Cardiac autonomic function in REM-related obstructive sleep apnoea: insights from nocturnal heart rate variability profiles.

PURPOSE: In light of the reported association between REM-related obstructive sleep apnoea (OSA) and heightened cardiovascular risk, this study aims to compare cardiac autonomic function in patients with REM-OSA and OSA independent of sleep stage. We hypothesized that REM-OSA patients would exhibit higher sympathetic cardiac modulation based on heart rate variability (HRV) profiles. METHODS: HRV was compared between the OSA group (AHI ≥ 5 events/h, n = 252) and the REM-OSA group (AHI ≥ 5 events/h, AHIREM:AHINREM ≥ 2, n = 137). Time- and frequency-domain measures of HRV were analysed during N2 and REM sleep. RESULTS: Clinical characteristics between the two test groups differed significantly, 45% of REM-OSA patients were female, with mild OSA (median, interquartile range (IQR)) AHI of 10 (7) events/h. Only 26% of the OSA cohort were female with moderate OSA (AHI = 17 (20) events/h, p < 0.001). Compared with the OSA group, the low frequency to high frequency ratio (LF:HF) and LF power were lower and HF power was higher in the REM-OSA group during N2 (LF:HF, p = 0.012; LF; p = 0.013; HF, p = 0.007) and in REM sleep (LF:HF, p = 0.002; LF, p = 0.004; HF, p < 0.001). Patient sex and OSA severity had a significant combined effect on average N to N interval, LF power, and LF:HF ratio during N2 and REM sleep (all p < 0.001). CONCLUSION: Contrary to our hypothesis, REM-OSA patients demonstrated consistently higher cardiac vagal modulation, reflecting better cardiac autonomic adaptation. These results were attributed to differences in OSA severity and sex in these two groups, both independently affecting HRV. This study emphasises the need for future research into the underlying pathophysiology of REM-OSA and the potential implications of sex and OSA severity on cardiovascular risk.

Heart rate variability analysis in obstructive sleep apnea patients with daytime sleepiness.

STUDY OBJECTIVES: Recent studies suggest that sleepy patients with obstructive sleep apnea (OSA) are at higher risk for incident cardiovascular disease. This study assessed cardiac autonomic function in sleepy versus non-sleepy patients with OSA using heart rate variability (HRV) analysis. We hypothesized that HRV profiles of sleepy patients would indicate higher cardiovascular risk. METHODS: Electrocardiograms (ECG) derived from polysomnograms (PSG) collected by the Sydney Sleep Biobank were used to study HRV in groups of sleepy (ESS ≥ 10) and non-sleepy OSA patients (ESS < 10). HRV parameters were averaged across available ECG signals during N2 sleep. RESULTS: A total of 421 patients were evaluated, with a mean age of 54 (14) years, body mass index of 33 (9) kg/m2, apnea-hypopnea index of 21 (28) events/h, and 66% male. The sleepy group consisted of 119 patients and the non-sleepy group 302 patients. Sleepy patients exhibited lower HRV values for: root mean square successive difference (RMSSD, p = 0.028), total power (TP, p = 0.031), absolute low frequency (LF, p = 0.045), and high-frequency (HF, p = 0.010) power compared to non-sleepy patients. Sleepy patients with moderate-to-severe OSA exhibited lower HRV values for: (RMSSD, p = 0.045; TP, p = 0.052), absolute LF (p = 0.051), and HF power (p = 0.025). There were no differences in other time and frequency domain HRV markers. CONCLUSIONS: This study shows a trend toward parasympathetic withdrawal in sleepy OSA patients, particularly in moderate-to-severe cases, lending mechanistic support to the link between the sleepy phenotype and CVD risk in OSA.

Sleep disordered breathing has minimal association with retinal microvascular diameters in a non-diabetic sleep clinic cohort.

INTRODUCTION: Obstructive sleep apnea (OSA) may increase stroke risk; retinal arteriolar (central retinal arteriolar equivalent, CRAE) diameter narrowing and/or retinal venular (central retinal venule equivalent, CRVE) widening may predict stroke. We examined relationships between sleep disordered breathing (SDB) and CRAE and CRVE and in a diabetes-free sleep clinic cohort. METHODS: Patients for SDB assessment were recruited (Main Group, n = 264, age: 58.5 ± 8.9 yrs [mean ± SD]; males: 141) for in-laboratory polysomnography (standard metrics, eg apnea hypopnea index, AHI) and retinal photographs (evening and morning). A more severe SDB sub-group (n = 85) entered a 12-month cardiovascular risk factor minimisation (hypertension/hypercholesterolemia control; RFM) and continuous positive airway pressure (CPAP) intervention (RFM/CPAP Sub-Group); successfully completed by n = 66 (AHI = 32.4 [22.1-45.3] events/hour, median[IQR]). Univariate (Spearman's correlation, t-test) and multiple linear regression models examined non-SDB and SDB associations with CRAE and CRVE measures. RESULTS: Main Group: Evening CRAE predictors were: systolic blood pressure (0.18µm decrease per mmHg, p = 0.001), age (2.47µm decrease per decade, p = 0.012), Caucasian ethnicity (4.45 µm versus non-Caucasian, p = 0.011), height (0.24 µm decrease per cm increase, p = 0.005) and smoking history (3.08 µm increase, p = 0.052). Evening CRVE predictors were: Caucasian ethnicity (11.52 µm decrease versus non-Caucasian, p>0.001), diastolic blood pressure (0.34 µm increase in CRVE per mmHg, p = 0.001), hypertension history (6.5 µm decrease, p = 0.005), and smoking history (4.6 µm increase, p = 0.034). No SDB metric (all p>0.08) predicted CRAE or CRVE measures. RFM/CPAP Sub-Group: A one-unit increase in ln(AHI+1) was associated with a 0.046µm increase in CRAE (n = 85; p = 0.029). Mean evening CRAE and CRVE values did not change across the intervention (n = 66), but evening CRVE decreased ~6.0 µm for individuals with AHI >30 events/hr. CONCLUSION: No major SDB associations with CRAE or CRVE were identified, although the RFM/CPAP intervention reduced evening CRVE for severe OSA patients. Implications for cerebro-vascular disease risk remain uncertain. TRIAL REGISTRATION: The protocol was registered with the Australian New Zealand Clinical Trials Registry (Trial Id: ACTRN12620000694910).

Retinal abnormalities, although relatively common in sleep clinic patients referred for polysomnography, are largely unrelated to sleep-disordered breathing.

STUDY OBJECTIVES: There has been long-standing interest in potential links between obstructive sleep apnea (OSA) and eye disease. This study used retinal photography to identify undiagnosed retinal abnormalities in a cohort of sleep clinic patients referred for polysomnography (PSG) and then determined associations with PSG-quantified sleep-disordered breathing (SDB) severity. METHODS: Retinal photographs (n = 396 patients) were taken of each eye prior to polysomnography and graded according to validated, standardized, grading scales. SDB was quantified via in-laboratory polysomnography (PSG; n = 385) using standard metrics. A questionnaire (n = 259) documented patient-identified pre-existing eye disease. Within-group prevalence rates were calculated on a per patient basis. Data were analyzed using multivariate logistic regression models to determine independent predictors for retinal abnormalities. P < 0.05 was considered significant. RESULTS: Main findings were (1) 76% of patients reported no pre-existing "eye problems"; (2) however, 93% of patients had at least one undiagnosed retinal photograph-identified abnormality; (3) most common abnormalities were drusen (72%) and peripapillary atrophy (PPA; 47%); (4) age was the most common risk factor; (5) diabetes history was an expected risk factor for retinopathy; (6) patients with very severe levels of SDB (apnea hypopnea index ≥ 50 events/h) were nearly three times more likely to have PPA. CONCLUSION: Retinal photography in sleep clinic settings will likely detect a range of undiagnosed retinal abnormalities, most related to patient demographics and comorbidities and, except for PPA, not associated with SDB. PPA may be indicative of glaucoma, and any association with severe SDB should be confirmed in larger prospective studies.

Hand-held fans: Physical Properties and Perceptions of Patients with COPD.

RATIONALE: Patients with chronic obstructive pulmonary disease (COPD) may remain breathless despite optimal medical treatment. Hand-held fans (HHFs) are recommended to relieve breathlessness, but little is known about physical properties of different fans and the impact HHF properties may have on patient perceptions of fans. OBJECTIVE: To describe the physical properties of HHFs and investigate the relationship of these properties to patient fan preference. METHODS: We recruited 33 participants with COPD who were attending a pulmonary rehabilitation program. Participants trialled 5 HHFs in random order. Participants rated perceived airflow, pleasantness of airflow, noisiness, and ease of use of each fan using a 1-10 numerical rating scale (NRS). After trialling all 5 fans, participants ranked each HHF from best (5 arbitrary units; a.u.) to worst (1 a.u.). Rankings for each fan were tallied to produce total HHF scores (T-HHF; maximum=165 a.u.). Objective measurements were made of sound intensity (dB; sound level meter), airflow between 5cm and 30cm from the middle of the fan (anemometer), blade rotation speed, blade size and total fan weight. We assessed the strength of association of T-HHF scores against mean NRS values using Spearman correlation coefficients and used linear regression to compare measured to perceived airflow, and noisiness to sound intensity. RESULTS: Participants were 68.5 ± 8.9 years (mean ± SD), 63% male, with a median FEV1 of 0.99L(IQR 0.76-1.31L). There was considerable variability between the 5 fans tested in terms of participant perceptions and physical properties with an almost 5-fold difference in air velocity at 30cm and a 3-fold difference in blade rotation speed. The most preferred fan had a T-HHF score of 140 and had the highest airflow (1.9 m/s) measured at 30cm. T-HHF score positively correlated with pleasantness of airflow (r = 0.46; P < 0.001), perceived airflow (r=0.58; P<0.001) and airflow velocity at 30cm from fan blades (r=1.0; P = 0.02). There were positive linear relationships between fan airflow velocity and perceived air amount, and between measured sound intensity and perceived noisiness(both P<0.001). Women reported significantly higher perceived airflow than men (P < 0.001). CONCLUSIONS: The physical properties of the five included HHFs are quite distinct. Patient preference was related to pleasantness of airflow, perceived airflow, and measured airflow at 30cm. Gender differences in perceived airflow were noted. Future research should explore the relationship between HHF characteristics and relief of breathlessness.

Maintenance of non-pharmacological strategies 6 months after patients with chronic obstructive pulmonary disease (COPD) attend a breathlessness service: a qualitative study.

OBJECTIVES: This study aimed to explore the degree to which non-pharmacological strategies for chronic breathlessness are sustained 6 months after completing a breathlessness service in patients with chronic obstructive pulmonary disease (COPD), and patient perceptions regarding the need for ongoing support. DESIGN: A qualitative approach was taken using semistructured telephone interviews. Thematic analysis used an integrative approach. SETTING: The Westmead Breathlessness Service (WBS) trains patients with COPD to self-manage chronic breathlessness over an 8-week programme with multidisciplinary input and home visits. PARTICIPANTS: Patients with moderate to very severe COPD who had completed the WBS programme 6 months earlier. RESULTS: Thirty-two participants were interviewed. One or more breathlessness self-management strategies were sustained by most participants, including breathing techniques (n=22; 69%), the hand-held fan (n=17; 53%), planning/pacing and exercise (n=14 for each; 44%) and strategic use of a four-wheeled walker (n=8; 25%). However, almost a third of participants appeared to be struggling psychologically, including some who had refused psychological intervention. A 'chaos narrative' appeared to be prevalent, and many participants had poor recall of the programme. CONCLUSIONS: Self-management strategies taught by breathlessness services to patients with moderate to very severe COPD have potential to be sustained 6 months later. However, psychological coping may be more challenging to maintain. Research is needed on ways to improve resilience to set-backs and uptake of psychological interventions, as well as to understand and address the implications of poor recall for self-management. TRIAL REGISTRATION NUMBER: ACTRN12617000499381.

Patient perspectives on how to optimise benefits from a breathlessness service for people with COPD.

This study aimed to inform understanding of how to optimise patient-perceived benefits from a breathlessness service designed for patients with moderate to very severe chronic obstructive pulmonary disease (COPD). The Westmead Breathlessness Service (WBS) trains patients to self-manage over an 8-week programme, with multidisciplinary input and home visits. A qualitative approach was taken, using semi-structured telephone interviews. Each transcript was globally rated as suggesting 'significant', 'some' or 'no' impact from WBS, and thematic analysis used an integrative approach. Forty-one consecutive participants were interviewed to reach 'information power'. Eighteen (44%) participants reported 'significant' impact, 17 (41%) 'some' impact, and two (5%) 'no' impact. Improvements to breathlessness were usually in the affective and impact dimensions but, more uncommonly, also sensory-perceptual. Participants who benefited in self-esteem, confidence and motivation attributed this to one-to-one multidisciplinary coaching and home visits. Further research should test whether including/excluding more intensive programme elements based on individual need might improve cost-effectiveness.

Protocol for a Single-Blind, Randomized, Parallel-Group Study of a Nonpharmacological Integrated Care Intervention to Reduce the Impact of Breathlessness in Patients with Chronic Obstructive Pulmonary Disease.

Background: Patients with chronic obstructive pulmonary disease (COPD) frequently experience breathlessness despite maximal medical therapy. Nonpharmacological management is effective in studies enrolling patients with a variety of respiratory diseases; however, the impact on patients with COPD is unclear. Methods: A protocol for a mixed-methods, single-center, observer-blinded, fast-track randomized-controlled, parallel-group trial comparing an immediate eight-week nonpharmacological Westmead Breathlessness Service (WBS) to a standard care control group is described. Population: At least moderate COPD (FEV1:FVC ≤0.7; FEV1%predicted ≤60%) and persistent disabling breathlessness (modified Medical Research Council ≥2). Intervention: Individualized prescription of nonpharmacological breathlessness interventions, including a handheld fan, breathing techniques, postures to relieve breathlessness, relaxation, nutritional advice, energy conservation, and exercise advice delivered by a team including doctors, nurses, a physiotherapist, an occupational therapist, a dietitian, and speech pathologist. Control: Participants who receive the WBS intervention after an eight-week period while receiving usual care (standard care group). Outcome: Primary outcome-Chronic Respiratory Questionnaire (CRQ) Mastery subscale. Secondary outcomes include numerical rating scale of breathlessness intensity, unpleasantness, and confidence managing breathlessness; quality of life as measured by other CRQ subscales; Hospital Anxiety and Depression Scale score; daily step count; health resource utilization 12 months pre- and postintervention; and cost-effectiveness. Qualitative analysis of participant interviews will provide additional context for interpreting the quantitative results. Discussion: This study aims to establish the efficacy and cost-effectiveness of an eight-week nonpharmacological breathlessness intervention in patients with COPD. Trial Registration: The Australian New Zealand Clinical Trial Registry ACTRN12617000499381 (06/04/17).

Bilateral hypoglossal nerve stimulation for treatment of adult obstructive sleep apnoea.

BACKGROUND AND AIM: Hypoglossal nerve stimulation (HNS) decreases obstructive sleep apnoea (OSA) severity via genioglossus muscle activation and decreased upper airway collapsibility. This study assessed the safety and effectiveness at 6 months post-implantation of a novel device delivering bilateral HNS via a small implanted electrode activated by a unit worn externally, to treat OSA: the Genio™ system. METHODS: This prospective, open-label, non-randomised, single-arm treatment study was conducted at eight centres in three countries (Australia, France and the UK). Primary outcomes were incidence of device-related serious adverse events and change in the apnoea-hypopnoea index (AHI). The secondary outcome was the change in the 4% oxygen desaturation index (ODI). Additional outcomes included measures of sleepiness, quality of life, snoring and device use. This trial was registered with ClinicalTrials.gov, number NCT03048604. RESULTS: 22 out of 27 implanted participants (63% male, aged 55.9±12.0 years, body mass index (BMI) 27.4±3.0 kg·m-2) completed the protocol. At 6 months BMI was unchanged (p=0.85); AHI decreased from 23.7±12.2 to 12.9±10.1 events·h-1, a mean change of 10.8 events·h-1 (p<0.001); and ODI decreased from 19.1±11.2 to 9.8±6.9 events·h-1, a mean change of 9.3 events·h-1 (p<0.001). Daytime sleepiness (Epworth Sleepiness Scale; p=0.01) and sleep-related quality of life (Functional Outcomes of Sleep Questionnaire-10; p=0.02) both improved significantly. The number of bed partners reporting loud, very intense snoring, or leaving the bedroom due to participant snoring decreased from 96% to 35%. 91% of participants reported device use >5 days per week, and 77% reported use for >5 h per night. No device-related serious adverse events occurred during the 6-month post-implantation period. CONCLUSIONS: Bilateral HNS using the Genio™ system reduces OSA severity and improves quality of life without device-related complications. The results are comparable with previously published HNS systems despite minimal implanted components and a simple stimulation algorithm.

Correction to: Objective and Subjective Effects of a Prototype Nasal Dilator Strip on Sleep in Subjects with Chronic Nocturnal Nasal Congestion.

The article "Objective and Subjective Effects of a Prototype Nasal Dilator Strip on Sleep in Subjects with Chronic Nocturnal Nasal Congestion", written by John R. Wheatley, Terence C. Amis, Sharon A. Lee, Renee Ciesla, Gilbert Shanga was originally published electronically on the publisher's internet portal (currently SpringerLink) on May, 22, 2019 without Open Access. The article has now been made Open Access.

Objective and Subjective Effects of a Prototype Nasal Dilator Strip on Sleep in Subjects with Chronic Nocturnal Nasal Congestion.

INTRODUCTION: This exploratory study characterized the performance of a nasal dilator strip with improved spring forces in lowering nasal resistance during sleep and reducing sleep-disordered breathing in subjects with difficulty sleeping due to chronic nocturnal nasal congestion. METHODS: Subjects applied the strip at bedtime for 28 days (active phase; n = 70). Objective assessments included snoring variables, breathing route during sleep, and polysomnography measures compared with baseline. Nasal breathing, congestion, and sleep were measured subjectively using rating scales and questionnaires. During a crossover nasal resistance phase (n = 55), nasal resistance was measured using posterior rhinomanometry with the strip applied on one of two nights. RESULTS: In the active phase, breathing and sleep were perceived to improve, with less daytime sleepiness (P < 0.04) and increased ease of breathing, sleep quality, staying asleep, and feeling refreshed in the morning (all P < 0.0001). However, while objective polysomnography metrics were generally similar with and without the strip, median wake after sleep onset time was numerically reduced by ~ 11 min, and the spontaneous arousal rate fell by ~ 37%. In the nasal resistance phase (n = 55), median resistance (at 0.2-0.25 l/s) while asleep was 39.1% lower with (n = 37) versus without (n = 36) the strip (1.34 vs. 2.20 cmH2O/l/s; P = 0.048). CONCLUSIONS: This exploratory study supports a role for the improved spring force nasal dilator strip in alleviating sleep-related symptoms in subjects with chronic nasal congestion, potentially via lowering nasal resistance and reducing nocturnal awakenings. A larger study is indicated to confirm these preliminary data. CLINICALTRIALS. GOV IDENTIFIER: NCT03105297. FUNDING: GlaxoSmithKline Consumer Healthcare. Plain language summary available for this article.

Pupil Dilation May Affect Retinal Vessel Caliber Measures.

PURPOSE: To assess the effect of pupil dilation on measures of retinal vessel caliber. DESIGN: Observational study with self-comparisons Methods: Retinal photographs were taken for both eyes of 25 subjects before and after pupil dilation. Three photographic graders, masked to pupil dilation status, measured the same set of images using a computer-assisted, semi-automatic method. We compared means (standard deviations) of retinal arteriolar caliber equivalent (CRAE) and retinal venular caliber equivalent (CRVE) of the same eyes between pre- and post-dilation images. We assessed concordance correlation coefficients (CC), Bland Altman limits-of-agreements, and used linear mixed models to assess CRAE and CRVE measures associated with pupil dilation (influencing image quality), graders (observers) and right-left eye variation. RESULTS: We found high CCs for CRAE (0.82-0.94) and CRVE (0.87-0.94) between pre- and post-dilation images of the same eyes across the graders. Bland Altman plots showed that mean differences ranged from 0.55-3.42µm for CRAE and 1.56-2.29µm for CRVE. After adjusting for right-left eye random variation, a significant fixed effect of dilation was evident in mean CRAE in two of the three graders. There was no significant fixed effect of dilation in mean CRVE across all graders. In models including data of both eyes' measures from pre- and post-dilation images by three graders, the fixed effect for dilation status contributed significantly to CRAE and CRVE variances whereas random effects for graders and dilation status contributed minimally. CONCLUSIONS: Contrary to our hypothesis, we found a systematic effect of pupil dilation on retinal vessel caliber measures.

Magnitude of exercise capacity and quality of life improvement following repeat pulmonary rehabilitation in patients with COPD.

BACKGROUND: Maintenance and repeated pulmonary rehabilitation programs (PRPs) for patients with COPD have attempted to prolong PRP benefits beyond 12-24 months. However, there is limited evidence as to the magnitude of benefit or the ideal interval between repeating the program under "real-world" conditions in which patients are referred based on clinical necessity. Therefore, we reviewed the effects of repeating PRP in a physician-referred cohort of patients with COPD. METHODS: A total of 141 individuals with COPD completed PRP twice and 35 completed PRP three times over a 12-year period. We used linear mixed-effects models to quantify the magnitude and change in 6-minute walk distance (6MWD), St George's Respiratory Questionnaire (SGRQ), and Hospital Anxiety and Depression Scale (HADS) for each PRP. One-way analysis of variance with Tukey's post hoc analysis compared the effects of different time intervals on 6MWD, SGRQ, and HADS between PRPs. RESULTS: Despite 39 mL/year average decrease in forced expiratory volume in 1 second, overall 6MWD improved following each PRP (PRP1=58 m, P<0.0001; PRP2=42 m, P<0.0001; PRP3=32 m, P<0.003). Mean SGRQ decreased after PRP1 (-7.0 units; P<0.001) and PRP2 (-4.9 units; P<0.0001) but not after PRP3 (-3.2 units; P=0.10). HADS decreased after PRP1 (-1.9 units; P<0.0001) and PRP2 (-1.7 units; P=0.0001) but not after PRP3 (-0.4 units; P=0.63). CONCLUSION: In physician-referred patients who underwent repeat PRP as clinically required, there were clear benefits in functional exercise capacity following each repeat PRP, which was not affected by the time interval between PRPs. Health-related quality of life and mood improved after the first two PRPs, but not after a third.

Are there vocal cues to human developmental stability? Relationships between facial fluctuating asymmetry and voice attractiveness.

Fluctuating asymmetry (FA), deviation from perfect bilateral symmetry, is thought to reflect an organism's relative inability to maintain stable morphological development in the face of environmental and genetic stressors. Previous research has documented negative relationships between FA and attractiveness judgments in humans, but scant research has explored relationships between the human voice and this putative marker of genetic quality in either sex. Only one study (and in women only) has explored relationships between vocal attractiveness and asymmetry of the face, a feature-rich trait space central in prior work on human genetic quality and mate choice. We therefore examined this relationship in three studies comprising 231 men and 240 women from two Western samples as well as Hadza hunter-gatherers of Tanzania. Voice recordings were collected and rated for attractiveness, and FA was computed from two-dimensional facial images as well as, for a subset of men, three-dimensional facial scans. Through meta-analysis of our results and those of prior studies, we found a negative association between FA and vocal attractiveness that was highly robust and statistically significant whether we included effect sizes from previously published work, or only those from the present research, and regardless of the inclusion of any individual sample or method of assessing FA (e.g., facial or limb FA). Weighted mean correlations between FA and vocal attractiveness across studies were -.23 for men and -.29 for women. This research thus offers strong support for the hypothesis that voices provide cues to genetic quality in humans.

Sexual selection on male vocal fundamental frequency in humans and other anthropoids.

In many primates, including humans, the vocalizations of males and females differ dramatically, with male vocalizations and vocal anatomy often seeming to exaggerate apparent body size. These traits may be favoured by sexual selection because low-frequency male vocalizations intimidate rivals and/or attract females, but this hypothesis has not been systematically tested across primates, nor is it clear why competitors and potential mates should attend to vocalization frequencies. Here we show across anthropoids that sexual dimorphism in fundamental frequency (F0) increased during evolutionary transitions towards polygyny, and decreased during transitions towards monogamy. Surprisingly, humans exhibit greater F0 sexual dimorphism than any other ape. We also show that low-F0 vocalizations predict perceptions of men's dominance and attractiveness, and predict hormone profiles (low cortisol and high testosterone) related to immune function. These results suggest that low male F0 signals condition to competitors and mates, and evolved in male anthropoids in response to the intensity of mating competition.

Development and validation of a computational finite element model of the rabbit upper airway: simulations of mandibular advancement and tracheal displacement.

The mechanisms leading to upper airway (UA) collapse during sleep are complex and poorly understood. We previously developed an anesthetized rabbit model for studying UA physiology. On the basis of this body of physiological data, we aimed to develop and validate a two-dimensional (2D) computational finite element model (FEM) of the passive rabbit UA and peripharyngeal tissues. Model geometry was reconstructed from a midsagittal computed tomographic image of a representative New Zealand White rabbit, which included major soft (tongue, soft palate, constrictor muscles), cartilaginous (epiglottis, thyroid cartilage), and bony pharyngeal tissues (mandible, hard palate, hyoid bone). Other UA muscles were modeled as linear elastic connections. Initial boundary and contact definitions were defined from anatomy and material properties derived from the literature. Model parameters were optimized to physiological data sets associated with mandibular advancement (MA) and caudal tracheal displacement (TD), including hyoid displacement, which featured with both applied loads. The model was then validated against independent data sets involving combined MA and TD. Model outputs included UA lumen geometry, peripharyngeal tissue displacement, and stress and strain distributions. Simulated MA and TD resulted in UA enlargement and nonuniform increases in tissue displacement, and stress and strain. Model predictions closely agreed with experimental data for individually applied MA, TD, and their combination. We have developed and validated an FEM of the rabbit UA that predicts UA geometry and peripharyngeal tissue mechanical changes associated with interventions known to improve UA patency. The model has the potential to advance our understanding of UA physiology and peripharyngeal tissue mechanics.

The face of female dominance: Women with dominant faces have lower cortisol.

The human face displays a wealth of information, including information about dominance and fecundity. Dominance and fecundity are also associated with lower concentrations of the stress hormone cortisol, suggesting that cortisol may negatively predict facial dominance and attractiveness. We digitally photographed 61 women's faces, had these images rated by men and women for dominance, attractiveness, and femininity, and explored relationships between these perceptions and women's salivary cortisol concentrations. In a first study, we found that women with more dominant-appearing, but not more attractive, faces had lower cortisol levels. These associations were not due to age, ethnicity, time since waking, testosterone, or its interaction with cortisol. In a second study, composite images of women with low cortisol were perceived as more dominant than those of women with high cortisol significantly more often than chance by two samples of viewers, with a similar but non-significant trend in a third sample. However, data on perceptions of attractiveness were mixed; low-cortisol images were viewed as more attractive by two samples of US viewers and as less attractive by a sample of Mexican viewers. Our results suggest that having a more dominant-appearing face may be associated with lower stress and hence lower cortisol in women, and provide further evidence regarding the information content of the human face.

Fulfilling desire: evidence for negative feedback between men's testosterone, sociosexual psychology, and sexual partner number.

Across human societies and many nonhuman animals, males have greater interest in uncommitted sex (more unrestricted sociosexuality) than do females. Testosterone shows positive associations with male-typical sociosexual behavior in nonhuman animals. Yet, it remains unclear whether the human sex difference in sociosexual psychology (attitudes and desires) is mediated by testosterone, whether any relationships between testosterone and sociosexuality differ between men and women, and what the nature of these possible relationships might be. In studies to resolve these questions, we examined relationships between salivary testosterone concentrations and sociosexual psychology and behavior in men and women. We measured testosterone in all men in our sample, but only in those women taking oral contraception (OC-using women) in order to reduce the influence of ovulatory cycle variation in ovarian hormone production. We found that OC-using women did not differ from normally-ovulating women in sociosexual psychology or behavior, but that circulating testosterone mediated the sex difference in human sociosexuality and predicted sociosexual psychology in men but not OC-using women. Moreover, when sociosexual psychology was controlled, men's sociosexual behavior (number of sexual partners) was negatively related to testosterone, suggesting that testosterone drives sociosexual psychology in men and is inhibited when those desires are fulfilled. This more complex relationship between androgens and male sexuality may reconcile some conflicting prior reports.

Pharyngeal mucosal wall folds in subjects with obstructive sleep apnea.

Mechanical processes underlying pharyngeal closure have not been examined. We hypothesized that the pharyngeal mucosal surface would fold during closure, and lowering the upper airway lining liquid surface tension would unfold areas of mucosal apposition, i.e., folds. We compared baseline pharyngeal fold numbers and response to reduction in upper airway liquid surface tension in healthy and obstructive sleep apnea (OSA) subjects. Awake, gated magnetic resonance pharyngeal airway images of 10 healthy and 11 OSA subjects were acquired before and after exogenous surfactant administration (beractant). Upper airway liquid surface tension was measured at the beginning and end of image acquisition and averaged. Velopharyngeal and oropharyngeal images were segmented and analyzed separately for average cross-sectional area, circumference, and fold number. Compared with healthy subjects, at baseline, velopharynx for OSA subjects had a smaller cross-sectional area (98.3 ± 32.5 mm(2) healthy, 52.3 ± 23.6 mm(2) OSA) and circumference (46.5 ± 8.1 mm healthy, 30.8 ± 6.1 mm OSA; both P < 0.05, unpaired t-test), and fewer folds (4.9 ± 1.6 healthy, 3.1 ± 1.8 OSA, P < 0.03). There were no differences in oropharynx for cross-sectional area, circumference, or folds. Reduction in upper airway liquid surface tension from 61.3 ± 1.2 to 55.3 ± 1.5 mN/m (P < 0.0001) did not change cross-sectional area or circumference for velopharynx or oropharynx in either group; however, in OSA subjects, oropharyngeal folds fell from 6.8 ± 3.1 to 4.7 ± 1.2 (n = 8, P < 0.05), and velopharyngeal folds from 3.3 ± 1.9 to 2.3 ± 1.2 (P = 0.08), and were unchanged in healthy subjects. Subjects with OSA have fewer velopharyngeal wall folds, which decrease further when surface tension falls. We speculate that reduced pharyngeal wall folds contribute to an increase in pharyngeal collapsibility.