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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

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↗
PubMed1979

Usher's syndrome type III.

We describe a rare example of Usher's syndrome type III in a 9-year-old boy. This type is characterized by retinitis pigmentosa and progressive sensorineural deafness.

Audiometry↗
PubMed1979

The "chronic" ear: how to manage mild to severe otitis.

Otitis media initially involves only the mucosa, but if unchecked, may eventually spread to bone, causing bony erosion and severe osteitis that can have life-threatening CNS complications. Placement of a PE tube generally is all that is necessary to eliminate middle ear fluid and restore normal hearing in serous otitis media and adhesive otitis media. Mastoidectomy is required in more advanced chronic ear disease; if disease is not too extensive, hearing may be restored by tympanoplasty.

Cholesteatoma↗
PubMed1979

Morphological alteration of the stria vascularis after administration of the diuretic bumetanide.

Chinchillas were given either a single injection of the diuretic bumetanide (18 mg/kg body weight) or saline-sodium hydroxide and sacrificed at 10 min, 1 hr and 24 hr after the injection. Slight stria edema was present at 10 min, marked edema at 1 hr and no edema 24 h after bumetanide. The edema began in the first cochlear turn at 10 min and spread to the second turn by 1 hr. Along with edema, marginal cell bulging, potential capillary constriction and the formation of marginal cell membranous structures occurred after bumetanide treatment.

Animals↗
PubMed1978

Mucoceles with intracranial and extracranial extensions. Report of two cases.

Two cases of unusual childhood mucocele are presented. These serve to illustrate the great potential these lesions have for slow, insidious development and insinuation of themselves into regions of the head and face where they are difficult to remove surgically. A description of the staged surgical excision is presented to emphasize the importance of radical removal of these benign lesions.

Adolescent↗
PubMed1977

Transnasal transsphenoidal approach to the sella.

The transnasal transsphenoidal approach to the sella turcica has been refined and perfected through advances in medicine and technology. Originally performed for excision of pituitary adenomas, its present primary use is pituitary ablation is hormonally dependent diseases. Our study of 55 patients who have undergone this procedure during the years 1970-1975 demonstrates that this microscopic technique gives excellent exposure and visualization of intrasellar contents. Our method gives excellent exposure and visualization of intrasellar contents. Our method with several instrument modifications is discussed. It is technically an easy procedure with a minimum of morbidigy and mortality.

Adenoma↗
PubMed1977

An endoscopically-introducible T-tube for tracheal stenosis.

Five cases of tracheal stenosis are presented, and aspects of etiology and pathophysiology of the disease are discussed. A new soft, flexible T-tube is described along with a method of endoscopic introduction. Although many patients with tracheal stenosis will eventually need tracheal reconstruction, stenting may be definitive in selected cases.

Adult↗