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At least 19 recordsLinked to original sources
PubMed1977

APUD cells and the apudomas. A concept relevant to anaesthesia and endocrinology.

A variety of cells found in the pituitary and pineal glands, sympathetic nervous system and adrenal glands, the gut, pancreas, thyroid (C-cells), chemoreceptors (type I-Cells), lungs (P-cells), skin (melanocytes) and the urogenital tract have a common origin from the neural crest. These cells are programmed for neuro-endocrine function and, as a group, can be regarded as one of the physiological control systems. They secrete a variety of amine and peptide hormones and have common cytochemical characteristics from which the term APUD cell is derived. Tumours of these cells are referred to as 'apudomas' and may synthesise not only their own hormones but also those which are normally produced by other APUD cells. The relevant physiological properties of some of the peptides which have been described relatively recently are discussed and the principal clinical syndromes produced by the APUDomas are described.

APUD Cells↗
PubMed1975

The ultrastructure of the sensory cells in the chemoreceptor of the ommatophore of Helix pomatia L.

Most of the sensory cells found in the chemoreceptor of the ommatophore of Helix pomatia are typical bipolar cells. The chemoreceptor is deveded by a furrow into two parts; within the ventral subdivision the layer of sensory cell bodiesis thicker than in the dorsal part. According to the differentiations of the apical surface of the dendrites, it is possible to distinguish six different classes: a) dendrites with one cilium and 75 nm thick cytofila (sometimes dendrites of identical appearance posses more than one cilium); b)dendrites with several cilial and 150 nm thick cytofila; c) dendrites with several cilia, 50 nm thick cytofila, and long, striated rootlets; d) dendrites with several cilia bur without cytofila; e) dendrites with 130 nm thick cytofila but without cilia; and f) dendrites with 65 nm thick cytofila but without cilia; dendrites of this class are the only ones with a cytoplasm more electron dense than that of the surrounding supporting cells. All these dendrites are connected to the surrounding supporting cells by terminal bars, each consisting of zonula adhaerens, aonula intermedia and zonula septata. The perikarya of the sensory cells measure approximately 15 mum by 8 mum and enclose 10 mum by 6 mum large nuclei. Axons, originating from these perikarya, extend to the branches of the digital ganglion. In the distal part of this gangloin the axons come into synaptic contact with interneurons, but in our electron micrography it was not possible to coordinate processes and synapses with the corresponding neurons.

Axons↗
PubMed1977

Response of avian intrapulmonary chemoreceptors to venous CO2 and ventilatory gas flow.

Avian intrapulmonary chemoreceptor activity is reduced by increasing airway PCO2 from 0 to 60 torr. Using extracellular electrodes, we recorded discharge of individual intrapulmonary chemoreceptor cell bodies in the left nodose ganglion of the rooster (Gallus domesticus) during unidirectional ventilation of the lungs. All receptors recorded were in the left lung. To vary pulmonary arterial PCO2 independently of ventilation, we ventilated the two lungs separately and supplied the left pulmonary circulation with systemic arterial blood. When the PCO2 in the pulmonary arterial blood was increased, discharge frequency decreased in all 21 receptors studied. Sensitivity to pulmonary arterial PCO2 was similar to sensitivity to airway PCO2. When PCO2 of ventilatory gas was lower than that of pulmonary arterial blood, discharge frequency of the receptor increased when pulmonary blood flow was stopped. Discharge frequency also increased when PCO2 at the receptor site was lowered by increased ventilatory gas flow. We conclude that intrapulmonary chemoreceptors respond to the delivery and removal of CO2 by blood and ventilatory gas. This suggests that the receptors are located within the respiratory gas exchange region of the lung. Because these receptors have a strong inhibitory effect on ventilation, they may serve to (1) adjust minute ventilation to the rate of metabolic CO2 production and (2) to regulate individual breath size.

Animals↗
PubMed1976

[Chemodectomas of the vagus nerve. Pathogenic hypothesis based on a review of 100 cases].

In connection with a personal case, 100 chemodectomas of the vagus described in the literature have been collected: revealing themselves in 75p. 100 of the cases in the form of cervical and pharyngeal tumours, 50p. 100 of the tumours of the vagal glomus involve some neurological manifestations mainly in the form of lesion of the lower cranial nerves. These appear to be either affected in isolation (41 p. 100) or in a dissociated manner (59 p. 100). Intra-cranial extension is rare (7 p. 100 of the cases) and delayed. Carotid angiography is characteristic. 76 p 100 are intra-vagal, 24 p. 100 are para-vagal and 60 p. 100 are located in the plexiform ganglion. Multifocal forms which account for 17 p. 100 of the cases are more usually, but not exclusively, familial. Surgical treatment is followed by sequelae or complications in more than half the cases. Close attention has been paid to pathogenetic theories: chemodectomas of the vagus may develop from type I chemoreceptor cells of the carotid glomera or from distinct cells with different properties (S.I.F. cells). They may equally well develop from nonchromaffin paraganglionic cells which have not migrated in the normal manner. The finding of such cells in the nerves of new-born babies and adults supports this theory, at least for some chemodectomas of the vagus.

Female↗
PubMed1975

Localization of acetylcholinesterase in granule-containing cells of glomus-like bodies in pre- and postnatal rabbits by electron microscopy.

The distribution of acetylcholinesterase (ACHE) was studied in the granule-containing cells which constitute the glomus-like bodies found near the origin of the great vessels in pre- and postnatal rabbits. Karnovsky's method for localization of ACHE at the electron-microscope level was used and suitable controls were carried out. In the granule-containing cells, ACHE reaction product was evident in the perinuclear cisternae and cisternae of the rough endoplasmic reticulum as well as at the cell membrane. ACHE activity was also localized at the axolemma of unmyelinated axons found near the granule-containing cells and around afferent synaptic terminals to these cells. Possible functions of ACHE associated with the monoamine-storing granule-containing cells are presented.

Acetylcholinesterase↗
PubMed1977

A response regulator model in a simple sensory system.

Bacterial behavior is shown to be modulated through a simple on-off switching device which directs migration toward favorable conditions and away from unfavorable ones. The behavioral response is controlled by a rudimentary memory which allows the bacteria to sense gradients over time. The memory can be explained by a biochemical system involving a response regulator whose level relative to a threshold controls flagellar function. The level of the response regulator is itself controlled by factors such as enzyme levels and environmental stimuli. The molecular basis of the model appears to be relevant to more complex hormonal and neural signaling systems.

Adaptation, Physiological↗
PubMed1975

Chemotaxis in bacteria.

Bacteria swim by rotating their flagella. They alter course by abruptly changing the direction of this rotation. The probability of the occurrence of this event is biased by chemoreception. The bias depends on the way in which the concentration of the attractant or repellent changes with time. Sugars are detected as they bind to specific proteins which also play a role in transport. The way in which the receptors are coupled to the flagella is not known. The coupling may involve changes in membrane potential.

Amino Acids↗
PubMed1976

The receptive mechanism of various metallic ions in the lateral-line organ of the tadpoles of Rana catesbeiana.

The stimulating effect on the receptor organ of various mono-and divalent metallic ions on the lateral-line nerve of tadpoles was studied. The orders of the effectiveness were Ag + greater than T1+ greater than K+==Na+ greater than Li for monovalent ions and Sr2+ greater than Mg2+ greater than or equal too Ba2+ greater than Cd2+ greater than or equal too Co2+ greater than Mn2+ greater than Zn2+ for divalent ions. Both agree well with the order of Pearson's softness parameter for monovalent ions and Edwards' modified parameter for divalent ones. All sorts of divalent cations exhibited suppressive effects on the stimulating effect of the monovalent cations when they were applied together with the monovalent cations. A simple selection rule was found for the suppressive effect. The stimulating effect of Na+ or K+ was suppressed by all sorts of divalent cations. But the effect of Ag+ was suppressed by Cd2+, but not by Mg2+ nor by Ca2+. In order to remove the Ag+ effect, a dilute solution of DTT was used, although the effect of K+ or Na+ was removed easily by rinsing with distilled water. From these results the receptive mechanism of the endorgan was thought to be chemical adsorption of ions in the receptor cell membrane. Based on the principle of "hard and soft acid and base", it is suggested that there are two types of binding sites for the ions on the membrane, a soft site and a hard one.

Action Potentials↗
PubMed1979

APUD-type recepto-secretory cells in the chicken lung.

The epithelium of the intrapulmonary airways of the chicken lung has been studied by fluorescence and electron microscopy. Numerous intensely yellow-fluorescent cells occur in the epithelium of the primary and secondary bronchi. The cell cytoplasm contains characteristic granular vesicles with an electron-dense central core. The vesicles react positively to chromaffin and argentaffin treatment, indicating that they are possible storage sites for amines. Synapse-like junctions occur between the granular cells and the intraepithelial nerve endings, filled with numerous mitochondria, suggesting that these granular cells may have a dual function as both receptor and endocrine cell.

APUD Cells↗