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At least 649 records · Page 36Linked to original sources
PubMed1985

An improved malondialdehyde assay for estimation of thromboxane synthase activity in washed human blood platelets.

After stimulation of the washed human blood platelets by arachidonic acid (AA), the concurrent evaluations for formed malondialdehyde (MDA) measured by the common photometrical thiobarbituric acid (TBA) method, and for thromboxane B2 (TXB2) measured by gas chromatography, revealed that the formed MDA exceeded the amount of TXB2 on a molar base. However, MDA and TXB2 originating from thromboxane synthase activity should be produced in approximately equimolar amounts. By treatment of the stimulated platelet samples with stannous chloride it is possible to reduce all peroxidized products of AA which generate MDA otherwise during the TBA reaction and to estimate MDA and TXB2 in a ratio of nearly 1:1. The stannous chloride treatment does not destroy the MDA and does not influence the TBA reaction with MDA. Therefore the simple and quick TBA method can be used after stannous chloride treatment for estimation of thromboxane synthase activity in AA stimulated washed human platelets.

Arachidonic Acid↗
PubMed1996

Secretory function of adrenal chromaffin cells cultured on polypyrrole films.

Polypyrrole (PPy) is a conducting polymer and is obtained electrochemically on an electrode such as indium-tin oxide (ITO). In this study, in order to develop a novel cell-culture system which makes it possible to communicate with cultured mammalian cells, bovine adrenal chromaffin cells were cultured on PPy-coated ITO plates for 7 days and the influence of PPy-coating on the cell functions was investigated. Since the chromaffin cells synthesize and secrete catecholamines such as adrenaline and noradrenaline, the amount of synthesized and released catecholamines from the chromaffin cells cultured on PPy-coating and ITO itself were measured. The cells on the PPy-coated ITO plate could be kept in culture, without any significant changes in morphology and in the secretory responsiveness to acetylcholine as compared with those of the cells cultured on collagen. On the contrary, the cells on the ITO plate lost the responsiveness, while the amount of catecholamines synthesized was affected little by both PPy and ITO surfaces. It is suggested that PPy supports the secretory function of the chromaffin cells when they are cultured on it. This paper describes that PPy films are applicable as a polymer-modified electrode which support the cell function without collagen.

Animals↗
PubMed1996

Morphological aspects of endothelial cells cultured in the absence of fetal calf serum under controlled electrical charges applied to the support.

The effect of constant and modulated electrical charges applied through the culture support on endothelial cell (EC) morphology was investigated. Endothelial cells tolerated electrical charges for 48 hours, in a serum-free medium. The EC had normal morphology, except at high stationary charges, for which nucleus and cell size increased. The observed cell divisions and cellular secretions indicated that the cells rapidly adapted to the imposed stresses.

Cell Adhesion↗
PubMed1992

Protective effect of zinc on heme biosynthesis disturbances in rabbits after administration per os of tin.

In the present study the lowest p.o. doses of tin affecting heme biosynthesis in rabbits were determined and the protective effect of zinc on these disorders was evaluated. The experiment was performed on female rabbits who received per os single doses of SnCl2 x 2 H2O (10, 100, and 200 mg Sn/kg) and ZnSO4 (50 mg Zn/kg s.c.). The activities of delta-aminolevulinic acid dehydratase (ALA-D) in the whole blood, free erythrocyte propoporhyrins, urine delta-aminolevulinic acid, and coproporphyrins (CP-U) were determined. In animals administered tin at a dose of 100 mg Sn/kg, ALA-D activity decreased by about 80% and two- to threefold increases in the ALA and CP concentrations in urine were observed. A protective effect of zinc with respect to ALA-D activity was noticed in both groups (100 and 200 mg Sn/kg) after combined administration of both metals. Results of an interaction between zinc and tin were also observed to reduce ALA levels in urine, whereas zinc did not protect against an effect of tin on CP excretion.

Administration, Oral↗
PubMedDate not supplied

Transparent indium-tin oxide electrode patterns for extracellular, multisite recording in neuronal cultures.

Glass plates coated with transparent thin film conductors of indium-tin oxide (ITO), 100 nm thick and 10 microns wide, have been successfully used to record spike potentials from neuronal monolayer cultures. The material is non-toxic to mammalian spinal neurons and is stable under warm culture medium. Laser-deinsulated recording craters that expose 100 mu m2 of ITO yield impedances of 8-10 M omega at 1 kHz with noise levels of 40 muV. Conventional gold plating of the craters reduces these impedances to below 3 M omega. The material is easily etchable and sputtered glass plates of high quality are commercially available at relatively low cost. The high light transmittance of ITO makes the conductors essentially invisible and allows unobstructed observation of circuit components in monolayer cultures. The introduction of ITO as a thin film microelectrode material should accelerate the construction of high density recording patterns that could exceed 400 microelectrodes per mm2.

Action Potentials↗
PubMed1993

Stimulation of monolayer networks in culture through thin-film indium-tin oxide recording electrodes.

Monolayer networks, obtained from murine spinal cord tissue and grown on a matrix of 64 photo-etched, indium-tin oxide (ITO) microelectrodes, can be electrically stimulated through such thin-film recording electrodes. Multichannel coordinated network activity can be evoked and spontaneous network activity can be modified by generation of additional, multichannel bursting. Although single pulses through 1 electrode may trigger network responses, networks generally react best to short trains of pulses. Response thresholds approximate standard physiological strength/duration relationships. Repetitive stimulation trains often generate network activity patterns akin to epileptiform activity. The ITO conductors remain stable for recording under warm saline for long periods of time (maximum test period: 8 months). However, most electrodes show a reduction in impedance after several thousand stimulus pulses. Electrode breakdown in the form of ITO oxidation and loss of light transmittance occurs before hydrolysis is observed but requires a combination of voltage levels and pulse lengths beyond that needed for effective network stimulation.

Animals↗
PubMed1994

Evaluation of potential genotoxicity of stannous chloride: inactivation, filamentation and lysogenic induction of Escherichia coli.

Because of the importance of stannous chloride in various fields of human endeavour, the potential genotoxicity of this reducing agent was evaluated by measurement of either the inactivation or the induction of SOS responses in bacteria. Escherichia coli strains used in this work (wild type, uvrA, recA, lexA and uvrA recA) were treated with stannous chloride; the wild type was found to be the most resistant and the double mutant, the most sensitive strain. As these strains present mutations on specific genes for the repair of DNA, stannous chloride would appear to be capable of inducing and/or producing lesions in DNA and, thus, can be considered to be a potential genotoxic agent. This capability was confirmed by the lysogenic induction of E. coli K12 (lambda) (Inductest) and by microscopic observation of E. coli B filamentation.

DNA Repair↗
PubMed1980

Dose-effect of inorganic tin on biochemical indices in rats.

The dose-effect of stannous chloride on biochemical indices was examined in weanling male rats given oral doses of 0.3, 1.0 and 2.0 mg/kg at 12-h intervals for 90 days. The 3.0 mg/kg dose caused significant decreases of the relative weights of the femur, calcium concentration, lactic dehydrogenase and alkaline phosphatase activities in the serum, succinate dehydrogenase activity in the liver, and calcium content and acid phosphatase activity in the femoral diaphysis and epiphysis. Of the above indices, the 1.0 mg/kg dose produced significant reduction of succinate dehydrogenase activity in the liver, and calcium content and acid phosphatase activity in the femoral epiphysis. Those significant decreases were not observed with the 0.3 mg/kg dose, although a slight but not significant decrease of calcium content in the femoral epiphysis was observed. These results suggest that the no-effect level of inorganic tin orally administered would be lower than 0.6 mg/kg/day.

Alkaline Phosphatase↗
PubMed1992

The effect of tributyltin chloride on vascular responses to atrial natriuretic peptide.

The effects of tributylin chloride (TBT) on vascular smooth muscle responses to norepinephrine, nitroprusside (SNP) and atrial natriuretic peptide (ANP) were studied in isolated aortic rings of rats. TBT did not interfere with norepinephrine-induced contraction or SNP-induced vasorelaxation. However, TBT produced a dose-dependent inhibition of ANP-induced vasorelaxation. Inhibition was not observed with inorganic tin chloride, SnCl2. The inhibition of vasorelaxation was accompanied by a parallel inhibition of ANP-induced cGMP generation. SNP-induced generation of cGMP was not affected by TBT. TBT did not interfere with binding of ANP to its receptor in bovine adrenal glands suggesting that the effects of TBT were mediated by direct interaction with membrane-bound guanylate cyclase.

Animals↗
PubMedDate not supplied

Water absorption of (RTV) silicone denture soft lining material.

OBJECTIVES: The reason for high water absorption by room temperature vulcanizing (RTV) silicone denture soft lining materials has not been demonstrated previously. An experimental room-temperature vulcanizing (RTV) silicone soft lining material which had been shown to have good mechanical properties had high water absorption at equilibrium whilst losing only small amounts of soluble material after desorption. The volume change in the material was also high. A variety of formulations of the experimental material was devised in order to determine the cause of the high water sorption values. METHODS: Water sorption values were determined using standard experimental techniques. Sections of the polymerized materials were examined by scanning electron microscopy for microporosity. RESULTS: Neither removal of residual cross-linker nor changing the method of polymerization reduced the water absorption. Scanning electron microscopy did not demonstrate a porous structure of the polymerized material. A correlation was seen between filler content and water absorption. A formulation without filler showed a greatly reduced water absorption and volume change. CONCLUSION: It was concluded that the filler was directly responsible for the water absorption of the RTV material.

Absorption↗
PubMed1981

Contrast effects in photoelectron microscopy; UV dose-dependent quantum yields of biological surface components.

The relative brightness of photoelectron microscopy images as a function of exposure to UV light has been determined from model systems representative of biological cell surface components. Quantitative data for amino acid homopolymers, yields. The photoelectron quantum yields, increase substantially over the initial values. For example, the quantum yields fo poly-L-tyrosine at 200 nm is initially about 5 X 10(-8) electron/incident photon. The quantum yield increases with 254 nm irradiation, leveling off at about 5 X 10(-4) electrons/incident photon after a dose of 3 X 10(21) quanta cm-2. Pre-irradiation of poly-L-tyrosine in the presence of certain chemical agents, for example, the Lewis base diborane (B2H6), results in a substantial reduction of the dose-dependent increase in quantum yield. Exposure to the reducing agent stannane (SnH4) essentially eliminates the effect. These chemical treatments provide methods of controlling the UV dose-dependent effects in the photoelectron images.

Amino Acids↗
PubMed1981

Inorganic tin in the diet affects the femur in rats.

The effects of dietary levels (10, 50, 100 and 250 ppm tin) of stannous chloride on the femur were studied for 90 days on weanling male rats. The 100 and 250 ppm tin (Sn) caused significant decreases in serum calcium (Ca) and serum inorganic phosphorus (P), Ca content in the femoral diaphysis and epiphysis, and acid phosphatase activity in the femoral epiphysis. 50 ppm Sn produced significant reduction of serum Ca concentration and Ca content in the femoral epiphysis. These significant decreases were not observed with 10 ppm Sn. These results suggest that the maximal allowable concentration of inorganic Sn contained in a diet would be less than 50 ppm Sn.

Acid Phosphatase↗
PubMed1983

Inhibition of hepatic azo-reductase and aromatic hydroxylase by radiopharmaceuticals containing tin.

Mice given single i.v. doses of some radiopharmaceuticals containing stannous chloride as a reducing agent, showed significant inhibition of hepatic azo-reductase and aromatic hydroxylase activity at dose levels which contained as little as 0.2 mg/kg of stannous chloride. Cytochrome P-450 content was also reduced significantly. Some of the above radiopharmaceuticals would have to be injected at approx. 10 times the maximum recommended human dose to reach a 0.2 mg/kg dose level of stannous chloride in man, provided other sources of stannous ion were excluded.

Aniline Hydroxylase↗
PubMed1984

The effects of stannous chloride on the humoral immune response of mice.

The effects of stannous chloride (SnCl2) on primary and secondary immune responses to sheep red blood cells (SRBCs) were examined in mice. I.p. administration of 167 mumol/kg/day of SnCl2 for 3 consecutive days suppressed the number of splenic indirect plaque-forming cells (PFCs) in the primary response and the hemagglutination (HA) and hemolytic reaction (HR) titers of non-2-mercaptoethanol(2-ME)-treated sera in both the primary and secondary immune response. However, tin affected neither the indirect PFC response nor the antibody titers of the 2-ME-treated sera after the secondary immunization, which was performed on day 6 following the primary immunization. These results suggest that the subacute administration of tin suppresses part of the immune response in which IgM antibody production plays an important role, and that the production of IgG in the secondary immune response is little affected, while the IgG production in the primary response is suppressed or delayed.

Animals↗
PubMed1986

Dose-dependent brain tin concentration in rats given stannous chloride in drinking water.

Male Wistar rats were given either 100 mg SnCl2 X 2H2O per litre (0.44 mM), 250 mg/l (1.11 mM) or 500 mg/l (2.22 mM) in their drinking water for 1-18 weeks. Tin detected by a novel atomic absorption spectrophotometric method accumulated in the cerebrum at the highest dose level (2.22 mM) throughout the experiment. In brain, tin concentrations above the 1.11-mM dose were only found after 15 and 18 weeks. Tin did not increase in the brain at the 0.44-mM dose level. Blood tin increased promptly after one week at the highest dose (2.22 mM) without further accumulation. Blood tin at the 0.44 mM dose level did not differ from controls. Tin exposure caused a dose-dependent increase in the cerebral and muscle acetylcholinesterase activity at the two higher doses.

Acetylcholinesterase↗
PubMed1987

Preparation and evaluation of a hydrous tin(IV) oxide 82Sr/82Rb medical generator system for continuous elution.

Hydrous tin(IV) dioxide in the Na+-form appears to be the most efficient inorganic exchanger for a reliable and versatile clinical 82Rb generator. Continuous elution with a commercial physiological NaCl solution yields 82Rb ranging between 10 and 40% at a flow rate as low as 3 to 10 mL/min respectively. At the same time the Sr breakthrough is less than 1.6 10(-6)%/mL. A clinical generator loaded with 100 mCi 82Sr (150 mCi 85Sr) and continuously eluted for 3 min at a typical flow rate of 5 mL/min yields 40 mCi of 82Rb, 8 nCi of 82Sr and 11 nCi of 85Sr. The total absorbed radiation dose for 40 mCi 82Rb administered is primarily due to 82Rb and has been estimated for the three principal target organs as 760 mrad for the kidneys, 520 mrad for the heartwalls and 276 mrad for the lungs. The 82,85Sr contribution to the dosimetry has been shown to be negligible. The absence of radiolysis with generators loaded with high level of 82Sr was demonstrated by the excellent reproductibility of continuous elution properties of the generator during its practical shelf-life estimated to 5-6 weeks of clinical use which would require more than 30 L of eluent.

Humans↗
PubMed1992

Evaluation of reduction-mediated labelling of antibodies with technetium-99m.

Monoclonal antibodies can be labelled with technetium-99m by prereduction of the antibody with 2-mercaptoethanol, then reduction of pertechnetate with an aliquot of a stannous kit, resulting in greater than 97% labelling without the need for further purification. The present work shows that equally high labelling can be obtained with a variety of weak ligands and that the optimum quantity of stannous chloride is 2-4 micrograms. Although the label was stable to challenge with excess DTPA, cysteine was able to remove a portion of the label. We have also shown that this technique works with the IgG2a isotype in addition to the previously reported IgG1 isotype. This approach is simple, convenient and reproducible, and warrants further clinical evaluation.

Antibodies, Monoclonal↗
PubMed1992

Evaluation of the 111In-(Sn)-citrate method to label antibodies for radioimmunotargeting studies.

Monoclonal antibody against carcinoembryonic antigen (CEA) was labeled by the 111In-(Sn)-citrate technique and its characteristics were determined from the point of radioimmunotargeting studies. Antibodies of high specific radioactivity could be labeled with a high labeling yield of greater than 90% without any further purification step, and without loss of immunoreactivity. In biodistribution studies using nude mice bearing CEA-producing tumors, an extremely high tumor-to-blood ratio (40 on day 6) was obtained since 111In in the blood cleared very rapidly, but nonspecific 111In localized in the liver and spleen should be seriously considered.

Animals↗