Leon Lenchik

Adiponectin as a novel determinant of bone mineral density and visceral fat

Growing evidence suggests that positive associations between fat mass (FM) and bone mineral density (BMD) are mediated by not only biomechanical but also biochemical factors. Adiponectin is a novel adipocyte-derived hormone that regulates energy homeostasis and has anti-inflammatory and anti-atherogenic effects. Unlike other adipokines such as leptin, adiponectin levels decrease in obesity and type 2 diabetes. The purpose of our study was to investigate associations of serum adiponectin with BMD (DXA and QCT), FM (DXA and QCT), and serum leptin and soluble leptin receptor levels in 38 women and 42 men (age 39-81, BMI 17-55, 86% with type 2 diabetes). After adjusting for age, gender, race, smoking, and diabetes status, serum adiponectin was inversely associated with areal BMD (r = -0.20 to -0.3, all P < 0.01), volumetric BMD (r = -0.35 to -0.44, all P < 0.01), and visceral fat volume (r = -0.30, P < 0.01). These associations remained significant after adjusting for whole body fat mass. The associations of adiponectin with subcutaneous fat volume, whole body FM, and serum leptin level were not significant (all P > 0.1). These data suggest that adiponectin may play a role in the protective effects of visceral fat on BMD.

Intensive Weight Loss Program Improves Physical Function in Older Obese Adults with Knee Osteoarthritis

Objective: Physical function and body composition in older obese adults with knee osteoarthritis (OA) were examined after intensive weight loss.

Effect of exercise intensity on abdominal fat loss during calorie restriction in overweight and obese postmenopausal women: a randomized, controlled trial

BACKGROUND Exercise intensity may affect the selective loss of abdominal adipose tissue. OBJECTIVE This study showed whether aerobic exercise intensity affects the loss of abdominal fat and improvement in cardiovascular disease risk factors under conditions of equal energy deficit in women with abdominal obesity. DESIGN This was a randomized trial in 112 overweight and obese [body mass index (in kg/m(2)): 25-40; waist circumference >88 cm], postmenopausal women assigned to one of three 20-wk interventions of equal energy deficit: calorie restriction (CR only), CR plus moderate-intensity aerobic exercise (CR + moderate-intensity), or CR plus vigorous-intensity exercise (CR + vigorous-intensity). The diet was a controlled program of underfeeding during which meals were provided at individual calorie levels (approximately 400 kcal/d). Exercise (3 d/wk) involved treadmill walking at an intensity of 45-50% (moderate-intensity) or 70-75% (vigorous-intensity) of heart rate reserve. The primary outcome was abdominal visceral fat volume. RESULTS Average weight loss for the 95 women who completed the study was 12.1 kg (+/-4.5 kg) and was not significantly different across groups. Maximal oxygen uptake ( O(2)max) increased more in the CR + vigorous-intensity group than in either of the other groups (P < 0.05). The CR-only group lost relatively more lean mass than did either exercise group (P < 0.05). All groups showed similar decreases in abdominal visceral fat (approximately 25%; P < 0.001 for all). However, changes in visceral fat were inversely related to increases in O(2)max (P < 0.01). Changes in lipids, fasting glucose or insulin, and 2-h glucose and insulin areas during the oral-glucose-tolerance test were similar across treatment groups. CONCLUSION With a similar amount of total weight loss, lean mass is preserved, but there is not a preferential loss of abdominal fat when either moderate- or vigorous-intensity aerobic exercise is performed during caloric restriction. This trial was registered at (ClinicalTrials.gov) as: NCT00664729.

What is the role of serial bone mineral density measurements in patient management

The ability of dual X-ray absorptiometry (DXA) to monitor bone mineral density (BMD) has been well documented in epidemiologic and pharmaceutical trials. However, its application to monitoring of patients in clinical practice has been subject to recent controversies. Despite these controversies, most clinical centers rely on DXA for monitoring of patients, and therefore guidance is needed. In this article, we report the positions developed by an expert panel of the International Society for Clinical Densitometry on the use of densitometry for the serial measurement of bone mass for monitoring change in BMD. The panel found DXA to be a precise method of measuring change in BMD if used with an appropriate level of least significant change (LSC), at anatomic sites with good precision and response to therapy, and at 1- to 2-yr time intervals. Monitoring is acceptable for determining when therapy is indicated, and if an agent is not therapeutically effective (i.e., when bone loss occurs despite treatment). Each densitometry center should perform an in vivo precision study on individuals similar to the patient population at the center and determine LSC at a 95% confidence level. If such a precision study cannot be performed, benchmark precision might be used, although there was no agreement on what values should be used. The PA spine is the preferred anatomic site for monitoring. The total hip can be used when the spine study is technically invalid. We conclude with recommendations for further research.

Pericardial and visceral adipose tissues measured volumetrically with computed tomography are highly associated in type 2 diabetic families.

Rationale and Objectives:Pericardial and visceral adipose tissue volumes can provide new insight into the complex relation between obesity, adult-onset diabetes, and cardiovascular disease. We describe a new method for quantifying pericardial adipose tissue volumes with computed tomography (CT), and present its precision and relation to established measures of adiposity. Methods:Eighty subjects randomly selected from a family study of sibling pairs concordant for type 2 diabetes and unaffected siblings, 69 with diabetes, had 2 cardiac CT scans with electrocardiographic gating and 1 abdominal scan as part of an examination designed to measure calcified atherosclerotic plaque. Pericardial adipose tissue and visceral adipose tissue were measured using a 3-dimensional analysis technique. Body mass index, waist circumference, waist-to-hip ratio, and percent fat by dual x-ray absorptiometry were measured during the same visit. Results:Pericardial adipose tissue volumes measured independently and in a random order from the 2 sequential cardiac CT scans obtained during the same examination were highly correlated (Spearman R = 0.99; P <0.0001). The mean ± standard deviation (median) pericardial adipose tissue volume was 320.5 ± 147.3 (281.7) mL. Pericardial adipose tissue was highly correlated with total abdominal visceral adipose tissue (R = 0.81; P <0.0001). Conclusion:The significant association between pericardial and visceral adipose tissue volumes in this preliminary study suggests that pericardial, like visceral adipose tissue, may be an important predictor or risk factor for cardiovascular disease and other related illnesses and warrants further evaluation.

Effect of Voluntary Weight Loss on Bone Mineral Density in Older Overweight Women

OBJECTIVES: To examine the effect of diet and exercise‐induced weight loss on bone mineral density in overweight postmenopausal women

What Are the Criteria by Which a Densitometric Diagnosis of Osteoporosis Can Be Made in Males and Non-Caucasians?

Osteoporotic fractures are not rare in men or non-Caucasian women. However, for these groups, there is no consensus densitometric definition of osteoporosis. As is the case in Caucasian women, low bone mineral density (BMD) is associated with increased fracture risk among men and non-Caucasian women; thus, a densitometric definition of osteoporosis seems feasible. Reaching agreement on criteria for diagnosing osteoporosis in men and non-Caucasians was among the goals of the International Society for Clinical Densitometry Position Development Conference held in July 2001. To this end, the conference recommendation for males is that osteoporosis be defined as a BMD T-score of -2.5 or below the young normal mean for men. Since the relationship between BMD and fracture risk may differ between men and women, it is recommended that T scores in men continue to be derived using a male normative database. Similarly, for non-Caucasians, the recommendation is to diagnose osteoporosis at or below a T-score of -2.5. However, given the difficulty in defining race or ethnic groups, a dearth of data, and their conflicting nature correlating BMD with fracture risk in different ethnicities, it is recommended that a uniform normative database (not adjusted for race) be utilized in the United States for T-score derivation in non-Caucasians. Note that these are current clinical recommendations, which may change as additional data accumulate. Furthermore, there was agreement that the following individuals should have their bone density measured: anyone (male or female, regardless of race) with prior fragility fractures or with conditions widely recognized to increase the risk of bone loss and fracture (such as hypogonadism, corticosteroid treatment, hyperparathyroidism, alcohol abuse, anticonvulsant use, and prior gastrectomy); women on long-term hormone replacement therapy; and in the absence of these conditions, women age 65 and older (regardless of race) and men age 70 and older.

Lean Mass Loss Is Associated with Low Protein Intake during Dietary-Induced Weight Loss in Postmenopausal Women

The health and quality-of-life implications of overweight and obesity span all ages in the United States. We investigated the association between dietary protein intake and loss of lean mass during weight loss in postmenopausal women through a retrospective analysis of a 20-week randomized, controlled diet and exercise intervention in women aged 50 to 70 years. Weight loss was achieved by differing levels of caloric restriction and exercise. The diet-only group reduced caloric intake by 2,800 kcal/week, and the exercise groups reduced caloric intake by 2,400 kcal/week and expended approximately 400 kcal/week through aerobic exercise. Total and appendicular lean mass was measured using dual energy x-ray absorptiometry. Linear regression analysis was used to examine the association between changes in lean mass and appendicular lean mass and dietary protein intake. Average weight loss was 10.8+/-4.0 kg, with an average of 32% of total weight lost as lean mass. Protein intake averaged 0.62 g/kg body weight/day (range=0.47 to 0.8 g/kg body weight/day). Participants who consumed higher amounts of dietary protein lost less lean mass and appendicular lean mass (r=0.3, P=0.01 and r=0.41, P<0.001, respectively). These associations remained significant after adjusting for intervention group and body size. Therefore, inadequate protein intake during caloric restriction may be associated with adverse body-composition changes in postmenopausal women.

Measurement of trabecular bone mineral density in the thoracic spine using cardiac gated quantitative computed tomography.

Objectives: To develop a method and evaluate the performance of thoracic bone mineral density (BMD) measurement using cardiac gated quantitative computed tomography (QCT). Methods: A total of 762 participants (57% female) with a mean age of 61 years had a CT examination of the heart using prospective cardiac gating. A subset of 443 participants had replicate CT examinations of the heart. Another, nonindependent subset of 464 participants had CT examination of the abdomen. A QCT calibration phantom was included in all scans. Trabecular BMD was measured in the thoracic (T6-T11) and lumbar (T11-L4) spine. Tests of calibration and refinement and simple correlations between replicate thoracic BMD measurements and between thoracic and lumbar BMD measurements were calculated. Results: There was high correlation between replicated thoracic BMD measurements in men (r = 0.995, P < 0.0001) and in women (r = 0.995, P < 0.0001). There was high correlation between thoracic and lumbar BMD in men (r = 0.90, P < 0.0001) and in women (r = 0.94, P < 0.0001). The mean BMD was higher in the thoracic spine than the lumbar spine in men (137.58 mg/cm3 vs. 126.94 mg/cm3, P < 0.0001) and in women (152.07 mg/cm3 vs. 133.44 mg/cm3, P < 0.0001). In both genders, thoracic and lumbar BMD was inversely associated with age (all P < 0.05). Conclusions: Cardiac gated CT, primarily intended for measurement of coronary vascular calcium, can be used to measure thoracic BMD with high precision. Thoracic BMD measurements using this method are highly correlated with QCT measurements in the lumbar spine.

Executive Summary International Society for Clinical Densitometry Position Development Conference Denver, Colorado July 20–22, 2001

Bone densitometry is routinely used to assess the skeleton in patients who have diseases or conditions that can cause low bone mass. However, there are some areas of controversy related to the interpretation of bone densitometry results. To address these issues, the International Society for Clinical Densitometry (ISCD) convened a Position Development Conference in Denver, Colorado, July 20-22, 2001. The ISCD is a not-for-profit multidisciplinary society whose main mission is to promote quality in the performance and interpretation of bone densitometry examinations.