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Release of algesic substances in human experimental muscle pain.

OBJECTIVE: We employed the 'delayed onset of muscle soreness' (DOMS) and the 'hypertonic saline' muscle pain models in combination with muscle microdialysis to evaluate the role of potentially algesic substances (lactate, glutamate, prostaglandin E2 (PGE2), nitric oxide (NO) and substance P (SP)) in the development of human muscle pain. METHODS: DOMS was induced by 2 sets of 50 concentric/eccentric contractions of the calf muscles 24 h before the start of microdialysis. During microdialysis pain was stimulated through calf muscle contractions (dorsal and plantar flexions of the foot). Hypertonic saline was injected into the biceps muscle (5 x 200 microl 5.8% NaCl, 2 min interval) during dialysis. The calf (no treatment) and biceps (normal saline) of the other side was used as control. RESULTS: Both models reliably induced muscle pain with similar intensities as assessed by visual analog scale. The DOMS exercise caused an increase of lactate in serum and the calf muscles of the DOMS leg. In addition, glutamate, PGE2 and substance P dialysate concentrations increased following contraction-induced pain stimulation (peak concentrations 125 +/- 20 microM, 239 +/- 45 pg/ml and 60 +/- 11 pg/ml for glutamate, PGE2 and SP, respectively). This increase did not occur in the control leg (peak concentrations 97 +/- 12 microM, 114 +/- 26 pg/ml and 46 +/- 9 pg/ml for glutamate, PGE2 and SP, respectively). Concentrations of nitric oxide were lower in the DOMS than control leg, particularly during the first 4h of microdialysis. Injection of hypertonic saline into the biceps muscle caused a significant increase of dialysate glutamate concentrations (peak 50 +/- 3 microM) whereas glutamate remained constant after injection of normal saline (mean 26 +/- 1 microM). Injection of hypertonic saline had no effect on lactate, PGE2 or NO levels. CONCLUSION: Our data support the notion that an inflammatory reaction may be involved in muscle soreness following eccentric exercise, whereas the injection of hypertonic saline into the muscle probably directly stimulates muscle nociceptors and causes glutamate release.

Adult↗

Renal effects of exogenous dopamine: modulation by renal nerves and dopamine receptor antagonists.

The modulation of the renal response to exogenous dopamine by renal denervation (DNX) and dopamine receptor antagonists was investigated in thiopental-anesthetized Sprague-Dawley rats. Experiments were performed after reaching stable systemic hemodynamics and urinary flow rate. These conditions were obtained with an infusion rate of approximately 1.2% of body weight per hour. In the vehicle group (VHC) i.v. infusion of dopamine (1, 3 and 9 microg kg(-1) min(-1) significantly increased glomerular filtration rate (GFR), assessed by renal clearance of [3H]inulin, by 14+/-1.5, 16+/-1.6 and 31+/-2.6%, respectively. Infusion of 1 and 3 microg kg(-1) min(-1) dopamine did not change systemic hemodynamics while the highest dose elevated heart rate, potentially contributing to the GFR increase. The specific D1 receptor antagonist SCH 23390 (10 microg kg(-l) min(-1) i.v.) did not affect the GFR response to dopamine infusion. In contrast, domperidone (DOM; 8 microg kg(-1) min(-1) i.v.), a specific, peripherally acting D2 antagonist, attenuated the glomerular hyperfiltration induced by the three doses of dopamine to 11+/-1.7, 13+/-2.2 and 16+/-2.6%, respectively. DNX diminished the GFR response to dopamine infusion to almost the same extent (11+/-2.8, 10+/-2.2 and 17+/-2.6%, respectively) as did DOM. When DNX animals were treated with DOM, the GFR responses to dopamine were further attenuated to non-significant increases. These additive effects of DOM and DNX suggest that two different mechanisms are involved. Both DNX and SCH 23390 decreased sodium excretion at baseline whereas DOM enhanced it. Under the present experimental condition, neither D1 nor D2 receptor blockade affected the natriuretic and diuretic response to dopamine. Whereas D1 receptors do not appear to be involved, both D2 receptors and renal nerves play a role in the renal hemodynamic response to dopamine, indicating involvement of both pre- and postsynaptical dopamine receptors.

Animals↗

Simultaneous determination of domperidone and cinnarizine in a binary mixture using derivative spectrophotometry, partial least squares and principle component regression calibration.

This work is concerned with the simultaneous determination of domperidone maleate (DOM) and cinnarizine (CINN) in a binary mixture form, without previous separation, by two different techniques. The first method is the application of derivative spectrophotometry where the linearity range and percentage recoveries for DOM and CINN were 2.5-30 micro g mL(-1), 5-25 micro g mL(-1) and 100.06+/-1.157, 99.93+/-1.377, respectively. The second method depends on the application of partial least squares (PLS) and principle component regression (PCR) models. A training set consisting of 10 mixtures containing 5-20 micro g mL(-1) for each component was used for the construction of the PCR and PLS models. These models were used after their validation for the prediction of the concentration of DOM and CINN in their mixtures. The proposed procedures were successfully applied for the simultaneous determination of both drugs in laboratory prepared mixtures and in commercial tablet preparations. The validity of the proposed methods was assessed by applying the standard addition technique where the percentage recovery of the added standard was found to be 99.98+/-0.297 and 99.84+/-0.700 for DOM and CINN, respectively, using the derivative spectrophotometric method and 100.29+/-0.398 and 100.11+/-0.363 for DOM and CINN, respectively, using the PLS and PCR methods. The proposed procedures are rapid, simple, require no preliminary separation steps and can be used for routine analysis of both drugs in quality control laboratories.

Calibration↗

Detection of domoic acid in rat serum and brain by direct competitive enzyme-linked immunosorbent assay (cELISA).

In 1987 a large-scale incident of human poisoning in Canada was traced to commercial mussels contaminated with domoic acid (DOM). Since then, routine screening of shellfish domoic acid content has been carried out using a variety of assays, with liquid chromatography using ultraviolet absorbance detection (LC-UV) or mass spectrometric detection (LC-MS) being the currently accepted standard methodologies. Recently, a highly specific competitive enzyme-linked immunosorbent assay (cELISA) has been developed for the detection and analysis of DOM in commercial shellfish, but its accuracy relative to LC methods has not been independently verified in mammalian tissues. In this study we demonstrate that measurement of rat serum DOM concentration by cELISA gives a good correlation (r2 = 0.993) across a broad range of concentrations when compared to LC-MS analysis, with only a small (15%) overestimation of sample DOM content. In addition, we have developed an extraction method for analysis of DOM in rat brain by cELISA which yields complete recovery across a range of sample dilutions.

Animals↗

The response of Vibrio- and Rhodobacter-related populations of the NW Mediterranean Sea to additions of dissolved organic matter, phages, or dilution.

We investigated the growth response of the heterotrophic prokaryotic community focusing on Vibrio- and Rhodobacter-related populations (SRF3) to variation in the availability of dissolved organic matter (DOM), population density-dependent effects, and prokaryotic virus (phage) infection in coastal and offshore waters of the NW Mediterranean Sea. We tested the response of the prokaryotic community to three different DOM fractions prepared by ultrafiltration. One of the DOM fractions contained phages (<0.2 m), a second was virus-free (<100 kDa), and a third contained only low molecular weight (<1 kDa). The proportion of Vibrio and SRF3 populations as determined by fluorescent in situ hybridization in the community ranged from <1 to 6.2% and from 3.2 to 6.3%, respectively. Based on changes in cell numbers, growth rates ranged from 2.1 to 3.1 day(-1) for Vibrio and from 0.8 to 1.2 day(-1) for SRF3. Growth rates of Vibrio were similar or higher than those of the total prokaryotic community, whereas the ability of Vibrio to use high molecular weight (HMW) DOM and the responses to additions of phage-rich material were lower. Growth rates of SRF3 were lower than that of the community. Susceptibility to infection of SRF3 was sometimes lower than in the community, whereas the growth stimulation of HMW DOM was similar or lower. Reducing the cell concentrations of the prokaryotic community by dilution stimulated the overall growth of the community, including that of its constituent Vibrio and SRF3 populations, but the effect was smaller on the SRF3 and greater on Vibrio populations than for the total community. Comparisons with the community also revealed that life strategy traits of bacterial populations differed between coastal and offshore waters. Overall, our data suggest that Vibrio is an r-strategist or opportunistic population in the NW Mediterranean Sea, whereas SRF3 is a K-strategist or equilibrium population.

Bacteriophages↗

A proteomic fingerprint of dissolved organic carbon and of soil particles.

Mass spectrometry-based proteomics was applied to analyze proteins isolated from dissolved organic matter (DOM). The focal question was to identify the type and biological origin of proteins in DOM, and to describe diversity of protein origin at the level of higher taxonomic units, as well as to detect extracellular enzymes possibly important in the carbon cycle. Identified proteins were classified according to their phylogenetic origin and metabolic function using the National Center for Biotechnology Information (NCBI) protein and taxonomy database. Seventy-eight percent of the proteins in DOM from the lake but less than 50% in forest soil DOM originated from bacteria. In a deciduous forest, the number of identified proteins decreased from 75 to 28 with increasing soil depth and decreasing total soil organic carbon content. The number of identified proteins and taxonomic groups was 50% higher in winter than in summer. In spruce forest, number of proteins and taxonomic groups decreased by 50% on a plot where trees had been girdled a year before and carbohydrate transport to roots was terminated. After girdling, proteins from four taxonomic groups remained as compared to nine taxonomic groups in healthy forest. Enzymes involved in degradation of organic matter were not identified in free soil DOM. However, cellulases and laccases were found among proteins extracted from soil particles, indicating that degradation of soil organic matter takes place in biofilms on particle surfaces. These results demonstrate a novel application of proteomics to obtain a "proteomic fingerprint" of presence and activity of organisms in an ecosystem.

Carbon↗

Effects of [D-Arg6, Trp7, Leu8, Pro9NEt]-luteinizing hormone-releasing hormone (sGnRH-A) and [D-Ala6, Pro9NEt]-luteinizing hormone-releasing hormone (LHRH-A), in combination with pimozide or domperidone, on gonadotropin release and ovulation in the Chinese loach and common carp.

The effects of LHRH-A and sGnRH-A alone and in combination with the dopamine receptor antagonists pimozide (PIM) and domperidone (DOM) on stimulation of gonadotropin (GtH) secretion and ovulation in Chinese loach (Paramisgurnus dabryanus) and common carp (Cyprinus carpio) were studied. When tested in the absence of a dopamine receptor antagonist, sGnRH-A was about 10-fold more potent than LHRH-A in stimulating GtH secretion in loach, whereas these peptides were of similar effectiveness in common carp. Both peptides were effective alone in inducing ovulation in loach, but were ineffective in common carp. PIM and DOM stimulate a small but significant increase in serum GtH, and greatly potentiate the effects of LHRH-A and sGnRH-A on GtH secretion and ovulation in both species. DOM was of equal or somewhat greater potency than PIM in potentiating the action of releasing hormone agonists in loach; however, DOM had markedly greater effectiveness in common carp. sGnRH-A in the presence of DOM was more effective than LHRH-A in stimulating GtH secretion and ovulation in common carp. The present studies suggest that there are marked differences in the relative contribution of GnRH and dopamine in the control of GtH secretion in loach and common carp, and indicate in particular that the more intense dopaminergic inhibitory control of GtH release in common carp modifies the responsiveness of the pituitary to GnRH peptides.

Animals↗

Evaluation of domperidone as a modifier of gamma-radiation-induced emesis.

The D2 antidopaminergic drug domperidone was evaluated, singly and in combination with synthetic adrenocorticoid and an H2 antihistamine, for its ability to reduce the acute emetic effects of 60Co whole-body radiation. Random-source adult male dogs were fasted 12 hr, fed a standard meal, injected 44 min later, and irradiated 47 min after that. Four groups of dogs were irradiated after drug injections as follows: saline (Con), domperidone (Dom), cimetidine + thiethylperazine (Cim + Thi), and dexamethasone + domperidone + cimetidine (Dex + Dom + Cim). Drug quantities given the dogs represented 10 mg Dom, 10 mg Thi, 20 mg Dex, and 300 mg Cim for an average human (70 kg, 1.8 m2). Subjects were exposed on an up-down schedule to determine the radiation necessary to produce vomiting in 50% (ED50) of each group. Emesis onset and offset times and number of episodes were recorded. The Dom group had more emetic episodes than any other. The Dex + Dom + Cim combination significantly raised the emetic threshold while maintaining episodes at a low incidence.

Animals↗

Interactions between mercury and dissolved organic matter--a review.

Dissolved organic matter (DOM) interacts very strongly with mercury, affecting its speciation, solubility, mobility, and toxicity in the aquatic environment. Strong binding of mercury by DOM is attributed to coordination of mercury at reduced sulfur sites within the organic matter, which are present at concentrations much higher than mercury concentrations found in most natural waters. The ability of organic matter to enhance the dissolution and inhibit the precipitation of mercuric sulfide, a highly insoluble solid, suggests that DOM competes with sulfide for mercury binding. This is confirmed by very high conditional stability constants for mercury-organic sulfur (RSHg+) complexes (10(25)-10(32)) recently reported in literature. DOM appears to play a key role in the photochemical reduction of ionic mercury to elemental mercury and subsequent reoxidation of elemental mercury to ionic mercury, thus affecting volatilization loss and bioavailability of mercury to organisms. DOM affects the production and bioaccumulation of methylmercury, the most bioaccumulative mercury species in fish.

Ligands↗

Distinguishing sources of groundwater nitrate by 1H NMR of dissolved organic matter.

Dissolved organic matter (DOM) originating from a certain source usually carries characteristic marks in its molecular structures that can be recognized by spectroscopic analysis. Sources of water-borne contaminants, such as nitrate, can be identified by recognition of the characteristics of DOM entrained in the water. In this study, DOM in groundwaters sampled from a dairy/crop production area (Chino Basin, CA) was analyzed by 1H nuclear magnetic resonance (1H NMR). Results showed that DOM derived from natural soil organic matter has a characteristic resonance at a chemical shift region of 4.0-4.3 ppm, while DOM derived from dairy wastes has a characteristic resonance at a lower chemical shift region of 3.2-3.6 ppm. These signature resonances were then used to distinguish the origins of nitrate in the groundwater. It was found that disposal of dairy wastes on croplands is the primary source of nitrate contamination in groundwater underlying the Chino Basin dairy area.

California↗

Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching.

Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils.

2,4-Dichlorophenoxyacetic Acid↗

Spectrofluorometric properties of dissolved organic matter from Central and Southern Ontario streams and the influence of iron and irradiation.

Fluorescence measurements were used to compare characteristics of dissolved organic matter (DOM) from distinctly different origins: boreal, agricultural and urban streams as well as a storm runoff pond and the outlet of a tertiary wastewater treatment plant. The primary goal was to determine if differences among stream types could be detected using DOM fluorescence in lieu of isolated fulvic acids (FA). Differences in peak excitation and peak emission wavelengths, fluorescence integrated over the 3-D matrix volume integrated fluorescence (VIF), and in a fluorescence index (FI) were examined. In general, peak fluorescence excitation and emission wavelengths as well as FI best distinguished DOM from the various origins. Results suggested that DOM from the boreal streams was of a higher molecular weight and more complex than that of agricultural and urban streams. The effects of irradiation as well as Fe on fluorescence of natural stream waters were also investigated, both of which decreased the ability of optical properties to distinguish DOM source.

Environmental Monitoring↗

Hydrogeochemical controls on the organic matter and bacterial ecology of a small freshwater wetland in the New Jersey Pine Barrens.

This study investigated the effects of variable ground-water/surface-water exchange and photoinduced processes on longitudinal patterns in dissolved organic matter (DOM) and bacterial communities in a small first-order stream in the New Jersey Pine Barrens. DOM concentration, along with DOM weight average molecular weight (Mw) and absorptivity (epsilon280, an estimator of aromaticity), and bacterial cell counts all decreased from the stream and hyporheic zone into the shallow aquifer in a ground-water recharge zone. Further downstream, influx of ground water into the stream resulted in a lower Mw DOM pool and was accompanied by decreased cell counts. The observed effect of this ground-water discharge on bacterial numbers may be direct, if discharge temporarily dilutes cell counts, or indirect, if changes in DOM concentration and properties control the bacterial community. In either case, this study suggested the importance of considering ground-water-surface-water exchange in studies of longitudinal changes in the bacterial communities of streams.

Ecosystem↗

Estimation of the hydrophobic fraction of dissolved organic matter in water samples using UV photometry.

In this study, we tested a simple and rapid method for the estimation of carbon in the hydrophobic fraction of dissolved organic matter (DOM) of different origin (spruce, pine, and beech litter) in soil water. The method is based on the fact that the hydrophobic fraction of DOM contains almost entirely the aromatic moieties of DOM. Thus, it showed a clearly distinct light absorption at 260 nm compared to the hydrophilic fraction. This light absorption was directly proportional to the concentration of the hydrophobic fraction. Moreover, it was independent of the concentration of the hydrophilic fraction. We compared the concentrations of hydrophobic DOM estimated by the UV method with those of the conventional fractionation using chromatographic columns of XAD-8 macroporous resin and found an excellent agreement between the two methods for both solutions from laboratory sorption experiments and field samples of forest floor leachates and subsoil porewaters. In addition, the absorption at 260 nm of hydrophobic DOM proved to be independent of pH values ranging from 2.0 to 6.5. Compared to the conventional chromatographic fractionation, the method using the UV absorption at 260 nm is less time consuming, needs a much smaller sample volume, and showed a better reproducibility. However, its use is restricted to water samples of low nitrate (< 25 mg L(-1)) and Fe (< 5 mg L(-1)) concentrations and, probably, with the hydrophobic fraction dominated by aromatic compounds deriving from degradation of lignin.

Carbon↗

Molecular characterization of dissolved organic matter in freshwater wetlands of the Florida Everglades.

In this study, the molecular composition of dissolved organic matter (DOM), collected from wetlands of the Southern Everglades, was examined using a variety of analytical techniques in order to characterize its sources and transformation in the environment. The methods applied for the characterization of DOM included fluorescence spectroscopy, solid state 13C CPMAS NMR spectroscopy, and pyrolysis-GC/MS. The relative abundance of protein-like components and carbohydrates increased from the canal site to more remote freshwater marsh sites suggesting that significant amounts of non-humic DOM are autochthonously produced within the freshwater marshes, and are not exclusively introduced through canal inputs. Such in situ DOM production is important when considering how DOM from canals is processed and transported to downstream estuaries of Florida Bay.

Ecosystem↗

Interactions of silver with wastewater constituents.

The interactions of silver ion with wastewater constituents including chloride, sludge particulates, and dissolved organic matter (DOM) were investigated using fresh and processed sludge samples from various municipal wastewater treatment plants. Fresh sludge samples were used to examine the silver removal characteristics in the presence of chloride. Processed sludge samples that were subjected to a deionized-water washing procedure to remove the chloride ion were used to examine the interactions among Ag(I), sludge solids, and DOM. Results showed that, under field conditions, most of the silver can be removed through precipitation with chloride and adsorption by sludge particulates. Results obtained using washed sludge samples showed that Ag(I) adsorption by sludge particulates increases with the increase of pH in the acidic pH range, but decreases with the increase of pH in the alkaline pH range. Since the DOM concentration increases significantly with the increase of pH in the alkaline pH region, it can be concluded that the formation of Ag(I)-DOM complexes reduces the Ag(I) adsorption by sludge. Fitting of the Langmuir isotherm to the adsorption data indicated that adsorption constants have a slight increase with the increase of pH in the acidic pH range, but decrease significantly with the increase of pH in the alkaline pH range. The decrease of the Ag(I) adsorption constants in the alkaline pH range can be attributed to the formation of Ag(I)-DOM complexes which weaken the Ag(I) binding strength by sludge surface sites. The fitted isotherms also showed that the Ag(I) adsorption capacity increases with the increase of pH in the entire pH range.

Adsorption↗

Characterisation of humic materials of different origin: a multivariate approach for quantifying the latent properties of dissolved organic matter.

The inherent chemical properties of eight different dissolved organic matters (DOMs) originating from soil, surface and groundwater have been analysed. The samples consist of isolated fulvic acids (FA), humic acids (HA), and humic substances (HS), i.e. natural mixtures containing a humic and a fulvic fraction. The humic substances have been characterised by elemental analysis, size exclusion chromatography, E2/E3 and E4/E6 UV absorption ratios, and liquid-state 13C-NMR spectroscopy. The information contents of the different analytical methods have been investigated by pattern recognition, i.e. cluster analysis and principal component analysis (PCA). A comparative study of the information contents of DOM descriptors derived from different analytical methods is presented. Through extraction of information content of the individual analytical methods the inherent properties of DOM are quantified. Pattern recognition revealed significant quantitative differences in the inherent properties of DOM of different origin and type. PCA based on the NMR descriptors showed highest explained variance. However, all models showed low robustness due to the limited number of samples. The supervised pattern recognition, i.e. PCA, indicates a classification of DOMs into groups of similar properties by an increase in the number of samples. Furthermore that the number of groups may be higher and more continuously distributed than the conventional classification into fulvic acids, humic acids or humic substances.

Chromatography, Gel↗

Mobilization of heavy metals and arsenic in polluted wetland soils and its dependence on dissolved organic matter.

The wetland soils of the Mulde river in the industrial district of Bitterfeld-Wolfen (Germany) are highly contaminated with heavy metals and arsenic. We studied the mobility of accumulated heavy metals and arsenic and the influence of dissolved organic matter (DOM) on element mobility. Undisturbed soil cores were taken from five different sites to represent a wide range of heavy-metal contamination, soil properties and dissolved organic carbon (DOC) concentrations. The acid-soluble concentrations (mostly equal to the total content) were up to 1100 mg kg-1 for Zn, 800 mg kg-1 for Cr, 364 mg kg-1 for Cu, 265 mg kg-1 for As and 37 mg kg-1 for Hg, depending on the sampling site. Percolation experiments using small lysimeters with undisturbed topsoil cores illustrated a considerable mobilization of Zn, Cd, Cu, Cr and Hg, depending on soil properties. Up to 80 micrograms l-1 Cd, 8 mg 1-1 Zn, 130 micrograms l-1 Cr, 160 micrograms l-1 Cu and 7 micrograms l-1 Hg were detected in the soil percolates. Arsenic mobilization was low. The concentration of Cr, Hg, Cu and As in the soil percolates was positively correlated with DOM. Besides the element content (mobile or acid-soluble), soil pH and soil characteristics describing the soil potential for heavy-metal adsorption (clay, oxides, cation exchange capacity), the DOC concentration in the soil solution should be known to access the potential mobilization of Hg, Cr, Cu and As. In contrast, Cd and Zn mobilization depends on soil pH and mobile element content, but not on DOM. Additional studies on two soil profiles (down to 1.5 m) confirmed the translocation of heavy metals from the highly contaminated topsoil into deeper soil horizons and into the groundwater and the influence of DOM as revealed with the percolation experiment. Our results also showed that DOM is of minor importance on the mobilization of heavy metals in soils with a low soil pH (< 4.5).

Adsorption↗