Intracellular staining with horseradish peroxidase (HRP) of physiologically identified corticospinal (CS) axons originating from the monkey motor cortex revealed the intraspinal morphology of their branching patterns. CS collaterals spread in a delta-like fashion in the intermediate zone and lamina IX. Virtually all CS axons examined terminated in lamina IX, and it was shown by labeling motoneurons with retrograde transport of HRP that individual CS axons made direct contacts with dendrites of motoneurons of different muscle species. 相似文献
Summary: This study describes the chain extension, with polycaprolactone diols, of polyurethane‐graft‐poly(butyl acrylate)s which were first prepared by the step growth polymerization of a mixture of diphenylmethane‐4,4′‐diisocyanate (MDI) and α,α′‐dihydroxyl‐poly(butyl acrylate)s. The success of the chain extension reaction was studied and confirmed by 1H NMR, SEC and DSC analysis. The incorporation of polycaprolactone sequences in the polyurethane chains modified their specific adhesive properties, bringing cohesion to the material, as demonstrated by tack measurements.
Summary The survival of grafts of dissociated allogeneic fetal neural dopamine (DA) rich tissue in the striatum has been studied after transplantation between inbred strains of mice differing at defined immunogenetical loci between donor and recipient. Six to 7 weeks and 15 weeks after grafting, surviving grafted DA neurons were found in the brains of all the recipients, albeit with a large variation in numbers, located either within the striatum or within the adjacent lateral ventricle. The mean number of surviving DA neurons did not differ between the syngeneic controls and the histoincompatible donor-host combinations, and there was no difference in survival between grafts that differed at single or multiple major histocompatibility complex (MHC) loci, and those that differed at multiple non-MHC loci. The amount of inflammatory cells in the graft area did not differ between the groups, and none of the animals showed massive infiltration of inflammatory cells. The in situ immunogenicity of the grafted neural tissue after intracerebral implantation was monitored by means of Simonsen's alloimmunization test, at 6–7 weeks after transplantation, which provides a sensitive measure primarily of the cellular immunological response. Most, but not all, graft recipients showed immunization with a Spleen Index (S.I.) close to that seen in recipients of an orthotopical skin graft of the same histoincompatibility combination. In contrast to the prolonged survival of the intracerebral neural transplants, none of the skin grafts survived longer than 3 weeks, thus demonstrating the immunologically privileged status of the brain. We conclude that intracerebrally grafted allogeneic neural tissue is capable of provoking a cellular immune response. Despite host immunization, however, the dissociated fetal neural allografts survived for at least 15 weeks without any overt signs of rejection, regardless of the donor-host combination used. 相似文献
Summary: The chromatographic analysis of hydrophilic copolymers is complicated due to the fact that in most cases aqueous eluents must be used. In aqueous eluents different polar and ionic effects may disturb the selective interactions between the macromolecules and the stationary phase making it impossible to separate such copolymers with regard to chemical composition. Therefore, 2D chromatography combining a separation according to composition with a separation according to molar mass has been applied mostly to polymers that are soluble in organic solvents. The present contribution describes experimental approaches to analyze such hydrophilic copolymers by 2D‐chromatography. For a model polymer system resulting from the copolymerization of methacrylic acid and a poly(ethylene glycol) macromonomer, it is shown that different analytical techniques including SEC, LC‐CC, MALDI‐TOF MS and 2D chromatography can be used to analyze the different parameters of molecular heterogeneity of such copolymers.
2D separation of poly(MPEG‐MM 2), 1st dimension: LC‐CC, 2nd dimension: SEC. 相似文献
Summary: After the condensation polymerization of benzoguanamine (BGA) and pyromellitic dianhydride (PMDA) under microwave irradiation, the resulting p‐π conjugate poly(amic acid) was grafted via the azo coupling reaction. The obtained side‐chain polymers were further grafted with TDI‐aliphatic alcohol derivatives and TDI‐aniline derivatives. The third‐order NLO coefficient and response time of PAA and graft polymers were measured by degenerated four wave mixing (DFWM) technique and their fluorescent properties were also investigated. All of the graft polymers have larger NLO coefficients and film‐formability than PAA. Their fluorescent properties were also changed by the different electronic effect of the side‐chains. The influences of the introduction of side‐chains, the side‐chain length and the electronic effect of the substituting groups on the azobenzol side‐chain to both optical properties of the polymers by varying the conjugation degree were investigated.