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Biomedical subjects

A Wagner

Publications and source records attributed to A Wagner.

At least 487 records · Page 27Linked to original sources
PubMed1976

Degenerated boutons in the fundus striati (nucleus accumbens septi) after lesion of the parafascicular nucleus in the cat.

An attempt has been made to reveal which of the nine different types of synapses in the fundus striati, discriminated in a previous study, degenerate following experimental lesions in the parafasciculo-center median complex of the cat. Two types of synaptic contacts were found to be degenerated two days after the lesion was performed: (1) the axo-spinous type IV, characterized by densely-packed, small, round vesicles and a strong asymmetric thickening, and (2) the axo-dendritic or axo-somatic type VII, again characterized by small, round vesicles in a dense accumulation and an asymmetric thickening. After two days of survival the original characteristics of the boutons could still be recognized in both types of synapses. A positive correlation exists between the location and extent of the coagulation foci in the parafascicular nucleus and the appearance of degenerated boutons in the fundus striati. Therefore, the conclusion that the parafasciculofundus neurons terminate as type IV or type VII boutons is entirely justified. Additionally, the role of the special types of boutons in the synaptic organization of the fundus striati has been discussed.

Animals↗
PubMed1976

Some pharmacological properties of the false cholinergic transmitter acetylpyrrolidinecholine and its precursor pyrrolidinecholine.

The acetylchline analogue acetylpyrrolidinecholine as well as the choline analogue pyrrolidinecholine were synthesized and the cholinergic properties of both substances were investigated on the guinea-pig ileum, rat blood pressure and frog rectus abdominis muscle. Acetylpyrrolidinecholine was 3-5 times less potent than acetylcholine on the three preparations tested. The dose-response curves to acetylpyrrolidinecholine were shifted to the right in a parallel manner by atropine and (+)-tubocurarine. The dissociation constants for atropine and (+)-tubocurarine obtained with acetylpyrrolidinecholine as agonist were not different from those obtained with acetylcholine. This indicates that acetylpyrrolidinecholine specifically stimulates muscarine and nicotine receptors. Eserine potentiated the effects of acetylcholine more than those of acetylpyrrolidinecholine. Pyrrolidinecholine was only a weak agonist on the guinea-pig ileum. It caused a rise of rat blood pressure in doses higher than 10 mumol per rat. Neuromuscular transmission of the phrenic nerve-diaphragm preparation of the rat was not impaired during a 150 min incubation period with 1 mM pyrrolidinecholine. It is suggested that the possible formation and release of acetylpyrrolidinecholine as a false cholinergic transmitter does not modify neuromuscular transmission in skeletal muscle.

Acetylcholine↗
PubMed1976

The nigrostriatal projection in the cat. Part 1. Silver impregnation study.

The course and destination of the degenerating nigrostriatal fibers were studied by selective silver impregnation methods in 37 cats with unilateral lesions in the substantia nigra. The nigrostriatal fibers ascend along the dorsomedial border of the substantia nigra to the prerubral area; they proceed for a short distance through the lateral hypothalamus, enter the medial part of the internal capsule and run in a dorsorostral direction to reach the head of the caudate nucleus and the rostral portion of the putamen. A smaller number of degenerating fibers obliquely cross the peduncular part of the internal capsule and traverse the entopeduncular nucleus and the pallidum to terminate in the central and caudal portions of the putamen. Some features of the topical distribution of the nigrostriatal tract are described. Apparently, the more anterior part of the pars compacta sends axons primarily to the head of the caudate nucleus and to the most rostral putamen. The most medially situated nigral neurons project to the fundus striati. The posteromedial cell groups of the pars compacta innervate primarily the central putamen and the caudal part of the caudate nucleus. The projection of the lateral cell group of the posterior zona compacta to the caudal putamen is sparser than from the other nigral groups, suggesting that a part of them has another destination, possibly lower in the neuraxis. The contribution of the pars of reticulata to the nigrostriatal connections seems to be modest, according to the small number of neurons; they project to the lateral caudate and putamen. Thus, the ascending nigrostriatal fibers mirror the distribution of the descending striatonigral fibers. No convincing evidence for the existence of a nigroentopeduncular and nigropallidal projection was found.

Animals↗
PubMed1976

Effects of ethosuximide upon psychomotor responses and electromyographic parameters of healthy individuals.

The purpose of this paper was to investigate the effects of anticonvulsant ethosuximide upon physiological parameters, psychomotor reactions and electromyographic criteria. Ethosuximide increased the reaction times to flashes and the choice reaction time in most subjects, often provoked a greater amount of errors during choice reactions and decreased the average heart frequency. The functional activation during the tasks was diminished. The EEG showed no marked qualitative or quantitative changes. Ethosuximide reduced the maximum conduction velocity of the motor nerve and changed the action potential duration but not the action potential shape. There is no exact parallelism between the increase in reaction time and decrease of nerve conduction velocity. The drug effect upon psychomotor reactions seems to be caused by reduction of vigilance and an inhibitory effect upon the individual's motor responsiveness. Like other anticonvulsants, ethosuximide may alter the electrical properties of all excitable membranes and, by this ubiquitous site of action, exerts the described effects.

Action Potentials↗
PubMed1976

[Changes depend on age in electromyogram -- studies about parameter of motor unit action potentials in normal subjects of different age (author's transl)].

In normal subjects of different age groups electromyographically several muscles were examined. The motor unit action potentials were registered and parameters of those were evaluated manually and digitally. For all examined muscles was found an increase in the duration of potentials with the age. The increase was greatest in the younger and older age groups. An interpretation of these findings is given.

Action Potentials↗
PubMed1975

[Congenital aplastic anemia, type I].

Case report of a 7 year old girl, anaemic since birth. The anaemia, of variable intensity, is associated with a moderate reticulocytosis. Bone marrow films, show a marked erythroblastosis with conspicuous morphological abnormalities and internuclear chromatin bridges. The erythrocinetic pattern is that of ineffective erythropoiesis. The morphologic features are those of Heimpel and Wendt's type I congenital dyserythropoiesis. The erythrocytes are lysed by some acidified sera, thus showing a membrane anomaly which is unusual in type I. However the characteristics of the lysis are different from those of type II (HEMPAS) erythrocytes.

Anemia, Macrocytic↗
PubMed1975

[Double-barrelled connections between the striatum and substantia nigra in the light and electron microscopy picture in the cat].

Following coagulation of either the substantia nigra or the caudate nucleus and fundus caudati of the cat, the distribution of degenerating terminals in the sections of the striatum has been determined especially in the fundus caudati on one side and in the various cell groups of the substantia nigra compacta on the other side; and the types of synapses have been described. There are reverberating circuits between the fundus caudati and the medial groups of the nigra characterized by their small cells, between the putamen and the postero-lateral cell groups of the nigra, between the caudatum and the rostral cell groups of the nigra, presumably with the specialization that the lateral caudatum is in two-way connection with the rostro-lateral cell groups of the nigra as is the medial caudatum with the rostro-medial cell group. The transmitter for the striatofugal terminals in the nigra which have pleomorphic synapses is probably GABA. Dopamine is the transmitter of the axo-spinous synapses of the nigrostriatal neurons with the small striatal nerve cells for which the transmitter seems to be Acetylcholine. The nigro-striatal reverberating circuits have three outputs available; 1. from parts of the striatum to the entopeduncular nucleus (internal segment of pallidum) and from there through the H2 and H1 fields of Forel to the oral ventral nucleus of the thalamus (V.o.a) which directly projects to the area 6 a alpha of motor cortex; 2. also from parts of the striatum to the pallidum (outer segment) and continuing through the descending pallido-reticulospinal pathway and 3. from the postero-lateral cell groups of the nigra probably through descending fibers which cross the midline in the commissura colliculi superioris and extend through the reticular formation directly or indirectly to the spinal cord.

Animals↗
PubMed1975

[Parameters of digitally averaged potentials of individual motor units].

Of sixty normal subjects of different age six different muscles each were examined electromyographically. The activity pattern was recorded for moderate voluntary innervation and superposed digitally. The parameters of digitally averaged summation action potentials were compared with those of manually assessed potentials. The two methods gave identical results: The duration of potentials was between 5 and 10 ms. It increased in the younger and older age groups and showed only slight changes in middle-aged persons. Only minor differences were found between the muscles of one age group, an exception being the orbicularis oris muscle. The results obtained are compared with values reported in the literature.

Action Potentials↗