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Introduction. Currently, the most common method of treating extended urethral strictures is augmentation urethroplasty using oral mucosa grafts. Analysis of the long-term outcomes of this surgery type shows a high incidence of relapses and complications.Purpose of the study. To improve the outcomes of augmentation urethroplasty, in particular the dorsal inlay (Asopa) technique, in patients with extended spongy urethral strictures by minimizing the risk of recurrent strictures.Materials and methods. The study is based on an analysis of the surgery in 90 patients (aged 18-72 years) with extended spongy urethral strictures. Seventy patients (group I) underwent dorsal inlay augmentation urethroplasty according to the Asopa technique, and 20 patients (group II) — according to the author's modified technique. Statistical data analysis was carried out using the SPSS ver.26 software (SPSS Inc. Chicago, IL, USA).Results. A comparative analysis of the course of the early postoperative period showed a lower number of complications in group II patients compared to group I — 20.0% versus 34.3%, respectively. The recurrent strictures were registered for groups I and II in 18.8% and 5.6% of cases 6 months after surgery, respectively. The recurrent urethral narrowing was most often localized in the area of distal anastomosis between the buccal graft and the native urethra in patients from both groups.Conclusion. The modified dorsal inlay augmentation urethroplasty technique developed and implemented in clinical practice by increasing the internal urethral lumen in the areas of proximal and distal anastomosis between the buccal graft and the native spongy urethral body allows minimizing the risks of recurrent urethral narrowing after augmentation urethroplasty.

Introduction. Augmentation urethroplasty using buccal mucosa is currently the optimal method for treating extended urethral strictures. However, this surgery is associated with a fairly high frequency of relapses and complications. One of the reasons that can determine the success or negative outcome of surgery is the morphological structure of the graft, which requires more in-depth research.Purpose of the study. To evaluate the initial morphological state of the buccal mucosa in men and determine the feasibility of its pharmacotherapeutic preparation as a predictor of improving the quality of autograft engraftment in augmentation urethroplasty.Materials and methods. The morphological structure of buccal mucosa fragments was studied in 20 patients with extended strictures of the spongy urethra. The objects of morphological research were intact oral mucosa before augmentation urethroplasty (1 biopsy) and mucosal fragments after 7 days of oral treatment with «Listerine» antiseptic solution (2 biopsies). The biopsy material was examined microscopically using standard staining (hematoxylin-eosin) and immunohistochemical methods.Results. The initial histological structure of the buccal mucosa in every third patient was accompanied by inflammatory infiltration at the level of the subepithelial layer with desquamation of the epithelium. a pronounced increase and strengthening of intercellular contacts in grafts proved histologically and immunohistochemically, which was characterized by pronounced expression of antibodies throughout the thickness of the epithelial layer, after week-long handling of the oral cavity with an antiseptic. At the same time, there is a «self-organization» of the submucosal base by reducing oedema, strengthening intercellular and focal adhesion contacts, with an increase in the components of the vascular bed and the number of vascular «plumules».Conclusion. Thus, a week-long preoperative treatment of the oral cavity allows stopping damage to the epithelium and inflammatory infiltration in the submucosal base with an improvement in its vascularization, which can be regarded as a positive factor for subsequent graft implantation.

Objectives To carry out calculations involved in the design of a microwave mixer with a diplexer with the formation of the antiphase heterodyne signal using a slot resonator.Method In order to calculate and optimise the characteristics, design and topological parameters of microwave mixers, the results of the design bandpass filter PF and low-pass filter (LPF) mixers of through-feed type were used. The characteristics of mixers and their structural elements were calculated using the Serenade software package intended for the automated calculation of microwave devices. A distinct feature of designing mixers (with a diplexer) involves the need to optimise the topology of the diplexer before optimising the mixer characteristics.Results The characteristics of nonlinear distortions show that the maximum power level at the mixer inlet should not exceed -15 – -20 dBm. In order to attenuate the intermodulation distortions of the 3rd order, this level should be higher that 50 dBs. The relatively low level of compression and suppression of harmonic and intermodulation distortions associated with the minimisation of the heterodyne power level at the calculation of characteristics of mixers of the required heterodyne power level (Rh ~ 5-7 dBm) is due to the minimum expenses at the realisation of sources of heterodyne signals. A noticeable improvement in the characteristics of mixers by nonlinear distortions can be achieved by shifting the operating point at the points on the current-voltage characteristic (VAC) diodes by an external voltage source with a simultaneous increase in Ph by several dB (up to Ph = 10 dBm).Conclusion A mode of increased nonlinear distortion suppression can be practically realised by switching on diodes through resistive-capacitive circuits (auto-shift) or using diodes with an increased potential barrier. The calculation shows that it is possible to realise sufficiently small conversion losses of 6.6-8.0 dB at low levels of Rh ~ 5-7 dBm.