Type 2 diabetes exaggerates exercise effort and impairs exercise performance in older women

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is associated with high levels of disability and mortality. Regular exercise prevents premature disability and mortality, but people with T2DM are generally sedentary for reasons that are not fully established. We previously observed that premenopausal women with T2DM report greater effort during exercise than their counterparts without diabetes, as measured by the Rating of Perceived Exertion (RPE) scale. We hypothesized that RPE is greater in older women with T2DM versus no T2DM.

RESEARCH DESIGN AND METHODS

We enrolled overweight, sedentary women aged 50-75 years with (n=26) or without T2DM (n=28). Participants performed submaximal cycle ergometer exercise at 30 W and 35% of individually-measured peak oxygen consumption (35% VO2peak). We assessed exercise effort by RPE (self-report) and plasma lactate concentration.

RESULTS

VO2peak was lower in T2DM versus controls (p=0.003). RPE was not significantly greater in T2DM versus controls (30 W: Control, 10.4±3.2, T2DM, 11.7±2.3, p=0.08; 35% VO2peak: Control, 11.1±0.5, T2DM, 12.1±0.5, p=0.21). However, lactate was greater in T2DM versus controls (p=0.004 at 30 W; p<0.05 at 35% VO2peak). Greater RPE was associated with higher lactate, higher heart rate, and a hypertension diagnosis (p<0.05 at 30 W and 35% VO2peak).

CONCLUSIONS

Taken together, physiological measures of exercise effort were greater in older women with T2DM than controls. Exercise effort is a modifiable and thereby targetable end point. In order to facilitate regular exercise, methods to reduce exercise effort in T2DM should be sought.

TRIAL NUMBER

NCT00785005.

Timing of Ibuprofen Use and Musculoskeletal Adaptations to Exercise Training in Older Adults

Prostaglandins (PGs) 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 more robust in men than in 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.

•

The purpose was to determine whether musculoskeletal adaptations to exercise training in older adults are influenced by NSAID use.

•

Ibuprofen use did not significantly alter changes in BMD or fat-free mass, but the study may have been inadequately powered.

•

Study attrition was significantly lower in the group that took NSAIDs before exercise suggesting improved tolerance of vigorous bone-loading exercise.

•

This was the first randomized, double-blinded placebo- controlled study of ibuprofen effects on BMD from exercise in an older population.

Loss of bone strength in response to exercise-induced weight loss in obese postmenopausal women: results from a pilot study

OBJECTIVE

Exercise-induced weight loss (WL) can lead to decreased areal bone mineral density (aBMD). It is unknown whether this translates into decreased volumetric BMD (vBMD) or bone strength. The purpose of this pilot study was to determine whether exercise-induced WL results in decreased vBMD and bone strength in postmenopausal women.

METHODS

Fourteen subjects participated in a 4-month endurance exercise WL intervention. A weight stable (WS) control group (n=10) was followed for 4 months. Proximal femur aBMD was measured by DXA. Femoral neck vBMD and estimates of bone strength (cross-sectional moment of inertia (CSMI) and section modulus (SM)) were measured by quantitative CT.

RESULTS

Women were 54.6±2.4 years, BMI 32.1±5.9 kg/m(2) and 54.4±2.9 years, BMI 27.9±3.6 kg/m(2) in the WL and WS groups, respectively. The WL group lost 3.0±2.6 kg which was predominately fat mass. There was a significant decrease in SMmax. Changes in CSMImax and total hip aBMD were not significant. Total hip vBMD did not decrease significantly in response to WL. There were no significant changes in the WS group.

CONCLUSIONS

WL may lead to decreased bone strength before changes in BMD are detected. Further studies are needed to determine whether bone-targeted exercise can preserve bone strength during WL.

Estrogen or raloxifene during postmenopausal weight loss: adiposity and cardiometabolic outcomes

OBJECTIVE

Estrogen-based hormone therapy (HT) attenuates abdominal fat gain after menopause, but whether HT improves abdominal fat loss during weight loss is unknown. It was hypothesized that HT or a selective estrogen receptor modulator (raloxifene) would augment reductions in abdominal visceral fat during weight loss when compared to placebo, potentially increasing improvements in glucose tolerance and lipid profile.

METHODS

Healthy postmenopausal women (n = 119; age 50-70 yr) underwent a 6-month weight-loss (primarily exercise) intervention with randomization to raloxifene (60 mg/d), HT (conjugated estrogens, 0.625 mg/d), or placebo. Outcomes were change in total and abdominal (visceral and subcutaneous) fat mass, lipid profile, and fasting and post-challenge glucose and insulin.

RESULTS

Neither HT nor raloxifene augmented loss of total or abdominal fat mass during exercise-induced weight loss when compared with placebo. Weight loss-induced improvements in risk factors were similar among the three groups, except for a greater reduction in fasted glucose in the HT group (difference in change [95%CI] from placebo; -0.40 [-0.76, -0.05]) and greater reductions in LDL (-0.36 [-0.63, -0.09]) and increases in HDL (0.15 [0.07, 0.24]) in both treatment groups.

CONCLUSIONS

Postmenopausal HT and raloxifene did not increase abdominal fat loss during weight loss, but did improve some cardiometabolic outcomes.

Muscle strength and functional recovery during the first year after THA

BACKGROUND

Patients undergoing total hip arthroplasty (THA) often are satisfied with the decrease in pain and improvement in function they achieve after surgery. Even so, strength and functional performance deficits persist after recovery, but these remain poorly characterized; knowledge about any ongoing strength or functional deficits may allow therapists to design rehabilitation programs to optimize recovery after THA.

QUESTIONS/PURPOSES

The purposes of this study were to (1) evaluate postoperative muscle strength, function, and quality of life during the first year after THA; and (2) compare strength and function in patients 1 year after THA with a cohort of healthy peers.

METHODS

Twenty-six patients undergoing THA were assessed 1, 3, 6, and 12 months postoperatively, and 19 adults with no hip pathology were tested as a control group. Isometric muscle strength (hip flexors, extensors, abductors, knee extensors, and flexors), functional performance (stair climbing, five times sit-to-stand, timed-up-and-go, 6-minute walk, and single-limb stance tests), and self-reported function (Hip Disability and Osteoarthritis Score, SF-36, and UCLA activity score) were compared.

RESULTS

One month after THA, patients had 15% less hip flexor and extensor torque, 26% less abductor torque, 14% less knee extensor and flexor torque, and worse performance on the stair climbing, timed-up-and-go, single-limb stance, and 6-minute walk. Compared with healthy adults, patients 12 months after THA had 17% less knee extensor and 23% less knee flexor torque; however, the functional testing (including stair climbing, five times sit-to-stand, and the 6-minute walk) showed no significant differences with the patient numbers available between individuals undergoing THA and healthy control subjects. SF-36 Physical Component Scores, although significantly improved from preoperative levels, were significantly worse than healthy adults 1 year after THA (p < 0.01).

CONCLUSIONS

Patients experience early postoperative strength losses and decreased functional capacity after THA, yet strength deficits may persist after recovery. This may suggest that rehabilitation may be most effective in the first month after surgery.

Association of serum dehydroepiandrosterone sulfate and cognition in older adults: sex steroid, inflammatory, and metabolic mechanisms

OBJECTIVE

Dehydroepiandrosterone sulfate (DHEAS) levels and cognitive function decline with age, and a role for DHEAS in supporting cognition has been proposed. Higher DHEAS levels may be associated with better cognitive performance, although potential mechanisms for this relationship are not well established.

METHOD

We performed a cross-sectional study of the relationship between serum DHEAS and three aspects of cognition--executive function, working memory, and processing speed--in 49 men and 54 women, aged 60-88 years, with low serum DHEAS levels. We examined three potential mechanisms of DHEAS action--sex hormone sufficiency, inflammatory status, and glucose regulation.

RESULTS

After adjustment for multiple covariates, higher serum DHEAS levels were associated with better working memory (standardized beta coefficient 0.50, p < .05), with a trend toward better executive function (standardized beta coefficient 0.37, p < .10) in men only. There was a nonsignificant trend toward a negative association between levels of tumor necrosis factor α (TNFα) and working memory in the combined population (standardized beta coefficient -0.22, p < .10). None of the glucoregulatory measures was associated with cognitive function.

CONCLUSIONS

The relationship between DHEAS and cognition is complex and differs by sex and cognitive domain. This study supports the need for further investigations of the sex-specific effects of DHEAS on cognition and its underlying mechanisms of action.

Effects of testosterone and progressive resistance exercise in healthy, highly functioning older men with low-normal testosterone levels

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.

Cognitive decline and cardiometabolic risk among Hispanic and non-Hispanic white adults in the San Luis Valley Health and Aging Study

Cardiometabolic risk factors, including hypertension, dyslipidemia, central obesity, insulin resistance and diabetes are linked to cognitive impairment. The Hispanic population appears to be differentially affected by both cardiometabolic risk factors and cognitive impairment. We sought to determine whether ethnic differences in cognitive impairment in long-resident southwestern US elders was explained by the presence of cardiometabolic risk factors, and to explore patterns of cognitive decline over time. We performed a secondary analysis of data collected on 378 Hispanic and 409 non-Hispanic white adult participants in a longitudinal study of community-dwelling elderly in southern Colorado. Measures of cardiometabolic risk included waist circumference, blood pressure, diagnosis of diabetes, and random blood glucose. Cognitive measures included the Mini-Mental State Exam (MMSE) and the behavioral dyscontrol scale (a measure of executive cognitive function), at baseline and after an average of 22 months. Subjects were also administered the Center for Epidemiologic Studies Depression Scale, and the Coronary Artery Risk Development in Young Adults 1-Year Activity Recall. At baseline, Hispanic elders had a greater number of cardiometabolic risk factors and lower MMSE and behavioral dyscontrol scale scores than non-Hispanic whites. Hispanic ethnicity was associated with a greater likelihood of decline in general cognitive function, but not executive cognitive function, after adjusting for age and education. This differential decline was not explained by either individual or total number of baseline cardiometabolic risk factors, depression, or physical activity. A borderline increased risk of decline in general cognitive function was seen in sedentary individuals (P = 0.05).

Predicting poor physical performance after total knee arthroplasty

The purpose of this study was to develop a preliminary decision algorithm predicting functional performance outcomes to aid in the decision of when to undergo total knee arthroplasty (TKA). One hundred and nineteen patients undergoing primary unilateral TKA were evaluated before and 6 months after TKA. A regression tree analysis using a recursive partitioning function was performed with the Timed Up and Go (TUG) time, Six-Minute Walk (6MW) distance, and Stair Climbing Test (SCT) time as measured 6 months after TKA as the primary outcomes. Preoperative measures of functional performance, joint performance, anthropometrics, demographics, and self-reported status were evaluated as predictors of the primary outcomes 6 months after surgery. Individuals taking ≥10.1 s on the TUG and aged 72 years or older before surgery had the poorest performance on the TUG 6 months after surgery. Individuals walking <314 meters on the 6MW before surgery had the poorest performance on the 6MW test 6 months after surgery. Individuals taking ≥17 s to complete the SCT and scoring <40 on the SF-36 mental component score before surgery had the poorest performance on the SCT 6 months after surgery. Poorer performance preoperatively on the 6MW, SCT, and TUG, was related to poorer performance in the same measure after TKA. Age and decreased mental health were secondary predictors of poorer performance at 6 months on the TUG and SCT, respectively. These measures may help further develop models predicting thresholds for poor outcomes after TKA.

Metabolite profiling of a diverse collection of wheat lines using ultraperformance liquid chromatography coupled with time-of-flight mass spectrometry

Genetic differences among major types of wheat are well characterized; however, little is known about how these distinctions affect the small molecule profile of the wheat seed. Ethanol/water (65% v/v) extracts of seed from 45 wheat lines representing 3 genetically distinct classes, tetraploid durum (Triticum turgidum subspecies durum) (DW) and hexaploid hard and soft bread wheat (T. aestivum subspecies aestivum) (BW) were subjected to ultraperformance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOF-MS). Discriminant analyses distinguished DW from BW with 100% accuracy due to differences in expression of nonpolar and polar ions, with differences attributed to sterol lipids/fatty acids and phospholipids/glycerolipids, respectively. Hard versus soft BW was distinguished with 100% accuracy by polar ions, with differences attributed to heterocyclic amines and polyketides versus phospholipid ions, respectively. This work provides a foundation for identification of metabolite profiles associated with desirable agronomic and human health traits and for assessing how environmental factors impact these characteristics.

Effect of small for gestational age on hemodynamic parameters in the neonatal period

OBJECTIVE

The time course over which hypertension develops in children with a history of growth restriction has not been fully elucidated. The purpose of this study was to determine whether commonly obtained hemodynamic parameters were different between small for gestational age (SGA) and appropriate for gestational age (AGA) neonates.

METHODS

This was a retrospective case-control study matching 24 SGA neonates in a 1:2 fashion with 48 AGA neonates delivered during the same gestational week. Hemodynamic parameters were evaluated during the first week of life and the week prior to discharge.

RESULTS

There were no differences in blood pressure (BP) parameters during the first week of life. Compared to AGA controls, SGA neonates had a significantly lower heart rate (HR) at birth (148.2 ± 19.2 vs. 159.2 ± 17.1, p < 0.001), and a greater need for vasopressor support (OR 5.66; 95% CI 2.28, 14.04). The SGA neonates had a lower systolic BP during the week prior to discharge (68.3 ± 1.2 vs. 73.5 ± 1.2 mmHg, p < 0.001).

CONCLUSIONS

SGA newborns had a lower HR at birth and greater need for vasopressor support during the first week of life despite similar BP parameters. SGA newborns had a lower systolic BP prior to discharge. Further studies are needed to understand the progression to adult hypertension.

Effect of dietary patterns differing in carbohydrate and fat content on blood lipid and glucose profiles based on weight-loss success of breast-cancer survivors

INTRODUCTION

Healthy body weight is an important factor for prevention of breast cancer recurrence. Yet, weight loss and weight gain are not currently included in clinical-practice guidelines for posttreatment of breast cancer. The work reported addresses one of the questions that must be considered in recommending weight loss to patients: does it matter what diet plan is used, a question of particular importance because breast cancer treatment can increase risk for cardiovascular disease.

METHODS

Women who completed treatment for breast cancer were enrolled in a nonrandomized, controlled study investigating effects of weight loss achieved by using two dietary patterns at the extremes of macronutrient composition, although both diet arms were equivalent in protein: high fat, low carbohydrate versus low fat, high carbohydrate. A nonintervention group served as the control arm; women were assigned to intervention arms based on dietary preferences. During the 6-month weight-loss program, which was menu and recipe defined, participants had monthly clinical visits at which anthropometric data were collected and fasting blood was obtained for safety monitoring for plasma lipid profiles and fasting glucose. Results from 142 participants are reported.

RESULTS

Adverse effects on fasting blood lipids or glucose were not observed in either dietary arm. A decrease in fasting glucose was observed with progressive weight loss and was greater in participants who lost more weight, but the effect was not statistically significant, even though it was observed across both diet groups (P = 0.21). Beneficial effects of weight loss on cholesterol (4.7%; P = 0.001), triglycerides (21.8%; P = 0.01), and low-density lipoprotein (LDL) cholesterol (5.8%; P = 0.06) were observed in both groups. For cholesterol (P = 0.07) and LDL cholesterol (P = 0.13), greater reduction trends were seen on the low-fat diet pattern; whereas, for triglycerides (P = 0.01) and high-density lipoprotein (HDL) cholesterol (P = 0.08), a decrease or increase, respectively, was greater on the low-carbohydrate diet pattern.

CONCLUSIONS

Because an individual's dietary preferences can affect dietary adherence and weight-loss success, the lack of evidence of a negative effect of dietary pattern on biomarkers associated with cardiovascular risk is an important consideration in the development of breast cancer practice guidelines for physicians who recommend that their patients lose weight. Whether dietary pattern affects biomarkers that predict long-term survival is a primary question in this ongoing clinical trial.

Defining vitamin D status by secondary hyperparathyroidism in the U.S. population

BACKGROUND

Vitamin D is associated with a variety of health outcomes, but the exact definition of vitamin D sufficiency remains controversial.

AIM

We sought to define skeletal-related vitamin D sufficiency by estimating maximum PTH suppression in the U.S. population.

METHODS

We performed a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES), 2003-2006. We examined the association between serum 25-hydroxyvitamin D (25OHD) level and serum PTH level in 14,681 participants aged ≥6 yr. We also evaluated the 25OHD-PTH association using 2 thresholds of hyperparathyroidism: PTH≥45 pg/ml and ≥75 pg/ml.

RESULTS

The mean 25OHD level was 24 ng/ml and mean PTH was 42 pg/ml. PTH≥45 pg/ml was present in 35% of the population, while PTH≥75 pg/ml was present in 7%. The prevalence of 25OHD levels <40 ng/ml and <30 ng/ml was 95% and 77%, respectively. In both unadjusted and adjusted models, there was a strong inverse relationship between 25OHD and PTH. Compared to 25OHD≥40 ng/ml, the 25OHD-PTH association was 2.36 [95% confidence interval (CI), 2.08-2.67] times greater for 25OHD<5 ng/ml and 1.12 (95%CI, 1.07-1.17) times greater for 25OHD 30-39.9 ng/ml. Compared to 25OHD≥40 ng/ml, 25OHD levels of 20- 29.9 ng/ml [odds ratio (OR) 2.0 (95%CI, 1.4-2.8)] but not 30- 39.9 ng/ml [OR 1.1 (95%CI, 0.8-1.6)] were independently associated with PTH≥45 pg/ml.

CONCLUSIONS

Optimal vitamin D status, defined by estimated maximum PTH suppression, does not occur until at least 25OHD levels ≥40 ng/ml. Using these thresholds, most of the U.S. population needs more vitamin D. Large, prospective studies are needed to determine optimal vitamin D supplementation.

Oral dehydroepiandrosterone replacement in older adults: effects on central adiposity, glucose metabolism and blood lipids

OBJECTIVE

To determine the effects of dehydroepiandrosterone (DHEA) therapy on changes in central adiposity, insulin action and blood lipids. Many of the actions of DHEA in humans are thought to be mediated through its conversion to sex hormones, which are modulators of adiposity, muscularity and insulin sensitivity. The effects of DHEA replacement on regional tissue composition, glucose metabolism and blood lipid profile in older adults have been inconsistent.

DESIGN

A randomized, double-blinded, placebo-controlled trial. The intervention was oral DHEA 50 mg/day or placebo for 12 months.

PARTICIPANTS

Fifty-eighty women and 61 men, aged 60-88 years, with low serum DHEA sulphate (DHEAS) levels at study entry.

MEASUREMENTS

Computed tomography measures of abdominal fat areas, thigh muscle and fat areas, DXA-derived trunk fat mass, serum glucose and insulin responses to an oral glucose challenge, and fasted serum total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides were assessed before and after the intervention.

RESULTS

There were no significant (P > 0·05) differences between the DHEA and placebo groups in the changes in regional tissue composition or glucose metabolism. HDL-cholesterol (P = 0·01) and fasted triglycerides (P = 0·02) decreased in women and men taking DHEA.

CONCLUSION

Restoring serum DHEAS levels in older adults to young adult levels for 1 year does not appear to reduce central adiposity or improve insulin action. The benefit of DHEA on decreasing serum triglycerides must be weighed against the HDL-lowering effect.

Detection of circulating tumor cells in metastatic and clinically localized urothelial carcinoma

OBJECTIVE

To examine the incidence and prognostic value of circulating tumor cells (CTCs) in urothelial cancer (UC). The detection of CTCs is prognostic in several cancer types.

METHODS

A total of 44 subjects with UC were assessed for CTCs using CellSearch Technology and 7.5 mL of peripheral blood, sorted by magnetic separation (epithelial cell adhesion molecule positive) and immunofluorescent staining (positive for cytokeratin 8, 18, or 19, negative for CD45, positive for 4',6-diamidino-2-phenylindole) to identify the CTCs.

RESULTS

Five (17%) of 30 subjects with clinically localized and 7 (50%) of 14 subjects with metastatic UC had ≥1 detectable CTC (range 1-177). Six subjects had ≥5 CTCs. Fluorescence in situ hybridization analysis was performed in 20 samples from 18 unique subjects using the UroVysion probe set. Copy number gains consistent with neoplasm were observed in those with measurable CTCs but not in any of the CTC-negative samples tested. With a median follow-up of 337 days, all 7 patients with metastasis and detectable CTCs had died compared with 3 (43%) of the 7 with metastasis but without detectable CTCs.

CONCLUSION

CTCs are commonly observed in metastatic UC. CTCs were observed in 50% of the patients with metastatic UC tested. Fluorescence in situ hybridization analysis confirmed the aneusomic chromosomal content in the CTCs. These findings suggest that measurable CTCs might be prognostic for shortened survival in patients with metastatic UC, although the optimal threshold for a "positive" finding is unknown. CTCs were also detected in a subset of patients with clinically localized disease, identifying a potential high-risk, preoperative group for future study.

Acute calcium ingestion attenuates exercise-induced disruption of calcium homeostasis

PURPOSE

Exercise is associated with a decrease in bone mineral density under certain conditions. One potential mechanism is increased bone resorption due to an exercise-induced increase in parathyroid hormone (PTH), possibly triggered by dermal calcium loss. The purpose of this investigation was to determine whether calcium supplementation either before or during exercise attenuates exercise-induced increases in PTH and C-terminal telopeptide of Type I collagen (CTX; a marker of bone resorption).

METHODS

Male endurance athletes (n = 20) completed three 35-km cycling time trials under differing calcium supplementation conditions: 1) 1000 mg of calcium 20 min before exercise and placebo during, 2) placebo before and 250 mg of calcium every 15 min during exercise (1000 mg total), or 3) placebo before and during exercise. Calcium was delivered in a 1000-mg·L(-1) solution. Supplementation was double-blinded, and trials were performed in random order. PTH, CTX, bone-specific alkaline phosphatase (BAP; a marker of bone formation), and ionized calcium (iCa) were measured before and immediately after exercise.

RESULTS

CTX increased and iCa decreased similarly in response to exercise under all test conditions. When compared with placebo, calcium supplementation before exercise attenuated the increase in PTH (mean ± SE: 55.8 ± 15.0 vs 74.0 ± 14.2 pg·mL(-1), P = 0.04); there was a similar trend (58.0 ± 17.4, P = 0.07) for calcium supplementation during exercise. There were no effects of calcium on changes in CTX, BAP, and iCa.

CONCLUSIONS

Calcium supplementation before exercise attenuated the disruption of PTH. Further research is needed to determine the effects of repeated increases in PTH and CTX on bone (i.e., exercise training) and whether calcium supplementation can diminish any exercise-induced demineralization.

Effect of a low fat versus a low carbohydrate weight loss dietary intervention on biomarkers of long term survival in breast cancer patients ('CHOICE'): study protocol

Background

Weight loss in overweight or obese breast cancer patients is associated with an improved prognosis for long term survival. However, it is not clear whether the macronutrient composition of the chosen weight loss dietary plan imparts further prognostic benefit. A study protocol is presented for a dietary intervention to investigate the effects of weight loss dietary patterns that vary markedly in fat and carbohydrate contents on biomarkers of exposure to metabolic processes that may promote tumorigenesis and that are predictive of long term survival. The study will also determine how much weight must be lost for biomarkers to change in a favorable direction.

Methods/Design

Approximately 370 overweight or obese postmenopausal breast cancer survivors (body mass index: 25.0 to 34.9 kg/m²) will be accrued and assigned to one of two weight loss intervention programs or a non-intervention control group. The dietary intervention is implemented in a free living population to test the two extremes of popular weight loss dietary patterns: a high carbohydrate, low fat diet versus a low carbohydrate, high fat diet. The effects of these dietary patterns on biomarkers for glucose homeostasis, chronic inflammation, cellular oxidation, and steroid sex hormone metabolism will be measured. Participants will attend 3 screening and dietary education visits, and 7 monthly one-on-one dietary counseling and clinical data measurement visits in addition to 5 group visits in the intervention arms. Participants in the control arm will attend two clinical data measurement visits at baseline and 6 months. The primary outcome is high sensitivity C-reactive protein. Secondary outcomes include interleukin-6, tumor necrosis factor-α, insulin-like growth factor-1 (IGF), IGF binding protein-3, 8-isoprostane-F2-alpha, estrone, estradiol, progesterone, sex hormone binding globulin, adiponectin, and leptin.

Discussion

While clinical data indicate that excess weight for height is associated with poor prognosis for long term survival, little attention is paid to weight control in the clinical management of breast cancer. This study will provide information that can be used to answer important patient questions about the effects of dietary pattern and magnitude of weight loss on long term survival following breast cancer treatment.

Clinical Trial Registration

CA125243

A transfer-less, multi-well liquid culture feeding system for screening small molecules that affect the longevity of Caenorhabditis elegans

Agricultural sciences rely almost entirely on chemical assays to screen the thousands of crop cultivars generated in a crop improvement program for potential human health benefits. This situation exists in part because most animal models are expensive to implement, utilize large amounts of plant material, and require specialized facilities and technical training. A cost-effective, high-throughput animal model to screen crop extracts for small molecules with biological activity related to human health benefits would provide a much-needed resource. Here we introduce a new, relatively high-throughput method incorporating the microscopic Caenorhabditis elegans nematode, which is suitable for screening chemical extracts for bioactivity without the need for robotics. This system was chosen because longevity extension in C. elegans has been previously associated with human health benefits. Through the use of cell culture inserts, C. elegans can be exposed to fresh crop extracts daily throughout their lifespan without mechanical manipulation of the worm, thus minimizing stress and creating an environment suitable for experiments measuring longevity. Additionally, the duration of longevity experiments can be reduced by using type II right censoring in experimental design and survival analyses.

Sex differences in the association of thigh fat and metabolic risk in older adults

We have previously shown a favorable association of subcutaneous leg fat with markers of insulin resistance and dyslipidemia in postmenopausal women. It is not known whether there is a sex dimorphism in the association of lower-body adiposity with reduced metabolic risk. Thus, our primary aim was to determine whether the favorable association of thigh subcutaneous fat, independent of abdominal fat, is also observed in older men. Mid-thigh and abdominal fat areas were measured by computed tomography (CT) in 108 older men and postmenopausal women (mean ± s.d.; 69 ± 7 years). Additionally, trunk and leg fat mass (FM) were measured by dual-energy X-ray absorptiometry (DXA). Markers of insulin resistance and dyslipidemia were determined from oral glucose tolerance tests and lipid and lipoprotein measurements, respectively. Outcomes were fasted and postchallenge (area under the curve, AUC) insulin (INS(AUC)) and glucose (GLU(AUC)), product of the insulin and glucose AUC (INS(AUC) × GLU(AUC)), triglycerides (TG), and high-density lipoprotein (HDL)-cholesterol. Consistent with our previous findings in postmenopausal women, adjusting for DXA trunk FM revealed a favorable association of DXA leg FM with the metabolic risk outcomes in both older men and postmenopausal women. Likewise, adjusting for CT abdominal visceral fat generally revealed a favorable association of CT thigh fat with metabolic risk outcomes in women, but not men. The discordance between the DXA and CT results in men is unclear but may be due to sex differences in visceral fat accrual. The mechanisms underlying the protective effect of thigh fat on metabolic risk factors need to be elucidated.

Comparing pre-gap and gap behaviors for Medicare beneficiaries in a Medicare managed care plan

OBJECTIVE

To examine the impact of the coverage gap on pharmacy use, expenditures, and out-of-pocket costs for Medicare managed care beneficiaries before and after reaching the gap.

STUDY DESIGN

A longitudinal comparison of behaviors for beneficiaries with non-gap coverage before and after reaching the gap.

METHODS

Prescription drug use and expenditures were assessed for Medicare beneficiaries who reached the gap, including subsets with one of four chronic disorders (congestive heart failure (CHF), diabetes, dyslipidemia, or hypertension). Differences in pre- and post-prescription use were calculated using generalized estimating equations. Time until the end and start of the gap was estimated using a Cox proportional hazards model. Expenditure data were estimated using bootstrap methods.

RESULTS

Roughly a quarter (27.1 percent) of patients reached the gap in 2006, of whom 3.6 percent passed through the gap. The most prevalent disease state was hypertension (58.5 percent). Beneficiaries took an average of 8.1 months to reach the gap. Patients <65 years (HR = 1.42, 95% CI = 1.29 - 1.56) and those with diabetes (HR = 1.19, 95% CI = 1.12 - 1.27) were more likely to reach the gap sooner as compared to older beneficiaries (aged 65 to 74) and those without diabetes. These individuals were more likely to pass through the gap as well. Beneficiaries faced a 60.7 percent increase in out-of-pocket expenditures in the gap phase. Brand-name medication use decreased by 9.3 percent, while generic medication use increased by 7.4 percent. For chronic conditions, however, over 90 percent of individuals continued brand-name medication use in the gap.

CONCLUSIONS

Our findings suggest that, in general, beneficiaries take lower-cost generics while in the gap. However, taking brand-name medications is the predominant behavior for beneficiaries with chronic diseases. Health care reform provisions that close the gap over the next ten years may facilitate continuity of medication use while in the gap.

Fatty acids increase glucose uptake and metabolism in C2C12 myoblasts stably transfected with human lipoprotein lipase

Cellular effects of FFA might differ from those of lipoprotein triglyceride (TG)-derived fatty acids (TGFA). The aim of the current study was to examine the relationship between lipoprotein lipase (LPL) expression, TGFA, or FFA availability and glucose metabolism in the absence of insulin in C2C12 myoblasts. Control myoblasts or myoblasts stably transfected with human lipoprotein lipase (C2/LPL; 15-fold greater LPL activity) were incubated for 12 h in fetal bovine serum-free medium in the absence or presence of Intralipid-20. Intracellular retention of labeled medium glucose was assessed in a subset of experiments. In the presence of Intralipid, medium glucose disappearance was increased in C2/LPL cells but not in control cells. In both cell types, glucose label retention in cellular TG was increased in the presence of Intralipid; incubation with albumin-bound oleate produced similar results. In the presence of Intralipid, the LPL hydrolytic inhibitor tetrahydrolipstatin blocked excess glucose retention in cellular TG but did not significantly decrease glucose disappearance in C2/LPL cells. Changes in glucose transport or hexokinase II did not explain the altered glucose disappearance in C2/LPL cells. Our results suggest that LPL overexpression in these cells leads to chronic metabolic adaptations that alter glucose uptake and retention.

Wheel running-induced changes in plasma biomarkers and carcinogenic response in the 1-methyl-1-nitrosourea-induced rat model for breast cancer

The purpose of this investigation was to identify pathways by which physical activity, implemented as running in an activity wheel, inhibits carcinogenesis. The focus of this analysis was on 20 plasma biomarkers for glucose homeostasis, inflammation, cytokine function, and endocrine activity, known to be affected by a physically active lifestyle. Plasma for analysis was obtained from previously reported carcinogenesis experiments in which the effects on mammary carcinogenesis, induced by i.p. injection of 1-methyl-1-nitrosurea, of running on a motorized activity wheel or a nonmotorized free wheel were compared with sedentary controls. Wheel running reduced cancer incidence (P = 0.0004) and the number of cancers per animal (P = 0.005). Principal components analysis was used to reduce the 20 plasma biomarkers to a concise index that was significantly different by treatment group assignment (P < 0.0001). Statistical analyses provided evidence that supported the hypothesis of a mediational role of these molecules in accounting for the protective effect of wheel running on the carcinogenic process. In addition, the plasma biomarker index derived from principal components analysis was a good discriminator of treatment group assignment (only 4.5% of animals were misclassified). These findings suggest that the plasma biomarkers evaluated have utility in assessing the breast cancer response to a physical activity intervention. Identification of such biomarkers is critical in clinical studies for which evaluating the effects of physical activity on cancer outcomes (diagnosis, recurrence, or mortality) is not possible.