Enrichment of Geogenic Organoiodine Compounds in Alluvial-Lacustrine Aquifers: Molecular Constraints by Organic Matter

Organoiodine compounds (OICs) are the dominant iodine species in groundwater systems. However, molecular mechanisms underlying the geochemical formation of geogenic OICs-contaminated groundwater remain unclear. Based upon multitarget field monitoring in combination with ultrahigh-resolution molecular characterization of organic components for alluvial-lacustrine aquifers, we identified a total of 939 OICs in groundwater under reducing and circumneutral pH conditions. In comparison to those in water-soluble organic matter (WSOM) in sediments, the OICs in dissolved organic matter (DOM) in groundwater typically contain fewer polycyclic aromatics and polyphenol compounds but more highly unsaturated compounds. Consequently, there were two major sources of geogenic OICs in groundwater: the migration of the OICs from aquifer sediments and abiotic reduction of iodate coupled with DOM iodination under reducing conditions. DOM iodination occurs primarily through the incorporation of reactive iodine that is generated by iodate reduction into highly unsaturated compounds, preferably containing hydrophilic functional groups as binding sites. It leads to elevation of the concentration of the OICs up to 183 μg/L in groundwater. This research provides new insights into the constraints of DOM molecular composition on the mobilization and enrichment of OICs in alluvial-lacustrine aquifers and thus improves our understanding of the genesis of geogenic iodine-contaminated groundwater systems.

Histologic and Immunohistochemical Characterization of GA-Like Pathology in the Rat Subretinal Sodium Iodate Model

Purpose

Geographic atrophy (GA) is an advanced form of dry age-related macular degeneration with multifactorial etiology and no well-established treatment. A model recapitulating the hallmarks would serve as a key to understanding the underlying pathologic mechanisms better. In this report, we further characterized our previously reported subretinal sodium iodate model of GA.

Methods

Retinal degeneration was induced in rats (6-8 weeks old) by subretinal injections of NaIO3 as described previously. Animals were sacrificed at 3, 8 and 12 weeks after injection and eyes were fixed or cryopreserved. Some choroids were processed as flatmounts while other eyes were cryopreserved, sectioned, and immunolabeled with a panel of antibodies. Finally, some eyes were prepared for transmission electron microscopic (TEM) analysis.

Results

NaIO3 subretinal injection resulted in a well-defined focal area of retinal pigment epithelium (RPE) degeneration surrounded by viable RPE. These atrophic lesions expanded over time. RPE morphologic changes at the border consisted of hypertrophy, multilayering, and the possible development of a migrating phenotype. Immunostaining of retinal sections demonstrated external limiting membrane descent, outer retinal tubulation (ORT), and extension of Müller cells toward RPE forming a glial membrane in the subretinal space of the atrophic area. TEM findings demonstrated RPE autophagy, cellular constituents of ORT, glial membranes, basal laminar deposits, and defects in Bruch's membrane.

Conclusions

In this study, we showed pathologic features of a rodent model resembling human GA in a temporal order through histology, immunofluorescence, and TEM analysis and gained insights into the cellular and subcellular levels of the GA-like phenotypes.

Translational Relevance

Despite its acute nature, the expansion of atrophy and the GA-like border in this rat model makes it ideal for studying disease progression and provides a treatment window to test potential therapeutics for GA.

Suppressor of cytokine signaling 3-derived peptide as a therapeutic for inflammatory and oxidative stress-induced damage to the retina

Purpose

Inflammation and oxidative stress contribute to age-related macular degeneration (AMD) and other retinal diseases. We tested a cell-penetrating peptide from the kinase inhibitory region of an intracellular checkpoint inhibitor suppressor of cytokine signaling 3 (R9-SOCS3-KIR) peptide for its ability to blunt the inflammatory or oxidative pathways leading to AMD.

Methods

We used anaphylatoxin C5a to mimic the effect of activated complement, lipopolysaccharide (LPS), and tumor necrosis factor alpha (TNFα) to stimulate inflammation and paraquat to induce mitochondrial oxidative stress. We used a human retinal pigment epithelium (RPE) cell line (ARPE-19) as proliferating cells and a mouse macrophage cell line (J774A.1) to follow cell propagation using microscopy or cell titer assays. We evaluated inflammatory pathways by monitoring the nuclear translocation of NF-κB p65 and mitogen-activated protein kinase p38. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot were used to evaluate the induction of inflammatory markers. In differentiated ARPE-19 monolayers, we evaluated the integrity of tight junction proteins through microscopy and the measurement of transepithelial electrical resistance (TEER). We used intraperitoneal injection of sodium iodate in mice to test the ability of R9-SOC3-KIR to prevent RPE and retinal injury, as assessed by fundoscopy, optical coherence tomography, and histology.

Results

R9-SOCS3-KIR treatment suppressed C5a-induced nuclear translocation of the NF-kB activation domain p65 in undifferentiated ARPE-19 cells. TNF-mediated damage to tight junction proteins in RPE, and the loss of TEER was prevented in the presence of R9-SOCS3-KIR. Treatment with the R9-SOCS3-KIR peptide blocked the C5a-induced expression of inflammatory genes. The R9-SOCS3-KIR treatment also blocked the LPS-induced expression of interleukin-6, MCP1, cyclooxygenase 2, and interleukin-1 beta. R9-SOCS3-KIR prevented paraquat-mediated cell death and enhanced the levels of antioxidant effectors. Daily eye drop treatment with R9-SOCS3-KIR protected against retinal injury caused by i.p. administration of sodium iodate.

Conclusions

R9-SOCS3-KIR blocks the induction of inflammatory signaling in cell culture and reduces retinal damage in a widely used RPE/retinal oxidative injury model. As this peptide can be administered through corneal instillation, this treatment may offer a convenient way to slow down the progression of ocular diseases arising from inflammation and chronic oxidative stress.

Abiotic and Biotic Reduction of Iodate Driven by Shewanella oneidensis MR-1

Iodate (IO3-) can be abiotically reduced by Fe(II) or biotically reduced by the dissimilatory Fe(III)-reducing bacterium Shewanella oneidensis (MR-1) via its DmsEFAB and MtrCAB. However, the intermediates and stoichiometry between the Fe(II) and IO3- reaction and the relative contribution of abiotic and biotic IO3- reduction by biogenic Fe(II) and MR-1 in the presence of Fe(III) remain unclear. In this study, we found that abiotic reduction of IO3- by Fe(II) produced intermediates HIO and I- at a ratio of 1:2, followed by HIO disproportionation to I- and IO3-. Comparative analyses of IO3- reduction by MR-1 wild type (WT), MR-1 mutants deficient in DmsEFAB or MtrCAB, and Shewanella sp. ANA-3 in the presence of Fe(III)-citrate, Fe(III) oxides, or clay minerals showed that abiotic IO3- reduction by biogenic Fe(II) predominated under iron-rich conditions, while biotic IO3- reduction by DmsEFAB played a more dominant role under iron-poor conditions. Compared to that in the presence of Fe(III)-citrate, MR-1 WT reduced more IO3- in the presence of Fe(III) oxides and clay minerals. The observed abiotic and biotic IO3- reduction by MR-1 under Fe-rich and Fe-limited conditions suggests that Fe(III)-reducing bacteria could contribute to the transformation of iodine species and I- enrichment in natural iodine-rich environments.

Dissolved iodine in the Changjiang River Estuary, China

The distribution and behavior of total dissolved iodine (TDI) and its species-iodate, iodide, and dissolved organic iodine (DOI) in the Changjiang River Estuary (CJE) surface and subsurface waters were studied along the salinity gradient. Results showed that TDI concentration in the freshwater endmember of CJE was 0.037 μM and existed as iodide. Although the transformation of dissolved iodine forms was active, TDI showed a conservative behavior, ranging from 0.037 μM to 0.42 μM in the estuary. Iodate showed removal behavior (ranging within 0-0.277 μM), iodide showed additive behavior (ranging within 0.037-0.131 μM), whereas DOI showed additive (0 < salinity < 20) (ranging within 0-0.099 μM) and removal (20 < salinity < 33.5) behavior (ranging within 0.099-0.022 μM). The iodine atoms in DOI were supplied primarily by iodide when salinity was <10 but by iodate when salinity was >10. The iodine-carbon ratios in DOI from different sources were more than 10 times different. The annual flux of iodine in the Changjiang River was 4.0 × 109g, accounting for about 4% of the global river iodine flux.

Improvement of the Stability of IO3--, SeO32--, and SeO42--Coprecipitated Barite after Treatment with Phosphate

Coprecipitation of radionuclides with barite has been studied to remove radionuclides from radioactive liquid waste because of its excellent removal efficiency; however, little information exists concerning the stability of the ions coprecipitated with barite. This study systematically investigated the stability of iodate, selenite, and selenate coprecipitated with barite via leaching tests. These oxyanions were gradually leached from the oxyanion-bearing barite into ultrapure water over time. Leaching of the oxyanions significantly increased in leaching solutions containing NaCl (pH 5.3), NaNO₃ (pH 5.9), and Na₂SO₄ (pH 5.7). Conversely, leaching of the oxyanions was suppressed in KH₂PO₄ solution (pH 8.5), indicating that phosphate stabilized the oxyanion-bearing barite. The effect of phosphate treatment on oxyanion-bearing barite was further investigated. The results showed that the barite surface was modified with phosphate, and a thin surface layer of a barium phosphate-like structure was formed. The amount of oxyanions leached from the phosphate-treated samples into leaching solutions containing NaCl or NaNO₃ was much lower than the amounts leached from the untreated barite samples into ultrapure water. The barite coprecipitation combined with subsequent phosphate treatment may be a promising method to efficiently remove iodate, selenite, and selenate from wastewater and stabilize them as barite coprecipitates.

Unexpectedly significant stabilizing mechanism of iodous acid on iodic acid nucleation under different atmospheric conditions

Iodous acid (HIO₂) has been shown to play a stabilizing role in the nucleation of iodic acid (HIO₃) (He et al., 2021). However, the stabilization effect and specific stabilizing mechanism of HIO₂ on HIO₃ nucleation under different atmospheric conditions remain unclear. Therefore, we studied these two issues under different temperatures and nucleation precursor concentrations using density functional theory combined with the Atmospheric Cluster Dynamics Code. We found that HIO₂ can form clusters with HIO₃ via strong hydrogen bonds, halogen bonds, and proton-transfer, substantially enhancing the stability of HIO₃ clusters and decreasing the energy barrier of HIO₃-based cluster formation at different temperatures and nucleation precursor concentrations. The particle formation rate and cluster concentrations of HIO₃-HIO₂ nucleation were negatively correlated with temperature and positively correlated with HIO₂ concentration. The enhancements by HIO₂ on the particle formation rate and cluster concentration of HIO₃ nucleation were positively correlated with temperature and HIO₂ concentration. Interestingly, even at a low HIO₂ concentration (1.0 × 10⁵ molecules cm^-3), the enhancement on the particle formation rate and cluster concentration of HIO₃ nucleation by HIO₂ were both unexpectedly up to 4.1 × 10⁴-fold at 283 K. Therefore, HIO₃-HIO₂ nucleation can be extremely rapid in cold regions, and the enhancement by HIO₂ can be significant, especially in warm regions even at relatively high HIO₂ concentrations.

The Lyotropic Nature of Halates: An Experimental Study

Unlike halides, where the kosmotropicity decreases from fluoride to iodide, the kosmotropic nature of halates apparently increases from chlorate to iodate, in spite of the lowering in the static ionic polarizability. In this paper, we present an experimental study that confirms the results of previous simulations. The lyotropic nature of aqueous solutions of sodium halates, i.e., NaClO₃, NaBrO₃, and NaIO₃, is investigated through density, conductivity, viscosity, and refractive index measurements as a function of temperature and salt concentration. From the experimental data, we evaluate the activity coefficients and the salt polarizability and assess the anions' nature in terms of kosmotropicity/chaotropicity. The results clearly indicate that iodate behaves as a kosmotrope, while chlorate is a chaotrope, and bromate shows an intermediate nature. This experimental study confirms that, in the case of halates XO₃^-, the kosmotropic-chaotropic ranking reverses with respect to halides. We also discuss and revisit the role of the anion's polarizability in the interpretation of Hofmeister phenomena.

Emerging periodate-based oxidation technologies for water decontamination: A state-of-the-art mechanistic review and future perspectives

With the ever-increasing severity of the ongoing water crisis, it is of great significance to develop efficient, eco-friendly water treatment technologies. As an emerging oxidant in the advanced oxidation processes (AOPs), periodate (PI) has received worldwide attention owing to the advantages of superior stability, susceptible activation capability, and high efficiency for decontamination. This is the first review that conducts a comprehensive analysis of the mechanism, pollutant transformation pathway, toxicity evolution, barriers, and future directions of PI-based AOPs based on the scientific information and experimental data reported in recent years. The pollutant elimination in PI-based AOPs was mainly attributed to the in situ generate reactive oxygen species (e.g., ^•OH, O(³P), ¹O₂, and O₂^•-), reactive iodine species (e.g., IO₃^• and IO₄^•), and high-valent metal-oxo species with exceptionally high reactivity. These reactive species were derived from the PI activated by the external energy, metal activators, alkaline, freezing, hydroxylamine, H₂O_2, etc. It is noteworthy that direct electron transport could also dominate the decontamination in carbon-based catalyst/PI systems. Furthermore, PI was transformed to iodate (IO₃^-) stoichiometrically via an oxygen-atom transfer process in most PI-based AOPs systems. However, the production of I₂, I^-, and HOI was sometimes inevitable. Furthermore, the transformation pathway of typical micropollutants was clarified, and the in silico QSAR-based prediction results indicated that most transformation products retained biodegradation recalcitrance and multi-endpoint toxicity. The barriers faced by the PI-based AOPs were also clarified with potential solutions. Finally, future perspectives and research directions are highlighted based on the current state of PI-based AOPs. This review enhances our in-depth understanding of PI-based AOPs for pollutant elimination and identifies future research needs to focus on the reduction of toxic byproducts.

Optimization and assessment of an electrochemical advanced oxidation system for synthetic stormwater treatment

Electrochemical advanced oxidation processes (eAOPs) such as the current advanced oxidation system (AOS) are a type of electrochemical wastewater treatment that creates oxidative species, such as iodide species, chloride species, and hydroxyl radicals, that can treat even the most recalcitrant contaminants. It is important to determine the concentrations and locations of oxidative species in eAOPs for optimization of the wastewater treatment process. In this study, a spectrophotometric methodology was used to determine concentrations of iodide and chloride oxidative species (starting at 10, 25, and 50 ppm) within an AOS under various input voltages (6, 12, and 24 V). Overall, it was found that iodate and chlorite were the dominant species created in their respective treatments. Additionally, the concentration of iodide oxidative species increased with increasing voltage, whereas the chloride species decreased with increasing voltage. The optimal conditions for the efficient creation of AOS oxidative species were 12 V and 10 ppm potassium iodide and 6 V and 10 ppm sodium chloride, respectively. In addition, the use of iodide is recommended for wastewater treatment using the AOS to effectively create oxidative species. Following optimization, the AOS performance was tested for synthetic stormwater. Results indicated that the AOS performed well for reduction of Escherichia coli; however, reduction of other contaminants was inconsistent as would be expected given the AOS was optimized for disinfection, not decontamination. Further AOS optimization for decontamination would be expected to result in improved decontamination performance.

127I and 129I species in the English Channel and its adjacent areas: Uncovering impact on the isotopes marine pathways

Radioactive iodine-129 has been released from the La Hague nuclear fuel reprocessing facility (NRF) into the English Channel, but the distribution and transformation of the isotope species, and environmental consequences have not been fully characterized in the Channel. Here we present data on iodine isotopes (¹²⁹I and ¹²⁷I) species in surface water of the English Channel and the southern Celtic Sea. Compared to ¹²⁷I species, the concentrations of ¹²⁹I^- and ¹²⁹IO₃^- show more variations, but iodate is the major species for both ¹²⁹I and ¹²⁷I. Our data provide new information regarding iodide-iodate inter-conversion showing that water dilution and mixing are the main factors affecting the ¹²⁷I and ¹²⁹I species distribution in the Channel. Some reduction of iodate occurs within the English Channel and mainly in the west part because of biotic processes. The ¹²⁹I species transformation is overall insignificant, especially in the eastern Channel, where a constant value of ¹²⁹IO₃^-/¹²⁹I is observed, which might characterize the La Hague wastewater signal. In the Celtic Sea, oxidation of iodide can be traced by ¹²⁷I and ¹²⁹I species. On a larger scale, ¹²⁹I generally experienced an oxidation process in the Atlantic Ocean, while in the coast of shallow shelf seas, new produced ¹²⁹I^- can be identified, especially in the German Bight and the Baltic Sea. The data of ¹²⁹I species in the English Channel can provide estimate of redox rates in a much broader marine areas if the transit time of ¹²⁹I from La Hague is well-defined. Furthermore, estimate of inventories for ¹²⁹I and its species in the Channel, and fluxes of ¹²⁹I species from the English Channel to the North Sea add important information to the geochemical cycle of ¹²⁹I.

Transport of tetracycline in saturated porous media: combined functions of inorganic ligands and solution pH

To date, there is still very little knowledge about the combined effects of typical inorganic ligands and solution pH values on mobility characteristics of tetracycline (TC) through saturated aquifer media. In this work, three typical inorganic ligands (i.e., phosphate, silicate, and iodate) were employed in the transport experiments. Generally, all the ligands promoted TC mobility over the pH range of 5.0-9.0 owing to the enhanced electrostatic repulsion between sand grains and TC anionic forms (i.e., TC^- and TC^2-) as well as the competitive deposition between ligands and antibiotic molecules for attachment sites. Furthermore, the transport-enhancement effects of ligands on TC intensively depended on ligand type and followed the sequence of phosphate > silicate > iodate. This phenomenon was ascribed to their different molecular sizes and binding abilities to sand grains. Interestingly, the differences in extents of enhanced effects of various inorganic ligands on TC transport varied with background solution pH due to pH-induced different extents of deposition site competition effects. Moreover, the two-site nonequilibrium model (which accounts for an equilibrium site and a kinetic site) as well as adsorption and kinetic studies were performed to help interpret the controlling mechanisms for the synergistic effects of inorganic ligands and solution pH on TC transport in saturated quartz sand. The findings of our study clearly demonstrate that inorganic ligands may be critical factors in assessing the fate and transport of antibiotics in groundwater systems.

Kinetics and mechanisms of the carbamazepine degradation in aqueous media using novel iodate-assisted photochemical and photocatalytic systems

The present study investigates the kinetics and mechanisms of carbamazepine (CBZ) degradation using a novel UV/iodate (IO₃^-) system for the first time and explores the influence of process conditions on its degradation. UV/IO₃^- showed high degradation efficiencies in a wide range of pHs, especially under neutral and acidic conditions, indicating that the system can be considered as a promising method to deal with effluents under various pH conditions. Radical scavenging experiments show that both iodine radicals (IO, IO₂ and IO₃) and hydroxyl radicals play an important role in CBZ degradation. Furthermore, the combination of UV/IO₃^- with TiO₂ was studied to explore the potential of the addition of IO₃^- to improve the efficiency of the conventional TiO₂ photocatalytic system. Scavenging experiments indicated that iodine radicals (IO, IO₂ and IO₃) were mainly involved in the degradation of CBZ in the UV/IO₃^-/TiO₂ system, and the reaction mechanism equations were proposed for the first time for the studied UV/IO₃^-/TiO₂ system. Several degradation products and four possible pathways of CBZ degradation were also elucidated using ultra-high-performance liquid chromatography in combination with a quadrupole time-of-flight mass spectrometer (Q-TOF MS). Respirometric tests indicated that the treatment has a positive impact on biomass behavior during subsequent biological purification, highlighting that the developed IO₃^--assisted AOPs are eco-friendly.

Sodium-Iodate Injection Can Replicate Retinal Degenerative Disease Stages in Pigmented Mice and Rats: Non-Invasive Follow-Up Using OCT and ERG

Purpose: The lack of suitable animal models for (dry) age-related macular degeneration (AMD) has hampered therapeutic research into the disease, so far. In this study, pigmented rats and mice were systematically injected with various doses of sodium iodate (SI). After injection, the retinal structure and visual function were non-invasively characterized over time to obtain in-depth data on the suitability of these models for studying experimental therapies for retinal degenerative diseases, such as dry AMD. Methods: SI was injected into the tail vein (i.v.) using a series of doses (0–70 mg/kg) in adolescent C57BL/6J mice and Brown Norway rats. The retinal structure and function were assessed non-invasively at baseline (day 1) and at several time points (1–3, 5, and 10-weeks) post-injection by scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), and electroretinography (ERG). Results: After the SI injection, retinal degeneration in mice and rats yielded similar results. The lowest dose (10 mg/kg) resulted in non-detectable structural or functional effects. An injection with 20 mg/kg SI did not result in an evident retinal degeneration as judged from the OCT data. In contrast, the ERG responses were temporarily decreased but returned to baseline within two-weeks. Higher doses (30, 40, 50, and 70 mg/kg) resulted in moderate to severe structural RPE and retinal injury and decreased the ERG amplitudes, indicating visual impairment in both mice and rat strains. Conclusions: After the SI injections, we observed dose-dependent structural and functional pathological effects on the retinal pigment epithelium (RPE) and retina in the pigmented mouse and rat strains that were used in this study. Similar effects were observed in both species. In particular, a dose of 30 mg/kg seems to be suitable for future studies on developing experimental therapies. These relatively easily induced non-inherited models may serve as useful tools for evaluating novel therapies for RPE-related retinal degenerations, such as AMD.

A ninety-six well plate as headspaces with moist starch indicator paper as a cover for the determination of ascorbic acid by iodate oxidation and formation of volatile iodine

This work presents the use of a 96-well plate as headspaces for the determination of ascorbic acid in samples loaded in the 96-well plate. Ascorbic acid in the sample is oxidized to iodide by the addition of excess acidic iodate solution into the well. The iodide is further oxidized by the remaining iodate to molecular iodine. A single sheet of moist starch indicator paper is immediately placed over the 96-well plate after the addition of the iodate with the moisture forming a gas seal. The iodine gas in each well diffuses through the headspace to react with the starch paper producing circular areas of a colored starch-iodine complex. After 15 min the indicator paper is scanned, and the digital images of the complex are analyzed by using ImageJ software to obtain blue intensity values. The precision of the intensity values from 12 wells containing 20 μL of 2.84 mM standard ascorbic acid is <2% relative standard deviation. Optimal conditions for detection were investigated, including the starch concentration, the acidic iodate reagent, and the measurement time. The linear calibration range of ascorbic acid is 0.284-2.84 mM, based on the plot of concentration vs. -log(reflectance). The coefficient of determination (r²) is >0.998. Samples of fruit juice and dietary supplements were analyzed for their ascorbic acid contents. The results obtained from the headspace reflectance method are not statistically different from values obtained from the titration method using paired t-tests (α = 0.05).

Fate and transformation of iodine species during Mn(VII)/sulfite treatment in iodide-containing water

During oxidative treatment of iodide (I^- )-containing waters, I^- is easy to be oxidized into hypoiodous acid (HOI) by various oxidants and the further reaction of HOI with organic compounds can lead to the formation of iodinated disinfection by-products (I-DBPs). Oxidation of HOI to iodate (IO₃ ^- ) or reduction of HOI to I^- has been proposed to reduce the formation of I-DBPs. Because the reaction of HOI with sulfite proceeds rapidly, this study examined the fate of iodine and the formation of I-DBPs in Mn(VII)/sulfite process. Results showed that I^- was oxidized to HOI but the further formation of IO₃ ^- was suppressed due to the fast reduction of HOI to I^- by sulfite. The reactions of HOI with SO₃ ^2- and IO^- with SO₃ ^2- are the major pathways with species-specific second-order rate constants determined to be 1.12 × 10⁵  M^-1  s^-1 and 9.43 × 10⁷  M^-1  s^-1 , respectively. The rapid reaction of HOI with sulfite plays an essential role in minimizing the formation of iodinated products in HOI- and phenol-containing solutions. The toxic risk analysis showed that the toxicity of the generated DBPs from Mn(VII)/sulfite pre-oxidation followed by chlorination only changed slightly. PRACTITIONER POINTS: The decay of I^- was negligible in Mn(VII)/sulfite process. The rapid reaction of HOI with SO₃ ^2- resulted in the negligible generation of IO₃ ^- . Mn(VII)/sulfite process exerted slight influence on the formation of I-DBPs. Mn(VII)/sulfite process is promising for the pretreatment of I^- -containing water.

Chlorination decreases acute toxicity of iodophenols through the formation of iodate and chlorinated aliphatic disinfection byproducts

Highly toxic iodinated phenolic by-products were frequently detected in the oxidative treatment and disinfection of iodine-containing water. Herein, it was found that three model iodinated phenolic disinfection byproducts (DBPs), 2-iodophenol, 4-iodophenol and 2,4,6-triiodophenol, were reactive with HOCl, and the reaction rate constants (at pH 7.0 and 25℃) were 1.86 ×10², 1.62 ×10² and 7.5 ×10¹ M^-1s^-1, respectively. When HOCl was in excess (HOCl/iodophenol = 40/1, [iodophenol]₀ = 20 μM), acute toxicity of water sample containing iodophenols could be largely eliminated (> 85%), with the conversion of iodophenols into stable and non-toxic iodate (IO₃^-) and iodinated and chlorinated aliphatic DBPs. Besides IO₃^-, seven kinds of aromatic intermediate products including iodophenols, chloroiodophenols, iodoquinones, chloroiodoquinones, chloroquinones, chlorophenols, and coupling products were detected. C-I bond of iodophenols was cleaved in the reaction and the resulted aromatic products were further transformed into chlorinated aliphatic DBPs [trichloromethane (TCM), trichloroacetic acid (TCAA), dichloroacetic acid (DCAA), and chloral hydrate (CH)] (mg/L level) and iodinated trihalomethanes (μg/L level). HOCl was effective for converting iodophenols into IO₃^- and less toxic chlorinated aliphatic DBPs. Considering that chlorine was widely used as disinfectant, transformation and toxicity alteration of emerging DBPs during chlorination/booster chlorination warrant further investigations.

Photodegradation pathway of iodate and formation of I-THMs during subsequent chloramination in iodate-iodide-containing water

This study investigated the mechanisms of mixed IO₃^-/I^- system under UV irradiation in drinking water and compared the iodinated trihalomethanes (I-THMs) formation of a mixed IO₃^-/I^- system to that of single I^- and IO₃^- systems during subsequent chloramination. The effects of initial I^-/IO₃^- molar ratio, pH, and UV intensity on a mixed IO₃^-/I^- system were studied. The introduction of I^- enhanced the conversion rate of IO₃^- to reactive iodine species (RIS). Besides, IO₃^- degradation rate increased with the increase of initial I^- concentration and UV intensity and the decrease of pH value. In a mixed IO₃^-/I^- system, IO₃^- could undergo direct photolysis and photoreduction by hydrated electron (e_aq^-). Moreover, the enhancement of I-THM formation in a mixed IO₃^-/I^- system during subsequent chloramination was observed. The I-THM yields in a mixed IO₃^-/I^- system were higher than the sum of I-THMs produced in a single IO₃^- and I^- systems at all the evaluated initial I^- concentrations and pH values. The difference between I-THM formation in a mixed IO₃^-/I^- system and the sum of I-THMs in a single IO₃^- and I^- systems increased with the increase of initial I^- concentration. As the initial pH decreased from 9 to 5, the difference of I-THM yields enhanced, while the total I-THM yield of a mixed IO₃^-/I^- system and single I^- and IO₃^- systems decreased slightly. Besides, IO₃^--I^--containing water with DOC concentration of 2.5-4.5 mg-C/L, which mainly contained humic-acid substances, had a higher risk in I-THMs formation than individual I^--containing and IO₃^--containing water.

Effective removal of iodate by coprecipitation with barite: Behavior and mechanism

Radioactive iodine (¹²⁹I) is of great concern owing to its high mobility in the environment and long-term radiotoxicity. However, there is a lack of effective techniques for removing iodate (IO₃^-) from aqueous solution. This study aims to develop a new technique for removing radioactive iodate from contaminated solution by using barite (BaSO₄). We examined the coprecipitation mechanism of iodate by barite at the molecular level to determine the optimum conditions for iodate removal. Results showed that iodate was effectively removed from the aqueous solution by coprecipitation even in the presence of competitive anions. Based on comparison of our method with previous techniques, the iodate removal efficiency by barite was determined to be about two orders of magnitude greater than that by hydrotalcite-like layered double hydroxide at 10 mmol L^-1 Cl^-. Extended X-ray absorption fine structure analysis indicated that the incorporated iodate was strongly bound to the crystal lattice of barite by substituting the sulfate site in the structure when the iodine concentration was low. The charge compensation problem from the IO₃^- substitution in the SO₄^2- site was achieved by the substitution of Na⁺-IO₃^- pairs at the nearest Ba²⁺ site. Given the high removal efficiency and strong binding of iodate to barite, coprecipitation with barite is a promising tool for removing radioactive iodate from various aqueous solutions contaminated with iodate.

Protective effects of PARP1-inhibitory compound in dry age-related macular degeneration

Poly (ADP-ribose) polymerase 1 (PARP1)-dependent cell death in the retinal pigment epithelium (RPE) is implicated in dry age-related macular degeneration (AMD). Although PARP1 inhibitors are available for treating dry AMD, their delivery route is not ideal for patients. The aim of this study was to test the efficacy of a novel PARP1-inhibitory compound (PIC) in vitro and in vivo. This study presents PIC, a novel small molecule, with superior efficacy to PARP1 inhibitors in the market. PIC demonstrated a distinctive inhibitory profile against PARP isotypes than the FDA-approved PARP1 inhibitors. PIC inhibited PARP1 activation at an IC50 of 0.41 ± 0.15 nM in an enzyme-based assay in vitro and at IC50 and EC50 in ARPE-19 cells of 0.11 ± 0.02 nM and 0.22 ± 0.02 nM, respectively, upon H2O2 insult. PIC also moderated mitochondrial fission and depolarization and maintained cellular energy levels under oxidative stress in ARPE-19 cells. Furthermore, PIC demonstrated good corneal penetration in a rat model, presenting PIC as a promising candidate for eye drop therapeutics for dry AMD. When PIC was administered as an eye drop formulation, RPE morphology was preserved, maintaining the thickness of the outer nuclear layers under sodium iodate (SI) treatment in rats. In SI-treated rabbits, eye drop administration of PIC also retained the structural and functional integrity when analyzed using funduscopy and electroretinogram. Collectively, our data portray PIC as an attractive treatment measure for dry AMD.

A Novel HDL-Mimetic Peptide HM-10/10 Protects RPE and Photoreceptors in Murine Models of Retinal Degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness in the developed world. The retinal pigment epithelium (RPE) is a critical site of pathology in AMD. Oxidative stress plays a key role in the development of AMD. We generated a chimeric high-density lipoprotein (HDL), mimetic peptide named HM-10/10, with anti-oxidant properties and investigated its potential for the treatment of retinal disease using cell culture and animal models of RPE and photoreceptor (PR) degeneration. Treatment with HM-10/10 peptide prevented human fetal RPE cell death caused by tert-Butyl hydroperoxide (tBH)-induced oxidative stress and sodium iodate (NaIO₃), which causes RPE atrophy and is a model of geographic atrophy in mice. We also show that HM-10/10 peptide ameliorated photoreceptor cell death and significantly improved retinal function in a mouse model of N-methyl-N-nitrosourea (MNU)-induced PR degeneration. Our results demonstrate that HM-10/10 protects RPE and retina from oxidant injury and can serve as a potential therapeutic agent for the treatment of retinal degeneration.

Nitrite-Induced Activation of Iodate into Molecular Iodine in Frozen Solution

A new mechanism for the abiotic production of molecular iodine (I₂) from iodate (IO₃^-), which is the most abundant iodine species, in dark conditions was identified and investigated. The production of I₂ in aqueous solution containing IO₃^- and nitrite (NO₂^-) at 25 °C was negligible. However, the redox chemical reaction between IO₃^- and NO₂^- rapidly proceeded in frozen solution at -20 °C, which resulted in the production of I₂, I^-, and NO₃^-. The rapid redox chemical reaction between IO₃^- and NO₂^- in frozen solution is ascribed to the accumulation of IO₃^-, NO₂^-, and protons in the liquid regions between ice crystals during freezing (freeze concentration effect). This freeze concentration effect was verified by confocal Raman microscopy for the solute concentration and UV-visible absorption spectroscopy with cresol red (acid-base indicator) for the proton concentration. The freezing-induced production of I₂ in the presence of IO₃^- and NO₂^- was observed under various conditions, which suggests this abiotic process for I₂ production is not restricted to a specific region and occurs in many cold regions. NO₂^--induced activation of IO₃^- to I₂ in frozen solution may help explain why the measured values of iodine are larger than the modeled values in some polar areas.

Incorporation Modes of Iodate in Calcite

Iodate (IO₃^-) incorporation in calcite (CaCO₃) is a potential sequestration pathway for environmental remediation of radioiodine-contaminated sites (e.g., Hanford Site, WA), but the incorporation mechanisms have not been fully elucidated. Ab initio molecular dynamics (AIMD) simulations and extended X-ray absorption fine structure spectroscopy (EXAFS) were combined to determine the local coordination environment of iodate in calcite, the associated charge compensation schemes (CCS), and any tendency for surface segregation. IO₃^- substituted for CO₃^2- and charge compensation was achieved by substitution of Ca²⁺ by Na⁺ or H⁺. CCS that minimized the I-Na/H distance or placed IO₃^- at the surface were predicted by density functional theory to be energetically favored, with the exception of HIO₃, which was found to be metastable relative to the formation of HCO₃^-. Iodine K-edge EXAFS spectra were calculated from AIMD trajectories and used to fit the experimental spectrum. The best-fit combination consisted of a significant proportion of surface-segregated IO₃^- and charge compensation was predominantly by H⁺. Important implications are therefore that pH should strongly affect the extent of IO₃^- incorporation and that IO₃^- accumulated at the surface of CaCO₃ particles may undergo mobilization under conditions that promote calcite dissolution. These impacts need to be considered in calcite-based iodate remediation strategies.

Iodinated trihalomethane formation during chloramination of iodate-containing waters in the presence of zero valent iron

Iodide (I^-) and iodinated X-ray contrast media (ICM) are the primary iodine sources for the formation of iodinated disinfection byproducts (I-DBPs), and iodate (IO₃^-) is believed to be a desired sink of iodine in water. This study found that highly cytotoxic iodinated trihalomethanes (I-THMs) also can be generated from iodate-containing waters (without any other iodine sources) in the presence of zero valent iron (ZVI) during chloramination, which could be a big issue in the wide usage of iron pipes. The effect of major factors including ZVI dosage, NH₂Cl and IO₃^- concentrations, initial pH, Br^-/IO₃^- molar ratio, phosphate concentration, iron corrosion scales (goethite and hematite) on the formation of I-THMs were investigated. Formation of I-THMs from IO₃^- increased with the increase of ZVI dosage, IO₃^- and NH₂Cl concentrations. Chloramines can also remarkably accelerate the reduction of IO₃^- by ZVI. Peak I-THM formation was found at pH 8. As the Br^-/IO₃^- molar ratio increased from 0 to 20, I-THM formation considerably enhanced, especially for the bromine-incorporated species. Goethite and hematite enhanced the formation of I-THMs in the presence of ZVI. Additionally, a significant suppression on I-THM formation was observed with the addition of phosphate. Considering that a large number of water distribution networks contain unlined cast iron pipes, transformation of IO₃^- in the presence of ZVI during chloramination may contribute to the formation of I-THMs in such systems.

Transformation of iodide and formation of iodinated by-products in heat activated persulfate oxidation process

Formation of halogenated disinfection by-products (DBPs) in sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted considerable concerns recently. Previous studies have focused on the formation of chlorinated and brominated DBPs. This research examined the transformation of I^- in heat activated PS oxidation process. Phenol was employed as a model compound to mimic the reactivity of dissolved natural organic matter (NOM) toward halogenation. It was found that I^- was transformed to free iodine which attacked phenol subsequently leading to iodinated DBPs such as iodoform and iodoacetic acids. Iodophenols were detected as the intermediates during the formation of the iodoform and triiodoacetic acid (TIAA). However, diiodoacetic acid (DIAA) was formed almost concomitantly with iodophenols. In addition, the yield of DIAA was significantly higher than that of TIAA, which is distinct from conventional halogenation process. Both the facts suggest that different pathway might be involved during DIAA formation in SR-AOPs. Temperature and persulfate dose were the key factors governing the transformation process. The iodinated by-products can be further degraded by excessive SO₄^- and transformed to iodate. This study elucidated the transformation pathway of I^- in SR-AOPs, which should be taken into consideration when persulfate was applied in environmental matrices containing iodine.

Formation of iodinated trihalomethanes during UV/chloramination with iodate as the iodine source

Iodinated trihalomethanes (I-THMs) are a group of emerging disinfection by-products with high toxicity, and iodide (I(-)) as well as iodinated organic compounds are expected to be their iodine sources. Nevertheless, in this study, iodate (IO3(-)) was proven to be a new iodine source of I-THM formation during UV/chloramination. In the iodate-containing waters (without any other iodine sources), I-THM formation increased with the increase of UV dose, IO3(-) and NH2Cl concentrations. With the increase of Br(-)/IO3(-) molar ratio, I-THM formation (especially for the brominated species) increased. Besides, NOM species could affect I-THM formation from IO3(-) during UV/chloramination. Fulvic acid could promote IO3(-) phototransformation to I(-) but humic acid impeded the production of I(-) during UV irradiation. Under realistic drinking water treatment conditions (DOC = 5.0 mg-C/L, IO3(-) = 12.7 μg-I/L, UV dose = 50 mJ/cm(2), NH2Cl = 5 mg-Cl2/L), CHCl2I was detected as 0.17 μg/L using solid-phase microextraction method, and the production rate of I-THMs from IO3(-) was about 7% of that from I(-).

Enhanced retinal pigment epithelium regeneration after injury in MRL/MpJ mice

Regenerative medicine holds the promise of restoring cells and tissues that are destroyed in human disease, including degenerative eye disorders. However, development of this approach in the eye has been limited by a lack of animal models that show robust regeneration of ocular tissue. Here, we test whether MRL/MpJ mice, which exhibit enhanced wound healing, can efficiently regenerate the retinal pigment epithelium (RPE) after an injury that mimics the loss of this tissue in age-related macular degeneration. The RPE of MRL/MpJ and control AKR/J mice was injured by retro-orbital injection of sodium iodate at 20 mg/kg body weight, which titration studies indicated was optimal for highlighting strain differences in the response to injury. Five days after sodium iodate injection at this dose, electroretinography of both strains revealed equivalent retinal responses that were significantly reduced compared to untreated mice. At one and two months post-injection, retinal responses were restored in MRL/MpJ but not AKR/J mice. Bright field and fluorescence microscopy of eyecup cryosections indicated an initial central loss of RPE cells and RPE65 immunostaining in MRL/MpJ and AKR/J mice, with preservation of peripheral RPE. Phalloidin staining of posterior eye whole mounts confirmed this pattern of RPE loss, and revealed a transition region characterized by RPE cell shedding and restructuring in both strains, suggesting a similar initial response to injury. At one month post-injection, central RPE cells, RPE65 immunostaining and phalloidin staining were restored in MRL/MpJ but not AKR/J mice. BrdU incorporation was observed throughout the RPE of MRL/MpJ but not AKR/J mice after one month of administration following sodium iodate treatment, consistent with RPE proliferation. These findings provide evidence for a dramatic regeneration of the RPE after injury in MRL/MpJ mice that supports full recovery of retinal function, which has not been observed previously in mammalian eyes. This model should prove useful for understanding molecular mechanisms that underlie regeneration, and for identifying factors that promote RPE regeneration in age-related macular degeneration and related diseases.

Effect of quercetin on formation of choroidal neovascularization (CNV) in age-related macular degeneration(AMD)

PURPOSE

Age-related macular degeneration (AMD) as a disease entity is "dry" at early stage and made up of two main components at late stage: atrophic AMD and exudative AMD. Quercetin acts as an anti-oxidant to protect retinal pigment epithelial cells (RPE) from damaged by oxidative stress, but its effect on formation of choroidal neovascularization (CNV) in AMD is unclear. The aim of this study is to investigate the effect of quercetin on the formation of CNV in AMD.

METHODS

The development of CNV induced by laser was detected by fluorescein angiography (FA). Colored microsphere technique was used to determine the choroidal blood flow in ocular hypertensive rabbit eyes. In in vitro studies, HUVECs were treated with NaIO3, H2O2 and NaN3 to induce oxidative cell damages. The effect of quercetin on various oxidations-induced injuries in HUVECs was measured by MTT assay. HUVECs migration was assessed using a wound healing assay.

RESULTS

Quercetin significantly inhibited the formation of laser-induced CNV. The choroidal blood flow in rabbit eyes was significantly increased after quercetin instillation. In vitro results showed quercetin enhanced various oxidations-induced injuries in HUVECs and inhibited migration of HUVECs during wound healing.

CONCLUSION

Quercetin inhibited the formation of CNV both in vivo and in vitro and increased choroidal blood flow. It could become a promising candidate for the treatment of AMD.

[Functional improvement of injured retina following the adjuvant stem cell-based therapy. Preliminary report]

PURPOSE

The purpose of this study was to appraise the functional response of damaged retina to the stem cell-based therapy in mice. The majority of disorders leading to the irreversible vision loss in the developed world is caused by retinal degeneration. Since, recent reports emphasized regenerative potential of bone marrow stem marrow stem/progenitor cells (SPCs), we investigated here the beneficial effect of intravenously administrated SPCs on regeneration of acutely injured retina.

MATERIAL AND METHODS

Selective chemical injury of murine retinas was induced by intravenous administration of sodium iodate (NalO3) in its toxic dose. Flash electroretinogram (ERG), was performed in different time points after infusion of bone marrow-derived and negative for linage antigens population of SPCs.

RESULTS

Stem cell-based therapy resulted in gradual increase of b-wave amplitude in ERG recordings starting from the 3rd day after NalO3 administration, what confirmed the improvement of retinal function in long-term observation.

CONCLUSIONS

Our preliminary findings revealed that the selected stem cell-based therapy employed in the adjuvant mode has been shown to be effective in supporting the retinal function recovery after acute retinal damage.

Determination of arsenic in environmental and biological samples using toluidine blue or safranine O by simple spectrophotometric method

A simple spectrophotometric method has been developed for the determination of arsenic in various environmental and biological samples. The method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. This liberated iodine bleaches the blue color of toluidine blue or pinkish red color of safranine O. The decrease in absorbance at 628 or 532 nm is directly proportional to arsenic(III) concentration and obeys Beer's law in the range of 1.2-10.5 or 0.4-11.5 microg mL(-1) for arsenic(III). The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method using toluidine blue or safranine O were found to be 1.076 x 10(4) or 1.388 x 10(4) L mol(-1) cm(-1), 9.66 x 10(-3) or 7.49 x 10(-3) microg cm(-2), 0.308 or 0.250 microg mL(-1), 0.934 or 0.759 microg mL(-1) respectively. The relative standard deviation for five replicate analyses of 4 microg mL(-1) of As(III) using toluidine blue or safranine O were 0.60% or 0.80%. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described. The proposed method is free from any interference. The method has been used for the determination of arsenic in various environmental and biological samples.

An adaptive ERG technique to measure normal and altered dark adaptation in the mouse

The time-course of dark adaptation provides valuable insights into the function and interactions between the rod and cone pathways in the retina. Here we describe a technique that uses the flash electroretinogram (ERG) response to probe the functional integrity of the cone and rod pathways during the dynamic process of dark adaptation in the mouse. Retinal sensitivity was estimated from the stimulus intensity required to maintain a 30 microV criterion b-wave response during a 40 min period of dark adaptation. When tracked in this manner, dark adaptation functions in WT mice depended upon the bleaching effects of initial background adaptation conditions. Altered dark adaptation functions, commensurate with the functional deficit were recorded in pigmented mice that lacked cone function (Gnat2 ( cplf3 )) and in WT mice injected with a toxin, sodium iodate (NaIO(3)), which targets the retinal pigment epithelium and also has downstream effects on photoreceptors. These data demonstrate that this adaptive tracking procedure measures retinal sensitivity and the contributions of the rod and/or cone pathways during dark adaptation in both WT control and mutant mice.

Systemically transferred hematopoietic stem cells home to the subretinal space and express RPE-65 in a mouse model of retinal pigment epithelium damage

Stem cell regeneration of damaged tissue has recently been reported in many different organs. Since the loss of retinal pigment epithelium (RPE) in the eye is associated with a major cause of visual loss - specifically, age-related macular degeneration - we investigated whether hematopoietic stem cells (HSC) given systemically can home to the damaged subretinal space and express markers of RPE lineage. Green fluorescent protein (GFP) cells of bone marrow origin were used in a sodium iodate (NaIO(3)) model of RPE damage in the mouse. The optimal time for adoptive transfer of bone marrow-derived stem cells relative to the time of injury and the optimal cell type [whole bone marrow, mobilized peripheral blood, HSC, facilitating cells (FC)] were determined by counting the number of GFP(+) cells in whole eye flat mounts. Immunocytochemistry was performed to identify the bone marrow origin of the cells in the RPE using antibodies for CD45, Sca-1, and c-kit, as well as the expression of the RPE-specific marker, RPE-65. The time at which bone marrow-derived cells were adoptively transferred relative to the time of NaIO(3) injection did not significantly influence the number of cells that homed to the subretinal space. At both one and two weeks after intravenous (i.v.) injection, GFP(+) cells of bone marrow origin were observed in the damaged subretinal space, at sites of RPE loss, but not in the normal subretinal space. The combined transplantation of HSC+FC cells appeared to favor the survival of the homed stem cells at two weeks, and RPE-65 was expressed by adoptively transferred HSC by four weeks. We have shown that systemically injected HSC homed to the subretinal space in the presence of RPE damage and that FC promoted survival of these cells. Furthermore, the RPE-specific marker RPE-65 was expressed on adoptively transferred HSC in the denuded areas.

Monte Carlo simulation of γ-ray spectra from natural radionuclides recorded by a NaI detector in the marine environment

The GEANT4 Monte Carlo code has been used to simulate gamma-ray spectra of natural radionuclides collected by a NaI scintillation detector immersed in seawater. The gamma-rays emitted from the decay of (40)K, and the series of (232)Th and (238)U, were used to describe the radioactive water source around the NaI crystal. The simulated gamma-ray spectra were compared with real data recorded in situ by a newly constructed NaI spectrometer and were found to be in good agreement. The NaI spectrometer was calibrated in the laboratory in a water tank, before its deployment in seawater. Activity concentrations were deduced from the gamma-ray spectra and discussed in comparison with results from the literature.

Quantitative Analysis of Irbesartan in Commercial Dosage Forms by Kinetic Spectrophotometry

The objective of this work is to develop a new kinetic spectrophotometric method for the determination of irbesartan in pharmaceutical formulations. The method is based on the reaction of carboxylic acid group of the oxidized irbesartan with a mixture of potassium iodate (KIO(3)) and iodide (KI) to form yellow colored triiodide ions in aqueous medium at 30+/-1 degrees C. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 352 nm. The initial-rate and fixed-time (DeltaA) methods are adopted for constructing the calibration curves, which were found to be linear over the concentration ranges of 10.0-60.0 and 7.5-60.0 microg ml(-1) respectively. The regression analysis of calibration data yielded the linear equations: rate=-2.138 x 10(-6)+1.058 x 10(-4)C and DeltaA=-3.75 x 10(-3)+3.25 x 10(-3)C for initial rate and fixed time (DeltaA) methods, respectively. The limit of detection for initial rate and fixed time methods are 0.21 and 2.40 mug ml(-1), respectively. The various activation parameters such as E(a), DeltaH++, DeltaS++ and DeltaG++ are also calculated for the reaction and found to be 70.95+/-0.43 kJ mol(-1), 68.48+/-0.21 kJ mol(-1), 16.54+/-0.24 J K(-1) mol(-1) and -4.94+/-0.07 kJ mol(-1), respectively. The proposed methods are optimized and validated as per the guidelines of International Conference on Harmonisation (U.S.A.). The point and interval hypothesis tests have been performed which indicate that there is no significant difference between the proposed methods and the reference method. The methods have been successfully applied to the determination of irbesartan in commercial dosage forms.

Behavioral and anatomical abnormalities in a sodium iodate-induced model of retinal pigment epithelium degeneration

We characterized changes in the visual behavior of mice in which a loss of the retinal pigment epithelium (RPE) was experimentally induced with intravenous (i.v.) administration of sodium iodate (NaIO3). We compared and correlated these changes with alterations in neural retinal structure and function. RPE loss was induced in 4-6 week old male C57BL/6 mice with an i.v. injection of 1% NaIO3 at three concentrations: 35, 50, or 70 mg/kg. At 1, 3, 7, 14, 21, and 28 days (d) as well as 6 months post injection (PI) a behavioral test was performed in previously trained mice to evaluate visual function. Eye morphology was then assessed for changes in both the RPE and neural retina. NaIO3-induced RPE degeneration was both dose and PI time dependent. Our low dose showed no effects, while our high dose caused the most damage, as did longer PI times at our intermediate dose. Using the intermediate dose, no changes were detectable in either visual behavior or retinal morphology at 1 d PI. However, at 3 d PI visual behavior became abnormal and patchy RPE cell loss was observed. From 7 d PI onward, changes in retinal morphology and visual behavior became more severe. At 6 months PI, no recovery was seen in any of these measures in mice administered the intermediate dose. These results show that NaIO3 dosage and/or time PI can be varied to produce different, yet permanent deficits in retinal morphology and visual function. Thus, this approach should provide a unique system in which the onset and severity of RPE damage, and its consequences can be manipulated. As such, it should be useful in the assessment of rescue or mitigating effects of retinal or stem cell transplantation on visual function.

Retinal degeneration is delayed by tissue factor pathway inhibitor-2 in RCS rats and a sodium-iodate-induced model in rabbits

PURPOSE

To investigate the in vivo effects of tissue factor pathway inhibitor 2 (TFPI-2), which stimulates proliferation of retinal pigment epithelial cells, but not the proliferation of fibroblast and vascular endothelial cells in vitro, on retinal degeneration using a sodium-iodate (SI)-induced model in rabbits and Royal Collage of Surgeons (RCS) rats.

METHODS

79 microg of recombinant TFPI-2 (rTFPI-2) or vehicle alone was injected intravitreously to 18 eyes of 12 pigmented rabbits a day after 20 mg/kg of SI was intravenously administered. Retinal function was assessed 4, 7, 14, and 21 days after the injection by analysing amplitudes of the c-wave of a bright flash electroretinogram. Additionally, 10 microg of rTFPI-2 or vehicle alone was injected intravitreously to 11 eyes of RCS rats at both 3 and 4 weeks old, then the retina was examined histologically at 5 weeks old.

RESULTS

The rTFPI-2-treated eyes in rabbits showed a significantly less decrease in the relative amplitude of the c-wave than control eyes on days 4 and 7. The thickness of the outer nuclear layer was significantly thicker and the vacuole in the photoreceptor layer was less frequently observed in the rTFPI-2-treated RCS rats than the controls.

CONCLUSIONS

Intravitreal injection of TFPI-2 rescues SI-induced retinal degeneration in rabbits and naturally occurring retinal degeneration in RCS rats at least partly. These results may suggest that this compound can be utilized in the treatment of retinal degeneration.

Enhanced Induction of RPE Lineage Markers in Pluripotent Neural Stem Cells Engrafted into the Adult Rat Subretinal Space

PURPOSE

To investigate the differentiation of rat neural stem cells (rNSCs) into cells of retinal pigment epithelial (RPE) lineage both in vitro and in vivo, after subretinal transplantation into normal rats and in a sodium iodate (NaIO(3)) model of RPE loss.

METHODS

rNSCs prepared from the cortex of embryonic day (E)14 Fisher F344 rats were cocultured with different concentrations of vasoactive intestinal peptide (VIP), adult rat RPE cells, or neurosensory retina (NSR) for 5 days. Cell morphology and expression of RPE-specific markers (cytokeratin, CD68, microphthalmia-inducing transcription factor [MITF]) were studied. Additional antibodies used to characterize the rNSCs were markers for stem cells (nestin), immature neurons (betaIII-tubulin), astrocytes (glial fibrillary acidic protein [GFAP]), and oligodendrocytes (Rip). In in vivo studies, 10(6) green fluorescent protein [GFP]-labeled rNSCs were injected subretinally in either normal adult Lewis rats or NaIO(3)-treated rats (70 mg/mL NaIO(3) administered intravenously 7 days before transplantation).

RESULTS

In vitro VIP-treated rNSCs changed from round cells to glia-like cells with processes that stained for both GFAP and nestin. In addition, small clusters of flattened, polygonal cells with an epithelial-cell-like shape that stained for cytokeratin and CD68 were observed. Coculture of rNSCs with RPE cells, but not with NSR, also led to cells of this phenotype. After transplantation, nestin(+) and GFP(+) rNSCs were visible subretinally as a transplant. In addition, more than 50% of transplanted rNSCs were cytokeratin(+) and CD68(+).

CONCLUSIONS

Very few rNSCs differentiate in vitro into epithelial-like cells that express RPE-specific markers. In vivo, this differentiation is remarkably enhanced after subretinal engraftment. Thus, transplantation of NSCs into the subretinal space may be a therapy for retinal diseases involving an RPE abnormality.

Novel oxidative dimer from caffeic acid

The novel Diels-Alder adduct, dicaffeoyl quinone as its hydrate, was formed from the oxidation of 3,4-dihydroxycinnamic acid (caffeic acid) with NaIO4. The structure of this hydrate was determined by spectroscopic methods.

Morphologic characteristics of retinal degeneration induced by sodium iodate in mice

PURPOSE

Retinal degeneration induced by sodium iodate (NaIO( 3)) in mice was evaluated morphologically.

METHODS

Male and female ICR and C57BL mice were intraperitoneally administered 100 mg/kg NaIO(3) at 7 weeks of age, and were killed 6, 12, 24 hrs, and 3, 7 and 28 days after the treatment. Retinas were examined histologically, ultrastructurally, immunohistochemically, and by the TUNEL method.

RESULTS

Retinal degeneration was evoked in all NaIO(3)-treated mice. The primary site of damage appeared in the retinal pigment epithelial (RPE) cells followed by photoreceptor cell degeneration. Initially, the RPE cells showed necrosis starting 6 hrs post-NaIO(3), followed by photoreceptor outer segment disruption and photoreceptor cell apoptosis at 24 hrs; photoreceptor cell apoptosis peaked at day 3 and was completed by day 7. At day 3, Müller cell proliferation, macrophage migration within the retina, and regeneration of damaged RPE cells occurred. Finally at day 7 and day 28, the retina showed a mosaic pattern of relatively normal retina and areas lacking RPE cells and photoreceptor cells.

CONCLUSIONS

RPE cell necrosis followed by photoreceptor cell apoptosis and the resulting mosaic pattern of the retina phenotypically resembles gyrate atrophy of the choroid and retina.

Determination of some aminobenzoic acid derivatives: glafenine and metoclopramide

Simple, sensitive and accurate spectrophotometric methods for the determination of glafenine and metoclopramide hydrochloride are described. The first method is based on the oxidation of glafenine with iodic acid in strong acid medium to give a coloured diphenylbenzidine derivative and subsequent measurement of the coloured product at 509 nm. Beer's law is obeyed over the concentration range 2.5-20 microg ml(-1). The second method depends on the interaction of metoclopramide hydrochloride with p-dimethylaminocinnamaldehyde, to give a red coloured schiffs base with an absorbance maximum at 548 nm. Obedience to Beer's law is achieved over the concentration range 5-30 microg ml(-1). First-derivative method is used to overcome the slight interference of p-dimethylaminocinnamaldehyde reagent blank at the wavelength of measurement. Linearity between the peak heights at 576 nm versus concentration range 5-25 microg ml(-1) metoclopromide hydrochloride is obtained. The proposed methods have been successfully applied to the determination of these drugs in commercial products without interference. The validity of the methods is assessed by applying the standard addition technique, the relative standard deviation is less than 1%. The proposed methods are compared with reference methods with good agreement.

Spectrophotometry assay of imipramine and desipramine using ammonium metavanadate and its application to pharmaceutical preparations

Simple and sensitive method for determination of imipramine and desipramine is reported. The procedure is based on the oxidation of the drugs by ammonium metavanadate. Linear calibration graphs were obtained in the concentration range 0.6-40 microg ml(-1) of imipramine and 0.7-35 microg ml(-1) of desipramine with a relative standard deviation (RSD) less than 0.5%. The method was applied to the determination of the drugs in pharmaceutical preparations and compared favourably with independent official methods.

Choriocapillary changes and hyperfluorescence on indocyanine green angiography

BACKGROUND

The purpose of this study is to examine the relationship between pathological changes of the choriocapillaris (CC) and the finding of bright fluorescence on indocyanine green (ICG) angiography.

METHODS

An animal model was used, with chorioretinal lesions produced by injecting sodium iodate 3 h, 24 h, 7 days or 14 days previously. The ICG angiographic findings were compared with histology.

RESULTS

Three hours after injection, many spots of bright fluorescence were scattered at the posterior pole. Histologically, variable changes in CC endothelial cells were observed. In some regions, the cells remained almost normal morphologically. In other regions, the endothelial cytoplasm was thickened with decreased fenestrations, or precipitation of fibrin in the choroidal interstitium was observed. Twenty-four hours after injection, the area of bright fluorescence had extended beyond that observed after 3 h. Histologically, the cytoplasmic structure of CC endothelial cells was unclear, and the endothelial walls were detached from the basement membrane. When ferritin was administered as a tracer, many ferritin granules were observed in Bruch's membrane. Seven days after injection, the degree of bright fluorescence was reduced as compared with 3 and 24 h after injection. Histologically, the cytoplasm of CC endothelial cells was thinned, but contained few fenestrations. The endothelial walls were detached from the basement membrane. Fourteen days after injection, normal diffuse ICG fluorescence was observed. Histologically, CC endothelial cells exhibited almost normal structure.

CONCLUSION

These findings indicate that changes in CC endothelial cells and bright fluorescence on ICG angiography are closely related. ICG angiography should enable clinical evaluation of increased permeability of CC endothelial cells to relatively large molecules.

Effect on infant mortality of iodination of irrigation water in a severely iodine-deficient area of China

BACKGROUND

Hotien county in Xinjiang province, China, is an area of severe iodine deficiency and has a high infantmortality rate. We investigated whether iodine replacement through iodination of the irrigation water would decrease infant mortality.

METHODS

We added potassium iodate to irrigation water over a 2 to 4 week period beginning in 1992 in certain areas of three townships (Tusala, Long Ru, and Bakechi). Logistic regression analysis was used to compare the odds ratios for infant and neonatal mortality in treated and intreated areas.

FINDINGS

The median urinary iodine concentration significantly increased in women of child-bearing age from < 10 micrograms/L to 55 micrograms/L. Infant-mortality rates decreased in the treated areas of Long Ru (mean [SD] 58.2 [4.4] per 1000 births to 28.7 [7.1] per 1000 births), Tusala (47.4 [12.4] per 1000 births to 19.1 [1.5] per 1000 births), and Bakechi (106.2 [9.5] per 1000 births to 57.3 [7.3] per 1000 births). Similar results were also seen for neonatal mortality. On regression analysis iodine treatment and time were significant independent predictors of infant mortality.

INTERPRETATION

Iodine supplementation of irrigation water in areas of severe iodine deficiency decreases neonatal and infant mortality. Iodine replacement has probably been an important factor in the national decrease in infant mortality in China.

Reactive liposomes encapsulating a glucose oxidase-peroxidase system with antibacterial activity

Liposomes were prepared from phospholipid mixtures of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylinositol (PI), encapsulating the enzymes glucose oxidase (GO) and GO in combination with horse radish peroxidase (HRP) by both extrusion (VET) and reverse-phase evaporation (REV). The optimum level of PI in DPPC/PI liposomes for targeting to biofilms of the oral bacterium Streptococcus gordonii has been established. The liposomes were characterised in terms of the content and activity of the encapsulated enzymes. The antibacterial activity of these 'reactive' liposomes arising from hydrogen peroxide and oxyacids in the presence of the substrates glucose and iodide ions, after targeting to the biofilms, were measured both as a function of liposome-biofilm incubation time and incubation time with the substrates. Bacterial inhibition increases with both liposome-biofilm and substrate-biofilm incubation time and with the extent of enzyme encapsulation. The reactive liposomes also display antibacterial activity in the presence of saliva. The reactive liposomes have potential value in the context of oral hygiene.