Stannosis: benign pneumoconiosis due to tin dioxide.
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Heavy Metal Poisoning↗
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Interaction of Et2SnCl2 with 5'-IMP and 5'-GMP.
The interactions of Et2SnCl2 with 5'-IMP and 5'-GMP have been studied in aqueous solutions by 1H- and 31P-NMR spectroscopy as a function of pH. At low pH values (< 4.0) Sn(IV) interacts with the pyrophosphate oxygens of these nucleotides. At intermediate pH values (4-9.5) no interaction of the metal with the nucleotides take place, while at pH > 9.5 the sugar O'2 and O'3 atoms are the preferred coordination sites. In addition, the solid adducts obtained from aqueous solutions at pH = 3-4 of the above interactions correspond to formulae; (Et2Sn)2(5'-IMP)2(H2O) and (Et2Sn)3(5'-GMP)2(OH)2(H2O)2 as their elemental analysis show. IR spectra and solid state 13C, 31P-NMR spectra 119Sn Mössbauer and solution 119Sn-NMR spectra once more confirm the pyrophosphate involvement in bonding with Sn(IV) in oligomeric or polymeric structures and trigonal bipyramidal or octahedral geometries.
Guanosine Monophosphate↗
Measurement of charge transfer during bacterial adhesion to an indium tin oxide surface in a parallel plate flow chamber.
An experimental method is described for the measurement of charge transfer during bacterial adhesion in situ to a transparent, semiconducting indium tin oxide (ITO) coated glass plate in a parallel plate flow chamber. Bacterial adhesion is measured simultaneously with either the electric potential or the capacitance of the surface. Initial bacterial adhesion was accompanied by a change in electric potential of the surface with no measurable change in capacitance. Consequently, it can be assumed that the change in electric potential of the surface is due to charge transfer between bacteria and the surface, and it can be calculated that, on average, a charge of about 10(-14) C per bacterium is exchanged during initial adhesion, which corresponds to only several percent of the total surface charge of a bacterium. Charge transfer could either be to or from the bacterial cell surface, dependent on the bacterial strain involved and the ionic strength used.
Actinomyces↗
[No influence of propanolol, cyclosporine, adriamycin, and nifedipine on the in vitro labelling of erythrocytes].
UNLABELLED: The objective of this work was to study the potential interference of propanolol, cyclosporine, adriamycin, and nifedipine with the in vitro labelling of erythrocytes. MATERIALS AND METHODS: 20-ml blood specimens were collected from 40 healthy volunteers who had not taken any drug in the week before collection. 2.0-ml alliquots were incubated at 37 C with different concentrations of the drugs for 30 minutes. In all cases, a control group was incubated with saline (0.9%). Two labelling methods were used: 1) EDTA method, in which 60 l of SnCl2 (10.2 g/ml), 2.0 ml of saline, 0.2 ml EDTA 2.2%, and 7.4 MBq of Na99mTcO4 were added, and the mix was incubated for 5 minutes. 2) The hypochlorite method, in which specimens were initially incubated with SnCl2 (10.2 g/ml) for 5 minutes. Then, 40 l of 1% hypochlorite and all the reagents described in the previous method were added. With both methods, erythrocytes were separated by centrifugation and the labelling yield was estimated. RESULTS: RESULTS did not show significant differences between the yield of the control group labelling and the yield of the different concentrations of the tested drugs. Also, significant differences were not observed the two labelling methods used. CONCLUSION: Both labelling methods are useful for the in vitro preparation of 99mTc-erythrocytes. The absence of significant differences in the labelling yield indicates that in vitro interferences observed by some investigators are associated with concentrations exceeding therapeutic plasma levels. On the other hand, the reported in vivo interferences might be due to the presence of active catabolites and/or interference between different drugs.
Adult↗
[Labeling of leukocytes using stannous 99mTc-colloid in whole blood samples].
This paper presents the preparation of a radiocolloid that still makes it possible to label leukocytes using its phagocytosis capacity. Given that this function is exclusively of the white blood cells, not being exercised by other blood cells, the use of a stannous fluoride radiocolloid labeled with 99mTc (F2Sn-99mTc) was tested in order to label leukocytes in whole blood samples. Using cellular separation techniques in density gradients and acquisition of images in gamma camera of radioactivity distribution in Percol, it was observed that the white cells labeling achieved was selective and with high efficiency for leukocytes (in all cases, it was superior to 70%), optimal reproducibility, low cost and low cellular toxicity.
Humans↗
Genotoxic effects of stannous chloride (SnCl2) in K562 cell line.
The toxic effects of SnCl2 in K562 cells were analyzed in this study. This cell line is resistant to reactive oxygen species (ROS) making it suitable to evaluate the impact of SnCl2 in culture either through ROS or by direct toxicity using Trypan blue dye exclusion, comet and flow cytometry assays. An important loss of viability induced by SnCl2 in a dose-response manner was observed in cells treated in Tris-buffered saline (TBS). This necrotic cell death was further confirmed by flow cytometry. On the other hand, there was no loss of viability when cells were treated in rich medium (RPMI). DNA damage was visualized in SnCl2-treated K562 cells in both tested conditions. The data indicate that SnCl2 induces DNA damage and reduces K562 viability. Both actions seem to be correlated with ROS formation and direct linkage to DNA.
Cell Survival↗
Assessment of the effect of Fucus vesiculosus extract on the labeling of blood constituents with technetium-99m and the histological modifications on the shape of the red blood cells.
Natural products are widely used as food or food additives or medicines for humans. We are trying to develop a model to assess the possible toxic properties of natural products, such as Fucus vesiculosus, utilized in popular medicine. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used in various procedures in nuclear medicine. This labeling procedure depends on a reducing agent, and stannous chloride is used. There is evidence that this labeling may be altered by drugs. We have investigated the possibility that F. vesiculosus extract is capable of altering the labeling of blood elements with 99mTc. Blood was incubated with F. vesiculosus extract and stannous chloride solution and Tc-99m added. Blood was centrifuged and plasma (P) and blood cells (BC) were isolated. Samples of P or BC were also precipitated, centrifuged and insoluble (IF) and soluble (SF) were separated. The percentages of radioativity (%ATI) in BC, IF-P and IF-BC were calculated. Histological preparations of the RBC treated with F. vesiculosus revealed that this extract is capable of promoting important modifications on the shape of the RBC. The%ATI decreased on BC from 93.6+/-2.3 to 29.0+/-2.7, on IF-P from 77.6+/-1.2 to 7.5+/-1.0 and on IF-BC from 80.0+/-3.4 to 12.6+/-4.8. Once the RBC labeling procedure with 99mTc depends on the presence of stannous (+2) ions, the substances present in the F. vesiculosus extract should increase the valence of these ions to stannic (+4). This would decrease the%ATI on blood elements and indicate the presence of oxidant agents in the F. vesiculosus extract.
Animals↗
Comparative assessment of gastrointestinal irritant potency in man of tin(II) chloride and tin migrated from packaging.
Tin is present in low concentrations in most canned foods and beverages, the highest levels being found in products packaged in unlacquered or partially lacquered tinplate cans. A limited number of case-reports of acute gastrointestinal disorders after consumption of food containing 100-500 mg/kg tin have been reported, but these reports suffer many insufficiencies. Controlled clinical studies on acute effects of tin migrated from packaging suggest a threshold concentration for adverse effects (AEs) of >730 mg/kg. Two separate randomised, single-centre, double-blind, crossover studies, enabling comparison of the tolerability of tin added as tin(II) chloride at concentrations of <0.5, 161, 264 and 529 mg/kg in 250 ml tomato juice in 20 volunteers (Study 1) and tin migrated from packaging at concentrations of <0.5, 201 and 267 mg/kg in 250 ml tomato soup in 24 volunteers (Study 2) were carried out. Distribution studies were conducted to get insight in the acute AEs of low molecular weight (<1000 Da) tin species in the soluble fraction of food products. Results show that the chemical form of tin and not the elemental concentration per se determines the severity of AEs. A clear dose-response relationship was only observed when tin was added as tin(II) chloride in tomato juice. No clinically significant AEs were reported in Study 2 and comparison of the incidence of tin-related AEs showed no difference between the dose levels (including control). Tin species of low molecular weight in supernatant represented 31-32% of total tin in canned tomato soup versus 56-61% in juice freshly spiked with tin(II) chloride. Differences in the incidence of AEs following administration of tomato juice with 161 and 264 mg of tin per kg and tomato soup with 201 and 267 mg of tin per kg likely results from differences in the concentration of low molecular weight tin species and in the nature of tin complexes formed. The results of this work demonstrate that tin levels up to 267 mg/kg in canned food cause no AEs in healthy adults and support the currently proposed tin levels of 200 mg/kg and 250 mg/kg for canned beverages and canned foods, respectively, as safe levels for adults in the general population.
Adolescent↗
Lethality induced by stannous chloride on Escherichia coli AB1157: participation of reactive oxygen species.
Stannous chloride (SnCl2) has been widely used in nuclear medicine as a reducing agent of pharmaceutical products radiolabelled with technetium-99m. To verify whether the lethality induced by this salt could be mediated by reactive oxygen species (ROS), Escherichia coli cultures were treated with SnCl2 in the presence of catalase, ROS scavengers or metal-ion chelators. The inactivation effect, as measured by survival determination, was abolished by thiourea, sodium benzoate, dipyridyl or catalase. The results suggest the participation of ROS, generated by a Fenton-like reaction, in the lethal effect induced by SnCl2.
2,2'-Dipyridyl↗
Shark cartilage-containing preparation: protection against reactive oxygen species.
There is overwhelming evidence to indicate that free radicals cause oxidative damage to lipids, proteins and nucleic acids and are involved in the pathogenesis of several degenerative diseases. Therefore, antioxidants, which can neutralize free radicals, may be of central importance in the prevention of these disease states. The protection that fruits and vegetables provide against disease has been attributed to the various antioxidants contained in them. Recently, an anti-inflammatory and analgesic activity of a water-soluble fraction from shark cartilage has been described. Using electrophoretical assays, bacteria survival and transformation and the Salmonella/mammalian-microsome assay, we investigated the putative role of shark cartilage-containing preparation in protecting cells against reactive oxygen species induced DNA damage and mutagenesis. If antimutagens are to have any impact on human disease, it is essential that they are specifically directed against the most common mutagens in daily life. Our data suggest that shark cartilage-containing preparation can play a scavenger role for reactive oxygen species and protects cells against inactivation and mutagenesis.
4-Nitroquinoline-1-oxide↗
Adaptive response to H(2)O(2) protects against SnCl(2) damage: the OxyR system involvement.
The stannous ion, mainly the stannous chloride (SnCl(2)) salt form, is widely used as a reducing agent to label radiotracers with technetium-99m ((99m)Tc). These radiotracers can be employed as radiopharmaceuticals in nuclear medicine procedures. In this case, there is no doubt about absorption of this complex, because it is intravenously administered in humans, although biological effects of these agents have not been fully understood. In this work we used a bacterial system to study the cytotoxic potential of stannous chloride. It is known that SnCl(2) induces lesions that could be mediated by reactive oxygen species (ROS). We, thus, investigated the existence of cross-adaptive response between hydrogen peroxide (H(2)O(2)) and SnCl(2) and the role of the OxyR system known to promote cellular protection against oxidative damages. Here we describe the results obtained with prior treatment of different Escherichia coli strains with sub-lethal doses of H(2)O(2), followed by incubation with SnCl(2). Our data show that H(2)O(2) is capable of inducing cross-adaptive response against the lethality promoted by SnCl(2), suggesting the OxyR system participation through catalase, alkyl hydroperoxide reductase and superoxide dismutase enzymes
Adaptation, Biological↗
Stannous chloride and the glucoheptonic acid effect: study of a kit used in nuclear medicine.
Stannous dichloride is used as a reducing agent in the preparation of technetium-99m radiopharmaceuticals. We decided to evaluate the genotoxic potential of the tin (II)-glucoheptonate complex in the kit using a tester strain of Escherichia coli AB1157. Our results show that tin (II) chloride and the tin (II)-glucoheptonate complex exert a genotoxic effect in this system. While the genotoxic effect disappeared when the glucoheptonate concentration was increased, the glucoheptonate did not protect the cultures from the damaging effects of hydrogen peroxide. The ability of glucoheptonate to protect cultures from tin (II)-induced damage can be explained on the basis of its metal chelating properties.
Escherichia coli↗
Biological effects of stannous chloride, a substance that can produce stimulation or depression of the central nervous system.
It was demonstrated that tin, as stannous chloride (SnCl(2)), can facilitate the neuromuscular transmission by accelerating the transmitter release from the nerve terminals in the mouse. When this salt is injected into laboratory animals, it can produce stimulation or depression of the central nervous system. Because calcium (Ca(2+)) influx into the cytoplasm is indispensable to release the transmitter, it would be possible that SnCl(2) increases the Ca(2+) influx at the nerve terminals but not by blocking the K(+) channels. SnCl(2) is known to inhibit the immune response in rodents and to induce tumor generation in thyroid gland. There is no general agreement regarding its genotoxicity and it was discussed that the effects of this salt might depend on the physicochemical conditions and the route of its administration. SnCl(2) has been used in many sectors of human interest, such as food industry and nuclear medicine. This salt is directly administered to human beings endovenously, when it is used as a reducing agent to prepare 99mTc-radiopharmaceuticals which are also used for cerebral studies. SnCl(2) is capable to promote the generation of reactive oxygen species (ROS) that are responsible for the oxidative stress. Oxidative stress has been related with aging and other neurological diseases. So, it is relevant to evaluate other biological effects of SnCl(2). We decided to study these effects using Escherichia coli mutant strains, deficient in DNA repair genes, and supercoiled plasmid DNA. We evaluated the influence of medicinal plants, metal chelating agents, and ROS scavengers against the SnCl(2) deleterious effects. Our results show that SnCl(2) produced lesions in vitro as well as in vivo. This inactivation may be due to the production of ROS. We observed that the genotoxic effect of SnCl(2) was partly inhibited or disappeared, when the treatments were done in the presence of medicinal plants, metal chelating agents, and ROS scavengers. In conclusion, these findings suggest that the SnCl(2) biological effects may be associated with the generation of ROS. Moreover, we can speculate that ROS could be associated with the detrimental effects in the brain due to exogenous or endogenous metals.
Animals↗
Damage induced by stannous chloride in plasmid DNA.
Stannous chloride (SnCl(2)) is widely used in daily human life, for example, to conserve soft drinks, in food manufacturing and biocidal preparations. In nuclear medicine, stannous chloride is used as a reducing agent of Technetium-99m, a radionuclide used to label different cells and molecules. In spite of this, stannous chloride is able to generate reactive oxygen species (ROS) which can damage DNA. In this work, plasmid DNA (pUC 9.1) was incubated with SnCl(2) under different conditions and the results analyzed through DNA migration in agarose gel electrophoresis. Our data reinforce the powerful damaging effect induced by stannous ion and suggest that this salt can play a direct role in inducing DNA lesions.
DNA↗
Cellular inactivation induced by a radiopharmaceutical kit: role of stannous chloride.
Stannous chloride (SnCl2) has been used in many sectors of human activities such as food manufacturing and in nuclear medicine to produce radiopharmaceuticals labeled with technetium-99m (99mTc). Due to its importance and genotoxic potentiality, we decided to evaluate the biological effect induced by a nuclear medicine kit, which includes SnCl2, in association with glucoheptonic acid (GHA) which is employed for brain and renal scintigraphies. These studies were carried out with the Escherichia coli AB1157 strain and the deoxyribonucleic acid (DNA) plasmid pUC 9.1. The experiments, with different concentrations of SnCl2 and GHA, show an inverse relationship between both agents. When the GHA concentration was increased, the cellular inactivation induced by SnCl2 was reduced, as measured by the number of viable cells. Moreover, GHA protects the DNA molecule against the damage induced by SnCl2.
DNA Damage↗
Stannous chloride mediates single strand breaks in plasmid DNA through reactive oxygen species formation.
Stannous ion (Sn) has been employed in nuclear medicine and in food industry. We described that Stannous Chloride (SnCl2) inactivation effect in Escherichia coli is mediated by a Fenton-like reaction. The effect of SnCl2 was studied through: (i) the alteration of plasmid topology in neutral and acidic pH by gel electrophoresis; and (ii) the transformation efficiency of an wild type E. coli strain. Treatment of plasmid DNA pUC 9.1 with SnCl2, at pH 7.4, results in DNA single-strand breaks (SSB), in a dose-dependent manner. Addition of sodium benzoate partly inhibited the DNA damage, while EDTA completely abolishes DNA-SSB. Furthermore, the ability of the plasmid to transform E. coli was reduced. At pH 1.3, SnCl2 exerts a protective effect on plasmid against HCI depurination. Our results suggest the generation of ROS, such as *OH by a Fenton-like reaction, close to the site of the lesions due to a possible complexation of stannous ion to DNA.
DNA Damage↗
Investigation on process parameters involved in preparation of poly-DL-lactide-poly(ethylene glycol) microspheres containing Leptospira Interrogans antigens.
Block copolymer, poly-DL-lactide-poly(ethylene glycol) (PELA) with 11.5% of poly(ethylene glycol) (PEG) content was prepared by bulk ring-opening polymerization using stannous chloride as initiator. PELA microspheres with entrapped Leptospira Interrogans antigens, outer membrane protein (OMP) were elaborated by solvent extraction method based on the formation of multiple w/o/w emulsion, and the resulting microspheres were characterized with respect to particle size, OMP entrapment and morphology characteristics. The purpose of the present study is to perform the optimization of preparative parameters for OMP-loaded PELA micropsheres to control particle size and improve the OMP encapsulation efficiency. Of all the parameters investigated, the polymer concentration of organic phase and the external aqueous phase volume play major roles on particle size, while the organic phase volume, internal aqueous phase volume and the addition of surfactant into the internal aqueous phase display considerable effects on OMP loading efficiency. A small volume of internal aqueous phase and intermediate volumes of organic phase and external aqueous phase were favorable to achieve micropsheres with a size of 1-2 microns and high antigen encapsulation efficiency (70-80%). In vitro OMP release profiles from PELA microspheres consist of a small burst release followed by a gradual release phase. The OMP release rate shows some relations with the porous and water-swollen inner structure of the microspheres matrix. The presence of surfactant in microspheres accelerates OMP release, but the OMP entrapment within microspheres shows limited effects on the release profile.
Antigens, Bacterial↗
Assessment of the effect of Maytenus ilicifolia (espinheira santa) extract on the labeling of red blood cells and plasma proteins with technetium-99m.
We are trying to develop a model to assess properties of products utilized in popular medicine. Maytenus ilicifolia is used in herbal medicine. Red blood cells (RBC) labeled with technetium-99m (99mTc) are employed in nuclear medicine. This labeling procedure depends on a reducing agent and stannous chloride is used. There is evidence that this labeling may be altered by drugs. We have investigated the possibility of M. ilicifolia extract being capable to alter the labeling of blood elements with 99mTc. Blood was incubated with M. ilicifolia extract. Stannous chloride solution and Tc-99m were added. Blood was centrifuged and plasma (P) and blood cells (C) were isolated. Samples of P or C were also precipitated, centrifuged and insoluble (IF) and soluble (SF) were separated. The percentages of radioactivity (%ATI) in C, IF-P and IF-C was calculated. The %ATI decreased on C from 93.6+/-2.3 to 29.0+/-2.7, on IF-P from 77.6+/-1.2 to 7.5+/-1.0 and on IF-C from 80.0+/-3.4 to 12.6+/-4.8. Once in RBC labeling procedure with 99mTc depends on the presence of stannous (+2) ions, the substances of the M. ilicifolia extract could increase the valence these ions to stannic (+4). This fact would decrease the %ATI on blood elements and indicate the presence of oxidant agents in the M. ilicifolia extract.
Blood Proteins↗