Amino acids

氨基酸
  • 文章类型: Journal Article
    研究序列及其相应的三维结构之间的关系有助于结构生物学家解决蛋白质折叠问题。尽管有几种实验和计算机模拟方法,仍然从序列中理解或解码三维结构仍然是一个谜。在这种情况下,结构预测的准确性起着不可或缺的作用。为了解决这个问题,已创建更新的Web服务器(CSSP-2.0),以通过部署现有算法来提高我们以前版本的CSSP的准确性。它使用输入作为概率,并将二级结构的共识预测为高度精确的三态Q3(螺旋,strand,和线圈)。这个预测是使用六种最近表现最好的方法来实现的:MUFOLD-SS,RaptorX,PSSpredv4,PSIPRED,JPredv4和Porter5.0。CSSP-2.0验证包括涉及来自PDB的各种蛋白质类别的数据集,CullPDB,和AlphaFold数据库。我们的结果表明,共识Q3预测的准确性有了显著提高。使用CSSP-2.0,晶体学可以从整个复杂结构中挑选出稳定的规则二级结构,这将有助于推断假设蛋白质的功能注释。Web服务器可在https://bioserver3免费获得。物理。iisc.AC.in/cgi-bin/cssp-2/.
    Studying the relationship between sequences and their corresponding three-dimensional structure assists structural biologists in solving the protein-folding problem. Despite several experimental and in-silico approaches, still understanding or decoding the three-dimensional structures from the sequence remains a mystery. In such cases, the accuracy of the structure prediction plays an indispensable role. To address this issue, an updated web server (CSSP-2.0) has been created to improve the accuracy of our previous version of CSSP by deploying the existing algorithms. It uses input as probabilities and predicts the consensus for the secondary structure as a highly accurate three-state Q3 (helix, strand, and coil). This prediction is achieved using six recent top-performing methods: MUFOLD-SS, RaptorX, PSSpred v4, PSIPRED, JPred v4, and Porter 5.0. CSSP-2.0 validation includes datasets involving various protein classes from the PDB, CullPDB, and AlphaFold databases. Our results indicate a significant improvement in the accuracy of the consensus Q3 prediction. Using CSSP-2.0, crystallographers can sort out the stable regular secondary structures from the entire complex structure, which would aid in inferring the functional annotation of hypothetical proteins. The web server is freely available at https://bioserver3.physics.iisc.ac.in/cgi-bin/cssp-2/.
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  • 文章类型: Journal Article
    The treatment of cow\'s milk protein allergy is based on the complete elimination of cow\'s milk protein from the diet. To achieve remission of symptoms and future tolerance, exclusion must be total. In formula fed infants the extensively hydrolysed formula is the most appropriate option in mild or moderate forms, while those based on amino acids are reserved for the most severe cases. The treatment time, the acquisition of tolerance and the moment for the oral provocation test will vary according to the clinical picture, the immunological mechanism involved and the age of the patient. The aim of this consensus has been to reflect the updated knowledge together with the experience of neonatologists, pediatricians, experts in allergy, nutrition and gastroenterology.
    El tratamiento de la alergia a las proteínas de la leche de vaca se basa en la eliminación completa de las proteínas de leche de vaca de la dieta del niño y de la madre en los que reciben leche materna. Para lograr la remisión de los síntomas y la tolerancia futura, la exclusión debe ser total. En los niños que reciben fórmula, esta deberá tener hidrolizado extenso de proteínas en las formas leves o moderadas, mientras que aquellas a base de aminoácidos se reservan para los casos más graves. El tiempo de tratamiento, la adquisición de tolerancia y el momento para la prueba de provocación oral van a variar según el cuadro clínico, el mecanismo inmunológico implicado y la edad del paciente. El objetivo de este consenso ha sido reflejar el conocimiento actualizado junto con la experiencia de neonatólogos, pediatras, especialistas en alergia, nutrición y gastroenterología.
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  • 文章类型: Journal Article
    抗微生物肽(AMP)是对抗对常规抗微生物药物具有抗性的病原体的有希望的候选物,因为它们通过涉及膜破坏的机制起作用。然而,AMP在临床环境中的使用受到限制,至少在某种程度上,与哺乳动物细胞相比,它们对蛋白水解降解的敏感性以及对病原微生物缺乏选择性。我们最近报道了以天然存在的α-螺旋AMPaurein1.2为模板的α-和β-肽寡聚体的设计。这些α/β-肽寡聚体比金黄蛋白1.2更蛋白水解稳定,并且具有使它们作为常规AMP的替代物具有吸引力的若干其它属性。这项研究描述了肽的理化性质对基于aurein1.2的α/β肽模拟物针对9种细菌的广谱活性的影响,真菌,和哺乳动物细胞系。我们使用偏最小二乘回归(PLSR)监督的机器学习模型来量化和可视化实验确定的物理化学性质之间的关系(例如,疏水性,charge,和螺旋度),并通过实验测量了149个成员的α/β肽文库中21种肽的细胞类型特异性活性。使用这种方法,我们确定了几种预测显示出增强的广谱选择性的肽,一种评估抗微生物活性相对于哺乳动物细胞毒性的措施,与金黄色葡萄球菌1.2相比。实验验证证明了高模型预测性能,和表征具有最高广谱选择性的化合物揭示了肽的疏水性,螺旋度,和螺旋刚性是广谱选择性的强大预测因子。从模型预测中鉴定出的最具选择性的肽在广谱选择性方面比金黄色葡萄球菌1.2提高了13倍以上,证明了使用PLSR模型鉴定含非标准氨基酸的肽的定量结构-功能关系的能力。总的来说,这项工作为螺旋抗菌α/β-肽的合理设计建立了可量化的指南,并确定了有希望的新的α/β-肽,相对于金黄色葡萄球菌1.2,其具有显着降低的哺乳动物毒性和改善的抗真菌和抗菌活性。
    Antimicrobial peptides (AMPs) are promising candidates to combat pathogens that are resistant to conventional antimicrobial drugs because they operate through mechanisms that involve membrane disruption. However, the use of AMPs in clinical settings has been limited, at least in part, by their susceptibility to proteolytic degradation and their lack of selectivity toward pathogenic microbes vs mammalian cells. We recently reported on the design of α- and β-peptide oligomers structurally templated upon the naturally occurring α-helical AMP aurein 1.2. These α/β-peptide oligomers are more proteolytically stable than aurein 1.2 and have several other attributes that render them attractive as alternatives to conventional AMPs. This study describes the influence of peptide physicochemical properties on the broad-spectrum activity of aurein 1.2-based α/β-peptide mimics against nine bacterial, fungal, and mammalian cell lines. We used a partial least-squares regression (PLSR)-supervised machine learning model to quantify and visualize relationships between experimentally determined physicochemical properties (e.g., hydrophobicity, charge, and helicity) and experimentally measured cell-type-specific activities of 21 peptides in a 149-member α/β-peptide library. Using this approach, we identified several peptides that were predicted to exhibit enhanced broad-spectrum selectivity, a measure that evaluates antimicrobial activity relative to mammalian cell toxicity compared to aurein 1.2. Experimental validation demonstrated high model predictive performance, and characterization of compounds with the highest broad-spectrum selectivity revealed peptide hydrophobicity, helicity, and helical rigidity to be strong predictors of broad-spectrum selectivity. The most selective peptide identified from the model prediction has more than a 13-fold improvement in broad-spectrum selectivity than that of aurein 1.2, demonstrating the ability of using PLSR models to identify quantitative structure-function relationships for nonstandard amino acid-containing peptides. Overall, this work establishes quantifiable guidelines for the rational design of helical antimicrobial α/β-peptides and identifies promising new α/β-peptides with significantly reduced mammalian toxicities and improved antifungal and antibacterial activities relative to aurein 1.2.
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  • 文章类型: Journal Article
    背景:对早产儿规定肠胃外营养(PN),直到通过肠内途径满足营养需求为止,但在这一人群中,关于PN最佳实践的问题仍未解决。
    方法:成立了一个跨学科委员会,以回答有关为早产儿提供PN的12个问题。建议的分级,评估,发展,并使用评估(等级)过程。关于肠胃外常量营养素剂量的问题,脂质注射乳剂(ILE)组合物,和临床相关结果,包括PNALD,儿童早期成长,和神经发育。排除患有先天性胃肠道疾病的早产儿或在研究进入时已经诊断为坏死性小肠结肠炎或PN相关肝病(PNALD)的婴儿。
    结果:委员会审查了2001年至2023年之间发表的2460篇引文,并评估了57项临床试验。对于大多数问题,证据质量很低。大多数分析在对照组之间没有显着差异。与含有100%大豆油的ILE相比,多组分油ILE与3期或更高级早产儿视网膜病变(ROP)的减少有关。对于所有其他问题,提供了专家意见。
    结论:在评估PN启动时机时,对照组之间的大多数临床结局没有显着差异,氨基酸剂量,和ILE组成。未来的临床试验应该标准化结果定义,以允许数据的统计合并,从而在未来的指南中允许更多基于证据的建议。该指南已获得ASPEN2022-2023年董事会的批准。
    Parenteral nutrition (PN) is prescribed for preterm infants until nutrition needs are met via the enteral route, but unanswered questions remain regarding PN best practices in this population.
    An interdisciplinary committee was assembled to answer 12 questions concerning the provision of PN to preterm infants. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) process was used. Questions addressed parenteral macronutrient doses, lipid injectable emulsion (ILE) composition, and clinically relevant outcomes, including PNALD, early childhood growth, and neurodevelopment. Preterm infants with congenital gastrointestinal disorders or infants already diagnosed with necrotizing enterocolitis or PN-associated liver disease (PNALD) at study entry were excluded.
    The committee reviewed 2460 citations published between 2001 and 2023 and evaluated 57 clinical trials. For most questions, quality of evidence was very low. Most analyses yielded no significant differences between comparison groups. A multicomponent oil ILE was associated with a reduction in stage 3 or higher retinopathy of prematurity (ROP) compared to an ILE containing 100% soybean oil. For all other questions, expert opinion was provided.
    Most clinical outcomes were not significantly different between comparison groups when evaluating timing of PN initiation, amino acid dose, and ILE composition. Future clinical trials should standardize outcome definitions to permit statistical conflation of data, thereby permitting more evidence based recommendations in future guidelines. This guideline has been approved by the ASPEN 2022-2023 Board of Directors.
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  • 文章类型: Journal Article
    目前占主导地位的严重急性呼吸道综合症冠状病毒2(SARS-CoV-2)的Omicron变体已迅速分化为进化枝。为了预测这些进化枝的可能影响,将进化枝整个基因组的共有插入/缺失(indel)和氨基酸置换与原始SARS-CoV-2株进行了比较。使用最大似然方法推断了进化枝和谱系代表的进化史,并使用Bootstrap方法进行了测试。发现indel和多态性氨基酸要么是进化枝特异性的,要么是进化枝之间共有的。21K进化枝具有独特的indel和替代者,这可能代表恢复的插入删除/替换。Omicron进化枝中似乎与SARS-CoV-2衰减有关的三个变异包括核衣壳基因的缺失,3\'未翻译区域中的删除,和开放阅读框中的截断8.系统发育分析表明,Omicron进化枝和谱系形成三个独立的簇。
    The currently dominant Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has swiftly diverged into clades. To predict the probable impact of these clades, the consensus insertions/deletions (indels) and amino acid substitutions of the whole genome of clades were compared with the original SARS-CoV-2 strain. The evolutionary history of representatives of clades and lineages was inferred using the maximum-likelihood method and tested using the bootstrap method. The indels and polymorphic amino acids were found to be either clade-specific or shared among clades. The 21K clade has unique indels and substitutions, which probably represent reverted indels/substitutions. Three variations that appear to be associated with SARS-CoV-2 attenuation in the Omicron clades included a deletion in the nucleocapsid gene, a deletion in the 3\'untranslated region, and a truncation in open reading frame 8. Phylogenetic analysis showed that the Omicron clades and lineages form three separate clusters.
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  • 文章类型: Journal Article
    进行了一项实验以检验以下假设:增加新型植酸酶的水平会增加饲喂给幼猪的饮食中营养素的表观回肠消化率(AID)和表观总道消化率(ATTD)。基于玉米的阴性对照(NC)饮食,豆粕,和含有约0.83%植酸盐的油菜粉(即,0.23%植酸结合的P)被配制为钙缺乏,P,和标准化的回肠可消化氨基酸(AA)。通过向NC饮食中添加250、500、1,000、2,000或4,000植酸酶单位/kg的新型植酸酶来配制5种额外的饮食。将18只回肠插管的猪(17.81±1.71kg)分配给6×3不完整的拉丁正方形设计,具有6种饮食和3个11天的周期。每个时期每个饮食有三头猪;因此,每个饮食有九只重复的猪。每个时期的最初5天被认为是饮食的适应期。对于每个时期,在第6,7,8和9天通过肛门刺激收集粪便样本,而在第10和11天使用标准程序收集回肠消化物.结果表明,粗蛋白的AID,不可或缺的AA,可有可无的AA增加(二次,P<0.05)随着日粮中微生物植酸酶浓度的增加。在1,000或2,000FTU/kg的饮食中加入新型植酸酶可使总AA的AID从73.7%增加到79.8%。微生物植酸酶水平的增加增加(二次,P<0.05)干物质和矿物质的AID(即Ca,P,K,Mg,Cu)在饮食中。同样,随着日粮中植酸酶含量的增加,灰分和Na的AID呈线性增加(P<0.05)。微生物植酸酶水平的增加增加(线性,P<0.01)日粮中总能量(GE)和淀粉的AID。灰分ATTD的二次增加(P<0.05),Ca,P,K,随着日粮中微生物植酸酶浓度的增加,在实验日粮中观察到Cu。Mg和GE的ATTD也随着饲料植酸酶浓度的增加而增加(线性;P<0.05)。总之,本实验中使用的新型微生物植酸酶可有效增加干物质的AID,GE,淀粉,矿物,AA,以及配制为钙缺乏的饮食中总能量和矿物质的ATTD,P,AA。
    微生物植酸酶对氨基酸(AA)消化率的影响一直不一致,但在许多实验中,使用相对较低水平的植酸酶,尚不清楚是否需要更高浓度的植酸酶来增加AA的消化率。最近开发了一种新的共有细菌6-植酸酶变体,但是不知道这种植酸酶是否会导致AA和其他营养素的消化率增加。因此,进行了一项实验来检验这样的假设,即饮食中包含增加水平的新型植酸酶(即,0、250、500、1,000、2,000和4,000植酸酶单位/kg)增加了AA的回肠消化率以及日粮中能量和矿物质的总道消化率。在这个实验中,结果表明,增加植酸酶水平增加了淀粉的表观回肠消化率,总能量,矿物,粗蛋白,AA,以及总能量和矿物质的表观总道消化率。植酸酶对AA消化率的影响可能取决于饮食组成,植酸和植酸酶的来源和浓度,和猪成熟;然而,需要进一步的研究来证实这一点。
    An experiment was conducted to test the hypothesis that increasing levels of a novel phytase increases the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients in diets fed to young pigs. A negative control (NC) diet based on corn, soybean meal, and canola meal that contained approximately 0.83% phytate (i.e., 0.23% phytate-bound P) was formulated to be deficient in Ca, P, and standardized ileal digestible amino acids (AA). Five additional diets were formulated by adding 250, 500, 1,000, 2,000, or 4,000 phytase units/kg of the novel phytase to the NC diets. Eighteen ileal-cannulated pigs (17.81 ± 1.71 kg) were allotted to a 6 × 3 incomplete Latin square design with six diets and three 11-day periods. There were three pigs per diet in each period; therefore, there were nine replicate pigs per diet. The initial 5 d of each period was considered an adaptation period to the diet. For each period, fecal samples were collected via anal stimulation on days 6, 7, 8, and 9, whereas ileal digesta were collected on days 10 and 11 using standard procedures. Results indicated that the AID of crude protein, indispensable AA, and dispensable AA was increased (quadratic, P < 0.05) as the concentration of microbial phytase increased in the diets. Dietary inclusion of the novel phytase at 1,000 or 2,000 FTU/kg increased the AID of total AA from 73.7% to 79.8%. Increasing levels of microbial phytase increased (quadratic, P < 0.05) the AID of dry matter and minerals (i.e., Ca, P, K, Mg, Cu) in the diets. Likewise, a linear increase (P < 0.05) in the AID of ash and Na was observed as the inclusion level of phytase increased in the diets. Increasing levels of microbial phytase increased (linear, P < 0.01) the AID of gross energy (GE) and starch in the diets. A quadratic (P < 0.05) increase in the ATTD of ash, Ca, P, K, and Cu in experimental diets was observed as the concentration of microbial phytase increased in the diets. The ATTD of Mg and GE also increased (linear; P < 0.05) as concentration of dietary phytase increased. In conclusion, the novel microbial phytase used in this experiment was effective in increasing the AID of dry matter, GE, starch, minerals, and AA, as well as the ATTD of gross energy and minerals in diets formulated to be deficient in Ca, P, and AA.
    The effect of microbial phytase on amino acid (AA) digestibility has been inconsistent, but in many experiments, relatively low levels of phytase were used and it is not known if greater concentrations of phytase are needed to increase AA digestibility. A novel consensus bacterial 6-phytase variant has been recently developed, but it is not known if this phytase results in increased digestibility of AA and other nutrients. Therefore, an experiment was conducted to test the hypothesis that dietary inclusion of increasing levels of the novel phytase (i.e., 0, 250, 500, 1,000, 2,000, and 4,000 phytase units/kg) increases ileal digestibility of AA and total tract digestibility of energy and minerals in diets for growing pigs. In this experiment, it was demonstrated that increasing levels of phytase increased the apparent ileal digestibility of starch, gross energy, minerals, crude protein, and AA, as well as the apparent total tract digestibility of gross energy and minerals. The impact of phytase on AA digestibility is possibly dependent on diet composition, phytate and phytase sources and concentrations, and pig maturity; however, further research is needed to confirm this.
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  • 文章类型: Journal Article
    鉴于营养不良作为人类慢性疾病的原因的重要性,令人惊讶的是,在医学院培训和临床实践中,营养很少受到关注。特定的维生素,矿物,脂肪酸,饮食中的氨基酸和水对健康至关重要,和不足导致或促成许多疾病。正确使用饮食指南和营养事实标签可以改善营养状况并导致健康饮食的消费。COVID-19改变了数百万人获得营养食品的途径,并提高了人们对饮食和免疫功能重要性的认识。提高对营养的认识将改善临床护理的结果。
    Given the importance of poor nutrition as a cause for human chronic disease, it is surprising that nutrition receives so little attention during medical school training and in clinical practice. Specific vitamins, minerals, fatty acids, amino acids and water in the diet are essential for health, and deficiencies lead or contribute to many diseases. Proper use of the dietary guidelines and nutrition facts labeling can improve nutritional status and lead to the consumption of a healthy diet. COVID-19 has altered access to nutritious foods for millions and increased awareness of the importance of diet and immune function. An improved appreciation for nutrition will improve the outcomes of clinical care.
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  • 文章类型: Journal Article
    基于蛋白质和肽的疫苗可能更安全,如果根据许多序列计算,比基于单一菌株设计的更广谱。设计了来自E2包膜蛋白B结构域的物理化学性质共有(PCPCon)甲病毒(AV)抗原,重组合成并显示出免疫原性(即接种后的血清在斑点和ELISA中检测到抗原)。接种基于单个AV物种的B区抗原后血清中的抗体(东部或委内瑞拉马脑炎(EEEVcon,VEEVcon),或者基孔肯雅(CHIKVcon)仅结合它们的同源蛋白,而针对多个物种设计的那些(Mosaikcon和EVCcon)识别所有三种血清型特异性抗原。VEEVcon和EEEVcon血清仅显示针对其相关菌株的抗病毒活性(在噬斑减少中和测定(PRNT50/80)中。将设计用于CHIKVcon的E2-A结构域的表面暴露区域的肽添加至CHIKVcon接种物以提供抗CHIKV抗体。EVCcon,基于三种不同的甲病毒,与来自AllAVcon的E2-A结构域肽结合,24种不同AV的PCPcon,产生广谱,抗VEEV的抗病毒抗体,EEEV和CHIKV,AV彼此具有小于35%的氨基酸同一性(>65%的多样性)。这是针对所有AV的分子定义疫苗的有希望的开始。对这些抗原的进一步研究可以阐明哪些区域对于强大的免疫反应最重要,对快速进化病毒的突变具有抗性。经验证的计算方法也可用于设计针对许多其他病原体家族的广谱抗原。
    Vaccines based on proteins and peptides may be safer and if calculated based on many sequences, more broad-spectrum than those designed based on single strains. Physicochemical Property Consensus (PCPcon) alphavirus (AV) antigens from the B-domain of the E2 envelope protein were designed, synthesized recombinantly and shown to be immunogenic (i.e. sera after inoculation detected the antigen in dotspots and ELISA). Antibodies in sera after inoculation with B-region antigens based on individual AV species (eastern or Venezuelan equine encephalitis (EEEVcon, VEEVcon), or chikungunya (CHIKVcon) bound only their cognate protein, while those designed against multiple species (Mosaikcon and EVCcon) recognized all three serotype specific antigens. The VEEVcon and EEEVcon sera only showed antiviral activity against their related strains (in plaque reduction neutralization assays (PRNT50/80). Peptides designed to surface exposed areas of the E2-A-domain of CHIKVcon were added to CHIKVcon inocula to provide anti-CHIKV antibodies. EVCcon, based on three different alphavirus species, combined with E2-A-domain peptides from AllAVcon, a PCPcon of 24 diverse AV, generated broad spectrum, antiviral antibodies against VEEV, EEEV and CHIKV, AV with less than 35% amino acid identity to each other (>65% diversity). This is a promising start to a molecularly defined vaccine against all AV. Further study with these antigens can illuminate what areas are most important for a robust immune response, resistant to mutations in rapidly evolving viruses. The validated computational methods can also be used to design broad spectrum antigens against many other pathogen families.
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  • 文章类型: Journal Article
    正电子发射断层扫描(PET)已广泛用于儿科肿瘤学。2-脱氧-2-[18F]氟-D-葡萄糖([18F]FDG)是用于PET成像的最常用的放射性药物。对于肿瘤脑成像,不同的氨基酸PET放射性药物已经在过去几年中被引入。本文件的目的是为影像专家和临床医生提供适应症指南,收购,并解释[18F]FDG和放射性标记的氨基酸PET在儿童患者的脑胶质瘤的影响。本文提出的所有建议都没有高水平的证据。相反,这些建议代表了该领域经验丰富的领导人的共识。对于[18F]FDG和放射性标记的氨基酸PET在小儿神经肿瘤学中的应用,需要进一步的研究以达成基于证据的建议。这些建议无意替代国家和国际法律或监管规定,应在核医学良好做法的背景下加以考虑。本指南/标准是由EANM和SNMMI与欧洲儿科肿瘤学会(SIOPE)脑肿瘤小组和儿科神经肿瘤学反应评估(RAPNO)工作组合作开发的。他们还总结了EANM的神经影像学和肿瘤学和Theranosics委员会的观点,并反映了EANM和其他社会不能对此负责的建议。
    Positron emission tomography (PET) has been widely used in paediatric oncology. 2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is the most commonly used radiopharmaceutical for PET imaging. For oncological brain imaging, different amino acid PET radiopharmaceuticals have been introduced in the last years. The purpose of this document is to provide imaging specialists and clinicians guidelines for indication, acquisition, and interpretation of [18F]FDG and radiolabelled amino acid PET in paediatric patients affected by brain gliomas. There is no high level of evidence for all recommendations suggested in this paper. These recommendations represent instead the consensus opinion of experienced leaders in the field. Further studies are needed to reach evidence-based recommendations for the applications of [18F]FDG and radiolabelled amino acid PET in paediatric neuro-oncology. These recommendations are not intended to be a substitute for national and international legal or regulatory provisions and should be considered in the context of good practice in nuclear medicine. The present guidelines/standards were developed collaboratively by the EANM and SNMMI with the European Society for Paediatric Oncology (SIOPE) Brain Tumour Group and the Response Assessment in Paediatric Neuro-Oncology (RAPNO) working group. They summarize also the views of the Neuroimaging and Oncology and Theranostics Committees of the EANM and reflect recommendations for which the EANM and other societies cannot be held responsible.
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  • 文章类型: Journal Article
    研究了将新型共有细菌6-植酸酶变体(PhyG)添加到植酸P(PP)含量高的日粮中时,对年轻肉鸡氨基酸(AA)和磷(P)的表观回肠消化率(AID)的影响。不添加无机磷酸盐(Pi)和可消化(dig)AA和代谢能(ME)。总共256只罗斯308只雄性肉鸡被分配到4种处理(8只鸟/笼,8个笼子/治疗),完全随机设计。治疗包括阳性对照(PC,2,975千卡/千克ME,3.7g/kg挖磷,2.83g/kgPP,8.4g/kgCa,10.6克/千克挖赖氨酸),阴性对照(NC),不添加Pi(ME-68kcal/kg,粗蛋白-10g/kg,挖AA-0.1至-0.4g/kg,Ca-2.0g/kg,挖P-2.2g/kg,Na-0.4g/kg与PC),和NC加上500或1,000FTU/kg的PhyG。测试日粮为玉米/大豆/菜籽粕/米糠,年龄为5至15天。在第15天收集回肠消化物和胫骨。在第12至15天期间收集排泄物以确定P保留。NC(vs.PC)降低(P<0.05)P保留(-10.4%单位),胫骨灰分(-14.3%单位),体重增加(-109克),采食量(-82克)和增加的FCR(从1.199到1.504),确认NC的营养和能量极度缺乏。植酸酶添加到NC线性(P<0.001)提高了性能,但由于NC中严重的营养/能量减少,并未将其完全恢复到PC的水平。植酸酶线性增加P保留(P<0.001),胫骨灰分(P<0.001),干物质含量(P<0.05),氮(P<0.01),总能量(P<0.05),全部17个个体AA(P<0.01)。在1,000FTU/kg时,植酸酶增加(P<0.05)与P保留PC和NC(+14.5和+24.9%单位,分别)和增加胫骨灰分与NC(+13.8%单位),相当于PC。NC降低了Cys的AID,Gly,Thr,和Metvs.PC(P<0.05)。在1,000FTU/kg时,植酸酶增加了所有17AA的AID。NC(P<0.01),相当于PC。在1,000FTU/kg时,AIDAA反应(高于NC)范围从+4.5%(Met)到+15.0%(Cys),对于必需的Thr(10.4%)和Val(8.2%)以及非必需的Cys(15.0%)和Gly(10.4%)最大。结果突出了PhyG在500至1,000FTU/kg的剂量水平下在年轻肉鸡中改善氮的回肠消化率的功效,AA,和能量以及P保留和胫骨灰分。性能数据强调需要在外源酶研究中将可消化的营养素摄入量作为响应变量。
    微生物植酸酶广泛用于商业肉鸡日粮中,以改善磷(P)的消化并减少其排泄到环境中。植酸酶可改善磷和其他营养素(包括氨基酸(AA))的消化。这项研究评估了在不添加任何无机P的情况下添加到营养减少饮食中的新型共有细菌6-植酸酶变体(PhyG)对幼龄肉鸡回肠中包括P和AA在内的营养物质消化率的影响。还评估了对P保留和骨矿化的影响。与未补充的阴性对照饮食相比,PhyG提高了生长性能,P保留,骨矿化(胫骨灰分),干物质消化率,氮,总能量,以及所有17个个体AA在孵化后5至15天期间,以剂量依赖性方式(剂量范围为每公斤饲料0至1,000植酸酶单位[FTU])。对于一些AA,在1,000FTU/kg时,PhyG的消化率显着增加(半胱氨酸:15.0%,苏氨酸:+10.4%),对于所有AA,都等同于营养充足的阳性对照(未补充)饮食产生的反应。结果表明,PhyG提高AA消化率和生长性能的功效,P保留,和年轻肉鸡的骨矿化。
    The effect of a novel consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) and phosphorus (P) utilization in young broilers when added to diets with high phytate-P (PP) content without added inorganic phosphate (Pi) and deficient in digestible (dig) AA and metabolizable energy (ME) was investigated. A total of 256 Ross 308 male broilers were assigned to 4 treatments (8 birds/cage, 8 cages/treatment) in a completely randomized design. Treatments comprised a positive control (PC, 2,975 kcal/kg ME, 3.7 g/kg dig P, 2.83 g/kg PP, 8.4 g/kg Ca, 10.6 g/kg dig lysine), a negative control (NC) without added Pi (ME -68 kcal/kg, crude protein -10 g/kg, dig AA -0.1 to -0.4 g/kg, Ca -2.0 g/kg, dig P -2.2 g/kg, Na -0.4 g/kg vs. PC), and NC plus 500 or 1,000 FTU/kg of PhyG. Test diets were corn/soy/rapeseed-meal/rice-bran-based and fed from 5 to 15 d of age. Ileal digesta and tibias were collected on day 15. Excreta was collected during days 12 to 15 to determine P retention. The NC (vs. PC) reduced (P < 0.05) P retention (-10.4% units), tibia ash (-14.3% units), weight gain (-109 g), feed intake (-82 g) and increased FCR (from 1.199 to 1.504), confirming that the NC was extremely deficient in nutrients and energy. Phytase addition to the NC linearly (P < 0.001) improved performance, but did not fully recover it to the level of the PC due to the severe nutrients/energy reduction in NC. Phytase linearly increased P retention (P < 0.001), tibia ash (P < 0.001), AID of dry matter (P < 0.05), nitrogen (P < 0.01), gross energy (P < 0.05), and all 17 individual AA (P < 0.01). At 1,000 FTU/kg, phytase increased (P < 0.05) P retention vs. PC and NC (+14.5 and +24.9% units, respectively) and increased tibia ash vs. NC (+13.8% units), equivalent to PC. The NC decreased AID of Cys, Gly, Thr, and Met vs. PC (P < 0.05). At 1,000 FTU/kg, phytase increased AID of all 17 AA vs. NC (P < 0.01), equivalent to PC. At 1,000 FTU/kg, AID AA responses (above NC) ranged from +4.5% (Met) to +15.0% (Cys), being maximal for essential Thr (+10.4%) and Val (+8.2%) and non-essential Cys (+15.0%) and Gly (+10.4%). The results highlight the efficacy of PhyG at a dose level of 500 to 1,000 FTU/kg in young broilers for improving the ileal digestibility of nitrogen, AA, and energy alongside P retention and tibia ash. The performance data emphasize the need to consider digestible nutrient intake as a response variable in exogenous enzyme studies.
    Microbial phytase is widely used in commercial broiler diets to improve digestion of phosphorus (P) and reduce its excretion into the environment. Phytase improves the digestion of phosphorus and other nutrients including amino acids (AA). This study evaluated the effect of a novel consensus bacterial 6-phytase variant (PhyG) added to a nutrient-reduced diet without any added inorganic P on the digestibility of nutrients including P and AA in the ileum of young broilers. Effects on P retention and bone mineralization were also assessed. Compared to an unsupplemented negative control diet, PhyG improved growth performance, P retention, bone mineralization (tibia ash), digestibility of dry matter, nitrogen, gross energy, and all 17 individual AA during 5 to 15 d post-hatch, in a dose-dependent manner (dose range 0 to 1,000 phytase units [FTU] per kilogram of feed). For some AA, the increases in digestibility with PhyG at 1,000 FTU/kg were substantial (cysteine: +15.0%, threonine:+10.4%), and for all AA were equivalent to the responses produced by a nutritionally adequate positive control (unsupplemented) diet. The results demonstrate the efficacy of PhyG to improve AA digestibility alongside growth performance, P retention, and bone mineralization in young broilers.
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