Induced Stress on Red Blood Cell Promotes Red Blood Cell-Endothelial Adhesion

Cell and Tissue Biology - Besides disease condition, very few stress stimulants were determined to provoke red blood cell (RBC) adhesion to endothelial cells (EC). However, the possible role of...     

Treatment of low strength complex wastewater using an anaerobic baffled reactor (ABR)

Treatment of a low strength complex wastewater of chemical oxygen demand (COD) around 500mg/L was studied in a 10L capacity laboratory scale anaerobic baffled reactor (ABR). It was operated at hydraulic retention times (HRTs) of 20, 15, 10, 8 and 6h. Corresponding organic loading rates (OLRs) were 0.6, 0.8, 1.2, 1.5 and 2kg COD/m(3)d. At every HRT (or OLR), pseudo steady state (PSS) was achieved. Even at maximum OLR of 2kg COD/m(3)d, COD and biochemical oxygen demand (BOD) removals exceeded 88%. Removal of particulate fraction of organics was found to be greater than soluble fraction. Compartment-wise studies of various parameters revealed that if the OLR was larger, the number of initial compartments played significant role in the removal of organics. The values of volatile fatty acids (VFA) demonstrated that hydrolysis and acidogenesis were the main biochemical activities in the initial few compartments. Based on the tracer studies, dead space in the ABR was found to range from 23% to 34%. The flow pattern in the ABR was classified as intermediate between plug flow and perfectly mixed flows. Observations from scanning electron micrographs (SEM) also suggested that distinct phase separation takes place in an ABR. Study of organic and hydraulic shock loads revealed that ABR was capable of sustaining the type of shock loads generally experienced at a sewage treatment plant (STP).     

Striatal-enriched protein-tyrosine phosphatase (STEP) regulates Pyk2 kinase activity

Proline-rich tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family and is highly expressed in brain and hematopoietic cells. Pyk2 plays diverse functions in cells, including the regulation of cell adhesion, migration, and cytoskeletal reorganization. In the brain, it is involved in the induction of long term potentiation through regulation of N-methyl-d-aspartate receptor trafficking. This occurs through the phosphorylation and activation of Src family tyrosine kinase members, such as Fyn, that phosphorylate GluN2B at Tyr(1472). Phosphorylation at this site leads to exocytosis of GluN1-GluN2B receptors to synaptic membranes. Pyk2 activity is modulated by phosphorylation at several critical tyrosine sites, including Tyr(402). In this study, we report that Pyk2 is a substrate of striatal-enriched protein-tyrosine phosphatase (STEP). STEP binds to and dephosphorylates Pyk2 at Tyr(402). STEP KO mice showed enhanced phosphorylation of Pyk2 at Tyr(402) and of the Pyk2 substrates paxillin and ASAP1. Functional studies indicated that STEP opposes Pyk2 activation after KCl depolarization of cortical slices and blocks Pyk2 translocation to postsynaptic densities, a key step required for Pyk2 activation and function. This is the first study to identify Pyk2 as a substrate for STEP.     

nNOS mediated mitochondrial injury in LPS stimulated oligodendrocytes

Products of inflammation and the activation of nitric oxide synthase have been proposed as a mechanism of oligodendrocyte injury in CNS inflammation. There are currently three well described and known isoforms of NOS. Of these, neuronal NOS (nNOS) was initially discovered in neurons, endothelial NOS (eNOS) in vascular endothelium, while the inducible form of NOS (iNOS) is known to be activated in oligodendrocytes, astrocytes and microglia. We examined the activation of nNOS and the down stream effects of NO production in oligodendrocyte precursor cells (OPC) and MO3.13 cell line following culture with LPS. Our studies show that both MO3.13 cells and OPC are susceptible to the cellular injury resulting from LPS mediated activation and NO production. Activation of the TLR4 receptor with LPS led to decrease in cell viability that was associated with loss of mitochondrial membrane potential and impaired enzymatic activity of complex I and complex IV protein of the respiratory chain. 7-NI, a known inhibitor of nNOS was able to rescue of cells from LPS mediated mitochondrial damage. Loss of mitochondrial function was associated with translocation of cytochrome C and apoptosis inducing factor to the cytosol, setting the stage for apoptosis. Phosphorylation of PI3K and Akt was required for optimal activation of NOS. These studies provide a biochemical basis for nNOS mediated oligodendrocyte injury and suggest similar mechanisms may play a role in diseases characterized by oligodendrocyte loss and demyelination.     

Formation and dynamic alterations of horizontal microdomains in sperm membranes during progesterone-induced acrosome reaction

A peptidomics approach was applied to determine the peptides in the larval central nervous system of the grey flesh fly, Neobellieria bullata. Fractions obtained by high performance liquid chromatography were analysed by MALDI-TOF and ESI-Q-TOF mass spectrometry. This provided biochemical evidence for the presence of 18 neuropeptides, 11 of which were novel Neobellieria peptides. Most prominently present were the FMRFamide-related peptides: 7 FMRFamides, 1 FIRFamide, and Neb-myosuppressin. The three putative capa-gene products Neb-pyrokinin and the periviscerokinins Neb-PVK-1 and -2 were detected, as well as another pyrokinin. This Neb-PK-2 was also present in the ring gland along with corazonin, Neb-myosuppressin, and Neb-AKH-GK, an intermediate processing product of the adipokinetic hormone. Furthermore, the central nervous system contained Neb-LFamide, proctolin, and FDFHTVamide, designated as Neb-TVamide. With this study, we considerably increased our knowledge of the neuropeptidome of the pest fly N. bullata, which is an important insect model for physiological research.     

Titanium Dioxide Nanoparticles Trigger Loss of Function and Perturbation of Mitochondrial Dynamics in Primary Hepatocytes

Titanium dioxide (TiO₂) nanoparticles are one of the most highly manufactured and employed nanomaterials in the world with applications in copious industrial and consumer products. The liver is a major accumulation site for many nanoparticles, including TiO₂, directly through intentional exposure or indirectly through unintentional ingestion via water, food or animals and increased environmental contamination. Growing concerns over the current usage of TiO₂ coupled with the lack of mechanistic understanding of its potential health risk is the motivation for this study. Here we determined the toxic effect of three different TiO₂ nanoparticles (commercially available rutile, anatase and P25) on primary rat hepatocytes. Specifically, we evaluated events related to hepatocyte functions and mitochondrial dynamics: (1) urea and albumin synthesis using colorimetric and ELISA assays, respectively; (2) redox signaling mechanisms by measuring reactive oxygen species (ROS) production, manganese superoxide dismutase (MnSOD) activity and mitochondrial membrane potential (MMP); (3) OPA1 and Mfn-1 expression that mediates the mitochondrial dynamics by PCR; and (4) mitochondrial morphology by MitoTracker Green FM staining. All three TiO₂ nanoparticles induced a significant loss (p < 0.05) in hepatocyte functions even at concentrations as low as 50 ppm with commercially used P25 causing maximum damage. TiO₂ nanoparticles induced a strong oxidative stress in primary hepatocytes. TiO₂ nanoparticles exposure also resulted in morphological changes in mitochondria and substantial loss in the fusion process, thus impairing the mitochondrial dynamics. Although this study demonstrated that TiO₂ nanoparticles exposure resulted in substantial damage to primary hepatocytes, more in vitro and in vivo studies are required to determine the complete toxicological mechanism in primary hepatocytes and subsequently liver function.