Mitochondria‐Targeting Polyamine–Protoporphyrin Conjugates for Photodynamic Therapy

Two polyamine derivatives of protoporphyrin IX (PPIX) were tested as photodynamic therapy (PDT) agents in HT29 colorectal cancer and HEP3B liver cancer cell lines. These compounds exhibit excellent singlet oxygen quantum yields and show strong in vitro PDT efficacy after 660 nm laser irradiation, whereas exogenous PPIX itself exhibits much weaker PDT effects. Confocal microscopy imaging studies reveal that a protoporphyrin derivative with eight amine moieties has excellent water solubility, and localizes mainly in the mitochondria of both HT29 and HEP3B cells, whereas the cellular distribution of a protoporphyrin derivative with four amine moieties is not as specific. This work demonstrates that polyamine moieties on macrocycles can enhance PDT efficacy by targeting mitochondria.     

An ecological approach to landscape planning using geographic information system technology

This paper describes two research programs that are aimed at developing ecologically-based landscape planning models. The first of these models was developed as part of a more comprehensive landscape planning research program at the University of Massachusetts. The second is an on-going program in forest land planning at the University of Vermont. In addition to an emphasis on ecological values, both projects make extensive use of computerized geographic information systems (GIS) for data storage, analysis and display. The emphasis has been to develop a synthesis of planning procedures, ecological theories and quantitative techniques. Both research efforts were guided by a three-part methodological framework adapted from the work of Eugene Odum. The Massachusetts work generated a two-part classification system. The first part of the classification uses the statistical technique of discriminant analysis to place land uses into five groups, each having similar ecological characteristics. The second part of the classification is based on the physical and environmental characteristics of a site. The biological and denudational potentials of a site are determined from soil characteristics and slope. A comparison of the two classification schemes was made to determine ecological compatibility. The procedures were applied to two communities in Western Massachusetts. The Vermont study was aimed at integrating ecological values into forest land management and planning processes. The research utilized soils and topographic information in the development of an ecologically based forest land suitability model. Forest site index and soil erosion potential were determined using data stored in a computerized geographic information system. Forest site index estimates were made by utilizing an existing, well documented soil-site index regression equation applicable to the Green Mountains of Vermont. Soil erosion potential estimates were made by combining a soil erodability factor (K) with slope. The site index and soil erosion estimates were combined to produce land suitability classes for resource protection, forest management, multiple-use and trade-off. The procedure was applied in the Mad River Valley in Central Vermont. Both the Massachusetts and the Vermont studies are seen as significant contributions toward the integration of ecological factors into processes for landscape planning and resource management.     

The superiority of Ti plate as the substrate of dye-sensitized solar cells

The photovoltaic properties of dye-sensitized solar cells (DSCs) based on several types of substrates, FTO, Ti and stainless steel, were investigated. The sheet resistances of the substrates were correlated to the photovoltaic properties. The efficiency of the DSC using Ti substrate was higher than that of the DSCs using stainless steel and FTO. For the large-size DSCs based on FTO, the metal track is an important component to retain the decrease in cell performance due to the relatively high sheet resistance of FTO. To minimize the internal resistance of DSCs, the Ti sheet was used as a support of nano-crystalline TiO₂ due to the low sheet resistance. Although the IPCE of DSCs based on Ti substrate was lower than that of DSCs based on FTO in the range from 400 to 500 nm, the DSC based on Ti substrate showed the higher IPCE in red region due to the light reflecting on Ti substrate. The efficiency of 3.2% for the DSC based on Ti substrate was obtained with a Jsc , Voc 0.75 V, and FF 0.610. This result shows that the Ti plate has superiority for producing the large DSCs without metal track and reduces the cost of DSCs.     

Evaluation of soft error rates using nuclear probes in bulk and SOI SRAMs with a technology node of 90 nm

The difference of soft error rates (SERs) in conventional bulk Si and silicon-on-insulator (SOI) static random access memories (SRAMs) with a technology node of 90 nm has been investigated by helium ion probes with energies ranging from 0.8 to 6.0 MeV and a dose of 75 ions/μm². The SERs in the SOI SRAM were also investigated by oxygen ion probes with energies ranging from 9.0 to 18.0 MeV and doses of 0.14–0.76 ions/μm². The soft error in the bulk and SOI SRAMs occurred by helium ion irradiation with energies at and above 1.95 and 2.10 MeV, respectively. The SER in the bulk SRAM saturated with ion energies at and above 2.5 MeV. The SER in the SOI SRAM became the highest by helium ion irradiation at 2.5 MeV and drastically decreased with increasing the ion energies above 2.5 MeV, in which helium ions at this energy range generated the maximum amount of excess charge carriers in a SOI body. The soft errors occurred by helium ions were induced by a floating body effect due to generated excess charge carriers in the channel regions. The soft error occurred by oxygen ion irradiation with energies at and above 10.5 MeV in the SOI SRAM. The SER in the SOI SRAM gradually increased with energies from 10.5 to 13.5 MeV and saturated at 18 MeV, in which the amount of charge carriers induced by oxygen ions in this energy range gradually increased. The computer calculation indicated that the oxygen ions with energies above 13.0 MeV generated more excess charge carriers than the critical charge of the 90 nm node SOI SRAM with the designed over-layer thickness. The soft errors, occurred by oxygen ions with energies at and below 12.5 MeV, were induced by a floating body effect due to the generated excess charge carriers in the channel regions and those with energies at and above 13.0 MeV were induced by both the floating body effect and generated excess carriers. The difference of the threshold energy of the oxygen ions between the experiment and the computer calculation might be due to the difference between the designed and real structures.     

Variant antibody identification by peptide mapping

During development of CGP56901, a monoclonal antibody (MAb) specific for a unique epitope on human IgE, the protein A-purified IgG from one of the candidate production cell lines, showed an additional minor heavy chain (H-chain) band with a molecular weight slightly lower than that of the principal H-chain band on SDS-PAGE. The N-terminal amino acid sequence of this minor H-chain species indicated that at least the first 30 amino acids were identical to those of the antibody light-chain (L-chain) variable domain. More detailed studies using peptide mapping and amino acid sequencing analysis confirmed a crossover event between the V genes of the antibody. The position is between Arg108 of the L chain and Ala124 of the H chain. This crossover resulted in a variant H chain, which had 16 fewer amino acid residues than the normal CGP56901 H chain. These results show that peptide mapping is a useful "first-line" analytical tool in the characterization of the quality of the monoclonal antibody.     

Tetraphenylporphyrin Enters the Ring: First Example of a Complex between Highly Bulky Porphyrins and a Protein**

Tetraphenylporphyrin (TPP) is a symmetrically substituted synthetic porphyrin whose properties can be readily modified, providing it with significant advantages over naturally occurring porphyrins. Herein, we report the first example of a stable complex between a native biomolecule, the haemoprotein HasA, and TPP as well as its derivatives. The X-ray crystal structures of nine different HasA-TPP complexes were solved at high resolutions. HasA capturing TPP derivatives was also demonstrated to inhibit growth of the opportunistic pathogen Pseudomonas aeruginosa. Mutant variants of HasA binding FeTPP were shown to possess a different mode of coordination, permitting the cyclopropanation of styrene.