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1.
Front Psychol ; 12: 759270, 2021.
Article in English | MEDLINE | ID: mdl-34803842

ABSTRACT

Objective: Inhibitory control training (ICT) has shown promise for improving health behaviours, however, less is known about its mediators of effectiveness. The current paper reports whether ICT reduces smoking-related outcomes such as craving and nicotine dependence, increases motivation to quit and whether reductions in smoking or craving are mediated by response inhibition or a devaluation of smoking stimuli. Method: Adult smokers (minimum 10 cigarettes per day; N = 107, M age = 46.15 years, 57 female) were randomly allocated to receive 14 days of smoking-specific ICT (named INST; a go/no-go task where participants were trained to not respond to smoking stimuli) or active control training (participants inhibited responding toward neutral stimuli). Participants were followed up to 3-months post-intervention. This trial was preregistered (Australian and New Zealand Clinical Trials Registry ID: ACTRN12617000252314; URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=370204). Results: There were no significant differences between ICT and active control training groups. Specifically, participants in both groups showed significant reductions in craving, nicotine dependence, motivation and a devaluation (reduced evaluation) of smoking-stimuli up to 3-months follow-up compared to baseline. Inhibition and devaluation of smoking stimuli did not act as mediators. Devaluation of smoking stimuli was an independent predictor of smoking and craving at follow-up. Conclusion: Inhibitory control training (ICT) was no more effective at reducing smoking-related outcomes compared to the active control group, however, significant improvements in craving, dependence indicators and evaluation of smoking stimuli were observed across both groups. A return to basic experimental research may be required to understand the most effective ICT approach to support smoking cessation.

2.
Front Hum Neurosci ; 14: 25, 2020.
Article in English | MEDLINE | ID: mdl-32116609

ABSTRACT

Behavioral studies have shown that the ability to discriminate between non-native speech sounds improves after seeing how the sounds are articulated. This study examined the influence of visual articulatory information on the neural correlates of non-native speech sound discrimination. English speakers' discrimination of the Hindi dental and retroflex sounds was measured using the mismatch negativity (MMN) event-related potential, before and after they completed one of three 8-min training conditions. In an audio-visual speech training condition (n = 14), each sound was presented with its corresponding visual articulation. In one control condition (n = 14), both sounds were presented with the same visual articulation, resulting in one congruent and one incongruent audio-visual pairing. In another control condition (n = 14), both sounds were presented with the same image of a still face. The control conditions aimed to rule out the possibility that the MMN is influenced by non-specific audio-visual pairings, or by general exposure to the dental and retroflex sounds over the course of the study. The results showed that audio-visual speech training reduced the latency of the MMN but did not affect MMN amplitude. No change in MMN amplitude or latency was observed for the two control conditions. The pattern of results suggests that a relatively short audio-visual speech training session (i.e., 8 min) may increase the speed with which the brain processes non-native speech sound contrasts. The absence of a training effect on MMN amplitude suggests a single session of audio-visual speech training does not lead to the formation of more discrete memory traces for non-native speech sounds. Longer and/or multiple sessions might be needed to influence the MMN amplitude.

3.
J Consult Clin Psychol ; 87(9): 831-843, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31318233

ABSTRACT

OBJECTIVE: The high rates of illness and mortality associated with cigarette smoking necessitate the development of novel reduction and cessation treatments. Inhibitory control training (ICT) has recently emerged as a potentially efficacious intervention to reduce the consumption of alcohol and unhealthy food. This randomized controlled trial was the first to investigate the effect of Internet-delivered ICT on cigarette consumption in a community sample of heavy smokers. METHOD: For the present study, 107 adult smokers (mean age = 46.15 years; 57 female) who smoked a minimum of 10 cigarettes per day and met criteria for a moderate or severe tobacco use disorder were recruited. Participants were randomly allocated to receive go/no-go training in which either smoking stimuli (intervention) or nonsmoking stimuli (control) were paired with no-go signals and were instructed to complete 1 training session per day over a 2-week period. This trial was preregistered with the Australian and New Zealand Clinical Trials Registry (Trial ID: ACTRN12617000252314). RESULTS: We found no significant differences between conditions on percentage of days abstinent or daily cigarette consumption, although there was a significant decrease in daily cigarette consumption across both conditions. Further, we found no significant moderating effects of impulsivity on the relationship between cigarette consumption and the 2 tasks. CONCLUSIONS: Although participants in both conditions reduced their daily cigarette consumption, the intervention task was no more successful than the control task was in achieving cigarette abstinence or reduction. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Subject(s)
Cognitive Remediation/methods , Inhibition, Psychological , Self-Control , Smoking Cessation/methods , Smoking/therapy , Telemedicine/methods , Adult , Female , Humans , Male , Middle Aged , Treatment Outcome
4.
Drug Alcohol Depend ; 197: 335-343, 2019 04 01.
Article in English | MEDLINE | ID: mdl-30878884

ABSTRACT

BACKGROUND: Adolescence is a critical developmental period in the trajectory of nicotine dependence, highlighting the need for a greater understanding of the modifiable risk factors. An extensive body of research has found that trait impulsivity is associated with higher levels of adolescent smoking; however, findings have been mixed. The present study aimed to synthesise existing literature to determine the strength and nature of the relationship between the UPPS-P impulsive traits and both adolescent cigarette consumption and nicotine dependence. METHODS: Fifty-one studies were meta-analysed using a random effects model to determine the association between each UPPS-P impulsive trait and both adolescent cigarette consumption and nicotine dependence. Age, gender, ethnicity and sample type were examined as potential moderators. RESULTS: Cigarette consumption was positively associated with each UPPS-P impulsive trait (r's ranging from 0.17-0.20). There were an insufficient number of studies to meta-analyse the association between nicotine dependence and the UPPS-P impulsive traits. There were no significant moderation effects of age, gender, ethnicity or sample type. CONCLUSIONS: Findings suggest that each UPPS-P impulsive trait shares similar associations with adolescent cigarette consumption. Additional studies are needed to determine the relationship between adolescent nicotine dependence and impulsivity. As most adult smokers initiate during adolescence, targeting these impulsive traits via novel prevention and intervention strategies may assist in reducing the prevalence of smoking.


Subject(s)
Cigarette Smoking/psychology , Impulsive Behavior , Personality , Tobacco Use Disorder/psychology , Adolescent , Female , Humans , Male , Risk Factors
5.
BMC Public Health ; 18(1): 1226, 2018 Nov 03.
Article in English | MEDLINE | ID: mdl-30390646

ABSTRACT

BACKGROUND: Smoking is one of the leading preventable causes of illness and premature death worldwide. Despite a variety of effective treatments, relapse rates remain high, and novel, innovative interventions are needed in order to reduce the global prevalence of smoking. Research has indicated that deficits in the ability to inhibit a response (referred to as response inhibition) is a predictor of relapse and subsequently, targeting this potentially modifiable risk factor may lead to improvements in smoking outcomes. Indeed, in recent years, stimulus-specific response inhibition training has emerged as a potentially efficacious intervention to reduce unwanted/unhealthy behaviours such as alcohol and unhealthy food consumption. As such, the present trial is the first to evaluate the real-world efficacy of response inhibition smoking training (INST) in a sample of adult heavy smokers. METHODS/DESIGN: This randomised controlled trial will recruit nicotine dependent smokers aged between 18 and 60 using social media and advertisements in Victoria, Australia. The sample target was 150 to account for drop out and non-adherence. Once informed consent has been obtained, participants complete a range of baseline measures during a face to face interview. Participants are randomly allocated to one of two online training conditions: an intervention training group (INST), which requires participants to exercise response inhibition towards smoking-related stimuli; or an active control group, which requires participants to exercise response inhibition towards household items and does not include any smoking-related stimuli. They complete the first training session during the interview to ensure the training protocol is clear. Both groups are instructed to complete a further 13 training sessions (1 per day) at home on their computer and follow-up phone calls will be conducted at three time points: post-intervention, one-month and three months. The primary outcomes are: a) rates of smoking cessation and; b) reduction in the quantity of average daily smoking at post-intervention, one and three months follow-up. DISCUSSION: There is a pressing need to develop novel and innovative smoking interventions. If proven to be effective, INST could make a highly cost-effective contribution to improvements in smoking intervention outcomes. TRIAL REGISTRATION: The trial was prospectively registered with the Australian New Zealand Clinical Trials Registry 17th February 2017. Trial ID: ACTRN12617000252314 .


Subject(s)
Inhibition, Psychological , Smokers/psychology , Smoking Prevention/methods , Smoking/psychology , Adolescent , Adult , Female , Follow-Up Studies , Humans , Male , Middle Aged , Smokers/statistics & numerical data , Smoking Cessation/statistics & numerical data , Treatment Outcome , Victoria , Young Adult
6.
Med J Aust ; 208(1): 35-40, 2018 01 15.
Article in English | MEDLINE | ID: mdl-29320671

ABSTRACT

OBJECTIVES: Many women report declines in cognitive function during pregnancy, but attempts to empirically evaluate such changes have yielded inconsistent results. We aimed to determine whether pregnancy is associated with objective declines in cognitive functioning, and to assess the progression of any declines during pregnancy. STUDY DESIGN: We undertook a meta-analysis, applying a random effects model, of 20 studies that have reported quantitative relationships between pregnancy and changes in cognition. DATA SOURCES: Full text articles indexed by Cumulative Index to Nursing and Allied Health Literature (CINAHL) Complete, MEDLINE Complete, and PsychINFO. DATA SYNTHESIS: The 20 studies assessed included 709 pregnant women and 521 non-pregnant women. Overall cognitive functioning was poorer in pregnant women than in non-pregnant women (standardised mean difference [SMD], 0.52 [95% CI, 0.07-0.97]; P = 0.025). Analysis of cross-sectional studies found that general cognitive functioning (SMD, 1.28 [95% CI 0.26-2.30]; P = 0.014), memory (SMD, 1.47 [95% CI, 0.27-2.68]; P = 0.017), and executive functioning (SMD, 0.46 [95% CI, 0.03-0.89]; P = 0.036) were significantly reduced during the third trimester of pregnancy (compared with control women), but not during the first two trimesters. Longitudinal studies found declines between the first and second trimesters in general cognitive functioning (SMD, 0.29 [95% CI, 0.08-0.50]; P = 0.006) and memory (SMD, 0.33 [95% CI, 0.12-0.54]; P = 0.002), but not between the second and third trimesters. CONCLUSIONS: General cognitive functioning, memory, and executive functioning were significantly poorer in pregnant than in control women, particularly during the third trimester. The differences primarily develop during the first trimester, and are consistent with recent findings of long term reductions in brain grey matter volume during pregnancy. The impact of these effects on the quality of life and everyday functioning of pregnant women requires further investigation.


Subject(s)
Cognitive Dysfunction/epidemiology , Pregnancy Complications/epidemiology , Cross-Sectional Studies , Executive Function , Female , Humans , Memory , Pregnancy , Pregnancy Trimester, Third , Quality of Life
7.
Psychophysiology ; 54(9): 1393-1404, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28497557

ABSTRACT

This study compared the performance of a low-cost wireless EEG system to a research-grade EEG system on an auditory oddball task designed to elicit N200 and P300 ERP components. Participants were 15 healthy adults (6 female) aged between 19 and 40 (M = 28.56; SD = 6.38). An auditory oddball task was presented comprising 1,200 presentations of a standard tone interspersed by 300 trials comprising a deviant tone. EEG was simultaneously recorded from a modified Emotiv EPOC and a NeuroScan SynAmps RT EEG system. The modifications made to the Emotiv system included attaching research grade electrodes to the Bluetooth transmitter. Additional modifications enabled the Emotiv system to connect to a portable impedance meter. The cost of these modifications and portable impedance meter approached the purchase value of the Emotiv system. Preliminary analyses revealed significantly more trials were rejected from data acquired by the modified Emotiv compared to the SynAmps system. However, the ERP waveforms captured by the Emotiv system were found to be highly similar to the corresponding waveform from the SynAmps system. The latency and peak amplitude of N200 and P300 components were also found to be similar between systems. Overall, the results indicate that, in the context of an oddball task, the ERP acquired by a low-cost wireless EEG system can be of comparable quality to research-grade EEG acquisition equipment.


Subject(s)
Brain/physiology , Electroencephalography/methods , Evoked Potentials/physiology , Acoustic Stimulation , Adult , Electroencephalography/instrumentation , Evoked Potentials, Auditory/physiology , Female , Humans , Male , Young Adult
8.
Obes Surg ; 22(11): 1666-75, 2012 Nov.
Article in English | MEDLINE | ID: mdl-22669523

ABSTRACT

BACKGROUND: The Beck Depression Inventory (BDI) is one of the most commonly used instruments to assess depression in persons with obesity. While it has been validated in normal and psychiatric populations, in obese populations, its validity remains uncertain. This study aimed to investigate the validity and reliability of the BDI-IA and BDI-II in severely obese bariatric surgery candidates. METHODS: Consecutive new candidates at a bariatric surgery clinic were invited to participate in the study by their consulting surgeon. All candidates were assessed using the Structured Clinical Interview for DSM-IV Disorders (SCID-I); 118 completed the BDI-IA and 83 completed the BDI-II. Two hundred one patients (response rate, 88 %) participated in the study. The current sample (82 % female) had an average body mass index of 42.83 ± 6.34 and an average age of 45 ± 12 years. RESULTS: Based on the SCID-I, 54 candidates (26.9 %) met the criteria for a mood disorder, with 37 meeting the criteria for current major depressive disorder. Individuals diagnosed with a clinical mood disorder had significantly higher scores on the BDI (BDI-IA, 23.59 ± 9.69 vs. 12.76 ± 8.29; BDI-II, 22.93 ± 5.22 vs. 11.25 ± 8.44). Our results indicated that, as a screening tool for a clinical mood disorder, the BDI-II had an optimal cutoff of 13, with a sensitivity of 100 and specificity of 67.75. CONCLUSIONS: Results indicated that the BDI-IA should not be used as a tool to measure depressive symptomatology in obese bariatric surgery candidates. No cutoff was identified with adequate sensitivity and specificity, and over 20 % of patients were misclassified. As a screening tool for a clinical mood disorder, the BDI-II was adequate; however, prevalence rates were significantly overestimated.


Subject(s)
Bariatric Surgery , Mood Disorders/diagnosis , Mood Disorders/epidemiology , Obesity, Morbid/psychology , Patient Selection , Personality Inventory , Area Under Curve , Australia/epidemiology , Depression/diagnosis , Depression/epidemiology , Diagnostic and Statistical Manual of Mental Disorders , Female , Humans , Male , Middle Aged , Obesity, Morbid/surgery , Reproducibility of Results , Sensitivity and Specificity , Surveys and Questionnaires
9.
Int J Psychophysiol ; 84(2): 130-9, 2012 May.
Article in English | MEDLINE | ID: mdl-22342240

ABSTRACT

Central auditory processing in schizophrenia patients with a history of auditory hallucinations has been reported to be impaired, and abnormalities of interhemispheric transfer have been implicated in these patients. This study examined interhemispheric functional connectivity between auditory cortical regions, using temporal information obtained from latency measures of the auditory N1 evoked potential. Interhemispheric Transfer Times (IHTTs) were compared across 3 subject groups: schizophrenia patients who had experienced auditory hallucinations, schizophrenia patients without a history of auditory hallucinations, and normal controls. Pure tones and single-syllable words were presented monaurally to each ear, while EEG was recorded continuously. IHTT was calculated for each stimulus type by comparing the latencies of the auditory N1 evoked potential recorded contralaterally and ipsilaterally to the ear of stimulation. The IHTTs for pure tones did not differ between groups. For word stimuli, the IHTT was significantly different across the 3 groups: the IHTT was close to zero in normal controls, was highest in the AH group, and was negative (shorter latencies ipsilaterally) in the nonAH group. Differences in IHTTs may be attributed to transcallosal dysfunction in the AH group, but altered or reversed cerebral lateralization in nonAH participants is also possible.


Subject(s)
Acoustic Stimulation/methods , Auditory Cortex/physiology , Evoked Potentials, Auditory/physiology , Hallucinations/physiopathology , Reaction Time/physiology , Transfer, Psychology/physiology , Adult , Female , Hallucinations/diagnosis , Humans , Male , Middle Aged , Schizophrenia/diagnosis , Schizophrenia/physiopathology
10.
Obes Surg ; 21(3): 328-35, 2011 Mar.
Article in English | MEDLINE | ID: mdl-20559893

ABSTRACT

BACKGROUND: The Beck Depression Inventory (BDI) has been frequently employed as a measure of depression in studies of obesity, with the majority of studies reporting an improvement in scores following weight loss. Given the potential similarity in obesity-related and depressive symptoms, it is uncertain whether all components of depression would improve equally with weight loss. METHOD: The study included obese patients who had undergone laparoscopic adjustable gastric banding (LAGB) surgery and had completed BDIs at baseline and 1 year after surgery. Two groups of patients were included, a general background group (N = 191, mean age = 41 ± 9, mean BMI = 43 ± 8) and a group identified as experiencing elevated depressive symptoms based on BDI scores ≥23 (EDS group; (N = 67, mean age = 40 ± 9, mean BMI = 45 ± 7). RESULTS: Overall, BDI scores fell for both groups, background group at baseline 17 ± 9-8 ± 7 at 1 year and for the EDS group at baseline 30 ± 5-14 ± 10 at 1 year. Patient scores on the negative self-attitude subscale were significantly greater than the two other subscales and showed the greatest improvement 1 year following LAGB. Preexisting antidepressant therapy had little or no association on the BDI scores or on its change following weight loss. CONCLUSION: High rates of depression are continually reported in obesity, as is a remarkable decrease in depressive symptoms following weight loss. Negative attitudes towards one's self appears to be driving elevated BDI scores rather than the overlap in physical symptoms between obesity and depression.


Subject(s)
Body Image , Depression/epidemiology , Obesity, Morbid/epidemiology , Body Mass Index , Factor Analysis, Statistical , Gastroplasty , Humans , Obesity, Morbid/psychology , Obesity, Morbid/surgery , Quality of Life , Retrospective Studies
11.
Obes Facts ; 3(1): 7-14, 2010 Feb.
Article in English | MEDLINE | ID: mdl-20215790

ABSTRACT

AIMS: Patients' perceptions about weight-related stigma and discrimination were assessed in 2 groups of patients, obese and laparoscopic adjustable gastric banding (LAGB). METHODS: Seven focus group sessions were held including a total of 32 women, 8 obese (body mass index 35+) and 24 who had lost 50% of excess weight following bariatric surgery. During the sessions, participants were asked to consider their experiences in situations including general, family, friends, work place, medical, and educational settings. RESULTS: Whilst perceptions of discrimination and stigmatisation were common and affected many life situations, they were less prevalent than previous reports. It appeared that it was not the frequency or number of events which affected an individual but the intensity of the experience. Younger women reported greater discrimination than older women and felt the social consequences of obesity to a greater extent. Older women were more concerned about the consequences of being overweight on their health. CONCLUSIONS: Women who had lost weight considered that aspects of their own behaviours when obese contributed to their experiences of discrimination and stigmatisation. Perceptions of discrimination and stigmatisation appear to be influenced by age and current weight status.


Subject(s)
Obesity, Morbid/psychology , Perception/physiology , Prejudice , Stereotyping , Weight Loss/physiology , Adolescent , Adult , Age Factors , Aged , Bariatric Surgery , Female , Focus Groups , Humans , Middle Aged , Obesity, Morbid/surgery , Self Concept , Young Adult
12.
Obes Surg ; 20(4): 432-9, 2010 Apr.
Article in English | MEDLINE | ID: mdl-19760466

ABSTRACT

BACKGROUND: The Beck Depression Inventory (BDI) is frequently employed as measure of depression in studies of obesity. The aim of the study was to assess the factorial structure of the BDI in obese patients prior to bariatric surgery. METHODS: Confirmatory factor analysis was conducted on the current published factor analyses of the BDI. Three published models were initially analysed with two additional modified models subsequently included. A sample of 285 patients presenting for Lap-Band surgery was used. RESULTS: The published bariatric model by Munoz et al. was not an adequate fit to the data. The general model by Shafer et al. was a good fit to the data but had substantial limitations. The weight loss item did not significantly load on any factor in either model. A modified Shafer model and a proposed model were tested, and both were found to be a good fit to the data with minimal differences between the two. A proposed model, in which two items, weight loss and appetite, were omitted, was suggested to be the better model with good reliability. CONCLUSIONS: The previously published factor analysis in bariatric candidates by Munoz et al. was a poor fit to the data, and use of this factor structure should be seriously reconsidered within the obese population. The hypothesised model was the best fit to the data. The findings of the study suggest that the existing published models are not adequate for investigating depression in obese patients seeking surgery.


Subject(s)
Bariatric Surgery/psychology , Depression/diagnosis , Obesity/epidemiology , Psychiatric Status Rating Scales , Adult , Aged , Factor Analysis, Statistical , Female , Humans , Male , Middle Aged , Models, Statistical , Obesity/surgery , Young Adult
13.
Obesity (Silver Spring) ; 17(4): 698-705, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19148126

ABSTRACT

High levels of readiness to change (RTC) are considered critical to the long-term success of weight management programs including bariatric surgery. However, there are no data to support this assertion. We hypothesize that RTC level will not influence weight outcomes following surgery. In 227 consecutive patients undergoing adjustable gastric banding surgery, we recorded reasons for seeking surgery, and RTC measured with the University of Rhode Island Change Assessment. Scores were blinded until study completion. The primary outcome measure was percentage of excess BMI loss at 2 years (%EBMIL-2); others included compliance and surgical complications. Of 227 subjects, 204 (90%) had weight measurement at 2 years. There was no significant correlation between RTC score and %EBMIL-2 (r = 0.047, P = 0.5). Using the median split for RTC score the lowest 102 subjects mean %EBMIL-2 was 52.9 +/- 26.9% and the highest 52.2 +/- 28.3%, P = 0.869. There was no weight loss difference between highest and lowest quartiles, or a nonlinear relationship between weight loss and RTC score. There was no significant relationship between RCT score and compliance, or likelihood of complications. Those motivated by appearance were more likely to be younger women who lost more weight at 2 years. Poor attendance at follow-up visits was associated with less weight loss, especially in men. Measures of RTC did not predict weight loss, compliance, or surgical complications. Caution is advised when using assessments of RTC to predict outcomes of bariatric surgery.


Subject(s)
Bariatric Surgery/methods , Motivation , Obesity/psychology , Obesity/surgery , Patient Compliance/psychology , Weight Loss/physiology , Adult , Bariatric Surgery/adverse effects , Feeding Behavior/physiology , Feeding Behavior/psychology , Female , Follow-Up Studies , Health Surveys , Humans , Male , Middle Aged , Obesity/physiopathology , Outcome Assessment, Health Care , Predictive Value of Tests , Prospective Studies , Satiety Response/physiology
14.
Obesity (Silver Spring) ; 16(9): 2010-5, 2008 Sep.
Article in English | MEDLINE | ID: mdl-18497736

ABSTRACT

BACKGROUND: Depression and obesity, the two common ailments of modern society, are associated with increased risk of coronary artery disease and raised C-reactive protein (CRP) levels. Are the effects of depression and obesity related or do they influence CRP levels independently? OBJECTIVE: In 493 consecutive patients presenting for obesity surgery, we explored the relationship between symptoms of depression and raised CRP levels after controlling for confounding factors. METHODS AND PROCEDURES: Depression was measured using the Beck Depression Inventory (BDI). Confounding variables were age, gender, BMI, waist and hip measures, smoking and alcohol habits, medications, biochemical measures of the metabolic syndrome, and indirect measures of insulin resistance. General linear regression sought variables independently associated with CRP levels. RESULTS: These patients had a BMI range from 31 to 91 kg/m2, participants age ranged from 14 to 71 years, and 76% were women. The median CRP concentration was 7.7mg/l (interquartile range: 3.9-14), 40% had an abnormally raised concentration (> 10mg/l). The mean BDI score was 17.0 +/- 9.0, indicating symptoms of moderate depression. We found five independent factors associated with raised CRP levels. In order of strength of association, these were: higher BMI (beta = 0.36, P < 0.001), female gender (beta = -0.19, P < 0.001), estrogen therapy (beta = 0.18, P < 0.001), higher BDI score (beta = 0.11, P = 0.01), and insulin resistance index (beta = 0.11, P = 0.01), and with a combined R2 = 0.24, (P < 0.001). DISCUSSION: In obese patients, symptoms of depression were associated with raised CRP levels after controlling for confounding variables. Obese women on estrogen therapy are at risk of high CRP levels.


Subject(s)
C-Reactive Protein/metabolism , Depression/blood , Obesity/blood , Adolescent , Adult , Aged , Depression/psychology , Female , Humans , Male , Middle Aged , Obesity/psychology , Statistics, Nonparametric , Surveys and Questionnaires , Young Adult
16.
J Environ Qual ; 34(6): 2052-61, 2005.
Article in English | MEDLINE | ID: mdl-16221825

ABSTRACT

Atmospheric deposition of nitrogenous compounds to ombrotrophic peatlands (i.e., those that have peat layers higher than their surroundings and receive nutrients and minerals exclusively by precipitation) has the potential to significantly alter ecosystem functioning. This study utilized the acetylene inhibition technique to estimate the relative importance of denitrification in nitrogen removal from a primarily ombrotrophic peatland, in an attempt to estimate the threat of increased nitrogen loadings to these areas. Estimates of mean rates of denitrification ranged from -2.76 to 84.0 ng N(2)O-N cm(-3) h(-1) (equivalent to -150 to 4800 microg N(2)O-N m(-2) h(-1)) using an ex situ core technique and from -8.30 to 5.98 microg N(2)O-N m(-2) h(-1) using an in situ chamber technique. Core rates may have been elevated over natural field levels due to effects of disturbance on substrate availability, and chamber rates may have been low due to diffusional constraints on acetylene and N(2)O. Net nitrification was also measured in an attempt to evaluate this process as a source of nitrate for denitrifiers. The low rates of net nitrification measured, in combination with the low rates of in situ denitrification and the very low amounts of free nitrate measured in this peatland, suggests that inorganic N turnover in this wetland is low. Results showed that nitrate was a limiting factor for denitrification in this peatland, with mean rates from nitrate-amended cores ranging from 13.1 to 260 ng N(2)O-N cm(-3) h(-1), and it is expected that increases in nitrogen loadings will increase denitrification rates in this ecosystem.


Subject(s)
Nitrogen/metabolism , Soil , Acetylene/pharmacology , Ecosystem , Nitrates/analysis , Nitrates/metabolism , Nitrates/pharmacology , Nitrogen Oxides/metabolism , Quaternary Ammonium Compounds/analysis , Quaternary Ammonium Compounds/metabolism , Vermont
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