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D V Smith

Publications and source records attributed to D V Smith.

At least 55 records · Page 3Linked to original sources
PubMed1992

Hardware and software requirements for a picture archiving and communication system's diagnostic workstations.

Electronic systems (picture archiving and communications systems [PACS]) for image and multimedia data distribution, archiving, and transmission, represent the future of radiology. The workstation is the point of contact between a PACS and the radiologist or referring physician. Therefore, the acceptance of PACS is highly dependent on workstation functionality and performance. This paper, based on our experience in evaluating commercial workstations and on a review of recent literature, describes hardware and software requirements for diagnostic workstations that could be used for making primary diagnoses in a radiology department. Requirements for PACS workstations for use in referring clinics are also briefly described. These workstations must be able to handle the large volume of images to be viewed efficiently, add new functionality to improve the productivity of physicians, technologists, and other health care providers, and provide enough flexibility to allow the electronic systems to grow as medical imaging technology evolves.

Computer Systems↗
PubMed1992

Office management of taste and smell disorders.

Chemosensory disorders have been receiving increasing clinical attention but remain a difficult diagnostic problem. With the development of several well-standardized testing methods, taste or smell loss can now be verified, and this has added to knowledge concerning the common causes of dysfunction. Diagnosis typically rests upon the history and physical examination, but, except in the case of obstructive nasal and sinus pathologic conditions, therapy usually remains elusive.

Ambulatory Care↗
PubMed1991

Taste reactivity in the hamster.

Taste reactivity, which was first described in the rat, consists of ingestive and aversive response components, the latter seen mostly to bitter-tasting stimuli. The present experiment characterized the hamster's taste reactivity to an array of stimuli (sugars: 1 M sucrose, d-fructose and d-glucose; sodium salts: 1 M NaCl, Na2SO4 and NaNO3; acids: 30 mM HCl, tartaric acid and citric acid; bitter-tasting stimuli: 100 mM quinine hydrochloride and nicotine sulfate and 10 mM denatonium benzoate). These 12 stimuli were chosen to represent 3 examples each of stimuli that taste sweet, salty, sour, or bitter to humans; they were presented in random order via an intraoral fistula, one stimulus each day per animal (n = 10). Infusions of 0.6 ml were delivered over a 1-min period from a syringe pump. Orofacial and somatic motor responses were recorded on videotape for later analysis and were also coded online into a computer. Ingestive responses included forward and lateral tongue protrusions and aversive responses included gaping, chin rubbing, forelimb flailing, fluid rejection, increased locomotion, and aversive posturing. Each stimulus group produced a characteristic pattern of these behaviors, with sugars eliciting only ingestive behaviors and the bitter stimuli evoking predominantly aversive responses. Both sodium salts and acids produced ingestive responses, as seen previously in the rat, although these stimuli also elicited aversive behaviors in the hamster, including apes. The patterns of responses were characterized using multivariate procedures; the stimuli fell into distinct groups that were separated primarily along an hedonic dimension.

Animals↗
PubMed1991

Organization of gustatory sensitivities in hamster superior laryngeal nerve fibers.

1. Mammalian taste receptors are distributed within several distinct subpopulations, innervated by branches of cranial nerves VII, IX, and X. Most gustatory electrophysiology has focused on input from the fungiform papillae on the anterior portion of the tongue, carried by the chorda tympani branch of the VIIth nerve. However, laryngeal taste buds in the hamster are as numerous as those in the fungiform papillae. Gustatory fibers in the hamster's chorda tympani and glossopharyngeal nerves have been well characterized. In comparison with these taste fibers, much less is known about the chemical sensitivities of fibers innervating laryngeal taste buds. 2. Action potentials were recorded from 65 individual fibers in the superior laryngeal nerve (SLN) of the hamster. Stimuli were distilled H2O and five concentrations each of sucrose, NaCl, HCl, and quinine hydrochloride (QHCl). All stimuli except the NaCl series were made in physiological saline (0.154 M NaCl) and were delivered from the laryngeal side of the epiglottis via a tracheal cannula. Responses were quantified as the number of impulses in 10 s minus the responses in the preceding 10 s of baseline activity during a rinse with physiological saline. 3. Distilled H2O, HCl, and NaCl were by far the most excitatory stimuli, with mean responses across all cells 5-10 times greater than those evoked by sucrose or QHCl. The order of effectiveness of the strongest concentrations of the stimuli was H2O greater than 0.03 M HCl greater than 1.0 M NaCl much greater than 0.03 M QHCl greater than 1.0 M sucrose. 4. The mean concentration-response function for NaCl was U shaped, with the greatest number of impulses to distilled H2O and 1.0 M NaCl. The responses diminished as the concentrations approached physiological levels (0.154 M NaCl), where there was no response, and increased as NaCl concentration rose above this level. Increasing concentrations of HCl above 0.0003 M elicited increasing responses in these fibers. 5. The mean time course of the responses to distilled H2O and to hypotonic NaCl solutions (0.01 and 0.03 M) peaked in the first few seconds and then declined slowly. This was distinct from the time course of the responses to hypertonic NaCl concentrations (0.3 and 1.0 M), which increased gradually throughout the 10-s response period. Responses to HCl peaked in the initial second and then decayed rapidly to a slowly declining plateau. These distinctively different time courses suggest different receptor mechanisms for water, salt, and acid stimuli. 6. The across-fiber pattern of the responses to hypotonic NaCl solutions correlated strongly to that elicited by distilled H2O.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1990

Postnatal development of palatal and laryngeal taste buds in the hamster.

Mammalian taste buds are distributed within several distinct subpopulations, innervated by branches of three cranial nerves. These taste bud populations originate and mature at different times in various mammalian species and are thought to play differential roles in the control of taste-mediated behaviors. The hamster is a common animal for the electrophysiological study of the gustatory system, and it has been shown that taste buds innervated by the IXth nerve develop postnatally in this species. To delineate further the development of the gustatory system of hamsters, we quantified the number of taste buds appearing on the palatal, nasopharyngeal, and laryngeal epithelium from birth through 120 days of age. Taste buds are present in almost adult numbers on the soft palate at birth, but only 39% of these are mature. Distinct taste pores, indicative of mature taste buds, increase in number until about 20-30 days of life, at which time all of the taste buds on the soft palate and on the nasoincisive papillae are fully developed. Taste buds are concentrated primarily on the posterior and medial portions of the soft palate. Taste buds located on the laryngeal surface of the epiglottis and the aryepiglottal folds are absent at birth and originate and mature over the following 120 days. Laryngeal taste buds are more concentrated on the aryepiglottal folds than on the epiglottis. On the soft palate and in the epiglottal region, the maturation of taste buds is well characterized by a logarithmic function (Y = a log X + B) relating the number of mature taste buds to postnatal age. On the soft palate, the length of the taste buds from base to apex correlates with the thickness of the epithelium, which increases with development. The diameter of mature taste buds on the soft palate does not change with age. In contrast to many mammalian species, in rodents taste bud development occurs mostly after birth. Rapid postnatal development progresses at a time when ingestive behavior is undergoing a number of significant changes. Taste buds in the larynx have been implicated in a number of laryngeal reflexes (i.e., apnea, swallowing) in several nonrodent species. The electrophysiological properties of superior laryngeal nerve fibers would suggest a similar function for epiglottal taste buds in the hamster.

Animals↗
PubMed1989

Gustatory innervation in the rabbit: central distribution of sensory and motor components of the chorda tympani, glossopharyngeal, and superior laryngeal nerves.

Although rabbits have been used extensively in neurophysiological studies of the gustatory system, there is little information about the anatomical organization of taste in this species. Afferent and efferent central connections of three nerves innervating oral or laryngeal taste buds in the rabbit, including the chorda tympani (CT), the lingual-tonsillar branch of the glossopharyngeal (IX), and the superior laryngeal nerve (SLN), were traced by means of horseradish peroxidase neurohistochemistry. After entering the brainstem, most afferent fibers of CT, IX, and SLN turned caudally in the solitary tract, with fibers of the CT terminating in the nucleus of the solitary tract from 1.0 mm rostral to 3.8 mm caudal to the caudal border of the dorsal cochlear nucleus. There was terminal label from the CT also in the principal trigeminal nucleus. There was terminal label from the CT also in the principal trigeminal nucleus and the oral and intermediate divisions of the spinal trigeminal nucleus. Preganglionic parasympathetic cell bodies of the superior salivatory nucleus were labeled retrogradely in the reticular formation ventral to the rostral pole of the solitary nucleus. Afferent fibers of the IXth nerve terminated in the solitary nucleus from 0.6 mm rostral to 5.0 mm caudal to the caudal border of the dorsal cochlear nucleus. There were also labeled terminals in the principal trigeminal nucleus and in all three divisions of the spinal trigeminal nucleus. Cell bodies composing the inferior salivatory nucleus were labeled in and around the solitary nucleus and subadjacent reticular formation just rostral to the caudal border of the dorsal cochlear nucleus. There were also a few lightly labeled cells within the nucleus ambiguus at its most rostral extent. Afferent fibers of the SLN terminated in the solitary nucleus from 1.2 to 6.8 mm caudal to the dorsal cochlear nucleus. There was also some terminal label in the intermediate and caudal divisions of the spinal trigeminal nucleus. Many cells were retrogradely labeled in the nucleus ambiguus following application of HRP to the SLN and a few cells were labeled in and around the solitary nucleus just caudal to the dorsal cochlear nucleus. These three nerves show an overlapping rostral to caudal distribution of afferent input within the nucleus of the solitary tract that may be related to their gustatory and visceral functions.

Animals↗
PubMed1988

Response properties of fibers in the hamster superior laryngeal nerve.

The purpose of the present investigation was to record electrophysiological responses from single fibers in the hamster superior laryngeal nerve (SLN) that were responsive to chemical stimulation of the larynx. Twenty chemical solutions, commonly used in studies of mammalian gustatory physiology, were applied to taste buds on and around the epiglottis. These stimuli were dissolved in physiological saline. Responses were the number of impulses elicited over a 15-s period following stimulus onset, above or below the background activity elicited by a previous rinse with saline. Unlike fibers in the hamster chorda tympani or glossopharyngeal nerves, SLN units were not easily classifiable into response types. Excitatory stimuli were primarily acids and bitter-tasting stimuli, with the order of their effectiveness being urea much greater than tartaric acid greater than HCl greater than KCl greater than citric acid greater than caffeine greater than quinine hydrochloride greater than acetic acid. The sweet-tasting stimuli and most salts other than KCl were primarily inhibitory, with the order of inhibitory effectiveness being CaCl2 greater than sucrose greater than fructose greater than LiCl greater than NaNO3 greater than Li2SO4 greater than NaCl. A hierarchical cluster analysis of fibers yielded no distinct clusters, yet differing sensitivities across the fibers were suggested. SLN fibers are highly responsive to sour and bitter stimuli, although they are not sensitive to fine differences in taste quality, as are fibers in other gustatory nerves.

Action Potentials↗
PubMed1988

The organization of taste sensibilities in hamster chorda tympani nerve fibers.

Electrophysiological measurements of nerve impulse frequencies were used to explore the organization of taste sensibilities in single fibers of the hamster chorda tympani nerve. Moderately intense taste solutions that are either very similar or easily discriminated were applied to the anterior lingual surface. 40 response profiles or 13 stimulus activation patterns were considered variables and examined with multivariate statistical techniques. Three kinds of response profiles were seen in fibers that varied in their overall sensitivity to taste solutions. One profile (S) showed selectivity for sweeteners, a second (N) showed selectivity for sodium salts, and a third (H) showed sensitivity to salts, acids, and other compounds. Hierarchical cluster analysis indicated that profiles fell into discrete classes. Responses to many pairs of effective stimuli were covariant across profiles within a class, but some acidic stimuli had more idiosyncratic effects. Factor analysis of profiles identified two common factors, accounting for 77% of the variance. A unipolar factor was identified with the N profile, and a bipolar factor was identified with the S profile and its opposite, the H profile. Three stimulus activation patterns were elicited by taste solutions that varied in intensity of effect. Hierarchical cluster analysis indicated that the patterns fell into discrete classes. Factor analysis of patterns identified three common unipolar factors accounting for 82% of the variance. Eight stimuli (MgSO4, NH4Cl, KCl, citric acid, acetic acid, urea, quinine HCl, HCl) selectively activated fibers with H profiles, three stimuli (fructose, Na saccharin, sucrose) selectively activated fibers with S profiles, and two stimuli (NaNO3, NaCl) activated fibers with N profiles more strongly than fibers with H profiles. Stimuli that evoke different patterns taste distinct to hamsters. Stimuli that evoke the same pattern taste more similar. It was concluded that the hundreds of peripheral taste neurons that innervate the anterior tongue play one of three functional roles, providing information about one of three features that are shared by different chemical solutions.

Animals↗
PubMed1988

Gustatory responsiveness of fibers in the hamster glossopharyngeal nerve.

1. Mammalian taste receptors are distributed within separate subpopulations, innervated by branches of cranial nerves VII, IX, and X. Most gustatory electrophysiology has focused on input from the fungiform papillae on the anterior portion of the tongue, carried by the chorda tympani branch of the VIIth nerve. However, only a small percentage of the taste buds are located in the fungiform papillae (approximately 18% in the hamster). There have been no studies on the hamster's IXth nerve, which innervates greater than 50% of its taste buds, and most other studies of IXth nerve function have employed only whole-nerve recording. 2. Action potentials were recorded from 83 individual fibers in the IXth nerve of the hamster. Stimuli were five concentrations each of sucrose, NaCl, HCl, and quinine hydrochloride (QHCl), all presented to every fiber at 37 degrees C. Responses were quantified as the number of impulses in 10 s minus the preceding 10 s of spontaneous activity. 3. Across these concentration series, HCl and QHCl were by far the most excitatory stimuli, with mean responses across all cells three to four times greater than those evoked by sucrose or NaCl. The order of effectiveness of the stimuli was H greater than Q much greater than N greater than S. 4. Of the 83 fibers, 56 were stimulated via the foliate papillae and 27 via the single vallate papilla. No fibers responded to both of these fields. There were generally no differences in the sensitivity of these two subpopulations of taste buds, except that QHCl was more effective when applied to the foliates. 5. A "total" response measure was derived by summing the excitatory responses to each stimulus across the entire concentration series. The fibers were then classified according to the best total response, resulting in 52 HCl-, 19 QHCl-, 8 sucrose- and 4 NaCl-best cells. Considering the slope of the concentration-response functions as a criterion for classification produced very similar results. The fiber classification varied somewhat with concentration, with more fibers categorized as HCl- and QHCl-best at the higher concentration levels. 6. Breadth of responsiveness was measured using the equation developed by Smith and Travers. At the concentrations used to examine hamster chorda tympani fibers, IXth nerve fibers were not very responsive and were quite narrowly tuned to the four taste qualities. At higher concentrations the fibers became more broadly responsive across the four stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1988

Assessment of patients with taste and smell disorders.

The evaluation of patients with taste and smell complaints is difficult without standardized quantitative methods of assessment. This paper summarizes recent developments in the evaluation of chemosensory patients. Evaluation must begin with a careful medical history, since certain questions can help in establishing an etiology. Several recent advances have been made in the development of standardized tests for the assessment of taste and olfactory function. Smell can be evaluated with a combination of butanol threshold and odor identification (University of Connecticut test battery) and with the University of Pennsylvania Smell Identification Test (UPSIT). Scores obtained from 91 patients show good correlation between these two testing procedures. Both tests provide normative data for comparison, with the UPSIT including both age- and sex-related norms. Traditional evaluation of taste deficits with threshold procedures has been questioned. Measures of suprathreshold taste intensity require the anchoring of taste judgements to another, presumably normal, modality. This has been approached using magnitude matching, in which taste and auditory loudness are judged on the same scale. Spatial testing of the tongue and soft palate can reveal pathology of the gustatory nerves or their central connections. Further understanding of taste and olfactory dysfunction will be facilitated by the development of standardized methods of evaluation.

Humans↗
PubMed1988

Proliferation of taste buds in the foliate and vallate papillae of postnatal hamsters.

The growth of the taste system in the hamster is considered in comparison to the postnatal development of other organ systems and the entire animal. No taste buds are present in vallate or foliate papillae of the hamster at birth, but they attain both the appearance and numbers of adult taste buds within 5 weeks of age. The most rapid increase in the number of taste buds occurs within the first 10 days of life, and this proliferation anticipates the weaning of hamsters which occurs by about three weeks of age. Foliate taste buds reach a maximal number within two months, but vallate taste buds continue to increase in number through 4 months of age. Taste bud proliferation and development occur earlier and more rapidly than in other organ systems. This early development of taste buds may protect the weanling hamster against accidental poisoning by noxious plants, and it may also reinforce the food intake which is required for normal growth.

Animals↗
PubMed1987

Convergence onto hamster medullary taste neurons.

Research has shown that gustatory afferents innervating different areas of the oral cavity converge onto single neurons in the nucleus tractus solitarii (NTS). However, most studies of gustatory physiology have only stimulated the receptors on the anterior tongue. No information exists on the responses of hamster NTS neurons to stimulation of receptors located in other areas of the oral cavity. The present investigation compared responses of hamster NTS neurons to stimulation of receptors on the anterior tongue and posterior oral cavity, and to stimulation of both receptor populations together. Of the neurons, 64% responded to both anterior tongue and posterior oral cavity stimulation. The remaining neurons responded exclusively to stimulation of one area. Cells responsive to both fields of stimulation were found throughout the rostral NTS. Cells responding to stimulation of only one field were anatomically separate. Most neurons (69%) were more responsive to anterior tongue than posterior oral cavity stimulation. The neural responses to stimulation of both fields simultaneously were complex. Frequently, a cell's response was intermediate between those produced by stimulation of either receptor population alone. In other cases the response was the same as the larger of the two individual responses. The breadth of responsiveness to the 4 basic taste stimuli (sucrose, NaCl, HCl and quinine-HCl) was similar for both receptor populations, but the breadth of tuning of an individual cell for one field of stimulation was not correlated with its breadth of responsiveness for the other. In contrast, the breadth of tuning following stimulation of the entire oral cavity was correlated with that following stimulation of the anterior tongue.

Action Potentials↗
PubMed1987

Multimodal responses of taste neurons in the frog nucleus tractus solitarius.

The responses of 216 neurons in the nucleus tractus solitarius (NTS) of the American bullfrog were recorded following taste, temperature, and tactile stimulation. Cells were classified on the basis of their responses to 5 taste stimuli: 0.5 M NaCl, 0.0005 M quinine-HCl (QHCl), 0.01 M acetic acid, 0.5 M sucrose, and deionized water (water). Neurons showing excitatory responses to 1, 2, 3, or 4 of the 5 kinds of taste stimuli were named Type I, II, III, or IV, respectively. Cells whose spontaneous rate was inhibited by taste and/or tactile stimulation of the tongue were termed Type V. Type VI neurons were excited by tactile stimulation alone. Of the 216 cells, 115 were excited or inhibited by taste stimuli (Types I-V), with 35 being Type I, 34 Type II, 40 Type III, 2 Type IV and 4 Type V. The remaining 101 cells were responsive only to tactile stimulation (Type VI). Of those 111 cells excited by taste stimulation (Types I-IV), 106 (95%) responded to NaCl, 66 (59%) to acetic acid, 44 (40%) to QHCl, 10 (9%) to water, and 9 (8%) to warming. No cells responded to sucrose. Of the 111 cells of Types I-IV, 76 (68%) were also sensitive to mechanical stimulation of the tongue. There was some differential distribution of these neuron types within the NTS, with more narrowly tuned cells (Type I) being located more dorsally in the nucleus than the more broadly tuned (Type III) neurons. Cells responding exclusively to touch (Type VI) were also more dorsally situated than those responding to two or more taste stimuli (Types II and III).

Action Potentials↗
PubMed1986

Central projections of the hamster superior laryngeal nerve.

The superior laryngeal nerve (SLN) is known to innervate taste buds on the epiglottis of several mammalian species. Because of an increasing interest in the physiology of the gustatory system of hamsters, the brainstem projections of the SLN were investigated in this species. Crystallized HRP was applied to the proximal portion of the cut SLN or to one of its five distal branches. Anterograde transganglionic transport of HRP revealed afferent fibers of the SLN projecting into the ipsilateral solitary tract (ST) from 0.3 to 3.0 mm caudal to the dorsal cochlear nucleus (DCN), with the major area of termination in the nucleus of the solitary tract (NST) between 0.6 and 1.6 mm caudal to DCN. Some afferent fibers crossed the midline approximately 2.0 mm caudal to DCN to terminate contralaterally within the NST. Efferent cell bodies were retrogradely labeled within the nucleus ambiguus (NA) and in and around the more rostral portions of NST. There were five identifiable distal branches of SLN, termed A1, A2, M1, M2 and P, from anterior to posterior. Afferent fibers were carried in A2 and P, whereas efferent fibers were evident in all five branches. The heaviest projection from the NA occurred in the two middle branches (M1 and M2) and that from the NST in the posterior branch (P). Afferent projections of the Xth cranial nerve, along with those from the VIIth and IXth, into the NST provide a neural substrate for the integration of sensory inputs related to a number of oral and respiratory reflexes.

Animals↗
PubMed1984

Quantitative taste bud distribution in the hamster.

The distribution of taste buds was examined in hamsters to reveal the sources of convergent neural activity on taste neurons of the medulla and pons. A total of 723 taste buds was found in adult animals. Fungiform papillae contained 130 taste buds (18%). A single vallate papilla had 168 taste buds (23%). There were 230 taste buds (32%) located on bilateral foliate papillae. The palate contained 100 taste buds (14%) divided among the soft palate (88, 12%) and the incisal papilla (12, 2%). On the epiglottis and adjacent region of the esophagus were found 70 taste buds (10%). About 10 taste buds each were located on the buccal wall (1.4%), while the remaining 5 taste buds were found on the sublingual organ. Conclusions about information processing in central neurons of the gustatory system must reflect knowledge of diverse receptor populations and their interactions.

Animals↗
PubMed1984

Conditioned taste aversions: generalization to taste mixtures.

Rats were trained to take their daily water ration within a 30-min session, during which the number of licks per 10-sec presentation of a drinking tube could be recorded. During one of these sessions, one of three stimuli (sucrose, NaCl or HCl) was presented, followed by the administration of cyclophosphamide to produce a conditioned taste aversion. When tested with mixtures of the conditioned stimulus (CS) with the other two stimuli and also with quinine hydrochloride, the animals avoided mixtures containing the CS in proportion to its concentration in the mixture. Although the natural preferences and aversions for these stimuli interacted somewhat with the learned taste aversions, rats responded to the presence of a CS in a mixture and did not generalize to other stimuli not containing the CS. Thus, the generalization of conditioned taste aversions provides a good measure of the behavioral similarities among gustatory stimuli.

Animals↗