373 research outputs found
Renal cell carcinoma metastatic to the duodenum: Treatment by classic pancreaticoduodenectomy and review of the literature
Renal cell cancer (RCC) most commonly metastasizes to the lungs, bones, liver, renal fossa, and brain, although metastases can occur elsewhere. RCC metastatic to the duodenum is especially rare, with only a small number of cases reported in the literature. Herein, we describe a case of an 86-year-old woman with a history of RCC treated by radical nephrectomy 13 years previously. The patient presented with duodenal obstruction and anemia from a solitary duodenal mass invading into the pancreas and was treated via classic pancreaticoduodenectomy. Preoperative imaging and intra-operative assessment showed no evidence of other disease. Pathology confirmed metastatic RCC without lymph node involvement. Our case report and review of the English language literature underscore the rarity of this entity and support aggressive surgical treatment in such patients
Design of photoactivatable metallodrugs : selective and rapid light-induced ligand dissociation from half-sandwich [Ru([9]aneS3)(N–N′)(py)]2+ complexes
The synthesis of the inert Ru(II) half-sandwich coordination compounds, [Ru([9]aneS3)(bpy)(py)][PF6]2 (1, [9]aneS3 = 1,4,7-trithiacyclononane, bpy = 2,2′-bipyridine, py = pyridine), [Ru([9]aneS3)(en)(py)][PF6]2 (2, en = 1,2-diaminoethane), and [Ru([9]aneN3)(en)(dmso-S)][PF6]2 (3, [9]aneN3 = 1,4,7-triazacyclononane), is reported along with the X-ray crystal structure of 1. We investigated whether these complexes have photochemical properties which might make them suitable for use as pro-drugs in photochemotherapy. Complexes 1 and 2 underwent rapid (minutes) aquation with dissociation of the pyridine ligand in aqueous solution when irradiated with blue light (λ = 420 or 467 nm). The photodecomposition of 3 was much slower. All complexes readily formed adducts with 9-ethylguanine (9-EtG) when this model nucleobase was present in the photolysis solution. Similarly, complex 1 formed adducts with the tripeptide glutathione (GSH), but only when photoactivated. HPLC and MS studies of 1 showed that irradiation promoted rapid formation of 1:1 (major) and 1:2 (minor) adducts of the oligonucleotide d(ATACATGCTACATA) with the fragment {Ru([9]aneS3)(bpy)}2+. Density functional theory (DFT) calculations and time-dependent DFT reproduced the major features of the absorption spectra and suggested that the lowest-lying triplet state with 3MLCT character, which is readily accessible via intersystem crossing, might be responsible for the observed dissociative behavior of the excited states. These complexes are promising for further study as potential photochemotherapeutic agents
A galactic-scale origin for stellar clustering
We recently presented a model for the cluster formation efficiency (CFE),
i.e. the fraction of star formation occurring in bound stellar clusters. It
utilizes the idea that the formation of stars and stellar clusters occurs
across a continuous spectrum of ISM densities. Bound stellar clusters naturally
arise from the high-density end of this density spectrum. Due to short
free-fall times, these high-density regions can achieve high star formation
efficiencies (SFEs) and can be unaffected by gas expulsion. Lower-density
regions remain gas-rich and substructured, and are unbound upon gas expulsion.
The model enables the CFE to be calculated using galactic-scale observables. I
present a brief summary of the model physics, assumptions and caveats, and show
that it agrees well with observations. Fortran and IDL routines for calculating
the CFE are publicly available at http://www.mpa-garching.mpg.de/cfe.Comment: 4 pages, 1 figure; to appear in The Labyrinth of Star Formation,
(eds.) D. Stamatellos, S. Goodwin, and D. Ward-Thompson, Springer, in pres
Electron affinities of the first- and second- row atoms: benchmark ab initio and density functional calculations
A benchmark ab initio and density functional (DFT) study has been carried out
on the electron affinities of the first- and second-row atoms. The ab initio
study involves basis sets of and quality, extrapolations to
the 1-particle basis set limit, and a combination of the CCSD(T), CCSDT, and
full CI electron correlation methods. Scalar relativistic and spin-orbit
coupling effects were taken into account. On average, the best ab initio
results agree to better than 0.001 eV with the most recent experimental
results. Correcting for imperfections in the CCSD(T) method improves the mean
absolute error by an order of magnitude, while for accurate results on the
second-row atoms inclusion of relativistic corrections is essential. The latter
are significantly overestimated at the SCF level; for accurate spin-orbit
splitting constants of second-row atoms inclusion of (2s,2p) correlation is
essential. In the DFT calculations it is found that results for the 1st-row
atoms are very sensitive to the exchange functional, while those for second-row
atoms are rather more sensitive to the correlation functional. While the LYP
correlation functional works best for first-row atoms, its PW91 counterpart
appears to be preferable for second-row atoms. Among ``pure DFT'' (nonhybrid)
functionals, G96PW91 (Gill 1996 exchange combined with Perdew-Wang 1991
correlation) puts in the best overall performance. The best results overall are
obtained with the 1-parameter hybrid modified Perdew-Wang (mPW1) exchange
functionals of Adamo and Barone [J. Chem. Phys. {\bf 108}, 664 (1998)], with
mPW1LYP yielding the best results for first-row, and mPW1PW91 for second-row
atoms. Indications exist that a hybrid of the type mPW1LYP +
mPW1PW91 yields better results than either of the constituent functionals.Comment: Phys. Rev. A, in press (revised version, review of issues concerning
DFT and electron affinities added
On single and double soft behaviors in NLSM
In this paper, we study the single and double soft behaviors of tree level
off-shell currents and on-shell amplitudes in nonlinear sigma model(NLSM). We
first propose and prove the leading soft behavior of the tree level currents
with a single soft particle. In the on-shell limit, this single soft emission
becomes the Adler's zero. Then we establish the leading and sub-leading soft
behaviors of tree level currents with two adjacent soft particles. With a
careful analysis of the on-shell limit, we obtain the double soft behaviors of
on-shell amplitudes where the two soft particles are adjacent to each other. By
applying Kleiss-Kuijf (KK) relation, we further obtain the leading and
sub-leading behaviors of amplitudes with two nonadjacent soft particles.Comment: 41 pages, 6 tables, 9 figures, minor revised, more content about
nonadjacent double soft limit, update the reference
Star forming dwarf galaxies
Star forming dwarf galaxies (SFDGs) have a high gas content and low
metallicities, reminiscent of the basic entities in hierarchical galaxy
formation scenarios. In the young universe they probably also played a major
role in the cosmic reionization. Their abundant presence in the local volume
and their youthful character make them ideal objects for detailed studies of
the initial stellar mass function (IMF), fundamental star formation processes
and its feedback to the interstellar medium. Occasionally we witness SFDGs
involved in extreme starbursts, giving rise to strongly elevated production of
super star clusters and global superwinds, mechanisms yet to be explored in
more detail. SFDGs is the initial state of all dwarf galaxies and the relation
to the environment provides us with a key to how different types of dwarf
galaxies are emerging. In this review we will put the emphasis on the exotic
starburst phase, as it seems less important for present day galaxy evolution
but perhaps fundamental in the initial phase of galaxy formation.Comment: To appear in JENAM Symposium "Dwarf Galaxies: Keys to Galaxy
Formation and Evolution", P. Papaderos, G. Hensler, S. Recchi (eds.). Lisbon,
September 2010, Springer Verlag, in pres
Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.
Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition
No Evidence for a Trade-Off between Reproductive Investment and Immunity in a Rodent
Life history theory assumes there are trade-offs between competing functions such as reproduction and immunity. Although well studied in birds, studies of the trade-offs between reproduction and immunity in small mammals are scarce. Here we examined whether reduced immunity is a consequence of reproductive effort in lactating Brandt's voles (Lasiopodomys brandtii). Specifically, we tested the effects of lactation on immune function (Experiment I). The results showed that food intake and resting metabolic rate (RMR) were higher in lactating voles (6≤ litter size ≤8) than that in non-reproductive voles. Contrary to our expectation, lactating voles also had higher levels of serum total Immunoglobulin G (IgG) and anti-keyhole limpet hemocyanin (KLH) IgG and no change in phytohemagglutinin (PHA) response and anti-KLH Immunoglobulin M (IgM) compared with non-reproductive voles, suggesting improved rather than reduced immune function. To further test the effect of differences in reproductive investment on immunity, we compared the responses between natural large (n≥8) and small litter size (n≤6) (Experiment II) and manipulated large (11–13) and small litter size (2–3) (Experiment III). During peak lactation, acquired immunity (PHA response, anti-KLH IgG and anti-KLH IgM) was not significantly different between voles raising large or small litters in both experiments, despite the measured difference in reproductive investment (greater litter size, litter mass, RMR and food intake in the voles raising larger litters). Total IgG was higher in voles with natural large litter size than those with natural small litter size, but decreased in the enlarged litter size group compared with control and reduced group. Our results showed that immune function is not suppressed to compensate the high energy demands during lactation in Brandt's voles and contrasting the situation in birds, is unlikely to be an important aspect mediating the trade-off between reproduction and survival
The Fanconi Anemia Core Complex Is Dispensable during Somatic Hypermutation and Class Switch Recombination
To generate high affinity antibodies during an immune response, B cells undergo somatic hypermutation (SHM) of their immunoglobulin genes. Error-prone translesion synthesis (TLS) DNA polymerases have been reported to be responsible for all mutations at template A/T and at least a fraction of G/C transversions. In contrast to A/T mutations which depend on PCNA ubiquitination, it remains unclear how G/C transversions are regulated during SHM. Several lines of evidence indicate a mechanistic link between the Fanconi Anemia (FA) pathway and TLS. To investigate the contribution of the FA pathway in SHM we analyzed FancG-deficient B cells. B cells deficient for FancG, an essential member of the FA core complex, were hypersensitive to treatment with cross-linking agents. However, the frequencies and nucleotide exchange spectra of SHM remained comparable between wild-type and FancG-deficient B cells. These data indicate that the FA pathway is not involved in regulating the outcome of SHM in mammals. In addition, the FA pathway appears dispensable for class switch recombination
A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor
Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses
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