Adverse reactions of piperacillin: A literature review of case reports.

Aim: This study aimed to summarize case reports of adverse drug reactions (ADRs) caused by piperacillin and explore their effects on human organs in real-world settings. Method: Case reports of piperacillin ADRs were collected by searching databases such as PubMed, Embase, Web of Science, CNKI, WanFang, and VIP from inception to December 2022. Results: A total of 170 patients were ultimately included. The results revealed that ADRs caused by piperacillin were primarily associated with the entire body, followed by the blood system, skin and soft tissues, and the nervous system. The most frequently reported cases included anaphylactic shock, drug fever, rash, and thrombocytopenia. The most severe ADRs were identified as anaphylactic shock and bullous epidermal necrolysis. Furthermore, a comparison was made between systemic adverse reactions caused by piperacillin as a single drug and two composite preparations of piperacillin/ß-lactamase inhibitor. ADRs not mentioned in the instructions included convulsions or hallucinations and Kounis syndrome (KS). Conclusion: This review suggests that the most severe ADRs associated with piperacillin are toxic epidermal necrolysis and anaphylactic shock. Rare ADRs caused by piperacillin, such as myoclonic jerks, hallucinations, and KS, were identified. The most common symptom with domestic preparations of piperacillin/sulbactam and piperacillin sodium was dyspnea.

A Comprehensively Prognostic and Immunological Analysis of PARP11 in Pan-cancer.

Poly (ADP ribose) polymerase family member 11(PARP11) has important immune regulatory functions in viral infection and tumor immune response. Particularly, PARP11 showed protumor activities in multiple preclinical murine models. However, no systematic pan-cancer analysis has been conducted to explore PARP11 function. In this study we used multiple databases to assess PARP11 expression, which associations with clinical outcomes, immune checkpoint factors, prognostic significance, genomic characteristics, and immunological aspects. The analysis revealed varying expression levels of PARP11 across different cancer types and a significant correlation between its expression and immune cell infiltration. Insights from the CellMiner database suggest a strong link between PARP11 expression and sensitivity to anticancer drugs, highlighting its potential as a therapeutic target. Moreover, PARP11 expression correlates with patient survival during anti-PD1 and anti-CTLA4 treatments, suggested that PARP11 would be a predictor of immune checkpoint inhibitor (ICI) treatment. In summary, PARP11 would be a potential immunoregulatory target and a diagnosis and prognosis marker for certain types of cancers. The detailed mechanisms of PARP11 in tumor immune responses need to be further investigated.

Silver-Catalyzed Dearomative Skeletal Editing of Indazoles by Donor Carbene Insertion.

Given the prevalence of heterocyclic scaffolds in drug-related molecules, converting these highly modular heterocyclic scaffolds into structural diversified and dearomatized analogs is an ideal strategy for improving their physicochemical and pharmacokinetic properties. Here, we described an efficient method for silver carbene-mediated dearomative N-N bond cleavage leading to skeletal hopping between indazole and 1,2-dihydroquinazoline via a highly selective single-carbon insertion procedure. Using this methodology, a series of dihydroquinazoline analogues with diarylmethylene-substituted quaternary carbon centers were constructed with excellent yields and good functional group compatibility, which was further illustrated by the late-stage diversification of important pharmaceutically active ingredients. DFT calculations indicated that the silver catalyst not only induces the formation of the silver carbene, but also activates the diazahexatriene intermediate, which plays a crucial role in the formation of the C-N bond.

Effect of electroacupuncture on ventricular structure and function in rats with myocardial ischemia-reperfusion injury. / ç”µé’ˆå¯¹å¿ƒè‚Œç¼ºè¡€å†çŒæ³¨æŸä¼¤å¤§é¼ å¿ƒå®¤ç»“æž„å’ŒåŠŸèƒ½çš„å½±å“.

OBJECTIVES: To observe the effect of electroacupuncture (EA) on changes of ventricular structure and function in rats with myocardial ischemia-reperfusion injury (MIRI), so as to explore its potential mechanisms underlying improvement of ventricular remodeling after MIRI. METHODS: Forty male SD rats were randomly divided into 4 groups：sham operation group, model group, EA group and medication (sacubactril valsartan, LCZ696) group, with 10 rats in each group. The MIRI model was established by ligation of the left anterior descending coronary artery and reperfusion. EA (2 Hz/100 Hz, 2 mA) was applied to bilateral "Neiguan" (PC6) for 20 min, once every other day for 21 d. Rats of the medication group received gavage of LCZ696 (60 mg·kg-1·d-1). After the intervention, echocardiography was used to detect the ejection fraction (EF) and fractional shortening (FS) of the left ventricle, and the contents of serum tumor necrosis factor-α(TNF-α), vascular cell adhesion molecule-1(VCAM-1) and intercellular cell adhesion molecule-1(ICAM-1) were assayed by enzyme-linked immunosorbent assay. The pathological changes of myocardial tissue were observed after HE staining. The Masson staining was used to evaluate the myocardial collagen deposition and myocardial fibrosis. The mRNA expression levels of collagen Ⅰ and Ⅲ and connective tissue growth factor (CTGF) in the myocardial tissue were detected by quantitative real-time PCR, and the expression levels of IL-1ß and IL-18 were detected by Western blot. RESULTS: In contrast to the sham operation group, the EF and FS levels of the left ventricle were ob-viously decreased (P<0.001), while the contents of serum TNF-α, VCAM-1 and ICAM-1, the proportion of myocardial fibrosis area, the mRNA expression levels of myocardial collagen Ⅰ, collagen Ⅲ and CTGF, the expression levels of IL-1ß and IL-18 were significantly increased (P<0.001, P<0.000 1, P<0.05, P<0.01) in the model group. Compared with the model group, the EF and FS levels were remarkably increased (P<0.01), whereas the contents of serum TNF-α, VCAM-1 and ICAM-1, the proportion of myocardial fibrosis area, the mRNA expression levels of myocardial collagen Ⅰ, collagen Ⅲ and CTGF, and the expression levels of IL-1ß and IL-18 were significantly down-regulated (P<0.001, P<0.01, P<0.05) in both the medication and EA groups. No significant differences were found between the EA and medication groups in all the indexes mentioned above. CONCLUSIONS: EA can improve the left-ventricular fibrosis and function, delay or reverse ventricular remodeling in MIRI rats, which may be related to its functions in down-regulating myocardial inflammatory response and mRNA expression levels of myocardial collagen Ⅰ, collagen Ⅲ and CTGF.

Novel Calcium-Binding Peptide from Bovine Bone Collagen Hydrolysates and Its Potential Pro-Osteogenic Activity via Calcium-Sensing Receptor (CaSR).

SCOPE: This paper aims to explore the osteogenic activity and potential mechanism of the peptide-calcium chelate, and provides a theoretical basis for peptide-calcium chelates as functional foods to prevent or improve osteoporosis. METHODS AND RESULTS: In this research, a novel peptide (Phe-Gly-Leu, FGL) with a high calcium-binding capacity is screened from bovine bone collagen hydrolysates (CPs), calcium binding sites of which mainly included carbonyl, amino and carboxyl groups. The FGL-Ca significantly enhances the osteogenic activity of MC3T3-E1 cells (survival rate, differentiation, and mineralization). The results of calcium fluorescence labeling and molecular docking show that FGL-Ca may activate calcium-sensing receptor (CaSR), leading to an increase in intracellular calcium concentration, then enhancing osteogenic activity of MC3T3-E1 cells. Further research found that FGL-Ca significantly promotes the mRNA and protein expression levels of CaSR, transforming growth factor ß (TGF-ß1), TGF-ß-type II receptor (TßRII), Smad2, Smad3, osteocalcin (OCN), alkaline phosphatase (ALP), osteoprotegrin (OPG), and collagen type I (COLI). Subsequently, in the signal pathway intervention experiment, the expression levels of genes and proteins related to the TGF-ß1/Smad2/3 signaling pathway that are promoted by FGL-Ca are found to decrease. CONCLUSIONS: These results suggest that FGL-Ca may activate CaSR, increase intracellular calcium concentration, and activate TGF-ß1/Smad2/3 signaling pathway, which may be one of the potential mechanisms for enhancing osteogenic activity.

Phosphorylation modification of bovine bone collagen peptide enhanced its effect on mineralization of MC3T3-E1 cells via improving calcium-binding capacity.

This study aimed to investigate the effect of phosphorylation modification of collagen peptide on its calcium-binding capacity and pro-mineralization activity. In this study, collagen peptide (Leu-Thr-Phe, LTF) and phosphorylated LTF (P-LTF) were synthesized and further chelated with calcium ions. The results showed that phosphorylation of LTF significantly enhanced its calcium-binding capacity. Spectra analysis revealed that the calcium-binding sites of P-LTF were mainly carbonyl, carboxyl, and phosphate groups. Molecular docking further demonstrated that the phosphate group introduced by phosphorylation enhanced the calcium-binding capacity of LTF by ionic bonds and coordination bonds. The stability analysis results suggested that intestinal fluid could repair the peptide-calcium complex destroyed by gastric fluid. The cell experiment displayed that P-LTF-Ca significantly improved the mineralization activity of MC3T3-E1 cells, and the order of effective influence was P-LTF-Ca > LTF-Ca > P-LTF > LTF. This study provided the theoretical basis for the potential application of phosphorylation modification in improving bone health.

Correlation between serum vitamin D level and uterine volume in girls with idiopathic central precocious puberty.

OBJECTIVES: Investigate serum vitamin D (vit D) levels' relation to uterine volume in idiopathic central precocious puberty (ICPP) girls and compare findings with normal peers. METHODS: Analyzed 278 ICPP cases from January 2017 to September 2022 alongside 239 normally developing girls. Collected clinical data and lab markers and performed subgroup analysis based on vit D levels. Correlation and regression analyses were conducted. RESULTS: The ICPP group exhibited elevated uterine volume and lower serum vit D compared to controls (p<0.05). A weak negative correlation was noted between vit D and uterine volume in ICPP (r=-0.193, p=0.004), and no such correlation in controls (r=-0.073, p=0.319). The ICPP vit D deficiency subgroup displayed higher uterine volume than the insufficiency and sufficiency subgroups (p<0.05). Uterine volume in the insufficiency subgroup exceeded the sufficiency subgroup (p<0.05). After adjusting for confounders, lower vit D is linked to increased ICPP uterine volume (non-standardized regression coefficient ß=-25.55, 95 % CI= -46.23, -4.87, p=0.016). A Limited correlation between vit D and uterine volume was seen in girls with normal pubertal timing. CONCLUSIONS: We demonstrated a correlation between vit D and uterine volume in ICPP girls, absent in normal peers. ICPP girls often exhibit lower vit D levels and increased uterine volume. Further research is vital for understanding vit D's role in ICPP pathogenesis and guiding prevention and treatment strategies.

DTCO optimizes critical path nets to improve chip performance with timing-aware OPC in deep ultraviolet lithography.

Design technology co-optimization (DTCO) is a potential approach to tackle the escalating expenses and complexities associated with pitch scaling. This strategy offers a promising solution by minimizing the required design dimensions and mitigating the pitch scaling trend. It is worth noting that lithography has played a significant role in dimensional scaling over time. This paper proposes a DTCO flow to reduce the impact of the process variation (PV) band and edge placement error (EPE). First, we performed the digital back-end design of the high-performance processor and got the test layout; second, we executed timing analysis on the test layout to get the critical path net that affects the chip performance; third, we proposed the timing-aware optimized optical proximity correction (OPC) method to optimize the PV band and EPE by adjusting the weights of critical path net merit points, optimizing the generation of the sub-resolution assistant feature, giving tighter EPE specs for merit points on the critical path net, and placing denser merit points as well as denser breakpoints for the critical path net to obtain greater freedom in the OPC process. Finally, it is verified that our proposed DTCO process can significantly reduce the EPE and lead to a slight decrease in the PV band of the chip while maintaining the same process windows.

Mstnet: method for glaucoma grading based on multimodal feature fusion of spatial relations.

Objective.The objective of this study is to develop an efficient multimodal learning framework for the classification of glaucoma. Glaucoma is a group of eye diseases that can result in vision loss and blindness, often due to delayed detection and treatment. Fundus images and optical coherence tomography (OCT) images have proven valuable for the diagnosis and management of glaucoma. However, current models that combine features from both modalities often lack efficient spatial relationship modeling.Approach.In this study, we propose an innovative approach to address the classification of glaucoma. We focus on leveraging the features of OCT volumes and harness the capabilities of transformer models to capture long-range spatial relationships. To achieve this, we introduce a 3D transformer model to extract features from OCT volumes, enhancing the model's effectiveness. Additionally, we employ downsampling techniques to enhance model efficiency. We then utilize the spatial feature relationships between OCT volumes and fundus images to fuse the features extracted from both sources.Main results.Our proposed framework has yielded remarkable results, particularly in terms of glaucoma grading performance. We conducted our experiments using the GAMMA dataset, and our approach outperformed traditional feature fusion methods. By effectively modeling spatial relationships and combining OCT volume and fundus map features, our framework achieved outstanding classification results.Significance.This research is of significant importance in the field of glaucoma diagnosis and management. Efficient and accurate glaucoma classification is essential for timely intervention and prevention of vision loss. Our proposed approach, which integrates 3D transformer models, offers a novel way to extract and fuse features from OCT volumes and fundus images, ultimately enhancing the effectiveness of glaucoma classification. This work has the potential to contribute to improved patient care, particularly in the early detection and treatment of glaucoma, thereby reducing the risk of vision impairment and blindness.

[Lidong needling therapy combined with functional exercise in treatment of upper limb lymphedema after breast cancer surgery: a randomized controlled trial].

OBJECTIVE: To observe the clinical efficacy of lidong needling therapy (acupuncture technique combined with therapeutic movement of the body) on upper limb lymphedema after breast cancer surgery in combination with functional exercise. METHODS: A total of 73 patients with postoperative lymphedema of breast cancer in the upper limbs were randomized into an observation group (36 cases) and a control group (37 cases). The routine nursing care and functional exercise were given in the control group, twice a day, for about 10-15 min each time, lasting 8 weeks. On the basis of the treatment as the control group, lidong needling therapy was applied to the acupionts on the affected upper limb, i.e. Jianyu (LI 15), Waiguan (TE 5), Hegu (LI 4) and ashi points (the most obvious swelling sites), as well as to bilateral Yinlingquan (SP 9) and Zusanli (ST 36), etc. The needles were retained for 30 min. While the needles retained, the patients were asked to move the affected shoulder to 90° by the sagittal anteflexion and keep it elevated. Simultaneously, the hand on the affected side was clenched and opened slowly and coordinately. Lidong needling therapy was delivered once every two days, three times weekly for 8 weeks. Before and after treatment, the difference of the circumference between the affected and healthy limbs, the score of visual analogue scale (VAS) for swelling and the score of disability of arm, shoulder and hand (DASH) were compared in the patients of the two groups. The clinical efficacy was evaluated. RESULTS: After 2, 4, 6 and 8 weeks of treatment, except for the circumference of the area 10 cm below the cubitel crease in the control group, the differences in the circumferences of the rest parts between the affected and healthy limbs were reduced in comparison with those before treatment in the two groups (P<0.01, P<0.05). After 6 weeks of treatment, in the observation group, for the circumference at the level of hand between the thumb and the index finger and that of the wrist, the differences between the affected and healthy limbs was smaller compared with those in the control group (P<0.05). After 8 weeks of treatment, except for the areas 5 cm below and above the cubitel crease, the differences of circumferences between the affected and healthy limbs in the observation group were smaller than those in the control group in the rest parts (P<0.01, P<0.05). After 8 weeks of treatment, the swelling VAS scores were reduced when compared with those before treatment in the two groups (P<0.05), and the score in the observation group was lower than that in the control group (P<0.01). After 4 and 8 weeks of treatment, DASH scores were reduced in comparison with those before treatment in the two groups (P<0.01). The total effective rate of the observation group was 83.3% (30/36), which was higher than that of the control group (35.1%, 13/37, P<0.01). CONCLUSION: Lidong needling therapy combined with the functional exercise obtains the satisfactory clinical effect on the upper limb lymphedema after breast cancer surgery. This treatment effectively relieves swelling and improves the upper limb function.

Electroacupuncture preconditioning protects against myocardial ischemia-reperfusion injury by modulating dynamic inflammatory response.

Background: The protective effects of electroacupuncture (EA) preconditioning against myocardial ischemia-reperfusion injury (MIRI) have been reported. However, the underlying mechanism remains unclear. Recent research has indicated that the dynamic inflammatory response following MIRI plays an essential role in the progression of myocardial injury. This study aimed to investigate the myocardial protective effects of EA preconditioning on MIRI in rats and to explore the relevant mechanism from the perspective of dynamic inflammatory response. Methods: A MIRI model was employed, and the rats were subjected to EA on Neiguan for four days prior to modeling. The myocardial protective effect of EA preconditioning was evaluated by echocardiography, Evans blue and triphenyltetrazolium chloride staining. Real-time polymerase chain reaction, Western blot, hematoxylin & eosin staining, and immunohistochemistry were utilized to detect the content of mitochondrial DNA, NOD receptor family protein 3 (NLRP3) inflammasome activation, neutrophil recruitment and macrophage infiltration in blood samples and myocardium below the ligation. Results: We found that EA preconditioning could accelerate the recovery of left ventricle function after MIRI and reduce the myocardial infarction area, thereby protecting the myocardium against MIRI. Furthermore, EA preconditioning was observed to ameliorate mitochondrial impairment, reduce the level of plasma mitochondrial DNA, modulate NLRP3 inflammasome activation, attenuate neutrophil infiltration, and promote the polarization of M1 macrophages towards M2 macrophages in the myocardium after MIRI. Conclusion: EA preconditioning could reduce plasma mtDNA, suppress overactivation of the NLRP3 inflammasome, facilitate the transition from the acute pro-inflammatory phase to the anti-inflammatory reparative phase after MIRI, and ultimately confer cardioprotective benefits.

Polymer self-assembly guided heterogeneous structure engineering towards high-performance low-frequency electromagnetic wave absorption.

Magnetic-dielectric synergy is currently regarded as among the most effective approaches to achieve low-frequency electromagnetic wave absorption (EMA). However, designing and fabricating EMA materials with tunable magnetic-dielectric balance towards high-performance low-frequency EMA remains challenging. Herein, a polymer self-assembly guided heterogeneous structure engineering strategy is proposed to fabricate hierarchical magnetic-dielectric nanocomposite. Polymer assemblies not only can be employed as intermediates to encapsulate metal-organic frameworks and load metal hydroxide, but also that they play a crucial role for the in-situ formation of polycrystalline FeCo/Co composite nanoparticles. As a result, the minimum reflection loss (RLmin) can reach -59.61 dB at 5.4 GHz (4.8 mm) with a 20 wt% filler loading, while the effective absorption bandwidth (EAB, RLmin ≤ -10 dB) is 2.16 GHz, exhibiting excellent low-frequency EMA performance. Systematic investigations demonstrate that hierarchical mesoporous carbon matrix that supports FeCo/Co composite nanoparticles is beneficial for optimizing impedance matching and increasing attenuation capacity. In general, this study opens up new prospects for developing magnetic-dielectric EMA materials using a polymer self-assembly guided heterogeneous structure engineering strategy, which may receive significant attention in future research.

Characterization of a Novel Milk-Clotting Aspartic Protease from Penicillium sp. and Structural Explanation for its High Milk-Clotting Index.

A novel milk-clotting enzyme isolated from Penicillium sp. ACCC 39790 (PsMCE) was prepared by heterologous expression. The recombinant PsMCE had an apparent molecular mass of 45 kDa and exhibited maximum casein hydrolysis activity at pH 4.0 and 50 °C. The PsMCE activity was enhanced by calcium ions and strongly inhibited by pepstatin A. Through hydrolysis pattern and cleavage site analyses, the milk-clotting activity of PsMCE was related to its specific hydrolysis between Phe105 and Met106 in the κ-casein proteins. The structural basis of PsMCE was characterized using homology modeling, molecular docking, and interactional analysis. The P1' region of PsMCE is critical for its selective binding to the hydrolytic site in κ-casein, and the hydrophobic forces play a decisive role in the specific cleavage of Phe105 and Met106. These interactional analyses between PsMCE and the ligand peptide clarified the fundamentals of its high milk-clotting index (MCI). PsMCE could be applied in cheese making due to its thermolability and high MCI value as a potential milk-clotting enzyme.

Damage and failure of underground subway stations under different soil constraint conditions.

Investigations from past earthquakes have shown that underground subway stations can suffer excessive deformation under strong seismic loads, leading to the damage of critical components and the collapse of structures. This study presents the results of finite element analyses on the seismic damage of underground subway stations installed under different soil constraint conditions. The plastic hinge distribution and damage characteristics of cut and cover double-storey and three-storey subway stations are analyzed using the finite element method software ABAQUS. Combined with the static analysis results of the column sections, a discriminant method for bending plastic hinges is presented. The numerical results show that the collapse of the subway stations begins with the failure of the bottom columns' bottom sections, which leads to the bending of the plates and the destruction of the whole structure. The bending deformation at the end section of columns has an approximatively linear relationship with the inter-storey drift ratio, and the change in soil conditions shows no apparent influence. The sidewall deformation behavior varies significantly under different soil conditions, and the bending deformation at the bottom section of sidewalls increases along with an increase in the soil-structure stiffness ratio at the same inter-storey drift deformation level. The sidewall bending ductility ratio of the double-storey and three-storey stations at the elastic-plastic drift ratio limit increases by 61.6% and 26.7%, respectively. In addition, the fitting curves between the component bending ductility ratio and inter-storey drift ratio based on the analysis results are also presented. The findings may provide a helpful reference for the seismic performance evaluation and design of underground subway stations.

Impact of Ultrasonication on the Self-Assembly Behavior and Gel Properties of Bovine Bone Collagen I.

This study deliberated the effect of ultrasonic treatment on collagen self-assembly behavior and collagen fibril gel properties. Bovine bone collagen I which had undergone ultrasonic treatment with different power (0-400 W) and duration (0-60 min) was analyzed. SDS-PAGE and spectroscopic analysis revealed that ultrasonic treatment decreased collagen molecular order degree and the number of hydrogen bonds, stretching collagen telopeptide regions while maintaining the integrity of the collagen triple-helical structure. Ultrasonic treatment (p ≤ 200 W, t ≤ 15 min) dispersed the collagen aggregates more evenly, and accelerated collagen self-assembly rate with a decreased but more homogeneous fibril diameter (82.78 ± 16.47-115.52 ± 19.51 nm) and D-periodicity lengths (62.1 ± 2.9-66.5 ± 1.8 nm) than that of the untreated collagen (119.15 ± 27.89 nm; 66.5 ± 1.8 nm). Meanwhile, ultrasonic treatment (p ≤ 200 W, t ≤ 15 min) decreased the viscoelasticity index and gel strength, enhancing thermal stability and promoting specific surface area and porosity of collagen fibril gels than that of the untreated collagen fibril gel. These results testified that collagen self-assembly behavior and collagen fibril gel properties can be regulated by ultrasonic treatment through multi-hierarchical structural alteration. This study provided a new approach for controlling in vitro collagen fibrillogenesis process so as to manufacture novel desirable collagen-based biomaterials with propitious performances for further valorization.

Emerging role of substance and energy metabolism associated with neuroendocrine regulation in tumor cells.

Cancer is the second most common cause of mortality in the world. One of the unresolved difficult pathological mechanism issues in malignant tumors is the imbalance of substance and energy metabolism of tumor cells. Cells maintain life through energy metabolism, and normal cells provide energy through mitochondrial oxidative phosphorylation to generate ATP, while tumor cells demonstrate different energy metabolism. Neuroendocrine control is crucial for tumor cells' consumption of nutrients and energy. As a result, better combinatorial therapeutic approaches will be made possible by knowing the neuroendocrine regulating mechanism of how the neuroendocrine system can fuel cellular metabolism. Here, the basics of metabolic remodeling in tumor cells for nutrients and metabolites are presented, showing how the neuroendocrine system regulates substance and energy metabolic pathways to satisfy tumor cell proliferation and survival requirements. In this context, targeting neuroendocrine regulatory pathways in tumor cell metabolism can beneficially enhance or temper tumor cell metabolism and serve as promising alternatives to available treatments.

Seven-layer analysis model of an optical waveguide excitation fluorescence microscopy.

In this paper, an optical waveguide evanescent field fluorescence microscopy is studied. Based on Maxwell's equation, a seven-layer theoretical analysis model is developed for the evaluation of an optical waveguide excitation fluorescence microscopy. The optical waveguide excitation fluorescence microscopy structure is systematically and comprehensively analysed at the wavelengths of 488, 532 and 646 nm for fluorescent dyes. The analysis results provide some useful suggestions, which will be beneficial to the research of an optical waveguide evanescent field fluorescence microscopy.

A novel calcium-binding peptide from bovine bone collagen hydrolysate and chelation mechanism and calcium absorption activity of peptide-calcium chelate.

A novel calcium-binding peptide from bovine bone collagen hydrolysate was screened based on a new target-the calcium-sensing receptor (CaSR), and its chelation mechanism and calcium absorption activity were investigated. Glu-Tyr-Gly exhibited superior binding affinities to CaSR because of its interaction with the active sites of the CaSR Venus Flytrap (VFT) domain. Glu-Tyr-Gly-Ca may exist in five potential chelation modes and its potential chelation mechanism was that calcium ions were located in the center and surrounded by ionic bonds (carboxyl group) and coordination bonds (carbonyl, amino, and carboxyl group). Glu-Tyr-Gly-Ca was slightly damaged in the intestinal fluid and at different temperatures, whereas it was severely damaged in the gastric fluid and acidic conditions. The results of the calcium dialysis percentage and Caco-2 cells experiments showed that Glu-Tyr-Gly-Ca possessed good calcium transport activity and bioavailability. The findings provided theoretical basis for Glu-Tyr-Gly-Ca as potential calcium supplement to improve intestinal calcium absorption.