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PubMed1997

Protective effect of deferoxamine on chromium (VI)-induced DNA single-strand breaks, cytotoxicity, and lipid peroxidation in primary cultures of rat hepatocytes.

Incubation of primary cultures of rat hepatocytes with K2CR2O7 and deferoxamine (DFO), an iron chelator, resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K2Cr2O7. Cellular treatment with DFO also suppressed both dichromate-induced cytotoxicity--evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation--as monitored by malondialdehyde formation. In addition, treatment with DFO attenuated the suppression of the levels of vitamin E and C as well as the inhibition of alkaline phosphatase and glutathione peroxidase activity attributed to K2Cr2O7. However, DFO had no influence on the cellular level of glutathione or the activity of glutathione reductase and superoxide dismutase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of chromium were not affected by DFO. These results indicate that DFO protects cells from chromium (VI)-induced DNA strand breaks, cytotoxicity, lipid peroxidation, vitamin E and C depression, and glutathione peroxidase inhibition The role of antioxidants in chromium (VI)-induced cytotoxicity, DNA breaks, and lipid peroxidation is discussed.

Alkaline Phosphatase↗
PubMed2000

Microstructural analysis of severe bone lesions in seven thalassemic patients treated with deferoxamine.

Osteochondrodystrophic lesions, mainly affecting long bone metaphyses, can be radiologically evident in homozygotic thalassemic patients treated with deferoxamine, and their incidence rate varies among authors. The clinical and radiological appearance of these lesions is described in the literature, but microstructural data are still lacking. The aim of our research was to evaluate the microstructure of five tibial biopsy specimens from thalassemic patients with bone lesions (5 cases out of 180 patients followed for the last 10 years, i.e., 2.8%) and two bone biopsy specimens from thalassemic patients with no radiological alteration of the long bones. As control, bone tissue taken from autoptic tibiae of two subjects with no skeletal pathology was used. Using microradiography and X-ray diffraction (XRD), we found a reduced and irregular mineralization of the bone (compared with controls) in thalassemic subjects. Bone tissue microhardness was also significantly reduced. Nevertheless, bone apatite lattice was unaltered and no 'foreign' crystallographic phase was recorded by XRD. In conclusion, all the patients shared a similar picture of abnormal bone, even with no radiological evidence of lesion.

Adolescent↗
PubMed2003

Deferoxamine reduces and nitric oxide synthase inhibition increases neutrophil-mediated myotube injury.

We tested the contribution of reactive oxygen species (ROS), reactive nitrogen species (RNS) and the beta 2 integrin CD18 to neutrophil-mediated myotube injury. Human myotubes were cultured with human neutrophils in the presence or absence of inhibitors directed against ROS, RNS, and CD18. Muscle injury was assessed by a (51)Cr release assay. The inclusion of superoxide dismutase (50-500 U/ml) in the culture medium did not affect myotube injury. A significant protective effect was provided by including catalase (600-2400 U/ml), deferoxamine (1-2 mM), or anti-CD18 antibody (10 microg/ml) in the culture medium. S-Ethylisothiourea (500-1000 microM), an inhibitor of nitric oxide synthase (NOS), significantly increased myotube injury and reduced nitric oxide (NO) in cultures consisting of only myotubes. In conclusion, neutrophil-mediated skeletal muscle injury appears to be largely dependent on CD18-mediated neutrophil adhesion and iron-dependent hydroxyl radical production. In addition, skeletal muscle NOS activity may protect skeletal muscle against the injury caused by neutrophils.

CD18 Antigens↗
PubMed1992

Preparation of iron-deficient tissue culture medium by deferoxamine-sepharose treatment and application to the differential actions of apotransferrin and diferric transferrin.

We have shown that triiodothyronine-dependent GH1 rat pituitary cell growth in serum-free defined culture required apotransferrin (apoTf) (D. A. Sirbasku, et al., Biochemistry 30, 295-304, 7466-7477, 1991). These studies were done in "low-Fe" medium without Fe(III)/Fe(II) salts. Nonetheless, significant concentrations of iron may have been contributed by other components, making this medium unsuitable for study of the differential effects of apoTf and diferric transferrin (2Fe.Tf). Measuring residual iron in culture medium has been troublesome because the most sensitive method (i.e., atomic absorption) detected levels only in excess of 10 ng/ml and did not distinguish between the forms of iron present. To estimate the Fe(III) available to bind to apoTf, we developed a more sensitive and specific method. Urea-polyacrylamide gel electrophoresis (PAGE) separates apoTf, the two monoferric transferrins, and 2Fe.Tf. [125I]apoTf was incubated with medium, or components, and the formation of [125I]-2Fe.Tf was monitored by urea-PAGE/autoradiography. By this method, the concentration of Fe(III) in low-Fe medium was estimated at 8.4 to 20 ng/ml and the sources were identified. We next sought to remove the Fe(III). Standard chelators were ineffective or cytotoxic. In contrast, an affinity method with deferoxamine-Sepharose depleted greater than or equal to 90% of the Fe(III). In this medium, apoTf and 2Fe.Tf showed differential effects with GH1 cells and with MCF-7, MTW9/PL2, an MDCK cells. With the methods described here, the effects of apoTf and 2Fe.Tf on growth can be studied separately.

Animals↗
PubMed1990

Mechanism of protection of alveolar type II cells against paraquat-induced cytotoxicity by deferoxamine.

Paraquat toxicity has been associated with the generation of free radicals in alveolar epithelial cells in which paraquat specifically accumulates via a polyamine uptake system. In the present study we investigated whether deferoxamine (DF), an iron chelator that has antioxidant capacity and that also has a polyamine-like structure, could protect alveolar type II cells (ATTC) against injury by paraquat. Radiolabeled [3H]adenine ATTC were incubated in a medium containing 75 microM paraquat in the absence or presence of DF (500 microM). After 3 hr of incubation paraquat-mediated cytotoxicity of ATTC, as measured by [3H]adenine release, was significantly (P less than 0.005) decreased by addition of DF (26.6 +/- 2.6% vs 7.4 +/- 1.7%). Accumulation of radiolabeled [14C]paraquat at a concentration of 75 microM was also decreased (70%) by 500 microM DF from 94.8 +/- 2.1 to 28.9 +/- 6.7 nmoles paraquat/2.5 x 10(5) ATTC. This effect of DF was dose dependent and comparable with the protective effect of equimolar concentrations of putrescine. However, per cent uptake of paraquat at a concentration of 500 microM was not significantly inhibited by DF (1 mM), whereas paraquat-induced injury was still markedly reduced (36.2 +/- 2.5% vs 2.6 +/- 4.2%). This indicated that the protective effect of DF could not be explained by its competition with paraquat on uptake alone. In the same series of experiments using another iron chelator, pyridoxal benzoyl hydrazone (PBH), which has antioxidant properties similar to DF but does not show its polyamine-like structure, ATTC lysis was also prevented although paraquat uptake was not reduced. These in vitro data indicate that the mechanism of protection by DF against paraquat toxicity in lung epithelial type II cells is two-fold: inhibition of paraquat uptake through its compliance with the structural requirements necessary for transport, and inhibition of paraquat-induced iron-catalysed free radical generation.

Animals↗
PubMed1991

Role of iron in T cell activation: TH1 clones differ from TH2 clones in their sensitivity to inhibition of DNA synthesis caused by IgG Mabs against the transferrin receptor and the iron chelator deferoxamine.

TH1 and TH2 helper T cell clones have been studied with respect to their sensitivity to inhibition of DNA synthesis by an IgG anti-transferrin receptor antibody (ATRA), the iron chelator deferoxamine, and the combination of the two reagents. TH1 clones are very sensitive to ATRA-mediated inhibition of DNA synthesis while TH2 clones are very resistant, but both TH1 and TH2 clones show significant down-modulation of surface transferrin receptors after ATRA exposure. TH2 clones exhibit larger chelatable iron storage pools than TH1 clones, however, and even partial chelation of TH2 cell storage iron does not fully convert a TH2 clone to the ATRA sensitivity pattern of a TH1 clone. It is therefore proposed that the greater resistance of TH2 clones to ATRA mediated inhibition derives from the combined effects of larger and less labile iron storage pools. These studies provide novel evidence indicating that nonuniform iron metabolism can exist within the T cell compartment and thus raise questions as to why such differences exist and how they can be integrated into models of the T cell activation process. These studies also suggest that the cell-mediated immune response in vivo, which is known to be sensitive to iron deficiency, may be evoked by effector cells which resemble TH1 clones insofar as iron metabolism is concerned.

Animals↗
PubMed1987

Preparation of 67Ga-labeled antibodies using deferoxamine as a bifunctional chelate. An improved method.

Radionuclides or anti-cancer drugs may be coupled to antibodies for specific transport to target tissues. We have previously reported that several proteins could be rapidly and efficiently labeled with gallium (67Ga) by using deferoxamine (DFO) as a bifunctional chelating agent. In the present paper, we have described the use of hetero-bifunctional agents for the conjugation of DFO with antibodies and investigated the effect of coupling agents on in vitro properties and biodistribution of 67Ga-labeled antibodies. 67Ga-labeled monoclonal antibodies retained antigen-binding activity when prepared under optimum conditions. The use of hetero-bifunctional reagents, such as succinimidyl 6-maleimido-hexanoate (EMCS) or N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP), which link thioether bonds and disulfide bridges prevented the formation of polymerized antibodies. Although high non-specific uptake in the liver was observed with radiolabels prepared by the homo-bifunctional agent glutaraldehyde, uptake in the liver was low with conjugates linked by hetero-bifunctional agents. 67Ga-labeled antibodies with thioether bonds showed in vivo stability, but the clearance from the circulation was the fastest with the radiolabel holding disulfide bonds. The coupling reagents used to link DFO and antibodies greatly influenced both in vitro properties and in vivo distribution of labeled antibodies and 67Ga-labeled antibodies provide a good model for the study of coupling methods and biodistribution of antibody conjugates.

Animals↗
PubMed1991

Iron chelation with a deferoxamine conjugate in hemorrhagic shock.

Oxygen-derived radicals are cytotoxic, highly reactive molecules that contribute to cellular death and injury in hemorrhagic shock. Iron released into the plasma in hemorrhagic shock may contribute to cellular damage by catalyzing lipid peroxidation of cell membranes. Deferoxamine (DFO) chelation of transitional metal ions prevents formation of these radicals and may diminish reperfusion injury. The conjugation of DFO to pentastarch (PS) decreases DFO toxicity and extends its half-life making it a potentially useful resuscitative fluid. A porcine hemorrhagic shock model was used to evaluate the effects of five resuscitative fluids on survival and hepatic function. Swine (11-16 kg) underwent splenectomy, liver biopsy, and placement of arterial and venous catheters. Awake animals were bled at 1 ml/kg/min to a MAP of 45 mm Hg, maintained for 1 hr, and resuscitated over 30 min with one of five fluids: Lactated Ringer's (LR); LR + free DFO 2.5 mg/ml (LR + DFO) (n = 6); 5% PS in LR (PS) (n = 6); 5% PS + free DFO (PS + DFO) 7.5 mg/ml (n = 6); 5% PS/DFO conjugate (7.5 mg/ml) in LR (n = 6). LR and LR + DFO received 3 ml/ml shed blood; PS, PS + DFO, and PS/DFO received 1 ml/ml shed blood. No shed blood was returned to the animals. There was no significant differences between groups in MAP, HR, CVP, and T pre- and post-resuscitation. No LR lived to sacrifice at 24 hr. Thirty-three percent of LR + DFO and PS + DFO animals died within minutes of receiving the free DFO containing resuscitative fluid, presumably from acute DFO toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Deferoxamine increases the susceptibility of beta-thalassemic, iron-overloaded mice to infection with Listeria monocytogenes.

The effect of the iron chelator deferoxamine (DFO) on resistance to infection with Listeria monocytogenes in mice with a condition analogous to human beta-thalassemia was studied. Intraperitoneal injection of 10 mg DFO resulted in significantly increased mortality when given one, three and six days before infection with L. monocytogenes (for all three time points, p less than 0.02). There were no significant differences in hematocrit, plasma iron, or splenic iron content between the two groups of mice during these time periods. In addition, splenic counts of L. monocytogenes were not significantly higher in DFO-treated compared to saline-treated mice three days after infection. Moreover, background C57Bl/6J mice were not more susceptible to Listeria infection after receiving DFO than were saline-treated controls. In conclusion, acute administration of DFO increases the susceptibility of beta-thalassemic mice to L. monocytogenes. The effect is not seen in background mice and suggests that DFO increases susceptibility to Listeria infection only in animals with iron overload.

Animals↗
PubMed1991

The severity of copper deficiency can be ameliorated by deferoxamine.

The present study was undertaken in order to determine whether hepatic iron overload plays a role in the exacerbation of copper deficiency. Weanling male Sprague-Dawley rats were fed a copper-deficient (0.6 microgram Cu/g) diet containing 62% fructose for 5 weeks. Some of the copper-deficient rats were injected daily with deferoxamine (DFX), an iron chelator that has been widely used to reduce iron overload. DFX reduced hepatic iron concentrations, which in turn ameliorated the pathology of copper deficiency when compared with nontreated copper-deficient animals. It is suggested that hepatic iron overload in a reduced environment plays a major role in the exacerbation of copper deficiency. Once the concentration of hepatic iron is reduced, the severity of the deficiency should be improved.

Animals↗
PubMed1991

Failure to alter the course of acute myelogenous leukemia in the rat with subcutaneous deferoxamine.

Deferoxamine (DFO) is an iron chelator that is known to inhibit acute non-lymphocytic leukemia cells in vitro. To explore the possibility that this drug has cytotoxic activity in vivo, rats were inoculated with a small lethal dose (10(2] of tumor cells from the transplantable BN acute myelogenous leukemia model. Animals were then treated with one of several regimens of bolus subcutaneous DFO: 10 mg/day x 5; 20 mg/day x 5; 10 mg/day x approximately 5 weeks; or no DFO. There were no consistently significant differences in survival between any of the DFO and untreated groups. Because the short plasma half-life of DFO was thought to be a potential reason for this lack of protection, a high molecular weight polymeric conjugate of DFO that is known to provide sustained intravascular drug levels was also studied. However, hydroxyethyl starch conjugated with DFO in amounts equivalent to 100 mg free drug (intraperitoneally for 5 days) also failed to have major impact on survival. These findings suggest that it may not be possible to achieve levels of this chelating agent in vivo that are cytotoxic for this disease.

Animals↗
PubMed1995

[Yersinia enterocolitica septicemia, iron overload and deferoxamine].

Infections due to Yersinia enterocolitica are usually limited to the bowel. When infection is generalized, the role of iron overload and iron chelation has been discussed. We report the case of a 55 year-old patient with sideroblastic anemia who received repetitive transfusions and deferoxamine for 4 years and heme arginate for 2 months, and who was admitted in our institution for Yersinia enterocolitica sepsis. Treatment by third-generation cephalosporins and aminoglycosides has allowed favorable outcome.

Anemia, Sideroblastic↗
PubMed1988

Neurotoxicity associated with deferoxamine therapy.

We have documented visual and auditory neurotoxicity in 42 of 89 patients with transfusion-dependent anemia who were receiving iron chelation therapy with subcutaneous deferoxamine (DFO). Of the affected groups, 13 presented with visual loss or deafness or both, and ophthalmologic, audiologic, and visual evoked potential studies (VEPs) uncovered abnormalities in 29 more. Four patients with visual loss had optic neuropathy with a marked decrease in acuity and loss of color vision. These 4, and 16 other asymptomatic patients, had abnormal VEPs. When DFO was stopped, 3 of 4 with visual problems regained normal visual function but VEPs remained abnormal. Of the other 16 with abnormal VEPs, 9 became normal or improved and 7 did not change; on restarting DFO, the 9 became abnormal again. There were 22 abnormal audiograms that showed a high-frequency sensorineural deficit; 13 patients were symptomatic and 4 needed hearing aids. On stopping DFO, 9 became asymptomatic but 15 audiograms remained abnormal and 2 deteriorated further on restarting the drug. An analysis of the clinical data showed that members of the affected group were younger, had lower serum ferritin values, and were self-administering higher doses of DFO/kg body weight. Significantly lower doses of DFO were being taken by patients without abnormalities than by those with visual symptoms, abnormal audiograms, or prolonged VEPs (P less than 0.001, less than 0.006, and less than 0.04, respectively). The data implicate high-dose DFO as a central factor in the pathogenesis of the neurotoxicity. Our serial studies provide the basis for effective yet safe DFO administration for patients who require the agent.

Adolescent↗
PubMed1990

Effects of combined superoxide dismutase and deferoxamine on recovery of brainstem auditory evoked potentials and EEG after asphyxial cardiac arrest in dogs.

In a randomized study in 23 dogs, we tested the following anti-free radical combination therapy, administered at the beginning of CPR, following apnea-induced cardiac arrest of 7 min: a) ventilation with 100% nitrogen for 30 s to allow the delivery of therapy before oxygen; b) superoxide dismutase (10 mg/kg i.a. followed by 10 mg/kg i.v. over 1 h) to scavenge the superoxide anion radical; and c) deferoxamine (20 mg/kg i.v. over 1 h) to prevent membrane lipid peroxidation. We evaluated the effects of this treatment on the recovery of cardiovascular and cerebral variables short term (6 h) after resuscitation. We reported previously that this treatment mitigated the post-arrest cerebral blood flow changes and enhanced the recovery of somatosensory evoked potentials. This is a secondary report from the same study concerning the effects of this treatment on the recovery of brainstem auditory evoked potentials (BAEPs) and EEG. Compared to control (n = 10), the experimental treatment (n = 10) did not exert a clearcut, significant effect on the recovery of BAEP which normalized in both groups at 1 h post-arrest and enhanced the post-arrest recovery of EEG spectra total power by reducing the post-arrest increase in slow frequency bands. However, the relative distribution of EEG frequencies never recovered the pre-arrest pattern in either group, during the 6 h post-arrest observation period. We conclude that the combination treatment tested enhances the recovery but does not normalize cerebral function post-arrest, suggesting that other treatments should also be entertained or that, indeed, such an insult may not be completely ameliorated by any such treatments.

Animals↗
PubMed1994

Influence of iron, deferoxamine and ascorbic acid on gentamicin-induced nephrotoxicity in rats.

1. Nephrotoxicity was induced in rats by injecting gentamicin intramuscularly (i.m.) at a dose of 80 mg/kg for 6 days. Treated animals demonstrated a typical pattern of nephrotoxicity characterized by increased serum creatinine and urea concentrations, and by necrosis of proximal tubular epithelium. 2. Pretreatment of rats with iron (Fe3+) at daily i.m. doses of 2, 4 and 8 mg/kg for 14 days, with gentamicin given during the last 6 days of treatment, significantly potentiated the gentamicin-induced increases in creatinine and urea concentrations and exacerbated renal histological damage. 3. Gentamicin significantly increased serum Fe3+ concentration in rats treated with Fe3+ and gentamicin, compared to Fe(3+)-treated rats. 4. The Fe3+ antidote deferoxamine (100 mg/kg, i.m.) given with gentamicin was ineffective in antagonizing the potentiating effect of Fe3+ on gentamicin-induced nephrotoxicity. 5. Ascorbic acid (50 mg/kg, i.m. for 14 days) was ineffective in altering the nephrotoxicity of gentamicin (80 mg/kg) given during the last 6 days of treatment. At a dose of 100 mg/kg for 14 days, ascorbic acid significantly reduced gentamicin-induced increases in creatinine and urea levels, and ameliorated proximal tubular damage. However, at a dose of 200 mg/kg, ascorbic acid exacerbated gentamicin-induced increases in creatinine and urea levels and increased the severity of the histological damage.

Animals↗
PubMed1995

Deferoxamine-induced cytotoxicity in human neuronal cell lines: protection by free radical scavengers.

Deferoxamine (DFO) caused decreased viability of human neuronal tumor cells (SK-N-MC neuroblastoma and U-373 MG astrocytoma) in a dose-dependent manner. The addition of stoichiometric amounts of ferric ions did not decrease the cytotoxic effect of DFO on the neuroblastoma cells. However, the cotreatments with various antioxidants, hydroxyl radical scavengers or intracellular Ca2+ release blockers significantly protected against the effects of DFO. These results suggest that DFO-induced cytoxicity may be not due to chelating iron, but due to the production of hydroxyl radicals and that intracellular Ca2+ may play a role in the cytotoxic effects of DFO.

Analysis of Variance↗
PubMed1990

An ESR study of the nitroxide radical of pentastarch-conjugated deferoxamine.

At higher concentrations, deferoxamine (DFO) reacts with hydroxyl radicals to produce a stable nitroxide free radical. Formation and decay of this nitroxide radical was investigated and compared with a novel modified pentastarch conjugate of DFO (MPS-DFO). Photolytic generation of hydroxyl radicals from H2O2 in the presence of free DFO produced a nitroxide radical with coupling constants of aN = 8.0 G and aH = 6.5 G. Under the same experimental conditions, equimolar concentrations of MPS-DFO produced an ESR signal of reduced intensity while iron-saturated MPS-DFO produced no signal. Incubation of free DFO with pentastarch (i.e., without conjugation) greatly decreased the intensity of the nitroxide radical signal. Using a spin-trapping technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), the pentastarch vehicle was shown to inhibit the DMPO-OH adduct formation. The decay of the DFO nitroxide radical decayed with a second-order rate constant while that of MPS-DFO decayed with a first-order rate constant. Thus, a novel derivative of DFO may provide some additional benefit in limiting DFO nitroxide radical formation and might explain the reported reduced in vivo toxicity of MPS-DFO relative to free DFO.

Deferoxamine↗
PubMed1991

Hyperoxic inhibition of newborn rat lung development: protection by deferoxamine.

Prolonged exposure to hyperoxia markedly inhibits normal lung development (alveolarization and respiratory surface area expansion) in immature animals. Since (a) hyperoxia results in excess hydroxyl radical (OH.) formation, (b) (OH.) is implicated in O2-induced lipid peroxidation and DNA alterations, and (c) both OH. formation and its interaction with DNA are Fe++ dependent; chelation of Fe++ should act to protect against pulmonary O2 toxicity and hyperoxic inhibition of lung development. We therefore treated litters of newborn rats with the iron chelator Deferoxamine mesylate (DES) (150 mg/kg/day) during a 10-day exposure to greater than 95% O2. Morphometric analysis demonstrated that compared to the mean airspace size in air control rat pups (Lm = 44.5 microns), hyperoxic exposure resulted in a 34% larger mean air space diameter in O2-saline rat lungs (59.5 microns) versus only an 11% enlargement in O2-DES lungs (51.1 microns*). Lung internal surface area (cm2) per 100-g body weight were air control = 4480, O2-saline = 3570 (decreases 20.3%), and O2-DES = 4125* (decreases 7.9%) (*p less than 0.05 versus O2-saline group). DES-treated animals also had significantly decreased lung conjugated diene levels during hyperoxic exposure and increased lung elastin content (reflective of preserved lung alveolar formation) compared to O2-saline rats. These results indicate that DES treatment substantially ameliorated the inhibitory effects of neonatal hyperoxic exposure on normal lung development.

Aging↗