Biomedical subjects
Publications and source records attributed to J D Silverman.
Effective consultations with patients and their families are important for patient satisfaction, adherence to treatment, and recovery from illness. Communication problems among health professionals are common. Fortunately, the skills of effective communication can be taught and learned. This paper highlights evidence based approaches to teaching these skills with minimal resources.
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Effective communication between doctor and patient is a core clinical skill. It is increasingly recognized that it should and can be taught with the same rigour as other basic medical sciences. To validate this teaching, it is important to define the content of communication training programmes by stating clearly what is to be learnt. We therefore describe a practical teaching tool, the Calgary-Cambridge Referenced Observation Guides, that delineates and structures the skills which aid doctor-patient communication. We provide detailed references to substantiate the research and theoretical basis of these individual skills. The guides form the foundation of a sound communication curriculum and are offered as a starting point for programme directors, facilitators and learners at all levels. We describe how these guides can also be used on an everyday basis to help facilitators teach and students learn within the experiential methodology that has been shown to be central to communication training. The learner-centred and opportunistic approach used in communication teaching makes it difficult for learners to piece together their evolving understanding of communication. The guides give practical help in countering this problem by providing: an easily accessible aide-mémoire; a recording instrument that makes feedback more systematic; and an overall conceptual framework within which to organize the numerous skills that are discovered one by one as the communication curriculum unfolds.
The mitotic spindle has long been recognized to play an essential role in determining the position of the cleavage furrow during cell division, however little is known about the mechanisms involved in this process. One attractive hypothesis is that signals from the spindle may function to induce reorganization of cortical structures and transport of actin filaments to the equator during cytokinesis. While an important idea, few experiments have directly tested this model. In the present study, we have used a variety of experimental approaches to identify microtubule-dependent effects on key cortical events during normal cell cleavage, including cortical flow, reorientation of actin filaments, and formation of the contractile apparatus. Single-particle tracking experiments showed that the microtubule disrupting drug nocodazole induces an inhibition of the movements of cell surface receptors following anaphase onset, while the microtubule stabilizing drug taxol causes profound changes in the overall pattern of receptor movements. These effects were accompanied by a related set of changes in the organization of the actin cytoskeleton. In nocodazole-treated cells, the three-dimensional organization of cortical actin filaments appeared less ordered than in controls. Measurements with fluorescence-detected linear dichroism indicated a decrease in the alignment of filaments along the spindle axis. In contrast, actin filaments in taxol-treated cells showed an increased alignment along the equator on both the ventral and dorsal cortical surfaces, mirroring the redistribution pattern of surface receptors. Together, these experiments show that spindle microtubules are involved in directing bipolar flow of surface receptors and reorganization of actin filaments during cell division, thus acting as a stimulus for positioning cortical cytoskeletal components and organizing the contractile apparatus of dividing tissue culture cells.
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We have used fluorescent latex beads to label membrane receptors on cultured NRK cells. Movement of individual beads during cell division was recorded with digital imaging techniques. Surface-bound beads showed no organized movement during metaphase but started to migrate toward the equator approximately 1 min after anaphase onset, when chromosomes moved out of the equatorial region to create the interzone. The movement was most active in the central region of the cell near separating chromosomes, while beads located near the poles of the cell underwent primarily random motion. Most beads showed a surge in speed upon the passage of chromosomes, suggesting a possible link between chromosome separation and cortical reorganization. Furthermore, treatment of anaphase cells with cytochalasin D induced a rapid, simultaneous collapse of beads and cortical actin filaments into aggregates, indicating that the movement of beads was closely related to the reorganization of the actin cortex. In contrast to normal directional movement, cytochalasin-induced movement occurred in random directions and caused some beads in the equatorial region to move toward poles. Our results indicate that cytokinesis involves contractile activities, not only along the equator, but over a wide area of the actin-containing cortex. In addition, organized cortical activities appear to be temporally activated at anaphase onset, and spatially modulated by the spindle interzone or separating chromosomes.
General practitioners are often reluctant to administer brief cognitive tests, and to question the relatives of patients who appear to be demented, for fear of causing distress. Diagnoses of dementia are therefore often based on guesswork, and non-demented patients may be rated as cognitively impaired in error. A randomly selected sample of 174 general practice patients aged 80 years and over were asked to complete a simple test of orientation and information in order to assess the usefulness and acceptability of such a procedure. If patients scored 10 points or less out of 12, a relative or other knowledgeable informant was questioned about their changes in mental state and behaviour. Assessments proved acceptable to patients, relatives and doctors; diagnoses were revised in 29 cases; and practical initiatives were proposed in 15 cases. Open discussions with patients and their families proved innocuous and have much to commend them.
Primary gustatory neurons and their peripheral and central processes were evaluated histochemically in the geniculate and petrosal cranial nerve ganglia, lingual fungiform taste buds, and the nucleus of the solitary tract (NST) using 1) the plant lectin Griffonia simplicifolia I-B4, which binds specifically to D-galactose residues and selectively labels primarily nonpeptide-containing peripheral somatosensory neurons, and 2) calcitonin gene-related peptide immunoreactivity (CGRP-IR), which labels most peptidergic somatosensory neurons. Lectin reactivity was expressed by the vast majority of geniculate and petrosal ganglion cells, while CGRP-IR labeled very few cells. Peripherally, gustatory intragemmal axons penetrating fungiform taste buds were labeled only by the lectin and were depleted following chorda tympani transection. However, both lectin-labeled and CGRP-IR subpopulations of somatosensory perigemmal axons surrounding the taste buds were observed and were eliminated by section of the lingual nerve. The differing brainstem projection patterns of lectin-reactive vs. CGRP-IR central axons reflected their distinct ganglionic origins and the differential distributions of lectin reactivity and CGRP-IR among taste buds. Central lectin-reactive terminals were found throughout the entire rostrocaudal extent of the NST, including its rostral lateral "gustatory" zone; the extensive lectin-reactive visceral afferent projection can be presumed to have originated mainly from the large proportion of lectin-labeled neurons in the nodose ganglion. The lectin also prominently and selectively labeled the area postrema. CGRP-IR central terminals, however, was relatively sparse and restricted primarily to the caudal and medial "visceral" divisions of the NST. The results are discussed with respect to the possible functional implications of cell surface glycoconjugate expression by gustatory axons innervating taste bud receptor cells of the tongue.
Several plant lectins were used to characterize the cell-surface carbohydrates expressed on sensory ganglion cells and their central terminals in the spinal cord dorsal horn. In the rat, galactose-terminal glycoconjugates on a large subpopulation of small neurons whose central axons project to the substantia gelatinosa were demonstrated with the alpha-D-galactose-specific Griffonia Simplicifolia I-B4 (GSA) lectin. This neuron subset was labelled by alternative D-galactose-, N-Acetylgalactosamine-, and beta Gal(1,3)NAcGal-binding lectins. Similar GSA lectin reactivity was also illustrated in selected peripheral autonomic, gustatory and visceral sensory and enteric neurons, and the accessory olfactory bulb. The sensory neuron-specific isoenzyme, fluoride-resistant acid phosphatase (FRAP) co-localized with the GSA lectin, as did the monoclonal antibody (MAb) 2C5, which is directed against a lactoseries carbohydrate constituting a backbone structure of ABH human blood group antigens. In contrast, calcitonin gene-related peptide-immunoreactivity (CGRP-IR), used as a representative marker of peptidergic neurons, exhibited limited co-localization with GSA. A polyclonal anti-rat red blood cell (RBC) antibody co-localized with GSA, suggesting that lectin-reactive carbohydrates on rat sensory neurons are related to rat RBC antigens. In the human spinal cord, the L-fucose-binding Ulex europaeus-I (UEA) lectin also labelled the substantia gelatinosa; in rabbit, a small sensory ganglion cell subset and the spinal cord substantial gelatinosa was co-labelled by both the GSA and UEA lectins. These studies illustrate significant lectin-reactive cell surface carbohydrate expression by non-peptidergic, FRAP(+) sensory ganglion cells in the rat, and provide a means for visualizing the extensive, non-peptidergic, small sensory ganglion cell subpopulations, probably including a substantial proportion of nociceptive and unmyelinated peripheral axons.
The distribution of calcitonin-gene-related peptide (CGRP) immunoreactivity (IR) was studied in peripheral tissues of rats. The ganglionic origin, somatosensory nature, and anatomic relations of this thin-axon population were evaluated with particular emphasis on possible nociceptive roles. In animals untreated with colchicine, CGRP-IR is found in a vast proportion of small- and medium-diameter sensory ganglion cells that give rise to numerous thinly myelinated and unmyelinated axons that display CGRP-IR throughout the body. The integumentary innervation consists, in part, of an extensive subpapillary network largely traced to dermal blood vessels, sweat glands, and "free" nerve endings, some of which are found within regions containing only mast cells, fibroblasts, and collagen. Dermal papillae contain CGRP-IR axons surrounding each vascular loop; other papillary axons end freely or occasionally surround Meissner corpuscles. Intraepithelial axons enter glabrous epidermal pegs, branching and exhibiting terminals throughout the stratum spinosum. A similar pattern is found in hairy skin with additional innervation entering the base and surrounding the lower third of each hair follicle, but apparently not supplying sebaceous glands and arrector pili muscle. Axons innervating nonkeratinized oral epithelium are similar or greater in number and distribution compared to epidermis, often with more extensive branching. The high density of intraepithelial CGRP-IR innervation does not appear to correlate with the sensitive mechanoreceptor-based increase in spatial sensory discriminative capacities in the distal portions of the limb. In deep somatic tissues, CGRP-IR is principally related to vasculature and motor end plates of striated muscle, but there is an extensive network of thin axons within bone, principally in the periosteum, and focally in joint capsules, but not in relation to muscle spindles or tendon organs. These findings, together with the distribution in cranial tissues described in an accompanying paper (Silverman and Kruger: J. Comp. Neurol. 280:303-330, '89), are considered in the context of a "noceffector" concept incorporating the efferent role of these sensory axons in various tissues. It is suggested that involvement in tissue maintenance and renewal during normal function, as well as following injury, may predominate over the relatively infrequent nociceptive role of this peptidergic sensory system.
The distribution of calcitonin-gene-related peptide-like immunoreactivity (CGRP-IR) was studied in sections of decalcified rat head and selected whole-mount preparations in order to address the complex peptidergic innervation patterns in peripheral cephalic specialized zones and to examine neuronal ganglia in situ. Labeled neuron somata in trigeminal, glossopharyngeal, and vagal ganglia comprised a large proportion of small to medium size type B ganglion cells. Parasympathetic ganglia (ciliary, otic, sphenopalatine, submandibular) revealed a small population of labeled somata and numerous perisomatic IR axons, whereas sympathetic ganglion cells (superior cervical) were devoid of label though richly innervated by perisomatic IR axons. The gustatory geniculate ganglion contained only a few labeled neurons and axons. Coarse peripheral CGRP-IR axons were traced to skeletal muscle motor end plates (e.g., lingual, tensor tympani, etc.), and thin sensory axons most densely innervated the cornea, iris, general integument, all mucosal epithelia lining the tympanic, nasal, sinus and oropharyngeal cavities, and the cerebral meninges. Blood vessels, glands, ducts, and their orifices were often heavily innervated, and specific specializations and exceptions are discussed. Distinctive patterns of IR innervation characterized the various specialized sensory systems, including 1) cochlear and vestibular hair cells; 2) lingual, palatal, oropharyngeal, and laryngoepiglottal taste buds; 3) main olfactory epithelium and axons projecting to glomeruli in specific sectors of main olfactory bulb; 4) septal-olfactory organ; 5) vomeronasal organ; and 6) the nervus terminalis system. Secretory epithelia (ciliary body, choroid plexus, and stria vascularis) were notably lacking in CGRP-IR. Despite the multiplicity of functionally distinct CGRP neuronal and axonal populations, certain generalizations merit consideration. The extensive innervation of chemosensory nasal and oral epithelia may contribute to specific chemical sensitivities (e.g., relating to olfactory and gustatory senses) as well as evoking "nociceptive" responses to chemical irritants as part of a "common chemical sense." An efferent role for some of these peptidergic afferent axons may also be inferred from their specific distributions. Sites involved in regulating access to and sensitivity of sense organs to external stimuli (e.g., cochlear and vestibular hair cells, taste bud orifices, and main olfactory epithelium) are heavily innervated. Other IR axons are in position to exert control over airflow through nasal turbinates, glandular secretion, blood circulation, and duct transport systems.(ABSTRACT TRUNCATED AT 400 WORDS)
Fluoride-resistant acid phosphatase (FRAP) activity as characterized in rat and mouse was studied in sensory ganglion and spinal cord of several mammals, using both the Gomori lead-ion capture and azo-dye coupling methods. FRAP was specifically localized to small- and medium-diameter primary afferent neurons and inner substantia gelatinosa of all nonrodent animals studied, including rabbit, cat, dog, monkey, cow, and human. In rabbit, sciatic nerve transection resulted in depletion of enzymatic activity in ipsilateral spinal cord dorsal horn in a pattern corresponding to the distribution of central terminals of the nerve. Further analysis of the substrate specificity and pH dependence of FRAP was carried out primarily in rat sensory ganglion and spinal cord; the enzyme was found to hydrolyze a wide variety of phosphomonoesters in a relatively nonselective manner at both pH 5 and pH 7, including 5'-nucleotides, phosphorylated amino acids, and several exogenous compounds. The visualization of FRAP-like activity in several nonrodent species is discussed with reference to previous work indicating its presence only in mouse and rat. Technical factors are considered that limit the applicability of the lead-ion histochemical method in demonstration of FRAP and in efforts at functional characterization of the enzyme, especially in light of its ability to hydrolyze a broad spectrum of substrates over a wide pH range. Alternative interpretations of the expression of acid phosphatase activity in a select class of small sensory ganglion cells are suggested, including several possible non-synaptic roles of FRAP in the peripheral nervous system.
As part of a program to explore patterns of innervation by nociceptor-related thin sensory axons in a variety of peripheral regions, we have labeled calcitonin gene-related peptide immunoreactive (CGRP-IR) nerve fibers in whole mounts of rat testicular tunica vasculosa and cornea. Efforts were undertaken to visualize the numerically significant fluoride-resistant acid phosphatase (FRAP)-containing axon population, whose peripheral endings have heretofore remained undemonstrable due to technical limitations of currently available acid phosphatase methods. Various histochemical markers that colocalize with FRAP in dorsal root ganglion (DRG) and spinal cord were examined, and a plant lectin, Griffonia simplicifolia I-B4, has been identified that not only selectively labels FRAP(+) sensory ganglion cells and central terminals in spinal cord, but also differentially stains a large number of thin axons in testicular and corneal whole mounts. Slender lectin-labeled fibers are abundant in cornea, and are distributed throughout tunica vasculosa preparations unrelated to blood vessels. CGRP-IR axons, in contrast, maintain close adherence to vascular patterns and are more coarse and varicose in appearance. Lectin staining therefore provides the first practical and specific method for visualization of peripheral FRAP(+) axons consisting principally of sensory C fibers but possibly including a small number of unmyelinated autonomic axons. It should now be feasible, using individual whole-mount preparations from various peripheral nociceptor-innervated tissues, to examine the distributions of both peptidergic and FRAP(+) fibers, which together comprise the vast majority of thin sensory axons. It may then be possible to correlate the observed anatomical patterns with knowledge regarding properties of corresponding physiologically characterized receptive fields.
Calcitonin gene-related peptide (CGRP) is a recently characterized neuroactive substance that is expressed in a large proportion of small- to medium-diameter sensory ganglion neurons whose central terminals lie in the superficial spinal and medullary dorsal horn. This restricted distribution within the peripheral nervous system suggests a prominent role for the peptide in nociceptive processing. The mammalian tooth pulp, which receives a relatively homogeneous afferent input from thin (putative nociceptive) fibers originating from this subpopulation of trigeminal ganglion cells, thus affords an ideal target zone in which to examine peripheral nociceptive mechanisms. The large percentage of these neurons displaying CGRP-like immunoreactivity (CGRP-LI) furthermore provides a valuable tool to study its thin-fiber afferent innervation. CGRP-LI has been localized within intact, decalcified specimens of rat, cat, monkey, and human teeth and associated dental structures. A remarkably robust CGRP-LI innervation of molar pulp and dentin was revealed in all species, with fibers coursing both in fascicles and individually, in variable relation to blood vessels and pulpal stroma. Our methods enabled tracing of a large number of axons through Raschkow's plexus and odontoblast layer into dentinal tubules. Paralleling anterograde axonal transport studies, a greater share of fibers was found in coronal vis-à-vis radicular dentin. In the rat, this fiber pattern stood in contrast both to incisor dentin, which appeared devoid of CGRP-LI, and to the abundant labeled axons in gingiva and periodontal tissues. Surgical deafferentation of rat mandible resulted in widespread depletion of CGRP-LI, while superior cervical ganglionectomy was without effect, confirming the sensory nature of the CGRP-LI fibers. Neonatal capsaicin treatment greatly attenuated the immunostaining, providing evidence for CGRP-LI localization in chemosensitive unmyelinated afferents. The great density of CGRP-LI axons demonstrated is considered in contrast to the restricted range and extent of sensory stimuli to which teeth are presumably subjected, and in relation to the diverse ongoing trophic, regulatory, and reparative processes in tooth structures. It is therefore suggested that these fibers may be subserving prominent efferent roles in dental pulp not directly related to nociception.
The fluorescent dyes True Blue, Fast Blue, Nuclear Yellow and SITS were used to examine the connections of the rat brainstem sensory trigeminal nuclear complex (nV). Particular attention was paid to the following questions: do individual trigeminal neurons project to multiple targets via axon collaterals; and do primary afferent inputs to the various regions of nV arise from individual cells? Pairs of injections, using contrasting dyes, were made into the following target area combinations: ventrobasal thalamus-ipsilateral superior colliculus, cerebellum-contralateral thalamus, nucleus principalis of nV-contralateral thalamus, and nucleus principalis of nV-subnucleus caudalis of spinal nV. In general, numerous neurons throughout all subdivisions of nV and within the trigeminal ganglion were labeled by a single dye following the injections. In addition, many cells in a similar distribution were found to be doubly-labeled following such injection combination. These data demonstrate the existence of significant subpopulations of first- and second-order neurons that project to multiple targets via divergent axonal ramifications throughout the rat sensory trigeminal system.
This study was undertaken to examine whether implanting pellets of horseradish peroxidase (HRP), rather than injecting an aqueous solution, would improve the sensitivity of the retrograde tracing method as applied to infant rat neocortex. From 1 to 10 pellets, each containing approximately 10 microgram of HRP, were implanted into somatosensory cortex of 6-day-old rats. Implantation of one pellet labeled 4 neuronal groups; 5 pellets, 37 groups. Higher doses of injected HRP (20--50 microgram and 200-400 microgram) are needed to label the same number of groups. Also, individual neurons of a group generally contain more granules/cell after pellets than following injections of much higher doses of HRP. The pellet implant technique offers a high degree of reproducibility and is technically simpler than injections. We conclude that HRP pellet implants offer advantages over injections in identifying potential afferents to immature neocortex.
HRP was injected into somatosensory cortex of rats 2-8 days of age. In locus coeruleus, ipsilateral to the injection, neuronal somata were retrogradely labeled. A few neurons located in the region of cranial nerve VII, ipsilaterally, were also labeled and may represent neurons from cell group A5. No other cell groups in mid- and hindbrain contain labeled cells. The labeled cell bodies are likely to represent a major source of brainstem afferents to infant neocortex, demonstrated by other workers. Since these cell bodies are located amidst known catecholaminergic neurons, it is proposed that these neurons give rise to the monoaminergic (MA) pre-synaptic cortical inputs that have been described using ultrastructural cytochemical techniques.