Six match-to-sample picture/object selection experiments were designed to explore children's knowledge about superordinate words (e.g., "food") and how they acquire this knowledge. Three factors were found to influence the learning and extension of superordinate words in 3- to 5-year-old children (N = 230): The number of standards (one versus two), the type of standards presented (from different basic-level categories versus from the same basic-level category), and the nature of the object representations used (pictures versus objects).
The yeast Sir2 protein mediates chromatin silencing through an intrinsic NAD-dependent histone deacetylase activity. Sir2 is a conserved protein and was recently shown to regulate lifespan extension both in budding yeast and worms. Here, we show that SIRT1, the human Sir2 homolog, is recruited to the promyelocytic leukemia protein (PML) nuclear bodies of mammalian cells upon overexpression of either PML or oncogenic Ras (Ha-rasV12). SIRT1 binds and deacetylates p53, a component of PML nuclear bodies, and it can repress p53-mediated transactivation.
Molecular advances of the past decade have led to the discovery of a myriad of 'aging genes' (methuselah, Indy, InR, Chico, superoxide dismutase) that extend Drosophila lifespan by up to 85%. Despite this life extension, these mutants are no longer lived than at least some recently wild-caught strains. Typically, long-lived mutants are identified in relatively short-lived genetic backgrounds, and their effects are rarely tested in genetic backgrounds other than the one in which they were isolated or derived.
Telomere shortening in normal human cells causes replicative senescence, a p53-dependent growth arrest state, which is thought to represent an innate defence against tumour progression. However, although it has been postulated that critical telomere loss generates a 'DNA damage' signal, the signalling pathway(s) that alerts cells to short dysfunctional telomeres remains only partially defined.
Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
OBJECTIVE: To estimate the processing time and neuromuscular delay required to extract and process sensory information from the ankle in order to coordinate an upper extremity movement sequence. METHODS: Nineteen able-bodied subjects were tested on their ability to perform a motor task that involved extension of their left index finger when their left ankle was passively plantar flexed at random velocities through a predetermined target angle. RESULTS: We found that the able-bodied subjects were able to adjust their finger responses up to ankle velocities of 70 degrees /s (300 ms).
Many degenerative diseases that occur with aging, as well as premature aging syndromes, are characterized by presenting cells with critically short telomeres. Telomerase reintroduction is envisioned as a putative therapy for diseases characterized by telomere exhaustion. K5-mTert transgenic mice overexpress telomerase in a wide spectrum of tissues. These mice have a higher incidence of both induced and spontaneous tumors, resulting in increased mortality during the first year of life.
Proceedings of the National Academy of Sciences of the United States of America
In investigating the role of metal ions in the pathogenesis of Huntington's disease, we examined the effects of clioquinol, a metal-binding compound currently in clinical trials for Alzheimer's disease treatment, on mutant huntingtin-expressing cells. We found that PC12 cells expressing polyglutamine-expanded huntingtin exon 1 accumulated less mutant protein and showed decreased cell death when treated with clioquinol. This effect was polyglutamine-length-specific and did not alter mRNA levels or protein degradation rates.
International Journal of Radiation Oncology, Biology, Physics
PURPOSE: We investigated the effects of fractionated radiation treatments on the life spans of athymic rats bearing intracerebral brain tumors. METHODS AND MATERIALS: U-251 MG or U-87 MG human glioblastoma cells were implanted into the brains of athymic rats, and the resulting tumors were irradiated once daily with various doses of ionizing radiation for 5 consecutive days or for 10 days with a 2-day break after Day 5. RESULTS: Five daily doses of 1 and 1.5 Gy, and 10 doses of 0.75 and 1 Gy, cured some U-251 MG tumors.
A comparison of the data published in anatomy textbooks and anthropological tables does not reveal any change in basic heart dimensions during the period since the beginning of the 20th century to nowadays. However, normal values of many other parameters have changed up to 30% over the same period. These changes may be caused by the acceleration phenomenon or the extension of average lifespan.