Nikita Alekseevich Adamenkov

Purpose . To improve the accuracy of diagnosing microcirculation disorders in the intestinal wall tissues in small laboratory animals by introducing hyperspectral imaging in combination with a controlled polychrome LED light source. Materials and methods. 10 clinically healthy Wistar rats were used in the study. Intestinal ischemia was modeled by the ligation of mesenteric vessels after laparotomy under inhalation anesthesia. Relaparotomy was performed in 1, 6 and 12 hours. The viability of intestinal tissues and the identifi cation of secondary pathological changes were assessed with the visual Kerte method and a polychrome LED light source providing contrast visualization of biological tissues. Intestinal wall perfusion was assessed by the hyperspectral imaging system. Intestinal resection followed by the sampling for morphological examination was made according to time intervals established by the examination protocol. Results. Spectral composition of the light source, which reliably detects the intestinal wall necrosis, includes two spectral lines with maxima of λpeak = 503 nm and λpeak = 594 nm at 2:1 intensity ratio. Hyperspectral imaging allowed to get two-dimensional maps of tissue saturation with the following values: 66 ± 2 % (intact tissue), 42 ± 5 % (1 hour), 26 ± 3 % (6 hours) and 21 ± 3 % (12 hours). The performed morphological analysis revealed three key ischemic intervals: 1 hour (ischemia onset), 6 hours (reversible ischemia) and 12 hours (irreversible necrosis). The obtained data confi rm the signifi cant decrease in saturation which correlates with morphological changes, and the effectiveness of the discussed technique for assessing the viability of intestinal tissues. Conclusion . In the course of the study, the authors have developed a technology for optimizing the lighting during surgery so as to improve contrast imaging of ischemic and necrotic tissue changes. Hyperspectral imaging promotes non-invasive and objective intraoperative assessment of the ischemic damage in the intestinal wall without any exogenous fl uorescent drugs. The obtained results also demonstrate the prospects of introducing optimized lighting and hyperspectral imaging into clinical practice so as to improve diagnosis and surgical treatment of ischemic intestinal lesions.

An analysis of data from national and foreign literature was carried out in terms of intraoperative determination of the intestinal viability in cases of developing the diseases in the abdominal cavity organs, associated with impaired intestinal blood supply. The basis of this work is the analysis of the modern literature on the methods of intraoperative evaluation of mesenteric ischemia. Impaired mesenteric blood supply is often the consequence of a number of reasons of developing critical conditions (mesenteric thrombosis, acute adhesive intestinal obstruction, incarcerated hernia etc.), also representing a high risk factor for lethal outcomes. Special attention is paid to the occlusion-related pathogenetic mechanism of developing mesenteric ischemia, which is accompanied by rapid development of irreversible morphological changes in the tissues and by significant disorders in the homeostasis systems of the organism. The generally available method for visual evaluation of the intestine viability is not always valid in terms of determining the degree of intensity of the ischemic changes in the intestinal wall. The algorithm of determining the intestine viability includes the determination of the intestine color, the peristaltic motions, the pulsation and the blood filling of mesenteric vessels with dynamic evaluation of these signs after the injecting the local anesthetic drug solution into the mesenterium and after “warming” the intestine with towels soaked in warm sodium chloride solution. In the current surgical conditions, a more precise method is required for intraoperative determination of the tissue viability. For the purpose of the objective evaluation of the intestinal blood supply, the recommendations include using intraoperative ultrasonic and laser Doppler flowmetry, as well as the regional transillumination angiotensometry of the intramural vessels in the small intestine. At the same time, a number of optical spectroscopy and visualization methods show high sensitivity to changes in blood microcirculation without using exogenous contrasting, which can also be successfully used when evaluating the intestinal circulation. According to data from modern literature, there is still controversy on the efficiency of various methods for intraoperative evaluation of disorders of the regional blood microcirculation and the intestine viability, which justifies the conduct of further research works.

Background. Acute intestinal ischemia is a disease characterized by a violation of blood supply, which leads to hypoxia of intestinal wall tissues and secondary pathological changes. One of the main factors determining the urgency of the problem of acute intestinal ischemia is the intraoperative determination of the viability of the intestinal wall, which plays a leading role in determining the volume of surgery and in the prognosis of the postoperative period. Objective. Improving the results of diagnosing disorders of the blood supply to the tissues of the intestinal wall in small model animals based on the use of the hyperspectral imaging method. Material and methods. The experimental study was conducted in 9 clinically healthy, sexually mature Wistar laboratory rats. The assessment of intestinal viability and the development of secondary pathologic changes was performed using the Kerte’s visual method. Intestinal wall perfusion was determined using a hyperspectral imaging system. The object of the study was a model of intestinal ischemia with violation of mesenteric blood flow with the formation of a ligature blocking the feeding vessel during laparotomy under inhalation anesthesia. Relaparotomy was performed after 1, 6 and 12 hours, during which the intestine was removed from the abdominal cavity and an intraoperative assessment of intestinal tissues viability was performed. Intestinal resection with sampling of fragments for morphologic examination was performed in accordance with the time intervals of ligature application of the study protocol. Results. The studies resulted in obtaining two-dimensional color maps of intestinal tissue saturation at different stages of ischemia modeling (1, 6 and 12 hours). The mean saturation value for the intact intestinal wall was 66±2%, after 1 hour from the time of ischemia modeling it was 42±5%, after 6 hours — 26±3%, after 12 hours the mean saturation value was 21±3%. Conclusion. Application of hyperspectral imaging allows noninvasive and objective intraoperative assessment of the nature of ischemic damage of the intestinal wall without additional use of exogenous fluorescent substances. This may improve the quality of surgical procedures for ischemic intestinal lesions.

BACKGROUND: Despite an enormous progress in the field of reproductive endocrinology, the mechanisms of premature ovarian insufficiency have not been fully understood so far. Knowledge of the supposed causes and mechanisms underlying the development of premature ovarian insufficiency has expanded significantly in recent years, mainly due to advances in genetics and the creation of models for experimental research. The experimental modeling of premature ovarian insufficiency, which is as close as possible to the origin and development of the corresponding disease in humans, is effectively used to elaborate promising therapeutic approaches, in particular, to test new drugs or biologically active agents in order to study their preventive or curative effects. This article discusses the main methods of the experimental modeling of POI in laboratory animals. We have herein summarized the literature data related to the development of the clinical and morphological picture of the disease, with the advantages and disadvantages of each of the models analyzed. AIM: The aim of this study was to modify the premature ovarian insufficiency modeling methodology to substantiate the effectiveness and to test new directions in drug therapy with subsequent implementation in clinical practice. MATERIALS AND METHODS: The new method is based on the creation of an experimental premature ovarian insufficiency model in female Wistar rats. To obtain this model, experimental rats were randomized into two groups: 1) animals receiving cyclophosphamide at a dose of 150 mg/kg b.w. subcutaneously once (n = 10); 2) animals receiving 2 ml of saline intraperitoneally once (n = 9). On day10, the animals were removed from the experiment. After autopsy, a visual assessment of morphological changes in the ovaries was carried out, and a right-sided ovariectomy was performed. RESULTS: When using the proposed model, the reproducibility rate of POI has reached 100%. CONCLUSIONS: Our modification of the method ensures the creation of a highly reproducible premature ovarian insufficiency model in Wistar rats. Another significant advantage of this modeling method is its ease of implementation and economic efficiency.

Introduction. Diseases accompanied by a violation of the blood supply to the intestinal wall occupy one of the main places in urgent surgery of the abdominal organs. Intraoperative assessment of intestinal viability is one of the most difficult tasks and plays a leading role in determining the volume of surgical aid, predicting the course of the postoperative period.Aim. To study the possibility of using contrast imaging using a controlled polychrome LED light source to assess the viability of the intestinal wall of a model animal in conditions of acute ischemia.Materials and methods. The work is based on the results of experimental studies conducted on 15 clinically healthy sexually mature laboratory rats. The simulation of acute small intestine ischemia lasting from 15 minutes to 12 hours was performed by ligation of the major vessels. Each animal underwent a relaparotomy after a corresponding time interval. The intestine was extracted from the abdominal cavity and visual parameters of wall necrosis were assessed using the Kerte method and using a polychrome LED light source for contrast imaging of biological tissues during surgery. After determining the visual signs of necrosis, intestinal fragments were submitted for pathomorphologic examination. The study was ended by removing the animal from the experiment according to the protocol approved by the Ethics Committee.Results. The spectral composition of the light source providing the most reliable detection of necrosis of the intestinal wall is represented by two spectral bands with maximum wavelengths of peak = 503 nm, peak = 594 nm and an approximate ratio of band intensities of 2:1. By morphological study, the following intervals were found to be significant when simulating small intestinal ischemia in the experiment: 1 hour after ligation - time of onset of ischemia, 6 hours - time when ischemia is reversible, and 12 hours - time when small intestine necrosis is recorded. Conclusions. The use of a controlled shadowless semiconductor light source for contrast imaging of biological tissues during surgery in the selected mode improves the definition of visual parameters of intestinal viability.

At the present stage of medicine, minimally invasive interventions are the methods of choice for the removal of concrements from the biliary tract. Treatment of choledocholithiasis in clinical situations when the implementation of endoscopic, laparoscopic, minilaparotomic and laparotomic surgical techniques is impossible or ineffective, is determined by the possibilities of antegrade x-ray surgical interventions. A clinical observation of successful treatment of a patient with mechanical jaundice syndrome caused by choledocholithiasis on the background of gallbladder cancer is presented. The use of antegrade choledochocholangioscopy with percutaneous pneumatic lithotripsy and lithoextraction allowed to successfully eliminate choledocholithiasis and achieve good treatment results.