Antibacterial‐nanocomposite bone filler based on silver nanoparticles and polysaccharides

Injectable bone fillers represent an attractive strategy for the treatment of bone defects. These injectable materials should be biocompatible, capable of supporting cell growth and possibly able to exert antibacterial effects. In this work, nanocomposite microbeads based on alginate, chitlac, hydroxyapatite and silver nanoparticles were prepared and characterized. The dried microbeads displayed a rapid swelling in contact with simulated body fluid and maintained their integrity for more than 30 days. The evaluation of silver leakage from the microbeads showed that the antibacterial metal is slowly released in saline solution, with less than 6% of silver released after 1 week. Antibacterial tests proved that the microbeads displayed bactericidal effects toward Staphylococcus aureus, Pseudomonas aeruginosa and Staphylococcus epidermidis, and were also able to damage pre‐formed bacterial biofilms. On the other hand, the microbeads did not exert any cytotoxic effect towards osteoblast‐like cells. After characterization of the microbeads bioactivity, a possible means to embed them in a fluid medium was explored in order to obtain an injectable paste. Upon suspension of the particles in alginate solution or alginate/hyaluronic acid mixtures, a homogenous and time‐stable paste was obtained. Mechanical tests enabled to quantify the extrusion forces from surgical syringes, pointing out the proper injectability of the material. This novel antibacterial bone filler appears as a promising material for the treatment of bone defects, in particular when possible infections could compromise the bone‐healing process. Copyright © 2016 John Wiley & Sons, Ltd.     

A new mutation in two siblings with cystinosis presenting with Bartter syndrome

Nephropathic cystinosis is a severe autosomal recessive inherited metabolic disease characterized by accumulation of free cystine in lysosomes. Cystinosis can lead to renal failure and multiorgan impairment. Only five cases of cystinosis with associated Bartter syndrome are reported in the literature, and no genetic evaluation has been reported. We describe two siblings with nephropathic cystinosis presenting with features of Bartter syndrome and their genetic pattern.     

A study of dentofacial morphology in South Australian twins

A study of the dentofacial characteristics of South Australian twins commenced in 1983. Methods described include procedures for the acquisition, display and analysis of data in two and three dimensional formats. A preliminary account of facial asymmetry in a pair of monozygous twin boys revealed some interesting aspects of mirror-imaging and demonstrated the application of a shape-fitting routine to investigations of facial morphology.     

Changes in retrograde memory following temporal lobectomy

Extensive retrograde memory deficits have been detected in patients with temporal lobe epilepsy (TLE) and in patients who have undergone temporal lobectomy (TL). To date, no group study has used a prospective longitudinal design. We assessed memory for public and autobiographical facts and events in patients (n = 15) with focal left- or right-sided TLE before and after TL using a battery of tests that covered the life span. Patients who underwent TL demonstrated material-specific memory decline in retrograde memory. Left TL was associated with a significant drop in recall of famous people’s names. Patients who underwent right TL exhibited a significant decline in the recall of autobiographical events from across the life span. Our study indicates for the first time that TL is associated with a risk of mild, material-specific retrograde memory decline. Verifications with a larger sample size and other measures of remote memory are needed.     

Polysaccharide‐Based Polyanion–Polycation–Polyanion Ternary Systems in the Concentrated Regime and Hydrogel Form

In the field of bioactive biomaterials, multi‐biopolymer systems are of particular interest as they represent potential extra cellular matrix (ECM) mimics. Ternary mixtures composed of alginate, hyaluronan, and a lactose‐modified chitosan undergo a rheological investigation that reveal the presence of polyanion‐polycation supramolecular structures, which dissolve once the third (polyanion) component is added. Two selected ternary mixtures are used for the preparation of calcium–alginate hydrogels and their mechanical performance and stability are found to be strongly influenced by the relative composition in terms of the two non‐gelling components. The presence in the mixture of bioactive polysaccharides leads to a notable improvement in the proliferation of primary culture of chondrocytes.

     

Anchoring versus spatial filtering accounts of simultaneous lightness contrast

The oldest lightness illusion is called simultaneous contrast. A gray square placed on a black background appears lighter than an identical gray square placed on a white background. For over a hundred years, this illusion has been generally attributed to lateral inhibition or spatial filtering. Receptor cells stimulated by the gray square on the white background are strongly inhibited by nearby cells stimulated by the bright white background. Recently, a new explanation for this illusion was proposed as part of a larger theory of lightness called anchoring theory. The lightness of each target square is computed relative to the highest luminance in its local framework (consisting of only the target and its surrounding background) and relative to the highest luminance in the entire display. For each target, perceived lightness is held to depend on a weighted average of these two computations. According to this story, the contrast illusion stems mostly from the tendency of the gray square on the black background to rise toward white, its computed value in its local framework. We report six experiments in which these two theories of simultaneous contrast are pitted against each other. In each case, the results favor the anchoring model. The difficulty of deriving predictions from the spatial filtering models is discussed, along with the ease of deriving highly specific predictions from the anchoring model.