Biomedical subjects

Christel Weiss

Publications and source records attributed to Christel Weiss.

At least 19 recordsLinked to original sources

PubMed2006

Effect of nicardipine prolonged-release implants on cerebral vasospasm and clinical outcome after severe aneurysmal subarachnoid hemorrhage: a prospective, randomized, double-blind phase IIa study.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the effect of nicardipine prolonged-release implants (NPRIs) on cerebral vasospasm and clinical outcome after severe subarachnoid hemorrhage. METHODS: Thirty-two patients with severe subarachnoid hemorrhage and undergoing aneurysm clipping were included into this single center, randomized, double-blind trial. Sixteen patients received NPRIs implanted into the basal cisterns in direct contact to the exposed proximal blood vessels; in 16 control patients, the basal cisterns were opened and washed out only without leaving implants. Angiography was performed preoperatively and at day 8+/-1. Computed tomography imaging was analyzed for the incidence of territorial infarcts unrelated to surgery. Patient outcome was assessed using the modified Rankin and National Institute of Health Stroke scales. RESULTS: The incidence of angiographic vasospasm in proximal vessel segments was significantly reduced after implantation of NPRIs (73% control versus 7% NPRIs). Significant differences occurred also for the majority of distal vessel segments. Computed tomography scans revealed a lower incidence of delayed ischemic lesions (47% control versus 14% NPRIs). The NPRI group demonstrated more favorable modified Rankin and National Institute of Health Stroke scales as well as a significantly lower incidence of deaths (38% control versus 6% NPRIs). CONCLUSIONS: Implantation of NPRIs reduces the incidence of cerebral vasospasm and delayed ischemic deficits and improves clinical outcome after severe subarachnoid hemorrhage.

Adult↗

PubMed2006

Hypothermia-induced loss of endothelial barrier function is restored after dopamine pretreatment: role of p42/p44 activation.

BACKGROUND: Donor dopamine usage is associated with improved immediate graft function after renal transplantation. Although prolonged cold preservation results in an increased vascular permeability, the present study was conducted to examine in vitro and in vivo if dopamine pretreatment influences endothelial barrier function under such conditions. METHODS: To assess cold preservation injury in vitro and in vivo, cultured human umbilical vein endothelial cells (HUVEC) and Lewis donor rats were pretreated with dopamine or isotonic saline prior to cold storage. Injury was determined by lactate dehydrogenase (LDH) release, histology, and functional analysis. RESULTS: In vitro cold storage resulted in intercellular gap formation in both untreated and dopamine pretreated HUVEC. In the latter monolayer integrity was completely restored upon rewarming and paracellular transport of fluorescein isothiocyanate-dextran was significantly reduced. In dopamine treated HUVEC, intercellular gap formation was independent of cell death and was associated with redistribution of junctional proteins and condensation of cytoskeleton proteins. In untreated HUVEC proteolysis and cell death were clearly evident after hypothermia. Closing of intercellular gaps was dependent on p42/p44 activation. Regeneration of adenosine triphosphate was only observed in dopamine pretreated cells. Only in dopamine treated Lewis renal allografts subjected to cold storage, activation of p42/p44 occurred upon rewarming. These grafts had a better renal function and displayed less inflammatory cells five days after transplantation. CONCLUSION: Our study demonstrates beneficial effects of dopamine treatment on cold storage induced endothelial barrier disturbances. This may contribute to the positive effects of catecholamines on immediate graft function of renal allografts in men.

Cells, Cultured↗

PubMed2006

The fading of reported effectiveness. A meta-analysis of randomised controlled trials.

BACKGROUND: The "real" effect size of a medical therapy is constant over time. In contrast, the effect size reported in randomised controlled trials (RCTs) may change over time because the sum of all kinds of bias influencing the reported effectiveness is not necessarily constant. As this would affect the validity of meta-analyses, we tested the hypothesis that the reported effect size decreases over time. Furthermore, we tested three hypotheses that would explain a possible change. METHODS: Because of well established outcome measures, the lipid-lowering drugs Pravastatin and Atorvastatin (serum low-density lipoprotein cholesterol, LDL-C) and the anti-glaucoma drugs Timolol and Latanoprost (intraocular pressure, IOP) were chosen for this investigation. Studies were identified by a standardized MEDLINE search. RCTs investigating the above identified medications administered as monotherapy, and in defined dosages, were included. Publication year, baseline (= pre-treatment value in the treatment group of interest) and post intervention means, number of patients and the assignment to experimental or control group were extracted for each study. RESULTS: A total of 625 citations were screened; 206 met the inclusion criteria. The reported effect size of Pravastatin (change of reported effect size in five years: -3.22% LDL-C, P < .0001), Timolol (-0.56 mmHg, P < .0001) and Latanoprost (-1.78 mmHg, P = .0074) decreased over time, while there was no significant change for Atorvastatin (+0.31% LDL-C, P = .8618). Multiple regression analysis showed that baseline values were the most important influencing factor; study size or treatment group did not play a significant role. CONCLUSION: The effectiveness of medical therapies reported in RCTs decreases over time in three of the four investigated pharmaceuticals, caused mainly by baseline differences. We call this phenomenon "fading of reported effectiveness". Under this condition the validity of a meta-analysis may be impaired. Therefore we propose to observe this phenomenon in future meta-analyses in order to guarantee a maximum of transparency.

Adrenergic beta-Antagonists↗

PubMed2006

Persistent T-cell activation and clinical correlations in patients with ANCA-associated systemic vasculitis.

BACKGROUND: Although in antineutrophil cytoplasmic autoantibodies (ANCA)-associated systemic vasculitis (AASV) patients, activation of T-cells has been described, persistence of these alterations has not been well characterized. This study was conducted to define persistent T-cell activation (PTA) in AASV patients and to assess whether this correlates with disease activity, disease severity, age or therapy. METHODS: The expression of CD4, CD45RO, CD25, CD26, CD28, CCR7 and HLA-DR was examined longitudinally in 38 consecutive AASV patients. Clinical parameters were compared by univariate and multiple analysis and Kaplan-Meier curves for relapse-free survival were calculated. RESULTS: PTA could be defined as either of two activation phenotypes, i.e. a low percentage of CD4+ CD45RO- T-cells or a high percentage of CD25 in the naïve CD4+ population (n = 26), since only these phenotypes were stable over time and were not associated with active disease. In patients with PTA, major organ involvement was significantly more often found than in patients without PTA. Moreover, the cumulative cyclophosphamide dose (26.86 vs 8.53 P < 0.01) was significantly increased in these patients, suggesting that PTA was associated with disease severity. In general, patients with PTA were older than those without (62.92 +/- 9.4 years vs 48.42 +/- 16.9 years respectively, P < 0.01). PTA was independent of disease duration. Interestingly, patients with a low percentage of CD4+CD45RO- T-cells were significantly more often diagnosed as microscopic polyangiitis (P < 0.01). CONCLUSION: We identified two independent phenotypes of T-cell activation in AASV patients. These phenotypes are persistent and do not reflect disease activity. PTA predominantly occurs in patients with severe disease. This might explain the higher cumulative cyclophosphamide dose found in these patients.

Adult↗

PubMed2006

Incidence of recurrent venous thromboembolism of patients after termination of treatment with ximelagatran.

OBJECTIVE: Recurrent thromboembolic events may occur after termination of anticoagulant therapy for acute venous thromboembolism (VTE) using oral direct thrombin inhibitor ximelagatran. METHODS: Patients with VTE recruited at the German study centres were followed-up for an additional 18 months, treated initially with 2x36 mg ximelagatran daily or with enoxaparin/warfarin over 6 months (THRIVE Treatment study) and 2x24 mg ximelagatran daily or placebo over 18 months (THRIVE III study). Recurrent VTE and the combined outcome events consisting of recurrent VTE, other thrombotic complication, major bleeding and mortality were analysed. RESULTS: In the THRIVE Treatment study, no patient suffered from a recurrent VTE, but 1 patient randomised to enoxaparin/warfarin experienced major bleeding. During follow-up, 4/32 and 3/32 patients initially randomised to ximelagatran and enoxaparin/warfarin developed recurrent VTE (p=0.7024). No major bleed occurred. One patient in each group died. The incidences of the combined outcome events were not different (p=0.9326). In the THRIVE III study, 0/9 versus 5/14 patients randomised to ximelagatran and placebo developed recurrent VTE including 1 fatal pulmonary embolism (p=0.0501). During follow-up, 3/9 and no patients initially randomised to ximelagatran and placebo developed recurrent VTE. One and 3 other outcome events occurred in patients initially randomised to ximelagatran or placebo. During follow-up, recurrent VTE (p=0.6893) and combined outcome events (p=0.3642) were not different between the groups. CONCLUSION: The results of the follow-up studies suggest that thromboembolic events may re-occur in patients with acute VTE after termination of treatment with both vitamin K-antagonists and ximelagatran.

Administration, Oral↗

PubMed2006

Commercial mesh versus Nylon mosquito net for hernia repair. A randomized double-blind study in Burkina Faso.

PURPOSE: The goal of this study was to investigate whether locally available Nylon mosquito net might be a useful alternative to expensive commercial mesh implants for hernia repair, a clinical randomized double-blind study was performed. MATERIALS AND METHODS: Over a period of 3 months 35 patients with a total of 40 inguinal hernias were randomized for hernia repair with either a commercial graft (Ultrapro) or a piece of sterilized 100% Nylon mesh available as mosquito net in most African village markets. The surgeons' comfort in handling the meshes, the incidence of complications, and the patients' quality of life before and 30 days after hernia repair were evaluated. In addition, the costs of the two materials were compared. RESULTS: There was no significant difference in the clinical short-term outcome of the hernia treatment or the surgeons' comfort in handling the two different materials. The price of the locally bought Nylon mesh was 0.0043 US dollars as compared to 108 US dollars for the commercial mesh. CONCLUSIONS: In situations where superior results of hernia repair depend on the use of a mesh prosthesis but where commercial material is not available or affordable, the use of Nylon mosquito net may be an alternative. Further studies with a larger number of patients and longer follow-up are justified and recommended.

Adult↗

PubMed2006

Bipolar and multipolar radio frequency ablation with resistance controlled power output: standardized ex vivo kidney tissue evaluation.

PURPOSE: We investigated a newly developed bipolar and multipolar RF ablation system with an internally cooled electrode and resistance controlled power output in a standardized model of perfused ex vivo kidney tissue. MATERIALS AND METHODS: RF energy was applied at different power levels (20, 30 and 60 W) for 1, 3, 5 and 9 minutes. Each treatment parameter was repeated 5 times. For the 20/30 W levels a bipolar electrode with an active conducting part of 20/30 mm was selected. At 60 W 2 bipolar electrodes with an active conducting part (30 mm each) were connected. Lesion volumes and shapes were calculated by measuring the maximum vertical, long axis and short axis diameters of the macroscopic lesion. RESULTS: Lesion volume increased significantly with the treatment time and generator power applied (p < 0.0001). Lesion size in multipolar ablated zones was larger than that in bipolar ablated zones. A reliable dose-effect relationship existed between the generator power/applied treatment time and ablated tissue lesion size. All lesions were elliptical. CONCLUSIONS: Bipolar and multipolar RF ablation with an internally cooled electrode and tissue resistance control represent an interesting advance in RF technology. The development of lesion size and volume is predictable, while a uniform lesion shape can be achieved in perfused ex vivo kidney tissue. Further in vivo trials are required to test whether complete and reliable tumor tissue ablation is possible with this system.

Animals↗

PubMed2006

Magnetic resonance imaging for assessment of radiofrequency lesions in kidney tissue immediately after ablation: an experimental study.

BACKGROUND AND PURPOSE: Radiofrequency ablation (RFA) is an attractive minimally invasive treatment option for small renal masses. The purpose of this study was to investigate the morphologic imaging appearance of RF lesions immediately after the ablation of kidney tissue using standard clinical MR sequences, as well as to investigate the correlation between MR and gross lesion size. MATERIALS AND METHODS: Ablations were performed 17 times in a standardized model of ex-vivo perfused porcine kidneys using a resistance-controlled RF device (250 W, 470 kHz) and a nonexpandable bipolar applicator inserted into the center of healthy renal parenchyma. The RF current was applied for 9 minutes at 20 W. Imaging was performed after ablation using standard clinical MR sequences: morphologic T(1)/T(2)- weighted images and an isotropic post-contrast T(1) high-resolution measurement (VIBE). Maximum lesion diameters were measured in three directions and were compared with the measurements of the gross lesions. Histologic (hematoxylin + eosin and nicotinamide adenine dinucleotide staining) and statistical analyses were performed. RESULTS: The gross pathologic examination showed a firm, white-yellow ablation zone sharply demarcated from the untreated tissue. The histologic examination confirmed cellular viability outside but not in the treatment zone. The RF lesions were hyperintense on T(1)-weighted images and hypointense on T(2)-weighted images. The lesion size measured in the VIBE images correlated best with the macroscopic lesion size (N = 16). CONCLUSIONS: Morphologic MR T(1) and T(2) sequences of RF lesions immediately after ablation produce reliable and consistent imaging characteristics. The post-contrast, high-resolution sequence (VIBE) enables the extent of the lesion to be determined accurately. The potential uses of this imaging strategy in clinical practise warrant further investigation on human renal-cell carcinoma.

Animals↗

PubMed2006

Technical characterization of a new bipolar and multipolar radiofrequency device for minimally invasive treatment of renal tumours.

OBJECTIVE: To investigate the technical characteristics of a newly developed device for bipolar and multipolar radiofrequency ablation (RFA) of kidney tissue with a resistance-controlled power output. MATERIALS AND METHODS: The standardized model of the isolated perfused ex vivo porcine kidney was used. Two different applicators (20 and 30 mm active length) were selected for bipolar RFA, and one pair of applicators (2 x 30 mm active length) for multipolar RFA. RF energy was applied at different power levels (20, 30, 60 W) depending on the total active length of the electrodes. Treatment times were 1, 3, 5 and 9 min. The ablation cycles were recorded in continuous digital real-time and displayed on a monitor showing pre-set power, actual applied power, applied energy, tissue resistance, and impedance. Lesion sizes were measured macroscopically. A coagulation coefficient (coagulated tissue volume per applied energy unit) was calculated. RESULTS: There was a dosage-effect relationship between the generator power/treatment time and the sizes of the lesions. With increasing treatment time, less tissue volume was coagulated per unit of applied energy. The actual applied energy was lower than that calculated theoretically. The resistance and impedance values for the 30-W applicator were lower than those of the 20-W applicator. CONCLUSIONS: The technical features of this RFA device, with internally cooled bipolar and multipolar applicators and a resistance-controlled power output, represents an innovative improvement in RF technology. In vivo studies are needed to confirm the expected advantages and the suitability of this device for complete and reliable ablation of renal tumours.

Animals↗

PubMed2006

The role of the lymphatic system and its specific growth factor, vascular endothelial growth factor C, for lymphogenic metastasis in prostate cancer.

OBJECTIVE: To compare prostate carcinoma, with and with no lymph node metastasis, to benign prostatic hyperplasia (BPH) tissue for lymphatic vessel density (LVD) and the expression of the lymph-endothelial specific growth factor, vascular endothelial growth factor C (VEGF-C), to determine their role in lymphogenic metastasis. PATIENTS, MATERIALS AND METHODS: Lymphatic vessels were stained using lymphatic vessel endothelial hyaluronan receptor 1 and assessed in standard areas. The expression of VEGF-C was assessed by the number of positive epithelial cells. The data were compared with the clinical staging. RESULTS: The lowest LVD was found in tumorous areas as opposed to periphery and nontumorous tissue (P = 0.007; P < 0.001). The highest LVD was in BPH tissue (P < 0.001). There was no correlation with clinical staging. There was more VEGF-C staining in pN1 than in pN0 and in BPH specimens (P = 0.002). CONCLUSION: LVD is not a prognostic variable for the process of lymphogenic metastasis in prostate cancer. VEGF-C is up-regulated in prostate cancer and its correlation with lymph node status suggests a role for the development of lymph node metastasis, e.g. via an increased permeability of lymphatic vessels.

Aged↗

PubMed2005

IGF-II serum levels increase discrimination between benign prostatic hyperplasia and prostate cancer and improve the predictive value of PSA in clinical staging.

PURPOSE: IGF-I serum levels have been demonstrated as being associated with prostate cancer (PCa) and can serve as a predictive factor for the risk of PCa development. However, the role of IGF-II in PCa and its importance as a predictive marker is still unclear. Our aim was to determine PSA and IGF-II serum levels in patients with PCa and benign prostatic hyperplasia (BPH) and to analyse the value of IGF-II as an additional predictive factor in the diagnostics of PCa. METHODS: 112 patients who underwent surgery for BPH or PCa (no hormonal treatment, no further malignancies) were included in this study ((I) 38 PCa, PSA < or = 15 ng/ml; (II) 34 PCa, PSA > 15 ng/ml; (III) 40 BPH). Preoperative serum levels of total PSA and total IGF-II were determined by ELFA and ELISA, respectively. RESULTS: PSA levels were (I) 5.7+/-1.9 ng/ml; (II) 25.0+/-11.5 ng/ml and (III) 4.0+/-2.8 ng/ml. (II) was statistically associated with a high grading (2b/3; p = 0.0182), a high Gleason sum score (7-10; p = 0.0049) and a non-organ confined tumor (T3/4; p = 0.0009) compared to (I), all Chi2 test. IGF-II levels were significantly higher in PCa (I+II) compared to BPH (833.8+/-238.9 ng/ml vs. 633.3+/-141.4 ng/ml, p < 0.0001, t-test). Both PSA and IGF-II were associated with tumor staging (p = 0.0097, p = 0.0308; t-test). No significant correlation was observed between PSA and IGF-II levels. Logistic regression analysis revealed that the combination of PSA and IGF-II improves the prediction of tumor staging in PCa (p = 0.0175 and p = 0.0459, Wald test). Additionally, the combination of PSA and IGF-II can significantly increase discrimination between BPH and PCa; each p < 0.0001, Wald test. CONCLUSIONS: This study provides evidence that IGF-II serum levels may serve as an additional parameter for (a) improved determination of tumor staging and (b) better discrimination between BPH and PCa.

Aged↗

PubMed2005

Reduction of pain and fracture incidence after kyphoplasty: 1-year outcomes of a prospective controlled trial of patients with primary osteoporosis.

Previously, we reported significantly reduced pain and improved mobility persisting for 6 months after kyphoplasty of chronically painful osteoporotic vertebral fractures in the first prospective controlled trial. Since improvement of spinal biomechanics by restoration of vertebral morphology may affect the incidence of fracture, long-term clinical benefit and thereby cost-effectiveness, here we extend our previous work to assess occurrence of new vertebral fractures and clinical parameters 1 year after kyphoplasty compared with a conservatively treated control group. Sixty patients with osteoporotic vertebral fractures due to primary osteoporosis were included: 40 patients were treated with kyphoplasty, 20 served as controls. All patients received standard medical treatment. Morphological characteristics, new vertebral fractures, pain (visual analog scale), physical function [European Vertebral Osteoporosis Study (EVOS) score] (range 0-100 each) and back-pain-related doctors' visits were re-assessed 12 months after kyphoplasty. There were significantly fewer patients with new vertebral fractures of the thoracic and lumbar spine, after 12-months, in the kyphoplasty group than in the control group (P=0.0084). Pain scores improved from 26.2 to 44.4 in the kyphoplasty group and changed from 33.6 to 34.3 in the control group (P=0.008). Kyphoplasty treated patients required a mean of 5.3 back-pain-related doctors' visits per patient compared with 11.6 in the control group during 12 months follow-up (P=0.006). Kyphoplasty as an addition to medical treatment and when performed in appropriately selected patients by an interdisciplinary team persistently improves pain and reduces occurrence of new vertebral fractures and healthcare utilization for at least 12 months in individuals with primary osteoporosis.

Adult↗

PubMed2005

Prognostic value of plasma N-terminal pro-brain natriuretic peptide in patients with severe sepsis.

BACKGROUND: Increased plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) have been identified as predictors of cardiac dysfunction and prognosis in congestive heart failure and ischemic heart disease. In severe sepsis patients, however, no information is available yet about the prognostic value of natriuretic peptides. Therefore, the aim of the present study was to determine the role of the N-terminal prohormone forms of ANP (NT-proANP) and BNP (NT-proBNP) in the context of outcome of septic patients. Furthermore, the effect of treatment with recombinant human activated protein C [drotrecogin alfa (activated)] on plasma levels of natriuretic peptides in severe sepsis was evaluated. METHODS AND RESULTS: Fifty-seven patients with severe sepsis were included. Levels of NT-proANP and NT-proBNP were measured on the second day of sepsis by ELISA. Septic patients with NT-proBNP levels >1400 pmol/L were 3.9 times more likely (relative risk [RR], 3.9; 95% CI, 1.6 to 9.7) to die from sepsis than patients with lower NT-proBNP values (P<0.01). NT-proANP levels, however, were not predictive of survival in our patient population. A highly significant correlation was found between troponin I levels and plasma concentrations of NT-proBNP in septic patients (r=0.68, P<0.0001). In addition, troponin I significantly accounted for the variation in NT-proBNP levels (P<0.0001), suggesting an important role for NT-proBNP in the context of cardiac injury and dysfunction in septic patients. Twenty-three septic patients who received treatment with drotrecogin alfa (activated) presented with significantly lower concentrations of NT-proANP, NT-proBNP, and troponin I compared with patients not receiving drotrecogin alfa (activated). CONCLUSIONS: NT-proBNP may serve as useful laboratory marker to predict survival in patients presenting with severe sepsis.

APACHE↗

PubMed2005

Transjugular intrahepatic portosystemic shunts: adjunctive embolotherapy of gastroesophageal collateral vessels in the prevention of variceal rebleeding.

PURPOSE: To prospectively compare rebleeding rates in patients treated with transjugular intrahepatic portosystemic shunt (TIPS) creation alone and those treated with TIPS creation combined with adjunctive embolotherapy of gastroesophageal collateral vessels. MATERIALS AND METHODS: Informed consent and ethics committee approval were obtained. Between November 1991 and November 2002, the authors prospectively followed up 95 consecutive patients (61 men, 34 women; age range, 30-81 years) with variceal bleeding due to cirrhosis and portal hypertension. The patients were divided into two groups on the basis of splenoportographic findings after TIPS creation. The patients were treated with TIPS alone (group 1, 42 patients) or in combination with variceal embolotherapy (group 2, 53 patients). Embolotherapy with sclerosing agents in combination with coils was performed when varices continued to fill and the pressure gradient was more than 12 mm Hg. Rebleeding was defined as any hemorrhage necessitating a transfusion of 2 or more units of blood. Estimates for the cumulative patency, survival, and rebleeding rates were calculated by using life-table analysis; the log-rank test was used to compare the two treatment modalities. The prognostic relevance of treatment and selected variables with respect to rebleeding and survival were analyzed with multiple logistic regression. RESULTS: Mean follow-up time (+/- standard deviation) was 48.7 months +/- 37.8 (range, 1-127 months). The proportion of patients (Kaplan-Meier estimation) with TIPS who remained free of bleeding was 61% after 2 years and 53% after 4 years. Patients who underwent both the TIPS procedure and embolotherapy remained free of bleeding in 84% of cases after 2 years and in 81% of cases after 4 years. With respect to the rebleeding rate, the difference between the groups was statistically significant (log-rank test, P = .02). Results of multiple logistic regression analysis showed that variceal embolotherapy significantly reduced the risk of rebleeding (Wald test, P < .001). CONCLUSION: The results suggest that TIPS and adjunctive embolotherapy of gastroesophageal collateral vessels significantly lower the rebleeding rate in comparison to TIPS alone.

Adult↗

PubMed2005

Comparison of two different ecarin clotting time methods.

BACKGROUND: Ecarin Clotting Time (ECT) assay specifically determines the inhibition of meizothrombin by direct thrombin inhibitors (DTI). Blood coagulation factor levels lowered by vitamin K antagonists (VKA) may prolong ECT. Concomitant treatment of VKA with DTI may influence differently the two published ECT methods. METHODS: Lepirudin (100-3,000 ng/ml), argatroban (300--3,000 ng/ml) and melagatran (30--1000 ng/ml) were added to normal plasma (NP; n=12) samples and to plasma of patients on stable vitamin K antagonist therapy with warfarin (VKAP; n=12). ECT assays were performed according to [5] (method 1) and according to [6] (method 2). Data were subjected to multifactorial variance analysis. RESULTS: Normal ranges were 35.5+/-2.8 s in NP versus 31.8+/-1.2 s in VKAP with method 1 (p< 0.001) and 44.3+/-3.9 s in NP vs. 51.4+/-8.3 s in VKAP with method 2 (p< 0.004). Besides the inhibitors (p<0.0001), the method used (p<0.0001) and the group (NP vs. VKAP, p=0.003) had an influence on the ECT. Inhibitors (p< 0.02) or method used (p< 0.03) and the group (NP vs. VKAP, p=0.0001) influenced also the ECT ratio. DISCUSSION: Both ECT methods are suitable for monitoring different DTIs over a large linear range with both methods during concomitant treatments with vitamin K antagonists. The ECT ratio improves but not abolishes the differences between the methods. Additive effects of vitamin K antagonists on ECT methods have to be taken into consideration in clinical routine.

Antithrombins↗

PubMed2005

Minimally invasive treatment of renal cell carcinoma: comparison of 4 different monopolar radiofrequency devices.

OBJECTIVES: Radiofrequency Ablation is an investigational treatment option for RCC. The aim of our study was to test the ablation algorithms of four different RF systems in a standardized ex vivo perfused porcine kidney model. MATERIALS AND METHODS: A multiline monopolar dry electrode (impedance-based system), a multiline monopolar dry electrode (temperature-based system), a single monopolar wet electrode (impedance-based system) and a single monopolar dry, internally-cooled electrode (impedance-based system) were selected. RF energy was applied at different treatment parameters (power with and without control, tissue temperature, saline enhancement) for 1, 3, 5 and 9 minutes in healthy perfused ex vivo porcine tissue. Each treatment parameter was repeated 5 times. Maximum vertical, long-axis and short-axis diameters of the macroscopic lesion were measured and lesion volumes/ shapes were calculated. RESULTS: Lesion volumes increased significantly with the pre-selected tissue temperature and saline enhancement. Saline enhancement created larger, but irregular shaped lesions. The impedance-based system created lesion volumes that were predictable by treatment time and generator power. Lesions were unpredictable when uncontrolled generator power was applied. The created lesion shape was dependent on the selected electrode configuration. CONCLUSIONS: The currently available monopolar RFA systems offer different specific technical features to control tissue ablation. Detailed knowledge of the specific characteristics of each RF system is necessary to provide a higher chance of successful clinical outcome by complete and reliable ablation.

Animals↗

PubMed2005

Metallic stents for treatment of benign biliary obstruction: a long-term study comparing different stents.

PURPOSE: To investigate the role of metallic stents in the treatment of benign biliary strictures and analyze the differences in primary patency associated with the various types of stents deployed. MATERIALS AND METHODS: Between 1990 and 1997, 21 patients with benign obstructive jaundice were treated with transhepatic placement of metallic stents (11 Wallstents in 10 patients, nine Palmaz stents in seven patients, and four tantalum Strecker stents in four patients). Nineteen patients presented with strictures not responding to balloon angioplasty (postsurgical, n = 13; cholangitis, n = 5; unknown, n = 1). Estimates for cumulative patency, patency rate in the different stent groups, and survival were calculated with use of life-table analysis; the log-rank test was used to compare the different stent groups. The prognostic relevance of the selected variables-stent type, stent length, etiology, and location-were modeled with respect to patency according to Weibull distribution. RESULTS: The median follow-up time was 80.5 months (range, 2-116 months). The median survival time was 91 months. One patient was lost to follow-up after 3 months. Repeat intervention for recurrent obstructive jaundice was necessary in 11 patients (55%), and the median patency rate was 26 months (range, 2-96 months). The Palmaz stent was the most effective in achieving long-term patency, with a median patency duration of 36 months (range, 22-96 months), versus 9 months (range, 3-67 months) for the Wallstent and 6 months (range, 2-15 months) for the tantalum Strecker stent. The cumulative patency rate with the Palmaz stent was significantly higher than for the tantalum Strecker stent (log-rank test, P = .017) and nonsignificantly higher compared with the Wallstent (log-rank test, P = .07). Multivariate analysis showed that the type of stent (Wald test, P = .003) and stent length (Wald test, P < .0001) influenced the patency rate. CONCLUSIONS: These results suggest that the type of stent and the stent length have a significant influence on the patency rate. In this series, the Palmaz stent was most effective in achieving long-term patency in benign biliary strictures.

Adult↗

PubMed2004

Effects of vitamin K antagonist phenprocoumon on activated partial thromboplastin time measurement of direct thrombin inhibitors.

The activated partial thromboplastin time (aPTT) is currently the most common test used to measure the anticoagulation intensity of heparins and direct thrombin inhibitors (DTIs). Vitamin K antagonists variably affect aPTT reagents. Interactions between heparin and DTIs occur during concurrent therapy. Three DTIs (lepirudin, argatroban, melagatran) and one unfractionated heparin (liquemin) were added to normal plasma (NP) samples (n = 23) and to vitamin K antagonist plasma (VKAP) samples (n = 23) of patients treated with phenprocoumon. Lepirudin and argatroban were added at concentrations from 300 to 3000 ng/ml, melagatran from 30 to 1000 ng/ml, and unfractionated heparin from 0.016 to 0.48 IU/ml. Wave parameters of clotting time and aPTT ratio curves were evaluated by multivariate analysis for inhibitors, aPTT reagents and NP and VKAP samples. Normal ranges resulting from NP samples were 34.5 +/- 1.0 s with Pathromtin SL and 33.9 +/- 0.8 s with Platelin LS. Normal ranges using VKAP were 52.8 +/- 2.6 s (Pathromtin SL) and 44.2 +/- 1.1 s (Platelin LS) (P < 0.0001). Variance analysis showed that inhibitors, plasmas (NP versus VKAP) and reagents influenced the wave characteristics of aPTT (s) (P < 0.0001) and aPTT ratios (P < 0.0001). Distinct statistical differences between aPTT reagents on one hand and normal versus vitamin K antagonist plasma on the other hand make a comparison of reported aPTT results difficult, especially during overlapping therapy with vitamin K antagonists.

Anticoagulants↗