1,020 research outputs found
Intact glycopeptide analysis of recombinant protein from CHO cells
The quality of recombinant glycoproteins including antibodies and other biologics is dictated by their glycan profiles. What is missing is how to analyze these glycans rapidly for process improvement and control applications. Conventional glycan analysis involves the release of glycans, which rarely captures the glycan site-specific information. Intact glycopeptide analysis in which glycans are retained on the peptide provides insights into the glycan structure and the glycosylation site information simultaneously. This information can reveal additional details about site occupancy and cellular glycosylation of proteins. Avoiding glycan release and some modifications and labeling steps in our intact glycopeptide analysis can result in a shorter sample preparation time than conventional glycan analysis methods. Compared to peptide mapping using LC-MS to decipher protein amino acid sequence in proteomics, this analysis focuses on glycopeptide profiling following protease-digestion. With the aid of LC-MS/MS, we are able to obtain targeted glycoprotein sequence information, glycan profiles and glycan distribution at specific sites. Here we present the application of glycopeptide analysis for model AMBIC and other proteins from CHO-GS and CHO-K1 cells. The site-specific glycosylation patterns of our model proteins EPO-Fc and EPO are characterized. Further, we examine the impact of media formulation and additives on the glycan profiles for these proteins.
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Charged particles in a rotating magnetic field
We study the valence electron of an alkaline atom or a general charged
particle with arbitrary spin and with magnetic moment moving in a rotating
magnetic field. By using a time-dependent unitary transformation, the
Schr\"odinger equation with the time-dependent Hamiltonian can be reduced to a
Schr\"odinger-like equation with a time-independent effective Hamiltonian.
Eigenstates of the effective Hamiltonian correspond to cyclic solutions of the
original Schr\"odinger equation. The nonadiabatic geometric phase of a cyclic
solution can be expressed in terms of the expectation value of the component of
the total angular momentum along the rotating axis, regardless of whether the
solution is explicitly available. For the alkaline atomic electron and a strong
magnetic field, the eigenvalue problem of the effective Hamiltonian is
completely solved, and the geometric phase turns out to be a linear combination
of two solid angles. For a weak magnetic field, the same problem is solved
partly. For a general charged particle, the problem is solved approximately in
a slowly rotating magnetic field, and the geometric phases are also calculated.Comment: REVTeX, 13 pages, no figure. There are two minor errors in the
published version due to incorrect editing by the publisher. The "spin-1" in
Sec. I and the "spin 1" in Sec. II below Eq. (2c) should both be changed to
"spin" or "spin angular momentum". The preferred E-mail for correspondence is
[email protected] or [email protected]
Keck/Palomar Cosmic Web Imagers (KCWI/PCWI) Reveal an Enormous Ly Nebula in an Extremely Overdense QSO Pair Field at
Enormous Ly nebulae (ELANe) represent the extrema of Ly
nebulosities. They have detected extents of kpc in Ly and
Ly luminosities erg s. The ELAN population is an
ideal laboratory to study the interactions between galaxies and the
intergalactic/circumgalactic medium (IGM/CGM) given their brightness and sizes.
The current sample size of ELANe is still very small, and the few
ELANe discovered to date are all associated with local overdensities of active
galactic nuclei (AGNs). Inspired by these results, we have initiated a survey
of ELANe associated with QSO pairs using the Palomar and Keck Cosmic Web
Imagers (PCWI/KCWI). In this letter, we present our first result: the discovery
of ELAN0101+0201 associated with a QSO pair at . Our PCWI discovery
data shows that, above a 2- surface brightness of
\sbunit, the end-to-end size of ELAN0101+0201 is kpc. We have
conducted follow-up observations using KCWI, resolving multiple Ly
emitting sources within the rectangular field-of-view of
projected kpc, and obtaining their emission line profiles at high
signal-to-noise ratios. Combining both KCWI and PCWI, our observations confirm
that ELAN0101+0201 resides in an extremely overdense environment. Our
observations further support that a large amount of cool (K) gas
could exist in massive halos (MM) at .
Future observations on a larger sample of similar systems will provide
statistics of how cool gas is distributed in massive overdensities at
high-redshift and strongly constrain the evolution of the intracluster medium
(ICM).Comment: Submitted to Astrophysical Journal Letter, 9 pages, 4 figures,
Comments Welcom
Time evolution, cyclic solutions and geometric phases for general spin in an arbitrarily varying magnetic field
A neutral particle with general spin and magnetic moment moving in an
arbitrarily varying magnetic field is studied. The time evolution operator for
the Schr\"odinger equation can be obtained if one can find a unit vector that
satisfies the equation obeyed by the mean of the spin operator. There exist at
least cyclic solutions in any time interval. Some particular time
interval may exist in which all solutions are cyclic. The nonadiabatic
geometric phase for cyclic solutions generally contains extra terms in addition
to the familiar one that is proportional to the solid angle subtended by the
closed trace of the spin vector.Comment: revtex4, 8 pages, no figur
First evidence of middle atmospheric HO_2 response to 27 day solar cycles from satellite observations
HO_2 and OH, also known as HO_x, play an important role in controlling middle atmospheric O_3. Due to their photochemical production and short chemical lifetimes, HO_x are expected to respond rapidly to solar irradiance changes, resulting in O_3 variability. While OH solar cycle signals have been investigated, HO_2 studies have been limited by the lack of reliable observations. Here we present the first evidence of HO_2 variability during solar 27 day cycles by investigating the recently developed HO_2 data from the Aura Microwave Limb Sounder (MLS). We focus on 2012–2015, when solar variability is strong near the peak of Solar Cycle 24. The features of HO_2 variability, with the strongest signals at 0.01–0.068 hPa, correlate well with those of solar Lyman α. When continuous MLS OH observations are not available, the new HO_2 data could be a promising alternative for investigating HO_x variability and the corresponding impacts on O_3 and the climate
Therapeutic Strategies Targeting Cancer Stem Cells and Their Microenvironment
Cancer stem cells (CSCs) have been demonstrated in a variety of tumors and are thought to act as a clonogenic core for the genesis of new tumor growth. This small subpopulation of cancer cells has been proposed to help drive tumorigenesis, metastasis, recurrence and conventional therapy resistance. CSCs show self-renewal and flexible clonogenic properties and help define specific tumor microenvironments (TME). The interaction between CSCs and TME is thought to function as a dynamic support system that fosters the generation and maintenance of CSCs. Investigation of the interaction between CSCs and the TME is shedding light on the biologic mechanisms underlying the process of tumor malignancy, metastasis, and therapy resistance. We summarize recent advances in CSC biology and their environment, and discuss the challenges and future strategies for targeting this biology as a new therapeutic approach
The endogenous cell-fate factor dachshund restrains prostate epithelial cell migration via repression of cytokine secretion via a cxcl signaling module.
Prostate cancer is the second leading form of cancer-related death in men. In a subset of prostate cancer patients, increased chemokine signaling IL8 and IL6 correlates with castrate-resistant prostate cancer (CRPC). IL8 and IL6 are produced by prostate epithelial cells and promote prostate cancer cell invasion; however, the mechanisms restraining prostate epithelial cell cytokine secretion are poorly understood. Herein, the cell-fate determinant factor DACH1 inhibited CRPC tumor growth in mice. Using Dach1(fl/fl)/Probasin-Cre bitransgenic mice, we show IL8 and IL6 secretion was altered by approximately 1,000-fold by endogenous Dach1. Endogenous Dach1 is shown to serve as a key endogenous restraint to prostate epithelial cell growth and restrains migration via CXCL signaling. DACH1 inhibited expression, transcription, and secretion of the CXCL genes (IL8 and IL6) by binding to their promoter regulatory regions in chromatin. DACH1 is thus a newly defined determinant of benign and malignant prostate epithelium cellular growth, migration, and cytokine abundance in vivo
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