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PubMed2003

Oxygen depletion during and after mTHPC-mediated photodynamic therapy in RIF1 and H-MESO1 tumors.

During photodynamic therapy (PDT), low oxygenation levels, induced both by oxygen consumption and by vascular occlusion, can lead to an inefficient photochemical reaction that may compromise the efficacy of PDT. In the present studies, tumor oxygenation was measured before, during and after meta-tetrahydroxyphenylchlorin (mTHPC)-mediated PDT of murine RIF1 tumors and human mesothelioma xenografts (H-MESO1). Tumor pO2 was measured in real time with Eppendorf polarography, and the extent of relative hypoxia at specific times was measured by immunohistochemical staining. Significant decreases in median pO2 values, as well as an increase in the number of values below 2.5 mmHg, were seen during and after PDT in RIF1 tumors, although there was a large intertumoral variation. Tumor pO2 values did not change significantly in H-MESO1 tumors. Staining with antibodies against the hypoxia marker EF3 showed significant increases in relative hypoxia after PDT in both tumor types compared with separate groups of untreated controls. Our results are consistent with PDT-induced oxygen depletion (reduced pO2) leading to an increase in relative hypoxia in RIF1 tumors. Extensive necrosis in the H-MESO1 tumors may have prevented the detection of PDT-induced hypoxia using the Eppendorf polarographic needle, whereas immunohistochemistry did reveal increases in relative hypoxia.

Animals↗

PubMed2003

Semi-quantitative "spot-test" of cyanide.

A selective, sensitive, rapid and simple-handling analytical method for the determination of cyanide at low detection limits in surface and underground water, soil and industrial waste samples was developed. The method is based on a reaction, proposed by Guilbault and Kramer, where free cyanide reacts with p-nitrobenzaldehyde to form an intermediate cyanohydrin, which reacts with o-dinitrobenzene to give a highly colored purple compound. The original procedure was modified for application in a small device containing a gas-permeable membrane. The cyanide is converted in the volatile hydrogen cyanide, which permeates through a PTFE membrane, reaching colorimetric reagents. In order to obtain semi-quantitative results, printed color scales were built. The method allows rapid, accurate, selective, low-cost and simple-handling determinations of free cyanide, even in complex samples. About 150 real samples were analyzed. Less than 10 ng of free cyanide per ml (10 microg l(-1)) can be easily detected. For more concentrated solutions, the results had been compared to those obtained using differential pulse polarography. The standard addition method was used for more diluted solutions.

Journal Article↗

PubMed2004

Facilitated sulfate transfer across the nitrobenzene-water interface as mediated by hydrogen-bonding ionophores.

Facilitated SO4(2-) transfers by hydrogen bond-forming ionophores are investigated across the nitrobenzene (NB)-water interface by using polarography with a dropping electrolyte electrode. Bis-thiourea 1, alpha,alpha'-bis(N'-p-nitrophenylthioureylene)-m-xylene, is found to significantly facilitate the transfer of the highly hydrophilic SO4(2-) whereas its counterpart, N-(p-nitrophenyl)-N'-propylthiourea (ionophore 2), cannot. In contrast to the predominant formation of a 1:1 complex with SO4(2-) in the bulk NB phase, the SO4(2-) transfer assisted by 1 is indeed based on the formation of a 1:2 complex between SO4(2-) and ionophore, even under the condition of [SO4(2-)]aq >> [1]org. Such an exclusive formation of the 1:2 (SO4(2-) to ionophore) complex at the NB-water interface is not observed with structurally similar bis-thiourea 3, alpha,alpha'-bis(N'-phenylthioureylene)-m-xylene, where p-nitrophenyl moietes of bis-thiourea 1 are simply replaced by phenyl groups. The facilitated transfer of SO4(2-) with bis-thiourea 1 is further compared to that of HPO4(2-) and H2PO4- across the NB-water interface, which was previously shown to be assisted by 1 through the formation of the 1:1 and 2:1 (anion to ionophore) complexes, respectively. On the basis of these examinations, unique binding behaviors of hydrogen bond-forming ionophores at the NB-water interface are discussed, with a view towards development of ionophore-based anion-selective chemical sensors.

Journal Article↗

PubMedDate not supplied

Sorption interactions between imazaquin and a humic acid extracted from a typical Brazilian oxisol.

Soil sorption of most hydrophobic organic compounds (e.g., nonpolar pesticides) is directly related to soil organic matter (SOM) content. Humic substances are the major SOM components, containing carboxylic, phenolic, amine, quinone, and other functional groups, and specific structural configurations. In this paper, sorption interactions between imazaquin (2-[4,5-dydro-4-methyl-4-(1-methylethyl)-5-oxo-1H- imidazol-2-yl]-3-quinoline-carboxylic acid) herbicide (IM) and a humic acid (HA) extracted from a typical Brazilian Oxisol were studied with electron paramagnetic resonance (EPR) and Fourier-transform infrared (FTIR) spectroscopic techniques. A polarographic technique was used to quantify sorption. The IM amount sorbed on the HA was much higher than that on the whole soil within the pH range studied, emphasizing the prominent role played by SOM on IM sorption. Moreover, IM sorption increased as the soil-solution pH decreased. This enhancement in sorption was attributed to the hydrophobic affinity of the herbicide by the HA and to the electrostatic interaction between the protonated quinoline group of IM and the negative sites of the HA. Hydrophobic regions in the HA's interior at low pH (< 5.0) were recently demonstrated by an EPR detectable spin-label molecule. The FTIR and EPR spectroscopy and polarography data indicated weak interaction between IM and the soil and its HA, involving hydrogen bonding, proton transfer, and cation exchange (at low pH), and mainly hydrophobic interactions. However, no strong reaction mechanism, such as charge transfer, was involved. In addition, this research suggested that soil amendment with organic material might increase magnitude of IM sorption, consequently avoiding leaching and carryover problems usually found for mobile and persistent herbicides such as imazaquin.

Adsorption↗

PubMed2002

Influence of experimental diabetes on the microcirculation of injured peripheral nerve: functional and morphological aspects.

Regeneration of diabetic axons has delays in onset, rate, and maturation. It is possible that microangiopathy of vasa nervorum, the vascular supply of the peripheral nerve, may render an unfavorable local environment for nerve regeneration. We examined local nerve blood flow proximal and distal to sciatic nerve transection in rats with long-term (8 month) experimental streptozotocin diabetes using laser Doppler flowmetry and microelectrode hydrogen clearance polarography. We then correlated these findings, using in vivo perfusion of an India ink preparation, by outlining the lumens of microvessels from unfixed nerve sections. There were no differences in baseline nerve blood flow between diabetic and nondiabetic uninjured nerves, and vessel number, density, and area were unaltered. After transection, there were greater rises in blood flow in proximal stumps of nondiabetic nerves than in diabetic animals associated with a higher number, density, and caliber of epineurial vessels. Hyperemia also developed in distal stumps of nondiabetic nerves but did not develop in diabetic nerves. In these stumps, diabetic rats had reduced vessel numbers and smaller mean endoneurial vessel areas. Failed or delayed upregulation of nerve blood flow after peripheral nerve injury in diabetes may create a relatively ischemic regenerative microenvironment.

Animals↗

PubMed2000

Chemical characteristics and relative bioavailability of supplemental organic zinc sources for poultry and ruminants.

Eight commercially available organic Zn products and reagent-grade ZnSO4 x 7H2O (Zn Sulf) were evaluated by polarographic analysis, and solubility in .1 M K2HPO4-KH2PO4 buffer (pH 5), .2 M HCl-KCl buffer (pH 2), and deionized water. Fractions from these solubility tests were evaluated by gel filtration chromatography for structural integrity. Degree of chelation was generally positively related to chelation effectiveness determined by polarography. The organic sources were Zn methionine complex A (Zn MetA), Zn methionine complex B (Zn MetB), Zn polysaccharide complex (Zn Poly), Zn lysine complex (Zn Lys), Zn amino acid chelate (Zn AA), Zn proteinate A (Zn ProA), Zn proteinate B (Zn ProB), and Zn proteinate C (Zn ProC). Three experiments were conducted to estimate the relative bioavailability of Zn from the organic Zn supplements for chicks and lambs when added at high dietary levels to practical diets. Bone Zn concentration increased (P < .001) as dietary Zn increased in both experiments. When Zn Sulf was assigned a value of 100% as the standard, multiple linear regression slope ratios of bone Zn from chicks fed 3 wk regressed on dietary Zn intake gave estimated relative bioavailability values of 83 +/- 14.6 and 139 +/- 16.9 for Zn AA and Zn ProA, respectively, in Exp. 1 and 94 +/- 11.6, 99 +/- 8.8, and 108 +/- 11.4 for Zn Poly, Zn ProB, and Zn ProC, respectively, in Exp. 2. In Exp. 3, 42 lambs were fed diets containing Zn Sulf, Zn ProA, Zn AA, or Zn MetB for 21 d. Based on multiple linear regression slope ratios of liver, kidney, and pancreas Zn and liver metallothionein concentrations on added dietary Zn, bioavailability estimates relative to 100% for Zn Sulf were 130, 110, and 113 for Zn ProA, Zn AA, and Zn MetB, respectively. Except for Zn ProA, which was greater, the organic Zn supplements had bioavailability values similar to that of Zn Sulf for chicks and lambs. Bioavailability of organic Zn products was inversely related to solubility of Zn in pH 5 buffer in chicks (r2 = .91) and pH 2 buffer in lambs (r2 = .91), but not to an estimate of degree of chelation.

Animal Feed↗

PubMed2004

Use of chemical characteristics to predict the relative bioavailability of supplemental organic manganese sources for broilers.

Twelve organic Mn sources and MnSO4 were evaluated by polarographic analysis and via solubility in buffers (pH 5 and 2) and deionized water. Fractions from solubility tests were evaluated by gel filtration chromatography for structural integrity. Organic Mn sources included five Mn methionine complexes (Mn Met A to Mn Met E), two Mn proteinates (Mn Pro A and Mn Pro B), and five Mn amino acids (Mn AA A to Mn AA E). Sources varied considerably in chemical characteristics. Chelation strength (Qf) ranged from weak (1.9 Qf-values) to strong complexes (115.4 Qf-values). No complexed Mn was found in filtrates at pH 2.0 or 5.0. A 42-d bioassay was used to estimate relative bioavailability of Mn sources for chicks fed diets supplemented with 60, 120, or 180 mg Mn/kg. Bone Mn, heart Mn, heart manganese-superoxide dismutase activity (MnSOD), and heart MnSOD mRNA increased (P < 0.001) as dietary Mn increased. Only heart MnSOD mRNA tended (P < 0.10) to differ among dietary Mn sources. For bioassays of Mn, the MnSOD mRNA level in heart was more sensitive than the MnSOD activity in heart or other indices. Relative to MnSO4 (assigned 100%), slope ratios of MnSOD mRNA levels in heart gave bioavailabilities of 99, 132, and 113% for Mn Met E, Mn AA B, and Mn AA C sources with weak, moderate, and strong chelation strength, respectively. The bioavailability of Mn was more closely related to chelation strength as measured by polarography than to chemical traits assessed by solubility or structural integrity.

Animal Feed↗

PubMed1990

Electrochemical properties as a function of pH for the benzotriazine di-N-oxides.

The electrochemistry of five benzotriazine di-N-oxides has been examined by cyclic voltammetry and differential pulse and dc polarographies as a function of pH. Between the pH range 8.5 and 2 the trend to less negative potentials with lowering of pH can be described by an equation of the type Ep = -apH + b. Comparison has been made with the mono- and zero-N-oxides which were found to show virtually identical trends in electron affinity with pH. The general electrochemical characteristics for the di- and mono-N-oxides under acidic conditions were found to be comparable with the zero-N-oxide. This was particularly the case on repeat scanning in the cyclic voltammetric mode. The redox mechanism involved reduction by a 4-electron addition step and subsequent loss of the N-oxide group(s) yielding the intact benzotriazine heterocycle. The heterocycle was also redox active, involving a reversible 2-electron reduction. For the di-N-oxides these two stages could be identified as separate processes at alkaline pH, but only a single step at acidic values. The mono-N-oxide in which the electrochemical behaviour was dominated by the triazine, showed only a single reduction step, although the single N-oxide group was redox active.

Antineoplastic Agents↗

PubMed1994

Tumor oxygenation after 1) carbogen and/or perflubron emulsion administration in tumor xenografts 2) carbogen administration in patients.

This study examines the changes in tumor pO2 distribution assessed by polarography (KIMOC 6650, Eppendorf) in 1) two human tumor xenografts after carbogen inhalation with or without a perflubron (perfluorooctylbromide) emulsion (Oxygent, Alliance Pharmaceutical corp.) and in 2) human head and neck carcinomas after carbogen inhalation. Mice bearing HRT18 or NA11+ tumors were restrained and their body temperature was kept constant. Perflubron emulsion (4 ml/kg) was injected i.v. in the mice. In patients, oxygenation of the head and neck metastatic lymph nodes was assessed before and/or during carbogen exposure. The distribution of pO2 values shifted upwards during carbogen exposure in both animals and patients while the proportion of low pO2 values decreased. The maximal effect was obtained with patients after 1 to 6 minutes of carbogen exposure, but 4 patients still maintained very low pO2s. Carbogen plus 4 ml/kg perflubron emulsion was more efficient than carbogen alone for increasing hypoxic tumor pO2 in animals. If the animals data could be extrapolated to humans, then the effect of carbogen on tumor oxygenation should be increased by perflubron emulsion administration.

Administration, Inhalation↗

PubMed1998

A study of the relationship between trace element Mo and gastric cancer.

AIM:To study the relationship between trace element Mo and gastric cancer.MATERIALS AND METHODS: Soil samples were collected according to its type in different areas of Jiangxi Province; available molybdenum content in soil was measured by catalytic polarography and rank correlation method was used to analyse correlation between the mean of soil available molybdenum and mortality rate of gastric cancer in each county and city in Jiangxi Province. Gastric cancer cases were selected from the authors' hospital, occiput hair was collected to measure its molybdenum content with an atomic absorption spectrograph and controls were selected from the same hospital for comparison. Gastric cancer cases were selected from three hospitals at the same time, blood samples were taken on an empty stomach and serum molybdenum contents were measured with the atomic absorption spectrograph, and controls were selected from the same hospitals. Blind method was used in the whole course (chemical analysts did not know the source and nature of samples).RESULTS: A negative correlation existed between soil available molybdenum content and mortality rate of gastric cancer (r = -0.285, P < 0.05); hair molybdenum contents of gastric cancer cases were lower than those of healthy controls (0.308&mgr;g/g plus minus 0.673&mgr;g/g and 0.707&mgr;g/g plus minus 0.561&mgr;g/g respectively, P < 0.01); serum molybdenum contents of patients were also lower than those of healthy controls (21.84&mgr;g/L plus minus 7.49&mgr;g/L and 25.38&mgr;g/L plus minus 8.58&mgr;g/L respectively,P< 0.05).CONCLUSION: Deficiency of molybdenum may be one of the risk factors in gastric cancer.

Journal Article↗

PubMed1995

Antimony oxidation states in antileishmanial drugs.

Chemical methods specific for the determination of the levels of trivalent antimony (Sb+3) and pentavalent antimony (Sb+5) were used to investigate proprietary formulas used to treat leishmaniasis. Trivalent antimony was determined by differential pulse polarography, whereas Sb+5 was determined by iodine titration. Proprietary formulas based on N-meglumine antimoniate (Glucantime) were analyzed in detail. The results showed Sb+3 in all ampules of Glucantime. In formulations said to contain either 85 or 100 mg of Sb+5/ml, we found both forms of antimony. The amount of Sb+3 ranged from 10.5 to 15.8% (10.06-18.96 mg of Sb/ml). These findings raise issues on product stability and standardization and may help to clarify resistance to antimonial drugs and the reducing effect of tissue on Sb+5.

Antimony↗

PubMed1982

Electrochemical reduction pathways of anthracycline antibiotics.

The preparative electrochemical reduction of a series of anthracycline antibiotics was performed using the technique of large scale electrolysis and d. c. polarography for recording different reaction pathways. The reduction products were identified by mass spectrometric and chromatographic analyses. Only anthracyclines with sugar residues in the C-10 position chromatographic analyses. Only anthracyclines with sugar residues in the C-10 position (iremycin, roseorubicin A) were reduced reversibly by 2e- to the corresponding hydroquinones. All others with sugar residues in the C-7 position (daunomycin, 5-iminodaunomycin, adriamycin, carminomycin, beta-rhodomycin II, aclacinomycin A, 1-deoxypyrromycin) showed an irreversible behavior because of the reductive splitting of the glycosidic bond after formation of 7-deoxy compounds or -- if the C-11 OH-group was not present -- of dimers, respectively.

Anti-Bacterial Agents↗

PubMed1976

[Diagnosis and treatment of post-traumatic chronic venous insufficiency of the lower limbs].

The authors report 87 observations on posttraumatic chronic lymphovenous insufficiency of the lower extremities. Basic methods of examination of such patients; rheovasography, polarography, thermography, veno- and lymphography are described. Grounds are given for the complex treatment of chronic lymphovenous insufficiency after A.V. Vishnevsky and A.A. Vishnevsky technic and the procedure of fibrolysis with supra- and subfascial ligation of communicating veins.

Adult↗

PubMedDate not supplied

[Acidity and interaction with superoxide anion radical of echinochrome and its structural analogs].

Weak acid properties, autoxidation and interaction of natural polyhydroxy1,4-naphthoquinones (PHNQ) with superoxide anion-radical (O2-.) were studied by methods of potentiometric titration, polarography, and UV- and visible spectrophotometry. Sea urchin pigments 3-acetyl-2,6,7-trihydroxynaphthazarin (spinochrome C), 2,3,6,7-trihydroxynaphthazarin (spinochrome D), 2,3,6,7-trihydroxynaphthazarin (spinochrome E), 6-ethyl-2,3,7-trihydroxynaphthazarin (echinochrome A), synthetic 2,3-dihydroxy-6,7-dimethylnaphthazarin and 6-ethyl-2,3,7-trimethoxynaphthazarin (trimethoxyechinochrome A) were tested. Determined dissociation constants (pKi) were in the range of pH 5.3-8.5 (40% ethanol solvent). PHNQ autoxidation observrd in basic pH were inhibited by superoxide dismutase. Xanthine and xanthine oxidase was applied for O2-. generation. Interaction with O2-. led to sufficient time-dependent changing in spectra of echinochrome A, spinochromes D and E. There was weak O2-. influence on spinochrome C spectrum and no changing in trimethoxyechinochrome A spectrum. The spectra, that were transforming during time of reaction, contained pronounced isobestic point. It means formation the single reaction product. We proposed formation of 1,2,3,4-tetraketones from 2,3,5,8-tetrahydroxy-1,4-naphthoquinones (echinochrome A, spinochromes D and E) due to O2-.-induced oxidation of their OH-groups in 2 and 3 positions. Reaction constants were determined by competition method using nitro blue tetrazolium (NBT). The reaction constants were about 10(4)-10(5) M-1s-1. They were decreased in the order: echinochrome A > spinochrome D > spinochrome C > NBT > trimethoxyechinochrome A. Thus, we concluded that some of the natural PGNQ, containing hydroxyl groups in 2nd and 3rd positions, could operate as powerful superoxide anion-radical scavengers.

Antioxidants↗

PubMed1999

[Effect of ecological factors on levels of toxic metals--lead and cadmium--in the drugs Flos tiliae and Flos sambuci].

The method of differential pulse polarography was employed to determine the content of the toxic metals lead and cadmium in the drugs Flos tiliae and Flos sambuci collected on purpose in the course of seven years in two ecologically different localities: in "an ecologically pure environment" and in an ecologically damaged environment". The gained results are evaluated on the basis of the relationship of an increased content of the toxic metal and a locality, and particularly whether they comply with the requirements for the allowed limits proposed in the literature for the metals under study in the drugs used for pharmaceutical purposes.

Cadmium↗

PubMed1999

[The effect of streptozotocin-induced diabetes in the neonatal period on hepatic mitochondrial bioenergetics in adult rats].

BACKGROUND: Previous experimental studies focused on the liver mitochondrial bioenergetic changes in diabetes mellitus type I induced in adult animals. Information about the effects of persisting neonataly induced diabetes mellitus type I on the mitochondrial bioenergetics are missing. AIM: The aim of the study was to assess the degree of diabetes mellitus compensation and parameters of oxidative phosphorylation in rats aged 3 months with DM persisting from neonatal period. METHODS: DM was induced in male Wistar rats by repeated intraperitoneal administration of streptozotocine 45 mg/kg on 2nd and 9th day after birth. The concentrations of glucose, glycosylated haemoglobin, fructosamine were detected in the blood and the concentration of cholesterol and triacylglycerols in the blood and liver tissue, respectively. After mitochondria isolation from the liver we measured parameters of oxidative phosphorylation by polarography using Clark oxygen electrode. RESULTS: In the group of neonataly induced DM the concentration of glucose (23.10 +/- 1.55 vs 8.3 +/- 0.56 mmol/l), glycosylated haemoglobin (6.04 +/- 1.17 vs 3.99 +/- 0.44%) and blood cholesterol concentration (2.15 +/- 0.11 vs 1.83 +/- 0.09 mmol/l) increased significantly (p < 0.001 and p < 0.005 for cholesterol) comparing to a group of healthy rats. No statistically significant differences were found in the remaining parameters when comparing these two groups. The parameters of oxidative phosphorylation were significantly (p < 0.001) decreased in the group with DM comparing to control group of healthy animals--the index of respiratory control (4.87 +/- 0.25 vs 9.57 +/- 0.34), the rate of oxygen consumption in the stage 3 in ADP presence (88.61 +/- 4.62 vs 165.08 +/- 4.5 natO.mg/protein/min) and phosphorylation rate (203.54 +/- 7.26 vs 332.87 +/- 7.39 nmolATP.mg/protein/min) with NAD substrate glutamate. Similar trend was also seen with FAD substrate succinate. The index of oxidative phosphorylation ADP:0 was not changed in both groups. CONCLUSIONS: In 3 months old rats with neonataly induced DM the development of steatosis was not observed and uncoupling of oxidative processes from phosphorylation did not appear. Energy production was sufficient enough for normal functions of the liver and to ensure all needs of the organism. (Tab. 4, Ref. 51.)

Aging↗

PubMed1998

[Study on certified reference material of germanium in Ganoderma lucidum].

Analytical reference material of Ge in Ganoderma lucidum is designed and prepared for accurete analysis, monitoration and evaluation in trades of farming, forestry, medicine and food hygiene for Ge. It is used in technical training, technical assessing, monitoring, data arbitrating and analytic method verifing for professional supervisors. This reference material has been certified by graphitic oven atomic absorption spectrometry, hydride spectrophotometry, polarography, chemical separation spectrophotometry, atomic fluorescence method and x-ray fluorescence method. According to Grubb's law to judge the data of each group, it is confirmed that all of seven groups certified crude data are normal distribution by checking normality D. The arithmatic mean value of all data is 0.38 microgram/g. Standard deviation is 0.08 microgram/g.

Drugs, Chinese Herbal↗

PubMedDate not supplied

[Effect of lipid monolayers on diffusion of oxygen through the air/water interface].

The dependence of the diffusion current on the depth of immersion of the electrode was studied by polarography using an open platinum electrode. As the electrode was brought from the depth of the liquid phase to its surface, an increase in the current under aerobic conditions was observed, due to diffusion of oxygen through the interface. The formation of lipid monolayers of phosphatidylcholine, stearic acid, hexadecanol, octadecanol, eicosanol, and docosanol on the water surface led to a decrease in diffusion current; the effect being most pronounced at a minimal depth of immersion of the electrode. The maximum value of the relative decrease in diffusion current R was obtained for docosanol monolaers. It was shown that the R value increases with increasing surface pressure in monolayers of phosphatidylcholine and stearic acid. It is assumed that the decrease in diffusion flow of O2 in the presence of monolayers is caused by the formation of an energy barrier that prevents the sorption of O2, which is related to the presence of hydrocarbon chains weakly interacting with oxygen.

Air↗