204 research outputs found
DNA copy number loss and allelic imbalance at 2p16 in lung cancer associated with asbestos exposure
Five to seven percent of lung tumours are estimated to occur because of occupational asbestos exposure. Using cDNA microarrays, we have earlier detected asbestos exposure-related genomic regions in lung cancer. The region at 2p was one of those that differed most between asbestos-exposed and non-exposed patients. Now, we evaluated genomic alterations at 2p22.1-p16.1 as a possible marker for asbestos exposure. Lung tumours from 205 patients with pulmonary asbestos fibre counts from 0 to 570 million fibres per gram of dry lung, were studied by fluorescence in situ hybridisation (FISH) for DNA copy number alterations (CNA). The prevalence of loss at 2p16, shown by three different FISH probes, was significantly increased in lung tumours of asbestos-exposed patients compared with non-exposed (P=0.05). In addition, a low copy number loss at 2p16 associated significantly with high-level asbestos exposure (P=0.02). Furthermore, 27 of the tumours were studied for allelic imbalances (AI) at 2p22.1–p16.1 using 14 microsatellite markers and also AI at 2p16 was related to asbestos exposure (P=0.003). Our results suggest that alterations at 2p16 combined with other markers could be useful in diagnosing asbestos-related lung cancer
Non-invasive Estimation of Metabolic Uptake Rate of Glucose using F18-FDG PET and Linear Transformation of Outputs
Coronal emission from the shocked circumstellar ring of SN 1987A
High resolution spectra with UVES/VLT of SN 1987A from December 2000 until
November 2005 show a number of high ionization lines from gas with velocities
of roughly 350 km/s, emerging from the shocked gas formed by the ejecta-ring
collision. These include coronal lines from [Fe X], [Fe XI] and [Fe XIV] which
have increased by a factor of about 20 during the observed period. The
evolution of the lines is similar to that of the soft X-rays, indicating that
they arise in the same component. The line ratios are consistent with those
expected from radiative shocks with velocity 310-390 km/s, corresponding to a
shock temperature of (1.6-2.5) x 10^6 K. A fraction of the coronal emission
may, however, originate in higher velocity adiabatic shocks.Comment: 11 pages, 10 figures, accepted for publication in A&
Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography
Free radical scavenging and formation by multi-walled carbon nanotubes in cell free conditions and in human bronchial epithelial cells
Background:
Certain multi-walled carbon nanotubes (MWCNTs) have been shown to elicit asbestos-like toxicological effects. To reduce needs for risk assessment it has been suggested that the physicochemical characteristics or reactivity of nanomaterials could be used to predict their hazard. Fibre-shape and ability to generate reactive oxygen species (ROS) are important indicators of high hazard materials. Asbestos is a known ROS generator, while MWCNTs may either produce or scavenge ROS. However, certain biomolecules, such as albumin – used as dispersants in nanomaterial preparation for toxicological testing in vivo and in vitro - may reduce the surface reactivity of nanomaterials.
Methods:
Here, we investigated the effect of bovine serum albumin (BSA) and cell culture medium with and without BEAS 2B cells on radical formation/scavenging by five MWCNTs, Printex 90 carbon black, crocidolite asbestos, and glass wool, using electron spin resonance (ESR) spectroscopy and linked this to cytotoxic effects measured by trypan blue exclusion assay. In addition, the materials were characterized in the exposure medium (e.g. for hydrodynamic size-distribution and sedimentation rate).
Results:
The test materials induced highly variable cytotoxic effects which could generally be related to the abundance and characteristics of agglomerates/aggregates and to the rate of sedimentation. All carbon nanomaterials were found to scavenge hydroxyl radicals (•OH) in at least one of the solutions tested. The effect of BSA was different among the materials. Two types of long, needle-like MWCNTs (average diameter >74 and 64.2 nm, average length 5.7 and 4.0 µm, respectively) induced, in addition to a scavenging effect, a dose-dependent formation of a unique, yet unidentified radical in both absence and presence of cells, which also coincided with cytotoxicity.
Conclusions:
Culture medium and BSA affects scavenging/production of •OH by MWCNTs, Printex 90 carbon black, asbestos and glass-wool. An unidentified radical is generated by two long, needle-like MWCNTs and these two CNTs were more cytotoxic than the other CNTs tested, suggesting that this radical could be related to the adverse effects of MWCNTs
Serum Lipopolysaccharide Activity Is Associated With the Progression of Kidney Disease in Finnish Patients With Type 1 Diabetes
Modeling the X-ray emission of SN 1993J
We investigate the effects of radiative shocks on the observed X-ray emission
from the Type II supernova SN 1993J. To this end, the X-ray emission is modeled
as a result of the interaction between the supernova ejecta and a dense
circumstellar medium at an age of 8 years. The circumstances under which the
reverse shock is radiative are discussed and the observed X-ray emission is
analyzed using the numerical code described in Nymark et al. (2006). We argue
that the original analysis of the X-ray observations suffered from the lack of
self-consistent models for cooling shocks with high density and velocity,
leading to questionable conclusions about the temperatures and elemental
abundances. We reanalyze the spectra with our numerical model, and discuss the
expected spectra for different explosion models for the progenitors. We find
that the spectra of SN 1993J are compatible with a CNO-enriched composition and
that the X-ray flux is dominated by the reverse shock.Comment: 12 pages, 7 figures, 3 tables. Accepted for publication in A&
Circumstellar interaction in supernovae in dense environments - an observational perspective
In a supernova explosion, the ejecta interacting with the surrounding
circumstellar medium (CSM) give rise to variety of radiation. Since CSM is
created from the mass lost from the progenitor star, it carries footprints of
the late time evolution of the star. This is one of the unique ways to get a
handle on the nature of the progenitor star system. Here, I will focus mainly
on the supernovae (SNe) exploding in dense environments, a.k.a. Type IIn SNe.
Radio and X-ray emission from this class of SNe have revealed important
modifications in their radiation properties, due to the presence of high
density CSM. Forward shock dominance of the X-ray emission, internal free-free
absorption of the radio emission, episodic or non-steady mass loss rate,
asymmetry in the explosion seem to be common properties of this class of SNe.Comment: Fixed minor typos. 31 pages, 9 figures, accepted for publication in
Space Science Reviews. Chapter in International Space Science Institute
(ISSI) Book on "Supernovae" to be published in Space Science Reviews by
Springe
Massive stars as thermonuclear reactors and their explosions following core collapse
Nuclear reactions transform atomic nuclei inside stars. This is the process
of stellar nucleosynthesis. The basic concepts of determining nuclear reaction
rates inside stars are reviewed. How stars manage to burn their fuel so slowly
most of the time are also considered. Stellar thermonuclear reactions involving
protons in hydrostatic burning are discussed first. Then I discuss triple alpha
reactions in the helium burning stage. Carbon and oxygen survive in red giant
stars because of the nuclear structure of oxygen and neon. Further nuclear
burning of carbon, neon, oxygen and silicon in quiescent conditions are
discussed next. In the subsequent core-collapse phase, neutronization due to
electron capture from the top of the Fermi sea in a degenerate core takes
place. The expected signal of neutrinos from a nearby supernova is calculated.
The supernova often explodes inside a dense circumstellar medium, which is
established due to the progenitor star losing its outermost envelope in a
stellar wind or mass transfer in a binary system. The nature of the
circumstellar medium and the ejecta of the supernova and their dynamics are
revealed by observations in the optical, IR, radio, and X-ray bands, and I
discuss some of these observations and their interpretations.Comment: To be published in " Principles and Perspectives in Cosmochemistry"
Lecture Notes on Kodai School on Synthesis of Elements in Stars; ed. by Aruna
Goswami & Eswar Reddy, Springer Verlag, 2009. Contains 21 figure
MR spectroscopy of hepatic fat and adiponectin and leptin levels during testosterone therapy in type 2 diabetes: a randomized, double-blinded, placebo-controlled trial:A randomized, double-blinded, placebo-controlled trial
Background
Men with type 2 diabetes mellitus (T2D) often have lowered testosterone levels and an increased risk of cardiovascular disease (CVD). Ectopic fat increases the risk of CVD, whereas subcutaneous gluteofemoral fat protects against CVD and has a beneficial adipokine-secreting profile.
Hypothesis
Testosterone replacement therapy (TRT) may reduce the content of ectopic fat and improve the adipokine profile in men with T2D.
Design and methods
A randomized, double-blinded, placebo-controlled study in 39 men aged 50–70 years with T2D and bioavailable testosterone levels <7.3 nmol/L. Patients were randomized to TRT (n = 20) or placebo gel (n = 19) for 24 weeks. Thigh subcutaneous fat area (TFA, %fat of total thigh volume), subcutaneous abdominal adipose tissue (SAT, % fat of total abdominal volume) and visceral adipose tissue (VAT, % fat of total abdominal volume) were measured by magnetic resonance (MR) imaging. Hepatic fat content was estimated by single-voxel MR spectroscopy. Adiponectin and leptin levels were measured by in-house immunofluorometric assay. Coefficients (b) represent the placebo-controlled mean effect of intervention.
Results
TFA (b = −3.3 percentage points (pp), P = 0.009), SAT (b = −3.0 pp, P = 0.006), levels of adiponectin (b = −0.4 mg/L, P = 0.045), leptin (b = −4.3 µg/mL, P < 0.001), leptin:adiponectin ratio (b = −0.53, P = 0.001) and HDL cholesterol (b = −0.11 mmol/L, P = 0.009) decreased during TRT compared with placebo. Hepatic fat content and VAT were unchanged.
Conclusions
The effects of TRT on cardiovascular risk markers were ambiguous. We observed potentially harmful changes in cardiovascular risk parameters, markedly reduced subcutaneous fat and unchanged ectopic fat during TRT and a reduction in adiponectin levels. On the other hand, the decrease in leptin and leptin:adiponectin ratio assessments could reflect an amelioration of the cardiovascular risk profile linked to hyperleptinaemia in ageing men with T2D.
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