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Murine cytomegalovirus (MCMV) spreads to and replicates in the retina after endotoxin-induced disruption of the blood-retinal barrier of immunosuppressed BALB/c mice.

The goal of this study was to determine whether disruption of the blood-retinal barrier (BRB) facilitates spread of MCMV to the retina in immunosuppressed (IS) BALB/c mice. IS mice were inoculated intravenously (i.v.) with murine cytomegalovirus (MCMV) or with macrophages infected with MCMV for 4 days in vitro. The BRB was disrupted by injection of sodium iodate (i.v.) or lipopolysaccharide (LPS, i.v. or anterior chamber). Frozen sections of ocular tissue were examined for MCMV antigens. The results showed that MCMV-infected cells were observed only in the choroid and ciliary body in IS mice with an intact BRB. After LPS injection, a few positive cells were observed in the retina of IS mice after i.v. injection of MCMV. In lipopolysaccharide (LPS)-treated IS mice, a few PKH-26-positive macrophages or MCMV-positive cells were observed in the retina at 1 or 2 days after injection of macrophages. No PKH-26-positive cells or virus-infected cells were noted in the retina of phosphate-buffered saline (PBS)-treated mice. Ten days after injection of virus-infected macrophages, MCMV-infected cells were observed in choroid and ciliary body of both LPS- and PBS-treated mice, but they were observed in the retina only in LPS-treated mice. The results support the idea that disruption of the BRB allows MCMV to spread to the retina of IS mice and that monocytes/macrophages disseminate MCMV to the retina in mice with a disrupted BRB. By extrapolation, damage to the BRB in immunosuppressed patients may facilitate spread of CMV-infected monocytes/macrophages to the retina.

Animals↗

The role of glutathione in DNA damage by potassium bromate in vitro.

We have investigated the role of reduced glutathione (GSH) in the genetic toxicity of the rodent renal carcinogen potassium bromate (KBrO(3)). A statistically significant increase in the concentration of 8-oxodeoxyguanosine (8-oxodG) relative to deoxyguanosine was measured following incubation of calf thymus DNA with KBrO(3) and GSH or N-acetylcysteine (NACys). This was dependent on these thiols and was associated with the loss of GSH and production of oxidized glutathione. A short-lived (<6 min) intermediate was apparent which did not react with the spin trap dimethylpyrroline N-oxide. DNA oxidation was not evident when potassium chlorate (KClO(3)) or potassium iodate (KIO(3)) were used instead of KBrO(3), though GSH depletion also occurred with KIO(3), but not with KClO(3). Other reductants and thiols in combination with KBrO(3) did not cause a significant increase in DNA oxidation. DNA strand breakage was also induced by KBrO(3) in human white blood cells (5 mM) and rat kidney epithelial cells (NRK-52E, 1.5 mM). This was associated with an apparent small depletion of thiols in NRK-52E cells at 15 min and with an elevation of 8-oxodG at a delayed time of 24 h. Depletion of intra-cellular GSH by diethylmaleate in human lymphocytes decreased the amount of strand breakage induced by KBrO(3). Extracellular GSH, however, protected against DNA strand breakage by KBrO(3), possibly due to the inability of the reactive product to enter the cell. In contrast, membrane-permeant NACys enhanced KBrO(3)-induced DNA strand breakage in these cells. DNA damage by KBrO(3) is therefore largely dependent on access to intracellular GSH.

8-Hydroxy-2'-Deoxyguanosine↗

The relationship between the c-wave and light response of the rabbit eye.

The rabbit c-wave and light response (LR) of the standing potential were recorded simultaneously while presenting the eye with light flashes at 15 sec intervals. The LR peaked about 15 min after the onset of flashes, but the c-wave amplitude remained constant after the first min of stimulation. Elimination of pigment epithelial activity with intravenous sodium iodate blocked both the c-wave and LR. Elimination of inner retinal activity with intravitreal aspartic acid blocked neither. These results are consistent with those from other mammals insofar as the pigment epithelium is required for both c-wave and LR, but differ from other species in two respects: (1) the rabbit LR is not sensitive to aspartate; (2) the rabbit c-wave does not vary in amplitude with the LR.

Animals↗

Postnatal maldevelopment of the retina.

The effect of certain factors on the early postnatal development of the retina was studied by electron microscopy. Although the retina of developing rats injected with sodium iodate on the 1st and 7th postnatal days showed no retardation of development of photoreceptor outer segment, it began to degenerate about 3 weeks after birth. The retina of developing rats exposed to strong light from the 1st to 5th postnatal day revealed slight developmental retardation of the photoreceptor outer segment and the photoreceptor outer segment began to degenerate about 3 weeks after birth. The vitamin A deficient developing rat it began to degenerate nearly 3 weeks after birth. In spite of induction of developmental retardation of the photoreceptor outer segment of the retina, development of the photoreceptor outer segment was not completely inhibited by moderately acting factors. However, 3 weeks after birth, the photoreceptor outer segments began to degenerate. Therefore, some factors during the early postnatal period can cause the late appearance of degeneration of the retina. The characteristics of retinal degeneration are the same as those found in the retinas of adult rats which are affected by each factor. These degenerations later recover morphologically.

Animals↗

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.

Animals↗

Bone marrow-derived cells home to and regenerate retinal pigment epithelium after injury.

PURPOSE: To determine whether hematopoietic stem and progenitor cells (HSCs/HPCs) can home to and regenerate the retinal pigment epithelium (RPE) after induced injury. METHODS: Enriched HSCs/HPCs from green fluorescent protein (gfp) transgenic mice were transplanted into irradiated recipient mice to track bone marrow-derived cells. Physical damage was induced by breaching Bruch's membrane and inducing vascular endothelial growth factor A (VEGFa) expression to promote neovascularization. RPE damage was also induced by sodium iodate injection (40 mg/kg) into wild-type or albino C57Bl/6 mice. Cell morphology, gfp expression, the presence of the Y chromosome, and the presence of melanosomes were used to determine whether the injured RPE was being repaired by the donor bone marrow. RESULTS: Injury to the RPE recruits HSC/HPC-derived cells to incorporate into the RPE layer and differentiate into an RPE phenotype. A portion of the HSCs/HPCs adopt RPE morphology, express melanosomes, and integrate into the RPE without cell fusion. CONCLUSIONS: HSCs/HPCs can migrate to the RPE layer after physical or chemical injury and regenerate a portion of the damaged cell layer.

Adenoviridae↗

Retinal pigment epithelium damage enhances expression of chemoattractants and migration of bone marrow-derived stem cells.

PURPOSE: To characterize chemoattractants expressed by the retinal pigment epithelium (RPE) after sodium iodate (NaIO3)-induced damage and to investigate whether ocular-committed stem cells preexist in the bone marrow (BM) and migrate in response to the chemoattractive signals expressed by the damaged RPE. METHODS: C57/BL6 mice were treated with a single intravenous injection of NaIO3 (50 mg/kg) to create RPE damage. At different time points real-time RT-PCR, ELISA, and immunohistochemistry were used to identify chemoattractants secreted in the subretinal space. Conditioned medium from NaIO3-treated mouse RPE was used in an in vitro assay to assess chemotaxis of stem cell antigen-1 positive (Sca-1+) BM mononuclear cells (MNCs). The expression of early ocular markers (MITF, Pax-6, Six-3, Otx) in migrated cells and in MNCs isolated from granulocyte colony-stimulating factor (G-CSF) and Flt3 ligand (FL)-mobilized and nonmobilized peripheral blood (PB) was analyzed by real-time RT-PCR. RESULTS: mRNA for stromal cell-derived factor-1 (SDF-1), C3, hepatocyte growth factor (HGF), and leukemia inhibitory factor (LIF) was significantly increased, and higher SDF-1 and C3 protein secretion from the RPE was found after NaIO3 treatment. A higher number of BMMNCs expressing early ocular markers migrated to conditioned medium from damaged retina. There was also increased expression of early ocular markers in PBMNCs after mobilization. CONCLUSIONS: Damaged RPE secretes cytokines that have been shown to serve as chemoattractants for BM-derived stem cells (BMSCs). Retina-committed stem cells appear to reside in the BM and can be mobilized into the PB by G-CSF and FL. These stem cells may have the potential to serve as an endogenous source for tissue regeneration after RPE damage.

Animals↗

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.

Algorithms↗

A simple and sensitive analytical method for the determination of antimony in environmental and biological samples.

The results of a study and application of leucocrystal violet for the determination of antimony in parts per million levels is described here. The proposed method is based on the reaction of antimony(III) with acidified potassium iodate to liberate iodine. The liberated iodine selectively oxidizes leucocrystal violet to crystal violet dye. The formed dye shows maximum absorbance at 590 nm. The color system obeys Beer's law in the concentration range from 0.4 - 3.6 microg antimony per 25 ml of final solution. The molar absorptivity and Sandell's sensitivity were found to be 7.32 x 10(5) l mol(-1) cm(-1) and 0.0016 microg cm(-2), respectively. All variables were studied in order to optimize the reaction. The proposed method is satisfactorily applicable for the analysis of antimony in various environmental and biological samples. The method is simple, highly sensitive, accurate and reliable.

Antimony↗

Electrical responses of the rat's retinal pigment epithelium to azide and thiocyanate.

In the rat under urethane anesthesia, a fast intravenous injection of a bolus of sodium azide elicited a transient cornea-positive change in transocular potential (azide response). A bolus injection of sodium thiocyanate (NaSCN) produced a cornea-negative response (SCN- response) with a similar rising phase as the azide response, but with a faster return from the peak. The peak amplitude depended on bolus volume, concentration, animal strain, and age. For more than 24 h, the azide and SCN- responses could be recorded repeatedly from a single rat with little variation in peak amplitudes. Following an administration of iodate, known to degenerate the retinal pigment epithelium (RPE), the transocular d.c. potential decreased; the azide response became smaller and then was inverted in polarity, whereas the SCN- response became larger. Azide and SCN- are assumed to depolarize and hyperpolarize the basal membrane of RPE, respectively. The equilibrium potential of ions passing through the putative azide-sensitive channels is assumed less negative than resting potential of RPE cells. The SCN- response probably represents a diffusion potential of SCN- permeating through anionic channels at a higher rate than Cl-. Results demonstrate the feasibility of in vivo electrophysiological measurement of the functional state and the structural integrity of RPE under pathological conditions.

Animals↗

A quick-mixed aluminum hematoxylin stain.

Two stock solutions are composed as follows: A) aluminum sulfate, sodium iodate and acetic acid in aqueous propylene glycol and B) hematoxylin in pure propylene glycol. When combined in specified proportions the stock solutions yield aluminum-hematein dissolved in nontoxic propylene glycol. The ready-to-use stain, prepared in small volumes as needed, performs well in paraffin sections of plant tissues.

Acetates↗

Influences of stable iodine upon the concentration of radioactive iodine by marine organisms.

Uptake and loss of radioactive iodine by marine organisms were studied in the artificial seawater in which the concentration as well as chemical forms of both stable and radioactive iodine were controlled. The concentration factors of radioactive iodine by these organisms were clearly dependent upon the concentration of stable iodide ion in the culture media while the concentration of stable iodate ion did not affect the uptake and loss of radioactive iodine. It was observed that the higher the concentration of iodide ion was in the culture media the shorter the biological half-life of radioactive iodine became, and thus the lower the concentration factor resulted in.

Animals↗

Screening of antiadherent activity on Streptococcus sobrinus culture.

The mutans group of streptococci is considered to play a key role in the etiology of dental caries. We have evaluated the ability of different substances to prevent dental plaque formation without affecting Streptococcus sobrinus viability. Viable organisms were detected as CFU/mL in agar plates and bacterial adherence was assessed by dry weight. We studied 23 compounds and we demonstrated that phenyl salicylate, phenylmercuric nitrate and potassium iodate are more effective to inhibit adhesion without showing antibacterial activity.

Anti-Infective Agents, Local↗

Preparation of iodized salt for goitre prophylaxis.

The methods employed for iodizing free-running salts are discussed. They are not suitable for the iodization of coarse crystalline salts and a new process has been devised by the Chilean Iodine Educational Bureau of London for the iodization of open-pan and solar evaporated salts. This process is described and illustrated by photographs of suitable plants. Attention is drawn to the advantages of potassium iodate as an iodizing agent.

Chile↗

Endemic goitre in Basutoland. Report on a survey.

Although it has long been known that endemic goitre exists in Basutoland, there was no clear information on its prevalence until a survey, reported on here, was conducted in 1957-58 by a nutrition survey team sent by the World Health Organization at the request of the Basutoland Government. Seven of the nine districts were covered by this survey, which revealed an average prevalence of endemic goitre (mainly diffuse) of 41%, with a range of from 30% to 50% according to the district. The problem is thus clearly a serious one, and the authors recommend the use of salt iodized at a level of 1 part of potassium iodate in 10 000-20 000 parts of salt.

Goiter↗

[Preparation of Harris hematoxylin without use of mercury oxide].

The study was carried out with the aim of improvement of Harris' alum hematoxylin formula. In presented modified formula toxic mercuric oxide (2.5 g) is substituted by potassium iodate (0.55 g). Alum hematoxylin solution prepared according to suggested formula retains high quality of original Harris' hematoxylin.

Glycerol↗

Accurate and precise measurement of blood-retinal barrier breakdown using dynamic Gd-DTPA MRI.

Dynamic T1-weighted magnetic resonance imaging (MRI) after the injection of Gd-DTPA is a promising method for investigating breakdown of the blood-retinal barrier (BRB). Previously, the authors demonstrated that in a T1-weighted image, the initial rate of change in the vitreous water MRI signal as gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) enters the vitreous space strongly correlated with the extent of BRB breakdown. Here, a practical approach to measuring a more relevant physiologic parameter is presented: the permeability surface area product (PS). The theory is a development of earlier work used in investigating the breakdown of the blood-brain barrier. The accuracy and precision of this approach was investigated in rabbits pretreated with sodium iodate (30 mg/kg intravenously). The MRI-derived PS normalized to the area of leaky retina (5.65 +/- 0.25 x 10(-4) cm/min, mean +/- standard error of the mean; n = 6) was compared to a similarly normalized PS calculated using a classical physiologic method (4.12 +/- 0.73 x 10(-4) cm/min; n = 6). Good agreement between the two methods was found (P = 0.09). This result demonstrates that the MRI-derived PS is an accurate and precise measure of BRB breakdown under these conditions. The mathematical model of Gd-DTPA distribution in vivo also is validated. Based on these results, several potential sources of error are discussed, including the effect of back-flow of Gd-DTPA from the vitreous space to the plasma, the underlying vascular patency, and MRI slice selection.

Animals↗

Prevention of endemic goitre with iodized salt.

The paper describes a study, carried out over 16 years, of the use of iodized salt for the control of endemic goitre in a valley of the Himalayan foothills. From 1956, salt was fortified with either potassium iodide or potassium iodate to provide an estimated daily intake of 200 mug per head. There was a progressive and significant decline in goitre prevalence, together with a return of the pattern of iodine metabolism to within normal limits. It is concluded that endemic goitre can be successfully controlled by iodization of domestic salt.

Adolescent↗