Biomedical subjects

T H Yoon

Publications and source records attributed to T H Yoon.

28 records · Page 2Linked to original sources

PubMed1990

Histopathology of sudden hearing loss.

Eleven temporal bones from eight patients who had clinical histories of sudden hearing loss (SHL) were studied to assess the possible etiopathogenesis. The origin of SHL in seven ears from five patients was obscure, but appeared to be due to multiple causes. Common histopathologic changes in the cochlea, although complex, included atrophy of the organ of Corti and loss of cochlear neurons. Loss of cochlear neurons was the main finding in ears of viral infection. Labyrinthine fibrosis and formation of new bone were seen in two ears associated with vascular insult and in two ears of autoimmune disease. Different histopathologic findings causing SHL were observed even in cases with the same etiology. A case of SHL showing endolymphatic hydrops as the main histopathologic finding is described.

Adolescent↗

PubMed1990

The release of hepatic triglyceride lipase from rat monolayered hepatocytes in primary culture.

The release of hepatic triglyceride lipase from cultured rat hepatocytes and its hormonal regulation were studied. The activity of lipase released into the medium in the presence of heparin was increasing for 24 hours on the 2nd day of culture. The activity in the absence of heparin was only 10% of that in the presence of heparin. When hepatocytes were cultured with anti-hepatic triglyceride lipase IgG, the lipase activity was suppressed by 92%. The results suggest that the enzyme released into the culture medium is identical to hepatic triglyceride lipase which can be released only in the presence of heparin, the mode of release being similar to that of lipoprotein lipase from adipocytes. The addition of colchicine and monensin to the medium resulted in the inhibition of lipase secretion by 20% and 61%, respectively. Insulin enhanced lipase activity only 20%, whereas dexamethasone suppressed the activity by 44%. These data indicated that hepatic triglyceride lipase is secreted and released from hepatocytes in the presence of heparin and its secretion is regulated by hormones.

Animals↗

PubMed1989

Cerebellopontine angle epidermoid cysts: a report on 30 cases.

Thirty cases of cerebellopontine angle epidermoid cysts treated over a period of 20 years are reviewed with regard to their clinical features, the pathophysiology of their symptoms and their management. The predominating symptoms were related to the 7th and 8th cranial nerves and headaches. The signs and symptoms were present for an average period of 4 months. It was not always possible to determine if the signs and symptoms were due to local involvement by the epidermoid, increased intracranial pressure, or both. Diagnostic procedures evolved from angiography and ventriculography to non-invasive computed tomography and MRI. The posterior cranial fossa approach was used in 27 cases. Total excision of the epidermoid was the aim and was carried out in five (18%) patients but concern regarding the preservation of nearby important neurovascular structures forced partial removal in 22 patients. To minimise reformation, the residual epidermoid was carefully coagulated with the aid of the operating microscope and bipolar cautery without damaging surrounding neurovascular structures.

Adolescent↗

PubMed1989

Otologic histopathology of Fabry's disease.

Fabry's disease is a rare progressive X-linked recessive disorder of glycosphingolipid metabolism. The accumulation of glycosphingolipids occurs in virtually all areas of the body, including the endothelial, perithelial, and smooth-muscle cells of blood vessels, the ganglion cells of the autonomic nervous system, and the glomeruli and tubules of the kidney. Although otologic symptoms have been described in these patients, to our knowledge there have been no temporal bone histopathologic reports. We describe the clinical histories, audiometric results, and temporal bone findings of two patients with this rare disorder. Both patients demonstrated a bilateral sloping sensorineural hearing loss audiometrically. Middle ear findings of seropurulent effusions and hyperplastic mucosa were seen in all four temporal bones. Strial and spiral ligament atrophy in all turns, and hair cell loss mainly in the basal turns, were also common findings. The number of spiral ganglion cells was reduced in all temporal bones; however, evidence of glycosphingolipid accumulation was not observed in the spiral ganglia.

Audiometry↗

PubMed1989

Systemic vasculitis: a temporal bone histopathologic study.

Systemic vasculitis includes a broad spectrum of disorders that may involve blood vessels of any size in any organ system. Systemic vasculitis is associated with immunopathogenic mechanisms. Sixteen temporal bones from eight persons were studied to determine histopathologic changes that occur in systemic vasculitis. Three persons had Wegener's granulomatosis, two had polyarteritis nodosa, and three had systemic lupus erythematosus. Otitis media was seen in 15 ears, with ten ears showing chronic middle ear changes and two showing fibrotic inner ear changes. In Wegener's granulomatosis, granulation tissue was observed around the eustachian tube and protympanum, and in polyarteritis nodosa, inflammatory cell infiltrate and thickened blood vessels were observed around the facial nerve. Although sensorineural hearing loss has been described clinically in systemic lupus erythematosus, the present report describes findings in temporal bones, including severe fibrosis and new bone formation throughout the inner ear.

Adolescent↗

PubMed1989

Survey of interactions between middle ear and inner ear.

Diseases with interaction between the middle ear and inner ear include 1) congenital anomalies, 2) trauma, 3) infection/inflammation, 4) tumors, 5) granulomas, 6) ototoxic eardrops, 7) cochlear implants, 8) otosclerosis, 9) Meniere's disease-decompensated, and Meniere's disease with perilymphatic fistula, and 10) perilymphatic hypertension. Clinical and pathological characteristics are briefly categorized in this survey. The clinical utility of exploratory tympanotomy in diagnosis and treatment of middle ear pathology and middle ear/inner ear interactions is commented upon.

Ear↗

PubMed1989

Congenital cholesteatomas of the cerebellopontine angle.

Thirty cases of congenital cholesteatomas of the cerebellopontine angle (CPA) treated over a period of 20 years are reviewed with regard to their clinical features, the pathophysiology of their symptoms, and their management. The predominant symptoms were related to cranial nerves VII and VIII and headaches. Signs and symptoms were divided into those caused by local involvement of the cholesteatoma, increased intracranial pressure, or both. Diagnostic procedures from invasive procedures such as ventriculography to more sophisticated noninvasive procedures including computed tomography and magnetic resonance imaging are discussed. The surgical management of 27 congenital cholesteatomas was accomplished via a posterior cranial fossa approach. Total excision of the cholesteatoma was the aim but was carried out in only five (18%) patients because of concern regarding the preservation of nearby neurovascular structures. Partial excision was possible in 22 (82%) patients. To minimize re-formation, the residual cholesteatoma was carefully cauterized with the aid of the operating microscope and bipolar diathermy without damaging surrounding neurovascular structures. Follow-up has ranged from 2 to 15 years, with four (13%) cases of re-formation.

Adolescent↗

PubMed1988

Enhanced synthesis and secretion of apolipoprotein E from sciatic nerves of streptozotocin-induced diabetic rats after injury.

To elucidate the pathogenesis of diabetic neuropathy, synthesis and secretion of apolipoprotein E (apo E) from sciatic nerves after injury was studied in normal and streptozotocin-induced diabetic rats. Seven, 14, 28, 45 and 59 days after making crush injury on sciatic nerves with concomitant administration of streptozotocin (50 mg/kg body weight), the nerves were taken out and incubated with [35S]methionine. The [35S]labeled apo E was precipitated with specific antiserum. The amounts of apo E secreted into medium by nerves of diabetic rats were 7 times greater than those of non-diabetic rats 7 days after injury. This enhanced secretion of apo E was relatively selective for this protein, since the ratio of the immunoprecipitable apo E to the TCA preciptitable protein in the medium increased in diabetic rats. Intriguing possibility deduced from these results is that the secretion of apo E is involved in the development of diabetic neuropathy.

Animals↗

PubMedDate not supplied

Pathology and pathogenesis of tympanic membrane retraction.

Temporal bones without evidence of otitis media, as well as temporal bones with various types of otitis media, were examined for the presence of retractions of the tympanic membrane and their related histopathologic progression to the formation of cholesteatoma. Retractions were not present in non-otitis media, purulent, or mucoid otitis media. Retractions were observed in 2.1% of temporal bones with serous otitis media and 19.5% of temporal bones with chronic otitis media. All temporal bones with retractions demonstrated evidence of current or previous otitis media. Histopathologic changes of the middle ear cleft were associated with the type and degree of retraction. This study supports the continuum theory according to which otitis media with effusion eventually leads to a variety of sequelae and/or to chronic otitis media. The tympanic membrane appears to follow progressive changes, from simple retraction to retraction pockets and finally to cholesteatoma.

Cholesteatoma↗

PubMedDate not supplied

Salivary gland choristoma of the middle ear: a case report.

A choristoma is a nonneoplastic proliferation of histologically normal tissue that forms at an abnormal site. It is extremely uncommon in the middle ear space. It appears to be a developmental abnormality and may be associated with abnormalities of adjacent structures. It usually occurs with unilateral conductive hearing loss and requires a differential diagnosis from other mass lesions in the middle ear cavity. This article discusses a case of salivary gland choristoma of the middle ear that we believe to be the 24th case reported on this subject.

Audiometry↗