Entwicklung eines Zellkulturmodells zur metachromatischen Leukodystrophie durch Transduktion glialer Zellen mit lentiviralen Vektoren

Die metachromatische Leukodystrophie ist eine autosomal-rezessiv vererbte, lysosomale Speicherkrankheit mit schwerwiegendem Verlust erlernter Fähigkeiten und infauster Prognose. Die Erkrankung ist unaufhaltsam progredient, die Patienten versterben im Stadium der Dezerebration. Ihr liegt zumeist eine Defizienz der Arylsulfatase A zugrunde, welche ein Schlüsselenzym im Abbau der 3,0-Sulfogalactosyl-Glykolipide, insbesondere des Sulfatids, ist. Konsekutiv wird Sulfatid gespeichert, vor allem im zentralen und peripheren Nervensystem, aber auch in Niere, Gallenblase und den Gallengangsepithelien der Leber. Die Speicherung führt zur einer weitreichenden zentralen und peripheren Demyelinisierung und dem Untergang glialer und neuronaler Zellen und somit zum Krankheitsbild der metachromatischen Leukodystrophie. Der pathogenetische Zusammenhang zwischen Sulfatid-Speicherung, Demyelinisierung und dem Zellverlust ist nach wie vor ungeklärt. Ein Tiermodell zur Untersuchung der metachromatischen Leukodystrophie steht mit einer ASA-Knockout-Maus zur Verfügung, ein etabliertes Zellmodell für die metachromatische Leukodystrophie gab es bislang nicht. In dieser Arbeit wurde ein in vitro-Modell zur Untersuchung der Pathogenese der metachromatischen Leukodystrophie entwickelt. Zunächst wurden lentivirale Vektoren mittels Calcium-Phosphat-Transfektion von HEK293T-Zellen hergestellt, die für die cDNAs der Cerebrosidsulfotransferase und der Ceramidgalaktosyltransferase kodierten. Diese beiden Enzyme sind für die Sulfatid-Biosynthese notwendig. Die Funktionstüchtigkeit der Vektoren sowie der übertragenen Enzyme wurde durch Transduktion von CHO-Zellen und Lipidanalyse mittels Dünnschichtchromatographie und Immundetektion bewiesen. ASA-defiziente Oligodendrozyten aus dem zentralen Nervensystem erwiesen sich durch aufwendige Präparation und niedrige Transduktionseffizienz als unbrauchbar für die biochemische Analyse. ASA-defiziente Schwann-Zellen aus dem peripheren Nervensystem wurden kombiniert mit den lentiviralen Vektoren für die cDNA der CST und die cDNA der CGT transduziert. Eine vermehrte Sulfatid-Speicherung im Vergleich zu untransduzierten Zellen konnte durch Immundetektion von Sulfatid nachgewiesen werden

Role of envelope glycoprotein complexes in cell-associated spread of human cytomegalovirus

The role of viral envelope glycoproteins, particularly the accessory proteins of trimeric and pentameric gH/gL-complexes, in cell-associated spread of human cytomegalovirus (HCMV) is unclear. We aimed to investigate their contribution in the context of HCMV variants that grow in a strictly cell-associated manner. In the genome of Merlin pAL1502, the glycoproteins gB, gH, gL, gM, and gN were deleted by introducing stop codons, and the mutants were analyzed for viral growth. Merlin and recent HCMV isolates were compared by quantitative immunoblotting for expression of accessory proteins of the trimeric and pentameric gH/gL-complexes, gO and pUL128. Isolates were treated with siRNAs against gO and pUL128 and analyzed regarding focal growth and release of infectious virus. All five tested glycoproteins were essential for growth of Merlin pAL1502. Compared with this model virus, higher gO levels were measured in recent isolates of HCMV, and its knockdown decreased viral growth. Knockdown of pUL128 abrogated the strict cell-association and led to release of infectivity, which allowed cell-free transfer to epithelial cells where the virus grew again strictly cell-associated. We conclude that both trimer and pentamer contribute to cell-associated spread of recent clinical HCMV isolates and downregulation of pentamer can release infectious virus into the supernatant

Chemical Clearing and Dehydration of GFP Expressing Mouse Brains

Generally, chemical tissue clearing is performed by a solution consisting of two parts benzyl benzoate and one part benzyl alcohol. However, prolonged exposure to this mixture markedly reduces the fluorescence of GFP expressing specimens, so that one has to compromise between clearing quality and fluorescence preservation. This can be a severe drawback when working with specimens exhibiting low GFP expression rates. Thus, we screened for a substitute and found that dibenzyl ether (phenylmethoxymethylbenzene, CAS 103-50-4) can be applied as a more GFP-friendly clearing medium. Clearing with dibenzyl ether provides improved tissue transparency and strikingly improved fluorescence intensity in GFP expressing mouse brains and other samples as mouse spinal cords, or embryos. Chemical clearing, staining, and embedding of biological samples mostly requires careful foregoing tissue dehydration. The commonly applied tissue dehydration medium is ethanol, which also can markedly impair GFP fluorescence. Screening for a substitute also for ethanol we found that tetrahydrofuran (CAS 109-99-9) is a more GFP-friendly dehydration medium than ethanol, providing better tissue transparency obtained by successive clearing. Combined, tetrahydrofuran and dibenzyl ether allow dehydration and chemical clearing of even delicate samples for UM, confocal microscopy, and other microscopy techniques

Downregulation of organic cation transporters OCT1 (SLC22A1) and OCT3 (SLC22A3) in human hepatocellular carcinoma and their prognostic significance

<p>Abstract</p> <p>Background</p> <p>Organic cation transporters (OCT) are responsible for the uptake and intracellular inactivation of a broad spectrum of endogenous substrates and detoxification of xenobiotics and chemotherapeutics. The transporters became pharmaceutically interesting, because OCTs are determinants of the cytotoxicity of platin derivates and the transport activity has been shown to correlate with the sensitivity of tumors towards tyrosine kinase inhibitors. No data exist about the relevance of OCTs in hepatocellular carcinoma (HCC).</p> <p>Methods</p> <p>OCT1 (<it>SLC22A1</it>) and OCT3 (<it>SLC22A3</it>) mRNA expression was measured in primary human HCC and corresponding non neoplastic tumor surrounding tissue (TST) by real time PCR (n = 53). Protein expression was determined by western blot analysis and immunofluorescence. Data were correlated with the clinicopathological parameters of HCCs.</p> <p>Results</p> <p>Real time PCR showed a downregulation of <it>SLC22A1 </it>and <it>SLC22A3 </it>in HCC compared to TST (p ≤ 0.001). A low <it>SLC22A1 </it>expression was associated with a worse patient survival (p < 0.05). Downregulation was significantly associated with advanced HCC stages, indicated by a higher number of T3 tumors (p = 0.025) with a larger tumor diameter (p = 0.035), a worse differentiation (p = 0.001) and higher AFP-levels (p = 0.019). In accordance, <it>SLC22A1 </it>was less frequently downregulated in tumors with lower stages who underwent transarterial chemoembolization (p < 0.001) and liver transplantation (p = 0.001). Tumors with a low <it>SLC22A1 </it>expression (< median) showed a higher <it>SLC22A3 </it>expression compared to HCC with high <it>SLC22A1 </it>expression (p < 0.001). However, there was no significant difference in tumor characteristics according to the level of the <it>SLC22A3 </it>expression.</p> <p>In the western blot analysis we found a different protein expression pattern in tumor samples with a more diffuse staining in the immunofluorescence suggesting that especially OCT1 is not functional in advanced HCC.</p> <p>Conclusion</p> <p>The downregulation of OCT1 is associated with tumor progression and a worse patient survival.</p

Torsional stability of interference screws derived from bovine bone - a biomechanical study

Introduction: It has been proposed that individual genetic variation contributes to the course of severe infections and sepsis. Recent studies of single nucleotide polymorphisms (SNPs) within the endotoxin receptor and its signaling system showed an association with the risk of disease development. This study aims to examine the response associated with genetic variations of TLR4, the receptor for bacterial LPS, and a central intracellular signal transducer (TIRAP/Mal) on cytokine release and for susceptibility and course of severe hospital acquired infections in distinct patient populations. Methods: Three intensive care units in tertiary care university hospitals in Greece and Germany participated. 375 and 415 postoperative patients and 159 patients with ventilator associated pneumonia (VAP) were included. TLR4 and TIRAP/Mal polymorphisms in 375 general surgical patients were associated with risk of infection, clinical course and outcome. In two prospective studies, 415 patients following cardiac surgery and 159 patients with newly diagnosed VAP predominantly caused by Gram-negative bacteria were studied for cytokine levels in-vivo and after ex-vivo monocyte stimulation and clinical course. Results: Patients simultaneously carrying polymorphisms in TIRAP/Mal and TLR4 and patients homozygous for the TIRAP/Mal SNP had a significantly higher risk of severe infections after surgery (odds ratio (OR) 5.5; confidence interval (CI): 1.34 - 22.64; P = 0.02 and OR: 7.3; CI: 1.89 - 28.50; P < 0.01 respectively). Additionally we found significantly lower circulating cytokine levels in double-mutant individuals with ventilator associated pneumonia and reduced cytokine production in an ex-vivo monocyte stimulation assay, but this difference was not apparent in TIRAP/Mal-homozygous patients. In cardiac surgery patients without infection, the cytokine release profiles were not changed when comparing different genotypes. Conclusions: Carriers of mutations in sequential components of the TLR signaling system may have an increased risk for severe infections. Patients with this genotype showed a decrease in cytokine release when infected which was not apparent in patients with sterile inflammation following cardiac surgery

Concise review : interferon-free treatment of hepatitis C virus-associated cirrhosis and liver graft infection

Chronic hepatitis C is a major reason for development of cirrhosis and hepatocellular carcinoma and a leading cause for liver transplantation. The development of direct-acting antiviral agents lead to (pegylated) interferon-alfa free antiviral therapy regimens with a remarkable increase in sustained virologic response (SVR) rates and opened therapeutic options for patients with advanced cirrhosis and liver graft recipients. This concise review gives an overview about most current prospective trials and cohort analyses for treatment of patients with liver cirrhosis and liver graft recipients. In patients with compensated cirrhosis Child-Pugh-Turcotte (CTP) class A, all approved agents are safe and SVR rates do not significantly differ from patients without cirrhosis in general. In patients with decompensated cirrhosis CTP class B or C, daclastasvir, ledipasvir, velpatasvir, and sofosbuvir are approved, and SVR rates higher than 90% can be achieved. Especially for patients with a model of end stage liver disease score higher than 15 and therefore eligible for liver transplantation, data is scarce. Reported SVR rates in patients with cirrhosis CTP class C are lower compared to patients with a less severe liver disease. In liver transplant recipients with a maximum of CTP class A, SVR rates are comparable to patients without LT. Patients with decompensated graft cirrhosis should be treated on an individual basis

Intractable ascites associated with mycophenolate in a simultaneous kidney-pancreas transplant patient: a case report

BACKGROUND: Mycophenolic acid (MPA), either given as an ester pro-drug or as an enteric-coated sodium salt, is the most commonly prescribed anti-proliferative immunosuppressive agent used following organ transplantation and widely applied in immune-mediated diseases. Clinicians are well aware of common adverse reactions related to MPA treatment, in particular diarrhea, leukopenia and infections. Here we report a case of severe, persistent ascites associated with MPA treatment. The otherwise unexplained and intractable ascites, requiring repeated paracenteses for more than 8 months, rapidly ceased with stopping the MPA treatment. To our knowledge this is the first case of severe ascites associated with MPA treatment reported in the scientific literature. CASE PRESENTATION: A 45-year old female with type 1 diabetes mellitus received a simultaneous kidney-pancreas transplant. The surgery was uneventful. However, post-operatively she developed severe transudative ascites requiring in total more than 40 paracenteses treatments draining in the average 2.8 l of ascites fluid. The ascites formation persisted despite exclusion of a surgical complication, fully functioning kidney and pancreas allografts, lack of any significant proteinuria, normalization of circulating albumin levels, intensive use of diuretics and deliberate attempts to increase the intervals between the paracentesis treatments. Various differential diagnoses, including infectious, hepatic, vascular and cardiac causes were ruled out. Nine months after surgery enteric-coated mycophenolate sodium was switched to azathioprine after which ascites completely resolved. When mycophenolate was recommenced abdominal fullness and weight gain reoccurred. The patient had to be switched to long-term azathioprine treatment. More than 1 year post-conversion the patient remains free of ascites. CONCLUSION: MPA is the most widely used antimetabolite immunosuppressive agent. We suggest to consider MPA treatment in the differential diagnosis of severe and unexplained ascites in transplant and non-transplant patients

Combined knockdown of RL13 and UL128 for release of cell-free infectivity from recent HCMV isolates

Due to strictly cell-associated growth, experiments requiring cell-free virus are not applicable to recent clinical HCMV isolates to date. On the other hand, adaptation to cell-free growth is associated with undesirable changes in the viral gene regions RL13 and UL128. We had previously found that siRNA-mediated reduction of UL128 expression allowed transient release of cell-free virus by clinical isolates, and now hypothesized that virus yield could be further increased by additional knockdown of RL13. Despite the extensive polymorphism of RL13, effective RL13-specific siRNAs could be designed for three recent isolates and the Merlin strain. Knockdown efficiency was demonstrated at the protein level with a Merlin variant expressing V5-tagged pRL13. Knockdown of RL13 alone did not result in measurable release of cell-free virus, but combined knockdown of RL13 and UL128 increased infectivity in cell-free supernatants by a factor of 10–2000 compared to knockdown of UL128 alone. These supernatants could be used in dose-response assays to compare the effect of a neutralizing antibody on the various HCMV isolates. In summary, combined knockdown of RL13 and UL128 by specific siRNAs allows reliable release of cell-free infectivity from otherwise strictly cell-associated HCMV isolates without the need to modify the viral genome