Non-fibrillar amyloid-β peptide reduces NMDA-induced neurotoxicity, but not AMPA-induced neurotoxicity

Amyloid-β peptide (Aβ) is thought to be linked to the pathogenesis of Alzheimer’s disease. Recent studies suggest that Aβ has important physiological roles in addition to its pathological roles. We recently demonstrated that Aβ42 protects hippocampal neurons from glutamate-induced neurotoxicity, but the relationship between Aβ42 assemblies and their neuroprotective effects remains largely unknown. In this study, we prepared non-fibrillar and fibrillar Aβ42 based on the results of the thioflavin T assay, Western blot analysis, and atomic force microscopy, and examined the effects of non-fibrillar and fibrillar Aβ42 on glutamate-induced neurotoxicity. Non-fibrillar Aβ42, but not fibrillar Aβ42, protected hippocampal neurons from glutamate-induced neurotoxicity. Furthermore, non-fibrillar Aβ42 decreased both neurotoxicity and increases in the intracellular Ca²⁺ concentration induced by N-methyl-d-aspartate (NMDA), but not by α-amino-3-hydrozy-5-methyl-4-isoxazole propionic acid (AMPA). Our results suggest that non-fibrillar Aβ42 protects hippocampal neurons from glutamate-induced neurotoxicity through regulation of the NMDA receptor.     

Superoxide dismutases: a physiopharmacological update

Reactive oxygen species (ROS) are known participants in several cellular processes. Superoxide anion radical, one example of ROS, forms as a result of normal cellular respiration and is usually cleared successfully by superoxide dismutase (SOD) and other radical scavengers. However, when superoxide exceeds the clearance capacity of SOD and other ROS scavengers, superoxide initiates a number of pathologic processes. This review examines pathologies involving superoxide, including: cancer, neurodegenerative diseases, ischemia/reperfusion injury, and inflammation. We will also explore the basic science principles of superoxide and SOD, including: SOD evolution, SOD mutations, biochemistry, physiology, and pathophysiology. In reviewing the basic science, clinical pathology, and therapeutic research, we hope to clearly demonstrate plausible pharmacologic targets of action. We have revised data about basic science, clinical pathology and therapeutic research in an effort to propose plausible pharmacological targets of action. The understanding of these aspects is critical in the accomplishment of a successful clinical intervention.     

Dry matter production, population structure and environmental conditions of the spring ephemeralErythronium japonicum growing in various habitats differing in sunlight exposure in cool temperate Japan

Phenology, dry matter production, population structure and environmental conditions were examined inErythronium japonicum Decne plants growing on the floor of a deciduous broad-leavedQuercus mongolica forest (Q.m. stand), an evergreen coniferousCryptomeria japonica plantation (C. j. stand) and bare ground left for 3 years after the clearing of a forest composed of youngQ. mongolica andPinus densiflora trees (bare stand) in the cool temperate zone of Japan. The average population density of the plants growing at theQ.m. stand was much higher than that observed at the bare stand, whereas the average number of flowering plants at the former stand was less than half of that at the latter. The population density and number of flowering plants growing at theC. j. stand were both less than 30% of those at theQ. m. stand. The number of seedlings at theQ. m. stand was much more than that at the bare andC. j. stands. Their survivorship rate over 1 year at the former stand also seems to be significantly higher than those at the other stands. Their aboveground and belowground parts at the bare stand were exposed to more severe heat and water stress than those at the other two stands. The net production per leaf area of the plants growing at theQ. m. stand was two and six times larger than those at the bare andC. j. stands, respectively. The plants at the bare stand did not use the available solar radiation as efficiently for dry matter production through photosynthesis as those growing at theQ. m. stand, whereas those at theC. j. stand are strongly restricted in their photosynthetic process by the significantly limited light condition on the floor of the evergreen coniferous plantation. The differences in the number of plants reaching sexual maturity, the density and structure of the population and the net production between their three habitats are discussed here from the standpoint of differences in environmental conditions.