Low prevalence of atopy in young Danish farmers and farming students born and raised on a farm.

BACKGROUND: Recent studies have shown that in several countries atopic sensitization to common allergens (common atopy) and atopic symptoms are markedly less prevalent in children living on a farm, compared with non-farm children living in the same rural areas. Living conditions on farms may, however, vary largely between different countries. It is also not yet known whether the "protective" effect of a farm environment can also be found in adults. MATERIALS AND METHODS: Common atopy and respiratory health were assessed by skin prick tests (SPT), questionnaire and measurement of bronchial hyper-responsiveness (BHR) in the Sund Stald (SUS) study, a cohort study on respiratory health in Danish farming students and conscripts from the same rural areas as controls. Results of SPT were confirmed by IgE serology in all SPT+ subjects and a subset of SPT- subjects. Prevalences of common atopy, respiratory symptoms and bronchial hyper- responsiveness were compared for farmers and controls, and for those who had or had not lived on a farm in early childhood. RESULTS: In multiple logistic regression analyses adjusting for ever smoking and a familial history of allergy, both being a farmer (ORs 0.62-0.75) and having had a farm childhood (ORs 0.55-0.75) appeared to contribute independently to a lower risk of sensitization to common allergens as assessed by SPT and IgE serology. A farm childhood was also inversely associated with high total IgE (OR 0.68), presence of respiratory symptoms (ORs 0.69-0.79) and BHR (OR 0.61) in these analyses. Direction and strength of the association between being a farmer and respiratory symptoms or BHR varied widely (ORs 0.69-1.28). CONCLUSION: The "anti-atopy" protective effect of a farm childhood could be confirmed in Danish farming students: prevalences of positive SPT, specific and total IgE, allergic symptoms and BHR were lower in those being born or raised on a farm. Past exposure to the farm environment in early childhood may therefore also contribute to a lower risk of atopic sensitization and disease at a later age.

S and Z alpha1-antitrypsin alleles are risk factors for bronchial hyperresponsiveness in young farmers: an example of gene/environment interaction.

Several studies have found an association between the rare Pi-alleles and asthma or bronchial hyperresponsiveness (BHR). This study deals with the effect of Pi-type on BHR among 2,308 young Danish people living in rural areas with a mean +/- SD age of 19.7+/-2.4 yrs. Interviews, pulmonary function testing, bronchial histamine provocation and skin-prick tests were performed. Serum alpha1-antitrypsin levels were determined and phenotyping was performed by means of isoelectric focusing and the subjects categorized into four groups: 1) MM and MX; 2) MS; 3) MZ; and 4) rare, i.e. SZ, SS and ZZ. Among the farmers, a significant positive trend for sensitization towards house dust mites was found, ranging from 12% in the MM group to 22% in the rare Pi-group. A positive test for trend was found within the Pi-groups in a one-sided test for doctor-diagnosed asthma with a peak prevalence of 40% for these symptoms among smokers in the rare Pi-group. On multiple logistic regression analysis, an increased odds ratio (OR) for BHR was found among farming school attendants with the rare Pi-alleles. The OR (95% confidence interval) was 1.71 (0.84-3.49) for MS, 1.93 (1.10-3.39) for MZ and 4.34 (1.19-15.8) for the rare Pi-group. Such a relationship was not found among the conscripts. These results show that a gene/environment interaction may exist between the farming occupation and the rare Pi-alleles, leading to a higher proportion of bronchial hyperresponsiveness related to the rare Pi-alleles in farming school attendants, in contrast to what is found among other young people living in rural areas.

Construction and characterization of an oxalic acid nonproducing strain of Aspergillus niger.

Aspergillus niger produces oxalic acid as a by-product which causes problems with downstream processing of industrial enzymes. To overcome this problem the oah gene encoding oxaloacetate hydrolase (EC 3.7.1.1) was disrupted in a glucoamylase-producing strain of A. niger and the resulting strain was incapable of producing oxalic acid. The strain with the disrupted gene was compared with the wild-type strain producing oxalic acid in batch cultivations. The specific growth rate of both strains was 0.20 h(-1). The citric acid yields were identical, but the glucoamylase yield was only 50% in the disruptant compared with the wild-type strain. Batch experiments with 13C-labeled glucose as substrate were carried out to determine the metabolic fluxes through the central metabolism. The two strains had almost identical metabolic fluxes, which suggested that it was possible to disrupt the oah gene without pleiotropic consequences. The flux through the pentose phosphate pathway was around 60% of the glucose uptake for both strains, which suggested that a sufficient supply of NADPH was available for biosynthesis.

Cloning and characterization of oah, the gene encoding oxaloacetate hydrolase in Aspergillus niger.

The enzyme oxaloacetate hydrolase (EC 3.7.1.1), which is involved in oxalate formation, was purified from Aspergillus niger. The native enzyme has a molecular mass of 360-440 kDa, and the denatured enzyme has a molecular mass of 39 kDa, as determined by gel electrophoresis. Enzyme activity is maximal at pH 7.0 and 45 degrees C. The fraction containing the enzyme activity contained at least five proteins. The N-terminal amino acid sequences of four of these proteins were determined. The amino acid sequences were aligned with EST sequences from A. niger, and an EST sequence that showed 100% identity to all four sequences was identified. Using this EST sequence the gene encoding oxaloacetate hydrolase (oah) was cloned by inverse PCR. It consists of an ORF of 1227 bp with two introns of 92 and 112 bp, respectively. The gene encodes a protein of 341 amino acids with a molecular mass of 37 kDa. Under the growth conditions tested, the highest oah expression was found for growth on acetate as carbon source. The gene was expressed only at pH values higher than 4.0.

Lung status in young Danish rurals: the effect of farming exposure on asthma-like symptoms and lung function.

The aim of this study was to assess the prevalence of asthma (self-reported) and relate this to lung function and factors associated with asthma in young farmers. Two hundred and ten female and 1,691 male farming students together with 407 males controls were studied. Each subject underwent a medical interview; forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were recorded using a dry wedge spirometer. Histamine bronchial reactivity was measured using the Yan method. Skin prick testing was performed using inhalant allergens. Nonsmokers had lower prevalence of asthma (5.4-10.8%) than smokers (11.3-21.0%) (p<0.05). Females reported symptoms of asthma nearly twice as often as males. Sex, smoking and a family history of asthma/allergy were significantly associated with asthma. Controls had higher standardized FEV1 and FVC residuals than male students, both nonsmokers (0.21 and 0.24) versus (-0.06 and -0.05) and smokers (0.29 and 0.33) versus (-0.11 and 0.13) (p<0.032). Bronchial hyperresponsiveness, asthma, siblings with allergy and working with cattle (controls only) were significantly associated with reduced lung function. In conclusion, the prevalence of asthma was significantly related to smoking, female sex, family history of asthma and allergy. Whilst bronchial hyperresponsiveness was associated with reduced lung function and lung function was slightly reduced in the male farming students, there was no association found between occupational farming exposure and either lung symptoms or lung function.

Structures of oligosaccharide-bound forms of the endoglucanase V from Humicola insolens at 1.9 A resolution.

Cellulose, a polymer of beta-1,4-linked glucose residues, is the major polysaccharide component of plant cell walls and the most abundant biopolymer. The underlying mechanisms of the enzymatic degradation of cellulose are of increasing commercial and ecological significance. Endoglucanase V, from the cellulolytic soil hyphomycete Humicola insolens, is an endocellulase, the catalytic core of which consists of 210 amino acids and is known to hydrolyze the beta-1,4 links with inversion of configuration at the anomeric carbon. The major products of cellulose hydrolysis are cellobiose and cellotriose. The crystal structures of the endoglucanase V (EGV) from H. insolens, in native, product (cellobiose), inactive mutant (D10N), and oligosaccharide-bound [(D10N)-cellohexaose] forms, have been determined at resolutions of 1.9 A or better. EGV consists of a six-stranded beta-barrel domain with long interconnecting loops. A 40 A groove exists along the surface of the enzyme, and this contains the catalytic residues, Asp 10 and Asp 121. The two catalytic aspartates sit to either side of the substrate binding groove in an ideal conformation for facilitating cleavage by inversion, their carboxyl groups being separated by approximately 8.5 A. The complex between substrate and inactive mutant reveals excellent density for an oligosaccharide in six of the enzyme's seven substrate binding subsites. No sugar moiety, however, is seen bound to the -1 subsite at the point of cleavage. The geometry of the cleavage site suggests that the enzyme would favor the binding of sugars with an elongated glycosidic bond, as found in the transition state, as opposed to the binding of substrate. The oligosaccharide complexes reveal solvent water suitably placed for participation in a single displacement reaction as first suggested by Koshland in 1953 [Koshland, D. E. (1953) Biol. Rev. 28, 416-436]. A large conformational change takes place upon substrate binding. This "lid flipping" has the effect of increasing the hydrophobic environment of the catalytic proton donor, enclosing the active site at the point of cleavage, and bringing a third aspartate (Asp 114) in close proximity to the substrate. Site-directed mutagenesis of the catalytic residues has been used to confirm their significance in catalysis.

[Asperger syndrome. A new diagnosis in the international classification of diseases]. / Asperger's syndrom. En ny diagnose i den internationale sygdomsklassifikation.

Asperger's syndrome (AS) is a new diagnosis in the 10th edition of International Classification of Diseases (ICD-10). AS is closely related to infantile autism and belongs to the so-called pervasive developmental disorders. The characteristics of the disorder are qualitative abnormalities in reciprocal social interaction, restricted and repetitive patterns of behaviour and interests and often motor clumsiness and problems with nonverbal and social aspects of communication. The sex ratio is about eight boys to one girl and the prevalence among schoolage boys is about 0.3%. The abnormalities normally persist into adulthood. Early diagnosis and a combination of social, educational and psychiatric interventions are necessary to relieve the stress on the person with AS and his family. Differential diagnoses and assessment are discussed.

Structure and function of endoglucanase V.

Cellulose is the major polysaccharide component of plant cell walls and is the most abundant organic compound on the planet. A number of bacterial and fungal organisms can use cellulose as a food source, possessing cellulases (cellobiohydrolases and endoglucanases) that can catalyse the hydrolysis of the beta-(1,4) glycosidic bonds. They can be classified into seven distinct families. The three-dimensional structures of members of two of these families are known. Here we report the structure of a third cellulase, endoglucanase V, whose sequence is not represented in any of the above families. The enzyme is structurally distinct from the previously determined cellulases but is similar to a recently characterized plant defence protein. The active site region resembles that of lysozyme, despite the lack of structural similarity between these two enzymes.

[Potter's sequence. Phenotype, pathogenesis, etiology and hereditary aspects]. / Potter-sekvens. Faenotype, patogenese, aetiologi og arvelige aspekter.

Potter's sequence, commonly known as Potter's syndrome, may be due to very different pathogenetic and etiological conditions. The phenotype and the pathogenesis are described. The heredity differs, depending on the etiology. The result of an ultrasound investigation of a family shows the probably most common mode of heredity: autosomally dominant with lowered penetration and variable expressivity. When genetic counselling is required, meticulous examination of the foetus and the family is recommended in order to obtain a basis for counselling of the family. Future pregnancies in the parents and relevant relatives should be followed by ultrasound examinations. With ultrasound, Potter's sequence can be demonstrated about the 16th week of pregnancy so that termination of pregnancy may be considered.

Effects of exposure to dust in swine confinement buildings--a working group report.

Pulmonary and other symptoms among workers in swine confinement buildings were evaluated by an international working group. In several studies in five different countries a total of about 2000 workers has been studied in clinical and epidemiologic investigations. Symptoms indicative of acute and chronic airway inflammation were widespread, as were systemic reactions of organic dust toxic syndrome. The base-line, and across workshift, pulmonary function changes were moderate. There was no evidence that antigen-antibody reactions are important in the pathogenesis. Longitudinal studies are recommended to establish the relationship between acute and chronic symptoms and end stage disease.

Occurrence of Aspergillus umbrosus antibodies in Danish farmers.

Antibodies to Aspergillus umbrosus were investigated in 181 Danish farmers, 137 farmers' spouses and a control group of 104 male blood donors with no relation to farming. By enzyme-linked immunosorbent assay (ELISA) higher levels of IgG antibodies were found in farmers than in their spouses and in non-farming controls (P less than 0.0001). By double immunodiffusion precipitating antibodies occurred in 11 farmers, in none of farmers' spouses and in one control subject. Farmers and farmers' spouses who were non-smokers had higher IgG antibody levels than smokers in the same groups (P less than 0.04). Farmers more than 30 years of age had higher IgG antibody levels than younger farmers (P less than 0.04). Farmers rearing cattle tended to have higher IgG antibody levels than farmers without cattle. No correlation between antibody levels and respiratory symptoms or lung function parameters (FEV1 or FVC) could be demonstrated.