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Search Results: 1 - 10 of 938 matches for " Kerstin Birke "
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Topical Application of PPADS Inhibits Complement Activation and Choroidal Neovascularization in a Model of Age-Related Macular Degeneration
Kerstin Birke, Erion Lipo, Marco T. Birke, Rajendra Kumar-Singh
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076766
Abstract: Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly. AMD patients have elevated levels of membrane attack complex (MAC) in their choroidal blood vessels and retinal pigment epithelium (RPE). MAC forms pores in cell membranes. Low levels of MAC result in an elevation of cytokine release such as vascular endothelial growth factor (VEGF) that promotes the formation of choroidal neovascularization (CNV). High levels of MAC result in cell lysis and RPE degeneration is a hallmark of advanced AMD. The current standard of care for CNV associated with wet AMD is intravitreal injection of anti-VEGF molecules every 4 to 12 weeks. Such injections have significant side effects. Recently, it has been found that membrane pore-forming proteins such as α-haemolysin can mediate their toxic effects through auto- and paracrine signaling and that complement-induced lysis is amplified through ATP release followed by P2X receptor activation. We hypothesized that attenuation of P2X receptor activation may lead to a reduction in MAC deposition and consequent formation of CNV. Hence, in this study we investigated topical application of the purinergic P2X antagonist Pyridoxalphosphate-6-azophenyl-2',4'-dis?ulphonicacid (PPADS) as a potential treatment for AMD. We found that 4.17 μM PPADS inhibited formation of HUVEC master junctions and master segments by 74.7%. In a human complement mediated cell lysis assay, 104 μM PPADS enabled almost complete protection of Hepa1c1c7 cells from 1% normal human serum mediated cell lysis. Daily topical application of 4.17 mM PPADS for 3 days attenuated the progression of laser induced CNV in mice by 41.8% and attenuated the deposition of MAC at the site of the laser injury by 19.7%. Our data have implications for the future treatment of AMD and potentially other ocular disorders involving CNV such as angioid streaks, choroidal rupture and high myopia.
Preventive Effects of Omega-3 and Omega-6 Fatty Acids on Peroxide Mediated Oxidative Stress Responses in Primary Human Trabecular Meshwork Cells
Theofilos Tourtas, Marco T. Birke, Friedrich E. Kruse, Ulrich-Christoph Welge-Lüssen, Kerstin Birke
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031340
Abstract: Pathologic processes in glaucoma include increased apoptosis, accumulation of extracellular material in the trabecular meshwork and optic nerve, condensations of the cytoskeleton and precocious cellular senescence. Oxidative stress was shown to generate these alterations in primary ocular cells. Fatty acids omega-3 and -6 are alleged to constitute a prophylaxis against these deleterious effects. Here, we tested actual preventive effects omega-3 and -6 against peroxide induced stress responses in primary human trabecular meshwork cells. Changes of mitochondrial activity, proliferation, heat shock proteins, extracellular matrix components, and inflammatory markers were evaluated. Alterations of the cytoskeleton were evaluated by phalloidin labeling. Here we report a repressive effect of omega-6 on metabolic activity and proliferation, which was not detected for omega-3. Both agents were able to prevent the anti-proliferative effect of H2O2, but only omega-3 prevented metabolic repression. Expression of heat shock protein 27 was unaltered by both fatty acids, whereas heat shock protein 90 was significantly induced by both. Omega-6 increased fibronectin and connective tissue growth factor synthesis, as well as the amount of secreted fibronectin. Omega-3, instead, induced plasminogen activator inhibitor 1 synthesis. H2O2 further increased fibronectin production in omega-6 supplemented cells, which was not the case in omega-3 treated cells. H2O2 stimulation of plasminogen activator inhibitor 1 and connective tissue growth factor was repressed by both fatty acids. Both fatty acids appeared to abolish H2O2 mediated stimulation of nuclear factor κB and IL-6, but not IL-1α and IL-8. H2O2 induced formation of cross-linked actin networks and stress fibers, which was reduced by preemptive application of omega-3. Omega-6, in contrast, had no protective effect on that, and even seemed to promote condensation. Based on the observed side effects of omega-6, omega-3 appears to be the more beneficial fatty acid in respect of prophylactic intake for prevention of a glaucomatous disease.
Biological Effects of Cigarette Smoke in Cultured Human Retinal Pigment Epithelial Cells
Alice L. Yu, Kerstin Birke, Johannes Burger, Ulrich Welge-Lussen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048501
Abstract: The goal of the present study was to determine whether treatment with cigarette smoke extract (CSE) induces cell loss, cellular senescence, and extracellular matrix (ECM) synthesis in primary human retinal pigment epithelial (RPE) cells. Primary cultured human RPE cells were exposed to 2, 4, 8, and 12% of CSE concentration for 24 hours. Cell loss was detected by cell viability assay. Lipid peroxidation was assessed by loss of cis-parinaric acid (PNA) fluorescence. Senescence-associated ?-galactosidase (SA-?-Gal) activity was detected by histochemical staining. Expression of apolipoprotein J (Apo J), connective tissue growth factor (CTGF), fibronectin, and laminin were examined by real-time PCR, western blot, or ELISA experiments. The results showed that exposure of cells to 12% of CSE concentration induced cell death, while treatment of cells with 2, 4, and 8% CSE increased lipid peroxidation. Exposure to 8% of CSE markedly increased the number of SA-?-Gal positive cells to up to 82%, and the mRNA expression of Apo J, CTGF, and fibronectin by approximately 3–4 fold. Treatment with 8% of CSE also increased the protein expression of Apo J and CTGF and the secretion of fibronectin and laminin. Thus, treatment with CSE can induce cell loss, senescent changes, and ECM synthesis in primary human RPE cells. It may be speculated that cigarette smoke could be involved in cellular events in RPE cells as seen in age-related macular degeneration.
Hepatitis B and C Viruses and Hepatocellular Carcinoma
Birke Bartosch
Viruses , 2010, DOI: 10.3390/v2081504
Abstract: Chronic liver disease is responsible for over 1.4 million deaths annually ?[1] and is characterized by permanent inflammatory processes that predispose to liver cancer and in particular hepatocellular carcinoma (HCC). In healthy liver, inflammatory processes stimulate growth and repair and restore normal liver architecture. However, if liver inflammation becomes chronic, the balance of damage versus regeneration in the liver is disrupted and can lead to the formation of excessive scar tissue, termed fibrosis. In the long-term, an exacerbation of fibrosis will lead to cirrhosis, which is characterized by abnormal liver architecture and function and is associated with a significant reduction in overall health and wellbeing. At cirrhotic stages, liver damage is often irreversible or difficult to treat. Cirrhosis leads frequently to death from liver failure or to HCC (Figure 1). Indeed, HCC is the first cause of death in cirrhotic patients?[2], and is a tumor with poor prognosis, ranking third in terms of death by cancer. Furthermore, it is the fifth most prevalent cancer worldwide, with 800,000 new cases per year in the world?[2,3]. [...]
Hallo, wer spricht?“ Kommentar zu Margit Mayers Urbane soziale Bewegungen in der neoliberalisierenden Stadt“
Peter Birke
s u b u r b a n : zeitschrift für kritische stadtforschung , 2013,
Abstract: [Dieser Artikel ist Teil einer Debatte] Die von Margit Mayer vorgestellten Vorschl ge zur theoretischen Verortung der aktuellen stadtpolitischen Bewegungen sind aus meiner Sicht sehr wichtig. Kein Zweifel kann daran bestehen, dass eine flie ende, historisierende Sichtweise notwendig ist, die die fragmentierenden Wirkungen der Neoliberalisierung“ betont. Dies ist ein berechtigter Hinweis auf die Kurzschlüsse, die gerade auch in der marxistisch inspirierten politischen Linken verbreitet waren und sind, in denen Neoliberalismus“ als eine Figur, als eine Art gro es Monster gezeichnet worden ist, das sich immer“ und überall“, also überhistorisch und lückenlos durchzusetzen scheint. Von sehr gro er und sogar zunehmender Bedeutung erscheint mir auf dieser Grundlage auch der Versuch, eine Einteilung vorzunehmen, die die konomie der aktuellen Krise diesem historischen Prozess zuordnet und (was im Rahmen des vorliegenden Textes natürlich nur angedeutet werden kann) die Bezugnahme zwischen globalen, nationalstaatlichen und lokal-urbanen Austerit tspolitiken thematisiert. Ebenso wichtig wie schlüssig sind auch die Hinweise auf gegenw rtige Polarisierungstendenzen, die in diesem Kontext zu bemerken sind, so auch die Polarisierung von wachsenden“ und schrumpfenden“ Territorien und – was ja gerade die Pointe dieses Textes ist – der verschiedenen Pole der Sozialbewegungen selbst.
Active and Healthy Ageing at Work—A Qualitative Study with Employees 55 - 63 Years and Their Managers  [PDF]
Kerstin Nilsson
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.57002
Abstract: The proportion of elderly individuals in the population is increasing in most industrial countries. This demographic change increases the need of more people who work until an older age to maintain the welfare in the states. However, it is not clear if older employees are interested to in generally extend the working life to an older age. It is also not stated if managers in organizations are interested of extending their older employees working life. The overall aim of this study was to examine older employees own experience of their work situation and ageing at work. The aim was also to investigate their managers’ attitude to them as older employees. The investigation was conducted by focusing group interviews with employees aged 55 - 63 years, and with their mangers aged 40 - 63 years. The findings stated that the older employees’ consideration for an extend working life seemed to be based on their health and health problems in relation to their work situation; their personal economy; their managers attitude to them as elderly and the possibility to social inclusion at work; and their possibilities for self-crediting activities at work despite their age. The managers seem to have a positive attitude to some of the older employees’ experience knowledge, if that was in the same direction as their own interest. Otherwise the mangers saw the older employees as problem and obsoleted. The managers were also negative to older employees who got health problems which effect the work production negatively. The older workers in this study described managers’ importance to if they want to work in an extended working life. However, the managers seem not to understand their own importance in this and were not interested to keep all elderly in an extended working life.
The Influence of Work Environmental and Motivation Factors on Seniors’ Attitudes to an Extended Working Life or to Retire. A Cross Sectional Study with Employees 55 - 74 Years of Age  [PDF]
Kerstin Nilsson
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.57003
Abstract: Aim: The aim of this study was to investigate difference between whether individuals think they can work, and want to work until 65 years or not. Methods: A cross/sectional study including survey of 1949 employees aged 55 - 74 years. Results: Working environments were the most significant differences between the groups associated to if the respondents think they can work beyond 65 years or not. Motivation factors were the most significant differences between the groups associated with if the respondents want to work beyond 65 years or not. Conclusions: A satisfying work environment is important to whether people think they can work or not. Nevertheless, whether people want to work is depending on whether the employees are satisfied with the factors that promote their motivation for work. If society wants more people to work until an upper age, it is important to improve both work environmental factors and motivation factors in their work situation.
Detection of Postoperative Intestinal Ischemia in Small Bowel Transplants
Hanne Birke-Sorensen
Journal of Transplantation , 2012, DOI: 10.1155/2012/970630
Abstract: Small bowel transplantation is acknowledged as auto- and allotransplantation. In both instances, there is up to a 4%–10% risk of postoperative ischemia, and as the small bowel is extremely susceptible to ischemia, the timely diagnosis of ischemia is important. The location of the transplant, whether it is buried in the abdominal cavity or in the neck region, increases the challenge, as monitoring becomes more difficult and the consequences of neglect more dangerous. All methods for the early detection of postoperative ischemia in small bowel transplants are described together with the requirements of the ideal monitoring method. A small bowel transplant can be inspected directly or indirectly; the blood flow can be monitored by Doppler or by photoplethysmography, and the consequences of the blood flow can be monitored. The ideal monitoring method should be reliable, fast, minimally invasive, safe, objective, easy, cheap, and comfortable. No monitoring methods today fulfill the criteria of the ideal monitoring method, and evidence-based guidelines regarding postoperative monitoring cannot be made. The choice of whether to implement monitoring of ischemia—and if so, which method to choose—has to be made by the individual surgeon or center.
Recent Advances in Hepatitis C Virus Cell Entry
Birke Bartosch,Jean Dubuisson
Viruses , 2010, DOI: 10.3390/v2030692
Abstract: More than 170 million patients worldwide are chronically infected with hepatitis C virus (HCV). Prevalence rates range from 0.5% in Northern European countries to 28% in some areas of Egypt. HCV is hepatotropic, and in many countries chronic hepatitis C is a leading cause of liver disease including fibrosis, cirrhosis and hepatocellular carcinoma. HCV persists in 50–85% of infected patients, and once chronic infection is established, spontaneous clearance is rare. HCV is a member of the Flaviviridae family, in which it forms its own genus. Many lines of evidence suggest that the HCV life cycle displays many differences to that of other Flaviviridae family members. Some of these differences may be due to the close interaction of HCV with its host’s lipid and particular triglyceride metabolism in the liver, which may explain why the virus can be found in association with lipoproteins in serum of infected patients. This review focuses on the molecular events underlying the HCV cell entry process and the respective roles of cellular co-factors that have been implied in these events. These include, among others, the lipoprotein receptors low density lipoprotein receptor and scavenger receptor BI, the tight junction factors occludin and claudin-1 as well as the tetraspanin CD81. We discuss the roles of these cellular factors in HCV cell entry and how association of HCV with lipoproteins may modulate the cell entry process.
Detection of Postoperative Intestinal Ischemia in Small Bowel Transplants
Hanne Birke-Sorensen
Journal of Transplantation , 2012, DOI: 10.1155/2012/970630
Abstract: Small bowel transplantation is acknowledged as auto- and allotransplantation. In both instances, there is up to a 4%–10% risk of postoperative ischemia, and as the small bowel is extremely susceptible to ischemia, the timely diagnosis of ischemia is important. The location of the transplant, whether it is buried in the abdominal cavity or in the neck region, increases the challenge, as monitoring becomes more difficult and the consequences of neglect more dangerous. All methods for the early detection of postoperative ischemia in small bowel transplants are described together with the requirements of the ideal monitoring method. A small bowel transplant can be inspected directly or indirectly; the blood flow can be monitored by Doppler or by photoplethysmography, and the consequences of the blood flow can be monitored. The ideal monitoring method should be reliable, fast, minimally invasive, safe, objective, easy, cheap, and comfortable. No monitoring methods today fulfill the criteria of the ideal monitoring method, and evidence-based guidelines regarding postoperative monitoring cannot be made. The choice of whether to implement monitoring of ischemia—and if so, which method to choose—has to be made by the individual surgeon or center. 1. Introduction Small bowel transplantation (SBT) is an acknowledged therapy as autotransplant for the reconstruction of the upper gastrointestinal tract (mouth, oropharynx, and esophagus) and as an allotransplant for the surgical treatment of short bowel syndrome (pure SBT and in combination with other organs) [1, 2]. In both instances, there is up to a 4%–10% risk of postoperative intestinal ischemia in the transplant (POII) [3, 4]. The risk of POII is increased if there is an increased risk of arterial or venous thrombosis, if there is an increased risk of hypoperfusion [5], and if there is an increased risk of compression of the SBT and the vessels after closure of the wound [6]. In auto- as well as allotransplants, the survival of the SBT is of outmost importance, and as the small bowel is extremely susceptible to ischemia, the timely diagnosis of POII is essential. Detection of POII in SBT is difficult as the transplant is hidden. The allotransplant is placed intraabdominally and the autotransplant is hidden in the neck region. The abovementioned sensitivity of the SBT in combination with the position of the transplant amplifies the importance of the detection of POII, as neglected POII represents a life-threatening situation. One reason for the importance of detecting POII is that it can aim at an urgent and
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