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Cincticostellajianchuan sp. nov. from Dali Bai Autonomous Prefecture, Yunnan Province, China, is described based on chorionic structure, nymph, and winged stages. The new species is closely related to C.fusca (Kang & Yang, 1995), but it can be distinguished in the male imago stage by its mesonotum and penes morphology, coloration, and the forking point of the stem of MA+Rs on the forewing; in the nymph stage, it can be distinguished by the length of the posterolateral projections of abdominal segment IX and the setation of the abdominal terga. Compared to other congeners, nymphs and male imagoes of the new species and C.fusca share several morphological characteristics, such as a larger body, mesothorax with medially notched anterolateral projections, forefemur without a subapical band of transverse spines of the nymphs, the area between C, Sc and R1 of the forewings distinctly pigmented, and an apical sclerite on the ventral face of the penes of the male imagoes, supporting the proposition of a new species complex, the jianchuan complex. The systematics of Cincticostella and related genera are discussed briefly.
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BACKGROUND: Malignant pleural effusion (MPE) is frequently observed in patients with advanced lung adenocarcinoma (LUAD). Pleural fluid cytology is a less invasive procedure compared to pleural biopsy. Therefore, it is crucial to identify novel effective biomarkers for LUAD-associated pleural fluid cytology. METHODS: The RNA sequencing (RNA-Seq) and clinical data of LUAD cases were downloaded from TCGA and OncoSG databases. Differential gene expression analysis, survival analysis and immune cell infiltration analysis were performed on the LUAD datasets. The expression levels of FAM83A, TFF-1, and NapsinA in 94 paired LUAD and adjacent normal tissues, and in the pleural effusion specimens of 40 LUAD and 21 non-neoplastic patients were evaluated by immunohistochemistry. RESULTS: FAM83A expression levels were significantly different between the LUAD and normal tissue datasets, and correlated with overall or disease-free survival, and histological grade of the tumors. Furthermore, the in-situ expression of FAM83A was higher in 89/94 LUAD tissues compared to the paired normal tissues. FAM83A expression was significantly correlated with immune cell infiltration, and showed a positive association with macrophage infiltration. In addition, FAM83A staining was positive in 37 LUAD pleural effusion samples, and negative in 20 non-neoplastic pleural effusion samples. The expression pattern of FAM83A in the pleural effusion of LUAD patients was relatively consistent with that of TFF-1 and NapsinA, and even stronger in some specimens that were weakly positive or negative for TTF1/NapsinA. CONCLUSIONS: FAM83A is a promising immune-related biomarker in LUAD biopsy specimens and pleural fluid, and can distinguish between malignant and benign pleural effusion.
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BACKGROUND: Focusing on the complicated pathological features, such as blurred boundaries, severe scale differences between symptoms, and background noise interference, we aim to enhance the reliability of multiple lesions joint segmentation from medical images. PURPOSE: Propose a novel reliable multi-scale wavelet-enhanced transformer network, which can provide accurate segmentation results with reliability assessment. METHODS: Focusing on enhancing the model's capability to capture intricate pathological features in medical images, this work introduces a novel segmentation backbone. The backbone integrates a wavelet-enhanced feature extractor network and incorporates a multi-scale transformer module developed within the scope of this work. Simultaneously, to enhance the reliability of segmentation outcomes, a novel uncertainty segmentation head is proposed. This segmentation head is rooted in the SL, contributing to the generation of final segmentation results along with an associated overall uncertainty evaluation score map. RESULTS: Comprehensive experiments are conducted on the public database of AI-Challenge 2018 for retinal edema lesions segmentation and the segmentation of Thoracic Organs at Risk in CT images. The experimental results highlight the superior segmentation accuracy and heightened reliability achieved by the proposed method in comparison to other state-of-the-art segmentation approaches. CONCLUSIONS: Unlike previous segmentation methods, the proposed approach can produce reliable segmentation results with an estimated uncertainty and higher accuracy, enhancing the overall reliability of the model. The code will be release on https://github.com/LooKing9218/ReMultiSeg.
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[This corrects the article DOI: 10.3389/fonc.2024.1327851.].
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Background: Cervical cancer is currently the second leading cause of cancer death among women from developing countries (1). However, there is a lack of effective treatment methods, and the existing treatments often result in significant adverse reactions and high chances of recurrence, which ultimately impact the prognosis of patients. As a result, the application of nanotechnology, specifically nanoparticle-based approaches, in the diagnosis and treatment of cervical cancer has gained significant attention. This study aims to examine the current research status and future development trends of nanotechnology in relation to cervical cancer using a bibliometric perspective. Methods: A bibliometric analysis was performed to gather relevant research papers from the Web of Science database. VOSviewer and CiteSpace were utilized to conduct quantitative analysis and identify hot topics in the field, focusing on countries, institutions, journals, authors, and keywords. Result: A total of 997 eligible literature were retrieved. From January 1, 2014 to September 20, 2023, the overall number of publications showed an upward trend. The paper mainly comes from China (n=414). The main institution is the Chinese Academy of Sciences (n=62), and 60% of the top 10 institutions in the number of documents issued are from China. First authors Ma, Rong (n=12) and Alifu, Nuernisha (n=12). The journal with the highest publication volume is ACS Applied Materials&INTERFACES (n=35), and the journal with the highest citation frequency is BIOMATERIALS (n=508). "Nanoparticles (n=295)", "cervical cancer (n=248)", and "drug delivery (n=218)" are the top three most frequently occurring keywords. In recent years, photothermal therapy and indocyanine green have become research hotspots. Conclusion: The application of nanotechnology in the field of cervical cancer has garnered considerable attention. Nanoparticles-based methods for diagnosis, administration, and treatment have proven to be instrumental in enhancing the sensitivity of cervical cancer detection, improving the accuracy and efficiency of administration, and reducing drug toxicity. Enhancing treatment efficacy and improving patient prognosis have emerged as current research priorities and future directions.
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Optical coherence tomography (OCT) images are inevitably affected by speckle noise because OCT is based on low-coherence interference. Multi-frame averaging is one of the effective methods to reduce speckle noise. Before averaging, the misalignment between images must be calibrated. In this paper, in order to reduce misalignment between images caused during the acquisition, a novel multi-scale fusion and Transformer based (MsFTMorph) method is proposed for deformable retinal OCT image registration. The proposed method captures global connectivity and locality with convolutional vision transformer and also incorporates a multi-resolution fusion strategy for learning the global affine transformation. Comparative experiments with other state-of-the-art registration methods demonstrate that the proposed method achieves higher registration accuracy. Guided by the registration, subsequent multi-frame averaging shows better results in speckle noise reduction. The noise is suppressed while the edges can be preserved. In addition, our proposed method has strong cross-domain generalization, which can be directly applied to images acquired by different scanners with different modes.
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Retina , Tomografía de Coherencia Óptica , Tomografía de Coherencia Óptica/métodos , Retina/diagnóstico por imagenRESUMEN
An experiment of 12C(16O,16O â 4α)12C was performed at a beam energy of 96 MeV. A large number of 4-α events were recorded in coincidence and with full particle identification (PID). This was made possible by employing a series of silicon-strip-based telescopes that provided excellent position and energy resolutions. Four narrow resonances just above the 15.1 MeV state were firmly identified in the α + 12C(7.65 MeV; Hoyle state) decay channel. Combined with the theoretical predictions, these resonant states provide new evidence for the predicted possible Hoyle-like structure in 16O above the 4-α separation threshold. Some very high-lying 4-α resonant states have also been observed and need to be further investigated.
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Registros , Telescopios , Silicio , VibraciónRESUMEN
Proper estimation of the cup-to-disc ratio (C/D ratio) plays a significant role in ophthalmic examinations, and it is urgent to improve the efficiency of C/D ratio automatic measurement. Therefore, we propose a new method for measuring the C/D ratio of OCTs in normal subjects. Firstly, the end-to-end deep convolution network is used to segment and detect the inner limiting membrane (ILM) and the two Bruch's membrane opening (BMO) terminations. Then, we introduce an ellipse fitting technique to post-process the edge of the optic disc. Finally, the proposed method is evaluated on 41 normal subjects using the optic-disc-area scanning mode of three machines: BV1000, Topcon 3D OCT-1, and Nidek ARK-1. In addition, pairwise correlation analyses are carried out to compare the C/D ratio measurement method of BV1000 to existing commercial OCT machines as well as other state-of-the-art methods. The correlation coefficient between the C/D ratio calculated by BV1000 and the C/D ratio calculated by manual annotation is 0.84, which indicates that the proposed method has a strong correlation with the results of manual annotation by ophthalmologists. Moreover, in comparison between BV1000, Topcon and Nidek in practical screening among normal subjects, the proportion of the C/D ratio less than 0.6 calculated by BV1000 accounts for 96.34%, which is the closest to the clinical statistics among the three OCT machines. The above experimental results and analysis show that the proposed method performs well in cup and disc detection and C/D ratio measurement, and compared with the existing commercial OCT equipment, the C/D ratio measurement results are relatively close to reality, which has certain clinical application value.
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Disco Óptico , Tomografía de Coherencia Óptica , Humanos , Tomografía de Coherencia Óptica/métodos , Lámina Basal de la CoroidesRESUMEN
In the fiber Bragg grating (FBG) sensor network, the signal resolution of the reflected spectrum is correlated with the network's sensing accuracy. The interrogator determines the signal resolution limits, and a coarser resolution results in an enormous uncertainty in sensing measurement. In addition, the multi-peak signals from the FBG sensor network are often overlapped; this increases the complexity of the resolution enhancement task, especially when the signals have a low signal-to-noise ratio (SNR). Here, we show that deep learning with U-Net architecture can enhance the signal resolution for interrogating the FBG sensor network without hardware modifications. The signal resolution is effectively enhanced by 100 times with an average root mean square error (RMSE) < 2.25 pm. The proposed model, therefore, allows the existing low-resolution interrogator in the FBG setup to function as though it contains a much higher-resolution interrogator.
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Keratoconus (KC) is a noninflammatory ectatic disease characterized by progressive thinning and an apical cone-shaped protrusion of the cornea. In recent years, more and more researchers have been committed to automatic and semi-automatic KC detection based on corneal topography. However, there are few studies about the severity grading of KC, which is particularly important for the treatment of KC. In this work, we propose a lightweight KC grading network (LKG-Net) for 4-level KC grading (Normal, Mild, Moderate, and Severe). First of all, we use depth-wise separable convolution to design a novel feature extraction block based on the self-attention mechanism, which can not only extract rich features but also reduce feature redundancy and greatly reduce the number of parameters. Then, to improve the model performance, a multi-level feature fusion module is proposed to fuse features from the upper and lower levels to obtain more abundant and effective features. The proposed LKG-Net was evaluated on the corneal topography of 488 eyes from 281 people with 4-fold cross-validation. Compared with other state-of-the-art classification methods, the proposed method achieves 89.55% for weighted recall (W_R), 89.98% for weighted precision (W_P), 89.50% for weighted F1 score (W_F1) and 94.38% for Kappa, respectively. In addition, the LKG-Net is also evaluated on KC screening, and the experimental results show the effectiveness.
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Environmental degradation is a global ecological concern, and land use transitions play a critical role in a region's ecological well-being and long-term sustainability. In this paper, indicators related to land use transitions, including the regional eco-environmental quality index (EV), the remote sensing ecological index (RSEI), and soil erosion, are selected to analyze the eco-environmental quality of Erhai Lake Basin from 2000 to 2020. The results showed that (1) from 2000 to 2020, forestland, grassland, and cultivated land were the major land use types in the study region, and also the land use types where land use transition was notable; (2) over the 20 years of study, the EV value of Erhai Lake Basin increased by 0.003, its average RSEI increased by 0.14, and the average soil erosion modulus there decreased by 15.48 t/(km2·a), indicating that the eco-environment of the Erhai Lake Basin was improving. Evaluation based on multiple ecological indicators was superior to assessment relying on single indicators; (3) all three ecological indicators showed that the ecological environment of the basin was improving, but with significant regional differences. Forestland had the best ecological quality, while unused land and built-up land had the worst. RSEI was more regionally adaptable than the other two indices. (4) The transition of cultivated land into other land use types was the main reason for the improved ecological quality in the basin, while tourism had accelerated land use transformation. Compared with assessment based on single ecological indicators, evaluation based on a combination of multiple ecological indicators can more accurately reflect the ecological condition of the study area and provide a basis for eco-environmental protection in Erhai Lake Basin.
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Ecosistema , Indicadores Ambientales , Lagos , Bosques , Conservación de los Recursos Naturales , China , Monitoreo del AmbienteRESUMEN
RATIONALE: Genotypic and histological evolution of non-small-cell lung cancer (NSCLC) into small-cell lung cancer (SCLC) has been described as a mechanism of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy. However, the number of clinical cases is rare. PATIENT CONCERNS: Two lung adenocarcinoma patients with EGFR mutations who recurred after radical resection transformed into SCLC under treatment with the sequential first- and third-generation EGFR-TKIs. DIAGNOSIS: The 2 cases were both confirmed as SCLC by pathological rebiopsy after EGFR-TKIs resistance. INTERVENTIONS: Case 1 was treated with etoposide plus cisplatin (EP) regimen and erlotinib, while case 2 was treated with erlotinib and EP followed by oral etoposide. OUTCOMES: Case 1 treated with EP only achieved 3-month progression-free survival (PFS), which is the first case that reported T790âM/C797S cis-mutation for osimertinib resistance before the SCLC transformation. However, case 2 treated with erlotinib and EP followed by oral etoposide, PFS lasted for 8âmonths. LESSONS: The cases highlighted the importance of rebiopsy that identified pathologically SCLC transformation after EGFR-TKI resistance, and suggested the treatment of erlotinib plus EP followed by etoposide, which could provide a reference for such phenotype.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/terapia , Neoplasias Pulmonares/patología , Recurrencia Local de Neoplasia/terapia , Inhibidores de Proteínas Quinasas/farmacología , Carcinoma Pulmonar de Células Pequeñas/terapia , Acrilamidas/farmacología , Acrilamidas/uso terapéutico , Adulto , Compuestos de Anilina/farmacología , Compuestos de Anilina/uso terapéutico , Biopsia , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Cisplatino/uso terapéutico , Resistencia a Antineoplásicos/efectos de los fármacos , Epirrubicina/uso terapéutico , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/genética , Clorhidrato de Erlotinib/uso terapéutico , Resultado Fatal , Femenino , Humanos , Pulmón/diagnóstico por imagen , Pulmón/patología , Pulmón/cirugía , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/terapia , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/diagnóstico , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/patología , Neumonectomía , Inhibidores de Proteínas Quinasas/uso terapéutico , Carcinoma Pulmonar de Células Pequeñas/diagnóstico , Carcinoma Pulmonar de Células Pequeñas/genética , Carcinoma Pulmonar de Células Pequeñas/patología , Tomografía Computarizada por Rayos X , Resultado del TratamientoRESUMEN
In quasi-distributed fiber Bragg grating (FBG) sensor networks, challenges are known to arise when signals are highly overlapped and thus hard to separate, giving rise to substantial error in signal demodulation. We propose a multi-peak detection deep learning model based on a dilated convolutional neural network (CNN) that overcomes this problem, achieving extremely low error in signal demodulation even for highly overlapped signals. We show that our FBG demodulation scheme enhances the network multiplexing capability, detection accuracy and detection time of the FBG sensor network, achieving a root-mean-square (RMS) error in peak wavelength determination of < 0.05 pm, with a demodulation time of 15â ms for two signals. Our demodulation scheme is also robust against noise, achieving an RMS error of < 0.47 pm even with a signal-to-noise ratio as low as 15â dB. A comparison on our high-performance computer with existing signal demodulation methods shows the superiority in RMS error of our dilated CNN implementation. Our findings pave the way to faster and more accurate signal demodulation methods, and testify to the substantial promise of neural network algorithms in signal demodulation problems.
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PURPOSE: An anatomical and histological study of the conjoint fascial sheath of the levator and superior rectus (CFS) was carried out by using the cadavers for teaching. METHODS: Three adult Asian cadaver heads fixed in formalin were used. The CFS was exposed by the same surgeon in each case. Then the CFS was observed and measured in vivo and ex vivo. And the CFS, the levator and the frontal muscle were removed from the same eye for histological study. RESULTS: The CFS was located 2.1 ± 0.4 mm posterior to the fornix. A special muscle sheath of the levator was observed. The special muscle sheath and the tendon of the superior rectus were fused to the CFS through loose connective tissue. Hematoxylin-Eosin (HE) staining showed a large amount of connective tissue on examination of the CFS by microscopy. Double staining with Victoria-blue and Masson trichrome staining confirmed elastic fibers and collagen fibers in the CFS tissues. CONCLUSIONS: If ptosis correction surgery is performed by looking for the CFS from the upper edge of the conjunctiva, in fact, only a special part of the muscle sheath of the levator in the CFS, but not the integral CFS, is used in the surgery. The histological results confirm that the CFS is a fibrous tissue membrane with both elasticity and toughness. Perhaps the best choice is to recombine the special muscle sheath of the levator in the CFS with the levator muscle tissue during ptosis correction surgery to suspend the eyelids.
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Blefaroplastia , Blefaroptosis , Adulto , Blefaroptosis/cirugía , Párpados/cirugía , Fascia , Humanos , Músculos Oculomotores/cirugíaRESUMEN
Intron detention in precursor RNAs serves to regulate expression of a substantial fraction of genes in eukaryotic genomes. How detained intron (DI) splicing is controlled is poorly understood. Here, we show that a ubiquitous post-translational modification called O-GlcNAc, which is thought to integrate signaling pathways as nutrient conditions fluctuate, controls detained intron splicing. Using specific inhibitors of the enzyme that installs O-GlcNAc (O-GlcNAc transferase, or OGT) and the enzyme that removes O-GlcNAc (O-GlcNAcase, or OGA), we first show that O-GlcNAc regulates splicing of the highly conserved detained introns in OGT and OGA to control mRNA abundance in order to buffer O-GlcNAc changes. We show that OGT and OGA represent two distinct paradigms for how DI splicing can control gene expression. We also show that when DI splicing of the O-GlcNAc-cycling genes fails to restore O-GlcNAc homeostasis, there is a global change in detained intron levels. Strikingly, almost all detained introns are spliced more efficiently when O-GlcNAc levels are low, yet other alternative splicing pathways change minimally. Our results demonstrate that O-GlcNAc controls detained intron splicing to tune system-wide gene expression, providing a means to couple nutrient conditions to the cell's transcriptional regime.
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Acetilglucosamina/metabolismo , Glicósido Hidrolasas/genética , Intrones , N-Acetilglucosaminiltransferasas/genética , Empalme del ARN , Línea Celular , Glicósido Hidrolasas/metabolismo , Células HEK293 , Humanos , N-Acetilglucosaminiltransferasas/antagonistas & inhibidores , N-Acetilglucosaminiltransferasas/metabolismo , Fosforilación , Factores de Empalme de ARN/metabolismo , ARN Mensajero/metabolismo , RNA-SeqRESUMEN
Reversible glycosylation of nuclear and cytoplasmic proteins is an important regulatory mechanism across metazoans. One enzyme, O-linked N-acetylglucosamine transferase (OGT), is responsible for all nucleocytoplasmic glycosylation and there is a well-known need for potent, cell-permeable inhibitors to interrogate OGT function. Here we report the structure-based evolution of OGT inhibitors culminating in compounds with low nanomolar inhibitory potency and on-target cellular activity. In addition to disclosing useful OGT inhibitors, the structures we report provide insight into how to inhibit glycosyltransferases, a family of enzymes that has been notoriously refractory to inhibitor development.
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Diseño de Fármacos , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , N-Acetilglucosaminiltransferasas/antagonistas & inhibidores , Células HCT116 , Células HEK293 , Humanos , Simulación del Acoplamiento Molecular , N-Acetilglucosaminiltransferasas/química , N-Acetilglucosaminiltransferasas/metabolismo , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacologíaRESUMEN
A convenient route to convert the highly toxic phosphine (PH3) tail gas into high-performance polybenzoxazines was first described in this paper. Two aliphatic polyamines, namely tris(aminomethyl)phosphine oxide and bis(aminomethyl)phenylphosphine oxide, were synthesized from tetrakis(hydroxymethyl)phosphonium sulfate (THPS), a green derivative of PH3 tail gas. And then two novel phosphorus-containing benzoxazine monomers, tris(3,4-dihydro-2H-1,3-benzoxazin-3-yl-methyl)phosphine oxide (TBOz) and benzylbis(3,4-dihydro-2H-1,3-benzoxazin-3-yl-methyl) phosphine oxide (BBOz) were prepared by three-steps procedure. FT-IR and DSC technologies were adopted to study the thermal-initiated polymerization behaviors of two benzoxazine monomers. Thermal properties of these crosslinked polymers were studied by TGA and DMA. The results display that the polybenzoxazines (PTBOz and PBBOz) exhibite good thermal stabilities and high glass transition temperatures. The char yield of polybanzoxazine is high as 47% and indiactes that phosphorus-containing polybenzoxazines show high fire-retardancy. The surface free energies of the PTBOz and PBBOz are 37.1 and 40.4mJm-2 by Owens two-liquid method. The dielectric properties of the PTBOz and PBBOz remaine near constant in the experimental frequency range.
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Long-term interannual (1991-2013) and monthly (1999-2013) data were analyzed to elucidate the effects of meteorological factors and nutrient levels on phytoplankton biomass in the cyanobacteria-dominated Waihai basin of Lake Dianchi. The interannual ln(chl. a) exhibited positive correlations with the mean air temperature, mean minimum air temperature, and mean maximum air temperature; in addition, a positive relationship between Δln(chl. a) and ΔTP was observed throughout the period. Additionally, ln(chl. a) exhibited a positive correlation with the TP concentration, negative correlations with the sunshine hours and wind speed during the dry season, and positive correlations with the TN and TP concentrations during the rainy season. Furthermore, TP was the most influential factor affecting cyanobacterial bloom dynamics throughout the entire period and during the dry season, and TN and TP were the most important factors during the rainy season, as determined by relative importance analysis. The results of this study based on interannual analysis demonstrated that both meteorological factors and nutrient levels have important roles in controlling cyanobacterial bloom dynamics. The relative importance of these factors may change according to precipitation patterns. Thus, climate change regulation and eutrophication management should be considered in strategies for bloom control. Decreasing the TP load should be prioritized throughout the entire period and during the dry season, and decreasing the TN and TP loads should be considered initially during the rainy season. In addition, further studies of more frequent and complete data acquired over a longer period of time should be conducted in the future.
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Cambio Climático , Cianobacterias , Fitoplancton , Biomasa , China , Lagos , Lluvia , Estaciones del Año , VientoRESUMEN
O-GlcNAc transferase (OGT) is an essential mammalian enzyme that regulates numerous cellular processes through the attachment of O-linked N-acetylglucosamine (O-GlcNAc) residues to nuclear and cytoplasmic proteins. Its targets include kinases, phosphatases, transcription factors, histones, and many other intracellular proteins. The biology of O-GlcNAc modification is still not well understood, and cell-permeable inhibitors of OGT are needed both as research tools and for validating OGT as a therapeutic target. Here, we report a small molecule OGT inhibitor, OSMI-1, developed from a high-throughput screening hit. It is cell-permeable and inhibits protein O-GlcNAcylation in several mammalian cell lines without qualitatively altering cell surface N- or O-linked glycans. The development of this molecule validates high-throughput screening approaches for the discovery of glycosyltransferase inhibitors, and further optimization of this scaffold may lead to yet more potent OGT inhibitors useful for studying OGT in animal models.
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Inhibidores Enzimáticos/farmacología , N-Acetilglucosaminiltransferasas/antagonistas & inhibidores , Bibliotecas de Moléculas Pequeñas/farmacología , Animales , Células CHO , Permeabilidad de la Membrana Celular , Cricetulus , Inhibidores Enzimáticos/síntesis química , Ensayos Analíticos de Alto Rendimiento , Humanos , Concentración 50 Inhibidora , Lectinas/química , Lectinas/metabolismo , N-Acetilglucosaminiltransferasas/química , N-Acetilglucosaminiltransferasas/metabolismo , Bibliotecas de Moléculas Pequeñas/síntesis química , Uridina Difosfato/química , Uridina Difosfato/metabolismo , Uridina Difosfato N-Acetilglucosamina/química , Uridina Difosfato N-Acetilglucosamina/metabolismoRESUMEN
The sulphur aroma compounds produced from a phosphate-buffered solution (pH 8) of l-cysteine and l-, l-[1-13C] or l-[4-13C] ascorbic acid, heated at 140±2°C for 2h, were examined by headspace SPME in combination with GC-MS. MS data indicated that C-1 of l-ascorbic acid was not involved in the formation of sulphur aroma compounds. The sulphur aroma compounds formed by reaction of l-ascorbic acid with l-cysteine mainly contained thiophenes, thiazoles and sulphur-containing alicyclic compounds. Among these compounds, 1-butanethiol, diethyl disulphide, 5-ethyl-2-methylthiazole, cis and trans-3,5-dimethyl-1,2,4-trithiolane, thieno[2,3-b]thiophene, thieno[3,2-b]thiophene, cis and trans-3,5-diethyl-1,2,4-trithiolane, 1,2,5,6-tetrathiocane, 2-ethylthieno[2,3-b]thiophene, 2,4,6-trimethyl-1,3,5-trithiane and cyclic octaatomic sulphur (S8) were formed solely by l-cysteine degradation, and the rest by reaction of l-ascorbic acid degradation products, such as hydroxybutanedione, butanedione, acetaldehyde, acetol, pyruvaldehyde and formaldehyde with l-cysteine or its degradation products, such as H2S and NH3. A new reaction pathway from l-ascorbic acid via its degradation products was proposed.