Comparative studies on the distribution of gold, copper and zinc in the livers and kidneys of rats and hamsters after treatment with sodium [195Au]-aurothiomalate

First Evaluation of a Retinal Imaging Laser Eyewear System Based Low Vision Aid

Purpose

We conducted this trial to investigate a new wearable laser-eyewear (LEW). Images of an integrated camera are projected to the retina by a RGB-Laser (<1µW) and MEMS-mirror system. This enables a full-color live video as augmented reality embedded in the field of vision of the wearer. Thin parallel laser beams are projected following the principle of Maxwellian view through the center of the ocular lens to ensure independency of refractive errors. We performed a study with healthy subjects to test this independency.

Materials and Methods

LEW was tested in 20 healthy subjects (aged between 21 and 60 years) with hyperopia, myopia, astigmatism and/or presbyopia. Subjects underwent standardized visual acuity (VA) measurements (ETDRS) without any correction, with LEW and with best correction.

Results

We found no significant correlation between refraction and VA while using LEW in linear regression (r=0.17). Still, younger participants performed better in terms of VA with the device compared to older participants despite no differences in BCVA (p<0.01). The achievable VA with LEW was in general reduced compared to uncorrected VA (0.50 vs 0.40 logMAR). Only myopic subjects reached a significantly higher VA using LEW (p<0.001). Presbyopic subjects showed enhanced near VA (0.25 logMAR) by reading at 15cm with LEW without any further necessary refractive correction. Nearly all patients (80%) showed stereopsis without need for additional adjustments.

Conclusion

Our investigation could verify the independence of LEW of refractive errors. Therefore, the technology seems to be especially useful in patients with untreatable corneal conditions, e.g., after corneal burns, to achieve higher VA since the thin laser should penetrate even corneal opacities with less scattering.

Localization of the induced metallothionein and DNA damage in rat kidney after gold injection

To clarify the relationships between DNA damage and Cu-MT and between DNA damage and Cu in kidneys of rats injected with Au, we examined the histochemical localization of DNA damage, metallothionein (MT), and the accumulated Cu in the kidneys of rats injected with Au, Cu, or Cu-MT. The immunoreactivity of MT was observed predominantly in the outer stripe of the outer medulla and the inner cortex of the Au-injected rat, and the signals of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) were observed in the cortex. Cu detected by Timm's method was mainly distributed in the cortex of the Au-injected rat. These results indicated that DNA damage could be caused by free Cu in the cortex but not by the Cu bound to MT in the outer stripe of the outer medulla. This consideration was supported by the data from rats injected with Cu and Cu-MT. Furthermore, we determined the Cu contents in three fractions (cytosol, organelle, and precipitate-containing nuclei) of the kidneys. Interestingly, most of the Cu content in the kidney of the rat injected with Au or Cu-MT was detected in the cytosol, whereas most of the Cu content in the kidney of the rat injected with Cu was detected in the nuclei-containing precipitate. These findings suggest that the DNA damage in the kidneys of rats injected with Au may be associated with Cu-binding proteins but not with Cu-MT.

The effect of Au injection on the ceruloplasmin, metallothionein and 8-hydroxydeoxyguanosine of rat serum, kidney and liver

The present study was carried out to investigate the effect of gold (Au) injection on copper (Cu) and two types of ceruloplasmin (Cp), total Cp (ID1) and active Cp (ID2), metallothionein (MT) in the serum, kidney and liver, and 8-hydroxydeoxyguanosine (8-OHdG) in the rat kidney. The Cu contents in sera and kidneys of Au-injected rats were 1.7 and 5.5 times higher than those in sera and kidneys of control rats, respectively. The most of Cu in the sera of the control rats or Au-injected rats were observed in the Cp fractions from a Sephacryl S-200 column. The Cu concentration in the Cp fractions was increased by Au injection. Significant increases of ID1 and ID2 were found in the sera of the control rats and Au-injected rats, while there was no significant difference in those concentrations of livers or kidneys between the control rats and Au-injected rats. Our results indicated that the most of Cp existed as active ID1. The immunoreactivity of 8-OHdG was located in the cortex of the Au-injected rat. These results indicated that the oxidative DNA damage occurred in the renal cortex of the Au-injected rat and the localization of DNA damage did not coincide with that of Cu-MT. These findings suggest that the oxidative DNA damage in the kidneys of rats injected with Au is associated with Cu except Cu-MT.

Influences of gold on zinc, copper and metallothionein kinetics in liver and kidney of the rat

1. Single, very low dose of gold (500 micrograms/kg body weight) was given intramuscularly to male Sprague-Dawley rats (mean body weight: 200 g) as aurothiokeratinate (Auro-Detoxin(R) dissolved in 0.9% NaCl. 2. Blood, liver and kidney were samples at autopsy 0.5, 1, 2, 3, 6 and 12 h after the gold injection (six animals per time). 12 rats were treated with 0.9% saline only as controls. The zinc (Zn), copper (Cu), gold and metallothionein (MT) concentrations were determined in homogenates and cytosols of liver and kidney using atomic absorption spectrometry and gel chromatography, respectively. 3. The main changes in metal and MT concentrations occurred in the kidney, where an increase of gold was found 0.5 h after the injection, followed by an increase in Cu and MT concentrations after 6 h. Zn homeostasis did not change. 4. The results suggest that gold by itself induces an increase of MT-like peptides in the kidney cytosol, which was accompanied by an increase in the concentration of Cu mainly bound to these MT-like peptides.

Renal binding of cadmium in the rat following intragastric exposure

Renal binding of cadmium was compared in groups of rats administered cadmium intragastrically or subcutaneously in doses resulting in similar renal cadmium concentrations. In rats administered cadmium intragastrically the renal concentrations of copper and metallothionein were lower, suggesting disturbance in copper metabolism. These changes were alleviated gradually in the post-exposure period. In experiments with 64Cu it has been shown that intragastric exposure to cadmium reduced copper absorption to about 21% of that in the control rats, thus explaining the poor copper availability for renal binding of cadmium in the form of Cd,Cu-metallothionein. Changes in zinc uptake were less strongly marked and were limited to slight decrease of zinc content in the kidneys.

Metallothionein in cultured human epithelial cells and synovial rheumatoid fibroblasts after in vitro treatment with auranofin

Radioimmunoassay (RIA) and reversed-phase high-pressure liquid chromatography (HPLC) were used to investigate gold-binding proteins of possible metallothionein (MT) nature occurring upon auranofin exposure of cultured human cells. An epithelial cell line (HE) and two sub-strains were examined. The HEAF sub-strain had been made resistant to 2 mumole auranofin/l culture medium. The resistance was associated with the appearance of gold-binding substances with gel filtration characteristics like MT. The HE100 sub-strain had been made resistant to 100 mumole CdCl2/l and contained high amounts of cytosolic Cd-induced MT. In addition, cultured synovial fibroblasts, derived from normal (SN) and rheumatoid (SRA) synovial tissues, were investigated. Evidence was obtained by RIA that the low molecular weight (mol.wt. 6000-7000) gold-binding proteins occurring in the HEAF cells and SRA cells following auranofin exposure, were of MT nature. The relative amounts of MT in the epithelial cell lines were: HE:HEAF:HE100 = 1:18:100. The relative amounts in the synovial fibroblasts were: SN:SRA:SRA treated with auranofin = 1:3:10. The HPLC methods used were found suitable for isolation of Cd-MT in the HE100 cells, but not for the Au-MT in the HEAF cells. By HPLC, the Cd-MT in the HE100 cells was resolved into 3 MT-1 and 1 MT-2 iso-proteins exhibiting the amino acid composition typical of MT. Judged by HPLC, the MT in these cells constituted 0.4% of the cytosolic proteins.

Cultured human cells with high levels of gold-binding cytosolic metallothionein are not resistant to the growth inhibitory effect of sodium aurothiomalate

We have previously shown that cells with a high content of the gold-binding protein metallothionein (MT) are resistant to the growth inhibitory effects of gold(III) chloride and auranofin. To investigate whether MT confers resistance to sodium aurothiomalate two cell lines of cultured human epithelial (HE) cells were used; the parental cell line (HE) and a substrain (HE100) containing high levels of cytosolic MT. Sodium aurothiomalate and thiomalic acid without gold both caused a dose-dependent growth inhibition of both cell lines when used in the concentration range 25-300 mumol/l culture medium and for four days' exposure. MT, despite binding about one third of the cytosolic gold, did not protect against the antiproliferative effect of sodium aurothiomalate. The gold and the thiomalate moieties were distributed differently within the cells; 30% of the cellular gold and 80% of the thiomalate were recovered in the cytosol. Gold was mainly protein bound in both cell lines, as shown by G75 Sephadex gel filtration of the cytosols. In the HE100 cells about 30% of the gold eluted with MT. The thiomalate eluted mainly with substances with molecular weights less than 1000. Cellular synthesis of MT was not observed during sodium aurothiomalate treatment. The results indicate that the sodium aurothiomalate molecule dissociates and support the suggestion that the thiomalate moiety is, in part, responsible for the antiproliferative effect of the drug.

Auranofin treatment of rats: adaptation to intestinal adverse effects and observations on the cytosolic distribution of gold in the intestines, liver and kidneys

The possibility of development of adaptation to intestinal adverse effects of auranofin (AF), a gold-containing anti-arthritic drug, was investigated in rats. Groups of 6 rats received orally 0.0, 2.5 or 10.0 mg AF/kg daily for one week, and 20.0 mg AF/kg daily the next week. During the first week all animals had normal stools. During the second week, those on 0.0 or 2.5 mg AF/kg the preceding week developed persistent loose stools, whereas those on 10.0 mg AF/kg the preceding week did not. At the end of the second week, no differences in the intestinal cytosolic gold concentrations were detected, which could be related to the dose regimen or the loose stools. Gel filtration profiles of gold from intestinal, liver and kidney cytosols following AF treatment, were compared with gold profiles following in vitro incubation of AF with cytosols obtained from non-treated rats. In the in vivo situation, but not in vitro, gold peaked with proteins of mol. wt. about 10,000 in the small intestine and kidneys. Up to 20% of the cytosolic gold was recovered in these fractions in the small intestine. These proteins eluted slightly different from metallothionein on gel filtration. The cellular mechanisms involved in the demonstrated adaptation to intestinal adverse effects from AF, are not clear, judged from the present study.

Time-dependent uptake and metallothionein-binding of gold, copper and zinc in the rat kidney

In rats, in which the whole body burden of Au decreases rapidly, but biphasically, maximum kidney concns are not attained until 10-15 days after a single intraperitoneal dose of either Au(I) or Au(III). The concn of metallothionein-bound Au and of total kidney Cu, which also increases after the administration of the Au compounds, however, reach maxima at 5 days. Between at least 6 and 24 hr after Au treatment, the increases in the concn of Au and Cu in the metallothionein fraction are highly correlated. Measurements on the kidneys of animals at early times (15 min-6 hr) after dosing with Au(III) indicate that the Zn content of the (endogenous) metallothionein is depressed during the first hour, shows a transient increase at 2 hr and then falls to a minimum at 6 hr. Subsequent (6-24 hr) changes in metallothionein-bound Zn parallel those of metallothionein-bound Au and Cu. It seems, therefore, that Au and Cu are incorporated simultaneously into rat kidney metallothionein and this incorporation may be mediated by an initial displacement of Zn. In rats exposed to five doses of Au(III) the half-times of total and metallothionein-bound Au in the kidneys are appreciably longer than those in animals given a single dose. In both groups, the concns of Cu and Zn in the renal metallothionein do not decrease in parallel with that of Au, but change roughly in proportion to their whole kidney concns. In consequence, the metal composition of the metallothionein fraction, which remains above the endogenous concn in the normal kidney throughout an experimental period of 90-140 days, alters considerably with time.

The effects of cadmium and copper on the renal uptake and metallothionein binding of gold in the rat and hamster

Rats and hamsters, (pre)-treated with copper and cadmium, were used to investigate whether species-differences in renal metallothionein synthesis in response to gold were determined by changes in the kidney concentrations of other metals. The effects of both dietary copper limitation and excess on the renal metabolism of gold also were studied in the rat. In this species, all of the pre-treatments affected the renal concentrations of total and metallothionein-bound copper, but none of them altered either the kidney uptake or thionein-binding of gold. Incorporation of zinc into the metallothionein, which accompanied the binding of gold in this fraction of the kidney, however, was influenced slightly by the pretreatments, In hamsters, pretreatment with cadmium, which increased the concentrations of total and thionein-bound zinc in the kidneys, also did not affect the renal uptake of gold, although it increased significantly the binding of gold to the metallothionein fraction of the renal cytosol. This increased binding of gold also was accompanied by further increases in the zinc and copper contents of the metallothionein; the contents of total and thionein-bound cadmium, however, remained essentially unchanged. Concentrations of copper and zinc in the hamster kidney were not affected significantly by subcutaneous administration of copper alone (five daily doses, each of 3.2 mg Cu/kg body wt.), but were increased when gold was given during the copper-treatment. The concentrations of gold, copper and zinc in the renal metallothionein fraction also were increased under these conditions. From these results it seems that kidney metallothionein synthesis in response to gold may be related to the changes in either the concentration or distribution of zinc, rather than copper.