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Biomedical subjects

L A Hanson

Publications and source records attributed to L A Hanson.

At least 73 records · Page 4Linked to original sources
PubMed1998

Antibody-dependent cell-mediated cytotoxicity to gliadin-coated cells with sera from children with coeliac disease.

Antibody-dependent cell-mediated cytotoxicity (ADCC) has been suggested as a contributing immunological mechanism in the disease process of coeliac disease. In the present study, sera from coeliac children were examined for their capacity to mediate ADCC against gliadin-coated target cells. The ADCC-mediating efficacy of sera were tested using monocytes from healthy adults as effector cells and gliadin-coated erythrocytes from the same donor as targets. Using monocytes as effector cells, sera from children with active coeliac disease (untreated or challenged), demonstrated significantly higher ADCC-mediating capacity than sera from healthy and disease references as well as children with treated coeliac disease. A positive correlation was found between the ADCC-mediating capacity and serum IgG as well as IgA anti-gliadin antibody levels. The results suggest that an antibody-dependent monocyte/macrophage-induced cytotoxic reaction might be involved in the disease process of coeliac disease.

Adult↗
PubMed1998

Increased antibody production against gut-colonizing Escherichia coli in the presence of the anaerobic bacterium Peptostreptococcus.

Germ-free rats were colonized with E. coli alone, or with E. coli plus Lactobacillus acidophilus and a strain of the obligate anaerobic gram-positive species, Peptostreptococcus. The presence of Peptostreptococcus reduced translocation of E. coli, but increased the serum antibody response to E. coli antigen. Whereas the immunoglobulin G (IgG) anti-E. coli antibodies largely represented cross-reactive antibodies, those of the immunoglobulin M (IgM) isotype represented true anti-E. coli antibodies because they could not be absorbed by L. acidophilus or Peptostreptococcus but could with E. coli. We suggest that peptostreptococci prime the gut immune system to other bacterial antigens and that this could be a mechanism behind the reduced translocation of facultative anaerobes in the presence of obligate anaerobes.

Absorption↗
PubMed1998

A modified fast micro method in agarose for isotype, allotype, light chain and idiotype-specific analysis of antibody clonotypes to bacterial virulence antigens.

A modified fast micro method for spectrotypic/clonotypic analysis of human IgG1-4 antibodies against bacterial virulence antigens of polysaccharide or protein nature is described. Serum samples of as small volumes as 0.5 microliter were isoelectrically focused in micro agarose gels made in plexiglass matrices and blotted using immunoaffinity-mediated capillary blotting onto nitrocellulose membranes previously coated with antigen. The bands of the antigen-specific antibodies were identified with respect to isotypes, light chain types, allotypes or idiotypes by incubating the nitrocellulose membranes with mouse monoclonal anti-human IgG subclass antisera and then with alkaline phosphatase-conjugated rabbit anti-mouse immunoglobulins. The method was applied for characterization of human monoclonals against tetanus toxoid (TT) and for the analysis of variable patterns of clonotypes in IgG subclass-deficient patients. The usefulness of the technique was also demonstrated by comparing the variable specificity and reactivity of different commercial monoclonals against human IgG subclasses. This method is fast, specific, sensitive, uses little material, is simple and reproducible.

Animals↗
PubMed1998

Placental transfer favours high avidity IgG antibodies.

The aim of the present study was to evaluate if maternal-foetal antibody placental transfer may be affected by antibody avidity. We compared the avidity index (AI) of IgG antibodies to tetanus toxoid (TT) and to type 3 pneumococcal antigen (Pn) in cord blood of 10 healthy term and 8 preterm infants and in their mothers' sera at delivery. In order to evaluate whether a heavier antigenic exposure may influence the placental transfer, we also studied 15 Pakistani maternal sera and cord blood pairs. TT- and Pn-specific antibody AI was significantly higher in Italian and Pakistani term infants than in their mothers, while a significant difference in specific TT antibody AI, but not in specific Pn antibody AI was observed between preterm infants and their mothers. Italian and Pakistani cord blood/maternal serum pairs showed comparable values of AI. Our data suggest that high avidity antibodies preferentially cross the placenta; this seems to start early during gestation and appears to be related to the nature of the antigen to which the antibodies are directed, but not to the degree of antigenic exposure.

Antibody Affinity↗
PubMed1998

Allergen sensitization of asthmatic and nonasthmatic schoolchildren in Costa Rica.

The prevalence of asthma among schoolchildren in Costa Rica is very high -- at the level of 20-30% -- and the reason is still unknown. A group of children from our previous epidemiologic study was randomly selected in order to establish the relation between asthma symptoms and allergy sensitization to common allergens. Serum samples from children with and without asthma were analyzed for the presence of IgE antibodies to 36 different allergens, for the presence of IgE antibodies to a pool of 10 common allergens, and for total serum IgE. The most prevalent IgE antibodies were those to mite, cockroach, dog, and house-dust allergens with MAST pipettes for the serologic measurements. Positive reactions to house dust, mite, cat, and the two molds (Alternaria and Cladosporium), and food allergens such as egg white, peanut, and shellfish were significantly more prevalent among the asthmatics than the nonasthmatics. Sensitization was equally prevalent at different ages, but the house-dust, mite, cat, dog, cockroach, Alternaria, and egg-white allergens had sensitized boys more often than girls (P < 0.01). The result of the analysis of IgE antibodies to a pool of 10 common allergens by Phadiatop supported the MAST pipette results, showing allergen sensitization in 57.7% of the asthmatic children and 42.3% in the nonasthmatic group. The concentration of IgE was significantly higher among the asthmatic children (372.2 kU/l) than among the nonasthmatic children (249.1 kU/l) (P < 0.00001). Parasitic infestations were not examined in this study, but in most of Costa Rica these have largely been eliminated and could not explain the high total IgE levels. Our data indicate that the very high prevalence of bronchial asthma in Costa Rican schoolchildren can be related to sensitization, especially to airborne indoor allergens such as those of mites, cockroaches, and dogs.

Allergens↗
PubMed1998

Guanine, mite, and cockroach allergens in Costa Rican homes.

Previous studies of schoolchildren in Costa Rica have shown an asthma prevalence of 23% and a high level of sensitization, particularly to mite allergens. As a continuation of these studies, some 400 dust samples were collected from various places in Costa Rica, and parts of these were analyzed for specific mite and cockroach allergens, as well as for the number of mites and amount of guanine. Guanine was quantified by a diazo, as well as an HPLC method, which were found to be highly correlated. The concentrations of guanine by the diazo method, Der p 1, Der f 1, and the number of mites were higher in bed dust than in bedroom floor dust, and it was possible to quantify mite allergens and guanine in almost all bed-dust samples. The mean levels were 2-3 times higher than the proposed risk level for elicitation of symptoms in mite-sensitive asthmatics. Bed and bedroom floor dust contained more guanine and mite allergen in humid (> 2000 mm rain) than in drier places (P < 0.05), but the number of mites in bed and bedroom floor dust was higher in less humid places (P = 0.01). The guanine content in bedroom floor dust was higher in areas with a temperate climate than in areas with a warmer climate (P < 0.001, Bartlett's chi square [BCS]), as was the number of mites (P < 0.01, Kruskal-Wallis [KW], 0.04, BCS) and the Der p 1 concentration (P = 0.01, BCS; P = 0.02, KW). The Der f 1 concentration in bedroom floor dust was higher in a warmer than in a temperate climate (P < 0.001, BCS). More guanine and mites were found in urban than in rural bed dust (P = 0.03, KW). Dust samples from the metropolitan area (temperate climate) of Costa Rica contained higher levels of guanine (P < 0.01) and Der p 1 (P = 0.07) than the coastal areas, but very little Der f 1. In these samples, guanine and Der p 1 allergen were closely related, and 2 micrograms of the allergen was equivalent to 0.49 mg of guanine. Two-thirds of bed and floor samples collected on cotton filters contained Bla g 2 allergen at mean levels of 1.6 and 2.1 units/g dust, respectively. Cockroach allergen was, however, absent in all bed samples from the metropolitan area, but did occur in very high concentrations in the coastal bed dust samples collected with tighter polyester filters. In conclusion, the concentration of guanine and Der p 1 was very high in the bed dust of Costa Rican homes. Some factors, such as humidity, small houses for large families, and type of bedding, probably favored the heavy mite infestation, which is probably related to the widespread occurrence of bronchial asthma in this country.

Allergens↗
PubMed1998

Temporal gene regulation of the channel catfish virus (Ictalurid herpesvirus 1).

To identify promoter regions that impart differential temporal regulation of channel catfish virus (CCV) genes, the transcriptional kinetics of an immediate-early gene and prospective early and late genes were characterized. A cDNA clone, designated IE3C, representing a third immediate-early transcript was identified. The 5' end of the IE3C transcript was mapped to nucleotides 15,368 and 131,043 in the terminal repeat regions of the CCV genome. The full length of the transcript represented by the IE3C clone is 1,412 bp, and it most likely codes for the protein specified by open reading frame (ORF) 12. The putative product of ORF12 contains a consensus RING finger metal binding motif (C3HC4 structure). Temporal expression studies, in conjunction with protein synthesis and DNA replication inhibition, demonstrated that the IE3C transcript belongs to an immediate-early kinetic class, the ORF5 transcript is a member of the early kinetic class, and ORF39 and ORF46 are true late-kinetic-class genes. Additionally, we demonstrated that ORF38 transcription overlaps ORF39 and the products presumably share the same poly(A) signal. The 5' ends of the transcripts encoding ORF38, ORF39, and ORF46 were mapped to nucleotides 44,862, 45,254, and 59,644, respectively, and potential transcriptional control elements were located.

Amino Acid Sequence↗
PubMed1997

Anti-gliadin antibodies in patients with celiac disease cross-react with enterocytes and human calreticulin.

One of the characteristic features of celiac disease is an increase in anti-gliadin antibodies (Abs). Recently we found that some of the monoclonal Abs to gliadin cross-react with molecules on rat enterocytes. One of these cross-reacting molecules was identified as rat calreticulin. This study shows that the levels of serum IgA Abs to gliadin, rat, and human enterocytes; purified enterocyte antigens; and calreticulin in sera from patients with active disease were significantly higher than in patients on a gluten-free diet and healthy controls (P < 0.001). Anti-gliadin Abs were isolated by affinity chromatography from the sera of six active celiac patients. The reactivity of these anti-gliadin Abs was demonstrated to be significantly higher (P < 0.05) with human enterocytes and human calreticulin than with other antigens tested. Furthermore, using isolated patients' anti-gliadin Abs bound to Sepharose 2B, two main proteins of molecular mass 62 and 66 kDa were purified from a lysate of human enterocytes. The 62-kDa enterocyte antigen was identified as human calreticulin. These findings suggest that anti-gliadin Abs may play a pathogenic role in celiac disease by cross-reacting with enterocytes. Calreticulin in enterocytes may be one of the putative targets for autoimmune reactions.

Adolescent↗
PubMed1997

beta-endorphin inhibits and facilitates lordosis behaviour in rats depending on ventricular site of administration.

beta-endorphin was administered intracerebroventricularly into the lateral and third ventricles of ovariectomized, oestrogen- and progesterone-primed rats, and its effect on lordosis and ear-wiggling was assessed. A dose of 2 micrograms beta-endorphin facilitated lordosis when infused into the lateral ventricle, but inhibited lordosis when infused into the third ventricle. The effects were the same whether measured at 30, 60 or 90 min following infusion. beta-endorphin had no significant effect on ear-wiggling frequency when administered in either ventricle. The differential effects of beta-endorphin depending on site of administration may reflect the activation of distinct opioid receptor subtypes within the brain.

Analysis of Variance↗
PubMed1997

Induction of oral tolerance with effects on numbers of IgE-carrying mast cells and on bystander suppression in young rats.

The presence of IgE+ mast cells in the small intestine, bystander suppression of DTH and antibody responses to human serum albumin (HSA) were studied in young rats, made tolerant to ovalbumin (OA) by feeding an OA-containing diet for 1-4 weeks starting from weaning, and in sensitized control rats. One week after finishing the OA diet, both groups of rats were immunized with a mixture of OA and HSA in Freund's complete adjuvant (FCA) at one site on the back. The animals were then colonized for 5 days with a genetically manipulated Escherichia coli producing OA. Immunohistochemical staining of the small intestine of the rats fed the OA diet for 4 weeks showed significantly fewer IgE+ mast cells in the lamina propria, a lower level of MHC class antigen was found in the epithelial cells and in the lamina propria, and the villus crypt depth was also significantly less in tolerant compared with sensitized rats (P = 0.003, 0.007, 0.003, respectively). Sensitized rats showed a mild diarrhoea during the colonization in contrast to tolerant rats. All rats fed OA showed a significantly reduced IgE anti-OA antibody and DTH response to OA before colonization compared with the sensitized rats. Bystander suppression of IgG and IgE anti-HSA antibody responses was also seen, but only in the rats fed OA for either 1 or 4 weeks. Rats fed the OA-containing diet for 1, 3, or 4 weeks showed bystander suppression of the DTH response to HSA. After colonization with E. coli producing OA, rats tolerant to OA after either 1 or 4 weeks on an OA diet maintained tolerance to OA and bystander suppression HSA. These results suggest that oral tolerance to OA down-regulates signs of local inflammatory response by IgE, IgG antibody and T cell responses to OA, but also provides bystander suppression to an unrelated antigen, HSA.

Administration, Oral↗
PubMed1997

Invasive Haemophilus influenzae type b (Hib) infection in an adult patient with a selective deficiency of antibody to the Hib capsular polysaccharide.

A 31-year-old woman without any underlying disease contracted severe invasive Haemophilus influenzae type b (Hib) infection but developed no antibodies to the Hib capsular polysaccharide. Serum immunoglobulin levels were normal, but she had an isolated deficiency of antibody to Hib. Subsequently, immunization with a tetanus toxoid-conjugated Hib vaccine induced only a minimal response. However, she had a protective level of antibody (> 1 microgram/mL) after the fifth vaccination.

Adult↗
PubMed1997

Variable increases of IgG and IgM antibodies in milk of IgA deficient women.

Serum, milk and saliva from seven IgA deficient mothers were studied for the presence of IgA, IgG and IgM antibodies to Escherichia coli and poliovirus antigens. Different variable patterns were obtained. One mother had very much increased IgM and IgG antibodies in milk and saliva against both antigens; the milk IgG antibodies were 11-14 times higher than the reference milk pool. Another mother showed also striking increases of both IgM and IgG antibodies in milk, as well as in saliva where the increases were much higher for the poliovirus than the E. coli antibodies. Yet another mother showed a certain increase of IgM but not of IgG antibodies in the milk. The uneven appearance of IgG and IgM antibodies in serum and secretions suggests local production. So do the differences of antibody avidities, the variations in IgG subclass distribution of antibodies and different patterns after isoelectric focusing (IEF)/immunoblotting analysis of antibody spectrotypes in secretions and serum. The study illustrates the variable patterns of compensatory increases of IgG and IgM antibodies which may occur in IgA deficiency. It also shows that the milk from IgA deficient mothers can still be rich in antibodies, in spite of the lack of secretory IgA.

Antibodies, Bacterial↗
PubMed1997

Escherichia coli K5 capsule expression enhances colonization of the large intestine in the gnotobiotic rat.

The role of capsule expression in the capacity of Escherichia coli to colonize in the large intestinal environment was studied in a gnotobiotic rat model. The rats were given perorally a mixture of two mutant strains differing in K5 expression. After 2 weeks, the rats were sacrificed, and subsequently intestinal contents, intestinal mucosae, and mesenteric lymph nodes were homogenized and bacterial numbers were quantified. Two E. coli mutant pairs were used, the first pair (972-998) lacking the O-specific side chain and the second pair (973-997) carrying the O75 lipopolysaccharide. The K5+ mutants established themselves at a higher level than the K5- mutants (10(9) versus 10(6) CFU/g [P < 0.001] for the first pair and 10(9) versus 10(8) CFU/g [P < 0.01] for the second pair, respectively). The results were confirmed by serology showing a K5+ phenotype for practically all isolates. The bacterial population associated with the mucosa was similar to that in the luminal contents with respect to the proportions of the respective mutants, and translocation occurred in numbers proportional to the intestinal population densities of the respective mutants. All mutants were able to express type 1 as well as P fimbriae. After colonization, the expression of P fimbriae remained high whereas only a minority of the isolates expressed type 1 fimbriae. The results suggest that capsule expression and P fimbriae enhance intestinal colonization by E. coli and that these virulence factors, by increasing bacterial densities in the intestine, secondarily increase translocation.

Adhesins, Escherichia coli↗
PubMed1997

Antibodies to Escherichia coli and Shigella flexneri in milk from undernourished mothers: studies on sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated antigens.

Analysis of IgA, IgM, and IgG antibodies against Escherichia coli O6, its lipopolysaccharide (LPS), and Shigella flexneri were performed in the milk of moderately undernourished Guatemalan women receiving either a low or a high calorie supplement, using SDS-PAGE. As expected, the immunostaining analysis of milk antibodies showed that IgA was the predominant isotype in both groups. Concerning the other Igs, antibodies against O6 LPS were mainly of the IgM isotype, whereas IgG antibodies were more prominent than IgM against the bacterial whole cell preparations. Seven to nine distinct bands, ranging in molecular mass from 13.5 to 109 kD were selected for each antigen to compare the milk antibodies between the two groups of women. After a 20-wk supplementation period, the IgA and IgG antibodies to the E. coli, O6 LPS, and S. flexneri were not found negatively affected by a low calorie intake. A significantly lower immunostaining intensity was, however, obtained for the low calorie intake group regarding the IgM antibody activity against four high molecular mass bands of the E. coli whole cell preparation. A decreased immunostaining intensity was also found in the same group for IgM antibodies against two bands of E. coli O6 LPS when analyzing paired samples collected at d 0 and wk 20. No differences were found for IgM antibodies against any of the S. flexneri antigens. In conclusion, the results suggest that low calorie intake does not significantly affect the production of milk IgA antibodies to E. coli and S. flexneri antigens in these women. Still, IgM antibodies against certain proteins and LPS molecules of E. coli may be decreased. IgG antibodies, although also present in milk, seemed to be directed mainly against bacterial proteins and not to LPS.

Antibodies, Bacterial↗
PubMed1997

The clonal antibody response to Pseudomonas aeruginosa heat shock protein is highly diverse in cystic fibrosis patients.

The GroEL protein of Pseudomonas aeruginosa belongs to the bacterial 60-65 kDa heat shock protein family. A strong antibody response to GroEL has been found in cystic fibrosis (CF) patients with chronic pulmonary infection caused by P. aeruginosa. Clonotypes of IgG1 and IgG2 antibodies against GroEL were studied in 60 consecutive sera from 18 CF patients with chronic P. aeruginosa infection using isoelectric focusing in combination with affinity immunoblotting. The persistent antigenic stimulation in CF patients with chronic P. aeruginosa infection induced numerous IgG1 and particularly IgG2 antibody clones against GroEL. The appearance of new clones with time reflected the long duration of the chronic infection. A striking addition of new clonotypes during the observation period occurred when a new unrelated bacterium (Burkholderia cepacia) had become established as a cause of the pulmonary infection, or when the P. aeruginosa infection became chronic.

Adolescent↗