Efficacy of photodynamic therapy in the treatment of venous trophic ulcers: results from the experiment

Introduction. Today, antimicrobial photodynamic therapy (a-PDT) becomes more and more popular, because of it pronounced bactericidal activity, anti-inflammatory effect. At the same time, no animal model studies have been conducted on morphological changes in cells after exposure to PDT on venous ulcers (VU) when using different types of photosensitizers (PS). The problem of comparing morphological changes in tissues when using a-PDT vs conventional PDT have not yet been resolved.

Aim. Evaluation of the effectiveness of PDT and APDT in a comprehensive examination of trophic ulcers in an in vivo experiment and compare them with standard methods for the treatment of VLU.

Materials and мethods. A series of experiments was conducted on 21 rabbits, separated into 3 equal groups of 7 rabbits each. Venous trophic ulcer was originally modeled for all rabbits. To obtain a VU, we performed an additional ligation of v. femoralis. The control group received standard therapy for VU. The PDT group had PDT with Photosens. The a-PDT group underwent a-PDT using Cholosens. Every 3 days, picture of local inflammation, regeneration rate and ulcer volume were determined. A morphological study of VLU was carried out on the first, 9th and 15th days.

Results. The a-PDT group, day 15: 100% wound epithelization. Control group, day 21st: The volume of wounds decreased on average by 50%. The PDT group: 100% wound epithelization. The morphological study indicated a positive trend in the a-PDT group compared with PDT and control groups, which resulted in a decrease in the total mass of necrotic detritus, a change in the quantitative and qualitative composition of inflammatory infiltrate.

Conclusion. The data obtained indicate that the use of a-PDT is recommended in treatment of VLU. Both PDT and a-PDT methods showed better results in comparison with standard therapy.

Comparative Study of Sutureless Fixation of Lightweight Surgical Meshes for Hernia Repair in a Rat Model

The aim of this study was to compare the efficacy of different methods of sutureless fixation of lightweight meshes made of different polymers for repair of experimental hernias. Two lateral hernia defects were modeled in male rats and covered with polyester and polypropylene prostheses. The meshes were fixed with Histacryl glue (group 1), or self-gripping meshes were used (group 2), or the meshes were implanted without fixation (group 3). On day 5 after surgery, mesh position and efficiency of fixation were evaluated. It was found that fixation is necessary for all light surgical meshes. Polyester meshes demonstrated better adhesive properties than polypropylene meshes. The most pronounced differences in the adhesive properties were found for self-gripping prosthesis, while in the groups with glue fixation, the differences were less pronounced.

Comparison of the results of hernia defect plasty with standard and light surgical meshes with identical knitted structure

Standard and light surgical meshes with identical knitted structure: Parietene Standard/Parietene Light and Premilene/Optilene were chosen for hernioplasty in 20 rats. Six months after surgery, the complications were primarily related to inflammation in groups with implanted standard meshes and with prosthesis deformation in groups with light meshes. The character of complications was determined by characteristics of knitting structure and mechanical proprieties of surgical meshes.

Biomechanical compatibility of surgical mesh and fascia being reinforced: dependence of experimental hernia defect repair results on anisotropic surgical mesh positioning

PURPOSE

We aimed to compare the effectiveness of experimental middle hernia defect repair in regard to the transverse and longitudinal positioning of anisotropic lightweight surgical mesh.

METHODS

The mechanical properties of fascial layers and surgical mesh DynaMesh(®)-PP Light were determined in two perpendicular directions under uniaxial tension. In 12 male Wistar rats, middle hernia defect was repaired by the sublay technique. In six animals, the mesh was positioned across (DLH group) and in the other six along (DLV group) the midline. At 6 months after implantation, mesh deformation, structural rearrangement, and repaired abdominal wall biomechanics were evaluated. Histological sections were stained with van Giesen and Mallory's trichrome.

RESULTS

The anisotropic mechanical properties of the mesh and fascial layers coincided in the DLH group, but did not correspond to each other in the DLV group. In the DLV group, meshes were stretched in width by 11.4% and reduced in length by 12.7%. In all animals, the lower edge of the mesh was shifted to a defect area with margin hernia formation in two rats. Constant shear stress caused disproportional connective tissue formation. Repaired abdominal wall lost its natural elasticity. In the DLH group, the mesh deformation was minimal. Formed connective tissue was tightly associated with the anterior layer and did not differ from it in composition. The mechanical properties of repaired abdominal wall were close to those of the anterior layer.

CONCLUSIONS

In prosthetic hernia repair, the mechanical properties of surgical mesh should correspond with those of the fascia being repaired. A mismatch of mechanical properties may result in implant deformation, abdominal wall biomechanics impairment, and recurrent herniation at the edges of the meshes.

Impact of position of light mesh endoprosthesis with anisotropic structure for the efficiency of anterior abdominal wall reconstruction

Mechanical testing of light mesh endoprosthesis Ultrapro for stretching and bending resistance showed strong anisotropy of the material along and across the loop columns. Ultrapro endoprosthesis was placed parallel and perpendicularly to the midline during plastic repair of a hernial defect in rats. Six months after surgery, the development of hernias and violation of endoprosthesis structure were observed in the group with longitudinal orientation of the endoprosthesis. Transverse orientation of the endoprosthesis led to fortification of the defect site. However, the meshes were in some cases misshapen and formed folds across the loop columns, because of insufficient bending rigidity and elasticity of the material.

Experimental study of the impact of the textile structure of mesh endoprostheses for the efficiency of reconstruction of the anterior abdominal wall

Endoprostheses made from knitted fabric of 3 loop types were used for hernioplasty in rats. Biocompatibility of implanted textile constructions was evaluated after 6 months. The intensity of inflammatory reaction and types of complications in animals depended on the loop type and method of finishing of the mesh endoprosthesis tissue.

Intraabdominal adhesion formation of polypropylene mesh Influence of coverage of omentum and polyglactin

BACKGROUND

Adhesions after intraabdominal surgical procedures are related to high morbidity and mortality. Biomaterials, particularly those made of polypropylene, in the intraabdominal position have to be considered as pathophysiological cofactor in a multifactorial process of adhesion formation. To investigate the adhesive potential induced by the biomaterial, an animal model was performed. In addition, the influence of coverage by omentum or a polyglactin barrier was investigated.

METHODS

In, 18 Chinchilla rabbits the biomaterial was placed laparoscopically using the intraperitoneal onlay mesh technique. Using this model, a polypropylene-polyglactin mesh compound (PPMC) was used with three different implantation techniques: group 1, PPMC implantation without coverage (PPMC): group 2, PPMC implantation with additional omentum coverage (PPMC-O): and group 3, PPMC implantation with coverage of an absorbable polyglactin mesh (PPMC-V). The degree of adhesion formation was measured 90 days after implantation by computer-assisted planimetry. Morphometric examination followed the explantation analyzing the amount of foreign body response.

RESULTS

We found a significant reduction of adhesion formation for the PPMC and PPMC-O groups compared to the PPMC-V group, in which dense adhesions were found. Morphometric investigations of the perifilamental granulomas of the pure (PPMC) group revealed a typical foreign body reaction with a mild to moderate fibrosis around all mesh fibers. However, tissue specimens of the PPMC-O and PPMC-V groups indicated a similar inflammatory reaction but significantly increased connective tissue formation around the polymer fibers compared to the pure PPMC group.

CONCLUSION

The intraabdominal placement of a pure PPMC shows a neoperitonealization and perifilamental collagenous ingrowth with almost no adhesions. Coverage with omentum (PPMC-O) or polyglactin mesh (PPMC-V) resulted in a significant increase in inflammation and perifilamentary connective tissue formation.

Experimental evaluation of phospholipids and icodextrin in re-formation of peritoneal adhesions

Background

The formation of further adhesions after adhesiolysis is a major problem. Not all agents that are supposed to reduce de novo adhesions can reduce further adhesion formation. The efficacy and safety of intraperitoneally applied phospholipids has been shown previously. This study evaluated the influence of phospholipids and icodextrin on adhesion re-formation.

Methods

In an experimental study on 60 Chinchilla rabbits adhesions were induced by standardized abrasion of defined areas of the ventral abdominal wall, the caecum and the ileum. Open adhesiolysis was performed 10 days later. The animals randomly received either 1·5 per cent phospholipids, 4 per cent icodextrin or Ringer's lactate intraperitoneally. Half of the animals in each group were killed after a further 10 days and the remainder at 20 days. Adhesion formation was assessed by computer-aided planimetry and histopathological examination.

Results

Phospholipids (10 days: P = 0·001; 20 days: P = 0·012) and icodextrin (10 days: P = 0·006; 20 days: P = 0·055) reduced adhesion re-formation after both intervals compared with Ringer's lactate controls.

Conclusion

Phospholipids and icodextrin were effective in preventing re-formation of adhesions.

Effects of intra-abdominal drainages on adhesion formation and prevention by phospholipids in a rat model. Drainages and adhesion formation

BACKGROUND AND AIMS

The study was designed to asses the adhesiogenic capacity of silicone drainages and the protective effect of phospholipids (PL).

MATERIALS AND METHODS

A total of 75 Wistar rats were randomly assigned to the different groups. In a preliminary trial (pt; n = 15), all rats underwent midline laparotomy. The control group (C(pt); n = 5) received no further treatment. In the other animals, either an 'easy flow' drainage (EF(pt); n = 5) or an 'Aachen' drainage (AC(pt); n = 5) was placed into the abdominal cavity. In the final study (fs; n = 60), rats underwent laparotomy and colonic anastomosis. The control groups (C(fs)) received no drainages. In the other groups either one of the two types of drainages (EF(fs), AC(fs)) were introduced. In 50% of the rats, 75 mg/kg of PL were administered intraperitoneally (C(fs)+PL, EF(fs)+PL, AC(fs)+PL). The other rats received no additional treatment (C(fs)ØPL, EF(fs)ØPL, AC(fs)ØPL). All animals were sacrificed 10 days after surgery. Areas of adhesions and anastomotic bursting pressures were measured (mean +/- SD).

RESULTS

In the preliminary trial, analysis of variance (ANOVA) revealed no differences between the groups after application of drainages (values are given in mean +/- SD): C(pt) mean 23.3 +/- 29.4 mm(2), EF(pt) 829.7 +/- 679.3 mm(2), AC(pt) 609.9 +/- 219.4 mm(2). In the final study, 2-factorial ANOVA showed a significant effect (p < 0.001) for the use of drainages but not for the application of PL (C(fs)ØPL 140.6 +/- 124.2 mm(2), C(fs)+PL 67.7 +/- 60.4 mm(2), EF(fs)ØPL 1,217.0 +/- 458.3 mm(2), EF(fs)+PL 1,266.8 +/- 368.3 mm(2), AC(fs)ØPL 861.7 +/- 274.8 mm(2), AC(fs)+PL 544.2 +/- 193.8 mm(2)). Post hoc test for pairwise comparisons adjusted to Bonferroni showed significant differences (p < 0.001) between all of the three pairs (C(fs) 104.1 +/- 92.3 mm(2) vs. EF(fs) 1,241.9 mm(2) +/- 413.3 mm(2); C(fs) vs. AC(fs) 702.9 mm +/- 234.3 mm(2); EF(fs) vs. AC(fs)).

DISCUSSION

The final study demonstrates the adhesiogenic capacity of silicone drainage tubes in combination with anastomoses. Any protective effect of PL alone or in combination with drainages could not be shown.

CONCLUSIONS

Indication for the use of drainages in standard surgical procedures should be reconsidered within the scope of their potential to cause adhesions and subsequent complications.

Influence of intraperitoneal phospholipid dosage on adhesion formation and wound healing at different intervals after surgery

BACKGROUND

Adjuvant therapy is needed to prevent adhesion formation as a major cause of postoperative morbidity and mortality. The efficacy of phospholipids (PLs) has been proven; however, information on dosage and drug safety are still outstanding.

MATERIALS AND METHODS

Forty-eight Chinchilla rabbits underwent median laparotomy, abrasion of the peritoneum, jejunal anastomosis, and an electrocautery incision of the liver. The operation was completed by intraperitoneal administration of PLs in two different concentrations (30 mg/kg and 70 mg/kg body weight). In the control group, the abdomen was closed without additional treatment. Adhesion area, anastomotic bursting pressure, tensile strength of the midline incision, and healing of the liver wound were assessed on days 3, 5, 7, and 10, respectively.

RESULTS

The mean areas of adhesions in the control group were slightly larger than in the PL groups after 3 days and 5 days. On day 7 and day 10, both PL groups presented with significantly smaller adhesion areas (P<0.05). In all groups, we measured equal anastomotic bursting pressures on the 3rd, 5th, and 10th postoperative days. After 7 days, the mean value of the PL 70-mg group (17.2 kPa) was significantly lower than in the other groups (control 22.1 kPa, PL 30 mg 20.7 kPa; P<0.05). The tensile strengths of the laparotomy wound measured after intervals of 5 days and 7 days were not statistically different. On day 3, it was reduced after 30 mg PL but enhanced after 70 mg PL, whereas 10 days after surgery the strength increased with the PL dosage. The inflammatory reparative response to hepatic injury, jejunal anastomosis, and midline incision was not affected by PLs as assessed by histological analysis.

CONCLUSION

These results prove the efficacy of PLs in adhesion prevention in two concentrations. The findings reveal an unimpeded healing of anastomoses, laparotomy wounds, and liver incisions at different periods after surgery.

Efficacy of adhesion prevention and impact on wound healing of intraperitoneal phospholipids

BACKGROUND

Postoperative peritoneal adhesions are a major complication of abdominal surgery. Adjuvant therapy is needed to prevent adhesion formation and subsequent sequelae. Previously published data proved the efficacy of phospholipids (PL) for this indication; however, additional information on drug safety was still outstanding. The underlying study was designed to investigate the influence of phospholipids on three different types of healing tissue.

MATERIALS AND METHODS

A total of 48 Chinchilla rabbits underwent median laparotomy, standardized abrasion of the visceral and parietal peritoneum, jejunal anastomosis, and an electrocautery incision of the liver. The operation was completed by intraperitoneal administration of 10 ml/kg of either normal saline (NaCl) or phospholipids (12%).

RESULTS

After 5 (NaCl 691 mm(2) vs PL 192 mm(2)) and 10 days (NaCl 625 mm(2) vs PL 88 mm(2)) the control group presented with significantly larger adhesion areas (P < 0.05). The bursting pressure of the anastomosis on the 5th (NaCl 16.1 kPa vs PL 18.2 kPa) and 10th (NaCl 19.7 kPa vs PL 18.6 kPa) postoperative days showed no statistically significant difference. The tensile strength of the laparotomy wound measured after intervals of 5 (NaCl 8.5 N cm(-1) vs PL 6.8 N cm(-1)) and 10 days (NaCl 23.0 N cm(-1) vs PL 20.2 N cm(-1)) was not statistically different either. The collagen protein ratio of anastomoses, laparotomy wounds, and liver incisions as well as the inflammatory-reparative response of the different tissues was not affected by PL.

CONCLUSIONS

These results confirm the efficacy of phospholipids in adhesion prevention. The findings of uncompromised healing of anastomoses, laparotomy wounds, and liver incisions demonstrate the safety of this agent. Further data may qualify phospholipids for a clinical trial.