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PubMed2004

The effect of surface chemistry and nanotopography of titanium nitride (TiN) films on primary hippocampal neurones.

The cell-substrate interaction of primary hippocampal neurones with thin films of TiN was studied in vitro. TiN films of different surface chemistries and topographies were deposited by pulsed DC reactive magnetron sputtering and closed field unbalanced magnetron sputter ion plating by Teer Coatings Ltd., Hartlebury, UK to result in TiN films with similar surface chemistries but different topographical features. TiN films were characterised using X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. The neuron-substrate interaction was examined using environmental scanning electron microscopy (FEG-ESEM) for morphological information. Bromodeoxyuridine and TUNEL assays were used to identify proliferating neurones as well as apoptotic neurones. Fluorescent staining for MAP-2 was used to label neuronal network formation. Primary hippocampal neurones were found to attach and spread to all of the TiN film chemistries and topographies investigated. Neuronal network morphology appeared to be more preferential on the nitrogen rich TiN films and also with reduced nanotopographical features.

Animals↗
PubMed2004

A tin-complexation strategy for use with diverse acylation methods in the preparation of 1,9-diacyldipyrromethanes.

The acylation of dipyrromethanes to form 1,9-diacyldipyrromethanes is an essential step in the rational synthesis of porphyrins. Although several methods for acylation are available, purification is difficult because 1,9-diacyldipyrromethanes typically streak extensively upon chromatography and give amorphous powders upon attempted crystallization. A solution to this problem has been achieved by reacting the 1,9-diacyldipyrromethane with Bu(2)SnCl(2) to give the corresponding dibutyl(5,10-dihydrodipyrrinato)tin(IV) complex. The reaction is selective for dipyrromethanes that bear acyl groups at both the 1- and 9-positions but otherwise is quite tolerant of diverse substituents. The diacyldipyrromethane-tin complexes are stable to air and water, are highly soluble in common organic solvents, crystallize readily, and chromatograph without streaking. Four methods (Friedel-Crafts, Grignard, Vilsmeier, benzoxathiolium salt) were examined for the direct 1,9-diacylation of a dipyrromethane or the 9-acylation of a 1-acyldipyrromethane. In each case, treatment of the crude reaction mixture with Bu(2)SnCl(2) and TEA at room temperature enabled facile isolation of multigram quantities of the 1,9-diacyldipyrromethane-tin complex. The diacyldipyrromethane-tin complexes could be decomplexed with TFA in nearly quantitative yield. Alternatively, use of a diacyldipyrromethane-tin complex in a porphyrin-forming reaction (reduction with NaBH(4), acid-catalyzed condensation with a dipyrromethane, DDQ oxidation) afforded the desired free base porphyrin in yield comparable to that obtained from the uncomplexed diacyldipyrromethane. The acylation/tin-complexation strategy has been applied to a bis(dipyrromethane) and a porphyrin-dipyrromethane. In summary, the tin-complexation strategy has broad scope, is compatible with diverse acylation methods, and greatly facilitates access to 1,9-diacyldipyrromethanes.

Acylation↗
PubMed1997

Palladium-Catalyzed Stille Couplings with Fluorous Tin Reactants.

A new class of "fluorous" aryl tin reactants was investigated for use in the Stille coupling. Fluorous compounds partition into a fluorocarbon (fluorous) phase in a fluorous/organic extraction. The coupling of tris[(perfluorohexyl)ethyl]phenyl tin [(C(6)F(13)CH(2)CH(2))(3)SnPh] with bromobenzene occurs smoothly in DMF/THF (1/1) at 80 degrees C in the presence of a catalytic amount of PdCl(2)(PPh(3))(2) and 3 equiv of LiCl. Partitioning between CH(2)Cl(2) and FC-72 (a mixture of perfluorohexanes) provided biphenyl in 90% yield from the organic phase and tris[(perfluorohexyl)ethyl]tin chloride in >90% yield from the fluorous phase. The tin chloride was reacted with phenylmagnesium bromide to regenerate the starting tin reactant. A study to optimize reaction conditions is described, and the scope of the method is illustrated with 20 coupling reactions. The beneficial effect of lithium choride is an unusual feature of the reaction, but it also promotes the formation of some fluoroalkyl-coupled products. These can be suppressed by adding CuI. The paper describes a prototypical example of how to render a tin reactant fluorous. This process should be advantageous in small- and large-scale synthesis, as well as in automated synthesis.

Journal Article↗
PubMedDate not supplied

Trace metal levels in the raw and tinned squid Loligo patagonica.

The cadmium, silver, lead, copper, zinc, manganese, iron and mercury levels in the edible and inedible tissues of raw and tinned Loligo patagonica squid were determined using flame atomic absorption spectrometry (AAS) for Cd, Ag, Pb, Cu, Zn, Mn and Fe and cold-vapour AAS for Hg. The mean values obtained relative to the wet-weight (mg/kg) for the edible parts (skinless mantle, arms and crone and fin) of the raw and tinned (mantle) squid, and in whole raw and tinned squid, were: 0.32, 0.32, 0.31, 4.3, 3.2 and 3.0 for Cd, 1.0, 0.34, 0.77, 0.27, 0.59 and 0.44 for Pb, 7.8, 5.5, 11, 33, 22 and 26 for Cu, 12, 13, 12, 19, 16 and 17 for Zn, 0.38, 0.45, 0.48, 0.75, 0.48 and 0.73 for Mn and 2.7, 2.3, 3.4, 3.4, 2.2 and 9.4 for Fe, respectively. The content of silver and mercury in the mantle of the tinned squid were 0.18 and 0.012 mg/kg, respectively. As a consequence of whole squid processing, highly elevated levels of cadmium, and also somewhat higher levels of some of the other trace metals, were found in the edible parts of the tinned squid. The content of cadmium in the edible parts of the squid in all instances exceed, and for edible parts of the tinned whole squid considerably exceed, the proposed tolerance limit for cadmium in fishery products (0.05 mg/kg).

Animals↗
PubMed1985

Tin protoporphyrin inhibits carbon monoxide production in adult mice.

We studied the effect of tin protoporphyrin, a potent inhibitor of heme oxygenase (EC 1.14.99.3), on carbon monoxide (CO) production in mature mice. Measurements of CO production provide a sensitive, noninvasive means of quantitating heme catabolism. CO accumulation in the gas space of closed chambers was decreased by about 25% for mice treated with two 50 nmol/g doses of tin protoporphyrin as compared to saline-treated controls. Calculated rates of CO production were 0.28 +/- 0.07 and 0.40 +/- 0.05 nmol X g-1 X h-1 for mice injected with tin protoporphyrin and saline, respectively (p less than 0.01). When hemin (125 nmol/g) was administered to simulate hemolysis, CO production increased markedly in both saline- and tin protoporphyrin-treated mice. However, the rate of CO production in tin protoporphyrin-treated mice was only 44% that of saline-treated animals (p less than 0.0001). These studies demonstrate that tin protoporphyrin inhibits heme catabolism in both the basal- and heme-loaded states and confirm that this inhibition is at the heme oxygenase step in the heme to bilirubin pathway.

Animals↗
PubMed2004

Vitamin status of high altitude (3660 m) acclimatized human subjects during consumption of tinned rations.

OBJECTIVE: To find out the nutritional status of sea-level residents acclimated to an altitude of 3660 m with respect to vitamin and nutrient requirements while consuming fresh and tinned rations. METHODS: Initially, high altitude acclimatized human subjects (n = 40) were evaluated for their general nutritional status along with energy intake and expenditure and physical fitness score while they were on fresh rations. Thereafter, subjects were fed tinned rations in two groups of 20 each. Of the two groups, one group had vitamin supplementation and the other was without any vitamin supplementation for 30 days. Thereafter, all the variables were studied once again. RESULTS: Daily total energy intake when subjects consumed fresh and tinned rations was 19.087 +/- 0.347 MJ and 19.417 +/- 0.342 MJ, respectively, whereas the total energy expenditure was 15.705 +/- 1.054 MJ per day for both the groups. After consuming tinned rations for 30 days, the placebo group showed a significant (P < .01) decrease in levels of plasma vitamin A and erythrocyte trans-ketolase activity (a marker of thiamin status) in comparison to the status when subjects were on fresh rations. However, levels of these variables were well within acceptable range. Subjects maintained their body weights and physical fitness scores. No clinical deficiency was seen after consuming tinned rations for 30 days. CONCLUSION: The study indicates that no additional vitamin supplementation is required at high altitude after acclimatization when consuming fresh rations and at least for 30 days when consuming tinned rations.

Acclimatization↗
PubMedDate not supplied

The neurotoxicity of environmental pollutants: the effects of tin (Sn2+) on acetylcholine-induced currents in greater pond snail neurons.

Inorganic and organic tin compounds present in aqueous ecosystems have diverse effects on the behavior of living organisms. With the aim of identifying possible correlates of these actions, we studied the effects of both types of Sn2+. The effects of SnCl2 and Sn(CH3)2 on acetylcholine-activate currents were studied on identified neurons of the mollusk Lymnaea stagnalis L. using a two-microelectrode membrane potential clamping technique and by intracellular dialysis with potential and ion concentration clamping. Experiments were performed on single neurons after isolation and on whole ganglion preparations. SnCl2 decreased acetylcholine-induced influx currents; the effect was dose-dependent. The effective threshold concentration, measured by the two-microelectrode membrane potential clamping method, was 0.1 microM, with saturation occurring at 5 microM SnCl2. After a 10-min preapplication of SnCl2, the effect was stronger (20%) than after treatment for 3 min (7%). Similar results were obtained after application of tin using the intracellular dialysis method with potential and ion concentration clamping. After preapplication of 10 microM SnCl2 for 1 min, acetylcholine-induced influx currents decreased by 41%, we compared differences in the effects induced by inorganic and organic tin compounds. Sn(CH3) induced a decrease in the amplitude of acetylcholine-induced currents in the same way as inorganic tin. The effect of Sn(CH3)2 was irreversible and stronger as the preapplication time increased. These results support the previous conclusion that agonist-activated channels are an important target for the actions of toxic metals. It is concluded that direct actions on neuron membranes represent an important component in the modulation of synaptic transmission and that this should be considered in studies of the mechanisms of toxicity of tin.

Acetylcholine↗
PubMed1989

Effects of tin and lead on organ levels of essential minerals in rabbits.

The effect of tin and lead on levels of essential metals (Zn, Cu, Ca, Fe) in rabbit tissues was compared in relation to the route of administration. Animals received intraperitoneally, or per os, SnCl2 (2 mg Sn/kg) or Pb(CH3COO)2 (3.5 mg Pb/kg) every day for 5 d or for 1 mo. Copper, zinc, iron, and calcium were determined by AAS in the liver, kidneys, spleen, brain, bone marrow, and blood; lead and tin concentration were measured in the blood of animals. Tin and lead administered per os caused either no changes or the decreased concentration of endogenous metals in several tissues. The other route of administration (ip) of both metals generally contributed to the increased storage of essential elements. Blood tin levels of tin treated animals were only about less than or equal to 1/10 of blood lead concentrations of rabbits exposed to lead.

Animals↗
PubMed1983

The effect of tin chloride on the structure and function of DNA in human white blood cells.

Tin compounds are being used increasingly in the home, in industry and in medicine. There have been relatively few studies on the long term biological effects of this metal, although acute effects have been documented. In this report we describe experiments which show that tin(II), as stannous chloride, is readily taken up by human white blood cells (WBC) and can cause damage to DNA. Damage was detected in WBC after exposure to 10-50 microM tin(II) for 30 min at either 0 degree or 37 degrees C. The amount of damage observed was more extensive than that produced by exposure of cells to equimolar amounts of chromium(VI), a known carcinogen and DNA damaging agent. Additional indication of cellular damage is that exposure of human lymphocytes or mouse splenocytes to tin(II) interfered with their ability to be stimulated by the polyvalent mitogen concanavalin A (Con A). By contrast, tin(IV) was not taken up by cells, did not cause DNA damage nor did it inhibit stimulation of DNA synthesis in cells that were exposed to Con A.

Biological Transport↗
PubMed2001

Stille couplings catalytic in tin: the "Sn-O" approach.

A one-pot tandem Pd-catalyzed hydrostannylation/Stille coupling protocol for the stereoselective generation of vinyltins and their subsequent union, employing only catalytic amounts of tin, is described. By recycling the organotin halide Stille byproduct back to organotin hydride, a hydrostannylation/cross-coupling sequence can be carried out with catalytic amounts of tin. Such a process is most effective with Me(3)SnCl serving as the tin source. This protocol allows a 94% reduction of the tin requirement, while maintaining good yields (up to 90%) for a variety of Stille products. Furthermore, since one cycle requires the tin to undergo at least four transformations, each moiety of trialkyltin is experiencing a minimum of 60 reactions over the course of the hydrostannylation/Stille sequence.

Organotin Compounds↗
PubMed2000

Effect of inorganic and organic tin compounds on ACh- and voltage-activated Na currents.

1. Inorganic tin and organotin compounds, occurring in aquatic ecosystems, are toxic and can cause behavioral abnormalities in living organisms. To determine the possible neuronal basis of these actions, the effects of both forms of Sn were studied on identified neurones of the mollusk, Lymnaea stagnalis L. 2. SnCl2 caused a dose-dependent decrease in the acetylcholine (Ach)-induced inward current. The effective threshold concentration, measured by a two microelectrode voltage clamp technique, was 0.1 microM, and the maximal effect occurred at 5 microM SnCl2. The depression of the inward current was greater after a 10 min preapplication (20%) than after 3 min treatment (7%). 3. The next series of experiments compared the actions of inorganic or organic tin compounds. In whole cell clamp experiments both (CH3)2SnCl2 and (CH3)3SnCl, like inorganic Sn, decreased the amplitude of Ach-induced current. Increasing the duration of the preapplication time resulted in an increase in the effect, but the action was not reversible. SnCl2 treatment caused a concentration-dependent alteration (initial potentiation followed by depression) of the amplitude of I(Na(V)) over the whole voltage range and slightly shifted the I-V curves to the left. In contrast, trimethyl tin decreased the amplitude of I(Na(V)) only at high concentration (100 microM). The activation time course of I(Na) was increased (tau = 0.43 ms in control and 0.55 ms in Sn), but Sn did not alter the inactivation parameters (tau = 3.43 and 3.41 ms). 4. These results support earlier findings that agonist- and voltage-activated channels are direct targets of toxic metals. We conclude that tin in both inorganic and organic forms acts at neuronal membranes to modulate synaptic transmission through direct actions on agonist-activated ion channels, and suggest that these actions may be the basis of the altered behavior of animals in tin-polluted environments.

Animals↗
PubMed1999

[Determination of inorganic and organic tin in water samples by graphite furnace atomic absorption spectrometry].

This paper proposed a method for the determination of inorganic tin and organotin species. Total tin contents can be directly detected by zirconium-coated graphite furnace atomic absorption spectrometry,while the organotin was detected by hydride generation combined with solvent extraction and the difference between the total tin and organotin was inorganic tin. The detection limits were 58 pg and 27 pg for organotin and inorganic tin,respectively. The relative standard deviations of this procedure, were 2.13% and 2.04%, respectively. Several water samples were analyzed by this method. The recoveries ranging from 90.5% and 98.5% were obtained.

Spectrophotometry, Atomic↗
PubMed1979

[Square-wave polarographic determination of tin in products of the food processing industry].

A square-wave polarographic method suitable for measuring tin in canned products and raw materials for food industry was examined. After wet digestion of the sample tin was directly determined from the acidic stock solution gained. If 10 ml of the stock solution was equivalent to 1 g sample,--varying sensitivity of the instrument--tin could be determined in the range of 5 micrograms/g--400 micrograms/g with +/- 5% relative error. By increasing sensitivity of the instrument this range could be extended to as little as 0,5 micrograms tin/g sample. The optimal quantity of hydrochloric acid to be added to the sulphuric acid solution of the digested sample before the instrumental measurement was determined by means of model solutions. Examinations concerning interference of lead were also performed. It is established, that if the ratio of Sn/Pb is at least 4/1, lead does not interfere with the polarographic tin determination. If the ratio of Sn/Pb is 2/1 or 1/1 tin content can be calculated after measuring the height of the peak of lead in sulphuric acid electrolyte. The method was applied for several canned products and comparative tests were performed with the spectrophotometric method given in the Hungarian standard MSZ 3612/7-77.

Animals↗
PubMed1980

Effect of tin on porphyrin biosynthesis.

Certain disturbances in porphyrin biosynthesis were examined in rabbits administered with either tin or lead. Stannous chloride treatment increased the concentrations of coproporphyrin in blood and urine, as did lead acetate treatment. No effect of tin on 5-aminolevulinic acid concentration was observed in blood and urine, whereas lead treatment increased it markedly in both. Tin profoundly inhibited the activity of 5-aminolevulinate dehydratase in blood, but did not alter it in liver although tin content in liver was considerably higher than that in blood. In contrast to a prolonged inhibition of erythrocyte 5-aminolevulinate dehydratase by lead, tin inhibition of erythrocyte 5-aminolevulinate dehydratase activity was rapidly reversed after the cessation of the metal treatment.

Aminolevulinic Acid↗
PubMed1999

Action of inorganic tin and organotins on a hydrocarbon-using yeast, Candida maltosa.

Two inorganic tin compounds, as well as mono- and tri-substituted methyl-, butyl-, and phenyltins were examined for their interactions with a hydrocarbon-using strain of Candida maltosa. Neither of the inorganic tins (SnII and SnIV) inhibited growth at concentrations up to 0.8 mM while binding to the yeast cells occurred to levels of 0.3 and 0.23 mM Sn/g cells, respectively. Neither inorganic tin caused leakage of potassium from the yeast cells. Among the organotins, tributyl- and triphenyltins caused total viability loss and near maximum potassium loss at initial concentrations of 0.08 mM. For these compounds binding to the cells increased with increasing initial concentrations to maximum values of 0.51 and 0.65 mM Sn/g cells respectively. The other organotin compounds were not inhibitory and did not cause potassium leakage from the cells. Tin from them became cell associated only in the cases of monobutyl- and monophenyl tin, which were bound at markedly lower levels (<0.1 mM Sn/g cells). These results are consistent with the conclusion that the inhibitory compounds can act on the yeast cell membrane but, although binding to the cells is a prerequisite for growth inhibition and cell leakage, no simple correlation was established between binding levels and toxicity effects.

Candida↗
PubMed2005

Cytocompatibility of novel tin oxide thin films.

The capacity of tin oxide films to support cell growth was investigated. Three substrates were used for the test: glass coverslips, glass coverslips spin coated with tin oxide and commercially available 316 stainless steel. The wettabilities and surface roughness of the three surfaces were measured before seeding 3T3 fibroblasts onto the samples. The behaviour of the cells grown on the tin oxide was compared to the uncoated glass and the steel and results showed that the cell growth on tin oxide compared favourably with the other substrates. The surface wettability appeared to have the strongest effect on cell adhesion to tin oxide.

3T3 Cells↗
PubMed1984

The effect of exposure conditions upon the release of soluble copper and tin from dental amalgams.

The concentrations of soluble copper and tin which were generated by the corrosion of a number of different amalgams in both an artificial saliva and Ringer's solution are reported. Besides variations in solution composition, the effects of solution agitation and abrasive particle wear upon the release of soluble species are studied. Immersion only, moderate solution agitation, vigorous solution agitation with abrasive particle wear, and accelerated corrosion by both constant currents and cyclic voltammetry are included. The results indicate that an artificial saliva but not Ringer's solution is capable of generating high levels of soluble tin. With artificial saliva, agitation increases the amalgam weight losses and increases soluble copper and tin concentrations, whereas agitation with Ringer's solution decreases sample weight losses and decreases levels of soluble copper and tin. This latter effect is believed to be due to the increased oxygen supply to the amalgam surfaces with agitation and the greater ability for producing protective passivating films of the basic hydroxide and copper chlorides in solutions of higher chloride ion concentrations e.g. Ringer's solution. Abrasive particle wear, including pumice, alumina, glass beads, and silica gel had varied effects upon the release of soluble species. Depending upon the amalgam, the solution, and the abrasive combination, either larger increases in copper or in tin occurred or reduced concentrations.

Copper↗
PubMed2004

Particle size of tin and phytate colloid in sentinel node identification.

BACKGROUND: Sentinel node navigation surgery (SNNS) has recently been introduced for various types of carcinoma. Numerous radioisotopes are used as tracers for SNNS. However, few reports have examined particle sizes of isotope colloids used in SNNS. MATERIALS AND METHODS: Tin and phytate colloids were used in the present study. Isotonic sodium chloride and tin solutions were mixed ratios of 1:4, 1:2, 1:1, 2:1, and 4:1. Calcium solution and Tc-phytate were mixed at ratios of 1:4, 1:2, 1:1, 2:1 and 4:1. Particle size was measured using a Coulter Model N4SD Sub-micron Particle Analyzer. RESULTS: When isotonic sodium chloride and tin solutions were mixed at ratios of 1:4, 1:2, 1:1, 2:1, and 4:1, particle size was 47 +/- 9, 96 +/- 10, 712 +/- 83, 925 +/- 66 and 1079 +/- 132 nm, respectively. As the ratio of tin solution decreased, colloid particle size increased. Particle size of phytate colloid varied from 174 +/- 39 nm to 1222 +/- 283 nm, according to calcium concentration. Phytate colloid particle size became larger as the ratio of phytate solution decreased. CONCLUSIONS: We ascertained that the particle size of tin and phytate colloids is controllable by manipulating the conditions under which the colloids form. These results will offer useful information when SNNS is performed.

Calcium↗