Imaging of population spikes induced by repetitive stimulus pulses in mouse cerebral slices in vitro

2017 ◽  
Author(s):  
Tomohiro Nomoto ◽  
Yuta Tanaka ◽  
Yuki Hayashida ◽  
Tetsuya Yagi
Keyword(s):  
Population Spikes ◽  
Repetitive Stimulus

Etomidate Does Not Alter Recovery after Anoxia of Evoked Population Spikes Recorded from the CA1 Region of Rat Hippocampal Slices 

1998 ◽  
Vol 88 (5) ◽  
pp. 1274-1280 ◽  
Author(s):  
Eduarda M. Amadeu ◽  
Elisabeth A. Abramowicz ◽  
Geoffrey Chambers ◽  
James E. Cottrell ◽  
Ira S. Kass
Keyword(s):  
Propylene Glycol ◽  
Adenosine Triphosphate ◽  
Hippocampal Slices ◽  
Population Spike ◽  
High Concentration ◽  
Population Spikes ◽  
Ca1 Region ◽  
Cardiovascular Depression ◽  
Collateral Pathway

Background Etomidate is an anesthetic agent that reduces the cerebral metabolic rate and causes minimal cardiovascular depression. Its ability to improve recovery after anoxia or ischemia is equivocal. An in vitro neuronal preparation was used to examine the action of etomidate on electrophysiologic and biochemical parameters during and after anoxia. Methods The Schaffer collateral pathway was stimulated, and a postsynaptic evoked population spike was recorded from the CA1 pyramidal cell layer of rat hippocampal slices. Etomidate or propylene glycol, its solvent, was present 15 min before, during, and 10 min after anoxia. Adenosine triphosphate, sodium, and potassium concentrations were measured at the end of anoxia in tissue treated with etomidate, propylene glycol, or with no added drugs. Results Etomidate did not alter recovery after 6 min of anoxia. The population spikes from untreated slices recovered to 32% of their preanoxic amplitude, and slices treated with 0.5, 3, and 30 microg/ml etomidate recovered to 24%, 35%, and 13%, respectively. Slices treated with propylene glycol, equivalent to that in 3 and 30 microg/ml etomidate, recovered to 46% and 12%, respectively, and this was not significantly different from untreated slices. Etomidate did not attenuate the decrease in adenosine triphosphate concentrations during anoxia. The increase in sodium and the decrease in potassium during anoxia were significantly attenuated by 30 but not by 3 microg/ml etomidate. Conclusions A range of etomidate concentrations did not significantly alter recovery of the evoked population spike after anoxia in rat hippocampal slices. A high concentration of etomidate did attenuate the increase in sodium and the decrease in potassium during anoxia.

Sustained potential shifts and paroxysmal discharges in hippocampal formation

1985 ◽  
Vol 53 (4) ◽  
pp. 1079-1097 ◽  
Author(s):  
G. G. Somjen ◽  
P. G. Aitken ◽  
J. L. Giacchino ◽  
J. O. McNamara
Keyword(s):  
Action Potentials ◽  
Hippocampal Formation ◽  
Repetitive Stimulation ◽  
Tissue Slices ◽  
Fascia Dentata ◽  
Population Spikes ◽  
Anesthetized Rats ◽  
Freely Moving ◽  
Stimulation Of

Paroxysmal firing was provoked by electric stimulation of afferent pathways in hippocampal formation of intact, urethan-anesthetized rats, of freely moving unanesthetized rats, and in hippocampal tissue slices in vitro. The electric responses of fascia dentata and CA3 zone of the hippocampus of urethan-anesthetized rats were recorded with extracellular microelectrodes. Paroxysmal discharges were provoked by stimulating the ipsilateral angular bundle. During repetitive stimulation, intercurrent paroxysmal discharges (IPaD) took the form of compound action potentials (population spikes) of large amplitude, provoked by but not locked in time to the stimulus pulses. IPaD was often but not always followed by paroxysmal after-discharge (PaAD), usually consisting of bursts of population spikes, sometimes superimposed on a slow wave. Stimulus pulses that were not strong enough to evoke population spikes when applied singly could provoke the paroxysmal firing of large amplitude spikes when applied repetitively. The liminal frequency to provoke paroxysmal firing, with 10-s train duration and with pulses evoking 60 to 80% of maximal amplitude focal postsynaptic potential (PSP) waves, varied between 6 and 15 Hz in urethan-anesthetized rats. The outbreak of IPaD was always accompanied by a marked sustained potential (SP) shift. The polarity of the paroxysmal SP shift was the opposite of the polarity of the PSP waves. We conclude that the extracellular paroxysmal SP shifts in fascia dentata are probably generated mainly by current flowing from the dendritic trees toward the cell somata of granule cells. The amplitude of the population spikes fired during paroxysmal discharges could reach 30-40 mV, indicating the precise coincidence of the impulses fired by many neurons. These spikes often arose without a detectable preceding synaptic potential. We conclude that the synchronization of the action potentials fired by granule and pyramidal cells during paroxysmal discharge is probably due to electric interaction among the neurons. In unanesthetized freely moving rats IPaD and PaAD consisting of bursts of population spikes were provoked. These were similar to those observed in urethan-anesthetized rats. Motor seizures provoked in kindled rats were associated with intense and prolonged spike bursts followed by spikeless positive waves recorded in the granule cell layer of fascia dentata. In hippocampal tissue slices maintained in vitro, paroxysmal firing could be provoked in CA1 zone by repetitive stimulation of Schaffer collaterals. IPaD and PaAD could be provoked in some slices exposed to normal (3.5 mM) [K+] and in all slices exposed to elevated (5.5 or 7.0 mM) [K+].(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

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