Acetylcholine: fast axoplasmic transport in insect chemoreceptor fibers

Acetylcholine is transported along insect chemoreceptor axons at a rate of 12 to 13 centimeters per day after peripheral uptake of choline. Colchicine, vinblastine sulfate, and cytochalasin B all block transport, but transport continues in axons separated surgically from the cell body. These data from an insect are in accord with many studies on vertebrates which have implicated intracellular microtubules in the transport mechanism. The peripheral uptake of choline and its acetylation and transport to nerve terminals in the brain are consistent withthe suggestion that acetylcholine is an antennal sensory transmitter in insects.     

Fast transport system of materials in mammalian nerve fibers

A fast transport system of materials is shown in cat sensory fibers of sciatic nerve. After injection of tritiated leucine into the lumbar seventh ganglia, the distribution of activity was measured in the sciatic nerves from 2 to 8 hours afterward. The distribution showed a crest of activity advancing down the fibers at a rate of approximately 410 millimeters per day. An intraaxonic locus of the activity was indicated by a block of the downflow induced by local freezing which causes the fibers to close off. Some of the activity in the nerve was due to free tritiated leucine, with most of it incorporated into polypeptide, soluble protein, and subcellular particulates.     

Axonal transport of gangliosides in the goldfish optic nerve

Radioactive glucosamine and N-acetylmannosamine injected into the goldfish eye are incorporated into gangliosides that undergo rapid axonal transport to the optic nerve terminals. All ganglioside fractions are labeled. These data provide the first evidence that axonal transport has a role in neuronal ganglioside function and metabolism.     

Molecular basis for the nerve dependence of limb regeneration in an adult vertebrate

The limb blastemal cells of an adult salamander regenerate the structures distal to the level of amputation, and the surface protein Prod 1 is a critical determinant of their proximodistal identity. The anterior gradient protein family member nAG is a secreted ligand for Prod 1 and a growth factor for cultured newt blastemal cells. nAG is sequentially expressed after amputation in the regenerating nerve and the wound epidermis-the key tissues of the stem cell niche-and its expression in both locations is abrogated by denervation. The local expression of nAG after electroporation is sufficient to rescue a denervated blastema and regenerate the distal structures. Our analysis brings together the positional identity of the blastema and the classical nerve dependence of limb regeneration.     

Junctional physiology and motor nerve distribution in the fast adductor muscle of the scallop

Electrical recordings from single muscle cells in the fast portion of the scallop adductor have revealed a multiterminal distribution of motor nerves. All motor junctions appear to be of the fast designation, and several nerve fibers supply each muscle cell. The muscle fibers, by virtue of common innervation, are grouped into functional motor units. The pattern of innervation in scallops thus shares functional similarities with the motor distribution to skeletal muscle fibers of both vertebrates and arthopods.     

Rapid and precise down regulation of fast axonal transport of transmitter in an identified neuron

Within 1 day after the removal of one branch of the bifurcated axon of an identified neuron in Aplysia, the cell body reduced its output of transmitter storage vesicles to adjust precisely for the decreased need. This adjustment terminated the initial consequence of the removal, the transport of an inappropriately large number of vesicles to the remaining synapses. The most likely cause of the reduction of transport of transmitter is the loss of information normally provided by the disconnected axon or synapses.     

Modulation of memory processing by cholecystokinin: dependence on the vagus nerve

Allowing mice access to food immediately after an aversive training session enhances memory retention. Cholecystokinin-octapeptide (CCK-8), which is a gastrointestinal hormone released during feeding, also enhances memory retention when administered intraperitoneally. This memory-enhancing effect of CCK-8 is blocked when the vagus nerve is cut, indicating that CCK-8 may produce its effect on memory retention by activating ascending fibers in the vagus nerve. Thus, CCK-8, a peripherally acting peptide, may mediate the memory-enhancing effects of feeding.     

Synaptic transmission depressed by colchicine blockade of axoplasmic flow

Colchicine, which inhibits axoplasmic transport and induces organelle alterations in nerve terminals, was injected intraocularly in pigeons. Electrical stimulation of the optic nerve yielded normal evoked potentials in retinotectal fibers, whereas postsynaptic responses recorded in the tectum were reduced. Postsynaptic depression suggests a deficit of synaptic transmission, presumably dependent on colchicine interference with migrating material.     

洪灾经济损失快速评估的混合式模糊神经网络模型

针对洪水灾害和洪灾损失评估的特点,采用混合式模糊神经网络数学模型对一典型流域洪灾经济损失进行评估,并且与BP网络评估损失模型进行了比较。虽然混合式模糊神经网络模型在洪水经济损失评估中是初次尝试,但评估结果表明模型从收敛速度和评估精度都取得了较好的效果,为洪水经济损失评估提供了新的方法、新的思路。     

Polymers with cavities tuned for fast selective transport of small molecules and ions

Within a polymer film, free-volume elements such as pores and channels typically have a wide range of sizes and topologies. This broad range of free-volume element sizes compromises a polymer's ability to perform molecular separations. We demonstrated free-volume structures in dense vitreous polymers that enable outstanding molecular and ionic transport and separation performance that surpasses the limits of conventional polymers. The unusual microstructure in these materials can be systematically tailored by thermally driven segment rearrangement. Free-volume topologies can be tailored by controlling the degree of rearrangement, flexibility of the original chain, and judicious inclusion of small templating molecules. This rational tailoring of free-volume element architecture provides a route for preparing high-performance polymers for molecular-scale separations.     

Retrograde axonal transport of endogenous proteins in sciatic nerve demonstrated by covalent labeling in vivo

Extracellularly applied N-succinimidyl [2,3-3H]propionate was used in vivo to covalently label intra-axonal proteins in the rat sciatic nerve. This technique permitted a unique view of axonal transport of proteins independent of biosynthesis. The proteins detected in slow anterograde transport (1 to 2 millimeters per day) correspond to cytoskeletal proteins described in previous papers. The slowly retrogradely transported component (3 to 6 millimeters per day) was composed primarily of a single protein with a molecular weight of 68,000.     

Vitamin K and coumarin anticoagulants: dependence of anticoagulant effect on inhibition of vitamin K transport

Coumarin anticoagulants inhibit the release of plasma clotting factor VII by vitamin K in liver slices from vitamin K-deficient animals without inhibition of protein synthesis. When the ratio of vitamin K to coumarin anticoagulant is kept constant, but the concentrations are increased, the inhibition disappears. This suggests that the pharmacological action of coumarin anticoagulants depends on irreversible inhibition of normal vitamin K transport to its site of action. At higher concentrations of vitamin K the inhibition can be surmounted, because vitamin K can enter the cell by an alternate route that is not inhibited by coumarin anticoagulants.     

Alcohol dependence and opiate dependence: lack of relationship in mice

According to a recently proposed hypothesis, physical dependence upon alcohol is due to the formation of an endogenous opiate. We tested the hypothesis by determining whether or not ethanol-dependent mice would show typical opiate-dependent behavior (withdrawal jumping syndrome) when challenged with the opiate antagonist naloxone. Our results do not support the hypothesis.     

作物叶酸代谢工程

叶酸是指四氢叶酸及其衍生物的一类物质,是介导一碳单位转移的重要辅助因子。人体自身不能合成叶酸,必须从食物中获取。当人体叶酸缺乏时,贫血、神经系统疾病、心血管病及癌症等发病率显著增加。结合本实验室的工作,系统阐述了番茄、水稻和玉米作物的叶酸代谢工程研究策略以及研究进展,对叶酸合成前体喋呤和对氨基苯甲酸(PABA)含量与叶酸合成之间的关系进行了深入分析,并对今后叶酸代谢工程的发展进行了展望。     

晕清降压方对代谢性高血压部分代谢组分的影响

目的 观察晕清降压方对代谢性高血压部分组分的影响,并探讨其降压的作用机制。方法 将90例代谢性高血压患者随机分为观察组60例、对照组30例。对照组：西医基础治疗;观察组：晕清降压方治疗。于4周后统计分析两组患者治疗前后血脂、血尿酸、血压的变化。结果 观察组在改善代谢紊乱优于对照组,差异有统计学意义（P<0.05）,观察组在降压上与对照组相比,差异无统计学意义（P>0.05）。结论 晕清降压方在降低血压的同时,可有效改善代谢性高血压部分代谢组分,其降低血压的机制可能与改善其代谢异常组分,减轻代谢异常成分对血管造成的损害,恢复血管顺应性,降低血管阻力有关。