Biomedical subjects

B Klosterhalfen

Publications and source records attributed to B Klosterhalfen.

116 records · Page 7Linked to original sources

PubMed1988

[The surgical anatomy of the rectal and anal blood vessels].

The authors examined 40 rectum specimens by angiography, preparation and staining methods to show the exact arterial vessel supply of the rectum and tried to find out whether a reason could be found for the relatively high rate of suture leaks after low resection of the rectum or not. The insertion of the levator muscle is a sort of vessel divide: caudal to the levator muscle the inferior rectal artery is the main supplying vessel, cranially the superior rectal artery. Here a vessel deficient-area always remains in the dorso-caudal sector of the rectal ampulla which cannot be compensated by another rectum-supplying vessel. The middle rectal artery supplies the rectum accessorily. The results are able to explain why the suture leaks are constantly observed in the dorso-caudal ampulla after profound anterior resection of the rectum. Furthermore the results account for the good healing tendency of coloanal anastomoses: the inferior rectal artery amply supplies the anal canal; there is not the same vessel-deficient area as found cranial to the levator muscle.

Anal Canal↗

PubMedDate not supplied

Determination of stent stenosis: an in vivo experimental comparison of intravascular ultrasound and angiography with histology.

PURPOSE: To compare intravascular ultrasound (IVUS) and angiography with histology in determining the degree of stent stenosis in an in vivo experiment. METHODS: In 16 sheep, a total of 64 stents were implanted into the external iliac arteries. Two stents were inserted on either side. Patency was followed by angiography and IVUS. Four types of stent were used: two Dacron-covered (Cragg Endopro and heparinized Cragg Endopro) and two noncovered (Cragg and Memotherm stents). Eight animals were killed after 1 month, eight others after 6 months. Histological sections were prepared from the stented vessels. Measurements of the patent and total stent diameters determined by IVUS, angiography, and histology were compared. RESULTS: Correlation between IVUS and angiography was 0.75, between IVUS and histology 0.77, and between angiography and histology 0.85. A mean stent stenosis of 17 +/- 11% (range 0-51%) was found on angiography, of 10 +/- 11% (0-46%) on IVUS, and of 20 +/- 11% (4%-49%) on histology. In comparison with histology, IVUS underestimated the degree of stenosis by 10 +/- 8%, and angiography underestimated it by 3 +/- 6%. Resolution of IVUS was calculated to be about 0.35 mm and that of angiography to be about 0.15 mm. CONCLUSION: Under experimental conditions, IVUS was not superior to angiography in determining the degree of stent stenosis in long-segment stenoses of iliac artery stents, when measurements were correlated with histology. Angiography is sufficient for following the patency of iliac artery stents.

Angiography↗

PubMedDate not supplied

Collagen I/III and matrix metalloproteinases (MMP) 1 and 13 in the fascia of patients with incisional hernias.

The late appearance ofincisional hernias several years after laparotomy and the high recurrence rates after operation strongly imply the presence of a disorder of the connective tissue, although a specific defect in patients with incisional hernias has not yet been identified. In the present study we used both immunohistochemistry and Western blot analysis to evaluate the ratio of collagen I and III and the expression of the metalloproteinases (MMP) 1 and 13 in the fascia of patients with incisional or recurrent incisional hernias. Samples of healthy skin or stable skin scar in patients without hernias served as controls. Altogether, our data indicated a significantly decreased ratio of collagen I/III in the fascia of patients with incisional hernias and recurrent incisional hernias. Furthermore, in these patients the expression of MMP-1 was decreased compared to the controls, whereas MMP-13 could not be detected in any fascia sample, with or without hernias present. For the first time, our results give evidence of the existence of a possible collagen disorder in these patients. The decreased ratio ofcollagen I/III is explainable due to a relative increase of collagen type III, which is known to be characterized by thin fibril diameters and lowered mechanical strength. The altered collagen ratio might be the result of the decreased activity of MMP-1, whereas the absent MMP-13 expression did not seem to modify the scar formation. Thus, our data indicate the presence of collagen metabolic disorders in patients with incisional hernias and recurrent incisional hernias. Furthermore, these results might explain the poor results of a mesh-free hernia repair, which again builds up scar tissue of inadequate collagen composition and strength.

Adult↗

PubMedDate not supplied

Influence of mesh materials on collagen deposition in a rat model.

Alterations of the extracellular matrix (ECM) with its major component collagen are increasingly discussed as possible risk factors implicated in the development of abdominal-wall herniation. Because of the widespread use of alloplastic meshes for the surgical repair of hernias, an animal study was performed to analyze the influence of various mesh materials on the quantity and quality of collagen deposition. In 60 male Sprague-Dawley rats an abdominal replacement was performed using three different kinds of mesh materials: polyester (PE), a pure polypropylene (PP), and a composite mesh made of polypropylene and polyglactin (PG). A simple fascia suture repair served as control. The count of fibroblasts, the collagen/protein ratio, the type I/III collagen ratio, and the expression of basic fibroblast growth factor (b-FGF) at the interface were analyzed after 7, 21, and 90 days. The ratio of collagen to overall protein (microg/mg) showed significant differences comparing different mesh materials (sham controls 38.44 +/- 16.33 microg/mg, PE 68.5 +/- 23.8 microg/mg, PP 101.6 +/- 32.3 microg/mg, PG 49.6 +/- 11.6 microg/mg at day 90). The ratio of collagen type I/III increased over time in all groups. However, 90 days after mesh implantation the ratio was always significantly lowered compared to the controls. No significant difference was found comparing different mesh materials. The alteration of the scar composition is closely connected to an increased b-FGF expression. b-FGF and count of fibroblasts highly correlated (r =.95) and showed significant elevated levels compared to simple suture repair. The results of our study strongly support the notion that wound healing is affected by mesh implantation. The quality of the ECM deposition as determined by collagen type I/III ratio is impaired in general, whereas the quantity of ECM deposition is markedly influenced by the kind of mesh material.

Animals↗

PubMedDate not supplied

CT and MRI of experimentally induced mesenteric ischemia in a porcine model.

OBJECTIVE: Our goal was to assess the value of CT and MRI for the detection of bowel wall changes in experimentally induced mesenteric ischemia. METHODS: in 18 female pigs, a percutaneous embolization of the superior mesenteric artery was performed with buthyl-2-cyanoacrylate and Lipiodol (1:1) (experimental group). In six animals, only diagnostic imaging and histologic evaluation were performed (control group). CT was carried out 3, 6, and 12 h after occlusion. Incremental CT (1 s scan time, 5 mm slice thickness, 7 mm increment, 120 kV/290 mAs) and spiral CT (slice thickness 5 mm, pitch 1.5, 120 kV/165 mA) were performed pre and post contrast injection (Somatom Plus/Siemens). Serial CT was carried out after intravenous contrast injection (1 ml/kg, 2 ml/s). MRI (Magnetom 1.5 T; Siemens) was performed with T1 (pre and post 0.01 mmol/kg Gd-DTPA; Magnevist; Schering, Germany), T2, and proton density images in axial orientation. Slice thickness was 3 mm and slice gap 1 mm. Additionally, a T1-weighted GE sequence (multislice FLASH 2D) was obtained in dynamic technique (before and 30, 60, and 90 s after contrast agent injection) with a slice thickness of 5 mm. Biometrical monitoring included blood pressure, heart frequency, blood cell count, electrolyte status, blood gas analysis, and determination of serum lactate. Image evaluation included morphological analysis and determination of the enhancement pattern. Histological specimens were obtained and analyzed according to the Chiu classification. RESULTS: The histologic workup of the specimen 3, 6, and 12 h after vascular occlusion revealed an average Chiu state 3, 4, and 5. On CT, the bowel wall had a thickness of 4.7 mm on average in the ischemic segments. There was a significant difference from the control group (average 3 mm). Free intraperitoneal fluid and intramural gas were seen after 12 h of ischemia in 80%. In ischemic bowel segments, no mural enhancement was seen. Normal segments and the bowel of the control animals showed an enhancement of 34 HU on average (SD = 3.1 HU; p.<0.01). In MRI, S/N and C/N differed significantly between experimental and control groups in T1 and proton density images. In ischemic segments of all phases, the bowel wall did not show contrast enhancement. Healthy segments and bowel of control animals showed a significant enhancement (p<0.01). CONCLUSION: Cross-sectional imaging has a high sensitivity for delineation of ischemic bowel wall segments. The enhancement pattern of the bowel wall enables detection of location, extent, and cause of a acute arterial mesenteric ischemia with high accuracy in an early phase.

Animals↗

PubMedDate not supplied

Mesh implants in hernia repair. Inflammatory cell response in a rat model.

BACKGROUND: In the reinforcement of the abdominal wall with mesh implants, various complications including hernia recurrence, abdominal pain, seroma formation and infection are discussed to depend on the biocompatibility of the alloplastic prosthesis. Particularly macrophages, T-cells and mast cells have been shown to play a major role in the inflammatory response to biomaterials. To approach biocompatibility of surgical meshes we therefore examined the infiltrate of these cells as well as the proliferation rate in response to different clinically applied materials. MATERIALS AND METHODS: Three mesh materials (polypropylene: PP, Prolene; polyethylene terephthalate: PET, Mersilene, and polypropylene/polyglactin: PP + PG, Vypro) were compared after inlay implantation in a standardized rodent animal model. A suture-closed laparotomy served as control. After 7 and 90 days of implantation, histochemical analysis of the inflammatory response to all biomaterials was performed: macrophages (ED3), T-cells (CD3), proliferating cells (PCNA) and mast cells (Giemsa) were investigated. RESULTS: In all groups a persisting T-cell response was observed. Colonization of the interface with macrophages showed a pronounced reduction in the PP + PG-mesh group. Infiltration of mast cells at the tissue graft interface showed a time-dependent decrease in the PET- and PP + PG-mesh groups, whereas in contrast, index of mast cells increased in the PP-mesh group. At both time points, indices of proliferation were highest in the PP-mesh group. CONCLUSION: The present data confirm the development of a biomaterial-dependent chronic inflammatory response to surgical meshes with macrophages as the predominant cell type. Further research on the recruitment of inflammatory cells and in particular on the role of mast cells and their granular products should be encouraged.

Animals↗

PubMedDate not supplied

Vypro II mesh in hernia repair: impact of polyglactin on long-term incorporation in rats.

BACKGROUND: To the Vypro II mesh, a large-pore-sized multifilamentous polypropylene mesh for hernia repair, supplementary polyglactin 910 multifilaments were added to improve intraoperative handling. As it has been suggested that polyglactin induces fibroplastic reactions and wound complications, this study was designed to evaluate the long-term tissue reaction to polyglactin in the Vypro II mesh. MATERIALS AND METHODS: Two mesh materials, the Vypro II composite mesh (PP + PG) and the pure polypropylene variant (PP), were compared after inlay implantation in a standardized rodent animal model. After 14, 28, 42, 56, 84 and 112 days of implantation, histological analysis of the inflammatory response was performed: material absorption, inflammatory tissue reaction, fibrosis and granuloma formation were investigated. RESULTS: Total absorption of polyglactin filaments of the Vypro II mesh occurred between 56 and 84 days of implantation. Both the inflammatory and the fibrotic reaction were initially increased in the PP + PG mesh group. These differences disappeared in the following implantation period. After 112 days, inflammation was even less pronounced in the PP + PG mesh group. CONCLUSION: The present data confirm a short-term polyglactin-induced increase in inflammation and fibrosis around implanted Vypro II meshes in rats. With regard to the long-term tissue response, even an anti-inflammatory property of polyglactin multifilaments in low-weight and large-pored polypropylene meshes cannot be ruled out.

Absorption↗

PubMedDate not supplied

Persistent extracellular matrix remodelling at the interface to polymers used for hernia repair.

On the one hand, recurrence rates and postoperative complications following hernia repair are supposed to be influenced by the kind of mesh material used. On the other hand, an impaired collagen metabolism and cleavage within connective tissue has been suggested as decisive factor in the pathogenesis of recurrent hernia formation. The aim of our study was, therefore, to analyze the impact of commonly used mesh materials on quality of collagen deposition, expression of collagenases (matrix metalloproteinases; MMP-1/MMP-13), and specific tissue inhibitors of MMPs (TIMPs) in an animal study. Four different mesh materials were used (Prolene = polypropylene, Mersilene = polyester, and Vypro and Vypro II = combinations of polypropylene and polyglactin) and implanted as abdominal wall replacement in 60 male Wistar rats. Mesh samples were explanted after 3, 21, and 90 days and investigated using immunohistochemistry (expression of MMP-1/MMP-13 and TIMP-1) and cross-polarization microscopy (percentage of collagen type III to overall collagen). Besides an insufficient collagen composition with an increased percentage of collagen type III, we found a complex expression of collagenases and their inhibitors combined with a persistent chronic foreign-body reaction even 90 days after implantation. Except for TIMP-1 expression, which was significantly related to a lowered amount of inflammatory (r = -0.980, p = 0.02) and connective tissue formation (r = -0.951, p = 0.049), there was no relation to the expression of collagenases (MMP-1/MMP-13) with regard to the amount of inflammatory and connective tissue formation despite partly significant differences between implanted polymers.

Animals↗