Similar Patterns Of Results Research Articles

Effects of aging on task- and stimulus-related cerebral attention networks

Interactions between a dorsal attention network (DAN) and a ventral attention cerebral network (VAN) have been reported in young participants during attention or short-term memory (STM) tasks. Because it remains an underinvestigated question, age effects on DAN and VAN activity and their functional balance were explored during performance of an STM task. Older and younger groups showed similar behavioral patterns of results. At the cerebral level, DAN activation increased as a function of increasing STM load in both groups, suggesting preserved activity in DAN during healthy aging. Age-related over-recruitment in regions of the DAN in the higher task load raised the question of compensation attempt versus less efficient use of neural resources in older adults. Lesser decrease of VAN activation with increasing load and decreased stimulus-driven activation in the VAN, especially in the higher load, in older participants suggested age-related reduced response in the VAN. However, functional connectivity measures showed that VAN was still functionally connected to the DAN in older participants.

Initial Results from the Survey of Organizational Research Climates (SOuRCe) in the U.S. Department of Veterans Affairs Healthcare System.

BackgroundIn service to its core mission of improving the health and well-being of veterans, Veterans Affairs (VA) leadership is committed to supporting research best practices in the VA. Recognizing that the behavior of researchers is influenced by the organizational climates in which they work, efforts to assess the integrity of research climates and share such information with research leadership in VA may be one way to support research best practices. The Survey of Organizational Research Climate (SOuRCe) is the first validated survey instrument specifically designed to assess the organizational climate of research integrity in academic research organizations. The current study reports on an initiative to use the SOuRCe in VA facilities to characterize the organizational research climates and pilot test the effectiveness of using SOuRCe data as a reporting and feedback intervention tool.MethodsWe administered the SOuRCe using a cross-sectional, online survey, with mailed follow-up to non-responders, of research-engaged employees in the research services of a random selection of 42 VA facilities (e.g., Hospitals/Stations) believed to employ 20 or more research staff. We attained a 51% participation rate, yielding more than 5,200 usable surveys.ResultsWe found a general consistency in organizational research climates across a variety of sub-groups in this random sample of research services in the VA. We also observed similar SOuRCe scale score means, relative rankings of these scales and their internal reliability, in this VA-based sample as we have previously documented in more traditional academic research settings. Results also showed more substantial variability in research climate scores within than between facilities in the VA research service as reflected in meaningful subgroup differences. These findings suggest that the SOuRCe is suitable as an instrument for assessing the research integrity climates in VA and that the tool has similar patterns of results that have been observed in more traditional academic research settings.ConclusionsThe local and specific nature of organizational climates in VA research services, as reflected in variability across sub-groups within individual facilities, has important policy implications. Global, “one-size-fits-all” type initiatives are not likely to yield as much benefit as efforts targeted to specific organizational units or sub-groups and tailored to the specific strengths and weaknesses documented in those locations.

Associations between coping strategies and mental health in individuals with type 2 diabetes: Prospective analyses.

Individuals with type 2 diabetes are at greater risk of developing a number of mental health conditions, including depression, anxiety, and diabetes-related distress, than individuals without type 2 diabetes. Cross-sectional studies suggest that some coping strategies may increase the risk of mental health conditions in individuals with diabetes, whereas others may be protective. This study extends the cross-sectional evidence base with a prospective study. Data were collected annually for 2 years from a community sample of 1,742 adults with type 2 diabetes. Coping strategies were measured at baseline and mental health conditions were assessed at each time point with self-report symptom measures. For comparison, cross-sectional and prospective analyses were conducted. Cross-sectional analyses demonstrated that task-oriented coping was negatively associated with the likelihood of each of the mental health conditions, emotion-oriented coping was positively associated with the likelihood of each condition, and avoidance-oriented coping showed no association. Prospective analyses revealed that among individuals who did not have elevated depressive symptoms at baseline, only emotion-oriented coping predicted the likelihood of developing major depression syndrome during follow-up. Similar patterns of results were observed for elevated anxiety symptoms and diabetes-related distress. Cross-sectional results differed from prospective results. Only emotion-oriented coping appears to play a role in the development of depressive symptoms, anxiety symptoms, and diabetes-related distress. Results underscore the importance of examining prospective associations and suggest that interventions targeting specific coping strategies might alleviate mental health problems in individuals with type 2 diabetes.

Lifetime cost effectiveness of different brands of prosthesis used for total hip arthroplasty: a study using the NJR dataset.

There is little evidence on the cost effectiveness of different brands of hip prostheses. We compared lifetime cost effectiveness of frequently used brands within types of prosthesis including cemented (Exeter V40 Contemporary, Exeter V40 Duration and Exeter V40 Elite Plus Ogee), cementless (Corail Pinnacle, Accolade Trident, and Taperloc Exceed) and hybrid (Exeter V40 Trilogy, Exeter V40 Trident, and CPT Trilogy). We used data from three linked English national databases to estimate the lifetime risk of revision, quality-adjusted life years (QALYs) and cost. For women with osteoarthritis aged 70 years, the Exeter V40 Elite Plus Ogee had the lowest risk of revision (5.9% revision risk, 9.0 QALYs) and the CPT Trilogy had the highest QALYs (10.9% revision risk, 9.3 QALYs). Compared with the Corail Pinnacle (9.3% revision risk, 9.22 QALYs), the most commonly used brand, and assuming a willingness-to-pay of £20,000 per QALY gain, the CPT Trilogy is most cost effective, with an incremental net monetary benefit of £876. Differences in cost effectiveness between the hybrid CPT Trilogy and Exeter V40 Trident and the cementless Corail Pinnacle and Taperloc Exceed were small, and a cautious interpretation is required, given the limitations of the available information. However, it is unlikely that cemented brands are among the most cost effective. Similar patterns of results were observed for men and other ages. The gain in quality of life after total hip arthroplasty, rather than the risk of revision, was the main driver of cost effectiveness. Cite this article: Bone Joint J 2015;97-B:762-70.

Examining Associations Among ADHD, Homework Behavior, and Reading Comprehension

Previous literature has indicated an important association between reading comprehension and both attention-deficit/hyperactivity disorder (ADHD) and homework habits. This investigation sought to extend previous knowledge by providing information about how ADHD and homework behavior (i.e., completing homework regularly) may jointly influence reading comprehension. Using a genetically sensitive design, this study examined the genetic and environmental influences on and between ADHD, homework behavior and reading comprehension. Participants for this study included 691 twin pairs (351 monozygotic, 340 same-sex dizygotic) from the Florida Twin Project on Behavior and Environment (FTP-BE) and 2647 twin pairs (865 monozygotic, 1782 dizygotic) from the larger Florida Twin Project on Reading (FTP-R) in Grades 3 through 7. Three separate models, each representing a different definition of ADHD (full ADHD, inattention only, and hyperactivity/impulsivity only), showed similar patterns of results; therefore, results of the full ADHD model are discussed. Overlapping genetic influences were found between ADHD, homework behavior, and reading comprehension, but no shared environmental influences among all three. However, shared environmental influences overlapped between homework behavior and reading comprehension. Although the sources of this environmental overlap are unknown, these results have implications for improving homework practices and their subsequent influence on literacy skills through homework environments.

Comparison of different spatial transformations applied to EEG data: A case study of error processing

The purpose of this paper is to compare the effects of different spatial transformations applied to the same scalp-recorded EEG data. The spatial transformations applied are two referencing schemes (average and linked earlobes), the surface Laplacian, and beamforming (a distributed source localization procedure). EEG data were collected during a speeded reaction time task that provided a comparison of activity between error vs. correct responses. Analyses focused on time–frequency power, frequency band-specific inter-electrode connectivity, and within-subject cross-trial correlations between EEG activity and reaction time. Time–frequency power analyses showed similar patterns of midfrontal delta–theta power for errors compared to correct responses across all spatial transformations. Beamforming additionally revealed error-related anterior and lateral prefrontal beta-band activity. Within-subject brain–behavior correlations showed similar patterns of results across the spatial transformations, with the correlations being the weakest after beamforming. The most striking difference among the spatial transformations was seen in connectivity analyses: linked earlobe reference produced weak inter-site connectivity that was attributable to volume conduction (zero phase lag), while the average reference and Laplacian produced more interpretable connectivity results. Beamforming did not reveal any significant condition modulations of connectivity. Overall, these analyses show that some findings are robust to spatial transformations, while other findings, particularly those involving cross-trial analyses or connectivity, are more sensitive and may depend on the use of appropriate spatial transformations.

Maternal adiposity and blood pressure in pregnancy

Greater maternal adiposity is a potentially modifiable risk factor for elevated blood pressure during pregnancy; however, the association has been little studied in Asian populations, and no study has evaluated potential differences in the adiposity-blood pressure relation between ethnic groups or interaction with gestational diabetes. We performed a cross-sectional evaluation of a Singapore mother-offspring cohort comprising 799 pregnant Chinese, Malay and Indian women. Data on body weight, height, skinfold thickness and glycaemia (oral glucose tolerance test) were collected during the 2nd trimester; peripheral SBP and DBP were measured using an oscillometric device and central pressures by noninvasive radial applanation tonometry. The associations between adiposity measures BMI and sum of skinfold thickness and blood pressure outcomes were examined by linear regression with adjustment for potential confounders. Higher maternal BMI was associated with elevated peripheral and central pressures: the increases in pressure (mmHg) for each kg/m(2) increase in BMI were 1.19 (95% confidence interval, 1.03-1.36) for peripheral SBP, 0.76 (0.63-0.89) for peripheral DBP, 1.02 (0.87-1.17) for central systolic pressure and 0.26 (0.16-0.37) for central pulse pressure. The associations were generally stronger in Chinese women (P-interaction = 0.03 for central pulse pressure) and individuals with gestational diabetes (P-interaction = 0.03 for DBP and P-interaction = 0.046 for central systolic pressure). Similar patterns of results were found when using skinfold thickness as the measure of adiposity. Maternal adiposity is associated with higher peripheral and central blood pressures during pregnancy. Stronger associations in Chinese women and individuals with gestational diabetes warrant further investigation.

Immigrant influx and social cohesion erosion

Abstract If immigration causes a decrease in social cohesion, then it may also be an important contributing factor in the recent failure of financial institutions. The present analysis finds some evidence for a negative relationship between immigration and volunteering from the Current Population Survey 2004–2008 September Supplements. Various specifications confirm the tendency of immigrant inflows to decrease social cohesion, as measured by the tendency of native U.S. citizens to volunteer. Differences in effect by type of volunteering organization, country of origin of immigrants, functional form, and voting as the relevant measure of social cohesion are explored with similar patterns of results. Differences in effect by city size provide a counterpoint, lending support to the alternative idea that immigration does not in fact decrease social cohesion. JEL codes H8; Z13; J61

Very Similar Spacing-Effect Patterns in Very Different Learning/Practice Domains

Temporally distributed (“spaced”) learning can be twice as efficient as massed learning. This “spacing effect” occurs with a broad spectrum of learning materials, with humans of different ages, with non-human vertebrates and also invertebrates. This indicates, that very basic learning mechanisms are at work (“generality”). Although most studies so far focused on very narrow spacing interval ranges, there is some evidence for a non-monotonic behavior of this “spacing effect” (“nonlinearity”) with optimal spacing intervals at different time scales. In the current study we focused both the nonlinearity aspect by using a broad range of spacing intervals and the generality aspect by using very different learning/practice domains: Participants learned German-Japanese word pairs and performed visual acuity tests. For each of six groups we used a different spacing interval between learning/practice units from 7 min to 24 h in logarithmic steps. Memory retention was studied in three consecutive final tests, one, seven and 28 days after the final learning unit. For both the vocabulary learning and visual acuity performance we found a highly significant effect of the factor spacing interval on the final test performance. In the 12 h-spacing-group about 85% of the learned words stayed in memory and nearly all of the visual acuity gain was preserved. In the 24 h-spacing-group, in contrast, only about 33% of the learned words were retained and the visual acuity gain dropped to zero. The very similar patterns of results from the two very different learning/practice domains point to similar underlying mechanisms. Further, our results indicate spacing in the range of 12 hours as optimal. A second peak may be around a spacing interval of 20 min but here the data are less clear. We discuss relations between our results and basic learning at the neuronal level.

Validation of the Integration of Stressful Life Experiences Scale–Short Form in a Bereaved Sample

The Integration of Stressful Life Experiences Scale (ISLES) is an assessment of meaning made of stress that has been used successfully with bereaved individuals and other vulnerable populations. Drawing upon information from 741 bereaved respondents, the present study tests the validity of the ISLES–Short Form (ISLES-SF), which is a 6-item version of the original 16-item measure. Tests of concurrent and incremental validity yielded highly similar patterns of results for the full ISLES and ISLES-SF, supporting the use of this briefer version of the scale. Results also highlighted the unique association (controlling for demographics, circumstances of the death, and prolonged grief symptoms) between greater meaning made of loss and higher levels of mental and physical health. These findings add to a growing body of literature that supports theoretical models that view meaning-making as a crucial determinant of adjustment to loss among many grievers.

The Role of Perceived Voice and Speech Characteristics in Vocal Emotion Communication

Aiming at a more comprehensive assessment of nonverbal vocal emotion communication, this article presents the development and validation of a new rating instrument for the assessment of perceived voice and speech features. In two studies, using two different sets of emotion portrayals by German and French actors, ratings of perceived voice and speech characteristics (loudness, pitch, intonation, sharpness, articulation, roughness, instability, and speech rate) were obtained from non-expert (untrained) listeners. In addition, standard acoustic parameters were extracted from the voice samples. Overall, highly similar patterns of results were found in both studies. Rater agreement (reliability) reached highly satisfactory levels for most features. Multiple discriminant analysis results reveal that both perceived vocal features and acoustic parameters allow a high degree of differentiation of the actor-portrayed emotions. Positive emotions can be classified with a higher hit rate on the basis of perceived vocal features, confirming suggestions in the literature that it is difficult to find acoustic valence indicators. The results show that the suggested scales (Geneva Voice Perception Scales) can be reliably measured and make a substantial contribution to a more comprehensive assessment of the process of emotion inferences from vocal expression.

“Every Shut Eye, Ain’t Sleep”: The Role of Racism-Related Vigilance in Racial/Ethnic Disparities in Sleep Difficulty

Although racial/ethnic disparities in health have been well-characterized in biomedical, public health, and social science research, the determinants of these disparities are still not well-understood. Chronic psychosocial stress related specifically to the American experience of institutional and interpersonal racial discrimination may be an important determinant of these disparities, as a growing literature in separate scientific disciplines documents the adverse health effects of stress and the greater levels of stress experienced by non-White compared to White Americans. However, the empirical literature on the importance of stress for health and health disparities specifically due to racial discrimination, using population-representative data, is still small and mixed. In this paper, we explore the association between a novel measure of racially-salient chronic stress - "racism-related vigilance" - and sleep difficulty. We found that, compared to the White adults in our sample, Black (but not Hispanic) adults reported greater levels of vigilance. This vigilance was positively associated with sleep difficulty to similar degrees for all racial/ethnic groups in our sample (White, Black, Hispanic). Black adults reported greater levels of sleep difficulty compared to White adults. This disparity was slightly attenuated after adjustment for education and income. However, this disparity was completely attenuated after adjustment for racism-related vigilance. We found similar patterns of results for Hispanic compared to White adults, however, the disparities in sleep difficulty were smaller and not statistically significant. Because of the importance of sleep quality to health, our results suggest that the anticipation of and perseveration about racial discrimination is an important determinant of racial disparities in health.

Mild Depressive Symptoms Are Associated with Elevated C-Reactive Protein and Proinflammatory Cytokine Levels During Early to Midgestation: A Prospective Pilot Study

We examined depressive symptoms, C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels during early to-midgestation. We measured depressive symptoms on the Patient Health Questionnaire-9 (PHQ-9), and serum CRP, IL-6, and TNF-α levels twice in 27 pregnant women. After adjustment, depressive symptoms prospectively (β=0.42, p<0.05 at 16-20 weeks of gestation) and concurrently (β=0.54, p<0.01 at 7-10 weeks of gestation) predicted elevated CRP [F (2, 14)=9.20, p=0.003, R(2)=0.57 and F (3, 15)=9.08, p=0.001, R(2)=0.64, respectively]. There were similar patterns of results for TNF-α (β=0.72, p<0.01) and IL-6 levels (β=0.39, p<0.05) at 7-10 weeks of gestation [F (2,19)=8.84, p=0.002, R(2)=0.48]. Furthermore, the association between depressive symptoms at 7-10 weeks of gestation and increased IL-6 levels at 16-20 weeks of gestation approached statistical significance. We confirmed the findings with the Wilcoxon signed rank test (IL-6: Z=2.44, p=0.015; TNF-α: Z=1.94, p=0.05; CRP: approached statistical significance). These pilot data suggest that depressive symptoms may be associated with inflammatory markers during early to-midgestation.

Dissociation of formal and temporal predictability in early auditory evoked potentials

Perceived regularity among events in the environment allows predictions regarding the “when” and the “what” dimensions of future events. In this context, one crucial question concerns the impact and the potentially optimizing effect, of regular temporal structure on the processing of “what”, or formal, information. The current study addresses this issue by investigating whether temporal and formal structure interact during early stages of sensory processing, and by relating the respective findings to the concept of a predictive bias in brain function. Analyses were performed on two components of the auditory event-related-potential of the electroencephalogram, namely the P50 and the N100. Oddball sequences consisting of frequent standard and infrequent deviant sinusoidal tones were presented with either regular or irregular temporal structure in pre-attentive and attentive experimental settings (Schwartze, Rothermich, Schmidt-Kassow, & Kotz, 2011). Temporal regularity effects on pre-attentive and attentive processing of deviance. Biological Psychology, 87, 146–151). The results confirm that the P50 and the N100 amplitudes reliably encode formal and temporal predictability. Similar patterns of results obtained with pre-attentive and attentive task instructions, as well as the absence of a significant interaction of formal and temporal structure suggest that the P50 response may be interpreted as an automatic marker of predictability, whereas the N100 may represent a more complex marker, in which formal and temporal structure start interacting as a function of attention.

Estimating the subjective value of future rewards: comparison of adjusting-amount and adjusting-delay procedures.

The present study examined whether equivalent discounting of delayed rewards is observed with different experimental procedures. If the underlying decision-making process is the same, then similar patterns of results should be observed regardless of procedure, and similar estimates of the subjective value of future rewards (i.e., indifference points) should be obtained. Two experiments compared discounting on three types of procedure: adjusting-delay (AD), adjusting-immediate-amount (AIA), and adjusting-delayed-amount (ADA). For the two procedures for which discounting functions can be established (i.e., AD and AIA), a hyperboloid provided good fits to the data at both the group and individual levels, and individuals' discounting on one procedure tended to be correlated with their discounting on the other. Notably, the AIA procedure produced the more consistent estimates of the degree of discounting, and in particular, discounting on the AIA procedure was unaffected by the order in which choices were presented. Regardless of which of the three procedures was used, however, similar patterns of results were obtained: Participants systematically discounted the value of delayed rewards, and robust magnitude effects were observed. Although each procedure may have its own advantages and disadvantages, use of all three types of procedure in the present study provided converging evidence for common decision-making processes underlying the discounting of delayed rewards.

Attentional Capture without Awareness in Complex Visual Tasks

Abrupt onsets of visual cues capture an observer's attention, even when the cues do not reach the observer's visual awareness. In the present study, we investigated the effects of subthreshold cues on the performance of a useful field of view task. Participants localized a target stimulus presented in the peripheral visual field while identifying a character presented at the fovea. Before the presentation of central and peripheral targets, a suprathreshold or subthreshold cue indicating a likely location of the peripheral target was presented. We found that the suprathreshold cue led to both a benefit in the valid trials and cost in the invalid trials, while the subthreshold cue produced only a benefit in the valid trials without a cost in the invalid trials. Similar patterns of results were also observed when the cue preceded the targets by 10-200 ms, although a small cost was observed for the 12 deg eccentricity at the stimulus onset asynchronies of 50 ms and 100 ms in the subthreshold condition. These results indicate that attentional capture occurs without awareness of the cue and suggest that the effect of the cue on the spatial shift of attention would be different between the suprathreshold and subthreshold conditions.

Auditory Emotion Recognition Impairments in Schizophrenia: Relationship to Acoustic Features and Cognition

Schizophrenia is associated with deficits in the ability to perceive emotion based on tone of voice. The basis for this deficit remains unclear, however, and relevant assessment batteries remain limited. The authors evaluated performance in schizophrenia on a novel voice emotion recognition battery with well-characterized physical features, relative to impairments in more general emotional and cognitive functioning. The authors studied a primary sample of 92 patients and 73 comparison subjects. Stimuli were characterized according to both intended emotion and acoustic features (e.g., pitch, intensity) that contributed to the emotional percept. Parallel measures of visual emotion recognition, pitch perception, general cognition, and overall outcome were obtained. More limited measures were obtained in an independent replication sample of 36 patients, 31 age-matched comparison subjects, and 188 general comparison subjects. Patients showed statistically significant large-effect-size deficits in voice emotion recognition (d=1.1) and were preferentially impaired in recognition of emotion based on pitch features but not intensity features. Emotion recognition deficits were significantly correlated with pitch perception impairments both across (r=0.56) and within (r=0.47) groups. Path analysis showed both sensory-specific and general cognitive contributions to auditory emotion recognition deficits in schizophrenia. Similar patterns of results were observed in the replication sample. The results demonstrate that patients with schizophrenia show a significant deficit in the ability to recognize emotion based on tone of voice and that this deficit is related to impairment in detecting the underlying acoustic features, such as change in pitch, required for auditory emotion recognition. This study provides tools for, and highlights the need for, greater attention to physical features of stimuli used in studying social cognition in neuropsychiatric disorders.

Neuronal Responses to Texture-Defined Form in Macaque Visual Area V2

Human and macaque observers can detect and discriminate visual forms defined by differences in texture. The neurophysiological correlates of visual texture perception are not well understood and have not been studied extensively at the single-neuron level in the primate brain. We used a novel family of texture patterns to measure the selectivity of neurons in extrastriate cortical area V2 of the macaque (Macaca nemestrina, Macaca fascicularis) for the orientation of texture-defined form, and to distinguish responses to luminance- and texture-defined form. Most V2 cells were selective for the orientation of luminance-defined form; they signaled the orientation of the component gratings that made up the texture patterns but not the overall pattern orientation. In some cells, these luminance responses were modulated by the direction or orientation of the texture envelope, suggesting an interaction of luminance and texture signals. We found little evidence for a "cue-invariant" representation in monkey V2. Few cells showed selectivity for the orientation of texture-defined form; they signaled the orientation of the texture patterns and not that of the component gratings. Small datasets recorded in monkey V1 and cat area 18 showed qualitatively similar patterns of results. Consistent with human functional imaging studies, our findings suggest that signals related to texture-defined form in primate cortex are most salient in areas downstream of V2. V2 may still provide the foundation for texture perception, through the interaction of luminance- and texture-based signals.

Influence of bacteria and protozoa from the rumen of buffalo on in-vitro activities of anaerobic fungus Caecomyces sp. isolated from the feces of elephant

Anaerobic fungal isolates Caecomyces sp. from the feces of elephant andOrpinomyces sp. from buffalo rumen were co-cultured in-vitro with rumen bacterial and protozoal fractions collected from buffalo to observe the possible fate of these fungi in the rumen, if inoculated as microbial-feed supplements. When co-cultured together or separately with rumen bacteria and protozoa, Caecomycessp. was adversely affected. However, bacterial and protozoal counts were higher, compared to the counts when grown alone. Similar patterns of results were observed when Orpinomyces sp. was grown in co-culture with bacteria and protozoa separately as well as together, indicating that it is possibly the inhibitory action of bacteria and protozoa, and not inter-species competition, that affects the growth of fungi preventing them from attaining their full fibre-degrading potential. Conversely, although fungal counts were lowered during their co-culturing with bacterial and protozoal fractions, their co-culturing increased the FPase activity of the co-cultured fraction which could be the apparent reason for enhanced fibre degradation. Key words: Rumen microflora, anaerobic fungi, microbial interactions, fibre degradation.

Expression of Nef from unintegrated HIV-1 DNA downregulates cell surface CXCR4 and CCR5 on T-lymphocytes

BackgroundTranscription of HIV-1 cDNA prior to, or in the absence of, integration leads to synthesis of all classes of viral RNA transcripts. Yet only a limited range of viral proteins, including Nef, are translated in this context. Nef expression from unintegrated HIV-1 DNA has been shown to reduce cell surface CD4 levels in T-cells. We wished to determine whether Nef expressed from unintegrated DNA was also able to downregulate the chemokine coreceptors CXCR4 and CCR5.Viral integration was blocked through use of an inactive integrase or by using the integrase inhibitor raltegravir. Infected cells bearing unintegrated DNA were assayed by flow cytometry in the GFP reporter cell line, Rev-CEM, for cell surface levels of CD4, CXCR4 and CCR5.ResultsIn cells bearing only unintegrated HIV-1 DNA, we found that surface levels of CXCR4 were significantly reduced, while levels of CCR5 were also diminished, but not to the extent of CXCR4. We also confirmed the downregulation of CD4. Similar patterns of results were obtained with both integrase-deficient virus or with wild-type infections of cells treated with raltegravir. The Alu-HIV qPCR assay that we used for detection of proviral DNA did not detect any integrated viral DNA.ConclusionsOur results demonstrate that Nef can be expressed from unintegrated DNA at functionally relevant levels and suggest a role for Nef in downregulation of CXCR4 and CCR5. These findings may help to explain how downregulation of CXCR4, CCR5 and CD4 might restrict superinfection and/or prevent signal transduction involving HIV-1 infected cells.