Longitudinal changes in body weight of breastfeeding mothers in the first year after delivery and its relationship with human milk composition:a combined longitudinal and cross-sectional cohort study

Objective:Postpartum weight retention(PPWR)is a common problem among women after childbirth.The main objectives of this study are to understand the changes in body weight of breastfeeding mothers during long-term follow-up and preliminarily explore the relationship between maternal body weight and human milk composition,including macronutrients,leptin,and adiponectin.Methods:The study included a longitudinal cohort(122 mothers),and a cross-sectional cohort(37 mothers).The human milk,maternal weight,and dietary surveys were collected in the longitudinal cohort at different follow-up time points(1-14 days postpartum,2-4 months postpartum,5-7 months postpartum,and 12-17 months postpartum).The maternal body weight was analyzed using the responses in the survey questionnaires.A milk analyzer based on the mid-infrared spectroscopy(MIRS)was used to determine milk composition,and nutrition analysis software evaluated dietary intakes.In the cross-sectional cohort,participating mothers were asked to provide blood and human milk samples and pertinent information related to maternal body composition.Maternal body composition was measured by bioelectrical impedance analysis(BIA),while ELISA analyzed leptin and adiponectin in milk and serum.Results:At 5-7 months postpartum,the PPWR of breastfeeding mothers was(2.46±3.59)kg.At 12-17 months postpartum,the PPWR was(0.98±4.06)kg.PPWR was found to be negatively correlated with milk fat content within 14 days postpartum and positively correlated at 2-4 months postpartum.In addition,the maternal weight and body muscle mass were positively correlated with leptin and adiponectin in milk.Plasma leptin was positively correlated with the mother’s body weight,body mass index(BMI),FAT percentage,and body fat mass,while plasma adiponectin did not correlate with any parameter.The results also indicate that the PPWR did not correlate with leptin and adiponectin in plasma or milk.Conclusions:Breastfeeding mothers may retain considerable weight gain one year after delivery.Human milk composition may be related to changes in maternal body weight.Leptin and adiponectin in breast milk and leptin in plasma are associated with the maternal body composition.This study supports the notion that maternal nutritional status may affect offspring health through lactation,and future research should focus on exploring weight management of postpartum mothers.

Exploring hematopoietic stem cell population in human milk and its benefits for infants:A scoping review

Objective:To comprehensively explore hematopoietic stem cells(HSCs)in human milk,understanding their molecular markers,isolation methods,benefits for infants,and potential medical applications.Methods:We conducted a scoping literature review following the PRISMA-ScR guidelines.This review included studies investigating HSCs in human milk,utilizing molecular markers such as CD34^(+),CD113^(+),and CD117^(+)for characterization.Both in vitro and in vivo studies exploring the morphology,function,and clinical implications of these cells were considered.The diverse range of papers reviewed were indexed in PubMed,Science Direct,Scopus,Sage Journals,and Google Scholar,published between 2010 and 2023.Results:This scoping review explored 577 articles and selected 13 studies based on our inclusion criteria,focusing on HSCs in human milk.Most studies dilute samples prior to HSC isolation,followed by detection using markers such as CD34^(+),CD113^(+),and CD117^(+),with flow cytometry serving as the primary analysis tool,focusing on their isolation and detection methods.While no definitive benefits have been conclusively established,there is a strong belief in the potential of HSCs to positively impact infant immunity,growth,and tissue repair.Conclusions:This review presents significant evidence supporting the presence of HSCs in human milk,identified by markers such as CD34^(+),CD113^(+),and CD117^(+).These cells show considerable potential in enhancing infant health,including immunity,tissue repair,cognitive development,and gastrointestinal health.Despite methodological variations in isolation and detection techniques,the collective findings underscore the potential clinical relevance of HSCs in human milk.Moreover,this review highlights the noninvasive accessibility of human milk as a source of HSCs and emphasizes the need for further research to unlock their therapeutic potential.

The levels of osteopontin in human milk of Chinese mothers and its associations with maternal body composition

Objective:This study explored the content and change trend of osteopontin(OPN)in breast milk and analyzed the relationship between OPN in breast milk and maternal body composition.Methods:Breast-feeding mothers were recruited in Xinhua Hospital to collect breast milk and provide pertinent information.The content of OPN in breast milk was determined by enzyme-linked immunosorbent assay(ELISA).Determination of protein content in human milk was performed via the BCA method.The maternal body composition was determined by the bioelectrical impedance method.Serum glucocorticoid receptorα,adiponectin,insulin,and leptin were determined by ELISA.SPSS 25 was used for statistical analysis.Results:In the longitudinal cohort,106 mothers provided 318 milk samples at different lactation periods.The results indicate that the OPN showed dynamic changes.OPN levels were(343.2±163.5)mg/L during 1-14 days postpartum,(228.4±121.5)mg/L during 2-4 months postpartum,and(204.8±100.6)mg/L during 5-7 months postpartum.The content of OPN was very high in the first 1-14 days postpartum and then decreased.Compared with early postpartum milk,the OPN content of mature milk showed a significant relationship with maternal weight-related parameters.Additional body composition analysis was performed in 88 women at the mature milk phase.The results show that the OPN in milk is related to the mother’s body composition,especially the content of skeletal muscle mass,but not to relevant humoral factors.Conclusions:The levels of OPN in human milk of Chinese mothers showed dynamic changes with the extension of lactation time.The OPN in human milk was related to the mother’s body composition but not related to related humoral factors.

The Impact of the Block Freeze Concentration Process on Human Milk Properties Intended for Feeding Newborns

Human milk is the ideal nutritional support for premature neonates. Considering the need for aggregating nutritional value to human milk provided to such vulnerable group of infants, human milk was concentrated by the block freeze concentration technique. The effects of freeze concentration on the physicochemical properties, the efficiency of the process, color parameters, and the density and dynamic viscosity of human milk were assessed. The freeze concentration technology was used to successfully concentrate human milk to a factor equal to 180.48% and 72% of total solid retention in the second stage of freeze concentration. The values observed in the concentrates for the biochemical properties showed that the fraction of concentrated fluid human milk of the second stage (C2) presented elevated amounts of carbohydrates, protein and energy. The elevated caloric value observed in the ice fraction of the first stage (I1) refers to the retention of lipids in it. When added to human milk, C2 and I1 may satisfy the special requisites of nutrients and energy to guarantee the growth and development of preterm neonates.

Application of UPLC-MS/MS Method for Analyzing B-vitamins in Human Milk

Objective To determine ten B-vitamins in human milk by ultra-high performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. Methods The pretreated human milk samples were adequately separated and quantified within 11 min by UPLC-MS/MS with an Acquity UPLC HSS T3 column （2.1×100 mm, 1.8 μm）. The mobile phase was a gradient of 2.5 mmol/L ammonium formate aqueous solution and acetonitrile at a flow rate of 0.35 mL/min. Stable isotope internal standards were used in the analysis, to correct for the method variability, including matrix and ionization effects. The homogenized human milk samples were deproteinzed using methanol, unknown contaminants were extracted with diethyl ether and hydrophobic phase was discarded. The analytes were monitored via ESl＋ionization and detected in multiple reaction monitoring （MRM） with three acquisition functions. Results Calibration curves ranged from 0.5-160 ng/mL （thiamin, riboflavin, biotin, nicotinic acid, pyridoxine, pyridoxamine, pyridoxal）, and 2.5-800 ng/mL （pantothenic acid, FAD and nicotinamide） （R^2=0.990-0.999）. The relative recovery ranged from 80.1% to 120.2%; accuracy was determined to be 98.3% to 108.0%. Intra-day and inter-day variation were 3.4%-19.9% and 5.9%-18.1%, respectively. The limit of quantification （LOQ） for all vitamins was between 0.25 and 3 lag/L. Conclusion This method was successfully applied for simultaneous analysis of ten B-vitamins in human milk.

Individual and Combined Effects of Nucleotides and Human Milk Oligosaccharides on Proliferation, Apoptosis and Necrosis in a Human Fetal Intestinal Cell Line

Nucleotides (NT) and human milk oligosaccharides (HMO) individually affect epithelial cell growth, but their combined effects had not been studied. Herein, the impact of NT and HMO on cell proliferation, apoptosis, necrosis and cell cycle in the fetal epithelial cell line (FHs-74 Int) was determined. Cells were incubated with media containing 2.5% FBS and no epidermal growth factor (Control);fucosyllactose (FL) mix [85% 2’FL/15% 3’FL], sialyllactose (SL) mix [40% 6’SL/10% 3’SL/50% sialic acid (SA)] or LNnT at 125, 250, 500 or 1000 μg/mL with and without 250 μg/mL NT (43% CMP, 18.5% UMP, 16.4% AMP, and 22.0% GMP) for 24 or 72 h. NT alone significantly increased proliferation, but did not affect cell cycle or apoptosis/necrosis. All HMO treatments at 1000 μg/mL significantly decreased proliferation and some were also inhibitory at 250 or 500 μg/mL. When NT and HMO were simultaneously added, NT ameliorated the anti-proliferative effect of HMO. FL significantly increased cells in S phase and SL and LNnT treatments significantly increased cells in G2/M and S phases, which concomitantly decreased cells in G0/G1. HMO with NT significantly decreased the percent of cells in the G2/M phase compared to HMO alone. Higher HMO doses significantly increased the percentage of apoptotic and necrotic cells compared to control. In conclusion, HMO reduced cell proliferation and this effect is partially ameliorated by NT. It appears that HMO initially induced apoptosis/necrosis, which was later evidenced by G2/M cell cycle arrest and decreased proliferation.

Effect of human milk and colostrum on Entamoeba histolytica

AIM:Many defense factors of the mother's colostrum or milk protect infants from intestinal, respiratory and systemic infections. In the present study, we investigated the effect of colostrum and mature human milk on E. histolytica parasites in vitro.METHODS:Samples of human milk were collected from 5 healthy lactating mothers.The medium with human milk at concentrations of 2%, 5% and 10% was obtained.RESULTS:The lethal effect of E. histolytica on the medium supplemented with different concentrations of both colostrum and mature human milk was significant during the first 30min. We also detected that the results of colostrum and mature human milk were similar. No statistically significant differences were found between same concentrations of colostrum and mature human milk at the same times.CONCLUSION:Colostrum and mature human milk have significant lethal effect on E. histolytica and protect against its infection in breast fed children.

Biological and Nutritional Aspects of Human Milk in Feeding of Preterm Infants

Breastfeeding and human milk are the normative standards for feeding and nutrition of both term and pre-term infants. Fresh mother’s own milk is recognized as the optimal choice for feeding all newborns, including preterm and very low birth weight infants. Evidence documents short and long-term metabolic, immunologic and neurodevelopmental advantages of breastfeeding when compared to formula. Moreover, benefits of breastfeeding on psychological and relational aspects have to be considered. Currently, human milk supplementation is usually performed to meet the specific nutritional requirements of preterm infants. When mother’s milk is unavailable or in short supply, donor milk represents the best alternative, although some nutritional elements are inactivated by the necessary pasteurization process. Aim of this review is to briefly summarize the main biological and nutritional factors that contribute to the beneficial effects of human milk feeding for preterm infants.

Comparative Analysis of Hydrolytic Amino Acids in Human and Cow Milk of Different Lactation Periods

In this study,the hydrolytic amino acids of Chinese human and Holstein cow milk of different lactation periods were analyzed by the advanced isobaric tags for relative and absolute quantitation(iTRAQ)combined with the high performance liquid chromatography-mass spectrometry(HPLC-MS/MS)approach.The total contents of the hydrolytic amino acids in cow colostrum,cow mature milk,human colostrum and human mature milk were 5.00,4.38,2.12 and 2.48 g·L^(-1),respectively.Among these,the contents of the hydrolytic amino acids in cow milk were higher than those in human milk,indicating a decreasing trend with the prolongation of lactation.Additionally,principal component and hierarchical cluster analyses were used to further screen the differentially expressed amino acids.These results enhanced the understanding of the hydrolytic amino acids in cow and human milk across different lactation periods,which could provide potential directions for newborn dairy powder and nutritious supplementary.

Gut microbiota in preterm infants receiving breast milk or mixed feeding

BACKGROUND Preterm birth is the leading cause of mortality in newborns,with very-low-birthweight infants usually experiencing several complications.Breast milk is considered the gold standard of nutrition,especially for preterm infants with delayed gut colonization,because it contains beneficial microorganisms,such as Lactobacilli and Bifidobacteria.AIM To analyze the gut microbiota of breastfed preterm infants with a birth weight of 1500 g or less.METHODS An observational study was performed on preterm infants with up to 36.6 wk of gestation and a birth weight of 1500 g or less,born at the University Hospital Dr.JoséEleuterio González at Monterrey,Mexico.A total of 40 preterm neonates were classified into breast milk feeding(BM)and mixed feeding(MF)groups(21 in the BM group and 19 in the MF group),from October 2017 to June 2019.Fecal samples were collected before they were introduced to any feeding type.After full enteral feeding was achieved,the composition of the gut microbiota was analyzed using 16S rRNA gene sequencing.Numerical variables were compared using Student’s t-test or using the Mann–Whitney U test for nonparametric variables.Dominance,evenness,equitability,Margalef’s index,Fisher’s alpha,Chao-1 index,and Shannon’s diversity index were also calculated.RESULTS No significant differences were observed at the genus level between the groups.Class comparison indicated higher counts of Alphaproteobacteria and Betaproteobacteria in the initial compared to the final sample of the BM group(P<0.011).In addition,higher counts of Gammaproteobacteria were detected in the final than in the initial sample(P=0.040).According to the Margalef index,Fisher’s alpha,and Chao-1 index,a decrease in species richness from the initial to the final sample,regardless of the feeding type,was observed(P<0.050).The four predominant phyla were Bacteroidetes,Actinobacteria,Firmicutes,and Proteobacteria,with Proteobacteria being the most abundant.However,no significant differences were observed between the initial and final samples at the phylum level.CONCLUSION Breastfeeding is associated with a decrease in Alphaproteobacteria and Betaproteobacteria and an increase of Gammaproteobacteria,contributing to the literature of the gut microbiota structure of very low-birth-weight,preterm.

Lipase-Catalyzed Synthesis of Sn-2 Palmitate: A Review

Human milk fat(HMF)is an important source of nutrients and energy for infants.Triacylglycerols(TAGs)account for about 98%of HMF and have a unique molecular structure.HMF is highly enriched in palmitic acid(PA)at the sn-2 position of the glycerol backbone(more than 70%)and in unsaturated fatty acids at the sn-1,3 position.The specific TAG structure in HMF plays a valuable function in infant growth.Sn-2 palmitate(mainly 1,3-dioleoyl-2-palmitoyl-glycerol)is one of the structured TAGs that is commonly supplemented into infant formula in order to enable it to present a similar structure to HMF.In this review,the development of the lipase-catalyzed synthesis of sn-2 palmitate over the last 25 years are summarized,with a focus on reaction schemes in a laboratory setting.Particular attention is also paid to the commercialized sn-1,3 regioselective lipases that are used in structured TAGs synthesis,to general methods of TAG analysis,and to successfully developed sn-2 palmitate products on the market.Prospects for the lipase-catalyzed synthesis of sn-2 palmitate are discussed.

Human Milk Oligosaccharides Enhance Innate Immunity to Respiratory Syncytial Virus and Influenza <i>in Vitro</i>

Human milk oligosaccharides (HMO) contribute to innate immunity by enhancing growth of beneficial bacteria, epithelial cell maturation and mucosal barrier integrity. They have immunomodulatory effects and can block pathogen binding to host cell surface glycans or receptors. We investigated the effects of 2’-fucosyllactose (2’FL), 6’-sialyllactose (6’SL), 3’-sialyllactose (3’SL) and lacto-N-neoTetraose (LNnT) on human respiratory epithelial cell lines or peripheral blood mononuclear cells (PBMCs) following respiratory viral infectionin vitro. Expression of cytokines and viral load were monitored in infected cells. These biomarkers of innate immunity were selected since viral load and cytokine levels (IP-10, MIP-1α, IL-6, IL-8, TNF-α) have been correlated with disease severity in respiratory syncytial virus (RSV) and influenza (IAV) virus infectionin vivo. 2’FL significantly decreased RSV viral load and cytokines associated with disease severity (IL-6, IL-8, MIP-1α) and inflammation (TNF-α, MCP-1) in airway epithelial cells. LNnT and 6’SL significantly decreased IAV viral load in airway epithelial cells. 6’SL dose-dependently down-regulated IP-10 and TNF-α in RSV infected PBMCs. HMO at or below levels found in breast milk enhance innate immunity to respiratory viruses in vitro and may interact directly with cells to modulate biomarkers of innate immunity.

Gastrointestinal Tract Development in Unweaned Calves Feeding Different Amounts of Milk and Different Starters

This study was conducted to determine the effect of different starter diets and different amounts of milk on growth performance and gastrointestinal tract development in unweaned calves. 16 calves were assigned to 4 groups, 4 calves in each group. These four groups received the following treatments respectively: 1) high milk (6 L) + low starch (21%), high NDF (28%), high molasses (10%) starter (HMLS group);2) high milk (6L) + high starch (40%), low NDF (14%), low molasses (5%) starter (HMHS group);3) low milk (3 L) + low starch (21%), high NDF (28%), high molasses (10%) starter (LMLS group);4) low milk (3 L) + high starch (40%), low NDF (14%), low molasses (5%) starter (LMHS group). The trial was of 2 × 2 factorial design. All calves had free access to hay and water. Results showed that the low milk allowance increased calf concentrate dry matter intake (DMI) and total DMI, reduced body height at 4 weeks of age, reduced heart girth at 6 weeks of age (P < 0.05). The low milk allowance increased complex stomach full weight, reticulorumen full weight, and the percentages of stomach full weight and reticulorumen full weight over body weight (P < 0.05). The low starch, high fiber, high molasses starters reduced the complex stomach full weight, the proportion of the complex stomach empty weight over body weight, reticulorumen empty weight, abomasum full weight, the proportion of abomasum empty weight over body weight and reticulorumen volume (P < 0.05). The low milk allowance increased calf intestine length, small intestine full weight, the proportion of small intestine full weight over body weight, but reduced the jejunum villus width (P < 0.05), increased ruminal pH (P < 0.05). The low milk allowance reduced papilla length in rumen anterior ventral blind sac, but increased papilla length in the posterior ventral sac

Assay of ghrelin concentration in infant formulas and breast milk

AIM: To test if total ghrelin is present in infant formulas. METHODS: Using a radioimmunoassay, we measured total ghrelin concentrations in 19 samples of commercial infant formulas and in 20 samples of human milk. We also determined ghrelin concentration in the serum of infants and lactating mothers. RESULTS: Ghrelin concentrations were significantly higher in artificial milk (2007.1 ± 1725.36 pg/mL) than in human milk (828.17 ± 323.32 pg/mL) (P = 0.005). The mean ghrelin concentration in infant serum (n = 56) was 1115.86 ± 42.89 pg/mL, and was significantly higher (P = 0.023) in formula-fed infants (1247.93 ± 328.07 pg/mL) than in breast-fed infants (1045.7 ± 263.38 pg/mL). The mean serum ghrelin concentration (mean ± SD) in lactating mothers (n = 20) was 1319.18 ± 140.18 pg/mL. CONCLUSION: This study provides evidence that total ghrelin is present in infant formulas. This findingraises diverse questions regarding the uptake, absorption and metabolic effects of this hormone.

基于UPLC/Q-TOF-MS技术分析人乳中VD及其酯类分布规律

利用超高效液相色谱/四极杆飞行时间质谱检测技术对来自不同泌乳阶段(初乳0~7 d、过渡乳8~15 d、成熟乳16 d以后)的108份人乳样品进行VD和VD酯的组成和含量分析。结果表明,人乳中含有4种VD及20种VD酯,其中初乳中含有16种VD酯,过渡乳中含有18种VD酯,成熟乳中含有14种VD酯。在整个泌乳阶段中,初乳中VD_(2)和25-羟维生素D_(3)的平均含量最高,分别为26.83 ng/L和160.67 ng/L;过渡乳中VD3的平均含量最高,为119.87 ng/L;成熟乳中1,25-二羟维生素D_(3)的平均含量最高,为1.82 ng/L。初乳、过渡乳和成熟乳中VD酯平均含量分别为11.89、10.73 ng/L和11.47 ng/L,其中十四碳烯酸维生素D_(2)酯(C_(14:1))的含量在整个泌乳阶段中最高。通过偏最小二乘法判别分析表明,初乳、过渡乳和成熟乳能够被较好分开,说明人乳VD及VD酯从初乳到成熟乳发生了种类和含量上的变化。不同VD酯之间表现出一定的相关性。研究结果能为婴儿配方食品的开发提供数据支持。

Identification and characterization of resistance and pathogenicity of Enterococcus spp.in samples of donor breast milk

BACKGROUND Breast milk is the primary source of nutrition for newborns.Hospitalized babies frequently need nutritional support from Human Milk Banks.As bacterial species of the genus Enterococcus are part of the microbiota of healthy donors,they may contaminate samples of pumped breast milk.AIM To identify and characterize the bacterial virulence and resistance in samples isolated from the nipple-areolar region,hands,and breast milk aliquots from donors at the Human Milk Bank of Municipal Hospital EsauMatos in the city of Vitória da Conquista,Bahia State,Brazil.METHODS The personal hygiene and sanitation of donors were analyzed with the aim of identifying possible reasons for contamination of pumped milk.Cutaneous samples as well as aliquots of unpasteurized and pasteurized milk from 30 participants were obtained.Each Enterococcus spp.isolate underwent a disk diffusion susceptibility test and molecular biology techniques to determine resistance and virulence genes.RESULTS Enterococcus spp.were identified in 30%of donors(n=9),and 11 specimens were isolated.Resistance to tetracycline was highly prevalent,being detectable in 63%of the isolates(n=7)and followed by intermediate sensitivity to ciprofloxacin,observed in 27%of the specimens(n=3).The efaA gene was found in 63%(n=7)of the isolates,while the ace gene was detected in 27%(n=3).CONCLUSION This study illustrates the importance of microbiological monitoring by Human Milk Banks and the need for alternatives to prevent the presence of Enterococcus spp.in hospital settings.

Breast Milk Micronutrients in Lactating Mothers from Ribeirao Preto(SP),Brazil

Breast milk is the ideal food for infants and should be consumed as the exclusive food for the first six months and then be complemented up to two years of age. The aim of this study is to determine breast milk’s content of macro and micronutrient in lactating mothers from the Ribeir?o Preto (SP) region, in Brazil. A cross-sectional study was conducted with breast milk samples of 70 mothers from the city of Ribeir?o Preto (SP). The samples were analyzed in order to determine iron, copper, zinc, calcium and magnesium concentrations. They were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The study was approved by the Research Ethics Committee of the University Hospital, Faculty of Medicine of Ribeir?o Preto, University of S?o Paulo, and all subjects gave written informed consent to participate. The current study revealed that all 70 lactating mothers were healthy and delivered babies more than 38 weeks gestation;71.4% of them were younger than 30 years and 47.1% were primiparae. The iron, copper, zinc, calcium and magnesium concentrations detected in milk were 2.7 ± 0.4, 0.4 ± 0.02, 3.6 ± 0.2, 142 ± 21.6 and 39.8 ± 4.2 mg/L, respectively. Therefore, it can be concluded that in the present sample, except for calcium, all other mineral concentrations were adequate for the infant’s requirements according to the Dietary Reference Intake (DRI).

The Protection of the “Third Kind of Workers” in Gig Economy from the Perspective of Social Rights

Due to the new flexible employment mode of the gig economy,many workers in the gig economy cannot be classified according to the traditional dualistic division of labor relations and non-labor relations,and their rights are basically under no protection.As human beings making a living through their labor,the workers in the gig economy should be entitled to basic human rights,among which the most directly related is social rights.The concept and theoretical framework of"independent workers"put forward by American scholars is more conducive to the protection of their social rights.This theory not only has the legal basis of international law,but also conforms to the legislative purpose of striking a balance between the protection of workers and the sustainable development of the gig economy.It is also practical.Based on this theory,China’s national conditions,and the core conventions of the International Labour Organization,we propose a new way to protect"the third kind of workers"in the gig economy.

Metadata Analysis of Persistent Organic Pollutants in National Pools of Human Milk in Support of the Stockholm Convention Implementation

A set of human milk samples,consisting of pools from up to 50 mothers that delivered their first baby was assessed for the persistent organic pollutants(POPs)listed in the Stockholm Convention.It must be noted that only samples that qualified for the criteria,as established in the global monitoring plan of the Stockholm Convention,following an initial protocol from the World Health Organization,were included.The data do not allow for an assessment of POP concentrations in breast milk with lactation period nor,in most cases and when not indicated otherwise,a comparison within the same country.The assessment does not rank the POPs as to the risk for breastfeeding.Rather the measurements provide a basis for countries to compare among POPs or with other countries.A regional preference for certain POPs could not be identified;thus,taking into account global food supply chains and local production elsewhere does not allow us to prioritize a country for a certain POP.Although the highest concentrations were always found for the sum of DDT,these samples were not prominent in multivariate statistical analyses.The best indicator for the scale of POPs in breast milk was the sampling year:the earlier a national pool was created,the higher and the wider spread were the concentrations:see the example of dioxin-like POPs and indicator PCB.For some POPs,the income of a country seems to indicate scale and POP compounds.The population density was not found to be a suitable predictor or discriminator.Since all POPs seemed to level off and some POPs were only measured after the entry-into-force of the Stockholm Convention in 2004,we do not have a strong indicator to determine POP concentrations in the 1980s or before.

Lipozyme RM IM在人乳替代脂合成中的循环利用及结构变化

目的:研究Lipozyme RM IM在人乳替代脂合成中的应用及其在循环利用中结构的变化。方法:以sn-2高棕榈酸甘油三酯和游离脂肪酸为底物,在Lipozyme RM IM催化下同步合成主要成分为1,3-二油酸-2-棕榈酸甘油三酯(1,3-dioleoyl-2-palmitoylglycerol,OPO)和1-油酸-2-棕榈酸-3-亚油酸甘油三酯(1-dioleoyl-2-palmitoyl-3-linoleoylglycerol,OPL)的人乳替代脂,考察合成过程中OPO与OPL含量、油酸与亚油酸含量、总棕榈酸含量、sn-2棕榈酸含量、酶活力、脂肪酶二级结构信息和内源荧光强度等指标,研究LipozymeRMIM在合成人乳替代脂中的应用及其循环利用特性。结果:以中国母乳脂质数据库为依据评判所合成人乳替代脂指标,Lipozyme RM IM循环使用第1次时,人乳替代脂中OPO相对含量为19.41%,OPL相对含量为17.04%,总脂肪酸中油酸相对含量为35.63%,亚油酸相对含量为22.30%,总棕榈酸相对含量为28.80%,sn-2棕榈酸相对含量为52.40%;当Lipozyme RM IM循环使用至第17次时,母乳结构脂中OPO相对含量为8.50%,OPL相对含量为7.62%,总脂肪酸中油酸相对含量为28.62%,亚油酸相对含量为13.38%,总棕榈酸相对含量为38.26%,sn-2棕榈酸相对含量为58.40%,均与中国母乳脂质范围一致。但Lipozyme RM IM循环使用超过17次后,酶法合成产物脂质组成与中国母乳脂质范围相差甚远。结论:Lipozyme RM IM作为一种酯交换能力优异的脂肪酶,在合成人乳替代脂的过程中可以累计使用17次,证明了固定化脂肪酶在合成人乳替代脂中有较好的循环使用特性。该研究为脂肪酶在人乳替代脂合成中的广泛应用提供了参考依据,同时也为连续性反应器合成人乳替代脂过程中脂肪酶的循环利用提供了参考。