Polymicrobial Biofilm Inhibition Effects of Acetate‐Buffered Chitosan Sponge Delivery Device

Polymicrobial biofilm‐associated implant infections present a challenging clinical problem. Through modifications of lyophilized chitosan sponges, degradable drug delivery devices for antibiotic solution have been fabricated for prevention and treatment of contaminated musculoskeletal wounds. Elution of amikacin, vancomycin, or a combination of both follows a burst release pattern with vancomycin released above minimum inhibitory concentration for Staphylococcus aureus for 72 h and amikacin released above inhibitory concentrations for Pseudomonas aeruginosa for 3 h. Delivery of a vancomycin, amikacin, or a combination of both reduces biofilm formation on polytetrafluoroethylene catheters in an in vivo model of contamination. Release of dual antibiotics from sponges is more effective at preventing biofilm formation than single‐loaded chitosan sponges. Treatment of pre‐formed biofilm with high‐dose antibiotic release from chitosan sponges shows minimal reduction after 48 h. These results demonstrate infection‐preventive efficacy for antibiotic‐loaded sponges, as well as the need for modifications in the development of advanced materials to enhance treatment efficacy in removing established biofilm.

     

Mixed-ligand iminopyrrolato-salicylaldiminato group 4 metal complexes: Optimising catalyst structure for ethylene/propylene copolymerisations

Treatment of MCl₃(OC₆H₃-2-^tBu-6-CHNC₆F₅)(THF) (M = Ti, Zr) with a variety of different potassium iminopyrrolate salts (K⁺[RNCHC₄H₃N]⁻), (R = phenyl, cyclo-hexyl, ethyl) afforded the corresponding titanium and zirconium mixed-ligand complexes MCl₂(N-O)(N-N). The molecular structures of TiCl₂(OC₆H₃-2-^tBu-6-CHNC₆F₅)(C₂H₅NCHC₄H₃N) (1c), TiCl₂(OC₆H₃-2-^tBu-6-CHNC₆F₅)(C₆H₁₁NCHC₄H₃N) (1b) and ZrCl₂(OC₆H₃-2-^tBu-6-CHNC₆F₅)(C₆H₁₁NCHC₄H₃N) (2b) show distorted octahedral geometries with trans-O⁻,N⁻/cis-Cl₂ arrangements. On activation with MAO the titanium (iminopyrrolato)(salicylaldiminato) complexes show excellent activities in ethylene polymerisation and are significantly more effective ethylene/propylene copolymerisation catalysts, both in terms of activity and propene incorporation, than either of the parent complexes. The ethylene-propylene copolymers show ca. 80% 1,2 regioselectivity and at high propylene incorporation tend towards an alternating structure.     

Syntheses and structural characterization of heterometallic bis(pyrazolyl)methane complexes of rhenium and platinum

The new heterometallic complex {μ-1,3,5-[CH(pz)₂]₃C₆H₃}[Re(CO)₃Br][Pt(p-tolyl)₂]₂ has been prepared by reaction of 1 equiv. of the dimer [Pt(p-tolyl)₂(μ-SEt₂)]₂ with the monometallic rhenium precursor {1,3,5-[CH(pz)₂]₃C₆H₃}Re(CO)₃Br, where 1,3,5-[CH(pz)₂]₃C₆H₃ is the tritopic, arene-linked bis(pyrazolyl)methane ligand 1,3,5-tris[bis(1-pyrazolyl)methyl]benzene. Similarly, the heterometallic complex {μ-1,3,5-[CH(pz)₂]₃C₆H₃}[Re(CO)₃Br]₂[Pt(p-tolyl)₂] has been made by the reaction of the dirhenium compound {μ-1,3,5-[CH(pz)₂]₃C₆H₃}[Re(CO)₃Br]₂ and one-half of an equivalent of [Pt(p-tolyl)₂(μ-SEt₂)]₂. X-ray crystallographic studies of the new compounds reveal significant noncovalent interactions in their molecular and supramolecular structures.     

High-performance liquid affinity chromatography for the purification of immunoglobulin A from human serum using jacalin

A high-performance liquid affinity chromatographic method for the purification of serum immunoglobulin A (IgA) using a jacalin column is described. The automated procedure takes about 2 with minimal manipulation. The yields of the isolated IgA and of its IgG and IgM contamination were studied by enzyme-linked immunosorbent assay (ELISA) of 30 sera. Purity was assured by immunoelectrophoresis. The ratio of IgA1 to total IgA was unchanged after purification, as verified by ELISA. The results showed that greater than 90% IgA could be recovered with less than 0.5% total IgG and greater than 2.0% total IgM remaining in the fractions containing purified IgA.     

Inhibition of UVB-mediated oxidative stress and markers of photoaging in immortalized HaCaT keratinocytes by pomegranate polyphenol extract POMx

In recent years there has been an increase in use of botanicals with antioxidant properties as skin photoprotective agents. Pomegranate (Punica granatum L.) fruit possesses strong antioxidant and antiinflammatory properties. Recently, we have shown that pomegranate-derived products rich in anthocyanidins and ellagitannins inhibit UVB-mediated activation of nuclear factor kappa B and modulate UVA-mediated cell proliferation pathways in normal human epidermal keratinocytes. In this study, we evaluated the effect of polyphenol-rich pomegranate fruit extract (POMx) on UVB-induced oxidative stress and photoaging in human immortalized HaCaT keratinocytes. Our data show that pretreatment of HaCaT cells with POMx (10-40 microg mL(-1)) inhibited UVB (15-30 mJ cm(-2))-mediated (1) decrease in cell viability, (2) decrease in intracellular glutathione content and (3) increase in lipid peroxidation. Employing immunoblot analysis we found that pretreatment of HaCaT cells with POMx inhibited UVB-induced (1) upregulation of MMP-1, -2, -7 and -9, (2) decrease in TIMP-1, (3) phosphorylation of MAPKs and (iv) phosphorylation of c-jun, whereas no effect was observed on UVB-induced c-fos protein levels. These results suggest that POMx protects HaCaT cells against UVB-induced oxidative stress and markers of photoaging and could be a useful supplement in skin care products.     

Determination of chondroitin sulfate content in raw materials and dietary supplements by high-performance liquid chromatography with ultraviolet detection after enzymatic hydrolysis: single-laboratory validation

A method to quantify chondroitin sulfate in raw materials and dietary supplements at a range of about 5 to 100% (w/w) chondroitin sulfate has been developed and validated. The chondroitin sulfate is first selectively hydrolyzed by chondroitinase ACII enzyme to form un-, mono-, di-, and trisulfated unsaturated disaccharides; the resulting disaccharides are then quantified by ion-pairing liquid chromatography with ultraviolet detection. The amounts of the individual disaccharides are summed to yield the total amount of chondroitin sulfate in the material. Single-laboratory validation has been performed to determine the repeatability, accuracy, selectivity, limit of detection, limit of quantification, ruggedness, and linearity of the method. Repeatability precision for total chondroitin sulfate content was between 1.60 and 4.72% relative standard deviation, with HorRat values between 0.79 and 2.25. Chondroitin sulfate recovery from raw material negative control was between 101 and 102%, and recovery from finished product negative control was between 105 and 106%.     

Identification of oxidative post-translational modification of serum albumin in patients with idiopathic pulmonary arterial hypertension and pulmonary hypertension of sickle cell anemia

Pulmonary hypertension (PH) in sickle cell anemia (SCA) is characterized by decreased nitric oxide bioavailability that might, in part, be related to oxidative stress. Oxidative post-translational modifications of plasma proteins may serve as hallmarks of disease severity and could result in altered protein function and structure. We hypothesized that serum albumin in patients with PH of SCA undergoes oxidative post-translational modification and that this modification may reflect important mediators of disease pathogenesis that are common to both idiopathic pulmonary arterial hypertension (IPAH) and PH of SCA. To explore this hypothesis, we studied albumin purified from the plasma of patients in four subject groups: SCA and PH, SCA steady-state without PH, IPAH, and normal volunteers. Purified albumin was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Using MALDI-TOFMS, we identified that an ion corresponding to a malondialdehyde (MDA)-modified albumin peptide was differentially present in patients with IPAH and PH of SCA. These results were confirmed by dot-blotting and Western analysis. We localized the site of MDA modification to albumin residue K159 using LC/MS/MS. Thus, we have identified an MDA modification of serum albumin that appears to be a common link between PH of SCA and IPAH. This finding supports the notion that oxidative stress modulates the pathogenesis of PH of SCA and suggests that this and other post-translational modifications may be important biomarkers of disease.     

Micropatterns of an extracellular matrix protein with defined information content

One powerful approach to understanding how cells process spatially variant signals is based on using micropatterned substrates to control the distribution of signaling molecules. However, quantifying spatially complex signals requires an appropriate metric. Here we propose that the Shannon information theory formalism provides a robust and useful way to quantify the organization of proteins in micropatterned systems. To demonstrate the use of informational entropy as a metric, we produced patterns of lines of fibronectin with varying information content. Fibroblasts grown on these patterns were sensitive to very small changes in informational entropy (6.6 bits), and the responses depended on the scale of the pattern.