PubMed Health⌕ Search

Biomedical subjects

T G Merrett

Publications and source records attributed to T G Merrett.

At least 19 recordsLinked to original sources
PubMed1992

House dust mite sensitivity: interaction of genetics and allergen dosage.

Pairwise analysis of siblings from 21 families showed that house dust mite (HDM) sensitive children were exposed to higher concentrations of Der p I allergen in their mattress (P = 0.005) and bedding (P = 0.04), but not bedroom floor (P = 0.33), than their atopic sibling who was not sensitive to HDM antigens. There was no difference in the exposure to HDM numbers/100 mg of dust in the mattress (P = 0.61) or bedroom floors (P = 0.09). In contrast, pairwise analysis of siblings from 15 families showed that HDM sensitive children were not exposed to significantly different concentrations of Der p I in the mattress (P = 0.96), bedding (P = 0.11) or bedroom floor (P = 0.70) nor HDM numbers/100 mg of dust in the mattress (P = 0.12) and bedroom floor (P = 0.98) than their non-atopic siblings. These findings were identical when absolute allergen load was compared in these pairs. Genetic linkage studies in these families suggest the tendency to atopic IgE responses is conferred by a putative atopy locus on chromosome 11q. These results together suggest that differences in allergen levels in beds, among siblings with a comparable genetic tendency to atopy, play a significant role in determining the development of HDM allergy.

Allergens↗
PubMed1991

Effectiveness of an acaricide in management of house dust mite allergy.

The effects of treating the environment of 25 dust mite-allergic patients with an acaracide are reported. Remarkable symptomatic improvements in asthma, eczema, or rhinitis were observed. Many patients could reduce or stop medication, and these benefits have persisted for up to a year after using Acarosan once only. Relapse of symptoms following exposure to untreated dusty environments was observed on many occasions confirming that the improvements were due to removal of the mite allergen.

Adolescent↗
PubMed1979

The radioallergosorbent test (RAST) in nasal polyposis.

The incidence of atopy among 64 adults undergoing polypectomy was 25 per cent. Among these atopic patients it was usual for the polyp IgE level to exceed that in the serum. Similarly, D. pteronyssinus-specific IgE was more commonly identified in polyp fluid by the RAST technique than in serum. However, this was not so for grass pollen-specific IgE, where serum and polyp fluid were equally positive. We conclude that there are atopic and non-atopic polyps.

Adult↗
PubMed1979

Epithelial or dandruff allergen for the diagnosis of dog allergy by RAST?

When used for screening by the RAST technique, dog epithelium provided too few positive results (29.2%) compared with dog dandruff (58.8%), cat epithelium (53.6%) and horse dandruff (52.2%). However, dog dandruff can provide an unexpectedly high incidence of positive RAST results (45.2%) in sera from patients with an allergic history to cat or horse, but not to dog. Dog dandruff allergens were found to cross-react with some cat or horse serum proteins in about 25% of such patients. We conclude that dog dandruff is preferable to epithelium for screening by the RAST technique, but if emotional issues involving a family pet arise then confirmation by a trial separation is likely to be more convincing than a provocation test with a possibly non-specific allergenic extract.

Allergens↗
PubMed1978

Methods of quantifying circulating IgE.

Four radioimmunoassay techniques, two conventional and two sandwich, have been used to measure circulating IgE levels in 100 sera. The test sera had IgE levels ranging from 1.0 to 20,000 u/ml, and each was measured at five dilutions, ranging from three-fold to 400-fold. The same IgE standards were used throughout, and the optimal range for each assay was determined by assessing data for quality control sera and the WHO standard 69/204. To be of general use in the United Kingdom an IgE test must measure accurately levels as low as 20-30 u IgE/ml. The Phadebas RIST method failed to meet this criterion, and of the remaining tests the double antibody method had the most useful operating range and produced the most reliable results. However, the double antibody method is not available commercially and so, for the majority of laboratories, the Phadebas PRIST technique should be the method chosen.

Animals↗
PubMed1978

Computer analysis of allergic histories taken by questionnaire.

We report the development of a detailed allergy questionnaire designed so that the answers can be typed into a mini-computer. Computer programmes have been written to file and to retrieve these answers, and to print a summary which is then 'weighed', so as to produce a clinical atopy score which is then further broken down into indoor and outdoor scores. In a pilot survey of ninety patients, their clinical atopy scores and immunoglobulin E (IgE) profiles have been compared, and additional computer programmes have been written which will (a) assess if a more detailed IgE investigations is warranted, and (b) suggest which allergens, if any, are likely to be responsible for the patients' symptoms.

Adult↗
PubMed1978

RAST atopy screen.

A single in vitro screening test for atopic allergy is described. It uses the radioallergosorbent test (RAST) principle, and has been applied to screening sera from U.K. patients with possible atopic symptoms. When compared with the Phadebas RAST, the test sensitivity was 97% and the specificity 100%, and these results suggest that it is useful in any preliminary allergy investigation.

Animals↗
PubMed1977

Prognostic value of serum levels of immunoglobulins (IgG, IgA, IgM and IgE) in breast cancer: a preliminary study.

One hundred and sixty women admitted for breast tumour biopsy to the King's College Hospital group have been followed sequentially for 2 years. Sixty-nine women had early operable breast cancer and 91 had benign breast disease. All these women had serum immunoglobulin IgG, IgA, IgM and IgE levels measured preoperatively and postoperatively at 3 months, 1 year and 2 years. No differences were found in any of the serum immunoglobulin levels between the two groups at any time. There was, however, a positive correlation between the extent of metastatic breast cancer and the serum level of various immunoglobulins, particularly IgA. There was no evidence that routine postoperative radiotherapy influenced the levels of serum immunoglobulins. The findings suggest a secondary defence reaction against increasing tumour load, and do not support the theory of an early immune defect in immunoglobulin metabolism which could play a part in the pathogenesis of breast cancer. Although there is no diagnostic value in measuring the levels of serum immunoglobulins in patients with breast tumours, there may be some value in following the levels in cancer patients, as a guide to subclinical spread of the disease.

Aged↗
PubMed1977

IgE, parasites and asthma in Tanzanian children.

Two rural Tanzanian primary schools were surveyed to test the hypothesis that parasitic infestation prevents the development of asthma. 242 pupils were interviewed to determine the prevalence of pupils with recurrent episodes of wheezing. The nineteen pupils so discovered had more exercise-induced bronchial lability than equivalently exercised controls. More girls (12.8%) than boys (3.3%) had asthma. In one school, 77% of the controls had faecal parasites, mainly Ascaris spp., and in the other school 55% of the controls had Schistosoma haematobium in their urine. Parasites were found in similar proportions in the asthmatics. The mean serum IgE for the whole population was 3174 u/ml with no demonstrable difference between the asthmatics and controls. There was no difference in immediate cutaneous hypersensitivity to twenty-two allergens between the asthmatics and controls. These findings suggest that parasitic infestation does not prevent the development of asthma.

Adolescent↗
PubMed1976

Measurement of specific IgE antibodies in nasal secretion--evidence for local production.

Serum levels of total and specific immunoglobulin E (IgE) have been determined by radioimmunoassays in sixty-nine allergic subjects. The forty-one subjects with mild symptoms were the most difficult to diagnose, since nine had IgE levels less than 50 U/ml and nineteen had no detectable specific IgE antibodies. Samples of nasal secretions were collected from these nineteen subjects and five were found to have specific IgE antibodies, and in a further eight increased amounts of total IgE. The possibility of locally produced IgE antibodies should therefore be considered when using in vitro tests to diagnose mild or recently acquired allergies, especially when serum IgE levels are less than 50 U/ml.

Humans↗
PubMed1976

Allergy and parasites: the measurement of total and specific IgE levels in urban and rural communities in Rhodesia.

Eighty adult asthmatics living in an African city had a significantly higher serum IgE level (799 u/ml) than the control group (350 u/ml). A high proportion (78.7%) of the asthmatics had demonstrable circulating mite-specific IgE antibodies. The rural population of a filariasis endemic region was investigated and although no allergic subjects were identified, the group had a significantly higher IgE level (1613 u/ml) than the asthmatics and also showed a relatively high incidence of grass pollen-specific IgE antibodies (35%). The discrepancy between clinical history and laboratory results supports the mast cell saturation hypothesis and suggests: (a) an explanation for the susceptibility to allergy of African and Asian immigrants to Great Britain, and (b) a practical approach for preventing allergic reactions in vivo.

Adolescent↗
PubMed1976

Identification of allergen-specific IgE antibodies in the sera of African asthmatics.

Of eighty African asthmatics, sixty-three had significant levels of specific IgE against the house dust mite dermatophagoides pteronyssinus. By contrast, grass-specific IgE was found in six patients and mould-specific IgE in none. Sixty-three patients also had symptoms predominantly during the rainy season. Positive skin tests against D. pteronyssinus correlated well with the presence of mite-specific IgE, as did the size of these skin test weals with the amount of specific IgE. For grass pollen and moulds there was no such relationship. There was no correlation between a history of sensitivity to house dust and either skin tests or specific IgE against D. pteronyssinus. The results support previous findings that it is allergy to house dust mite and not to grass pollens or moulds which is important in producing the seasonal symptoms in our patients.

Adult↗
PubMed1975

A detailed investigation of circulating IgE levels in a normal population.

Total circulating IgE levels were measured in a carefully selected normal population, using a highly sensitive double antibody assay. The mean level of 36.3 u/ml found in this group is much lower than that reported in all previous studies. No circadian rhythm was evident, but IgE levels varied slightly from day-to-day. IgE levels in 100 serum samples were compared using the double antibody assay and the Phadebas test kit, based on a solid phase technique. A poor correlation was obtained with values below 100 u/ml, however, there was an excellent correlation for samples with IgE levels above this figure.

Adolescent↗