162 research outputs found
Prenatal Testing for Adult‐Onset Conditions: the Position of the National Society of Genetic Counselors
Advances in genetic testing and the availability of such testing in pregnancy allows prospective parents to test their future child for adult‐onset conditions. This ability raises several complex ethical issues. Prospective parents have reproductive rights to obtain information about their fetus. This information may or may not alter pregnancy management. These rights can be in conflict with the rights of the future individual, who will be denied the right to elect or decline testing. This paper highlights the complexity of these issues, details discussions that went into the National Society of Genetic Counselors (NSGC) Public Policy Task Force’s development of the Prenatal testing for Adult‐Onset Conditions position statement adopted in November 2014, and cites relevant literature on this topic through December 2015. Issues addressed include parental rights and autonomy, rights of the future child, the right not to know, possible adverse effects on childhood and the need for genetic counseling. This paper will serve as a reference to genetic counselors and healthcare professionals when faced with this situation in clinical practice.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146906/1/jgc41139.pd
Observation of Collective-Emission-Induced Cooling inside an Optical Cavity
We report the observation of collective-emission-induced, velocity-dependent
light forces. One third of a falling sample containing 3 x 10^6 cesium atoms
illuminated by a horizontal standing wave is stopped by cooperatively emitting
light into a vertically oriented confocal resonator. We observe decelerations
up to 1500 m/s^2 and cooling to temperatures as low as 7 uK, well below the
free space Doppler limit. The measured forces substantially exceed those
predicted for a single two-level atom.Comment: 10 pages, 5 figure
Improved osteogenic vector for non-viral gene therapy
Therapeutic compensation of deficient bone regeneration is a challenging task and a topic of on-going search for novel treatment strategies. One promising approach for improvement involves non-viral gene delivery using the bone morphogenetic protein-2 (BMP-2) gene to provide transient, local and sustained expression of the growth factor. However, since efficiency of non-viral gene delivery is low, this study focused on the improvement of a BMP-2 gene expression system, aiming for compensation of poor transfection efficiency. First, the native BMP-2 gene sequence was modified by codon optimisation and altered by inserting a highly truncated artificial intron (96 bp). Transfection of multiple cell lines and rat adipose-derived mesenchymal stem cells with plasmids harbouring the improved BMP-2 sequence led to a several fold increased expression rate and subsequent osteogenic differentiation. Additionally, comparing expression kinetics of elongation factor 1 alpha (EF1α) promoter with a state of the art CMV promoter revealed significantly higher BMP-2 expression when under the influence of the EF1α promoter. Results obtained by quantification of bone markers as well as osteogenic assays showed reduced sensitivity to promoter silencing effects of the EF1α promoter in rat adipose-derived mesenchymal stem cells. Finally, screening of several protein secretion signals using either luciferase or BMP-2 as reporter protein revealed no superior candidates for potential replacement of the native BMP-2 secretion signal. Taken together, by enhancing the exogenous BMP-2 expression system, low transfection efficiencies in therapeutic applications can be compensated, making safe non-viral systems even more suitable for tissue regeneration approaches
On Two Models of the Light Pulse Delay in a Saturable Absorber
A comparative analysis of two approaches to description of the light
modulation pulse delay in a saturable absorber is presented. According to the
simplest model, the delay of the optical pulse is a result of distortion of its
shape due to absorption self-modulation in the nonlinear medium. The second
model of the effect, proposed at the beginning of our century, connects the
pulse delay with the so-called "slow light" resulting from the group velocity
reduction under conditions of the coherent population oscillations. It is shown
that all the known experimental data on the light pulse delay in saturable
absorbers can be comprehensively described in the framework of the simplest
model of saturable absorber and do not require invoking the effect of coherent
population oscillations with spectral hole-burning and anomalous modifications
of the light group velocity. It is concluded that the effect of group velocity
reduction under conditions of coherent population oscillations has not received
so far any experimental confirmation, and the assertions about real observation
of the "slow light" based on this mechanism are groundless.Comment: Regretfully, the journal version of the paper (in Optics and
Spectroscopy) appeared to be strongly corrupted due to ignorant editing. In
particular, "coherent population oscillations" (CPO) was replaced by
"population coherent oscillations" (PCO), "bleaching" - by "clearing", and
"bleachable absorber " - by "clearable absorber". Here we present original
version of the pape
Polarization instabilities in a two-photon laser
We describe the operating characteristics of a new type of quantum oscillator
that is based on a two-photon stimulated emission process. This two-photon
laser consists of spin-polarized and laser-driven K atoms placed in a
high-finesse transverse-mode-degenerate optical resonator, and produces a beam
with a power of 0.2 W at a wavelength of 770 nm. We observe
complex dynamical instabilities of the state of polarization of the two-photon
laser, which are made possible by the atomic Zeeman degeneracy. We conjecture
that the laser could emit polarization-entangled twin beams if this degeneracy
is lifted.Comment: Accepted by Physical Review Letters. REVTeX 4 pages, 4 EPS figure
Gas Dynamic Virtual Nozzle for Generation of Microscopic Droplet Streams
As shown by Ganan-Calvo and co-workers, a free liquid jet can be compressed
in iameter through gas-dynamic forces exerted by a co-flowing gas, obviating
the need for a solid nozzle to form a microscopic liquid jet and thereby
alleviating the clogging problems that plague conventional droplet sources of
small diameter. We describe in this paper a novel form of droplet beam source
based on this principle. The source is miniature, robust, dependable, easily
fabricated, and eminently suitable for delivery of microscopic liquid droplets,
including hydrated biological samples, into vacuum for analysis using vacuum
instrumentation. Monodisperse, single file droplet streams are generated by
triggering the device with a piezoelectric actuator. The device is essentially
immune to clogging
Spatiotemporal Differences in Gene Expression Between Motor and Sensory Autografts and Their Effect on Femoral Nerve Regeneration in the Rat
To improve the outcome after autologous nerve grafting in the clinic, it is important to understand the limiting variables such as distinct phenotypes of motor and sensory Schwann cells. This study investigated the properties of phenotypically different autografts in a 6 mm femoral nerve defect model in the rat, where the respective femoral branches distally of the inguinal bifurcation served as homotopic, or heterotopic autografts. Axonal regeneration and target reinnervation was analyzed by gait analysis, electrophysiology, and wet muscle mass analysis. We evaluated regeneration-associated gene expression between 5 days and 10 weeks after repair, in the autografts as well as the proximal, and distal segments of the femoral nerve using qRT-PCR. Furthermore we investigated expression patterns of phenotypically pure ventral and dorsal roots. We identified highly significant differences in gene expression of a variety of regeneration-associated genes along the central – peripheral axis in healthy femoral nerves. Phenotypically mismatched grafting resulted in altered spatiotemporal expression of neurotrophic factor BDNF, GDNF receptor GFRα1, cell adhesion molecules Cadm3, Cadm4, L1CAM, and proliferation associated Ki67. Although significantly higher quadriceps muscle mass following homotopic nerve grafting was measured, we did not observe differences in gait analysis, and electrophysiological parameters between treatment paradigms. Our study provides evidence for phenotypic commitment of autologous nerve grafts after injury and gives a conclusive overview of temporal expression of several important regeneration-associated genes after repair with sensory or motor graft
Rapid assessment of nonlinear optical propagation effects in dielectrics
Ultrafast laser processing applications need fast approaches to assess the nonlinear propagation of the laser beam in order to predict the optimal range of processing parameters in a wide variety of cases. We develop here a method based on the simple monitoring of the nonlinear beam shaping against numerical prediction. The numerical code solves the nonlinear Schrödinger equation with nonlinear absorption under simplified conditions by employing a state-of-the art computationally efficient approach. By comparing with experimental results we can rapidly estimate the nonlinear refractive index and nonlinear absorption coefficients of the material. The validity of this approach has been tested in a variety of experiments where nonlinearities play a key role, like spatial soliton shaping or fs-laser waveguide writing. The approach provides excellent results for propagated power densities for which free carrier generation effects can be neglected. Above such a threshold, the peculiarities of the nonlinear propagation of elliptical beams enable acquiring an instantaneous picture of the deposition of energy inside the material realistic enough to estimate the effective nonlinear refractive index and nonlinear absorption coefficients that can be used for predicting the spatial distribution of energy deposition inside the material and controlling the beam in the writing process
Resilient emotionality and molecular compensation in mice lacking the oligodendrocyte-specific gene Cnp1
Altered oligodendrocyte structure and function is implicated in major psychiatric illnesses, including low cell number and reduced oligodendrocyte-specific gene expression in major depressive disorder (MDD). These features are also observed in the unpredictable chronic mild stress (UCMS) rodent model of the illness, suggesting that they are consequential to environmental precipitants; however, whether oligodendrocyte changes contribute causally to low emotionality is unknown. Focusing on 2′-3′-cyclic nucleotide 3′-phosphodiesterase (Cnp1), a crucial component of axoglial communication dysregulated in the amygdala of MDD subjects and UCMS-exposed mice, we show that altered oligodendrocyte integrity can have an unexpected functional role in affect regulation. Mice lacking Cnp1 (knockout, KO) displayed decreased anxiety- and depressive-like symptoms (i.e., low emotionality) compared with wild-type animals, a phenotypic difference that increased with age (3–9 months). This phenotype was accompanied by increased motor activity, but was evident before neurodegenerative-associated motor coordination deficits (⩽9–12 months). Notably, Cnp1KO mice were less vulnerable to developing a depressive-like syndrome after either UCMS or chronic corticosterone exposure. Cnp1KO mice also displayed reduced fear expression during extinction, despite normal amygdala c-Fos induction after acute stress, together implicating dysfunction of an amygdala-related neural network, and consistent with proposed mechanisms for stress resiliency. However, the Cnp1KO behavioral phenotype was also accompanied by massive upregulation of oligodendrocyte- and immune-related genes in the basolateral amygdala, suggesting an attempt at functional compensation. Together, we demonstrate that the lack of oligodendrocyte-specific Cnp1 leads to resilient emotionality. However, combined with substantial molecular changes and late-onset neurodegeneration, these results suggest the low Cnp1 seen in MDD may cause unsustainable and maladaptive molecular compensations contributing to the disease pathophysiology
- …