Synthesis, characterization and DNA binding studies of two mixed ligand complexes of ruthenium(II)

Two mixed ligand complexes [Ru(bpy)(2)(DMHBT)]Cl(2)(1) and [Ru(phen)(2)(DMHBT)]Cl(2) (2) (where DMHBT is 11,13-dimethyl-13H-4,5,9,11,14-hexaaza-benzo[b]triphenylene-10,12-dione) have been synthesized and characterized by electrospray ionization (ESI) mass, (1)H-(1)H correlation spectroscopy (COSY), electronic spectroscopy, fluorescence spectroscopy and cyclic voltammetry. Spectroscopic titration and viscosity changes of calf thymus (CT)-DNA in the presence of incremental amount of complexes 1 and 2 clearly demonstrate that both these complexes bind intercalatively to DNA, with binding constant 2.87+/-0.20 x 10(4)M(-1) and 1.01+/-0.20 x 10(5)M(-1) for complexes 1 and 2, respectively. All the experimental evidences suggest that the ancillary ligand 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) influences the intercalative binding of these complexes to DNA.     

Radiosynthesis and biodistribution of cyclic RGD peptides conjugated with novel [18F]fluorinated aldehyde-containing prosthetic groups

Achieving high-yielding, robust, and reproducible chemistry is a prerequisite for the (18)F-labeling of peptides for quantitative receptor imaging using positron emission tomography (PET). In this study, we extend the toolbox of oxime chemistry to include the novel prosthetic groups [(18)F]-(2-{2-[2-(2-fluoroethoxy)ethoxy]ethoxy}ethoxy)acetaldehyde, [(18)F]5, and [(18)F]-4-(3-fluoropropoxy)benzaldehyde, [(18)F]9, in addition to the widely used 4-[(18)F]fluorobenzaldehyde, [(18)F]12. The three (18)F-aldehydes were conjugated to the same aminooxy-bearing RGD peptide and the effect of the prosthetic group on biodistribution and tumor uptake studied in mice. The peptide conjugate [(18)F]7 was found to possess superior in vivo pharmacokinetics with higher tumor to blood, tumor to liver, tumor to muscle, and tumor to lung ratios than either [(18)F]10 or [(18)F]13. The radioactivity from the [(18)F]7 conjugate excreted more extensively through the kidney route with 79%id passing through the urine and bladder at the 2 h time point compared to around 55%id for the more hydrophobic conjugates [(18)F]10 and [(18)F]13. The chemical nature of a prosthetic group can be employed to tailor the overall biodistribution profile of the radiotracer. In this example, the hydrophilic nature of the ethylene glycol containing prosthetic group [(18)F]5 clearly influences the overall excretion pattern for the RGD peptide conjugate.     

Effect of the Low Risk Ankle Rule on the frequency of radiography in children with ankle injuries

Background:

The Low Risk Ankle Rule is a validated clinical decision rule that has the potential to safely reduce radiography in children with acute ankle injuries. We performed a phased implementation of the Low Risk Ankle Rule and evaluated its effectiveness in reducing the frequency of radiography in children with ankle injuries.

Methods:

Six Canadian emergency departments participated in the study from Jan. 1, 2009, to Aug. 31, 2011. At the 3 intervention sites, there were 3 consecutive 26-week phases. In phase 1, no interventions were implemented. In phase 2, we activated strategies to implement the ankle rule, including physician education, reminders and a computerized decision support system. In phase 3, we included only the decision support system. No interventions were introduced at the 3 pair-matched control sites. We examined the management of ankle injuries among children aged 3–16 years. The primary outcome was the proportion of children undergoing radiography.

Results:

We enrolled 2151 children with ankle injuries, 1055 at intervention and 1096 at control hospitals. During phase 1, the baseline frequency of pediatric ankle radiography at intervention and control sites was 96.5% and 90.2%, respectively. During phase 2, the frequency of ankle radiography decreased significantly at intervention sites relative to control sites (between-group difference −21.9% [95% confidence interval [CI] −28.6% to −15.2%]), without significant differences in patient or physician satisfaction. All effects were sustained in phase 3. The sensitivity of the Low Risk Ankle Rule during implementation was 100% (95% CI 85.4% to 100%), and the specificity was 53.1% (95% CI 48.1% to 58.1%).

Interpretation:

Implementation of the Low Risk Ankle Rule in several different emergency department settings reduced the rate of pediatric ankle radiography significantly and safely, without an accompanying change in physician or patient satisfaction. Trial registration: ClinicalTrials.gov, no. {"type":"clinical-trial","attrs":{"text":"NCT00785876","term_id":"NCT00785876"}}NCT00785876.Pediatric ankle injuries result in more than 2 million emergency department visits in Canada and the United States each year (Jeanette Tyas, Canadian Institute of Health Information: unpublished data, 2007).^1,2 Radiographs are ordered for 85%–95% of these children,³ although only 12% of these reveal a fracture.⁴ Thus, radiography is unnecessary for most children’s ankle injuries, and these high rates of radiography needlessly expose children to radiation and are a questionable use of resources.The Low Risk Ankle Rule has 100% sensitivity with respect to identifying clinically important pediatric ankle fractures and has the potential to safely reduce imaging by about 60%.⁴ When the application of the rule suggests that radiography is not needed, it has been shown that any fractures that might be missed are clinically insignificant and can be safely and cost-effectively managed like an ankle sprain, with superior functional recovery.⁵ Finally, the Low Risk Ankle Rule has been shown to have excellent acceptability when tested on emergency physicians.⁶The main objective of this study was to implement the ankle rule in several different emergency department settings using a multimodal knowledge translation strategy and to evaluate its impact on the frequency of radiography in children presenting with acute ankle injuries.     

Cortical Hand Bone Porosity and Its Association with Distal Radius Fracture in Middle Aged and Elderly Women

Objective

Reduced bone mineral density (BMD), assessed by Dual Energy X-ray absorptiometry (DXA), is a well-known risk factor for fragility fracture. A large proportion of patients with fracture have only slightly reduced BMD. Assessment of other bone structure features than BMD may improve identification of individuals at increased fracture risk. Digital X-ray radiogrammetry (DXR), which is a feasible tool for measurement of metacarpal cortical bone density, also gives an estimate of cortical bone porosity. Our primary aim was to explore the association between cortical porosity in the hand assessed by DXR and distal radius fracture.

Methods

This case-control study included 123 women >50 years with distal radius fracture, and 170 controls. DXR was used to measure metacarpal BMD (DXR-BMD), cortical porosity (DXR-porosity), thickness (DXR-CT) and bone width (DXR-W) of the hand. Femoral neck BMD was measured by DXA.

Results

The fracture group had a statistically significant lower DXR-BMD (0.492 vs. 0.524 g/cm² p<0.001), higher cortical DXR-porosity (0.01256 vs. 0.01093, p<0.001), less DXR-CT (0.148 vs. 0.161cm, p<0.001) and lower femoral neck DXA-BMD (0.789 vs. 0.844 g/cm², p = 0.001) than the controls. In logistic regression analysis adjusted for age, a significant association with distal radius fracture (OR, 95% CI) was found for body mass index (0.930, 0.880–0.983), DXA-BMD (0.996, 0.995–0.999), DXR-BMD (0.990, 0.985–0.998), DXR-porosity (1.468, 1.278–1.687) and DXR-CT (0.997, 0.996–0.999). In an adjusted model, DXR-porosity remained the only variable associated with distal radius fracture (1.415, 1.194–1.677).

Conclusion

DXR derived porosity is associated with fracture at distal radius and might be a sensitive marker for skeletal fragility.     

Interaction of chromium(III) complexes with model lipid bilayers: implications on cellular uptake

To understand molecular cytotoxicity of chromium(III) and how it affects the stability of biological membranes, studies on the interaction of chromium(III) complexes aquapentaminechromium complex (complex I) and trans- [Cr(5-methoxysalcyclohex) (H(2)O) (2)] ClO(4) (complex II) with model biomembranes have been carried out. Langmuir films of dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidic acid (DPPA), dioctadecyldimethylammoniumbromide (DOMA) at air/water interface interacting with the chromium(III) complexes have been characterized using the surface pressure-molecular area (π-A) isotherms. Initial surface pressures changes for the two complexes show that the chromium(III) complexes inserted in the Langmuir films and complex I interacted strongly compared to complex II. Supported bilayers (SB) of the lipids on solid substrates formed by hydrating their Langmuir-Blodgett films (LB films) have been characterized using linear dichroic spectra, low angle X-ray diffraction and steady state fluorescence anisotropy. Depending on the geometry of the ligands and concentration, the complexes either insert in the alkyl or in the head group region of the SB and sometimes in both regions. The Supported lipid bilayers are well-layered and at low concentration, the metal complexes are incorporated near the head group region. Order and increase in lamellar spacing show stronger interaction of complex I with the lipids compared with complex II. This study provides some insights into the mechanism of chromium(III) toxicity and uptake of chromium(III) by the cells.     

Novel approach towards recovery of glycosaminoglycans from tannery wastewater

Poly ethylene glycol (PEG)-poly acrylic acid (PAA) based aqueous two-phase system (ATPS) was selected as a practical model to recover glycosaminoglycans (GAGs) from tannery wastewater. The influence of PEG molecular weight, tie line length (TLL), pH, temperature and NaCl concentration on the partition coefficient of glycosaminoglycans from tannery wastewater was studied. Partition coefficient of glycosaminoglycan decreases on increase of PEG molecular weight, NaCl concentration and temperature, whereas it increases with increase of pH. In the PEG-rich phase, increased partitioning of GAGs was observed with increase in TLL. The partitioning of GAGs was better in PEG 4000 at pH 8.0, 20 °C with a yield of 91.50%. This study demonstrates the potential application of ATPS processes for the recovery of GAGs from complex biological suspensions.     

Studying protein degradation pathways in vivo using a cranial window-based approach

Understanding how specific proteins are degraded by neurons in living animals is a fundamental question with relevance to many neurodegenerative diseases. Dysfunction in the ubiquitin-proteasome system (UPS) specifically has been implicated in several important neurodegenerative diseases including Alzheimer's Disease, Parkinson's Disease, and amyotrophic lateral sclerosis. Research in this area has been limited by the fact that many inhibitors of the UPS given systemically do not cross the blood-brain barrier (BBB) in appreciable levels. This limits the ability to easily test in vivo specific hypotheses generated in reduced systems, like brain slice or dissociated cell culture, about whether the UPS may degrade a particular protein of interest. Although several techniques including intracerebral application via direct syringe injection, catheter-pump systems and drug-eluting beads are available to introduce BBB-impermeant drugs into brain they each have certain limitations and new approaches could provide further insights into this problem. In order to test the role of the UPS in protein degradation in vivo we have developed a strategy to treat mouse cortex with the UPS inhibitor clasto-lactacystin beta-lactone (CLBL) via a "cranial window" and recover the treated tissue for immunoblot analysis. This approach can be used in several different cranial window configurations including single window and double hemi-window arrangements that are tailored for different applications. We have also developed two different strategies for recovering treated cortical tissue including a vibratome/laser capture microscopy (LCM)-based and a vibratome only-based approach, each with its own specific advantages. We have documented UPS inhibition >600μm deep into the cortex with this strategy. This set of techniques in the living mammalian brain is complementary to previously developed approaches and extends the repertoire of tools that can be used to the study protein degradation pathways relevant to neurodegenerative disease.     

Japanese encephalitis virus: from genome to infectome

Japanese encephalitis virus (JEV) is an arbovirus belonging to the family Flaviviridae. It is maintained in a zoonotic cycle involving pigs, ardeid birds and Culex species of mosquitoes. Humans are accidental/dead end hosts of JEV infection because they cannot sustain high viral titers. Factors affecting the clinical manifestations and pathogenesis of JEV infection are not well understood. Though, vaccines are currently available against JEV, it has to be further improved. Here we review the literature on the JEV life cycle, pathogenesis and host immune responses to JEV infection.     

Decreased bone mineral density and reduced bone quality in H(+) /K(+) ATPase beta-subunit deficient mice

Proton pump inhibitors (PPIs) are widely used against gastroesophageal reflux disease. Recent epidemiological studies suggest that PPI users have an increased risk of fractures, but a causal relationship has been questioned. We have therefore investigated the skeletal phenotype in H⁺/K⁺ATPase beta‐subunit knockout (KO) female mice. Skeletal parameters were determined in 6‐ and 20‐month‐old KO mice and in wild‐type controls (WT). Whole body bone mineral density (BMD) and bone mineral content (BMC) were measured by dual energy X‐ray absorptiometry (DXA). Femurs were examined with µCT analyses and break force were examined by a three‐point bending test. Plasma levels of gastrin, RANKL, OPG, osteocalcin, leptin, and PTH were analyzed. KO mice had lower whole body BMC at 6 months (0.53 vs. 0.59 g, P = 0.035) and at 20 months (0.49 vs. 0.74 g, P < 0.01) compared to WT as well as lower BMD at 6 months (0.068 vs. 0.072 g/cm², P = 0.026) and 20 months (0.067 vs. 0.077 g/cm², P < 0.01). Mechanical strength was lower in KO mice at the age of 20 months (6.7 vs. 17.9 N, P < 0.01). Cortical thickness at 20 months and trabecular bone volume% at 6 months were significantly reduced in KO mice. Plasma OPG/RANKL ratio and PTH was increased in KO mice compared to controls. H⁺/K⁺ATPase beta subunit KO mice had decreased BMC and BMD, reduced cortical thickness and inferior mechanical bone strength. Whereas the mechanism is uncertain, these findings suggest a causal relationship between long‐term PPI use and an increased risk of fractures. J. Cell. Biochem. 113: 141–147, 2012. © 2011 Wiley Periodicals, Inc.