Enhanced biodegradation ofo-cresol by activated sludge in the presence of powdered activated carbon

Summary Addition of powdered activated carbon to a continuous-flow activated-sludge culture in a gas-lift bioreactor growing on o-cresol in a mineral-salts medium resulted in a reduction of the effluent o-cresol concentration during steady-state conditions as well as during shock-load conditions. During the latter conditions the activated carbon acted as a buffer. Bioregeneration of loaded activated carbon did occur, resulting in enhanced biodegradation of o-cresol. Adsorption of o-cresol by activated carbon was not sufficient to explain the total difference in effluent o-cresol concentration between the system with activated carbon and the system without activated carbon. Offprint requests to: R. J. de Jonge     

Enhancement of the activated sludge process by activated carbon produced from surplus biological sludge

Surplus biological sludge from wastewater treatment operations was converted into activated carbon and then added to the aerated vessel of an activated sludge process treating phenol and glucose. The addition of activated carbon, either sludge-based or commercial, enhanced phenol removal from 58 to 98.7% and from 87 to 93% for COD with feed concentrations of 100 mg phenol l^–1 and 2500 mg COD l^–1. No differences were found between the activated sludge-activated carbon bench scale continuous reactors operating with either commercial or sludge-based activated carbon in spite of the higher adsorption capacity of the former.     

Purinergic reflex activated by cathartics in the rat

Phenlaxine and bisacodyl were shown to inhibit gastric emptying and motility by activating a reflex arising from the small intestine. This effect produced by the cathartics could not be prevented either by alpha or beta sympatholytic, or by parasympatholytic agents; further it was antagonized by quinine and quinidine, as well as by chloroquine and mepacrine in doses found to suppress gastric motility in untreated animals. The inhibition of gastric motility through cathartics does not appear to be due to an effect on adrenergic or cholinergic pathways but rather to involve a purinergic mechanism.     

A doxorubicin prodrug activated by the staudinger reaction

Much effort has been devoted to prodrug systems that effect drug release at the tumor through enzymatic action. To widen the scope of prodrug therapy, the use of the selective Staudinger reaction as prodrug activator, instead of relying on enzymatic action, was investigated. Doxorubicin was conjugated to a p-azidobenzyl trigger that is cleaved after reacting with the chemical activator, triphenylphosphine. The prodrug activation was confirmed in water, cell growth medium, and serum, using HPLC and LCMS. Next, this approach was tested in a cell proliferation assay with A431 human vulvar skin squamous carcinoma cells. The doxorubicin prodrug was shown to exhibit a 176-fold higher IC50 of 15.1 microM vs 0.086 microM for the parent drug, doxorubicin. Addition of triphenylphosphine (5 x 60 microM in 72 h) to the prodrug in cell culture effected the complete recovery of the activity of the parent drug as evidenced by an IC50 value of 0.074 microM. Furthermore, high levels of triphenylphosphine were tolerated well by the cells. The demonstrated usefulness of the Staudinger reaction in cell culture and its in vivo potential opens up new avenues for prodrug therapy.     

Signaling pathways activated by microorganisms

Invasion of viruses and bacteria is initially sensed by the host innate immune system, and evokes a rapid inflammatory response. Nucleotides from RNA viruses are recognized by retinoic-acid-inducible gene I-like helicases and Toll-like receptors, and this recognition triggers signaling cascades that induce antiviral mediators such as type I interferons. By contrast, Toll-like receptors recognizing bacterial components induce the expression of proinflammatory cytokines. Furthermore, recent studies suggest that viral and bacterial DNA also induce interferons in a Toll-independent mechanism, possibly through unidentified cytoplasmic receptor(s).     

Adsorption of chromium from aqueous solution by activated alumina and activated charcoal

Cr(VI) is considered to be potentially carcinogenic to humans. Removal of Cr(VI) ions from aqueous solution under different conditions was investigated using activated alumina (AA) and activated charcoal (AC) as adsorbents. Batch mode experiments were conducted to study the effects of adsorbent dose, contact time, pH, temperature and initial concentration of Cr(VI). Results showed that the adsorption of Cr(VI) depended significantly on pH and temperature. Equilibrium studies showed that Cr(VI) had a high affinity for AA at pH 4 and AC at pH 2. For AA, maximum adsorption was found at 25 degrees C, indicating exothermic adsorption, while for AC, maximum adsorption was at 40 degrees C. Freundlich and Langmuir adsorption isotherms were also applied and they showed good fits to the experimental data. The results suggest that both AA and AC could be used as effective adsorbents for the removal of Cr(VI) ions.     

Fibrinolytical processes in rabbits activated by the magnetic field

Rabbits were exposed to a constant magnetic field of 0.005 T, 0.1 T and 0.3 T induction for one hour per day each day for a period of four weeks. It was found that the magnetic field increases the rate of fibrinolytical processes. A decrease in fibrinogen concentration, an increase in the level of fibrinogen degradation products and a considerably shorter time of fibrinolysis in plasma were all noted. The magnitude of these processes was proportional to duration of exposure to the magnetic field in action. These date confirms the similar effect observed in other mammalians (guinea pigs, rats). Thus, the application of a static magnetic field of intensity as low as 0.005 T to increase a fibrinolytical processes in the thrombotic therapy seems to be justified.     

Chemicomechanical transduction performed by enzymes activated by polymers

Kinetic models for the mode of action of processive and non-processive DNA-helicases are detailed. Fluxes at the steady state are analyzed, and the random walk of the enzymes on the DNA is studied in connection with the rate constants of the chemical reactions involved in the transformation of substrate to products. Finally, the constants of the kinetic model for the processive helicase are related to the parameters of an analogous viscoelastic model.     

Vimentin is secreted by activated macrophages

Vimentin is a widely expressed intermediate filament protein thought to be involved mainly in structural processes, such as wound healing. We now demonstrate that activated human macrophages secrete vimentin into the extracellular space. The maturation of blood-derived monocytes into macrophages involves several signalling pathways. We show that secretion of vimentin, which is phosphorylated at serine and threonine residues, is enhanced by the phosphatase inhibitor okadaic acid and blocked by the specific protein kinase C inhibitor GO6983. These findings are consistent with previous observations that phosphorylation of vimentin affects its intracellular localization and that vimentin is a substrate for protein kinase C (PKC). We also show that the anti-inflammatory cytokine interleukin-10 (IL-10), which inhibits PKC activity, blocks secretion of vimentin. In contrast, the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-alpha) can trigger secretion of vimentin. Finally, we found that extracellular vimentin is involved in bacterial killing and the generation of oxidative metabolites, two important functions of activated macrophages. These data establish that vimentin is secreted by macrophages in response to pro-inflammatory signalling pathways and is probably involved in immune function.     

PHA production by activated sludge.

The production of polyhydroxyalkanoate by anaerobic-aerobic activated sludge was reviewed concentrating on the biochemical mechanisms and on the trials to increase polyhydroxyalkanoate (PHA) content in activated sludge. The anaerobic aerobic activated sludge system selects microorganisms with the capabilities to couple glycolysis, polyphosphate degradation, and PHA accumulation for anaerobic substrate uptake. Some of the PHA-related metabolisms observed there have not been seen in pure cultures so far. Such metabolisms are the formation of PHA containing 3-hydroxy-2-methylvalerate, and '3-hydroxyvalerate fermentation' in which glucose or glycogen is converted to 3-hydroxyvalerate-rich PHA while yielding energy. The PHA content of activated sludge can be increased up to 62% by applying a microaerophilic-aerobic activated sludge process. PHA production by activated sludge is worth investigation.     

Chloride channels activated by swell can regulate the NADPH oxidase generated membrane depolarisation in activated human neutrophils

Chloride channels activated by swell have important functions in many physiological processes. The phagocyte NADPH oxidase is essential for host defence and it generates superoxide by transferring electrons from the donor NADPH to the acceptor O₂. This electron current, induces a depolarisation of the plasma membrane. In this study, I report that chloride channels activated by swell can counteract the depolarisation induced by the NADPH oxidase. When a chloride conductance was activated by swelling, its inhibition by either 50 μM NPPB or removing external chloride, depolarised the plasma membrane potential to +26 mV ± 3.1 (n = 4) and +40 ± 1 mV (n = 4), respectively. These channels were partially inhibited by the NADPH oxidase inhibitor AEBSF (1 mM) and potently inhibited by ZnCl₂ (3 mM). These currents were not activated by a phosphorylation step and elevations in intracellular calcium did not appear to activate chloride currents similar to those activated by swell.     

A novel GTPase activated by the small subunit of ribosome

The GTPase activity of Escherichia coli YjeQ, here named RsgA (ribosome small subunit-dependent GTPase A), has been shown to be significantly enhanced by ribosome or its small subunit. The enhancement of GTPase activity was inhibited by several aminoglycosides bound at the A site of the small subunit, but not by a P site-specific antibiotic. RsgA stably bound the small subunit in the presence of GDPNP, but not in the presence of GTP or GDP, to dissociate ribosome into subunits. Disruption of the gene for RsgA from the genome affected the growth of the cells, which predominantly contained the dissociated subunits having only a weak activation activity of RsgA. We also found that 17S RNA, a putative precursor of 16S rRNA, was contained in the small subunit of the ribosome from the RsgA-deletion strain. RsgA is a novel GTPase that might provide a new insight into the function of ribosome.     

Classification of the extracellular fields produced by activated neural structures

Background  

Classifying the types of extracellular potentials recorded when neural structures are activated is an important component in understanding nerve pathophysiology. Varying definitions and approaches to understanding the factors that influence the potentials recorded during neural activity have made this issue complex.