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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↗
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↗
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↗
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↗
PubMed1979

Attractants and repellents influence methylation and demethylation of methyl-accepting chemotaxis proteins in an extract of Escherichia coli.

During bacterial chemotaxis, attractants and repellents alter the methylation levels of the methyl-accepting chemotaxis proteins (MCPs). These methylation levels represent a balance between two enzymatic processes: methylation and demethylation. In vivo experiments previously have shown that chemoeffectors influence the demethylation process; effects on the methylation system have not been reported. Here we show that in a cell-free extract of Escherichia coli both methylation and demethylation of the MCPs are affected by attractants and repellents. Attractants enhance methylation and inhibit demethylation. Repellents inhibit methylation and stimulate demethylation. The cell-free system provides an opportunity for further study of the mechanisms by which attractants and repellents influence the levels of methylation of the MCPs.

Bacterial Proteins↗
PubMed1978

The structure of teleost epidermis with special reference to new qualitative and quantitative data from the guppy, Poecilia reticulata Peters.

Scales from the midlateral body region of adult male guppies, Poecilia reticulata Peters, were investigated morphometrically by light and electron microscopy. The epidermis consists of one superficial layer and, in general, two basal layers of filament-containing cells and a number of mucous cells. There are scattered chemosensory cells and unmyelinated nerve fibres. Superficial cells are flattened and form apical ridges in a fingerprint-like arrangement. The volume density of mitochondria, granular endoplasmic reticulum, and numerical density of dictyosomes are higher in superficial cells than in basal cells. The superficial cells are secretorily active. Small electron dense vesicles are transported from the dictyosomes to the body surface and yield the glycocalyx material, which is not identical with the slime produced by the mucous cells.

Animals↗
PubMed1977

Analysis of intracellular recordings from salamander olfactory epithelium.

Intracellular recordings have been obtained from provisionally identified olfactory receptor and sustentacular cells in the salamander olfactory epithelium. Two categories of membrane potential transients were recorded intracellularly in response to odor stimulation. The first category of responses, presumably recorded from receptor cell somas, were monophasis positive spikes 10-50 mV in amplitude which were superimposed on a depolarizing slow potential which ranged from 4 to 8 mV in amplitude. Graded and differential responses were recorded in response to odor stimulation. The second category of responses were depolarizing and hyperpolarizing slow membrane potential transients presumably recorded from sustentacular cells. Spiking was not observed in response to odor stimulation. Pysiological criteria and Procion dye marking in several instances have provided evidence that responses in the first category were recorded from olfactory receptors and that certain of the other responses were recorded from sustentacular cells.

Ambystoma↗
PubMed1978

Replacement of receptor neurones after section of the vomeronasal nerves in the adult mouse.

Eight days after vomeronasal nerve section or removal of the accessory olfactory bulb, the majority of receptor cells of the vomeronasal neuroepithelium degenerate and disappear, leaving a regular framework consisting of supporting cells and their radial processes. The cell clusters at the boundaries of the epithelial sheet (which have been shown to be actively dividing in the normal, unoperated adult mouse) are also spared. The epithelium is subsequently repopulated by receptor cells appearing first in the basal part of the receptor cell layer and later occupying the full width of the receptor layer. These cells are anatomically fully differentiated receptor cells with normal sensory dendrites. Their axons form conspicuous intraepithelial neuromatous masses. Administration of [3H]thymidine on days 10-20 postoperatively labels some clusters of supporting cells and virtually all of the receptor cells, indicating that the repopulation of the epithelium is due to new formation of receptor cells.

Animals↗