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Improved prediction of body fat by measuring skinfold thickness, circumferences, and bone breadths
(2005)
Objective: To develop improved predictive regression equations for body fat content derived from common anthropometric measurements. Research Methods and Procedures: 117 healthy German subjects, 46 men and 71 women, 26 to 67 years of age, from two different studies were assigned to a validation and a cross-validation group. Common anthropornetric measurements and body composition by DXA were obtained. Equations using anthropometric measurements predicting body fat mass (BFM) with DXA as a reference method were developed using regression models. Results: The final best predictive sex-specific equations combining skinfold thicknesses (SF), circumferences, and bone breadth measurements were as follows: BFMNew (kg) for men = -40.750 + {(0.397 x waist circumference) + [6.568 x (log triceps SF + log subscapular SF + log abdominal SF)]} and BFMNew (kg) for women = -75.231 + {(0.512 x hip circumference) + [8.889 x (log chin SF + log triceps SF + log subscapular SF)] + (1.905 x knee breadth)}. The estimates of BFM from both validation and cross-validation had an excellent correlation, showed excellent correspondence to the DXA estimates, and showed a negligible tendency to underestimate percent body fat in subjects with higher BFM compared with equations using a two-compartment (Durnin and Womersley) or a four-compartment (Peterson) model as the reference method. Discussion: Combining skinfold thicknesses with circumference and/or bone breadth measures provide a more precise prediction of percent body fat in comparison with established SF equations. Our equations are recommended for use in clinical or epidemiological settings in populations with similar ethnic background
The gastrointestinal glutathione peroxidase (GI-GPx, GPx2) is a selenoprotein that was suggested to act as barrier against hydroperoxide absorption but has also been implicated in the control of inflammation and malignant growth. In CaCo-2 cells, GI-GPx was induced by t-butyl hydroquinone (tBHQ) and sulforaphane (SFN), i.e., "antioxidants" known to activate the "antioxidant response element" (ARE) via electrophilic thiol modification of Keap1 in the Nrf2/ Keap1 system. The functional significance of a putative ARE in the GI-GPx promoter was validated by transcriptional activation of reporter gene constructs upon exposure to electrophiles (tBHQ, SFN, and curcumin) or overexpression of Nrf2 and by reversal of these effects by mutation of the ARE in the promoter and by overexpressed Keap1. Binding of Nrf2 to the ARE sequence in authentic gpx2 was corroborated by chromatin immunoprecipitation. Thus, the presumed natural antioxidants sulforaphane and curcumin may exert their anti-inflammatory and anticarcinogenic effects not only by induction of phase 2 enzymes but also by the up-regulation of the selenoprotein GI-GPx
Background: Estimating dietary intake is important for both epidemiological and clinical studies, but often lacks accuracy. Objective: To investigate the accuracy and validity of energy intake estimated by an easy-to-use semiquantitative food record (EISQFR) compared to total energy expenditure ( TEE) estimated by doubly labelled water technique (EEDLW). Design: TEE was measured in 29 nonobese subjects using the doubly labelled water method over a period of 14 days. Within this period, subjects reported their food consumption by a newly developed semiquantitative food record for 4 consecutive days. Energy intake was calculated using the German Food Code and Nutrition Data Base BLS II.3. Results: A good correlation was observed between EISQFR and EEDLW (r = 0.685, P<0.001). The mean difference between EISQFR and EEDLW was - 1.7 +/- 2.6 MJ/ day ( - 14 +/- 21%, P = 0.002). An underestimation of EISQFR <10% was observed in nine subjects (31%), of 10 - 20% in six subjects (21%), and of >20% in nine subjects (31%). In five subjects (17%), an overestimation of EISQFR was observed. Conclusions: The easy-to-use semiquantitative food record provided good estimates of EI in free-living and nonobese adults without prior detailed verbal instructions. The presented food record has limitations regarding accuracy at the individual level
INTRODUCTION: For obtaining reliable information about physical activity in epidemiological studies, validated and easy-to-use instruments are required. Therefore, a new simplified physical activity record based on 15-min recording intervals was developed and validated. SUBJECTS: Nonobese volunteers (n = 31). MEASUREMENTS: Physical activity was recorded over a 7-day period without detailed instructions. Energy expenditure was calculated (EEsPAR) and compared to energy expenditure measured by doubly labelled water technique (EEDLW). RESULTS: A good agreement between EEsPAR (12.1 +/ 3.0) and EEDLW (11.7 +/- 3.3) with a mean difference of 0.33 +/- 1.55 MJ (r = 0.880, P < 0.001) was observed. The absolute difference between EEsPAR and EEDLW was <10% in 65% of the subjects. The difference between EEsPAR and EEDLW was independent of gender, age, body weight, and body mass index. A weak positive association between the difference and total body fat was observed (r = 0.618, P < 0.001), suggesting a slight tendency to overestimate EEsPAR with increasing total body fat. CONCLUSION: The new simplified physical activity protocol needs no detailed instructions, provides valid estimates of physical activity in nonobese free-living adults and can be used in epidemiological studies to assess total daily energy expenditure and physical activity level
Background Soy protein is effective in lowering plasma cholesterol, LDL cholesterol and triglyceride concentrations. It has not been conclusively answered, whether and to what extent other soy constituents may also contribute to this effect. Objective To investigate the change in blood lipid levels after application of two soy-based supplements containing soy protein either without (SuproSoy(R)) or with (Abacor(R)) soy fiber and phospholipids in a randomized placebo-controlled triple-armed study. Methods 121 hypercholesterolemic adults ( 66 females, 55 males) were recruited and randomly assigned to one of three treatments. Over 8 weeks they received daily either 25 g soy protein ( as a component of the supplements Abacor(R) or SuproSoy(R)) or 25 g milk protein ( as a component of placebo). Serum lipids were measured at baseline and after 4, 6 and 8 weeks. Results After 8 weeks of supplementation total cholesterol levels were reduced by 8.0 +/- 9.6% (Abacor(R)) and 3.4 +/- 8.3% (SuproSoy(R)); LDL cholesterol levels by 9.7 +/- 11.7% ( Abacor(R)) and 5.4 +/- 11.6% ( SuproSoy(R)); and Apolipoprotein B levels by 6.9 +/- 14.6% (Abacor(R)) and 4.0 +/- 12.4 % (SuproSoy(R)). Serum levels of HDL cholesterol and triglycerides remained unchanged. Conclusions A preparation combining isolated soy protein with soy fibers and phospholipids showed twice the lipid-lowering effect of a preparation containing isolated soy protein alone. Therefore, such soy-based supplements can be useful in reducing the cardiovascular risk
Curcumin is a dietary compound with diverse anti-inflammatory and anticarcinogenic effects in several experimental models. A mechanism by which curcumin exerts these actions might be the direct modification of protein thiols, thereby altering the activity of the affected proteins. An early event in inflammatory signaling cascades is the recruitment of the interleukin-1 (IL-1) receptor-associated kinase (IRAK) to the IL-1 receptor (IL-1 RI) upon stimulation with IL-1. IRAK recruitment was shown recently to be inhibited by agents that modify thiols of IRAK. We asked, therefore, whether IRAK is also a target for curcumin. Curcumin indeed blocked IRAK thiols in a murine T-cell line stably overexpressing IRAK (EL-4(IRAK)), which resulted in the inhibition of IRAK recruitment to the IL-1RI and phosphorylation of IRAK and IL-1RI-associated proteins. Inhibitory effects were not reversible by thiol-reducing agents. Thus, modification by curcumin did not occur by oxidation but rather by alkylation, as is typical for electrophilic compounds reacting as Michael addition acceptors. The block in one of the earliest events in the IL-1 signaling cascade can explain the often observed inhibition of IL-1-mediated signaling steps by curcumin further downstream. Hence, thiol modification might be a crucial step in the anti-inflammatory functions of curcumin
Androgens and estrogens are transported bound to the sex hormone binding globulin (SHBG). SHBG is believed to keep sex steroids inactive and to control the amount of free hormones that enter cells by passive diffusion. Contrary to the free hormone hypothesis, we demonstrate that megalin, an endocytic receptor in reproductive tissues, acts as a pathway for cellular uptake of biologically active androgens and estrogens bound to SHBG. In line with this function, lack of receptor expression in megalin knockout mice results in impaired descent of the testes into the scrotum in males and blockade of vagina opening in females. Both processes are critically dependent on sex-steroid signaling, and similar defects are seen in animals treated with androgen- or estrogen-receptor antagonists. Thus, our findings uncover the existence of endocytic pathways for protein bound androgens and estrogens and their crucial role in development of the reproductive organs
Spectrofluorimetric studies have revealed that aflatoxin B-1 (AFB(1)) interacts with signal recognition particle (SRP), which acts as an escort for polyribosomes with signal peptides to be transported and bound to the cytoplasmic face of the endoplasmic reticulum (ER). We further report that the binding of AFB(1) to SRP is selective as it only binds to two (SRP9 and 14) out of its three constituent polypeptides studied. Binding of AFB(1) to proteins is known to alter their conformations. Interactions of AFB(1) with SRP polypeptides may generate structural and functional alterations in this particle and hinder secretory protein synthesis. Copyright (C) 2004 John Wiley Sons, Ltd
Bromelain was allowed to react with phenolic compounds. The activity and selected physico-chemical properties of the resulting derivatives were characterized. In vitro experiments showed that the proteolytic activity of bromelain was inhibited. Bromelain also serves as a food protein, because food stuffs based on pineapple contain relatively high concentrations of bromelain. In vitro digestion of bromelain derivatives with the main proteolytic enzymes of the gastrointestinal tract was also adversely affected. A covalent attachment of the phenolic compounds was identified at the tryptophan, free amino (lysines and N-terminal) and thiol groups of bromelain. A decrease in solubility of the derivatives was observed. The isoelectric point was shifted to lower pH values and high molecular weight fractions were identified. All effects observed depended on the reactivity of the phenolic substances. Two supplementary food products containing both bromelain and quercetin were also tested in terms of their proteolytic activity and digestibility
Xanthohumol (XN) is the principal prenylated flavonoid of the hop plant and has recently gained considerable interest due to its potential cancer-chemopreventive effects. However, the metabolism of XN has not yet been investigated in detail. Therefore, we studied the in vitro phase 11 metabolism of XN using nine human recombinant UDP- glucuronosyltransferases (UGT) and five sulfotransferases (SULT). The identification of the metabolites formed was elucidated using HPLC with diode array detection as well as HPLC/API-ES MS. XN was efficiently glucuronidated by UGT 1A8, 1A9, and 1A10; further important UGTs were UGT 1A1, 1A7, and 2B7. With respect to the sulfation reaction, SULT 1A1*2, 1A2, and 1E1 were the most active SULT forms. UGT 1A3, 1A4, and 1A6 as well as SULT 1A3 and 2A1 were of minor importance for the conjugation of XN. Three mono-glucuronides as well as three mono-sulfates were identified. Considering the tissue distribution of the tested UGT and SULT enzyme forms, these findings suggest a prominent role for the glucuronidation and sulfation of XN in the liver as well as in the gastrointestinal tract
The intention of this study was to increase the knowledge on the composition and structure of coffee bean proteins and the changes induced in them especially with regard to their interactions with the phenolic compounds also present. For this purpose green coffee beans were extracted by means of standard methanol extraction to quantify the chlorogenic acid content. Different solubilisation buffers were applied to extract the protein fractions with or without prior fat removal. The protein samples thus obtained were analysed by different methods (RP-HPLC, SDS-PAGE and SELDI-TOF- MS). Preliminary model studies were performed to characterize the interactions between the isolated green coffee protein fractions and chlorogenic acid (the major phenolic compound in coffee beans) with the intention of fulfilling the ultimate goal of characterizing such reactions in roasted coffee. The results show that the content of chlorogenic bound covalently to the protein increases. A reaction with the nucleophilic protein side chains (tryptophan, cystein and lysine) was recorded. Cross-inked protein polymers were also detected, whereby the a-chain was found to be more reactive. These reactions effect the solubility of the coffee bean proteins, the latter in turn becoming more acidic in nature. The secondary structure was affected only slightly as determined by circular dichroism. The in-vitro tryptic digestibility was also influenced, where again the cc-chain seems to be more susceptible. The observed polymerisation due to derivatisation by chorogenic acid declines the digestion. Similar digestion behaviour was also observed during tryptic hydrolysis of roasted coffee compared to that of green coffee, roasting allowing more stronger denaturation caused by the accompanying Maillard reaction. The derivatised green coffee bean proteins were found to have moderate antioxidative capacity
Appropriate animal models such as preruminant calves are necessary to study the complex physiological functions of carotenoids and to relate them to possible health effects in humans. In this study, the bioavailability and metabolism of lycopene from 2 dietary supplements were compared. LycoVit (R) containing synthetic lycopene and Lyc-O- Mato (R) containing natural tomato oleoresin were administered to 2 groups of preruminant calves (each n = 8) for 14 d in daily doses of 15 mg of lycopene. Plasma was analyzed for carotenoids before the intervention period, directly after, and each day for 5 d after the end of the intervention. All-trans and 5-cis lycopene, and 3 lycopene metabolites not previously found in calf plasma were detected. These metabolites contributed 52% of the total lycopene content measured at the end of the intervention period. Based on spectroscopic data, they might be hydrogenation products, which are formed from all-trans and/or 5-cis lycopene. In the LycoVit group, total lycopene concentrations were similar to 300% higher (286 +/- 89 nmol/L) than in the Lyc-O-Mato group (72 33 nmol/L) (P < 0.001). This indicates that, unlike in humans, lycopene from LycoVit and Lyc-O-Mato does not have equal bioavailabilities in preruminant calves. Therefore, the preruminant calf may not be a suitable animal model with which to study the biological and physiological effects of lycopene
Megalin-mediated reuptake of retinol in the kidneys of mice is essential for vitamin A homeostasis
(2005)
The reuptake of retinol (ROH) and retinol-binding protein (RBP) in the kidneys is mediated by the endocytic receptor megalin, suggesting an important role for this receptor in vitamin A (VA) metabolism. We examined the extent to which megalin deficiency may affect urinary ROH excretion, levels of ROH and RBP in plasma, as well as storage of VA in liver and kidney. For this purpose, mice with a kidney-specific megalin gene defect (megalin(lox/lox):; apoE(Cre)) and control mice (megalin(lox/lox)) were fed either a basal diet containing 4500 retinol equivalents (RE)/kg diet or a diet without VA during experimental periods of 42 and 84 d. Urinary ROH excretion was observed only in megalin(lox/lox); apoE(Cre) mice (P < 0.0001, 2-way ANOVA) and not in the controls. Plasma ROH and RBP differed only by diet (P < 0.05), but not genotype (P = 0.615). A major effect of megalin deficiency, however, was evident in retinyl ester levels in the liver (P < 0.05), which were similar to 37% lower than those in megalin(lox/lox) controls (P < 0.05, Student's t test) during the 84-d period of dietary VA deprivation. Kidney levels of VA were not affected by the receptor gene defect. The findings demonstrate that urinary ROH excretion caused by megalin deficiency requires accelerated mobilization of hepatic VA stores to maintain normal plasma ROH levels, which suggests that megalin plays an essential role in systemic VA homeostasis