The significance of detecting HBV pgRNA and HBcrAg in HBV patients treated with NAs.

The value of detecting hepatitis B virus (HBV), pregenomic RNA (pgRNA), and hepatitis B core-related antigen (HBcrAg), both separately and jointly, in the management of HBV patients undergoing treatment with Nucleotide Analog was investigated. A total of 149 HBV patients who were being treated with Nucleotide Analog were enrolled in this study. The quantitative levels of HBV pgRNA and HBcrAg in the sera of these patients were determined, aiming to comprehend their replication levels and expression during the course of antiviral therapy. The patients were separated into 3 groups based on treatment duration: treatment time ≤ 12 months, treatment time ranging from 12 months to <60 months, and treatment time ≥ 60 months. Significantly different levels of HBcrAg and HBV pgRNA were observed among 3 groups (P < .05). In the group of patients with positive hepatitis B e antigen, both HBcrAg and pgRNA levels were higher compared to the group with negative hepatitis B e antigen, and this difference between the 2 groups was found to be statistically significant. Stratified analysis based on levels of hepatitis B surface antigen (HBsAg) revealed that the group with HBsAg levels < 100 IU/mL had lower levels of both HBcrAg and pgRNA compared to the group with HBsAg levels ≥ 100 IU/mL (P < .001). Following antiviral therapy, various degrees of transcription of covalently closed circular DNA continue to exist within the liver of HBV patients. The levels of serum HBcrAg and HBV pgRNA vary among patients with different treatment durations, indicating their efficacy in evaluating disease conditions during antiviral therapy.

PPP2R1A silencing suppresses LUAD progression by sensitizing cells to nelfinavir-induced apoptosis and pyroptosis.

Lung adenocarcinoma is a major public health problem with the low 5-year survival rate (15%) among cancers. Aberrant alterations of meiotic genes, which have gained increased attention recently, might contribute to elevated tumor risks. However, systematic and comprehensive studies based on the relationship between meiotic genes and LUAD recurrence and treatment response are still lacking. In this manuscript, we first confirmed that the meiosis related prognostic model (MRPM) was strongly related to LUAD progression via LASSO-Cox regression analyses. Furthermore, we identified the role of PPP2R1A in LUAD, which showed more contributions to LUAD process compared with other meiotic genes in our prognostic model. Additionally, repression of PPP2R1A enhances cellular susceptibility to nelfinavir-induced apoptosis and pyroptosis. Collectively, our findings indicated that meiosis-related genes might be therapeutic targets in LUAD and provided crucial guidelines for LUAD clinical intervention.

GINS2 regulates temozolomide chemosensitivity via the EGR1/ECT2 axis in gliomas.

Temozolomide (TMZ), a DNA alkylating agent, has become the primary treatment for glioma, the most common malignancy of the central nervous system. Although TMZ-containing regimens produce significant clinical response rates, some patients inevitably suffer from inferior treatment outcomes or disease relapse, likely because of poor chemosensitivity of glioma cells due to a robust DNA damage response (DDR). GINS2, a subunit of DNA helicase, contributes to maintaining genomic stability and is highly expressed in various cancers, promoting their development. Here, we report that GINS2 was upregulated in TMZ-treated glioma cells and co-localized with γH2AX, indicating its participation in TMZ-induced DDR. Furthermore, GINS2 regulated the malignant phenotype and TMZ sensitivity of glioma cells, mostly by promoting DNA damage repair by affecting the mRNA stability of early growth response factor 1 (EGR1), which in turn regulates the transcription of epithelial cell-transforming sequence 2 (ECT2). We constructed a GINS2-EGR1-ECT2 prognostic model, which accurately predicted patient survival. Further, we screened Palbociclib/BIX-02189 which dampens GINS2 expression and synergistically inhibits glioma cell proliferation with TMZ. These findings delineate a novel mechanism by which GINS2 regulates the TMZ sensitivity of glioma cells and propose a promising combination therapy to treat glioma.

BDH1-mediated LRRC31 regulation dependent on histone lysine ß-hydroxybutyrylation to promote lung adenocarcinoma progression.

Lung adenocarcinoma (LUAD) is the most common form of lung cancer, with a consistently low 5-year survival rate. Therefore, we aim to identify key genes involved in LUAD progression to pave the way for targeted therapies in the future. BDH1 plays a critical role in the conversion between acetoacetate and ß-hydroxybutyrate. The presence of ß-hydroxybutyrate is essential for initiating lysine ß-hydroxybutyrylation (Kbhb) modifications. Histone Kbhb at the H3K9 site is attributed to transcriptional activation. We unveiled that ß-hydroxybutyrate dehydrogenase 1 (BDH1) is not only conspicuously overexpressed in LUAD, but it also modulates the overall intracellular Kbhb modification levels. The RNA sequencing analysis revealed leucine-rich repeat-containing protein 31 (LRRC31) as a downstream target gene regulated by BDH1. Ecologically expressed BDH1 hinders the accumulation of H3K9bhb in the transcription start site of LRRC31, consequently repressing the transcriptional expression of LRRC31. Furthermore, we identified potential BDH1 inhibitors, namely pimozide and crizotinib, which exhibit a synergistic inhibitory effect on the proliferation of LUAD cells exhibiting high expression of BDH1. In summary, this study elucidates the molecular mechanism by which BDH1 mediates LUAD progression through the H3K9bhb/LRRC31 axis and proposes a therapeutic strategy targeting BDH1-high-expressing LUAD, providing a fresh perspective for LUAD treatment.

A Case of Pyoderma Gangrenosum after Partial Small Bowel Resection.

ABSTRACT: Pyoderma gangrenosum (PG) is a rare, noninfectious inflammatory disease of unknown etiology that affects the skin and mucous membranes. The development of PG after partial small bowel resection is very rare and can initially resemble an infectious complication, although it is an inflammatory disease.This report presents the case of a 55-year-old man who underwent partial small bowel resection for incomplete intestinal obstruction and developed postoperative infection-like manifestations, including redness and swelling of the incision, severe pain, and yellow-green turbid fluid from the drainage tube. After completing a skin biopsy that suggested massive neutrophil infiltration, multiple secretion cultures for Pseudomonas aeruginosa (+), and systemic screening without other comorbidities, a diagnosis of postoperative PG and P aeruginosa infection was determined.Early detection of this complication is essential for patient recovery because primary surgical treatment, which is contraindicated in such cases, can worsen PG. Therefore, PG should be treated conservatively with corticosteroids.

KIF20A is associated with clinical prognosis and synergistic effect of gemcitabine combined with ferroptosis inducer in lung adenocarcinoma.

Gemcitabine (GEM), an antimetabolite that terminates DNA synthesis, is commonly used in the treatment of cancers including lung adenocarcinoma (LUAD). However, downregulation of sensitivity limits the therapeutic effect. Ferroptosis as the new form of regulated cell death has been shown to have great potential for cancer treatment with chemoresistance. Here, three genes with both ferroptosis and GEM-response-associated features were screened from RNA sequencing and public data for constructing an independent risk model. LUAD patients with different risk scores had differences in mutational landscape, gene enrichment pathways, and drug sensitivity. By Cell Counting Kit-8 assay, flow cytometry, and colony forming assay, we demonstrate that GEM and ferroptosis inducer (FIN) imidazole Ketone Erastin had a synergistic combined anti-proliferative effect on LUAD cells and knockdown of KIF20A (the core gene of our model) further enhanced cell death in vitro by inducing ferroptosis. In conclusion, we identified a link between ferroptosis and GEM response in LUAD cells and developed a robust signature that can effectively classify LUAD patients into subgroups with different overall survival. For LUAD, the combined treatment modality of GEM and FIN is potentially effective and KIF20A may be a new therapeutic target.

NCAPG2 Maintains Cancer Stemness and Promotes Erlotinib Resistance in Lung Adenocarcinoma.

Erlotinib is a highly specific and reversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), but resistance inevitably develops as the disease progresses. Erlotinib resistance and cancer stem cells (CSCs) are poor factors hindering the prognosis of patients with lung adenocarcinoma (LUAD). Although studies have shown that erlotinib resistance and CSCs can jointly promote cancer development, the mechanism is currently unclear. Here, we investigated the potential biomarker and molecular mechanism of erlotinib resistance and cancer stemness in LUAD. An erlotinib resistance model based on four genes was constructed from The Cancer Genome Atlas (TCGA), the GEO database, the Cancer Cell Line Encyclopedia (CCLE), and the Genomics of Drug Sensitivity in Cancer (GDSC). Through multiple bioinformatic analyses, NCAPG2 was identified as a key gene for erlotinib resistance and stemness in LUAD. Further in vitro experiments demonstrated that NCAPG2 maintains stemness and contributes to erlotinib resistance in LUAD. In summary, NCAPG2 plays a vital role in stemness and erlotinib resistance in LUAD.

TIAM2 Contributes to Osimertinib Resistance, Cell Motility, and Tumor-Associated Macrophage M2-like Polarization in Lung Adenocarcinoma.

Background: Osimertinib-based therapy effectively improves the prognosis of lung adenocarcinoma (LUAD) patients with epidermal growth factor receptor mutations. However, patients will have cancer progression after approximately one year due to the occurrence of drug resistance. Extensive evidence has revealed that lipid metabolism and tumor-associated macrophage (TAM) are associated with drug resistance, which deserves further exploration. Methods: An osimertinib resistance index (ORi) was built to investigate the link between lipid metabolism and osimertinib resistance. The ORi was constructed and validated using TCGA and GEO data, and the relationship between ORi and immune infiltration was discussed. Weighted gene co-expression network analysis based on the M2/M1 macrophage ratio determined the hub gene TIAM2 and the biological function of TIAM2 in LUAD was verified in vitro. Results: ORi based on nine lipid metabolism-related genes was successfully constructed, which could accurately reflect the resistance of LUAD patients to osimertinib, predict the prognosis, and correlate with M2-like TAM. Additionally, TIAM2 was found to increase osimertinib tolerance, enhance cell motility, and promote M2-like TAM polarization in LUAD. Conclusions: The lipid metabolism gene is strongly connected with osimertinib resistance. TIAM2 contributes to osimertinib resistance, enhances cell motility, and induces M2-like TAM polarization in LUAD.

Effects of Flash Evaporation Conditions on the Quality of UHT Milk by Changing the Dissolved Oxygen Content in Milk.

This study assessed the impact of reducing dissolved oxygen (DO) content on the quality of UHT milk using a flash deoxygenation treatment. Flash deoxygenation was designed based on preheated milk reaching boiling early under low-pressure conditions to remove DO from the milk. Two parameters were designed for flash deoxygenation: preheating temperature 65 °C, -0.08 Mpa, and 70 °C, -0.06 Mpa. The flash conditions were applied to two UHT sterilization conditions (135 °C for 10 s and 145 °C for 5 s). After deoxygenation, the total oxidation (TOTOX) value of UHT milk was reduced by 1.4~1.71, and the protein carbonyl (PC) value was reduced by 1.15~1.52 nmol/mg of protein. The maximum inhibition rates of furusine and 5-HMF were 33.23 ± 1.72% and 25.43 ± 3.14%, respectively. The particle size was reduced by 0.141~0.178 µm. The ketones and stale aldehydes causing oxidized taste in the UHT milk were significantly reduced. This study showed that the oxidation and Maillard reactions of UHT milk were significantly inhibited, stability was improved, and the content of undesirable volatile flavor substances was reduced after flash deoxygenation. Therefore, reducing DO content was beneficial to improving the quality of UHT milk.

FMR1 is identified as an immune-related novel prognostic biomarker for renal clear cell carcinoma: A bioinformatics analysis of TAZ/YAP.

WW domain-containing transcription regulator 1 (TAZ, or WWTR1) and Yes-associated protein 1 (YAP) are both important effectors of the Hippo pathway and exhibit different functions. However, few studies have explored their co-regulatory mechanisms in kidney renal clear cell carcinoma (KIRC). Here, we used bioinformatics approaches to evaluate the co-regulatory roles of TAZ/YAP and screen novel biomarkers in KIRC. GSE121689 and GSE146354 were downloaded from the GEO. The limma was applied to identify the differential expression genes (DEGs) and the Venn diagram was utilized to screen co-expressed DEGs. Co-expressed DEGs obtained the corresponding pathways through GO and KEGG analysis. The protein-protein interaction (PPI) network was constructed using STRING. The hub genes were selected applying MCODE and CytoHubba. GSEA was further applied to identify the hub gene-related signaling pathways. The expression, survival, receiver operating character (ROC), and immune infiltration of the hub genes were analyzed by HPA, UALCAN, GEPIA, pROC, and TIMER. A total of 51 DEGs were co-expressed in the two datasets. The KEGG results showed that the enriched pathways were concentrated in the TGF-ß signaling pathway and endocytosis. In the PPI network, the hub genes (STAU2, AGO2, FMR1) were identified by the MCODE and CytoHubba. The GSEA results revealed that the hub genes were correlated with the signaling pathways of metabolism and immunomodulation. We found that STAU2 and FMR1 were weakly expressed in tumors and were negatively associated with the tumor stages. The overall survival (OS) and disease-free survival (DFS) rate of the high-expressed group of FMR1 was greater than that of the low-expressed group. The ROC result exhibited that FMR1 had certainly a predictive ability. The TIMER results indicated that FMR1 was positively correlated to immune cell infiltration. The abovementioned results indicated that TAZ/YAP was involved in the TGF-ß signaling pathway and endocytosis. FMR1 possibly served as an immune-related novel prognostic gene in KIRC.

Analysis of PANoptosis-Related LncRNA-miRNA-mRNA Network Reveals LncRNA SNHG7 Involved in Chemo-Resistance in Colon Adenocarcinoma.

Colon adenocarcinoma (COAD) is one of the most common malignancies, and its metastatic lesions are the leading cause of death in COAD patients. PANoptosis is a recently identified pathway for programmed cell death implicated in developing COAD. Long non-coding RNAs (lncRNAs) are key regulators of cancer occurrence and progress. Although their function has captured much attention in COAD, the relationship between COAD metastasis-associated lncRNA expression and PANoptosis remains elusive. Therefore, this study aimed to explore the potential regulatory roles of metastasis- and PANoptosis-associated lncRNAs in COAD. Nine lncRNAs associated with metastasis and PANoptosis in COAD were identified from The Cancer Genome Atlas (TCGA) and GEO databases. Their functions were analyzed by multiple bioinformatics methods, and the lncRNA-miRNA-mRNA network was constructed. Multivariate Cox analysis identified one lncRNA (SNHG7) significantly related to COAD prognosis. Subsequent analyses showed its expression correlated with tumor stage and lymph node metastasis. Moreover, drug sensitivity analysis and in vitro experiments suggest that lncRNA SNHG7 contributes to drug resistance in COAD. In summary, lncRNA SNHG7 is a potential target for diagnosing and treating COAD and plays a crucial role in regulating apoptosis, metastasis, and drug resistance in COAD.

Novel Circulating Tumour Cell-Related Risk Model Indicates Prognosis and Immune Infiltration in Lung Adenocarcinoma.

Background: Lung adenocarcinoma (LUAD) is the most common histological subtype of lung cancer (LC) and one of the leading causes of cancer-related death worldwide. LUAD has a low survival rate owing to tumour invasion and metastasis. Circulating tumour cells (CTCs) are precursors of distant metastasis, which are considered to adopt the characteristics of cancer stem cells (CSCs). Therefore, analysing the risk factors of LUAD from the perspective of CTCs may provide novel insights into the metastatic mechanisms and may help to develop diagnostic and therapeutic strategies. Methods: A total of 447 patients from TCGA dataset were included in the training cohort, and 460 patients from the GEO dataset were included in the validation cohort. A CTC-related-gene risk model was constructed using LASSO penalty-Cox analysis, and its predictive value was further verified. Functional enrichment analysis was performed on differentially expressed genes (DEGs), followed by immune correlation analysis based on the results. In addition, western blot, CCK-8 and colony formation assays were used to validate the biological function of RAB26 in LUAD. Results: A novel in-silico CTC-related-gene risk model, named the CTCR model, was constructed, which successfully divided patients into the high- and low-risk groups. The prognosis of the high-risk group was worse than that of the low-risk group. ROC analysis revealed that the risk model outperformed traditional clinical markers in predicting the prognosis of patients with LUAD. Further study demonstrated that the identified DEGs were significantly enriched in immune-related pathways. The immune score of the low-risk group was higher than that of the high-risk group. In addition, RAB26 was found to promote the proliferation of LUAD. Conclusion: A prognostic risk model based on CTC-related genes was successfully constructed, and the relationship between DEGs and tumour immunity was analysed. In addition, RAB26 was found to promote the proliferation of LUAD cells.

FOXP3 Contributes to TMZ Resistance, Prognosis, and Immune Infiltration in GBM from a Novel Pyroptosis-Associated Risk Signature.

Background: Pyroptosis is a form of programmed cell death, playing a significant role in cancer. Glioblastoma multiforme (GBM) is the most common malignant brain tumor. The poor prognosis in GBM due to temozolomide (TMZ) resistance has been widely discussed. Such being the case, the correlation between TMZ resistance and pyroptosis is seldom investigated. On this basis, this paper aims to explore the potential prognostic value of genes related to TMZ resistance and pyroptosis as well as their relationship to the immune microenvironment in GBM. Methods: A total of 103 patients from TCGA were assigned to a training cohort; 190 from CGGA were assigned to a validation cohort. The prognostic risk model reflecting pyroptosis and TMZ resistance was built from the training cohort using multivariate Cox regression and performed validation. RT-qPCR was used to examine the expression of 4 genes from the risk signature. FOXP3 was selected for overexpression and verified using the western blot. The TMZ IC50 of FOXP3-overexpressed cell lines was determined by CCK8. Results: A four genes-based risk signature was established and validated, separating GBM patients into high- and low-risk groups. Compared with the low-risk group, the high-risk group presented worse clinical survival outcomes. Its differential expressed genes were enriched in immune-related pathways and closely related to the immune microenvironment. Moreover, RT-qPCR results suggested that FOXP3, IRF3, and CD274 were significantly upregulated in TMZ-resistant strains, while TP63 was downregulated. FOXP3-overexpressed GBM cell lines had higher TMZ IC50, implying an increased resistance of TMZ. Conclusion: A novel gene signature relevant to pyroptosis and TMZ resistance was constructed and could be used for the prognosis of GBM. The four genes from the risk model might play a potential role in antitumor immunity and serve as therapeutic targets for GBM.

The roles of GTPase-activating proteins in regulated cell death and tumor immunity.

GTPase-activating protein (GAP) is a negative regulator of GTPase protein that is thought to promote the conversion of the active GTPase-GTP form to the GTPase-GDP form. Based on its ability to regulate GTPase proteins and other domains, GAPs are directly or indirectly involved in various cell requirement processes. We reviewed the existing evidence of GAPs regulating regulated cell death (RCD), mainly apoptosis and autophagy, as well as some novel RCDs, with particular attention to their association in diseases, especially cancer. We also considered that GAPs could affect tumor immunity and attempted to link GAPs, RCD and tumor immunity. A deeper understanding of the GAPs for regulating these processes could lead to the discovery of new therapeutic targets to avoid pathologic cell loss or to mediate cancer cell death.

Enhanced pyrethroid potency in Drosophila melanogaster expressing voltage-gated potassium channel mutants: Insecticidal activity and neuronal action.

Previous studies have shown that blockers of voltage-gated potassium (Kv) channels, such as 4-aminopyridine (4-AP) and 2-methoxy-N-((1-phenylcyclopentyl)methyl)benzamide (2-MPB) synergized pyrethroid toxicity as well, or better than, piperonyl butoxide. The present study assessed the involvement of different Kv channels as possible pyrethroid synergist targets in Drosophila melanogaster. Three Kv1 mutants (Sh5, Sh133, and ShM) and one Kv2 mutant (Shab3) were tested. All Kv1 mutant flies showed increased sensitivity to permethrin in topical and glass contact toxicity assays, of 2- to 11-fold. Central nervous system (CNS) recordings of larval D. melanogaster showed a similar pattern of increased sensitivity. Potentiated effects were also observed with deltamethrin on the mutants Sh5 (30- to 35-fold) and Sh133 (33- to 47-fold), but the mutant ShM showed little change in sensitivity. In contrast, the Shab3 strain showed toxicity and physiological effects of both pyrethroids that were similar to the susceptible OR strain. Thus, some K+ channel mutations mimicked the synergistic effect of channel blockers. Additional studies showed that Shab3 had the highest sensitivity to 4-AP in topical assays, and the Shaker-null mutants, ShM and Sh133 showed greater sensitivity to 2-MPB in CNS recordings of larval D. melanogaster. These results suggest that Kv1 channels are a useful synergist target for pyrethroids, as assessed both in whole insects and at the level of the nervous system. Thus, Kv1-targeting compounds can potentially serve as insect control tools to reduce pyrethroid use via synergistic action.

Resistance-Breaking Insecticidal Activity of New Spatial Insecticides against Aedes aegypti.

The use of N-aryl amide derivatives as spatially acting insecticides remains relatively unexplored. To expand this knowledge, we synthesized eighty-nine N-aryl amide analogues and screened them for mortality against an insecticide-susceptible strain of Aedes aegypti mosquitoes, Orlando (OR), using a vapor exposure glass tube assay. Of the screened compounds, twenty-two produced >92% mortality at 24 h and warranted further investigation to determine LC50 values. Fifteen of these analogues had LC50 values within 2 orders of magnitude of transfluthrin, and of significant interest, N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-2,2,3,3,3-pentafluoropropanamide (compound 70) was nearly as potent as transfluthrin and exhibited greater toxicity than metofluthrin when screened against OR A. aegypti. Compounds exhibiting potent toxicity against OR A. aegypti or whose structure-activity relationship potentially offered beneficial insights into structure optimization were screened against the insecticide-resistant, Puerto Rico (PR), strain of A. Aegypti, and it was discovered that not only did these N-arylamides typically show little resistance, some such as N-(2,6-dichloropyridin-4-yl)-2,2,3,3,4,4,4-heptafluorobutanamide (compound 36) and 2,2,3,3,4,4,4-heptafluoro-N-(3,4,5-trifluorophenyl)butanamide (compound 40) were actually more potent against the PR mosquitoes. Due to this promising insecticidal activity, five compounds were administered orally to mice to determine acute oral rodent toxicity. All five compounds were found to have mouse oral toxicity LD50 values well above the minimum safe level as set by the Innovative Vector Control Consortium (50 mg/kg). In addition to the promising biological activity documented here, we report the structure-activity relationship analysis used to guide the derivatization approach taken and to further inform future efforts in the development of N-arylamides as potential resistance-breaking, spatially acting insecticides.

Bioactivities and modes of action of VUAA1.

BACKGROUND: The compound 2-((4-ethyl-5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)thio)-N-(4-ethylphenyl) acetamide (VUAA1) is reported to be an odorant receptor co-receptor (Orco) agonist in insects with potential use as an insect repellent. For this study, the biological activity of VUAA1 was investigated in several bioassays with Aedes aegypti, including adult contact, spatial repellency, and larval repellency assays, as well as topical, injection, and feeding toxicity assays. Neurophysiological action was further explored by analysis of fruit fly central nervous system firing, cockroach axon recordings, patch clamp analysis of Kv2 potassium channel, and acetylcholinesterase inhibition studies. Finally, the metabolic impact on the toxicity of VUAA1 was explored by applying it in combination with established metabolic synergists. RESULTS: In repellency and bite protection screens, VUAA1 showed little activity against adult mosquitoes, apparently due to its low volatility, since its effectiveness was increased by heating or mixing with transfluthrin acid and citronella oil. It did produce measurable repellency of mosquito larvae that was more potent than N,N-diethyl-m-toluamide (DEET). Overall, VUAA1 showed low acute toxicity to both insects and mice, and it was weakly synergized by triphenyl phosphate. There was no observed cross-resistance in a pyrethroid-resistant strain of Anopheles gambiae. VUAA1 showed a two-phase effect on the central nervous system, with neuroexcitation at 1 µmol L-1 and an inhibitory effect at 100 µmol L-1 that may relate to block of Kv2 potassium channels. CONCLUSIONS: VUAA1 presented low toxicity, similar to other insect repellents. Its limited solubility, low volatility, and resulting poor adult repellency without additional adjuvants may restrict the utility of VUAA1 in typical public health applications. © 2020 Society of Chemical Industry.

Synergistic effects of potassium channel blockers and pyrethroids: mosquitocidal activity and neuronal mode of action†.

BACKGROUND: The purpose of this research was to explore the possibility of co-applying pyrethroids (agonists of voltage-sensitive sodium channels) with potassium channel blockers in order to potentiate the neurological effects of pyrethroids on Anopheles gambiae. We hypothesized that the toxicity of pyrethroids caused by persistent sodium currents would be augmented by blockage of outward potassium current flow, which normally repolarizes the membrane potential during a nerve membrane action potential. RESULTS: Topical treatments with LD10 s (10% mortality doses) of synergists were given with pyrethroids. 2S-65465 (2S) showed the best synergism of permethrin (8.6-fold) and deltamethrin (7.2-fold), whereas piperonyl butoxide and 4-aminopyridine only showed 2.2- to 3.4-fold synergism with these pyrethroids. In electrophysiological recordings of Periplaneta americana giant axons, 2S (10 µm) and 4-AP (30 µm) caused multiple spikes after a single stimulation. Permethrin at 10 µm showed significant summating depolarization (4.5 ± 1.1 mV) after a train of ten stimuli were applied at 5 Hz, and deltamethrin at 0.03 µm showed significant membrane depolarization of 2.9 ± 0.4 mV without stimuli. 2S at 0.3 µm and 4-AP at 1-3 µm significantly synergized the effects of 3 µm permethrin and 0.01 µm deltamethrin. CONCLUSIONS: Co-application of potassium channel blockers 2S and 4-AP with pyrethroids can synergize the mosquitocidal activities on An. gambiae, and these activities are correlated with synergistic effects at the level of the nerve membrane. If deployed in the field, this approach can potentially reduce the amount of chemicals needed for effective control of mosquitoes. © 2020 Society of Chemical Industry.

Structure-Activity Relationship Analysis of Potential New Vapor-Active Insect Repellents.

A total of 115 aryl amides were synthesized and screened for vapor repellency against the Orlando (OR) strain of Aedes aegypti mosquitoes. Of these compounds, 29 had 1 h repellency EC50 values comparable to or better than N,N-diethyl-meta-toluamide (DEET, 1 h EC50 value of 35 µg/cm2), with 2,2,3,3,3-pentafluoro-N-(4-fluorophenyl)propenamide (53) and 2,2,3,3,4,4,4-heptafluoro-N-(3,4,5-trifluorophenyl)butanamide (101) exhibiting the most potent EC50 values of 4.5 and 2.9 µg/cm2, respectively. The cross-resistance of select, highly potent, derivatives against the pyrethroid-resistant Puerto Rico (PR) strain of A. aegypti was also investigated, and little to no resistance was observed. When synergized with 1R-trans-permethrinic acid (TFA), compound 101 had a 1 h EC50 value 6 times lower than metofluthrin against OR and 40 times lower against PR mosquitoes. Additionally, preliminary mammalian oral toxicity was screened for compounds 69 and 101, and both exhibited LD50 values of >2000 mg/kg. The structure-activity relationship analysis, which guided the synthesis of these derivatives, is given, and key trends are highlighted to inform future analogue design.