BOTRYOID POLLEN 1 regulates ROS-triggered PCD and pollen wall development by controlling UDP-sugar homeostasis in rice.

Uridine diphosphate (UDP)-sugars are important metabolites involved in the biosynthesis of polysaccharides and may be important signaling molecules. UDP-glucose 4-epimerase (UGE) catalyzes the interconversion between UDP-Glc and UDP-Gal, whose biological function in rice (Oryza sativa) fertility is poorly understood. Here, we identify and characterize the botryoid pollen 1 (bp1) mutant and show that BP1 encodes a UGE that regulates UDP-sugar homeostasis, thereby controlling the development of rice anthers. The loss of BP1 function led to massive accumulation of UDP-Glc and imbalance of other UDP-sugars. We determined that the higher levels of UDP-Glc and its derivatives in bp1 may induce the expression of NADPH oxidase genes, resulting in a premature accumulation of reactive oxygen species (ROS), thereby advancing programmed cell death (PCD) of anther walls but delaying the end of tapetal degradation. The accumulation of UDP-Glc as metabolites resulted in an abnormal degradation of callose, producing an adhesive microspore. Furthermore, the UDP-sugar metabolism pathway is not only involved in the formation of intine but also in the formation of the initial framework for extine. Our results reveal how UDP-sugars regulate anther development and provide new clues for cellular ROS accumulation and PCD triggered by UDP-Glc as a signaling molecule.

The OsMYC2-JA feedback loop regulates diurnal flower-opening time via cell wall loosening in rice.

Diurnal flower-opening time (DFOT), the time of spikelet opening during the day, is an important trait for hybrid rice (Oryza sativa L.) seed production. Hybrids between indica and japonica rice varieties have strong heterosis, but the parental lines usually have different, nonoverlapping DFOTs. This reduces the success of hybrid seed production in crosses between indica and japonica subspecies, thus hindering the utilization of indica and japonica inter-subspecies heterosis. However, little is known about the molecular mechanisms regulating DFOT in rice. Here, we obtained japonica rice lines with a DFOT 1.5 h earlier than the wild type by overexpressing OsMYC2, a gene encoding a key transcription factor in the jasmonate (JA) signaling pathway. OsMYC2 is activated by JA signaling and directly regulates the transcription of genes related to JA biosynthesis and cell wall metabolism. Overexpressing OsMYC2 led to significantly increased JA contents and decreased cellulose and hemicellulose contents in lodicule cells, as well as the softening of lodicule cell walls. This may facilitate the swelling of lodicules, resulting in early diurnal flower-opening. These results suggest that the OsMYC2-JA feedback loop regulates DFOT in rice via cell wall remodeling. These findings shed light on the understanding of regulatory mechanism of the DFOT of plants, which should promote the development of indica and japonica varieties suitable for hybrid rice breeding.

Controlling diurnal flower-opening time by manipulating the jasmonate pathway accelerates development of indica-japonica hybrid rice breeding.

Inter-subspecific indica-japonica hybrid rice (Oryza sativa) has the potential for increased yields over traditional indica intra-subspecies hybrid rice, but limited yield of F1 hybrid seed production (FHSP) hinders the development of indica-japonica hybrid rice breeding. Diurnal flower-opening time (DFOT) divergence between indica and japonica rice has been a major contributing factor to this issue, but few DFOT genes have been cloned. Here, we found that manipulating the expression of jasmonate (JA) pathway genes can effectively modulate DFOT to improve the yield of FHSP in rice. Treating japonica cultivar Zhonghua 11 (ZH11) with methyl jasmonate (MeJA) substantially advanced DFOT. Furthermore, overexpressing the JA biosynthesis gene OPDA REDUCTASE 7 (OsOPR7) and knocking out the JA inactivation gene CHILLING TOLERANCE 1 (OsHAN1) in ZH11 advanced DFOT by 1- and 2-h respectively; and knockout of the JA signal suppressor genes JASMONATE ZIM-DOMAIN PROTEIN 7 (OsJAZ7) and OsJAZ9 resulted in 50-min and 1.5-h earlier DFOT respectively. The yields of FHSP using japonica male-sterile lines GAZS with manipulated JA pathway genes were significantly higher than that of GAZS wildtype. Transcriptome analysis, cytological observations, measurements of elastic modulus and determination of cell wall components indicated that the JA pathway could affect the loosening of the lodicule cell walls by regulating their composition through controlling sugar metabolism, which in turn influences DFOT. This research has vital implications for breeding japonica rice cultivars with early DFOT to facilitate indica-japonica hybrid rice breeding.

An E3 ubiquitin ligase CSIT2 controls critical sterility-inducing temperature of thermo-sensitive genic male sterile rice.

Thermo-sensitive genic male sterile (TGMS) lines are the core of two-line hybrid rice (Oryza sativa). However, elevated or unstable critical sterility-inducing temperatures (CSITs) of TGMS lines are bottlenecks that restrict the development of two-line hybrid rice. However, the genes and molecular mechanisms controlling CSIT remain unknown. Here, we report the CRITICAL STERILITY-INDUCING TEMPERATURE 2 (CSIT2) that encodes a really interesting new gene (RING) type E3 ligase, controlling the CSIT of thermo-sensitive male sterility 5 (tms5)-based TGMS lines through ribosome-associated protein quality control (RQC). CSIT2 binds to the large and small ribosomal subunits and ubiquitinates 80S ribosomes for dissociation, and may also ubiquitinate misfolded proteins for degradation. Mutation of CSIT2 inhibits the possible damage to ubiquitin system and protein translation, which allows more proteins such as catalases to accumulate for anther development and inhibits abnormal accumulation of reactive oxygen species (ROS) and premature programmed cell death (PCD) in anthers, partly rescuing male sterility and raised the CSIT of tms5-based TGMS lines. These findings reveal a mechanism controlling CSIT and provide a strategy for solving the elevated or unstable CSITs of tms5-based TGMS lines in two-line hybrid rice.

The Sword of Damocles: Microplastics and the molecular dynamics of sulfamonomethoxine revealed.

In recent years, the environmental impact of microplastics (MPs) and antibiotics (ATs) as pollutants cannot be ignored. In order to evaluate the carrier effect of MPs in the aqueous environment, three MPs, polyamide (PA), polyethylene (PE) and polyethylene terephthalate (PET), were selected in this study, and their structures were analyzed by means of characterization. A preliminary description of their interactions with sulfamonomethoxine was carried out by adsorption kinetics and isotherm fitting. The dominance of non-bonding capacity (van der Waals and electrostatic interaction forces) in the adsorption process was demonstrated using molecular dynamics (MD) simulations and density functional theory (DFT), with the interaction strengths ranked as PA > PE > PET, respectively. PA is less adsorbent stable at the molecular level but exhibits the largest adsorption capacity influenced by the characterized structure and multiple interaction forces. PET possesses a stronger stability and is not easily replaced by other substances. This will help to further understand the complex effect mechanism between MPs and organic pollutants, and provide an important reference for the prevention and control of environmental pollution.

Construction of a prediction model for pulmonary infection and its risk factors in Intensive Care Unit patients.

Objective: To identify independent risk factors of pulmonary infection in intensive care unit (ICU) patients, and to construct a prediction model. Methods: Medical data of 398 patients treated in the ICU of Jiaxing Hospital of Traditional Chinese Medicine from January 2019 to January 2023 were analyzed. Univariate and multivariate logistic regression analyses were used to identify independent risk factors for pulmonary infection in ICU patients. R software was used to construct a nomogram prediction model, and the prediction model was internally validated using computer simulation bootstrap method. Predictive value of the model was analyzed using the receiver operating characteristic (ROC) curve. Results: A total of 97 ICU patients (24.37%) developed pulmonary infection. Age, ICU stay time, invasive operation, diabetes, duration of mechanical ventilation, and state of consciousness were all identified as risk factors for pulmonary infection. The calibration curve of the constructed nomogram prediction model showed a good consistency between the predicted value of the model and the actual observed value. ROC curve analysis showed that the area under the curve (AUC) of the model was 0.784 (95% CI: 0.731-0.837), indicating a certain predictive value. Conclusions: Age, length of stay in ICU, invasive operation, diabetes, duration of mechanical ventilation, and state of consciousness are risk factors for pulmonary infection in ICU patients. The nomogram prediction model constructed based on the above risk factors has shown a good predictive value.

Tumor-associated macrophages as a potential therapeutic target in thyroid cancers.

Macrophages are important precursor cell types of the innate immune system and bridge adaptive immune responses through the antigen presentation system. Meanwhile, macrophages constitute substantial portion of the stromal cells in the tumor microenvironment (TME) (referred to as tumor-associated macrophages, or TAMs) and exhibit conflicting roles in the development, invasion, and metastasis of thyroid cancer (TC). Moreover, TAMs play a crucial role to the behavior of TC due to their high degree of infiltration and prognostic relevance. Generally, TAMs can be divided into two subgroups; M1-like TAMs are capable of directly kill tumor cells, and recruiting and activating other immune cells in the early stages of cancer. However, due to changes in the TME, M2-like TAMs gradually increase and promote tumor progression. This review aims to discuss the impact of TAMs on TC, including their role in tumor promotion, gene mutation, and other factors related to the polarization of TAMs. Finally, we will explore the M2-like TAM-centered therapeutic strategies, including chemotherapy, clinical trials, and combinatorial immunotherapy.

Parthenolide alleviates peritoneal fibrosis by inhibiting inflammation via the NF-κB/ TGF-ß/Smad signaling axis.

Peritoneal fibrosis is a common complication of peritoneal dialysis (PD) with a complicated pathogenesis and limited treatments. Parthenolide (PTL), a recognized nuclear factor-κB (NF-κB) inhibitor extracted from Tanacetum balsamita, has been widely used to treat various inflammatory diseases and has been proven to improve peritoneal fibrosis in PD mice by selectively inhibiting the phosphorylation of Smad2/3. Transforming growth factor-ß1 (TGF-ß1), via Smad-dependent signaling, has a pivotal role in promoting pathogenic of fibrosis. To investigate whether PTL can inhibit peritoneal fibrosis, we affected the interaction between NF-κB and the TGF-ß/Smad2/3 pathway. Long dwell peritoneal dialysis fluid (PDF) and peritoneum tissues were collected from continuous ambulatory peritoneal dialysis (CAPD) patients. PTL was administered intragastrically into a PD mouse model by daily infusion of 4.25% dextrose-containing PDF. Treated HMrSV5 cells or rat peritoneal mesothelial cells (RPMCs) were treated with high glucose(138 mM) at the same concentration as 2.5% dextrose-containing PDF and PTL. PD-related peritoneal fibrosis samples indicated an increase in inflammation, and PTL decreased the levels of inflammatory cytokines (L-6, TNF-α, and MCP-1). PTL inhibited high glucose-induced mesothelial-to-mesenchymal transition (MMT), as indicated by a reduced expression of fibrosis markers (fibronectin, collagen I, and α-SMA) and increased expression of the epithelial marker E-cadherin. PTL also significantly decreased TGF-ß1 expression and the phosphorylation of IκBα and NF-κBp65. The changes in the levels of TGF-ß1 expression and p-p65 or p65 showed similar trends according to western blot, immunohistochemistry, and immunofluorescence assays in vitro and in vivo. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were used to confirm that PTL regulates the transcription of TGF-ß1 induced by high glucose through NF-κBp65. In summary, PTL induces a therapeutic effect in peritoneal fibrosis by inhibiting inflammation via the NF-κB/ TGF-ß/Smad signaling axis.

The Protective Effect of Trichosanthes kirilowii Peel Polysaccharide on the Oxidative Damaged HepG2 and HUASMC Cells.

Background: Oxidative stress is an important cause of liver disease and atherosclerosis. Natural substances with antioxidant activity are good drugs for treating liver disease and atherosclerosis. Trichosanthes kirilowii Peel Polysaccharide (TKPP) can remove DPPH (2,2-Diphenyl-1-picrylhydrazyl) free radicals and hydroxyl free radicals in vitro, which shows antioxidant activity. Therefore, it is speculated that it can protect human hepatoma cell line (HepG2) and umbilical artery smooth muscle cell (HUASMC) against oxidative damage by hydrogen peroxide (H2O2). Methods: Oxidative damage cell models of HepG2 and HUASMC were induced by H2O2. HepG2 and HUASMC were divided into blank group, H2O2 injury group, TKPP treatment group, and glutathione (GSH) positive control group. Cell Counting Kit-8 (CCK-8) was used to detect cell viability. The level of total GSH and the amount of Nitric oxide (NO) secreted by cells were detected by specific kits. The gene and protein expressions of catalase (CAT) and superoxide dismutase (SOD) were detected by fluorescence quantitative PCR and Western Blot. Results: In these two kinds of cells, compared with the control group, the survival rate, total GSH level, and NO secretion, CAT and SOD gene and protein expressions were significantly decreased in the H2O2 damaged group. In the TKPP treatment group, the cell survival rate was significantly elevated with the increase of the polysaccharide concentration, and the total GSH level, NO secretion, CAT and SOD gene expression, and protein expression levels were also significantly increased. Conclusion: TKPP can improve the activities of HepG2 and HUASMC cells damaged by H2O2 and protect the cellular antioxidant system.

The association between DNA methylation of 6p21.33 and AHRR in blood and coronary heart disease in Chinese population.

BACKGROUND: Early detection could significantly improve the prognosis of coronary heart disease (CHD). In-invitro diagnostic technique may provide a solution when sufficient biomarkers could be identified. Pertinent associations between blood-based aberrant DNA methylation and smoking, the pathogenesis of atherosclerosis, and CHD have been robustly demonstrated and replicated, but that studies in Chinese populations are rare. The blood-based methylation of aryl-hydrocarbon receptor repressor (AHRR) cg05575921 and 6p21.33 cg06126421 has been associated with cardiovascular mortality in Caucasians. Here, we aim to investigate whether the AHRR and 6p21.33 methylation in the blood is associated with CHD in the Chinese population. METHODS: In this case-control study, 180 CHD patients recruited at their first registration in our study center, and 184 controls randomly selected from the people who participated in the annual health examination were enrolled. Methylation intensities of 19 CpG sites, including AHRR cg05575921, 6p21.33 cg06126421, and their flanking CpG sites, were quantified by mass spectrometry. The association between methylation intensities and CHD was estimated by logistic regression analyses adjusted for covariant. RESULTS: Compared to the controls, lower methylation of 6p21.33_CpG_4.5/cg06126421 was independently associated with increased odds of being a CHD patient (OR per - 10% methylation = 1.42 after adjustment for age, gender, and batch effect; p = 0.032 by multiple testing corrections). No association between blood-based AHRR methylation and CHD was found. CONCLUSIONS: 6p21.33 methylation exhibits a significant association with CHD. The combination of 6p21.33 methylation and conventional risk factors might be an intermediate step towards the early detection of CHD.

The diagnosis and molecular epidemiology investigation of avian hepatitis E in Shandong province, China.

BACKGROUND: Avian hepatitis E virus (HEV) is the pathogenic agent of big liver and spleen disease (BLS) and of hepatitis-splenomegaly syndrome (HSS) in chickens, which have caused economic losses to the poultry industry in China. In this study, 18 samples of BLS chickens were collected to reveal the molecular epidemiological characteristics of avian HEV in the province of Shandong, China. RESULTS: Gross and microscopic lesions of clinical samples were observed; then, virology detection and genetic analysis of avian HEV were performed. The results showed that there was significant swelling and rupture in the liver and that the spleen was enlarged. Microscopic lesions demonstrated obvious hemorrhage in the liver, with infiltration of heterophilic granulocytes, lymphocytes, and macrophages, as well as the reduction of lymphocytes in the spleen. Eleven of the 18 samples were positive for avian HEV, with a positive rate of 61.11%. More importantly, all avian HEV-positive samples were mixed infections: among these, the mixed infections of avian HEV and chicken infectious anemia virus (CIAV) and avian HEV and fowl adenovirus (FAdV) were the most common. Furthermore, the genetic evolution analysis showed that all avian HEV strains obtained here did not belong to the reported 4 genotypes, thus constituting a potential novel genotype. CONCLUSIONS: These results of this study further enrich the epidemiological data on avian HEV in Shandong, prove the genetic diversity of avian HEV in China, and uncover the complex mixed infections of avian HEV clinical samples.

ACEi/ARBs associate with lower incidence of gastrointestinal bleeding in peritoneal dialysis patients.

BACKGROUND: Gastrointestinal bleeding (GIB) is widespread in patients with impaired renal function. Whether angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers (ACEi/ARBs) potentially take a crucial role in avoiding GIB incidence among peritoneal dialysis (PD) patients is unknown. METHODS: Overall, 734 PD patients were enrolled after using propensity score matching. Kaplan-Meier analysis and COX regression were used to explore correlation between ACEi/ARBs and GIB. Competitive risk model was aimed to identify whether other events were confounding factors. Forest plot was applied to assess the influence of ACEI/ARBs on GIB incidence in different groups. RESULTS: During 8-year follow-up, 89 (12.13%) cases of GIB were recorded. Kaplan-Meier analysis revealed that the incidence of GIB among patients taking ACEi/ARBs was lower than those subjects who had not (log rank = 6.442, P = 0.011). After adjusted different confounding factors, administration of ACEi/ARBs was associated with lowered GIB incidence (adjusted HR = 0.49, 95% CI 0.32-0.77, P = 0.002). In competitive risk model, considering of other events, the incidence of GIB in two groups was still statistically significant (P = 0.010). Subgroup analysis showed ACEi/ARBs taking impeded GIB in the ≥ 60 age group (HR = 0.52, 95% CI 0.28-0.98, P = 0.040). CONCLUSION: PD patients who were submitted to ACEi/ARBs inclined to have a lower risk for GIB. In this regard, ACEi/ARBs offered a promising choice to GIB.

Proton pump inhibitor usage associates with higher risk of first episodes of pneumonia and peritonitis in peritoneal dialysis patients.

BACKGROUND: A large number of studies have shown that proton pump inhibitors (PPIs) are associated with infection events. Therefore, we retrospectively evaluated the association of PPI therapy with the occurrence of first pneumonia and peritoneal dialysis(PD)-related peritonitis events in the maintenance PD patients. METHODS: We collected PD patients in two large hospitals from January 1, 2012 to December 31, 2016, and divided them into the PPI group and the non-PPI group. Multivariate Cox proportional hazards models were applied to evaluate the cumulative incidence and hazard ratios (HRs). Inverse probability of treatment weight (IPTW) method was used to adjust for covariate imbalance between the two groups and further confirm our findings. RESULTS: Finally, 656 PD patients were included for data analysis, and the results showed that PPI usage was associated with an increased risk of pneumonia [HR 1.71; 95% CI 1.06-2.76; p = 0.027] and peritonitis [HR 1.73; 95% CI 1.24-2.40; p = 0.001]. IPTW-adjusted HRs for the association of PPIs with pneumonia and peritonitis were 1.58 (95% CI:1.18-2.12; p = 0.002) and 2.33 (95% CI:1.91-2.85; p < 0.001), respectively. Moreover, the competitive risk model proved that under the conditions of competition for other events(including transfer to hemodialysis therapy, kidney transplant, transfer from our research center, loss to follow-up, and death), the differences in endpoints events between the two groups were still statistically significant (p = 0.009, p < 0.001, respectively). CONCLUSIONS: PPIs was associated with an increased risk of first pneumonia and PD-related peritonitis events in PD patients, which reminds clinicians to be cautious when prescribing acid-suppressing drugs for PD patients.

Proton pump inhibitor usage is associated with higher all-cause mortality and CV events in peritoneal dialysis patients.

OBJECTIVES: A long period of inappropriate proton pump inhibitors (PPI) treatment has been proved to be associated with adverse prognosis in general population and hemodialysis patients. This study was conducted to clarify the impact of PPI usage on mortality and adverse cardiovascular (CV) events in peritoneal dialysis (PD) patients. METHODS AND DESIGN: This is a retrospective study. A total of 905 patients were enrolled from two PD centers, including 211 patients on PPI treatment and 618 patients not on PPIs. Kaplan-Meier curves were used to identify the incidence of adverse outcomes. Multivariate Cox regression models and inverse probability of treatment weighting (IPTW) were applied to analyze hazard ratios (HRs) for adverse outcomes. RESULTS: During follow-up, 162 deaths and 102 CV events were recorded. Kaplan-Meier curve demonstrated all-cause mortality (log-rank test p = .018) and CV events (log-rank test p = .024) were significantly higher in PPI usage group. Multivariate Cox regression models and IPTW showed that PPI usage was an indicator for all-cause mortality (HR = 1.35, 95%CI = 1.09-1.67, p = .006) and CV events (HR = 1.78, 95%CI = 1.35-2.32, p < .001). CONCLUSIONS: PPI usage is associated with higher all-cause mortality and CV events in PD patients. Clinicians are supposed to be more careful when using PPI and need to master the indications more rigorously in patients receiving PD treatment.

Role of M2-like macrophages in the progression of ovarian cancer.

In this study, we noninvasively assessed whether M2-like macrophages accelerate the progression of ovarian cancer by performing molecular imaging of ovarian cancer cells expressing enhanced firefly luciferase (Effluc) in living mice. First, murine ovarian cancer ID8 cells expressing Effluc (ID8/Effluc cells) were established by retroviral infection. Subsequently, macrophages were isolated from the peritoneal exudate of mice injected with thioglycollate medium and differentiated into M2-like macrophages by adding interleukin 4. To characterize these M2-like macrophages, F4/80 and cluster of differentiation 206 expression levels were determined. Then, the M2-like macrophages were co-cultured with the ID8/Effluc cells and bioluminescence imaging (BLI) of signals from the ID8/Effluc cells was completed. Additionally, migration and wound healing were assessed to evaluate the effects of conditioned medium (CM) from M2-like macrophages on ID8/Effluc cell motility. In the in vivo study, mice were first given either liposome-phosphate-buffered saline or liposome-clodronate (lipo-clodronate). After 24 h, ID8/Effluc cells were intraperitoneally injected into the mice and BLI was completed at the designed time points. Next, histological analysis was conducted to characterize the infiltrated tumor. Flow cytometric analysis revealed high levels of CD206 expression in the differentiated M2-like macrophages. Meanwhile, ID8/Effluc cells co-cultured with these M2-like macrophages proliferated rapidly in an M2-like macrophage, number-dependent manner. The migration of the ID8/Effluc cells was also increased by the application of CM from M2-like macrophages. In vivo BLI revealed that the growth rate of intraperitoneally injected ovarian cancer cells was inhibited following macrophage depletion by treatment with lipo-clodronate. M2-like macrophages accelerated the progression of ovarian cancer, suggesting they are a new therapeutic target for ovarian cancer and that ovarian cancer could be managed by altering the nature of communication between ovarian cancer and macrophages.

HMS1 interacts with HMS1I to regulate very-long-chain fatty acid biosynthesis and the humidity-sensitive genic male sterility in rice (Oryza sativa).

Environment-sensitive genic male sterility (EGMS) lines are used widely in two-line hybrid breeding in rice (Oryza sativa). At present, photoperiod-sensitive genic male sterility (PGMS) lines and thermo-sensitive genic male sterility (TGMS) lines are predominantly used in two-line hybrid rice, with humidity-sensitive genic male sterility (HGMS) lines rarely being reported. Here, it is shown that HUMIDITY-SENSITIVE GENIC MALE STERILITY 1 (HMS1), encoding a ß-ketoacyl-CoA synthase, plays key roles in the biosynthesis of very-long-chain fatty acids (VLCFAs) and HGMS in rice. The hms1 mutant displayed decreased seed setting under low humidity, but normal seed setting under high humidity. HMS1 catalyzed the biosynthesis of the C26 and C28 VLCFAs, contributing to the formation of bacula and tryphine in the pollen wall, which protect the pollen from dehydration. Under low-humidity conditions, hms1 pollen showed poor adhesion and reduced germination on the stigmas, which could be rescued by increasing humidity. HMS1-INTERACTING PROTEIN (HMS1I) interacted with HMS1 to coregulate HGMS. Furthermore, both japonica and indica rice varieties with defective HMS1 exhibited HGMS, suggesting that hms1 potentially could be used in hybrid breeding. The results herein reveal the novel mechanism of VLCFA-mediated pollen wall formation, which protects pollen from low-humidity stress in rice, and has a potential use in hybrid crop breeding.

Fabrication of Microfluidic Chips Based on an EHD-Assisted Direct Printing Method.

Microfluidic chips have been widely used in many areas such as biology, environmental monitoring, and micromixing. With the increasing popularity and complexity of microfluidic systems, rapid and convenient approaches for fabricating microfluidic chips are necessary. In this study, a method based on EHD (electrohydrodynamic)-assisted direct printing is proposed. Firstly, the principle of EHD-assisted direct printing was analyzed. The influence of the operating voltage and moving speed of the work table on the width of a paraffin wax model was studied. Then, two kinds of paraffin wax molds for micromixing with channel widths of 120 µm were prepared. A polydimethylsiloxane (PDMS) micromixer was fabricated by replicating the paraffin wax mold, and the micromixing of blue and yellow dye was realized. The results show that EHD-assisted direct printing can be used to make complex microscale structures, which has the potential to greatly simplify the manufacturing process.

Design and biomechanical characteristics of porous meniscal implant structures using triply periodic minimal surfaces.

BACKGROUND: Artificial meniscal implants can be used to replace a severely injured meniscus after meniscectomy and restore the normal functionality of a knee joint. The aim of this paper was to design porous meniscal implants and assess their biomechanical properties. METHODS: Finite element simulations were conducted on eight different cases including intact healthy knees, knee joints with solid meniscal implants, and knee joints with meniscal implants with two types of triply periodic minimal surfaces. Compression stresses, shear stresses, and characteristics of stress concentrated areas were evaluated using an axial compressive load of 1150 N and an anterior load of 350 N. RESULTS: Compared to the solid meniscal implant, the proposed porous meniscal implant produced lower levels of compression and shear stresses on the cartilage, which facilitated the cartilage to retain a semilunar characteristic similar to the natural meniscus. Moreover, both compression and shear stresses on the artificial cartilage were found to be sensitive to the pore properties of the meniscal implant. The meniscal implants with primitive surfaces (porosity: 41%) showed a better performance in disseminating stresses within the knee joint. CONCLUSION: The present commercial meniscal implant has the problem of equivalent biomechanical properties compared to natural menisci. The main advantage of the proposed porous structure is that it can be used to prevent excessive compression and shear stresses on the articular cartilages. This structure has advantages both in terms of mechanics and printability, which can be beneficial for future clinical applications.

Recent advances in microfluidic cell sorting techniques based on both physical and biochemical principles.

Microfluidic technologies for isolating cells of interest from a heterogeneous sample have attracted great attentions, due to the advantages of less sample consumption, simple operating procedure, and high separation accuracy. According to the working principles, the microfluidic cell sorting techniques can be categorized into biochemical (labeled) and physical (label-free) methods. However, the inherent drawbacks of each type of method may somehow influence the popularization of these cell sorting techniques. Using the multiple complementary isolation principles is a promising strategy to overcome this problem, therefore there appears to be a continuing trend to integrate two or more sorting methods together. In this review, we focus on the recent advances in microfluidic cell sorting techniques relied on both physical and biochemical principles, with emphasis on the mechanisms of cell separation. The biochemical cell sorting techniques enhanced by physical principles and the physical cell sorting techniques enhanced by biochemical principles, are first introduced. Then, we highlight on-chip magnetic-activated cell sorting, on-chip fluorescence-activated cell sorting, multi-step cell sorting and multi-principle cell sorting techniques, which are based on both physical and biochemical separation mechanisms. Finally, the challenges and future perspectives of the integrated microfluidics for cell sorting are discussed.

Alternative Splicing of Disabled-1 Controls Multipolar-to-Bipolar Transition of Migrating Neurons in the Neocortex.

Multipolar-to-bipolar transition (MBT) is crucial for the neuronal migration and positioning in the neocortex. Reelin-Disabled-1 (Dab1) signaling plays a pivotal role in neuronal migration, yet how Dab1 coordinatively regulates downstream molecules to affect MBT remains unclear. We have previously found that alternative splicing produces multiple Dab1 isoforms with different tyrosine motifs and differential ability to recruit downstream effectors. Here, we report that splicing of Dab1 exons 7 and 8 and 9bc dynamically regulates the inclusion and activities of Dab1 tyrosine motifs in the neocortex. By in utero electroporation, we show that expression of Dab1 isoforms missing exons 7 and 8 or retaining exons 9bc in WT neurons resulted in neuronal migration defects with attenuated Dab1 tyrosine phosphorylation, disrupted leading process extension, and disorientated multipolar neurons in the multipolar accumulation zone. Introducing the canonical Dab1 form, but not those missing exons 7 and 8 or retaining exons 9bc, into Dab1-deficient neurons promoted MBT and rescued neuronal migration defects, suggesting that alternative splicing of Dab1 modulates the tyrosine motif switch and mediates MBT of cortical neurons. Our study reveals a critical mechanism by which Dab1 alternative splicing coordinately controls MBT and neuronal migration in a spatiotemporal manner.