The specialist in regeneration-the Axolotl-a suitable model to study bone healing?

While the axolotl's ability to completely regenerate amputated limbs is well known and studied, the mechanism of axolotl bone fracture healing remains poorly understood. One reason might be the lack of a standardized fracture fixation in axolotl. We present a surgical technique to stabilize the osteotomized axolotl femur with a fixator plate and compare it to a non-stabilized osteotomy and to limb amputation. The healing outcome was evaluated 3 weeks, 3, 6 and 9 months post-surgery by microcomputer tomography, histology and immunohistochemistry. Plate-fixated femurs regained bone integrity more efficiently in comparison to the non-fixated osteotomized bone, where larger callus formed, possibly to compensate for the bone fragment misalignment. The healing of a non-critical osteotomy in axolotl was incomplete after 9 months, while amputated limbs efficiently restored bone length and structure. In axolotl amputated limbs, plate-fixated and non-fixated fractures, we observed accumulation of PCNA+ proliferating cells at 3 weeks post-injury similar to mouse. Additionally, as in mouse, SOX9-expressing cells appeared in the early phase of fracture healing and amputated limb regeneration in axolotl, preceding cartilage formation. This implicates endochondral ossification to be the probable mechanism of bone healing in axolotls. Altogether, the surgery with a standardized fixation technique demonstrated here allows for controlled axolotl bone healing experiments, facilitating their comparison to mammals (mice).

[Laboratory methods for measuring adhesive bond strength between restoration materials and hard tooth tissues]. / Laboratornye metody ispytaniya adgezionnoi prochnosti soedinenii restavratsionnykh materialov s tverdymi tkanyami zuba.

THE AIM OF THE STUDY: Was to review laboratory methods measuring the bond strength of adhesive dental materials to hard tooth tissues. The paper points out the impact of test conditions on the measured strength of adhesive bond to dentine and enamel. Various in vitro studies are discussed, including the analyses of fracture surfaces and test-induced stresses. These studies are found to be helpful to identify particularities, advantages, and limitations of each approach. We present a systematic picture of available bond-strength data aimed at revealing general trends in adhesive performance. No clear superiority of any particular method for determining the bond strength between restoration materials and tooth tissues can be identified on the basis of reviewed literature. Therefore, no single universal approach can be at present proposed for determining the strength of adhesive bond.

Immunomodulatory effects of progesterone and selective ligands of membrane progesterone receptors.

Progesterone (P4) and its analogues regulate various reproductive processes, such as ovulation, implantation, pregnancy maintenance and delivery. In these processes, an important role is played by the immune cells recruited to the female reproductive organs and tissues, where they are exposed to the action of P4. Progestins regulate cellular processes, acting through nuclear steroid receptors (nSRs), membrane P4 receptors (mPRs), and through the sensors. It remains unclear, what type of receptors is used by P4 and its derivatives to exert their effect on the immune cells and how similar their effects are in different types of these cells. We have previously synthesized new progesterone derivatives, among which two selective mPRs ligands, not interacting with nSRs were identified. The objective of this study was to examine the effects of P4 and new selective mPRs ligands on the expression of pro- and anti-inflammatory cytokines in activated human peripheral blood mononuclear cells (PBMCs), THP-1 monocyte cells, and Jurkat T cells. It was demonstrated that the action of P4 and selective ligands was unidirectional, but in different types of the immune cells, their effects were different, and sometimes even opposite. In PBMCs, exposure to these steroids resulted in the increase of mRNA and secreted protein levels of IL-1ß, TNFα, and IL-6 cytokines, as well as in the increase of INFγ mRNA level, decrease of IL-2 mRNA level, increase of TGFß mRNA level, and decrease of IL-4 mRNA and IL-10 secreted protein levels. In monocytes, similarly to PBMCs, expression of IL-1ß and TNFα mRNA was increased, but expression of IL-10 was also increased, and the TGFß expression statistically significantly remained the same. In Jurkat T cells, expression of IL-2 and TNFα mRNA decreased, while expression of IL-10 increased, and expression of TGFß did not change. Thus, progestins act on the immune cells through mPRs and have both pro- and anti-inflammatory effects, depending on the phenotypes of these cells. The data obtained are important for understanding the complexity of the immune system regulation by progestins, which depends on the type of the immune cells and individual characteristics of the immune system.

Expression of Mucins and Claudins in the Colon during Acute and Chronic Experimental Colitis.

We studied changes in the expression of mRNA for mucins and claudins in the medial part of the colon in male C57Bl/6 mice on the model of acute and chronic colitis induced by substitution of drinking water with 1% solution of dextran sodium sulphate for 5 days. In acute colitis, the expression of the main structural component of glycocalyx, mucin Muc3, decreased and expression of pore-forming claudin Cldn2 increased, which reflected enhanced permeability of tight junctions. In the chronic colitis group, in comparison with the normal group, we observed an increase in expression of mRNA of main structural mucus component Muc2, enhanced of expression of Muc1 associated with carcinogenesis, and reduced expression of Muc13, which led to a more severe course of colitis; the expression of pore-forming claudin Cldn2 was elevated. These findings indicate that the imbalance in the expression of mucins and claudins plays an important role in the mechanisms of development of acute and chronic colitis.

Agonistic and Antagonistic Effects of Progesterone Derivatives on the Transcriptional Activity of Nuclear Progesterone Receptor B in Yeast Model System.

Identification of progesterone selective agonists and antagonists that act through one of the nuclear progesterone receptor isoforms is of particular importance for the development of tissue-specific drugs in gynecology and anticancer therapy. Fourteen pregna-D'6- and pregna-D'3-pentarane progesterone derivatives with 16α,17α-cycloalkane groups and two progesterone 3-deoxyderivatives were examined for their ability to regulate transcriptional activity of human nuclear progesterone receptor isoform B (nPR-B) expressed in Saccharomyces cerevisiae yeast. Transcriptional activity of nPR-B was measured from the expression of the ß-galactosidase reporter gene with a hormone-responsible element in the promoter. Among the compounds tested, two were full progesterone agonists, four were partial agonists, one compound possessed both agonistic and antagonistic activity, one compound displayed only partial antagonistic activity, and eight compounds did not show any activity. Modifications of the pentarane structure, precisely, introduction of an additional double bound in the A or B rings and/or modification at the 6th position of progesterone, lead to a switch from the complete agonistic activity to partial agonistic or mixed activities. These modifications enable progestins to act as selective modulators of progesterone receptor. Steroids with reduced A-ring and 3-ketogroups lose their ability to regulate PR-B activity. Both 3-deoxycompounds, being selective ligands of progesterone membrane receptors, do not affect PR-B activity.

[Multi-tract percutaneous nephrolithotomy in the management of staghorn stones].

AIM: To compare the results of a single tract versus multi-tract percutaneous nephrolithotomy (PNL) MATERIALS AND METHODS: Over a period of 6 years, a total of 2,264 PNLs was performed at the N.A. Lopatkin Scientific Research Institute of Urology and Interventional Radiology, of which 875 PNLs were done for stage K3-K4 staghorn calculi. Among them, 244 (27.7%) patients underwent multi-tract PNL. We included 873 patients in our study. The median stone size was 59 (46; 88) mm. Two, three and four percutaneous tracts were used in 165 (67.6%), 63 (25.8%) and 14 (5.7%) patients, respectively. In 126 of 244 (52%) patients, a set for mini-percutaneous surgery with 14.5 and 15.5 Ch tubes was used as additional access. RESULTS: The effectiveness of single and multi-track PNL was 53.6%, and 83.8%, respectively. The mean operating time for PNL using one, two, three and four percutaneous tracts was 77.2+/-29.9, 85.7+/-26.9, 116.6+/-28, and 144.0+/-12.2 min, respectively. The median length of hospital stay for single and multi-track PNL was 6.6 (5.4, 8.7) vs. 10.2 (8.6, 12.3) days. Intra- and early postoperative infectious complications occurred in 101 (16.1%) and 54 (22.4%) patients, who underwent single and multi-track PNL, respectively. Bleeding occurred in 88 (13.9%) and 50 (20.8%) patients, respectively. After single and multi-track PNL, 54 (8.6%) and 21 (8.8%) patients needed a blood transfusion, respectively. CONCLUSION: Multi-track PNL is highly effective as a treatment modality for patients with complex forms of nephrolithiasis. Using the mini-tool significantly reduces the risk of bleeding when performing the additional access.

Selection of Progesterone Derivatives Specific to Membrane Progesterone Receptors.

The search of selective agonists and antagonists of membrane progesterone receptors (mPRs) is a starting point for the study of progesterone signal transduction mechanisms mediated by mPRs, distinct from nuclear receptors. According to preliminary data, the ligand affinity for mPRs differs significantly from that for classical nuclear progesterone receptors (nPRs), which might indicate structural differences in the ligand-binding pocket of these proteins. In the present work, we analyzed the affinity of several progesterone derivatives for mPRs of human pancreatic adenocarcinoma BxPC3 cell line that is characterized by a high level of mPR mRNA expression and by the absence of expression of nPR mRNA. The values were compared with the affinity of these compounds for nPRs. All tested compounds showed almost no affinity for nPRs, whereas their selectivity towards mPRs was different. Derivatives with an additional 19-hydroxyl group and removed 3-keto group had the highest selectivity for mPRs. These results suggest these compounds as the most selective progesterone analogs for studying the mechanisms of progestin action via mPRs.

3-O-methoxyimino group inhibits interactions between progestins and blood transcortin.

The interactions between E- and Z-isomers of 3-O-methoxyimino-pregn-4-ene-20-one and its 17α-hydroxy derivative and transcortin from human blood were investigated. The substitution of the progesterone 3-oxo group for a 3-O-methoxyimino group was shown to diminish the affinity of the steroid for transcortin by approximately one order of magnitude irrespective of the substituent's orientation. The data suggests that progesterone derivatives substituted thereby must have higher bioavailability compared to progesterone and must not significantly affect the biodynamics of glucocorticoid in vivo.

[Study of shearing strength between layers of light curing composite Esterfill PHOTO].

There was determined shearing strength of monolit samples of light curing material and samples received by modeling of further layers on surfaces with and without inhibited layer and also tensile strength of layers connected with the help of light curing adhesive. The study was performed on enamel, dentine and cutting edge masses from set of light curing material Esterfill PHOTO for prosthetic purposes. The received results showed that shearing strength between layers of enamel, dentine and cutting edge masses of Esterfill PHOTO varied between 22 and 28 MPa and tensile force divided by the nominal surface area did not depend upon the way of sample modeling. Distraction zone represented half of the cone turn out of substrate. More rigid material chopped in the process of distraction lesser volume off substrate. For prosthetic purposes it was recommended to use the equipment allowing to combine the final photopolymerization of the article with annealing under high temperature conditions or make annealing of the ready article after photopolymerization.

[An enamel adhesion study of Esterfill adhesives with chemical and light hardening]. / Izuchenie adgezii k émali adgezivov "Esterfill" khimicheskogo i svetovogo otverzhdeniia.

The purpose of this work is to define the dependence of adhesive bond strength on a way of cure of adhesive system, application of the primer and bond in two step or in one step in vitro. Chemically curing "Esterfill bond" (AB) and both light-curing primer and bond, and composite hybrid light-curing restorative material "Esterfill PHOTO" (EP) (DIAS LTD, Russia) were used. The shear bond strength was measured according to recommendation of ISO 11405:1994. The apparatus for these tests corresponds to ISO 10477, addition I. Shear bond strength was measured on enamel of 83 extracted human molars. Teeth were divided into 7 groups. Before using of adhesive system enamel was etched by 37% phosphoric acid during 60 sec. For measuring of shear bond strength the post composite restorative material "EP" (dentin) has been used. The received data show that the shear bond strength does nat depend on the type of cure, the composition of the bonds being similar. Using primer before application of the bond increases the shear bond strength approximately by 4-5 MPa. The inclusion of the primer in the content of the bond system increases the adhesion to enamel by 9 MPa.

[The clinical evaluation of the quality of tooth filling after exposure to hydroxyethylidene diphosphonic acid]. / Klinicheskaia otsenka kachestva plombirovaniia zubov posle vozdeistviia oksiétilidendifosfonovoi kisloty.

Ultrastructure of dental enamel was examined under electron microscope after exposure to hydroxyethylene diphosphonic (HEDP) acid and prophilometry of enamel surface was carried out after its exposure to acid salts; clinical studies in 105 patients aged 18-50 years with different diseases of hard dental tissues were carried out in order to assess the duration of filling preservation after dental enamel treatment with HEDP salts. Clinical results were assessed from subjective sensations of patients and data of examination. The criteria of assessing the results were presence of a filling in a filled carious cavity, marginal adhesion of the filling, alteration of color along the external interface of the filling, caries relapses, status of dental pulp and periapical tissues. Clinical and laboratory studies showed that treatment with HEDP acid creates favorable conditions for tooth filling.