ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

In an earlier study, epidermal growth factor (EGF) was shown to be effective in healing chronic tympanic membrane (TM) perforations in the chinchilla. The original protocol required rimming of the perforation's epithelial edge, application of a paper patch, placement of a Gelfoam pledget, and then administration of EGF solution. To develop a simple outpatient method of healing chronic TM perforations, an attempt was made to simplify the treatment protocol while preserving efficacy. In the modified experimental protocol, a large Gelfoam pledget was placed over the chronic perforation in contact with the residual TM, without mechanical disruption of the perforation edge or use of a paper patch. Then EGF in phosphate buffered saline (PBS) was applied to the Gelfoam pledget (50 uL of 0.5 mg EGF/mL PBS). A series of control ears received Gelfoam pledgets and PBS. Complete closure of the TM perforation was achieved in 80 percent (12/15) of treated ears but in only 20 percent (3/15) of controls (p<0.01), results similar to those obtained with the original protocol. At long-term follow-up, 4 to 9 months after treatment, EGF-healed TMs were histologically similar to normal TMs, both in their overall thickness and in the relative proportions of the three component layers. In contrast, the few spontaneously healed TMs from the control group were less than half the thickness of normal TMs. To ascertain the optimal EGF concentration for therapeutic effect, a dose ranging study was undertaken. Concentrations at 50 percent and 25 percent of the original proved equally effective in inducing chronic TM perforations to heal. Finally, an ototoxic screening study revealed no significant cochleotoxic effects following topical application of EGF to the middle ear. Based upon these promising results in the animal model, clinical trials of EGF in the management of chronic TM perforations are being initiated.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Although tinnitus affects approximately 9 million people in the United States, a cure remains elusive and the mechanisms of its origin are speculative. The crucial obstacle in tinnitus research has been the lack of an animal model. Over the last decade we have been creating such a model by combining a variety of methodologies, including a behavioral component, to allow for the detection of tinnitus perception. Initially, 2-deoxyglucose had been used to map changes in the metabolic activity after unilateral destruction of the cochlea. It has been found that the initial decrease of the metabolic rate in the auditory nuclei recovered to preoperative values, which could be attributable to the development of tinnitus. The spontaneous activity of single units recorded from the inferior colliculus before and after salicylate administration revealed an increase of discharges, which might reflect the presence of salicylate-induced tinnitus. Recent data have confirmed, and further elaborated this observation, including the discovery of abnormal, epileptic-like, neuronal activity. Finally, the authors have developed a behavioral model of tinnitus, tested it extensively, and used it to measure tinnitus pitch and loudness. The model is presently used for investigating the hypotheses for the mechanisms of tinnitus.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The recent discovery of hair cell regeneration in the avian inner ear raises the possibility that hair cell regeneration might occur in the mammalian cochlea as well. The authors used 3H-thymidine labeling to detect mitotic activity in the cochleas of normal 3-week old gerbils exposed to acoustic trauma. Following an acoustic insult that caused progressively more severe damage in an apical to basal progression,3H-thymidine was injected for 5 days. Control animals were not exposed to the acoustic insult. The gerbils' cochleas were sectioned and processed for autoradiography. In the control cochleas, there were extremely rare labeled cells in the stria, the spiral ligament, and the glial cells around the acoustic nerve fibers. In the damaged cochleas, no evidence of hair cell regeneration or of any cell division within the normal sensory epithelial structures was seen. Three labeled cells were seen in intercellular spaces within the sensory epithelium; they appeared to be macrophages. Frequent cell division was seen in numerous other regions of the damaged cochleas and among glial cells adjacent to the acoustic nerve fibers. It is concluded that there is no evidence for hair cell regeneration following acoustic trauma in the gerbil, but acoustic trauma does induce cell division in numerous other areas of the cochlea.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The etiology of Meniere's disease (MD) remains obscure. Previous studies have shown a highly significant association between sporadic MD and one of the human leukocyte antigen, HLA-C genotypes, whereas disease activity has been related to the detection of enterovirus-specific viral protein (VP1) in the peripheral circulation. This present research extends the HLA association of sporadic cases to the study of families with more than one living member with unequivocal MD. Since the sporadic HLA associations point to chromosome 6 being a candidate region of a possible MD mutation, this area of the human genome has been investigated first; DNA suitable for study by other markers has been stored. The presence or absence of VP1 in the familial MD patients has been measured and related to disease activity at the time of sample collection. The association, in both sporadic and familial cases, of MD and partial HLA class I haplotypes points to a likely MD locus lying between the HLA-C and HLA-A loci on the short arm of chromosome 6. The significant relation between disease activity and circulating VP1 has been confirmed. It is likely that the predisposition to familial MD is attributable to a mutation on chromosome 6, which has been designated M1.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Speech perception skills were measured in five children who had received a 3M/House single-channel cochlear implant and were subsequently upgraded to a multichannel cochlear implant (Nucleus). A rationale was developed based upon performance with the single-channel device and anticipated performance with the multichannel device. All subjects demonstrated improved acoustic thresholds with the multichannel device. Three of the children demonstrated improvements on identification tasks and two on word recognition tasks.

ISSN:0192-9763    

出版商:OVID    

年代:1994

数据来源: OVID