PATHOMORPHOLOGY OF EXPERIMENTAL INFECTION CAUSED BY DORMANT YERSINIA PSEUDOTUBERCULOSIS STRAINS

In the 2000s, with the development of scientific research on the uncultivated (dormant) state of pathogenic bacteria, the ideas about persistent, chronically recurrent infections, difficult to respond to antibiotic therapy have begun to shape. However, regarding human pseudotuberculosis (Far Eastern scarlet-like fever, FESLF), this question remains open. While analyzing the pathology of pseudotuberculosis, its clinical and epidemic manifestation as FESLF, we identified the etiopathogenetic prerequisites for the disease recurrence and development of persistent infection [3]. In this study, it was found that the strains of Yersinia pseudotuberculosis, which were in a dormant state, caused the development of a peculiar granulomatous inflammation in target organs with pronounced delayed-type hypersensitivity reactions in vivo. To reproduce the experimental infection, sexually mature white mice were inoculated with the strain 512 Y. pseudotuberculosis, serotype I sored for 10 years at the Museum of the Research Somov Institute of Epidemiology and Microbiology and transformed into a dormant state. For comparative studies, a dormant form from vegetative bacteria of the strain 512 Y. pseudotuberculosis was obtained by exposure to a large dose of kanamycin (the minimum antibiotic dose was exceeded 25 times). The infecting dose of both forms of bacteria was 108 µ/mouse. Samples of target organs (lung, liver, spleen) were collected for histological examination on days 3, 7, 10, 14, 21 and 32 after infection. Histological sections with 3-5 µm thickness were stained with hematoxylin and eosin according to standard techniques. It was established that strains of Y. pseudotuberculosis in dormant state caused in vivo development of a peculiar granulomatous inflammation due to delayed-type hypersensitivity reactions (DHR), which characterizes the protective reaction in infected host and reflects formation of local, tissue immunity in target organs. The peculiarities of granulomatous inflammation were revealed, in comparison with that of found during infection with vegetative ("wild") Y. pseudotuberculosis bacteria, namely: the granulomas were predominantly small in size, clearly delimited from the surrounding tissue, without destruction of central zone cells and formation of the so-called "granulomas with central karyorrhexis" (terminology proposed by A.P. Avtsyn) [4]; perivascular infiltrates and vasculitis consisted mainly of lymphocytes and often had a follicle-like appearance, resembling the follicles in lymphoid organs; in the lungs, a well-marked reaction of the bronchial-associated lymphoid tissue was observed, and in the spleen, a follicular hyperplasia, indicating a T-cell defense reaction, was observed. Thus, the causative agent of Y.pseudotuberculosis infection / FESLF, being in a dormant state, initiates the development of immunomorphological changes of a protective nature such as productive granulomatous inflammation with reactions of local tissue immunity in target organs and can contribute to the formation of persistent infection.

Soft-tissue coverage for wound complications following total elbow arthroplasty

Background: In patients with total elbow arthroplasty (TEA), the soft-tissue around the elbow can be vulnerable to soft-tissue complications. This study aims to assess the outcomes after soft-tissue reconstruction following TEA. Methods: We retrospectively included nine adult patients who underwent soft-tissue reconstruction following TEA. Demographic data and disease characteristics were collected through medical chart reviews. Additionally, we contacted all four patients that were alive at the time of the study by phone to assess any current elbow complications. Local tissue rearrangement was used for soft-tissue reconstruction in six patients, and a pedicle flap was used in three patients. The median follow-up period was 1.3 years (range, 6 months–14.7 years).Results: Seven patients (78%) underwent reoperation. Four patients (44%) had a reoperation for soft-tissue complications, including dehiscence or nonhealing of infected wounds. Five patients (56%) had a reoperation for implant-related complications, including three infections and two peri-prosthetic fractures. At the final follow-ups, six patients (67%) achieved successful wound healing and two patients had continued wound healing issues, while two patients had an antibiotic spacer in situ and one patient underwent an above-the-elbow amputation. Conclusions: This study reports a complication rate of 78% for soft-tissue reconstructions after TEA. Successful soft-tissue healing was achieved in 67% of patients, but at the cost of multiple surgeries. Early definitive soft-tissue reconstruction could prove to be preferable to minor interventions such as irrigation, debridement, and local tissue advancement, or smaller soft-tissue reconstructions using local tissue rearrangement or a pedicled flap at a later stage.

P044 ATRAUMATIC AND CONSISTENT HERNIA MESH FIXATION: PERFORMANCE AND SAFETY IN A LAPAROSCOPIC IPOM PORCINE MODEL

Aim Demonstrate the performance and safety of TISSIUM on-demand activated adhesive for atraumatic hernia mesh fixation in a laparoscopic IPOM porcine model. Material and Methods Full thickness 4 cm in diameter excisional abdominal defects (n = 14) were created in pig (n = 8). The defects were repaired through laparoscopic intraperitoneal mesh placement using commercial composite meshes fixed with TISSIUM adhesive (n = 8) or resorbable tacks (n = 6). The animals were sacrificed after 28 and 90 days. An independent pathologist evaluated abdominal adhesion, mesh shrinkage, local tissue tolerance and tissue ingrowth through histological analysis (H&E and Movat Pentacrome) at sacrifice. Fixation strength of the explanted abdominal walls was also assessed via burst-ball. Results No adverse events were observed at implantation or during the survival period. All the meshes were in place at sacrifice. Mesh shrinkage and abdominal adhesion scores were similar between the two groups. Histological analysis of the mesh demonstrated equivalent quality of tissue ingrowth and excellent local tissue tolerance with minimal/mild foreign body response and mononuclear cells inflammation. The repair strength, evaluated through a burst ball method 90 days after implantation, showed no significant difference between the TISSIUM adhesive and tacks. Usability is currently being evaluated in clinically relevant models. Conclusions In this preclinical study the TISSIUM adhesive demonstrated similar fixation strength and quality of repair when compared to commercial tacks. This technology has the potential to impact hernia procedures standardization and reduce pain often associated with current fixation technologies.

P046 ATRAUMATIC AND CONSISTENT HERNIA MESH FIXATION: PERFORMANCE AND SAFETY IN A LAPAROSCOPIC IPOM PORCINE MODEL

Aim Demonstrate the performance and safety of TISSIUM on-demand activated adhesive for atraumatic hernia mesh fixation in a laparoscopic IPOM porcine model. Material and Methods Full thickness 4 cm in diameter excisional abdominal defects (n = 14) were created in pig (n = 8). The defects were repaired through laparoscopic intraperitoneal mesh placement using commercial composite meshes fixed with TISSIUM adhesive (n = 8) or resorbable tacks (n = 6). The animals were sacrificed after 28 and 90 days. An independent pathologist evaluated abdominal adhesion, mesh shrinkage, local tissue tolerance and tissue ingrowth through histological analysis (H&E and Movat Pentacrome) at sacrifice. Fixation strength of the explanted abdominal walls was also assessed via burst-ball. Results No adverse events were observed at implantation or during the survival period. All the meshes were in place at sacrifice. Mesh shrinkage and abdominal adhesion scores were similar between the two groups. Histological analysis of the mesh demonstrated equivalent quality of tissue ingrowth and excellent local tissue tolerance with minimal/mild foreign body response and mononuclear cells inflammation. The repair strength, evaluated through a burst ball method 90 days after implantation, showed no significant difference between the TISSIUM adhesive and tacks. Usability is currently being evaluated in clinically relevant models. Conclusions In this preclinical study the TISSIUM adhesive demonstrated similar fixation strength and quality of repair when compared to commercial tacks. This technology has the potential to impact hernia procedures standardization and reduce pain often associated with current fixation technologies.

HIFU Varicose Vein Treatment Using Veinsound Device Feasibility Study On Sheep

The purpose of this nonclinical study was to evaluate the performance (in terms of vein occlusion) and the local tissue effects of echo-guided HIFU (High Intensity Focused Ultrasound) treatments in sheep’s saphenous veins.HIFU treatments were used to treat 4 saphenous veins. Two HIFU doses were evaluated 4s/60J and 7s/105J with and without tumescence injection in perivenous tissues. Before and after treatment, ultrasound scans were performed (at Day 0, 3, 7 and 21). Sheep were then euthanized at D21. Local tissue effects were evaluated based on the macroscopic observations, while the evaluation of the device performance was based on ultrasonic scan.Macroscopically throughout the study duration, for dose of 4s/60J and with tumescence, significant lumens diameter reduction of 84% was observed without skin burns. For doses of 4s/60J without tumescence and 7s/105J skin burns of slight to severe grade was observed along the vein, while no thrombus nor lumen reduction were observed.