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result(s) for
"Oliver, Gina C"
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Exploring Microbial Growth of a Model Extremophile, Archaeoglobus Fulgidus, at Elevated Pressures
by
Oliver, Gina C
in
Geobiology
2019
Deep-sea vent and subsurface microorganisms are metabolically diverse and often display unique adaptive strategies that operate under elevated pressure conditions. However, because high hydrostatic pressure (HHP) laboratory cultivation has not been widely adopted, knowledge of how these microorganisms function in native high-pressure environments is limited. To explore how elevated pressures affect the metabolism and physiology of deep-sea and subsurface microorganisms, growth of a model extremophile, Archaeoglobus fulgidus (type strain VC16), was investigated up to 98 MPa in batch cultures for both chemoorganoheterotrophic and chemolithoautotrophic metabolisms. A. fulgidus is an anaerobic, hyperthermophilic sulfate reducing archaeon, first isolated from a shallow marine vent but has been commonly identified in high-pressure marine environments (to 2-4 km below sea level, 20-40 MPa), including deep-sea hydrothermal vents, deep geothermal wells, and deep oil reservoirs. In heterotrophic HHP cultivation experiments, exponential growth was observed up to 60 MPa. Cell densities were comparable from 0.1-40 MPa, while lower cell densities were observed at 50 MPa and 60 MPa and growth was inhibited at 70 MPa. A. fulgidus displayed both piezotolerance and moderate piezophily under certain heterotrophic HHP conditions. In autotrophic HHP conditions, A. fulgidus displayed piezotolerance with similar growth rates and maximum cell densities observed at up to 40 MPa and little to no growth was observed at 60 MPa. A. fulgidus biofilm production was observed in certain heterotrophic conditions from 0.1-50 MPa under HHP batch cultivation conditions due to both low calcium concentrations in the growth medium and the presence of a stainless steel needle that created a nucleation site. This suggests that biofilm production here was a response to growth medium chemistry and surface area, and was not related to the elevated pressure conditions. Here, A. fulgidus was shown to grow, and in some cases also produce biofilm, over a range of elevated pressure conditions. To the extent of our knowledge, piezotolerance to HHP for both heterotrophic and autotrophic metabolisms have not been previously measured for a single species. A. fulgidus’ metabolic plasticity and capacity for biofilm production reflects adaptive mechanisms that lend insight into how this species thrives in extreme and fluctuating environments.
Dissertation
Reduction in mobility and COVID-19 transmission
2021
In response to the COVID-19 pandemic, countries have sought to control SARS-CoV-2 transmission by restricting population movement through social distancing interventions, thus reducing the number of contacts. Mobility data represent an important proxy measure of social distancing, and here, we characterise the relationship between transmission and mobility for 52 countries around the world. Transmission significantly decreased with the initial reduction in mobility in 73% of the countries analysed, but we found evidence of decoupling of transmission and mobility following the relaxation of strict control measures for 80% of countries. For the majority of countries, mobility explained a substantial proportion of the variation in transmissibility (median adjusted R-squared: 48%, interquartile range - IQR - across countries [27–77%]). Where a change in the relationship occurred, predictive ability decreased after the relaxation; from a median adjusted R-squared of 74% (IQR across countries [49–91%]) pre-relaxation, to a median adjusted R-squared of 30% (IQR across countries [12–48%]) post-relaxation. In countries with a clear relationship between mobility and transmission both before and after strict control measures were relaxed, mobility was associated with lower transmission rates after control measures were relaxed indicating that the beneficial effects of ongoing social distancing behaviours were substantial.
Social distancing policies aiming to reduce COVID-19 transmission have been reflected in reductions in human mobility. Here, the authors show that reduced mobility is correlated with decreased transmission, but that this relationship weakened over time as social distancing measures were relaxed.
Journal Article
State-level tracking of COVID-19 in the United States
by
Bradley, Valerie C.
,
Xi, Xiaoyue
,
Hawryluk, Iwona
in
631/114/2397
,
631/326/596/4130
,
692/308/174
2020
As of 1st June 2020, the US Centres for Disease Control and Prevention reported 104,232 confirmed or probable COVID-19-related deaths in the US. This was more than twice the number of deaths reported in the next most severely impacted country. We jointly model the US epidemic at the state-level, using publicly available death data within a Bayesian hierarchical semi-mechanistic framework. For each state, we estimate the number of individuals that have been infected, the number of individuals that are currently infectious and the time-varying reproduction number (the average number of secondary infections caused by an infected person). We use changes in mobility to capture the impact that non-pharmaceutical interventions and other behaviour changes have on the rate of transmission of SARS-CoV-2. We estimate that
R
t
was only below one in 23 states on 1st June. We also estimate that 3.7% [3.4%–4.0%] of the total population of the US had been infected, with wide variation between states, and approximately 0.01% of the population was infectious. We demonstrate good 3 week model forecasts of deaths with low error and good coverage of our credible intervals.
High numbers of COVID-19-related deaths have been reported in the United States, but estimation of the true numbers of infections is challenging. Here, the authors estimate that on 1 June 2020, 3.7% of the US population was infected with SARS-CoV-2, and 0.01% was infectious, with wide variation by state.
Journal Article
Estimating the effects of non-pharmaceutical interventions on COVID-19 in Europe
by
Donnelly, Christl A.
,
Zhu, Harrison
,
Coupland, Helen
in
631/326/596/4130
,
692/699/1785
,
692/699/255/2514
2020
Following the detection of the new coronavirus
1
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its spread outside of China, Europe has experienced large epidemics of coronavirus disease 2019 (COVID-19). In response, many European countries have implemented non-pharmaceutical interventions, such as the closure of schools and national lockdowns. Here we study the effect of major interventions across 11 European countries for the period from the start of the COVID-19 epidemics in February 2020 until 4 May 2020, when lockdowns started to be lifted. Our model calculates backwards from observed deaths to estimate transmission that occurred several weeks previously, allowing for the time lag between infection and death. We use partial pooling of information between countries, with both individual and shared effects on the time-varying reproduction number (
R
t
). Pooling allows for more information to be used, helps to overcome idiosyncrasies in the data and enables more-timely estimates. Our model relies on fixed estimates of some epidemiological parameters (such as the infection fatality rate), does not include importation or subnational variation and assumes that changes in
R
t
are an immediate response to interventions rather than gradual changes in behaviour. Amidst the ongoing pandemic, we rely on death data that are incomplete, show systematic biases in reporting and are subject to future consolidation. We estimate that—for all of the countries we consider here—current interventions have been sufficient to drive
R
t
below 1 (probability
R
t
< 1.0 is greater than 99%) and achieve control of the epidemic. We estimate that across all 11 countries combined, between 12 and 15 million individuals were infected with SARS-CoV-2 up to 4 May 2020, representing between 3.2% and 4.0% of the population. Our results show that major non-pharmaceutical interventions—and lockdowns in particular—have had a large effect on reducing transmission. Continued intervention should be considered to keep transmission of SARS-CoV-2 under control.
Modelling based on pooled data from 11 European countries indicates that non-pharmaceutical interventions—particularly lockdowns—have had a marked effect on SARS-CoV-2 transmission, driving the reproduction number of the infection below 1.
Journal Article
Response to COVID-19 in South Korea and implications for lifting stringent interventions
by
Baguelin, Marc
,
Watson, Oliver J.
,
FitzJohn, Richard G.
in
Bayes Theorem
,
Bayesian analysis
,
Betacoronavirus
2020
Background
After experiencing a sharp growth in COVID-19 cases early in the pandemic, South Korea rapidly controlled transmission while implementing less stringent national social distancing measures than countries in Europe and the USA. This has led to substantial interest in their “test, trace, isolate” strategy. However, it is important to understand the epidemiological peculiarities of South Korea’s outbreak and characterise their response before attempting to emulate these measures elsewhere.
Methods
We systematically extracted numbers of suspected cases tested, PCR-confirmed cases, deaths, isolated confirmed cases, and numbers of confirmed cases with an identified epidemiological link from publicly available data. We estimated the time-varying reproduction number,
R
t
, using an established Bayesian framework, and reviewed the package of interventions implemented by South Korea using our extracted data, plus published literature and government sources.
Results
We estimated that after the initial rapid growth in cases,
R
t
dropped below one in early April before increasing to a maximum of 1.94 (95%CrI, 1.64–2.27) in May following outbreaks in Seoul Metropolitan Region. By mid-June,
R
t
was back below one where it remained until the end of our study (July 13th). Despite less stringent “lockdown” measures, strong social distancing measures were implemented in high-incidence areas and studies measured a considerable national decrease in movement in late February. Testing the capacity was swiftly increased, and protocols were in place to isolate suspected and confirmed cases quickly; however, we could not estimate the delay to isolation using our data. Accounting for just 10% of cases, individual case-based contact tracing picked up a relatively minor proportion of total cases, with cluster investigations accounting for 66%.
Conclusions
Whilst early adoption of testing and contact tracing is likely to be important for South Korea’s successful outbreak control, other factors including regional implementation of strong social distancing measures likely also contributed. The high volume of testing and the low number of deaths suggest that South Korea experienced a small epidemic relative to other countries. Caution is needed in attempting to replicate the South Korean response in populations with larger more geographically widespread epidemics where finding, testing, and isolating cases that are linked to clusters may be more difficult.
Journal Article
Adipose Mesenchymal Stromal Cell‐Based Therapy for Severe Osteoarthritis of the Knee: A Phase I Dose‐Escalation Trial
by
Fleury, Sandrine
,
Lisignoli, Gina
,
Bourin, Philippe
in
Adipose mesenchymal stromal cells
,
Adipose Tissue - cytology
,
Adipose Tissue - transplantation
2016
This phase I clinical trial evaluated the safety and clinical efficacy of adipose‐derived stromal cells (ASCs) in osteoarthritis. Eighteen patients with severe knee osteoarthritis were treated with a single intra‐articular injection of autologous ASCs at low (2 × 106 cells), medium (10 × 106), or high (50 × 106) doses (n = 6 each). After 6 months, no serious adverse events were reported, and patients treated with low‐dose ASCs significantly improved in pain and function. Osteoarthritis (OA) is the most widespread musculoskeletal disorder in adults. It leads to cartilage damage associated with subchondral bone changes and synovial inflammation, causing pain and disability. The present study aimed at evaluating the safety of a dose‐escalation protocol of intra‐articular injected adipose‐derived stromal cells (ASCs) in patients with knee OA, as well as clinical efficacy as secondary endpoint. A bicentric, uncontrolled, open phase I clinical trial was conducted in France and Germany with regulatory agency approval for ASC expansion procedure in both countries. From April 2012 to December 2013, 18 consecutive patients with symptomatic and severe knee OA were treated with a single intra‐articular injection of autologous ASCs. The study design consisted of three consecutive cohorts (six patients each) with dose escalation: low dose (2 × 106 cells), medium dose (10 × 106), and high dose (50 × 106). The primary outcome parameter was safety evaluated by recording adverse events throughout the trial, and secondary parameters were pain and function subscales of the Western Ontario and McMaster Universities Arthritis Index. After 6 months of follow‐up, the procedure was found to be safe, and no serious adverse events were reported. Four patients experienced transient knee joint pain and swelling after local injection. Interestingly, patients treated with low‐dose ASCs experienced significant improvements in pain levels and function compared with baseline. Our data suggest that the intra‐articular injection of ASCs is a safe therapeutic alternative to treat severe knee OA patients. A placebo‐controlled double‐blind phase IIb study is being initiated to assess clinical and structural efficacy. Significance Although this phase I study included a limited number of patients without a placebo arm, it showed that local injection of autologous adipose‐derived stem cells was safe and well tolerated in patients with knee osteoarthritis. This study also provides encouraging preliminary evidence of efficacy. Larger and controlled long‐term studies are now mandatory to confirm whether this new strategy of cell therapy can improve pain and induce structural benefit in osteoarthritis.
Journal Article
Comparison of molecular testing strategies for COVID-19 control: a mathematical modelling study
by
Ainslie, Kylie
,
Baguelin, Marc
,
Volz, Erik
in
Antibodies
,
Asymptomatic
,
Asymptomatic Infections
2020
WHO has called for increased testing in response to the COVID-19 pandemic, but countries have taken different approaches and the effectiveness of alternative strategies is unknown. We aimed to investigate the potential impact of different testing and isolation strategies on transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
We developed a mathematical model of SARS-CoV-2 transmission based on infectiousness and PCR test sensitivity over time since infection. We estimated the reduction in the effective reproduction number (R) achieved by testing and isolating symptomatic individuals, regular screening of high-risk groups irrespective of symptoms, and quarantine of contacts of laboratory-confirmed cases identified through test-and-trace protocols. The expected effectiveness of different testing strategies was defined as the percentage reduction in R. We reviewed data on the performance of antibody tests reported by the Foundation for Innovative New Diagnostics and examined their implications for the use of so-called immunity passports.
If all individuals with symptoms compatible with COVID-19 self-isolated and self-isolation was 100% effective in reducing onwards transmission, self-isolation of symptomatic individuals would result in a reduction in R of 47% (95% uncertainty interval [UI] 32–55). PCR testing to identify SARS-CoV-2 infection soon after symptom onset could reduce the number of individuals needing to self-isolate, but would also reduce the effectiveness of self-isolation (around 10% would be false negatives). Weekly screening of health-care workers and other high-risk groups irrespective of symptoms by use of PCR testing is estimated to reduce their contribution to SARS-CoV-2 transmission by 23% (95% UI 16–40), on top of reductions achieved by self-isolation following symptoms, assuming results are available at 24 h. The effectiveness of test and trace depends strongly on coverage and the timeliness of contact tracing, potentially reducing R by 26% (95% UI 14–35) on top of reductions achieved by self-isolation following symptoms, if 80% of cases and contacts are identified and there is immediate testing following symptom onset and quarantine of contacts within 24 h. Among currently available antibody tests, performance has been highly variable, with specificity around 90% or lower for rapid diagnostic tests and 95–99% for laboratory-based ELISA and chemiluminescent assays.
Molecular testing can play an important role in prevention of SARS-CoV-2 transmission, especially among health-care workers and other high-risk groups, but no single strategy will reduce R below 1 at current levels of population immunity. Immunity passports based on antibody tests or tests for infection face substantial technical, legal, and ethical challenges.
UK Medical Research Council.
Journal Article
Combining volunteers and primary care teamwork to support health goals and needs of older adults: a pragmatic randomized controlled trial
by
Lamarche, Larkin
,
Papaioannou, Alexandra
,
Agarwal, Gina
in
Accidental Falls - prevention & control
,
Aged
,
Aged - psychology
2019
The Health TAPESTRY (Health Teams Advancing Patient Experience: STRengthening QualitY) intervention was designed to improve primary care teamwork and promote optimal aging. We evaluated the effectiveness of Health TAPESTRY in attaining goals of older adults (e.g., physical activity, productivity, social connection, medical status) and other outcomes.
We conducted a pragmatic randomized controlled trial between January and October 2015 in a primary care practice in Hamilton, Ontario. Older adults were randomized (1:1) to Health TAPESTRY (n = 158) or control (n = 154). Trained community volunteers gathered information on people’s goals, needs and risks in their homes, using electronic forms. Interprofessional primary care teams reviewed summaries and addressed issues. Participants reported goal attainment (primary outcome), self-efficacy, quality of life, optimal aging, social support, empowerment, physical activity, falls, and access to and comprehensiveness of the health system. We determined use of health care resources through chart audit.
There were no differences between groups in goal attainment or many other patient-reported outcome and experience assessments at 6 months. More primary care visits took place in the intervention versus control group over 6 months (mean ± standard deviation [SD] 4.93±3.86 v. 3.50 ± 3.53; difference of 1.52 [95% confidence interval (CI) 0.84 to 2.19]). The odds of having 1 or more hospital admission were lower for the intervention group (odds ratio [OR] 0.44 [95% CI 0.20 to 0.95]).
Health TAPESTRY did not improve the primary outcome of goal attainment but showed signals of shifting care from reactive to active preventive care. Further evaluation will help in understanding effective components, costs and consequences of the intervention. Trial registration:ClinicalTrials.gov, no. NCT02283723
Journal Article
Evidence of initial success for China exiting COVID-19 social distancing policy after achieving containment
2020
Background : The COVID-19 epidemic was declared a Global Pandemic by WHO on 11 March 2020. By 24 March 2020, over 440,000 cases and almost 20,000 deaths had been reported worldwide. In response to the fast-growing epidemic, which began in the Chinese city of Wuhan, Hubei, China imposed strict social distancing in Wuhan on 23 January 2020 followed closely by similar measures in other provinces. These interventions have impacted economic productivity in China, and the ability of the Chinese economy to resume without restarting the epidemic was not clear. Methods : Using daily reported cases from mainland China and Hong Kong SAR, we estimated transmissibility over time and compared it to daily within-city movement, as a proxy for economic activity. Results : Initially, within-city movement and transmission were very strongly correlated in the five mainland provinces most affected by the epidemic and Beijing. However, that correlation decreased rapidly after the initial sharp fall in transmissibility. In general, towards the end of the study period, the correlation was no longer apparent, despite substantial increases in within-city movement. A similar analysis for Hong Kong shows that intermediate levels of local activity were maintained while avoiding a large outbreak. At the very end of the study period, when China began to experience the re-introduction of a small number of cases from Europe and the United States, there is an apparent up-tick in transmission. Conclusions: Although these results do not preclude future substantial increases in incidence, they suggest that after very intense social distancing (which resulted in containment), China successfully exited its lockdown to some degree. Elsewhere, movement data are being used as proxies for economic activity to assess the impact of interventions. The results presented here illustrate how the eventual decorrelation between transmission and movement is likely a key feature of successful COVID-19 exit strategies.
Journal Article
A multi-centre, double-blind, 12-week, randomized, placebo-controlled trial to assess the efficacy of adjunctive N-Acetylcysteine for treatment-resistant PTSD: a study protocol
by
Kalivas, Peter
,
Maier, Alice
,
Redston, Suzy
in
Acetylcysteine
,
Acetylcysteine - therapeutic use
,
Adjunctive therapy
2020
Background
Most patients with Posttraumatic Stress Disorder (PTSD) suffer residual symptoms following first-line treatment. Oxidative stress has been implicated in the pathophysiology of PTSD. N-acetylcysteine (NAC) is a precursor of the brain’s primary antioxidant, glutathione, and may diminish oxidative cellular damage. An 8-week pilot study of NAC in veterans with PTSD found that symptoms were significantly reduced in the NAC group compared to placebo. This study aims to confirm these findings with a larger sample in a double-blind, placebo-controlled trial to further explore the efficacy of NAC as an adjunctive therapy in treatment-resistant PTSD.
Methods
A multicentre, randomised, double-blind, placebo-controlled trial for adult patients who still meet criteria for PTSD following first-line treatment. The intervention comprises either NAC as a fixed dose regime of 2.7 g/day (900 mg three times daily) administered orally for 12 weeks, or placebo. Standard care for PTSD will continue in addition, including other pharmacotherapies. Detailed clinical data will be collected at randomisation and weeks 4, 8, 12, 16, and 64 post-randomisation, with self-report measures completed weekly from baseline to 16 weeks and at 64 weeks post-randomisation. Blood-based biomarkers will be collected at baseline and 12 weeks to assess the mechanism of effect. The primary outcome measure will be change in Clinician-Administered PTSD Scale for DSM-5 at 12 weeks compared with baseline. Secondary outcomes will be change in quality of life, depression, anxiety, substance use and craving, and somatic symptoms. With 126 completed participants (63 per arm), the study is powered at 80% to detect a true difference in the primary outcome measure using a two-tailed analysis with alpha = 0.05, beta = 0.2.
Discussion
This is the first multicentre, double blind, randomised, placebo-controlled trial of adjunctive NAC for treatment-resistant PTSD. NAC has an established safety profile, is readily available and easy to administer, and has a favourable tolerability profile, therefore making it an attractive adjunctive therapy. Inclusion of blood analyses to assess potential target engagement biomarkers of oxidative stress and neuroinflammation may help gauge the biological mechanisms of effect of NAC.
Trial registration
ACTRN12618001784202, retrospectively registered 31/10/2018, URL:
http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376004
.
Journal Article