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Guyader ME, Warren LD, Green E, Butt C, Ivosev G, Kiesling RL, Schoenfuss HL, Higgins CP. Prioritizing potential endocrine active high resolution mass spectrometry (HRMS) features in Minnesota lakewater. Sci Total Environ 2019; 670:814-825. [PMID: 30921715 DOI: 10.1016/j.scitotenv.2019.02.448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 02/08/2019] [Accepted: 02/28/2019] [Indexed: 06/09/2023]
Abstract
Liquid chromatography high-resolution mass spectrometry (LC-HRMS) shows great potential for expanding our understanding of relevant unknown chemical components present within complex environmental mixtures. This study identified potentially endocrine active components within Minnesota lakewater by prioritizing LC-HRMS features uniquely present at sunfish spawning habitats where male fish showed signs of estrogen agonism. Porewater samples from four locations within the same lake were analyzed using liquid chromatography quadrupole time of flight mass spectrometry (LC-QToF/MS) with positive (ESI+) and negative (ESI-) electrospray ionization. Plasma vitellogenin concentrations of captured male sunfish was used to designate sites as either endocrine active (ACT; 2 sites) or reference (REF; 2 sites). Assuming unique chemical presence at active sites contributed to endocrine activity, features at significantly higher intensities (p-value < 0.05, t-value > t-critical, log-fold change > 0.1; equal variance t-test of log2 transformed data) in ACT sites were then compiled into a suspect search list for feature identification. Adducts and isotopes of prioritized features were deprioritized using pattern recognizing algorithms using mass, retention time, and intensity. Feature identities were reported according to established confidence metrics using spectral libraries and elemental composition algorithms. This LC-HRMS approach identified a number of features omitted by targeted analysis with higher relative abundances in ACT sites, including plant essential oils, fatty acids, and mycotoxins. Multivariate analysis determined whether features were either present at both sites (AB) or unique to individual ACT sites (A or B). Detection frequency across datasets indicated bias in feature prioritization influenced by the chosen sampling method and sample acquisition mode. The majority of features prioritized by this workflow remain tentatively identified or unidentified masses of interest, reflective of current limitations in shared spectral libraries for soft ionization analyses. Strategies similar to this workflow have the potential to reduce bias in database-driven toxicological prioritization frameworks.
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Castorina R, Bradman A, Stapleton HM, Butt C, Avery D, Harley KG, Gunier RB, Holland N, Eskenazi B. Current-use flame retardants: Maternal exposure and neurodevelopment in children of the CHAMACOS cohort. Chemosphere 2017; 189:574-580. [PMID: 28963974 PMCID: PMC6353563 DOI: 10.1016/j.chemosphere.2017.09.037] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 09/07/2017] [Accepted: 09/09/2017] [Indexed: 05/06/2023]
Abstract
Flame retardants are commonly used in consumer products found in U.S. households. Restrictions on the use of polybrominated diphenyl ether flame retardants have resulted in increased use of replacement chemicals, including Firemaster 550® (FM 550®) and organophosphate flame retardants (PFRs): tris(1,3- dichloro-2-propyl) phosphate (TDCIPP); tris(chloropropyl) phosphate (TCIPP); tris(2-chloroethyl) phosphate (TCEP); and triphenyl phosphate (TPHP). Animal research suggests that PFRs may affect neurodevelopment through noncholinergic mechanisms similar to some organophosphate (OP) pesticides. Despite the widespread presence of these compounds in home environments, and their structural similarity to neurotoxic OP pesticides, understanding of human exposure and health effects of PFRs is limited. We measured four urinary PFR metabolites from pregnant women in the CHAMACOS birth cohort study (n = 310) and assessed neurodevelopment of their children at age 7. Metabolites of TDCIPP (BDCIPP: bis(1,3-dichloro-2-propyl) phosphate) and TPHP (DPHP: diphenyl phosphate) were detected in >75% of urine samples, and isopropylphenyl phenyl phosphate (ip-PPP), a metabolite of one component of FM 550®, was detected in 72% of urine samples. We observed decreases of 2.9 points (95% Confidence Interval (CI): -6.3, 0.5) and 3.9 points (95% CI: -7.3,-0.5) in Full-Scale intelligence quotient and Working Memory, respectively, for each ten-fold increase in DPHP in adjusted regression models (n = 248). Decreases in Full-Scale IQ and Working Memory were greater in models of the molar sum of the PFR metabolites compared to the DPHP models. This is the first study to examine PFR and FM 550® exposures and potential neurodevelopmental outcomes in pregnant women and children. Additional research is warranted.
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Affiliation(s)
- Rosemary Castorina
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA.
| | - Asa Bradman
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
| | | | - Craig Butt
- Duke University, Nicholas School of the Environment, Durham, NC, USA
| | - Dylan Avery
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
| | - Kim G Harley
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
| | - Robert B Gunier
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
| | - Nina Holland
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
| | - Brenda Eskenazi
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
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Robel AE, Marshall K, Dickinson M, Lunderberg D, Butt C, Peaslee G, Stapleton HM, Field JA. Closing the Mass Balance on Fluorine on Papers and Textiles. Environ Sci Technol 2017; 51:9022-9032. [PMID: 28712295 DOI: 10.1021/acs.est.7b02080] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Papers and textiles that are treated with per- and polyfluoroalkyl substances (PFASs) are sources of human and environmental exposure. Data for individual PFASs, such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), are not placed into the context of total fluorine for papers and textiles. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to quantify volatile and ionic PFASs, respectively, and the total oxidizable precursor (TOP) assay was used to quantify precursors that form perfluoroalkyl carboxylates. Molar sums of PFASs obtained by GC-MS, LC-MS/MS, and precursors were compared to total fluorine (nmol F/cm2) determined by particle-induced gamma ray emission (PIGE) spectroscopy, measured before and after extraction. Volatile and ionic PFASs and unknown precursors accounted for 0-2.2%, 0-0.41%, and 0.021-14%, respectively, of the total nmol F/cm2 determined by PIGE. After extraction, papers and textiles retained 64 ± 28% to 110 ± 30% of the original nmol F/cm2 as determined by PIGE, indicating that the majority of fluorine remains associated with the papers and textiles. The sum of PFASs in the volatile, ionic, and precursor fraction, and total fluorine after extraction indicate that mass balance was achieved (within analytical error) of the initial total fluorine measured by PIGE.
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Affiliation(s)
- Alix E Robel
- Department of Environmental and Molecular Toxicology, 2750 Campus Way, Oregon State University , Corvallis, Oregon 97331, United States
| | - Kristin Marshall
- Department of Environmental and Molecular Toxicology, 2750 Campus Way, Oregon State University , Corvallis, Oregon 97331, United States
| | - Margaret Dickinson
- Science Center Rm 2106A , 35 East 12th Street, Holland, Michigan 49422-9000, United States
| | - David Lunderberg
- Science Center Rm 2106A , 35 East 12th Street, Holland, Michigan 49422-9000, United States
| | - Craig Butt
- Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
| | - Graham Peaslee
- Department of Physics, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Heather M Stapleton
- Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States
| | - Jennifer A Field
- Department of Environmental and Molecular Toxicology, 2750 Campus Way, Oregon State University , Corvallis, Oregon 97331, United States
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Castorina R, Butt C, Stapleton HM, Avery D, Harley KG, Holland N, Eskenazi B, Bradman A. Flame retardants and their metabolites in the homes and urine of pregnant women residing in California (the CHAMACOS cohort). Chemosphere 2017; 179:159-166. [PMID: 28365501 PMCID: PMC5491392 DOI: 10.1016/j.chemosphere.2017.03.076] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 03/17/2017] [Accepted: 03/18/2017] [Indexed: 05/18/2023]
Abstract
Organophosphate flame retardants (PFRs), used in consumer products since the 1970s, persist in the environment. Restrictions on penta-polybrominated diphenyl ether (PBDE) flame retardants resulted in increased use of Firemaster® 550 (FM® 550), and the organophosphate triesters: tris(1,3- dichloro-2-propyl) phosphate (TDCIPP); tris(chloropropyl) phosphate (TCIPP); tris(2-chloroethyl) phosphate (TCEP); and triphenyl phosphate (TPHP). The objectives of this study were to (1) identify determinants of flame retardants (4 PFRs, PentaBDEs and FM® 550) in house dust, (2) measure urinary PFR metabolites in pregnant women, and (3) estimate health risks from PFR exposure. We measured flame retardants in house dust (n = 125) and metabolites in urine (n = 310) collected in 2000-2001 from Mexican American women participating in the CHAMACOS birth cohort study in California. We detected FM® 550 and PFRs, including two (TCEP and TDCIPP) known to the state of California to cause cancer, in most dust samples. The maximum TCEP and TDCIPP dust levels were among the highest ever reported although the median levels were generally lower compared to other U.S. cohorts. Metabolites of TDCIPP (BDCIPP: bis(1,3-dichloro-2-propyl) phosphate) and TPHP (DPHP: diphenyl phosphate) were detected in 78% and 79% of prenatal urine samples, respectively. We found a weak but positive correlation between TPHP in dust and DPHP in 124 paired prenatal urine samples (Spearman rho = 0.17; p = 0.06). These results provide information on PFR exposure and risk in pregnant women from the early 2000's and are also valuable to assess trends in exposure and risk given changing fire safety regulations and concomitant changes in chemical flame retardant use.
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Affiliation(s)
- Rosemary Castorina
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, 1995 University Avenue, Suite 265, Berkeley, CA, 94704, USA.
| | - Craig Butt
- Duke University, Nicholas School of the Environment, 450 Research Drive, Durham, NC, 27519, USA
| | - Heather M Stapleton
- Duke University, Nicholas School of the Environment, 450 Research Drive, Durham, NC, 27519, USA
| | - Dylan Avery
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, 1995 University Avenue, Suite 265, Berkeley, CA, 94704, USA
| | - Kim G Harley
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, 1995 University Avenue, Suite 265, Berkeley, CA, 94704, USA
| | - Nina Holland
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, 1995 University Avenue, Suite 265, Berkeley, CA, 94704, USA
| | - Brenda Eskenazi
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, 1995 University Avenue, Suite 265, Berkeley, CA, 94704, USA
| | - Asa Bradman
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, 1995 University Avenue, Suite 265, Berkeley, CA, 94704, USA
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Abstract
Supernormality refers to the tendency to systematically deny the presence of common symptoms (e.g., intrusive thoughts). The current article describes the psychometric qualities of a 37-item self-report measure of supernormality (i.e., Supernormality Scale; SS). The SS was administered to nonclinical individuals (n=95), noncriminal psychiatric patients (n=28), nonpsychiatric delinquents (n=49), and a heterogeneous sample of forensic patients (n=59). Within the healthy control sample, some employees were instructed to feign supernormal behaviour, while others were asked to respond honestly to SS items. Findings indicate that the SS demonstrates adequate test-retest stability and internal consistency. In the forensic patient sample, elevated SS scores were significant related to denial of intrusive thoughts in a thought suppression paradigm. However, accuracy parameters for the SS (i.e., sensitivity and specificity) showed that there is room for improvement. Nevertheless, our findings indicate that the SS might be a useful research tool for measuring denial of common symptoms.
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Affiliation(s)
- M Cima
- Department of Psychology, Open University, Heerlen, The Netherlands.
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Cima M, Merckelbach H, Butt C, Kremer K, Knauer E, Schellbach-Matties R. It was not me: Attribution of blame for criminal acts in psychiatric offenders. Forensic Sci Int 2007; 168:143-7. [PMID: 16908110 DOI: 10.1016/j.forsciint.2006.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 02/24/2006] [Accepted: 07/06/2006] [Indexed: 11/23/2022]
Abstract
The current article addresses the psychometric qualities of the German Version of Gudjonsson's Blame Attribution Inventory (GBAI), a self-report scale for measuring attribution of blame for crime. The GBAI was administered to a criminal sample of forensic and criminal inmates (n=107). Findings indicate that the German version of the Gudjonsson Blame Attribution Inventory possesses acceptable test-retest stability and good internal consistency. Factor analysis reproduced the three basic dimensions of the GBAI: external attribution, mental-element attribution, and guilt-feeling attribution. Forensic patients had higher mental-element attribution and guilt-feeling attribution scores than the prison inmates. Interestingly, sexual offenders who were prisoners, showed the lowest guilt-feeling attribution, while sexual offenders who were forensic patients had the highest guilt-feeling attribution scores. Since earlier research reported a tendency of faking good in sexual offenders, we suggest that the forensic sexual offenders may demonstrate a social desirable response tendency in an attempt to gain sympathy and/or earlier parole. All in all, our data show that the German version of the GBAI is a valuable tool for measuring attributional styles of offenders.
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Affiliation(s)
- M Cima
- Department of Medical, Clinical and Experimental Psychology, Maastricht University, Universiteitssingel 50, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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Abstract
BACKGROUND Tumour necrosis factor alpha (TNFalpha) is a cytokine of critical importance in psoriatic arthritis. OBJECTIVES (1) To examine the association between TNFalpha promoter gene polymorphisms and psoriatic arthritis in two well characterised Canadian populations with the disease; (2) to carry out a meta-analysis of all TNFalpha association studies in white psoriatic arthritis populations. METHODS DNA samples were genotyped for five TNF variants by time of flight mass spectrometry using the Sequenom platform. All five single nucleotide polymorphisms were in the 5' flanking region of TNFalpha gene at the following positions: -1031 (T-->C), -863 (C-->A), -857 (C-->T), -308 (G-->A), and -238 (G-->A). Primary analyses were based on logistic regression. Summary estimates of disease/genotype relations from several studies were derived from random effects meta-analyses. RESULTS 237 psoriatic arthritis subjects and 103 controls from Newfoundland and 203 psoriatic arthritis subjects and 101 controls from Toronto were studied. A combined analysis of data from both populations, showed a significant association between disease status and the -238(A) variant (p=0.01). The meta-analysis estimate for the -238(A) TNFalpha variant in eight psoriatic arthritis populations was also significant (odds ratio=2.29 (95% confidence interval, 1.48 to 3.55)). CONCLUSIONS Analysis of TNFalpha variants in psoriatic arthritis populations shows that the -238 (A) variant is a significant risk factor for this disease.
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Affiliation(s)
- P Rahman
- St Clare's Mercy Hospital, Memorial University of Newfoundland, 1 South-154 LeMarchant Rd, St John's, Newfoundland, Canada A1C-5B8.
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Peddle L, Butt C, Snelgrove T, Rahman P. Interleukin (IL) 1alpha, IL1beta, IL receptor antagonist, and IL10 polymorphisms in psoriatic arthritis. Ann Rheum Dis 2005; 64:1093-4. [PMID: 15958769 PMCID: PMC1755570 DOI: 10.1136/ard.2004.031864] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Butt C, Sun S, Greenwood C, Gladman D, Rahman P. Lack of association of SLC22A4, SLC22A5, SLC9A3R1 and RUNX1 variants in psoriatic arthritis. Rheumatology (Oxford) 2005; 44:820-1. [PMID: 15769785 DOI: 10.1093/rheumatology/keh606] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Rahman P, Butt C, Siannis F, Farewell VT, Peddle L, Pellett FJ, Schentag C, Gladman DD. Association of SEEK1 and psoriatic arthritis in two distinct Canadian populations. Ann Rheum Dis 2005; 64:1370-2. [PMID: 15708881 PMCID: PMC1755628 DOI: 10.1136/ard.2004.031765] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To examine the relationship between SNP +39604 in SEEK1 and psoriatic arthritis (PsA) in two distinct Canadian populations. METHODS 103 patients with PsA and 105 ethnically matched controls from Newfoundland and 202 patients with PsA and 100 controls from Ontario were studied. Patients and controls were genotyped for SNP +39604 of SEEK1 by time of flight mass spectrometry, using the Sequenom platform. Genomic DNA was amplified by the Dynal RELI SSO HLA-Cw* typing kit for HLA-C typing. RESULTS The frequency of the minor SEEK1(T) allele in subjects with PsA and controls was 48.5% and 32.4%, respectively (odds ratio (OR) = 2.0; p = 0.017), in the Newfoundland population and 46.5% and 38.0%, respectively (OR = 1.4; p = 0.16), in the Ontario population. Although SEEK1 is associated with PsA, particularly in the Newfoundland population, multivariate analysis showed that SEEK1 does not seem to be a further susceptibility factor if the HLA-Cw*0602 status is already known. No association was noted between SEEK1(T) allele and onset of psoriasis, PsA, or arthritis pattern. CONCLUSION SEEK1 is associated with PsA in the Newfoundland founder population. This association is probably due to linkage disequilibrium between SEEK1 and HLA-Cw*0602 in this population.
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Affiliation(s)
- P Rahman
- St Clare's Mercy Hospital, Memorial University of Newfoundland, 1 South-154 LeMarchant Rd, St John's, Newfoundland, Canada A1C-5B8.
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Abstract
H9N2 influenza viruses are panzootic in domestic poultry in Eurasia and since 1999 have caused transient infections in humans and pigs. To investigate the zoonotic potential of H9N2 viruses, we studied the evolution of the viruses in live-poultry markets in Hong Kong in 2003. H9N2 was the most prevalent influenza virus subtype in the live-poultry markets between 2001 and 2003. Antigenic and phylogenetic analysis of hemagglutinin (HA) showed that all of the 19 isolates found except one belonged to the lineage represented by A/Duck/Hong Kong/Y280/97 (H9N2). The exception was A/Guinea fowl/NT184/03 (H9N2), whose HA is most closely related to that of the human isolate A/Guangzhou/333/99 (H9N2), a virus belonging to the A/Chicken/Beijing/1/94-like (H9N2) lineage. At least six different genotypes were recognized. The majority of the viruses had nonstructural (and HA) genes derived from the A/Duck/Hong Kong/Y280/97-like virus lineage but had other genes of mixed avian virus origin, including genes similar to those of H5N1 viruses isolated in 2001. Viruses of all six genotypes of H9N2 found were able to replicate in chickens and mice without adaptation. The infected chickens showed no signs of disease, but representatives of two viral genotypes were lethal to mice. Three genotypes of virus replicated in the respiratory tracts of swine, which shed virus for at least 5 days. These results show an increasing genetic and biologic diversity of H9N2 viruses in Hong Kong and support their potential role as pandemic influenza agents.
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Affiliation(s)
- Y K Choi
- Division of Virology, Department of Infectious Diseases, Mail Stop 330, St. Jude Children's Research Hospital, 332 N. Lauderdale, Memphis, TN 38105-2694, USA
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Abstract
The aim of this study was to investigate cardiovascular changes, particularly in forearm and calf blood flows, in response to acute emotional stress in men and women. The study was approved by the Ethics Committee of the Queen's Medical Centre, Nottingham University. Fifty-six healthy non-smokers (29 men and 27 women) aged 19 to 22 years participated. Blood flow was measured by venous occlusion plethysmography using mercury-in-silastic strain gauges. Acute emotional stress (2 min) was elicited by a visual orientation task. During acute emotional stress, there were increases in heart rate (males = 40 +/- 3%, females = 49 +/- 5%) and mean arterial pressure (males = 24 +/- 2%, females = 22 +/- 2%), and hyperaemia and vasodilatation were observed in the forearm (males = 162 +/- 15%, females = 239 +/- 31%) and calf (males = 78 +/- 16%, females = 131 +/- 24%). Vasoconstriction also occurred in some subjects. Forearm vasodilatation was significantly greater than calf vasodilatation. Gender variation was apparent in the calf, where vasodilatation was significantly greater in females, and vasoconstriction was significantly greater in males. In some subgroups of men and women, mean values indicated that acute emotional stress elicited increases in forearm, but not in calf, blood flows and vascular conductances. This pattern is similar to that reported by Rusch et al. (see text), but the present findings indicate that vasodilatation in the forearm and calf in response to acute emotional stress is more common.
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Affiliation(s)
- C Butt
- School of Biomedical Sciences, Queen's Medical Centre, Nottingham, UK
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Verleger R, Heide W, Butt C, Wascher E, Kömpf D. On-line brain potential correlates of right parietal patients' attentional deficit. Electroencephalogr Clin Neurophysiol 1996; 99:444-57. [PMID: 9020804 DOI: 10.1016/s0013-4694(96)95645-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
EEG potentials evoked by cues and targets were recorded in Posner's visual cueing task from 10 patients with lesions of the right parietal cortex and from age-matched healthy subjects. The patients' N1 component evoked by left-side cues was reduced at the right-parietal recording site, suggesting a general impairment in processing left-side visual input. As usual, patients' keypress responses were delayed when left targets were preceded by right cues. There were two correlates of this delay in the patients' EEG potentials evoked by the critical combination of right cue/left target: their mean amplitude 160-280 ms after target onset ('Nd') was less negative than with other combinations of cue and target, and the following frontal P300 was enhanced. The Nd reduction seems to be an on-line measure of patients' momentary decrease of attention for the left hemifield, while the frontal P300 might reflect the patients' attempts at reorienting. In conclusion, different components were sensitive to different aspects of the patients' disorder, suggesting the utility of this approach for developing detailed hypotheses on the mechanisms of attentional deficits involved in visual extinction and neglect.
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Affiliation(s)
- R Verleger
- Department of Neurology, Medical University, Lübeck, Germany
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Abstract
By recording event-related EEG potentials from patients with frontal, parietal, or temporo-parietal lesions, we wanted to determine the cortical area that is relevant to the P3b component, replicating the approach used by Knight and associates who found reduced P3bs in patients with temporo-parietal lesions. They used auditory and somatosensory stimuli. We wanted to replicate their findings in auditory and visual oddball tasks and analysed potentials evoked by targets and by standard stimuli. Temporo-parietal patients' P3bs were reduced with auditory targets and lacked a distinct Pz maximum with visual targets. Further, auditory N1 was reduced both with targets and standards, P3 to visual standards and P2 to auditory standards were reduced. Parietal patients' P3bs differed only slightly from the control group, being somewhat reduced over the lesioned hemisphere with visual stimuli. Their P3 to visual standards was, however, reduced to the same extent as was the temporo-parietal patients'. Frontal patients did not differ from the control group both in their P3b and in their P3 to standards but had a number of conspicuous features in modality-specific components. In sum, our results on P3b (as well as on N1) replicate Knight's findings, confirming his conclusion that integrity of the temporo-parietal junction is critical for P3b. Implications for hypotheses on P3 are discussed.
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Affiliation(s)
- R Verleger
- Department of Neurology, Medical University, Lübeck, FRG
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