The use of maize haploidy inducers as a tool in agricultural plant biotechnology.

The discovery of the ability of some mutations to stimulate haploidy during hybridization made it possible to create one of the most promising and sought-after trends in the f ield of reproductive biology. Haploid inducers created on their basis are capable of increasing the frequency of haploidy up to 15 %. The improvement of the existing haploid inducer lines and the search for new genes that contribute to a high frequency of haploidy are underway. Along with these studies, the f ield of application of haploid inducers in genetics and plant breeding is expanding. Haploid inducers carrying R1-nj genes for anthocyanin pigmentation of the seed and embryo are able not only to mark the hybrid embryo and identify haploid genotypes, but also to detect genes that suppress the anthocyanin color of the grain, like C1-I, C2-Idf, and In1-D. Depending on their quantity, the phenotypic manifestation of the gene in the seed varies. Haploidy is widely used for accelerating hybrid breeding and obtaining both new maize lines with improved traits and their sterile counterparts. By introducing certain genes into the genome of the improved line, breeders can use the doubled haploid (DH) breeding technology to accelerate the creation of pure lines carrying the desired gene. Haploid inducer maize lines and their tetraploid analogs are used in the selection of rediploid maize lines by their resynthesis from tetraploid genotypes. In 2019, Syngenta Company synthesized a haploid inducer maize line carrying a CRISPR/cas construct capable of simultaneously stimulating haploidy and editing the genome at a specif ied DNA site. Thanks to this technology, it became possible to improve haploid inducers by introducing various CRISPR/cas constructs into the haploid inducer genome for editing any DNA site. Maize haploid inducers are widely used in doubled haploid wheat breeding. The f irst experiments showed that the most effective haploid inducer for stimulating haploidy in wheat is maize pollen. Researchers are intensively searching for other ways of using maize haploid inducers in plant breeding.

[Dyssynergic defecation is one of the causes of chronic constipation].

AIM: To define the rate and type distribution of dyssynergic defecation (DD) in patients with primary chronic constipation (CC) and to evaluate the efficiency of biofeedback (BFB) therapy. SUBJECTS AND METHODS: One hundred and thirty-two 18-to-89-year-old patients treated in the Moscow Clinical Research and Practical Center for primary CC were examined using proctological examination, colonofibroscopy, anorectal manometry (ARM), and the balloon expulsion test. RESULTS: Different types of DD were identified in 44.69% of the patients. Defecation disorder type 1 was prevalent (in 64.4% of the patients with DD). The positive result of BFB therapy was noted in the patients with DD and fecal incontinence. CONCLUSION: The timely detection of functional defecation disorders can recover the lost function of pelvic floor muscles by BFB therapy and exclude the uncontrolled patient use of laxatives.

Relationship between osteogenic characteristics of bone marrow cells and calcium phosphate surface relief and solubility.

The capacity of mouse bone marrow cells to adhere to calcium phosphate surfaces and form tissue plates depending on the surface relief and solubility was studied in ectopic bone formation test. Calcium phosphate coating of titanium disks, made by the anodic spark (microarch) oxidation in 10% orthophosphoric acid with hydroxyl apatite particles, differed by the structure (thickness of coating, size of pores, and roughness) and solubility (level of in vitro oxidation of 1-week extracts of implants). Chemical (phasic and element) composition of the studied calcium phosphate coatings was virtually the same. The findings indicate that histogenesis is regulated by physicochemical characteristics of the implant surface. It seems that the osteogenic potential of calcium phosphate surfaces is largely determined by their relief, but not by pH of degradation products.

Osteogenic potential of mesenchymal stem cells from bone marrow in situ: role of physicochemical properties of artificial surfaces.

Correlation analysis demonstrated the role of inorganic parameters of the surfaces of calcium phosphate materials in the regulation of osteogenic differentiation of mesenchymal precursors. The progenitor stromal cells were isolated from syngeneic bone marrow immobilized in vitro on calcium phosphate surfaces with different structure, phasic, and elemental composition. After 45 days of subcutaneous ectopic osteogenesis in BALB/c mice, the tissues grown on these matrixes were characterized histologically. It was found that adhesion of bone marrow cells is the initial stage determining their future proliferation (conduction) over the artificial surface and the area of formed tissue plate. The success of histogenesis depends on surface roughness. The optimal roughness class was 4-5 (Russian State Standards), which enables differentiation of progenitor stromal cells under the specific microenvironmental conditions into the connective and adipose tissue cells. Differentiation of the progenitor cells into the stromal cells producing the hemopoiesis-inducing microenvironment also takes place in the foci of active hemopoiesis. Induction of osteogenic potential of the stromal precursors (osteoinduction) is determined by the ratio between calcium and phosphate atoms in surface coatings. In our experimental system, osteogenic differentiation of stromal mechanocytes was blocked only at Ca/P<0.5.

[Errors and complications of total endoprosthesis of the knee joint with the prostheses "Waldemar Link"].

The article presents results of an analysis of errors and complications for total endoprosthesing different pathological states of the knee joint with prostheses "Waldemar Link". The causes of early and late complications were found. The authors have developed original means for prevention and treatment of them. The most acceptable conclusion was the recommendation to observe the principles of active surgical strategy and using the means of complex conservative therapy at different periods of rehabilitation of the patients.

In vitro regulation of cell behavior by calcium phosphates synthesized by the mechanochemical method.

Biological activity of eight hydroxyapatite powders synthesized by the mechanochemical method was studied in vitro. Introduction of copper and zinc atoms into synthetic hydroxyapatite structure promotes cell adhesion. Hydroxyapatites obtained by the mechanochemical method are promising base for a new class of materials and coatings with regulated bioactivity for orthopedics and traumatology.

Adhesion of Staphylococcus aureus to implants with different physicochemical characteristics.

Adhesion of pathogenic Staphylococcus aureus (strain 209) to BT1-0 titanium disks (12 mm in diameter) with different coatings and noncoated was studied in vitro by photocolorimetry. Transparency of bacterial suspension in normal saline was evaluated after 2-h culturing with the implants at 37 degrees C. The decrease of S. aureus content in the suspension due to its adsorption on implants was negligible and increased by 0.9-5.5% in comparison with the control (adhesion to glass). When the specimens were placed into bacterial suspension, the density of staphylococcal adsorption on the surface considerably increased (by 9-53%) in comparison with the control, which attested to active participation of the implants in bacterial adsorption. The degree of bacterial adhesion to the implants decreased in the following order: disk with calcium phosphate ceramic coating-disk with calcium phosphate X-ray amorphous coating-disk without coating-disk with cermet coating. The adhesion of Staphylococcus is a stochastic process depending on the sum of implant characteristics, in particular, on the phase composition of the coating, electric conductivity, and Ca/P ionic ratio. The authors conclude that the formation of antibacterial properties of coating by saturating them with antibiotics or impregnation with metals, specifically silver ion implantation, is justified, because it reduces the postimplantation infection risk.