Proteomic studies of VEGFR2 in human placentas reveal protein associations with preeclampsia, diabetes, gravidity, and labor.

VEGFR2 (Vascular endothelial growth factor receptor 2) is a central regulator of placental angiogenesis. The study of the VEGFR2 proteome of chorionic villi at term revealed its partners MDMX (Double minute 4 protein) and PICALM (Phosphatidylinositol-binding clathrin assembly protein). Subsequently, the oxytocin receptor (OT-R) and vasopressin V1aR receptor were detected in MDMX and PICALM immunoprecipitations. Immunogold electron microscopy showed VEGFR2 on endothelial cell (EC) nuclei, mitochondria, and Hofbauer cells (HC), tissue-resident macrophages of the placenta. MDMX, PICALM, and V1aR were located on EC plasma membranes, nuclei, and HC nuclei. Unexpectedly, PICALM and OT-R were detected on EC projections into the fetal lumen and OT-R on 20-150 nm clusters therein, prompting the hypothesis that placental exosomes transport OT-R to the fetus and across the blood-brain barrier. Insights on gestational complications were gained by univariable and multivariable regression analyses associating preeclampsia with lower MDMX protein levels in membrane extracts of chorionic villi, and lower MDMX, PICALM, OT-R, and V1aR with spontaneous vaginal deliveries compared to cesarean deliveries before the onset of labor. We found select associations between higher MDMX, PICALM, OT-R protein levels and either gravidity, diabetes, BMI, maternal age, or neonatal weight, and correlations only between PICALM-OT-R (p < 2.7 × 10-8), PICALM-V1aR (p < 0.006), and OT-R-V1aR (p < 0.001). These results offer for exploration new partnerships in metabolic networks, tissue-resident immunity, and labor, notably for HC that predominantly express MDMX.

HK2 and LDHA upregulation mediate hexavalent chromium-induced carcinogenesis, cancer development and prognosis through miR-218 inhibition.

Hexavalent chromium [Cr(VI)] is one of the most common environmental contaminants due to its tremendous industrial applications, but its effects and mechanism remain to be investigated. Our previous studies showed that Cr(VI) exposure caused malignant transformation and tumorigenesis. This study showed that glycolytic proteins HK2 and LDHA levels were statistically significant changed in blood samples of Cr(VI)-exposed workers and in Cr-T cells compared to the control subjects and parental cells. HK2 and LDHA knockdown inhibited cell proliferation and angiogenesis, and higher HK2 and LDHA expression levels are associated with advanced stages and poor prognosis of lung cancer. We found that miR-218 levels were significantly decreased and miR-218 directly targeted HK2 and LDHA for inhibiting their expression. Overexpression of miR-218 inhibited glucose consumption and lactate production in Cr-T cells. Further study found that miR-218 inhibited tumor growth and angiogenesis by decreasing HK2 and LDHA expression in vivo. MiR-218 levels were negatively correlated with HK2 and LDHA expression levels and cancer development in human lung and other cancers. These results demonstrated that miR-218/HK2/LDHA pathway is vital for regulating Cr(VI)-induced carcinogenesis and human cancer development.

Unnatural helical peptidic foldamers as protein segment mimics.

Unnatural helical peptidic foldamers have attracted considerable attention owing to their unique folding behaviours, diverse artificial protein binding mechanisms, and promising applications in chemical, biological, medical, and material fields. Unlike the conventional α-helix consisting of molecular entities of native α-amino acids, unnatural helical peptidic foldamers are generally comprised of well-defined backbone conformers with unique and unnatural structural parameters. Their folded structures usually arise from unnatural amino acids such as N-substituted glycine, N-substituted-ß-alanine, ß-amino acid, urea, thiourea, α-aminoxy acid, α-aminoisobutyric acid, aza-amino acid, aromatic amide, γ-amino acid, as well as sulfono-γ-AA amino acid. They can exhibit intriguing and predictable three-dimensional helical structures, generally featuring superior resistance to proteolytic degradation, enhanced bioavailability, and improved chemodiversity, and are promising in mimicking helical segments of various proteins. Although it is impossible to include every piece of research work, we attempt to highlight the research progress in the past 10 years in exploring unnatural peptidic foldamers as protein helical segment mimics, by giving some representative examples and discussing the current challenges and future perspectives. We expect that this review will help elucidate the principles of structural design and applications of existing unnatural helical peptidic foldamers in protein segment mimicry, thereby attracting more researchers to explore and generate novel unnatural peptidic foldamers with unique structural and functional properties, leading to more unprecedented and practical applications.

The efficacy of electroacupuncture in among early diabetic patients with lower limb arteriosclerotic wounds.

Diabetic foot ulcers are the prevalent complication of diabetes mellitus, frequently culminating in arteriosclerosis of the lower extremities and consequent development of chronic wounds. The effectiveness of electroacupuncture (EA) as therapeutic intervention for promoting wound healing in this particular group of patients has been comprehensively assessed in this study. A randomized controlled trial involving 380 early diabetic patients with arteriosclerotic lesions of the lower limbs was conducted. Standard wound care plus EA was administered to the treatment group, while standard wound care alone was administered to the control group. The principal outcome assessed was the reduction in lesion size following the 8-week treatment period. Pain scores, recuperation time, and quality of life (QoL) evaluations constituted secondary outcomes. In comparison to the control group, the treatment group exhibited a significantly greater reduction in wound size (p < 0.05). The treatment group exhibited significantly reduced pain scores and significantly higher QoL scores (p < 0.05). The duration of recovery did not vary substantially among the groups (p > 0.05). Electroacupuncture thus appeared to be an effective adjunctive treatment for early diabetic patients with lower limb arteriosclerotic lesions, promoting pain relief and quality of life. Additional investigation is necessary to validate these results and delve into the underlying mechanisms of action.

Inhibition of Hypoxia-Inducible Transcription Factor (HIF-1α) Signaling with Sulfonyl-γ-AApeptide Helices.

The development of inhibitors that selectively block protein-protein interactions (PPIs) is crucial for chemical biology, medicinal chemistry, and biomedical sciences. Herein, we reported the design, synthesis, and investigation of sulfonyl-γ-AApeptide as an alternative strategy of canonical peptide-based inhibitors to disrupt hypoxia-inducible factor 1α (HIF-1α) and p300 PPI by mimicking the helical domain of HIF-1α involved in the binding to p300. The designed molecules recognized the p300 protein with high affinity and potently inhibited the hypoxia-inducible signaling pathway. Gene expression profiling supported the idea that the lead molecules selectively inhibited hypoxia-inducible genes involved in the signaling cascade. Our studies also demonstrated that both helical faces consisting of either chiral side chains or achiral sulfonyl side chains of sulfonyl-γ-AApeptides could be adopted for mimicry of the α-helix engaging in PPIs. Furthermore, these sulfonyl-γ-AApeptides were cell-permeable and exhibited favorable stability and pharmacokinetic profiles. Our results could inspire the design of helical sulfonyl-γ-AApeptides as a general strategy to mimic the protein helical domain and modulate many other PPIs.

Deciphering gp120 sequence variation and structural dynamics in HIV neutralization phenotype by molecular dynamics simulations and graph machine learning.

Human immunodeficiency virus (HIV) exploits the sequence variation and structural dynamics of the envelope glycoprotein gp120 to evade the immune attack of neutralization antibodies, contributing to various HIV neutralization phenotypes. Although the HIV neutralization phenotype has been experimentally characterized, the roles of rapid sequence variability and significant structural dynamics of gp120 are not well understood. Here, 45 prefusion gp120 from different HIV strains belong to three tiers of sensitive, moderate, and resistant neutralization phenotype are structurally modeled by homology modeling and then investigated by molecular dynamics (MD) simulations and graph machine learning (ML). Our results show that the structural deviations, population distribution, and conformational flexibility of gp120 are related to the HIV neutralization phenotype. Per-residue dynamics indicate the local regions especially in the second structural elements with high-flexibility, may be responsible for the HIV neutralization phenotype. Moreover, a graph ML model with the attention mechanism was trained to explore inherent representation related to the classification of the HIV neutralization phenotype, further distinguishing the strong related gp120 sequence variation together with structural dynamics in the HIV neutralization phenotype. Our study not only deciphers gp120 sequence variation and structural dynamics in the HIV neutralization phenotype but also explores complex relationships between the sequence, structure, and dynamics of protein by combining MD simulations and ML.

Modulating Angiogenesis by Proteomimetics of Vascular Endothelial Growth Factor.

Angiogenesis, formation of new blood vessels from the existing vascular network, is a hallmark of cancer cells that leads to tumor vascular proliferation and metastasis. This process is mediated through the binding interaction of VEGF-A with VEGF receptors. However, the balance between pro-angiogenic and anti-angiogenic effect after ligand binding yet remains elusive and is therefore challenging to manipulate. To interrogate this interaction, herein we designed a few sulfono-γ-AA peptide based helical peptidomimetics that could effectively mimic a key binding interface on VEGF (helix-α1) for VEGFR recognition. Intriguingly, although both sulfono-γ-AA peptide sequences V2 and V3 bound to VEGF receptors tightly, in vitro angiogenesis assays demonstrated that V3 potently inhibited angiogenesis, whereas V2 activated angiogenesis effectively instead. Our findings suggested that this distinct modulation of angiogenesis might be due to the result of selective binding of V2 to VEGFR-1 and V3 to VEGFR-2, respectively. These molecules thus provide us a key to switch the angiogenic signaling, a biological process that balances the effects of pro-angiogenic and anti-angiogenic factors, where imbalances lead to several diseases including cancer. In addition, both V2 and V3 exhibited remarkable stability toward proteolytic hydrolysis, suggesting that V2 and V3 are promising therapeutic agents for the intervention of disease conditions arising due to angiogenic imbalances and could also be used as novel molecular switching probes to interrogate the mechanism of VEGFR signaling. The findings also further demonstrated the potential of sulfono-γ-AA peptides to mimic the α-helical domain for protein recognition and modulation of protein-protein interactions.

Inhibition of ß-catenin/B cell lymphoma 9 protein-protein interaction using α-helix-mimicking sulfono-γ-AApeptide inhibitors.

The rational design of α-helix-mimicking peptidomimetics provides a streamlined approach to discover potent inhibitors for protein-protein interactions (PPIs). However, designing cell-penetrating long peptidomimetic scaffolds equipped with various functional groups necessary for interacting with large protein-binding interfaces remains challenging. This is particularly true for targeting ß-catenin/BCL9 PPIs. Here we designed a series of unprecedented helical sulfono-γ-AApeptides that mimic the binding mode of the α-helical HD2 domain of B Cell Lymphoma 9 (BCL9). Our studies show that sulfono-γ-AApeptides can structurally and functionally mimic the α-helical domain of BCL9 and selectively disrupt ß-catenin/BCL9 PPIs with even higher potency. More intriguingly, these sulfono-γ-AApeptides can enter cancer cells, bind with ß-catenin and disrupt ß-catenin/BCL9 PPIs, and exhibit excellent cellular activity, which is much more potent than the BCL9 peptide. Furthermore, our enzymatic stability studies demonstrate the remarkable stability of the helical sulfono-γ-AApeptides, with no degradation in the presence of pronase for 24 h, augmenting their biological potential. This work represents not only an example of helical sulfono-γ-AApeptides that mimic α-helix and disrupt protein-protein interactions, but also an excellent example of potent, selective, and cell-permeable unnatural foldameric peptidomimetics that disrupt the ß-catenin/BCL9 PPI. The design of helical sulfono-γ-AApeptides may lead to a new strategy to modulate a myriad of protein-protein interactions.

Electrostatic Interactions Are the Primary Determinant of the Binding Affinity of SARS-CoV-2 Spike RBD to ACE2: A Computational Case Study of Omicron Variants.

To explore the mechanistic origin that determines the binding affinity of SARS-CoV-2 spike receptor binding domain (RBD) to human angiotensin converting enzyme 2 (ACE2), we constructed the homology models of RBD-ACE2 complexes of four Omicron subvariants (BA.1, BA.2, BA.3 and BA.4/5), and compared them with wild type complex (RBDWT-ACE2) in terms of various structural dynamic properties by molecular dynamics (MD) simulations and binding free energy (BFE) calculations. The results of MD simulations suggest that the RBDs of all the Omicron subvariants (RBDOMIs) feature increased global structural fluctuations when compared with RBDWT. Detailed comparison of BFE components reveals that the enhanced electrostatic attractive interactions are the main determinant of the higher ACE2-binding affinity of RBDOMIs than RBDWT, while the weakened electrostatic attractive interactions determine RBD of BA.4/5 subvariant (RBDBA.4/5) lowest ACE2-binding affinity among all Omicron subvariants. The per-residue BFE decompositions and the hydrogen bond (HB) networks analyses indicate that the enhanced electrostatic attractive interactions are mainly through gain/loss of the positively/negatively charged residues, and the formation or destruction of the interfacial HBs and salt bridges can also largely affect the ACE2-binding affinity of RBD. It is worth pointing out that since Q493R plays the most important positive contribution in enhancing binding affinity, the absence of this mutation in RBDBA.4/5 results in a significantly weaker binding affinity to ACE2 than other Omicron subvariants. Our results provide insight into the role of electrostatic interactions in determining of the binding affinity of SARS-CoV-2 RBD to human ACE2.

Sulfono-γ-AApeptides as Helical Mimetics: Crystal Structures and Applications.

Foldamers have defined and predictable structures, improved resistance to proteolytic degradation, enhanced chemical diversity, and are versatile in their mimicry of biological molecules, making them promising candidates in biomedical and material applications. However, as natural macromolecules exhibit endless folding structures and functions, the exploration of the applications of foldamers remains crucial. As such, it is imperative to continue to discover unnatural foldameric architectures with new frameworks and molecular scaffolds. To this end, we recently developed a new class of peptidomimetics termed ″γ-AApeptides", oligomers of γ-substituted-N-acylated-N-aminoethyl amino acids, which are inspired by the chiral peptide nucleic acid backbone. To date γ-AApeptides have been shown to be resistant to proteolytic degradation and possess limitless potential to introduce chemically diverse functional groups, demonstrating promise in biomedical and material sciences. However, the structures of γ-AApeptides were initially unknown, rendering their rational design for the mimicry of a protein helical domain impossible in the beginning, which limited their potential development. To our delight, in the past few years, we have obtained a series of crystal structures of helical sulfono-γ-AApeptides, a subclass of γ-AApeptides. The single-crystal X-ray crystallography indicates that sulfono-γ-AApeptides fold into unprecedented and well-defined helices with unique helical parameters. On the basis of the well-established size, shape, and folding conformation, the design of sulfono-γ-AApeptide-based foldamers opens a new avenue for the development of alternative unnatural peptidomimetics for their potential applications in chemistry, biology, medicine, materials science, and so on.In this Account, we will outline our journey on sulfono-γ-AApeptides and their application as helical mimetics. We will first briefly introduce the design and synthetic strategy of sulfono-γ-AApeptides and then describe the crystal structures of helical sulfono-γ-AApeptides, including left-handed homogeneous sulfono-γ-AApeptides, right-handed 1:1 α/sulfono-γ-AA peptide hybrids, and right-handed 2:1 α/sulfono-γ-AA peptide hybrids. After that, we will illustrate the potential of helical sulfono-γ-AApeptides for biological applications such as the disruption of medicinally relevant protein-protein interactions (PPIs) of BCL9-ß-catenin and p53-MDM2/MDMX as well as the mimicry of glucagon-like peptide 1 (GLP-1). In addition, we also exemplify their potential application in material science. We expect that this Account will shed light on the structure-based design and function of helical sulfono-γ-AApeptides, which can provide a new and alternative way to explore and generate novel foldamers with distinctive structural and functional properties.

Quadriceps strength and knee joint function in patients with severe knee extension contracture following arthroscopic-assisted mini-incision quadricepsplasty.

PURPOSE: To evaluate reserve quadriceps function and improve knee activity in patients with severe knee extension contracture following arthroscopic-assisted mini-incision quadricepsplasty as well as post-operative complications. METHODS: From 2012 to 2019, 32 patients with severe knee extension contractures (less than 45° range of flexion) were treated with an all-arthroscopic release technique. The clinical results, including range of motion (ROM), quadriceps function (quadriceps index, QI), and knee function, were evaluated, and MRI of the healed tendon after partial quadricepsplasty was performed. The patellar track and length during knee flexion were measured on three normal knees under fluoroscopy. Three formalin-fixed lower limbs were used to mimic severely contracted quadriceps to evaluate the extension of the patellar track. RESULTS: The median follow-up time was 2.1 years (1-5 years). The average QI was 92.0 ± 6.2, and the quadriceps muscle strength was increased from 3.28 to 4.72. At the final follow-up, 90% of the patients had no difficulty going upstairs, going downstairs, or rising from a chair. The ROM improved by 25.69 ± 3.6 preoperatively to 105.88 ± 6.6 at the final follow-up (P < 0.001). The open surgery showed that a 2-cm extension could be achieved by partly cutting the quadriceps tendon, and two cuts achieved a total extension of 5.2 ± 0.52 cm. The patellar tracking distance was 7.7 ± 0.43 cm, and the gap between the patella and femur was also reduced. CONCLUSION: Partial quadricepsplasty of the rectus femoris extended the contracted quadriceps and maintained quadriceps strength, allowing for full knee flexion and satisfactory clinical outcomes of knee function with few complications.

Rational Design and Synthesis of Right-Handed d-Sulfono-γ-AApeptide Helical Foldamers as Potent Inhibitors of Protein-Protein Interactions.

Novel unprecedented helical foldamers have been effectively designed and synthesized. The homogeneous right-handed d-sulfono-γ-AApeptides represent a new generation of unnatural helical peptidomimetics, which have similar folding conformation to α-peptides, making them an ideal molecular scaffold to design α-helical mimetics. As demonstrated with p53-MDM2 PPI as a model application, the right-handed d-sulfono-γ-AApeptides reveal much-enhanced binding affinity compared to the p53 peptide. The design of d-sulfono-γ-AApeptides may provide a new and alternative strategy to modulate protein-protein interactions.

Characterization of a Cu2+, SDS, alcohol and glucose tolerant GH1 ß-glucosidase from Bacillus sp. CGMCC 1.16541.

A ß-glucosidase gene (bsbgl1a) from Bacillus sp. CGMCC 1.16541 was expressed in Escherichia coli BL21 and subsequently characterized. The amino acid sequence shared 83.64% identity with ß-glucosidase (WP_066390903.1) from Fictibacillus phosphorivorans. The recombinant ß-glucosidase (BsBgl1A) had a molecular weight of 52.2 kDa and could hydrolyze cellobiose, cellotriose, cellotetrose, p-nitrophenyl-ß-D-glucopyranoside (pNPG), and p-nitrophenyl-ß-D-xylopyranoside (pNPX). Optimal activity for BsBgl1A was recorded at 45 °C with a pH between 5.6 and 7.6, and 100% of its activity was maintained after a 24 h incubation between pH 4 and 9. Kinetic characterization revealed an enzymatic turnover (Kcat) of 616 ± 2 s-1 (with cellobiose) and 3.5 ± 0.1 s-1 (with p-nitrophenyl-ß-D-glucopyranoside). Interestingly, the recombinant enzyme showed cupric ion (Cu2+), sodium dodecyl sulfate (SDS) and alcohol tolerance at 10 mM for Cu2+ and 10% for both SDS and alcohol. Additionally, BsBgl1A had high tolerance for glucose (Ki = 2095 mM), which is an extremely desirable feature for industrial applications. Following the addition of BsBgl1A (0.05 mg/ml) to a commercial cellulase reaction system, glucose yields from sugarcane bagasse increased 100% after 1 day at 45 °C. This work identifies a Cu2+, SDS, alcohol, and glucose tolerant GH1 ß-glucosidase with potential applications in the hydrolysis of cellulose for the bioenergy industry.

The CEACAM1-derived peptide QLSN impairs collagen-induced human platelet activation through glycoprotein VI.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates collagen-mediated platelet activation through its cytoplasmic immunoreceptor tyrosine-based inhibition motifs (ITIMs). However, the function of CEACAM1's extracellular cleavage fragments is currently unknown. In the present study, we used mass spectrometry (MS) to identify 9 cleavage fragments shed by matrix metallopeptidase 12 (MMP-12), and then we synthesized peptides with sequences corresponding to the fragments. QLSNGNRTLT (QLSN), a peptide from the A1-domain of CEACAM1, significantly attenuated collagen-induced platelet aggregation. QLSN also attenuated platelet static adhesion to collagen. Additionally, QLSN reduced human platelet secretion and integrin αIIbß3 activation in response to glycoprotein VI (GPVI)-selective agonist, convulxin. Correspondingly, QLSN treatment significantly decreased convulxin-mediated phosphorylation of Src, protein kinase B (Akt), spleen tyrosine kinase (Syk) and phospholipase Cγ2 (PLCγ2) in human platelets. These data indicate that the CEACAM1-derived peptide QLSN inhibits GPVI-mediated human platelet activation. QLSN could potentially be developed as a novel antiplatelet agent.

New Insight into Mechanisms of Protein Adaptation to High Temperatures: A Comparative Molecular Dynamics Simulation Study of Thermophilic and Mesophilic Subtilisin-Like Serine Proteases.

In high-temperature environments, thermophilic proteins must possess enhanced thermal stability in order to maintain their normal biological functions. However, the physicochemical basis of the structural stability of thermophilic proteins at high temperatures remains elusive. In this study, we performed comparative molecular dynamics simulations on thermophilic serine protease (THM) and its homologous mesophilic counterpart (PRK). The comparative analyses of dynamic structural and geometrical properties suggested that THM adopted a more compact conformation and exhibited more intramolecular interactions and lower global flexibility than PRK, which could be in favor of its thermal stability in high-temperature environments. Comparison between protein solvent interactions and the hydrophobicity of these two forms of serine proteases showed that THM had more burial of nonpolar areas, and less protein solvent hydrogen bonds (HBs), indicating that solvent entropy maximization and mobility may play a significant role in THM's adaption to high temperature environments. The constructed funnel-like free energy landscape (FEL) revealed that, in comparison to PRK, THM had a relatively flat and narrow free energy surface, and a lower minimum free energy level, suggesting that the thermophilic form had lower conformational diversity and flexibility. Combining the FEL theory and our simulation results, we conclude that the solvent (entropy force) plays a significant role in protein adaption at high temperatures.

Helical Sulfono-γ-AApeptides with Aggregation-Induced Emission and Circularly Polarized Luminescence.

Aggregation-induced emission (AIE) was intensively studied because of packing of small molecules and polymers; however, mid-molecular-weight (1000-3000) molecular scaffold containing a precise number of AIE luminogens is rare. Herein, we report the investigation of three tetraphenylethylene (TPE)-modified sulfono-γ-AApeptides in which multiple TPE moieties are conjugated to the chiral right-handed helical peptidomimetic backbone as functional side chains. The crystal structure of the TPE-α/sulfono-γ-AA peptide 1 demonstrates that because of the rigid helical scaffold of the TPE-α/sulfono-γ-AA peptides, the intramolecular rotations of the TPE with short linker are restricted, therefore leading to the boosted fluorescent emission in solution. Peptides 2 and 3 exhibit aggregation-induced emission enhancement (AIEE), possibly because of the combination of both AIE and rotation restriction. Moreover, because of their preoriented assembly induced by the right-handed helical scaffold, these emissive chiral luminogens show effective circularly polarized luminescence signals with high dissymmetry factor glum. Finally, the amphiphilic nature of TPE-α/sulfono-γ-AA peptides could enable them to penetrate the bacterial membranes and exhibit strong fluorescence. Their antimicrobial activity and labeling-free character could further augment their potential applications in both materials and biomedical sciences.

All-arthroscopic release for treating severe knee extension contractures could improve the knee range of motion and the mid-term functional outcomes.

PURPOSE: To evaluate the safety, feasibility, and effectiveness of an all-arthroscopic technique for the intra- and extraarticular release of severe knee extension contractures. METHODS: From 2012 to 2016, 25 patients with severe knee extension contractures (less than 45° range of flexion) were treated with an all-arthroscopic release technique. The patients underwent intra- and extraarticular arthroscopic release and arthroscopic-assisted mini-incision quadriceps plasty. The post-operative rehabilitation was initiated the first day after the procedures. Comprehensive clinical follow-up evaluations including the range-of-motion (ROM) assessment, the Lysholm score, and the International Knee Documentation Committee (IKDC) score were performed on all patients. RESULTS: The median follow-up time was 28 months (range 12-65 months). The ROM improved from 23.9° ± 7.5° pre-operatively to 105.9° ± 6.5° at the final follow-up (P < 0.001). In addition, the Lysholm score increased from 59.9 ± 5.2 pre-operatively to 89.7 ± 3.3 (P < 0.001). The IKDC score increased from 47.6 ± 3.4 pre-operatively to 91.7 ± 2.4 (P < 0.001). All patients were satisfied with their final ROM and functional outcomes. CONCLUSION: The all-arthroscopic release technique was a safe, feasible and effective method for treating severe knee extension contractures. The severe knee extension contractures may be successfully addressed by the all-arthroscopic release technique during our clinical practice. LEVEL OF EVIDENCE: IV.

Effects of CD4 Binding on Conformational Dynamics, Molecular Motions, and Thermodynamics of HIV-1 gp120.

Human immunodeficiency virus type-1 (HIV-1) infection is triggered by its envelope (Env) glycoprotein gp120 binding to the host-cell receptor CD4. Although structures of Env/gp120 in the liganded state are known, detailed information about dynamics of the liganded gp120 has remained elusive. Two structural models, the CD4-free gp120 and the gp120-CD4 complex, were subjected to µs-scale multiple-replica molecular dynamics (MD) simulations to probe the effects of CD4 binding on the conformational dynamics, molecular motions, and thermodynamics of gp120. Comparative analyses of MD trajectories in terms of structural deviation and conformational flexibility reveal that CD4 binding effectively suppresses the overall conformational fluctuations of gp120. Despite the largest fluctuation amplitude of the V1/V2 region in both forms of gp120, the presence of CD4 prevents it from approaching the gp120 core. Comparison of the constructed free energy landscapes (FELs) shows that CD4 binding reduces the conformational entropy and conformational diversity while enhancing the stability of gp120. Further comparison of the representative structures extracted from free energy basins/minima of FELs reveals that CD4 binding weakens the reorientation ability of V1/V2 and hence hinders gp120 from transitioning out of the liganded state to the unliganded state. Therefore, locking gp120 conformation via restraining V1/V2 reorientation with small molecules seems to be a promising strategy to control HIV-1 infection. Our computer simulation results support the conformational selection mechanism for CD4 binding to gp120 and facilitate the understanding of HIV-1 immune evasion mechanisms.

Hydrogen-Bonding-Driven 3D Supramolecular Assembly of Peptidomimetic Zipper.

Hydrogen-bonding-driven three-dimensional (3D) assembly of a peptidomimetic zipper has been established for the first time by using an α/AApeptide zipper that assembles into a de novo lattice arrangement through two layers of hydrogen-bonded linker-directed interactions. Via a covalently bridged 1D 413-helix, drastic enhancement in stability has been achieved in the formed 3D crystalline supramolecular architecture as evidenced by gas-sorption studies. As the first example of an unnatural peptidic zipper, the dimensional augmentation of the zipper differs from metal-coordinated strategies, and may have general implications for the preparation of peptidic functional materials for a variety of future applications.

Association of matrix metalloprotease 1, 3, and 12 polymorphisms with rheumatic heart disease in a Chinese Han population.

BACKGROUND: Rheumatic heart disease (RHD) is an autoimmune disease triggered by acute rheumatic fever (ARF). Matrix metalloproteinases (MMPs) play an important role in the modulation of immune responses. The purpose of this study was to evaluate the association of MMP1, 3, and 12 promoter polymorphisms with RHD in a Han population in Southern China since the 3 genes are localized on the same chromosome and have a combined effect. METHODS: DNA samples were obtained from 90 adult patients with RHD and 90 control subjects. Polymorphisms in MMP1 (rs1799750), MMP3 (rs3025058), and MMP12 (rs2276109) were genotyped by direct sequencing. Differences in genotype and allele frequencies of these polymorphisms were compared between the cases and the controls using Unconditional logistic regression models and Chi-squared test. RESULTS: The 2G/2G genotype of rs1799750 in MMP1 was associated with a significantly higher risk of RHD when compared with the 1G/1G genotype (OR = 3.227; 95% CI:1.118-9.31; p = 0.03). The frequency of allele 2G was higher in patients with RHD compared to the controls (69.4% vs. 58.9%; p = 0.048) No significant differences in genotype and allele frequencies of rs3025058 in MMP3 and rs2276109 in MMP12 were found between the patients with RHD and the controls (p > 0.05). CONCLUSIONS: Our results suggest that rs1799750 in MMP1 might be a risk factor for RHD in a Han population in Southern China, and individuals carrying the 2G/2G genotype are likely more susceptible to RHD. In contrast, rs3025058 in MMP3 and rs2276109 in MMP12 might not contribute to the risk of developing RHD in this population. Further studies with larger samples and other ethnic populations are required to confirm these findings.