Modification of the Motor Reflex Responses Due to Repetition of the Peripheral Stimulus in the Cockroach

1973 ◽  
Vol 59 (2) ◽  
pp. 383-403
Author(s):  
N. F. ZILBER-GACHELIN ◽  
M. P. CHARTIER
Keyword(s):  
Motor Nerve ◽  
Spatial Summation ◽  
Minor Role ◽  
Peripheral Stimulus ◽  
Rhythmic Movements ◽  
Motor Responses ◽  
Escape Reflex ◽  
Motor Reflex ◽  
Time Courses ◽  
A Minor

1. The synaptic transfer properties within the 3rd thoracic ganglion (T.G.) from the abdominal cord axons to the motoneurones has been studied in the cockroach. This ganglion was completely de-afferented except for motor nerve 4, whose links with the muscles of the posterior legs were left intact. 2. The response of one of these nerves to electrical stimulation of the abdominal cord involves activation of 2 types of units: (a) Slow excitatory fibres which have a tonic discharge and respond to each lowthreshold abdominal cord stimulation by a transient increase of this firing rate; these units are responsible for muscular tonus and for low amplitude movements (startle reactions). (b) Fast excitatory fibres, which have no tonic discharge and require for their activation higher intensity and frequency of stimulation, i.e. an important temporal and spatial summation. They are responsible for larger and more rapid movements. They fire without any precise chronological relation with the stimuli, often in bursts which continue after the end of the stimulations and cause sudden rhythmic movements. 3. During repetition of the stimuli, the two types of synaptic pathways show both habituation and facilitation through temporal summation and post-tetanic potentiation. These two phenomena persist after the end of the stimulations and have long (minutes) but different time courses. Moreover, habituation always prevails over facilitation if stimulations are continued during a sufficient time. These antagonistic properties existing at the same time might explain the complex way in which the motor responses develop with the application of repetitive trains of stimuli to the cord. 4. The role of these properties in the changes of the reflex motor responses to successive air puffs applied to the cerci has been studied. These properties appear to be responsible for the sensitization of the responses which can be sometimes observed. They lead, in conjunction with the habituation properties of the 6th abdominal ganglion (A.G.), to the disappearance of the escape reflex involving firing of both fast and slow fibres. Finally, they seem to have a minor role in habituation of the startle reactions (involving firing of only the slow fibres) which would be mainly due to the 6th A.G. habituability.

Modification of the Motor Reflex Responses Due to Repetition of the Peripheral Stimulus in the Cockroach

1973 ◽  
Vol 59 (2) ◽  
pp. 359-381
Author(s):  
N. F. ZILBER-GACHELIN ◽  
M. P. CHARTIER
Keyword(s):  
Electrical Stimulation ◽  
Peripheral Stimulus ◽  
Excitatory Synapses ◽  
Nerve Response ◽  
Receptor Adaptation ◽  
Escape Reflex ◽  
Motor Reflex ◽  
Habituation Process ◽  
Transfer Properties ◽  
Stimulation Of

1. In the cockroach Blabera cranüfer repeated air puffs to the cerci induce a habituation of the corresponding escape reflex, which we have tried to relate to the transfer properties of the two central relays of the reflex. In this paper transmission through the first relay, the 6th abdominal ganglion (A.G.), was studied both by electrical stimulation of the sensory cereal nerve and by application of natural stimuli (air puffs) on the cerci, while recording simultaneously on the cereal nerve and the abdominal cord, i.e. respectively before and beyond the synaptic relay. 2. The electrical stimulation study shows transmission to be relatively labile. This property is still more apparent if air puffs are delivered. If they are separated by less than about 10 sec the cereal nerve response decreases, which is a sign of a receptor adaptation. For longer intervals, although this adaptation disappears, the response nevertheless decreases on the cord, implicating the ganglionic relay as the centre of a habituation phenomenon. 3. The characteristics of this habituation are the following: with repetition of the stimuli, the response decreases down to a non-zero plateau (decrease of about 50% if a puff is delivered every 20 sec); it recovers spontaneously if stimulations are suppressed ; habituation is potentiated when successive series of habituations followed by spontaneous restorations are accumulated; it is more pronounced as the stimulation frequency is increased; finally, it does not show generalization. These results confirm that the 6th A.G. independently exhibits a real habituation process. 4. The mechanism of this habituation process is discussed. A post-excitatory presynaptic depression intrinsic to the reflex's excitatory synapses themselves is tentatively proposed.

[Ca2+]ihomeostasis and cyclic nucleotide relaxation in aorta of phospholamban-deficient mice

1999 ◽  
Vol 277 (3) ◽  
pp. H963-H970 ◽  
Author(s):  
M. Jane Lalli ◽  
Shunichi Shimizu ◽  
Roy L. Sutliff ◽  
Evangelia G. Kranias ◽  
Richard J. Paul
Keyword(s):  
Steady State ◽  
Cyclic Nucleotide ◽  
Minor Role ◽  
Wild Type ◽  
Intact Mouse ◽  
In The Wild ◽  
Time Courses ◽  
A Minor ◽  
Mouse Aorta

Phospholamban (PLB), a protein localized in the sarcoplasmic reticulum (SR), inhibits the SR Ca2+-ATPase; phosphorylation of PLB relieves this inhibition. We previously reported significant differences in contractility in aorta from mice in which the gene for PLB was ablated (PLB−). In this study, we measured intracellular Ca2+concentration ([Ca2+]i) with fura 2 in the intact mouse aorta to more directly test the hypothesis that these changes are ascribable to altered SR function in vivo. Ten micromoles per liter of the α-agonist phenylephrine (PE) increased [Ca2+]imonotonically to a steady state in the wild-type aorta. In contrast, in PLB− aorta there was an initial rapid increase to a peak [Ca2+]i, which then decreased to a steady state that was lower than that in the wild type. Upon removal of the stimulus (either PE or KCl), the decrease in [Ca2+]iwas two times as fast in the PLB− as in the wild-type aorta. There were no significant differences between PLB− and wild-type aortas in the concentration vs. force relations or the time courses of relaxation in response to forskolin or sodium nitroprusside. Interestingly, stimulation of the cAMP pathway before cGMP pathway activation resulted in a significant increase in sensitivity and a difference in relaxation parameters between PLB− and wild-type aortas. Western blot analysis indicated that the PLB-to-sarcoendoplasmic reticulum Ca2+ATPase ratio in the mouse aorta was similar to that in the heart; 20-fold more aortic than heart homogenate was required to achieve a similar level of immunoreactivity. Our data indicate that PLB can play a major role in modulating smooth muscle [Ca2+]ibut only a minor role, if any, in cyclic nucleotide-mediated relaxation.

Changes of sympathetic nerve activity induced by 2-deoxy-D-glucose infusion in humans

1989 ◽  
Vol 256 (6) ◽  
pp. E714-E720 ◽  
Author(s):  
J. Fagius ◽  
C. Berne
Keyword(s):  
Sympathetic Activity ◽  
Blood Levels ◽  
Minor Role ◽  
Base Line ◽  
Glucose Levels ◽  
Muscle Nerve ◽  
Sudomotor Activity ◽  
Time Courses ◽  
A Minor ◽  
Line Level

Microelectrode recording of sympathetic signals in the peroneal nerve was performed in 14 healthy volunteers following infusion of 2-deoxy-D-glucose (50 ml/kg body wt). Heart rate, blood pressure, body temperature, hematocrit, and blood levels of glucose, insulin, and catecholamines were monitored. Muscle nerve sympathetic activity (MSA), which is involved in cardiovascular homeostasis, increased significantly from a base-line level of 19.9 +/- 4.5 (mean +/- SE) bursts/min to a peak 30 min after the start of the infusion of 33.1 +/- 5.1 bursts/min. Skin nerve sympathetic activity (SSA), which is a mixture of sudomotor and vasoconstrictor signals, also increased to a peak at 30 min. The impulse pattern of SSA suggested that the increase involved mainly sudomotor activity, with simultaneous inhibition of vasoconstrictor signals. The time courses of MSA and the circulatory responses suggested that the increase in MSA was not a baroreceptor-induced counteraction of the cardiovascular changes during glucopenia. The responses of MSA and SSA were remarkably similar to those observed previously during insulin-induced hypoglycemia. The relationship between changes of sympathetic outflow, glucose levels, and insulin levels in the present study indicates that the effects observed are consequences of central nervous system glucopenia, with insulin playing a minor role. It is concluded that the sympathoadrenal system responds in a markedly differentiated way to glucopenia.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Produktivkraft als Versprechen

2016 ◽  
Vol 46 (185) ◽  
pp. 621-638 ◽  
Author(s):  
Christian Siefkes
Keyword(s):  
Private Consumption ◽  
Minor Role ◽  
Progressive Reduction ◽  
Internal Forces ◽  
A Minor

The ‘Fragment on Machines’ from Marx’s Grundrisse is often cited as an argument that the internal forces of capitalism will lead to its doom. But the argument that the progressive reduction of labor must doom capitalism lacks a proper foundation, as a comparison with the ‘Schemes of Reproduction’ given in Capital II shows. The latter, however, aren’t fully convincing either. In reality, more depends on the private consumption of capitalists than either model recognizes. Ultimately, most can be made of the ‘Fragment on Machines’ by reading it not as an exposure of capitalism’s internal contractions, but as a discussion of a possible communist future where labor (or work) will play but a minor role.

Effects of Myo-inositol Alone and in Combination with Seleno-Lmethionine on Cadmium-Induced Testicular Damage in Mice

2019 ◽  
Vol 12 (4) ◽  
pp. 311-323 ◽  
Author(s):  
Salvatore Benvenga ◽  
Antonio Micali ◽  
Giovanni Pallio ◽  
Roberto Vita ◽  
Consuelo Malta ◽  
...  
Keyword(s):  
Structural Changes ◽  
Natural Antioxidants ◽  
Minor Role ◽  
Positive Role ◽  
Testosterone Levels ◽  
Tnf Α ◽  
Testicular Lesions ◽  
A Minor ◽  
Immunohistochemical Analyses

Background: Cadmium (Cd) impairs gametogenesis and damages the blood-testis barrier. Objective: As the primary mechanism of Cd-induced damage is oxidative stress, the effects of two natural antioxidants, myo-inositol (MI) and seleno-L-methionine (Se), were evaluated in mice testes. Methods: Eighty-four male C57 BL/6J mice were divided into twelve groups: 0.9% NaCl (vehicle; 1 ml/kg/day i.p.); Se (0.2 mg/kg/day per os); Se (0.4 mg/kg/day per os); MI (360 mg/kg/day per os); MI plus Se (0.2 mg/kg/day); MI plus Se (0.4 mg/kg/day); CdCl2 (2 mg/kg/day i.p.) plus vehicle; CdCl2 plus MI; CdCl2 plus Se (0.2 mg/kg/day); CdCl2 plus Se (0.4 mg/kg/day); CdCl2 plus MI plus Se (0.2 mg/kg/day); and CdCl2 plus MI plus Se (0.4 mg/kg/day). After 14 days, testes were processed for biochemical, structural and immunohistochemical analyses. Results: CdCl2 increased iNOS and TNF-α expression and Malondialdehyde (MDA) levels, lowered glutathione (GSH) and testosterone, induced testicular lesions, and almost eliminated claudin-11 immunoreactivity. Se administration at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression, maintained GSH, MDA and testosterone levels, structural changes and low claudin-11 immunoreactivity. MI alone or associated with Se at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression and MDA levels, increased GSH and testosterone levels, ameliorated structural organization and increased claudin-11 patches number. Conclusion: We demonstrated a protective effect of MI, a minor role of Se and an evident positive role of the association between MI and Se on Cd-induced damages of the testis. MI alone or associated with Se might protect testes in subjects exposed to toxicants, at least to those with behavior similar to Cd.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

scholarly journals The preendosomal compartment comprises distinct coated and noncoated endocytic vesicle populations.

1991 ◽  
Vol 113 (4) ◽  
pp. 731-741 ◽  
Author(s):  
S H Hansen ◽  
K Sandvig ◽  
B van Deurs
Keyword(s):  
Cell Surface ◽  
Coated Vesicles ◽  
Minor Role ◽  
Specific Marker ◽  
Con A ◽  
Early Endosomes ◽  
Gold Conjugate ◽  
Entire Cell ◽  
A Minor ◽  
Endocytic Vesicles

The transfer of molecules from the cell surface to the early endosomes is mediated by preendosomal vesicles. These vesicles, which have pinched off completely from the plasma membrane but not yet fused with endosomes, form the earliest compartment along the endocytic route. Using a new assay to distinguish between free and cell surface connected vesicle profiles, we have characterized the preedosomal compartment ultrastructurally. Our basic experimental setup was labeling of the entire cell surface at 4 degrees C with Con A-gold, warming of the cells to 37 degrees C to allow endocytosis, followed by replacing incubation medium with fixative, all within either 30 or 60 s. Then the fixed cells were incubated with anti-Con A-HRP to distinguish truly free (gold labeled) endocytic vesicles from surface-connected structures. Finally, analysis of thin (20-30 nm) serial sections and quantification of vesicle diameters were carried out. Based on this approach it is shown that the preendosomal compartment comprises both clathrin-coated and non-coated endocytic vesicles with approximately the same frequency but with distinct diameter distributions, the average noncoated vesicle being smaller (95 nm) than the average coated one (110 nm). In parallel experiments, using an anti-transferrin receptor gold-conjugate as a specific marker for clathrin-dependent endocytosis it is also shown that uncoating of coated vesicles plays only a minor role for the total frequency of noncoated vesicles. Furthermore, after perturbation of clathrin-dependent endocytosis by potassium depletion where uptake of transferrin is blocked, noncoated endocytic vesicles with Con A-gold, but not coated vesicles, exist already after 30 and 60 s. Finally, it is shown that the existence of small, free vesicles in the short-time experiments cannot be ascribed to recycling from the early endosomes.

scholarly journals Sun Protection and Sunburn in Children Aged 1–10 Years in Germany: Prevalence and Determinants

Children ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 668
Author(s):  
Tatiana Görig ◽  
Corinna Södel ◽  
Annette B. Pfahlberg ◽  
Olaf Gefeller ◽  
Eckhard W. Breitbart ◽  
...  
Keyword(s):  
Role Models ◽  
Skin Color ◽  
Role Model ◽  
Sun Protection ◽  
Minor Role ◽  
Positive Role ◽  
Protection Measures ◽  
Telephone Interviews ◽  
The Past ◽  
A Minor

Seeking shade, the use of textile sun protection and sunscreen, and protecting one’s eyes by wearing sunglasses are recommended sun protection measures in children. We aimed to quantify the use of these measures as well as the prevalence of sunburn in children aged 1 to 10 years in Germany and to identify their determinants. Data collected via telephone interviews in a nationwide sample of 554 parents or caregivers in family were analyzed. Use of sunscreen was the most common measure applied (77.8%), while sunglasses were least frequently used (12.5%). The prevalence of sunburn during the past year was 21.8%, and it was positively associated with children’s age. The use of sun protection measures was significantly associated with the age and skin color of the child, while characteristics and tanning behaviors of the caregivers only played a minor role. The use of sun protection measures was higher when caregivers perceived themselves as a role model (Odds Ratio (OR) = 4.33, p < 0.001). Our nationwide data show that there remains a need for the improved use of sun protection measures, especially in children aged 7 to 10 years. In educational material, parents should be encouraged to become positive role models for their children regarding sun protection.

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