Female age affects the utility of sperm DNA fragmentation in predicting IVF and ICSI outcomes.

RESEARCH QUESTION: The aim of this study was to investigate how female age affects the predictive effect of sperm DNA fragmentation index (DFI) on clinical outcomes with assisted reproductive technology. DESIGN: A total of 2371 patients, comprising 2115 men with a normal DFI (≤30), 256 men with a high DFI (>30) and women of different ages, were recruited and investigated. All patients had normal chromosome karyotypes and were undergoing their first fresh IVF or intracytoplasmic sperm injection (ICSI) cycles. Clinical outcomes were analysed according to the two DFI groups and female age ≤30 and >30 years. Binary logistic regression analysis was performed to identify factors associated with clinical outcome. RESULTS: The proportion of couples with at least one good-quality embryo in the DFI ≤30 group was higher than that in the DFI >30 group. When female age exceeded 30 years, clinical pregnancy rate and the proportion of couples with good-quality embryos in the DFI >30 group were lower compared with DFI ≤30; however, there were no differences in outcomes for female age ≤30 years according to DFI. When DFI >30, the cut-off value of female age was 30.5 for detecting clinical pregnancy; the sensitivity was 62.0%, and the specificity was 63.6%. Clinical pregnancy rate and proportion of couples with good-quality embryos were lower in the DFI >30 versus DFI ≤30 group with a female age above 30 years for IVF but not for ICSI. CONCLUSION: Female age has a negative effect and should be considered in predicting the effects of sperm DNA fragmentation on pregnancy outcomes.

Antifungal effect and action mechanism of antimicrobial peptide polybia-CP.

The incidence of life-threatening invasive fungal infections increased significantly in recent years. However, the antifungal therapeutic options are very limited. Antimicrobial peptides are a class of potential lead chemical for the development of novel antifungal agents. Antimicrobial peptide polybia-CP was purified from the venom of the social wasp Polybia paulista. In this study, we synthesized polybia-CP and determined its antifungal effects against a series of Candidian species. Our results showed that polybia-CP has potent antifungal activity and fungicidal activity against the tested fungal cells with a proposed membrane-active action mode. In addition, polybia-CP could induce the increase of cellular reactive oxygen species production, which would attribute to its antifungal activity. In conclusion, the present study suggests that polybia-CP has potential as an antifungal agent or may offer a new strategy for antifungal therapeutic option.

Quercetin inhibits human sperm functions by reducing sperm [Ca2+]i and tyrosine phosphorylation.

Quercetin is widely known as potent natural antioxidant and scavenger of reactive oxygen species (ROS) and nitric oxide both in vitro and in vivo. Quercetin has a wide range of biological functions and health-promoting effects. There are more and more interests in the addition of this flavonol to various traditional food products. However, the in vitro toxicity of quercetin to mature human sperm remains unknown. In this study, we investigated the in vitro effects of quercetin on human sperm functions. The results showed that the total sperm motility were significantly inhibited compared to the controls following exposure to 100, 200 and 400µM quercetin for 6 and 12h; quercetin did not affect human sperm viability. The acrosome reaction and capacitation induced by progesterone were dose-dependently inhibited by quercetin. Furthermore, quercetin induced a significantly decrease of human sperm [Ca2+]i after 2 min above 50 µM, and dose-dependently decreased the protein-tyrosine phosphorylation of human sperm. Our results indicated that quercetin may decrease sperm [Ca2+]i, suppresse tyrosine phosphorylation, and subsequently inhibit sperm functions.

Antimicrobial activities and membrane-active mechanism of CPF-C1 against multidrug-resistant bacteria, a novel antimicrobial peptide derived from skin secretions of the tetraploid frog Xenopus clivii.

Hospital-acquired infections caused by multidrug-resistant bacteria pose significant challenges for treatment, which necessitate the development of new antibiotics. Antimicrobial peptides are considered potential alternatives to conventional antibiotics. The skin of Anurans (frogs and toads) amphibians is an extraordinarily rich source of antimicrobial peptides. CPF-C1 is a typical cationic antimicrobial peptide that was originally isolated from the tetraploid frog Xenopus clivii. Our results showed that CPF-C1 has potent antimicrobial activity against both sensitive and multidrug-resistant bacteria. It disrupted the outer and inner membranes of bacterial cells. CPF-C1 induced both propidium iodide uptake into the bacterial cell and the leakage of calcein from large liposome vesicles, which suggests a mode of action that involves membrane disturbance. Scanning electron microscopy and transmission electron microscopy verified the morphologic changes of CPF-C1-treated bacterial cells and large liposome vesicles. The membrane-dependent mode of action signifies that the CPF-C1 peptide functions freely and without regard to conventional resistant mechanisms. Additionally, it is difficult for bacteria to develop resistance against CPF-C1 under this action mode. Other studies indicated that CPF-C1 had low cytotoxicity against mammalian cell. In conclusion, considering the increase in multidrug-resistant bacterial infections, CPF-C1 may offer a new strategy that can be considered a potential therapeutic agent for the treatment of diseases caused by multidrug-resistant bacteria.

Causality-Invariant Interactive Mining for Cross-Modal Similarity Learning.

In the real world, how to effectively learn consistent similarity measurement across different modalities is essential. Most of the existing similarity learning methods cannot deal well with cross-modal data due to the modality gap and have obvious performance degeneration when applied to cross-modal data. To tackle this problem, we propose a novel cross-modal similarity learning method, called Causality-Invariant Interactive Mining (CIIM), that can effectively capture informative relationships among different samples and modalities to derive the modality-consistent feature embeddings in the unified metric space. Our CIIM tackles the modality gap from two aspects, i.e., sample-wise and feature-wise. Specifically, we start from the sample-wise view and learn the single-modality and hybrid-modality proxies for exploring the cross-modal similarity with the elaborate metric losses. In this way, sample-to-sample and sample-to-proxy correlations are both taken into consideration. Furthermore, we conduct the causal intervention to eliminate the modality bias and reconstruct the invariant causal embedding in the feature-wise aspect. To this end, we force the learned embeddings to satisfy the specific properties of our causal mechanism and derive the causality-invariant feature embeddings in the unified metric space. Extensive experiments on two cross-modality tasks demonstrate the superiority of our proposed method over the state-of-the-art methods.

The m6A reader IGF2BP2 regulates glycolytic metabolism and mediates histone lactylation to enhance hepatic stellate cell activation and liver fibrosis.

Evidence for the involvement of N6-Methyladenosine (m6A) modification in the etiology and progression of liver fibrosis has emerged and holds promise as a therapeutic target. Insulin-like growth factor 2 (IGF2) mRNA-binding protein 2 (IGF2BP2) is a newly identified m6A-binding protein that functions to enhance mRNA stability and translation. However, its role as an m6A-binding protein in liver fibrosis remains elusive. Here, we observed that IGF2BP2 is highly expressed in liver fibrosis and activated hepatic stellate cells (HSCs), and inhibition of IGF2BP2 protects against HSCs activation and liver fibrogenesis. Mechanistically, as an m6A-binding protein, IGF2BP2 regulates the expression of Aldolase A (ALDOA), a key target in the glycolytic metabolic pathway, which in turn regulates HSCs activation. Furthermore, we observed that active glycolytic metabolism in activated HSCs generates large amounts of lactate as a substrate for histone lactylation. Importantly, histone lactylation transforms the activation phenotype of HSCs. In conclusion, our findings reveal the essential role of IGF2BP2 in liver fibrosis by regulating glycolytic metabolism and highlight the potential of targeting IGF2BP2 as a therapeutic for liver fibrosis.

Two hits are better than one: membrane-active and DNA binding-related double-action mechanism of NK-18, a novel antimicrobial peptide derived from mammalian NK-lysin.

The extensive use and misuse of antibiotics in medicine result in the emergence of multidrug-resistant bacteria, creating an urgent need for the development of new chemotherapeutic agents. Nowadays, antimicrobial peptides are widely recognized as a class of promising candidates with activity against multidrug-resistant bacteria. NK-18 is a truncated peptide derived from NK-Lysin, an effector of cytotoxic T cells and natural killer cells. In this study, we studied the antibacterial mechanism of action of NK-18. The results revealed that NK-18 has potent antibacterial activity against Escherichia coli and Staphylococcus aureus. According to our findings, NK-18 is membrane active and its target of action is not only the bacterial membrane but also the DNA in the cytoplasm. The double targets of NK-18 make it difficult for bacteria to generate resistance, which may present a new strategy to defend against multidrug-resistant bacteria and provide a new lead in the design of potent antimicrobial peptides with therapeutic application in the presence of increasing resistance to conventional antibiotics.

Membrane perturbation action mode and structure-activity relationships of Protonectin, a novel antimicrobial peptide from the venom of the neotropical social wasp Agelaia pallipes pallipes.

With the extensive use of antibiotics, multidrug-resistant bacteria emerge frequently. New antimicrobial agents with novel modes of action are urgently needed. It is now widely accepted that antimicrobial peptides (AMPs) could be promising alternatives to conventional antibiotics. In this study, we aimed to study the antimicrobial activity and mechanism of action of protonectin, a cationic peptide from the venom of the neotropical social wasp Agelaia pallipes pallipes. We demonstrated that protonectin exhibits potent antimicrobial activity against a spectrum of bacteria, including multidrug-resistant strains. To further understand this mechanism, the structural features of protonectin and its analogs were studied by circular dichroism (CD). The CD spectra demonstrated that protonectin and its natural analog polybia-CP formed a typical α-helical conformation in the membrane-mimicking environment, while its proline-substituted analog had much lower or even no α-helix conformation. Molecular dynamics simulations indicated that the α-helical conformation in the membrane is required for the exhibition of antibacterial activity. In conclusion, protonectin exhibits potent antimicrobial activity by disruption of the integrity of the bacterial membrane, and its α-helical confirmation in the membrane is essential for this action.

Adaptive Hierarchical Similarity Metric Learning With Noisy Labels.

Deep Metric Learning (DML) plays a critical role in various machine learning tasks. However, most existing deep metric learning methods with binary similarity are sensitive to noisy labels, which are widely present in real-world data. Since these noisy labels often cause a severe performance degradation, it is crucial to enhance the robustness and generalization ability of DML. In this paper, we propose an Adaptive Hierarchical Similarity Metric Learning method. It considers two noise-insensitive information, i.e., class-wise divergence and sample-wise consistency. Specifically, class-wise divergence can effectively excavate richer similarity information beyond binary in modeling by taking advantage of Hyperbolic metric learning, while sample-wise consistency can further improve the generalization ability of the model using contrastive augmentation. More importantly, we design an adaptive strategy to integrate this information in a unified view. It is noteworthy that the new method can be extended to any pair-based metric loss. Extensive experimental results on benchmark datasets demonstrate that our method achieves state-of-the-art performance compared with current deep metric learning approaches.

Membrane-active action mode of polybia-CP, a novel antimicrobial peptide isolated from the venom of Polybia paulista.

The extensive use of antibiotics in medicine, the food industry, and agriculture has resulted in the frequent emergence of multidrug-resistant bacteria, which creates an urgent need for new antibiotics. It is now widely recognized that antimicrobial peptides (AMPs) could play a promising role in fighting multidrug-resistant bacteria. Antimicrobial peptide polybia-CP was purified from the venom of the social wasp Polybia paulista. In this study, we synthesized polybia-CP and studied its action mode of antibacterial activity. Our results revealed that polybia-CP has potent antibacterial activity against both Gram-positive and Gram-negative bacteria. The results from both the real bacterial membrane and the in vitro model membrane showed that polybia-CP is membrane active and that its action target is the membrane of bacteria. It is difficult for bacteria to develop resistance to polybia-CP, which may thus offer a new strategy for defending against resistant bacteria in medicine and the food and farming industries.

One-pot enantioselective synthesis of functionalized pyranocoumarins and 2-amino-4H-chromenes: discovery of a type of potent antibacterial agent.

Function-oriented design and synthesis of chiral small molecules with novel activity is a key goal in modern organic chemistry. As multiple antibiotic-resistant pathogens are emerging and causing serious diseases, the need for practical routes for the development of new types of antibacterial agents is very urgent. Herein, we present a highly efficient process for the synthesis of optically active pyranocoumarins and 2-amino-4H-chromenes through an organocatalytic Knoevenagel/Michael/cyclization sequence, and the preliminary biological studies of these new heterocyclic compounds revealed potent antibacterial activity. This study provides a novel strategy for further research and development of new types of antibacterial agents effective against human pathogens.

The Antimicrobial Peptide Melectin Shows Both Antimicrobial and Antitumor Activity via Membrane Interference and DNA Binding.

PURPOSE: Increasingly complex diseases require novel drugs for their treatment. Antimicrobial peptides (AMPs) are promising candidate treatments due to their broad existence and special characteristics. However, the current understanding of AMPs is not sufficient to allow them to be produced commercially for clinical use. MATERIALS AND METHODS: Melectin, from the venom of the cleptoparasitic bee Melecta albifrons, does not exhibit sequence homology with other wasp venom peptides. To investigate this more deeply, we explored the antibacterial and antitumor activities of Melectin and related mechanisms. RESULTS: Our results demonstrate that Melectin possesses antimicrobial properties against standard sensitive/clinical drug-resistant bacteria strains as well as antitumor activity. It has an α-helix form and exhibits moderate cytotoxicity. Its action mechanisms are involved with membrane interfering and DNA binding. The membrane interfering effect was distinct between different phospholipid compositions. CONCLUSION: We found that Melectin may serve as a new potential template in the battle against multidrug resistance, and our study indicated that there are promising prospects for medically applicable drugs based on AMPs.

Identifying Imaging Markers for Predicting Cognitive Assessments Using Wasserstein Distances Based Matrix Regression.

Alzheimer's disease (AD) is a severe type of neurodegeneration which worsens human memory, thinking and cognition along a temporal continuum. How to identify the informative phenotypic neuroimaging markers and accurately predict cognitive assessment are crucial for early detection and diagnosis Alzheimer's disease. Regression models are widely used to predict the relationship between imaging biomarkers and cognitive assessment, and identify discriminative neuroimaging markers. Most existing methods use different matrix norms as the similarity measures of the empirical loss or regularization to improve the prediction performance, but ignore the inherent geometry of the cognitive data. To tackle this issue, in this paper we propose a novel robust matrix regression model with imposing Wasserstein distances on both loss function and regularization. It successfully integrate Wasserstein distance into the regression model, which can excavate the latent geometry of cognitive data. We introduce an efficient algorithm to solve the proposed new model with convergence analysis. Empirical results on cognitive data of the ADNI cohort demonstrate the great effectiveness of the proposed method for clinical cognitive predication.

Potent antitumor effects of a novel actinomycin D analog Leu5AMD.

Leu5AMD ([D-Val2, L-MeLeu5]2 AMD) is a novel actinomycin D (AMD) analog, in which both N-methylvalines were replaced by N-methylleucines. In the present study, an attempt has been made to investigate the effects of Leu5AMD on the proliferation of human gastric carcinoma cell line SGC-7901. The results showed that Leu5AMD inhibited the proliferation and induces apoptosis in SGC-7901 cells in a dose-dependent manner. Apoptosis induced by Leu5AMD was further confirmed by annexin V-FITC/PI dual staining assay. After treatment with Leu5AMD, the loss of mitochondrial potential and the decrease of bcl-2 gene expression were observed in apoptotic cells, suggesting that Leu5AMD may be involved in mitochondria and bcl-2 related apoptotic pathway. In addition, the in vivo antitumor effects of Leu5AMD on S-180 bearing mice and the acute toxicity on healthy mice were investigated. Treatment with Leu5AMD markedly suppressed the growth of Sarcoma xenograft. These results suggest that Leu5AMD may be used as a promising chemotherapeutical agent for patients affected by gastric carcinoma and other solid cancer.

Antitumor effects, cell selectivity and structure-activity relationship of a novel antimicrobial peptide polybia-MPI.

A novel antimicrobial peptide, polybia-MPI, was purified from the venom of the social wasp Polybia paulista. It has potent antimicrobial activity against both Gram-positive and Gram-negative bacteria, but causing no hemolysis to rat erythrocytes. To date, there is no report about its antitumor effects on any tumor cell lines. In this study we synthesized polybia-MPI and studied its antitumor efficacy and cell selectivity. Our results revealed that polybia-MPI exerts cytotoxic and antiproliferative efficacy by pore formation. It can selectively inhibit the proliferation of prostate and bladder cancer cells, but has lower cytotoxicity to normal murine fibroblasts. In addition, to investigate the structure-activity relationship of polybia-MPI, three analogs in which Leu7, Ala8 or Asp9 replaced by L-Pro were designed and synthesized. L-Pro substitution of Leu7 or Asp9 significantly reduces the content of alpha-helix conformation, and L-Pro substitution of Ala8 can disrupt the alpha-helix conformation thoroughly. The L-Pro substitution induces a significant reduction of antitumor activity, indicating that the alpha-helix conformation of polybia-MPI is important for its antitumor activity. In summary, polybia-MPI may offer a novel therapeutic strategy in the treatment of prostate cancer and bladder cancer, considering its relatively lower cytotoxicity to normal cells.

Arminin 1a-C, a novel antimicrobial peptide from ancient metazoan Hydra, shows potent antileukemia activity against drug-sensitive and drug-resistant leukemia cells.

PURPOSE: Due to the emergence of multidrug resistance (MDR), traditional antileukemia drugs no longer meet the treatment needs. Therefore, new antileukemia drugs with different action mechanisms are urgently needed to cope with this situation. MATERIALS AND METHODS: Arminin 1a-C is an antimicrobial peptide (AMP) developed from the ancient metazoan marine Hydra. In this study, we first explored its antileukemia activity. RESULTS: Our results showed that Arminin 1a-C formed an α-helical structure and efficaciously suppressed the viability of leukemia cell lines whether or not they were multidrug resistant or sensitive, and there were no obvious differences between these cell lines. Arminin 1a-C exhibited distinct selectivity between noncancerous and cancerous cell lines. Arminin 1a-C interfered with K562/adriamycin (ADM) cell (a kind of multidrug-resistant leukemia cell line) proliferation in a very rapid manner and formed pores in its cell membrane, making it difficult to develop resistance against Arminin 1a-C. CONCLUSION: Our data show that Arminin 1a-C possesses great potential as a therapeutic candidate for the treatment of multidrug-resistant leukemia.

Influence of Proline Substitution on the Bioactivity of Mammalian-Derived Antimicrobial Peptide NK-2.

Multidrug-resistant bacteria are emerging as a global threat, making the search for alternative compounds urgent. Antimicrobial peptides (AMPs) became a promising hotspot due to their distinct action mechanism and possibility to be used as an alternative or complement to traditional antibiotics. However, gaining a better understanding about the relationship between antimicrobial peptides structure and its bioactivity is crucial for the development of next generation of antimicrobial agents. NK-2, derived from mammalian protein NK-lysin, has potent antitumor and bactericidal abilities. As proline was considered to be an effective α-helix breaker due to its restricted conformation, to better comprehend the effects of proline in the structure-activity relationship of NK-2, we constructed two NK-2 analogs. We examined the biological activities of NK-2 and its proline substitution analogs and analyzed the resulting conformational changes. Our results showed that introducing proline into the primary sequence of NK-2 significantly decreased the antitumor, antibacterial, and cytotoxic effects, as well as DNA binding activity by changing the α-helix content. However, α-helical content was not the only determining factor, the position of proline inserted was also critical. This study will allow for clearer insight into the role of proline in structure and bioactivity of NK-2 and provide a foundation for future studies.

NK-18, a promising antimicrobial peptide: anti-multidrug resistant leukemia cells and LPS neutralizing properties.

With the increase of multidrug resistance, novel anti-leukemia agents with diverse mechanisms of action are required to address this challenge. NK-18, the core region of mammalian derived protein NK-lysin, effectively inhibited the viability of both multidrug resistant and sensitive leukemia cell lines. Meanwhile, this proliferation inhibition effect was not distinct between sensitive and multidrug resistant leukemia cell line. NK-18 showed selectivity between non-tumorigenic and tumorigenic cells. It preferentially bound to tumor cells whose outer leaflet with high phosphatidylserine content. NK-18 acted on the multidrug resistant leukemia cell line by a rapid pore formation on the cell membrane, it is not easy for K562/ADM cells developing resistance against NK-18. Furthermore, NK-18 could neutralize lipopolysaccharides by electrostatic attraction and reduce NO production. These research data demonstrated NK-18 possesses great advantage in the multidrug resistant leukemia treatment compared with conventional chemotherapies and it could be a potential candidate for further research.

Dual antifungal properties of cationic antimicrobial peptides polybia-MPI: membrane integrity disruption and inhibition of biofilm formation.

With the increasing emergence of resistant fungi, the discovery and development of novel antifungal therapeutics were urgently needed. Compared with conventional antibiotics, the limited propensity of AMPs to induce resistance in pathogens has attracted great interest. In the present study, the antifungal activity and its mechanism-of-action of polybia-MPI, a cationic peptide from the venom of Social wasp Polybia Paulista was investigated. We demonstrated that polybia-MPI could potently inhibit the growth of Candida albicans (C. albicans) and Candida glabrata (C. glabrata). The 50% inhibitory concentrations (IC50) of Polybia-MPI against cancer cells were much higher than the MICs against the tested C. albicans and C. glabrata cells, indicating that polybia-MPI had high selectivity between the fungal and mammalian cells. Our results also indicated that membrane disturbance mechanism was involved in the antifungal activity. Furthermore, polybia-MPI could inhibit the bio film forming of C. glabrata, which was frequently associated with clinically significant biofilm. These results suggest that polybia-MPI has great advantages in the development of antifungal agents.

Membrane active antimicrobial activity and molecular dynamics study of a novel cationic antimicrobial peptide polybia-MPI, from the venom of Polybia paulista.

As the frequent emergence of the resistant bacteria, the development of new agents with a new action mode attracts a great deal of interest. It is now widely accepted that antimicrobial peptides (AMPs) are promising alternatives to conventional antibiotics. In this study, antimicrobial peptide polybia-MPI and its analogs were synthesized and their antibacterial activity was studied. Our results revealed that polybia-MPI has potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Its ability to make PI permeate into bacteria and lead to the leakage of calcein from model membrane LUVs, suggests a killing mechanism involving membrane perturbation. SEM and TEM microscopy experiments verified that the morphology of bacteria was changed greatly under the treatment of polybia-MPI. Compared with the conventional chemotherapy, polybia-MPI targets the cell membrane rather than entering into the cell to exert its antibacterial activity. Furthermore, molecular dynamics (MD) simulations were employed to investigate the mechanism of membrane perturbation. The results indicated that the α-helical conformation in the membrane is required for the exhibition of antibacterial activity and the membrane disturbance by polybia-MPI is a cooperative process. In conclusion, with the increasing resistance to conventional antibiotics, there is no doubt that polybia-MPI could offer a new strategy to defend the resistant bacteria.