Somatic mutation rates scale with lifespan across mammals

The rates and patterns of somatic mutation in normal tissues are largely unknown outside of humans1-7. Comparative analyses can shed light on the diversity of mutagenesis across species, and on long-standing hypotheses about the evolution of somatic mutation rates and their role in cancer and ageing. Here we performed whole-genome sequencing of 208 intestinal crypts from 56 individuals to study the landscape of somatic mutation across 16 mammalian species. We found that somatic mutagenesis was dominated by seemingly endogenous mutational processes in all species, including 5-methylcytosine deamination and oxidative damage. With some differences, mutational signatures in other species resembled those described in humans8, although the relative contribution of each signature varied across species. Notably, the somatic mutation rate per year varied greatly across species and exhibited a strong inverse relationship with species lifespan, with no other life-history trait studied showing a comparable association. Despite widely different life histories among the species we examined-including variation of around 30-fold in lifespan and around 40,000-fold in body mass-the somatic mutation burden at the end of lifespan varied only by a factor of around 3. These data unveil common mutational processes across mammals, and suggest that somatic mutation rates are evolutionarily constrained and may be a contributing factor in ageing.

At greatest risk: pre- and early adolescent Bahamian youth experiencing anal intercourse

Although anal intercourse carries great risk for HIV transmission, little research has focused on it among the general population, particularly pre- and early adolescents. This study describes the prevalence of anal and vaginal intercourse among Bahamian pre- and early adolescents and associations with other risk behaviours, family interactions and intrapersonal correlates. Data were from 1274 sixth-grade students aged 9–14 years who completed self-administered questionnaires at baseline of a larger school-based behavioural intervention study. Youth who reported having had anal intercourse engaged in significantly higher rates of several risk behaviours and were significantly more likely to engage in risk behaviours over the next six months, compared with youth with a history of vaginal intercourse only, who in turn were more likely than virgin adolescents. Youth indulging in anal intercourse also perceived significantly lower levels of parental monitoring. Multivariate analyses revealed that anal intercourse, vaginal intercourse, reduced parental monitoring, depression and perceived friend high-risk involvement were associated with both past involvement and future intention to engage in other risk behaviours. Anal intercourse poses a direct threat to the health of these children and is a flag for a constellation of other risks.

Evaluation of a group programme of mindfulness-based cognitive therapy for women with fertility problems

Mindfulness-based cognitive therapy (MBCT) has proved helpful for a number of health-related conditions but there is relatively little published literature about its use with fertility problems. The aim of this paper is to describe a pilot group programme adopted by a Clinical Health Psychology department, and to present findings from the routine outcomes data gathered by the service, evaluating its effectiveness. Data from nine women with fertility problems that took part in the programme were analysed. They completed measures of wellbeing and psychological distress before and after the treatment. The results showed clinically significant improvements in participants' wellbeing scores and psychological distress. It was a limitation of the study that the impact of concurrent treatments could not be assessed and so could also have contributed to this outcome in half of the cases. Nevertheless, these results suggest that MBCT may be a helpful treatment for women presenting with fertility-related distress.

Effects on condom use of an HIV prevention programme 36 months postintervention: a cluster randomized controlled trial among Bahamian youth

Data are lacking on long-term effects of HIV behavioural intervention programmes. In this study, we report intervention effects 36 months postintervention on condom use and relevant outcome variables from the theory-based programme 'Focus on Youth in the Caribbean' (FOYC). Participants (1360 sixth-grade youth) were randomized by school into: (1) FOYC, plus one of two brief parent interventions or (2) the control condition 'Wondrous Wetlands', plus a brief parent intervention. Mixed effect analysis demonstrated significant programme effects, including enhanced HIV/AIDS knowledge (effect size D = 0.44, 95% confidence interval [CI]: 0.43, 0.46), increased self-efficacy of (D = 0.42, 95% CI: 0.30, 0.54), skills for (D = 0.62, 95% CI: 0.56, 0.64) and intention to use a condom (D = 0.20, 95% CI: 0.03, 0.37). Youth who received FOYC plus the parental monitoring intervention had higher condom use rates (odds ratio = 1.49, 95% CI: 0.97, 2.28). Feedback effects from key variables were also detected, supporting the sustained effect.

Condom-use skills checklist: a proxy for assessing condom-use knowledge and skills when direct observation is not possible

Because of the continued importance of correct condom-use in controlling the HIV epidemic and the limited availability of tools for assessing correct condom-use, methods for assessing condom-application skills, especially when direct observation is not feasible, are needed. Accordingly, in the context of a high-risk population (The Bahamas) for HIV, a 17-item scale--the Condom-use Skills Checklist (CUSC)--was developed for use among young adolescents and adults. The rationale and approach to developing the scale and some measures of internal consistency, construct validity, and criterion-related validity have been described. It is concluded that the scale offers a reasonable alternative to direct observation among older subjects and that further development may make it more useful among pre-adolescents.

Psychosocial aspects of human immunodeficiency virus (HIV) infection in a pre-HAART sample

The psychosocial consequences of HLV-infection were studied using a semi-structured interview and the psychiatric questionnaire SCL-90-R, in 3 matched groups of homosexual men: 20 patients with Aids, 20 asymptomatic HIV-infected and 20 non-infected controls. The data was collected before the HAART (Highly Active Anti-retroviral Therapy) era. The results showed that the infected subjects more often concealed their homosexuality, engaged in more risky sexual behavior and were less inclined to regard AIDS as a serious problem. The infected subjects also revealed more psychopathology on 5 of the 9 indexes on the SCL-90. Across all 3 groups, contact ability was correlated to being open about homosexuality and to psychological well-being. These results indicate that HIV has considerable impact on psychological well-being among the infected and point to the need for health-care workers to be especially attentive to those HIV-infected who have difficulty in talking to others about their situation.

Comparison of microembolism detected by transcranial Doppler and neuropsychological sequelae of carotid surgery and percutaneous transluminal angioplasty

BACKGROUND AND PURPOSE

Percutaneous transluminal angioplasty (PTA) is currently being assessed for the treatment of carotid stenosis. In comparison with carotid endarterectomy (CEA), there is evidence of an increased risk of cerebral microembolism during the procedure. We have sought evidence of any neuropsychological sequelae of carotid PTA and compared it with CEA to demonstrate the relative safety of the 2 treatment options.

METHODS

The neuropsychological outcomes after CEA and PTA were compared in 2 matched groups of patients with severe symptomatic carotid stenosis, 96% of whom had been randomized in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), at a single center. Transcranial Doppler insonation of the middle cerebral artery was used to measure cerebral reactivity in response to carbon dioxide inhalation before treatment and then to detect microembolization of the ipsilateral cerebral hemisphere and measure changes in blood flow velocity during the procedures. The performance on a neuropsychological test battery administered before, 6 weeks after, and 6 months after the procedure was compared in 20 patients undergoing PTA and 26 having CEA.

RESULTS

At 6 weeks, 5 patients in each group showed a similar decline in neuropsychological performance; global measures showed no significant difference between the 2 procedures, despite a significantly higher incidence of microemboli during PTA. Both groups showed a marked reduction in anxiety after treatment.

CONCLUSIONS

The findings provide some reassurance that PTA is not associated with greater cerebral complications than CEA, despite the higher embolic load recorded by transcranial Doppler ultrasonography during angioplasty.

Impact of Carotid Endarterectomy upon Cognitive Functioning

BACKGROUND AND PURPOSE

The extent to which carotid endarterectomy (CEA) influences cognitive functioning has been the subject of a number of studies often with conflicting conclusions. This paper systematically reviews the literature in an attempt to clarify this issue.

RESULTS

Although the majority of studies (16/28) reported an improvement in cognition after surgery, a substantial minority (12/28) found no change. Studies before 1984 tended to report an improvement, while later studies tended to report no change in cognition. Cognitive improvement was also more likely the longer the time interval between CEA and assessment. The studies were found to differ on many methodological factors, e.g. sample size, type of patient and control group, severity and side of carotid stenosis, the range of cognitive tests and timing of postoperative assessment.

CONCLUSION

Given the conflicting findings, and the methodological issues, it is not possible to draw a clear conclusion regarding the impact of carotid endarterectomy upon cognition. Future research which pays attention to these methodological factors is needed in order to adequately resolve the current debate.

Evidence of CNS impairment in HIV infection: clinical, neuropsychological, EEG, and MRI/MRS study

OBJECTIVES

To identify by clinical examination, EEG, MRI, and proton spectroscopy, and neuropsychological assessment the prevalence of signs of CNS involvement in patients infected with HIV, and to relate such findings to the evidence of immunosuppression.

METHODS

The design was a cross sectional analysis of a cohort of male patients with infected HIV with an AIDS defining diagnosis or low CD4 count (<350), and seropositive asymptomatic subjects, both groups being followed up in a longitudinal study. Control groups consisted of seronegative subjects from the same genitourinary medicine clinics.

RESULTS

This report sets out the cross sectional findings at the seventh visit in the longitudinal study. Patients with AIDS had more signs of neurological dysfunction, poorer performance on a neuropsychological test battery, were more likely to have an abnormal EEG, and to have abnormalities on MRI. They more often had cerebral atrophy, abnormal appearing white matter, and abnormal relaxometry and spectroscopy. There was little evidence of abnormality in seropositive people who had a CD4 count >350 compared with seronegative people from a similar background.

CONCLUSIONS

Detailed testing failed to disclose significant CNS impairment without immunosuppression in men infected with HIV. Findings from MRI and magnetic resonance spectroscopy (MRS) correlated with those of the neurological examination and neuropsychological assessment. A combination of such assessments offers a simple surrogate for studies of CNS involvement in HIV disease.

Proton MRS and quantitative MRI assessment of the short term neurological response to antiretroviral therapy in AIDS

OBJECTIVE

To investigate MRI and proton spectroscopy changes in five patients with HIV associated dementia complex (HADC) treated with antiretroviral therapy.

METHODS

Three markers were evaluated: (1) CSF/intracranial volume ratio; (2) T2 weighted signal ratio between parieto-occipital white and subcortical grey matter; and (3) metabolite ratios from long echo time (TE=135 ms) single voxel proton spectra of parieto-occipital white matter.

RESULTS

Spectroscopic changes indicated initial increases in N-acetyl/(N-acetyl + choline + creatine) ratio (NA/(NA+ Cho+Cr)) and progression of atrophy after initiation of antiretroviral therapy in four of five patients. When the neurological status of the patients subsequently deteriorated (two of five patients), the NA/(NA+Cho+Cr) ratio also declined.

CONCLUSIONS

Spectroscopic changes mirror reversible neuronal dysfunction. These objective, non-invasive techniques may be used for monitoring the neurological effects of antiretroviral drug therapy in patients with HADC.

A preliminary report on the neuropsychologic sequelae of human immunodeficiency virus

The neuropsychologic sequelae of acquired immunodeficiency syndrome and human immunodeficiency virus were studied by comparing the results of a neuropsychologic test battery administered to the following three groups of Danish homosexual men: 20 patients with acquired immunodeficiency syndrome, 20 asymptomatic subjects who tested positive for the human immunodeficiency virus, and a matched control group of 20 subjects who tested negative for the human immunodeficiency virus. The group with acquired immunodeficiency syndrome performed significantly worse than the control subjects on the tests measuring concentration, memory, and psychomotor speed. The group with human immunodeficiency virus performed significantly worse than the control subjects on the tests measuring verbal memory and psychomotor speed. On the other tests, their results varied. The study supports the hypothesis that not only patients with acquired immunodeficiency syndrome but also asymptomatic subjects with human immunodeficiency virus may be neuropsychologically impaired early in the course of the disease.

AIDS: clinical and ethical issues on a psychiatric unit

Using a case illustration, this paper describes how AIDS has affected psychiatric practice on an inpatient unit. The clinical, ethical and administrative issues are discussed from a multi-disciplinary perspective. The issues are discussed as 1. clinical issues (diagnostic and management), 2. effects on ward milieu, 3. staff issues, 4. family counselling and discharge planning and 5. administrative issues. It is important for inpatient staff to discuss these issues and develop clinical guidelines and administrative procedures that will help staff provide the highest level of care possible. Because every patient is potentially an HIV carrier, many of the solutions developed around AIDS related concerns should apply to all patients on a psychiatric ward.