The Vagal Control of the Ileo-Cecal Sphincter in the Cat

In acute experiments on chloralosed cats the effect of efferent cervical vagal stimulation on a flow through the ileo-cecal sphincter (ICS) was studied. The motor activity of the jejunum, ileum and large intestine adjacent to the sphincter was recorded simultaneously. Vagal stimulation caused a decrease in the transsphincteric flow and increased motor activity in the ileum. Increased motor activity in the proximal colon was recorded only occasionally. When the vagal nerves were stimulated during continuous splanchnic stimulation the transsphincteric flow was decreased although the tone and motility of the ileum was supposed. Furthermore, guanethidine (1–3 mg/kg b.w.) blocked or suppressed the effect of vagal stimulation on the transsphincteric flow while the excitatory response of the proximal colon was greatly enhanced. This indicates that the reduction of the transsphincteric flow following vagal stimulation was at least partly due to a direct effect of the vagal nerves on the sphincteric muscle and not to a squeezing effect of that part of the colonic wall that surrounds the sphincter. Atropine (0.1 and 1 mg/kg b.w.) blocked all responses to vagal stimulation. Thus, both guanethidine and atropine blocked the vagally induced contraction of the ICS. Relaxation of the ICS was never obtained by vagal stimulation even when the tone of the sphincter had been increased by infusion of noradrenaline.     

Reflexogenic contraction of the ileo-cecal sphincter in the cat following small or large intestinal distension.

The effect of distension of a small or large intestinal loop on the ileo-cecal sphincter (ICS) in the cat was studied with a flow-recording technique. Distension of a small or large intestinal loop, isolated from the adjacent intestine, but with its mesenteric vascular and nervous supply intact, elicited a contraction of the ICS concomitant with an inhibition of the adjacent large and small intestinal motility. Vagal and pelvic nerve section did not affect the response to distension of the ICS nor exclusion of the adrenal glands from the circulation. The sphincter reflex could be entirely or almost entirely eliminated by cutting both the splanchnic and lumbar colonic nerves, but not one or the other. Spinal anesthesia bocked the reflex response indicating a spinal reflex arc. The reflex persisted after atropine and propranolol, while both guanethidine and phenoxybenzamine completely abolished the reflex contraction of the sphincter. The present results indicate that the excitatory intestino-ileo-cecal sphincteric reflex is a spinal reflex with the main afferent and/or efferent fibres located within the major splanchnic and lumbar colonic nerves. The excitatory motor response in the sphincter is adrenergic and mediated via alpha-receptors.     

Mucosal Lesions in the Small Intestine of the Cat during Low Flow

The mucosal changes, produced at the villous tips of the cat small intestine during a mimicked shock situation (regional hypotension at 30 mm Hg during nervous vasoconstrictor fibre activation), were examined macro-and microscopically. Macroscopically, petechial bleedings and ulcerations were regularly seen in the mucosa after a 2 h hypotensive period. The microscopic findings were characterized by epithelial lifting of various degrees at the tips of the villi and in some cases by a complete denudation of the villous tips. Intraluminal perfusion of a segment with oxygenated saline during the hypotension prevented or greatly reduced the mucosal lesions compared to control segments. On the other hand, intraluminal perfusion with nitrogenated saline did not change the mucosal lesions as compared with control. This strongly indicates that hypoxia per se plays an important role in the pathogenesis of the mucosal lesions, while the intestinal content (e.g. energy substrates or enzymes) does not appear to be of any great importance. It is suggested that the hypoxia is caused by an extravascular shunting of oxygen in the intestinal countercurrent exchanger.     

Morphology of the Upper Esophageal Sphincter or Cricopharyngeus Muscle Revisited

Histological examination of specimens from 22 donated elderly cadavers and 15 human fetuses revealed that the cricopharyngeus muscle (CPM) provided (1) posterior circular muscle fibers adjacent to the external aspect of the uppermost esophageal circular muscle and (2) a thin anterior sling connecting to that same muscle. Another thick lateral bundle of longitudinal muscle originated independently from a fascia covering the posterior cricoarytenoideus muscle, extended laterally and posteriorly, and occupied a space after the CPM had disappeared at the anterolateral angle of the esophagus below the cricoid. The thick fascia contained abundant elastic fibers along the internal surface of the pharyngeal constrictors (posteromedial elastic lamina), but was interrupted or discontinued near the cricoid origin of the CPM. As no submucosal smooth muscles or elastic fibers were connected to it, the CPM did not accompany a specific elastic structure at the interface between the pharyngeal and esophageal muscles. In fetuses, the medial half of the CPM was inserted into the cricoid while the lateral half continued to the sternothyroideus muscle or ended at a fascia covering the cricothyroideus. These anterolateral ends provided a mechanical load for longitudinal growth of the pharyngeal constrictors. Consequently, the CPM was unlikely to develop and grow to form the upper esophageal sphincter, and the muscle bundle crossing the lateral aspect of the pharyngo-esophageal junction appeared to have a secondary passive role as a sphincter. This situation contrasts with that of another sphincter in the human body formed from striated muscle. Clin. Anat., 33:782–794, 2020. © 2019 Wiley Periodicals, Inc.     

Mucosal Hemodynamics in the Small Intestine of the Cat during Reduced Perfusion Pressure

This study was performed with an indicator-dilution technique that allowed quantitative and separate investigation on the cat small intestine, of the “mucosal” as well as of the “villous” intravascular flows and volumes. When reducing arterial inflow pressure from about 100 to about 30 mm Hg “villous” plasma volume and mean transit time increased while “villous” plasma flow remained largely unaltered. Concomitantly, total intestinal blood flow decreased significantly indicating that a larger fraction of total plasma flow was diverted to the villi at low inflow pressure. When intestinal blood flow was reduced by increasing venous outflow pressure villous hemodynamics was largely unaffected. “Mucosal” red cell and plasma flows were affected in the direction of and, generally speaking, in proportion to total intestinal blood flow. These results suggest that the autoregulatory capacity of the villous vessels is larger than that of the vessels in the deeper parts of the mucosa.     

小肠黏膜下层细胞相容性的研究

评价猪小肠黏膜下层与人胚骨膜成骨细胞 (Human embryonic periosteal osteoblasts,HEPOB)、人胚皮肤成纤维细胞 (Hum an em bryonic skin fibroblasts,HESFB)及兔肾血管内皮细胞 (Rabbitrenal vascular endothelialcells,RRVEC)的细胞相容性。制备猪小肠黏膜下层 (Sm all intestinal submucosa,SIS) ,将 HEPOB、HESFB和RRVEC与小肠黏膜下层体外复合培养 ,采用相差显微镜观察细胞的黏附和生长 ,并用 MTT法测定细胞增殖 ,用流式细胞仪检测复合培养细胞在不同培养时间的细胞周期、细胞凋亡。结果表明三种细胞均可在 SIS上黏附生长 ,SIS可促进 RRVEC的增殖 ,SIS对三种细胞的细胞周期和细胞凋亡率无影响。 SIS有良好的细胞相容性 ,其孔径、结构有助于 HEPOB、HESFB和 RRVEC细胞的黏附和生长 ,是良好的组织工程生物衍生材料。     

Amylolytic Activity of Small Intestinal Brush-Border Membrane in the Late Postresuscitation Period

Functional changes in the small intestinal brush-border membrane were studied in the late recovery period after acute fatal blood loss. Delayed recovery of enzyme activity in the small intestinal brush-border membrane was due to impaired functional topography of the digestive transport system. It was manifested in a shift of the proximodistal gradient toward reserve zones of the ileum.     

Spatiotemporal Organization of the Proliferative System in Small Intestinal Crypt Epithelium of Intact Mice

We studied spatiotemporal organization of the proliferative system in small intestinal crypt epithelium of normal mice. Close relationships were found between circadian rhythms of cell proliferation and their position in the crypt. These peculiarities reflected spatiotemporal organization of the crypt epithelium. The hierarchic structure of spatiotemporal organization suggests the existence of several interrelated levels (individual cells, cell subpopulations, and cells with basal and maximum levels of proliferation within subpopulation). Each level has its proper temporal and spatial characteristics. Their interaction determines spatiotemporal organization of the proliferative system in the small intestinal crypt epithelium.     

Contraction and Collapsing Kinetics of Single Synthetic Polymer Chains at Small Quench Depths

Chain contraction and collapsing kinetics of pyrene‐labeled poly(N‐isopropylacrylamide) (PNIPAM) single chains ( = 3.64 × 10⁵ g · mol^?1, = 1.17) were investigated by employing the stopped‐flow technique coupled with fluorescence and light scattering detections, which can achieve millisecond jumping of solvent quality from good to above and below the θ‐solvent condition at small quench depths. It was found that the coil‐to‐crumpled globule transition proceeds via an isotropic one stage process and the obtained characteristic relaxation times exhibit a monotonic decrease with increasing quench depths. The obtained experimental results were in qualitative agreement with previous theoretical considerations.

     

肠血管活性多肽或生长抑素抑制大鼠肠CD8~+淋巴细胞归巢

为观察肠血管活性多肽 (VIP )及生长抑素 (SST )对大鼠肠淋巴细胞在肠相关淋巴组织归巢的影响 ,本实验将 18只大鼠随机分为三组 ,每组 6只 ,分别从股静脉输入生理盐水、VIP组或SST ,从肠系膜淋巴管插管引流淋巴液。结果显示 ,大鼠经静滴VIP或SST后 ,5h内肠系膜淋巴管淋巴细胞总数降低 (P <0 0 5 ) ;肠淋巴液量和对照组比较无显著改变 (P >0 0 5 ) ;每毫升淋巴液中细胞数降低 (P <0 0 5 )。VIP组和SST组肠淋巴液中CD8+ 细胞比例降低 (P <0 0 5 )。两实验组回肠粘膜CD8+ 细胞数降低 (P <0 0 5 )。VIP或SST能减少肠粘膜CD8+ 淋巴细胞与其他器官及系统免疫的沟通 ,也抑制从其他器官及系统免疫中归巢至肠粘膜的CD8+ 细胞     

Ultrastructural Changes in Cells of the Gastric and Small Intestinal Mucosa during Bronchial Asthma

The complex of structural changes in the gastroduodenal mucosa in patients with bronchial asthma is considered as a polyetiological primary degenerative process with progressive atrophy of the epithelium and formation of erosions. Ultrastructural signs included degenerative changes in the endothelium of microvessels and surface and glandular epithelium, which were accompanied by compensatory hyperfunction of intact mucus-producing cells, hyperplasia, and increased functional activity of mast and immunocompetent cells. The development of destructive and erosive lesions was associated with hyperplasia of parietal and endocrine cells in the mucosa. We evaluated the specific structural reactions clinically typical of bronchial asthma of different severity. The data are interpreted in terms of a relationship between pathological changes in the mucosa of different localization.     

Colonic Motility in the Cat

Rostad , H. Colonic motility in the cat. V. Influence of telencephalic stimulation and the peripheral pathways mediating the effects. Acta physiol. scand. 1973. 89. 169–181. The cerebral cortex and intracerebral structures were stimulated in lightly anesthetized cats while colonic motility was recorded using extraluminal strain gage transducers. Excitatory colonic responses were produced from the anterior ectosylvian gyrus (the second somatic sensory-motor area) and from a small zone around the anterior end of the lateral sulcus. These effects were shown to be mediated through the vagal nerves. Colonic inhibition resulted from stimulation of three separate cortical zones, the anterior sigmoid, the orbital and the anterior cingulate gyrl These effects were mediated mainly through the lumbar colonic nerves. Stimulation of the amygdaloid nuclei produced excitatory colonic effects mediated through the lumbar colonic nerves. Inhibitory effects were not obtained from the amygdala. Finally, weak colonic contractions resulted from stimulation of the olfactory bulb and tract and were found to be conveyed through the parasympathetic vagal and pelvic nerves.     

Pallidosubthalamic projection in the Cat

Summary The degenerative changes within the cat's subthalamic nucleus (Sth) following lesions of the external pallidum were studied by electron microscopy.Four to five days following pallidal lesions a great number of terminals undergoing degenerative changes were encountered in the ipsilateral Sth. The contralateral Sth was free of degeneration. The degenerating terminals show predominantly the light degenerative type, less frequently the dark degenerative pattern, and occasionally exhibit signs of filamentous hyperplasia. The degenerated boutons usually insert on perikarya of the large Sth neurons, on proximal dendrites, and more rarely contact dendritic spines. They were observed neither to perform synaptic contacts with the perikarya of the small Sth neurons nor with other vesicle-containing profiles. On the basis of the ultrastructural aspect of the degenerating terminals, they were identified as F1 terminals, discriminated in a previous study (Romansky et al., 1978). The normal appearance, the synaptic relationships, and the degenerative features of the F1 terminals in the Sth closely resemble the entopeduncular terminals in the thalamus described by Rinvik and Grofová (1974a), and Grofová and Rinvik (1974).The possible contribution of the interrupted passing fibers to the observed degeneration is discussed. The present findings corroborate the relevant morphological, physiological, neurochemical, and neuropharmacological data in the literature.     

Analysis of the Expression of MICA in Small Intestinal Mucosa of Patients with Celiac Disease

The MHC class I chain-related A gene (MICA) is expressed in gastrointestinal epithelium and functions as an immune activation signal under stress conditions. MICA protein binds to NKG2D, a receptor of gamma delta T cells containing the TCR variable region V(delta)1, which are the most abundant subset of T cells in the intestinal epithelium. Ingested gluten in patients with celiac disease (CD) may function as a stress signal for the epithelial cells, and could enhance MICA expression on their surface. In this study, we have analyzed MICA expression in intestinal biopsy specimens from newly diagnosed and treated CD patients and controls. Quantitative RT-PCR analysis did not show differences in MICA expression among the three groups. With these results, we conclude that overexpression of MICA does not seem to play an important role in the pathogenesis of CD, at least at the time of diagnosis.