Optical coherence tomography is a valuable tool in the study of the effects of microneedle geometry on skin penetration characteristics and in-skin dissolution.

In this study, we used optical coherence tomography (OCT) to extensively investigate, for the first time, the effect that microneedle (MN) geometry (MN height, and MN interspacing) and force of application have upon penetration characteristics of soluble poly(methylvinylether-co-maleic anhydride, PMVE/MA) MN arrays into neonatal porcine skin in vitro. The results from OCT investigations were then used to design optimal and suboptimal MN-based drug delivery systems and evaluate their drug delivery profiles cross full thickness and dermatomed neonatal porcine skin in vitro. It was found that increasing the force used for MN application resulted in a significant increase in the depth of penetration achieved within neonatal porcine skin. For example, MN of 600 µm height penetrated to a depth of 330 µm when inserted at a force of 4.4 N/array, while the penetration increased significantly to a depth of 520 µm, when the force of application was increased to 16.4 N/array. At an application force of 11.0 N/array it was found that, in each case, increasing MN height from 350 to 600 µm to 900 µm led to a significant increase in the depth of MN penetration achieved. Moreover, alteration of MN interspacing had no effect upon depth of penetration achieved, at a constant MN height and force of application. With respect to MN dissolution, an approximate 34% reduction in MN height occurred in the first 15 min, with only 17% of the MN height remaining after a 3-hour period. Across both skin models, there was a significantly greater cumulative amount of theophylline delivered after 24 h from an MN array of 900 µm height (292.23 ± 16.77 µg), in comparison to an MN array of 350 µm height (242.62 ± 14.81 µg) (p < 0.001). Employing full thickness skin significantly reduced drug permeation in both cases. Importantly, this study has highlighted the effect that MN geometry and application force have upon the depth of penetration into skin. While it has been shown that MN height has an important role in the extent of drug delivered across neonatal porcine skin from a soluble MN array, further studies to evaluate the full significance of MN geometry on MN mediated drug delivery are now underway. The successful use of OCT in this study could prove to be a key development for polymeric MN research, accelerating their commercial exploitation.

A fish bradykinin (Arg0; Trp5; Leu8-bradykinin) from the defensive skin secretion of the European edible frog; Pelophylax kl. esculentus: structural characterization; molecular cloning of skin kininogen cDNA and pharmacological effects on mammalian smooth muscle

Extensive studies on bradykinin-related peptides (BRPs) generated from plasma kininogens in representative species of various vertebrate taxa, have confirmed that many amphibian skin BRPs reflect those present in putative vertebrate predators. For example, the (Val1, Thr6)-bradykinin, present in the defensive skin secretions of many ranids and phyllomedusines, can be generated from plasma kininogens in colubrid snakes - common predators of these frogs. Here, we report the presence of (Arg0, Trp5, Leu8)-bradykinin in the skin secretion of the European edible frog, Pelophylax kl. esculentus, and have found it to be encoded in single copy by a kininogen with an open-reading frame of 68 amino acid residues. This peptide is the archetypal bony fish bradykinin that has been generated from plasma kininogens of the bowfin (Amia calva), the long-nosed gar (Lepisosteus oseus) and the rainbow trout (Onchorhynchus mykiss). More recently, this peptide has been shown to be encoded within cloned kininogens of the Atlantic cod (Gadus morhua) spotted wolf-fish (Anarichas minor), zebrafish (Danio rerio), pufferfish (Tetraodon nigroviridis) and Northern pike (Esox lucius). The latter species is regarded as a major predator of P. kl. esculentus. Synthetic (Arg0, Trp5, Leu8)-bradykinin was previously reported as having multiphasic effects on arterial blood pressure in conscious trout and here we have demonstrated that it can antagonize the relaxation in rat arterial smooth muscle induced by canonical mammalian bradykinin. The discovery of (Arg0, Trp5, Leu8)-bradykinin in the defensive skin secretion of this amphibian completes the spectrum of vertebrate taxon-specific BRPs identified from this source.

Fatigue performance of aircraft panels with novel skin buckling containment features

To increase structural efficiency of stiffened panels in an aircraft, it is plausible to introduce skin buckling containment features to increase the local skin stability and thus static strength performance. Introducing buckling containment features may also significantly influence the fatigue crack growth performance of the stiffened panel. This study focuses on the experimental demonstration of panel durability with skin bay buckling containment features. Through a series of fatigue crack growth tests on integrally machined aluminium alloy stiffened panels, the potential to simultaneously improve static strength performance and crack propagation behaviour is demonstrated. The introduction of prismatic buckling containment features which have yielded significant static strength performance gains have herein demonstrated potential fatigue life gains of up to + 63 per cent.

Fixed-dose combination therapy for type 2 diabetes: sitagliptin plus pioglitazone

Importance of the field: Type 2 diabetes is typically associated with insulin resistance and dysfunction of insulin-secreting pancreatic beta-cells. Addressing these defects often requires therapy with a combination of differently acting antidiabetic agents. A potential novel combination in development brings together the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin with the thiazolidinedione pioglitazone into a fixed-dose single-tablet combination. The former component acts mainly to increase prandial insulin secretion; the latter improves insulin sensitivity.

Kassorins: Novel innate immune system peptides from skin secretions of the African hyperoliid frogs, Kassina maculata and Kassina senegalensis

From defensive skin secretions acquired from two species of African hyperoliid frogs, Kassina maculata and Kassina senegalensis, we have isolated two structurally related, C-terminally amidated tridecapeptides of novel primary structure that exhibit a broad spectrum of biological activity. In reflection of their structural novelty and species of origin, we named the peptides kassorin M (FLEGLLNTVTGLLamide; 1387.8 Da) and kassorin S (FLGGILNTITGLLamide; 1329.8 Da), respectively. The primary structure and organisation of the biosynthetic precursors of kassorins M and S were deduced from cloned skin secretion-derived cDNA. Both open-reading frames encoded a single copy of kassorin M and S, respectively, located at the C-terminus. Kassorins display limited structural similarities to vespid chemotactic peptides (7/13 residues), temporin A (5/13 residues), the N-terminus of Lv-ranaspumin, a foam nest surfactant protein of the frog, Leptodactylus vastus, and an N-terminal domain of the equine sweat surfactant protein, latherin. Both peptides elicit histamine release from rat peritoneal mast cells. However, while kassorin S was found to possess antibacterial activity against Staphylococcus aureus, kassorin M was devoid of such activity. In contrast, kassorin M was found to contract the smooth muscle of guinea pig urinary bladder (EC50 = 4.66 nM) and kassorin S was devoid of this activity. Kassorins thus represent the prototypes of a novel family of peptides from the amphibian innate immune system as occurring in defensive skin secretions.

Dose-dependent effects of folic acid on blood concentrations of homocysteine: a meta-analysis of the randomized trials

Background: Dietary supplementation with B vitamins that lower blood homocysteine concentrations is expected to reduce cardiovascular disease risk, but there has been uncertainty about the optimum regimen to use for this purpose.