The Nitrobenzoxadiazole Derivative NBDHEX Behaves as Plasmodium falciparum Gametocyte Selective Inhibitor with Malaria Parasite Transmission Blocking Activity.

This work describes the activity of 6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol (NBDHEX) and of its newly identified carboxylic acid metabolite on the human malaria parasite Plasmodium falciparum. NBDHEX has been previously identified as a potent cytotoxic agent against murine and human cancer cells as well as towards the protozoan parasite Giardia duodenalis. We show here that NBDHEX is active in vitro against all blood stages of P. falciparum, with the rare feature of killing the parasite stages transmissible to mosquitoes, the gametocytes, with a 4-fold higher potency than that on the pathogenic asexual stages. This activity importantly translates into blocking parasite transmission through the Anopheles vector in mosquito experimental infections. A mass spectrometry analysis identified covalent NBDHEX modifications in specific cysteine residues of five gametocyte proteins, possibly associated with its antiparasitic effect. The carboxylic acid metabolite of NBDHEX retains the gametocyte preferential inhibitory activity of the parent compound, making this novel P. falciparum transmission-blocking chemotype at least as a new tool to uncover biological processes targetable by gametocyte selective drugs. Both NBDHEX and its carboxylic acid metabolite show very limited in vitro cytotoxicity on VERO cells. This result and previous evidence that NBDHEX shows an excellent in vivo safety profile in mice and is orally active against human cancer xenografts make these molecules potential starting points to develop new P. falciparum transmission-blocking agents, enriching the repertoire of drugs needed to eliminate malaria.

Halogen-Mediated Partial Oxidation of Polyvinyl Alcohol for Tissue Engineering Purposes.

Partial oxidation of polyvinyl alcohol (PVA) with potassium permanganate turned out to be an efficient method to fabricate smart scaffolds for tissue engineering, endowed with biodegradation and protein delivery capacity. This work considered for the first time the use of halogens (bromine, chlorine and iodine) as less aggressive agents than potassium permanganate to perform controlled PVA oxidation, in order to prevent degradation of polymer molecular size upon chemical modification. Oxidized PVA solutions were chemically characterized (i.e., dinitrophenylhydrazine assay, viscosity measurements, molecular size distribution) before preparing physically cross-linked hydrogels. Scaffolds were assessed for their mechanical properties and cell/tissue biocompatibiliy through cytotoxic extract test on IMR-90 fibroblasts and subcutaneous implantation into BALB/c mice. According to chemical investigations, bromine and iodine allowed for minor alteration of polymer molecular weight. Uniaxial tensile tests demonstrated that oxidized scaffolds had decreased mechanical resistance to deformation, suggesting tunable hydrogel stiffness. Finally, oxidized hydrogels exhibited high biocompatibility both in vitro and in vivo, resulting neither to be cytotoxic nor to elicit severe immunitary host reaction in comparison with atoxic PVA. In conclusion, PVA hydrogels oxidized by halogens were successfully fabricated in the effort of adapting polymer characteristics to specific tissue engineering applications.

Development of Oxidized Polyvinyl Alcohol-Based Nerve Conduits Coupled with the Ciliary Neurotrophic Factor.

Functionalized synthetic conduits represent a promising strategy to enhance peripheral nerve regeneration by guiding axon growth while delivering therapeutic neurotrophic factors. In this work, hollow nerve conduits made of polyvinyl alcohol partially oxidized with bromine (OxPVA_Br2) and potassium permanganate (OxPVA_KMnO4) were investigated for their structural/biological properties and ability to absorb/release the ciliary neurotrophic factor (CNTF). Chemical oxidation enhanced water uptake capacity of the polymer, with maximum swelling index of 60.5% ± 2.5%, 71.3% ± 3.6% and 19.5% ± 4.0% for OxPVA_Br2, OxPVA_KMnO4 and PVA, respectively. Accordingly, hydrogel porosity increased from 15.27% ± 1.16% (PVA) to 62.71% ± 8.63% (OxPVA_Br2) or 77.50% ± 3.39% (OxPVA_KMnO4) after oxidation. Besides proving that oxidized PVA conduits exhibited mechanical resistance and a suture holding ability, they did not exert a cytotoxic effect on SH-SY5Y and Schwann cells and biodegraded over time when subjected to enzymatic digestion, functionalization with CNTF was performed. Interestingly, higher amounts of neurotrophic factor were detected in the lumen of OxPVA_Br2 (0.22 ± 0.029 µg) and OxPVA_KMnO4 (0.29 ± 0.033 µg) guides rather than PVA (0.11 ± 0.021 µg) tubular scaffolds. In conclusion, we defined a promising technology to obtain drug delivery conduits based on functionalizable oxidized PVA hydrogels.

Anticancer Gold(III) Peptidomimetics: From Synthesis to in vitro and ex vivo Biological Evaluations.

Five new AuIII -peptidodithiocarbamato complexes of the type [AuIII Br2 (dtc-AA1 -AA2 -OR] (in which AA1 =N-methylglycine (Sar), l/d-Pro; AA2 =l/d-Ala, α-aminoisobutyric acid (Aib); R=OtBu, triethylene glycol methyl ether), differing with regard to the amino acid sequence and/or the chiral amino acid configuration, were designed to enhance tumor selectivity and bioavailability. The gold(III)-based moiety was functionalized to exploit the targeting properties of the peptidomimetic ligand toward two peptide transporters (namely PEPT1 and PEPT2), which are upregulated in several tumor cells. The compounds were synthesized and fully characterized, mainly by means of elemental analysis, one- and two-dimensional NMR spectroscopy, FT-IR, and UV/Vis spectrophotometry. The crystal structures of three compounds were also solved by X-ray diffraction. In vitro cytotoxicity studies using a panel of human tumor cell lines (A549 [non-small-cell lung carcinoma], MCF-7 [breast cancer], A2780 [ovarian carcinoma], H1975 [non-small-cell lung carcinoma], H460 [large-cell lung carcinoma], and A431 [human epidermoid carcinoma]) showed the dtc-Pro-Aib-OtBu derivative to be very effective, with GI50 values much lower than those of cisplatin. This complex was thus selected for evaluating stability under physiological conditions and possible interactions with serum albumin, as well in PARP-1 enzyme inhibition assays and preliminary ex vivo toxicity experiments on healthy rat tissues.

Partially oxidized polyvinyl alcohol conduitfor peripheral nerve regeneration.

Surgical reconstruction of peripheral nerves injuries with wide substance-loss is still a challenge. Many studies focused on the development of artificial nerve conduits made of synthetic or biological materials but the ideal device has not yet been identified. Here, we manufactured a conduit for peripheral nerve regeneration using a novel biodegradable hydrogel we patented that is oxidized polyvinyl alcohol (OxPVA). Thus, its characteristics were compared with neat polyvinyl alcohol (PVA) and silk-fibroin (SF) conduits, through in vitro and in vivo analysis. Unlike SF, OxPVA and neat PVA scaffolds did not support SH-SY5Y adhesion and proliferation in vitro. After implantation in rat model of sciatic nerve transection, the three conduits sustained the regeneration of the injured nerve filling a gap of 5 mm in 12 weeks. Implanted animals showed a good gait recovery. Morphometric data related to the central portion of the explanted conduit interestingly highlighted a significantly better outcome for OxPVA scaffolds compared to PVA conduits in terms of axon density, also with respect to the autograft group. This study suggests the potential of our novel biomaterial for the development of conduits for clinical use in case of peripheral nerve lesions with substance loss.

Partially oxidized polyvinyl alcohol as a promising material for tissue engineering.

The desired clinical outcome after implantation of engineered tissue substitutes depends strictly on the development of biodegradable scaffolds. In this study we fabricated 1% and 2% oxidized polyvinyl alcohol (PVA) hydrogels, which were considered for the first time for tissue-engineering applications. The final aim was to promote the protein release capacity and biodegradation rate of the resulting scaffolds in comparison with neat PVA. After physical crosslinking, characterization of specific properties of 1% and 2% oxidized PVA was performed. We demonstrated that mechanical properties, hydrodynamic radius of molecules, thermal characteristics and degree of crystallinity were inversely proportional to the PVA oxidation rate. On the other hand, swelling behaviour and protein release were enhanced, confirming the potential of oxidized PVA as a protein delivery system, besides being highly biodegradable. Twelve weeks after in vivo implantation in mice, the modified hydrogels did not elicit severe inflammatory reactions, showing them to be biocompatible and to degrade faster as the degree of oxidation increased. According to our results, oxidized PVA stands out as a novel biomaterial for tissue engineering that can be used to realize scaffolds with customizable mechanical behaviour, protein-loading ability and biodegradability. Copyright © 2015 John Wiley & Sons, Ltd.

Thiol-Activated Anticancer Agents: The State of the Art.

The thiol or sulfhydryl group, as part of low molecular weight non-peptide biomolecules, as well as part of the cysteine residues in peptides and proteins, is known to play extremely important roles in several aspects of cellular function. Glutathione (γ-Glu-Cys-Gly; GSH) is the most abundant thiol-containing peptide in mammals, being present intracellularly in the low millimolar concentration range, but only in the low micromolar concentration range in the majority of extracellular fluids. Notably, intracellular levels of GSH have been found to be significantly upregulated in a number of human cancers, a phenomenon thought to contribute, in concert with overexpression of some GSHassociated enzymes, to the development of tumor cell chemo- and radioresistance. On the other hand, various natural and synthetic chemical entities of different sizes show significant cytotoxic activity only upon interaction with a thiol, and can therefore exploit the GSH-rich intracellular environment of tumors. This review article attempts to summarize the current structural and pharmacological knowledge in the field of thiol-activated anticancer agents, with a focus on the mechanism(s) of their activation. Even though a great part of the available thiol-activated anticancer compounds is still in the preclinical phase of testing, some of them are undergoing trials in cancer patients.

In vitro assessment of TAT - Ciliary Neurotrophic Factor therapeutic potential for peripheral nerve regeneration.

In regenerative neurobiology, Ciliary Neurotrophic Factor (CNTF) is raising high interest as a multifunctional neurocytokine, playing a key role in the regeneration of injured peripheral nerves. Despite its promising trophic and regulatory activity, its clinical application is limited by the onset of severe side effects, due to the lack of efficient intracellular trafficking after administration. In this study, recombinant CNTF linked to the transactivator transduction domain (TAT) was investigated in vitro and found to be an optimized fusion protein which preserves neurotrophic activity, besides enhancing cellular uptake for therapeutic advantage. Moreover, a compelling protein delivery method was defined, in the future perspective of improving nerve regeneration strategies. Following determination of TAT-CNTF molecular weight and concentration, its specific effect on neural SH-SY5Y and PC12 cultures was assessed. Cell proliferation assay demonstrated that the fusion protein triggers PC12 cell growth within 6h of stimulation. At the same time, the activation of signal transduction pathway and enhancement of cellular trafficking were found to be accomplished in both neural cell lines after specific treatment with TAT-CNTF. Finally, the recombinant growth factor was successfully loaded on oxidized polyvinyl alcohol (PVA) scaffolds, and more efficiently released when polymer oxidation rate increased. Taken together, our results highlight that the TAT domain addiction to the protein sequence preserves CNTF specific neurotrophic activity in vitro, besides improving cellular uptake. Moreover, oxidized PVA could represent an ideal biomaterial for the development of nerve conduits loaded with the fusion protein to be delivered to the site of nerve injury.

Autologous chondrocytes as a novel source for neo-chondrogenesis in haemophiliacs.

Haemophilic arthropathy is the major cause of disability in patients with haemophilia and, despite prophylaxis with coagulation factor concentrates, some patients still develop articular complications. We evaluate the feasibility of a tissue engineering approach to improve current clinical strategies for cartilage regeneration in haemophiliacs by using autologous chondrocytes (haemophilic chondrocytes; HaeCs). Little is known about articular chondrocytes from haemophilic patients and no characterisation has as yet been performed. An investigation into whether blood exposure alters HaeCs should be interesting from the perspective of autologous implants. The typical morphology and expression of specific target genes and surface markers were therefore assessed by optical microscopy, reverse transcription plus the polymerase chain reaction (PCR), real-time PCR and flow-cytometry. We then considered chondrocyte behaviour on a bio-hybrid scaffold (based on polyvinyl alcohol/Wharton's jelly) as an in vitro model of articular cartilage prosthesis. Articular chondrocytes from non-haemophilic donors were used as controls. HaeC morphology and the resulting immunophenotype CD44(+)/CD49c(+)/CD49e(+)/CD151(+)/CD73(+)/CD49f(-)/CD26(-) resembled those of healthy donors. Moreover, HaeCs were active in the transcription of genes involved in the synthesis of the extracellular matrix proteins of the articular cartilage (ACAN, COL1A, COL2A, COL10A, COL9A, COMP, HAS1, SOX9), although the over-expression of COL1A1, COL10A1, COMP and HAS was observed. In parallel, the composite scaffold showed adequate mechanical and biological properties for cartilage tissue engineering, promoting chondrocyte proliferation. Our preliminary evidence contributes to the characterisation of HaeCs, highlighting the opportunity of using them for autologous cartilage implants in patients with haemophilia.

Tailored PVA/ECM scaffolds for cartilage regeneration.

Articular cartilage lesions are a particular challenge for regenerative medicine due to cartilage low self-ability repair in case of damage. Hence, a significant goal of musculoskeletal tissue engineering is the development of suitable structures in virtue of their matrix composition and biomechanical properties. The objective of our study was to design in vitro a supporting structure for autologous chondrocyte growth. We realized a biohybrid composite scaffold combining a novel and nonspecific extracellular matrix (ECM), which is decellularized Wharton's jelly ECM, with the biomechanical properties of the synthetic hydrogel polyvinyl alcohol (PVA). Wharton's jelly ECM was tested for its ability in promoting scaffold colonization by chondrocytes and compared with polyvinyl alcohol itself and the more specific decellularized cartilage matrix. Our preliminary evidences highlighted the chance of using Wharton's jelly ECM in combination with PVA hydrogels as an innovative and easily available scaffold for cartilage restoration.

Evaluation of vascular grafts based on polyvinyl alcohol cryogels.

The present study designed and developed blood vessel substitutes (BVSs) composed of polyvinyl alcohol (PVA) cryogels. The in vitro results demonstrated that the coating of the polymer with lyophilized decellularized vascular matrix (DVM) greatly enhanced the adhesion of human umbilical vein endothelial cells (HUVECs). However, when PVA̸DVM BVSs were implanted into the abdominal aorta of Sprague­Dawley rats, DVM was identified as a highly thrombogenic surface resulting in the mortality of all animals 3­4 days after surgery. By contrast, all rats implanted with PVA survived and were sacrificed after 12 months. The luminal surface of the explanted grafts was completely covered by endothelial cells and the inner diameter was similar to that of the original vessel. In conclusion, the present study indicated that PVA may be considered as a promising biomaterial for the fabrication of artificial vessels.

ECM-based triple layered scaffolds for vascular tissue engineering.

The present study focused on the development of three layered small-diameter (<6 mm) extracellular matrix (ECM)-based vessels. These were engineered artificially through the freeze-drying technique. A layer of decellularized bovine aorta (DAM) was deposited on a mandrel and, after lyophilization, it was dipped into a poly-L-lactide acid (PLLA)/polyethylene glycol (PEG) 2000 dichloromethane solution then quickly wrapped with a pre-prepared thin DAM sheet. Mechanical properties of three-layered scaffolds were evaluated by means of uniaxial tensile measurement. Furthermore, human endothelial and smooth muscle cells were seeded on internal and external scaffold surfaces, respectively, and co-cultured for 7 days. Our results demonstrate that i) ECM components provide suitable stimuli for cell adhesion and proliferation, ii) the microporous intermediate PLLA/PEG2000 layer is responsible for the scaffold resistance and iii) the layered deposition technique can be considered a valuable method to obtain layered vascular scaffolds of different sizes and with a good compromise between stiffness and elasticity for optimal cell organization.

Photoreactivity of 5-fluorouracil under UVB light: photolysis and cytotoxicity studies.

The photodegradation of the chemotherapeutic agent 5-fluorouracil (5-FU) under UVB light was studied both in aqueous and methanol solutions and in systemic and topical formulations. As monitored by HPLC, photodegradation in solution takes place in a concentration dependent manner; thus, the solution for parenteral administration (10(-1) M) showed negligible loss of the active principle. On the contrary, the commercial cream containing 5% of 5-FU showed low stability under UVB exposure. When dissolved either in water or methanol, 5-FU yields two photoproducts which have been characterized as two isomers coming from the addition of the solvent to the 5,6 double bond of the drug. As a consequence, photomodified 5-FU loses its antiproliferative activity on HCT-15 and HeLa cells. MS analysis showed that photoaddition occurred with nucleophilic amino acids, such as cysteine and serine, while susceptible amino acids (cysteine and methionine) were oxidized. In fact, high production of the superoxide anion under UVB light as well as photooxidation of BSA suggests protein photodamage as a mechanism of photosensitization. Indeed, some phototoxicity was shown in experiments on NCTC keratinocytes and MCF-7 resistant cells irradiated with UVB light. The interactions with these biological targets may contribute to skin phototoxicity and photoallergy induced by 5-FU in vivo.

Decellularized bovine reinforced vessels for small-diameter tissue-engineered vascular grafts.

The aim of the present study was to investigate the influence of a decellularization protocol on the structure and the mechanical behavior of small-diameter (<6 mm) tibial calf arteries and veins. Calf vessels were decellularized by a detergent-enzymatic method (DEM), partially hydrolyzed with trypsin and subsequently cross-linked using poly(ethylene glycol) diglycidyl ether. Our results showed that i) the DEM can be considered a simple and valuable procedure for the preparation of complete acellular arteries and veins able to preserve a high degree of collagen and elastic fibers, and ii) poly(ethylene glycol) diglycidyl ether cross-linking treatment provides appropriate mechanical reinforcement of blood vessels. Histologically, the decellularized vessels were obtained employing the detergent-enzymatic procedure and their native extracellular matrix histoarchitecture and components remained well preserved. Moreover, the decellularization protocol can be considered an effective method to remove HLA class I antigen expression from small-diameter tibial calf arteries and veins. Cytocompatibility of decellularized cross-linked vessels was evaluated by endothelial and smooth muscle cell seeding on luminal and adventitial vessel surfaces, respectively.

Porous alginate/poly(ε-caprolactone) scaffolds: preparation, characterization and in vitro biological activity.

In bone tissue engineering, scaffolds with controlled porosity are required to allow cell ingrowth, nutrient diffusion and sufficient formation of vascular networks. The physical properties of synthetic scaffolds are known to be dependent on the biomaterial type and its processing technique. In this study, we demonstrate that the separation phase technique is a useful method to process poly(ε-caprolactone) (PCL) into a desired shape and size. Moreover, using poly(ethylene glycol), sucrose, fructose and Ca2+ alginate as porogen agents, we obtained PCL scaffolds with three-dimensional porous structures characterized by different pore size and geometry. Scanning electron microscopy and porosity analysis indicated that PCL scaffolds prepared with Ca2+ alginate threads resemble the porosity and the homogeneous pore size distribution of native bone. In parallel, MicroCT analysis confirmed the presence of interconnected void spaces suitable to guarantee a biological environment for cellular growth, as demonstrated by a biocompatibility test with MC3T3-E1 murine preosteoblastic cells. In particular, scaffolds prepared with Ca2+ alginate threads increased adhesion and proliferation of MC3T3-E1 cells under basal culture conditions, and upon stimulation with a specific differentiation culture medium they enhanced the early and later differentiated cell functions, including alkaline phosphatase activity and mineralized extracellular matrix production. These results suggest that PCL scaffolds, obtained by separation phase technique and prepared with alginate threads, could be considered as candidates for bone tissue engineering applications, possessing the required physical and biological properties.

UVB photolysis of betamethasone and its esters: characterization of photoproducts in solution, in pig skin and in drug formulations.

The stability of the synthetic glucocorticosteroid betamethasone under UVB light was studied both in vitro (water and methanol solution and in topical and injectable commercial formulations) and ex vivo (pig skin). From irradiated methanol solutions three main photoproducts were isolated by HPLC and TLC and characterized by NMR/MS analyses. The modifications involve parts of the molecule peculiar for the therapeutic activity, that is, rearrangement of ring A ("lumi"- and "photolumiderivatives"), and Norrish Type I fragmentation of the ketolic chain ("androderivative"). Two clinically used esters of betamethasone were also studied, namely the 17-valerate and 21-phosphate, and their photoproducts identified. The HPLC method developed for the photolysis studies in solution was also applied to the analysis of commercial formulations. In a cream and a solution for parenteral use, betamethasone highly decomposed under UVB irradiation, even in the presence of the bactericidal agents chlorocresol and phenol, which are able to absorb part of the incoming radiation. As a model for the UV exposed skin to which the drug is applied, ex vivo pig skin was used; not only the yield of photodegradation was evaluated, but the photoproducts were also identified. A test on THP-1 cells demonstrated the loss of anti-inflammatory activity of betamethasone, when modified by UVB light.

Photoaddition of fluphenazine to nucleophiles in peptides and proteins. Possible cause of immune side effects.

By the action of UVA light, fluphenazine reacted with nucleophiles through a mechanism involving defluorination of its trifluoromethyl group, giving rise to carboxylic acid derivatives that were easily detected by electrospray mass spectrometry. This photoreaction took place with alcohols, sulphydryls, and amines. When irradiation of fluphenazine was carried out in the presence of an amino acid at pH 7.4, the alpha-amino group was covalently bound to the drug. With amino acids possessing a further nucleophilic residue on the side chain, such as lysine, tyrosine, and cysteine--but not serine--both groups reacted, resulting in a fluphenazine-amino acid-fluphenazine diadduct. The same occurred with the physiological peptide glutathione (gamma-glutamylcysteinylglycine). By means of MALDI mass spectrometry, it was shown that fluphenazine also covalently bound to peptides and proteins such as calmodulin. This binding may result in the formation of antibodies, ultimately leading to the destruction of the granulocytes and thus suggesting that photoactivation of this drug may play a role in its clinical side effects, such as agranulocytosis.

Novel monodisperse PEG-dendrons as new tools for targeted drug delivery: synthesis, characterization and cellular uptake.

Dendrimers, dendrons, and hyperbranched polymers are gaining popularity as novel drugs, imaging agents, and drug delivery systems. They present advantages of well-defined molecular weight, multivalent surfaces, and high drug carrying capacity. Moreover, it is emerging that such architectures can display unique endocytic properties. As poly(ethylene glycol) (PEG) is widely used for protein and drug conjugation, the aim of this study was for the first time to synthesize novel, branched PEG-based architectures, to define their cytotoxicity and, via preparation of Oregon green (OG) conjugates define the effect of structure on their cellular uptake. Five PEG-based dendrons were synthesized using monodisperse Fmoc-amino PEG propionic acid (M(w) = 840) as a monomer, and cadaverine, tris(2-aminoethyl)amine or lysine as the branching moieties. These were diamino,bisPEG (M(w) = 1300); triamino,trisPEG (Mw = 1946); tetraamino,tetraPEG (M(w) = 3956); monocarboxy,diamino,bisPEG (M(w) = 1346); and monocarboxy,tetraamino,tetraPEG (M(w) = 3999). These products had NH(2) or both NH(2) and COOH terminal groups and the identity was verified by amino group analysis and ESI-TOF mass spectroscopy. Purity was determined by HPLC. Representative structures were not toxic towards an endothelial-like cell line (ECV304) at concentrations up to 4 mg/mL (over 72 h). At 37 degrees C, all of the OG-labeled PEG dendrons showed progressive uptake by ECV304 cells, but tetraamino,tetraPEG showed the greatest rate of internalization over the first 20 min. Cellular uptake was inhibited at 4 degrees C, and PEG dendron localization to perinuclear vesicles was confirmed by fluorescence microscopy. These well-defined novel architectures have potential for further development as targetable drug delivery systems or tools for construction of structurally defined modified surfaces.

SP-A binds alpha1-antitrypsin in vitro and reduces the association rate constant for neutrophil elastase.

BACKGROUND: Alpha1-antitrypsin and surfactant protein-A (SP-A) are major lung defense proteins. With the hypothesis that SP-A could bind alpha1-antitrypsin, we designed a series of in vitro experiments aimed at investigating the nature and consequences of such an interaction. METHODS AND RESULTS: At an alpha1-antitrypsin:SP-A molar ratio of 1:1, the interaction resulted in a calcium-dependent decrease of 84.6% in the association rate constant of alpha1-antitrypsin for neutrophil elastase. The findings were similar when SP-A was coupled with the Z variant of alpha1-antitrypsin. The carbohydrate recognition domain of SP-A appeared to be a major determinant of the interaction, by recognizing alpha1-antitrypsin carbohydrate chains. However, binding of SP-A carbohydrate chains to the alpha1-antitrypsin amino acid backbone and interaction between carbohydrates of both proteins are also possible. Gel filtration chromatography and turnover per inactivation experiments indicated that one part of SP-A binds several molar parts of alpha1-antitrypsin. CONCLUSION: We conclude that the binding of SP-A to alpha1-antitrypsin results in a decrease of the inhibition of neutrophil elastase. This interaction could have potential implications in the physiologic regulation of alpha1-antitrypsin activity, in the pathogenesis of pulmonary emphysema, and in the defense against infectious agents.

Photochemistry and phototoxicity of fluocinolone 16,17-acetonide.

Fluocinolone 16,17-acetonide is a corticosteroid used topically to treat various inflammatory skin diseases. Its photoreactivity was studied under UV-A and UV-B light in aqueous buffer in the presence of oxygen. This drug is photolabile under UV-B light and, to a lesser extent, under UV-A light, which is absorbed far less. In phosphate buffer, approximately 80% of fluocinolone acetonide decomposes after 5 J/cm2 of UV-B irradiation, whereas under 30 J/cm2 of UV-A light approximately only 20% decomposes. Both the drug and its photoproducts have been evaluated through a battery of in vitro studies and found to cause photohemolysis and induce photodamage to proteins (erythrocyte ghosts, bovine serum albumin) and linoleic acid. In addition, one of the photoproducts (the 17-hydroperoxy derivative) is highly toxic in the dark. Therefore, both loss of therapeutic activity and light-induced adverse effects may be expected when patients expose themselves to sunlight after drug administration. A major mechanism for phototoxicity involves radicals forming from drug breakdown, at least under UV-B, although reactive oxygen species may play a role, particularly under UV-A.