Generalized oscillator strength for Na 3s-3p transition

Generalized oscillator strengths (GOS's) for the Na $3s -3p$ transition have been investigated using the spin-polarized technique of the random phase approximation with exchange (RPAE) and the first Born approximation (FBA), focussing our attention on the position of the minimum. Intershell correlations are found to influence the position of the minimum significantly, but hardly that of the maximum. The RPAE calculation predicts for the first time the positions of the minimum and maximum at momentum transfer, $K$ values of 1.258 a.u. and 1.61 a.u., respectively. The former value is within the range of values extracted from experimental measurements, $K=1.0-1.67$ a.u.. We recommend careful experimental search for the minimum around the predicted value for confirmation.Comment: 11 pages, 2figure

Silver diagnosis in neuropathology: principles, practice and revised interpretation

Silver-staining methods are helpful for histological identification of pathological deposits. In spite of some ambiguities regarding their mechanism and interpretation, they are widely used for histopathological diagnosis. In this review, four major silver-staining methods, modified Bielschowsky, Bodian, Gallyas (GAL) and Campbell–Switzer (CS) methods, are outlined with respect to their principles, basic protocols and interpretations, thereby providing neuropathologists, technicians and neuroscientists with a common basis for comparing findings and identifying the issues that still need to be clarified. Some consider “argyrophilia” to be a homogeneous phenomenon irrespective of the lesion and the method. Thus, they seek to explain the differences among the methods by pointing to their different sensitivities in detecting lesions (quantitative difference). Comparative studies, however, have demonstrated that argyrophilia is heterogeneous and dependent not only on the method but also on the lesion (qualitative difference). Each staining method has its own lesion-dependent specificity and, within this specificity, its own sensitivity. This “method- and lesion-dependent” nature of argyrophilia enables operational sorting of disease-specific lesions based on their silver-staining profiles, which may potentially represent some disease-specific aspects. Furthermore, comparisons between immunohistochemical and biochemical data have revealed an empirical correlation between GAL+/CS-deposits and 4-repeat (4R) tau (corticobasal degeneration, progressive supranuclear palsy and argyrophilic grains) and its complementary reversal between GAL-/CS+deposits and 3-repeat (3R) tau (Pick bodies). Deposits containing both 3R and 4R tau (neurofibrillary tangles of Alzheimer type) are GAL+/CS+. Although no molecular explanations, other than these empiric correlations, are currently available, these distinctive features, especially when combined with immunohistochemistry, are useful because silver-staining methods and immunoreactions are complementary to each other

Longevity in mice: is stress resistance a common factor?

A positive relationship between stress resistance and longevity has been reported in a multitude of studies in organisms ranging from yeast to mice. Several mouse lines have been discovered or developed that exhibit extended longevities when compared with normal, wild-type mice of the same genetic background. These long-living lines include the Ames dwarf, Snell dwarf, growth hormone receptor knockout (Laron dwarf), IGF-1 receptor heterozygote, Little, α-MUPA knockout, p66shc knockout, FIRKO, mClk-1 heterozygote, thioredoxin transgenic, and most recently the Klotho transgenic mouse. These mice are described in terms of the reported extended lifespans and studies involving resistance to stress. In addition, caloric restriction (CR) and stress resistance are briefly addressed for comparison with genetically altered mice. Although many of the long-living mice have GH/IGF-1/insulin signaling-related alterations and enhanced stress resistance, there are some that exhibit life extension without an obvious link to this hormone pathway. Resistance to oxidative stress is by far the most common system studied in long-living mice, but there is evidence of enhancement of resistance in other systems as well. The differences in stress resistance between long-living mutant and normal mice result from complex interrelationships among pathways that appear to coordinate signals of growth and metabolism, and subsequently result in differences in lifespan