147 research outputs found
Onderzoeksresultaten gestrande witsnuitdolfijn te Wijk aan Zee: Pathologie, dieet en plastic
No full textOp 7 december 2017 werd in de ochtend een gestrande dode witsnuitdolfijn (Lagenorhynchus albirostris) te Wijk aan Zee ontdekt. De Minister van het Ministerie van Landbouw, Natuur en Voedselkwaliteit (LNV) is verantwoordelijk voor de invulling van internationale verplichtingen en afspraken omtrent de biodiversiteit en de bescherming van in het wild levende bedreigde diersoorten. Vanuit die verantwoordelijkheid is er door het Ministerie van LNV een onderzoeksopdracht uitbesteed naar de strandingsoorzaak en herkomst van deze dolfijn. Strandingsonderzoek vindt in Nederland sinds 2008 plaats bij het Departement Pathobiologie van de Faculteit Diergeneeskunde van de Universiteit Utrecht met als hoofddoel het vaststellen van doodsoorzaken en hierbinnen het onderscheidt tussen natuurlijke en antropogene oorzaken. Daarnaast worden weefsels verzameld waarmee aanvullende onderzoeken kunnen worden uitgevoerd. Hieronder valt onder andere onderzoek naar dieet en plastics. Deze onderzoeken worden respectievelijk uitgevoerd door Wageningen Marine Research (WMR) en Bureau Waardenburg (BuWa). De gestrande witsnuitdolfijn was een volwassen mannelijk dier van 10 jaar oud. De witsnuitdolfijn was waarschijnlijk levend gestrand te Wijk aan Zee. Het dier was in een zeer goede voedingstoestand ten tijden van stranding. De laatste maaltijd van deze dolfijn bestond voornamelijk uit twee prooisoorten: wijting en zandspiering. Hoewel de tweede wellicht secundaire prooi was, vormde de wijting prooimassa duidelijk de belangrijkste prooisoort voor deze witsnuitdolfijn. Het dieet had een gereconstrueerde massa van ruim 19 kg vis. Dit was 6,84% van het gewicht van de dolfijn zelf, terwijl een dolfijn van deze omvang gemiddeld per dag ongeveer de helft van deze hoeveelheid moet eten. Er werd geen plastic in de maag en darm aangetroffen. Op basis van het postmortaal onderzoek kon worden vastgesteld dat de deze witsnuitdolfijn hoogstwaarschijnlijk acuut is overleden door een bacteriemie en sepsis (bloedvergiftiging) door bacteriële infectie met Clostridium sordelli. Dit resulteerde in hersen schade, shock, en uiteindelijk de dood
E2F Transcription Factors Control the Roller Coaster Ride of Cell Cycle Gene Expression
No full textInitially, the E2F transcription factor was discovered as a factor able to bind the adenovirus E2 promoter and activate viral genes. Afterwards it was shown that E2F also binds to promoters of nonviral genes such as C-MYC and DHFR, which were already known at that time to be important for cell growth and DNA metabolism, respectively. These findings provided the first clues that the E2F transcription factor might be an important regulator of the cell cycle. Since this initial discovery in 1987, several additional E2F family members have been identified, and more than 100 targets genes have been shown to be directly regulated by E2Fs, the majority of these are important for controlling the cell cycle.The progression of a cell through the cell cycle is accompanied with the increased expression of a specific set of genes during one phase of the cell cycle and the decrease of the same set of genes during a later phase of the cell cycle. This roller coaster ride, or oscillation, of gene expression is essential for the proper progression through the cell cycle to allow accurate DNA replication and cell division. The E2F transcription factors have been shown to be critical for the temporal expression of the oscillating cell cycle genes.This review will focus on how the oscillation of E2Fs and their targets is regulated by transcriptional, post-transcriptional and post-translational mechanism in mammals, yeast, flies, and worms. Furthermore, we will discuss the functional impact of E2Fs on the cell cycle progression and outline the consequences when E2F expression is disturbed
Inhibition of Salmonella-induced IL-8 synthesis and expression of Hsp70 in enterocyte-like Caco-2 cells after exposure to non-starter lactobacilli
No full textOral administration of lactobacilli as probiotics is gaining importance in the treatment of intestinal inflammations. We investigated the effect of non-starter lactobacilli Lactobacillus casei subsp casei 2756, Lactobacillus curvatus 2775, and Lactobacillus plantarum 2142 as well as their spent culture supernatants (SCS) on Salmonella enteritidis 857 growth, interleukin (IL)-8 and heat shock protein 70 (Hsp70) synthesis in undifferentiated crypt-like and differentiated villus-like Caco-2 cells. The cells were infected with graded numbers of non-starter lactobacilli or S. enteritidis 857 for 1 h and allowed to recover for 24 h or exposed to 200 bacteria/cell for 1 h and allowed to recover for different periods of time. In another experiment S. enteritidis 857 was first pre-treated with SCS-lactobacilli for 1 h before infecting the cells. The levels of IL-8 and Hsp70 were assessed using sandwich ELISA and immunostaining of Western blots, respectively. The effect of SCS-lactobacilli on S. enteritidis 857 growth was evaluated by agar plate diffusion test. The non-starter lactobacilli induced a significant increase in the levels of both IL-8 and Hsp70. However, compared with the S. enteritidis 857 induced IL-8 synthesis, the levels of IL-8 induced by the lactobacilli at any equivalent bacterial number were far lower. After exposure of Caco-2 cells to S. enteritidis 857 pre-treated with SCS-lactobacilli, it appeared that their SCS inhibited the S. enteritidis 857 growth and IL-8 synthesis and in addition induced the expression of Hsp70. The differences in response of crypt- and villus-like Caco-2 cells are merely a reflection of their differentiation status. Our data suggest that the beneficial effect of non-starter lactobacilli to the intestinal inflammations might be associated with a decrease of the IL-8 levels. This effect could be mediated, at least in part, by the bacteria themselves or via a secreted antimicrobial product(s) either directly against the pathogens or indirectly through the synthesis of Hsp70
Differential regulation of porcine beta-defensins 1 and 2 upon Salmonella infection in the intestinal epithelial cell line IPI-2I
No full textIntestinal epithelial cells represent the first line of defence against pathogenic bacteria in the lumen of the gut. Besides acting as a physical barrier, epithelial cells orchestrate the immune response through the production of several innate immune mediator molecules including beta-defensins. Here, we establish the porcine intestinal cell line IPI-2I as a new model system to test the regulation of porcine beta-defensins 1 and 2. Gene expression of both defensins was highly upregulated by foetal calf serum components in normal growth medium. In serum-free medium, baseline expression remained low, but pBD-2 gene expression was increased 10-fold upon infection with Salmonella Typhimurium. Arcobacter cryaerophilus and Salmonella Enteritidis, pathogenic bacteria with comparable adhesion and invasion characteristics, failed to increase pBD-2 mRNA levels. Heat killed or colistin-treated Salmonella Typhimurium had no effect, showing that the upregulation of pBD-2 was dependent on the viability of the Salmonella Typhimurium. Gene expression of pBD-1 was regulated differently since an increase in pBD-1 mRNA was observed by Salmonella Enteritidis infection. We conclude that the IPI-2I cells can serve as a new model to study porcine beta-defensin regulation and that pBD-1 and pBD-2 are differentially regulated in this cell line
Comparison of the in vitro pathogenicity of two Salmonella Typhimurium phage types
No full textThe in vitro pathogenicity of Salmonella enterica serovar Typhimurium phage type (pt) 90 and pt 506 (also known as DT 104) isolates from human and porcine origin was studied in adhesion and invasion assays to the human cell line Caco-2 and the porcine cell line IPI-2. Interleukin-8 (IL-8) production by these two cell lines in response to stimulation by the two Salmonella phage types was also measured. Generally, Salmonella Typhimurium pt 506 and pt 90 adhered to and invaded Caco-2 cells and IPI-2 cells equally well. The release of IL-8 by Caco-2 cells or by IPI-2 cells was similar, independent of the Salmonella phage type used for stimulation of the cells. These data suggest that Salmonella Typhimurium pt 90 has a similar ability to cause Salmonella infections as Salmonella Typhimurium DT 104
Concise Review: Organoids Are a Powerful Tool for the Study of Liver Disease and Personalized Treatment Design in Humans and Animals
No full textOrganoids are three-dimensional culture systems in which adult stem cells and their progeny grow and represent the native physiology of the cells in vivo. Organoids have been successfully derived from several organ systems in both animal models and human patients. Organoids have been used for fundamental research, disease modeling, drug testing, and transplantation. In this review, we summarize the applications of liver-derived organoids and discuss their potential. It is likely that organoids will provide an invaluable tool to unravel disease mechanisms, design novel (personalized) treatment strategies, and generate autologous stem cells for gene editing and transplantation purposes
Modelling dynamics and function of bone marrow cells in mouse liver regeneration
No full textIn rodents and humans the liver can restore its mass after hepatectomy efficiently. This is largely attributed to the proliferation and cell cycle re-entry of hepatocytes. On the other hand, bone marrow cells (BMCs) migrate into the liver after resection. Here we find that a block of BMC recruitment into the liver severely impairs its regeneration after the surgery. Mobilized hematopoietic stem and progenitor cells (HSPCs) in the resected liver can fuse with hepatocytes and the hybrids proliferate earlier than the hepatocytes. Genetic ablation of the hybrids severely impairs hepatocyte proliferation and liver mass regeneration. Mathematical modelling reveals a key role of BM-derived hybrids to drive proliferation in the regeneration process, and predicts regeneration efficiency in experimentally nontestable conditions. In conclusion, BM-derived hybrids are essential to trigger efficient liver regeneration after hepatectomy
Molecular pathways of senescence regulate placental structure and function
No full textThe placenta is an autonomous organ that maintains fetal growth and development. Its multinucleated syncytiotrophoblast layer, providing fetal nourishment during gestation, exhibits characteristics of cellular senescence. We show that in human placentas from pregnancies with intrauterine growth restriction, these characteristics are decreased. To elucidate the functions of pathways regulating senescence in syncytiotrophoblast, we used dynamic contrast-enhanced MRI in mice with attenuated senescence programs. This approach revealed an altered dynamics in placentas of p53(-/-), Cdkn2a(-/-), and Cdkn2a(-/-);p53(-/-) mice, accompanied by histopathological changes in placental labyrinths. Human primary syncytiotrophoblast upregulated senescence markers and molecular pathways associated with cell-cycle inhibition and senescence-associated secretory phenotype. The pathways and components of the secretory phenotype were compromised in mouse placentas with attenuated senescence and in human placentas from pregnancies with intrauterine growth restriction. We propose that molecular mediators of senescence regulate placental structure and function, through both cell-autonomous and non-autonomous mechanisms.</p
The Influence of Different Fat Sources on Steatohepatitis and Fibrosis Development in the Western Diet Mouse Model of Non-alcoholic Steatohepatitis (NASH)
No full textNon-alcoholic steatohepatitis (NASH) is the leading cause of chronic liver injury and the third most common reason for liver transplantations in Western countries. It is unclear so far how different fat sources in Western diets (WD) influence the development of NASH. Our study investigates the impact of non-trans fat (NTF) and corn oil (Corn) as fat source in a WD mouse model of steatohepatitis on disease development and progression. C57BL/6J wildtype (WT) mice were fed “standard” WD (WD-Std), WD-NTF or WD-Corn for 24 weeks. WT animals treated with WD-NTF exhibit distinct features of the metabolic syndrome compared to WD-Std and WD-Corn. This becomes evident by a worsened insulin resistance and elevated serum ALT, cholesterol and triglyceride (TG) levels compared to WD-Corn. Animals fed WD-Corn on the contrary tend to a weakened disease progression in the described parameters. After 24 weeks feeding with WD-NTF and WD-Std, WD-Corn lead to a comparable steatohepatitis initiation by histomorphological changes and immune cell infiltration compared to WD-Std. Immune cell infiltration results in a significant increase in mRNA expression of the pro-inflammatory cytokines IL-6 and TNF-α, which is more pronounced in WD-NTF compared to WD-Std and WD-Corn. Interestingly the fat source has no impact on the composition of accumulating fat within liver tissue as determined by matrix-assisted laser desorption/ionization mass spectrometry imaging of multiple lipid classes. The described effects of different fat sources on the development of steatohepatitis finally resulted in variations in fibrosis development. Animals treated with WD-NTF displayed massive collagen accumulation, whereas WD-Corn even seems to protect from extracellular matrix deposition. Noteworthy, WD-Corn provokes massive histomorphological modifications in epididymal white adipose tissue (eWAT) and severe accumulation of extracellular matrix which are not apparent in WD-Std and WD-NTF treatment. Different fat sources in WD-Std contribute to strong steatohepatitis development in WT mice after 24 weeks treatment. Surprisingly, corn oil provokes histomorphological changes in eWAT tissue. Accordingly, both WD-NTF and WD-Corn appear suitable as alternative dietary treatment to replace “standard” WD-Std as a diet mouse model of steatohepatitis whereas WD-Corn leads to strong changes in eWAT morphology
Contributions of the S2 spike ectodomain to attachment and host range of infectious bronchitis virus
No full textThe spike protein is the major viral attachment protein of the avian coronavirus infectious bronchitis virus (IBV) and ultimately determines viral tropism. The S1 subunit of the spike is assumed to be required for virus attachment. However, we have previously shown that this domain of the embryo- and cell culture adapted Beaudette strain, in contrast to that of the virulent M41 strain, is not sufficient for binding to chicken trachea (Wickramasinghe et al., 2011). In the present study, we demonstrated that the lack of binding of Beaudette S1 was not due to absence of virus receptors on this tissue nor due to the production of S1 from mammalian cells, as S1 proteins expressed from chicken cells also lacked the ability to bind IBV-susceptible embryonic tissue. Subsequently, we addressed the contribution of the S2 subunit of the spike in IBV attachment. Recombinant IBV Beaudette spike ectodomains, comprising the entire S1 domain and the S2 ectodomain, were expressed and analyzed for binding to susceptible embryonic chorio-allantoic membrane (CAM) in our previously developed spike histochemistry assay. We observed that extension of the S1 domain with the S2 subunit of the Beaudette spike was sufficient to gain binding to CAM. A previously suggested heparin sulfate binding site in Beaudette S2 was not required for the observed binding to CAM, while sialic acids on the host tissues were essential for the attachment. To further elucidate the role of S2 the spike ectodomains of virulent IBV M41 and chimeras of M41 and Beaudette were analyzed for their binding to CAM, chicken trachea and mammalian cell lines. While the M41 spike ectodomain showed increased attachment to both CAM and chicken trachea, no binding to mammalian cells was observed. In contrast, Beaudette spike ectodomain had relatively weak ability to bind to chicken trachea, but displayed marked extended host range to mammalian cells. Binding patterns of chimeric spike ectodomains to these tissues and cells indicate that S2 subunits most likely do not contain an additional independent receptor-binding site. Rather, the interplay between S1 and S2 subunits of spikes from the same viral origin might finally determine the avidity and specificity of virus attachment and thus viral host range
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