1,721,063 research outputs found
Adult liver stem cells in hepatic regeneration and cancer
No full textAn alternative source of livers for transplantation in patients with (genetic) liver diseases and liver failure is needed because liver donors are scarce. HPC-derived hepatocyte-like cells could be one of the options. Because dogs and humans share liver-pathologies and disease-pathways, the dog is considered the best model for human liver disease. We can use dogs to test safety and efficacy of a new treatment before considering to apply it in human clinics. We developed the long-term culture system of adult canine hepatic progenitor cells in three-dimensions, called organoids. Canine liver organoids showed characteristics of stem cells, cholangiocytes and hepatocytes, mimicking in vivo liver progenitor cell phenotype, and had potential to differentiate towards functional hepatocytes. Organoids derived from COMMD1-deficient dogs presented a copper excretion defect similar to the in vivo situation in dogs with copper storage disease. Upon transduction with a COMMD1 construct, successful restoration of copper excretion was achieved. Patient-derived liver organoids are a powerful tool to perform disease modeling and demonstrate the feasibility to perform gene correction in liver organoids, a key prerequisite for autologous transplantation for gene-therapy. Upon liver injury either hepatocytes themselves or progenitor cells proliferate to regenerate the liver. However, in many virus-induced liver diseases and cancers the hepatocytes harbor mutations in the tumor suppressor genes, Rb and p53. Therefore the regenerative response may differ from regeneration under normal situations. We analyzed the cooperative role of Rb and p53 in accordance with the 3, 5-diethoxycarbonyl-1, 4-dihydrocollidine (DDC) diet, a xenobiotic inducing hepatobiliary injury and oval cell proliferation. DDC is metabolized by Cyp3a. Deletion of both Rb and p53 deregulates Cyp3a activity causing less porphyrin accumulation, therefore mild oval cell proliferation is induced. In addition, Rb/p53 deficient livers experience less biliary injury, but instead more hepatocellular injury under DDC exposure. Finally, inactivation of Rb/p53 shortens life span and accelerates HCC development after DDC exposure. Rb and p53 are not only important cell cycle regulators, but also influence xenobiotic metabolism of cells. Liver resection and radiofrequency ablation (RFA) are the treatment of choice for liver cancers. Yet, cancer recurrence rate after resection is high. We focused on identifying the mechanism of liver tumor formation after surgical interventions. Partial hepatectomy and RFA were performed in mice with p53 and Rb-specific deletion in the livers. Cancer developed at the necrotic injury site, and cancer initiation was associated with migration, expansion, and transformation of bile duct cells within the injury site. This resulted in the formation of undifferentiated carcinomas. A necrotic environment induced by surgery combined with loss of tumor suppressor genes causes liver cancer and epithelial-mesenchymal transition at the surgery site. Bile duct cells or HPCs are the cell-of-origin of liver tumors in this model. Polyploidization is a normal physiological event for livers. Atypical E2Fs, especially E2F8, are essential for hepatocyte binucleation and polyploidization. E2F8 inactivation resulted in up-regulation of E2F-target genes promoting DNA replication, DNA repair, mitosis and cytokinesis. Prevention of polyploidization through inactivation of atypical E2Fs did not have any impact on liver differentiation, zonation, metabolism and regeneration
Serum alpha1-proteinase inhibitor concentrations in healthy dogs - method validation and determination of reference interval and intra-individual variation
No full textBackground A chronic loss of canine 1-proteinase inhibitor (c1-PI) into the gastrointestinal (GI) tract could change the systemic proteinase-proteinase inhibitor balance. Serum c1-PI concentrations have not been studied in dogs with well-defined GI diseases. Objectives To further evaluate serum c1-PI concentrations in dogs with GI diseases, the objectives of this study were to (1) analytically validate a previously developed fecal c1-PI immunoassay to determine serum concentrations, (2) determine a population-based reference interval (RI) and assess the clinical utility, (3) determine stability of serum c1-PI, (4) determine the intra-individual variation in healthy dogs, and (5) determine the clinically relevant magnitude of change of serum c1-PI. Methods Prestudy validation of the 125I-c1-PI immunoassay included linearity, spiking recovery, and intra- and inter-assay precision. A RI was calculated with samples of healthy dogs. Stability at -20 degrees C was tested on 36 samples. Intra-individual variation was assessed using samples collected from 11 healthy dogs over a 12-week period. Results The c1-PI radioimmunoassay (RIA) was linear, accurate, precise, and reproducible. Serum c1-PI decreased by 11% after oneyear at -20 degrees C. Analytical, intra-individual, inter-individual, and total variation were 6.4, 9.9, 9.0, and 25.3%, respectively. The RI for serum c1-PI was 732-1802mg/L (n=87); there were no differences between sex and age groups. The index of individuality was 1.31. As analytical variation was > 1/2 inter-individual variation, the minimum critical difference was not determined. Conclusions The results of this study provide the basis for further evaluating serum c1-PI in dogs with GI disease. Using a population-based RI for serum c1-PI appears to be appropriate
The role of DNA damage and inhibition of poly(ADP-ribosyl)ation in loss of clonogenicity of murine L929 fibroblasts, caused by photodynamically induced oxidative stress
No full textReactive oxygen species are used to eradicate malignant cells in photodynamic therapy as well as in other cancer therapies. Despite many efforts, the pathways leading to cellular damage and cell killing due to the action of these species are poorly understood. In previous studies with hematoporphyrin derivative-sensitized L929 murine fibroblasts, the only parameter for which a relation with photodynamically induced reproductive cell death could not be excluded was inhibition of DNA excision repair. The present results show that loss of clonogenicity of these cells in fact is related to a series of effects, including the development of slight, irreperable DNA damage, a virtually complete inhibition of poly(ADP-ribosyl)ation activation, a transient elevation of the intracellular calcium concentration and, after a lag time of about 8 h, DNA fragmentation caused by endonuclease activity. This conclusion is supported by the observation that photodynamic treatment inhibited the repair of X-ray-induced DNA strand breaks and suppressed X-ray- and methyl methanesulfonate-induced enhancement of poly(ADP-ribosyl)ation. Our experimental results further suggest that in this cell line the photodynamically induced inhibition of enhanced poly(ADP-ribosyl)ation could well be involved in inhibition of repair of DNA strand breaks and in activation of endonuclease activity
Highly sensitive pyrogen detection on medical devices by the monocyte activation test
No full textPyrogens are components of microorganisms, like bacteria, viruses or fungi, which can induce a complex inflammatory response in the human body. Pyrogen contamination on medical devices prior operation is still critical and associated with severe complications for the patients. The aim of our study was to develop a reliable test, which allows detection of pyrogen contamination on the surface of medical devices. After in vitro pyrogen contamination of different medical devices and incubation in a rotation model, the human whole blood monocyte activation test (MAT), which is based on an IL-1β-specific ELISA, was employed. Our results show that when combining a modified MAT protocol and a dynamic incubation system, even smallest amounts of pyrogens can be directly detected on the surface of medical devices. Therefore, screening of medical devices prior clinical application using our novel assay, has the potential to significantly reduce complications associated with pyrogen-contaminated medical devices
Follow-up of 100 dogs with acute diarrhoea in a primary care practice.
No full textThis study aimed to examine the aetiology of acute diarrhoea and the relapse rate in 100 client-owned dogs presented to a first-opinion clinic. History, physical examination, faecal testing and owner questionnaire data were collected at initial presentation (T0) and at either the time of relapse or at a recheck performed within 3 months. All dogs received treatment according to their clinical signs. Of 96 dogs that completed the study, 37 (38.5%) relapsed during the study period, 21 (21.9%) relapsed within 3 months, and 16 others (16.6%) at 3 months to 1 year after initial examination. Dogs that had undergone a change in housing location within 1 month prior to presentation and dogs <1 year old were significantly more likely to have positive parasitological analyses (P=0.02 and P=0.001, respectively). Pica was a risk factor for relapse (P=0.0002)
Hemocompatibility testing according to ISO 10993-4: Discrimination between pyrogen- and device-induced hemostatic activation
No full textNext to good hemocompatibility performance of new medical devices, which has to be tested according to the ISO 10993-4, the detection of pyrogen-contaminated devices plays a pivotal role for safe device application. During blood contact with pyrogen-contaminated devices, intense inflammatory and hemostatic reactions are feared. The aim of our study was to investigate the influence of pyrogenic contaminations on stents according to the ISO 10993-4. The pyrogens of different origins like lipopolysaccharides (LPS), purified lipoteichoic acid (LTA) or zymosan were used. These pyrogens were dried on stents or dissolved and circulated in a Chandler-loop model for 90 min at 37 degrees C with human blood. Before and after circulation, parameters of the hemostatic system including coagulation, platelets, complement and leukocyte activation were investigated. The complement system was activated by LPS isolated from Klebsiella pneumoniae and Pseudomonas aeruginosa and by LTA. Leukocyte activation was triggered by LPS isolated from K. pneumoniae, LTA and zymosan, whereas coagulation and platelet activation were only slightly influenced. Our data indicate that pyrogen-contaminated devices lead to an alteration in the hemostatic response when compared to depyrogenized devices. Therefore, pyrogenicity testing should be performed prior to hemocompatibility tests according to ISO 10993-4 in order to exclude hemostatic activation induced by pyrogen contaminations. (C) 2014 Elsevier B.V. All rights reserved
Redox unbalance in the hyperthyroid cat: a comparison with healthy and non-thyroidal diseased cats
Get PDFAbstract Background Feline hyperthyroidism, the most common endocrinopathy in older cats, provides a spontaneous model for human thyrotoxicosis. Human thyrotoxicosis is associated with redox unbalance, which may result in organ damage. The redox status of hyperthyroid cats is largely unknown. The aims of the present study were to compare the redox status of cats with hyperthyroidism with that of healthy cats and cats with chronic non-thyroidal illness. Results Forty cats with untreated hyperthyroidism (group H), 45 chronically ill cats with non-thyroidal illness (group I), and 39 healthy cats (group C) were recruited for this observational cross-sectional study. All cats were screened for redox status markers. Determinable reactive oxygen metabolites (d-ROMs) were used as oxidative stress markers. Antioxidant status was determined using the OXY-Adsorbent test to quantify the plasma barrier to oxidation. The Oxidative Stress index (OSi) was calculated as the ratio of d-ROMs and OXY-Adsorbent test values. Data were compared by ANOVA with Tukey’s multiple comparisons post-hoc test. The dROMs of group H (193 ± 47 CarrU) were significantly higher (p < 0.001) than those of the healthy cats (103 ± 17 CarrU). The OXY-Adsorbent test results in group H (265 ± 68 μmol HClO/ml) were significantly lower than those in healthy cats (390 ± 83 μmol HClO/ml; p < 0.01) and chronically ill cats (306 ± 45 μmol HClO/ml, p < 0.05). Moreover, the Osi value in group H (0.8 ± 0.2 CarrU/μmol HClO/ml) was significantly higher (p < 0.001) than that of the healthy cats (0.3 ± 0.1 CarrU/μmol HClO/ml). Conclusions As described in humans with hyperthyroidism, feline hyperthyroidism is associated with redox unbalance. Free radical production is increased in hyperthyroid cats and their antioxidant depletion seems to be more severe than in cats with non-thyroidal illnesses. Our results support the rationale for a clinical trial investigating the potential positive effects of antioxidant supplementation to cats with hyperthyroidism
Discovery of new feline paramyxoviruses in domestic cats with chronic kidney disease
Get PDFParamyxoviruses constitute a large family of enveloped RNA viruses including important pathogens in veterinary and human medicine. Recently, feline paramyxoviruses, genus morbillivirus, were detected in cats from Hong Kong and Japan. Here we describe the discovery of several new feline paramyxoviruses. Infections with these diverse viruses were detected in urine samples from cats suffering from chronic kidney disease (CKD). No viral RNA was found in cats without clinical signs of uropathy highlighting an association between feline paramyxovirus (FPaV) infections and CKD. Phylogenetic analyses of the detected viruses showed that they represent at least two different species, one of them representing the feline morbilliviruses detected previously in Hong Kong and Japan. In addition, a new FPaV was detected sharing only 73 % homology on the nucleotide level of the viral L-gene to currently known paramyxoviral species
Expression of steroidogenic factor 1 in canine cortisol-secreting adrenocortical tumors and normal adrenals
No full textWe report on a screening for the relative messenger RNA (mRNA) and protein expression of steroidogenic factor 1 (SF-1) in normal canine adrenals (n = 10) and cortisol-secreting adrenocortical tumors (11 adenomas and 26 carcinomas). The relative mRNA expression of SF-1 was determined by quantitative real-time polymerase chain reaction analysis and revealed no differences between normal adrenals, adenomas, and carcinomas. Immunohistochemistry demonstrated SF-1 protein expression in a nuclear pattern throughout the normal adrenal cortex and a predominantly nuclear staining pattern in adrenocortical tumors. Of the 15 dogs available for follow up, 7 dogs developed hypercortisolism within 2.5 yr after adrenalectomy, with metastatic disease in 6 dogs and adrenocortical tumor regrowth in 1 dog. The relative SF-1 mRNA expression in dogs with early recurrence was greater (2.46-fold, P = 0.020) than in dogs in remission for at least 2.5 yr after adrenalectomy. In conclusion, we demonstrated the presence of SF-1 expression in normal canine adrenals and adrenocortical tumors. The high SF-1 mRNA expression in carcinomas with early recurrence might indicate its value as a prognostic marker, as well as its potential for therapeutic development
Canine Models for Copper Homeostasis Disorders
No full textCopper is an essential trace nutrient metal involved in a multitude of cellular processes. Hereditary defects in copper metabolism result in disorders with a severe clinical course such as Wilson disease and Menkes disease. In Wilson disease, copper accumulation leads to liver cirrhosis and neurological impairments. A lack in genotype-phenotype correlation in Wilson disease points toward the influence of environmental factors or modifying genes. In a number of Non-Wilsonian forms of copper metabolism, the underlying genetic defects remain elusive. Several pure bred dog populations are affected with copper-associated hepatitis showing similarities to human copper metabolism disorders. Gene-mapping studies in these populations offer the opportunity to discover new genes involved in copper metabolism. Furthermore, due to the relatively large body size and long life-span of dogs they are excellent models for development of new treatment strategies. One example is the recent use of canine organoids for disease modeling and gene therapy of copper storage disease. This review addresses the opportunities offered by canine genetics for discovery of genes involved in copper metabolism disorders. Further, possibilities for the use of dogs in development of new treatment modalities for copper storage disorders, including gene repair in patient-derived hepatic organoids, are highlighted
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