Suicide in doctors: a study of risk according to gender, seniority and specialty in medical practitioners in England and Wales, 1979-1995

STUDY OBJECTIVE

To investigate the suicide risk of doctors in England and Wales, according to gender, seniority and specialty.

DESIGN

Retrospective cohort study. Suicide rates calculated by gender, age, specialty, seniority and time period. Standardised mortality ratios calculated for suicide (1991-1995), adjusted for age and sex.

SETTING

England and Wales.

SUBJECTS

Doctors in the National Health Service who died by suicide between 1979 and 1995, identified by death certificates. Population at risk based on Department of Health manpower data.

MAIN RESULTS

Two hundred and twenty three medical practitioners in the National Health Service who died by suicide or undetermined cause were identified. The annual suicide rates in male and female doctors were 19.2 and 18.8 per 100 000 respectively. The suicide rate in female doctors was higher than in the general population (SMR 201.8; 95% CI 99.7, 303.9), whereas the rate in male doctors was less than that of the general population (SMR 66.8; 95% CI 46.6, 87.0). The difference between the mortality ratios of the female and male doctors was statistically significant (p=0.01), although the absolute suicide risk was similar in the two genders. There were significant differences between specialties (p=0.0001), with anaesthetists, community health doctors, general practitioners and psychiatrists having significantly increased rates compared with doctors in general hospital medicine. There were no differences with regard to seniority and time period.

CONCLUSIONS

There is an increased risk of suicide in female doctors, but male doctors seem to be at less risk than men in the general population. The excess risk of suicide in female doctors highlights the need to tackle stress and mental health problems in doctors more effectively. The risk requires particular monitoring in the light of the very large increase in the numbers of women entering medicine.

Crystal structure of the histone acetyltransferase domain of the human PCAF transcriptional regulator bound to coenzyme A

The human p300/CBP-associating factor, PCAF, mediates transcriptional activation through its ability to acetylate nucleosomal histone substrates as well as transcriptional activators such as p53. We have determined the 2.3 A crystal structure of the histone acetyltransferase (HAT) domain of PCAF bound to coenzyme A. The structure reveals a central protein core associated with coenzyme A binding and a pronounced cleft that sits over the protein core and is flanked on opposite sides by the N- and C-terminal protein segments. A correlation of the structure with the extensive mutagenesis data for PCAF and the homologous yeast GCN5 protein implicates the cleft and the N- and C-terminal protein segments as playing an important role in histone substrate binding, and a glutamate residue in the protein core as playing an essential catalytic role. A structural comparison with the coenzyme-bound forms of the related N-acetyltransferases, HAT1 (yeast histone acetyltransferase 1) and SmAAT (Serratia marcescens aminoglycoside 3-N-acetyltransferase), suggests the mode of substrate binding and catalysis by these enzymes and establishes a paradigm for understanding the structure-function relationships of other enzymes that acetylate histones and transcriptional regulators to promote activated transcription.

Using serological measures to monitor changes in malaria transmission in Vanuatu

Background

With renewed interest in malaria elimination, island environments present unique opportunities to achieve this goal. However, as transmission decreases, monitoring and evaluation programmes need increasingly sensitive tools to assess Plasmodium falciparum and Plasmodium vivax exposure. In 2009, to assess the role of serological markers in evaluating malaria transmission, a cross-sectional seroprevalence study was carried out in Tanna and Aneityum, two of the southernmost islands of the Vanuatu archipelago, areas where malaria transmission has been variably reduced over the past few decades.

Methods

Malaria transmission was assessed using serological markers for exposure to P. falciparum and P. vivax. Filter blood spot papers were collected from 1,249 people from Tanna, and 517 people from Aneityum to assess the prevalence of antibodies to two P. falciparum antigens (MSP-1₁₉ and AMA-1) and two P. vivax antigens (MSP-1₁₉ and AMA-1). Age-specific prevalence was modelled using a simple catalytic conversion model based on maximum likelihood to generate a community seroconversion rate (SCR).

Results

Overall seropositivity in Tanna was 9.4%, 12.4% and 16.6% to P. falciparum MSP-1₁₉, AMA-1 and Schizont Extract respectively and 12.6% and 15.0% to P. vivax MSP-1₁₉ and AMA-1 respectively. Serological results distinguished between areas of differential dominance of either P. vivax or P. falciparum and analysis of age-stratified results showed a step in seroprevalence occurring approximately 30 years ago on both islands, indicative of a change in transmission intensity at this time. Results from Aneityum suggest that several children may have been exposed to malaria since the 2002 P. vivax epidemic.

Conclusion

Seroepidemiology can provide key information on malaria transmission for control programmes, when parasite rates are low. As Vanuatu moves closer to malaria elimination, monitoring changes in transmission intensity and identification of residual malaria foci is paramount in order to concentrate intervention efforts.

Overcrowding and understaffing in modern health-care systems: key determinants in meticillin-resistant Staphylococcus aureus transmission

Recent decades have seen the global emergence of meticillin-resistant Staphylococcus aureus (MRSA), causing substantial health and economic burdens on patients and health-care systems. This epidemic has occurred at the same time that policies promoting higher patient throughput in hospitals have led to many services operating at, or near, full capacity. A result has been limited ability to scale services according to fluctuations in patient admissions and available staff, and hospital overcrowding and understaffing. Overcrowding and understaffing lead to failure of MRSA control programmes via decreased health-care worker hand-hygiene compliance, increased movement of patients and staff between hospital wards, decreased levels of cohorting, and overburdening of screening and isolation facilities. In turn, a high MRSA incidence leads to increased inpatient length of stay and bed blocking, exacerbating overcrowding and leading to a vicious cycle characterised by further infection control failure. Future decision making should use epidemiological and economic evidence to evaluate the effect of systems changes on the incidence of MRSA infection and other adverse events.

Aggregation and metal-binding properties of mutant forms of the amyloid A beta peptide of Alzheimer's disease

The fibrillogenic properties of Alzheimer's A beta peptides corresponding to residues 1-40 of the normal human sequence and to two mutant forms containing the replacement Ala21 to Gly or Glu22 to Gln were compared. At pH 7.4 and 37 degrees C the Gln22 peptide was found to aggregate and precipitate from solution faster than the normal A beta, whereas the Gly21 peptide aggregated much more slowly. Electron microscopy showed that the aggregates all had fibrillar structures. Circular dichroism spectra of these peptides revealed that aggregation of the normal and Gln22 sequences was associated with spectral changes consistent with a transformation from random coil to beta sheet, whereas the spectrum of the Gly21 peptide remained almost unchanged during a period in which little or no aggregation occurred. When immobilised by spotting onto nitrocellulose membranes the peptides bound similar amounts of the radioisotope 65Zn2+. Of several competing metal ions, tested at 20x the concentration of Zn2+, Cu2+ displaced > 95% of the radioactivity from all three peptides and Ni2+ produced >50% displacement in each case. Some other metal ions tested caused lesser displacement, but Fe2+ and Al3+ were without effect. In a saturation binding assay, a value of 3.2 microM was obtained for the binding of Zn2+ to A beta but our data provided no evidence for a reported higher affinity site (107 nM). The results suggest that the neuropathology associated with the Gly21 mutation is not due to enhanced fibrillogenic or different metal-binding properties of the peptide and that the binding of zinc to amyloid peptides is not a specific phenomenon.

Doctors who kill themselves: a study of the methods used for suicide

Medical practitioners have a relatively high rate of suicide. Death entry data for doctors who died by suicide or undetermined cause between 1979 and 1995 in England and Wales were used to compare methods used for suicide by doctors with those used by the general population. Methods used were analysed according to gender, occupational status and speciality, to assess the extent to which access to dangerous means influences the pattern of suicide. Self-poisoning with drugs was more common in the doctors than in general population suicides (57% vs. 26.6%; OR=3.65, 95% CI 2.85-4. 68), including in retired doctors. Barbiturates were the most frequent drugs used. Half of the anaesthetists who died used anaesthetic agents. Self-cutting was also more frequently used as a method of suicide. The finding that the greater proportion of suicide deaths in doctors were by self-poisoning may reflect the fact that doctors have ready access to drugs, and have knowledge of which drugs and doses are likely to cause death. The specific finding that a large proportion of suicides in anaesthetists involved anaesthetic agents supports this explanation. Availability of method may be a factor contributing to the relatively high suicide rate of doctors. This fact might influence clinical management of doctors who are known to be depressed or suicidal.

Detection of Mycobacterium bovis infection in skin test-negative cattle with an assay for bovine interferon-gamma

Mycobacterium bovis was isolated from respiratory secretions and lymph nodes from 15 skin test-negative cattle which exhibited interferon-gamma responses. These field cases, identified by blood testing, constituted a significant proportion of skin test-negative cattle which had been subjected to extensive post mortem examinations. Typical tuberculous lesions were found in seven of them. The consequences of cattle with early tuberculosis infection not being detected by traditional tuberculin testing are considered.

HCV treatment rates and sustained viral response among people who inject drugs in seven UK sites: real world results and modelling of treatment impact

Hepatitis C virus (HCV) antiviral treatment for people who inject drugs (PWID) could prevent onwards transmission and reduce chronic prevalence. We assessed current PWID treatment rates in seven UK settings and projected the potential impact of current and scaled-up treatment on HCV chronic prevalence. Data on number of PWID treated and sustained viral response rates (SVR) were collected from seven UK settings: Bristol (37-48% HCV chronic prevalence among PWID), East London (37-48%), Manchester (48-56%), Nottingham (37-44%), Plymouth (30-37%), Dundee (20-27%) and North Wales (27-33%). A model of HCV transmission among PWID projected the 10-year impact of (i) current treatment rates and SVR (ii) scale-up with interferon-free direct acting antivirals (IFN-free DAAs) with 90% SVR. Treatment rates varied from <5 to over 25 per 1000 PWID. Pooled intention-to-treat SVR for PWID were 45% genotypes 1/4 [95%CI 33-57%] and 61% genotypes 2/3 [95%CI 47-76%]. Projections of chronic HCV prevalence among PWID after 10 years of current levels of treatment overlapped substantially with current HCV prevalence estimates. Scaling-up treatment to 26/1000 PWID annually (achieved already in two sites) with IFN-free DAAs could achieve an observable absolute reduction in HCV chronic prevalence of at least 15% among PWID in all sites and greater than a halving in chronic HCV in Plymouth, Dundee and North Wales within a decade. Current treatment rates among PWID are unlikely to achieve observable reductions in HCV chronic prevalence over the next 10 years. Achievable scale-up, however, could lead to substantial reductions in HCV chronic prevalence.

Effects of the mutations Glu22 to Gln and Ala21 to Gly on the aggregation of a synthetic fragment of the Alzheimer's amyloid beta/A4 peptide

We assessed the fibrillogenic properties of synthetic peptides corresponding to residues 13-26 of beta/A4 amyloid, containing either the normal sequence (beta 13 26) or the mutations Glu22 to Gln (beta 13-26Q22) and Ala21 to Gly (beta 13-26G21). The kinetics of aggregation were monitored at 37 degrees C and pH 7.4 by measuring the amount of peptide remaining in solution, using reverse-phase high performance liquid chromatography. Negative stain electron microscopy revealed that all of the peptides formed fibrils. However, beta 13-26Q22 showed greatly accelerated fibril formation compared to the other two. The results suggest that the Q22 mutation confers increased amyloidogenic properties on the beta/A4 peptide, whereas the G21 mutation acts by a different pathogenic mechanism.

Identifying symptoms of ovarian cancer: a qualitative and quantitative study

Introduction

Symptoms of ovarian cancer are often vague and consequently a high proportion of women with ovarian cancer are not referred to the appropriate clinic.

Objective

To identify diagnostic factors for ovarian cancer.

Design

A qualitative and quantitative study.

Setting

Four UK hospitals.

Sample

One hundred and twenty-four women referred to hospital with suspected ovarian malignancy.

Methods

Women were interviewed prior to diagnosis (n = 63), or soon after. A thematic analysis was conducted. Emergent symptoms were quantitatively analysed to identify distinguishing features of ovarian cancer.

Main outcomes

Symptoms in women with and without ovarian cancer.

Results

Diagnoses comprised 44 malignancies, 59 benign gynaecological pathologies and 21 normal findings. Of the malignancies, 25 women had stage III or more disease, with an average age of 59 years. The benign/normal cohort was significantly younger (48 years). Multivariate analysis revealed persistent abdominal distension (OR 5.2, 95% CI 1.3–20.5), postmenopausal bleeding (OR 9.2, 95% CI 1.1–76.1), appetite loss (OR 3.2, 95% CI 1.1–9.2), early satiety (OR 5.0, 95% CI 1.6–15.7) and progressive symptoms (OR 3.6, 95% CI 1.3–9.8) as independent, statistically significant variables associated with ovarian cancer. Fluctuating distension was not associated with ovarian cancer (OR 0.4, 95% CI 0–4.1). Women frequently used the term bloating, but this represented two distinct events: persistent abdominal distension and fluctuating distension/discomfort.

Conclusions

Ovarian cancer is not a silent killer. Clinicians should distinguish between persistent and fluctuating distension. Recognition of the significance of symptoms described by women could lead to earlier and more appropriate referral.

Please cite this paper as: Bankhead C, Collins C, Stokes-Lampard H, Rose P, Wilson S, Clements A, Mant D, Kehoe S, Austoker J. Identifying symptoms of ovarian cancer: a qualitative and quantitative study. BJOG 2008;115:1008–1014.

Crystal structure of the mouse p53 core DNA-binding domain at 2.7 A resolution

The p53 tumor suppressor is a sequence-specific DNA-binding protein that activates transcription in response to DNA damage to promote cell cycle arrest or apoptosis. The p53 protein functions in a tetrameric form in vivo and contains four domains including an N-terminal transcriptional activation domain, a C-terminal regulatory domain, a tetramerization domain, and a central core DNA-binding domain that is the site of the majority of tumor-derived mutations. Here we report the 2.7-A crystal structure of the mouse p53 core domain. Like the human p53 core domain in complex with DNA, the mouse p53 core domain adopts an immunoglobulin-like beta sandwich architecture with a series of loops and short helices at opposite ends of the beta sandwich. Comparison of the DNA-bound and DNA-free p53 core domains reveals that while the central beta sandwich architecture remains largely unchanged, a loop region important for DNA binding undergoes significant rearrangement. Although this loop region mediates major groove DNA contacts in the DNA-bound structure, it adopts a conformation that is incompatible with DNA binding in the DNA-free structure. Interestingly, crystals of the DNA-free core domain contain a noncrystallographic trimer with three nearly identical subunit-subunit (dimer) contacts. These dimer contacts align the p53 core domains in a way that is incompatible with simultaneous DNA binding by both protomers of the dimer. Surprisingly, similar dimer contacts are observed in crystals of the human p53 core domain with DNA in which only one of the three p53 protomers in the asymmetric unit cell is specifically bound to DNA. We propose that the p53 core domain dimer that is seen in the crystals described here represents a physiologically relevant inactive form of p53 that must undergo structural rearrangement for sequence-specific DNA binding.

Spatial patterns and socioecological drivers of dengue fever transmission in Queensland, Australia

BACKGROUND

Understanding how socioecological factors affect the transmission of dengue fever (DF) may help to develop an early warning system of DF.

OBJECTIVES

We examined the impact of socioecological factors on the transmission of DF and assessed potential predictors of locally acquired and overseas-acquired cases of DF in Queensland, Australia.

METHODS

We obtained data from Queensland Health on the numbers of notified DF cases by local government area (LGA) in Queensland for the period 1 January 2002 through 31 December 2005. Data on weather and the socioeconomic index were obtained from the Australian Bureau of Meteorology and the Australian Bureau of Statistics, respectively. A Bayesian spatial conditional autoregressive model was fitted at the LGA level to quantify the relationship between DF and socioecological factors.

RESULTS

Our estimates suggest an increase in locally acquired DF of 6% [95% credible interval (CI): 2%, 11%] and 61% (95% CI: 2%, 241%) in association with a 1-mm increase in average monthly rainfall and a 1°C increase in average monthly maximum temperature between 2002 and 2005, respectively. By contrast, overseas-acquired DF cases increased by 1% (95% CI: 0%, 3%) and by 1% (95% CI: 0%, 2%) in association with a 1-mm increase in average monthly rainfall and a 1-unit increase in average socioeconomic index, respectively.

CONCLUSIONS

Socioecological factors appear to influence the transmission of DF in Queensland, but the drivers of locally acquired and overseas-acquired DF may differ. DF risk is spatially clustered with different patterns for locally acquired and overseas-acquired cases.

Chronic fatigue syndrome: a qualitative investigation of patients' beliefs about the illness

The chronic fatigue syndrome is a disabling chronic condition of uncertain cause. Previous studies have found that patients seen in hospital clinics with the syndrome often strongly believe that their illness is physical in nature and minimize the role of psychological and social factors. There is also evidence that patients cope by avoiding activity. However, almost all of these studies have assessed illness beliefs only by questionnaire. The aim of this study was to explore the nature and origin of illness beliefs in more detail using in-depth interviews and a qualitative analysis of patient responses. Sixty-six consecutive referrals meeting Oxford criteria for chronic fatigue syndrome were recruited. Analysis of responses indicated that, whereas the most commonly described explanation for the illness was a physical one, more than half the patients also believed "stress" had played a role. Patients believed that they could partially control the symptoms by reducing activity but felt helpless to influence the physical disease process and hence the course of the illness. Patients reported that they had arrived at these beliefs about the illness after prolonged reflection on their own experience combined with the reading of media reports, self help books, and patient group literature. The views of health professionals played a relatively small role. There is potentially a considerable opportunity to help patients arrive at a wider and more enabling explanation of their illness when they first present to primary care.

Clinical supervision: insider reports of a private world

An exploratory study, funded by the Department of Health, London and the Scottish Home and Health Department, Edinburgh, was conducted over an 18-month period to provide an informed view on possible assessment tools that could be used to assess the impact of clinical supervision (CS) in nursing and to report on the CS activities in 23 selected sites in England and Scotland. The study not only examined the utility of several standardized research instruments, to be reported separately, but also explored the experience of a small sub-sample of nurses (n = 34) engaged in CS, as supervisors and supervisees. Interviews were undertaken to help better understand some of the issues involved around the domains of structure, process and outcome. Respondents reported an enthusiasm for the opportunity to talk meaningfully to a trusted colleague about their personal circumstances at work. Such opportunities were particularly welcomed by nurses who wished to reflect upon their own practice with patients, especially when dealing with their clinical conditions which were upsetting, or otherwise challenging, and sometimes harrowing. Substantive and methodological areas of interest for future research are suggested.

Metformin in prostate cancer: two for the price of one

BACKGROUND

Androgen deprivation therapy (ADT) for prostate cancer treatment induces a metabolic syndrome, which may contribute to non-cancer-related morbidity and mortality. Metformin may abrogate these effects. Additionally, metformin has potential antineoplastic activity in various malignancies including prostate cancer.

MATERIALS AND METHODS

A literature review using PubMed with the keywords: AMPK, androgen deprivation therapy, insulin resistance, metabolic syndrome, metformin and prostate cancer was undertaken.

RESULTS

This overview will look at the current evidence linking ADT and metabolic syndrome while discussing ongoing clinical trials under way assessing the effectiveness of metformin in abrogating these effects. The potential antineoplastic activity of metformin, mediated by multiple proposed mechanisms based on evidence from preclinical and clinical studies, will also be elucidated in this review.

CONCLUSIONS

Overall available data support the potential dual benefit of metformin on ADT-induced metabolic syndrome and in its antineoplastic activity in prostate cancer, justifying the need for ongoing clinical trials to confirm these effects as the evidence currently available for standard practice is lacking.

Spatial epidemiology of Plasmodium vivax, Afghanistan

Plasmodium vivax is endemic to many areas of Afghanistan. Geographic analysis helped highlight areas of malaria risk and clarified ecologic risk factors for transmission. Remote sensing enabled development of a risk map, thereby providing a valuable tool to help guide malaria control strategies.

Suicide in female nurses in England and Wales

BACKGROUND

Female nurses appear to have an increased risk of suicide but the reasons are unknown.

METHOD

We have concluded a study of nurse suicides (N = 106) in England and Wales, including a psychological autopsy study (N = 42) and case-control comparison with living nurses (N = 84).

RESULTS

Nearly three-quarters of the nurse suicides had previous contact with psychiatric services and almost half had been psychiatric in-patients in the past. There were particularly marked differences between the cases and controls for current psychiatric disorder (90.5% v. 7.1%, OR = 68.5), personality disorder (38.1% v. 12%, OR = 32), and history of deliberate self-harm (71.4% v. 2.4%, OR = 58.5). Family background and social factors (especially concerning interpersonal relationships) also distinguished the two groups. Smoking and serious alcohol abuse were much more frequent in the suicides. There was some indication that while many of the suicides were in contact with psychiatric services, care may not have been optimal in some cases.

CONCLUSIONS

The most important strategies for suicide prevention in nurses are in prevention, detection and management of psychiatric disorders. In assessing suicide risk a history of DSH and the presence of comorbid psychiatric and personality disorders are particularly important.

Dengue fever and El Nino/Southern Oscillation in Queensland, Australia: a time series predictive model

BACKGROUND

It remains unclear over whether it is possible to develop an epidemic forecasting model for transmission of dengue fever in Queensland, Australia.

OBJECTIVES

To examine the potential impact of El Niño/Southern Oscillation on the transmission of dengue fever in Queensland, Australia and explore the possibility of developing a forecast model of dengue fever.

METHODS

Data on the Southern Oscillation Index (SOI), an indicator of El Niño/Southern Oscillation activity, were obtained from the Australian Bureau of Meteorology. Numbers of dengue fever cases notified and the numbers of postcode areas with dengue fever cases between January 1993 and December 2005 were obtained from the Queensland Health and relevant population data were obtained from the Australia Bureau of Statistics. A multivariate Seasonal Auto-regressive Integrated Moving Average model was developed and validated by dividing the data file into two datasets: the data from January 1993 to December 2003 were used to construct a model and those from January 2004 to December 2005 were used to validate it.

RESULTS

A decrease in the average SOI (ie, warmer conditions) during the preceding 3-12 months was significantly associated with an increase in the monthly numbers of postcode areas with dengue fever cases (beta=-0.038; p = 0.019). Predicted values from the Seasonal Auto-regressive Integrated Moving Average model were consistent with the observed values in the validation dataset (root-mean-square percentage error: 1.93%).

CONCLUSIONS

Climate variability is directly and/or indirectly associated with dengue transmission and the development of an SOI-based epidemic forecasting system is possible for dengue fever in Queensland, Australia.

Imprinting and anticipation. Are they relevant to genetic studies of schizophrenia?

Among 29 multiply affected pedigrees, age of onset among parents and offspring was examined for evidence of both anticipation and genomic imprinting. The results do not suggest that either mechanism is operating in schizophrenia, but only very large effects can be confidently excluded.

Do patients with "pure" chronic fatigue syndrome (neurasthenia) have abnormal sleep?

OBJECTIVE

To determine whether patients with "pure" chronic fatigue syndrome (neurasthenia) have sleep abnormalities which may contribute to subjective measures of daytime fatigue.

METHOD

Sleep characteristics of 20 patients meeting research criteria for chronic fatigue syndrome (CFS) but not depression, anxiety, or sleep disorder were compared with sleep characteristics of 20 healthy subjects matched for age and sex. Measures of sleep included a) subjective interview reports and sleep diaries and b) home-based polysomnography.

RESULTS

Patients with CFS complained of poor quality unrefreshing sleep. They also napped during the day. Polysomnograph data showed no difference in actual nocturnal sleep time between the two groups although patients with CFS spent significantly longer in bed (p < .01), slept less efficiently (p < .03), and spent longer awake after sleep onset (p < .05). The polysomnographs of seven patients with CFS and one healthy subject were regarded as significantly abnormal. Five patients and one healthy subject had difficulty maintaining sleep. One patient had a disorder of both initiating and maintaining sleep and one patient woke early.

CONCLUSIONS

Patients with "pure" CFS complain of unrefreshing sleep but only a minority have a clearly abnormal polysomnograph. The most common abnormality is of long periods spent awake after initial sleep onset. Although sleep abnormalities may play a role in the etiology of CFS, they seem to be unlikely to be an important cause of daytime fatigue in the majority of patients. However, pharmacological and behavioral methods that improve sleep quality may be an important component of a pragmatically based treatment package for patients who do have abnormal sleep.

Spatiotemporal analysis of indigenous and imported dengue fever cases in Guangdong province, China

BACKGROUND

Dengue fever has been a major public health concern in China since it re-emerged in Guangdong province in 1978. This study aimed to explore spatiotemporal characteristics of dengue fever cases for both indigenous and imported cases during recent years in Guangdong province, so as to identify high-risk areas of the province and thereby help plan resource allocation for dengue interventions.

METHODS

Notifiable cases of dengue fever were collected from all 123 counties of Guangdong province from 2005 to 2010. Descriptive temporal and spatial analysis were conducted, including plotting of seasonal distribution of cases, and creating choropleth maps of cumulative incidence by county. The space-time scan statistic was used to determine space-time clusters of dengue fever cases at the county level, and a geographical information system was used to visualize the location of the clusters. Analysis were stratified by imported and indigenous origin.

RESULTS

1658 dengue fever cases were recorded in Guangdong province during the study period, including 94 imported cases and 1564 indigenous cases. Both imported and indigenous cases occurred more frequently in autumn. The areas affected by the indigenous and imported cases presented a geographically expanding trend over the study period. The results showed that the most likely cluster of imported cases (relative risk = 7.52, p < 0.001) and indigenous cases (relative risk = 153.56, p < 0.001) occurred in the Pearl River Delta Area; while a secondary cluster of indigenous cases occurred in one district of the Chao Shan Area (relative risk = 471.25, p < 0.001).

CONCLUSIONS

This study demonstrated that the geographic range of imported and indigenous dengue fever cases has expanded over recent years, and cases were significantly clustered in two heavily urbanised areas of Guangdong province. This provides the foundation for further investigation of risk factors and interventions in these high-risk areas.

Involvement of the medial septum in stress-induced relapse to heroin seeking in rats

Intermittent footshock stress has been shown to reinstate extinguished drug-taking behaviour in rats, but the brain areas involved in this effect are to a large degree unknown. Here we studied the role of the septum in stress-induced reinstatement of heroin seeking. Rats were trained to self-administer heroin for 9-10 days (three 3-h sessions per day, 0.1 mg/kg per infusion). Following training, extinction sessions were given for 8-13 days by substituting saline for heroin, and then tests for reinstatement of heroin seeking were carried out. Reversible inactivation of the medial septum with tetrodotoxin (TTX; 1-5 ng, infused 25-40 min before the test sessions) reliably reinstated heroin seeking, mimicking the effect of 15 min of intermittent footshock. This effect of TTX was not observed after infusions made 1.5 mm dorsally into the lateral septum. In other experiments, it was found that infusions of a low, subthreshold dose of TTX (0.5 ng) into the medial septum, when combined with 2 min of footshock that in itself was ineffective, reinstated heroin seeking. Furthermore, electrical stimulation (400 microA pulses, 100 micros duration, 100 Hz frequency) of the medial septum during exposure to 10 min of intermittent footshock attenuated footshock-induced reinstatement of heroin seeking. These data suggest a role for the medial septum in stress-induced relapse to drug seeking. The septum is thought to be involved in neuronal processes underlying behavioural inhibition, thus we speculate that stressors provoke relapse by interfering with these processes.

Basal activity of the hypothalamic-pituitary-adrenal axis in patients with the chronic fatigue syndrome (neurasthenia)

BACKGROUND

Impairments in both basal activity and activation of the hypothalamic-pituitary-adrenal axis (HPA) have been reported in chronic fatigue syndrome (CFS; neurasthenia). We sought to replicate these findings and examined basal activity of the HPA in a carefully selected sample of patients with CFS.

METHODS

Basal activity of the HPA was assessed using salivary and urinary cortisol collection over a 24-hour period in 22 (12 male; 10 female) patients meeting criteria for CFS and appropriate controls.

RESULTS

Salivary and urinary cortisol measures did not differ between CFS patients and controls.

CONCLUSIONS

Basal activity of the HPA was not reduced in CFS patients. Reasons for the failure to replicate previous findings are discussed.