ORCID Profile
0000-0002-8290-6425
Current Organisations
University of Sydney
,
Amsterdam UMC location AMC
,
Stichting HIV Monitoring
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Publications
Combination Antiretroviral Therapy and the Risk of Myocardial Infarction
Publisher: Massachusetts Medical Society
Date: 20-11-2003
DOI: 10.1056/NEJMOA030218
Linkage and retention in HCV care for HIV ‐infected populations: early data from the DAA era
Publisher: Wiley
Date: 04-2018
DOI: 10.1002/JIA2.25051
Restrictions for reimbursement of interferon-free direct-acting antiviral drugs for HCV infection in Europe
Publisher: Elsevier BV
Date: 02-2018
A subarcsec localized fast radio burst with a significant host galaxy dispersion measure contribution
Publisher: Oxford University Press (OUP)
Date: 24-06-2023
Abstract: We present the discovery of FRB 20210410D with the MeerKAT radio interferometer in South Africa, as part of the MeerTRAP commensal project. FRB 20210410D has a dispersion measure DM = 578.78 ± 2 ${\\rm pc \\, cm^{-3}}$ and was localized to subarcsec precision in the 2 s images made from the correlation data products. The localization enabled the association of the FRB with an optical galaxy at z = 0.1415, which when combined with the DM places it above the 3σ scatter of the Macquart relation. We attribute the excess DM to the host galaxy after accounting for contributions from the Milky Way’s interstellar medium and halo, and the combined effects of the intergalactic medium and intervening galaxies. This is the first FRB that is not associated with a dwarf galaxy to exhibit a likely large host galaxy DM contribution. We do not detect any continuum radio emission at the FRB position or from the host galaxy down to a 3σ rms of 14.4 $\\mu$Jy beam−1. The FRB has a scattering delay of $29.4^{+2.8}_{-2.7}$ ms at 1 GHz, and exhibits candidate subpulses in the spectrum, which hint at the possibility of it being a repeating FRB. Although not constraining, we note that this FRB has not been seen to repeat in 7.28 h at 1.3 GHz with MeerKAT, 3 h at 2.4 GHz with Murriyang, and 5.7 h at simultaneous 2.3 GHz and 8.4 GHz observations with the Deep Space Network. We encourage further follow-up to establish a possible repeating nature.
Autoantibodies neutralizing type I IFNs are present in ~4% of uninfected individuals over 70 years old and account for ~20% of COVID-19 deaths
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-08-2021
DOI: 10.1126/SCIIMMUNOL.ABL4340
Abstract: Autoantibodies neutralizing type I IFNs increase in prevalence over 60 years of age and underlie about 20% of all fatal COVID-19 cases.
Development of a definition for Rapid Progression (RP) of renal function in HIV-positive persons: the D:A:D study
Publisher: Springer Science and Business Media LLC
Date: 25-03-2014
Simultaneous multi-telescope observations of FRB 121102
Publisher: Oxford University Press (OUP)
Date: 29-06-2020
Abstract: We present 11 detections of FRB 121102 in ∼3 h of observations during its ‘active’ period on the 10th of 2019 September. The detections were made using the newly deployed MeerTRAP system and single pulse detection pipeline at the MeerKAT radio telescope in South Africa. Fortuitously, the Nançay radio telescope observations on this day overlapped with the last hour of MeerKAT observations and resulted in four simultaneous detections. The observations with MeerKAT’s wide band receiver, which extends down to relatively low frequencies (900–1670 MHz usable L-band range), have allowed us to get a detailed look at the complex frequency structure, intensity variations, and frequency-dependent sub-pulse drifting. The drift rates we measure for the full-band and sub-banded data are consistent with those published between 600 and 6500 MHz with a slope of −0.147 ± 0.014 ms−1. Two of the detected bursts exhibit fainter ‘precursors’ separated from the brighter main pulse by ∼28 and ∼34 ms. A follow-up multi-telescope c aign on the 6th and 8th of 2019 October to better understand these frequency drifts and structures over a wide and continuous band was undertaken. No detections resulted, indicating that the source was ‘inactive’ over a broad frequency range during this time.
Predictive Performance of Cardiovascular Disease Risk Prediction Algorithms in People Living With HIV
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 15-08-2019
X-linked recessive TLR7 deficiency in ~1% of men under 60 years old with life-threatening COVID-19
Publisher: American Association for the Advancement of Science (AAAS)
Date: 12-08-2021
DOI: 10.1126/SCIIMMUNOL.ABL4348
Abstract: TLR7 and plasmacytoid dendritic cells are essential for type I IFN–dependent immunity to SARS-CoV-2 in the lungs.
Inborn errors of type I IFN immunity in patients with life-threatening COVID-19
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-10-2020
Abstract: The immune system is complex and involves many genes, including those that encode cytokines known as interferons (IFNs). In iduals that lack specific IFNs can be more susceptible to infectious diseases. Furthermore, the autoantibody system d ens IFN response to prevent damage from pathogen-induced inflammation. Two studies now examine the likelihood that genetics affects the risk of severe coronavirus disease 2019 (COVID-19) through components of this system (see the Perspective by Beck and Aksentijevich). Q. Zhang et al. used a candidate gene approach and identified patients with severe COVID-19 who have mutations in genes involved in the regulation of type I and III IFN immunity. They found enrichment of these genes in patients and conclude that genetics may determine the clinical course of the infection. Bastard et al. identified in iduals with high titers of neutralizing autoantibodies against type I IFN-α2 and IFN-ω in about 10% of patients with severe COVID-19 pneumonia. These autoantibodies were not found either in infected people who were asymptomatic or had milder phenotype or in healthy in iduals. Together, these studies identify a means by which in iduals at highest risk of life-threatening COVID-19 can be identified. Science , this issue p. eabd4570 , p. eabd4585 see also p. 404
Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study
Publisher: Public Library of Science (PLoS)
Date: 31-03-2015
Periodic Radio Emission from the T8 Dwarf WISE J062309.94–045624.6
Publisher: American Astronomical Society
Date: 07-2023
Abstract: We present the detection of rotationally modulated, circularly polarized radio emission from the T8 brown dwarf WISE J062309.94−045624.6 between 0.9 and 2.0 GHz. We detected this high-proper-motion ultracool dwarf with the Australian SKA Pathfinder in 1.36 GHz imaging data from the Rapid ASKAP Continuum Survey. We observed WISE J062309.94−045624.6 to have a time and frequency averaged Stokes I flux density of 4.17 ± 0.41 mJy beam −1 , with an absolute circular polarization fraction of 66.3% ± 9.0%, and calculated a specific radio luminosity of L ν ∼ 10 14.8 erg s −1 Hz −1 . In follow-up observations with the Australian Telescope Compact Array and MeerKAT we identified a multipeaked pulse structure, used dynamic spectra to place a lower limit of B 0.71 kG on the dwarf’s magnetic field, and measured a P = 1.912 ± 0.005 hr periodicity, which we concluded to be due to rotational modulation. The luminosity and period we measured are comparable to those of other ultracool dwarfs observed at radio wavelengths. This implies that future megahertz to gigahertz surveys, with increased cadence and improved sensitivity, are likely to detect similar or later-type dwarfs. Our detection of WISE J062309.94−045624.6 makes this dwarf the coolest and latest-type star observed to produce radio emission.
Integrase Strand Transfer Inhibitor Use and Cancer Incidence in a Large Cohort Setting
Publisher: Oxford University Press (OUP)
Date: 19-01-2022
DOI: 10.1093/OFID/OFAC029
Abstract: Limited data exist examining the association between incident cancer and cumulative integrase inhibitor (INSTI) exposure. Participants were followed from baseline (latest of local cohort enrollment or January 1, 2012) until the earliest of first cancer, final follow-up, or December 31, 2019. Negative binomial regression was used to assess associations between cancer incidence and time-updated cumulative INSTI exposure, lagged by 6 months. Of 29 340 in iduals, 74% were male, 24% were antiretroviral treatment (ART)-naive, and median baseline age was 44 years (interquartile range [IQR], 36–51). Overall, 13 950 (48%) in iduals started an INSTI during follow-up. During 160 657 person-years of follow-up ([PYFU] median 6.2 IQR, 3.9–7.5), there were 1078 cancers (incidence rate [IR] 6.7/1000 PYFU 95% confidence interval [CI], 6.3–7.1). The commonest cancers were non-Hodgkin lymphoma (n = 113), lung cancer (112), Kaposi’s sarcoma (106), and anal cancer (103). After adjusting for potential confounders, there was no association between cancer risk and INSTI exposure (≤6 months vs no exposure IR ratio: 1.15 [95% CI, 0.89–1.49], & –12 months 0.97 [95% CI, 0.71–1.32], & –24 months 0.84 [95% CI, 0.64–1.11], & –36 months 1.10 [95% CI, 0.82–1.47], & months 0.90 [95% CI, 0.65–1.26] [P = .60]). In ART-naive participants, cancer incidence decreased with increasing INSTI exposure, mainly driven by a decreasing incidence of acquired immune deficiency syndrome cancers however, there was no association between INSTI exposure and cancer for those ART-experienced (interaction P & .0001). Cancer incidence in each INSTI exposure group was similar, despite relatively wide CIs, providing reassuring early findings that increasing INSTI exposure is unlikely to be associated with an increased cancer risk, although longer follow-up is needed to confirm this finding.
Kaposi Sarcoma Risk in HIV-Infected Children and Adolescents on Combination Antiretroviral Therapy From Sub-Saharan Africa, Europe, and Asia
Publisher: Oxford University Press (OUP)
Date: 30-08-2016
DOI: 10.1093/CID/CIW519
A sample of fast radio bursts discovered and localized with MeerTRAP at the MeerKAT telescope
Publisher: Oxford University Press (OUP)
Date: 08-07-2023
Abstract: We present a s le of well-localized fast radio bursts (FRBs) discovered by the MeerTRAP project at the MeerKAT telescope in South Africa. We discovered the three FRBs in single coherent tied-array beams and localized them to an area of ∼1 arcmin2. We investigate their burst properties, scattering, repetition rates, and localizations in a multiwavelength context. FRB 20201211A shows hints of scatter broadening but is otherwise consistent with instrumental dispersion smearing. For FRB 20210202D, we discovered a faint post-cursor burst separated by ∼200 ms, suggesting a distinct burst component or a repeat pulse. We attempt to associate the FRBs with host galaxy candidates. For FRB 20210408H, we tentatively (0.35–0.53 probability) identify a compatible host at a redshift ∼0.5. Additionally, we analyse the MeerTRAP survey properties, such as the survey coverage, fluence completeness, and their implications for the FRB population. Based on the entire s le of 11 MeerTRAP FRBs discovered by the end of 2021, we estimate the FRB all-sky rates and their scaling with the fluence threshold. The inferred FRB all-sky rates at 1.28 GHz are $8.2_{-4.6}^{+8.0}$ and $2.1_{-1.1}^{+1.8} \\times 10^3 \\: \\text{sky}^{-1} \\: \\text{d}^{-1}$ above 0.66 and 3.44 Jy ms for the coherent and incoherent surveys, respectively. The scaling between the MeerTRAP rates is flatter than at higher fluences at the 1.4σ level. There seems to be a deficit of low-fluence FRBs, suggesting a break or turn-over in the rate versus fluence relation below 2 Jy ms. We speculate on cosmological or progenitor-intrinsic origins. The cumulative source counts within our surveys appear consistent with the Euclidean scaling.
Detection of radio emission from stars via proper-motion searches
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/PASA.2023.26
Abstract: We present a method for identifying radio stellar sources using their proper-motion. We demonstrate this method using the FIRST, VLASS, RACS-low and RACS-mid radio surveys, and astrometric information from Gaia Data Release 3. We find eight stellar radio sources using this method, two of which have not previously been identified in the literature as radio stars. We determine that this method probes distances of $\\sim$ 90pc when we use FIRST and RACS-mid, and $\\sim$ 250pc when we use FIRST and VLASS. We investigate the time baselines required by current and future radio sky surveys to detect the eight sources we found, with the SKA (6.7 GHz) requiring $ $ 3 yr between observations to find all eight sources. We also identify nine previously known and 43 candidate variable radio stellar sources that are detected in FIRST (1.4 GHz) but are not detected in RACS-mid (1.37 GHz). This shows that many stellar radio sources are variable, and that surveys with multiple epochs can detect a more complete s le of stellar radio sources.
Incidence of hypertension in people with HIV who are treated with integrase inhibitors versus other antiretroviral regimens in the RESPOND cohort consortium
Publisher: Wiley
Date: 03-2022
DOI: 10.1111/HIV.13273
Abstract: To compare the incidence of hypertension in people living with HIV receiving integrase strand transfer inhibitor (INSTI)‐based antiretroviral therapy (ART) versus non‐nucleoside reverse transcriptase inhibitors (NNRTIs) or boosted protease inhibitors (PIs) in the RESPOND consortium of HIV cohorts. Eligible people with HIV were aged ≥18 years who initiated a new three‐drug ART regimen for the first time (baseline), did not have hypertension, and had at least two follow‐up blood pressure (BP) measurements. Hypertension was defined as two consecutive systolic BP measurements ≥140 mmHg and/or diastolic BP ≥90 mmHg or initiation of antihypertensives. Multivariable Poisson regression was used to determine adjusted incidence rate ratios (aIRRs) of hypertension, overall and in those who were ART naïve or experienced at baseline. Overall, 4606 people living with HIV were eligible (INSTIs 3164, NNRTIs 807, PIs 635). The median baseline systolic BP, diastolic BP, and age were 120 (interquartile range [IQR] 113–130) mmHg, 78 (70–82) mmHg, and 43 (34–50) years, respectively. Over 8380.4 person‐years (median follow‐up 1.5 [IQR 1.0–2.7] years), 1058 (23.0%) participants developed hypertension (incidence rate 126.2/1000 person‐years, 95% confidence interval [CI] 118.9–134.1). Participants receiving INSTIs had a higher incidence of hypertension than those receiving NNRTIs (aIRR 1.76 95% CI 1.47–2.11), whereas the incidence was no different in those receiving PIs (aIRR 1.07 95% CI 0.89–1.29). The results were similar when the analysis was stratified by ART status at baseline. Although unmeasured confounding and channelling bias cannot be excluded, INSTIs were associated with a higher incidence of hypertension than were NNRTIs, but rates were similar to those of PIs overall, in ART‐naïve and ART‐experienced participants within RESPOND.
Sofosbuvir/velpatasvir for 12 vs. 6 weeks for the treatment of recently acquired hepatitis C infection
Publisher: Elsevier BV
Date: 10-2021
DOI: 10.1016/J.JHEP.2021.04.056
Abstract: Shortened duration therapy for acute and recent HCV infection has been shown to be highly effective in several small non-randomised studies with direct-acting antiviral regimens however, large randomised studies are lacking. REACT was an NIH-funded multicentre international, open-label, randomised, phase IV non-inferiority trial examining the efficacy of short course (6-week) vs. standard course (12-week) therapy with sofosbuvir-velpatasvir for recent HCV infection (estimated duration of infection ≤12 months). Randomisation occurred at week 6. The primary endpoint was sustained virological response 12 weeks after treatment end (SVR12) in the intention-to treat (ITT) population. A total of 250 participants were due to be enrolled, but on advice of the data safety and monitoring board the study was halted early. The primary analysis population consisted of 188 randomised participants at termination of study enrolment short arm (n = 93), standard arm (n = 95). Ninety-seven percent were male and 69% HIV positive. ITT SVR12 was 76/93, 81.7% (95% CI 72.4-89.0) in the short arm and 86/95, 90.5% (95% CI 82.7-95.6) in the standard arm. The difference between the arms was -8.8 (95% CI -18.6 to 1.0). In modified ITT analysis, wherein non-virological reasons for failure were excluded (death, reinfection, loss to follow-up), SVR12 was 76/85, 89.4% (95% CI 80.8-95.0) in the short arm and 86/88, 97.7% in the standard arm (95% CI 92.0-99.7 difference -8.3%, p = 0.025). In this randomised study in recent HCV infection, a 6-week course of sofosbuvir-velpatasvir did not meet the criteria for non-inferiority to standard 12-week therapy. In this randomised trial, 188 people with recently acquired hepatitis C infection were randomly assigned to treatment using either a short 6-week course (93 people) or standard 12-week course (95 people) of the hepatitis C treatment sofosbuvir/velpatasvir. There were 9 cases of relapse after treatment with the short course and 2 following the standard course. A shortened course of 6-week therapy for hepatitis C infection appeared to be less effective than a standard 12-week course in people with recently acquired hepatitis C infection. CLINICALTRIALS. NCT02625909.
Global temporal changes in the proportion of children with advanced disease at the start of combination antiretroviral therapy in an era of changing criteria for treatment initiation
Publisher: Wiley
Date: 11-2018
DOI: 10.1002/JIA2.25200
Autoantibodies against type I IFNs in patients with life-threatening COVID-19
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-10-2020
Abstract: The immune system is complex and involves many genes, including those that encode cytokines known as interferons (IFNs). In iduals that lack specific IFNs can be more susceptible to infectious diseases. Furthermore, the autoantibody system d ens IFN response to prevent damage from pathogen-induced inflammation. Two studies now examine the likelihood that genetics affects the risk of severe coronavirus disease 2019 (COVID-19) through components of this system (see the Perspective by Beck and Aksentijevich). Q. Zhang et al. used a candidate gene approach and identified patients with severe COVID-19 who have mutations in genes involved in the regulation of type I and III IFN immunity. They found enrichment of these genes in patients and conclude that genetics may determine the clinical course of the infection. Bastard et al. identified in iduals with high titers of neutralizing autoantibodies against type I IFN-α2 and IFN-ω in about 10% of patients with severe COVID-19 pneumonia. These autoantibodies were not found either in infected people who were asymptomatic or had milder phenotype or in healthy in iduals. Together, these studies identify a means by which in iduals at highest risk of life-threatening COVID-19 can be identified. Science , this issue p. eabd4570 , p. eabd4585 see also p. 404
Low-frequency pulse profile variation in PSR B2217+47: evidence for echoes from the interstellar medium
Publisher: Oxford University Press (OUP)
Date: 13-02-2018
DOI: 10.1093/MNRAS/STY368
Mapping the human genetic architecture of COVID-19
Publisher: Springer Science and Business Media LLC
Date: 08-07-2021
DOI: 10.1038/S41586-021-03767-X
Abstract: The genetic make-up of an in idual contributes to the susceptibility and response to viral infection. Although environmental, clinical and social factors have a role in the chance of exposure to SARS-CoV-2 and the severity of COVID-19 1,2 , host genetics may also be important. Identifying host-specific genetic factors may reveal biological mechanisms of therapeutic relevance and clarify causal relationships of modifiable environmental risk factors for SARS-CoV-2 infection and outcomes. We formed a global network of researchers to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity. Here we describe the results of three genome-wide association meta-analyses that consist of up to 49,562 patients with COVID-19 from 46 studies across 19 countries. We report 13 genome-wide significant loci that are associated with SARS-CoV-2 infection or severe manifestations of COVID-19. Several of these loci correspond to previously documented associations to lung or autoimmune and inflammatory diseases 3–7 . They also represent potentially actionable mechanisms in response to infection. Mendelian randomization analyses support a causal role for smoking and body-mass index for severe COVID-19 although not for type II diabetes. The identification of novel host genetic factors associated with COVID-19 was made possible by the community of human genetics researchers coming together to prioritize the sharing of data, results, resources and analytical frameworks. This working model of international collaboration underscores what is possible for future genetic discoveries in emerging pandemics, or indeed for any complex human disease.
The Coding Causes of Death in HIV (CoDe) Project
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2011
Related Organisations
University Of Manchester
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
No related grants have been discovered for Marc van der Valk.