Pharmacological Induction of Plasticization in the Abdominal Cuticle of Rhodnius

1974 ◽  
Vol 61 (3) ◽  
pp. 705-718
Author(s):  
STUART E. REYNOLDS

Injections of 5-hydroxytryptamine (5-HT, serotonin) are found to cause plasticization of the abdominal cuticle of Rhodnius larvae. This plasticization is a direct action of 5-HT on some element in the body wall; the central nervous system is not required. It is probable that 5-HT acts directly at a receptor on the epidermal cells. The relationship between structure and plasticizing activity for a number of 5-HT analogues has been investigated. The receptor resembles other ‘classical’ 5-HT receptors in its requirements, but is unlike the 5-HT/diuretic hormone receptor of Rhodnius Malpighian tubules.

1937 ◽  
Vol 14 (3) ◽  
pp. 290-301
Author(s):  
G. P. WELLS

1. The gut of Glycera consists of (a) the buccal tube, (b) the pharynx, containing the jaws with their associated muscles and glands and the principal stomatogastric ganglia, (c) the oesophagus, leading from the pharynx to (d) the intestine, in which digestion occurs. 2. An "isolated extrovert" preparation is described, consisting of the buccal tube, pharynx and oesophagus. The movements of the buccal tube and oesophagus are recorded separately. The preparation has the following properties: (a) The buccal tube shows vigorous, rapid contractions with a somewhat irregular rhythm. These contractions are due to impulses coming forwards from the pharynx, the buccal tube itself having little power of spontaneous movement. (b) The oesophagus shows tone-waves, on which more rapid contractions of small amplitude may be superposed. These contractions and tone-waves are due to impulses originating in the wall of the oesophagus itself. (c) In a few preparations only, synchronous movements of buccal tube and oesophagus were seen. The site of origin of this synchronous activity was not determined. 3. An "extrovert-body wall" preparation is described, in which the movements of the body wall and buccal tube are separately recorded while the normal nervous conduction paths between them remain intact. The preparation has the following properties: (a) In most cases the body wall shows slight movements only, and the buccal tube moves little or not at all. If, however, the buccal tube be cut across close to the mouth, it begins an irregular rhythm of vigorous contractions, due to impulses originating in the pharynx, which usually continues without diminution for hours. The quiescence of the buccal tube before this cut is made indicates that the central nervous system normally exerts an inhibitory influence on the pharynx. (b) In a few preparations, correlated outbursts of contraction in the body wall and buccal tube were seen. These outbursts, which possibly correspond to extrusion movements of the intact worm, are due to impulses originating in the central nervous system. 4. The results are compared with those previously obtained on Arenicola marina, and reported in an earlier paper.


The alimentary canal of Lumbricus exhibits autonomous rhythmic movements, probably co-ordinated by nerve elements situated in its walls. The gut is subject to indirect control by extrinsic nerves which fall into two groups mutually antagonistic in their effects. Nerves which augment the tone of the gut muscles leave the central nervous system by the middle and posterior nerves of each segment and join nerve elements (apparently arranged as a plexus) situated in the peritoneum of the body wall, from which nerves pass to enter the gut by the ventro-lateral regions of each septum. Nerves which diminish the tone of the gut leave the central nervous system by the anterior, middle and posterior nerves of each segment and join nerve elements (also probably in the form of a plexus) situated in the muscular layer of the body wall, from which nerves arise to enter the gut via the dorso-lateral region of each septum. The alimentary canal receives another nerve supply from the peripharyngeal commissures of the central nervous system by means of a number of fine plexiform nerves partially embedded in the pharyngeal musculature of either side (pharyngeal plexus). The anatomical relationships of these nerves are described. The pharyngeal plexuses are shown to embody nerve elements which exert an indirect control over the gut, stimulation of these resulting in a fall in tone of all regions of the gut behind the pharynx. The nerve supply of the gut is compared with that which is known in other annelids, and the mechanism of indirect control is compared with that existing in vertebrates.


Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 329-343
Author(s):  
Par B. Boilly

Supernumerary tail and parapodia induction by deviation of the intestine in nereids (Annelida: Polychaeta) Localized ablation of the intestine has been performed on normal and grafted specimens of the two polychaetes Nereis pelagica L. and Perinereis cultrifera G. with the following results: (1) In the absence of the intestine, segments are not regenerated but parapodia grow on the plane of section. (2) A segmented tail arises where the intestine is deviated; the regenerate we obtain in this case is of the ‘aneurogenic’ type and without anal cirri and parapodia. (3) These results suggest that caudal regeneration results from the association of different tissues (intestine and the body wall) whereas the nerve cord exerts an influence upon the organization of the regenerate. Likewise the caudal regeneration of parapodia is the consequence of the juxtaposition of a dorsal and a ventral body wall in the presence of the central nervous system.


2020 ◽  
Vol 18 (1) ◽  
pp. 28-31
Author(s):  
Natalia Leksa ◽  
◽  
David Aebisher ◽  
Dorota Bartusik-Aebisher ◽  
◽  
...  

Introduction. Magnetic Resonance Imaging (MRI) has modified the practice of radiology. MRI is base on safe interaction between radiowaves at a particular frequency and hydrogen nuclei in the body. Metabolic encephalophaties are by definition those disorder of the central nervous system that are not due primarily to structural abnormalities. Aim. Here we present the 1H MRI and functional MRI (fMRI) method applied to diagnosis of disorders of the central nervous system. Material and methods. Analysis of literature and self-research. Results.We have discussed the major MRI applications in the characteristic of the central nervous system. The relationship beteen the motion of flowing blood and the representation of the blood on images is complex. This work is an introduction to the basic ideas and techniques of fMRI. Therefore, both, 1H MRI and functional MRI, methods are ued in neuroscience. Conclusion. Nonivasive MRI and functional MRI are daily diagnostics methods in neurology.


Author(s):  
F. L. Azizova ◽  
U. A. Boltaboev

The features of production factors established at the main workplaces of shoe production are considered. The materials on the results of the study of the functional state of the central nervous system of women workers of shoe production in the dynamics of the working day are presented. The level of functional state of the central nervous system was determined by the speed of visual and auditory-motor reactions, installed using the universal device chronoreflexometer. It was revealed that in the body of workers of shoe production there is an early development of inhibitory processes in the central nervous system, which is expressed in an increase in the number of errors when performing tasks on proofreading tables. It was found that the most pronounced shift s in auditory-motor responses were observed in professional groups, where higher levels of noise were registered in the workplace. The correlation analysis showed a close direct relationship between the growth of mistakes made in the market and the decrease in production. An increase in the time spent on the task indicates the occurrence and growth of production fatigue.Funding. The study had no funding.Conflict of interests. The authors declare no conflict of interests.


Author(s):  
Prithiv K R Kumar

Stem cells have the capacity to differentiate into any type of cell or organ. Stems cell originate from any part of the body, including the brain. Brain cells or rather neural stem cells have the capacitive advantage of differentiating into the central nervous system leading to the formation of neurons and glial cells. Neural stem cells should have a source by editing DNA, or by mixings chemical enzymes of iPSCs. By this method, a limitless number of neuron stem cells can be obtained. Increase in supply of NSCs help in repairing glial cells which in-turn heal the central nervous system. Generally, brain injuries cause motor and sensory deficits leading to stroke. With all trials from novel therapeutic methods to enhanced rehabilitation time, the economy and quality of life is suppressed. Only PSCs have proven effective for grafting cells into NSCs. Neurons derived from stem cells is the only challenge that limits in-vitro usage in the near future.


1984 ◽  
Vol 4 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Luigi F. Agnati ◽  
Kjell Fuxe

The hypothesis is introduced that miniaturization of neuronal circuits in the central nervous system and the hierarchical organization of the various levels, where information handling can take place, may be the key to understand the enormous capability of the human brain to store engrams as well as its astonishing capacity to reconstruct and organize engrams and thus to perform highly sophisticated integrations. The concept is also proposed that in order to understand the relationship between the structural and functional plasticity of the central nervous system it is necessary to postulate the existence of memory storage at the network level, at the local circuit level, at the synaptic level, at the membrane level, and finally at the molecular level. Thus, memory organization is similar to the hierarchical organization of the various levels, where information handling takes place in the nervous system. In addition, each higher level plays a role in the reconstruction and organization of the engrams stored at lower levels. Thus, the trace of the functionally stored memory (i.e. its reconstruction and organization at various levels of storage) will depend not only on the chemicophysical changes in the membranes of the local circuits but also on the organization of the local circuits themselves and their associated neuronal networks.


In the study of the phenomena of anaphylaxis there are certain points on which some measure of agreement seems to have been attained. In the case of anaphylaxis to soluble proteins, with which alone we are directly concerned in this paper, the majority of investigators probably accept the view that the condition is due to the formation of an antibody of the precipitin type. Concerning the method, however, by which the presence of this antibody causes the specific sensitiveness, the means by which its interaction with the antibody produces the anaphylactic shock, there is a wide divergence of conception. Two main currents of speculation can be discerned. One view, historically rather the earlier, and first put forward by Besredka (1) attributes the anaphylactic condition to the location of the antibody in the body cells. There is not complete unanimity among adherents of this view as to the nature of the antibody concerned, or as to the class of cells containing it which are primarily affected in the anaphylactic shock. Besredka (2) himself has apparently not accepted the identification of the anaphylactic antibody with a precipitin, but regards it as belonging to a special class (sensibilisine). He also regards the cells of the central nervous system as those primarily involved in the anaphylactic shock in the guinea-pig. Others, including one of us (3), have found no adequate reason for rejecting the strong evidence in favour of the precipitin nature of the anaphylactic antibody, produced by Doerr and Russ (4), Weil (5), and others, and have accepted and confirmed the description of the rapid anaphylactic death in the guinea-pig as due to a direct stimulation of the plain-muscle fibres surrounding the bronchioles, causing valve-like obstruction of the lumen, and leading to asphyxia, with the characteristic fixed distension of the lungs, as first described by Auer and Lewis (6), and almost simultaneously by Biedl and Kraus (7). But the fundamental conception of anaphylaxis as due to cellular location of an antibody, and of the reaction as due to the union of antigen and antibody taking place in the protoplasm, is common to a number of workers who thus differ on details.


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