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Biomedical subjects

L E Davis

Publications and source records attributed to L E Davis.

At least 307 records · Page 17Linked to original sources
PubMedDate not supplied

Comparative experimental viral labyrinthitis.

Because of difficulties in studying acute deafness and vertigo in humans, animal models of viral labyrinthitis have played an important role in increasing our understanding of how viruses damage the inner ear. Investigators have been able to correlate viral labyrinthine infection to histopathologic changes and electrophysiologic consequences in experimental animals. Experimental viral labyrinthitis studies have convincingly demonstrated the selective vulnerability of inner ear cell types to different viruses. These findings are relatively consistent across animal species for many viruses. By understanding the pathogenesis of viral labyrinthitis in an animal model, we may learn how better to prevent or treat virus-induced deafness and vertigo in humans.

Animals↗
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Intralabyrinthine osteogenesis in Cogan's syndrome.

Temporal bones from a 64-year-old man who had Cogan's syndrome were examined by light microscopy. Although tissues of the middle ear appeared unremarkable, extensive ectopic bone formation was observed bilaterally in the inner ear membranous labyrinth. Such osteogenesis completely obliterated the cochlear compartments apically. Only the scala tympani compartment of the basal cochlear turn remained patent. Ectopic bone tissue was observed also in the vestibular semicircular canals. Marked degeneration of eighth nerve fibers and associated ganglion cells also was observed. To our knowledge, this report represents only the fourth temporal bone findings of Cogan's syndrome and demonstrates a more advanced pathologic state of inner ear pathology than those reported previously.

Adult↗
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An MRI study of lumbar puncture headaches.

We studied 11 patients undergoing a routine lumbar puncture to determine if there were cerebrospinal fluid leaks at the puncture site and whether the maximum volume of leakage correlates with a lumbar puncture headache. Patients completed a headache questionnaire before and after the lumbar puncture. Limited magnetic resonance imaging of the lumbar spine was obtained 8 to 36 hours after the lumbar puncture and two patients also had later imaging. In a blinded fashion, the largest diameter of cerebrospinal fluid leakage into the paraspinous area was determined from T2 weighted magnetic resonance images and the maximum possible fluid volume was calculated. Six patients had a small cerebrospinal fluid leakage (< 10 mL), two had a medium leakage (10 to 110 mL), and three had a large leakage (> 110 mL). The volume of cerebrospinal fluid leakage did not correlate with occurrence of a lumbar puncture headache. The study demonstrates that cerebrospinal fluid usually leaks into the paraspinous area after a lumbar puncture, but the volume of escaped fluid does not correlate with a lumbar puncture headache.

Cerebrospinal Fluid↗
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Hemodynamic effects of calcium gluconate administered to conscious horses.

Calcium gluconate was administered to conscious horses at 3 different rates (0.1, 0.2, and 0.4 mg/kg/min for 15 minutes each). Serum calcium concentrations and parameters of cardiovascular function were evaluated. All 3 calcium administration rates caused marked increases in both ionized and total calcium concentrations, cardiac index, stroke index, and cardiac contractility (dP/dtmax). Mean arterial pressure and right atrial pressure were unchanged; heart rate decreased markedly during calcium administration. Ionized calcium concentration remained between 54% and 57% of total calcium concentration throughout the study. We conclude that calcium gluconate can safely be administered to conscious horses at 0.1 to 0.4 mg/kg/min and that administration will result in improved cardiac function.

Animals↗
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Experimental viral infections of the inner ear. II. Simian virus 40 induced tumors of the temporal bone.

Pathological and virological studies were performed on temporal bones of 23 hamsters which developed tumors subsequent to neonatal inoculation of simian virus 40 (SV40). Four to five months after viral inoculation, 22 hamsters developed undifferentiated sarcomas in the subcutaneous space adjacent to the temporal bone. Nine tumors invaded the temporal bone, occassionally extending to the subarachnoid space but not to the inner ear. Choroid plexus papillomas developed in four animals, with one tumor demonstrating invasion of the cochlear aqueduct, internal auditory canal, and cochlear modiolus. Cells grown from a sarcoma and a choroid plexus papilloma contained tumor antigen and established that the tumors were SV40 virus induced.

Animals↗
PubMedDate not supplied

Cytomegalovirus isolation from a human inner ear.

Cytomegalovirus (CMV) infection of the fetus has been associated with congenital deafness or hearing loss. This association has previously been based on clinical or pathological studies. We report an infant who died with the congenital CMV syndrome in which CMV was isolated from the perilymph of the inner ear providing additional evidence that this virus can infect the labyrinth.

Cytomegalovirus↗