4,846 research outputs found
'Special K' and a loss of cell-to-cell adhesion in proximal tubule-derived epithelial cells: modulation of the adherens junction complex by ketamine
Ketamine, a mild hallucinogenic class C drug, is the fastest growing ‘party drug’ used by 16–24 year olds in the UK. As the recreational use of Ketamine increases we are beginning to see the signs of major renal and bladder complications. To date however, we know nothing of a role for Ketamine in modulating both structure and function of the human renal proximal tubule. In the current study we have used an established model cell line for human epithelial cells of the proximal tubule (HK2) to demonstrate that Ketamine evokes early changes in expression of proteins central to the adherens junction complex. Furthermore we use AFM single-cell force spectroscopy to assess if these changes functionally uncouple cells of the proximal tubule ahead of any overt loss in epithelial cell function. Our data suggests that Ketamine (24–48 hrs) produces gross changes in cell morphology and cytoskeletal architecture towards a fibrotic phenotype. These physical changes matched the concentration-dependent (0.1–1 mg/mL) cytotoxic effect of Ketamine and reflect a loss in expression of the key adherens junction proteins epithelial (E)- and neural (N)-cadherin and β-catenin. Down-regulation of protein expression does not involve the pro-fibrotic cytokine TGFβ, nor is it regulated by the usual increase in expression of Slug or Snail, the transcriptional regulators for E-cadherin. However, the loss in E-cadherin can be partially rescued pharmacologically by blocking p38 MAPK using SB203580. These data provide compelling evidence that Ketamine alters epithelial cell-to-cell adhesion and cell-coupling in the proximal kidney via a non-classical pro-fibrotic mechanism and the data provides the first indication that this illicit substance can have major implications on renal function. Understanding Ketamine-induced renal pathology may identify targets for future therapeutic intervention
Relativistic cross sections of mass stripping and tidal disruption of a star by a super-massive rotating black hole
[abbreviated] We consider the problem of tidal disruption of a star by a
super-massive Kerr black hole. Using a numerically fast Lagrangian model of the
tidally disrupted star we survey the parameter space of the problem and find
the regions in the parameter space where the total disruption of the star or a
partial mass loss take place as a result of fly-by around the black hole. Our
treatment is based on General Relativity, and we consider the range of the
black hole masses where the tidal disruption competes with the relativistic
effect of direct capture of the star by the black hole. We find that our
results can be represented on the plane of specific orbital angular momenta of
the star . We calculate the contours of a given mass
loss of the star on this plane, referred to as the tidal cross sections, for a
given black hole mass , rotational parameter and inclination of the
trajectory of the star with respect to the black hole equatorial plane. It is
shown that the tidal cross sections can be approximated as circles symmetric
above the axis , and shifted with respect to the origin of the
coordinates in direction of negative . The radii and shifts of
these circles are obtained numerically for the black hole masses in the range
and different values of . It is
shown that when the tidal disruption takes place for and when the tidal disruption is possible for .Comment: 11 pages, 16 figures, A&A in press, the text is clarified, the title
and the abstract shown in text are change
Superfluid turbulence and pulsar glitch statistics
Experimental evidence is reviewed for the existence of superfluid turbulence
in a differentially rotating, spherical shell at high Reynolds numbers
(\Rey\gsim 10^3), such as the outer core of a neutron star. It is shown that
torque variability increases with \Rey, suggesting that glitch activity in
radio pulsars may be a function of \Rey as well. The \Rey distribution of
the 67 glitching radio pulsars with characteristic ages {\rm
yr} is constructed from radio timing data and cooling curves and compared with
the \Rey distribution of all 348 known pulsars with {\rm
yr}. The two distributions are different, with a Kolmogorov-Smirnov probability
. The conclusion holds for (modified) Urca and
nonstandard cooling, and for Newtonian and superfluid viscosities
Graded-bandgap AlGaAs solar cells for AlGaAs/Ge cascade cells
Some p/n graded-bandgap Al(x)Ga(1-x)As solar cells were fabricated and show AMO conversion efficiencies in excess of 15 percent without antireflection (AR) coatings. The emitters of these cells are graded between 0.008 is less than or equal to x is less than or equal to 0.02 during growth of 0.25 to 0.30 micron thick layers. The keys to achieving this performance were careful selection of organometallic sources and scrubbing oxygen and water vapor from the AsH3 source. Source selection and growth were optimized using time-resolved photoluminescence. Preliminary radiation-resistance measurements show AlGaAs cells degraded less than GaAs cells at high 1 MeV electron fluences, and AlGaAs cells grown on GaAs and Ge substrates degrade comparably
UAV mapping of rhizoctonia bare patch for targeted treatment
Rhizoctonia patches can be easily identified on both normal (RGB) and NDVI images captured by UAV. Mapping shows the pattern of patch distribution across a paddock, highlighting areas of crop with high and low levels of rhizoctonia patches
The Evolution of Blue Stragglers Formed Via Stellar Collisions
We have used the results of recent smoothed particle hydrodynamic simulations
of colliding stars to create models appropriate for input into a stellar
evolution code. In evolving these models, we find that little or no surface
convection occurs, precluding angular momentum loss via a magnetically-driven
stellar wind as a viable mechanism for slowing rapidly rotating blue stragglers
which have been formed by collisions. Angular momentum transfer to either a
circumstellar disk (possibly collisional ejecta) or a nearby companion are
plausible mechanisms for explaining the observed low rotation velocities of
blue stragglers. Under the assumption that the blue stragglers seen in NGC 6397
and 47 Tuc have been created solely by collisions, we find that the majority of
these blue stragglers cannot have been highly mixed by convection or meridional
circulation currents at anytime during their evolution. Also, on the basis of
the agreement between the predictions of our non-rotating models and the
observed blue straggler distribution, the evolution of blue stragglers is
apparently not dominated by the effects of rotation.Comment: 36 pages, including 1 table and 7 postscript figures (LaTeX2e). Also
avaliable at http://astrowww.phys.uvic.ca/~ouellet/ . Accepted for
publication in A
Prevalence, Trends and Associated Socio-Economic Factors of Obesity in South Asia
Aim: Worldwide obesity levels have increased unprecedentedly over the past couple of decades. Although the prevalence, trends and associated socio-economic factors of the condition have been extensively reported in Western populations, less is known regarding South Asian populations. Methods: A review of articles using Medline with combinations of the MeSH terms: 'Obesity', ‘Overweight’ and ‘Abdominal Obesity’ limiting to epidemiology and South Asian countries. Results: Despite methodological heterogeneity and variation according to country, area of residence and gender, the most recent nationally representative and large regional data demonstrates that without any doubt there is an epidemic of obesity, overweight and abdominal obesity in South Asian countries. Prevalence estimates of overweight and obesity (based on Asian cut-offs: overweight ≥ 23 kg/m[superscript]2, obesity ≥ 25 kg/m[superscript]2) ranged from 3.5% in rural Bangladesh to over 65% in the Maldives. Abdominal obesity was more prevalent than general obesity in both sexes in this ethnic group. Countries with the lowest prevalence had the highest upward trend of obesity. Socio-economic factors associated with greater obesity in the region included female gender, middle age, urban residence, higher educational and economic status. Conclusion: South Asia is significantly affected by the obesity epidemic. Collaborative public health interventions to reverse these trends need to be mindful of many socio-economic constraints in order to provide long-term solutions
Stress analysis of V-notches with and without cracks, with application to foreign object damage
Published versio
Calibration and evaluation of optical systems for full-field strain measurement
The design and testing of a reference material for the calibration of optical systems for strain measurement is described, together with the design and testing of a standardized test material that allows the evaluation and assessment of fitness for purpose of the most sophisticated optical system for strain measurement. A classification system for the steps in the measurement process is also proposed and allows the development of a unified approach to diagnostic testing of components or sub-systems in an optical system for strain measurement based on any optical technique. The results described arise from a European study known as SPOTS whose objectives were to begin to fill the gap caused by a lack of standards
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