Superinfection by discordant subtypes of HIV-1 does not enhance the neutralizing antibody response against autologous virus

Recent studies have demonstrated that both the potency and breadth of the humoral anti-HIV-1 immune response in generating neutralizing antibodies (nAbs) against heterologous viruses are significantly enhanced after superinfection by discordant HIV-1 subtypes, suggesting that repeated exposure of the immune system to highly diverse HIV-1 antigens can significantly improve anti-HIV-1 immunity. Thus, we investigated whether sequential plasma from these subjects superinfected with discordant HIV-1 subtypes, who exhibit broad nAbs against heterologous viruses, also neutralize their discordant early autologous viruses with increasing potency. Comparing the neutralization capacities of sequential plasma obtained before and after superinfection of 4 subjects to those of matched plasma obtained from 4 singly infected control subjects, no difference in the increase in neutralization capacity was observed between the two groups (p = 0.328). Overall, a higher increase in neutralization over time was detected in the singly infected patients (mean change in IC(50) titer from first to last plasma sample: 183.4) compared to the superinfected study subjects (mean change in IC(50) titer from first to last plasma sample: 66.5). Analysis of the Breadth-Potency Scores confirmed that there was no significant difference in the increase in superinfected and singly infected study subjects (p = 0.234). These studies suggest that while superinfection by discordant subtypes induces antibodies with enhanced neutralizing breadth and potency against heterologous viruses, the potency to neutralize their autologous viruses is not better than those seen in singly infected patients.     

Dynamic and structural scalings of the complexation between pDNA and bPEI in semidilute and low‐salt solutions

Using a combination of static and dynamic laser light scattering, we investigated the complexation of a supercoiled plasmid DNA (pDNA, 10⁴ bp) and a branched polyethyleneimine (bPEI, M_w = 25 kD) in semidilute and low‐salt aqueous solutions. Our results unearth some scaling laws for dynamic and structural properties of the resultant complexes (polyplexes) with different bPEI:pDNA (N:P) molar ratios. Namely, the average scattering intensity (<I>) and the average linewidth of the Rayleigh peak (<Γ>) are scaled to the scattering vector (q) as <I> ∝ q or <Γ> ∝ q, where α_S and α_D are two N:P dependent scaling exponents. The N:P ratio strongly affects the complexation. When N:P < 2.0, the motions of the negatively charged and extended pDNA chains and the polyplexes are highly correlated so that they behave like a transient network with a fractal dimension. As the N:P ratio increases, nearly all of pDNA chains condensed and the overall charge of the polyplexes reverses to slightly positive, resulting in a turbid dispersion of large loose aggregates made of smaller, but more compact, polyplexes. Further increase of N:P finally disrupts large loose aggregates, leading to a homogeneous transparent dispersion of the polyplexes. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 571–577, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Developmental regulation and cellular distribution of human cytosolic malate dehydrogenase (MDH1)

Human cyotsolic malate dehydrogenase (MDH1) is important in transporting NADH equivalents across the mitochondrial membrane, controlling tricarboxylic acid (TCA) cycle pool size and providing contractile function. Cellular localization studies indicate that MDH1 mRNA expression has a strong tissue-specific distribution, being expressed primarily in cardiac and skeletal muscle and in the brain, at intermediate levels in the spleen, kidney, intestine, liver, and testes and at low levels in lung and bone marrow. The observed MDH1 localizations reflect the role of NADH in the support of a variety of functions in different organs. These functions are primarily related to aerobic energy production for muscle contraction, neuronal signal transmission, absorption/resorption functions, collagen-supporting functions, phagocytosis of dead cells, and processes related to gas exchange and cell division. During neonatal development, MDH1 is expressed in human embryonic heart as early as the 3rd month and then is over-expressed from the 5th month until the birth. The expression of MDH1 is maintained in the adult heart but is not present in levels as high as in the fetus. Finally, over-expression of MDH1 is found in left ventricular cardiac muscle of dilated cardiomyopathy (DCM) patients when contrasted to the diseased non-DCM and normal heart muscle by in situ hybridization and Western blot. These observations are compatible with the activation of glucose oxidation in relatively hypoxic environments of fetal and hypertrophied myocardium.     

Crystallization and preliminary x-ray crystallographic data of dienelactone hydrolase from Pseudomonas sp. B13

Dienelactone hydrolase (EC 3.1.1.45) from Pseudomonas sp. B13 has been crystallized in a form suitable for high resolution x-ray diffraction study. The crystals are orthorhombic, the space group being P212121, with unit cell dimensions a = 48.9 A, b = 71.2 A, and c = 77.5 A. There appears to be 1 molecule in the asymmetric unit.     

Glial tumor cells deficient in thymidine kinase: isolation and characterization

Rat astrocytoma cells were treated with the mutagen N-methyl-N′-nitro-N-nitrosoguanidine and grown in the presence of high concentrations of the thymidine analog 5-bromo-2′-deoxyuridine. A surviving clone, designated C₆TK⁻, lacked thymidine kinase but exhibited differentiated functions such as catecholamine-sensitive adenylate cyclase activity, cortisol-inducible glycerol-1-phosphate dehydrogenase activity, and S-100 protein biosynthesis.     

Systematic Analysis of In Vitro Cell Rolling Using a Multi-well Plate Microfluidic System

A major challenge for cell-based therapy is the inability to systemically target a large quantity of viable cells with high efficiency to tissues of interest following intravenous or intraarterial infusion. Consequently, increasing cell homing is currently studied as a strategy to improve cell therapy. Cell rolling on the vascular endothelium is an important step in the process of cell homing and can be probed in-vitro using a parallel plate flow chamber (PPFC). However, this is an extremely tedious, low throughput assay, with poorly controlled flow conditions. Instead, we used a multi-well plate microfluidic system that enables study of cellular rolling properties in a higher throughput under precisely controlled, physiologically relevant shear flow^1,2. In this paper, we show how the rolling properties of HL-60 (human promyelocytic leukemia) cells on P- and E-selectin-coated surfaces as well as on cell monolayer-coated surfaces can be readily examined. To better simulate inflammatory conditions, the microfluidic channel surface was coated with endothelial cells (ECs), which were then activated with tumor necrosis factor-α (TNF-α), significantly increasing interactions with HL-60 cells under dynamic conditions. The enhanced throughput and integrated multi-parameter software analysis platform, that permits rapid analysis of parameters such as rolling velocities and rolling path, are important advantages for assessing cell rolling properties in-vitro. Allowing rapid and accurate analysis of engineering approaches designed to impact cell rolling and homing, this platform may help advance exogenous cell-based therapy.     

BP-ANN for Fitting the Temperature-Germination Model and Its Application in Predicting Sowing Time and Region for Bermudagrass

Temperature is one of the most significant environmental factors that affects germination of grass seeds. Reliable prediction of the optimal temperature for seed germination is crucial for determining the suitable regions and favorable sowing timing for turf grass cultivation. In this study, a back-propagation-artificial-neural-network-aided dual quintic equation (BP-ANN-QE) model was developed to improve the prediction of the optimal temperature for seed germination. This BP-ANN-QE model was used to determine optimal sowing times and suitable regions for three Cynodon dactylon cultivars (C. dactylon, ‘Savannah’ and ‘Princess VII’). Prediction of the optimal temperature for these seeds was based on comprehensive germination tests using 36 day/night (high/low) temperature regimes (both ranging from 5/5 to 40/40°C with 5°C increments). Seed germination data from these temperature regimes were used to construct temperature-germination correlation models for estimating germination percentage with confidence intervals. Our tests revealed that the optimal high/low temperature regimes required for all the three bermudagrass cultivars are 30/5, 30/10, 35/5, 35/10, 35/15, 35/20, 40/15 and 40/20°C; constant temperatures ranging from 5 to 40°C inhibited the germination of all three cultivars. While comparing different simulating methods, including DQEM, Bisquare ANN-QE, and BP-ANN-QE in establishing temperature based germination percentage rules, we found that the R² values of germination prediction function could be significantly improved from about 0.6940–0.8177 (DQEM approach) to 0.9439–0.9813 (BP-ANN-QE). These results indicated that our BP-ANN-QE model has better performance than the rests of the compared models. Furthermore, data of the national temperature grids generated from monthly-average temperature for 25 years were fit into these functions and we were able to map the germination percentage of these C. dactylon cultivars in the national scale of China, and suggested the optimum sowing regions and times for them.     

PFTK1 interacts with cyclin Y to activate non-canonical Wnt signaling in hepatocellular carcinoma

PFTK1 is a Cdc2-related protein kinase that is frequently upregulated in human hepatocellular carcinoma (HCC) where it correlates with metastatic features and motile phenotypes. To understand the modulated pathway underlining the PFTK1 action, here we show a physical interaction between PFTK1 and cyclin Y (CCNY) in promoting noncanonical Wnt signaling. In HCC cells, we found PFTK1 forms a direct complex with CCNY, and together readily upregulate key components of Wnt signaling (Dvl2 and Naked1). Exogenous expression of PFTK1 and CCNY activated Rho GTPases, which are known targets of the noncanonical path. In line with Rho GTPases activation, we also found marked actin polymerizations in cells with PFTK1–CCNY co-expressions. Our findings highlight a PFTK1–CCNY complex in activating noncanonical Wnt signaling in HCC cells.     

An agglutinin with mitogenic and antiproliferative activities from the mushroom Flammulina velutipes

A hemagglutinin with a molecular mass of 12 kDa was isolated from the fruiting bodies of the mushroom Flammulina velutipes. Its molecular mass is similar to that of the fungal immunomodulatory protein isolated from F. velutipes (FIP-fve) with ice-cold 5% acetic acid and 50 mM 2-mercaptoethanol as extraction medium and to that of the larger 12 kDa subunit of F. velutipes lectin isolated with phosphate buffer as extraction medium. Its hemagglutinating activity cannot be inhibited by a variety of carbohydrates tested. The activity is stable between pH 4 and pH 11. Loss in activity occurred when the temperature is raised to 60 C and 70 C. Activity is indiscernible at and above 80 C. Its N-terminal sequence shows differences from that of FIP-fve. F. velutipes hemagglutinin stimulates [3H-methyl] thymidine uptake by mouse splenocytes. It inhibits proliferation of leukemia L1210 cells with an IC50 of 13 microM.