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Iberis amara L. belongs to the family of Brassicaceae, which is native to Southern Europe. It is a bloomer cultivated as an ornamental and medicinal plant. Iberis amara has pharmacological effects such as antioxidant, anti-insect, anti-inflammatory, anti-microbial, antiallergic, and anti-cancer effects. This plant is rich in essential oil, fatty oil, amines, glucosinolates, cucurbitacins, and flavonoids. Botanical description, medicine uses, the chemical compositions, and biological activities of Iberis amara are summarized in the present review. Iberis amara is an available and promising medicinal plant for pharmaceutical industries. The purpose of this review is to systematically describe the botanical characteristics, the chemical compositions, and biological activities of Iberis amara, hereby providing a scientific basis for the development of this plant in pharmaceutical applications. [ABSTRACT FROM AUTHOR]

Remodeling of Intestinal properties and hypersensitivity of intestinal afferents to mechanical stimulation were previously demonstrated in a fasting rat model. Other studies investigated the association between mechanical and histological remodeling during fasting. This study aimed to further explore the relationship between the jejunal remodeling and intestinal afferent hypersensitivity by combining afferent nerve recordings with histological and mechanical data. Eight male Sprague Dawley rats had no access to food for 7 days (Fasting group). Seven male rats served as controls (Control group). Jejunal segments were studied in vitro in an organ bath for analysis of afferent signaling and for analysis of mechanical and histomorphological parameters. Correlation analyses were done to analyze association between nerve activity (spike rate increase ratio, SRIR) at distension levels of 20, 40 and 80 cmH2O and mechanical stress and histomorphological changes of the jejunal segments. Compared with the Control group, the main findings in jejunal segments in the Fasting group were (1) Most histomorphometry parameters were reduced (P < 0.05–P < 0.001), (2) SRIR values were higher (P < 0.001), (3) The relative numbers of intermuscular and submucosal neurons were increased (P < 0.05–P < 0.01), and (4) SRIR was negatively correlated with intestinal wall thickness, circumferential muscle layer thickness and positively correlated with the inner residual strain, the number of neurons, and the mechanical stress. In conclusion, the fasting-induced histomorphological remodeling (reduced wall thickness and increased relative number of neurons) and biomechanical remodeling (residual strain changes and high stress level) of the intestine in fasting rats were associated with hypersensitivity of intestinal afferents. Afferent hypersensitivity appears to be dependent on stress rather than on strain. [ABSTRACT FROM AUTHOR]

Contractile patterns in rectum, puborectalis muscle and anal sphincter must be studied to understand defecation. Six subjects had contractile waveforms studied with Fecobionics. Symptom questionnaires, balloon expulsion test and anorectal manometry were done for reference. The Fecobionics bag was filled in rectum to urge-to-defecate volume and measurements were done for 4 h before the subjects attempted to evacuate the device. Pressures and bend angle (BA) variations were analyzed with Fast Fourier Transformation. Four normal subjects exhibited low frequency waves (< 0.06 Hz) for pressures and BA. The waves were uncoordinated between recordings, except for rear and bag pressures. Peak wave amplitudes occurred at 0.02–0.04 Hz. Pressures and the BA differed for peak 1 (p < 0.001) and peak 2 amplitudes (p < 0.005). The front pressure amplitude was bigger than the others (rear and BA, p < 0.05; bag, p < 0.005) for peak 1, and bigger than bag pressure (p < 0.005) and BA (p < 0.05) for peak 2. One subject was considered constipated with lower front pressure amplitudes compared to normal subjects and increased amplitudes for other parameters. The sixth subject was hyperreactive and differed from the other subjects. In conclusion, the rectum, anal sphincter and puborectalis muscle showed different contraction waves during prolonged measurements. The data call for larger studies to better understand normal defecation, feces-withholding patterns, and the implications on anorectal disorders. [ABSTRACT FROM AUTHOR]

Background: Only limited data exist on repeatability of anorectal studies with the established physiological and clinical technologies for assessment of anorectal function. Fecobionics is a new multi-sensor simulated feces that provide data by integrating elements from current tests. Aims: To study repeatability of anorectal data obtained with the Fecobionics device. Methods: We assessed the database of Fecobionics studies to determine how many repeated studies were done. From a total of 260 Fecobionics studies, 19 subjects with repeated studies using approximately the same protocol and prototype were identified. Key pressure and bending parameters were assessed and the repeatability analyzed using Bland Altman plots. Furthermore, the inter- and intra-individual coefficient of variation (CV) were computed. Results: Fifteen subjects (5F/10 M) with repeated studies were normal subjects, three were patients with fecal incontinence and one subject suffered from chronic constipation. The main analysis was conducted on the cohort of normal subjects. The bias for 11 parameters were within the confidence interval, whereas two were slightly outside. The interindividual CV was lowest for the bend angle (10.1–10.7) and between 16.3 and 51.6 for the pressure parameters. The intra-individual CVs were approximately half of the inter-individual CVs, spanning from 9.7 to 27.6. Conclusion: All data from normal subjects were within previously defined normality. The Fecobionics data showed acceptable repeatability with bias within the confidence limits for almost all parameters. The intra-individual CV was much lower than the inter-individual CV. Dedicated large-scale studies are warranted to evaluate the influence of age, sex, and disease on repeatability as well as comparing between technologies. [ABSTRACT FROM AUTHOR]

Fecobionics is an integrated device that has shown promise for assessment of anorectal function. We used a wireless Fecobionics prototype to visualize defecatory patterns and to compute volume–pressure, contraction work, and flow. Twelve normal subjects were studied. The probe was 10 cm-long and contained pressure sensors and electrodes for impedance planimetry. Pressures, diameters, and volume data during defecation were analyzed. The bag was distended inside rectum to the urge-to-defecate level where after the subjects were asked to evacuate. The contraction work and defecatory flow were computed from the volume changes during expulsion. The minimum anal diameter during the evacuation was 17.6 ± 1.5 mm. The middle diameter recording was 10–20% lower than the front diameter channels and 10–20% bigger than the rear channels. The bag volume at urge correlated with the minimum diameter (r = 0.63). The diameter-pressure and volume–pressure loops were counterclockwise with phases of bag filling, isometric contraction, ejection and anal passage. The defecatory contraction work was 3520 ± 480 mL × cmH2O. The maximum flow during defecation was 302 ± 33 mL/s. The flow was associated with the anal diameter (r = 0.84) but not with the rectoanal pressure gradient (r = 0.14). Volume–pressure loops have a tremendous impact on the understanding of cardiopulmonary pathophysiology. Future studies will shed light on potential clinical impact in defecatory pathophysiology. [ABSTRACT FROM AUTHOR]

Defecatory disorders including fecal incontinence (FI) are diagnosed on the symptom pattern supplemented by anorectal manometry (ARM), the balloon expulsion test (BET), and endo-anal ultrasonography. In this study, we used a simulated stool named Fecobionics to study distinct defecation patterns in FI patients using preload-afterload diagrams and to provide comparative data on defecation indices (DIs) between passive and urge incontinent patients. All subjects had Fecobionics, endo-anal ultrasonography and ARM-BET done. The Fecobionics bag was distended in rectum until urge in 37 female patients (64.1 ± 1.5 yrs) and a group of normal subjects (NS, 12F, age 64.8 ± 2.8 yrs). Rear-front pressure (preload-afterload) diagrams and DIs were compared between groups. The FISI score in the patients was 8.6 ± 0.6. The NS did not report FI-related symptoms. All patients and NS defecated Fecobionics and ARM-BET within 2 min. The urge volume was 46.1 ± 3.6 and 35.3 ± 5.9 mL in the FI and normal groups (P > 0.1). The expulsion duration was 14.8 ± 2.4 and 19.8 ± 5.1 s for the two groups (P > 0.1). The preload-afterload diagrams demonstrated clockwise loops that clearly differed between the FI subtypes and NS. The DIs showed profound difference between patients and NS. Fecobionics data showed higher correlation with symptoms in FI patients than ARM-BET. Fecobionics obtained novel pressure signatures in subtypes of FI patients and NS. Fecobionics provides DI data that cannot be obtained with ARM-BET. [ABSTRACT FROM AUTHOR]

It is well known that overload changes the mechanical properties of biological tissues and fasting changes the responsiveness of intestinal afferents. This study aimed to characterize the effect of overload on mechanosensitivity in mesenteric afferent nerves in normal and fasted Sprague–Dawley rats. Food was restricted for 7 days in the Fasting group. Jejunal whole afferent nerve firing was recorded during three distensions, i.e., ramp distension to 80 cmH2O luminal pressure (D1), sustained distension to 120 cmH2O for 2 min (D2), and again to 80 cmH2O (D3). Multiunit afferent recordings were separated into low-threshold (LT) and wide-dynamic-range (WDR) single-unit activity for D1 and D3. Intestinal deformation (strain), distension load (stress), and firing frequency of mesenteric afferent nerve bundles [spike rate increase ratio (SRIR)] were compared at 20 cmH2O and 40 cmH2O and maximum pressure levels among distensions and groups. SRIR and stress changes showed the same pattern in all distensions. The SRIR and stress were larger in the Fasting group compared to the Control group (P < 0.01). SRIR was lower in D3 compared to D1 in controls (P < 0.05) and fasting rats (P < 0.01). Total single units and LT were significantly lower in Fasting group than in Controls at D3. LT was significantly higher in D3 than in D1 in Controls. Furthermore, correlation was found between SRIR with stress (R = 0.653, P < 0.001). In conclusion, overload decreased afferent mechanosensitivity in a stress-dependent way and was most pronounced in fasting rats. Fasting shifts LT to WDR and high pressure shifts WDR to LT in response to mechanical stimulation. [ABSTRACT FROM AUTHOR]

Diverticulosis results from the development of pouch-like structures, called diverticula, over the colon. The etiology of the disease is poorly understood resulting in a lack of effective treatment approaches. It is well known that mechanical stress plays a major role in tissue remodeling, yet its role in diverticulosis has not been studied. Here, we used computational mechanics to investigate changes in stress distribution engendered over the colon tissue by the presence of a pouch-like structure. The objectives of the study were twofold: (1) observe how stress distribution changes around a single pouch and (2) evaluate how stress elevation correlates with the size of the pouch. Results showed that high stresses are concentrated around the neck of a pouch, and their values and propagation increase with the size of the pouch neck rather than the pouch surface area. These findings suggest that stress distribution may change in diverticulosis and a vicious cycle may occur where pouch size increases due to stress elevation, which in turn elevates stress further and so on. Significant luminal pressure reduction would be necessary to maintain stress at normal level according to our results and therapeutic approaches aimed directly at reducing stress should rather be sought after. [ABSTRACT FROM AUTHOR]

Intestinal afferents play an important role in coordinating intestinal motor control. Fasting induces morpho-mechanical intestinal remodeling. This study aimed to characterize the effect of fasting and refeeding on mechanosensitivity in mesenteric afferent nerves in isolated Sprague–Dawley rat jejunum. A control group fed ad libitum, a group fasted for 7 days and a group refed 7 days after 7 days fasting were studied. Jejunal segments were used for electrophysiological, histomorphological and mechanical studies. Mesenteric afferent nerve firing was recorded during a ramp distension up to 40 mmHg luminal pressure. Multiunit afferent recordings were separated into low threshold and wide-dynamic-range single-unit activity. Intestinal deformation (strain), bowel distension load (stress) and firing frequency of mesenteric afferent nerve bundles [spike rate increase ratio (SRIR)] were compared among groups. Fasting induced intestinal histomorphometric remodeling, which was reversed by refeeding. The firing frequency increased with distension in all groups. SRIR was largest in the fasting group (P < 0.05). Compared to the control group, fasting increased afferent activity in whole nerve bundles and wide-dynamic-range units at high degrees of distensions (P < 0.05 at pressure 40 mmHg; P < 0.05 at strain 1.2; P < 0.01 at stress 8 kPa). Refeeding reversed the fasting-induced afferent hypersensitivity and the shift between receptor subtypes. In conclusion, refeeding reversed fasting-induced remodeling. [ABSTRACT FROM AUTHOR]

Atherosclerosis is a major cause of mortalities and morbidities worldwide. It is associated with hyperlipidemia and inflammation, and become chronic by triggering metabolites in different metabolic pathways. Disturbance in the human gut microbiota is now considered a critical factor in the atherosclerosis. Trimethylamine-N-oxide (TMAO) attracts attention and is regarded as a vital contributor in the development of atherosclerosis. TMAO is generated from its dietary precursors choline, carnitine, and phosphatidylcholine by gut microbiota into an intermediate compound known as trimethylamine (TMA), which is then oxidized into TMAO by hepatic flavin monooxygenases. The present review focus on advances in TMAO preventing strategies through probiotics, including, modulation of gut microbiome, metabolomics profile, miRNA, or probiotic antagonistic abilities. Furthermore, possible recommendations based on relevant literature have been presented, which could be applied in probiotics and atherosclerosis-preventing strategies. [ABSTRACT FROM AUTHOR]

During defecation, solid, semisolid or liquid stools are eliminated via the anus in a complex physiological process. Up to 25% of the population are affected by anorectal disorders that are poorly recognized and treated. We developed a new bionics device, a simulated stool named Fecobionics, to replace several current tests of anorectal function. Fecobionics was developed to simulate the defecation process that depends on rectal forces, the anorectal size angle, and anorectal size and sensitivity. Fecobionics provided axial pressure signatures, measurement of bending (anorectal angle) and geometric mapping in a single examination. It had the consistency and shape of normal stool. The device had a soft core with embedded electronics and a bag for distension. The paper describes the device development and validation. Furthermore, data were obtained in preliminary experiments in pigs, healthy human subjects and patients with focus on four important features of the system, i.e. measurements of pressure signatures, bending characteristics, impedance measurements and data transmission. Accurate pressure and orientation data as well as geometric profiles were successfully obtained on the bench as well as in vivo in pigs and human subjects during defecation. Fecobionics is a novel technology imitating defecation. The clinical future ultimately depends on its ability to impact on daily treatment of anorectal disorders. A potential long-term clinical application is use of the device for biofeedback training for dyssynergic defecation. [ABSTRACT FROM AUTHOR]

Inhibitor of DNA binding 1 (Id1) has been shown to be involved in adipogenesis and metabolism, which may contribute to atherosclerotic progression. However, it remains unclear how Id1 regulates endothelial cell functions and atherosclerosis in response to oscillatory shear stress. The current study aims to evaluate the effects of oscillatory shear stress on LDL uptake by endothelial cells and to delineate the roles of Id1 in this process. Using an in vivo ligation model of ApoE−/− mice and applying low and oscillatory shear stress (OSS) in vitro, we found that OSS can effectively promote lipid uptake. In vivo en face staining results showed that OSS down-regulated Id1 expression. In vitro, OSS activated Id1 transiently but eventually inhibited its expression with time. Overexpression of Id1 can abolish OSS-mediated lipid uptake in ECs. In addition, Id1 overexpression and knockdown experiments demonstrated that Id1 can regulate LDLR expression to influence lipid uptake. Immunoprecipitation and subcellular localization results further suggested that Id1 can combine with sterol regulatory element-binding protein1 (SREBP1), which may be related to the Id1-mediated LDLR down-expression. Our study shows a biomechanical role of Id1 in endothelial cells’ uptake of lipid by down-regulating LDLR, which could help understand how oscillatory flow affects atherosclerotic development. [ABSTRACT FROM AUTHOR]

Intestinal obstruction prompts luminal dilation and wall remodeling proximal to the site of obstruction. Studies on temporal and spatial morphomechanical remodeling are needed for comprehending the pathophysiology of acute intestinal obstruction. The aim was to estimate the no-load and zero-stress morphomechanical properties in circumferential and longitudinal direction at 0, 6, 12, 24, 36, and 48 h after complete intestinal obstruction. Obstruction of the distal ileum was created surgically by placement of a polyethylene ring for up to 48 h in 30 rats. Sham and normal groups were also studied (n = 12). Five 6 cm-long intestinal segments proximal to the obstruction site were used for histological, morphometric and mechanical analysis at the designated times. Morphomechanical changes were huge but only subtle changes were observed between the 5 segments during the obstruction period. Due to dilation, the serosal length and mucosal length increased continuously from 6 to 48 h (p < 0.001). The wall area increased at 24 h and beyond (p < 0.001), demonstrating tissue growth. The opening and bending angle decreased to minimum values at 24 h where after the opening angle increased and the bending angle returned to pre-obstruction levels. For the residual stretch ratios and the position of the neutral axis the turning point was found after 24 h. Histologically, the thickness and area of most wall layers were quite stable for the first 12 h but with an increase at the 24 h time point that continued to the 48 h time point. The most pronounced change was found for the circumferential muscle layer (p < 0.05). Analysis of picrosirius red stained slides showed that submucosal type 3 collagen fraction increased significantly (p < 0.001), whereas the fraction of type 1 collagen decreased (p < 0.001). In conclusion, pronounced time-dependent morphomechanical remodeling was found. The obstructed intestine went from dilation remodeling to growth remodeling during the interval 12-24 h after creating the obstruction. [ABSTRACT FROM AUTHOR]

Purpose of Review The study aimed to discuss novel endoscopic approaches to resection of submucosal lesions. Recent Findings Endoscopic resection by excavation, full-thickness resection, and submucosal tunneling are by now well-documented techniques for submucosal tumor resection. Combined approaches with laparoscopy such as several variations of laparoscopic endoscopic cooperation surgery (LECS) and non-exposed wall-inversion surgery (NEWS) are also possible now. Reports of these approaches show good results. However, lesion size is the main limitation to these approaches. Summary Endoscopic submucosal tumor resection can be effectively done endoscopically or by endoscopy combined with laparoscopy. These techniques allow localized resection of lesions at difficult locations such as in the gastroesophageal junction with limited influence on the normal anatomy. Variations in techniques are being practiced worldwide striving to achieve complete resection with minimal disturbance of function or contamination. The choice between approaches depends largely on the size and site of the lesion and expertise available. [ABSTRACT FROM AUTHOR]

Short-term feeding with low-fiber diet remodels the mechanomorphological properties in the rabbit small intestine. The aims were to study the effect of feeding low-fiber diet for 5 months on mechanomorphological properties including the collagen fraction in the rabbit intestines. Fifteen rabbits were divided into an Intervention group (IG, n = 10) fed a low-fiber diet and a Control group (CG, n = 5) fed a normal diet for 5 months. Five months later, four 10-cm-long segments obtained from the duodenum, jejunum, ileum and large intestine were used for histological and mechanical analysis, respectively. The wall thickness, wall area, mucosa and muscle layer thickness decreased whereas the submucosa layer thickness increased in the IG ( p < 0.05). The collagen fraction decreased in all layers and segments in the IG ( p < 0.05). The opening angle increased in the large intestine and decreased in the ileum in the IG ( p < 0.05). The intestinal stress-strain curves for IG shifted to the right, indicating softening. The creep did not change in the four segments. The wall stiffness was associated with wall thickness and collagen fraction in the submucosa layer. Long-term low-fiber diet in rabbits induced histomorphometric and biomechanical remodelling of the intestines. [ABSTRACT FROM AUTHOR]

Background: Opioid analgesics inhibit anal sphincter function and contribute to opioid-induced bowel dysfunction (OIBD). However, it is unknown whether the inhibition can be reduced by opioid antagonism with prolonged-release (PR) naloxone and how this compares to laxative treatment.Aims: To compare the effects of combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350 on anal sphincter function and gastrointestinal symptoms.Methods: A randomized, double-blind, crossover trial was conducted in 20 healthy men. Participants were treated for 5 days with combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350. Resting anal pressure, anal canal distensibility, and relaxation of the internal sphincter to rectal distension were evaluated before treatment (baseline) and on day 5. The Patient Assessment of Constipation Symptom (PAC-SYM) questionnaire, stool frequency, and stool consistency were assessed daily.Results: Both PR oxycodone/naloxone and PR oxycodone plus macrogol treatment decreased sphincter relaxation compared to baseline (- 27.5%; P < 0.001 and - 14.7%; P = 0.01). However, sphincter relaxation was increased after PR naloxone/oxycodone treatment compared to macrogol (difference = + 17.6%; P < 0.001). Resting anal pressure and anal canal distensibility did not differ between treatments. PAC-SYM abdominal symptoms score was lower during PR naloxone compared to macrogol (0.2 vs. 3.2; P = 0.002). The number of bowel movements was lower during PR naloxone versus macrogol (4.2 vs. 5.4; P = 0.035).Conclusion: Relaxation of the internal anal sphincter was significantly better after PR oxycodone/naloxone treatment compared to PR oxycodone plus macrogol 3350. These findings highlight that OIBD may require specific therapy against the complex, pan-intestinal effects of opioids. [ABSTRACT FROM AUTHOR]

Significant stress softening recovery after potassium chloride (KCl) administration was previously demonstrated in the intact rat esophageal wall. The aim of this study is to investigate the effect of KCl activation on stress softening recovery in the separated mucosa-submucosa layer and muscle layer of rat esophagus. Three series of loading-unloading distensions were carried out on 10 rat esophagi where the two separated layers were distended at luminal pressure levels 0.5, 1.0 and 2.0 kPa. Numerous distension cycles were done in $$\hbox {Ca}^{2+}$$ -free Krebs solution before and after activation with KCl (110 mmol) for 3 min in calcium-containing media. The diameter and luminal pressure were recorded for stress and strain calculation. During KCl activation, the muscle layer responded with a high-amplitude contraction, and the mucosa-submucosa layer responded with a longer-lasting low-amplitude contraction. The hysteresis loop areas from the muscle layer were significantly bigger than those from the mucosa-submucosa layer at distension pressures 1.0 and 2.0 kPa ( $${F}>4.9, {p}<0.001$$ ). The calculated stiffness in the mucosa-submucosa layer was significantly higher than that in the muscle layer ( $${p}<0.001$$ ). After activation with KCl, the stored energy and the stiffness after the stress and viscoelasticity softening increased in both layers, indicating that the reversible stress softening in esophagus after KCl activation is existed in both layers. [ABSTRACT FROM AUTHOR]

A number of factors influence gastrointestinal tissue structure and mechanical properties such as the physical environment and diseases like partial obstruction. Hence multi-axial biomechanical properties are important for understanding the pathophysiology of the obstructed intestine. The aim was to estimate the multi-axial biomechanical properties, in particular with focus on the shear modulus. Partial obstruction of mid-jejunum was created surgically by placement of a polyethylene ring for two weeks in seven male rats. Sham operation was made in five other rats. At the time for termination, three 6-cm intestinal segments were used for histological and mechanical analysis. The segments were obtained distal (S1), proximal (S2) and further proximal (S3) to the site of obstruction or suturing site. The tri-axial testing included simultaneous torsion, inflation and longitudinal stretching. The lumen size, wall thickness, wall cross-sectional area, and muscle layer thickness increased in S2 and S3 of the obstructed rats ( p < 0.001) with the most pronounced changes in S2. The opening angle decreased in S2 in the obstructed group ( p < 0.05). The tissue stiffness increased in circumferential and longitudinal direction where as it was softer in shear direction, especially in S2 ( p < 0.01). In conclusion, the histomorphological and mechanical properties including shear properties remodeled proximal to the intestinal obstruction site. [ABSTRACT FROM AUTHOR]

Symptoms related to functional and sensory abnormalities are frequently encountered in patients with diabetes mellitus. Most symptoms are associated with impaired gastric and intestinal function. In this review, we discuss basic concepts of sensory-motor dysfunction and how they relate to clinical findings and gastrointestinal abnormalities that are commonly seen in diabetes. In addition, we review techniques that are available for investigating the autonomic nervous system, neuroimaging and neurophysiology of sensory-motor function. Such technological advances, while not readily available in the clinical setting, may facilitate stratification and individualization of therapy in diabetic patients in the future. Unraveling the structural, mechanical, and sensory remodeling in diabetes disease is based on a multidisciplinary approach that can bridge the knowledge from a variety of scientific disciplines. The final goal is to increase the understanding of the damage to GI structures and to sensory processing of symptoms, in order to assist clinicians with developing an optimal mechanics based treatment. [ABSTRACT FROM AUTHOR]

This nonsystematic review aims to describe recent developments in the use of functional lumen imaging in the gastrointestinal tract stimulated by the introduction of the functional lumen imaging probe. When ingested food in liquid and solid form is transported along the gastrointestinal tract, sphincters provide an important role in the flow and control of these contents. Inadequate function of sphincters is the basis of many gastrointestinal diseases. Despite this, traditional methods of sphincter diagnosis and measurement such as fluoroscopy, manometry, and the barostat are limited in what they can tell us. It has long been thought that measurement of sphincter function through resistance to distension is a better approach, now more commonly known as distensibility testing. The functional lumen imaging probe is the first medical measurement device that purports in a practical way to provide geometric profiling and measurement of distensibility in sphincters. With use of impedance planimetry, an axial series of cross-sectional areas and pressure in a catheter-mounted allantoid bag are used for the calculation of distensibility parameters. The technique has been trialed in many valvular areas of the gastrointestinal tract, including the upper esophageal sphincter, the esophagogastric junction, and the anorectal region. It has shown potential in the biomechanical assessment of sphincter function and characterization of swallowing disorders, gastroesophageal reflux disease, eosinophilic esophagitis, achalasia, and fecal incontinence. From this early work, the functional lumen imaging technique has the potential to contribute to a better and more physiological understanding of narrowing regions in the gastrointestinal tract in general and sphincters in particular. [ABSTRACT FROM AUTHOR]

Background and Aims: Differences in contraction characteristics between primary and secondary peristalsis have only been scarcely studied. Recently new measures of contractile activity in the human esophagus were developed. The study aims were to use combined manometry and impedance planimetry [pressure-cross-sectional area (P-CSA)] recordings from healthy volunteers to examine esophageal peristalsis, and, furthermore, to investigate the effect of the motility enhancing drug erythromycin to study differential effects on the two types of contractions. Methods: Sixteen healthy volunteers participated in the study [mean age 23 (range, 19-34) years, 6 females]. An esophageal probe with a bag for CSA measurement was positioned 10 cm above the lower esophageal sphincter. Bag volume was increased stepwise from 5 to 25 ml before and after intravenous infusion of 250 mg erythromycin. Swallow-evoked primary and distension-evoked secondary esophageal peristalsis were compared with regard to (1) pressure amplitude, (2) CSA amplitude, (3) preload tension (wall tension before an evoked contraction), (4) contractile tension, and (5) work outputs. Results: Primary peristalsis induced more efficient contractions as the contraction amplitudes, work output and contractile tension were higher compared to secondary peristalsis ( P < 0.001). Erythromycin induced change in CSA during distension-evoked secondary peristalsis (CSA before 212.9 ± 26.8 vs. after 180.5 ± 23.3, P < 0.05). The sensitivity to esophageal distension increased with the distending volume both before and during erythromycin. The sensitivity was not changed by erythromycin ( P = 0.6). Conclusions: Esophageal primary peristaltic contractions were more forceful with longer duration, and higher work output compared to secondary peristalsis contractions. Erythromycin affected peristalsis only to a minor degree. [ABSTRACT FROM AUTHOR]

Strain/stress induced tissue softening is usually referred to irreversible softening. The aim of this study was to investigate whether stress softening in rat esophagus is reversible after potassium chloride (KCl) induced contraction. Three series of inflation-deflation loadings were carried out on esophageal specimens obtained from 20 Wistar rats. All specimens were subjected to the first two series in Ca-free Krebs solution(Krebs) and then incubated in Ca-containing Krebs solution (Krebs) for 1 h. Ten specimens were distended to pressure 1.0 kPa and activated with KCl for 3 min. The other ten specimens, however, were distended to 1.0 kPa without KCl activation. Subsequently, after incubation in Krebs for 1 h, all 20 specimens were subjected to the third series testing. The stored energy in the esophageal tissues (hysteresis loop area) and the esophageal wall stiffness were compared between two groups within the three series loadings. Results indicated that incubation in Krebs cannot recover the stress softening induced energy and stiffness loss, but in contrast, these loss were recovered markedly ( p < 0.05) after KCl activation. In conclusion, stress softening in rat esophagus is reversible after the activation of KCl-induced contractions. This mechanism could be related to regeneration of tissue properties in rat esophagus. [ABSTRACT FROM AUTHOR]

Previous numerical simulations on low-density lipoprotein (LDL) concentration polarization in the arterial system indicated that LDL concentration polarization might play an important role in the genesis and development of atherosclerosis. To date, no in vivo experiments have examined this question directly, and the molecular mechanisms are unknown. In this study, ten rabbits were treated with gel-silica loop to develop a defined local stenosis in the straight segment of the left carotid artery. Both numerical simulation and experiment measurements showed that the concentration of LDL was about 35% higher at the blood/arterial wall interface than in the lumen on the distal side of the stenosis. Atherosclerotic lesions with abundant lipid deposits were observed and stromal derived factor-1 (SDF-1) was detected at the distal end of the stenosis, while the straight segment was plaque-free. In vitro studies demonstrated that LDL-induced SDF-1 expression in endothelial cells and increased monocyte adhesion to endothelial cells in a dose-dependent manner. The adhesion was suppressed when endothelial cells were pretreated with SDF-1 antibody. These results suggested LDL concentration polarization contributed to the localization of atherosclerosis and to the expression of SDF-1. In turn, SDF-1 facilitated plaque formation. [ABSTRACT FROM AUTHOR]

Background and Aims: Gastrointestinal disorders and symptoms are common in diabetic patients. Advanced glycation end-products (AGEs) and their receptor (RAGE) have been proposed as an important pathological mechanism underlying diabetic complications, such as diabetic cardiopathy, retinopathy, nephropathy, etc. The aims were to study the distribution of AGE and RAGE in the normal and diabetic small intestine and colon in rats and the possible relationship between AGEs/RAGE and diabetes-induced intestinal structural remodeling. Methods: Diabetic and age-matched normal rats survived for 56 days. The body weight and blood glucose were measured regularly until day 56. Jejunal, ileal, and colonic segments were excised. The wet weight per unit length and the layer thickness were measured. AGE and RAGE were detected by immunohistochemical staining. Results: The wet weight per unit length in the three segments and the layer thickness in jejunum and ileum increased in the diabetic rats. The staining density of AGE in diabetic rats was higher in the villi of jejunum and ileum, and in the crypt and circumferential muscle layer of ileum compared to normal rats. The staining intensity of RAGE increased in ganglia, crypt, and brush border of diabetic jejunum and ileum as well as in ganglia of diabetic colon. Positive association was found between the accumulation of AGE and RAGE and the thickness of the different layers. Conclusions: The expression of AGE and RAGE is up-regulated in the small intestine and colon of diabetic rats. The increased AGE and RAGE levels may contribute to diabetic GI dysfunction. [ABSTRACT FROM AUTHOR]

Background: Systemic sclerosis (SS) patients with severe esophageal affection have impaired peristalsis. However, motor function evaluated in vivo by manometry and fluoroscopy does not provide detailed information about the individual contraction cycles.Aims: To apply, for the first time in gastrointestinal (GI) patients, a method and principles modified from cardiac research to study esophageal muscle behavior in SS patients.Methods: Muscle contraction cycles were analyzed using pressure-cross-sectional area (P-CSA) loops during distension pressure up to 5 kPa. The probe with bag and electrodes for CSA measurements was positioned 7 and 15 cm above the lower esophageal sphincter (LES) in eleven healthy volunteers and eleven SS patients. The P-CSA, the wall tension, Δtension (afterload tension - preload tension), contraction velocity, work output (area of the tension-CSA loops), and power output (preload tension × CSA rate) were analyzed.Results: The P-CSA loops consisted of phases with relaxation and contraction behavior. The tension-stretch ratio loops in patients were shifted to the left at both distension sites, indicative of a stiffer wall in patients. Lower contraction amplitudes and smaller P-CSA loops were observed for the SS patients. The work output, power output, Δtension, and contraction velocity were lower in patients (P < 0.001). Association was found between disease duration and the work output, Δtension, and velocity at pressure steps higher than 3 kPa (P < 0.05).Conclusions: Distension-evoked esophageal contraction can be studied in vivo and analyzed with advanced methods. Increased esophageal stiffness and impaired muscle function that depended on disease duration were observed for SS patients. The analysis may be useful for characterization of other diseases affecting GI function. [ABSTRACT FROM AUTHOR]

Both mechanical and ischemic mechanisms can cause gastrointestinal pain. We investigated whether discomfort and pain caused by bag distension in the esophagus of healthy subjects correlated best with mechanical forces (stress), deformation (strain), or mucosal perfusion. Twenty-nine subjects underwent ramp bag distension using a novel catheter design incorporating high-frequency intraluminal ultrasound, laser Doppler flowmetry, and manometry. Perfusion, pressure, and geometric data were analyzed at visual analog scale (VAS) levels 1-7 in 19 subjects. The circumferential stress increased exponentially as a function of volume, whereas strain showed a linear increase. The perfusion showed a modest decline, on average 15% from baseline to VAS = 7. A significant association was found between the sensory response and stress and strain (P < 0.05). No significant association was found between the sensory response and perfusion. In conclusion, the discomfort and pain response to bag distension in the esophagus is likely to be caused by mechanical rather than ischemic mechanisms. [ABSTRACT FROM AUTHOR]

The histomorphologic and passive biomechanical properties were studied in the mid-colon of 16 non-diabetic and 20 streptozotocin (STZ)-induced diabetic rats (50 mg/kg STZ, ip). The diabetic rats were divided into groups living 4 and 8 weeks after the induction of diabetes (n = 10 for each group). The mechanical test was a ramp distension of fluid into the colon in vitro. The colon diameter and length were obtained from digitized images of the segments at pre-selected pressures and at the no-load and zero-stress states. Circumferential and longitudinal stresses and strains were computed from the length, diameter, and pressure data and from the zero-stress state geometry. The blood glucose level increased 3-4-fold in the diabetic rats compared with the controls (P < 0.001). Diabetes generated pronounced increases in the colon weight per length, wall thickness, and wall cross-sectional area (P < 0.001). Histologically, the thickness of all layers was increased during diabetes (P < 0.05), especially the mucosa layer. The opening angle, and absolute values of residual strain increased in the diabetic group (P < 0.05 and P < 0.01, respectively). Furthermore, diabetes increased the circumferential and longitudinal stiffness of the colon wall (P < 0.001). The observed changes in residual strain, opening angle, and stress-strain relation may be contributing factors to colonic dysfunction and abdominal pain in diabetic patients. [ABSTRACT FROM AUTHOR]

This study aimed to investigate wound geometry and tissue damage caused by several different trocar types using a quantitative functional luminal imaging probe (FLIP) geometric profile and histomorphologic analysis. Four pigs were used in this study. After general anesthesia, six different trocars were randomly inserted at preselected locations in the porcine abdominal wall. The hydration status of the animals was monitored and maintained. A bag mounted on a FLIP was used to profile the geometry of the trocar holes during distension. After the FLIP study, the abdominal wall surrounding the trocar holes was harvested. The tissue was fixed in neutral 10% buffered formalin solution for more than 24 h. The samples contained control tissue (undamaged) and test tissue (damaged) through the entire rectangular tissue block. Approximately four to seven slides were cut parallel to the surface from each sample. Each slide was photographed, and the morphometry of the hole and damaged areas were measured and displayed three-dimensionally. The histologic sections were analyzed with regard to acute damage, bleeding, and acute inflammation of the skin, muscle, and fascia. The FLIP study demonstrated differences between the six trocars. These were mainly due to differences between the Versaport Plus V2 bladed trocar with the smooth cannula, the Applied Medical Separator nonbladed access system with threaded cannula, and the VersaStep Plus trocar. The morphometry data showed the smallest hole and damage areas for the Versaport Plus V2 bladed trocar with the smooth cannula. The damaged area divided by the trocar hole area was smallest for the VersaStep plus trocar and the Ethicon Endopath bladed trocar with a stability cannula ( p < 0.05). The histologic analysis showed that the VersaStep Plus trocar and the Ethicon Endopath bladed trocar with a stability cannula gave the least bleeding and inflammation ( p < 0.05). An agreement was found between the geometric data obtained by FLIP, the morphometric analysis, and the histology. [ABSTRACT FROM AUTHOR]

Most studies on the effect of aging on esophageal motor function have shown that peristaltic function deteriorates with age. Esophageal motor function is traditionally studied by means of manometry and radiography. Distension of the esophagus with evaluation of active and passive mechanical parameters have become available during recent years. In this study, we did a manometric swallow analysis and used the distension method to study esophageal properties and function during aging. An impedance planimetric probe with a bag for distension was placed in the distal esophagus of 25 healthy volunteers with a median age of 35 (range 23-86) years. Distensions were done at an infusion rate of 25 ml min(-1) with and without relaxation of neuromuscular activity with butylscopolamine. The infusion was reversed when moderate pain was experienced by the subjects. Swallow-induced contraction amplitudes decreased as function of age for persons older than 40 years (P < 0.05). The total and passive tension showed an exponential increase as function of the change in radius, whereas the active tension increased until it reached a local maximum point. The maximum active tension deteriorated as a function of age after the age of 40 years (P < 0.05). Furthermore, esophagus became stiffer with age. In conclusion, age-related changes of increased stiffness and reduced primary and secondary peristalsis were found in the human esophagus with a deterioration of esophageal function after the age of 40 years. Such changes may contribute to the high prevalence of reflux disease in elderly. [ABSTRACT FROM AUTHOR]

The function of the small intestine is to a large degree mechanical, and it has the capability of deforming its shape by generating phasic (short-lasting) and tonic (sustained) contraction of the smooth muscle layers. The aim of this study was to obtain phasic and tonic stress-strain (normalized force-length) curves during distension of isolated rat jejunum and ileum (somewhat similar to the isometric length-tension diagram known from in vitro studies of muscle strips). We hypothesized that the circumferential stress-strain data depend on longitudinal stretch of the intestine. Intestinal segments were isolated from ten Wistar rats and put into an organ bath containing 37 degrees C aerated Krebs solution. Ramp distension was done on active and passive intestinal segments at longitudinal stretch ratios of 0, 10, and 20%. Ramp pressures from 0 to 7.5 cmH(2)O were applied to the intestinal lumen at each longitudinal stretch ratio. Passive conditions were obtained by adding the calcium antagonist papaverine to the solution. Total and passive circumferential stress and strain were computed from the length, diameter and pressure data and from the zero-stress state geometry. The active stress was defined as the total stress minus the passive stress. The total and passive circumferential stresses increased exponentially as a function of the strain. The amplitude of both the total and passive stress was biggest in the jejunum. The total circumferential stress decreased whereas the passive circumferential stress increased when the intestine was stretched longitudinally. Consequently, longitudinal stretching caused the active circumferential stress to decrease. The passive circumferential stress during longitudinal stretching increased more in the jejunum than in the ileum. Therefore, the active circumferential stress decreased most in the jejunum. In conclusion, the circumferential active-passive stress and strain depend on the longitudinal stretch and differs between the jejunum and ileum. [ABSTRACT FROM AUTHOR]

Our aims were to investigate gender differences to multimodal stimulations of the esophagus after experimentally induced sensitization. Thirty healthy age-matched subjects, 13 males and 17 females, were included. Pain evoked by mechanical and thermal stimuli was assessed before and after perfusion of the lower esophagus with 0.1 N hydrochloric acid. Males were more sensitive to the baseline mechanical stimuli (P < 0.01) and tolerated a lower volume of acid (P = 0.04). After acid perfusion, males were more sensitive than females to distensions (cross-sectional area P = 0.001 and volume P = 0.001). Acid perfusion sensitized both males (P = 0.03) and females (P = 0.04) to heat stimulation but not to cold stimulation (males, P = 0.09; females, P = 0.8). The referral areas for pain evoked by mechanical and thermal stimuli were larger in females compared with males both before and after acid perfusion (P = 0.002). In females only the referred pain area increased to heat stimulations (P = 0.02). Acid infusion resulted in a more hyperreactive esophagus (P = 0.03) but the hyperreactivity was not gender-dependent. In conclusion, males were more sensitive to mechanical and chemical esophageal stimuli and showed acid-evoked mechanical hyperalgesia. Females had significantly larger referred pain areas to the stimulations. The differentiated response to peripheral and central pain mechanisms may explain the gender-related differences seen in several gastrointestinal disorders. [ABSTRACT FROM AUTHOR]

To understand the physiology and pathology of the esophagus, it is necessary to know the mechanical properties and their dependence on the structural components. The aim of this study was to investigate the effect of collagenase and elastase on the morphological and biomechanical properties in the no-load and zero-stress states in the rat esophagus. Twenty tissue rings from each esophagus of seven normal rats were sectioned in an organ bath containing calcium-free Krebs solution with dextran and EGTA. After the rings were photographed in the no-load state, 8 of the 20 rings were separated into mucosa-submucosa and muscle rings and the rings were transferred to four different solutions containing collagenase, elastase, or corresponding control solutions. The rings were cut radially to obtain the zero-stress state and photographed again. The thickness, area, and opening angle were measured from the digitized images. The collagen and elastin area fractions were determined from histological slides with Van Gieson and Weigert's elastic stain. The opening angles and residual strain did not differ in the nonseparated enzyme-treated rings and control rings. However, in the separated mucosa-submucosa ring the opening angle was significantly smaller after treatment than that in control rings (P < 0.01). Collagenase and elastase reduced collagen and elastin in the mucosa-submucosa layer about 40% in the nonseparated wall and 54% in the separated mucosa-submucosa layer (P < 0.01). Collagenase and elastase increased the thickness in the separated mucosa-submucosa layer compared to the control (P < 0.05). Disconnection between the epithelia and the lamina propria was histologically observed after elastase digestion. In conclusion, collagenase and elastase caused the opening angle and the residual strain in the separated mucosa-submucosa layer to decrease. The opening angle of the separated mucosa-submucosa layer depended to some extent on the fraction of collagen and elastin. [ABSTRACT FROM AUTHOR]

It is uncertain to what degree sensation and pain relating to the gut are influenced by sex. The aim of the study was to explore sex differences to experimental multimodal stimulation of the esophagus in 22 age-matched males and females. A probe was positioned in the lower part of the esophagus. Mechanical stimuli were applied as distensions with a bag using an impedance planimetric method. The distensions were done before and after relaxation of the smooth muscle. Thermal stimulation was done with recirculating water at 1 and 60°C in the bag. The sensory intensities were assessed during the stimulations, and the referred pain area was drawn at maximum pain intensities. An increased sensation to mechanical stimuli was found in the males for volume, pressure, and tension ( P=0.003, P=0.02, P=0.005), whereas cross-sectional area and strain showed no sex difference ( P=0.06, P=0.9). Sex differences were not found for the cold and warmth stimulations ( P=0.6, P=0.1). The mean size of the referred pain areas to the different stimuli was 23.6 cm2 in males and 48.7 cm2 in females ( P=0.002). As strain is believed to be the major determinant for the sensory response to mechanical stimulation of the gut, we conclude that no robust sex differences were observed in the assessments of the multimodal stimulations. However, the larger referred pain area in females reflects sex differences in central pain processing, which may explain the female preponderance in functional disorders relating to the gut. [ABSTRACT FROM AUTHOR]

Diabetes is associated with remodeling of the morphology and elastic properties of the small intestine. This study aims to study remodeling of the viscoelastic (time-dependent) properties of the small intestine during experimental diabetes. Stress relaxation tests were performed on the duodenum, jejunum, and ileum in 10 nondiabetic and 28 streptozotocin (STZ) -induced diabetic rats. The rats were made diabetic by a single intraperitoneal injection of 50 mg/kg STZ. The diabetic rats were allocated into groups living four days or one, two, or four weeks after the induction of diabetes (N = 7 in each group). The mechanical test was performed using a machine that rapidly stretched the intestinal tube to 40% more than the resting length. The intestinal diameter and wall area were obtained from digitized images of the intestinal segments at no-load and zero-stress states. The stress (force per area) was computed and a reduced-stress relaxation function was applied. The log decay parameter C and the slow and fast time constants τ[sub i] and τ[sub 2] were computed. STZ-induced diabetes was associated with a progressive increase in the wall thickness and wall cross-sectional area (P < 0.05). τ[sub i] and τ[sub 2] increased and C decreased. The slope α became consistently less negative (P < 0.05), and the stress after 600-sec relaxation gradually increased during diabetes (P < 0.01). In conclusion, the viscoelastic behavior of the intestinal wall changed during the development of diabetes. [ABSTRACT FROM AUTHOR]

The current study aimed to refine the conventional distension model in the human rectum by measuring the cross-sectional area with a ramp-controlled impedance planimetric system. After preconditioning, the rectum in seven volunteers was distended 56 times with infusion rates of 50, 100 and 200 ml/min and at 100 ml/min during relaxation of the smooth muscle with glucagon. The pump was reversed at maximal tolerated pain. The subjects tolerated a higher volume and pressure with a more reliable sensory rating after preconditioning of the tissue. The three distension rates resulted in different pressure and tension at the maximal pain intensity (P < 0.02 and P < 0.05) with a decrease after relaxation of the smooth muscle with glucagon (P < 0.05). On the other hand, the cross-sectional area and volume were robust, did not show strain-rate dependency, and were not affected by muscle relaxation. Since the cross-sectional area is directly related to the deformation of the gut wall and hence to the strain, the study supports the idea that, independent of the muscular function, the mechano sensitive nociceptors in the human rectum depend directly on circumferential wall strain rather than on pressure and tension. [ABSTRACT FROM AUTHOR]

Systemic treatment with epidermal growth factor (EGF) induce growth of the large intestine. The aim of this study was to investigate the morphological properties early in the course of EGF-induced large intestinal growth. The effects of systemic EGF treatment on the morphological properties at the zero-stress state along the large intestine were investigated. EGF-treated rats and control rats were allocated into group with EGF treatment for 2, 4, 7, and 14 days (N = 6 for each EGF treatment group except N = 4 for the 14-day group). The controls had saline injected (N = 3 for each group). The excised large intestine was subdivided into four segments: the ascending colon, transverse colon, descending colon, and rectum. The length and weight of each segment was measured. The zero-stress state was obtained by cutting rings of the large intestine radially, and the opening angle was measued on video images. The thickness and cross-sectional area of the mucosa and muscle layers, and the inner and outer circumference were measured. The total colon length did not increase, whereas the weight of the large intestine, muscosal thickness and mass, and inner and outer circumference increased significantly (P < 0.05). The increase was most prominent in the proximal colon after 7 days of EGF treatment. Later no further morphological changes were observed, except for a decrease in mucosal thickness in most segments and in mucosal cross-sectional area in the descending colon. In the controls and during the first week of EGF treatment, the opening angle was approximately 100 degrees. After 14 days the opening angle increased significantly in the ascending and transverse colon to approximately 172 and 135 degrees (P < 0.05). In conclusion, this study demonstrates that systemic EGF treatment caused remodeling of the morphology of the zero-stress state in the large intestine in a time-dependent manner. The growth was most pronounced in the ascending and transverse colon and involved mainly the mucosal layer. [ABSTRACT FROM AUTHOR]

Radiotherapy of malignancies in the pelvis is associated with both early and late intestinal reactions with subsequent alterations in rectal function because this part of the intestine often is included in the radiation field. This report presents data on morphometry of the zero-stress and no-load states as well as residual strains and opening angles of the rectum in mice with early and late radiation injury and in age-matched sham-irradiated control groups. In blood vessels and esophagus, cross-sections at the zero-stress state are not closed rings, but open sectors. The rectal zero-stress state is demonstrated by cutting the rectum into rings and cutting the rings into sectors; each sector is characterized by an opening angle. The opening angle was between 50 degrees and 200 degrees and differed between groups (P < 0.01). Young mice had 25-50% smaller opening angles than the older mice. The irradiated groups had 25-75% smaller opening angles than the normal groups. The residual strain analysis showed mucosal compression and serosal tension in the no-load state. Both at the serosal and mucosal surfaces, variation was found between groups (P < 0.01). The no-load state wall thickness-to-mucosal circumferential length ratio varied along the axis of the organ (P < 0.01) and between groups (P < 0.01). The early irradiated group had higher values than the control group. Furthermore, proximal to the irradiated zone the late irradiated group had significantly higher values compared to the normal group, indicating a higher stress level proximal to the irradiated zone. The zero-stress state must be taken into account when studying pathophysiological problems in which the stresses and strains are important, eg, the storage function of the rectum. Radiation therapy and age remodeled the morphometry and zero-stress state of rectum. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Tension-strain relations and morphometric data were studied in isolated segments of the jejunum and distal ileum in untreated diabetic rats, insulin-treated diabetic rats, and nondiabetic control rats. Diabetes was induced by a single intravenous injection of streptozotocin (28 mg/kg body wt). All injected rats developed hyperglycemia. The experiment was terminated after 28 days and the intestinal segments were superfused with saline solution containing papaverine to abolish contractile activity. Stepwise inflation of a balloon in which the cross-sectional area (CSA) was measured provided the luminal pressure-loading stimulus. The circumferential tension-strain relation was derived from steady-state values of internal radius and applied pressure. The intestinal weight, length, and weight per unit length increased significantly in untreated diabetic rats compared to the two other groups (P < 0.05). The body weight decreased in untreated diabetic rats compared to the two other groups (P < 0.05). The pressure-CSA relations differed between jejunum and distal ileum (P < 0.001) but not between the groups (P > 0.2). The tension-strain relations in jejunum and distal ileum were nonlinear and the curves for the two diabetic groups were shifted to the left compared to the curve for controls (P < 0.05), indicating increased wall stiffness. The histomorphometric data showed increased wall thickness in untreated diabetic rats compared to the two other groups both in jejunum and distal ileum (P < 0.02). Mucosal, submucosal, and muscle layer thicknesses did not differ between the three groups. No significant association was found between the histomorphometric and biomechanical parameters. [ABSTRACT FROM AUTHOR]

The morphometry at no-load and zero-stress states and residual circumferential strains were determined along the pig duodenum in vitro in seven pigs. The no-load state was obtained by cutting eleven 2-mm-wide rings at 10% intervals along the duodenum. The zero-stress state was obtained by cutting the rings radially. The zero-stress state provides a standard morphological state to describe tissue since internal and external forces do not affect the tissue. The morphometric measures were obtained from digitized images, and the layer thicknesses were measured from histological sections. The mucosal and serosal circumferences, the wall thickness, and the wall thickness-to-mucosal radius ratio were largest in the proximal end of the duodenum (f > 1.9, P < 0.05). The thickness of the submucosal stratum compactum layer and the opening angle increased in distal direction (f = 2.3, P < 0.05 and = 6.5, P < 0.001). The residual strain at the mucosal surface was negative, indicating that the mucosa-submucosa layers of duodenum in no-load state are in compression. Distension experiments showed that the residual strain makes the stress distribution through the wall more uniform in the pressurized state. In conclusion, the large circumferential residual strains must be taken into account in the study of physiological problems, in which the stresses and strains are important, eg, the bolus transport function. [ABSTRACT FROM AUTHOR]

The dose- and time-dependent effects ofendoscopic sclerotherapy on luminal cross-sectional areaand wall distensibility were studied in pigs at 5 and 12cm proximal to the gastroesophageal junction by means of impedance planimetry. Sixteen healthyanimals underwent two sessions of endoscopicsclerotherapy two weeks apart with injections of either5 or 10 ml of 1% Polidocanol in the distal 7 cm of the esophagus each time. The animals wereinvestigated before sclerotherapy, two weeks after eachsession, and finally six weeks after the last session.Six healthy animals were studied as controls. Endoscopic sclerotherapy caused luminal narrowing in thesclerosed zone followed by normalization six weeks afterthe last treatment (P < 0.05 in both groups). Walldistensibility decreased in the sclerosed zone after treatment with 10 ml sclerosant (P <0.05) followed by partial normalization, while no effectwas found after 5 ml sclerosant (P > 0.2).Progressive dilations were observed in the proximalesophagus in both groups and were most pronounced in the10 ml group (P < 0.05). Wall distensibility did notchange proximal to the site of sclerotherapy in eithergroup (P > 0.1). [ABSTRACT FROM AUTHOR]

This study was designed to evaluate the distensibility and secondary peristalsis of the esophagus in patients suffering from systemic sclerosis with severe esophageal involvement. Balloon distension with impedance planimetric measurement of luminal cross-sectional area was done 7 and 15 cm above the lower esophageal sphincter in 13 patients and nine healthy controls. The controls were studied both with and without receiving the anticholinergic drug butylscopolamine. The cross-sectional area--pressure relations were nonlinear with the largest cross-sectional area in patients at both measuring sites when compared to controls (P < 0.001). The anticholinergic drug butylscopolamine increased the cross-sectional area in controls (P < 0.001). The cross-sectional area distensibility, defined as CSA0(-1) delta CSA delta P-1 did not differ between patients and controls. Balloon distensions elicited contractions proximal to the distension site. The amplitude and frequency of contractions at the distal distension site were significantly reduced in the patients when compared to the controls (P < 0.05). In conclusion, the distal esophagus is most severely affected in patients with systemic sclerosis with increased cross-sectional area and impaired peristalsis. [ABSTRACT FROM AUTHOR]

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