Histomorphometry and Strain Distribution in Pig Duodenum with Reference to Zero-Stress State

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 f = 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.     

Morphological properties and residual strain along the small intestine in rats

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine ( n =11). METHODS: To approach the no-load state, the intestine was surgically excised, transferred to an organ bath and cut transversely into short ring-shaped segments. Each ring was cut radially for obtaining the zero-stress state. The residual stress can be characterised by an opening angle. The strain difference between the zero-stress state and the no-load state is called residual strain. RESULTS: Large morphometric variations were found along the small intestine. The wall thickness was highest in the proximal duodenum and decreased in distal direction along the axis of the small intestine (P<0.001). The circumferential length of the inner and outer surfaces decreased rapidly along the length of duodenum by 30-50% (P<0.001). The wall area and lumen area showed a similar pattern (P<0.001). In zero-stress state the rings always opened up after making the cut. The experiments resulted in larger inner circumferential length and smaller outer circumferential length when compared to the no-load state. The wall thickness and wall area did not differ between the no-load and zero-stress state. The opening angle and tangent rotation angle increased along the length of the duodenum and had its highest value 30% down the intestine. Further down the intestine it decreased again (P<0.001). The serosal residual strain was tensile with the highest value close to the ligament of Treitz (P<0.001). The mucosal residual strain was compressive in all segments of the small intestine with average values between -0.25 and -0.4 and with the lowest values close to the ligament of Treitz (P<0.001). CONCLUSION: Axial variation in morphometric properties and residual strains were found in the small intestine. Existence of large residual strains indicates that the zero-stress state must be considered in future biomechanical studies in the gastrointestinal tract.     

Biomechanical and morphometric intestinal remodelling during experimental diabetes in rats

Aims/hypothesis Morphometric and passive biomechanical properties were studied in the duodenum, jejunum and ileum in 10 non-diabetic and 40 streptozotocin-induced diabetic rats.Methods The diabetic rats were divided into groups living 4 days, 1, 2, and 4 weeks after diabetes was induced (n=10 for each groups). The mechanical test was done as a ramp distension experiment. The intestinal diameter and length were obtained from digitised images of the intestinal segments at pre-selected pressures and at no-load and zero-stress states. Circumferential and longitudinal stresses (force per area) and strains (deformation) were computed from the length, diameter and pressure data and from the zero-stress state geometry.Results The blood glucose concentration increased four- to fivefold in the diabetic rats. Streptozotocin-induced diabetes generated pronounced increase in the weight per centimetre length, wall thickness and wall cross-sectional area in all intestinal segments during diabetes (p<0.05). Histological analysis showed that the thickness of the intestinal layers was increased in all segments during diabetes (p<0.05). In the duodenum the opening angle did not change in the first 2 weeks and decreased after 4 weeks (p<0.05). In the jejunum and ileum the opening angle increased after 1 week in the diabetic group. The residual strain showed the same pattern as the opening angle. Furthermore, it was found that the circumferential and longitudinal stiffness of the intestinal wall increased with the duration of diabetes (p<0.05 and p<0.01).Conclusion/interpretation Morphological and biomechanical remodelling of the small intestine occurred during the development of diabetes.Abbreviations GI Gastrointestinal - STZ streptozotocin     

Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

Small intestinal obstruction is a frequently encountered clinical problem. To understand the mechanisms behind obstruction and the clinical consequences, data are needed on the relation between the morphologic and biomechanical remodeling that takes place in the intestinal wall during chronic obstruction. We sought to determine the effect of partial obstruction on mechanical and morphologic properties of the guinea pig small intestine. Partial obstruction was created surgically in 2 groups of animals living for 2 and 4 weeks. Controls were sham operated and lived for 4 weeks. A combined impedance planimetry–high-frequency ultrasound system was designed to measure the luminal cross-sectional area and wall thickness. These measures were used to compute the circumferential stress and strain of the excised intestinal segments. The incremental elastic modulus was obtained by using nonlinear fitting of the stress–strain curve. Histologic analysis and the measurements of total wall collagen were also performed. The luminal cross-sectional area, wall thickness, and elastic modulus in circumferential direction increased in a time-dependent manner proximal to the obstruction site (P < 0.01), whereas no differences in these parameters were found distal to the obstruction site (P > 0.25). The circumferential stress–strain curves of the proximal segments in 2- and 4-week groups shifted to the left, indicating the intestinal wall became stiffer. Histologic examination revealed a massive increase in the thickness of the muscle layer especially the circular smooth muscle layer (P < 0.05). The collagen content proximal to the obstruction site was significantly larger in the partially obstructed animals compared to controls (P < 0.05). No difference was found distal to the obstruction site. Strong correlation was found between the collagen content and the elastic modulus at stress levels of 70 kPa stress (P < 0.01) and 10 kPa (P < 0.05) proximal to the obstruction site suggesting that the alteration of collagen has great impact on the mechanical remodeling. The morphologic and biomechanical remodeling likely influence the function of the intestine affected by partial obstructed intestine.     

Tension–Strain Relations and Morphometry of Rat Small Intestine in Experimental Diabetes

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.     

Remodelling of zero-stress state of small intestine in streptozotocin-induced diabetic rats. Effect of gliclazide

BACKGROUND: Biomechanical properties in terms of residual strains in diabetic small intestine have not been studied. Furthermore, no data have been reported on affect of gliclazide on gastrointestinal complications of diabetes. AIMS: To determine remodelling of zero-stress state of small intestine in streptozotocin-induced diabetic rats and effect of gliclazide treatment. MATERIALS: Morphological properties and residual strains were studied in duodenum, jejunum and ileum obtained from diabetic rats, gliclazide-treated diabetic rats and normal rats (n = 8 each group). METHODS: Diabetes was induced by single intraperitoneal injection of 65 mg/kg streptozotocin. Gliclazide (10 mg kg(-1) day(-1) was injected directly into stomach lumen by intragastric gavage twice daily. Experimental period was 35 days. To approach no-load state; intestinal segments were surgically excised and cut transversely into short ring-shaped segments. Each ring was cut radially to obtain geometry of zero-stress state. Circumferential length, the wall thickness and opening angle were measured from digital images of each specimen and residual strains were computed. RESULTS: Blood glucose level of diabetic group (approximately 20 mmol/l) was consistently higher than that in normal group (approximately 4 mmol/l) after induction of diabetes (p < 0.001). Gliclazide lowered average blood glucose level to between 10 and 15 mmol/l (p < 0.001). Plasma insulin levels of both diabetic groups (average between 10 and 15 pmol/l) were significantly lower than those in normal group (average approximately 18 pmol/l, p < 0.05). Wet weight per unit length and wall thickness of duodenum, jejunum and ileum were significantly higher in Diabetes group than those in Normal group (p < 0.05). Opening angle and absolute value of residual strain were significantly smaller in duodenum and larger in jejunum and ileum in Diabetes group than in Normal group (p < 0.001). Gliclazide treatment partly restored these changes (p < 0.05). CONCLUSIONS: Diabetes induced morphometric and biomechanical remodelling in intestine. Gliclazide partly restored these changes.     

Morphological properties and residual strain along the stroll intestine in rats

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine ( n = 11 )METHODS: To approach the no-load state, the intestine wassurgically excised, transferred to an organ bath and cuttransversely into short ring-shaped segments. Each ringwas cut radially for obtaining the zero-stress state. Theresidual stress can he characterised by an opening angle.The strain difference between the zero-stress state and theno-load state is called residual strain.RESULTS: Large morphometric variations were found along thesmall intestine. The wall thickness was highest in the proximalduodenum and decreased in distal direction along the axis of the small intestine ( P ＜ 0. 00l ). The circumferential length of the inner and outer surfaces decreased rapidly along the lengthof duodenum by 30-50 % (P＜0.001). The wall area and lumenarea showed a similar pattem( P ＜ 0.001 ). In zen-stress statethe dngs always opened up after making the cut. Theexperiments resulted in larger inner cirumferential length andsmaller outer circtmferential length when compared to the no-load state. The wall thickness and wall area did not differbetween the no-load and zero-stress state. The opening angleand tangent rotation angle increased along the length of theduodenum and had its highest value 30 % down the intestine.Further down the intestine it decreased again (P＜0.001). Theserosal residual strain was tensile with the highest value closeto the ligament of Treitz (P ＜ 0.001 ). The mucosal residualstrain was compressive in all segments of the small intestinewith average values between -0.25 and -0.4 and with the lowestvalues close to the ligament of Treitz ( P＜ 0.001 ).CONCLUSION: Axial variation in morphometric propertiesand residual strains were found in the small intestine.Existence of large residual strains indicates that the zero-stress state must he considered in future biomechanicalstudies in the gastrointestinal tract.     

Effect of Kaiyu Qingwei Jianji on the morphometry and residual strain distribution of small intestine in experimental diabetic rats

INTRODUCTION Dysfunction of upper gastrointestinal tract (GI) is common among diabetic patients[1]. As many as 75% of patients visiting diabetes clinics report significant GI Symptoms[2,3]. Common complaints include dysphagia, early satiety, reflux, abdominal pain, nausea, vomiting, and diarrhea[2,3]. As with other complications of diabetes, the duration of the disorder and poor glycemic control seem to be associated with more severe GI problems[2,3]. Histologically, many experiments h…     

Intestinal Damage in Strongyloidiasis: The Imbalance Between Cell Death and Proliferation

Strongyloidiasis is an endemic tropical parasitosis caused by Strongyloides stercoralis that also affects immigrants in nontropical countries. The nematode colonizes the duodenum and upper jejunum, inducing mucosal alterations. Because integrity is essential for a functional barrier, we aimed to study apoptosis and proliferation in the small bowel epithelium infected with S. stercoralis. We evaluated 23 patients and 17 controls. Apoptotic cells were detected by TUNEL and M30 immunolabelling, whereas proliferation was scored by Ki67 immunostaining and mitotic counting. Infection increased apoptotic indices in duodenum and jejunum (P < 0.001). Conversely, it decreased cell proliferation in both segments (P < 0.001). Our results showed that intestinal strongyloidiasis promotes an imbalance between cell death and proliferation. This is the first evidence of disruption of the epithelial kinetics with S. stercoralis infection, though the mechanisms remain unclear. Furthermore, our results support the idea that strongyloidiasis disturbs the mucosal integrity and can compromise the intestinal barrier.     

Early and late effects of irradiation on morphometry and residual strain of mouse rectum

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° and 200° 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.     

Phasic and Tonic Stress–Strain Data Obtained in Intact Intestinal Segment In Vitro

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.     

Ultrasound-Determined Geometric and Biomechanical Properties of the Human Duodenum

Methods based on cross-sectional ultrasound imaging may be valuable for assessment of biomechanical parameters in the duodenum in health and disease. In 12 healthy volunteers a specially designed duodenal bag containing a high-frequency ultrasound probe was inflated until the perception of moderate pain. The ultrasound images and bag pressures were recorded before and after administration of butylscopolamine. The duodenum approached a circular shape as the load was increased (P = 0.01). The tension-strain relations were exponential and the curve fitting constant α (stiffness) was 1.72±0.81 before and 1.13±0.22 after administration of butylscopolamine (P=0.5). In three subjects construction of stress-strain diagrams was possible. The wall thickness decreased after administration of butylscopolamine (P < 0.001). The wall thickness was nonhomogeneously distributed along the duodenal circumference, being thickest at high curvatures. In the future this may be useful for assessing the geometry, stiffness, remodeling, and mechanosensory properties in the duodenum and small intestine in health and disease.     

Impaired contractility and remodeling of the upper gastrointestinal tract in diabetes mellitus type-1

AIM To investigate that both the neuronal function of the contractile system and structural apparatus of the gastrointestinal tract are affected in patients with longstanding diabetes and auto mic neuropathy.METHODS The evoked esophageal and duodenal contractile activity to standardized bag distension was assessed using a specialized ultrasound-based probe. Twelve type-1 diabetic patients with autonomic neuropathy and severe gastrointestinal symptoms and 12 healthy controls were studied. The geometry and biomechanical parameters (strain, tension/stress, and stiffness) were assessed.RESULTS The diabetic patients had increased frequency of distension-induced contractions (6.0 ±0.6 vs 3.3 ± 0.5, P ＜ 0.001). This increased reactivity was correlated with the duration of the disease (P =0.009). Impaired coordination of the contractile activity in diabetic patients was demonstrated as imbalance between the time required to evoke the first contraction at the distension site and proximal to it (1.5 ± 0.6 vs 0.5± 0.1, P = 0.03). The esophageal wall and especially the mucosa-submucosa layer had increased thickness in the patients (P ＜ 0.001), and the longitudinal and radial compressive stretch was less in diabetics (P ＜0.001). The esophageal and duodenal wall stiffness and circumferential deformation induced by the distensions were not affected in the patients (all P ＞ 0.14).CONCLUSION The impaired contractile activity with an imbalance in the distension-induced contractions likely reflects neuronal abnormalities due to autonomic neuropathy. However, structural changes and remodeling of the gastrointestinal tract are also evident and may add to the neuronal changes. This may contribute to the pathophysiology of diabetic gut dysfunction and impact on future management of diabetic patients with gastrointestinal symptoms.     

The mechanics of left ventricular dysfunction in patients with Churg-Strauss syndrome

Background: Heart is frequently involved in Churg‐Strauss syndrome (CSS). However, the mechanics of left ventricular (LV) dysfunction in CSS has not been studied. Objective: To assess the mechanics of LV function and to characterize the contribution of longitudinal, circumferential and rotational deformation to LV dysfunction in CSS. Methods: We enrolled 22 CSS patients (eight males, mean age 43.2 ± 9.5 years) in remission of their disease and 22 sex‐ and age‐matched healthy subjects. All patients underwent conventional and two‐dimensional speckle‐tracking echocardiography. Global longitudinal, circumferential and rotational deformation parameters were calculated. Results: CSS subjects demonstrated lower LV ejection fraction (EF) than controls (56.6 ± 15.0% vs 63.8 ± 3.4%; P < 0.05). When compared to those with LVEF ≥ 50% (n = 14), CSS patients with LVEF < 50% (n = 7) had decreased global peak‐systolic longitudinal and circumferential strain/strain rate (all P < 0.001) and tended to have lower global peak‐systolic radial strain (P = 0.05). There were no differences between these two subgroups in global peak‐systolic radial strain rate and LV twist/torsion. When comparing individual systolic and diastolic parameters early diastolic longitudinal and circumferential strain rate demonstrated the highest correlation with corresponding global longitudinal and circumferential peak‐systolic strain/strain rate (r < ?0.80, P < 0.001 for all correlations). Conclusions: In CSS LV systolic dysfunction strongly correlates with longitudinal and circumferential, but not radial or rotational systolic components, indicating that impaired LV systolic function may result predominantly from impaired contraction of inner and middle, but not outer myocardial fiber layers. The spatial correspondence between systolic and diastolic deformation parameters suggests the similar impact of pathologic process on systolic and diastolic function in CSS. (Echocardiography 2012;29:568‐578)     

Thoracic spinal cord stimulation improves cardiac contractile function and myocardial oxygen consumption in a porcine model of ischemic heart failure

Thoracic Spinal Cord Stimulation . Background: Prior experimental studies show that thoracic spinal cord stimulation (SCS) improves left ventricular (LV) ejection fraction (LVEF). The mechanism of this improvement in the LV contractile function after SCS and its effects on the myocardial oxygen consumption remains unknown. Methods and Results: We performed thoracic SCS (T1‐T2 level) followed by 4 weeks of rapid ventricular pacing in 9 adult pigs with ischemic heart failure (HF) induced by myocardial infarction (MI). At 24 hours off‐pacing, detailed echocardiogram and invasive hemodynamic assessment were performed to determine LV contractile function and myocardial oxygen consumption. Serum norepinephrine level was measured before and after SCS. SCS was performed on 2 occasions for 15 minutes, 30 minutes apart (recovery) with 50 Hz frequency (pulse width 0.2 millisecond, 90% of motor threshold at 2 Hz output). Echocardiogram revealed significant decrease in LVEF (33.8 ± 1.8% vs 66.5 ± 1.7%, P < 0.01) after induction of MI and HF. Compared with MI and HF, acute SCS significantly increased LVEF and +dP/dt (all P < 0.05). Withdrawal of SCS during recovery decreased +dP/dt, but not LVEF that increased again with repeated SCS. Myocardial oxygen consumption also significantly decreased during SCS compared with MI and HF (P = 0.006) without any change in serum norepinephrine level (P = 0.9). Speckle tracking imaging showed significant improvement in global and regional circumferential strains over the infarcted mid and apical regions, decreased in time to peak circumferential strain over the lateral and posterior wall after SCS, and the degree of intraventricular dyssynchrony during SCS compared with MI and HF (P < 0.05). Conclusions: In a porcine model of ischemic HF, acute SCS improved global and regional LV contractile function and intraventricular dyssynchrony, and decreased myocardial oxygen consumption without elevation of norepinephrine level. (J Cardiovasc Electrophysiol, Vol. 23, pp. 534‐540, May 2012)     

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.     

Left ventricular torsion and strain in patients with repaired tetralogy of Fallot assessed by speckle tracking imaging

Background: In patients with tetralogy of Fallot (TOF), left ventricular (LV) dysfunction is an important factor associated with poor clinical outcome. Objective: The purpose of this study was to investigate the torsion and multidirectional strain of the LV in patients with TOF. Methods: Echocardiographic images were prospectively acquired in 29 patients who underwent TOF repair (age range, 5–25 years) and in 29 normal controls. Torsion and circumferential and longitudinal strain of the LV were assessed using speckle tracking imaging. Results: The torsion in patients was smaller compared to that in the controls due to small apical rotation and/or inverse basal rotation (P < 0.01). Torsion and untwisting rates decreased with increasing age (R = 0.37, P < 0.05). Basal circumferential strain and strain rate (SR) at systole and diastole decreased with age (R = 0.58; R = 0.57; R = 0.57, all P < 0.001) and were smaller in patients compared to those in the controls (all P < 0.01). Septal longitudinal strain and SR at systole and diastole decreased with age (R = 0.52; R = 0.62; R = 0.71, all P < 0.001) and were smaller than those of the controls (P < 0.01), although lateral longitudinal strain and SR were relatively maintained. Conclusion: Abnormal torsion and strain pattern of the LV were observed in patients without symptoms of cardiac failure. Assessment of torsion and strain is a very sensitive tool to detect the early deterioration of LV function in patients with TOF. (Echocardiography 2011;28:720‐729)     

Biomechanical and Histomorphometric Colon Remodelling in STZ-Induced Diabetic Rats

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.     

Viscoelastic Behavior of Small Intestine in Streptozotocin-Induced Diabetic Rats

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 tau1 and tau2 were computed. STZ-induced diabetes was associated with a progressive increase in the wall thickness and wall cross-sectional area (P < 0.05). tau1 and tau2 increased and C decreased. The slope alpha 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.     

Variability of migrating motor complex in humans

Fasting gastrointestinal motility in the human is characterized by the regular cycling activity of the migrating motor complex (MMC). Our purpose was to define the variability of the MMC within and between a group of six healthy subjects studied for 6–9 hr over six separate days with a perfused catheter system. A total of 88 phase III events was observed during 255 hr of recording in this group. The mean MMC cycling time varied significantly between subjects (range 113–230 min,P<0.001), and variation within subjects also was wide (sd range 58–70 min). Seventy-one percent of phase III events commenced in the gastric antrum, 18% in the proximal duodenum, 10% in the distal duodenum, and 1% in the proximal jejunum. For each subject, the velocity of propagation of phase III decreased significantly (P<0.001), and phase III duration increased significantly (P<0.001), with increasing distance from the os. In the antrum, phase I was predominant, and significant (P<0.006) variation between subjects was noted for percentage of MMC cycle occupied by phase I (overall mean ±sd 55±23%). Phase II was predominant in both duodenum and jejunum (mean range 70–80%), and no significant variation was noted between subjects for percentage of MMC occupied by phase II. We conclude that human MMC activity varies widely between individuals and within the same individual when studied on separate days.Presented, in part, at the American Gastroenterological Association meeting, Washington, D.C., May 1989, and published in abstract form in Gastroenterology (96:A127, 1989).