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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Anti-Vascular endothelial growth factor therapy impairs endothelial function of retinal microcirculation in colon cancer patients – an observational study

Reimann, Manja, Folprecht, Gunnar, Haase, Rocco, Trautmann, Karolin, Ehninger, Gerhard, Reichmann, Heinz, Ziemssen, Focke, Ziemssen, Tjalf 22 January 2014 (has links)
Background: To assess acute effects of bevacizumab (anti-VEGF therapy) on cerebral microvessels and systemic cardiovascular regulation. Design and subjects: 20 consecutive patients with colorectal cancer (median age: 60.4 years, range 45.5-73.9 years) received bevacizumab intravenously (5 mg/kg) uncoupled of chemotherapy. Prior to and within the first 24 hours after bevacizumab infusion, patients were investigated for retinal endothelial function. A series of a triple 24-hour ambulatory blood pressure measurement was conducted. Retinal endothelial function was determined as flicker light-induced vasodilation. The integrity of baroreflex arc and autonomic cardiovascular control was examined by stimulatory manoeuvres. Results: Bevacizumab therapy significantly reduced the vasodilatory capacity of retinal arterioles in response to flicker light. A slight decrease in diastolic pressure and heart rate was observed after bevacizumab infusion but this was unrelated to changes in retinal function. The pressure response upon nitroglycerin was largely preserved after bevacizumab infusion. The proportion of patients with abnormal nocturnal blood pressure regulation increased under anti-angiogenic therapy. Autonomic blood pressure control was not affected by bevacizumab treatment. Conclusions: Bevacizumab acutely impairs microvascular function independent of blood pressure changes. Imaging of the retinal microcirculation seems a valuable tool for monitoring pharmacodynamic effects of bevacizumab.
82

Atypical Central Neurocytoma with Recurrent Spinal Dissemination over a Period of 20 Years: A Case Report and Review of the Literature

Juratli, Tareq A., Geiger, Kathrin, Leimert, Mario, Schackert, Gabriele, Kirsch, Matthias 22 January 2014 (has links)
We present an unusual case of a late recurrent central neurocytoma that was rediagnosed as an ependymoma and neurocytoma in accordance with changes in histological classifications. Case Description. A 56-year-old male teacher presented with incomplete transverse syndrome due to several intradural extramedullary tumors at the level of lumbar vertebrae 1–3. The histological diagnosis at the time was atypical ependymoma. One year later, two additional tumors were removed at the L5-S1 vertebral level. For 12 years, the patient remained tumor free on followup. Fourteen years after the initial diagnosis, the patient presented with thoracic paresthesias due to two new extramedullary tumors in the C7-T1 and the T8-T9 vertebral levels. After complete removal of the tumors, a radiological survey revealed an intracranial lesion in the third ventricle. Five months later, an additional lesion recurrence was removed surgically. The most recent histological diagnosis revealed an atypical central neurocytoma. In retrospect, the previous tumors were reclassified as neurocytoma according to the additional immunohistochemistry evidence. Discussion. There is no standard adjuvant treatment regimen for atypical neurocytoma; therefore, the patient is currently under close followup. Modern histopathological diagnosis is essential in these cases. Potential routes for dissemination of the tumor should be considered upon first recurrence.
83

Do current screening recommendations allow for early detection of lithium-induced hyperparathyroidism in patients with bipolar disorder?

Berger, Michael, Riedel, Michael, Tomova, Nora, Obermeier, Michael, Seemüller, Florian, Dittmann, Sandra, Möller, Hans-Jürgen, Severus, Emanuel 22 January 2014 (has links)
Background: Current screening recommendations for early detection of lithium-associated hyperparathyroidism propose an exclusive measurement of serum albumin-adjusted calcium (Aac) concentration as a single first step. However, longitudinal data in patients with recurrent affective disorders suggest that increases in serum intact parathyroid hormone (iPTH) levels in lithium-treated patients may not necessarily be accompanied by a parallel increase in the concentration of Aac. If true, patients with an isolated increase in iPTH concentration above the reference range might be missed following current screening recommendations. Therefore, this study set out to examine key parameters of calcium metabolism, including iPTH and 25-hydroxycholecalciferol concentrations in patients with bipolar disorder that was or was not managed with lithium. Methods: Sixty patients with bipolar disorder according to DSM-IV were enrolled, 30 of whom had received long-term lithium treatment (lithium group), whereas the other 30 patients were on psychopharmacological treatment not including lithium (non-lithium group) at the time of the study. Owing to exclusion criteria (e.g., lithium < 6 months, laboratory results indicative of secondary hyperparathyroidism), 23 bipolar patients composed the final lithium group, whereas 28 patients remained in the non-lithium group for statistical analyses. Results: Patients in the lithium group showed a significantly higher concentration of iPTH compared to the non-lithium group (p < 0.05). Similarly, Aac concentrations were significantly increased in the lithium group compared to the non-lithium group (p < 0.05). However, in a multivariate linear regression model, group affiliation only predicted iPTH concentration (p < 0.05). In line with this, none of the four patients in the lithium group with an iPTH concentration above the reference range had an Aac concentration above the reference range. Discussion: This study suggests that the biochemical characteristics between primary hyperparathyroidism and lithium-induced hyperparathyroidism differ substantially with regard to regulation of calcium homeostasis. As such, current screening practice does not reliably detect iPTH concentrations above the reference range. Therefore, further research is needed to elucidate the consequences of an isolated iPTH concentration above the reference range in order to develop the most appropriate screening tools for hyperparathyroidism in lithium-treated patients with bipolar disorder.
84

Development of Eimeria nieschulzi (Coccidia, Apicomplexa) Gamonts and Oocysts in Primary Fetal Rat Cells

Chen, Hong, Wiedmer, Stefanie, Hanig, Sacha, Entzeroth, Rolf, Kurth, Michael 22 January 2014 (has links)
The in vitro production of gametocytes and oocysts of the apicomplexan parasite genus Eimeria is still a challenge in coccidiosis research. Until today, an in vitro development of gametocytes or oocysts had only been shown in some Eimeria species. For several mammalian Eimeria species, partial developments could be achieved in different cell types, but a development up to gametocytes or oocysts is still lacking. This study compares several permanent cell lines with primary fetal cells of the black rat (Rattus norvegicus) concerning the qualitative in vitro development of the rat parasite Eimeria nieschulzi. With the help of transgenic parasites, the developmental progress was documented. The selected Eimeria nieschulzi strain constitutively expresses the yellow fluorescent protein and a macrogamont specific upregulated red tandem dimer tomato. In the majority of all investigated host cells the development stopped at the second merozoite stage. In a mixed culture of cells derived from inner fetal organs the development of schizont generations I-IV, macrogamonts, and oocysts were observed in crypt-like organoid structures. Microgamonts and microgametes could not be observed and oocysts did not sporulate under air supply. By immunohistology, we could confirm that wild-type E. nieschulzi stages can be found in the crypts of the small intestine. The results of this study may be helpful for characterization of native host cells and for development of an in vitro cultivation system for Eimeria species.
85

Candidatus Megaira polyxenophila' gen. nov., sp. nov.: Considerations on Evolutionary History, Host Range and Shift of Early Divergent Rickettsiae

Schrallhammer, Martina, Ferrantini, Filippo, Vannini, Claudia, Galati, Stefano, Schweikert, Michael, Görtz, Hans-Dieter, Verni, Franco, Petroni, Giulio 28 November 2013 (has links)
“Neglected Rickettsiaceae” (i.e. those harboured by non-hematophagous eukaryotic hosts) display greater phylogenetic variability and more widespread dispersal than pathogenic ones; yet, the knowledge about their actual host range and host shift mechanism is scarce. The present work reports the characterization following the full-cycle rRNA approach (SSU rRNA sequence, specific in situ hybridization, and ultrastructure) of a novel rickettsial bacterium, herewith proposed as 'Candidatus Megaira polyxenophila' gen. nov., sp. nov. We found it in association with four different free-living ciliates (Diophrys oligothrix, Euplotes octocarinatus, Paramecium caudatum, and Spirostomum sp., all belonging to Alveolata, Ciliophora); furthermore it was recently observed as intracellular occurring in Carteria cerasiformis and Pleodorina japonica (Chlorophyceae, Chlorophyta). Phylogenetic analyses demonstrated the belonging of the candidate new genus to the family Rickettsiaceae (Alphaproteobacteria, Rickettsiales) as a sister group of the genus Rickettsia. In situ observations revealed the ability of the candidate new species to colonize either nuclear or cytoplasmic compartments, depending on the host organism. The presence of the same bacterial species within different, evolutionary distant, hosts indicates that 'Candidatus Megaira polyxenophila' recently underwent several distinct host shifts, thus suggesting the existence of horizontal transmission pathways. We consider these findings as indicative of an unexpected spread of rickettsial infections in aquatic communities, possibly by means of trophic interactions, and hence propose a new interpretation of the origin and phylogenetic diversification of rickettsial bacteria.
86

Thunderbolt in biogeochemistry: galvanic effects of lightning as another source for metal remobilization

Schaller, Jörg, Weiske, Arndt, Berger, Frank 06 February 2014 (has links)
Iron and manganese are relevant constituents of the earth's crust and both show increasing mobility when reduced by free electrons. This reduction is known to be controlled by microbial dissimilation processes. Alternative sources of free electrons in nature are cloud-to-ground lightning events with thermal and galvanic effects. Where thermal effects of lightning events are well described, less is known about the impact of galvanic lightning effects on metal mobilization. Here we show that a significant mobilization of manganese occurs due to galvanic effects of both positive and negative lightning, where iron seems to be unaffected with manganese being abundant in oxic forms in soils/sediments. A mean of 0.025 mmol manganese (negative lightning) or 0.08 mmol manganese (positive lightning) mobilization may occur. We suggest that lightning possibly influences biogeochemical cycles of redox sensitive elements in continental parts of the tropics/subtropics on a regional/local scale.
87

Development of β-Lactamase as a Tool for Monitoring Conditional Gene Expression by a Tetracycline-Riboswitch in Methanosarcina acetivorans

Demolli, Shemsi, Geist, Miriam M., Weigand, Julia E., Matschiavelli, Nicole, Süß, Beatrix, Rother, Michael 06 February 2014 (has links)
The use of reporter gene fusions to assess cellular processes such as protein targeting and regulation of transcription or translation is established technology in archaeal, bacterial, and eukaryal genetics. Fluorescent proteins or enzymes resulting in chromogenic substrate turnover, like β-galactosidase, have been particularly useful for microscopic and screening purposes. However, application of such methodology is of limited use for strictly anaerobic organisms due to the requirement of molecular oxygen for chromophore formation or color development. We have developed β-lactamase from Escherichia coli (encoded by bla) in conjunction with the chromogenic substrate nitrocefin into a reporter system usable under anaerobic conditions for the methanogenic archaeon Methanosarcina acetivorans. By using a signal peptide of a putative flagellin from M. acetivorans and different catabolic promoters, we could demonstrate growth substrate-dependent secretion of β-lactamase, facilitating its use in colony screening on agar plates. Furthermore, a series of fusions comprised of a constitutive promoter and sequences encoding variants of the synthetic tetracycline-responsive riboswitch (tc-RS) was created to characterize its influence on translation initiation in M. acetivorans. One tc-RS variant resulted in more than 11-fold tetracycline-dependent regulation of bla expression, which is in the range of regulation by naturally occurring riboswitches. Thus, tc-RS fusions represent the first solely cis-active, that is, factor-independent system for controlled gene expression in Archaea.
88

Positioning of term infants during delivery room routine handling – analysis of videos

Konstantelos, Dimitrios, Gurth, Heidrun, Bergert, Renate, Ifflaender, Sascha, Rüdiger, Mario 07 July 2014 (has links)
Background: Delivery room management (DR) of the newly born infant should be performed according to international guidelines, but no recommendations are available for an infant’s position immediately after birth. The present study was performed to answer the following questions: 1. How often is DR-management performed in term infants in side position? 2. Is routine DR-management possible in side position? 3. Is there any benefit of side position with respect to agitation or vital parameters? Methods: Cross-sectional study of video-recorded DR-management in term newborns delivered by C-section in 2012. Videos were analysed for infant’s position, administered interventions, vital parameters and agitation. Results: 187 videos were analysed. The Main Position (defined as position spent more than 70% of the time) was “supine” in 91, “side” in 63 and “not determinable” in 33 infants. “Supine” infants received significantly (p < 0.001) more often stimulation (12.5% of the total time) than “side” infants (3.9% of time). There were no differences between both groups with regard to suctioning; CPAP was exclusively (98%) administered in supine position. Newborns on side were less agitated than those on supine. There was a trend towards a better oxygenation in “side” positioned infants (p = 0.055) and significantly (p = 0.04) higher saturation values in “left-sided” infants than “right-sided” infants at 8th minute. “Side” positioned infants reached oxygen saturation values >90% earlier than “supine” positioned infants (p = 0.16). Conclusions: DR-management is feasible in the side position in term infants. Side position seems to be associated with reduced agitation and improved oxygenation. However, it remains unclear whether this represents a causal relationship or an association. The study supports the need for a randomized controlled trial.
89

Stage-dependent prognostic impact of molecular signatures in clear cell renal cell carcinoma

Weber, Thomas, Meinhardt, Matthias, Zastrow, Stefan, Wienke, Andreas, Erdmann, Kati, Hofmann, Jörg, Füssel, Susanne, Wirth, Manfred P. 09 July 2014 (has links)
Purpose: To enhance prognostic information of protein biomarkers for clear cell renal cell carcinomas (ccRCCs), we analyzed them within prognostic groups of ccRCC harboring different tumor characteristics of this clinically and molecularly heterogeneous tumor entity. Methods: Tissue microarrays from 145 patients with primary ccRCC were immunohistochemically analyzed for VHL (von Hippel-Lindau tumor suppressor), Ki67 (marker of proliferation 1), p53 (tumor protein p53), p21 (cyclin-dependent kinase inhibitor 1A), survivin (baculoviral IAP repeat containing 5), and UEA-1 (ulex europaeus agglutinin I) to assess microvessel-density. Results: When analyzing all patients, nuclear staining of Ki67 (hazard ratio [HR] 1.08, 95% confidence interval [CI] 1.04–1.12) and nuclear survivin (nS; HR 1.04, 95% CI 1.01–1.08) were significantly associated with disease-specific survival (DSS). In the cohort of patients with advanced localized or metastasized ccRCC, high staining of Ki67, p53 and nS predicted shorter DSS (Ki67: HR 1.07, 95% CI 1.02–1.11; p53: HR 1.05, 95% CI 1.01–1.09; nS: HR 1.08, 95% CI 1.02–1.14). In organ-confined ccRCC, patients with high p21-staining had a longer DSS (HR 0.96, 95% CI 0.92–0.99). In a multivariate model with stepwise backward elimination, tumor size and p21-staining showed a significant association with DSS in patients with 'organ-confined' ccRCCs. The p21-staining increased the concordance index of tumor size from 0.75 to 0.78. In patients with 'organ-confined' ccRCC, no disease-related deaths occurred in the group with p21-expression below the threshold of 32.5% p21-positive cells (log rank test: P=0.002). Conclusion: The prognostic information of the studied protein biomarkers depended on anatomic tumor stages, which displayed different acquired biological tumor characteristics. Analysis of prognostic factors within different clinical ccRCC groups could help to enhance their prognostic power. The p21-staining was an independent prognostic factor and increased prognostic accuracy in a predictive model in 'organ-confined' ccRCC.
90

Comprehensive histological evaluation of bone implants

Rentsch, Claudia, Schneiders, Wolfgang, Manthey, Suzanne, Rentsch, Barbe, Rammelt, Stefan 14 July 2014 (has links)
To investigate and assess bone regeneration in sheep in combination with new implant materials classical histological staining methods as well as immunohistochemistry may provide additional information to standard radiographs or computer tomography. Available published data of bone defect regenerations in sheep often present none or sparely labeled histological images. Repeatedly, the exact location of the sample remains unclear, detail enlargements are missing and the labeling of different tissues or cells is absent. The aim of this article is to present an overview of sample preparation, staining methods and their benefits as well as a detailed histological description of bone regeneration in the sheep tibia. General histological staining methods like hematoxylin and eosin, Masson-Goldner trichrome, Movat’s pentachrome and alcian blue were used to define new bone formation within a sheep tibia critical size defect containing a polycaprolactone-co-lactide (PCL) scaffold implanted for 3 months (n = 4). Special attention was drawn to describe the bone healing patterns down to cell level. Additionally one histological quantification method and immunohistochemical staining methods are described.

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