Search PubMed⌕ Search

Biomedical subjects

C Bell

Publications and source records attributed to C Bell.

At least 163 records · Page 9Linked to original sources
PubMed1991

Effectiveness of source documents for identifying fatal occupational injuries: a synthesis of studies.

BACKGROUND: The complete and accurate identification of fatal occupational injuries among the US work force is an important first step in developing work injury prevention efforts. Numerous sources of information, such as death certificates, Workers' Compensation files, Occupational Safety and Health Administration (OSHA) files, medical examiner records, state health and labor department reports, and various combinations of these, have been used to identify cases of work-related fatal injuries. Recent studies have questioned the effectiveness of these sources for identifying such cases. METHODS: At least 10 studies have used multiple sources to define the universe of fatal work injuries within a state and to determine the capture rates, or proportion of the universe identified, by each source. Results of these studies, which are not all available in published literature, are summarized here in a format that allows researchers to readily compare the ascertainment capabilities of the sources. RESULTS: The overall average capture rates of sources were as follows: death certificates, 81%; medical examiner records, 61%; Workers' Compensation reports, 57%; and OSHA reports 32%. Variations by state and value added through the use of multiple sources are presented and discussed. CONCLUSIONS: This meta-analysis of 10 state-based studies summarizes the effectiveness of various source documents for capturing cases of fatal occupational injuries to help researchers make informed decisions when designing occupational injury surveillance systems.

Accidents, Occupational↗
PubMed1991

Topography of functional subpopulations of neurons in the superior cervical ganglion of the rat.

This study describes the distribution patterns of neurons in the rat SCG that project to a number of spatially separated and functionally different target tissues. Fluorescent dyes were used to label retrogradely neurons that project to the pineal gland, iris, nictitating membrane, Müller's smooth muscle of the eyelid, submaxillary gland, thyroid gland, tongue, buccal mucosa, and skin in several areas of head and neck. The numbers of neurons in the various subpopulations were quantified and, in several instances, postganglionic nerve transection was used to correlate the topography of subpopulations with the exit site/s of their projections from the ganglion. Individual neurons were found to have very limited projection fields and contralateral innervation of bilateral targets appeared to be minimal. Neurons with specific functions or projection fields were not highly localised within the SCG, but there was a general rostrocaudal organisation of neurons with respect to the position of their targets along the rostrocaudal axis of the body and this was correlated with the exist sites of the neurons from the ganglion.

Animals↗
PubMed1990

The use of a genotypic marker to demonstrate clonal dominance during the growth and metastasis of a human breast carcinoma in nude mice.

When a mixture of 11 clones of a human breast carcinoma (MDA-MB-435)--each clone transfected with pSV2neo and identified as having a unique insertion site of the gene--was injected into nude mice, the resulting tumors were found to contain only one clone (Neo 24). This clone, identified by the unique restriction fragments on Southern blot analyses, was also found in metastases recovered from the lungs and lymph nodes of the animals. The individual clones showed no differences in in vitro growth, while in vivo the Neo 24 cells produced the largest tumors. Thus, one explanation for the observed clonal dominance in this study could be the more rapid growth in vivo of the Neo 24 cells. This study illustrates how an introduced selectable gene marker can be used in lineage studies of human tumor cell populations.

Animals↗
PubMed1990

The impact of sexual dimorphism on neuron numbers in the superior cervical ganglion of the rat.

Other workers have reported a sexual dimorphism in the number of neurons that project from the rat superior cervical ganglion (SCG) via the internal carotid nerve (ICN). We have re-examined this situation by comparing ganglionic neuron numbers as well as the number of neurons labelled retrogradely from the iris and the pineal gland, in age-matched adult male and female rats. No significant dimorphism was seen in total cell numbers or in the cell populations supplying iris or pineal gland, although there was a trend towards more neurons in male animals. From evaluation of our results and the published data, we suggest that the variation in absolute numbers of neurons counted in the SCG is so wide, within genders, that any impact of gender differences on cell numbers is of little significance.

Animals↗
PubMed1990

Identification of dopaminergic nerves in humans.

It has been well-documented in animal studies that axons of dopaminergic neurons can be distinguished from those of noradrenergic neurons by their content of DOPA decarboxylase (DDC). We now have evidence that DDC immunoreactivity is also specific for dopaminergic axons in the sympathetic nervous system of man. Thus, light microscope immunocytochemistry can be used to screen human tissues for potential dopaminergic inputs, preparatory to functional analysis. Application of this technique has so confirmed the innervation by dopaminergic neurons of human kidney and hepatic vasculature. Although similar nerves are found in kidney and liver of dog, the specific target structures supplied, and therefore the specific functional effects of nerve activation, are different.

Dopamine↗
PubMed1990

A functional role for renal dopaminergic nerves in the dog.

1. Efferent renal nerve stimulation at 5 Hz causes secretion of both dopamine (DA) and noradrenaline (NA) into renal venous plasma. DA comprises about 8% of the total catecholamine overflow; by contrast, DA efflux into femoral venous plasma following stimulation of the lumbar sympathetic nerves is 1% or less of total catecholamine. 2. Intact, but not denervated, kidneys of volume-loaded dogs also secrete both dopamine (DA) and noradrenaline (NA) into renal venous blood at rest, but the DA:NA ratio is considerably higher than that evoked by nerve stimulation. 3. Acute animal treatment with 6-hydroxydopamine (6-OHDA) abolishes stimulus-evoked catecholamine overflow and the usual fall in glomerular filtration and sodium and water excretion that accompanies renal nerve activation. 4. When 6-OHDA is administered in the presence of a selective inhibitor of UptakeDA (GBR 12909), stimulus-evoked DA overflow is selectively protected against the effect of 6-OHDA. Under these circumstances, nerve stimulation increases glomerular filtration and excretion of water, but not of sodium. These effects are abolished by DA1 receptor blockade. 5. These data indicate that DA is released from intrarenal dopaminergic nerve terminals in vivo, both in response to direct nerve stimulation and tonically under conditions of volume expansion. The main effects of dopaminergic nerve activation are juxtaglomerular vasodilatation and inhibition of distal tubular water reabsorption.

Animals↗
PubMed1990

Effects on renal sympathetic axons in dog of acute 6-hydroxydopamine treatment in combination with selective neuronal uptake inhibitors.

1. In anaesthetized dogs, we have investigated the effect on renal responses to sympathetic nerve stimulation of acute treatment with the catecholaminergic neurotoxin 6-hydroxydopamine (2 mg kg-1 i.v.), administered alone or after blockade of neuronal catecholamine uptake pathways for noradrenaline (NA) or dopamine with desmethylimipramine or benztropine, respectively. 2. Under control conditions, renal nerve stimulation caused renal vasoconstriction, reduced glomerular filtration and sodium and water excretion and caused net efflux of NA and dopamine into the renal venous plasma. Two h after administration of 6-hydroxydopamine alone, there was abolition of both functional responses and catecholamine efflux during nerve stimulation. 3. In animals pretreated with desmethylimipramine (1 mg kg-1), 6-hydroxydopamine had no significant effect on functional responses to renal nerve stimulation and nerve-evoked efflux of NA was only moderately reduced. Efflux of dopamine was still markedly reduced by 6-hydroxydopamine, but more variably than occurred without desmethylimipramine treatment. 4. In animals pretreated with benztropine (0.2 mg kg-1), nerve-evoked efflux of dopamine, but not that of NA, was protected against reduction by 6-hydroxydopamine. A higher dose of benztropine (1 mg kg-1) protected efflux of both NA and dopamine against 6-hydroxydopamine. 5. We conclude that acute treatment with a low dose of 6-hydroxydopamine is an effective method of inactivating peripheral sympathetic nerves. The differential effects of desmethylimipramine and benztropine in preserving nerve-evoked efflux of NA and dopamine after 6-hydroxydopamine support the view that these catecholamines originate predominantly from different intrarenal axons. However, neither uptake blocker appears to be completely specific in its actions.

Animals↗
PubMed1990

Effects of selective blood and tissue heating on blood flow in the dog hindlimb.

This study investigated the effects of independent and combined heating of blood and tissue to 40-44 degrees C on femoral blood flow in the hindlimb of the anaesthetized dog. An increase in arterial blood temperature by means of an extracorporeal circuit increased femoral vascular resistance. An increase in limb tissue temperature, induced by external hot packs, decreased femoral vascular resistance. These responses occurred both before and after sympathetic blockade. Neither blood heating nor tissue heating affected the hyperaemic response to exercise. When blood and tissue heating were combined, femoral vascular resistance remained unaffected. We conclude that changes in blood temperature do not contribute to the hyperaemic effect of limb warming and that exercise combined with limb warming is no more effective as a therapeutic tool for promoting limb flow than exercise alone.

Animals↗
PubMed1990

Effects of microwave irradiation on blood flow in the dog hindlimb.

Physiotherapeutic doses of microwave irradiation to the hindlimb of the anaesthetized dog increased the temperature in the underlying skin and muscle by 5-6 degrees C and, after a latency of 2-8 min, heart rate, blood pressure and femoral conductance all increased. The conductance increase was predominantly in the paw. At this time plasma catecholamine levels were elevated above resting values. At the conclusion of irradiation, heart rate and blood pressure rapidly returned to basal levels, but there was a sustained increase in femoral conductance which was mainly in the leg. The results are discussed in terms of the likely mechanisms underlying the effects of microwave irradiation on limb blood flow and compared with those obtained with direct heating of arterial blood and limb tissue in the accompanying paper.

Animals↗
PubMed1990

Neuropeptide Y in rat sympathetic neurons is altered by genetic hypertension and by age.

We have used immunocytochemistry to quantitate neuronal neuropeptide Y in superior cervical ganglia of a strain of normotensive Wistar-Otago rats and a related genetically hypertensive strain over the age range 1-60 weeks. The numbers of neuropeptide Y-immunoreactive cells and total ganglionic cell numbers were both greater in ganglia of young normotensive than in those of hypertensive rats. Between 10 and 60 weeks of age, peptide immunoreactivity and total cell numbers both fell in normotensive rat ganglia but remained constant in ganglia from hypertensive rats. Densitometric analysis showed that the concentrations of neuropeptide Y were similar in neurons of age-matched individuals of both strains, but during aging there was a substantial decline in neuronal peptide content that was similar in both strains and that was not accompanied by any decline in neuronal immunoreactivity for tyrosine hydroxylase. Our results suggest that there is a developmental abnormality of neuropeptide Y in sympathetic neurons of this strain of genetically hypertensive rat and that, furthermore, the aging process is accompanied by a selective loss of neuronal neuropeptide Y that is independent of blood pressure status.

Aging↗
PubMed1990

Creating a new nurse specialist post.

Studies have shown the improvement in the quality of care which is achievable when clinical nurse specialists are introduced in the management of patient care. The field of respiratory care appears to be an appropriate setting for specialist nursing roles. The previous paper (Carswell et al) adds weight to the notion that there is room for improvement in the care of patients with respiratory problems. This paper provides the background to the development of a clinical nurse specialist role in respiratory care.

Bronchoscopy↗
PubMed1989

Different patterns of immunolocalization of calcitonin gene-related peptide and substance P in sympathetic ganglia of normotensive and genetically hypertensive rats.

Calcitonin gene-related peptide (CGRP) and substance P (SP) immunoreactivity were investigated in the superior cervical ganglion of normotensive and genetically hypertensive Otago Wistar rats by an immunoperoxidase method. CGRP- and SP-positive varicose axons invested separate subpopulations of ganglion cells, neither of which contained neuropeptide Y. The densities of CGRP axons were similar in normotensive and hypertensive rats while the numbers of SP axons were several times higher in the hypertensive strain. Decentralization of the ganglion or chronic capsaicin treatment removed all immunoreactive terminals, indicating that both axon populations are likely to be collaterals from thoracic sensory afferents.

Animals↗
PubMed1989

Co-inoculation of tumorigenic rat prostate mesenchymal cells with non-tumorigenic epithelial cells results in the development of carcinosarcoma in syngeneic and athymic animals.

Co-inoculation of NbF-I and NbE-I s.c. into either adult male syngeneic rats or athymic nude mice induced the development of tumors that resembled carcinosarcoma on histopathologic evaluation. These tumors were composed of a mixture of adenocarcinoma and fibrosarcoma and were induced by the mixtures of NbF-I and NbE-I cells at a ratio ranging from 0.001 to 3.2; inoculation of NbF-I alone resulted in the development of fibrosarcoma. Flow-cytometric analysis showed that the epithelial cells subcloned from the carcinosarcoma had a DNA profile like that of their parental cell line and remained non-tumorigenic. When co-inoculated with the tumorigenic fibroblasts in syngeneic hosts, however, the subcloned epithelial cells again formed carcinosarcomas. Our results indicate that cell fusion between epithelial cells and fibroblasts is an unlikely explanation for tumorigenicity. We propose that prostatic fibroblasts exert a directive influence on their adjacent epithelial cells through a paracrine mechanism that determines epithelial growth and tumorigenicity in vivo.

Animals↗
PubMed1989

Evidence that dopaminergic sympathetic axons supply the medullary arterioles of human kidney.

The ability of the kidney to excrete sodium appears to depend on release of dopamine from intrarenal sources. In the present study, we have used immunohistochemistry to examine the possibility that renal dopaminergic nerves constitute one of these sources. We found that the sympathetic axons supplying cortical structures in human kidney contain tyrosine hydroxylase-like immunoreactivity but lack DOPA decarboxylase-like immunoreactivity. By contrast, the vasa recta arterioles of the renal medulla are supplied by varicose tyrosine hydroxylase-positive nerve fibres, some of which also contain DOPA decarboxylase. As DOPA decarboxylase has been demonstrated in other situations to be a selective marker for dopaminergic terminal axons, our results suggest the innervation of renal medullary blood vessels in man by both noradrenergic and dopaminergic sympathetic nerves.

Adult↗
PubMed1989

Extrinsic denervation elevates neuronal aromatic L-amino acid decarboxylase immunoreactivity in rat small intestine.

In order to clarify further the neural control of digestive tract function, we have compared the neuronal localization of tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC) in rat small intestine. Immunoreactivity for TH was found in numerous varicose axons associated with neurons of the enteric plexuses and in axons within the circular muscular coat and the mucosal villi. Axons with AADC immunoreactivity had a similar distribution, but were sparser in the enteric plexuses and musculature than those containing TH. Chronic extrinsic denervation of a segment of intestine removed all TH-positive nerves from that region. By contrast, the intensity of AADC immunoreactivity was enhanced and more AADC-positive axons were visible than in adjacent intact areas of intestine. The AADC-positive axons appear to represent the intrinsic 'amine-handling' neurons rather than intrinsic tryptaminergic neurons or extrinsic dopaminergic neurons, and the effect on AADC activity of removing the extrinsic nerve supply suggests that this normally exerts some restraining influence on the metabolism of the 'amine-handling' population.

Animals↗
PubMed1989

Substance P immunoreactivity in the superior cervical ganglia of normotensive and genetically hypertensive rats.

Substance P-like immunoreactivity (SPI) was investigated in the superior cervical ganglion of normotensive and genetically hypertensive (GH) Otago Wistar rats aged 1, 2, 8-10 and 50-60 weeks, by used of an indirect immunoperoxidase method. SPI was not seen in neuronal cell bodies but a subpopulation of ganglion cells was supplied by SP-positive terminals which closely invested the cell surface. This subpopulation showed no particular topographical distribution. The number of SP-positive terminal varicosities per unit area was several times higher in GH rats than in normotensive rats at all ages over 2-60 weeks. The proportion of neurons supplied by SP-positive terminals (sampled in 8-10 week-old rats) was also greater in GH than in normotensive rats. Decentralization of the ganglion or chronic capsaicin treatment removed all SP-immunoreactive terminals around the cell bodies, indicating that the SP-positive terminals are collaterals of thoracic sensory afferents. As SP has been reported to have an excitatory effect in sympathetic ganglia, intraganglionic release of SP might contribute to the development of hypertension in the GH strain.

Aging↗