RESUMEN

Amorphous SiO(x) thin films with three different oxygen contents (x = 1.3, 1.5, and 1.7) have been deposited by thermal evaporation of SiO in vacuum. Partial phase separation in the films has been induced by annealing at 773 or 973 K in argon for 60 and 120 min and thus Si-SiO(x) composite films have been prepared containing amorphous Si nanoparticles of various sizes (< 3 nm). Photoluminescence from the films has been measured in the temperature range 20-296 K. The single Gauss band observed in the photoluminescence spectra of the samples with x = 1.3 and centered in the range 1.55-1.75 eV has been related to radiative recombination in Si nanoparticles. Two bands, a red-orange one (related to radiative recombination in Si nanoparticles) and a green band peaked at approximately 2.3 eV (related to radiative recombination via defects) have been resolved in the photoluminescence spectra of the films with x = 1.5 and 1.7. The band in the spectra of the x = 1.3 samples has shown a relative strong thermal quenching but it is significantly weaker than the photoluminescence quenching in bulk a-Si. Besides, the higher the initial oxygen content, the weaker is the photoluminescence thermal quenching. These observations have been related to carrier confinement which is stronger in smaller nanoparticles. The thermally induced photoluminescence decrease with increasing temperature in the samples with x = 1.3 obeys the relation that is characteristic for bulk a-Si:H while the photoluminescence decrease in x = 1.5 and 1.7 samples is of Arrhenius type. We suggest that in nanoparticles larger than 2 nm recombination via band tail states is the dominating photoluminescence mechanism while in smaller nanoparticles exciton-like recombination dominates.

RESUMEN

Antibodies to a wide spectrum of infectious agents belonging to the IgA, IgM and IgG isotypes are thought to be one of the protective factors in human milk. Cow milk-fed newborns are at an increased risk of infections as well as of allergic diseases and of necrotising enterocolitis. A reasonable approach would be to add to the milk formula fed to them the immunoglobulins present in human milk. We developed a pasteurised immunoglobulin preparation from pooled donor plasma ('Orabulin') containing 75% IgG, 18% IgA and 6% IgM for feeding to high-risk bottle-fed babies. Its molecular composition was studied by HPLC and by SDS-PAGE. The levels of IgA, IgG and IgM antibodies in Orabulin were compared to these in the immunoglobulin fraction of human colostrum and an enrichment was found. It is suggested that the presence of a standardised amount of human IgM in an immunoglobulin preparation intended for feeding to newborns may bring an additional advantage because of the high opsonising and virus-neutralising activity of the antibodies of this isotype.

Asunto(s)

RESUMEN

The beneficial effect of intravenous immunoglobulin (IVIg) therapy in patients with autoimmune diseases is at least partially dependent on the content in IVIg of antibodies capable of interacting with variable regions (idiotypes) of autoantibodies. In the present study, we have evaluated the antibody activity to a panel of self and environmental antigens of IVIg preparations and their dimer-enriched fractions. Dimers were either obtained by affinity chromatography of IVIg on Sepharose-bound F(ab')2 fragments of IVIg or by size exclusion gel filtration chromatography of IVIg. Enrichment of IVIg in dimers was found to be associated with an increase in the antibody activity against self-antigens as compared with unchromatographed IVIg. Our findings extend previous observations on enhanced autoantibody content of the affinity chromatography-separated 'connected' fraction of IVIg and suggest that therapeutic preparations of IVIg enriched in dimers may be obtained by size exclusion chromatography. Separation by size increases the feasibility of industrial-scale preparation of IVIg with high dimer content that are endowed with high potential immunomodulatory activity in vivo.

Asunto(s)

RESUMEN

The levels of IgG subclasses were determined, by radial immunodiffusion using monoclonal antibodies, in 16 production batches of two human immunoglobulin preparations for intravenous use--Immunovenin and Immunovenin-intact. While the partially degraded preparation--Immunovenin contained exclusively IgG1, the subclass distribution in Immunovenin-intact was close to that observed in normal human serum.

Asunto(s)

Asunto(s)

RESUMEN

The protective effect of two different human immunoglobulin preparations for intravenous use and one specific staphylococcal immunoglobulin for intramuscular application were compared in mice infected with the capsular Staphylococcus aureus Smith strain. Immunovenin is produced by partial fragmentation of IgG with plasmin; it contains about 60% intact IgG and 40% Fab and Fc fragments. Immunovenin-intact is produced by a polyethylene glycol (mol wt 6000) fractionation method followed by ion exchange chromatography and contains more than 95% intact IgG molecules. A specific staphylococcal immunoglobulin is obtained by a rivanol/ethanol fractionation method from selected sera with high anti-alpha toxin level. All three types of immunoglobulins induced similar degree of protection when their effect was determined as activity (ED50) per gram immunoglobulin.

Asunto(s)

RESUMEN

Comparative investigations were carried out on the antibody level in test animals--sheep, vaccinated with a polyvaccine against C and D enterotoxemia and necrotic hepatitis as well as in combined application with Levamisol. It was found that with the use of the preparation the stimulation of immunogenesis with type D and necrotic hepatitis--type B antigens (included in the composition of the polyvaccine) was enhanced. No stimulation of immunogenesis with the type C specific antigen was found within the period of investigation. Immunity was better built up when the animals were treated with the combined product as compared with the controls, given the polyvaccine without Levamisol.

Asunto(s)

RESUMEN

Investigations in vitro were carried out to overcome the drug resistance of transconjugants of Escherichia coli with resistance to neomycin, kanamycin, chloramphenicol, and tetracycline. Use was made of zinkbacitracin Pharmachim . It was found that in conc. of 32 gammas /cm3 zinkbacitracin the elimination of resistance, on an average, to neomycin is 34.9%, to kanamycin - 27.1%, to chloramphenicol - 42.4%, and to tetracycline - 24.9%. With the transconjugants treated with a higher concentration of 64 gammas /cm3 the figures were 42.8%, 34.5%, 46.2%, and 32.4%, respectively. The conclusion is made that zinkbacitracin Pharmachim is effective in eliminating the resistance of E. coli to the antibiotics in the experiment. The higher the concentration used the higher the percent of resistance climination .

Asunto(s)

RESUMEN

Studied were a total of 143 strains of Escherichia coli, isolated from birds affected with coli septicaemia, with special reference to the presence of conjugative R-plasmids. It was found that 57 of the strains could not be tested on E. coli C-600, and the carrying of R-plasmids with the remaining 86 strains reached 65.11 per cent. The markers of kanamycin, sulphatiazol, and neomycin were transmitted in a highest percent (63.95, 53.47, and 45.43, respectively). The level of the resistance transferred proved close or comparable to that of the field strains. It was concluded that the conjugative R-plasmids were widely occurring with Escherichia coli strains that were pathogenic for birds. This should be taken into consideration when using chemotherapeutic agents with birds.

Asunto(s)

RESUMEN

Studied was the sensitivity to chemotherapeutic agents of a total of 49 strains of Escherichia coli isolated from the various compartments of industrial pig-breeding complexes. It was found that most of the strains were sensitive, however, there were also strains that showed multi-drug resistance. Conjugation tests revealed that in 30.6 per cent of the cases such resistance was induced by conjugative R-plasmids. It was also found that the presence of R-plasmids among bacteria in the indifferent environment' at the pig-breeding complexes was of great importance for chemotherapeutic treatments in connection with the selective capacity of the preparations applied.

Asunto(s)

RESUMEN

The methods of diffusion and serum dilutions in solid nutrient media were employed to study the drug resistance of a total of 71 Escherichia coli strains isolated from anal samples of clinically normal pigs. It was found that an essential number of the strains were resistant to penicillin, erythromycin, tetracycline, kanamycin, neomycin, chloramphenicol, oleandomycin, tylan, oxacilin, and sulfathiazol. The testing of the these strains through conjugation with E. coli C-600 as a recipient showed that 38.23 per cent of them were carriers of conjugative R-plasmids. It was concluded that the occurrence of conjugative R-plasmids in Escherichia coli isolated from normal pigs was considerable and could constitute an unsurmountable problem in the chemotherapy of such animals affected with colibacteriosis. On the other hand, the presence of R-plasmids in the microflora of clinically normal pigs could be referred to as a permanent source of drug resistance.

Asunto(s)

RESUMEN

Studied was the sensitivity of a total of 143 strains of Escherichia coli, isolated from young birds and broilers died from coli septicaemia, to antibiotics and chemotherapeutics. The following descending order was established: gentamycin, carbenicillin, ampicillin, furazolidon, borgal, kanamycin, strep tomycin, chloramphenicol, neomycin sulphathiazole, and tetracycline. Markers of resistance were established with all strains with regard to the therapeutic agents in current and prospective use in industrial poultry farming. It is stated that a preliminary antibiogram is indispensable in order to obtain dependable results in the treatment of animals affected with colibacteriosis. An alternative is to apply directly those drugs to which the strains have shown highest sensitivity.

Asunto(s)

RESUMEN

A study on the effect of various neutralizers of the most widely spread means of disinfection applied in animal rearing was made. For that purpose twin lecytine was tested for quadruple ammonium compounds: twin--for phenolic compounds, natrium thiosulfate--for iodoformium and chlor-containing compounds, as well as natrium sulfite--for formalin. As test micro-organisms were used Staph. aureus Sg 511, E. coli 078, and Ps. aeruginosa. The investigations were performed after the suspension method with dilutions in geometrical progressions. It was established that for the disinfection by quadruple ammonium compounds 3% twin-80 plus 0.3% lecytine is suitable as neutralizer. In disinfection with phenolic compounds the 1% twin-80 solution gives good results. As neutralizer of formalin disinfection 2% natrium sulfite solution can be successfully used. For iodoformium disinfection or disinfection with chlor-containing compounds good neutralizing effect can be achieved by 1% solution of natrium thiosulfate.

Asunto(s)

RESUMEN

Anti-microbial activity and pharmokinetics of erythromycin aspartate "Pharmachim" (EA) in chickens was studied. The investigations included erythromycin thiocyanat (ET) of the company Abbott-USA (the preparation Gallimycin poultry formula). The studies revealed that EA has an effect on Gram-positive microorganisms mainly. It is quickly resorbed by the digestive tract and following the administration of 50 and 100 mg/kg body weight (applied by tube) in doses of 0.14 to 0.8 meg/cm3 it can be detected in the blood serum of chickens after 10 min only have elapsed. Maximal concentrations (from 0.35 to 0.95 meg/cm3) are discovered at about the 30-60th min and after that EA levels are gradually reduced to traces or 0.125 mcg/cm3 by 24th h. Application via drinking water in a dose of 115 mg/l results in EA quantities of 0.11 to 0.2 meg/cm3 detected in the blood during the entire course of treatment with therapeutic water. The use of equal ET doses results in 20 to 39% lower antibiotic levels. The same is true for EA and ET content in organs and tissues. Both preparations are eliminated by the bile secretion untill the 96th h post treatment's end. Resorption of EA is quick and high grade following muscular injection and at a dose of 20 mg/kg body weight the antibiotic persists in bacteriostatic concentrations in the blood up to the 15th, while at a dose of 40 mg/kg body weight-up to the 24th h post its single application.

Asunto(s)

RESUMEN

Studies are the following preparations, produced by "PHARMACHIM": tylosine-base (Tylosine-50), tylosine tartarate (Tylosine pulvis) and tylosine phosphate (substance and granules) and their analogues: tylosine-base (Tylan-50), tylosine tartarate (Tylan soluble) and tylosine phosphate (Tylan AF 99), produced by the "Elanco" Company. The biological activity of the preparation was determined by means of the microbiological method of diffusion in agar. In the case of all experimental treatments, the preparations were compared in conformity with their biological activity expressed in IU/mg of the preparations. The minimum inhibition concentrations of the preparations were determined by the method of serial dilutions in liquid nutritive media on 19 different pathogenic strains. The antispirochetal activity of the preparations compared was tested on 130 cockerels and pullets, experimentally infected with Borrelia anserina of the Surnevo and Pamoukchii serotypes. The application of the preparations started simultaneously with the infection or 24 and 48 hrs after it and continued for days. No significant differences are found in the antibacterial and antispirochetal activities of the Bulgarian tylosine preparations and those manufactured by the "Elanko" Company. The tylosine base does not differ significantly in its antimicrobial and antispirochetal activities from the tylosine phosphate and the tylosine tartarate when equal in IU concentrations and doses are applied.

Asunto(s)

Asunto(s)

Asunto(s)