Color and organic compounds removal from secondary effluent of landfill leachate with a novel inorganic polymer coagulant

Emerging contaminants in landfill leachate are causing environmental concerns due to their adverse impacts on the aquatic environment. The most popular biological process is mostly the first stage in combination with additional physical-chemical process. Current post-treatments are limited by high operating costs, low treatment efficiencies, or sensitive operating conditions. Poly-aluminium(III)-magnesium(II)-sulfate (PMAS in brief) is used to remove color and organic compounds in secondary effluent of landfill leachate. More than 40 kinds of organic matters in the secondary effluent are identified and 10 of them belong to the Black List of environmental preferred controlled pollutants considered by EPA of USA or China. Removals of COD, BOD(5), UV(254) and color by coagulation with PAMS can reach above 60%, 55%, 85% and 85% respectively under the optimum conditions. The species of alkyl, alkene, acyclic alcohol and acyclic acyl amine are efficiently removed (about 85%), with some of them removed completely, while the species of acid, ester and ketone are mostly removed (about 65%) and such matters with benzene ring as aromatic hydrocarbon, hydroxybenzene, aromatic alcohol, aromatic acyl amine are partially removed (about 50%). Organic pollutants in the secondary effluent are greatly removed with high efficiency here, which greatly weakens its pollution extent.

Analgesic effect of electroacupuncture on complete Freund's adjuvant-induced inflammatory pain in mice: a model of antipain treatment by acupuncture in mice

Electroacupuncture (EA) was applied bilaterally to the acupoints of Zu-san-li (ST-36) and Kun-lun (BL-60) in the hindlimbs of mice. The therapeutic effect of EA on inflammatory pain induced by an ipsilateral injection of complete Freund's adjuvant (CFA) into the right paw of the mouse was investigated in this study. The time of paw-withdrawal latency (PWL) was used as an indicator for judging the intensity of the pain induced by the CFA injection. The EA effects were divided into immediate (PWL tests within 2 h after EA treatment) and cumulative (PWL tests during and after repetitive EA treatments for 3 weeks) effects. As immediate effects, PWL was significantly shortened in the CFA-injected paw, but was again prolonged 20 min after an EA treatment and lasted until 30 min after. As cumulative effects, PWL was significantly shortened in the CFA-injected paw, but recovered from the 2nd to the 8th day during repetitive EA treatments. No such effects could be observed after sham EA treatment, which resulted in behavior similar to that in untreated animals. These results demonstrate that the CFA-induced inflammatory pain in mice is an ideal model system for the investigation of EA effects and may serve as a valuable reference for the clinical treatment of inflammatory pain in human beings. Furthermore, the mouse pain model opens the possibility to apply the investigation also to transgenic mice.

Modulation of Na(+),K(+) pumping and neurotransmitter uptake by beta-amyloid

Micromolar concentrations of beta-amyloid (Abeta), a 40/42-amino-acid-long proteolytic fragment (Abeta(1-40/42)) of the amyloid precursor protein, was shown previously to play a crucial role in pathogenesis of Alzheimer's disease. We used the Xenopus oocyte expression system to investigate specific effects of micromolar concentrations of Abeta(1-42) on the neurotransmitter transporters for gamma-aminobutyric acid (GABA), GAT1, and for the excitatory amino acid glutamate, EAAC1, which are driven by the transmembrane Na(+) gradient that is regulated by the Na(+),K(+)-ATPase. Brief treatment with Abeta(1-42), up to 80 min, leads to a significant inhibition of ion translocation by the Na(+),K(+)-ATPase (30-40%); also glutamate uptake is inhibited (20%) while GABA uptake is not affected. Since reduced glutamate uptake will result in elevated, neurotoxic concentrations of extracellular glutamate, we investigated the effects of Abeta(1-42) and the smaller fragments, Abeta(12-28) and Abeta(25-35), on EAAC1 in more detail. Prolonged incubation in 1 microM Abeta(1-42) leads to further, strong inhibition of glutamate uptake and EAAC1-mediated current (after 4 h inhibition amounts to more than 80%). Abeta(12-28) is less effective with 50% inhibition after 4 h of incubation at 20 microM. Abeta(1-42) and Abeta(12-28) affect EAAC1-mediated current to a similar extent as the rate of glutamate uptake. The effects on EAAC1-mediated current are irreversible if Abeta were applied for longer time periods. Peptides directly microinjected into the oocyte are ineffective suggesting that the observed effect were mediated by extracellular proteins. Abeta(25-35) hardly affects EAAC1-mediated current or glutamate uptake. The results demonstrate that Abeta specifically inhibits the Na(+),K(+) pump and EAAC1. The domain between amino acids 12 and 28 of Abeta seems to play a crucial role for inhibition of EAAC1. The inhibition of EAAC1 by neurotoxic, elevated extracellular glutamate levels may contribute to Alzheimer's pathogenesis.

[Cloning and analyzing of members of excitatory amino acid transporter family from neonatal mouse brain]

Excitatory amino acid transporter family (EAAT) contains several structure-related membrane proteins. They are essential for the removal of glutamate released from pre-synaptic terminal to terminate its action of synaptic transduction and maintaining the normal concentration of neurotransmitters in nerve system. To study these proteins in single animal model, we cloned several members of EAAT family, named mGLAST-1, mGLT-1, mEAAC1 and mASCT1, from a neonatal mouse brain cDNA library. The cDNA sequence of mASCT1 was firstly reported in mouse, it is composed of 3787 bp which has an open reading frame (ORF) encoding a protein of 532 amino acid residues. The mASCT1 protein was expressed in Xenopus oocyte and the function was characterized by 3H-Ser uptaking. The homology between human ASCT1 and mouse ASCT1 is 89.3%. The DNA sequence data shows the variance in length and composition exists in the sequence of 5'UTR and 3'UTR of mRNA in the family members of EAAT. This phenomenon may indicate a post-transcription regulation mechanism might exist in the gene expression of mouse EAAT family members.

Val 70, Phe 72 and the last seven amino acid residues of C-terminal are essential to the function of norepinephrine transporter

The norepinephrine transporter(NET) is a member of the Na+/Cl- dependent neurotransmitter transporter family and constitutes the target of several clinically important antidepressants. To delineate the critical amino acid residues and the function of C-terminal in regulating transport activity of NET, here we constructed two site mutants (V70F, F72V; V70I, F72V) and one C-terminal truncated mutant (delta 611-617). The wild type and mutants of NET were expressed in Xenopus oocytes by injection of their cRNA. We found that all of these mutants lost their transport activity. These results indicate that the amino acid residues of V70 and F72, and the last seven amino acids of C-terminal are essential to the transport activity of NET.

Effects of taurine on L-type voltage-dependent Ca2+ channel in rat cardiomyocytes infected with coxsackievirus B3

AIM

To study the effects of taurine on L-type voltage-dependent Ca2+ channel (VDCC) in adult rat cardiomyocytes infected with coxsackievirus B3 (CVB3).

METHODS

Whole-cell Ca2+ current of L-type VDCC was obtained by patch-clamp techniques.

RESULTS

The density of L-type Ca2+ current was 4.1 +/- 0.8 pA/pF in normal cardiomyocytes, but increased to 4.9 +/- 1.4 pA/pF with CVB3 infection. At 16 mmol.L-1, taurine decreased the density to 3.5 +/- 0.5 pA/pF in normal cardiomyocytes, and to 3.8 +/- 0.8 pA/pF in CVB3-infected cardiomyocytes. In addition, CVB3 shifted the membrane potential depolarizing to peak current (Vp) from 8 +/- 8 mV to 5 +/- 3 mV which could also be reverted to 8 +/- 4 mV by taurine.

CONCLUSION

Taurine inhibited the increase of Ca2+ inflow through L-type VDCC and normalized the decreased Vp induced by CVB3 infection. The effect of taurine on L-type VDCC was the mechanism of taurine attenuating the intracellular Ca2+ accumulation and abnormal electric activities induced by CVB3 infection.

[The expression of kainate and GABA receptors in oocytes of Bufo bufo gargarizans]

Oocytes of Bufo bufo gargarizans were used as an expression system for analyzing structure of exogenous membrane protein and their functions. Poly (A)+ mRNA isolated from rat brain was injected into Toad (Bufo bufo gargarizans) oocytes (50 ng/oocyte). Rat brain kainic acid and gamma-aminobutyric acid(GABA) receptors expressed by the injected mRNA were integrated in the oocyte membrane 48 h after the injection at 19 degrees C. Membrane currents induced by kainic acid (5 x 10(-5) mol/L) and GABA (10(-4) mol/L) were 294.0 +/- 6.4 nA (n = 5) and 309.5 +/- 4.9 nA (n = 4) respectively. The kainic acid induced current reached its maximum value at about 10(-3) mol/L. Moreover, it was observed that the 36Cl- influx of the oocytes microinjected with mRNA was one-fold more rapid than the control oocytes. These results indicate that the oocytes of Bufo bufo gargarizans as those of Xenopus laevis can be used to express membrane proteins (receptors & transports) to acquire their proper functions from exogenous mRNA.

[A voltage-dependent potassium channel of outward rectifier type in plasma membrane of oocyte from toad, Bufo bufo gargarizans]

Membrane properties of the fully-grown oocytes from toad, Bufo bufo gargarizans, were studied by using voltage-clamp technique. It was found that a sustained outward current was elicited by membrane depolarization to -30 mV or more positive value. The increase of the current was nearly proportional to the degree of depolarization. The peak value of the current ranged 2-5 microA at a membrane potential of 20 mV in oocytes from different toads. The current was inhibited by antagonists of potassium channel, TEA and 4-AP. The concentration of TEA capable of inhibiting half of the current was 2.6 mmol/L. Chloride channel antagonist 9-AC (2.5 mmol/L) had no effect on the current. Triple the extracellular calcium concentration did not show any effect either. The reversal potential of the current varied with an increase of 47.3 mV per decade change of the extracellular potassium concentration. Changing extracellular concentration of sodium or chloride did not shift the reversal potential. It was concluded that the outward current was a voltage-activated potassium current. The voltage-dependent potassium current decreased after treatment of the oocytes with progesterone to a state of maturation. A large decrease of the current (to about 1/20 of the control) occurred to the oocytes obtained from hibernating toads while a less striking decrease of the current (to about 1/3 of the control) was observed in the oocytes from toads all year round reared at 25-30 degrees C.

Characteristics of the Na+/K+-ATPase from Torpedo californica expressed in Xenopus oocytes: a combination of tracer flux measurements with electrophysiological measurements

The Na+/K+-ATPase from electroplax of Torpedo californica was incorporated into the plasma membrane of Xenopus oocytes by microinjection of mRNA coding for the alpha- and beta-subunit of the enzyme; the mRNAs were obtained by in vitro translation of cloned cDNAs (Noguchi et al. (1988) FEBS Lett. 225, 27-32). (1) Measurements of ouabain-sensitive membrane current revealed that the Na+/K+-ATPase of Torpedo is less sensitive to ouabain than the endogenous enzyme. (2) The ouabain-sensitive membrane currents in mRNA-injected oocytes exhibit similar voltage dependence as the currents generated by the endogenous ATPase of Xenopus oocytes; in particular, the current-voltage relation exhibits a maximum and a negative slope at potentials more positive than +20 mV. (3) A maximum can also be detected if the rate of 22Na+ efflux is determined under different voltage-clamp conditions. If membrane current and rate of Na+2 efflux are determined simultaneously, a voltage-independent ratio between current and flux is obtained suggesting voltage-independent Na+-K+ stoichiometry. The data are compatible with a 3Na+-2K+ stoichiometry.