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Biomedical subjects

M J Penner

Publications and source records attributed to M J Penner.

At least 19 recordsLinked to original sources
PubMed1999

The in vitro elution characteristics of antibiotic-loaded CMW and Palacos-R bone cements.

An in vitro study was carried out comparing the elution characteristics of Palacos-R and CMW acrylic cements. Three groups of 6 antibiotic-loaded cement disks were prepared, incorporating 1.0 g vancomycin and 2.4 g tobramycin per 40 g packet of cement. Palacos-R bone cement was used for group 1, CMW 1 for group 2, and CMW 3 for group 3. The disks were placed in saline baths for 9 weeks. The baths were periodically sampled and elution rates calculated. CMW 1 released 24% less tobramycin and 36% less vancomycin than Palacos-R over the total study period (P < .05). CMW 3 released 34% less tobramycin and 38% less vancomycin than Palacos-R (P < .05). There was no significant difference in antibiotic release between CMW 1 and CMW 3. The in vitro elution characteristics of Palacos-R are superior to CMW.

Acrylic Resins↗
PubMed1998

Role and results of segmental allografts for acetabular segmental bone deficiency.

Acetabular reconstruction in both primary and revision hip arthroplasty often requires reconstruction of deficient acetabular bone stock. The exact role of allografts remains controversial. Published results of structural allografting are presented. Recent literature supports the use of segmental allografts for reconstruction of large segmental and combined defects.

Acetabulum↗
PubMed1998

A new method for the automated detection of spontaneous otoacoustic emissions embedded in noisy data.

There is, as yet, no universally agreed upon method for the detection of spontaneous otoacoustic emissions (SOAEs). In this paper, we augment extant techniques by presenting a new automated approach. The new procedure reliably labels the spectral peaks as SOAEs, rejects noisy data such as that due to body movements or breathing, provides a subject-specific measure of the probability that a particular peak is erroneously identified as a SOAE, and can be accomplished on-line. Comparison of results with this new approach and with methods undertaken previously in this laboratory and elsewhere are made. The estimated prevalence of SOAEs for the new method is as large as that for any method previously proposed.

Acoustic Stimulation↗
PubMed1997

Prevalence of spontaneous otoacoustic emissions in adults revisited.

The potential influence of spectral analysis factors on estimates of the prevalence of spontaneous otoacoustic emissions (SOAE) was explored. The detection of a SOAE was influenced by two spectral factors: (1) the frequency resolution of the spectrum, and (2) the number of spectral averages. For 15 different combinations of these two factors, the estimate of the prevalence of SOAEs for females ranged from 64 to 81% and, for males, from 39 to 55%. Combining across all 15 combinations, 83% of the females and 62% of the males were judged to have SOAEs. These results provide a context for understanding the inconsistencies in previous estimates of the prevalence of SOAEs and underscore the need to employ many different spectral analyses because some SOAEs are only detected when the spectral analyses are suitably tailored.

Adult↗
PubMed1996

Elution characteristics of vancomycin and tobramycin combined in acrylic bone-cement.

Combining two antibiotics in antibiotic-loaded bone-cement is common in clinical practice. As the effect this has on elution characteristics is unknown, an in vitro quantitative elution study was carried out. Three groups of five antibiotic-loaded cement disks were prepared and placed in individual saline baths for 5 weeks. The elution of tobramycin from the disks in the study group (containing 2.4 g tobramycin and 1.0 g vancomycin per 40-g packet of Palacos-R cement powder [Smith & Nephew Orthopaedics, Memphis, TN]) was increased by 68% over that of the tobramycin control disks (2.4 g tobramycin only) (P = .024). The release of vancomycin from the study group disks was increased by 103% over the vancomycin control disks (1.0 g vancomycin only) (P = .007). Combining two antibiotics in bone-cement improves elution of both antibiotics in vitro and may translate into enhanced elution in vivo.

Anti-Bacterial Agents↗
PubMed1996

The emergence and disappearance of one subject's spontaneous otoacoustic emissions.

OBJECTIVE: This paper documents the appearance and disappearance of multiple, intense spontaneous otoacoustic emissions (SOAEs) in one subject who previously had no measurable SOAEs. DESIGN: A subject, who had no spontaneous otoacoustic emissions (SOAEs) from 4/24/93 to 5/24/93, displayed 10 SOAEs on 5/26/93 (day 1). The SOAEs of the subject were tracked for 342 days. RESULTS: On day 85, the SOAEs had all vanished. Thereafter, no stable SOAEs appeared. However, on days 94 and 99 one SOAE was intermittently measured in the left ear. CONCLUSIONS: These data seem to indicate that some SOAEs may be caused by reversible disturbances of active transduction mechanisms, and that not all SOAEs are heritable. Because the subject had been exposed to loud music on the night preceding the emergence of the SOAEs, the putative cause of the SOAEs may have been exposure to loud sound.

Adolescent↗
PubMed1995

Frequency variation of spontaneous otoacoustic emissions during a naturally occurring menstrual cycle, amenorrhea, and oral contraception: a brief report.

OBJECTIVE: The frequencies of one subject's spontaneous otoacoustic emissions (SOAEs) were tracked intermittently for 295 days. DESIGN: The first 40 days encompassed a normal menstrual cycle. During the next 186 days, the subject exhibited amenorrhea. For the last 69 days, she took oral contraceptives prescribed by her doctor to reestablish menstrual function. RESULTS: Anovulation, as evidenced by amenorrhea or induced by oral contraception, reduced the fluctuation of SOAE frequencies relative to the naturally occurring menstrual cycle. CONCLUSIONS: Future research might fruitfully be aimed at monitoring SOAE frequencies in humans and animals to determine whether the fluctuations can provide a noninvasive measure of the functioning of the pituitary-gonadal axis.

Adult↗
PubMed1994

Covariation of binaural, concurrently-measured spontaneous otoacoustic emissions.

Simultaneous recordings of binaural spontaneous otoacoustic emissions (SOAEs) were made for 2 female subjects. For SOAEs below about 3.6 kHz measured within a testing session, the frequencies of nearby monaural and binaural SOAEs tended to move in tandem, whereas widely separated SOAEs did not. Across many testing sessions spanning a menstrual cycle, all monaural and binaural SOAE frequencies shifted in tandem. Possible mechanisms consistent with these results are discussed.

Acoustic Stimulation↗
PubMed1994

Simultaneous measurement of tinnitus pitch and loudness.

OBJECTIVE: Simultaneous measures of the frequency and level of a pure tone matching the predominant pitch and loudness of tinnitus were obtained using four interleaved staircases. DESIGN: Two staircases in a forced-choice procedure tracked two frequencies, one higher and one lower than the predominant pitch of the tinnitus, while two staircases tracked two levels, one louder and one softer than the tinnitus. RESULTS: The standard deviation of the pitch matches to tinnitus using the forced-choice procedure with four staircases (4SFC) exceeded that from a double staircase (2SFC) task in which the level of the matching tone was fixed, whereas the 2SFC and 4SFC tasks had similar SDs for loudness matches to tinnitus when the frequency of the matching tone was fixed and for matches to the pitch or loudness of external tones. As the level of the tone matching the tinnitus pitch in the 4SFC task increased relative to that of the 2SFC task, so did its frequency. CONCLUSION: These data may be interpreted as indicating that tinnitus is a fluctuant signal, and that matches of pure tones to tinnitus are not single-valued.

Acoustic Stimulation↗
PubMed1994

Covariation of tinnitus pitch and the associated emission: a case study.

Tinnitus in one female subject was found to be related to numerous (as many as 21) bilateral spontaneous otoacoustic emissions. The association of tinnitus and spontaneous otoacoustic emissions was empirically supported by the masking/suppression demonstration. The subject reported that her tinnitus occurred primarily in her right ear, which had linked, quasi-stable spontaneous otoacoustic emissions not found contralaterally. During one menstrual cycle, a pure tone was adjusted to match the predominant tinnitus pitch. The frequency of the tone generally followed the day-to-day shifts in the frequency of the associated spontaneous otoacoustic emission. The frequencies of these tones were a local minimum near the onset of menstruation, reaching a local maximum after menstruation.

Acoustic Stimulation↗
PubMed1993

Spontaneous otoacoustic emissions: measurement and data.

Sounds from the ear canal were measured and then analyzed off-line. A peak-picking algorithm located spectral maxima which might be designated as spontaneous otoacoustic emissions (SOAEs). The output from a 0.5-cc syringe, used to stimulate the volume of the ear canal, was also measured, analyzed and used to approximate the false-alarm rate of the measurement system. SOAE prevalence estimates depended on the false-alarm rate, just as the hit rate in a yes-no task does. With a false-alarm rate of zero, trends that have been found to be significant in the pooled results of other surveys were replicated: more SOAEs in the right ear, more SOAEs in females, and increased probability that the contralateral ear has an SOAE if the ipsilateral ear has an SOAE. In addition, many SOAEs failed to be detected in consecutive spectral analyses because they fluctuated in level.

Acoustic Stimulation↗
PubMed1993

Synthesizing tinnitus from sine waves.

Four subjects mimicked the sensation caused by their tinnitus with a complex sound pattern consisting of the sum of sine waves. Matches to the predominant pitch of the tinnitus were generally near one component of the imitation tinnitus, although the predominant pitch of the imitation was not necessarily near the predominant pitch of the genuine tinnitus. Subjects rated the similarity of their tinnitus and all combinations of the tones constituting the imitation and, as a control, also rated the similarity of the imitation and all combinations of its individual components. Although subjects rated the imitation tinnitus as identical to itself when all components of the imitation were present, the imitation was never rated as identical to the genuine tinnitus. However, increasing the number of components in the imitation tinnitus made it more similar to the bona fide tinnitus. Thus, multiple tones provide a better tinnitus imitation than does a single pure tone.

Audiometry, Pure-Tone↗
PubMed1992

Consistent within-session measures of tinnitus.

Two psychophysical methods, a method of adjustment (MOA) and a forced-choice double-staircase adaptive procedure (FCDS) (Jesteadt, 1980), were used to measure the predominant pitch and loudness of tinnitus for 11 subjects during one test session. The FCDS within-session variability of matches to tinnitus pitch was smaller than for the MOA and comparable to the within-session variability obtained when the FCDS procedure was used to match objective stimuli that approximated the frequency and level of the tinnitus. The within-session variability of matches to tinnitus loudness was nearly identical for the FCDS and the MOA and comparable to the within-session variability obtained when the FCDS procedure was used to match objective stimuli that approximated the frequency and level of the tinnitus. For 3 subjects who participated in 20 sessions, the two psychophysical methods produced correlated measures of tinnitus that tracked each other between sessions. This suggests that tinnitus may be stable within a brief time span but fluctuant in the long run.

Adult↗
PubMed1992

Indications for aspirin as a palliative for tinnitus caused by SOAEs: a case study.

This paper explores the effect of aspirin on the tinnitus of one patient for whom two contralateral spontaneous otoacoustic emissions (SOAEs) caused binaural tinnitus. The relation between the SOAEs and tinnitus was explored during a preliminary testing session, after which the SOAEs were measured for 7 days. During days 1, 2, 5, 6 and 7 of the trial, a placebo (two 50-mg tablets of ascorbic acid) was administered four times per day. During days 3 and 4, a drug (two 300-mg tablets of aspirin) was administered four times per day. During day 2, the right ear's SOAE was low level and labile, sometimes disappearing into the noise floor. The effect of aspirin on an emission which is not consistently observed, cannot be assessed so this report focuses primarily on the left ear. During days 1 and 2, the SOAE in the left ear was present and the tinnitus was audible. By day 3 (after 2.4 g of aspirin), the SOAE in the left ear had been abolished, and the tinnitus was not audible. On the fifth day (24 hours after the last aspirin), both the SOAE and the tinnitus in the left ear had returned. There were no reported side-effects of the aspirin. Thus, aspirin seemed to provide an acceptable palliative for this patient's SOAE-caused tinnitus.

Aspirin↗
PubMed1992

Measures of tinnitus: step size, matches to imagined tones, and masking patterns.

Measures of the pitch (0.2% step) and loudness (2 dB step) of tinnitus were obtained using a forced-choice double-staircase procedure. In the first experiment, for seven subjects with tinnitus, the difference limen of pitch and loudness matches made to tinnitus within a single block of trials was not significantly different from that of the same measurements made to comparable external stimuli. In the second experiment, subjects matched the pitch of real and imagined tones. For 3 of 7 subjects with tinnitus and for 2 of 14 normal-hearing subjects, the difference limens were nearly equal. In the first experiment, therefore, three of the subjects with tinnitus might have matched to an imagined tone and not to their tinnitus. In the third experiment, thresholds of tones near the presumed tinnitus frequency were measured. Thresholds were approximately equal in the presence of the tinnitus. However, in the presence of a masking tone at the presumed tinnitus frequency and level, thresholds were unequal. Thus, tinnitus did not behave as a tonal masker.

Acoustic Stimulation↗
PubMed1990

An estimate of the prevalence of tinnitus caused by spontaneous otoacoustic emissions.

Prototypical experimental tests for linking spontaneous otoacoustic emissions with disruptive tinnitus have been described previously. Using similar experimental tests on 96 tinnitus sufferers, an estimate is made here of the prevalence of tinnitus caused by spontaneous otoacoustic emissions: the 95% confidence limits of this estimate are 1.11% and 9.05%.

Cochlea↗
PubMed1989

Aspirin abolishes tinnitus caused by spontaneous otoacoustic emissions. A case study.

A series of experimental tests are presented indicating that numerous spontaneous otoacoustic emissions (SOAEs) are likely to provide the basis of monaural tinnitus for one female patient. For this patient, (1) the tinnitus disappeared only when all SOAE components were suppressed, (2) with all but one emission suppressed, the frequency of an external tone said to match the pitch of the tinnitus was close to the frequency of the unsuppressed SOAE, and (3) the isomasking contour for the tinnitus was frequency specific. All these tests indicated that the patient was likely to be hearing SOAEs. During subsequent aspirin administration, her SOAEs disappeared and her perception of her tinnitus was radically altered. The tinnitus was no longer described as monaural and "tonal" but instead was described as being "noise in the head."

Aspirin↗