15 results on '"David A. Nielsen"'
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2. Recent marine heatwaves in the North Pacific warming pool can be attributed to rising atmospheric levels of greenhouse gases
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Armineh Barkhordarian, David Marcolino Nielsen, and Johanna Baehr
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General Earth and Planetary Sciences ,General Environmental Science - Abstract
Over the last decade, the northeast Pacific experienced marine heatwaves that caused devastating marine ecological impacts with socioeconomic implications. Here we use two different attribution methods and show that forcing by elevated greenhouse gases levels has virtually certainly caused the multi-year persistent 2019–2021 marine heatwave. There is less than 1% chance that the 2019–2021 event with ~3 years duration and 1.6 ∘C intensity could have happened in the absence of greenhouse gases forcing. We further discover that the recent marine heatwaves are co-located with a systematically-forced outstanding warming pool, which we attribute to forcing by elevated greenhouse gases levels and the recent industrial aerosol-load decrease. The here-detected Pacific long-term warming pool is associated with a strengthening ridge of high-pressure system, which has recently emerged from the natural variability of climate system, indicating that they will provide favorable conditions over the northeast Pacific for even more severe marine heatwave events in the future.
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- 2022
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3. Tillage and residue management effects on irrigated maize performance and water cycling in a semiarid cropping system of Eastern Colorado
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Joel P. Schneekloth, Francisco J. Calderón, David C. Nielsen, and Steven J. Fonte
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Irrigation ,Crop residue ,0207 environmental engineering ,Soil Science ,04 agricultural and veterinary sciences ,02 engineering and technology ,Tillage ,Infiltration (hydrology) ,Water conservation ,Agronomy ,Evapotranspiration ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Cropping system ,020701 environmental engineering ,Agronomy and Crop Science ,Water content ,Water Science and Technology - Abstract
Residue removal from maize (Zea mays) fields offers an opportunity to increase farmer profits, but potential tradeoffs for water dynamics and crop performance merit further evaluation. This study, established in 2014, compared the effects of two tillage practices (no-till and conventional) and two residue management practices (harvested vs. kept in place) on maize grain yields, water infiltration, evapotranspiration, and soil physical attributes. On average, maize grain yields under limited irrigation increased with residue retention by 1.1 Mg ha−1 year−1 between 2016 and 2018, but tillage had no significant effect. Total infiltration (over 30 min) was higher with residue retention. Neither tillage nor residue management had a significant impact on evapotranspiration during the vegetative growth stage. However, there was a significant residue by tillage interaction where vegetative evapotranspiration was reduced by no-till and residue retention. Conversely, penetrometer resistance was significantly reduced by both tillage and residue retention. Volumetric water content in the soil profile at planting was higher with residue retention. These results suggest that plots with residue removal would on average require 60 mm year−1 of additional irrigation to attain the same yields as fields with residue retention. In summary, our findings suggest that high rates of crop residue removal under limited irrigation in a semiarid environment can negatively affect water conservation and yields, and that tradeoffs surrounding residue export need to be fully considered in land management and policy decisions.
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- 2020
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4. Effects of an MRI Try Without program on patient access
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David B Nielsen, Amie L Robinson, Barbra S. Rudder, Janelle R Noel-Macdonnell PhD, and Sara J Easley
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Male ,medicine.medical_specialty ,Time Factors ,Waiting Lists ,Sedation ,Conscious Sedation ,Neuroradiologist ,Sensitivity and Specificity ,Health Services Accessibility ,030218 nuclear medicine & medical imaging ,Cohort Studies ,Appointments and Schedules ,03 medical and health sciences ,0302 clinical medicine ,030225 pediatrics ,Chart review ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Medical physics ,Child ,Retrospective Studies ,Neuroradiology ,medicine.diagnostic_test ,business.industry ,Electronic medical record ,Magnetic resonance imaging ,Magnetic Resonance Imaging ,Wait time ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,Female ,medicine.symptom ,business ,Child life specialist - Abstract
Pediatric patients are often sedated for magnetic resonance imaging (MRI) scans to ensure images are of diagnostic quality. However, access time for MRIs requiring sedation is often long due to high patient volumes and limited sedation resources. This study examined the effectiveness of an MRI Try Without sedation program to decrease the wait time for obtaining an MRI while simultaneously ensuring diagnostic-quality images. A retrospective chart review was performed on subjects who utilized the MRI Try Without program from April 2014 through June 2015 at a dedicated pediatric institution. Child life specialist preparations and access time (i.e. time from exam ordered to exam completed) were recorded in each patient’s electronic medical record. MRI images were evaluated for image quality by a pediatric neuroradiologist. A total of 134 patients participated in the MRI Try Without program (mean age: 6.9±1.7 years), all of whom received interventions from a child life specialist. The average number of days between when the order was placed and when the MRI was completed using the MRI Try Without program was 15.4±18.5 days, while the third-available appointment for sedation/anesthesia was 46.2 days (standard deviation [SD]±15.7 days). Nearly all patients received a “good” or “very good” image quality determination (87.3%) and only 5 (3.8%) patients were recommended for repeat examination for diagnostic-quality images. Utilization of an MRI Try Without sedation program, with child life specialist interventions, decreased the wait time for obtaining an MRI while still providing diagnostic-quality images.
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- 2019
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5. Local indices for the South American monsoon system and its impacts on Southeast Brazilian precipitation patterns
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Andre L. Belem, David Marcolino Nielsen, Ana Luiza Spadano Albuquerque, and Marcio Cataldi
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Wet season ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Landslide ,Weather and climate ,010502 geochemistry & geophysics ,Convergence zone ,Monsoon ,01 natural sciences ,Natural hazard ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Precipitation ,South Atlantic Convergence Zone ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
The South American monsoon system (SAMS) plays a fundamental role in the precipitation regime of the most populous and economically important regions in Brazil. The South Atlantic Convergence Zone (SACZ) is a main component of the SAMS, characterizing its active phase, and is often associated with intense rainfall events: Strong and persistent episodes cause severe floods and landslides, while weak and sparse episodes are associated with droughts. The variability of the convergence zone caused great natural disasters in Southeast Brazil, associated with extreme precipitation conditions: 3562 landslides killed 947 people in Rio de Janeiro state in 2011, while a shortage of water in Sao Paulo affected around 20 million people between 2014 and 2015. In the present study, we build SACZ configuration series for the period between January 2000 and June 2014 and use them as indicators for the SAMS to quantify its influence on several atmospheric variables. Based on a principal component analysis, we present indices that identify the configuration of the SACZ in a local scale. The indices reached strong accuracy rates, especially for identifying days of extreme rainfall events associated with the SAMS and may, thus, serve as decision-making tools to help prepare for their impacts. Furthermore, the indices are composed by common variables simulated by numerical weather and climate models, other than precipitation, which is often a not very reliable output. The applied methodology is easily reproducible and different variables may be used to compose indices for different regions—an advantage of this local-scale approach.
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- 2016
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6. Ethnic diversity of DNA methylation in the OPRM1 promoter region in lymphocytes of heroin addicts
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Sara C. Hamon, Vadim Yuferov, Jurg Ott, David A. Nielsen, Colin Jackson, Ann Ho, and Mary Jeanne Kreek
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medicine.medical_specialty ,Methadone maintenance ,Receptors, Opioid, mu ,Pharmacology ,Biology ,White People ,Article ,Internal medicine ,mental disorders ,Ethnicity ,Genetics ,medicine ,Humans ,Lymphocyte Count ,Lymphocytes ,Gene ,Genetics (clinical) ,Endogenous opioid ,Heroin Dependence ,Promoter ,Hispanic or Latino ,Methylation ,DNA Methylation ,Black or African American ,Endocrinology ,CpG site ,Opioid ,DNA methylation ,Dinucleoside Phosphates ,medicine.drug - Abstract
The μ-opioid receptor is the site of action of many endogenous opioids as well as opiates. We hypothesize that differences in DNA methylation of specific CpG dinucleotides between former severe heroin addicts in methadone maintenance treatment and control subjects will depend, in part, upon ethnicity. DNA methylation analysis of the μ-opioid receptor gene (OPRM1) promoter region was performed on African-Americans (118 cases, 80 controls) and Hispanics (142 cases, 61 controls) and these were compared with a similar Caucasian cohort from our earlier study. In controls, a higher methylation level was found in the African-Americans compared with the Hispanics or Caucasians. Significant experiment-wise differences in methylation levels were found at the −25 and +12 CpG sites in the controls among the three ethnicities. The overall methylation level of the CpG sites were significantly higher in the former heroin addicts when compared with the controls (point-wise P = 0.0457). However, in the African-Americans, the degree of methylation was significantly decreased experiment-wise in the former heroin addicts at the +12 CpG site (P = 0.0032, Bonferroni corrected general estimating equations). In Hispanics, the degree of methylation was increased in the former heroin addicts at the −25 (P < 0.001, experiment-wise), −14 (P = 0.001, experiment-wise), and +27 (P < 0.001, experiment-wise) CpG sites. These changes in methylation of the OPRM1 promoter region may lead to altered expression of the μ-opioid receptor gene in the lymphocytes of former heroin addicts who are stabilized in methadone maintenance treatment.
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- 2010
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7. Estimating the cellular maintenance coefficient and its use in the design of two-phase partitioning bioscrubbers
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Sung Ho Yeom, Andrew J. Daugulis, and David R. Nielsen
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Volatile Organic Compounds ,Chemical oxygen demand ,Environmental engineering ,Oxygen transport ,chemistry.chemical_element ,Benzene ,Bioengineering ,General Medicine ,Models, Biological ,Oxygen ,Kinetics ,Bioreactors ,chemistry ,Achromobacter denitrificans ,Phase (matter) ,Alkanes ,Biomass ,Steady state (chemistry) ,Industrial and production engineering ,Aeration rate ,Biological system ,Benzene degradation ,Biotechnology - Abstract
One of the key roles of an organic solvent has emerged to be the enhancement of oxygen transfer in two-phase partitioning bioscrubbers (TPPBs). In order to determine an optimum organic fraction for a given VOCs loading, the oxygen demand of the total cell mass must be estimated, which depends upon the magnitude of the cellular maintenance coefficient. We have estimated the dynamics of the maintenance coefficient for benzene degradation by Achromobacter xylosoxidans Y234 in a TPPB and found that the maintenance coefficient generally decreased as cells accumulated in the TPPB but converged to a specific value of 1.750 x 10(-2) h(-1) at biological steady state. Due to its important influence on all of the essential design parameters of the TPPB system, including optimum organic fraction, aeration rate and agitation speed, the maintenance coefficient should be considered as a key biological determinant for microorganism selection, as well as in overall TPPB design.
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- 2009
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8. Increased OPRM1 DNA Methylation in Lymphocytes of Methadone-Maintained Former Heroin Addicts
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Sara C. Hamon, Vadim Yuferov, Ann Ho, Mary Jeanne Kreek, Colin Jackson, David A. Nielsen, and Jurg Ott
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Male ,medicine.medical_specialty ,Methadone maintenance ,Lymphocyte ,Molecular Sequence Data ,Receptors, Opioid, mu ,Pharmacology ,Biology ,White People ,Article ,Heroin ,Transcription (biology) ,Internal medicine ,mental disorders ,medicine ,Humans ,Lymphocytes ,Promoter Regions, Genetic ,Base Sequence ,Heroin Dependence ,Sequence Analysis, DNA ,Methylation ,DNA Methylation ,Psychiatry and Mental health ,medicine.anatomical_structure ,Endocrinology ,CpG site ,DNA methylation ,CpG Islands ,Female ,Methadone ,Software ,medicine.drug - Abstract
The mu-opioid receptor is the site of action of opiates and opioids. We examined whether there are differences in cytosine:guanine (CpG) dinucleotide methylation in the OPRM1 promoter between former heroin addicts and controls. We analyzed methylation at 16 CpG dinucleotides in DNA obtained from lymphocytes of 194 Caucasian former severe heroin addicts stabilized in methadone maintenance treatment and 135 Caucasian control subjects. Direct sequencing of bisulfite-treated DNA showed that the percent methylation at two CpG sites was significantly associated with heroin addiction. The level of methylation at the -18 CpG site was 25.4% in the stabilized methadone-maintained former heroin addicts and 21.4% in controls (p=0.0035, generalized estimating equations (GEE); p=0.0077, t-test; false discovery rate (FDR)=0.048), and the level of methylation at the +84 CpG dinucleotide site was 7.4% in cases and 5.6% in controls (p=0.0095, GEE; p=0.0067, t-test; FDR=0.080). Both the -18 and the +84 CpG sites are located in potential Sp1 transcription factor-binding sites. Methylation of these CpG sites may lead to reduced OPRM1 expression in the lymphocytes of these former heroin addicts.
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- 2008
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9. TPH2 and TPH1: Association of Variants and Interactions with Heroin Addiction
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Scott Kellogg, Sandra Barral, Dmitri Proudnikov, Jurg Ott, David A. Nielsen, Ann Ho, and Mary Jeanne Kreek
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Genetic Markers ,Male ,medicine.medical_specialty ,media_common.quotation_subject ,Black People ,rs1799913 ,Locus (genetics) ,Tryptophan Hydroxylase ,Severity of Illness Index ,White People ,Heroin ,Cohort Studies ,Reference Values ,Internal medicine ,mental disorders ,Genetics ,medicine ,Humans ,Allele frequency ,Genetics (clinical) ,Ecology, Evolution, Behavior and Systematics ,media_common ,TPH2 ,Heroin Dependence ,Addiction ,Haplotype ,Gene Amplification ,Genetic Variation ,Exons ,Hispanic or Latino ,Cohort ,Female ,Psychology ,medicine.drug - Abstract
The tryptophan hydroxylase 2 gene (TPH2) was resequenced at the 5′ upstream, coding, and 3′ downstream regions, including all 11 exons in 185 subjects. Twenty-three novel and 14 known variants were identified. In a cohort of 583 consecutively ascertained subjects, including normal volunteers and those with specific addictive diseases, six common TPH2 and one TPH1 variant were genotyped. Allele frequencies of three TPH2 variants and the TPH1 variant varied significantly among the four ethnic groups within the control subjects. Of these subjects, 385 who met heroin addiction or control criteria and were of Caucasian, African-American, or Hispanic ethnicity were examined for potential association with vulnerability to develop heroin addiction. At the two locus genotype level in Hispanics, the TPH1 rs1799913 variant was found to significantly interact with the TPH2 rs7963720 variant and heroin addiction (P = 0.022), and with the TPH2 rs4290270 variant and heroin addiction (P = 0.011). In the African-American group, a significant association of a specific TPH2 haplotype with heroin addiction also was found (SNPHAP, P = 0.004; PHASE P = 0.036).
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- 2008
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10. Direct estimation of the oxygen requirements of Achromobacter xylosoxidans for aerobic degradation of monoaromatic hydrocarbons (BTEX) in a bioscrubber
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David R. Nielsen, Andrew J. Daugulis, and P. James McLellan
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Time Factors ,Analytical chemistry ,chemistry.chemical_element ,Bioengineering ,Achromobacter ,BTEX ,Hydrocarbons, Aromatic ,Applied Microbiology and Biotechnology ,Oxygen ,Ethylbenzene ,chemistry.chemical_compound ,Bioreactors ,Biomass ,Benzene ,Biotransformation ,chemistry.chemical_classification ,biology ,General Medicine ,Achromobacter xylosoxidans ,biology.organism_classification ,Biodegradation, Environmental ,Hydrocarbon ,chemistry ,Production (computer science) ,Energy (signal processing) ,Biotechnology - Abstract
The O2 requirements for biomass production and supplying maintenance energy demands during the degradation of both benzene and ethylbenzene by Achromobacter xylosoxidans Y234 were measured using a newly proposed technique involving a bioscrubber. Using this approach, relevant microbial parameter estimates were directly and simultaneously obtained via linear regression of pseudo steady-state data. For benzene and ethylbenzene, the biomass yield on O2, \(Y_{X{\text{/O}}_{\text{2}} } \), was estimated on a cell dry weight (CDW) basis as 1.96 ±.25 mg CDW mgO2 and 0.98 ±.17 mg CDW mgO2, while the specific rate of O2 consumption for maintenance, \(m_{{\text{O}}_{\text{2}} } \), was estimated as 0.041 ±.008 mgO2 mg CDWh and 0.053 ±.022 mgO2 mg CDWh, respectively.
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- 2006
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11. Tryptophan hydroxylase and catechol-O-methyltransferase gene polymorphisms: relationships to monoamine metabolite concentrations in CSF of healthy volunteers
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David Goldman, David A. Nielsen, Gillian Spurlock, J. P. Gustavsson, Göran Sedvall, Erik G. Jönsson, Michael John Owen, and Markku Linnoila
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Adult ,Male ,medicine.medical_specialty ,Genotype ,Metabolite ,Tryptophan Hydroxylase ,Biology ,Catechol O-Methyltransferase ,Methoxyhydroxyphenylglycol ,chemistry.chemical_compound ,Cerebrospinal fluid ,Reference Values ,Polymorphism (computer science) ,Internal medicine ,medicine ,Humans ,Biogenic Monoamines ,Pharmacology (medical) ,Biological Psychiatry ,Sweden ,Polymorphism, Genetic ,Homovanillic acid ,Homovanillic Acid ,General Medicine ,Hydroxyindoleacetic Acid ,Middle Aged ,Tryptophan hydroxylase ,Psychiatry and Mental health ,Monoamine neurotransmitter ,Endocrinology ,chemistry ,Female ,Serotonin ,Polymorphism, Restriction Fragment Length - Abstract
Concentrations of monoamine metabolites (MM) in lumbar cerebrospinal fluid (CSF) have been used extensively as indirect estimates of monoamine turnover in the brain. We investigated possible relationships between DNA polymorphisms in the tryptophan hydroxylase (TPH) and catechol-O-methyltransferase (COMT) genes and CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy volunteers (n = 66). Lower CSF 5-HIAA levels were found in men with the TPH U allele (p = 0.005), but not in women. A similar but less significant pattern was observed for CSF HVA. No relationship was found between the TPH polymorphism and CSF MHPG. COMT genotypes did not relate significantly to MM concentrations. The results suggest that TPH genotypes participate differentially in the regulation of serotonin turnover rate under presumed steady state in the central nervous system of men. Due to the uncertain functional relevance of the DNA polymorphism investigated and the many calculations performed, the results should be interpreted with caution until replicated.
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- 1997
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12. Variation within the serotonin (5-HT) 5-HT2C receptor system aligns with vulnerability to cocaine cue reactivity
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Robert G. Fox, Shijing Liu, Noelle C. Anastasio, Sara C. Hamon, Scott D. Lane, Kathryn A. Cunningham, Lorena Maili, Se Swinford, David A. Nielsen, and Frederick G. Moeller
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Agonist ,0303 health sciences ,medicine.drug_class ,Addiction ,media_common.quotation_subject ,Attentional bias ,medicine.disease ,3. Good health ,Cocaine dependence ,5-HT2C receptor ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Psychiatry and Mental health ,0302 clinical medicine ,Cue reactivity ,medicine ,Prefrontal cortex ,Psychology ,Neuroscience ,030217 neurology & neurosurgery ,Biological Psychiatry ,030304 developmental biology ,Stroop effect ,media_common - Abstract
Cocaine dependence remains a challenging public health problem with relapse cited as a major determinant in its chronicity and severity. Environmental contexts and stimuli become reliably associated with its use leading to durable conditioned responses (‘cue reactivity') that can predict relapse as well as treatment success. Individual variation in the magnitude and influence of cue reactivity over behavior in humans and animals suggest that cue-reactive individuals may be at greater risk for the progression to addiction and/or relapse. In the present translational study, we investigated the contribution of variation in the serotonin (5-HT) 5-HT2C receptor (5-HT2CR) system in individual differences in cocaine cue reactivity in humans and rodents. We found that cocaine-dependent subjects carrying a single nucleotide polymorphism (SNP) in the HTR2C gene that encodes for the conversion of cysteine to serine at codon 23 (Ser23 variant) exhibited significantly higher attentional bias to cocaine cues in the cocaine-word Stroop task than those carrying the Cys23 variant. In a model of individual differences in cocaine cue reactivity in rats, we identified that high cocaine cue reactivity measured as appetitive approach behavior (lever presses reinforced by the discrete cue complex) correlated with lower 5-HT2CR protein expression in the medial prefrontal cortex and blunted sensitivity to the suppressive effects of the selective 5-HT2CR agonist WAY163909. Our translational findings suggest that the functional status of the 5-HT2CR system is a mechanistic factor in the generation of vulnerability to cocaine-associated cues, an observation that opens new avenues for future development of biomarker and therapeutic approaches to suppress relapse in cocaine dependence.
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- 2014
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13. Erratum: Increased OPRM1 DNA Methylation in Lymphocytes of Methadone
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Vadim Yuferov, Ann Ho, Mary Jeanne Kreek, David A. Nielsen, Colin Jackson, Sara C. Hamon, and Jurg Ott
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Pharmacology ,Lymphoblast ,Biology ,Molecular biology ,Psychiatry and Mental health ,chemistry.chemical_compound ,chemistry ,Cell culture ,DNA methylation ,Monoamine Oxidase A Gene ,medicine ,DNA ,Methadone ,medicine.drug - Abstract
Correction to: Neuropsychopharmacology advance online publication, 23 July 2008; doi:10.1038/npp.2008.108 In this article, on page 1, right column, second paragraph, line 11, an error occurred in the sentence beginning with ‘In human lymphoblast cell lines, average overall DNA….’ The sentence shouldread as follows: ‘In human lymphoblast cell lines, average overall DNA methylation at the monoamine oxidase A gene promoter was found….
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- 2009
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14. Correspondence
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C.M. Mazzanti, David Goldman, Markku Linnoila, and David A. Nielsen
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Pharmacology ,medicine.medical_specialty ,biology ,Membrane transport protein ,Cell biology ,Psychiatry and Mental health ,Membrane glycoproteins ,Endocrinology ,Carrier protein ,Internal medicine ,biology.protein ,medicine ,Serotonin ,Serotonin transporter ,Function (biology) - Published
- 1999
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15. Lesser peachtree borer: Influence of pheromone concentration, isomeric blend, and experimental design on trap capture
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David G. Nielsen and Foster Forbes Purrington
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biology ,Analytical chemistry ,General Medicine ,Trap (plumbing) ,biology.organism_classification ,Pheromone trap ,Biochemistry ,Sesiidae ,Sex pheromone ,Synanthedon pictipes ,Botany ,Trap density ,Pheromone ,Ecology, Evolution, Behavior and Systematics - Abstract
Trap capture data from Ohio and Wisconsin show that (E,Z)-3-13-octadecadien-1-ol acetate alone is an effective trap bait for maleSynanthedon pictipes (Grote and Robinson). Attractiveness increased by increasing attractant concentration but not by adding theZ,E geometrical isomer.S. pictipes males partitioned themselves in a linear fashion among traps baited with 10–100 μg of attractant in 10-μg increments. Furthermore, they discriminated between 50- and 100-μg baits placed in the same tree. These and other results indicate that, in clearwing experiments involving noninhibitory compounds and blend tuning, high trap density can be used successfully.
- Published
- 1980
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