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  1. Article ; Online: A mathematical model of the within-host kinetics of SARS-CoV-2 neutralizing antibodies following COVID-19 vaccination.

    dePillis, Lisette / Caffrey, Rebecca / Chen, Ge / Dela, Mark D / Eldevik, Leif / McConnell, Joseph / Shabahang, Shahrokh / Varvel, Stephen A

    Journal of theoretical biology

    2022  Volume 556, Page(s) 111280

    Abstract: Compelling evidence continues to build to support the idea that SARS-CoV-2 Neutralizing Antibody (NAb) levels in an individual can serve as an important indicator of the strength of protective immunity against infection. It is not well understood why NAb ...

    Abstract Compelling evidence continues to build to support the idea that SARS-CoV-2 Neutralizing Antibody (NAb) levels in an individual can serve as an important indicator of the strength of protective immunity against infection. It is not well understood why NAb levels in some individuals remain high over time, while in others levels decline rapidly. In this work, we present a two-state mathematical model of within-host NAb dynamics in response to vaccination. By fitting only four host-specific parameters, the model is able to capture individual-specific NAb levels over time as measured by the AditxtScore™ for NAbs. The model can serve as a foundation for predicting NAb levels in the long-term, understanding connections between NAb levels, protective immunity, and breakthrough infections, and potentially guiding decisions about whether and when a booster vaccination may be warranted.
    MeSH term(s) Humans ; SARS-CoV-2 ; COVID-19/prevention & control ; COVID-19 Vaccines ; Antibodies, Viral ; Vaccination ; Antibodies, Neutralizing ; Models, Theoretical
    Chemical Substances COVID-19 Vaccines ; Antibodies, Viral ; Antibodies, Neutralizing
    Language English
    Publishing date 2022-10-04
    Publishing country England
    Document type Journal Article
    ZDB-ID 2972-5
    ISSN 1095-8541 ; 0022-5193
    ISSN (online) 1095-8541
    ISSN 0022-5193
    DOI 10.1016/j.jtbi.2022.111280
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: A Mathematical Model of the Within-Host Kinetics of SARS-CoV-2 Neutralizing Antibodies Following COVID-19 Vaccination

    de Pillis, Lisette / Caffrey, Rebecca / Chen, Ge / Dela, Mark D. / Eldevik, Leif / McConnell, Joseph / Shabahang, Shahrokh / Varvel, Stephen A.

    bioRxiv

    Abstract: Compelling evidence continues to build to support the idea that SARS-CoV-2 Neutralizing Antibody (NAb) levels in an individual can serve as an important indicator of the strength of protective immunity against infection. It is not well understood why NAb ...

    Abstract Compelling evidence continues to build to support the idea that SARS-CoV-2 Neutralizing Antibody (NAb) levels in an individual can serve as an important indicator of the strength of protective immunity against infection. It is not well understood why NAb levels in some individuals remain high over time, while in others levels decline rapidly. In this work, we present a two-population mathematical model of within-host NAb dynamics in response to vaccination. By fitting only four host-specific parameters, the model is able to capture individual-specific NAb levels over time as measured by the AditxtScore for NAbs. The model can serve as a foundation for predicting NAb levels in the long term, understanding connections between NAb levels, protective immunity, and breakthrough infections, and potentially guiding decisions about whether and when a booster vaccination may be warranted.
    Keywords covid19
    Language English
    Publishing date 2022-05-12
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2022.05.11.491557
    Database COVID19

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  3. Article ; Online: A Mathematical Model of the Within-Host Kinetics of SARS-CoV-2 Neutralizing Antibodies Following COVID-19 Vaccination

    dePillis, Lisette / Caffrey, Rebecca / Chen, Ge / Dela, Mark D. / Eldevik, Leif / McConnell, Joseph / Shabahang, Shahrokh / Varvel, Stephen A.

    bioRxiv

    Abstract: Compelling evidence continues to build to support the idea that SARS-CoV-2 Neutralizing Antibody (NAb) levels in an individual can serve as an important indicator of the strength of protective immunity against infection. It is not well understood why NAb ...

    Abstract Compelling evidence continues to build to support the idea that SARS-CoV-2 Neutralizing Antibody (NAb) levels in an individual can serve as an important indicator of the strength of protective immunity against infection. It is not well understood why NAb levels in some individuals remain high over time, while in others levels decline rapidly. In this work, we present a two-population mathematical model of within-host NAb dynamics in response to vaccination. By fitting only four host-specific parameters, the model is able to capture individual-specific NAb levels over time as measured by the AditxtScore for NAbs. The model can serve as a foundation for predicting NAb levels in the long term, understanding connections between NAb levels, protective immunity, and breakthrough infections, and potentially guiding decisions about whether and when a booster vaccination may be warranted.
    Keywords covid19
    Language English
    Publishing date 2022-05-12
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2022.05.11.491557
    Database COVID19

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  4. Article ; Online: Low-Density Lipoprotein Cholesterol Corrected for Lipoprotein(a) Cholesterol, Risk Thresholds, and Cardiovascular Events.

    Willeit, Peter / Yeang, Calvin / Moriarty, Patrick M / Tschiderer, Lena / Varvel, Stephen A / McConnell, Joseph P / Tsimikas, Sotirios

    Journal of the American Heart Association

    2020  Volume 9, Issue 23, Page(s) e016318

    Abstract: Background Conventional "low-density lipoprotein cholesterol (LDL-C)" assays measure cholesterol content in both low-density lipoprotein and lipoprotein(a) particles. To clarify the consequences of this methodological limitation for clinical care, our ... ...

    Abstract Background Conventional "low-density lipoprotein cholesterol (LDL-C)" assays measure cholesterol content in both low-density lipoprotein and lipoprotein(a) particles. To clarify the consequences of this methodological limitation for clinical care, our study aimed to compare associations of "LDL-C" and corrected LDL-C with risk of cardiovascular disease and to assess the impact of this correction on the classification of patients into guideline-recommended LDL-C categories. Methods and Results Lipoprotein(a) cholesterol content was estimated as 30% of lipoprotein(a) mass and subtracted from "LDL-C" to obtain corrected LDL-C values (LDL-C
    MeSH term(s) Adult ; Aged ; Cardiovascular Diseases/blood ; Cardiovascular Diseases/diagnosis ; Cardiovascular Diseases/epidemiology ; Cholesterol, LDL/blood ; Female ; Humans ; Lipoprotein(a)/blood ; Male ; Middle Aged ; Risk Factors
    Chemical Substances Cholesterol, LDL ; Lipoprotein(a)
    Language English
    Publishing date 2020-11-23
    Publishing country England
    Document type Journal Article ; Meta-Analysis ; Research Support, Non-U.S. Gov't
    ZDB-ID 2653953-6
    ISSN 2047-9980 ; 2047-9980
    ISSN (online) 2047-9980
    ISSN 2047-9980
    DOI 10.1161/JAHA.119.016318
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Lipoprotein(a) Mass Levels Increase Significantly According to

    Moriarty, Patrick M / Varvel, Stephen A / Gordts, Philip L S M / McConnell, Joseph P / Tsimikas, Sotirios

    Arteriosclerosis, thrombosis, and vascular biology

    2017  Volume 37, Issue 3, Page(s) 580–588

    Abstract: Objective: Lipoprotein(a) [Lp(a)] levels are genetically determined by hepatocyte apolipoprotein(a) synthesis, but catabolic pathways also influence circulating levels. : Conclusions: ... ...

    Abstract Objective: Lipoprotein(a) [Lp(a)] levels are genetically determined by hepatocyte apolipoprotein(a) synthesis, but catabolic pathways also influence circulating levels.
    Conclusions: APOE
    MeSH term(s) Adult ; Aged ; Apolipoprotein B-100/blood ; Apolipoproteins E/genetics ; Biomarkers/blood ; Cholesterol, LDL/blood ; Female ; Gene Frequency ; Genetic Association Studies ; Genotype ; Humans ; Lipoprotein(a)/blood ; Male ; Middle Aged ; Phenotype
    Chemical Substances APOB protein, human ; ApoE protein, human ; Apolipoprotein B-100 ; Apolipoproteins E ; Biomarkers ; Cholesterol, LDL ; Lipoprotein(a)
    Language English
    Publishing date 2017-01-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1221433-4
    ISSN 1524-4636 ; 1079-5642
    ISSN (online) 1524-4636
    ISSN 1079-5642
    DOI 10.1161/ATVBAHA.116.308704
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Are CB(1) Receptor Antagonists Nootropic or Cognitive Impairing Agents?

    Varvel, Stephen A / Wise, Laura E / Lichtman, Aron H

    Drug development research

    2010  Volume 70, Issue 8, Page(s) 555–565

    Abstract: For more than a decade, a considerable amount of research has examined the effects of rimonabant (SR 141716) and other CB(1) receptor antagonists in both in vivo and in vitro models of learning and memory. In addition to its utility in determining ... ...

    Abstract For more than a decade, a considerable amount of research has examined the effects of rimonabant (SR 141716) and other CB(1) receptor antagonists in both in vivo and in vitro models of learning and memory. In addition to its utility in determining whether the effects of drugs are mediated though a CB(1) receptor mechanism of action, these antagonists are useful in providing insight into the physiological function of the endogenous cannabinoid system. Several groups have reported that CB(1) receptor antagonists enhance memory duration in a variety of spatial and operant paradigms, but not in all paradigms. Conversely, disruption of CB(1) receptor signaling also impairs extinction learning in which the animal actively suppresses a learned response when reinforcement has been withheld. These extinction deficits occur in aversively motivated tasks, such as in fear conditioning or escape behavior in the Morris water maze task, but not in appetitively motivated tasks. Similarly, in electrophysiological models, CB(1) receptor antagonists elicit a variety of effects, including enhancement of long-term potentiation (LTP), while disrupting long-term depression (LTD) and interfering with transient forms of plasticity, including depolarization-induced suppression of inhibition (DSI) and depolarization-induced suppression of excitation (DSE). The collective results of the in vivo and in vitro studies employing CB(1) receptor antagonists, demonstrate that these receptors play integral roles in different components of cognitive processing. Functionally, pharmacological blockade of CB(1) receptors may strengthen memory duration, but interferes with extinction of learned behaviors that are associated with traumatic or aversive memories.
    Language English
    Publishing date 2010-06-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 604587-x
    ISSN 1098-2299 ; 0272-4391
    ISSN (online) 1098-2299
    ISSN 0272-4391
    DOI 10.1002/ddr.20334
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Comparative effects of an acute dose of fish oil on omega-3 fatty acid levels in red blood cells versus plasma: implications for clinical utility.

    Harris, William S / Varvel, Stephen A / Pottala, James V / Warnick, G Russell / McConnell, Joseph P

    Journal of clinical lipidology

    2013  Volume 7, Issue 5, Page(s) 433–440

    Abstract: Background: Omega-3 fatty acid (n-3 FA) biostatus can be estimated with red blood cell (RBC) membranes or plasma. The matrix that exhibits the lower within-person variability and is less affected by an acute dose of n-3 FA is preferred in clinical ... ...

    Abstract Background: Omega-3 fatty acid (n-3 FA) biostatus can be estimated with red blood cell (RBC) membranes or plasma. The matrix that exhibits the lower within-person variability and is less affected by an acute dose of n-3 FA is preferred in clinical practice.
    Objective: We compared the acute effects of a large dose of n-3 FA on RBC and plasma levels of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA).
    Methods: Healthy volunteers (n = 20) were given 4 capsules containing 3.6 g of n-3 FA with a standardized breakfast. Blood samples were drawn at 0, 2, 4, 6, 8, and 24 hours. The EPA + DHA content of RBC membranes and plasma (the latter expressed as a percentage of total FA and as a concentration) were determined. General linear mixed models were used to analyze the mean response profiles in FA changes over time for plasma and RBCs.
    Results: At 6 hours after load, the plasma concentration of EPA + DHA had increased by 47% (95% confidence interval [CI], 24% to 73%) and the plasma EPA + DHA percentage of total FA by 19% (95% CI, 4.7% to 36%). The RBC EPA + DHA percentage of composition was unchanged [-0.6% (95% CI, -2.6% to 1.5%)]. At 24 hours, the change in both of the plasma EPA + DHA markers was 10-fold greater than that in RBCs.
    Conclusions: An acute dose of n-3 FA (eg, a meal of oily fish or fish oil supplements) taken within a day before a doctor's visit can elevate levels of EPA + DHA in plasma, whether expressed as a percentage or a concentration, but not in RBC membranes. Similar to hemoglobin A1c, which is not affected by an acute glycemic deviation, RBCs provide a more reliable estimate of a patient's chronic EPA + DHA status than does plasma.
    MeSH term(s) Adult ; Blood Chemical Analysis/methods ; Docosahexaenoic Acids/blood ; Dose-Response Relationship, Drug ; Eicosapentaenoic Acid/blood ; Erythrocytes/drug effects ; Erythrocytes/metabolism ; Female ; Fish Oils/pharmacology ; Humans ; Male ; Plasma/drug effects ; Plasma/metabolism
    Chemical Substances Fish Oils ; Docosahexaenoic Acids (25167-62-8) ; Eicosapentaenoic Acid (AAN7QOV9EA)
    Language English
    Publishing date 2013-09
    Publishing country United States
    Document type Clinical Trial ; Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2365061-8
    ISSN 1876-4789 ; 1933-2874
    ISSN (online) 1876-4789
    ISSN 1933-2874
    DOI 10.1016/j.jacl.2013.05.001
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  8. Article: Lack of behavioral sensitization after repeated exposure to THC in mice and comparison to methamphetamine.

    Varvel, Stephen A / Martin, Billy R / Lichtman, Aron H

    Psychopharmacology

    2007  Volume 193, Issue 4, Page(s) 511–519

    Abstract: Rationale: Recent evidence has provided support for the incentive-sensitization model of addiction, where repeated stimulation of neural reward circuits leads to a long-lasting sensitization of mesolimbic dopaminergic activity. This phenomenon has been ... ...

    Abstract Rationale: Recent evidence has provided support for the incentive-sensitization model of addiction, where repeated stimulation of neural reward circuits leads to a long-lasting sensitization of mesolimbic dopaminergic activity. This phenomenon has been demonstrated with many drugs of abuse, most often by measuring progressively increased activating effects of drugs on locomotor activity, thought to reflect an underlying neural sensitization. Whether cannabinoids, and in particular Delta(9)-tetrahydrocannabinol (THC), produce similar effects in this model is somewhat controversial, with mixed evidence in the literature.
    Objectives: These experiments were conducted to determine whether behavioral sensitization could be established in mice after repeated exposure to THC. Sensitization to repeated methamphetamine treatment was used as a positive control.
    Methods: The effects of acute and repeated intermittent (every 3-4 days) treatment with THC or methamphetamine on locomotor activity were determined in Institute of Cancer Research (ICR) mice. Additional experiments with THC employed a dosing regimen that increased the number of injections, controlled for behavioral tolerance, examined different aspects of behavior, and used a different species (Sprague-Dawley rats).
    Results: Both methamphetamine and THC acutely increased activity. A robust dose-dependent sensitization was observed after intermittent treatment with methamphetamine but not with THC. Additionally, no evidence for behavioral sensitization to the effects of THC was found with any of the various protocols.
    Conclusion: These data suggest that repeated THC treatment is less likely to produce behavioral sensitization than are other drugs of abuse. It appears that this phenomenon may only occur under very particular conditions, which raises doubts about its relevance to chronic cannabis users.
    MeSH term(s) Animals ; Central Nervous System Stimulants/administration & dosage ; Central Nervous System Stimulants/pharmacology ; Dose-Response Relationship, Drug ; Dronabinol/administration & dosage ; Dronabinol/pharmacology ; Drug Administration Schedule ; Hallucinogens/administration & dosage ; Hallucinogens/pharmacology ; Male ; Methamphetamine/administration & dosage ; Methamphetamine/pharmacology ; Mice ; Mice, Inbred ICR ; Motor Activity/drug effects
    Chemical Substances Central Nervous System Stimulants ; Hallucinogens ; Methamphetamine (44RAL3456C) ; Dronabinol (7J8897W37S)
    Language English
    Publishing date 2007-05-12
    Publishing country Germany
    Document type Comparative Study ; Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 130601-7
    ISSN 1432-2072 ; 0033-3158
    ISSN (online) 1432-2072
    ISSN 0033-3158
    DOI 10.1007/s00213-007-0811-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: Biomarkers of cholesterol homeostasis in a clinical laboratory database sample comprising 667,718 patients.

    Dayspring, Thomas D / Varvel, Stephen A / Ghaedi, Leila / Thiselton, Dawn L / Bruton, James / McConnell, Joseph P

    Journal of clinical lipidology

    2015  Volume 9, Issue 6, Page(s) 807–816

    Abstract: Background: Circulating noncholesterol sterols/stanols (NCS) are used in clinical lipidology as surrogate measures of cholesterol synthesis and absorption, where they can be valuable tools in assessing cholesterol metabolism and personalizing therapies ... ...

    Abstract Background: Circulating noncholesterol sterols/stanols (NCS) are used in clinical lipidology as surrogate measures of cholesterol synthesis and absorption, where they can be valuable tools in assessing cholesterol metabolism and personalizing therapies in patients with dyslipidemia.
    Objectives: To describe the distributions of plasma NCS concentrations and inter-NCS correlations in a large cohort of American patients constituting a clinical laboratory database, and to investigate the relationship between circulating NCS, age, sex, and apolipoprotein E (APOE) genotype.
    Methods: A total of 667,718 patient blood samples submitted for testing to Health Diagnostic Laboratory, Inc. (Richmond, VA) were analyzed for cholesterol absorption markers (sitosterol, campesterol, and cholestanol) and one cholesterol synthesis marker (desmosterol). NCS percentiles were determined, along with intermarker correlations (Pearson's R). Analysis of variance was used to assess the effect of age and sex on NCS level, and to evaluate the relationship between cholesterol synthesis/absorption status and APOE genotype in a subset of 336,866 patients.
    Results: Mean NCS concentrations were: sitosterol, 2.45 μg/mL; campesterol, 3.3 μg/mL; cholestanol, 2.92 μg/mL; and desmosterol 0.99 μg/mL. The correlations between each NCS and its ratio to total cholesterol ranged from 0.72 (cholestanol) to 0.94 (desmosterol). NCS levels were significantly affected by age and sex (P < .0001), and prevalence of cholesterol hyperabsorption was higher in APOE ε4 allele carriers compared with the other APOE genotypes.
    Conclusions: We have described sample distributions of NCS biomarkers and characterized their relationship to age, sex, and APOE genotype. These data may facilitate research into altered cholesterol homeostasis and human disease, and help physicians optimize lipid-lowering therapies.
    MeSH term(s) Aging/blood ; Apolipoproteins E/genetics ; Biomarkers/blood ; Cholestanol/blood ; Cholestanol/metabolism ; Databases, Factual ; Dyslipidemias/blood ; Dyslipidemias/genetics ; Female ; Genotype ; Homeostasis ; Humans ; Laboratories ; Male ; Middle Aged ; Retrospective Studies ; Sex Characteristics
    Chemical Substances Apolipoproteins E ; Biomarkers ; Cholestanol (8M308U816E)
    Language English
    Publishing date 2015-11
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2365061-8
    ISSN 1876-4789 ; 1933-2874
    ISSN (online) 1876-4789
    ISSN 1933-2874
    DOI 10.1016/j.jacl.2015.08.003
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Exposure to marijuana smoke impairs memory retrieval in mice.

    Niyuhire, Floride / Varvel, Stephen A / Martin, Billy R / Lichtman, Aron H

    The Journal of pharmacology and experimental therapeutics

    2007  Volume 322, Issue 3, Page(s) 1067–1075

    Abstract: Marijuana (Cannabis sativa) and its primary psychoactive component, delta-9-tetrahydrocannabinol (Delta(9)-THC), have long been known to disrupt cognition in humans. Although Delta(9)-THC and other cannabinoids disrupt performance in a wide range of ... ...

    Abstract Marijuana (Cannabis sativa) and its primary psychoactive component, delta-9-tetrahydrocannabinol (Delta(9)-THC), have long been known to disrupt cognition in humans. Although Delta(9)-THC and other cannabinoids disrupt performance in a wide range of animal models of learning and memory, few studies have investigated the effects of smoked marijuana in these paradigms. Moreover, in preclinical studies, cannabinoids are generally administered before acquisition, and because retention is generally evaluated soon afterward, it is difficult to distinguish between processes related to acquisition and retrieval. In the present study, we investigated the specific effects of marijuana smoke and injected Delta(9)-THC on acquisition versus memory retrieval in a mouse repeated acquisition Morris water-maze task. To distinguish between these processes, subjects were administered Delta(9)-THC or they were exposed to marijuana smoke either 30 min before acquisition or 30 min before the retention test. Inhalation of marijuana smoke or injected Delta(9)-THC impaired the ability of the mice to learn the location of the hidden platform and to recall the platform location once learning had already taken place. In contrast, neither drug impaired performance in a cued task in which the platform was made visible. Finally, the cannabinoid-1 (CB(1)) receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl (rimonabant) blocked the memory disruptive effects of both Delta(9)-THC and marijuana. These data represent the first evidence demonstrating that marijuana impairs memory retrieval through a CB(1) receptor mechanism of action and independently of its effects on sensorimotor performance, motivation, and initial acquisition.
    MeSH term(s) Animals ; Dronabinol/pharmacology ; Drug Antagonism ; Marijuana Smoking/adverse effects ; Maze Learning/drug effects ; Memory/drug effects ; Mental Recall/drug effects ; Mice ; Receptor, Cannabinoid, CB1/antagonists & inhibitors ; Receptor, Cannabinoid, CB1/physiology
    Chemical Substances Receptor, Cannabinoid, CB1 ; Dronabinol (7J8897W37S)
    Language English
    Publishing date 2007-09
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 3106-9
    ISSN 1521-0103 ; 0022-3565
    ISSN (online) 1521-0103
    ISSN 0022-3565
    DOI 10.1124/jpet.107.119594
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