Antifungal Activity of Synthetic Scorpion Venom-Derived Peptide Analogues Against Candida albicans

Fungal infections are becoming a serious problem due to their high morbidity and mortality combined with the rise in drug resistance and dearth of new antimycotic drugs. The scorpion venom-derived peptide BmKn2, and its synthetic analogue Kn2–7, were previously observed to have antibacterial activity. These peptides and their d-amino acid analogues (dBmKn2 and dKn2–7) were tested for antifungal activity against drug resistant and clinical isolates of Candida albicans. In planktonic susceptibility studies, dKn2–7 had greater activity than the other three peptides against 6 out of 7 fungal strains, with no apparent correlation between drug resistance and minimum fungicidal concentrations (MFCs). Time kill experiments demonstrated that the fungicidal activity of dKn2–7 began within the first hour and killing rates were dose dependent at ≥ 1 × MFC. Against biofilms, the d-analogues were the most effective, while the l-analogues had low efficacy in most strains even at 10 times the planktonic MFC. Stability testing suggests that this increased efficacy of the d-analogues may be due to increased resistance to protease degradation compared to the l-analogues. Peptides were also assessed for mammalian cell toxicity. BmKn2 and dBmKn2 induced significant hemolysis at levels similar to their MFCs, whereas Kn2–7 and dKn2–7 caused hemolysis at 4–16 times their MFCs. The 50% inhibitory concentration (IC50) for dKn2–7 against murine fibroblasts was greater than or equal to the planktonic MFCs and biofilm IC50s for dKn2–7 in all C. albicans strains tested. These results support the potential for dKn2–7 to be further investigated as a novel antifungal therapeutic.

Extrudable salicylic acid-based poly(anhydride-esters) for injectable drug releasing applications

Injectable biomaterials have attracted more and more interest owing to their advantages over traditional open surgeries: minimal invasive procedure and ease of handling. Commonly used synthetic injectable polymers exhibited low drug loading and poor biodegradability. In this work, we describe a novel series of degradable copolymers comprising salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) subunits suitable for injectable drug releasing applications. By tuning the rheology properties, these salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) copolymers may function as injectable drug delivery vehicles that deliver salicylic acid at the injury site. These copolymers were designed to have glass transition temperatures (Tg) below 0ºC, resulting in extrudable polymers that behave like viscous fluids at room temperature. Salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol) copolymers of different ratios (2:1, 1:1, and 1:2 salicylic acid–based poly(anhydride-esters) and poly(ethylene glycol)) were synthesized and characterized by nuclear magnetic resonance and Fourier-transform infrared spectroscopies. Their shear viscosities were determined both at room and physiological temperatures. The in vitro drug release profiles, cytotoxicity, and anti-inflammatory activities were assessed. The shear viscosities were found to compare favorably with current injectable barrier materials on the market.

In Vitro Degradation of an Aromatic Polyanhydride with Enhanced Thermal Properties

Polyanhydrides have been studied as a drug delivery vehicles due to their surface-eroding behavior which results in zero-order release. However, many polyanhyrides have thermal and solubility properties that make them difficult to formulate for these applications. Poly[α,α'-bis(ortho-carboxyphenoxy)-para-xylene] (oCPX) is an aromatic polyanhydride that has thermal and solubility properties enabling facile processing. The polymer's in vitro degradation profile exhibited an induction period up to 10 days in which degradation product concentration in the media was minimal, followed by a period of stable release of the biocompatible degradation product. Scanning electron microscope images and molecular weight changes of the polymer matrices confirm that this polymer is primarily surface-eroding. The combination of thermal properties, solubility, polymer degradation time, and erosion mechanism indicate that poly(oCPX) is be a suitable matrix candidate for extended, controlled drug delivery.

Poly(anhydride-ester) and poly(N-vinyl-2-pyrrolidone) blends: salicylic acid-releasing blends with hydrogel-like properties that reduce inflammation

Polymers such as poly(N-vinyl-2-pyrrolidone) (PVP) have been used to prepare hydrogels for wound dressing applications but are not inherently bioactive. For enhanced healing, PVP was blended with salicylic acid-based poly(anhydride-esters) (SAPAE) and shown to exhibit hydrogel properties upon swelling. In vitro release studies demonstrated that the chemically incorporated drug (SA) was released from the polymer blends over 3-4 d in contrast to 3 h, and that blends of higher PVP content displayed greater swelling values and faster SA release. The polymer blends significantly the inflammatory cytokine, TNF-α, in vitro without negative effects.

Tunable drug release profiles from salicylate-based poly(anhydride-ester) matrices using small molecule admixtures

Poly(anhydride-esters) with salicylic acid, a nonsteroidal anti-inflammatory drug, chemically incorporated into the polymer backbone provide high inherent drug loading. These poly(anhydride-esters) hydrolytically degrade to release salicylic acid over extended time periods (>30 days); however, an initial lag period of no salicylic acid release is observed. This lag period could be unfavorable in applications where immediate salicylic acid release is desired. Poly(anhydride-esters) with short (2 days) and long (11 days) lag periods were admixed with various small molecules as a means to shorten or eliminate the lag period. Salicylic acid, larger salicylic acid prodrugs, and 1:1 combinations of the two were physically admixed, each at 1%, 5%, and 10% (w/w). All admixtures resulted in immediate salicylic acid release and a decrease in glass transition temperatures compared to polymer alone. By varying the amounts of salicylic acid and salicylic acid prodrugs incorporated into the polymer matrix, immediate and constant salicylic acid release profiles over varied time periods were achieved.

Memory for sex-role consistent and inconsistent actions in young and old adults

Adult age differences in the flexibility of schematic processing were examined by measuring the degree to which a dominant structure (traditional sex-role knowledge) interfered with the operation of a nondominant structure (nontraditional knowledge). In two experiments, young and old adults read statements describing a man performing actions consistent or inconsistent with a prescribed sex role in an impression-formation task. Participants in both age groups altered their processing of the actions, as indicated by reading times and trait ratings, relative to the sex role emphasized, although the effect was stronger for men than women. The expected greater recall for sex role inconsistent than consistent actions was observed only when the traditional sex role was emphasized, and not when the nontraditional role was emphasized, suggesting interference from the dominant schema at recall. However, the lack of age differences in the degree of interference observed during initial processing and recall suggests no aging effects on schematic flexibility.

Phases of transition in cognitive development: evidence from the domain of spatial representation

Data on changes in children's map drawing ability are used to examine 3 hypotheses concerning the relationship of level mixture to developmental change as proposed by Damon in a recent study of social reasoning: (1) that high total mixture precedes change, (2) that low total mixture precedes change, and (3) that high positive mixture (i.e., that at stages above the mode) precedes change. Further predictions are derived from our 6-phase model of transition; these are compared and contrasted with conclusions reached by Damon. Using Damon's approach, we replicate his finding that high positive mixture precedes model advance. More detailed analyses of 2 separate groups as suggested by the transitions model, however, show that all 3 types of mixture precede developmental change, albeit different types of change within each group.

The effects of modeling and cognitive induction on the moral reasoning of adolescents

In this investigation of the effects of modeling and cognitive induction on moral reasoning, 87 junior high school students were exposed to moral reasoning, characteristic of either one stage above (+1) or one stage below (-1) their dominant stage, as determined by pretesting. The presented reasoning was attributed to a model of either high, neutral, or low status/relevance to the content of the moral dilemmas used. A multiple-choice adaptation of the Kohlberg moral development interview was used at pretesting, at intervention/posttesting, and at delayed posttesting. Analyses of changes in moral reasoning included examination of direct and indirect effects on both an immediate and a delayed posttest. Results indicated significant and stable change in moral reasoning associated with the developmental stage of the message (+1 produced advances, but -1 failed to induce significant regression) and significant temporary change associated with the characteristics of the model (high status/relevance models had greater influence than did neutral models). It is suggested that future research and educational efforts give attention to both the moral stage of the intervention and the nature of the source to which it is attributed.