A near-infrared fluorescent probe for imaging peroxynitrite levels in paw edema mice and drug evaluation.

A near-infrared fluorescent probe (TX-P) for detecting peroxynitrite is constructed. The probe has a near-infrared emission (725 nm), large Stokes shift (125 nm) and excellent sensitivity and selectivity. In addition, TX-P can be used to visualize ONOO- in living cells, image ONOO- in paw edema mice and evaluate anti-inflammatory drugs.

Near-infrared fluorescent probe for the imaging of viscosity in fatty liver mice and valuation of drug efficacy.

Fatty liver disease affects at least 25 percent of the population worldwide and is a severe metabolic syndrome. Viscosity is closely related to fatty liver disease, so it is urgent to develop an effective tool for monitoring viscosity. Herein, a NIR fluorescent probe called MBC-V is developed for imaging viscosity, consisting of dimethylaniline and malonitrile-benzopyran. MBC-V is non-fluorescent in low viscosity solutions due to intramolecular rotation. In high viscosity solution, the intramolecular rotation of MBC-V is suppressed and the fluorescence is triggered. MBC-V has long emission wavelength at 720 nm and large Stokes shift about 160 nm. Moreover, MBC-V can detect changes in cell viscosity in fatty liver cells, and can image the therapeutic effects of drug in fatty liver cells. By taking advantage of NIR emission, MBC-V can be used as an imaging tool for fatty liver disease and a way to evaluate the therapeutic effect of drug for fatty liver disease.

Bridging dose of U-100 glargine with first dose of insulin degludec improves glycaemia in the 48 h after transition in twice-daily glargine users.

AIMS: To study the effects of a bridging dose of U-100 glargine (U-100G) with the first dose of degludec in type 1 diabetes (T1D) patients transitioning from glargine to degludec, by comparing the glucose metrics 48 h before and after the transition. MATERIALS AND METHODS: Patients with T1D on a stable U-100G regimen and with glycated haemoglobin concentration <75 mmol/mol were randomized (double-blind) to one dose of placebo or U-100G with first dose of degludec, administered at 9:00 pm. Patients on once-daily U-100G at baseline received 50% of total U-100G dose (bridging dose), while patients on twice-daily U-100G received 50% of the evening U-100G dose. Participants wore a continuous glucose monitor during the study. RESULTS: Forty participants were randomized, of whom 37 completed the study. The cohort was 65% male, the mean age was 47 years, duration of T1D 22 years, BMI 26 kg/m2, HbA1c 51 mmol/mol and total daily insulin dose 0.7 units/kg body weight. The bridging group included 19 participants (once-daily U-100G: n = 12; twice-daily U-100G: n = 7) and the placebo group included 18 participants (once-daily U-100G: n = 12; twice-daily U-100G: n = 6). Change in time in range (TIR) was not significantly different between the two treatment groups. In secondary analyses, among twice-daily U-100G users, TIR (3.9-10 mmol/L) increased 8% in the bridging group in the 48 h after first dose of degludec compared to the preceding 48 h, while participants in the placebo group had a 9.5% decrease (p = 0.027). CONCLUSIONS: A subgroup of well-controlled twice-daily U-100G users transitioning to degludec benefited from a 50% bridging dose of evening U-100G with the first dose of degludec in a small pilot study.

Differential Association between Blood Glucose Levels and Nonrelapse Mortality after Allogeneic Hematopoietic Cell Transplantation Based on Presence or Absence of Preexisting Diabetes.

Malglycemia, defined as hyperglycemia, hypoglycemia, or increased glycemic variability, has been associated with increased mortality after allogeneic hematopoietic cell transplantation (HCT). Among critically ill non-HCT recipients with diabetes and poor glycemic control, compared to those without diabetes, stringent blood glucose control has been associated with increased mortality. This study investigated whether a pre-HCT diagnosis of diabetes and the type of pre-HCT diabetes treatment modulate the previously reported negative impact of malglycemia on post-HCT nonrelapse mortality (NRM). We performed a single-institution retrospective analysis of mortality outcomes after allogeneic HCT as a function of post-HCT blood glucose levels, pre-HCT diagnosis of diabetes, and type of pre-HCT diabetes treatment (insulin, no insulin). A total of 1062 patients who underwent allogeneic HCT between 2015 and 2020 were included in this study. Among these patients, 84 (8%) had a pre-HCT diagnosis of diabetes, of whom 38 (4%) used insulin and 46 (4%) used a noninsulin antiglycemic agent. Post-HCT blood glucose values measured within 100 days from HCT, modeled as a continuous nonlinear time-varying covariate, were associated with day-200 NRM, with both lower and higher glycemic values associated with higher NRM compared to normoglycemic values (adjusted P < .0001). The association between post-HCT blood glucose and NRM varied, however, depending on the presence or absence of a pre-HCT diagnosis of diabetes; that is, there was evidence of a statistical interaction between blood glucose levels and diabetes (adjusted P = .008). In particular, the detrimental impact of hyperglycemic values was more pronounced in patients without a pre-HCT diagnosis of diabetes compared to those with a pre-HCT diagnosis of diabetes. As reported previously, higher and lower blood glucose levels measured within 100 days after allogeneic HCT were associated with an increased risk of NRM; however, this association was more pronounced among patients without a pre-HCT diagnosis of diabetes compared to those with a pre-HCT diagnosis of diabetes, suggesting that patients with diabetes are relatively protected from the downstream effects of hyperglycemia. These data support the notion that patients with pre-HCT diabetes may need a different approach to blood glucose management after transplantation compared to those without diabetes. © 2024 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

A near-infrared fluorescent probe for viscosity: Differentiating cancer cells from normal cells and dual-modal imaging in tumor mice.

As a basic parameter of the intracellular microenvironment, viscosity is closely related to the development of cancer. Thus, it is necessary to utilize a sensitive tool to visualize the viscosity in tumor cells and mice, which is helpful for the diagnosis of cancer. Herein, a novel dual-modal probe (IX-V) that has a near-infrared fluorescence (NIRF) and photoacoustic (PA) response to viscosity is synthesized. In low viscosity media, the probe has no fluorescence. With the increase of viscosity, the fluorescence is produced in the near-infrared region due to the inhibition of the TICT process. At the same time, the probe shows different photoacoustic (PA) signals in different viscosity media. Most notably, the viscosity in tumor cells has been imaged successfully by the application of IX-V, and the probe can effectively distinguish cancer cells from normal cells co-cultured in one dish by the difference of fluorescence intensity. In addition, the probe has been used for dual-modal imaging (NIRF and PA) of viscosity in tumor mice, which provides a tool for exploring the relationship between viscosity and diseases. That is to say, IX-V can achieve complementary imaging effects and has great application prospects in the tumor diagnosis.

Long-Term Imaging of Cys in Cells and Tumor Mice by a Solid-State Fluorescence Probe.

Cysteine is an important biological thiol and is closely related to cancer. It remains a challenge to develop a probe that can provide long-term fluorescence detection and imaging of Cys in cells as well as in living organisms. Here, a solid-state fluorophore HTPQ is combined with an acrylate group to construct a solid-state fluorescent probe HTPQC for Cys recognition. The fluorescence of the probe is quenched when the photoinduced electron transfer (PET) process is turned on and the excited-state intramolecular proton transfer (ESIPT) process is turned off. In the presence of Cys, an obvious solid-state fluorescence signal can be observed. The double quenching mechanism makes the probe HTPQC have the advantages of high sensitivity, good selectivity, and high contrast of biological imaging. Due to low cytotoxicity, the probe HTPQC can be used to detect exogenous and endogenous Cys in living cells and is capable of imaging over long periods of time. By making full use of long wavelengths, the probe can be applied for the detection of Cys levels in tumor mice and equipped with the ability to conduct long-term imaging in vivo.

Dual Key-Activated Nir-I/II Fluorescence Probe for Monitoring Photodynamic and Photothermal Synergistic Therapy Efficacy.

As cancer markers, hydrogen peroxide (H2 O2 ) and viscosity play an essential role in the development of tumors. Meanwhile, based on the performance of near-infrared (NIR) fluorescence imaging and the high efficiency of photodynamic therapy (PDT) and photothermal therapy (PTT) synergistic therapy, it is urgent to develop a dual-key (H2 O2 and viscosity) activated fluorescence probe for cancer phototherapy. Herein, a NIR-I/II fluorescence probe named BX-B is reported. In the presence of both H2 O2 and viscosity, the fluorescence signal of NIR-I (810 nm) and NIR-II (945 nm) can be released. In the presence of H2 O2 , the PDT and PTT effects are observed. BX-B is used to monitor its therapeutic effects in cancer cells and tumor-bearing mice due to the increased viscosity caused by PDT and PTT. In addition, the tumors of mice treated with BX-B are almost completely ablated after the laser irradiation based on its PDT and PTT synergistic therapy. This work provides a reliable platform for effective cancer treatment and immediate evaluation of therapeutic effects.

Tumor-Targeting Probe for Dual-Modal Imaging of Cysteine In Vivo.

Cysteine (Cys) is a crucial biological thiol that has a vital function in preserving redox homeostasis in organisms. Studies have shown that Cys is closely related to the development of cancer. Thus, it is necessary to design an efficient method to detect Cys for an effective cancer diagnosis. In this work, a novel tumor-targeting probe (Bio-Cy-S) for dual-modal (NIR fluorescence and photoacoustic) Cys detection is designed. The probe exhibits high selectivity and sensitivity toward Cys. After reaction with Cys, both NIR fluorescence and photoacoustic signals are activated. Bio-Cy-S has been applied for the dual-modal detection of Cys levels in living cells, and it can be used to distinguish normal cells from cancer cells by different Cys levels. In addition, the probe is capable of facilitating dual-modal imaging for monitoring changes in Cys levels in tumor-bearing mice. More importantly, the excellent tumor-targeting ability of the probe greatly improves the signal-to-noise ratio of imaging. To the best of our knowledge, this is the first Cys probe to combine targeting and dual-modal imaging performance for cancer diagnosis.

A novel near-infrared fluorescent probe for the imaging of viscosity in cells and tumor-bearing mice.

A near-infrared fluorescent probe (IC-V) for detecting viscosity is constructed. The probe has a large Stokes shift (170 nm) and an about 180-fold increase in fluorescence intensity at 700 nm. In addition, IC-V can not only distinguish cancer cells from normal cells, but also monitor viscosity in normal mice and tumor-bearing mice.

Prognosis after hepatic resection of patients with hepatocellular carcinoma related to non-alcoholic fatty liver disease: meta-analysis.

BACKGROUND: Whether the safety and efficacy of hepatic resection differ between patients whose hepatocellular carcinoma (HCC) is related to non-alcoholic fatty liver disease (NAFLD) or has other aetiologies is unknown. A systematic review was performed to explore potential differences between such conditions. METHODS: PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched for relevant studies that reported hazard ratios (HRs) for overall and recurrence-free survival between patients with NAFLD-related HCC or HCC of other aetiologies. RESULTS: The meta-analysis involved 17 retrospective studies involving 2470 patients (21.5 per cent) with NAFLD-related HCC and 9007 (78.5 per cent) with HCC of other aetiologies. Patients with NAFLD-related HCC were older and had higher body mass index (BMI), but were less likely to have cirrhosis (50.4 per cent versus 64.0 per cent, P < 0.001). The two groups suffered similar rates of perioperative complications and mortality. Patients with NAFLD-related HCC had slightly higher overall survival (HR 0.87, 95 per cent c.i. 0.75 to 1.02) and recurrence-free survival (HR 0.93, 95 per cent c.i. 0.84 to 1.02) than those with HCC of other aetiologies. In the various subgroup analyses, the only significant finding was that Asian patients with NAFLD-related HCC had significantly better overall survival (HR 0.82, 95 per cent c.i. 0.71 to 0.95) and recurrence-free survival (HR 0.88, 95 per cent c.i. 0.79 to 0.98) than Asian patients with HCC of other aetiologies. CONCLUSION: The available evidence suggests that patients with NAFLD-related HCC have similar perioperative complications and mortality, but potentially longer overall and recurrence-free survival, compared with those with HCC of other aetiologies. Tailored surveillance strategies should be developed for patients with NAFLD without cirrhosis.

A near-infrared fluorescent probe for monitoring abnormal mitochondrial viscosity in cancer and fatty-liver mice model.

Viscosity is an important component of cell microenvironment, and abnormal mitochondrial viscosity is associated with many diseases such as tumor and fatty liver. Herein, a near-infrared fluorescence probe (QX-V) based on quinoline-xanthene dye for detecting viscosity is constructed. In high viscosity medium, the free rotation of single bond is inhibited and the fluorescence is released. The probe shows high sensitivity together with good selectivity. Notably, QX-V has a long excitation wavelength (710 nm) and emission wavelength (786 nm). At the same time, the probe is a positively charged molecule that can target mitochondria. QX-V can not only distinguish cancer cells from normal cells, but also make a distinction between normal cells and fatty hepatocytes. In addition, QX-V is used to image viscosity abnormality in tumor-bearing mice. The probe also has a good ability to image viscosity abnormality caused by liver injury in fatty-liver mice.

Role of hydrogen sulphide in physiological and pathological angiogenesis.

The role of hydrogen sulphide (H2 S) in angiogenesis has been widely demonstrated. Vascular endothelial growth factor (VEGF) plays an important role in H2 S-induced angiogenesis. H2 S promotes angiogenesis by upregulating VEGF via pro-angiogenic signal transduction. The involved signalling pathways include the mitogen-activated protein kinase pathway, phosphoinositide-3 kinase pathway, nitric oxide (NO) synthase/NO pathway, signal transducer and activator of transcription 3 (STAT3) pathway, and adenosine triphosphate (ATP)-sensitive potassium (KATP ) channels. H2 S has been shown to contribute to tumour angiogenesis, diabetic wound healing, angiogenesis in cardiac and cerebral ischaemic tissues, and physiological angiogenesis during the menstrual cycle and pregnancy. Furthermore, H2 S can exert an anti-angiogenic effect by inactivating Wnt/ß-catenin signalling or blocking the STAT3 pathway in tumours. Therefore, H2 S plays a double-edged sword role in the process of angiogenesis. The regulation of H2 S production is a promising therapeutic approach for angiogenesis-associated diseases. Novel H2 S donors and/or inhibitors can be developed in the treatment of angiogenesis-dependent diseases.

Dipole Effect of BN-Doped Tetrathienonaphthalene on Photo-Physical Properties and Lewis Acidity of the D-π-A Derivatives.

Dimesitylboryl-acceptor (A) and diarylamine-donor (D) substituents are introduced at α positions of BN-doped tetrathienonaphthalene in the same and opposite directions of the B-N bond, namely, B-BN-N and N-BN-B, in order to demonstrate how the substitution patterns influence the photophysical properties. The photophysical and electrochemical properties of these D-π-A molecules have been investigated in detail, aided by UV-vis absorption and fluorescence spectroscopy as well as cyclic voltammetry. We find that both B-BN-N and N-BN-B show the typical intramolecular charge transfer emission. N-BN-B exhibits strong fluorescence with a narrower band gap and stronger Lewis acidity than that of B-BN-N. DFT calculations help give a reasonable explanation that subtle differences in the electronic structure of the host skeleton could also influence the substituents and feed back this effect to the entire molecule.

Endophytic bacterial and fungal community compositions in different organs of ginseng (Panax ginseng).

Panax ginseng (Panax ginseng C. A. Mey.) is a perennial herb of the genus ginseng, which is used as medicine with dried roots and rhizomes. With the deepening of research on ginseng, the chemical components and pharmacological effects of ginseng have gradually been discovered. Endophytes are beneficial to host plants. However, the composition of endophytes in different organs from ginseng is poorly elucidated. The report of ginsenoside production by endophytic microbes isolated from Panax sp., motivated us to explore the endophytic microbial diversity related to the roots, stems, and leaves. In this study, the V5-V7 variable region of endophytic bacteria 16S rRNA gene and V1 variable region of endophytic fungi ITS gene in different organs were analyzed by high-throughput sequencing. The diversity and abundance of endophytic microbes in the three organs are different and are affected by the organs. For example, the most abundant endophytic bacterial genus in roots was Mycobacterium, while, the stems and leaves were Ochrobactrum. Similarly, the fungal endophytes, Coniothyrium and Cladosporium, were also found in high abundance in stems, in comparison to roots and leaves. The Shannon index shows that the diversity of endophytic bacteria in roots is the highest, and the richness of endophytic bacterial was root > stem (p < 0.05). Principal coordinate analysis showed that there were obvious microbial differences among the three groups, and the endophytic bacterial composition of the leaves was closer to that of the roots. This study provides an important reference for the study of endophytic microorganisms in ginseng.

Camrelizumab, apatinib, nab-paclitaxel, and S-1 in combination for the conversion therapy of advanced gastric cancer / 国际外科学杂志

Objective:To assess the efficacy and safety of the combination therapy of camrelizumab, apatinib, nab-paclitaxel, and S-1 for patients with locally unresectable advanced gastric cancer.Methods:From September 1, 2019 to August 1, 2021, in Beijing Friendship Hospital Affiliated to Capital Medical University, 17 patients with advanced gastric cancer were enrolled in this prospective, single-arm study. All the enrolled patients received camrelizumab, nab-paclitaxel, apatinib and S-1 combination therapy (in each 21 days cycle, camrelizumab 200 mg intravenously, D1; nab-paclitaxel 240 mg/m 2 intravenously, D2; apatinib 500 mg orally, once a day, D1-D21; S-1 40-60 mg twice a day, D1-D14). Patients who have been evaluated by multidisciplinary team to be eligible for radical surgery should stop treatment for at least 2 weeks. Patients were discontinued from the study when disease progression or unbearable toxicity, or withdrew consent. We analyzed the conversion rate, objective response rate (ORR), disease control rate (DCR), overall survival (OS) and safety.Statistical data were show by numbers and persentages(%), and comparisons between subgroups were assessed by Fisher′s exact probability method. Patients survival was analyzed using Kaplan-Meier curves and compared between groups using Log-rank. Results:At the data of cutoff (December 15, 2021), the median follow-up duration was 19.6 months. Eight of 17 patients underwent gastrectomy, and all of them were R0 resection (47.1%, 95% CI: 0.262-0.690). ORR was 47.1%, DCR was 82.4%, the median overall survival was 23.63 months. Grade 3 and 4 adverse events occurred in 3 patients (17.6%), including neutropenia, thrombocytopenia, anemia and upper gastrointestinal hemorrhage. There were no serious treatment-related adverse events or treatment-related deaths. Conclusion:In this trial, the combination of camrelizumab, apatinib, nab-paclitaxel and S-1 as the conversion therapy showed significant anti-tumor activity and manageable adverse events, providing a new option for locally unresectable advanced gastric cancer.

Antibiotic pollution promotes dominance by harmful cyanobacteria: A case study examining norfloxacin exposure in competition experiments.

Cyanobacterial harmful algal blooms (cyanoHABs) in freshwater lakes across the globe are often combined with other stressors. Pharmaceutical pollution, especially antibiotics in water bodies, poses a potential hazard in aquatic ecosystems. However, how antibiotics influence the risk of cyanoHABs remains unclear. Here, we investigated the effects of norfloxacin (NOR), one of the most widely used antibiotics globally, to a bloom-forming cyanobacterium (Microcystis aeruginosa) and a common green alga (Scenedesmus quadricauda), under both mono- and coculture conditions. Taxon-specific responses to NOR were evaluated in monoculture. In addition, the growth rate and change in ratio of cyanobacteria to green algae when cocultured with exposure to NOR were determined. In monocultures of Microcystis, exposure to low concentrations of NOR resulted in decreases in biomass, chlorophyll a and soluble protein content, while superoxide anion content and superoxide dismutase activity increased. However, NOR at high concentration only slightly affected Scenedesmus. During the co-culture trials of Microcystis and Scenedesmus, the 5 µg · L-1 NOR treatment increased the ratio of Microcystis to co-cultured Scenedesmus by 47.2%. Meanwhile, although Scenedesmus growth was enhanced by 4.2% under NOR treatment in monoculture, it was conversely inhibited by 63.4% and 38.2% when co-cultured with Microcystis with and without NOR, respectively. Our results indicate that antibiotic pollution has a potential risk to enhance the perniciousness of cyanoHABs by disturbing interspecific interaction between cyanobacteria and green algae. These results reinforce the need for scientists and managers to consider the influence of xenobiotics in shaping the outcome of interactions among multiple species in aquatic ecosystems.

Millisecond Time-scale Photoluminescence of B-N-doped Tetrathienonaphthalene with Borane/Amine Substituents.

BN-doped polycyclic aromatic hydrocarbons (PAHs) have attracted numerous attentions because of their fascinating optical and electronic properties. In this work, a series of electron-donor (amine)- and -acceptor (borane)-functionalized BN-doped polycyclic aromatic hydrocarbons were prepared to study the substituents' effect on the photophysical properties. As a result, the compound with both donor and acceptor, BN, exhibits both local emission (LE) and charge-transfer emission (CT) in polar solvents. Especially, the CT emission with a longer wavelength revealed a lifetime as long as millisecond time scale at room temperature, indicating typical phosphorescence characteristics. Low-temperature photoluminescent (PL) spectroscopy and a theoretical study were conducted to help to interpret this phenomenon, and it turned out to be the lowering of the S1 energy level of BN which makes the intersystem crossing favorable. Furthermore, fluoride anion titration experiments exhibit the application potential of the dual-emission phenomenon of BN for ratiometric sensory materials.

Effect of Systematic Exercise Rehabilitation on Patients With Knee Osteoarthritis: A Randomized Controlled Trial.

OBJECTIVES: We aimed to compare the outcomes of exercise rehabilitation and conventional treatment in patients with knee osteoarthritis. METHODS: This trial included a total of 166 patients diagnosed with knee osteoarthritis; they were randomly divided into groups. The experimental group underwent systematic exercise rehabilitation, while the control group received naproxen (n = 28), diclofenac (n = 27), or celecoxib (n = 19). Improvement in symptoms, knee function, and quality of life were compared. SPSS Statistics 24.0 was used for the data analysis. RESULTS: The mean age of patients was 56.0 ± 10.5 years, and the average follow-up time was 12 ± 2.3 weeks. No statistically significant differences were seen in age, body mass index, and sex (P > 0.05) between the groups. The average Western Ontario and MacMaster Universities (WOMAC) scores after treatment were 84.4 ± 15.2, 108.3 ± 3.9, 107.4 ± 5.4, and 107 ± 6.0 in the exercise rehabilitation, diclofenac, naproxen, and celecoxib groups, respectively. The mean Lysholm scores were 60.3 ± 14.9, 41.0 ± 0.1, 43.5 ± 5.3, and 41.7 ± 3.6 in the exercise rehabilitation, diclofenac, naproxen, and celecoxib groups, respectively. The mean SF-36 (Short Form-36 Survey) scores were 105.4 ± 21.5, 82.5 ± 3.7, 84.2 ± 3.5, and 83.7 ± 5.0 in the exercise rehabilitation, naproxen, celecoxib, and diclofenac groups, respectively. The average ranges of knee motion were 125.0 ± 6.2°, 116.4 ± 1.4°, 114.7 ± 1.1°, and 115.7 ± 0.8° after exercise rehabilitation, diclofenac, naproxen, and celecoxib treatments, respectively. These data presented statistical differences between the groups. CONCLUSION: Exercise better improved symptoms and quality of life in patients with knee osteoarthritis over a 12-week follow-up period than that achieved with nonsteroidal anti-inflammatory drugs and COX-2 inhibitors.

Research progress of immune checkpoint inhibitors in advanced biliary tract cancers / 国际外科学杂志

Biliary tract cancer (BTC) is a series of rare malignancies with poor overall prognosis. Radical surgery the preferred treatment option, but most patients have lost the opportunity of surgery at the time of diagnosis. At present, there are limited systematical treatment options for biliary tract cancers, and such treatments have poor efficacy and short duration of responses. In the past few years, immune checkpoint inhibitor therapy has been established as an effective systemic therapy option for many solid tumors and hematological tumors. The research for biliary tract cancer treated by of immune checkpoint inhibitors has been continuously carried out and demonstrated the anti-tumor efficacy and safety. However, in view of the low incidence and high heterogeneity of BTC more large number of clinical trials and practices need to be carried out, and the effective combination regimens and predictive biomarkers are urgent to be explored. This article reviews the recent clinical studies on immune checkpoint inhibitors for biliary tract cancer, and summarizes the ongoing clinical studies. At the same time, the predictive biomarkers of immune checkpoint inhibitors proposed by domestic and foreign researches in recent years are summarized.

Micro-computed tomography evaluation of root canal filling quality with apical negative pressure.

OBJECTIVES: The objective of the present study was to compare, using micro-computed tomography (micro-CT), the location and volume percentage of voids in root canals that were obturated with a premixed tricalcium silicate sealer and a single gutta-percha master cone, in the presence or absence of apical negative pressure. METHODS: Twenty extracted human mandibular premolars were cleaned and shaped. The teeth were assigned to 2 groups (n = 10) according to the filling technique: apical negative pressure sealer application combined with the single-cone technique (NPS) or syringe-assisted sealer application combined with the single-cone technique (SS). Each specimen was scanned using micro-CT at 10 µm resolution. The percentages of voids were calculated from segmental regions of interest. Data were analysed using nonparametric statistical methods, with statistical significance pre-set at α = 0.05. RESULTS: Significant difference was identified (p < 0.05) in the overall percentage of voids between the NPS group (0.33 %; interquartile range 0.25 %) and the SS group (6.29 %; interquartile range 5.57 %). In the NPS group, the percentages of voids in the coronal-third or middle-third of the canal space were statistically lower than that in apical-third (p < 0.0167, Bonferroni adjustment), with no significant difference between the former two groups. In the SS group, no significant difference in the percentages of voids was identified among the coronal-third, middle-third and apical-third of the canal space. CONCLUSIONS: Apical negative pressure sealer application combined with the single-cone technique produces fewer voids in root canal fillings than the conventional single-cone technique. CLINICAL SIGNIFICANCE: The apical negative pressure sealer application technique combined with single-cone filling constitutes a novel root canal obturation technique that improves the quality of root canal filling by minimising the volume of voids within the three-dimensional canal space.