Clinical Outcomes and Healthcare Resource Utilization for Patients With Lower-Risk Myelodysplastic Syndromes Treated With Erythropoiesis-Stimulating Agents.

INTRODUCTION: Real-world studies of lower-risk myelodysplastic syndromes (LR-MDS) are limited. We evaluated treatment patterns, clinical outcomes, and healthcare resource utilization (HCRU) among patients with LR-MDS treated with erythropoiesis-stimulating agents (ESAs) in the United States. PATIENTS AND METHODS: This retrospective study included patients with LR-MDS who initiated treatment with ESAs between January 1, 2016 and June 30, 2019. The primary analysis assessed patient demographic and clinical characteristics, treatment patterns, clinical outcomes (hematologic response, transfusion requirements, disease progression), and HCRU (medical encounters, laboratory tests, and medication use). Subgroup analyses of patients repeatedly treated with ESA therapy evaluated selected clinical outcomes and primary ESA failure by SF3B1 mutational status, per recently updated NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines©). RESULTS: A total of 142 patients were included with a median follow-up time of 17 months (interquartile range [IQR], 7-33). Median age at ESA initiation was 79 years (IQR, 73-85). Patients were predominantly male (54%), overweight or obese (32% and 23%, respectively), of White race (96%) and non-Hispanic ethnicity (89%). Overall, 57% patients were initially treated with darbepoetin alfa and 43% with epoetin alfa. Clinical outcomes were poor, and there was a significant burden on both the health system and individual patients treated with ESA therapies. Hematologic improvement- erythroid was only seen in 26% of 142 patients treated with ESAs, and 65% of 82 retreated patients experienced primary ESA failure. CONCLUSION: Our results indicate that primary ESA failure is largely unrecognized and that many patients should be considered for alternative treatments.

Oral Steroid Responsive Allergic Eruption Following COVID-19 Vaccination.

Cutaneous reactions following immunization, while rare, are a known adverse effect of many vaccinations. The precise etiology of such dermatologic manifestations and their long-term effects are largely unknown. This case study describes a 37-year-old female patient who initially presented with an edematous, pruritic facial rash that developed one day after vaccination against COVID-19, progressively worsened, and proved resistant to various forms of treatment. Following extensive workup, patch testing revealed a previously non-existent allergy to gold sodium thiosulfate. The use of metals, such as gold, in vaccine manufacturing and biotechnology may suggest the possibility of a relationship between injections and immunologic sensitization. Patch testing may be a useful adjunct in evaluating persistent cutaneous reactions following vaccination.

Tackling of Immunorefractory Tumors by Targeting Alternative Immune Checkpoints.

Physiologically, well known or traditional immune checkpoints (ICs), such as CTLA-4 and PD-1, are in place to promote tolerance to self-antigens and prevent generation of autoimmunity. In cancer, the ICs are effectively engaged by the tumor cells or stromal ells from the tumor microenvironment through expression of cognate ligands for the ICs present on the cell surface of CD8+ T lymphocytes. The ligation of ICs on CD8+ T lymphocytes triggers inhibitory signaling pathways, leading to quiescence or an exhaustion of CD8+ T lymphocytes. This results in failure of immunotherapy. To overcome this, several FDA-approved therapeutic antibodies are available, but the clinical outcome is quite variable due to the resistance encountered through upregulated expression of alternate ICs such as VISTA, LAG-3, TIGIT and TIM-3. This review focuses on the roles played by the traditional as well as alternate ICs and the contribution of associated signaling pathways in generating such resistance to immunotherapy. Combinatorial targeting of traditional and alternate ICs might be beneficial for immune-refractory tumors.

Outcome of cranial cruciate ligament replacement with an enhanced polyethylene terephthalate implant in the dog: A pilot clinical trial.

OBJECTIVE: To assess the 6-month outcome and survival of enhanced polyethylene terephthalate (PET) implants as a replacement for the cranial cruciate ligament (CCL) in dogs with spontaneous CCL disease (CCLD). STUDY DESIGN: Pilot, prospective case series. ANIMALS: Ten client-owned large breed dogs with unilateral spontaneous CCLD. METHODS: Dogs were evaluated before and 6 months after intra-articular placement of a PET implant with the Liverpool Osteoarthritis in Dogs questionnaire and force platform gait analysis. Arthroscopy was performed 6 months after surgery to visually assess implant integrity. RESULTS: Scores on owner questionnaires and limb asymmetry improved in all dogs that reached the 6-month time point, by 51.7% (p = .008) and 86% (p = .002), respectively. The PET implant appeared intact and functioning in two stifles, partially intact and functioning in four stifles and completely torn in three stifles. One dog had an implant infection and was removed from the study. Evidence of deterioration and tearing occurred in the midbody of the implant. CONCLUSION: Although function improved over the course of this study, only 2/10 implants appeared intact 6 months after placement. CLINICAL SIGNIFICANCE: Implant survivability prohibits further clinical investigation using this implant.

Gender, bottom-line mentality, and workplace mistreatment: The roles of gender norm violation and team gender composition.

Although gender has been identified as an important antecedent in workplace mistreatment research, empirical research has shown mixed results. Drawing on role congruity theory, we propose an interactive effect of gender and bottom-line mentality on being the target of mistreatment. Across two field studies, our results showed that whereas women experienced more mistreatment when they had higher levels of bottom-line mentality, men experienced more mistreatment when they had lower levels of bottom-line mentality. In another field study, using round-robin survey data, we found that team gender composition influenced the degree to which the adoption of a bottom-line mentality by female team members was perceived to be a gender norm violation, which subsequently predicted their likelihood of being mistreated. Specifically, women who had higher (vs. lower) levels of bottom-line mentality were more likely to be perceived to violate gender norms in teams with a lower proportion of women, and in turn, perceived gender norm violation was positively associated with being mistreated. We discuss theoretical and practical implications of our findings and directions for future research. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Determination of the center of mass in a heterogeneous population of dogs.

The center of mass (CoM) is the location in a body where mass distribution is balanced. It has a fundamental role in balance and motion which has been poorly described in the dog. The objective of this study was to estimate the variance of the center of mass (CoM) in a heterogeneous population of client-owned dogs and to describe the relationship between CoM, subject morphometrics and an inertial measurement unit (IMU) box positioned ventrally on a neck collar. A single force platform and a reaction board were used to determine CoM in the transverse, sagittal and dorsal planes in thirty-one healthy adult dogs. A series of morphometric measurements were acquired with each dog standing, including distances relative to an IMU box positioned ventrally on a neck collar. Mean transverse plane CoM was 48% the distance from ischium to the IMU box, near the xiphoid process. Mean sagittal place CoM was 59% the width of the chest on the left side. Mean dorsal plane CoM was 41% the distance from the most dorsal to the most ventral aspect of the body. Dog length was the primary variable required to maximize the relationship between three-dimensional CoM and identifiable variables measured. A CoM based normalization procedure should be considered to normalize mass or motion based outcome measure output (e.g., ground reaction forces, vector acceleration) in a heterogeneous population of dogs. Future research will be needed to determine if CoM-based normalization procedures reduce variance in outcome measures affected by subject morphometrics.

Gastrointestinal Intramural Pancreatic Pseudocysts in a Dog: A Case Report and Human Literature Review.

A 9.5 yr old Yorkshire terrier presented with chronic intermittent vomiting and lethargy of 1.5 yr duration that progressed to generalized weakness. Insulin:glucose ratio was consistent with an insulinoma. Triple-phase computed tomography revealed a mid-body pancreatic nodule. The mid-body pancreatic nodule was enucleated; histopathology was consistent with an insulinoma. Two weeks after the operation, the dog presented for anorexia and diarrhea. Abdominal ultrasound revealed a thick-walled cystic lesion along the dorsal stomach wall. An intramural gastric pseudocyst was diagnosed via exploratory laparotomy and intraoperative gastroscopy. Comparison of amylase and lipase levels of the cystic fluid with that of concurrent blood serum samples confirmed the lesion was of pancreatic pseudocyst origin. The gastric pseudocyst was omentalized. Two weeks after the operation, the dog re-presented for anorexia, regurgitation, and diarrhea. An intramural duodenal pseudocyst was identified and treated with a duodenal resection and anastomosis. The dog has remained asymptomatic and recurrence free based on serial abdominal ultrasounds 22 mo following insulinoma removal. To our knowledge, this phenomenon of pancreatic pseudocysts forming in organs other than the pancreas has not been reported in dogs. This case report and comprehensive human literature review purpose is to raise awareness of this disease process in dogs.

Sustenance for Success: Connections between Community College Students and Food Insecurity.

To assess the connections between student success and food insecurity of community college students the authors present the results of three studies conducted between fall 2017 and spring 2020. Using a cross-sectional design and the intercept method, 858 participants completed the Household Food Security Survey Module. The three hypotheses for the studies were: there is a relationship between food insecurity and (a) GPA, (b) concentration, and (c) energy levels. Food insecurity levels for the participants varied-Monroe, 99%; Spaid and Gillett-Karam, 52%; and Liburd, 30%. Liburd found a significant relationship for all three hypotheses. Monroe's 2020 findings that 99% of her sample was food insecure presents challenges for addressing unmet needs for African American/Black students. Spaid and Gillett-Karam's 2018 findings showed that minority women with Pell Grants had food insecurity levels three times higher than other groups. Traditional student support services should include supplemental services for food-insecure student populations.

Cochlear Mechanisms and Otoacoustic Emission Test Performance.

OBJECTIVES: This study aims to determine the impact of controlling cochlear-source mechanism on the accuracy with which auditory status is identified using otoacoustic emissions (OAEs) in two groups of subjects with normal hearing (NH) and subjects with mild to moderate hearing loss. DESIGN: Data were collected from 212 subjects with NH and with mild to moderate hearing loss who fell into two categories based on a distortion product OAE (DPOAE) screening protocol: the uncertain-identification group (where errors were likely) and the certain-identification group (where errors were unlikely). DPOAE fine-structure patterns were recorded at intervals surrounding f2 = 1, 2 and 4 kHz (f2/f1 ratio = 1.22), with L2 = 35, 45, and 55 dB SPL (L1/L2 ratio = 10 dB). The discrete cosine transform was used to smooth fine structure, limiting the source contribution to the distortion source only. Reflection-source OAEs were also recorded using amplitude-modulated stimulus frequency OAEs (AM-SFOAE). Area under the relative operating characteristic (AROC) curve was used to quantify test accuracy when the source contribution was controlled versus the condition where both sources contribute. Additionally, failure rate, fixed at 5% for NH ears, as a function of behavioral-threshold category was evaluated. RESULTS: When data for the entire subject group were examined, reducing the reflection-source contribution to the DPOAE did not result in better test performance than the best control condition at any frequency tested. When the subjects with NH were restricted to those with confirmed fine structure, AROC analyses indicated that reducing the reflection-source contribution resulted in several small increases in the accuracy (2%-5%) with which auditory status was identified relative to the best control condition. This improvement was observed for the lowest stimulus levels (i.e., L2 = 35 or 45 dB SPL). In this subset of subjects, distortion-source DPOAEs resulted in more accurate identification of mild hearing loss for a fixed false-positive rate of 5% in NH ears at lower L2's, conditions with poor accuracy in the larger group of subjects. The impact of controlling the source contribution on the identification of moderate losses was less clear in the reduced subject group, with some conditions where the distortion-source DPOAE was more accurate than the control condition and other conditions where there was no change. There was no evidence that reflection-source AM-SFOAEs more accurately identified ears with hearing loss when compared to any of the DPOAE conditions in either the large or reduced group of subjects. CONCLUSION: While improvements in test accuracy were observed for some subjects and some conditions (e.g., mild hearing losses and low stimulus levels in the reduced subset of subjects), these results suggest that restricting cochlear source contribution by "smoothing" DPOAE fine structure is not expected to improve DPOAE test accuracy in a general population of subjects. Likewise, recording reflection-source OAEs using the AM-SFOAE technique would not be expected to more accurately identify hearing status compared to mixed- or single-source DPOAEs.

Articular cartilage lesions associated with complete lateral meniscal tears in the dog.

OBJECTIVE: To describe articular cartilage (AC) lesions associated with complete lateral meniscal tears in dogs. STUDY DESIGN: Observational series. ANIMALS: Seventeen dogs with arthroscopic evidence of a complete lateral meniscal tear and associated AC lesions. METHODS: Medical records of dogs with arthroscopic evidence of complete lateral meniscal tear and associated AC lesions between March 2006 and December 2017 were examined for arthroscopic findings. RESULTS: The cranial cruciate ligament (CrCL) was intact in 11 of 17 dogs, partially ruptured but competent in 4 of 17 dogs, and completely ruptured in 2 of 17 dogs. All dogs had grossly normal caudal cruciate ligament, medial meniscus, and AC of the medial compartment. In each dog, a complete radial tear of the caudal body of the lateral meniscus was associated with degenerative osteoarthritis (OA) of the lateral compartment of the stifle. The Outerbridge score of the lateral tibial condyle and lateral femoral condyle was 5 of 5 in 15 dogs, 3 of 5 in 1 dog, and 4 of 5 in 1 dog. CONCLUSION: Dogs with complete tears of the lateral meniscus developed degenerative OA of the lateral compartment of the stifle leading to AC loss and clinical dysfunction. CLINICAL SIGNIFICANCE: Complete lateral meniscal tears may occur as isolated injuries in dogs with a functional CrCL.

Noise Exposure Questionnaire: A Tool for Quantifying Annual Noise Exposure.

BACKGROUND: Exposure to both occupational and nonoccupational noise is recognized as a risk factor for noise-induced hearing loss (NIHL). Although audiologists routinely inquire regarding history of noise exposure, there are limited tools available for quantifying this history or for identifying those individuals who are at highest risk for NIHL. Identifying those at highest risk would allow hearing conservation activities to be focused on those individuals. PURPOSE: To develop a detailed, task-based questionnaire for quantifying an individual's annual noise exposure (ANE) arising from both occupational and nonoccupational sources (aim 1) and to develop a short screening tool that could be used to identify individuals at high risk of NIHL (aim 2). RESEARCH DESIGN: Review of relevant literature for questionnaire development followed by a cross-sectional descriptive and correlational investigation of the newly developed questionnaire and screening tool. STUDY SAMPLE: One hundred fourteen college freshmen completed the detailed questionnaire for estimating ANE (aim 1) and answered the potential screening questions (aim 2). An additional 59 adults participated in data collection where the accuracy of the screening tool was evaluated (aim 2). DATA COLLECTION AND ANALYSIS: In study aim 1, all participants completed the detailed questionnaire and the potential screening questions. Descriptive statistics were used to quantify participant participation in various noisy activities and their associated ANE estimates. In study aim 2, linear regression techniques were used to identify screening questions that could be used to predict a participant's estimated ANE. Clinical decision theory was then used to assess the accuracy with which the screening tool predicted high and low risk of NIHL in a new group of participants. RESULTS: Responses on the detailed questionnaire indicated that our sample of college freshmen reported high rates of participation in a variety of occupational and nonoccupational activities associated with high sound levels. Although participation rates were high, ANE estimates were below highest-risk levels for many participants because the frequency of participation in these activities was low in many cases. These data illustrate how the Noise Exposure Questionnaire (NEQ) could be used to provide detailed and specific information regarding an individual's exposure to noise. The results of aim 2 suggest that the screening tool, the 1-Minute Noise Screen, can be used to identify those participants with high- and low-risk noise exposure, allowing more in-depth assessment of noise exposure history to be targeted at those most at risk. CONCLUSIONS: The NEQ can be used to estimate an individual's ANE and the 1-Minute Noise Screen can be used to identify those participants at highest risk of NIHL. These tools allow audiologists to focus hearing conservation efforts on those individuals who are most in need of those services.

Dark clouds or silver linings? A stigma threat perspective on the implications of an autism diagnosis for workplace well-being.

This article unpacks the stigma associated with a developmental disability at work, specifically autism spectrum disorders (ASD), by presenting findings from 2 studies-one interview-based and the other survey-based. Drawing on in-depth interviews with individuals on the autism spectrum, the first study showed that a clinical diagnosis of autism is a milestone event that triggered both positive (silver linings) and negative (dark clouds) responses to work. These positive and negative responses were shaped by the age at which the diagnosis occurred as well as specific work-related contingencies-identity management (disclosing or not disclosing), the importance of the social demands imposed by the job, and organizational support policies for autism. The second study developed and tested propositions derived from the qualitative data by using survey data gathered from working adults with ASD. Results showed that, compared with individuals diagnosed later in life, individuals who were diagnosed at an earlier age experienced greater organization-based self-esteem and lower perceived discrimination when they disclosed their disability, worked in jobs that placed lower social demands on them, or were employed in organizations that offered policies to support workers with ASD. We conclude that, depending on the age of diagnosis, attributes of the employment context can trigger stigma-related threat in different ways and we outline important practical implications of these findings.

Auditory function in normal-hearing, noise-exposed human ears.

OBJECTIVES: To determine whether suprathreshold measures of auditory function, such as distortion-product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs), are correlated with noise exposure history in normal-hearing human ears. Recent data from animal studies have revealed significant deafferentation of auditory nerve fibers after full recovery from temporary noise-induced hearing loss. Furthermore, these data report smaller ABR wave I amplitudes in noise-exposed animal ears when compared with non-noise-exposed control animals or prenoise exposure amplitudes in the same animal. It is unknown whether a similar phenomenon exists in the normal-hearing, noise-exposed human ear. DESIGN: Thirty normal-hearing human subjects with a range of noise exposure backgrounds (NEBs) participated in this study. NEB was quantified by the use of a noise exposure questionnaire that extensively queried loud sound exposure during the previous 12 months. DPOAEs were collected at three f2s (1, 2, and 4 kHz) over a range of L2s. DPOAE stimulus level began at 80 dB forward-pressure level and decreased in 10 dB steps. Two-channel ABRs were collected in response to click stimuli and 4 kHz tone bursts; one channel used an ipsilateral mastoid electrode and the other an ipsilateral tympanic membrane electrode. ABR stimulus level began at 90 dB nHL and was decreased in 10 dB steps. Amplitudes of waves I and V of the ABR were analyzed. RESULTS: A statistically significant relationship between ABR wave I amplitude and NEB was found for clicked-evoked ABRs recorded at a stimulus level of 90 dB nHL using a mastoid recording electrode. For this condition, ABR wave I amplitudes decreased as a function of NEB. Similar systematic trends were present for ABRs collected in response to clicks and 4 kHz tone bursts at additional suprathreshold stimulation levels (≥70 dB nHL). The relationship weakened and disappeared with decreases in stimulation level (≤60 dB nHL). Similar patterns were present for ABRs collected using a tympanic membrane electrode. However, these relationships were not statistically significant and were weaker and more variable than those collected using a mastoid electrode. In contrast to the findings for ABR wave I, wave V amplitude was not significantly related to NEB. Furthermore, there was no evidence of a systematic relationship between suprathreshold DPOAEs and NEB. CONCLUSIONS: A systematic trend of smaller ABR wave I amplitudes was found in normal-hearing human ears with greater amounts of voluntary NEB in response to suprathreshold clicks and 4 kHz tone bursts. These findings are consistent with the data from previous work completed in animals, where the reduction in suprathreshold responses was a result of deafferentation of high-threshold/low-spontaneous rate auditory nerve fibers. These data suggest that a similar mechanism might be operating in human ears after exposure to high sound levels. However, evidence of this damage is only apparent when examining suprathreshold wave I amplitude of the ABR. In contrast, suprathreshold DPOAE level was not significantly related to NEB. This was expected, given noise-induced auditory damage findings in animal ears did not extend to the outer hair cells, the generator for the DPOAE response.

Risk factors for self-injury, aggression, and stereotyped behavior among young children at risk for intellectual and developmental disabilities.

Before the 1990s, research on the early identification and prevention of severe behavior disorders (SBDs), such as aggression, self-injury, and stereotyped behavior, among young children with intellectual and developmental disabilities (IDD), was mostly done with children 3 years or older. More recent work suggests that signs of SBDs may occur as early as 6 months in some infants. The present study combined a cross-sectional and longitudinal approach to examine SBDs in 180 young children aged 4-48 months recruited through mass screening, then receiving an interdisciplinary evaluation and six-month follow-ups for one year. Twelve potential risk factors related to SBDs were examined. Eight of these risk factors, including age, gender, diagnosis, intellectual and communication levels, visual impairment, parent education, family income, were differentially related to scores for Aggression, SIB, and Stereotyped Behavior subscales on the Behavior Problems Inventory (BPI-01) at initial interdisciplinary evaluation. BPI-01 scores decreased over the year for 57% of the children and increased for 43%. The amount of decrease on each BPI-01 subscale varied with age, gender, and diagnosis.

Influence of stimulus parameters on amplitude-modulated stimulus frequency otoacoustic emissions.

The present study evaluated the influence of suppressor frequency (fs) and level (Ls) on stimulus-frequency otoacoustic emissions (SFOAEs) recorded using the amplitude-modulated (AM) suppressor technique described by Neely et al. [J. Acoust. Soc. Am. 118, 2124-2127 (2005a)]. Data were collected in normal-hearing subjects, with data collection occurring in two phases. In phase 1, SFOAEs were recorded with probe frequency (fp) = 1, 2, and 4 kHz and probe levels (Lp) ranging from 0 to 60 dB sound pressure level (SPL). At each fp, Ls ranged from Ls = Lp to Ls = Lp + 30 dB. Additionally, nine relationships between fs and fp were evaluated, ranging from fs/fp = 0.80 to fs/fp = 1.16. Results indicated that for low suppressor levels, suppressors higher in frequency than fp (fs > fp) resulted in higher AM-SFOAE levels than suppressors lower in frequency than fp (fs < fp). At higher suppressor levels, suppressors both higher and lower in frequency than fp produced similar AM-SFOAE levels, and, in many cases, low-frequency suppressors produced the largest response. Recommendations for stimulus parameters that maximize AM-SFOAE level were derived from these data. In phase 2, AM-SFOAEs were recorded using these parameters for fp = 0.7-8 kHz and Lp = 20-60 dB SPL. Robust AM-SFOAE responses were recorded in this group of subjects using the parameters developed in phase 1.

Phenotypic and Genotypic Characterization of Escherichia coli Isolated from Untreated Surface Waters.

A common member of the intestinal microbiota in humans and animals is Escherichia coli. Based on the presence of virulence factors, E. coli can be potentially pathogenic. The focus of this study was to isolate E. coli from untreated surface waters (37 sites) in Illinois and Missouri and determine phenotypic and genotypic diversity among isolates. Water samples positive for fecal coliforms based on the Colisure(®) test were streaked directly onto Eosin Methylene Blue (EMB) agar (37°C) or transferred to EC broth (44.5°C). EC broth cultures producing gas were then streaked onto EMB agar. Forty-five isolates were identified as E. coli using API 20E and Enterotube II identification systems, and some phenotypic variation was observed in metabolism and fermentation. Antibiotic susceptibility of each isolate was also determined using the Kirby-Bauer Method. Differential responses to 10 antimicrobial agents were seen with 7, 16, 2, and 9 of the isolates resistant to ampicillin, cephalothin, tetracycline, and triple sulfonamide, respectively. All of the isolates were susceptible or intermediate to amoxicillin, ciprofloxacin, polymyxin B, gentamicin, imipenem, and nalidixic acid. Genotypic variation was assessed through multiplex Polymerase Chain Reaction for four virulence genes (stx1 and stx2 [shiga toxin], eaeA [intimin]; and hlyA [enterohemolysin]) and one housekeeping gene (uidA [ß-D-glucuronidase]). Genotypic variation was observed with two of the isolates possessing the virulence gene (eaeA) for intimin. These findings increase our understanding of the diversity of E. coli in the environment which will ultimately help in the assessment of this organism and its role in public health.

The influence of common stimulus parameters on distortion product otoacoustic emission fine structure.

OBJECTIVES: To determine whether common approaches to setting stimulus parameters influence the depth of fine structure present in the distortion product otoacoustic emission (DPOAE) response. Because the presence of fine structure has been suggested as a possible source of errors, if one of the common parametric approaches results in reduced fine-structure depth, it may be preferred over other approaches. DESIGN: DPOAE responses were recorded in a group of 21 subjects with normal hearing for 1/3-octave intervals surrounding 3 f2s (1, 2, and 4 kHz) at three L2s (30, 45, and 55 dB SPL). For each f2 and L2 combination, L1 and f2/f1 were set according to three commonly used parametric approaches. These included a simple approach, the approach recommended by Kummer et al., and the approach described by Johnson et al. These three approaches primarily differ in the recommended relationship between L1 and L2. For each parametric approach, DPOAE fine structure was evaluated by varying f2 in small steps. Differences in DPOAE level and DPOAE fine-structure depth across f2, L2, and the various stimulus parameters were evaluated using repeated-measures analysis of variance. RESULTS: As expected, significant variations in DPOAE level were observed across the three parametric approaches. For stimulus levels #45 dB SPL, the simple stimuli resulted in lower DPOAE levels than were observed for other approaches. An unexpected finding was that stimulus parameters developed by Johnson et al., which were believed to produce higher DPOAE levels than other approaches, produced the lowest DPOAE levels of the three approaches when f2 = 4 kHz. Significant differences in fine-structure depth were also observed. Greater fine-structure depth was observed with the simple parameters, although this effect was restricted to L2 # 45 dB SPL. When L2 = 55 dB SPL, all three parametric approaches resulted in equivalent fine-structure depth. A significant difference in fine-structure depth across the 3 f2s was also observed. The interval surrounding 2 kHz was associated with greater fine-structure depth than the intervals surrounding 1 and 4 kHz. CONCLUSIONS: The simple stimulus parameters resulted in more fine structure than the other parametric approaches; however, this effect was restricted to L2 # 45 dB SPL. At the moderate stimulus levels used in most clinical applications of DPOAEs (L2 = 55 dB SPL), all three approaches resulted in similar fine-structure depths. These findings suggest that manipulating stimulus parameters, particularly the L1, L2 relationship, is not an effective technique for reducing fine structure, except at the lowest stimulus levels, and that all the common parameters result in equivalent fine structure for moderate stimulus levels. These results also suggest that the stimulus parameters used in future studies of the clinical implications of fine structure may be relatively unimportant, unless stimulus levels #45 dB SPL will be evaluated.

Monitoring biodegradation of ethene and bioremediation of chlorinated ethenes at a contaminated site using compound-specific isotope analysis (CSIA).

Chlorinated ethenes are commonly found in contaminated groundwater. Remediation strategies focus on transformation processes that will ultimately lead to nontoxic products. A major concern with these strategies is the possibility of incomplete dechlorination and accumulation of toxic daughter products (cis-1,2-dichloroethene (cDCE), vinyl chloride (VC)). Ethene mass balance can be used as a direct indicator to assess the effectiveness of dechlorination. However, the microbial processes that affect ethene are not well characterized and poor mass balance may reflect biotransformation of ethene rather than incomplete dechlorination. Microbial degradation of ethene is commonly observed in aerobic systems but fewer cases have been reported in anaerobic systems. Limited information is available on the isotope enrichment factors associated with these processes. Using compound-specific isotope analysis (CSIA) we determined the enrichment factors associated with microbial degradation of ethene in anaerobic microcosms (ε = -6.7‰ ± 0.4‰, and -4.0‰ ± 0.8‰) from cultures collected from the Twin Lakes wetland area at the Savannah River site in Georgia (United States), and in aerobic microcosms (ε = -3.0‰ ± 0.3‰) from Mycobacterium sp. strain JS60. Under anaerobic and aerobic conditions, CSIA can be used to determine whether biotransformation of ethene is occurring in addition to biodegradation of the chlorinated ethenes. Using δ(13)C values determined for ethene and for chlorinated ethenes at a contaminated field site undergoing bioremediation, this study demonstrates how CSIA of ethene can be used to reduce uncertainty and risk at a site by distinguishing between actual mass balance deficits during reductive dechlorination and apparent lack of mass balance that is related to biotransformation of ethene.

Cochlear sources and otoacoustic emissions.

Current understanding suggests that there are two different mechanisms by which otoacoustic emissions (OAEs) are generated in the cochlea. These mechanisms include a nonlinear-distortion mechanism and a coherent-reflection mechanism. Distortion product OAEs (DPOAEs) are believed to include contributions from both mechanisms, while stimulus frequency OAEs (SFOAES), at least at low and moderate levels, are believed to be generated primarily by the coherent-reflection mechanism. In the case of DPOAEs, the interaction of the two mechanisms produces a series of alternating peaks and valleys in the response level when recorded in small frequency increments. This pattern of peaks and valleys typically is referred to as fine structure. There has been much speculation that the interaction of the two mechanisms and the resulting fine structure limits the clinical test performance of DPOAEs. There are few data to address this speculation. Here, we review the literature that describes the cochlear source mechanisms and their potential relationship to clinical applications. We then present results for preliminary data collected in a group of 10 normal-hearing subjects where we explore the influence of common approaches to setting DPOAE stimulus parameters on the resulting fine structure. These preliminary results suggest that, at the moderate stimulus levels used in clinical applications, each of the different stimulus parameters results in a similar amount of fine structure and, therefore, fine structure cannot be eliminated through manipulation of stimulus parameters. We also review the results of some preliminary efforts to identify stimulus parameters that can be used to record SFOAEs (OAEs generated by the reflection mechanism). The potential clinical applications of SFOAEs have received little attention in the literature. By identifying stimulus parameters producing robust responses in normal-hearing ears, it may be possible to more fully evaluate clinical applications of SFOAEs.