Nach oben pdf Transmission of Porcine Circovirus 3 (PCV3) by Xenotransplantation of Pig Hearts into Baboons

Transmission of Porcine Circovirus 3 (PCV3) by Xenotransplantation of Pig Hearts into Baboons

Transmission of Porcine Circovirus 3 (PCV3) by Xenotransplantation of Pig Hearts into Baboons

This is the first report showing trans-species transmission of PCV3 to baboons by the transplantation of a heart from a PCV3-positive donor pig. The correlation between the survival time of the transplant in the recipient and the virus load in the organs of the transplanted baboon suggests that the virus was replicating in the animals. PCV3 was found in the removed pig heart after the end of the study as well as in all organs of the baboons. The highest virus load was found in the liver or spleen of the baboons (Figure 1). It remains still unclear whether PCV3 infects baboon cells or whether the replication is only ongoing in the pig heart and the virus is distributed in the baboon with virus-producing pig cells or as free virus in the blood stream. Incubating mitogen-stimulated pig PBMCs from PCV3-positive pigs with human 293 cells as target cells did not result in infection of the 293 cells. Mitogen stimulation was used, because in several publications it has been shown that the related PCV2 was stimulated in mitogen-treated PBMCs [4,25–27]. The T-cell mitogen concanavalin A (ConA) enhanced PCV2 replication not only in vitro, but also in lymphoid tissues in vivo [25]. Treatment with IL-2, ConA, and D-glycosamine increased the PCV2 yield more effectively than other treatments [26]. Furthermore, ConA together with methyl-beta-cyclodextrin (MβCD) and D-glucosamine also increased the PCV2 replication in pig kidney cells (PK15) [26]. Here we used another T-cell mitogen, PHA, which also simulates an immune response of the T lymphocytes, for the stimulation of PBMCs. An increased replication after mitogen-stimulation of pig PBMCs was shown not only for PCV2 [4,25–27], but also for PCMV [28] and PERV [29]. The fact that human 293 cells were not infected with PCV3 in this first experiment does not mean that human cell cannot be infected with PCV3. There may be several reasons for the
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Porcine Circoviruses and Xenotransplantation

Porcine Circoviruses and Xenotransplantation

Allotransplantation can be associated with transmission of microorganisms which induce severe diseases in the recipient [1,2]. Among the transmitted microorganisms are bacteria [3] and viruses such as the human immunodeficiency virus-1 [4], rabies virus [5–7], and human cytomegalovirus (HCMV) [8]. Infection with HCMV is a common complication after transplantation of different organs and contributes significantly to morbidity and mortality, both by direct and indirect mechanisms [9]. Therefore, HCMV status has to be determined and transplantations from HCMV-positive individuals to HCMV-negative individuals are generally avoided (for review see [8,9]). If necessary, an antiviral treatment is available and new antiviral drugs are under development [10]. Xenotransplantation using pig cells, tissues, and organs may also be associated with transmission of microorganisms, including bacteria, viruses, and others from the donor pig [11]. Transmission of porcine cytomegalovirus (PCMV) with the transplant and its increased replication, also called reactivation, on the background of the absence of the pig immune system and of the applied immunosuppression in the non-human primate recipient, was observed after pig kidney transplantations into baboons [12] or cynomolgus monkeys [13]. Transmission of PCMV was also observed after pig heart transplantations into baboons [14]. Although the virus titre in the recipients increases, it is unclear whether PCMV is able to infect cells of the recipient or is replicating only in the cells of the transplant.
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Distribution of Porcine Cytomegalovirus in Infected Donor Pigs and in Baboon Recipients of Pig Heart Transplantation

Distribution of Porcine Cytomegalovirus in Infected Donor Pigs and in Baboon Recipients of Pig Heart Transplantation

a large number of individuals die on the waiting list for the required organ [ 2 ]. Pigs are for several reasons the most suitable donor species. These reasons include the size of the organs, the functional compatibility (for example, pig insulin has been used successfully for the treatment of diabetes over decades), and the ability to create cloned and genetically modified pigs in a short time [ 3 , 4 ]. However, the transplantation of pig cells, tissues, and organs may not only save and prolong human life, it may also be associated with the transmission of potentially zoonotic porcine microorganisms, and the porcine cytomegalovirus (PCMV) among them [ 5 , 6 ]. PCMV is widely distributed among pigs; it is a rather stable DNA virus that can easily be transmitted from pig to pig by milk, urine, and faeces [ 7 , 8 ]. Transplacental transmission of PCMV has also been described [ 8 , 9 ]. When evaluating the risk posed by PCMV, it was found that the survival time of pig kidneys from PCMV-infected pigs transplanted into baboons [ 10 ] or cynomolgus monkeys [ 11 ] was significantly reduced, indicating that PCMV may also pose a risk for clinical xenotransplantation [ 12 – 14 ]. The transmission of PCMV was also observed after pig heart transplantation, which was associated with injury of the transplant, and an increased incidence of consumptive coagulopathy [ 15 ]. Early weaning excluded PCMV, resulted in a prolonged survival of the transplant, and prevented consumptive coagulopathy [ 15 ].
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The porcine virome and xenotransplantation

The porcine virome and xenotransplantation

antibiotics and antimycotics, transmission of viruses through xenotransplantation may lead to disease in the recipient, i.e. zoonoses [28]. For most porcine viruses there are neither antivirals nor vaccines available. How- ever, it is still unclear whether porcine viruses can actu- ally infect humans and cause zoonoses. In contrast to human pathogens that are well adapted to humans, por- cine microorganisms are not. For only a few porcine vi- ruses a zoonotic potential has been described, for example for HEV, genotype 3. HEV induces a chronic infection in immunosuppressed patients and severe dis- ease in patients with a pre-existing liver failure (for re- view see [29, 30]). Of special interest is the porcine cytomegalovirus (PCMV) which may be indirectly pathogenic without infecting cells of the host. In preclin- ical trials of transplanting pig kidneys into cynomolgus monkeys and baboons, the presence of PCMV led to early transplant failure (for review see [31]). Since there is still no evidence for PCMV infection of non-human primate as well as human cells, the organ failure was possibly due to cytokines produced in response to viral antigens [31].
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Gene expression of inflammation markers in cardiac xenotransplantation

Gene expression of inflammation markers in cardiac xenotransplantation

Hyperacute rejection is the first immunologic barrier for transplantation between human or NHP and pig. It starts immediately when the pig coronary arteries are perfused by primate blood. The graft is destroyed within 24 hours, but often even within the first hour: primate blood contains "natural" anti-pig antibodies that bind the vascular endothelial cells of the pig heart and activate the complement cascade. This leads to immediate injury of the endothelium, which causes thrombosis in vessels and edema that disrupts the function of the endothelium and heart within minutes [10]. The rejection is caused by the interaction between a carbohydrate epitope, galactose-α1,3-galactose (Gal), from porcine endothelial cells and antibodies present in the primate blood[11]. During neonatal life of all primates, these antibodies develop and are probably a reaction to micro-organisms that colonize the gastrointestinal tract [12, 13]. This response is similar to that in ABO-incompatible allotransplantation rejections [14].
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Transmission of Hormonal Imprinting in Tetrahymena Cultures by Intercellular Communication 

Transmission of Hormonal Imprinting in Tetrahymena Cultures by Intercellular Communication 

Tetrahymena, H orm onal Im printing, Cell-to-Cell Comm unication T he prim ary interaction of cultured Tetrahymena cells with a horm one (insulin in the present case) gives rise to horm onal im printing, which accounts for a considerable increase in the later horm one binding capacity of the cells. Mixed culturing of im printed and not im printed (virgin) cells results in transm ission to the latter of the inform ation m ediated by im printing and thereby in a considerable increase in horm one binding capacity over that of pure horm one-preexposed cell cultures. The m aterial substrate of intercellular inform ation transmission is a cellular secretion which appears in the nutrient m edium , and is increasingly released in presence of not im printed (virgin) cells in the mixed culture.
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Ultrasonic Velocity and Absorption in 3 Melts Measured by the Pulse Transmission Method 

Ultrasonic Velocity and Absorption in 3 Melts Measured by the Pulse Transmission Method 

The apparatus is essentially improved, and the vol­ ume of the furnace is 75% smaller compared to the one used in [5]. The temperature errors amount to about 0.25 K in the cover of the furnace and to about 0.1 K in the melt. The lower quartz rod, together with the cell, is held in a PVC-mounting on a bracket below the furnace. The upper quartz rod is positioned in an adjustable aluminium block, which is held by a micro­ manipulator type HS 6 (Bachofer GmbH). Thus the inclination of the upper rod can be precisely adjusted so that the front sides of the transmitter and the re­ ceiver are parallel. The micromanipulator has a reso­ lution of 1 jim and allows a precise control of the upper quartz rod in the three space coordinates. So both rods can be aligned to minimize measuring er­ rors in the sound intensity. The mounting plate of the lower quartz rod is connected only to the frame of the apparatus at the equilibrated support. In that way the distance between the upper and lower piezoelectric quartz is maintained stationary even in case of ther­ mal variations in the set-up, so that errors in the dis­ tance determination are reliably avoided.
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Knockdown of porcine endogenous retrovirus (PERV) expression by PERV-specific shRNA in transgenic pigs

Knockdown of porcine endogenous retrovirus (PERV) expression by PERV-specific shRNA in transgenic pigs

The pLVTHM-pol2-transduced fibroblasts were cultured in vitro prior to being used for the production of transgenic pigs via somatic cell nuclear transfer. After activation, 115 cloned embryos were transferred surgically into the oviducts of one synchronized recipient. Pregnancy was confirmed by ultrasound scanning on days 25 and 35 after embryo transfer. After 116 days of gestation seven piglets were born; one of them was stillborn. None of the piglets showed any malformations. Mean birth weight was 1.3 kg which is similar to that of non-transgenic piglets in our pig facility. Ear biopsies were obtained from six piglets and frozen in liquid nitrogen. Four piglets died soon after birth due to agalactia of the sow. Following repeated application of 2 ml oxytocin (Oxytocin 10 IE/ml; Pharma Partner, Hamburg, Germany) lactation was reinitiated and two piglets survived. They were killed by barbiturate overdose at day 3, and samples of heart, lungs, spleen, liver, kidney, pancreas as well as muscle were taken and frozen in liquid nitrogen for further analysis. Control animals were produced by nuclear transfer using primary fibroblasts from non-transduced porcine fibroblasts P1 F10. At day 89 of gestation, organs of five animals were obtained by Caesarian section, the fetuses had a mean weight of 1.1 kg.
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Comparative anatomy of the pig brain : an integrative magnetic resonance imaging (MRI) study of the porcine brain with special emphasis on the external morphology of the cerebral cortex

Comparative anatomy of the pig brain : an integrative magnetic resonance imaging (MRI) study of the porcine brain with special emphasis on the external morphology of the cerebral cortex

It is known that the level of cortical gyrification varies across mammals of different brain sizes but very little is known about the influences triggering the emergence of the special pattern of grooves and ridges in the brain (Stark 1954). In the ferret (the smallest laboratory animal with a folded cortex) the gyrus formation was studied by firstly investigating the external features of the pallium during the folding process and secondly by describing the histological changes occurring within a gyrus as it develops and grows. It was observed that gyri are formed by longitudinal and radial expansion of the cortical department. Gyri occur between relatively fixed areas which form the sulcal floor. The hemispheres are also subjected to moulding by the growing skull. During that process the frontal pole of the cerebrum becomes pointed while the sulcal walls become closely opposed and the gyral crowns flattened (Smart and Mc Sherry 1986 a, Smart and Mc Sherry 1986 b). Pillay and Manger (2007) examined 25 different mammalian species and support the theory that, with increasing brain size and size of the mammal (actual mass of the periphery serviced by CNS), the gyrencephaly increases (Kuhlenbeck 1927, Stark 1982, Welker 1990, Nieuwenhuys et al. 1998, Danckers 2003). They also found ungulates to be the mammals with the most gyrencephalic brains. When species of similar brain weights were compared ungulate brains were significantly more gyrencephalic. It also seems to be the fact that large brains tend to be more convoluted than small brains due to the disproportionately small changes in cortical thickness (Hofman 1985). Minipigs, when kept under appropriate conditions (e.g. restrictive feeding) remain small, while a fully grown wild boar or landrace pig are larger in size and weight. Allometric growth doesn’t seem to contribute to the emergence of additional cortical areas or a significantly different organisation of the system of gyri and sulci (Fig. 63, Fig. 64-67). This study shows that within the suidae only few differences exist.
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Establishment and characterization of a size-reduced, diabetic pig model by minipig crossbreeding

Establishment and characterization of a size-reduced, diabetic pig model by minipig crossbreeding

of pigs of this strain confirmed normal synthesis and storage of insulin and a normal number of islets and β-cells. Therefore, “low K” pigs were not able to secrete an appropriate insulin amount due to an insufficient glucose stimulus. The secretory response of insulin to a glucose stimulus was reduced compared to other secretagogues like isoproterenol (Phillips, Panepinto et al. 1982, Panepinto and Phillips 1986). Females revealed a propensity for obesity and developed diabetes with hyperglycemia and hyperinsulinemia during gestation and lactation. Until the 7 th generation the characteristic of glucose intolerance got lost and the “low K” line is not available anymore (Hand, Surwit et al. 1987). Currently, the Yucatan minipig is used as a model for diabetes and dyslipidemia by inducing diabetes through STZ or alloxan and additionally obesity can be induced by feeding a high-fat diet. Besides hyperglycemia, these minipigs exhibited elevated cholesterol and triglyceride levels and obtained a normal to obese body shape. The acquired glycemic control and the body shape of these minipigs depended on the long-term insulin and food maintenance algorithm that was given to prevent diabetes- induced body wasting (Boullion, Mokelke et al. 2003). Furthermore, alloxan-induced diabetic male Yucatan pigs fed an atherogenic diet developed atherosclerosis and altered collagen depots in arteries (Hill, Dixon et al. 2001). Alloxan-induced diabetic animals showed retinal capillary changes, therefore it is a useful model for diabetes-associated microvascular alterations (Hainsworth, Katz et al. 2002). The Yucatan minipig is also a common model for exercise physiology and its effect on vascular function or lipoproteins (Mokelke, Dietz et al. 2005, Richardson, Lai et al. 2009). Yucatan models with a modified low-density lipoprotein receptor (LDLR) gene were generated, exhibiting hypercholesterolemia and a progressive atherosclerosis with formation of macrovascular lesions, especially when fed a high-fat diet (Davis, Wang et al. 2014, Amuzie, Swart et al. 2016). Selective breeding brought forth a Yucatan model with ventricular septal defect (VSD) (Sinclair-Bio-Resources 2019). The defect is very similar to the most common form of VSD in humans and some pigs additionally developed pulmonary hypertension and a patent foramen ovale (Swindle, Thompson et al. 1990). Furthermore, the Yucatan minipig is used in numerous fields of biomedical research,
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Xenotransplantation — A special case of One Health

Xenotransplantation — A special case of One Health

The methods developed for xenotransplantation to screen pig donors and human recipients can also be used to screen pigs bred for meat pro- duction. The prevalence of some viruses is very high in most pig popula- tions. For viruses causing economically important diseases in pigs, such as porcine reproductive and respiratory syndrome virus (PRRSV) and PCV2, sensitive detection methods and effective vaccines have been developed und successfully employed [62] . There may be viruses and other microor- ganisms present in the pigs which obviously do not harm the pig, but may be zoonotic for the human recipient, for example PCMV and HEV. 85% of pigs in a slaughterhouse in the Berlin area were found to be PCMV-positive [63] . HEV is a good example that pig viruses can be easily transmitted to humans and that they therefore pose a risk for xenotrans- plantation [14,64,65] . Pigs are infected with HEV genotype (gt) 3 and gt4 [14,64 –66] (not to be confused with HEV gt1 and gt2, which are only found in humans and which can cause infections with fatalities ap- proaching 25% in pregnant women). The main route of infection with HEV gt3 is food-borne transmission, e.g., contact with contaminated meat, or by direct contact with infected animals [67 –72] , by shell fish [73,74] ,but also by vegetables (probably contaminated with pig manure) [75] , blood transfusion [76 –78] and allotransplantation [79 –82] . Most in- fections with HEV gt3 and gt4 are asymptomatic, whereas severe hepati- tis occurs only in combination with other pre-existing chronic liver diseases. In addition, chronic infection with HEV is more likely to develop in profoundly immunosuppressed patients, for example during chemo- therapy [83] and HIV infection [84,85] . Patients undergoing xenotrans- plantation will certainly require immunosuppression. In Germany, the HEV seroprevalence of domestic pigs varied between 42.7% and 64.8% [86,87] , and genomic HEV RNA was found in 22% of pig liver sausages (al- though
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Valiant Hearts: The Great War

Valiant Hearts: The Great War

eingesetzt worden.35 Auch die Frankfurter Allgemeine Zeitung widmete dem Spiel einen Testbericht. Die Autorin fragt sich, warum jetzt erst mit Valiant Hearts ein Spiel erscheint, das das Interesse der Gamer-Community am Ersten Weltkrieg bedient, ohne dabei die Würde der Opfer zu verletzen. Der Artikel lobt besonders die vielen kleinen Details, etwa, dass Freddie bei seinem Eintritt in die französi- sche Fremdenlegion von seinen Kameraden wegen seiner Hautfarbe zunächst mit Obst beworfen wird. Der Kunstgriff, dass es sich bei den Charakteren um einfache Menschen handle, erlaube es, echte Zeugnisse, etwa Briefe, ins Geschehen ein- zubauen, schreibt die Autorin weiter. Zusammenfassend sagt sie, dass das Spiel sehr verantwortungsbewusst mit seinem historischen Hintergrund umgehe und dabei die spielerischen Aspekte nicht aus den Augen verliere.36 Auch die Professo- rin Angela Schwarz widmete dem Spiel einen kurzen Artikel. Sie beschreibt es als eine Form der „erzählenden Erinnerung an den Weltkrieg“. Ihrer Meinung nach sind es besonders „die Vielzahl und Auswahl der in Valiant Hearts zusammen- geführten Mittel, die es möglich machen, die Geschichte vielstimmig zu erzählen, ein Erinnern im Sinne eines Gedenkens an die Bedingungen im Krieg und die Op- fer zu ermöglichen, indem vom Ersten Weltkrieg im Computerspiel einmal ande- re Aspekte jenseits des bloßen Kämpfens sichtbar gemacht werden“.37
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Reassociation of Lactic Dehydrogenase from Pig Heart Studied by Cross-Linking with Glutaraldehyde 

Reassociation of Lactic Dehydrogenase from Pig Heart Studied by Cross-Linking with Glutaraldehyde 

Reconstitution o f porcine heart lactic dehydro­ genase after acid dissociation in the presence of 0.8 m N a2S 0 4 shows a strikingly sim ilar reassociation pattern (Fig. 5). As in the case o f the isoenzyme from skeletal muscle, only dim ers are found as interm ediates o f reconstitution; these m ust be formed in a rapid reaction during the transfer to reconstitu­ tion conditions. The association o f the interm ediary dim ers into tetram ers is found to be the rate-lim it­ ing step in the overall process o f reconstitution. Since a certain am ount o f m onom ers is present throughout the whole reconstitution reaction, a dissociation-association equilibrium between dimers and monomers is suggested.
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Transmission topologies for the integration of renewable power into the electricity systems of North Africa

Transmission topologies for the integration of renewable power into the electricity systems of North Africa

Transmission topologies for the integration of renewable power into the electricity systems of North Africa. In: Energy Policy, vol.[r]

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Incorporation of a Voltage Sensitive Pore from Guinea Pig Heart Mitochondria into Black Lipid Membranes and Characterization of Electrical Properties 

Incorporation of a Voltage Sensitive Pore from Guinea Pig Heart Mitochondria into Black Lipid Membranes and Characterization of Electrical Properties 

potential across the outer mitochondrial membrane is also imaginable. In the presence o f a transmem­ brane potential, the studied pore from guinea-pig heart mitochondria likely regulates permeation across this membrane by changing inner diameter. Especially C a2+, even in small amounts, could affect the pore size within the outer membrane through saturation of negative charges located on the inner side of this membrane. Numerous cationic binding sites of phospholipid nature with preference for divalent cations are known to exist in cardiac submitochondrial particles [21].
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Intergenerational transmission of education: The relative importance of transmission channels

Intergenerational transmission of education: The relative importance of transmission channels

correspond to the age when people are normally in secondary (including high school) and tertiary education. As for the simple correlation, I find differences between the two age groups. In general, the coefficients are slightly higher for the older group. A sharp increase is observed for the effect of mother’s education. The model fit also increases substantially from the younger the older age group. As for the simple correlations presented before, there are several possible explanations. First, it could be argued that this is due to a more precise measure of the dependent variable for the older age group. The second explanation is that the inequalities in education are a cumulative process and that the relative importance of the channels can evolve with the age of the child. Most likely both phenomena are present in these results. The fact that all indicators become more important supports the idea that the measurement is more precise for the older group. However, the fact that not all explanatory variables increase their effect in the same way points to something beyond this argument. In particular, the coefficient of the mother’s education increases substantially more than that of the others. Hence, we might have reasons to believe that the impact of the mother becomes more important with age. This could be due to the role of the mother in pushing the child to continue at school. Of course, additional research is required to confirm this conclusion, because the results could also be driven by the larger precision of the dependent variable.
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Correlation transmission of spiking neurons is boosted by synchronous input

Correlation transmission of spiking neurons is boosted by synchronous input

Schultze-Kraft, Matthias ; Diesmann, Markus ; Grün, Sonja ; Helias, Moritz : Correlation transmission of spiking neurons is boosted by synchronous input : From Twentieth Annual Computational Neuroscience Meeting: CNS*2011 Stockholm, Sweden. 23-28 July 2011. - In: BMC Neuroscience. - ISSN 1471-2202 (online). - 12 (2011), suppl. 1, P144. - doi:10.1186/1471-2202-12-S1-P144.

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Metabolie Conversions of Trichothecene Mycotoxins: Biotransformation of 3-AcetyldeoxynivaIenoI into Fusarenon-X 

Metabolie Conversions of Trichothecene Mycotoxins: Biotransformation of 3-AcetyldeoxynivaIenoI into Fusarenon-X 

In view of the variety of natural trichothecenes known, and the frequently complex mixture of struc­ tures produced by a single organism, it is probable that hydroxylase and esterase enzymes employed by these fungi have relatively low specificities with re­ spect to substrate. If so, it may be possible to exploit such enzymes to carry out specific biotransforma­ tions on a variety of different trichothecene sub­ strates, thus extending access to mycotoxin materials and allowing more detailed toxicological evaluations. We report here the feasibility of this approach by demonstrating the microbiological transformation of 3-acetyldeoxynivalenol (3-AcDON) (4) into other DON esters and also into the 4-oxygenated deriva­ tive fusarenon-X (9).
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Generation of a tailored pig model of Duchenne muscular dystrophy

Generation of a tailored pig model of Duchenne muscular dystrophy

sequencing approaches, such as the porcine genome are based on BAC libraries, providing a map of the pig genome and making BAC sequences accessible for various gene loci (CHEN et al., 2007; HUMPHRAY et al., 2007). BACs have been applied in several other fields of research in the mouse, like identification of mutation or characterization of regulatory sequences and functions of genes in vivo. Sequences adjacent to genes of interest on BACs may include genomic regulatory segments. Therefore, genes can be expressed under their own regulatory elements independent of their integration site, yet dependent on copy number and endogenous gene expression (CHANDLER et al., 2007). BACs are stable and easy to handle (GIRALDO & MONTOLIU, 2001), however, genetic modifications were difficult to achieve and screening by ordinary methods such as PCR and Southern blot is not possible due to the long homologous arms (VALENZUELA et al., 2003). Establishment of phage based recombination in E. coli made the modification of BAC sequences feasible and thus enabled the application of BACs in gene targeting experiments. There are two commonly used methods: ET cloning and recombineering (COPELAND et al., 2001; ZHANG et al., 1998). ET cloning uses the RecET system derived from the prophage Rac. Recombination is induced by addition of L-arabinose. Recombineering is accomplished by Red recombinase derived from bacteriophage λ, induced by heat shock. The development of screening methods for positively targeted cell clones by large vectors like the real-time PCR based “loss-of-native-allele” assay and applying the FISH assay made screening in BAC targeting experiments viable (VALENZUELA et al., 2003; YANG & SEED, 2003; GOMEZ-RODRIGUEZ et al., 2008). For the first time site-directed mutagenesis was successfully accomplished in murine ESCs (TESTA et al., 2003; VALENZUELA et al., 2003; YANG & SEED, 2003) and later on also in human ESCs (SONG et al., 2010). Effective targeting efficacies of up to 28% could be observed (YANG & SEED, 2003).
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Untersuchung transgener Tiermodelle für die Xenotransplantation

Untersuchung transgener Tiermodelle für die Xenotransplantation

Bei dem Caspase-abhängigen intrazellulären Signalweg, induziert durch TRAIL/TRAIL-Rezeptor- Interaktion, erfolgt über die Rekrutierung von zytoplasmatischen Proteinen an die Todesdomäne der Rezeptoren die Bildung des Apoptose-induzierenden Signalkomplexes (death-inducing signalling complex, DISC) (Kischkel et al. 2000; Sprick et al. 2000; Wang et al. 2001). Der DISC ist zentraler Bestandteil des Todesrezeptor-vermittelten Apoptosesignalwegs. Er enthält das Adapterprotein FADD (Fas-assoziierte Todesdomäne) und die Caspase-8 oder -10. Letztere werden durch proteolytische Spaltung aktiviert. Die Caspasen-8 und -10 sind Initiatorcaspasen der Apoptose, die das Apoptose- signal durch TRAIL an die weiter unten in der Signalkaskade liegenden ausführenden Caspasen (Caspasen-3, -6 und -7) durch deren proteolytische Spaltung und Aktivierung weiterleiten. Die Apoptose-ausführenden Caspasen bewirken dann die charakteristischen morphologischen Veränderungen einer apoptotischen Zelle, wie Schrumpfen, Kondensation und Fragmentierung von Chromatin im Zellkern und Veränderungen an der Zellmembran (Nicholson 1999). In einigen Zelltypen wird die TRAIL-induzierte Aktivierung der Caspase-3 durch die Einbeziehung des mitochondrialen Apoptosesignalwegs verstärkt (Deng et al. 2002; LeBlanc et al. 2002; Ravi & Bedi 2002; Kelley & Ashkenazi 2004). In diesen Fällen spalten und aktivieren die Caspasen-8 oder -10 Bid, ein pro- apoptotisches Mitglied der Bcl-2 Familie. Nach Aktivierung von zwei weiteren pro-apoptotischen Proteinen, Bax und Bak, durch Bid kommt es zur Freisetzung von apoptogenen Faktoren, wie Cytochrome C und Smac/DIABLO, aus dem Zytosol der Mitochondrien (Gong et al. 1999; Green & Evan 2002). Cytochrom C aktiviert, nach Bindung an Apaf-1 (apoptosis activating factor-1), die Initiatorprotease Caspase-9. Diese verstärkt die Aktivierung der Caspasen-3, -6 und -7. Smac/DIABLO bindet an Apoptoseinhibitoren (IAP) und verhindert dadurch, dass die IAP Caspase-3 inhibieren können. Dies führt ebenfalls zu einer weiteren Verstärkung der Caspase-3 Aktivierung.
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