The hyperbranched poly(ethyl methacrylate)s (PEMAs) were prepared by the quasi‐living radical polymerization of 2‐(N,N‐diethylaminodithiocarbamoyl)ethyl methacrylate (DTCM). DTCM monomer plays an important role in this polymerization system as an inimer that is capable of initiating quasi‐living radical polymerization of the vinyl group. Hyperbranched PEMAs with relatively narrow polydispersity ( M w/ M n ≈ 1.6) were obtained. The compact nature of the hyperbranched PEMAs is demonstrated by solution properties which are different from those of the linear analogues.© 2002 Society of Chemical Industry

The generation of fluorescence and 3-deoxyglucosone (3DG), browning, polymerization, and impairment of the amino acid residues of lysozyme incubated with glucose were investigated at 37 degrees C and 50 degrees C at pH 7.4 in a phosphate or TAPSO buffer under aerobic and non-aerobic conditions with or without DETAPAC as a chelating reagent. Browning, the generation of fluorescence, and polymerization were accelerated under the non-aerobic, compared to aerobic, conditions. Moreover, the formation of 3DG was also significantly increased under non-aerobic conditions. The incubation of both reaction systems resulted in noticeable losses of arginine and lysine residues. DETAPAC significantly inhibited the advanced Maillard reaction under both aerobic and non-aerobic conditions. However, DETAPAC had no effect on the impairment of lysine and arginine residues. The generation of fluorescence, browning and polymerization of lysozyme in the TAPSO buffer were markedly inhibited under both aerobic and non-aerobic conditions. These observations suggest that transition metals in the phosphate buffer may have accelerated the formation of Amadori compounds via Schiff's base. In addition, under non-aerobic conditions, the formation of advanced glycation end products from 3DG via Amadori compounds is presumed to be the major pathway, because the formation of N epsilon-(carboxymethyl)lysine, glyoxal, and glucosone was accelerated by an oxidative reaction catalyzed with transition metal ions. These presumptions are supported by the results from a lysozyme-3DG reaction system.

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Copolymerizations of (N,N-diethyldithiocarbamyl)methylstyrene (inimer: DTCS) with maleimide (MI) were carried out under UV irradiation. DTCS monomers play an important role in this copolymerization system as an inimer that is capable of initiating radical polymerization of the vinyl group. Reactivity ratios (r 1 = 0.15 and r 2 = 0) were estimated by the curve-fitting procedure (DTCS [M 1 ]; MI[M 2 ]). These reactivities show strong alternation, and the propagating copolymer radicals proceed with homopolymerization of 1:1 complexes formed between the donor and acceptor monomers. These alternating copolymers exhibit highly branched structure and are actually hyperbranched copolymers. The compact nature of the hyperbranched molecules was demonstrated by comparison of their dilutesolution properties with those of the linear analogues. The hyperbranched macromolecules behave as single, well-separated molecules (even in good solvent) and as hard spheres.

Abstract. N, N-diethyl-m-toluamide (DEET) is a common and fairly safe active ingredient in many insect repellents. Our recent studies showed that when applied to the skin, DEET has a potent anti-parasitic effect against Schistosoma mansoni. However, the beneficial effects of DEET lasted only for a few minutes, presumably due to its rapid absorption through the skin. In this study, we evaluated different carrier formulations that prolong the activity of DEET in the skin. Among the various formulations analyzed, DEET incorporated into liposomes (LIPODEET) appeared to prolong the activity of DEET for more than 48 hr after a single application. Furthermore, LIPODEET was found to be minimally absorbed through the skin and loss due to washing off was limited. These findings thus suggest LIPODEET is a safe and long-acting formulation of DEET that is quite effective against schistosomiasis. N, N-diethyl-m-toluamide (DEET) is a relative safe, broad spectrum insect repellent that is used extensively against both human and animal pests worldwide.1,2 Although chemical research has produced a number of DEET analogs and other related compounds, none have consistently enjoyed as widespread use as DEET. 3 Even though DEET is highly effective, the duration of action of DEET appears to be short lived. Once applied to the skin, DEET has an insect repellent activity ranging from 30 min to 6 hr, 4,5 whereas its antiparasitic effect is even shorter.6 To obtain a longer duration of activity, there is a need to reapply DEET, often repeatedly with concentrations as high as 70%. 5 This is due to the fact that DEET is absorbed through the skin relatively quickly and is thus rapidly cleared from the skin.7,8 Therefore, any agent that retards the absorption of DEET through the skin will potentially prolong the repellency, or in this case the anti-parasitic action of DEET in the superficial layers of the skin. Furthermore, a reduced absorption will potentially decrease any systemic toxicity associated with DEET. We therefore tested various formulations that prolonged the effect of DEET against schistosomiasis in the skin. MATERIALS AND METHODSRadio-labeling of snails and collection of radiolabeled cercariae. Biomphalaria glabrata species of snails infected with S. mansoni were obtained from Dr. Fred Lewis (Biomedical Research Institute, Rockville, MD). The infected snails were maintained under controlled conditions of light at 85-87ЊF. Snails were checked individually for the presence of the parasite by observing the emergence of cercariae from them by exposing to a bright light source for 1 hr. Once determining that the snails are releasing cercariae, they were radiolabeled with 35 S-methionine as described previously. 9 Snails suspended in distilled water (0. 5 ml/snail) were exposed to 35 S-methionine (Tran 35 S-label, specific activity ϭ 1,047 Ci/mmol, catalog # 51006; ICN Pharmaceuticals, Inc., Irvine, CA) at a concentration of 20 Ci/ml at 37ЊC in the dark. After 16 hr of exposure to the radioisotope, the snails were rinsed, moved to ...