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1.
Lars Michels Kerstin Bucher Rafael Lüchinger Peter Klaver Ernst Martin Daniel Jeanmonod Daniel Brandeis 《PloS one》2010,5(4)
Background
EEG studies of working memory (WM) have demonstrated load dependent frequency band modulations. FMRI studies have localized load modulated activity to the dorsolateral prefrontal cortex (DLPFC), medial prefrontal cortex (MPFC), and posterior parietal cortex (PPC). Recently, an EEG-fMRI study found that low frequency band (theta and alpha) activity negatively correlated with the BOLD signal during the retention phase of a WM task. However, the coupling of higher (beta and gamma) frequencies with the BOLD signal during WM is unknown.Methodology
In 16 healthy adult subjects, we first investigated EEG-BOLD signal correlations for theta (5–7 Hz), alpha1 (8–10), alpha2 (10–12 Hz), beta1 (13–20), beta2 (20–30 Hz), and gamma (30–40 Hz) during the retention period of a WM task with set size 2 and 5. Secondly, we investigated whether load sensitive brain regions are characterised by effects that relate frequency bands to BOLD signals effects.Principal Findings
We found negative theta-BOLD signal correlations in the MPFC, PPC, and cingulate cortex (ACC and PCC). For alpha1 positive correlations with the BOLD signal were found in ACC, MPFC, and PCC; negative correlations were observed in DLPFC, PPC, and inferior frontal gyrus (IFG). Negative alpha2-BOLD signal correlations were observed in parieto-occipital regions. Beta1-BOLD signal correlations were positive in ACC and negative in precentral and superior temporal gyrus. Beta2 and gamma showed only positive correlations with BOLD, e.g., in DLPFC, MPFC (gamma) and IFG (beta2/gamma). The load analysis revealed that theta and—with one exception—beta and gamma demonstrated exclusively positive load effects, while alpha1 showed only negative effects.Conclusions
We conclude that the directions of EEG-BOLD signal correlations vary across brain regions and EEG frequency bands. In addition, some brain regions show both load sensitive BOLD and frequency band effects. Our data indicate that lower as well as higher frequency brain oscillations are linked to neurovascular processes during WM. 相似文献2.
Background
Designing effective public health campaigns in areas of armed conflict requires a nuanced understanding of how violence impacts the epidemiology of the disease in question.Methods
We examine the geographical relationship between violence (represented by the location of detonated Improvised Explosive Devices) and polio incidence by generating maps of IEDs and polio incidence during 2010, and by comparing the mean number of IED detonations in polio high-risk districts with non polio high-risk districts during 2004–2009.Results
We demonstrate a geographic relationship between IED violence and incident polio. Districts that have high-risk for polio have highly statistically significantly greater mean numbers of IEDs than non polio high-risk districts (p-values 0.0010–0.0404).Conclusions
The geographic relationship between armed conflict and polio incidence provides valuable insights as to how to plan a vaccination campaign in violent contexts, and allows us to anticipate incident polio in the regions of armed conflict. Such information permits vaccination planners to engage interested armed combatants to co-develop strategies to mitigate the effects of violence on polio. 相似文献3.
Colleen A. Hanlon Melanie Canterberry Joseph J. Taylor William DeVries Xingbao Li Truman R. Brown Mark S. George 《PloS one》2013,8(7)
Background
The prefrontal cortex (PFC) is an anatomically and functionally heterogeneous area which influences cognitive and limbic processing through connectivity to subcortical targets. As proposed by Alexander et al. (1986) the lateral and medial aspects of the PFC project to distinct areas of the striatum in parallel but functionally distinct circuits. The purpose of this preliminary study was to determine if we could differentially and consistently activate these lateral and medial cortical-subcortical circuits involved in executive and limbic processing though interleaved transcranial magnetic stimulation (TMS) in the MR environment.Methods
Seventeen healthy individuals received interleaved TMS-BOLD imaging with the coil positioned over the dorsolateral (EEG: F3) and ventromedial PFC (EEG: FP1). BOLD signal change was calculated in the areas directly stimulated by the coil and in subcortical regions with afferent and efferent connectivity to the TMS target areas. Additionally, five individuals were tested on two occasions to determine test-retest reliability.Results
Region of interest analysis revealed that TMS at both prefrontal sites led to significant BOLD signal increases in the cortex under the coil, in the striatum, and the thalamus, but not in the visual cortex (negative control region). There was a significantly larger BOLD signal change in the caudate following medial PFC TMS, relative to lateral TMS. The hippocampus in contrast was significantly more activated by lateral TMS. Post-hoc voxel-based analysis revealed that within the caudate the location of peak activity was in the ventral caudate following medial TMS and the dorsal caudate following lateral TMS. Test-retest reliability data revealed consistent BOLD responses to TMS within each individual but a large variation between individuals.Conclusion
These data demonstrate that, through an optimized TMS/BOLD sequence over two unique prefrontal targets, it is possible to selectively interrogate the patency of these established cortical-subcortical networks in healthy individuals, and potentially patient populations. 相似文献4.
Michael Czisch Renate Wehrle Andrea Stiegler Henning Peters Katia Andrade Florian Holsboer Philipp G. S?mann 《PloS one》2009,4(8)
Background
A condition vital for the consolidation and maintenance of sleep is generally reduced responsiveness to external stimuli. Despite this, the sleeper maintains a level of stimulus processing that allows to respond to potentially dangerous environmental signals. The mechanisms that subserve these contradictory functions are only incompletely understood.Methodology/Principal Findings
Using combined EEG/fMRI we investigated the neural substrate of sleep protection by applying an acoustic oddball paradigm during light NREM sleep. Further, we studied the role of evoked K-complexes (KCs), an electroencephalographic hallmark of NREM sleep with a still unknown role for sleep protection. Our main results were: (1) Other than in wakefulness, rare tones did not induce a blood oxygenation level dependent (BOLD) signal increase in the auditory pathway but a strong negative BOLD response in motor areas and the amygdala. (2) Stratification of rare tones by the presence of evoked KCs detected activation of the auditory cortex, hippocampus, superior and middle frontal gyri and posterior cingulate only for rare tones followed by a KC. (3) The typical high frontocentral EEG deflections of KCs were not paralleled by a BOLD equivalent.Conclusions/Significance
We observed that rare tones lead to transient disengagement of motor and amygdala responses during light NREM sleep. We interpret this as a sleep protective mechanism to delimit motor responses and to reduce the sensitivity of the amygdala towards further incoming stimuli. Evoked KCs are suggested to originate from a brain state with relatively increased stimulus processing, revealing an activity pattern resembling novelty processing as previously reported during wakefulness. The KC itself is not reflected by increased metabolic demand in BOLD based imaging, arguing that evoked KCs result from increased neural synchronicity without altered metabolic demand. 相似文献5.
Daniela Dentico Fabio Ferrarelli Brady A. Riedner Richard Smith Corinna Zennig Antoine Lutz Giulio Tononi Richard J. Davidson 《PloS one》2016,11(2)
Study Objectives
We have recently shown higher parietal-occipital EEG gamma activity during sleep in long-term meditators compared to meditation-naive individuals. This gamma increase was specific for NREM sleep, was present throughout the entire night and correlated with meditation expertise, thus suggesting underlying long-lasting neuroplastic changes induced through prolonged training. The aim of this study was to explore the neuroplastic changes acutely induced by 2 intensive days of different meditation practices in the same group of practitioners. We also repeated baseline recordings in a meditation-naive cohort to account for time effects on sleep EEG activity.Design
High-density EEG recordings of human brain activity were acquired over the course of whole sleep nights following intervention.Setting
Sound-attenuated sleep research room.Patients or Participants
Twenty-four long-term meditators and twenty-four meditation-naïve controls.Interventions
Two 8-h sessions of either a mindfulness-based meditation or a form of meditation designed to cultivate compassion and loving kindness, hereafter referred to as compassion meditation.Measurements and Results
We found an increase in EEG low-frequency oscillatory activities (1–12 Hz, centered around 7–8 Hz) over prefrontal and left parietal electrodes across whole night NREM cycles. This power increase peaked early in the night and extended during the third cycle to high-frequencies up to the gamma range (25–40 Hz). There was no difference in sleep EEG activity between meditation styles in long-term meditators nor in the meditation naïve group across different time points. Furthermore, the prefrontal-parietal changes were dependent on meditation life experience.Conclusions
This low-frequency prefrontal-parietal activation likely reflects acute, meditation-related plastic changes occurring during wakefulness, and may underlie a top-down regulation from frontal and anterior parietal areas to the posterior parietal and occipital regions showing chronic, long-lasting plastic changes in long-term meditators. 相似文献6.
Graph Theoretical Analysis of BOLD Functional Connectivity during Human Sleep without EEG Monitoring
Background
Functional brain networks of human have been revealed to have small-world properties by both analyzing electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) time series.Methods & Results
In our study, by using graph theoretical analysis, we attempted to investigate the changes of paralimbic-limbic cortex between wake and sleep states. Ten healthy young people were recruited to our experiment. Data from 2 subjects were excluded for the reason that they had not fallen asleep during the experiment. For each subject, blood oxygen level dependency (BOLD) images were acquired to analyze brain network, and peripheral pulse signals were obtained continuously to identify if the subject was in sleep periods. Results of fMRI showed that brain networks exhibited stronger small-world characteristics during sleep state as compared to wake state, which was in consistent with previous studies using EEG synchronization. Moreover, we observed that compared with wake state, paralimbic-limbic cortex had less connectivity with neocortical system and centrencephalic structure in sleep.Conclusions
In conclusion, this is the first study, to our knowledge, has observed that small-world properties of brain functional networks altered when human sleeps without EEG synchronization. Moreover, we speculate that paralimbic-limbic cortex organization owns an efficient defense mechanism responsible for suppressing the external environment interference when humans sleep, which is consistent with the hypothesis that the paralimbic-limbic cortex may be functionally disconnected from brain regions which directly mediate their interactions with the external environment. Our findings also provide a reasonable explanation why stable sleep exhibits homeostasis which is far less susceptible to outside world. 相似文献7.
Objectives
Combat stress can be followed by persistent emotional consequences. It is thought that these emotional consequences are caused in part by increased amygdala reactivity. It is also thought that amygdala hyper-reactivity results from decreased inhibition from portions of the anterior cingulate cortex (ACC) in which activity is negatively correlated with activity in the amygdala. However, experimental support for these proposals has been inconsistent.Methods
We showed movies of combat and civilian scenes during a functional magnetic resonance imaging (fMRI) session to 50 veterans of recent combat. We collected skin conductance responses (SCRs) as measures of emotional arousal. We examined the relation of blood oxygenation-level dependent (BOLD) signal in the amygdala and ACC to symptom measures and to SCRs.Results
Emotional arousal, as measured with SCR, was greater during the combat movie than during the civilian movie and did not depend on symptom severity. As expected, amygdala signal during the less-arousing movie increased with increasing symptom severity. Surprisingly, during the more-arousing movie amygdala signal decreased with increasing symptom severity. These differences led to the unexpected result that amygdala signal in highly symptomatic subjects was lower during the more-arousing movie than during the less-arousing movie. Also unexpectedly, we found no significant inverse correlation between any portions of the amygdala and ACC. Rather, signal throughout more than 80% of the ACC showed a strong positive correlation with signal throughout more than 90% of the amygdala.Conclusions
Amygdala reactivity can be tuned bi-directionally, either up or down, in the same person depending on the stimulus and the degree of post-traumatic symptoms. The exclusively positive correlations in BOLD activity between the amygdala and ACC contrast with findings that have been cited as evidence for inhibitory control of the amygdala by the ACC. The conceptualization of post-traumatic changes in neural function should be reconsidered. 相似文献8.
Korhan Buyukturkoglu Hans Roettgers Jens Sommer Mohit Rana Leonie Dietzsch Ezgi Belkis Arikan Ralf Veit Rahim Malekshahi Tilo Kircher Niels Birbaumer Ranganatha Sitaram Sergio Ruiz 《PloS one》2015,10(8)
Introduction
Obsessive-compulsive disorder (OCD) is a common and chronic condition that can have disabling effects throughout the patient''s lifespan. Frequent symptoms among OCD patients include fear of contamination and washing compulsions. Several studies have shown a link between contamination fears, disgust over-reactivity, and insula activation in OCD. In concordance with the role of insula in disgust processing, new neural models based on neuroimaging studies suggest that abnormally high activations of insula could be implicated in OCD psychopathology, at least in the subgroup of patients with contamination fears and washing compulsions.Methods
In the current study, we used a Brain Computer Interface (BCI) based on real-time functional magnetic resonance imaging (rtfMRI) to aid OCD patients to achieve down-regulation of the Blood Oxygenation Level Dependent (BOLD) signal in anterior insula. Our first aim was to investigate whether patients with contamination obsessions and washing compulsions can learn to volitionally decrease (down-regulate) activity in the insula in the presence of disgust/anxiety provoking stimuli. Our second aim was to evaluate the effect of down-regulation on clinical, behavioural and physiological changes pertaining to OCD symptoms. Hence, several pre- and post-training measures were performed, i.e., confronting the patient with a disgust/anxiety inducing real-world object (Ecological Disgust Test), and subjective rating and physiological responses (heart rate, skin conductance level) of disgust towards provoking pictures.Results
Results of this pilot study, performed in 3 patients (2 females), show that OCD patients can gain self-control of the BOLD activity of insula, albeit to different degrees. In two patients positive changes in behaviour in the EDT were observed following the rtfMRI trainings. Behavioural changes were also confirmed by reductions in the negative valence and in the subjective perception of disgust towards symptom provoking images.Conclusion
Although preliminary, results of this study confirmed that insula down-regulation is possible in patients suffering from OCD, and that volitional decreases of insula activation could be used for symptom alleviation in this disorder. 相似文献9.
Hanani Tabana Tanya Doherty Birgitta Rubenson Debra Jackson Anna Mia Ekstr?m Anna Thorson 《PloS one》2013,8(6)
Objective
We conducted qualitative individual and combined interviews with couples to explore their experiences since the time of taking an HIV test and receiving the test result together, as part of a home-based HIV counselling and testing intervention.Methods
This study was conducted in October 2011 in rural KwaZulu-Natal, South Africa, about 2 years after couples tested and received results together. Fourteen couples were purposively sampled: discordant, concordant negative and concordant positive couples.Findings
Learning about each other’s status together challenged relationships of the couples in different ways depending on HIV status and gender. The mutual information confirmed suspected infidelity that had not been discussed before. Negative women in discordant partnerships remained with their positive partner due to social pressure and struggled to maintain their HIV negative status. Most of the couple relationships were characterized by silence and mistrust. Knowledge of sero-status also led to loss of sexual intimacy in some couples especially the discordant. For most men in concordant negative couples, knowledge of status was an awakening of the importance of fidelity and an opportunity for behaviour change, while for concordant positive and discordant couples, it was seen as proof of infidelity. Although positive HIV status was perceived as confirmation of infidelity, couples continued their relationship and offered some support for each other, living and managing life together. Sexual life in these couples was characterized by conflict and sometimes violence. In the concordant negative couples, trust was enhanced and behaviour change was promised.Conclusions
Findings suggest that testing together as couples challenged relationships in both negative and positive ways. Further, knowledge of HIV status indicated potential to influence behaviour change especially among concordant negatives. In the discordant and concordant positive couples, traditional gender roles exposed women’s vulnerability and their lack of decision-making power. 相似文献10.
Introduction
Surface electromyography (sEMG) is the measurement of the electrical activity of the skeletal muscle tissue detected at the skin’s surface. Typically, a bipolar electrode configuration is used. Most muscles have pennate and/or curved fibres, meaning it is not always feasible to align the bipolar electrodes along the fibres direction. Hence, there is a need to explore how different electrode designs can affect sEMG measurements.Method
A three layer finite element (skin, fat, muscle) muscle model was used to explore different electrode designs. The implemented model used as source signal an experimentally recorded intramuscular EMG taken from the biceps brachii muscle of one healthy male. A wavelet based intensity analysis of the simulated sEMG signal was performed to analyze the power of the signal in the time and frequency domain.Results
The model showed muscle tissue causing a bandwidth reduction (to 20-92- Hz). The inter-electrode distance (IED) and the electrode orientation relative to the fibres affected the total power but not the frequency filtering response. The effect of significant misalignment between the electrodes and the fibres (60°- 90°) could be reduced by increasing the IED (25–30 mm), which attenuates signal cancellation. When modelling pennated fibres, the muscle tissue started to act as a low pass filter. The effect of different IED seems to be enhanced in the pennated model, while the filtering response is changed considerably only when the electrodes are close to the signal termination within the model. For pennation angle greater than 20°, more than 50% of the source signal was attenuated, which can be compensated by increasing the IED to 25 mm.Conclusion
Differences in tissue filtering properties, shown in our model, indicates that different electrode designs should be considered for muscle with different geometric properties (i.e. pennated muscles). 相似文献11.
Toshihiko Takada Hiroki Nishiwaki Yosuke Yamamoto Yoshinori Noguchi Shingo Fukuma Shin Yamazaki Shunichi Fukuhara 《PloS one》2015,10(9)
Background
Digital rectal examination (DRE) has been traditionally recommended to evaluate acute appendicitis, although several reports indicate its lack of utility for this diagnosis. No meta-analysis has examined DRE for diagnosis of acute appendicitis.Objectives
To assess the role of DRE for diagnosis of acute appendicitis.Data Sources
Cochrane Library, PubMed, and SCOPUS from the earliest available date of indexing through November 23, 2014, with no language restrictions.Study Selection
Clinical studies assessing DRE as an index test for diagnosis of acute appendicitis.Data Extraction and Synthesis
Two independent reviewers extracted study data and assessed the quality, using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Bivariate random-effects models were used for the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio (DOR) as point estimates with 95% confidence intervals (CI).Main Outcomes and Measures
The main outcome measure was the diagnostic performance of DRE for diagnosis of acute appendicitis.Results
We identified 19 studies with a total of 7511 patients. The pooled sensitivity and specificity were 0.49 (95% CI 0.42–0.56) and 0.61 (95% CI 0.53–0.67), respectively. The positive and negative likelihood ratios were 1.24 (95% CI 0.97–1.58) and 0.85 (95% CI 0.70–1.02), respectively. The DOR was 1.46 (0.95–2.26).Conclusion and Relevance
Acute appendicitis cannot be ruled in or out through the result of DRE. Reconsideration is needed for the traditional teaching that rectal examination should be performed routinely in all patients with suspected appendicitis. 相似文献12.
Dong Ryul Jang Dae Chul Jung Young Taik Oh Songmi Noh Kyunghwa Han Kiwook Kim Koon-Ho Rha Young Deuk Choi Sung Joon Hong 《PloS one》2015,10(6)
Objectives
To prospectively determine whether multi-parametric MRI (mpMRI) - contrast-enhanced ultrasound (CEUS) correlated, imaging-guided target biopsy (TB) method could improve the detection of prostate cancer in re-biopsy setting of patients with prior negative biopsy.Methods
From 2012 to 2014, a total of 42 Korean men with a negative result from previous systematic biopsy (SB) and elevated prostate-specific antigen underwent 3T mpMRI and real-time CEUS guided TB. Target lesions were determined by fusion of mpMRI and CEUS. Subsequently, 12-core SB was performed by a different radiologist. We compared core-based cancer detection rates (CaDR) using the generalized linear mixed model (GLIMMIX) for each biopsy method.Results
Core-based CaDR was higher in TB (17.92%, 38 of 212 cores) than in SB (6.15%, 31 of 504 cores) (p < 0.0001; GLIMMIX). In the cancer-positive TB cores, CaDR with suspicious lesions by mpMRI was higher than that by CEUS (86.8% vs. 60.5%, p= 0.02; paired t-test) and concordant rate between mpMRI and CEUS was significantly different with discordant rate (48% vs. 52%, p=0.04; McNemar’s test).Conclusion
The mpMRI-CEUS correlated TB technique for the repeat prostate biopsy of patients with prior negative biopsy can improve CaDR based on the number of cores taken. 相似文献13.
Objective
Repetitive Transcranial Magnetic Stimulation (rTMS) is a novel therapeutic tool to induce a suppression of tinnitus. However, the optimal target sites are unknown. We aimed to determine whether low-frequency rTMS induced lasting suppression of tinnitus by decreasing neural activity in the cortex, navigated by high-density electroencephalogram (EEG) source analysis, and the utility of EEG for targeting treatment.Methods
In this controlled three-armed trial, seven normal hearing patients with tonal tinnitus received a 10-day course of 1-Hz rTMS to the cortex, navigated by high-density EEG source analysis, to the left temporoparietal cortex region, and to the left temporoparietal with sham stimulation. The Tinnitus handicap inventory (THI) and a visual analog scale (VAS) were used to assess tinnitus severity and loudness. Measurements were taken before, and immediately, 2 weeks, and 4 weeks after the end of the interventions.Results
Low-frequency rTMS decreased tinnitus significantly after active, but not sham, treatment. Responders in the EEG source analysis-based rTMS group, 71.4% (5/7) patients, experienced a significant reduction in tinnitus loudness, as evidenced by VAS scores. The target site of neuronal generators most consistently associated with a positive response was the frontal lobe in the right hemisphere, sourced using high-density EEG equipment, in the tinnitus patients. After left temporoparietal rTMS stimulation, 42.8% (3/7) patients experienced a decrease in tinnitus loudness.Conclusions
Active EEG source analysis based rTMS resulted in significant suppression in tinnitus loudness, showing the superiority of neuronavigation-guided coil positioning in dealing with tinnitus. Non-auditory areas should be considered in the pathophysiology of tinnitus. This knowledge in turn can contribute to investigate the pathophysiology of tinnitus. 相似文献14.
Jun Won Kim Bung-Nyun Kim Jaewon Lee Chul Na Baik Seok Kee Kyung Joon Min Doug Hyun Han Johanna Inhyang Kim Young Sik Lee 《PloS one》2016,11(3)
Introduction
Theta-phase gamma-amplitude coupling (TGC) measurement has recently received attention as a feasible method of assessing brain functions such as neuronal interactions. The purpose of this electroencephalographic (EEG) study is to understand the mechanisms underlying the deficits in attentional control in children with attention deficit/hyperactivity disorder (ADHD) by comparing the power spectra and TGC at rest and during a mental arithmetic task.Methods
Nineteen-channel EEGs were recorded from 97 volunteers (including 53 subjects with ADHD) from a camp for hyperactive children under two conditions (rest and task performance). The EEG power spectra and the TGC data were analyzed. Correlation analyses between the Intermediate Visual and Auditory (IVA) continuous performance test (CPT) scores and EEG parameters were performed.Results
No significant difference in the power spectra was detected between the groups at rest and during task performance. However, TGC was reduced during the arithmetic task in the ADHD group compared with the normal group (F = 16.70, p < 0.001). The TGC values positively correlated with the IVA CPT scores but negatively correlated with theta power.Conclusions
Our findings suggest that desynchronization of TGC occurred during the arithmetic task in ADHD children. TGC in ADHD children is expected to serve as a promising neurophysiological marker of network deactivation during attention-demanding tasks. 相似文献15.
16.
Tsung-Hsien Chiang Yi-Chia Lee Wan-Chung Liao Jui-Hung Chung Han-Mo Chiu Chia-Hung Tu Su-Chiu Chen Ming-Shiang Wu 《PloS one》2015,10(9)
Background
Following a negative test, the performance of fecal immunochemical testing in the subsequent screening round is rarely reported. It is crucial to allocate resources to participants who are more likely to test positive subsequently following an initial negative result.Objective
To identify risk factors associated with a positive result in subsequent screening.Methods
Dataset was composed of consecutive participants who voluntarily underwent fecal tests and colonoscopy in a routine medical examination at the National Taiwan University Hospital between January 2007 and December 2011. Risk factor assessment of positive fecal test in subsequent screening was performed by using the Cox proportional hazards models.Results
Our cohort consisted of 3783 participants during a 5-year period. In three rounds of subsequent testing, 3783, 1537, and 624 participants underwent fecal tests, respectively; 5.7%, 5.1%, and 3.9% tested positive, respectively, and the positive predictive values were 40.2%, 20.3%, and 20.8%, respectively. Age ≥60 years (adjusted hazard ratio: 1.53, 95% CI: 1.21–1.93) and male gender (1.32, 95% CI: 1.02–1.69) were risk factors; however, an interaction between age and gender was noted. Men had higher risk than women when they were <60 years of age (p = 0.002), while this difference was no longer observed when ≥60 years of age (p = 0.74). The optimal interval of screening timing for participant with baseline negative fecal test was 2 years.Conclusions
Following a negative test, older age and male gender are risk factors for a positive result in the subsequent rounds while the gender difference diminishes with age. Biennial screening is sufficient following a negative fecal test. 相似文献17.
Background
Observational studies (OS) and randomized controlled trials (RCTs) often report discordant results. In the Women’s Health Initiative Calcium and Vitamin D (WHI CaD) RCT, women were randomly assigned to CaD or placebo, but were permitted to use personal calcium and vitamin D supplements, creating a unique opportunity to compare results from randomized and observational analyses within the same study.Methods
WHI CaD was a 7-year RCT of 1g calcium/400IU vitamin D daily in 36,282 post-menopausal women. We assessed the effects of CaD on cardiovascular events, death, cancer and fracture in a randomized design- comparing CaD with placebo in 43% of women not using personal calcium or vitamin D supplements- and in a observational design- comparing women in the placebo group (44%) using personal calcium and vitamin D supplements with non-users. Incidence was assessed using Cox proportional hazards models, and results from the two study designs deemed concordant if the absolute difference in hazard ratios was ≤0.15. We also compared results from WHI CaD to those from the WHI Observational Study(WHI OS), which used similar methodology for analyses and recruited from the same population.Results
In WHI CaD, for myocardial infarction and stroke, results of unadjusted and 6/8 covariate-controlled observational analyses (age-adjusted, multivariate-adjusted, propensity-adjusted, propensity-matched) were not concordant with the randomized design results. For death, hip and total fracture, colorectal and total cancer, unadjusted and covariate-controlled observational results were concordant with randomized results. For breast cancer, unadjusted and age-adjusted observational results were concordant with randomized results, but only 1/3 other covariate-controlled observational results were concordant with randomized results. Multivariate-adjusted results from WHI OS were concordant with randomized WHI CaD results for only 4/8 endpoints.Conclusions
Results of randomized analyses in WHI CaD were concordant with observational analyses for 5/8 endpoints in WHI CaD and 4/8 endpoints in WHI OS. 相似文献18.
David Mesher Elaine Stanford Joanne White Jamie Findlow Rosalind Warrington Sukamal Das Richard Pebody Ray Borrow Kate Soldan 《PloS one》2016,11(3)
Background
Reported human papillomavirus (HPV) vaccination coverage in England is high, particularly in girls offered routine immunisation at age 12 years. Serological surveillance can be used to validate reported coverage and explore variations within it and changes in serological markers over time.Methods
Residual serum specimens collected from females aged 15–19 years in 2010–2011 were tested for anti-HPV16 and HPV18 IgG by ELISA. Based on these results, females were classified as follows: seronegative, probable natural infection, probable vaccine-induced seropositivity, or possible natural infection/possible vaccine-induced seropositivity. The proportion of females with vaccine-induced seropositivity was compared to the reported vaccination coverage.Results
Of 2146 specimens tested, 1380 (64%) were seropositive for both types HPV16 and HPV18 and 159 (7.4%) positive for only one HPV type. The IgG concentrations were far higher for those positive for both HPV types than those positive for only one HPV type. 1320 (62%) females were considered to have probable vaccine-induced seropositivity. Among vaccine-induced seropositives, antibody concentrations declined with increasing age at vaccination and increasing time since vaccination.Conclusions
The proportion of females with vaccine-induced seropositivity was closest to the reported 3-dose coverage in those offered the vaccination at younger ages, with a greater discrepancy in the older females. This suggests either some under-reporting of immunisations of older females and/or that partial vaccination (i.e. one- or two-doses) has provided high antibody responses in 13–17 year olds. 相似文献19.
Background
The fetal heart rate (FHR) is commonly monitored during labor to detect early fetal acidosis. FHR variability is traditionally investigated using Fourier transform, often with adult predefined frequency band powers and the corresponding LF/HF ratio. However, fetal conditions differ from adults and modify spectrum repartition along frequencies.Aims
This study questions the arbitrariness definition and relevance of the frequency band splitting procedure, and thus of the calculation of the underlying LF/HF ratio, as efficient tools for characterizing intrapartum FHR variability.Study Design
The last 30 minutes before delivery of the intrapartum FHR were analyzed.Subjects
Case-control study. A total of 45 singletons divided into two groups based on umbilical cord arterial pH: the Index group with pH ≤ 7.05 (n = 15) and Control group with pH > 7.05 (n = 30).Outcome Measures
Frequency band-based LF/HF ratio and Hurst parameter.Results
This study shows that the intrapartum FHR is characterized by fractal temporal dynamics and promotes the Hurst parameter as a potential marker of fetal acidosis. This parameter preserves the intuition of a power frequency balance, while avoiding the frequency band splitting procedure and thus the arbitrary choice of a frequency separating bands. The study also shows that extending the frequency range covered by the adult-based bands to higher and lower frequencies permits the Hurst parameter to achieve better performance for identifying fetal acidosis.Conclusions
The Hurst parameter provides a robust and versatile tool for quantifying FHR variability, yields better acidosis detection performance compared to the LF/HF ratio, and avoids arbitrariness in spectral band splitting and definitions. 相似文献20.
William Kilembe Kristin M. Wall Mammekwa Mokgoro Annie Mwaanga Elisabeth Dissen Miriam Kamusoko Hilda Phiri Jean Sakulanda Jonathan Davitte Tarylee Reddy Mark Brockman Thumbi Ndung’u Susan Allen 《PloS one》2015,10(4)