Do skin prick and conjunctival provocation tests predict symptom severity in seasonal allergic rhinoconjunctivitis?

BACKGROUND: In the investigation of seasonal allergic rhinoconjunctivitis (SAR), quantitative skin and conjunctival allergen challenge tests are used to measure individual allergen sensitivity. These tests are reproducible and relate well to prevalence but their relationship to symptom severity is less well established. OBJECTIVE: We wished to determine if quantitative skin prick tests (QSPT) and conjunctival provocation tests (CPTs) using a single grass pollen allergen extract are reproducible and predict symptom severity in SAR. METHODS: We retrospectively analysed data from 91 participants in a previously published randomized placebo controlled study of low dosage allergen immunotherapy who were randomized to receive placebo treatment. We examined the relationship between pre-seasonal QSPT, CPT and SAR symptoms. RESULTS: We found a high level of reproducibility when repeated measures were compared for both the QSPT (P < 0.001) and the CPT (P < 0.001) and moderate correlation (0.49) between the standard skin prick test (SPT) and the QSPT (P < 0.001). We found weak negative correlation (-0.27) between the QSPT and the CPT (P < 0.001). We found no correlation between seasonal symptom, use of rescue medication or quality of life (QOL) scores and pre-seasonal QSPT or CPT. Conclusion In the assessment of seasonal rhinoconjunctivitis, quantitative skin and conjunctival allergen challenge tests are strongly reproducible, although there is no correlation between these tests and seasonal symptom, use of rescue medication or QOL scores.     

Promoting clinically effective practice: general practitioners' awareness of sources of research evidence

BACKGROUND: Practitioners are being encouraged to base their clinical practice on research evidence. In order to do this, they must be aware of and use the sources of evidence. METHODS: A questionnaire survey was undertaken to establish GPs' awareness of research evidence in their clinical practice and, in fundholding practices, its influence on purchasing plans. Questionnaires were sent to 360 lead fundholders in North Thames Region and 440 of a random sample of the remaining general practitioners in the region for comparison. RESULTS: Questionnaires were returned by 62% of lead fundholders and 63% of GPs in the random sample. There was limited use of the electronic sources of clinical effectiveness. There was greater reported awareness of published sources of research evidence and fundholding GPs were significantly more likely to have referred to publications summarizing research evidence. CONCLUSIONS: GPs seem to make more use of published clinical effectiveness sources than the electronic databases. Consequently, they need educational and technical support if they are to make full use of the available sources of research evidence available in other media.      

Variability of ankle and brachial systolic pressures in the measurement of atherosclerotic peripheral arterial disease.

The aim of this study was to determine the variability of measurements of ankle and brachial systolic pressures and ankle brachial ratios in order to assess their suitability for use in epidemiological studies of arterial disease in the lower limbs. Thirty-six subjects had repeat measurements taken by four observers on two separate days using a Doppler probe and random zero sphygmomanometer. The variability in the measurement of ankle systolic pressure was comparable to that for brachial systolic pressure. The 95% confidence limits of one measurement of the ankle brachial ratio was estimated to be +/- 16%, reducing to +/- 10% for the mean of four measurements taken by two observers on two days. Analysis of variance indicated that the variability in the measurement of ankle brachial ratios attributable to observers, days, timing of measurements on the same day, and repeat measurements was considerably less than the "biological" variability between subjects and between legs. These results suggest that repeatability of the ankle brachial ratio is such that a single measurement is suitable for most epidemiological studies of atherosclerotic peripheral arterial disease.     

Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability

X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene. Disease-associated alleles (37-66 CAGs) change in length when transmitted from parents to offspring, with a significantly greater tendency to shift size when inherited paternally. As transgenic mice carrying human AR cDNAs with 45 and 66 CAG repeats do not display repeat instability, we attempted to model trinucleotide repeat instability by generating transgenic mice with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions in their genomic context. Studies of independent lines of AR YAC transgenic mice with CAG 45 alleles reveal intergenerational instability at an overall rate of approximately 10%. We also find that the 45 CAG repeat tracts are significantly more unstable with maternal transmission and as the transmitting mother ages. Of all the CAG/CTG repeat transgenic mice produced to date the AR YAC CAG 45 mice are unstable with the smallest trinucleotide repeat mutations, suggesting that the length threshold for repeat instability in the mouse may be lowered by including the appropriate flanking human DNA sequences. By sequence-tagged site content analysis and long range mapping we determined that one unstable transgenic line has integrated an approximately 70 kb segment of the AR locus due to fragmentation of the AR YAC. Identification of the cis - acting elements that permit CAG tract instability and the trans -acting factors that modulate repeat instability in the AR YAC CAG 45 mice may provide insights into the molecular basis of trinucleotide repeat instability in humans.      

Hypersensitivity to airborne spitting cobra snake venom.

BACKGROUND: Although the cytolytic, neurotoxic, and hemolytic actions of snake venoms are well known, the ability of airborne inhaled snake venom of the spitting cobra to induce asthma in snake handlers has not been reported. OBJECTIVE: To report the allergenicity of inhaled snake venom in a snake handler who developed increasing hypersensitivity to airborne venom, produced by spitting cobras during public demonstrations. METHODS: Serum samples were obtained from 2 handlers (our study patient and another snake handler who reported developing wheezing when handling spitting cobras), and desiccated venom was obtained from 9 species to which the handlers were exposed. Serum from an asymptomatic and nonatopic snake handler exposed to the same snake species was used as a control. Phosphate-buffered saline extracts were prepared from the desiccated venom, proteins in the venom extracts were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblotting was performed. Inhibition enzyme-linked immunosorbent assays (ELISAs) were performed to demonstrate cross-reactivity. RESULTS: The study patient had never been previously bitten by a cobra. Wheezing occurred rapidly on inhalational exposure and was reversed by inhalation of salbutamol. The patient had developed IgE antibodies to 9 different snake venoms on Western immunoblots, with major IgE binding proteins of 59 to 63 kDa and 8 to 15 kDa. The cross-reactive nature of the IgE epitopes in the venoms in the different species was also confirmed by 50% inhibition of IgE binding in an ELISA by preincubation with unrelated species. Life-threatening sensitivity of the patient was sustained after a long period of avoidance. CONCLUSIONS: We propose that aerosolized snake venom be considered a new potential source of allergens that may result in anaphylaxis on subsequent exposure. Further studies of the development of specific IgE sensitization following snakebites and the risks of such sensitization should be conducted on snake handlers, particularly those who demonstrate the spitting species.     

Association of DLG5 R30Q variant with inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory diseases of the gastrointestinal system known as the inflammatory bowel diseases (IBD). Recently, Stoll and colleagues reported a novel finding of genetic variation in the DLG5 gene that is associated with IBD (CD and UC combined). We present here a study of the genetic variation described in that report in two well-powered, independent case-control cohorts and one family-based collection, and confirm the proposed association between IBD and the R30Q variant of DLG5 in two of the three studies. We are, however, unable to replicate the other proposed association to the common haplotype described in Stoll et al and suggest that this other finding could conceivably have been partially a statistical fluctuation and partially a result of LD with the replicated R30Q association. This study provides support for the hypothesis that DLG5 constitutes a true IBD risk factor of modest effect.     

Does fish oil supplementation in pregnancy reduce the risk of allergic disease in infants?

PURPOSE OF REVIEW: Parallel increases in many inflammatory diseases over the last 40 years suggest that common environmental changes are promoting inflammatory immune responses and/or inhibiting the processes that normally keep these in check. One key change during this period has been declining intakes of anti-inflammatory dietary factors, including omega-3 polyunsaturated fatty acids (n-3 PUFA). As allergic diseases often first manifest in early infancy, prevention strategies need to be targeted early, even in utero. This review will examine recent evidence for the use of fish oil during this early period as a primary prevention strategy for allergic disease. RECENT FINDINGS: N-3 PUFA have well documented anti-inflammatory effects in vitro and have also been demonstrated to have health benefits in a range of chronic inflammatory diseases, including cardiovascular disease, rheumatoid arthritis and diabetes, supporting their role in modulating inflammation in vivo. Although the effects of fish oil supplementation in established allergic disease are less convincing, there is accumulating evidence that dietary n-3 PUFA may have greater effects before allergic responses are established. SUMMARY: Supplementation of the maternal diet in pregnancy with n-3 PUFA may provide a non-invasive intervention with significant potential to prevent the development of allergic and possibly other immune-mediated diseases.     

Constitutive macropinocytosis allows TAP-dependent major histocompatibility compex class I presentation of exogenous soluble antigen by bone marrow-derived dendritic cells

Dendritic cells expanded from mouse bone marrow (BMDC) with granulocyte/macrophage-colony-stimulating factor have potent T cell-stimulatory properties both in vitro and in vivo. This has been well documented for major histocompatibility complex (MHC) class II-restricted responses, and more recently using peptide-loaded and protein-pulsed DC for CD8 responses following adoptive transfer in mice. An unresolved question concerns the capacity of BMDC to present exogenous antigen on MHC class I molecules, an unconventional mode of MHC class I loading for which there is now considerable evidence, particularly in macrophages. Here, we show that BMDC exhibit high levels of macropinocytosis driven by constitutive membrane ruffling activity. Up to one-third of actively ruffling and macropinocytosing BMDC transferred pinocytosed horseradish peroxidase into the cytosol following a 15-min pulse, suggesting that they might be capable of presenting exogenous soluble antigen on MHC class I molecules. We show that BMDC presented exogenous ovalbumin to a T cell hybridoma more effectively, more rapidly, and at lower exogenous antigen concentrations than BM macrophages on a cell-for-cell basis. Presentation was TAP dependent, brefeldin A sensitive, and blocked by inhibitors of proteasomal processing, demonstrating use of the classical MHC class I pathway. Although effective presentation of exogenous antigen by BMDC occurred in the absence of agents which stimulate macropinocytosis, treatment with phorbol myristate acetate (PMA) enhanced both pinocytosis and MHC class I presentation by BMDC. Finally, PMA-stimulated BMDC exposed to exogenous ovalbumin in vitro were able to prime an antigen-specific cytotoxic T lymphocyte response following adoptive transfer in vivo.     

Immunization with Pseudomonas aeruginosa high-molecular-weight polysaccharides prevents death from Pseudomonas burn infections in mice.

High-molecular-weight polysaccharides from the extracellular slime of Pseudomonas aeruginosa were evaluated as immunogens in Pseudomonas burn infections in mice. Immunization with immunotype 1 or 2 polysaccharides induced a strong immunotype-specific and weak cross-reactive antibody response but protected mice against burn infections caused by either immunotype. Passive protection was provided by rabbit antiserum to immunotype 1 polysaccharide against burn infection by the homologous organism. Pseudomonas high-molecular-weight polysaccharides are potentially effective vaccines in burn infections.     

Different Chinese hamster cell lines express a G1 period for different reasons

Previous studies from our laboratory have shown that the absence of G1 (G1^– condition) in two lines of Chinese hamster cells is dominant over the presence of G1 (G1⁺ condition) in a variety of intraspecific cell hybrids. G1⁺ mutants or variants can be isolated from G1^– cells following mutagenesis and selection. These G1⁺ mutants fall into multiple complementation groups based on their abilities to form G1^– cell hybrids with one another. This is evidence that different mutants have G1 intervals for different reasons, possibly as the result of deficiencies in functions necessary for G1^– cell cycles. In this report we have used cell hybrid analysis to ask whether cells of different, naturally occurring G1⁺ lines of Chinese hamster are able to complement to produce G1^– hybrids. We have found three complementation groups among the four G1⁺ cell lines examined. Therefore, these lines define three different reasons or bases for the existence of a G1 interval. These results lead us to suggest that multiple requirements must be met for these cells to start the S period, but that failure to fulfill only a single and different requirement is responsible for the presence of a G1 interval in any given cell line.