Whole Body Protein Metabolism Estimated by 15N Tracer Experiments and Body Composition of Mice Selected for Different Growth Parameters

Abstract

Whole body protein synthesis was investigated in growing male mice which were long-time selected for high carcass protein amount (DU-6P, protein line) or for high body weight (DU-6, growth line) and in the unselected randomly bred control (DU-Ks). Six mice/line were housed singly in metabolic cages for the estimation of N balance, whole body protein synthesis (end-product method, single dose of ¹⁵N-labelled amino-acid mixture), and N distribution in the body. Another six mice/line were used for the determination of the body composition. All mice had free access to a commercial stock diet (crude protein 268 g, gross energy 19 MJ/kg dry matter) and to water. Body weight of both selection lines was about twice that of control mice at the same age. Selection for high body weight resulted in higher body fat content. Scaled to the corresponding body protein pools, the protein synthesis rates of selected mice were significantly higher than in controls, but were not significantly different between both selection lines in contrast to the protein deposition rates. The higher protein accretion in the protein line in comparison to the growth line seems to be due to a combination of a lower protein breakdown and an increased protein synthesis rate.     

Influence of Food Restriction and Compensatory Growth on Protein Synthesis and Breakdown in Growing Rats

The experiment was carried out with 24 male albino rats (5 weeks old, live weight 79 ± 5.1 g) divided into 2 groups. Gr. 1 (control group) was fed the commercial breeding food Ssniff with 22.4% crude protein ad lib., Gr. 2 (test group) for the first fortnight a mixture of the breeding food/cellulose 60/40 (restriction period) and subsequently for the second fortnight (compensatory period) also the breeding food ad lib. During both of these periods an 8 day N balance trial and a 4 day ¹⁵N tracer trial were included for estimation of growth rate and protein synthesis rate. Protein synthesis was ascertained by the endproduct method (oral application, single dose, mixture of 12 ¹⁵N-labelled amino acids); protein breakdown was calculated as the difference of protein synthesis rate and growth rate. The estimated rates were converted into fractional ones by referring to the body N content of corresponding animals. From the results of this experiment is concluded: The smaller N balance during moderate nutritional restriction can be attributed to a decrease of protein synthesis. The compensatory growth of the animals during the realimentation period is caused by an increase of protein synthesis and the enhanced protein conversion. Protein degradation is nearly unaffected.     

The measurement of muscle protein synthesis in broilers with a flooding dose technique: use of 15N-labelled phenylalanine, GC-MS and GC-C-IRMS

An experiment was carried out to measure fractional muscle protein synthesis rates (k(s)) in broilers with injection of a flooding dose of phenylalanine (1 ml/100 g body weight of 150 mM phenylalanine; 38 atom percent excess (APE) [15N]phenylalanine). K(s) was calculated from the [15N] enrichment in phenylalanine of tissue-free and protein-bound phenylalanine using both gas chromatography mass spectrometry (GC-MS) and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) for measurements after a 10 min isotope incorporation period. The tertiary-butyldimethylsilyl (t-BDMS) derivatives of phenylalanine were used for gas chromatographic separation in both systems. GC-MS and GC-C-IRMS were calibrated for a range of 7 to 37 [15N]APE and 0 to 0.62 [15N]APE, respectively, and for sample sizes of 0.45 to 4.5 nmol phenylalanine and 7 to 40 nmol phenylalanine, respectively. Reproducibility of standards as a measure of precision varied from 0.06 to 0.29 [15N]APE and from 0.0004 to 0.0018 [15N]APE in GC-MS and GC-C-IRMS, respectively. K(s) was measured in the m. pectoralis major of broilers fed rye based diets (56%) which were provided either unsupplemented (-) or supplemented (+) with an enzyme preparation containing xylanase. K(s) in breast muscles was significantly increased from 21.8%/d to 23.9%/d due to enzyme supplementation. It can be concluded from the study that the measurement of protein synthesis in broilers with the flooding dose technique can be carried out by using [15N]phenylalanine, GC-MS and GC-C-IRMS.     

The Influence of Feeding Frequency on Nitrogen Turnover and Whole Body Protein Synthesis in Adult Rats (Estimation using [14C]- and [15N]- Labelled Leucine)

Abstract

Male Wistar rats (17 wks. old, body weight ～400 g), fitted with an intra gastric cannula and with a catheter in the vena jugularis were divided into 3 groups and given a marginal ration of the feeding solution Nutrison Standard (1g protein and 350 kJ ME per day). Group 1 had ad lib. access to the drinking bottle, the groups 2 and 3 were pair fed by gastric infusion, splitted up into 2 greater meals for group 2 respectively into 6 smaller meals for group 3. After adaptation all animals get an i.p. injection of doubly labelled tracer solution (200μl) containing 2.5mg L-[¹⁵N]leucine (72 atom% ¹⁵N) combined with either [1-¹⁴C]- or [U-¹⁴C] leucine (37 kBq).

The course of ¹⁴CO₂ expiration was estimated by breath test over 4h in intervals of 15 min and the course of urinary ¹⁵N excretion over 24h in intervals of 45 resp. 90 min. An infusion of saline (0.9% 5ml/h) into the vena jugularis was used to provoke sustained urine production of the animals during the experiment.

From the parameters of the excretion curves of breath ¹⁴CO₂ resp. urine ¹⁵N (cumulative end value) and from the N balance the portions of leucine-C and leucine-N used for protein synthesis, transamination decarboxylation and total oxidation as well as the kinetic parameters for whole body protein metabolism were computed.

The following conclusions were drawn:

6 x feeding regime produces a small but measurable amino acid economy effect in comparison to 2 x feeding regime.

Protein gain for 2 x feeding group was significant smaller than for 6 x feeding group, though protein synthesis rate was higher, but was overcompensated by a greater increase of protein breakdown rate for the 2 x feeding group. Energy storage in form of fat and glycogen built from decarboxylation was unaffected by feeding frequency. The amount of leucine oxidized for heat production was 4% higher for the 6 x feeding group. Transamination rate for leucine was estimated to 8–15%. Absolute values for protein flux, protein synthesis and protein breakdown may be overestimated or underestimated because the metabolism of [¹⁵N] leucine does not exactly agree with that of total N; but the proportions of them and therefore also the conclusions will be true. Better results for absolute values will be obtained using a mixture of ¹⁵N labelled AA, ¹⁵N labelled protein or hydrolysate of ¹⁵N labelled protein (yeast) as the tracer source.     

Metabolic effects of HAY's diet

The aim of the study was, to evaluate the metabolic effect of HAY's diet on protein turnover, fat oxidation, respiratory quotient, body fat and weight loss. Twelve healthy adults received an individually regular diet and thereafter a corresponding isocaloric and isonitrogenous 10-day HAY-diet. Protein turnover and 13C-fat oxidation were investigated after administration of [15N]glycine and an [U-13C]algae lipid mixture. The 15N and 13C enrichment in urine and breath were measured by isotope ratio mass spectrometry. The respiratory quotient was measured by indirect calorimetry. Body fat, total body water and lean body mass were estimated by bio-electric impedance analysis. HAY's diet led to a significantly higher 13C-fat oxidation (15.4 vs. 22.0% P < 0.01), corresponding to a lower respiratory quotient (0.88 vs. 0.81; P < 0.01), whereas the protein turnover remained constant in both diets (3.06 vs. 3.05 g/kg/day). HAY's diet did not reduce total body water, lean body mass, body fat and body weight (72.2 vs. 71.4 kg).     

稀土元素原子发射光谱及其谱线干扰的高分辨率ICP-AES研究——Ⅵ.镧、铽、钬、铒基体对其他稀土元素的光谱干扰

利用光栅刻线为3600条／mm的高分辨率时序扫描式ICP－AES光谱仪研究镧(La）、铽（Tb）、钬（Ho)、铒（Er)基体分别对其他14个稀土元素共65条“首选分析线”的光谱干扰情况,获得了相应的光谱干扰轮廓和稀土光谱干扰信息,为选择在该4种稀土基体中的其他稀土元素ICP－AES最佳分析线提供了参考。     

The Measurement of Muscle Protein Synthesis in Broilers with a Flooding Dose Technique: Use of 15N-Labelled Phenylalanine,GC-MS and GC-C-IRMS

Abstract

An experiment was carried out to measure fractional muscle protein synthesis rates (k _s ) in broilers with injection of a flooding dose of phenylalanine (1 ml/100 g body weight of 150 mM phenylalanine; 38 atom percent excess (APE) [¹⁵N]phenylalanine). K _s was calculated from the [¹⁵N] enrichment in phenylalanine of tissue-free and protein-bound phenylalanine using both gas chromatography mass spectrometry (GC-MS) and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) for measurements after a 10 min isotope incorporation period.

The tertiary-butyldimethylsilyl (t-BDMS) derivatives of phenylalanine were used for gas chromatographic separation in both systems. GC-MS and GC-C-IRMS were calibrated for a range of 7 to 37 [¹⁵N]APE and 0 to 0.62 [¹⁵N]APE, respectively, and for sample sizes of 0.45 to 4.5 nmol phenylalanine and 7 to 40 nmol phenylalanine, respectively. Reproducibility of standards as a measure of precision varied from 0.06 to 0.29 [¹⁵N]APE and from 0.0004 to 0.0018 [¹⁵N]APE in GC-MS and GC-C-IRMS, respectively.

K _s was measured in the m. pectoralis major of broilers fed rye based diets (56%) which were provided either unsupplemented (-) or supplemented (+) with an enzyme preparation containing xylanase. K _s in breast muscles was significantly increased from 21.8%/d to 23.9%/d due to enzyme supplementation.

It can be concluded from the study that the measurement of protein synthesis in broilers with the flooding dose technique can be carried out by using [¹⁵N]phenylalanine, GC-MS and GC-C-IRMS.     

Single loop multi-gap resonator for whole body EPR imaging of mice at 1.2 GHz

For whole body EPR imaging of small animals, typically low frequencies of 250-750 MHz have been used due to the microwave losses at higher frequencies and the challenges in designing suitable resonators to accommodate these large lossy samples. However, low microwave frequency limits the obtainable sensitivity. L-band frequencies can provide higher sensitivity, and have been commonly used for localized in vivo EPR spectroscopy. Therefore, it would be highly desirable to develop an L-band microwave resonator suitable for in vivo whole body EPR imaging of small animals such as living mice. A 1.2 GHz 16-gap resonator with inner diameter of 42 mm and 48 mm length was designed and constructed for whole body EPR imaging of small animals. The resonator has good field homogeneity and stability to animal-induced motional noise. Resonator stability was achieved with electrical and mechanical design utilizing a fixed position double coupling loop of novel geometry, thus minimizing the number of moving parts. Using this resonator, high quality EPR images of lossy phantoms and living mice were obtained. This design provides good sensitivity, ease of sample access, excellent stability and uniform B(1) field homogeneity for in vivo whole body EPR imaging of mice at 1.2 GHz.     

Whole-body protein turnover in nephrotic subjects: a comparison between different degrees of proteinuria

In contrast to the increased hepatic albumin synthesis in subjects with proteinuria, little is known about the corresponding whole-body protein turnover rates (WPTR). The WPTR and the reutilisation rates (R) were investigated in 20 patients divided in three groups of different degrees of proteinuria (groups I-III: < 1, 1-3, > 3 g/m2/day, respectively). [15N]glycine was administered as a single oral pulse. Urine samples were taken over 2 days. After removing urinary proteins by trichloracetic acid, 15N-enrichment in the supernatant was measured by isotope ratio mass spectrometry. A three-compartment model was used to calculate WPTR and R, which showed a statistically significant difference between groups I and III (2.64 vs. 4.63 g/kg/day, and 70.4% vs. 80.8%, respectively, P < 0.01), whereas the net protein gain remained unchanged (0.13 vs. 0.22 g/kg/day). The higher the protein loss the higher the WPTR and the corresponding R. The severe protein loss provokes increased WPTR and R as well.     

Temporal and preparation effects in the magnetic nanoparticles of Apis mellifera body parts

Magnetic nanoparticles in the Apis mellifera abdomens are well accepted as involved in their magnetoreception mechanism. The effects of sample preparation on the time evolution of magnetic particles in the honeybee body parts (antennae, head, thorax and abdomen) were investigated by Ferromagnetic Resonance (FMR) at room temperature (RT), for about 100 days. Three preparations were tested: (a) washed with water (WT); (b) as (a), kept in glutaraldehyde 2.5% in 0.1 M cacodylate buffer (pH 7.4) for 24 h and washed with cacodylate buffer (C); (c) as (a), kept in glutaraldehyde 2.5% for 24 h and washed with glutaraldehyde 2.5% in cacodylate buffer (GLC). The four body parts of young and adult worker presented magnetic nanoparticles. The Mn²⁺ lines are observed except for the antennae spectra. The high field (HF) and low field (LF) components previously observed in the spectra of social insects, are confirmed in these spectra. The HF line is present in all spectra while the LF is easily observed in the spectra of the young bee and it appears as a baseline shift in spectra of some adult parts. The HF intensity of the abdomen is commonly one order of magnitude larger than any other body parts. This is the first systematic study on the conservation of magnetic material in all body parts of bees. The results show that the time evolution of the spectra depends on the body part, conserving solution and bee age. Further measurements are necessary to understand these effects and extend it to other social insects.     

Differential inhibition of postnatal brain,spinal cord and body growth by a growth hormone antagonist

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.     

Advance in diagnostics for high-temperature plasmas based on the analytical result for the ion dynamical broadening of hydrogen spectral lines

It is well known that the ion dynamics is very important for Stark broadening of spectral lines in high-T plasmas. However, it is usually assumed that with the increase of the plasma density N and/or of the principal quantum number n of the upper level of the radiator, the ionic contribution to the impact width (ICIW) tends to zero. In distinction to that paradigm, by finding an analytical result for the ion dynamical broadening of hydrogen spectral lines, we show here that with the increase of N and/or n, the ICIW does not decrease. Moreover, for practically important ranges of T, N, and n, this "residual" ICIW, being virtually independent of n, can be comparable to the standard electron impact width. This result leads to: (i) a substantial revision of the past of diagnostic conclusions for a variety of high-T plasma experiments; (ii) a much better possibility to deduce from experimental, Stark-broadened line profiles not only the plasma density but also the plasma temperature; (iii) a significant enhancement of the accuracy of N and T obtained from experimental line profiles; and (iv) a substantial revision of simulation models for the ion dynamical contribution that were based on a wrong assumption that the latter vanishes under increasing N and/or n. The consequences are especially important for tokamak plasmas, where the diagnostics based on experimental profiles of high Balmer and Paschen lines is frequently used.     

介质阻挡放电中亮暗点放电的谱线线形及振动温度

在氩气/空气的混合气体介质阻挡放电中,首次在高温条件下观察到亮点和暗点共存的放电,比较了中心亮点及四周暗点放电的谱线频移,并测量了它们的振动温度。实验采用氩原子ArⅠ(2P2→1S5)的发射谱线测量谱线频移,采用氮分子第二正带系(C3Πu→B3Πg)的发射谱线测量振动温度。结果表明:中心亮点放电中的ArⅠ(2P2→1S5)谱线的频移大于四周的暗点放电谱线的频移,表明前者电子密度较高;四周的暗点的放电振动温度高于中心亮点放电的振动温度。     

稀土元素原子发射光谱及其谱线干扰的高分辨率ICP—AES研究： …

本文是系列工作的第四部分。利用光栅刻线为３６００条／ｍｍ的顺序扫描高分辨率ＩＣＰ－ＡＥＳ光谱仪研究了铕和钆分别作为基体时对其他１４个元素共６６条“首选分析线”的光谱干扰情况,获得了相应的光谱干扰轮廓和其他光谱干扰信息,为选择不同稀土基体中的稀土元素最佳分析线提供了有益的参考依据。     

压强对介质阻挡放电中八边形结构等离子体温度的影响

利用水电极介质阻挡放电装置,在氩气和空气的混合气体中,首次观察到了由点和线组成的八边形结构。采用发射光谱法,研究了八边形结构中的点和线的等离子体温度随压强的变化关系。利用氮分子第二正带系(C3Π_u→B3Π几_g)的发射谱线,计算了点和线的分子振动温度;通过氮分子离子391.4 nm和氮分子394.1 nm两条发射谱线的相对强度比,研究了点和线的电子平均能量大小变化;利用氩原子763.26 nm(2P₆→1S₅)和772.13 nm(2P₂→1S₃)两条谱线强度比法,得到了点和线的电子激发温度。实验发现：在同一压强条件下,线比点的分子振动温度、电子平均能量以及电子激发温度均高;随着气体压强从40 kPa增大到60 kPa,点和线的分子振动温度、电子平均能量以及电子激发温度均减小。     

Tuning of Lower Critical Solution Temperature (LCST) of Poly(N-Isopropylacrylamide-co-Acrylic acid) Hydrogels

Temperature-responsive hydrogel with a lower critical solution temperature (LCST) close to human body temperature was prepared. Crosslinked N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) copolymer networks were synthesized at various monomer ratios in the presence of ammonium persulfate (APS), N,N′-methylenebisacrylamide (NMBA) and N,N,N′,N′-tetramethylethylenediamine (TEMED) via a redox polymerization method. The resulting hydrogels possessed thermo- and pH-responsive characteristics. They were characterized in terms of swelling ratio, volume change, water uptake and diffusivity, water vapor uptake and diffusivity, and phase transition temperature. The water liquid and vapor diffusion coefficients for all the synthesized hydrogels were higher than the literature data, implying higher rates for drug release. The LCST of the hydrogel increased with higher AAc content in the copolymer. The gel containing 1.8% AAc exhibited an LCST similar to human body temperature, demonstrating a potential use in drug controlled release and biomedical applications.     

Metabolic Effects of HAY's Diet

Abstract

The aim of the study was, to evaluate the metabolic effect of HAY's diet on protein turnover, fat oxidation, respiratory quotient, body fat and weight loss. Twelve healthy adults received an individually regular diet and thereafter a corresponding isocaloric and isonitrogenous 10-day HAY-diet. Protein turnover and ¹³C-fat oxidation were investigated after administration of [¹⁵N]glycine and an [U-¹³C]algae lipid mixture. The ¹⁵N and ¹³C enrichment in urine and breath were measured by isotope ratio mass spectrometry. The respiratory quotient was measured by indirect calorimetry. Body fat, total body water and lean body mass were estimated by bio-electric impedance analysis. HAY's diet led to a significantly higher ¹³C-fat oxidation (15.4 vs. 22.0% P < 0.01), corresponding to a lower respiratory quotient (0.88 vs. 0.81; P < 0.01), whereas the protein turnover remained constant in both diets (3.06 vs. 3.05 g/kg/day). HAY's diet did not reduce total body water, lean body mass, body fat and body weight (72.2 vs. 71.4 kg).     

Studies on Body Composition in Irradiated Mice

A total of 40 male and 40 female mice of equal body weight were used in the present study. Whole body gamma (⁶⁰Co) irradiation was carried out at 400, 800 and 1200 rad. Life span and several parameters of body composition were measured. Cumulative mortality precentage was lower in irradiated females in comparison to males. Ionizing radiation induced reduction (P < 0.01) in body weight, total body water with its two compartments (extra-and intracellular), fat-free body with its component (body cell mass and extracellular tissue), fat-free dry solids with its constituent (body protein and body ash), body potassium and body fat. While all of the above mentioned body composition parameters decreased (P ≤ 0.01) following whole body irradiation, the rations between the body water to these parameters increased (P ≤ 0.01). Sex difference was noticed either for the parameters or for the ratios.     

Three body clusters in finite nuclei (I). 4He

A method is developed for the treatment of the Bethe-Faddeev three body cluster equations in finite nuclei. A matrix method is employed to sum the three hole line graphs in ⁴He. For each value of a constant shift C in the intermediate state oscillator spectrum we have calculated: (i) the two body bound state binding energy self-consistently in the Brueckner approximation, (ii) the energy contribution from three hole line graphs, and (iii) the effect of single particle potential insertion in particle lines. The most important dependence on C comes from those graphs containing single particle insertions and their effect is to make the sum of (i) + (ii) + (iii) much less dependent upon C than (i) alone. The three hole line contribution for ⁴He comes mainly from third order graphs. Effects of truncation of the matrix are severe and calculations with a larger matrix could alter the quantitative but probably not the qualitative results.     

基于相关子空间的双峰发射线光谱特征提取与分析

低分辨率天体光谱中呈现的双峰发射线轮廓可能反映着比较珍稀的物理现象,如双活动星系核（AGNs）、双超大质量黑洞（SMBH）、喷流云与窄线区的相互作用,也可能是光谱处理过程产生的低质量特征线。双峰发射线轮廓一般由2个或2个以上的波峰构成,对该特征进行提取并分析,可作为双AGN、星系对、双黑洞等稀有天体更有效的搜寻依据,从而有助于更深入地研究星系乃至宇宙的形成与演化。提出一种新的基于相关子空间的双峰发射线特征提取与分析方法,主要工作分为以下三部分：首先利用稀疏差异因子δ度量双峰发射线光谱中属性差异程度,利用KNN方法约束参与稀疏差异因子计算的光谱范围,在此基础上,针对LAMOST低分辨率光谱给出基于相关子空间的特征提取方法;其次,为了验证稀疏差异因子σ以及KNN的输入参数k对双峰发射线光谱的适应性,选择LAMOST双峰发射线光谱样本及普通星系光谱数据,红移范围z<0.3（确保Hα,Hβ,[OⅢ]λλ4 959, 5 007,[NⅡ]λλ6 548, 6 584,[SⅡ]λλ6 717, 6 731等发射线落在LAMOST波长覆盖范围）,获得训练集光谱总数332+332（正负样本）条,并借助人眼检查分析该方法中的两个参数：k和δ阈值α对结果的影响,实验表明,当k=18,α=0.6时,相关属性分布较密集且稀疏点较少,结果比较理想;最后,对332条双峰发射线光谱特征子空间所在的波长区间、双峰红/蓝移间隔、双峰线强比等进行了理论分析、测量及人眼认证的基础上,给出了基于相关子空间的双峰发射线特征表述。此外,从双峰特征子空间上不同的发射线激发机制（[OⅢ]/[NⅡ]/[SⅡ]等禁线、Hα、Hβ等氢线）及相关特征子空间上线强关系等角度,对样本中双峰轮廓进行了分析。