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Biomedical subjects

C Bell

Publications and source records attributed to C Bell.

At least 235 records · Page 13Linked to original sources
PubMed1984

Eye color as a predictor of outcomes in behavior therapy.

Eye color research has centered primarily on the dimension of self-paced vs. reactive performance. Self-paced activities are those in which the individual may initiate the activity when he/she chooses while the stimulus situation remains relatively constant. Reactive activities must be initiated at the precise time dictated by a rapidly changing stimulus situation. The present study examined the relationship between outcomes of behaviorally oriented treatment for children (N = 366) and eye color. The findings were consistent with theoretical expectations: Dark-eyed children and teenagers responded better to reactive treatment programs than their light-eyed counterparts, while the reverse was true for self-paced treatment programs. Implications for research and practice were discussed.

Adolescent↗
PubMed1984

Small fluorescent cells in the rat kidney contain 5-hydroxytryptamine not a catecholamine.

The rat kidney contains and excretes more dopamine than can be attributed solely to its originating from intrarenal noradrenergic nerves and plasma-free dopamine. It has recently been suggested that the source of this excess dopamine may be a population of small cells that are present in the renal medulla, and which by fluorescence and electron microscopy appear to contain high concentrations of a monoamine. We have therefore further investigated these cells. After formaldehyde treatment the fluorescence of the cells was characteristic of indoleamines rather than of catecholamine-containing structures. They did not form a visible precipitate with chromium salts in the classic chromaffin reaction. DOPA decarboxylase-like immunoreactivity was present in the adrenal medulla but not in the intrarenal cells or in mesenteric mast cells. 5-hydroxytryptamine (5-HT)-like immunoreactivity was seen in the intrarenal cells and in mesenteric mast cells, but was not evident in adrenal medullary cells. These results indicate that the intrarenal cells are 5-HT-containing mast cells and do not contribute to renal dopamine production.

Adrenal Medulla↗
PubMed1984

Distribution of neurones containing DOPA decarboxylase and dopamine-beta-hydroxylase in some sympathetic ganglia of the dog: a quantitative study.

Using a technique by which binding sites for two antibodies can be visualized in single tissue sections, we have studied the distribution of neurones containing DOPA decarboxylase-like and dopamine beta-hydroxylase-like immunoreactivity in ganglia of dog sympathetic chain. Three types of neurones could be distinguished: those that contained both enzymes, and were presumably noradrenergic; those that contained neither enzyme, and were presumably not catecholaminergic; and a group that contained DOPA decarboxylase but lacked dopamine beta-hydroxylase. The numbers of cells of each type were counted in serially-sectioned ganglia from regions of the sympathetic chain thought to contain dopaminergic neurones (T12-L1 and L7-S2). The percentages of total cell numbers contributed by the DOPA decarboxylase-positive, dopamine beta-hydroxylase-negative cells in these regions were similar to the estimates of dopaminergic neurone numbers that can be made from previously obtained biochemical data. Our results are consistent with the presence of dopaminergic neurons in regions of the paravertebral chain supplying the kidney and the distal hindlimb.

Animals↗
PubMed1984

Characterization of chromaffin-like cells in the canine sympathetic chain by enzyme immunohistochemistry and quantitation of their distribution.

Some of the paravertebral sympathetic ganglia of the dog contain relatively large amounts of dopamine, which we have suggested previously is localized in dopaminergic neurones. However, the possibility exists that intraganglionic chromaffin-like cells may also be a source of dopamine. In order to resolve this question, we have examined the distribution of chromaffin-like cells in dog paravertebral ganglia (T7-S2) using formaldehyde-induced fluorescence of catecholamines and immunohistochemical localization of dopa decarboxylase, dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase. The results have been compared with levels of the different endogenous catecholamines in equivalent ganglia. Clusters of between 20 and several thousand chromaffin-like cells were randomly present in ganglia at all levels of the chain, and were most common in the more caudal segments (L4 or below); but many ganglia contained no cells. About 24,000 chromaffin-like cells were found in 18 ganglia from six animals which were stained for dopa decarboxylase and dopamine beta-hydroxylase. In 16 of these ganglia, all of the 17,000 cells present contained both enzymes, indicating that they could synthesize noradrenaline. In the remaining two ganglia, 500 out of 7000 cells contained dopa decarboxylase, and therefore were capable of synthesizing dopamine, but appeared to lack the dopamine beta-hydroxylase necessary to convert this to noradrenaline. Five ganglia from three other dogs were stained for dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase. A further 2600 cells were found in these ganglia and both enzymes were present in all of the cells, indicating that they could all synthesize adrenaline. Biochemical estimates of the various catecholamines showed that ganglia containing appreciable amounts of adrenaline had similar distributions to those containing chromaffin-like cells in the same animals. High concentrations of adrenaline were often correlated with high concentrations of noradrenaline but were not correlated with high concentrations of dopamine. It is concluded that paravertebral chromaffin-like cells in the dog store adrenaline, and also perhaps noradrenaline, but not dopamine. The high concentrations of dopamine found in certain ganglia cannot therefore be attributed to the presence of these cells. The erratic distribution of chromaffin-like cells suggests that they are unlikely to fulfil any general role in modulation of ganglionic transmission.

Animals↗
PubMed1984

The role of substance P in the axon reflex in the rat.

The increase in vascular permeability in small blood vessels of rat skin induced by antidromic stimulation of sensory roots, nerves, or single identified polymodal nociceptive fibres or by intra-arterial injection of Substance P, has been examined by light and electron microscopy. The effects of local application of capsaicin (a Substance P-depleting agent) to both skin and muscle have also been studied. Nerve stimulation and Substance P induce leakage of a venular pattern similar to that caused by known permeability factors. However, capsaicin causes leakage from both venules and capillaries in a pattern more characteristic of direct endothelial injury. It is suggested that neurogenic leakage may be mediated by local liberation of Substance P, but caution is necessary in interpreting experiments involving the use of capsaicin because of its local toxic effects.

Administration, Topical↗
PubMed1984

Release of noradrenaline and dopamine by nerve stimulation in the guinea-pig and rat vas deferens.

Spontaneous and nerve stimulated release of noradrenaline and dopamine from rat and guinea-pig vas deferens have been measured electrochemically after separation by high performance liquid chromatography (h.p.l.c.). In the absence of nerve stimulation both noradrenaline (NA) and dopamine were released into the bathing fluid in the rat but in the guinea-pig only noradrenaline could be detected. Drugs which block neuronal and extraneuronal uptake of catecholamines had little effect on spontaneous overflow but both tetraethylammonium and phenoxybenzamine increased overflow. Transmural nerve stimulation (5-10 Hz) increased catecholamine overflow in both species and dopamine release was now measurable from the guinea-pig vas. In the rat, the proportion of dopamine to NA was unchanged from that released spontaneously. The release of both amines was little affected by drugs that block neuronal and extraneuronal uptake and a monoamine oxidase inhibitor, but was inhibited by tetrodotoxin 0.2 microgram ml-1. In the guinea-pig tetraethylammonium 10 mM doubled overflow and phenoxybenzamine 10(-5)M increased it by five times but the dopamine percentage remained constant and equal to the control. Following nerve stimulation the amount of dopamine released expressed as a percentage of total catecholamine release was 6% for the rat and 1.3% for the guinea-pig. These values were considerably higher than the comparable figures for dopamine: NA content of the two tissues (2% and 0.5% respectively). Repeated periods of stimulation depleted these tissue stores and the depletion of dopamine was significantly greater than that of NA. 6 Our interpretation of these results is that both dopamine and NA are released from a common store during normal noradrenergic transmission. While all or most of the axonal dopamine is contained in this releasable pool, most of the axonal NA lies in a second, less readily released pool.

Animals↗
PubMed1984

Pharmacological investigations of the vasodilator nerves supplying the duck's foot.

Vasodilator responses to electrical nerve stimulation and to various putative autonomic inhibitory neurotransmitters were studied in the Krebs-perfused foot of the domestic duck. Electrical stimulation resulted in frequency-dependent vasoconstrictor responses which were abolished by the infusion of guanethidine. After abolition of the vasoconstriction, electrical stimulation produced a frequency-dependent vasodilatation. The putative inhibitory transmitter substances tested were substance P, somatostatin, vasoactive intestinal polypeptide, adenosine triphosphate and dopamine. Of these only dopamine produced dilator responses similar in appearance to those following nerve stimulation. Infusion of metoclopramide (170 microM) greatly reduced dilator responses to nerve stimulation and to dopamine but not those to glyceryl trinitrate. These results suggest that the vasculature of the duck foot may be supplied by dopaminergic vasodilator nerves.

Adenosine Triphosphate↗
PubMed1983

Location of dopamine stores in rat kidney.

In normotensive and genetically hypertensive Wistar rats, chronic renal denervation reduces renal cortical levels of noradrenaline and dopamine by more than 90%. Non-neural stores of renal dopamine are therefore small or absent.

Animals↗
PubMed1983

Problems and ambiguities in the identification of autonomic neurotransmitters.

Although the traditional classification of autonomic neurons as either cholinergic or adrenergic is still subscribed to in most textbooks of physiology, it is apparent that many of the postganglionic neurons do not fall readily into either of these categories. Upwards of a dozen other transmitter candidates have been proposed, but in no instance has the identity of a non-cholinergic, non-adrenergic autonomic transmitter been established. In this paper some of the problems and ambiguities relating to satisfaction of the classical criteria for neurotransmitter identification are briefly surveyed, with special reference to the neuropeptides.

Animals↗
PubMed1983

Catecholamines in the sympathetic nervous system of the domestic fowl.

In order to resolve some existing uncertainties regarding the identity of the sympathetic catecholamine neurotransmitter in birds, we have measured endogenous noradrenaline (NA), adrenaline (AD) and dopamine (DA) in various peripheral tissues and in the paravertebral sympathetic chain of the domestic fowl. In all visceral tissues examined - atrium, spleen, mesenteric artery, gizzard, intestine, rectal caecum and kidney--NA concentrations were much higher than those of AD or DA. The ratios of NA:AD:DA were approximately 100:10:1 for all tissues except spleen, in which DA represented about 10% of the total catecholamines. In the paravertebral chain, the ratio of NA:DA was about 4:1, with no consistent segmental differences. Ganglionic AD was generally less than 1% of the total catecholamine, but isolated ganglia sometimes contained quite large amounts of AD. This AD was probably in chromaffin cells. The results obtained indicate that, contrary to some previous reports, NA constitutes the predominant sympathetic neurotransmitter in the fowl, and neurons in which AD is a transmitter are rare or absent. Although the relatively large amounts of DA present in the ganglia could be due to presence of dopaminergic neurons, no evidence for peripheral projections of such neurons was obtained.

Animals↗
PubMed1983

Neural and non-neural components of the developing hypertension in genetically hypertensive rats.

Blood pressures of Otago genetically hypertensive (GH) rats are higher than those of genetically related normotensive (N) rats as early as 35 days after birth. At this age, the elevation of blood pressure is entirely neurogenic, as both GH and N animals have similar blood pressures following ganglion blockade; however, by age 45 days an additional non-neural component of the hypertension has appeared, and this persists into adulthood. Chronic treatment with propranolol or atenolol (1 mg/kg/day) over days 28-90 does not attenuate the development of hypertension. Neonatal sympathectomy with guanethidine almost abolishes resting sympathetic tone even in adult (GH) animals, but does not prevent the appearance of the non-neural component of the hypertension. It is concluded that although sympathetic nervous tone contributes to the absolute level of blood pressure in GH rats, it is not a causative factor in the development of hypertension.

Age Factors↗
PubMed1983

Pneumothorax in drug abusers: a complication of internal jugular venous injections.

We report the cases of six patients who suffered pneumothorax following admitted drug injection into the internal jugular vein area. One was treated in the hospital with observation and serial roentgenograms, two were treated with chest tube thoracostomy, and three left the emergency department against medical advice and were lost to follow up. As increasing numbers of parenteral addicts turn to central venous injection sites, this complication is likely to become more common.

Adult↗
PubMed1982

Absence of dopamine-beta-hydroxylase in some catecholamine-containing sympathetic ganglion cells of the dog: evidence for dopaminergic autonomic neurones.

Previous pharmacological and biochemical findings have suggested the presence of dopaminergic vasomotor neurones in the sympathetic outflows to the kidney and the digits of the dog. In the present study, we have used histochemical techniques to compare the distributions of catecholamines and dopamine-beta-hydroxylase-like immunoreactivity in ganglion cell bodies of the sympathetic chain. The results indicate that some neurones in the ganglia supplying the kidney and the hindlimb store a catecholamine but lack dopamine-beta-hydroxylase. This finding supports the existence of dopaminergic sympathetic neurones.

Acetylcholinesterase↗