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Biomedical subjects

J B Snow

Publications and source records attributed to J B Snow.

At least 37 records · Page 2Linked to original sources
PubMed1988

Effects of laser irradiation on immature olfactory neuroepithelial explants from the rat.

The photobiological effect of low-output laser irradiation on the maturation and regeneration of immature olfactory bipolar receptor cells of the rat was studied. The maturation and regeneration of the receptor cells of rat fetuses were quantified in neuroepithelial explants with morphometric analysis. The number of explants with outgrowth and the number and length of neuritic outgrowths were determined on a regular basis for 12 days. Explants in the experimental group were irradiated with a helium-neon laser using different incident energy densities (IED). Explants in the fluorescent light control group were exposed to fluorescent light for the same periods of time as those in the experimental group were exposed to laser irradiation. Explants in another control group were not exposed to laser or fluorescent light irradiation. The IED of 0.5 J/cm2 laser irradiation has been found to increase significantly the number of explants with outgrowth and the number and length of the outgrowths. Other laser IEDs or fluorescent light irradiation did not influence maturation or regeneration.

Animals↗
PubMed1988

Surgical management of head and neck cancer.

The management of advanced carcinoma of the head and neck excluding thyroid carcinoma requires a combination of operation and radiation therapy to give the patient the best chance of cure. It is not appropriate to try to extirpate advanced squamous cell carcinoma by operation alone. There is evidence that postoperative radiation therapy is more effective in local regional control at least in certain sites than preoperative radiation therapy and there is better patient acceptance of the treatment plan in which the radiation therapy is administered after the operation.

Carcinoma, Squamous Cell↗
PubMed1987

Projections from the ventral tegmental area to the olfactory tubercle in the rat.

The projection between the ventral tegmental area (VTA) and the olfactory tubercle (OT) was examined electrophysiologically in the rat. Stimulation of the olfactory bulb (OB) determined if the OT neurons were olfactory-related. Ipsilateral VTA stimulation produced a change in neuronal activity in 77% of the neurons tested, with 41% being inhibited, 24% excited, and 12% had mixed response. Contralateral VTA stimulation produced changes in only 38%. Intravenous administration of haloperidol was used in examination of the role of dopamine in this neural connection. The results suggest that the VTA-induced inhibitory response on OT neurons is mediated by dopamine, whereas excitatory responses are not. The VTA inhibitory influence projects primarily to olfactory-related neurons, since 60% of olfactory-related OT neurons were inhibited--as compared to 34% of non-olfactory-related neurons. This study documents electrophysiologically the VTA-OT connection and suggests that the dopaminergic input may modulate olfactory information projected to the OT from the OB. It also supports the concept that the OT acts as an integration center in central olfactory processing.

Animals↗
PubMed1987

Pulsatile tinnitus.

Tinnitus is a frequent presenting symptom. Tinnitus that is rhythmic and synchronous with the patient's heartbeat is rare. Pulsatile tinnitus may be the only symptom of life-threatening and treatable diseases. The presence of hearing loss or vertigo focuses the diagnostic evaluation. The cause of pulsatile tinnitus may be found on otoscopic examination. Audiologic assessment and enhanced computed tomography often contribute to the diagnosis. Increased intracranial pressure should be excluded with a fundoscopic examination. Arteriography is required to diagnose life-threatening and treatable lesions in the presence of normal otoscopy, audiologic assessment, and enhanced computed tomography.

Adult↗
PubMed1986

Olfactory evoked potentials in the rat.

Routine clinical assessment of the integrity of the olfactory pathway using olfactory evoked potentials remains an elusive goal. One important difficulty arises from the uncertainty of the exact origin of the potentials: are they produced by olfactory or trigeminal elements? To resolve this problem, an animal model using the rat was developed. Amylacetate was used as an odorant stimulus, and potentials were measured and computer averaged after elimination of trigeminal and vomeronasal activity. A positive-negative wave was recorded from the olfactory bulb surface, and a negative wave often followed by a positive wave was recorded from the surface of the cerebral cortex. Measurements from the scalp surface gave comparable results. Lesioning experiments of the olfactory pathway indicate that the evoked potentials recorded at the vertex originate in the ventral forebrain, specifically in the prepyriform cortex, olfactory tubercle, and anterior olfactory nucleus.

Animals↗
PubMed1985

Olfactory marker protein in the human olfactory pathway.

The presence of olfactory marker protein (OMP) in the olfactory tissue of rats, gerbils, and humans was demonstrated with goat antiserum to rat OMP. In control studies on rat neural tissue, OMP was found to be located in the olfactory receptor cells, nerves, and bulbs. Likewise, staining of OMP was found in the olfactory tissues of gerbils. Olfactory marker protein reactivity was also demonstrated in human olfactory receptor cells, nerves, and bulbs. The reactivity of OMP in human olfactory neurons to goat antiserum has allowed determination of the exact junction of olfactory and respiratory epithelia immunohistochemically.

Aged↗
PubMed1985

A possible site of production of the negative endocochlear DC potential.

The scala vestibuli or the scala tympani of guinea pigs was perfused with artificial perilymph containing 1, 5, 10, 20, 30, 40 and 50 mM of potassium chloride in a total concentration of 150 mM with the background composed of sodium chloride. With the perfusion of the scala vestibuli, each concentration failed to alter the magnitude of the negative endocochlear DC potential produced by anoxia or the intravenous injection of 100 mg/kg of body weight of furosemide. With the perfusion of the scala tympani, the negative endocochlear DC potential disappeared precipitously and the maximum output of the cochlear microphonic was severely depressed with concentrations of potassium chloride of 30 mM or greater. The magnitude of the negative endocochlear DC potential appears to be closely related to the maximum output of the cochlear microphonic. These results suggest that the site of production of the negative EP is in the hair cells of the organ of Corti.

Animals↗
PubMed1985

Immunohistopathologic analysis of olfactory degeneration caused by ischemia.

The development of olfactory dysfunction caused by ischemia was studied in Mongolian gerbils. Mongolian gerbils frequently have an anomaly of the cerebral circulation and are susceptible to brain ischemia or infarction following ligation of a single common carotid artery. Ischemia was induced by unilateral common carotid artery ligation or temporary occlusion of both common carotid arteries, and the olfactory pathway was examined. In the olfactory pathway of the forebrain, ischemic changes were observed in the lateral olfactory tract, olfactory tubercle, olfactory ventricle, and anterior olfactory nucleus. The olfactory bulb was resistant to ischemia. Partial or complete degeneration of the ipsilateral olfactory neuroepithelium was observed in some gerbils that survived more than 14 days after the onset of ischemia. Immunohistopathologic analysis of the neuroepithelium for the olfactory marker protein revealed that functional damage of the olfactory neurons occurred in some gerbils within the first few days after the ischemic event.

Animals↗
PubMed1985

Immunohistopathology of human olfactory epithelium, nerve and bulb.

The immunohistochemical characteristics of the human olfactory system were (OMP). OMP was detected in the olfactory receptor neurons and processes extending from the olfactory neuroepithelium to the olfactory bulb. The olfactory receptor cells located close to the epithelial surface also contained OMP. In severely degenerate regions, only a few OMP-containing cells were observed. Differences in OMP-staining intensity were noted among the olfactory receptor cells. The thick neuroepithelium. Proliferating olfactory neuroepithelium contained OMP reactive and nonreactive olfactory receptor cells. The presence of OMP reactive and nonreactive olfactory neurons indicates the coexistence of two functionally different phases of olfactory neurons. These findings suggest that continuous cell turnover is occurring in human olfactory neuroepithelium.

Adult↗
PubMed1984

Positional vertigo.

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMed1984

Structure of human fetal and adult olfactory neuroepithelium.

Human olfactory neuroepithelium and respiratory mucous membrane in fetal and adult whole-mount sections were studied. In the fetus, the olfactory neuroepithelium extends from the roof of the nasal cavity to the midportion of the nasal septum and onto the superior turbinate in a continuous fashion. In the adult, the zonal distribution of supporting, sensory receptor, and basal cells is frequently disrupted, and the supporting and sensory receptor cells are often depleted or degenerate. The degree of the degeneration of the adult olfactory neuroepithelium varies from case to case. The most striking feature in the adult is the replacement of large areas of olfactory neuroepithelium with respiratory epithelium. The extensive replacement of olfactory neuroepithelium with respiratory epithelium points out the sampling problem related to small, random biopsy specimens of the olfactory area.

Adult↗
PubMed1984

Histopathology of the olfactory pathway due to ischemia.

Various agents, such as trauma, viral infections and neoplasms cause olfactory dysfunction. However, little is understood concerning the role of ischemia. An experimental model of brain ischemia was developed in the Mongolian gerbil, and the olfactory pathway was studied. This animal was chosen because of its incomplete circle of Willis, since poor patency of the circle of Willis is not an uncommon finding in the aging human. Ischemia was induced by unilateral ligation of one common carotid artery or temporary occlusion of both common carotid arteries. Under both circumstances, ischemic changes occurred in the lateral olfactory tract, the olfactory ventricle, and the olfactory tubercle. Damage is more severe with bilateral temporary occlusion than unilateral ligation. The olfactory bulbs and neuroepithelium, however, are resistant to ischemia.

Animals↗
PubMed1984

Diagnosis and therapy for acute laryngeal and tracheal trauma.

A laryngeal fracture should be suspected when there is hemoptysis and subcutaneous emphysema following blunt injury to the neck. Computed tomography of the neck should be used to define the extent of the injury. Cervical vertebral fractures and dislocations, perforation of the pharynx and esophagus, and vascular injuries must be excluded. Establishment of a secure airway by tracheotomy, avoidance of flexion or extension of the neck until cervical vertebral injuries are excluded, and evaluation for recurrent laryngeal paralysis are of great importance. The repair of the fractured larynx requires prompt repair of lacerations of the mucous membrane, reduction of cartilaginous fractures, and internal splinting for six weeks. Anastomosis of the transected trachea is carried out prior to repair of the recurrent laryngeal nerve injury. Although suturing of the transected nerve is controversial, there is general agreement that implantation of the avulsed recurrent laryngeal nerve in the posterior cricoarytenoid muscle is appropriate.

Humans↗
PubMed1984

Surgical therapy for vocal dysfunction.

In general, misuse and abuse of the voice in the form of using the voice too loudly and too long and affecting a fundamental frequency that is too low produce chronic changes in the lamina propria while inhalation of irritants produces changes in the epithelium of the true vocal cords. Voice therapy plays an essential role in the preoperative and postoperative management of the patient. The use of the operative microscope under general anesthesia has permitted the regular preservation of the external elastic lamina, which is necessary for the restoration of the voice to its full dynamic and frequency ranges. Resection of the left recurrent laryngeal nerve is of great value in the treatment of spastic dysphonia. In the paralyzed larynx, injection of Teflon paste is of proven value in restoring the voice in permanent unilateral recurrent laryngeal nerve paralysis. Reinnervation procedures for unilateral and bilateral recurrent laryngeal nerve and superior laryngeal nerve paralysis must at this time be considered developmental.

Child↗