Mechanisms of Long Non-Coding RNAs in Biological Characteristics and Aerobic Glycolysis of Glioma

Glioma is the most common and aggressive tumor of the central nervous system. The uncontrolled proliferation, cellular heterogeneity, and diffusive capacity of glioma cells contribute to a very poor prognosis of patients with high grade glioma. Compared to normal cells, cancer cells exhibit a higher rate of glucose uptake, which is accompanied with the metabolic switch from oxidative phosphorylation to aerobic glycolysis. The metabolic reprogramming of cancer cell supports excessive cell proliferation, which are frequently mediated by the activation of oncogenes or the perturbations of tumor suppressor genes. Recently, a growing body of evidence has started to reveal that long noncoding RNAs (lncRNAs) are implicated in a wide spectrum of biological processes in glioma, including malignant phenotypes and aerobic glycolysis. However, the mechanisms of diverse lncRNAs in the initiation and progression of gliomas remain to be fully unveiled. In this review, we summarized the diverse roles of lncRNAs in shaping the biological features and aerobic glycolysis of glioma. The thorough understanding of lncRNAs in glioma biology provides opportunities for developing diagnostic biomarkers and novel therapeutic strategies targeting gliomas.

Comparisons between experimental and morphometric water vapor conductance in the eggs of extant birds and crocodiles: implications for predicting nest type in dinosaurs

Estimates of water vapor conductance for the eggs (i.e., diffusive capacity of eggshell; Gh2o, mg H2O·day−1·Torr−1) of extinct archosaur species have been used to infer their nest type (i.e., covered vs. open) because experimental Gh2o values for living archosaur species appear to reflect nest type. The methods used to derive Gh2o for fossil eggs (eggshell morphometrics) differs from that for extant eggs (experimental measurements), and it remains unknown if these two methods are comparable or if morphometric Gh2o values correspond to nest type. Although previous studies assumed that Gh2o values derived from the two methods were comparable, this assumption has not been statistically evaluated in a large sample size that includes both crocodiles and birds. Here, Gh2o values for over 100 species of living archosaurs for both morphometric and experimental methods were compiled and compared using statistical analyses. Results showed that although experimental and morphometric Gh2o values are significantly correlated, there is disagreement between the methods particularly apparent in small eggs, likely due to systematic errors. These results suggest that morphometric and experimental Gh2o of living species are not necessarily comparable, although the reason for the discrepancy remains uncertain. Thus, direct comparisons between morphometric Gh2o of dinosaurs and experimental Gh2o of living species should be avoided when inferring the nest type for dinosaurs.

MATHEMATICAL FRAMEWORK OF THE WELL PRODUCTIVITY INDEX FOR FAST FORCHHEIMER (NON-DARCY) FLOWS IN POROUS MEDIA

Motivated by the reservoir engineering concept of the well Productivity Index, we introduced and analyzed a functional, denoted as "diffusive capacity", for the solution of the initial-boundary value problem (IBVP) for a linear parabolic equation.21This IBVP described laminar (linear) Darcy flow in porous media; the considered boundary conditions corresponded to different regimes of the well production. The diffusive capacities were then computed as steady state invariants of the solutions to the corresponding time-dependent boundary value problem.Here similar features for fast or turbulent nonlinear flows subjected to the Forchheimer equations are analyzed. It is shown that under some hydrodynamic and thermodynamic constraints, there exists a so-called pseudo steady state regime for the Forchheimer flows in porous media. In other words, under some assumptions there exists a steady state invariant over a certain class of solutions to the transient IBVP modeling the Forchheimer flow for slightly compressible fluid. This invariant is the diffusive capacity, which serves as the mathematical representation of the so-called well Productivity Index. The obtained results enable computation of the well Productivity Index by resolving a single steady state boundary value problem for a second-order quasilinear elliptic equation. Analytical and numerical studies highlight some new relations for the well Productivity Index in linear and nonlinear cases. The obtained analytical formulas can be potentially used for the numerical well block model as an analog of Piecemann.

Transport Phenomena in Smectite Clay Explained by Considering Microstructural Features

ABSTRACTThe microstructure of clays controls their transport properties. This is concluded from comparing microstructural parameter data with the hydraulic conductivity and the ion diffusive transport capacity. Illitic clays contain a number of interacting open voids with a high flow capacity while natural smectite-rich clays are more homogeneous with smaller voids and a lower hydraulic conductivity than illitic clays with the same density. Artificially prepared smectitic clays, like those proposed for embedding canisters with highly radioactive waste, have a higher conductivity than natural clays with the same smectite content because the microstructural homogeneity of the artificial clays is less good.The anion diffusive transport capacity of smectite-rich clays with high density is much lower than that of clays with low density in contrast to the cation diffusive capacity. This is explained by using quantitative microstructural data.

Determinants of maximal exercise VO2 during single leg knee-extensor exercise in humans

Previously, a reduction in fractional inspired O2 (FIO2) during dynamic exercise of the human quadriceps muscles of one leg resulted in increased muscle blood flow (Q) and a fall in femoral venous O2 tension (PO2) but no change in peak O2 uptake (VO2). These data can be interpreted as reflecting an increase in muscle O2 diffusive capacity (DO2) in hypoxia or, alternatively, that maximum O2 uptake (VO2max) was not reached for these muscles when air was breathed, in which case the theory of diffusion limitation to VO2max is not applicable to these data. Therefore, the primary goal of this study was to test the hypothesis that VO2max would be reduced in hypoxia as a result of the decreased O2 supply and a constant diffusional conductance from blood to exercising muscle. To resolve this, five trained men were studied performing single leg incremental knee-extensor exercise to VO2max while breathing air (N) and again while breathing 12% O2 (H). The maximum work rate (WRmax) was 30–50 W greater and produced even greater associated maximum leg Q (N = 9.1 +/- 0.61 and H = 8.2 +/- 0.65 l/min, P < 0.05) and leg O2 than in previous studies. Hypoxia reduced quadriceps muscle VO2max (N = 1.4 +/- 0.1 and H = 1.1 +/- 0.1 l/min, P < 0.05). In the two conditions the relationships between 1) measured femoral venous PO2 (N = 18 +/- 0.5 and H = 13 +/- 0.5 Torr) and VO2max and 2) calculated mean capillary PO2 (N = 37 +/- 0.4 and H = 28 +/- 0.8 Torr) and VO2max were each one of proportionality.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of lymphatic protein flux data. V. Unique PS products and sigma dS at low lymph flows

The selectivity of the capillary membrane to protein (osmotic reflection coefficient, sigma d) can be measured at high transcapillary volume flow when the capillary membrane can be considered as a true sieve. However, the diffusive capacity of the membrane (permeability-surface area product, PS) for macromolecules has not been directly measured, only estimated by assuming that transcapillary volume flow was zero. Based on unique properties of the Peclet number, a parameter that describes the ratio of solute convective flux relative to diffusive capacity, we have developed three new techniques using lymph protein fluxes to estimate a unique PS product that is independent of transcapillary fluid flux. Two of these techniques require a measure of sigma d when the ratio of protein concentration in lymph relative to plasma is equal to (1- sigma d), which occurs at high capillary filtration rates. However, the third method allows both sigma d and the PS product to be determined at relatively low lymph flow rates, eliminating the need for high capillary pressures to determine sigma d. For each protein, these techniques yield an estimate of PS and sigma d for the total membrane. However, by analysis of several different sized proteins and estimation of small- and large-pore volume flows, sigma d and PS can be determined separately for the small- and large-pore pathways. These techniques for estimating sigma d and PS were evaluated by modeling the total solute flux of albumin and immunoglobulins G and M in a heteroporous membrane.

The diffusion porometer

Various devices have from time to time been described for investigating the movement of stomata. These depend for their action on the rate of flow of air under uniform pressure drawn or pushed through the stomata; the measure of stomatal aperture is thus some function of the rate of flow. This principle was first used by Dutrochet (1832), and by Müller, in 1872, and an apparatus, using a cup attached to a leaf, was constructed by Darwin and Pertz in 1912. Self-recording porometers on the principle of Darwin’s porometer were perfected by Balls (1912), Knight (1915, 1922), Laidlaw and Knight (1916), and Neilson-Jones (1914). For use with amphistomatous leaves a double porometer has been described by Leick (1928). All the instruments mentioned measure the rate of flow of the gas. Recently a porometer has been described by Gregory and Pearse (1934) in which the fall in pressure of the air on passing through the leaf is the basis of measurement and nearly instantaneous readings of stomatal aperture are thus possible. The conversion of these measures of stomatal aperture into terms of change of diffusive capacity presents a problem which has not yet been completely resolved by experimental methods. It would therefore appear that a method of direct estimation of the diffusive capacity of the stomata is very desirable. The present paper describes an apparatus which makes possible a direct and continuous measure of the change in the diffusive capacity of stomata during their opening and closing.