A case for revising the strength of the relationship between childhood asthma and atopy in the developing world

Introduction. Asthma is the commonest chronic condition of children. Diagnosis remains difficult and many surrogate markers are used, such as documenting evidence of atopy.Method. Two studies investigated the role of atopy in childhood asthma. The first documented the prevalence and nature of allergy sensitivities in a group of asthmatic children compared with non-asthmatic children in Pretoria, South Africa. The second enrolled a random sample of asthmatic children and their mothers attending the Children’s Chest and Allergy Clinic at Steve Biko Academic Hospital, Pretoria. Children were classified as having atopic or non-atopic asthma. Mothers completed a questionnaire to reveal atopic features.Results. In the first study, only 45.0% of asthmatic children had a positive skin-prick test (SPT), as opposed to 16.2% of control children. This is a lower proportion than in many reported international studies. In the second study, 64 children with atopic asthma and 36 with non-atopic asthma were studied, along with their mothers. The proportion of children with atopic asthma did not differ for mothers with and without a positive SPT  (p=0.836), a history of asthma (p=0.045) or symptoms suggestive of an allergic disease (p=1.000), or who were considered to be allergic  (p=0.806). The odds ratio (OR) of a child having atopic asthma when he or she had a mother with a doctordiagnosed history of asthma was 4.76, but the sensitivity was low (21.9%).Conclusion. The data demonstrate that fewer asthmatic children in South Africa are atopic than was previously thought. Also, all maternal allergic or asthmatic associations are poor predictors of childhood atopic asthma.  Despite the increased risk of atopic asthma in a child of a mother who has a doctor diagnosis of asthma (OR 4.76; p=0.045), this is a poor predictor of atopic asthma (sensitivity 21.9%)

Prevalence of Blomia tropicalis allergy in two regions of South Africa

Background. Asthma and allergic rhinitis affect 15% and 38% of South African (SA) children, respectively. The housedust mite (HDM) is the most significant indoor aeroallergen. Typical HDM species include Dermatophagoides pteronyssinus, D. farinae and Blomia tropicalis. Conventional skin-prick testing (SPT) panels only test for Dermatophagoides. B. tropicalis has been described in the tropical and subtropical regions, but is not routinely tested for in SA.Objective. To ascertain the significance of B. tropicalis as an aeroallergen in northern coastal KwaZulu-Natal Province (KZN), a tropical environment, and in Johannesburg in the highveld, where the climate is milder and less humid.Methods. Children aged 1 - 18 years with features of allergic rhinitis and/or asthma were recruited over a 6-month period from Alberlito Hospital in northern KZN and the Clinton Clinic in Johannesburg. SPTs included Dermatophagoides and B. tropicalis. Sensitisation was defined as a wheal 3 mm greater than the negative control.Results. Eighty-five subjects were included, 50 in northern KZN and 35 in the Johannesburg arm; 52% of subjects in northern KZN and 3% in Johannesburg were sensitised to B. tropicalis, with a significant difference between these centres (p<0.05). Of the 52% sensitised to B. tropicalis in northern KZN, half were sensitised only to B. tropicalis.Conclusion. There is a high prevalence of B. tropicalis allergy in the tropical northern KZN region and a much lower prevalence in the Johannesburg region. Routine testing for B. tropicalis allergy should be employed in northern KZN

A large radio nebula around P Cygni

We present a large set of radio observations of the luminous blue variable P Cygni. These include two 6-cm images obtained with MERLIN which spatially resolve the 6-cm photosphere, monitoring observations obtained at Jodrell Bank every few days over a period of two months, and VLA observations obtained every month for seven years. This combination of data shows that the circumstellar environment of P Cyg is highly inhomogeneous, that there is a radio nebula extending to almost an arcminute from the star at 2 and 6 cm, and that the radio emission is variable on a time-scale no longer than one month, and probably as short as a few days. This short-time-scale variability is difficult to explain. We present a model for the radio emission with which we demonstrate that the star has probably been losing mass at a significant rate for at least a few thousand years, and that it has undergone at least two major outbursts of increased mass loss during the past two millenia

Atopy in HIV-infected children in Pretoria

Introduction. The development or aggravation of a pre-existingatopic state in patients with human immunodeficiency virus(HIV) has not been thoroughly investigated in South Africa.HIV-infected adults have been shown to have a higherprevalence of atopy in some international studies, but this hasnot been documented in children.Methods. A prospective convenience sample of 50 childrenaged between 3 months and 12 years attending the TshwaneDistrict Hospital Paediatric HIV clinic in Pretoria wasrecruited. Their personal and family histories of atopy, WorldHealth Organization (WHO) HIV clinical staging and Centersfor Disease Control (CDC) immunological staging with CD4counts were documented. An age- and sex-matched controlgroup of 50 HIV-negative children was included. Skin pricktests (SPTs) to identify common aeroallergens were conductedon all patients.Results. One hundred children were enrolled, with 50 in eachgroup. Ten per cent of the HIV-infected patients comparedwith 16% of controls had positive SPTs to aeroallergens. Ahigher percentage of the HIV-infected patients had chronicrhinitis and eczema (60% and 68%, respectively). Therewas no relationship between CD4 count and positive SPTs(p=0.61), mean log CD4 count and presence of reportedasthma (p=0.71), and CD4 count and presence of reporteddermatitis (p=0.84). The CD4 count was not statisticallydifferent between children with and without a family historyof atopy (p=0.68).Conclusion. It appears that the stage of HIV disease does notinfluence the development or expression of allergy. There is a high prevalence of dermatitis and chronic rhinitis in HIVinfectedchildren, probably not atopic in origin

Diversity of gut microflora is required for the generation of B cell with regulatory properties in a skin graft model

B cells have been reported to promote graft rejection through alloantibody production. However, there is growing evidence that B cells can contribute to the maintenance of tolerance. Here, we used a mouse model of MHC-class I mismatched skin transplantation to investigate the contribution of B cells to graft survival. We demonstrate that adoptive transfer of B cells prolongs skin graft survival but only when the B cells were isolated from mice housed in low sterility "conventional" (CV) facilities and not from mice housed in pathogen free facilities (SPF). However, prolongation of skin graft survival was lost when B cells were isolated from IL-10 deficient mice housed in CV facilities. The suppressive function of B cells isolated from mice housed in CV facilities correlated with an anti-inflammatory environment and with the presence of a different gut microflora compared to mice maintained in SPF facilities. Treatment of mice in the CV facility with antibiotics abrogated the regulatory capacity of B cells. Finally, we identified transitional B cells isolated from CV facilities as possessing the regulatory function. These findings demonstrate that B cells, and in particular transitional B cells, can promote prolongation of graft survival, a function dependent on licensing by gut microflora

Intermittent dislocation flow in viscoplastic deformation

The viscoplastic deformation (creep) of crystalline materials under constant stress involves the motion of a large number of interacting dislocations. Analytical methods and sophisticated `dislocation-dynamics' simulations have proved very effective in the study of dislocation patterning, and have led to macroscopic constitutive laws of plastic deformation. Yet, a statistical analysis of the dynamics of an assembly of interacting dislocations has not hitherto been performed. Here we report acoustic emission measurements on stressed ice single crystals, the results of which indicate that dislocations move in a scale-free intermittent fashion. This result is confirmed by numerical simulations of a model of interacting dislocations that successfully reproduces the main features of the experiment. We find that dislocations generate a slowly evolving configuration landscape which coexists with rapid collective rearrangements. These rearrangements involve a comparatively small fraction of the dislocations and lead to an intermittent behavior of the net plastic response. This basic dynamical picture appears to be a generic feature in the deformation of many other materials. Moreover, it should provide a framework for discussing fundamental aspects of plasticity, that goes beyond standard mean-field approaches that see plastic deformation as a smooth laminar flow

Emergency ambulance service involvement with residential care homes in the support of older people with dementia : an observational study

© 2014 Amador et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.BACKGROUND: Older people resident in care homes have a limited life expectancy and approximately two-thirds have limited mental capacity. Despite initiatives to reduce unplanned hospital admissions for this population, little is known about the involvement of emergency services in supporting residents in these settings.METHODS: This paper reports on a longitudinal study that tracked the involvement of emergency ambulance personnel in the support of older people with dementia, resident in care homes with no on-site nursing providing personal care only. 133 residents with dementia across 6 care homes in the East of England were tracked for a year. The paper examines the frequency and reasons for emergency ambulance call-outs, outcomes and factors associated with emergency ambulance service use. RESULTS: 56% of residents used ambulance services. Less than half (43%) of all call-outs resulted in an unscheduled admission to hospital. In addition to trauma following a following a fall in the home, results suggest that at least a reasonable proportion of ambulance contacts are for ambulatory care sensitive conditions. An emergency ambulance is not likely to be called for older rather than younger residents or for women more than men. Length of residence does not influence use of emergency ambulance services among older people with dementia. Contact with primary care services and admission route into the care home were both significantly associated with emergency ambulance service use. The odds of using emergency ambulance services for residents admitted from a relative's home were 90% lower than the odds of using emergency ambulance services for residents admitted from their own home. CONCLUSIONS: Emergency service involvement with this vulnerable population merits further examination. Future research on emergency ambulance service use by older people with dementia in care homes, should account for important contextual factors, namely, presence or absence of on-site nursing, GP involvement, and access to residents' family, alongside resident health characteristics.Peer reviewedFinal Published versio

Health and lifestyle of Nepalese migrants in the UK

Background: The health status and lifestyle of migrants is often poorer than that of the general population of their host countries. The Nepalese represent a relatively small, but growing, immigrant community in the UK, about whom very little is known in term of public health. Therefore, our study examined the health and lifestyle of Nepalese migrants in the UK. Methods: A cross-sectional survey of Nepalese migrants in UK was conducted in early 2007 using a postal, self-administered questionnaire in England and Scotland (n = 312), and telephone interviews in Wales (n = 15). The total response rate was 68% (327 out of 480). Data were analyzed to establish whether there are associations between socio-economic and lifestyle factors. A multivariate binary logistic regression was applied to find out independent effect of personal factors on health status. Results: The majority of respondents was male (75%), aged between 30 and 45 (66%), married or had a civil partner (83%), had university education (47%) and an annual family income (69%) ranging from £5,035 to £33,300. More than one third (39%) of the respondents have lived in the UK for 1 to 5 years and approximately half (46%) were longer-term residents. Most (95%) were registered with a family doctor, but only 38% with a dentist. A low proportion (14%) of respondents smoked but more than half (61%) consumed alcohol. More than half (57%) did not do regular exercises and nearly one fourth (23%) of respondents rated their health as poor. Self reported 'good' health status of the respondents was independently associated with immigration status and doing regular exercise Conclusion: The self reported health status and lifestyle, health seeking behaviour of Nepalese people who are residing in UK appears to be good. However, the overall regular exercise and dentist registration was rather poor. Health promotion, especially aimed at Nepalese migrants could help encourage them to exercise regularly and assist them to register with a dentist