Positive replication and linkage disequilibrium mapping of the chromosome 21q22.1 malaria susceptibility locus

Four cytokine receptor genes are located on Chr21q22.11, encoding the alpha and beta subunits of the interferon-alpha receptor (IFNAR1 and IFNAR2), the beta subunit of the interleukin 10 receptor (IL10RB) and the second subunit of the interferon-gamma receptor (IFNGR2). We previously reported that two variants in IFNAR1 were associated with susceptibility to malaria in Gambians. We now present an extensive fine-scale mapping of the associated region utilizing 45 additional genetic markers obtained from public databases and by sequencing a 44 kb region in and around the IFNAR1 gene in 24 Gambian children (12 cases/12 controls). Within the IFNAR1 gene, a newly studied C --> G single-nucleotide polymorphism (IFNAR1 272354c-g) at position -576 relative to the transcription start was found to be more strongly associated with susceptibility to severe malaria. Association was observed in three populations: in Gambian (P=0.002), Kenyan (P=0.022) and Vietnamese (P=0.005) case-control studies. When all three studies were combined, using the Mantel-Haenszel test, the presence of IFNAR1 -576G was associated with a substantially elevated risk of severe malaria (N=2444, OR=1.38, 95% CI: 1.17-1.64; P=1.7 x 10(-4)). This study builds on previous work to further highlight the importance of the type-I interferon pathway in malaria susceptibility and illustrates the utility of typing SNPs within regions of high linkage disequilibrium in multiple populations to confirm initial positive associations.

Does smoking influence the type of age related macular degeneration causing visual impairment?

AIMS

To assess the influence of smoking on the type of age related macular degeneration (AMD) lesion causing visual impairment in a large cohort of patients with AMD at a tertiary referral UK centre.

METHODS

Prospective, observational, cross sectional study to analyse smoking data on 711 subjects, of western European origin, in relation to the type of AMD lesion present. Colour fundus photographs were graded according to a modified version of the international classification. Multiple logistic regression analysis was performed, adjusting for age and sex using the statistical package SPSS ver 9.0 for Windows. chi(2) tests were also used to assess pack year and ex-smoker data.

RESULTS

578 subjects were graded with neovascular AMD and 133 with non-neovascular AMD. There was no statistically significant association found between smoking status or increasing number of pack years and type of AMD lesion. The odds of "current smokers" compared to "non-smokers" developing neovascular rather than non-neovascular AMD when adjusted for age and sex was 1.88 (95% CI: 0.91 to 3.89; p = 0.09).

CONCLUSIONS

Smoking is known to be a risk factor for AMD and this study suggests that smokers are at no more risk of developing neovascular than atrophic lesions.

Safety of recombinant fowlpox strain FP9 and modified vaccinia virus Ankara vaccines against liver-stage P. falciparum malaria in non-immune volunteers

The ability to generate potent antigen-specific T cell responses by vaccination has been a major hurdle in vaccinology. Vaccinia virus and avipox viruses have been shown to be capable of expressing antigens in mammalian cells and can induce a protective immune response against several mammalian pathogens. We report on two such vaccine constructs, modified vaccinia virus Ankara and FP9 (an attenuated fowlpox virus) both expressing the pre-erythrocytic malaria antigen thrombospondin-related adhesion protein and a string of CD8+ epitopes (ME-TRAP). In prime-boost combinations in a mouse model MVA and FP9 are highly immunogenic and induce substantial protective efficacy. A series of human clinical trials using the recombinant MVA and FP9 malaria vaccines encoding ME-TRAP, both independently and in prime-boost combinations with or without the DNA vaccine DNA ME-TRAP, has shown them to be both immunogenic for CD8+ T cells and capable of inducing protective efficacy. We report here a detailed analysis of the safety profiles of these viral vectors and show that anti-vector antibody responses induced by the vectors are generally low to moderate. We conclude that these vectors are safe and show acceptable side effect profiles for prophylactic vaccination.

Case of cryptic malaria

We report a case of falciparum malaria in a renal transplant patient with no history of foreign travel. Three weeks previously she had been a hospital inpatient with cellulitis and had stayed on the same ward as a man with falciparum malaria acquired in Nigeria. There were no cases of malaria in other patients on the ward at the same time. The parasites from the two cases were genotypically indistinguishable. Despite a thorough investigation, reviewed by an expert external panel, no clear route of infection between the cases was identified. Patients with malaria should be considered highly infectious by the parenteral route. They should be managed with the infection control precautions used for patients with bloodborne virus infections. Our case reinforces the need for high levels of compliance with universal infection control procedures.

Age as a determinant of survival in HIV infection

Age is a major determinant of mortality for many diseases including HIV infection, yet the effect of age is rarely studied directly. In this article, we review what is known about the effect of age at seroconversion on HIV disease progression and survival prior to the widespread use of HAART before describing appropriate methods for adjusting for background mortality in more detail. We then investigate the impact of HAART on the effect of age at seroconversion on mortality and consider the estimation of the age effect in seroprevalent cohorts with regard to lack of knowledge of the true age at infection. Finally, we discuss mechanisms by which age at seroconversion might impact on disease progression and death. Throughout, we use published results by the Collaborative Group on AIDS Incubation and HIV Survival (CGAIHS), and published results and data from the Concerted Action on SeroConversion to AIDS and Death in Europe (CASCADE) for illustration.

Training in general (internal) medicine alone

A freestanding training programme for general (internal) medicine (G(I)M) alone was established in the Oxford deanery four years ago. The programme was designed to provide three years' training post-MRCP for specialist registrars, selected in open competition, and covers all aspects of acute medical care including four months in intensive care. The first four to complete training have achieved consultant level appointments. The programme also attracted a number of trainees who wished to obtain appropriate qualifications in high dependency and critical care medicine. The programme offers the opportunity to create specialists properly trained in G(I)M who will be able to continue to provide an important service as specialists or practising as consultants in G(I)M alone.

Decreased tryptophan availability but normal post-synaptic 5-HT2c receptor sensitivity in chronic fatigue syndrome

BACKGROUND

Chronic fatigue syndrome (CFS) has been associated with increased prolactin (PRL) responses to the serotonin (5-HT) releasing agent fenfluramine. It is not known whether this abnormality is due to increased 5-HT release or heightened sensitivity of post-synaptic 5-HT receptors.

METHODS

We measured the increase in plasma PRL produced by the directly acting 5-HT receptor agonist, m-chlorophenylpiperazine (mCPP), in patients with CFS and healthy controls. We also compared the ability of mCPP to lower slow wave sleep (SWS) in the sleep polysomnogram of both subject groups. Finally, we measured plasma amino-acid levels to determine whether tryptophan availability differed between CFS subjects and controls.

RESULTS

mCPP elevated plasma PRL equivalently in patients with CFS and controls. Similarly, the decrease in SWS produced by mCPP did not differ between the two subject groups. Plasma-free tryptophan was significantly decreased in CFS.

CONCLUSIONS

The sensitivity of post-synaptic 5-HT2c receptors is not increased in patients with CFS. This suggests that the increased PRL response to fenfluramine in CFS is due to elevated activity of pre-synaptic 5-HT neurones. This change is unlikely to be due to increased peripheral availability of tryptophan.

A study of three cases of familial related agenesis of the corpus callosum

This paper provides data on a family in which three members, all female, have been diagnosed as having agenesis of the corpus callosum. That all three acallosal individuals came from the same family and showed relatively uniform neuropsychological impairment and could be compared in similar terms with their "callosal" siblings, also female, provides a unique sample. Inter-hemispheric transfer, psychometric measures, and motor and cognitive function were examined in the acallosal individuals, all of whom had borderline to low-average intelligence, with results compared to their non-acallosal siblings. The data indicated that all acallosal individuals exhibited deficits with the cognitive tests indicating difficulties of inter-hemispheric transfer of tactile information, difficulties in some areas of memory and, at least as far as the children are concerned, a marked difference in Verbal IQ and Performance IQ.

Effect of phenobarbital on seizure frequency and mortality in childhood cerebral malaria: a randomised, controlled intervention study

BACKGROUND

Seizures commonly complicate cerebral malaria and are associated with an increased risk of death and neurological sequelae. We undertook a randomised study to assess the efficacy of intramuscular phenobarbital in preventing seizures in childhood cerebral malaria.

METHODS

Children with cerebral malaria admitted to one hospital in Kilifi, Kenya, were randomly assigned a single intramuscular dose of phenobarbital (20 mg/kg) or identical placebo. Clinical tolerance was assessed at the start of the trial, with particular reference to respiratory depression and hypotension. Seizures were timed and recorded, and treated in a standard way. Plasma phenobarbital concentrations were measured. Analyses were by intention to treat.

FINDINGS

440 children with cerebral malaria were admitted to the hospital; 100 were not recruited to the study. Of the remaining 340, 170 received phenobarbital and 170 placebo. The drug was adequately absorbed and well tolerated. Seizure frequency was significantly lower in the phenobarbital group than in the placebo group (18 [11%] vs 46 [27%] children had three or more seizures of any duration; odds ratio 0.32 [95% CI 0.18-0.58]) but mortality was doubled (30 [18%] vs 14 [8%] deaths; 2.39 [1.28-4.64]). The frequency of respiratory arrest was higher in the phenobarbital group than in the placebo group, and mortality was greatly increased in children who received phenobarbital plus three or more doses of diazepam (odds ratio 31.7 [1.2-814]).

INTERPRETATION

In children with cerebral malaria, phenobarbital 20 mg/kg provides highly effective seizure prophylaxis but is associated with an unacceptable increase in mortality. Use of this dose cannot, therefore, be recommended.

Zidovudine (AZT) versus AZT plus didanosine (ddI) versus AZT plus zalcitabine (ddC) in HIV infected adults

BACKGROUND

Zidovudine (AZT) monotherapy was the first antiretroviral drug to be tested widely. The next two drugs to be developed were didanosine (ddI) and zalcitabine (ddC).

OBJECTIVES

To assess the effects of zidovudine (AZT), zidovudine plus didanosine (ddI) and zidovudine plus zalcitabine (ddC) on HIV disease progression and survival.

SEARCH STRATEGY

Investigators and pharmaceutical companies were contacted, and MEDLINE searches were supplemented by searching conference abstracts.

SELECTION CRITERIA

Randomised controlled trials comparing any two of AZT plus ddI, AZT plus ddC or AZT alone in participants with or without AIDS which collected information on deaths and new AIDS events.

DATA COLLECTION AND ANALYSIS

Individual patient data with, wherever possible, follow-up obtained beyond that previously published were obtained and checked for internal consistency and consistency with any published reports; any apparent discrepancies were resolved with the trialists. Time to death and to disease progression (defined as a new AIDS-defining event or prior death) were analysed on an intention to treat basis, stratified to avoid direct comparisons between participants in different trials.

MAIN RESULTS

Six trials were included in the meta-analysis. During a median follow-up of 29 months, 2904 individuals progressed, of whom 1850 died. The addition of ddI to AZT delayed both progression (RR 0.74; 95% CI 0.67 to 0.82, P<0.0001) and death (RR 0.72; 95% CI 0.64 to 0.82, P<0.0001). Likewise, the addition of ddC to AZT also delayed progression (RR 0. 86; 95% CI 0.78 to 0.94, P=0.001) and death (RR 0.87; 95% CI 0.77 to 0.98, P=0.02). After 3 years the estimated percentages alive and without a new AIDS event were 53% for AZT+ddI, 49% for AZT+ddC and 44% for AZT alone; the percentages alive were 68%, 63% and 59% respectively. Five of the six trials involved randomised comparisons of AZT+ddI versus AZT+ddC: in these, the AZT+ddI regimen had greater effects on disease progression (P=0.004) and death (P=0.009).

REVIEWER'S CONCLUSIONS

The use of ddI and, to a lesser extent, ddC delayed both HIV disease progression and death, at least when added to AZT.

Immediate versus deferred zidovudine (AZT) in asymptomatic or mildly symptomatic HIV infected adults

BACKGROUND

Zidovudine (AZT) monotherapy was the first antiretroviral drug to be tested widely. Subsequent trials in asymptomatic or early symptomatic HIV infection indicated short-term delays in disease progression with AZT, but not improved survival.

OBJECTIVES

To assess the effects of immediate versus deferred zidovudine (AZT) on HIV disease progression and survival.

SEARCH STRATEGY

Investigators and pharmaceutical companies were contacted, and MEDLINE searches were supplemented by searching conference abstracts.

SELECTION CRITERIA

Randomised controlled trials comparing immediate versus deferred AZT in participants without AIDS which prospectively collected deaths and new AIDS events.

DATA COLLECTION AND ANALYSIS

Individual patient data with, wherever possible, follow-up obtained beyond that previously published was obtained and checked for internal consistency and consistency with any published reports; any apparent discrepancies were resolved with the trialists. Time to death and to disease progression (defined as a new AIDS-defining event or prior death) were analysed on an intention to treat basis, stratified to avoid direct comparisons between participants in different trials.

MAIN RESULTS

Nine trials were included in the meta-analysis. During a median follow-up of 50 months, 1908 individuals developed disease progression, of whom 1351 died. In the deferred group, 61% started antiretroviral therapy (median time to therapy 28 months, which was AZT monotherapy in 94%). During the first year of follow-up immediate AZT halved the rate of disease progression (P<0.0001), increasing the probability of AIDS-free survival at one year from 96% to 98%, but this early benefit did not persist: after 6 years AIDS-free survival was 54% in both groups, and at no time was there any difference in overall survival, which at 6 years was 64% with immediate and 65% with deferred AZT (rate ratio [RR] 1.04, 95% confidence interval [CI] 0. 94 to 1.15).

REVIEWER'S CONCLUSIONS

Although immediate use of AZT halved disease progression during the first year, this effect was not sustained, and there was no improvement in survival in the short or long term.

Surrogate markers in HIV disease

The use of surrogate markers in HIV disease is an attractive method of assessing the efficacy of new treatments more quickly than by using clinical end-points. The characteristics of an ideal surrogate marker and the theoretical dangers of extrapolating properties from one class of drug to another are described. These characteristics are compared with the use of the CD4 lymphocyte count, which so far has been the most widely studied. Results from 14 randomized controlled trials of nucleoside analogues are used to compare the comparative changes of CD4 counts with the differential rates of progression to AIDS and differences in survival. There was some correlation between CD4 count changes and development of AIDS, particularly in the short term trials. In contrast, there was little correlation between CD4 counts and overall survival. Comparative studies between clinical end-points and quantitative measures of plasma viraemia have not yet been completed. In conclusion, no surrogate marker has yet been shown to be useful in predicting the efficacy of anti-HIV treatment. Until surrogate markers are validated against the results from long term clinical trials, they should only be used to screen new drugs warranting further study rather than to draw conclusions on the clinical efficacy of new treatments.

Cognitive behaviour therapy for the chronic fatigue syndrome: a randomized controlled trial

OBJECTIVE

To evaluate the acceptability and efficacy of adding cognitive behaviour therapy to the medical care of patients presenting with the chronic fatigue syndrome.

DESIGN

Randomised controlled trial with final assessment at 12 months.

SETTING

An infectious diseases outpatient clinic.

SUBJECTS

60 consecutively referred patients meeting consensus criteria for the chronic fatigue syndrome.

INTERVENTIONS

Medical care comprised assessment, advice, and follow up in general practice. Patients who received cognitive behaviour therapy were offered 16 individual weekly sessions in addition to their medical care.

MAIN OUTCOME MEASURES

The proportions of patients (a) who achieved normal daily functioning (Karnofsky score 80 or more) and (b) who achieved a clinically significant improvement in functioning (change in Karnofsky score 10 points or more) by 12 months after randomisation.

RESULTS

Only two eligible patients refused to participate. All randomised patients completed treatment. An intention to treat analysis showed that 73% (22/30) of recipients of cognitive behaviour therapy achieved a satisfactory outcome as compared with 27% (8/30) of patients who were given only medical care (difference 47 percentage points; 95% confidence interval 24 to 69). Similar differences were observed in subsidiary outcome measures. The improvement in disability among patients given cognitive behaviour therapy continued after completion of therapy. Illness beliefs and coping behaviour previously associated with a poor outcome changed more with cognitive behaviour therapy than with medical care alone.

CONCLUSION

Adding cognitive behaviour therapy to the medical care of patients with the chronic fatigue syndrome is acceptable to patients and leads to a sustained reduction in functional impairment.

An eight year experience of conservative management for aortic graft sepsis

This paper describes the results of conservative management of 15 patients with aortic graft infection. The median time to presentation was 4 months. Six of eight grafts that were sent for culture grew organisms, of which the commonest were streptococci and coagulase negative staphylococci. Four patients did not receive intensive antibiotic treatment and all died of sepsis. Eleven patients received intensive intravenous and oral antibiotic therapy and appropriate surgical management; two of these died, one of a stroke and the other of an unknown cause. Two of the nine surviving patients had no surgery and the remainder had procedures to drain pus and unblock occluded grafts, including minimal graft excision in four patients, although two of these subsequently required total graft excision. The follow-up period for six of these nine patients is more than 4 years. For most patients with aortic graft infection aggressive antibiotic treatment supplemented by minimalist surgery is preferable to primary radical surgery.