Biomedical subjects

C Bell

Publications and source records attributed to C Bell.

At least 217 records · Page 12Linked to original sources

PubMed1987

Two classes of sympathetic nerves with different dopa decarboxylase immunoreactivities exist in dog vas deferens.

To determine whether dihydroxyphenylalanine (DOPA) decarboxylase (DDC) activity in the terminal regions of noradrenergic axons varies with axonal length, we compared the pattern of immunohistochemical staining for DDC in the 'short' terminal nerves of dog vas deferens with that in the 'long' nerves of spleen and atrium. The terminal nerves supplying the muscular coats of the vas deferens were, like those in spleen and heart, devoid of DDC immunoreactivity. The presence of this enzyme is therefore not characteristic of either short or long noradrenergic axons, in support of previous evidence that it is a specific marker for dopaminergic terminal nerves. Many axons supplying the mucosal epithelial cells in the vas deferens were DDC-positive, suggesting the existence of a dopaminergic innervation.

Animals↗

PubMed1987

The innervation of the caudal artery of the rat.

The sympathetic innervation of the main ventral artery of the rat tail has been studied using electrophysiological, histochemical and biochemical techniques. Excitatory junction potentials were evoked in the smooth muscle cells of an isolated segment (1-2 cm long) of the proximal vessel by stimulating its proximal end with a suction electrode. The amplitude of these potentials decreased distally until they were undetectable 6-8 mm from the stimulating electrode. The density of noradrenergic terminals along the length of the vessel was examined using formaldehyde-induced fluorescence and assay of endogenous noradrenaline, before and after lesioning the perivascular nerve plexus by freezing, or dividing the dorsal and ventral collector nerves. The results show that sympathetic axons run along the artery to make functional contact over only a few mm. Most (about 80%) of the sympathetic supply reaches the vessel after branching from the ventral collector nerves; the rest arises via the dorsal collector nerves. The location of the cell bodies of origin of the axons in the collector nerves has been identified after retrograde labelling with horseradish peroxidase. Motor and sensory axons in both dorsal and ventral nerve trunks arose from segments S2 to Co3, while almost all sympathetic neurons (95-98%) projecting to the tail were located in paravertebral ganglia S1 to S4 and the coccygeal ganglion. These results provide the first description of the relationship of the sympathetic innervation of the rat tail to its motor and sensory supply.

Animals↗

PubMed1987

Dopamine: precursor or neurotransmitter in sympathetically innervated tissues?

Dopamine represents 1-5% of the total catecholamine pool in sympathetically innervated tissues. A substantial proportion of this dopamine is located in vesicles, and nerve activation results in liberation of dopamine as well as noradrenaline. In certain tissues, there is neurochemical and functional evidence for the existence in addition of separate populations of dopaminergic sympathetic nerves. Some of the unsolved questions relating to the neural release of dopamine are: Is intravesicular dopamine in noradrenergic nerves a stable storage pool? Do noradrenergic nerves release dopamine and noradrenaline by identical mechanisms? What physiological roles do the sympathetic dopaminergic nerves play? What are the diagnostic and therapeutic implications of neural dopamine release?

Animals↗

PubMed1987

Endogenous renal dopamine and control of blood pressure.

Activation of specific receptors for dopamine in the renal vasculature and tubules leads to increases in glomerular filtration, and to diuresis and natriuresis. There is evidence for intrarenal production and release of dopamine, which may originate from two sources: tubular decarboxylation of plasma l-DOPA and a population of dopaminergic sympathetic neurons that innervate the renal cortex. Studies of plasma and urinary catecholamine levels indicate that dopamine is released within the kidney in response to sodium loading and to activation of sensory pathways related to nociception and chemoreception. There is also evidence for deficient renal release of dopamine in patients with renovascular or essential hypertension. Collectively, the available data suggest that intrarenal dopamine has a physiological function in control of blood volume and blood pressure, and that defects in this control may be implicated in the aetiology of some hypertensive states.

Animals↗

PubMed1986

Dopaminergic and noradrenergic sympathetic nerves of the dog have different DOPA decarboxylase activities.

We have compared the pattern of neural catecholamine fluorescence with that of immunoreactivity for the catecholamine-synthesizing enzymes tyrosine hydroxylase (TH) and DOPA decarboxylase (DDC) in dog atrium, which is innervated by noradrenergic nerves, and in dog kidney, which is thought to be supplied by dopaminergic nerves as well. In both tissues the distribution of nerves containing catecholamine fluorescence was similar to that of nerves exhibiting TH-like immunoreactivity. By contrast, DDC-like immunoreactivity was present in some (but not all) of the nerves associated with the intrarenal blood vessels, but was not detectable in any atrial nerves. High DDC activity provides further confirmation of the existence of sympathetic dopaminergic neurons supplying the kidney.

Animals↗

PubMed1986

Body image of anorexic, obese, and normal females.

This study investigated disturbances in body image perception with anorexic, obese and control groups (N = 24). Each group was comprised of 8 female subjects matched for age. An original silhouette chart and chi squares were employed, and a significant difference was found among the groups in the perception of the present-self body image (chi 2 (8) = 24.19, p less than .01), body image at plus 10 pounds (chi 2 (6) = 27.63, p less than .01), and body image at minus 10 pounds (chi 2 (8) = 26.05, p less than .01). No differences among the groups appeared in perceived ideal-self body image or in their perception of the body image that was expected from their families. A directional trend was noted in anorexic overestimation and obese underestimation on the total concept of body image. Significant differences among the groups as judged via a semantic differential technique were found for personality descriptions of happy/sad, active/passive, popular/unpopular, effective/ineffective, competent/incompetent, smart/stupid, and cold/warm.

Adolescent↗

PubMed1986

Localization of sympathetic and sensory neurons innervating the rat kidney.

Following injection of horseradish peroxidase (HRP) into the hilar region of the left kidney of the rat, 66% of labeled sympathetic neurons were located in the ipsilateral paravertebral ganglia, with most cells in T13 and L1, and 14% were located in equivalent segments of the contralateral chain. A similar distribution of sympathetic neurons projected to the right kidney, with most cells in T12 and T13 paravertebral ganglia. Only 20% of the total sympathetic supply to either kidney arose from the prevertebral ganglia. The renal sensory innervation was also bilateral in origin, with about 80% of the neurons arising from ipsilateral dorsal root ganglia. Injection of HRP into the caudal and rostral poles of the left kidney labeled paravertebral neurons which were concentrated in ganglia L1 and T13, respectively, but did not label any sensory neurons. We conclude that most of the renal sympathetic innervation is paravertebral in origin, and that a substantial bilateral component exists for both sympathetic and sensory supplies. Neurons arising from the contralateral side have their cell bodies in segments that provide the main ipsilateral innervation to the same kidney. The majority of sensory axons appear to be restricted to subcortical areas.

Adrenergic Fibers↗

PubMed1986

Vesicular storage of 3,4-dihydroxyphenylethylamine and noradrenaline in terminal sympathetic nerves of dog spleen and kidney.

The subcellular distribution of 3,4-dihydroxyphenylethylamine (DA, dopamine) and noradrenaline was examined in preparations of dog spleen and renal cortex following ultracentrifugation on a discontinuous sucrose gradient. In both tissues, only half the total tissue DA was localized to the soluble phase, and 30-50% was found in association with noradrenaline in the large vesicular fraction, suggesting that both catecholamines may be stored together and released by nerve stimulation. The vesicular fraction from renal cortex contained more DA than could be attributed to its presence in noradrenergic axons alone, supporting other evidence for the existence of dopaminergic renal nerves.

Animals↗

PubMed1986

Neuronal and nonneuronal contributions to renal catecholamine content in the dog.

Endogenous noradrenaline and 3,4-dihydroxyphenylethylamine (dopamine) levels were measured in different zones of the dog kidney following chronic unilateral renal denervation. In outer and inner renal cortex, and in outer medulla, greater than 95% of the tissue content of both catecholamines was contributed by renal nerves, whereas in inner medulla only nonneuronal catecholamines were found. The amounts of neuronal dopamine present in outer renal cortex were greater than would be expected for a population of solely noradrenergic nerves.

Animals↗

PubMed1986

Quantitative and qualitative analyses of serum antibodies elicited in adults by Haemophilus influenzae type b and pneumococcus type 6A capsular polysaccharide-tetanus toxoid conjugates.

Covalent binding to immunogenic proteins increases the immunogenicity of the capsular polysaccharides of Haemophilus influenzae type b (Hib) and pneumococcus type 6A (Pn6A). Conjugates composed of Hib, Pn6A, or the cross-reacting Escherichia coli K100 covalently bound to tetanus toxoid (TT) were injected into young adult volunteers. Local reactions were common and were probably due to Arthus reactivity mediated by the preexisting antibodies reacting with the TT component of the conjugates. Fever occurred in about 10% of the volunteers after the first injection; no volunteers had fever after the second injection. Similar levels of Hib or Pn6A antibodies were elicited by either 50- or 100-micrograms doses or by concurrent injection of two different conjugates (Hib-TT and Pn6A-TT or Hib-TT and K100-TT). The Hib-TT elicited about a 180-fold increase in Hib antibodies, and the Pn6A-TT conjugate elicited about an 8-fold increase in Pn6A antibodies after one injection. Booster reactions were not elicited in adults; similar levels of antibodies in the five experimental groups suggested that the responses elicited by the conjugates were maximal. A one-way cross-reaction was noted as Pn6A conjugates elicited rises of Hib antibodies in 13 of 20 volunteers; only 4 of 59 volunteers immunized with Hib-TT had increases in Pn6A antibodies. The preimmunization Hib antibodies were composed of immunoglobulin M (IgM), IgA, and IgG. The postimmunization sera showed an increase in all three isotypes; the elevation of the IgG was the highest of the three isotypes. Conjugate-induced antibodies to both the polysaccharide and TT exerted biological activities that have been correlated with immunity. Adsorption of the Hib-TT onto aluminium hydroxide resulted in higher levels and an earlier Hib antibody response in infant rhesus. These results encourage the evaluation of Hib and Pn6A conjugates in human children and infants.

Adjuvants, Immunologic↗

PubMed1986

Catecholamines in kidneys of normotensive and genetically hypertensive rats. Effects of salt load.

The tissue content of norepinephrine, dopamine, and epinephrine was determined in different zones of the kidney in normotensive Sprague-Dawley and Otago Wistar rats and in genetically hypertensive Otago Wistar rats. One kidney in each animal was chronically denervated to allow estimation of the neuronal contribution to renal catecholamine content. In all strains, the renal cortex contained negligible amounts of nonneuronal norepinephrine and dopamine, while outer and inner medullary layers contained progressively larger amounts. Nonneuronal epinephrine was distributed fairly evenly through cortex and medulla. Neuronal norepinephrine content was similar in inner and outer cortex, substantially less in outer medulla, and not discernible in inner medulla. The amounts of neuronal dopamine were consistent with its localization predominantly in noradrenergic nerves. The renal cortices of normotensive Wistar rats contained more neuronal norepinephrine and less neuronal dopamine than those of Sprague-Dawley rats, and the cortices of hypertensive Wistar rats contained slightly more norepinephrine than those of normotensive Wistar rats. In both normotensive strains, long-term salt loading decreased selectively the neuronal norepinephrine in renal cortex. By contrast, in hypertensive animals, cortical norepinephrine was not reduced by salt loading. These results indicate that the genetically hypertensive rat may have an abnormal sympathetic reflex response to increased blood volume.

Animals↗

PubMed1985

Substance P-immunoreactive nerves in the rat kidney.

Previously published data have indicated that in the rat, unlike other species examined, the kidney is not supplied by sensory nerves containing substance P (SP). As part of a study of reflex control of renal function in the rat, we have now reassessed this situation. Many fine, varicose, SP-immunoreactive nerve fibers were found in the wall of the proximal ureter and the renal pelvis, and around the larger renal blood vessels. Sparser populations of similar nerves were also seen running close to proximal and distal tubules in the renal cortex. Occasional fibers were seen at the margins of the glomeruli. Our findings suggest that sensory nerves containing SP may carry sensory information of several types from the rat kidney.

Animals↗

PubMed1985

Simultaneous recording of penile diameter and penile arterial pulse during laboratory-based erotic stimulation in normal subjects.

We have assessed erectile responses of normal male subjects to short periods of fantasy and to short erotic films, using simultaneous measurement of penile diameter and penile dorsal arterial pulse amplitude, together with systemic arterial blood pressure, heart rate and skin blood flow. By a variety of criteria, we have satisfied ourselves that penile pulse amplitude reflected local vascular changes in the penis rather than changes in systemic blood pressure, although it is uncertain whether it was primarily determined by the magnitude of arterial flow or that of arterial volume. Penile pulse amplitude usually increased markedly during the stimulation period, and was correlated with penile erection. The temporal relationship between these two parameters was variable. Typically pulse amplitude increase started later than diameter increase but thereafter changed in parallel. In a proportion of responses, however, these two changes were markedly dissociated in time and these responses tended to be slower in reaching their maximum diameter. This variable association suggests that two separate processes involved in erection are being measured. Simultaneous monitoring of penile diameter and penile pulse may therefore provide further information about the basic physiological processes involved in penile erection as well as diagnostic information in patients with erectile dysfunction of uncertain aetiology.

Adult↗

PubMed1985

Assessment of erectile function in diabetic and non-diabetic impotence by simultaneous recording of penile diameter and penile arterial pulse.

Simultaneous monitoring of penile diameter and penile arterial pulse during laboratory-based erotic stimulation with film and fantasy, has been used to compare diabetic and non-diabetic impotent men with non-impotent controls. The degree of erection to erotic film distinguished between organic and psychogenic aetiologies. The diabetic group showed smaller penile pulse amplitude changes than the other two groups. Amongst the diabetics, severe autonomic neuropathy was associated with impaired erectile and penile pulse amplitude responses. Severe retinopathy was associated with smaller baseline penile pulse amplitude as well as smaller amplitude response. Blood pressure response to erotic stimuli did not differ between the three groups. An analysis of the temporal relationship between penile diameter change and pulse amplitude change revealed differences between the groups that may prove to have diagnostic as well as theoretical implications.

Adult↗

PubMed1985

Differentiation of neurogenic vasoconstrictor responses in skin and skeletal muscle of dog hindlimb.

Femoral blood flow was measured electromagnetically in chloralose-anaesthetised dogs pretreated with atropine and pancuronium, during preganglionic stimulation of the ipsilateral lumbar sympathetic chain. Circulation to the paw pads was occluded with a ligature. Trains of 10 stimuli at frequencies of 4 or 40 Hz elicited vasoconstrictor responses, the recovery phases of which were prolonged during temporary occlusion of the circulation to the leg below the knee, and shortened in the presence of low doses of the ganglion blocking drug hexamethonium (0.5-3 mg/kg i.v.). Numerical summation of the responses persisting after 2 mg/kg hexamethonium and those obtained during lower limb occlusion produced curves that closely matched control responses in timecourse and amplitude. It is suggested that skin and muscle resistance vessels in the hindlimb receive their primary vasoconstrictor nerve supply via peripheral pathways that can be distinguished by the sensitivity to hexamethonium of their ganglionic synapses, and that the timecourse of constrictor responses in skeletal muscle is longer than that in skin.

Animals↗

PubMed1985

Comparison of the antagonistic effects of phentolamine on vasoconstrictor responses to exogenous and neurally released noradrenaline in vivo.

The antagonistic effects of the alpha-adrenoceptor blocking agent phentolamine on vasoconstrictor responses to intraluminal noradrenaline and lumbar sympathetic nerve stimulation were compared in the hindlimb of the anaesthetized dog. Sympathetic stimulation with 1 pulse or trains of 4-10 pulses at 0.4-40 Hz produced graded vasoconstrictor responses that were matched in amplitude by intra-arterial injections of 10(-8) - 10(-6) g noradrenaline. Phentolamine (0.5 mg kg-1 i.v.) attenuated amplitude-matched responses to both types of stimuli to quite similar extents. The extent of the effect of phentolamine on neurogenic responses was greater with 1 pulse stimulation than with trains, and greater with 4 pulse than with 10 pulse trains. The effect was maximal within 2 min of phentolamine administration and wore off in parallel with that on responses to injected noradrenaline. The results are consistent with the view that transmitter released from noradrenergic vasoconstrictor nerves acts primarily on subjunctional alpha-adrenoceptors.

Animals↗

PubMed1985

Differentiation of vasodilator and sudomotor responses in the cat paw pad to preganglionic sympathetic stimulation.

We monitored sweat secretion (using skin potential) and blood flow (using skin temperature) in the hind-paw skin of chloralose-anaesthetized cats pre-treated with guanethidine, and studied the responses to electrical stimulation of the ipsilateral lumbar sympathetic trunk. Stimulation caused sweat secretion and an increase in skin blood flow which was almost entirely restricted to the paw pads and was completely ipsilateral. Stimulation of the tibial nerve trunk produced similar effects, except that the increase in blood flow was more prolonged. The vasodilator effect of sympathetic trunk stimulation was not affected by chronic deafferentation of the paw. Atropine methonitrate (0.5-1 mg/kg I.V.) abolished the sudomotor response to sympathetic stimulation, but did not attenuate the blood flow response. Hexamethonium (1-2 mg/kg I.V.) abolished the vasodilator response to sympathetic stimulation, but did not affect the sudomotor response. Larger doses of hexamethonium (10-20 mg/kg) abolished both responses. The data suggest that the lumbar post-ganglionic neurones mediating vasodilatation in the skin of the cat paw pad are distinct from those that mediate sudomotor secretion.

Animals↗

PubMed1985

A life skills program for physically disabled adolescents.

Successful management of one's life involves the ability to solve problems, set realistic goals, make and evaluate decisions, and utilize personal and interpersonal skills. Adolescence is that time during which individuals are expected to develop these "life skills" that will enable them to cope effectively with the demands of daily living. Due to many factors, physically disabled adolescents frequently experience delay and difficulty in mastering the developmental tasks of this period. Formalized training in life skills is one approach that has the potential to equip these young people with the skills and strategies needed for adult independence. This paper describes the unique stresses of adolescence as experienced by the physically disabled population and the development of a Life Skills Program at the Hugh MacMillan Medical Centre designed to address some of these issues.

Adolescent↗