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Biomedical subjects

Wolfgang Schareck

Publications and source records attributed to Wolfgang Schareck.

13 recordsLinked to original sources
PubMed2006

Iliac anastomotic stenting with a biodegradable poly-L-lactide stent: a preliminary study after 1 and 6 weeks.

PURPOSE: To assess the technical feasibility, thrombogenicity, and biocompatibility of a new biodegradable poly-L-lactic acid (PLLA) anastomotic stent. METHODS: A polytetrafluoroethylene bifurcated graft was implanted in 17 pigs through a midline abdominal incision. After transverse graft incision, 17 316L stainless steel stents and 17 PLLA stents were randomly implanted at both iliac anastomotic sites and deployed with a 6-mm balloon under direct vision without angiography. Intended follow-up was 1 week in 6 pigs receiving oral acetylsalicylic acid (ASA) and in 7 pigs receiving ASA/clopidogrel; 4 pigs receiving ASA/clopidogrel were followed for 6 weeks. At the end of the study, the segments containing the stents were surgically explanted and processed for histology to measure the mean luminal diameter, intimal thickness, and the vascular injury and inflammation scores. RESULTS: Initial technical success of stent placement was achieved in all animals without rupture of the suture. Two pigs died (unrelated to the stent) at 3 days after operation (1 in groups A and B). At 1 week, all PLLA stents showed thrombotic occlusion with the use of ASA alone. In contrast, all PLLA stents remained patent with concurrent administration of ASA/clopidogrel. All metal stents were patent regardless of the antiplatelet regimen. The mean luminal diameter of patent PLLA stents (4.13+/-0.17 mm) was comparable to metal stents (4.27+/-0.35 mm, p=0.78) at 1 week, but significantly diminished at 6 weeks (3.21+/-0.44 versus 4.19+/-0.18 mm, p=0.005). Histological analysis showed no signs of excessive recoil. PLLA stents induced a higher inflammation score (1.79+/-0.56) and more intimal hyperplasia (0.34+/-0.11 mm) compared to metal stents [1.27+/-0.44 mm (p<0.001) and 0.18+/-0.04 mm (p=0.006), respectively] at 6 weeks. Vascular injury was comparable between PLLA and metal stents. CONCLUSION: Biodegradable PLLA stents showed higher thrombogenicity and reduced patency compared to metal stents during early follow-up. Although ASA and clopidogrel prevented thrombotic occlusion, the increased inflammatory response and neointima formation remain major concerns of PLLA stents. A solution to this problem might be the incorporation of anti-inflammatory drugs into the PLLA stent.

Absorbable Implants↗
PubMed2006

Iliac anastomotic stenting with a sirolimus-eluting biodegradable poly-L-lactide stent: a preliminary study after 6 weeks.

PURPOSE: To assess technical feasibility and biocompatibility of a new biodegradable sirolimus-eluting poly-L-lactide (PLLA) vascular anastomotic stent. METHODS: A polytetrafluoroethylene bifurcated graft was implanted in 9 pigs through a midline abdominal incision. After transverse graft limb incision, 6 unloaded PLLAs, 6 sirolimus-loaded PLLAs, and 6 unloaded stainless steel (316L) stents were randomly implanted at both iliac anastomotic sites. Stents were deployed with a 6-mm balloon under direct vision without the use of angiography. Prior to sacrifice after 6 weeks, contrast-enhanced computed tomography (CT) was performed to determine patency of the target vessels. Stented segments were surgically explanted and processed for histology to measure the mean luminal diameter and intimal thickness and to assign vascular injury and inflammation scores. RESULTS: No animals were lost during the study period. All stented graft limbs were patent on CT and histology. At the anastomotic sites and iliac arteries, the mean luminal diameter of SIR-PLLA stents (4.11+/-0.15 and 4.08+/-0.13 mm, respectively) were comparable to metal stents (4.23+/-0.35 and 4.21+/-0.26 mm, respectively), but significantly higher compared to unloaded PLLA stents [3.32+/-0.56 mm (p<0.001) and 3.29+/-0.39 mm (p=0.013), respectively]. At the iliac arteries, the mean intimal thickness was significantly lower with SIR-PLLA stents (0.09+/-0.02 mm) compared to unloaded PLLA stents (0.31+/-0.15 mm, p<0.001) and metal stents (0.19+/-0.04 mm, p=0.004). Vascular injury scores demonstrated only mild vascular trauma for all stents (SIR-PLLA: 0.42+/-0.63, PLLA: 0.51+/-0.62, metal: 0.50+/-0.62). Only mild inflammatory reaction was noted around SIR-PLLA stent struts (1.14+/-0.46), which was comparable to metal stents (1.27+/-0.45) but significantly lower than PLLA stents (1.79+/-0.56, p<0.001). CONCLUSION: SIR-PLLA stents showed comparable luminal diameter compared to metal stents, so incorporating sirolimus could reduce the inflammatory and neointimal response to PLLA stents. These findings need to be assessed with longer follow-up to confirm maintenance of efficacy.

Absorbable Implants↗
PubMed2005

INvestigation of STEnt grafts in patients with type B Aortic Dissection: design of the INSTEAD trial--a prospective, multicenter, European randomized trial.

PURPOSE: This study describes the design of an ongoing randomized trial initiated to compare the 2-year outcome of uncomplicated type B aortic dissection when treated by endovascular implantation of a Medtronic Talent stent graft adjunctive to best medical treatment versus best medical treatment alone. METHODS: Patients older than 18 years with type B aortic dissection as diagnosed by computed tomography or magnetic resonance angiography are randomized to either a thoracic aortic endoprosthesis and antihypertensive treatment, called "stent grafting," or a tailored antihypertensive treatment, called "medical treatment." Only patients in a clinically stable condition and without spontaneous thrombosis of the false lumen after 14 days of the index dissection are considered eligible for study inclusion. RESULTS: Primary outcome measure is all-cause mortality. Secondary outcome variables include conversion to stent and/or surgery, induced thrombosis of the false lumen, cardiovascular morbidity, aortic expansion (>5 mm/y of maximum diameter including true and false lumina), quality of life, and length of intensive care unit and hospital stay. The study design calls for 136 patients to be randomized and monitored for 24 months. CONCLUSIONS: The INSTEAD trial is the first randomized trial investigating the role of endoluminal treatment of uncomplicated type B aortic dissection. By the end of December 2004, 125 patients were randomized, accounting for 92% of the target. Final results of the INSTEAD trial should be available in 2006.

Aged↗
PubMed2005

Axillary-axillary interarterial chest loop conduit as an alternative for chronic hemodialysis access.

OBJECTIVE: After exhaustion of all conventional arteriovenous (AV) access options, an alternative approach is an arterioarterial conduit. The purpose of this study was to examine the utility of an axillary-axillary (AA) interarterial (IA) access in this subset of patients. METHODS: A retrospective review was performed of all patients who underwent placement of an AA IA access. Patients were observed for functional aspects and complications. Outcomes were determined according to the Society for Vascular Surgery/American Association for Vascular Surgery standards for reports for dealing with AV accesses. RESULTS: Twenty patients (median age, 59 years; range, 41-82 years) underwent AA IA access placement under general anesthesia between May 2001 and December 2004. Exhausted upper extremity AV access options were found in 14 patients (70%), with central vein occlusion in 5 patients (25%), and 12 patients (60%) had ischemia from steal syndrome. High-output cardiac failure was present in one patient. Median follow-up was 7.4 months (range, 0.5-45.3 months). The 30-day perioperative mortality rate was 5%. There was one (5%) early access thrombosis that resulted in moderate ischemia. Late access thrombosis occurred in three patients (15%), and all cases were asymptomatic. Early postoperative bleeding necessitated surgical intervention in four patients (20%). Late graft infection (n = 1; 5%) occurred after repeated thrombectomy. The primary and secondary patency rate was 90% and 93%, respectively, at 6 months. CONCLUSIONS: This short-term initial study showed that the AA IA loop access could be implanted with acceptable perioperative morbidity and with an excellent secondary patency rate. Further follow-up is necessary to determine the long-term complication rate and to allow more reasonable comparison with other methods of access.

Adult↗
PubMed2004

Long-term follow-up of 78 simultaneous pancreas-kidney transplants at a single-center institution in Europe.

BACKGROUND: The objective of this study was to determine the long-term results after simultaneous pancreas-kidney transplantation (SPK) at a single-center institution in Europe. PATIENTS AND METHODS: Seventy-eight consecutive patients with insulin-dependent diabetes mellitus and end-stage nephropathy were followed for a median of 7 years after SPK. Immunosuppressive protocol consisted of cyclosporine A, azathioprine, prednisone, and antithymocyte globulin. Multivariate Cox proportional hazard model was used to investigate the impact of different putative risk factors on long-term patient survival. Health-related quality of life was assessed by a validated questionnaire (SF-36). RESULTS: Patient survival at 5 and 10 years was 81% and 67%, respectively. Pancreas function rate was 73% and 60% and kidney function 67% and 44%, respectively. In multivariate analysis, preexisting myocardial infarction (relative risk [RR] 5.1, 95% confidence interval [CI] 1.5-16.6) and amputation (RR 3.7, 95% CI 1.1-12.9) were strongly associated with a diminished long-term patient survival. Analysis of patients with long-term functioning pancreas and kidney grafts revealed excellent results for quality of life posttransplant that were comparable with average scores of the normal German population. CONCLUSIONS: This series representing the largest experience with long-term follow-up in Europe confirms an excellent long-term survival and an exceptional quality of life after SPK.

Adult↗
PubMed2004

Brain death impairs pancreatic microcirculation.

Brain death (BD) influences the quality of donor grafts in transplantation. To evaluate the impact of BD on pancreas grafts, we investigated the influence of BD on the microcirculation and histology of the pancreas in a rat model of explosive BD. A group of Wistar rats (n=7), rendered brain dead by inflating an intracranially inserted Fogarty catheter was compared with controls (CO) using intravital epifluorescence-microscopy over 4 h after BD induction; functional capillary density (FCD), leukocyte adherence (AL) in post-capillary venules, histology and pancreatic enzymes were investigated. Four hours after BD, FCD decreased (333 +/- 11 vs. baseline 444 cm/cm2 +/- 5 SEM; p<0.01) and showed lower values than CO (388 +/- 9 p<0.01). In BD, AL was increased (628 cells/mm2 +/- 110 SEM vs. baseline 123 +/- 32, and vs. CO 180 +/- 33; p<0.001). BD caused increased histological damage (CO 1.6 score-points +/- 0.7 SD vs. BD 8.3 +/- 7.1; p<0.05). Amylase was higher in BD (p<0.05) but did not reach pathological values. We show for the first time that BD causes relevant changes in pancreatic microcirculation, histology and leukocyte endothelial interaction which might have a serious impact on the function of grafts. New strategies for preventing this damage are therefore highly desirable in order to improve the outcome of pancreas transplantation.

Amylases↗
PubMed2003

Endotoxin preconditioning in pancreatic ischemia/reperfusion injury.

OBJECTIVES: Prospective organ donors are exposed to various stress types. The effect of endotoxin pretreatment (ETX) on pancreatic ischemia/reperfusion injury (IRI) is unclear. We investigated, using a rat model of pancreatic IRI of an in situ isolated pancreatic tail segment, the effect of ETX on postischemic microcirculation and organ damage. METHODS: Twenty-four hours before pancreatic dissection, either intraperitoneal application of ETX (1 mg/kg in 0.9% NaCl) or saline only (control) was performed. Two-hour normothermic ischemia of the pancreatic tail was induced by clamping the splenic vessels and was followed by a reperfusion period of 2 hours. Microcirculatory parameters were measured by intravital epifluorescence microscopy [functional capillary density (FCD), adherent leukocytes (ALs), and histology]. The presented data represent the mean +/- SEM/SD as appropriate. RESULTS: ETX pretreatment caused a significantly greater decrease in FCD (497 +/- 6 cm/cm2 baseline versus 326 +/- 15 cm/cm2 2 hours of reperfusion) compared with controls (498 +/- 8 versus 258 +/- 15 cm/cm2) 2 hours after reperfusion (P < 0.01). Two hours after reperfusion, ALs were significantly decreased in ETX animals compared with controls (ETX: 141 +/- 37 versus 273 +/- 36 cells/mm2, P < 0.05). Histologic damage was less in ETX (6.4 score points +/- 0.32 versus 8.8 +/- 0.33 control, P < 0.05). CONCLUSION: ETX preconditioning decreases microcirculatory deterioration caused by IRI by means of less loss of nutritive tissue perfusion, decrease in ALs, and less histologic damage. This indicates a protective effect of ETX preconditioning in pancreatic IRI.

Animals↗
PubMed2003

Inhibitory effects of human and porcine alpha-amylase on CCK-8-stimulated lipase secretion of isolated rat pancreatic acini.

Previously we have demonstrated inhibitory effects of the plant lectin wheat germ agglutinin (WGA) on (125)I-CCK-8 binding to pancreatic AR42J cells as well as on CCK-8-stimulated Ca(2+) release and alpha-amylase secretion of rat pancreatic acini or acinar cells. Therefore, it is entirely conceivable that alpha-amylase having several lectin-like carbohydrate recognition domains can modulate the CCK-8 stimulated lipase secretion. Human alpha-amylase, purified from pancreatic juice by affinity chromatography to homogeneity, and commercial porcine pancreatic alpha-amylase inhibit CCK-8-stimulated lipase secretion of rat pancreatic acini in a concentration-dependent manner. Acarbose, a specific inhibitor of alpha-amylase, was without effect on CCK-8-induced cellular lipase secretion. The data presented here provide evidence for a regulatory function of alpha-amylase in CCK-8-stimulated pancreatic secretion.

Agglutination Tests↗
PubMed2003

Anti-oxidant ebselen delays microvascular thrombus formation in the rat cremaster muscle by inhibiting platelet P-selectin expression.

Ebselen, a seleno-organic compound showing glutathione per-oxidase-like activity, has potent anti-inflammatory and anti-oxidant effects. Since selenium deficiency is thought to be associated with an increased incidence of vascular thrombosis, we studied the effect of ebselen on blood cell aggregate formation and vessel occlusion in vivo. In individual microvessels of rat cremaster muscle preparations, photochemically induced thrombus formation was analyzed in detail using intravital fluorescence microscopy. In ebselen-pretreated animals (30 mg/kg ip), venular thrombus formation was significantly delayed (50% vessel occlusion: 535+/-34 s; initial stasis: 872+/-82 s; complete occlusion: 908+/-87 s) as compared to vehicle-treated controls (416+/-42; 612+/-49; 647+/-51). Moreover, ebselen significantly prolonged the kinetics of arteriolar thrombus formation and even completely prevented blood cell aggregate and thrombus formation in 88.9% of all arterioles studied (p<0.05 vs controls: 37.5%). Anti-thrombotic properties of ebselen could also be observed in a model of ferric chloride-induced microvascular thrombosis, with a low dose (5 mg/kg ip) being as effective as a high dose pretreatment (30 mg/kg ip). As assessed by flow cytometry of platelet P-selectin immunfluorescence, whole blood isolated from ebselen-treated animals revealed a significantly lower fraction of P-selectin expressing platelets when compared with that of DMSO-treated controls. In addition, oxidant stress-induced upregulation of P-selectin on isolated platelets was found dose-dependently inhibited by increasing concentrations of ebselen (10-100 micro M). Moreover, ebselen dose-dependently inhibited H(2)O(2)-induced platelet-leukocyte aggregate formation in whole blood in vitro, suggesting that the anti-thrombotic effect of ebselen is achieved by attenuation of P-selectin dependent platelet-leukocyte aggregation. Thus, ebselen represents preventive and therapeutic value for disorders with increased risk for oxidant stress-associated thrombotic events.

Animals↗
PubMed2003

[Routine use of Brener shunt during carotid endarterectomy].

OBJECTIVE: To evaluate the routine use of Brener shunt during carotid endarterectomy (CEA). METHODS: A prospective audit of the results of 58 consecutive CEA was performed, with routine use of Brener shunt in surgical hospital, Rostock university in Germany. Intraoperative and postoperative complications of CEA were reviewed. RESULTS: In this study, the successful rate of insertion of shunt was 100%. The perioperative stroke/death rate at 30 days was 0, but the TIA rate was 2 cases (3.5%), which was related with previous stroke and contralateral internal carotid occlusion. 2 cases (3.5%) had minor operative complications. CONCLUSIONS: The routine use of Brener shunt has a less rate of intraoperative and early postoperative neurologic complications during CEA. But experience in a large number of shunting procedure is needed.

Aged↗
PubMed2002

Celiac axis stenosis in pancreatic head resection for chronic pancreatitis.

BACKGROUND AND AIMS: To determine the outcome of pancreatic head resection for chronic pancreatitis in the presence of celiac axis stenosis or occlusion we analyzed the blood supply of the upper abdominal organs in 11 patients before and after surgery. PATIENTS AND METHODS: Between March 1994 and April 2000 we performed 145 pancreatic head resections for chronic pancreatitis. Preoperatively 11 patients showed celiac axis stenosis at angiography. All 11 patients underwent duplex ultrasonography postoperatively and 8 had magnetic resonance angiography during follow-up. RESULTS: In two cases division of the median arcuate ligament was performed to reestablish hepatic artery blood flow. No further revascularization procedures of the celiac axis were necessary. Postoperative duplex ultrasonography and magnetic resonance angiography showed normal blood flow in five patients. Four patients still had an occlusion or a significant celiac axis stenosis, and two had a stenosis only during expiration. At follow-up nine patients were completely free of abdominal pain (82%), and all had gained weight postoperatively, ranging from 5 to 16 kg. CONCLUSIONS: Our data suggest that celiac axis stenosis infrequently causes complications in pancreatic head resection for chronic pancreatitis and therefore does not represent a contraindication for this procedure. Nevertheless the hepatopedal blood flow must be confirmed by palpation or duplex ultrasonography after pancreatic head resection in these patients.

Celiac Artery↗