Achieving Better Understanding of Obstructive Sleep Apnea Treatment Effects on Cardiovascular Disease Outcomes through Machine Learning Approaches: A Narrative Review

Obstructive sleep apnea (OSA) affects almost a billion people worldwide and is associated with a myriad of adverse health outcomes. Among the most prevalent and morbid are cardiovascular diseases (CVDs). Nonetheless, randomized controlled trials (RCTs) of OSA treatment have failed to show improvements in CVD outcomes. A major limitation in our field is the lack of precision in defining OSA and specifically subgroups with the potential to benefit from therapy. Further, this has called into question the validity of using the time-honored apnea-hypopnea index as the ultimate defining criteria for OSA. Recent applications of advanced statistical methods and machine learning have brought to light a variety of OSA endotypes and phenotypes. These methods also provide an opportunity to understand the interaction between OSA and comorbid diseases for better CVD risk stratification. Lastly, machine learning and specifically heterogeneous treatment effects modeling can help uncover subgroups with differential outcomes after treatment initiation. In an era of data sharing and big data, these techniques will be at the forefront of OSA research. Advanced data science methods, such as machine-learning analyses and artificial intelligence, will improve our ability to determine the unique influence of OSA on CVD outcomes and ultimately allow us to better determine precision medicine approaches in OSA patients for CVD risk reduction. In this narrative review, we will highlight how team science via machine learning and artificial intelligence applied to existing clinical data, polysomnography, proteomics, and imaging can do just that.

Metabolomic profiles of sleep-disordered breathing are associated with hypertension and diabetes mellitus development

Sleep-disordered breathing (SDB) is a prevalent disorder characterized by recurrent episodic upper airway obstruction. Using data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), we apply principal component analysis (PCA) to seven SDB-related measures. We estimate the associations of the top two SDB PCs with serum levels of 617 metabolites, in both single-metabolite analysis, and a joint penalized regression analysis. The discovery analysis includes 3299 individuals, with validation in a separate dataset of 1522 individuals. Five metabolite associations with SDB PCs are discovered and replicated. SDB PC1, characterized by frequent respiratory events common in older and male adults, is associated with pregnanolone and progesterone-related sulfated metabolites. SDB PC2, characterized by short respiratory event length and self-reported restless sleep, enriched in young adults, is associated with sphingomyelins. Metabolite risk scores (MRSs), representing metabolite signatures associated with the two SDB PCs, are associated with 6-year incident hypertension and diabetes. These MRSs have the potential to serve as biomarkers for SDB, guiding risk stratification and treatment decisions.

Heterogeneous Effects of CPAP in Non-Sleepy OSA on CVD Outcomes: Post-hoc Machine Learning Analysis of the ISAACC Trial (ECSACT Study)

RATIONALE

Randomized controlled trials of continuous positive airway pressure (CPAP) therapy for cardiovascular disease (CVD) prevention among patients with obstructive sleep apnea (OSA) have been largely neutral. However, given OSA is a heterogeneous disease, there may be unidentified subgroups demonstrating differential treatment effects.

OBJECTIVES

Apply a novel data-drive approach to identify non-sleepy OSA subgroups with heterogeneous effects of CPAP on CVD outcomes within the ISAACC study.

METHODS

Participants were randomly partitioned into two datasets. One for training (70%) our machine learning model and a second (30%) for validation of significant findings. Model-based recursive partitioning was applied to identify subgroups with heterogeneous treatment effects. Survival analysis was conducted to compare treatment (CPAP versus usual care [UC]) outcomes within subgroups.

RESULTS

A total of 1,224 non-sleepy OSA participants were included. Of fifty-five features entered into our model only two appeared in the final model (i.e., average OSA event duration and hypercholesterolemia). Among participants at or below the model-derived average event duration threshold (19.5 seconds), CPAP was protective for a composite of CVD events (training Hazard Ratio [HR] 0.46, p=0.002). For those with longer event duration (>19.5 seconds), an additional split occurred by hypercholesterolemia status. Among participants with longer event duration and hypercholesterolemia, CPAP resulted in more CVD events compared to UC (training HR 2.24, p=0.011). The point estimate for this harmful signal was also replicated in the testing dataset (HR 1.83, p=0.118).

CONCLUSIONS

We discovered subgroups of non-sleepy OSA participants within the ISAACC study with heterogeneous effects of CPAP. Among the training dataset, those with longer OSA event duration and hypercholesterolemia had nearly 2.5-times more CVD events with CPAP compared to UC, while those with shorter OSA event duration had roughly half the rate of CVD events if randomized to CPAP.

Advanced Proteomics and Cluster Analysis for Identifying Novel Obstructive Sleep Apnea Subtypes before and after Continuous Positive Airway Pressure Therapy

Rationale: Studies have shown elevated inflammatory biomarkers in obstructive sleep apnea (OSA), but data after continuous positive airway pressure (CPAP) treatment are inconsistent. Objectives: We used the Olink proteomics panel to identify unique OSA clusters on the basis of inflammatory protein expression and assess the impact of CPAP therapy. Methods: Adults with newly diagnosed OSA had blood drawn at baseline and three to four months after CPAP. Samples were analyzed using the Olink proteomics platform, which measures 92 prespecified inflammatory proteins using proximity extension assay. Linear mixed-effects models were used to model changes in protein expression during the period of CPAP use, adjusting for batch, age, and sex. Unsupervised hierarchical clustering was performed to identify unique inflammatory OSA clusters on the basis of inflammatory biomarkers. Within-cluster impact of CPAP on inflammatory protein expression was assessed. Results: Among 46 patients, the mean age was 46 ± 12 years (22% women), mean body mass index was 31 ± 5 kg/m2, and mean respiratory disturbance index was 33 ± 17 events/hour. Unsupervised cluster and heatmap analysis revealed three unique proteomic clusters, with low (n = 21), intermediate (n = 19), and high (n = 6) inflammatory protein expression. After CPAP, there were significant within-cluster differences in protein expression. The low inflammatory cluster had a significant increase in protein expression (16%; P = 0.02), and the high inflammatory cluster had a significant decrease in protein expression (-20%; P = 0.003), more significant among those compliant with CPAP in the low (25%; P = 0.04) and high (-22%; P = 0.01) clusters. Conclusions: We identified three unique inflammatory clusters in patients with OSA using plasma proteomics, with a differential response to CPAP by cluster. Our results are hypothesis generating and require further investigation in larger longitudinal studies for enhanced cardiovascular risk profiling in OSA.

Pharyngeal Inflammation on Positron Emission Tomography/Magnetic Resonance Imaging Before and After Obstructive Sleep Apnea Treatment

Rationale: There is upper airway inflammation in patients with obstructive sleep apnea (OSA), which reduces with continuous positive airway pressure (CPAP) therapy. Objectives: Validate the use of positron emission tomography (PET)/magnetic resonance imaging (MRI) to quantify metabolic activity within the pharyngeal mucosa of patients with OSA against nasal lavage proteomics and assess the impact of CPAP therapy. Methods: Adults with OSA underwent [18F]-Fluoro-2-deoxy-D-glucose PET/MRI of the neck before and 3 months after initiating CPAP. Nasal lavage samples were collected. Inflammatory protein expression from samples was analyzed using the Olink platform. Upper airway imaging segmentation was performed. Target-to-background ratio (TBRmax) was calculated from target pharyngeal maximum standard uptake values (SUV) and personalized background mean SUV. Most-diseased segment TBRmax was identified per participant at locations with the highest PET avidity. Correlation analysis was performed between baseline TBRmax and nasal lavage proteomics. TBRmax was compared before and after CPAP using linear mixed-effect models. Results: Among 38 participants, the baseline mean age was 46.3 years (standard deviation [SD], 12.5), 21% were female, the mean body mass index was 30.9 kg/m2 (SD, 4.6), and the mean respiratory disturbance index measured by peripheral arterial tonometry was 31 events/h (SD, 16.4). There was a significant positive correlation between pharyngeal mucosa most-diseased segment TBRmax and nasal lavage proteomic inflammation (r = 0.41 [P < 0.001, false discovery rate = 0.002]). Primary analysis revealed a reduction in the most-diseased segment TBRmax after a median of 2.91 months of CPAP therapy (-0.86 [standard error (SE) ± 0.30; P = 0.007]). Stratified analysis by smoking status revealed a significantly decreased most-diseased segment TBRmax after CPAP therapy among never-smokers but not among ever-smokers (-1.01 [SE ± 0.39; P = 0.015] vs. -0.64 [SE ± 0.49; P = 0.201]). Conclusions: CPAP therapy reduces metabolic activity measured by PET/MRI within the upper airway of adults with OSA. Furthermore, PET/MRI measures of upper airway metabolic activity correlate with a noninvasive marker of inflammation (i.e., nasal lavage inflammatory protein expression).

Sleep Irregularity and Subclinical Markers of Cardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis

Background Sleep irregularity has been linked to incident cardiovascular disease. Less is known about associations of sleep regularity with atherosclerosis. We examined cross-sectional associations of actigraphy-assessed sleep duration and sleep timing regularity with subclinical atherosclerosis in the community-based MESA (Multi-Ethnic Study of Atherosclerosis). Methods and Results MESA Sleep Ancillary Study participants (N=2032; mean age, 68.6±9.2 years; 37.9% White) completed 7-day wrist actigraphy. Participants underwent assessments of coronary artery calcium, carotid plaque presence, carotid intima-media thickness, and the ankle-brachial index. Sleep regularity was quantified by the 7-day with-in person SD of sleep duration and sleep onset timing. Relative risk regression models were used to calculate prevalence ratios and 95% CIs. Models are adjusted for demographics, cardiovascular disease risk factors, and other objectively assessed sleep characteristics including obstructive sleep apnea, sleep duration, and sleep fragmentation. After adjustment, compared with participants with more regular sleep durations (SD ≤60 minutes), participants with greater sleep duration irregularity (SD >120 minutes) were more likely to have high coronary artery calcium burden (>300; prevalence ratio, 1.33 [95% CI, 1.03-1.71]) and abnormal ankle-brachial index (<0.9; prevalence ratio, 1.75 [95% CI, 1.03-2.95]). Compared with participants with more regular sleep timing (SD ≤30 minutes), participants with irregular sleep timing (SD >90 minutes) were more likely to have high coronary artery calcium burden (prevalence ratio, 1.39 [95% CI, 1.07-1.82]). Associations persisted after adjustment for cardiovascular disease risk factors and average sleep duration, obstructive sleep apnea, and sleep fragmentation. Conclusions Sleep irregularity, particularly sleep duration irregularity, was associated with several measures of subclinical atherosclerosis. Sleep regularity may be a modifiable target for reducing atherosclerosis risk. Future investigation into cardiovascular risk reduction interventions targeting sleep irregularity may be warranted.

Sleep calibrates atherosclerotic cardiovascular disease

Sleep modulates cardiovascular health, and recent studies have begun to uncover underlying mechanistic links. An integrated translational approach that combines animal models and human trials will enrich scientific discovery, improve therapy, and help to alleviate the global burden of insufficient sleep and cardiovascular disease.

Community based assessment on Knowledge, Attitude and Practices (KAP), Risk Factors and One Health Perspective of Brucellosis in rural and urban settings of Pakistan: A Cross-Sectional Study

Bovine brucellosis is an endemic zoonotic infection of ruminants in Pakistan with detrimental impacts on livestock economy. The major losses caused by brucellosis in animals include abortions, week calves, infertility, and reduced milk production. Regardless of the prevalence of the disease, limited data is available about brucellosis in Pakistan. The present study aimed to access the one health concept in prospective of Brucellosis among small-scale dairy farmers by examining knowledge, attitude and practices at the farms and household level that might pose a risk for humans contracting brucellosis. A community-based cross-sectional survey was conducted among small household dairy farms (n=333) in rural and urban areas of district Rawalpindi and Islamabad. The results revealed almost 74.17% of the participants knew about animal brucellosis and about 69.97% of the participants were able to identify the symptoms of animal brucellosis. 58.26% of participants showed knowledge about the transmission of disease from animals to humans. A majority (70.87%) of participants used the raw milk for making other dairy products. Most household farmers are unaware of routes of transmission and major risk factors of brucellosis. Almost all the participants, except veterinarians, including butchers, dairy farm owners and workers, slaughterhouse owners and workers and farmers were involved in at least one risky practice. The moderate knowledge and poor understanding of the disease emphasize the need to initiate awareness programs to educate the farmers who are at high risk along with the improvement of vaccination programs for animals and strict implementation of brucellosis eradication policy which should be devised by government.

Pathway-Specific Polygenic Risk Scores Identify Obstructive Sleep Apnea-Related Pathways Differentially Moderating Genetic Susceptibility to Coronary Artery Disease

BACKGROUND

Obstructive sleep apnea (OSA) and its features, such as chronic intermittent hypoxia, may differentially affect specific molecular pathways and processes in the pathogenesis of coronary artery disease (CAD) and influence the subsequent risk and severity of CAD events. In particular, competing adverse (eg, inflammatory) and protective (eg, increased coronary collateral blood flow) mechanisms may operate, but remain poorly understood. We hypothesize that common genetic variation in selected molecular pathways influences the likelihood of CAD events differently in individuals with and without OSA, in a pathway-dependent manner.

METHODS

We selected a cross-sectional sample of 471 877 participants from the UK Biobank, with 4974 ascertained to have OSA, 25 988 to have CAD, and 711 to have both. We calculated pathway-specific polygenic risk scores for CAD, based on 6.6 million common variants evaluated in the CARDIoGRAMplusC4D genome-wide association study (Coronary ARtery DIsease Genome wide Replication and Meta-analysis [CARDIoGRAM] plus The Coronary Artery Disease [C4D] Genetics), annotated to specific genes and pathways using functional genomics databases. Based on prior evidence of involvement with intermittent hypoxia and CAD, we tested pathway-specific polygenic risk scores for the HIF1 (hypoxia-inducible factor 1), VEGF (vascular endothelial growth factor), NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) and TNF (tumor necrosis factor) signaling pathways.

RESULTS

In a multivariable-adjusted logistic generalized additive model, elevated pathway-specific polygenic risk scores for the Kyoto Encyclopedia of Genes and Genomes VEGF pathway (39 genes) associated with protection for CAD in OSA (interaction odds ratio 0.86, P=6×10-4). By contrast, the genome-wide CAD PRS did not show evidence of statistical interaction with OSA.

CONCLUSIONS

We find evidence that pathway-specific genetic risk of CAD differs between individuals with and without OSA in a qualitatively pathway-dependent manner. These results provide evidence that gene-by-environment interaction influences CAD risk in certain pathways among people with OSA, an effect that is not well-captured by the genome-wide PRS. This invites further study of how OSA interacts with genetic risk at the molecular level and suggests eventual personalization of OSA treatment to reduce CAD risk according to individual pathway-specific genetic risk profiles.

Traditional knowledge about medicinal plant in the remote areas of Wari Tehsil, Dir Upper, Pakistan

Traditional medicine is cheaper and easily available to local people, to care for most frequent diseases in the Northern parts of Pakistan. Our study aimed at inventorying medicine from local plants, documenting their uses, and assessing their market value in 2015-2018 during spring, summer, and winter seasons. A total of 15 trips were made, 5 in each season. Semi-structured interviews with 165 inhabitant's age range between 20-80 years were conducted, analyzed the data is analyzed using Relative frequency of citation(RFC), Use Value(UV), Fidelity Level(FL), Informants consensus factor(ICF), and Jaccard index(JI) to find the most frequent and well-known used species in the area. A total of 86 species belonging to 39 vascular plant families, 33 genera were documented as medicinally important. Family Asteraceae was observed as the dominant family among all the families with 10 species, the leaf was the most used parts and decoction 36% was the most preferred preparation type. Herb was the predominant life form (67%). The maximum UV (0.92) was demonstrated by J. adhatoda L. species, while A. sativum L. shows maximum RFC (0.58), the highest ICF value represented by diarrhea and dermatitis 0.92, and high FL value is recorded 100%. According to our collections, wild species were 45%, invasive species were 38% and cultivated 17% recorded, dicots species were recorded more 81%. Seven 7 medicinal species is being economically important and export to the local and international market of the world, whereas P. integrima L. species were the most exported species according to the local dealers. The investigated area is rural and the local people depend on the area's plants for their health needs, and other uses like a vegetable, fuelwood, fodder, etc. The current result of RFC, UV, ICF, FL, and JI shows that medicinal flora needs to be pharmacologically and phytochemically investigated to prove their efficacy. The documentation of medicinal knowledge is important to preserve this precious old knowledge before it is lost forever, due to technological and environmental changes in the world.

Whole-genome association analyses of sleep-disordered breathing phenotypes in the NHLBI TOPMed program

BACKGROUND

Sleep-disordered breathing is a common disorder associated with significant morbidity. The genetic architecture of sleep-disordered breathing remains poorly understood. Through the NHLBI Trans-Omics for Precision Medicine (TOPMed) program, we performed the first whole-genome sequence analysis of sleep-disordered breathing.

METHODS

The study sample was comprised of 7988 individuals of diverse ancestry. Common-variant and pathway analyses included an additional 13,257 individuals. We examined five complementary traits describing different aspects of sleep-disordered breathing: the apnea-hypopnea index, average oxyhemoglobin desaturation per event, average and minimum oxyhemoglobin saturation across the sleep episode, and the percentage of sleep with oxyhemoglobin saturation < 90%. We adjusted for age, sex, BMI, study, and family structure using MMSKAT and EMMAX mixed linear model approaches. Additional bioinformatics analyses were performed with MetaXcan, GIGSEA, and ReMap.

RESULTS

We identified a multi-ethnic set-based rare-variant association (p = 3.48 × 10-8) on chromosome X with ARMCX3. Additional rare-variant associations include ARMCX3-AS1, MRPS33, and C16orf90. Novel common-variant loci were identified in the NRG1 and SLC45A2 regions, and previously associated loci in the IL18RAP and ATP2B4 regions were associated with novel phenotypes. Transcription factor binding site enrichment identified associations with genes implicated with respiratory and craniofacial traits. Additional analyses identified significantly associated pathways.

CONCLUSIONS

We have identified the first gene-based rare-variant associations with objectively measured sleep-disordered breathing traits. Our results increase the understanding of the genetic architecture of sleep-disordered breathing and highlight associations in genes that modulate lung development, inflammation, respiratory rhythmogenesis, and HIF1A-mediated hypoxic response.

Novel non-invasive assessment of upper airway inflammation in obstructive sleep apnea using positron emission tomography/magnetic resonance imaging

PURPOSE

To develop a novel non-invasive technique to quantify upper airway inflammation using positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with obstructive sleep apnea (OSA).

METHODS

Patients with treatment naïve moderate-to-severe OSA underwent [18F]-fluoro-2-deoxy-D-glucose (FDG) PET/MRI. Three readers independently performed tracings of the pharyngeal soft tissue on MRI. Standardized uptake values (SUV) were generated from region of interest (ROI) tracings on corresponding PET images. Background SUV was measured from the sternocleidomastoid muscle. SUV and target-to-background (TBR) were compared across readers using intraclass correlation coefficient (ICC) analyses. SUV from individual image slices were compared between each reader using Bland-Altman plots and Pearson correlation coefficients. All tracings were repeated by one reader for assessment of intra-reader reliability.

RESULTS

Five participants completed our imaging protocol and analysis. Median age, body mass index, and apnea-hypopnea index were 41 years (IQR 40.5-68.5), 32.7 kg/m² (IQR 28.1-38.1), and 30.7 event per hour (IQR 19.5-48.1), respectively. The highest metabolic activity regions were consistently localized to palatine or lingual tonsil adjacent mucosa. Twenty-five ICC met criteria for excellent agreement. The remaining three were TBR measurements which met criteria for good agreement. Head-to-head comparisons revealed strong correlation between each reader.

CONCLUSIONS

Our novel imaging technique demonstrated reliable quantification of upper airway FDG avidity. This technology has implications for future work exploring local airway inflammation in individuals with OSA and exposure to pollutants. It may also serve as an assessment tool for response to OSA therapies.

Sleep-disordered breathing and left ventricular scar on cardiac magnetic resonance: results of the Multi-Ethnic Study of Atherosclerosis

STUDY OBJECTIVES

The objectives of this study were to evaluate the independent association between sleep-disordered breathing (SDB) using overnight polysomnography and left ventricular (LV) scar using cardiac magnetic resonance (CMR) with late-gadolinium enhancement in a community-based cohort of the Multi-Ethnic Study of Atherosclerosis.

METHODS

Our analytical sample includes 934 participants from the fifth examination of the Multiethnic Study of Atherosclerosis who underwent both polysomnography and CMR. SDB was categorized as follows: no-SDB (apnea-hypopnea index [AHI] < 5 events/h), mild SDB (5 events/h ≤ AHI < 15 events/h), and moderate-severe SDB (AHI ≥ 15 events/h). LV scar was considered present if there was presence of scar on CMR (late-gadolinium enhancement > 0%). Logistic regression with multivariable adjustment for confounders (age, sex, race/ethnicity, body mass index, and cardiometabolic risk factors) was used to examine the independent association of SDB with LV scar. Confounders were identified using directed acyclic graphs.

RESULTS

The mean age of our sample was 67.0 ± 8.5 years (SD), with 49% (n = 461) females and a prevalence of SDB (AHI ≥ 5 events/h) of 63% (n = 590). LV scar was more prevalent in individuals with SDB (9.5%) versus those without SDB (3.8%; P < .01), and 88% of all LV scars were clinically unrecognized. After multivariable adjustment, both mild SDB and moderate-severe SDB were independently associated with LV scar (odds ratio, 2.53; 95% confidence interval, 1.13-5.64 and odds ratio, 2.31; 95% confidence interval, 1.01-5.24, respectively).

CONCLUSIONS

In a community-based cohort, SDB (including mild) is independently associated with a more than 2-fold increase in the odds of LV scar presence measured using CMR with late-gadolinium enhancement. Most LV scars were clinically unrecognized. The impact of SDB treatment on subclinical myocardial infarction needs to be investigated in future studies.

Sleep apnea, coronary artery calcium density and cardiovascular events: results from the Multi-Ethnic Study of Atherosclerosis (MESA)

STUDY OBJECTIVES

Evaluate the association between obstructive sleep apnea (OSA), coronary artery calcium (CAC) density, and cardiovascular events in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

We analyzed 1041 participants with non-zero CAC scores who had polysomnography and CAC density data from the fifth examination of MESA. OSA was defined as apnea-hypopnea index [AHI] ≥ 15 events/hour. Multivariable linear regression models were used to evaluate the independent association between OSA and CAC density. Additionally, we evaluated the impact of OSA on associations of CAC measures with incident CVD events by testing for interaction in Cox proportional hazard regression models.

RESULTS

Our analytical sample was 45% female with a mean age of 70.6 +/- 9 years. Of this sample, 36.7% (n=383/1041) had OSA (AHI≥15). OSA was inversely and weakly associated with CAC density (β= -0.09, 95% CI -0.17 to -0.02, p=0.014) and remained significantly associated after controlling for traditional cardiovascular risk factors (β= -0.08, 95% CI -0.16 to 0, p=0.043). However, this inverse association was attenuated after controlling for BMI (β=-0.05, 95% CI -0.13 to 0.02, p=0.174). The mean follow-up period for CVD events was 13.3 +/- 2.8 years. Additionally, exploratory analysis demonstrated that CAC density was independently and inversely associated with CVD events only in the non-OSA subgroup (AHI≤15) (HR 0.509 [CI 0.323 - 0.801], p=0.0035).

CONCLUSIONS

OSA was associated with lower CAC density, but this association was attenuated by BMI. Further, increased CAC density was associated with a reduced risk of CVD events only in individuals within the non-OSA group in exploratory analysis.

Self-reported sleep duration is associated with time in work physical activity but not transportation or leisure physical activity among Hispanic/Latino adults in the U.S.: results from the Hispanic Community Health Study/Study of Latinos

OBJECTIVES

The objective of this study is to test the hypothesis that short sleep duration is associated with fewer minutes of transportation, work, and leisure physical activity (PA).

DESIGN

This is a cross-sectional study conducted from 2008 to 2011.

SETTING

The study setting included four sites across the U.S. (Bronx, NY; Chicago, IL; Miami, FL; San Diego, CA).

PARTICIPANTS

A total of 14,653 Hispanic/Latino adults aged 18-74 years were enrolled as participants for the study.

MEASUREMENTS

Respondents reported sleep duration and transportation (including walking and cycling), work (including volunteering, paid work, and household chores), and leisure (including sports) PA domains and sociodemographic characteristics, other sleep characteristics, cardiometabolic health, health behaviors, and depressive symptoms.

RESULTS

In analyses weighted to reflect the Hispanic/Latino population of the four cities sampled, 61% had sleep duration 7-9 hours, 19% each had sleep duration < 7 hours and > 9 hours. Those sleeping < 7 hours spent 106 minutes/day in work-related PA, compared with those who spent fewer than 40 minutes/day in transportation-related or leisure-related PA. Sleep duration < 7 hours was associated with 26 minutes more in work-related PA (95% confidence interval [CI]: 16.7, 36.0), compared with sleep duration of 7-9 hours, adjusting for age and sex. Results were similar in employed respondents only, adjusting for occupation class and shift work frequency. Sleep duration was not associated with transportation-related or leisure-related PA.

CONCLUSIONS

Short sleep duration is associated with more work-related PA, both in the overall sample and among those employed. Individuals with higher work-related PA may face multiple demands and stressors that negatively influence sleep duration.

Admixture mapping identifies novel loci for obstructive sleep apnea in Hispanic/Latino Americans

Obstructive sleep apnea (OSA) is a common disorder associated with increased risk of cardiovascular disease and mortality. Its prevalence and severity vary across ancestral background. Although OSA traits are heritable, few genetic associations have been identified. To identify genetic regions associated with OSA and improve statistical power, we applied admixture mapping on three primary OSA traits [the apnea hypopnea index (AHI), overnight average oxyhemoglobin saturation (SaO2) and percentage time SaO2 < 90%] and a secondary trait (respiratory event duration) in a Hispanic/Latino American population study of 11 575 individuals with significant variation in ancestral background. Linear mixed models were performed using previously inferred African, European and Amerindian local genetic ancestry markers. Global African ancestry was associated with a lower AHI, higher SaO2 and shorter event duration. Admixture mapping analysis of the primary OSA traits identified local African ancestry at the chromosomal region 2q37 as genome-wide significantly associated with AHI (P < 5.7 × 10-5), and European and Amerindian ancestries at 18q21 suggestively associated with both AHI and percentage time SaO2 < 90% (P < 10-3). Follow-up joint ancestry-SNP association analyses identified novel variants in ferrochelatase (FECH), significantly associated with AHI and percentage time SaO2 < 90% after adjusting for multiple tests (P < 8 × 10-6). These signals contributed to the admixture mapping associations and were replicated in independent cohorts. In this first admixture mapping study of OSA, novel associations with variants in the iron/heme metabolism pathway suggest a role for iron in influencing respiratory traits underlying OSA.

Relationship of genetic determinants of height with cardiometabolic and pulmonary traits in the Hispanic Community Health Study/Study of Latinos

Background

Associations of adult height with cardiometabolic and pulmonary traits have been studied in majority European ancestry populations using Mendelian randomization and polygenic risk score (PRS) analysis. The standard PRS approach entails creating a PRS for height using variants identified in prior genome-wide association studies (GWAS). It is unclear how well the standard PRS approach performs in non-European populations and whether height-trait associations observed in Europeans are also observed in other populations.

Methods

In the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), we used: (i) the standard approach to create a PRS for height (PRS1) and (ii) a novel approach to optimize the selection of variants from previously established height association loci to better explain height in HCHS/SOL (PRS2). We also estimated the extent to which PRS-trait associations were independent or mediated by the PRS effect on height.

Results

In 7539 women and 5245 men, PRS1 and PRS2 explained 9 and 29% of the variance in measured height, respectively. Both PRS1 and PRS2 were associated with forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/ FVC ratio, total cholesterol and 2-hour oral glucose-tolerance test insulin levels. Additionally, PRS2 was associated with estimated glomerular filtration rate and ankle brachial index. Both PRS1 and PRS2 had pleiotropic associations with FEV1/ FVC ratio in mediation analyses.

Conclusions

Associations of polygenic scores of height with measures of lung function and cholesterol were consistent with those observed in prior studies of majority European ancestry populations. Mediation analysis may augment standard PRS approaches to disentangle pleiotropic and mediated effects.

Sex Differences in the Association Between Smoking and Sleep-Disordered Breathing in the Hispanic Community Health Study/Study of Latinos

BACKGROUND

Results of previous studies examining associations between cigarette smoking and sleep-disordered breathing (SDB) are inconsistent. We therefore investigated this association in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

METHODS

A total of 13,863 US Hispanic/Latino subjects, 18 to 76 years old, provided smoking histories and underwent home SDB testing. Logistic regression analyses were conducted to assess the independent association of smoking and SDB with covariate adjustment. Sex- and age-stratified analyses were performed.

RESULTS

The weighted prevalence of moderate to severe SDB was 9.7% (95% CI, 9.0-10.5). No independent and statistically significant association was observed between ever smoking (defined as minimum lifetime cigarette use of 100) and moderate to severe SDB (defined as an apnea-hypopnea index ≥ 15 events per hour) (OR, 1.02; 95% CI, 0.85-1.22; P = .85). Sex and age were effect modifiers of the aforementioned association. Stratification according to age and sex revealed that younger (aged 35-54 years) female smokers had 83% higher odds of SDB compared with younger female never smokers (OR, 1.83; 95% CI, 1.19-2.81; P = .01). A significant dose-response relation was noted between smoking intensity and SDB in younger female smokers (P < .01). Lastly, use of ≥ 10 cigarettes per day was associated with a nearly threefold increase in SDB odds in younger female ever smokers. These associations were not observed in younger male subjects.

CONCLUSIONS

In the HCHS/SOL, no independent and statistically significant association was found between smoking and SDB. Sex and age stratification revealed a novel statistically significant association between smoking and SDB in younger (35-54 years old) female smokers. Our findings highlight the importance of investigating sex- and age-specific associations of SDB risk factors.

Associations of variants In the hexokinase 1 and interleukin 18 receptor regions with oxyhemoglobin saturation during sleep

Sleep disordered breathing (SDB)-related overnight hypoxemia is associated with cardiometabolic disease and other comorbidities. Understanding the genetic bases for variations in nocturnal hypoxemia may help understand mechanisms influencing oxygenation and SDB-related mortality. We conducted genome-wide association tests across 10 cohorts and 4 populations to identify genetic variants associated with three correlated measures of overnight oxyhemoglobin saturation: average and minimum oxyhemoglobin saturation during sleep and the percent of sleep with oxyhemoglobin saturation under 90%. The discovery sample consisted of 8,326 individuals. Variants with p < 1 × 10(-6) were analyzed in a replication group of 14,410 individuals. We identified 3 significantly associated regions, including 2 regions in multi-ethnic analyses (2q12, 10q22). SNPs in the 2q12 region associated with minimum SpO2 (rs78136548 p = 2.70 × 10(-10)). SNPs at 10q22 were associated with all three traits including average SpO2 (rs72805692 p = 4.58 × 10(-8)). SNPs in both regions were associated in over 20,000 individuals and are supported by prior associations or functional evidence. Four additional significant regions were detected in secondary sex-stratified and combined discovery and replication analyses, including a region overlapping Reelin, a known marker of respiratory complex neurons.These are the first genome-wide significant findings reported for oxyhemoglobin saturation during sleep, a phenotype of high clinical interest. Our replicated associations with HK1 and IL18R1 suggest that variants in inflammatory pathways, such as the biologically-plausible NLRP3 inflammasome, may contribute to nocturnal hypoxemia.

Sleep Timing, Stability, and BP in the Sueño Ancillary Study of the Hispanic Community Health Study/Study of Latinos

BACKGROUND

Timing and stability of the sleep-wake cycle are potential modifiable risk factors for cardiometabolic disease. The aim of this study was to evaluate the relationship between objective measures of sleep-wake timing and stability with cardiometabolic disease risk.

METHODS

In this multicenter, cross-sectional, population-based study, actigraphy data were obtained from the 2,156 adults, aged 18 to 64 years, recruited from the Sueño ancillary study of the Hispanic Community Health Study/Study of Latinos (2010-2013). These data were correlated with measures of cardiometabolic disease risk, including systolic and diastolic BPs, homeostatic assessment of insulin resistance, glycosylated hemoglobin, BMI, and hypertension and diabetes status.

RESULTS

Each 10% decrease in interdaily stability was associated with a 3.0% absolute increase in the prevalence of hypertension (95% CI, 0.6-5.3; P < .05), an increase in systolic BP by 0.78 mm Hg (95% CI, 0.12-1.45; P < .05) and an increase in diastolic BP by 0.80 mm Hg (95% CI, 0.28-1.32; P < .05). In addition, delaying the midpoint of sleep by 1 h was associated with an increase in systolic BP by 0.73 mm Hg (95% CI, 0.30-1.16; P < .01) and diastolic BP by 0.53 mm Hg (95% CI, 0.17-0.90; P < .01). These associations were not significant after adjusting for shift work status. No association was found between interdaily stability or sleep timing and diabetes, BMI, or insulin resistance.

CONCLUSIONS

These results suggest that beyond sleep duration, the timing and regularity of sleep-wake schedules are related to hypertension prevalence and BP.

An empirical model for magnetic field dependent resistivity and magnetoresistance in manganites: application on polycrystalline charge-ordered La0.4Gd0.1Ca0.5MnO3

In this paper, we have investigated the electrical and magnetic response of a La0.4Gd0.1Ca0.5MnO3 polycrystalline sample. This sample seems to exhibit fascinating phenomena like charge ordering, magnetic phase separation, training effects and kinetic arrest. It also shows colossal values of negative magnetoresistance (∼91.7% at 96 K under 1 T applied magnetic field), which raises the possibility of using this sample for technological applications. We have also proposed, in this work, a new empirical model to describe the evolution of resistivity and magnetoresistance as a function of magnetic field. This model was successfully tested on the La0.4Gd0.1Ca0.5MnO3 sample in spite of its complicated magnetic behavior, which suggests the use of this model for other magnetic samples in order to check its validity.

Multiethnic Meta-Analysis Identifies RAI1 as a Possible Obstructive Sleep Apnea-related Quantitative Trait Locus in Men

Obstructive sleep apnea (OSA) is a common heritable disorder displaying marked sexual dimorphism in disease prevalence and progression. Previous genetic association studies have identified a few genetic loci associated with OSA and related quantitative traits, but they have only focused on single ethnic groups, and a large proportion of the heritability remains unexplained. The apnea-hypopnea index (AHI) is a commonly used quantitative measure characterizing OSA severity. Because OSA differs by sex, and the pathophysiology of obstructive events differ in rapid eye movement (REM) and non-REM (NREM) sleep, we hypothesized that additional genetic association signals would be identified by analyzing the NREM/REM-specific AHI and by conducting sex-specific analyses in multiethnic samples. We performed genome-wide association tests for up to 19,733 participants of African, Asian, European, and Hispanic/Latino American ancestry in 7 studies. We identified rs12936587 on chromosome 17 as a possible quantitative trait locus for NREM AHI in men (N = 6,737; P = 1.7 × 10-8) but not in women (P = 0.77). The association with NREM AHI was replicated in a physiological research study (N = 67; P = 0.047). This locus overlapping the RAI1 gene and encompassing genes PEMT1, SREBF1, and RASD1 was previously reported to be associated with coronary artery disease, lipid metabolism, and implicated in Potocki-Lupski syndrome and Smith-Magenis syndrome, which are characterized by abnormal sleep phenotypes. We also identified gene-by-sex interactions in suggestive association regions, suggesting that genetic variants for AHI appear to vary by sex, consistent with the clinical observations of strong sexual dimorphism.

Current-voltage characteristics and electroresistance in LaMnO3-δ/La0.7Ca0.3MnO3/LaAlO3 thin film composites

In this communication, we report results of the electrical transport properties across the interface of composites consisting of n-type LaMnO_3-δ (LMO) and p-type La_0.7Ca_0.3MnO₃ (LCMO) manganites grown on LaAlO₃ (LAO) single crystalline substrates using low cost wet chemical solution deposition (CSD) and sophisticated, well-controlled dry chemical vapor deposition (CVD) chemical techniques. The XRD ϕ-scan studies reveal the single crystalline nature of both bilayered composites, with parallel epitaxial growth of LMO and LCMO layers onto the LAO substrate. The valence states of Mn ions in both layers of both composites were identified by performing X-ray photoelectron spectroscopy (XPS). The I-V characteristics of the LMO/LCMO interfaces show strong backward diode-like behavior at higher applied voltages well above the crossover voltage (V_NB). Below V_NB, the interfaces demonstrate normal diode-like characteristics throughout the studied temperature range. The electric field-induced modulation of the LMO/LCMO junction resistance of the interfaces has been observed. Electric field-dependent electroresistance (ER) modifications at different temperatures have also been studied. The electrical transport properties have been discussed in the context of various mechanisms, such as charge injection, tunneling, depletion region modification and thermal processes across the interface. The effects of structurally and chemically developed sharp interfaces between the LMO and LCMO layers on the transport properties of the presently studied bilayered thin film composites have been discussed on the basis of correlation between the physicochemical characterization and charge transport behavior. A comparison of different aspects of the transport properties has been presented in the context of the structural strain and crystallinity of the composites grown using both wet and dry chemical techniques.

Occlusion in the Flow of New Drugs for Cardiovascular Disease

There is a large misalignment between unmet need and both private and public investment activity in cardiovascular disease. In this paper, we quantify the magnitude of the gap, analyze a range of potential root causes in two main categories (issues of feasibility and valuation), and propose steps toward solutions to close the gap.

Correction: Charge transport mechanisms in sol-gel grown La0.7Pb0.3MnO3/LaAlO3 manganite films

Correction for 'Charge transport mechanisms in sol-gel grown La_0.7Pb_0.3MnO₃/LaAlO₃ manganite films' by Eesh Vaghela et al., Phys. Chem. Chem. Phys., 2017, DOI: 10.1039/c6cp07730g.

Charge transport mechanisms in sol-gel grown La0.7Pb0.3MnO3/LaAlO3 manganite films

In this communication, structural, microstructural, transport and magnetotransport properties are reported for La_0.7Pb_0.3MnO₃/LaAlO₃ (LPMO/LAO) manganite films having different thicknesses. All the films were irradiated with 200 MeV Ag⁺¹⁵ swift heavy ions (SHI). Films were grown using the sol-gel method by employing the acetate precursor route. Structural measurements were carried out using the X-ray diffraction (XRD) method at room temperature, while atomic force microscopy (AFM) was performed for the surface morphology. Temperature dependent resistivity under different applied magnetic fields for all the films shows metal to insulator transition at temperature T_P. In addition to the metal to insulator transition at T_P, the films also exhibit low temperature resistivity upturn behavior. Resistivity, T_P and upturn behavior are highly influenced by the film thickness, applied magnetic field and irradiation. To understand the nature of charge transport for the low temperature resistivity behavior and metallic and insulating (semiconducting) regions, various models and mechanisms have been verified and the most suitable mechanism has been found for each region in the resistivity curves. Magnetoresistance (MR) is affected by temperature, film thickness and irradiation. MR behavior has been understood in terms of combined and separate contributions from grains and grain boundaries in the films.

Neighborhood Factors as Predictors of Poor Sleep in the Sueño Ancillary Study of the Hispanic Community Health Study/Study of Latinos

Study Objectives

To evaluate whether an adverse neighborhood environment has higher prevalence of poor sleep in a US Hispanic/Latino population.

Methods

A cross-sectional analysis was performed in 2156 US Hispanic/Latino participants aged 18-64 years from the Sueño ancillary study of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Participants completed surveys of neighborhood environment including perceived safety, violence and noise, the Insomnia Severity Index (ISI), and 7 days of wrist actigraphy.

Results

In age and sex-adjusted analyses, short sleep, low sleep efficiency, and late sleep midpoint were all more prevalent among those living in an unsafe neighborhood. After adjustment for background, site, nativity, income, employment, depressive symptoms, and sleep apnea, the absolute risk of sleeping <6 hours was 7.7 (95% CI [0.9, 14.6]) percentage points greater in those living in an unsafe compared to a safe neighborhood. There were no differences in the prevalence of insomnia by level of safety or violence. Insomnia was more prevalent among those living in a noisy neighborhood. In adjusted analysis, the absolute risk of insomnia was 4.4 (95% CI [0.4, 8.4]) percentage points greater in those living in noisy compared to non-noisy neighborhoods.

Conclusion

Using validated measures of sleep duration and insomnia, we have demonstrated the existence of a higher prevalence of short sleep and insomnia by adverse neighborhood factors. An adverse neighborhood environment is an established risk factor for a variety of poor health outcomes. Our findings suggest negative effects on sleep may represent one pathway by which neighborhood environment influences health.

Genetic Associations with Obstructive Sleep Apnea Traits in Hispanic/Latino Americans

RATIONALE

Obstructive sleep apnea is a common disorder associated with increased risk for cardiovascular disease, diabetes, and premature mortality. Although there is strong clinical and epidemiologic evidence supporting the importance of genetic factors in influencing obstructive sleep apnea, its genetic basis is still largely unknown. Prior genetic studies focused on traits defined using the apnea-hypopnea index, which contains limited information on potentially important genetically determined physiologic factors, such as propensity for hypoxemia and respiratory arousability.

OBJECTIVES

To define novel obstructive sleep apnea genetic risk loci for obstructive sleep apnea, we conducted genome-wide association studies of quantitative traits in Hispanic/Latino Americans from three cohorts.

METHODS

Genome-wide data from as many as 12,558 participants in the Hispanic Community Health Study/Study of Latinos, Multi-Ethnic Study of Atherosclerosis, and Starr County Health Studies population-based cohorts were metaanalyzed for association with the apnea-hypopnea index, average oxygen saturation during sleep, and average respiratory event duration.

MEASUREMENTS AND MAIN RESULTS

Two novel loci were identified at genome-level significance (rs11691765, GPR83, P = 1.90 × 10-8 for the apnea-hypopnea index, and rs35424364; C6ORF183/CCDC162P, P = 4.88 × 10-8 for respiratory event duration) and seven additional loci were identified with suggestive significance (P < 5 × 10-7). Secondary sex-stratified analyses also identified one significant and several suggestive associations. Multiple loci overlapped genes with biologic plausibility.

CONCLUSIONS

These are the first genome-level significant findings reported for obstructive sleep apnea-related physiologic traits in any population. These findings identify novel associations in inflammatory, hypoxia signaling, and sleep pathways.

Transport properties and electroresistance of a manganite based heterostructure: role of the manganite-manganite interface

In this paper, we report the results of the investigations on the transport properties performed across the manganite-manganite interface in the LaMnO3-δ/La0.7Ca0.3MnO3/LaAlO3 (LMO/LCMO/LAO) heterostructure. The bilayered heterostructure was synthesized by a low cost and simple chemical solution deposition (CSD) method by employing the acetate precursor route. The same LMO/LCMO/LAO heterostructure was also grown using the dry metal oxide chemical vapor deposition (CVD) method and the results of transport characterization have been compared on the basis of wet and dry chemical methods used. XRD Φ-scan measurements were carried out to verify the structural quality and crystallographic orientations of LMO and LCMO manganite layers, for both wet and dry chemical method grown heterostructures. For wet and dry chemical methods, the temperature dependent resistance of the LMO/LCMO interface suggests the metallic nature. The asymmetric I-V curves collected at different temperatures show normal diode characteristics which get transformed to backward diode characteristics at high temperatures under high applied voltages at Vtr for both the methods. The values of Vtr are strongly dependent on the chemical method used. I-V data have been fitted using the Simmons model at different temperatures and discussed in terms of the spin-flip scattering mechanism for both wet and dry chemical method grown heterostructures. The electric field dependent electroresistance (ER) behavior of the presently studied LMO/LCMO manganite-manganite interface, grown using wet and dry chemical methods, has been understood on the basis of complex mechanisms including charge injection, formation of the depletion region, the tunneling effect, thermal processes and junction breakdown and their dependence on the applied electric field, field polarity and temperature studied.

Sleep Apnea Is Associated with Hearing Impairment: The Hispanic Community Health Study/Study of Latinos

STUDY OBJECTIVE

Sleep apnea (SA) may promote hearing impairment (HI) through ischemia and inflammation of the cochlea. Our objective was to assess an independent association between SA and HI in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) participants.

METHODS

We used data from the HCHS/SOL, a multicenter population-based study of self- identifying Hispanic/Latinos 18- to 74-y-old adults from four US urban communities. We performed home SA testing and in-clinic audiometry testing in all participants. SA was defined as an apnea-hypopnea index (AHI) ≥ 15 events/h. HI was defined as a mean hearing threshold > 25 dB hearing level in either ear at the frequencies: 3,000 to 8,000 Hz for high-frequency HI (HF-HI) and 500 to 2,000 Hz for low-frequency HI (LF-HI). Combined-frequency HI (CF-HI) was defined as both conditions present, and Any-HI was considered as HI in either low or high frequencies.

RESULTS

Of 13,967 participants, 9.9% had SA and 32.3% had Any-HI. Adjusted for risk factors for HI, those with SA had a 30% higher odds of Any-HI (95% confidence interval [CI] = 8% to 57%), 26% higher odds of HF-HI (CI = 3% to 55%), 127% higher odds of LF-HI (CI = 21% to 326%), and 29% higher odds of CF-HI (CI = 0% to 65%). A dose-response association was observed between AHI severity and Any-HI (versus no SA, OR for AHI ≥ 15 and < 30 = 1.22, CI = 0.96 to 1.54, and OR for AHI ≥ 30 = 1.46, CI = 1.11 to 1.91, p = 0.002).

CONCLUSION

SA is associated with HF-HI and LF-HI, independent of snoring and other confounders.

COMMENTARY

A commentary on this article appears in this issue on page 641.

Joint associations of insomnia and sleep duration with prevalent diabetes: The Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

BACKGROUND

Inadequate sleep quantity and quality are associated with a higher risk of type 2 diabetes. This relationship is not well-examined in U.S. Hispanics/Latinos, and prior analyses may be confounded by sleep apnea. This cross-sectional study examined joint associations of sleep duration and insomnia with diabetes among diverse U.S. Hispanic/Latinos.

METHODS

Baseline data on sleep quantity and quality were obtained from 15,227 participants (mean age 41; range 18-74 years) from the Hispanic Community Health Study/Study of Latinos. Complex survey multinomial logistic regression was used to examine associations between prevalent diabetes and six phenotypes defined by cross-classifying sleep duration (short ≤6 h, average >6-9 h, long >9 h) and insomnia, adjusting for sex, age, site and Hispanic/Latino background interaction, education, physical activity, diet quality, and sleep apnea.

RESULTS

In the weighted population, 14% had diabetes, 28% had insomnia, 9% were short sleepers, and 19% were long sleepers. Compared with those with average sleep and no insomnia, those with short sleep and insomnia were more likely to have diabetes (odds ratio [OR] 1.46; 95% confidence interval [CI] 1.02, 2.11). Average sleepers with insomnia (1.28; 95% CI 1.02, 1.61) and long sleepers without insomnia (1.33; 95% CI 1.07, 1.65) also had elevated odds of diabetes. Further adjustment for body mass index attenuated associations, except with long sleep without insomnia.

CONCLUSIONS

Both decreased quantity and quality of sleep are associated with diabetes in Hispanic/Latinos, with the greatest odds among those with short sleep duration and insomnia. The association is largely explained by obesity.

Comparison of Self-Reported Sleep Duration With Actigraphy: Results From the Hispanic Community Health Study/Study of Latinos Sueño Ancillary Study

Most studies of sleep and health outcomes rely on self-reported sleep duration, although correlation with objective measures is poor. In this study, we defined sociodemographic and sleep characteristics associated with misreporting and assessed whether accounting for these factors better explains variation in objective sleep duration among 2,086 participants in the Hispanic Community Health Study/Study of Latinos who completed more than 5 nights of wrist actigraphy and reported habitual bed/wake times from 2010 to 2013. Using linear regression, we examined self-report as a predictor of actigraphy-assessed sleep duration. Mean amount of time spent asleep was 7.85 (standard deviation, 1.12) hours by self-report and 6.74 (standard deviation, 1.02) hours by actigraphy; correlation between them was 0.43. For each additional hour of self-reported sleep, actigraphy time spent asleep increased by 20 minutes (95% confidence interval: 19, 22). Correlations between self-reported and actigraphy-assessed time spent asleep were lower with male sex, younger age, sleep efficiency <85%, and night-to-night variability in sleep duration ≥1.5 hours. Adding sociodemographic and sleep factors to self-reports increased the proportion of variance explained in actigraphy-assessed sleep slightly (18%-32%). In this large validation study including Hispanics/Latinos, we demonstrated a moderate correlation between self-reported and actigraphy-assessed time spent asleep. The performance of self-reports varied by demographic and sleep measures but not by Hispanic subgroup.

Improved Endurance and Resistive Switching Stability in Ceria Thin Films Due to Charge Transfer Ability of Al Dopant

An improvement in resistive switching (RS) characteristics of CeO2-based devices has been reported by charge transfer through Al metal as a dopant. Moreover, density functional theory (DFT) calculations have been performed to investigate the role of Al-layer sandwiched between CeO2 layers by the Vienna ab initio simulation package (VASP). Total density of states (TDOS) and partial electron density of states (PDOS) have been calculated and analyzed with respect to resistive switching. It is established that the oxygen vacancy based conductive filaments are formed and ruptured in the upper region of CeO2 layer, because of the fact that maximum transport of charge takes place in this region by Al and Ti (top electrode), while the lower region revealed less capability to generate conductive filaments because minimum charge transfer takes place in this region by Al and/or Pt (bottom electrode). The effect of Al and Al2O3 on both the electronic charge transfer from valence to conduction bands and the formation stability of oxygen vacancies in conductive filament have been discussed in detail. Experimental results demonstrated that the Ti/CeO2:Al/Pt sandwich structure exhibits significantly better switching characteristics including lower forming voltage, improved and stable SET/RESET voltages, enhanced endurance of more than 10(4) repetitive switching cycles and large memory window (ROFF/RON > 10(2)) as compared to undoped Ti/CeOx/Pt device. This improvement in memory switching behavior has been attributed to a significant decrease in the formation energy of oxygen vacancies and to the enhanced oxygen vacancies generation within the CeO2 layers owing to charge transferring and oxygen gettering ability of Al-dopant.

Gaze shifts and fixations dominate gaze behavior of walking cats

Vision is important for locomotion in complex environments. How it is used to guide stepping is not well understood. We used an eye search coil technique combined with an active marker-based head recording system to characterize the gaze patterns of cats walking over terrains of different complexity: (1) on a flat surface in the dark when no visual information was available, (2) on the flat surface in light when visual information was available but not required for successful walking, (3) along the highly structured but regular and familiar surface of a horizontal ladder, a task for which visual guidance of stepping was required, and (4) along a pathway cluttered with many small stones, an irregularly structured surface that was new each day. Three cats walked in a 2.5-m corridor, and 958 passages were analyzed. Gaze activity during the time when the gaze was directed at the walking surface was subdivided into four behaviors based on speed of gaze movement along the surface: gaze shift (fast movement), gaze fixation (no movement), constant gaze (movement at the body's speed), and slow gaze (the remainder). We found that gaze shifts and fixations dominated the cats' gaze behavior during all locomotor tasks, jointly occupying 62-84% of the time when the gaze was directed at the surface. As visual complexity of the surface and demand on visual guidance of stepping increased, cats spent more time looking at the surface, looked closer to them, and switched between gaze behaviors more often. During both visually guided locomotor tasks, gaze behaviors predominantly followed a repeated cycle of forward gaze shift followed by fixation. We call this behavior "gaze stepping". Each gaze shift took gaze to a site approximately 75-80cm in front of the cat, which the cat reached in 0.7-1.2s and 1.1-1.6 strides. Constant gaze occupied only 5-21% of the time cats spent looking at the walking surface.

Pulmonary hypertensive crisis following ethanol sclerotherapy for a complex vascular malformation

Anhydrous ethanol is a commonly used sclerotic agent for treating vascular malformations. We describe the case of a full-term 15-day-old female with a complex venolymphatic malformation involving the face and orbit. During treatment of the lesion with ethanol sclerotherapy, she suffered acute pulmonary hypertensive crisis. We discuss the pathophysiology of pulmonary hypertension related to ethanol sclerotherapy, and propose that hemolysis plays a significant role. Recommendations for evaluation, monitoring and management of this complication are also discussed.

Association between sleep and breast cancer incidence among postmenopausal women in the Women's Health Initiative

STUDY OBJECTIVES

To determine whether the duration of sleep, sleep quality, insomnia, or sleep disturbance was associated with incident breast cancer in the Women's Health Initiative (WHI).

DESIGN

Prospective cohort study.

SETTING

Women enrolled in one of the Clinical Trial (CT) arms or the Observational Study (OS) from the WHI conducted in the United States.

PARTICIPANTS

This study included 110,011 women age 50 to 79 years with no history of cancer.

MEASUREMENTS AND RESULTS

Typical sleep duration, sleep quality, and other self-reported sleep measures over the past 4 weeks were assessed during the screening visits for both the CT and OS participants. The presence of insomnia and level of sleep disturbance was calculated from an index of the WHI Insomnia Rating Scale. The outcome for this study was primary, invasive breast cancer. A total of 5,149 incident cases of breast cancer were identified in this study. No statistically significant associations were found between sleep duration, sleep quality, insomnia, or level of sleep disturbance with the risk of breast cancer after multivariable adjustment. A positive trend was observed for increasing sleeping duration with the risk of estrogen receptor positive breast cancer, but the association estimates for each sleep duration category were weak and nonsignificant.

CONCLUSIONS

This study does not provide strong support for an association between self-reported sleep duration, sleep quality, insomnia, or sleep disturbance with the risk of breast cancer.

Nano-engineering by implanting Al2O3 nano particle as sandwiched scattering centers in between the Lao.5Pr0.2Sr0.3MnO3 thin film layers

We report the use of non-magnetic Al2O3 nano particles deposited between two ferromagnetic La0.5Pr0.2Sr0.3MnO3 (LPSMO) manganite layers with an aim to improve the electronic and magnetotransport properties of the layered supper lattice grown on single crystal STO(100) substrate using Pulsed Laser Deposition (PLD) technique. We studied the electronic-transport and magnetotransport properties of this system wherein Al2O3 particles are expected to act as insulating scattering centers between two ferromagnetic LPSMO layers. The scattering due to additional scattering centers (insulating Al2O3 nano particles) could be controlled by application of external field, resulting in high magnetoresistance (MR) approximately 72% as compared to pristine LPSMO film (MR approximately 51%) at temperature close to their T(M) values. In addition, incorporation of nanostructured Al2O3 barrier between the two ferromagnetic LPSMO layers results in a 2-3 fold increase in the values of temperature coefficient of resistance (TCR) and the field coefficient of resistance (FCR) as compared to pristine LPSMO film, suggesting the use of such nanoengineered manganite layered structure for better device application.

The costoclavicular ligament revisited: a functional and anatomical study

INTRODUCTION

The sternoclavicular joint is of clinical importance. However, there is scant information in the literature regarding one ligament of this area, the costoclavicular ligament (CCL).

MATERIAL AND METHODS

In order to further elucidate this structure, 10 adult formalin-fixed cadavers (17 sides) underwent dissection of the CCL. Once the CCL was identified, measurements were made of its dimensions and observations made of its anatomy. Next, ranges of motion were performed of the upper extremity and the CCL observed for tension or laxity.

RESULTS

Of the 17 sternoclavicular regions examined 16 (94%) were found to possess a CCL. The average medial and lateral lengths, width and thickness were 1, 2, 1.2, 0.340 cm, respectively. The width of the CCL was statistically smaller in women that in men. The majority of ligaments were single structures traveling from the inferior surface of the medial clavicle just lateral and sometimes-fused (12.5%) to the lateral edge of the sternoclavicular joint. These fibers then terminated on the medial end of the first rib and first costal cartilage (75%) or exclusively onto the first costal cartilage (25%). Most ligaments were single and not composed of two parts. Arm abduction resulted in tautness of the ligament and increased as the degree of abduction increased. Internal rotation of the arm translated into medial shift of the clavicle, raising the clavicle away from the first rib creating tension on the CCL. Moderate degrees of external rotation were required before the CCL became taut and even began to pull the first rib laterally. Small amounts of protraction and retraction of the scapula both put the CCL under tension.

CONCLUSIONS

The CCL is a constant structure found just lateral to the sternoclavicular joint. This ligament was a single band in the majority of our specimens and limited most ranges of motion of the proximal upper limb thus stabilizing the sternoclavicular region.

Primary hepatic carcinoid tumor presenting as Cushing's syndrome

Hepatic carcinoid tumors are very uncommon; most are clinically non-functional and very few present with the symptoms of carcinoid syndrome. ACTH-producing carcinoid tumors most commonly originate in the lung or thymus and present insidiously with bronchospasm and/or chest mass. Occasionally, ectopic ACTH syndromes have been reported in association with pancreatic islet cell tumors, medullary thyroid cancer, pheochromocytoma, small-cell lung carcinoma, and rarely, ovarian and prostate tumors. We report here a patient with an ectopic ACTH-secreting primary hepatic carcinoid tumor who presented with cushingoid appearance, profound proximal muscle weakness, severe lower extremity edema, and markedly elevated urinary free cortisol. ACTH levels were in the low normal range. A solitary vascular hepatic lesion was found on magnetic resonance imaging, which was isodense with the surrounding liver on octreotide scan and photopenic on an 18-fluorodeoxyglucose (18FDG)-positron emission tomography (PET) scan. Following surgical resection of the hepatic tumor, histopathology confirmed an ACTH-secreting neuroendocrine tumor (NET), the patient had complete resolution of hypercortisolemic symptoms and remains in remission, now 4 yr after hepatic tumor resection. This case reports the first ACTH-secreting primary hepatic NET presenting as ectopic Cushing's syndrome. Interesting aspects of this case include the presence of a pituitary incidentaloma, the low normal ACTH, and photopenia on 18FDG-PET imaging.

Operative management of acetabular fractures. A review of 73 fractures

Between June 1994 and December 2000, 80 displaced acetabular fractures were treated by open reduction and internal fixation, where possible by a single surgical approach. We report our results in 72 patients (73 fractures) who completed a minimum follow-up of 2 years. The average age of patients was 39.5 years (range 15-76 years). Thirty-four fractures were classified as simple and the remaining 39 were complex fractures. Twenty-four patients were recorded to have posterior dislocation of the hip joint at the time of initial presentation and at surgery eight patients were noted to have varying degrees of damage to the head of the femur. The average time to surgery was 11.7 days (range 1-35 days); 80% of cases were operated within 2 weeks period. The average follow-up was 45.5 months (range 24-96 months). In 67 fractures (92%), only a single approach was used (Anterior Ilioinguinal 26 cases; Posterior Kocker-Lagenbach 41 cases). Five fractures needed an extensile triradiate approach and only one case required a combined anterior and posterior approach. Congruent reduction was achieved in 89% of cases. Main complications included deep infection in two patients (2.7%) and severe degenerative changes in three patients (4.2%). A total of four patients (5.5%) required a total hip replacement. There were no cases of deep vein thrombosis or pulmonary embolism. Heterotopic ossification grade III was seen in three (4.1%) cases and none were grade IV. At the latest follow-up the average Harris hip score was 85 (range 20-100). We conclude that in the majority of cases internal fixation is possible through a single approach provided patients are referred early to a specialist unit. This results in satisfactory outcome with reduced morbidity and complication rate.

Cellular automata and its advances to drug therapy for HIV infection

This paper gives an over view of the use of cellular automata (CA) model of drug therapy for HIV infection. Nonuniform CA is employed to simulate drug treatment of HIV infection, where each computational domain may contain different CA rules, in contrast to normal uniform CA models. Ordinary (or partial) differential equation models are insufficient to describe the two extreme time scales involved in HIV infection (days and decades), as well as the implicit spatial heterogeneity. Zorzenon and Coutinho [Phy Rev Lett, 16 (2001) 1] reported a cellular automata approach to simulate three-phase patterns of human immunodeficiency virus (HIV) infection consisting of primary response, clinical latency and onset of acquired immunodeficiency syndrome (AIDS). But here we present a related model, based on non-uniform CA to study the dynamics of drug therapy of HIV infection. The main aim in this model is to simulate the four phases (acute, chronic, drug treatment responds and onset of AIDS). The results shown here indicate that both simulations (with and without treatments) evolve to the relatively same steady state (characteristics of Wolfram's class II behavior). Different kinds of drug therapies can also be simulated in this model, which can be found useful for developing a proper drug therapy.

Identification of a mammalian long chain fatty acyl elongase regulated by sterol regulatory element-binding proteins

Fatty acids are synthesized de novo from acetyl-CoA and malonyl-CoA through a series of reactions mediated by acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS). In rodents, the principal fatty acid produced by FAS is palmitic acid (16:0). Sterol regulatory element-binding proteins (SREBPs) enhance the transcription of many genes responsible for fatty acid synthesis. In transgenic mice that overexpress SREBPs in liver, the rate of fatty acid synthesis is markedly increased, owing to the activation of these biosynthetic genes, which include ATP citrate lyase, ACC, FAS, and stearoyl-CoA desaturase. The fatty acids that accumulate in livers of SREBP transgenic mice are 18 carbons rather than 16 carbons in length, suggesting that the enzymes required for the elongation of palmitic to stearic acid may be induced. Here, we report the cDNA cloning of a murine long chain fatty acyl elongase (LCE) that was identified initially by oligonucleotide array analysis of mRNA from SREBP transgenic mouse livers. LCE mRNA is highly expressed in liver and adipose tissue. The cDNA encodes a protein of 267 amino acids that shares sequence identity with previously identified very long chain fatty acid elongases. Cells that overexpress LCE show enhanced addition of 2-carbon units to C12-C16 fatty acids. We provide evidence that LCE catalyzes the rate-limiting condensing step in this reaction. The current studies suggest that mouse LCE expression is increased by SREBPs and that the enzyme is a component of the elusive mammalian elongation system that converts palmitic to stearic acid.

High-throughput variation detection and genotyping using microarrays

The genetic dissection of complex traits may ultimately require a large number of SNPs to be genotyped in multiple individuals who exhibit phenotypic variation in a trait of interest. Microarray technology can enable rapid genotyping of variation specific to study samples. To facilitate their use, we have developed an automated statistical method (ABACUS) to analyze microarray hybridization data and applied this method to Affymetrix Variation Detection Arrays (VDAs). ABACUS provides a quality score to individual genotypes, allowing investigators to focus their attention on sites that give accurate information. We have applied ABACUS to an experiment encompassing 32 autosomal and eight X-linked genomic regions, each consisting of approximately 50 kb of unique sequence spanning a 100-kb region, in 40 humans. At sufficiently high-quality scores, we are able to read approximately 80% of all sites. To assess the accuracy of SNP detection, 108 of 108 SNPs have been experimentally confirmed; an additional 371 SNPs have been confirmed electronically. To access the accuracy of diploid genotypes at segregating autosomal sites, we confirmed 1515 of 1515 homozygous calls, and 420 of 423 (99.29%) heterozygotes. In replicate experiments, consisting of independent amplification of identical samples followed by hybridization to distinct microarrays of the same design, genotyping is highly repeatable. In an autosomal replicate experiment, 813,295 of 813,295 genotypes are called identically (including 351 heterozygotes); at an X-linked locus in males (haploid), 841,236 of 841,236 sites are called identically.

The Lubinus patellofemoral arthroplasty. A five- to ten-year prospective study

We present a prospective review of the outcome of 76 Lubinus patellofemoral arthroplasties carried out in 59 patients between 1989 and 1995. At a mean follow-up of 7.5 years, 62 knees in the 48 patients were reviewed; 11 patients (14 knees) had died. None was lost to follow-up. The clinical outcome using the Bristol Knee Scoring system was satisfactory in 45% of the cases. Maltracking of the patella, resulting in lateral tilt, subluxation and polyethylene wear, was the most common complication (32%). Revision surgery was carried out in 21 knees (28%) giving a cumulative survival rate of 65% (confidence interval (CI) 49 to 77) at eight years. The survival rate for revision and moderate pain was 48% (CI 36 to 59) at six years. Progression of arthritis was seen in seven cases (9%). In five of these (6.5%), the symptoms were severe enough to need revision surgery. Due to the high proportion of unsatisfactory results, we have discontinued the use of this prosthesis.

Copper, zinc, and magnesium levels in non-insulin dependent diabetes mellitus

A relationship has been reported between trace elements and diabetes mellitus. This study evaluated the role of such a relationship in 83 patients with non-insulin dependent diabetes mellitus (40 men and 43 women), with a mean duration of diabetes of 3.9 +/- 3.6 years. Patients with nephropathy were excluded. Thirty healthy non-diabetic subjects were studied for comparative analysis. Subjects were subdivided into obese and non-obese. Diabetic subjects were also subdivided into controlled and uncontrolled groups; control was based on fasting blood glucose and serum fructosamine levels. Plasma copper, zinc and magnesium levels were analysed using a GBC 902 double beam atomic absorption spectrophotometer. Plasma zinc and magnesium levels were comparable between diabetic and non-diabetic subjects, while copper levels were significantly elevated (p < 0.01) in diabetic patients. Age, sex, duration and control of diabetes did not influence copper, zinc, or magnesium concentrations. We conclude that zinc and magnesium levels are not altered in diabetes mellitus, but the increased copper levels found in diabetics in our study may merit further investigation of the relationship between copper and non-insulin dependent diabetes mellitus.

Unicompartmental or total knee replacement? Five-year results of a prospective, randomised trial of 102 osteoarthritic knees with unicompartmental arthritis

We randomised 102 knees suitable for a unicompartmental replacement to receive either a unicompartmental (UKR) or total knee replacement (TKR) after arthrotomy. Both groups were well matched with a predominance of females and a mean age of 69 years. Patients in the UKR group showed less perioperative morbidity, but regained knee movement more rapidly and were discharged from hospital sooner. At five years, two UKRs and one TKR had been revised; another TKR was radiologically loose. All other knees appeared to be clinically and radiologically sound. Pain relief was good in both groups but the number of knees able to flex > or =120 degrees was significantly higher in the UKR group (p < 0.001) and there were more excellent results in this group. Our findings have shown that UKR gives better results than TKR and that this superiority is maintained for at least five years.

Diet and lifestyle guidelines and desirable levels of risk factors for the prevention of diabetes and its vascular complications in Indians: a scientific statement of The International College of Nutrition. Indian Consensus Group for the Prevention of Diabetes

BACKGROUND

There has been a rapid increase in the prevalence of diabetes and cardiovascular disease in India, in association with rapid changes in diet and lifestyle. In adults, the prevalence of diabetes, hypertension and coronary artery disease is two- to threefold greater in the urban population than in rural populations; it is associated with modest insulin resistance in urban groups.

METHODS

In response to a proposal by the International College of Nutrition that specialist experts should develop consensus recommendations for the prevention of chronic diseases, Indian specialists in diabetes and vascular disease have collaborated to produce guidelines relevant to the population of India.

RECOMMENDATIONS

Because Indian urban populations have a modest increase in overweight and low rates of obesity in association with the rapid emergence of diabetes and cardiovascular risk, a body mass index of 21 kg/m2 should be considered safe, with a range of 19-23 kg/m2 acceptable; > 23 kg/m2 should be considered overweight, and > 25 kg/m2 should be taken to indicate obesity. A waist:hip ratio > 0.88 in males and > 0.85 in females should be considered to indicate central obesity, because the prevalence of coronary disease, hypertension and associated disturbances of insulin resistance are more common above these limits. For the prevention of vascular disease, there is general international consensus that the desirable serum concentration of cholesterol should be < 170 mg/dl (> 4.42 mmol/l), which may also be optimal for Indians; values between 170 and 200 mg/dl (4.42-5.2 mmol/l) should be considered borderline. The critical values for low density lipoprotein cholesterol may be < 90 mg/dl (ideal), 90-110 mg/dl (borderline high) and > 110 mg/dl (high) (< 2.32, 2.32-2.84 and > 2.84 mmol/l, respectively). Fasting triglycerides should be < 150 mg/dl (< 1.69 mmol/l) and high-density lipoprotein cholesterol > 35 mg/dl (> 0.9 mmol/l). The limit for the total energy derived from fat intake should be < 21%/day (7% each for saturated, polyunsaturated and mono-unsaturated fatty acids). The carbohydrate intake should provide more than 65% of daily energy, mainly from complex carbohydrates. A daily dietary intake of 400 g fruits, vegetables and legumes, 400 g cereals, in conjunction with 25 g soya bean or mustard or canola oils (rich in n-3 fatty acids) in place of fats rich in saturated fat, may be protective against diabetes and vascular disease. Moderate physical activity with the aim of burning 300 Kcal/day (> 1255 KJ/day), and cessation of tobacco and alcohol consumption, may provide an effective programme for prevention of diabetes and its vascular complications in Indians.

Prevalence of goitre in school children in Baramulla (Kashmir valley)

1,876 school children were surveyed in Baramulla district of Kashmir for the presence of goitre. There were 964 boys and 912 girls in the age group of 5-15 years. An overall goitre prevalence of 52.08 per cent was found (54.77% in boys and 49.23% in girls). Iodine content was assayed in urine samples of 44 randomly selected subjects. The mean +/- SEM urinary iodine was 41.85 +/- 2.52 micrograms/g of creatinine (Range 6.25-69.41).