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Biomedical subjects

J B Snow

Publications and source records attributed to J B Snow.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Combined radiation therapy and surgery in the management of advanced head and neck cancer: final report of study 73-03 of the Radiation Therapy Oncology Group.

Between March 1973 and June 1979, patients with advanced operable squamous cell carcinoma of the supraglottic larynx or hypopharynx were randomly allocated to receive either preoperative radiation therapy (5,000 rad) or postoperative radiation therapy (6,000 rad). Patients with oral cavity or oropharynx lesions were randomly assigned either preoperative radiation, postoperative radiation, or definitive radiation therapy (6,500-7,000 rad), with surgery reserved for salvage if residual disease was present 6 weeks after completion of irradiation. Three hundred twenty patients were evaluable with a median follow-up of 60 months. Based on results in 277 patients across all four regions combined, locoregional control was significantly better for patients assigned to receive postoperative radiation therapy (65%) compared with those assigned to receive preoperative radiation therapy (48%, P = 0.04). This was due to a higher rate of both persistent and recurrent local and regional disease in the preoperative group. Survival also showed a trend to be better in the postoperative group (38%) compared with the preoperative group (33%, P = 0.10). Rates of severe surgical and radiation therapy complications were similar overall. Forty-three patients were evaluable for each of the three treatment regimens assigned to patients with oral cavity or oropharynx lesions. Due to the small number of patients available for this portion of the trial, the observed differences for overall survival (4-year percentage 33% overall; 30% preoperative, 36% postoperative, 33% definitive radiation therapy) and for locoregional control (45% overall; 43% preoperative, 52% postoperative, 38% definitive radiation therapy) were not statistically significant. The use of definitive radiation therapy with surgical rescue as an ethically justified alternative treatment for these tumors remains a question for further research.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Clinical problems in chemosensory disturbances.

The clinical evaluation of patients with disorders of smell and taste has been hampered by difficulties in stimulus control and response measurement. These senses play a crucial role in food selection and enjoyment and in avoidance of danger, and they deserve the attention of the otolaryngologist as much as audition and vestibular function do. The definition of the degree of disability should be based on psychophysical measures rather than the patient's complaint. An anatomic diagnosis may facilitate the etiologic diagnosis, and it is important to attempt to differentiate transport abnormalities from sensorineural deficits, and receptor deficits from neural deficits. The common causes of smell and taste abnormalities are listed. Selected current work in the field with immediate clinical relevance is reviewed, and opportunities for basic studies that may provide needed data to improve the diagnostic evaluation of patients and to suggest therapeutic strategies for clinical trials are briefly discussed. These areas of study can be pursued with currently available technology.

Chemoreceptor Cells↗
PubMedDate not supplied

Effect of stimulation of the horizontal limb of the diagonal band on rat olfactory bulb neuronal activity.

Reports suggest that patients with Alzheimer's disease have deficient olfactory sensitivity and disruption of the cholinergic pathways. Elucidation of the cholinergic system in the olfactory bulb is essential to the understanding of this disease for diagnostic and therapeutic advances. Possible cholinergic projection to the olfactory bulb was studied in rats with transected medial forebrain bundles by stimulating the horizontal limb of the diagonal band, which contains cholinergic perikarya. Electrical stimulation of the horizontal limb of the diagonal band evoked negative potentials in the granule cell layer. Neurons in the granule cell layer were excited, and those in the mitral cell layer and external plexiform cell layer showed inhibition, often followed by excitation. These responses were attenuated by the administration of the cholinergic blocker, atropine. The role of cholinergic projection to olfactory bulb neurons is discussed.

Animals↗
PubMedDate not supplied

Dopaminergic modulation of bulbofugal projections in the rat olfactory tubercle.

Neuronal activities following olfactory bulb electrical stimulation were examined before and after administration of dopamine and dopamine antagonist in the rat olfactory tubercle. The inhibitory response to olfactory bulb stimulation was attenuated by systemic haloperidol administration, but the excitatory response to olfactory bulb stimulation rarely was modulated. Topical application of dopamine by iontophoresis extended the duration of inhibition in 56% of the neurons sampled and diminished it in 25%; the excitatory response was modulated in 42% of neurons, most of which were attenuated. These findings suggest that dopamine in the olfactory tubercle could be involved in modulations of neuronal activities related to olfactory transduction.

Animals↗
PubMedDate not supplied

Research in the auditory and vestibular systems. The recommendations of the National Institute on Deafness and Other Communication Disorders National Strategic Research Plan.

Promising fundamental research opportunities identified by the National Strategic Research Plan of the National Institute on Deafness and Other Communication Disorders include encoding of sound and gravitational/acceleration force by the inner ear, processing complex signals in the central nervous system, the molecular and cellular mechanisms responsible for hair cell motility, mechanoelectric transduction, homeostasis and metabolism of the inner ear, synaptic transmission, hair cell regeneration, plasticity and otoacoustic emissions. Clinical research opportunities include the molecular genetics of hereditary hearing impairment, the etiology of sensorineural hearing loss, environmental ototoxicity, the elucidation of tinnitus, the development of vaccines against otitis media, pharmacotherapy, rehabilitation for hearing loss and deafness with hearing aids and cochlear implants and physical therapy rehabilitation for vestibular disorders.

Biomechanical Phenomena↗
PubMedDate not supplied

Carcinoma of the nasopharynx in children.

Seven children with carcinoma of the nasopharynx have been treated and followed for five years. In this group of patients there were no cranial nerve palsies or radiographic evidence of destruction of the base of the skull. Four of the seven patients are living and well. The development of lymphoepithelioma in two siblings is of great interest from an environmental and genetic point of view. The older sibling developed the clinical manifestations of the tumor at 12 years of age and four years later the younger sibling developed them at 14 years of age. The possible etiologic relationship of carcinoma of the nasopharynx to the Epstein-Barr virus is discussed. The good survival rate in these patients under 21 years of age suggests that the prognosis in carcinoma of the nasopharynx is better in the younger age group than in adults. The management of these patients illustrates that carcinoma of the nasopharynx should be managed as a regional rather than a systemic disease. Systemic drug therapy is sometimes advocated because of confusion over the name lymphoepithelioma on the assumption that these tumors are more related to lymphomas and lymphosarcomas than carcinomas. It is clear that lymphoepitheliomas should be managed as carcinomas.

Adolescent↗
PubMedDate not supplied

Hearing loss of a central type secondary to anoxic anoxia.

The effect of anoxic anoxia on the threshold sensitivity and amplitude of the responses from the auditory cortex, inferior colliculus and cochlea to acoustic stimuli in guinea pigs was studied. Decay of the amplitude of the responses from the auditory cortex and the inferior colliculus occurs faster and is more severe than that of the cochlea. Recovery of the amplitude of the responses is slower at the auditory cortex and the inferior colliculus than at the cochlea. Loss of auditory threshold sensitivity in anoxic anoxia is most prominent at the auditory cortex. The loss of sensitivity at the inferior colliculus is the next most severe. The loss of sensitivity at the cochlea is negligible. The relative vulnerability of the central auditory pathway to anoxic anoxia as compared to the end organ is demonstrated.

Animals↗
PubMedDate not supplied

Evaluation of randomized preoperative and postoperative radiation therapy for supraglottic carcinoma. Preliminary report.

One hundred and ten patients with supraglottic squamous cell carcinoma have been randomized for preoperative radiation therapy and surgery versus surgery and postoperative radiation therapy. Data have been analyzed on 94 patients in this preliminary report. The differences between the two groups with respect to local control and survival are not statistically significant at this time. Additional accrual and continued follow-up are necessary in order to make a more definite treatment comparison.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Role of tonsillectomy and adenoidectomy in the management of children with middle ear effusion.

Evidence for the clinical effectiveness of adenoidectomy or tonsillectomy and adenoidectomy in the management of children with persistent middle ear effusions is incomplete and what evidence there is the literature is not convincing. In the first year after tonsillectomy and adenoidectomy there is less otitis media. The beneficial effects of tonsillectomy and adenoidectomy on the incidence of otitis media declines in the second year after the operation. The prevailing opinion is that adenoidectomy is not indicated in the vast majority of children in whom a middle ear effusion has persisted for six weeks or more in spite of antibiotic therapy. Factors favoring an adenoidectomy would be persistent nasal obstruction, persistent purulent rhinorrhea and persistent adenoiditis. The role of tonsillectomy is even less clear, but the decision regarding tonsillectomy is made by most clinicians on the basis of the amount of intercurrent or chronic tonsillitis rather than on the basis of the middle ear effusion per se.

Adenoidectomy↗
PubMedDate not supplied

Bioelectric phenomena in the ototoxicity of nitrogen mustard.

The effects of nitrogen mustard on the electrical potentials of the inner ear were studied, and the results were correlated with the histopathologic findings which have been reported in nitrogen mustard ototoxicity. The endocochlear DC potential (EP) decreased rapidly after an injection of nitrogen mustard (NM). The amplitude of the cochlear microphonics potential (CM) diminished rapidly, and no substantial recoveries were observed. No significant changes in the magnitude of the negative potential of organ of Corti (NPOC) were observed. A large negative summating potential (SP) was recorded even when the amplitude of the CM had diminished.

Acoustic Stimulation↗
PubMedDate not supplied

Pathophysiology of the ototoxicity of cis-diamminedichloroplatinum.

The electrophysiologic and histopathologic changes in the inner ear caused by the administration of cis-diamminedichloroplatinum (CP) were studied in guinea pigs. The endocochlear dc potential (EP) gradually decreased after the intravenous injection of CP and reached approximately 0 mV on the fourth day, but the EP did not become negative. The cochlear microphonics also diminished and could not be recorded on the fourth day. The negative potential of the organ of Corti remained in the normal range during the experiment. A large negative summating potential (SP) was observed one day after injection, but the amplitude of the negative SP became small on the second day. Light microscopic examination demonstrated that the outer hair cells are destroyed in the basal turn of the cochlea and are preserved in the upper turns, while the inner hair cells are almost completely preserved in all turns. The stria vascularis was found to be slightly atrophic. Severe collapse of Reissner's membrane was observed in the basal turn.

Animals↗
PubMedDate not supplied

Ototoxicity of kanamycin sulfate and the barriers in the inner ear.

The effect of kanamycin sulfate administered by three routes on the function of the stria vascularis was monitored electrophysiologically in guinea pigs. The three routes were intramuscular injection, perilymphatic perfusion, or endolymphatic perfusion. Neither systemic administration of 500 mg/kg of body weight per day for 7 to 12 days nor perilymphatic perfusion of 10(-3) M kanamycin affected the endocochlear dc potential (EP). However, with perfusion of kanamycin 10(-3) M in the endolymphatic space, the EP declined severely. Moreover, the decline in the EP was greater with higher concentrations of kanamycin in the endolymphatic perfusate. Furosemide given by each of the three routes produced an approximately equal decrease in the EP. The effects of kanamycin on the cells of the stria vascularis and the evidence for the perilymphatic-endolymphatic and blood-cochlear barriers are discussed.

Animals↗
PubMedDate not supplied

Evoked responses from inferior colliculus as an index of hearing thresholds in guinea pigs.

Bipolar electrodes were implanted in the inferior colliculus of 10 healthy guinea pigs, and visual detection level thresholds of auditory evoked responses were obtained at 17 frequencies between 0.5 and 20.0 kHz. One microvolt isopotential curves from the round window for the same test frequencies were obtained in these animals. A comparison between the evoked response threshold curves and previous reports of the behavioral audiogram reveals a favorable correlation. The cochlear potential curve, however, appears to be a less efficient predictor of the audibility curve than the evoked response thresholds. The utility of evoked response audiometry from the inferior colliculus for quickly assessing auditory thresholds in the guinea pig is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

A method for determining cortical auditory thresholds in guinea pigs.

A method for measuring evoked cortical potentials to acoustic stimuli through the intact dura mater of the guinea pig without computer averaging studied. After exposure of the dura overlying the auditory cortex on the left side, thresholds to acoustic stimuli presented to the right ear were determined with a double tipped silver electrode by visual detection on an oscilloscope. The thresholds obtained are compared with other methods of determining audibility levels in the guinea pig. With relatively simple instrumentation, this method provides rapid and accurate determination of the audibility curve.

Acoustic Stimulation↗
PubMedDate not supplied

Comparison of preoperative and postoperative radiation therapy for patients with carcinoma of the head and neck. Interim report.

Three hundred and fifty-four patients with squamous cell carcinoma of the oral cavity, oropharynx, supraglottic larynx, hypopharynx or maxillary sinus have been randomized for preoperative radiation therapy and surgery versus surgery and postoperative radiation therapy plus, in the case of patients with lesions of the oral cavity and oropharynx, radical radiation therapy. Data have been analyzed on 320 patients in this interim report. In the supraglottic larynx group local-regional control is significantly better for surgery and postoperative radiation therapy. The treatment differences in local-regional control in the oral cavity oropharynx and hypopharynx groups are not statistically significant. No statistically significant treatment differences exist for survival in all sites or in any site; continued follow-up is necessary to make definite treatment comparisons.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Vomeronasal organs and nerves of Jacobson in the human fetus.

The vomeronasal organs and nerves of Jacobson were found on both sides of the nasal septum in a 28-week human fetus. The vomeronasal organ in the human is a tubular structure with an opening into the nasal cavity anteriorly and closed posterior end. The vomeronasal nerve is distributed equally to the medial and lateral aspects of the organ, courses along the nasal septum and goes through the cartilaginous cribriform plate with the olfactory nerve. The cellular configuration of the vomeronasal organ is similar to the olfactory neuroepithelium. No areas of receptor-free epithelium were found in the vomeronasal organs. Intraepithelial blood vessels and mitotic figures were not observed in the epithelium of the vomeronasal organs at 28 weeks. The lack of intraepithelial blood vessels and mitoses may suggest that the vomeronasal organs are undergoing degeneration at 28 weeks of gestation.

Humans↗