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Atomic Absorption Spectroscopy (atomic + absorption_spectroscopy)
Selected AbstractsA Binuclear Phthalocyanine Containing Two Different MetalsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2003Mario Calvete Abstract The unsymmetrical binuclear phthalocyanine 4a and the symmetrical binuclear phthalocyanine 4b with two different metals (Ni and Cu), as well as the correspondent binuclear phthalocyanines with two Ni atoms (4c and 4d) were synthesized from the benzoannulated dicyano-substituted Ni phthalocyanine 2. Atomic absorption spectroscopy verified unambiguously the presence of Ni and Cu in the binuclear phthalocyanines. The proposed synthetic route demonstrates great versatility towards substitution at the peripheral positions of the ring and the variation of the chelating central metal. Complexes 4a,4d are soluble in common organic solvents of medium polarity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Determination of the metal ion dependence and substrate specificity of a hydratase involved in the degradation pathway of biphenyl/chlorobiphenylFEBS JOURNAL, Issue 4 2005Pan Wang BphH is a divalent metal ion-dependent hydratase that catalyzes the formation of 2-keto-4-hydroxypentanoate from 2-hydroxypent-2,4-dienoate (HPDA). This reaction lies on the catabolic pathway of numerous aromatics, including the significant environmental pollutant, polychlorinated biphenyls (PCBs). BphH from the PCB degrading bacterium, Burkholderia xenoverans LB400, was overexpressed and purified to homogeneity. Atomic absorption spectroscopy and Scatchard analysis reveal that only one divalent metal ion is bound to each enzyme subunit. The enzyme exhibits the highest activity when Mg2+ was used as cofactor. Other divalent cations activate the enzyme in the following order of effectiveness: Mg2+ > Mn2+ > Co2+ > Zn2+ > Ca2+. This differs from the metal activation profile of the homologous hydratase, MhpD. UV-visible spectroscopy of the Co2+,BphH complex indicates that the divalent metal ion is hexa-coordinated in the enzyme. The nature of the metal ion affected only the kcat and not the Km values in the BphH hydration of HPDA, suggesting that cation has a catalytic rather than just a substrate binding role. BphH is able to transform alternative substrates substituted with methyl- and chlorine groups at the 5-position of HPDA. The specificity constants (kcat/Km) for 5-methyl and 5-chloro substrates are, however, lowered by eight- and 67-fold compared with the unsubstituted substrate. Significantly, kcat for the chloro-substituted substrate is eightfold lower compared with the methyl-substituted substrate, showing that electron withdrawing substituent at the 5-position of the substrate has a negative influence on enzyme catalysis. [source] Altered Cbfal expression and biomineralization in an osteosarcoma cell lineJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2004H. Perinpanayagam Abstract Osteoblast differentiation and expression are regulated by Cbfal transcription factors. Recent evidence suggests that Cbfal may also regulate bone mineralization. The purpose of this study was to characterize Cbfal expression in relation to mineralization in rat UMR106-01 osteoblastic cell cultures. UMR106-01 BSP cultures consistently form bone-like mineral, whereas the UI subclone mineralize gradually. BSP and UI cultures were grown for 48 h and then treated with ,-glycerophosphate. BSP cultures had alizarin red stained calcifications and mineral-like deposits within 24 h of phosphate. Atomic absorption spectroscopy measured significantly (P < 0.0001) more calcium in the phosphate-treated BSP cultures than in the UI. Cbfal message was detected in the BSP and UI cultures, but the Cbfal N-terminal isoform was deficient in UI and appeared to be up-regulated in the phosphate-treated BSP cultures. Cbfal protein levels were also reduced in the UI. DNA sequence from the RT-PCR products was utilized to design Taqman Real-time RT-PCR reagents. Quantitative Real-time RT-PCR analysis showed that Cbfal mRNA levels relative to endogenous 18 s rRNA were lower in the slower mineralizing UI cultures. Furthermore, the Cbfal N-terminal isoform mRNA levels were significantly (P < 0.001) lower in the slower mineralizing cultures. Transfection with Cbfal or isoform antisense caused a significant (P < 0.001) reduction in mineralization. Therefore, Cbfal expression may be associated with bone-like mineral formation in rat UMR106-01 osteoblastic cell cultures. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] A Study of Nafion-Coated Bismuth-Film Electrode for the Determination of Zinc, Lead, and Cadmium in Blood SamplesELECTROANALYSIS, Issue 21 2008Benzhi Liu Abstract In this article a sensitive differential pulse stripping voltammetry technique on Nafion-coated bismuth-film electrode (NCBFE) was studied for the simultaneous determination of zinc, cadmium, and lead ions in blood samples at ultra trace levels. The measurement results were in excellent agreement with those obtained from atomic absorption spectroscopy. Various operational parameters were investigated and discussed in terms of their effect on the measurement signals. Under optimal conditions, calibration curves for the simultaneous determination of zinc, cadmium, and lead ions were achieved, based on three times the standard deviation of the baseline, the limits of detection were 0.09,,g L,1 for Cd(II), 0.13,,g L,1 for Pb(II), and 0.97,,g L,1 for Zn(II) respectively. [source] Properties of Poly(sodium 4-styrenesulfonate)-Ionic Liquid Composite Film and Its Application in the Determination of Trace Metals Combined with Bismuth Film ElectrodeELECTROANALYSIS, Issue 5 2008Jianbo Jia Abstract A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4-styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)64,/Fe(CN)63, can be effectively improved at the PSS-BMIMPF6 modified GC. The bismuth modified PSS-BMIMPF6 composite film electrodes (GC/PSS-BMIMPF6/BiFEs) displayed high mechanical stability and sensitive stripping voltammetric performances for the determination of trace metal cations. The GC/PSS-BMIMPF6/BiFE exhibited well linear response to both Cd(II) and Pb(II) over a concentration range from 1.0 to 50,,g L,1. And the detection limits were 0.07,,g L,1 for Cd(II) and 0.09,,g L,1 for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120,s, respectively. Finally, the GC/PSS-BMIMPF6/BiFEs were successfully applied to the determination of Cd(II) and Pb(II) in real sample, and the results of present method agreed well with those of atomic absorption spectroscopy. [source] Absorption of copper(II) by creosote bush (Larrea tridentata): Use of atomic and x-ray absorption spectroscopyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Jorge Luis Gardea-Torresdey Abstract Larrea tridentata (creosote bush), a common North American native desert shrub, exhibits the ability to take up copper(II) ions rapidly from solution. Following hydroponic studies, U.S. Environmental Protection Agency method 200.3 was used to digest the plant samples, and flame atomic absorption spectroscopy (FAAS) was used to determine the amount of copper taken up in different parts of the plant. The amount of copper(II) found within the roots, stems, and leaves was 13.8, 1.1, and 0.6 mg/g, respectively, after the creosote bush was exposed to a 63.5-ppm copper(II) solution for 48 h. When the plant was exposed to a 635-ppm copper(II) solution, the roots, stems, and leaves contained 35.0, 10.5, and 3.8 mg/g, respectively. In addition to FAAS analysis, x-ray microfluorescence (XRMF) analysis of the plant samples provided further confirmation of copper absorption by the various plant parts. X-ray absorption spectroscopy (XAS) elucidated the oxidation state of the copper absorbed by the plants. The copper(II) absorbed from solution remained as copper(II) bound to oxygen-containing ligands within the plant samples. The results of this study indicate that creosote bush may provide a useful and novel method of removing copper(II) from contaminated soils in an environmentally friendly manner. [source] Surface Activation of a Ferrimagnetic Glass,Ceramic for Antineoplastic Drugs GraftingADVANCED ENGINEERING MATERIALS, Issue 7 2010Enrica Vernè A ferrimagnetic glass,ceramic, belonging to the system SiO2,Na2O,CaO,P2O5,FeO,Fe2O3, has been studied as potential carrier for antineoplastic agents, in order to exploit the combination of hyperthermia and chemotherapy. Different material pre-treatments, such as ultrasonic washing, water, or simulated body fluid dipping, were evaluated to promote the surface activation of the glass,ceramic, i.e., the hydroxyl groups formation on it. X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectrometry, and wettability measurements were performed to observe the samples surface modification. The best results in terms of free hydroxyl groups exposition were obtained by dipping the samples in distilled water for 7 days at 37,°C. Two different anticancer drugs were selected in order to test the reactivity of the activated surface: cisplatinum and doxorubicin. The uptake and release of doxorubicin and cisplatinum were evaluated on glass,ceramic powders, by using UV,Visible spectrometry and graphite furnace atomic absorption spectroscopy, respectively. After 1 day of uptake at 37,°C, the quantity of doxorubicin incorporated into the glass,ceramic is 77,±,7 wt%, while only 42,±,9.6 wt% of cisplatinum is grafted onto the material surface. For both antitumoral agents, the maximum drug release after soaking in aqueous solutions at 37,°C was obtained in few hours, with a randomly distributed kinetics trend. [source] Physical characterization of plakophilin 1 reconstituted with and without zincFEBS JOURNAL, Issue 14 2000Ilse Hofmann Plakophilin 1 (PKP1) belongs to the arm -repeat protein family which is characterized by the presence of a conserved 42-amino-acid motif. Despite individual members of the family containing a similar type of structural domain, they exhibit diverse cellular functions. PKP1 is ubiquitously expressed in human tissues and, depending on the type of cell, found prominently in the karyoplasm and/or in desmosomes. In surface plasmon resonance detection experiments, we noticed that PKP1 specifically bound zinc but not calcium or magnesium. Therefore we have used circular dichroism spectroscopy, limited proteolysis, analytical ultracentrifugation, electron microscopy and dynamic light scattering to establish the physical properties of recombinant PKP1 depending on the presence or absence of zinc. The , helix content of PKP1 was considerably higher when reconstituted with zinc than without. By atomic absorption spectroscopy 7.3 atoms zinc were shown to be tightly associated with one molecule of wild-type PKP1. The zinc-reconstituted protein formed globular particles of 21.9 ± 8.4 nm diameter, as measured by electron microscopy after glycerol spraying/rotary metal shadowing. In parallel, the average sedimentation coefficient (s20,w) for zinc-containing PKP1 was 41S and its diffusion coefficient, as obtained by dynamic light scattering, 1.48 × 10,7 cm2·s,1. The molecular mass of 2.44 × 106 obtained from s and D yields an average stoichiometry of 30 for the PKP1 oligomer. In contrast, PKP1, reconstituted without zinc, contained no significant amount of zinc, sedimented with 4.6S, and was present in monomeric form as determined by sedimentation equilibrium centrifugation. [source] Metals in human placenta: focus on the effects of cadmium on steroid hormones and leptin,JOURNAL OF APPLIED TOXICOLOGY, Issue 3 2010Sandra Stasenko Abstract Cadmium and other metallic ions can act as metalloestrogens and endocrine disruptors of reproductive tissues and fetal development in mammals, including humans. The detrimental effects occur with respect to the synthesis of both steroid and polypeptide hormones in the placenta. Leptin is produced by the trophoblast and may regulate fetal organogenesis and development. In human term placentas, concentrations of toxic metals and their effects on steroidogenesis were assessed in healthy parturients (109 non-smokers and 99 smokers) in relation to tobacco smoking. Trace elements (cadmium, lead, iron, zinc and copper) were analyzed in placentas using atomic absorption spectroscopy, and steroid hormones (progesterone and estradiol) were assayed in placental samples by an enzyme-immunometric method. Cadmium concentrations were doubled in placentas of smokers as compared with non-smokers, and placental lead and zinc concentrations increased significantly. Placental concentrations of iron, copper, progesterone and estradiol did not differ. In addition, human trophoblast cells were co-cultured with 0, 5, 10 or 20,,µm CdCl2 for 96,,h and leptin mRNA assessed by quantitative polymerase chain reaction. Leptin mRNA declined dose-responsively as a result of CdCl2 exposure. Collectively, the results confirm that human placental tissue offers a unique opportunity to biomonitor cadmium exposure in both the maternal and the internal fetal environments. In addition, the results strongly suggest that cadmium may cause a decline in placental leptin synthesis, as we have previously shown for placental progesterone production. This may constitute further evidence of the endocrine-disrupting effects of cadmium, as a constituent of tobacco smoke, on reproduction in women. Copyright © 2009 John Wiley & Sons, Ltd. [source] Liver cell transplantation leads to repopulation and functional correction in a mouse model of Wilson's diseaseJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 11 2004KATRINA J ALLEN Abstract Background and Aim:, The toxic milk (tx) mouse is a non-fatal animal model for the metabolic liver disorder, Wilson's disease. The tx mouse has a mutated gene for a copper-transporting protein, causing early copper accumulation in the liver and late accumulation in other tissues. The present study investigated the efficacy of liver cell transplantation (LCT) to correct the tx mouse phenotype. Methods:, Congenic hepatocytes were isolated and intrasplenically transplanted into 3,4-month-old tx mice, which were then placed on various copper-loaded diets to examine its influence on repopulation by transplanted cells. The control animals were age-matched untransplanted tx mice. Liver repopulation was determined by comparisons of restriction fragment length polymorphism ratios (DNA and mRNA), and copper levels were measured by atomic absorption spectroscopy. Results:, Repopulation in recipient tx mice was detected in 11 of 25 animals (44%) at 4 months after LCT. Dietary copper loading (whether given before or after LCT, or both) provided no growth advantage for donor cells, with similar repopulation incidences in all copper treatment groups. Overall, liver copper levels were significantly lower in repopulated animals (538 ± 68 µg/g, n = 11) compared to non-repopulated animals (866 ± 62 µg/g, n = 14) and untreated controls (910 ± 103 µg/g, n = 6; P < 0.05). This effect was also seen in the kidney and spleen. Brain copper levels remained unchanged. Conclusion:, Transplanted liver cells can proliferate and correct a non-fatal metabolic liver disease, with some restoration of hepatic copper homeostasis after 4 months leading to reduced copper levels in the liver and extrahepatic tissues, but not in the brain. [source] Mapping the intake of different elements in vegetal tissues by dual-energy X-ray imaging at Da,ne synchrotron light sourceMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2008L. Reale Abstract This article reports on the first utilization of the soft X-ray beamline at the Da,ne synchrotron light source for mapping the intake of different elements in plant tissues. As a test, the method of dual-energy X-ray microradiography was applied to the investigation of the natural sulfur content in dried leaf and root samples. Our ultimate goal was to monitor the pollutant lead and its intake, which was added in controlled doses to the hydroponic medium of laboratory-controlled samples of vegetal species. The results obtained by the nondestructive X-ray radiographic analysis are compared to the values of concentrations determined by a standard chemical analysis utilizing atomic absorption spectroscopy. From this comparison the validity of the X-ray detection of heavy metals in biological samples has been confirmed. The superposition of the dual energy results on the simple planar radiography shows the representation of the pollutant intake directly on the sample structures. It should be pointed out that this method, developed here for plant root and leaves could be applied to any biological sample of interest, but the preparation and observation conditions necessitate different strategies according to the type of sample under analysis. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source] Lead exposure in mexican radiator repair workersAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 3 2002Ronald Dykeman Abstract Background Lead exposure was investigated among 73 Mexican radiator repair workers (RRWs), 12 members of their family (4 children and 8 wives), and 36 working controls. RRWs were employed at 4 radiator repair shops in Mexico City and 27 shops in Cuernavaca and surrounding areas. Methods Exposure was assessed directly through the use of personal air sampling and hand wipe samples. In addition, industrial hygiene inspections were performed and detailed questionnaires were administered. Blood lead levels were measured by graphite furnace atomic absorption spectroscopy (AAS). Results The mean (SD) values for blood lead of the RRWs, 35.5 (13.5) ,g/dl, was significantly greater than the same values for the working controls, 13.6 (8.7) ,g/dl; P,<,001. After excluding a single outlier (247 ,g/m3), air lead levels ranged from 0 to 99 ,g/m3 with a mean (SD) value of 19 (23) ,g/m3 (median,=,7.9 ,g/m3). In a final multivariate regression model of elevated blood lead levels, the strongest predictors were smoking (vs. non-smoking), the number of radiators repaired per day on average, and the use (vs. non-use) of a uniform while at work, which were associated with blood lead elevations of 11.4 ,g/dl, 1.95 ,g/dl/radiator/day, and 16.4 ,g/dl, respectively (all P,<,.05). Uniform use was probably a risk factor because they were not laundered regularly and consequently served as reservoir of contamination on which RRWs frequently wiped their hands. Conclusions Lead exposure is a significant problem of radiator repair work, a small industry that is abundant in Mexico and other developing countries. Am. J. Ind. Med. 41:179,187, 2002. © 2002 Wiley-Liss, Inc. [source] GEOCHEMICAL ANALYSIS OF VITREOUS ROCKS EXPLOITED DURING THE FORMATIVE PERIOD IN THE ATACAMA REGION, NORTHERN CHILE,ARCHAEOMETRY, Issue 1 2009A. SEELENFREUND Petrographic analysis and geochemical characterization studies were carried out on vitreous dacite and/or rhyodacite artefacts from Formative period archaeological sites in the upper Salado River Basin in the Atacama Desert, northern Chile. These were compared with samples taken from two source areas located within the subregion, named Linzor and Paniri. Source samples and archaeological specimens were analysed by inductively coupled plasma , mass spectrometry (ICP,MS) combined with optical emission plasma , mass spectrometry (ICP,OES) and atomic absorption spectroscopy (AAS). Results from the limited number of samples analysed indicate that the Linzor source seems to have been the primary source exploited during the Early and Late Formative periods in the Salado River Basin. [source] Structure of Thermotoga maritima TM0439: implications for the mechanism of bacterial GntR transcription regulators with Zn2+ -binding FCD domainsACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2009Meiying Zheng The GntR superfamily of dimeric transcription factors, with more than 6200 members encoded in bacterial genomes, are characterized by N-terminal winged-helix DNA-binding domains and diverse C-terminal regulatory domains which provide a basis for the classification of the constituent families. The largest of these families, FadR, contains nearly 3000 proteins with all-,-helical regulatory domains classified into two related Pfam families: FadR_C and FCD. Only two crystal structures of FadR-family members, those of Escherichia coli FadR protein and LldR from Corynebacterium glutamicum, have been described to date in the literature. Here, the crystal structure of TM0439, a GntR regulator with an FCD domain found in the Thermotoga maritima genome, is described. The FCD domain is similar to that of the LldR regulator and contains a buried metal-binding site. Using atomic absorption spectroscopy and Trp fluorescence, it is shown that the recombinant protein contains bound Ni2+ ions but that it is able to bind Zn2+ with Kd < 70,nM. It is concluded that Zn2+ is the likely physiological metal and that it may perform either structural or regulatory roles or both. Finally, the TM0439 structure is compared with two other FadR-family structures recently deposited by structural genomics consortia. The results call for a revision in the classification of the FadR family of transcription factors. [source] Serum selenium concentration in healthy children living in TehranBIOFACTORS, Issue 2 2007Reza Safaralizadeh Abstract Introduction: Selenium is one of the essential trace elements which is more notifed in children in recent years. Reliable age-specifc reference values for selenium in children in Iran are not clear and are important for the identifcation of selenium defciency and some other researches that is the aim of this study. Methods: Serum samples of 216 healthy children were analyzed by using hydride generation and flame atomic absorption spectroscopy to measured selenium level. Results: The mean and standard deviation of serum selenium level in children 0,16 years old (mean: 39.83 months) was 72.14 ± 16.80 ,g/l. There was signifcant difference in serum selenium concentration between two sexes which was 76.78 ± 15.24 ,g/l and 69.56 ± 17.09 ,g/l in girls and boys respectively (P value = 0.002 ). There was also a positive correlation between higher selenium serum concentration and age in both sexes. Conclusion: Essential trace element's normal ranges are fundamental data which could use in many studies. Serum selenium concentration in healthy Iranian children that found in this study is very close to serum concentration of European children. Our fndings may reveal nutritional culture's similarity. [source] Malonate-bound structure of the glycerophosphodiesterase from Enterobacter aerogenes (GpdQ) and characterization of the native Fe2+ metal-ion preferenceACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2008Colin J. Jackson The structure of a malonate-bound form of the glycerophosphodiesterase from Enterobacter aerogenes, GpdQ, has been refined at a resolution of 2.2,Å to a final R factor of 17.1%. The structure was originally solved to 2.9,Å resolution using SAD phases from Zn2+ metal ions introduced into the active site of the apoenzyme [Jackson et al. (2007), J. Mol. Biol.367, 1047,1062]. However, the 2.9,Å resolution was insufficient to discern significant details of the architecture of the binuclear metal centre that constitutes the active site. Furthermore, kinetic analysis revealed that the enzyme lost a significant amount of activity in the presence of Zn2+, suggesting that it is unlikely to be a catalytically relevant metal ion. In this communication, a higher resolution structure of GpdQ is presented in which malonate is visibly coordinated in the active site and analysis of the native metal-ion preference is presented using atomic absorption spectroscopy and anomalous scattering. Catalytic implications of the structure and its Fe2+ metal-ion preference are discussed. [source] A model to quantify encrustation on ureteric stents, urethral catheters and polymers intended for urological useBJU INTERNATIONAL, Issue 4 2000S.K.S. Choong Objective To validate an encrustation model and to quantify encrustation on currently used urological devices and polymers intended for urological use. Materials and methods An encrustation model was validated: (i) to measure the amount of calcium leaching from the glass model and from the polymer used; (ii) to determine whether the use of a single-source or pooled urine produced similar results; (iii) to determine in vitro encrustation; and (iv) to compare the results of in vivo implantation of the same materials into the bladders of rodents with the in vitro results. A test polymer (a ureteric stent, a urethral catheter or a biomaterial) and a control silicone polymer were housed separately but received human urine from the same reservoir and under the same conditions (pH 6.0 and 37 °C) for 5 days. The amount of calcium encrustation on each polymer was measured using atomic absorption spectroscopy. Each experiment was repeated at least four times and the results expressed as an encrustation index, defined as the ratio of encrustation of the test and reference polymers. Results The amount of calcium leaching from the glass model and polymers tested was insignificant. The use of a single-source or pooled urine gave the same results in the encrustation model. The in vitro results correlated with in vivo implantation of disks into the bladders of rats. Among the commonly used ureteric stents tested, the Cook C-Flex ureteric stents encrusted least. Hydrogel-coated ureteric stents encrusted more than uncoated stents. The Bard polytetrafluoroethylene short-term urethral catheter encrusted more than the Bard hydrogel-coated long-term catheter. A plasma-activated surface modification of a synthetic biomaterial with hyaluronic acid encrusted less than silicone, a long-term biomaterial widely regarded as the ,gold standard'. Conclusion This validated encrustation model is the first to quantify encrustation on currently available ureteric stents and urethral catheters. A novel coating for a biomaterial was identified using the encrustation model, and which encrusted less than silicone. [source] Development of a Method for the Quantification of the Molar Gold Concentration in Tumour Cells Exposed to Gold-Containing DrugsCHEMMEDCHEM, Issue 5 2007Ingo Ott Dr. Abstract The knowledge of the cellular molar concentration of a drug is an extremely important parameter for the discussion and interpretation of its efficacy and bioavailability. Concerning metal complexes, electrothermal atomic absorption spectroscopy (ETAAS) offers a valuable analytical tool. However, matrix effects often hamper proper quantification of the metal concentration in biological tissues. This paper describes the development of an ETAAS method for the quantification of the molar gold concentration in HT-29 colon carcinoma cells. ETAAS analytical conditions were optimised and a factor was developed which allows the calculation of the molar cellular gold concentration from the measured gold per cellular biomass value. The method was used to quantify the gold content in HT-29 cells after exposure to the gold drug auranofin. Results indicated a strong cellular uptake of auranofin (compared to other metal anticancer drugs), which significantly correlated with the antiproliferative effects triggered by this agent. [source] EFFICACY OF SARGASSUM POLYCYSTUM (PHAEOPHYCEAE) SULPHATED POLYSACCHARIDE AGAINST PARACETAMOL-INDUCED DNA FRAGMENTATION AND MODULATION OF MEMBRANE-BOUND PHOSPHATASES DURING TOXIC HEPATITISCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2007HB Raghavendran SUMMARY 1The aim of the present study was to assess the protective effect of Sargassum polycystum (sulphated polysaccharide) extract against paracetamol-induced DNA strand breaks and modulation of membrane-bound phosphatases, protein thiols and inorganic cations during toxic hepatitis. 2Seaweed extract (200 mg/kg per day for 21 days) was administered to male Wistar rats against paracetamol challenge. Serum and liver tissues were used to assess levels of ATPase, protein thiols and inorganic cations using atomic absorption spectroscopy. The fragmentation of DNA was assessed by agarose gel electrophoresis. 3Paracetamol induced intracellular stress, accompanied by changes in the structural and functional characteristics of liver cell membranes, which affected DNA integrity, membrane-bound ATPase and inorganic cations homeostasis. Rats intoxicated with paracetamol (800 mg/kg, i.p.) showed significant impairment in activities of total ATPase, Mg2+ -ATPase, Ca+ -ATPase and Na+/K+ -ATPase, with concomitant changes in the levels of tissue protein thiols and inorganic cations, such as Na+, K+ and Ca2+. These changes were prevented in animals pretreated with S. polycystum extract, which indicates that S. polycystum supplementation could exert some protective effect against paracetamol-induced toxic hepatitis in rats. 4The protective effect of the seaweed extract may be due to the presence of sulphated compounds that have free radical-scavenging activity. [source] | ||||||||||||||||