Mast cells facilitate local VEGF release as an early event in the pathogenesis of postoperative peritoneal adhesions

BACKGROUND: Peritoneal injury sustained at laparotomy may evoke local inflammatory responses that result in adhesion formation. Peritoneal mast cells are likely to initiate this process, whereas vascular permeability/endothelial growth factor (VEGF) may facilitate the degree to which subsequent adhesion formation occurs. METHODS: Mast cell deficient mice (WBB6F1-/-), along with their mast cell sufficient counterparts (WBB6F1+/+), underwent a standardized adhesion-inducing operation (AIS) with subsequent sacrifice and adhesion assessment 14 days later in a blinded fashion. Additional CD-1 and WBB6F1+/+, and WBB6F1-/- mice were killed 2, 6, 12, and 24 hours after operation for measurement of VEGF by ELISA in systemic serum and peritoneal lavage fluid. Two further groups of CD-1 mice underwent AIS and received either a single perioperative dose of anti-VEGF monoclonal antibody (10 mug/mouse) or a similar volume of IgG isotypic antibody and adhesion formation 2 weeks later was evaluated. RESULTS: WBB6F1-/- mice had less adhesions then did their WBB6F1+/+ counterparts (median [interquartile range] adhesion score 3[3-3] vs 1.5[1-2] respectively; P < .003). Local VEGF release peaked 6 hours after AIS in both WBB6F1+/+ and CD-1 mice whereas levels remained at baseline in WBB6F1-/- mice. CD-1 mice treated with a single dose of anti-VEGF therapy during operation had less adhesions than controls (2[1.25-2] vs 3[2.25-3], P = .0002). CONCLUSIONS: Mast cells and VEGF are central to the formation of postoperative intra-abdominal adhesions with mast cells being responsible, either directly or indirectly, for VEGF release into the peritoneal cavity after operation. In tandem with the recent clinical success of anti-VEGF monoclonal antibodies in oncologic practice, our observations suggest an intriguing avenue for research and development of anti-adhesion strategy.     

Enteric bacteria and their antigens may stimulate postoperative peritoneal adhesion formation

BACKGROUND: Intraabdominal sepsis causes exuberant inflammation, which results in dense adhesions. Translocation of enteric bacteria and/or their antigens after laparotomy may therefore also affect peritoneal healing by promoting local release of proinflammatory cytokines. Our hypothesis was that targeted counter therapy could be beneficial if such contamination was to augment postoperative adhesion formation. METHODS: Two endotoxin-hyposensitive mouse strains (C3H/HeJ and C57BL/10ScCr) and their syngeneic counterparts (C3H/HeN and C57BL10/ScSn, respectively) underwent reproducible adhesion-inducing operation (AIO) (n=10/group) with sacrifice and blinded adhesion grading 14 days later. In addition, CD-1 mice were gavaged with fluorescein isothiocyanate labeled-lipopolysaccharide (FITC-LPS) prior to either AIO or sham laparotomy and had both peritoneal macrophages and circulating monocytes assessed by flow cytometry afterward. The cytokine-release response of resident peritoneal cells to LPS stimulation was assessed in vitro (murine peritoneal mast cell cultures) and in vivo (unoperated CD-1 mice administered LPS intraperitoneally [10 & 50 microg/mouse]). Finally, CD-1 mice (n=10/group) had AIO and received either bactericidal/permeability increasing protein (rBPI, 2 mg/mouse) or vehicle solution in the early postoperative period with assessment of adhesion formation 2 weeks later. RESULTS: Both HeJ and ScCr mice had less adhesions than their controls (P=.0015 and .0001, respectively, Mann Whitney U test). FITC-LPS uptake by peritoneal macrophages was striking after AIO. Intraperitoneal LPS provoked significant local vascular endothelial growth factor (VEGF) release as did the process of AIO. In vitro, LPS induced significant interleukin-(IL)-6 release from isolated mast cells. Intraperitoneal administration of rBPI to CD-1 mice early after AIO markedly attenuated subsequent adhesion formation (P=.0003). CONCLUSIONS: Peritoneal adhesion formation is exacerbated by peritoneal contamination due to translocation after laparotomy and may be attenuated by therapeutic antagonism.     

Fibrin gel limits intra-abdominal adhesion formation.

Autologous fibrin gel (FG) has recently been reported efficacious in hepatic injury; the effects of fibrin compounds on intra-abdominal adhesion formation is controversial. This study evaluated intra-abdominal adhesion formation in a rabbit devascularization model. Seventeen New Zealand rabbits were anesthetized and laparotomy was done. The uterine horns were abraded to punctate bleeding followed by bilateral uterine devascularization. Treatment consisted of 10 cc saline control (c) or FG applied to the uterine horns. Peritoneal lavage was done at 15 minutes for red blood cell (RBC) analysis. Autopsy was performed at 1 week. Adhesions were graded from grade 0 (no adhesions) to grade III (dense adhesions). Adhesion grading revealed no difference in average adhesion grade between FG and C with small bowel (1.0 +/- 1.3 vs 0.5 +/- 1.0); bladder (2.1 +/- 1.1 vs 2.4 +/- 1.2); or uterus (1.2 +/- vs 2.0 +/- 1.2). Adhesion grade was significantly less in FG compared to C for the colon and the abdominal incision (0.4 +/- 0.5 vs 1.7 +/- 1.1 and 1.2 +/- 1.1 vs 3.0 +/- 1.2; P less than 0.05 by t-test). There were no differences in lavage RBC count between FG and C (13.1 x 106 +/- 4.1 x 10(6) vs 8.7 x 106 +/- 3.2 x 10(6)). Fibrin gel significantly decreased incisional and colonic adhesions and reduced other abdominal adhesion formation by a nonhemostatic dependent mechanism.     

Association between the expression of mast cell chymase and intraperitoneal adhesion formation in mice

BACKGROUND: Adhesion formation is a major source of postoperative morbidity and mortality. Mast cells and their major protease, chymase, have been shown to participate in the healing process as well as in tissue remodeling. We aimed to identify the role of mast cells in intraperitoneal adhesion formation and to assess whether there is an association between the expression of mast cell chymase and adhesion formation. MATERIALS AND METHODS: Both mast cell-deficient W/W(V) mice and congenic +/+ mice received a standardized lesion produced by cecal scraping and the application of 95% ethanol. Adhesions were assessed blindly 1 week later using a standardized scale. In addition, histamine content, mast cell numbers, and chymase activity in cecum as well as at the healing sites were evaluated before and 7 days after surgical injury. RESULTS: A significant reduction in adhesion formation was seen in mast cell-deficient W/W(V) mice (P < 0.05). In the normal cecum, histamine content did not significantly differ between W/W(V) and +/+ mice. Chymase activity in cecum was detected in control +/+ mice, but not in W/W(V) mice. Mast cell numbers and chymase activity levels at the healing sites of +/+ mice were significantly increased 7 days after surgery. CONCLUSIONS: Our results indicate that mast cells contribute to intraperitoneal adhesion formation in mice, and suggest that chymase originating from mast cells is important in the development of adhesions.     

Development of peritoneal adhesions in macrophage depleted mice

BACKGROUND: We present a new mouse model for the study of peritoneal adhesions using macrophage Fas-induced apoptosis (Mafia) transgenic mice expressing a Fas-FKBP construct under control of the murine c-fms promoter. Mafia mice allow systemic macrophage depletion by dimerization of Fas with a synthetic dimerizer, AP20187. Results demonstrate that macrophage depletion in Mafia mice induces peritoneal adhesion formation when the peritoneal cavity is also exposed to an irritant. The Mafia mouse model presents a reproducible, non-surgical approach for research in adhesion formation and prevention. MATERIALS AND METHODS: Mafia mice were treated with AP20187 using an intravenous (i.v.) or intraperitoneal (i.p.) injection. Control groups included mock-treated Mafia mice and both AP20187 and mock-treated wild type mice. Seven days after treatment, mice were observed for the presence of adhesions. RESULTS: After i.p. injection with AP20187, 76% of Mafia mice developed adhesions whereas none of the mock-treated Mafia or wild-type mice developed adhesions, and only one AP20187-treated wild-type mouse (5.8%) developed a mild adhesion. Mafia mice treated with AP20187 i.v. exhibited macrophage depletion not significantly different than i.p. treated mice, but did not develop adhesions. In contrast, Mafia mice treated with AP20187 i.v. developed adhesions when diluent was also injected into the peritoneal cavity, whereas i.p diluent alone had no effect. CONCLUSION: Macrophage depletion, combined with a peritoneal irritant, results in peritoneal adhesion formation in transgenic Mafia mice. Macrophages appear to play a protective role in the development and/or repair of peritoneal adhesions.     

Role of fibrinolysis in the formation of postoperative adhesions

It has been hypothesized that peritoneal hypofibrinolysis is of importance in the formation of postoperative adhesions, but results from experiments with fibrinolytic modulators are conflicting. We tested this hypothesis in a controlled prospective study in rabbits, comparing the effects of fibrinolytic inhibition (tranexamic acid) to fibrinolysis enhancement by local instillation of gel containing tissue-type plasminogen activator. Adhesion formation was measured after 1 week in a strictly standardized way and is presented as a percentage of an induced lesion that was covered by adhesions. Fibrinolytic inhibition significantly increased adhesion formation, both to the parietal peritoneum (34.2%+/- 3.2%) compared with untreated control (19.7%+/- 3.3%, p < 0.01) and to the bowel (76.3%+/- 5.8%) compared with untreated control (51.2%+/- 8.7%, p < 0.05). Control gel significantly increased adhesions to the parietal peritoneum (35.6%+/- 4.6%) versus untreated control (19.7%+/- 3.3%, p < 0.05), whereas gel containing tissue-type plasminogen activator significantly reduced the amount of adhesions to the parietal peritoneum (4.9%+/- 1.7%) compared with untreated control (19.7%+/- 3.3%, p < 0.01) and abolished adhesion formation to the injured bowel. The fibrinolytic system thus seems to be intimately involved in the early formation of intraabdominal adhesions.     

Ⅰ型神经纤维瘤病基因型小鼠的破骨细胞功能研究

目的 观察Ⅰ型神经纤维瘤病基因型小鼠的破骨细胞功能变化,探讨Ⅰ型神经纤维瘤病引起骨质疏松的发病机制.方法 选取神经纤维瘤病基因杂合型(Nfl+/-)和野生型(Nfl+/+)小鼠为研究对象,取胫骨干骺端行抗酒石酸酸性磷酸酶(TRAP)染色,比较两组小鼠骨内破骨细胞含量.体外实验取两种基因型小鼠的骨髓单核细胞,观察在巨噬细胞集落刺激因子(M-CSF)和细胞核因子KB受体活化因子配基(RANKL)诱导下的破骨细胞分化能力,测定两组破骨细胞形成、分化、贴附、迁移和骨吸收功能.结果 Nfl+/一小鼠骨内成熟破骨细胞数量比Nn+/+增多,细胞体积明显增大(TRAP阳性区面积占总面积的百分比分别为Nfl+/+,(0.8800±0.0014)%;Nfl+/-,(2.3300±0.0013)%,P<0.01),差异有统计学意义;体外培养的Nn+/-破骨细胞形成增多,(每1×105骨髓单核细胞形成的破骨细胞数分别为Nfl+/+,41.75±13.14:N仃+/-,61.17±18.17,P<0.01)差异有统计学意义;体外诱导培养的破骨细胞的黏附、迁移、骨吸收功能强(黏附细胞数量Nn+/+,53.00±11.08;Nil+/-,108.00±11.67,JP<0.01;迁移细胞数量Nn+/+,88.33±12.40;Nn+/-,239.83±67.77,P<0.01骨吸收面积百分比Nfl+/+.18.37%±0.0367;Nfl+/-,(40.4400±0.1052)%,P<0.01).两者差异有统计学意义.结论 破骨细胞增多,功能增强是Ⅰ型神经纤维瘤病引起骨质疏松的发病机制之一.     

Fibrin glue reduces intra-abdominal adhesions to synthetic mesh in a rat ventral hernia model

Postoperative intra-abdominal adhesions are associated with significant morbidity and mortality. In this study, the effect of topical fibrin glue (FG) on adhesion formation in a rat model was investigated. Forty Sprague-Dawley male rats underwent midline laparotomy. Bilateral peritoneal-muscular abdominal wall defects were created and then replaced with premeasured soft tissue Goretex patches. Rats were randomized to FG sprayed over the patches or to a control group. Two observers blinded to the randomization assessed the severity of adhesions to the patch by scoring the density of adhesions (grades 0-3) and the percentage of the patch area covered by adhesions (0-100%). The mean percentage of the patch covered by adhesions was 32.8 +/- 6.1 per cent for the FG group versus 57.9 +/- 6.7 per cent for the control group (P < 0.01). The mean density of adhesions for the FG group was 0.95 (+/-0.17) versus 2.0 (+/-0.21) for the control group (P = 0.001). Topical FG reduces the severity and density of intra-abdominal adhesions in a rat model.     

Attenuation of adhesion formation after cardiac surgery with a chymase inhibitor in a hamster model

OBJECTIVE: Chymase is one of the inflammatory mediators and is released from mast cells, which are closely associated with adhesion formation. Chymase also activates transforming growth factor beta1, which promotes tissue fibrosis. However, the role of chymase in cardiac adhesion formation has not yet been elucidated. We have assessed whether a specific chymase inhibitor, Suc-Val-Pro-Phe(p) (OPh)(2), prevents postoperative cardiac adhesions in hamsters. METHODS: In 66 hamsters the epicardium was abraded, and then either chymase inhibitor or placebo was injected into the left thoracic cavity, leaving the pericardium open. Cardiac chymase activity, the level of transforming growth factor beta1 in the pleural fluid, and the density of epicardial mast cells were measured 3 days postoperatively. The degree of adhesion formation was evaluated macroscopically and histologically 2 weeks postoperatively by using a grading score ranging from 0 (no adhesions) to 4 (severe adhesions). RESULTS: The cardiac chymase activity and level of transforming growth factor beta1 were lower in the chymase inhibitor-treated group compared with in the placebo-treated group (45.8 +/- 18.7 vs 79.7 +/- 13.7 microU/mg protein [P <.025] and 15.6 +/- 6.5 vs 33.2 +/- 9.8 microg/mL [P <.01], respectively). The density of mast cells was higher in the placebo-treated group, and there was suppression to 60% of this value in the chymase inhibitor-treated group. The adhesion scores were lower in the chymase inhibitor-treated group compared with in the placebo-treated group (1.3 +/- 1.3 vs 3.0 +/- 1.1, P <.01). CONCLUSION: Use of a chymase inhibitor suppresses not only cardiac chymase activity but also the level of transforming growth factor beta1, and this results in a reduction in postoperative cardiac adhesion.     

An autopsy study of the peritoneal cavity from patients on continuous ambulatory peritoneal dialysis

Sixteen autopsies were performed on patients aged 56 +/- 15 (SD) years who were on continuous ambulatory peritoneal dialysis (CAPD) for 834 +/- 766 (SD) days. Lactate-buffered dialysate and povidone-iodine antiseptic were used in all cases. Multiple peritoneal sections were taken to evaluate peritoneal membrane thickening, inflammation, neovascularization, fibrosis, and adhesions. Peritoneal thickening, inflammation, or adhesions were not related to sex, race, or etiology of renal failure. Time on dialysis was also not a direct determinant of peritoneal adhesions or neovascularization. Peritonitis episodes correlated with chronic peritoneal serosal changes. This study supports the hypothesis that peritoneal alterations in patients on CAPD are related to episodes of peritonitis.     

免疫与炎症调节在腹腔粘连形成中的作用

腹腔粘连是临床常见的手术并发症,临床与实验研究证实：各种抗粘连药物和材料以及微创设备的应用并不能有效预防术后粘连的形成。为减少与控制粘连的发生,自世界第一台外科手术诞生以来,国内外学者从不同角度对腹腔粘连的发病机制进行研究,积累了大量文献。而免疫与炎症在腹腔粘连病理生理过程影响研究逐渐受到重视,笔者对国外学者进行的相关研究文献进行系统分析,旨在了解腹腔粘连炎症与免疫之间的关系,为临床防治提供新的靶标与路径。     

Attenuating effects of chymase inhibitor on pericardial adhesion following cardiac surgery

OBJECTIVE: Chymase, a serine protease, is released from mast cells, which is closely associated with adhesion formation. Chymase activates transforming growth factor-beta1 (TGF-beta1), which promotes tissue fibrosis. Recently we have found that chymase may play an important role in adhesion formation in hamsters. Accordingly, this study was designed to confirm that a chymase inhibitor prevents postoperative cardiac adhesions in large animals. METHODS: In 14 dogs, the epicardium was abraded 200 times with gauze and the mid-portion of the left anterior descending coronary artery (LAD) was exposed with No. 15 blade. Either chymase inhibitor (CI group, n = 7) or placebo (P group, n = 7) was sprayed into the pericardial cavity, then the pericardium was closed. Cardiac chymase activity, the level of TGF-beta1 in the pericardial fluid, the density of epicardial mast cells, the adhesion area between the heart and the pericardium, and the presence of adhesion between the mid-LAD and the pericardium were evaluated 1 and 2 months after surgery. Five nonsurgical dogs were used as a control for cardiac chymase activity. RESULTS: Cardiac chymase activity and TGF-beta1 level were lower in CI group than in P group (53.7 +/- 35.0 vs. 93.4 +/- 20.4 microU/mg protein, p = 0.01, 3.2 +/- 0.9 vs. 4.3 +/- 1.1 microg/mL, p = 0.06, respectively). In CI group, the density of mast cells (19 +/- 5 vs. 32 +/- 8 cells/cm, p < 0.01), the adhesion area (2.2 +/- 0.8 vs. 7.5 +/- 1.5 cm2, p < 0.01), and adhesions between the heart and the mid-LAD (0% vs. 57%) were all reduced. CONCLUSION: Chymase inhibitor suppresses cardiac chymase activity and reduces the TGF-beta1 level, resulting in a reduction of cardiac adhesion in a large animal.     

Effects of overexpression of human GLUT4 gene on maternal diabetes and fetal growth in spontaneous gestational diabetic C57BLKS/J Lepr(db/+) mice.

During gestation, heterozygous C57BLKS/J-Lepr(db/+) mice develop spontaneous gestational diabetes mellitus (GDM), and the newborn fetuses are macrosomic compared with offspring from wild-type (+/+) mothers. To investigate the effects of the leptin receptor mutation on maternal metabolism and fetal growth during pregnancy, we studied +/+, db/+, and db/+ transgenic mice that overexpress the human GLUT4 gene two- to three-fold (db/+TG6). During pregnancy, fasting plasma glucose and hepatic glucose production were twofold greater in db/+ than +/+ mice, despite similar insulin levels. In skeletal muscle, insulin-stimulated tyrosine phosphorylation was decreased in pregnant +/+ mice, and even more so in db/+ mice: insulin receptor beta (IR-beta), +/+ 34%, db/+ 57% decrease, P<0.05; insulin receptor substrate 1 (IRS-1), +/+ 44%, db/+ 61% decrease, P<0.05; and phosphoinositol (PI) 3-kinase (p85alpha), +/+ 33%, db/+ 65% decrease, P<0.05. Overexpression of GLUT4 in db/+TG6 mice markedly improved glucose-stimulated insulin secretion, by 250%, and increased IRbeta, IRS-1, and p85alpha phosphorylation twofold, despite no change in concentration of these proteins. Plasma leptin concentration increased 40-fold during pregnancy, from 2.2+/-0.5 to 92+/-11 ng/ml and 3.6+/-0.1 to 178+/-34 ng/ml in +/+ and db/+ mice, respectively (P<0.01), but was increased to only 23+/-3 ng/ml in pregnant db/+TG6 mice (P<0.001). Maternal fat mass and energy intake were greater in db/+ mice, and fat mass was reduced by GLUT4 overexpression, independent of food intake. Fetal body weight was increased by 8.1 and 7.9% in db/+ and db/+TG6 mothers, respectively (P<0.05), regardless of fetal genotype, whereas fetuses from db/+TG8 mothers (four- to fivefold overexpression) weighed significantly less compared with pups from +/+ or db/+ mothers (P<0.05). These results suggest that the single mutant db allele effects susceptibility to GDM through abnormalities in insulin receptor signaling, defective insulin secretion, and greater nutrient availability. GLUT4 overexpression markedly improves insulin-signaling in GDM, resulting in increased insulin secretion and improved glycemic control. However, maternal hyperglycemia appears not to be the sole cause of fetal macrosomia. These data suggest that GDM is associated with defects in insulin receptor signaling in maternal skeletal muscle, and this may be an important factor provoking maternal and fetal perinatal complications.     

Pentoxifylline Increases Antiadhesion Effect of Streptokinase on Postoperative Adhesion Formation: Involvement of Fibrinolytic Pathway

Pentoxifylline reduces peritoneal adhesions and increases peritoneal fibrinolysis in rodents. Furthermore, the activation of the fibrinolytic system by streptokinase leading to degradation of fibrin is effective in the prevention of adhesion formation. We have investigated the effects of pentoxifylline and streptokinase alone and/or coadministration on postoperative intra-abdominal adhesion formation in adult female NMRI mice. Drugs were administered from the day of surgery until 10 days after surgery. At relaparotomy 11 days after surgery, the abdomen was opened, and the adhesions were graded in a blinded fashion utilizing the classification system described. Oral gavage administration of lower doses of pentoxifylline (3.125, 6.25, and 12.5 mg/kg) had no significant effect on postsurgical adhesion formation, while the higher doses of pentoxifylline (25 and 50 mg/kg) significantly decreased postsurgical adhesion formation. Moreover, intraperitoneal injection of lower doses of streptokinase (9.375, 18.75, and 37.5 unit/kg, i.p.) had no significant effect on postsurgical adhesion formation, while the higher doses of streptokinase (75 and 150 unit/kg) significantly decreased postsurgical adhesion formation. In other series of experiments, coadministration of lower doses of pentoxifylline and streptokinase doses, which were ineffective when given alone, significantly decreased postsurgical intra-abdominal adhesion formation compared with streptokinase control group. The results suggest that pentoxifylline may interfere with streptokinase in the reduction of postoperative intra-abdominal adhesion formation by enhancing local fibrinolytic activity.     

Transient receptor potential vanilloid subfamily 1 is essential for the generation of noxious bladder input and bladder overactivity in cystitis

PURPOSE: We evaluated the role of transient receptor potential vanilloid subfamily 1 for the generation of noxious bladder input and bladder overactivity associated with cystitis. MATERIALS AND METHODS: Spinal c-fos expression triggered by innocuous bladder distention (10 cm water) was studied in sham and lipopolysaccharide inflamed transient receptor potential vanilloid subfamily 1 +/+ and -/- mice. Bladder reflex activity was studied using urethane anesthesia in sham and lipopolysaccharide inflamed transient receptor potential vanilloid subfamily 1 +/+ and -/- mice. RESULTS: Inflammatory changes in the bladder of transient receptor potential vanilloid subfamily 1 +/+ and -/- mice were identical. Bladder distention in sham inflamed +/+ mice induced a mean +/- SD of 4 +/- 2 Fos cells per section. Bladder distention after lipopolysaccharide inflammation increased Fos cells to 34 +/- 5 (p <0.001). The number of Fos cells after bladder distention in sham and lipopolysaccharide inflamed -/- mice was similar (2 +/- 1 and 2 +/- 1, respectively, p >0.05). During saline infusion of sham inflamed bladders in +/+ mice 0.46 +/- 0.14 contractions per minute were documented. In lipopolysaccharide inflamed +/+ mice that frequency was increased to 1.13 +/- 0.12 contractions per minute (p <0.001). In sham and lipopolysaccharide inflamed -/- mice bladder frequency was similar (0.47 +/- 0.08 and 0.61 +/- 0.10, respectively, p >0.05). CONCLUSIONS: Our data demonstrate that transient receptor potential vanilloid subfamily 1 is essential for the generation of noxious bladder input and bladder overactivity associated with cystitis.     

Compound heterozygous loss of Ext1 and Ext2 is sufficient for formation of multiple exostoses in mouse ribs and long bones

Multiple Hereditary Exostoses (MHE) syndrome is caused by haploinsufficiency in Golgi-associated heparan sulfate polymerases EXT1 or EXT2 and is characterized by formation of exostoses next to growing long bones and other skeletal elements. Recent mouse studies have indicated that formation of stereotypic exostoses requires a complete loss of Ext expression, suggesting that a similar local loss of EXT function may underlie exostosis formation in patients. To further test this possibility and gain greater insights into pathogenic mechanisms, we created heterozygous Ext1(+/-) and compound Ext1(+/-)/Ext2(+/-) mice. Like Ext2(+/-) mice described previously (Stickens et al. Development 132:5055), Ext1(+/-) mice displayed rib-associated exostosis-like outgrowths only. However, compound heterozygous mice had nearly twice as many outgrowths and, more importantly, displayed stereotypic growth plate-like exostoses along their long bones. Ext1(+/-)Ext2(+/-) exostoses contained very low levels of immuno-detectable heparan sulfate, and Ext1(+/-)Ext2(+/-) chondrocytes, endothelial cells and fibroblasts in vitro produced shortened heparan sulfate chains compared to controls and responded less vigorously to exogenous factors such as FGF-18. We also found that rib outgrowths formed in Ext1(f/+)Col2Cre and Ext1(f/+)Dermo1Cre mice, suggesting that ectopic skeletal tissue can be induced by conditional Ext ablation in local chondrogenic and/or perichondrial cells. The study indicates that formation of stereotypic exostoses requires a significant, but not complete, loss of Ext expression and that exostosis incidence and phenotype are intimately sensitive to, and inversely related to, Ext expression. The data also indicate that the nature and organization of ectopic tissue may be influenced by site-specific anatomical cues and mechanisms.     

The effect of vitamin E on experimentally induced peritoneal adhesions in mice

Previous studies in our laboratory demonstrated that dietary supplementation with vitamin A enhances peritoneal adhesion formation in mice. Other researchers have shown that vitamin E antagonizes some effects of vitamin A in various systems, eg, wound healing. We investigated our hypothesis that dietary supplementation with vitamin E would decrease peritoneal adhesion formation. Adult mice were divided into the following groups: group 1, which ate a standard chow containing 65 IU of vitamin E per kilogram diet (twice the National Research Council's recommended daily allowance for normal mice); and group 2, which ate the same chow supplemented with vitamin E at 300 IU/kg diet (a nontoxic level). Following peritoneal ligation, all mice were killed on the tenth postoperative day and their peritoneal cavities examined for the presence and extent of adhesions. There was a statistically significant decrease in the incidence and degree of adhesions in the vitamin E-supplemented animals; these data supported our hypothesis.     

Collagen-PVP,a collagen synthesis modulator,decreases intraperitoneal adhesions

BACKGROUND: Adhesion formation in the peritoneal cavity is the most common cause of intestinal obstruction and secondary female infertility. A great effort has been dedicated to reduce adhesion formation because of the associated morbidity and its complications. MATERIALS AND METHODS: This study was designed as a before-after comparative trial and included 14 rabbits, with a weight between 300 and 500 g. All rabbits were appendectomized and 1 month later laparotomized to assess adhesion formation. Rabbits were randomized into two groups, Group I (control group), with no intervention, and Group II (experimental group), treated with an intraperitoneal sponge of collagen-polyvinylpyrrolidone (Clg-PVP). The laparotomy procedure was repeated 1 month later for a new assessment of adhesion formation and histological evaluation by H-E and Masson staining. RESULTS: Histological findings showed abundant infiltrate in the control group, which was mild in the experimental group. With the Masson stain the control group showed a significantly higher amount of collagen than the experimental group and the fibrous tissue was more compact. We found a mean number of adhesions of 3.29 +/- 1.98 for the control group, which decreased to 2.57 +/- 0.79 after the second laparotomy. For the experimental group the mean number of adhesions decreased from 1.86 +/- 0.90 to 0.71 +/- 0.49 after the second laparotomy, with no statistical difference between both groups before Clg-PVP application, but a significant statistical difference after the implantation of Clg-PVP (Student's t test; P < 0.001, two-tailed). CONCLUSION: Collagen-polyvinylpyrrolidone decreases the incidence and size of intraabdominal adhesions after secondary adhesion formation after appendectomy.     

Prevention of postoperative adhesions with the chitin derivative N-O-carboxymethylchitosan

The ideal barrier agent for the prevention of surgical adhesions has remained elusive. We have examined the ability of a new hydrogel N-O-carboxymethylchitosan, a derivative of chitin with properties similar to the extracellular matrix, to prevent adhesions when applied topically to traumatized mesothelial surfaces. In two rodent adhesion models (pericardial and peritoneal), the application of N-O-carboxymethylchitosan significantly prevented or minimized the formation of scar and fibrosis. According to a scoring system from 0 to 3 (0 = no adhesions and 3 = severe dense adhesions), control groups in each model consistently produced severe dense adhesions (2.9 +/- 0.2, 2.7 +/- 0.3). All treated groups consistently scored less than 1.0, indicating minimal or no fibrosis. The differences between the control and treated groups were statistically significant (p < 0.05). Thus, the application of N-O-carboxymethylchitosan to traumatized mesothelial surfaces may have significant potential in the prevention of postoperative adhesion formation.