SEARCH · PubMed Health

Results for “LACTOGLOBULINS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

PubMed1991

Antibody-dependent cell-mediated cytotoxicity to beta-lactoglobulin-coated cells with sera from children with intolerance of cow's milk protein.

The capacity of serum antibodies against beta-lactoglobulin to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) was analysed in sera from children with cow's milk protein intolerance (CMPI). The children with CMPI were divided into three groups according to clinical features: delayed-onset CMPI with gastrointestinal symptoms (n = 8); immediate-onset CMPI with gastrointestinal and skin symptoms (n = 8); and immediate-onset CMPI with skin symptoms only (n = 8). The CMPI groups were compared with children with untreated (n = 9) or treated (n = 8) coeliac disease and a control group (n = 22). Sera from the children were examined for cytotoxic effects using lymphocytes from healthy adults as effector cells and radiolabelled beta-lactoglobulin-coated erythrocytes from the same donor as target cells. In addition, IgG and IgA serum antibodies against beta-lactoglobulin were determined with ELISA. Sera from children with CMPI and gastrointestinal symptomatology showed a significantly increased capacity to induce ADCC reactivity as compared with controls. This increased capacity was seen in sera from those with immediate as well as delayed onset of the gastrointestinal symptoms. In contrast, sera from children who had an immediate-onset CMPI with only skin symptoms mediated no such increase in ADCC reactivity. Moreover, children with coeliac disease with a few exceptions, demonstrated low ADCC reactivity, despite the fact that they had high levels of antibodies against beta-lactoglobulin. ADCC may be an immunopathogenic mechanism in certain cases of CMPI with gastrointestinal symptoms.

Antibodies↗

PubMed1995

ADCC-mediating capacity in children with cow's milk protein intolerance in relation to IgG subclass profile of serum antibodies to beta-lactoglobulin.

In a previous study sera from children with cow's milk protein intolerance (CMPI) exhibiting gastrointestinal symptoms were found to efficiently induce antibody-dependent cell-mediated cytotoxicity (ADCC) to beta-lactoglobulin-coated cells. In contrast, sera from children with coeliac disease showed a low ADCC-mediating capacity, despite high levels of IgG anti-beta-lactoglobulin antibodies. The study described here was undertaken to evaluate whether differences in IgG subclass profile of anti-beta-lactoglobulin antibodies could explain the observed variations in the ADCC-mediating capacity. Forty-eight sera from the following groups of children were investigated: CMPI with predominantly gastrointestinal symptoms, CMPI with skin symptoms of immediate-onset, children with untreated coeliac disease and healthy references. Absorption experiments indicated that primarily IgG1 antibodies were responsible for the ADCC-mediating capacity of the sera. Accordingly, the ADCC reactivity of individual sera correlated with their IgG1 antibody levels. Sera from CMPI children with gastrointestinal symptoms, most of which had a high ADCC reactivity, also demonstrated a distinctive subclass pattern of their anti-beta-lactoglobulin antibodies with higher relative proportions of IgG1 (ratios: IgG1/IgG, IgG1/IgG3 and IgG1/IgG4) than those from the other diagnostic groups. Using logistic regression analysis, the diagnostic potential of ADCC as well as of different IgG subclass variables for the recognition of gastrointestinal symptoms caused by CMPI was evaluated. The ADCC reactivity of sera was found to be the best predictor in this model.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1994

A model for the denaturation and aggregation of beta-lactoglobulin.

A quantitatively correct kinetic model for the temperature-induced denaturation and aggregation of beta-lactoglobulin is presented. The model recognizes an initiation, a propagation and a termination step by analogy with polymer radical chemistry. The decrease in native beta-lactoglobulin is predicted to follow order 3/2, in agreement with experimental results. The size of the protein polymer particles is predicted to be proportional to the square root of the initial beta-lactoglobulin concentration. The scattered light intensity is proportional to the product of concentration and size of the protein polymer particles. The initial increase in scattering intensity of the particles therefore scales with the initial squared beta-lactoglobulin concentration. The influence of other reaction conditions, e.g. ionic strength and pH, can be incorporated via the reaction constants of the reaction kinetic pathway.

Electrophoresis, Polyacrylamide Gel↗

PubMed1996

Modifications occur at different structural levels during the heat denaturation of beta-lactoglobulin.

Heat-induced modifications in the tertiary and quaternary structure of beta-lactoglobulin were followed at neutral pH for the protein at high temperature and for the protein that was heated and cooled. Fast changes in the environment of aromatic amino acids were apparent from near-ultraviolet-CD spectra of the heated protein and their intensity increased with increasing temperature. These modifications were irreversible only at temperatures higher than 65-70 degrees C. Addition of iodoacetamide during the heating/cooling cycle greatly reduced the extent of irreversible modification of the tertiary structure of the protein. Reaction of the native beta-lactoglobulin dimer with iodoacetamide or dithiobis(2-nitrobenzoic acid) was only observed upon heating at temperatures higher than 40 degrees C and resulted in progressive reaction of the unique sulfhydryl group in each of the two protein monomers. The sulfhydryl reagents induced release of a monomeric protein species that was no longer able to aggregate to the native dimeric form or to sequentially form polymers as found in the protein after heating at high temperature. Dimer dissociation was identified as the rate-limiting step in the reaction of beta-lactoglobulin with sulfhydryl reagents. It occurred at temperatures much lower than those required for appreciable modification of the tertiary structure of the protein, and had an extremely high activation energy (Ea = 213 kJ/mol). These results are compared with other published data, and a general mechanism for the formation of early reactive species in heat-treated beta-lactoglobulin at neutral pH is proposed which stresses the relevant role of a highly hydrophobic, molten-globule-like free monomer that has an exposed sulfhydryl group on its surface.

Circular Dichroism↗

PubMed2004

Conformational changes of beta-lactoglobulin in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles. A fluorescence and CD study.

The effect of beta-lactoglobulin encapsulation in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles on the environment of protein and on Trp was analysed at different water contents (omega0). CD data underlined the distortion of the beta-sheet and a less constrained tertiary structure as the omega0 increased, in agreement with a concomitant red shift and a decrease in the signal intensity obtained in steady-state fluorescence measurements. Fluorescence lifetimes, evaluated by biexponential analysis, were tau1 = 1.28 ns and tau2 = 3.36 ns in neutral water. In reverse micelles, decay-associated spectra indicated the occurrence of important environmental changes associated with omega0. Bimolecular fluorescence quenching by CCl4 and acrylamide was employed to analyse alterations in the accessibility of the two Trp residues in beta-lactoglobulin, induced by changes in omega0. The average bimolecular quenching constant was found not to depend on omega0, confirming the insolubility of this quencher in the aqueous interface, while increases with omega0. The drastic decrease with omega0 of kq, associated with the longest lifetime kq2(CCl4), comparatively to the increase of kq2(acrylamide), emphasizes the location of beta-lactoglobulin in the aqueous interfacial region especially at omega0> or = 10. The fact that (omega0 = 30) >> kq2(acrylamide) (water) also confirms the important conformational changes of encapsulated beta-lactoglobulin.

Acrylamide↗

PubMed1985

Homology of beta-lactoglobulin, serum retinol-binding protein, and protein HC.

The milk protein beta-lactoglobulin has been extensively studied but its function has not been identified. A clue regarding the function of a protein can be obtained by discovering a genetic relationship with a protein of known function through comparisons of amino acid sequence. Such comparisons revealed that beta-lactoglobulin is similar to human serum retinol-binding protein and to another human protein of unknown function known as complex-forming glycoprotein heterogeneous in charge (protein HC). beta-Lactoglobulins from several species have been found to bind retinol, while the absorption and fluorescence properties reported for the unidentified heterogeneous prosthetic group of protein HC are retinoid-like. The role of serum retinol-binding protein in vitamin A transport in the circulation suggests that the other two homologous proteins may function in the binding and transport of retinoids; beta-lactoglobulin may facilitate the absorption of vitamin A from milk and protein HC may mediate the excretion of retinol-derived metabolites.

Alpha-Globulins↗

PubMed2006

Genotyping of beta-lactoglobulin gene by PCR-RFLP in Sahiwal and Tharparkar cattle breeds.

BACKGROUND: Improvement of efficiency and economic returns is an important goal in dairy farming, as in any agricultural enterprise. The primary goal of dairy industry has been to identify an efficient and economical way of increasing milk production and its constituents without increasing the size of the dairy herd. Selection of animals with desirable genotypes and mating them to produce the next generation has been the basis of livestock improvement and this would continue to remain the same in the coming years. The use of polymorphic genes as detectable molecular markers is a promising alternative to the current methods of trait selection once these genes are proven to be associated with traits of interest in animals. The point mutations in exon IV of bovine beta-Lactoglobulin gene determine two allelic variants A and B. These variants were distinguished by Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP) analysis in two indigenous Bos indicus breeds viz. Sahiwal and Tharparkar cattle. DNA samples (228 in Sahiwal and 86 in Tharparkar) were analyzed for allelic variants of beta-Lactoglobulin gene. Polymorphism was detected by digestion of PCR amplified products with Hae III enzyme, and separation on 12% non-denaturing gels and resolved by silver staining. RESULTS: The allele B of beta-Lactoglobulin occurred at a higher frequency than the allele A in both Sahiwal and Tharparkar breeds. The genotypic frequencies of AA, AB, and BB in Sahiwal and Tharparkar breeds were 0.031, 0.276, 0.693 and 0.023, 0.733, 0.244 respectively. Frequencies of A and B alleles were 0.17 and 0.83, and 0.39 and 0.61 in Sahiwal and Tharparkar breeds respectively. The Chi-square test results (at one degree of freedom at one per cent level) revealed that the Tharparkar population was not in Hardy-Weinberg equilibrium as there was a continuous migration of animals in the herd studied, where as, the results are not significant for the Sahiwal population. CONCLUSION: Genotype frequencies of AA were the lowest compared to that of BB genotype in Sahiwal cattle while AB genotypes were more frequent in Tharparkar cattle. The frequency of A allele was found to be lower than that of B allele in both the breeds studied. These results further confirm that Bos indicus cattle are predominantly of beta-Lactoglobulin B type than Bos taurus breeds.

Alleles↗

PubMed1988

Molecular cloning of bovine beta-lactoglobulin cDNA.

A cDNA library from bovine mammary gland mRNA was constructed in pBR322 and screened by hybrid-selected translation and immunoscreening. Several beta-lactoglobulin clones were identified and sequenced. All clones contained cDNA fragments corresponding to the 3' region of beta-lactoglobulin mRNA. The 3' non-translated region of beta-lactoglobulin mRNA consists of 187 nucleotides; the polyadenylation signal AATAAA occurs 17 nucleotides before the poly(A) tail. The amino-acid sequence predicted from the 3' coding region corresponds completely to the previously determined amino-acid sequence of beta-lactoglobulin.

Amino Acid Sequence↗

PubMed1990

Antibodies raised against bovine beta-lactoglobulin react with beta 2-microglobulin. A possible antigenic region at beta-LG positions 124-140.

beta-Lactoglobulin is a major whey protein in bovine milk. Its presence has been demonstrated in all mammals examined except rodents and humans. However a positive cross reaction was observed for human milk proteins with antibodies raised against bovine beta-lactoglobulin. We isolated and characterized a protein fraction of ca. 12 kDa responsible for the positive cross reaction. N-terminal sequencing and amino-acid analysis indicated that this protein is identical with human beta 2-microglobulin. We observed structural homology between beta-lactoglobulin region 124-140 and beta 2-microglobulin 71-86, which suggested that positions 124-140 could be the antigenic region for beta-lactoglobulin. Six highly conserved amino-acid residues are suggested as candidates for the antigenic site.

Amino Acid Sequence↗

PubMed1991

A marsupial beta-lactoglobulin gene: characterization and prolactin-dependent expression.

Analysis of the tammar wallaby beta-lactoglobulin cDNA and inferred amino acid sequences reveal extensive sequence divergence from the eutherian beta-lactoglobulins. Conserved residues include the cysteines and a number of individual amino acids involved in structure and ligand-binding. The only region of extended similarity is a heptapeptide sequence which may impart specificity to its interaction with a receptor protein. Northern analysis of total mammary RNA revealed two transcripts which result from differential utilization of polyadenylation signals. The concentration of beta-lactoglobulin mRNA increased in late lactation and correlates with increases in milk production and levels of milk fat. Quantification of beta-lactoglobulin mRNA levels in hormone-stimulated mammary gland explants from tammars in late pregnancy suggests that maximal induction of the gene is dependent on prolactin alone and that expression is not modulated by other hormones known to play a role in the initiation of lactation in eutherians.

Amino Acid Sequence↗

PubMed1993

Increased levels of cow's milk and beta-lactoglobulin antibodies in young children with newly diagnosed IDDM. The Childhood Diabetes in Finland Study Group.

OBJECTIVE: To investigate the humoral immune response to cow's milk in pediatric patients with newly diagnosed IDDM. RESEARCH DESIGN AND METHODS: We measured IgA, IgG, and IgM antibodies to the proteins of cow's milk and to beta-lactoglobulin by an enzyme-linked immunosorbent assay. Samples from 706 pediatric patients with newly diagnosed IDDM were available. We used two comparison groups: 105 patients < 7 yr old had an unrelated age-matched control subject, and samples from 456 3- to 14-yr-old nondiabetic siblings also were available. RESULTS: Patients < 3 yr of age had a markedly higher median level of IgG and IgA antibodies to cow's milk compared with the control subjects (P = 0.03 and 0.002, respectively), IgG antibodies to beta-lactoglobulin also were higher (P = 0.03). Older groups of diabetic patients, 3.0-6.9 and 7.0-14.9 yr of age, had significantly higher levels of IgA antibodies to cow's milk and beta-lactoglobulin than the age-matched comparison groups of both unrelated control subjects and nondiabetic siblings, although the median values of the diabetic patients were closer to those of the comparison groups than in the youngest groups. Nondiabetic siblings had higher levels of IgA cow's milk antibodies than unrelated control subjects of similar ages (3-6.9 yr of age) (P = 0.03). The 14 siblings contracting IDDM during the follow-up showed no change in the levels of cow's milk or beta-lactoglobulin antibodies in relation to the clinical diagnosis. CONCLUSIONS: The results indicate an abnormally strong humoral response to the proteins of cow's milk, particularly in young IDDM patients and, to a lesser extent, in their siblings. We infer that the proteins of cow's milk may trigger the autoimmune process of IDDM.

Adolescent↗

PubMed2005

The kinetics of heat-induced structural changes of beta-lactoglobulin.

Heat-induced structural changes of beta-lactoglobulin were studied at temperatures ranging from 67.5 to 82.5 degrees C, and at pH 7.5. These changes were monitored by measurement of surface hydrophobicity, thiol availability, and protein solubility. Kinetic studies were conducted to quantitatively describe the contribution of hydrophobic and SH/SS interchange reactions to the thermal structural changes of beta-lactoglobulin. Results indicate that beta-lactoglobulin is sensitive to heat-induced interchange reactions with consequences for protein solubility. The extent of changes measured by the increase in surface hydrophobicity and the decrease in slow-reacting SH groups content could be described by a first-order fractional conversion model and were characterized by activation energy values of 233.9 +/- 8.6 and 148.2 +/- 6.7 kJ/mol, respectively. The break in the Arrhenius plot suggested in literature for beta-lactoglobulin denaturation was confirmed in this study only for the kinetics of exposed SH groups.

Disulfides↗

PubMed1987

Binding of p-nitrophenyl phosphate and other aromatic compounds by beta-lactoglobulin.

Results obtained from gel filtration showed that beta-lactoglobulin binds p-nitrophenyl phosphate with a stoichiometry of 1 mol of ligand per 18,360 monomer. Circular dichroic spectra confirmed the binding and implicated tryptophan and phenylalanine residues in the interaction. Fluorescence of the protein was quenched on binding also supporting complex formation; analysis of these data indicates that p-nitrophenyl phosphate binds to beta-lactoglobulin A with a dissociation constant of 31 microM. The B and C genetic variants of beta-lactoglobulin bind p-nitrophenyl phosphate with dissociation constants of 63 and 70 microM, respectively. In addition, a series of other nitrophenyl compounds and pyridoxal phosphate were also investigated by fluorescence analysis and found to bind to the protein. These results are discussed with respect to a recent hypothesis that beta-lactoglobulin binds retinol and is structurally related to serum retinol binding protein.

Lactoglobulins↗

PubMed1993

Characteristics of beta-lactoglobulin binding to the all-trans-retinal moiety covalently immobilized on Celite.

All-trans-retinal was covalently immobilized on Celite and investigated as a bioselective adsorption matrix for beta-lactoglobulin. Two types of Celite supports were compared, indicating the best performance with 100/120 mesh, type R648. The R648 matrix yielded a high concentration (9.2 mumol/ml) of the ligand when the derivative was produced, and the derivatized matrix exhibited the best retention of beta-lactoglobulin. Binding of beta-lactoglobulin to the immobilized trans-retinal matrix is biospecific, but the affinity is dependent on pH and ionic strength. alpha-Lactalbumin is not bound to this bioselective adsorbant, so its elution was not retarded or affected by pH or buffer concentration. Affinity for beta-lactoglobulin was optimal at pH 5.14; a dissociation constant of 2.7 microM was obtained in .1 M buffer solutions. At pH 7.0, the affinity decreased 44-fold, and, below pH 3.5, no binding occurred. The estimated loading capacity based on chromatographic data was approximately 14 g/L (.75 mumol/ml) of support.

Adsorption↗

PubMed1983

Gelation of the complex between kappa-casein and beta-lactoglobulin.

The gelation of the complex between kappa-casein and beta-lactoglobulin was examined. The apparent viscosity of the mixture of kappa-casein and beta-lactoglobulin increased by heat treatment. The mixture formed a gel at the concentration of 8% (w/w). The gel formation was accelerated by the chymosin treatment. The mixture of kappa-casein and beta-lactoglobulin in each concentration of 1.5% gelled by the addition of chymosin after heat treatment. Forming the complex between kappa-casein and beta-lactoglobulin was necessary to the gel formation. Therefore, heat treatment of above 70 degrees C was demanded. Turbidity increased and the relative content of soluble protein decreased accompanied with gel formation. The addition of calcium ion to the heated solution produced an increase in turbidity. The larger the protein concentration was, the larger the breaking stress of the formed gel was. The addition of calcium ion weakened the breaking stress of the gel.

Calcium↗

PubMedDate not supplied

[Comparison of two methods to determine beta-lactoglobulin antibodies in children with cow's milk protein intolerance].

In the last years the evaluation of IgG against beta-lactoglobulin (beta LG-IgG) has been proposed as reliable test to diagnose Cow's Milk Protein Intolerance (CMPI). This test, associated with other diagnostic tools (such as eosinophilia, hemoccult, RAST, challenge, etc.) showed a good sensibility, but less specificity. In fact antibodies against beta-lactoglobulin were found in other gastrointestinal diseases (coeliac disease, inflammatory bowel diseases, cystic fibrosis, etc.). To determine the specificity of the test some Authors attributed great importance to the laboratory method (IFL, ELISA). They retained IFL more specific. In order to verify the behaviour of the two methods and their concordance we carried out a double bind determination of IgG against beta-lactoglobulin (beta LG-IgG) on serum samples from children affected by CMPI. For this study we chose 16 children, aged from 3 months and 6 years, suffering from CMPI of which 11 with gastrointestinal complaints and 5 from extraintestinal ones. All children were diagnosed on the basis of the following criteria: clinical picture, blood eosinophilia, positivity of hemoccult, amelioration after the withdrawal of cow's milk proteins from the diet, positivity of challenge test. All children at the time of the assessment assuming a diet containing cow's milk proteins. beta LG-IgG were measured using simultaneously immunofluorescent and micro-ELISA methods. The obtained data showed that 12 children (75%) had IgG versus beta-lactoglobulin in the serum. This result was obtained both with IFL and ELISA methods, showing a 100% of concordance.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗

PubMedDate not supplied

[Changes in the immunochemical properties of beta-lactoglobulin during proteolysis and exposure to various physico-chemical factors].

Heating of cow milk beta-lactoglobulin at 96 degrees, pH 8.0 led to the protein aggregation because of intermolecular disulfide exchange as shown by agarose gel immunoelectrophoresis, where additional precipitation strips were detected. At the same time, there was not observed dissociation of beta-lactoglobulin into separate fractions after proteolysis or denaturation in 8 M urea. beta-Lactoglobulin, its thermoaggregated and S-carboxymethyl denaturated forms exhibited similar anaphylactic effect on sensitized guinea pigs. Allergenic properties of beta-lactoglobulin appears to be unaltered in food hydrolyzates after thermal treatment and limited proteolysis.

Animals↗

PubMed1977

[Results of the study of preventive effectiveness and side effects of anti-influenza lactoglobulin in controlled epidemiologic trial].

Prophylactic activity and side action of antiinfluenza lactoglobulin were studied under conditions of controlled epidemiological trial in 6361 persons during the epidemiological rise of influenza incidence. The data obtained pointed to the absence of any protective effect of antiinfluenza lactoglobulin. Marked allergenic properties of lactoglobulin and development of sensitization in the persons under observation were found during the study of the side-effect of the preparation. Thus, the absence of prophylactic efficacy and the sensitizing action of antiinfluenza lactoglobulin pointed to the inexpediency of its use for prophylactic and therapeutic purpose.

Clinical Trials as Topic↗