DNA‐Templated Synthesis of Perylenediimide Stacks Utilizing Abasic Sites as Binding Pockets and Reactive Sites

DNA is considered to be a promising biomolecule as a template and scaffold for arranging and organizing functional molecules on the nanoscale. The construction and evaluation of DNAs containing multiple functional molecules that are useful for optoelectronic devices and sensors has been studied. In this paper we report the efficient incorporation of perylenediimide (PDI) units into DNA by using abasic sites both as binding sites and as reactive sites and the construction of PDI stacks within the DNA structure, accomplished through the preorganization of the PDI units in the hydrophobic pocket within the DNA. Our approach could become a valuable method for construction of DNA/chromophore hybrid structures potentially useful for the design of DNA‐based devices and biosensors.     

Development of a High-Affinity Antibody-Binding Peptide for Site-Specific Modification

Immunoglobulin G (IgG)-binding peptides such as 15-IgBP are convenient tools for the site-specific modification of antibodies and the preparation of homogeneous antibody–drug conjugates. A peptide such as 15-IgBP can be selectively crosslinked to the fragment crystallizable region of human IgG in an affinity-dependent manner via the ϵ-amino group of Lys8. Previously, we found that the peptide 15-Lys8Leu has a high affinity (K_d=8.19 nM) due to the presence of the γ-dimethyl group in Leu8. The primary amino group required for the crosslinking to the antibodies has, however, been lost. Here, we report the design and synthesis of a novel unnatural amino acid, 4-(2-aminoethylcarbamoyl)leucine (Aecl), which possesses both the γ-dimethyl fragment and a primary amino group. A peptide containing Aecl8 (15-Lys8Aecl) was synthesized and showed a binding affinity ten times higher (K_d=24.3 nM) than that of 15-IgBP (K_d=267 nM). Fluorescein isothiocyanate (FITC)-labeled 15-Lys8Aecl with an N-hydroxy succinimide ester at the side chain of Aecl8 (FITC-15-Lys8Aecl(OSu)) successfully labeled an antibody (trastuzumab, Herceptin^®) with the fluorophore. This peptide scaffold has both strong binding affinity and crosslinking capability, and could be a useful tool for the selective chemical modification of antibodies with molecules of interest such as drugs.     

Room temperature CW operation ofGa0.3In0.7As/GaInAsP/InP strained MQW lasers withwire active region

A room temperature CW operation of Ga_0.3In_0.7As/GaInAsP/InP GRINSCH compressive strained MQW lasers with 30~60 nm wide wire active region was achieved. This device was fabricated by two-step LP-OMVPE growths on p-type InP substrate and wet chemical etching. Threshold current as low as 53 mA ( L=910 μm, J_th=2.9 kA/cm²) was obtained at RT-CW condition. The spontaneous emission peak and the lasing wavelength of strained MQW wire lasers exhibited approximately 20-meV blue shift from those of MQW film lasers cut out from the same wafer     

A Spin Resonance Investigation of Magnetism and Dynamics in the Charge-transfer Salts β"-(BEDT-TTF)4[(H3O)M(C2O4)3]S

We report a spin resonance study of the family of quasi-two-dimensional organic (super)conductors β”-(BEDT-TTF)₄[(H₃O)M(C₂O₄)₃]S, where M is a 3d transition metal ion and S is a host solvent molecule. The spin systems for M = Cr³⁺ (S = 3/2) and M = Fe³⁺ (S = 5/2) are investigated by means of both resonant and field modulation techniques in the frequency range between 50 and 313 GHz. The role of the different solvent molecules in determining the degree of spin-orbit coupling and the local symmetry at the metal ion site is established. The low temperature behaviour of intensities, positions and widths of the resonant lines shows significant modifications of the spin-orbit coupling, and of the inter-and intra-ionic spin-spin inter actions. Despite the onset of a weak antiferromagnetic internal field at low temperature, the ultimate narrowing of the lines suggests spin-lattice interactions may still be the dominant relaxation process. Diamagnetic screening in the mixed state of the superconducting samples for fields parallel to the quasi-two-dimensional layers induces additional lineshifts only below B = 2.5T and T = 4K, determining the threshold of full field penetration within the anion layers.     

Pharmacokinetics and metabolism of the new thromboxane A2 receptor antagonist ramatroban in animals. 2nd communication: distribution to organs and tissues in male, female and pregnant rats, and characteristics of protein binding in plasma

Developmental profiles of antioxidant enzymes and lipid peroxidation were investigated in rat cerebral hemisphere from birth to 600 days of age. Lipid peroxidation level decreased in the crude homogenate from birth until 15 days and, thereafter increased gradually up to 600 days. However, susceptibility of sub-cellular fractions to lipid peroxidation displayed an increasing trend with increasing age. Superoxide dismutase activity decreased gradually with age, whereas activities of catalase, glutathione peroxidase and glutathione reductase exhibited an elevation up to 90 days followed by either a stagnancy or diminution in the later life. No linearity was observed in the contents of glutathione, ascorbic acid and H2O2 in the tissue. The results suggest that free radicals could be the causative agents of the aging process in which antioxidant enzymes have a definite regulatory contribution.     

Culture system for extensive production of CD19+IgM+ cells by human cord blood CD34+ progenitors

We established a co-culture system with a monolayer of the murine bone marrow (BM) stroma cell line, MS-5, in which human cord blood CD34+ cells differentiated to CD19+ cells. The addition of stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) highly enhanced the production of CD19+ cells. The expansion of the cell numbers was over 10(3)-fold. Furthermore, a significant proportion (<45%) of the cells expressed surface IgM (sIgM) after 5 weeks of co-culture. CD34+CD19- cells also showed a similar development of CD19+ cells and CD19+sigM+ cells. Filter separation of MS-5 cells and CD34+ cells did not inhibit the growth of CD19+ cells. However, when further purified CD34+CD19-CD13- CD33- cells were cultured in the presence of MS-5 cells with or without a separation filter, CD19+ cells did not appear in the non-contact setting. This result suggested that the highly purified CD34+CD19-CD13-CD33- progenitors require the cell-cell contact for the development of CD19+ cells, whereas other CD34+ fractions contain progenitors that do not require the contact. This co-culture system should be useful for the study of early human B-lymphopoiesis.     

Determination of coupling coefficient of DFB lasers by a newly proposed method

A new method of estimating the coupling coefficient of DFB lasers is proposed. A sub/main-mode spectral intensity ratio below the threshold current is employed in this method, instead of the stop-bandwidth used in the conventional method. It is demonstrated both theoretically and experimentally that the new method is capable of more accurate determination of the coupling coefficient of DFB lasers with phase-shifted corrugations.     

Annotated references on neutron and photon production from thick targets bombarded by charged particles

The literature on neutron and photon production from thick targets bombarded by charged particles has been surveyed. The survey covers fourteen journals and some internal reports and conference proceedings, mainly from 1965 up to June 1984. For each paper, applicable information is listed on type and energy of the projectile, the accelerator used, composition and thickness of the target, the experimental method, the calculation, and the quantities obtained. The references on neutron and on photon production are accessed through two indices which list the available projectile-target combinations and the projectile energy range.     

High-speed 1.5 μm self-aligned constricted mesa lasers grownentirely by MOCVD

A self-aligning (SA) process technique to fabricate constricted mesa (CM) lasers is proposed. The controllability of GaInAsP active region volume and InP lateral confining layer widths were greatly improved. Lasers grown entirely by metalorganic chemical vapour deposition (MOCVD) showed very small variation in threshold currents ( I_th=15.2±1.1 mA) and in stray junction capacitances (C=1.62±0.08 pF). A record bandwidth of 10 GHz in the 1.5 μm-wavelength region was demonstrated