383 research outputs found
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Studying Lactoferrin N-Glycosylation.
Lactoferrin is a multifunctional glycoprotein found in the milk of most mammals. In addition to its well-known role of binding iron, lactoferrin carries many important biological functions, including the promotion of cell proliferation and differentiation, and as an anti-bacterial, anti-viral, and anti-parasitic protein. These functions differ among lactoferrin homologs in mammals. Although considerable attention has been given to the many functions of lactoferrin, its primary nutritional contribution is presumed to be related to its iron-binding characteristics, whereas the role of glycosylation has been neglected. Given the critical role of glycan binding in many biological processes, the glycan moieties in lactoferrin are likely to contribute significantly to the biological roles of lactoferrin. Despite the high amino acid sequence homology in different lactoferrins (up to 99%), each exhibits a unique glycosylation pattern that may be responsible for heterogeneity of the biological properties of lactoferrins. An important task for the production of biotherapeutics and medical foods containing bioactive glycoproteins is the assessment of the contributions of individual glycans to the observed bioactivities. This review examines how the study of lactoferrin glycosylation patterns can increase our understanding of lactoferrin functionality
In situ measurements of density fluctuations and compressibility in silica glass as a function of temperature and thermal history
In this paper, small-angle X-ray scattering measurements are used to
determine the different compressibility contributions, as well as the
isothermal compressibility, in thermal equilibrium in silica glasses having
different thermal histories. Using two different methods of analysis, in the
supercooled liquid and in the glassy state, we obtain respectively the
temperature and fictive temperature dependences of the isotheraml
compressibility. The values obtained in the glass and supercooled liquid states
are very close to each other. They agree with previous determinations of the
literature. The compressibility in the glass state slightly decreases with
increasing fictive temperature. The relaxational part of the compressibility is
also calculated and compared to previous determinations. We discussed the small
differences between the different determinations
Dynamic sound attenuation at hypersonic frequencies in silica glass
In order to clarify the origin of the dominant processes responsible for the
acoustic attenuation of phonons, which is a much debatted topic, we present
Bril louin scattering experiments in various silica glasses of different OH
impurities content. A large temperature range, from 5 to 1500 K is
investigated, up to the glass transition temperature. Comparison of the
hypersonic wave attenuation in various samples allows to identify two different
processes. The first one induce s a low temperature peak related to
relaxational processes; it is strongly sensitive to the extrinsic defects. The
second, dominant in the hig h temperature range, is weakly dependent on the
impurities and can be ascribed to anharmonic interactions
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Glucagon Secreting Tumors and Glucagonoma Syndrome
Glucagonomas are the functioning neuroendocrine tumors. These arise from pancreatic islet α-cells. These tumors are extremely rare and have an annual incidence of 1 per 20-40 million population 80% of glucagon-expressing tumors are sporadic, and 20% are associated with genetic syndromes such as Multiple Endocrine Neoplasia-type 1. Glucagonoma typically occurs in the distal pancreas, and around 85% are in the body or tail. It tends to be large at the time of diagnosis. Most reported cases of glucagonoma are malignant and about 65-75% patients present with metastatic disease. The liver is usually the first site of metastases, followed by the involvement of peripancreatic lymph nodes. The term Glucagonoma syndrome and glucagonoma are often interchangeably used, but in fact, these are two distinct entities. Glucagonoma syndrome comprises of necrolytic migratory erythema, hyperglucagonemia, diabetes mellitus, anemia, weight loss, glossitis, diarrhea, venous thrombosis and neuropsychiatric disturbances in the presence of a glucagon-producing tumor of the pancreas. Tumors secreting glucagon can occur without the glucagonoma syndrome. The glucagonoma secretion depends on the expression of protein convertase enzyme PC1/3 or PC2 within the tumor itself. As a result of this expression, the clinical manifestations can be variable. The tumor can either present with hyperinsulinemic hypoglycemia in a patient with a previous history of diabetes or with the features of the glucagonoma syndrome. In cases where a tumor is localized surgery is the curative treatment. Reduction of the tumor bulk, removal of the primary by surgery and targeted therapy for the hepatic metastases are the favored approach even when there is the metastasis
Injection Scheme with Deflecting Cavity for Ultimate Storage Ring
We suggest a new on-axis injection scheme that uses two deflecting cavities
to remove the tilt of the stored beam, and to kick the injected beam into the
ring. In this new injection scheme, an injected beam with a certain angle is
overlaid on the stored beam position in transverse phase space through the
second deflecting cavity. (Note that the injected beam has separated phase with
the stored beam in longitudinal phase space). We present theoretical analysis
and numerical simulations of the stored beam and injected beam with the new
injection scheme
Solving the degeneracy of the lepton-flavor mixing angle theta_atm by the T2KK two detector neutrino oscillation experiment
If the atmospheric neutrino oscillation amplitude, sin^2 2theta_atm is not
maximal, there is a two fold ambiguity in the neutrino parameter space: sin^2
theta_atm>0.5 or sin^2 theta_atm<0.5. In this article, we study the impact of
this degeneracy, the so-called octant degeneracy, on the T2KK experiment, which
is a proposed extension of the T2K (Tokai-to-Kaimoka) neutrino oscillation
experiment with an additional water cherenkov detector placed in Korea. We find
that the degeneracy between sin^2 theta_atm= 0.40 and 0.60 can be resolved at
the 3sigma level for sin^2 2theta_rct>0.12 (0.08) for the optimal combination
of a 3.0^circ off-axis beam (OAB) at SK (L=295km) and a 0.5^circ OAB at
L=1000km with a far detector of 100kton volume, after 5 years of exposure with
1.0(5.0) time 10^21 POT/year, if the hierarchy is normal. We also study the
influence of the octant degeneracy on the capability of T2KK experiment to
determine the mass hierarchy and the leptonic CP phase. The capability of
rejecting the wrong mass hierarchy grows with increasing sin^2 theta_atm when
the hierarchy is normal, whereas it is rather insensitive to sin^2 theta_atm
for the inverted hierarchy. We also find that the 1sigma allowed region of the
CP phase is not affected significantly even when the octant degeneracy is not
resolved. All our results are obtained for the 22.5 kton Super-Kamiokande as a
near detector and without an anti-neutrino beam.Comment: 23 pages, 9 figure
Chromophore Ordering by Confinement into Carbon Nanotubes
International audienceWe report an experimental study on the confinement of oligothiophene derivatives into single-walled carbon nanotubes over a large range of diameter (from 0.68 to 1.93 nm). We evidence by means of Raman spectroscopy and transmission electron microscopy that the supramolecular organizations of the confined oligothiophenes depend on the nanocontainer size. The Raman Radial Breathing Mode frequency is shown to be monitored by both the number of confined molecules into a nanotube section and the competition between oligothiophene/oligothiophene and oligothiophene/tube wall interactions. We finally propose simple Raman criteria to characterize oligothiophene supramolecular organization at the nanoscale
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