Development of a self-reinforced starch-derived film with biocompatibility and mechanical properties

The scraps produced while processing packaging materials will cause a waste of resources. In this study, starch-based self-reinforced film (SSRF) using thermoplastic starch (TPS, 45 wt%) and polypropylene (PP, 53 wt%) was developed. The effect of extrusion times (1-4 times) on the film structure and performance was explored. The results show as the number of extrusions increases, the color of SSRF deepens from gray-white to brown, and the crystallinity increases. The mechanical properties of the four types of SSRF first increase and then decrease. The 2-SSRF has the best performance, with tensile strength of 13.23 MPa, elongation at break of 61.35%, Young's modulus of 1128.99 MPa, and flexural strength of 33.19 MPa. Proper extrusion improves the compatibility of TPS and PP. However, repeated extrusion will cause PP degradation and TPS carbonization, reducing interfacial interaction. This study developed new starch-based self-reinforced film and provided theoretical guidance for reusing packaging material scraps.

Extraction of naturally occurring peptides versus the tryptic digestion of proteins from fetal versus adult bovine serum for LC-ESI-MS/MS

The naturally occurring peptides and digested proteins of fetal versus adult bovine serum were compared by LC-ESI-MS/MS after correction against noise from blank injections and random MS/MS spectra as statistical controls. Serum peptides were extracted by differential precipitation with mixtures of acetonitrile and water. Serum proteins were separated by partition chromatography over quaternary amine resin followed by tryptic digestion. The rigorous X!TANDEM goodness of fit algorithm that has a low error rate as demonstrated by low FDR q-values (q ≤ 0.01) showed qualitative and quantitative agreement with the SEQUEST cross correlation algorithm on 12,052 protein gene symbols. Tryptic digestion provided a quantitative identification of the serum proteins where observation frequency reflected known high abundance. In contrast, the naturally occurring peptides reflected the cleavage of common serum proteins such as C4A, C3, FGB, HPX, A2M but also proteins in lower concentration such as F13A1, IK, collagens and protocadherins. Proteins associated with cellular growth and development such as actins (ACT), ribosomal proteins like Ribosomal protein S6 (RPS6), synthetic enzymes and extracellular matrix factors were enriched in fetal calf serum. In contrast to the large literature from cord blood, IgG light chains were absent from fetal serum as observed by LC-ESI-MS/MS and confirmed by ELISA.

[Clinical characteristics and prognosis of five children with maturity onset of diabetes of the young 12 subtype]

Objective: To analyze the genetic and clinical characteristics, treatment and prognosis of patients diagnosed with maturity onset of diabetes of the young (MODY) 12 subtype. Methods: This retrospective study collected and analyzed data from 5 children with MODY12 subtype caused by ABCC8 gene variants who underwent inpatient and outpatient genetic testing at Beijing Children's Hospital from January 2016 to December 2023. Their clinical and genetic features, treatment, and follow-up results were analyzed. Results: Among the 5 patients with MODY12 subtype, 4 were male and 1 was female, with an age of 13.4 (5.5, 14.6) years. Four of the patients were born large for gestational age, while one was born small for gestational age. Two patients were overweight or obese. Three patients exhibited typical symptoms of diabetes, while 2 were incidentally found to have elevated blood glucose level. One patient was found to have diabetic ketoacidosis at onset, who was diagnosed with congenital hyperinsulinism during the neonatal period and received diazoxide treatment, and experienced intellectual developmental delay. All 5 patients had autosomal dominant inherited diabetes within 3 generations. The fasting blood glucose at onset was 7.5 (6.5, 10.0) mmol/L, the haemoglobin, A1c (HbA1c) was 11.8% (7.5%, 13.5%), and the fasting C-peptide was 1.2 (1.1, 2.2)μg/L. The duration of follow-up was 15 (9, 32) months. One patient underwent lifestyle intervention, two received metformin orally, one received insulin therapy, and the other received subcutaneous injection of insulin combined with sulfonylurea orally. At the last follow-up, the median fasting blood glucose was 6.1 (5.1, 7.0) mmol/L, the HbA1c was 5.9% (5.7%, 7.1%), and the fasting C-peptide was 1.7 (0.9, 2.9)μg/L. One patient developed diabetic retinopathy. There were 4 missense variations in ABCC8 gene and one in-frame deletion, all of which were maternally inherited heterozygotes. Conclusions: MODY12 subtype is a heterogeneous disorder with the age of onset from infancy to adolescence. It can present as mild hyperglycemia or diabetic ketoacidosis, and has a high incidence of obesity. Definitive diagnosis can be achieved through genetic test, and individualized treatment is recommended based on glucose levels.

Characterizations and film-forming properties of different fractionated high-amylose maize starches subjected to hydroxypropylation

Dual-modifications of jet milling and hydroxypropylation were used to improve the functional properties of maize starch (HM, containing 67 % amylose). The fractions obtained in three sizes (HM-S, HM-M, HM-L) were further treated with 10 % and 30 % propylene oxide (PO10 and PO30). The infrared peak of starch at 2794 cm-1 indicated the successful introduction of hydroxypropyl groups. The molar degree of substitution (MS) increased with the degree of jet milling. The MS of HM-L-PO10 is 0.4, that of HM-M-PO10 is 0.7, and that of HM-S-PO10 is 0.9. The crystallinity of dual-modified HM increased, but the crystal type remained unchanged, still being B-type. Dual-modification significantly improved the performance of starch, and the higher the degree of modification, the better the optimization effect. The lowest enthalpy changes of gelatinization (ΔH = 3.49 J/g), the best freeze-thaw stability, the highest elongation at break (110.42 %) and transmittance (81.22 %) were shown in HM-S-PO30. The present study confirms that HM-S-PO30 films have the best physicochemical and mechanical properties, which provide new insights into optimizing starch-based packaging materials.

Unveiling structure and performance of tea-derived cellulose nanocrystals

In this study, cellulose was extracted from black tea residues to produce black tea cellulose nanocrystals (BT-CNCs) using an optimized acid hydrolysis method. The structure and performance of BT-CNCs were evaluated. The results showed that the optimal conditions for acidolysis of BT-CNCs included a sulfuric acid concentration of 64 %, a solid-liquid ratio of 1:18 (w/v), a hydrolysis temperature of 45 °C, and a hydrolysis time of 50 min. The optimization process resulted in a 44.8 % increase in the yield of BT-CNCs, which exhibited a crystallinity of 68.57 % and were characterized by the typical cellulose I structure. The diameters of the particles range from 5 to 45 nm, and they exhibit aggregation behavior. Notably, BT-CNCs demonstrated excellent storage stability, and the Tyndall effect occurred when exposed to a single beam of light. Although the thermal stability of BT-CNCs decreased, their primary thermal degradation temperature remained above 200 °C. The colloidal nature of BT-CNCs was identified as a non-Newtonian fluid with "shear thinning" behavior. This study introduces a novel method to convert tea waste into BT-CNCs, increasing the yield of BT-CNCs and enhancing waste utilization. BT-CNCs hold promise for application in reinforced composites, offering substantial industrial value.

Rational design to improve the catalytic efficiency and stability of arginine deiminase

Arginine deiminase (ADI) has garnered significant interest because of its ability to objectively eradicate cancer cells and produce L-citrulline. To meet the production demands, this study focused on enhancing the enzyme activity and thermal stability of ADI. In this study, 24 ADI mutants were obtained through computer aid site-specific mutation in the ADI of Enterobacter faecalis. Notably, the specific enzyme activities of F44W, N163P, E220I, E220L, N318E, A336G, T340I, and N382F increased, reaching 1.33-2.53 times that of the original enzyme. This study confirmed that site-specific mutations are critical for optimizing enzyme function. Additionally, the F44W, N163P, E220I, T340I, and A336G mutants demonstrated good thermal stability. The optimal pH for mutant F44W increased to 8, whereas mutants E220I, I244V, A336G, T340I, and N328F maintained an optimal pH of 7.5. Conversely, the M109L, N163P, E220L, I244L, and N318E mutants shad an optimal pH of 7. This study revealed that mutant enzymes with increased activity were more likely to contain mutation sites situated near the four loops associated with catalytic residues, whereas mutations at the dimer junction sites had a higher tendency to enhance enzyme stability. These findings contribute to the development of ADI industrial applications and its modifications.

Starch-based biodegradable composites: Effects of in-situ re-extrusion on structure and performance

In this study, starch-based biodegradable composites (SDC) were prepared by extruding using thermoplastic starch (TPS, 65%wt), polylactic acid (PLA, 30%wt) and poly (butylene adipate co-terephthalate) (PBAT, 5%wt). Structure and properties of the SDC were compared by performing 1-, 2-, 3-times extrusion. The results show that in-situ re-extrusion refines the TPS in composites and reduces the size of the phase. As the number of extrusions increases, the ester bond of composites at 868 cm-1 disappears, the crystallinity increases, and the thermal stability decreases. Among the three types of composites, the mechanical properties and hydrophobic properties of the material obtained by the 2-times are the most outstanding. Compared with SDC, the elongation at break and Young's modulus of SDC-2 are significantly increased, with an increase of 8.01 % and 1.28 % in the machine direction and an increase of 11.02 % and 1.79 % in the transverse direction respectively. Additionally, water contact angle range of SDC-2 from 98.7° to 101.7°. Therefore, SDC prepared by 2-times in-situ re-extrusion has the best film properties and is an ideal packaging material. This study presents a novel method for fabricating starch-degradable composite films by in-situ re-extrusion, providing new insights into the development of starch packaging materials.

Structure and functional characteristics of starch from different hulled oats cultivated in China

This work aimed to evaluate the structure and functional characteristics of starch from ten hulled oat cultivars grown in different locations in China. The protein, phosphorus, amylose, and starch contents were 0.2-0.4 %, 475.7-691.8 ppm, 16.2-23.0 %, and 93.6-96.7 %, respectively. All the starches showed irregular polygonal shapes and A-type crystallization with molecular weights ranging from 7.2 × 107 to 4.5 × 108 g/mol. The amounts of amylopectin A (DP 6-12), B1 (DP 13-24), B2 (DP 25-36), and B3 (DP > 36) chains were in the ranges of 10.3-16.0 %, 54.5-64.8 %, 16.5-21.1 %, and 4.9-13.1 %, respectively. The starches differed significantly in gelatinization temperatures, pasting viscosity, solubility, swelling power, rheological properties, and digestion parameters. The results revealed that the larger particle size could increase the peak viscosity of the starch paste. The presence of phosphorus increased the gelatinization temperature and enhanced the resistant starch content. The starch granules with higher crystallinity contained a higher proportion of phosphate, which increased final viscosity and setback viscosity but decreased rapidly digestible starch. Overall, oat starch with a high phosphorus content could be used to prepare low-glycemic-index food for diabetes patients.

Metabolic Engineering of Escherichia coli for High-Titer Biosynthesis of 3'-Sialyllactose

3'-Sialyllactose (3'-SL) is among the foremost and simplest sialylated breast milk oligosaccharides. In this study, an engineered Escherichia coli for high-titer 3'-SL biosynthesis was developed by introducing a multilevel metabolic engineering strategy, including (1) the introduction of precursor CMP-Neu5Ac synthesis pathway and high-performance α2,3-sialyltransferase (α2,3-SiaT) genes into strain BZ to achieve de novo synthesis of 3'-SL; (2) optimizing the expression of glmS-glmM-glmU involved in the UDP-GlcNAc and CMP-Neu5Ac synthesis pathways, and constructing a glutamine cycle system, balancing the precursor pools; (3) analysis of critical intermediates and inactivation of competitive pathway genes to redirect carbon flux to 3'-SL biosynthesis; and (4) enhanced catalytic performance of rate-limiting enzyme α2,3-SiaT by RBS screening, protein tag cloning. The final strain BZAPKA14 yielded 9.04 g/L 3'-SL in a shake flask. In a 3 L bioreactor, fed-batch fermentation generated 44.2 g/L 3'-SL, with an overall yield and lactose conversion of 0.53 g/(L h) and 0.55 mol 3'-SL/mol, respectively.

Minced Beef Meat Paste Characteristics: Gel Properties, Water Distribution, and Microstructures Regulated by Medium Molecular Mass of γ-Poly-Glutamic Acid

The influences of various m-γ-PGA (0.08-0.20%, w/w) concentrations on the properties of minced beef meat paste in terms of rheological properties, texture, moisture distribution, and microstructures were evaluated. The results indicated that m-γ-PGA enhanced the water-holding capacity, gel strength, texture, and whiteness of the minced beef meat paste. Based on the microstructural results, m-γ-PGA helped form a more organized and compact gel, thereby limiting the migration of water through the gel matrix. In contrast to the control group, the water-holding property, gel strength, and whiteness of minced meat paste gels with m-γ-PGA content of 0.12% increased from 75.89%, 584.51 g·cm, and 61.83 to 79.91%, 780.87 g·cm, and 62.54, respectively (p < 0.05), exhibiting the highest water-holding property and gel strength. Thus, m-γ-PGA exhibits great potential for minced meat paste products as a healthy gel water retainer and enhancer in low-fat meat products.

Semi-rationally designed site-saturation mutation of Helicobacter pylori α-1,2-fucosyltransferase for improved catalytic activity and thermostability

Helicobacter pylori HpfutC, a glycosyltransferase (GT) 11 family glycoprotein, has great potential for industrial 2'-fucosyllactose (2'-FL) production. However, its limited catalytic activity, low expression, and poor thermostability hinder practical applications. Herein, a semi-rationally designed site-saturation mutation was applied to engineer the catalytic activity and thermostability of HpfutC. The 6 single point mutants (K102T, R105C, D115S, Y251F, A255G and K282E) and 6 combined mutants (V1, V2, V3, V4, V5, and V6) with enhanced enzyme activity were obtained by mutant library screening and ordered recombination mutation. The optimal mutant V6, with an optimum temperature of 40 °C, was not a metal-dependent enzyme, yet the reaction was facilitated by Mn2+. Compared to wild-type HpfutC, mutant V6 exhibited a 2.3-fold increase in specific activity and a 2.18-fold increase in half-life at 40 °C, respectively. Kinetic parameters indicated that the Km values of mutant V6 were 34.5 % (lactose) and 25.0 % (GDP-L-fucose) lower than those of the wild enzyme, whereas the kcat/Km values were 1.20 and 1.25-fold higher than those of the wild enzyme. Further, 3D-structure analysis revealed that the highly rigid structure, formation of new hydrogen bonds, increased hydrophobic residues and redistribution of electrostatic charges on the surface may be responsible for the elevated enzyme activity and thermostability. The strategy adopted in this study is of great significance to the solution of the technical bottleneck of HpfutC and the industrial application of 2'-FL.

Zmhdz9, an HD-Zip transcription factor, promotes drought stress resistance in maize by modulating ABA and lignin accumulation

Maize is the largest crop in the world in terms of both planting area and total yield, and it plays a crucial role in ensuring global food and feed security. However, in recent years, with climate deterioration, environmental changes, and the scarcity of freshwater resources, drought has become a serious limiting factor for maize yield and quality. Drought stress-induced signals undergo a series of transmission processes to regulate the expression of specific genes, thereby affecting the drought tolerance of plants at the tissue, cellular, physiological and biochemical levels. Therefore, in this study we investigated the HD-Zip transcription factor gene Zmhdz9, and yeast activation experiments demonstrated that Zmhdz9 exhibited transcriptional activation activity. Under drought stress, high abscisic acid (ABA) and lignin levels significantly improved drought resistance in maize. Yeast two-hybrid, bimolecular fluorescence complementation (BIFC) and pull-down experiments showed that Zmhdz9 interacted with ZmWRKY120 and ZmTCP9, respectively. Overexpression of Zmhdz9 and gene editing of ZmWRKY120 or ZmTCP9 improved maize drought resistance, indicating their importance in the drought stress response. Furthermore, Zmhdz9 promoted the direct transcription of ZmWRKY120 in the W-box, activating elements of the ZmNCED1 promoter, which encodes a key enzyme in ABA biosynthesis. Additionally, Zmhdz9 promoted direct transcription of ZmTCP9 in the GGTCA motif, activating elements of the ZmKNOX8 promoter, which encodes a key enzyme in lignin synthesis. This study showed that the regulation of ABA and lignin by Zmhdz9 is essential for drought stress resistance in maize.

SERS and MRS signals engineered dual-mode aptasensor for simultaneous distinguishment of aflatoxin subtypes

The accurate monitoring of aflatoxin subtypes is vitally important for food safety. Herein, a dual-mode aptasensor with surface-enhanced Raman scattering (SERS) and magnetic relaxation switching (MRS) signals is developed for the detection of aflatoxin B1, B2 and M1 (i.e. AFB1, AFB2 and AFM1). Au-Ag Janus NPs and Au-mushroom NPs are prepared and show intense and non-interfering SERS peaks without the additional modification of Raman molecules, and are utilized as SERS nanotags for the distinguishment of AFB1 and AFB2. Fe3O4@Au NPs functionalized by AFM1 aptamers are applied as MRS nanoprobes for the monitoring of AFM1. Aptamers engineered SERS nanotags and MRS nanoprobes are assembled, and show strong SERS performances and high transverse relaxation time (T2). AFB1, AFB2 and AFM1 induce the separation of SERS nanotags from the assemblies and the dispersion of Fe3O4@Au NPs, resulting in the decrease of SERS signals at 1278 cm-1 and 1000 cm-1 as well as the reduction of T2 values. The dual-mode but three kinds of detection signals don't interfere with each other and exhibit a significant linear relationship with the concentration of targets. This platform provides a high throughput monitoring strategy for the simultaneous analysis of different subtypes of mycotoxin.

Expectations for employing Escherichia coli Nissle 1917 in food science and nutrition

As a promising probiotic strain, Escherichia coli Nissle 1917 (EcN) has been demonstrated to confer beneficial effects on intestinal health, immune function, and pathogen prevention. Additionally, EcN has also been widely studied due to its clear genomic information, tractable gene regulation, and simple growth conditions. This review summarizes the various applications potential of EcN in food science and nutrition, including inflammation prevention, tumor-targeting therapy, antibacterial agents for food, and nutrient production with a focus on specific case studies. Moreover, we highlight the major challenges of employing EcN in food science and nutrition, including regulatory approval, stability during food processing, and consumer acceptance. Finally, we conclude with a discussion on perspectives related to employing EcN in food science and nutrition.

Human milk oligosaccharide lacto-N-tetraose: Physiological functions and synthesis methods

Human milk oligosaccharides (HMOs) have attracted considerable attention due to their unique role in boosting infant health. Among the HMOs, lacto-N-tetraose (LNT) is a significant constituent associated with various health benefits, such as prebiotic effects, antiadhesive antimicrobials, antiviral protection, and immune modulators. LNT has received a "Generally Recognized as Safe" status by the American Food and Drug Administration and was approved as a food ingredient for infant formula. However, the limited availability of LNT poses a major challenge for its application in food and medicine. In this review, we first explored the physiological functions of LNT. Next, we describe several synthesis methods for production of LNT, including chemical, enzymatic, and cell factory approaches, and summarize the pivotal research results. Finally, challenges and opportunities for the large-scale synthesis of LNT were discussed.

Advanced dendritic glucan-derived biomaterials: From molecular structure to versatile applications

There is considerable interest in the development of advanced biomaterials with improved or novel functionality for diversified applications. Dendritic glucans, such as phytoglycogen and glycogen, are abundant biomaterials with highly branched three-dimensional globular architectures, which endow them with unique structural and functional attributes, including small size, large specific surface area, high water solubility, low viscosity, high water retention, and the availability of numerous modifiable surface groups. Dendritic glucans can be synthesized by in vivo biocatalysis reactions using glucosyl-1-phosphate as a substrate, which can be obtained from plant, animal, or microbial sources. They can also be synthesized by in vitro methods using sucrose or starch as a substrate, which may be more suitable for large-scale industrial production. The large numbers of hydroxyl groups on the surfaces of dendritic glucan provide a platform for diverse derivatizations, including nonreducing end, hydroxyl functionalization, molecular degradation, and conjugation modifications. Due to their unique physicochemical and functional attributes, dendritic glucans have been widely applied in the food, pharmaceutical, biomedical, cosmetic, and chemical industries. For instance, they have been used as delivery systems, adsorbents, tissue engineering scaffolds, biosensors, and bioelectronic components. This article reviews progress in the design, synthesis, and application of dendritic glucans over the past several decades.

Development of phytoglycogen-derived core-shell-corona nanoparticles complexed with conjugated linoleic acid

Phytoglycogen-derived self-assembled nanoparticles (SMPG/CLA) and enzymatic-assembled nanoparticles (EMPG/CLA) were fabricated for delivery of conjugated linoleic acid (CLA). After measuring the loading rate and yield, the optimal ratio for both assembled host-guest complexes was 1 : 10, and the maximum loading rate and yield for EMPG/CLA were 1.6% and 88.1%, respectively, higher than those of SMPG/CLA. Structural characterization studies showed that the assembled inclusion complexes were successfully constructed, and had a specific spatial architecture with inner-core amorphous and external-shell crystalline parts. A higher protective effect against oxidation of EMPG/CLA was observed than that of SMPG/CLA, supporting efficient complexation for a higher order crystalline structure. After 1 h of gastrointestinal digestion under the simulated conditions, 58.7% of CLA was released from EMPG/CLA, which was lower than that released from SMPG/CLA (73.8%). These results indicated that in situ enzymatic-assembled phytoglycogen-derived nanoparticles might be a promising carrier platform for protection and targeted delivery of hydrophobic bioactive ingredients.

[Efficacy and safefy of Polymyxin B treatment for neutropenic patients suffering from refractory Gram-negative bacterial bloodstream infection]

Objective: To assess the efficacy and safety of polymyxin B in neutropenic patients with hematologic disorders who had refractory gram-negative bacterial bloodstream infection. Methods: From August 2021 to July 2022, we retrospectively analyzed neutropenic patients with refractory gram-negative bacterial bloodstream infection who were treated with polymyxin B in the Department of Hematology of the First Affiliated Hospital of the Soochow University between August 2021 to July 2022. The cumulative response rate was then computed. Results: The study included 27 neutropenic patients with refractory gram-negative bacterial bloodstream infections. Polymyxin B therapy was effective in 22 of 27 patients. The median time between the onset of fever and the delivery of polymyxin B was 3 days [interquartile range (IQR) : 2-5]. The median duration of polymyxin B treatment was 7 days (IQR: 5-11). Polymyxin B therapy had a median antipyretic time of 37 h (IQR: 32-70). The incidence of acute renal dysfunction was 14.8% (four out of 27 cases), all classified as "injury" according to RIFLE criteria. The incidence of hyperpigmentation was 59.3%. Conclusion: Polymyxin B is a viable treatment option for granulocytopenia patients with refractory gram-negative bacterial bloodstream infections.

Molecular structure and characteristics of phytoglycogen, glycogen and amylopectin subjected to mild acid hydrolysis

The structure and properties of phytoglycogen and glycogen subjected to acid hydrolysis was investigated using amylopectin as a reference. The degradation took place in two stages and the degree of hydrolysis was in the following order: amylopectin > phytoglycogen > glycogen. Upon acid hydrolysis, the molar mass distribution of phytoglycogen or glycogen gradually shifted to the smaller and broadening distribution region, whereas the distribution of amyopectin changed from bimodal to monomodal shape. The kinetic rate constant for depolymerization of phytoglycogen, amylopectin, and glycogen were 3.45 × 10^-5/s, 6.13 × 10^-5/s, and 0.96 × 10^-5/s, respectively. The acid-treated sample had the smaller particle radius, lower percentage of α-1,6 linkage as well as higher rapidly digestible starch fractions. The depolymerization models were built to interpret the structural differences of glucose polymer during acid treatment, which would provide guideline to improve the structure understanding and precise application of branched glucan with desired properties.

Biosynthesis of maltodextrin-derived glucan dendrimer using microbial branching enzyme

Glucan dendrimers were developed with microbial branching enzyme (BE) treated maltodextrin. The molecular weight (M_w) of recombinant BE was 79.0 kDa, and its optimum activity was observed at pH 7.0 and 70 °C. BE converted different maltodextrins with dextrose equivalent value of 6 (MD6), 12 (MD12), or 19 (MD19) into the given glucan dendrimers, along with the marked increment of the molecular density (approximately 30-60 folds) and α-1,6 linkage percentage (up to 7.3-9.7%). Among three glucan dendrimers, the enzyme-treated MD12 showed a more homogeneous M_w distribution with the maximum M_w of 5.5 × 10⁶ g/mol, indicating that higher substrate catalytic specificity of BE for MD12 substrate. During transglycosylation with MD12 for 24 h, the shorter chains (degree of polymerization, DP < 13) increased from 73.9% to 83.0%, accompanying by a reduction of medium chains (DP13-24) and long chains (DP > 24). Moreover, the slowly digestible and resistant nutritional fractions were increased by 6.2% and 12.5%, respectively. The results suggested that the potentiality of BE structuring glucan dendrimer with tailor-made structure and functionality for industrial application.

Fabrication of phytoglycogen-derived core-shell nanoparticles: Structure and characterizations

The objective of this work was to investigate the fabrication of core-shell nanoparticles using phosphorylase-catalyzed chain extension of phytoglycogen, and to analyze the changes of structure and characterizations in detail. During the glucosylation reaction, the inorganic phosphate increased substantially up to 2.3 mg/mL in the initial 12 h, and then increased incrementally to 2.5 mg/mL at 24 h. The similar to trends was observed for increasing Mw and Rz over time, due to glucosyl transfers on the surface chain to form a corona around the phytoglycogen core with a larger size. Phosphorylase modification increases the percentages of longer chain fractions and the average chain length increased from degree of polymerization (DP) 11.6 to DP 48.2. The modified phytoglycogen exhibited the characteristic of B-type crystalline structure, indicating that the specific core-shell nanoparticle with inner amorphous nature and outer crystalline layer. The above results revealed that the potentiality of enzymatic chain elongation of phytoglycogen to design novel core-shell nanoparticle with tailor-made structure and functionality.

Mitochondria and cytochrome components released into the plasma of severe COVID-19 and ICU acute respiratory distress syndrome patients

INTRODUCTION

Proteomic analysis of human plasma by LC-ESI-MS/MS has discovered a limited number of new cellular protein biomarkers that may be confirmed by independent biochemical methods. Analysis of COVID-19 plasma has indicated the re-purposing of known biomarkers that might be used as prognostic markers of COVID-19 infection. However, multiple molecular approaches have previously indicated that the SARS-COV2 infection cycle is linked to the biology of mitochondria and that the response to infections may involve the action of heme containing oxidative enzymes.

METHODS

Human plasma from COVID-19 and ICU-ARDS was analyzed by classical analytical biochemistry techniques and classical frequency-based statistical approaches to look for prognostic markers of severe COVID-19 lung damage. Plasma proteins from COVID-19 and ICU-ARDS were identified and enumerated versus the controls of normal human plasma (NHP) by LC-ESI-MS/MS. The observation frequency of proteins detected in COVID-19 and ICU-ARDS patients were compared to normal human plasma, alongside random and noise MS/MS spectra controls, using the Chi Square (χ²) distribution.

RESULTS

PCR showed the presence of MT-ND1 DNA in the plasma of COVID-19, ICU-ARDS, as well as normal human plasma. Mitochondrial proteins such as MRPL, L2HGDH, ATP, CYB, CYTB, CYP, NDUF and others, were increased in COVID-19 and ICU-ARDS plasma. The apparent activity of the cytochrome components were tested alongside NHP by dot blotting on PVDF against a purified cytochrome c standard preparation for H₂O₂ dependent reaction with luminol as measured by enhanced chemiluminescence (ECL) that showed increased activity in COVID-19 and ICU-ARDS patients.

DISCUSSION

The results from PCR, LC-ESI-MS/MS of tryptic peptides, and cytochrome ECL assays confirmed that mitochondrial components were present in the plasma, in agreement with the established central role of the mitochondria in SARS-COV-2 biology. The cytochrome activity assay showed that there was the equivalent of at least nanogram amounts of cytochrome(s) in the plasma sample that should be clearly detectable by LC-ESI-MS/MS. The release of the luminol oxidase activity from cells into plasma forms the basis of a simple and rapid test for the severity of cell damage and lung injury in COVID-19 infection and ICU-ARDS.

Biofabrication, structure, and functional characteristics of a reuteran-like glucan with low digestibility

A novel reuteran-like glucan with low digestibility was fabricated using microbial glucanotransferase (GTase) treated maltodextrin. For GTase treated maltodextrin with DE 6, the molecular weight of reuteran-like glucan increased from 8.35 × 10⁴ to 5.14 × 10⁶ g/mol in the initial 6 h, increasing to 1.47 × 10⁷ g/mol at 72 h. The short chain fraction (DP 3-12) of reuteran-like glucan increased from 45.2 % to 100.0 %, accompanied by an increase in α-1,6 glycosidic linkage percentage from 3.9 % to 33.3 %. This reaction promoted rearrangements in glycosidic chains, leading to a substantial increase in resistant starch content (13.4 % to 37.4 %) in the reuteran-like glucan. During in vitro fecal fermentation for 48 h, the reuteran-like glucan yielded large amounts of short-chain fatty acids (212.33 mM), especially butyric acid (12.64 mM). Thus, reuteran-like glucan could be used as a low-digestible and highly fermentable fiber for controlling blood glucose levels and prebiotic potential.

[Allogeneic hematopoietic stem cell transplantation in acute leukemia patients with the SET-NUP214 fusion gene: Efficacy and survival analysis]

Objective: To investigate the clinical efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for patients with acute leukemia who are positive for the SET-NUP214 fusion gene (SET-NUP214⁺AL). Methods: This was a retrospective case series study. Clinical data of 18 patients with SET-NUP214⁺AL who received allo-HSCT in the First Affiliated Hospital of Soochow University and Soochow Hongci Hematology Hospital from December 2014 to October 2021 were retrospectively analyzed to investigate treatment efficacy and prognosis. The Kaplan-Meier method was used for survival analysis. Results: Of the 18 patients, 12 were male and 6 were female, and the median age was 29 years (range, 13-55 years). There were six cases of mixed phenotype acute leukemia (three cases of myeloid/T, two cases of B/T, one case of myeloid/B/T), nine cases of acute lymphoblastic leukemia (ALL) (one case of B-ALL and eight cases of T-ALL), and three cases of acute myeloid leukemia. All patients received induction chemotherapy after diagnosis, and 17 patients achieved complete remission (CR) after chemotherapy. All patients subsequently received allo-HSCT. Pre-transplantation status: 15 patients were in the first CR, 1 patient was in the second CR, 1 was in partial remission, and 1 patient did not reach CR. All patients were successfully implanted with stem cells. The median time of granulocyte and platelet reconstitution was +12 and +13 days, respectively. With a median follow-up of 23 (4-80) months, 15 patients survived, while 3 patients died. The cause of death was recurrence of SET-NUP214⁺AL after transplantation. After allo-HSCT, 5 patients relapsed. The estimated 3-year overall survival (OS) and relapse-free survival (RFS) rates were 83.3%±15.2% and 55.4%±20.7%, respectively. Among the 15 patients who achieved CR before transplantation, there was no significant difference in OS and RFS between haploidentical HSCT and matched sibling donor HSCT (all P>0.05). Conclusions: Allo-HSCT can improve the prognosis and long-term survival rate of patients with SET-NUP214⁺AL. Disease recurrence is the most important factor affecting long-term survival.

Enzymatic Approaches for Structuring Starch to Improve Functionality

Starch is one of the most abundant renewable biopolymers in nature and is the main constituent in the human diet and a raw material for the food industry. Native starches are limited in most industrial applications and often tailored by structural modification to enhance desirable attributes, minimize undesirable attributes, or create new attributes. Enzymatic approaches for structuring starch have become of interest to the food industry precisely because the reactions minimize the formation of undesirable by-products and coproducts and are therefore considered environmentally friendly methods for producing clean-label starches with better behavioral characteristics. Starches with improved functionalities for various applications are produced via enzyme hydrolysis and transfer reactions. Use of novel, multifunctional, starch-active enzymes to alter the structures of amylose and/or amylopectin molecules, and thus alter the starch's physiochemical attributes in a predictable and controllable manner, has been explored. This review provides state-of-the-art information on exploiting glycosyl transferases and glycosyl hydrolases for structuring starch to improve its functionalities. The characteristics of starch-active enzymes (including branching enzymes, amylomaltases, GH70 α-transglycosylases, amylosucrases, maltogenic amylases, cyclomaltodextrinases, neopullulanases, and maltooligosaccharide-forming amylases), structure–functionality-driven processing strategies, novel conversion products, and potential industrial applications are discussed.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 14 is March 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Effects of Human Milk Oligosaccharides in Infant Health Based on Gut Microbiota Alteration

The primary active components of breast milk are human milk oligosaccharides (HMOs). HMOs provide many benefits to infants, including regulating their metabolism, immune system, and brain development. Recent studies have emphasized that HMOs act as prebiotics by the metabolism of intestinal microorganisms to produce short-chain fatty acids, which are crucial for infant development. In addition, HMOs with different structural characteristics can form different microbial compositions. HMOs-induced predominant microbes, including Bifidobacterium infantis, B. bifidum, B. breve, and B. longum, and their metabolites demonstrated pertinent health-promoting properties. Meanwhile, HMOs could also directly reduce the occurrence of diseases through the effects of preventing pathogen infection. In this review, we address the probable function of HMOs inside the HMOs-gut microbiota-infant network, by describing the physiological functions of HMOs and the implications of diet on the HMOs-gut microbiota-infant network.

Muscle Fat Content Is Associated with Nonalcoholic Fatty Liver Disease and Liver Fibrosis in Chinese Adults

OBJECTIVES

Several studies have linked myosteatosis with nonalcoholic fatty liver disease (NAFLD) in individuals with obesity. The clinical significance of myosteatosis in individuals with NAFLD in the general population has not been well investigated. Here, we wanted to explore and compare the associations of NAFLD and liver fibrosis with muscle fat content and skeletal muscle mass (SMM) in a relatively large general population in China.

METHODS

We retrospectively included all participants who underwent abdominal CT scans in our health promotion center between April 2021 and October 2021. Muscle fat content was assessed by abdomen quantitative computed tomography (QCT) scans, and SMM was evaluated by bioelectrical impedance. NAFLD was assessed by ultrasonography. The NAFLD fibrosis score (NFS) and Fibrosis-4 Index (FIB-4) score were calculated to assess liver fibrosis.

RESULTS

Compared with participants without NAFLD, patients with NAFLD showed significantly increased intermuscular adipose tissue (IMAT%) (7.40±3.37% vs. 6.76±2.66%, P <0.01). According to a multiple logistic regression model, IMAT% (OR=1.091, 95% CI 1.030-1.155, P=0.003) was only independently correlated with NAFLD in obese participants. Mediation analysis showed that BMI mediated the association between IMAT% and NAFLD. In participants with NAFLD, increased IMAT% was independently associated with an increased intermediate to high risk of advanced fibrosis assessed by the NFS or FIB-4 score after adjusting for multiple potential confounders. However, SMM was only independently correlated with an intermediate to high risk for advanced fibrosis evaluated by the NFS and not by the FIB-4 score.

CONCLUSION

Increased muscle fat content is positively correlated with NAFLD and intermediate to high risk for advanced fibrosis in the general Chinese population.

LEDGF is a new growth factor in fetal serum

Fetal serum supports the immortal growth of mammalian cell lines in culture while adult serum leads to the terminal differentiation and death of cells in culture. Many of the proteins in fetal serum that support the indefinite division and growth of cancerous cell lines remain obscure. The peptides and proteins of fetal versus adult serum were analyzed by liquid chromatography, nano electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS). Three batches of fetal serum contained the Alpha Fetoprotein marker while adult serum batches did not. Insulin (INS), and insulin-like growth factor (ILGF), fibroblast growth factor (FGF), epidermal growth factor (EGF) and platelet derived growth factor (PDGF) were increased in fetal serum. New fetal growth factors including MEGF, HDGFRP and PSIP1 and soluble growth receptors such as TNFR, EGFR, NTRK2 and THRA were discovered. Addition of insulin or the homeotic transcription factor PSIP1, also referred to as Lens Epithelium Derived Growth Factor (LEDGF), partially restored the rounded phenotype of rapidly dividing cells but was not as effective as fetal serum. Thus, a new growth factor in fetal serum, LEDGF/PSIP1, was directly observed by tandem mass spectrometry and confirmed by add back experiments to cell culture media alongside insulin.

Engineering Escherichia coli for the High-Titer Biosynthesis of Lacto-N-tetraose

Lacto-N-tetraose (LNT), a member of the human milk oligosaccharides family, has received widespread attention because of its importance in infant health. We constructed a whole-cell biotransformation method in Escherichia coli BL21(DE3) for high-titer LNT synthesis. The approach was performed by using a systematic design and metabolic engineering based on the metabolic pathway of LNT. The lgtA (encoding β-1,3-N-acetylglucosaminyltransferase) and wbgO (encoding β-1,3-galactosyltransferase) genes were introduced into the engineered E. coli BL21(DE3) to construct an LNT-producing starting strain B1 (0.22 g/L). Then, the genes related to the LNT metabolic pathway were screened in two vectors to evaluate LNT synthesis. The lgtA-wbgO and galE-galT-galK genes were overexpressed through the two-plasmid system in E. coli BL21(DE3). The titer of LNT (3.42 g/L) had a gain of 14.55 times compared with that of B1. Furthermore, the ugd gene, which was associated with the UDP-Gal bypass pathway, was inactivated to further improve LNT production in shake-flask cultivation (4.14 g/L). The final fed-batch cultivation of the engineered strain produced 31.56 g/L of LNT. This study provided a strategy for the effective production of LNT in E. coli.

Characterization of a recombinant arginine deiminase from Halothermothrix orenii and its application in citrulline production

In recent years, arginine deiminase (ADI, EC 3.5.3.6) has attracted much attention as a biocatalyst that produces the functional amino acid l-citrulline from l-arginine and also as an anticancer enzyme. Here, we identified and characterized a putative ADI from the thermophilic bacterium Halothermothrix orenii. The H. orenii ADI (H-ADI) protein was expressed in Escherichia coli BL21(DE3) with a specific activity of 91.8 U/mg protein at 55°C and pH 6.5. The enzyme remained at 74% relative activity after incubation at 45°C for 180 min, only 25% at 50°C. The melting temperature was 56°C. H-ADI is not a metal-requiring enzyme; Ni²⁺ slightly improved the catalytic activity. The K_m and V_max for l-arginine were 55.5 mM and 156.8 μmol/min/mg protein, respectively. Moreover, three residues (Arg183, Arg237, and His273) were key to the formation of l-citrulline, as analyzed by alanine-scanning mutagenesis. Finally, the enzymatic synthesis of l-citrulline was carried out at 50°C with a conversion ratio reaching 99.03%. Together, these findings show that H-ADI is a promising biocatalyst for the production of l-citrulline.

Rebuilding the lid region from conformational and dynamic features to engineering applications of lipase in foods: Current status and future prospects

The applications of lipases in esterification, amidation, and transesterification have broadened their potential in the production of fine compounds with high cumulative values. Mostly, the catalytic triad of lipases is covered by either one or two mobile peptides called the "lid" that control the substrate channel to the catalytic center. The lid holds unique conformational allostery via interfacial activation to regulate the dynamics and catalytic functions of lipases, thereby highlighting its importance in redesigning these enzymes for industrial applications. The structural characteristic of lipase, the dynamics of lids, and the roles of lid in lipase catalysis were summarized, providing opportunities for rebuilding lid region by biotechniques (e.g., metagenomic technology and protein engineering) and enzyme immobilization. The review focused on the advantages and disadvantages of strategies rebuilding the lid region. The main shortcomings of biotechnologies on lid rebuilding were discussed such as negative effects on lipase (e.g., a decrease of activity). Additionally, the main shortcomings (e.g., enzyme desorption at high temperatre) in immobilization on hydrophobic supports via interfacial action were presented. Solutions to the mentioned problems were proposed by combinations of computational design with biotechnologies, and improvements of lipase immobilization (e.g., immobilization protocols and support design). Finally, the review provides future perspectives about designing hyperfunctional lipases as biocatalysts in the food industry based on lid conformation and dynamics.

Development of dendrimer-like glucan-stabilized Pickering emulsions incorporated with β-carotene

The impact of sugary maize dendrimer-like glucan octenyl succinate (OSA-SMDG) on the storage stability and antioxidant activity of β-carotene (BC)-loaded emulsions as well as bioaccessibility were investigated. The encapsulation efficiency of β-carotene in emulsions containing 3% OSA-SMDG (3OSA-SMDG-BC) or 5% OSA-SMDG (5OSA-SMDG-BC) was 89.6% and 94.9%, respectively. The antioxidant activity of both emulsions was higher than that of pure β-carotene. During simulated digestion, the particle size of emulsions was immediately reduced, whereas zeta-potential was continuously increased in intestinal digestion. After 2 h digestion, the free fatty acids (FFA) release rate of 3OSA-SMDG-BC and 5OSA-SMDG-BC was significantly higher than that of blank emulsion. Bioaccessibility of β-carotene encapsulated in 3OSA-SMDG-BC and 5OSA-SMDG-BC was also significantly higher than that of blank emulsion. FFA release rate and β-carotene bioaccessibility of 5OSA-SMDG-BC were higher than that of 3OSA-SMDG-BC. These results demonstrated that OSA-SMDG could be used to fabricate food-grade O/W Pickering emulsion as a delivery system for bioactive compounds.

Recent advances in intelligent food packaging materials: Principles, preparation and applications

Traditionally, food packaging is used for improving food quality and providing consumers with descriptions of products. A new generation of intelligent ("smart") packaging materials is being developed to continuously monitor the properties of packaged foods and provide real-time information about their maturity, quality, and safety. In this paper, recent research in the development, properties, and applications of intelligent food packaging materials is summarized. Initially, we review the different sensing methods that can be used to detect alterations in food properties, such as those based on changes in time, temperature, humidity, oxygen levels, pH, chemical composition, or microbial contamination. The different approaches that can be used to design intelligent packaging materials are then highlighted, including films, bar codes, and labels. A number of applications of these packaging materials are then discussed to demonstrate their potential in the food industry. Finally, the challenges and future directions of food packaging are discussed.

Deciphering molecular interaction and digestibility in retrogradation of amylopectin gel networks

The impact of the internal part of aewx amylopectin on the gel network and digestibility during retrogradation was investigated using wx amylopectin as a reference. After β-amylolysis for 60 min (aewx-60), greater shifts in both λ_max value and absorbance of iodine binding profiles were observed, accompanied by an increment of short chains (DP 3-5) with reducing the external long chains (DP 17.2). For the amylopectin gels aged 7 days at 4 °C, aewx had greater intermolecular aggregation of double helices to form junction zones, resulting in remarkably higher G', which was significantly greater than that of wx amylopectin or aewx-60. Moreover, aewx amylopectin had a greater RS accompanied by a reduction in RDS after retrogradation. The gel network models of retrograded amylopectins were built to interpret more molecular interactions for aewx than those of wx. The results revealed that aewx amylopectin with a higher proportion of longer external chains prompted the flexibility to align and interact for the formation of double helices and enzyme-resistant structures.

Fabrication, Structure and Functional Characterizations of pH-Responsive Hydrogels Derived from Phytoglycogen

The pH-responsive hydrogels were obtained through successive carboxymethylation and phosphorylase elongatation of phytoglycogen and their structure and functional characterizations were investigated. Phytoglycogen (PG) was first carboxymethylated to obtain carboxymethyl phytoglycogen (CM-PG) with degree of substitution (DS) at 0.15, 0.25, 0.30, and 0.40, respectively. Iodine staining and X-ray diffraction analysis suggested that the linear glucan chains were successfully phosphorylase-elongated from the non-reducing ends at the CM-PG surface and assembled into the double helical segments, leading to formation of the hydrogel. The DS of CM-PG significantly influenced elongation of glucan chains. Specifically, fewer glucan chains were elongated for CM-PG with higher DS and the final glucan chains were shorter, resulting in lower gelation rate of chain-elongated CM-PG and lower firmness of the corresponding hydrogels. Scanning electron microscope observed that the hydrogels exhibited a porous and interconnected morphology. The swelling ratio and volume of hydrogels was low at pH 3–5 and then became larger at pH 6–8 due to electrostatic repulsion resulting from deprotonated carboxymethyl groups. Particularly, the hydrogel prepared from chain-elongated CM-PG (DS = 0.25) showed the highest sensitivity to pH. These results suggested that phosphorylase-treated CM-PG formed the pH-responsive hydrogel and that the elongation degree and the properties of hydrogels depended on the carboxymethylation degree. Thus, it was inferred that these hydrogels was a potential carrier system of bioactive substances for their targeted releasing in small intestine.

Effect of New Frying Technology on Starchy Food Quality

Frying is commonly used by consumers, restaurants, and industries around the globe to cook and process foods. Compared to other food processing methods, frying has several potential advantages, including reduced processing times and the creation of foods with desirable sensory attributes. Frying is often used to prepare starchy foods. After ingestion, the starch and fat in these foods are hydrolyzed by enzymes in the human digestive tract, thereby providing an important source of energy (glucose and fatty acids) for the human body. Conversely, overconsumption of fried starchy foods can promote overweight, obesity, and other chronic diseases. Moreover, frying can generate toxic reaction products that can damage people's health. Consequently, there is interest in developing alternative frying technologies that reduce the levels of nutritionally undesirable components in fried foods, such as vacuum, microwave, air, and radiant frying methods. In this review, we focus on the principles and applications of these innovative frying technologies, and highlight their potential advantages and shortcomings. Further development of these technologies should lead to the creation of healthier fried foods that can help combat the rise in diet-related chronic diseases.

Development of a novel starch-based dietary fiber using glucanotransferase

In this study, a glucanotransferase from prokaryotic Azotobacter chroococcum NCIMB 8003 was recombinantly expressed and its biochemical characteristics and bioconversion ability for starch were investigated. The purified enzyme has the optimum activity at 55 °C and pH 6.5-7.0, as well as a melting temperature of 62 °C. The double-charged ion Ca2+ stimulated the activity of the enzyme by approximately 2.4 times. The kinetic parameters and specificity analysis revealed that this glucanotransferase had a higher affinity for high-amylose starch. During the transglycosylation reaction, the starch molecule was converted into a relatively small polymer with a narrow size distribution. For the enzyme modification of high-amylose starch for 72 h, the amount of α-1,6 linkages increased from 1.9% to 22.7% and the content of resistant starch (RS) increased from 3.18% to 17.83%. In addition, the fine structure displayed the reuteran-like highly branched glucan linked by single linear α-1,6 linkages and α-1,4/6 branching points. These results revealed that a promising prebiotic dietary fiber was synthesized from starch with glucanotransferase modification.

Food Matrix Effects for Modulating Starch Bioavailability

As the prevalence of obesity and diabetes has continued to increase rapidly in recent years, dietary approaches to regulating glucose homeostasis have gained more attention. Starch is the major source of glucose in the human diet and can have diverse effects, depending on its rate and extent of digestion in the small intestine, on postprandial glycemic response, which over time is associated with blood glucose abnormalities, insulin sensitivity, and even appetitive response and food intake. The classification of starch bioavailability into rapidly digestible starch, slowly digestible starch, and resistant starch highlights the nutritional values of different starches. As starch is the main structure-building macroconstituent of foods, its bioavailability can be manipulated by selection of food matrices with varying degrees of susceptibility to amylolysis and food processing to retain or develop new matrices. In this review, the food factors that may modulate starch bioavailability, with a focus on food matrices, are assessed for a better understanding of their potential contribution to human health. Aspects affecting starch nutritional properties as well as production strategies for healthy foods are also reviewed, e.g., starch characteristics (different type, structure, and modification), food physical properties (food form, viscosity, and integrity), food matrix interactions (lipid, protein, nonstarch polysaccharide, phytochemicals, organic acid, and enzyme inhibitor), and food processing (milling, cooking, and storage).

Linear and Gaussian Analysis of a Single Enzyme Molecule by LC-MS

The alkaline phosphatase-streptavidin enzyme amplification conjugate (APSA) was diluted and quantified to the equivalent of one enzyme molecule injected on column by monitoring the production of excess adenosine from adenosine monophosphate (AMP) using sensitive and selective enzyme-linked mass spectrometric assay. The APSA enzyme conjugate has a mass of about 195 kDa and catalyzed the production of millions of enzyme products over the course of incubation that may be sensitively quantified by liquid chromatography, electrospray ionization, and mass spectrometry. APSA enzyme conjugate from fg/mL to ag/mL alongside 0 g/mL (control) was incubated with the substrate 1 mM AMP for 2 h in free solution before collecting a 1 μL of sample of the enzyme product adenosine for injection and analysis by LC-MS. The enzyme product adenosine showed a Gaussian distribution after log₁₀ transformation. The safe limit of detection and quantification was approximately 250 zg of APSA enzyme conjugate injected on column. A linear signal with acceptable error was observed at the mass of the enzyme product adenosine from 10 to 10000 zg of APSA enzyme conjugate injected, compared to controls without enzyme. It was possible to make a linear and Gaussian measurement to the single molecule range of the universal APSA enzyme amplification conjugate per micro liter injected with approximately 10% error. This study describes the first linear and Gaussian quantification of enzyme product from the equivalent of one enzyme conjugate molecule injected onto LC-MS for analysis.

The evolutionary background and functional consequences of the rs2071307 polymorphism in human tropoelastin

Elastin is a major polymeric protein of the extracellular matrix, providing critical properties of extensibility and elastic recoil. The rs2071307 genomic polymorphism, resulting in the substitution of a serine for a glycine residue in a VPG motif in tropoelastin, has an unusually high minor allele frequency in humans. A consequence of such allelic heterozygosity would be the presence of a heterogeneous elastin polymer in up to 50% of the population, a situation which appears to be unique to Homo sapiens. VPG motifs are extremely common in hydrophobic domains of tropoelastins and are the sites of transient β-turns that are essential for maintaining the conformational flexibility required for its function as an entropic elastomer. Earlier data demonstrated that single amino acid substitutions in tropoelastin can have functional consequences for polymeric elastin, particularly when present in mixed polymers. Here, using NMR and molecular dynamics approaches, we show the rs2071307 polymorphism reduces local propensity for β-turn formation, with a consequent increase in polypeptide hydration and an expansion of the conformational ensemble manifested as an increased hydrodynamic radius, radius of gyration and asphericity. Furthermore, this substitution affects functional properties of polymeric elastin, particularly in heterogeneous polymers mimicking allelic heterozygosity. We discuss whether such effects, together with the unusually high minor allele frequency of the polymorphism, could imply some some evolutionary advantage for the heterozygous state.

[CAR T-cell bridging to allo-HSCT for relapsed/refractory B-cell acute lymphoblastic leukemia: the follow-up outcomes]

Objective: This study aims to investigate the efficacy and safety of chimeric antigen receptor (CAR) T-cell bridging allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the treatment of recurrent and refractory acute B-lymphocytic leukemia (R/R B-ALL) . Methods: A total of 50 R/R B-ALL patients who underwent CAR T-scell therapy to bridge allo-HSCT in the First Affiliated Hospital of Soochow University from January 2017 to May 2019 were retrospectively analyzed. The overall survival (OS) rate, event-free survival (EFS) rate, cumulative recurrence rate (CIR) , and transplant-related mortality (TRM) of patients with different bone marrow minimal residual disease (MRD) levels were analyzed before and after CAR T-cell infusion and before allo-HSCT. Results: The response rate of CAR T-cell therapy and the incidence rate of severe cytokine release syndrome were 92% and 28% , respectively. During 55 infusions, no treatment-related deaths occurred in any of the patients. The median time of CAR T-cell infusion to allo-HSCT was 54 (26-232) days, the median follow-up time after CAR T-cell infusion was 637 (117-1097) days, and the 1-year OS and EFS rates were (80.0±5.7) % and (60.0±6.9) % . The 1-year CIR and TRM after allo-HSCT were (28.0±0.4) % and (8.0±0.2) % . After CAR T-cell infusion and before allo-HSCT, patients with bone marrow MRD<0.01% had a significantly longer EFS [ (70.0±7.2) % vs (20.0±12.6) % , P<0.001; (66.7±7.5) % vs (36.4±14.5) % , P=0.008]and lower CIR [ (25.0±0.5) % vs (70.0±2.6) % , P<0.001; (23.08±0.47) % vs (45.45±2.60) % , P=0.038]. Conclusion: CAR T-cell therapy bridging allo-HSCT is safe and effective for recurrent and refractory B-ALL.

Reuteransucrase-catalytic kinetic modeling and functional characteristics for novel prebiotic gluco-oligomers

This work describes the reuteransucrase-catalyzed reaction and structural characterization as well as in vitro fermentation for the acceptor products of gluco-oligomers from sucrose and maltose. At a low concentration of sucrose, the production of gluco-oligomers was favored, resulting in a relatively large number of acceptor products (DP3-5). A mathematical model was also proposed to simulate gluco-oligomer production depending on the reaction conditions. The fine structures of major linear gluco-oligomer fractions for a sucrose : maltose ratio of 1 : 1 were assigned as follows: α-d-Glcp-(1→6)-α-d-Glcp-(1→4)-d-Glcp, α-d-Glcp-(1→4)-α-d-Glcp-(1→4)-α-d-Glcp-(1→4)-d-Glcp, α-d-Glcp-(1→4)-α-d-Glcp-(1→6)-α-d-Glcp-(1→4)-d-Glcp, and α-d-Glcp-(1→6)-α-d-Glcp-(1→4)-α-d-Glcp-(1→6)-α-d-Glcp-(1→4)-d-Glcp, respectively. Compared with dextran and GOS57, the results of fermentation selectivity indicated that gluco-oligomers promoted the proliferation of gut bacteria and total SCFA production with a higher concentration of propionate. These data suggested that the gluco-oligomers synthesized via the reuteransucrase acceptor reaction had a prebiotic effect on gastrointestinal health.

In situ and real-time insight into Rhizopus chinensis lipase under high pressure and temperature: Conformational traits and biobehavioural analysis

An in situ and real-time investigation was performed using an optical cell system and in-silico analysis to reveal the impacts of pressure and temperature on the conformational state and behaviours of Rhizopus chinensis lipase (RCL). The fluorescence intensity (FI) of RCL increased remarkably under high pressure, and part of this increase was recovered after depressurization. This result displayed the partially reversible conformational change of RCL, which may be associated with the local change of Trp224 near the catalytic centre. High temperature caused a significant loss of secondary structure, whereas the α-helical segments including the lid were preserved by high pressure even at temperatures over 60 °C. The parameters of enzymatic reaction monitored by UV showed that the hydrolysis rate was remarkably enhanced by the pressure of 200 MPa. In the pressure range of 0.1-200 MPa, the active volume measured by the in situ system decreased from -2.85 to -6.73 mL/mol with the temperature increasing from 20 °C to 40 °C. The high catalytic capacity of the lipase under high pressure and high temperature was primarily attributed to pressure protection on RCL.

Characterizations and Bioavailability of Dendrimer-like Glucan Nanoparticulate System Containing Resveratrol

In this study, sugary maize dendrimer-like glucan (SMDG) was used as a delivery carrier for improving the bioavailability of resveratrol (RES). After optimization, the solubility of RES in RES-SMDG markedly increased to approximately 9.1 times that of the raw RES solution. The structural characterizations of the RES-SMDG formulation showed crystal RES was entrapped in the SMDG matrix for the amorphous state due to the strong intermolecular hydrogen bonds between the -OH of RES and glucan chains. In this case, antioxidant activity of RES-SMDG was markedly higher than that of the raw RES solution. In the Caco-2 cell model, the P_app value of RES in the RES-SMDG group was slightly higher than those of common permeable compounds, while the cellular uptake was significantly improved. RES-SMDG also exhibited protective effects against cellular damage under oxidative stress. The results indicated that SMDG is an attractive carrier to encapsulate and protect hydrophilic bioactive ingredients.