RESUMO
Deposits similar to corpora amylacea were observed by electron microscopy and light microscopy within thin myelinated axons in the spinal gray matter in various diseases. By electron microscopy the deposits consisted of randomly interlacing short linear structures of various thickness which were different from tangles of neurofilaments. Sometimes they contained dense granules and electron-dense floccules. Though their incidence was relatively high in some cases of degenerative or metabolic disease of the central nervous system, they were not specific to any disease but seemed to be related to aging, indicating a peculiar aspect of chronic degeneration of the axons.
Assuntos
Amiloide/análise , Axônios/ultraestrutura , Corpos de Inclusão/ultraestrutura , Medula Espinal/ultraestrutura , Adolescente , Adulto , Idoso , Envelhecimento , Astrócitos/ultraestrutura , Doenças do Sistema Nervoso Central/patologia , Feminino , Glicoproteínas , Glicosaminoglicanos , Humanos , Masculino , Pessoa de Meia-Idade , Bainha de Mielina/ultraestrutura , Degeneração Neural , Fibras Nervosas Mielinizadas/ultraestruturaRESUMO
We have searched for Theta+(1540) and Xi(--)(1862) pentaquark candidates in proton-induced reactions on C, Ti, and W targets at midrapidity and square root of s = 41.6 GeV. In 2 x 10(8) inelastic events we find no evidence for narrow (sigma approximately 5 MeV) signals in the Theta+ --> pK0(S) and Xi(--) --> Xi- pi- channels; our 95% C.L. upper limits (UL) for the inclusive production cross section times branching fraction B dsigma/dy/(y approximately 0) are (4-16) mub/N for a Theta+ mass between 1521 and 1555 MeV, and 2.5 mub/N for the Xi(--). The UL of the yield ratio of Theta+/Lambda(1520) < (3-12)% is significantly lower than model predictions. Our UL of B Xi(--)/Xi(1530)0 < 4% is at variance with the results that have provided the first evidence for the Xi(--).