Clinical and neuroimaging correlates of cognition in HIV.

This study investigated whether HIV-positive participants, stable on combined antiretroviral therapy (cART), showed cognitive impairments relative to HIV-negative controls; and whether clinical and neuroimaging factors correlated with cognitive function in the HIV-positive participants. One hundred and twenty-six white men who have sex with men, of whom 78 were HIV-positive and stable on cART and 48 were HIV negative, were recruited to this cross-sectional study. The median age of HIV-positive participants in this study was 47. They underwent clinical and neuropsychological evaluation and magnetic resonance imaging of the brain, including diffusion tensor imaging (DTI). Cognitive scores for both groups were compared, and regression models were run to explore the influence of clinical, psychiatric, lifestyle, and neuroimaging variables on cognition. The prevalence of neurocognitive impairment, using the multivariate normative comparison criteria, was 28% in HIV-positive participants and 5% in HIV-negative participants. After covarying for age, years of education, and non-English speaking background, there were significant differences between the HIV group and the controls across four cognitive domains. The HIV group showed significantly higher mean diffusivity (MD) and lower fractional anisotropy (FA) than the control group on DTI. Although anxiety levels were clinically low, anxiety and DTI measures were the only variables to show significant correlations with cognitive function. In the HIV group, poorer cognitive performance was associated with higher MD and lower FA on DTI and higher (albeit clinically mild) levels of anxiety. Our findings suggest that white matter changes and subtle anxiety levels contribute independently to cognitive impairment in HIV.

Psychogenic amnesia: syndromes, outcome, and patterns of retrograde amnesia.

There are very few case series of patients with acute psychogenic memory loss (also known as dissociative/functional amnesia), and still fewer studies of outcome, or comparisons with neurological memory-disordered patients. Consequently, the literature on psychogenic amnesia is somewhat fragmented and offers little prognostic value for individual patients. In the present study, we reviewed the case records and neuropsychological findings in 53 psychogenic amnesia cases (ratio of 3:1, males:females), in comparison with 21 consecutively recruited neurological memory-disordered patients and 14 healthy control subjects. In particular, we examined the pattern of retrograde amnesia on an assessment of autobiographical memory (the Autobiographical Memory Interview). We found that our patients with psychogenic memory loss fell into four distinct groups, which we categorized as: (i) fugue state; (ii) fugue-to-focal retrograde amnesia; (iii) psychogenic focal retrograde amnesia following a minor neurological episode; and (iv) patients with gaps in their memories. While neurological cases were characterized by relevant neurological symptoms, a history of a past head injury was actually more common in our psychogenic cases (P = 0.012), perhaps reflecting a 'learning episode' predisposing to later psychological amnesia. As anticipated, loss of the sense of personal identity was confined to the psychogenic group. However, clinical depression, family/relationship problems, financial/employment problems, and failure to recognize the family were also statistically more common in that group. The pattern of autobiographical memory loss differed between the psychogenic groups: fugue cases showed a severe and uniform loss of memories for both facts and events across all time periods, whereas the two focal retrograde amnesia groups showed a 'reversed' temporal gradient with relative sparing of recent memories. After 3-6 months, the fugue patients had improved to normal scores for facts and near-normal scores for events. By contrast, the two focal retrograde amnesia groups showed less improvement and continued to show a reversed temporal gradient. In conclusion, the outcome in psychogenic amnesia, particularly those characterized by fugue, is better than generally supposed. Findings are interpreted in terms of Markowitsch's and Kopelman's models of psychogenic amnesia, and with respect to Anderson's neuroimaging findings in memory inhibition.

Slow wave and REM sleep deprivation effects on explicit and implicit memory during sleep.

OBJECTIVE: It has been debated whether different stages in the human sleep cycle preferentially mediate the consolidation of explicit and implicit memories, or whether all of the stages in succession are necessary for optimal consolidation. Here we investigated whether the selective deprivation of slow wave sleep (SWS) or rapid eye movement (REM) sleep over an entire night would have a specific effect on consolidation in explicit and implicit memory tasks. METHOD: Participants completed a set of explicit and implicit memory tasks at night, prior to sleep. They had 1 control night of undisturbed sleep and 2 experimental nights, during which either SWS or REM sleep was selectively deprived across the entire night (sleep conditions counterbalanced across participants). Polysomnography recordings quantified precisely the amount of SWS and REM sleep that occurred during each of the sleep conditions, and spindle counts were recorded. In the morning, participants completed the experimental tasks in the same sequence as the night before. RESULTS: SWS deprivation disrupted the consolidation of explicit memories for visuospatial information (ηp2 = .23), and both SWS (ηp2 = .53) and REM sleep (ηp2 = .52) deprivation adversely affected explicit verbal recall. Neither SWS nor REM sleep deprivation affected aspects of short-term or working memory, and did not affect measures of verbal implicit memory. Spindle counts did not correlate significantly with memory performance. CONCLUSIONS: These findings demonstrate the importance of measuring the sleep cycles throughout the entire night, and the contribution of both SWS and REM sleep to memory consolidation. (PsycINFO Database Record

The role of transcriptional regulation in maintaining the availability of mycobacterial adenylate cyclases.

Mycobacterium species have a complex cAMP regulatory network indicated by the high number of adenylate cyclases annotated in their genomes. However the need for a high level of redundancy in adenylate cyclase genes remains unknown. We have used semiquantitiative RT-PCR to examine the expression of eight Mycobacterium smegmatis cyclases with orthologs in the human pathogen Mycobacterium tuberculosis, where cAMP has recently been shown to be important for virulence. All eight cyclases were transcribed in all environments tested, and only four demonstrated environmental-mediated changes in transcription. M. smegmatis genes MSMEG_0545 and MSMEG_4279 were upregulated during starvation conditions while MSMEG_0545 and MSMEG_4924 were downregulated in H2O2 and MSMEG_3780 was downregulated in low pH and starvation. Promoter fusion constructs containing M. tuberculosis H37Rv promoters showed consistent regulation compared to their M. smegmatis orthologs. Overall our findings indicate that while low levels of transcriptional regulation occur, regulation at the mRNA level does not play a major role in controlling cellular cyclase availability in a given environment.

Effects of anti-lipid peroxidases on frozen-thawed boar spermatozoa.

This study evaluated the effects of anti-lipid peroxidases when supplemented to the thawing and incubation media of frozen-thawed boar spermatozoa. Semen pellets were thawed and incubated in media with 1.0 mM α-tocopherol or diethylenetriamine. After 1 h, the acrosome reaction was induced using calcium ionophore A23187, and acrosomes were evaluated using Wells--Awa staining. The number of spermatozoa with fragmented DNA was evaluated using silver staining after single-cell gel electrophoresis. Membrane lipid peroxidation was measured by the end point generation of malondialdehyde. The diethylenetriamine-supplemented media had a higher (P < 0.05) percentage of acrosome-reacted spermatozoa (84.4 ± 4.1%) compared to the control (78.3 ± 4.2%) and α-tocopherol-supplemented (78.0 ± 3.9%). The control had a higher (P < 0.05) percentage of spermatozoa with fragmented DNA (59.3 ± 4.3%) compared to the DETA (28.7 ± 4.1%) and α-tocopherol supplementation (28.0 ± 3.8%). Spermatozoa supplemented with diethylenetriamine had higher amounts (P < 0.05) of malondialdehyde generated (3.60 ± 0.05 µM/10(7) cells) compared to the α-tocopherol supplementation (0.14 ± 0.05 µM/10(7) cells) and the control (0.12 ± 0.05 µM/10(7) cells). These results indicate that supplementing with either 1.0 mM diethylenetriamine or α-tocopherol during semen thawing and incubation protects against DNA fragmentation, and diethylenetriamine increases the percent of spermatozoa capable of completing the acrosome reaction that could induce membrane lipid peroxidation.

How black African and white British women perceive depression and help-seeking: a pilot vignette study.

BACKGROUND: The detection of psychological problems of black African people has been found to be substantially lower, compared with white British and black Caribbean people. This may be due to differences in patients' perceptions of illness. Little research has been carried out on factors that may influence the help-seeking behaviour of black Africans. AIMS: To assess differences in the perceptions of depression of black African and white British women that may influence lower detection and to investigate whether there are ethnic group differences in reasons for not seeking formal help. METHODS: A short quantitative illness perception measure, the Brief Illness Perception Questionnaire (BIPQ), was used in a community survey, using a standard text vignette methodology to control for variations in previous experiences of depression. Responses from women who indicated that they would not seek formal help for depressive symptoms were qualitatively analyzed. RESULTS: Differences in perceptions of depression were found between black African (n = 73) and white British groups (n = 72) on five of the nine BIPQ dimensions. Black women were more likely to perceive depression to have less serious consequences; to be associated with fewer symptoms; to be less chronic; to be less amenable to treatment; and more frequently attributed depression to social factors. Over half the participants (n = 74) said they would not seek formal help for depressive symptoms. Six qualitative response categories emerged to explain non-consultation. The most common factor for both groups related to GP consultation difficulties. Significantly more white women cited preferring alternative help sources as a reason for non-consultation. The greater number of black women citing anti-medication beliefs was marginally significant. There were no differences between the ethnic groups in their use of the remaining three categories: illness characteristics; service constraints; and stigma/shame. CONCLUSION: Differing perceptions of depression among black and white women could help explain GPs' lower detection rates of depressive problems of black women. Differences in views about the formal help available may explain ethnic differences in help-seeking.

Are attractive facial characteristics peculiar to the sex of a face?

Preferences for faces are thought to be the result of either general adaptations for mate selection, and thus influenced by sexual dimorphism, or mechanisms of general information processing and thus nonspecific to faces. If mate choice determines face preference then it should follow that the sex of a face should affect attractiveness judgements. To test this idea we used image morphing to generate three versions of face images: original, opposite sex, and antiface. First we established that the sex of the face was identifiable in our images. We then collected attractiveness ratings for the three face types. We found that attractiveness ratings to the original faces were correlated with, and did not differ significantly between, ratings to the opposite-sex faces. However, ratings for either the original or opposite face types were not correlated with and were significantly lower than ratings to the antifaces. Our findings failed to support the idea that attractiveness is related to sexual dimorphism in faces alone but suggest instead that other more generic factors influence preferences for all faces.

Are representations of unfamiliar faces independent of encoding modality?

It is well documented that both featural and configural information are important in visual face recognition. Less is known, however, about the nature of the information underlying haptic face recognition and whether or not this information is the same as in vision. In our experiments we found better within modal than crossmodal face recognition performance suggesting that face representations are largely specific to each modality. Moreover, this cost in crossmodal performance was found to be independent of differences in exploratory procedures across the modalities during encoding. We found that crossmodal face perception was most efficient when configural information of the facial features was preserved suggesting that configural information is shared across modalities. Our findings suggest that face information is processed in a similar manner across vision and touch but that qualitative differences in the nature of the information encoded underlies efficient within modal relative to crossmodal recognition.

The role of long-term and short-term familiarity in visual and haptic face recognition.

Recent studies have suggested that the familiarity of a face leads to more robust recognition, at least within the visual domain. The aim of our study was to investigate whether face familiarity resulted in a representation of faces that was easily shared across the sensory modalities. In Experiment 1, we tested whether haptic recognition of a highly familiar face (one's own face) was as efficient as visual recognition. Our observers were unable to recognise their own face models from tactile memory alone but were able to recognise their faces visually. However, haptic recognition improved when participants were primed by their own live face. In Experiment 2, we found that short-term familiarisation with a set of previously unfamiliar face stimuli improved crossmodal recognition relative to the recognition of unfamiliar faces. Our findings suggest that familiarisation provides a strong representation of faces but that the nature of the information encoded during learning is critical for efficient crossmodal recognition.