2,912 research outputs found
Novel method for the isolation of adipose stem cells (ASCs)
Adipose stem cells (ASCs) represent a cell population with great potential for tissue engineering
applications. Several articles have been published showing the proliferation and differentiation
potential, the markers and the wide range of potential applications of these cells. In the majority
of these studies the ASCs are isolated using a basic enzymatic procedure, which results in a quite
heterogeneous cell population that compromises their proliferation and differentiation. This paper
reports the development and optimization of a new isolation/purification method that allows
populations of ASCs to be obtained, which significantly reduces (and eventually eliminates) the
‘contamination’ of other cell types. This method is based on the use of immunomagnetic beads
coated with specific antibodies. The first part of the study described here analysed the expression of
marker genes for stem cells and the colony-forming unit (CFU) capacity of the cells isolated, while
the second part is dedicated to the osteogenic differentiation potential of the isolated cells. The
results showed that, using the isolation method based on immunomagnetic beads, it was possible to
obtain ASCs and also underline the existence of several subpopulations of stem cells in the adipose
tissue
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Neuropsychological Test Performance and Other Predictors of Adult Outcome in a Prospective Follow-Up Study of Children with ADHD
The present research is a prospective follow-up study which investigates the neuropsychological test performance of children with Attention Deficit/Hyperactivity Disorder (ADHD) and examines whether test performance and severity of childhood disruptive behaviors predict adult psychiatric status and functioning in major domains (educational, social, and occupational). Participants were 100 middle-class, White boys (mean age = 9) of average intelligence diagnosed with ADHD without comorbid conduct disorder (CD) diagnoses. Childhood predictors were teacher behavioral ratings and performance on a variety of neuropsychological tests. Participants were later assessed at mean age 25 by clinicians blind to childhood status. Linear and logistic regression analyses were used to determine the impact of childhood predictor variables on adult outcome. Results showed no significant impairment on measures of neuropsychological functioning, nor was neuropsychological test performance generally correlated with severity of disruptive behaviors. ADHD boys with low ratings of conduct disorder behaviors (not at all, just a little) demonstrated lower verbal ability than those without CD behaviors. Severity of childhood CD behaviors emerged as the most consistent predictor of adult functioning and prevalence of psychiatric disorders. Measures of working memory and attention (Working Memory Index and Freedom from Distractibility Factor of the WISC-R) inconsistently predicted functioning in some areas, although this may reflect the well-known relationship between childhood IQ and later adult functioning. Taken together, the findings suggest that in boys with ADHD who are of average intelligence and have intact neuropsychological functioning, even low levels of CD behaviors are associated with poor prognosis in adulthood
Landsat TM and ETM+ derived snowline altitudes in the Cordillera Huayhuash and Cordillera Raura, Peru, 1986–2005
The Cordilleras Huayhuash and Raura are remote glacierized ranges in the Andes Mountains of Peru. A robust assessment of modern glacier change is important for understanding how regional change affects Andean communities, and for placing paleo-glaciers in a context relative to modern glaciation and climate. Snowline altitudes (SLAs) derived from satellite imagery are used as a proxy for modern (1986–2005) local climate change in a key transition zone in the Andes. <br><br> Clear sky, dry season Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) satellite images from 1986–2005 were used to identify snowline positions, and their altitude ranges were extracted from an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model (DEM). Based on satellite records from 31 glaciers, average snowline altitudes (SLAs), an approximation for the equilibrium line altitude (ELA), for the Cordillera Huayhuash (13 glaciers) and Cordillera Raura (18 glaciers) from 1986–2005 were 5051 m a.s.l. from 1986–2005 and 5006 m a.s.l. from 1986–2002, respectively. During the same time period, the Cordillera Huayhuash SLA experienced no significant change while the Cordillera Raura SLA rose significantly from 4947 m a.s.l. to 5044 m a.s.l
Inter-hemispheric linkages in climate change: paleo-perspectives for future climate change
The Pole-Equator-Pole (PEP) projects of the PANASH (Paleoclimates of the Northern and Southern Hemisphere) programme have significantly advanced our understanding of past climate change on a global basis and helped to integrate paleo-science across regions and research disciplines. PANASH science allows us to constrain predictions for future climate change and to contribute to the management of consequent environmental changes. We identify three broad areas where PEP science makes key contributions. 1. The pattern of global changes. Knowing the exact timing of glacial advances (synchronous or otherwise) during the last glaciation is critical to understanding interhemispheric links in climate. Work in PEPI demonstrated that the tropical Andes in South America were deglaciated earlier than the Northern Hemisphere (NH) and that an extended warming began there ca. 21 000 cal years BP. The general pattern is consistent with Antarctica and has now been replicated from studies in Southern Hemisphere (SH) regions of the PEPII transect. That significant deglaciation of SH alpine systems and Antarctica led deglaciation of NH ice sheets may reflect either i) faster response times in alpine systems and Antarctica, ii) regional moisture patterns that influenced glacier mass balance, or iii) a SH temperature forcing that led changes in the NH. This highlights the limitations of current understanding and the need for further fundamental paleoclimate research. 2. Changes in modes of operation of oscillatory climate systems. Work across all the PEP transects has led to the recognition that the El Niño Southern Oscillation (ENSO) phenomenon has changed markedly through time. It now appears that ENSO operated during the last glacial termination and during the early Holocene, but that precipitation teleconnections even within the Pacific Basin were turned down, or off. In the modern ENSO phenomenon both inter-annual and seven year periodicities are present, with the inter-annual signal dominant. Paleo-data demonstrate that the relative importance of the two periodicities changes through time, with longer periodicities dominant in the early Holocene. 3. The recognition of climate modulation of oscillatory systems by climate events. We examine the relationship of ENSO to a SH climate event, the Antarctic cold reversal (ACR), in the New Zealand region. We demonstrate that the onset of the ACR was associated with the apparent switching on of an ENSO signal in New Zealand. We infer that this related to enhanced zonal SW winds with the amplification of the pressure fields allowing an existing but weak ENSO signal to manifest itself. Teleconnections of this nature would be difficult to predict for future abrupt change as boundary conditions cannot readily be specified. Paleo-data are critical to predicting the teleconnections of future changes
Magnetic and thermodynamic properties of Sr_{2}LaFe_{3}O_{9}
Using a Dirac-Heisenberg Hamiltonian with biquadratic exchange interactions,
we study the effect of iron disproportionation on the magnetic ordering, and
describe the first-order magnetic transition occurring in the perovskite
Sr_{2}LaFe_{3}O_{9}. Upon fitting the experimental data, we give an estimate of
the exchange integrals for the antiferromagntic and ferromagnetic interactions,
in agreement with previous works on kindered compounds. Spin-wave theory yields
a magnon spectrum with a gapless antiferromagnetic mode together with two
gapped ferromagnetic ones.Comment: 8 pages of RevTex, 5 figures (available upon request), submitted to
J. Mag. Mag. Ma
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