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Search Results: 1 - 10 of 225017 matches for " Kevin C. Ess "
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Multi-organ Abnormalities and mTORC1 Activation in Zebrafish Model of Multiple Acyl-CoA Dehydrogenase Deficiency
Seok-Hyung Kim ,Sarah A. Scott,Michael J. Bennett,Robert P. Carson,Joshua Fessel,H. Alex Brown,Kevin C. Ess
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003563
Abstract: Multiple Acyl-CoA Dehydrogenase Deficiency (MADD) is a severe mitochondrial disorder featuring multi-organ dysfunction. Mutations in either the ETFA, ETFB, and ETFDH genes can cause MADD but very little is known about disease specific mechanisms due to a paucity of animal models. We report a novel zebrafish mutant dark xavier (dxavu463) that has an inactivating mutation in the etfa gene. dxavu463 recapitulates numerous pathological and biochemical features seen in patients with MADD including brain, liver, and kidney disease. Similar to children with MADD, homozygote mutant dxavu463 zebrafish have a spectrum of phenotypes ranging from moderate to severe. Interestingly, excessive maternal feeding significantly exacerbated the phenotype. Homozygous mutant dxavu463 zebrafish have swollen and hyperplastic neural progenitor cells, hepatocytes and kidney tubule cells as well as elevations in triacylglycerol, cerebroside sulfate and cholesterol levels. Their mitochondria were also greatly enlarged, lacked normal cristae, and were dysfunctional. We also found increased signaling of the mechanistic target of rapamycin complex 1 (mTORC1) with enlarged cell size and proliferation. Treatment with rapamycin partially reversed these abnormalities. Our results indicate that etfa gene function is remarkably conserved in zebrafish as compared to humans with highly similar pathological, biochemical abnormalities to those reported in children with MADD. Altered mTORC1 signaling and maternal nutritional status may play critical roles in MADD disease progression and suggest novel treatment approaches that may ameliorate disease severity.
Gammaretroviral vector encoding a fluorescent marker to facilitate detection of reprogrammed human fibroblasts during iPSC generation
Narasimhachar Srinivasakumar,Michail Zaboikin,Andrew M. Tidball,Asad A. Aboud,M. Diana Neely,Kevin C. Ess,Aaron B. Bowman,Friedrich G. Schuening
PeerJ , 2015, DOI: 10.7717/peerj.224
Abstract: Induced pluripotent stem cells (iPSCs) are becoming mainstream tools to study mechanisms of development and disease. They have a broad range of applications in understanding disease processes, in vitro testing of novel therapies, and potential utility in regenerative medicine. Although the techniques for generating iPSCs are becoming more straightforward, scientists can expend considerable resources and time to establish this technology. A major hurdle is the accurate determination of valid iPSC-like colonies that can be selected for further cloning and characterization. In this study, we describe the use of a gammaretroviral vector encoding a fluorescent marker, mRFP1, to not only monitor the efficiency of initial transduction but also to identify putative iPSC colonies through silencing of mRFP1 gene as a consequence of successful reprogramming.
The influence of stress on substrate utilization in skeletal muscle fibres of reindeer (Rangifer tarandus L)
B. Essén-Gustavsson,C. Rehbinder
Rangifer , 1984,
Abstract: Moderate stress in connection with handling, sampling and herding of reindeer caused a very pronounced depletion of glycogen in mainly type IIA and IIB fibres. Also intramuscular triglyceride levels decreased but mainly in type I fibres. Muscle lactate levéls increased in all animals but not to the levels found in pigs exposed to stress or exertion. Reindeer muscles appeared to have a great capacity to oxidize both carbohydrates and lipids. All animals showed increased Cortisol, urea and AS AT values. A marked depletion of glycogen and lipids in many of the fibres may be a factor involved in the development of skeletal muscle degeneration in connection with mental stress and exertion as there seems to be a correlation between high ASAT values and substrate depleted musclefibres. A connection may therefore exist between high instramuscular substrate stores and the ability of a muscle to tolerate stress. Av stress p verkat substratutnyttjande i skelettmuskelfibrer hos ren Abstract in Swedish / Sammanfattning: M ttlig stress betingad av hantering, provtagning och drivning av ren orsakade en mycket kraftig minskning av muskelglykogen i fr mst typ IIA och typ IIB fibrer. Aven triglycerider minskade framfor allt i typ I fibrer. Muskellaktatniv erna okade i samtliga undersokta djur, men inte till niv er som ses hos gris utsatta for stress eller fysisk anstr ngning.Renens muskler uppvisade en mycket hog kapacitet att oxidera, forbranna, b de kolhydrat och fett. Alla djur uppvisade forhojda Cortisol, urea och ASAT varden. Den mycket kraftiga tomningen av kolhydrat och fett i m nga muskelfibrer kan vara en faktor medverkande till muskeldegeneration i samband med mental stress och anstrangning d hoga ASAT-v rden synes vara korrelerade till uttomda muskelfibrer. Ett samband mellan hog instramuskul r substratupplagring och form ga att t la stress kan s ledes foreligga. Stressin vaikuttaneen poron substraattihyv k-sik ytto luurangon lihaksiston kuiduissa. Abstract in Finnish / Yhteenveto: Kohtuullinen stressi edellytt en k sittely , kokeenottoa ja poronajoa aiheutti hyvin voimakkaan lihasglykogeenin v hentymisen etenkin II A ja II B tyyppisiss fiibereiss . Myoskin triglyseriidit v hentyiv t kaikissa tutkituissa el imissa, muttei kuitenkaan niihin tasoihin asti kuin sijoissa, jotka ovat joutuneet alttiiksi stressiin tai fyysilliseen rasitukseen. porojen lihakset osoittivat hyvin korkeaa kapasiteettia sek hiilihydraatin ett rasvan palamiseen. Kaikki el imet osoittivat kohonnutta cortisoolin, urean ja ASATin arvoa. Hyvin voimakas hiilihydraatin ja rasvan tyhjentymin
Magnetic Field Expulsion from an Infinite Cylindrical Superconductor
Miguel C. N. Fiolhais,Hanno Essén
Physics , 2014, DOI: 10.1016/j.physc.2013.11.006
Abstract: The solutions of the London equations for the magnetic field expulsion from superconductors are presented in this paper for the cylindrical symmetry. The result is analyzed in detail and represented numerically for the case of a uniform external magnetic field in the transverse plane. In particular, several contour plots of the magnetic energy density are depicted for the regions inside and around the superconducting area for a wide range of penetration lengths, showing how the expulsion and penetration of the magnetic field evolve with the ratio between the penetration length and the cylinder radius.
Electromagnetic wave scattering by a superconductor
Miguel C. N. Fiolhais,Hanno Essén
Physics , 2012, DOI: 10.1209/0295-5075/97/44006
Abstract: The interaction between radiation and superconductors is explored in this paper. In particular, the calculation of a plane standing wave scattered by an infinite cylindrical superconductor is performed by solving the Helmholtz equation in cylindrical coordinates. Numerical results computed up to $\mathcal{O}(77)$ of Bessel functions are presented for different wavelengths showing the appearance of a diffraction pattern.
Electrodynamics of Perfect Conductors
Miguel C. N. Fiolhais,Hanno Essén
Physics , 2013, DOI: 10.1007/s10773-013-1491-9
Abstract: The most general electrodynamic equations of a perfect conducting state are obtained using a variational principle in a classical framework, following an approach by Pierre-Gilles de Gennes. London equations are derived as the time-independent case of these equations, corresponding to the magnetostatic minimal energy state of the perfect conducting system. For further confirmation, the same equations are also derived in the classical limit of the Coleman-Weinberg model, the most successful quantum macroscopic theory of superconductivity. The magnetic field expulsion is, therefore, a direct consequence of zero resistivity and not an exclusive property of superconductors.
The Physics of Rotational Flattening and the Point Core Model  [PDF]
Hanno Essén
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.56051
Abstract:

The effect of rotation on the shape (figure) and gravitational quadrupole of astronomical bodies is calculated by using an approximate point core model: A point mass at the center of an ellipsoidal homogeneous fluid. Maclaurin’s analytical result for homogenous bodies generalizes to this model and leads to very accurate analytical results connecting the three observables: oblateness (ò), gravitational quadrupole (J2), and angular velocity parameter (q). The analytical results are compared to observational data for the planets and a good agreement is found. Oscillations near equilibrium are studied within the model.

Autophagy Induction Is a Tor- and Tp53-Independent Cell Survival Response in a Zebrafish Model of Disrupted Ribosome Biogenesis
Yeliz Boglev,Andrew P. Badrock,Andrew J. Trotter,Qian Du,Elsbeth J. Richardson,Adam C. Parslow,Sebastian J. Markmiller,Nathan E. Hall,Tanya A. de Jong-Curtain,Annie Y. Ng,Heather Verkade,Elke A. Ober,Holly A. Field,Donghun Shin,Chong H. Shin,Katherine M. Hannan,Ross D. Hannan,Richard B. Pearson,Seok-Hyung Kim,Kevin C. Ess,Graham J. Lieschke,Didier Y. R. Stainier,Joan K. Heath
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003279
Abstract: Ribosome biogenesis underpins cell growth and division. Disruptions in ribosome biogenesis and translation initiation are deleterious to development and underlie a spectrum of diseases known collectively as ribosomopathies. Here, we describe a novel zebrafish mutant, titania (ttis450), which harbours a recessive lethal mutation in pwp2h, a gene encoding a protein component of the small subunit processome. The biochemical impacts of this lesion are decreased production of mature 18S rRNA molecules, activation of Tp53, and impaired ribosome biogenesis. In ttis450, the growth of the endodermal organs, eyes, brain, and craniofacial structures is severely arrested and autophagy is up-regulated, allowing intestinal epithelial cells to evade cell death. Inhibiting autophagy in ttis450 larvae markedly reduces their lifespan. Somewhat surprisingly, autophagy induction in ttis450 larvae is independent of the state of the Tor pathway and proceeds unabated in Tp53-mutant larvae. These data demonstrate that autophagy is a survival mechanism invoked in response to ribosomal stress. This response may be of relevance to therapeutic strategies aimed at killing cancer cells by targeting ribosome biogenesis. In certain contexts, these treatments may promote autophagy and contribute to cancer cells evading cell death.
Metabolism during anaesthesia and recovery in colic and healthy horses: a microdialysis study
Anna H Edner, Birgitta Essén-Gustavsson, G?rel C Nyman
Acta Veterinaria Scandinavica , 2009, DOI: 10.1186/1751-0147-51-10
Abstract: Ten healthy university-owned horses given anaesthesia alone and ten client-owned colic horses subjected to emergency abdominal surgery were anaesthetised for a mean (range) of 230 min (193–273) and 208 min (145–300) respectively. Venous blood samples were taken before anaesthesia. Venous blood sampling and microdialysis in the gluteal muscle were performed during anaesthesia and until 24 h after anaesthesia. Temporal changes and differences between groups were analysed with an ANOVA for repeated measures followed by Tukey Post Hoc test or Planned Comparisons.Lactate, glucose and urea, in both dialysate and plasma, were higher in the colic horses than in the healthy horses for several hours after recovery to standing. In the colic horses, lactate, glucose, and urea in dialysate, and lactate in plasma increased during the attempts to stand. The lactate-to-pyruvate ratio was initially high in sampled colic horses but decreased over time. In the colic horses, dialysate glycerol concentrations varied considerably whereas in the healthy horses, dialysate glycerol was elevated during anaesthesia but decreased after standing. In both groups, lactate concentration was higher in dialysate than in plasma. The correspondence between dialysate and plasma concentrations of glucose, urea and glycerol varied.Microdialysis proved to be suitable in the clinical setting for monitoring of the metabolic events during anaesthesia and recovery. It was possible with this technique to show greater muscle metabolic alterations in the colic horses compared to the healthy horses in response to regaining the standing position.Microdialysis as a means to repeatedly sample and analyze various substances in the interstitial fluid and in body cavities has enabled the study of local tissue metabolic events [1-7]. The great advantage with this technique is that it allows real-time monitoring of the metabolic events in local tissue with a minimum of trauma. When introduced into the tissue, the microdi
Metabolism before, during and after anaesthesia in colic and healthy horses
Anna H Edner, G?rel C Nyman, Birgitta Essén-Gustavsson
Acta Veterinaria Scandinavica , 2007, DOI: 10.1186/1751-0147-49-34
Abstract: 20 healthy horses given anaesthesia alone and 20 colic horses subjected to emergency abdominal surgery were anaesthetised for a mean of 228 minutes and 183 minutes respectively. Blood for analysis of haematology, electrolytes, cortisol, creatine kinase (CK), free fatty acids (FFA), glycerol, glucose and lactate was sampled before, during, and up to 7 days after anaesthesia. Arterial and venous blood gases were obtained before, during and up to 8 hours after recovery. Gluteal muscle biopsy specimens for biochemical analysis of muscle metabolites were obtained at start and end of anaesthesia and 1 h and 1 day after recovery.Plasma cortisol, FFA, glycerol, glucose, lactate and CK were elevated and serum phosphate and potassium were lower in colic horses before anaesthesia. Muscle adenosine triphosphate (ATP) content was low in several colic horses. Anaesthesia and surgery resulted in a decrease in plasma FFA and glycerol in colic horses whereas levels increased in healthy horses. During anaesthesia muscle and plasma lactate and plasma phosphate increased in both groups. In the colic horses plasma lactate increased further after recovery. Plasma FFA and glycerol increased 8 h after standing in the colic horses. In both groups, plasma concentrations of CK increased and serum phosphate decreased post-anaesthesia. On Day 7 most parameters were not different between groups. Colic horses lost on average 8% of their initial weight. Eleven colic horses completed the study.Colic horses entered anaesthesia with altered metabolism and in a negative oxygen balance. Muscle oxygenation was insufficient during anaesthesia in both groups, although to a lesser extent in the healthy horses. The post-anaesthetic period was associated with increased lipolysis and weight loss in the colic horses, indicating a negative energy balance during the first week post-operatively.An approximately ten-fold higher incidence of anaesthetic-related deaths has been reported in colic horses undergoing em
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