Periodontitis induced by bacterial infection exacerbates features of Alzheimer\u27s disease in transgenic mice.

Periodontitis is a localized infectious disease caused by periodontopathic bacteria,such as Porphyromonas gingivalis. Recently, it has been suggested that bacterial infections may contribute to the onset and the progression of Alzheimer’s disease (AD). However, we do not have any evidence about a causative relationship between periodontitis and AD. In this study, we investigated by using a transgenic mouse model of AD whether periodontitis evoked by P. gingivalis modulates the pathological features of AD. Cognitive function was significantly impaired in periodontitis-induced APP-Tg mice, compared to that in control APP-Tg mice. Levels of Amiloid β (Aβ) deposition, Aβ40, and Aβ42 in both the hippocampus and cortex were higher in inoculated APP-Tg mice than in control APP-Tg mice. Furthermore, levels of IL-1β and TNF-α in the brain were higher in inoculated mice than in control mice. The levels of LPS were increased in the serum and brain of P. gingivalis-inoculated mice. P. gingivalis LPS-induced production of Aβ40 and Aβ42 in neural cell cultures and strongly enhanced TNF-α and IL-1β production in a culture of microglial cells primed with Aβ. Periodontitis evoked by P. gingivalismay exacerbate brain Aβ deposition, leading to enhanced cognitive impairments, by a mechanism that involves triggering brain inflammation

Frustration and single crystal morphology of isotactic poly(2-vinylpyridine)

The crystal structure of isotactic poly(2-vinylpyridine) (iP2VP) established in 1977 by Puterman et al. is shown to conform to a recently proposed frustrated packing scheme which involves three isochiral three-fold helices packed in a trigonal unit-cell, and observed in a number of polymers and biopolymers. Single crystals of iP2VP grown from thin films at high temperature (Tc approximate to 200 degrees C) display highly unusual morphologies with six (100) growth sectors but a three-fold overall symmetry apparent through different lamellar thicknesses in adjacent growth sectors, and oblique growth facets of three of the sectors. These features are morphological manifestations of the frustration of the helix packing, and support the P3(1) or P3(2) space group of the unit-cell. The different lamellar thicknesses are mainly due to an isothermal thickening process, which has different impacts depending on the nature of the growth faces. Analysis of the growth features of frustrated structures can be of help when dealing with finer details of theories of polymer crystal growth. (C) 1998 Elsevier Science Ltd. All rights reserved