Acetabular Remodeling After a Varus Derotational Osteotomy in Children With Cerebral Palsy.

BACKGROUND: The optimal surgical intervention for hip dysplasia in cerebral palsy (CP) is controversial. The purpose of this study was to determine (1) whether an isolated varus derotation osteotomy (VDRO) for the treatment of CP hip dysplasia allows for acetabular remodeling as measured by acetabular depth ratio (ADR), (2) the predictive factors for acetabular remodeling after an isolated VDRO for the treatment of CP hip dysplasia, and (3) to establish the normal ADR in typical children for comparison. METHODS: Eighty-seven CP patients (174 hips) treated with an isolated VDRO between 2003 and 2009 were retrospectively reviewed. The average age at surgery was 4.6 years (range, 2.4 to 10.6 y) and the average follow-up period was 5.1 years (range, 1.1 to 9.9 y). Acetabular remodeling was assessed on radiographs by the ADR. Changes in preoperative and postoperative ADR were analyzed using linear mixed-effects models. Patients were divided into 2 different groups for the postoperative ADR analysis: Gross Motor Function Classification System (GMFCS) levels I, II, and III compared with GMFCS levels IV and V. The progression of ADR versus age was determined in a set of 917 normal children (1834 hips) for comparison. RESULTS: There was a statistically significant increase (improvement) in ADR postsurgically for the collective CP set (P<0.001) and for both GMFCS categories (I/II/III, IV/V: P<0.001). GMFCS level, sex, and intraoperative neck shaft angle (NSA) were determined to be significant predictors for postoperative ADR improvement. GMFCS level was the most significant predictor for an increase in ADR after surgery (P<0.001). Less improvement in ADR was observed in patients of GMFCS levels IV and V compared with patients of GMFCS levels I, II, and III (P<0.001). A lower intraoperative NSA resulted in greater postoperative increase in ADR (P<0.05). CONCLUSIONS: Overall, isolated VDRO allowed for acetabular remodeling in CP hip dysplasia. Acetabular remodeling was increased in patients of GMFCS levels I, II, and III compared with patients of GMFCS levels IV and V. Increased varization at the time of VDRO improved acetabular remodeling. This study recommends considering GMFCS level and intraoperative NSA during surgical planning for CP hip dysplasia.

CT outperforms radiographs at a comparable radiation dose in the assessment for spondylolysis.

BACKGROUND: Lumbar spondylolysis, a unilateral or bilateral fracture at pars interarticularis, is a common cause of low back pain in children. The initial imaging study in the diagnosis of lumbar spondylolysis has historically been lumbar spine radiographs; however, radiographs can be equivocal or false-negative. Definitive diagnosis can be achieved with computed tomography (CT), but its use has been limited due to the dose of ionizing radiation to the patient. OBJECTIVE: By limiting the z-axis coverage to the relevant anatomy and optimizing the CT protocol, we are able to provide a definitive diagnosis of fractures of the pars interarticularis at comparable or lower radiation dose than commonly performed lumbar spine radiographs. As there is no gold standard for the diagnosis of spondylolysis besides surgery, we compared interobserver agreement and degree of confidence to determine which modality is preferable. MATERIALS AND METHODS: Sixty-two patients with low back pain ages 5-18 years were assessed for the presence of spondylolyis. Forty-seven patients were evaluated by radiography and 15 patients were evaluated by limited field-of-view CT. Both radiographic and CT examinations were assessed anonymously in random order for the presence or absence of spondylolyisis by six raters. Agreement was assessed among raters using a Fleiss Kappa statistic for multiple raters. RESULTS: CT provided a significantly higher level of agreement among raters than radiographs (P < 0.001). The overall Kappa for rater agreement with radiographs was 0.24, 0.34 and 0.40 for 2, 3 or 4 views, respectively, and 0.88 with CT. CONCLUSION: Interobserver agreement is significantly greater using limited z-axis coverage CT when compared with radiographs. Radiologist confidence improved significantly with CT compared to radiographs regardless of the number of views.

Methods for the creation of cyclic Peptide libraries for use in lead discovery.

The identification of initial hits is a crucial stage in the drug discovery process. Although many projects adopt high-throughput screening of small-molecule libraries at this stage, there is significant potential for screening libraries of macromolecules created using chemical biology approaches. Not only can the production of the library be directly interfaced with a cell-based assay, but these libraries also require significantly fewer resources to generate and maintain. In this context, cyclic peptides are increasingly viewed as ideal scaffolds and have proven capability against challenging targets such as protein-protein interactions. Here we discuss a range of methods used for the creation of cyclic peptide libraries and detail examples of their successful implementation.

Ruthenium(II) thiacrown complexes incorporating noninnocent redox active ligands: synthesis, electrochemical properties, and theoretical studies.

The synthesis and characterization of a series of nine new complexes incorporating [Ru(II)Cl([n]aneS(3))] (n = 12,14, 16) metal centers coordinated to redox active catechol ligands is reported. The solid-state structure of one of these complexes has been determined by X-ray crystallography. The redox properties of these complexes have been probed experimentally through absorption spectroscopy, cyclic voltammetry, and spectroelectrochemistry, as well as computationally through density functional theory calculations. These studies reveal that, whereas the tetrachlorocatechol-based complexes are isolated with the dioxolene unit in the catechol form, the rest of the complexes are isolated in the semiquinone oxidation state. It was also found that the Ru(III/II)-based couple for the complexes is dependent on the nature of the thiacrown ligand coordinated to the metal center. A combination of optical and theoretical studies revealed that the absorption spectra of the complexes contain contributions from a variety of charge transfer processes; in the case of the tetrachlorocatechol complexes these transitions include catechol-to-thiacrown ligand-to-ligand charge transfer.

Kinetically locked, trinuclear Ru(II) metallo-macrocycles--synthesis, electrochemical, and optical properties.

Using a [Ru(II)([9]aneS3)] templating moiety, kinetically-locked, metallomacrocycles incorporating adenine based ligands have been synthesised through self-assembly. The kinetically robust nature of these structures is confirmed by electrochemical studies: each can be reversibly oxidised in a four-member redox series, containing two formally mixed valence states. Unusually, the electrochemically derived comproportionation constants for these mixed valence states are very different, suggesting that intermetallic coupling differs between the two states. Spectroelectochemistry studies confirm that while the [Ru(II)2Ru(III)] state is valence localised, the [Ru(II)Ru(III)2] state is electronically delocalised. Mechanisms by which this switching effect could occur, which involve the unusual connectivities in these mixed valence species, are presented.

Structure and properties of Dinuclear [RuII([n]aneS4)] complexes of 3,6-Bis(2-pyridyl)-1,2,4,5-tetrazine.

The synthesis of dinuclear [Ru(II)([n]aneS(4))] (where n = 12, 14) complexes of the bridging ligand 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine are reported. The X-ray structures of both of the new complexes are compared to a newly obtained structure for a dinuclear [Ru(II)([9]aneS(3))]-based analogue, whose synthesis has previously been reported. A comparison of the electrochemistry of the three complexes reveals that the first oxidation of the [Ru(II)([n]aneS(4))]-based systems is a ligand-based couple, indicating that the formation of the radical anion form of the bridging ligand is stabilized by metal center coordination. Spectroelectrochemistry studies on the mixed-valence form of the new complexes suggest that they are Robin and Day Class II systems. The electrochemical and electronic properties of these complexes is rationalized by a consideration of the pi-bonding properties of thiacrown ligands.