Assessment and Risk Prediction of Chronic Kidney Disease and Kidney Fibrosis Using Non-Invasive Biomarkers

Effective management of chronic kidney disease (CKD), a major health problem worldwide, requires accurate and timely diagnosis, prognosis of progression, assessment of therapeutic efficacy, and, ideally, prediction of drug response. Multiple biomarkers and algorithms for evaluating specific aspects of CKD have been proposed in the literature, many of which are based on a small number of samples. Based on the evidence presented in relevant studies, a comprehensive overview of the different biomarkers applicable for clinical implementation is lacking. This review aims to compile information on the non-invasive diagnostic, prognostic, and predictive biomarkers currently available for the management of CKD and provide guidance on the application of these biomarkers. We specifically focus on biomarkers that have demonstrated added value in prospective studies or those based on prospectively collected samples including at least 100 subjects. Published data demonstrate that several valid non-invasive biomarkers of potential value in the management of CKD are currently available.

Differentiating primary and secondary FSGS using non-invasive urine biomarkers

Background

Focal segmental glomerulosclerosis (FSGS) is divided into genetic, primary (p), uncertain cause, and secondary (s) forms. The subclasses differ in management and prognosis with differentiation often being challenging. We aimed to identify specific urine proteins/peptides discriminating between clinical and biopsy-proven pFSGS and sFSGS.

Methods

Sixty-three urine samples were collected in two different centers (19 pFSGS and 44 sFSGS) prior to biopsy. Samples were analysed using capillary electrophoresis-coupled mass spectrometry. For biomarker definition, datasets of age-/sex-matched normal controls (NC, n = 98) and patients with other chronic kidney diseases (CKDs, n = 100) were extracted from the urinary proteome database. Independent specificity assessment was performed in additional data of NC (n = 110) and CKD (n = 170).

Results

Proteomics data from patients with pFSGS were first compared to NC (n = 98). This resulted in 1179 biomarker (P < 0.05) candidates. Then, the pFSGS group was compared to sFSGS, and in a third step, pFSGS data were compared to data from different CKD etiologies (n = 100). Finally, 93 biomarkers were identified and combined in a classifier, pFSGS93. Total cross-validation of this classifier resulted in an area under the receiving operating curve of 0.95. The specificity investigated in an independent set of NC and CKD of other etiologies was 99.1% for NC and 94.7% for CKD, respectively. The defined biomarkers are largely fragments of different collagens (49%).

Conclusion

A urine peptide-based classifier that selectively detects pFSGS could be developed. Specificity of 95%-99% could be assessed in independent samples. Sensitivity must be confirmed in independent cohorts before routine clinical application.

TRAUMATIC PULMONARY HERNIATION: A RARE CHEST TRAUMA MANIFESTATION

Traumatic pulmonary hernia is an uncommon occurrence resulting from chest trauma, typically covered by the skin. Chest trauma may arise from penetrating or blunt mechanisms, with blunt trauma being more frequently observed. When lung herniation transpires, various symptoms such as chest pain, dyspnea, subcutaneous emphysema, bone crepitation, and hemoptysis (in cases of lung parenchymal damage) may manifest. We present the case of a 66-year-old woman suffering from chest pain and dyspnea after blunt chest trauma due to a fall induced by delirium following alcohol abuse.

Microangiopathy in multiple myeloma: a case of carfilzomib-induced secondary thrombotic microangiopathy successfully treated with plasma exchange and complement inhibition

BACKGROUND

Thrombotic microangiopathy (TMA) is a potentially organ and life-threatening condition affecting patients with multiple myeloma (MM). Cases of proteasome inhibitor-induced TMA and specifically carfilzomib-induced TMA have been rarely reported and standards for diagnostic workup and treatment are not available.

CASE PRESENTATION

We describe a case of a male MM patient under salvage therapy including proteasome inhibitor carfilzomib following chemotherapy and autologous stem cell transplantation. The patient then developed acute kidney injury with clinical and laboratory signs of TMA. Hemodialysis became necessary and treatment with plasma exchange was initiated followed by therapy with C5 complement inhibitor eculizumab which led to amelioration of kidney function and hemolysis parameters.

CONCLUSION

We report a patient with suspected proteasome inhibitor-induced secondary thrombotic microangiopathy that has been successfully treated with plasma exchange and eculizumab, a monoclonal antibody targeting complement factor C5.

Recent Advances in Urinary Peptide and Proteomic Biomarkers in Chronic Kidney Disease: A Systematic Review

Biomarker development, improvement, and clinical implementation in the context of kidney disease have been a central focus of biomedical research for decades. To this point, only serum creatinine and urinary albumin excretion are well-accepted biomarkers in kidney disease. With their known blind spot in the early stages of kidney impairment and their diagnostic limitations, there is a need for better and more specific biomarkers. With the rise in large-scale analyses of the thousands of peptides in serum or urine samples using mass spectrometry techniques, hopes for biomarker development are high. Advances in proteomic research have led to the discovery of an increasing amount of potential proteomic biomarkers and the identification of candidate biomarkers for clinical implementation in the context of kidney disease management. In this review that strictly follows the PRISMA guidelines, we focus on urinary peptide and especially peptidomic biomarkers emerging from recent research and underline the role of those with the highest potential for clinical implementation. The Web of Science database (all databases) was searched on 17 October 2022, using the search terms "marker *" OR biomarker * AND "renal disease" OR "kidney disease" AND "proteome *" OR "peptid *" AND "urin *". English, full-text, original articles on humans published within the last 5 years were included, which had been cited at least five times per year. Studies based on animal models, renal transplant studies, metabolite studies, studies on miRNA, and studies on exosomal vesicles were excluded, focusing on urinary peptide biomarkers. The described search led to the identification of 3668 articles and the application of inclusion and exclusion criteria, as well as abstract and consecutive full-text analyses of three independent authors to reach a final number of 62 studies for this manuscript. The 62 manuscripts encompassed eight established single peptide biomarkers and several proteomic classifiers, including CKD273 and IgAN237. This review provides a summary of the recent evidence on single peptide urinary biomarkers in CKD, while emphasizing the increasing role of proteomic biomarker research with new research on established and new proteomic biomarkers. Lessons learned from the last 5 years in this review might encourage future studies, hopefully resulting in the routine clinical applicability of new biomarkers.

MO386: Visualising and Differentiating Kidney Disorders by Urinary Peptidomics Using a Machine Learning Approach

BACKGROUND AND AIMS

Currently &gt;20 000 native peptides in urine are known that are highly dynamic and able to display the status of different organs, especially the kidney. The characterization of urinary peptide profiles (UPP) enables the depiction of kidney disease severity, progression, fibrosis, and informs about the disease etiology. Advanced machine learning algorithms enable combining the changes in the very complex UPP associated with specific disease etiologies and reducing the dataspace to only few dimensions. Here, we show the application of a supervised machine learning pipeline for the visualization of different CKD etiologies based on high-dimensional peptidomics data, toward non-invasive disease classification.

METHOD

The Uniform Manifold Approximation and Projection (UMAP) algorithm was used as a novel nonlinear dimensionality-reduction technique to visualize and differentiate the UPP of patients with CKD of different etiologies. UPP of individual CKD patients (with diabetic kidney disease DKD, (n = 386), IgA nephropathy (n = 743) and vasculitis (n = 150)) and 369 healthy controls were extracted from the Human Urinary Proteome Database which contains &gt;85 000 proteomics datasets analyzed using capillary electrophoresis coupled mass spectrometry. About 80% of the extracted datasets were used as a training and 20% as validation set.

RESULTS

When applying supervised-UMAP to the DKD patient and control datasets, excellent separation with an F1 score of 99.5% ± 0.9% in the training set, and 93.1% ± 3.3% in the independent test set could be observed. Subsequently, this approach was applied to differentiate controls and three kidney diseases (DKD, IgA nephropathy and vasculitis) simultaneously. In the training set an accuracy of up to 98% in DN and controls, and an overall F1 score of 93.7% ± 2.3% (Figure) was achieved. In the independent test set, accuracy decreased as expected to around 90% for controls, 83.8% for IgA nephropathy, 79.2% for DKD and 66.7% for vasculitis. The overall F1 score in the test set is 81.9% ± 2.2%. Of note, controls (n = 369) were consistently classified with the highest accuracy across all groups, the disease with smallest sample size (vasculitis, n = 150) always showed the lowest accuracy. A substantial proportion of vasculitis was classified as IgA nephropathy, which has the largest sample size of n = 743.

For the validation of the pipeline the permutation test was used. Permutation test was repeated 100 times using all the samples of CKD -free controls and three kidney diseases. The resulted scores were normally distributed, with a mean of 32.5% and standard deviation of 1.2%. Compared with the true F1 score, which was calculated as 81.9% from above, the probability of obtaining such a high score by chance is very low (P &lt; 0.01).

CONCLUSION

We show that UMAP combined with supervised machine learning applied to high dimensional peptidomics data, enables distinguishing multiple kidney diseases with good accuracy and with very small standard deviation between multiple train-test splits. To our knowledge, our study is the first of its kind to reduce the complexity of the urinary peptidome to a single point in space, and categorize disease etiology based on the spatial information. The approach presented has the potential to enable non-invasive differential diagnosis of kidney disease etiologies. To improve accuracy of this non-invasive method, inclusion of additional clinical parameters will be tested.

Molecular Mapping of Urinary Complement Peptides in Kidney Diseases

Defective complement activation has been associated with various types of kidney disease. This led to the hypothesis that specific urine complement fragments may be associated with kidney disease etiologies, and disease progression may be reflected by changes in these complement fragments. We investigated the occurrence of complement fragments in urine, their association with kidney function and disease etiology in 16,027 subjects, using mass spectrometry based peptidomics data from the Human Urinary Proteome/Peptidome Database. Twenty-three different urinary peptides originating from complement proteins C3, C4 and factor B (CFB) could be identified. Most C3-derived peptides showed inverse association with estimated glomerular filtration rate (eGFR), while the majority of peptides derived from CFB demonstrated positive association with eGFR. Several peptides derived from the complement proteins C3, C4 and CFB were found significantly associated with specific kidney disease etiologies. These peptides may depict disease-specific complement activation and could serve as non-invasive biomarkers to support development of complement interventions through assessing complement activity for patients’ stratification and monitoring of drug impact. Further investigation of these complement peptides may provide additional insight into disease pathophysiology and could possibly guide therapeutic decisions, especially when targeting complement factors.

A Novel Urinary Proteomics Classifier for Non-Invasive Evaluation of Interstitial Fibrosis and Tubular Atrophy in Chronic Kidney Disease

Non-invasive urinary peptide biomarkers are able to detect and predict chronic kidney disease (CKD). Moreover, specific urinary peptides enable discrimination of different CKD etiologies and offer an interesting alternative to invasive kidney biopsy, which cannot always be performed. The aim of this study was to define a urinary peptide classifier using mass spectrometry technology to predict the degree of renal interstitial fibrosis and tubular atrophy (IFTA) in CKD patients. The urinary peptide profiles of 435 patients enrolled in this study were analyzed using capillary electrophoresis coupled with mass spectrometry (CE-MS). Urine samples were collected on the day of the diagnostic kidney biopsy. The proteomics data were divided into a training (n = 200) and a test (n = 235) cohort. The fibrosis group was defined as IFTA ≥ 15% and no fibrosis as IFTA < 10%. Statistical comparison of the mass spectrometry data enabled identification of 29 urinary peptides with differential occurrence in samples with and without fibrosis. Several collagen fragments and peptide fragments of fetuin-A and others were combined into a peptidomic classifier. The classifier separated fibrosis from non-fibrosis patients in an independent test set (n = 186) with area under the curve (AUC) of 0.84 (95% CI: 0.779 to 0.889). A significant correlation of IFTA and FPP_BH29 scores could be observed Rho = 0.5, p < 0.0001. We identified a peptidomic classifier for renal fibrosis containing 29 peptide fragments corresponding to 13 different proteins. Urinary proteomics analysis can serve as a non-invasive tool to evaluate the degree of renal fibrosis, in contrast to kidney biopsy, which allows repeated measurements during the disease course.

Adverse Drug Events in Patients with Chronic Kidney Disease Associated with Multiple Drug Interactions and Polypharmacy

BACKGROUND AND PURPOSE

Chronic kidney disease (CKD) is associated with adverse drug events due to medication errors and the risks of polypharmacy. The aim of this study was to investigate whether multiple pharmacodynamic interactions are a significant problem in CKD patients to improve medication safety.

METHODS

The discharge medication of 200 elderly patients with stage 3, 4 and 5/5D CKD was analysed in a retrospective observational study with respect to kidney-related medication errors and multiple pharmacodynamic interactions. The clinical relevance of the most common and hazardous multiple interactions was assessed by evaluating adverse events at the primary or the subsequent hospital stay.

RESULTS

Findings showed that 29.5% of the study cohort were at risk of QTc-interval prolongation in association with their medication combinations and half of them exhibited QTc-interval prolongation. The QTc interval was extended among all patients receiving a combination of two or more drugs with 'known' risk of Torsades de pointes. Amiodarone, citalopram and ciprofloxacin turned out to be the most hazardous drugs in this context. Eight percent of the patient population received a regimen of 4-6 potassium-enhancing drugs during their hospital stay, which was not de-escalated in 75.0% in the ambulatory setting. Despite close monitoring in the clinical setting, 37.5% of these patients developed hyperkalaemic episodes during their primary stay and 66.7% during rehospitalization. Of the study cohort, 8.5% received a combination of three drugs with antithrombotic or antiplatelet effects. Of these, 64.7% developed haemorrhagic events with two of them proving fatal.

CONCLUSION

Multiple pharmacodynamic interactions related to QTc prolongation, hyperkalaemia and haemorrhage are frequently associated with a negative outcome in older adults with CKD and often require recurrent medical treatment or rehospitalization.

Noninvasive diagnosis of chronic kidney diseases using urinary proteome analysis

Background

In spite of its invasive nature and risks, kidney biopsy is currently required for precise diagnosis of many chronic kidney diseases (CKDs). Here, we explored the hypothesis that analysis of the urinary proteome can discriminate different types of CKD irrespective of the underlying mechanism of disease.

Methods

We used data from the proteome analyses of 1180 urine samples from patients with different types of CKD, generated by capillary electrophoresis coupled to mass spectrometry. A set of 706 samples served as the discovery cohort, and 474 samples were used for independent validation. For each CKD type, peptide biomarkers were defined using statistical analysis adjusted for multiple testing. Potential biomarkers of statistical significance were combined in support vector machine (SVM)-based classifiers.

Results

For seven different types of CKD, several potential urinary biomarker peptides (ranging from 116 to 619 peptides) were defined and combined into SVM-based classifiers specific for each CKD. These classifiers were validated in an independent cohort and showed good to excellent accuracy for discrimination of one CKD type from the others (area under the receiver operating characteristic curve ranged from 0.77 to 0.95). Sequence analysis of the biomarkers provided further information that may clarify the underlying pathophysiology.

Conclusions

Our data indicate that urinary proteome analysis has the potential to identify various types of CKD defined by pathological assessment of renal biopsies and current clinical practice in general. Moreover, these approaches may provide information to model molecular changes per CKD.

[Severe thoracic bleeding - 25 years after nephrectomy]

We report a case of a 62 year old patient, who was hospitalised due to haemorrhagic shock. The cause was a rupture of the pulmonary artery due to metastasis of a renal cell carcinoma. This cause is now reported for the first time. The primary tumour (pT2,pN0,M0,R0) was resected 25 years ago. This case demonstrates that after curative nephrectomy pulmonary metastasis can occur, even after decades. This is why patients of this type need lifelong follow-up.

Tc-99m DTPA Perfusion Scintigraphy and Color Coded Duplex Sonography in the Evaluation of Minimal Renal Allograft Perfusion

Aim: The clinical impact of perfusion scintigraphy versus color coded Duplex sonography was evaluated, with respect to their potential in assessing minimal allograft perfusion in vitally threatened kidney transplants, i.e. oligoanuric allografts suspected to have either severe rejection or thrombosis of the renal vein or artery. Methods: From July 1990 to August 1994 the grafts of 15 out of a total of 315 patients were vitally threatened. Technetium-99m DTPA scintigraphy and color coded Duplex sonography were performed in all patients. For scintigraphic evaluation of transplant perfusion analog scans up to 60 min postinjection, and time-activity curves over the first 60 sec after injection of 370-440 MBq Tc-99m diethylenetriaminepentaacetate acid (DTPA) were used and classified by a perfusion score, the time between renal and iliac artery peaks (TDiff) and the washout of the renogram curve. Additionally, evaluation of excretion function and assessment of vascular or urinary leaks were performed. By color coded Duplex sonography the perfusion in all sections of the graft as well as the vascular anastomoses were examined and the maximal blood flow velocity (Vmax) and the resistive index (Rl) in the renal artery were determined by means of the pulsed Doppler device. Pathologic-anatomical diagnosis was achieved by either biopsy or post-explant histology in all grafts. Results: Scintigraphy and color coded Duplex sonography could reliably differentiate minimal (8/15) and not perfused (7/15) renal allografts. The results were confirmed either by angiography in digital subtraction technique (DSA) or the clinical follow up. Conclusion: In summary, perfusion scintigraphy and color coded Duplex sonography are comparable modalities to assess kidney graft perfusion. In clinical practice scintigraphy and color-coded Doppler sonography can replace digital subtraction angiography in the evaluation of minimal allograft perfusion.

[Severe Hemorrhagic Shock in a 93-Year Old Patient due to a Diagnostic Thoracocentesis]

An intercostal artery laceration is a rare iatrogenic complication following thoracocentesis and concerns especially elderly patients. We report a case of a severe hemorrhagic shock in a 93-year old patient due to diagnostic thoracocentesis.

Homocysteine concentration in coronary artery disease: Influence of three common single nucleotide polymorphisms

BACKGROUND AND AIMS

Whether single nucleotide polymorphisms (SNPs) of homocysteine metabolism enzymes influence the rate of cardiovascular (CV) events in coronary artery disease (CAD) patients remains controversial.

METHODS AND RESULTS

In this analysis, 1126 subjects from the AtheroGene study with CAD and 332 control subjects without known CAD were included. The following SNPs were investigated: methylentetrahydrofolate reductase (MTHFR-C667T), methionin synthetase (MS-D919G), and cystathionin beta synthetase (CBS-I278T). The endpoint was the combination of cardiovascular death, stroke, and non-fatal myocardial infarction (N = 286). The median follow-up time was 6.4 years. Kaplan-Meier curve analysis showed an increasing event rate with rising homocysteine levels (p < 0.001) in CAD patients. Further, in Cox-Regression analysis homocysteine was a predictor of the endpoint with a hazard ratio (HR) of 6.5 (95% CI: 2.9-14.6, p < 0.001) in the adjusted model including cardiovascular risk factors. Of the three SNPs, homozygous MTHFR SNP increased homocysteine levels significantly in patients with CAD and individuals without CAD (both p < 0.001). The SNPs in MS and CBS were not related to relevant changes in homocysteine levels in CAD patients or controls. The different SNPs of MTHFR, MS, and CBS were not related to an increased event rate.

CONCLUSION

Homocysteine level is a strong predictor of CV events. Subjects with and without CAD and SNPs in the enzyme MTHFR had increased homocysteine levels. This was not observed for MS and CBS SNPs. Although MTHFR SNPs alter homocysteine levels in patients and controls, these polymorphisms had no impact on prognosis in CAD patients.

Zum Einfluß von Inhomogenitäten mit Schichtstruktur auf die galvanomagnetischen Effekte

Es wird gezeigt, daß durch eine Überstruktur der Störstellenverteilung in Form von Schichten die galvanomagnetischen Effekte in empfindlicher Weise gestört werden können. Dies kann sich in einer ausgeprägten Anisotropie der Widerstandsänderung äußern, welche durch die Überlagerung einer hohen geometriebedingten Widerstandsänderung hervorgerufen wird. Aus der Abhängigkeit dieser geometrischen Widerstandsänderung vom Winkel zwischen Magnetfeld und Probenlängsachse läßt sich auf die Lage der Schichtstruktur relativ zum Probensystem schließen. Man erhält den unverfälschten Wert der physikalischen Widerstandsänderung nur dann, wenn die Normale der Schichtstruktur senkrecht auf der Probenlängsachse steht. Im Gegensatz zur Widerstandsänderung erweist sich der in B lineare HALL-Effekt unabhängig von der relativen Lage der Schichtstruktur. Man mißt stets den gleichen Mittelwert des HALL-Koeffizienten.

Bei der Messung des planaren HALL-Effektes macht sich die Überstruktur der Störstellenverteilung wiederum störend bemerkbar. Für die Extremlagen, Schichtnormale parallel und senkrecht zur Probenlängsachse, findet man den wahren planaren HALL-Effekt. Jedoch bereits kleine Abweichungen von diesen beiden Idealfällen (10° —15°) führen zu einer starken Verfälschung der Winkelabhängigkeit. Da diese Extremfälle experimentell nur schwer zu realisieren sind, kann der Bestimmung der Widerstandsänderung aus Messungen des planaren HALL-Effektes, wie sie in einer früheren Arbeit2 vorgenommen wurde, nur qualitative Bedeutung zukommen. Unter den dort gemachten Einschränkungen aber stellt die Messung des planaren HALL-Effekts zweifelsohne ein weiteres Hilfsmittel dar, eine Entscheidung über die Größenordnung der wahren Widerstandsänderung zu treffen.

Über die galvanomagnetischen Eigenschaften von InSb-Einkristallen mit Te-Dotierung

An InSb-Einkristallen mit einem Te-Gehalt größer 2·1016/cm3 wurde die Änderung des elektrischen Widerstandes im Magnetfeld in Abhängigkeit von Dotierung, magnetischer Induktion und Winkel zwischen Strom und magnetischer Induktion bei Zimmertemperatur, 78°K und 4,2°K gemessen. Es ergab sich eine scheinbare Anisotropie derart, daß die Werte der transversalen Widerstandsänderung mit Probenstrom parallel zur Wachstumsrichtung [111] immer größer waren, als wenn der Strom senkrecht zur Wachstumsrichtung floß. Die Unterschiede betrugen bis zu 2 Größenordnungen. Aus den Messungen des planaren HALL-Effektes folgt, daß in n-leitendem InSb bei Zimmertemperatur die Widerstandsänderung fast ausschließlich durch die gemischte Leitung verursacht wird. Dieser überlagert sich eine durch die Präparation bedingte Anisotropie.

Im Gegensatz zur Widerstandsänderung ist die Elektronenbeweglichkeit isotrop. Der HALL-Koeffizient ist im Bereich zwischen 100 Gauß und 10 kGauß innerhalb der Fehlergrenze von einigen Promillen konstant.

Zur Deutung der Anisotropie der Widerstandsänderung von n-leitendem InSb

Kristalle aus InSb, welche nach der Czochralski-Methode hergestellt sind und einen Te-Gehalt größer als 10166 cm-3 besitzen, zeigen häufig eine Anisotropie der Widerstandsänderung. Bei Proben mit einer Stromrichtung I parallel zur Wachstumsrichtung ist die Widerstandsänderung über eine Größenordnung höher als bei Proben mit I senkrecht zur Wachstumsrichtung. Dieses Verhalten wurde für die Wachstumsrichtungen [1.11], [100] und [113] festgestellt. Durch geeignete Wahl der Ziehgeschwindigkeit läßt sich diese Anisotropie vollständig beseitigen. Die Ergebnisse können durch Annahme eines schichtweisen Einbaus der Störstellen in Schichten wechselnder Konzentration senkrecht zur Wachstumsrichtung erklärt werden. Die experimentellen Resultate stehen in Übereinklang mit einer von HERRING entwickelten Theorie.

[Results of preclinically placed thoracic drainages]

BACKGROUND

Thorax injuries are to be found in approximately 78 % amongst all victims of accidents. Moreover they implicate an increase in mortality rate. Consequently an adequate contemporary treatment has to begin preclinically, even if the conditions are less comfortable than in a clinical setting. Emergency doctors need to be familiar with the placement of chest tubes.

METHODS

From 01.01.2007 to 31.12.2010 emergency doctors of the rescue helicopter site Christoph 20 had to place chest tubes directly at the scene of an accident in 49 patients. These patients were now reidentified and their clinical course reevaluated. By means of apparative diagnostics it was possible to analyse the location of the tips of the tubes. A comparison of the patient outcome versus the quality of preclinical thoracic drainage could be made.

RESULTS

The preclinical placement of a chest tube became necessary mainly because of a blunt thoracic trauma. This was predominantly related to victims of traffic accidents, whereas male victims clearly dominated. 42 of those patients received further treatment at the Klinikum Bayreuth, enabling an analysis of the tube locations by CT scans. Six patients had been drained on both sides, contributing to the 48 tube tips that could be examined concerning their location. Of the 48 chest tubes 46 had been placed from a lateral approach. The ventral access according to Monaldi had only been chosen in two cases. Altogether nine incorrect placements, mainly within the right interlobe gap, were detected.

CONCLUSION

The study collective showed a significant preference to the lateral approach when placing a chest tube at the emergency scene of an accident. In total a prevalence of 19 % incorrect placements could be revealed, meaning the chest tube had either been placed within the lung parenchyma, the interlobe gap or extrathoracically. Concerning the patient outcome no statistically significant difference regarding the clinical course after incorrect chest tube placement could be identified. The omission of an indicated preclinical thoracic drainge is certainly a more serious error than its incorrect placement with more serious consequences.

Ruptured pulmonary artery aneurysm mimicking pulmonary embolism

Aneurysms of the pulmonary artery are very rare pathological vascular conditions. Peripheral pulmonary aneurysms have been reported only in a few cases. The causes of these aneurysms include extensive degenerative changes, traumas, infection and congenital malformations. Because of the imminent danger of rupture, surgical treatment should always be preferred. The following case report demonstrates one of a multitude of possible misdiagnoses for rupture of a pulmonary aneurysm.

Naturally occurring human urinary peptides for use in diagnosis of chronic kidney disease

Because of its availability, ease of collection, and correlation with physiology and pathology, urine is an attractive source for clinical proteomics/peptidomics. However, the lack of comparable data sets from large cohorts has greatly hindered the development of clinical proteomics. Here, we report the establishment of a reproducible, high resolution method for peptidome analysis of naturally occurring human urinary peptides and proteins, ranging from 800 to 17,000 Da, using samples from 3,600 individuals analyzed by capillary electrophoresis coupled to MS. All processed data were deposited in an Structured Query Language (SQL) database. This database currently contains 5,010 relevant unique urinary peptides that serve as a pool of potential classifiers for diagnosis and monitoring of various diseases. As an example, by using this source of information, we were able to define urinary peptide biomarkers for chronic kidney diseases, allowing diagnosis of these diseases with high accuracy. Application of the chronic kidney disease-specific biomarker set to an independent test cohort in the subsequent replication phase resulted in 85.5% sensitivity and 100% specificity. These results indicate the potential usefulness of capillary electrophoresis coupled to MS for clinical applications in the analysis of naturally occurring urinary peptides.

Identification and validation of urinary biomarkers for differential diagnosis and evaluation of therapeutic intervention in anti-neutrophil cytoplasmic antibody-associated vasculitis

Renal activity and smoldering disease is difficult to assess in anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) because of renal scarring. Even repeated biopsies suffer from sampling errors in this focal disease especially in patients with chronic renal insufficiency. We applied capillary electrophoresis coupled to mass spectrometry toward urine samples from patients with active renal AAV to identify and validate urinary biomarkers that enable differential diagnosis of disease and assessment of disease activity. The data were compared with healthy individuals, patients with other renal and non-renal diseases, and patients with AAV in remission. 113 potential biomarkers were identified that differed significantly between active renal AAV and healthy individuals and patients with other chronic renal diseases. Of these, 58 could be sequenced. Sensitivity and specificity of models based on 18 sequenced biomarkers were validated using blinded urine samples of 40 patients with different renal diseases. Discrimination of AAV from other renal diseases in blinded samples was possible with 90% sensitivity and 86.7-90% specificity depending on the model. 10 patients with active AAV were followed for 6 months after initiation of treatment. Immunosuppressive therapy led to a change of the proteome toward "remission." 47 biomarkers could be sequenced that underwent significant changes during therapy together with regression of clinical symptoms, normalization of C-reactive protein, and improvement of renal function. Proteomics analysis with capillary electrophoresis-MS represents a promising tool for fast identification of patients with active AAV, indication of renal relapses, and monitoring for ongoing active renal disease and remission without renal biopsy.

Angiopoietin 1 and 2 gene and protein expression is differentially regulated in acute anti-Thy1.1 glomerulonephritis

Capillary neoformation is important in repair of glomerular injury of various origins. VEGF was shown to be crucial for glomerular capillary repair in glomerulonephritis (GN). We reasoned that other angiogenic factors are likewise involved in glomerular capillary remodeling and found angiopoietin 1 and -2 (ANG1 and ANG2) mRNA to be upregulated in cDNA microarrays of microdissected glomeruli of anti-Thy1.1 GN of the rat. We then studied glomerular in situ gene and protein expression of ANG1 and ANG2 and their receptor Tie-2 in the course of anti-Thy1.1 GN, which was induced by injection of OX-7 antibody. Animals were perfusion fixed at days 6 and 12 after GN induction and compared with nonnephritic controls receiving PBS. Capillary damage and repair were quantitatively analyzed using stereological techniques. Gene and protein expression of ANG1 and ANG2 and their receptor Tie-2 was analyzed using real-time quantitative PCR from microdissected glomeruli, nonradioactive in situ hybridization, double immunofluorescence, and Western blot analysis. Glomerular capillarization assessed as length density was significantly lower at day 6 of anti-Thy1.1 GN than in controls; it was back to normal values at day 12. ANG1 and ANG2 gene expression was markedly upregulated at day 6 of the disease compared with controls. Protein expression of ANG1 and ANG2 was confined to podocytes and that of Tie-2 to endothelial cells. At day 12 of anti-Thy1.1 GN when capillary restoration was nearly completed, ANG1 and ANG2 gene expression returned to basal levels, whereas Tie-2 expression was still high. With the use of a combined molecular and in situ approach, the spatial and temporal gene and protein expression of the angiopoietins and their receptor was analyzed in anti-Thy1.1 GN. The results indicate that glomerular expression of ANG1 and ANG2 and Tie-2 is differentially regulated and may contribute to healing and endothelial cell stabilization in experimental GN.

Postinterventionelles Cholesterinemboliesyndrom

HISTORY AND ADMISSION FINDINGS

A 73-year old woman was admitted to the hospital because of progressive renal failure with onset 2 months after an angiogram of the legs. She had diabetes mellitus and was hypertensive. Her feet were cold, painful and showed irregular blue and purple discolorations.

INVESTIGATIONS

Blood pressure was 170/80 mmHg, heart rate 72 bpm. Serum creatinine was 6,7 mg/dl (eGFR 7 ml/min) and she had proteinuria of 4,3 g/l. The erythrocyte sedimentation rate was markedly elevated, she had eosinophilia and hypocomplementemia.

DIAGNOSIS AND THERAPY

Because of the acute renal failure and proteinuria a renal biopsy was taken, as well as a skin biopsy from the patients foot. Both biopsies showed cholesterol crystal emboli with elongated, biconvex transparent clefts and an inflammatory reaction of the vessel wall which had caused obstruction. Renal function did not recover, and the patient was transferred to the chronic dialysis program. Treatment with a statin was initiated and her blood pressure normalized.

CONCLUSION

In most cases cholesterol crystal embolism is iatrogenic. This multiorgan syndrome occurs in patients at high risk of cardiovascular disease. Cholesterol crystals from ruptured atheromatous plaques become lodged in peripheral arteries and induce an obliterating inflammation of the vessel wall. Mortality is high (about 38 %).

Nitric oxide modulates expression of extracellular matrix genes linked to fibrosis in kidney mesangial cells

Mesangial cells are thought to be important mediators of glomerular inflammation and fibrosis. Studies have established a direct role for nitric oxide (NO) in the regulation of gene expression in mesangial cells. Representational difference analysis was used to investigate changes in gene expression elicited by the treatment of S-nitroso-L-glutathione in rat mesangial cells. Seven upregulated and 11 downregulated genes were identified. Four out of 11 downregulated genes (connective tissue growth factor, thrombospondin-1, collagen type I alpha1 and collagen type I alpha2) are known to be linked to inflammation and fibrosis. Results were verified across species in mesangial cells treated with a series of NO donors using Northern blot analysis, quantitative real-time PCR and protein analysis methods. Induction of endogenous NO production by cytokine stimulation also triggered regulation of the genes. One example gene, connective tissue growth factor, was studied at the promoter level. Promoter-reporter gene studies in mesangial cells demonstrated that NO acts at the transcriptional level to suppress gene expression. Our results reveal a complex role of NO in regulating gene expression in mesangial cells and suggest an antifibrotic potential for NO.

Functional magnetic resonance imaging in renal artery stenosis

Renal artery stenosis (RAS) is the leading cause of secondary hypertension. Magnetic resonance (MR) imaging and in particular MR angiography have evolved into important diagnostic tools for the detection and grading of RAS due to the lack of ionizing radiation and nephrotoxic contrast agent. This review describes state-of-the-art MR angiographic techniques and introduces the reader to current concepts of RAS grading with MR angiography. We compare MR angiography with conventional angiography and intravascular ultrasound as a standard of reference. The technical basis of functional imaging techniques such as arterial spin labeling perfusion measurements, contrast-enhanced perfusion measurements, and MR flow measurements are explained. Their value for the grading and detection of RAS and for the differentiation of renovascular from renal parenchymal disease is discussed. An overview about imaging during and after interventional therapy of RAS and an introduction to the current understanding of prediction of successful interventional therapy finishes this review.