Apocynum venetum leaf extract, an antihypertensive herb, inhibits rat aortic contraction induced by angiotensin II: a nitric oxide and superoxide connection.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves extract of Apocynum venetum (AVLE), also known as "luobuma", have long been used in traditional Chinese medicine to treat hypertension and depression in parts of China and it has been shown to possess anti-oxidant and anti-lipid peroxidation effects. AVLE (10 µg/ml) has been reported to have a long-lasting endothelium-dependent relaxant effect and this effect has been proposed to be due to its nitric oxide(NO)-releasing and superoxide anion(SOA)-scavenging properties. AIM OF THE STUDY: The present study seeks to evaluate the differential actions of AVLE extract between Ang II- and PE-induced vasoconstriction and the involvement of superoxide anions. MATERIALS AND METHODS: Single dose of Ang II (100 nM and 1 nM)- or PE (0.1 µM)-induced contraction were assessed in both endothelium-intact and -denuded aortic rings after pre-incubation of AVLE (10 µg/ml) for 15 min. The experiment was repeated in either the presence of NO synthase inhibitor, L-NAME (300 µM) or selective AT(1) receptor inhibitor, losartan (0.1 nM), or superoxide scavenger, tiron (1 mM) or a combination of L-NAME and AVLE. Superoxide production was measured by using enhanced-chemiluminescence assay. RESULTS: We have demonstrated that AVLE (10 µg/ml) effectively suppressed the Ang II-induced contraction (100 nM and 1 nM) of both endothelium-intact and -denuded rat aortic rings. In endothelium-intact rings, L-NAME, reversed AVLE-induced inhibition of Ang II-contraction. PE-induced contraction was significantly inhibited by AVLE in endothelium-intact rings, but not in endothelium-denuded rings. The inhibition by AVLE of PE-induced contraction was totally abolished in the presence of L-NAME. Ang II-induced SOA production concentration dependently with the optimal effect seen at 100 nM of Ang II, and AVLE (0.3, 1, 10 µg/ml) reduced this effect. SOA production in Ang II-stimulated rings was significantly higher than unstimulated control rings, while PE did not stimulate SOA production at all. SOA formation in the presence of Ang II was also inhibited in the presence of SOD (superoxide scavenger), DPI (NADPH inhibitor) and losartan (specific AT(1) receptor antagonist). CONCLUSION: These results collectively suggest that the ability of AVLE in inhibiting Ang II-induced contraction via its SOA scavenging properties and nitric oxide releasing effect may account for its usage as an antihypertensive treatment in traditional folk medicine.

Langerhans Cell Histiocytosis of Maxillary sinus.

Langerhan cell histiocytosis is a rare disease and usually occurs in paediatric age group. This disease may involve single or multiple organs system and has an unpredictable course of disease. The involvement of head and neck region are almost 90% of cases, however maxillary sinus involvement is very rare. We report a case of 2 year old boy presented with multi organ LCH (orbit, skull, sinus and liver). The mainstay treatment for this high risk multi organ LCH group is chemotherapy. Unfortunately, although with the advancement of treatment, their mortality rate is still high.

Selection of supported cobalt substrates in the presence of oxone for the oxidation of monuron.

The immobilization of cobalt ion on different media to catalyze oxone has been investigated. A probe herbicide, Monuron, was effectively degraded by using Co2+/oxone systems. For Co2+ supported on zeolite, 100% of Monuron could be removed within a 10 min reaction time. However, the recycling of the spent Co-zeolite catalyst using various posttreatments did not give a promising result. This is likely because the zeolite particles in solution have blocked and significantly attenuated the incident UV light from reducing Co3+ to Co2+. On the contrary, the use of cationic resin has minimized these problems. In the process of Co-resin/oxone/UV, faster Monuron decay could be achieved than that in the dark reaction. In the presence of UV, a significant drop of total organic carbon (TOC) was also observed in this approach suggesting an effective and clean process for Monuron mineralization.

The role of organic ligands in ferrous-induced photochemical degradation of 2,4-dichlorophenoxyacetic acid.

Recent studies have shown that hydrogen peroxide is generated in a ferrioxalate-induced photoreductive reaction, but information about the effect of organic ligands on the photochemical behaviour of ferrous species is limited. The degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by a ferrous-catalyzed oxidation in the presence of various ligands such as formate, citrate, malelate, oxalate, and ethylenediaminetetra-acetic acid (EDTA) was studied. The experiments were conducted under either dark or irradiated (350n m) conditions. Forty-two percent and 34% of 2,4-D were removed by the Fe(2+)/oxalate/UV and Fe(2+)/citrate/UV processes, respectively, after 30 min of reaction and oxidative intermediates were obtained in both cases. The presence of hydroxylated intermediates suggests that 2,4-D may be attacked by hydroxyl radicals, which are the products of the photo-Fenton-like reaction. As such, hydrogen peroxide was produced by the photolysis of ferrous oxalate or ferrous citrate, referred to hereafter as photogenerated H(2)O(2). As expected, the total removal percentage of 2,4-D jumped to 97% when 1mM of hydrogen peroxide (so-called spiked H(2)O(2)) was externally added to the reaction vessel to initiate the Fe(2+)/oxalate/UV process. Therefore, the treatment of 2,4-D by the Fe(2+)/oxalate/H(2)O(2)/UV system can be operated in two steps: the photolysis of ferrous oxalate first, followed by adding the spiked H(2)O(2) sometime after the commencement of the reaction. A two-phase model has been developed to describe this tandem ferrous-catalyzed photooxidation, which would help to achieve the mineralization of 2,4-D.

ROCs and SOCs: what's in a name?

There is currently a great deal of interest in the relative contributions of external and internally sequestered Ca(2+) in various physiological responses. However, this field is losing clarity due to inattentive use of terms. In particular, the terms "receptor-operated channels" and "store-operated channels" (ROCs and SOCs, respectively) are becoming ambiguous through over-use. In this paper, we will first consider basic principles of channel gating in order to set the stage for defining criteria which can be used to distinguish precisely between different channel-related functions. We will then focus on recurring examples of adventurous use of terminology, or of blurring of the distinctions between channel types, and propose solutions to this quandary.

Degradation of atrazine by modified stepwise-Fenton's processes.

The removal of atrazine (ATZ) by stepwise Fenton's processes (stepwise-FP) was studied and the system models were developed through the examination of reaction kinetics. The study compared the performance of the removal of ATZ by conventional FP with stepwise-FP, where the total dose of H(2)O(2) was split and inputted into the system at different times and/or quantities. The performance of stepwise-FP was found to be better than that of conventional FP. This was probably due to the minimization of the peak concentration of H(2)O(2) in the solution, which reduced the probability that valuable H(2)O(2) and hydroxyl radicals would be consumed in forming weaker radicals. The reaction kinetics of the decay of ATZ in stepwise-FP was found to be a two-stage process; and in each stage, fast decay followed by stagnant decay was observed. Two characterized constants (the initial decay rate and the oxidative capacity) were introduced and were found to be useful in quantifying the stepwise-FP. The models for predicting stepwise-FP with respect to different dosing times and/or asymmetrical doses were developed, and were found to be very useful for evaluating the system performance and/or for process design.

Acceleration and quenching of the photolysis of PCB in the presence of surfactant and humic materials.

The photodecay of a polychlorobiphenyl (PCB) congener, 2,3,4,5-tetrachlorobiphenyl (TeCB), in a surfactant-aided soil-washing process was investigated. The surfactant was found to be a useful hydrogen source in improving the TeCB photodecay via photoreduction process, while the light attenuation effect resulted from the nontarget compounds in the solution, and the impact of humic materials that co-extracted from the soil played important roles in the process of photolytic destruction of TeCB. A well-defined sediment, EPA-11, was used as the source of humic materials in examining the acceleration and quenching effects in the photolysis process. Experimental results indicated that the low dose of humic materials mainly acted as a supplementary hydrogen source to improve the photodegradation rate, while at a higher dose its amphoteric property of being a photochemical quencher become perceptible gradually, thus retarding the reaction. These effects were inspected and the dominant rate constants were quantified through the examination of possible sub-reactions in the assistant of proposed linear models in this study. The models under three different conditions at zero, low, and high humic levels associated with a light attenuation model were successfully developed to solve the dominant rate constants of the process. The good correlations between the experimental data and the models verify that the proposed reaction mechanisms of rate acceleration (resulting from the hydrogen source characteristics of the surfactant and humic material) and rate retardation (high levels of humic materials) coexist in the process.

Non-genomic action of estradiol and progesterone on cytosolic calcium concentrations in primary cultures of human granulosa-lutein cells.

BACKGROUND: The present study examined whether the sex steroids, estradiol and progesterone, could alter cytoplasmic calcium concentrations ([Ca(2+)](cyt)) in human granulosa-lutein cells. METHODS: Human granulosa cells were obtained at the time of oocyte retrieval for IVF and cultured for 3-7 days. Cells were loaded with Fura-2 AM and changes in [Ca(2+)](cyt) of single cells were studied using a dynamic digital Ca(2+) imaging system. RESULTS: Both estradiol and progesterone stimulated elevations of [Ca(2+)](cyt) in Ca(2+)-containing medium within seconds of exposure of the granulosa-lutein cells to the steroid, but only estradiol caused an increase in [Ca(2+)](cyt) in Ca(2+)-free medium. Both ICI-182780 and RU 486 stimulated [Ca(2+)](cyt) increases and inhibited the effects of estradiol and progesterone, respectively. Tamoxifen also induced transient increases in [Ca(2+)](cyt) concentrations but inhibited the effects of both estradiol and progesterone. The inhibitory effects of tamoxifen, ICI-182780 and RU 4486 on [Ca(2+)](cyt) responses to estradiol and progesterone could be reversed with higher concentrations of estradiol and progesterone, respectively. The [Ca(2+)](cyt) effects induced with tamoxifen could not be eliminated by prior treatment with RU 486 or ICI-182780. CONCLUSION: These results provide strong evidence that both estradiol and progesterone as well as the steroid antagonists, tamoxifen, RU 486 and ICI-182780, can act on human granulosa-lutein cells through a non-genomic mechanism.

A study of kinetic modelling and reaction pathway of 2,4-dichlorophenol transformation by photo-fenton-like oxidation.

The degradation of 2,4-dichlorophenol (2,4-DCP) by the photo-Fenton-like (Fe3+/H2O2/UVC) process under various reaction conditions was investigated. It was interesting to find that the reaction kinetics of 2,4-DCP in Fe3+/H2O2/UVC systems varied depending on the initial [Fe3+] concentration. A pseudo first-order kinetic and a non-conventional kinetic were discovered at low and higher [Fe3+] concentrations, respectively. A model was used to simulate the non-conventional kinetic process, where two character parameters (the initial decay rate and the final decay fraction) were found to be critical in determining the process. The two parameters successfully quantify the photo-Fenton-like oxidation under different concentrations of [Fe3+] and [H2O2] and the corresponding ratios of Fe(III)/H2O2. The reaction intermediates were identified by an LC/MS analysis and a reaction mechanism was proposed.

A study of the reaction mechanisms of the degradation of 2,4-dichlorophenoxyacetic acid by oxalate-mediated photooxidation.

The oxidation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by FeII/H2O2/UV (FHU) and ferrous-oxalate/H2O2/UV (FOHU) processes was investigated and compared. The initial decay rate and the overall removal percentage were used as the performance indexes. To extensively explore the associated processes, the intermediates and the end products were also examined and compared. The results showed that the degradation of 2,4-D by FHU is slower than that of FOHU. The involvement of ferrous-oxalate in the reaction can greatly improve the initial decay rate of 2,4-D because of the higher light sensitivity of the organometallic complexes. The total removal of 2,4-D and its corresponding intermediates was found to be strongly dependent on the initial hydrogen peroxide concentration; an excessively low initial [H2O2] will terminate the process due to the deficiency of hydroxyl radicals in the solution. All of the major primary intermediates (2,4-dichlorophenol, 2-chloro-4-hydroxyphenoxyacetic acid, 4-chloro-2-hydroxyphenoxyacetic acid, 5-hydroxy-2,4-dichlorophenoxyacetic acid and 6-hydroxy-2,4-dichlorophenoxyacetic acid) have been identified and confirmed by LC-MS. A reaction mechanism was proposed for FHU and FOHU and verified by the evidence presented in this study.

An unconventional approach to studying the reaction kinetics of the Fenton's oxidation of 2,4-dichlorophenoxyacetic acid.

The Fenton's oxidation kinetics of herbicide 2,4-D at various [Fe(II)] and [H(2)O(2)] combinations was investigated and modelled through an unconventional approach. The reaction kinetics of 2,4-D degradation demonstrated a two-stage pattern of decay, where a very fast reactive stage was followed by a retardation stage due to the depletion of oxidants and to the competitive side-reactions of the intermediates (including 2,4-dichlorophenol, chlorohydroquinone and 2,6-dichlororesorcinol). A model characterized by two newly established constants, the initial decay rate and the maximum oxidative capacity, was proposed and proven capable of describing the two-stage process, which cannot easily be described by conventional first- or second-order kinetics approaches.

The system design of UV-assisted catalytic oxidation process--degradation of 2,4-D.

Unlike the conventional first- or second-order model, a novel approach to design for the removal of 2,4-dichlorophenoxy (2,4-D) by the UV-catalytic oxidation process (UVCOP) was investigated. Two distinctive parameters, initial decay rate and maximum oxidative capacity, were characterized. By using these parameters, the performance of the degradation of 2,4-D by UVCOP regarding to the reagent dosages could be successfully predicted. Low concentrations of ferrous ion was found to be a rate-limiting factor for the process while the dosage of hydrogen peroxide was concluded as a dominant species in determining the maximum oxidation capacities. This information can be used to optimize the treatment process and achieve the expected performance target; an "optimal-dose model" was developed accordingly. The model is an intelligent and useful tool to evaluate the optimal doses of hydrogen peroxide with the minimum dose of ferrous ion, which leads to a better design of the treatment process.

Modeling the ozonation of herbicide 2,4-D through a kinetic approach.

A quantitative estimation of the ozonation of a herbicide 2,4-D solution through a kinetic approach was studied and modelled. The ozonation of 2,4-D was found to follow a pseudo-first-order kinetic and the degradation rates depended on the initial pH and on the ozone concentration. A model was proposed to quantitatively predict the pseudo-first-order rate constants of the decay of 2,4-D under different ozone concentrations and initial pH levels based on some useful and practical assumptions. The proposed model was able to successfully describe the reaction with insignificant errors; therefore another practical equation was proposed to size the contact tower for 2,4-D ozonation by ozone concentration (overdosed) and initial pH level.

Dichlorodiphenylchloroethylene elevates cytosolic calcium concentrations and oscillations in primary cultures of human granulosa-lutein cells.

1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), a metabolite of DDT (1,1-dichlorodiphenyltrichloroethane), is a persistent hormonally active environmental toxicant that has been found in human serum and follicular fluid. The objective of this study was to determine whether DDE can alter free calcium ion concentrations in the cytosol ([Ca(2+)](cyt)) of human granulosa cells. Changes in [Ca(2+)](cyt) in single cells loaded with Fura-2 were studied using a dynamic digital Ca(2+) imaging system. At a concentration of 100 ng/ml, DDE stimulated small elevations of [Ca(2+)](cyt) accompanied by Ca(2+) oscillations. At 1 microg DDE/ml, there was a biphasic Ca(2+) response with marked elevations of [Ca(2+)](cyt) over time. In Ca(2+)-free medium, cells showed an initial small elevation of [Ca(2+)](cyt), which was magnified after addition of Ca(2+) to the medium. Washing the cells after DDE treatment failed to remove the elevated [Ca(2+)](cyt) and oscillations, both of which were eliminated by addition of EGTA. ATP also induced [Ca(2+)](cyt) elevations and oscillations, and these effects were potentiated when DDE was added. FSH induced transient [Ca(2+)](cyt) elevations, whereas hCG caused a prolonged elevation and marked oscillations in [Ca(2+)](cyt). These results suggest that DDE at concentrations normally found in human tissues induces elevations in [Ca(2+)](cyt) in granulosa-lutein cells. Our data therefore highlight a novel mechanism through which DDE can alter endocrine homeostasis and possibly act as an endocrine toxicant.

Photodegradation of 2,4-dichlorophenoxyacetic acid in various iron-mediated oxidation systems.

The oxidation of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by different iron-mediated processes, with or without the presence of ultraviolet (at 253.7 nm) and oxalate, was investigated and compared. The initial decay rate and the overall removal percentage were used as the performance indexes. To extensively explore the associated processes, the following combinations or blank systems were investigated: UV radiation only, Fe(2+)/H(2)O(2), Fe(2+)/H(2)O(2)/UV, ferrous oxalate/H(2)O(2), ferrous oxalate/H(2)O(2)/UV, Fe(3+)/H(2)O(2), Fe(3+)/H(2)O(2)/UV, ferrioxalate/H(2)O(2), and ferrioxalate/H(2)O(2)/UV. This study showed that the degradation of 2,4-D by sole UV or dark processes (without UV) is generally slow, except by the conventional Fenton's process (Fe(2+)/H(2)O(2)). However, these slow reactions can be accelerated by exposure to UV irradiation, which can increase the initial 2,4-D decay rate from ten to more than one hundred times. Furthermore, if the reaction is initiated by ferrous oxalate or ferrioxalate instead of Fe(2+) or Fe(3+) ions, the rates can be further improved, because of the higher light sensitivity of the organometallic complexes. These reactions were also found sensitive to the initial hydrogen peroxide concentration. The competition of hydroxyl free radicals by the primary intermediate, 2,4-dichlorophenol, was also observed.

Remediation of contaminated soil by a solvent/surfactant system.

This study investigates a new approach using a solvent/surfactant-aided soil-washing process to improve the performance of conventional surfactant-aided soil remediation. Three surfactants (Brij 35, Tween 80, and SDS) and three organic solvents (acetone, triethylamine, and squalane) were used to evaluate the desorption performances of 4,4'-dichlorobiphenyl (DCB) out of three soils with different sorption characteristics. The performance improvement is likely due to better dissolution of the hydrophobic contaminants from the soil assisted by the solvent, and the formation of solvent-incorporated surfactant micelles, which increases both the size (i.e. capacity) and affinity of micelles for more effective contaminant extraction. The foc of soils were found to be important in determining the performance of a solvent/surfactant-aided soil-washing process. Judging from the experimental data and as verified by the two constants in the proposed soil-washing model, as the organic solvent is coexisting with the surfactant micelles, both the marginal soil-washing performance (right after the use of a very small amount of solvent compared to that of none) and the final soil-washing capacity are increased compared to those of a pure surfactant-aided washing process.

Reactor design and kinetics study of 4,4'-dichlorobiphenyl photodecay in surfactant solution by using a photosensitizer and hydrogen source.

The system design based on the photodegradation kinetics of 4,4'-dichlorobiphenyl (4,4'-DCB) in surfactant solution with the aid of solvents (acetone and/or squalane) has been studied. Organic solvents acetone and squalane were added as a photosensitizer and a hydrogen source, respectively, to achieve better photolysis performance. The quantum yield of 4,4'-DCB photodecay in Tween 80 micellar solution in the presence of added acetone was increased from 0.032 to 0.043 at its optimal condition. Acetone was shown to be an effective photosensitizer at low concentration, but an overdose would quench the reaction. Furthermore, the addition of squalane could further promote the photodechlorination of 4,4'-DCB in the Tween 80/acetone solutions for an additional 59% of rate improvement. However, an overdose of either solvent was found to cause UV light attenuation and to reduce the observed quantum yield. This effect has been justified and quantified in this study by a proposed light attenuation model, which has also been incorporated into the kinetic equation so that the resulted formula can be used to design the UV reactors for water and wastewater treatment works.

Effect of calcium on the vascular contraction induced by cobra venom cardiotoxin.

1. The cytotoxic effects of cardiotoxin (CTX) purified from Cobra venom were tested in endothelium-denuded rat aortic ring preparations in tissue organ baths and the effect of extracellular Ca2+ on the cytotoxic effect of CTX was investigated using a digital dynamic calcium imaging technique. 2. At 10 micromol/L, CTX induced a slowly developing and sustained contraction that amounted to approximately 50% of the maximal contraction induced by 80 mmol/L KCl. At high concentrations (> 15 micromol/L), CTX caused irreversible damage to the smooth muscle contractile function. However, washout of CTX at its peak contraction did not affect the subsequent contraction to either KCl or phenylephrine. 3. Contraction induced by CTX was dependent on the Ca2+ concentration in the external solution. A maximal contractile response to CTX was obtained in medium containing 1-2.5 mmol/L Ca2+. This contractile response induced by CTX decreased with higher Ca2+ concentrations and was completely diminished when 7 mmol/L Ca2+, 3 mmol/L Ni2+ or 30 micromol/L tetrandrine (a non-selective calcium channel blocker) was present in the external solution before addition of CTX to the bath. 4. The above observations were supported by the calcium imaging work performed with cultured aortic smooth muscle cells from Wistar-Kyoto rats, in which CTX was shown to induce the elevation of cytosolic Ca2+ in the presence, but not in the absence, of 2.5 mmol/L extracellular Ca2+. Increasing the extracellular Ca2+ concentration to 7 mmol/L, the addition of 3 mmol/L Ni2+ or inclusion of 30 micro mol/L tetrandrine inhibited the elevation of cytosolic Ca2+ induced by CTX. 5. These results suggest that: (i) a CTX-sensitive internal calcium store does not exist in rat aortic smooth muscle; (ii) the contractile effect CTX is associated with a Ca2+ influx process; and (iii) CTX interacts extracellularly with the plasma membrane at the level of the calcium channels, as well as anionic sites to which Ca2+ and other inorganic cations bind.

Evidence for the existence of a constitutive nitric oxide synthase in vascular smooth muscle.

1. We have identified a neuronal nitric oxide synthase (NOS)-like constitutive form of NOS in vascular smooth muscle (VSM) using a functional contractility approach as well as immunohistochemical methods. 2. N(G)-Nitro-L-arginine methyl ester, N(G)-monomethyl-L- arginine and N(G)-nitro-L-arginine (L-NOARG), the competitive inhibitors of NOS, inhibited Mg(2+)-induced relaxation of de-endothelialized rat aorta precontracted with phenylephrine (PE). This Mg(2+) relaxation of VSM was not affected by inhibitors of inducible NOS. 3. Electrical field stimulation (EFS; 30-70 Hz) caused relaxation of rat aorta in the presence of tetrodotoxin (therefore not a neurogenic effect) and this EFS relaxation was effectively inhibited by L-NOARG, oxyhemoglobin and methylene blue. 4. Immunohistochemical studies of dog saphenous vein using antibodies raised against neuronal NOS indicated prominent staining along the plasmalemma in a punctate pattern similar to the distribution of antibodies against caveolin-1, a major constituent of the plasmalemmal caveolae. 5. We propose that a constitutive NOS of non-endothelial, non-neuronal origin is present in a special caveolae domain of VSM cell membranes and could be activated by an ionic mechanism yet to be characterized.

The direct and indirect photolysis of 4,4'-dichlorobiphenyl in various surfactant/solvent-aided systems.

Surfactant and organic solvents have individually been shown useful in assisting the solubilization of hydrophobic organics out of contaminated soil and promoting UV-induced photodecay at a succeeding treatment process. A newly proposed process is to use the mixtures of surfactant and solvents together in achieving better performance. This study was to explore some basic variables and conditions that may be useful in optimizing the performance of surfactant/solvent-aided UV systems through the selection of surfactant micelles, the adjustment of the reaction pH levels, and the addition of photosensitizer and hydrogen sources. A PCB monomer 4,4'-dichlorobiphenyl (DCB) was used as the target compound for this study; about 1.3 to 2.3 times greater DCB photodecay rate enhancements were observed by using surfactant/acetone or surfactant/triethylamine (TEA) combinations at their optimal conditions. Overdose of these additives (acetone and TEA) will result in retardation of the reactions. However, the use of surfactant with a multisolvents system (surfactant/acetone/TEA) shows an add-on effect in amplifying the overall decay rate for more than 12%, suggesting that a more complicated mechanism is involved than the simple parallel-reaction assumption.