Pore morphologies and diffusion within hydrated polyelectrolyte membranes: homogeneous vs heterogeneous and random side chain attachment.

Using dissipative particle dynamics pore morphologies within model ionomer membranes are simulated. The ionomers are composed of hydrophobic backbones and side chains that are end-linked with a hydrophilic acid containing site. The separation distance between successive branching points is bi-modal, being alternating short (distance x) and long (distance y). The dependence of morphology on ion exchange capacity and separation distance is investigated. Phase separated morphologies were calculated at a water content of 16 vol. %. An increase of side chain density results in a decreasing size of the water containing pores, distance between them and decreasing Bragg spacing. For fixed side chain density, an increase in difference between the longer and shorter separation distance (y - x) results in a larger Bragg spacing. Monte Carlo calculations demonstrate that a large majority of the water is contained within a percolating network that allows for long-range diffusion. Diffusion constants vary drastically with architecture: Diffusion is fastest for architectures for which the side chains are highly non-uniformly distributed (y ≫ x). For architectures with the same side chain density, the tracer diffusion constants increase linearly with increase of the asymmetry ratio y∕x (y > x). This is caused by the cooperative action of those terminal acidic sites that are topologically close together, allowing them to arrange pair wise along the pore walls and make the pores larger. We verified that for polymer architectures that mimick Nafion1200 similar trends are obtained, resulting in increased H(2)O, O(2), and H(2) permeation for statistical side chain distribution as compared to a uniform distribution of side chains. This trend is most pronounced for H(2)O and less pronounced for H(2).

[Surgical fixation for flail chest].

Flail chest occurs by blunt chest trauma and is associated with pulmonary contusion, atelectasis, pneumothorax, hemothorax, and respiratory failure. Because of its severity, it may need internal pneumatic stabilization or surgical fixation. Some patients do not need the internal stabilization and are observed conservatively. Some of these patients, however, increase the flail after palliating the pain and getting up. These patients show inefficient ventilation and surgical fixation is needed. The operation should be performed after the improvement of pulmonary contusion. In this paper, we presented 2 patients who showed such course and clarified the surgical methodology.

Estrogenic activity of 37 components of commercial sunscreen lotions evaluated by in vitro assays.

Thirty-seven chemical components of commercial sunscreen lotions were evaluated for estrogen agonistic and/or antagonistic activity using two in vitro assays, (1) an ELISA-based estrogen receptor competitive binding assay (ER-ELISA) and (2) a modified yeast two-hybrid estrogen assay, with and without addition of a rat liver preparation, S9 mix. Eleven compounds, most of which were benzophenone derivatives and parabens, showed binding affinity to ER by ER-ELISA without S9 mix. Although the activities of almost all of the compounds were attenuated by addition of S9 mix, 4-octylphenylsalicylate and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone acquired estrogenic activity, suggesting metabolic activation of these compounds. Two benzophenones showed agonistic activity in the yeast two-hybrid assay without S9 mix. The activity of one of these was reduced by S9 treatment and a further two benzophenones was activated. Eight parabens were active in this assay without S9 exposure, but their activities were eliminated by S9 treatment. Benzophenones with para-phenolic hydroxyl groups and parabens with branched and/or longer linear chains were generally more potent in both bioassays. In addition, weak antagonistic activity of 4-t-butylphenyl-salicylate, 2-ethylhexyl 4-dimethylaminobenzoate and (+/-)-alpha-tocopherolacetate was observed with S9 treatment. In vivo testing of the compounds reported here to have estrogen agonistic and antagonistic activities is required to confirm their effects at an organismal level.

Oligonucleotide synthesis using the 2-(levulinyloxymethyl)-5-nitrobenzoyl group for the 5'-position of nucleoside 3'-phosphoramidite derivatives.

A comparative study on the utility of 2-(levulinyloxymethyl)-5-nitrobenzoyl (LMNBz) and 2-(levulinyloxymethyl)benzoyl (LMBz) protecting groups for the 5'-positions of nucleoside 3'-phosphoramidite derivatives in the oligonucleotide synthesis is presented in terms of the syntheses of TpTpT, TpTpTpT, and UpCpApGpUpUpGpG. In addition we describe the synthesis, using the LMNBz protecting group, of the CpCpA terminus triplet of tRNAs bearing exocyclic amino groups with 15N-labeling, and the trimer Gp[A*]pG containing 2'-O-(beta-D-ribofuranosyl)adenosine ([A*]), the latter of which is found at position 64 in the yeast initiator tRNA(Met).

Oligonucleotide synthesis by the use of a 2-(levulinyloxymethyl)-5-nitrobenzoyl (LMNBZ) group for the 5'-hydroxyl group of ribonucleoside and 2'-deoxyribonucleoside 3'-phosphoramidites.

Synthetic studies on the CpCpA terminus triplet, whose exocyclic amino groups are all labeled with 15N, and a phosphorodithioate-linked oligonucleotide in terms of 2-(levulinyloxymethyl)-5-nitrobenzoyl (LMNBz) group as the novel base-labile protecting group for the 5'-hydroxyl groups of nucleoside 3'-phosphoramidites, are described.