Biomedical subjects

J Longbottom

Publications and source records attributed to J Longbottom.

5 recordsLinked to original sources

PubMed1989

Complex microphthalmos.

Forty patients were diagnosed as having complex microphthalmos on the basis of a malformed globe with a total axial length measurement at least 2 SDs below the mean for age-similar controls. Three had anterior segment dysgenesis; 4, congenital lens abnormalities; 14, chorioretinal colobomas; 12, persistent hyperplastic primary vitreous; 4, retinal dysplasia; and 3, complex malformations due to ipsilateral facial malformations. Measurements of total axial length indicated that complex microphthalmos was congenital and that postnatal growth of the malformed eye was similar to that of normal eyes. In most patients the anterior segment length was normal, while in all patients the posterior segment length was at least 2 SDs below the mean. Corneal diameter correlated significantly with total axial length (r2 = .57) and decreased linearly as total axial length decreased. In most patients in whom measurements were obtained, the lens and corneal power were increased, thereby compensating for decreased total axial length. We propose that inadequate production of secondary vitreous is the cause of the microphthalmos, given that the posterior segment was disproportionately reduced in size and the secondary vitreous is its predominant component. Evidence that each of the various ocular malformations can influence the production of secondary vitreous is presented.

Abnormalities, Multiple↗

PubMed1989

Simple microphthalmos.

Simple microphthalmos was diagnosed in 22 patients on the basis of a normal-appearing eye and a total axial length at least 2 SDs below the mean for age. Anterior segment length was normal in most patients while posterior segment length was at least 2 SDs below the mean in all patients, indicating that disproportionate reduction in posterior segment length accounted for the microphthalmos. The normal values for total axial length, anterior segment length, and posterior segment length were determined from the analysis of axial length measurements obtained from age-similar controls. Ten patients had isolated microphthalmos. One of them was diagnosed as having nanophthalmos on the basis of microcornea, total axial length less than 18 mm, and absence of systemic disease. Twelve patients had associated systemic disorders, such as fetal alcohol syndrome, myotonic dystrophy, and achondroplasia, which implicated decreased size of the optic cup, altered vitreous proteoglycans, low intraocular pressure, and abnormal release of growth factors in the pathogenesis of microphthalmos.

Adult↗

PubMed1987

Occupational asthma and rhinitis related to laboratory rats: serum IgG and IgE antibodies to the rat urinary allergen.

Allergic reactions to rat urinary proteins are an important cause of occupational asthma and rhinitis among laboratory workers. We have measured IgG and IgE antibodies to a purified rat urinary allergen in sera from 179 laboratory workers of whom 30 reported symptoms on exposure to rats. There was a very good correlation between IgE antibodies and positive skin tests. In addition, there was a close correlation between reported asthmatic reactions and serum IgE antibody to rat allergen: IgE ab was present in 12/18 of workers with asthmatic reactions but in only 2/135 of workers without symptoms (p less than 0.001). Serum IgG antibodies to rat allergen were present in all sera with IgE antibody but were also present in 30% of asymptomatic individuals. The incidence and quantity of IgG antibody correlated with the degree of exposure to animals (i.e., hours per day) but not with the length of exposure in years. Our results on rat allergy confirm that there is an increased incidence of asthma among individuals who were atopic as judged by positive skin tests to other allergens. However, this relationship did not apply to individuals with rhinitis alone, and excluding atopic individuals from employment would have been a very inefficient method of reducing asthma or rhinitis in this group. Our results confirm that IgE antibody responses to rat urinary allergen are an important cause of occupational disease. The results for IgG antibody suggest that their prevalence represents a marker for the degree of exposure to rat proteins.

Animals↗

PubMed1977

Studies in chronic allergic bronchopulmonary aspergillosis. 3. Immunological findings.

Precipitin tests by two different methods, double-diffusion (DD) and counterimmunoelectrophoresis (CIE), and measurements of total and specific IgE against Aspergillus fumigatus were made in 50 patients with chronic allergic bronchopulmonary aspergillosis and in three control groups--atopics with a positive immediate prick test to A. fumigatus but no evidence of allergic aspergillosis, atopics with a negative prick test to A. fumigatus, and non-atopics. Precipitins were found in 84% and 78% of the patients with aspergillosis by the DD and CIE methods respectively. Precipitins were also found in 6 out of 27 (22%) patients with a positive prick test to A. fumigatus but no evidence of aspergillosis and in 1 of 24 patients with a negative prick test to A. fumigatus. The means of specific and total IgE values were significantly higher in the group of patients with aspergillosis than in the three other groups of patients. The increase in specific but not total IgE showed a statistically significant correlation with positive precipitin tests in the patients with aspergillosis. Total IgE but not specific IgE values were significantly higher (0-02 less than P less than 0-05) in patients who had had a transient radiographic shadow in the previous three months. Positive precipitin tests were also significantly correlated with the number of transient shadows in the past and with the interval of time since the last transient shadow.

Aspergillosis↗

PubMedDate not supplied

Asthma and rhinitis related to laboratory rats: use of a purified rat urinary allergen to study exposure in laboratories and the human immune response.

Using the major rat allergen as a model has made it possible to study both natural exposure and the human immune response to an important laboratory animal. The close correlation between positive skin tests to whole rat urine and IgE antibody to the major urinary allergen in this and previous studies supports the use of this protein as a model rat allergen. Measurements of airborne rat allergen confirm that the maximum levels are higher than those reported with pollen or mite allergens. However, it is possible that exposure to rat allergens is comparable to levels of exposure to cat salivary allergens in houses with cats. The clear implication is that the high levels of exposure are responsible for the fact that a large proportion of exposed individuals develop IgG antibodies. Our results suggest that the prevalence of IgG antibodies (not individual levels) in a group of workers would be a good guide to exposure. This leaves unresolved why some of the individuals who develop IgG ab also develop IgE ab and become at risk for developing asthmatic responses. Only part of this risk is related to atopy. A striking feature of all the studies on animal allergy is the close association between IgE ab and asthma. It appears clear that it is those immune responses that include IgE ab that are a risk factor for asthma. It is not sensible for anyone to remain consistently sick with asthma and continue working with laboratory animals because there are well documented examples of occupational asthma that has not resolved after ceasing exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗