Ovalbumin Concentration Research Articles

Guanosine and inosine (riboxin) eliminate the long-lived protein radicals induced X-ray radiation

A considerable part of damages of biopolymers incells, occurring under exposure to ionizing radiation,are due to short-lived radicals produced as a result ofwater radiolysis [1]. EPR spectroscopic studies showedthat exposure to ionizing radiation leads to generationof long-lived protein radicals in protein solutions andcells [2–11]. The half-life of these radicals reaches 20[2] and more hours [11]. The occurrence of long-livedradicals was demonstrated in model systems for someproteins, such as egg albumin [3, 5, 6], bovine serumalbumin [7, 12], human serum albumin [9], lysozyme[12], immunoglobulin G [9], and histone H1 [10].Long-lived radicals are formed under exposure togamma- [3–6, 10, 11], X-ray [2], and ultraviolet radia-tion [8], as well as in the presence of peroxynitrite [9]and the products of hydrogen peroxide decompositionby immobilized peroxidase [7]. The formation of suchradicals was detected in human blood plasma proteins[9]; human [2] and hamster [5] embryonic cells; Droso-phila germ cells; and in root, seed, and leaf cells of gar-den radish and Arabidopsis [4].It was established that the long-lived protein radi-cals may be the sources of generation of reactive oxy-gen species and long-term oxidative stress in biologicalsystems [7] and function as messengers transmittingoxidative damages to other molecules, including DNA[10]. An exposure of histone H1 to gamma-radiationyields radicals that are involved in the formation ofDNA–protein crosslinks and oxidative damage of basesin DNA, producing the mutagenic product 8-oxogua-nine [10]. It was shown that the long-lived protein rad-icals induce mutations and lead to cell transformation[2, 3]. However, normally these radicals are producedin small quantities in living animal and plant cells [4].The long-lived protein radicals can be immediatelyrecorded using ESR spectroscopy; however, a low sen-sitivity of this method makes it possible to detect theformation of such radicals only at very high radiationdoses (1–5 kGy) [3, 5, 6, 10, 11]. Another effective andsensitive method to detect free-radical reactions ischemiluminescence, when interaction of radicals yieldsenergy emitted in the form of light quanta [1]. In thiswork, we detected and studied long-lived protein radi-cals by measuring the intrinsic chemiluminescence ofprotein solutions induced by X-ray radiation using ahigh-sensitivity Biotoks-7A chemiluminometer (Rus-sia). Measurements were performed in 20-ml plasticpolypropylene vials for a liquid scintillation counter(Beckman, United States). The use of larger volumesfor measuring chemiluminescence compared to theconventionally used volumes (at most 0.1 ml) allowedus to significantly (more than 200 times) increase thesensitivity of this method and to detect the formation ofprotein radicals at doses of several Gy. To study chemi-luminescence, we used solutions of ovalbumin (Rea-Khim, Russia) prepared in 20 mM Tris-HCl buffer(pH 8.0). The samples were irradiated using a RUT-15therapeutic X-ray device (Russia) under the followingconditions: voltage, 200 kV; amperage, 20 mA; focusdistance, 37.5 cm. Samples containing unirradiatedprotein and protein-free irradiated samples were usedas controls. The dependence of chemiluminescenceintensity on ovalbumin concentration was bell-shaped;the maximum chemiluminescence intensity (irradiationdose, 7 Gy) was detected for 0.5% ovalbumin. This pro-tein concentration was used in further experiments.To rule out the effect of light quanta as a result ofrecombination of radical occurring upon decomposi-tion of hydrogen peroxide and other possible productsformed in the buffer, the chemiluminescence intensitywas measured 1 h after irradiation. During this time,samples were kept at room temperature in the dark.Because water radiolysis yields hydrogen peroxide,which has a long half-life, we studied the possibility ofinfluence of hydrogen peroxide on the chemilumines-cence yield in irradiated protein solution. We found that

Effect of a prebiotic‐enriched phytocompound in improving ovalbumin allergenicity

The aim of the present study was to test a prebiotic-phytotherapic compound in an experimental model of oral allergenicity. Antigen-specific immunoglobulin E (IgE) elevated mice were prepared by injecting them intraperitoneally with 10 microg of ovalbumin. Subsequently, the mice were exposed to ovalbumin solution intranasally and blood samples were obtained on weekly intervals for 4 weeks to measure serum-ovalbumin-specific IgE and total immunoglobulin G. Mice with high titers of ovalbumin-IgE were intragastrically administered with 0.3 mL of phosphate buffered solution containing either 20 mg of ovalbumin, the same solution with 5 mL of milk, or 20 mg milk added to prebiotic-phytocompound. Ovalbumin administration caused a significant increase of plasma ovalbumin concentration in sensitized mice while prebiotic-phytocompound-supplemented mice showed a significantly reduced peak value (P < 0.05). Prebiotic-phytocompound added to milk exerted a significant effect in lowering the ovalbumin-IgE level and the total immunoglobulin G level as compared to control plain milk (P < 0.01). This study provides a rationale basis for a feasible non-pharmacological therapeutic strategy in food allergen hypersensitivity syndromes.

Early Events in the Binding of the pPS10 Replication Protein RepA to Single Iteron and Operator DNA Sequences

RepA protein, encoded in the Pseudomonas pPS10 replicon, is a stable dimer in solution (dRepA), acting as a self-repressor of repA transcription through binding to an inverted repeat operator. However, RepA monomers (mRepA) are required to initiate plasmid replication upon binding to four directly repeated DNA sequences (iterons). RepA is composed of two winged-helix (WH) domains: C-terminal WH2 is the main DNA-binding domain (DBD) for both target sequences, whereas N-terminal WH1 acts as dimerization interface in dRepA, but becomes a second DBD in mRepA. On the basis of CD spectroscopy, hydrodynamics, X-ray crystallography and model building studies, we proposed previously that the activation of RepA initiator implies a large structural change in WH1, coupled to protein monomerization and interdomain compaction. Here, we report novel features in the process. Binding curves of RepA to an iteron, followed by fluorescence anisotropy in solution and by surface plasmon resonance on immobilized DNA, exhibit the profiles characteristic of transitions between three states. In contrast, RepA-R93C, a monomeric activated mutant, exhibits a single binding transition. This suggests the presence of an intermediate species in the iteron-induced dissociation and structural transformation of RepA. High concentrations of bovine serum albumin or ovalbumin (macromolecular crowding) enhance RepA affinity for an iteron in solution and, in gel mobility-shift assays, result in the visualization of novel protein–DNA complexes. RepA-induced DNA bending requires the binding of two WH domains: either both WH2 in dimers (operator) or WH1 plus WH2 in monomers (iteron).

Batch foam separation of a soluble protein

Removal of protein dissolved in water by batch foam separation was conducted with using ovalbumin (OA) as a model protein in the light of wastewater treatment reducing organic loading. The removal efficiency had a maximum value near the i.e.p. of OA (pH 4.6); thus, most experiments were conducted at pH 4.6. Typical experimental conditions; superficial gas velocity, U(g): 1.97 x 10(-2)-5.37 x 10(-2)cm/s; initial bulk concentration of OA, C(i): ca. 0.05-0.25 g/L; liquid volume, V: 600 cm(3). A model estimating bulk concentration profile was proposed by taking into account a mass balance of the present system. The model predicted that OA could be removed perfectly, however, was not all removed experimentally. The residual OA concentration of the bulk liquid within the column reached plateau value, which correspond to ca. 18% of the initial OA concentration. The plateau value of the bulk concentration was attained for ca. 100-500 min with U(g)=1.97 x 10(-2)-5.37 x 10(-2)cm/s. Foaming ability test revealed that the foaming limit concentration of OA at pH 4.6 was 9.72 x 10(-3)g/L. These results suggested that OA molecules could be damaged by interaction of bubble surface in the dispersed phase, since there were the residual OA concentrations over the limit concentration. To take account of this phenomena and correct the model, average surface density, X(d), which should convert protein molecule into the denatured protein molecule, was introduced. The corrected model could explain well the time profile of OA bulk concentration.

Alterations in the colonic flora and intestinal permeability and evidence of immune activation in chronic constipation

Background. Disturbances in bowel function in chronic constipation could result in changes in the colonic flora and lead to disordered immunity and to decreased resistance to pathogenic flora. Aim. To investigate systemic immunity, the faecal flora and intestinal permeability in patients with chronic constipation, under basal conditions and following therapy with the laxative Bisacodyl. Methods. Intestinal permeability, faecal flora analysis, T- and B-lymphocyte numbers, T-cell subpopulations, lymphocyte proliferation, phagocytosis, intracellular killing of Staphylococcus aureus by neutrophils, as well as circulating levels of immunoglobulins, immune complexes and antibacterial antibodies were assessed in 57 patients with functional constipation. In 12 patients with severely delayed transit, investigations were repeated following therapy with Bisacodyl. Results. Ovalbumin concentrations, in serum, were higher in constipated patients (28.2 ± 4.1 ng/ml versus 1.0 ± 0.4 ng/ml, p < 0.05). Elevated counts of CD3+, CD4+, CD25+ cells, increased spontaneous proliferation of lymphocytes, elevated titres of antibodies to Escherichia coli and S. aureus, diminished counts of CD72+ B cells, diminished lymphocyte proliferation under phytohemagglutinin (PHA) stimulation and a diminished phagocytic index for both neutrophils and monocytes were found in the constipated patients. Concentrations of Bifidobacterium and Lactobacillus were significantly lower in constipated patients; potentially pathogenic bacteria and/or fungi were increased. Therapy with Bisacodyl resulted in normalisation of the faecal flora, a reduction in ovalbumin concentration and return towards normal for certain immunologic parameters. Conclusion. Constipation is associated with striking changes in the faecal flora, intestinal permeability and the systemic immune response. Relief of constipation tends to normalise these findings suggesting that these changes are secondary to, rather than a cause of, constipation.

EFFECTS OF AZELASTINE AND SODIUM CROMOGLYCATE IN THE INHIBITION OF BRONCHO - CONSTRICTION OF OVALBUMIN SENSITIZED LUNG PARENCHYMAL TISSUES OF GUINEA PIGS IN VITRO

OBJECTIVE: To see the ability of Azelastine and Sodium cromoglycate in influencing antigen induced contractile responses in isolated parenchymal tissues of Guinea pig in vitro. DESIGN: An experimental study. SETTING: Department of Pharmacology and Therapeutics of Basic Medical Sciences Institute, Jinnah Postgraduate Medical Center (JPMC), Karachi during 1998. METHODS: The Guinea pigs (n=10) were sensitized with ovalbumin and their parenchymal strips were exposed to different concentrations of ovalbumin to observe the EC50. Each sensitized parenchymal strip was treated with either Azelastine or Sodium cromoglycte in an organ bath for 10 minutes and treated with EC50 ovalbumin and contraction was recorded by Grass Polygraph model 7B. RESULTS: EC50 (n=6) of parenchymal strips (0.3x10 -6 + 0.16x10 -6 g/ml) produced a mean response

Effect of cooked and raw egg consumption on ovalbumin content of human milk: a randomized, double‐blind, cross‐over trial

Maternal avoidance of egg intake has been recommended to treat egg allergy in breastfed infants. To determine if the concentration of ovalbumin (OVA) in human milk is directly related to the quantity and form of egg consumed by breastfeeding mothers. Randomized, blinded, cross-over, intervention trial. Breastfeeding women (n = 41) attended four clinic days between 11 and 14 weeks of lactation and on each day were randomly allocated to receive a test breakfast, identical except for the egg content (no egg, one raw egg, half a cooked egg or one cooked egg). Breast milk samples were collected at two hourly intervals for 8 h and their OVA concentration measured by ELISA. There was a direct, dose-response between the amount of cooked egg ingested and the peak OVA concentration (no egg 0.05 ng/mL [95% confidence interval (CI), 0.01-0.11], half a cooked egg 2.24 ng/mL [95% CI, 0.57-3.91], one cooked egg 3.16 ng/mL [95% CI, 1.41-4.91], n = 41, P<0.05) as well as the total OVA excretion (no egg 0.18 ng/mL/h [95% CI, 0.04-0.39], half a cooked egg 4.93 ng/mL/h [95% CI, 1.40-8.46], one cooked egg 9.14 ng/mL/h [95% CI, 4.25-14.03], n = 41, P<0.05). The peak concentration and total OVA excretion in response to one raw egg did not differ from ingesting half a cooked egg. There was no detectable OVA in the breast milk of 24% (10/41) women up to 8 h after any egg challenge. OVA was detected in the breast milk of lactating women up to 8 h after a controlled intake of egg. A dose-response correlation was indicated. As excretion of OVA in human milk appears to be a normal phenomenon, further studies need to determine the threshold of OVA excretion that leads to symptoms in egg-allergic breastfed infants.

Influenza vaccine in 55 patients with egg allergy

RATIONALE: Egg allergy prevents many patients from receiving influenza vaccine. Clinical predictors of vaccine reaction might help in determining safety of administration.METHODS: 55 patients diagnosed with egg allergy confirmed by positive SPT and/or egg specific IgE underwent skin testing for flu vaccine. Patients with negative SPT received vaccine; those with positive SPT had vaccine administration deferred in most cases. Clinical and laboratory profiles were obtained to include asthma history, presence of other food allergy, and level of egg specific IgE. ELISA was conducted on selected vaccine lots to determine ovalbumin concentration.RESULTS: Clinical history of egg allergy ranged from eczema to wheezing. 45/55 patients had asthma and 52/55 had other food allergy. 32/55(58%) had negative SPT and 23/55(42%) had positive SPT. All 32 patients who were SPT negative to vaccine were immunized with 4 patients developing mild localized cutaneous reactions and 1 patient developing mild wheezing. Of the 23 patients who were SPT positive to vaccine 5 were immunized and none developed reactions. Detected ovalbumin concentration in three vaccine lots ranged from 4.9 ug/mL to 14.6 ug/mL.CONCLUSIONS: In our study patients with egg allergy were safely immunized with influenza vaccine. Current recommendations for influenza vaccine and egg allergy remain the safest and most reliable approach to administration (Zeiger RS. Current issues with influenza vaccination in egg allergy. JACI 2002;110:830-40). RATIONALE: Egg allergy prevents many patients from receiving influenza vaccine. Clinical predictors of vaccine reaction might help in determining safety of administration. METHODS: 55 patients diagnosed with egg allergy confirmed by positive SPT and/or egg specific IgE underwent skin testing for flu vaccine. Patients with negative SPT received vaccine; those with positive SPT had vaccine administration deferred in most cases. Clinical and laboratory profiles were obtained to include asthma history, presence of other food allergy, and level of egg specific IgE. ELISA was conducted on selected vaccine lots to determine ovalbumin concentration. RESULTS: Clinical history of egg allergy ranged from eczema to wheezing. 45/55 patients had asthma and 52/55 had other food allergy. 32/55(58%) had negative SPT and 23/55(42%) had positive SPT. All 32 patients who were SPT negative to vaccine were immunized with 4 patients developing mild localized cutaneous reactions and 1 patient developing mild wheezing. Of the 23 patients who were SPT positive to vaccine 5 were immunized and none developed reactions. Detected ovalbumin concentration in three vaccine lots ranged from 4.9 ug/mL to 14.6 ug/mL. CONCLUSIONS: In our study patients with egg allergy were safely immunized with influenza vaccine. Current recommendations for influenza vaccine and egg allergy remain the safest and most reliable approach to administration (Zeiger RS. Current issues with influenza vaccination in egg allergy. JACI 2002;110:830-40).

Effect of H2O−CO2 Organization on Ovalbumin Adsorption at the Supercritical CO2−Water Interface

We have studied the formation of water-CO(2) interfaces in the presence of different concentrations of ovalbumin (OVA) by tensiometry and by means of interfacial rheological measurements to obtain some information on the capacity of protein film to stabilize H(2)O in CO(2) emulsion. The formation of pure water-CO(2) interface can be described as a two-step phenomenon.(1) The CO(2) molecules adsorb onto the water surface and then a reorganization of the interface creates a H(2)O-CO(2) cluster network. This organization occurs at a temperature (40 degrees C) higher than the higher temperature limit (10 degrees C) allowing the formation of crystalline structure called CO(2) clathrate.(2) Our results show that ovalbumin adsorption from bulk concentrations higher than 0.0229 g/L inhibits the cluster formation for a CO(2) pressure less than 80 bar. However, for lower concentrations, the more the CO(2) pressure is close to 80 bar, the more OVA adsorption is reduced by the H(2)O-CO(2) cluster network. Moreover, from a pressure of 90 bar, the affinity of OVA for the interface increases and mixed films made of protein molecules and clusters are obtained for the OVA concentrations lower than 1 g/L.

Oral Administration of Freeze-Dried Kefir Reduces Intestinal Permeation of and Oral Sensitization to Ovalbumin in Mice

An increase in plasma ovalbumin concentrations after intragastric administration of ovalbumin was suppressed by concomitant freeze-dried kefir in BALB/c mice. Serum levels of ovalbumin-specific immunoglobulin G and proliferation of splenic mononuclear cells in mice immunized orally with ovalbumin were suppressed by feeding freeze-dried kefir. We propose that kefir reduces intestinal permeation of food antigen, which contributes to suppression of oral sensitization.

Isolation of tryptophan as an inhibitor of ovalbumin permeation and analysis of its suppressive effect on oral sensitization.

Tryptophan was isolated from rat feces as an active compound against ovalbumin permeation in an in vitro Caco-2 cell model. Tryptophan dose-dependently inhibited ovalbumin permeation with accompanying increase in transepithelial electric resistance, and its inhibitory activity reached a plateau at 10 mM. Brown Norway rats were sensitized by intragastric administration of ovalbumin together with or without tryptophan. Antibody levels specific to ovalbumin in the sera and proliferative responses of spleen mononuclear cells to ovalbumin were significantly lower in rats administered ovalbumin plus tryptophan than those administered ovalbumin alone. These results suggest that tryptophan suppresses oral sensitization to ovalbumin, probably via suppression of ovalbumin absorption from the intestinal tract.

Evaluation of protein allergenic potential in mice: dose-response analyses.

With the increasing interest in novel foods derived from transgenic crop plants, there is a growing need for the development of approaches for the characterization of the allergenic potential of proteins. Whereas immunogenicity is a common property of foreign proteins, including food proteins, relatively few are significant dietary allergens with the inherent capacity to provoke IgE antibody production and immediate-type hypersensitivity responses. In order to evaluate an approach for the measurement of the allergenic potential of proteins, detailed dose-response analyses of humoral immune responses induced following systemic exposure of BALB/c strain mice to proteins known to differ in terms of sensitizing activity have been conducted. Mice were exposed to a range of concentrations of ovalbumin, a major allergenic constituent of hen's egg, a purified peanut allergen, Arachis hypogea agglutinin, or to the milk allergen bovine serum albumin, and to materials considered to lack significant allergenicity: a crude potato protein extract and a purified potato protein, potato agglutinin. The specific IgE antibody was measured by homologous passive cutaneous anaphylaxis assay, and the specific IgG antibody was measured by enzyme-linked immunosorbent assay. Each of the five proteins was immunogenic in mice, inducing IgG antibody responses at all doses tested, although there was some variation with respect to the vigour of IgG responses. Marked differences in the capacity of these proteins to induce IgE responses were observed, however, with relatively high-titre IgE antibody provoked by all three allergens over the dose ranges examined, whereas the potato proteins stimulated low-titre IgE antibody at the highest dose (10%) only. Importantly, differences in IgE antibody production have been observed against a background of equivalent immunogenicity (IgG antibody responses). The data presented here suggest that the measurement of antibody (IgE) responses in BALB/c mice appears to identify allergens accurately and to distinguish them from those materials that apparently lack allergenicity.

Irreversible self-assembly of ovalbumin into fibrils and the resulting network rheology

The self-assembly of ovalbumin into fibrils and resulting network properties were investigated at pH 2, as a function of ionic strength. Using transmission electron microscopy (TEM), the effect of ovalbumin concentration on the contour length was determined. The contour length was increasing with increasing ovalbumin concentration. TEM micrographs were made to investigate the effect of ionic strength on the contour length. In the measured ionic strength regime (0.01–0.035 M) fibrils of approximately equal length (±200 nm) were observed. TEM micrographs showed that the contour length of the fibrils, versus time after dilution, remained constant, which indicates that the self-assembly of ovalbumin is irreversible. Using the results of rheological measurements, we observed a decreasing critical percolation concentration with increasing ionic strength. We explain this result in terms of an adjusted random contact model for charged semiflexible fibrils. Hereby, this model has now been proven to be valid for fibril networks of β-lg, BSA and, currently, for ovalbumin.

Effect of enzymatic modification of dietary wheat flour for reducing its allergenicity on oral sensitization to and intestinal absorption of ovalbumin.

Increase in plasma immunoglobulin G specific to orally administered ovalbumin in Brown Norway rats was retarded by feeding enzyme-treated wheat flour when compared with untreated flour. Because plasma ovalbumin concentrations after feeding ovalbumin tended to be lower in mice fed enzyme-treated flour than in those fed untreated flour, suppression of ovalbumin absorption may be relevant to retarded sensitization observed in rats.

FlgM gains structure in living cells.

Intrinsically disordered proteins such as FlgM play important roles in biology, but little is known about their structure in cells. We use NMR to show that FlgM gains structure inside living Escherichia coli cells and under physiologically relevant conditions in vitro, i.e., in solutions containing high concentrations (>/=400 g/liter) of glucose, BSA, or ovalbumin. Structure formation represents solute-induced changes in the equilibrium between the structured and disordered forms of FlgM. The results provide insight into how the environment of intrinsically disordered proteins could dictate their structure and, in turn, emphasize the relevance of studying proteins in living cells and in vitro under physiologically realistic conditions.

An active compound against allergen absorption in hypoallergenic wheat flour produced by enzymatic modification.

Hypoallergenic wheat flour produced by modification with cellulase and actinase showed inhibitory activity against ovalbumin permeation in an in vitro model by using the Caco-2 cell monolayer. The activity was found in the cellulase preparation used for producing the flour. An active compound was isolated by HPLC and identified as Trp-Ser-Asn-Ser-Gly-Asn-Phe-Val-Gly-Gly-Lys by 1H-NMR data and Edman degradation. The undecapeptide, some oligopeptides with the N-terminal sequences and Trp ethyl ester showed activity at 10(-7) M, acetyl Trp being active at 10(-2) M. These data suggest that the Trp residue without a free carboxyl group would be required for the inhibitory activity of ovalbumin absorption through the intestinal tract.

A kinetic study of the mechanism of radiation induced agglomeration of ovalbumin in aqueous solution

The effect of concentration on the protein radiolytic damage resulting in a change in molecular mass was measured in the concentration range from 0.2 to 2mmol×dm−3 ovalbumin in phosphate buffered solutions saturated with N2O. The electrophoretic analysis of samples on discontinuous SDS-polyacrylamide gels in the presence or absence of 5% β-mercaptoethanol showed an expected result, i.e. that the protein scission did not take place in the absence of oxygen. Only ovalbumin agglomerates, bonded by covalent bonds other than S–S bridges, were observed. The G-value for the formation of ovalbumin agglomerates increased linearly from 1.1 to 2.4 by increasing the ovalbumin concentration from 0.2 to 2mmol×dm−3. The result is interpreted as to be owing to the competition between ovalbumin agglomeration and some intramolecular reactions which did not lead to the change in the molecular mass. It was also found that the G-value is independent of irradiation dose rate. The result was rationalized as a kinetic evidence that the agglomeration is not a cross-linking process, i.e. it does not occur via recombination of the protein radicals produced in the interaction of ovalbumin and OH radical. The result suggested that the agglomeration takes place via the process of grafting, i.e. it occurs in the reaction of ovalbumin radical and an intact ovalbumin molecule. The time-resolved light scattering experiments provided an additional proof, supporting the reaction scheme of radiation-induced protein agglomeration. The biological consequences of the proposed mechanism of protein agglomeration are also discussed.

Isotropic Force Percolation in Protein Gels

We have determined elasticity data of various ovalbumin gels as a function of concentration of ovalbumin and analyzed these data in terms of a percolation model. In addition, we have analyzed elasticity data of a multitude of other protein gels. We find that all data can be described by one percolation model. The critical exponent is 1.79 ± 0.25, in accordance with isotropic percolation. The value of the critical percolation threshold varies by an order of magnitude. The findings suggest that the effects of external fields on gelation can be captured by the effects of these external fields on the critical percolation threshold.

The Inhaled Administration of KF19514, a Phosphodiesterase 4 and 1 Inhibitor, Prevents Antigen-induced Lung Inflammation in Guinea Pigs

We examined in this study the effect of KF19514, a phosphodiesterase 4 and 1 inhibitor, on antigen-induced lung inflammation by inhaled administration in guinea-pigs. It was previously reported that inhaled KF19514 prevented antigen-induced bronchoconstriction and platelet-activating factor (PAF)-induced lung inflammation. In fact, a variety of factors other than PAF are related to lung inflammation in real subjects with asthma. Guinea-pigs were actively sensitized by exposure to ovalbumin (OA). Fifteen to 20 days later, the guinea pigs were challenged by exposure to aerosols of five successively increasing concentrations of OA (0.01, 0.1, 0.5, 1 and 5 mg/ml). Bronchoalveolar lavages (BALs) were performed 24 h after the antigen challenge, and airway hyperresponsiveness to acetylcholine (ACh) was studied 24 h after the challenge by measuring lung resistance and dynamic compliance. Ovalbumin antigen challenge produced a marked and significant eosinophil accumulation in the BAL fluids and airway hyperresponsiveness to ACh 24 h after the challenge. Inhaled KF19514 (0.01–0.1%) inhibited the eosinophil accumulation significantly and dose-dependently but inhaled rolipram (0.01–0.1%) and aminophylline (0.1–1%) did not. In addition, the development of airway hyperresponsiveness was prevented by inhaled KF19514 (0.01%) but not by inhaled rolipram (0.01%) and aminophylline (0.1%). Based on these data, KF19514 was suggested to be a promising drug in the treatment of asthma by local administration to the lung.

OVALBUMIN AEROALLERGEN EXPOSURE-RESPONSE IN BROWN NORWAY RATS

A major route of exposure to allergens is through the respiratory tract. Comparatively few animal studies have used aerosolized high-molecular-weight allergens for sensitization, and in these studies, proper characterization of the aeroallergen exposure was usually missing. The purpose of this study was to profile the exposure-response relationship in Brown Norway rats (BNR) to well-characterized ovalbumin (OVA) aerosols. Rats were exposed 30 min/wk 6 wk to respirable OVA aerosols from <1 mg/m3 to 64 mg/ m3 air. Ovalbumin-specific circulating immunoglobulin (Ig)E, IgG, and IgA were measured throughout the study period. Rats were sacrificed 1 day after the last exposure. Pulmonary tissue was processed for histopathological and histochemical analysis. Tracheas were isolated, perfused, and assessed for in vitro responsiveness to methacholine. Serum concentrations of OVA-specific antibodies increased with both exposure concentration and number of exposures. The number of BNR with measurable titers also increased with both dose and time. Pulmonary inflammatory changes were noted only in BNR exposed to higher OVA concentrations (15 and 64 mg/m3 air). Increased tracheal reactivity to methacholine was not found in any of the sensitized BNR. In summary, sustained aeroallergen concentration-dependent changes in specific antibody responses and pulmonary inflammation have been demonstrated. and enhance IgE production in the Brown Norway rat (BNR) al., 1997). Similar discrepancies have been reported with airway Airway reactivity following repeated exposure of the BNR been reported to increase (Elwood et al., 1991) and also to be (Kips et al., 1992). The state of allergic pulmonary inflammation