Br-rich tips of calcified crab claws are less hard but more fracture resistant: a comparison of mineralized and heavy-element biological materials.

We find that the spoon-like tips of the chelipeds (large claws) of the crab Pachygrapsus crassipes differ from the rest of the claw in that they are not calcified, but instead contain about 1% bromine--thus they represent a new example of a class of structural biological materials that contain heavy elements such as Zn, Mn, Fe, Cu, and Br bound in an organic matrix. X-ray absorption spectroscopy data suggest that the bromine is bound to phenyl rings, possibly in tyrosine. We measure a broad array of mechanical properties of a heavy-element biological material for the first time (abrasion resistance, coefficient of kinetic friction, energy of fracture, hardness, modulus of elasticity and dynamic mechanical properties), and we make a direct comparison with a mineralized tissue. Our results suggest that the greatest advantage of bromine-rich cuticle over calcified cuticle is resistance to fracture (the energy of fracture is about an order of magnitude greater than for calcified cuticle). The greatest advantage relative to unenriched cuticle, represented by ant mandible cuticle, is a factor of about 1.5 greater hardness and modulus of elasticity.The spoon-like tips gain additional fracture resistance from the orientation of the constituent laminae and from the viscoelasticity of the material. We suggest that fracture resistance is of greater importance in smaller organisms, and we speculate that one function of heavy elements in structural biological materials is to reduce molecular resonant frequencies and thereby increase absorption of energy from impacts.

Antimicrobial peptide coatings for hydroxyapatite: electrostatic and covalent attachment of antimicrobial peptides to surfaces.

The interface between implanted devices and their host tissue is complex and is often optimized for maximal integration and cell adhesion. However, this also gives a surface suitable for bacterial colonization. We have developed a novel method of modifying the surface at the material-tissue interface with an antimicrobial peptide (AMP) coating to allow cell attachment while inhibiting bacterial colonization. The technology reported here is a dual AMP coating. The dual coating consists of AMPs covalently bonded to the hydroxyapatite surface, followed by deposition of electrostatically bound AMPs. The dual approach gives an efficacious coating which is stable for over 12 months and can prevent colonization of the surface by both Gram-positive and Gram-negative bacteria.

Mass and shape as factors in intraocular foreign body injuries.

OBJECTIVES: To relate the nature, mass, and shape of intraocular foreign bodies (IOFBs) in a consecutive series of 69 patients to the mechanism, location, and visual outcome of the injuries and to compare these outcomes with data collected in our department over the last 70 years. DESIGN: Interventional case series of consecutive patients with IOFBs. PARTICIPANTS: Sixty-nine patients with unilateral IOFBs. INTERVENTION: All patients underwent surgical removal of the IOFB. MAIN OUTCOME MEASURES: Patient data included best-corrected visual acuity (BCVA), imaging and complication rates. For the IOFBs, material, mass, shape, and entry site were determined. RESULTS: The IOFB was metallic in 91% of cases. All but 2 patients were male (mean age, 37). Increasing IOFB mass was associated with posterior segment injury, retinal impact, presenting and final BCVAs< or =20/200, the need for a primary globe repair before secondary IOFB removal, increasing complications, and the development of retinal detachment. Blade-shaped IOFBs penetrated to the posterior segment (97%) more frequently (P<0.05) than disc (74%), cylinder (7.5%), or sphere (7.5%) shapes despite having the second lowest mass. Two patients were shown to have a second previously unrecognized IOFB on computed tomography (CT). Overall, 49% of patients experienced some sort of complication as a result of their injury. The development of endophthalmitis was associated with the failure to use prophylactic systemic antibiotics. There was no association between increased time to IOFB removal and the development of endophthalmitis. The frequency of posterior vitreous detachment was not increased in eyes with more severe injury or those in which surgery was deferred. Final BCVA> or =20/40 was achieved in 56% of the patients. CONCLUSIONS: Intraocular foreign bodies of greater mass were associated with worse outcomes. We have observed an 82% reduction in number of IOFB injuries presenting over the last 70 years and outcomes have improved with advances in surgical technique. We advise that all patients with a visible or suspected IOFB be investigated with x-ray or CT and that they should all receive systemic antibiotics. We detected no advantage or disadvantage in delaying surgery until optimal surgical expertise and/or environment is available.

Stem cell treatment of degenerative eye disease.

Stem cell therapies are being explored extensively as treatments for degenerative eye disease, either for replacing lost neurons, restoring neural circuits or, based on more recent evidence, as paracrine-mediated therapies in which stem cell-derived trophic factors protect compromised endogenous retinal neurons from death and induce the growth of new connections. Retinal progenitor phenotypes induced from embryonic stem cells/induced pluripotent stem cells (ESCs/iPSCs) and endogenous retinal stem cells may replace lost photoreceptors and retinal pigment epithelial (RPE) cells and restore vision in the diseased eye, whereas treatment of injured retinal ganglion cells (RGCs) has so far been reliant on mesenchymal stem cells (MSC). Here, we review the properties of non-retinal-derived adult stem cells, in particular neural stem cells (NSCs), MSC derived from bone marrow (BMSC), adipose tissues (ADSC) and dental pulp (DPSC), together with ESC/iPSC and discuss and compare their potential advantages as therapies designed to provide trophic support, repair and replacement of retinal neurons, RPE and glia in degenerative retinal diseases. We conclude that ESCs/iPSCs have the potential to replace lost retinal cells, whereas MSC may be a useful source of paracrine factors that protect RGC and stimulate regeneration of their axons in the optic nerve in degenerate eye disease. NSC may have potential as both a source of replacement cells and also as mediators of paracrine treatment.

Peptide aptamers: Novel coatings for orthopaedic implants.

Current processes for coating titanium implants with ceramics involve very high energy techniques with associated high cost and disadvantages such as heterogeneity of the coatings, phase transformations and inability to coat complex structures. In order to address the above problems, we propose a biomimetic hydroxyapatite coating process with the use of peptides that can bind both on titanium surfaces and hydroxyapatite. The peptides enabled homogeneous coating of a titanium surface with hydroxyapatite. The hydroxyapatite-peptide sandwich coating showed no adverse effects on cell number or collagen deposition. This makes the sandwich coated titanium a good candidate for titanium implants used in orthopaedics and dentistry.

Enteric coated HPMC capsules designed to achieve intestinal targeting.

The enteric coating of HPMC capsules containing paracetamol was investigated. Two enteric polymers, Eudragit L 30 D-55 and Eudragit FS 30 D were studied, which are designed to achieve enteric properties and colonic release, respectively. The capsules were coated in an Accela Cota 10, and, as shown by optical microscopy, resulted in capsules with a uniform coating. Scanning electron microscopy of the surface of the capsules illustrate that, in contrast to gelatin, HPMC has a rough surface, which provides for good adhesion to the coating. Dissolution studies demonstrated that capsules coated with Eudragit L 30 D-55 were gastro resistant for 2 h at pH 1.2 and capsules coated with Eudragit FS 30 D were resistant for a further 1 h at pH 6.8. The product visualisation technique of gamma scintigraphy was used to establish the in vivo disintegration properties of capsules coated with 8 mg cm(-2) Eudragit L 30 D-55 and 6 mg cm(-2) Eudragit FS 30 D. For HPMC units coated with Eudragit L 30 D-55, complete disintegration occurred predominately in the small bowel in an average time of 2.4 h post dose. For HPMC capsules coated with Eudragit FS 30 D, complete disintegration did not occur until the distal small intestine and proximal colon in an average time of 6.9 h post dose.

Reported toxicity in 1486 liquid detergent capsule exposures to the UK National Poisons Information Service 2009-2012, including their ophthalmic and CNS effects.

CONTEXT. Data on the ophthalmic and central nervous system (CNS) adverse effects of liquid detergent capsules (liquid laundry pods) are limited. OBJECTIVE. To ascertain the reported toxicity of liquid detergent capsules, particularly their ophthalmic and CNS adverse effects, in a large case series. METHODS. Between 1 May 2009 and 30 July 2012 the UK National Poisons Information Service collected prospectively 1509 telephone enquiries (involving 1486 exposures) relating to liquid detergent capsules. RESULTS. The majority of patients (95.6%) were children aged less than 5. Exposure to these products occurred mainly as a result of ingestion alone (n = 1215; 81.8%), with eye contact alone (n = 110; 7.4%), and skin contact alone (n = 20; 1.3%) being less common; multiple routes of exposure were involved in 141 (9.5%) cases. Following ocular exposure (n = 212), features suggesting conjunctivitis (n = 145; 68.4%) and corneal ulceration (n = 6; 2.8%) developed. The most common features reported following ingestion alone were nausea and vomiting (n = 721; 59.3%), followed by coughing (n = 53; 4.4%), drowsiness/CNS depression (n = 49; 42 of these were children were aged 2 years or less) and foaming at the mouth (n = 47; 3.9%). A rash occurred in 22 patients where ingestion was considered to be the route of exposure. Twenty patients were exposed via the dermal route alone and developed erythema (n = 9), rash (n = 6) and burn (n = 3). CONCLUSIONS. Ocular exposure to liquid detergent capsules may lead to conjunctivitis and corneal ulceration; detergent ingestion may result in central nervous system (CNS)depression. Greater consumer awareness is required to reduce injury from liquid detergent capsules, particularly that involving the eye.

In vitro and in vivo pharmacoscintigraphic evaluation of ibuprofen hypromellose and gelatin capsules.

PURPOSE: To evaluate the in vitro and in vivo characteristics of hypromellose (HPMC) capsules prepared using a gellan gum and potassium gelling system compared to conventional hard gelatin capsules. METHODS: The in vitro dissolution of ibuprofen gelatin and HPMC capsules was determined using the USP and TRIS buffers at pH 7.2. The effect of pH and composition of the media was determined using a model drug that is soluble throughout the pH range 1.2 to 7.2. In an 11 subject four-way crossover study, the gastrointestinal performance of ibuprofen gelatin and HPMC capsule formulations was evaluated using scintigraphy and pharmacokinetics following fasted and fed dosing. RESULTS: Acid conditions and the presence of K+ cations hinder HPMC capsule opening, whereas in water, dissolution is identical to that of gelatin. These effects are related to the nature of the gel network that is formed in the presence of cations. No significant difference in esophageal transit was observed. Although the in vivo opening times of HPMC capsules were longer than for their gelatin counterparts, no significant difference in the regulatory important pharmacokinetic metrics of C(max) and AUC was found between ibuprofen, gelatin and HPMC capsules. CONCLUSIONS: The in vitro performance of HPMC capsules differ from gelatin, which will require modification to dissolution testing methodology for certain drugs. However, for the class II BCS drug ibuprofen, the two capsule types were not statistically different when comparing AUC and C(max) values, which suggests that the in vitro differences have reduced in vivo relevance.