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I Søndergaard

Publications and source records attributed to I Søndergaard.

At least 19 recordsLinked to original sources
PubMed1996

From image processing to classification: IV. Classification of electrophoretic patterns by neural networks and statistical methods enable quality assessment of wheat varieties for breadmaking.

The end-use quality of products made from doughs consisting of wheat flour and water is often dependent upon the storage (gluten) proteins of the grain endosperm. Today the electrophoretic patterns of the high molecular weight (HMW) glutenin subunits are used for quality selections in wheat breeding programs in several countries. In this study, we used two multivariate techniques to classify digitized patterns from isoelectric focusing of gliadins and glutenins: a two-layered neural network architecture consisting of a self-organizing feature map and a feed-forward classifier [1], and discriminant analysis [2,3]. Three groups of seven wheat varieties (Triticum aestivum L.), associated with poor, medium or good properties in relation to bread-making quality, were used. The best classification results were obtained by the neural network model, based on data from the gliadin fraction: it was possible to classify varieties associated with poor or good quality, with recognition rates of 70 and 69%, respectively. The statistical method was better suited to solve the classification problem when the data was based on the glutenin fraction: if a specific variety was already known to be non-poor, this method enabled us to classify the medium- and good-quality classes with recognition rates of 90 and 88%, respectively. The results obtained were confirmed by correlation coefficients.

Discriminant Analysis↗
PubMed1996

Determinants of decision-making in the screening procedure of a community psychiatric service.

This study is a predictor analysis of the screening procedure followed by a psychiatric service for a period of 1 year preceding and a period of 1 year following the introduction of community psychiatry. Throughout this period, the psychiatric service consisted of a local service within the catchment area and a central service at a psychiatric hospital outside the area. At the time of the reorganization, the responsibility for the psychiatric service was transferred from the public health authorities to the social services. Before the reorganization, screenings were conducted on the basis of referral papers or simply as a result of telephone communication. After the reorganization, the screening procedure was intensified by means of a pre-examination. One aim of the reorganization was to ensure that the severely mentally ill take priority over patients characterized predominantly by social strain. Patients with manic-depressive psychosis and other psychoses showed a significantly increased probability of being accepted for treatment, whereas those with schizophrenia showed no significant increase, irrespective of the service reorganization. Similarly, manic-depressive psychosis and other psychoses (not schizophrenia) were significant predictors of hospitalization at the mental hospital outside the catchment area as well as hospitalization in the local facilities, irrespective of the service reorganization. Indicators of social strain were not given higher priority following the service reorganization.

Adult↗
PubMed1995

From image processing to classification: I. Modeling disturbances of isoelectric focusing patterns.

In order to optimize the conditions for evaluation of isoelectric focusing (IEF) patterns by digital image processing, the sources of error in determination of the pI values were analyzed together with the influence of a varying background. The effects of band distortions, in the spectra of the individual lanes, were examined. In order to minimize the effect of these distortions, optimal conditions for handling IEF patterns by digital image processing were elucidated. The systematic part of the global deformation on the gels was investigated and an algorithm was developed by which it was possible to correct for a part of the individual distortions. The effects of various corrections for lane distortions were illustrated by classification, using different types of discriminant analysis. Finally the background disturbances were examined, and described by a mathematical model.

Algorithms↗
PubMed1995

From image processing to classification: II. Classification of electrophoretic patterns using self-organizing feature maps and feed-forward neural networks.

In a recent study, isoelectric focusing patterns were classified with a neural network using the back-propagation algorithm [1]. In order to further study the classification process and to generalize the presentation of electrophoretic patterns, Kohonen's self-organizing feature maps [2] were applied in this study. Although these feature maps are very efficient in many pattern recognition tasks, our data proved to be too complex for classification with an unsupervised system. Therefore, a second supervised network on top of the feature map was necessary. As in [3], a feed-forward network trained by the back-propagation algorithm was used. The final system allows us to correctly classify 90% of all wheat varieties. Moreover, the system proved to be reliable, reasonable in training time and shows the same accuracy in different experimental setups.

Algorithms↗
PubMed1995

From image processing to classification: III. Matching patterns by shifting and stretching.

A method for the classification of electrophoretic patterns is described and tested on a data set representing ten wheat varieties. The method attempts to match each electropherogram to each variety by a transformation involving displacement and stretching along the x-axis. This is done essentially by the method of least squares, which uses only the information contained in the electropherogram itself to adjust it to the variety in question. The method is completely automatic and works extremely well by classifying 98% of the spectra correctly, judged by cross validation.

Algorithms↗
PubMed1994

Classification of wheat varieties by isoelectric focusing patterns of gliadins and neural network.

Classification of wheat varieties, using isoelectric focusing patterns of the gliadins, image processing and neural networks, is described. The method was compared to a statistical classification method, discriminant analysis. The isoelectric point and the area of each band were calculated by image processing. Different methods of presenting the electrophoretic patterns to the neural network were studied. The most effective method was transformation of the electrophoretic pattern to a small (11 x 47 pixels) representation of the original digitized image, which was presented to the neural network as a vector. The neural network was trained with a number of patterns and tested with new patterns from different electrophoretic runs of the same wheat varieties. In this study we used ten different wheat varieties and the neural network was able to classify 95.5% of the patterns correctly. The statistical classification method classified the same data set 91.8% correctly. We conclude that both the neural network and discriminant analysis were able to classify the patterns correctly with a high degree of certainty. The patterns that were misclassified were indistinguishable by visual inspection.

Discriminant Analysis↗
PubMed1992

Classification of crossed immunoelectrophoretic patterns using digital image processing and artificial neural networks.

A method is presented which makes it possible to present crossed immunoelectrophoretic patterns to an artificial neural network. The electrophoretic patterns are presented for the artificial neural network as three-dimensional vectors and it is shown that it is possible with this representation to train the network to learn the patterns and classify them. It was found that the ability to generalize was substantially increased by the addition of noise to the input patterns during training. Furthermore, the addition of noise decreased the number of presentations needed to reach the predetermined error level. The trained neural network was able to classify all distorted patterns correctly within an error range of 1%.

Image Processing, Computer-Assisted↗
PubMed1992

Evidence of a common regulation of IgE and IgG-subclass antibodies in humans during immunotherapy.

Based on a 3-year prospective study of 20 pollen-allergic patients, where a detailed analysis of the IgE, IgG1 and IgG4 immune response was performed, we propose that a common regulatory mechanism exists between the IgE and IgG1 synthesis and between IgE and IgG4 synthesis during immunotherapy. It was found that the IgE immune response to a number of antigens was quantitatively diminished during the period of immunotherapy when IgG1 was present early (week 12), and for other antigens there was a rise in IgE without an early IgG1 antibody response. Additionally, it was found that for some antigens a rise in IgE antibodies was contrasted by a fall in the IgG4 antibody response and for other antigens the opposite was true, indicating a regulatory mechanism between the IgE and the IgG4 synthesis. A statistical analysis showed that these findings were statistically significant at the 0.01% level for the IgE/IgG1 relationship and at the 0.05% level for the IgE/IgG4 relationship. These findings could have implications for future immunotherapy regimens.

Desensitization, Immunologic↗
PubMed1991

A computational approach to the description of individual immune responses. IgE and IgG-subclass allergen-specific antibodies formed during immunotherapy.

Detailed evaluation of the IgE and IgG-subclass immune response during immunotherapy can now be performed by crossed radio immunoelectrophoresis (CRIE). Some new concepts are introduced facilitating the handling of the vast amount of data obtained by quantitating the immune response. These concepts are "distance" between antibody responses and "immune response width". The 20 patients included in this study were pollen-allergic patients who underwent specific immunotherapy in a 3-year prospective study. It was found that the immune response during immunotherapy was restricted to IgG1 and IgG4 antibodies. The semi-quantitative CRIE analysis correlated with the RAST analysis for the IgE samples before start of immunotherapy, for the IgG1 samples at week 12, and for all the IgG4 samples. During immunotherapy the number of IgG1 antibodies directed to the different antigens increased towards 11 antigens and decreased towards six. For the IgG4 antibodies the number of reactions increased towards 15 antigens and decreased towards four. The increase is generally paralleled by an increase in quantitative immune response as well. For some of the antigens a rise in the IgE antibodies is contrasted by a fall in the IgG4 antibody response, and for other antigens the opposite was true, indicating a regulatory mechanism between the IgE and the IgG4 synthesis. The IgE immune response to a number of antigens, including the major allergens before the start of immunotherapy, was quantitatively diminished during the period of immunotherapy when IgG1 was present early (week 12) in the period, and for other antigens there was a rise in IgE without an early IgG1 antibody response. This suggests that IgG1 can have a regulating influence on the IgE synthesis. Finally, we have found that IgE antibodies with specificities not present in the samples taken before immunotherapy were formed during immunotherapy. These new IgE antibodies do not, however, seem to impair the outcome of treatment.

Antigens↗
PubMed1991

Allergen-containing immune complexes used for immunotherapy of allergic asthma. II. IgE and IgG immune response during and after hyposensitization of sensitized guinea pigs.

In a previous study guinea pigs inbred for their ability to develop respiratory anaphylaxis to experimental antigens have been used for comparison of different forms of immunotherapy (IT). Passive, active and combined (immune complexes prepared from antigen and specific IgG) IT was compared with placebo. In the present study methods were evaluated for determination of the allergen-specific IgE and IgG. IgE was determined by the passive cutaneous anaphylactic test (PCA) and the variability of this test on different strains of the recipient guinea pig was investigated. The same strain as used for the IT study was found to produce the most potent response. Radioimmunometric assays (RIA) were developed and validated for determination of specific IgG1 and IgG2. The IgE and IgG immune response in animals from the IT study were then evaluated by means of PCA and RIA. Animals from all four treatment groups were sensitized during the first part of the IT study, and responded with a marked IgE synthesis which later stabilized on a more moderate level. In spite of notably reduced symptoms in groups treated with active and combined IT, no difference in the IgE level was found between the four groups. In contrast to IgE, mean group titers of IgG1 and IgG2 in the groups receiving active or combined IT rose drastically during the first part of therapy and closely paralleled the clinical response during the rest of the study period. However, in the individual animals, no correlations were found between immune response and clinical symptoms. Thus, the strong IgG response during immunotherapy may not be causally related to the outcome of treatment.

Animals↗
PubMed1990

Immunochemical cross-reactivity between albumin and solid-phase adsorbed histamine.

For production of an antibody against histamine, this was coupled to human serum albumin (HSA) and used for immunization of rabbits. To test the antiserum, an immunoradiometric assay was developed comprising solid-phase bound histamine, antisera and radiolabelled protein A. Titration and inhibition experiments revealed that histamine adsorbed onto a solid-phase could bind the antiserum. However, neither free histamine nor histamine coupled to unrelated carriers could inhibit the binding of antiserum to the solid-phase histamine. Cross-reactivity was demonstrated between HSA and solid-phase bound histamine, as the immunoradiometric assay was inhibited by HSA. This unexpected cross-reactivity was established, as a commercially available antiserum with specificity to HSA without histamine also bound to the solid-phase bound histamine. It is suggested that preparations of antibodies against histamine are tested for this possible cross-reactivity.

Adsorption↗
PubMed1989

Allergen-containing immune complexes used for immunotherapy of allergic asthma. Preparation of complexes and evaluation of their clinical performance in guinea pigs.

Guinea pigs inbred for their ability to develop respiratory anaphylaxis to experimental antigens have been used for comparison of different forms of immunotherapy (IT). Passive, active and combined (immune complexes between antigen and specific IgG) IT were compared with placebo. The bronchial reactivity of the animals to the antigen was monitored regularly before, during (35 weeks) and after IT (20 weeks). Animals treated with passive IT did not improve clinically. Active and combined IT abolished most symptoms within 7 weeks of treatment. During the post-treatment period, animals from both groups surprisingly recovered their original sensitivity to inhalation of the antigen.

Allergens↗
PubMed1989

Maxisorp RAST. A sensitive method for detection of antigen-specific human IgE in culture fluids.

For determination of allergen-specific IgE in cell culture supernatants and other highly diluted IgE preparations a radioallergosorbent test (RAST) based on high adsorption polystyrene test tubes has been developed ("Maxisorp RAST"). Cladosporium herbarum extract was used as a model allergen but timothy grass pollen, house dust mite and dog dander showed similar results. The test showed specificities of both allergen and immunoglobulin isotype and significant correlations (r = 0.67-0.88) with established RAST procedures were found. Based on immunosorbent-purified allergen-specific IgE the estimated sensitivity was within the order of 150-300 pg allergen-specific IgE per ml. The within-assay variation was 4-9% and the inter-assay-variation 17-29%. The Maxisorp RAST is useful as an inhibition assay for quantitating allergenic activity down to 0.1 biological units/ml of allergen extracts.

Allergens↗
PubMed1988

Preparation of patient-related allergens for hyposensitization. Qualitative aspects.

An affinity chromatography method for preparation of patient-related antigens from commercially available allergen extracts has been investigated. IgG1,2,4 from a patient previously hyposensitized with dog hair and dandruff allergen was bound to protein A-sepharose. Secondly, commercial allergen extract was applied to the immunosorbent, and patient-related antigens were selectively absorbed by the specific antibodies from the patient serum. Finally, immune complexes containing antigen and IgG were eluted. Alternatively, the antigens alone were purified by retaining the IgG on the column by means of a covalent reinforcement of the protein A-IgG-binding. Purified, patient-related antigens were investigated in crossed immunoelectrophoresis and identity to IgG- and IgE-binding antigens (as determined by the CRIE-technique) was suggested. The affinity purified IgG was unaltered with regard to protein A-binding, binding of antigen and affinity for monoclonal antibody to human IgG-subclasses. Further, it was demonstrated that the antigen-binding capacity of IgG in the immune complexes was intact as evidenced by strong affinity to antigens even at low pH. The antigens eluted together with IgG were predominantly found in immune complexes with a molecular weight of greater than 300 kdalton equivalent to 2 or more molecules of IgG. The possibility of employing a similar method with IgE instead of IgG for preparation of patient-related allergens instead of antigens, is discussed.

Allergens↗
PubMed1988

Increased urinary excretion of 1.4-methyl-imidazoleacetic acid in patients with atopic dermatitis.

To investigate whether the overall histamine turnover is increased in patients with atopic dermatitis, without respiratory disease, the urinary excretion of the main histamine metabolite 1.4-methyl-imidazoleacetic acid (MIAA) was examined in 23 patients and in 23 age- and sex-matched non-atopic controls. The patients excreted significantly more MIAA than the controls. One third of the patients however, showed MIAA excretion within or below normal range. The MIAA excretion was neither correlated to the severity of the eczema nor to the total serum IgE. It was concluded that histamine does not play a significant role in the pathophysiology of atopic dermatitis, and that the great variation in MIAA excretion, and hence the histamine turnover, reflected the spectrum of histamine releasability in the patients.

Adolescent↗
PubMed1988

IgG subclass concentrations in sera from 200 normal adults and IgG subclass determination of 106 myeloma proteins: an interlaboratory study.

The IgG subclass protein concentrations in sera from 200 normal subjects were determined independently in two laboratories, using the same technique (radial immunodiffusion), the same subclass-specific antibodies and the same calibrator. The coefficients of correlation (rs) between IgG subclass concentrations determined in the two laboratories were 0.487, 0.883, 0.928 and 0.926 for IgG1, IgG2, IgG3 and IgG4, respectively (p less than 0.0005 in all four cases). By the chi-square test for goodness of fit, the frequency distributions observed in the two laboratories were found to differ significantly for all four subclasses (p less than 0.01). In one laboratory, the distributions of IgG1 and IgG2 were not significantly different from normal distributions, whereas the distributions of IgG3 and IgG4 deviated significantly. In the other laboratory, all four subclass distributions were significantly different from normal distributions. In the first laboratory, the IgG2 concentrations were log-normal distributed, whereas in the second, IgG1, IgG2 and IgG4 concentrations were log-normal distributed. We conclude that use of identical reagents does not ensure identical frequency distributions. This finding emphasizes the need for standardization of the measurement technique too. Furthermore, we argue that at present, intralaboratory reference intervals for IgG subclass protein concentrations are necessary. The reference intervals should be based on non-parametric statistics. The subclass of 106 monoclonal IgG proteins, which were demonstrated by agarose gel electrophoresis, was identified by RID for 89 samples. The subclass of the remaining 16 M-components was readily determined by qualitative immunoelectrophoretic analysis using the same subclass-specific antibodies.

Adult↗
PubMed1987

Image processing and pattern recognition algorithms for evaluation of crossed immunoelectrophoretic patterns (crossed radioimmunoelectrophoresis analysis manager; CREAM).

A computerized method for automatic evaluation and comparison of crossed immunoelectrophoretic and crossed radioimmunoelectrophoretic patterns that requires limited hardware resources has been developed. For the initial reading of the plates an ordinary video camera is used. Feature extractors that allow the computer to recognize a point on the precipitation curve as being a peak point have been developed. After this automatic procedure the program allows for an interactive menu-driven proofreading phase during which it is possible to force the system to take into consideration any number of extra points along the precipitation curve in the curve-fitting process. The system has been tested on crossed immunoelectrophoretic patterns as well as crossed radioimmunoelectrophoretic patterns and it has been shown that the system can recognize the same precipitation curves on different immunoplates and autoradiographs. In addition, the system reports the mean, the variance, and the area of the precipitation curves, thus allowing not only a qualitative comparison of two or more plates but also a quantitation of individual antigens or antibodies.

Algorithms↗