Search PubMed⌕ Search

Biomedical subjects

R A Chole

Publications and source records attributed to R A Chole.

At least 91 records · Page 5Linked to original sources
PubMed1983

Disparity in the cytocochleogram and the electrocochleogram in aging LP/J and A/J inbred mice.

The auditory systems of aging LP/J and A/J inbred mice were studied using electrocochleography (AP thresholds) and surface preparation cytocochleography. Both strains showed marked age-related auditory threshold elevation, the LP/J demonstrating more pronounced elevation with age than the A/J. Surprisingly, the cytocochleograms showed the opposite relationship: the A/J strain had more loss of hair cells than the LP/J. The elevation of AP thresholds of the LP/J mouse was far out of proportion to the expected auditory deficit on the basis of the cytocochleogram alone. Auditory deficits in the aging LP/J mouse must be due to factors other than anatomical loss of sensory cells.

Aging↗
PubMed1982

Ossicular replacement with self-stabilizing presculptured homologous cartilage.

The use of self-stabilizing, alloplastic ossicular replacement prostheses introduced by Shea and Homsy has improved postsurgical hearing results in patients with major ossicular defects. While hearing results after total and partial ossicular replacement are good, many authors have reported high rates of extrusion of these alloplastic materials. A technique is herein described in which an all-cartilage homograft is presculptured into a self-stabilizing configuration. Twenty-three such total and partial ossicular replacement grafts were performed with a follow-up of at least 25 months; none of the cartilage struts has extruded. The self-stabilizing, presculptured homologous cartilage graft provides an alternative for surgeons who wish to avoid alloplastic materials in ossicular reconstruction.

Cartilage↗
PubMed1981

Increased ototoxicity in both young and old mice.

Preweanling, postadolescent, and post-middle-aged CBA/J mice received injections of kanamycin sulfate for two weeks, followed by electrocochleographic (isoelectric auditory nerve-evoked potential thresholds from 2,000 to 64,000 Hz) and histocochleographic (hair cell counts from cochlea whole-mount preparations) analysis. The preweanling mice had structural and functional losses from all portions of the cochlea, while the postadolescent mice had no structural and minimal functional loss. The oldest mice had basal inner and outer hair cell loss and elevated high frequency thresholds. This is an experimental validation of the clinical observation that infants are most susceptible to aminoglycosidic ototoxicity. It also support the suspicion that older persons are also susceptible to ototoxicity and provides the first animal model for experimentally investigating these age-dependent effects.

Aging↗
PubMed1981

Preparation of small temporal bones for high-resolution light microscopy.

A technique was used for rapid processing of small temporal bones for high-resolution light microscopy, Temporal bones were decalcified in edetic acid and embedded in glycol methacrylate. Sections (thickness, 1 micrometer) were stained with a variety of stains that demonstrated cellular details not usually seen with conventional methods. This technique is suitable for routine histologic, histochemical, and radioautographic studies of small temporal bones.

Animals↗
PubMed1981

Effects of neonatal thyroxine, genotype, and noise on the ear and audiogenic seizures.

Seyfried, Glasser, and Yu recently reported that the DBA/2J mouse genotype, which is innately susceptible to audiogenic seizures, has high neonatal levels of thyroxine (T4) and that neonatal injections of T4 induce susceptibility in the C57BL/6J mouse. In the C57BL/6J mouse, neonatal T4 injections produced a temporary peripheral auditory dysfunction which appeared to be conductive in nature. A cochlear dysfunction was also seen in the DBA/2J mouse and in the acoustically primed C57BL/6J mouse. Since a peripheral auditory threshold elevation in these latter groups of mice appears to be causally related to their susceptibility to audiogenic seizures, it is likely that at least a portion of the susceptibility that Seyfried et al. reported was due to the effects of T4 on the ear.

Acoustic Stimulation↗
PubMed1981

Cholesteatoma: spontaneous occurrence in the Mongolian gerbil Meriones unguiculatis.

Spontaneous aural cholesteatomas were found in thirty-two of seventy ears (45.7 percent) of adult Mongolian gerbils, Meriones unguiculatis. These cholesteatomas arise from the tympanic membrane and the medial ear canal. The advancing front of these cholesteatomas is histologically identical to that of human cholesteatomas. Since the gerbilline cholesteatoma erodes bone and invades the labyrinth and the cranial cavity, it provides an animal model with which to study the destructive properties of human cholesteatoma.

Animals↗
PubMed1980

Photography of the tympanic membrane. A new method.

A 2.7-mm Karl Storz-Hopkins telescope was adapted to a single-lens reflex camera and photographs of the tympanic membrane obtained with electronic flash illumination. This system provides a view beyond the narrow isthmus of the external auditory canal and end-point lighting. Resultant photographs demonstrate the entire tympanic membrane, including the anterior sulcus; the depth of field is infinite and the image size is large.

Ear Diseases↗
PubMed1980

Autoradiographic localization of vitamin A in the stria vascularis of the rat cochlea.

Vitamin A is present in the membranous cochlea at a higher concentration than in most other mammalian tissues. In order to localize this substance in the cochlea, 11(3)[H] retinyl acetate was administered to vitamin A-deficient rats. An autoradiographic study of these cochleas revealed labelling of the stria vascularis; the sensory cells and ganglion cells were not labelled.

Animals↗
PubMed1980

Age-related auditory loss in the Mongolian gerbil.

Mongolian gerbils were examined for auditory nerve function at five ages, ranging from 90 to 730 days postpartum. Electrocochleograms were obtained in response to tone pips at frequencies ranging from 1 to 64 kHz. An age-related threshold increase was noted at all frequencies. The pattern of auditory loss is different from that observed in the aged rat, guinea pig, and mouse.

Aging↗
PubMed1980

Anatomical studies of the posterior petrous apex with regard to hearing preservation in acoustic neuroma removal.

Some surgeons have shown that tumors of the internal auditory canal and cerebellopontine angle may be removed with preservation of hearing through the suboccipital approach. If hearing is to be conserved, the cochlear division of the VIIIth cranial nerve and blood supply of the labyrinth must be preserved. In addition, surgical entry into the labyrinth, upon removal of the posterior wall of the internal auditory canal, must be avoided since it is likely to result in permanent sensorineural hearing loss. Careful anatomic dissection of 20 human temporal bones has shown that exposure of the lateral-most recess of the internal auditory canal from a suboccipital approach is impossible without injury to the endolymphatic duct, common crus, vestibule or ampulla of the posterior semicircular canal. Previous authors have suggested that exposure of the horizontal crest may be used as a safe landmark in avoiding labyrinthine injury. However, our study has shown that exposure of the horizontal crest usually leads to labyrinthine injury. In 19 out of 20 cases, the labyrinth would have been entered had the horizontal crest been used as a landmark for the lateral limit of bone removal. The application of the anatomical relationship quantified in this study may improve our ability to avoid labyrinthine injury in the suboccipital removal of acoustic neuromas.

Ear Canal↗
PubMed1980

Genotypic differences in behavioral, physiological and anatomical expressions of age-related hearing loss in the laboratory mouse.

The auditory nerve isoelectric thresholds, in response to tone pigs ranging from 5 to 20 kHz, are similar in the young C57BL/6 and CBA/J mice, although the latter genotype has somewhat more sensitive responses from 30 to 80 kHz. But their behavioral audiograms, obtained by the classical conditioning technique of Ehret, are very discrepant. Even though the behavioral audiogram of the CBA/J mouse can be predicted by measurements from its auditory nerve, the behavioral thresholds of the young C57BL/6 mouse are approximately 40 dB less sensitive than its electrophysiological measurements. Cochlear hair cell loss was not evident in young mice of either genotype. As the CBA/J approaches the end of its predicted life span, its auditory anatomy, physiology and behavior are not significantly altered; but those rare individuals, who exceed their predicted life span by 40% finally develop hearing loss of a mixed nature. By contrast, the C57BL/6 mouse shows a relatively rapid decline of hearing as it ages. By 200 days of age, its auditory nerve responses are 30 dB less sensitive at 5 kHz, and 55 dB less sensitive at 30 kHz, than similar measures taken at adolescence. Over this same age span, its behavioral sensitivity has only declined by 15 and 25 dB at these two frequencies. Hair cell counts correlated poorly with both behavioral and electrophysiological auditory measures in the C57BL/6 mouse.

Age Factors↗
PubMed1976

Temporal bone histopathology in experimental hypovitaminosis A.

Twenty-five years ago hearing loss was observed in some subjects during a comprehensive study of the effects of hypovitaminosis A on human volunteers. Experimental studies documenting histopathological changes in the temporal bone due to hypovitaminosis A are conflicting. Even the recent textbooks of otolaryngology and physiology make no mention of a role of vitamin A in the ear. To explore the role of vitamin A in the ear adult and weanling rats maintained on a diet totally lacking vitamin A were sacrificed at intervals. Their temporal bones were examined with the light microscope. After six weeks on a vitamin A free diet weanling rats showed hypertrophy of the periostial portions of the otic capsule. At 16 weeks a narrowing of the internal auditory canal due to bony exostoses was present. The neuroepithelia of the cochlea and the vestibular apparatus were histologically normal even in the longest surfiving animals. Adult rats maintained on a vitamin A free diet showed minimal thickening of the bone adjacent to the internal auditory meatus. The cochlea and the vestibular appartus in these animals remained normal throughout the 28-week experiment. Although we have demonstrated marked abnormalities of the otic capsule in hypovitaminosis A, our results do not support those of some earlier investigators who reported that atrophy of the cochlear and vestibular neuroepithelium occurred in the absence of dietary vitamin A.

Age Factors↗
PubMed1975

Deafness and renal failure due to potassium bromate poisoning.

Several substances are known to have a profound effect on both the kidney and the inner ear. The aminoglycoside antibiotics are toxic to both of these organs. Ethacrinic acid and furosemide affect transport mechanisms in the loop of Henle as well as the inner ear. In addition, studies have suggested antigenic similarities between the stria vascularis of the cochlea and the renal tubules. This report of potassium bromate poisoning and its resultant deafness and renal failure further emphasizes the curious relationship between these two organ systems.

Acute Kidney Injury↗