Effect Of Chemical Form Research Articles

Effect of chemical form, heating, and oxidation products of linoleic acid on rumen bacterial population and activities of biohydrogenating enzymes

Heating polyunsaturated fatty acids (PUFA) produces oxidation products, such as hydroperoxides, aldehydes, and oxypolymers, which could be responsible at least in part for modification of PUFA rumen biohydrogenation (BH). Three in vitro experiments were conducted to investigate the effects of linoleic acid (cis-9,cis-12-C18:2) oxidation products on BH. In the first experiment, we studied the effects of free linoleic acid (FLA), heated FLA (HFLA, at 150°C for 6h), triacylglycerols of linoleic acid (TGLA), heated TGLA (HTGLA, at 150°C for 6h), 13-hydroperoxide (13HPOD), trans-2-decenal (T2D), and hexanal (HEX) on BH in vitro after 6 and 24h of incubation. In the second experiment, aldehydes differing in chain length and degree of unsaturation [pentanal, HEX, heptanal, nonanal, T2D, trans-2,trans-4-decadienal (T2T4D)] were incubated in vitro for 5h in rumen fluid. In the third experiment, 9-hydroperoxide (9HPOD), 13HPOD, HEX, or T2T4D were incubated for 1h in rumen fluid inactivated with chloramphenicol to investigate their effects on enzyme activity. In experiment 1, heat treatment of TGLA generated TGLA oxypolymers, did not affect cis-9,cis-12-C18:2 disappearance, but did decrease BH intermediates, especially trans-11 isomers. Heating FLA decreased cis-9,cis-12-C18:2 disappearance and cis-9,trans-11-CLA and trans-11-C18:1 production. Treatment with HEX and T2D did not affect cis-9,cis-12-C18:2 disappearance and barely affected production of BH intermediates. The bacterial community was affected by 13HPOD compared with FLA and HFLA, in parallel with an increase in trans-10 isomer production after a 6-h incubation. After 24h of incubation, 13HPOD decreased trans-11 isomer production, but to a lesser extent than HFLA. In experiment 2, some weak but significant effects were observed on BH, unrelated to chain length or degree of unsaturation of aldehydes; the bacterial community was not affected. In experiment 3, 9HPOD inhibited Δ9-isomerization, and both 9HPOD and 13HPOD inhibited Δ12-isomerization. We concluded that oxypolymers did not affect cis-9,cis-12-C18:2 disappearance. Heating both esterified and free cis-9,cis-12-C18:2 greatly altered Δ12-isomerization. Aldehydes had few effects. Hydroperoxides are responsible, at least in part, for the effects of fat heating: 13HPOD increased trans-10 isomer production (probably by affecting the bacterial community) and decreased trans-11 isomer production by inhibiting Δ12-isomerase activity, whereas 9HPOD inhibited both isomerases.

Effect of permeation enhancers on transdermal delivery of fluoxetine: In vitro and in vivo evaluation

The aim of this study was to investigate the feasibility of transdermal fluoxetine (FX) delivery. The effects of chemical forms (base or salt) and permeation enhancers on in vitro skin permeation of FX were assessed using hairless mouse, rat and human cadaver skin. The optimized formulations from the in vitro studies were then evaluated in an in vivo pharmacokinetic study in rats. The in vitro skin permeation studies suggested that the FX base (FXB) and isopropyl myristate (IPM)-limonene mixture could be suitable for transdermal delivery of FX. The permeation parameters of FX through human cadaver skin were well correlated with that through hairless mouse and rat skin, suggesting that these animal models can be used for predicting the permeability of FX through human skin. After transdermal administration of FX with IPM or the IPM-limonene mixture to rats, the mean steady-state plasma concentration (Css) was 66.20 or 77.55 ng/mL, respectively, which was maintained over 36 h and had a good correlation with the predicted Css from the in vitro data. These in vitro and in vivo data demonstrated that permeation enhancers could be a potential strategy for transdermal delivery of FX.

Chemical equilibrium modeling of copper precipitation in a hyper-concentrated solid-liquid system

Rapid progress has been made recently in the understanding of heavy metal sorption and speciation on sediment and soils. One aspect that was overlooked in the previous studies was the process of pollutant transformation and transportation in hyper-concentrated solid-liquid systems. In this paper, batch experiments on copper sorption in association with loess at high sediment concentrations were conducted. However, some reaction mechanisms were difficult to determine experimentally due to the limitations of speciation extraction methods. In an additional study, the MINTEQA2 chemical equilibrium model was used to calculate the speciation and precipitation of copper sorption by loess to give quantitative predictions and detailed information about the reaction process. The experiments and the modeling simulation were made under the same sorption conditions, with sediment concentrations ranging from 50 to 200 kg/m3 and adsorbates of CuSO4 and Cu(NO3)2, in order to compare their results. The modeling results clearly supported the experimental results, fully explained the mechanisms of the effects of chemical form and sediment concentration on the copper sorption, and strengthened the dominant role of carbonates among the main components of loess in the process of copper sorption.

Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part II. Effects of chemical form and valence

Alkali and alkaline earth metallic (AAEM) species (Na, Mg and Ca) exist in Victorian brown coal mainly as carboxylates forming a part of the coal organic matter or as dissolved salt (NaCl) in the coal moisture. The experimental results in this paper show that the chemical and/or physical form of sodium in the brown coal is an important factor influencing the volatilisation of sodium during pyrolysis. Significant amounts of light species containing carboxyl or carboxylate groups such as formate, acetate and oxalate were found in the volatiles from the pyrolysis of the brown coal. It is believed that the release of AAEM carboxylates is an important mechanism for the volatilisation of AAEM species, particularly at low temperatures (<600°C). The carrier gas flow rate passing through the coal bed can greatly affect the volatilisation of AAEM species through this mechanism. Another mechanism for the volatilisation of AAEM species is the breakage of bonds between AAEM species and char matrix at high temperatures. Under our experimental conditions, the sodium in the form of NaCl in the coal substrate seems to volatilise more easily than the sodium in the form of carboxylate in the coal substrate. The monovalent species (Na) is volatilised much more easily that the divalent species (Mg and Ca) during pyrolysis.

Determination of Technetium-99 in Aqueous Solutions by Inductively Coupled Plasma Mass Spectrometry: Effects of Chemical Form and Memory

The effects of chemical form and instrumental memory on the determination of technetium-99 ( 99 Tc) in aqueous environmental samples by ICP-MS were investigated. Using an assortment of cationic, anionic and neutral Tc and Re complexes, a comparison of the ICP-MS method with the established methods of liquid scintillation counting (LSC) for Tc and neutron activation analysis (NAA) for Re gave lower than expected Tc and Re values by ICP-MS owing to loss of sample in the delivery system. Oxidation of the complexes prior to analysis and the addition of Triton X-100 to the sample solution eliminated this problem. Instrumental memory, resulting from interactions of 99 Tc with the peristaltic pump tubing and the alumina injection port tube, caused significant increases in the background count rate during analysis. Aspiration with a nitric acid solution between sample runs to clean the system effectively eliminated this problem. These techniques were applied to simulated tap water and actual river water samples, and the accuracy was assessed through LSC and spike recovery experiments. The detection limit of the ICP-MS method was found to be 0.6 ppt with an RSD of less than 10%, and these results were within 4% of the LSC results. The sensitivity of the ICP-MS method for the determination of 99 Tc is much superior to that of the alternative radioanalytical methods when accounting for the data acquisition time for identical, low-concentration samples such as are often found in the environment.

Effect of Chemical Form of Mercury on the Performance of Dosed Soils in Standard Leaching Protocols: EP and TCLP

ABSTRACT Application of the EP (Extraction Procedure) and TCLP (Toxicity Characteristic Leaching Procedure) to a variety of mercury-contaminated soils and solid wastes from U.S. Department of Energ...

Effects of Chemical Form and Dosage on the Incorporation of Selenium into Tissue Proteins in Rats

We investigated the incorporation of Se into the proteins of liver and muscle, the two main Se pools, during replenishment of Se-deficient rats with normal or large doses of 75Se-labeled selenite and selenomethionine, doses equivalent to the amounts ingested from a diet with 0.2 or 2 mg Se/kg. With the higher intake, Se levels were elevated. More Se was retained from selenomethionine than from selenite. After separation of the labeled proteins, it was apparent that the higher tissue Se contents were mainly due to nonspecific incorporation into a large number of proteins. We observed no differences between the two chemical forms with regard to the formation of the specific selenoproteins. The 10-fold increase in the Se supply led to a relatively small rise in the levels of these compounds. The results indicate that after ingestion of normal amounts of selenite nearly all of the element is present in the specific selenoproteins. With increasing doses a part is also incorporated nonspecifically into numerous other proteins. In the case of selenomethionine, a part of the element follows the same metabolic pathways, but a percentage is also deposited directly and nonspecifically into proteins in place of methionine.

Inhibition of liver, kidney, and erythrocyte δ-aminolevulinic acid dehydratase (porphobilinogen synthase) by gallium in the rat

Selective inhibition of enzymes in the heme biosynthesis pathway with concomitant urinary excretion of heme precursors serve as potentially important biological markers of chemical exposure and cell injury. Intratracheal administration of gallium arsenide particulate suspensions has been shown to result in inhibition of delta-aminolevulinic acid dehydratase (ALAD) in several tissues and increased excretion of the heme precursor aminolevulinic acid (ALA). This study was undertaken to evaluate in vivo the role of gallium alone in ALAD inhibition and increased urinary excretion of ALA. Male CD rats received a single ip injection of Ga2(SO4)3 at doses of 12.5, 25, 50, 100, and 200 mg Ga/kg. A dose-dependent inhibition of ALAD was observed 24 hr later in liver, kidney, and erythrocytes. After injection of 25 mg Ga/kg, maximal inhibition (42 to 49% of control) of ALAD occurred between 6 and 24 hr in liver and kidney with full recovery of activity at 96 hr. In erythrocytes, maximal inhibition (48% of control) occurred between 24 and 48 hr with recovery of activity at 96 hr. Mild to moderate renal proximal tubular necrosis in the pars recta was observed 24 hr after administration of 100 and 200 mg/kg, but no histopathologic changes were evident at lower doses. No consistent changes in urinary excretion of ALA were observed. Lineweaver-Burk analyses of renal and hepatic ALAD activities in the absence and presence of gallium indicated that the inhibition of ALAD by this element is noncompetitive (same Km, decreased Vmax). Gallium was shown to possess an inhibition constant (Ki) of approximately 3 microns for ALAD, similar to the Ki obtained for lead in other studies. Incubation of ALAD in vitro with gallium and lead, an active thiol group inhibitor, resulted in a greater inhibition of the enzyme. Further in vitro studies demonstrated the attenuation of gallium inhibition of hepatic and renal ALAD by zinc, suggesting that the mechanism of gallium action may involve competition for or displacement of zinc from the sulfhydryl group of the enzyme active site. Since ALAD inhibition occurred at doses at which no histopathologic changes were evident, the determination of ALAD activity in various tissues, including blood, may be of potential value as a biomarker of exposure/toxicity to metals such as gallium. The effect of chemical form and route of exposure of gallium and effects of other Group III metals on inhibition of ALAD and excretion of ALA is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of cadmium, lead and zinc in aerosols by laser-induced breakdown spectrometry

The repetitive breakdown spark from an Nd: YAG laser was used to generate analytical emission spectra of cadmium, lead and zinc in aerosols. The laser was typically operated at a pulse rate of 10 Hz, with an energy of 100 mJ per pulse and a pulse width of approximately 15 ns. Samples were generated in aerosol form by a nebuliser-heat chamber arrangement. The detection apparatus consisted of a monochromator, photomultiplier tube and boxcar averager. The last component provided amplification, averaging and time resolution. Detection limits for cadmium, lead and zinc in aerosols were 0.019, 0.21 and 0.24 µg g–1, respectively, at a signal to noise ratio of 3. The detection limits for cadmium and zinc were well below the threshold limit value-time weighted average (TLV-TWA) and threshold limit value-short-term exposure limit (TLV-STEL) limits for these two metals. Calibration graphs covering two orders of magnitude were generated. The excitation temperature of the plasma was measured from 20 to 40 µs after plasma initiation using the two-line Boltzman method, and was found to decrease from 6500 K at 20 µs to 5150 K at 40 µs. The effects of chemical form and sodium on the spectroscopic signals were investigated.

Accumulation of Co by abalone I-effect of chemical form.

The appearance of radioactive Co in the liver of abalone from sea water was examined to consider the effect of chemical forms of Co(CoCl2 and cyanocobalamin; vitamin B12) in sea water upon the metabolisms in marine organisms. Organic 57Co(cyanocobalamin) from sea water appeared in the liver of abalone combining with a constituent with a molecular weight of 4 × 104. The constituent had the activity of vitamin B12, while inorganic 60Co(CoCl2) appeared combining with three constituents with molecular weights more than or equal to 1.5 × 106, 7 × 103 and less than or equal to 1.5 × 103 which did not show the activities of vitamin B12. The effect of chemical forms of Co in sea water is significant in its accumulation by some species of marine organisms.

Accumulation of Co by several species of marine bivalves.

To clarify the effect of chemical form on the accumulation of Co by organisms, a rearing experiment was performed, using 60 Co (CoCl2) as an inorganic compound and 57 Co cyanocobalamin as an organic one. The concentration factor of inorganin 60 Co for Gomphina melanaegis was calculated to be 360 and that of organic 57 Co was 650. The effect of the difference of chemical form was not large in the accumulation of Co by bivalves. The excretion curveof 60 Co consisted of one component, while that of 57 Co by bivalves. The effective half of 60 Co was 31 days and that fo the longer component of 57 Co in the body of G. melanegis was 98 days. A remarkably different distribution of Co was observed in the gills, liver, and kidney, suggesting different metabolism processes dus to the chemical forms in the organs of the bivalves. On the gel filtration profile of Co in the liver of G. melanaegis, inorganic 60 Co was incorporated in two constituents and organic 57 Co was in one compounent. Four species of bivalves G. melanaegis, Tridacna crocea, Spisula sachalinensis and Patinopecten yessoensis showed two peaks of 60 Co in the gel filtration profiles of their livers, while Anadara broughtonii and japonica showed three peaks.

Manganese Retention in Rats Fed Different Diets and Chemical Forms of Manganese

The effect of chemical form and diet on manganese retention was studied in rats using two diets. The corn-skim milk low-manganese diet was fed to three groups of male, weanling albino rats and a purified manganese-free casein-dextrose diet was fed to three other groups. After 7 days on the diets one group on each diet received orally either 5 4MnCl2, MnCl2 plus carrier manganese as MnCl2 in the dose, or 5 4MnC03 which contained MnC03 as a carrier in the dose. The third day after dosing, the rats were sacrificed and samples of liver, kidneys, semitendinosus muscle and tibia were taken for 5 4Mn and stable manganese analysis. Tissue 5 4Mn contents from rats fed the insoluble carbonate form were the same as from those given soluble chloride, indicating these chemical forms did not affect manganese availability or metabolism. Diet had a large effect on both 5 4Mn and stable manganese content of the tissues. Rats fed the corn-skim milk diet had many times more s Mn and stable manganese in the tissues than did rats given the purified diet. These are extraordinary differences since homeostatic mechanisms normally keep tissue manganese levels remarkably constant. On a weight-adjusted basis, both liver and kidney weights were less in rats on the corn-skim milk diet than in rats fed the purified diet. The results show that type of diet can greatly influence the results of manganese availability and retention studies and also may overcome homeostatic mechanisms which normally keep tissue manganese levels relatively constant.

The Effect of Chemical Form on the Clearance of 239-Plutonium from the Respiratory System of the Rat

Abstract This study has investigated the effect of chemical form on the tissue distribution and excretion of plutonium following its deposition in the respiratory system of the rat. Solutions of various chemical forms of plutonium (nitrate, citrate, oxalate, dioxide, DTPA complex) have been administered to rats by intubation into the nasopharyngeal, tracheobronchial or pulmonary regions of the respiratory tract. The injection volume was less than 3 μl and the activity administered (2–3 nCi kg−1) was comparable to a few maximum permissible body burdens of plutonium in man. The absorption of both plutonium nitrate and citrate from the pulmonary region was approximately four times greater than the absorption from either the tracheobronchial or nasopharyngeal regions. However, of the plutonium deposited in any of the three regions, the relative proportion that is translocated to other tissues is greater following administration as citrate than nitrate (approximately in the ratio of 1.6:1). The absorption of various chemical forms of plutonium from the pulmonary region was in general agreement with the conclusions of the ICRP Task Group on Lung Dynamics. About 13% of activity entering the blood during the first week after administration of plutonium nitrate or citrate was retained in the liver at 7 days implying that plutonium was circulating in the blood in a “monomeric” form. The cumulative excretion of plutonium in the urine in the same period was equivalent to about 4 of the total activity deposited in tissues from the blood. The experimental results suggest that this value could be used for calculating the total tissue deposit from urinary excretion measurements.