Developing a Model for Slow Hypoxic Injury and Vascular Degeneration in Amyloid Burdened Brains

The breakdown of neurovascular systems may play a crucial role in the pathogenesis of Alzheimer’s disease. However whether this breakdown initiates a degenerative mechanism or is the consequence of some other deleterious process remains unknown. We examined hippocampal pathology in double transgenic mice overexpressing a human mutant gene encoding the amyloid precursor protein (APPSwe/Ind) using a combination of histochemistry and stereologic techniques. Expression of APPSwe/Ind in these mice is driven by a tetracycline-sensitive promoter. Tetracycline transcriptional activator (tTA), the second transgene, is driven in turn by a CAM KIIa promoter that is only active in neurons. Thus this double transgenic construct allows us to control expression of APPSwe/Ind with doxycycline. Utilizing this characteristic, we created three distinct experimental groups: A, display abeta plaque pathology and express APPSwe/Ind at time of sacrifice; B, display abeta plaque pathology but do not express APPSwe/Ind at time of sacrifice; and C, do not display abeta plaque pathology but do express APPSwe/Ind at time of sacrifice. Stereologic investigation revealed decreased hippocampal volume in groups A(n=5) and B(n=5) when compared to group C(n=5) and age-matched wildtype (n=9)

Monte Carlo simulation of the Varian Clinac 600C accelerator dynamic and physical wedges

The present paper describes the study done on the dosimetric characteristics of the Varian Clinac 600C dynamic wedges (DW) and their comparison with the physical wedges (PW) in terms of the differences affecting the dose distributions, beam spectra, energy fluence and angular distributions. The geometry of the 4 MV photon beam and the dose distributions in a water phantom were simulated with GEANT3 and DPM Monte Carlo code systems. The DW was modelled through the constant movement of the upper jaws. The depth dose distributions and lateral profiles for the DW, PW and open fields were measured and compared with the Monte Carlo simulations and the global agreement was found to be within 3%. It was also found that the effects of a DW on beam spectral and angular distributions are much less significant than those produced by a PW. For example, in our study we found out that the 450PW, when compared with the corresponding open field, can introduce a 30% increase in the mean photon energy due to the beam hardening effect and that it can also introduce a 4.5% dose reduction in the build-up region because of the reduction of the contaminated electrons by the PW. For the DW neither this mean-energy increase nor such dose reduction was found. The PW, when compared to the DW, significantly alters the photon-beam spectrum and these dosimetric differences are significant and further investigation must be performed to quantify the impact in clinical use of these beams.info:eu-repo/semantics/publishedVersio

Reprodução assexuada de carobinha em função do tipo de estaca e uso de fito-hormônio.

O objetivo desta pesquisa foi verificar o surgimento de folhas e/ou raízes em função do tipo de estaca e solução de fito-hormônio na planta medicinal carobinha (Jacaranda decurrens). O experimento teve 4 tratamentos e 8 repetições totalizando 32 parcelas

Atividade ovicida in vitro dos óleos essenciais das plantas Eucalyptus stageiriana, Carapa guianensis, Cymbopogon martinii, Hura crepitans na inibição da eclodibilidade de nematóides gastrintestinais.

Objetivou-se nesse trabalho avaliar o efeito ovicida in vitro dos óleos essenciais de quatro plantas: E.stageiriana, C.guianensis, C.martinii, H.crepitans. No teste de eclosão foram utilizados tratamentos nas concentrações 5%-2,5%-1,25%-0,625%-0,312%.Cada ensaio foi acompanhado de um controle positivo contendo TWEEN 80 (3%) e um controle negativo somente água e ovo. Nas plantas H.crepitans e C.martinii as concentrações de 5% e 2,5%, não houve contagem em função da impossibilidade de visualização do material. Os resultados obtidos demonstram que H.crepitans e do C. martinii apresentam eficácia superior a 90% sugerindo que esses bioativos apresentam potencial para serem investigados quanta a sua eficácia na redução da carga parasitária em testes ?In vivo?

Infinite-cluster geometry in central-force networks

We show that the infinite percolating cluster (with density P_inf) of central-force networks is composed of: a fractal stress-bearing backbone (Pb) and; rigid but unstressed ``dangling ends'' which occupy a finite volume-fraction of the lattice (Pd). Near the rigidity threshold pc, there is then a first-order transition in P_inf = Pd + Pb, while Pb is second-order with exponent Beta'. A new mean field theory shows Beta'(mf)=1/2, while simulations of triangular lattices give Beta'_tr = 0.255 +/- 0.03.Comment: 6 pages, 4 figures, uses epsfig. Accepted for publication in Physical Review Letter

Qualidade pós-colheita de folhas secas de duas espécies medicinais no município de Manaus - AM.

O objetivo deste trabalho foi verificar a influência de duas origens de folhas de alfavaca e sacaca no teor e rendimento de óleo essencial