Biomedical subjects

R A Chole

Publications and source records attributed to R A Chole.

At least 73 records · Page 4Linked to original sources

PubMed1987

Use of presculpted, banked cartilage transplants in ossicular reconstruction.

Ossicular reconstruction was performed in 102 ears using homologous, costochondral cartilage. The cartilage was presculpted into a total ossicular replacement or partial ossicular replacement configuration by a tissue bank and stored for later use. The performed transplants were further shaped in the operating room to suit the anatomical findings during tympanoplasty. The postoperative hearing results as determined by the airbone gap were comparable with those obtained with alloplastic materials (mean gap, 18.6 dB). No extrusions occurred; an analysis of hearing after three years showed that 96.7% of the initial hearing improvement was maintained in 51 ears available for study. Homologous cartilage in the total ossicular replacement or partial ossicular replacement configuration is as effective as alloplastic materials in ossicular reconstruction and it does not resorb or extrude with time.

Audiometry↗

PubMed1987

Pressures exerted by experimental cholesteatomas.

Previous studies have shown that transmitted pressure may be an important factor in the induction of osteoclastic bone resorption by cholesteatoma. However, the ability of cholesteatomas to actually exert pressure on adjacent structures has not been studied. Implantable pressure gauges were used to measure static pressure exerted by induced gerbilline cholesteatomas. Cholesteatomas were found to exert pressures between 1.31 mm Hg and 11.88 mm Hg. Osteoclastic bone resorption was observed in areas where the pressure gauge transmitted these pressures to bone. Thus, pressure exerted by an expanding cholesteatoma may be an important factor in the induction of osteoclastic bone resorption.

Animals↗

PubMed1987

Mongolian gerbil tympanic membrane. Normal and with induced otitis media.

Otoscopic observation of the tympanic membrane is the most effective noninvasive means of diagnosing and following the course of experimental otitis media in animal models of the disease in both short-term and in longitudinal studies. Because of the difficulty of viewing the entire tympanic membrane of the gerbil model of otitis media without manipulation, we present methods of visualizing and color illustrations of the normal tympanic membrane of the Mongolian gerbil, Meriones unguiculatus. These are compared with illustrations of animals with acute experimental otitis media. An artist's rendition of the entire normal gerbil tympanic membrane is presented. These methods and illustrations will enable investigators to more rapidly and easily adopt the Mongolian gerbil as an animal model for studies of otitis media.

Acute Disease↗

PubMed1987

Antibiotic prophylaxis for facial fractures. A prospective, randomized clinical trial.

Although antibiotics are widely used in an attempt to decrease the incidence of infections after facial fractures, no systematic prospective study of their efficacy has been performed. In this study, all adult patients with facial fractures who had not received antibiotics were asked to participate in a clinical trial. There were 101 patients with facial fractures enrolled into the study and randomized prospectively into two groups. One group received no antibiotics. The other group received cefazolin sodium, 1 g intravenously, one hour prior to the surgical procedure, and a similar dose eight hours later. Of the 101 patients enrolled in the study, 79 had mandibular fractures, 18 had zygoma fractures, and four had Le Fort fractures. When all facial fractures were considered, perioperative intravenous cefazolin reduced the incidence of postoperative infections; 42.2% in the no-antibiotic group became infected, and 8.9% in the antibiotic group became infected. On the basis of this study, we conclude that cefazolin, used perioperatively, diminished the incidence of postoperative infections in facial fractures.

Adolescent↗

PubMed1987

Genetic and functional analysis of the otosclerosis-like condition of the LP/J mouse.

The LP/J mouse is the only available genetic model for otosclerosis. The otosclerosis-like condition of the LP/J mouse resembles the human condition in several ways, although there are differences in the two species in the most common locus of the dysplastic otic lesions. The mouse model would be more useful if its auditory dysfunction and genetic inheritance could also be compared with the human disease. Matings of the otosclerosis-like LP/J and the normal CBA/J inbred mice were used to generate F1 and backcross generations. The F1 showed neither functional (electrocochleographic) nor anatomical abnormalities, indicating a recessive nature of the mouse genetic disease. This is in contrast to some reports of dominance (with incomplete penetrance) of otosclerosis in humans. No evidence of X-chromosome-linked genetic influence was found in the mouse, in agreement with the human condition. These interpretations were confirmed in tests of the backcross of the F1 to the CBA/J parental genotype (BC). The anatomical and functional abnormalities were present in some of the backcrosses of the F1 to the LP/J parental genotype (BL). A comparison of bone-conducted and air-conducted electrocochleographic responses provided evidence for both conductive and sensorineural losses in the LP/J and BL mice.

Action Potentials↗

PubMed1986

Bone resorption induced by middle-ear implants.

The pressure produced by expanding aural cholesteatomas has been implicated as a causal factor in the induction of osteoclastic resorption of adjoining bone. This concept is supported by observations of osteoclastic bone resorption produced by expansive tympanic implants. We induced osteoclastic bone resorption in gerbils with tympanic implants of autologous and homologous cartilage, silicone rubber, and Teflon, which exerted pressure only by forces of gravity and surface tension. We estimated that the pressure exerted by these implants ranged from 2.1 X 10(-3) to 8.0 X 10(-3) dynes/sq cm (1.6 to 6.0 mm Hg). These pressures are within the range of pressures known to be exerted by cholesteatomas.

Animals↗

PubMed1986

Osteoclast stimulation by positive middle-ear air pressure.

The mechanism of pathologic bone resorption associated with cholesteatoma is controversial. It is now evident that transmitted pressure is a significant factor in the activation of osteoclasts. Previous studies on the effect of pressure have been confounded by the possible foreign body effect of materials placed into the middle ear to induce the pressure. Positive air pressures were maintained in the middle ear of Mongolian gerbils via implanted Silastic catheters. Histologic evaluation of the ventral bulla wall was performed after pressure had been applied for two weeks. A significant increase in the number density, area density, and size of osteoclasts present in the pressurized bullae was noted at pressures of 4, 6, 10, and 20 mm Hg, but not at 2 mm Hg. We conclude that minute increases in pressure, in the absence of foreign objects, stimulate osteoclastic bone resorption in the middle ear of the gerbil.

Animals↗

PubMed1985

Bacterial flora in spontaneously occurring aural cholesteatomas in Mongolian gerbils.

Bacteria were isolated from 29 Mongolian gerbils, Meriones unguiculatus, with spontaneous aural cholesteatomas. We identified 148 cultures, 44 from the middle ear surface of cholesteatomas and 104 from cholesteatoma contents. We could only identify 63 cultures to the genus level, although we identified 85 cultures as belonging to 21 different species. We found on the surfaces of cholesteatomas representatives of 9 genera, from which 8 species could be identified, and representatives of 19 genera within the cholesteatoma sac, from which 21 species could be identified. The most common bacterial genera isolated were Staphylococcus, Pseudomonas, and Corynebacterium among the aerobic genera, and Bacteroides and Peptococcus among the anaerobic genera. The bacterial flora of gerbilline cholesteatomas was found to be diverse, resembling the flora found to be associated with human cholesteatomas. The flora also resembled the organisms found transitorily within the normal middle ear cavity of gerbils, except for a higher incidence of pseudomonads.

Animals↗

PubMed1985

Myelination in the chorda tympani of the postnatal rat: a quantitative electron microscope study.

We determined the course of myelination of the chorda tympani in rats aged from 4- to 30-days-old, the interval of the most rapid developmental changes in neurophysiological taste responses and behavioral discrimination among chemical stimuli. The overall number of axons in rats aged from 16- to 30-days-old and in mature 120-day-old animals were the same and averaged 1,500. By 30 days, rats had 80% of the total number of myelinated axons observed in adults, but the average thickness of the myelin sheath per neuron and the proportion of the total cross-sectional area that were only about 60% of adult values. Observed increases in myelination closely parallel decreasing response latencies of single chorda tympani fibers to tongue stimulation with salts.

Animals↗

PubMed1985

Bone erosion in experimental cholesteatoma--the effects of implanted barriers.

Mongolian gerbils and man are the only animals known to spontaneously develop bone-eroding aural cholesteatoma. The pathophysiology of bone erosion in cholesteatoma is controversial. The majority of investigators believe that direct contact between cholesteatoma and bone is necessary for erosion to occur. We implanted glass, Silastic, and micropore barriers in the middle ear between the advancing cholesteatoma and cochlea in 50 Mongolian gerbils. The barriers prevented direct contact of cholesteatoma and cochlea but did not inhibit bone erosion. We conclude that transmitted pressure may be responsible for bone erosion in aural cholesteatoma in gerbils.

Animals↗

PubMed1985

Basal lamina breaks in the histogenesis of cholesteatoma.

Aural cholesteatomas may arise in the middle ear by a variety of mechanisms; in some cases it appears that cholesteatomas arise within or behind an intact tympanic membrane. We have observed that microcholesteatomas arise within the tympanic membrane of mongolian gerbils which have keratin accumulations on the lateral surface of the tympanic membrane. An ultrastructural study of the keratinizing epithelium of these animals showed that breaks in the basal lamina allow pseudopods of epithelial cells to extend into the lamina propria and form epithelial cones. The basal lamina later reconstituted itself. Keratinization may occur within these ingrowing cones forming microcholesteatomas. This sequence of events may explain the occurrence of intratympanic cholesteatomas in humans in the absence of invagination or perforation.

Animals↗

PubMed1984

Transcervical transmastoid approach to lesions of the jugular bulb.

Traditional approaches to the jugular bulb principally designed for the extirpation of tumors of the skull base, such as chemodectomas, require a transmastoid approach with transposition of the facial nerve. Such manipulation of the nerve commonly leads to some postoperative impairment. The transmastoid transcervical approach, in which the patient's head is acutely flexed forward, the skull base muscles are separated from their origins, and a retrofacial dissection is performed, permits access to the jugular bulb between the undersurface of the skull and C-1.

Adult↗

PubMed1984

Cellular and subcellular events of bone resorption in human and experimental cholesteatoma: the role of osteoclasts.

An ultrastructural study of the interface between aural cholesteatoma and adjacent bone was performed on specimens obtained from human and experimental gerbilline cholesteatoma. When an enlarging cholesteatoma contacted bone, a large number of monocytes and macrophages accumulated in the area of contact. The intervening middle ear mucosa degenerated and bone erosion occurred. Anatomic evidence is provided which indicates that bone erosion in both human and experimental cholesteatoma occurred as a result of the action of multinucleated osteoclasts. These osteoclasts had the ultrastructural appearance of normal osteoclasts with a well developed ruffled border and large numbers of mitochondria. These cells stained readily with acid phosphatase stains. Although many other mononuclear cells were seen in the vicinity of the eroded bone, only the multi-nucleated osteoclasts were associated with disappearance of the bone surface. Osteoclasts were commonly found in experimental cholesteatoma, but were infrequent in human cholesteatoma biopsies, presumable because patients undergoing cholesteatoma surgery ara often treated with topical installations of corticosteroids which inhibit osteoclasts.

Animals↗

PubMed1984

Hypothermia protects the cochlea from noise damage.

Thresholds of the cochlear action potential were obtained from rodents at euthermic (38 degrees C) and hypothermic (30 degrees and 25 degrees C) rectal temperatures. In the gerbil, low and middle frequency (1-8 kHz) thresholds increased an average of 2.3 dB per degrees C decrease of body temperature; at 16 kHz, 3.5 dB/degrees C; and at 32 kHz, an increase of 4.4 dB/degrees C. In the mouse, these values were: 2-16 kHz, 1.4 dB increase per degrees C decrease; 32 kHz, 2.7 dB/degrees C; 64 kHz, 3.8 dB/degrees C. When subjects maximally susceptible to permanent threshold shift (PTS) at low and middle frequencies (anesthetized, immature mice) were exposed to 115 dB noise, hypothermia reduced PTS at these most susceptible frequencies (2-16 kHz). When awake adult mice were exposed to this noise, hypothermia protected them from PTS at their most vulnerable frequency (32 kHz).

Animals↗

PubMed1984

Superior based trapezius flap.

The most revolutionary innovation in reconstructive surgery of the past decade is the development of the musculocutaneous flaps. These flaps permit the reconstruction of large head and neck defects in one stage. They carry an excellent reliable blood supply and the inclusion of the underlying muscle adds sorely needed bulk to the resected area. The trapezius musculocutaneous flap is one of the most versatile. Its color and texture match for facial reconstruction is excellent. Moreover, the pliability of the cutaneous component lends itself well to lining the oral cavity and the oropharynx. The trapezius musculocutaneous flap is an outstanding advance in head and neck reconstructive surgery. The discovery that it can be successfully pedicled superiorly greatly enhances its versatility.

Aged↗

PubMed1983

Otosclerotic lesions in the inbred LP/J mouse.

Inbred LP/J mice develop abnormal bony lesions that are grossly and histologically similar to the lesions of human otosclerosis. This is the first known occurrence of spontaneous otosclerosis-like lesions in an animal. As in the human disease, these lesions impair audition by immobilizing the ossicles of the middle ear. The LP/J mouse may be an animal model for this common human disease.

Animals↗

PubMed1983

Age-related increase of spontaneous aural cholesteatoma in the Mongolian gerbil.

The Mongolian gerbil is the only non-human animal known to spontaneously develop aural cholesteatomas. In this rodent, both the prevalence of spontaneous cholesteatomas and the resultant peripheral auditory evoked potential threshold increases from 6 to 18 months of age. By 24 months, the end of their median life span, other factors begin to affect auditory function. Therefore, the electrocochleographic technique can be efficiently used to nontraumatically trace the development of the cholesteatoma from 6 to 18 months, providing an experimental method for evaluating techniques to prevent or retard the growth of aural cholesteatomas.

Aging↗

PubMed1983

A histomorphometric study of the effect of chronic vitamin A deficiency on the circumvallate papilla of the rat.

Although a deterioration of taste sensitivity is known to occur during severe vitamin A depletion, the structural changes in the taste buds themselves have not been described. Circumvallate papillae from rats deprived of vitamin A were examined histomorphometrically at intervals, and changes in the gustatory apparatus were quantitated. The cross-sectional area of the circumvallate trenches increases 30-fold because of keratin accumulation when vitamin A deficiency is extreme. After 190 days on a vitamin A-free diet, 38% of rats had no detectable taste buds and the remaining taste buds appeared atrophied. The involution of the taste buds may be the result of keratin buildup in the adjacent trench or a direct consequence of vitamin A deficiency. The atrophy of the gustatory apparatus during vitamin A deficiency and the consequent presumed loss of taste sensation may contribute to a diminished interest in food and the subsequent protein-calorie malnutrition seen in vitamin A-deficient populations.

Animals↗