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T Virtanen

Publications and source records attributed to T Virtanen.

At least 19 recordsLinked to original sources
PubMed2007

Development of antioxidant activity in milk whey during fermentation with lactic acid bacteria.

AIMS: To investigate the production of antioxidant activity during fermentation with commonly used dairy starter cultures. Moreover, to study the development of antioxidant activity during fermentation, and the connection to proteolysis and bacterial growth. METHODS AND RESULTS: Antioxidant activity was measured by analysing the radical scavenging activity using a spectrophotometric decolorization assay and lipid peroxidation inhibition was assayed using liposomal model system with a fluorescence method. Milk was fermented with 25 lactic acid bacterial (LAB) strains, and from these six strains, exhibiting the highest radical scavenging activity was selected for further investigation. Leuconostoc mesenteroides ssp. cremoris strains, Lactobacillus jensenii (ATCC 25258) and Lactobacillus acidophilus (ATCC 4356) showed the highest activity with both the methods used. However, the radical scavenging activity was stronger than lipid peroxidation inhibition activity. The development of radical scavenging activity was connected to proteolysis with four strains. Molecular distribution profiles showed that fermentates with high scavenging activity also possessed a higher proportion of peptides in the molecular mass range of 4-20 kDa, while others had mostly large polypeptides and compounds below 4 kDa. In addition, the amount of hydrophobic amino acids was higher in these fermentates. CONCLUSIONS: The development of antioxidant activity was strain-specific characteristic. The development of radical scavengers was more connected to the simultaneous development of proteolysis whereas, lipid peroxidation inhibitory activity was related to bacterial growth. However, high radical scavenging activity was not directly connected to the high degree of proteolysis. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge, this seems to be the first report, which screens possible antioxidant activity among most common dairy LAB strains. Use of such strains improve nutritional value of fermented dairy products.

Amino Acids↗
PubMed2005

The DR4-DQ8 haplotype and a specific T cell receptor Vbeta T cell subset are associated with absence of allergy to Can f 1.

BACKGROUND: The significance of specific T cell receptor (TCR) Vbeta subtypes and human leucocyte antigen (HLA) class II alleles for the development of allergy to lipocalin allergens such as the major dog allergen Can f 1 is not clear at present. OBJECTIVE: To characterize the TCR Vbeta usage in the Can f 1-specific T cell lines and the HLA class II genotypes of Can f 1-allergic and non-allergic subjects. METHODS: T cell lines were induced with recombinant Can f 1 from the peripheral blood mononuclear cells of 12 non-atopic dog owners and 26 dog-allergic patients. Thirteen of the dog-allergic subjects were sensitized to Can f 1. Expression of the TCR Vbeta subtypes on CD4(+) T cells in the T cell lines was measured by flow cytometry. The subjects were HLA genotyped for DRB1, DQB1 and DPB1 loci. RESULTS: Can f 1-specific T cell lines were obtained from 18 subjects, with either positive (n=8) or negative (n=10) skin prick tests (SPTs) to recombinant Can f 1. The frequency of TCR Vbeta5.1(+) T cells was significantly higher in the T cell lines of subjects with negative SPTs to the allergen. Moreover, DR4-DQ8 haplotype was over-represented among these subjects. CONCLUSION: The DR4-DQ8 haplotype and the TCR Vbeta5.1(+) CD4(+) T cells may be protective against allergy to Can f 1.

Allergens↗
PubMed2004

Psoriasin, a calcium-binding protein with chemotactic properties is present in the third trimester amniotic fluid.

Psoriasin is a small calcium-binding protein first found in psoriatic lesions and also up-regulated in other inflammatory skin diseases and cancer tissues. Psoriasin is also present in the fetal epithelial cells. Its biological function is unclear, but there is both in vitro and in vivo evidence for its chemokine-like activity. The aim of the present study was to find whether psoriasin could be found in the amniotic fluid and thus could have long-range immunobiological effects. Two recombinant psoriasins were prepared, one in Escherichia coli, the other one in Pichia pastoris. The former was used to produce a rabbit antiserum against psoriasin. Fractionation of full-term amniotic fluids with polyacrylamide gel electrophoresis (PAGE) and gel filtration associated with immunodetection with the antiserum were used to identify a protein compatible with the size of psoriasin. The identity of psoriasin was further verified by mass spectrometric analysis. Expression of psoriasin in cells of the amniotic membranes was detected with nested RT-PCR. Because of its chemokine-like activity, psoriasin present in the amniotic fluid might have consequential immunobiological effects during the fetal development.

Amnion↗
PubMed2004

Assessment of recombinant dog allergens Can f 1 and Can f 2 for the diagnosis of dog allergy.

BACKGROUND: The use of recombinant allergens for the diagnosis and immunotherapy of allergy may offer several advantages over allergen extracts. OBJECTIVE: To produce recombinant dog allergens Can f 1 and Can f 2 in Pichia pastoris yeast and to assess their suitability for the diagnosis of dog allergy. METHODS: Clinically diagnosed dog-allergic patients' and healthy non-atopic dog owners' reactivities against recombinant Can f 1 and Can f 2 and commercial dog epithelial extract were studied by a panel of methods including skin prick test (SPT), ELISA and IgE immunoblotting. RESULTS: Recombinant Can f 1 and Can f 2 were found immunologically functional: they bound dog-allergic patients' IgE in immunoblotting and inhibited specifically the binding of IgE to their natural counterparts in the dog allergen extract. Moreover, patients' IgE reactivity in immunoblotting to natural Can f 1 and their SPT with the recombinant allergen were perfectly concordant (phi coefficient 1.0, P<0.001). The concordance was slightly lower with recombinant Can f 2 (phi coefficient 0.92, P<0.001). A lower number of dog-allergic patients, 52%, reacted against Can f 1 than previously reported. About one-third of the patients reacted to Can f 2. In immunoblotting, the highest prevalence of reactivity, 60%, was directed to an 18 kDa component. Aminoterminal sequencing showed this to be a previously unidentified allergenic protein. CONCLUSIONS: The recombinant allergens can be used reliably to identify Can f 1 and Can f 2-sensitized individuals. However, the two allergens are insufficient as reagents for diagnosing dog allergy.

Adult↗
PubMed2003

Probing the mechanisms of low immunogenicity of a lipocalin allergen, Bos d 2, in a mouse model.

BACKGROUND: Bos d 2, a major bovine allergen of the lipocalin family, stimulates very weakly cow dust-asthmatic subjects' peripheral blood mononuclear cells and the spleen cells of several inbred mouse strains immunized with the allergen. OBJECTIVE: To identify the immune mechanisms accounting for the weak stimulatory capacity of Bos d 2. METHODS: The spleen cell responses of BALB/c mice immunized with the allergen and with hen egg lysozyme and tetanus toxoid as control antigens were examined using several in vitro methods. RESULTS: Analysis of the numbers of spleen cells in the antigen-stimulated in vitro cultures with the vital dye 7-amino-actinomycin D showed that Bos d 2 induced a smaller expansion of cells in comparison with the control antigens. Increased cell death in vitro did not account for the weak response against Bos d 2. The number of spleen cells reacting against Bos d 2 also proved to be the lowest when they were analysed by labelling the stimulated cells with 5-6-carboxyfluorescein diacetate succinimidyl ester or by enumerating cytokine-secreting cells by ELISPOT. Eliminating CD8+ cells in the in vitro culture did not enhance the response against Bos d 2. Bos d 2 was also the weakest of the antigens to stimulate the production of soluble cytokines. Adding IL-2, IL-4 or antibody against TGF-beta in the antigen-stimulated spleen cell cultures enhanced the proliferative responses against all the antigens, whereas adding IL-12 or antibody against IL-4 or IL-10 did not enhance the responses. CONCLUSION: The results exclude several mechanisms of peripheral tolerance as an explanation for the poor immune response against Bos d 2, and suggest that the allergen is recognized by a low number of specific T cells. The weak immunogenicity of Bos d 2 may be related to its allergenicity.

Allergens↗
PubMed2002

Threshold levels of purified natural Bos d 2 for inducing bronchial airway response in asthmatic patients.

BACKGROUND: Provocation tests are invaluable in establishing threshold levels and a causal relationship between atopic asthma and a certain allergen source, especially in relation to work-associated exposure. Purified major allergens open possibilities for a more accurate assessment of sensitization. OBJECTIVE: To determine the threshold dose of purified major bovine dander allergen Bos d 2 in bronchial provocation in comparison with the standard allergen and a set of other parameters of allergy. METHOD: Nine consecutive patients referred to hospital for confirming the bovine origin of their occupational asthma were subjected to bronchial provocation tests with purified natural Bos d 2 and a standard bovine dander allergen. Additional tests included bronchial histamine challenge, measurements of total IgE, specific IgE antibody determinations and skin prick tests (SPT) with both allergens. RESULTS: In the provocation tests with Bos d 2, a 15% decrease in the forced expiratory volume in 1 s (FEV1) and/or peak expiratory flow (PEF) values in eight out of nine patients confirmed the predominant role of Bos d 2 in the sensitization. The threshold dose of Bos d 2 varied from 0.1 microg to > 100 microg (median +/- median absolute deviation = 4.5 +/- 3.9 microg). A positive SPT was induced by a median dose of 13.9 +/- 9.8 microg of Bos d 2. Bronchial response to histamine and IgE antibodies against Bos d 2 showed the highest correlations to the provocations results. CONCLUSIONS: The efficacy of Bos d 2 in bronchial provocation in patients with occupational cattle-associated asthma was confirmed and the range of the threshold level was determined. There were individual variations, but the response in provocation remains the reference method for identification of the cause of occupational atopic asthma. SPT and the measurement of specific IgE antibodies, preferably with purified or recombinant major allergens, increase the accuracy of the diagnosis.

Adult↗
PubMed2002

Effects of aerosols from nontoxic Stachybotrys chartarum on murine airways.

Acute effects on the upper and lower respiratory tract due to inhalation exposure to Stachybotrys chartarum (Sc) extract were investigated in mice. In addition, the capacity of the Sc exposure to activate immune system and cause inflammation in the respiratory tract was studied. The inhalation of Sc extract aerosols was observed to provoke sensory irritation in the airways of both naive and Sc-immunized mice. In contrast, exposure to aerosolized ovalbumin or phosphate buffered saline did not cause this effect. Exposure to Sc twice a week for 3 wk increased significantly the serum total immunoglobulin E (IgE) levels in BALB/c mice immunized with Sc as well as in nonimmunized mice. A slight presence of inflammatory cells was observed in the alveoli 3 days after the last exposure to Sc. In conclusion, Sc extract has the capacity to provoke sensory irritation in the murine airways and to activate the murine immune system.

Aerosols↗
PubMed2001

Two new variants of the lipocalin allergen Bos d 2.

Allergens from various sources have been shown to comprise several isoforms. In the present study, a series of chromatographic steps was carried out to separate the lipocalin allergen Bos d 2 isoforms present in cow dander. Subsequent HPLC-MS-MS analyses revealed two new Bos d 2 variants. In one of the proteins, tyrosine (Y83) was substituted by aspartic acid, and in the other protein valine (V102) was replaced by alanine. We propose the three Bos d 2 variants be named as Bos d 2.0101 (previously sequenced Bos d 2), Bos d 2.0102 and Bos d 2.0103. Our results suggest that molecular polymorphism is a common property among lipocalin allergens. Since allergen isoforms may show variation in their IgE binding and/or T-cell reactivity, all of the many allergen forms should be taken into account when planning preparations for immunotherapy.

Allergens↗
PubMed2001

Search for the determinants of allergenicity in proteins of the lipocalin family.

Three different lines of analysis have been applied to approach the problem of the allergenicity of certain proteins: biological functions, molecular structures and immunological properties. It is immediately obvious that these three are interdependent. The lipocalin family of proteins includes a significant number of allergens. A considerable amount of data is already available of lipocalins and some insights about allergenic determinants can now be presented. However, more information on the molecular structures and immunological parameters of lipocalin allergens is required.

Allergens↗
PubMed2001

Preliminary description of antigenic components characteristic of Stachybotrys chartarum.

The objective of this study was to characterize preliminarily immunogenic components characteristic of Stachybotrys chartarum to be used later for the development of a detection method for the fungus in environmental samples. The procedure for S.chartarum extract preparation was first optimized related to the age of the culture, culture type, and growth medium, and the antigenic composition of S. chartarum cultured in two different media was then characterized by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting method. Cross-reactivity of S. chartarum antigenic components with 10 other fungal species was identified by the inhibition immunoblotting method. The 10-day-old S. chartarum culture extract cultured in malt extract broth revealed a wider selection of proteins and antigenic components than the 30-day-old culture extract or the culture medium extracts. When cultured in cellulose broth, S. chartarum produced a higher number of proteins and antigenic components than in malt extract broth. The most dominant immunogenic components of S. chartarum cultured in cellulose broth were those of 65, 50, 37, and 27 kDa. The components of 65 and 50 kDa proved to be the most characteristic of this fungus according to the inhibition immunoblotting analyses. Several of the S. chartarum components were identified as glycoproteins. Carbohydrate moieties of the S. chartarum components also possessed an antibody binding activity.

Antigens, Fungal↗
PubMed2001

Lipocalin allergens.

Most animal-derived major allergens causing respiratory sensitization belong to the family of proteins called lipocalins. Their sequential identity varies but the three-dimensional structure is conserved. They are present in body fluids and secretions. Several lipocalins are able to bind and transport small hydrophobic ligands like retinol. The immunological characteristics of lipocalin allergens are poorly known. Cow dust-derived allergen, Bos d2, which is a potent inducer of IgE production, was observed to induce the weak proliferative responses of peripheral blood mononuclear cells of asthmatic patients upon stimulation in vitro. The responses were Th2-deviated and directed to a few epitopes in Bos d2. One of the epitopes, situated adjacent to a structurally conserved region of lipocalins, was recognized by the T cells of all patients. Computer predictions suggested that human endogenous lipocalins may contain epitopes in the corresponding region. We have proposed that the allergenicity of lipocalins may be associated with the adaptation of the immune system to the presence of endogenous lipocalins.

Allergens↗
PubMed2001

In vitro and in vivo responses to the recombinant bovine dander allergen Bos d 2 and its fragments.

BACKGROUND: About one in every four cases of occupational rhinitis recorded in Finland is animal-induced. Bovine allergens are the most important in this respect and the largest patient group consists of dairy farmers. Allergen immunotherapy, if proven effective, safe and feasible, would be ideal for their treatment. The development of recombinant allergens has offered new potential therapeutic prospects. Fragments of recombinant Bos domesticus (Bos d 2) allergen could be suitable for this purpose because they are recognized by T cells but their IgE-binding capacity is attenuated. OBJECTIVE: The aim of this study was to verify whether the potential of the two fragments of recombinant Bos d 2 (corresponding to amino acids 1-131 and 81-172) to induce immediate allergic reaction in a shock organ (nose) was decreased compared to the complete recombinant allergen, which would be an advantageous property for a preparation intended for allergen immunotherapy. METHODS: The study group consisted of 10 dairy farmers with cow-induced allergic rhinitis. We used the IgE titres against native Bos d 2 measured by indirect IgE ELISA to characterize the level of sensitization and compared the IgE titres in the rhinitis patients with 12 cow-sensitized asthmatic farmers and 12 healthy students. In vitro reactivity against recombinant Bos d 2 and its two fragments was studied by indirect IgE ELISA and in vivo reactivity by nasal provocation tests. RESULTS: The IgE titres against native Bos d 2 of patients with rhinitis tended to be lower than the titres of asthmatics. The healthy students did not exhibit any detectable IgE reactivity to native Bos d 2. In the patients with rhinitis, there was no statistically significant difference between IgE responses against native and recombinant Bos d 2, whereas with both in vitro and in vivo, the reactivity to both fragments of recombinant Bos d 2 was lower than the reactivity to the complete recombinant allergen. CONCLUSIONS: Due to the decreased in vivo capacity to induce immediate allergic reactions, the fragments may be better tolerated in allergen immunotherapy than the complete allergen.

Adult↗
PubMed2001

Differential effect of the alpha2-adrenoceptor antagonist, atipamezole, in limb-placing task and skilled forepaw use following experimental stroke.

PURPOSE: Tbc present study compared tbc effect of chronic administration of the selective alpha2-adrenoceptor antagonist, atipamezole, on performance in behavioral tests that differ in motoric complexity in two experimental stroke models. METHODS: Transient occlusion (120 min) of the middle cerebral artery (MCA) using the intraluminal method was used to produce corticostriatal infarcts and permanent occlusion of distal MCA by electrocoagulation was used to produce cortical infarcts. Chronic atipamezole treatment (1 mg/kg, s.c., once per day) was started 2 days after ischemia induction and continued until the end of the experiment, 35 days after ischemia induction. Behavioral performance of the operated rats was assessed 30 min after drug administration using the limb-placing test and Montoya's staircase test. RESULTS: Atipamezole facilitated spontaneous recovery in the limb-placing task particularly in rats subjected to transient MCA occlusion. The analysis of retrieved pellets in Montoya's staircase test suggests that there is no recovery (Time effect, P > 0.05) in the use of the impaired forelimb (contralateral-to-lesion) following transient MCA occlusion, whereas there was some recovery following permanent MCA occlusion (Time effect, P < 0.001). The impairment was bilateral in rats subjected to transient MCA occlusion. Atipamezole treatment did not affect the use of the impaired forelimb to retrieve pellets following transient MCA occlusion, but there was a tendency to facilitate impaired forelimb use following permanent MCA occlusion (Time*Treatment interaction, P = 0.086). CONCLUSION: Transient occlusion of the MCA produced a severe, long lasting, and bilateral deficit in skilled forelimb use. Permanent occlusion of the distal MCA was associated with less severe impairment, which was alleviated to some extent by administration of atipamezole. This is in contrast to spontaneous recovery and recovery-enhancing effects of atipamezole in the limb-placing test, particularly in the transient MCA occlusion model.

Adrenergic alpha-Antagonists↗
PubMed2000

Lipocalins as allergens.

The term allergy refers to clinical conditions caused by an inappropriate immune response to innocuous proteins in genetically predisposed persons. Allergens of animal origin are responsible for a significant proportion of allergies. In recent years, it has become evident that practically all respiratory animal allergens characterized at the molecular level belong to the lipocalin family of proteins. The current list comprises the major allergens of horse, cow, dog, mouse, rat and cockroach as well as beta-lactoglobulin of cow's milk. While the molecular structure of all these allergens is known, far less information is available regarding their immunological characteristics. Knowing the way the immune system recognizes these allergens and reacts to them might, however, be the key for discovering the common denominator of the allergenicity of lipocalins. The human body contains numerous endogenous lipocalins, and the immune system has to adapt to their presence. We have proposed that under these conditions the immune response against the lipocalin allergens which are structurally related to endogenous lipocalins might be the pathway to allergy in genetically predisposed persons. The same might well apply also to other allergens with homologous endogenous counterparts.

Allergens↗
PubMed2000

Detection of artifacts in monitored trends in intensive care.

In intensive care, decision-making is often based on trend analysis of physiological parameters. Artifact detection is a pre-requisite for interpretation of trends both for clinical and research purposes. In this study, we developed and tested three methods of artifact detection in physiological data (systolic, mean and diastolic artery and pulmonary artery pressures, central venous pressure, and peripheral temperature) using pre-filtered physiological signals (2-min median filtering) from 41 patients after cardiac surgery. These methods were: (1) the Rosner statistic; (2) slope detection with rules; and (3) comparison with a running median (median detection). After tuning the methods using data from 20 randomly chosen patients, the methods were tested using the data from the remaining patients. The results were compared with those obtained by manual identification of artifacts by three senior intensive care unit physicians. Out of an average of 22,480 data points for each variable, the three observers labelled 0.98% (220 data points) as artifacts. The inter-observer agreement was good. The average (range) sensitivity for artifact detection in all variables in the test database was 66% (33-92%) for the Rosner statistic, 64% (24-98%) for slope detection and 72% (41-98%) for median detection. All methods had a high specificity (> or = 94%). Slope detection had the highest mean positive prediction rate (53%; 21-85%). When the performance was measured by the cost function, slope detection and running median performed equally well and were superior to Rosner statistics for systemic arterial and central venous pressure and peripheral temperature. None of the methods produced acceptable results for pulmonary artery pressures. We conclude that median filtering of physiological variables is effective in removing artifacts. In post-operative cardiac surgery patients, the remaining artifacts are difficult to detect among physiological and pathophysiological changes. This makes large databases for tuning artifact algorithms mandatory. Despite these limitations, the performance of running median and slope detection were good in selected physiological variables.

Algorithms↗
PubMed2000

Epidural infusion of bupivacaine and fentanyl reduces perioperative myocardial ischaemia in elderly patients with hip fracture--a randomized controlled trial.

BACKGROUND: Perioperative myocardial ischaemia is an important risk factor for cardiac morbidity and mortality after noncardiac surgery. The impact of analgesic management on the incidence and severity of cardiac ischemia was studied in 77 elderly patients undergoing surgical treatment of traumatic hip fracture. METHODS: After hospital admission and written consent, patients were randomised to conventional analgesic regimen (intramuscular oxycodone, OPI group) or continuous epidural infusion of bupivacaine/fentanyl (EPI group). The analgesic regimens were started preoperatively. Patients were operated under spinal anaesthesia and the treatments were continued three days postoperatively. ECG was continuously recorded. ST segment depression of > or = 0.1 mV or elevation of > or = 0.2 mV lasting > or = 1 min were considered as ischaemic episodes. Nocturnal arterial oxygen saturation (SaO2) was recorded perioperatively, and subjective pain was assessed every morning using a visual analogue scale (VAS). RESULTS: Fifty-nine (OPI 30, EPI 29) patients were evaluable for efficacy. Thirteen patients (43%) in the OPI and 12 patients (41%) in the EPI group had ischaemic episodes (NS). However, significantly more patients in the OPI group had ischaemic episodes during the surgery (8 vs. 0 in the EPI group, P=0.005). The median (quartal deviation) total ischaemic burden (i.e. integral of ST-change vs. time) in patients with ischaemic episodes was ten times larger in the OPI group (340 [342] mm x min) compared with the EPI group (30 [36] mm x min) (P=0.002). There were no significant differences between the groups in average heart rates or in heart rates at the start of ischaemic episodes or in maximal heart rates during the attacks. Average nocturnal SaO2 was similar in the two groups and there were no differences in the number of hypoxaemic (SaO2<90%) episodes. Preoperatively there were no differences in subjective pain, but postoperative and average perioperative VAS scores for pain were almost 40% lower in the EPI group (P=0.006). Perioperative myocardial infarctions were not detected. CONCLUSIONS: Continuous epidural bupivacaine/fentanyl analgesic regimen, started preoperatively, reduces the amount of myocardial ischaemia in elderly patients with hip fracture.

Aged↗
PubMed1999

T cell epitopes of a lipocalin allergen colocalize with the conserved regions of the molecule.

In this study we characterized the human T cell-reactive sites of the major cow dander allergen, Bos d 2, a member of the lipocalin protein family. We showed that Bos d 2 contains only a limited number of epitopes. This is in contrast to many other allergens, which usually contain multiple T cell epitopes throughout the molecule. The epitopes of Bos d 2 were primarily concentrated in the conserved regions of the molecule. One of the epitopes was recognized by all the cow-asthmatic individuals regardless of their HLA phenotype. Computer-predicted T cell epitopes on Bos d 2, other lipocalin allergens, and human endogenous lipocalins were situated in similar locations on these molecules and corresponded to experimentally identified epitopes on Bos d 2. The results suggest that human endogenous lipocalins could be involved in the modulation of immune responses against exogenous lipocalin allergens. In addition, our findings are likely to facilitate the development of new forms of immunotherapy against allergies induced by the important group of lipocalin allergens.

Allergens↗