Amino acid analysis utilizing phenylisothiocyanate derivatives

Chemoselective Proteomics, Zinc Fingers, and a Zinc(II) Model for H2S Mediated Persulfidation

The gasotransmitter hydrogen sulfide (H2S) is thought to be involved in the post-translational modification of cysteine residues to produce reactive persulfides. A persulfide-specific chemoselective proteomics approach with mammalian cells has identified a broad range of zinc finger (ZF) proteins as targets of persulfidation. Parallel studies with isolated ZFs show that persulfidation is mediated by ZnII, O2, and H2S, with intermediates involving oxygen- and sulfur-based radicals detected by mass spectrometry and optical spectroscopies. A small molecule ZnII complex exhibits analogous reactivity with H2S and O2, giving a persulfidated product. These data show that ZnII is not just a biological structural element, but also plays a critical role in mediating H2S-dependent persulfidation. ZF persulfidation appears to be a general post-translational modification and a possible conduit for H2S signaling. This work has implications for our understanding of H2S-mediated signaling and the regulation of ZFs in cellular physiology and development.

The effects of different impeller combinations in the Sphingan WL gum fermentation process

The fermentation of the high-viscosity polysaccharide WL gum has always been associated with poor mass transfer. Appropriate impeller configurations are key factors in maintaining homogeneity and sufficient mass transfer conditions. Therefore, a flat-folded disc turbine impeller (FFDT) taking into account both the reduced cavitation effect and the increased contact area was designed. Besides, a curved cross impeller (CC) and a fishbone-shaped impeller (FS) generating axial flow were also designed. The energy consumption and efficiency of the designed impellers and eight reported impellers were evaluated through fermentation and principal component analysis (PCA). Compared to the commonly-used six-blade flat-blade disc turbine (FBDT), the ungassed power number of FFDT was reduced by 50 %. Combinations of six-blade Brumajin impeller (BM) + FFDT and CC + FFDT produced high WL gum production and viscosity (34.0 g/L, 35.50 g/L, and 62.64 Pa·s, 61.68 Pa·s, respectively) and were suitable impellers for WL biosynthesis. WL gum from BM + FFDT showed higher viscosity, viscoelasticity, and molecular weight than that from FBDT + FBDT. In addition, fewer amino acids and pyruvic acid intermediates were formed using BM + FFDT, indicating a greater metabolic flux towards WL gum synthesis. This work provided an important reference for the design of impellers in high-viscosity fermentation systems.

Plasma Cholesterol- and Body Fat-Lowering Effects of Chicken Protein Hydrolysate and Oil in High-Fat Fed Male Wistar Rats

Rest raw materials provide a new source of bioactive dietary ingredients, and this study aimed to determine the health effects of diets with chicken protein hydrolysate (CPH) and chicken oil (CO) generated from deboned chicken meat. Male Wistar rats (n = 56) were divided into seven groups in three predefined sub-experiments to study the effects of protein source (casein, chicken fillet, pork fillet, and CPH), the dose-effect of CPH (50% and 100% CPH), and the effects of combining CPH and CO. Rats were fed high-fat diets for 12 weeks, and casein and chicken fillet were used as controls in all sub-experiments. While casein, chicken-, or pork fillet diets resulted in similar weight gain and plasma lipid levels, the CPH diet reduced plasma total cholesterol. This effect was dose dependent and accompanied with the reduced hepatic activities of acetyl-CoA carboxylase and fatty acid synthase. Further, rats fed combined CPH and CO showed lower weight gain, and higher hepatic mitochondrial fatty acid oxidation, plasma L-carnitine, short-chain acylcarnitines, TMAO, and acetylcarnitine/palmitoylcarnitine. Thus, in male Wistar rats, CPH and CO lowered plasma cholesterol and increased hepatic fatty acid oxidation compared to whole protein diets, pointing to potential health-beneficial bioactive properties of these processed chicken rest raw materials.

Chemical composition, energy and nutritional values, digestibility and functional properties of defatted flour, protein concentrates and isolates from Carbula marginella (Hemiptera: Pentatomidae) and Cirina butyrospermi (Lepidoptera: Saturniidae)

Edible insects constitute a potential source of alternative proteins as a food supplement. The present study aimed to investigate the chemical composition, energy and nutritional values, the digestibility and functional properties of Carbula marginella (Thunberg) and Cirina butyrospermi (Vuillet) defatted flour, protein concentrates, and isolates. Carbula marginella has shown the highest content of protein (41.44%), lipid (51.92%), calcium (33.92 mg/100 g) and sodium (185.84 mg/100 g) while the highest contents of carbohydrate (34.54%), ash (4.77%), iron (31.27 mg/100 g), magnesium (150.09 mg/100 g), and potassium (1277 mg/100 g) have been observed for C. butyrospermi. Linoleic (30.23%), palmitic (27.54%), oleic (26.41%) and stearic (8.90%) acids were the most dominant fatty acids found in C. marginella. Cirina butyrospermi was characterized by high levels of oleic (27.01%), stearic (21.02%), linolenic (20.42%), palmitic (13.06%), and linoleic (8.01%) acids. Protein and essential amino acid contents of the protein isolates in both insect species were 1.7–2 times higher than that of their defatted flours. The protein isolate of C. marginella exhibited the highest protein digestibility (87.63%), while the highest fat absorption capacity (8.84 g/g) and foaming capacity (48.40%) have been obtained from the protein isolate of C. butyrospermi. These findings indicate that the protein concentrates and isolates of C. marginella and C. butyrospermi have great potential for industrial applications.

The effects of blanching on composition and modification of proteins in navy beans (Phaseolus vulgaris)

Blanching is an important process in the preparation of navy beans (Phaseolus vulgaris L.) for canning. We here explore the effect of blanching which can profoundly affect protein composition and introduce protein-primary-level modifications. Amino acid analysis showed significantly decreased protein abundance (58.5%) in blanched beans compared to raw beans. Proteomic analyses revealed a decrease in high molecular weight isoforms of the major storage globulin proteins phaseolin (mean fold-change -3.7) and legumin (mean fold-change -2.5) and concomitant increase in their low molecular weight isoforms (mean fold-change 6.4 and 8.3, respectively). Blanched beans also had decreased abundance of lipoxygenase (mean fold-change -13.1), an enzyme responsible for product spoilage during storage. Increased lysinoalanine (up to 47%) and highly modified protein fragments were found in the processing waters, indicating heat- induced modifications. Correlating these molecular level changes thus provides a basis for evaluating how processing parameters can be modified to increase protein food quality.

Simple and reliable serotonin assay in human serum by LC-MS/MS method coupled with one step protein precipitation for clinical testing in patients with carcinoid tumors

Serotonin (5-hydroxytryptamine, 5-HT) is readily secreted in patients with carcinoid tumors, especially arising from the midgut. Although serotonin assay in human plasma or whole blood has been extensively studied, serotonin assay in human serum by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has received much less attention. In this study, a simple and reliable LC-MS/MS method based on one step protein precipitation for sample pretreatment was developed for clinical assay of serum serotonin. Namely, 150 μL of serum was mixed with 50 μL of internal standard (IS) and 200 μL of 4 wt.% 5-sulfosalicylic acid (SSA) solution for protein precipitation. The supernatant after centrifugation was analyzed directly without further treatment. This method was validated for consistent linearity from 0.94 to 240 ng/mL with CVs ≤ 11.7%, good recovery in the range of 87.5%-104%, excellent analyte stability and low carryover. No obvious matrix effect was observed. Intra- and inter-day imprecision were below 8.03% and 11.5% respectively. Dilution linearity was verified with satisfying linearly dependent coefficients (r² = 0.9937). The reference interval of serotonin was established from 126 results derived from subjects without carcinoid tumors. Therefore, apart from development of a serum serotonin assay by the LC-MS/MS method, the reference interval (RI) of 5-HT has also been established for clinical testing in patients with carcinoid tumors. In addition, this method has been successfully used in our laboratory, indicating that this robust LC-MS/MS assay with simple sample preparation and short analysis time could offer inspiring potential for clinical testing of 5-HT in routine clinical laboratories.

Increasing γ-Aminobutyric Acid Content in Vegetable Soybeans via High-Pressure Processing and Efficacy of Their Antidepressant-Like Activity in Mice

This study applied high-pressure processing (HPP) technology to enrich the gamma aminobutyric acid (GABA) content in vegetable soybeans and evaluated its antidepressant efficacy on mice, with depression induced by the unpredictable chronic mild stress (UCMS) model. The optimal conditions for HPP, storage time, and storage temperature, as well as antidepressant-like effects of vegetable soybeans, were evaluated and discussed. HPP could effectively and significantly increase GABA content in soybean, with optimum conditions at 200 MPa. The GABA content in the whole vegetable soybean was 436.05 mg/100 g. In mice animal tests, the tail suspension test (TST) showed that the immobility time of the GABA group was significantly shorter than that of the control group. The total travel distance in the open field test (OFT) showed that depressed mice fed with the GABA feed exhibited exploratory behavior. The GABA group showed a significantly higher degree of sucrose preference than the control group. Both results indicate that the GABA feed could effectively alleviate depressive symptomatology. Regarding biochemical parameters, the fecal and serum corticosterone (CORT) levels in the control group increased to 104.86 pg/mg after the onset of depression. In contrast, the fecal CORT level in the GABA group was significantly reduced to 23.98 pg/mg and was comparable to that in the control group (33.38 pg/mg). Reduced serum CORT level in the GABA group suggests an improvement in depressive symptomatology. The serotonin concentration was maintained in the GABA group after the induction of depression, suggesting its preventive activity. The HPP GABA-enriched soybeans exerted modulatory effects on the behaviors of depressed mice and displayed a potential for commercialization.

Characterization of the development stages and roles of nutrients and other environmental factors in green tides in the Southern Yellow Sea, China

Large-scale floating green tides in the Southern Yellow Sea (SYS) caused by the macroalgal species Ulva prolifera have been recurring for 13 years and have become one of the greatest marine ecological disasters in the world. In this study, we attempt to explore the development pattern of green tides and find its key environmental influencing factors. The satellite remote sensing data of the development process of green tides fit the logistic growth curve (R² = 0.93, P < 0.01) well, showing three distinct growth phases (lag, exponential growth, and short plateau phases). Correspondingly, the green tide-drifting area from the coast of Jiangsu to the nearshore waters of the Shandong Peninsula was divided into three sections: the lag phase zone (A), the exponential growth phase zone (B), and the plateau phase zone (C). Zone A in the south of Jiangsu coastal waters had abundant inorganic nutrients that were indispensable to the green tide initiation. Zone B was mainly located out of Haizhou Bay, south of 34.5° N and north of 35.5° N, where approximately 80% of the green tide biomass was generated. The rich bioavailable nutrient sources, suitable temperature, and irradiance in this area were the main promotion factors for the rapid growth and scale expansion of green tides. Wet precipitation in zone B in May and June also played an important role in the final scale of green tides. Zone C had poor nutrients, increasing temperature, and irradiance (high transparency), which limited the continued expansion of green tides, and organic nutrients might be an important support to green tides development in this region. The study based on the growth phases of green tides could help us further understand the eutrophication mechanism in the green tide outbreaks in SYS.

Increased salt tolerance in Zymomonas mobilis strain generated by adaptative evolution

BACKGROUND

Ethanologenic alphaproteobacterium Zymomonas mobilis has been acknowledged as a promising biofuel producer. There have been numerous efforts to engineer this species applicable for an industrial-scale bioethanol production. Although Z. mobilis is robustly resilient to certain abiotic stress such as ethanol, the species is known to be sensitive to saline stress at a mild concentration, which hampers its industrial use as an efficient biocatalyst. To overcome this issue, we implemented a laboratory adaptive evolution approach to obtain salt tolerant Z. mobilis strain.

RESULTS

During an adaptive evolution, we biased selection by cell morphology to exclude stressed cells. The evolved strains significantly improved growth and ethanol production in the medium supplemented with 0.225 M NaCl. Furthermore, comparative metabolomics revealed that the evolved strains did not accumulate prototypical osmolytes, such as proline, to counter the stress during their growth. The sequenced genomes of the studied strains suggest that the disruption of ZZ6_1149 encoding carboxyl-terminal protease was likely responsible for the improved phenotype.

CONCLUSIONS

The present work successfully generated strains able to grow and ferment glucose under the saline condition that severely perturbs parental strain physiology. Our approach to generate strains, cell shape-based diagnosis and selection, might be applicable to other kinds of strain engineering in Z. mobilis.

A Review of the Scientific Rigor, Reproducibility, and Transparency Studies Conducted by the ABRF Research Groups

Shared research resource facilities, also known as core laboratories (Cores), are responsible for generating a significant and growing portion of the research data in academic biomedical research institutions. Cores represent a central repository for institutional knowledge management, with deep expertise in the strengths and limitations of technology and its applications. They inherently support transparency and scientific reproducibility by protecting against cognitive bias in research design and data analysis, and they have institutional responsibility for the conduct of research (research ethics, regulatory compliance, and financial accountability) performed in their Cores. The Association of Biomolecular Resource Facilities (ABRF) is a FASEB-member scientific society whose members are scientists and administrators that manage or support Cores. The ABRF Research Groups (RGs), representing expertise for an array of cutting-edge and established technology platforms, perform multicenter research studies to determine and communicate best practices and community-based standards. This review provides a summary of the contributions of the ABRF RGs to promote scientific rigor and reproducibility in Cores from the published literature, ABRF meetings, and ABRF RGs communications.

Metabolic Profiling of Glucose-Fed Metabolically Active Resting Zymomonas mobilis Strains

Zymomonas mobilis is the most efficient bacterial ethanol producer and its physiology is potentially applicable to industrial-scale bioethanol production. However, compared to other industrially important microorganisms, the Z. mobilis metabolome and adaptation to various nutritional and genetic perturbations have been poorly characterized. For rational metabolic engineering, it is essential to understand how central metabolism and intracellular redox balance are maintained in Z. mobilis under various conditions. In this study, we applied quantitative mass spectrometry-based metabolomics to explore how glucose-fed non-growing Z. mobilis Zm6 cells metabolically adapt to change of oxygen availability. Mutants partially impaired in ethanol synthesis (Zm6 adhB) or oxidative stress response (Zm6 cat) were also examined. Distinct patterns of adaptation of central metabolite pools due to the change in cultivation condition and between the mutants and Zm6 reference strain were observed. Decreased NADH/NAD ratio under aerobic incubation corresponded to higher concentrations of the phosphorylated glycolytic intermediates, in accordance with predictions of the kinetic model of Entner–Doudoroff pathway. The effects on the metabolite pools of aerobic to anaerobic transition were similar in the mutants, yet less pronounced. The present data on metabolic plasticity of non-growing Z. mobilis cells will facilitate the further metabolic engineering of the respective strains and their application as biocatalysts.

Peptides from Antarctic Krill ( Euphausia superba) Improve Osteoarthritis via Inhibiting HIF-2α-Mediated Death Receptor Apoptosis and Metabolism Regulation in Osteoarthritic Mice

Osteoarthritis (OA) is a prevalent debilitating disease which is predominantly characterized by cartilage degeneration. In the current study, destabilization of the medial meniscus (DMM) mouse model was used to investigate the effects of Antarctic krill peptides (AKP) on cartilage protection. As observed, AKP clearly ameliorate cartilage degeneration as evidenced by increased cartilage thickness and cartilage area and decreased histological Osteoarthritis Research Society International (OARSI) scores. Toluidine blue staining showed that AKO remarkably inhibited the loss of cartilage matrix in mice with OA. Hypoxia-inducible factor-2α (HIF-2α) has a key role in catabolic regulation and inflammation cascades which are the main causes of OA. AKP can down-regulate the expression of HIF-2α and its downstream genes such as MMP-13, Adamts-5, IL-1β, iNOS, CXCL-1, and NOS₂. Consistent with this, anabolic genes such as Acan and Col2α1 were restored after treatment with AKP. Chondrocyte apoptosis and the reduction in cartilage cell viability are also involved in the process of OA. The HIF-2α-mediated death receptor apoptosis signaling pathway has been involved in the regulation of chondrocyte apoptosis. AKP can reduce the expressions of key pro-apoptosis genes in Fas-FasL and DR3-DR3L signaling pathways such as Fas, FasL, FADD, caspase8, caspase3, DR3, DR3L, RIP, and NF-κB. In addition, expressions of antiapoptosis genes such as c-AIP and c-FLIP were increased significantly. These findings indicate that AKP can be used as a new functional factor in the development of functional foods and chondroprotective drugs.

Amino Acid Analysis by Hydrophilic Interaction Chromatography Coupled with Isotope Dilution Mass Spectrometry

Here, we describe an amino acid analysis that is based on the use of hydrophilic interaction liquid chromatography coupled with isotope dilution mass spectrometry for the accurate quantification of underivatized amino acids from hydrolyzed peptide/protein. Twelve underivatized amino acids were separated and detected during an 88-min runtime. The absolute limits of detection and limits of quantification (on column) of the four amino acids (isoleucine, phenylalanine, proline, and valine) were in the range of 6-80 and 20-200 fmol, respectively. As little as 25 pmol of peptide or protein hydrolysate is sufficient for determining absolute content.

The Reproduction Rate of Peptide Transporter PEPT-1 Deficient C. elegans Is Dependent on Dietary Glutamate Supply

Intestinal absorption of dietary amino acids is mediated via two routes. Free amino acids released by hydrolysis of dietary proteins are taken up by a multitude of amino acid transporters while di- and tripeptides released are taken up by the peptide transporter PEPT-1. Loss of PEPT-1 impairs growth, post-embryonic development and reproduction in Caenorhabditis elegans, and supplementation with a mixture of all L-amino acids only partially rescues fertility. In the present study, we demonstrate that dietary L-glutamate is the responsible amino acid that can increase fertility in hermaphrodite pept-1 worms. This effect was associated with a significantly higher uptake of glutamate/aspartate in pept-1 than in wildtype C. elegans. Furthermore, we found that the intestinal transporter proteins SNF-5 of the solute carrier SLC6 family of nutrient amino acid transporters (NAT) and AAT-6 of the SLC7 family as the light subunit of a heteromeric amino acid transporter (HAT) play a key role in glutamate homeostasis in pept-1 C. elegans. Genes encoding these transporters are highly expressed and upon silencing a 95% reduced fertility (snf-5) and sterility (aat-6) was observed. A subsequent L-glutamate supplementation failed to rescue these phenotypes. Dietary glutamate supplementation did neither influence the feeding frequency, nor did it improve mating efficiency of pept-1 males. Most strikingly, pept-1 were more prone to habituation to repeated gentle touch stimuli than wildtype C. elegans, and dietary glutamate supply was sufficient to alter this behavioral output by restoring the mechanosensory response to wildtype levels. Taken together, our data demonstrate a key role of L-glutamate in amino acid homeostasis in C. elegans lacking the peptide transporter in the intestine and demonstrate its distinct role in reproduction and for neural circuits mediating touch sensitivity.

Physicochemical characterization of porcine bone-derived grafting material and comparison with bovine xenografts for dental applications

Purpose

The physicochemical properties of a xenograft are very important because they strongly influence the bone regeneration capabilities of the graft material. Even though porcine xenografts have many advantages, only a few porcine xenografts are commercially available, and most of their physicochemical characteristics have yet to be reported. Thus, in this work we aimed to investigate the physicochemical characteristics of a porcine bone grafting material and compare them with those of 2 commercially available bovine xenografts to assess the potential of xenogenic porcine bone graft materials for dental applications.

Methods

We used various characterization techniques, such as scanning electron microscopy, the Brunauer-Emmett-Teller adsorption method, atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and others, to compare the physicochemical properties of xenografts of different origins.

Results

The porcine bone grafting material had relatively high porosity (78.4%) and a large average specific surface area (SSA; 69.9 m²/g), with high surface roughness (10-point average roughness, 4.47 µm) and sub-100-nm hydroxyapatite crystals on the surface. Moreover, this material presented a significant fraction of sub-100-nm pores, with negligible amounts of residual organic substances. Apart from some minor differences, the overall characteristics of the porcine bone grafting material were very similar to those of one of the bovine bone grafting material. However, many of these morphostructural properties were significantly different from the other bovine bone grafting material, which exhibited relatively smooth surface morphology with a porosity of 62.0% and an average SSA of 0.5 m²/g.

Conclusions

Considering that both bovine bone grafting materials have been successfully used in oral surgery applications in the last few decades, this work shows that the porcine-derived grafting material possesses most of the key physiochemical characteristics required for its application as a highly efficient xenograft material for bone replacement.

Isothiocyanyl Alanine as a Synthetic Intermediate for the Synthesis of Thioureayl Alanines and Subsequent Aminotetrazolyl Alanines

The synthesis of unnatural amino acids with small side-chain functionalities usable for further transformations is highly demanding for the expansion of the genetic code and other possible biotechnological applications. To this end, we wanted to report the utility of an unexplored unnatural amino acid, isothiocyanyl alanine (^NCSAla = Ita), for the synthesis of another class of unnatural amino acids, thioureayl alanines (^TUAla = Tua). The synthesis of a third class of unnatural amino acids, amino tetrazolyl alanines (^ATzAla = Ata), in a very good yield was subsequently achieved utilizing thioureayl alanines. Thus, a variety of aliphatic- and aromatic-substituted thioureayl alanines and aromatic-substituted amino tetrazolyl alanines were successfully synthesized in good to excellent yields. The photophysical properties of three of the fluorescent unnatural amino acids from two classes were also studied and presented herein.

Helleborus purpurascens-Amino Acid and Peptide Analysis Linked to the Chemical and Antiproliferative Properties of the Extracted Compounds

There is a strong drive worldwide to discover and exploit the therapeutic potential of a large variety of plants. In this work, an alcoholic extract of Helleborus purpurascens (family Ranunculaceae) was investigated for the identification of amino acids and peptides with putative antiproliferative effects. In our work, a separation strategy was developed using solvents of different polarity in order to obtain active compounds. Biochemical components were characterized through spectroscopic (mass spectroscopy) and chromatographic techniques (RP-HPLC and GC-MS). The biological activity of the obtained fractions was investigated in terms of their antiproliferative effects on HeLa cells. Through this study, we report an efficient separation of bioactive compounds (amino acids and peptides) from a plant extract dependent on solvent polarity, affording fractions with unaffected antiproliferative activities. Moreover, the two biologically tested fractions exerted a major antiproliferative effect, thereby suggesting potential anticancer therapeutic activity.

Zirconium silicate assisted removal of residual proteins after organic solvent deproteinization of human plasma, enhancing the stability of the LC-ESI-MS response for the bioanalysis of small molecules

An efficient blood plasma clean-up method was developed, where methanol protein precipitation was applied, followed by zirconium silicate assisted exclusion of residual proteins. A strong binding of zirconium (IV) silicate to the proteins enabled the elimination of remaining proteins after solvent deproteinization through a rapid solid-phase extraction (SPE) procedure. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF MS) was used for monitoring the proteins during clean-up practice applied to human plasma samples. The proteins were quantified by colorimetric detection using the bicinchoninic acid (BCA) assay. The presented analytical strategy resulted in the depletion of >99.6% proteins from human plasma samples. Furthermore, high-performance liquid chromatography hyphenated to diode-array and electrospray ionization mass spectrometric detection (HPLC-DAD/ESI MS) was applied for qualitative and quantitative analysis of the caffeoylquinic acids (CQAs) and their metabolites in human plasma. The procedure demonstrated high recoveries for the standard compounds spiked at different concentrations. Cynarin and chlorogenic acid were recovered in the range of 81-86% and 78-83%, respectively. Caffeic acid was extracted in the excess of 89-92%, while ferulic acid and dihydroxyhydrocinnamic acid showed a recovery of 87-91% and 92-95%, respectively. The method was partially validated in accordance with FDA-Industry Guidelines for Bioanalytical Method Validation (2001). The presented scheme improves the clean-up efficacy of the methanol deproteinization, significantly reduces the matrix effects and provides a great analytical tool for the isolation of small molecules from human plasma.

Effect of cooking on meat proteins: mapping hydrothermal protein modification as a potential indicator of bioavailability

Thermal treatment of meat proteins induces a range of observable and molecular-level changes. In order to understand and track these heat-induced modifications at the amino acid level, various analytical techniques were used. Changes were observed both in the soluble and in the insoluble fractions after hydrothermal treatment of minced beef samples. Redox proteomics clearly indicated increasing oxidative modification of proteins with increased heat exposure. Collagens in the soluble fraction and myosin in the insoluble fraction were found to be highly susceptible to such modifications. Maillard reaction products in the insoluble and pyrrolidone formation in the soluble fraction steadily increased with increased heat exposure. Fluorescence studies indicated a rapid increase in fluorescence with heat, suggesting the formation of advanced glycation end products. Overall these results provide a deeper understanding of the effect of cooking on meat proteins and the possible relationship to processing conditions in meat-derived food.

Hypolipidemic effect of dietary water-soluble protein extract from chicken: impact on genes regulating hepatic lipid and bile acid metabolism

BACKGROUND

Amount and type of dietary protein have been shown to influence blood lipids. The present study aimed to evaluate the effects of a water-soluble fraction of chicken protein (CP) on plasma and hepatic lipid metabolism in normolipidemic rats.

METHODS

Male Wistar rats were fed either a control diet with 20 % w/w casein as the protein source, or an experimental diet where casein was replaced with CP at 6, 14, or 20 % w/w for 4 weeks.

RESULTS

Rats fed CP had markedly reduced levels of triacylglycerols (TAG) and cholesterol in both plasma and liver, accompanied by stimulated hepatic mitochondrial fatty acid oxidation and carnitine palmitoyltransferase 2 activity in the 20 % CP group compared to the control group. In addition, reduced activities and gene expression of hepatic enzymes involved in lipogenesis were observed. The gene expression of sterol regulatory element-binding transcription factor 1 was reduced in the 20 % CP-fed rats, whereas gene expression of peroxisome proliferator-activated receptor alpha was increased. Moreover, 6, 14, and 20 % CP-fed rats had significantly increased free carnitine and acylcarnitine plasma levels compared to control rats. The plasma methionine/glycine and lysine/arginine ratios were reduced in 20 % CP-treated rats. The mRNA level of ATP-binding cassette 4 was increased in the 20 % CP group, accompanied by the increased level of plasma bile acids.

CONCLUSIONS

The present data suggest that the hypotriglyceridemic property of a water-soluble fraction of CP is primarily due to effects on TAG synthesis and mitochondrial fatty acid oxidation. The cholesterol-lowering effect by CP may be linked to increased bile acid formation.

A fish protein hydrolysate alters fatty acid composition in liver and adipose tissue and increases plasma carnitine levels in a mouse model of chronic inflammation

Background

There is growing evidence that fish protein hydrolysate (FPH) diets affect mitochondrial fatty acid metabolism in animals. The aim of the study was to determine if FPH could influence fatty acid metabolism and inflammation in transgene mice expressing human tumor necrosis factor alpha (hTNFα).

Methods

hTNFα mice (C57BL/6 hTNFα) were given a high-fat (23%, w/w) diet containing 20% casein (control group) or 15% FPH and 5% casein (FPH group) for two weeks. After an overnight fast, blood, adipose tissue, and liver samples were collected. Gene expression and enzyme activity was analysed in liver, fatty acid composition was analyzed in liver and ovarian white adipose tissue, and inflammatory parameters, carnitine, and acylcarnitines were analyzed in plasma.

Results

The n-3/n-6 fatty acid ratio was higher in mice fed the FPH diet than in mice fed the control diet in both adipose tissue and liver, and the FPH diet affected the gene expression of ∆6 and ∆9 desaturases. Mice fed this diet also demonstrated lower hepatic activity of fatty acid synthase. Concomitantly, a lower plasma INF-γ level was observed. Plasma carnitine and the carnitine precursor γ-butyrobetaine was higher in the FPH-group compared to control, as was plasma short-chained and medium-chained acylcarnitine esters. The higher level of plasma acetylcarnitine may reflect a stimulated mitochondrial and peroxisomal β-oxidation of fatty acids, as the hepatic activities of peroxisomal acyl-CoA oxidase 1 and mitochondrial carnitine palmitoyltransferase-II were higher in the FPH-fed mice.

Conclusions

The FPH diet was shown to influence hepatic fatty acid metabolism and fatty acid composition. This indicates that effects on fatty acid metabolism are important for the bioactivity of protein hydrolysates of marine origin.

Bioanalytical LC separation techniques for quantitative analysis of free amino acids in human plasma

The quantitative analysis of free amino acids in human plasma has become an important and essential analysis parameter in different areas of life sciences. Free amino acid concentrations in human plasma samples are generally determined by means of GC or LC after chemical derivatization followed by UV, fluorescent or MS detection of the amino acid derivatives. Derivatization of free amino acids is done either pre- or post-column, and the amino acid derivatives obtained posess improved chromatographic behavior, increased detection sensitivity and selectivity compared with non-derivatized free amino acids. This work gives an overview of different chemical derivatization methods applied and their liquid separation techniques in bioanalytical assays for quantitative free amino acid analysis in human plasma samples. Important plasma preparation procedures, pre- and post-column derivatization, and different LC separation techniques are presented.

Determination of the tolerable upper intake level of leucine in acute dietary studies in young men

BACKGROUND

Leucine has been suggested to improve athletic performance. Therefore, the branched-chain amino acids (BCAAs), especially leucine, are popular as dietary supplements in strength-training athletes; however, the intake of leucine in excess of requirements raises concerns regarding adverse effects. Currently, the tolerable upper intake level (UL) for leucine is unknown.

OBJECTIVE

The objective of the current study was to determine the UL for leucine in adult men under acute dietary conditions.

DESIGN

Five healthy adults (20-35 y) each received graded stepwise increases in leucine intakes of 50, 150, 250, 500, 750, 1000, and 1250 mg · kg⁻¹ · d⁻¹, which corresponded to the Estimated Average Requirement (EAR) and the EAR ×3, ×5, ×10, ×15, ×20, and ×25 in a total of 29 studies. The UL of leucine was identified by the measurement of plasma and urinary biochemical variables and changes in leucine oxidation by using l-[1-¹³C]-leucine.

RESULTS

A significant increase in blood ammonia concentrations above normal values, plasma leucine concentrations, and urinary leucine excretion were observed with leucine intakes >500 mg · kg⁻¹ · d⁻¹. The oxidation of l-[1-¹³C]-leucine expressed as label tracer oxidation in breath (F¹³CO₂), leucine oxidation, and α-ketoisocaproic acid (KIC) oxidation led to different results: a plateau in F¹³CO₂ observed after 500 mg · kg⁻¹ · d⁻¹, no clear plateau observed in leucine oxidation, and KIC oxidation appearing to plateau after 750 mg · kg⁻¹ · d⁻¹.

CONCLUSION

On the basis of plasma and urinary variables, the UL for leucine in healthy adult men can be suggested at 500 mg · kg⁻¹ · d⁻¹ or ~35 g/d as a cautious estimate under acute dietary conditions.

Amino acid analysis by hydrophilic interaction chromatography coupled with isotope dilution mass spectrometry

Here, we describe an amino acid analysis that is based on the use of hydrophilic interaction liquid chromatography coupled with isotope dilution mass spectrometry for the accurate quantification of underivatized amino acids from hydrolyzed peptide/protein. Twelve underivatized amino acids were separated and detected during an 88-min runtime. The absolute limits of detection and limits of quantification (on column) of the four amino acids (isoleucine, phenylalanine, proline, and valine) were in the range of 6-80 and 20-200 fmol, respectively. As little as 25 pmol of peptide or protein hydrolysates is sufficient for determining absolute content.

RP-LC of phenylthiocarbamyl amino acid adducts in plasma acetonitrile extracts: use of multiple internal standards and variable wavelength UV detection

The measurement of physiological amino acids in body fluids and circulating cells can be relevant in the search for biological correlates of neuropsychiatric, neurological, body weight, and pain diseases. Several techniques are available for the quantitative analysis of free amino acids, including UV detection after precolumn derivatization. These systems have low specificity due to possible interferences at the analytical wavelength. Another problem linked to these methods is variations potentially occurring during extraction, derivatization, and chromatography of amino acids in biological matrices. We present here a modified reversed-phase LC of phenylthiocarbamyl amino acids in plasma deproteinated by the organic solvent acetonitrile. Specificity was monitored by UV-photodiode array detection and accuracy was controlled by a plasma spiking procedure with three internal standards. A dual-wavelength spectrophotometry (254, 283 nm) was used to quantify coeluting ornithine and tryptophan adducts. The method is simple and economical and enables the measure of most plasma amino acids for clinical research, also during therapeutic drug monitoring. Dual UV-fluorimetric detection solutions can improve its sensitivity.

Ornithine phenylacetate prevents disturbances of motor-evoked potentials induced by intestinal blood in rats with portacaval anastomosis

BACKGROUND & AIMS

Ornithine phenylacetate (OP) is a new drug that has been proposed for the treatment of hepatic encephalopathy (HE) because it decreases plasma ammonia. We performed a study to assess if OP would impact on neuronal function.

METHODS

Motor-evoked potentials (MEP), a surrogate of hepatic encephalopathy, were assessed (without anesthesia) in rats with portacaval anastomosis (PCA) that received gastrointestinal blood (GIB). Rats were pre-treated with OP prior to GIB. Ammonia and related metabolites (plasma, urine, and brain microdialysis) were assessed by HPLC and mass spectroscopy.

RESULTS

OP (one dose or 3 days) prevented disturbances in MEP induced by GIB in PCA rats. In rats treated with OP for 3 days, the amplitude and latency of MEP remained stable (-1% and +1%), while in the control group the amplitude decreased -21% and the latency increased +12% (p<0.01). OP attenuated the rise of ammonia in plasma by 45%, ammonia in brain microdialysate by 48%, induced a faster glutamine rise and the appearance of phenylacetylglutamine in plasma and urine. In addition, OP was associated with a lower concentration of ammonia and glutamate in brain microdialysate (approx. 50%).

CONCLUSIONS

OP prevents abnormalities in MEP precipitated by GIB in a model of HE. This is probably due to the enhancement of glutamine synthesis and metabolism, which results in a lower rise of plasma ammonia and the prevention of changes in glutamate in microdialysate. Thus, OP may be a good drug to prevent HE precipitated by gastrointestinal bleeding.

Optimization and control of perfusion cultures using a viable cell probe and cell specific perfusion rates

Consistent perfusion culture production requires reliable cell retention and control of feed rates. An on-line cell probe based on capacitance was used to assay viable biomass concentrations. A constant cell specific perfusion rate controlled medium feed rates with a bioreactor cell concentration of approximately 5 x 10(6) cells mL(-1). Perfusion feeding was automatically adjusted based on the cell concentration signal from the on-line biomass sensor. Cell specific perfusion rates were varied over a range of 0.05 to 0.4 nL cell(-1) day(-1). Pseudo-steady-state bioreactor indices (concentrations, cellular rates and yields) were correlated to cell specific perfusion rates investigated to maximize recombinant protein production from a Chinese hamster ovary cell line. The tissue-type plasminogen activator concentration was maximized ( approximately 40 mg L(-1)) at 0.2 nL cell(-1) day(-1). The volumetric protein productivity ( approximately 60 mg L(-1) day(-1) was maximized above 0.3 nL cell(-1) day(-1). The use of cell specific perfusion rates provided a straightforward basis for controlling, modeling and optimizing perfusion cultures.

A protein tyrosine phosphatase 1B activity inhibitor from the fruiting bodies of Ganoderma lucidum (Fr.) Karst and its hypoglycemic potency on streptozotocin-induced type 2 diabetic mice

Inhibition of protein tyrosine phosphatase 1B (PTP1B) activity has been considered to be a promising therapy approach to treat type 2 diabetes. In this work, a novel PTP1B activity inhibitor, named FYGL (Fudan-Yueyang-G. lucidum), was screened from the fruiting bodies of Ganoderma lucidum and showed an efficient PTP1B inhibitory potency with IC₅₀ = 5.12 ± 0.05 μg/mL. FYGL is a water-soluble macromolecular proteoglycan with a protein to polysaccharide ratio of 17:77 and a viscosity-average molecular weight (M(η)) of 2.6 × 10⁵. The type 2 diabetic mice treated orally by FYGL showed an obvious decrease in plasma glucose level compared with the diabetic controls without drug treatment, comparable with that of diabetic mice treated with metformin, a clinical drug. The toxicity of FYGL is very low. The results indicate that FYGL may serve as a drug candidate or a health-care food for diabetic therapy or protection.

Anti-HIV-1 activity of salivary MUC5B and MUC7 mucins from HIV patients with different CD4 counts

BACKGROUND

We have previously shown that MUC5B and MUC7 mucins from saliva of HIV negative individuals inhibit HIV-1 activity by 100% in an in vitro assay. The purpose of this subsequent study was to investigate whether MUC5B and MUC7 from saliva of HIV patients or with full blown AIDS had a similar inhibitory activity against the virus.

METHODS

Salivary MUC5B and MUC7 from HIV patients with different CD4 counts (< 200, 200-400 and > 400) were incubated with HIV-1 prior to infection of the human T lymphoblastoid cell line (CEM SS cells). Cells were then cultured and viral replication was measured by a qualitative p24 antigen assay. The size, charge and immunoreactivity of mucins from HIV negative and positive individuals was also analysed by SDS-PAGE, Western blot and ELISA respectively.

RESULTS

It was shown that irrespective of their CD4 counts both MUC5B and MUC7 from HIV patients, unlike the MUC5B and MUC7 from HIV negative individuals, did not inhibit HIV-1 activity. Size, charge and immunoreactivity differences between the mucins from HIV negative and positive individuals and among the mucins from HIV patients of different CD4 count was observed by SDS-PAGE, Western blot and ELISA.

CONCLUSIONS

Purified salivary mucins from HIV positive patients do not inhibit the AIDS virus in an in vitro assay. Although the reason for the inability of mucins from infected individuals to inhibit the virus is not known, it is likely that there is an alteration of the glycosylation pattern, and therefore of charge of mucin, in HIV positive patients. The ability to inhibit the virus by aggregation by sugar chains is thus diminished.

Multicentre age-related reference intervals for cerebrospinal fluid serine concentrations: implications for the diagnosis and follow-up of serine biosynthesis disorders

The disorders of serine biosynthesis are a group of inborn errors of metabolism characterised by congenital microcephaly, seizures and severe psychomotor retardation. Although these disorders are rare the prompt recognition of serine deficiency is important as these disorders are treatable. The diagnosis is based on decreased concentrations of serine in cerebrospinal fluid (CSF). It has previously been reported that CSF serine concentrations are inversely associated with age. However, accurate age-related reference intervals have not been generated which has contributed to cases not being identified. In a multicentre study involving 9 different laboratories a total of 424 CSF serine results were obtained. Regression based analyses were performed to calculate age-specific reference intervals. Lower reference intervals for subjects aged 1week, 1month, 6months, 1year, 3years and 15years were 35.0, 31.0, 26.0, 24.0, 21.0 and 17.0μmol/L respectively. Assessment of CSF serine concentrations in 11 patients (aged 1day to 13years) previously diagnosed with disorders of serine biosynthesis (serine concentrations ranging from 5 to 18μmol/L) were clearly decreased compared to our age-related reference intervals and would have correctly identified all cases, thus enabling prompt treatment. However, if age had not been taken into consideration a reference interval of 12.6-69.4μmol/L would be obtained for the combined data set and would have resulted in 2 cases being missed. In conclusion, appropriate age-related reference intervals for CSF serine should be used to diagnose patients with inborn errors of serine biosynthesis.

Automated precolumn derivatization system for analyzing physiological amino acids by liquid chromatography/mass spectrometry

An automated method for high-throughput amino acid analysis, using precolumn derivatization high-performance liquid chromatography/electrospray mass spectrometry (HPLC/ESI-MS), was developed and evaluated. The precolumn derivatization step was performed in the reaction port of a home-built auto-sampler system. Amino acids were derivatized with 3-aminopyridyl-N-hydroxysuccinimidyl carbamate, and a 3 microm Wakosil-II 3C8-100HG column (100 x 2.1 mm i.d.) was used for separation. To achieve a 13 min cycle for each sample, the derivatization and separation steps were performed in parallel. The results of the method evaluation, including the linearity, and the intra- and inter-precision, were sufficient to measure physiological amino acids in human plasma samples. The relative standard deviations of typical amino acids in actual human plasma samples were below 10%.