Robert S Schwartz

University of Colorado, Denver, Colorado, United States

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Publications (313)2321.49 Total impact

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    ABSTRACT: Suppressing sex hormones in women for 1 week reduces resting energy expenditure (REE). The effects of more chronic suppression on REE and other components of total energy expenditure (TEE), and whether this is specifically due to loss of estradiol (E2), are not known. We compared the effects of 5 months of sex hormone suppression (gonadotropin releasing hormone agonist therapy, GnRHAG) with placebo (GnRHAG+PL) or (GnRHAG+E2) add-back therapy on REE and the components of TEE. Premenopausal women received GnRHAG (leuprolide acetate 3.75 mg/mo) and were randomized to receive transdermal therapy that was either (E2) (0.075 mg/d; n=24; mean±SD, aged=37±8 yr, BMI=27.3±6.2 kg/m(2)) or placebo (n=21; aged=34±9 yr, BMI=26.8±6.2 kg/m2). REE was measured using a metabolic cart, and TEE, sleep EE (SEE), exercise EE (ExEE, 2 x 30 min bench stepping), non-Ex EE (NExEE), and the thermic effect of feeding (TEF) were measured using whole-room indirect calorimetry. REE decreased in GnRHAG+PL [mean (95% CI), -54 (-98, -15) kcal/d], but not GnRHAG+E2 [+6 (-33, +45) kcal/d)] (difference in between-group changes, P<0.05). TEE decreased in GnRHAG+PL [-128 (-214, -41) kcal/d] and GnRHAGAG+E2[-96 (-159, -32) kcal/d], with no significant difference in between-group changes (P=0.55). SEE decreased similarly in both GnRHAG+PL [-0.07 (-0.12, -0.03) kcal/min)] and GnRHAG+E2 [-0.07 (-0.12, -0.02) kcal/min)]. ExEE decreased in GnRHAG+PL [-0.46 (-0.79, -0.13) kcal/min)], but not GnRHAG+E2 [-0.30 (-0.65, +0.06) kcal/min]. There were no changes in TEF or NExEE in either group. In summary, chronic pharmacologic suppression of sex hormones reduced REE and this was prevented by E2 therapy. Copyright © 2015, Journal of Applied Physiology.
    No preview · Article · Sep 2015 · Journal of Applied Physiology
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    ABSTRACT: To examine the effects of pioglitazone or endurance exercise training on cognitive function in older adults with mild cognitive impairment (MCI) and insulin resistance. Seventy-eight adults (mean age ± SD: 65 ± 7 years) with central obesity and MCI were randomized to 6 months of endurance exercise, pioglitazone or control. Sixty-six participants completed the study. Exercise training did not significantly increase peak oxygen uptake compared to control (p = 0.12). Compared to control, insulin resistance improved in the pioglitazone group (p = 0.002) but not in the exercise group (p = 0.25). There was no measureable effect of pioglitazone or exercise on cognitive performance compared to control. In this pilot study, pioglitazone improved insulin resistance but not cognitive performance in older adults with MCI and insulin resistance.
    Full-text · Article · May 2015
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    ABSTRACT: Objective: Severe, late functional tricuspid regurgitation is characterized by annulus dilation, right ventricular enlargement, and papillary muscle displacement with leaflet tethering. However, the early stages of mild tricuspid regurgitation and its progression are poorly understood. This study examined structural heart changes in mild, early tricuspid regurgitation. Methods: Sequential patients undergoing cardiac computed tomography and transthoracic echocardiography with tricuspid regurgitation were identified and evaluated. The tricuspid annulus area and chamber volumes were measured by computed tomography angiography and categorized by tricuspid regurgitation severity. Results: Patients (n = 622) were divided into 3 groups by tricuspid regurgitation severity: no/trace (n = 386), mild (n = 178), and moderate/severe tricuspid regurgitation (n = 58). Annulus area was highly dependent on and proportional to regurgitation severity and correlated with both right/left atrial enlargement. Annulus area most strongly correlated with right and left atrial volume, and the annulus shape changed from elliptical to circular in moderate/severe tricuspid regurgitation. Mild tricuspid regurgitation was associated with less right/left atrial enlargement than significant tricuspid regurgitation, normal right ventricular size, and annular dilation. Significant tricuspid regurgitation was associated with annular dilation, circularization, and right ventricular enlargement. Mild and significant tricuspid regurgitation were differentiated by annulus area and indexed right ventricular volume. Conclusions: Tricuspid annular dilation and right/left atrial enlargement comprise early events in mild functional tricuspid regurgitation. Atrial enlargement occurs before right ventricular dilation, which occurs late, when tricuspid regurgitation is severe. Atrial volume and tricuspid annular dilation are early and sensitive indicators of tricuspid regurgitation significance.
    No preview · Article · May 2015 · Journal of Thoracic and Cardiovascular Surgery
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    ABSTRACT: Suppression of ovarian hormones in premenopausal women on gonadotropin-releasing hormone agonist (GnRHAG) therapy can cause fat mass (FM) gain and fat-free mass (FFM) loss. Whether this is specifically caused by a decline in serum estradiol (E2) is unknown. This study aims to evaluate the effects of GnRHAG with placebo (PL) or E2 add-back therapy on FM, FFM, and bone mineral density (BMD). Our exploratory aim was to evaluate the effects of resistance exercise training on body composition during the drug intervention. Seventy healthy premenopausal women underwent 5 months of GnRHAG therapy and were randomized to receive transdermal E2 (GnRHAG + E2, n = 35) or PL (GnRHAG + PL, n = 35) add-back therapy. As part of our exploratory aim to evaluate whether exercise can minimize the effects of hormone suppression, some women within each drug arm were randomized to undergo a resistance exercise program (GnRHAG + E2 + Ex, n = 12; GnRHAG + PL + Ex, n = 12). The groups did not differ in mean (SD) age (36 [8] and 35 [9] y) or mean (SD) body mass index (both 28 [6] kg/m). FFM declined in response to GnRHAG + PL (mean, -0.6 kg; 95% CI, -1.0 to -0.3) but not in response to GnRHAG + E2 (mean, 0.3 kg; 95% CI, -0.2 to 0.8) or GnRHAG + PL + Ex (mean, 0.1 kg; 95% CI, -0.6 to 0.7). Although FM did not change in either group, visceral fat area increased in response to GnRHAG + PL but not in response to GnRHAG + E2. GnRHAG + PL induced a decrease in BMD at the lumbar spine and proximal femur that was prevented by E2. Preliminary data suggest that exercise may have favorable effects on FM, FFM, and hip BMD. Suppression of ovarian E2 results in loss of bone and FFM and expansion of abdominal adipose depots. Failure of hormone suppression to increase total FM conflicts with previous studies of the effects of GnRHAG. Further research is necessary to understand the role of estrogen in energy balance regulation and fat distribution.
    No preview · Article · Mar 2015 · Menopause (New York, N.Y.)
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    ABSTRACT: Prostaglandins (PG) increase in bone in response to mechanical loading and stimulate bone formation. Inhibition of cyclooxygenase (COX), the enzyme responsible for PG synthesis, by non-steroidal anti-inflammatory drugs (NSAIDs) impairs the bone formation response to loading in animals when administered before, but not after, loading. The aim was to determine whether the timing of ibuprofen use (400 mg before versus after exercise sessions) is a significant determinant of the adaptive response of BMD to exercise training in older adults. We hypothesized that taking ibuprofen before exercise would attenuate the improvements in total hip and lumbar spine BMD in response to 36 weeks of training when compared with placebo or with ibuprofen use after exercise. Untrained women and men (N=189) aged 60 to 75 years were randomly assigned to 1 of 3 treatment arms: placebo before and after exercise (PP); ibuprofen before and placebo after exercise (IP); and placebo before and ibuprofen after exercise (PI). The difference between groups in the change in BMD was not significant when IP was compared with either PP (hip, -0.5% (-1.4, 0.4); spine, 0.1% (-0.9, 1.2)) or PI (hip, 0.3% (-0.6, 1.2); spine, 0.5% (-0.5, 1.5)). Ibuprofen use appeared to have more adverse effects on BMD in women than men. The study demonstrated that ibuprofen use did not significantly alter the BMD adaptations to exercise in older adults, but this finding should be interpreted cautiously. It had been expected that the inhibition of bone formation by ibuprofen would be as robust in men than women, but this did not appear to be the case and may have limited the power to detect the effects of ibuprofen. Further research is needed to understand whether NSAID use counteracts, in part, the beneficial effects of exercise on bone.
    Full-text · Article · Jan 2015
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    ABSTRACT: Patients with presumed ST-elevation myocardial infarction (STEMI) have no clear culprit artery in approximately 10-15% of cases. We examined the value of cardiac magnetic resonance (CMR) for diagnosis in patients with "no culprit" STEMI. Data from a comprehensive prospective registry of STEMI patients were reviewed from March 2003 to December 2009. "No culprit" patients were followed for diagnosis and clinical outcome. CMR was performed at the discretion of the attending cardiologist. Of 2728 consecutive presumed STEMI patients, 412 (15%) had no clear culprit artery. Of these, 202 (49%) had abnormal cardiac biomarkers with a definitive diagnosis in 157 (78%). Diagnoses in this group included myocardial infarction without a culprit lesion (24%), myopericarditis (22%), and stress cardiomyopathy (21%). In 210 (51%) patients with normal biomarkers, only 84 (40%) received a definitive diagnosis. Diagnoses in this group included myopericarditis (27%), noncardiac causes (21%), and cardiomyopathy (14%). CMR was performed in 123 (30%) "no culprit" patients. Patients who had CMR were more likely to have a definitive diagnosis than those who did not (95/123 [77%] vs. 144/289 [50%]; P = 0.01). In particular, "no culprit" patients with abnormal biomarkers were more likely to have a definitive diagnosis with CMR. CMR led to a diagnosis different from the presumptive clinical diagnosis in 53% of all cases. CMR is a valuable diagnostic tool to improve diagnostic accuracy in patients with "no culprit" STEMI.
    No preview · Article · Dec 2014 · Critical Pathways in Cardiology
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    ABSTRACT: Objectives To determine outcomes following balloon aortic valvuloplasty (BAV) in aortic stenosis (AS) patients with a left ventricular ejection fraction (LVEF) <20%. Background Severe AS patients with a LVEF <20% are excluded from United States (U.S.) transcatheter aortic valve replacement (TAVR) trials and often surgical aortic valve replacement (AVR). The role for BAV to enhance LVEF is unclear. Methods Our BAV database of 270 consecutive patients extending from 2005 through 2010 was queried for a preoperative LVEF <20%. Demographics, echocardiograms, procedural technique, and outcomes were analyzed. Pre- and postoperative echocardiograms were used to determine improvement in aortic valve area (AVA) and LVEF. ResultsSixteen patients were identified with a median age of 82 years. The composite Society of Thoracic Surgeons' (STS) mortality risk was 16.4%. The median preoperative AVA and LVEF were 0.60 cm(2) and 16%, respectively, and postoperative AVA and LVEF were 0.77 cm(2) and LVEF 19%, respectively. About 15 of the 16 patients had postoperative echocardiograms available for comparison. And 7 of these 15 (47%) demonstrated improvement in LVEF to 20% (median LVEF 25%). The absence of coronary disease and improvement in AVA of 0.2 cm(2) was associated with postoperative LVEF of 20%. Procedural mortality was 0%. The 30-day, 6-month, and 1-year survival was 69%, 56%, and 29%. STS's mortality risk score 15% was associated with short-term mortality. Conclusion With appropriate technique, BAV can be reasonably safe in patients with LVEF <20%. Roughly half of these patients demonstrated improvement in LVEF to 20%. (c) 2013 Wiley Periodicals, Inc.
    No preview · Article · Nov 2014 · Catheterization and Cardiovascular Interventions
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    ABSTRACT: Background The efficacy of paclitaxel-coated balloons (PCB) for restenosis prevention has been demonstrated in humans. However, the mechanism of action for sustained drug retention and biological efficacy following single-time drug delivery is still unknown. Methods and results The pharmacokinetic profile and differences in drug concentration (vessel surface vs arterial wall) of two different paclitaxel coating formulations (3 µg/mm2) displaying opposite solubility characteristics (CC=crystalline vs AC=amorphous) were tested in vivo and compared with paclitaxel-eluting stents (PES). Also, the biological effect of both PCB formulations on vascular healing was tested in the porcine coronary injury model. One hour following balloon inflation, both formulations achieved similar arterial paclitaxel levels (CC=310 vs AC=245 ng/mg; p=NS). At 24 h, the CC maintained similar tissue concentrations, whereas the AC tissue levels declined by 99% (p<0.01). At this time point, arterial levels were 20-fold (CC) and 5-fold (AC) times higher compared to the PES group (p<0.05). At 28 days, arterial levels retained were 9.2% (CC) and 0.04% (AC, p<0.01) of the baseline levels. Paclitaxel concentration on the vessel surface was higher in the CC at 1 (CC=36.7% vs AC=13.1%, p<0.05) and 7 days (CC=38.4% vs AC=11%, p<0.05). In addition, the CC induced higher levels of neointimal inhibition, fibrin deposition and delayed healing compared with the AC group. Conclusions The presence of paclitaxel deposits on the vessel surface driving diffusion into the arterial tissue in a time-dependent fashion supports the mechanism of action of PCB. This specific pharmacokinetic behaviour influences the patterns of neointimal formation and healing.
    Full-text · Article · Jul 2014
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    Beret A Casey · Wendy M Kohrt · Robert S Schwartz · Rachael E Van Pelt
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    ABSTRACT: Objective We determined whether whole body and subcutaneous adipose tissue (SAT) insulin resistance was proportional to regional fat mass (FM). Design and Methods We studied postmenopausal women (Mean±SD; age 56±4 y, n=25) who were overweight or obese (BMI 29.9±5.1 kg/m2). Whole body and regional FM were measured by dual-energy x-ray absorptiometry (DXA) and computed tomography (CT). Women were studied during basal and insulin-stimulated (3-stage euglycemic clamp) conditions. Whole-body lipolysis was assessed by [2H5]glycerol rate of appearance and abdominal and femoral SAT lipolysis by interstitial glycerol (microdialysis). Results Whole body insulin resistance in skeletal muscle (insulin-stimulated glucose disposal) and adipose tissue (insulin-suppressed lipolysis) were independently related to trunk FM (r=−0.336 and 0.484, respectively), but not leg FM (r=−0.142 and −0.148, respectively). Local antilipolytic insulin resistance in abdominal, but not femoral, SAT was positively related to trunk FM (r=0.552) and visceral FM (r=0.511) but not related to leg FM (r=−0.289). Whole body and abdominal, but not femoral, adipose tissue insulin sensitivity were strongly related to skeletal muscle insulin sensitivity (r=−0.727 and −0.674, respectively). Conclusions The association of SAT insulin sensitivity (lipolysis) with adiposity and skeletal muscle insulin sensitivity is specific to the abdominal region.
    Full-text · Article · Jun 2014 · Obesity
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    ABSTRACT: In hypertrophic cardiomyopathy (HC), atrial fibrillation (AF) is an important determinant of clinical deterioration due to heart failure or embolic stroke. This study characterizes left atrial (LA) structural and functional parameters to establish markers predictive of AF risk, using cardiovascular magnetic resonance (CMR) imaging. We studied 427 consecutive patients with HC in sinus rhythm with CMR (age 44 ± 18 years), including 41 who developed clinically overt AF after study entry (2.6 ± 2.1 years), 49 patients with AF before CMR, 337 patients with HC but without AF, and 244 normal controls. LA chamber was assessed for absolute and indexed end-diastolic volume (LAEDV), end-systolic volume, and percent ejection fraction (LAEF). In the 41 prospectively studied patients with HC who developed AF during follow-up, LAEDV was significantly greater than in patients without AF (146 ± 48 vs 107 ± 37 ml) or in normal controls (81 ± 24 ml, p <0.001). Percent LAEF was lower in patients developing AF (36 ± 10%) than without AF (46 ± 12%) or controls (55 ± 9%, p <0.001). Multivariate analysis identified LAEF (<38%), LAEDV (≥118 ml), and age (≥40 years) as independently associated with AF occurrence. In conclusion, CMR measures of LA remodeling and dysfunction reliably identified patients with HC at risk for future development of AF. Decrease in LAEF represents a strong novel marker of susceptibility to AF in this disease.
    No preview · Article · Jan 2014 · The American journal of cardiology
  • Arturo G. Touchard · Robert S. Schwartz
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    ABSTRACT: Research on coronary artery atherosclerosis in humans is limited by our inability to carry out controlled experiments and by the long time required for lesions to develop. Fortunately, animal models of arterial pathology can give results comparable to those obtained in clinical trials, and provide important information about vascular responses to injury. These experimental models have become indispensable to our understanding of how coronary arteries interact with medical devices, and, in particular, to our understanding of the genesis of neointima formation. The models serve as the first stage in evaluating the safety and efficacy of new devices. They have a number of advantages: disease pathophysiology can be simulated; confounding variables can be closely controlled; and quantitative data can be obtained in a short period of time. The large variety of animal models used to study restenosis reflects the lack of an ideal model. Each model has its own advantages and disadvantages. This article contains a review of the principal animal models used to investigate restenosis, their main characteristics, and their advantages and disadvantages relative to clinical models, and discusses the factors that have to be taken into account in conceiving the ideal animal model or designing the perfect study.
    No preview · Article · Dec 2013 · Revista Española de Cardiología Suplementos
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    Full-text · Article · Oct 2013 · Journal of the American College of Cardiology
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    Full-text · Article · Oct 2013 · Journal of the American College of Cardiology
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    ABSTRACT: Advancing age is accompanied by changes in metabolic characteristics, such as reduced insulin sensitivity and low levels of vitamin D, which may exacerbate age-related declines in physical function. The aim of the present study was to determine the associations between insulin-glucose dynamics, vitamin D metabolites, and performance on a battery of motor tasks in healthy, non-diabetic older adults. Sixty-nine community-dwelling men and women (65-90 years) were recruited. Insulin-glucose dynamics were determined by an intravenous glucose tolerance test, and vitamin D metabolites were measured. Motor function was characterized by the time to walk 500 m, chair-rise time, lower body strength, dorsiflexor steadiness and endurance time, and muscle coactivation. Significant unadjusted correlations were found between insulin-glucose dynamics and 1,25-dihydroxyvitamin D [1,25(OH)2D] with walk time, strength, steadiness, endurance time, and muscle activation (p < 0.05). A significant amount of the variance in walking endurance was explained by the sex of the individual, 1,25(OH)2D, and fasting blood insulin (R (2) = 0.36, p < 0.001). Strength could be partially explained by age, body fatness, and fasting glucose (R (2) = 0.55, p < 0.001). Poor motor function in non-diabetic older men and women was associated with indices of insulin-glucose dynamics and the bio-active vitamin D metabolite 1,25(OH)2D. Walking endurance and strength were explained by 1,25(OH)2D and fasting blood glucose and insulin, even after adjusting for age, sex, and body fat. Motor function in a relatively small sample of non-diabetic older men and women was associated with metabolic factors that increase in prevalence with aging.
    Full-text · Article · Oct 2013 · Aging - Clinical and Experimental Research
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    ABSTRACT: A novel microfluidic chromatography device coupled with tandem mass spectrometry (LC-MS/MS) was utilized for the multiplex analysis of 5 steroids (testosterone, dihydrotestosterone, progesterone, cortisol, cortisone) in human serum. The use of microfluidics allowed for reduction of the chromatographic flow rate to 3μl/min with overall method run times comparable to standard flow LC-MS/MS methods reported in the literature, corresponding to a 150 fold decrease in solvent consumption. Furthermore, a simple sample preparation protocol was employed requiring injection of only 0.5μl of sample, corresponding to a 100-400 fold increase in on-column sensitivity as compared to published standard flow assays. The measured LOQ for both testosterone and progesterone was 0.4ng/mL, representing an improvement over reported literature values obtained by standard flow methods employing comparable sample preparation and large injection volumes. The LOQs for cortisol (1.9ng/mL), cortisone (0.3ng/mL), and dihydrotestosterone (1.4ng/mL) were all within a biologically relevant range. A comparison of clinical serum samples was performed for the analysis of testosterone using this microfluidic LC-MS/MS assay and the Beckman Access II automated antibody-based measurement system. The immunoassay results were systematically higher due to matrix interference which was easily resolved with the increased chromatographic resolution obtained in the microflow LC-MS/MS assay.
    Full-text · Article · Jul 2013 · Journal of chromatography. B, Analytical technologies in the biomedical and life sciences
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    ABSTRACT: One of the most compelling scenarios of embolic transport is for cardiogenic particles. These emboli are a major cause of death and disability, resulting in an estimated 20%–30% of ischemic brain strokes. Whether cardiogenic emboli continue distally in the descending aorta, or travel into the aortic branch arteries has critical consequences for stroke. Previous studies found that embolic particles tend to favor larger diameter arteries at bifurcations, which suggests that cardiogenic emboli should be preferentially transported to the descending aorta, even beyond expectations due to flow rate. However, extrapolating previous findings to this scenario is questionable because previous models do not represent the unique fluid dynamics and morphology of the ascending aorta. We utilized medical imaging and computational modeling to better understand the transport of cardiac emboli to the cerebral arteries. Results indicate that particle transport to aortic branch arteries, and subsequently the arteries to the head, has a strong size-destination predilection that varies markedly from volumetric blood flow distribution.
    No preview · Conference Paper · Jun 2013
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    Ian A Carr · Naohiko Nemoto · Robert S Schwartz · Shawn C Shadden
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    ABSTRACT: While it is intuitively clear that aortic anatomy and embolus size could be important determinants for cardiogenic embolic stroke risk and stroke location, few data exist confirming or characterizing this hypothesis. The objective of this study is to use medical imaging and computational modeling to better understand if aortic anatomy and embolus size influence predilections for cardiogenic embolic transport, and right versus left hemisphere propensity. Anatomically accurate models of the human aorta and branch arteries to the head were reconstructed from CT angiography of 10 patients. Blood flow was modeled by the Navier-Stokes equations using a well-validated flow solver with physiologic inflow and boundary conditions. Embolic particulate was released from the aortic root and tracked through the common carotid and vertebral arteries for a range of particle sizes. Cardiogenic emboli reaching the carotid and vertebral arteries appeared to have a strong size-destination relationship that varied markedly from expectations based on blood distribution. Observed trends were robust to modeling parameters. A patient's aortic anatomy appeared to significantly influence the probability a cardiogenic particle becomes embolic to the head. Right hemisphere propensity appeared dominant for cardiogenic emboli, which has been confirmed clinically. The predilections discovered through this modeling could represent an important mechanism underlying cardiogenic embolic stroke etiology.
    Full-text · Article · Jun 2013 · AJP Heart and Circulatory Physiology
  • Adit A Ginde · Marc Moss · Nathan I Shapiro · Robert S Schwartz
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    ABSTRACT: Purpose: The purpose of this study is to compare the impact of older age and nursing home residence on the incidence and morbidity of severe sepsis. Materials and methods: This was a retrospective analysis of 19460 emergency department visits from the 2005 to 2009 National Ambulatory Medical Care Surveys with diagnosis of infection with or without severe sepsis (acute organ dysfunction). Clinical outcomes included intensive care unit (ICU) admission, hospital length of stay (LOS), and in-hospital mortality. Results: Older adults (age≥65 years) were 5-fold more likely to have infections classified as severe sepsis than younger adults (6.5% vs 1.3%), and nursing home residents were 7-fold more likely to have a severe sepsis diagnosis compared with nonnursing home residents (14% vs 1.9%). Among visits for severe sepsis, older adults, compared with younger adults, had modestly higher rates of ICU admission (27% vs 21%), hospital LOS (median, 6 vs 5 days), and in-hospital mortality (24% vs 16%). Nursing home residents with severe sepsis, compared with nonnursing home residents, had significantly higher rates of ICU admission (40% vs 21%), hospital LOS (median, 7 vs 5 days), and in-hospital mortality (37% vs 15%). Conclusions: Older adults and particularly nursing home residents have a disproportionately high incidence of and morbidity from severe sepsis.
    No preview · Article · May 2013 · Journal of critical care
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    ABSTRACT: Background: Left atrial three-dimensional shape and contraction patterns are not well described. We quantified the LA using three-dimensional cardiac MRI (CMR) in a group of normal subjects. Methods: Three-dimensional vectors were used to quantitate atrial shape and contraction using a geometric model as a three-dimensional prolate ellipsoid. Atrial area and length at end-systole and end-diastole were made in the horizontal long axis (HLA) and vertical long axis (VLA) planes. Biplane area-length products and the orthogonal LA long axis vector comprised 3 orthogonal vector lengths composed of axis measures for shape and volume calculations at end-diastole and end-systole. Vector fractional shortening in 3 dimensions was calculated for each 3-space orthogonal vector. Echocardiograms were used for comparison. Results: The normal LA is an oblate ellipsoid with significantly longer HLA short axis than the vertical VLA short axis (p<0.001). LA contraction in the long axis dimension is smaller than both HLA and VLA short axis dimensional changes (p<0.001). Linear correlations between LAEDV vs. LASV and LAESV vs. LAEF were highly significant. Conclusions: This dimensional analysis quantitates normal left atrial shape for the first time, modeled as a prolate 3-D ellipsoid. LA contractile functions and derives mostly from contraction in the HLA and VLA short axis directions. Though LA end-diastolic volume is considered the marker of left atrial health or disease, this notion should be reconsidered in view of LA static and functional modeling in 3 dimensions.
    No preview · Article · May 2013 · International journal of cardiology
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    ABSTRACT: Context:Aging in men is associated with reduced testosterone (T) levels and physiological changes leading to frailty, but the benefits of T supplementation are inconclusive.Objective:We studied the effects of T supplementation with and without progressive resistance training (PRT) on functional performance, strength, and body composition.Design, Setting, and Participants:We recruited 167 generally healthy community-dwelling older men (66 ± 5 years) with low-normal baseline total T levels (200-350 ng/dL).Intervention:Subjects were randomized to placebo or transdermal T gel [2 doses targeting either a lower (400-550 ng/dL) or higher (600-1000 ng/dL) T range] and to either PRT or no exercise for 12 months.Main Outcome Measure:The primary outcome was functional performance, whereas secondary outcomes were strength and body composition.Results:A total of 143 men completed the study. At 12 months, total T was 528 ± 287 ng/dL in subjects receiving any T and 287 ± 65 ng/dL in the placebo group. In the PRT group, function and strength were not different between T- and placebo-treated subjects, despite greater improvements in fat mass (P = .04) and fat-free mass (P = .01) with T. In the non-PRT group, T did not improve function but improved fat mass (P = .005), fat-free mass (P = .03), and upper body strength (P = .03) compared with placebo. There were fewer cardiovascular events in the T-treated groups compared with placebo.Conclusions:T supplementation was well tolerated and improved body composition but had no effect on functional performance. T supplementation improved upper body strength only in nonexercisers compared with placebo.
    Full-text · Article · Mar 2013 · The Journal of Clinical Endocrinology and Metabolism

Publication Stats

16k Citations
2,321.49 Total Impact Points


  • 2006-2015
    • University of Colorado
      • • Division of Geriatric Medicine
      • • Department of Medicine
      Denver, Colorado, United States
    • Abbott Northwestern Hospital
      Minneapolis, Minnesota, United States
  • 2002-2014
    • Minneapolis Heart Institute
      Minneapolis, Minnesota, United States
    • Massachusetts General Hospital
      Boston, Massachusetts, United States
  • 2005-2013
    • University of Colorado at Boulder
      Boulder, Colorado, United States
    • University of Rome Tor Vergata
      Roma, Latium, Italy
  • 2010
    • Duke University
      Durham, North Carolina, United States
    • Cardiovascular Research Foundation
      New York, New York, United States
    • American College of Cardiology
      Washington, Washington, D.C., United States
  • 2008
    • McMaster University
      • Faculty of Health Sciences
      Hamilton, Ontario, Canada
  • 2007-2008
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
    • Toho University
      Edo, Tōkyō, Japan
    • East Carolina University
      North Carolina, United States
  • 1991-2005
    • University of Washington Seattle
      • • Division of Gerontology and Geriatric Medicine
      • • Department of Medicine
      Seattle, Washington, United States
  • 2003
    • Second University of Naples
      Caserta, Campania, Italy
    • Yale-New Haven Hospital
      New Haven, Connecticut, United States
  • 2001-2002
    • Aarhus University
      Aarhus, Central Jutland, Denmark
  • 1983-2002
    • Mayo Clinic - Rochester
      • Department of Cardiovascular Diseases
      Rochester, Minnesota, United States
  • 1999
    • University of Ottawa
      Ottawa, Ontario, Canada
    • Universität Witten/Herdecke
      Witten, North Rhine-Westphalia, Germany
  • 1997
    • Swedish Medical Center Seattle
      Seattle, Washington, United States
    • VA Puget Sound Health Care System
      Washington, Washington, D.C., United States
  • 1996
    • St. Elizabeth's Medical Center
      Boston, Massachusetts, United States
    • University of California, Los Angeles
      Los Ángeles, California, United States
  • 1995
    • University of Michigan
      • Department of Epidemiology
      Ann Arbor, Michigan, United States