Crypts are the site of intestinal fluid and electrolyte secretion

The site of adenosine 3',5'-monophosphate-mediated fluid and electrolyte secretion across mammalian large intestine was found to be the crypts of Lieberkühn by means of two techniques. First, the formation of fluid droplets was visualized on the oil-covered mucosal surface directly over crypt duct openings when secretion was stimulated. Second, microelectrode impalement of individual surface and crypt cells revealed that only crypts cells produced a pattern of secretagogue induced alterations in membrane potential and resistance that was characteristic of secretory epithelia.     

Property of cerebrospinal fluid associated with disturbed metabolism of central nervous system

Cerebrospinal fluid was assayed for the capacity to contract smooth muscle and for the capacity to develop such activity when incubated with globulin. Activity was observed in fluid collected from patients with inflammatory or degenerative disease of the central nervous system, sustained intracranial vasodilatation, sustained noxious stimulation, or chronic schizophrenia. Control specimens lacked measurable activity.     

Complexity and the nervous system

Advances in the neurosciences have revealed the staggering complexity of even "simple" nervous systems. This is reflected in their function, their evolutionary history, their structure, and the coding schemes they use to represent information. These four viewpoints need all play a role in any future science of "brain complexity."     

Biochemistry of information storage in the nervous system

The use of molecular biological approaches has defined new mechanisms that store information in the mammalian nervous system. Environmental stimuli alter steady-state levels of messenger RNA species encoding neurotransmitters, thereby altering synaptic, neuronal, and network function over time. External or internal stimuli alter impulse activity, which alters membrane depolarization and selectively changes the expression of specific transmitter genes. These processes occur in diverse peripheral and central neurons, suggesting that information storage is widespread in the neuraxis. The temporal profile of any particular molecular mnemonic process is determined by specific kinetics of turnover and by the geometry of the neuron resulting in axonal transport of molecules to different synaptic arrays at different times. Generally, transmitters, the agents of millisecond-to-millisecond communication, are subject to relatively long-lasting changes in expression, ensuring that ongoing physiological function is translated into information storage.     

副溶血性弧菌Ⅲ型分泌系统与Ⅵ型分泌系统的研究进展

副溶血性弧菌(Vibrio parahaemolyticus,VP)是一种常见的革兰氏阴性细菌,主要分布在海洋、海口和河口沉积物中,能够引起人急性肠胃炎、伤口感染和败血症,同时危害水产品养殖业。由该菌引起的食物中毒事件在全世界范围内频繁发生,该菌被认为是微生物性食物中毒的主要病原菌之一。影响副溶血性弧菌致病性的毒力因素包括溶血素、黏附因子、分泌系统等,尤其在分泌系统中,Ⅲ型分泌系统(TypeⅢsecretion systems, T3SS)和Ⅵ型分泌系统(T6SS)与副溶血性弧菌致病性密切相关。T3SS是一种多亚基针状结构,将分泌蛋白通过供体细胞质直接注入受体细胞质;T6SS是一种接触依赖性蛋白分泌装置,将毒素直接注入目标细胞内。通过对Ⅲ型分泌系统和Ⅵ型分泌系统的研究进展进行梳理,从这两种分泌系统的结构出发,并对其功能和调控机制分别进行分析比较,指出了二者在效应蛋白及产生毒素上的不同,找出了二者与副溶血性弧菌定植的关系,以期通过这两者的联系进而深入了解副溶血性弧菌的致病机制,为防治该菌提供科学指导。     

秦香止泻方对HRV腹泻乳鼠小肠黏膜一氧化氮浓度的影响

目的研究秦香止泻方对人轮状病毒()腹泻乳鼠小肠黏膜一氧化氮(NO)浓度的影响,探讨该方干预HRV腹泻的作用机制。方法将192只出生3～5 d的乳鼠随机分为空白组,模型组,病毒唑组,秦香止泻方低、中、高剂量组,每组32只,空白组经口灌入不含HRV的培养液,其余各组经口灌入50μL(3.0×108PFU/mL)的Wa株HRV培养液。接种病毒12 h后,各给药组每只乳鼠经口给予相应的秦香止泻方药液50μL,病毒唑组给予同体积的病毒唑,空白组和模型组分别给予同体积的蒸馏水。连续给药8 d后用金胶体试纸方法检测粪便HRV抗原,观察一般情况和腹泻评分,采用微板法测定小肠黏膜NO浓度,并对腹泻评分与NO浓度进行相关性分析。结果接种病毒后第2天开始出现不同程度的腹泻,与模型组和病毒唑组比秦香止泻方能明显缩短腹泻病程,减轻腹泻程度,呈现一定的量效关系,差异有统计学意义(P<0.05);模型组与空白组比较,NO浓度明显升高,差异具有统计学意义(P<0.01),秦香中、高剂量组与模型组比较,第1～6天,NO浓度均显著降低(P<0.01),秦香高、中剂量组与病毒唑组比,第1～5天NO浓...     

Immunological approaches to the nervous system

Immunology has had a major impact on neurobiology, expanding dramatically the number of subjects amenable to investigation. Studies with antibodies to neuropeptides, transmitters, and transmitter enzymes have disclosed a great heterogeneity among neurons and have provided clues for interpreting anatomical connections. Monoclonal antibodies are being used to identify functionally related subpopulations of neurons and cell lineages in development and to study mechanisms by which axons grow along stereotypic pathways to reach their targets. Other antibodies have identified molecules that appear to participate in cell aggregation, cell migration, cell position, and axon growth. Antibodies have revealed that many proteins are concentrated in anatomically distinct regions of the neuron. Moreover, these studies have suggested that individual proteins have different antigenic epitopes shielded or modified in different parts of the same neuron. Antibodies to membrane proteins crucial for neuronal function, such as ion pumps, ion-selective channels, and receptors, have been used to map their distributions and to study their structures at high resolution.     

Promoting functional plasticity in the damaged nervous system

Damage to the central and peripheral nervous system often produces lasting functional deficits. A major focus of neuroscience research has been to enhance functional restitution of the damaged nervous system and thereby produce recovery of behavioral or physiological processes. Promising procedures include surgical, physical, and chemical manipulations to reduce scar formation and minimize the disruption of support elements, administration of growth-stimulating substances, tissue grafts to bridge gaps in fiber pathways, and embryonic brain tissue grafts to provide new cells with the potential to generate fiber systems. Two elements are required for functional nervous system repair: (i) neurons with the capacity to extend processes must be present, and (ii) the regenerating neurites must find a continuous, unbroken pathway to appropriate targets through a supportive milieu.     

Retrograde axonal transport in the central nervous system

When horseradish peroxidase is injected into the optic tectum of a chick, axons of ganglion cells transport it centripetally to their cell bodies in the retina at a rate of about 72 millimeters per day. After intraocular injections in the young chick, the peroxidase is transported centripetally along efferent axons, and is concentrated in cell bodies within the isthmo-optic nucleus. This retrograde movement of protein from axon terminal to cell body suggests a possible mechanism by which neurons respond to their target areas.     

Sexual differentiation of the central nervous system

Sexual differentiation of reproductive and behavior patterns is largely effected by hormones produced by the gonads. In many higher vertebrates, an integral part of this process is the induction of permanent and essentially irreversible sex differences in central nervous function, in response to gonadal hormones secreted early in development.     

Transneuronal transfer of radioactivity in the central nervous system

After injection of tritiated amino acid into the mouse eye, radioactivity appeared in the contralateral visual cortex, indicating that some material had been transferred from optic axons to lateral geniculate neurons. The radioactivity in the cortex was about 2 percent of that arriving in the geniculate, and most of it was contained in material that appeared to be protein.     

Habituation and dishabituation in the absence of a central nervous system

Habituation and dishabituation have been observed in a semi-intact Aplysia preparation in which the central nervous system is removed. The amplitude of withdrawal responses in the gill decreases in proportion to the rate of water drops applied (one drop per 0.5 minute to one drop per 2.5 minutes at 15 degrees C). The effects of habituation last for at least 2 hours. A dishabituated response is elicited by stopping the water drops or electrically stimulating the preparation. Furthermore, the gill contains nerve cell bodies, and habituation and dishabituation appear to be properties of these peripheral neurons.     

Illusory correlation of brightness enhancement and transients in the nervous system

Short light flashes can appear brighter than longer flashes. This brightness enhancement has often been attributed to neural transients occurring shortly after stimulus onset. This attribution assumes an equivalence between the totality of the response to a stimulus of a given duration and the instantaneous response at a given time after stimulus onset. Recordings from Limulus photoreceptors indicate that this attribution is an example of illusory correlation.     

Excitatory and inhibitory motoneurons in the central nervous system of the leech

The locomotion and reflex responses of the leech are brought about by inmuscles that are arranged in a regular, simple pattern in the body wall and that flatten, shorten, lengthen, or bend the animal. In the segmental ganglia, it is possible to recognize by morphological and physiological criteria the individual motoneurons that cause contractions and relaxations of these muscles.     

Sympathetic nervous control of cerebrospinal fluid production from the choroid plexus

The rabbit choroid plexus, responsible for the bulk production of cerebrospinal fluid, is well supplied by sympathetic nerves emanating in the superior cervical ganglia. Electrical stimulation of these nerves markedly reduces production of cerebrospinal fluid, measured by [14C] inulin dilution during ventricular perfusion, whereas sympathetic denervation enhances the rate of formation.