Mucin gene expression in human embryonic and fetal intestine

Background—The intestinal epithelium is coveredby a continuous layer of mucus which is secreted by well differentiatedepithelial cells. Disregulation of the expression of mucins has beenreported to have possible implications in the neoplastic process which affects intestinal mucosae. It is well known that preneoplastic andneoplastic tissues can express fetal phenotypic characteristics.
Aims—To assess whether the expression of mucingenes in the intestinal tract is linked to the stage of cellulardifferentiation and tissue development, by studying the expression ofsix mucin genes in human fetal small intestine and colon, and alsoadult tissues.
Methods—In situ hybridisation was used to studymRNA expression of MUC2, MUC3, MUC4, MUC5B, MUC5AC, and MUC6 in 32 human embryos and fetuses (6.5-27 weeks gestation). Normal adultmucosae were used as controls.
Results—Three mucin genes, MUC2, MUC4, andMUC5AC, were differently expressed in fetal intestine compared withexpression in normal adults.
Conclusion—These differences in mucin geneexpression suggest a possible regulatory role for these products inintestinal epithelial cell differentiation.

Keywords:mucin genes; mucins; intestine; differentiation; human fetus

     

Morphometric and Biomechanical Intestinal Remodeling Induced by Fasting in Rats

The function of the small intestine is mechanical to a large degree. To understand the function it is necessary to know how the mechanical stresses and strains can be computed. Nutrition plays an important role in the maintenance of normal gut structure and function. The small intestine undergoes functional changes when food is withheld. To explore the morphological and biomechanical remodeling during starvation, intestinal segments from the fed and fasted rat duodenum, jejunum, and ileum were investigated. After seven days of fasting the animals lost 22% of the body weight and the intestinal mass per length decreased by nearly 40% in the duodenum. Fasting decreased the plasma levels of glucose, insulin, triglyceride, and cholesterol whereas the level of free fatty acids increased (P < 0.001). Fasting decreased the outer circumferential length, wall thickness, wall area, inner circumferential length, and luminal area at the three locations (P < 0.001). Histological examination showed that the mucosal and the submucosal thickness decreased during fasting (P < 0.001), whereas the muscle layers were unchanged. The residual strain on the mucosal surface was compressive. The serosal residual strain was tensile and increased with the highest values after four days of fasting in the duodenum and jejunum (P < 0.001). Fasting shifted the stress–strain curves to the right in both circumferential and longitudinal directions at the three locations (P < 0.04). In conclusion pronounced biomechanical and structural remodeling occurred in the small intestine during fasting for up to one week. Since the contractile properties depend on the passive properties (according to the well-known Hill's model), it can be predicted that the smooth muscle contractile function will also change.     

The development of the fetal rat intestine and its reaction to maternal diabetes. I. Morphometrical analysis in normal conditions

In rodents, the fetal intestine develops rapidly during the last 5 days of gestation. The present investigation describes the events which occur in the duodenum, jejunum and ileum of fetal Wistar rat from day 16.5 to 21.5. The first villi and microvilli as well as endocrine cells already appear at 17.5 days in the duodenal mucosae. Goblet cells are detected at 18.5 days. The structure of the intestinal mucosa at 21.5 days is similar to that of adults. The evolution was quantified by morphometric analysis. The external and inner circumference, the length of the villi profile and the increased absorption area due to the villi profile were measured. We demonstrated that the total enlargement of the luminal surface area due to the villi and the microvilli in the duodenum of the fetus at 21.5 days is similar to that in the adult duodenum. This morphometric analysis could be used to detect possible disturbances in the development of the fetal intestine.     

Intestinal regrowth is amplified after jejunal but not ileal resection during tapeworm infection in the rat

The ileum possesses functions required by a healthy individual that are not fully supplanted by the duodenum or jejunum. Evidence suggests that the ileum may also be necessary to maintain an enteric parasite–host interaction. We hypothesized that the ileum is essential to the survival of the lumen-dwelling, rat tapeworm, H. diminuta. Male rats were divided into three groups: those with ileal or jejunal resections and nonresected controls. Half of each rat group was infected with the tapeworm. After jejunal resection, the weight but not length of intestinal remnant (duodenum + ileum) in infected rats returned to that of control, nonresected intestine 29 days after surgery and tapeworm numbers were fully maintained. In contrast, after ileal removal intestinal length and weight of the remaining duodenum and jejunum in infected rats were significantly decreased and tapeworm survival diminished. Data indicates that intestinal growth following resection is amplified by tapeworm infection when the ileum remains but diminished when the ileum is removed. Furthermore, loss of the ileum results in decreased infection intensity and dry weight of the tapeworm.     

Nanoscale buckling deformation in layered copolymer materials

In layered materials, a common mode of deformation involves buckling of the layers under tensile deformation in the direction perpendicular to the layers. The instability mechanism, which operates in elastic materials from geological to nanometer scales, involves the elastic contrast between different layers. In a regular stacking of "hard" and "soft" layers, the tensile stress is first accommodated by a large deformation of the soft layers. The inhibited Poisson contraction results in a compressive stress in the direction transverse to the tensile deformation axis. The hard layers sustain this transverse compression until buckling takes place and results in an undulated structure. Using molecular simulations, we demonstrate this scenario for a material made of triblock copolymers. The buckling deformation is observed to take place at the nanoscale, at a wavelength that depends on strain rate. In contrast to what is commonly assumed, the wavelength of the undulation is not determined by defects in the microstructure. Rather, it results from kinetic effects, with a competition between the rate of strain and the growth rate of the instability.     

Modeling the Microstructure Curvature of Boron-Doped Silicon in Bulk Micromachined Accelerometer

Microstructure curvature, or buckling, is observed in the micromachining of silicon sensors because of the doping of impurities for realizing certain electrical and mechanical processes. This behavior can be a key source of error in inertial sensors. Therefore, identifying the factors that influence the buckling value is important in designing MEMS devices. In this study, the curvature in the proof mass of an accelerometer is modeled as a multilayered solid model. Modeling is performed according to the characteristics of the solid diffusion mechanism in the bulk-dissolved wafer process (BDWP) based on the self-stopped etch technique. Moreover, the proposed multilayered solid model is established as an equivalent composite structure formed by a group of thin layers that are glued together. Each layer has a different Young’s modulus value and each undergoes different volume shrinkage strain owing to boron doping in silicon. Observations of five groups of proof mass blocks of accelerometers suggest that the theoretical model is effective in determining the buckling value of a fabricated structure.     

Implementation of a polling protocol for predicting celiac disease in videocapsule analysis

AIM: To investigate the presence of small intestinal villous atrophy in celiac disease patients from quantitative analysis of videocapsule image sequences.METHODS: Nine celiac patient data with biopsy-proven villous atrophy and seven control patient data lacking villous atrophy were used for analysis. Celiacs had biopsy-proven disease with scores of Marsh II-IIIC except in the case of one hemophiliac patient. At four small intestinal levels (duodenal bulb, distal duodenum, jejunum, and ileum), video clips of length 200 frames (100 s) were analyzed. Twenty-four measurements were used for image characterization. These measurements were determined by quantitatively processing the videocapsule images via techniques for texture analysis, motility estimation, volumetric reconstruction using shape-from-shading principles, and image transformation. Each automated measurement method, or automaton, was polled as to whether or not villous atrophy was present in the small intestine, indicating celiac disease. Each automaton’s vote was determined based upon an optimized parameter threshold level, with the threshold levels being determined from prior data. A prediction of villous atrophy was made if it received the majority of votes (≥ 13), while no prediction was made for tie votes (12-12). Thus each set of images was classified as being from either a celiac disease patient or from a control patient.RESULTS: Separated by intestinal level, the overall sensitivity of automata polling for predicting villous atrophy and hence celiac disease was 83.9%, while the specificity was 92.9%, and the overall accuracy of automata-based polling was 88.1%. The method of image transformation yielded the highest sensitivity at 93.8%, while the method of texture analysis using subbands had the highest specificity at 76.0%. Similar results of prediction were observed at all four small intestinal locations, but there were more tie votes at location 4 (ileum). Incorrect prediction which reduced sensitivity occurred for two celiac patients with Marsh type II pattern, which is characterized by crypt hyperplasia, but normal villous architecture. Pooled from all levels, there was a mean of 14.31 ± 3.28 automaton votes for celiac vs 9.67 ± 3.31 automaton votes for control when celiac patient data was analyzed (P < 0.001). Pooled from all levels, there was a mean of 9.71 ± 2.8128 automaton votes for celiac vs 14.32 ± 2.7931 automaton votes for control when control patient data was analyzed (P < 0.001).CONCLUSION: Automata-based polling may be useful to indicate presence of mucosal atrophy, indicative of celiac disease, across the entire small bowel, though this must be confirmed in a larger patient set. Since the method is quantitative and automated, it can potentially eliminate observer bias and enable the detection of subtle abnormality in patients lacking a clear diagnosis. Our paradigm was found to be more efficacious at proximal small intestinal locations, which may suggest a greater presence and severity of villous atrophy at proximal as compared with distal locations.     

Reorganization of columnar architecture in the growing visual cortex

Many cortical areas increase in size considerably during postnatal development, progressively displacing neuronal cell bodies from each other. At present, little is known about how cortical growth affects the development of neuronal circuits. Here, in acute and chronic experiments, we study the layout of ocular dominance (OD) columns in cat primary visual cortex during a period of substantial postnatal growth. We find that despite a considerable size increase of primary visual cortext, the spacing between columns is largely preserved. In contrast, their spatial arrangement changes systematically over this period. Whereas in young animals columns are more band-like, layouts become more isotropic in mature animals. We propose a novel mechanism of growth-induced reorganization that is based on the “zigzag instability,” a dynamical instability observed in several inanimate pattern forming systems. We argue that this mechanism is inherent to a wide class of models for the activity-dependent formation of OD columns. Analyzing one representative of this class, the Elastic Network model, we show that this mechanism can account for the preservation of column spacing and the specific mode of reorganization of OD columns that we observe. We conclude that column width is preserved by systematic reorganization of neuronal selectivities during cortical expansion and that this reorganization is well described by the zigzag instability. Our work suggests that cortical circuits may remain plastic for an extended period in development to facilitate the modification of neuronal circuits to adjust for cortical growth.     

The value of double-contrast study of the small intestine in immunoproliferative small intestinal disease

Radiological findings of 2 patients with immunoproliferative small intestinal disease were studied. One of the cases was associated with alpha-chain disease. Both patients complained of severe diarrhea, and diagnosis was made by endoscopic biopsy of the duodenum and jejunum. Double-contrast studies of the small intestine and hypotonic duodenographies in these patients revealed thickened folds and innumerable fine granular elevations without ulcerations or luminal narrowings. Double-contrast studies are one of the most important examinations in the diagnosis of this disorder.     

Elasticity and wrinkled morphology of Bacillus subtilis pellicles

Wrinkled morphology is a distinctive phenotype observed in mature biofilms produced by a great number of bacteria. Here we study the formation of macroscopic structures (wrinkles and folds) observed during the maturation of Bacillus subtilis pellicles in relation to their mechanical response. We show how the mechanical buckling instability can explain their formation. By performing simple tests, we highlight the role of confining geometry and growth in determining the symmetry of wrinkles. We also experimentally demonstrate that the pellicles are soft elastic materials for small deformations induced by a tensile device. The wrinkled structures are then described by using the equations of elastic plates, which include the growth process as a simple parameter representing biomass production. This growth controls buckling instability, which triggers the formation of wrinkles. We also describe how the structure of ripples is modified when capillary effects are dominant. Finally, the experiments performed on a mutant strain indicate that the presence of an extracellular matrix is required to maintain a connective and elastic pellicle.     

弓形虫对猪小肠IEL数量与细胞因子表达的影响

目的研究弓形虫对猪小肠上皮内淋巴细胞（intraepithelial lymphocytes,IEL）数量、IL-10、IFN-γ和IL-12表达水平的影响。方法对疑似患弓形虫病的家猪,经临床观察、弓形虫血清学检测、病理剖检检查和病理组织学观察诊断,确诊5头弓形虫感染猪（感染组）和5头正常猪（对照组）;采用HE染色检测小肠IEL数量和免疫组织化学方法检测IL-10、IFN-γ和IL-12的表达。结果弓形虫血清学检测阳性,且在病变组织观察到弓形虫速殖子或假包囊,确诊病猪所患为弓形虫病;与对照组比较,感染组猪的空肠、回肠IEL数量明显增加（P〈0．01）,十二指肠IL-10、十二指肠和空肠IFN-γ、十二指肠和回肠IL-12的表达降低（P〈0．01）,回肠IL-10和1FN-γ的表达亦降低（P〈0．05）。结论弓形虫感染猪小肠IEL数量增多,Th2型细胞因子IL-10和Th1型细胞因子IFN-γ、IL-12表达均降低,推测弓形虫调控IEL及其细胞因子,引起肠道黏膜免疫抑制,弓形虫入侵后维持肠道内环境平衡,说明IEL在抗弓形虫感染中并未起到积极作用。     

Synthesis of insulin-like growth factor II (IGF-II) in fetal rat tissues: translation of IGF-II ribonucleic acid and processing of pre-pro-IGF-II

The single insulin-like growth factor II (IGF-II) gene is transcribed into multiple RNA species in most fetal and neonatal rat tissues. For IGF-II to serve as a local growth factor in fetal tissues, IGF-II RNA must be translated into pre-pro-rat (r) IGF-II, and the biosynthetic precursor processed to smaller biologically active forms. IGF-II RNA extracted from fetal rat liver, muscle, intestine, lung, and stomach, from rat placenta, and from fetal or neonatal mouse liver and lung directed the synthesis of 22,000 mol wt pre-pro-IGF-II in a reticulocyte lysate cell-free translation system. A biosynthetic precursor of this size had been observed previously in translation of RNA from BRL-3A rat liver cells and is predicted by the nucleotide sequence of cDNA clones encoding rIGF-II. Consistent with the developmental pattern of expression of IGF-II RNA observed in hybridization studies, RNA from adult rat liver, muscle, and intestine did not direct the synthesis of pre-pro-rIGF-II. To determine whether the IGF-II biosynthetic precursor was processed to smaller biologically active IGF-II, term fetal rat tissues were extracted with acid-ethanol, the extracts were fractionated by acid gel filtration, and the IGF pools were examined in a RIA specific for IGF-II. Levels of 1-2 micrograms/g were observed in liver, limb, lung, intestine, and brain; lower levels were observed in heart and kidney. In general, the levels of immunoreactive IGF-II corresponded to the levels of IGF-II mRNA. These results suggest that IGF-II mRNA is translated, and pre-pro-IGF-II processed to mature IGF-II in different fetal rat tissues. In contrast to IGF-I, in which alternative RNA splicing generates possible precursor molecules containing different COOH-terminal propeptide segments, we find no evidence for an IGF-II precursor in rat tissues other than 22,000 mol wt pre-pro-rIGF-II.     

Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range

The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.     

Modelling Strategies for Reinforced Concrete Elements under Corrosion Degradation

Aging and corrosion of reinforced concrete structures (RCS) is becoming a global problem, thus proper procedures for simulating the structural performance of corroded RCS should be assessed. Among the main corrosion effects, concrete cover cracking and reinforcement cross-section reduction may influence the materials’ constitutive laws, moreover the confinement contribution and the lateral instability of the longitudinal rebars can be modified. In the present paper, the predictive models available in the scientific literature to assess the materials’ mechanical properties of corroded RCS are recalled and employed into a novel model to derive the theoretical moment–curvature relationships for the cross-section of square and rectangular corroded reinforced concrete elements. The model accounts for cover spalling, buckling of longitudinal reinforcing bars, reduction in confinement pressures, reduction in concrete constitutive law due to the concrete cracking induced by rust formation and decay of mechanical properties for corroded reinforcements. The obtained results are compared with the classical simplified models for corroded RCS, highlighting that buckling and confinement variations cannot be disregarded into a reliable modelling strategy, especially when local ductility plays a key role in the performed investigations.     

Fibrogenesis and fibrosis in inflammatory bowel diseases: Good and bad side of same coin?

Fibrogenesis in inflammatory bowel diseases is a complex phenomenon aimed at mucosal repair. However, it may provoke intestinal fibrosis with the development of strictures which require surgery. Therefore, fibrogenesis may be considered as a “two-faced” process when related to chronic intestinal inflammation. Many types of cells may be converted into the fibrogenic phenotype at different levels of the intestinal wall. A complex interaction of cytokines, adhesion molecules and growth factors is involved in the process. We report an overview of recent advances in molecular mechanisms of stricturizing Crohn’s disease (CD) including the potential role of trasforming growth factor beta, protein kinase C and Ras, Raf and ERK proteins. Fibrotic growth factors such as vascular endothelial growth factor and platelet-derived growth factor, as well as the Endothelial-to-Mesenchymal Transition induced by transforming growth factor-β, are considered. Finally, our experience, focused on tumor necrosis factor α (the main cytokine of inflammatory bowel diseases) and the link between syndecan 1 (a heparan sulphate adhesion molecule) and basic fibroblast growth factor (a strong stimulator of collagen synthesis) is described. We hypothesize a possible molecular pattern for mucosal healing as well as how its deregulation could be involved in fibrotic complications of CD. A final clinical point is the importance of performing an accurate evaluation of the presence of fibrotic strictures before starting anti-tumor necrosis α treatment, which could worsen the lesions.     

Wireless Video Capsule Enteroscopy in Preclinical Studies: Methodical Design of Its Applicability in Experimental Pigs

The aim of this project was to develop a methodology to introduce wireless video capsule endoscopy in preclinical research. Five mature female pigs (Sus scrofa domestica) were selected for the study. Capsule endoscopes (the EndoCapsule system; Olympus) were introduced into the duodenum endoscopically in each of the animals. The life span of batteries (i.e., total time of endoscopy recording) was 487–540 min (median 492 min). The capsule endoscope reached the cecum during enteroscopy once (after 7 h 57 min), in the remaining cases, endoscopy recordings terminated in the distal or terminal ileum. All capsule enteroscopies found a normal pattern of the small intestine. The intestinal lumen is narrower, transverse folds are sparse or even absent, villi are wider but less prominent in pigs compared to humans. Capsule endoscopy in experimental pigs will be helpful for future trials on injury of different drugs and xenobiotics to the small bowel.     

Distribution and Properties of Neutral Ceramidase Activity in Rat Intestinal Tract

Ceramide plays an important role in regulating cell proliferation and apoptosis. Recent studies indicate that generation of ceramide in the intestine from sphingomyelin hydrolysis may be implicated in colon cancer development. The enzymes that catalyze the further hydrolysis of ceramide in the intestine have, however, not been well investigated. Our data reveal the existence of a ceramidase (EC 3.5.1.23) in rat intestinal mucosa with an optimal pH of 7.0. One milligram of mucosal protein is able to hydrolyze 44.0 ± 9.6 nmol of ceramide in 1 hr. The activity is low in the proximal duodenum and increases to a plateau in the proximal jejunum. The activity is then similar throughout the small intestine, until it declines in the distal part of ileum. Some activity is also detectable in the colon. The activity increases slightly in the presence of monomeric bile salt concentrations and sharply at the critical micellar concentration. Similar patterns were observed for both primary (taurocholate) and secondary (taurodeoxycholate) bile salts. The addition of Triton X-100 enhances the ceramidase activity at optimal bile salt concentration. The reaction is linear with time for the first 20 min and the hydrolytic rate declines slowly thereafter. Finally, the activity shows a considerable resistance against tryptic degradation, as 71% of the ceramidase activity remained when the homogenates were preincubated with high concentrations of trypsin. Intestinal mucosa also has a ceramide synthesis activity, with a distribution pattern generally paralleling ceramide hydrolysis activity. In conclusion, intestinal neutral ceramidase has a distinct distribution pattern and bile salt dependence, which enables it to collaborate with intestinal sphingomyelinase in hydrolysis of sphingomyelin.     

Effect of the central nervous system on mucosal growth and apoptosis in the small intestine

Recently our studies have demonstrated that the central nervous system regulates in part mucosal cell growth and apoptosis in the rat small intestine. Ornithine decarboxylase (ODC) activity is a key enzyme for polyamine synthesis which plays an important role for the intestinal mucosal growth. We have demonstrated that the increase of ODC activity in the duodenum just before the dark period is abolished by truncal vagotomy and that the infusion of 2-deoxy-D-glucose into the third cerebroventricle activates ODC activity in the small intestine. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. Our preliminary data showed that intestinal mucosal apoptosis decreased in the ventromedial-hypothalamus-lesioned rat. These results indicate that the central nervous system, in addition to local factors, is related to regulation of mucosal homeostasis in the intestinal mucosa.