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Photosynthesis is generally assumed to be initiated by a single photon1-3 from the Sun, which, as a weak light source, delivers at most a few tens of photons per nanometre squared per second within a chlorophyll absorption band1. Yet much experimental and theoretical work over the past 40 years has explored the events during photosynthesis subsequent to absorption of light from intense, ultrashort laser pulses2-15. Here, we use single photons to excite under ambient conditions the light-harvesting 2 (LH2) complex of the purple bacterium Rhodobacter sphaeroides, comprising B800 and B850 rings that contain 9 and 18 bacteriochlorophyll molecules, respectively. Excitation of the B800 ring leads to electronic energy transfer to the B850 ring in approximately 0.7 ps, followed by rapid B850-to-B850 energy transfer on an approximately 100-fs timescale and light emission at 850-875 nm (refs. 16-19). Using a heralded single-photon source20,21 along with coincidence counting, we establish time correlation functions for B800 excitation and B850 fluorescence emission and demonstrate that both events involve single photons. We also find that the probability distribution of the number of heralds per detected fluorescence photon supports the view that a single photon can upon absorption drive the subsequent energy transfer and fluorescence emission and hence, by extension, the primary charge separation of photosynthesis. An analytical stochastic model and a Monte Carlo numerical model capture the data, further confirming that absorption of single photons is correlated with emission of single photons in a natural light-harvesting complex.

IntroductionUnhealthy alcohol use is associated with a range of adverse outcomes among people with HIV (PWH). Testing the efficacy and promoting the availability of effective interventions to address unhealthy alcohol use among PWH is thus a priority. Alcohol use outcomes in intervention studies are often measured by self-report alone, which can lead to spurious results due to information biases (eg, social desirability). Measuring alcohol outcomes objectively through biomarkers, such as phosphatidylethanol (PEth), in addition to self-report has potential to improve the validity of intervention studies. This protocol outlines the methods for a systematic review and individual participant data meta-analysis that will estimate the efficacy of interventions to reduce alcohol use as measured by a combined categorical self-report/PEth variable among PWH and compare these estimates to those generated when alcohol is measured by self-report or PEth alone.Methods and analysisWe will include randomised controlled trials that: (A) tested an alcohol intervention (behavioural and/or pharmacological), (B) enrolled participants 15 years or older with HIV; (C) included both PEth and self-report measurements, (D) completed data collection by 31 August 2023. We will contact principal investigators of eligible studies to inquire about their willingness to contribute data. The primary outcome variable will be a combined self-report/PEth alcohol categorical variable. Secondary outcomes will include PEth alone, self-report alone and HIV viral suppression. We will use a two-step meta-analysis and random effects modelling to estimate pooled treatment effects; I2 will be calculated to evaluate heterogeneity. Secondary and sensitivity analyses will explore treatment effects in adjusted models and within subgroups. Funnel plots will be used to explore publication bias.Ethics and disseminationThe study will be conducted with deidentified data from completed randomised controlled trials and will be considered exempt from additional ethical approval. Results will be disseminated through peer-reviewed publications and international scientific meetings.Prospero registration numberCRD42022373640.

This study evaluated the association between impulsivity and linkage to HIV care among Russians living with HIV recruited from an inpatient narcology hospital. Linking Infectious and Narcology Care (LINC) study participants who completed the Barratt Impulsiveness Scale (BIS) were included in these analyses. The primary independent variable was impulsivity score which was categorized as high impulsivity (BIS score > 71) vs. low impulsivity (BIS score

The Consortium for Medical Marijuana Clinical Outcomes Research, a multi-university collaboration established by the state of Florida in the USA, hosted its third annual Cannabis Clinical Outcomes Research Conference (CCORC) in May 2023. CCORC was held as a hybrid conference, with a scientific program consisting of in-person sessions, with some sessions livestreamed to virtual attendees. CCORC facilitated and promoted up-to-date research on the clinical effects of medical cannabis, fostering collaboration and active involvement among scientists, policymakers, industry professionals, clinicians, and other stakeholders. Three themes emerged from conference sessions and speaker presentations: (1) disentangling conflicting evidence for the effects of medical cannabis on public health, (2) seeking solutions to address barriers faced when conducting clinical cannabis research - especially with medical cannabis use in special populations such as those who are pregnant, and (3) unpacking the data behind cannabis use and mental health outcomes. The fourth annual CCORC is planned for the summer of 2024 in Florida, USA. Keywords: Mental health, Public health, Cannabis Clinical Outcomes Research Conference, Conference proceedings, Medical marijuana, Cannabis, Cannabinoids, Cannabidiol, Marijuana efficacy, Marijuana clinical outcomes, Author(s): Amie J. Goodin [a,b,c]; Phuong T. Tran [a]; Sam McKee [a,c]; Ruba Sajdeya [c,d]; Jeevan Jyot [a,c]; Robert L. Cook [c,d,e]; Yan Wang [c,d]; Almut G. Winterstein [a,b,c] Introduction [...]

BackgroundObjective measurement of alcohol consumption is important for clinical care and research. Adjusting for self-reported alcohol use, we conducted an individual participant data (IPD) meta-analysis to examine factors associated with the sensitivity of phosphatidylethanol (PEth), an alcohol metabolite, among persons self-reporting unhealthy alcohol consumption.MethodsWe identified 21 eligible studies and obtained 4073 observations from 3085 participants with Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) positive scores (≥3 for women and ≥4 for men) and PEth measurements. We conducted 1-step IPD meta-analysis using mixed effects models with random intercepts for study site. We examined the associations between demographic (sex, race/ethnicity, and age) and biologic (body mass index-BMI, hemoglobin, HIV status, liver fibrosis, and venous versus finger-prick blood collection) variables with PEth sensitivity (PEth≥8 ng/ml), adjusting for the level of self-reported alcohol use using the AUDIT-C score.ResultsOne third (31%) of participants were women, 32% were African, 28% African American, 28% White, and 12% other race/ethnicity. PEth sensitivity (i.e., ≥8 ng/ml) was 81.8%. After adjusting for AUDIT-C, we found no associations of sex, age, race/ethnicity, or method of blood collection with PEth sensitivity. In models that additionally included biologic variables, those with higher hemoglobin and indeterminate and advanced liver fibrosis had significantly higher odds of PEth sensitivity; those with higher BMI and those living with HIV had significantly lower odds of PEth sensitivity. African Americans and Africans had higher odds of PEth sensitivity than whites in models that included biologic variables.ConclusionsAmong people reporting unhealthy alcohol use, several biological factors (hemoglobin, BMI, liver fibrosis, and HIV status) were associated with PEth sensitivity. Race/ethnicity was associated with PEth sensitivity in some models but age, sex, and method of blood collection were not. Clinicians should be aware of these factors, and researchers should consider adjusting analyses for these characteristics where possible.

BackgroundDirect biomarkers such as phosphatidylethanol (PEth) have the capability to detect heavy alcohol use, but it is unclear how strongly self-reported reduction in alcohol use correlates with reduction in PEth. We sought to explore the strength of correlation between reductions in self-reported alcohol use and change in PEth among a sample of women living with HIV (WLWH) who participated in a clinical trial to reduce heavy alcohol use. We also sought to determine whether this correlation was stronger in women with lower body mass index (BMI) and women without an alcohol use disorder (AUD).Methods81 WLWH (mean age = 48.7, 80% Black) engaging in a randomized trial of naltrexone versus placebo with a positive baseline PEth (≥8 ng/ml), and alcohol use data at baseline, 2, and 7 months were included in this analysis. Spearman correlation coefficients were compared to measure the correlation between baseline PEth and number of drinks per week by demographic, biological, and alcohol use factors. Mini-International Neuropsychiatric Interview was used to screen for AUD. Further analyses were stratified by BMI and AUD. Spearman correlation coefficients were calculated for the change in PEth and the change in number of drinks per week over 7 months, including 3 time-points: baseline, 2, and 7 months.ResultsAt baseline, the correlation between baseline PEth and the number of drinks per week was significantly stronger for those with a BMI ≤25 compared to those with a BMI > 25 (r = 0.66; r = 0.26, respectively). Similarly, the correlation between baseline PEth and number of drinks was stronger for those who did not screen positive for AUD compared with those who did (r = 0.66; r = 0.25, respectively). When stratifying by BMI, a low-to-moderate correlation (r = 0.32, p = 0.02) was present for persons with a BMI > 25; when stratifying by AUD, a moderate correlation (r = 0.50, p

We use quantum trajectory theory to study the dynamics of the first step in photosynthesis for a single photon interacting with photosystem II (PSII). By considering individual trajectories we are able to look beyond the ensemble average dynamics to compute the PSII system evolution conditioned upon individual photon counting measurements. Measurements of the transmitted photon beam strongly affects the system state, since detection of an outgoing photon confirms that the PSII must be in the electronic ground state, while a null measurement implies it is in an excited electronic state. We show that under ideal conditions, observing the null result transforms a state with a low excited state population to a state with nearly all population contained in the excited states. We study the PSII dynamics conditioned on such photon counting for both a pure excitonic model of PSII and a more realistic model with exciton-phonon coupling to a dissipative phononic environment. In the absence of such coupling, we show that the measured fluorescence rates show oscillations constituting a photon-counting witness of excitonic coherence. Excitonic coupling to the phonon environment has a strong effect on the observed rates of fluorescence, damping the oscillations. Addition of non-radiative decay and incoherent transitions to radical pair states in the reaction center to the phononic model allows extraction of a quantum efficiency of 92.5% from the long-time evolution, consistent with bulk experimental measurements. [ABSTRACT FROM AUTHOR]

BackgroundThe relationship between alcohol consumption and atherosclerosis has not been sufficiently examined among people living with HIV (PLWH).MethodsWe analyzed data from PLWH in the Women's Interagency HIV Study (WIHS; n = 1,164) and the Multicenter AIDS Cohort Study (MACS; n = 387) with no history of cardiovascular disease (CVD). Repeated measures of intima-media thickness of the right common carotid artery (CCA-IMT) were assessed using B-mode ultrasound from 2004 to 2013. Current alcohol consumption was collected at time of CCA-IMT measurement and was categorized according to gender-specific weekly limits. Group-based trajectory models categorized participants into past 10-year consumption patterns (1994 to 2004). Multivariate generalized estimating equations were conducted to assess the association of past and current alcohol use patterns on change in CCA-IMT by cohort, controlling for age, race, cigarette and illicit drug use, probable depression, HIV RNA viral load, antiretroviral therapy exposure, and hepatitis C coinfection.ResultsAmong the WIHS, past heavy alcohol consumption was associated with increased CCA-IMT level over time (β = 8.08, CI 0.35, 15.8, p = 0.04), compared to abstinence. Among the MACS, compared to abstinence, all past consumption patterns were associated with increased CCA-IMT over time (past low: β = 15.3, 95% CI 6.46, 24.2, p

BackgroundThe long-term effects of marijuana on cognition, particularly in the context of HIV is not clear, as extant research shows mixed findings.ObjectiveTo determine associations between current and cumulative exposure to marijuana and changes in cognitive processing speed and flexibility in 788 HIV-seropositive (HIV+) and 1,132 HIV-seronegative (HIV-) men followed for up to 17 years in the Multicenter AIDS Cohort Study.ResultsAmong HIV+ men only, current daily marijuana use compared to none-use, was significantly associated with a greater annual percentage decline in cognitive processing speed assessed with the Trail Making Test A (TMTA) (β=-0.41, 95% confidence interval (CI): -0.88, -0.03, p=0.03)] and Symbol Digit Modalities Test (SDMT) (β= -0.14, 95% CI: -0.28, -0.01, p=0.04). Further, monthly marijuana use was associated with greater annual percentage decline in cognitive flexibility assessed with the Trail Making Test B (TMTB) (β= -0.70, 95% CI: -1.34, -0.05; p=0.03] and cognitive processing speed (SDMT) (β= -0.21, 95% CI: -0.40, -0.01, p=0.03). Among the HIV- men only, each 5-marijuana use-years (equivalent to 5-years of daily marijuana use) was significantly associated with a 0.17 annual percentage decline in cognitive processing speed only (TMTA) (β= -0.18, 95% CI: -0.36, -0.01; p=0.04).ConclusionsOur findings suggest that marijuana use, particularly current use, may be associated with worse cognitive processing speed, but the magnitude of the estimates was not clinically meaningful.

The Cannabis Clinical Outcomes Research Conference (CCORC) 2021 was held virtually on April 8 and 9, 2021. The conference was hosted by the Consortium for Medical Marijuana Clinical Outcomes Research, a research organization instituted by the state legislature of Florida in the United States. The inaugural annual CCORC 2021 was organized as a scientific meeting to foster and disseminate research on medical marijuana (MM) clinical outcomes, while promoting engagement among MM researchers, patients, clinicians, policymakers, and industry partners. Key conference themes included: (a) the disconnect between policy, practice, and evidence and steps towards reconciliation, (b) approaches to overcome common barriers to MM research, and (c) the use of focused translational approaches utilizing both mechanistic and clinical research methodology to tackle the complexities of MM outcomes. CCORC 2022 is planned for spring 2022 in Orlando, Florida, United States. Keywords: Conference proceedings, Medical marijuana, Cannabis, Marijuana clinical outcomes, Author(s): Amie J. Goodin (corresponding author) [a,b,c]; Debbie L. Wilson [a]; Robert L. Cook [c,d,e]; Yan Wang [c,d]; Joshua Brown [a,b,c]; Almut G. Winterstein [a,b,c,d] Florida is one of 36 [...]

BackgroundBiomarkers can play a key role in supplementing self-report information in alcohol research. In this study, we examined phosphatidylethanol (PEth) in comparison with self-reported alcohol use over time in a randomized controlled trial.MethodsParticipants were women living with HIV enrolled in a randomized placebo-controlled trial of naltrexone for reducing hazardous drinking. Drinking behavior was measured using Timeline Followback (TLFB), and PEth as a biomarker using dried blood spots. Data collected at baseline, and months 2 and 7 were analyzed. In addition to calculated Spearman's correlations, mixed-effects modeling was used to evaluate the changes in self-reported drinking and PEth, respectively, adjusting for body mass index (BMI).ResultsA total of 194 participants (83% black, mean age 48) were included in the analysis. PEth levels were significantly correlated with self-reported drinking via TLFB, Spearman's r = 0.21 at baseline, r = 0.29 at 2 months, and r = 0.28 at 7 months, respectively. No demographic or health factors, except for BMI, was associated with whether self-report was consistent with PEth. Mixed-effects model indicated that self-reported drinking showed significantly greater reductions in the naltrexone treatment group than the placebo group at the 2- and 7-month visits, whereas PEth measure only showed this difference at the 7-month follow-up.ConclusionsThe magnitude of the correlation between PEth and self-reported alcohol consumption was small. Caution is needed when using either self-report or PEth as a sole outcome measure for alcohol behavior changes in clinical trials.

BackgroundMarijuana use is common among HIV+ individuals, but few studies have examined long-term trends in prevalence and correlates of use.MethodsWe evaluated trends (1984-2013) in the annual prevalence of current (past 6-month use) and daily (among current users) marijuana use and determined correlates of use among 2742 HIV-seropositive (HIV+) and 3172 HIV-seronegative (HIV-) men who have sex with men in the Multicenter AIDS Cohort Study (MACS). Poisson regression models were used to estimate prevalence ratios of marijuana use separately for the men who were enrolled before 2001 (early-cohort) and after 2001 (late-cohort).ResultsOver the 29 years of the study, the prevalence of current marijuana use declined significantly, whereas daily use among users increased among all men in the early and late-cohorts. A HIV+ status was associated with higher prevalence of marijuana use among the men in the early-cohort (adjusted prevalence ratio [aPR] = 1.53, 95% confidence interval [CI]:1.42, 1.64, p =