Publications by authors named "Ratcliff A"

Many central nervous system (CNS) disorders lack approved treatment options. Previous research demonstrated that peptide CAQK can bind to chondroitin sulfate proteoglycans (CSPGs) in the extracellular matrix of the CNS. In vivo studies have investigated CAQK conjugated to nanoparticles containing therapeutic agents with varying methodologies/outcomes.

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Patient perspectives are essential to understand healthcare disparities such as low rates of advance care planning (ACP) among adults with limited income. We completed twenty semi-structured interviews using purposive and snowball sampling. Initial and final themes emerged from inductive inclusion of recurring codes and deductive application of the cumulative disadvantage theory.

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Background: Veterans Affairs (VA) implemented the Veteran-centered Whole Health System initiative across VA sites with approaches to implementation varying by site.

Purpose: Using the Consolidated Framework for Implementation Research (CFIR), we aimed to synthesize systemic barriers and facilitators to Veteran use with the initiative. Relevance to healthcare quality, systematic comparison of implementation procedures across a national healthcare system provides a comprehensive portrait of strengths and opportunities for improvement.

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Background: Impaired vagal function in older individuals, quantified by the 'gold standard' delayed heart rate recovery after maximal exercise (HRR), is an independent predictor of cardiorespiratory capacity and mortality (particularly when HRR ≤12 beats min). Heart rate also often declines after orthostatic challenge (HRR), but the mechanism remains unclear. We tested whether HRR reflects similar vagal autonomic characteristics as HRR.

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Objectives: Low-income, older adults are less likely than those with high income to participate in advance care planning (ACP); however, the pandemic may have influenced their views. The aim of this report was to explore the perceptions of COVID-19 related to everyday life and ACP.

Methods: We embedded ACP behavior inequities within the Social Ecological Model to highlight the importance of considering social inequities within an environmental context.

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A rare but natural polymorphism in the HIV-1 envelope (Env) glycoprotein, lysine at position 425 was selected as a mutation conferring resistance to maraviroc (MVC) . N425K has not been identified in HIV-infected individuals failing an MVC-based treatment. This study reports that the rare K425 polymorphism in an HIV-1 subtype A Env has increased affinity for CD4, resulting in faster host cell entry kinetics and the ability to scavenge for low cell surface expression of CD4 to mediate entry.

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This preliminary qualitative study aimed to explore affordable housing specialists' perceptions of challenges and patterns of advance care planning behaviors among low-income older residents in affordable housing. Advance care planning rates among such residents are disproportionally lower than higher-income older adults. Individual telephone interviews were conducted with affordable housing specialists in a major urban area in the Southeastern United States (N = 5).

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Exposure of the genital mucosa to a genetically diverse viral swarm from the donor HIV-1 can result in breakthrough and systemic infection by a single transmitted/founder (TF) virus in the recipient. The highly diverse HIV-1 envelope (Env) in this inoculating viral swarm may have a critical role in transmission and subsequent immune response. Thus, chronic (Env) and acute (Env) Env chimeric HIV-1 were tested using multivirus competition assays in human mucosal penile and cervical tissues.

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Purpose: A parental history of substance abuse is a key risk factor for offspring's substance abuse. Identification of factors that may mitigate this effect is prerequisite to promoting resilience. In this study, we consider the substance use of peers in an adolescent's friendship network as a potential moderator of intergenerational continuity in substance abuse.

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Background: Like all viruses, HIV-1 relies on host systems to replicate. The human purinome consists of approximately two thousand proteins that bind and use purines such as ATP, NADH, and NADPH. By virtue of their purine binding pockets, purinome proteins are highly druggable, and many existing drugs target purine-using enzymes.

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Many tumors are dependent on de novo fatty acid synthesis to maintain cell growth. Fatty acid synthase (FASN) catalyzes the final synthetic step of this pathway, and its upregulation is correlated with tumor aggressiveness. The consequences and adaptive responses of acute or chronic inhibition of essential enzymes such as FASN are not fully understood.

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Despite only 30,000 group O HIV-1 infections, a similar genetic diversity is observed among the O subgroups H (head) and T (tail) (previously described as subtypes A, B) as in the 9 group M subtypes (A-K). Group O isolates bearing a cysteine at reverse transcriptase (RT) position 181, predominantly the H strains are intrinsically resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs). However, their susceptibility to newer antiretroviral drugs such as etravirine, maraviroc, raltegravir (RAL), and elvitegravir (EVG) remains relatively unknown.

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Small-molecule CCR5 antagonists, such as maraviroc (MVC), likely block HIV-1 through an allosteric, noncompetitive inhibition mechanism, whereas inhibition by agonists such as PSC-RANTES is less defined and may involve receptor removal by cell surface downregulation, competitive inhibition by occluding the HIV-1 envelope binding, and/or allosteric effects by altering CCR5 conformation. We explored the inhibitory mechanisms of maraviroc and PSC-RANTES by employing pairs of virus clones with differential sensitivities to these inhibitors. Intrinsic PSC-RANTES-resistant virus (YA versus RT) or those selected in PSC-RANTES treated macaques (M584 versus P3-4) only displayed resistance in multiple-cycle assays or with a CCR5 mutant that cannot be downregulated.

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Background: Vitamin B12 deficiency is prevalent in many countries of origin of refugees. Using a threshold of 5% above which a prevalence of low Vitamin B12 is indicative of a population health problem, we hypothesised that Vitamin B12 deficiency exceeds this threshold among newly-arrived refugees resettling in Australia, and is higher among women due to their increased risk of food insecurity. This paper reports Vitamin B12 levels in a large cohort of newly arrived refugees in five Australian states and territories.

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Maraviroc (MVC) is a CCR5 antagonist that inhibits HIV-1 entry by binding to the coreceptor and inducing structural alterations in the extracellular loops. In this study, we isolated MVC-resistant variants from an HIV-1 primary isolate that arose after 21 weeks of tissue culture passage in the presence of inhibitor. gp120 sequences from passage control and MVC-resistant cultures were cloned into NL4-3 via yeast-based recombination followed by sequencing and drug susceptibility testing.

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Sixth graders are at a prime age to modify behaviors and beliefs regarding exercise, nutrition, body image, and smoking. Empower U was created to change knowledge, beliefs, and behaviors regarding these topics. This pilot study utilized pre/post assessments of 58 sixth graders from a private middle school in the midsouth.

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Hypersusceptibility (HS) to inhibition by different antiretroviral drugs (ARVs) among diverse HIV-infected individuals may be a misnomer because clinical response to treatment is evaluated in relation to subtype B infections while drug susceptibility of the infecting virus, regardless of subtype, is compared to a subtype B HIV-1 laboratory strain (NL4-3 or IIIB). Mounting evidence suggests that HS to different ARVs may result in better treatment outcome just as drug resistance leads to treatment failure. We have identified key amino acid polymorphisms in the protease coding region of a non-B HIV-1 subtype linked to protease inhibitor HS, namely, 17E and 64M in CRF02_AG.

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The RNA response element TAR plays a critical role in HIV replication by providing a binding site for the recruitment of the viral transactivator protein Tat. Using a structure-guided approach, we have developed a series of conformationally-constrained cyclic peptides that act as structural mimics of the Tat RNA binding region and block Tat-TAR interactions at nanomolar concentrations in vitro. Here we show that these compounds block Tat-dependent transcription in cell-free systems and in cell-based reporter assays.

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Reports of potential drug-resistant strains of Plasmodium malariae in western Indonesia raise concerns that chloroquine resistance may be emerging in P. malariae and P. ovale.

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Entry inhibitors represent a new class of antiretroviral agents for the treatment of infection with HIV-1. While resistance to other HIV drug classes has been well described, resistance to this new class is still ill defined despite considerable clinical use. Several potential mechanisms have been proposed: tropism switching (utilization of CXCR4 instead of CCR5 for entry), increased affinity for the coreceptor, increased rate of virus entry into host cells, and utilization of inhibitor-bound receptor for entry.

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The purpose of this investigation was to conduct an analysis of a set of metrics developed for comparing features of software used in speech generating devices (SGD) for augmentative and alternative communication (AAC). These metrics - measures of speed, efficiency, and accuracy - were employed during a sentence reconstruction task. Twenty two participants without disabilities reconstructed nine sentences using each of three SGD software programs, counterbalanced to remove order effects.

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Amodiaquine retains efficacy against infection by chloroquine-resistant Plasmodium falciparum; however, little information is available on its efficacy against infection by chloroquine-resistant Plasmodium vivax. Patients presenting to a rural clinic with a pure P. vivax infection that recurred after recent antimalarial treatment were retreated, this time with amodiaquine monotherapy, and the risk of further recurrence within 4 weeks was assessed.

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Purpose: To report on data from the current survey about academic and clinical education in augmentative and alternative communication (AAC), as well as to compare these findings with earlier surveys in an attempt to identify any changes being made as programs in the United States implement the new certification standards of the American Speech-Language-Hearing Association in the area of speech-language pathology.

Method: A survey was sent to all speech-language pathology training programs in the United States via e-mail directed to program directors or faculty teaching in AAC.

Results: A total of 168 surveys were returned, for a return rate of 57.

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Dihydroartemisinin-piperaquine (DHP) is an important new treatment for drug-resistant malaria, although pharmacokinetic studies on the combination are limited. In Papua, Indonesia, we assessed determinants of the therapeutic efficacy of DHP for uncomplicated malaria. Plasma piperaquine concentrations were measured on day 7 and day 28, and the cumulative risk of parasitological failure at day 42 was calculated using survival analysis.

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Background: The burden of Plasmodium vivax infections has been underappreciated, especially in southeast Asia where chloroquine resistant strains have emerged. Our aim was to compare the safety and efficacy of dihydroartemisinin-piperaquine with that of artemether-lumefantrine in patients with uncomplicated malaria caused by multidrug-resistant P falciparum and P vivax.

Methods: 774 patients in southern Papua, Indonesia, with slide-confirmed malaria were randomly assigned to receive either artemether-lumefantrine or dihydroartemisinin-piperaquine and followed up for at least 42 days.

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