Morphological changes in axodendritic synapses of the leech during blocking of conduction in medium with reduced ionic concentration

Reactive changes were found by supravital staining with methylene blue in the synaptic system of the neuropil ofHirudo officinalis. They consist of marked bead-like deformation of the presynaptic portions, enlargement of the terminal structures, initial decolarization of the isthmuses between the boutons, and the clearer demonstration of the neurofibrils in the expanded postsynaptic dendrites. In a specially treated preparation of clearly identifiable axodendritic synapses of the leech it was shown that these changes reach a considerable magnitude when electrical activity in the ventral chain is blocked. This fact suggests that, together with other factors, they participate in the development of the conduction block.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 9, No. 6, pp. 613–618, November–December, 1977.     

Variability in host plant resistance of Sorghum to Striga Hermonthica infestation in West Africa

Fourteen elite sorghum lines were evaluated for their resistance to Striga hermonthica at three locations in Nigeria and Mali. Results showed that many of the lines especially MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64 (Keninkédié) and the check SRN 39 remained resistant to Striga in all locations with low emerged Striga counts, while SAMSORG 14 had the highest Striga infestation in all locations. Considerable variation in reaction to Striga infestation was observed on Séguètana, 97-SB-F5DT-63 (Wasa), 97-SB-F5DT-65, CMDT 38, CMDT 39 and CMDT 45 which were susceptible to Striga at Samaru, Nigeria but were resistant to Striga at both locations in Mali. Based on low Striga resistance and high grain yield, lines MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64, 97-SB-F5DT-65, CMDT 39 and SAMSORT 14 have been nominated for wider evaluation across more West African countries.     

Two common nonsynonymous paraoxonase 1 (<Emphasis Type="Italic">PON1</Emphasis>) gene polymorphisms and brain astrocytoma and meningioma

Background  

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.     

Long-term effects of graduated compression stockings on cardiorespiratory performance

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.     

Glio-neuronal and glio-glial syncytial cytoplasmic connections in peripheral nerve trunks of the crayfish <Emphasis Type="Italic">Astacus leptodactylus</Emphasis>

The paper considers various aspects of glial sheaths of neurites in the crayfish peripheral nerve trunks and roots. There are revealed dotted glio-neuritic tight junctions and a varicose deformation of the intercellular glio-neuritic cleft. Rupture of membranes in the area of contact leads to formation of the glio-neuritic pore (less than 10 nm) that is enlarged and forms wide (up to 240 nm) syncytial perforations. At the edge of perforation, either remnants of tight junctions are present or damaged membranes that fuse and become rounded. The lumen of perforations always contains residual membranous bodies in the form of vesicles. Their deviation from the median line can indicate a mutual translocation of substances of the glio- and neuroplasm. In the adjacent layers of the multilayer glial sheath there is noted a similar phenomenon of formation of the glio-glial syncytial connection terminating by fusion of neighbor glial layers, which is terminated by fusion of neighbor glial layers into the single lamina. The process begins from the varicose deformation of interglial clefts, which appears as a result of massive formation of dotted and expanded tight membranous contacts. As a result of transformation of ellipsoid varicose deformations into the spherical ones, syncytial pores (less than 10 nm) between them are formed, which are enlarged and break the paired gliolemmae into fragments. As a result, the adjacent glial layers are united. Since this process in intact animals occurs on the background of undamaged nerve structures, a suggestion is put forward about its reversibility and the functional nature.     

Syncytial perforations of human embryo membranes

An electron microscopy study of the anlage of cerebral cortex of human embryo has been carried with the aim of determining the presence of syncytial interneuronal connections in embryogenesis. It has been determined that, in part of the neurons, the glial embryo is absent and their external cell membranes are directly attached to each other by forming elongated or dotted tight junctions. Sometimes these junctions are perforated and, on their basis, the true syncytial interneuronal connections are formed. Natural structural properties of these connections are the following: formation of the base of tight membrane contacts, obligatory rounding of perforation edges, and the presence of residual particles in the form of spherical vesicles in the lumen of perforations. Results obtained allowed us to conclude that, in the anlage of cerebral cortex of embryos obtained during surgical abortion of pregnancy, apart from the formation of synaptic contacts, or until their formation, there is the possibility of syncytial interneuronal connections appearing. This should be considered during the transplantation of the developing brain.