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Biomedical subjects

A J Duvall

Publications and source records attributed to A J Duvall.

At least 19 recordsLinked to original sources
PubMed1992

Bacterial tympanogenic labyrinthitis, meningitis, and sensorineural damage.

Pathologic changes (sensorineural hearing loss, labyrinthitis, meningitis) can follow otitis media. Various macromolecular substances demonstrably enter the inner ear via the round window membrane, but its permeability to bacteria is less known. We inoculated Streptococcus pneumoniae type 7F bilaterally into the middle ears of two groups of chinchillas, with and without grafted round window membranes. Inner ears of inoculated animals were observed by light and electron microscopy. None with continuous grafts had labyrinthitis. Bacteria penetrated all three layers of nongrafted round window membranes and into all cochlear turns, entering Schuknecht's channels and following neuronal pathways; nerves were often degenerated, hair cells were damaged or missing, and the stria vascularis was edematous and hemorrhagic. The neural damage suggests a mechanism for the hearing loss that can follow otitis media. Absence of labyrinthitis and meningitis in grafted animals suggests a tympanogenic pathway for the bacteria.

Animals↗
PubMed1992

Spontaneous regression of juvenile nasopharyngeal angiofibroma.

There is debate concerning the natural history of juvenile nasopharyngeal angiofibromas, especially whether or not they can spontaneously regress. Often claimed, spontaneous regression has not been well documented. To our knowledge, this is the first report in which a biopsy-proven juvenile nasopharyngeal angiofibroma spontaneously resolved. A second, less well-documented case is discussed.

Adolescent↗
PubMed1992

Maxillary sinus atelectasis.

Two patients are presented with maxillary bone loss and atelectasis of the sinus walls in association with chronic subclinical maxillary sinusitis. Maxillary sinus atelectasis results in a mild cosmetic deformity, but may also cause diplopia by involving the orbital floor. Ostial obstruction and inflammation-mediated osteopenia are postulated to be the responsible mechanisms. Surgical treatment of the sinusitis may prevent progression of the bone loss.

Adult↗
PubMed1992

Esthesioneuroblastoma presenting as sudden unilateral blindness. Histopathologic confirmation of optic nerve demyelination.

We report here a case of esthesioneuroblastoma an 11-year-old girl presenting as acute loss of vision with minimal evidence of orbital, nasal, or paranasal sinus disease, a rare presenting symptom for this tumor. The initial diagnosis was postviral optic neuritis, a pattern of presentation not previously reported. When vision failed to improve, magnetic resonance imaging revealed a lesion in the posterior ethmoid and sphenoid sinuses. After a biopsy, the tumor was excised through the cranium and paranasal sinuses. A mass completely surrounding the optic nerve without invasion was found. Histochemical staining suggested demyelination secondary to compression, confirming the clinical impression of optic neuritis. Anti-Leu 7 monoclonal antibody is useful in characterizing of this tumor, since other immunochemical stains can be misleading. Radiation and chemotherapy were given after the tumor was removed. Two years later, the patient has had neither recurrence nor complications.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Cochlear permeability of neomycin and gentamicin: an immunohistochemical study.

Aminoglycoside antibiotics (AGAs) target specifically the cochleo-vestibular hair cells, but with varied ototoxicity. Differences in their penetration and clearance rates into the membranous labyrinth may play a role. This in turn may be related to a difference in the number of amine groups, the cationic nature, as well as the molecular weight and size of the AGA molecule. Immunohistochemical labeling techniques were used to study the pathways of gentamicin and neomycin from the perilymph into cochlear tissues and target cells. The more cochleotoxic AGA, neomycin, penetrated into cochlear tissues faster than the less cochleotoxic AGA, gentamicin.

Animals↗
PubMed1991

Transport of 5-hydroxydopamine and horseradish peroxidase through the perilymph-endolymph barrier.

The distribution of 5-hydroxydopamine (5-OHDA) and horseradish peroxidase (HRP) in the cochlea was examined by light and electron microscopy after perilymphatic perfusion. Reaction product of 5-OHDA was observed along the endolymphatic surface of the cochlear duct in both 10-minute and 30-minute perfusions, while that of HRP was observed only in the 30-minute perfusion. Both tracers were found in pinocytotic vesicles of Reissner's membrane, Claudius' cells, and Hensen's cells. No labeling was seen in tight junctions of the epithelial cells lining the scala media. The epithelial cells of the spiral prominence showed various degrees of degeneration in the 5-OHDA experiment. These morphologic findings suggest that 5-OHDA and HRP can enter the endolymphatic space from the perilymphatic space by pinocytosis and that the degree of transport depends on the size of the particles.

Animals↗
PubMed1991

Combined laser phototherapy and growth factor treatment of bronchial obstruction after lung transplantation.

Lung transplantation has resulted in dramatic functional improvement in patients with end-stage pulmonary diseases. Among the complications of lung transplantation are dehiscence and stenosis at the site of the bronchial or tracheal anastomosis. In this case report, we describe a single lung transplant recipient in whom partial bronchial dehiscence, followed by exuberant growth of granulation tissue, resulted in obstruction of the bronchial lumen. After mechanical dilation failed to produce lasting relief of bronchial obstruction, a novel approach to this problem was successfully employed: YAG laser phototherapy was used to remove obstructing granulation tissue, followed by application of a preparation derived from autologous blood platelets to promote epithelialization of the bronchial anastomosis. The bronchus remains patent and fully epithelialized six months after therapy.

Adult↗
PubMed1990

Uptake of horseradish peroxidase by the middle ear mucosa in experimentally induced otitis media.

Electron microscopy was used to study the characteristics of uptake of the protein tracer, horseradish peroxidase (HRP), by the middle ear mucosa of chinchillas. Two types of experimental otitis media were used: serous otitis media (SOM) produced by eustachian tube obstruction and purulent otitis media (POM) produced by inoculation of Streptococcus pneumoniae type 7F. HRP was placed in each tympanic bulla for either 1 min or 10 min. In the 1-min installation of HRP, the degree of HRP uptake was higher in SOM and POM animals than in control animals. Following the 10-min installation of HRP, the degree of HRP uptake was higher in SOM and POM animals than in control animals. Following the 10-min installation of HRP, the degree of tracer uptake was almost the same as among the control, SOM and POM animals. The mechanism of uptake was pinocytosis. In another experiment, 5-hydroxydopamine (mol. wt. 256) was used as a small tracer placed into the bulla to examine the permeability of epithelial tight junctions. No labelling of reaction product was observed in the tight junctions of the control, SOM or POM animals. These findings suggest that otitis media increases the uptake of HRP by pinocytosis and that epithelial tight junctions remain intact in inflammation of the middle ear cavity.

Animals↗
PubMed1990

Morphologic and biochemical study of vascular permeability of the middle ear mucosa in experimental otitis media.

The vascular permeability of the middle ear mucosa of chinchillas was examined by light and electron microscopy using horseradish peroxidase (HRP). Two kinds of experimental otitis media were used: serous otitis media (SOM) produced by eustachian tube obstruction and purulent otitis media (POM) produced by inoculation with Streptococcus pneumoniae type 7F. Normal mucosa showed no leakage of HRP. In SOM, vessels were dilated and tortuous, but they did not show HRP leakage. In POM, vessel leakage of HRP was extensive. Biochemically, we measured the middle ear effusion-to-serum ratio of both albumin and alpha 2-macroglobulin by an immunodiffusion method. The ratios of the two marker proteins for vascular permeability were significantly higher in POM than in SOM. This suggests that POM increases vascular permeability to a higher degree than SOM, and morphologic findings in the middle ear mucosa correlate with the biochemical composition of the middle ear effusion.

Albumins↗
PubMed1988

Resolution of obstructive sleep apnea in Hurler syndrome after bone marrow transplantation.

Hurler syndrome, a lethal inborn error of lysosomal metabolism, results from the systemic accumulation of glycosaminoglycan. The progressive deposition of glycosaminoglycan in tissues of the upper aerodigestive tract has been suspected as the cause of airway obstruction, and many children have required tracheostomy. In a 3-year-old patient with Hurler syndrome, polysomnography confirmed the clinical impression of obstructive sleep apnea. Biopsy of an enlarged tonsil demonstrated that more than half the tissue volume resulted from abnormal lysosomal inclusions in macrophages. Three months after transplantation, repeat testing demonstrated resolution of airway obstruction, and 6 months after transplantation, tonsil biopsy showed complete absence of lysosomal inclusions. Bone marrow transplantation produces effective metabolic correction for Hurler syndrome and may be life-saving for patients with obstructive apnea.

Airway Obstruction↗
PubMed1987

The permeability of the round window membrane during otitis media.

Studies of the permeability of the round window membrane (RWM) during otitis media are important because toxins and cellular components that occur in otitis media as well as pharmacologic agents used in treating the disease have the potential to cross the RWM and pass into the inner ear. Twenty-five cats were evaluated electron microscopically as to the passage of a tracer, horseradish peroxidase, through normal RWMs and RWMs three days, one week, and two weeks following eustachian tube obstruction. Passage at three days following obstruction was similar to passage through the normal RWM. Following one to two weeks of obstruction, the permeability of the membrane was drastically reduced. The reduction in permeability was probably due to the presence of residual effusion overlying the membrane, the presence of granulation tissue within the niche, and a thickening of the RWM.

Animals↗
PubMed1987

Frontal sinus fractures. Analysis of treatment results.

A retrospective study of 112 consecutive patients with frontal sinus fractures who were available for follow-up is presented. Significant complications are possible, especially with fracture of the posterior sinus wall. When indicated, the sinus is reconstructed with wire using free denuded fragments if available. Severe complications in displaced posterior wall fractures were less common when treatment was by sinus obliteration than by cranialization. Computed tomography has improved the evaluation, especially when a posterior wall fracture is suspected.

Anti-Bacterial Agents↗
PubMed1987

Local vs systemic effects of acoustic trauma on cochlear structure and transport.

Whether certain effects of acoustic trauma on cochlear structure and function were due to local or systemic agents was investigated in the chinchilla. After unilateral ossicular disarticulation, the animals were given a noise exposure known to cause cochlear damage and vessel transport changes in the stria vascularis. The cochleas with disarticulated ossicular chains received an effective exposure well below one that causes pathologic damage. Only the cochleas with intact ossicular chains showed an increase in the permeability of the strial vessels to horseradish peroxidase tracer and manifested strial edema and organ of Corti damage. These results indicate that the effects of acoustic trauma on cochlear structure and strial vessel transport are induced locally, not systemically. In addition, the minimum time of exposure to 120-dB, 700- to 2800-Hz noise that causes massive cochlear damage in the chinchilla was shown to be between five and ten minutes.

Animals↗
PubMed1987

Juvenile nasopharyngeal angiofibroma: diagnosis and treatment.

Juvenile nasopharyngeal angiofibroma (JNA) is an uncommon, histologically benign vascular tumor that occurs almost exclusively in adolescent males. While occasional mention is made of the occurrence of JNA in females and in older males, only four cases have withstood rigorous clinicopathological review. This neoplasm accounts for less than 0.05% of all benign lesions that originate in the nasopharynx. Its clinically malignant behavior is a result of its propensity for locally destructive growth and fatal hemorrhage. The evolution in the management of these tumors has been the subject of much interest and much confusion. The advents of computed tomographic (CT) scanning, selective angiography with embolization, and refinements in surgical approaches have revolutionized operative management of these lesions by allowing more realistic selection of surgical candidates, better preoperative planning, and more flexible (yet aggressive) primary surgical treatment. The attendant reduction in morbidity and mortality of contemporary surgical management of this disease has largely obviated the argument of those who advocate use of radiotherapy as the primary treatment modality for this benign lesion. This latter view is based on the reports of massive hemorrhage, significant incidence of incomplete removal, and mortality reported in the older surgical literature. This article details our experience with a series of 31 patients who had clinicopathological diagnoses of JNA and were treated between 1954 and 1984. It furthermore represents an update of our previously reported series.

Adolescent↗
PubMed1986

Long-term results with nasofrontal duct reconstruction.

The findings and results of 50 consecutive nasofrontal duct reconstructions are analyzed and presented. Postoperative recurrence of frontal sinus disease occurred in 14% of the cases and there were no significant postoperative or intraoperative complications. There was no instance of failure in patients with a history of trauma to the nasofrontal duct and only two recurrences in patients with mucocele or pyocele. Nasofrontal duct reconstruction offers more direct access to the ethmoid cell system than osteoplastic flap obliteration. In addition, it is a lesser procedure with fewer complications. The physiologic function of the sinus is restored without the risk of burying disease. Nasofrontal duct reconstruction is an effective option for the treatment of chronic frontal sinus disease if the sinus mucosa is not irreversibly damaged.

Adult↗
PubMed1984

The human round window membrane. An electron microscopic study.

The normal adult human round window membrane was examined by transmission electron microscopy. The membrane consists of the following three layers: (1) an outer squamous epithelial layer with an underlying basement membrane; (2) a middle fibrous layer containing collagen, elastin, fibrocytes, vessels, and nerves; and (3) an inner layer of mesothelial cells. Mucosal membrane veils that cover the round window membrane, forming "false" round window membranes, are also described. These membranes are also three layered, including (1) an outer epithelial layer with an underlying basement membrane, (2) a middle fibrous layer containing collagen, elastin, fibrocytes, vessels, and nerves, and (3) an inner epithelial layer with an underlying basement membrane. Ultrastructural differences between these two structures are discussed.

Aged↗