Stellar initial mass function varies with metallicity and time.

Most structural and evolutionary properties of galaxies strongly rely on the stellar initial mass function (IMF), namely the distribution of the stellar mass formed in each episode of star formation1-4. The IMF shapes the stellar population in all stellar systems, and so has become one of the most fundamental concepts of modern astronomy. Both constant and variable IMFs across different environments have been claimed despite a large number of theoretical5-7 and observational efforts8-15. However, the measurement of the IMF in Galactic stellar populations has been limited by the relatively small number of photometrically observed stars, leading to high uncertainties12-16. Here we report a star-counting result based on approximately 93,000 spectroscopically observed M-dwarf stars, an order of magnitude more than previous studies, in the 100-300 parsec solar neighbourhood. We find unambiguous evidence of a variable IMF that depends on both metallicity and stellar age. Specifically, the stellar population formed at early times contains fewer low-mass stars compared with the canonical IMF, independent of stellar metallicities. In more recent times, however, the proportion of low-mass stars increases with stellar metallicity. The variable abundance of low-mass stars in our Milky Way establishes a powerful benchmark for models of star formation and can heavily affect results in Galactic chemical-enrichment modelling, mass estimation of galaxies and planet-formation efficiency.

Ruxolitinib reduces severe CRS response by suspending CAR-T cell function instead of damaging CAR-T cells.

The therapeutic effect of CAR-T is often accompanied by sCRS, which is the main obstacle to the promotion of CAR-T therapy. The JAK1/2 inhibitor ruxolitinib has recently been confirmed as clinically effective in maintaining control over sCRS, however, its mechanism remains unclear. In this study, we firstly revealed that ruxolitinib significantly inhibited the proliferation of CAR-T cells without damaging viability, and induced an efficacy-favored differentiation phenotype. Second, ruxolitinib reduced the level of cytokine release not only from CAR-T cells, but also from other cells in the immune system. Third, the cytolytic activity of CAR-T cells was restored once the ruxolitinib was removed; however, the cytokines released from the CAR-T cells maintained an inhibited state to some degree. Finally, ruxolitinib significantly reduced the proliferation rate of CAR-T cells in vivo without affecting the therapeutic efficacy after withdrawal at the appropriate dose. We demonstrated pre-clinically that ruxolitinib interferes with both CAR-T cells and the other immune cells that play an important role in triggering sCRS reactions. This work provides useful and important scientific data for clinicians on the question of whether ruxolitinib has an effect on CAR-T cell function loss causing CAR-T treatment failure when applied in the treatment of sCRS, the answer to which is of great clinical significance.

Single-cell RNA sequencing reveals abnormal fluctuations in human eight-cell embryos associated with blastocyst formation failure.

Infertility has become a global health issue, with the number of people suffering from the disease increasing year by year, and ART offering great promise for infertility treatment. However, the regulation of early embryonic development is complicated and a series of processes takes place, including the maternal-to-zygotic transition. In addition, developmental arrest is frequently observed during human early embryonic development. In this study, we performed single-cell RNA sequencing on a biopsied blastomere from human eight-cell embryos and tracked the developmental potential of the remaining cells. To compare the sequencing results between different eight-cell embryos, we have combined the research data of this project with the data previously shared in the database and found that cells from the same embryo showed a higher correlation. Additionally, the transcriptome of embryos with blastocyst formation failure was significantly different from developed embryos, and the gene expression as well as cell signaling pathways related to embryonic development were also altered. In particular, the expression of some maternal and zygotic genes in the failed blastocyst formation group was significantly altered: the overall expression level of maternal genes was significantly higher in the failed blastocyst than the developed blastocyst group. In general, these findings provide clues for the causes of human embryonic arrest after the eight-cell stage, and they also provide new ideas for improving the success rate of ART in clinical practice.

SNHG16 lncRNAs are overexpressed and may be oncogenic in human gastric cancer by regulating cell cycle progression.

The small nucleolar RNA host gene 16 (SNHG16) has recently been shown to be a putative oncogene in gastric cancer (GC) and other cancer types, but how its four lncRNA variants are expressed in any physiological and pathological situation remains unknown. To investigate the expression and function of the four lncRNA variants of SNHG16, mainly the variant 1, in GC, we performed quantitative PCR to determine the RNA levels of the four variants in 60 GC tissue samples and several cell lines. We also studied how knocking down of SNHG16 with siRNA affected proliferation, apoptosis, cell cycle progression, as well as migration and invasion of GC cells. Our results showed that variants 1 and 4 were overexpressed in GC tissues compared with adjacent uninvolved tissues. Knockdown of the four variants, mainly the variant 1, enhanced apoptosis and inhibited cell cycle progression of a GC cell line by arresting the cells at the G1 phase. These cellular effects were associated not only with decreased protein levels of c-Myc, PCNA, cyclins D1, E1, A2 and B, as well as CDKs 2 and 6, but also with increased protein levels of the p21, p27 and p53. Knockdown of total SNHG16 lncRNAs also inhibited invasion and migration of the GC cells in vitro. These results collectively suggest that SNHG16 may be oncogenic in GC by regulating cell cycle progression and may serve as a GC biomarker.

Effect of exogenous gonadotropin on the transcriptome of human granulosa cells and follicular fluid hormone profiles.

BACKGROUND: Superovulation treatment had some adverse effects on maturity and development of oocytes. Can superovulation dose of gonadotropins (Gns) affect the transcriptome of granulosa cells and follicular fluid (FF) hormone levels? METHODS: One leading pre-ovulatory follicle per subject was used from three natural-cycle and four Gn-stimulated patients. Granulosa cells and FF samples were collected from the same leading follicle of each patient. RNA was extracted from granulosa cells and subjected to deep sequencing and analysis. Follicle-stimulating hormone (FSH), estradiol (E2), androstenedione (AND), testosterone (T), luteinizing hormone (LH), and progesterone (P4) levels in FF were measured by immunoassays. Student's t test was used for statistical analysis. RESULTS: A total of 715 genes were up-regulated, and 287 genes were down-regulated, in the Gn-stimulated group relative to the control group. Gene Ontology analysis revealed that the down-regulated genes were enriched in cell cycle and meiosis pathways, primarily those associated with follicle or oocyte maturation and quality. On the other hand, the up-regulated genes were enriched in functions related to immunity and cytokine-cytokine receptor interactions. Compared to the follicles of natural cycle, the E2 and LH concentrations were significantly reduced (P < 0.001), the P4 concentration was significantly increased (P = 0.003), and the concentrations of FSH, T and AND had no difference in the follicles of Gn-stimulated cycle. CONCLUSIONS: Cell cycle- and meiosis-associated genes were down-regulated by Gns stimulation, whereas immune- and cytokine-associated genes were up-regulated. Hormone levels were also affected by Gns stimulation. Compared with natural-cycle follicles,putative markers associated with oocyte quality and follicle maturation were significantly different from those in Gn-stimulated follicles. Hormone levels in follicles were compatible with the steroidogenic patterns of granulosa cell, which reflects the follicle maturation and oocyte quality.

Rhodium(iii)-catalysed cascade [3 + 2] annulation of N-aryloxyacetamides with 3-(hetero)arylpropiolic acids: synthesis of benzofuran-2(3H)-ones.

Herein, a cascade [3 + 2] annulation of N-aryloxyacetamides with 3-(hetero)arylpropiolic acids affording benzofuran-2(3H)-ones via rhodium(iii)-catalyzed redox-neutral C-H functionalization/isomerization/lactonization using an internal oxidative directing group O-NHAc was achieved. This catalytic system provides a regio- and stereoselective approach to synthesize (Z)-3-(amino(aryl)methylene)benzofuran-2(3H)-ones with exclusive Z configuration selectivity, acceptable yields and good functional group tolerance. Preliminary investigations on ultraviolet-visible and fluorescence behaviors reveal that the annulation products may be applied as a promising fluorescent probe for sensing metal cations, especially for cerium (Ce3+).

SIRT1 and FOXO Mediate Contractile Differentiation of Vascular Smooth Muscle Cells under Cyclic Stretch.

BACKGROUND/AIMS: Physiological mechanical stretch in vivo helps to maintain the quiescent contractile differentiation of vascular smooth muscle cells (VSMCs), but the underlying mechanisms are still unclear. Here, we investigated the effects of SIRT1 in VSMC differentiation in response to mechanical cyclic stretch. METHODS AND RESULTS: Rat VSMCs were subjected to 10%-1.25Hz-cyclic stretch in vitro using a FX-4000T system. The data indicated that the expression of contractile markers, including α-actin, calponin and SM22α, was significantly enhanced in VSMCs that were subjected to cyclic stretch compared to the static controls. The expression of SIRT1 and FOXO3a was increased by the stretch, but the expression of FOXO4 was decreased. Decreasing SIRT1 by siRNA transfection attenuated the stretch-induced expression of contractile VSMC markers and FOXO3a. Furthermore, increasing SIRT1 by either treatment with activator resveratrol or transfection with a plasmid to induce overexpression increased the expression of FOXO3a and contractile markers, and decreased the expression of FOXO4 in VSMCs. Similar trends were observed in VSMCs of SIRT1 (+/-) knockout mice. The overexpression of FOXO3a promoted the expression of contractile markers in VSMCs, while the overexpression of FOXO4 demonstrated the opposite effect. CONCLUSION: Our results indicated that physiological cyclic stretch promotes the contractile differentiation of VSMCs via the SIRT1/FOXO pathways and thus contributes to maintaining vascular homeostasis.

MicroRNA-34a targets Forkhead box j2 to modulate differentiation of endothelial progenitor cells in response to shear stress.

Flow shear stress plays important roles in modulating differentiation of endothelial progenitor cells (EPCs). MicroRNAs are crucial for diverse cellular processes, but the expressions and functions of microRNAs in EPCs responding to mechanical stimuli remain unclear. We sought to determine the effects of microRNA-34a (miR-34a) and a novel target Forkhead box j2 (Foxj2) on shear stress-induced EPC differentiation. Human umbilical cord blood-derived EPCs were exposed to laminar shear stress of 15dyn/cm(2) with parallel plate flow chamber system. Real time RT-PCR showed that shear stress significantly increased miR-34a expression, which was accompanied by the endothelial differentiation of EPCs. Whereas Foxj2, a putative target of miR-34a predicted by multiple algorithms, was suppressed in this process. Dual luciferase reporter assays, as well as miR-34a mimics and inhibitor treatment were used to confirm the interplay between miR-34a and Foxj2. Our results revealed an inverse correlation of miR-34a and Foxj2 expressions implicated in the endothelial differentiation of EPCs. MiR-34a contributed to this process by up-regulating the expressions of endothelial cell markers, and down-regulating smooth muscular cell markers. In addition, Foxj2 overexpression attenuated endothelial differentiation of EPCs, while Foxj2 siRNA had the opposite effect. These data suggested a unique mechanism that shear stress induces the expression of miR-34a, which targets to Foxj2 and promotes endothelial differentiation of EPCs. The results provide new insights into miR-34a/Foxj2 on shear stress-induced EPC differentiation.

PDGF-BB and TGF-{beta}1 on cross-talk between endothelial and smooth muscle cells in vascular remodeling induced by low shear stress.

Shear stress, especially low shear stress (LowSS), plays an important role in vascular remodeling during atherosclerosis. Endothelial cells (ECs), which are directly exposed to shear stress, convert mechanical stimuli into intracellular signals and interact with the underlying vascular smooth muscle cells (VSMCs). The interactions between ECs and VSMCs modulate the LowSS-induced vascular remodeling. With the use of proteomic analysis, the protein profiles of rat aorta cultured under LowSS (5 dyn/cm(2)) and normal shear stress (15 dyn/cm(2)) were compared. By using Ingenuity Pathway Analysis to identify protein-protein association, a network was disclosed that involves two secretary molecules, PDGF-BB and TGF-ß1, and three other linked proteins, lamin A, lysyl oxidase, and ERK 1/2. The roles of this network in cellular communication, migration, and proliferation were further studied in vitro by a cocultured parallel-plate flow chamber system. LowSS up-regulated migration and proliferation of ECs and VSMCs, increased productions of PDGF-BB and TGF-ß1, enhanced expressions of lysyl oxidase and phospho-ERK1/2, and decreased Lamin A in ECs and VSMCs. These changes induced by LowSS were confirmed by using PDGF-BB recombinant protein, siRNA, and neutralizing antibody. TGF-ß1 had similar influences on ECs as PDGF-BB, but not on VSMCs. Our results suggest that ECs convert the LowSS stimuli into up-regulations of PDGF-BB and TGF-ß1, but these two factors play different roles in LowSS-induced vascular remodeling. PDGF-BB is involved in the paracrine control of VSMCs by ECs, whereas TGF-ß1 participates in the feedback control from VSMCs to ECs.

SIRT1 and Connexin40 Mediate the normal shear stress-induced inhibition of the proliferation of endothelial cells co-cultured with vascular smooth muscle cells.

BACKGROUND: Shear stress imposed by blood flow directly impacts endothelial cells (ECs), which are simultaneously influenced by neighboring vascular smooth muscle cells (VSMCs). However, the mechanisms by which shear stress and VSMCs modulate EC proliferation remain to be elucidated. METHODS: ECs, cultured alone or co-cultured with VSMCs, were subjected to a normal level of laminar shear stress (NSS) of 15 dyne/cm(2) or kept under static conditions by using a parallel-plate flow chamber system, respectively. RESULTS: BrdU incorporation assay and flow cytometry revealed that NSS inhibited EC proliferation with or without VSMCs. Western blot analysis demonstrated that NSS down-regulated the expression of Connexin40 (Cx40) in both ECs cultured alone and ECs co-cultured with VSMCs, accompanied by the increased expression of SIRT1. Moreover, salermide, an inhibitor of SIRT1, as well as SIRT1-specifc siRNA transfection inhibited the effect of NSS on EC proliferation and Cx40 expression. In contrast, resveratrol, a SIRT1 activator, induced an alteration in ECs similar to the application of NSS. CONCLUSION: NSS inhibits the proliferation of ECs via SIRT1 and Cx40 in the presence or absence of VSMCs. The data suggest that NSS plays a protective role in vascular homeostasis by maintaining EC proliferation at a normal level.

A multidimensional nomogram combining clinical factors and imaging features to predict 1-year recurrence of low back pain with or without radicular pain after spinal manipulation/mobilization.

BACKGROUND: In this retrospective study, we aimed to develop a nomogram to predict recurrence during a 1-year period of spinal manipulation/mobilization (SM/M) in patients with low back pain (LBP) with greater pain intensity, more severe comorbid conditions, or a neuropathic component. METHODS: A total of 786 consecutive patients with LBP treated with SM/M as primary therapy were divided into training (n = 545) and validation (n = 241) sets. Cox regression analyses were used to assess the relative value of clinical factors and lumbar magnetic resonance imaging features associated with recurrence during the 1-year period. Predictors of recurrence with significant differences were used to construct a nomogram in the training set. We evaluated the performance of the model on the training and validation sets to determine its discriminative ability, calibration, and clinical utility. The prognostic value of the nomogram for predicting recurrence was assessed using Kaplan-Meier analysis and time-dependent receiver operating characteristic analyses. RESULTS: A nomogram comprising hospitalization time, previous history of LBP, disease duration, lumbar range of motion, lower extremity tendon reflex, muscle strength, ratio of herniation to uncompressed dural sac area, and Pfirrmann classification was established for recurrence during a 1-year period after SM/M in patients with LBP. Favorable calibration and discrimination were observed in the nomogram training and validation sets (C-index 0.753 and 0.779, respectively). Decision curve analysis confirmed the clinical utility of the nomogram. Over a 1-year period, the nomogram showed satisfactory performance in predicting recurrence in LBP after SM/M. CONCLUSION: We established and validated a novel nomogram that can accurately predict a patient's risk of LBP recurrence following SM/M. This realistic prognostic model may aid doctors and therapists in their decision-making process and strategy optimization for non-surgical treatment of LBP using SM/M.

Photoinduced fibrils formation of chicken egg white lysozyme under native conditions.

Recent findings showed that transiently accessing structurally native-like yet energetically higher conformational states is sufficient to trigger the formation of protein fibrils. Typically, these conformational states are made available through changing solvent conditions or introducing mutations. Here we show a novel way to initialize fibril formation for Chicken egg white lysozyme (CEWL) under native conditions via controlled UV illumination. Through a cassette of tryptophan-based photochemistry, the two terminal disulfide bonds in CEWL can be selectively reduced. The reduced CEWL is then converted to conformational states with the C-terminal fragment floppy upon thermal fluctuation. These states serve as precursors for the fibrillar aggregation. Intriguingly, the CEWL fibrils are stabilized by intermolecular disulfide bonds instead of noncovalent ß-sheet structures, distinct from the amyloid-like lysozyme fibrils reported before. Based on the experimental evidences and all-atom molecular dynamics simulation, we proposed a "runaway domain-swapping" model for the structure of the CEWL fibrils, in which each CEWL molecule swaps the C-terminal fragment into the complementary position of the adjacent molecule along the fibrils. We anticipate that this fibrillation mechanism can be extended to many other disulfide-containing proteins. Our study stands for the first example of formation of protein fibrils under native conditions upon UV illumination and poses the potential danger of low UV dose to organisms at the protein level.

Association of SIRT1 expression with shear stress induced endothelial progenitor cell differentiation.

Shear stress imposed by blood flow is crucial for differentiation of endothelial progenitor cells (EPCs). Histone deacetylase SIRT1 has been shown to play a pivotal role in many physiological processes. However, association of SIRT1 expression with shear stress-induced EPC differentiation remains to be elucidated. The present study was designed to determine the effect of SIRT1 on EPC differentiation induced by shear stress, and to seek the underlying mechanisms. Human umbilical cord blood-derived EPCs were exposed to laminar shear stress of 15 dyn/cm(2) by parallel plate flow chamber system. Shear stress enhanced EPC differentiation toward endothelial cells (ECs) while inhibited to smooth muscle cells (SMCs). The expressions of phospho-Akt, SIRT1 and histone H3 acetylation (Ac-H3) in EPCs were detected after exposure to shear stress for 2, 6, 12, and 24 h, respectively. Shear stress significantly activated Akt phosphorylation, augmented SIRT1 expression and downregulated Ac-H3. SIRT1 siRNA in EPCs diminished the expression of EC markers, but increased the expression of SMC markers, and resulted in upregulation of Ac-H3. Whereas, resveratrol, an activator of SIRT1, had the opposite effects on both EPC differentiation and histone H3 acetylation. Wortmannin, an inhibitor of PI3-kinase, suppressed endothelial differentiation of EPCs, decreased SIRT1, and upregulated Ac-H3 expression. In addition, SIRT1 promoted tube formation of EPCs in matrix gels. These results provided a mechanobiological basis of shear stress-induced EPC differentiation into ECs and suggest that PI3k/Akt-SIRT1-Ac-H3 pathway is crucial in such a process.

[Comparative study of determining the sites of airway obstruction in obstructive sleep apnea hypopnea syndrome between real-time CT scans and laryngofiberscope technology].

OBJECTIVE: To compare 256-layer spiral computed tomography (CT) scan in sleep and laryngofiberscope technology for locating obstructive sites of upper airway in patients with obstructive sleep apnea hypopnea syndrome, analyze their advantages and disadvantages and discuss the clinical application values. METHODS: A total of 59 patients with OSAHS diagnosed by polysomnography underwent spiral CT scan in awake and drug-induced sleep states and laryngofiberscope examination in awake state to assess the sites of airway obstruction. RESULTS: Real-time CT scans were completed successfully in all patients. There were airway obstruction at isolated retropalatal region (real-time CT revealing n = 26, laryngofiberscope revealing n = 34), retropalatal and retroglottal regions simultaneously (real-time CT revealing n = 19, laryngofiberscope revealing n = 10), retropalatal and epiglottal regions simultaneously (real-time CT revealing n = 6, laryngofiberscope revealing n = 2), retropalatal and retroglottal and epiglottal regions simultaneously (real-time CT revealing n = 7, laryngofiberscope revealing n = 3) and no airway obstruction (real-time CT revealing n = 1, laryngofiberscope revealing n = 10). There was not solitary airway obstruction at retroglottal or epiglottal region. The results of real-time CT scans and laryngofiberscope examination were statistically significant different in all regions, and real-time CT scanning compared with laryngofiberscope found more obstructive sites of upper airway [retropalatal region: 98.3% (n = 58) vs 81.4% (n = 48), χ(2) = 5.82, P < 0.05; retroglottal regions: 44.1% (n = 26) vs 22.0% (n = 13), χ(2) = 9.60, P < 0.01; epiglottal regions: 22.0% (n = 13) vs 8.5% (n = 5), χ(2) = 4.90, P < 0.05]. CONCLUSION: Compared with laryngofiberscope examination,real-time dynamic CT scans in drug-induced sleep state could get more information about anatomy changes of upper airway, providing relatively objective morphological basis for diagnosis and treatment of patients with OSAHS.

Gypenosides improve cognitive impairment induced by chronic cerebral hypoperfusion in rats by suppressing oxidative stress and astrocytic activation.

Gypenosides (GP), the saponin extract derived from the Gynostemma pentaphyllum Makino, a widely reputed medicinal plant in China, has been reported to have some neuroprotective effects. We used a rat model of chronic cerebral hypoperfusion to investigate the protective effects of GP on the cortex and hippocampal CA1 region and the underlying mechanisms for its inhibition of cognitive decline. Daily doses of 100 and 200 mg/kg GP were orally administered to adult male Sprague-Dawley rats for 61 days after inducing cerebral hypoperfusion experimentally, and spatial learning and memory were assessed using the Morris water maze. Antioxidative capability was measured biochemically. The levels of lipid peroxidation and oxidative DNA damage were assessed by immunohistochemical staining for 4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine, respectively. Activated astrocytes were assessed by immunohistochemical staining and western blotting with GFAP antibodies. Rats receiving 200 mg/kg GP had better spatial learning and memory than saline-treated rats. GP 200 mg/kg/day were found to markedly enhance antioxidant abilities, decrease lipid peroxide products and oxidative DNA damage, and reduce the activation of inflammatory astrocytes. However, GP 100 mg/kg had no significant effects. GP may have therapeutic potential for the treatment of dementia induced by chronic cerebral hypoperfusion and further evaluation is warranted.

[Staged surgery of Sanders type â £ calcaneal fractures with soft tissue three-degree swelling].

OBJECTIVE: To compare the clinical efficacy of staged surgery on Sanders Ⅳ calcaneal fractures with soft tissue Ⅲ swelling. METHODS: The clinical data of 76 patients with Sanders type Ⅳ closed calcaneal fracture with soft tissue three-degree swelling treated from June 2017 to May 2020 was retrospectively analyzed, including 54 males and 22 females, aged from 25 to 50 (38.16±10.24) years. The patients were divided into observation group and control group according to different treatment methods. Twenty-four patients in the observation group were treated by staged surgery stageⅠclosed prying traction reduction and Kirschner wire fixation, stageⅡopen reduction and internal fixation with titanium plate, including 17 males and 7 females, aged from 25 to 50 (36.12±9.56) years. There were 52 patients in the control group, including 37 males and 15 females, aged from 25 to 50 (38.32±10.67) years, these patients were treated with open reduction and internal fixation with titanium plate after the dermatoglyphic signs appeared. The swelling subsidence time, the length of hospitalization days, and the incidence of postoperative incision complications were compared between two groups. The Bhler angle, Gissane angle, and calcaneal varus angle were measured by X-ray before and 6 months after operation. American Orthopedic Foot and Ankle Society (AOFAS) about the ankle hindfoot score was used to evaluate the clinical efficacy. RESULTS: All 76 patients were followed up for 8 to 12 (9.52±2.01) months. The swelling subsidence time and hospitalization days in observation group were (12.12± 3.24) d and (24.53±6.44) d, respectively, which in control group were (15.16±4.16) d and (29.46±9.61) d, with statistical difference between two groups (P<0.05). Postoperative 6 months, Bhler angle, Gissane angle and calcaneal varus angle were (31.33±10.15)°, (145.34±8.04) ° and (10.31±3.23) ° in observation group, while those in control group were (20.24±8.23) °, (165.28±10.29) °and (21.24±5.27) °, with statistical difference between two groups (P<0.05). And there was significant difference in all patients between before and 6 months after operation (P<0.05). The AOFAS score of the observation group and control group were 71.76±9.84 and 57.23±10.76 at 6 months after operation, with significant different between two groups (P< 0.05). The excellent rate of observation group was significantly higher than that of control group (P<0.05). CONCLUSION: Compared with open reduction and internal fixation with titanium plate after the appearance of dermatoglyphic signs, staged surgery for Sanders type Ⅳ calcaneal fractures with soft tissue three-swelling does not increase the risk of soft tissue complications, and can significantly shorten the patient's swelling subsidence time and hospitalization days, improve the quality of fracture reduction and short term function, and relieve pain.

[Alternative Splicing Analysis of LACTB Gene and Expression Characteristics of Different Transcripts in Leukemia Cell Lines].

OBJECTIVE: To detect the expression of different transcripts of lactamase ß（LACTB) gene in leukemic cell lines. METHODS: NCBI website and DNAstar software were used to detect the Bioinformatics analysis of LACTB. The expression of different transcripts of LACTB gene in leukemic cell lines (THP-1, HL60, K562, U937, Jurkat and Raji) was detected by reverse transcription PCR (RT-PCR), DNA and clone sequencing; the expression of different transcripts of LACTB gene in leukemic cell lines was detected by Quantitative Real-time PCR. RESULTS: There were a variety of splicing isomers in LACTB, and it could produce a variety of protein isomers with conserved N-terminal and different C-terminal, moreover, there were many splice isoforms of LACTB in leukemia cell lines, and there were different expression patterns in different cell lines, including XR1, V1, V2 and V3. The expression of total LACTB showed high in HL60 cells, while low in Raji cells, and the difference was statistically significant (P<0.05). The V1 was high expression in U937 cells but low in Raji cells, and the difference was statistically significant (P<0.05). V2 was high expression in HL60 cells but lowly in Raji cells, and the difference was statistically significant (P<0.05). The expression of V3 was low in THP-1 cells, which was significantly different as compared with that in normal bone marrow (P<0.05). CONCLUSION: The reaserch found that there are many splice isomers of LACTB in leukemic cell lines, and there are different expression patterns in different cell lines.

Cyclic strain modulates migration and proliferation of vascular smooth muscle cells via Rho-GDIalpha, Rac1, and p38 pathway.

Cyclic strain is an important inducer of proliferation and migration of vascular smooth muscle cells (VSMCs) which are involved in vascular remodeling during hypertension. However, its mechanism remains to be elucidated. VSMCs of rat aorta were exposed to cyclic strains in vitro with defined parameters, the static, 5%-strain (physiological) and 15%-strain (pathological), at 1.25 Hz for 24 h respectively. Then the possible signaling molecules participated in strain-induced VSMC migration and proliferation were investigated. The results showed that 15%-strain significantly increased VSMC migration and proliferation in comparison with 5%-strain. Expression of Rho GDP dissociation inhibitor alpha (Rho-GDIalpha) was repressed by 15%-strain, but expressions of phospho-Rac1 and phospho-p38 were increased. Expressions of phospho-Akt and phospho-ERK1/2 were similar between the static, 5%-strain and 15%-strain groups. Rho-GDIalpha "knock-down" by target siRNA transfection increased migration and proliferation of VSMCs, and up-regulated phosphorylation of Rac1 and p38 in all groups. Rac1 "knock-down" repressed migration and proliferation of VSMCs, down-regulated phosphorylation of p38, but had no effect on Rho-GDIalpha expression. When siRNAs of Rho-GDIalpha and Rac1 were co-transfected to VSMCs, the expressions of Rho-GDIalpha and phospho-Rac1 were both decreased, and the effects of Rho-GDIalpha "knock-down" were blocked. Rho-GDIalpha "knock-down" promoted while Rac1 "knock-down" postponed the assembly of stress fibers and focal adhesions in static. The results demonstrate that the pathological cyclic strain might induce migration and proliferation of VSMCs via repressing expression of Rho-GDIalpha, which subsequently verified phosphorylations of Rac1 and p38.

Phytotoxic mechanism of allelochemical liquiritin on root growth of lettuce seedlings.

As the main active ingredient of the traditional Chinese medicine Glycyrrhiza uralensis Fisch, liquiritin has multiple biological activities, including anti-inflammatory, antihepatotoxicity, immune regulation, anti-virus and anti-cancer. In addition, liquiritin has been recognized as an allelochemical that displays markedly inhibitory effects on the growth of target plants, G. uralensis and lettuce. However, its phytotoxic mechanism remains unknown. In the present study, the mode of action of liquiritin against root growth of lettuce seedling was researched. After treatments with liquiritin, the cell division in root tips of lettuce seedlings was partly arrested, and the cell viability and root vitality were obviously lost. At the same time, overproduction of reactive oxygen species (ROS), malondialdehyde (MDA) and proline (Pro) in lettuce seedlings were induced by liquiritin. The results indicated that the phytotoxic effects of liquiritin was probably dependent on the induction of ROS overproduction, resulting in membrane lipids peroxidation following with cell death and mitosis process disorder.

Single-cell DNA methylation sequencing reveals epigenetic alterations in mouse oocytes superovulated with different dosages of gonadotropins.

BACKGROUND: Epigenetic abnormalities caused by superovulation have recently attracted increasing attention. Superovulation with exogenous hormones may prevent oocytes from establishing an appropriate epigenetic state, and this effect may extend to the methylation programming in preimplantation embryos, as de novo DNA methylation is a function of developmental stage of follicles and oocyte size. Follicle-stimulating hormone (FSH) and human menopausal gonadotropin (hMG) are common gonadotropins used for superovulation, and appropriate concentrations of these gonadotropins might be necessary. However, no systematic study on the effects of DNA methylation alterations in oocytes associated with superovulation with different dosages of FSH/hMG at the single-cell level has yet been reported. In the current study, different dosages of FSH/hMG combined with human chorionic gonadotropin (hCG) were used in female mice to generate experimental groups, while naturally matured oocytes and oocytes superovulated with only hCG were respectively used as controls. Single-cell level DNA methylation sequencing was carried out on all these matured oocytes. RESULTS: In this study, we revealed that the genome-wide methylation pattern and CG methylation level of the maternal imprinting control regions of all mature oocytes were globally conserved and stable. However, methylation alterations associated with superovulation were found at a specific set of loci, and the differentially methylated regions (DMRs) mainly occurred in regions other than promoters. Furthermore, some of the annotated genes in the DMRs were involved in biological processes such as glucose metabolism, nervous system development, cell cycle, cell proliferation, and embryo implantation and were altered in all dosages of FSH/hMG group (for example, Gfod2 and SYF2). Other genes were impaired only after high gonadotropin dosages (for instance, Sox17 and Phactr4). CONCLUSIONS: In conclusion, the current study addressed the effects of superovulation on DNA methylation from the perspective of different dosages of gonadotropins at the single-cell level. We found that the genome-wide DNA methylation landscape was globally preserved irrespective of superovulation or of the kind and dosage of gonadotropins used, whereas the methylation alterations associated with superovulation occurred at a specific set of loci. These observed effects reflect that superovulation recruits oocytes that would not normally be ovulated or that have not undergone complete epigenetic maturation. Our results provide an important reference for the safety assessment of superovulation with different dosages of gonadotropins. However, it should be noted that this study has some limitations, as the sample number and library coverage of analyzed oocytes were relatively low. Future studies with larger sample sizes and high-coverage libraries that examine the effects of superovulation on embryo development and offspring health as well as the underlying mechanisms are still needed.