Associations of Lower Extremity Muscle Strength, Area, and Specific Force With Lower Urinary Tract Symptoms in Older Men: The Baltimore Longitudinal Study of Aging

BACKGROUND

Lower urinary tract symptoms (LUTS) in older men are associated with an increased risk of mobility limitations. Lower extremity muscle quality may represent a novel shared mechanism of both LUTS and mobility limitations.

METHODS

We evaluated associations of thigh skeletal muscle measures (strength, area, and specific force) with total LUTS severity (American Urologic Association Symptom Index; AUASI) and voiding and storage subscores among 352 men aged ≥60 years enrolled in the Baltimore Longitudinal Study of Aging. Thigh muscle strength (Nm) was defined as maximum concentric 30°/s knee extensor torque, area (cm2), and specific force (Nm/cm2) defined as strength/area. Associations with AUASI score were estimated using multivariable linear regression and linear mixed models.

RESULTS

Mean thigh muscle strength at baseline was 139.7Nm. In cross-sectional multivariable models, each 39Nm increment in thigh muscle strength and 0.28Nm/cm2 increment in specific force was associated with -1.17 point (95% CI: -1.93 to -.41) and -0.95 point (95% CI: -1.63 to -0.27) lower AUASI score, respectively. Similar associations were observed for voiding and storage subscores, although somewhat attenuated. In longitudinal analyses, baseline muscle measures were not associated with annual change in AUASI, and current changes in muscle measures and AUASI were unrelated.

CONCLUSIONS

Cross-sectionally, higher thigh muscle strength and specific force were associated with decreased LUTS severity in older men. However, we did not observe concurrent worsening LUTS severity with declining thigh muscle strength, area, or specific force in longitudinal analyses.

Skeletal Muscle Health, Physical Performance, and Lower Urinary Tract Symptoms in Older Adults: The Study of Muscle, Mobility, and Aging

BACKGROUND

Lower urinary tract symptoms (LUTS) and mobility limitations are bidirectionally associated among older adults, but the role of skeletal muscle remains unknown. We evaluated cross-sectional associations of muscle health and physical performance with LUTS.

METHODS

We used data from 377 women and 264 men aged >70 years in the Study of Muscle, Mobility and Aging (SOMMA). LUTS and urinary bother were assessed using the LURN Symptom Index-10 (SI-10; higher = worse symptoms). Muscle mass and volume were assessed using D3-creatine dilution (D3Cr) and magnetic resonance imaging. Grip strength and peak leg power assessed upper/lower extremity physical performance. 400-m walk, Short Physical Performance Battery (SPPB), and Four Square Step Test (FSST) assessed global physical performance. Mobility Assessment Tool-short form (MAT-sf) assessed self-reported mobility. We calculated Spearman correlation coefficients adjusted for age, body mass index, multimorbidity, and polypharmacy, chi-square tests, and Fisher's Z-test to compare correlations.

RESULTS

Among women, LURN SI-10 total scores were inversely correlated with FSST (rs = 0.11, p = .045), grip strength (rs = -0.15, p = .006), and MAT-sf (rs = -0.18, p = .001), but not other muscle and physical performance measures in multivariable models. LURN SI-10 was not associated with any of these measures among men. Forty-four percent of women in the lowest tertile of 400-m walk speed versus 24% in the highest tertile reported they were at least "somewhat bothered" by urinary symptoms (p < .001), whereas differences among men were not significant.

CONCLUSIONS

Balance and grip strength were associated with LUTS severity in older women but not men. Associations with other muscle and physical performance measures varied by LUTS subtype but remained strongest among women.

Aging-Related Mitochondrial Dysfunction Is Associated With Fibrosis in Benign Prostatic Hyperplasia

BACKGROUND

Age is the greatest risk factor for lower urinary tract symptoms attributed to benign prostatic hyperplasia (LUTS/BPH). Although LUTS/BPH can be managed with pharmacotherapy, treatment failure has been putatively attributed to numerous pathological features of BPH (eg, prostatic fibrosis, inflammation). Mitochondrial dysfunction is a hallmark of aging; however, its impact on the pathological features of BPH remains unknown.

METHODS

Publicly available gene array data were analyzed. Immunohistochemistry examined mitochondrial proteins in the human prostate. The effect of complex I inhibition (rotenone) on a prostatic cell line was examined using quantitative polymerase chain reaction, immunocytochemistry, and Seahorse assays. Oleic acid (OA) was tested as a bypass of complex I inhibition. Aged mice were treated with OA to examine its effects on urinary dysfunction. Voiding was assessed longitudinally, and a critical complex I protein measured.

RESULTS

Mitochondrial function and fibrosis genes were altered in BPH. Essential mitochondrial proteins (ie, voltage-dependent anion channels 1 and 2, PTEN-induced kinase 1, and NADH dehydrogenase [ubiquinone] iron-sulfur protein 3, mitochondrial [NDUFS3]) were significantly (p < .05) decreased in BPH. Complex I inhibition in cultured cells resulted in decreased respiration, altered NDUFS3 expression, increased collagen deposition, and gene expression. OA ameliorated these effects. OA-treated aged mice had significantly (p < .05) improved voiding function and higher prostatic NDUFS3 expression.

CONCLUSIONS

Complex I dysfunction is a potential contributor to fibrosis and lower urinary tract dysfunction in aged mice. OA partially bypasses complex I inhibition and therefore should be further investigated as a mitochondrial modulator for treatment of LUTS/BPH. Hypotheses generated in this investigation offer a heretofore unexplored cellular target of interest for the management of LUTS/BPH.

Age-Dependent Effects of Voluntary Wheel Running Exercise on Voiding Behavior and Potential Age-Related Molecular Mechanisms in Mice

BACKGROUND

Older men frequently develop lower urinary tract symptoms attributed to benign prostatic hyperplasia (LUTS/BPH). Risk factors for LUTS/BPH include sedentary lifestyle, anxiety/depression, obesity, and frailty, which all increase with age. Although physical exercise may reduce the progression and/or severity of LUTS/BPH, the age-related mechanisms responsible remain unknown.

METHODS

Voiding symptoms, body mass, and frailty were assessed after 4-weeks of voluntary wheel running in 2-month (n = 10) and 24-month (n = 8) old C57Bl/6J male mice. In addition, various social and individual behaviors were examined in these cohorts. Finally, cellular and molecular markers of inflammation and mitochondrial protein expression were assessed in prostate tissue and systemically.

RESULTS

Despite running less (aged vs young X¯ = 12.3 vs 30.6 km/week; p = .04), aged mice had reduced voiding symptoms (X¯ = 67.3 vs 23.7; p < .0001) after 1 week of exercise, which was sustained through week 4 (X¯ = 67.3 vs 21.5; p < .0001). Exercise did not affect voiding symptoms in young mice. Exercise also increased mobility and decreased anxiety in both young and aged mice (p < .05). Exercise decreased expression of a key mitochondrial protein (PINK1; p < .05) and inflammation within the prostate (CD68; p < .05 and plasminogen activator inhibitor-1; p < .05) and in the serum (p < .05). However, a frailty index (X¯ = 0.17 vs 0.15; p = .46) and grip strength (X¯ = 1.10 vs 1.19; p = .24) were unchanged after 4 weeks of exercise in aged mice.

CONCLUSIONS

Voluntary aerobic exercise improves voiding behavior and mobility, and decreases prostatic mitochondrial protein expression and inflammation in aged mice. This promising model could be used to evaluate molecular mechanisms of aerobic exercise as a novel lifestyle intervention for older men with LUTS/BPH.

Plant-based diet associated with better quality of life in prostate cancer survivors

BACKGROUND

Plant-based diets have many health benefits, including a lower risk of fatal prostate cancer, and greater environmental sustainability. However, less is known regarding the impact of plant-based diets on quality of life among individuals diagnosed with prostate cancer. The authors' objective was to examine the relationship between plant-based diet indices postdiagnosis with quality of life.

METHODS

This prospective cohort study included 3505 participants in the Health Professionals Follow-Up Study (1986-2016) with nonmetastatic prostate cancer. Food-frequency questionnaires were used to calculate overall and healthful plant-based diet indices. Quality-of-life scores were calculated using the Expanded Prostate Cancer Index Composite. Generalized estimating equations were used to examine associations over time between plant-based diet indices and quality-of-life domains (sexual functioning, urinary irritation/obstruction, urinary incontinence, bowel functioning, hormonal/vitality), adjusted for demographics, oncologic history, body mass index, caloric intake, health-related behaviors, and comorbidities.

RESULTS

The median age at prostate cancer diagnosis was 68 years; 48% of patients underwent radical prostatectomy, and 35% received radiation as primary therapy. The median time from diagnosis/treatment to first the quality-of-life questionnaire was 7.0 years. A higher plant-based diet index was associated with better scores for sexual function, urinary irritation/obstruction, urinary incontinence, and hormonal/vitality. Consuming more healthful plant-based foods was also associated with better sexual and bowel function, as well as urinary incontinence and hormonal/vitality scores in the age-adjusted analysis, but not in the multivariable analysis.

CONCLUSIONS

This prospective study provides supportive evidence that greater consumption of healthful plant-based foods is associated with modestly higher scores in quality-of-life domains among patients with prostate cancer.

Lower muscle mitochondrial energetics is associated with greater phenotypic frailty in older women and men: the Study of Muscle, Mobility and Aging

BACKGROUND

Phenotypic frailty syndrome identifies older adults at greater risk for adverse health outcomes. Despite the critical role of mitochondria in maintaining cellular function, including energy production, the associations between muscle mitochondrial energetics and frailty have not been widely explored in a large, well-phenotyped, older population.

METHODS

The Study of Muscle, Mobility and Aging (SOMMA) assessed muscle energetics in older adults (N = 879, mean age = 76.3 years, 59.2% women). 31Phosporous magnetic resonance spectroscopy measured maximal production of adenosine triphosphate (ATPmax) in vivo, while ex vivo high-resolution respirometry of permeabilized muscle fibers from the vastus lateralis measured maximal oxygen consumption supported by fatty acids and complex I- and II-linked carbohydrates (e.g., Max OXPHOSCI+CII). Five frailty criteria, shrinking, weakness, exhaustion, slowness, and low activity, were used to classify participants as robust (0, N = 397), intermediate (1-2, N = 410), or frail (≥ 3, N = 66). We estimated the proportional odds ratio (POR) for greater frailty, adjusted for multiple potential confounders.

RESULTS

One-SD decrements of most respirometry measures (e.g., Max OXPHOSCI+CII, adjusted POR = 1.5, 95%CI [1.2,1.8], p = 0.0001) were significantly associated with greater frailty classification. The associations of ATPmax with frailty were weaker than those between Max OXPHOSCI+CII and frailty. Muscle energetics was most strongly associated with slowness and low physical activity components.

CONCLUSIONS

Our data suggest that deficits in muscle mitochondrial energetics may be a biological driver of frailty in older adults. On the other hand, we did observe differential relationships between measures of muscle mitochondrial energetics and the individual components of frailty.

Structured Moderate Exercise and Biomarkers of Kidney Health in Sedentary Older Adults: The Lifestyle Interventions and Independence for Elders Randomized Clinical Trial

Rationale & Objective

In the Lifestyle Interventions and Independence for Elders (LIFE) trial, a structured exercise intervention slowed kidney function decline in sedentary older adults. Biomarkers of kidney health could distinguish potential mechanisms for this beneficial effect.

Study Design

Randomized controlled trial.

Setting & Population

A total of 1,381 sedentary adults aged 70-89 years enrolled in the LIFE trial.

Intervention

Structured, 2-year, moderate-intensity exercise intervention versus health education.

Outcomes

Physical activity was measured by step count. Primary outcomes were changes in 14 serum and urine biomarkers of kidney health collected at baseline, year 1, and year 2. We determined the effect of randomization on changes in kidney measures and then evaluated observational associations of achieved activity on each measure.

Results

Participants assigned to exercise walked on average 291 more steps per day than participants assigned to health education. The intervention was not significantly associated with changes in biomarkers of kidney health. In observational analyses, persons in the highest versus lowest quartile of activity (≥3,470 vs <1,568 steps/day) had significant improvement in urine albumin (mean, -0.22 mg albumin/g urine creatinine [interquartile range (IQR), -0.37 to -0.06]), alpha-1-microglobulin (-0.18 mg/L [-0.28 to -0.08]), trefoil factor-3 (-0.24 pg/mL [-0.35 to -0.13]), epidermal growth factor (0.19 pg/mL [0.06-0.32]), uromodulin (0.06 pg/mL [0.00-0.12]), interleukin 18 (-0.09 pg/mL [-0.15 to -0.03]), neutrophil gelatinase-associated lipocalin (-0.16 pg/mL [-0.24 to -0.07]), monocyte chemoattractant protein-1 (-0.25 pg/mL [-0.36 to -0.14]), clusterin (-0.16 pg/mL [-0.30 to -0.02]), serum tumor necrosis factor receptor-1 (-0.25 mg/dL [-0.39 to -0.11]) and tumor necrosis factor receptor-2 (-0.30 mg/dL [-0.44 to -0.16]). In sensitivity analyses, incremental changes in activity were most impactful on urine interleukin 18 and serum tumor necrosis factor-1.

Limitations

The original study was not designed to assess the impact on kidney health. Non-white individuals and patients with advanced chronic kidney disease are underrepresented.

Conclusions

Randomization to structured exercise did not improve kidney health at a group level. However, higher exercise was associated with concurrent improvements in biomarkers of glomerular injury, tubular function/repair, tubular injury, generalized inflammation, and tubulointerstitial repair/fibrosis.

Plain-Language Summary

In the Lifestyle Interventions For Elders (LIFE) study, randomization to an exercise and physical activity intervention improved the slope of estimated glomerular filtration rate over 2 years compared with health education among older adults. In this study, we sought to determine whether there were specific biomarkers of kidney health that were affected by the exercise and physical activity intervention to investigate potential mechanisms for this positive impact on kidney decline. We found that randomization to the intervention did not improve any of the 14 measures of kidney tubule health. However, in observational analyses, higher activity was independently associated with improvements in several domains, especially tubular injury and generalized inflammation. These results help to clarify the impact of physical activity on kidney health.

Lower urinary tract symptom severity, urinary bother, and incident life-space mobility restriction among older men

BACKGROUND

Life-space mobility represents the distance, frequency, and independence of mobility, ranging from one's bedroom to beyond their town. Older men with lower urinary tract symptoms (LUTS) may limit their life-space to stay close to a bathroom. However, it's unknown whether LUTS severity or urinary bother are associated with risk of life-space mobility restriction.

METHODS

We analyzed data from 3025 community-dwelling men age ≥71 years without life-space mobility restriction at analytic baseline (Year 7) of the Osteoporotic Fractures in Men (MrOS) study. The American Urologic Association Symptom Index (AUASI) was assessed at baseline and includes one question assessing urinary bother ("If you were to spend the rest of your life with your urinary condition just the way it is now, how would you feel about that?"; score 0-1,2,3,4-6) and seven items to classify LUTS severity as none/mild (score 0-7), moderate (8-19), or severe (20-35). The University of Alabama Life-space Assessment was used to define life-space mobility restriction (≤60) at baseline and follow-up (Year 9). We used log-binomial regression with robust variance estimators to model adjusted risk ratios (ARR) for LUTS severity and urinary bother with incident life-space mobility restriction, controlling for age, site, health-related factors, and comorbidities. We then mutually adjusted for urinary bother and LUTS severity.

RESULTS

Overall, the 2-year risk of life-space mobility restrictions was 9.9%. Compared to men without urinary bother (scores 0-1), the risk of life-space mobility restriction was significantly higher among men with bother scores of 4-6 (ARR = 2.20, 95% CI: 1.52, 3.19), independent of LUTS severity and confounders. Conversely, LUTS severity was not independently associated with the risk of life-space mobility restriction.

CONCLUSIONS

Urinary bother, but not LUTS severity, is independently associated with incident life-space mobility restriction among older men. To maintain life-space mobility in older men with LUTS, future studies should identify shared mechanisms and interventions that minimize urinary bother.

Longitudinal Associations between Concurrent Changes in Phenotypic Frailty and Lower Urinary Tract Symptoms among Older Men

BACKGROUND

Lower urinary tract symptoms (LUTS) are associated with prevalent frailty and functional impairment, but longitudinal associations remain unexplored.

OBJECTIVES

To assess the association of change in phenotypic frailty with concurrent worsening LUTS severity among older men without clinically significant LUTS at baseline.

DESIGN

Multicenter, prospective cohort study.

SETTING

Population-based.

PARTICIPANTS

Participants included community-dwelling men age ≥65 years at enrollment in the Osteoporotic Fractures in Men study.

MEASUREMENTS

Data were collected at 4 visits over 7 years. Phenotypic frailty score (range: 0-5) was defined at each visit using adapted Fried criterion and men were categorized at baseline as robust (0), pre-frail (1-2), or frail (3-5). Within-person change in frailty was calculated at each visit as the absolute difference in number of criteria met compared to baseline. LUTS severity was defined using the American Urologic Association Symptom Index (AUASI; range: 0-35) and men with AUASI ≥8 at baseline were excluded. Linear mixed effects models were adjusted for demographics, health-behaviors, and comorbidities to quantify the association between within-person change in frailty and AUASI.

RESULTS

Among 3235 men included in analysis, 48% were robust, 45% were pre-frail, and 7% were frail. Whereas baseline frailty status was not associated with change in LUTS severity, within-person increases in frailty were associated with greater LUTS severity (quadratic P<0.001). Among robust men at baseline, mean predicted AUASI during follow-up was 4.2 (95% CI 3.9, 4.5) among those meeting 0 frailty criteria, 4.6 (95% CI 4.3, 4.9) among those meeting 1 criterion increasing non-linearly to 11.2 (95% CI 9.8, 12.6) among those meeting 5 criteria.

CONCLUSIONS

Greater phenotypic frailty was associated with non-linear increases in LUTS severity in older men over time, independent of age and comorbidities. Results suggest LUTS and frailty share an underlying mechanism that is not targeted by existing LUTS interventions.

Research priorities for measuring biologic age: summary and future directions from the Research Centers Collaborative Network Workshop

Biologic aging reflects the genetic, molecular, and cellular changes underlying the development of morbidity and mortality with advancing chronological age. As several potential mechanisms have been identified, there is a growing interest in developing robust measures of biologic age that can better reflect the underlying biology of aging and predict age-related outcomes. To support this endeavor, the Research Centers Collaborative Network (RCCN) conducted a workshop in January 2022 to discuss emerging concepts in the field and identify opportunities to move the science forward. This paper presents workshop proceedings and summarizes the identified research needs, priorities, and recommendations for measuring biologic age. The highest priorities identified were the need for more robust measures, longitudinal studies, multidisciplinary collaborations, and translational approaches.

Plant-based diet index and erectile dysfunction in the Health Professionals Follow-Up Study

OBJECTIVE

To evaluate the longitudinal association between plant-based diet index (PDI) score and incident erectile dysfunction (ED).

MATERIALS AND METHODS

We conducted a prospective analysis of 21 942 men aged 40 to 75 years who were enrolled in the Health Professionals Follow-Up Study. ED was assessed with questionnaires every 4 years starting in 2000. Dietary data were collected via validated food frequency questionnaires completed every 4 years and were used to calculate total PDI scores, as well as healthy (hPDI) and unhealthy (uPDI) subscores. Multivariable Cox proportional hazards models were used to compute hazard ratios (HRs) for incident ED. All models were stratified by age (<60, 60 to <70, ≥70 years).

RESULTS

Among men aged 60 to <70 years, hPDI was inversely associated with incident ED. Those in the highest quintile of hPDI in that age group had an 18% lower risk of ED (HR 0.82, 95% confidence interval (CI) 0.73-0.91; P-trend <0.001) compared to those in the lowest quintile. Conversely, uPDI was positively associated with ED in men aged <60 years (HR 1.27, 95% CI 1.01-1.60; P-trend = 0.02).

CONCLUSIONS

Encouraging a healthy plant-based diet may be an environmentally sustainable intervention for men interested in maintaining erectile function.

Lower urinary tract symptoms and incident functional limitations among older community-dwelling men

BACKGROUND

Lower urinary tract symptoms (LUTS) are associated with frailty phenotype, a risk factor for functional decline. Our objective was to determine the association between baseline LUTS and 2-year risk of new functional limitation among older men.

METHODS

We analyzed data from the Osteoporotic Fractures in Men (MrOS) study with baseline at Year 7 and follow-up through Year 9. Participants included 2716 community-dwelling men age ≥ 71 years without any baseline self-reported functional limitation. LUTS severity (American Urologic Association Symptom Index) was classified as none/mild (score 0-7), moderate (8-19), and severe (20-35). At baseline and follow-up, men reported their ability to complete several mobility, activities of daily living (ADLs), and cognition-dependent tasks. Risk was estimated for 3 incident functional limitation outcomes: (1) mobility (any difficulty walking 2-3 blocks or climbing 10 steps), (2) ADL (any difficulty bathing, showering, or transferring), and (3) cognition-dependent (any difficulty managing money or medications). We used Poisson regression with a robust variance estimator to model adjusted risk ratios (ARR) and 95% CIs controlling for age, site, and comorbidities; other demographic/lifestyle factors did not meet criteria for inclusion.

RESULTS

Overall, the 2-year risk was 15% for mobility, 10% for ADLs, and 4% for cognition-dependent task limitations. Compared to none/mild LUTS, risk of incident mobility limitations was increased for moderate (ARR = 1.35, 95% CI: 1.12, 1.63) and severe LUTS (ARR = 1.98, 95% CI: 1.48, 2.64). Men were also at higher risk for incident ADL limitations if they reported moderate (ARR = 1.32, 95% CI: 1.05, 1.67) and severe LUTS (ARR = 1.62, 95% CI: 1.07,2.43). Results were somewhat attenuated after adjusting for the frailty phenotype but remained statistically significant. LUTS were not associated with incident cognition-dependent task limitations.

CONCLUSIONS

LUTS severity is associated with incident mobility and ADL limitations among older men. Increased clinical attention to risk of functional limitations among older men with LUTS is likely warranted.

Association of Intraindividual Difference in Estimated Glomerular Filtration Rate by Creatinine vs Cystatin C and End-stage Kidney Disease and Mortality

Importance

As cystatin C is increasingly adopted to estimate glomerular filtration rate (eGFR), clinicians will encounter patients in whom cystatin C-based eGFR (eGFRcys) and creatinine-based eGFR (eGFRcr) differ widely. The clinical implications of these differences, eGFRdiffcys-cr, are unknown.

Objective

To evaluate the associations of eGFRdiffcys-cr with end-stage kidney disease (ESKD) and mortality among individuals with chronic kidney disease (CKD).

Design, Setting, and Participants

This is a prospective cohort study of 4956 individuals with mild to moderate CKD from 7 clinical centers in the United States who enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study between 2003 to 2018. Statistical analyses were completed in December 2021.

Exposures

eGFRdiffcys-cr (eGFRcys - eGFRcr) was calculated at baseline and annually thereafter for 3 years. Because 15 mL/min/1.73 m2 represents a clinically meaningful difference in eGFR that also distinguishes CKD stages, eGFRdiffcys-cr was categorized as: less than -15 mL/min/1.73 m2, -15 to 15 mL/min/1.73 m2, and 15 mL/min/1.73 m2 or greater.

Main Outcomes and Measures

The outcomes of ESKD, defined as initiation of maintenance dialysis or receipt of a kidney transplant, and all-cause mortality were adjudicated from study entry until administrative censoring in 2018.

Results

Among 4956 participants with mean (SD) age of 59.5 (10.5) years, 2152 (43.4%) were Black, 515 (10.4%) were Hispanic, and 2113 (42.6%) were White. There were 2156 (43.5%) women and 2800 (56.5%) men. At baseline, eGFRcys and eGFRcr values differed by more than 15 mL/min/1.73 m2 in one-third of participants (1638 participants [33.1%]). Compared with participants with similar baseline eGFRcys and eGFRcr (eGFRdiffcys-cr -15 to 15 mL/min/1.73 m2), those in whom eGFRcys was substantially lower than eGFRcr (eGFRdiffcys-cr < -15 mL/min/1.73 m2) had a higher risk of mortality (hazard ratio [HR], 1.86; 95% CI, 1.40-2.48) while those with eGFRdiffcys-cr of 15 mL/min/1.73 m2 or greater had lower risks of ESKD (subHR [SHR], 0.73; 95% CI, 0.59-0.89) and mortality (HR, 0.68; 95% CI, CI 0.58-0.81). In time-updated analyses, participants with eGFRdiffcys-cr less than -15 mL/min/1.73 m2 had higher risks of ESKD (SHR, 1.83; 95% CI, 1.10-3.04) and mortality (HR, 3.03; 95% CI, 2.19-4.19) compared with participants with similar eGFRcys and eGFRcr. Conversely, participants with eGFRdiffcys-cr of 15 mL/min/1.73 m2 or greater had lower risks of ESKD (SHR, 0.50; 95% CI, 0.35-0.71) and mortality (HR, 0.58; 95% CI, 0.45-0.75). Longitudinal changes in eGFRdiffcys-cr were associated with mortality risk. Compared with participants who had similar slopes by eGFRcys and eGFRcr, those with smaller eGFRcr declines had an 8-fold increased mortality risk (HR, 8.20; 95% CI, 6.37-10.56), and those with larger apparent declines by eGFRcr had a lower mortality risk (HR, 0.14; 95% CI, 0.08-0.24).

Conclusions and Relevance

These findings suggest that large differences between eGFRcys and eGFRcr were common in persons with CKD. These differences and their changes over time may be informative of ESKD and mortality risks, warranting monitoring of both eGFRcys and eGFRcr in this high-risk population.

Perceptions of Older Men Using a Mobile Health App to Monitor Lower Urinary Tract Symptoms and Tamsulosin Side Effects: Mixed Methods Study

Background

Mobile health (mHealth) apps may provide an efficient way for patients with lower urinary tract symptoms (LUTS) to log and communicate symptoms and medication side effects with their clinicians.

Objective

The aim of this study was to explore the perceptions of older men with LUTS after using an mHealth app to track their symptoms and tamsulosin side effects.

Methods

Structured phone interviews were conducted after a 2-week study piloting the daily use of a mobile app to track the severity of patient-selected LUTS and tamsulosin side effects. Quantitative and qualitative data were considered.

Results

All 19 (100%) pilot study participants completed the poststudy interviews. Most of the men (n=13, 68%) reported that the daily questionnaires were the right length, with 32% (n=6) reporting that the questionnaires were too short. Men with more severe symptoms were less likely to report changes in perception of health or changes in self-management; 47% (n=9) of the men reported improved awareness of symptoms and 5% (n=1) adjusted fluid intake based on the questionnaire. All of the men were willing to share app data with their clinicians. Thematic analysis of qualitative data yielded eight themes: (1) orientation (setting up app, format, symptom selection, and side-effect selection), (2) triggers (routine or habit and symptom timing), (3) daily questionnaire (reporting symptoms, reporting side effects, and tailoring), (4) technology literacy, (5) perceptions (awareness, causation or relevance, data quality, convenience, usefulness, and other apps), (6) self-management, (7) clinician engagement (communication and efficiency), and (8) improvement (reference materials, flexibility, language, management recommendations, and optimize clinician engagement).

Conclusions

We assessed the perceptions of men using an mHealth app to monitor and improve management of LUTS and medication side effects. LUTS management may be further optimized by tailoring the mobile app experience to meet patients’ individual needs, such as tracking a greater number of symptoms and integrating the app with clinicians’ visits. mHealth apps are likely a scalable modality to monitor symptoms and improve care of older men with LUTS. Further study is required to determine the best ways to tailor the mobile app and to communicate data to clinicians or incorporate data into the electronical medical record meaningfully.

Tracking Lower Urinary Tract Symptoms and Tamsulosin Side Effects Among Older Men Using a Mobile App (PERSONAL): Feasibility and Usability Study

Background

Continuous α1a-blockade is the first-line treatment for lower urinary tract symptoms (LUTS) among older men with suspected benign prostatic hyperplasia. Variable efficacy and safety for individual men necessitate a more personalized, data-driven approach to prescribing and deprescribing tamsulosin for LUTS in older men.

Objective

We aim to evaluate the feasibility and usability of the PERSONAL (Placebo–Controlled, Randomized, Patient-Selected Outcomes, N-of-1 Trials) mobile app for tracking daily LUTS severity and medication side effects among older men receiving chronic tamsulosin therapy.

Methods

We recruited patients from the University of California, San Francisco health care system to participate in a 2-week pilot study. The primary objectives were to assess recruitment feasibility, study completion rates, frequency of symptom tracking, duration of tracking sessions, and app usability rankings measured using a follow-up survey. As secondary outcomes, we evaluated whether daily symptom tracking led to changes in LUTS severity, perceptions of tamsulosin, overall quality of life, medication adherence between baseline and follow-up surveys, and perceived app utility.

Results

We enrolled 19 men within 23 days, and 100% (19/19) of the participants completed the study. Each participant selected a unique combination of symptoms to track and recorded data in the PERSONAL app, with a median daily completion rate of 79% (11/14 days). The median duration of the app session was 44 (IQR 33) seconds. On a scale of 1 (strongly disagree) to 5 (strongly agree), the participants reported that the PERSONAL app was easy to use (mean 4.3, SD 1.0), that others could learn to use it quickly (mean 4.2, SD 0.9), and that they felt confident using the app (mean 4.4, SD 0.8). LUTS severity, quality of life, and medication adherence remained unchanged after the 2-week study period. Fewer men were satisfied with tamsulosin after using the app (14/19, 74% vs 17/19, 89% at baseline), although the perceived benefit from tamsulosin remained unchanged (18/19, 95% at baseline and at follow-up). In total, 58% (11/19) of the participants agreed that the PERSONAL app could help people like them manage their urinary symptoms.

Conclusions

This pilot study demonstrated the high feasibility and usability of the PERSONAL mobile app to track patient-selected urinary symptoms and medication side effects among older men taking tamsulosin to manage LUTS. We observed that daily symptom monitoring had no adverse effects on the secondary outcomes. This proof-of-concept study establishes a framework for future mobile app studies, such as digital n-of-1 trials, to collect comprehensive individual-level data for personalized LUTS management in older men.

Association of plant-based diet index with prostate cancer risk

BACKGROUND

Plant-based diets are associated with multiple health benefits and a favorable environmental impact. For prostate cancer, previous studies suggest a beneficial role of specific plant-based foods (e.g., tomatoes) and a potentially harmful role of specific animal-based foods (e.g., meat, dairy). However, less is known about plant-based dietary patterns.

OBJECTIVES

We sought to examine the relation between plant-based diet indices and prostate cancer risk, including clinically relevant disease.

METHODS

This was a prospective cohort study including 47,239 men in the Health Professionals Follow-Up Study (1986-2014). Overall and healthful plant-based diet indices were calculated from FFQs. Cox proportional hazards models were used to estimate HRs and 95% CIs to examine the risk of incident prostate cancer (total and by clinical category), among men ages <65 and ≥65 y.

RESULTS

Of the 47,239 men, 6655 men were diagnosed with prostate cancer over follow-up, including 515 with advanced-stage disease at diagnosis, 956 with lethal disease (metastasis or death), and 806 prostate cancer deaths. Greater overall plant-based consumption was associated with a significantly lower risk of fatal prostate cancer (HR: 0.81; 95% CI: 0.64, 1.01; P-trend = 0.04). In men aged <65, a higher plant-based diet index was associated with a lower risk of advanced, lethal, and fatal prostate cancer. Moreover, greater consumption of a healthful plant-based diet was associated with lower risks of total (HR: 0.84; 95% CI: 0.73, 0.98; P-trend = 0.046) and lethal prostate cancer (HR: 0.56; 95% CI: 0.34, 0.94; P-trend = 0.03) at age <65. There were no associations between overall or healthful plant-based diet indices with prostate cancer among men ≥65 y. Fewer than 1% of participants followed a strict vegetarian or vegan diet.

CONCLUSIONS

This prospective study provides supportive evidence that greater consumption of healthful plant-based foods is associated with a lower risk of aggressive forms of prostate cancer, with stronger benefit among men aged <65 y.

Assessment of Frailty and Association With Progression of Benign Prostatic Hyperplasia Symptoms and Serious Adverse Events Among Men Using Drug Therapy

IMPORTANCE

Benign prostatic hyperplasia (BPH) in older men can cause lower urinary tract symptoms (LUTS), which are increasingly managed with medications. Frailty may contribute to both symptom progression and serious adverse events (SAEs), shifting the balance of benefits and harms of drug therapy.

OBJECTIVE

To assess the association between a deficit accumulation frailty index and clinical BPH progression or SAE.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the Medical Therapy of Prostatic Symptoms trial, which compared placebo, doxazosin, finasteride, and combination therapy in men with moderate-to-severe LUTS, reduced urinary flow rate, and no prior BPH interventions, hypotension, or elevated prostate-specific antigen. Enrollment was from 1995 to 1998, and follow-up was through 2001. Data were assessed in February 2021.

EXPOSURES

A frailty index (score range, 0-1) using 68 potential deficits collected at baseline was used to categorized men as robust (score ≤0.1), prefrail (score 0.1 to <0.25), or frail (score ≥0.25).

MAIN OUTCOMES AND MEASURES

Primary outcomes were time to clinical BPH progression and time to SAE, as defined in the parent trial. Adjusted hazard ratios (AHRs) were estimated using Cox proportional hazards regressions adjusted for demographic variables, treatment group, measures of obstruction, and comorbidities.

RESULTS

Among 3047 men (mean [SD] age, 62.6 [7.3] years; range, 50-89 years) in this analysis, 745 (24%) were robust, 1824 (60%) were prefrail, and 478 (16%) were frail at baseline. Compared with robust men, frail men were older (age ≥75 years, 12 men [2%] vs 62 men [13%]), less likely to be White (646 men [87%] vs 344 men [72%]), less likely to be married (599 men [80%] vs 342 men [72%]), and less likely to have 16 years or more of education (471 men [63%] vs 150 men [31%]). During mean (SD) follow-up of 4.0 (1.5) years, the incidence rate of clinical BPH progression was 2.2 events per 100 person-years among robust men, 2.9 events per 100 person-years among prefrail men (AHR, 1.36; 95% CI, 1.02-1.83), and 4.0 events per 100 person-years among frail men (AHR, 1.82; 95% CI, 1.24-2.67; linear P = .005). Larger point estimates were seen among men who received doxazosin or combination therapy, although the test for interaction between frailty index and treatment group did not reach statistical significance (P for interaction = .06). Risk of SAE was higher among prefrail and frail men (prefrail vs robust AHR, 1.81; 95% CI, 1.48-2.23; frail vs robust AHR, 2.86; 95% CI, 2.21-3.69; linear P < .001); this association was similar across treatment groups (P for interaction = .76).

CONCLUSIONS AND RELEVANCE

These findings suggest that frailty is independently associated with greater risk of both clinical BPH progression and SAEs. Older frail men with BPH considering initiation of drug therapy should be counseled regarding their higher risk of progression despite combination therapy and their likelihood of experiencing SAEs regardless of treatment choice.

Lower urinary tract symptoms are associated with musculoskeletal pain among older men: Preliminary evidence for central sensitization as a mechanism?

AIMS

Features of central sensitization (CS) are present in almost all chronic pain conditions, including painful urinary conditions and back pain. Recently CS was proposed as a mechanism of nonpainful lower urinary tract symptoms (LUTS). Using musculoskeletal pain as an indicator of CS, we investigated whether the prevalence of musculoskeletal pain is greater among community-dwelling men with moderate or severe LUTS compared to those with mild LUTS.

METHODS

We conducted a cross-sectional study of 5966 men ≥65 years who attended the Osteoporotic Fractures in Men Study baseline visit. LUTS were assessed with the American Urological Association Symptom Index (AUA-SI) and categorized as none/mild (0-7), moderate (8-19), or severe (≥20). Self-reported back, neck, hip, or knee pain within the 12 months before baseline was categorized as any pain and multilocation pain. We tested our hypothesis using odds ratios (OR) and 95% confidence intervals (CI) estimated from multivariable logistic regression models.

RESULTS

The adjusted odds of any pain were higher among men with moderate (OR 1.49, 95% CI: 1.29-1.72) and severe LUTS (OR 1.76, 95% CI: 1.28-2.40) compared to those with no/mild LUTS. The adjusted odds of pain at ≥ 2 locations were 69% higher among men with moderate (OR 1.69, 95% CI: 1.45-196) and more than double among men with severe LUTS (OR 2.24, 95% CI: 1.62-3.10) compared to men with no/mild LUTS.

CONCLUSIONS

Musculoskeletal pain, especially at multiple locations, is associated with greater LUTS severity among older men. CS may represent a novel shared mechanism of pain and LUTS.

Longitudinal Changes in Adiposity and Lower Urinary Tract Symptoms Among Older Men

BACKGROUND

Adiposity increases risk for male lower urinary tract symptoms (LUTS), although longitudinal studies have produced conflicting results. No prior studies have evaluated longitudinal associations of changes in adiposity with concurrent LUTS severity among older men.

METHODS

We used repeated adiposity measurements from dual-energy x-ray absorptiometry (DXA), body mass index (BMI), and American Urological Association Symptom Index (AUASI) measured at four study visits over a 9-year period among 5949 men enrolled in the Osteoporotic Fractures in Men (MrOS) study. Linear mixed effect models adjusted for age, health-related behaviors, and comorbidities were created to evaluate the association between baseline and change in visceral adipose tissue (VAT) area, total fat mass, and BMI with change in LUTS severity measured by the AUASI.

RESULTS

A non-linear association was observed between baseline VAT area and change in AUASI: men in baseline VAT tertile (T) 2 had a lower annual increase in AUASI score compared to men in T1 and T3 (T2 versus T1: β=-0.07; 95% CI -0.12, -0.03; P= 0.008; T3 versus T1: NS) but differences were small. No significant associations were observed between change in VAT area and change in AUASI score. Neither baseline tertiles nor change in total fat mass or BMI were associated with change in AUASI score.

CONCLUSIONS

Changes in VAT area, total fat mass, and BMI were not associated with change in LUTS severity in this cohort. Thus, despite other health benefits, interventions targeting adiposity alone are unlikely to be effective for preventing or treating LUTS among older men.

Physical Activity, Diet, and Incident Urinary Incontinence in Postmenopausal Women: Women's Health Initiative Observational Study

BACKGROUND

Physical activity and macronutrient intake, important contributors to energy balance, may be independently associated with female urinary incontinence (UI).

METHODS

We evaluated the association of baseline self-reported physical activity and macronutrient intake, via food-frequency questionnaire, with incident UI subtypes after 3 years among 19,741 post-menopausal women in the Women's Health Initiative Observational Study. Odds ratios (OR) for incident urgency, stress, and mixed UI were calculated using multivariable logistic regression.

RESULTS

Women who reported total physical activity (MET-hours/week) ≥30 vs <0.1 were 16% less likely to develop urgency UI (OR=0.84; 95% CI 0.70, 1.00) and 34% less likely for mixed UI (OR=0.66; 0.46, 0.95), although linear trends were no longer statistically significant after adjusting for baseline weight and weight change (P-trend=0.15 and 0.16, respectively). The association between physical activity and incident stress UI was less consistent. Higher uncalibrated protein intake was associated with increased odds of incident urgency UI (≥19.4% versus <14.1% of energy intake OR=1.14; 95% CI 0.99, 1.30; P-trend=0.02), while confidence intervals were wide and included 1.0 for calibrated protein intake. Other macronutrients were not associated with urgency UI and macronutrient intake was not associated with incident stress or mixed UI (P-trend>0.05 for all).

CONCLUSIONS

Among post-menopausal women, higher physical activity was associated with lower risk of incident urgency and mixed UI, but not stress UI, independent of baseline weight and weight change. Higher protein intake was associated with increase urgency UI, but no associations were observed between other macronutrient and UI subtypes.

Leveraging innovative technology to generate drug response phenotypes for the advancement of biomarker-driven precision dosing

Although traditional approaches to biomarker discovery have elucidated key molecular markers that have improved drug selection (precision medicine), the discovery of biomarkers that inform optimal dose selection (precision dosing) continues to be a challenge in many therapeutic areas. Larger and more diverse study populations are necessary to discover additional biomarkers that provide the resolution needed for a more tailored dose. To generate and accommodate large datasets of drug response phenotypes, time- and cost-efficient strategies are necessary. In particular, a multitude of technological advances that originated for purposes outside of biomedical research (electronic health records, direct-to-consumer genetic testing, social media, mobile devices, and machine learning) have made it easier to communicate, connect, and gather information from consumers. Although these technologies have been used with success in the health sciences for an array of purposes, these resources have not been fully capitalized on for precision dosing. This perspective will touch on how these innovations can be used as data sources, data collection tools, and data processing tools for drug-response phenotypes with a unique focus on advancing biomarker-driven precision dosing.

Co-Occurrence of Lower Urinary Tract Symptoms and Frailty among Community-Dwelling Older Men

BACKGROUND/OBJECTIVES

To estimate associations between lower urinary tract symptoms (LUTS) and phenotypic frailty in older men.

DESIGN

Cross-sectional study.

SETTING

Community-dwelling men recruited from 2000 to 2002 from six U.S. academic centers for the Osteoporotic Fractures in Men Study.

PARTICIPANTS

A total of 5,979 men aged 65 and older.

MEASUREMENTS

The independent variable was LUTS severity (none/mild, moderate, or severe) assessed with the American Urologic Association Symptom Index. Participants were categorized as frail, intermediate stage, or robust using an adapted Cardiovascular Health Study index (components: low lean mass, weakness, exhaustion, slowness, and low physical activity). Associations were estimated with odds ratios and 95% confidence intervals (CIs) from multivariable multinomial logistic regression models adjusted for potential confounders of age, other demographics, health-related behaviors, and comorbidities.

RESULTS

The prevalence of frailty was 7%, 11%, and 18% among men with none/mild, moderate, and severe LUTS, respectively. Moderate and severe LUTS, overall and by storage and voiding subscores, were associated with higher odds of both intermediate stage and frailty in all models. After adjustment for confounders, the odds of frailty was 1.41 times higher among men with moderate LUTS (95% CI = 1.14-1.74) and 2.51 times higher among men with severe LUTS (95% CI = 1.76-3.55), compared with none/mild LUTS. Severe LUTS was associated with a greater odds of individual frailty components exhaustion and low physical activity.

CONCLUSION

The prevalence of phenotypic frailty is higher among older community-dwelling men with moderate or severe LUTS compared with those with mild or no LUTS. The positive association between LUTS severity and frailty among older men appears independent of age and known frailty risk factors. Although the temporal direction of this association and the utility of LUTS or frailty interventions in this population remain unclear, the high co-occurrence of these conditions could lead to earlier identification of frailty when clinically appropriate.

Association of Lower Urinary Tract Symptom Severity with Kidney Function among Community Dwelling Older Men

PURPOSE

Most international practice guidelines recommend screening for chronic kidney disease among older men with lower urinary tract symptoms. However, prior studies supporting these guidelines are insufficient due to incomplete assessments of kidney function and inadequate adjustment for confounding factors.

MATERIALS AND METHODS

We conducted a cross-sectional study among 5,530 American men older than 65 years in the multicenter Osteoporotic Fractures in Men Study. Chronic kidney disease was defined per international guidelines as estimated glomerular filtration rate less than 60 ml/minute/1.73 m2 based on serum creatinine or cystatin C, or urinary albumin-to-creatinine ratio 30 mg/gm or greater. Lower urinary tract symptoms were assessed with the American Urological Association Symptom Index. Associations were estimated using multivariable linear and modified Poisson regression models.

RESULTS

Chronic kidney disease prevalence was 16% among 5,530 men with serum creatinine, 24% among 1,504 men with serum cystatin C and 14% among 1,487 men with urinary albumin-to-creatinine measurements. Lower urinary tract symptoms were not associated with lower estimated glomerular filtration rate based on serum creatinine or cystatin C. Although symptom severity was modestly associated with a higher prevalence of chronic kidney disease in age/site adjusted analyses, confidence intervals were wide and associations using all 3 definitions were not statistically significant after adjustment for important confounders, including cardiovascular disease and analgesic use.

CONCLUSIONS

Lower urinary tract symptoms are not independently associated with multiple measures of kidney dysfunction or prevalence of chronic kidney disease among older community dwelling men. Our results do not support recommendations for kidney function testing among older men with lower urinary tract symptoms.

Association of Diet With Erectile Dysfunction Among Men in the Health Professionals Follow-up Study

IMPORTANCE

Erectile dysfunction, especially in younger men, is an early sign of cardiovascular disease and may decrease quality of life. Men may be motivated to adopt a healthy dietary pattern if it lowers their risk of erectile dysfunction.

OBJECTIVE

To assess the association between adherence to a diet quality index based on healthy dietary patterns and erectile dysfunction in men.

DESIGN, SETTING, AND PARTICIPANTS

This population-based prospective cohort study included men from the Health Professionals Follow-up Study with follow-up from January 1, 1998, through January 1, 2014. Participants included US male health professionals aged 40 to 75 years at enrollment. Men with erectile dysfunction or a diagnosis of myocardial infarction, diabetes, stroke, or genitourinary cancer at baseline were excluded. Analyses were completed in February 2020.

EXPOSURES

A food frequency questionnaire was used to determine nutrient and food intake every 4 years.

MAIN OUTCOMES AND MEASURES

Diet quality was assessed by Mediterranean Diet score and the Alternative Healthy Eating Index 2010 score, with higher scores indicating healthier diet. Dietary index scores were cumulatively updated from 1986 until men developed erectile dysfunction, cardiovascular disease, died, or were lost to follow-up. Incident erectile dysfunction was assessed with questionnaires in 2000, 2004, 2008, and 2012. Hazard ratios (HRs) by prespecified categories or quintiles of dietary index scores were estimated using Cox proportional hazards regression analyses stratified by age.

RESULTS

Among 21 469 men included in analysis, mean (SD) age at baseline was 62 (8.4) years. During a mean (SD) follow-up of 10.8 (5.4) years and 232 522 person-years, there were 968 incident erectile dysfunction cases among men younger than 60 years, 3703 cases among men aged 60 to less than 70 years, and 4793 cases among men aged 70 years or older. Men younger than 60 years and in the highest category of the Mediterranean Diet score had the lowest relative risk of incident erectile dysfunction compared with men in the lowest category (HR, 0.78; 95% CI, 0.66-0.92). Higher Mediterranean diet scores were also inversely associated with incident erectile dysfunction among older men (age 60 to <70 years: HR, 0.82; 95% CI, 0.76-0.89; age ≥70 years: HR, 0.93; 95% CI, 0.86-1.00). Men scoring in the highest quintile of the Alternative Healthy Eating Index 2010 also had a lower risk of incident erectile dysfunction, particularly among men age younger than 60 years (quintile 5 vs quintile 1: HR, 0.78; 95% CI, 0.63-0.97).

CONCLUSIONS AND RELEVANCE

This cohort study found that adherence to healthy dietary patterns was associated with a lower risk for erectile dysfunction, suggesting that a healthy dietary pattern may play a role in maintaining erectile health.

Association Between Lower Urinary Tract Symptoms and Frailty in Older Men Presenting for Urologic Care

OBJECTIVE

To evaluate the association between non-neurogenic lower urinary tract symptoms (LUTS) and frailty among treatment-seeking older men.

METHODS

This is a cross-sectional study of male patients age 65 years and older presenting to an academic urology practice between December 2015 and March 2019. Men with cancer, neurologic disease, indwelling catheter, or continuous leakage were excluded. Participants completed a Timed-Up-and-Go-Test (TUGT) which was used to categorize men as fast (≤10 seconds), intermediate (11-14 seconds), or slow (≥15 seconds). Participants with the following diagnoses were identified using billing codes extracted from the electronic medical record: overactive bladder (OAB), benign prostatic hyperplasia (BPH), mixed OAB/BPH, or non-LUTS urologic condition. Multivariable associations were evaluated using multinomial logistic regression models adjusted for age, race, and body mass index.

RESULTS

Among 2206 men included in our sample, 64% were fast (mean TUGT time: 8.3 ± 1.2 seconds), 25% were intermediate (mean TUGT time: 12.0 ± 1.0 seconds), and 11% were slow (mean TUGT time: 18.5 ± 4.7 seconds). Subjects with slow TUGT times were more likely to be older, non-White, and have LUTS. Compared to non-LUTS conditions, OAB (odds ratio [OR] = 2.62, 95% CI 1.74, 3.93), BPH (OR = 1.70, 95% 1.14, 2.55), and mixed OAB/BPH (OR = 1.82, 95% 1.14, 2.92) were all associated with increased odds of slow TUGT time. LUTS diagnosis was not significantly associated with intermediate TUGT time.

CONCLUSION

LUTS diagnosis, particularly OAB, is associated with increased odds of slow TUGT time, a surrogate of frailty, compared to non-LUTS conditions. Frailty is common among older men with LUTS and should be considered during the initial urological evaluation.

PERSONAL: Feasibility Study Protocol for Placebo-Controlled, Randomized n-of-1 Trials of Tamsulosin for Lower Urinary Tract Symptoms

Background: Lower urinary tract symptoms (LUTS) affect more than half of men over age 70 and contribute to both poor health-related quality of life and polypharmacy. Tamsulosin hydrochloride, a selective α₁-blocker, is the most common medication used to treat LUTS due to presumed benign prostatic hyperplasia and is often prescribed indefinitely, although not all men benefit from long-term therapy. N-of-1 trials allow for individualized estimates of benefit and harm and could facilitate decisions regarding chronic tamsulosin therapy for LUTS, particularly among older men. Our team developed the PERSONAL (PlacEbo-controlled, Randomized, patient-Selected Outcomes, N-of-1 triALs) app to track daily urinary symptoms and medication side effects for n-of-1 trials among older men with LUTS.

Materials and Methods: We will conduct a feasibility study of 20 individual randomized n-of-1 trials using the PERSONAL app to compare tamsulosin (0.4 or 0.8 mg) vs. placebo among older men taking tamsulosin for LUTS. We will include men over age 65 with a smartphone for whom temporary discontinuation of tamsulosin is safe, (e.g., no history of acute retention). Participants will work with research staff to prospectively identify the most important urinary symptoms and medication side effects that they would like to digitally track. Men will then be randomized to 2-week treatment periods of tamsulosin or placebo followed by a 1-week wash-out with placebo, for 4 distinct treatment periods and 3 wash-out periods, totaling 11 weeks. Study medications will be blinded using over-encapsulation of tamsulosin pills and matching placebo. Our primary outcomes for this study will be recruitment and retention of eligible men, completion rates of n-of-1 trials and daily questionnaires using the PERSONAL app, and participants' perceived usefulness of their n-of-1 trial for determining whether tamsulosin is effective for them. Linear mixed effects models with individual-specific intercepts and intervention effects will also be used to estimate within-individual effects of tamsulosin.

Discussion: The goal of this innovative study is to establish feasibility and acceptability of using a mobile health app and n-of-1 trials to provide older men with individualized estimates of benefits and harms of chronic tamsulosin therapy for LUTS.

Mediterranean diet after prostate cancer diagnosis and urinary and sexual functioning: The health professionals follow-up study

BACKGROUND

Men with prostate cancer often experience urinary and sexual dysfunction after treatment. Previous studies have demonstrated a relationship between dietary factors and these symptoms among men with diabetes or metabolic syndrome. However, there are limited data on whether diet after prostate cancer diagnosis, including a Mediterranean dietary pattern, affects urinary and sexual function among prostate cancer survivors.

METHODS

Men diagnosed with non-metastatic prostate cancer in the Health Professionals Follow-up Study (n = 2960) from 1986 to 2012 were prospectively followed for a median of 8.3 years after treatment. Participants completed validated dietary questionnaires every 4 years and a health-related quality of life assessment in 2010 or 2012. We used generalized linear models to examine associations between post-diagnosis Mediterranean Diet Score (including individual score components and dietary fat subtypes) and quality of life domains (sexual functioning, urinary irritation/obstruction, urinary incontinence) assessed using the Expanded Prostate Cancer Index Composite Short Form (score 0-100; higher scores indicate better function).

RESULTS

No statistically significant relationships were observed between the Mediterranean Diet Score after prostate cancer diagnosis and urinary or sexual function. However, the associations did vary depending on pre-diagnosis urinary and sexual dysfunction for urinary irritation/obstruction and sexual function scores, respectively (P-interactions < 0.0001). Men with higher post-diagnosis vegetable intake reported higher urinary incontinence scores (72 vs 76 comparing lowest to highest quintile; P-trend = 0.003). Similarly, higher vegetable intake and lower polyunsaturated fat intake were associated with higher urinary irritation/obstruction scores (vegetable: 80 vs 84 comparing lowest to highest quintile, P-trend = 0.01; polyunsaturated fat: 84 vs 78 comparing lowest to highest quintile, P-trend = 0.005), however these associations were observed only among men with urinary symptoms prior to their prostate cancer diagnosis.

CONCLUSIONS

Among men with prostate cancer, diet intake after diagnosis was not significantly associated with urinary or sexual function, although some relationships appeared to differ among men with and without symptoms prior to their prostate cancer diagnosis. Higher vegetable intake and lower polyunsaturated fat intake after prostate cancer diagnosis may be associated with better urinary function. However, this analysis was exploratory, and further research is needed to better delineate these relationships and guide dietary recommendations for men with prostate cancer.

Predictors of higher-risk chronic opioid prescriptions in an academic primary care setting

BACKGROUND

Patients with chronic noncancer pain treated with higher doses of opioids or concurrent substance use are at increased risk of adverse events. Although several national guidelines recommend maximum dosing thresholds and urine drug testing, adherence to these guidelines is inconsistent.

METHODS

To identify predictors of higher-risk opioid prescriptions in 2 academic primary care clinics, the authors developed a retrospective cohort of 842 patients who were prescribed ≥5 opioid prescriptions for noncancer pain between March 2012 and March 2013. The authors evaluated odds of higher-dose opioid prescriptions and urine drug testing using multivariate logistic models.

RESULTS

Among study subjects, 47% received prescriptions for the equivalent of ≥50 mg morphine per day. After adjustment for confounders, patients with a resident primary care provider were less likely to receive higher-dose prescriptions compared with faculty providers (odds ratio = 0.66, 95% confidence interval [CI]: 0.46-0.94), whereas patients with a nonlocal home address were more likely to be prescribed higher doses (odds ratio = 2.1, 95% CI: 1.5-2.9). Hispanic, Asian, and older patients were also less likely to be prescribed higher doses. Urine drug testing was not regularly completed (35% over 2 years), but odds of testing were higher for patients who self-identified as black, had resident primary care providers, lived locally, or were prescribed higher opioid doses.

CONCLUSIONS

In this academic clinical setting, patients with a resident primary care provider are less likely to receive higher-risk opioid prescriptions, as are Hispanic, Asian, and older patients. Black patients complete urine drug tests more frequently independent of other patient and provider characteristics. Additional studies are needed to assess why patients who travel larger distances to their primary care clinic are prescribed higher doses of opioids for chronic noncancer pain.

Geographic Disparities in Access to Agencies Providing Income-Related Social Services

Geographic location is an important factor in understanding disparities in access to health-care and social services. The objective of this cross-sectional study is to evaluate disparities in the geographic distribution of income-related social service agencies relative to populations in need within Boston. Agency locations were obtained from a comprehensive database of social services in Boston. Geographic information systems mapped the spatial relationship of the agencies to the population using point density estimation and was compared to census population data. A multivariate logistic regression was conducted to evaluate factors associated with categories of income-related agency density. Median agency density within census block groups ranged from 0 to 8 agencies per square mile per 100 population below the federal poverty level (FPL). Thirty percent (n = 31,810) of persons living below the FPL have no access to income-related social services within 0.5 miles, and 77 % of persons living below FPL (n = 83,022) have access to 2 or fewer agencies. 27.0 % of Blacks, 30.1 % of Hispanics, and 41.0 % of non-Hispanic Whites with incomes below FPL have zero access. In conclusion, some neighborhoods in Boston with a high concentration of low-income populations have limited access to income-related social service agencies.

Selenoprotein and antioxidant genes and the risk of high-grade prostate cancer and prostate cancer recurrence

BACKGROUND

Observational studies suggest an inverse association between selenium and risk of prostate cancer. However, randomized controlled trials of selenium supplementation have reported conflicting results. Thus, we examined plasma selenium and selenium-related genes in relation to risk of high-grade prostate cancer and prostate cancer recurrence among men initially diagnosed with non-metastatic disease.

METHODS

We measured plasma selenium and genotyped 73 single nucleotide polymorphisms in TXNRD1, TXNRD2, GPX1, GPX3, GPX4, SEP15, SEPP1, SELENBP1, OGG1, and CAT among 568 men with non-metastatic prostate cancer who underwent radical prostatectomy. We examined associations between plasma selenium, genotypes, and risk of high-grade prostate cancer (Gleason grade ≥8 or 7 with primary score ≥4; n = 111) using logistic regression, and risk of prostate cancer recurrence (61 events; 3.8 y median follow-up) using Cox proportional hazards regression.

RESULTS

Plasma selenium was not associated with risk of high-grade prostate cancer or prostate cancer recurrence. Less common alleles of rs11913319 in TXNRD2 and rs125701 in OGG1 were associated with an increased risk of high-grade prostate cancer. We observed associations between the risk of prostate cancer recurrence and multiple SNPs in TXNRD1, TXNRD2, GPX3, and SEP15. These associations were no longer statistically significant after adjustment for multiple comparisons.

CONCLUSIONS

Among men with non-metastatic prostate cancer, there is suggestive evidence that genetic variation in selenoproteins and related antioxidant enzymes may be associated with risk of high-grade disease at diagnosis and prostate cancer recurrence.

Antioxidant and vitamin E transport genes and risk of high-grade prostate cancer and prostate cancer recurrence

BACKGROUND

Observational studies suggest an inverse association between vitamin E and risk of prostate cancer, particularly aggressive tumors. However, three large randomized controlled trials have reported conflicting results. Thus, we examined circulating vitamin E and vitamin E-related genes in relation to risk of high-grade prostate cancer and prostate cancer recurrence among men initially diagnosed with clinically organ-confined disease.

METHODS

We measured circulating α- and γ-tocopherol and genotyped 30 SNPs in SOD1, SOD2, SOD3, TTPA, and SEC14L2 among 573 men with organ-confined prostate cancer who underwent radical prostatectomy. We examined associations between circulating vitamin E, genotypes, and risk of high-grade prostate cancer (Gleason grade ≥ 8 or 7 with primary score ≥ 4; n = 117) using logistic regression, and risk of recurrence (56 events; 3.7 years median follow-up) using Cox proportional hazards regression.

RESULTS

Circulating γ-tocopherol was associated with an increased risk of high-grade prostate cancer (Q4 v. Q1 odds ratio [OR] = 1.87; 95% confidence intervals [CI]: 0.97-3.58; P trend =0.02). The less common allele in SOD3 rs699473 was associated with an increased risk of high-grade disease (T > C: OR = 1.40, 95% CI: 1.04-1.89). Two independent SNPs in SOD1 were inversely associated with prostate cancer recurrence in additive models (rs17884057 hazard ratio [HR] = 0.49, 95%CI: 0.25-0.96; rs9967983 HR = 0.62, 95% CI: 0.40-0.95).

CONCLUSIONS

Among men with clinically organ-confined prostate cancer, genetic variation in SOD may be associated with risk of high-grade disease at diagnosis and disease recurrence. Circulating γ-tocopherol levels may also be associated with an increased risk of high-grade disease at diagnosis.

Plasma vitamin D levels, menopause, and risk of breast cancer: dose-response meta-analysis of prospective studies

Previous evidence suggests that higher circulating 25-hydroxyvitamin D (25[OH]D) levels are variably associated with lower breast cancer risk; however, prospective studies and clinical trials have been inconsistent, particularly between older and younger women of differing menopausal status. We conducted a quantitative nonlinear dose-response meta-analysis of prospective studies evaluating the association between circulating 25(OH)D and breast cancer risk, stratified by menopause. A systematic search of MEDLINE and EMBASE included studies published through May 2011. We reviewed references from retrieved articles and contacted relevant investigators for additional data from prospective studies on circulating 25(OH)D levels and incident breast cancers. Prospective studies of circulating vitamin D and breast cancer risk were reviewed, and no language restrictions were imposed. Information on study population, menopausal status, 25(OH)D levels, and relative risk (RR) estimates were extracted using a standardized protocol.A total of 9 prospective studies were included, comprising 5206 cases and 6450 controls. Data were pooled using dose-response random-effects meta-regression models. Identifying nonlinear effects, spline models were optimized for thresholds. The relationship between circulating 25(OH)D and breast cancer risk differed by menopausal status (p = 0.05 for effect modification). While no association was found in premenopausal women, dose-response modeling revealed a nonlinear inverse association among postmenopausal women. Notably, a flat association was observed in the lowest range of 25(OH)D levels <27 ng/mL (RR = 1.01 per 5 ng/mL; 95% confidence interval [CI], 0.98-1.04). In contrast, postmenopausal breast cancer risk decreased with 25(OH)D levels 27-<35 ng/mL (p = 0.02 for nonlinear risk change), where a 5 ng/mL increase in 25(OH)D was associated with a 12% lower risk of breast cancer (RR = 0.88 per 5 ng/mL; 95% CI, 0.79-0.97), with suggestive flattening at higher doses >35 ng/mL. The significant inverse association did not appear to vary across strata of invasive/in-situ cases, body mass index adjustment, region, postmenopausal hormone use, or assay method.In summary, this dose-response meta-analysis of prospective studies of plasma 25(OH)D suggested a breast cancer risk differential by menopause, whereby a step-wise inverse association was observed beyond a threshold of 27 ng/mL, but with flattening of effects above 35 ng/mL, in postmenopausal women. These findings help resolve prior inconsistent findings and may carry important clinical and public health implications.

Abstract 77: Analgesic use in relation to sex hormone and prolactin concentrations in premenopausal women

The use of common analgesics, such as aspirin, non-aspirin NSAIDs and acetaminophen, may be associated with the risk of several hormone-related cancers, possibly via effects on sex hormone and prolactin concentrations. Therefore, we assessed the cross-sectional relationship between analgesic (aspirin, non-aspirin NSAIDS, and acetaminophen) use and sex hormone and prolactin concentrations among 2,034 premenopausal women, 32 to 54 years old, from the Nurses' Health Study II. Approximately 84% of women provided timed luteal and follicular blood samples; the remainder provided a single untimed sample. After adjustment for age, BMI, parity, and other potential confounders, acetaminophen use was inversely associated with prolactin levels (ptrend= 0.04). Compared to non-users, prolactin concentrations were 11.8% lower among women who reported using acetaminophen at least 2 times per week (p&lt;0.01). Similarly, acetaminophen was inversely associated with free testosterone, when comparing use at least 2 times per week to non-users (7.1% lower, p = 0.04; ptrend= 0.04). Use of non-aspirin NSAIDs was positively associated with follicular free estradiol, with 13.5% higher levels in women who reported use 4 or more days per week as compared to non-users (p = 0.04; ptrend= 0.11); results for free follicular estradiol were similar (13.2% higher, p = 0.06; ptrend= 0.11) though not statistically significant. There were no clear associations observed between analgesic use and luteal estradiol, estrone, estrone sulfate, DHEA, DHEAS, androstenedione, and estrogen/androgen ratios. After adjustment for multiple comparisons, none of the associations were statistically significant. In conclusion, our study provides modest evidence for an association of acetaminophen use with prolactin and free testosterone concentrations in premenopausal women, and the suggestion of an association between non-aspirin NSAIDs and follicular free estradiol among those with frequent use.

Citation Format: Scott R. Bauer, Renee T. Fortner, Margaret A. Gates, Heather Eliassen, Susan E. Hankinson, Shelley S. Tworoger. Analgesic use in relation to sex hormone and prolactin concentrations in premenopausal women. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 77.

Statin use and risk of prostate cancer in the prospective Osteoporotic Fractures in Men (MrOS) Study

BACKGROUND

Statins are a common medication for cholesterol control that may also have effects on cancer-related pathways. The evidence of an association between statins and prostate cancer risk remains ambiguous.

METHODS

We examined statin use in a prospective cohort of 5,069 elderly U.S. men and the risk of incident total, low/high stage, and low/high grade prostate cancer diagnosed between 2000 and 2008. We used multivariate logistic regression models to estimate relative risks and 95% confidence intervals, adjusting for demographic and lifestyle characteristics.

RESULTS

There was no evidence of an association between statin use and any of the prostate cancer endpoints (total, low/high stage, low/high grade prostate cancer), adjusting for age, study site, race, body mass index, marital status, family history of prostate cancer, number of comorbidities, physical activity, and smoking history.

CONCLUSIONS AND IMPACT

In this study of elderly U.S. men, we observed a null association between statin use and risk of prostate cancer.

The TMPRSS2:ERG rearrangement, ERG expression, and prostate cancer outcomes: a cohort study and meta-analysis

BACKGROUND

Whether the genomic rearrangement transmembrane protease, serine 2 (TMPRSS2):v-ets erythroblastosis virus E26 oncogene homolog (ERG) has prognostic value in prostate cancer is unclear.

METHODS

Among men with prostate cancer in the prospective Physicians' Health and Health Professionals Follow-Up Studies, we identified rearrangement status by immunohistochemical assessment of ERG protein expression. We used Cox models to examine associations of ERG overexpression with biochemical recurrence and lethal disease (distant metastases or cancer-specific mortality). In a meta-analysis including 47 additional studies, we used random-effects models to estimate associations between rearrangement status and outcomes.

RESULTS

The cohort consisted of 1,180 men treated with radical prostatectomy between 1983 and 2005. During a median follow-up of 12.6 years, 266 men experienced recurrence and 85 men developed lethal disease. We found no significant association between ERG overexpression and biochemical recurrence [hazard ratio (HR), 0.99; 95% confidence interval (CI), 0.78-1.26] or lethal disease (HR, 0.93; 95% CI, 0.61-1.43). The meta-analysis of prostatectomy series included 5,074 men followed for biochemical recurrence (1,623 events), and 2,049 men followed for lethal disease (131 events). TMPRSS2:ERG was associated with stage at diagnosis [risk ratio (RR)(≥T3 vs. T2), 1.23; 95% CI, 1.16-1.30) but not with biochemical recurrence (RR, 1.00; 95% CI, 0.86-1.17) or lethal disease (RR, 0.99; 95% CI, 0.47-2.09).

CONCLUSIONS

These results suggest that TMPRSS2:ERG, or ERG overexpression, is associated with tumor stage but does not strongly predict recurrence or mortality among men treated with radical prostatectomy.

IMPACT

This is the largest prospective cohort study to examine associations of ERG overexpression and lethal prostate cancer among men treated with radical prostatectomy.

Flavonoid-rich cocoa consumption affects multiple cardiovascular risk factors in a meta-analysis of short-term studies

A growing body of evidence suggests that the consumption of foods rich in polyphenolic compounds, particularly cocoa, may have cardioprotective effects. No review, however, has yet examined the effect of flavonoid-rich cocoa (FRC) on all major cardiovascular risk factors or has examined potential dose-response relationships for these effects. A systematic review and meta-analysis of randomized, controlled trials was performed to evaluate the effect of FRC on cardiovascular risk factors and to assess a dose-response relationship. Inclusion and exclusion criteria as well as dependent and independent variables were determined a priori. Data were collected for: blood pressure, pulse, total cholesterol, HDL cholesterol, LDL cholesterol, TG, BMI, C-reactive protein, flow-mediated vascular dilation (FMD), fasting glucose, fasting insulin, serum isoprostane, and insulin sensitivity/resistance indices. Twenty-four papers, with 1106 participants, met the criteria for final analysis. In response to FRC consumption, systolic blood pressure decreased by 1.63 mm Hg (P = 0.033), LDL cholesterol decreased by 0.077 mmol/L (P = 0.038), and HDL cholesterol increased by 0.046 mmol/L (P = 0.037), whereas total cholesterol, TG, and C-reactive protein remained the same. Moreover, insulin resistance decreased (HOMA-IR: -0.94 points; P < 0.001), whereas FMD increased (1.53%; P < 0.001). A nonlinear dose-response relationship was found between FRC and FMD (P = 0.004), with maximum effect observed at a flavonoid dose of 500 mg/d; a similar relationship may exist with HDL cholesterol levels (P = 0.06). FRC consumption significantly improves blood pressure, insulin resistance, lipid profiles, and FMD. These short-term benefits warrant larger long-term investigations into the cardioprotective role of FRC.

Proton pump inhibitors and risk of fractures: a meta-analysis of 11 international studies

BACKGROUND

Concerns have been raised about the risk of fractures with acid-suppressive medications, such as proton pump inhibitors and histamine(2)-receptor antagonists.

METHODS

This meta-analysis evaluated the association between proton pump inhibitor or histamine(2)-receptor antagonist use and fractures. We performed a systematic search of published literature (1970 to October 10, 2010) in MEDLINE, EMBASE, and other sources. Ten publications reporting 11 studies were considered eligible for analysis.

RESULTS

All studies were observational case-control or cohort studies and primarily evaluated older adults. The summary effect estimate for risk of hip fracture increased modestly among individuals taking proton pump inhibitors (relative risk [RR] 1.30, 95% confidence interval [CI], 1.19-1.43). There also was an increase in spine (RR 1.56, 95% CI, 1.31-1.85) and any-site fractures (RR 1.16, 95% CI, 1.04-1.30) among proton pump inhibitor users. These findings were similar in both men and women and after stratification by duration of use. In contrast, histamine(2)-receptor antagonist use was not significantly associated with increased risk of hip fracture (RR 1.12, 95% CI, 0.97-1.30).

CONCLUSION

In this meta-analysis of observational studies, proton pump inhibitors modestly increased the risk of hip, spine, and any-site fractures, whereas histamine(2)-receptor antagonists were not associated with fracture risk. The possibility of residual confounding cannot be excluded. Further skeletal evaluation should be considered for patients who are taking proton pump inhibitors and also at risk for osteoporotic fracture.

Localization of recombination activating gene 1/green fluorescent protein (RAG1/GFP) expression in secondary lymphoid organs after immunization with T-dependent antigens in rag1/gfp knockin mice

Secondary rearrangements of immunoglobulin gene segments that generate a new antibody repertoire in peripheral B cells have been described as receptor revision and occur by as yet unknown mechanisms. To determine the importance of recombination activating gene (RAG) expression in receptor revision, heterozygous rag1/green fluorescent protein (gfp) knockin mice were used to examine the location of RAG1 expression in the germinal centers (GCs) of lymphoid follicles after immunization with a variety of T-cell-dependent antigens. Immunization of rag1/gfp heterozygous mice or rag1 homozygous knockout mice reconstituted with rag1/gfp heterozygous spleen cells caused the down-regulation of RAG1/GFP signal in GCs. Although some RAG1/GFP(+) cells appeared in regions surrounding the peanut agglutinin (PNA)(+)GL-7(+) GC area, RAG1/GFP(+) cells did not accumulate in the central region. In addition, the stimulation of spleen B cells with anti-mu antibody plus interleukin-4 (IL-4) or with anti-CD40 monoclonal antibody plus IL-7 did not induce GFP signals at detectable levels in vitro. These results clearly demonstrate that RAG1 re-expression either does not occur or is at extremely low levels in antigen-driven B cells in GCs of secondary lymphoid follicles, suggesting that other mechanisms may mediate the gene rearrangements observed in receptor revision.

Interaction of abl and raf with IL-7 signaling pathway and transformation of pre-B cells from resistant mice

After in vivo inoculation with abl/myc- and raf/myc-containing retroviruses, BALB/c mice predominantly develop late stage B cell tumors (plasmacytomas) and less frequently develop earlier B-lineage tumors while DBA/2 mice do not develop B-lineage tumors. We have investigated the in vitro tumorigenic potential of these viruses using cultured normal pre-B cell lymphocytes from both BALB/c and DBA/2 mice. Interestingly, both viruses infect cultured pre-B lymphocytes from both mouse strains. Following infection, IL-7 dependent pre-B cells become independent of normal in vitro growth requirements within 24 h and can rapidly form in vivo pre-B lymphomas in both mouse strains. Mechanisms mediating loss of IL-7 dependence are different depending on whether the raf or abl gene is present in myc-containing viruses. IL-7 JAK-STAT signaling is constitutively active in abl/myc induced pre-B cell tumors. In contrast, IL-7 JAK-STAT signaling is not constitutive in raf/myc induced pre-B cell tumors, demonstrating that subversion of this component of IL-7 signal transduction is not obligatory for pre-B cell transformation or loss of IL-7 dependence.

Modulated expression of the epidermal growth factor-like homeotic protein dlk influences stromal-cell-pre-B-cell interactions, stromal cell adipogenesis, and pre-B-cell interleukin-7 requirements

A close relationship exists between adipocyte differentiation of stromal cells and their capacity to support hematopoiesis. The molecular basis for this is unknown. We have studied whether dlk, an epidermal growth factor-like molecule that intervenes in adipogenesis and fetal liver hematopoiesis, affects both stromal cell adipogenesis and B-cell lymphopoiesis in an established pre-B-cell culture system. Pre-B-cell cultures require both soluble interleukin-7 (IL-7) and interactions with stromal cells to promote cell growth and prevent B-cell maturation or apoptosis. We found that BALB/c 3T3 fibroblasts express dlk and function as stromal cells. Transfection of these cells with antisense dlk decreased dlk expression and increased insulin-induced adipocytic differentiation. When antisense transfectants were used as stroma, IL-7 was no longer required to support the growth of pre-B cells and prevent maturation or apoptosis. Antisense dlk transfectants of S10 stromal cells also promoted pre-B-cell growth in the absence of IL-7. These results show that modulation of dlk on stromal cells can influence their adipogenesis and the IL-7 requirements of the pre-B cells growing in contact with them. These results indicate that dlk influences differentiation signals directed both to the stromal cells and to the lymphocyte precursors, suggesting that dlk may play an important role in the bone marrow hematopoietic environment.

A role for c-myc in the regulation of thymocyte differentiation and possibly positive selection

The purpose of thymocyte differentiation is to establish the T cell repertoire and eliminate nonfunctional and autoreactive T cells. In an analysis of potential regulators of this process, we have found that c-myc expression is down-regulated dramatically during early thymocyte differentiation and subsequently up-regulated along with TCR/CD3 in CD4+8+ cells. Transgenic E beta-myc mice that constitutively express c-myc in thymocytes have a larger proportion of thymocytes with high TCR/CD3 and low heat-stable antigen-1 expression than controls, and an increase in the number of transitional cells with a CD4+CD8low phenotype. Mature E beta-myc T cells respond less vigorously than controls to activation through their TCR/CD3 complex, as measured by proliferation and induction of the activation marker CD69. These results are consistent with a hypothesis in which activation of immature T cells through TCR/CD3 induces c-myc up-regulation and drives thymocytes through the initial stage of positive selection.