effects are discussed with particular reference to a common mechanism involving weak, non-saturated binding of perturbants at protein peptide groups.