Functional assessment in patients with osteoporotic wrist fractures treated with external fixation: a review of randomized trials.

INTRODUCTION: Osteoporosis is a chronic and progressive condition that leads to decreased bone mass and skeletal fragility which may result in fractures, disability, pain, deformity and even death. Fractures of the wrist are the most common symptomatic fracture related to osteoporosis in which up to 80% of the persons with this fracture type have low bone mass. External fixation is minimally-invasive and is used in particular for the treatment of displaced, unstable fractures. OBJECTIVE: The present systematic review will present functional outcome assessment in randomized controlled trials in the aged with distal radius fractures and treated with external fixation. MATERIALS AND METHODS: Multiple databases including Medline, EMBASE, CINAHL, AMED and OVID Healthstar were searched. MESH headings such as: "Radius fractures" or "wrist injuries" were used in combination with "randomized controlled trials". Studies were included if the surgical treatment was external fixation, mean patient age was 50 years and over, and were in the English language. RESULTS: The primary focus of wrist outcome assessments in patients treated with external fixation were based on traditional measures such as wrist range of movement and grip strength reflecting the need to shift the focus in future protocols towards measuring a patient's functional ability, measuring the difficulty of task performance and compensatory mechanisms. Furthermore, it is essential to take into account more evidence of instrument development before clinicians can reliably choose the best measure to assess the aged treated with external fixation.

The effect of histidyl residues on the complexation of bis(imidazolyl) containing tripeptides with copper(II) ion.

Copper(II) complexes of tripeptide derivatives of bis(imidazol-2-yl) group have been studied by potentiometric, UV-visible and EPR spectroscopic methods. The peptide molecules correspond to the amino acid sequence of collagen containing histidyl residues in different locations and were connected to the bis(imidazol-2-yl) group either on the C-termini (BOC-Pro-Leu-His-BIMA, BOC-His-Leu-Gly-BIMA) or on the N-termini (BIP-His-Ala-Gly-OEt, BIP-Ile-Ala-His-OMe). It was concluded that the imidazole nitrogen donor atoms of the bis(imidazol-2-yl) moiety are the primary metal binding sites, but the histidyl imidazole nitrogens in the side chains have also some effect on the stability and the coordination mode of the complexes. All ligands can coordinate tridentately to copper(II) ion forming a six-membered chelate and a macrochelate in the [CuL]2+ complexes, which results in a slight distortion in the coordination geometry of [CuL2]2+ complexes. The deprotonation and coordination of amide nitrogens, however, were not observed in any cases.

Can the 1,5-disubstituted tetrazole ring modify the co-ordinating ability and biological activity of opiate-like peptides?

The copper(II) complexing ability and the biological activity of beta-casomorphin-7 tetrazole analogues have been investigated. Potentiometric and spectroscopic (UV-Vis, CD and EPR) studies have been used to establish the thermodynamic stability, speciation and structure of Cu(II) complexes with YP-psi(CN4)-FPGPI-NH2 (1), YPF-psi(CN4)-AGPI-NH2 (2) and YPFP-psi(CN4)-GPI-NH2 (3). Comparison of the binding ability of the tetrazole analogues reveals that the most effective ligand for copper(II) is YPF-psi(CN4)-AGPI-NH2. The effectiveness of this ligand comes from its particular conformation suited for the Cu(II) 2N co-ordination mode in the physiological pH region. The ability of casomorphin tetrazole analogues to activate rat mast cells to histamine release in vitro in the presence of copper(II) has been studied.

Ternary complex formation between VO(IV)-picolinic acid or VO(IV)-6-methylpicolinic acid and small blood serum bioligands.

In order to assess the role of the low molecular mass bioligands of blood serum in vanadium binding, a study was made of the interactions of the complexes formed in the VO(IV)-picolinic acid and VO(IV)-6-methylpicolinic acid systems with various low molecular mass constituents of blood serum, such as oxalate, lactate, citrate and phosphate. The speciation of VO(IV) in these ternary systems and also in the binary VO(IV)-picolinic acid and VO(IV)-6-methylpicolinic acid systems was studied by pH-potentiometry at 25 degrees C and at an ionic strength I = 0.2 M (KCl). The binding modes of the complexes formed were determined by spectral (electronic absorption and EPR) methods. Picolinic acid and 6-methylpicolinic acid were found to form mono and bis complexes through the pyridine nitrogen and carboxylate oxygen, but the presence of the methyl group in 6-methylpicolinic acid surprisingly decreases the stability of its complexes significantly. The results obtained on the ternary systems reveal that mixed ligand complex formation is favoured in these systems, especially with citrate, and must therefore be taken into account in the speciation description of VO(IV) in blood serum.

Effect of the tetrazole cis-amide bond surrogate on the complexing ability of some enkephalin analogues toward Cu(II) ions.

A study of the effect of the tetrazole moiety, a cis-amide bond surrogate, on the Cu(II) coordinating properties of oligopeptides is reported. The insertion of the tetrazole moiety psi (CN4) into the peptide sequence of [Leu5]enkephalin considerably changes the coordination ability of the ligand. Potentiometric and spectroscopic results indicate that if the tetrazole moiety is in a suitable position in the peptide chain, i.e. if it follows the third residue, an unusual stable CuH-1L species involving 4N coordination is formed in the physiological pH region. The tetrazole psi (CN4) ring provides one of these nitrogens. The data indicate that Cu(II) ions are strongly trapped inside a bent peptide backbone. However, the coordination mode involving the tetrazole ring nitrogen does not prevent the hydrolysis process under strongly basic conditions.

Specific interactions of bovine and human beta-casomorphin-7 with Cu(II) ions.

Complex formation between Cu(II) and human and bovine beta-casomorphin heptapeptides, Tyr-Pro-Phe-Val-Glu-Pro-Ile and Tyr-Pro-Phe-Pro-Gly-Pro-Ile, respectively, was investigated by pH potentiometry and spectroscopic (CD, EPR and electronic absorption) techniques. The results showed the critical impact of Pro residues on the complex equilibria formed. The presence of the Pro residue at the second position leads to formation of very stable dimeric species in which two metal ions co-ordinate to N-terminal ¿NH2, C=O¿ binding sites of one peptide molecule and the deprotonated phenolic oxygen of the second ligand molecule. The presence of two additional hydrophobic residues on the C-terminal makes heptapeptide molecule much more effective ligand than its pentapeptide N-terminal fragment.

Copper(II) Complexes of Opiate-like Food Peptides.

The alpha-casein peptide fragment (90-96) Arg-Tyr-Leu-Gly-Tyr-Leu-Glu, one of the exorphins called "food hormones", is an efficient ligand for Cu(II) ions. Potentiometric and spectroscopic studies on aqueous solutions indicate that, depending on the pH range, complex species with different coordination modes (involving the amino and the deprotonated amide groups) are formed. The phenolate side chain of the Tyr residue is not involved in the metal coordination.

Co-ordination ability of Cu(2+) ion toward the nucleobase-amino acid willardiine.

The complex formation between Cu(II) and dl-willardiine [1-(2-amino-2-carboxyethyl)uracil], an analog of phenylalanine containing the uracil residue, was investigated by potentiometric and spectral studies. The results indicate that the primary metal binding site of the ligand is the alpha-amino-carboxylate chelating set. The uracil moiety, however, can coordinate the metal ion in basic solution giving rise to intermolecular bridging.

Binding ability of Cu2+ ions by opiate-like fragments of bovine casein.

The coordination modes of Cu(II) to alpha-casein (90-95) and alpha-casein (90-96) peptides with opioid activity isolated from pepsin hydrolisates of alpha-casein were investigated by means of electron paramagnetic resonance, absorption, and circular dichroism spectroscopy and potentiometry. The results allow the identification of the complex species involved and the attribution of the spectral data set to the various complex structures. According to the spectroscopic data, a phenolate side-chain of Tyr residue belonging to the Gly-Tyr-Leu or Gly-Tyr-Leu-Gln fragment of the peptides is involved in the metal coordination in a complex which is a minor species at neutral pH range.

Potentiometric and spectroscopic studies on the copper(II) complexes of peptide hormones containing disulfide bridges.

Copper(II) complexes of oxytocin, 4-Glu-oxytocin, 5-Asp-oxytocin, and GlyGlyGly-Lys8-vasopressin were studied by potentiometric, EPR, and UV-visible spectroscopic methods. The formation of 4N-coordinated complexes was characteristic of all ligands. This type of coordination is especially favored for oxytocin due to the specific conformation of the ring coupled by the disulfide bridge. The coordination of the gamma-carboxylate group of 4-Glu-oxytocin and a disulfide sulfur atom of GlyGlyGly-Lys8-vasopressin was reported to occur in the 2N-complexes over medium pH range.

Coordination ability of digalactosamine, and di- and trigalacturonic acids. Potentiometric and spectroscopic studies of Cu(II) complexes.

Potentiometric and spectroscopic (EPR, CD, and absorption spectra) data obtained for digalactosamine and di- and trigalacturonic acid with Cu(II) have shown that the di-sugar binding is usually less efficient than that of monomeric units while the tri-sugar can probably simultaneously use two terminal subunits to coordinate a metal ion. The latter result may have some relevance for metal binding by polysaccharides. All sugar ligands use amino or carboxylate functions as an anchor site, as in monomeric units. Bulky oligomeric ligands protect formation of the bis complexes. This causes the hydrolysis to be a dominant process at higher pH.

EPR investigation of the oxovanadium(IV) complexes formed by the tripeptide glutathione and some related ligands in aqueous solution.

Complex formation between oxovanadium(IV) and glutathione (gamma-L-glutamyl-L-cysteinylglycine, GSH) was investigated in aqueous solution by EPR and electron absorption spectroscopy to identify the complexed species that were reported to form upon reduction of exogenous vanadium(V) in cellular systems. The complexing behavior of the related ligands glycine, N-acetyl-glycine, 3-mercaptopropionic acid, cysteamine, L-cysteine, N-acetyl-L-cysteine, N-acetyl-cysteamine, and oxidized glutathione (GSSG) was also examined in order to have suitable reference models. The results are compared with those reported previously.

Oxovanadium(IV) complex formation by simple sugars in aqueous solution.

The binding of oxovanadium(IV) to simple sugars in neutral or basic aqueous solution, as studied by EPR and electronic absorption spectroscopy, is reported. The complexation is favored in basic media and involves the coordination of the metal ion to couples of adjacent deprotonated hydroxyls of the sugar molecule. However, only the ligands provided with cis couples can adopt this chelating ligand behavior. The ability of the cis hydroxyl couples to yield chelated complexes has been related to the structural rearrangement (decrease of the O-C-C-O torsion angle in the five-membered chelated ring) needed to permit the oxovanadium(IV) coordination by the sugar molecule.

Influence of dihydralazine on the generation of hydroxyl radicals by human granulocytes.

Hydroxyl radical generation by living human granulocytes was determined by ESR using DMPO as a spin trapping reagent. The influence of dihydralazine and exogenous superoxide dismutase (SOD) on the radical generation was observed. In the presence of dihydralazine the radical production increases distinctly; the higher hydroxyl radical production is observed for the dihydralazine-SOD containing system which is explained by the partial decomposition of the enzyme in the presence of dihydralazine. No effect of dihydralazine on the lipid fluidity of the granulocyte membrane and phase transition in the membrane of living granulocytes was observed.

In vitro interaction of mutagenic chromium (VI) with red blood cells.

The interaction of mutagenic Cr(VI) with red blood cells has been studied by ESR spectroscopy. Signals of two Cr(V) species are observed almost immediately after contacting red cells with chromate(VI) aqueous solution at pH 7.4. The signal at go = 1.985, which decays within one hour, is attributed to a Cr(V) complex formed by glutathione due its reducing and chelating ability. The other signal at go = 1.979, which is distinctly more persistent, may indicate that some immobilization of the formed Cr(V) ions takes place on the macromolecular cell components, e.g. glycoproteins.

D-galactosamine complexes with copper(II), nickel(II), and cobalt(II).

The potentiometric and spectroscopic methods were applied to describe the equilibria for the Cu(II), Ni(II), and Co(II), D-galactosamine solutions. The stability constants, the spectral data, and the results obtained earlier precisely defined the binding ability of the aminosugars.