N-glycans of human amniotic fluid transferrin stimulate progesterone production in human first trimester trophoblast cells in vitro

Aims: During pregnancy, the placenta produces a variety of steroid hormones and proteins. Several of these substances have been shown to exert immunomodulatory effects. Progesterone is thought to mediate some of these effects by regulating uterine responsiveness. The aim of this study was to clarify the effect of amniotic fluid transferrin and its N-glycans on the release of progesterone by first trimester trophoblast cells in vitro. Methods: Cytotrophoblast cells were prepared from human first trimester placentae by trypsin-DNAse dispersion of villous tissue followed by a percoll gradient centrifugation and depletion of CD45 positive cells by magnetic cell sorting. Trophoblasts were incubated with varying concentrations (50-300 mug/ml) of transferrin from human amniotic fluid and serum as well as with N-glycans obtained from amniotic fluid transferrin. Culture supernatants were assayed for progesterone by enzyme-immunometric methods. Results: The release of progesterone increased in amniotic fluid transferrin- and N-glycan-treated trophoblast cell cultures compared to untreated trophoblast cells. There was no stimulating effect of serum transferrin on the progesterone production of trophoblast cells. Conclusions: The results suggest that amnion-transferrin and especially its N-glycans modulate the endocrine function of trophoblasts in culture by up regulating progesterone secretion

Structure, Thermodynamics, and Dynamical Properties of Nucleic Acids, Proteins, and Glass-Forming Liquids

Thesis advisor: Udayan MohantyThe stabilization of particular conformations of protein and nucleic acid structure is believed to play an important role in many important biological functions. In chapter one, the α -helical conformation and structural stability of single and double stapled all- hydrocarbon cross-linked p53 peptides when bound and unbound to MDM2 are investigated. Our study provides a comprehensive rationalization of the relationship between peptide stapling strategy, the secondary structural stability, and the binding affinity of p53-MDM2 complex. In chapter two, we study counterion-mediated collapse of a strongly charged model polyelectrolyte chain by Group-II divalent metal cations using coarse-grained Brownian dynamics simulations. Polyelectrolyte effects govern the association of counterions with the chain. Large ions are less effective in counterion condensation than small ions. However, upon counterion condensation, the reduction of the backbone charge is independent of size of the metal cations. Above a threshold value of Coulomb strength parameter, counterion release entropy drives the formation of counterion-induced compact states. In chapter three, the nature of surface tension in the random first order theory of supercooled liquid is analyzed within the framework of Landau-Lifshitz fluctuation theory. We show that the surface tension of a droplet satisfies the differential equation 4πr2(dσ)+ 8πrσ(r)− Br1/2 = 0 , where B/ T = 12πkBcv , T is temperature, kB is dr Boltzmann constant, and cv is heat capacity. A consequence is that the slope of the relaxation time at the glass transition temperature, i.e., the fragility index, is expressed as the square of the ratio of heat capacity and configurational entropy of the supercooled liquid. When backbone extended nucleosides are incorporated into a double helix, a unique helical structure is formed. In chapter four, we find that the predicted stability of modified backbone DNA strands in aqueous solution is in good agreement with experimental melting temperature data. The incorporation of extended backbone nucleosides into a duplex results in elongation of the end-to-end chain distance due to the distortion of the B-DNA conformation at the mutated base-pair insertion. We also find that the modified backbone helical twist is approximately 40 degrees, larger than B-DNA helical twist and closer to the twist angle predicted for D-form DNA. The folding of RNA tertiary structure has been described as an equilibrium between partially folded I (intermediate) states, and the fully folded native conformation, or N state. RNA is highly sensitive to the ionic environment due to its negative charge, and tertiary structures tend to be strongly stabilized by Mg2+. There is a need for models capable of describing the ion atmosphere surrounding RNA with quantitative accuracy. In chapter 5, we present a generalized Manning condensation model of RNA electrostatics for studying the Mg2+-induced RNA folding of the 58mer ribosomal fragment.Thesis (PhD) — Boston College, 2016.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Chemistry

Solubility of iron in the Southern Ocean

Iron solubility (cFeS) ranged from 0.4 to 1.5 nmol L−1, decreasing from south to north in three different Southern Ocean zones (the Coastal Zone, the Antarctic Zone, and the Polar Frontal Zone plus the Subantarctic Zone). This decrease was at times correlated with an increase in temperature. Organic Fe solubility (cFeS,org), which was obtained by subtracting from total measured Fe solubility the solubility of inorganic species of iron (Fe) at the measurement temperature (20°C), ranged from 0.3 to 1.3 nmol L−1, representing an average of 32 ± 14% of the concentration of ligands in the dissolved size fraction as determined via competitive ligand exchange–absorptive cathodic stripping voltammetry (barring a handful of extremely high values from a transect run to the east of Prydz Bay). Values of cFeS were mainly lower than the predicted value for inorganic Fe solubility at the in situ temperature. Total in situ Fe solubility (cFeS,adj) was therefore estimated by adjusting for inorganic Fe solubility at in situ temperatures (between −2°C and +18°C). Because in situ temperatures in the Antarctic Circumpolar Current were mostly lower than +3°C, such cFeS,adj values, ranging from 0.5 to 1.8 nmol L−1, were roughly twice as large as cFeS,org. The adjustment relies heavily on model calculations of inorganic Fe solubility but, if correct, indicates that the bulk of the solubility of Fe in the cold waters of the Southern Ocean is tied to the solubility of inorganic Fe rather than to Fe ligands in the soluble size fraction

Vivaspin ultrafiltration: A new approach for high resolution measurements of colloidal and soluble iron species

Vivaspin6® ultrafiltration units with molecular weight “cut-off” membranes of 5, 10, 30, 50, and 100 kDa were used together to examine the size distribution of newly formed iron (Fe) colloids in natural seawater samples and in the presence of several different Fe chelators with varying Fe binding strength. Artificial Fe chelators, such as TAC, and 2 kDG, when added at equimolar levels to Fe, supported the formation of a continuum of Fe-ligand colloids between 5 and 100 kDa. More than 90% of the added 55Fe in these solutions occurred in Fe aggregates/particles larger than 100 kDa. The strong siderophore DFO held the majority of the added 55Fe in the “truly” soluble fraction ≤ 5 kDa, whereas 90% of 55Fe added to UV-irradiated seawater was converted into Fe colloids with a size between 50 to 100 kDa (5–6 nm). Membranes with ≥ 10 kDa showed similar “cut-off” properties on natural seawater samplescollected in the water column off the Peruvian coast. Fe solubility determined with these membranes was approximately six times greater than Fe solubility determined with the 5 kDa membrane and the 0.02 μm syringe filters. This suggests that a seamless size continuum of organic chelators (≤5 kDa–10 kDa) is present in these seawaters and that estimates of ligand production based on 0.02 μm Anotop solubility experiments underestimates the abundance of soluble/colloidal ligands. Regarding these results, we recommend the use of Vivaspin 5 kDa membranes to separate the “truly” soluble from the colloidal Fe fraction

Acute gallbladder torsion - a continued pre-operative diagnostic dilemma

Acute gallbladder volvulus continues to remain a relatively uncommon process, manifesting itself usually during exploration for an acute surgical abdomen with a presumptive diagnosis of acute cholecystitis. The pathophysiology is that of mechanical organo-axial torsion along the gallbladder's longitudinal axis involving the cystic duct and cystic artery, and with a pre-requisite of local mesenteric redundancy. The demographic tendency is septua- and octo-genarians of the female sex, and its overall incidence is increasing, this being attributed to increasing life expectancy. We discuss two cases of elderly, fragile women presenting to the emergency department complaining of sudden onset right upper quadrant abdominal pain. Their subsequent evaluation suggested acute cholecystitis. Ultimately both were taken to the operating room where the correct diagnosis of gallbladder torsion was made. Pre-operative diagnosis continues to be a major challenge with only 4 cases reported in the literature diagnosed with pre-operative imaging; the remainder were found intra-operatively. Consequently, a delay in diagnosis can have devastating patient outcomes. Herein we propose a necessary high index of suspicion for gallbladder volvulus in the outlined patient demographic with symptoms and signs mimicking acute cholecystitis

Impacts of dust deposition on dissolved trace metal concentrations (Mn, Al and Fe) during a mesocosm experiment

The deposition of atmospheric dust is the primary process supplying trace elements abundant in crustal rocks (e.g. Al, Mn and Fe) to the surface ocean. Upon deposition, the residence time in surface waters for each of these elements differs according to their chemical speciation and biological utilization. Presently, however, the chemical and physical processes occurring after atmospheric deposition are poorly constrained, principally because of the difficulty in following natural dust events in situ. In the present work we examined the temporal changes in the biogeochemistry of crustal metals (in particular Al, Mn and Fe) after an artificial dust deposition event. The experiment was contained inside trace metal clean mesocosms (0–12.5 m depths) deployed in the surface waters of the northwestern Mediterranean, close to the coast of Corsica within the frame of the DUNE project (a DUst experiment in a low Nutrient, low chlorophyll Ecosystem). Two consecutive artificial dust deposition events, each mimicking a wet deposition of 10 g m−2 of dust, were performed during the course of this DUNE-2 experiment. The changes in dissolved manganese (Mn), iron (Fe) and aluminum (Al) concentrations were followed immediately after the seeding with dust and over the following week. The Mn, Fe and Al inventories and loss or dissolution rates were determined. The evolution of the inventories after the two consecutive additions of dust showed distinct behaviors for dissolved Mn, Al and Fe. Even though the mixing conditions differed from one seeding to the other, Mn and Al showed clear increases directly after both seedings due to dissolution processes. Three days after the dust additions, Al concentrations decreased as a consequence of scavenging on sinking particles. Al appeared to be highly affected by the concentrations of biogenic particles, with an order of magnitude difference in its loss rates related to the increase of biomass after the addition of dust. In the case of dissolved Fe, it appears that the first dust addition resulted in a decrease as it was scavenged by sinking dust particles, whereas the second seeding induced dissolution of Fe from the dust particles due to the excess Fe binding ligand concentrations present at that time. This difference, which might be related to a change in Fe binding ligand concentration in the mesocosms, highlights the complex processes that control the solubility of Fe. Based on the inventories at the mesocosm scale, the estimations of the fractional solubility of metals from dust particles in seawater were 1.44 ± 0.19% and 0.91 ± 0.83% for Al and 41 ± 9% and 27 ± 19% for Mn for the first and the second dust addition. These values are in good agreement with laboratory-based estimates. For Fe no fractional solubility was obtained after the first seeding, but 0.12 ± 0.03% was estimated after the second seeding. Overall, the trace metal dataset presented here makes a significant contribution to enhancing our knowledge on the processes influencing trace metal release from Saharan dust and the subsequent processes of bio-uptake and scavenging in a low nutrient, low chlorophyll are

Winter 1972

Factors Affecting the Adaptation and Competitiveness of Poa Annua L. (3) Environmental Factors Influencing Turfgrass Diseases (6) Turfgrass Seeds by the Pound (10) Too Heavy or Too Light (11) Plant Resistance to Insects (13) Control of the Hairy Chinch Bug in Turfgrass in the Northeast with Dursban Insecticide (22) University of Massachusetts Turfgrass Research Fund (24