Human lactation: oxidation and maternal transfer of dietary 13C-labelled α-linolenic acid into human milk

The origin of fatty acids in milk has not been elucidated in detail. We investigated the contribution of dietary α-linolenic acid (ALA) to human milk fat, its oxidation and endogenous conversion to long-chain polyunsaturated fatty acids. Ten lactating women were given ¹³C-ALA orally, and breath and milk samples were collected for a five-day period, while dietary intakes were assessed. 37.5?±?2.7?% (M?±?SE) of the tracer was recovered in breath-CO₂, and 7.3?±?1.1?% was directly transferred into milk. About 0.25?% of the tracer was found in milk long-chain polyunsaturated fatty acids. Combining intake and milk data, we estimate that about 65?% of milk ALA is directly derived from maternal diet. Thus, the major portion of milk ALA is directly derived from the diet, but dietary ALA does not seem to contribute much as a precursor to milk n-3 long-chain polyunsaturated fatty acids within the studied time period.     

Effect of sugars on liquid-vapour partition of volatile compounds in ready-to-drink coffee beverages

The effect of sugars (sucrose, lactose, glucose, fructose, 10%w/v) on the liquid-vapour partition of selected volatile compounds of coffee beverages has been investigated in espresso coffee and ready-to-drink (RTD) canned coffee prepared and obtained by using the same Arabica roasted coffee beans blend. Aroma composition of coffee beverages has been preliminary investigated by headspace-gas chromatography (HS-GC) and solid phase microextraction-HS-GC-mass spectrometry to characterize the volatile pattern of the systems and to evaluate the effects of sugars on the aroma release/retention. Then, the liquid-vapour partition coefficient (k) of 4 selected key aroma compounds (diacetyl, 2,3-pentanedione, ethylpyrazine, hexanal) was determined in water, sugars solutions as well as RTD coffee brews added with the same sugars (10%w/v). Sugars added in coffee beverages affected the release of the volatiles and thus its aroma profile with differences due to the type of added sugar and coffee brew type. The k values of the selected volatile compounds resulted different depending on the model system composition (water, coffee brew) and sugar type added. In particular, melanoidins as well as other non-volatile components (lipids, acids, carbohydrates) in the RTD coffee brews could be implied in the change of k of the volatile compounds in respect to that observed in water. The effects of the sugar type on the release/retention of the four key coffee aroma compounds were partly explained in terms of 'salting out' especially for the more polar volatile compounds and in the sucrose-added model systems. The change of chemical and physico-chemical properties of the water and brews induced by the sugars as well as the occurrence of interactions between volatile compounds and non-volatile components may be implied in the reduction of the vapour partition of the aroma compounds. Copyright ? 2012 John Wiley & Sons, Ltd.     

Field-deployable measurements of free-living individuals to determine energy balance: fuel substrate usage through δ13C in breath CO2 and diet through hair δ13C and δ15N values

Carbon isotopes of breath CO₂ vary depending on diet and fuel substrate used. This study examined if exercise-induced δ¹³C-CO₂ changes in substrate utilization were distinguishable from baseline δ¹³C-CO₂ variations in a population with uncontrolled diet, and compared hair isotope values and food logs to develop an isotope model of diet. Study participants included nine women with diverse Body Mass Index (BMI), age, ancestry, exercise history, and diet. Breath samples were collected prior to and up to 12?h after a 5- or 10?K walk/run. Indirect calorimetry was measured with a smartphone-enabled mobile colorimetric device, and a field-deployable isotope analyzer measured breath δ¹³C-CO₂ values. Diet was assessed by food logs and δ¹³C, δ¹⁵N of hair samples. Post-exercise δ¹³C-CO₂ values increased by 0.54?±?1.09‰ (1 sd, n?=?9), implying enhanced carbohydrate burning, while early morning δ¹³C-CO₂ values were lower than daily averages (p?=?0.0043), indicating lipid burning during overnight fasting. Although diurnal δ¹³C-CO₂ variation (1.90?±?0.77‰) and participant baseline range (3.06‰) exceeded exercise-induced variation, temporal patterns distinguished exercise from dietary isotope effects. Hair δ¹³C and δ¹⁵N values were consistent with a new dietary isotope model. Notwithstanding the small number of participants, this study introduces a novel combination of techniques to directly monitor energy balance in free-living individuals.     

AVPV neurons containing estrogen receptor-beta in adult male rats are influenced by soy isoflavones

Background  

Isoflavones, the most abundant phytoestrogens in soy foods, are structurally similar to 17beta-estradiol. It is known that 17beta-estradiol induces apoptosis in anteroventral periventricular nucleus (AVPV) in rat brain. Also, there is evidence that consumption of soy isoflavones reduces the volume of AVPV in male rats. Therefore, in this study, we examined the influence of dietary soy isoflavones on apoptosis in AVPV of 150 day-old male rats fed either a soy isoflavone-free diet (Phyto-free) or a soy isoflavone-rich diet (Phyto-600).     

Dietary fibre-rich resistant starches promote ammonia detoxification in the human colon as measured by lactose-[15N2]ureide

Three resistant starches (RSs), namely fibre of potatoes (FP), wrinkle pea starch (WPS), and high amylose maize starch (HAMS) with different dietary fibre contents, were supplemented in adults to evaluate their effects on urinary nitrogen and ammonia excretion as well as on faecal nitrogen excretion by means of lactose-[¹⁵N₂]ureide (¹⁵N-LU) degradation. Twenty subjects received a regular diet either without or with the supplementation of FP, WPS, and HAMS in a randomized order. After administration of ¹⁵N-LU, urine and faeces were collected over 48 and 72 h, respectively, whereas blood was collected after 6 h. The ¹⁵N-abundances were measured by isotope ratio mass spectrometry. In comparison to the dry run, supplementation with RS significantly lowered renal ¹⁵N-excretion (dry run: 43.2?%, FP: 34.6?%, WPS: 37.9?%, HAMS: 36.4?%) as well as the corresponding ¹⁵NH₃-excretion (dry run: 0.08?%, FP: 0.06?%, HAMS: 0.05?%), clearly indicating a reduced colonic nitrogen generation at high dietary fibre intake.     

Real-time monitoring of ethane in human breath using mid-infrared cavity leak-out spectroscopy

We report on spectroscopic real-time analysis of ethane traces in exhaled human breath. Ethane is considered the most important volatile marker of free-radical induced lipid peroxidation and cell damage in the human body. Our measurements were carried out by means of mid-infrared cavity leak-out spectroscopy in the 3 μm region, a cw variant of cavity ring-down spectroscopy. The spectrometer is based on a CO overtone laser with tunable microwave sidebands. The resulting system proved to be an unique tool with high sensitivity and selectivity for rapid and precise breath testing. With a 5 s integration time, we achieved a detection limit on the order of 100 parts per trillion ethane in human breath. Thus, sample preconcentration is unnecessary. Time-resolved monitoring of the decaying ethane fraction in breath after smoking a cigarette is demonstrated. Received: 13 March 2001 / Published online: 9 May 2001     

Effects of ergot alkaloids on liver function of piglets can be detected by the [(13)C]methacetin breath test irrespective of oral or intramuscular route of tracer administration

Ergot alkaloids (sum=total alkaloids, TA) originate from the phyto-pathogenic fungus Claviceps purpurea and might exert feed intake depressing and hepatotoxic effects on animals. The aim of the study was to evaluate TA effects on performance and liver function of piglets with the [(13)C]methacetin breath test and two routes of tracer administration (orally, p.o.; intramuscularly, i.m.). Two ergot batches were mixed into piglet diets resulting in 21 and 17?mg?TA?kg(-1) (Ergot-5 and -12, respectively) and compared with an ergot-free control diet. Feed intake was significantly depressed after feeding the ergot containing diets (p=<0.001). The time at maximum (13)CO(2) exhalation (t (max)) and the half-life (t (0.5)) were not influenced by treatments and varied between 25 and 68 min after the p.o., and 28 and 62 min after the i.m. administration of [(13)C]methacetin, respectively. The cumulative (13)C recovery (cPDR(30)) was significantly lower due to feeding the diet Ergot-5 (6.6 %) compared with the Ergot-12 (8.8 %) and the control diet (9.7 %) irrespective of the route of tracer administration (p=0.044). As a discrimination of the diet effects through both tracer administration routes is possible, the i.m. application should be preferred in piglets as this causes less stress than the oral forced administration.     

Liver function assessment with three (13)C breath tests by two-point measurements

In this study, we performed three breath tests - l-[1-(13)C ]phenylalanine breath test (PBT), l-[1-(13)C ] methionine breath test, and [(13)C]methacetin breath test (MethaBT) - in patients with chronic liver disease to determine the optimal timing of expired air collection for diagnosing chronic liver disease and evaluating the grade of fibrosis. The subjects were 61 adults with normal livers, 98 chronic hepatitis patients, and 91 liver cirrhosis patients. We investigated the relationships of breath test results with routine biochemical tests and the Child-Pugh score, as well as the diagnostic capacities of the breath tests for liver dysfunction/cirrhosis and grade of liver fibrosis. For the diagnosis of liver cirrhosis and correlations with liver fibrosis, the accuracy of the PBT at 30 min (PBT30) was similar to that of the MethaBT at 15 min (Metha15). For liver function assessment by two-point measurement with (13)C breath tests, we recommend the PBT30 and the Metha15.     

Disturbed oscillatory brain dynamics in subcortical ischemic vascular dementia

Background

This study examined the effects of dietary polyunsaturated fatty acids (PUFA) as different n-6: n-3 ratios on spatial learning and gene expression of peroxisome- proliferator-activated receptors (PPARs) in the hippocampus of rats. Thirty male Sprague?CDawley rats were randomly allotted into 3 groups of ten animals each and received experimental diets with different n-6: n-3 PUFA ratios of either 65:1, 22:1 or 4.5:1. After 10?weeks, the spatial memory of the animals was assessed using the Morris Water Maze test. The expression of PPAR?? and PPAR?? genes were determined using real-time PCR.

Results

Decreasing dietary n-6: n-3 PUFA ratios improved the cognitive performance of animals in the Morris water maze test along with the upregulation of PPAR?? and PPAR?? gene expression. The animals with the lowest dietary n-6: n-3 PUFA ratio presented the highest spatial learning improvement and PPAR gene expression.

Conclusion

It can be concluded that modulation of n-6: n-3 PUFA ratios in the diet may lead to increased hippocampal PPAR gene expression and consequently improved spatial learning and memory in rats.     

Liver function assessment with three 13C breath tests by two-point measurements

In this study, we performed three breath tests – l-[1-¹³C ]phenylalanine breath test (PBT), l-[1-¹³C ] methionine breath test, and [¹³C]methacetin breath test (MethaBT) – in patients with chronic liver disease to determine the optimal timing of expired air collection for diagnosing chronic liver disease and evaluating the grade of fibrosis. The subjects were 61 adults with normal livers, 98 chronic hepatitis patients, and 91 liver cirrhosis patients. We investigated the relationships of breath test results with routine biochemical tests and the Child–Pugh score, as well as the diagnostic capacities of the breath tests for liver dysfunction/cirrhosis and grade of liver fibrosis. For the diagnosis of liver cirrhosis and correlations with liver fibrosis, the accuracy of the PBT at 30 min (PBT30) was similar to that of the MethaBT at 15 min (Metha15). For liver function assessment by two-point measurement with ¹³C breath tests, we recommend the PBT30 and the Metha15.     

Absolute quantification of the hepatic glycogen content in a patient with glycogen storage disease by C magnetic resonance spectroscopy

Using natural-abundance ¹³C magnetic resonance spectroscopy (MRS) on a conventional whole-body system operating at 1.5 T, the absolute hepatic glycogen concentration was noninvasively determined in a patient with type Ia glycogen storage disease. Furthermore, to assess the reliability of glycogen determination, hepatic glycogen content was assessed after an overnight fasting period in 35 healthy volunteers divided into two groups, one with a carbohydrate-rich diet, the other without any particular dietary preparation. In the patient, the glycogen concentration was found to be 458 mM. In the healthy subjects, average glycogen concentrations were 229 ± 34 mM (mean ± standard deviation) and 257 ± 31 mM for the group without and with dietary preparation, respectively. The ¹³C-MRS results are in agreement with those obtained by conventional liver biopsy. ¹³C MRS in natural abundance may thus serve as a straightforward, fast, and noninvasive tool for quantification of the liver glycogen content in patients.     

Detection of dimethyl sulfone in the human brain by in vivo proton magnetic resonance spectroscopy

We wish to report the detection of dimethyl sulfone (methylsulfonylmethane, C2H6O2S) in the brain of a normal 62-year-old male using in vivo proton magnetic resonance spectroscopy. The presence of this exogenous metabolite resulted from ingestion of a dietary supplement containing dimethyl sulfone. The concentration of this compound in the brain was measured to be 2.4 mmol, with a washout "half life" of approximately 7.5 days. The in vivo T1 and T2 relaxation times of dimethyl sulfone were measured to be 2180 ms and 385 ms, respectively. The concentration of major brain metabolites, namely N-acetylaspartate, total Creatine and Choline, and myo-Inositol were within normal limits.     

Experimental study on electrostatic removal of high-carbon particle in high temperature coal pyrolysis gas

A high-temperature electrostatic precipitator (ESP) presents a good solution for hot gas cleaning, which can remove fly ash from pyrolysis gas at temperatures higher than the tar dew point. In this paper, the characteristics of negative DC corona discharge in air and simulated coal pyrolysis gas were studied. The removal of coal pyrolysis furnace fly ash (ash A) was investigated and compared with that of coal-fired power plant fly ash (ash B) in ESP with a temperature ranging from 300?K to 900?K. The current density of simulated gas was higher than that of air under the same discharge voltage and at different temperatures. The simulated gas also had a higher spark voltage and a lower onset voltage compared with air. The fractional collection efficiency of ash A was lower for particles with diameters of larger than 0.1?µm at high temperature, compared with ash B. A lower collection efficiency in simulated gas was obtained for particles with diameters of less than 0.1?µm compared with air. The collection efficiency of submicron particles in simulated gas was usually higher than it in air, especially for particles with diameters of less than 0.04?µm. In simulated gas, the overall collection efficiency of ash A was obviously lower than that of ash B, especially at high temperature. From 300?K to 700?K, the collection efficiencies of both ash samples were as high as above 93%, but the collection efficiency of ash A in simulated gas decreased to 78.7% at 900?K.     

Scrutiny of 13C-phenylalanine breath test reproducibility

We evaluated the reproducibility of the ¹³C-phenylalanine breath test (¹³C-PheBT). On three separate days, 21 healthy volunteers (11 F and 10 M) underwent ¹³C-PheBT with 100 mg l-[1-¹³C]phenylalanine taken orally. Short-term reproducibility was evaluated with paired examinations taken 3 days apart; paired examinations separated by 23 days (median) served for the medium-term reproducibility assessment. Expiratory air was sampled at 19 points throughout 3?h. Determined limited reproducibility of the ¹³C-PheBT must be taken into consideration while interpreting the results of this diagnostic tool. The results of this study imply the following conclusions: (i) From among the three parameters examined, the cumulative ¹³C recovery area under the curve (AUC) offers much better reproducibility than the maximum momentary ¹³C recovery in the expiratory air (D_max) or the time to reach the maximum momentary ¹³C recovery (T_max) (ii) Collection of the breath air samples for 2?h results in a much better reproducibility of AUC, than for 1?h only; (iii) Reproducibility of ¹³C-PheBT is affected neither by the duration of the time gap between repeated tests nor by gender; (iv) Comparison with data obtained formerly reveals that reproducibility of the ¹³C-PheBT is worse than either that of of the ¹³C-methacetin (¹³C-MBT) or the ¹³C-alpha-ketoisocaproic acic (¹³C-KICA-BT) breath tests. This finding will have to be taken into consideration while interpreting the results of this diagnostic tool.     

基于激光感生电压技术的咖啡粉粒径检测

咖啡颗粒的大小直接影响着成品咖啡的品质,高效辨别出咖啡粉粒径大小对咖啡品质的鉴别尤其重要。在89 μm～140 μm粒径范围内,利用激光感生电压（laser-induced voltage,LIV）技术对不同粒径的云南小颗粒咖啡粉进行检测,不同粒径咖啡粉展现出不同的LIV响应,其信号幅值、响应时间、半高宽等参数均存在明显差异。随咖啡粉粒径逐渐增大,其LIV信号幅值（V_p）呈先减小后增大的趋势,当粒径为104 μm～107 μm时V_p最小。此外,LIV信号波形的响应时间及半高宽分别与咖啡粉末粒径之间呈正、负相关变化规律。结果表明,激光感生电压技术对咖啡粉粒径的变化较为敏感,有望成为检验咖啡粉粒径的有效检测手段。     

Increased strontium uptake in trabecular bone of ovariectomized calcium‐deficient rats treated with strontium ranelate or strontium chloride

Based on clinical trials showing the efficacy to reduce vertebral and non‐vertebral fractures, strontium ranelate (SrR) has been approved in several countries for the treatment of postmenopausal osteoporosis. Hence, it is of special clinical interest to elucidate how the Sr uptake is influenced by dietary Ca deficiency as well as by the formula of Sr administration, SrR versus strontium chloride (SrCl₂). Three‐month‐old ovariectomized rats were treated for 90 days with doses of 25 mg kg^?1 d^?1 and 150 mg kg^?1 d^?1 of SrR or SrCl₂ at low (0.1% Ca) or normal (1.19% Ca) Ca diet. Vertebral bone tissue was analysed by confocal synchrotron‐radiation‐induced micro X‐ray fluorescence and by backscattered electron imaging. Principal component analysis and k‐means clustering of the acquired elemental maps of Ca and Sr revealed that the newly formed bone exhibited the highest Sr fractions and that low Ca diet increased the Sr uptake by a factor of three to four. Furthermore, Sr uptake in bone of the SrCl₂‐treated animals was generally lower compared with SrR. The study clearly shows that inadequate nutritional calcium intake significantly increases uptake of Sr in serum as well as in trabecular bone matrix. This indicates that nutritional calcium intake as well as serum Ca levels are important regulators of any Sr treatment.     

动物粪便近红外光谱的应用潜力

近红外光谱技术(NIRS)以其低成本、高效、环保、无损的优势在日粮和畜产品品质分析中得到广泛应用。饲料品质参数(如粗蛋白)的获取对于日粮营养的合理搭配不可或缺,传统的近红外光谱技术将日粮的近红外光谱与日粮品质参数的化学测定值进行回归,建立预测模型对日粮品质参数进行检测。然而,在放牧条件下日粮近红外光谱的难以获取限制了这一传统建模方法在动物营养中的应用。作为动物代谢性产物,动物粪便不仅包含有日粮信息也携带有动物自身信息。近年来,基于动物粪便近红外光谱和日粮信息(日粮植物学成分、化学成分及其消化率)建立的回归模型,也已被用于动物日粮信息的检测。简要介绍F.NIRS在动物性别、品种鉴定及繁殖和寄生虫感染状态检测中的应用。NIRS在动物粪肥分析中的应用结果表明NIRS能够对粪肥中主要成分含量进行快速分析。尽管F.NIRS预测准确性有待提高,但已显示出其作为快速、有效的分析工具用于检测日粮品质参数及动物生理状态的潜力。相关的英文评述性文章业已出版,但在中国F.NIRS的研究和应用非常欠缺。期望本文的呈现有助于F.NIRS在国内的发展。推荐将NIRS作为快速分析工具用于对粪肥主要成分(DM,OM,TS,VS,TN,TKN和NH₃-N)含量进行检测。     

Biological fractionation of stable Ca isotopes in Göttingen minipigs as a physiological model for Ca homeostasis in humans

In order to investigate fractionation of calcium (Ca) isotopes in vertebrates as a diagnostic tool to detect Ca metabolism dysfunction we analyzed the Ca isotopic composition (δ^44/40Ca?=?[(⁴⁴Ca/⁴⁰Ca)_sample/(⁴⁴Ca/⁴⁰Ca)_reference]?1) of diet, faeces, blood, bones and urine from Göttingen minipigs, an animal model for human physiology. Samples of three groups were investigated: 1. control group (Con), 2. group with glucocorticosteroid induced osteoporosis (GIO) and 3. group with Ca and vitamin D deficiency induced osteomalacia (?CaD). In contrast to Con and GIO whose average δ^44/40Ca_faeces values (0.39?±?0.13‰ and 0.28?±?0.08‰, respectively) tend to be lower than their diet (0.47?±?0.02‰), δ^44/40Ca_faeces of ?CaD (?0.27?±?0.21‰) was significantly lower than their δ^44/40Ca_diet (0.37?±?0.03‰), but also lower than δ^44/40Ca_faeces of Con and GIO. We suggest that the low δ^44/40Ca_faeces of ?CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage. Assuming that this endogenous Ca source is a common physiologic feature, a fractionation during Ca absorption is also required for explaining δ^44/40Ca_faeces of Con and GIO. The δ^44/40Ca_urine of all groups are high (>2.0‰) reflecting preferential renal reabsorption of light Ca isotopes. In Göttingen minipigs we found a Ca isotope fractionation between blood and bones (Δ^44/40Ca_blood-bone) of 0.68?±?0.15‰.     

基于光腔衰荡光谱的便携式呼气异戊二烯分析仪性能评估

呼气异戊二烯是一种内源性代谢产物,其含量与人体血液中的胆固醇水平存在关联。但人体呼气影响因素众多,寻找其与胆固醇水平诊断参数的定量相关性,需要对选取的特定人群进行有效的呼吸气体分析（实时、在线、高灵敏度、高选择性、高精度的大量呼气数据获取）。光腔衰荡光谱（CRDS）是一种具有极高灵敏度、稳定性和选择性的光谱技术。采用目前市场在售的单波长紧凑型半导体紫外激光器,搭建了一套基于CRDS的呼气异戊二烯分析仪,该分析仪主要由激光系统、真空腔体、光电探测模块以及数据采集模块构成。线性拟合的结果显示所获得的衰荡信号接近单指数衰减（R2=0.998 39）,符合朗伯-比尔定律。探究了不同信号平均次数对衰荡信号稳定性的影响,综合考虑衰荡信号的稳定性和分析仪的响应时间,采用128次作为实验过程中的信号平均次数。对呼气异戊二烯分析仪的性能进行了测试,为了表征分析仪的稳定性,持续测量了分析仪16 min的真空衰荡时间。使用氮气、空气和呼吸样本,测量了呼气异戊二烯分析仪的重复性和响应速度。为了测试分析仪的线性度,测量了不同粒子数密度的异戊二烯标准气体（10×10-9,30×10-9,50×10-9,100×10-9,200×10-9）的衰荡时间。最后分析了在224 nm测量异戊二烯存在的光谱干扰问题（NO,N₂O和丙酮）。实验表明：分析仪具有高的灵敏度（检测极限为0.49×10-9）、良好的重复性、稳定性（0.48%）、近实时的响应速度（1秒测量一个数据）和良好的线性度（R2=0.993 13）,将检测极限提高至现有水平的1/1 000。研究证明基于CRDS的便携式呼气异戊二烯分析仪可实现对人体呼气异戊二烯的有效分析。     

Breath water-based doubly labelled water method for the noninvasive determination of CO2 production and energy expenditure in mice

ABSTRACT

We explored a novel doubly labelled water (DLW) method based on breath water (BW-DLW) in mice to determine whole body CO₂ production and energy expenditure noninvasively. The BW-DLW method was compared to the DLW based on blood plasma. Mice (n?=?11, 43.5?±?4.6?g body mass (BM)) were administered orally a single bolus of doubly labelled water (1.2?g H₂¹⁸O kg BM^?1 and 0.4?g ²H₂O kg BM^?1, 99 atom% (AP) ¹⁸O or ²H). To sample breath water, the mice were placed into a respiration vessel. The exhaled water vapour was condensed in a cold-trap. The isotope enrichments of breath water were compared with plasma samples. The ²H/¹H and ¹⁸O/¹⁶O isotope ratios were measured by means of isotope ratio mass spectrometry. The CO₂ production (RCO₂) was calculated from the ²H and ¹⁸O enrichments in breath water and plasma over 5 days. The isotope enrichments of breath water vs. plasma were correlated (R²?=?0.89 for ²H and 0.95 for ¹⁸O) linearly. The RCO₂ determined based on breath water and plasma was not different (113.2?±?12.7 vs. 111.4?±?11.0?mmol?d^–1), respectively. In conclusion, the novel BW-DLW method is appropriate to obtain reliable estimates of RCO₂ avoiding blood sampling.