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Biomedical subjects

T Schmitz-Rixen

Publications and source records attributed to T Schmitz-Rixen.

At least 19 recordsLinked to original sources
PubMed2006

Increased endothelial cell apoptosis in symptomatic high-grade carotid artery stenosis: preliminary data.

OBJECTIVE: Endothelial cell (EC) apoptosis has been associated with thrombus formation on an eroded atherosclerotic plaque surface. Alongside plaque rupture, it may constitute another mechanism of plaque destabilisation. We investigated whether EC apoptosis also may be involved in plaque destabilisation in high-grade internal carotid artery (ICA) stenosis. METHODS: We compared the degree of EC apoptosis in carotid endarterectomy specimens from n=38 patients undergoing surgery for high-grade ICA stenosis (> or =70%; n=19 clinically asymptomatic; n=19 symptomatic). The total number of endothelial cells (ECs) and apoptotic cells were determined using CD31 immunohistochemistry and the TdT dUTP nick end-labeling (TUNEL) method respectively. RESULTS: Overall, EC apoptosis was a rare finding. The median percentage of apoptotic ECs was 0.0% (0.0-0.7%) in asymptomatic and 0.5% (0.0-7.3%) in symptomatic plaques (p=0.015, Mann-Whitney U test). No difference was observed between ruptured and unruptured plaque (0.0% [0.0-6.0%] vs 0.0% [0.0-5.7%]; p=0.446). CONCLUSIONS: Our results indicate that TUNEL-detected EC apoptosis is rare in carotid plaque from patients with >70% stenosis.

Aged↗
PubMed2005

Fibrous cap thickness and smooth muscle cell apoptosis in high-grade carotid artery stenosis.

OBJECTIVE: There is growing evidence that, in high-grade internal carotid artery (ICA) stenosis, continuous fibrous cap thinning is not mandatory for plaque rupture and symptom development. The possibility that smooth muscle cell (SMC) apoptosis is involved in loss of fibrous cap volume has only been examined in a limited number of patients with high grade carotid artery stenosis. METHODS: Endarterectomy specimens from n = 38 consecutive patients undergoing surgery for high-grade ICA stenosis (> or = 70%) were transversely sectioned at 2 mm intervals. Plaque instability was defined clinically, by a history of recent ischemic symptoms (< 60 days before surgery; n = 19) attributable to the stenosis, or histopathologically by the presence of plaque rupture (n = 14). Detailed morphometric analyses of the fibrous cap was based on routine stains; for DNA in situ end labeling the TUNEL technique was used. SMCs were identified by immunostaining for SMC actin. RESULTS: We found no significant difference between symptomatic/asymptomatic or ruptured/unruptured plaque with respect to various morphometric measures of the fibrous cap (i.e. mean area, number of plaque sections with fibrous cap, necrotic core-to-lumen distance at its thinnest or thickest part). The mean (+/- SD) apoptotic SMCs per thousand within the fibrous cap was significantly higher in symptomatic vs. asymptomatic (64.53 +/- 77.3 vs. 6.71 +/- 11.9; P<0.001) but not in ruptured plaques (43.3 +/- 64.4 vs. 30.1 +/- 60.9; P=0.117). CONCLUSIONS: These data suggest that continuous thinning of the fibrous cap is not an essential prerequisite for plaque rupture in ICA stenosis. Symptomatic, but not ruptured plaque, were associated with the highest number of apoptotic SMC. Thus, it seems unlikely that SMC apoptosis promotes plaque rupture by fibrous cap thinning.

Aged↗
PubMed2005

Influence of elastic and non-elastic external Dacron mesh support on para-anastomotic hypercompliance in end-to-end anastomoses.

OBJECTIVE: To quantify the influence of elastic and non-elastic external mesh support on para-anastomotic hypercompliance in end-to-end anastomoses (ex vivo). MATERIALS: Six end-to-end anastomoses prepared from ovine carotid arteries without mesh support and with external elastic and non-elastic dacron mesh support. METHODS: Compliance profiles of the anastomised arterial segments were measured successively, in the same anastomotic configuration without mesh support, with external elastic dacron mesh support and with external non-elastic dacron mesh support (randomized order). A pulsatile ex vivo perfusion system using a laser scan micrometer to monitor outer systolic and diastolic diameter was employed. RESULTS: Median pre-anastomotic and post-anastomotic hypercompliance without external mesh support were 1.45 and 1.19%/100 mmHg, respectively, above reference compliance. Use of the elastic mesh support significantly reduced the median hypercompliance to 0.68%/100 mmHg (pre-anastomotic) and to 0.34%/100 mmHg (post-anastomotic) above reference compliance. The non-elastic mesh support caused approximately the same significantly reduced median hypercompliance to 0.53%/100 mmHg (pre-anastomotic) and 0.43%/100 mmHg (post-anastomotic). CONCLUSIONS: Both elastic and non-elastic external mesh support significantly reduced pre- and post-anastomotic hypercompliance.

Anastomosis, Surgical↗
PubMed2002

Photodynamic therapy mediated induction of accelerated re-endothelialisation following injury to the arterial wall: implications for the prevention of postinterventional restenosis.

OBJECTIVE: Accelerated re-endothelialisation may inhibit the development of restenosis. Basic Fibroblast Growth Factor (bFGF) plays a key role for early proliferative activity in the artery following injury. Therefore, this study was devised to examine the effect of photodynamic therapy (PDT) on post-injury re-endothelialisation in vivo, and bFGF-mRNA expression in endothelial cells (EC) in vitro. MATERIALS AND METHODS: Rat carotid arteries were balloon-injured prior to PDT. Arteries were analysed after 1, 3, 5, 14 and 30 days. Morphometric measurements were undertaken following injection of 0.5% Evans Blue which stains non-endothelialised surfaces only. To identify EC, immunohistochemistry (CD-31) was performed. Proliferation was assessed by fluorescence cell counting. PCR quantification of bFGF-mRNA expression and proliferation were assessed in bovine aortic EC which were plated on isolated, PDT-treated EC-derived extracellular matrix at (12), 24, 48 (72 h). RESULTS: Three days following PDT, arteries displayed significantly increased endothelial lining (p = 0.02), which was more pronounced at 5 (p = 0.03) and 14 days (p = 0.02). At 30 days no relevant differences between PDT and control were noted. EC proliferation on PDT-treated matrix was significantly increased at 24, 48, and 72 h (p = 0.0004), whereas bFGF-mRNA expression was significantly increased at 24 h only (p = 0.007). CONCLUSION: Post-injury PDT appears to accelerate re-endothelialisation. Expression of bFGF-mRNA, however, although increased shortly after PDT, may not be responsible for a constant stimulation of EC proliferation.

Animals↗
PubMed2001

[Repeat rupture of covered rupture of non-anastomotic false aneurysm after femoropopliteal bypass].

For arterial reconstructions veins or alloplastic vascular prostheses are used. Nonanastomotic pseudoaneurysms of vascular protheses are a rare event. Breaks of the suture material, structural defects of the transplant fabric or degenerative modifications in the recipient vessel can cause nonanastomotic or anastomotic pseudoaneurysms. Such pseudoaneurysms are known from early clinical application of ePTFE grafts. In the case presented a nonanastomotic rupture of a ePTFE graft is described with partial repair of the rupture site by fibroblasts and connective tissue, which prevented bleeding.

Anastomosis, Surgical↗
PubMed2001

Compliance in anastomoses with and without vein cuff interposition.

OBJECTIVE: to compare anastomotic compliance in end-to-side anastomoses with and without vein cuff interposition. Materials polytetrafluoroethylene graft to bovine carotid artery without (standard) and with vein interposition (Linton-patch and Miller-cuff). METHODS: zonewise compliance measurement of end-to-side anastomoses in an in-vitro circulation system. The zone most distal to the suture-line served as reference compliance. RESULTS: directly distal to the suture-line the compliance of the Linton-patch (5.6+/-1.6%/100 mmHg) and Miller-cuff anastomosis (5.2+/-1.1%/100 mmHg) more closely approached reference compliance (standard: 5.0+/-1.2, Linton-patch: 4.5+/-1.5, Miller-cuff: 4.9+/-1.0%/100 mmHg) than that of the standard anastomosis (7.9+/-3.0%/100 mmHg). The maximal compliance values of the Linton-patch (9.5+/-2.3%/100 mmHg) and Miller-cuff anastomoses (9.8+/-2.7%/100 mmHg) were significantly higher than that of the standard end-to-side anastomosis (7.9+/-3.0%/100 mmHg). However, maximal compliance was shifted from the zone directly distal to the suture line in the standard end-to-side anastomosis, to the vein cuff interposition in the Linton-patch and Miller-cuff anastomoses. CONCLUSION: the shift in maximal compliance to the wider portion of the anastomosis in the Miller-cuff and Linton-patch anastomoses may obviate reocclusion.

Anastomosis, Surgical↗
PubMed2001

Endovascular treatment of symptomatic carotid stenosis using stent placement: long-term follow-up of patients with a balanced surgical risk/benefit ratio.

BACKGROUND AND PURPOSE: Carotid endarterectomy (CEA) is not necessarily beneficial in all patients with symptomatic high-grade (>/=70%) internal carotid artery (ICA) stenosis. Independent risk factors modulate both the individual stroke risk under medical treatment and the combined stroke and death risk after CEA. Endovascular stenting of symptomatic ICA stenosis may be an alternative to CEA in patients with a balanced surgical risk/benefit ratio. METHODS: We included 43 patients (71% men; median age, 67 years) with a recently symptomatic ICA stenosis with >/=70% luminal narrowing in whom the individual sum of medical and surgical risk factors suggested a balanced surgical risk/benefit ratio (risk-modeling appraisal derived from the European Carotid Surgery Trial). After stenting of the stenosed ICA with distal balloon protection, the mean+/-SD follow-up, including clinical and ultrasonographic examinations, was 20+/-11.8 months, with a median number of examinations of 5 per patient. RESULTS: Recanalization of ICA stenoses was technically successful in 40 of 43 procedures (93%). Within the 30-day postinterventional period 1 death occurred (2.5%), and the combined stroke and death rate within follow-up was 5%. Except for 1 asymptomatic ICA occlusion, no restenosis >/=70% occurred during follow-up. CONCLUSIONS: ICA stenting in symptomatic patients with a balanced surgical risk/benefit ratio is technically feasible, with a low periprocedural risk of stroke or death. Furthermore, the risk of future stroke and rate of significant restenosis during long-term follow-up appears to be low, suggesting that ICA stenting may be useful in carotid revascularization and stroke prevention.

Aged↗
PubMed1998

Talc pleurodesis in recurrent pleural effusions.

BACKGROUND AND AIMS: The treatment of recurrent malignant pleural effusions is known to be difficult and varies from observation in asymptomatic patients to pleurectomy with varying results. This prospective study presents the efficacy and the limits of iodized talc pleurodesis in patients with malignant and non-malignant recurrent pleural effusions. METHODS: In a prospective trial talc pleurodesis was performed in 50 patients with recurrent pleural effusions (malignant effusions: n=36, non-malignant effusions: n=14). After insertion of a chest tube and complete re-expansion of the lung, 5 mg of talc and 3 mg of thymol iodine were installed with 0.5 ml of 1% xylocaine/kg body weight and 30 ml 0.9% saline solution. The chest tube was removed after an average time of 4 days and chest radiographs were performed 1 month after instillation to evaluate the efficacy of pleurodesis. RESULTS: Successful therapy was achieved in 31 of 33 patients (94%) with malignant effusions within a follow-up period of 7 months. Three patients died within 1 month after therapy due to progressive malignant disease. The treatment was successful in all cases of non-malignant effusions and complications did not occur in either group. CONCLUSIONS: These results indicate that pleurodesis with iodized talcum slurry is a simple and inexpensive method with high efficacy in controlling malignant and non-malignant pleural effusions.

Chest Tubes↗
PubMed1998

[History of surgical instruments: 8. Instruments and development of amputation technique exemplified by amputation sets from the middle of the 19th century].

The amputation of a limb is one of the oldest surgical procedures. However, in the course of medical history operative techniques and surgical instruments have been improved continuously. With an example of an amputation case of the last century we will summarize this development until the middle of the nineteenth century. Even in the first century Celsus gave a description of an amputation (circular cut). A major step in the development of the operative technique was the introduction of artery forceps by A. Paré in the sixteenth century. Nevertheless, due to a lack of analgesics and narcotics the operation had to take only a few minutes. Therefore the amputation was completed in one cut, i.e. detachment of the skin, muscles and bone at the same level. This technique known as "classic circular cut" was modified several times in the following period: in order to reduce suture tension Petit recommended to transect the skin first and the muscles and bone more proximal ("two-stage circular cut", 1718) and Bromfield approved to cut in turn the skin first, the muscles more proximal and the bone most proximal ("three-stage circular cut", 1773). Finally, Lowdham (1679), Verduyn (1696) and C. J. M. Langenbeck (1810) changed the operative technique to the effect that they used a soft-tissue flap in order to cover the bone without tension ("flap amputation").

Amputation, Surgical↗
PubMed1998

[Is the type of vessel wall change a risk factor in implantation of prostheses in the aortofemoral segment? Dilatative versus obliterating arteriopathy].

The question of what effect role obliterative vessel disease has on postoperative outcome was analysed with the help of uni- and multivariate analysis. The univariate analysis showed significantly more preoperative risk factors in patients with obliterative vessel disease. Our multivariate analysis found three independent factors: ASA class, age, duration of surgery. Obliterative vessel disease seems to be a disadvantageous factor, but may be influenced by preoperative existing risk factor.

Aged↗
PubMed1997

[Long-term results of abdominal surgery interventions. Different evaluation from the viewpoint of the patient, the surgeon and the public health office].

The patient, the surgeon and the public health officer (Versorgungsamt) assess the long-term results of abdominal operations differently. We tried to objectivize these different assessments. The clinical data were collected retrospectively. Data on postoperative subjective state and degree of handicap were obtained in a written patient survey (March 1995). Two groups with benign diseases and one group with malignant disease were examined: 59 patients who had undergone sigmoidectomy for diverticulitis (30 female and 29 male patients, median age: 61.5 years), 347 patients subjected to proximal gastric vagotomy for duodenal ulcers (72 female and 275 male patients, median age: 46 years) and 158 patients who had undergone gastrectomy for gastric carcinoma (56 patients female, 102 patients male, median age: 61 years). The public health officer, classed 35.6% of the patients who had undergone sigmoidectomy and 34.6% of the patients who underwent vagotomy as officially handicapped with a stated grade of disablement, 77.2% of the patients with gastrectomy were officially classed as handicapped. When other diseases were taken into account in addition, 27.1% of the patients who had undergone sigmoidectomy, 27.4% of those who had undergone vagotomy and 75.9% of the patients with gastrectomy had received passes officially identifying them as severely handicapped persons. In the vast majority of cases, the combination of several different ailments had resulted in recognition of a graded handicap and severely disabled person's pass, skeletal, cardiac and circulatory ailments being the most frequent. In spite of this, the evaluation of post-operative course by our patients, the surgeon and the public health officer (as reflected in the official state classification) in terms of the degree of handicap clearly differed.

Adult↗
PubMed1997

[Changes in biomechanical properties of biological and synthetic prostheses].

Arterial compliance which is an expression of the structural properties of the vessel wall is defined as the fractional change in diameter in response to a unit change in pressure. It is likely to play an important role as a predictive parameter for maintenance of arterial reconstruction. Usually, vascular grafts are implanted with an arbitrarily applied longitudinal tension. The current study was designed to evaluate in vitro the effects of longitudinal tension on the dynamic circumferential compliance of different Dacron, Polytetrafluorethylene, Polyurethane and newly developed synthetic vascular grafts as well as arteries and veins. Longitudinal tensions between 0 and 1000 g were applied. Different grafts showed characteristic peak compliance values due to the used graft material, fabrication and extent of tension. Concerning their different compliance-tension profiles two groups of vascular grafts could be differentiated: 1) grafts which develop best compliance values after implementation of longitudinal traction and 2) prostheses which gain optimal biomechanical properties without any traction. There is strong evidence for modulation of compliance by implementation of longitudinal tension which suggests that it is useful to improve long term patency of arterial reconstruction.

Biomechanical Phenomena↗
PubMed1996

Tumors after renal transplantation.

The purpose of this retrospective study was to analyze the development of malignancies after renal transplantation. 633 renal graft recipients with an organ function longer than 1 year were followed up over a mean period of 67.6 +/- 48.7 months. Only 12 recipients received grafts from living-related donors. 38 recipients (6.0%) exhibited cancer of either the skin, the genitourinary system, the bronchial system, the female breast, or the colon. All tumors were de novo malignancies. The number of patients developing a tumor was significantly higher in the cyclosporine-treated group than in patients with conventional immunosuppression. 15 patients died within a mean survival time of 7.7 +/- 12.1 months. The frequency of disorders makes it necessary for organ transplant recipients to have routine examinations both before and at regular intervals after transplantation. This includes examination of the patient's skin, native kidneys and cervical smears for females.

Adolescent↗
PubMed1996

[Current treatment strategy in malignant pleural effusion].

Malignant pleural effusions are a grave consequence of advanced cancer disease. The successful suppression of pleural fluid reaccumulation can make a major contribution to the management and palliative care of patients with disseminated cancer. Many treatment concepts have been reported in the literature. The recommended therapy in malignant pleural effusions consists of intrapleural instillation of a sclerotic agent to produce pleurodesis. Different substances have been used, including tetracyclines, cytostatic agents, fibrin, talc, Corynebacterium parvum, cytokines and others. We reviewed the most frequently used techniques of pleurodesis in order to define the most effective treatment concept. In 15 prospective randomized trials the success rates varied from 13% with bleomycin to 100% with talc or Corynebacterium parvum. Talc was superior to other agents in 6 of 6, Corynebacterium parvum in 3 of 4 and bleomycin or tetracycline only in 3 of 8 studies. Adverse effects were frequently observed with cytostatic agents, but were very rare in the case of talc or fibrin instillation. Comparing the recently published data pleurodesis with talc appears to be the most effective treatment strategy, followed by Corynebacterium parvum, bleomycin and tetracycline.

Antibiotics, Antineoplastic↗
PubMed1996

[Talc pleurodesis in recurrent malignant pleural effusion--a prospective follow-up study].

Talc pleurodesis was performed in a prospective trial in 38 patients with recurrent malignant pleural effusion. After insertion of a chest tube a slurry containing 8g of iodined talcum, 0.5 ml of 1% xylocain/kg/body weight, and 80 ml of 0.9% NaCl was administered and suction drainage was performed. The chest tube could be removed after 4 +/- 1.7 days. A successful therapy could be achieved in 33/38 patients (86.8%). 2 patients (5.3%) suffered from recurrent pleural effusion which only in 1 case had to be drained. 3 patients died within the first month after talc pleurodesis due to an advanced cancer stage. Complications did not come to evidence in any case.

Adult↗
PubMed1996

[Preliminary results of a prospective randomized study vascular replacement above the knee].

In case of insufficient or missing greater saphenal vein or if the saphenal vein might be of important use for future bypass grafts, the question arises which alternative bypass material is the more appropriate choice. A literature review to that topic produced only unsatisfactory results. In a prospective randomized controlled clinical study (n = 250 patients) we compare the patency rates of either PTFE or Dacron as bypass material for femoropopliteal P-I-Bypass in chronic arterial occlusive disease. A preliminary evaluation of n = 103 patients (PTFE n = 52; Dacron n = 51) reveals an operative and immediate mortality rate of 0% and a loss of limb rate of 3.9% (PTFE) and 3.8% (Dacron). The secondary cumulative patency rate after 540 days of observation is 79.6% (PTFE) and 87.1% (Dacron). We so far find no statistically significant difference between both graft materials.

Adult↗