Refresh my memory: Episodic memory reinstatements intrude on working memory maintenance

A fundamental question in memory research is how different forms of memory interact. Previous research has shown that people rely on working memory (WM) in short-term recognition tasks; a common view is that episodic memory (EM) only influences performance on these tasks when WM maintenance is disrupted. However, retrieval of memories from EM has been widely observed during brief periods of quiescence, raising the possibility that EM retrievals during maintenance-critically, before a response can be prepared-might affect short-term recognition memory performance even in the absence of distraction. We hypothesized that this influence would be mediated by the lingering presence of reactivated EM content in WM. We obtained support for this hypothesis in three experiments, showing that delay-period EM reactivation introduces incidentally-associated information ( context ) into WM, and that these retrieved associations negatively impact subsequent recognition, leading to substitution errors (Experiment 1) and slowing of accurate responses (Experiment 2). fMRI pattern analysis showed that slowing is mediated by the content of EM reinstatement (Experiment 3). These results expose a previously hidden influence of EM on WM, raising new questions about the adaptive nature of their interaction

The Decline and Recovery of Thermal Oxidative Stability of Ultra-Low Sulfur Diesel Blends

Dissertation supervised by Professor Bruce D. Beaver The oxidative stability of ultra-low sulfur diesel (ULSD) has generally been expected to continuously decline over time. However, recent studies have suggested that it may fluctuate.1-2 In this study, the oxidative stability of stored commercially purchased ULSD was monitored with a methanol extraction method.3 In this methodology, proposed by Hardy and Wechter, fuel blends are extracted with methanol before and after thermal stressing.4 The methanol-soluble layer contains the oxygenated and oxidizable components of the fuel (SMORS) and the change in this mass upon stressing thus represents the oxidative stability of the fuel. Over the course of 145 days of storage under various conditions; this mass difference – called the SMORS mass was observed to recover, decline and recover again. In a concurrently run study – phenol was generated within two simplified ULSD blends consisting of 25% cumene in heptane after 38 days of lab storage. The amount of phenol peaked between days 62 and 76. Within the same time frame, the oxidative stability of the similarly stored ULSD peaked. This suggests that phenol was also generated within the ULSD and that this in situ generated phenol served to increase the oxidative stability. Infrared spectra of deposits formed during stress runs suggests the formation of quinones. This in turn suggests that the subsequent loss of oxidative stability is due to the conversion of the generated phenols to quinones – which would then undergo coupling reactions, eventually yielding high molecular weight deposits.

Amphetamine induced activation of the opioid system: a focused review of animal and human studies

Stimulants are commonly prescribed as first line medications for ADHD and also used as adjunct treatment in other psychiatric conditions. While much is known about stimulants’ influence on brain neurochemistry, particularly on the dopaminergic neurotransmission, there has been less research into prescription stimulants’ effects on the endogenous opioid system. What we know about the mechanisms underlying the effects of stimulants on the opioid system come predominantly from animal studies and a relatively small number of studies in humans using positron emission tomography (PET) to examine the activation of the endogenous opioid system as evidenced by radioligand binding to opioid receptors. This paper is a focused review of the currently available literature on both animal and human studies examining the effects of stimulant administration on the endogenous opioid system, which suggest that stimulant administration results in increased occupancy of the opioid receptors in a widespread network of brain regions. We discuss the possible underlying mechanisms of this interaction, it’s potential impact on our understanding of substance abuse and addiction, particularly as viewed through the model of behavioral sensitization, and possible clinical implications

Healing Through History: a qualitative evaluation of a social medicine consultation curriculum for internal medicine residents

Background: Social context guides care; stories sustain meaning; neither is routinely prioritized in residency training. Healing Through History (HTH) is a social medicine consultation curriculum integrating social determinants of health narrative into clinical care for medically and socially complex patients. The curriculum is part of an internal medicine (IM) residency outpatient clinical rotation at a Veterans Health Administration hospital. Our aim was to explore how in-depth social medicine consultations may impact resident clinical practice and foster meaning in work. Methods: From 2017 to 2019, 49 categorical and preliminary residents in their first year of IM training were given two half-day sessions to identify and interview a patient; develop a co-produced social medicine narrative; review it with patient and faculty; and share it in the electronic health record (EHR). Medical anthropologists conducted separate 90-min focus groups of first- and second-year IM residents in 2019, 1–15 months from the experience. Results: 46 (94%) completed HTH consultations, of which 40 (87%) were approved by patients and published in the EHR. 12 (46%) categorical IM residents participated in focus groups; 6 PGY1, and 6 PGY2. Qualitative analysis yielded 3 themes: patient connection, insight, and clinical impact; clinical skill development; and structural barriers to the practice of social medicine. Conclusions: HTH offers a model for teaching co-production through social and narrative medicine consultation in complex clinical care, while fostering meaning in work. Integration throughout training may further enhance impact

Acetylene Fuels TCE Reductive Dechlorination by Defined Dehalococcoides/Pelobacter Consortia.

Acetylene (C2H2) can be generated in contaminated groundwater sites as a consequence of chemical degradation of trichloroethene (TCE) by in situ minerals, and C2H2 is known to inhibit bacterial dechlorination. In this study, we show that while high C2H2 (1.3 mM) concentrations reversibly inhibit reductive dechlorination of TCE by Dehalococcoides mccartyi isolates as well as enrichment cultures containing D. mccartyi sp., low C2H2 (0.4 mM) concentrations do not inhibit growth or metabolism of D. mccartyi. Cocultures of Pelobacter SFB93, a C2H2-fermenting bacterium, with D. mccartyi strain 195 or with D. mccartyi strain BAV1 were actively sustained by providing acetylene as the electron donor and carbon source while TCE or cis-DCE served as the electron acceptor. Inhibition by acetylene of reductive dechlorination and methanogenesis in the enrichment culture ANAS was observed, and the inhibition was removed by adding Pelobacter SFB93 into the consortium. Transcriptomic analysis of D. mccartyi strain 195 showed genes encoding for reductive dehalogenases (e.g., tceA) were not affected during the C2H2-inhibition, while genes encoding for ATP synthase, biosynthesis, and Hym hydrogenase were down-regulated during C2H2 inhibition, consistent with the physiological observation of lower cell yields and reduced dechlorination rates in strain 195. These results will help facilitate the optimization of TCE-bioremediation at contaminated sites containing both TCE and C2H2

Are Survey-Based Estimates of the Burden of Drug Resistant TB Too Low? Insight from a Simulation Study

Background: The emergence of tuberculosis resistant to multiple first- and second-line antibiotics poses challenges to a global control strategy that relies on standard drug treatment regimens. Highly drug-resistant strains of Mycobacterium tuberculosis have been implicated in outbreaks and have been found throughout the world; a comprehensive understanding the magnitude of this threat requires an accurate assessment of the worldwide burden of resistance. Unfortunately, in many settings where resistance is emerging, laboratory capacity is limited and estimates of the burden of resistance are obtained by performing drug sensitivity testing on a sample of incident cases rather than through the use of routine surveillance. Methodology/Principal Findings: Using an individual-based dynamic tuberculosis model to simulate surveillance strategies for drug resistance, we found that current surveys may underestimate the total burden of resistant tuberculosis because cases of acquired resistance are undercounted and resistance among prevalent cases is not assessed. We explored how this bias is affected by the maturity of the epidemic and by the introduction of interventions that target the emergence and spread of resistant tuberculosis. Conclusions: Estimates of drug resistant tuberculosis based on samples of incident cases should be viewed as a lower bound of the total burden of resistance

Toll-like receptor gene variants and bacterial vaginosis among HIV-1 infected and uninfected African women.

Bacterial vaginosis (BV) is a common vaginal syndrome associated with altered microflora that increases the risk of preterm delivery and acquisition of sexually transmitted diseases. The cause of BV is unknown although toll-like receptors (TLRs), that are central to innate immune responses, may be important. We evaluated associations between TLR SNPs and BV among HIV-1 infected and uninfected African women. Logistic regression was used to assess associations between SNPs (N=99) in TLRs 2-4, 7-9 and BV (as classified by Nugent's criteria). Among HIV-1 uninfected women, TLR7 rs5743737 and TLR7 rs1634323 were associated with a decreased risk of BV, whereas TLR7 rs179012 was associated with an increased risk. TLR2 SNP rs3804099 was associated with a decreased risk of BV among HIV-1 infected women. Our findings indicate that there may be differences in TLR association with BV among HIV-1 infected and HIV-1 uninfected women

The Role of HIV-Related Stigma in Utilization of Skilled Childbirth Services in Rural Kenya:A Prospective Mixed-Methods Study

BACKGROUND: Childbirth with a skilled attendant is crucial for preventing maternal mortality and is an important opportunity for prevention of mother-to-child transmission of HIV. The Maternity in Migori and AIDS Stigma Study (MAMAS Study) is a prospective mixed-methods investigation conducted in a high HIV prevalence area in rural Kenya, in which we examined the role of women's perceptions of HIV-related stigma during pregnancy in their subsequent utilization of maternity services. METHODS AND FINDINGS: From 2007–2009, 1,777 pregnant women with unknown HIV status completed an interviewer-administered questionnaire assessing their perceptions of HIV-related stigma before being offered HIV testing during their first antenatal care visit. After the visit, a sub-sample of women was selected for follow-up (all women who tested HIV-positive or were not tested for HIV, and a random sample of HIV-negative women, n = 598); 411 (69%) were located and completed another questionnaire postpartum. Additional qualitative in-depth interviews with community health workers, childbearing women, and family members (n = 48) aided our interpretation of the quantitative findings and highlighted ways in which HIV-related stigma may influence birth decisions. Qualitative data revealed that health facility birth is commonly viewed as most appropriate for women with pregnancy complications, such as HIV. Thus, women delivering at health facilities face the risk of being labeled as HIV-positive in the community. Our quantitative data revealed that women with higher perceptions of HIV-related stigma (specifically those who held negative attitudes about persons living with HIV) at baseline were subsequently less likely to deliver in a health facility with a skilled attendant, even after adjusting for other known predictors of health facility delivery (adjusted odds ratio = 0.44, 95% CI 0.22–0.88). CONCLUSIONS: Our findings point to the urgent need for interventions to reduce HIV-related stigma, not only for improving quality of life among persons living with HIV, but also for better health outcomes among all childbearing women and their families. Please see later in the article for the Editors' Summary

Reducing the Carbon Footprint of Academic Conferences:The Example of the American Society of Tropical Medicine and Hygiene

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