Validation of an integrated pressure level measured earmold wideband real-ear-to-coupler difference measurement

OBJECTIVE

To validate measurement of predicted earmold wideband real-ear-to-coupler difference (wRECD) using an integrated pressure level (IPL) calibrated transducer and the incorporation of an acoustically measured tubing length correction.

DESIGN

Unilateral earmold SPL wRECD using varied hearing aid tubing length and the proposed predicted earmold IPL wRECD measurement procedure were completed on all participants and compared.

STUDY SAMPLE

22 normal hearing adults with normal middle ear status were recruited.

RESULTS

There were no clinically significant differences between probe-microphone and predicted earmold IPL wRECD measurements between 500 and 2500 Hz. Above 5000 Hz, the predicted earmold IPL wRECD exceeded earmold SPL wRECDs due to lack of standing wave interference. Test-retest reliability of IPL wRECD measurement exceeded the reliability of earmold SPL wRECD measurement across all assessed frequencies, with the greatest improvements in the high frequencies. The acoustically measured tubing length correction largely accounted for acoustic effects of the participant's earmold.

CONCLUSIONS

IPL-based measurements provide a promising alternative to probe-microphone earmold wRECD procedures. Predicted earmold IPL wRECD is measured without probe-microphone placement, agrees well with earmold SPL wRECDs and is expected to extend the valid bandwidth of wRECD measurement.

Validity and reliability of integrated pressure level real-ear-to-coupler difference measurements

OBJECTIVES

(1) To validate the measurement of foam-tip real-ear-to-coupler differences (wRECD) using an integrated pressure level (IPL) method and (2) to compare the reliability of this method to SPL-based measurement of the wRECD.

DESIGN

SPL-based wRECD and the proposed IPL wRECD measurement were completed bilaterally. Test-retest reliability of IPL wRECD was determined with full re-insertion into the ear canal and compared to published SPL wRECD test-retest data.

STUDY SAMPLE

22 adults with normal hearing and middle ear status were recruited.

RESULTS

Differences between SPL-based wRECD and IPL wRECD measurements were within 1.51 dB on average below 5000 Hz. At and above 5000 Hz, IPL wRECD exceeded SPL wRECDs by 6.11 dB on average. The average test-retest difference for IPL wRECD across all assessed frequencies was 0.75 dB with the greatest improvements in reliability found below 750 Hz and above 3000 Hz.

CONCLUSIONS

IPL wRECD yielded improved estimates compared to SPL wRECD in high frequencies, where standing-wave interference is present. Independence from standing wave interference resulted in increased wRECD values above 4000 Hz using the IPL measurement paradigm. IPL wRECD is more reliable than SPL wRECD, does not require precise probe-microphone placement, and provides a wider valid wRECD bandwidth than SPL-based measurement.

Predicting Hearing aid Benefit Using Speech-Evoked Envelope Following Responses in Children With Hearing Loss

Electroencephalography could serve as an objective tool to evaluate hearing aid benefit in infants who are developmentally unable to participate in hearing tests. We investigated whether speech-evoked envelope following responses (EFRs), a type of electroencephalography-based measure, could predict improved audibility with the use of a hearing aid in children with mild-to-severe permanent, mainly sensorineural, hearing loss. In 18 children, EFRs were elicited by six male-spoken band-limited phonemic stimuli--the first formants of /u/ and /i/, the second and higher formants of /u/ and /i/, and the fricatives /s/ and /∫/--presented together as /su∫i/. EFRs were recorded between the vertex and nape, when /su∫i/ was presented at 55, 65, and 75 dB SPL using insert earphones in unaided conditions and individually fit hearing aids in aided conditions. EFR amplitude and detectability improved with the use of a hearing aid, and the degree of improvement in EFR amplitude was dependent on the extent of change in behavioral thresholds between unaided and aided conditions. EFR detectability was primarily influenced by audibility; higher sensation level stimuli had an increased probability of detection. Overall EFR sensitivity in predicting audibility was significantly higher in aided (82.1%) than unaided conditions (66.5%) and did not vary as a function of stimulus or frequency. EFR specificity in ascertaining inaudibility was 90.8%. Aided improvement in EFR detectability was a significant predictor of hearing aid-facilitated change in speech discrimination accuracy. Results suggest that speech-evoked EFRs could be a useful objective tool in predicting hearing aid benefit in children with hearing loss.

Variability in the Estimated Amplitude of Vowel-Evoked Envelope Following Responses Caused by Assumed Neurophysiologic Processing Delays

Vowel-evoked envelope following responses (EFRs) reflect neural encoding of the fundamental frequency of voice (f0). Accurate analysis of EFRs elicited by natural vowels requires the use of methods like the Fourier analyzer (FA) to consider the production-related f0 changes. The FA's accuracy in estimating EFRs is, however, dependent on the assumed neurophysiological processing delay needed to time-align the f0 time course and the recorded electroencephalogram (EEG). For male-spoken vowels (f0 ~ 100 Hz), a constant 10-ms delay correction is often assumed. Since processing delays vary with stimulus and physiological factors, we quantified (i) the delay-related variability that would occur in EFR estimation, and (ii) the influence of stimulus frequency, non-f0 related neural activity, and the listener's age on such variability. EFRs were elicited by the low-frequency first formant, and mid-frequency second and higher formants of /u/, /a/, and /i/ in young adults and 6- to 17-year-old children. To time-align with the f0 time course, EEG was shifted by delays between 5 and 25 ms to encompass plausible response latencies. The delay-dependent range in EFR amplitude did not vary by stimulus frequency or age and was significantly smaller when interference from low-frequency activity was reduced. On average, the delay-dependent range was < 22% of the maximum variability in EFR amplitude that could be expected by noise. Results suggest that using a constant EEG delay correction in FA analysis does not substantially alter EFR amplitude estimation. In the present study, the lack of substantial variability was likely facilitated by using vowels with small f0 ranges.

Speech-Evoked Envelope Following Responses in Children and Adults

PURPOSE

Envelope following responses (EFRs) could be useful for objectively evaluating audibility of speech in children who are unable to participate in routine clinical tests. However, relative to adults, the characteristics of EFRs elicited by frequency-specific speech and their utility in predicting audibility in children are unknown.

METHOD

EFRs were elicited by the first (F1) and second and higher formants (F2+) of male-spoken vowels /u/ and /i/ and by fricatives /ʃ/ and /s/ in the token /suʃi/ presented at 15, 35, 55, 65, and 75 dB SPL. The F1, F2+, and fricatives were low-, mid-, and high-frequency dominant, respectively. EFRs were recorded between the vertex and the nape from twenty-three 6- to 17-year-old children and 21 young adults with normal hearing. Sensation levels of stimuli were estimated based on behavioral thresholds.

RESULTS

In children, amplitude decreased with age for /ʃ/-elicited EFRs but remained stable for low- and mid-frequency stimuli. As a group, EFR amplitude and phase coherence did not differ from that of adults. EFR sensitivity (proportion of audible stimuli detected) and specificity (proportion of inaudible stimuli not detected) did not vary between children and adults. Consistent with previous work, EFR sensitivity increased with stimulus frequency and level. The type of statistical indicator used for EFR detection did not influence accuracy in children.

CONCLUSIONS

Adultlike EFRs in 6- to 17-year-old typically developing children suggest mature envelope encoding for low- and mid-frequency stimuli. EFR sensitivity and specificity in children, when considering a wide range of stimulus levels and audibility, are ~77% and ~92%, respectively.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21136171.

Association Between Hospital-Acquired Harm Outcomes and Membership in a National Patient Safety Collaborative

IMPORTANCE

Hospital engagement networks supported by the US Centers for Medicare & Medicaid Services Partnership for Patients program have reported significant reductions in hospital-acquired harm, but methodological limitations and lack of peer review have led to persistent questions about the effectiveness of this approach.

OBJECTIVE

To evaluate associations between membership in Children's Hospitals' Solutions for Patient Safety (SPS), a federally funded hospital engagement network, and hospital-acquired harm using standardized definitions and secular trend adjustment.

DESIGN, SETTING, AND PARTICIPANTS

This prospective hospital cohort study included 99 children's hospitals. Using interrupted time series analyses with staggered intervention introduction, immediate and postimplementation changes in hospital-acquired harm rates were analyzed, with adjustment for preexisting secular trends. Outcomes were further evaluated by early-adopting (n = 73) and late-adopting (n = 26) cohorts.

EXPOSURES

Hospitals implemented harm prevention bundles, reported outcomes and bundle compliance using standard definitions to the network monthly, participated in learning events, and implemented a broad safety culture program. Hospitals received regular reports on their comparative performance.

MAIN OUTCOMES AND MEASURES

Outcomes for 8 hospital-acquired conditions were evaluated over 1 year before and 3 years after intervention.

RESULTS

In total, 99 hospitals met the inclusion criteria and were included in the analysis. A total of 73 were considered part of the early-adopting cohort (joined between 2012-2013) and 26 were considered part of the late-adopting cohort (joined between 2014-2016). A total of 42 hospitals were freestanding children's hospitals, and 57 were children's hospitals within hospital or health systems. The implementation of SPS was associated with an improvement in hospital-acquired condition rates in 3 of the 8 conditions after accounting for secular trends. Membership in the SPS was associated with an immediate reduction in central catheter-associated bloodstream infections (coefficient = -0.152; 95% CI, -0.213 to -0.019) and falls of moderate or greater severity (coefficient = -0.331; 95% CI, -0.594 to -0.069). The implementation of the SPS was associated with a reduction in the monthly rate of adverse drug events (coefficient = -0.021; 95% CI, -0.034 to -0.008) in the post-SPS period. The study team observed larger decreases for the early-adopting cohort compared with the late-adopting cohort.

CONCLUSIONS AND RELEVANCE

Through the application of rigorous methods (standard definitions and longitudinal time series analysis with adjustment for secular trends), this study provides a more thorough analysis of the association between the Partnership for Patients hospital engagement network model and reductions in hospital-acquired conditions. These findings strengthen previous claims of an association between this model and improvement. However, inconsistent observations across hospital-acquired conditions when adjusted for secular trends suggests that some caution regarding attributing all effects observed to this model is warranted.

The Influence of Male- and Female-Spoken Vowel Acoustics on Envelope-Following Responses

The influence of male and female vowel characteristics on the envelope-following responses (EFRs) is not well understood. This study explored the role of vowel characteristics on the EFR at the fundamental frequency (f0) in response to the vowel /ε/ (as in "head"). Vowel tokens were spoken by five males and five females and EFRs were measured in 25 young adults (21 females). An auditory model was used to estimate changes in auditory processing that might account for talker effects on EFR amplitude. There were several differences between male and female vowels in relation to the EFR. For male talkers, EFR amplitudes were correlated with the bandwidth and harmonic count of the first formant, and the amplitude of the trough below the second formant. For female talkers, EFR amplitudes were correlated with the range of f0 frequencies and the amplitude of the trough above the second formant. The model suggested that the f0 EFR reflects a wide distribution of energy in speech, with primary contributions from high-frequency harmonics mediated from cochlear regions basal to the peaks of the first and second formants, not from low-frequency harmonics with energy near f0. Vowels produced by female talkers tend to produce lower-amplitude EFR, likely because they depend on higher-frequency harmonics where speech sound levels tend to be lower. This work advances auditory electrophysiology by showing how the EFR evoked by speech relates to the acoustics of speech, for both male and female voices.

Detection and Management of Amyloid-Related Imaging Abnormalities in Patients with Alzheimer's Disease Treated with Anti-Amyloid Beta Therapy

Amyloid-related imaging abnormalities (ARIA) are adverse events reported in Alzheimer's disease trials of anti-amyloid beta (Aβ) therapies. This review summarizes the existing literature on ARIA, including bapineuzumab, gantenerumab, donanemab, lecanemab, and aducanumab studies, with regard to potential risk factors, detection, and management. The pathophysiology of ARIA is unclear, but it may be related to binding of antibodies to accumulated Aβ in both the cerebral parenchyma and vasculature, resulting in loss of vessel wall integrity and increased leakage into surrounding tissues. Radiographically, ARIA-E is identified as vasogenic edema in the brain parenchyma or sulcal effusions in the leptomeninges/sulci, while ARIA-H is hemosiderin deposits presenting as microhemorrhages or superficial siderosis. ARIA tends to be transient and asymptomatic in most cases, typically occurring early in the course of treatment, with the risk decreasing later in treatment. Limited data are available on continued dosing following radiographic findings of ARIA; hence, in the event of ARIA, treatment should be continued with caution and regular monitoring. Clinical trials have implemented management approaches such as temporary suspension of treatment until symptoms or radiographic signs of ARIA have resolved or permanent discontinuation of treatment. ARIA largely resolves without concomitant treatment, and there are no systematic data on potential treatments for ARIA. Given the availability of an anti-Aβ therapy, ARIA monitoring will now be implemented in routine clinical practice. The simple magnetic resonance imaging sequences used in clinical trials are likely sufficient for effective detection of cases. Increased awareness and education of ARIA among clinicians and radiologists is vital.

Developing Evidence for New Patient Safety Bundles Through Multihospital Collaboration

OBJECTIVE

Multihospital collaboration for safety improvements is increasingly common, but strategies for developing bundles when effective evidence-based practices are not well described are limited. The Children's Hospitals' Solutions for Patient Safety (SPS) Network sought to further reduce patient harm by developing improvement bundles when preliminary evidence was limited.

METHODS

As part of the novel Pioneer process, cohorts of volunteer SPS hospitals collaborated to identify a harm reduction bundle for carefully selected hospital-acquired harm categories where evidence-based practices were limited. For each harm type, a leadership team selected interventions (factors) for testing and guided the work throughout the Pioneer process. Using fundamental quality improvement techniques and a planned experimentation design, each participating hospital submitted outcome and process compliance data for the factor implemented. Data from all hospitals implementing that factor were analyzed together using Shewhart charts, response plots, and analysis of covariance to identify whether reliable implementation of the factor influenced outcomes. Factors were categorized based on strength of evidence and other clinical or evidentiary support. Factors with strong support were included in a final bundle and disseminated to all SPS hospitals.

RESULTS

The SPS began the bundle identification process for nine harm types and three have completed the process. The analytic approach resulted in four scenarios that along with clinical input guided the inclusion or rejection of the factor in the final bundle.

CONCLUSIONS

In this multihospital collaborative, quality improvement methods and planned experimentation were effective at developing evidence-based harm reduction bundles in situations where limited data for interventions exist.

The Accuracy of Envelope Following Responses in Predicting Speech Audibility

OBJECTIVES

The present study aimed to (1) evaluate the accuracy of envelope following responses (EFRs) in predicting speech audibility as a function of the statistical indicator used for objective response detection, stimulus phoneme, frequency, and level, and (2) quantify the minimum sensation level (SL; stimulus level above behavioral threshold) needed for detecting EFRs.

DESIGN

In 21 participants with normal hearing, EFRs were elicited by 8 band-limited phonemes in the male-spoken token /susa∫i/ (2.05 sec) presented between 20 and 65 dB SPL in 15 dB increments. Vowels in /susa∫i/ were modified to elicit two EFRs simultaneously by selectively lowering the fundamental frequency (f0) in the first formant (F1) region. The modified vowels elicited one EFR from the low-frequency F1 and another from the mid-frequency second and higher formants (F2+). Fricatives were amplitude-modulated at the average f0. EFRs were extracted from single-channel EEG recorded between the vertex (Cz) and the nape of the neck when /susa∫i/ was presented monaurally for 450 sweeps. The performance of the three statistical indicators, F-test, Hotelling's T, and phase coherence, was compared against behaviorally determined audibility (estimated SL, SL ≥0 dB = audible) using area under the receiver operating characteristics (AUROC) curve, sensitivity (the proportion of audible speech with a detectable EFR [true positive rate]), and specificity (the proportion of inaudible speech with an undetectable EFR [true negative rate]). The influence of stimulus phoneme, frequency, and level on the accuracy of EFRs in predicting speech audibility was assessed by comparing sensitivity, specificity, positive predictive value (PPV; the proportion of detected EFRs elicited by audible stimuli) and negative predictive value (NPV; the proportion of undetected EFRs elicited by inaudible stimuli). The minimum SL needed for detection was evaluated using a linear mixed-effects model with the predictor variables stimulus and EFR detection p value.

RESULTS

of the 3 statistical indicators were similar; however, at the type I error rate of 5%, the sensitivities of Hotelling's T (68.4%) and phase coherence (68.8%) were significantly higher than the F-test (59.5%). In contrast, the specificity of the F-test (97.3%) was significantly higher than the Hotelling's T (88.4%). When analyzed using Hotelling's T as a function of stimulus, fricatives offered higher sensitivity (88.6 to 90.6%) and NPV (57.9 to 76.0%) compared with most vowel stimuli (51.9 to 71.4% and 11.6 to 51.3%, respectively). When analyzed as a function of frequency band (F1, F2+, and fricatives aggregated as low-, mid- and high-frequencies, respectively), high-frequency stimuli offered the highest sensitivity (96.9%) and NPV (88.9%). When analyzed as a function of test level, sensitivity improved with increases in stimulus level (99.4% at 65 dB SPL). The minimum SL for EFR detection ranged between 13.4 and 21.7 dB for F1 stimuli, 7.8 to 12.2 dB for F2+ stimuli, and 2.3 to 3.9 dB for fricative stimuli.

CONCLUSIONS

EFR-based inference of speech audibility requires consideration of the statistical indicator used, phoneme, stimulus frequency, and stimulus level.

A maturity grid assessment tool for learning networks

BACKGROUND

The vision of learning healthcare systems (LHSs) is attractive as a more effective model for health care services, but achieving the vision is complex. There is limited literature describing the processes needed to construct such multicomponent systems or to assess development.

METHODS

We used the concept of a capability maturity matrix to describe the maturation of necessary infrastructure and processes to create learning networks (LNs), multisite collaborative LHSs that use an actor-oriented network organizational architecture. We developed a network maturity grid (NMG) assessment tool by incorporating information from literature review, content theory from existing networks, and expert opinion to establish domains and components. We refined the maturity grid in response to feedback from network leadership teams. We followed NMG scores over time for nine LNs and plotted scores for each domain component with respect to SD for one participating network. We sought subjective feedback on the experience of applying the NMG to individual networks.

RESULTS

LN leaders evaluated the scope, depth, and applicability of the NMG to their networks. Qualitative feedback from network leaders indicated that changes in NMG scores over time aligned with leaders' reports about growth in specific domains; changes in scores were consistent with network efforts to improve in various areas. Scores over time showed differences in maturation in the individual domains of each network. Scoring patterns, and SD for domain component scores, indicated consistency among LN leaders in some but not all aspects of network maturity. A case example from a participating network highlighted the value of the NMG in prompting strategic discussions about network development and demonstrated that the process of using the tool was itself valuable.

CONCLUSIONS

The capability maturity grid proposed here provides a framework to help those interested in creating Learning Health Networks plan and develop them over time.

Trends in Sexual Behavior Among Men Who have Sex with Men (MSM) in High-Income Countries, 1990-2013: A Systematic Review

HIV diagnoses among men who have sex with men (MSM) have been increasing in several high-income countries. A better understanding of the sexual behavior trends among MSM can be useful for informing HIV prevention. We conducted a systematic review of studies that examined behavioral trends (1990-2013) in any condomless anal sex, condomless anal sex with an HIV-discordant partner, and number of partners. Studies included come from the United States, Europe, and Australia. We found increasing trends in condomless anal sex and condomless anal sex with an HIV-discordant partner, and a decreasing trend in number of partners. The increase in condomless anal sex may help to explain the increase in HIV infections. More explanatory research is needed to provide insight into factors that contribute to these behavior trends. Continuous monitoring of HIV, risk behaviors, and use of prevention and treatment is needed to evaluate prevention efforts and monitor HIV transmission risk.

Localization-in-noise and binaural medial olivocochlear functioning in children and young adults

Children as young as 5 yr old localize sounds as accurately as adults in quiet in the frontal hemifield. However, children's ability to localize in noise and in the front/back (F/B) dimension are scantily studied. To address this, the first part of this study investigated localization-in-noise ability of children vs young adults in two maskers: broadband noise (BBN) and speech-babble (SB) at three signal-to-noise ratios: -12, -6, and 0 dB. In the second part, relationship between binaural medial olivocochlear system (MOC) function and localization-in-noise was investigated. In both studies, 21 children and 21 young adults participated. Results indicate, while children are able to differentiate sounds arriving in the F/B dimension on par with adults in quiet and in BBN, larger differences were found for SB. Accuracy of children's localization in noise (for both maskers) in the lateral plane was also poorer than adults'. Significant differences in binaural MOC interaction (mBIC; the difference between the sum of two monaural- and binaural-MOC strength) between adults and children were also found. For reasons which are not clear, adult F/B localization in BBN correlates better with mBIC while children's F/B localization in SB correlated better with binaural MOC strength.

Cochlear Delay and Medial Olivocochlear Functioning in Children with Suspected Auditory Processing Disorder

Behavioral manifestations of processing deficits associated with auditory processing disorder (APD) have been well documented. However, little is known about their anatomical underpinnings, especially cochlear processing. Cochlear delays, a proxy for cochlear tuning, measured using stimulus frequency otoacoustic emission (SFOAE) group delay, and the influence of the medial olivocochlear (MOC) system activation at the auditory periphery was studied in 23 children suspected with APD (sAPD) and 22 typically developing (TD) children. Results suggest that children suspected with APD have longer SFOAE group delays (possibly due to sharper cochlear tuning) and reduced MOC function compared to TD children. Other differences between the groups include correlation between MOC function and SFOAE delay in quiet in the TD group, and lack thereof in the sAPD group. MOC-mediated changes in SFOAE delay were in opposite directions between groups: increase in delay in TD vs. reduction in delay in the sAPD group. Longer SFOAE group delays in the sAPD group may lead to longer cochlear filter ringing, and potential increase in forward masking. These results indicate differences in cochlear and MOC function between sAPD and TD groups. Further studies are warranted to explore the possibility of cochlea as a potential site for processing deficits in APD.

Managing identity impacts associated with disclosure of HIV status: a qualitative investigation

Disclosure of HIV status to potential and current sex partners by HIV-positive people (HIVPP) is a complex issue that has received a significant amount of attention. Research has found that disclosure depends upon the evaluation by HIVPP of potential benefits and risks, especially of the risks stemming from the profound social stigma of HIV and AIDS. Drawing on concepts from Goffman's classic stigma theory and Anderson's more recently developed cultural-identity theory of drug abuse, we analyzed data from in-depth, post-intervention qualitative interviews with 116 heterosexually active, HIV-positive injection drug users enrolled in a randomized trial of a behavioral intervention to prevent HIV transmission. We explored how disclosure experiences lead to "identity impacts" defined as: (1) identity challenges (i.e. interactions that challenge an individual's self-concept as a "normal" or non-deviant individual); and (2) identity transformations (i.e. processes whereby an individual comes to embrace a new identity and reject behaviors and values of an old one, resulting in the conscious adoption of a social and/or public identity as an HIV-positive individual). Participants engaged in several strategies to manage the identity impacts associated with disclosure. Implications of these findings for research and prevention programming are discussed.

Blacks' and whites' attitudes toward race and nativity concordance with doctors

While research shows that race is an important factor in patient-doctor interaction, very little is known about patients' attitudes toward doctors' race or nativity. This paper examines 2 specific components of these attitudes. We found that 16% of a Cincinnati, Ohio, sample believed that same-race doctors better understand their health problems, and 22% expected to be more at ease with same-race doctors. Blacks were more likely than whites to hold this belief and expectation, with the largest racial difference among those with college degrees. Looking at nativity, nearly one-third of the respondents believed that US-born doctors better understand their health problems and expected to be more at ease with US-born doctors. Again, blacks were more likely than whites to report a more positive view of US-born doctors compared to foreign-born doctors, with the effect of race varying by education. Future research should further explicate the nature of these attitudes and assess how these attitudes affect health care interactions.

Weighting of Auditory Feedback Across the English Vowel Space

Auditory feedback in the headphones of talkers was manipulated in the F1 dimension using a real-time vowel formant filtering system. Minimum formant shifts required to elicit a response and the amount of compensation were measured for vowels across the English vowel space. The largest response in production of F1 was observed for the vowel /ε/ and smaller or non-significant changes were found for point vowels. In general, changes in production were of a compensatory nature that reduced the error in the auditory feedback.

Individual, interpersonal, and structural correlates of effective HAART use among urban active injection drug users

Among individuals receiving highly active antiretroviral therapy (HAART), injection drug users (IDUs) are less likely to achieve HIV suppression. The present study examined individual-level, interpersonal, and structural factors associated with achieving undetectable plasma viral load (UVL) among US IDUs receiving recommended HAART. Data were from baseline assessments of the INSPIRE (Interventions for Seropositive Injectors-Research and Evaluation) study, a 4-site, secondary HIV prevention intervention for heterosexually active IDUs. Of 1113 study participants at baseline, 42% (n = 466) were currently taking recommended HAART (34% were female, 69% non-Hispanic black, 26% recently homeless; median age was 43 years), of whom 132 (28%) had a UVL. Logistic regression revealed that among those on recommended HAART, adjusted odds of UVL were at least 3 times higher among those with high social support, stable housing, and CD4 > 200; UVL was approximately 60% higher among those reporting better patient-provider communication. Outpatient drug treatment and non-Hispanic black race and an interaction between current drug use and social support were marginally negatively significant. Among those with high perceived support, noncurrent drug users compared with current drug users had a greater likelihood of UVL; current drug use was not associated with UVL among those with low support. Depressive symptoms (Brief Symptom Inventory) were not significant. Results suggest the major role of social support in facilitating effective HAART use in this population and suggest that active drug use may interfere with HAART use by adversely affecting social support. Interventions promoting social support functioning, patient-provider communication, stable housing, and drug abuse treatment may facilitate effective HAART use in this vulnerable population.

Race, socioeconomic status, and the perceived importance of positive self-presentation in health care

Hundreds of studies have documented disparities in medical treatment in the USA. These findings have generated research and initiatives intended to understand and ameliorate such disparities. Many articles examine disadvantaged patients' beliefs and attitudes toward health care, but generally limit their investigation to how these beliefs and attitudes influence adherence and utilization. Thus, this approach fails to consider whether patients use particular strategies to overcome providers' potentially negative perceptions of them and/or obtain quality medical care. In this paper, we examine positive self-presentation as a strategy that may be used by disadvantaged groups to improve their medical treatment. Analysis of survey data (the 2004 Greater Cincinnati Survey) suggests that both African Americans and lower socioeconomic status persons are more likely than whites or higher socioeconomic status persons to report that positive self-presentation is important for their getting the best medical care. Based on these findings, we suggest several routes for future research that will advance our understanding of patients' everyday strategies for getting the best health care.

Recording Human Evoked Potentials That Follow the Pitch Contour of a Natural Vowel

We investigated whether pitch-synchronous neural activity could be recorded in humans, with a natural vowel and a vowel in which the fundamental frequency was suppressed. Small variations of speech periodicity were detected in the evoked responses using a fine structure spectrograph (FSS). A significant response (P < 0.001) was measured in all seven normal subjects even when the fundamental frequency was suppressed, and it very accurately tracked the acoustic pitch contour (normalized mean absolute error < 0.57%). Small variations in speech periodicity, which humans can detect, are therefore available to the perceptual system as pitch-synchronous neural firing. These findings suggest that the measurement of pitch-evoked responses may be a viable tool for objective speech audiometry.

Sexual risk taking among HIV-positive injection drug users: contexts, characteristics, and implications for prevention

HIV-positive injection drug users (IDUs) ( N = 161) were recruited to complete a qualitative interview and a quantitative survey about sexual behavior and transmission risk. We identified two contexts in which exposure encounters occurred most commonly for HIV-positive IDUs: in intimate serodiscordant relationships and in the drug/sex economy. Salient characteristics in both contexts included the role of intimacy, drug use and sexual decision making, disclosure of HIV status, and perceived responsibility. Although these characteristics emerged in both risk contexts, they operated differently within each context. The preservation of intimacy was paramount among those in serodiscordant relationships, and agreements to take risks were common. In the drug/sex economy, serostatus disclosure was uncommon and drug acquisition and use played a significant role in sexual risk taking. Our data emphasize a need to address the specific transmission risk contexts occurring among HIV-positive IDUs and to prioritize social and interpersonal factors when promoting safer sexual norms among HIV-positive IDUs.

The Life Priorities of HIV-Seropositive Injection Drug Users: Findings from a Community-Based Sample

Using cross-sectional data from an ethnically diverse sample of 161 HIV-seropositive injection drug users (IDUs), we investigated (1) how HIV-positive IDUs rank their life priorities, (2) whether HIV prioritization (defined as whether or not ranking HIV as a top priority) is associated with risk behaviors, and (3) potential correlates of HIV prioritization. HIV was ranked as the most important priority by 37% of the participants. Among those who did not rank HIV as the top priority, housing, money, and safety from violence were particularly salient priorities. Those who gave the highest priority to HIV were less likely to have unprotected vaginal sex with primary partners who were HIV negative or of unknown serostatus, were less likely to split drugs with a used syringe, and used fewer numbers of injection drugs. HIV prioritization, however, was not associated with sex risk behaviors with nonprimary partners and HIV-positive primary partners. Significant correlates of HIV prioritization included age and the use of a heroin/stimulant mixture. These findings provide a number of important implications for HIV prevention intervention research for HIV-positive IDUs.

Human auditory steady-state responses

Steady-state evoked potentials can be recorded from the human scalp in response to auditory stimuli presented at rates between 1 and 200 Hz or by periodic modulations of the amplitude and/or frequency of a continuous tone. Responses can be objectively detected using frequency-based analyses. In waking subjects, the responses are particularly prominent at rates near 40 Hz. Responses evoked by more rapidly presented stimuli are less affected by changes in arousal and can be evoked by multiple simultaneous stimuli without significant loss of amplitude. Response amplitude increases as the depth of modulation or the intensity increases. The phase delay of the response increases as the intensity or the carrier frequency decreases. Auditory steady-state responses are generated throughout the auditory nervous system, with cortical regions contributing more than brainstem generators to responses at lower modulation frequencies. These responses are useful for objectively evaluating auditory thresholds, assessing suprathreshold hearing, and monitoring the state of arousal during anesthesia.

Childhood sexual abuse and sexual transmission risk behaviour among HIV-positive men who have sex with men

Previous studies have indicated an association between childhood sexual abuse (CSA) and adult sexual risk behaviour among women and among men who have sex with men (MSM). However, no studies to date have tested the hypothesis that a history of CSA predicts sexual behaviour carrying risk of transmission of HIV to others, i.e. in a known HIV-positive cohort. The present study tested this hypothesis among a sample of 456 HIV-positive MSM recruited from community venues in New York and San Francisco. CSA history was found to be significantly associated with past (in the last 90 days) unprotected anal sex acts, both insertive (33% versus 20%, p < 0.05) and receptive (43% versus 27%, p < 0.02), with partners of HIV-negative or unknown serostatus. Further, several potential mediators of this effect were tested, and three found to be predicted by CSA history. Each of these potential mediators was associated with sexual risk behaviour, but differentially: anxiety and hostility were significantly associated with insertive acts, while anxiety, hostility and suicidality were associated with receptive acts. Mediation analyses supported the hypothesis that these factors significantly (albeit partially) accounted for the association of CSA with receptive anal intercourse. Nonsignificant mediation effects were found for insertive sex, suggesting the operation of unmeasured mediating variables. These results highlight the importance of mental health services for individuals who have been sexually abused, both for personal and for public health benefit, and also indicate a need for further research into mediators of CSA effects on transmission-related behaviour.

nef-deleted HIV-1 inhibits phagocytosis by monocyte-derived macrophages in vitro but not by peripheral blood monocytes in vivo

OBJECTIVE

HIV-1 infection impairs a number of macrophage effector functions, but the mechanism is unknown. We studied the role of HIV-1 Nef in modulating phagocytosis by human monocytes and monocyte-derived macrophages (MDM).

DESIGN AND METHODS

Using a flow cytometric assay, phagocytosis of Mycobacterium avium complex (MAC) by monocytes in whole blood of Sydney Blood Bank Cohort (SBBC) members infected with a nef-deleted (Delta nef) strain of HIV-1 was compared with that of monocytes from uninfected or wild-type (WT) HIV-infected subjects. The specific impact of Nef on phagocytosis by MDM was determined by either infecting cells in vitro with Delta nef strains of HIV-1 or electroporating Nef into uninfected MDM.

RESULTS

MAC phagocytic capacity of monocytes from SBBC members was equivalent to that of cells from uninfected individuals (P = 0.81); it was greater than that of cells from individuals infected with WT HIV-1 (P < 0.0001), irrespective of CD4 counts and HIV viral load. In contrast, in vitro infection of MDM with either Delta nef or WT strains of HIV-1 resulted in similar levels of HIV replication and equivalent impairment of phagocytosis via Fc gamma and complement receptors. Electroporation of Nef into MDM did not alter phagocytic capacity.

CONCLUSIONS

This study provides evidence demonstrating the complex indirect effect of Nef on phagocytosis by peripheral blood monocytes (infrequently infected with HIV-1) in vivo. Conversely, the fact that MDM infected with either Delta nef or WT HIV-1 in vitro (high multiplicity of infection) show comparably impaired phagocytosis, indicates that HIV-1 infection of macrophages can directly impair function, independent of Nef.

Objective calibration of bone conductors using otoacoustic emissions

OBJECTIVE

To demonstrate a technique for objectively calibrating bone conductors on an individual basis using distortion product otoacoustic emissions (DPOAEs).

DESIGN

Individual calibrations were obtained using DPOAEs recorded from a single ear of 21 normally hearing adults. Validity and robustness of the technique were investigated through subjective phase cancellation measurements and sensitivity analysis.

RESULTS

Calibrations obtained using the DPOAE method were well supported by phase cancellation results. Intersession repeatability was good, and manipulation of the DPOAE data showed that the calculated calibration is relatively insensitive to small variations of emission magnitude. Bilateral stimulation through bone conduction did not display an apparent effect on emission magnitude in a single individual.

CONCLUSION

Bone conductors can be accurately calibrated on an individual basis with good repeatability using DPOAEs. The technique is robust and offers an objective, noninvasive calibration method for research and specialized clinical applications. No training and only passive cooperation are required, making the procedure ideal for special groups such as children. A number of limitations will reduce the clinical utility of this technique. Important audiometric frequencies below 1 kHz cannot be tested because of noise, because individuals with significant hearing loss are unlikely to produce sufficient DPOAEs, and because commercial bone conductors typically have poor high-frequency response above 4 kHz.

Suicide among the elderly in Honolulu County: a multiethnic comparative study (1987-1992)

Suicide rates for the elderly continue to be the highest for any age group. Although these rates are known to be significant, little study has been given to the ethnic variability associated with this phenomenon. This retrospective study was undertaken to explore this issue and involved a review of the coroner's reports for completed elder suicides (65 years of age or older) for Honolulu County from 1987 through 1992 inclusive. The results showed a mean age of 75 years, with the highest incidence of completion in the 80+ age group. The predominant method of suicide completion in this study group was found to be hanging, followed by jumping, firearms, and poisoning. There were significant gender and ethnic differences in the method of suicide completion. Almost half of the sample saw a healthcare provider within the 6 months before their death. Comparisons with other elder suicide studies are presented.

Distortion product otoacoustic emissions stimulated through bone conduction

OBJECTIVE

To demonstrate the viability of bone conduction as a novel method for stimulation of distortion product otoacoustic emissions (DPOAEs).

DESIGN

DPOAEs were recorded from a single ear of 23 normally hearing adults using bone and air conduction for the delivery of stimulus tones. Exploration of the input-output function was performed by varying stimulus frequency and magnitude.

RESULTS

Bone-stimulated emissions demonstrated similar characteristics to those obtained through standard air transmission techniques. Characteristic nonlinear DPOAE growth was found as the magnitude of the higher frequency stimulus tone, L2, was increased monotonically with other parameters fixed. Bilateral stimulation due to using bone conduction did not saturate the mechanisms of emission suppression. Emission magnitude was not altered substantially by occlusion of the ear canal.

CONCLUSION

Bone conduction can be used successfully to elicit DPOAEs. Absolute comparison of air- and bone-stimulated DPOAEs was difficult because of imprecise calibration of the bone conductors for each individual and particular placement. Properties unique to bone conduction, such as simultaneous bilateral stimulation and reduction of stimulus magnitude in the ear canal, may make bone conduction attractive for clinical measurement of DPOAEs.

Restricted HIV-1 infection of human astrocytes: potential role of nef in the regulation of virus replication

A small percentage of astrocytes are consistently infected in vivo by HIV-1 and may contribute to neuropathogenesis despite a non-productive infection. Overexpression of the nef gene product has been associated with their infection both in vivo and in vitro. We examined the role of the nef gene during HIV replication in astrocytes (U251MG cells) following transfection with pNL4-3 proviral plasmid or isogenic strains containing a deletion or point mutation in the nef gene (pNL4-3deltaNef; pNL4-3-nef-stop). We were able to initiate virus replication which peaked at 5 days post-transfection and became non-productive after 21 days. Nef protein expression by wild type pNL4-3 was observed at low levels compared to control HeLa cells at peak virus replication. At later time points after development of a non-productive infection, viral antigen and Nef protein was not detectable however virus was readily recovered by co-culture with CD4+T-cells. Interestingly, virus production was significantly enhanced by a 222 base pair deletion in the nef reading frame. This was not observed with a frame shifting point mutation in nef, indicating a suppressive effect of nef on virus production in astrocytes. The enhanced virus production from nef-deleted pNL4-3 in U251MG cells was not reversed by co-expression of Nef from a second Nef-expressing plasmid, and in fact Nef expression in trans had a further positive effect on virus production. This suggested opposing effects of the Nef protein and elements contained within the nef sequence on virus production in astrocytes. Despite the low expression of Nef by U251MG astrocytes, relatively high amounts of multiply spliced 2 kb mRNA were present compared to HeLa cells. These data demonstrate that an acute low-level infection of astrocytes rapidly becomes a non-productive infection and this process is assisted by sequences in nef. The low level Nef protein expression, despite high levels of mRNA, suggests a block in translation of multiply spliced HIV mRNA in astrocytes, or a translational control mechanism not yet characterised.

Myopathy and spontaneous Pasteurella pneumotropica-induced abscess formation in an HIV-1 transgenic mouse model

In an effort to augment human immunodeficiency virus type 1 (HIV-1) gene expression in transgenic mice, an infectious proviral DNA clone was modified by deleting the two NF kappa B binding sites and some adjacent upstream LTR sequences and replacing them with the core enhancer of Moloney murine leukemia virus (MLV). Two independent lines of MLV/HIV transgenic mice were established that expressed HIV-1-specific RNA in lymphoid tissue, striated skeletal muscle, and the eye lens. Heterozygous animals from each transgenic line spontaneously developed an inflammatory disease of the eye associated with the production of copious amounts of purulent lacrimal secretions beginning at 2 weeks of age. Periorbital abscess formation became grossly apparent by 2 months of age and Pasteurella pneumotropica was cultured from the harderian glands and conjunctival surfaces of many of the MLV/HIV animals but not their nontransgenic, cohabiting littermates. This gram-negative commensal bacterium has been previously associated with a similar disease phenotype in immunocompromised (e.g., nude mice) rodent colonies. MLV/HIV mice developed normally until 15 weeks of age, when weight loss and wasting occurred, culminating in premature death (as earlier as 6 months of age). The cachexia was associated with an initially focal and subsequently progressive myopathy, coinciding with age-related increases of HIV gene expression in muscle.

Effect of poultry waste feeding on intake, body weight and milk yield of Holstein cows

Forty lactating Holstein cows were fed 0, 5.9, 11.7, or 17.4% processed poultry excreta in total mixed rations. The effect of treatment was evaluated on feed intake, BW, milk yield, and composition. Processes poultry excreta appeared to be well accepted by cows even when included in rations at 17.4% of total DM. Mean DM intake averaged 19.3, 19.7, 19.5, and 19.7 kg/d for cows fed 0, 5.9, 11.7, and 17.4% processed poultry excreta, respectively. Body weight change averaged 2.0, 1.7, -1.7, and 1.4 kg/wk from 90 to 180 d of lactation for cows fed from 0 to 17.4% processed poultry excreta, respectively. Fat-corrected milk (4%) yield was similar among treatment groups, averaging 24.2, 26.1, 24.6, and 25.1 kg/d for cows fed 0, 5.9, 11.7, and 17.4% processed poultry excreta. No differences were found for milk and fat yields of percentage fat among treatment means. No off flavors in milk could be attributed to processed poultry excreta added to feed. Processed poultry excreta fed up to 17.4% of total mixed rations supported both adequate feed intake and high milk yields of mid-lactation cows.

Routine intraoperative angioscopy in lower extremity revascularization

The inability to see through blood remains the main obstacle to the widespread and routine use of angioscopy. Local irrigation with a balanced salt solution is presently the most widely used method to clear the blood. By applying basic principles of irrigation and using a unique, dedicated, irrigation pump, we found that routine angioscopy during lower extremity revascularization that yields consistent high-quality studies is feasible, clinically useful, and safe. Between May 1, 1987, and July 31, 1988, 136 intraoperative angioscopies were performed during 112 peripheral bypass procedures, 15 thrombectomies, 2 embolectomies, and 7 miscellaneous revascularization procedures. Mean total irrigation fluid used in the peripheral bypasses was 398 mL (range, 0 to 1400 mL). Good visual quality was obtained in more than 80% of angioscopies and the failure rate was only 1.8%. On the basis of the findings in 71 of the 136 angioscopies, 78 clinical or surgical decisions were made. No complications were directly attributable to the insertion of the angioscope or use of the pump.