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Biomedical subjects

S Elsayed

Publications and source records attributed to S Elsayed.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cloning and characterisation of a group II allergen from the dust mite Tyrophagus putrescentiae.

The complete cDNA encoding a major allergen from the dust mite Tyrophagus putrescentiae, Tyr p 2, has been sequenced and expressed. A degenerate primer was designed to the N-terminal amino acid sequence of the 16-kDa protein. The complete cDNA sequence was achieved by using reverse transcriptase PCR, PCR+1, standard cloning and sequencing techniques. The cDNA of Tyr p 2 is 552 nucleotides in length from the start codon including 126 nucleotides after the stop codon up to the beginning of the poly(A) tail. The leader sequence consists of 15 amino acids. Regarding the predicted amino acid sequence, there are no potential N-glycosylation sites (N-X-S/T). The sequence showed similarity to group II allergens from other mite species, and some regions are completely conserved. To show that the cloned cDNA sequence was coding for an allergen, Tyr p 2 was expressed in Escherichia coli and shown to react with a T. putrescentiae-positive serum pool.

Allergens↗
PubMed1998

Effects of beta2 adrenoceptor agonists on T-cell subpopulations.

The aim of the present communication is to determine the effects of beta2 adrenoceptor agonists on growth and cytokine secretion using allergen-specific T cells. Four beta2 adrenoceptor agonists were administered at therapeutically relevant doses (salbutamol 1-2 microM; salmeterol 0.03-0.06 microM; terbutaline 0.56-1.12 microM, and fenoterol 0.7-1.4 microM to: a) Cultures of human peripheral mononuclear cells (PBMC) b) Positively selected CD4+ and CD8+ subsets, c) Allergen-specific T-cell lines (TCL). Drug effects on growth kinetics and the secretion of IL-4, IL-5, INF-gamma and IgE following T-cell stimulation were investigated. Comparing the growth inhibitory effect of the 4 beta2 agonists at 2 different concentrations, using 12 PBMC, 10 CD4+ and CD8+ and 10 TCL cultures, the following patterns were observed: PBMC-, CD4+- and CD8+-cultures: salmeterol, followed by salbutamol and fenoterol, was a more potent inhibitor than terbutaline. In long-term TCL-cultures, salmeterol was the most potent drug, followed by fenoterol. No significant differences were observed between salbutamol and terbutaline. TCL secretion of IL-4 and IL-5 (TH2 cytokines) was also significantly inhibited. In one patient, INF-gamma secretion (TH1/THO cytokine) could be enhanced by drug administration. High IgE secretion, from 1% remaining B cells in one of the patients, following PHA+IL-2 stimulation, could be reduced by the drugs. The results showed that the beta2 agonists could influence T-cell growth and function. The changes regarding cell function were individual and related to T-cell phenotypes secreting TH1/THO or TH2 cytokines. These results suggest that administration of beta2 adrenoceptor agonists could be beneficial, not only for bronchodilation, but also for suppressing the underlying inflammatory process dominated by TH2-like cytokine secretion.

Adrenergic beta-2 Receptor Agonists↗
PubMed1997

Allergen content in dust from homes and schools in northern Norway in relation to sensitization and allergy symptoms in schoolchildren.

BACKGROUND: Previous studies have shown a high prevalence of atopic diseases among school children in the community of Sør-Varanger. Moreover, animal dander followed by pollen and house dust mite, were the most common allergens in skin prick tests. OBJECTIVE: To assess the allergen content in homes (living-rooms and mattresses) and classrooms of children living in an arctic area at 70 degrees. The presence of allergens in homes and schools and their relationship to atopy was of particular interest. METHODS: Dust samples from 38 homes and seven schools in northern Norway were collected by vacuum cleaning. The presence of allergens of dog, birch, timothy, Cladosporium herbarum, codfish and hen egg-white was investigated by radio-allergosorbent test (RAST) inhibition and the presence of major allergens of cat Felis domesticus (Fel d I) and house dust mites (HDM) Dermatophagoides pteronyssinus (Der p I) and Dermatophagoides farinae (Der f I) by enzyme-linked immunosorbent assay (ELISA). RESULTS: Mattresses contained significantly more dust per unit area than living-rooms and classrooms. No statistically significant differences in allergen content for dog, birch, timothy. Cladosporium, codfish and hen egg-white were seen between HDM-sensitized and non-atopic children. Most dust samples contained dog allergens with the highest allergenic activity found in living-rooms of those keeping dogs. An increased level of Fel d I was detected in only one of 38 samples from living-rooms (this family kept a cat) and in 25 of 38 samples from mattresses with ranges from 24 to 84 ng/m2. The highest concentrations were found in mattresses of children keeping cats. Increased levels (> or = 25 ng/m2) of Der p I were found only in homes and virtually only in mattresses of HDM-sensitized children. An increased level of Der f I was found in only one case, i.e. in the mattress of an HDM-sensitized child where additionally Der p I and HDMs were demonstrated microscopically. When relating Der p I to HDM-sensitization an odds ratio of more than 16 (95% CI: 1.6-394.3) was found. All extracts from living-rooms included codfish allergens. Low RAST inhibition values were detected for hen egg-white. Cladosporium, birch and timothy pollen in most samples. Furthermore, the study demonstrated that dust from schools was relatively free of allergens. CONCLUSION: Previous findings indicating that the main allergen exposure problem in this geographical area is that of pet allergens were confirmed.

Allergens↗
PubMed1996

Cloning of two distinct cDNAs encoding parvalbumin, the major allergen of Atlantic salmon (Salmo salar).

Allergy to fish is common in Northern Europe. Variable reactions to different fish species are usually experienced among fish allergic patients. The allergens of cod fish and particularly the major allergen parvalbumin beta (Gadus callarias) have been extensively studied in Norway. In the present communication, the white muscle parvalbumin was similarly found to be a major allergen in Atlantic salmon (Salmo salar, Sal sl). A purified salmon parvalbumin was obtained by anion exchange chromatography, gel filtration chromatography (GFC) and high-performance liquid chromatography (HPLC) of the muscle extracts. The antigenicity and allergenicity of salmon parvalbumin were confirmed using various immunologic and electrophoretic techniques. The protein is representative for several isoallergens judged by the amino acid (AA) sequence variance at certain sites in the AA sequence of CNBr cleavage peptides. Using sera from patients with cod and salmon allergy Sal sl was demonstrated to be the major allergen of Atlantic salmon, as judged by RAST- and ELISA-inhibitions and crossed radioimmunoelectrophoresis (CRIE) techniques. The protein was also demonstrated to be antigenic by the use of polyclonal cod and salmon antibodies in IgG ELISA and immunoelectrophoretic methods. Cloning of parvalbumin cDNA from Atlantic salmon was performed based on an alignment of parvalbumin AA sequences from other species. A probe was generated by PCR and used for screening a salmon muscle cDNA-library. Subcloning and sequencing of two hybridizing clones revealed transcripts from two different parvalbumin genes. The translated sequences of both clones belong to the beta-lineage of parvalbumins and include the entire coding region.

Allergens↗
PubMed1996

Serum eosinophil cationic protein and interleukin-5 in children with bronchial asthma and acute bronchiolitis.

The aim of our study was to evaluate the clinical applicability of serum eosinophil cationic protein (ECP), interleukin-5 (IL-5) and total eosinophil counts in childhood asthma and bronchiolitis. These parameters were measured in 44 children aged 12-84 months with moderate and mild asthma during symptomatic and asymptomatic phases of disease. Fifteen of the patients were included at the time of admission to hospital due to an acute asthmatic attack, and ten of these were also examined one month after discharge. None of the patients were treated with glucocorticoids or cromoglycate at any time during the study. Serum ECP was significantly increased in the children with acute asthma compared to children with stable moderate asthma, stable mild asthma, as well as to controls. There was no difference between the groups with stable asthma or between stable asthma and controls, and there was large overlap between all groups of asthmatics and controls. Detectable levels of circulating IL-5 were demonstrated in eight of 15 children with acute asthma, with significantly higher levels in atopic children, whereas all samples from children with stable asthma and controls were negative. The results suggest that even though serum ECP and IL-5 increases during acute asthmatic attacks, these parameters cannot alone be used to discriminate between different groups of young children with stable asthma, nor between asthmatics and healthy controls. In addition, the same parameters of eosinophil inflammation were examined in serum samples from 25 children aged 1-17 months undergoing their first episode of acute bronchiolitis. Children with acute respiratory syncytial virus (RSV) bronchiolitis had significantly higher levels of serum ECP than those with RSV negative disease, whereas the total eosinophil counts were significantly decreased in all patients with acute bronchiolitis. Serum IL-5 was only detected in two children with acute bronchiolitis. The results suggest that the inflammation in RSV bronchiolitis differs from that induced by other viruses.

Acute Disease↗
PubMed1996

Serum house dust mite antibodies: predictor of increased bronchial responsiveness in adults of a community.

The purpose of this study was to determine whether the presence of serum specific immunoglobulin E (IgE) antibodies was associated with increased bronchial responsiveness in adults. We studied cross-sectionally a random community sample of 18-73 year old adults, of whom 83% (n = 489) performed bronchial responsiveness testing as well as serum measurements of five specific IgE antibodies. In the crude data, 39% of those with house dust mite antibodies (n = 18) had a bronchial responsiveness < or = 32 g.L-1 methacholine compared with 19% in subjects without any of the five specific IgE antibodies (n = 453). The corresponding percentages for subjects with timothy antibodies (n = 16) was 25%, birch antibodies (n = 13) 23%, cat antibodies (n = 10) 40% and mould antibodies (n = 2) 50%. When assessing the multivariate relationship between the presence of one specific IgE antibody and degree of bronchial responsiveness we used a semi-proportional hazards model with the response as a 20% fall in forced expiratory volume in one second (FEV1) from pretest value. Covariates included in the model were: gender, age, pretest FEV1, smoking habits, pack-years, season and other specific IgE antibodies than that examined. The presence of house dust mite antibodies was a significant predictor (p < 0.01) of increased bronchial responsiveness in never- and ex-smokers. Indoor allergic sensitization (house dust mite, cat and mould) was a significant predictor of increased bronchial responsiveness, while outdoor allergic sensitization (timothy and birch) was not. Excluding subjects with obstructive lung disease (n = 39) or including the covariate log total serum IgE as a potential confounder yielded the same result. Thus, in this community, indoor allergic sensitization rather than allergic sensitization per se was related to increased bronchial responsiveness after adjusting for other relevant covariates.

Adolescent↗
PubMed1996

Specific T cell lines for ovalbumin, ovomucoid, lysozyme and two OA synthetic epitopes, generated from egg allergic patients' PBMC.

BACKGROUND: Proteins of hen egg whites are common ingredients in food and difficult to eliminate. Allergens of egg white induce allergic symptoms among relatively high numbers of patients suffering from food allergy. B cell epitopes to hen egg white major allergens have been reported. Considering that IgE antibody formation is mostly T cell dependent, the study of T cell epitopes is essential for both T cell dependent and independent IgE response. OBJECTIVES: Little information on T cell epitopes recognizing food allergens has been reported. T cell responses to hen egg white allergens and two synthetic OA peptides located at amino acid residues No. 105-122 and 323-339 were investigated. METHODS: Peripheral blood mononuclear cells from hen egg allergic patients were investigated. Various allergens of hen egg white were used for stimulation. Primary proliferation responses were detected followed by the generation of long-term cultures which were examined for their specificity, phenotype, cytokine profile and IgE production. The allergen specific T cell lines were mapped using a panel of 13 synthetic peptides of ovalbumin. RESULTS: Human T cells recognizing ovomucoid, lysozyme and ovalbumin epitope 105-122 are reported for the first time. The cell lines were enriched CD4+/CD8+ T cells (CD2+ > 95%). Ovomucoid and ovalbumin induced IgE synthesis by a small fraction of B cells (1%) present in the ovalbumin and ovomucoid specific T cell lines. CONCLUSIONS: Human T cells recognized several egg white allergens and epitopes within the ovalbumin molecule. Specific IgE was produced in cultures stimulated with ovalbumin and ovomucoid. OA peptides 105-122 and 323-339 have no affinity to the specific IgE of the two patients; an observation which could be of particular interest regarding the mechanisms of peptide-based immunotherapy.

Cell Line↗
PubMed1995

Total serum IgE and FEV1 by respiratory symptoms and obstructive lung disease in adults of a Norwegian community.

BACKGROUND: The importance of total serum IgE level on lung function impairment has not been established in a general population. OBJECTIVE: The aim of this cross-sectional community study was to examine the relationship between total serum IgE and level of lung function in adults, and whether this relationship differed by sex, age, smoking habits or by respiratory symptoms and disease status. METHODS: A stratified random sample of 18-73 year old adults from the general population were invited to spirometry and serum analyses of total and specific IgE. Of 1512 subjects invited, 82% met and performed complete examinations. RESULTS: Increasing level of total serum IgE was related to reduced lung function (P < 0.01) given as sex, age, and height standardized residuals of one second forced expiratory volume (SFEV1). Subjects with total serum IgE in the highest vs the lowest tertile had a mean SFEV1 of -0.28, corresponding to age and height adjusted FEV1 differences of 120 and 150 mL in women and men, respectively. The relationship between IgE and lung function impairment did not differ significantly by sex, age or smoking habits. In subjects with obstructive lung disease increasing level of total serum IgE was more negatively associated with lung function level than in subjects with respiratory symptoms alone. No relationship was observed in asymptomatic subjects. This was confirmed in a multiple linear regression analysis adjusting for sex, age, smoking habits and lifetime smoking consumption showing that SFEV1 was predicted by an interaction between total serum IgE level and symptom and disease status (P < 0.01). This interaction remained after excluding subjects (n = 105) having specific IgE antibodies. CONCLUSION: Increasing total serum IgE level was associated with progressively lower lung function in a general adult population after taking other predictors of impaired spirometric lung function into account, though dependent on the subjects' respiratory symptom and disease status. Variation in prevalences of respiratory symptoms and obstructive lung disease in previous examined populations may thus explain conflicting observations of the association between total IgE and airflow impairment.

Adolescent↗
PubMed1995

The effect of disodium cromoglycate (DSCG) on in vitro proliferation of CD4+, CD8+, and CD19+ cell populations derived from allergic and healthy donors.

The effect of disodium cromoglycate (DSCG) on in vitro proliferation of CD4+ and CD8+ T cells and CD19+ B cells, positively selected by immunomagnetic separation, was investigated. The cells were obtained from allergic patients with moderate serum IgE levels and mild to moderate atopic dermatitis, and healthy controls. The different cell subfractions were stimulated with mitogens or specific allergens, as well as cell supernatants from the lymphoblastoid B- (RPMI 8866) and T-hybridoma (166 A2) cell lines. Proliferative responses of T- and B-cell subsets stimulated with mitogens together with recombinant interleukin-2 (rIL-2) or accessory cells (AC) could be inhibited by DSCG. In allergic individuals, significant allergen-specific stimulation could be observed in the CD8-depleted peripheral blood mononuclear cell (PBMC) fractions. Isolated CD4+ T cells, without AC or IL-2, could also be stimulated with specific allergen, but the responses were rather low. DSCG inhibited, concentration dependently, all allergen-induced responses. Interestingly, only atopic derived CD4+ and CD8+ T cells were stimulated by soluble low-affinity IgE receptor (Fc epsilon RII/sCD23) and IgE binding factor (IgEBF), including IgE enhancing factor, present in culture supernatants from RPMI 8866 and 166 A2, respectively. These responses were also inhibited by DSCG. This was in contrast to the amplifying effect of DSCG on spontaneously proliferating RPMI 8866 and 166 A2 cells, cultured in fresh cRPMI 1640 medium without sCD23 and IgE enhancing factor. Our results show that DSCG delivers an inhibitory signal or signals to PBMC subpopulations expressing Fc epsilon RII/sCD23, either upregulated by phytohemagglutinin in normal and atopic cells, or by allergens or sCD23 in atopic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1995

The effect of H1 receptor antagonists on peripheral blood mononuclear cells, adenoid cells and primary cell lines.

This study describes the in vitro effect of three H1 receptor antagonists (dexchlorpheniramine, terfenadine and loratadine) on human peripheral blood mononuclear cells (PBMC, n = 30) from allergic patients and healthy individuals. The three H1 receptor antagonists significantly inhibited antigen/mitogen-induced PBMC proliferation in a concentration-dependent manner. Allergen-specific T-cell responses in allergic individuals were similarly inhibited. The effect of the three drugs was also tested in cultures of mononuclear cells derived from adenoid tissue. The growth kinetics were investigated using spontaneously proliferating cell lines to examine whether the inhibition was caused by general toxicity. Three cell lines, HCT 8 (an ileocaecal adenocarcinoma) RPMI 8866 (B-cell line) and 166 A2 (T hybridoma) were tested. Loratadine (< 0.03 microM) and dexchlorpheniramine (< 0.62 microM) altered the kinetics of HCT 8 and RPMI 8866, respectively. When testing RPMI 8866 and 166 A2, the growth-inhibitory effect of terfenadine and loratadine could be neutralized by addition of cell culture filtrate from RPMI 8866 or 166 A2. These culture filtrates are rich in soluble low-affinity IgE receptor (sCD23) and IgE-binding factor (IgEBF), respectively. Our findings show that the antihistamines investigated display some non-convential in vitro anti-allergic properties possibly not related to their interaction with the H1 receptor. In addition, our results suggest: a) The H1 receptor antagonists used differ in their pattern of cell inhibition; b) The inhibitory effect is completely reversible at low drug concentrations.

Adenoids↗
PubMed1995

Serum house-dust-mite antibodies and reduced FEV1 in adults of a Norwegian community.

In this cross-sectional study we investigated whether the presence of specific serum IgE antibodies to house dust mite, timothy, birch, cat, and mold was associated with a reduced FEV1 in adults. We performed complete examinations on 82% of a stratified random sample of 18 to 73-yr-old adults (n = 1,239). Subjects with house-dust-mite antibodies had lower (p = 0.002) sex, age, and height standardized residuals of FEV1 (SFEV1) than those without any specific IgE antibody. This relationship did not differ significantly by sex, age, smoking habit, total serum IgE level, or season, and remained significant after excluding subjects with obstructive lung disease. For house-dust-mite antibodies we also observed a dose-response relationship between antibody levels and impaired lung function. In a final multiple linear regression analysis the presence of house-dust-mite antibodies was the only significant predictor (regression coefficient: -0.425; SE = 0.189; p = 0.02) of reduced SFEV1 after adjusting for smoking habit and lifetime tobacco consumption, season, total serum IgE level, and respiratory-symptom and disease status. Thus, house-dust-mite allergy is an independent predictor of reduced lung function in adults of a wide age range.

Adult↗
PubMed1994

In vitro toxicity of purified gluten peptides tested by organ culture.

Various subfractions of Frazer fraction III were separated by high-pressure liquid chromatography, and their toxicity in vitro (organ culture) was tested in comparison with alpha-gliadin using duodenal biopsies from 25 patients with active celiac disease and subtotal villous atrophy, 2 patients with partial villous atrophy, and 10 nonceliac controls. One dominating fraction, designated Frazer III-2-VIII, was purified by several steps of rechromatography. It was markedly toxic to duodenal explants from patients with active celiac disease. The mean enterocyte height after culture was 15.9 microns compared with 25.6 microns in gluten-free medium. This difference was statistically significant in all cases except one, in which the lowest concentration (110 micrograms) was used. The in vitro toxicity of Frazer III-2-VIII was comparable with the toxicity of alpha-gliadin in twofold to fivefold higher concentrations. No toxicity could be detected in nonceliac explants (mean enterocyte height, 25.7 vs. 24.9 microns in gluten-free medium). The N-terminal amino acid sequence was (Gln)-Ile-Gln-Val-Phe-Pro-Ser-Gly-Gln-Val-Gln-(Trp)-Pro-Gln-Gln-(Gln)-Gl n-Pro- Phe-Pro. This sequence was not homologous to previously reported sequences of toxic gluten peptides. By use of the SwissProt and GenEMBL databases, it was concluded that the peptide Frazer III-2-VIII is part of the gamma-gliadin fraction.

Adolescent↗
PubMed1994

Total and specific serum IgE levels in adults: relationship to sex, age and environmental factors.

We studied total and specific serum IgE levels cross-sectionally, potential predictors of obstructive lung disease, in a stratified random sample of 18-73-year-old adults (n = 1512). The attendance rate was 84%. The total IgE level and prevalences of specific IgE antibodies against house dust mite and cat were higher for men than for women. Specific IgE levels decreased by increasing age, while total IgE decreased in women only. Smokers had a higher IgE level than non-smokers, while non-smokers had more often specific IgE antibodies against timothy and birch than smokers. Subjects with occupational dust or gas exposure had a higher total IgE level than unexposed. The general population prevalences were for specific IgE antibodies against timothy 4.5%, house dust mite 3.2%, birch 2.6%, cat dander 1.6% mould 0.2% and against any of these 7.6%. In a multivariate analysis age, occupational dust or gas exposure as well as the interaction terms between sex and age and between smoking and pack-years were independent predictors for total IgE levels. Male sex, young age, never having smoked and the season of the year were independent predictors for having one or more of the five specific IgE antibodies. Subjects with total serum IgE in the highest quintile (> or = 66 kU/l) had an adjusted odds ratio of 37 (95% confidence interval: 11-120) for having one or more of the specific IgE antibodies examined, compared with those in the lowest quintile (< 5 kU/l). Demographic and environmental factors were thus predictors of total and specific IgE levels in this adult community.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Dust from carpeted and smooth floors. VI. Allergens in homes compared with those in schools in Norway.

The amounts of dust, protein, and allergens in vacuumed floor covering samples taken from both schools and homes in Norway have been investigated. Classrooms contained significantly more crude dust per unit area than homes, while the mean protein content per unit area was somewhat higher in homes. The main allergen exposure problem in classrooms was that of pet allergens; the contents of dog allergens and the major cat (Felis domesticus) allergen Fel d I per unit area were significantly higher in school classrooms than in homes of families who do not keep pets. The mite and food allergens, on the contrary, were more prevalent in homes. Carpeted floors in schools and homes contained significantly more dust, proteins, and allergens than smooth floors (P < 0.05). Fel d I was detected in the vacuum cleaners' filter system in concentrations from < 1 ng to 1080 ng, confirming that this allergen can pass through the dust bag during vacuuming.

Allergens↗
PubMed1994

Epitope mapping of region 11-70 of ovalbumin (Gal d I) using five synthetic peptides.

Five successively located peptides, in region 11-70 of the major allergen of ovalbumin (OA) Gal d I (11-19, 20-33, 34-46, 47-55, 56-70), were obtained by manual solid-phase peptide synthesis. These peptides together with the previously reported OA region 1-10 comprise a segment of 70 amino acid residues located at the N-terminal of ovalbumin. The crude peptides were purified by gel filtration and reversed-phase high-performance liquid chromatographies and their sequences were verified. Polyclonal antibodies against the peptides conjugated to carrier protein (BSA) were raised in rabbits. Rocket line immunoelectrophoresis showed that four peptides (20-33, 34-46, 47-55 and 56-70), could deflect OA-line immunoprecipitates. The peptide's affinity to rabbit polyclonal Ig was examined by quantitative precipitation inhibition and the results suggested that an epitope was encompassed in segments 34-55 and 47-55. Allergenicity was tested by inhibition of specific IgE binding of ovalbumin, using several sera and a serum pool from 16 egg-allergic patients. The results showed that the allergenicity was distributed over the whole region. These findings suggested that: (a) the region 11-70 of OA seemed not to encompass continuous epitopes; (b) the antigenicity of this region was convincing for peptides 34-46 and 47-55; (c) the allergenicity, though dependent on the patient serum used, was distributed over the whole of region 11-70; (d) peptide 11-19, although weak antigenically was capable of specific IgE inhibition; (e) human and rabbit polyclonal antibodies did not show analogous affinities to the present peptides.

Allergens↗
PubMed1994

An endogenous signal triggering erythroid differentiation: identification as thyroid hormone.

The identification of thyroid hormone as an endogenous signal for erythroid differentiation began with our studies on the spontaneously differentiating murine erythroleukemia clone 3-1. We observed that the spontaneous differentiation frequency was dependent on a heat stable factor present in fetal calf serum or calf bone marrow. We also noted that the bone marrow extract stimulated erythroid colony-forming units in mouse bone marrow cells, suggesting the relevance of this factor in normal erythroid differentiation. The bone marrow extract did not supplant the requirement of erythropoietin but was synergistic. Purification of the bone marrow extract indicated that the differentiation-inducing activity for clone 3-1 cells cochromatographed with a low-molecular-weight, UV (280 nm)-absorbing component(s). These observations and previous reports identifying the avian erythroblastosis virus oncogene v-erbA as a mutated thyroid hormone receptor which blocked erythroid differentiation led us to test thyroid hormone in our assay. Both triiodothyronine and thyroxine were highly active, and the active constituents in the chromatographically purified fraction were identified as triiodothyronine and thyroxine. Although thyroid hormone action has been associated with both in vivo and in vitro erythroid differentiation, its role has been often relegated to a secondary status. We suggest that thyroid hormone is required for the commitment of erythroid cells to terminal differentiation.

Animals↗
PubMed1993

[Indoor climate and allergy. The prevalence of allergens in Norwegian primary schools].

We have investigated the prevalence of allergens from cat, dog, house dust mite, pollen, mould and food in dust samples from schools and homes in Norway. Occurrence of cat and dog allergens in schools was surprisingly high, especially in classrooms with carpeted floors. Cat and dog-derived allergens are brought into schools through the pupils' outside contact with pets. Children who are in contact with pets at home or in their surroundings carry animal hair and dander into the classrooms on their clothes, shoes and bags. The schools seemed to be a protective environment against mite infestation, as verified by very low content of mites in both carpeted and smooth floors. Furthermore, while cat and dog allergens were more prevalent in schools than in homes without pets, mite and food allergens were more dominant in homes. Frequent cleaning is important in schools, to prevent accumulation of animal hair and dander in the classrooms. We emphasize the obvious advantages of linoleum floors over carpets in decreasing the pupils' level of exposure to indoor allergens and dust.

Air Pollution, Indoor↗