Cortical control of anticipatory postural adjustments prior to stepping.

Human bipedal balance control is achieved either reactively or predictively by a distributed network of neural areas within the central nervous system with a potential role for cerebral cortex. While the role of the cortex in reactive balance has been widely explored, only few studies have addressed the cortical activations related to predictive balance control. The present study investigated the cortical activations related to the preparation and execution of anticipatory postural adjustment (APA) that precede a step. This study also examined whether the preparatory cortical activations related to a specific movement is dependent on the context of control (postural component vs. focal component). Ground reaction forces and electroencephalographic (EEG) data were recorded from 14 healthy adults while they performed lateral weight shift and lateral stepping with and without initially preloading their weight to the stance leg. EEG analysis revealed that there were distinct movement-related potentials (MRPs) with concurrent event-related desynchronization (ERD) of mu and beta rhythms prior to the onset of APA and also to the onset of foot-off during lateral stepping in the fronto-central cortical areas. Also, the MRPs and ERD prior to the onset of APA and onset of lateral weight shift were not significantly different suggesting the comparable cortical activations for the generation of postural and focal movements. The present study reveals the occurrence of cortical activation prior to the execution of an APA that precedes a step. Importantly, this cortical activity appears independent of the context of the movement.

New allene synthesis via carbocupration-zinc carbenoid homologation and beta-elimination sequence.

[reaction: see text] Polysubstituted propadienes are obtained in good to excellent yields by the consecutive carbocupration-homologation-beta-elimination reactions on the easily accessible alkynyl sulfoxides or sulfones. This one-pot reaction also allows the preparation of functionalized allenes.

Origin of nuclear aberrations and seed shrivelling in triticale: a re-evaluation of the role of C-heterochromatin.

The effect of C-heterochromatin on the origin of nuclear aberrations and seed shrivelling was investigated in four triticale lines, each consisting of a pair of genotypes designated A (producing plump, well-filled seeds) and B (with shrivelled seeds). The relative DNA content in the polyploid nuclei of endosperms, 42 h after pollination, was estimated by Feulgen cytophotometry. The observed frequency of polyploid nuclei, 0.85% and 5.69%, respectively, in the two genotypes 1A and 1B caused a reduction in nuclear number of 3.27% and 18.54% at this stage of development. In the B genotype, producing shrivelled grains, polyploidisation started earlier than in the A genotype. An examination of the Giemsa karyotype of the mitotic chromosomes of the rye genome in the four triticale pairs revealed no considerable differences in the banding pattern between the A and B genotypes. Giemsa staining of endosperms, 2-3 days after pollination, clearly showed that bridges without bands, most probably involving wheat chromosomes, were also present. An experiment designed to simulate spindle disturbances in developing endosperms by colchicine treatment revealed that polyploid nuclei can be formed by spindle malfunctions as well.

Right aortic arch with isolation of the left innominate artery.

Isolation of the left innominate artery and right aortic arch, a rare variant of right aortic arch anomalies, was diagnosed in a four-year-old boy with other congenital cardiac anomalies. Isolation of vessels from the aortic arch is predicted from the primitive double aortic arch model of Edwards. In this patient there was no evidence of a vascular ring or of a significant subclavian steal syndrome.