Neurovascular developmental interaction: a specific form of vascular maldevelopment in the malformed brain

The process of the development of the intracranial vessels was studied by means of immunohistochemical analysis of factor VIII in normal and exencephalic chick fetuses. The results revealed that the development of blood vessels in exencephalic brain was far advanced beyond the norm, with intense immunoreactivity to factor VIII on postincubation day 16 exceeding that on day 21 in normal controls. Compared with results regarding the direction of the overgrowth in the neuronal maturation process in the previous study using the chick exencephaly model, the findings of overmatured blood vessels were compatible with NSE- and somatostatin-positive elements that appeared especially in the overgrowth foci. The results of the present study suggested the pathogenic development of the area cerebrovasculosa in the neural placode as a phenomenon consequent upon hypervascularization in response to neuronal overgrowth, as seen in human cases of exencephaly or anencephaly. We emphasize the significance of this specific phenomenon in the development of the fetal central nervous system, namely neurovascular developmental interaction.     

Effect of low concentrations of K+ and Cl− on the Na+-dependent neuronal uptake of [3H] dopamine

The specific uptake of [³H] dopamine (DA) was studied using a crude synaptosomal fraction obtained from rat striatum. In a medium containing a 10 mM NaHC03/NaH2PO4 buffer and no added K⁺ ions, addition of NaCl elicited an increase in DA uptake for Na⁺ concentrations from 10 to 60 mM, and then a decrease of uptake for Na⁺ concentrations up to 130 mM. These data confirm that rather low NaCl concentrations produce a maximal DA uptake. This biphasic curve of uptake resulted from significant changes in the V _max of the DA uptake. Except for 10 mM Na⁺, this curve was not significantly modified when 9 mM NaHCO₃/NaH₂PO₄ were replaced by 9 mM NaCl. This result indicates that the Cl^– dependence of the DA uptake is mainly secondary to the Na⁺ dependence. Addition of KCl up to 3 mM did not modify the ascending part of the NaCl-dependent uptake curve. In contrast, the reduction in uptake produced by high Na⁺ concentrations was prevented in a concentration-dependent manner by KCl; this effect resulted from a decrease in the K_m and an increase in the V _max for the uptake.Measurements of membrane potential, with the help of the fluorescent probe 3,3-diethylthiadicarbocyanine iodide [DiSC₂(5)] and purified synaptosomes prepared from rat striatum and cerebral cortex, revealed that addition of 3 mM KCl to a medium containing a high Na⁺ concentration and no K⁺ ions produced a marked and stable decrease in the fluorescence level. This decrease which corresponds to an increase in membrane polarization was blocked by 0.1 mM ouabain. These data suggest that low K⁺ concentrations are likely to prevent the decrease in uptake elicited by high Na⁺ concentrations by restoration, via a Na⁺/K⁺ ATPase-mediated mechanism, of the membrane potential and/or a transmembrane electrochemical Na⁺ gradient more favourable to DA uptake.     

Formation of “neo-cortex” in a congenital human teratoma

Summary A congenital human teratoma contained a neuroectodermal mass with architectonic features similar to those of the normal developing neo-cortex. Surrounding a central cavity, a germinal, an intermediate and a cortical zone were clearly distinguishable from innermost to outermost. Glial fibers coursed radially through the intermediate and cortical zones. In the cortical plate neuronal elements were oriented radially with an inside out gradient of differentiation. Mesothelial tissue covered the outer surfaces of the cortex. Over limited sectors a gap in the integrity of the meso-glial barrier were associated with neuroglial ectopias.The following points are of neurobiologic importance: the formation of the miniature cerebral cortex occurred in the absence of any influence of afferent subcortical fibers. The radial alignment of glial fibers between the germinal pseudostratified epithelium and the outer surface occurred only in sectors of the neuro-ectodermal mass where a neo-cortex was present, and may therefore have been a critical determinant in the formation of the cortical plate. The integrity of the outer glial mesenchymal barrier may be necessary for the normal arrangement of cortical neurons.     

In vitro studies on 6-fluoronoradrenaline at several peripheral sympathetic neuroeffector junctions

Summary A comparison of the effects of noradrenaline and 6-fluoronoradrenaline has been made at several peripheral sympathetic neuroeffector junctions. In the rat vas deferens preparation in the presence of 1 M cocaine, 6-fluoronor-adrenaline was found to be about 9 times more potent than noradrenaline as an agonist at presynaptic inhibitory ₂-adrenoceptors. In the rabbit aorta, 6-fluoronoradrenaline had approximately one tenth of the potency of noradrenaline in stimulating the postsynaptic ₁-adrenoceptors. Furthermore 6-fluoronoradrenaline, in contrast to previous reports, appears to be a substrate for the neuronal uptake process since exposure to cocaine potentiated the inhibition of the twitch response of the vas deferens by 6-fluoronoradrenaline. In addition, 6-fluoronoradrenaline increased the spontaneous outflow of radioactivity from rabbit pulmonary artery strips prelabelled with ³H-noradrenaline and this increase was blocked by cocaine (30M).These results demonstrate that 6-fluoronoradrenaline is a preferential ₂-adrenoceptor agonist which is a substrate for the neuronal uptake process in peripheral sympathetically innervated smooth muscle preparations.     

Neuropathological findings of an autopsy case of adult β-galactosidase and neuraminidase deficiency

Summary An autopsy case of a Japanese male with familial -galactosidase and neuraminidase deficiency is reported. The clinical picture was characterized by adult onset, a gargoyle-like face, cerebellar ataxia, myoclonus, convulsions, retinal degeneration and cortical blindness.Histopathologically, most neurons seemed to have become degenerated in the whole cerebral cortex. Moreover, the calcarine cortex appeared spongy with depopulation of nerve cells. Stuffed neurons or neuronal storage changes were found throughout the brain, especially in the motor nuclei of the spinal cord and brain stem.The inclusions in the stuffed neurons revealed various profiles on the electron microscope. They were composed of membranous lamellar and/or multilamellar structures, often accompanying vacuoles and reminiscent of lipofuscin-like profiles.     

Cerebral protection by AMPA- and NMDA-receptor antagonists administered after severe insulin-induced hypoglycemia

Summary Excitatory amino acids are implicated in the development of neuronal cell damage following periods of reversible cerebral ischemia or insulin-induced hypoglycemic coma. To explore the importance of glutamate receptor activation in the posthypoglycemic phase, we exposed rats to 20 min of insulin-induced severe hypoglycemia. The rats were treated immediately after the hypoglycemic insult with four regimes of glutamate receptor antagonists: (1) the AMPA (-amino-3-hydroxy-5-methyl-4-isoxazole propriate)-receptor antagonist NBQX [2.3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline] given as a bolus dose of 30 mg · kg^-1 i.p., followed by an i.v. infusion of 225 g · kg^-1 · min^-1 for 6 h; (2) the non-competitive NMDA-receptor antagonist, dizocilpine (MK-801) 1 mg · kg^-1 given i.v.; (3) a combined NBQX treatment, (a bolus dose of 10 mg · kg^-1 i.p., followed by an i.v. infusion of 225 g · kg^-1 · min^-1 for 6 h), with dizocilpine 0.33 mg · kg^-1 given twice i.p. at 0 and 15 min after recovery and (4) the competitive NMDA-receptor blocker CGP 40116 [D-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid] 10 mg · kg^-1 given i.p.. In the striatum, all glutamate receptor blockers significantly decreased neuronal damage by approximately 30%. An approximately 50% decrease in neuronal damage was demonstrated in neocortex and hippocampus following the combined treatment with NBQX and dizocilpine, while protection was variable following the treatment with a single glutamate-receptor antagonist. We conclude that neuronal damage continues to develop in the striatum and in cortical brain regions in the posthypoglycemic period and that both NMDA- and AMPA-receptors contribute to this process, possibly by a change in the cellular response to both AMPA- and NMDA-receptor stimulation.     

Effects of nicotine receptor agonists on acetylcholine release from the isolated motor nerve,small intestine and trachea of rats and guinea-pigs

Summary The effects of nicotine receptor agonists on the release of [³H]acetylcholine from the phrenic nerve, the small intestine and the trachea were investigated to characterize neuronal nicotine receptors within the peripheral nervous system. Contraction of the indirectly-stimulated hemidiaphragm was recorded to investigate desensitization of the postsynaptic muscular nicotine receptors. Nicotine, cytisine, 1,1-dimethyl-4-phenylpiperazinium and 2-(4-aminophenyl)-ethyl-trimethyl-ammoniumiodide caused a concentration-dependent (0.1–30 M) increase in evoked [³H]acetylcholine release from the phrenic nerve, whereby bell-shaped concentration-response curves were obtained. The rank order of decreasing potency was: nicotine > cytisine > 1,1-dimethyl-4-phenylpiperazinium > 2-(4-aminophenyl)-ethyl-trimethyl-ammoniumiodide. The presynaptic effects of nicotine depended strongly on the exposure time: facilitation occurred after a short 20 s exposure and inhibition after a 3 min exposure, whereas nicotine no longer affected evoked [³H]acetylcholine release after a 15 min exposure. Pre-exposure (40 min) of the phrenic nerve to 0.3 M nicotine prevented any subsequent modulatory effect of a high nicotine concentration. In contrast, the contraction of the indirectly-stimulated hemidiaphragm remained unaffected in the presence of 0.3–30 M nicotine, but a concentration of 1 mM nicotine abolished skeletal muscle contraction. Nicotine (10 M) produced a substantial release of [³H]acetylcholine in the small intestine but not in the isolated trachea. The present experiments show presynaptic nicotine receptors at the phrenic nerve, which, under appropriate conditions, can mediate facilitation of evoked transmitter release. These neuronal receptors appear more sensitive to desensitizing conditions than the postsynaptic muscular nicotine receptors. Nicotine also mediates a transient release of acetylcholine in the myenteric plexus but not in the trachea, and as a consequence, applied nicotine preferentially activates smooth muscle activity in the intestine.Abbreviations DMPP 1,1-dimethyl-4-phenylpiperazinium - PAPETA 2-(4-aminophenyl)-ethyl-trimethylammoniumiodiderine of [³H]acetylcholine release     

The initiation of voluntary movements by the supplementary motor area

Summary The hypothesis is formulated that in all voluntary movements the initial neuronal event is in the supplementary motor areas (SMA) of both cerebral hemispheres.Experimental support is provided by three lines of evidence. 1. In voluntary movements many neurones of the SMA are activated probably up to 200 ms before the pyramidal tract discharge. 2. Investigations of regional cerebral blood flow by the radioactive Xenon technique reveal that there is neuronal activity in the SMA of both sides during a continual series of voluntary movements, and that this even occurs when the movement is thought of, but not excuted. 3. With voluntary movement there is initiation of a slow negative potential (the readiness potential, RP) at up to 0.8 s before the movement. The RP is maximum over the vertex, i.e. above the SMA, and is large there even in bilateral Parkinsonism when it is negligible over the motor cortex.An account is given of the SMA, particularly its connectivities to the basal ganglia and the cerebellum that are active in the preprogramming of a movement. The concept of motor programs is described and related to the action of the SMA. It is proposed that each mental intention acts on the SMA in a specific manner and that the SMA has an inventory and the addresses of stored subroutines of all learnt motor programs. Thus by its neuronal connectivities the SMA is able to bring about the desired movement.There is a discussion of the manner in which the mental act of intention calls forth neural actions in the SMA that eventually lead to the intended movement. Explanation is given on the basis of the dualist-interactionist hypothesis of mind-brain liaison. The challenge is to the physicalists to account for the observed phenomena in voluntary movement.Dedicated to Prof. Richard Jung on the occasion of his 70th birthday     

不同极性溶媒瑞香狼毒提取物的抗肿瘤活性比较

目的：通过比较不同极性溶媒瑞香狼毒提取物的体外抗肿瘤活性，确定瑞香狼毒抗肿瘤活性成分所在的极性区间。方法：采用索氏回流提取法，依次用石油醚、乙酸乙酯、丙酮和乙醇对狼毒进行回流提取，并用不同浓度的各溶剂提取物分别处理Eca109、K562、HepG_2细胞株，通过MTT检测法，比较各溶媒提取物对肿瘤细胞的抑制活性。结果：石油醚提取物和乙酸乙酯提取物对体外培养肿瘤细胞表现出较强的抑制作用，在测定浓度范围内呈现出良好剂量依赖性，石油醚提取物最大抑制率分别为78％(Eca-109)、93％(K562)、95％(HepG_2)，乙酸乙酯提取物最大抑制率分别为53％(Eca-109)、91％(K562)、87％(HepG_2)；而丙酮和乙醇提取部位在测定浓度范围内则显示出很弱的抑制作用；在各提取物中石油醚提取物的体外抗肿瘤作用最强。结论：石油醚提取成分是瑞香狼毒中体外抗肿瘤活性最强的部位。     

In situ and immunocytochemical localization of E-FABP mRNA and protein during neuronal migration and differentiation in the rat brain

The present study compares the temporal-spatial expression and tissue localization of the rat epidermal type fatty acid binding protein (E-FABP) (DA11/C-FABP/S-FABP/LEBP/KLBP) in the developing rat central nervous system (CNS). In situ hybridization (ISH) and immunocytochemistry (ICC) studies demonstrate that mRNA E-FABP and protein are expressed at high levels during neurogenesis, neuronal migration, and terminal differentiation. Migrating pyramidal cells in the cerebral cortex, Purkinje cells and deep nuclear neurons in the cerebellum, and neurons in the olfactory bulb and retina exhibited a strong E-FABP-like immunoreactivity (E-FABP-LI) throughout the entire process of differentiation and migration. The levels of E-FABP mRNA and protein were dramatically higher in prenatal and early postnatal neurons, as compared to adult neurons. The E-FABP antibody immunoreacted with growing neurites, and nuclear and cytoplasmic regions of neurons. The intracellular multiregional pattern of localization of E-FABP and its differential temporal expression during development, are consistent with its proposed role in transporting long chain free fatty acids and/or other hydrophobic ligands during neuronal differentiation and axon growth.