Pentapeptide (pepstatin) inhibition of brain acid proteinase

The pentapeptide pepstatin obtained from culture filtrates of actinomycetes completely inhibited brain acid proteinase (cathepsin D) at exceedingly low concentrations. Among the brain enzymes tested, the effect is specific for acid proteinase because addition of 1000-fold higher concentrations was without effect on neutral proteinase, aminopeptidase, and arylamidases. Pepstatin also inhibits pepsin as tested with hemoglobin or with N-acetylphenylalanyl-L-diiodotyrosine as substrate. Pepstatin must be regarded as the most powerful agent yet described that inhibits intracellular acidic proteolytic enzyme in brain.     

A Dwarf Mutant of Arabidopsis Generated by T-DNA Insertion Mutagenesis

Most plant genes that control complex traits of tissues, organs, and whole plants are uncharacterized. Plant height, structure of reproductive organs, seed development and germination, for example, are traits of great agronomic importance. However, in the absence of knowledge of the gene products, current molecular approaches to isolate these important genes are limited. Infection of germinatng seeds of Arabidopsis thaliana with Agrobacterium results in transformed lines in which the integrated T-DNA from Agrobacterium and its associated kanamycin-resistance trait cosegregate with stable, phenotypic alterations. A survey of 136 transformed lines produced plants segregating in a manner consistent with Mendelian predictions for phenotypes altered in height, flower structure, trichomes, gametogenesis, embryogenesis, and seedling development. This report is the characterization of a dwarf mutant in which the phenotype is inherited as a single recessive nuclear mutation that cosegregates with both the kanamycin-resistance trait and the T-DNA insert.     

Visual pigment density in single primate foveal cones

The feasibility is demonstrated of microspectrophotometric studies on primate photoreceptors aligned at right angles to the test beam, rather than axially illuminated. Pigment densities, and hence absorption per unit thickness, are approximately equal in primate rods and foveal cones. These pigment densities are similar to those reported for frog rods and fish cones.     

Actinide organometallic chemistry

The stoichiometric and catalytic chemistry of metal-organic compounds having actinide-to-carbon bonds is in a stage of rapid growth. Chemical, structural, and bonding characteristics have been identified which differ in interesting and informative ways from those of d-block transition element compounds.     

Seasat visible and infrared radiometer

Visual and infrared images produced by the Seasat visible and infrared radiometer (VIRR) are adequate for the identification of cloud, land, and water features. A statistical comparison of VIRR-derived sea-surface temperatures in a cloud-free region with a National Oceanic and Atmospheric Administration analysis based on various surface measurements taken in the same region showed agreement to +/- 1.7 degrees K root-mean-square.     

Breast and ovarian cancer risks due to inherited mutations in BRCA1 and BRCA2

Risks of breast and ovarian cancer were determined for Ashkenazi Jewish women with inherited mutations in the tumor suppressor genes BRCA1 and BRCA2. We selected 1008 index cases, regardless of family history of cancer, and carried out molecular analysis across entire families. The lifetime risk of breast cancer among female mutation carriers was 82%, similar to risks in families with many cases. Risks appear to be increasing with time: Breast cancer risk by age 50 among mutation carriers born before 1940 was 24%, but among those born after 1940 it was 67%. Lifetime risks of ovarian cancer were 54% for BRCA1 and 23% for BRCA2 mutation carriers. Physical exercise and lack of obesity in adolescence were associated with significantly delayed breast cancer onset.     

Polymer gate dielectric surface viscoelasticity modulates pentacene transistor performance

Nanoscopically confined polymer films are known to exhibit substantially depressed glass transition temperatures (Lg's) as compared to the corresponding bulk materials. We report here that pentacene thin films grown on polymer gate dielectrics at temperatures well below their bulk Tg's exhibit distinctive and abrupt morphological and microstructural transitions and thin-film transistor (TFT) performance discontinuities at well-defined growth temperatures. The changes reflect the higher chain mobility of the dielectric in its rubbery state and are independent of dielectric film thickness. Optimization of organic TFT performance must recognize this fundamental buried interface viscoelasticity effect, which is detectable in the current-voltage response.