Synthetic Amino Acids Research Articles

English

Synthetic amino acid supplementation has provided facilities in the adjustment of feed formula, making it possible to obtain the required levels of essential amino acids. Lysine is pronounced the second greatest restrictive amino acid in broiler nutrition. The synthetic amino acid lysine is used as the orientation amino acid in poultry for the reason that it is mainly consumed for protein synthesis. In order to characterize the requirements of lysine, 240 male broilers of the lineage Avian Farms were kept in an environment with average temperature of 25.6°C. The 22 to 42 days old broilers presented initial average weight of 541 ± 3.6 g. The basal ration contained 19.57% of crude protein (CP), 3100 kcal of metabolizable energy (ME)/kg and 0.88% of total lysine, which was supplemented with 0.000, 0.076, 0.153, 0.230 and 0.306% de L-lysine hydrochloric acid (HCL), resulting in rations with 0.88, 0.94, 1.00, 1.06 and 1.12% of total lysine. The experimental design was completely randomized with five treatments of total lysine, six repetitions and eight broilers per repetition. During experiments, the temperature was kept at 25.6 ± 0.24°C, relative moisture ate 68.4 ± 6.30%, black globe temperature at 25.7 ± 0.25°C and the wet-bulb globe temperature (WBGT) at 74 ± 0.6°C. Treatments influenced the absolute weight of carcass, breast with bone, leg, thigh, abdominal fat and relative weight of breast with bone. Lysine levels had a quadratic effect over the food conversion (FC), which increased up to the level 1.03% of total lysine. Lysine levels had a quadratic influence over the weight gain (WG), which increased up to the level 1.05% of total lysine. Key words: Chickens for meat production, growth phase, lysine, thermal environment.

Novel signal peptides improve the secretion of recombinant Staphylococcus aureus Alpha toxinH35L in Escherichia coli

Secretion of heterologous proteins into Escherichia coli cell culture medium offers significant advantages for downstream processing over production as inclusion bodies; including cost and time savings, and reduction of endotoxin. Signal peptides play an important role in targeting proteins for translocation across the cytoplasmic membrane to the periplasmic space and release into culture medium during the secretion process. Alpha toxinH35L (ATH35L) was selected as an antigen for vaccine development against Staphylococcus aureus infections. It was successfully secreted into culture medium of E. coli by using bacterial signal peptides linked to the N-terminus of the protein. In order to improve the level of secreted ATH35L, we designed a series of novel signal peptides by swapping individual domains of modifying dsbA and pelB signal peptides and tested them in a fed-batch fermentation process. The data showed that some of the modified signal peptides improved the secretion efficiency of ATH35L compared with E. coli signal peptides from dsbA, pelB and phoA proteins. Indeed, one of the novel signal peptides improved the yield of secreted ATH35L by 3.5-fold in a fed-batch fermentation process and at the same time maintained processing at the expected site for signal peptide cleavage. Potentially, these new novel signal peptides can be used to improve the secretion efficiency of other heterologous proteins in E. coli. Furthermore, analysis of the synthetic signal peptide amino acid sequences provides some insight into the sequence features within the signal peptide that influence secretion efficiency.

Synthetic Biology—The Synthesis of Biology

Synthetic biology concerns the engineering of man-made living biomachines from standardized components that can perform predefined functions in a (self-)controlled manner. Different research strategies and interdisciplinary efforts are pursued to implement engineering principles to biology. The "top-down" strategy exploits nature's incredible diversity of existing, natural parts to construct synthetic compositions of genetic, metabolic, or signaling networks with predictable and controllable properties. This mainly application-driven approach results in living factories that produce drugs, biofuels, biomaterials, and fine chemicals, and results in living pills that are based on engineered cells with the capacity to autonomously detect and treat disease states in vivo. In contrast, the "bottom-up" strategy seeks to be independent of existing living systems by designing biological systems from scratch and synthesizing artificial biological entities not found in nature. This more knowledge-driven approach investigates the reconstruction of minimal biological systems that are capable of performing basic biological phenomena, such as self-organization, self-replication, and self-sustainability. Moreover, the syntheses of artificial biological units, such as synthetic nucleotides or amino acids, and their implementation into polymers inside living cells currently set the boundaries between natural and artificial biological systems. In particular, the in vitro design, synthesis, and transfer of complete genomes into host cells point to the future of synthetic biology: the creation of designer cells with tailored desirable properties for biomedicine and biotechnology.

Amino Acid Block Copolymers with Broad Antimicrobial Activity and Barrier Properties.

Antimicrobial properties of a long-chain, synthetic, cationic, and hydrophobic amino acid block copolymer are reported. In 5 and 60 min time-kill assays, solutions of K100 L40 block copolymers (poly(l-lysine·hydrochloride)100 -b-poly(l-leucine)40 ) at concentrations of 10-100 µg mL-1 show multi-log reductions in colony forming units of Gram-positive and Gram-negative bacteria, as well as yeast, including multidrug-resistant strains. Driven by association of hydrophobic segments, K100 L40 copolymers form viscous solutions and self-supporting hydrogels in water at concentrations of 1 and 2 wt%, respectively. These K100 L40 preparations provide an effective barrier to microbial contamination of wounds, as measured by multi-log decreases of tissue-associated bacteria with deliberate inoculation of porcine skin explants, porcine open wounds, and rodent closed wounds with foreign body. Based on these findings, amino acid copolymers with the features of K100 L40 can combine potent, direct antimicrobial activity and barrier properties in one biopolymer for a new approach to prevention of wound infections.

Feed efficiency, growth performance, and carcass characteristics of a fast- and a slower-growing broiler hybrid fed low- or high-protein organic diets

Organic poultry meat production in Sweden is characterized by diets based on organic and locally produced feedstuffs, roughage allowance, a long rearing period (>10 weeks), outdoor access for the birds, and ban of synthetic amino acids and prophylactic use of antibiotics and anthelmintic. Until recently, the main hybrids used in organic broiler chicken production in Sweden were the same as used in conventional broiler chicken production. These birds are bred to reach market weight at 5 to 6 weeks on a high-protein quality non-organic diet. In this study, organic high- and low-protein diets were fed to fast- and slower-growing hybrid broiler chickens with 5 pens per genotype × diet treatment and 21 to 22 broiler chickens per pen. Weight gain, feed conversion, health, and mortality were recorded during a 71-day rearing period. The fast-growing hybrid birds grew faster (55.4 ± 0.7 versus 38.3 ± 0.5 g/day, P = 0.001) and had a better feed conversion ratio (2.6 ± 0.1 versus 2.9 ± 0.1 kg feed/kg body weight, P = 0.001) than the slower-growing hybrid birds. The fast-growing hybrid birds grew slower when fed the high-protein compared to the low-protein diet (55.3 ± 0.5 versus 57.8 ± 1.4 g/day, P = 0.050), while the slower-growing hybrid birds grew faster when fed the high-protein compared to the low-protein diet (39.4 ± 0.7 and 37.2 ± 0.4 g/day, P = 0.038). A higher proportion of fast- compared to slower-growing hybrid birds had sticky droppings at 1 week of age (18.8 ± 1.6 versus 3.8 ± 1.6%, P = 0.001) and were culled because of leg weakness during the 10-week rearing period (10.0 ± 2.0 versus 3.3 ± 2.0%, P = 0.031), indicating poorer welfare among fast-growing hybrid birds when reared for 10 weeks on organic diets.

Evaluation of a novel sodium borocaptate-containing unnatural amino acid as a boron delivery agent for neutron capture therapy of the F98 rat glioma

BackgroundBoron neutron capture therapy (BNCT) is a unique particle radiation therapy based on the nuclear capture reactions in boron-10. We developed a novel boron-10 containing sodium borocaptate (BSH) derivative, 1-amino-3-fluorocyclobutane-1-carboxylic acid (ACBC)-BSH. ACBC is a tumor selective synthetic amino acid. The purpose of this study was to assess the biodistribution of ACBC-BSH and its therapeutic efficacy following Boron Neutron Capture Therapy (BNCT) of the F98 rat glioma.MethodsWe evaluated the biodistribution of three boron-10 compounds, ACBC-BSH, BSH and boronophenylalanine (BPA), in vitro and in vivo, following intravenous (i.v.) administration and intratumoral (i.t.) convection-enhanced delivery (CED) in F98 rat glioma bearing rats. For BNCT studies, rats were stratified into five groups: untreated controls, neutron-irradiation controls, BNCT with BPA/i.v., BNCT with ACBC-BSH/CED, and BNCT concomitantly using BPA/i.v. and ACBC-BSH/CED.ResultsIn vitro, ACBC-BSH attained higher cellular uptake F98 rat glioma cells compared with BSH. In vivo biodistribution studies following i.v. administration and i.t. CED of ACBC-BSH attained significantly higher boron concentrations than that of BSH, but much lower than that of BPA. However, following convection enhanced delivery (CED), ACBC-BSH attained significantly higher tumor concentrations than BPA. The i.t. boron-10 concentrations were almost equal between the ACBC-BSH/CED group and BPA/i.v. group of rats. The tumor/brain boron-10 concentration ratio was higher with ACBC-BSH/CED than that of BPA/i.v. group. Based on these data, BNCT studies were carried out in F98 glioma bearing rats using BPA/i.v. and ACBC-BSH/CED as the delivery agents. The corresponding mean survival times were 37.4 ± 2.6d and 44.3 ± 8.0d, respectively, and although modest, these differences were statistically significant.ConclusionsOur findings suggest that further studies are warranted to evaluate ACBC-BSH/CED as a boron delivery agent.

Expanding the genetic code in vertebrates.

Synthetic Biology Unnatural amino acids can be incorporated into target proteins by using a transfer RNA (tRNA)—aminoacyl-tRNA synthetase pair that adds an unnatural amino acid at an amber stop codon. The strategy has been used in prokaryotic and eukaryotic cells and for generating transgenic invertebrates. Chen et al. have succeeded in integrating a construct coding for the unnatural amino acid p -azido-phenylalanine (AzF) into the mouse genome. The artificial gene was transmitted to subsequent generations and caused no obvious physiological defects. Primary cells from adult transgenic mice incorporated AzF into a fluorescent reporter protein containing an amber codon. Similarly, the genetic code of zebrafish was expanded, and in vivo incorporation of AzF into reporter protein was achieved. This opens the potential to investigate the function of target proteins in living animals. Cell Res. 10.1038/cr.2016.145 (2016).

Fast Diazaborine Formation of Semicarbazide Enables Facile Labeling of Bacterial Pathogens.

Bioorthogonal conjugation chemistry has enabled the development of tools for the interrogation of complex biological systems. Although a number of bioorthogonal reactions have been documented in literature, they are less ideal for one or several reasons including slow kinetics, low stability of the conjugated product, requirement of toxic catalysts, and side reactions with unintended biomolecules. Herein we report a fast (>103 M-1 s-1) and bioorthogonal conjugation reaction that joins semicarbazide to an aryl ketone or aldehyde with an ortho-boronic acid substituent. The boronic acid moiety greatly accelerates the initial formation of a semicarbazone conjugate, which rearranges into a stable diazaborine. The diazaborine formation can be performed in blood serum or cell lysates with minimal interference from biomolecules. We further demonstrate that application of this conjugation chemistry enables facile labeling of bacteria. A synthetic amino acid D-AB3, which presents a 2-acetylphenylboronic acid moiety as its side chain, was found to incorporate into several bacterial species through cell wall remodeling, with particularly high efficiency for Escherichia coli. Subsequent D-AB3 conjugation to a fluorophore-labeled semicarbazide allows robust detection of this bacterial pathogen in blood serum.

Effects of Supplemental Dietary Glutamine and Arginine on Broiler Live Performance, Blood Chemistry, and Incidence of White Striping and Wooden Breast

ObjectivesThe broiler industry has been recently plagued with muscle myopathies, namely wooden breast (WB) and white striping (WS). These myopathies negatively affect the most valuable cut of a broiler, the pectoralis major muscle, whereby there is reduced protein content and increased fat and collagen content, resulting in reduced meat quality and consumer preference. The current cause of WB and WS in broilers is yet to be fully elucidated. One theory is that increased corn prices, availability of distiller’s dry grains with solubles, and other food industry co-products have led to less soybean meal and more synthetic amino acids in broiler diets can result in marginal dietary levels of glutamine (Gln) and amino acids such as arginine (Arg). It was hypothesized that increasing intracellular Gln and Arg may relate to an increased rate of protein synthesis, decreased inflammatory immune responses, a reduction of muscle proteolysis, and consequently a reduced incidence of WB and WS.Materials and MethodsA total of 288 male broiler chicks were allocated to 1 of 4 diets that had 0 or 1% supplemental Gln or 0 or 0.25% supplemental Arg to complete a 2x2 factorial design. Chicks were housed in Alternative Design cages with 8 chicks/cage and 9 replicates/treatment. Individual body weights (BW) were recorded weekly, blood chemistry was analyzed at 28 and 41 d using iStat, and 2 birds/pen were scored for WB and WS after being harvested at 42 d of age. Shear force, drip loss, cook loss, and meat pH were then evaluated. Data were analyzed using PROC GLM and PROC MIXED on SAS (SAS Inst. Inc., Cary, NC).ResultsThere were no differences among feed conversion ratio, BW, or WS. Total carbon dioxide, partial pressure of oxygen, and pH of the blood at 28 d were reduced by supplementing Gln at 1% (P < 0.05). Similarly, the base excess extracellular fluid and potassium of the blood at 28 d were reduced by supplementing Gln at 1% (P < 0.01). Broilers fed diets with Arg or Gln alone exhibited significantly greater WB incidence when compared to those fed the control (0% Gln and 0% Arg) or combined interaction levels of 1% Gln and 0.25% Arg (P < 0.05).ConclusionThese data demonstrated that Gln and Arg were able to reduce the incidence of WB when supplemented simultaneously as opposed to individually in broiler diets.

Comparative Efficacy of Herbal Combined Amino Acid with Synthetic Amino Acid Supplemention on Egg Quality Parameters of White Leghorn Layers

An experiment was undertaken to evaluate the comparative efficacy of herbal combined amino acid with synthetic amino acid supplementation on egg quality parameters. To carry out the experiment, 240 BV300 pullets of 20 weeks age were selected and randomly distributed into five groups using complete randomized design (RBD). Each Treatment group comprised of 48 layer birds and was replicated four times with twelve birds. Negative Control group (T0) was fed basal diet completely devoid of lysine and biotin and with partial deficiency of methionine and choline, from 20th -41th week of age. Treatment groups fed basal diet deficient in amino acids and supplemented with herbal combined amino acid at different dose. An eggs collected were examined for exterior and interior egg quality. The results of present study revealed that basal diet supplemented with herbal combined amino acid significantly increased egg production, egg weight and egg mass. Feed cost per egg and feed efficiency was at par to that of control. Highest Yolk weight was recorded for herbal combined amino acid supplemented group. The supplementation of herbal combined amino acid alternatives of synthetic amino acid succeeded in improving the shell thickness. Hence, it is concluded that diet with herbal combined amino acid Formula Av/Cap/18 @ 200g/100kg of feed of feed from 20th to 41th week is most beneficial for improving egg production, egg weight, egg mass and shell thickness.

Starch and protein digestive dynamics in low-protein diets supplemented with crystalline amino acids

Digestive dynamics of starch and protein is defined as digestion of starch and protein, absorption of glucose and amino acids from the gut lumen and their transition across enterocytes to enter the portal circulation. Digestive dynamics consider the extent, rate and site of nutrient digestion along the small intestine and the bilateral, post-enteral bioavailability of glucose and amino acids. The underlying premise is that glucose and amino acids should be made available in appropriately balanced quantities at the sites of protein synthesis for efficient protein deposition and growth performance. Previous studies have suggested that feed conversion efficiency may be enhanced by rapidly digestible protein and that crystalline amino acids could be considered sources of ‘rapid protein’. At present, crystalline lysine, methionine and threonine are routinely included in broiler diets; moreover, an increasing array of both essential and non-essential crystalline amino acids is becoming commercially available. Despite unrestricted feed access in commercial chicken-meat production systems during the period of illumination, it appears that the intermittent feed consumption patterns of broiler chickens still provide scope for asynchronies in digestion and absorption of nutrients, which affects broiler performance. A better understanding of the post-enteral, bilateral bioavailability of glucose and amino acids in low-protein diets containing high levels of synthetic amino acids is clearly desirable and this applies equally to the relationship between crystalline and protein-bound amino acids.

Study on Comparative Efficacy of AV/CAP/18 With Synthetic Amino Acid Supplementation on Broiler Growth and Performance

Study on Comparative Efficacy of AV/CAP/18 With Synthetic Amino Acid Supplementation on Broiler Growth and Performance

Nano-hemostats and a Pilot Study of Their Use in a Large Animal Model of Major Vessel Hemorrhage in Endoscopic Skull Base Surgery.

Nano-hemostats are synthetic amino acid chains that self-assemble into a scaffold under certain conditions. These have been shown to be effective in stopping bleeding in small animal models of hemorrhage. Proposed mechanisms for their effect are that they form a mesh analogous to the fibrin plug in native hemostasis and that they may potentiate both platelet activation and the coagulation cascade. These may potentially become valuable adjuncts to endoscopic skull base surgery where there is the potential for both major vessel injury and smaller perforator injury to eloquent areas where bipolar cautery may not be suitable. We present a summary of the clinical studies to date and a small pilot study of nano-hemostat in an endoscopic sheep model of major vessel hemorrhage to determine its efficacy in stopping bleeding in this potentially catastrophic complication.

A Protocol for the Design of Protein and Peptide Nanostructure Self-Assemblies Exploiting Synthetic Amino Acids.

In recent years there has been increasing interest in nanostructure design based on the self-assembly properties of proteins and polymers. Nanodesign requires the ability to predictably manipulate the properties of the self-assembly of autonomous building blocks, which can fold or aggregate into preferred conformational states. The design includes functional synthetic materials and biological macromolecules. Autonomous biological building blocks with available 3D structures provide an extremely rich and useful resource. Structural databases contain large libraries of protein molecules and their building blocks with a range of sizes, shapes, surfaces, and chemical properties. The introduction of engineered synthetic residues or short peptides into these building blocks can greatly expand the available chemical space and enhance the desired properties. Herein, we summarize a protocol for designing nanostructures consisting of self-assembling building blocks, based on our recent works. We focus on the principles of nanostructure design with naturally occurring proteins and synthetic amino acids, as well as hybrid materials made of amyloids and synthetic polymers.

Evaluation of Prostate Cancer with Radiolabeled Amino Acid Analogs.

Conventional imaging of prostate cancer has limitations related to the frequently indolent biology of the disease. PET is a functional imaging method that can exploit various aspects of tumor biology to enable greater detection of prostate cancer than can be provided by morphologic imaging alone. Radiotracers that are in use or under investigation for targeting salient features of prostate cancer include those directed to glucose, choline, acetate, prostate-specific membrane antigen, bombesin, and amino acids. The tumor imaging features of this last class of radiotracers mirror the upregulation of transmembrane amino acid transport that is necessary in carcinomas because of increased amino acid use for energy requirements and protein synthesis. Natural and synthetic amino acids radiolabeled for PET imaging have been investigated in prostate cancer patients. Early work with naturally occurring amino acid-derived radiotracers, such as l-11C-methionine and l-1-11C-5-hydroxytryptophan, demonstrated promising results, including greater sensitivity than 18F-FDG for intraprostatic and extraprostatic cancer detection. However, limitations with naturally occurring amino acid-derived compounds, including metabolism of the radiotracer itself, led to the development of synthetic amino acid radiotracers, which are not metabolized and therefore more accurately reflect transmembrane amino acid transport. Of the synthetic amino acid-derived PET radiotracers, anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid (18F-FACBC or 18F-fluciclovine) has undergone the most promising translation to human use, including the availability of simplified radiosynthesis. Several studies have indicated advantageous biodistribution in the abdomen and pelvis with little renal excretion and bladder activity-characteristics beneficial for prostate cancer imaging. Studies have demonstrated improved lesion detection and diagnostic performance of 18F-fluciclovine in comparison with conventional imaging, especially for recurrent prostate cancer, although issues with nonspecific uptake limit the potential role of 18F-fluciclovine in the diagnosis of primary prostate cancer. Although work is ongoing, recently published intrapatient comparisons of 18F-fluciclovine with 11C-choline reported higher overall diagnostic performance of the former, especially for the detection of disease relapse. This review is aimed at providing a detailed overview of amino acid-derived PET compounds that have been studied for use in prostate cancer imaging.

1206 The effect of reduced crude protein, synthetic amino acid supplemented diets on nutrient excretion in wean to finish swine

1206 The effect of reduced crude protein, synthetic amino acid supplemented diets on nutrient excretion in wean to finish swine

Impact of 18F-Fluciclovine PET on Target Volume Definition for Postprostatectomy Salvage Radiotherapy: Initial Findings from a Randomized Trial.

The purpose of this study was to evaluate the role of the synthetic amino acid PET radiotracer 18F-fluciclovine in modifying the defined clinical and treatment-planning target volumes in postprostatectomy patients undergoing salvage radiotherapy and to evaluate the resulting dosimetric consequences to surrounding organs at risk. Methods: Ninety-six patients were enrolled in a randomized, prospective intention-to-treat clinical trial for potential salvage radiotherapy for recurrent prostate cancer after prostatectomy. The initial treatment plan was based on the results from conventional abdominopelvic CT and MRI. The 45 patients in the experimental arm also underwent abdominopelvic 18F-fluciclovine PET/CT, and the images were registered with the conventional images to determine whether the results would modify the initial treatment plan. The 51 patients in the control arm did not undergo 18F-fluciclovine PET/CT. For each patient, the clinical and treatment-planning target volumes that would have been treated before 18F-fluciclovine registration were compared with those after registration. For organs at risk (rectum, bladder, and penile bulb), the volumes receiving 40 Gy and 65 Gy before registration were compared with those after registration. Statistical comparisons were made using the paired t test. Acute genitourinary and gastrointestinal toxicity as defined by the Radiation Therapy Oncology Group was compared between the control and experimental arms using the χ2 test. Results: In 24 cases, radiotherapy was planned to a clinical target volume consisting of the prostate bed alone (CTV) (64.8-66.6 Gy). In 21 cases, radiotherapy was planned to a clinical target volume consisting of the pelvis (CTV1) (45.0 Gy) followed by a boost to the prostate bed (CTV2) (19.8-25.2 Gy). In each case, the respective treatment-planning target volume expansion (PTV, PTV1, or PTV2) was 0.8 cm (0.6 cm posterior). With the exception of PTV2, all postregistration volumes were significantly larger than the corresponding preregistration volumes. Analysis of the rectum, bladder, and penile bulb volumes receiving 40 Gy and 60 Gy demonstrated that only the penile bulb volumes were significantly higher after registration. No significant differences in acute genitourinary or gastrointestinal toxicity were observed. Conclusion: Including information from 18F-fluciclovine PET in the treatment-planning process led to significant differences in the defined target volume, with higher doses to the penile bulb but no significant differences in rectal or bladder dose or in acute genitourinary or gastrointestinal toxicity. Longer follow-up is needed to determine the impact of 18F-fluciclovine PET on cancer control and late toxicity endpoints.

Effect of dietary supplementation with amino acids on boar sperm quality and fertility

The aim of this study was to evaluate the effects of dietary supplementation with amino acids on sperm quality and fertility rates after insemination with boar semen. Twelve Yorkshire boars were paired by age and allocated to one of two dietary treatments composed of total lysine levels of 0.64% (T1) and 0.96% (T2), with the lysine: methionine: threonine: tryptophan: valine ratio in the diets set to 100:27:73:19:69 through the addition of synthetic amino acids. Semen was collected twice weekly (phase 1, 1–12 wk); every other day (phase 2, 13–16 wk); twice weekly (phase 3, 17–26 wk); and daily (phase 4, 27–28 wk). Semen was collected from boars during phase 3 and used to inseminate 64 multiparous sows. Our results showed that sperm concentration and total sperm cells were greater in boars in T2 than in boars in T1 in phases 2 and 4 (P<0.05). Sperm motility parameters, morphologically normal sperm, and acrosome integrity in T2 boars were greater than those in T1 boars (P<0.05) during the experiment. Free amino acid concentrations in seminal plasma increased in T2 boars (P<0.05). Furthermore, sows inseminated with semen collected from T2 boars gave birth to more live piglets than those inseminated with semen collected from T1 boars (P=0.04). In conclusion, supplementation of boar diet with amino acids improves sperm quality, and subsequently increases fertilization capacity and the number of live piglets.

Sunflower meal as a nutritional and economically viable substitute for soybean meal in diets for free-range laying hens

Alternative feedstock which may partially or fully replace conventional ingredients and consequently reduce the cost of egg production have been sought for a long time. In this context, the aim of this study was to evaluate the performance, egg quality and profitability of Naked Neck laying hens fed different levels of sunflower meal in place of soybean meal. A total of 128 hens were used, distributed in a completely randomized design, 16 boxes with eight hens each. The treatments consisted of one reference diet (RD) and three diets replacing the crude protein of soybean meal with sunflower meal at levels of 10%, 20% and 30% (R10, R20 and R30, respectively), properly supplemented with synthetic amino acids. All diets were based on the nutritional requirements of the semi-heavy laying hens. There was no significant difference of the different levels of substitution of soybean meal by sunflower meal on the laying rate (P=0.14), egg mass (P=0.06), feed conversion (P=0.20) and egg weight (P=0.35). However, for egg quality yolk color showed significant effects at different levels of substitution. The economic analysis of dietary treatments showed a reduction in the price per kilogram of soybean meal (0.59; 0.57; 0.55 and 0.53 dollars, respectively) replaced by sunflower meal at levels of 0%, 10%, 20% and 30% protein gross. Thus, the partial replacement of crude protein of soybean meal by sunflower meal in diets for hens is economically feasible, provided that the amino acid profile is corrected through supplementation, allowing the maintenance of the main quantitative and qualitative indices.

Biological evaluation of new [18F]F‐labeled synthetic amino acid derivatives as oncologic radiotracers

The present study evaluated the tumoral uptake of the novel synthetic amino acid positron emission tomography (PET) tracers (S)-2-amino-3-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)propanoic acid (AMC-101), (S)-2-amino-4-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)butanoic acid (AMC-102), and (S)-2-amino-5-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)pentanoic acid (AMC-103), all of which are (S)-2-amino-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)alkyl acids. In vitro cellular uptake was investigated using the rat glioma cell lines 9L and C6. In vitro competitive inhibition tests were performed to identify the involvement of specific amino acid transporters. In vivo dynamic PET images of 9L xenograft tumor-bearing model mice were acquired over 2 h after AMC administration. [(18) F]FDOPA PET studies were performed with and without S-carbidopa pretreatment for comparison. All three AMCs exhibited good in vitro cell uptake through the L and alanine-serine-cysteine transporters and enabled clear tumor visualization on PET, leaving the brain devoid of the tracer. Thirty minutes after injection, the mean tumor standardized uptake values were 1.59 ± 0.05, 1.89 ± 0.27, and 1.74 ± 0.13 for AMC-101, AMC-102, and AMC-103, respectively. Although the tumor uptake values of AMCs were lower than that of [(18) F]FDOPA with S-carbidopa pretreatment, AMCs enabled higher contrast images with lower background activity compared with [(18) F]FDOPA with S-carbidopa pretreatment. Our results indicate the potential uses of these new synthetic amino acids as oncologic radiotracers.