Effect of alpha-tocopherol on pulmonary antioxidant defence system and lipid peroxidation in cigarette smoke inhaling mice

Background  

Free radicals generated in biological systems by cigarette smoke (CS) inhalation can cause oxidative stress in tissues, resulting in lipid peroxidation (LPO). In view of the antioxidant properties of α-tocopherol (AT), in the present study, effects of AT on antioxidant defence system and LPO were investigated in mice inhaling CS for different time intervals.     

Application of complex macromolecular architectures for advanced microelectronic materials

The distinctive features of well-defined, three-dimensional macromolecules with topologies designed to enhance solubility and amplify end-group functionality facilitated nanophase morphologies in mixtures with organosilicates and ultimately nanoporous organosilicate networks. Novel macromolecular architectures including dendritic and star-shaped polymers and organic nanoparticles were prepared by a modular approach from several libraries of building blocks including various generations of dendritic initiators and dendrons, selectively placed to amplify functionality and/or arm number, coupled with living polymerization techniques. Mixtures of an organosilicate and the macromolecular template were deposited, cured, and the phase separation of the organic component, organized the vitrifying organosilicate into nanostructures. Removal of the sacrificial macromolecular template, also denoted as porogen, by thermolysis, yielded the desired nanoporous organosilicate, and the size scale of phase separation was strongly dependent on the chain topology. These materials were designed for use as interlayer, ultra-low dielectric insulators for on-chip applications with dielectric constant values as low as 1.5. The porogen design, chemistry and role of polymer architecture on hybrid and pore morphology will be emphasized.     

Direct supercritical fluid extraction of nitrogenous bases from aqueous solution

The feasibility of using supercritical carbon dioxide for both static and dynamic extraction of organic bases from an aqueous matrix has been investigated. It appears that the greater the lipophilic portion of the molecule the more readily is the base extracted: triprolidine, sulfamethazine and caffeine were extracted whereas picolinic acid, succinonitrile, and nicotine were not.     

Parallel synthesis and evaluation of 132 (+)-1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CBI) analogues of CC-1065 and the duocarmycins defining the contribution of the DNA-binding domain

The solution-phase, parallel synthesis and evaluation of a library of 132 (+)-1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CBI) analogues of CC-1065 and the duocarmycins containing dimeric monocyclic, bicyclic, and tricyclic heteroaromatic replacements for the DNA-binding domain are described. This systematic study revealed clear trends in the structural requirements for observation of potent cytotoxic activity and DNA alkylation efficiency, the range of which spans a magnitude of > or =10 000-fold. Combined with related studies, these results highlight that the role of the DNA-binding domain goes beyond simply providing DNA-binding selectivity and affinity (10-100-fold enhancement in properties), consistent with the proposal that it contributes significantly to catalysis of the DNA alkylation reaction accounting for as much as an additional 1000-fold enhancement in properties.     

Critical petermann K factor for intensity noise squeezing

We investigate the impact of the Petermann-excess-noise factor K>/=1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest Petermann factor significantly impedes squeezing, which becomes impossible when K>/=1.5. This appears as a serious limitation for obtaining sub-shot-noise light from practical semiconductor lasers. We present experimental evidence for our theory.     

Thermoresponsive Random Poly(ether urethanes) with Tailorable LCSTs for Anticancer Drug Delivery

A new class of thermoresponsive random polyurethanes is successfully synthesized and characterized. Poly(ethylene glycol) diol (M_n = 1500 Da) and 2,2‐dimethylolpropionic acid are reacted with isophorone diisocyanate in the presence of methane sulfonic acid catalyst. It is found that these polyurethanes are thermoresponsive in aqueous media and manifest a lower critical solution temperature (LCST) that can be easily tuned from 30 °C to 70 °C by increasing the poly(ethylene glycol) content. Their sharp LCST transitions make these random polyurethanes ideal candidates for stimuli‐responsive drug delivery applications. To that end, the ability of these systems to efficiently sequester doxorubicin (up to 36 wt%) by means of a sonication/dialysis method is successfully demonstrated. Additionally, it is also demonstrated that accelerated doxorubicin release kinetics from the nanoparticles can be attained above the LCST.

     

Sn(OTf)2 and Sc(OTf)3: Efficient and versatile catalysts for the controlled polymerization of lactones

A general and novel method for the controlled synthesis of aliphatic polyesters is presented. The evaluation of stannous (II) trifluoromethane sulfonate [Sn(OTf)₂] and scandium (III) trifluoromethane sulfonate [Sc(OTf)₃] as catalysts for the ring‐opening polymerization (ROP) of various lactones is described as a route to polyesters under mild and highly selective polymerization conditions. Size exclusion chromatograms of poly(ϵ‐caprolactone) initiated from ethanol in the presence of either Sn(OTf)₂ or Sc(OTf)₃ demonstrate the facile synthesis of narrowly dispersed products. Predictable molecular weights, typical of a living or controlled polymerization, were obtained with high yields. These catalysts are versatile and applicable toward the ROP of other cyclic (di)esters, including β‐butyrolactone, which produces the synthetic analogue of the biopolymer poly(β‐hydroxybutyrate). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2067–2074, 2000