Single chain antibody fragment (scFv) is a small molecule composed of a variable region of heavy chain (VH) and a variable region of light chain (VL) of an antibody, and these two chains are connected by a flexible short peptide. scFv is the smallest functional fragment with complete antigen-binding activity, which contains both the antibody-recognizing site and the antigen-binding site. Compared with other antibodies, scFv has the advantages of small molecular weight, strong penetration, low immunogenicity, and easy expression. Currently, the most commonly used display systems for scFv mainly include the phage display system, ribosome display system, mRNA display system, yeast cell surface display system and mammalian cell display system. In recent years, with the development of scFv in the field of medicine, biology, and food safety, they have also attracted much attention in the sectors of biosynthesis and applied research. This review summarizes the advances of scFv display systems in recent years in order to facilitate scFv screening and application.
Animals ; Immunoglobulin Variable Region/genetics* ; Immunoglobulin Fragments/metabolism* ; Single-Chain Antibodies/metabolism* ; Peptide Library ; Mammals/genetics*

OBJECTIVES: To study the level of serum vitamin K₂ (VitK₂) and its association with bone metabolism markers osteocalcin (OC), type I procollagen amino-terminal peptide (PINP), and type I collagen carboxy-terminal peptide (CTX) in children. METHODS: A prospective analysis was performed on 1 732 children who underwent routine physical examination from October 2020 to October 2021. The serum levels of VitK₂ and 25-hydroxy vitamin D [25(OH)D] were measured. According to age, they were divided into four groups: <1 year, 1-3 years group, >3-6 years group, and >6-14 years. A total of 309 children with 25(OH)D≥50 nmol/L were screened out, and serum levels of OC, PINP, and CTX were measured to investigate the correlation of the serum levels of OC, PINP, and CTX with serum VitK₂ levels in different age groups. RESULTS: The prevalence rate of serum VitK₂ deficiency was 52.31% (906/1 732). The VitK₂ deficiency group had higher prevalence rates of overweight/obesity and growth pain (≥3 years of age) than the normal VitK₂ group (P<0.05). There were differences in the prevalence rate of serum VitK₂ deficiency (P<0.0083) and the serum level of VitK₂ (P<0.05) between the 1-3 years group and the >6-14 years group. The <1 year group had a higher serum level of CTX and a lower serum level of PINP than the >3-6 years group and the >6-14 years group (P<0.05). The <1 year group had a lower serum level of OC than the >6-14 years group (P<0.05). Serum VitK₂ level was positively correlated with OC level (r_s=0.347, P<0.01), and CTX level was negatively correlated with PINP level (r_s=-0.317, P<0.01). CONCLUSIONS Serum VitK₂ deficiency may be associated with overweight/obesity. Serum VitK₂ may affect the level of OC and even bone health.
Child ; Humans ; Infant ; Biomarkers/metabolism* ; Collagen Type I/metabolism* ; Obesity/complications* ; Osteocalcin/metabolism* ; Overweight/complications* ; Peptide Fragments/metabolism* ; Peptides/metabolism* ; Procollagen/metabolism* ; Vitamin K/blood* ; Child, Preschool ; Adolescent ; Bone and Bones/metabolism*

The aim of the present study was to explore the correlation between ptk2b/PTK2B (protein tyrosine kinase 2 beta, a ptk2b-encoded protein) and the level of low density lipoprotein receptor-related protein-1 (LRP-1), as well as to uncover the relationship between the changes in beta amyloid protein (Aβ) levels in blood and brain and the expression of ptk2b in Aβ-induced cognitive dysfunction mice. A total of 64 3-month-old C57BL/6J mice were divided randomly into the experimental group and control group. All mice underwent the intracerebroventricular (i.c.v.) intubation. Mice in the experimental group received the i.c.v. infusion of oligomeric Aβ
Alzheimer Disease ; Amyloid beta-Peptides/metabolism* ; Animals ; Brain ; Cognitive Dysfunction/chemically induced* ; Disease Models, Animal ; Focal Adhesion Kinase 2 ; Hippocampus/metabolism* ; Mice ; Mice, Inbred C57BL ; Peptide Fragments

OBJECTIVE: Silicosis, caused by inhalation of silica dust, is the most serious occupational disease in China and the aim of present study was to explore the protective effect of Ang (1-7) on silicotic fibrosis and myofibroblast differentiation induced by Ang II. METHODS: HOPE-MED 8050 exposure control apparatus was used to establish the rat silicosis model. Pathological changes and collagen deposition of the lung tissue were examined by H.E. and VG staining, respectively. The localizations of ACE2 and α-smooth muscle actin (α-SMA) in the lung were detected by immunohistochemistry. Expression levels of collagen type I, α-SMA, ACE2, and Mas in the lung tissue and fibroblasts were examined by western blot. Levels of ACE2, Ang (1-7), and Ang II in serum were determined by ELISA. Co-localization of ACE2 and α-SMA in fibroblasts was detected by immunofluorescence. RESULTS: Ang (1-7) induced pathological changes and enhanced collagen deposition in vivo. Ang (1-7) decreased the expressions of collagen type I and α-SMA and increased the expressions of ACE2 and Mas in the silicotic rat lung tissue and fibroblasts stimulated by Ang II. Ang (1-7) increased the levels of ACE2 and Ang (1-7) and decreased the level of Ang II in silicotic rat serum. A779 enhanced the protective effect of Ang (1-7) in fibroblasts stimulated by Ang II. CONCLUSION Ang (1-7) exerted protective effect on silicotic fibrosis and myofibroblast differentiation induced by Ang II by regulating ACE2-Ang (1-7)-Mas axis.
Actins ; metabolism ; Angiotensin I ; blood ; pharmacology ; therapeutic use ; Angiotensin II ; blood ; Animals ; Animals, Newborn ; Cell Differentiation ; drug effects ; Cells, Cultured ; Collagen Type I ; metabolism ; Disease Models, Animal ; Lung ; metabolism ; pathology ; Myofibroblasts ; drug effects ; Peptide Fragments ; blood ; pharmacology ; therapeutic use ; Peptidyl-Dipeptidase A ; metabolism ; Rats, Wistar ; Silicosis ; metabolism ; pathology ; prevention & control

Angiotensin (Ang)-(1-7) is an important biologically-active peptide of the renin-angiotensin system. This study was designed to determine whether inhibition of Ang-(1-7) in the hypothalamic paraventricular nucleus (PVN) attenuates sympathetic activity and elevates blood pressure by modulating pro-inflammatory cytokines (PICs) and oxidative stress in the PVN in salt-induced hypertension. Rats were fed either a high-salt (8% NaCl) or a normal salt diet (0.3% NaCl) for 10 weeks, followed by bilateral microinjections of the Ang-(1-7) antagonist A-779 or vehicle into the PVN. We found that the mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA), and plasma norepinephrine (NE) were significantly increased in salt-induced hypertensive rats. The high-salt diet also resulted in higher levels of the PICs interleukin-6, interleukin-1beta, tumor necrosis factor alpha, and monocyte chemotactic protein-1, as well as higher gp91 expression and superoxide production in the PVN. Microinjection of A-779 (3 nmol/50 nL) into the bilateral PVN of hypertensive rats not only attenuated MAP, RSNA, and NE, but also decreased the PICs and oxidative stress in the PVN. These results suggest that the increased MAP and sympathetic activity in salt-induced hypertension can be suppressed by blockade of endogenous Ang-(1-7) in the PVN, through modulation of PICs and oxidative stress.
Angiotensin I ; antagonists & inhibitors ; metabolism ; Animals ; Antioxidants ; pharmacology ; Blood Pressure ; drug effects ; Hypertension ; chemically induced ; drug therapy ; Male ; Oxidative Stress ; drug effects ; Paraventricular Hypothalamic Nucleus ; drug effects ; Peptide Fragments ; antagonists & inhibitors ; metabolism ; Rats, Sprague-Dawley ; Reactive Oxygen Species ; metabolism ; Sodium Chloride, Dietary ; pharmacology

Animals ; Cells, Cultured ; Gastrointestinal Tract ; metabolism ; Neuroglia ; metabolism ; Neurons ; metabolism ; Peptide Fragments ; metabolism ; Peptides ; metabolism ; Proteins ; metabolism ; Rats

BACKGROUND: The Global Registry of Acute Coronary Events (GRACE) score is recommended by current ST-elevation myocardial infarction (STEMI) guidelines. But it has inherent defects. The present study aimed to investigate the more compatible risk stratification for Chinese patients with STEMI and to determine whether the addition of biomarkers to the Korea Acute Myocardial Infarction Registry (KAMIR) score could enhance its predictive value for long-term outcomes. METHODS: A total of 1093 consecutive STEMI patients were included and followed up 48.2 months. Homocysteine, hypersensitive C-reactive protein (hs-CRP), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were detected. The KAMIR score and the GRACE score were calculated. The performance between the KAMIR and the GRACE was compared. The predictive power of the KAMIR alone and combined with biomarkers were assessed by the receiver-operating characteristic (ROC) curve. RESULTS: The KAMIR demonstrated a better risk stratification and predictive ability than the GRACE (death: AUC = 0.802 vs. 0.721, P < 0.001; major adverse cardiovascular events (MACE): AUC = 0.683 vs. 0.656, P < 0.001). It showed that the biomarkers could independently predict death [homocysteine: HR = 1.019 (1.015-1.024), P < 0.001; hs-CRP: HR = 1.052 (1.000-1.104), P = 0.018; NT-pro BNP: HR = 1.142 (1.004-1.280), P = 0.021] and MACE [homocysteine: HR = 1.019 (1.015-1.024), P < 0.001; hs-CRP: HR = 1.012 (1.003-1.021), P = 0.020; NT-pro BNP: HR = 1.136 (1.104-1.168), P = 0.006]. When they were used in combination with the KAMIR, the area under the ROC curve (AUC) significantly increased for death [homocysteine: AUC = 0.802 vs. 0.890, Z = 5.982, P < 0.001; hs-CRP: AUC = 0.802 vs. 0.873, Z = 3.721, P < 0.001; NT-pro BNP: AUC = 0.802 vs. 0.871, Z = 2.187, P = 0.047; homocysteine, hs-CRP and NT-pro BNP: AUC = 0.802 vs. 0.940, Z = 6.177, P < 0.001] and MACE [homocysteine: AUC = 0.683 vs. 0.771, Z = 6.818, P < 0.001; hs-CRP: AUC = 0.683 vs. 0.712, Z = 2.022, P = 0.031; NT-pro BNP: AUC = 0.683 vs. 0.720, Z = 2.974, P = 0.003; homocysteine, hs-CRP and NT-pro BNP: AUC = 0.683 vs. 0.789, Z = 6.900, P < 0.001]. CONCLUSION The KAMIR is better than the GRACE in risk stratification and prognosis prediction in Chinese STEMI patients. A combination of above-mentioned biomarkers can develop a more predominant prediction for long-term outcomes.
Biomarkers ; blood ; C-Reactive Protein ; metabolism ; Humans ; Myocardial Infarction ; blood ; metabolism ; Natriuretic Peptide, Brain ; blood ; metabolism ; Peptide Fragments ; blood ; metabolism ; ROC Curve ; Registries ; Risk Factors ; ST Elevation Myocardial Infarction ; blood ; metabolism

Cardiac remodeling is a common pathological manifestation of various end-stage cardiovascular diseases, which leads to myocardial diastolic and systolic dysfunction, low ejection fraction which cannot meet the needs of systemic tissue and organ metabolism, and ultimate progress into heart failure. Excessive activation of the classical renin angiotensin system (RAS), which is the angiotensin-converting enzyme-angiotensin II-type 1 angiotensin II receptor axis (ACE2-Ang II-AT1R axis), plays a key role in the pathological process of cardiac remodeling and heart failure. Angiotensin-converting enzyme 2-angiotensin (1-7)-Mas axis [ACE2-Ang (1-7)-Mas axis] is an endogenous negative regulatory pathway of classical RAS, which can reduce its harmful effects. ACE2 is a monocarboxypeptidase that can hydrolyse Ang II and produce Ang (1-7), which has cardio-protective effects. Ang (1-7), via endogenous receptor Mas, plays the role of vasodilating, anti-proliferation and anti-differentiation, anti-fibrosis, anti-thrombosis and reversing myocardial remodeling. In recent years, with increasingly growing studies on the ACE2-Ang (1-7)-Mas axis, there are more understanding about their metabolic characteristics and mechanism of action. This article describes the role of ACE2 and Ang (1-7) in cardiac remodeling and heart failure and the related mechanisms, and discusses the potential benefits by regulating ACE2 activity and Ang (1-7) levels in clinical and experimental studies, hopefully providing potential therapeutic strategies.
Angiotensin I/metabolism* ; Heart Failure ; Humans ; Peptide Fragments/metabolism* ; Ventricular Remodeling

To investigate changes in the angiotensin converting enzyme 2 (ACE2) and angiotensin (1-7) [Ang (1-7)] and to explore the role of ACE2-Ang (1-7)-Mas receptor axis in hypertension with heart failure with preserved ejection fraction (HFPEF).
 Methods: A total of 70 patients with primary hypertension and preserved left ventricular ejection fraction (LVEF>50%) were recruited and patients were divided into a hypertension group (HBP) and a heart failure with preserved ejection fraction group (HFpEF) according to the diagnostic criteria of HFpEF. Thirty-five healthy participants were selected randomly as a control group. Enzyme linked immunosorbent assays (ELISA) method was used to detect concentration of Ang (1-7), ACE2, angiotensin II (Ang II), brain natriuretic peptide (BNP) in plasma. Male Sprague- Dawley (SD) rats was randomly divided into 2 groups: An HFpEF group (n=16) and a sham group (n=8). Rats (n=8) in the AAC group were given Ang (1-7) [0.5 mg/(kg.d), intraperitoneally] for 6 weeks, and the rest were given equal dose normal saline. Then all the rats were killed, and the hearts were taken out for hematoxylineosin (HE) staining. The protein expressions of angiotensin converting enzyme (ACE), ACE2, and Mas receptor were detected by Western blot.
 Results: The BNP and Ang II were significantly increased in the HBP group and the HFpEF group compared with the control group (P<0.01). There were not significantly different in levels of ACE2 and Ang (1-7) between the HBP group and control group (P>0.05), whereas those levels were significantly increased in the HFpEF group compared with the HBP group and control group (P<0.01). HE staining showed obvious hypertrophy of myocardial cell in the AAC group compared with the sham group. Hypertrophy of myocardial cell in the AAC+Ang (1-7) group was significantly higher than that in the AAC group. Expressions of ACE, ACE2, and Mas receptor proteins were significantly higher in the AAC group than those in the sham group (P<0.05), while the expressions of ACE2 and Mas receptor proteins in the AAC+Ang (1-7) group were significantly higher than those in the AAC group (P<0.05). There was no significant difference in the ACE protein expression between groups (P>0.05).
 Conclusion: ACE2 and Ang (1-7) are important predictive factors for the severity of heart failure and myocardial remodeling of HFpEF with hypertension; ACE2-Ang (1-7)-Mas receptor axis may play a protective role in preventing myocardial remodeling in HFpEF with hypertension.
Angiotensin I ; physiology ; Angiotensin II ; Animals ; Atrial Remodeling ; physiology ; Case-Control Studies ; Enzyme-Linked Immunosorbent Assay ; Heart Failure ; metabolism ; physiopathology ; Humans ; Hypertension ; metabolism ; physiopathology ; Male ; Peptide Fragments ; physiology ; Peptidyl-Dipeptidase A ; physiology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; physiology ; Stroke Volume ; Ventricular Function, Left ; physiology ; Ventricular Remodeling ; physiology

Animals ; Cell Respiration ; Electron Transport Complex III ; metabolism ; Humans ; Iron-Sulfur Proteins ; chemistry ; metabolism ; Mitochondria ; metabolism ; Peptide Fragments ; chemistry ; metabolism ; Protein Multimerization ; Protein Structure, Quaternary ; Protein Subunits ; chemistry