[Transanal endoscopic rectal resection: immediate and long-term results]. / Transanal'naya endoskopicheskaya rezektsiya pryamoi kishki: neposredstvennye i otdalennye rezul'taty.

OBJECTIVE: To analyze the results of transanal endoscopic microsurgery in patients with rectal tumors. MATERIAL AND METHODS: We analyzed 87 transanal endoscopic resections of rectal benign tumors (35 patients) and rectal cancer cT1N0M0 (52 patients) for the period since 2012. RESULTS: There were 2 (3.8%) intraoperative intestinal wall perforations into abdominal cavity and 2 (3.8%) postoperative bleedings among patients with rectal cancer. Four (7.7%) patients developed recurrent rectal cancer (pT1N0M0 - 1 patient, pT2N0M0 - 3 patients; by tumor grades: G1 - 2 patients, G2 - 2 patients) within 1.6-5.2 years. All recurrent tumors were located on anterior rectal wall. In patients with rectal cancer, cumulative relapse-free survival was 0.923 (standard error 0.037), cumulative overall survival - 0.926 (standard error 0.043). There was 1 (4.3%) intraoperative intestinal wall perforation among patients with benign rectal tumors. Postoperative anastomotic leakage occurred in 1 (4.3%) patient. Recurrent benign tumors occurred in 2 (8.7%) patients with villous rectal tumors. No relapses were observed in patients with rectal adenomas (p=1.0). CONCLUSION: Transanal endoscopic rectal resection is effective for benign rectal tumors and rectal cancer pT1N0M0 with high relapse-free and overall survival and low complication rate. Risk factors of recurrence are tumor stage pT2N0M0, tumor location on anterior wall and distance from the anus over 10 cm.

[The outcomes of different pancreatodigestive anastomoses in pancreatoduodenectomy].

AIM: To compare early results after pancreaticoduodenectomy depending on variant of pancreatico-digestive anastomosis. MATERIAL AND METHODS: It was analyzed early results of 207 pancreaticoduodenectomies for cancer which were performed for the period 2010-2014. Pancreatointestinal and pancreatogastric anastomoses were applied in 165 and 42 patients respectively. RESULTS: Complications were observed in 73 (44.2%) and 18 (38.3%) patients after pancreatointestinal and pancreatogastric anastomoses respectively. Six patients died after pancreatointestinal anastomosis. At the same time there were no deaths in the group of pancreatogastric anastomosis. Differences were significant. Postoperative hospital-stay was similar in both groups.

[Analyzing the fine-scale dynamics of two dominant species in a Polytrichum­Myrtillus pine forest. I. A homogeneous Markov chain and cyclicity indices].

Using long-term direct observations in a Polytrichum-Myrtillus pine forest, we have constructed and verified a homogeneous Markov chain model for two dominant species (Vaccinium myrtillus and V. vitis-idaed) at the late stages of succession. The sampling design features a large sample size (2000 quadrats) on permanent transects, several re-examinations with the interval of 5 years, and the use of species rooted frequency. As a model of the process under concern, the discrete Markov chain accounts for the following four states: both species being absent on the quadrat, one of them being present alone, and the joint presence of the both; the model time step coincides with the time interval between observations. The model is calibrated on the data of two successive examinations and verified on that of one more examination. All possible transitions between the states are revealed to realize in quadrats for one time interval, as well as the absence of transitions at each state, which results in the complete digraph (directed graph) of transitions. Major model results are obtained by the formulae of finite Markov chain theory: the steady-state square distribution, cyclicity characteristics, and the mean durations of stages in the fine-scale dynamics. As a steady-state (stable) outcome of succession, the distribution among quadrats is expected where 30% of quadrats are occupied by V. myrtillus alone, 11% by V. vitis-idaea alone, both species are present on 18% of quadrats, and 41% of quadrats are 'empty'. This demonstrates a possibility for V. myrtillus and V. vitis-idaea to coexist stably at the latest stages of succession, with the clear predominance of V. myrtillus, yet without competitive exclusion. The quantitative characteristics of cyclicity and the durations of stages in the fine-scale dynamics enable us to estimate the total duration of secondary post-fire succession as about 45 years (to reach a distribution of states that differs less than 5% from the steady-state one). Out of the four states specified, the quadrats with V. vitis-idaea alone persist for the least time (8 years) on the average, while 'empty' ones persist for the greatest time (18 years). Forecasting the dynamics for one model time step forward and comparing the forecast with the real square distribution have revealed the measure of difference to be 5.4%. This illustrates the efficiency of the (time-)homogeneous Markov chain as a short-term forecast tool, yet leaves open the question whether the homogeneity hypothesis be true in the longer term.

Experimental study of cognitive aspects of ambivalent foraging as exemplified by the great tit.

A hypothesis of ambivalent foraging is proposed based on ideas about dual treating of the prey by a consumer: the food value attracts while the danger repulses. The foraging strategy of the great tit was investigated experimentally with the use of artificial "food patches" with variable amounts of dangerous prey (live red wood ants) and non-dangerous prey (fly larvae). With non-dangerous prey, the behavior of the birds corresponded to the known marginal value theorem: they proceeded with foraging until the resources were exhausted. We found the threshold amount of dangerous prey that prevents tits from hunting.

[Importance of urgent histological investigation in surgical treatment of biliopancreatoduodenal zone carcinoma]. / Znachenie srochnogo gistologicheskogo issledovaniia v khirurgicheskom lechenii raka biliopankreatoduodenal'noi zony.

Urgent intraoperative investigation allows a surgeon, depending on the morphological conclusion, to conduct individual surgical intervention in the form of anastomosis with penetration into the tissue of the pancreas. The method decreases the rate of surgical complications, improves immediate results of patient treatment and reduces postoperative lethality. This proves the importance of morphology in the surgical treatment of tumours in the zone concerned.