Ultrasonically enhanced vancomycin activity against Staphylococcus epidermidis biofilms in vivo.

Infection of implanted medical devices by Gram-positive organisms such as Staphylococcus ssp. is a serious concern in the biomaterial community. In this research the application of low frequency ultrasound to enhance the activity of vancomycin against implanted Staphylococcus epidermidis biofilms was examined. Polyethylene disks covered with a biofilm of S. epidermidis were implanted subcutaneously in rabbits on both sides of their spine. The rabbits received systemic vancomycin for the duration of the experiment. Following 24 h of recovery, one disk was insonated for 24 or 48 h while the other was a control. Disks were removed and viable bacteria counted. At 24 h of insonation, there was no difference in viable counts between control and insonated biofilms, while at 48 h of insonation there were statistically fewer viable bacteria in the insonated biofilm. The S. epidermidis biofilms responded favorably to combinations of ultrasound and vancomycin, but longer treatment times are required for this Gram-positive organism than was observed previously for a Gram-negative species.

Variations in the relative speeds of orofacial structures with stuttering severity.

Stuttering can be characterized in part as a disorder in the coordination of different muscle systems. In light of basic aspects of orofacial physiology and development, the speeds of the lips and tongue relative to the jaw may be an important dimension for evaluating motor coordination among persons who stutter (PWS). To test this idea, an electromagnetic system was used to obtain measures of lip, tongue, and jaw speed in 38 adults (29 PWS and 9 normally fluent speakers, NFS) as they repeated a simple speech utterance at a normal rate. Using categorical ratings of stuttering severity, ratios of tongue speed to jaw speed were significantly greater in PWS rated as severe, compared to NFS and other PWS. Significant increases in lower lip-to-jaw and tongue-to-jaw speed ratios with stuttering severity were also reflected in correlation analyses relating speed ratios to a continuous measure of stuttering severity. These trends in speed ratio were related to increases in lower lip and tongue speed and decreases in jaw speed with stuttering severity. Sources of the speed differences are discussed in relation to underlying muscle activity, motor compensation processes in adults, and the development of orofacial motor control in children who stutter.

A comparison of young stutterers' fluent versus stuttered utterances on measures of length and complexity.

This investigation attempted to clarify the relationship between stuttering in young children and the language factors of length and grammatical complexity. Sentences containing stutterings within the first few words, as produced by 12 stutterers (4-6 years old) in spontaneous conversational dyads, were analyzed for length and grammatical complexity. Results indicated that sentences in which an episode of stuttering occurred within the first three words were significantly longer and more complex than sentences that were free of perceptible stuttering and all other forms of fluency failure. Implications of these findings for the clinician are presented and discussed.

Speech naturalness ratings of treated stutterers.

This investigation compared the speech naturalness ratings of perceptually fluent speech samples produced by nonstutterers and stutterers who had been treated in six different therapy programs. The treated stutterers were then divided into two groups based on ease of identification using stutterer/nonstutterers judgments. The fluent speech of one group of stutterers was easily recognized as being produced by stutterers. The second group produced fluent speech that was difficult to distinguish from that used by normal talkers. Finally, pretreatment severity ratings (i.e., mild, moderate, and severe) were compared with posttreatment naturalness scores. Results indicated that a statistically significant difference existed between the naturalness ratings of the nonstutterers and the treated stutterers. Also, a significant difference was found between the naturalness ratings of the easy-to-identify stutterers. Finally, no difference was found in the posttreatment naturalness ratings of stutterers rated as mild, moderate, and severe before treatment.

Effects of segment and pause manipulations on the identification of treated stutterers.

This study examined the hypothesis that reading rate affects the identification of treated stutterers. Thirty-two pairs of recorded speech samples, in which one member of the pair was a treated stutterer and the other was a nonstutterer, were available from previous research. Listeners had been able to distinguish readily between the members of these pairs. For each pair of samples, the durations of the treated stutterer's segments and pauses were adjusted to match those of the nonstutterer as closely as possible by means of a computer-based waveform editor. A test tape was prepared that included the 32 original pairs of stimuli, the 32 edited pairs, and 64 pairs of foils. Listeners were required to indicate which member of each pair was the treated stutterer. Analysis of the responses indicated that the listeners' ability to distinguish between talkers was significantly reduced for the edited stimulus pairs. The results imply that the rate used by treated stutterers must be critically evaluated if the goal of therapy is the production of perceptually "normal" speech.

Temporal characteristics related to the discrimination of stutterers' and nonstutterers' speech samples.

Measurements of the difference in average speaking rate, average number of pauses, average pause duration, and average duration of the vowels that received primary stress were obtained from the speech samples of 35 stutterers and 35 nonstutterers. The samples had been screened to ensure that they contained no instances of overt stuttering, audible respirations, or inappropriate voicing. The measurements were used as the predictors in multiple linear regression analyses. The criterion variable was the average percent-correct discriminations of 40 subjects who listened to the samples in pairs and indicated which member of each pair was the stutterer. The results showed that the difference in speaking rate combined with either pause measure accounted for approximately 70% of the variance in the listeners' responses. The findings indicate that speaking rate and pauses are potential perceptual cues for listeners attempting to discriminate the speech of stutterers from that of nonstutterers.