PubMed Health⌕ Search

Biomedical subjects

B Gantz

Publications and source records attributed to B Gantz.

11 recordsLinked to original sources
PubMed1999

A comparison of language achievement in children with cochlear implants and children using hearing aids.

English language achievement of 29 prelingually deaf children with 3 or more years of cochlear implant (CI) experience was compared to the achievement levels of prelingually deaf children who did not have such CI experience. Language achievement was measured by the Rhode Island Test of Language Structure (RITLS), a measure of signed and spoken sentence comprehension, and the Index of Productive Syntax (IPSyn), a measure of expressive (signed and spoken) English grammar. When the CI users were compared with their deaf age mates who contributed to the norms of the RITLS, it was found that CI users achieved significantly better scores. Likewise, we found that CI users performed better than 29 deaf children who used hearing aids (HAs) with respect to English grammar achievement as indexed by the IPSyn. Additionally, we found that chronological age highly correlated with IPSyn levels only among the non-CI users, whereas length of CI experience was significantly correlated with IPSyn scores for CI users. Finally, clear differences between those with and without CI experience were found by 2 years of post-implant experience. These data provide evidence that children who receive CIs benefit in the form of improved English language comprehension and production.

Achievement↗
PubMed1998

Pseudoepitheliomatous hyperplasia versus squamous cell carcinoma of the external auditory canal.

Four case reports are presented to demonstrate the clinical and histopathologic similarity of pseudoepitheliomatous hyperplasia (PH) to squamous cell carcinoma (SCC) in the external auditory canal (EAC). In all four cases the original report of SCC on a biopsy specimen of an EAC lesion was corrected on review to PH. In one patient conservative management resulted in resolution of the EAC lesion. A second patient underwent radiation therapy and partial temporal bone resection with no SCC found in the surgical specimen. A third patient's ear canal had healed with conservative treatment and repeated biopsy revealed no malignancy. After a 6-year symptom-free interval, she developed invasive SCC with bone involvement that required surgery and radiation treatment. A fourth patient underwent a sleeve resection of the skin of the EAC that proved to be PH, and no evidence of SCC was found. A thoughtful clinical history, careful physical examination, response to conservative treatment, and close communication with the pathologist should be exercised in the evaluation of EAC lesions.

Adult↗
PubMed1996

Phenotypic variability in monozygotic twins with neurofibromatosis 2.

Mutations in the neurofibromatosis 2 (NF2) tumor suppressor gene on chromosome 22q12 cause a clinically variable autosomal dominant syndrome characterized by bilateral vestibular schwannomas (VSs), other nervous system tumors, and early onset lenticular cataracts. We studied three pairs of monozygotic (MZ) twins with NF2, all with bilateral VSs, to separate genetic from nongenetic causes of clinical variability. The evaluation included gadolinium-enhanced high-resolution magnetic resonance imaging of the head and spine, neuro-ophthalmic examination with slit lamp, physical examination, and zygosity testing with microsatellite markers. Each MZ pair was concordant for general phenotypic subtype (mild or severe) and often for the affected organ systems. However, the MZ pairs were discordant for some features of disease presentation or progression. For example, all three pairs were discordant for presence or type of associated cranial tumors. We hypothesize that phenotypic differences between NF2 MZ twins are at least partly due to stochastic processes, such as the loss of the second NF2 allele or alleles of other genes.

Adult↗
PubMed1992

Specific inhibition of Physarum polycephalum DNA-polymerase-alpha-primase by poly(L-malate) and related polyanions.

Poly(L-malate) is an unusual polyanion found in nuclei of plasmodia of Physarum polycephalum. We have investigated, by enzymatic and fluorimetric methods, whether poly(L-malate) and structurally related polyanions can interact with DNA-polymerase-alpha-primase complex and with histones of P. polycephalum. Poly(L-malate) is found to inhibit the activities of the DNA-polymerase-alpha-primase complex and to bind to histones. The mode of inhibition is competitive with regard to DNA in elongation and noncompetitive in the priming of DNA synthesis. Spermidine, spermine, and histones from P. polycephalum and from calf thymus bind to poly(L-malate) and antagonize the inhibition. The polyanions poly(vinyl sulfate), poly(acrylate), poly(L-malate), poly(D,L-malate), poly(L-aspartate), poly(L-glutamate) have been examined for their potency to inhibit the DNA polymerase. The degree of inhibition is found to depend on the distance between neighboring charges, given by the number of atoms (N) interspaced between them. Poly(L-malate) (N = 5) and poly(D,L-malate) (N = 5) are the most efficient inhibitors, followed by poly(L-aspartate) (N = 6), poly(acrylate) (N = 3), poly(L-glutamate) (N = 8), poly(vinyl sulfate) (N = 3). It is proposed that poly(L-malate) interacts with DNA-polymerase-alpha-primase of P. polycephalum. According to its physical and biochemical properties, poly(L-malate) may alternatively function as a molecular chaperone in nucleosome assembly in the S phase and as both an inhibitor and a stock-piling agent of DNA-polymerase-alpha-primase in the G2 phase and M phase of the plasmodial cell cycle.

Animals↗
PubMed1990

Electrically evoked whole-nerve action potentials: data from human cochlear implant users.

This study describes a method for recording the electrically evoked, whole-nerve action potential (EAP) in users of the Ineraid cochlear implant. The method is an adaptation of one originally used by Charlet de Sauvage et al. [J. Acoust. Soc. Am. 73, 615-627 (1983)] in guinea pigs. The response, recorded from 11 subjects, consists of a single negative peak that occurs with a latency of approximately 0.4 ms. EAP input/output functions are steeply sloping and monotonic. Response amplitudes ranging up to 160 micro V have been recorded. Slope of the EAP input/output function correlates modestly (approximately 0.6-0.69) with results of tests measuring word recognition skills. The refractory properties of the auditory nerve were also assessed. Differences across subjects were found in the rate of recovery from the refractory state. These findings imply that there may be difference across subjects in the accuracy with which rapid temporal cues can be coded at the level of the auditory nerve. Reasonably strong correlations (approximately 0.74-0.85) have been found between the magnitude of the slope of these recovery curves and performance on tests of word recognition.

Cochlear Implants↗
PubMedDate not supplied

Nasopharyngeal angiofibroma.

Based on this patient's history and the imaging studies, all the consultants agree that they are dealing with a juvenile nasopharyngeal angiofibroma. They agree that a biopsy is not necessary. However, angiography would be obtained by 2 physicians (Drs. Seid and Weber). When treating an extensive JNA, the consultants differ in their approaches. One favors a lateral infratemporal fossa approach (Dr. Gantz), but the others favor a combined approach (Drs. Seid and Weber). In this particular case, 2 experts favor resection (Drs. Gantz and Weber), but one would irradiate (Dr. Seid). There is also disagreement regarding the severity of morbidity. Minor problems include conductive hearing loss, paresis of the third division of the fifth cranial nerve (Dr. Gantz), and a transient facial nerve paralysis (Dr. Weber). They are more concerned about the long-range problems from skull-base radiotherapy including brain-stem compromise, pituitary dysfunction, and radiation-induced malignancies. No one suggests chemotherapy or multimodal therapy. Regarding the natural history of JNA, the views range from no spontaneous regression (Dr. Gantz), gradual involution over time (Dr. Seid), or an indolent nature that requires tapering the treatment to the benign nature of the process (Dr. Weber).

Adolescent↗
PubMedDate not supplied

Multichannel cochlear implants in partially ossified cochleas.

Deposition of bone within the fluid spaces of the cochlea is encountered commonly in cochlear implant candidates and previously has been considered a relative contraindication to the use of multichannel intracochlear electrodes. This contraindication has been based on possible mechanical difficulty with electrode insertion as well as uncertainty about the potential benefit of the multichannel device in the patient. Fifteen profoundly deaf patients with partial ossification of the basal turn of the cochlea received implants with long intracochlear electrodes (11, Nucleus; 1, University of California at San Francisco/Storz; and 3, Symbion/Inneraid). In 11 cases, ossification had been predicted preoperatively by computed tomographic scan. Electrodes were completely inserted in 14 patients, and partial insertion was accomplished in one patient. All patients currently are using their devices and nine of 12 postlingually deaf patients have achieved some degree of open-set speech discrimination. This series demonstrates that in experienced hands, insertion of long multichannel electrodes into partially ossified cochleas is possible and that results are similar to those achieved in patients who have nonossified cochleas.

Adolescent↗