342 research outputs found
Is HIV short-sighted? Insights from a multistrain nested model
No full textAn important component of pathogen evolution at the population level is evolution within hosts. Unless evolution within hosts is very slow compared to the duration of infection, the composition of pathogen genotypes within a host is likely to change during the course of an infection, thus altering the composition of genotypes available for transmission as infection progresses. We develop a nested modeling approach that allows us to follow the evolution of pathogens at the epidemiological level by explicitly considering within-host evolutionary dynamics of multiple competing strains and the timing of transmission. We use the framework to investigate the impact of short-sighted within-host evolution on the evolution of virulence of human immunodeficiency virus (HIV), and find that the topology of the within-host adaptive landscape determines how virulence evolves at the epidemiological level. If viral reproduction rates increase significantly during the course of infection, the viral population will evolve a high level of virulence even though this will reduce the transmission potential of the virus. However, if reproduction rates increase more modestly, as data suggest, our model predicts that HIV virulence will be only marginally higher than the level that maximizes the transmission potential of the virus
Comparison of oxygen uptake during arm or leg cardiopulmonary exercise testing in vascular surgery patients and control subjects
No full textAmniotic fluid stem cells prevent development of ascites in a neonatal rat model of necrotizing enterocolitis.
No full textIt has been demonstrated that in a neonatal rat model of necrotizing enterocolitis (NEC), amniotic fluid stem (AFS) cells decrease intestinal damage and improve survival via modulation of stromal cells expressing cyclooxygenase 2 in the lamina propria. Herein, we aimed to evaluate the effect of AFS cells on body weight and fluid retention in this NEC model. Methods AFS cells were obtained from green fluorescent protein (GFP) + pregnant rats at E16 and expanded in culture. A total of 185 neonatal rats had NEC induced by gavage feeding of hypertonic formula + hypoxia + oral lipopolysaccharide (4 mg/kg/d) and were randomized to intraperitoneal phosphate buffered saline (PBS, n = 93) or AFS cells (n = 92). A total of 36 breastfed (BF) rats were used as controls. All rats were being killed at 96 hours of life. Groups were compared for body weight and presence of free intraperitoneal fluid using nonparametric and contingency tests. Data are expressed as mean ± standard deviation. There were no differences in birth weight among the groups (PBS = 5.6 ± 0. 3 g; AFS cells = 5.6 ± 0. 3 g; BF = 5.6 ± 0. 3 g; p = 1). The body weight at randomization was not different between PBS (5.61 ± 0. 5 g) and AFS cells (5.60 ± 0. 5; p = 1) rats. After the rats were killed, BF rats were significantly heavier (12.5 ± 0.1 g) than PBS (5.12 ± 0.4 g) and AFS cell rats (4.95 ± 0.3; p < 0.0001). From randomization to being killed, PBS rats had 9% of weight loss in comparison with 12% in AFS cell rats (p = 0.08). After the rats were killed, 42 (45%) PBS rats developed ascites with evident abdominal distension in comparison with 19 (21%) AFS cells (p = 0.0005). None of BF animals had ascites. Gavage feeding and undernutrition severely affect growth in this model of NEC. Administration of AFS cells result in lower incidence of ascites than in PBS rats. This could explain the differences in body weight between the two groups of rats that were killed. Furthermore, studies on liver function and fluid composition are needed to investigate our speculation. Georg Thieme Verlag KG Stuttgart · New York
Multifunctional receptor-targeted nanocomplexes for magnetic resonance imaging and transfection of tumours.
No full textThe efficient targeted delivery of nucleic acids in vivo provides some of the greatest challenges to the development of genetic therapies. We aim to develop nanocomplex formulations that achieve targeted transfection of neuroblastoma tumours that can be monitored simultaneously by MRI. Here, we have compared nanocomplexes comprising self-assembling mixtures of liposomes, plasmid DNA and one of three different peptide ligands derived from ApoE, neurotensin and tetanus toxin for targeted transfection in vitro and in vivo. Neurotensin-targeted nanocomplexes produced the highest levels of transfection and showed a 4.7-fold increase in transfected luciferase expression over non-targeted nanocomplexes in Neuro-2A cells. Transfection of subcutaneous Neuro-2A tumours in vivo with neurotensin-targeted nanocomplexes produced a 9.3-fold increase in gene expression over non-targeted controls. Confocal microscopy analysis elucidated the time course of DNA delivery with fluorescently labelled nanocomplex formulations in cells. It was confirmed that addition of a gadolinium lipid conjugate contrast agent allowed real time in vivo monitoring of nanocomplex localisation in tumours by MRI, which was maintained for at least 24 h. The peptide-targeted nanocomplexes developed here allow for the specific enhancement of targeted gene therapy both in vitro and in vivo, whilst allowing real time monitoring of delivery with MRI
Nubian a-group and Egyptian Naqada trade relations in the predynastic
No full textThe archaeological study of interregional trade provides the unique opportunity to reconstruct not only the foreign relations of cultures that are no longer in existence, but also how these relations evolved over extended periods of time. This study examines interactions between the Egyptian Naqada and Nubian A-Group cultures - located near the present day border of Egypt and The Sudan - between 3800 and 2900 B.C.E. Cemeteries from each group were compared looking at frequency of grave goods, burial architecture, the treatment of the deceased, and how these factors changed over time, in order to determine: (a) the degree of social complexity in Nubian A-Group society, and (b) the ability of trade to influence culture. The study found that while Nubian A-Group society shows some signs of social complexity, the A-Group culture was not nearly as complex as the near state-level society seen with the Egyptian Naqada culture. In line with this, the study found that there was a disproportionate level of cultural influence between the two groups, with the Nubian A-Group culture adopting many Egyptian traits
Glutamate Dysfunction in People with Prodromal Symptoms of Psychosis: Relationship to Gray Matter Volume
No full textBackground: The glutamate model of schizophrenia proposes that altered glutamatergic neurotransmission is fundamental to the development of the disorder. In addition, its potential to mediate neurotoxicity raises the possibility that glutamate dysfunction could underlie neuroanatomic changes in schizophrenia. Here we determine whether changes in brain glutamate are present in subjects at ultra high risk of developing psychosis and whether these changes are related to reductions in cortical gray matter volume. Methods: Twenty-seven individuals with an at-risk mental state and a group of 27 healthy volunteers underwent proton magnetic resonance spectroscopy and volumetric proton magnetic resonance imaging using a 3-Tesla scanner. Glutamate and glutamine levels were measured in anterior cingulate, left hippocampus, and left thalamus. These measures were then related to cortical gray matter volume. Results: At-risk mental state (ARMS) subjects had significantly lower levels of glutamate than control subjects in the thalamus (p < .05) but higher glutamine in the anterior cingulate (p < .05). Within the ARMS group, the level of thalamic glutamate was directly correlated with gray matter volume in the medial temporal cortex and insula (p < .01). Conclusions: This study provides the first evidence that brain glutamate function is perturbed in people with prodromal signs of schizophrenia and that glutamatergic dysfunction is associated with a reduction in gray matter volume in brain regions thought to be critical to the pathogenesis of the disorder. These findings support the hypothesis that drugs affecting the glutamate system may be of benefit in the early stages of psychotic illness. © 2009 Society of Biological Psychiatry
Amniotic fluid stem cells improve survival and enhance repair of damaged intestine in necrotising enterocolitis via a COX-2 dependent mechanism.
No full textNecrotising enterocolitis (NEC) remains one of the primary causes of morbidity and mortality in neonates and alternative strategies are needed. Stem cells have become a therapeutic option for other intestinal diseases, which share some features with NEC. We tested the hypothesis that amniotic fluid stem (AFS) cells exerted a beneficial effect in a neonatal rat model of NEC. Rats intraperitoneally injected with AFS cells and their controls (bone marrow mesenchymal stem cells, myoblast) were analysed for survival, behaviour, bowel imaging (MRI scan), histology, bowel absorption and motility, immunofluorescence for AFS cell detection, degree of gut inflammation (myeloperoxidase and malondialdehyde), and enterocyte apoptosis and proliferation. AFS cells integrated in the bowel wall and improved rat survival and clinical conditions, decreased NEC incidence and macroscopic gut damage, improved intestinal function, decreased bowel inflammation, increased enterocyte proliferation and reduced apoptosis. The beneficial effect was achieved via modulation of stromal cells expressing cyclooxygenase 2 in the lamina propria, as shown by survival studies using selective and non-selective cyclooxygenase 2 inhibitors. Interestingly, AFS cells differentially expressed genes of the Wnt/β-catenin pathway, which regulate intestinal epithelial stem cell function and cell migration and growth factors known to maintain gut epithelial integrity and reduce mucosal injury. We demonstrated here for the first time that AFS cells injected in an established model of NEC improve survival, clinical status, gut structure and function. Understanding the mechanism of this effect may help us to develop new cellular or pharmacological therapies for infants with NEC
In vitro and in vivo cardiomyogenic differentiation of amniotic fluid stem cells.
No full textCell therapy has developed as a complementary treatment for myocardial regeneration. While both autologous and allogeneic uses have been advocated, the ideal candidate has not been identified yet. Amniotic fluid-derived stem (AFS) cells are potentially a promising resource for cell therapy and tissue engineering of myocardial injuries. However, no information is available regarding their use in an allogeneic context. c-kit-sorted, GFP-positive rat AFS (GFP-rAFS) cells and neonatal rat cardiomyocytes (rCMs) were characterized by cytocentrifugation and flow cytometry for the expression of mesenchymal, embryonic and cell lineage-specific antigens. The activation of the myocardial gene program in GFP-rAFS cells was induced by co-culture with rCMs. The stem cell differentiation was evaluated using immunofluorescence, RT-PCR and single cell electrophysiology. The in vivo potential of Endorem-labeled GFP-rAFS cells for myocardial repair was studied by transplantation in the heart of animals with ischemia/reperfusion injury (I/R), monitored by magnetic resonance imaging (MRI). Three weeks after injection a small number of GFP-rAFS cells acquired an endothelial or smooth muscle phenotype and to a lesser extent CMs. Despite the low GFP-rAFS cells count in the heart, there was still an improvement of ejection fraction as measured by MRI. rAFS cells have the in vitro propensity to acquire a cardiomyogenic phenotype and to preserve cardiac function, even if their potential may be limited by poor survival in an allogeneic setting
A rat decellularized small bowel scaffold that preserves villus-crypt architecture for intestinal regeneration.
No full textManagement of intestinal failure remains a clinical challenge and total parenteral nutrition, intestinal elongation and/or transplantation are partial solutions. In this study, using a detergent-enzymatic treatment (DET), we optimize in rats a new protocol that creates a natural intestinal scaffold, as a base for developing functional intestinal tissue. After 1 cycle of DET, histological examination and SEM and TEM analyses showed removal of cellular elements with preservation of the native architecture and connective tissue components. Maintenance of biomechanical, adhesion and angiogenic properties were also demonstrated strengthen the idea that matrices obtained using DET may represent a valid support for intestinal regeneration
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