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1.
Nature ; 600(7889): 506-511, 2021 12.
Article in English | MEDLINE | ID: mdl-34649268

ABSTRACT

The evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021.


Subject(s)
COVID-19/epidemiology , COVID-19/virology , Genome, Viral/genetics , Genomics , SARS-CoV-2/genetics , Amino Acid Substitution , COVID-19/transmission , England/epidemiology , Epidemiological Monitoring , Humans , Molecular Epidemiology , Mutation , Quarantine/statistics & numerical data , SARS-CoV-2/classification , Spatio-Temporal Analysis , Spike Glycoprotein, Coronavirus/genetics
2.
Nature ; 593(7858): 266-269, 2021 05.
Article in English | MEDLINE | ID: mdl-33767447

ABSTRACT

The SARS-CoV-2 lineage B.1.1.7, designated variant of concern (VOC) 202012/01 by Public Health England1, was first identified in the UK in late summer to early autumn 20202. Whole-genome SARS-CoV-2 sequence data collected from community-based diagnostic testing for COVID-19 show an extremely rapid expansion of the B.1.1.7 lineage during autumn 2020, suggesting that it has a selective advantage. Here we show that changes in VOC frequency inferred from genetic data correspond closely to changes inferred by S gene target failures (SGTF) in community-based diagnostic PCR testing. Analysis of trends in SGTF and non-SGTF case numbers in local areas across England shows that B.1.1.7 has higher transmissibility than non-VOC lineages, even if it has a different latent period or generation time. The SGTF data indicate a transient shift in the age composition of reported cases, with cases of B.1.1.7 including a larger share of under 20-year-olds than non-VOC cases. We estimated time-varying reproduction numbers for B.1.1.7 and co-circulating lineages using SGTF and genomic data. The best-supported models did not indicate a substantial difference in VOC transmissibility among different age groups, but all analyses agreed that B.1.1.7 has a substantial transmission advantage over other lineages, with a 50% to 100% higher reproduction number.


Subject(s)
COVID-19/transmission , COVID-19/virology , Phylogeny , SARS-CoV-2/classification , SARS-CoV-2/pathogenicity , Adolescent , Adult , Age Distribution , Aged , Aged, 80 and over , Basic Reproduction Number , COVID-19/diagnosis , COVID-19/epidemiology , Child , Child, Preschool , England/epidemiology , Evolution, Molecular , Genome, Viral/genetics , Humans , Infant , Infant, Newborn , Middle Aged , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/analysis , Spike Glycoprotein, Coronavirus/genetics , Time Factors , Young Adult
3.
J Chem Phys ; 160(8)2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38391017

ABSTRACT

Microcanonical unimolecular rate theory is applied to Shirhatti and Wodtke's recent supersonic molecular beam experiments examining the activated dissociative chemisorption of HCl on Au(111). A precursor mediated microcanonical trapping (PMMT) model (where the surface vibrates and HCl rotations, vibration, and translation directed along the surface normal are treated as active degrees of freedom) gave dissociative sticking coefficient predictions that are several orders of magnitude higher than experimental values but in good accord with prior quantum and molecular dynamics simulations. Density functional theory (DFT) electronic structure calculations using the Perdew-Burke-Ernzerhof (PBE) functional served to fix the vibrational frequencies of the reactive transition state and the threshold energy for dissociation, E0 = 72.9 kJ/mol. To explore the possibilities of varying threshold energy, coupling to phonons, and dynamics, a three-parameter [E0, s, ɛn] dynamically biased (d-) PMMT model was fit to the experiments. A dynamical bias was introduced using an efficiency, ɛn, of normal translational energy to contribute to the active exchangeable energy capable of promoting reactivity. To achieve the low sticking probabilities observed in experiment, severe normal translational energy dampening (ɛn → 0.26) was imposed, leading to a large vibrational efficacy of ηv = εv/εn = 3.85. The optimal threshold energy for dissociation was E0 = 30.88 kJ/mol, some 40 kJ/mol below the PBE-DFT prediction, and the optimal number of Au surface oscillators was s = 1. The d-PMMT modeling indicates that HCl/Au(111) reactivity can be consistent with electronically adiabatic passage across a relatively low and late transition state that dynamically disfavors normal translational energy.

4.
Skin Res Technol ; 30(4): e13672, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38591218

ABSTRACT

BACKGROUND: Hyaluronic acid (HA) is a widely used active cosmetic ingredient. Its multiple skin care benefits are modulated by its molecular weight. Low molecular weight (LMW) HA can penetrate the skin, but high molecular weight (HMW) HA remains at the surface. Here, we assessed how vectorization of HMW HA with bentonite clay-achieved with an innovative technology-enhances its cosmetic and hydrating properties. MATERIALS AND METHODS: The two HA forms were applied to skin explants; their penetration and smoothing effects were monitored by Raman spectroscopy and scanning electron microscopy. The two forms were biochemically characterised by chromatography, enzyme sensitivity assays, and analysis of Zeta potential. Cosmetics benefits such as, the smoothing effect of vectorised-HA was assessed in ex vivo experiments on skin explants. A placebo-controlled clinical study was finally conducted applying treatments for 28 days to analyse the final benefits in crow's feet area. RESULTS: Raman spectroscopy analysis revealed native HMW HA to accumulate at the surface of skin explants, whereas vectorised HMW HA was detected in deeper skin layers. This innovative vectorisation process changed the zeta potential of vectorised HMW HA, being then more anionic and negative without impacting the biochemical structure of native HA. In terms of cosmetic benefits, following application of vectorised HMW HA ex vivo, the skin's surface was visibly smoother. This smoothing was clinically confirmed, with a significant reduction in fine lines. CONCLUSION: The development of innovative process vectorising HMW HA allowed HMW HA penetration in the skin. This enhanced penetration extends the clinical benefits of this iconic cosmetic ingredient.


Subject(s)
Hyaluronic Acid , Skin Aging , Humans , Hyaluronic Acid/pharmacology , Hyaluronic Acid/chemistry , Clay , Molecular Weight , Skin
5.
Epidemiol Infect ; 151: e169, 2023 09 20.
Article in English | MEDLINE | ID: mdl-37726109

ABSTRACT

Whole-genome sequencing (WGS) information has played a crucial role in the SARS-CoV-2 (COVID-19) pandemic by providing evidence about variants to inform public health policy. The purpose of this study was to assess the representativeness of sequenced cases compared with all COVID-19 cases in England, between March 2020 and August 2021, by demographic and socio-economic characteristics, to evaluate the representativeness and utility of these data in epidemiological analyses. To achieve this, polymerase chain reaction (PCR)-confirmed COVID-19 cases were extracted from the national laboratory system and linked with WGS data. During the study period, over 10% of COVID-19 cases in England had WGS data available for epidemiological analysis. With sequencing capacity increasing throughout the period, sequencing representativeness compared to all reported COVID-19 cases increased over time, allowing for valuable epidemiological analyses using demographic and socio-economic characteristics, particularly during periods with emerging novel SARS-CoV-2 variants. This study demonstrates the comprehensiveness of England's sequencing throughout the COVID-19 pandemic, rapidly detecting variants of concern, and enabling representative epidemiological analyses to inform policy.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , SARS-CoV-2/genetics , Pandemics , England/epidemiology
7.
Molecules ; 27(6)2022 Mar 21.
Article in English | MEDLINE | ID: mdl-35335373

ABSTRACT

Products designed to cleanse the skin commonly do so through surfactant action, which leads to the lowering of the surface tension of the skin to facilitate the removal of dirt from its surface. Skin cleansers generally come in one of two types: soap-based and synthetic detergents, or syndets. While the latter can effectively maintain the native skin structure, function and integrity, the former tends to negatively affect the skin by causing barrier disruption, lipid dissolution and pH alteration. Despite this, soap is still often preferred, possibly due to the negative connotations around anything that is not perceived as 'natural'. It is, therefore, important that the science behind cleansers, especially those designed for the maintenance of healthy skin and the management of common skin conditions such as eczema, be understood by both formulators and end-users. Here, we carefully weigh the advantages and disadvantages of the different types of surfactant-the key ingredient(s) in skin cleansers-and provide insight into surfactants' physicochemical properties, biological activity and potential effects. Fine-tuning of the complex characteristics of surfactants can successfully lead to an 'optimal' skin cleanser that can simultaneously be milder in nature, highly effective and beneficial, and offer minimal skin interference and environmental impact.


Subject(s)
Detergents , Soaps , Detergents/chemistry , Skin , Skin Care , Soaps/chemistry , Surface-Active Agents/pharmacology
8.
Neuroimage ; 238: 118270, 2021 09.
Article in English | MEDLINE | ID: mdl-34144160

ABSTRACT

Pharmacological MRI (phMRI) studies seek to capture changes in brain haemodynamics in response to a drug. This provides a methodological platform for the evaluation of novel therapeutics, and when applied to disease states, may provide diagnostic or mechanistic information pertaining to common brain disorders such as dementia. Changes to brain perfusion and blood-cerebrospinal fluid barrier (BCSFB) function can be probed, non-invasively, by arterial spin labelling (ASL) and blood-cerebrospinal fluid barrier arterial spin labelling (BCSFB-ASL) MRI respectively. Here, we introduce a method for simultaneous recording of pharmacological perturbation of brain perfusion and BCSFB function using interleaved echo-time ASL, applied to the anesthetized mouse brain. Using this approach, we capture an exclusive decrease in BCSFB-mediated delivery of arterial blood water to ventricular CSF, following anti-diuretic hormone, vasopressin, administration. The commonly used vasodilatory agent, CO2, induced similar increases (~21%) in both cortical perfusion and the BCSFB-ASL signal. Furthermore, we present evidence that caffeine administration triggers a marked decrease in BCSFB-mediated labelled water delivery (41%), with no significant changes in cortical perfusion. Finally, we demonstrate a marked decrease in the functional response of the BCSFB to, vasopressin, in the aged vs adult brain. Together these data, the first of such kind, highlight the value of this translational approach to capture simultaneous and differential pharmacological modulation of vessel tone at the blood brain barrier and BCSFB and how this relationship may be modified in the ageing brain.


Subject(s)
Blood-Brain Barrier/diagnostic imaging , Brain/diagnostic imaging , Cerebrovascular Circulation/drug effects , Magnetic Resonance Imaging/methods , Animals , Blood-Brain Barrier/drug effects , Brain/drug effects , Caffeine/pharmacology , Male , Mice , Spin Labels , Vasoconstrictor Agents/pharmacology , Vasopressins/pharmacology
9.
Magn Reson Med ; 85(1): 326-333, 2021 01.
Article in English | MEDLINE | ID: mdl-32910547

ABSTRACT

PURPOSE: A fundamental goal in the drive to understand and find better treatments for dementia is the identification of the factors that render the aging brain vulnerable to neurodegenerative disease. Recent evidence indicates the integrity of the blood-brain barrier (BBB) to be an important component of functional failure underlying age-related cognitive decline. Practical and sensitive measurement is necessary, therefore, to support diagnostic and therapeutic strategies targeted at maintaining BBB integrity in aging patients. Here, we investigated changes in BBB permeability to endogenous blood water in the aging brain. METHODS: A multiple-echo-time arterial spin-labeling MRI technique, implemented on a 9.4T Bruker imaging system, was applied to 7- and 27-month-old mice to measure changes in water permeability across the BBB with aging. RESULTS: We observed that BBB water permeability was 32% faster in aged mice. This occurred along with a 2.1-fold increase in mRNA expression of aquaporin-4 water channels and a 7.1-fold decrease in mRNA expression of α-syntrophin protein, which anchors aquaporin-4 to the BBB. CONCLUSION: Age-related changes to water permeability across the BBB can be captured using noninvasive noncontrast MRI techniques.


Subject(s)
Blood-Brain Barrier , Neurodegenerative Diseases , Aging , Animals , Blood-Brain Barrier/diagnostic imaging , Brain/diagnostic imaging , Humans , Magnetic Resonance Imaging , Mice , Permeability , Water
10.
Conserv Biol ; 35(5): 1388-1395, 2021 10.
Article in English | MEDLINE | ID: mdl-33484006

ABSTRACT

Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.


Asignación de Recursos para la Conservación, Resiliencia de Poblaciones Pequeñas y la Falacia del Triaje de Conservación Resumen Algunos métodos de priorización de la conservación están basados en el supuesto de que las necesidades de la conservación superan a los actuales recursos y que no todas las especies pueden ser conservadas; por lo tanto, se necesita un esquema de triaje (esto es, cuando el sistema está abrumado, las especies deben dividirse en tres grupos con base en su probabilidad de supervivencia y los esfuerzos deben enfocarse en aquellas especies dentro del grupo con las mejores probabilidades de supervivencia y a aquellas en el grupo sin probabilidades de supervivencia o aquellas en el grupo que no necesita esfuerzos especializados para su conservación se les deben reducir o negar los esfuerzos de conservación) para dirigir la asignación de recursos. Discutimos que esta estrategia para la toma de decisiones no es apropiada porque los recursos no están tan limitados como se asume con frecuencia y tampoco es evidente que existan especies que no puedan ser conservadas. Por ejemplo, tan sólo un tamaño poblacional pequeño no es suficiente para condenar a una especie a la extinción; contamos con ejemplos en plantas, reptiles, aves y mamíferos. Aunque actualmente todos los recursos dedicados a la conservación de todas las especies amenazadas son insuficientes, los recursos económicos mundiales son vastos y se podrían dedicar mayores recursos a la conservación de especies. El marco de trabajo político para la conservación de especies ha mejorado, con iniciativas como los Objetivos de Desarrollo Sustentable de la ONU y otros acuerdos internacionales, el financiamiento de mecanismos como el Fondo para el Medio Ambiente Mundial, y el surgimiento de muchas organizaciones no gubernamentales mediante programas de subsidios pequeños hábiles y de respuesta rápida. Para que un sistema de priorización no permita las extinciones, las cero extinciones deben ser un objetivo explícito del sistema. La extinción no es inevitable y no debería ser aceptable. El objetivo de cero extinciones inducidas por humanos es imperativo dada la irreversibilidad de la pérdida de especies.


Subject(s)
Conservation of Natural Resources , Triage , Animals , Biodiversity , Endangered Species , Extinction, Biological , Mammals , Resource Allocation
11.
Brain ; 143(8): 2576-2593, 2020 08 01.
Article in English | MEDLINE | ID: mdl-32705145

ABSTRACT

The glymphatic system, that is aquaporin 4 (AQP4) facilitated exchange of CSF with interstitial fluid (ISF), may provide a clearance pathway for protein species such as amyloid-ß and tau, which accumulate in the brain in Alzheimer's disease. Further, tau protein transference via the extracellular space, the compartment that is cleared by the glymphatic pathway, allows for its neuron-to-neuron propagation, and the regional progression of tauopathy in the disorder. The glymphatic system therefore represents an exciting new target for Alzheimer's disease. Here we aim to understand the involvement of glymphatic CSF-ISF exchange in tau pathology. First, we demonstrate impaired CSF-ISF exchange and AQP4 polarization in a mouse model of tauopathy, suggesting that this clearance pathway may have the potential to exacerbate or even induce pathogenic accumulation of tau. Subsequently, we establish the central role of AQP4 in the glymphatic clearance of tau from the brain; showing marked impaired glymphatic CSF-ISF exchange and tau protein clearance using the novel AQP4 inhibitor, TGN-020. As such, we show that this system presents as a novel druggable target for the treatment of Alzheimer's disease, and possibly other neurodegenerative diseases alike.


Subject(s)
Alzheimer Disease/metabolism , Aquaporin 4/metabolism , Brain/metabolism , Glymphatic System/metabolism , tau Proteins/metabolism , Alzheimer Disease/pathology , Animals , Brain/pathology , Cerebrospinal Fluid/metabolism , Disease Models, Animal , Extracellular Fluid/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic
12.
Dermatol Ther ; 34(4): e14970, 2021 07.
Article in English | MEDLINE | ID: mdl-33984185

ABSTRACT

The dysfunctional skin barrier in eczema patients may be attributed to decreased levels of ceramides in the stratum corneum. The aim of this study was to determine whether a two-part system consisting of a ceramide-dominant physiological lipid-based moisturizing cream and cleanser could ameliorate the signs and symptoms of moderate eczema in adults over 28 days compared to placebo. Assessments were conducted at baseline and every 7 days thereafter. Eczema area severity index score decreased significantly across all time points in both groups compared to baseline (P < .0001), however, this decrease was not significant between groups at day 28 (P = .7804). In contrast, transepidermal water loss and skin hydration significantly improved over time in the active group, while it either stayed the same or worsened in the placebo group (P = .0342 and P < .0001, respectively). There was no difference in the use of mometasone furoate as rescue medication over time between groups (P = .1579). Dermatology life quality index scores improved significantly in both groups (P < .0001), with no difference between groups (P = .5256). However, patient satisfaction was greater in the active compared to the placebo group for several parameters including relief of itch, dry skin, skin softness and smoothness (all P < .05). No patients withdrew from the study due to adverse events (AEs) and there were no serious AEs. The ceramide-dominant moisturizing cream and cleanser safely restores skin permeability and improves the signs and symptoms of eczema in adults.


Subject(s)
Ceramides , Eczema , Adult , Eczema/diagnosis , Eczema/drug therapy , Humans , Permeability , Pruritus , Skin Cream
13.
Australas J Dermatol ; 62(4): e510-e515, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34477217

ABSTRACT

BACKGROUND: Clinical trial recruitment is challenging for investigators who often overestimate the pool of qualified, willing subjects. Moreover, there is a paucity of literature, particularly in dermatology, regarding recruitment and the comparative success of advertising strategies. METHODS: Both 'traditional' (physician referral, newspaper and radio advertisements, letterbox drops, posters/flyers, word-of-mouth) and 'modern' (patient recruitment services, social media, Google advertisements, websites, email) recruitment methods were used to enrol 100 patients (>18 years) diagnosed with moderate eczema for a randomised, double-blind, placebo-controlled trial investigating the efficacy and safety of a topical eczema treatment over 4 weeks. The relationships between recruitment method and patient age, sex, race, study completion and costs were analysed. RESULTS: The majority of patients recruited were young, with millennials and Gen Z comprising 77% of the study population. Both traditional and modern recruitment methods were equally successful in recruiting younger patients, with older patients predominately recruited by traditional methods. Eighty per cent more men were recruited by traditional compared to modern methods, whilst 67% more women than men were recruited by modern methods. Recruitment method neither appeared to be influenced by race, nor did it effect whether patients completed the study. Costs per enrolment were similar for both methods. CONCLUSIONS: This study shows that despite the high proportion of young patients and the rising popularity of social media and increased internet use, a combination of both traditional and modern recruitment methods was required to successfully meet the trial enrolment target of 100 adult patients with moderate eczema.


Subject(s)
Eczema/drug therapy , Patient Selection , Randomized Controlled Trials as Topic , Administration, Topical , Adolescent , Adult , Advertising , Age Factors , Aged , Australia , Double-Blind Method , Female , Humans , Male , Mass Media , Middle Aged , Social Media , Young Adult
14.
Neuroimage ; 223: 117271, 2020 12.
Article in English | MEDLINE | ID: mdl-32835824

ABSTRACT

Down Syndrome is a chromosomal disorder that affects the development of cerebellar cortical lobules. Impaired neurogenesis in the cerebellum varies among different types of neuronal cells and neuronal layers. In this study, we developed an imaging analysis framework that utilizes gadolinium-enhanced ex vivo mouse brain MRI. We extracted the middle Purkinje layer of the mouse cerebellar cortex, enabling the estimation of the volume, thickness, and surface area of the entire cerebellar cortex, the internal granular layer, and the molecular layer in the Tc1 mouse model of Down Syndrome. The morphometric analysis of our method revealed that a larger proportion of the cerebellar thinning in this model of Down Syndrome resided in the inner granule cell layer, while a larger proportion of the surface area shrinkage was in the molecular layer.


Subject(s)
Cerebellar Cortex/diagnostic imaging , Cerebellar Cortex/pathology , Down Syndrome/diagnostic imaging , Down Syndrome/pathology , Magnetic Resonance Imaging/methods , Neurons/pathology , Animals , Contrast Media , Disease Models, Animal , Gadolinium/administration & dosage , Image Enhancement/methods , Male , Mice, Inbred C57BL , Staining and Labeling/methods
15.
Bioscience ; 70(4): 330-342, 2020 Apr 01.
Article in English | MEDLINE | ID: mdl-32284631

ABSTRACT

Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one-third of all vertebrate species. This biodiversity is declining dramatically: Globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but coordinated action to reverse the decline is lacking. We present an Emergency Recovery Plan to bend the curve of freshwater biodiversity loss. Priority actions include accelerating implementation of environmental flows; improving water quality; protecting and restoring critical habitats; managing the exploitation of freshwater ecosystem resources, especially species and riverine aggregates; preventing and controlling nonnative species invasions; and safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on Biological Diversity and the Sustainable Development Goals and roles for national and international state and nonstate actors.

16.
Neuroimage ; 188: 515-523, 2019 03.
Article in English | MEDLINE | ID: mdl-30557661

ABSTRACT

There is currently a lack of non-invasive tools to assess water transport in healthy and pathological brain tissue. Aquaporin-4 (AQP4) water channels are central to many water transport mechanisms, and emerging evidence also suggests that AQP4 plays a key role in amyloid-ß (Aß) clearance, possibly via the glymphatic system. Here, we present the first non-invasive technique sensitive to AQP4 channels polarised at the blood-brain interface (BBI). We apply a multiple echo time (multi-TE) arterial spin labelling (ASL) MRI technique to the mouse brain to assess BBI water permeability via calculation of the exchange time (Texw), the time for magnetically labelled intravascular water to exchange across the BBI. We observed a 31% increase in exchange time in AQP4-deficient (Aqp4-/-) mice (452 ±â€¯90 ms) compared to their wild-type counterparts (343 ±â€¯91 ms) (p = 0.01), demonstrating the sensitivity of the technique to the lack of AQP4 water channels. More established, quantitative MRI parameters: arterial transit time (δa), cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) detected no significant changes with the removal of AQP4. This clinically relevant tool may be crucial to better understand the role of AQP4 in water transport across the BBI, as well as clearance of proteins in neurodegenerative conditions such as Alzheimer's disease.


Subject(s)
Aquaporin 4/physiology , Biological Transport/physiology , Blood-Brain Barrier/physiology , Body Water , Glymphatic System/physiology , Magnetic Resonance Imaging/methods , Neuroimaging/methods , Animals , Blood-Brain Barrier/diagnostic imaging , Female , Glymphatic System/diagnostic imaging , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Spin Labels
17.
J Neurochem ; 148(1): 136-156, 2019 01.
Article in English | MEDLINE | ID: mdl-30269333

ABSTRACT

Histone hypoacetylation is associated with dopaminergic neurodegeneration in Parkinson's disease (PD), because of an imbalance in the activities of the enzymes responsible for histone (de)acetylation. Correction of this imbalance, with histone deacetylase (HDAC) inhibiting agents, could be neuroprotective. We therefore hypothesize that nicotinamide, being a selective inhibitor of HDAC class III as well as having modulatory effects on mitochondrial energy metabolism, would be neuroprotective in the lactacystin rat model of PD, which recapitulates the formation of neurotoxic accumulation of altered proteins within the substantia nigra to cause progressive dopaminergic cell death. Rats received nicotinamide for 28 days, starting 7 days after unilateral injection of the irreversible proteasome inhibitor, lactacystin, into the substantia nigra. Longitudinal motor behavioural testing and structural magnetic resonance imaging were used to track changes in this model of PD, and assessment of nigrostriatal integrity, histone acetylation and brain gene expression changes post-mortem used to quantify nicotinamide-induced neuroprotection. Counterintuitively, nicotinamide dose-dependently exacerbated neurodegeneration of dopaminergic neurons, behavioural deficits and structural brain changes in the lactacystin-lesioned rat. Nicotinamide treatment induced histone hyperacetylation and over-expression of numerous neurotrophic and anti-apoptotic factors in the brain, yet failed to result in neuroprotection, rather exacerbated dopaminergic pathology. These findings highlight the importance of inhibitor specificity within HDAC isoforms for therapeutic efficacy in PD, demonstrating the contrasting effects of HDAC class III inhibition upon cell survival in this animal model of the disease. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.


Subject(s)
Dopaminergic Neurons/drug effects , Histone Deacetylase Inhibitors/pharmacology , Nerve Degeneration/pathology , Niacinamide/pharmacology , Parkinsonian Disorders/pathology , Acetylation/drug effects , Acetylcysteine/analogs & derivatives , Acetylcysteine/toxicity , Animals , Cell Death/drug effects , Disease Models, Animal , Dopaminergic Neurons/pathology , Male , Parkinsonian Disorders/chemically induced , Rats , Rats, Sprague-Dawley
18.
J Hepatol ; 70(1): 40-49, 2019 01.
Article in English | MEDLINE | ID: mdl-30201461

ABSTRACT

BACKGROUND & AIMS: Neuronal function is exquisitely sensitive to alterations in the extracellular environment. In patients with hepatic encephalopathy (HE), accumulation of metabolic waste products and noxious substances in the interstitial fluid of the brain is thought to result from liver disease and may contribute to neuronal dysfunction and cognitive impairment. This study was designed to test the hypothesis that the accumulation of these substances, such as bile acids, may result from reduced clearance from the brain. METHODS: In a rat model of chronic liver disease with minimal HE (the bile duct ligation [BDL] model), we used emerging dynamic contrast-enhanced MRI and mass-spectroscopy techniques to assess the efficacy of the glymphatic system, which facilitates clearance of solutes from the brain. Immunofluorescence of aquaporin-4 (AQP4) and behavioural experiments were also performed. RESULTS: We identified discrete brain regions (olfactory bulb, prefrontal cortex and hippocampus) of altered glymphatic clearance in BDL rats, which aligned with cognitive/behavioural deficits. Reduced AQP4 expression was observed in the olfactory bulb and prefrontal cortex in HE, which could contribute to the pathophysiological mechanisms underlying the impairment in glymphatic function in BDL rats. CONCLUSIONS: This study provides the first experimental evidence of impaired glymphatic flow in HE, potentially mediated by decreased AQP4 expression in the affected regions. LAY SUMMARY: The 'glymphatic system' is a newly discovered brain-wide pathway that facilitates clearance of various substances that accumulate in the brain due to its activity. This study evaluated whether the function of this system is altered in a model of brain dysfunction that occurs in cirrhosis. For the first time, we identified that the clearance of substances from the brain in cirrhosis is reduced because this clearance system is defective. This study proposes a new mechanism of brain dysfunction in patients with cirrhosis and provides new targets for therapy.


Subject(s)
Aquaporin 4/metabolism , Brain/metabolism , Cerebrospinal Fluid/metabolism , Glymphatic System/metabolism , Hepatic Encephalopathy/metabolism , Animals , Brain/diagnostic imaging , Brain/physiopathology , Disease Models, Animal , Glymphatic System/physiopathology , Hepatic Encephalopathy/diagnosis , Hepatic Encephalopathy/physiopathology , Intracranial Pressure , Magnetic Resonance Imaging , Male , Rats , Rats, Sprague-Dawley
19.
J Med Virol ; 89(3): 502-507, 2017 03.
Article in English | MEDLINE | ID: mdl-27486960

ABSTRACT

Cytomegalovirus (CMV) is the most common congenital infection in humans and a leading cause of sensorineural hearing loss. Ganciclovir (6 mg/kg twice daily for 42 days) has been shown to reduce hearing deterioration and is used in clinical practice. Vaccines and passive administration of antibody are being evaluated in randomized controlled trials in allograft candidates, women of childbearing age, and pregnant women with primary CMV infection. To help define genetic variation in each of the targets of these therapeutic interventions, we amplified and sequenced genes UL97 (site utilised for ganciclovir phosphorylation), UL55 (glycoprotein B (gB) vaccine target) and UL128, UL130, and UL131a (specific monoclonal antibody targets). Serial blood, saliva, and urine samples (total 120) obtained from nine infants with symptomatic congenital CMV treated with 42 days' ganciclovir were analyzed. All samples tested were UL97 wild type at baseline and none developed mutations during treatment, showing no selection of resistance. The prevalences of UL55 genotypes were 28% gB1, 22% gB2, 1% gB3, and mixed in 20% samples. No mutations were noted in UL128-131a. Phylogenetic tree analysis showed that sequences with variations were found in multiple body sites of individual patients, so there was no evidence of body site compartmentalization of particular strains of CMV. The significance of these results for changes in diagnostic practices and therapeutic interventions against CMV are discussed. J. Med. Virol. 89:502-507, 2017. © 2016 Wiley Periodicals, Inc.


Subject(s)
Antiviral Agents/therapeutic use , Cytomegalovirus Infections/congenital , Cytomegalovirus Infections/drug therapy , Cytomegalovirus/genetics , Cytomegalovirus/isolation & purification , Genetic Loci , Genetic Variation , Antibodies, Monoclonal/therapeutic use , Antibodies, Viral/therapeutic use , Blood/virology , Cluster Analysis , Cytomegalovirus/classification , Drug Resistance, Viral , Ganciclovir/therapeutic use , Humans , Infant , Mutation , Phylogeny , Saliva/virology , Urine/virology , Viral Proteins/genetics
20.
Bioscience ; 67(10): 919-927, 2017 Oct 01.
Article in English | MEDLINE | ID: mdl-29599539

ABSTRACT

Freshwater biodiversity is highly threatened and is decreasing more rapidly than its terrestrial or marine counterparts; however, freshwaters receive less attention and conservation investment than other ecosystems do. The diverse group of freshwater megafauna, including iconic species such as sturgeons, river dolphins, and turtles, could, if promoted, provide a valuable tool to raise awareness and funding for conservation. We found that freshwater megafauna inhabit every continent except Antarctica, with South America, Central Africa, and South and Southeast Asia being particularly species rich. Freshwater megafauna co-occur with up to 93% of mapped overall freshwater biodiversity. Fifty-eight percent of the 132 megafauna species included in the study are threatened, with 84% of their collective range falling outside of protected areas. Of all threatened freshwater species, 83% are found within the megafauna range, revealing the megafauna's capacity as flagship and umbrella species for fostering freshwater conservation.

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