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Biomedical subjects

G Kostov

Publications and source records attributed to G Kostov.

At least 19 recordsLinked to original sources
PubMed1996

Thermal stability of calf skin collagen type I in salt solutions.

The thermal stability of acid-soluble collagen type I from calf skin in salt solutions is studied by high-sensitivity differential scanning calorimetry. Three concentration ranges have been clearly distinguished in the dependence of collagen thermal stability on ion concentration. At concentrations below 20 mM, all studied salts reduce the temperature of collagen denaturation with a factor of about 0.2 degree C per 1 mM. This effect is attributed to screening of electrostatic interactions leading to collagen stabilisation. At higher concentrations, roughly in the range 20-500 mM, the different salts either slightly stabilise or further destabilise the collagen molecule in salt-specific way that correlates with their position in the lyotropic series. The effect of anions is dominating and follows the order H2PO4- > or = SO4(2-) > Cl- > SCN-, with sign inversion at about SO4(2-). This effect, generally known as the Hofmeister effect, is associated with indirect protein-salt interactions exerted via competition for water molecules between ions and the protein surface. At still higher salt concentrations (onset concentrations between 200 and 800 mM for the different salts), the temperature of collagen denaturation and solution opacity markedly increase for all studied salts due to protein salting out and aggregation. The ability of salts to salt out collagen also correlates with their position in the lyotropic series and increases for chaotropic ions. The SO4(2-) anions interact specifically with collagen - they induce splitting of the protein denaturation peak into two components in the range 100-150 mM Na2SO4 and 300-750 mM Li2SO4. The variations of the collagen denaturation enthalpy at low and intermediate salt concentrations are consistent with a weak linear increase of the enthalpy with denaturation temperature. Its derivative, d(delta H)/dT, is approximately equal to the independently measured difference in the heat capacities of the denatured and native states, delta Cp = Cp(D) - Cp(N) approximately 0.1 cal.g-1 K-1.

Animals↗
PubMed1985

[Effect of levamisole on white mice and on the immunological reactivity of guinea pigs].

Investigations were carried out on the protective action of therapeutic doses of levamisole (Pharmachim) on mice with a LD100 Salmonella gallinarum infection. Studied was also the effect of levamisole on the immunologic response of guinea pigs infected with Salmonella cholerae suis. It was found that therapeutic amounts of 3 mg/kg levamisole applied to mice following respective patterns protected them against a lethal dose of S. gallinarum. The animals showed enhanced resistance to the infection--20 to 50 per cent of them survived as against 100 per cent mortality with the controls. The guinea pigs showed upon treatment with levamisole certain changes with some of the factors of unspecific response--enhanced phagocytic and lysozyme activity as judged by the development of infection with a S. cholerae suis culture. At the same time the agglutinin titer that substantiated the immunologic response was negligibly changed as compared to the controls. On the base of the results obtained an attempt was made to elucidate the mechanism of the protective action of levamisole.

Agglutinins↗
PubMed1983

[Erythrocyte antigen for the rapid intravital diagnosis of fowl typhoid and pullorum disease].

A stable erythrocyte antigen was obtained for the rapid diagnosis of typhoid and pullorum disease in birds, which was tested under laboratory and field conditions. It was found that with the use of whole blood or serum taken from birds that had been either experimentally infected or had died of spontaneous infection of Salmonella gallinarum and Salmonella enteritidis the erythrocyte antigen was substantially superior to the routinely used colour ordinary test-antigen in terms of time consumed, intensity, and number of reacting birds. Discussed is the effect of its quick adoption into practice on the basis of its higher epizootiologic, epidemiologic, and economic value.

Agglutination Tests↗
PubMed1981

[Macrophage "disappearance" from the peritoneal cavity as affected by a specific antigen].

Investigations were carried out into the effect of a specific antigen on the changes in the macrophage count in the peritoneal exudate of guinea pigs sensibilized with a live Salmonella abortus ovis culture, with and without an allergic reaction of a delayed type. The setting in of the allergic response was shown to correlate with the decrease in the number of macrophages--in animals with a positive response there was a strong drop of the macrophage count in the peritoneal exudate. It is stated that the changes observed in the number of these cells are directly associated with the dose used: they are more strongly manifested when larger amounts of the S. abortus ovis antigen are used.

Animals↗
PubMed1981

[Trails with levamisole to stimulate immunity against Newcastle disease in poultry].

Attempts to stimulate the immunity against Newcastle disease in birds aged 2 months, of the Leghorn breed, were carried out. It was found that levamisol at the rate of 3 mg/kg body weight given once, parenterally, 24 hours prior to or after the immunization of the birds with a live La Sota vaccine or given three times, parenterally or orally, did not stimulate the humoral immune response. No differences were found in the level of the total protein, protein fractions, and the titer of the hemagglutinating antibodies between the test and the control birds. There was, however, prolongation of the time of effective immunity in the levamisol-treated and vaccinated birds as against the birds that were vaccinated against Newcastle disease only. Discussed in the possible mechanism of stimulating the immunity with levamisol.

Animals↗
PubMed1981

[Characteristics of a Salmonella abortus ovis allergen].

Studies were carried out to obtain an allergen of Salmonella abortus ovis and establish its chemical composition and diagnostic value with guinea pigs and sheep infected with the same causative agent. It was found that the allergen produced contained a great amount of protein (75 per cent), an essentially low amount of sugars (11 per cent), and a negligible amount of total phosphorus (0.85 per cent). It was also established that the allergen did not induce the production of antibodies in rabbits following intravenous inoculation, and did not give any positive allergic reaction in normal guinea pigs after intradermal application. It was shown to have a high diagnostic value, detecting some 87 per cent of the infected guinea pigs and 85 per cent of the infected sheep. The allergen also showed high specificity - it did not induce a positive skin reaction in guinea pigs infected with Y. enterocoli type 9, E. coli, and S. cholerae suis.

Allergens↗
PubMed1980

[Diagnostic value of the protein antigens of Br. abortus and Yersinia enterocolitica type 9].

Protein antigens were obtained from Br. abortus 99 and Yersinia enterocolitica, type 9, and were titered on guinea-pigs infected with a living culture from these microbes. It was proved that the guinea-pigs infected with Yersinia reacted with a skin-allergic reaction only to an antigen obtained from Yersinia and not from Brucella. Conversely, the animals infected with Br. abortus B-19 reacted during skin treatment only to an allergen from Brucella, but not with an allergen from Yersinia. In a rabbit anti-yersinia serum were proved precipitins through the immunodiffusion test against the protein allergen from Yersinia, whereas no Brucella precipitins were detected with a protein allergen. In anti-Brucella rabbit serum (Brucella amboceptor or agglutinative serum, no precipitins were proved with Brucella and Yersinia protein allergens. In a hiperimmune rabbit serum against Brucella and Yersinia were proved precipitins against a polysaccharide both from Yersinia and Brucella. It was adopted that protein antigens in the case of Brucella and Yersinia were specific and that specificity could be used for differentiation of these two infections.

Animals↗
PubMed1979

[Effect of cortisome on monocyte "disappearance" from the blood].

The effect of cortisone on monocyte "disappearance" from peripheral blood of guinea pigs sensibilized with live S. abortus ovis culture and showing positive skin-allergic reaction with allergen of the same salmonella was studied. It was established that in case cortisone is applied in a dose of 22 mg per guinea pig intramusculary 3 or 1 h before or simultaneously with intravenous injection of homologous allergen, it blocks the allergen's effect on monocyte "disappearance", i.e. the number or monocytes in cortisone treated animals does not change, while their number in the control animals (not treated with cortisone) decreases considerably. The possible blocking effect mechanisms of cortisone on the specific allergen action are discussed.

Allergens↗
PubMed1979

[Comparative immunological studies and the determination of the epizootiological effectiveness of Soviet vaccine LTF-130 in trichophytosis].

The immunological response of calves vaccinated against herpes is explained and the epizootic effectiveness of the Soviet vaccine ltf 130 applied in Bulgaria is assessed. The antigenic relation of the vaccine's strain with the agent causing herpes in Bulgaria was revealed by parallel investigation on serum RCB of calves suffering from herpes and of calves vaccinated with ltf 130. The immunological response was assessed by proving the existence of complement binding antibodies. It was found that vaccinated calves react by producing complement binding antibodies up to the 45th day post immunization. During the 1976-1978 year period 62 121 calves and heifers were treated for medicative purposes and 653 666 calves and heifers--for prophylactic purposes. From all vaccine treated animals 95.4-98.8% recovered. No cases of herpes were observed in animals vaccinated prophylactically.

Animals↗
PubMed1978

[Diagnostic value of agglutination reaction with buffered Brucella antigen stained with rose bengal].

A specific buffered antigen has been obtained, employing a method developed by the authors, stained with Bengal rose and intended for performing a fast agglutination reaction to confirm brucellosis. The antigen produces a clear and demonstrative agglutination reaction with positive sera. Practically, the test is readily carried out, and can be made a routine both in every serologic laboratory and for investigations under field conditions. The reaction produced with this antigen can determine dependably the epizootic status on a farm or in the herd. The diagnostic value of the antigen is essential, especially with swine. Besides, it shows a wide a diagnostic scope for brucellosis with all species of animals (97--98 per cent).

Agglutination Tests↗
PubMed1978

[Effect of aflatoxin on the serum profile and antibody formation in chickens].

Experiments were carried out to follow up the effect of aflatoxin on the production of hemagglutinating antibodies in birds vaccinated against Newcastle disease and the changes in the serum profile. Birds that had been given a feed mixture with 560 and 640 mcg per kg for 20 days showed a lower titer of hemagglutinating antibodies and a drop of the alpha1, alpha2, beta1, gamma2-globulin fractions as well as a rise of the albumin and gamma1-globulin fractions. The liver and kidneys of the treated birds showed dystrophic changes.

Aflatoxins↗
PubMed1978

[Allergen effect on the number of monocytes in guinea pigs].

Followed up are the changes in the number of monocytes under the effect of venal injection of an allergen from Salmonella abortus ovis to guinea pigs, sensibilized by live and killed cultures of the same Salmonella. After inoculation of healthy guinea pigs with a live culture, the number of monocytes doubles and remains at this level up to the 11th day after the infection. The killed culture of this Salmonella does not possess a similar action. A venal injection of Salmonella abortus ovis allergen to sensibilized guinea pigs, possessing a dermal-allergic reaction, leads to a marked decrease in the number of monocytes in the blood on the 2nd and 6th hrs after application of the allergen, while on the 24th h their number regains the level prior injection. The "disappearance" of monocytes from the peripheral blood is antigen-specific and the assumption is made that it is the result of the synthesis of the migration-inhibition factor in blood circulation at the contact of the sensibilized "T" lymphocytes with the specific antigen.

Allergens↗
PubMed1977

[Allergic reactions in guinea pigs infected with Yersinia enterocolitica type 9 relative to homologous (Yersinia) and heterologous (Brucella) allergens].

Obtained were allergens from Brucella abortus 99 and Yersinia enterocolitica Type 9 through hydrolysis with hydrochloric acid after M. M. Ivanov and with acetic acid after Kirzhaev. They were tested on guinea pigs that were infected with Yersinia enterocolitica Type 9 through different ways. To M. M. Ivanov's allergens all infected animals responded pronouncedly in the case of the homologous allergen, and half of them only and to a lower degree in the case of the heterologous Brucella allergen. To Kirzhaev's allergens the infected guinea pigs showed more strongly expressed skin reactions. In this case, too, the response was stronger to the homologous Yersinai allergen. The diameters of skin swelling were more than twice greater than with the use of the heterologous Brucella allergen, and the sum of the reacting skin sites was five times greater in the case of the homologous Yersinia allergen. No essential differences were observed between the oral and the plantar route of infection combined with the subcutaneous injection of carboneum tetrachloratum and the morphine preparation Omnopon.

Allergens↗
PubMed1977

[Differentiation of non-specific positive brucellosis reactions using an antigen stained with rose bengal].

A Brucella buffered antigen, stained with Bengal rose by a method of the authors, was obtained. It showed a high distinguishing capacity with regard to the nonspecific agglutinations after Huddleson and Wright at a negative complement-fixation test for brucellosis with sera from cattle, pigs, sheep, and horses. Such differentiation, however, proved to be incomplete and for sera of different animals varied within the range of 34 to 0.0 per cent.

Agglutination Tests↗
PubMed1977

[Transmission of a delayed allergic reaction to Salmonella abortus-ovis via the blood plasma of gamma-irradiated guinea pigs].

Use was made of blood plasma taken from guinea pigs (sensibilized with a live culture of Salmonella abortus ovis and then irradiated wiht 800 rad gamma-rays) to transmit the skin allergy reaction to normal, nonsensibilized guinea pigs. The allergy reaction was demonstrated in the recipients of plasma as early as the 3-4th hour following the injection of the allergen into the skin. It reached its peak at the 12-24th hour and later on strongly diminished, remaining in few of the animals only up to the 48th hour. The infiltrate at the site of injection in the skin of positively reacting animals contained at the 24th hour cells of the polymorphonuclear type which predominated, while the cells of the mononuclear type were few in number. There were no precipitins in the plasma of the donors, and the titer of the agglutinins and the cytophile antibodies was very low. Regardless of these findings it was concluded that the transmitted allergy reaction was of the fast type (after Arthuss), and not of the delayed one.

Agglutinins↗