High-speed Computers as a Supplement to Graphical Methods. III. Twist Matrix Methods for Minimizing the Error-square Sum in Problems with Many Unknown Constants.

Sillén, Lars Gunnar; Hartiala, K.; Liem, Djiet Hay; Ryhage, R.; Stevens, Roger

doi:10.3891/acta.chem.scand.18-1085

Cited by 141 publications

(11 citation statements)

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“…values. Optimization was performed by using pitmapping29 or simplex30 as nonlinear least‐squares algorithms. Mass balance equations were solved, that is, species concentrations at equilibrium were obtained, by means of the Newton–Raphson method 30.…”

Section: Methodsmentioning

confidence: 99%

Possible Chelating Agents for Iron and Aluminium – 4‐Hydroxy‐5‐methyl‐ and 4‐Hydroxy‐1,5‐dimethyl‐3‐pyridinecarboxylic Acid

Dean¹,

Sija²,

Zsigó³

et al. 2013

Eur J Inorg Chem

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4-Hydroxy-5-methyl-3-pyridinecarboxylic acid (DQ5) and 4-hydroxy-1,5-dimethyl-3-pyridinecarboxylic acid (DQ715) were synthesized and evaluated for possible application in iron and aluminium chelation therapy. Metal ion/ligand solution chemistry, electrochemistry, cytotoxicity and chelation efficiency in vitro were studied. The solution chemistry of each ligand with Fe-III or Al-III was investigated in aqueous NaCl solution (0.6 m) at 25 degrees C by means of potentiometric titrations, UV/Vis spectrophotometry, ESI-MS and (in the case of Al-III) by H-1 NMR measurements. Accordingly, the effects of the 5-methyl substitution of 4-hydroxy-3-pyridinecarboxylic acid on the stability of Fe and Al complexes were rationalized. Electrochemical measurements allowed to obtain the standard reduction potentials of some Fe-III/DQ715 complexes and their kinetic constants. These results indicate that Fe-III/DQ715 complexes do not redox cycle in vivo and complex formation is not kinetically limited. The lack of cytotoxicity of DQ715 was demonstrated on human embryonic kidney cells (HEK-293): the IC50 values calculated from the dose-survival curves were 1.4 (after 24 h treatment) and 0.8 mmol/L (after 48 h treatment). The treatment of cells with DQ715 in the presence of Fe-III sensibly reduced antiproliferative activity promoted by the metal ion, which suggests an Fe-III chelate effect induced by DQ715. According to our results, DQ715 is a chelator for both metal ions, whereas DQ5 is more suitable as a selective Al chelator

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Section: Methodsmentioning

confidence: 99%

Possible Chelating Agents for Iron and Aluminium – 4‐Hydroxy‐5‐methyl‐ and 4‐Hydroxy‐1,5‐dimethyl‐3‐pyridinecarboxylic Acid

Dean¹,

Sija²,

Zsigó³

et al. 2013

Eur J Inorg Chem

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“…PITMAP minimizes the sum of the squares of the differences between experimental and calculated absorbance values. Optimization has been performed using pitmapping (Sillén, ) or simplex (Press et al ., ) as nonlinear least squares algorithms. Stability constants for Ga(III)/hydroxo complexes have been taken from literature and were kept constant during the elaboration of the UV–vis spectra: log β GaOH =−3.31, log β Ga(OH)2 =−6.76, log β Ga(OH)3 = −11.16, log β Ga(OH)4 = −17.17 (Jackson & Byrne, ).…”

Section: Methodsmentioning

confidence: 99%

Reduction in absorption of gallium maltolate in adult horses following oral administration with food: chemistry and pharmacokinetics

Pollina¹,

Pepe

Dean

et al. 2013

Vet Pharm & Therapeutics

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Gallium (Ga) is under study for the treatment of osteolytic disorders in equines. Previous studies indicate that oral gallium maltolate (GaM) would provide a higher bioavailability than oral Ga salts. However, oral administration to adult horses of 2 mg/kg of GaM, in the form of a solution mixed with food, did not lead to detectable Ga levels in plasma. Therefore, a study was performed to model the chemical behaviour of GaM in the digestive tract. The equilibrium formation constants for Ga(III) and maltol were calculated by means of UV–visible measurements and validated by 1H-NMR measurements at selected pH values. Data indicate that the dissociation of GaM in aqueous solutions is very rapid, while the re-association is slower. Based on these results, poor Ga absorption seems to be due to the equilibrium dissociation of GaM in the stomach and to its slow formation rate in the intestine. The concomitant presence of high concentrations of phytates (strong charged metal chelating agents, which represent about 1% of dry matter in vegetables) might also explain the low absorption of GaM by the gastrointestinal tract. Methods of optimizing Ga absorption after oral administration of GaM require further investigation.

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“…The spectrophotometric data using absorbance values from 20 wavelengths (between 400 and 800 nm) were processed with both the Specfit19−22 and Letagrop‐Spefo17,18 programs in order to calculate the thermodynamic constants of the absorbing species and their corresponding electronic spectra. The range of values for the residual‐squares sum [Σ(A exp − A calcd. )…”

Section: Methodsmentioning

confidence: 99%

Iron(III) Chelation: Tuning of the pH Dependence by Mixed Ligands

et al. 2003

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The iron(III) chelating properties of two heteropodands with 8-hydroxyquinoline and catechol binding groups were examined and compared to those of the corresponding homopodal analogues, O-TRENSOX and TRENCAMS. Like the parent homopodands, the two heteropodands are based on the TREN scaffold and the chelating units are connected by amide groups, TRENSOX2CAMS having two 8-hydroxyquinoline and one catechol arms and TRENSOXCAMS2 one 8-hydroxyquinoline and two catechol moieties. The aqueous coordination chemistry of these ligands was examined by po-

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High-speed Computers as a Supplement to Graphical Methods. III. Twist Matrix Methods for Minimizing the Error-square Sum in Problems with Many Unknown Constants.

Cited by 141 publications

References 0 publications

Possible Chelating Agents for Iron and Aluminium – 4‐Hydroxy‐5‐methyl‐ and 4‐Hydroxy‐1,5‐dimethyl‐3‐pyridinecarboxylic Acid

Possible Chelating Agents for Iron and Aluminium – 4‐Hydroxy‐5‐methyl‐ and 4‐Hydroxy‐1,5‐dimethyl‐3‐pyridinecarboxylic Acid

Reduction in absorption of gallium maltolate in adult horses following oral administration with food: chemistry and pharmacokinetics

Iron(III) Chelation: Tuning of the pH Dependence by Mixed Ligands

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