Measurements Of Total Surface Area Research Articles

Synergistic Prostate Cancer Targeted Radiosensitization by Gold Nanoparticles and Histone Deacetylase Inhibitor Romidepsin

<h3>Purpose/Objective(s)</h3> Histone deacetylase inhibitors (HDACi), such as Romidepsin (FK228) have been confirmed as effective anticancer agents for liquid cancers, but systemic toxicity hinders their application in solid tumors. Gold nanoparticles (GNPs) with tumor specific ligands can be actively accumulated in the targeted tumor, elevating HDACi delivery efficiency. Moreover, GNPs demonstrate their exceptional competence in improving radiosensitization through locally enhanced radiation scatter in the tumor. In this study, we examined the synergistic consequence of prostate cancer treatment with FK228 conjugated GNPs and investigate the molecular mechanism underlying radiosensitization. <h3>Materials/Methods</h3> GNPs were thiolated with N-succinimidyl 3-(2-pyridyldithio)-propionate (SPDP). FK228 and αPSMA antibody were reduced with tris(2-carboxyethyl)-phosphine and mixed with GNPs at a 10:1 ratio, respectively. Dynamic light scattering (DLS) and enzyme linked immunosorbent assay (ELISA) confirmed conjugation, and targeting efficiency was assessed with immunofluorescence (IF) staining of GNPs. PSMA-targeted GNPs (pGNP), and pGNP+FK228 (pfGNP) were treated to LNCaP cells at varying concentrations and monitored on a real time cell analysis (RTCA) system. Western blot (WB) was performed on HDACi pathways. Finally, 2Gy at 160kVp was delivered to cells. 1hr post irradiation, cells were fixed and stained with γH2AX antibodies. Foci count and size were quantified. <h3>Results</h3> DLS showed shift in GNP hydrodynamic size from 49nm to 52nm when conjugated to αPSMA antibody or antibody and FK228. Zeta potential changed from -8mv to -14mV and -20mV in pGNP and pfGNP, respectively. ELISA revealed successful conjugation of αPSMA antibodies with ∼4 antibodies per GNP. IF demonstrated that pfGNP have three-fold higher accumulation on LNCaP cells compared to untargeted GNPs. Based on RTCA, pGNP showed cell killing starting at 1mg/mL at 24hrs, while pfGNP started cell killing at 10µg/mL, but the initiation ranged from 72hrs to 24hrs in a dose dependent manner. At non-toxic concentrations of FK228 and pfGNP, WB revealed both treatments induced a lower expression of androgen receptor and increased expression of ATF3, while pGNP did not. γH2AX assay revealed an increased formation of foci with the treatment of pGNP (158%), FK228 (125%), and pfGNP (170%). There was no statistically significant increase in the foci count between pGNP and pfGNP. However, measurements of total surface area per foci revealed a statistically significant increase in foci size from FK228 and pfGNP compared to pGNP. <h3>Conclusion</h3> FK228 and PSMA-antibodies were successfully conjugated to GNPs using SPDP chemistry. Furthermore, pfGNP demonstrated increased prostate cancer affinity and induced similar cellular signaling as free FK228. Finally, conjugation of FK228 to GNPs synergistically improved prostate cancer radiosensitization through greater induction of double stranded DNA breaks in vitro.

Examining the association between adiposity and biochemical recurrence after radical prostatectomy.

Herein, we examined the association between adiposity, as measured by computed tomography (CT), and biochemical recurrence (BCR) after radical prostatectomy (RP). Using axial CT images, preoperative fat mass index (FMI) was calculated for 698 men who underwent RP from 2007-2010 by using measurements of total surface area of adipose tissue at the L3 level. Obesity was classified according to National Health and Nutrition Examination Survey (NHANES) standards for obesity (FMI >9 kg/m2). The associations between obesity and the distribution of adiposity (visceral vs. subcutaneous) with BCR were examined using the Kaplan-Meier method and Cox proportional hazards regression analyses. Obese men were older than non-obese men (63.0 vs. 60.7 years; p<0.001), but were similar with regards to all other clinical and pathological characteristics. With a median followup of six years, 152 patients were diagnosed with BCR. Five-year BCR-free survival was similar between obese and non-obese patients (80.6% vs. 82.1%; p=0.27). Furthermore, in multivariable analyses, obesity was not independently associated with the risk of BCR (hazard ratio [HR] 1.02; 95% confidence interval [CI] 0.73-1.43). Similar results were obtained when analyzing FMI as a continuous variable (HR 1.02; 95% CI 0.94-1.09 for each 1 kg/m2 increase in FMI). Additionally, neither visceral adiposity, subcutaneous adiposity, or visceral-to-subcutaneous adiposity ratio were associated with BCR (all p>0.05) in multivariable analyses. Neither total abdominal adiposity nor the distribution of adiposity were independently associated with BCR after RP in this study. As such, the presence of obesity may not be a marker of increased oncological risk after RP.

Catalyzed Synthesis of Zinc Clays by Prebiotic Central Metabolites

How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence on succinate for the synthesis of sauconite identifying new mechanisms of clay formation in surface environments of rocky planets. The work demonstrates that seeding induces nucleation at low temperatures accelerating the crystallization process. Cryogenic and conventional transmission electron microscopies, X-ray diffraction, diffuse reflectance Fourier transformed infrared spectroscopy, and measurements of total surface area are used to build a three-dimensional representation of the clay. These results suggest the coevolution of clay minerals and early metabolites in our planet could have been facilitated by sunlight photochemistry, which played a significant role in the complex interplay between rocks and life over geological time.

Estimation of Solute Concentrations in Micro-pore and Macro-pore Solutions of Compacted Bentonite–Sand Mixtures

Densely compacted bentonite has been identified as a potential buffer in deep geological repositories as the expansive clay satisfies the hydro-mechanical and physico-chemical functions of the buffer material. A key feature in understanding the hydro-mechanical behaviour of compacted bentonite upon exposure to chemical concentration gradients is to estimate the solute concentrations in micro-pore and macro-pore solutions. This study describes a method based on measurements of total surface area, external surface area, c-axis (2d) spacings and volumetric calculations to determine the solute concentrations in micro-pore and macro-pore solutions of compacted bentonite-enhanced sand (BES) specimens. Results of the study with Barmer bentonite-based BES specimens illustrate that cation concentrations in micro-pore and macro-pore solutions are sensitive to variations in dry density. Further, the exchangeable cation concentrations in the micro-pore solution exceed the soluble salt-cation concentrations in the macro-pore solution of Barmer bentonite.

Measurement of surface area, gel weight and saliva weight in a gelatin-based gel over the course of mastication

The aim was to devise a method for the measurement of total surface area and weight, as well as saliva weight, for a gelatin-based confectionery gel over the course of human mastication for input into separate modelling of flavour release. The method is based on an alcohol rinse to remove saliva, followed by immersion in amaranth dye to give a thin surface dye layer coating the gel fragments. Total surface area is then found by measurement of quantity of absorbed dye. The resulting time profiles for the six panellists showed that surface area reached a maximum of 3000 mm2 with the 4.28 g gel weight being consumed over 41 to 64 sec with differing numbers of swallows (4-6) and chews (52-103). Calculated total relative saliva weights, 498-993 g kg−1, and flow rates, 2.8-5.6 g min−1, were towards the upper range of those reported in the literature.

The effects of cofiring natural gas and coal on sulfur retention in ash

Under certain conditions, cofiring natural gas with coal has been shown to reduce SO x emissions beyond the reduction expected from simple replacement of sulfur-bearing coal. This enhanced reduction of sulfur emissions, known as sulfur leveraging, is believed to result from increased sulfur capture in coal ash. In this research, experiments with three coals, using size ranges from 90 to 106 μm and 125 to 150 μm, and furnace temperatures of 1300 and 1550 K, demonstrate the extent of sulfur leveraging through increased sulfur retention in ash when cofiring coal and natural gas. Leveraging is shown to be affected by residence time (through particle size) and furnace temperature, while original sulfur form (pyritic or organic) and coal sorbent capacity are shown to have little effect. Results from sorbent activation studies, SEM images, and N 2 adsorption measurement of total surface area indicate that the effects of a natural gas flame on ash sorbent reactivity and ash surface area are minimal. Results also indicate that the primary mechanism for sulfur leveraging is the gas phase conversion of SO 2 to more reactive SO 3, as caused by the natural gas flame. Results from numerical modeling of the furnace environment, particle combustion, and the evolution of sulfur to SO 3 support the experimental findings.

Application of spin-spin relaxation to measurement of surface area and pore size distributions in a hydrating cement paste

Nuclear magnetic resonance (NMR) relaxation analysis has been applied to interpret the evolution of microstructure in a cement paste during hydration. Measurements of transverse magnetic relaxation were made in fully and partially filled white cement pastes for hydration times between 1 h and 6 mo. It was found that only the evaporable water molecules contributed to the echo amplitude in the NMR measurement, while both the evaporable and the hydrated water contribute to the amplitude of the free induction decay. The spin-spin relaxation rate was found to increase markedly during hydration and can be directly related to the total surface area of the CSH gel accessible to evaporable water. The amount of water consumed during the hydration process was determined independently from the amplitude of the NMR echo signal extrapolated to the beginning of the pulse sequence. A numerical inversion of the full spin-spin relaxation profile, determined with a CPMG pulse sequence, was interpreted as a pore volume distribution function. The measurements of total surface area, amount of water consumed, and pore distributions were performed in situ nondestructively, throughout the hydration period for a single sample of cement paste.

Chemistry of illite-smectite inferred from TEM measurements of fundamental particles

AbstractMixed-layer illite-smectites (I-S) have a stable charge on the illite interlayer equal to 0·89/O10(OH)2, as shown by electron microscope measurements of mean fundamental particle thickness, using both Pt-shadowing and high-resolution techniques. This has been verified by independent measurements of total surface area and CEC. Typically, the smectite interlayer charge is close to 0·4/O10(OH)2 but clays evolving in K-deficient environments may exhibit higher values. In the course of illitization, the silicate layer composition becomes more restricted than the smectite composition, AlIV and AlVI increasing while Fe and Mg decrease. These substitutions lead to the composition of non-expandable illite differing distinctly from that of muscovite and phengite, close to FIX0·89Al1·85Fe0·05Mg0·10Si3·20Al0·80. HRTEM data show that XRD systematically underestimates %S layers in I-S due to the small size of coherent scattering domains. An experimental curve is proposed for correcting XRD data. The above results were obtained for I-S formed from volcanic materials in different diagenetic and hydrothermal environments. The illite interlayer charge value close to 0·9 reconciles well the available data on I-S produced by wetting and drying of K-smectites.

Limitations of EGME retention to estimate the surface area of soils

The suitability of two procedures for the measurement of total surface area, based on 'the retention of ethylene glycol monoethyl ether (EGME), was investigated for a wide range of clay fractions and Australian soils. Experimental conditions for optimum precision and convenience of measurement were established. The procedures which utilized a higher vapour pressure of EGME achieved a higher retention of EGME by soils, reached the final condition of measurement more rapidly, and were less dependent on exchangeable cation status of the samples in confirmation of published work with pure smectite. The critical weakness of published procedures for soils is the assumption that the surface area occupied by an EGME molecule on a smectite reference sample can be applied to all soil surfaces. EGME retained per unit area by a range of soil and pure smectites, calculated from total surface area derived from crystal dimensions, and by a range of non-swelling minerals, related to measured BET-N2 areas, varied about fourfold between different mineral groups, and nearly twofold for different smectites. This variation could seriously over- or under-estimate estimates of total surface area, depending on the reference mineral chosen in relation to the mineral species being characterized. Alternatively, for soils free of clay minerals with internal surfaces, an empirical approach based on measured BET-N2 areas of representative soils may be feasible. A consideration of EGME retained in relation to BET-N2 areas may usefully complement X-ray diffraction procedures for characterizing randomly interstratified material in soil clay fractions.

Improved Methods for the Measurement of Total Cell Surface Area in Leaf Mesophyll Tissue

Two improved methods are described for the measurement of the total surface area of mesophyll cells in leaf tissue. The first involves stereological measurements on suspensions of enzymically isolated mesophyll cells; the second involves measurements of the total perimeter of mesophyll cell profiles on transverse sections of the leaf, with allowance for curvature of the cell surfaces by means of theoretically based correction factors. Application of the two methods to the mesophyll tissue of tobacco leaves gave results which were in very good agreement with each other. Both methods avoid the inaccuracies and uncertainties of previous methods for measurement of mesophyll cell surface areas.