M. Anurov

Surgical Mesh as a Scaffold for Tissue Regeneration in the Esophagus

Background: Textiles in the form of surgical meshes are widely used in hernia surgery. Their porous structure allows tissue infiltration to incorporate the fabric for complete healing and device stabilization. This study was aimed to reconstitute the esophageal wall and to investigate the functional and histological consequences of a new, non-absorbable polyvinylidene fluoride (PVDF) mesh and an absorbable polyglactin 910 (Vicryl®) mesh. Methods: Semicircular esophageal defects of 0.5 × 1 cm were created 2 cm proximal of the cardia in 10 rabbits. This gap was bridged using either polyglactin 910 or PVDF and additionally covered by omental wrapping. The clinical outcome was observed by clinical observation, regular esophagoscopies and X-ray contrast medium examinations. Local tissue regeneration was verified by light microscopy and immunohistochemistry. Results: After an observation period of 3 months we found no anastomotic strictures, complete mucosal regeneration, minimal inflammation reaction and initial regeneration of the muscle layer for the PVDF group. Within the polyglactin 910 group, three patch failures with consecutive anastomotic leakage occurred. Conclusion: The results indicate that PVDF mesh structure gives the opportunity of local tissue regeneration in the esophagus. Though re-epithelialization and muscle cell ingrowth could be detected for absorbable polyglactin 910 mesh, this implant was accompanied by a high and early rate of anastomotic leakage.

Modification of collagen formation using supplemented mesh materials

BackgroundFormation of recurrent inguinal and incisional hernia shows an underlying defect in the wound healing process. Even following mesh repair an altered collagen formation and insufficient mesh integration has been found as main reason for recurrences. Therefore the development of bioactive mesh materials to achieve a local modification of the scar formation to improve patients outcome is advisable.MethodsThirty-six male Wistar rats were used within this study. A Mersilene ® mesh sample was implanted after midline skin incision and subcutaneous preparation. Before implantation mesh samples were incubated for 30 minutes with either one of the following agents: doxycycline, TGF-beta 3, zinc-hydrogeneaspartate, ascorbic acid, hyaluronic acid. Incubation with a physiologic 0.9 % NaCl solution served as control. Seven and 90 days after mesh implantation 3 animals from each group (n = 6) were sacrificed for morphological observations. Collagen quantity and quality was analyzed measuring the collagen/protein as well as the collagen type I/III ratio.ResultsFollowing an implantation interval of 90 days supplementation with doxycycline (39.3 ± 7.0 µg/mg) and hyaluronic acid (34.4 ± 5.8 µg/mg) were found to have a significantly increased collagen/protein ratio compared to implantation of the pure Mersilene ® mesh samples (28.3 ± 1.9 µg/mg). Furthermore, an overall increase of the collagen type I/III ratio was found in all groups indicating scar maturation over time. However, no significant differences were found after 7 and 90 days of implantation comparing collagen type I/III ratio of supplemented mesh samples and control group.ConclusionsIn summary, we found an influence of supplemented mesh materials on collagen deposition. However, the investigated bioactive agents with reported influence on wound healing were not associated with an improved quality in scar formation.

Colon interposition for esophageal replacement: isoperistaltic or antiperistaltic? Experimental results

BACKGROUND Isoperistaltic colon is preferred to antiperistaltic colon for esophageal replacement, but experimental data do not exist to support this practice. METHODS In 7 dogs a 20 cm long colon loop was interposed between the skin and the small bowel, isoperistaltically in 3 dogs and antiperistaltically in 4 dogs. Three months later five strain-gauges were implanted and evacuation was investigated by motility testing, barium studies, and scintigraphy. RESULTS Motility recording showed normal colon motility in the excluded loops. Quiescent states (duration 40.2 +/- 13.6 minutes) were followed by contractile states (duration 7.5 +/- 2.4 minutes, frequency 3.3 +/- 0.6 per minute). The main peristaltic direction of isoperistaltic loops was isoperistaltic, and the main peristaltic direction of antiperistaltic loops was antiperistaltic. Evacuation took place exclusively during the contractile status. Half time emptying was more rapid in isoperistaltic loops (35 +/- 11 vs 69 +/- 16 minutes). The content of antiperistaltic loops was held back by antiperistaltic activity. Application of oatmeal porridge into the loops shortened the quiescent status from 40.2 to 13.2 +/- 4.8 minutes. CONCLUSIONS The colon graft for esophageal replacement is an active system. Food is stored during the quiescent states and evacuated during the contractile states. The original peristaltic direction is preserved so that retroperistalsis in antiperistaltic loops may lead to patient discomfort and pulmonary complications.

Large-Pore PDS Mesh Compared to Small-Pore PG Mesh

ABSTRACT Background: Currently, absorbable meshes are used as temporary closure in case of laparostoma. Unfortunately the multifilament polyglycolic acid (PG) meshes with small pores reveal little elasticity acting rather as a fluid barrier than permitting drainage of intra-abdominal fluids. Therefore, a new mesh was constructed of absorbable polydioxanon monofilaments (PDS) with increased porosity and longer degradation time. Material and Methods: For evaluation of the tissue response the new PDS mesh was implanted as abdominal wall replacement in each five rats for 7, 21, or 90 days, respectively, and compared to a PG mesh. Histological analysis included HE staining with measurement of the size of the granuloma and immunoshistochemistry for TUNEL, Ki67, TNF-R2, MMP-2, YB1, FVIII, gas6, AXL. Parameters for neovascularization and nerve ingrowth were analyzed. Results: The inflammatory and fibrotic tissue reaction is attenuated with PDS in comparison to PG, e.g., the size of the granuloma was smaller with less cell turnover, and less remodeling as represented by, e.g., reduction of apoptosis, expression of MMP-2, or TNF-R2. The number of ingrowing nerves and vessels explored via AXL, gas6, and factor VIII was increased in the PDS mesh. Conclusion: The results from the present investigation showed that a mesh can be constructed of monofilament PDS that induce significant less inflammatory and fibrotic reaction, however permits fluid drainage and preserves elasticity.

Phospholipids reduce adhesion formation in the rabbit uterine horn model

OBJECTIVE To access the ability of intraperitoneal phospholipids to reduce adhesions in a standardized model for gynecologic operations. DESIGN A randomized, experimental, blinded study using the double uterine horn model. SETTING Academic animal research laboratory. ANIMAL(S) Thirty-three Chinchilla rabbits. INTERVENTION(S) Phospholipids or Ringers lactate were intraperitoneally administered after bilateral uterine horn injury. MAIN OUTCOME MEASURE(S) After 10 days, adhesions were evaluated concerning area and strength as well as scores describing tenacity and degree. RESULT(S) Phospholipids (median 102.1 mm2) significantly reduce adhesion areas in comparison to surgical controls (median 392.2 mm2) and Ringer group (median 323.8 mm2). Scores reflecting severity and degree of adhesions support this finding. CONCLUSION(S) These results prove the efficacy of phospholipids in the double uterine horn model. Future clinical studies are recommended.

The influence of blood on the efficacy of intraperitoneally applied phospholipids for prevention of adhesions

BackgroundThe formation of adhesions following abdominal surgery is a well known problem. In previous studies we demonstrated the efficacy and safety of intraperitoneally applied phospholipids in order to prevent adhesion formation. This study evaluates the influence of blood on the efficacy of intraperitoneally applied phospholipids for prevention of adhesions.MethodsIn 40 Chinchilla rabbits adhesions were induced by median laparotomy, standardized abrasion of the visceral and parietal peritoneum in defined areas of the ventral abdominal wall and the caecum. The animals were randomly divided into four groups. They received either phospholipids 3.0% or normal saline (NaCl 0,9%) (5 ml/kg body weight). In 50% of the rabbits we simulated intraperitoneal bleeding by administration of blood (1,5 ml/kg body weight). The other half served as control group. Ten days following the operation the animals were sacrificed and adhesion formation was assessed by computer aided planimetry and histopathologic examination.ResultsThe median adhesion surface area in the NaCl-group (n = 9) amounted to 68,72 mm2, in the NaCl+Blood-group (n = 10) 147,68 mm2. In the Phospholipid (PhL)-group (n = 9) the median adhesion surface area measured 9,35 mm2, in the PhL+Blood-group (n = 9) 11,95 mm2. The phospholipid groups had a significantly smaller adhesion surface area (p < 0.05).ConclusionAgain these results confirm the efficacy of phospholipids in the prevention of adhesions in comparison to NaCl (p = 0,04). We also demonstrated the adhesion preventing effect of phospholipids in the presence of intraperitoneal blood.

Intestinale Motilität nach laparoskopischer vs. konventioneller Cholezystektomie

First descriptions of clinical courses after laparoscopic cholecystectomy indicate a shorter period of postoperative ileus in comparison to conventional cholecystectomy. Early postoperative motility was registered in dogs (n = 10) by implanted serosal electrodes. Furtheron clinical signs of postoperative motility were documented in patients (n = 100) after laparoscopic and conventional cholecystectomy. In animal experiments a significantly reduced period of postoperative ileus (5,5 ± 1 h) occured after laparoscopic cholecystectomy in comparison with the conventional technique (46 ± 5 h). Experimental data correlate well with earlier clinical signs of normal motility after laparoscopic cholecystectomy in patients. The shorter period of postoperative ileus is a further evidence for the minor abdominal trauma of laparoscopic techniques.SummaryFirst descriptions of clinical courses after laparoscopic cholecystectomy indicate a shorter period of postoperative ileus in comparison to conventional cholecystectomy. Early postoperative motility was registered in dogs (n = 10) by implanted serosal electrodes. Furtheron clinical signs of postoperative motility were documented in patients (n = 100) after laparoscopic and conventional cholecystectomy. In animal experiments a significantly reduced period of postoperative ileus (5,5 ± 1 h) occured after laparoscopic cholecystectomy in comparison with the conventional technique (46 ± 5 h). Experimental data correlate well with earlier clinical signs of normal motility after laparoscopic cholecystectomy in patients. The shorter period of postoperative ileus is a further evidence for the minor abdominal trauma of laparoscopic techniques.ZusammenfassungErste Beschreibungen klinischer Verläufe nach laparoskopischen Eingriffen lassen im Vergleich zur konventionellen Vorgehensweise eine verkürzte Periode der postoperativen Darmatonie vermuten. Die frühe postoperative Motilität wurde im Tierexperiment (Hund, n = 10) mittels implantierter Serosa-Elektroden verifiziert. Desweiteren wurden die klinischen Parameter der postoperativen Motilität nach laparoskopischer und konventioneller Cholezystektomie bei Patienten (n = 100) vergleichend erfa\t. Es zeigte sich eine signifikant verkürzte Periode der Darmatonie nach laparoskopischer Cholezystektomie (5,5 ± 1 h) im Vergleich zur konventionellen Technik (46 ± 5 h) im Tierexperiment. Dies korrelierte mit den deutlich früher einsetzenden klinischen Zeichen einer normalen Motilität bei Patienten nach einer laparoskopischen Cholezystektomie. Die kürzere Periode der postoperativen Darmatonie ist ein weiteres Indiz für das geringere Abdominaltrauma laparoskopischer Verfahren.

Comet-Tail-Like Inflammatory Infiltrate to Polymer Filaments Develops in Tension-Free Conditions

Background: Mesh reinforcement in hiatal hernia repair becomes more frequent but is charged by complications such as erosion or stenosis of the oesophagus. These complications are accompanied by an intense inflammatory infiltrate around the polymer fibres. To characterize this effect, the response to polypropylene fibres in the absence of tension was examined. Methods: In rats, polypropylene sutures (USP size 1, 3-0 and 7-0) were placed in the subcutis of the abdominal wall without knot or tension. On postoperative days 3, 7 and 21, specimens were excised. The expressions of c-myc, β-catenin, Notch3, COX-2, CD68 and Ki-67 were measured by immunohistochemistry. Results: In the absence of tension, sutures were surrounded by a foreign body granuloma with an inflammatory infiltrate not encircling the fibre but forming almost symmetric comet-tail-like infiltrates on opposite sides. The expression of c-myc, β-catenin, Notch3, COX-2, CD68 and Ki-67 was significantly reduced over time in the comet tail, but not in the granuloma. Conclusions: Even in tension-free conditions, surgical sutures cause a foreign body response with infiltrates of inflammatory cells. This reaction is shaped like a comet tail, and its extension depends on the diameter of the used fibre. Therefore, for reduction of perifilamental infiltrates, not only absence of tension is required, but also a small-sized fibre textile.

Electrophysiological and Mechanical Activity of the Upper Gastrointestinal Tract After Duodenoplasty or Segmental Resection of Benign Gastric Outlet Stenosis

In an animal experimental study we examined the postoperative recovery of the motility of the upper gastrointestinal tract after operative treatment of a benign gastric outlet obstruction. At 45 Days after induction, a duodenal stenosis was resected in six dogs, and resolved by Finneys duodenoplasty in another six dogs. Fourteen days after segmental resection, the gastric emptying was faster [half evacuation time (T1/2) for semisolid food = 44.4 ± 16.8 min] than following duodenoplasty [T1/2 = 56.8 ± 25.3). Here motor migrating complexes (MMCs) started in the antrum and could be traced down to the jejunum. After segmental resection we recognized MMC only distal to the anastomosis. The duration of the whole MMC cycle (69.0 ± 18.6 min) as well as of the single phases was significantly shorter in the resection group than after duodenoplasty (108.0 ± 15.1 min). At 28 days after operation the differences in the electromyographic findings were smaller (82.0 ± 15.1 min vs. 111.4 ± 11.2 min), but still significant. Obviously humoral transmitters and the extrinsic neural system lead to good propagation of the MMC across the anastomosis, even before the intramural pathways are reestablished. Concerning the fast recovery of the motility of the upper gastrointestinal tract, duodenoplasty is superior to segmental duodenal resection.

Artifizielle Drucksteigerung im subkutanen Abszeß mit Nachweis einer systemischen Allgemeinreaktion

Abscess is customarily thought of as a collection of a large number of microorganisms, inflammatory cells and necrotic debris separated from the surrounding tissue by a fibrous capsule. Modern work focussed attention on more physico-chemical parameters in abscess pathogenesis. Recent experiences from animal models underline the impact of abscess pressure and bio-physicochemical parameters in the “abscess compartement” for systemic spreading. Arteficial raising of abscess-pressure in pigs up to 80 mmHg was followed by increase of temperature and heartbeat rate and decrease of median arterial pressure. Elevated levels of TNFα, IL-1 and positive blood cultures support the theory of abscess pressure as a most important variable in abscess formation. We conclude that abscess pressure may play a pivotal role in systemic spreading of the primarily localized process.ZusammenfassungDer Abszeß wird üblicherweise als eine lokale Ansammlung von Entzündungszellen und liquifizierenden Gewebenekrosen in einem nicht präformierten Raum, der sich vom angrenzenden Gewebe durch eine Abszeßmembran pathomorphologisch abgrenzen läßt, beschrieben. Bei der Pathogenese der Abszedierung stehen in der Literatur v. a. ätiologische Gesichtspunkte im Vordergrund. Erst moderne Arbeiten haben die biophysikalischen Grundlagen der Abszeßpathologie erarbeitet. In einem tierexperimentellen Modell am Hausschwein konnte die besondere Rolle des Abszeßdrucks und anderer physikochemischer Parameter bei der systemischen Propagierung des zunächst lokal begrenzten Geschehens nachgewiesen werden. Durch eine artifizielle und initiale Anhebung des Abszeßdrucks auf 80 mmHg, der über einen Zeitraum von 6 h konstant gehalten wurde, konnte ein Temperaturanstieg auf über 38°C, ein Anstieg der Herzfrequenz sowie ein Abfall des mittleren arteriellen Drucks belegt werden. Der Anstieg von TNFα und IL-1 sowie der Nachweis positiver Blutkulturen unterstreichen die wichtige Rolle des Abszeßdrucks bei der Systemisierung der primär lokalen Infektion. Das traditionelle „Ubi pus ibi evacua“ gewinnt durch die vorliegende Untersuchung eine aktuelle, pathophysiologisch fundierte Bedeutung.