Increased dolutegravir peak concentrations in people living with HIV aged 60 and over and analysis of sleep quality and cognition

Background Demographic data show an increasingly aging HIV population worldwide. Recent concerns over dolutegravir-related neuropsychiatric toxicity have emerged, particularly amongst older HIV patients. We describe the pharmacokinetics (PK) of dolutegravir (DTG) 50mg once daily in people living with HIV (PLWH) aged 60 and older. Additionally, to address the call for prospective neuropsychiatric toxicodynamic data, we evaluate changes in sleep quality and cognitive function after switching to abacavir (ABC)/lamivudine (3TC)/DTG, over 6 months in this population. Methods PLWH aged≥60years with HIV-RNA<50copies/mL on any non-DTG based antiretroviral combination were switched to ABC/3TC/DTG. On day 28, 24-hour PK sampling was undertaken. Steady-state PK parameters were compared to a published historical control population aged≤50years. Six validated sleep questionnaires and neurocognitive (Cogstate®) testing were administered pre-switch and over 180 days (NCT02509195). Results Forty-three participants were enrolled; 40 completed the PK phase. Overall, five discontinued (two due adverse events, both sleep related, 4.6%). DTG maximum concentration (Cmax) was significantly higher in patients≥60 versus controls (GM 4246ng/mL versus 3402ng/mL, p=0.005). In those who completed day 180 (n=38), sleep impairment was higher at day 28 (PSQI median global score 5.0 versus 6.0 p=0.02) but not at day 90 or 180. Insomnia, daytime function, fatigue test scores did not change statistically over time. Conclusion DTG Cmax was significantly higher in older PLWH. Our data provides clinicians with key information on the safety of prescribing DTG in older PLWH

Investigation of Coherent Vibrational Signatures with Impulsive Transient Absorption Spectroscopy

In Chapter 1, we present the background for transient absorption spectroscopy through the polarization response of a material to an electric field which gives rise to linear and non-linear processes. We then discuss a theoretical description of how vibrational coherences are formed via four-wave mixing and impulsive excitation. We also describe signatures of coherent wavepackets in transient absorption and the application of vibrational coherences, specifically to observe non-radiative processes. We then summarize two previous studies using impulsive transient absorption on cresyl violet, the differences in the coherent dynamics reported, and the motivations behind the experiments presented in this work. Chapter 2 pertains to the apparatus used to perform the transient absorption experiments. We detail the source for the generation of ultrashort laser pulses (durations of less than 10 fs) used for the pump and probe from an argon-based white-light filament and non-colinear optical parametric amplifier. Two-dimensional shearing interferometry, the method used to measure the ultrashort pulses across a large portion of the visible spectrum (500-750 nm), is discussed. The retrieved temporal, spectral, and phase profiles of the pump and probe pulses are presented. Finally, the sample preparation for cresyl violet is described as well as the detection method and data processing used to generate the figures throughout this work. In Chapter 3, we present the results of impulsive transient absorption spectroscopy of cresyl violet perchlorate under four pump conditions. First, we report a study on controlling the formation of vibrational coherences on the ground or excited electronic states of cresyl violet by tuning the pump conditions from an off-resonant to a resonant scheme. The decay of the electronic population and positions of the stimulated emission and excited-state absorption maximums shows a dependence on the pump wavelength. Higher excitation frequencies blueshifts the stimulated emission 18 meV and red shifts excited-state absorption by 4 meV at early times compared to only 13 meV and 2 meV when using lower excitation frequencies. Coherent vibrations are observed and persist for approximately 6 ps after excitation, with phase flips appearing at 593 nm, the absorption maximum, after off-resonant excitation and at the emission (619 nm) and excited-state absorption (500 nm) maximums after resonant excitation. The ground- and excited-state vibrational modes are characterized by Fourier transform Raman spectroscopy. The excited-state vibration spectrum is shown to share nearly identical features as the ground-state, with each vibration slightly red-shifted, 2-10 cm-1, from the corresponding mode in the ground-state, particularly a prominent peak appearing at 594 cm-1 in the ground-state and 589 cm-1 in the excited-state. Next, two additional pump conditions using broadband and partially resonant pump pulses are explored to replicate the conflicting reports of non-adiabatic crossings in cresyl violet. Constant phase-flips observed in the control studies are replaced with phase flips that appear and disappear over several picoseconds. The Fourier Raman spectrum of the coherent signal after broadband excitation displays a mix of ground- and excited-state features, particularly prominent peaks at both 589 cm-1 and 594 cm-1. In Chapter 4, we analyze the coherent signals after broadband excitation using a Fourier filtering technique to isolate the ground- or excited-state coherent dynamics by carefully selecting representative vibrational modes for each state. Using a narrow filter to isolate the 589 cm-1 and 595 cm-1 features in the broadband Fourier Raman spectrum successfully isolates coherent vibrations with phase flips at either the emission and excited-state absorption maximums or the ground-state absorption maximum, respectively. A filter that includes both features generates apparent phase-flips that only appear for ~1ps and at probe wavelengths that do not correspond to the emission or absorption maximums. In Chapter 5, we present a simulation of the coherent signals using a model of two wavepackets with carrier frequencies of 589 cm-1 and 595 cm-1 and dephasing rates of 2 and 3 ps, respectively. Comparison to the broadband pump conditions and Fourier filtered coherent oscillations shows that the complex temporal dynamics observed are adequately described by the linear interference of two vibrational coherences evolving on different electronic potential energy surfaces, without the need to invoke non-adiabatic dynamics.Chemistr

Neither wasted nor wanted: theorising the failure to dispossess objects of ambiguous value

peer-reviewedConsumer research has traditionally presented the consumption process in three stages – acquisition, consumption and disposition (de Coverly et al. 2008; Jacoby, Berning, and Dietvorst 1977) and it is assumed that consumers will naturally move through the process (Cross, Leizerovici, and Pirouz 2017). Whereas commodity acquisition and utilisation have been researched extensively, disposition has received scant attention – a curiosity given its ubiquity and significance in consumer’s lives (Arnould and Thompson 2005). Disposition is a significant issue. Whether it is a painful process, during which individuals endure an experience akin to the death of some piece of themselves or the joyful shedding of objects imbued with an unwanted self, disposition is an integral part of modern life (Lastovicka and Fernandez 2005; Price et al. 2000). There are exceptions to this process, for example, hoarders, collectors and particularly frugal consumers retain commodities beyond their expected life cycle (Belk, Wallendorf, and Sherry 1989; Coulter and Ligas 2003; Haws et al. 2012; Lastovicka et al. 1999). Indeed, there are certain categories of goods which are retained indefinitely either due to their emotional or financial value (Belk et al. 1989; Jacoby et al. 1977). Epp and Price (2010) ask why some valued items are banished to storage while others remain in active use. Items which are no longer useful may also be kept, living indefinitely in nooks and crannies around the home. These items are particularly interesting for consumer researchers because their retention in consumer homes reveal that assumptions regarding disposition processes need to be re-examined. As such, this paper asks what happens to things when they are neither wasted nor wanted, when the little meaning they initially held was tied to another, more valuable object or when they have been replaced. This paper stems from a larger project exploring technological waste disposition. Analysis revealed a kind of object which is retained indefinitely, which does not hold special meaning, is not particularly valuable or personal. These objects are of ambiguous value to the owner (including obsolete cell phones, laptops, unused cables, lockless keys, long paid bills) – objects that seem to hover between being wanted and wasted - they hold the ghost of meaning or the possibility of (re)use.PUBLISHEDpeer-reviewe

Future e-waste scenarios

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