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PubMedDate not supplied

Fat-suppressed 3D-T1-weighted-echo planar imaging: comparison with fat-suppressed 3D-T1-weighted-gradient echo in imaging the cartilage of the knee.

This study was conducted to compare a three-dimensional (3D) multi-shot echo-planar imaging (EPI) sequence with fat-suppression (FS) with the 3D-fat-suppressed gradient echo (GRE-FS) sequence in imaging the cartilage of the knee. One hundred sixty-nine patients were studied prospectively. The cartilage was imaged in the sagittal plane with: (a) 3D-T1-EPI-FS and (b) 3D-T1-GRE-FS sequences using a 1T MR scanner. The signal-to-noise ratio (SNR) of bone (b) and cartilage (c), and relative contrast (ReCon) between bone and cartilage and meniscus and cartilage were measured in 60 patients with arthroscopically normal cartilage. The imaging accuracy was assessed by comparing with linear regression analysis (length and depth) 32 defects in the cartilage of cadaveric (human and bovine) knees. The 3D-T1-EPI-FS provided better bone marrow signal suppression, better SNRc and better ReCon(bc) and ReCon(cm) (p<0.01). The 3D-T1-EPI-FS showed better accuracy concerning the depth of the defects and the 3D-T1-GRE-FS better accuracy concerning the length of the defects. In conclusion, the 3D-T1-EPI-FS pulse sequence could be included in the routine protocol in imaging the cartilage of the knee because it achieves high SNR of the cartilage and high ReCon compared to the surrounding structures, at a reduced scan time.

Adipose Tissue↗
PubMed2000

Reference values of fat-free and fat masses by bioelectrical impedance analysis in 3393 healthy subjects.

Determination of fat-free mass (FFM) and fat mass (FM) is of considerable interest in the evaluation of nutritional status. In recent years, bioelectrical impedance analysis (BIA) has emerged as a simple, reproducible method used for the evaluation of FFM and FM, but the lack of reference values reduces its utility to evaluate nutritional status. The aim of this study was to determine reference values for FFM, FM, and %FM by BIA in a white population of healthy subjects, to observe the changes in these values with age, and to develop percentile distributions for these parameters. Whole-body resistance of 1838 healthy white men and 1555 women, aged 15-64 y, was determined by using four skin electrodes on the right hand and foot. FFM and FM were calculated according to formulas validated for the subject groups and analyzed for age decades. This is the first study to present BIA-determined age- and sex-specific percentiles for FFM, FM, and %FM for healthy subjects, aged 15-64 y. Mean FM and %FM increased progressively in men and after age 45 y in women. The results suggest that any weight gain noted with age is due to a gain in FM. In conclusion, the data presented as percentiles can serve as reference to evaluate the normality of body composition of healthy and ill subject groups at a given age.

Adipose Tissue↗
PubMedDate not supplied

Fat-free and fat mass percentiles in 5225 healthy subjects aged 15 to 98 years.

OBJECTIVES: Fat-free mass (FFM) and fat mass (FM) are important in the evaluation of nutritional status. Bioelectrical impedance analysis (BIA) is a simple, reproducible method used to determine FFM and FM. Because normal values for FFM and FM have not yet been established in adults aged 15 to 98 y, its use is limited in the evaluation of nutritional status. The aims of this study were to determine reference values for FFM, FM, and percentage of FM by BIA in a white population of healthy adults, observe their differences with age, and develop percentile distributions for these parameters between ages 15 and 98 y. METHODS: Whole-body resistance and reactance of 2735 healthy white men and 2490 healthy white women, aged 15 to 98 y, was determined by 50-kHz BIA, with four skin electrodes on the right hand and foot. FFM and FM were calculated by a previously validated, single BIA formula and analyzed for age decades. RESULTS: Mean FFM peaked in 35- to 44-y-old men and 45- to 54-y-old women and declined thereafter. Mean FFM was 8.9 kg or 14.8% lower in men older than 85 y than in men 35 to 44 y old and 6.2 kg or 14.3% lower in women older than 85 y than in women 45 to 54 y old. Mean FM and percentage of FM increased progressively in men and women between ages 15 and 98 y. The results suggested that the greater weight noted in older subjects is due to larger FM. CONCLUSIONS: The percentile data presented serve as reference to evaluate deviations from normal values of FFM and FM in healthy adult men and women at a given age.

Adipose Tissue↗
PubMedDate not supplied

Relevance of hydration state of the fat free mass in estimating fat mass by body impedance analysis.

Body impedance analysis (BIA) is widely used to assess body composition, however, accurate estimates of fat mass (FM) are sometimes rendered impossible due to over- or dehydration states. In fact, BIA is accurate in total body water (TBW) estimates, and TBW can be converted into fat free mass (FFM) assuming 73% hydration; but, if there is an alteration in the hydration state, such a fixed value does not fit with the real content of fluids in the FFM compartment, thus causing wrong estimates of FFM and in turn of FM. For this reason, phase-sensitive bioelectric analyzers operating at a single frequency or at multiple frequencies have recently been under investigation in order to produce an equation that is also able to estimate the volume of extracellular water (ECW). Some authors, rather than trying to find the best equation or the best instrument approach, have tested the direct use of resistance, reactance and phase angle values derived from 50 kHz impedance measurements, assuming that normal bioelectrical values are associated with normal hydration states. Using a large series of data we have found strong correlations between BIA-derived FM and BMI, and our data show that screening the subjects with normal hydration states using the direct bioelectrical parameters (BIAGRAM) improves the predictivity of standard equations, since it avoids trying to estimate FM in overhydrated subjects.

Adipose Tissue↗
PubMed2000

Evidence of pleiotropic loci for fasting insulin, total fat mass, and abdominal visceral fat in a sedentary population: the HERITAGE family study.

OBJECTIVE: To examine whether there is a major gene effect on fasting insulin and pleiotropic loci for fasting insulin, total fat mass (FM), and abdominal visceral fat (AVF). RESEARCH METHODS AND PROCEDURES: A major gene hypothesis for fasting plasma insulin levels was assessed using segregation analyses of data on 495 members in 98 normolipidemic sedentary families of white descent who participated in the HERITAGE Family Study. RESULTS: Segregation analyses were performed on insulin adjusted for age, on insulin adjusted for age and FM, and on insulin adjusted for age and AVF. Before adjustment for AVF and FM, a major gene effect on fasting insulin levels was indicated. The putative locus accounted for 54% of the variance under a recessive inheritance pattern, affecting 11% of the sample (i.e., allele frequency = 0.33). However, after adjusting for the effects of AVF or FM, neither a major effect alone nor a multifactorial component alone could be rejected, and support for a major gene was equivocal, i.e., neither the hypothesis of Mendelian tau values or that of the equal tau(s) were rejected and the equal tau model fit the data better than the Mendelian tau model. This pattern (i.e., major gene evidence for insulin before but not after adjustment for AVF or FM) suggests that there is a putative locus with pleiotropic effects on both insulin and FM and another pleiotropic locus for both insulin and AVF. DISCUSSION: Although these data do not directly support an additional major gene for insulin independent of AVF and FM, such support cannot be ruled out because there is still a significant major effect on FM- or AVF-adjusted insulin (albeit the Mendelian nature of this effect is ambiguous).

Abdomen↗
PubMed1997

Changes in fat-free mass and fat mass in postpartum women: a comparison of body composition models.

OBJECTIVES: (1) To compare 2-, 3- and 4-component models of body composition based on total body water (TBW), underwater weighing (UWW), skinfold thicknesses (SF), total body potassium (TBK), dual-energy X-ray absorptiometry (DXA) and total body electrical conductivity (TOBEC); (2) to compare postpartum changes in body composition estimated by the 2-, 3- and 4-component models and (3) to test for an effect of pregnancy or lactation on the hydration, density and potassium content of fat free mass (FFM) in postpartum women. DESIGN: Longitudinal measurements of body composition at 3, 6 and 12 months postpartum. SUBJECTS: Thirty-five healthy postpartum women, aged 30.2 +/- 3.5 y. MEASUREMENTS: Body composition was estimated by 2-component models based on TBW, UWW, SF, TBK, DXA or TOBEC; 3-component models based on TBW and UWW (Fuller 3, Siri 3); and a 4-component model (Fuller 4) based on TBW, UWW and bone mineral content. RESULTS: Systematic differences were seen among the various body composition models, with the following ranking from lowest to highest estimate of fat mass (FM): TOBEC, TBW, Fuller 3, Siri 3, Fuller 4, UWW, SF, TBK, and DXA. Estimated changes in FFM and FM were not significantly different among methods, except for the 3-6 months FFM and FM changes estimated from TBW, which differed from SF, DXA, and TOBEC. Pregnancy-induced changes in the hydration, density and potassium content of FFM were not evident by 3 months postpartum (0.73 +/- 0.02, 1.099 +/- 0.015 kg/l and 2.31 +/- 0.10 g/kg, respectively). CONCLUSION: In spite of systematic differences among body composition models for the measurement of FFM and FM, changes in FFM and FM did not differ significantly among the models. Since there was no apparent effect of pregnancy or lactation on the postpartum composition of FFM, 2-component models of body composition are acceptable for use in postpartum women beyond the puerperium.

Adult↗
PubMed2001

Relationships between tamoxifen use, liver fat and body fat distribution in women with breast cancer.

Tamoxifen is a nonsteroidal anti-estrogenic drug used for adjuvant treatment of breast cancer and recently as a chemopreventative agent for breast cancer and, on an investigational basis, for other cancers. To date there are case reports of hypertriglyceridemia and fatty liver disease in tamoxifen users. Fatty liver is associated with visceral obesity and other components of the metabolic syndrome. Here we evaluated steatosis and adipose tissue distribution by CT scan in a cross-sectional study of 32 women on tamoxifen and 39 control women. Tamoxifen users had more visceral adipose tissue (VAT) and more liver fat than controls. This is the first study to demonstrate that fatty liver and intra-abdominal fat accumulation are common in breast cancer patients receiving tamoxifen. Prospective studies of tamoxifen should monitor metabolic changes in obese women with or without breast cancer.

Adipose Tissue↗
PubMed1979

Activities of enzymes of fat and ketone-body metabolism and effects of starvation on blood concentrations of glucose and fat fuels in teleost and elasmobranch fish.

1. Activities of 3-oxo acid CoA-transferase and carnitine palmitoyltransferase together with tri- and di-acylglycerol lipase were present in red and heart muscles of the teleost fish. However, d-3-hydroxybutyrate dehydrogenase activity was not detectable. These results suggest that the heart and red muscles of the teleosts should be able to utilize the fat fuels triacylglycerol, fatty acids or acetoacetate, but not hydroxybutyrate. The muscles from the elasmobranchs differed in that d-3-hydroxybutyrate dehydrogenase and 3-oxo acid CoA-transferase activities were present, but carnitine palmitoyltransferase activity was not detectable. This suggests that ketone bodies are the most important fat fuels in elasmobranchs. 2. The concentrations of acetoacetate, 3-hydroxybutyrate, glycerol, non-esterified fatty acids and triacylglycerols were measured in blood or plasma of several species of fish (teleosts and elasmobranchs) in the fed state. Teleosts have a 10-fold higher concentration of plasma non-esterified fatty acids, but a lower blood concentration of ketone bodies; both acetoacetate and 3-hydroxybutyrate are present in blood of elasmobranchs, whereas 3-hydroxybutyrate is absent from that of the teleosts. 3. The effects of starvation (up to 150 days) on the concentrations of blood metabolites were studied in a teleost (bass) and an elasmobranch (dogfish). In the bass there was a 60% decrease in blood glucose after 100 and 150 days starvation. In dogfish there was a large increase in the concentration of ketone bodies, whereas in bass the concentration of acetoacetate (the only ketone body present) remained low (<0.04mm) throughout the period of starvation. The concentration of plasma non-esterified fatty acids increased in bass, but decreased in dogfish. These changes are consistent with the predictions based on the enzyme-activity data. 4. Starvation did not change the activities of ketone-body-utilizing enzymes or that of phosphoenolpyruvate carboxykinase in heart and red skeletal muscles of both fish, but it decreased markedly the activity of phosphoenolpyruvate carboxykinase in white skeletal muscle of both fish. However, in the liver of the dogfish, starvation resulted in a twofold increase in the activities of 3-hydroxybutyrate dehydrogenase and acetoacetyl-CoA thiolase, whereas in bass liver it decreased the activity of acetoacetyl-CoA thiolase and increased that of 3-oxo acid CoA-transferase. The activity of phosphoenolpyruvate carboxykinase was increased twofold in the liver of bass, but was unchanged in that of the dogfish. 5. The difference in changes in concentrations of blood metabolites and enzyme activities in the two fish support the suggestion that, in starvation, ketone bodies, but not non-esterified fatty acids, are an important fuel for muscle in elasmobranchs, whereas non-esterified fatty acids, but not ketone bodies, are an important fuel in teleosts. The results are discussed in relation to the evolution of a discrete lipid-storing adipose tissue in teleosts and higher vertebrates.

Animals↗
PubMed1981

Seasonal variation in the response of adipose tissue to a serum fat-mobilizing factor may be explained in terms of reduced availability of fat cell receptors.

The lipolytic activity of serum obtained from fasted rats on rat isolated rat cells, exhibits seasonal trends. If it is assumed that the serum lipolytic agonist combines with receptors on fat cell membranes, and that the measured physiological response (glycerol release) is proportional to the number of such combinations, then the observed seasonal variation could be due to changes in serum concentration of lipolytic agonist, or the sensitivity of cells towards the same concentration of agonist (or both). On the basis of the observations described herein, it is proposed that the seasonal fluctuation in fat cell sensitivity is the result of some measure of altered availacbility of receptors for the lipolytic agonist. Possible changes in the concentration of circulating agonist, which were not investigated, may also play a role.

Adipose Tissue↗
PubMed2001

Impaired prohormone convertases in Cpe(fat)/Cpe(fat) mice.

A spontaneous point mutation in the coding region of the carboxypeptidase E (CPE) gene results in a loss of CPE activity that correlates with the development of late onset obesity (Nagert, J. K., Fricker, L. D., Varlamov, O., Nishina, P. M., Rouille, Y., Steiner, D. F., Carroll, R. J., Paigen, B. J., and Leiter, E. H. (1995) Nat. Genet. 10, 135-142). Examination of the level of neuropeptides in these mice showed a decrease in mature bioactive peptides as a result of a decrease in both carboxypeptidase and prohormone convertase activities. A defect in CPE is not expected to affect endoproteolytic processing. In this report we have addressed the mechanism of this unexpected finding by directly examining the expression of the major precursor processing endoproteases, prohormone convertases PC1 and PC2 in Cpe(fat) mice. We found that the levels of PC1 and PC2 are differentially altered in a number of brain regions and in the pituitary. Since these enzymes have been implicated in the generation of neuroendocrine peptides (dynorphin A-17, beta-endorphin, and alpha- melanocyte-stimulating hormone) involved in the control of feeding behavior and body weight, we compared the levels of these peptides in Cpe(fat) and wild type animals. We found a marked increase in the level of dynorphin A-17, a decrease in the level of alpha-melanocyte-stimulating hormone, and an alteration in the level of C-terminally processed beta-endorphin. These results suggest that the impairment in the level of these and other peptides involved in body weight regulation is mainly due to an alteration in carboxypeptidase and prohormone convertase activities and that this may lead to the development of obesity in these animals.

Amino Acid Sequence↗
PubMedDate not supplied

[The phosphorus supply of pigs in the body weight category of 11-38 kg. 1. The effect of the phosphorus supply on the performance, nutrient digestibility, protein and fat content in soft tissue and skeleton and protein and fat deposits].

The influence of phosphorus supply on performance and nutrient composition of the empty body was studied in two individual feeding experiments with two and three groups resp. (7 or 8 animals per group). The phosphorus content of the unsupplemented diet was in the experiments I and II 2.97 and 2.41 g/kg, the supplemented phosphorus (as monocalcium phosphate) amounted of 2.5 and 2.33 g/kg diet respectively. The phosphorus supplementation increased live weight gain in both experiments by 84 and 45% and improved feed conversion by 35 and 23% respectively. Phosphorus deficiency did not influence the digestibility of nutrients. The fat content of soft tissue and skeleton of the phosphorus deficient animals was increased. They deposited 0.7 kg more fat (in both experiments) and 1.5 or 0.7 kg less protein in experiment I and II respectively. The utilisation of energy for deposition was not influenced by the different phosphorus supply.

Adipose Tissue↗
PubMed1990

Height-normalized indices of the body's fat-free mass and fat mass: potentially useful indicators of nutritional status.

Expressing fat-free mass (FFM) and body fat mass (BFM) as percentages of body weight or by weight is unsatisfactory. For example, tall patients with protein-energy malnutrition (PEM) can exhibit values for FFM and BFM similar to those of shorter well-nourished individuals. To obviate such difficulties, we propose use of height-normalized indices, namely, a FFM index [FFM (kg)/height (m)2, or FFMI] and a BFM index [BFM (kg)/height (m)2, or BFMI]. We calculated these indices in a reference population of 124 healthy young men and in 32 nonobese young men (from the Minnesota Study) before, during, and after experimental semistarvation. When values for FFMI and BFMI falling below the reference cohort's 5th percentile cutoff point were used as a criterion for PEM, these indices, together with basal oxygen-consumption rate, diagnosed PEM in 27 of the 32 Minnesota Study subjects after 12 wk of semi-starvation. These findings indicate that FFMI and BFMI may be useful in nutritional assessment.

Adipose Tissue↗
PubMed1992

Prediction of resting energy expenditure from fat-free mass and fat mass.

On the basis of literature values, the relationship between fat-free mass (FFM), fat mass (FM), and resting energy expenditure [REE (kJ/24 h)] was determined for 213 adults (86 males, 127 females). The objectives were to develop a mathematical model to predict REE based on body composition and to evaluate the contribution of FFM and FM to REE. The following regression equations were derived: 1) REE = 1265 + (93.3 x FFM) (r2 = 0.727, P < 0.001); 2) REE = 1114 + (90.4 x FFM) + (13.2 x FM) (R2 = 0.743, P < 0.001); and 3) REE = (108 x FFM) + (16.9 x FM) (R2 = 0.986, P < 0.001). FM explained only a small part of the variation remaining after FFM was accounted for. The models that include both FFM and FM are useful in examination of the changes in REE that occur with a change in both the FFM and FM. To account for more of the variability in REE, FFM will have to be divided into organ mass and skeletal muscle mass in future analyses.

Adipose Tissue↗
PubMed1995

Body fat and fat-free mass in infants: new and classic anthropometric indexes and prediction equations compared with total-body electrical conductivity.

Anthropometry is frequently used for nutritional assessment. Little is known in infants about the validity of anthropometric measurements in relation to whole-body fat (TBF) and fat-free mass (FFM) composition. We compared TBF and FFM estimations by total-body electrical conductivity (TOBEC) with anthropometry in 435 healthy infants ages 21-365 d. TBF was best correlated with weight-for-length and calf circumference (r2 = 0.84, r2 = 0.83). FFM was best correlated with body weight (r2 = 0.93). Upper-arm anthropometry, skinfold thickness, and Quetelet's and Ponderal indexes were poorly correlated with TBF and FFM (r2 < 0.65). New anthropometry-based prediction equations were calculated (r2 = 0.90 for TBF and r2 = 0.95 for FFM). New simple indexes (analogous to Quetelet's index) were calculated for TBF (weight x calf circumference/length; r2 = 0.87) and for FFM (square root of weight x length; r2 = 0.95). Prediction equations and indexes were cross-validated in a second population by a second observer. Interobserver variation was largest for equations with skinfold thicknesses included. We conclude that anthropometry can be used for rough estimations of infant body composition, although indexes different than those used in children and adults are preferred.

Adipose Tissue↗
PubMed2005

Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine.

BACKGROUND: Basal metabolic rate (BMR) is the largest component of daily energy demand in Western societies. Previous studies indicated that BMR is highly variable, but the cause of this variation is disputed. All studies agree that variation in fat-free mass (FFM) plays a major role, but effects of fat mass (FM), age, sex, and the hormones leptin, triiodothyrionine (T3), and thyroxine (T4) remain uncertain. OBJECTIVE: We partitioned the variance in BMR into within- and between-subject effects and explored the roles of FFM, FM, bone mineral content, sex, age, and circulating concentrations of plasma leptin, T3, and T4. DESIGN: This was a cross-sectional study of 150 white adults from northeast Scotland, United Kingdom. RESULTS: Only 2% of the observed variability in BMR was attributable to within-subject effects, of which 0.5% was analytic error. Of the remaining variance, which reflected between-subject effects, 63% was explained by FFM, 6% by FM, and 2% by age. The effects of sex and bone mineral content were not significant (P > 0.05). Twenty-six percent of the variance remained unexplained. This variation was not associated with concentrations of circulating leptin or T3. T4 was not significant in women but explained 25% of the residual variance in men. CONCLUSIONS: Our data confirm that both FFM and FM are significant contributors to BMR. When the effect of FM on BMR is removed, any association with leptin concentrations disappears, which suggests that previous links between circulating leptin concentrations and BMR occurred only because of inadequate control for the effects of FM.

Absorptiometry, Photon↗
PubMedDate not supplied

Fat (fat) and tubby (tub): two autosomal recessive mutations causing obesity syndromes in the mouse.

This report describes the development of obesity syndromes in mice caused by two autosomal recessive mutations, fat (fat), located on chromosome 8, and tubby (tub), located on chromosome 7. Both mutations cause slowly developing but ultimately severe obesity conditions. Although hyperinsulinemia, hyperactivity of the beta cell of the islets of Langerhans, and beta-cell degranulation are consistent features, these obesity syndromes do not progress to severe diabetes. The many different single-gene mutations in the mouse that produce obesity-diabetes syndromes of varying degrees of severity make the mutant mouse a powerful tool for analyzing the number and nature of the primary defects than can cause obesity states.

Aging↗
PubMed1979

Oral fat loading test: a reliable procedure for the study of fat malabsorption in children.

Oral triglyceride (TG) loading tests were performed in four groups of children: normal controls, patients with chronic nonspecific diarrhoea (CND), biopsy-proved mucosal pathology (MP), and disturbed intraluminal fat malabsorption (IFM). The rise of plasma TG levels greater than or equal to 55 mg/100 ml (greater than or equal to 0.6 mmol/l) can discriminate between patients with gastrointestinal disease and normal controls or patients with functional disturbances. The postmeal plasma TG rise correlates well with the coefficient of fat absorption (CFA) in normal subjects, patients with CND, and patients with IFM, but not in patients with MP who showed a disproportionally low plasma TG rise compared with their CFA. This test can serve as a useful tool in diagnosis and clinical evaluation for children with gastrointestinal disorders.

Adolescent↗
PubMed1996

Standards for total body fat and fat-free mass in infants.

Data on body composition in conjunction with reference centiles are helpful in identifying the severity of growth and nutritional disorders in infancy and for evaluating the adequacy of treatment given during this important period of rapid growth. Total body fat (TBF) and fat-free mass (FFM) were estimated from total body electrical conductivity (TBEC) measurements in 423 healthy term Caucasian infants, aged 14-379 days. Cross sectional age, weight, and length related centile standards are presented for TBF and FFM. Centiles were calculated using Altman's method, based on polynomial regression and modelling of the residual variation. The TBF percentage steeply increased during the first half year of life, and slowly declined beyond this age. Various simple TBEC derived anthropometric prediction equations for TBF and FFM are available to be used in conjunction with these standards. Regression equations for the P50 and the residual SD, depending on age, weight, or length, are provided for constructing centile charts and calculating standard deviation scores.

Adipose Tissue↗