A technique for the isolation and purification of ommochromes (pigments of the complex eye of the adult
Hermetia illucens
fly) has been developed. Isolated ommochromes showed fluorescence with ...emission maxima at 460–470 nm and 525–535 nm, the intensity of which increased abruptly during their oxidation with hydrogen peroxide. The method of chemiluminescence quenching of luminol was used to determine the antiradical activity of ommochromes; the constant value was (1.2 ± 0.5) × 10
4
M
–1
. A finely dispersed mixture of ommochromes in 0.1 M potassium phosphate buffer (pH 7.4) containing bovine serum albumin (2.0 mg/mL) showed antimicrobial activity against
B. subtilis
ATCC 6633,
Candida albicans
ATCC 2091, and
Aspergillus niger
INA 00760. The
H. illucens
imago was concluded to be a promising renewable source of natural pigments with good antioxidant characteristics and antibacterial properties.
Today’s shortage of effective antimicrobial agents can be overcome by using antimicrobial peptides, which are produced naturally by a wide range of organisms, including microorganisms, plants, and ...mammals. Among these chemical groups, peptaibols are the well-known compounds with various biological activities, including antibacterial, antifungal, anticancer, antimycoplasmic, antitrypanosomal, and others. In this review, we summarize today’s knowledge on the sources, direct surface applications, and the mode of action of the peptaibols with anticancer and antifungal activity produced by filamentous fungi.
The ability of alkalophilic micromycetes of the species
Sodiomyces alkalinus
to produce antimicrobial compounds was studied. As a result of the determination of the spectrum and yield of antibiotic ...compounds, a promising producer of the antimycotics
Sodiomyces alkalinus
was selected from the most active strains 8KS17-10. The producer exhibited antifungal activity against opportunistic fungi, as well as pathogenic clinical isolates of molds and yeasts—pathogens of systemic mycoses. The isolated active compound can be attributed to the group of antimicrobial glycopeptides based on the totality of the identified structural features (molecular weight, absorption ratio at certain wavelengths).
The antimicrobial activity of the new nonribosomal peptide emericellipsin A against biofilm-forming, pathogenic, gram-positive and gram-negative clinical bacteria was studied. It was shown for the ...first time that peptides from the group of peptaibols can inhibit pathogenic forms of bacteria via their effect on biofilm formation. The most pronounced effect was demonstrated in relation to gram-positive bacteria.
The article considers stochastic mathematical models for thermolysis kinetics of complex oil-like hydrocarbon systems using mathematical statistics and the theory of random processes. Mathematical ...modeling shows that the thermolysis process is collective, nonergodic, and nonstationary. The criteria for which hydrocarbon systems obey the first order and Avrami kinetic laws are established. Using the example of thermolysis of high-viscosity Al’shacha oil, it is shown that the kinetics of the release of gaseous products of thermolysis are better described by models of stationary kinetics, and the yield of residues and distillates is better described by models of nonstationary kinetics. The established regularities can be used in modeling thermal and thermocanalytic processes of petrochemistry and oil refining.
The concept of post-traumatic skull defect closure is based on restoration of anatomical relationships for the maximum possible recovery of brain function, i.e. it is considered as a stage of ...surgical rehabilitation. The choice of implants in pediatric patients is limited. In this regard, the «gold standard» is still autologous bone implant.
We propose a method for storage and sterilization of autologous bone implant. The last one implies keeping at a temperature of -80 ˚C with sterilization in a vacuum chamber filled with hydrogen peroxide vapors of biocidal plasma medium. Sterilization is provided by 45-minute cycle immediately before surgery. We report skull defect closure using autologous bone implants in 79 patients. Evaluation of effectiveness of storage and sterilization of autologous bone implant included analysis of mechanical properties of bone after sterilization, intra-operative microbiological monitoring, incidence of infections in early postoperative period, follow-up with assessment of resorption.
Early infectious complications occurred in 2 patients (2.5%). Complete resorption with redo surgery occurred in 6 (10.1%) cases. Sterilization in low-temperature plasma of hydrogen peroxide changes mechanical properties of the bone, increases durability under compressive stresses and decreases durability under tensile conditions. This does not affect functional tasks of autologous bone. The proposed method of storage and sterilization is accompanied by low risk of infections and resorption. Storage of autologous bone implant at a temperature of -80 ˚C with subsequent sterilization in low-temperature plasma of hydrogen peroxide can be considered as a safe and effective method for skull defect closure in children after decompressive surgery.
The continued circulation of influenza A virus subtype H5 may cause the emergence of new potential pandemic virus variants, which can be transmitted from person to person. The occurrence of such ...variants is mainly related to mutations in hemagglutinin (HA). Previously we discovered mutations in H5N1 influenza virus hemagglutinin, which contributes to virus immune evasion. The purpose of this work was to study the role of these mutations in changing other, non-antigenic properties of the virus and the possibility of their maintenance in the viral population. Mutations were introduced into the HA gene of a recombinant H5N1 influenza A virus (VNH5N1-PR8/CDC-RG) using site-specific mutagenesis. The "variant" viruses were investigated and compared with respect to replication kinetics in chicken embryos, thermostability, reproductive activity at different temperatures (33, 37 and 40°C), and virulence for mice. Amino acid substitutions I155T, K156Q, K156E+V138A, N186K led to a decrease in thermal stability, replication activity of the mutant viruses in chicken embryos, and virulence for mice, although these effects differed between the variants. The K156Q and N186K mutations reduced viral reproduction at elevated temperature (40°C). The analysis of the frequency of these mutations in natural isolates of H5N1 influenza viruses indicated that the K156E/Q and N186K mutations have little chance to gain a foothold during evolution, in contrast to the I155T mutation, which is the most responsible for antigenic drift. The A138V and N186K mutations seem to be adaptive in mammalian viruses.
—
The continued circulation of influenza A virus subtype H5 may cause the emergence of new potential pandemic virus variants, which can be transmitted from person to person. The occurrence of such ...variants is mainly related to mutations in hemagglutinin (HA). Previously we discovered mutations in H5N1 influenza virus hemagglutinin, which contributes to virus immune evasion. The purpose of this work was to study the role of these mutations in changing other, non-antigenic properties of the virus and the possibility of their maintenance in the viral population. Mutations were introduced into the
HA
gene of a recombinant H5N1 influenza A virus (VNH5N1-PR8/CDC-RG) using site-specific mutagenesis. The “variant” viruses were investigated and compared with respect to replication kinetics in chicken embryos, thermostability, reproductive activity at different temperatures (33, 37 and 40°C), and virulence for mice. Amino acid substitutions I155T, K156Q, K156E+V138A, N186K led to a decrease in thermal stability, replication activity of the mutant viruses in chicken embryos, and virulence for mice, although these effects differed between the variants. The K156Q and N186K mutations reduced viral reproduction at elevated temperature (40°C). The analysis of the frequency of these mutations in natural isolates of H5N1 influenza viruses indicated that the K156E/Q and N186K mutations have little chance to gain a foothold during evolution, in contrast to the I155T mutation, which is the most responsible for antigenic drift. The A138V and N186K mutations seem to be adaptive in mammalian viruses.
PDF
