Biomedical subjects

Jingbo Zhao

Publications and source records attributed to Jingbo Zhao.

27 records · Page 2Linked to original sources

PubMed2003

Morphological properties of zero-stress state in rat large intestine during systemic EGF treatment.

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.

Analysis of Variance↗

PubMed2003

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.

Animals↗

PubMed2003

Biomechanical properties of esophagus during systemic treatment with epidermal growth factor in rats.

The epidermal growth factor (EGF) is a growth factor with effects on many cell types and tissue. Morphometric and passive biomechanical properties were studied in isolated segments of the esophagus in 22 EGF-treated rats and 12 control rats. The rats were divided into groups with EGF treatment for 2, 4, 7, and 14 days (n=6 for each group except n=4 for the 14 days EGF-treatment group) or saline treatment (n=3 for each group). The mechanical test was performed as a distension experiment in vitro where the whole esophagus was stretched to its in situ length and distended with pressures up to 10 cm H2O using a ramp distension protocol. The pressure and outer diameter were recorded. Circumferential stress (force per area) and strain (deformation) were computed from the diameter and pressure data using the zero-stress state as reference. The zero-stress state was obtained by cutting esophageal rings radially. This caused the rings to open up into a sector. EGF induced pronounced morphometric changes, e.g., the wall thickness, wall cross-sectional area, and inner and outer circumferential lengths significantly increased during the EGF treatment. Histological analysis showed mucosa and submucosa growth during EGF treatment. The opening angle and residual strains increased with the highest value in the 14 days EGF-treated group (P<0.05). The change in opening angle depended largely on the change in mucosa thickness. Furthermore, the circumferential stiffness of the esophagus reached a maximum after 7 days EGF treatment (P<0.01).

Animals↗

PubMed2003

Morphology and stress-strain properties along the small intestine in the rat.

The stress-strain relationship is determined by the inherent mechanical properties of the intestinal wall, the geometric configurations, the loading conditions and the zero-stress state of the segment. The purpose of this project was to provide morphometric and biomechanical data for rat duodenum, jejunum and ileum. The circumferential strains were referenced to the zero-stress state. Large morphometric variations were found along the small intestine with an increase in the outer circumferential length and luminal area and a decrease in wall thickness in distal direction. The serosal residual strain was tensile and decreased in distal direction (P < 0.05). The mucosal residual strain was compressive and the absolute value decreased in distal direction (P < 0.001). The stress-strain experiments showed that the duodenum was stiffest. All segments were stiffest in longitudinal direction (P < 0.05). In conclusion, axial variation in morphometric and biomechanical properties was found in the small intestine. The zero-stress state must be considered in future biomechanical studies in the gastrointestinal tract.

Animals↗

PubMed2002

[The release amount and its change law of CO2 from soils in Xi'an area].

On the basis of the principle of which CO2 is absorbed by the solution of NaOH, the release amount of CO2 in soils under different vegetation was observed round the clock. The material shows that the release amount of CO2 from soils in Xi'an area changed clearly in 24 hours in months. The release amount changed from low to high and then to low from the morning to the next morning. The change of the release amount of CO2 was same that as the temperature, but the change of the former was about 4-6 hours later than that of the latter. The temperature was main factor determining change law of release amount of CO2 from soils and its rising and falling bring out the increase and decrease of release amount of CO2. The release amount of CO2 from soils was changing along with different vegetation. The forestry land was greater than grassland and the grassland was greater than the bare land in the release amount. The release amount was greater in day than in night.

Carbon Dioxide↗

PubMed2002

Morphometric and biomechanical intestinal remodeling induced by fasting in rats.

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

Biomechanical Phenomena↗

PubMed2002

Regional arterial stress-strain distributions referenced to the zero-stress state in the rat.

Morphometric and stress-strain properties were studied in isolated segments of the thoracic aorta, abdominal aorta, left common carotid artery, left femoral artery, and the left pulmonary artery in 16 male Wistar rats. The mechanical test was performed as a distension experiment where the proximal end of the arterial segment was connected via a tube to the container used for applying pressures to the segment and the distal end was left free. Outer wall dimensions were obtained from digitized images of the arterial segments at different pressures as well as at no-load and zero-stress states. The results showed that the morphometric data, such as inner and outer circumference, wall and lumen area, wall thickness, wall thickness-to-inner radius ratio, and normalized outer diameter, as a function of the applied pressures, differed between the five arteries (P < 0.01). The opening angle was largest in the pulmonary artery and smallest in thoracic aorta (P < 0.01). The absolute value of both the inner and outer residual strain and the residual strain gradient were largest in the femoral artery and smallest in the thoracic aorta (P < 0.01). In the circumferential and longitudinal direction, the arterial wall was stiffest in the femoral artery and in the thoracic aorta, respectively, and most compliant in the pulmonary artery. These results show that the morphometric and biomechanical properties referenced to the zero-stress state differed between the five arterial segments.

Animals↗

PubMed2002

The morphometry and biomechanical properties of the rat small intestine after systemic treatment with epidermal growth factor.

Morphometric and passive biomechanical properties were studied in isolated segments of the duodenum, jejunum and ileum in 22 EGF-treated rats and 12 control rats. The rats were allocated to groups with EGF treatment for 2, 4, 7, and 14 days (n = 6 for each EGF treatment group except n = 4 for the 14 days group) or saline treatment (n = 3 for each group). The intestinal segments were pressurized with Krebs solution from 0 to 8 cmH2O for duodenum and 0 to 6 cmH2O for jejunum and ileum using a ramp distension protocol. The diameter and length were recorded at different pressure levels. Circumferential and longitudinal stresses (force per area) and strains (deformation) were computed from the length, diameter, pressure and the zero-stress state data. EGF treatment was associated with pronounced morphometric changes, e.g., the wall thickness, wall area, and the circumferential lengths significantly increased during EGF treatment in all intestinal segments (P < 0.05). Histological analysis showed that the thickness and area of the layers increased after EGF treatment. With respect to the biomechanical data, the opening angle increased in all segments during EGF treatment with the highest value in the 14 days EGF treatment group (P < 0.05). The same result was found for residual strain and the residual strain gradient through the intestinal wall. Linear regression analysis demonstrated that the opening angle mainly depended on the mucosa thickness and area. Furthermore, the circumferential stiffness increased in the duodenum and decreased in the jejunum and ileum during EGF treatment. A plateau was reached after 7 days where after it started to normalize (P < 0.01). In the longitudinal direction, all intestinal segments became stiffer after EGF treatment for 7 days. After 14 days the curve started to normalize in duodenum and jejunum but not in the ileum.

Animals↗

PubMedDate not supplied

Biomechanical and histomorphometric esophageal remodeling in type 2 diabetic GK rats.

Diabetes mellitus induces remodeling of the morphology and mechanical properties in the gastrointestinal tract. This study aimed to investigate the histomorphometric and biomechanical remodeling of esophagus in the diabetic type 2 model Goto-Kakizaki (GK) rats. Five male diabetic GK rats and five male nondiabetic Wistar rats were used in this study. The mechanical test was performed in vitro where the whole esophagus was stretched to its in situ length and distended with pressures up to 10 cm H2O using a ramp distension protocol. The pressure and outer diameter were recorded. Circumferential stress (force per area) and strain (deformation) were computed from the diameter and pressure data using the zero-stress state as reference. The zero-stress state was obtained by cutting esophageal rings radially. This caused the rings to open up into a sector. The thickness, area, and the opening angle were measured from the digitized images. The layer circumference, thickness, and area were measured from histological slides. The collagen fraction was determined from histological slides with Van Gieson stain. Diabetes induced pronounced morphometric changes, e.g., the wall thickness and wall cross-sectional area significantly increased in the GK rats (P<.01). Histologically, the circumference, thickness, and area of the muscle layer and the collagen fraction of mucosa-submucosa layer were significantly increased in the GK rats (P<.01). The opening angle, outer residual strain, and residual strain difference to wall thickness ratio decreased significantly in the GK rats (P<.05 and P<.01). Furthermore, the circumferential stiffness of the esophagus is significantly higher in the GK rats than in the normal rats (P<.01). In conclusion, histomorphometric and biomechanical remodeling is a feature of the esophageal wall in GK rats.

Animals↗