Neuroprotective amyloid ß N-terminal peptides differentially alter human α7- and α7ß2-nicotinic acetylcholine (nACh) receptor single-channel properties.

BACKGROUND AND PURPOSE: Oligomeric amyloid ß 1-42 (oAß1-42) exhibits agonist-like action at human α7- and α7ß2-containing nicotinic receptors. The N-terminal amyloid ß1-15 fragment (N-Aß fragment) modulates presynaptic calcium and enhances hippocampal-based synaptic plasticity via α7-containing nicotinic receptors. Further, the N-Aß fragment and its core sequence, the N-amyloid-beta core hexapeptide (N-Aßcore), protect against oAß1-42-associated synapto- and neurotoxicity. Here, we investigated how oAß1-42, the N-Aß fragment, and the N-Aßcore regulate the single-channel properties of α7- and α7ß2-nicotinic receptors. EXPERIMENTAL APPROACH: Single-channel recordings measured the impact of acetylcholine, oAß1-42, the N-Aß fragment, and the N-Aßcore on the unitary properties of human α7- and α7ß2-containing nicotinic receptors expressed in nicotinic-null SH-EP1 cells. Molecular dynamics simulations identified potential sites of interaction between the N-Aß fragment and orthosteric α7+/α7- and α7+/ß2- nicotinic receptor binding interfaces. KEY RESULTS: The N-Aß fragment and N-Aßcore induced α7- and α7ß2-nicotinic receptor single-channel openings. Relative to acetylcholine, oAß1-42 preferentially enhanced α7ß2-nicotinic receptor single-channel open probability and open-dwell times. Co-application with the N-Aßcore neutralized these effects. Further, administration of the N-Aß fragment alone, or in combination with acetylcholine or oAß1-42, selectively enhanced α7-nicotinic receptor open probability and open-dwell times (compared to acetylcholine or oAß1-42). CONCLUSIONS AND IMPLICATIONS: Amyloid-beta peptides demonstrate functional diversity in regulating α7- and α7ß2-nicotinic receptor function, with implications for a wide range of nicotinic receptor-mediated functions in Alzheimer's disease. The effects of these peptides on α7- and/or α7ß2-nicotinic receptors revealed complex interactions with these subtypes, providing novel insights into the neuroprotective actions of amyloid ß-derived fragments against the toxic effects of oAß1-42.

Sequence-dependent effects of hematoporphyrin derivatives (HPD) photodynamic therapy and cisplatin on lung adenocarcinoma cells.

BACKGROUND: Hematoporphyrin derivatives (HPD)-Photodynamic therapy (PDT) in combination with cisplatin (DDP) is an effective anticancer strategy. However, whether the order of combination affects efficacy has not been studied. METHODS: The human lung adenocarcinoma (LUAD) A549 cells were used as the study subjects. After A549 cells were treated with a single medication (PDT/DDP) or a sequential combination (PDT + DDP / DDP + PDT), the cell viability was assayed using the cell counting kit-8 method. Hoechst staining, Annexin-V/propidium iodide (PI) double staining, western blotting, and a real-time quantitative polymerase chain reaction (RT-qPCR) were performed to examine the mechanisms behind the combined effects. RESULTS: A synergistic impact between HPD-PDT and DDP was found. The cell viability in the PDT+DDP group was significantly lower than in the DDP+PDT group. A significant apoptotic profile and a high apoptotic rate were seen in the PDT + DDP group. The western blot showed that the expression levels of Bcl2-associated x(Bax) and cleaved-poly ADP-ribose polymerase (PARP) increased, and those of B-cell lymphoma-2 (Bcl-2) and Caspase-9 decreased in the PDT + DDP group. At the same time, the RT-qPCR revealed the upregulation of Bax and PARP mRNA and the downregulation of Bcl-2 and Caspase-9 mRNA. CONCLUSION: The order of the combination therapy (PDT + DDP / DDP + PDT) was important. The HPD-PDT followed by DDP significantly inhibited LUAD cell viability, which may be related to the mitochondrial apoptotic pathway.

Analogs of α-conotoxin PnIC selectively inhibit α7ß2- over α7-only subtype nicotinic acetylcholine receptors via a novel allosteric mechanism.

This study was undertaken to identify and characterize the first ligands capable of selectively identifying nicotinic acetylcholine receptors containing α7 and ß2 subunits (α7ß2-nAChR subtype). Basal forebrain cholinergic neurons express α7ß2-nAChR. Here, they appear to mediate neuronal dysfunction induced by the elevated levels of oligomeric amyloid-ß associated with early Alzheimer's disease. Additional work indicates that α7ß2-nAChR are expressed across several further critically important cholinergic and GABAergic neuronal circuits within the central nervous system. Further studies, however, are significantly hindered by the inability of currently available ligands to distinguish heteromeric α7ß2-nAChR from the closely related and more widespread homomeric α7-only-nAChR subtype. Functional screening using two-electrode voltage-clamp electrophysiology identified a family of α7ß2-nAChR-selective analogs of α-conotoxin PnIC (α-CtxPnIC). A combined electrophysiology, functional kinetics, site-directed mutagenesis, and molecular dynamics approach was used to further characterize the α7ß2-nAChR selectivity and site of action of these α-CtxPnIC analogs. We determined that α7ß2-nAChR selectivity of α-CtxPnIC analogs arises from interactions at a site distinct from the orthosteric agonist-binding site shared between α7ß2- and α7-only-nAChR. As numerous previously identified α-Ctx ligands are competitive antagonists of orthosteric agonist-binding sites, this study profoundly expands the scope of use of α-Ctx ligands (which have already provided important nAChR research and translational breakthroughs). More immediately, analogs of α-CtxPnIC promise to enable, for the first time, both comprehensive mapping of the distribution of α7ß2-nAChR and detailed investigations of their physiological roles.

Recurrent Ventricular Fibrillation in an Apparently Healthy Patient.

This case report describes a patient in their 50s who collapsed, received chest compressions, and recovered consciousness at home.

Effect of a 630 nm light on vasculogenic mimicry in A549 lung adenocarcinoma cells in vitro.

OBJECTIVE: The objective of this study was to investigate the effect of photodynamic therapy (PDT) on the formation of vasculogenic mimicry (VM) in the human lung adenocarcinoma A549 cell line in vitro. METHODS: The participants were divided into a blank control group, a photosensitizer group, a light group, and a PDT group. Cells from each group were cultured in three dimensions using Matrigel, and vasculogenic mimicry generation was observed microscopically. Periodic Acid-Schiff (PAS) staining was used to verify the vasculogenic mimicry structure. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was used to detect the expression levels of cellular osteopontin (OPN) and vascular endothelial growth factor (VEGF) mRNA. Western blotting was used to detect the expression levels of cellular OPN and VEGF protein. RESULTS: A549 cells cultured on Matrigel for about six hours revealed VM on PAS staining, and the number of formations was significantly reduced in the PDT group compared with other groups (P < 0.05). The RT-PCR results showed that the PDT group downregulated OPN and VEGF mRNA expression compared with each control group (P < 0.05). Western blot results showed that OPN and VEGF protein expression was downregulated in the PDT group compared with each control group (P < 0.05). The results of RT-PCR showed that the expression of OPN and VEGF mRNA was downregulated in the PDT group compared with each control group (P < 0.05). The results of Western blotting showed that the expression of OPN and VEGF was downregulated in the protein PDT group compared with each control group (P < 0.001). CONCLUSION: Photodynamic therapy significantly inhibited the formation of vasculogenic mimicry in human lung adenocarcinoma A549 cells in vitro and downregulated the expression of OPN, VEGF mRNA, and protein levels.

A rare case of pulmonary artery embolism with choriocarcinoma: A case report and literature review.

Pulmonary embolism (PE) caused by malignant tumor is not uncommon, but pulmonary artery with choriocarcinoma is rare and difficult to timely diagnose and effectively treat. To the best of our knowledge, there are only 15 cases reported at present in the literature that present variable clinical characteristics and prognosis. In the current study reports a 21-year-old female with a history of chest pain and slight fever for 4 months who was treated as a case of pneumonia. Owing to the recurrence of the symptoms, a contrast-enhanced chest computer tomography scan was performed on the patient, which revealed complete occlusion of the right pulmonary artery. The patient was diagnosed to have pulmonary embolism (PE). However, no abnormalities were observed in D-dimer value, tumor antigen testing or ultrasonography. Positron emission tomography/computed tomography (PET/CT) was performed, which revealed the abnormal hypermetabolic lesion of the right pulmonary artery. Following the laboratory report of a significantly elevated human chorionic gonadotropin ß-subunit level combined with characteristic appearance of PET-CT, the diagnosis of primary pulmonary artery with choriocarcinoma was established based on guidelines of the European Society for Medical Oncology and the criteria formulated by the International Federation of Gynecology and Obstetrics. The patient underwent chemotherapy and responded well to the treatment. Although rare, choriocarcinoma should be considered for any fertile women who presents with a massive PE. These findings emphasize the importance of the early diagnosis and treatment of this disease.

Body composition and dietary intake in patients with head and neck cancer during radiotherapy: a longitudinal study.

OBJECTIVES: To investigate the body composition and dietary intake in the patients with head and neck cancer (HNC) during radiotherapy (RT), and explore the relationship between them. METHODS: This was a prospective, longitudinal observational study. Adult patients with HNC undergoing RT between March 2017 and August 2018 were recruited. Patients' body compositions were evaluated by bioelectrical impedance analysis, and dietary intake was recorded by 24-hour dietary recall at three time points, including baseline (T1), mid-treatment (T2) and post-treatment (T3). Patients were divided into low, middle and high energy intake groups based on the average daily energy intake (DEI). Changes in body weight (BW), fat mass (FM), fat-free mass (FFM) and skeletal muscle mass (SMM) among these three groups were compared. RESULTS: From T1 to T3, the median loss of patients' BW, FM, FFM and SMM was 4.60, 1.90, 2.60 and 1.50 kg, respectively. The loss of BW was more dramatic from T2 to T3 than that from T1 to T2. BW loss was mainly contributed by SMM loss from T1 to T2 and by FM loss from T2 to T3. Meanwhile, patients' dietary intake reduced during treatment. High DEI group had a significantly attenuated loss of patients' BW, FFM, SMM and FM compared with the low DEI group. CONCLUSION: Patients' BW, FM, FFM and SMM all significantly reduced, especially from T2 to T3, with decreased DEI during RT, which stresses the importance of nutrition intervention during the whole course of RT.

Binding of human ACE2 and RBD of Omicron enhanced by unique interaction patterns among SARS-CoV-2 variants of concern.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing COVID-19, has continued to mutate and spread worldwide despite global vaccination efforts. In particular, the Omicron variant, first identified in South Africa in late November 2021, has become the dominant strain worldwide. Compared to the original strain identified in Wuhan, Omicron features 50 genetic mutations, with 15 mutations in the receptor-binding domain (RBD) of the spike protein, which binds to the human angiotensin-converting enzyme 2 (ACE2) receptor for viral entry. However, it is not completely understood how these mutations alter the interaction and binding strength between the Omicron RBD and ACE2. In this study, we used a combined steered molecular dynamics (SMD) simulation and experimental microscale thermophoresis (MST) approach to quantify the interaction between Omicron RBD and ACE2. We report that the Omicron brings an enhanced RBD-ACE2 interface through N501Y, Q498R, and T478K mutations; the changes further lead to unique interaction patterns, reminiscing the features of previously dominated variants, Alpha (N501Y) and Delta (L452R and T478K). Among the Q493K and Q493R, we report that Q493R shows stronger binding to ACE2 than Q493K due to increased interactions. Our MST data confirmed that the Omicron mutations in RBD are associated with a five-fold higher binding affinity to ACE2 compared to the RBD of the original strain. In conclusion, our results could help explain the Omicron variant's prevalence in human populations, as higher interaction forces or affinity for ACE2 likely promote greater viral binding and internalization, leading to increased infectivity.

Identification of novel B-1 transitional progenitors by B-1 lymphocyte fate-mapping transgenic mouse model Bhlhe41 dTomato-Cre.

B-1 lymphocytes exhibit specialized roles in host defense against multiple pathogens. Despite the fact that CD19+CD93+B220lo/- B cells have been identified as B-1 progenitors, the definition for B-1 progenitors remains to be elucidated as CD19+CD93+B220+ B cells are capable to give rise to B-1 cells. Given that transcription factor Bhlhe41 is highly and preferentially expressed in B-1 cells and regulates B-1a cell development, we generated a transgenic mouse model, Bhlhe41dTomato-Cre , for fate mapping and functional analysis of B-1 cells. Bhlhe41dTomato-Cre mice efficiently traced Bhlhe41 expression, which was mainly restricted to B-1 cells in B-cell lineage. We showed an efficient and specific Cre-mediated DNA recombination in adult B-1 cells and neonatal B-1 progenitors rather than B-2 cells by flow cytometric analysis of Bhlhe41 dTomato-Cre/+ Rosa26 EYFP mice. Treatment of Bhlhe41 dTomato-Cre/+ Rosa26 iDTR mice with diphtheria toxin revealed a robust efficacy of B-1 cell depletion. Interestingly, using Bhlhe41 dTomato-Cre mice, we demonstrated that neonatal B-1 progenitors (CD19+CD93+B220lo/-) expressed Bhlhe41 and were identical to well-defined transitional B-1a progenitors (CD19+CD93+B220lo/-CD5+), which only gave rise to peritoneal B-1a cells. Moreover, we identified a novel population of neonatal splenic CD19hidTomato+B220hiCD43loCD5lo B cells, which differentiated to peritoneal B-1a and B-1b cells. Bhlhe41 deficiency impaired the balance between CD19hidTomato+B220lo/-CD5hi and CD19hidTomato+B220hiCD5lo cells. Hence, we identified neonatal CD19hidTomato+B220hiCD43loCD5lo B cells as novel transitional B-1 progenitors. Bhlhe41 dTomato-Cre/+ mouse can be used for fate mapping and functional studies of B-1 cells in host-immune responses.

OsRAD51 Plays a Vital Role in Promoting Homologous Recombination in Rice Meiosis.

Meiotic recombination plays a pivotal role in achieving accurate chromosomal segregation and increasing genetic diversity. In the homologous recombination pathway, the detailed mechanisms of how OsRAD51 and OsDMC1 work in rice meiosis remain to be explored. Here, we obtained different types of mutants for Osrad51a1, Osrad51a2, Osdmc1a, and Osdmc1b through CRISPR/Cas9. Both Osrad51a1 and Osrad51a2 exhibited normal vegetative growth and fertility. Osrad51 (Osrad51a1 Osrad51a2) mutant plants show normal vegetative growth but exhibit complete sterility, indicating that OsRAD51A1 and OsRAD51A2 are functionally redundant in rice fertility. In contrast to the wild type, Osrad51 chromosomes are not paired perfectly at pachytene and synaptonemal complex (SC) formation is deficient. Moreover, univalents and multivalent associations were observed at metaphase I, chromosome fragments presented at anaphase I, and crossover formation is basically suppressed in Osrad51 pollen mother cells (PMCs). OsRAD51 foci emerge at leptotene and disappear from late pachytene and chromosome localization of OsRAD51 depends on the formation of double-strand breaks (DSBs). Most OsRAD51 foci can co-localize with OsDMC1 signals. OsRAD51 is essential for the loading of OsDMC1 onto chromosomes, and vice versa. In addition, both OsRAD51 and OsDMC1 can interact with OsFIGL1 and OsBRCA2, two important components in rice meiosis. Moreover, the Osrad51 Osdmc1 (Osrad51a1 Osrad51a2 Osdmc1a Osdmc1b) quadruple mutant PMCs exhibited similar defective phenotypes as Osrad51 in homologous pairing, synapsis, and DSB repair. Taken together, our results suggest that the recombinases DMC1 and RAD51 may functionally depend on each other and play important roles in meiotic recombination during meiosis in rice.

FIGNL1 Inhibits Non-homologous Chromosome Association and Crossover Formation.

Meiotic crossovers (COs) not only generate genetic diversity but also ensure the accuracy of homologous chromosome segregation. Here, we identified FIGNL1 as a new inhibitor for extra crossover formation in rice. The fignl1 mutant displays abnormal interactions between non-homologous chromosomes at diakinesis, and chromosome bridges and fragmentation at subsequent stages of meiosis, but shows normal homologous chromosome pairing and synapsis during early prophase I. FIGNL1 participates in homologous chromosome recombination and functions downstream of DMC1. Mutation of FIGNL1 increases the number of bivalents in zip4 mutants, but does not change the number of HEI10 foci, indicating that FIGNL1 functions in limiting class II CO formation. FIGNL1 interacts with MEICA1, and colocalizes with MEICA1 in a dynamic pattern as punctate foci located between two linear homologous chromosomes. The localization of FIGNL1 depends on ZEP1-mediated assembly of the synaptonemal complex. Based on these results, we propose that FIGNL1 inhibits non-homologous chromosome interaction and CO formation during rice meiosis.

Machine learning predicts cancer-associated deep vein thrombosis using clinically available variables.

PURPOSE: To develop and validate machine learning (ML) models for cancer-associated deep vein thrombosis (DVT) and to compare the performance of these models with the Khorana score (KS). METHODS: We randomly extracted data of 2100 patients with cancer between Jan. 1, 2017, and Oct. 31, 2019, and 1035 patients who underwent Doppler ultrasonography were enrolled. Univariate analysis and Lasso regression were applied to select important predictors. Model training and hyperparameter tuning were implemented on 70% of the data using a ten-fold cross-validation method. The remaining 30% of the data were used to compare the performance with seven indicators (area under the receiver operating characteristic curve [AUC], sensitivity, specificity, accuracy, balanced accuracy, Brier score, and calibration curve), among all five ML models (linear discriminant analysis [LDA], logistic regression [LR], classification tree [CT], random forest [RF], and support vector machine [SVM]), and the KS. RESULTS: The incidence of cancer-associated DVT was 22.3%. The top five predictors were D-dimer level, age, Charlson Comorbidity Index (CCI), length of stay (LOS), and previous VTE (venous thromboembolism) history according to RF. Only LDA (AUC = 0.773) and LR (AUC = 0.772) outperformed KS (AUC = 0.642), and combination with D-dimer showed improved performance in all models. A nomogram and web calculator https://webcalculatorofcancerassociateddvt.shinyapps.io/dynnomapp/ were used to visualize the best recommended LR model. CONCLUSION: This study developed and validated cancer-associated DVT predictive models using five ML algorithms and visualized the best recommended model using a nomogram and web calculator. The nomogram and web calculator developed in this study may assist doctors and nurses in evaluating individualized cancer-associated DVT risk and making decisions. However, other prospective cohort studies should be conducted to externally validate the recommended model.

Binding of Human ACE2 and RBD of Omicron Enhanced by Unique Interaction Patterns Among SARS-CoV-2 Variants of Concern.

The 2019 coronavirus disease (COVID-19) pandemic has had devastating impacts on our global health. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing COVID-19, has continued to mutate and spread worldwide despite global vaccination efforts. In particular, the Omicron variant, first identified in South Africa in late November 2021, has now overtaken the Delta variant and become the dominant strain worldwide. Compared to the original strain identified in Wuhan, Omicron features 50 genetic mutations, with 15 mutations in the receptor-binding domain (RBD) of the spike protein, which binds to the human angiotensin-converting enzyme 2 (ACE2) receptor for viral entry. However, it is not completely understood how these mutations alter the interaction and binding strength between the Omicron RBD and ACE2. In this study, we used a combined steered molecular dynamics (SMD) simulation and experimental microscale thermophoresis (MST) approach to quantify the interaction between Omicron RBD and ACE2. We report that the Omicron brings an enhanced RBD-ACE2 interface through N501Y, Q493K/R, and T478K mutations; the changes further lead to unique interaction patterns, reminiscing the features of previously dominated variants, Alpha (N501Y) and Delta (L452R and T478K). Our MST data confirmed that the Omicron mutations in RBD are associated with a five-fold higher binding affinity to ACE2 compared to the RBD of the original strain. In conclusion, our result could help explain the Omicron variant’s prevalence in human populations, as higher interaction forces or affinity for ACE2 likely promote greater viral binding and internalization, leading to increased infectivity.

Nitrogen nutrition contributes to plant fertility by affecting meiosis initiation.

Nitrogen (N), one of the most important plant nutrients, plays crucial roles in multiple plant developmental processes. Spikelets are the primary sink tissues during reproductive growth, and N deficiency can cause floral abortion. However, the roles of N nutrition in meiosis, the crucial step in plant sexual reproduction, are poorly understood. Here, we identified an N-dependent meiotic entrance mutant with loss of function of ELECTRON TRANSFER FLAVOPROTEIN SUBUNIT ß (ETFß) in rice (Oryza sativa). etfß displayed meiosis initiation defects, excessive accumulation of branched-chain amino acids (BCAAs) and decrease in total N contents in spikelets under N starvation, which were rescued by applying excess exogenous inorganic N. Under N starvation, ETFß, through its involvement in BCAA catabolism, promotes N reutilization and contributes to meeting N demands of spikelets, highlighting the impact of N nutrition on meiosis initiation. We conclude that N nutrition contributes to plant fertility by affecting meiosis initiation.

An efficient and cost-effective method for the purification of human basophils.

Human basophils are terminally differentiated granulocytes that are least abundant in the peripheral blood but play important roles in allergic diseases. Studies on human basophils are limited by the high cost on the isolation of human basophils by magnetic-activated cell sorting (MACS) for negative depletion of non-basophils, followed by CD123-based positive selection of basophils. Moreover, such CD123-based purification of basophils may be limited by blocking of the binding of IL-3/anti-CD123 to the surface CD123. Here we identified SSClow CD4- CD127- HLA-DR- CRTH2high as unique markers for the identification of human basophils through stringent flow cytometric analysis of leukocytes from buffy coat. We established an efficient and cost-effective method for isolating human basophils from buffy coat based on positive magnetic selection of CRTH2+ cells followed by flow cytometric sorting of SSClow CD4- CD127- HLA-DR- CRTH2high cells. Approximately 1 to 1.5 million basophils were isolated from one buffy coat with a purity of >97%. Basophils purified by this method were viable and efficiently responded to key regulators of basophils including IL-3 and anti-IgE. This method can be used for purifying human basophils for subsequent functional studies.