[SEROTONERGIC REGULATION OF THE DUODENUM CONTRACTIONS].

The review contains an analysis of literature data on enhancement mechanisms of duodenum contractions arising during stimulation of the sympathetic trunk in the right thoracic cavity in dogs. It is established in experiments that There are mostly enhancement, not relaxation of the organ contraction occured. In this case the stimulatory effect due to the excitation of the parasympathetic fibers is excluded. The trimeperedin inhibit the serotonin receptors of autonomic ganglia neurons stimulatory activity during the nerve stimulation. It is concluded that the sympathetic trunk contain the preganglionic serotonergic nerve fibers, whose activation leads to increased bowel contractions. Direct adipinate-serotonin administration increased the bowel contraction that confirm the preganglionic serotonergic nerve fibers presence in the sympathetic trunk. The practical significance of these studies is that the new approach to the development of pharmacological agents to stimulate the motility of the gastrointestinal tract was found. The trimeperedin may inhibit the serotoninergic nerves activity that resulted in the perioperative constipation in surgical patients. Practical recommendation to exclude trimeperedin in preparing the patient for surgery to prevent perioperative constipation is formulated.

Mechanism of strain-influenced quantum well thickness reduction in GaN/AlN short-period superlattices.

We report on the mechanism of strain-influenced quantum well (QW) thickness reduction in GaN/AlN short-period superlattices grown by plasma-assisted molecular beam epitaxy. Density functional theory was used to support the idea of a thermally activated exchange mechanism between Al adatoms and Ga surface atoms that is influenced by the strain state of the GaN QWs. These ab initio calculations support our experimentally observed reduction in QW thickness for different intrinsic strains.

[The significance of different 5-HT-receptors in regulation of gastrointestinal motility].

Serotonergic mechanisms are involved in many, if not all digestive functions of the gastrointestinal tract. A special role is played by serotoninergic structures in the neuronal control of motor activity. The study of these structures is of particular interest due to the widespread occurrence of irritable bowel syndrome, covering up to 20% of the adult population, which makes the research in this area up to date and in demand. Acute experiments were performed on 102 Wistar rats in 6 series. Experiments were carried out under general anesthesia (Nembutal, 60 mg/kg) and mechanical lung ventilation. Motor responses of the stomach, duodenum and ascending colon were studied to i.a. Serotonin adipate infusion (1 mg/kg) during joint blockade of sympathetic and parasympathetic chains of ANS, as well as on the background of the blockade of various 5-HT-receptors. Infusions of 5-HT-blockers reduce the magnitude of motor responses in stomach, duodenum and colon in varying degrees. Based on these data found 5-HT(1b)-receptors are mainly located in enteric neurons. The distribution of 5-HT(2b-4)-receptor is heterogeneous: 5-HT(2b)-receptors are located in enteric neurons of the stomach and intestinal myocytes; 5-HT3-receptors localized in the ganglia supplying the stomach and colon and 5-HT4-receptors are mainly located in the smooth muscle of the stomach, duodenal and ascendent colon enteric neurons.

[Lower gastrointestinal dysfunction in patients with Parkinson's disease]. / Disfunktsiya nizhnikh otdelov zheludochno-kishechnogo trakta u patsientov s bolezn'yu Parkinsona.

OBJECTIVE: To assess the lower gastrointestinal tract dysfunction in patients with Parkinson's disease (PD) and to reveal its relationships with motor and non-motor symptoms. MATERIAL AND METHODS: One hundred and eighteen patients with PD of I-III Hoehn and Yahr (H&Y) stages were studied using UPDRSI-IV, Sch&En, PDQ-39, MMSE, BDI, STAI-S and STAI-T, PFS-16, NMSQ, GSRS, BSFS, AUA. Body mass index and saliva amount and lacrimation (Schirmer's test) were assessed. RESULTS: Constipation from mild to moderate intensity was present in 71.2% of the patients; predominantly mild diarrhea occurred in 27.9%; alternations of diarrhea with the difficulty in intestine emptying were observed in 25.4%. We found significant correlations of constipation with the following parameters: Sch&En scales (rS=-0.291) and PDQ-39 (rS=0.478), patient's age (rS=0.275), H&Y stage (rS=0.2604), UPDRS (rS=0.254), axial motor symptoms of parkinsonism, and a number of affective and autonomic disorders, most of which were partly dopamine-resistant. Diarrhea did not affect the quality of patient's life, or depend on age, PD stage, main digital and non-motor symptoms, but directly correlated with the severity of constipation (rS=0.263) and other gastrointestinal disorders. There were no effects of dopaminergic therapy, including levodopa, dopamine-receptor-agonists, and amantadine, on the lower gastrointestinal tract dysfunction. CONCLUSION: Dysfunction of the lower gastrointestinal tract (predominantly from mild to moderate intensity) was detected in most PD patients of I-III stages. Our data indicate a complex pathogenesis of the PD impaired bowel emptying, involving degeneration of non-dopaminergic structures, and the predominant influence of concomitant diseases and inadequate laxative therapy on the formation of diarrhea syndrome in PD.

Study of the nature of sympathetic trunk nerve fibers enhancing gastric motility.

Stimulation of the sympathetic nerve in the thoracic cavity often does not inhibit, but increases stomach contractions in dogs. Blockade of α- and ß-adrenoceptors potentiates this stimulatory effect, while blockade of S(1,2)-receptors localized mainly in smooth muscle cells eliminates it. It is concluded that sympathetic nerve includes serotonergic fibers stimulating gastric motility.

Impact of defects on photoexcited carrier relaxation dynamics in GeSn thin films.

We report the results of a study that was conducted to investigate the recombination paths of photoexcited charge carriers in GeSn thin films. The charge carrier lifetime was predicted as a function of temperature from a description of photoconductivity transients, assuming co-influence of Shockley-Read-Hall and radiative carrier recombination paths. We identify that dislocations are the source of a band of electronic states with the highest occupied state at E V + (85÷90) meV that acts as Shockley-Read-Hall centers determining the charge carrier lifetime. The photoluminescence (PL) and photoconductivity spectroscopy have been applied to distinguish between the contribution of both band-to-band and dislocation-related electron transitions. The PL band was found to demonstrate a low-energy shift of about 80 ± 20 meV relative to the edge of the photoconductivity spectra in the indirect bandgap GeSn films with dislocations. The role of a different nature deeper acceptor level at E V + (140 ÷ 160) meV in the recombination processes of the GeSn layers with better structural quality and the Sn content higher than 4% was discussed. This detailed understanding of the recombination processes is of critical importance for developing GeSn/Ge-based optoelectronic devices.