The efficacy of deferiprone on tissues aluminum removal and copper, zinc, manganese level in rabbits

The Vital Role Played by Deferiprone in the Transition of Thalassaemia from a Fatal to a Chronic Disease and Challenges in Its Repurposing for Use in Non-Iron-Loaded Diseases

The iron chelating orphan drug deferiprone (L1), discovered over 40 years ago, has been used daily by patients across the world at high doses (75-100 mg/kg) for more than 30 years with no serious toxicity. The level of safety and the simple, inexpensive synthesis are some of the many unique properties of L1, which played a major role in the contribution of the drug in the transition of thalassaemia from a fatal to a chronic disease. Other unique and valuable clinical properties of L1 in relation to pharmacology and metabolism include: oral effectiveness, which improved compliance compared to the prototype therapy with subcutaneous deferoxamine; highly effective iron removal from all iron-loaded organs, particularly the heart, which is the major target organ of iron toxicity and the cause of mortality in thalassaemic patients; an ability to achieve negative iron balance, completely remove all excess iron, and maintain normal iron stores in thalassaemic patients; rapid absorption from the stomach and rapid clearance from the body, allowing a greater frequency of repeated administration and overall increased efficacy of iron excretion, which is dependent on the dose used and also the concentration achieved at the site of drug action; and its ability to cross the blood-brain barrier and treat malignant, neurological, and microbial diseases affecting the brain. Some differential pharmacological activity by L1 among patients has been generally shown in relation to the absorption, distribution, metabolism, elimination, and toxicity (ADMET) of the drug. Unique properties exhibited by L1 in comparison to other drugs include specific protein interactions and antioxidant effects, such as iron removal from transferrin and lactoferrin; inhibition of iron and copper catalytic production of free radicals, ferroptosis, and cuproptosis; and inhibition of iron-containing proteins associated with different pathological conditions. The unique properties of L1 have attracted the interest of many investigators for drug repurposing and use in many pathological conditions, including cancer, neurodegenerative conditions, microbial conditions, renal conditions, free radical pathology, metal intoxication in relation to Fe, Cu, Al, Zn, Ga, In, U, and Pu, and other diseases. Similarly, the properties of L1 increase the prospects of its wider use in optimizing therapeutic efforts in many other fields of medicine, including synergies with other drugs.

Taurine and deferiprone against Al-linked apoptosis in rat hippocampus

BACKGROUND

Aluminium (Al) overload has toxic effects on multiple organ systems, especially the nervous system. Al accumulation in the brain, especially the hippocampus, is an important factor contributing to Alzheimer's disease (AD). Deferiprone (DFP), a metal chelator, is used as a potential treatment for AD. In this study, we investigated the combined effect of taurine and DFP on Al chelation and hippocampal apoptosis in Al-exposed rats, as well as the underlying mechanisms of these effects to explore a possible therapy for AD.

METHODS

Male Wistar rats were divided into seven groups: negative control group (administered saline), Al-exposure group (administered AlCl₃ and saline), and five experimental groups (administered AlCl₃ and taurine, varying doses of DFP, or taurine with varying doses of DFP). After 8 weeks of treatment, the rats were sacrificed, and the terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end labelling (TUNEL) assay was used to detect hippocampal apoptotic cells. Real-time quantitative PCR was used to assess the expression of the Bcl2 and Bax genes, and a western blotting assay was used to evaluate BCL2, BAX, and cleaved caspase-3 levels.

RESULTS

Compared to the negative control group, the number of apoptotic cells in the hippocampus increased, Bcl2 expression significantly decreased, and BAX and cleaved caspase-3 levels increased in the Al-exposure group. The combination of taurine and DFP exerted a protective effect by inhibiting hippocampal cell apoptosis through the BCL2, BAX, and caspase-3 signalling pathways. Compared with the taurine-administered group, the group administered taurine with DFP showed a significantly increased Bcl2 and decreased Bax expression.

CONCLUSION

The combination of taurine and DFP is a potential candidate for the treatment of AD induced by Al exposure.

Influence of the Nonprotein Amino Acid Mimosine in Peptide Conformational Propensities from Novel Amber Force Field Parameters

Mimosine is a nonprotein amino acid derived from plants known for its ability to bind to divalent and trivalent metal cations such as Zn²⁺, Ni²⁺, Fe²⁺, or Al³⁺. This results in interesting antimicrobial and anticancer properties, which make mimosine a promising candidate for therapeutic applications. One possibility is to incorporate mimosine into synthetic short peptide drugs. However, how this amino acid affects the peptide structure is not well understood, reducing our ability to design effective therapeutic compounds. In this work, we used computer simulations to understand this question. We first built parameters for the mimosine residue to be used in combination with two classical force fields of the Amber family. Then, we used atomistic molecular dynamics simulations with the resulting parameter sets to evaluate the influence of mimosine in the structural propensities for this amino acid. We compared the results of these simulations with homologous peptides, where mimosine is replaced by either phenylalanine or tyrosine. We found that the strong dipole in mimosine induces a preference for conformations where the amino acid rings are stacked over more extended conformations. We validated our results using quantum mechanical calculations, which provide a robust foundation for the outcome of our classical simulations.

Cytoprotective effect of deferiprone against aluminum chloride-induced oxidative stress and apoptosis in lymphocytes

Aluminum (Al) is a toxic metal, and excessive Al accumulation causes immunosuppression. Deferiprone (DFP) is a well-known chelator and used in dialysis patients for removing Al from tissues. The present study aimed to investigate whether DFP treatment can attenuate immunotoxicity induced by aluminum chloride (AlCl3) in cultured lymphocytes. Lymphocytes were treated with 0 and 0.6 mmol/L AlCl3∙6H2O (pH 7.2) and/or 1.8 mmol/L DFP, respectively. Immune function of lymphocytes was assessed by T and B lymphocytes proliferation rates, T lymphocyte subpopulations and IL-2, IL-6 and TNF-α contents. In addition, lymphocyte damage was assessed by LDH activity, NO and MDA contents, NOS, SOD and GSH-Px activities, lymphocyte apoptosis index. These results showed that AlCl3 exposure reduced T and B lymphocyte proliferation rates, CD3+ and CD4+ T lymphocyte subpopulations, CD4+/CD8+ ratio, IL-2, IL-6 and TNF-α contents, SOD and GSH-Px activities, early and later lymphocyte apoptosis indexes while enhanced CD8+ T lymphocyte subpopulation, NO and MDA contents, LDH activity. DFP treatment attenuated the immunotoxicity of lymphocytes and reduced oxidative stress and lymphocyte apoptosis induced by AlCl3, indicating that DFP could protect lymphocytes against immunosuppression induced by AlCl3 through attenuating oxidative stress and apoptosis.

Influence of acid treatment on surface properties and in vivo performance of Ti6Al4V alloy for biomedical applications

The purpose of this work was to investigate the influence of acid treatment on the surface properties and in vivo performance of titanium grade 5 (Ti6Al4V) alloy. Mini-implants with surface treatment were inserted into New Zealand rabbit tibia for 1, 4 and 8 weeks. SEM analysis showed intercommunicated micropores in acid treated samples. AFM showed micron and sub-micron roughness. The thickness of the titanium oxide layer increased with surface treatment, with a significant reduction of Al and V concentration. Acid treated implant removal torque was larger than without treatment. The implants/bone interface of acid treated implants showed dense adhered Ca/P particles with spreading osteoblasts after 4 weeks and newly formed bone trabeculae after 8 weeks. Analysis of rabbit blood that received treated implant showed lower Al and V contents at all times. Acid treatment improved surface morphology and mechanical stability, which allowed initial events of osseointegration, while Al-V ion release was reduced. GRAPHICAL ABTSRACT.

Combination of DFP and Taurine Counteracts the Aluminum-Induced Alterations in Oxidative Stress and ATPase in Cortex and Blood of Rats

The study investigated the combined effect of 1,2-dimethyl-3-hydroxypyrid-4-one (DFP) and taurine on aluminum (Al) toxicity in cortex and blood of rats. The control group received 1 ml/kg/day saline solution for 8 weeks. Other animals were exposed to Al at a dose of 281.40 mg/kg/day orally for 4 weeks. Then, they were administered with 1 ml/kg/day saline solution, 400 mg/(kg·day) taurine, 13.82 mg/(kg·day) DFP, 27.44 mg/(kg·day) DFP, 400 mg/(kg·day) taurine +13.82 mg/(kg·day) DFP, and 400 mg/(kg·day) taurine +27.44 mg/(kg·day) DFP for 4 weeks. The changes in markers of oxidative stress, activities of antioxidant enzymes, and triphosphatase (ATPase) in the cortex and blood were determined. Administration of Al led to significant increase in the malondialdehyde (MDA) level and decrease in the activities of antioxidant enzymes, Na⁺K⁺-ATPase, Mg²⁺-ATPase, and Ca²⁺-ATPase in the cortex and blood, compared with the control group. DFP was observed to reverse alteration of these parameters except for Ca²⁺-ATPase activity. Treatment with taurine caused significant increase of GSH-Px activity and decrease of the MDA level in the cortex and serum and rise of Na⁺K⁺-ATPase in the blood. Effects of DFP combined with taurine were investigated and found to provide a more significant benefit than either drug alone. Combined intake of taurine and DFP could achieve an optimum effect of therapy for Al exposure.

Real-time Detection of Trace Copper in Brain and Kidney of Fish for Medical Diagnosis

For the detection of trace copper to be used in medical diagnosis, a sensitive handmade carbon nanotube paste electrode (PE) was developed using voltammetry. Analytical optimized conditions were found at 0.05 V anodic peak current. In the same conditions, various common electrodes were compared using stripping voltammetry, and the PE was found to be more sharply sensitive than other common electrodes. At optimum conditions, the working ranges of 3~19 μgL⁻¹ were obtained. The relative standard deviation of 70.0 μgL⁻¹ was determined to be 0.117% (n = 15), and the detection limit (S/N) was found to be 0.6 μgL⁻¹ (9.4 × 10⁻⁹ M). The results were applied in detecting copper traces in the kidney and the brain cells of fish.

The relationship of the lipoprotein SsaB, manganese and superoxide dismutase in Streptococcus sanguinis virulence for endocarditis

Streptococcus sanguinis colonizes teeth and is an important cause of infective endocarditis. Our prior work showed that the lipoprotein SsaB is critical for S. sanguinis virulence for endocarditis and belongs to the LraI family of conserved metal transporters. In this study, we demonstrated that an ssaB mutant accumulates less manganese and iron than its parent. A mutant lacking the manganese-dependent superoxide dismutase, SodA, was significantly less virulent than wild-type in a rabbit model of endocarditis, but significantly more virulent than the ssaB mutant. Neither the ssaB nor the sodA mutation affected sensitivity to phagocytic killing or efficiency of heart valve colonization. Animal virulence results for all strains could be reproduced by growing bacteria in serum under physiological levels of O(2). SodA activity was reduced, but not eliminated in the ssaB mutant in serum and in rabbits. Growth of the ssaB mutant in serum was restored upon addition of Mn(2+) or removal of O(2). Antioxidant supplementation experiments suggested that superoxide and hydroxyl radicals were together responsible for the ssaB mutant's growth defect. We conclude that manganese accumulation mediated by the SsaB transport system imparts virulence by enabling cell growth in oxygen through SodA-dependent and independent mechanisms.

The role of chelation in the treatment of other metal poisonings

These proceedings will review the role of chelation in five metals-aluminum, cadmium, chromium, cobalt, and uranium-in order to illustrate various chelation concepts. The process of "chelation" can often be oversimplified, leading to incorrect assumptions and risking patient harm. For chelation to be effective, two critical assumptions must be fulfilled: the presumed "metal toxicity" must correlate with a given body or a particular compartment burden, and reducing this compartmental or the body burden (through chelation) attenuates toxicity. Fulfilling these assumptions requires an established dose-response relationship, a validated, reproducible means of toxicity assessment (clinical, biochemical, or radiographical), and an appropriate assessment mechanisms of body or compartment burden. While a metal might "technically" be capable of chelation (and readily demonstrable in urine or feces), this is an insufficient endpoint. Clinical relevance must be affirmed. Deferoxamine is an accepted chelator for appropriately documented aluminum toxicity. There is a very minimal treatment window in order to address chelation in cadmium toxicity. In acute toxicity, while no definitive chelation benefit is described, succimer (DMSA), diethylenetriaminepentaacetate (DTPA), and potentially ethylenediaminetetraacetic acid (EDTA) have been considered. In chronic toxicity, chelation is unsupported. There is little evidence to suggest that currently available chromium chelators are efficacious. Similarly, scant human evidence exists with which to provide recommendation for cobalt chelation. DTPA has been recommended for cobalt radionuclide chelation, although DMSA, EDTA, and N-acetylcysteine have also been suggested. DTPA is unsupported for uranium chelation. Sodium bicarbonate is currently recommended, although animal evidence is conflicting.

Nanostructured severe plastic deformation processed titanium for orthodontic mini-implants

Titanium mini-implants have been successfully used as anchorage devices in Orthodontics. Commercially pure titanium (cpTi) was recently replaced by Ti-6Al-4V alloy as the mini-implant material base due to the higher strength properties of the alloy. However, the lower corrosion resistance and the lower biocompatibility have been lowering the success rate of Ti-6Al-4V mini-implants. Nanostructured titanium (nTi) is commercially pure titanium that was nanostructured by a specific technique of severe plastic deformation. It is bioinert, does not contain potentially toxic or allergic additives, and has higher specific strength properties than any other titanium applied in medical implants. The higher strength properties associated to the higher biocompatibility make nTi potentially useful for orthodontic mini-implant applications, theoretically overcoming cpTi and Ti-6Al-4V mini-implants. The purposes of the this work were to process nTi, to mechanically compare cpTi, Ti-6Al-4V, and nTi mini-implants by torque test, and to evaluate both the surface morphology and the fracture surface characteristics of them by SEM. Torque test results showed significant increase in the maximum torque resistance of nTi mini-implants when compared to cpTi mini-implants, and no statistical difference between Ti-6Al-4V and nTi mini-implants. SEM analysis demonstrated smooth surface morphology and transgranular fracture aspect for nTi mini-implants. Since nanostructured titanium mini-implants have mechanical properties comparable to titanium alloy mini-implants, and biocompatibility comparable to commercially pure titanium mini-implants, it is suggestive that nanostructured titanium can replace Ti-6Al-4V alloy as the material base for mini-implants.

Solid-phase extraction and separation procedure for trace aluminum in water samples and its determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS)

In the present study, a separation/preconcentration procedure for determination of aluminum in water samples has been developed by using a new atomic absorption spectrometer concept with a high-intensity xenon short-arc lamp as continuum radiation source, a high-resolution double-echelle monochromator, and a charge-coupled device array detector. Sample solution pH, sample volume, flow rate of sample solution, volume, and concentration of eluent for solid-phase extraction of Al chelates with 4-[(dicyanomethyl)diazenyl] benzoic acid on polymeric resin (Duolite XAD-761) have been investigated. The adsorbed aluminum on resin was eluted with 5 mL of 2 mol L(-1) HNO(3) and its concentration was determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Under the optimal conditions, limit of detection obtained with HR-CS FAAS and Line Source FAAS (LS-FAAS) were 0.49 μg L(-1) and 3.91 μg L(-1), respectively. The accuracy of the procedure was confirmed by analyzing certified materials (NIST SRM 1643e, Trace elements in water) and spiked real samples. The developed procedure was successfully applied to water samples.

Pharmacotherapy for Friedreich ataxia

Friedreich ataxia (FA) is a progressive genetic neurological disorder associated with degeneration of the dorsal columns, spinocerebellar tracts and other regions of the nervous system. The disorder results from mutations in the gene referred to as FXN. Almost all mutations are expansions of an intronic GAA repeat in this gene, which gives rise to decreased transcription of the gene product (called frataxin). Following these discoveries, drug discovery has moved at a rapid pace. Therapeutic trials in the next 5 years are expected to address amelioration of the effects of frataxin deficiency and methods for increasing frataxin expression. These therapies are directed at all levels of biochemical dysfunction in FA. Agents such as idebenone potentially improve mitochondrial function and decrease production of reactive oxygen species. Idebenone is presently in a phase III trial in the US and in Europe, with the primary outcome measure being neurological function. Deferiprone, an atypical iron chelator, may decrease build-up of toxic iron in the mitochondria in patients. It has entered a phase II trial in Europe, Australia and Canada directed toward improvement of neurological abilities. Finally, targeted histone deacetylase (HDAC) inhibitors and erythropoietin increase levels of frataxin when used in vitro, suggesting that they may provide methods for increasing frataxin levels in patients. Erythropoietin has been tested in a small phase II trial in Austria, while HDAC inhibitors are still at a preclinical stage. Symptomatic therapies are also in use for specific symptoms such as spasticity (baclofen). Thus, there is substantial optimism for development of new therapies for FA in the near future, and we suggest that one or several may be available over the next few years. However, continued development of new therapies will require creation of new, more sensitive measures for neurological dysfunction in FA, and clinically relevant measures of cardiac dysfunction.

Titanium alloy mini-implants for orthodontic anchorage: immediate loading and metal ion release

Removable osseointegrated titanium mini-implants were successfully used as anchorage devices in orthodontics. The early load is necessary to simplify the mini-implant methodology, but can lead to failure during osseointegration. The Ti-6Al-4V alloy was used instead of commercially pure Ti due to its superior strength. However, the corrosion resistance is low, allowing for metal ion release. The purpose of this work was to analyze the immediately loaded mini-implant fixation and to gauge the vanadium ion release during the healing process. Titanium alloy mini-implants were inserted in the tibiae of rabbits. After 1, 4 and 12 weeks, they were submitted to removal torque testing. There was no increase in the removal torque value between 1 and 4 weeks of healing, regardless of the load. Nevertheless, after 12 weeks, a significant improvement was observed in both groups, with the highest removal torque value for the unloaded group. The kidney, liver and lung were also extracted and analyzed by atomic absorption spectrometry. In comparison with the control values, the content of vanadium increased slightly after 1week, significantly increased after 4 weeks and decreased slightly after 12 weeks, without reaching the 1 week values. A stress analysis was carried out which enables both the prediction of the torque at which commercially pure (CP) Ti and Ti-6Al-4V deform plastically and the shear strength of the interface. This analysis reveals that the removal torques for CP Ti dangerously approach the yield stress. The results of this rabbit model study indicate that titanium alloy mini-implants can be loaded immediately with no compromise in their stability. The detected concentration of vanadium did not reach toxic levels in the animal model.