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Biomedical subjects

T Twomey

Publications and source records attributed to T Twomey.

10 recordsLinked to original sources
PubMed1997

Electrode and device problems: manifestation and management.

A total of 119 children were implanted with the Nucleus 22 implant on the Nottingham program by March 1996. Twenty-five (i.e. 21%) of these had an electrophysiologically confirmed fault on at least 1 channel and 6 (i.e. 5%) had experienced total device failure. How these problems were first manifested and what the subsequent effects were on the child and family were determined by means of questionnaires and detailed examination of clinical notes. Our findings indicated that 76% of all internal device faults were initially detected in tuning or electrophysiological measurement. All parents expressed deep anxiety about the threat of device failure; cases of total failure occurring over a long period of time resulted in the greatest distress and effect on the family. Recommendations are made for companies to assist clinics in minimizing such effects.

Anxiety↗
PubMed1996

Intraoperative electrophysiological and objective tests after cochlear re-implantation in a young child.

The electrically evoked auditory brainstem response (EABR) and stapedius reflex threshold (ESRT) are routinely recorded during implant surgery with the Nucleus 22 channel cochlear implant in the Nottingham Paediatric Cochlear Implant Programme and are extremely valuable in the management of young implanted children. These intraoperative tests were carried out in a young child on the occasion of the first implantation and then after re-implantation 17 months later following malfunction of the first device. The surgical experiences of the first implantation and the re-implantation were both straightforward. Recordings of the intraoperative EABR and ESRT were typical of the expected pattern of responses on both occasions and there was only a small reduction in threshold sensitivity after re-implantation. These investigations provide valuable objective information to support and assist with the management of re-implantation in a young child.

Child, Preschool↗
PubMed1995

Characterization of an acid-resistant mutant of foot-and-mouth disease virus.

A foot-and-mouth disease virus mutant which is stable at pH 6.4 has been isolated from a virus of serotype A. In contrast to the parent (P) virus, which gave a mixture of large and small plaques in BHK21 cells and in a bovine kidney cell line, the acid-resistant (AR) virus gave small plaques which did not increase markedly in size after 24 hr. The infectivity titer of the acid-resistant virus was about 100-fold lower in suckling mice than in BHK21 cells, whether the inoculation was made intraperitoneally or intracerebrally, whereas the parent virus gave similar titers in both systems. Furthermore, in mice the AR virus reached its end point two to three times more slowly. The diameter of the AR virus was almost 20% less than that of the P virus and it had a more distinct topography, but the two viruses cosedimented in sucrose gradients. However, the buoyant density in CsCl of the AR virus was slightly lower (1.42 compared with 1.43 g/cc) in coruns. The RNAs and capsid proteins of the two viruses gave similar profiles in sucrose gradients and by SDS-PAGE, respectively. However, isoelectric focusing of the capsid proteins revealed considerable differences between the two viruses. Whereas the P virus gave four protein bands, corresponding to VP1-VP4, the AR virus gave one band for VP4, two for VP3, two for VP2, and four for VP1. Sequence analysis of the genes coding for the capsid protein regions of the two viruses showed four changes (one silent), resulting in an Ala-3-->Ser substitution in VP1 and Glu-131-->Lys and Asp-133-->Ser substitutions in VP2.

Animals↗
PubMed1995

Structure and immunogenicity of experimental foot-and-mouth disease and poliomyelitis vaccines.

The physico-chemical properties and immunogenicity of experimental vaccines against foot-and-mouth disease (FMD) and poliomyelitis, prepared by treatment of the viruses with N-acetylethyleneimine (AEI), formaldehyde or neutral red, have been studied. None of these reagents affects the rate of sedimentation of the particles or their reaction with antibody against the major immunogenic sites. FMD vaccines prepared by inactivation with AEI or neutral red, behaved like the untreated virus, in that they were disrupted on lowering the pH below 7. The RNA of the AEI-inactivated virus was degraded into slowly sedimenting molecules. Unlike AEI-inactivated virus, from which all the RNA could be extracted with phenol-SDS, the recovery from the neutral red inactivated virus was variable and was sometimes as low as 40%; this RNA gave a heterogenous profile in sucrose gradients. The capsid proteins in the AEI preparation migrated in SDS-PAGE to the same positions as those of untreated virus, but in the neutral red preparation there was evidence of cross-linking. In contrast, the formaldehyde-inactivated vaccine was stable below pH 7 and the RNA could not be released by extraction with phenol-SDS at pH 5, because the capsid proteins had become cross-linked and/or linked to the RNA. As with foot-and-mouth disease virus (FMDV), poliovirus which had been inactivated with formaldehyde did not release its RNA on extraction with phenol-SDS and the capsid proteins were also cross-linked. Surprisingly, although AEI cleaved the viral RNA slowly in situ, the virus was no longer infectious after 6 h. Neutral red did not reduce the infectivity of the virus. All of the preparations gave similar levels of neutralizing antibody after a single inoculation. The high levels obtained with the formaldehyde-inactivated vaccines have implications for the processing of fixed particles by the antigen-presenting cells.

Animals↗
PubMed1994

Clinical evaluation and test-retest reliability of the IHR-McCormick Automated Toy Discrimination Test.

The IHR-McCormick Automated Toy Discrimination Test (ATT) measures the minimum sound level at which a child can identify words presented in quiet in the sound field. This 'word-discrimination threshold' provides a direct measure of the ease with which a child can identify speech and a surrogate measure of auditory sensitivity. This paper describes steps taken to maximize the test-retest reliability of the ATT and to enable it to measure word-discrimination thresholds in noise as well as in quiet. It then describes the results of a clinical evaluation of the ATT in which paediatric audiologists measured word-discrimination thresholds in quiet from 215 successive attendees (in the age range 2 to 13 years) at a paediatric audiology clinic presenting over a 2-month period. When children with atypical cognition or delayed development of language were excluded, 72% of the children provided two word-discrimination thresholds and 83% provided at least one word-discrimination threshold. Children who failed to provide word-discrimination thresholds were generally younger than four years of age. Although a few children who could not perform pure-tone or warble-tone audiometry managed to provide word-discrimination thresholds, most children who could perform the ATT could also perform pure-tone audiometry. The average pure-tone threshold in the better-hearing ear could be predicted from the word-discrimination threshold with a 95% confidence interval of +/- 13 dB. The test-retest reliability of the ATT was measured in two ways. First, to enable comparison with published results, the within-subjects standard deviation of word-discrimination thresholds was calculated. It varied as a function of age and degree of impairment, but was never worse than 3.3 dB. Children of four years of age and older displayed the adult reliability of 2.3 dB. Second, the variability of absolute differences between word-discrimination thresholds was calculated. It was such that a change of 7 dB between two runs of the test (e.g. aided and unaided) would be expected to occur by change less than one time in 20. These results extend previous evaluations of the ATT to a clinically representative population and confirm that word-discrimination thresholds provide a useful complement to warble-tone and pure-tone audiometry.

Adolescent↗
PubMed1989

The IHR-McCormick Automated Toy Discrimination test--description and initial evaluation.

McCormick's Toy Discrimination test allows a skilled audiologist to obtain word discrimination thresholds in quiet from children with mental ages of 2 years and above. A semi-automatic version of the test has been developed and evaluated by testing the hearing of 46 children and five adults. The equipment for the new version of the test both produces the stimuli and scores the responses, thereby reducing the burden on the tester. It is reliable and allows greater sensitivity than the manual test as well as solving problems of standardization and calibration.

Auditory Threshold↗
PubMed1986

O.R. custom packs: no easy answers.

The use of custom sterile packs continues to grow in popularity as hospitals look for different ways to reduce the cost of providing health care services. Mounting evidence appears to indicate, however, that the real beneficiaries of custom packs and the vendors themselves.

California↗