S.D. COX, C.M. MANN, J.L. MARKHAM, H.C. BELL, J.E. GUSTAFSON, J.R. WARMINGTON and S.G. WYLLIE.2000.The essential oil of Melaleuca alternifolia (tea tree) exhibits broad‐spectrum antimicrobial ...activity. Its mode of action against the Gram‐negative bacterium Escherichia coli AG100, the Gram‐positive bacterium Staphylococcus aureus NCTC 8325, and the yeast Candida albicans has been investigated using a range of methods. We report that exposing these organisms to minimum inhibitory and minimum bactericidal/fungicidal concentrations of tea tree oil inhibited respiration and increased the permeability of bacterial cytoplasmic and yeast plasma membranes as indicated by uptake of propidium iodide. In the case of E. coli and Staph. aureus, tea tree oil also caused potassium ion leakage. Differences in the susceptibility of the test organisms to tea tree oil were also observed and these are interpreted in terms of variations in the rate of monoterpene penetration through cell wall and cell membrane structures. The ability of tea tree oil to disrupt the permeability barrier of cell membrane structures and the accompanying loss of chemiosmotic control is the most likely source of its lethal action at minimum inhibitory levels.
The characteristics of pneumococcal carriage vary between infants and adults. Host immune factors have been shown to contribute to these age-specific differences, but the role of pathogen sequence ...variation is currently less well-known. Identification of age-associated pathogen genetic factors could leadto improved vaccine formulations. We therefore performed genome sequencing in a large carriage cohort of children and adults and combined this with data from an existing age-stratified carriage study. We compiled a dictionary of pathogen genetic variation, including serotype, strain, sequence elements, single-nucleotide polymorphisms (SNPs), and clusters of orthologous genes (COGs) for each cohort - all of which were used in a genome-wide association with host age. Age-dependent colonization showed weak evidence of being heritable in the first cohort (
= 0.10, 95% CI 0.00-0.69) and stronger evidence in the second cohort (
= 0.56, 95% CI 0.23-0.87). We found that serotypes and genetic background (strain) explained a proportion of the heritability in the first cohort (
= 0.07, 95% CI 0.04-0.14 and
= 0.06, 95% CI 0.03-0.13) and the second cohort (
= 0.11, 95% CI 0.05-0.21 and
= 0.20, 95% CI 0.12-0.31). In a meta-analysis of these cohorts, we found one candidate association (p=1.2 × 10
) upstream of an accessory Sec-dependent serine-rich glycoprotein adhesin. Overall, while we did find a small effect of pathogen genome variation on pneumococcal carriage between child and adult hosts, this was variable between populations and does not appear to be caused by strong effects of individual genes. This supports proposals for adaptive future vaccination strategies that are primarily targeted at dominant circulating serotypes and tailored to the composition of the pathogen populations.
The p53 gene has been implicated as a tumour suppressor, with mutations occurring in many carcinomas, such as colon, breast and lung. We have sequenced exons 5, 7 and 8 containing conserved gene ...regions in the only available differentiated thyroid follicular carcinoma cell line and found a mutation at position 273, Arg---His, with no normal allele present. The same mutation was also present in DNA from the tumour of origin. However immunohistochemical analysis of 129 human thyroid tumours using a panel of p53 antibodies was unequivocally negative. Southern blotting in 20 cases failed to demonstrate any deletion or rearrangement, and direct genomic sequencing of 20 carcinomas showed normal DNA sequence for exons 5, 7 and 8. Thus p53 abnormalities may not be important in human thyroid carcinogenesis, in contrast to colon, breast and lung. However, the FTC 133 cell line was only established after 132 unsuccessful attempts with other differentiated thyroid follicular tumours. Since this line and the corresponding tumour of origin have a p53 mutation, we propose that p53 mutation may confer on thyroid follicular tumour cells the ability to grow in culture. This has potential applications for the future development of thyroid carcinoma cell lines.
A major challenge in neurobiology is to understand mechanisms underlying human neuronal diversification. Motor neurons (MNs) represent a diverse collection of neuronal subtypes, displaying ...differential vulnerability in different human neurodegenerative diseases. The ability to manipulate cell subtype diversification is critical to establish accurate, clinically relevant in vitro disease models. Retinoid signalling contributes to caudal precursor specification and subsequent MN subtype diversification. Here we investigate the necessity for retinoic acid in motor neurogenesis from human embryonic stem cells. We show that activin/nodal signalling inhibition, followed by sonic hedgehog agonist treatment, is sufficient for MN precursor specification, which occurs even in the presence of retinoid pathway antagonists. Importantly, precursors mature into HB9/ChAT-expressing functional MNs. Furthermore, retinoid-independent motor neurogenesis results in a ground state biased to caudal, medial motor columnar identities from which a greater retinoid-dependent diversity of MNs, including those of lateral motor columns, can be selectively derived in vitro.
BACKGROUND AND PURPOSE
Developmental switches in NMDA receptor subunit expression have been inferred from studies of GluN2 expression levels, changes in kinetics of glutamatergic synaptic currents ...and sensitivity of NMDA receptor‐mediated currents to selective GluN2B antagonists. Here we use TCN 213, a novel GluN2A‐selective antagonist to identify the presence of this subunit in functional NMDA receptors in developing cortical neurones.
EXPERIMENTAL APPROACH
Two‐electrode voltage‐clamp (TEVC) recordings were made from Xenopus laevis oocytes to determine the pharmacological activity of TCN 213 at recombinant NMDA receptors. TCN 213 antagonism was studied in cultures of primary cortical neurones, assessing the NMDA receptor dependency of NMDA‐induced excitotoxicity and monitoring developmental switches in NMDA receptor subunit composition.
KEY RESULTS
TCN 213 antagonism of GluN1/GluN2A NMDA receptors was dependent on glycine but independent of glutamate concentrations in external recording solutions. Antagonism by TCN 213 was surmountable and gave a Schild plot with unity slope. TCN 213 block of GluN1/GluN2B NMDA receptor‐mediated currents was negligible. In cortical neurones, at a early developmental stage predominantly expressing GluN2B‐containing NMDA receptors, TCN 213 failed to antagonize NMDA receptor‐mediated currents or to prevent GluN2B‐dependent, NMDA‐induced excitoxicity. In older cultures (DIV 14) or in neurones transfected with GluN2A subunits, TCN 213 antagonized NMDA‐evoked currents. Block by TCN 213 of NMDA currents inversely correlated with block by ifenprodil, a selective GluN2B antagonist.
CONCLUSIONS AND IMPLICATIONS
TCN 213 selectively blocked GluN1/GluN2A over GluN1/GluN2B NMDA receptors allowing direct dissection of functional NMDA receptors and pharmacological profiling of developmental changes in native NMDA receptor subunit composition.
Although aberrant methylation of key genes in the progression of colorectal neoplasia has been reported, no model-based analysis of the incremental changes through the intermediate adenoma stage has ...been described. In addition, the biological drivers for these methylation changes have yet to be defined. Linear mixed-effects modelling was used in this study to understand the onset and patterns of the methylation changes of SFRP2, IGF2 DMR0, H19, LINE-1 and a CpG island methylator phenotype (CIMP) marker panel, and they were correlated with DNA methyltransferase 3B (DNMT3B) levels of expression in a sample set representative of colorectal neoplastic progression.
Methylation of the above CpG islands was measured using quantitative pyrosequencing assays in 261 tissue samples. This included a prospective collection of 44 colectomy specimens with concurrent normal mucosa, adenoma and invasive cancer tissues. Tissue microarrays from a subset of 64 cases were used for immunohistochemical analysis of DNMT3B expression.
It is shown that the onset and pattern of methylation changes during colorectal neoplastic progression are locus dependent. The CIMP marker RUNX3 was the earliest CpG island showing significant change, followed by the CIMP markers NEUROG1 and CACNA1G at the hyperplastic polyp stage. SFRP2 and IGF2 DMR0 showed significant methylation changes at the adenomatous polyp stage, followed by the CIMP markers CDKN2A and hMLH1 at the adenocarcinoma stage. DNMT3B levels of immunohistochemical expression increased significantly (p < 0.001) from normal to hyperplastic and from adenomatous polyps to carcinoma samples. DNMT3B expression correlated positively with SFRP2 methylation (r = 0.42, p < 0.001, 95% CI 0.25 to 0.56), but correlated negatively with IGF2 DMR0 methylation (r = 0.26, p = 0.01, 95% CI -0.45 to -0.05). A subset of the CIMP panel (NEUROG1, CACNA1G and CDKN2A) positively correlated with DNMT3B levels of expression (p < 0.05).
Hierarchical epigenetic alterations occur at transition points during colorectal neoplastic progression. These cumulative changes are closely correlated with a gain of DNMT3B expression, suggesting a causal relationship.
This is the sixth annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With ...Treatment Recommendations. This summary addresses the most recently published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. Topics covered by systematic reviews include cardiopulmonary resuscitation during transport; approach to resuscitation after drowning; passive ventilation; minimizing pauses during cardiopulmonary resuscitation; temperature management after cardiac arrest; use of diagnostic point-of-care ultrasound during cardiac arrest; use of vasopressin and corticosteroids during cardiac arrest; coronary angiography after cardiac arrest; public-access defibrillation devices for children; pediatric early warning systems; maintaining normal temperature immediately after birth; suctioning of amniotic fluid at birth; tactile stimulation for resuscitation immediately after birth; use of continuous positive airway pressure for respiratory distress at term birth; respiratory and heart rate monitoring in the delivery room; supraglottic airway use in neonates; prearrest prediction of in-hospital cardiac arrest mortality; basic life support training for likely rescuers of high-risk populations; effect of resuscitation team training; blended learning for life support training; training and recertification for resuscitation instructors; and recovery position for maintenance of breathing and prevention of cardiac arrest. Members from 6 task forces have assessed, discussed, and debated the quality of the evidence using Grading of Recommendations Assessment, Development, and Evaluation criteria and generated consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections, and priority knowledge gaps for future research are listed.
Coronavirus disease 2019 (COVID-19) has had a substantial impact on the incidence of cardiac arrest and survival. The challenge is to find the correct balance between the risk to the rescuer when ...undertaking cardiopulmonary resuscitation (CPR) on a person with possible COVID-19 and the risk to that person if CPR is delayed. These guidelines focus specifically on patients with suspected or confirmed COVID-19. The guidelines include the delivery of basic and advanced life support in adults and children and recommendations for delivering training during the pandemic. Where uncertainty exists treatment should be informed by a dynamic risk assessment which may consider current COVID-19 prevalence, the person’s presentation (e.g. history of COVID-19 contact, COVID-19 symptoms), likelihood that treatment will be effective, availability of personal protective equipment (PPE) and personal risks for those providing treatment. These guidelines will be subject to evolving knowledge and experience of COVID-19. As countries are at different stages of the pandemic, there may some international variation in practice.
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