摘要:

HypothesisChemical sympathectomy with 6-hydroxydopamine (HDA) increases middle ear bulla bone resorption in the Mongolian gerbil.BackgroundMany diseases of the middle ear have pathologic processes linked to abnormal bone remodeling. Numerous factors controlling bone remodeling have been identified. An understanding of these factors and their role in pathologic remodeling is therefore essential. Sympathectomy, induced both surgically and pharmaceutically, is known to increase middle ear bone resorption, suggesting a role for the central nervous system in bone metabolism. This effect, however, may be confounded by hemodynamic changes induced by hemicranial surgical sympathectomy or by uncertainty in the action of pharmaceutical agents on the sympathetic nervous system. In this experiment, a third modality with unique properties, chemical sympathectomy with HDA, was used to quantify further the effect of sympathectomy on middle ear bone remodeling.MethodsEight gerbils designatedexperimentalreceived intraperitoneal injections of HDA (75 mg/kg) for 1 week, whereas eight animals designatedcontrolreceived similar injections of saline. One week after injections, the animals were euthanized and bulla bone samples were analyzed histomorphometrically to determine osteoclastic activity. In addition, to assess for any direct effects on bone metabolism, the activity of HDA was determined in vitro using the calvarial calcium release assay.ResultsThe in vitro study found HDA to have no direct stimulatory activity on calcium release. The in vivo study showed HDA to increase osteoclastic activity significantly in middle ear bone.ConclusionHDA-induced sympathectomy increases bone resorption in gerbilline middle ear bone.

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

HypothesisNatural stimulation of the vestibular end organs will produce alterations in the local vestibular microvascular blood flow.BackgroundThe vestibular and cardiovascular systems require a coordinated interaction to maintain organ perfusion during rapid positional and postural changes. However, the detailed relationship of these systems is not well understood. There have been no previous descriptions of local vestibular blood flow (VBF) during natural stimulation (NS) conditions.MethodsIn vivo VBF and systemic blood pressure (BP) in the Mongolian gerbil during natural stimulation. Using laser Doppler flowmetry, the authors obtained continuous measures of local VBF in both anesthetized and alert gerbils during sinusoidal rotational stimuli. Simultaneous recordings of systemic BP were collected from the contralateral common carotid artery.ResultsThe anesthetized gerbils showed stable VBF and BP during all vestibular stimuli. By contrast, alert subjects demonstrated a significant response to natural stimulation. The VBF increased 28% over baseline, and systemic BP increased 8% during a 45-second, 0.133-Hz sinusoid. Decreases in BP of 8% and 5%, respectively, were seen with a 0.10 and 0.20 Hz, 360-second stimulus. A corresponding determination of VBF during the extended stimulus conditions was not technically possible.ConclusionsTo the authors' knowledge, these are the first in vivo descriptions of vestibular blood flow during natural stimulation. In the alert animals, VBF increased in response to NS. This increase in flow does not appear to be directly dependent on systemic blood pressure changes and indicates that the vestibular microvasculature is closely regulated.

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectiveTo review current knowledge of the pathophysiology of otosclerosis and to review hypotheses for the amelioration of this disease.Data SourcesReview of the literature and experimental observations by the authors.ConclusionsOtosclerosis is a localized disease of bone remodeling within the otic capsule of the human temporal bone. Unlike other similar bone diseases, it does not occur outside of the temporal bone. These lesions seem to begin by resorption of stable otic capsule bone in adults, followed by a reparative phase with bone deposition. There are clearly genetic factors that lead to this disease, but measles virus infection and autoimmunity also may play contributing roles. Surgical correction of the conductive hearing loss is highly effective, but nonsurgical intervention has not yet been shown to prevent or slow the disease. Of the factors that may inhibit this process, fluorides, cytokine inhibitors, and bisphosphonates, third-generation bisphosphonates appear to hold the most promise.

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The anatomy of the cochlea, one of the most complicated parts of the inner ear, is associated with numerous eponyms, mostly originating from German anatomists of the 19th century. In addition to the organ of Corti and Reissner's membrane, which are the best known, nine other eponymic anatomic terms are associated with the cochlea: Deiters' cells, Hensen's cells, Hensen's strip, Claudius' cells, Boettscher's cells, Rosenthal's canal, Hardesty's membrane, Huschke's teeth, and Nuel's space. All of these anatomic eponyms are described, with their original references.

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1531-7129    

出版商:OVID    

年代:2001

数据来源: OVID