Dietary influences on nonexercise physical activity and energy expenditure in C57BL/6J mice

It is well established that the lack of physical activity can lead to weight gain or obesity. However, there is limited information on influences of diet components on physical activity. Thus the purpose of this study was to investigate the role of major dietary components on energy expenditure by affecting nonexercise physical activity in C57BL/6J mice. All mice were assigned to 1 of the following 4 dietary groups based on their body weight and baseline physical activity; low fat/normal protein, high fat/normal protein, low fat/low protein, or low fat/high protein. After 3 mo, the highest weight gain was observed in animals fed with high-fat/normal-protein diet, and the caloric intake was significantly lower in low-fat/high-protein diet-fed mice compared to other groups. However, there were no significant changes in nonexercise physical activity during experimental periods in all groups. The respiratory quotient and energy expenditure were not significantly different among the dietary groups. These findings suggest that diet-induced obesity is not explainable by levels of physical activity and energy expenditure. PRACTICAL APPLICATION: The understanding the link between diet and nonexercise physical activity would provide important knowledge that will potentially assist appropriate food choices to control obesity and its related health problems.     

缺铁性贫血对青少年体力能力影响的研究

本文对15例缺铁性贫血和15例正常男生的有氧能力和日常体力活动状况进行研究. 根据铁营养状况进行分组,铁营养指标包括血红蛋白、血清铁蛋白、血清铁和血清转铁蛋白受体,研究两组学生的最大耗氧量、相对体重最大耗氧量、相对瘦体重最大耗氧量、最大作功时间、最大心率以及在工作(学习)和休闲时的净心率、能量消耗和有氧活动时间等指标. 结果表明,缺铁性贫血学生的最大耗氧量,相对体重最大耗氧量、相对瘦体重最大耗氧童、最大作功时间显著下降;休闲时的净心率和能量消耗较正常对照组明显降低,有氧活动时问显著少于正常对照组. 结果提示,缺铁性贫血男性青少年的有氧能力受到损伤,日常体力活动减少.     

A system to assess fitness of dairy cows responding to exercise training

Objectives were to develop a system to administer exercise training to dairy cows, to measure potential physiological indicators of fitness, and to assess physical fitness. Nonlactating, nonpregnant multiparous Holstein cows (n = 19) were in one of three exercise training treatments: no exercise; 1-h exercise; or 2-h exercise by walking 3 km/h every other day for 60 d in a mechanical walker. Treadmill tests on d 15, 30, 45, and 60 consisted of walking (5 km/h) with 1.6% increases in slope at 3-min intervals until heart rates reached 180 beats per minute (experimentally specified maximum) or until cows refused to walk. Fitness indices analyzed in tests as single datum points at maximal heart rates were length of time of test, heart rate, and plasma L-lactate concentration at end of the test, and change in heart rate and lactate concentration during the test. Exercised (1 or 2 h) cows had longer times to end of tests than nonexercised cows. Maximal and change in heart rates or plasma lactate during tests did not indicate improved physical fitness. However, when all data were evaluated as repeated measures of day and minute of tests, reductions of heart rates and plasma lactate concentrations were greatest on d 60 between exercised and nonexercised cows indicating improved fitness. Acid-base measurements were not found useful in this study. Changes of heart rates and plasma lactate concentrations over time (repeated measures) of treadmill tests quantified the physical fitness of dairy cows and can be used to compare potential responses to different exercise training treatments in this system.     

碳酸酐酶的应用研究现状及其酶活检测方法述评

碳酸酐酶（CA）是一类催化二氧化碳和水生成碳酸氢根和氢离子的可逆反应的锌酶.它广泛存在于动植物及微生物体中,且在生物加工过程中起重要作用.由于碳酸酐酶的特性,它正被广泛应用于诸如生物检测、天然活性物质的筛选、生物传感器、CO2捕集和生理诊断等领域.对碳酸酐酶的应用现状以及碳酸酐酶的酶活测定方法进行了综述.     

Exercise training of late-pregnant and nonpregnant dairy cows affects physical fitness and acid-base homeostasis

The objective was to determine if exercise training improves physical fitness of nonlactating, late-pregnant and nonpregnant multiparous Holstein cows and alters acid-base homeostasis during an exercise test on a treadmill. Twenty-six pairs (each pair having 1 late-pregnant and 1 nonpregnant) of cows were assigned to treatments of exercise training or no exercise. Exercise training was walking (1.25 to 1.5 h at 3.25 km/h) every other day in an outdoor mechanical walker for 70 d. Cows completed treadmill exercise tests on d 0, 30, and 60 of the experiment or about d 70, 40, and 10 before expected parturition of the pregnant cow of each pair. On d 0, physical fitness was similar among all cows based on durations of treadmill tests, heart rates, and acid-base measurements at given workloads (21.1 ± 0.6 min; 144 ± 2.2 beats per min; plasma lactate 3.1 ± 1.9 mmol/L; and venous blood pH 7.44 ± 0.0035, respectively). After 60 d of training, exercised cows walked longer during treadmill exercise tests compared with nonexercised cows (23.7 vs. 18.3 ± 0.85 min, respectively), indicating greater physical fitness (pooled across pregnancy status). Heart rates and plasma lactate concentrations at given workloads were less (144 vs. 156 ± 2.7 beats per min; and 1.4 vs. 3.2 ± 0.24 mmol/L for exercised compared with nonexercised cows, respectively). Additionally, exercised cows more effectively maintained acid-base homeostasis during treadmill tests compared with nonexercised cows. Metabolic, endocrine, and nutritional demands associated with late pregnancy did not affect responses differently to exercise training for late-pregnant compared with nonpregnant cows. Overall, exercise training of late-pregnant and nonpregnant cows for 60 d improved physical fitness.     

Technical note: the use of a physical activity monitor to estimate the eating time of cows in pasture

Accurate eating time can be used as an index of forage dry matter intake in grazing cows. To develop a method for easily estimating the eating time of dairy cows in a pasture, 8 lactating Holstein cows were fitted with collars equipped with commercial uniaxial accelerometers; namely, the Kenz Lifecorder EX (LCEX; Suzuken Co. Ltd., Nagoya, Japan), and were allowed to graze in a pasture for 4, 8, or 20 h daily for 7 d. The LCEX device recorded the intensity of the physical activity categorized into 1 of 11 activity levels ranging among 0 (no movement), 0.5 (subtle) and from 1 to 9 (1, light; 9, vigorous intensity) every 4 s during the experimental period. The activities of the animals were also video-recorded for 11 h and were manually classified into 7 categories (eating, searching, ruminating, standing resting, lying resting, drinking, and walking) at 4-s intervals. According to the count distribution of the activity levels for the categorized activities, 94.4% of the counts involving eating activity ranged from activity level 1 to 7. On the other hand, most of the counts were activity level 0 or 0.5 when ruminating and resting activities were observed. No records of activity level 8 or 9 were found in any activities. When activity level 1 was used as a threshold for discriminating eating from the other activities, the lowest misclassification rate of 5.5% was observed. With a threshold of activity level 1, the eating times in pasture for cows grazing for 4, 8, and 20 h/d were 142.8, 290.6, and 438.4 min/d, respectively, and the proportions of the time spent in pasture that were made up of eating time were 0.66, 0.67, and 0.38, respectively [the proportion during daytime (8 h of the 20-h grazing treatment) was 0.63 and that at nighttime (12 h of the 20-h grazing treatment) was 0.23]. The use of the LCEX device allows for easy measurement of eating time and facilitates the determination of the pattern of eating activity in pasture for grazing cows.     

酵母蛋白酶A活性检测方法的比较

利用共振光散射技术建立了一种新的蛋白酶A活性检测方法-RLS法。从标准曲线、精密度、检测限、实际样品的测定等方面,对现有的蛋白酶A活性检测方法和RLS法进行了比较。结果显示,与其他三种方法（UV法、Lowry法、Bradford法）相比,RLS法检测限低（0.662μg/mL）,线性范围宽（1⁵00μg/mL）,标准曲线的线性良好（R2=0.9974）,精密度高（RSD=1.95%）,并在实际样品的检测中具有明显优势。有效性实验证明此方法的测定结果准确可靠,与荧光底物法测定结果之间的相关性系数为0.9917。      

食品抗氧化评价体系及其选择使用

目前有许多食品抗氧化能力评价方法,但是对于特定的食品该选择何种抗氧化评价方法还不确定,为了解决这个问题,主要介绍不同抗氧化评价方法的机理及其特点,以及它们在食品抗氧化评价体系中的选择作用。从体外、体内两个方面对食品抗氧化评价特点进行具体地介绍,以达到对食品抗氧化性的全面分析。值得推荐的是从血浆脂质过氧化水平和氧化应激生物标志物对食品的抗氧化能力进行分析。     

提取方法对羊栖菜多糖理化性质及体外生物活性的影响

目的 探究不同提取方法对羊栖菜多糖理化性质与体外生物活性的影响。方法 以羊栖菜(Sargassum fusiforme)为研究对象,采用热水提取法(hot water extraction,HWE)、碳酸钠提取法(alkaline-assisted extraction,ALAE)、氯化钙提取法(calcium chloride-assisted extraction,CAAE)及微波辅助水提法(microwave-assisted water extraction,MAE)和超声辅助水提法(ultrasound-assisted water extraction,UAE)共5种方法提取羊栖菜多糖,分析不同提取方法对多糖的提取效果、理化性质、体外抗氧化和降血糖活性的影响。结果 以水为溶剂进行提取,多糖得率相对较高,且微波和超声辅助可显著增强提取效果。ALAE提取的羊栖菜多糖分子量最低(924.96 k Da)且热稳定性最好(T_max=255.84℃)。不同方法提取所得多糖的单糖组成类似,均主要由甘露糖、氨基葡萄糖、葡萄糖、阿拉伯糖、鼠李糖、半乳糖、半乳糖醛酸和岩藻...     

A review on flow characterization methods for cereal grain‐based powders

Flow difficulties during handling, storage, and processing are common in cereal grain‐based powder industries. The many studies that focus on the flow properties of powders can be classified as flow indicators, shear properties, and dynamic flow properties. The non‐uniformity of physical and chemical characteristics of the individual particles that make up the bulk solid of cereal grain‐based powders adds complexity to the characterization of flow behavior. Even so, knowledge of flow behavior is critical to the design of productive and cost‐effective equipment for handling and processing of these powders. Because many factors influence flow, a single property/index value may not satisfactorily quantify the flow or no‐flow of powders. For powders of biological origin, chemical composition and environmental factors such as temperature and relative humidity complicate flow characterization. This review focuses on the specific flow characteristics that directly affect powder flow during handling, processing, and storage. © 2015 Society of Chemical Industry     

Effect of prepartum exercise,pasture turnout,or total confinement on hoof health

Lameness is a major welfare concern in the dairy industry, and access to physical activity during the dry period may improve hoof health. The objective of this study was to determine the effects of forced exercise, pasture turnout, or total confinement of dry cows on horn growth and wear and sole thickness. Twenty-nine primiparous and 31 multiparous, pregnant, nonlactating Holstein (n = 58) and Jersey-Holstein crossbred (n = 2) dairy cows were assigned to either total confinement (n = 20), exercise (n = 20), or pasture (n = 20) treatments at dry-off using rolling enrollment from January to November 2015. Cows were managed with a 60-d dry period (58.5 ± 5.4 d) divided into far-off (dry-off to 2 wk before parturition) and close-up periods (2 wk before projected parturition). Cows were housed in a naturally ventilated, 4-row freestall barn at the University of Tennessee's Little River Animal and Environmental Unit (Walland, TN) with concrete flooring and deep-bedded sand freestalls. Cows assigned to confinement remained in the housing pen. Exercise cows were walked for a targeted 1.5 h at 3.25 km/h, 5 times/wk until calving. Pasture cows were turned out for a targeted 1.5 h, 5 times/wk until calving. Hoof growth and wear and sole thickness of the rear hooves were measured on d 2 and 44, relative to dry-off. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Cranial and caudal horn wear was greater for exercise cows than confinement and pasture cows. Exercise cows experienced more equal rates of horn growth and wear cranially. Confined cows tended to increase sole thickness from d 2 to 44, relative to dry-off. Frequent, short duration exercise on concrete did not impair the hoof health of late-gestation dry cows. Further, exercise may improve overall hoof health, potentially improving cow welfare.     

Food-derived peptidic antioxidants: A review of their production, assessment, and potential applications

Antioxidant properties of food-derived peptides have been described in an increasing number of studies in recent years. Consequently, these peptides are being considered as potential sources to control various oxidative processes in the human body as well as in food. It is however difficult to compare results from various studies due to the diversity of in vitro assay systems and inconsistency in the conditions used to evaluate antioxidative capacity of peptides and protein hydrolysates. Further, specific assays and biomarkers are yet to be established to confirm their bioactive potential. This review summarizes the literature on food sources and methods of antioxidative peptide production, and the reported efficacies and mechanisms of their action. Furthermore, it presents a critical evaluation of methods used for assessing antioxidative activity of peptides. Examples of promising applications of these peptides in food, nutraceuticals and cosmeceuticals are also discussed with an insight to the future research needs.     

Evaluation of sample preparation methods for water activity determination in jerky and kippered beef: A research note

Commercially available packaged whole muscle beef jerky, chopped and formed beef jerky, and kippered beef steak were obtained from retail stores to determine the effect of two sample preparation methods on water activity (a_w). Intact samples were prepared by cutting product into a hexagonal shape with a 3.2 cm diameter. Diced samples were prepared by cutting the product into 0.4 × 0.4 cm squares. Whole muscle jerky a_w was higher (0.016 units; P < 0.001) using the intact method compared to the diced method. There was no difference (P > 0.05) in a_w levels between the two preparation methods for chopped and formed jerky or kippered beef steak. An intact sample preparation method is recommended for a_w determination of whole muscle jerky to obtain a more conservative value, especially if a_w is near the margin of safety.     

A novel chemoenzymatic synthesis of phytosteryl caffeates and assessment of their antioxidant activity

Phytosterols and their derivatives are relevant in food, pharmaceuticals, and cosmetics. In addition to their well-known effect in lowering low-density lipoprotein (LDL) cholesterol, they also possess other biological activities, such as anti-inflammatory, anti-atherogenicity, and anti-carcinogenic potential. A novel method was developed for chemoenzymatic synthesis of phytosteryl caffeates through an intermediate vinyl caffeate, which was first chemically produced and subsequently esterified with phytosterols through lipase-assisted alcoholysis. The structures of the phytosteryl caffeates were confirmed by infrared (IR) and high performance liquid chromatography–mass spectrometry/mass spectrometry (HPLC–MS/MS). The ORAC values of phytosteryl caffeates were two times higher than that of caffeic acid. In a meat model system, the antioxidant activity of phytosteryl caffeates was higher than caffeic acid and vinyl caffeate, and that of butylated hydroxyanisole (BHA), a commonly used synthetic antioxidant. The results indicate that phytosteryl caffeates have a good potential for use as food antioxidants.     

广州市在校高职大学生饮食行为与身体活动调查分析

目的:了解广州市在校高职院校大学生饮食行为与身体活动现状。方法:以广州市某职业学院1 310名学生为调查对象,采用随机抽样的方法进行问卷调查。结果:有52.67%的学生不会每天吃早餐,仅有7.63%每天喝奶类,每天吃新鲜蔬菜和水果的分别为56.49%和16.79%,有45.8%的学生有偏食的倾向;只有16.03%的学生能经常参加体育锻炼。结论:高职学生存在较多健康危险行为,仍需有效的健康教育。     

海南省黎族、苗族13—15岁中学生体质状况对比研究

随机抽取海南民族地区841名13—15岁中学生为研究对象,对其身体形态、身体机能、运动能力进行专门测试。通过黎族、苗族及与全国数据的对比分析,了解和掌握黎、苗两族中学生的体质状况。结果表明,黎族、苗族13—15岁中学男、女生体质各指标普遍高于全国平均水平,黎族、苗族中学生间体质现状具有较大差异。     

Physical and chemical methods used to enhance the structure and mechanical properties of protein films: A review

Efforts for developing protein films as biodegradable packaging materials have increased in recent years. One of the drawbacks of such films is that their functional properties are generally inferior to those of synthetic films. Although protein films typically have excellent gas barrier properties, they tend to have higher water vapor permeability, are mechanically weaker, and have lower elongation as compared to most synthetic polymers. This paper will review the various methods that have been reported to enhance the physical and barrier properties of protein films. The effects of film formulation and preparation conditions, including plasticization, pH alteration, and lipid addition, on the functional properties of protein films are discussed. The paper also offers a comprehensive review of the various methods used to modify protein film functional properties, including cross-linking techniques induced by heat, chemical, enzymes, and irradiation, and use of nanocomposites to enhance their barrier properties. A critical comparison of the different technical solutions is offered, and the challenges and potential applications of these films are discussed.     

Physical and chemical modification of starches: A review

The development of green material in the last decade has been increased, which tends to reduce the impact of humans on the environment. Starch as an agro-sourced polymer has become very popular recently due to its characteristics, such as wide availability, low cost, and total compostability without toxic residues. Starch is the most abundant organic compound found in nature after cellulose. Starches are inherently unsuitable for most applications and, therefore, must be modified physically and/or chemically to enhance their positive attributes and/or to minimize their defects. Modification of starches is generally carried out by using physical methods that are simple and inexpensive due to the absence of chemical agents. However, chemical modification involves the exploitation of hydroxyl group present in the starches that brings about the desired results for the utilization of starches for specific applications. All these techniques have the tendency to produce starches with altered physicochemical properties and modified structural attributes for various food and nonfood applications. This paper reviews the recent knowledge and developments using physical modification methods, some chemical modification methods, and a combination of both to produce a novel molecule with substantial applications, in food industry along with future perspectives.     

海藻酸钠寡糖的生物活性及其衍生产物研究进展

海藻酸钠寡糖是海藻酸钠经过一定的降解方式得到的低分子聚合物,其具有分子量低、水溶性强,易吸收等特性,同时还具备抗氧化、降血压、降血脂等生物活性。采用合理的方法对海藻酸钠寡糖进行修饰,得到的衍生物的生物活性、生理功能都有一定提高,可在一定程度上拓展海藻酸钠寡糖产品在食品工业、医学等领域的应用。因此,本文着重对海藻酸钠寡糖的生物活性及其衍生物的研究现状进行归纳,以期为从事海藻酸钠寡糖的研究者提供一定的参考价值。