Papers by Siegfried Kropf
Biomarkers in medicine, 2018
To assess weather doctors' clinical risk-assessment for major adverse kidney events (MAKE) an... more To assess weather doctors' clinical risk-assessment for major adverse kidney events (MAKE) and acute kidney injury (AKI) after open-heart surgery would improve when being informed about neutrophil gelatinase-associated lipocalin (NGAL) test result at ICU admission. Clinical risk-assessment for MAKE and AKI were performed with and without providing NGAL test result and compared in an exploratory- and a validation-cohort using reclassification metrics, exemplary category-free net reclassification improvement (cfNRI). Exploratory cohort: doctors' prediction of MAKE (cfNRI = 0.750 [0.130-1.370]; p = 0.018) and AKI (cfNRI = 0.565 [0.001-1.129]; p = 0.049) improved being provided with NGAL test information. This finding was confirmed in the validation-cohort (MAKE cfNRI = 0.930 [0.188-1.672]; p = 0.014) and the combined-cohort (MAKE: cfNRI = 0.847 [0.371-1.323], p < 0.001); AKI: cfNRI = 0.468 [0.099-0.836; p = 0.013]). Improvements mostly generated from correctly reclassifying ...
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The lancet. Diabetes & endocrinology, Jan 31, 2018
Women with complete androgen insensitivity syndrome (CAIS) after gonadectomy have complained abou... more Women with complete androgen insensitivity syndrome (CAIS) after gonadectomy have complained about reduced psychological wellbeing and sexual satisfaction. The aim of this study was to compare the effectiveness of hormone-replacement therapy with either androgen or oestrogen in women with 46,XY karyotype and CAIS after gonadectomy. This national, multicentre, double-blind, randomised crossover trial was performed at three university medical centres and three specialised treatment institutions in Germany. Eligible participants were women aged 18-54 years with 46,XY karyotype, genetically diagnosed CAIS, and removed gonads. Participants were randomly assigned (14:12) by a central computer-based minimisation method to either oestradiol 1·5 mg/day for 6 months followed by crossover to testosterone 50 mg/day for 6 months (sequence A) or to testosterone 50 mg/day for 6 months followed by crossover to oestradiol 1·5 mg/day for 6 months (sequence B). Participants also received oestradiol or...
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International journal of cardiology, 2018
Right ventricular (RV) dysfunction is recognized as a cardinal prognostic marker in systolic hear... more Right ventricular (RV) dysfunction is recognized as a cardinal prognostic marker in systolic heart failure patients. Conflicting data exist on the interaction of RV function and left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT). This prospective monocentric trial was set up to assess the predictive value of baseline RV function and corresponding RV-pulmonary artery (PA) coupling on LV reverse remodeling after CRT. 110 patients with a CRT indication were prospectively enrolled. RV function and RV-PA interaction were analyzed at baseline using echocardiographic and invasive pressure-volume loop catheter approach. The primary endpoint was reverse LV remodeling (CRT-responder) defined as a reduction in LV end-systolic volume of ≥15% at 6 months. Responders had higher RV-PA coupling ratios (single-beat end-systolic elastance/PA elastance: Ees/Ea) at baseline, which corresponded to smaller RVs with better ejection fraction and lower afterload. After mu...
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Geburtshilfe und Frauenheilkunde, 2017
Worldwide the prevalence of neuropsychiatric illness among women of reproductive age is higher th... more Worldwide the prevalence of neuropsychiatric illness among women of reproductive age is higher than ever before. This study investigates the influences of maternal substance abuse/dependence and neuropsychiatric illness on pregnancy and neonatal outcomes. Using a retrospective study design 185 pregnancies in women with neuropsychiatric illnesses or substance abuse were identified at a single centre over a period of 3.25 years and compared to 4907 pregnancies in healthy women without mental illness. Differences in pre-, peri- and postnatal pregnancy parameters were studied. Numbers of previous abortions on obstetric history were significantly higher in cases compared to controls, women with depression being especially affected. The number of antenatal visits was also higher among cases, especially in women with depression. The caesarean section rate was significantly higher in cases compared to controls. Children of women with neuropsychiatric illness were born at lower gestational a...
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The Annals of Statistics
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Microbial biotechnology, Mar 1, 2017
A statistical method was developed to test for equivalence of microbial communities analysed by n... more A statistical method was developed to test for equivalence of microbial communities analysed by next-generation sequencing of amplicons. The test uses Bray-Curtis distances between the microbial community structures and is based on a two-sample jackknife procedure. This approach was applied to investigate putative effects of the antifungal biocontrol strain RU47 on fungal communities in three arable soils which were analysed by high-throughput ITS amplicon sequencing. Two contrasting workflows to produce abundance tables of operational taxonomic units from sequence data were applied. For both, the developed test indicated highly significant equivalence of the fungal communities with or without previous exposure to RU47 for all soil types, with reference to fungal community differences in conjunction with field site or cropping history. However, minor effects of RU47 on fungal communities were statistically significant using highly sensitive multivariate tests. Nearly all fungal taxa...
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Neuro-oncology, Jan 6, 2017
Skull base meningiomas are considered to be difficult for surgical treatment. We wondered whether... more Skull base meningiomas are considered to be difficult for surgical treatment. We wondered whether genetic alterations recently identified in benign non-NF2-mutated World Health Organization (WHO) grade I meningiomas are related to clinical features of skull base meningiomas and whether druggable signaling pathways are activated. We analyzed 93 skull base meningiomas (82 WHO grade I, 11 WHO grade II) for mutations of hot spots or the most relevant exons of AKT1, KLF4/TRAF7, SMO, PI3K, and the TERT promoter. The AKT1E17K mutation was present in 31% of patients and was related to meningothelial histology. AKT1E17K had a negative effect on the time to tumor recurrence. Analyses of activated signaling proteins revealed among AKT1E17K tumors a significantly higher rate of phospho-mammalian target of rapamycin (mTOR) and phospho-p70S6K+ tumors. AKT1E17K tumors with immunoexpression of phospho-extracellular signal-regulated kinase 1 or 2 (ERK1/2) were characterized by significantly shorter ...
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Muscle & nerve, Jan 4, 2017
We aimed to investigate whether sonographic peripheral cross-sectional nerve area (CSA) and progr... more We aimed to investigate whether sonographic peripheral cross-sectional nerve area (CSA) and progranulin (PGRN), a neuritic growth factor, are related to each other and whether they interact to predict clinical and paraclinical measures in amyotrophic lateral sclerosis (ALS). We included 55 ALS patients who had forearm median and ulnar nerve CSA, cerebrospinal fluid (CSF) PGRN and serum PGRN measures available. CSF PGRN was normalized against the CSF/serum albumin ratio (Qalb ). Using age, sex, height and weight adjusted general linear models we examined CSA x CSF PGRN interaction effects on various measures. There was a medium-effect size inverse relationship between CSA and CSF PGRN, but not between CSA and serum PGRN. Lower CSA values together with higher CSF PGRN levels were linked to smaller motor amplitudes. In ALS, the constellation of peripheral nerve atrophy together with higher CSF PGRN levels indicates pronounced axonal damage. This article is protected by copyright. All r...
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BMC cancer, Jan 29, 2017
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies today with an urge... more Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies today with an urgent need for novel therapeutic strategies. Biomarker analysis helps to better understand tumor biology and might emerge as a tool to develop personalized therapies. The aim of the study is to investigate four promising biomarkers to predict the clinical course and particularly the pattern of tumor recurrence after surgical resection. Patients undergoing surgery for PDAC can be enrolled into the PANCALYZE trial. Biomarker expression of CXCR4, SMAD4, SOX9 and IFIT3 will be prospectively assessed by immunohistochemistry and verified by rt.-PCR from tumor and adjacent healthy pancreatic tissue of surgical specimen. Immunohistochemistry expression pattern of all four biomarkers will be combined into a single score. Beginning with the hospital stay clinical data from enrolled patients will be collected and followed. Different adjuvant chemotherapy protocols will be used to create subgroups. The...
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Langenbeck's archives of surgery, Jan 21, 2017
Delayed gastric emptying (DGE) is a common functional disorder after esophagectomy with gastric t... more Delayed gastric emptying (DGE) is a common functional disorder after esophagectomy with gastric tube reconstruction. Little is known about risk factors that can predict this debilitating complication. Patients who underwent elective esophagectomy from 2008 to 2016 in a single center were retrospectively reviewed. Diagnosis of DGE was based on clinical, radiological, and endoscopic findings. Uni- and multivariate analyses were performed to identify patient-, tumor-, and procedure-related factors that increase the risk of DGE. One hundred eighty-two patients were included. Incidence of DGE was 39.0%. Overall, 27 (14.8%) needed an endoscopic intervention. Patients in the DGE group had a longer hospital stay (p < 0.01). No differences were found for the 30-day (p = 1.0) and hospital mortality (p = 1.0). On univariate analyses, a significant influence on DGE was demonstrated for pre-existing pulmonary comorbidity (p = 0.04), an anastomotic leak (p < 0.01), and postoperative pulmona...
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Molecular and Cellular Biochemistry, 2016
Sciatic nerve irritation is often associated with disturbed Ca(2+) homeostasis in related neurons... more Sciatic nerve irritation is often associated with disturbed Ca(2+) homeostasis in related neurons of the spinal cord. Since mitochondria substantially contribute to Ca(2+) homeostasis and little information is available, we studied the effects of loose sciatic nerve ligation, a chronic constriction injury (CCI), on neuronal mitochondria of the L3-L6 regions. Three groups of rats (untreated, sham operated, and ligated) were explored. For the characterization of mitochondria, specimens of the L3-L6 spinal cord regions were evaluated with respect to intracellular localization using pyruvate dehydrogenase immunohistochemistry and Mitotracker Red, and the ATP producing machinery by LC-MS/MS technique for the analysis of cardiolipin and high-resolution respirometry for the measurement of oxygen consumption. Therefore, the phospholipid cardiolipin supports electron transfer within the respiratory chain as part of mitochondrial respiration and is of high impact on the physical properties of the mitochondrial membrane system. Histological analysis of spinal cord motor neurons revealed clustering of mitochondria in ipsilateral samples from ligated animals 14 days after the insult. This phenomenon was similarly evident in the respective contralateral side. The intensity of MT-Red staining was enhanced exclusively at the ipsilateral side, indicating increased mitochondrial activity. CCI of the sciatic nerve caused massive changes in the composition of cardiolipin reflecting mitochondrial impairment in the early phase followed by regeneration processes as late response. Sciatic nerve CCI caused decrease in the capacity of mitochondrial ATP production that recovered within 14 days after treatment. In conclusion, we provide evidence that clustering of mitochondria, already verified for the spinal cord sensory neurons after CCI, also occurs in the respective motor neurons. Further we have demonstrated transient impairment of the capacity of mitochondrial ATP production in tissue samples. Stress-dependent changes in cardiolipin composition are sensitive markers and mediators of the response process including impairment and regeneration.
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Cardiovascular and interventional radiology, Jan 19, 2016
The aim of this study was to assess the rates of haemorrhagic and thrombotic complications in pat... more The aim of this study was to assess the rates of haemorrhagic and thrombotic complications in patients undergoing interventional tumour ablation with and without peri-interventional low-molecular-weight heparin (LMWH) thrombosis prophylaxis. Patients presented with primary and secondary neoplastic lesions in the liver, lung, kidney, lymph nodes and other locations. A total of 781 tumour ablations (radiofrequency ablation, n = 112; interstitial brachytherapy, n = 669) were performed in 446 patients over 22 months; 260 were conducted under peri-interventional thrombosis prophylaxis with LMWH (H-group;) and 521 without this (NH-group, in 143 of these, LMWH was given post-interventionally). Sixty-three bleeding events occurred. There were significantly more bleedings in the H-group than in the NH-group (all interventions, 11.66 and 6.26 %, p = 0.0127; liver ablations, 12.73 and 7.1 %, p = 0.0416). The rate of bleeding events Grade ≥ III in all procedures was greater by a factor of >2...
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PloS one, 2016
Vision loss after optic neuropathy is considered irreversible. Here, repetitive transorbital alte... more Vision loss after optic neuropathy is considered irreversible. Here, repetitive transorbital alternating current stimulation (rtACS) was applied in partially blind patients with the goal of activating their residual vision. We conducted a multicenter, prospective, randomized, double-blind, sham-controlled trial in an ambulatory setting with daily application of rtACS (n = 45) or sham-stimulation (n = 37) for 50 min for a duration of 10 week days. A volunteer sample of patients with optic nerve damage (mean age 59.1 yrs) was recruited. The primary outcome measure for efficacy was super-threshold visual fields with 48 hrs after the last treatment day and at 2-months follow-up. Secondary outcome measures were near-threshold visual fields, reaction time, visual acuity, and resting-state EEGs to assess changes in brain physiology. The rtACS-treated group had a mean improvement in visual field of 24.0% which was significantly greater than after sham-stimulation (2.5%). This improvement pe...
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ABSTRACT In this paper a new class of exact parametric tests for multivariate normal data based o... more ABSTRACT In this paper a new class of exact parametric tests for multivariate normal data based on the theory of spherical distributions (FANG and ZHANG, 1990) is proposed. These tests maintain the alpha level in each case. They are advantageous with respect to power when special restrictions such as factorial structures are given in the data. The scope of the new theory is very broad so that it can be adapted to many different situations. Especially, it allows an inclusion of data-preprocessing in the analysis without influencing the error of the first kind. Thus the approach presented in the paper provides a link between exploratory and confirmatory techniques. The method can be used successfully with high-dimensional samples of small sample size or with highly correlated variables. In such cases classical multivariate analysis would lead to very unstable results.
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European Radiology, Feb 1, 2000
The aim of this study was to evaluate the diagnostic potential of virtual endoscopy (VE) and to c... more The aim of this study was to evaluate the diagnostic potential of virtual endoscopy (VE) and to compare it with axial CT slices, multiplanar reconstructions (MPR), minimal intensity projections (mIP), and bronchoscopy in patients diagnosed with bronchogenic carcinoma. Thirty patients underwent a spiral CT. Axial CT images were transferred to an Onyx workstation (Silicon Graphics, Sun Microsystems, Mountain View, Calif.) for performing virtual endoscopy. Accuracy for this procedure was tested by three radiologists on a monitor in comparison with axial CT slices, MPR, mIP, and bronchoscopy concerning the localization and degree of stenoses. Endoluminal tumors were identified by virtual bronchoscopy with no statistically significant difference of localization or grading of stenosis in comparison with bronchoscopy, axial CT slices, MPR and mIP. Axial CT slices, MPR, and mIP showed poorer results with over- or underestimation of stenoses compared with VE and bronchoscopy. Passing of stenoses was only possible with VE in 5 patients. Virtual endoscopy is a non-invasive method for identification of endoluminal tumors and is comparable to real bronchoscopy.
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Fems Microbiology Ecology, 2008
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Clin Chem Lab Med, 2008
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Oncogene, 2004
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Geburtsh Frauenheilk, 2009
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Papers by Siegfried Kropf