On the pharmacology of the iodides

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Pyrite oxidation inhibition by a cross-linked lipid coating

The effect of a diacetylene-containing phospholipid on the oxidation of pyrite, FeS(2), was investigated. Earlier work reported by our research group showed that the adsorption of l,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine on pyrite suppressed the extent of its oxidation by about 75% over a specific time period. Results presented here show that the pre-exposure to UV radiation of this lipid after sorption onto pyrite results in a 90% suppression. Attenuated total reflection (ATR) Fourier transform infra-red spectroscopy (FTIR) suggests that the UV irradiation of the lipid does not result in degradation of the adsorbed layer. It is believed that the UV exposure results in the cross-linking and polymerization of the adsorbed phospholipid into a relatively impermeable barrier that separates the pyrite from the aqueous phase. The results of this study might have implications for the protection of pyrite from oxidation in the environment

Effect of fluoride toothpastes on enamel demineralization

BACKGROUND: It was the aim of this study to investigate the effect of four different toothpastes with differing fluoride compounds on enamel remineralization. METHODS: A 3 × 3 mm window on the enamel surface of 90 human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 6 groups and the lower half of the window was covered with varnish serving as control. The teeth were immersed in a toothpaste slurry containing: placebo tooth paste (group 1); remineralization solution (group 2); Elmex Anticaries (group 3); Elmex Sensitive (group 4); Blend-a-med Complete (group 5) and Colgate GRF (group 6). Ten teeth of each group were used for the determination of the F(- )content in the superficial enamel layer and acid solubility of enamel expressed in soluble phosphorus. Of 6 teeth of each group serial sections were cut and investigated with polarization light microscopy (PLM) and quantitative energy dispersive X-ray analysis (EDX). RESULTS: The PLM results showed an increased remineralization of the lesion body in the Elmex Anticaries, Elmex Sensitive and Colgate GRF group but not in the Blend-a-med group. A statistically significant higher Ca content was found in the Elmex Anticaries group. The fluoride content in the superficial enamel layer was significantly increased in both Elmex groups and the Blend-a-med group. Phosphorus solubility was significantly decreased in both Elmex groups and the Blend-a-med group. CONCLUSION: It can be concluded that amine fluoride compounds in toothpastes result in a clearly marked remineralization of caries like enamel lesions followed by sodium fluoride and sodium monofluorophosphate formulations

Oral health promotion: the economic benefits to the NHS of increased use of sugarfree gum in the UK.

INTRODUCTION: The effect of sugarfree gum (SFG) on the prevention of dental caries has been established for some time. With increased constraints placed on healthcare budgets, the importance of economic considerations in decision-making about oral health interventions has increased. The aim of this study was to demonstrate the potential cost savings in dental care associated with increased levels of SFG usage. METHODS: The analysis examined the amount of money which would hypothetically be saved if the UK 12-year-old population chewed more SFG. The number of sticks chewed per year and the caries risk reduction were modelled to create a dose response curve. The costs of tooth restoration, tooth extraction in primary care settings and under general anaesthetic were considered, and the effects of caries reduction on these costs calculated. RESULTS: If all members of the UK 12-year-old population chewed SFG frequently (twice a day), the potential cost savings for the cohort over the course of one year were estimated to range from £1.2 to £3.3 million and if they chewed three times a day, £8.2 million could be saved each year. Sensitivity analyses of the key parameters demonstrated that cost savings would still be likely to be observed even in scenarios with less significant increases in SFG use. CONCLUSION: This study shows that if levels of SFG usage in the teenage population in the UK could be increased, substantial cost savings might be achieved

Microsurgical third ventriculocisternostomy as an alternative to ETV: report of two cases

OBJECTIVE: To describe a microsurgical alternative to endoscopic third ventriculocisternostomy. METHODS: Two children with shunt-dependent hydrocephalus and multiple shunt revisions were considered candidates for third ventriculocisternostomy (TVS). Because of slit ventricles, an endoscopic approach was not possible and, therefore, both patients received a microsurgical TVS by a supraorbital approach. RESULTS: In both cases, microsurgical TVS was successful and the patients became shunt free. CONCLUSION: Microsurgical TVS by a supraorbital craniotomy is a viable alternative to endoscopic TVS in selected cases

Changes in Dry State Hemoglobin over Time Do Not Increase the Potential for Oxidative DNA Damage in Dried Blood

BACKGROUND: Hemoglobin (Hb) is the iron-containing oxygen transport protein present in the red blood cells of vertebrates. Ancient DNA and forensic scientists are particularly interested in Hb reactions in the dry state because both regularly encounter aged, dried bloodstains. The DNA in such stains may be oxidatively damaged and, in theory, may be deteriorated by the presence of Hb. To understand the nature of the oxidative systems potentially available to degrade DNA in the presence of dried Hb, we need to determine what molecular species Hb forms over time. These species will determine what type of iron (i.e. Fe(2+)/Fe(3+)/Fe(4+)) is available to participate in further chemical reactions. The availability of "free" iron will affect the ability of the system to undergo Fenton-type reactions which generate the highly reactive hydroxyl radical (OH*). The OH* can directly damage DNA. METHODOLOGY/PRINCIPAL FINDINGS: Oxygenated Hb (oxyHb) converts over time to oxidized Hb (metHb), but this happens more quickly in the dry state than in the hydrated state, as shown by monitoring stabilized oxyHb. In addition, dry state oxyHb converts into at least one other unknown species other than metHb. Although "free" iron was detectable as both Fe(2+) and Fe(3+) in dry and hydrated oxyHb and metHb, the amount of ions detected did not increase over time. There was no evidence that Hb becomes more prone to generating OH* as it ages in either the hydrated or dry states. CONCLUSIONS: The Hb molecule in the dried state undergoes oxidative changes and releases reactive Fe(II) cations. These changes, however, do not appear to increase the ability of Hb to act as a more aggressive Fenton reagent over time. Nevertheless, the presence of Hb in the vicinity of DNA in dried bloodstains creates the opportunity for OH*-induced oxidative damage to the deoxyribose sugar and the DNA nucleobases

The Use of Flow-Injection Analysis with Chemiluminescence Detection of Aqueous Ferrous Iron in Waters Containing High Concentrations of Organic Compounds

An evaluation of flow-injection analysis with chemiluminescence detection (FIA-CL) to quantify Fe2+(aq) in freshwaters was performed. Iron-coordinating and/or iron-reducing compounds, dissolved organic matter (DOM), and samples from two natural water systems were used to amend standard solutions of Fe2+(aq). Slopes of the response curves from ferrous iron standards (1 – 100 nM) were compared to the response curves of iron standards containing the amendments. Results suggest that FIA-CL is not suitable for systems containing ascorbate, hydroxylamine, cysteine or DOM. Little or no change in sensitivity occurred in solutions of oxalate and glycine or in natural waters with little organic matter

The effect of tidal forcing on biogeochemical processes in intertidal salt marsh sediments

<p>Abstract</p> <p>Background</p> <p>Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over several centimeters. In coastal marine sediments, however, the concentration of NOM is so high that the spatial resolution needed to characterize these processes cannot be achieved with conventional sampling techniques. In addition, coastal sediments are influenced by tidal forcing that likely affects the processes involved in carbon oxidation.</p> <p>Results</p> <p>In this study, we used in situ voltammetry to determine the role of tidal forcing on early diagenetic processes in intertidal salt marsh sediments. We compare ex situ measurements collected seasonally, in situ profiling measurements, and in situ time series collected at several depths in the sediment during tidal cycles at two distinct stations, a small perennial creek and a mud flat. Our results indicate that the tides coupled to the salt marsh topography drastically influence the distribution of redox geochemical species and may be responsible for local differences noted year-round in the same sediments. Monitoring wells deployed to observe the effects of the tides on the vertical component of porewater transport reveal that creek sediments, because of their confinements, are exposed to much higher hydrostatic pressure gradients than mud flats.</p> <p>Conclusion</p> <p>Our study indicates that iron reduction can be sustained in intertidal creek sediments by a combination of physical forcing and chemical oxidation, while intertidal mud flat sediments are mainly subject to sulfate reduction. These processes likely allow microbial iron reduction to be an important terminal electron accepting process in intertidal coastal sediments.</p