Hasil untuk "Microscopy"

G. Johnson, R. Davidson, K. McNamee et al.

N. Dudovich, D. Oron, Y. Silberberg

M. V. Rossum, T. Nieuwenhuizen

important corrections are presented. These corrections are calculated with the radiative transfer or Schwarzschild-Milne equation, which describes intensity transport at the ‘‘mesoscopic’’ level and is derived from the ‘‘microscopic’’ wave equation. A precise treatment of the diffuse intensity is derived which automatically includes the effects of boundary layers. Effects such as the enhanced backscatter cone and imaging of objects in opaque media are also discussed within this framework. This approach is extended to mesoscopic correlations between multiple scattered intensities that arise when scattering is strong. These correlations arise from the underlying wave character. The derivation of correlation functions and intensity distribution functions is given and experimental data are discussed. Although the focus is on light scattering, the theory is also applicable to microwaves, sound waves, and noninteracting electrons. [S0034-6861(99)00601-7]

Feiya Li, Wei Wu, Kehan Wu et al.

Aim or purpose: Periodontitis is a chronic inflammatory disease caused by dental plaque biofilm. This work developes a novel nanocomposite Ti/Mn-MOF-PA by integrating piezoelectric bimetal-organic framework (MOF) nanosheets with phenylboric acid (PBA) and the nitric oxide donor arginine (Arg). The aim is to investigate its antibacterial effects and immune modulation, addressing challenges in deep periodontitis treatment. Materials and methods: Ti/Mn-MOF NSs were characterized by TEM, XRD, XPS and PFM. Sonodynamic activity, NO release, and stability were assessed by UV-Vis spectrophotometry. A computational analysis based on first-principles calculations was conducted. Adhesion of Ti/Mn-MOF-PA to P. gingivalis was analyzed by TEM, flow cytometry, and confocal microscopy. Antibacterial effect were determined by CFU counting, SEM, and live/dead staining. Immunomodulatory effects were studied by IF staining and q-PCR. In vivo inflammatory regulation was verified by imaging and histological staining. Microbial communities were identified by 16S rDNA sequencing. Results: 1.Ti/Mn-MOF-PA have excellent acoustic properties, controllable nitric oxide release, and strong piezoelectric performance.2. They could modulate immunity by inhibiting NLRP3 inflammasome assembly and suppressing NF-κB activation, kill bacteria, and disrupt biofilms. 3.In vivo studies show reduced inflammation by lowering inflammatory factors and collagen degradation. Conclusions: Ti/Mn-MOF-PA nanocomposites exhibit strong acoustic dynamics, controlled NO release, and piezoelectric properties, which help kill bacteria, disrupt biofilms, reduce the release of inflammatory factors.By targeting subgingival pathogens and restoring microbiota balance they show robust antibacterial and anti-inflammatory effects in vivo.

Jie Ma, Jinjin Liu, Yuqi Huo

Abstract The N-terminal cleavage of the norovirus major capsid protein VP1 during in vitro expression is a widely observed phenomenon, yet the underlying mechanisms remain poorly understood. This study aimed to determine how N-terminal insertion sequences affect the cleavage and assembly of virus-like particles (VLPs). To this end, a series of recombinant GII.6 VP1 proteins with varied N-terminal insertion peptides were constructed and expressed using a baculovirus expression system. The expression, integrity, and assembly status of these proteins were analyzed using Western blot (WB), SDS-PAGE, transmission electron microscopy (TEM), and peptide fingerprinting analysis. Furthermore, a recombinant protein with a N-terminal FLAG tag was also constructed and expressed to investigate the characteristics of N-terminal cleavage. Our findings indicate that varied N-terminal insertion peptides produced different cleavage patterns with some peptide sequences showing inhibition of N-terminal cleavage. N-terminal FLAG-tagged fragment was not detected in cell lysate, further suggesting the complexity of the N-terminal cleavage. These results provide new insights into the molecular mechanisms of VP1 processing and its implications for virus-like particle (VLP) assembly.

Pamela I. Pérez-Martínez, Viridiana Gutiérrez-Espinosa, Christian Ávalos-Gómez et al.

Lactic acid bacteria are components of the gastrointestinal tract microbiota in both humans and animals and are widely used as probiotics. <i>Lactobacillus</i> is the most closely related genus to probiotic activity. It is capable of releasing membrane microvesicles (MVs), whose primary functions include carrying and transmitting antigens to host tissues and modulating host defense responses. In the present study, MVs were isolated from <i>Lactobacillus acidophilus</i> resident in the ileum of free-living rats, and their immunostimulant effect was evaluated in two biological models. MVs were characterized using SDS-PAGE electrophoresis, electron microscopy, and nanoparticle tracking analysis. In the first model, the immunostimulatory effect of MVs was evaluated on ovine abomasal explants, which had been previously stimulated with MVs and then challenged with third-stage larvae of <i>Haemonchus contortus</i>. This resulted in a decrease in the percentage of larval association and favored the migration of inflammatory cells to the infection site. In the second model, the macrophage cell line RAW 264.7 was stimulated with MVs to evaluate the expression of transcripts encoding IL-1β and TNF-α. MVs isolated from <i>L. acidophilus</i> demonstrate immunostimulatory and probiotic effects in the two biological models assessed. This suggested that the MVs possess similar immunostimulatory effects as those reported for the parent bacteria.

A.M. Гринько, А.В. Бричка, О.М. Бакалінська et al.

Nanoceria was synthesized by reaction of cerium nitrate deposition in an aqueous medium without stabilizers at room temperature. Nano-sized cerium oxide was dried at 20 °C and calcinated in air for 1 hour at 120, 300, 500, 800 °C. SEM images of samples demonstrated that the morphology of the obtained cerium oxide does not significantly change with the increase of the temperature of heat treatment. Electron microscopy showed that the average diameter of CeO2 particles varies in the range of 12.4–15.9 nm. Sample element content was determined by the energy-dispersive X-ray spectrometry method. The Oxygen:Cerium elements ratio in the samples is in the range 1.7–2.1. X-Ray Diffraction method was used to determine the structural characteristics of materials. It was demonstrated that with increasing annealing temperature, the average crystallite diameter increases from 10 to 23 nm, and the degree of crystallinity changes from 60 % for Ce-20 to 100 % for Ce-800. The characteristics of the porous structure were determined based on low-temperature nitrogen adsorption/desorption isotherms. The specific surface area (BET) of the samples heated to 500 °C varies within 46–61 m2/g. The total pore volume varies from 0.19 to 0.22 cm3/g. After heating to 800 °C, the specific surface area and total pore volume decrease to 17 m2/g and 0.13 cm3/g, respectively. By TGA method was found that 5 % mass loss between 20 and 300 °C is attributed to adsorbed water, while 9 % starting at around 500 °C refers to release from the surface of chemically bonded water molecules. The IUVS Ce4+/IUVS Ce3+ ratio in samples was found from UV-spectra of diffuse reflectance; it varied in the range of 1.60 to 2.08. Calcination of nanoceria samples at temperatures above 500 °C leads to the oxidation of Ce3+ to Ce4+ and reduction of nanoceriа surface defects. The catalytic activity of the synthesized materials was evaluated by the determination of the reaction rate constant (k) of the H2O2 decomposition reaction at the different concentrations (1–10 %) at room temperature and within pH 8.0–11.0. Materials calcinated at different temperatures demonstrate maximum catalytic activity at pH 10.0, which is determined by the increase in the content of deprotonated ceranol groups on the surface of cerium oxide with an increase in the pH from 8.0 to 10.0, and the formation of insoluble Cerium compounds with a further increase in pH. The activation energy (Ea) of the reaction of hydrogen peroxide decomposition by nanoceria in the temperature range of 20–40 °C at pH 10 was determined by kinetic data. The Ea for un-annealing sample Ce-20 is 127 kJ/mol. Increasing temperature to 120 °C does not change the Ea. It was shown that the smallest value of activation energy is 77 kJ/mol for the sample calcinated at 300 °C. Heating the samples at temperatures 500 and 800 °C causes growth of Ea – to 94 and 95 kJ/mol, respectively. We did not find correlation between degree of crystallinity, specific surface area, total pore volume, crystallite size and calcinated samples catalytic activity. The dependence of the rate constant (activity) on the calcination temperature is extreme with a maximum at 300 °C was found. A sample Ce-300, which has the highest O:Ce ratio (2.08), the largest O content (67.5 %), the lowest Ce4+/Ce3+ ratio (0.15) among the calcinated samples, and therefore the largest number of surface defects exhibits the highest catalytic activity and has the lowest activation energy for the hydrogen peroxide decomposition reaction. Presumably, when heating CeO2 samples, some parallel processes occur. Changes in the values of structural parameters either have no effect or are insignificant and also do not affect the catalytic activity of nanoceria. Desorption of physically adsorbed water, which inactivates the catalytic centers, leads to an increase in catalytic activity of the material. In addition, destruction of ceranol groups on the surface of cerium oxide with loss of oxygen and oxidation of Ce3+ to Ce4+ reduces catalytic activity.

Jaya Verma, Manish Sharma, Rajesh Kumari Manhas

Abstract Due to high resistance to medicines, multidrug-resistant (MDR) bacterial pathogens, particularly MRSA (methicillin-resistant Staphylococcus aureus) and VRE (vancomycin-resistant enterococci), are a significant public health concern for treating nosocomial infections. Researchers are developing novel compounds responding to the global rise in MDR infections. This study aimed to extract, purify, and characterize bioactive metabolites from Streptomyces levis strain HFM-2, a human gut isolate, exhibiting strong antimicrobial activity against several MDR pathogenic bacteria and fungal phytopathogens. Ethyl acetate extract of S. levis strain HFM-2 was purified using silica-gel column chromatography and reverse-phase high-performance liquid chromatography. Structure elucidation of the purified antimicrobial compound was done by performing detailed analyses including MS, IR, and NMR. The bacteriostatic activity of the compound revealed interesting values against broad-spectrum MDR pathogens. The bacterial cell destruction was recorded through SEM and fluorescence microscopy analyses. HFM-2P is displayed to be non-mutagenic and non-cytotoxic to the normal cell line. However, dose-dependent cytotoxicity was observed against the HeLa cancer cell line and exhibited antimutagenic activity against Salmonella Typhimurium strains (TA98 and TA100). This study is the first to report antiproliferative, DNA protective potential, antimutagenic properties, and antimicrobial activity of a 2,6-disubstituted chromone derivative isolated from S. levis strain HFM-2 against drug-resistant MRSA, VRE, and fungal phytopathogens. Therefore, this essential compound could be a candidate for future research in the pharmaceutical and agricultural sectors.

Siti Alfiatul Amani, Dodyk Pranowo, Susinggih Wijana

Pokak is a variant of the Madurese ginger drink made from spices. The main ingredient is ginger, while other additional ingredients are cloves, cinnamon, nutmeg, and masohi/masoyi wood. In general, these drinks are sold in liquid form. The maceration method was used to obtain pokak extract while spray dryer was used to obtain Pokak powder. Pokak is believed to boost immunity, increase stamina and warm the body. The development of Pokak Madura in powder form can increase the sale value, be more practical in the making and have a longer shelf life. This study aims to determine the optimal composition and conditions of Pokak microencapsulation. The parameters used are maltodextrin concentration (4.05; 5; 10; 15; 15.94%) and inlet temperature (120.27; 125; 150; 175; 179.7 oC). The optimization method used to get the best pokak powder was RSM (Response Surface Methodology). Tests at this stage were the total flavonoid test, antioxidant test, and morphology or best pokak powder profile using SEM (Scanning Electron Microscopy). Optimization results for the best treatment were a maltodextrin concentration of 10.639% and an inlet temperature of 148.042 oC resulting in a total of 6.447 mg QE/gram flavonoids and a percentage of antioxidants of 13.078%. The morphology of the particles is wrinkled with an average particle size of 5.372 µm. Thus maltodextrin as a coating or coating material with DE 10-12 cannot form spherical-shaped powder particles.

Danling Liao, Shijia Wei, Jianzhang Hu

Abstract Background Autophagy has recently been shown to be critical for protecting peripheral nerve regeneration. This study explored the impact of miR-542-3p on diabetic corneal nerve regeneration and epithelial healing through the regulation of autophagy. Methods A type 1 diabetes model was established in male mice through streptozotocin administration. Immunofluorescence staining of β-Tubulin III and sodium fluorescein staining were performed to observe corneal nerve fiber density and corneal epithelial healing, respectively. Western blotting, immunofluorescence and transmission electron microscopy were used to determine autophagy levels. Subconjunctival injection of RAPA and 3-MA altered autophagy levels; with them, we evaluated the role of autophagy in diabetic keratopathy. miRNA sequencing and bioinformatics analysis were performed to identify miRNA-mRNA networks with potential autophagy-regulating roles, and miR-542-3p was measured by quantitative real-time polymerase chain reaction (qRT-PCR). miR-542-3p antagomir was injected subconjunctivally to assess the role in diabetic corneal neuropathy. Results Our data suggest that autophagy is suppressed in the diabetic corneal nerve and that activation of autophagy promotes diabetic corneal wound healing. We identified a potential autophagy-regulating miRNA-mRNA network in the diabetic trigeminal ganglion, in which miR-542-3p expression was significantly upregulated. Inhibition of miR-542-3p significantly enhanced the level of autophagy in trigeminal ganglion by upregulating ATG4D expression, thereby accelerating diabetic corneal nerve regeneration and epithelial healing. Conclusions Dysregulated autophagy is an important contributor to delayed diabetic corneal injury healing. Inhibiting miR-542-3p promotes diabetic corneal nerve regeneration and epithelial healing through autophagy activation by ATG4D.

S. Marchini, S. Günther, J. Wintterlin

Takahiro Ikeda, G. Popescu, R. Dasari et al.

T. Taubner, D. Korobkin, Y. Urzhumov et al.

R. Ober, R. Ober, S. Ram et al.

Stefan Wilhelm

J. Heymann, D. Belnap, D. Belnap

Nancy Nisticò, Annamaria Aloisio, Antonio Lupia et al.

Triple-negative breast cancer (TNBC) is an aggressive malignancy characterized by the lack of expression of estrogen and progesterone receptors and amplification of human epidermal growth factor receptor 2 (HER2). Being the Epidermal Growth Factor Receptor (EGFR) highly expressed in mesenchymal TNBC and correlated with aggressive growth behavior, it represents an ideal target for anticancer drugs. Here, we have applied the phage display for selecting two highly specific peptide ligands for targeting the EGFR overexpressed in MDA-MB-231 cells, a human TNBC cell line. Molecular docking predicted the peptide-binding affinities and sites in the extracellular domain of EGFR. The binding of the FITC-conjugated peptides to human and murine TNBC cells was validated by flow cytometry. Confocal microscopy confirmed the peptide binding specificity to EGFR-positive MDA-MB-231 tumor xenograft tissues and their co-localization with the membrane EGFR. Further, the peptide stimulation did not affect the cell cycle of TNBC cells, which is of interest for their utility for tumor targeting. Our data indicate that these novel peptides are highly specific ligands for the EGFR overexpressed in TNBC cells, and thus they could be used in conjugation with nanoparticles for tumor-targeted delivery of anticancer drugs.

Chao Li, Christoph Kaspar, Ping Zhou et al.

Abstract Electron-vibration coupling is of critical importance for the development of molecular electronics, spintronics, and quantum technologies, as it affects transport properties and spin dynamics. The control over charge-state transitions and subsequent molecular vibrations using scanning tunneling microscopy typically requires the use of a decoupling layer. Here we show the vibronic excitations of tetrabromotetraazapyrene (TBTAP) molecules directly adsorbed on Ag(111) into an orientational glassy phase. The electron-deficient TBTAP is singly-occupied by an electron donated from the substrate, resulting in a spin 1/2 state, which is confirmed by a Kondo resonance. The TBTAP•− discharge is controlled by tip-gating and leads to a series of peaks in scanning tunneling spectroscopy. These occurrences are explained by combining a double-barrier tunneling junction with a Franck-Condon model including molecular vibrational modes. This work demonstrates that suitable precursor design enables gate-dependent vibrational excitations of molecules on a metal, thereby providing a method to investigate electron-vibration coupling in molecular assemblies without a decoupling layer.

Gertrudis R. Meñe, Maxmillian G. Mpina, Alejandro Lopelo et al.

Introduction: Malaria and soil-transmitted helminth (STH) co-infection is an important parasitic infection affecting populations in co-endemic countries including Equatorial Guinea. To date, the health impact of STH and malaria co-infection is inconclusive. The current study aimed to report the malaria and STH infection epidemiology in the continental region of Equatorial Guinea. Methods: We performed a cross-sectional study between October 2020 and January 2021 in the Bata district of Equatorial Guinea. Participants aged 1–9 years, 10–17 years and above 18 were recruited. Fresh venous blood was collected for malaria testing via mRDTs and light microscopy. Stool specimens were collected, and the Kato–Katz technique was used to detect the presence of <i>Ascaris lumbricoides</i>, <i>Trichuris trichiura</i>, <i>hookworm</i> spp. and intestinal Schistosoma eggs. Results: A total of 402 participants were included in this study. An amount of 44.3% of them lived in urban areas, and only 51.9% of them reported having bed nets. Malaria infections were detected in 34.8% of the participants, while 50% of malaria infections were reported in children aged 10–17 years. Females had a lower prevalence of malaria (28.8%) compared with males (41.7%). Children of 1–9 years carried more gametocytes compared with other age groups. An amount of 49.3% of the participants infected with <i>T. trichiura</i> had malaria parasites compared with those infected with <i>A. lumbricoides</i> (39.6%) or both (46.8%). Conclusions: The overlapping problem of STH and malaria is neglected in Bata. The current study forces the government and other stakeholders involved in the fight against malaria and STH to consider a combined control program strategy for both parasitic infections in Equatorial Guinea.

Anna-Clara Ivarsson, Elin Fransén, Ioanna Broumou et al.

Abstract Background Light microscopy and rapid diagnostic tests (RDT) have long been the recommended diagnostic methods for malaria. However, in recent years, loop-mediated isothermal amplification (LAMP) techniques have been shown to offer superior performance, in particular concerning low-grade parasitaemia, by delivering higher sensitivity and specificity with low laboratory capacity requirements in little more than an hour. In this study, the diagnostic performance of two LAMP kits were assessed head-to-head, compared to highly sensitive quantitative real time PCR (qPCR), in a non-endemic setting. Methods In this retrospective validation study two LAMP kits; Alethia® Illumigene Malaria kit and HumaTurb Loopamp™ Malaria Pan Detection (PDT) kit, were evaluated head-to-head for detection of Plasmodium-DNA in 133 biobanked blood samples from suspected malaria cases at the Clinical Microbiology Laboratory of Region Skåne, Sweden to determine their diagnostic performance compared to qPCR. Results Of the 133 samples tested, qPCR detected Plasmodium DNA in 41 samples (defined as true positives), and the two LAMP methods detected 41 and 37 of those, respectively. The results from the HumaTurb Loopamp™ Malaria PDT kit were in complete congruence with the qPCR, with a sensitivity of 100% (95% CI 91.40–100%) and specificity of 100% (95% CI 96.07–100%). The Alethia® Illumigene Malaria kit had a sensitivity of 90.24% (95% CI 76.87–97.28) and a specificity of 95.65% (95% CI 89.24–98.80) as compared to qPCR. Conclusions This head-to-head comparison showed higher performance indicators of the HumaTurb Loopamp™ Malaria PDT kit compared to the Alethia® illumigene Malaria kit for detection of malaria.