Biomedical subjects

R N Baumgartner

Publications and source records attributed to R N Baumgartner.

At least 37 records · Page 2Linked to original sources

PubMed2000

Comparison of air-displacement plethysmography, hydrodensitometry, and dual X-ray absorptiometry for assessing body composition of children 10 to 18 years of age.

Body density (Db) of 54 boys and girls 10-18 years of age (13.9 +/- 2.4 years) was measured in an air-displacement plethysmograph, the BOD POD, and compared to Db determined by hydrodensitometry (HW). Both Db values were converted to percent body fat (%BF) using a two-component model conversion formula and compared to %BF determined by dual energy X-ray absorptiometry (DXA). Body density estimated from the BOD POD (1.04657 +/- 0.01825 g/cc) was significantly higher than that estimated from HW (1.04032 +/- 0.01872 g/cc). The relative body fat calculated from the BOD POD (23.12 +/- 8.39 %BF) was highly correlated but, on average, 2.9% BF lower than %BF DXA. Average %BF estimates from HW and DXA were not significantly different. Despite consistently underestimating the %BF of children, the strong relationship between DXA and the BOD POD suggests that further investigation may improve the accuracy of the BOD POD for assessing body composition in children.

Absorptiometry, Photon↗

PubMed2000

Body composition in healthy aging.

Health risks in elderly people cannot be evaluated simply in conventional terms of body fatness or fat distribution. Elderly people have less muscle and bone mass, expanded extracellular fluid volumes, and reduced body cell mass compared to younger adults. These nonfat components of body composition play critical roles, influencing cognitive and physical functional status, nutritional and endocrine status, quality of life, and comorbidity in elderly people. Different patterns of "disordered body composition" have different relationships to these outcomes and may require different, tailored approaches to treatment that combine various exercise regimens and dietary supplements with hormone replacement or appetite-stimulating drugs. Skeletal muscle atrophy, or "sarcopenia," is highly prevalent in the elderly population, increases with age, and is strongly associated with disability, independent of morbidity. Elders at greatest risk are those who are simultaneously sarcopenic and obese. The accurate identification of sarcopenic obesity requires precise methods of simultaneously measuring fat and lean components, such as dual-energy X-ray absorptiometry.

Absorptiometry, Photon↗

PubMed2000

Weight stability masks sarcopenia in elderly men and women.

Skeletal muscle loss or sarcopenia in aging has been suggested in cross-sectional studies but has not been shown in elderly subjects using appropriate measurement techniques combined with a longitudinal study design. Longitudinal skeletal muscle mass changes after age 60 yr were investigated in independently living, healthy men (n = 24) and women (n = 54; mean age 73 yr) with a mean +/- SD follow-up time of 4.7 +/- 2.3 yr. Measurements included regional skeletal muscle mass, four additional lean components (fat-free body mass, body cell mass, total body water, and bone mineral), and total body fat. Total appendicular skeletal muscle (TSM) mass decreased in men (-0.8 +/- 1.2 kg, P = 0.002), consisting of leg skeletal muscle (LSM) loss (-0.7 +/- 0.8 kg, P = 0.001) and a trend toward loss of arm skeletal muscle (ASM; -0.2 +/- 0.4 kg, P = 0.06). In women, TSM mass decreased (-0.4 +/- 1.2 kg, P = 0.006) and consisted of LSM loss (-0.3 +/- 0.8 kg, P = 0.005) and a tendency for a loss of ASM (-0.1 +/- 0.6 kg, P = 0.20). Multiple regression modeling indicates greater rates of LSM loss in men. Body weight in men at follow-up did not change significantly (-0.5 +/- 3.0 kg, P = 0.44) and fat mass increased (+1.2 +/- 2.4 kg, P = 0.03). Body weight and fat mass in women were nonsignificantly reduced (-0.8 +/- 3.9 kg, P = 0.15 and -0.8 +/- 3.5 kg, P = 0.12). These observations suggest that sarcopenia is a progressive process, particularly in elderly men, and occurs even in healthy independently living older adults who may not manifest weight loss.

Absorptiometry, Photon↗

PubMed2000

Estimation of skeletal muscle mass by bioelectrical impedance analysis.

The purpose of this study was to develop and cross-validate predictive equations for estimating skeletal muscle (SM) mass using bioelectrical impedance analysis (BIA). Whole body SM mass, determined by magnetic resonance imaging, was compared with BIA measurements in a multiethnic sample of 388 men and women, aged 18-86 yr, at two different laboratories. Within each laboratory, equations for predicting SM mass from BIA measurements were derived using the data of the Caucasian subjects. These equations were then applied to the Caucasian subjects from the other laboratory to cross-validate the BIA method. Because the equations cross-validated (i.e., were not different), the data from both laboratories were pooled to generate the final regression equation SM mass (kg) = [(Ht 2 / R x 0.401) + (gender x 3.825) + (age x -0. 071)] + 5.102 where Ht is height in centimeters; R is BIA resistance in ohms; for gender, men = 1 and women = 0; and age is in years. The r(2) and SE of estimate of the regression equation were 0.86 and 2.7 kg (9%), respectively. The Caucasian-derived equation was applicable to Hispanics and African-Americans, but it underestimated SM mass in Asians. These results suggest that the BIA equation provides valid estimates of SM mass in healthy adults varying in age and adiposity.

Adolescent↗

PubMed2000

Sarcopenia: current perspectives.

The development of sarcopenia is a complex multi-factorial process which begins in mid-life and accelerates after the age of 75 years. Although exercise, nutritional supplementation, hormone replacement and pro-inflammatory cytokine therapy may improve health status and reduce mortality, a better understanding of the complex interactions between these factors are needed. This review will focus on current information regarding the roles that physical activity, hormonal changes, energy intake, oxidative stress, and inflammatory processes play on the development and progression of sarcopenia.

Adult↗

PubMed1999

Predictors of skeletal muscle mass in elderly men and women.

BACKGROUND: Elderly men and women lose muscle mass and strength with increasing age. Decreased physical activity, hormones, malnutrition and chronic disease have been identified as factors contributing to this loss. There are few data, however, for their multivariate associations with muscle mass and strength. This study analyzes these associations in a cross-sectional sample of elderly people from the New Mexico Aging Process Study. METHODS: Data collected in 1994 for 121 male and 180 female volunteers aged 65-97 years of age enrolled in The New Mexico Aging Process Study were analyzed. Body composition was measured using dual energy X-ray absorptiometry; dietary intake from 3 day food records; usual physical activity by questionnaire; health status from annual physical examinations; and serum testosterone, estrone, sex-hormone binding globulin (SHBG), and insulin-like growth factor (IGF1) from radioimmunoassays of fasting blood samples. Statistical analyses included partial correlation and stepwise multiple regression. RESULTS: The muscle mass and strength (adjusted for knee height) decreased with increasing age in both sexes. The muscle mass was significantly associated with serum free-testosterone, physical activity, cardiovascular disease, and IGF1 in the men. In the women, the muscle mass was significantly associated with total fat mass and physical activity. Age was not associated significantly with muscle mass after controlling for these variables. Grip strength was associated with age independent of muscle mass in both sexes. Estrogen (endogenous and exogenous) was not associated with muscle mass or strength in women. CONCLUSIONS: Age-related loss of muscle mass and strength occurs in relatively healthy, well-nourished elderly men and women and has a multifactorial basis. Sex hormone status is an important factor in men but not in women. Physical activity is an important predictor of muscle mass in both sexes.

Aged↗

PubMed1999

Serum leptin in elderly people: associations with sex hormones, insulin, and adipose tissue volumes.

OBJECTIVE: There are few data for associations of serum leptin with body fat, fat distribution, sex hormones, or fasting insulin in elderly adults. We hypothesized that the sex difference in serum leptin concentrations would disappear after adjustment for subcutaneous, but not visceral body fat. Serum leptin would not be associated with sex hormone concentrations or serum fasting insulin after adjusting for body fat and fat distribution. RESEARCH METHODS AND PROCEDURES: Subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volumes were measured using magnetic resonance imaging in a cross-sectional sample of 56 nondiabetic, elderly men and women aged 64 years to 94 years. Serum leptin, sex hormones (testosterone and estrone), sex hormone-binding globulin, and fasting insulin were also measured. Nine women were taking hormone replacement, and five men were clinically hypogonadal. RESULTS: Leptin was significantly associated with both SAT and VAT in each sex. Adjustment for SAT reduced the sex difference in leptin by 56%, but adjustment for VAT increased the difference by 25%. Leptin was not associated with serum estrone or hormone replacement therapy in the women, but had a significant, negative association with testosterone in the men that was independent of SAT, but not VAT. Leptin was significantly associated with fasting insulin in both sexes independent of age, sex hormones, sex hormone-binding globulin, VAT and SAT. DISCUSSION: Sex difference in serum leptin is partly explained by different amounts of SAT. Studies including both men and women should adjust for SAT rather than total body fat that includes VAT. The sex difference in serum leptin is not due to estrogen, but may be partly explained by testosterone. Testosterone is negatively associated with leptin in men, but the association is confounded with VAT. Leptin is associated with fasting insulin in nondiabetic elderly men and women independent of body fat, fat distribution, or sex hormones.

Adipose Tissue↗

PubMed1999

Comparison of energy and nutrient sources of elderly Hispanics and non-Hispanic whites in New Mexico.

OBJECTIVE: Identification and comparison of frequently consumed foods and important food sources of energy, protein, total fat, vitamin A, vitamin C, vitamin E, vitamin B-6, folate, and calcium of elderly Hispanics and non-Hispanic whites. DESIGN: Dietary intake data were collected using a modified Health Habits and History Questionnaire (a food frequency questionnaire) for 735 subjects who participated in the New Mexico Elder Health Survey. SUBJECTS: The sample consisted of 330 Hispanics (176 men and 154 women) and 405 non-Hispanic whites (214 men and 191 women) between the ages of 65 and 96 years. Subjects were those with food frequency data among 883 participants who completed the clinical visit of the New Mexico Elder Health Survey. RESULTS: Results show the top-ranked frequently consumed foods by gender and ethnicity and top-ranked food sources of energy and 8 nutrients. Regional foods were important sources of nutrients in the diets of both Hispanics and non-Hispanic whites, however, more so for the Hispanics. Chile sauces were notable sources of vitamin A, vitamin C, and folate among both groups. Both ethnic groups demonstrated selection of low-fat and skim milk and moderation in consumption of red meat. APPLICATIONS: These data will be useful for designing nutrition education programs, for studying the relationship between diet and disease among elderly Hispanics and non-Hispanic whites, and for designing assessment instruments for the elderly and other ethnic populations.

Aged↗

PubMed1999

Age-related changes in sex hormones affect the sex difference in serum leptin independently of changes in body fat.

Serum leptin concentrations are highly correlated with body fatness, but there is considerable variability among individuals after adjusting for differences in body fatness. Theoretically, sex hormone levels may influence serum leptin, since the levels are higher in women than in men independently of body fat. Increasing old age is associated with decreases in serum sex hormone concentrations and changes in body fatness that may independently alter serum leptin concentrations. In a cross-sectional sample of 106 men and 166 women aged 62 to 98 years, serum leptin adjusted for total body fat had a significant positive association with age in men and a nonsignificant negative association with age in women. Serum testosterone had a significant negative association with serum leptin in men after adjusting for total body fat, the fasting insulin resistance index (FIRI), and sex hormone-binding globulin (SHBG). In a longitudinal sample of 22 elderly men and 52 women, serum leptin levels increased significantly over a 14-year period in men, but not in women. Increases in serum leptin were significantly associated with decreases in serum testosterone but not with changes in the body mass index (BMI) in men. In contrast, changes in leptin were associated with changes in the BMI but not with changes in serum estrone in women. These results suggest that differences among men and changes with age in serum leptin are associated with circulating levels of testosterone. Elderly men become progressively "hyperleptinemic" with age regardless of changes in body fatness, possibly due to decreasing testosterone levels.

Adipose Tissue↗

PubMed1999

Hydration of fat-free body mass: review and critique of a classic body-composition constant.

The assumed "constancy" of fat-free body mass hydration is a cornerstone in the body-composition research field. Hydration, the observed ratio of total body water to fat-free body mass, is stable at approximately 0.73 in mammals and this constancy provides a means of estimating total body fat in vivo. This review examines both in vitro and in vivo data that support the hydration constancy hypothesis and provides a critique of applied methodology. Biological topics of interest are then examined and critical areas in need of future research are identified. These are important issues because water dilution is the only method currently available for estimating body fat in all mammals, which range in body mass by a factor of 10(4).

Absorptiometry, Photon↗

PubMed1999

Subclinical hypothyroidism in a biethnic, urban community.

OBJECTIVES: To evaluate the association between hypothyroidism, and the health status of older Hispanic and non-Hispanic white (NHW) men and women. To accomplish this, we determined the prevalences of the treated and untreated conditions and examined the associations between an elevated serum thyroid stimulating hormone (TSH) and cognitive and affective (mood) functions and the prevalences of symptoms and comorbidity, specifically coronary heart disease (CHD), diabetes, hypertension, and hyperlipidemia. DESIGN AND SETTING: A cross-sectional study of equal numbers of Hispanic and NHW men and women selected randomly from the Health Care Financing Administration (Medicare) rolls and recruited for a home interview followed by a 4-hour interview/examination in a senior health clinic. PARTICIPANTS: 883 volunteers, mean age 74.1 years, participated in interviews/examinations MEASUREMENTS: Serum TSH was determined in 825 participants responding to questions about thyroid replacement therapy. Serum free thyroxine (free T4) concentrations were determined in 139 participants with elevated TSH concentrations (>4.6 microU/mL). Symptoms, cognitive tests, a screen for depression, comorbidities (e.g., CHD), and risk factors (e.g., lipid abnormalities, diabetes, and hypertension) were compared in participants with high versus normal TSH values. RESULTS: Subclinical hypothyroidism is more common in women than in men and in non-Hispanic white women compared with Hispanic women. No differences were observed between participants with TSH elevations from 4.7 to 10 microU/mL and those with normal TSH concentrations, and only a few differences were observed in those with TSH concentrations above 10. CONCLUSIONS: Subclinical hypothyroidism is a common condition in community-living older people, especially women. However, it appeared to have no effect on any of the measures of health status utilized until serum TSH concentrations exceeded 10 microU/mL, and even then the effects were rarely significant.

Age Distribution↗

PubMed1999

Alcohol consumption is negatively associated with the prevalence of coronary heart disease in the New Mexico Elder Health Survey.

OBJECTIVE: To compare the prevalence of coronary heart disease (CHD) and the effects of various risk factors, including alcohol consumption, on prevalence rates in a randomly selected sample of older Hispanic and non-Hispanic white (NHW) men and women. DESIGN AND SETTING: A cross-sectional study of equal numbers of Hispanic and NHW men and women, selected randomly from Health Care Financing Authority (Medicare) rolls, recruited for a home interview followed by a 4-hour interview/examination in a senior health clinic. PARTICIPANTS: A total of 883 volunteers, mean age 74.1, years were interviewed/examined. MEASUREMENTS: CHD was identified by interview and electrocardiogram. Risk factors were identified by interview (hypertension, diabetes, medications, smoking, alcohol consumption) and by direct measurements (glucose tolerance, serum lipids, blood pressure, anthropometry). RESULTS: The age-adjusted prevalences of CHD were not significantly different when Hispanic men and women were compared with their NHW counterparts. Age-, ethnicity-, and gender-adjusted relative risk of CHD was inversely associated with alcohol consumption (OR .46; 95% CI, .28-.73; P < .001). Hypertension, diabetes mellitus, and male gender were also significant risk factors; age, anthropometric measurements, smoking, serum lipid concentrations, and level of education were not. HDL cholesterol levels were significantly lower in nondrinkers; other lipid levels were not associated with alcohol consumption. The type of alcoholic beverage was not associated with the prevalence of CHD. CONCLUSIONS: No significant differences in CHD prevalence existed between Hispanic and NHW participants despite a higher prevalence of diabetes and central obesity in Hispanics. Alcohol consumption was strongly negatively associated with the prevalence of CHD identified in this older, biethnic population.

Aged↗

PubMed1999

Hydration of fat-free body mass: new physiological modeling approach.

Water is an essential component of living organisms, and in adult mammals the fraction of fat-free body mass (FFM) as water is remarkably stable at approximately 0.73. The stability of FFM hydration is a cornerstone of the widely used water isotope dilution method of estimating total body fat. At present, the only suggested means of studying FFM hydration is by experimental total body water (TBW) and FFM measurements. Although deviations from the classical hydration constant are recognized, it is unknown if these are explainable physiological aberrations and/or methodological errors. Moreover, many questions related to hydration stability prevail, including body mass and age effects. These unresolved questions and the importance of the TBW-fat estimation method led us to develop a cellular level FFM hydration model. This physiological model reveals that four water-related ratios combine to produce the observed TBW-to-FFM ratio. The mean and range of FFM hydration observed in adult humans can be understood with the proposed physiological model as can variation in the TBW-to-FFM ratio over the human life span. An extension of the model to the tissue-organ body composition level confirms on a theoretical basis a small but systematic decrease in hydration observed in mammals ranging in body mass by a factor of 10(5). The present study, the first to advance a physiological hydration model, provides a conceptual framework for the TBW-fat estimation method and identifies important areas that remain to be studied.

Aging↗

PubMed1999

Estrogen replacement therapy, serum lipids, and polymorphism of the apolipoprotein E gene.

BACKGROUND: Pharmacogenomics, the study of genetic loci that modulate drug responsiveness, may help to explain why estrogen replacement therapy (ERT) has differential effects on serum lipid and lipoprotein concentrations in postmenopausal women who inherit distinct alleles of the apolipoprotein E gene (APOE). METHODS: We compared total-cholesterol, triglyceride, and lipoprotein (LDL and HDL) concentrations in 66 postmenopausal women receiving ERT ([+]ERT) with 174 postmenopausal women not receiving ERT ([-]ERT), controlling for three APOE genotypes divided into three groups: E2 (epsilon2/epsilon3, n = 31), E3 (epsilon3/epsilon3, n = 160), and E4 (epsilon3/epsilon4 + epsilon4/epsilon4, n = 49). RESULTS: Mean total-cholesterol concentrations were lower in all three [+]ERT groups compared with their [-]ERT counterparts but were statistically significant only for women in group E4 (P = 0.014). The mean LDL-cholesterol concentrations were significantly lower in all three [+]ERT groups compared with their [-]ERT counterparts (P </=0.005). Although all three groups of [+]ERT women tended to have higher mean HDL-cholesterol concentrations compared with their [-]ERT counterparts, the differences were not statistically significant. [+]ERT women in groups E2 and E3 had significantly higher (P <0.05) triglyceride concentrations than their [-]ERT counterparts. In [+]ERT women, the ratios of total and LDL-cholesterol to HDL-cholesterol were significantly higher in group E3 and E4 women compared with E2 women (P <0.006). Group E4 [+]ERT women had ratios of total and LDL-cholesterol to HDL-cholesterol that were comparable to group E2 [-]ERT women. CONCLUSIONS: Triglyceride concentrations in group E2 [+]ERT women may need to be monitored more closely than those in E3 or E4 [+]ERT women. Group E4 women should probably be targeted for ERT. Results suggest that APOE genotypes have a differential effect on serum lipids and lipoproteins in [+]ERT postmenopausal women.

Aged↗

PubMed1998

Epidemiology of sarcopenia among the elderly in New Mexico.

Muscle mass decreases with age, leading to "sarcopenia," or low relative muscle mass, in elderly people. Sarcopenia is believed to be associated with metabolic, physiologic, and functional impairments and disability. Methods of estimating the prevalence of sarcopenia and its associated risks in elderly populations are lacking. Data from a population-based survey of 883 elderly Hispanic and non-Hispanic white men and women living in New Mexico (the New Mexico Elder Health Survey, 1993-1995) were analyzed to develop a method for estimating the prevalence of sarcopenia. An anthropometric equation for predicting appendicular skeletal muscle mass was developed from a random subsample (n = 199) of participants and was extended to the total sample. Sarcopenia was defined as appendicular skeletal muscle mass (kg)/height2 (m2) being less than two standard deviations below the mean of a young reference group. Prevalences increased from 13-24% in persons under 70 years of age to >50% in persons over 80 years of age, and were slightly greater in Hispanics than in non-Hispanic whites. Sarcopenia was significantly associated with self-reported physical disability in both men and women, independent of ethnicity, age, morbidity, obesity, income, and health behaviors. This study provides some of the first estimates of the extent of the public health problem posed by sarcopenia.

Adult↗

PubMed1998

Helping elderly participants keep 3-day diet records in the New Mexico Aging Process Study.

Although verbal and written instructions on how to record dietary intake are commonly used in research, little information has been published describing instructional methods or materials. In the New Mexico Aging Process Study, a longitudinal study of nutrition and aging, participants keep a 3-day diet record each year. Classroom instruction and written materials are used in the study, and they were updated for use with Food Intake Analysis System (FIAS), version 2.3. This article describes the instructional methods and materials used to prepare elderly participants to keep accurate diet records; reports the development of a novel instructional tool, the food description flowcharts; and presents participants' opinions of the quality of the instruction and the usefulness of written materials. Included in the written materials were general instructions for recording food intake, examples of completed food intake and recipe forms, hints for eating out, and instructions for easy-to-use electronic scales. The flowcharts guide participants in accurately describing food intake while matching the coding requirements of FIAS. Fifty participants completed a written survey to evaluate the instructions and written materials. More than half of the respondents found the written materials to be very useful. All found the verbal instruction to be excellent or good. Nutritionists observed that records kept by participants who attended the class were generally complete and specific. The findings indicate that participants were satisfied with the instructions and written materials.

Aged↗

PubMed1998

Serum levels of cross-linked N-telopeptides and aminoterminal propeptides of type I collagen indicate low bone mineral density in elderly women.

Levels of aminoterminal propeptide (PINP) and the cross-linked carboxyterminal (ICTP) and aminoterminal (NTx) telopeptides of type I collagen were determined in the sera of 202 healthy women, 60-90 years of age, and correlated with densitometric measurements of their lumbar spine, femoral neck, and total body regions. Total skeleton bone mineral density (BMD) was associated most strongly with serum NTx levels (r = -0.51, p < 0.0001). Serum NTx and PINP levels correlated with BMD at all regions measured and were significantly increased in osteopenic women (16.0 vs. 13.3 nmol bone collagen equivalents/L for NTx, p = 0.0006 and 46.5 vs. 40.9 micrograms/L for PINP, p = 0.02). Elevations of NTx and PINP over a 3 year interval correlated with decreases in BMD measured at the femoral neck and to increases in serum concentration of alkaline phosphatase activity and ICTP. Serum levels of ICTP, NTx, PINP, ICTP, estrone, and alkaline phosphatase activity were correlated and serum NTx values were related to circulating thyroxine and intact parathyroid hormone levels. NTx and PINP levels were significantly decreased in the sera of women receiving estrogen replacement therapy (12.0 vs. 14.8 nmol bone collagen equivalents/L for NTx, and 35.5 vs. 45.2 micrograms/L for PINP, p < 0.001). Multiple regression analysis indicated that 42% of the variability observed in total skeletal BMD could be explained by age, weight, and serum levels of NTx and estrone. Within this model of covariance, the serum NTx level alone accounted for 10.1% of total body BMD variability.

Absorptiometry, Photon↗

PubMed1998

Does adipose tissue influence bioelectric impedance in obese men and women?

Bioelectric-impedance analysis overestimates fat-free mass in obese people. No clear hypotheses have been presented or tested that explain this effect. This study tested the hypothesis that adipose tissue affects measurements of resistance by using data for whole body and body segment resistance and by using muscle, adipose tissue, and bone volumes from magnetic resonance imaging for 86 overweight and obese men and women (body mass index > 27 kg/m2; age 38.5 +/- 10.2 yr). In multiple-regression analysis, muscle volumes had strong associations with resistance, confirming that the electric currents are conducted primarily in the lean soft tissues. Subcutaneous adipose tissue had a slight but statistically significant effect in women, primarily for the leg, suggesting that adipose tissue can affect measured resistance when the volume of adipose tissue is greater than muscle volume, as may occur in obese women in particular. This resulted in a slight overestimation of fat-free mass (e.g., +3 kg) when a bioelectric-impedance-analysis equation calibrated for nonobese female subjects was applied.

Adipose Tissue↗