Physician Assistants/Associates With Doctoral Degrees: Where Are They Now?

PURPOSE

The impact of holding a doctoral credential by clinically practicing physician assistants/associates (PAs) remains unknown. The purpose of this study was to investigate practice patterns and describe demographic characteristics of PAs who have terminal doctoral degrees.

METHODS

This was a secondary analysis of data obtained from the 2021 Salary Survey of the American Academy of PAs. A total of 13,865 PAs responded to the survey for an estimated response rate of 13.3%. We examined the relationships between holding a doctoral degree, demographic characteristics, and work-related variables. Descriptive bivariate statistics and chi-square tests were used for data analysis.

RESULTS

Most of the PAs (93.6%) with doctoral degrees were older than 30 years and self-identified as female (55%). There were higher proportions of non-White individuals among those with doctorates compared with general PA population. Of the PAs holding doctoral degrees, 90.4% were primarily clinicians and 9.6% were primarily educators. Physician assistants/associates with doctoral degrees were employed with their current employer longer than PAs without doctoral degrees. Most of the PAs with doctoral degrees held informal or formal leadership and had an annual salary above the median (62.3%) compared with PAs without doctoral degrees (40.0%).

CONCLUSION

There are statistically significant differences in practice patterns and demographic factors between PAs with and without doctoral degrees. Physician assistants/associates with doctoral degrees were older, were male, and held leadership positions. Taken together, holding a doctoral credential may improve upward mobility at workplaces. Qualitative studies are warranted to further understand the motivation and impact of holding a doctoral credential among clinically practicing PAs.

KMT2D Deficiency Causes Sensorineural Hearing Loss in Mice and Humans

Individuals with Kabuki syndrome type 1 (KS1) often have hearing loss recognized in middle childhood. Current clinical dogma suggests that this phenotype is caused by frequent infections due to the immune deficiency in KS1 and/or secondary to structural abnormalities of the ear. To clarify some aspects of hearing loss, we collected information on hearing status from 21 individuals with KS1 and found that individuals have both sensorineural and conductive hearing loss, with the average age of presentation being 7 years. Our data suggest that while ear infections and structural abnormalities contribute to the observed hearing loss, these factors do not explain all loss. Using a KS1 mouse model, we found hearing abnormalities from hearing onset, as indicated by auditory brainstem response measurements. In contrast to mouse and human data for CHARGE syndrome, a disorder possessing overlapping clinical features with KS and a well-known cause of hearing loss and structural inner ear abnormalities, there are no apparent structural abnormalities of the cochlea in KS1 mice. The KS1 mice also display diminished distortion product otoacoustic emission levels, which suggests outer hair cell dysfunction. Combining these findings, our data suggests that KMT2D dysfunction causes sensorineural hearing loss compounded with external factors, such as infection.

Impact of post-incarceration care engagement interventions on HIV transmission among young Black men who have sex with men and their sexual partners: an agent-based network modeling study

Background

Understanding the impact of incarceration on HIV transmission among Black men who have sex with men is important given their disproportionate representation among people experiencing incarceration and the potential impact of incarceration on social and sexual networks, employment, housing, and medical care. We developed an agent-based network model (ABNM) of 10,000 agents representing young Black men who have sex with men in the city of Chicago to examine the impact of varying degrees of post-incarceration care disruption and care engagement interventions following release from jail on HIV incidence.

Methods

Exponential random graph models were used to model network formation and dissolution dynamics, and network dynamics and HIV care continuum engagement were varied according to incarceration status. Hypothetical interventions to improve post-release engagement in HIV care for individuals with incarceration (e.g., enhanced case management, linkage to housing and employment services) were compared to a control scenario with no change in HIV care engagement after release.

Finding

HIV incidence at 10 years was 4.98 [95% simulation interval (SI): 4.87, 5.09 per 100 person-years (py)] in the model population overall; 5.58 (95% SI 5.38, 5.76 per 100 py) among those with history of incarceration, and 12.86 (95% SI 11.89, 13.73 per 100 py) among partners of agents recently released from incarceration. Sustained post-release HIV care for agents with HIV and experiencing recent incarceration resulted in a 46% reduction in HIV incidence among post-incarceration partners [incidence rate (IR) per 100 py = 5.72 (95% SI 5.19, 6.27) vs. 10.61 (95% SI 10.09, 11.24); incidence rate ratio (IRR) = 0.54; (95% SI 0.48, 0.60)] and a 19% reduction in HIV incidence in the population overall [(IR per 100 py = 3.89 (95% SI 3.81-3.99) vs. 4.83 (95% SI 4.73, 4.92); IRR = 0.81 (95% SI 0.78, 0.83)] compared to a scenario with no change in HIV care engagement from pre-to post-release.

Interpretation

Developing effective and scalable interventions to increase HIV care engagement among individuals experiencing recent incarceration and their sexual partners is needed to reduce HIV transmission among Black men who have sex with men.

Funding

This work was supported by the following grants from the National Institutes of Health: R01DA039934; P20 GM 130414; P30 AI 042853; P30MH058107; T32 DA 043469; U2C DA050098 and the California HIV/AIDS Research Program: OS17-LA-003; H21PC3466.

Assessing Food Access, Exercise, and Dietary History among Older African American Parishioners During the COVID-19 Pandemic (C-FED Study): Design, Opportunities, Challenges, and Lessons Learned

OBJECTIVES

Unhealthy diets and inadequate exercise are associated with chronic health conditions and excess mortality. Older African Americans do not meet dietary and exercise guidelines, and this may have worsened during the COVID-19 pandemic due to individual and environmental factors, including food insecurity. Studies evaluating these dynamics are essential for developing interventions. This narrative details a study protocol and data collection experiences during the pandemic.

METHODS

Participants > 55 years African American old completed detailed food frequency, exercise, and food access questionnaires between October 2020 and July 2021. Observations of the study administrators (authors of this manuscript) for the duration of the study are presented. Details on the study design and reflections on the opportunities, challenges, and lessons learned are summarized. Future manuscripts will report data analysis of study findings.

RESULTS

A total of 123 older African American adults participated in the study, and 118 (70% female) completed all three questionnaires. More than 50% of the participants had at least two primary chronic conditions. About 85% were fully vaccinated against COVID-19. Applying community-based participatory approaches, leveraging partnerships, and exercising flexibility approaches were pivotal to successfully implementing the study protocol.

CONCLUSIONS

Despite challenges related to the COVID-19 pandemic, detailed data on older African American adults' diet and exercise habits were obtained. Our study design and experiences will benefit future researchers. More importantly, results from our study will inform interventions and policies aimed at minimizing consequences associated with poor diet and exercise habits during the pandemic among this vulnerable population.

Diet Quality of Older African Americans: Impact of Knowledge and Perceived Threat of COVID-19

Confusing health messages and environmental changes intended to prevent the spread of the COVID-19 virus have affected the dietary behavior of older African Americans. We investigated the impact of COVID-19-related factors on diet quality and the relationship between food access and diet quality. We surveyed 150 African Americans aged 55 years and above during the COVID-19 pandemic. The data obtained included socio-demographic and health information, and COVID-19-related knowledge and perceptions. Dietary intake data was obtained using the Diet History Questionnaire III. Analyses included bivariate and multivariable statistics. Overall, based on United States Department of Agriculture guidelines, the diet quality of older African Americans was poor. Lower knowledge and a lower perceived threat of COVID-19 were significantly associated with poor diet quality. Additionally, older African Americans with chronic diseases and food insecurity had poor diet quality. The COVID-19 pandemic has highlighted the fragility of diet quality. The combined impact of poor knowledge and perceived threat of COVID-19, chronic disease, and food insecurity contribute to poor diet quality in this population. This study adds to the well-known need for strategies to support the right to a healthy diet, particularly during COVID-19 and future pandemics. Proactive interventions to counteract the potential consequences of poor diets are needed.

Reducing Human Immunodeficiency Virus and Sexually Transmitted Infections Risk in African American Women with At-Risk Male Partners: A Randomized Trial

Background: We examined the efficacy of the Females of African American Legacy Empowering Self (FemAALES) intervention in a cohort of 203 publicly insured Black women in Los Angeles. Materials and Methods: Women who reported recent sex with a male partner who was at increased risk for infection by human immunodeficiency virus (HIV) and sexually transmitted infections (STI) were randomized to the six-session FemAALES intervention or to a single client-centered family planning and STI/HIV counseling session. Participants were followed at 3 and 9 months post-intervention. To investigate between-group behavioral changes in condomless sex in the prior 90 days and other HIV/STI risks, we used generalized estimating equations that accounted for repeated observations in individuals. Results: Most participants (mean age 34 ± 11 standard deviation) were low-income and unemployed, despite three-quarters having completed high school or the equivalent. The most common HIV/STI risk factors among recent male partners were incarceration (58.8%) and concurrent sex with other women (72.2%). At 3 months, the FemAALEs group showed a larger increase in the odds of asking their partner to test (adjusted odds ratio = 2.14; 95% confidence interval [CI], 1.02-4.47; p = 0.0431) and in sexual health self-efficacy scores (adjβ = 1.82; 95% CI, 0.02-3.62; p = 0.0471) compared to the control group, although these changes did not hold at 9 months. Both groups showed statistically significant declines in the frequency of several sexual risk factors between baseline and 9 months. Conclusion: Although we did not find evidence that the FemAALES intervention was more efficacious than the less-intensive control condition in reducing sexual risk behaviors, the overall declines in risk behaviors we observed warrant further research. ClinicalTrials.gov (Identifier: NCT02189876).

Racial/ethnic and gender disparity in the severity of NAFLD among people with diabetes or prediabetes

Aim: Non-alcoholic fatty liver disease (NAFLD) exhibits a racial disparity. We examined the prevalence and the association between race, gender, and NAFLD among prediabetes and diabetes populations among adults in the United States. Methods: We analyzed data for 3,190 individuals ≥18 years old from the National Health and Nutrition Examination Survey (NHANES) 2017-2018. NAFLD was diagnosed by FibroScan^® using controlled attenuation parameter (CAP) values: S0 (none) < 238, S1 (mild) = 238-259, S2 (moderate) = 260-290, S3 (severe) > 290. Data were analyzed using Chi-square test and multinomial logistic regression, adjusting for confounding variables and considering the design and sample weights. Results: Of the 3,190 subjects, the prevalence of NAFLD was 82.6%, 56.4%, and 30.5% (p < 0.0001) among diabetes, prediabetes and normoglycemia populations respectively. Mexican American males with prediabetes or diabetes had the highest prevalence of severe NAFLD relative to other racial/ethnic groups (p < 0.05). In the adjusted model, among the total, prediabetes, and diabetes populations, a one unit increase in HbA1c was associated with higher odds of severe NAFLD [adjusted odds ratio (AOR) = 1.8, 95% confidence level (CI) = 1.4-2.3, p < 0.0001; AOR = 2.2, 95% CI = 1.1-4.4, p = 0.033; and AOR = 1.5, 95% CI = 1.1-1.9, p = 0.003 respectively]. Conclusion: We found that prediabetes and diabetes populations had a high prevalence and higher odds of NAFLD relative to the normoglycemic population and HbA1c is an independent predictor of NAFLD severity in prediabetes and diabetes populations. Healthcare providers should screen prediabetes and diabetes populations for early detection of NAFLD and initiate treatments including lifestyle modification to prevent the progression to non-alcoholic steatohepatitis or liver cancer.

Sources of variability in auditory brainstem response thresholds in a mouse model of noise-induced hearing loss

Numerous and non-acoustic experimental factors can potentially influence experimental outcomes in animal models when measuring the effects of noise exposures. Subject-related factors, including species, strain, age, sex, body weight, and post-exposure measurement timepoints, influence the observed hearing deficits. Experimenter effects, such as experience with experimental techniques and animal handling, may also factor into reported thresholds. In this study, the influence of subject sex, body mass, age at noise exposure, and timepoint of post-exposure recording are reported from a large sample of CBA/CaJ mice. Auditory brainstem response (ABR) thresholds differed between noise-exposed and unexposed mice, although the differences varied across tone frequencies. Thresholds across age at noise exposures and measurement delays after exposure also differed for some timepoints. Higher body mass correlated with higher ABR thresholds for unexposed male and female mice, but not for noise-exposed mice. Together, these factors may contribute to differences in phenotypic outcomes observed across studies or even within a single laboratory.

Academic leadership in physician assistant/associate medical education: a cross-sectional analysis of the association with doctoral degree, gender, and minority status

BACKGROUND

There is a critical need for a diverse pool of academic leaders to increase the number and diversity of the medical workforce. Physician Assistant/Associate (PA) is a growing medical profession. Although the master's degree is the terminal degree for PAs, a growing number of PAs obtain a variety of doctoral degrees. However, there is no standardized training for academic PA leaders. The purpose of this study was to identify factors associated with PA academic leadership. Specifically, this study explored the following factors: doctoral degree credentials, gender and underrepresented minority status.

METHODS

Using the 2019 Physician Assistant Education Association Faculty and Directors survey, we assessed the relationship between academic leadership groups [Program Director (PD), Academic Director (AD), and Clinical Director (CD)] doctoral degree, gender, and underrepresented minority in medicine (URIM) status. Multivariable logistic regression models were used to determine the predictors of being in a leadership role. Results with p < 0.05 were considered statistically significant.

RESULTS

Of the 956 participants, 71% were female, 4% Hispanic, 86% White, 4% Black, 2% Asian, and 1% Native Hawaiian/Pacific Islander/American Indian/Alaska Native. Overall, 9% were URIM. Mean age was 45.6 (SD = 10.2) years. Average time in PA education was 2.9 years (SD = 1.4). Approximately 50% (n = 472) had a leadership role (PD-24%, AD-10%, CD-16%). Of all leaders, 68% were female, 9% were URIM, and 19% had a doctoral degree. Having a doctoral degree increased the odds of being a PD [AOR 2.38, CI [1.57-3.59], p = < 0.0001, AD and CD = non-significant]. More time in PA education increased the odds of being a PD [AOR 1.10, CI [1.07-1.12, p = < 0.0001] and AD [AOR 1.06, CI [1.03-1.09], p = < 0.0001], but not a CD. Gender and URIM status were not significantly associated with leadership roles. URIMs had doctorate degrees at higher rates than non-URIMs.

CONCLUSION

PA academic leaders differ by doctoral degree attainment but not by gender and URIM status. URIM faculty are grossly underrepresented in the PA professorate, but disproportionately have doctoral degrees. Academic training opportunities for all PA academic leaders and strategies to increase URIM faculty are needed.

Auditory Behavior in Adult-Blinded Mice

Cross-modal plasticity occurs when the function of remaining senses is enhanced following deprivation or loss of a sensory modality. Auditory neural responses are enhanced in the auditory cortex, including increased sensitivity and frequency selectivity, following short-term visual deprivation in adult mice (Petrus et al. Neuron 81:664-673, 2014). Whether or not these visual deprivation-induced neural changes translate into improved auditory perception and performance remains unclear. As an initial investigation of the effects of adult visual deprivation on auditory behaviors, CBA/CaJ mice underwent binocular enucleation at 3-4 weeks old and were tested on a battery of learned behavioral tasks, acoustic startle response (ASR), and prepulse inhibition (PPI) tests beginning at least 2 weeks after the enucleation procedure. Auditory brain stem responses (ABRs) were also measured to screen for potential effects of visual deprivation on non-behavioral hearing function. Control and enucleated mice showed similar tone detection sensitivity and frequency discrimination in a conditioned lick suppression test. Both groups showed normal reactivity to sound as measured by ASR in a quiet background. However, when startle-eliciting stimuli were presented in noise, enucleated mice showed decreased ASR amplitude relative to controls. Control and enucleated mice displayed no significant differences in ASR habituation, PPI tests, or ABR thresholds, or wave morphology. Our findings suggest that while adult-onset visual deprivation induces cross-modal plasticity at the synaptic and circuit levels, it does not substantially influence simple auditory behavioral performance.

Factors predicting incarceration history and incidence among Black and Latino men who have sex with men (MSM) residing in a major urban center

We analyzed data from a cohort of Black and Latino men who have sex with men (MSM) in order to identify correlates of prevalent and incident incarceration, including potential predictors related to their status as sexual and gender minorities (SGMs). Baseline and follow-up self-administered survey data were examined from Los Angeles County participants' ages 18-45 years at enrollment who were either HIV negative or living with HIV, but recruited to over represent men who used drugs and men with unsuppressed HIV infection. Multivariable logistic regression models were developed to identify predictors of baseline incarceration history and of incident incarceration over study follow-up among 440 and 338 participants, respectively. Older age, Black race, low socioeconomic status, homelessness, stimulant use, and depression symptoms were associated with baseline incarceration history. The only SGM-related factor associated with baseline incarceration history was having experienced violence based on sexual orientation identity. Just one statistically significant, independent positive predictor of incident incarceration was identified: prior incarceration, whereas having four or more friends that could lend money was a statistically significant protective factor against incident incarceration. Fundamental Cause Theory provides a useful framework to explain identified predictors of incarceration. Addressing poverty, housing instability, inadequate access to health care, and their root causes is critical to reducing incarceration rates in this population, as is expanded access to both diversion and anti-recidivism programs and to evidence-based treatment for stimulant use disorders.

Sex-Specific Differences in the Association Between Race/Ethnicity and NAFLD Among US Population

Non-alcoholic fatty liver disease (NAFLD) is spreading worldwide, with a racial/ethnic disparity. We examined the gender role in the racial/ethnic difference in NAFLD in the US population. We analyzed data for 3,292 individuals ≥18 years old from NHANES 2017-2018, a representative sample of the non-institutionalized adult population in the US. Exclusions were subjects with elevated transferrin level, chronic hepatitis B or C, excessive alcohol use, or prescription medications that might cause hepatic steatosis. NAFLD was diagnosed by FibroScan^® using controlled attenuation parameter (CAP) values: S0 <238, S1 = 238-259, S2 = 260-290, S3 >290. Data were analyzed using Chi square and multinomial regression. The overall prevalence of NAFLD was 47.9% [S2 = 16.1%, and S3 = 31.8%]. The prevalence of S3 was highest among Mexican Americans (46%), lowest among Blacks (22.7%), 29.9% in other Hispanics and 32.1% in Whites (p < 0.05). It was higher among Mexican American males (54.1%) compared to Mexican American females (37.7%) (p < 0.05). In the adjusted model, Mexican Americans were two times more likely than Whites to have S2 and S3 (p < 0.05). Only male Mexican Americans had higher odds of S2 and S3 relative to male White (p < 0.05). Males had higher odds of S3 relative to non-menopausal females (p < 0.05). There was no difference in the odds of S2 or S3 NAFLD among the menopausal females with or without hormone therapy relative to non-menopausal females (p > 0.05). While Mexican Americans had the highest prevalence of severe NAFLD relative to the other racial/ethnic groups, only male Mexican Americans, but not females, had higher likelihood of both moderate and severe NAFLD relative to Whites. Interventions that specifically target Mexican American males are needed to increase awareness about NAFLD and its prevention.

Reassessment of the Hispanic Disparity: Hepatic Steatosis Is More Prevalent in Mexican Americans Than Other Hispanics

Hepatic steatosis (HS) is a growing problem in adults worldwide, with racial/ethnic disparity in the prevalence of the disease. The purpose of this study was to characterize the racial/ethnic prevalence of the stages (normal/mild [S0/S1], moderate [S2], and severe [S3]) of HS in Mexican Americans and other Hispanics compared to other racial/ethnic groups. We analyzed data for 5,492 individuals 12 years and older from the newly released National Health and Nutrition Examination Survey 2017-2018, which is a representative sample of the US adult population. HS was diagnosed by FibroScan using controlled attenuation parameter values: S0, <238; S1, 238-259; S2, 260-290; S3, >290. We analyzed the data using the bivariate chi-squared test and multinomial regression. The prevalence of HS overall was 46.9% (S2,16.6%; S3, 30.3%). The prevalence of S3 was highest among Mexican Americans (42.8%), lowest among Blacks (21.6%), 27.6% in other Hispanics, and 30.6% in Whites (P < 0.05). Mexican Americans were about 2 times more likely than Whites to have S2 and S3, while other Hispanics showed no difference from Whites. In an adjusted model, the common risk factors of S2 and S3 were male sex, older ages, high waist-to-hip ratio, body mass index ≥25, and high triglycerides (P < 0.05). Other risk factors for S3 were hemoglobin A1c ≥5.7 and highly sensitive C-reactive protein ≥10 mg/dL (P < 0.05). Conclusion: Our study challenges the paradigm that HS is higher in Hispanics overall; rather, our data show that HS is higher in Mexican Americans and not non-Mexican American Hispanics.

Dietary quality, food security and glycemic control among adults with diabetes

BACKGROUND AND AIMS

Nutritionally adequate diets can slow the progression of diabetes, but adherence to recommended dietary choices can be hindered by food insecurity. We examined the relationship between dietary quality, food insecurity, and glycemic control among adults with Type 2 Diabetes.

METHODS

We analyzed data from the National Health and Nutrition Examination Survey (2011-2016) for 1682 adults =>20 years old with Type 2 diabetes. Glycemic control was measured by HbA1c. Dietary quality was computed using the Healthy Eating Index 2015 score. Food security was assessed by a questionnaire. We analyzed the data using multinomial regression models.

RESULTS

About 16% of the population had an HbA1c ≥ 9; 31.8% had food insecurity; 68.3% consumed a poor quality diet. About 24% consumed a poor quality diet and had food insecurity. In the multinomial model, an HbA1c of 8-<9% was associated with poor diet quality (adjusted odds ratio (AOR) = 5.2, 95% confidence interval (CI) = 1.4-19.2, p = 0.01) and food insecurity (AOR = 8.5, 95% CI = 1.4-52.0, p = 0.02). Those with both factors had higher odds of both an HbA1c 8-<9% (AOR = 6.1, 95% CI = 1.5-24.8, p = 0.01) and HbA1c ≥ 9% (AOR = 6.7, 95% CI = 2.0-22.2, p < 0.01). Other risk factors for poor glycemic control were being Black or Hispanic, having no regular source of care, and ever having visited a diabetes specialist (p < 0.05).

CONCLUSIONS

Poor glycemic control among adults with diabetes was associated with poor quality of diet and/or food insecurity, being Black, Hispanic, and lacking a regular source of care. There is a need for policies that improve access to healthy food in patients with type 2 diabetes, particularly among minority populations.

Deafness in an auditory specialist, the big brown bat (Eptesicus fuscus)

Bats are long-lived animals that show presumed resistance to noise-induced and age-related hearing loss, which has been attributed to their dependence on sound processing for survival. Echolocation and basic auditory functions have been studied extensively in the big brown bat (Eptesicus fuscus), an insectivorous microchiropteran species. We conducted hearing tests and analysis of cochlear sensory cells in a group of big brown bats that exhibited anomalies in behavioral sonar tracking experiments and/or lacked neural responses to acoustic stimulation in subcortical auditory nuclei. We show for the first time the presence of profound deafness and extensive cochlear damage in an echolocating bat species. Auditory brainstem responses were abnormal or absent in these bats, and histological analyses of their cochleae revealed extensive loss of hair cells, supporting cells, and spiral ganglion neurons. The underlying cause of deafness is unknown.

Lung mediated auditory contrast enhancement improves the Signal-to-noise ratio for communication in frogs

Environmental noise is a major source of selection on animal sensory and communication systems. The acoustic signals of other animals represent particularly potent sources of noise for chorusing insects, frogs, and birds, which contend with a multi-species analog of the human "cocktail party problem" (i.e., our difficulty following speech in crowds). However, current knowledge of the diverse adaptations that function to solve noise problems in nonhuman animals remains limited. Here, we show that a lung-to-ear sound transmission pathway in frogs serves a heretofore unknown noise-control function in vertebrate hearing and sound communication. Inflated lungs improve the signal-to-noise ratio for communication by enhancing the spectral contrast in received vocalizations in ways analogous to signal processing algorithms used in hearing aids and cochlear implants. Laser vibrometry revealed that the resonance of inflated lungs selectively reduces the tympanum's sensitivity to frequencies between the two spectral peaks present in conspecific mating calls. Social network analysis of continent-scale citizen science data on frog calling behavior revealed that the calls of other frog species in multi-species choruses can be a prominent source of environmental noise attenuated by the lungs. Physiological modeling of peripheral frequency tuning indicated that inflated lungs could reduce both auditory masking and suppression of neural responses to mating calls by environmental noise. Together, these data suggest an ancient adaptation for detecting sound via the lungs has been evolutionarily co-opted to create auditory contrast enhancement that contributes to solving a multi-species cocktail party problem.

Prevalence and Predictors of Nonalcoholic Steatohepatitis Using Multiple Non-Invasive Methods: Data from NHANES III

Objective

Patients with nonalcoholic steatohepatitis (NASH) are at risk for developing cirrhosis and hepatic cancer. Currently, the definitive gold-standard method of diagnosing NASH is a liver biopsy, an invasive and costly method. Our objective was to compare three non-invasive methods of identifying NASH by using data on 10,007 subjects from NHANES III (1988-1994) to determine the prevalence and variables associated with NASH, as defined by each non-invasive method.

Methods

We used ultrasound data to identify subjects with moderate-to-severe hepatic steatosis, of whom we identified the NASH population using either the HAIR score, the NASH liver fat score, or the Gholam score, each of which had been validated with liver biopsy. We performed multinomial logistic regression to compare each NASH population to the normal population (those with no-to-mild hepatic steatosis).

Results

We identified 1136 (9.5%) subjects as having NASH by at least one method and 219 (1.8%) were identified by all 3 methods. Independent of the non-invasive method used, Mexican-Americans (MA) had the highest prevalence of NASH. All three methods identified significant risk factors for NASH (p<0.05), including: elevated waist-to-hip ratio, elevated levels of C-peptide, total cholesterol, or C-reactive protein (CRP).

Conclusion

We conclude that the combined non-invasive methods can help identify candidates with a high likelihood of being diagnosed with NASH. Health care providers can screen people with the combined non-invasive methods for the risk factors and identify candidates for interventions, including exercise and/or referral to biopsy.

Functional, Morphological, and Evolutionary Characterization of Hearing in Subterranean, Eusocial African Mole-Rats

Naked mole-rats are highly vocal, eusocial, subterranean rodents with, counterintuitively, poor hearing. The causes underlying their altered hearing are unknown. Moreover, whether altered hearing is degenerate or adaptive to their unique lifestyles is controversial. We used various methods to identify the factors contributing to altered hearing in naked and the related Damaraland mole-rats and to examine whether these alterations result from relaxed or adaptive selection. Remarkably, we found that cochlear amplification was absent from both species despite normal prestin function in outer hair cells isolated from naked mole-rats. Instead, loss of cochlear amplification appears to result from abnormal hair bundle morphologies observed in both species. By exploiting a well-curated deafness phenotype-genotype database, we identified amino acid substitutions consistent with abnormal hair bundle morphology and reduced hearing sensitivity. Amino acid substitutions were found in unique groups of six hair bundle link proteins. Molecular evolutionary analyses revealed shifts in selection pressure at both the gene and the codon level for five of these six hair bundle link proteins. Substitutions in three of these proteins are associated exclusively with altered hearing. Altogether, our findings identify the likely mechanism of altered hearing in African mole-rats, making them the only identified mammals naturally lacking cochlear amplification. Moreover, our findings suggest that altered hearing in African mole-rats is adaptive, perhaps tailoring hearing to eusocial and subterranean lifestyles. Finally, our work reveals multiple, unique evolutionary trajectories in African mole-rat hearing and establishes species members as naturally occurring disease models to investigate human hearing loss.

Linking anatomical and physiological markers of auditory system degeneration with behavioral hearing assessments in a mouse (Mus musculus) model of age-related hearing loss

Age-related hearing loss is a very common sensory disability, affecting one in three older adults. Establishing a link between anatomical, physiological, and behavioral markers of presbycusis in a mouse model can improve the understanding of this disorder in humans. We measured age-related hearing loss for a variety of acoustic signals in quiet and noisy environments using an operant conditioning procedure and investigated the status of peripheral structures in CBA/CaJ mice. Mice showed the greatest degree of hearing loss in the last third of their lifespan, with higher thresholds in noisy than in quiet conditions. Changes in auditory brainstem response thresholds and waveform morphology preceded behavioral hearing loss onset. Loss of hair cells, auditory nerve fibers, and signs of stria vascularis degeneration were observed in old mice. The present work underscores the difficulty in ascribing the primary cause of age-related hearing loss to any particular type of cellular degeneration. Revealing these complex structure-function relationships is critical for establishing successful intervention strategies to restore hearing or prevent presbycusis.

Small Randomized Controlled Trial of the New Passport to Wellness HIV Prevention Intervention for Black Men Who Have Sex With Men (BMSM)

We developed and tested Passport to Wellness (PtW), a client-centered intervention to improve engagement in HIV/STI prevention and services to improve social determinants of health among Black men who have sex with men (BMSM) using incentives and peer support. We assessed PtW's impact on HIV/STI screening and pre/post-exposure prophylaxis (PrEP/PEP) knowledge/uptake using a randomized trial that compared the full intervention to one lacking peer support. We compared changes within groups surveyed at baseline and 6 months. We enrolled 80 eligible BMSM, among 399 screened. Among retained participants (34 peer-supported; 27 comparison), overall increases were observed in HIV (30% to 87%; p < .001) and STI (28% to 80%; p < .001) testing within the prior 6 months, as well as in PrEP and PEP awareness, and PrEP use. Statistically significant between group differences were not observed. Tailored prevention planning, incentives, and addressing social determinants may help move Black MSM along the HIV prevention continuum.

Cross-Modal Reinstatement of Thalamocortical Plasticity Accelerates Ocular Dominance Plasticity in Adult Mice

Plasticity of thalamocortical (TC) synapses is robust during early development and becomes limited in the adult brain. We previously reported that a short duration of deafening strengthens TC synapses in the primary visual cortex (V1) of adult mice. Here, we demonstrate that deafening restores NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) of TC synapses onto principal neurons in V1 layer 4 (L4), which is accompanied by an increase in NMDAR function. In contrast, deafening did not recover long-term depression (LTD) at TC synapses. Potentiation of TC synapses by deafening is absent in parvalbumin-positive (PV+) interneurons, resulting in an increase in feedforward excitation to inhibition (E/I) ratio. Furthermore, we found that a brief duration of deafening adult mice recovers rapid ocular dominance plasticity (ODP) mainly by accelerating potentiation of the open-eye responses. Our results suggest that cross-modal sensory deprivation promotes adult cortical plasticity by specifically recovering TC-LTP and increasing the E/I ratio.

Plasticity of thalamocortical (TC) synapses is limited in adults. Rodríguez et al. demonstrate that a brief period of deafening adults recovers LTP at TC synapses in visual cortex and accelerates ocular dominance plasticity. These results suggest that cross-modal sensory deprivation may be an effective way to promote adult cortical plasticity.

Sex bias in basic and preclinical age-related hearing loss research

Objectives

This study aims to determine if there is sex bias in basic and preclinical research on age-related hearing loss for the 10-year period of 2006–2015, prior to the NIH mandate of including sex as a biological variable in 2016.

Design

Manuscripts were identified in PubMed for the query “age-related hearing loss” for the 10-year period of 2006 to 2015. Manuscripts were included if they were original research (not reviews or meta-analyses), written in English, contained an abstract, used animals, and were primarily on age-related hearing loss. These criteria yielded 231 unique manuscripts for inclusion in the study analysis. The text of each manuscript was screened for the sex of the animals, the number of male and female animals, the discussion of sex-based results, the study site (US or international), and the year of publication.

Results

Only two thirds of manuscripts reported the sex of animals used in the experiments, and of these, 54% used both sexes, 34% used males only, and 13% used females only. In papers reporting sex and number of animals used, 67% were males and 33% were females. Over twice as many internationally based studies used males only compared to US-based studies. Only 15% of all manuscripts discussed sex-based results.

Conclusions

Sex bias is present in basic and preclinical age-related hearing loss research for the manuscripts screened in the 10-year period. Equal inclusion of both males and females in basic and preclinical age-related hearing loss research is critical for understanding sex-based differences in mechanisms and for effective treatment options.

Evolutionary adaptations for the temporal processing of natural sounds by the anuran peripheral auditory system

Sensory systems function most efficiently when processing natural stimuli, such as vocalizations, and it is thought that this reflects evolutionary adaptation. Among the best-described examples of evolutionary adaptation in the auditory system are the frequent matches between spectral tuning in both the peripheral and central auditory systems of anurans (frogs and toads) and the frequency spectra of conspecific calls. Tuning to the temporal properties of conspecific calls is less well established, and in anurans has so far been documented only in the central auditory system. Using auditory-evoked potentials, we asked whether there are species-specific or sex-specific adaptations of the auditory systems of gray treefrogs (Hyla chrysoscelis) and green treefrogs (H. cinerea) to the temporal modulations present in conspecific calls. Modulation rate transfer functions (MRTFs) constructed from auditory steady-state responses revealed that each species was more sensitive than the other to the modulation rates typical of conspecific advertisement calls. In addition, auditory brainstem responses (ABRs) to paired clicks indicated relatively better temporal resolution in green treefrogs, which could represent an adaptation to the faster modulation rates present in the calls of this species. MRTFs and recovery of ABRs to paired clicks were generally similar between the sexes, and we found no evidence that males were more sensitive than females to the temporal modulation patterns characteristic of the aggressive calls used in male-male competition. Together, our results suggest that efficient processing of the temporal properties of behaviorally relevant sounds begins at potentially very early stages of the anuran auditory system that include the periphery.

Assessing stimulus and subject influences on auditory evoked potentials and their relation to peripheral physiology in green treefrogs (Hyla cinerea)

Anurans (frogs and toads) are important models for comparative studies of communication, auditory physiology, and neuroethology, but to date, most of our knowledge comes from in-depth studies of a relatively small number of model species. Using the well-studied green treefrog (Hyla cinerea), this study sought to develop and evaluate the use of auditory evoked potentials (AEPs) as a minimally invasive tool for investigating auditory sensitivity in a larger diversity of anuran species. The goals of the study were to assess the effects of frequency, signal level, sex, and body size on auditory brainstem response (ABR) amplitudes and latencies, characterize gross ABR morphology, and generate an audiogram that could be compared to several previously published audiograms for green treefrogs. Increasing signal level resulted in larger ABR amplitudes and shorter latencies, and these effects were frequency dependent. There was little evidence for an effect of sex or size on ABRs. Analyses consistently distinguished between responses to stimuli in the frequency ranges of the three previously-described populations of afferents that innervate the two auditory end organs in anurans. The overall shape of the audiogram shared prominent features with previously published audiograms. This study highlights the utility of AEPs as a valuable tool for the study of anuran auditory sensitivity.

Spatial hearing in Cope's gray treefrog: II. Frequency-dependent directionality in the amplitude and phase of tympanum vibrations

Anuran ears function as pressure difference receivers, and the amplitude and phase of tympanum vibrations are inherently directional, varying with sound incident angle. We quantified the nature of this directionality for Cope's gray treefrog, Hyla chrysoscelis. We presented subjects with pure tones, advertisement calls, and frequency-modulated sweeps to examine the influence of frequency, signal level, lung inflation, and sex on ear directionality. Interaural differences in the amplitude of tympanum vibrations were 1-4 dB greater than sound pressure differences adjacent to the two tympana, while interaural differences in the phase of tympanum vibration were similar to or smaller than those in sound phase. Directionality in the amplitude and phase of tympanum vibration were highly dependent on sound frequency, and directionality in amplitude varied slightly with signal level. Directionality in the amplitude and phase of tone- and call-evoked responses did not differ between sexes. Lung inflation strongly affected tympanum directionality over a narrow frequency range that, in females, included call frequencies. This study provides a foundation for further work on the biomechanics and neural mechanisms of spatial hearing in H. chrysoscelis, and lends valuable perspective to behavioral studies on the use of spatial information by this species and other frogs.

A method for conducting functional MRI studies in alert nonhuman primates: initial results with opioid agonists in male cynomolgus monkeys

Functional MRI (fMRI) has emerged as a powerful technique for assessing neural effects of psychoactive drugs and other stimuli. Several experimental approaches have been developed to use fMRI in anesthetized and awake animal subjects, each of which has its advantages and complexities. We sought to assess whether one particular method to scan alert postanesthetized animals can be used to assess fMRI effects of opioid agonists. To date, the use of fMRI as a method to compare pharmacological effects of opioid drugs has been limited. Such studies are important because mu and kappa opioid receptor agonists produce distinct profiles of behavioral effects related both to clinically desirable endpoints (e.g., analgesia) and to undesirable effects (e.g., abuse potential). This study sought to determine whether we could use our fMRI approach to compare acute effects of behaviorally equipotent (3.2 μg/kg) intravenous doses of fentanyl and U69,593 (doses that do not affect cardiorespiratory parameters). Scans were acquired in alert male cynomolgus macaques acclimated to undergo fMRI scans under restraint, absent excessive stress hormone increases. These opioid agonists activated bilateral striatal and nucleus accumbens regions of interest. At the dose tested, U69,593 induced greater left nucleus accumbens BOLD activation than fentanyl, while fentanyl activated left dorsal caudate nucleus more than U69,593. Our results suggest that our fMRI approach could be informative for comparing effects of opioid agonists.

Female preferences for spectral call properties in the western genetic lineage of Cope's gray treefrog (Hyla chrysoscelis)

Female frogs discriminate among potential mates based on individual variation in male advertisement calls. While considerable data have accumulated allowing comparisons of female preference functions among species, we still lack fundamental knowledge about how and why the shapes of preference functions for particular call properties vary among populations within all but a few species. Here, we report results from a study aimed at describing female preference functions for spectral call properties in Cope's gray treefrog (Hyla chrysoscelis). Widespread throughout the eastern half of North America, Cope's gray treefrog is the diploid member of the cryptic diploid-tetraploid Hyla versicolor species complex, and its populations are divided into two distinct genetic lineages (eastern and western). In this study of a western lineage population, we recorded and analyzed the spectral properties of 1000 advertisement calls from 50 males and conducted two-choice phonotaxis experiments to estimate a population-level preference function. Females preferred calls with average frequencies over calls with frequencies that were 2 or 3 semitones (1.4 or 2.1 standard deviations, respectively) lower than the population mean. We observed no behavioral discrimination between calls with average and higher-than-average frequencies. Preferences discriminating against low-frequency calls were weak and were abolished by attenuating the preferred average call by 3 dB. We discuss these results in light of previous studies of eastern lineage populations, geographic variation in female preference functions, and the potential adaptive value of discriminating against calls with low frequencies.