Collagen levels are normalized after decompression of experimentally obstructed colon

Collagen content in the vastus lateralis and the soleus muscle following a 90-day bed rest period with or without resistance exercises

INTRODUCTION

spaceflight seems associated with deterioration of the function of the skeletal muscles. Since muscle collagen is critical for muscle function, an improved understanding of the content of the muscle collagen during long-term inactivity seems important. Bed-rest with in-bed resistance training serves as a proxy for the conditions in space. Therefore, ground-based studies may improve the understanding of the consequences of long-term inactivity.

PURPOSE

the purpose is to compare the change in collagen protein in the vastus lateralis (VL) and the soleus (SOL) muscle amongst persons exposed to a 90-day bed rest with or without resistance exercise.

METHODS

an explorative analysis was completed based on data from a randomized, controlled trial. The intervention group (BRE, SOL n=4, VL n=8) performed supine-based squat exercises, whereas the controls (BE, SOL n=6, VL n=12) remained inactive during follow-up. Muscle biopsies from vastus lateralis and soleus were taken at baseline (pre) and after 90-days' follow-up (post). Muscle collagen (μg collagen/mg protein) was quantified. Two-way repeated measurements ANOVA was used to compare the interaction between the intervention (BRE/BR) and time (pre/post) for each muscle.

RESULTS

the collagen content of VL was similar between pre and post in the BRE group (-3.8 μg collagen/mg protein [95% CI: -22.0; 14.4], p=0.68) while it rose amongst individuals in the BR group (14.9 μg collagen/mg protein [95% CI: -0.01; 29.7], p=0.05). The difference of 18.66 [95% CI: -6.5; 43.9] between BRE and BR across time was, however, not significant (p=0.14). No significant reduction in SOL muscle collagen content was observed from pre to post in the BR group (-9.3 μg collagen/mg protein [95% CI: -24.9; 6.4], p=0.25) or in the BRE group (-6.5 μg collagen/mg protein [95% CI: -25.6; 12.6], p=0.50). There was no difference in the effect of BR versus BRE over time (mean difference -2.78 μg collagen/mg protein [95% CI: -29.7; 24.1], p=0.82).

CONCLUSION

muscle collagen content in the VL or SOL muscle does not seem to differ after a 90-day bed rest period with or without squat exercises.

GM6001 Increases Anastomotic Leakage following Colonic Obstruction Possibly by Impeding Epithelialization

BACKGROUND

Emergency operations performed on an obstructed colon are accompanied by an increased risk of anastomotic insufficiency. Tissue-destructive matrix metalloproteinase (MMP) activity is elevated in the obstructed colon and contributes to a loss of suture-holding submucosal collagen, which may be mediated by tumor necrosis factor (TNF)-α. Our aim was to study the effect of the non-selective MMP and TNF-α converting enzyme (TACE) inhibitor GM6001 (30 mg/kg) on anastomosis repair in obstructed left colon. GM6001 has been proved to be highly efficacious in elective anastomosis rodent models.

METHODS

A partial obstruction of the distal colon was induced in male Sprague-Dawley rats. After 4 d the obstructed colonic segment was resected, and an end-to-end anastomosis was constructed. Seven days later, the anastomoses were evaluated for clinical leakage. Histopathological and immunohistochemical assessments were also performed. Finally, the direct effect of GM6001 on epithelialization was studied in cultured colonic epithelial cells.

RESULTS

Unlike the robust beneficial effect on anastomosis under uncomplicated conditions, here GM6001 had a negative impact on anastomotic wound healing following colonic obstruction and substantially (p=0.004) more rats in the GM6001 group (75%) than in the control group (11%) had developed anastomotic leakage. In the anastomotic wounds, the myofibroblast abundance and cell proliferation were similar in the two groups. Histologically, GM6001 treatment resulted in wider and minimally epithelialized wounds that were commonly necrotic on the luminal side and infiltrated with numerous granulocytes. In vitro, GM6001 also delayed (p=0.026) epithelialization of denuded intestinal epithelium grown on type I collagen.

CONCLUSIONS

Non-selective MMP/TACE inhibition with GM6001 increased the anastomotic complications following colon obstruction. Inhibition of epithelialization is one possible mechanism responsible for the increased leakage following GM6001 treatment.

Fibrin glue does not improve healing of gastrointestinal anastomoses: a systematic review

BACKGROUND/AIM

Anastomotic leakage remains a frequent and serious complication in gastrointestinal surgery. In order to reduce its incidence, several clinical and experimental studies on anastomotic sealing have been performed. In a number of these studies, the sealing material has been fibrin glue (FG), and the results in individual studies have been varying. The positive effect of anastomotic sealing with FG might be due to the mechanical/physical properties, the increased healing of the anastomoses or both. The aim of this systematic review was to evaluate the existing evidence on the healing effects of FG on gastrointestinal anastomoses.

METHODS

PubMed, EMBASE and the Cochrane databases were searched for studies evaluating the healing process of gastrointestinal anastomoses after any kind of FG application. The search period was from 1953 to December 2013.

RESULTS

Twenty-eight studies were included in the qualitative synthesis. These studies were all experimental studies, since no human studies used histological or biochemical evaluation of healing. In 7 of the 28 studies, a positive effect of FG on healing was found, while 8 studies reported a negative effect and 11 studies found no effect. Furthermore, 2 studies reported unclear results. The difference in the study outcome was independent of the study design and the type of FG used.

CONCLUSION

In the available studies, FG did not consistently have a positive influence on the healing of gastrointestinal anastomoses. It is consequently plausible that the positive effect of FG sealing of gastrointestinal anastomoses, if there is any, may be due to a mechanical sealing effect rather than due to improved healing per se.

A novel animal model of gastrointestinal obstruction for the development of stent

BACKGROUND

The need for newer gastrointestinal (GI) stents has been continuously raised. Newly developed stents are generally tested for physical properties in vitro and directly introduced to clinical practice because there is no reliable animal model of GI obstruction. The aim of this study was to establish an animal model both that can represent obstruction of the GI tract and be used to develop new stents.

MATERIAL AND METHODS

Surgical obstruction of the descending colon by wrapping with a nonabsorbable synthetic mesh and rubber bands was made in 17 healthy mongrel dogs. Four days later, a covered self-expanding metallic stent was placed for the obstructed segment in each dog under fluoroscopic guidance. Patency and migration of the inserted stents were evaluated clinically on a daily basis and fluoroscopically on a weekly basis. After sacrifice of the dogs, the degree and extent of residual colonic obstruction were assessed fluoroscopically. The specimen of the colonic obstructed segment was examined microscopically.

RESULTS

In all 17 mongrel dogs, segmental obstruction in the descending colon was successfully created and confirmed with fluoroscopic examination using a contrast medium. The percentage of luminal narrowing ranged from 99%-100%. Stent placement was technically successful in all 17 dogs. During the follow-up period, stent migration occurred in 12 dogs and indwelling time of a stent ranged from 0-95 d (mean 29.2 ± 38.8 d). On postmortem pathologic examination, it was found that fibrosis had newly formed outside the colonic longitudinal muscle layer in all dogs.

CONCLUSIONS

Our canine colonic obstruction model is the first animal model that can be feasible for developing a new design of stent and provide in vivo data on complications, particularly stent migration.

Rapid morphological changes and loss of collagen following experimental acute colonic obstruction

PURPOSE

Anastomosis of an acutely obstructed colon is associated with an increased risk of dehiscence. In experimental models, acute obstruction decreases collagen in the colonic wall, but the time course and propagation along the colon of the biochemical changes are unknown. Furthermore, there is a paucity of information on the correlation between these biochemical changes and histological features.

METHODS

Forty male Sprague Dawley rats were subjected to partial obstruction by placing a silicone ring around the left colon 30 mm above the reflection. Obstruction was maintained for 0, 1, 2, 3 or 4 days. Samples from five different locations along the colon were analysed on circumference, tissue water content, collagen concentration and histomorphology. Neutrophil and macrophage infiltration was characterized immunohistochemically.

RESULTS

The colonic circumference and water content increased (p < 0.001), while the collagen concentration decreased by 48 % (p < 0.01) proximal to the obstruction already after 1 day. The degree of dilation and collagen reduction did not change significantly over the subsequent 3 days of obstruction, whereas the water content normalized by day 3. Mucosal and submucosal oedema and the relative neutrophil infiltration were highest after 1 day in the colonic segment proximal to the stenosis while the macrophage population continued to increase to day 4. Muscular necrosis in addition to ganglionitis and neuritis in the nervous plexus increased with duration of obstruction.

CONCLUSIONS

The pronounced and rapid changes of the composition of cells and the extracellular matrix of the colonic wall following acute obstruction may be of guidance for present surgical treatments and future pharmacological interventions.