Eco-friendly management of Meloidogyne incognita in cadmium-contaminated soil by using nematophagous fungus Purpureocillium lavendulum YMF1.683: Efficacy and mechanism.

Root-knot nematodes (RKNs) are distributed globally, including in agricultural fields contaminated by heavy metals (HM), and can cause serious crop damages. Having a method that could control RKNs in HM-contaminated soil while limit HM accumulation in crops could provide significant benefits to both farmers and consumers. In this study, we showed that the nematophagous fungus Purpureocillium lavendulum YMF1.683 exhibited a high nematocidal activity against the RKN Meloidogyne incognita and a high tolerance to CdCl2. Comparing to the P. lavendulum YMF1.838 which showed low tolerance to Cd2+, strain YMF1.683 effectively suppressed M. incognita infection and significantly reduced the Cd2+ uptake in tomato root and fruit in soils contaminated by 100 mg/kg Cd2+. Transcriptome analyses and validation of gene expression by RT-PCR revealed that the mechanisms contributed to high Cd-resistance in YMF1.683 mainly included activating autophagy pathway, increasing exosome secretion of Cd2+, and activating antioxidation systems. The exosomal secretory inhibitor GW4869 reduced the tolerance of YMF1.683 to Cd2+, which firstly demonstrated that fungal exosome was involved in HM tolerance. The up-regulation of glutathione synthesis pathway, increasing enzyme activities of both catalase and superoxide dismutase also played important roles in Cd2+ tolerance of YMF1.683. In Cd2+-contaminated soil, YMF1.683 limited Cd2+-uptake in tomato by up-regulating the genes of ABCC family in favor of HM sequestration in plant, and down-regulating the genes of ZIP, HMA, NRAMP, YSL families associated with HM absorption, transport, and uptake in plant. Our results demonstrated that YMF1.683 could be a promising bio-agent in eco-friendly management of M. incognita in Cd2+ contaminated soils.

Hyperthermia enhances the efficacy of chemotherapeutic drugs in heat-sensitive cells through interfering with DNA damage repair.

Background: Hyperthermic intraperitoneal chemotherapy (HIPEC) has been shown to be clinically effective, but the mechanisms by which hyperthermia enhances the sensitivity of cells to chemotherapeutic drugs has not yet been elucidated. Methods: To identify the key molecules involved in thermochemotherapy, this study used mass spectrometry (MS)-based quantitative proteomics technology to analyze the effects of thermochemotherapy on the heat-sensitive ovarian cancer cell line A2780. We divided the A2780 cell line into four groups, one group served as blank control, and the other three groups were stimulated by oxaliplatin, stimulated by hyperthermia at 42 ℃, and stimulated by hyperthermia combined with oxaliplatin. Samples were then collected for tandem mass tag (TMT) labeling, high-performance liquid chromatography fractionation, and MS-based quantitative proteomics for analysis The differentially expressed proteins were quantitatively compared and identified, and Gene Ontology (GO) assessment and cluster analyses were performed. Finally, the above MS results were verified again by Western blotting experiments. Results: A total of 349 differentially expressed proteins were identified between cells treated with chemotherapy alone (group B) and cells treated with a combination of chemotherapy and hyperthermia (group D). There were 145 upregulated proteins and 204 downregulated proteins. Among the top 20 proteins with significantly different expression levels, nearly two-thirds were involved in DNA damage repair. These proteins were subsequently verified by Western blot analysis. Indeed, consistent with MS data, the expression of the RBL1 protein was significantly upregulated in cells treated with thermochemotherapy (group D) compared to cells treated with chemotherapy alone (group B). Conclusions: In heat-sensitive ovarian cancer cells, the damage repair of tumor cell DNA is disturbed by hyperthermia, making it unable to fully repair when damaged by chemotherapeutic drugs. As a result, hyperthermia enhances the efficacy of chemotherapeutic drugs. RBL1, as a tumor suppressor gene, may be associated with the repair of DNA damage, and thus it may be a key target for hyperthermia to enhance the sensitivity of thermosensitive cells to chemotherapeutic drugs.

Comparative genomics analysis of strains from diverse sources reveals the evolutionary relationship of Aeromonas veronii.

Aeromonas veronii (A. veronii, AV) strains are emerging zoonotic and aquatic pathogens, yet we know very little about their genomics. This study aims to utilize comparative genomics to investigate the intraspecific genetic diversity, differences in virulence factors and evolutionary mechanisms of A. veronii strains from diverse sources and to fundamentally demonstrate their pathogenic mechanisms. We conducted comparative genomics analysis of 39 A. veronii strains from different sources and found that 1993 core genes are shared by these strains and that these shared core genes may be necessary to maintain the basic characteristics of A. veronii. Additionally, phylogenetic relationship analysis based on these shared genes revealed that a distant relationship between the AMC34 strain and the other 38 strains but that, the genetic relationship among the 38 strains is relatively close, indicating that AMC34 may not belong to A. veronii. Furthermore, analysis of shared core genes and average nucleotide identity (ANI) values showed no obvious correlation with the location of A. veronii isolation and genetic relationship. Our research indicates the evolutionary mechanism of A. veronii from different sources and provides new insights for a deeper understanding of its pathogenic mechanism.

[Analysis of the effect of surgical treatment of periprosthetic femoral fractures after hip replacement].

OBJECTIVE: To analyze and compare the clinical efficacy of different types of surgical treatment of periprosthetic femoral fracture(PFF) after hip arthroplasty (HA). METHODS: From September 2010 to September 2016, 47 patients (47 hips) with periprosthetic fractures after total hip arthroplasty were retrospectively analyzed, including 13 males and 34 females. According to Vancouver classification, there were 2 patients with type AG, 17 patients with type B1, 19 patients with type B2, 7 patients with type B3 and 2 patients with type C. The age of patients ranged from 56 to 94 (71.5±8.3) years. After admission, nutritional risk screening (NRS2002) was used to assess the nutritionalstatus of the patients. Eighteen patients (38%) had malnutrition risk (NRS>3 points). After admission, the patients were given corresponding surgical treatment according to different types. Intraoperative blood loss was recorded. Harris score was used to evaluate the hip function. VAS pain score was performed on admission and after operation. RESULTS: All the 47 patients were followed up for 19 to 62 (34±11) months. The Harris scores were (41.8±12.1) and (89.0±2.6) respectively before and 1 year after operation, and the difference was statistically significant (t=29.7, P<0.01). The VAS pain scores were (8.0±0.6) and (0.5±0.6) respectively before and 1 year after operation, and the difference was statistically significant(t=80.7, P<0.01). The intraoperative blood loss was (730±68) ml and (688±127) ml in patients with type B1 malnutrition risk and patients without malnutrition risk, and the difference was statistically significant (t=4.6, P<0.05);the intraoperative blood loss was (916±118) ml and (884±88) ml in patients with type B2 malnutrition risk and patients without malnutrition risk, and the difference was statistically significant (t=8.7, P<0.05). At the last follow-up, all the fractures were healed and the force line of lower limbs was good. No loosening, displacement, fracture of internal fixation, loosening and dislocation of prosthesis occurred during the follow-up period. CONCLUSION: The treatment of hip periprosthetic fracture patients should be based on the general situation of patients, imaging data, intraoperative correction classification, etc. to develop individualized treatment plan in line with patients. For patients with preoperative malnutrition risk, preoperative nutritional intervention may reduce intraoperative bleeding.

miR­302c­3p and miR­520a­3p suppress the proliferation of cervical carcinoma cells by targeting CXCL8.

The aim of the present study was to identify the differentially expressed microRNAs (miRs) in cervical carcinoma (CC) tissues and cells and to explore the function of miR­302c­3p and miR­520a­3p in the proliferation of CC cells. Potential dysregulated miRNAs in CC tissues and tumour­adjacent tissues were detected. Reverse transcription­quantitative PCR (RT­qPCR) was performed to determine the expression of miR­302c­3p, miR­520a­3p and CXCL8 in CC tissues and cell lines. The target genes of the miRNAs were predicted using miRTarBase and verified by luciferase reporter assays. RT­qPCR and western blotting were performed to measure the expression of C­X­C motif ligand (CXCL)8 after transfection. The effect on proliferation was verified by Cell Counting Kit assay and ethynyl­2­deoxyuridine staining. Flow cytometry was utilised to assess the effect on apoptosis. In the present study, miR­302c­3p and miR­520a­3p were markedly downregulated in CC cell lines compared to the normal cervical cell line H8. Functionally, overexpression of miR­302c­3p and/or miR­520a­3p inhibited proliferation and promoted the apoptosis of CC cell lines in vitro, while the knockdown of miR­302c­3p and/or miR­520a­3p had the opposite effect. Furthermore, miR­302c­3p and miR­520a­3p could both bind to CXCL8. Inhibition of CXCL8 in combination with miR­302c­3p and/or miR­520a­3p overexpression exerted proliferation­suppressive and apoptosis­stimulating effects on CC cells, whereas restoring CXCL8 attenuated the miR­302c­3p­ and miR­520a­3p­induced anti­proliferative and pro­apoptotic effects. miR­302c­3p and miR­520a­3p suppress the proliferation of CC cells by downregulating the expression of CXCL8, which may provide a novel target for the treatment of CC.

Comparative proteomic analysis reveals novel potential virulence factors of Aeromonas veronii.

Aeromonas veronii is an important zoonotic and aquatic pathogen. An increasing number of reports indicate that it has caused substantial economic losses in the aquaculture industry, in addition to threatening human health. However, little is known about its pathogenesis. Exploration of new virulence factors of A. veronii would be helpful for further understanding its pathogenesis. Hence, we comparatively analyzed the proteomes of virulent, attenuated, and avirulent strains of A. veronii using tandem mass tag (TMT) protein labeling and found numerous proteins either up- or downregulated in the virulent strain. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that these differentially expressed proteins (DEPs) were involved mainly in pathways associated with bacterial chemotaxis and microbial metabolism in diverse environments. Furthermore, the expression levels of lysine decarboxylase, endoribonuclease, maltoporin, pullulanase, and aerolysin were positively correlated with the virulence of the strains, suggesting that their function may be closely related to the virulence of A. veronii. The results of qRT-PCR and multiple reaction monitoring for some DEPs were consistent with the results of TMT protein labeling. These results suggest that these DEPs may be novel potential virulence factors and will help to further understand the pathogenesis of A. veronii.

CircATRNL1 activates Smad4 signaling to inhibit angiogenesis and ovarian cancer metastasis via miR-378.

Ovarian cancer is one of the most frequent carcinomas in females, and the occurrence rate is still rising despite many advances made. The pathogenesis of ovarian cancer remains greatly unclear. Here, we investigated the mechanisms of ovarian cancer, with the focus on circATRNL1. Human ovarian cancer tissues and cell lines were used to examine levels of circATRNL1, miR-378, Smad4, AKT, and other proliferation-related and migration-related proteins. Cellular assays were used to determine cancer cell proliferation, invasion, migration, apoptosis, and angiogenesis. We validated the interactions of circATRNL1/miR-378 and miR-378/Smad4, and a mouse tumor xenograft model was employed to assess the effect of circATRNL1 on tumor growth and metastasis in vivo. We found that circATRNL1 was decreased while miR-378 was increased in human ovarian cancer tissues and cells. circATRNL1 bound to miR-378 while miR-378 directly targeted Smad4. Overexpression of circATRNL1 or knockdown of miR-378 suppressed angiogenesis and ovarian cancer cell proliferation, invasion, and migration via decreasing proliferation- and migration-related proteins via miR-378 or Smad4, respectively. Overexpression of circATRNL1 restrained ovarian cancer growth and abdominal metastasis in vivo. Our findings indicate that circATRNL1 acts as a miR-378 sponge to active Smad4 signaling and suppresses angiogenesis and ovarian cancer metastasis.

Fructose-coated Angstrom silver inhibits osteosarcoma growth and metastasis via promoting ROS-dependent apoptosis through the alteration of glucose metabolism by inhibiting PDK.

Osteosarcoma is a common malignant bone cancer easily to metastasize. Much safer and more efficient strategies are still needed to suppress osteosarcoma growth and lung metastasis. We recently presented a pure physical method to fabricate Ångstrom-scale silver particles (AgÅPs) and determined the anti-tumor efficacy of fructose-coated AgÅPs (F-AgÅPs) against lung and pancreatic cancer. Our study utilized an optimized method to obtain smaller F-AgÅPs and aimed to assess whether F-AgÅPs can be used as an efficient and safe agent for osteosarcoma therapy. We also investigated whether the induction of apoptosis by altering glucose metabolic phenotype contributes to the F-AgÅPs-induced anti-osteosarcoma effects. Methods: A modified method was developed to prepare smaller F-AgÅPs. The anti-tumor, anti-metastatic and pro-survival efficacy of F-AgÅPs and their toxicities on healthy tissues were compared with that of cisplatin (a first-line chemotherapeutic drug for osteosarcoma therapy) in subcutaneous or orthotopic osteosarcoma-bearing nude mice. The pharmacokinetics, biodistribution and excretion of F-AgÅPs were evaluated by testing the levels of silver in serum, tissues, urine and feces of mice. A series of assays in vitro were conducted to assess whether the induction of apoptosis mediates the killing effects of F-AgÅPs on osteosarcoma cells and whether the alteration of glucose metabolic phenotype contributes to F-AgÅPs-induced apoptosis. Results: The newly obtained F-AgÅPs (9.38 ± 4.11 nm) had good stability in different biological media or aqueous solutions and were more effective than cisplatin in inhibiting tumor growth, improving survival, attenuating osteolysis and preventing lung metastasis in osteosarcoma-bearing nude mice after intravenous injection, but were well tolerated in normal tissues. One week after injection, about 68% of F-AgÅPs were excreted through feces. F-AgÅPs induced reactive oxygen species (ROS)-dependent apoptosis of osteosarcoma cells but not normal cells, owing to their ability to selectively shift glucose metabolism of osteosarcoma cells from glycolysis to mitochondrial oxidation by inhibiting pyruvate dehydrogenase kinase (PDK). Conclusion: Our study suggests the promising prospect of F-AgÅPs as a powerful selective anticancer agent for osteosarcoma therapy.

Trapping and Manipulation of Single Cells in Crowded Environments.

Optical tweezers provide a powerful tool to trap and manipulate living cells, which is expected to help people gain physiological insights at single-cell level. However, trapping and manipulating single cells under crowded environments, such as blood vessels and lymph nodes, is still a challenging task. To overcome this issue, an annular beam formed by the far-field Bessel beam is introduced to serve as an optical shield to isolate the target cells from being disturbed. With this scheme, we successfully trapped and manipulated single blood cells in a crowded environment. Furthermore, we demonstrated manipulation of two lymphocytes ejected from a lymph node independently with dual-trap optical tweezers, which paves the way for exploring cell interactions under living conditions. Such technique might be helpful in the study of how natural killer cells response to virus-infected cells or cancer cells.

The association between fibroblast growth factor receptor 1 gene amplification and lung cancer: a meta-analysis.

INTRODUCTION: Identifying target oncogenic alterations in lung cancer represents a major development in disease management. We examined the association of fibroblast growth factor receptor 1 (FGFR1) gene amplification with pathological characteristics and geographic region. MATERIAL AND METHODS: We conducted a meta-analysis of studies published between January 2010 and October 2016. Relative risks (RR) and corresponding 95% confidence intervals (CI) were calculated regarding the rate of FGFR1 amplification in different lung cancer types and geographic region. RESULTS: Twenty-three studies (5252 patients) were included. There was heterogeneity between studies. However, in subgroup analyses for squamous cell carcinoma (SCC), small cell lung cancer (SCLC), studies using the same definition of FGFR1 amplification, and those from Australia, no significant heterogeneity was detected. The prevalence of FGFR1 amplification in these studies ranged from 4.9% to 49.2% in non-small cell lung cancer (NSCLC), 5.1% to 41.5% in SCC, 0% to 14.7% in adenocarcinoma, and 0% to 7.8% in SCLC. The prevalence of FGFR1 amplification was significantly higher in SCC than in adenocarcinoma (RR = 5.2) and SCLC (RR = 4.2). The prevalence of FGFR1 amplification ranged from 5.6% to 22.2% in Europe, 4.1% to 18.2% in the United States, 7.8% to 49.2% in Asia, and 14.2% to 18.6% in Australia. The rate of FGFR1 amplification was higher in Asians than in non-Asians (RR = 1.9) in NSCLC. CONCLUSIONS: These results suggest that FGFR1 amplification occurs more frequently in SCC and in Asians. FGFR1 amplification may be a potential new therapeutic target for specific patients and lung cancer subtypes.

Expression of the lncRNA ZFAS1 in cervical cancer and its correlation with prognosis and chemosensitivity.

OBJECTIVE: To investigate the expression of the lncRNA ZFAS1 in cervical cancer and its relationship with patient prognosis and cervical cancer cell chemosensitivity. METHODS: The expression of ZFAS1 in cervical cancer tissues and cell lines was detected by qRT-PCR. The cervical cancer CaSki and the HeLa cell lines were transfected to be divided into Blank, siR-Control, and siR-ZFAS1 groups. MTT, wound-healing, and transwell assays were used to evaluate cell biological function. Cisplatin with different concentrations was used to treat cells in different transfection groups, and MTT assays were used to detect the cell growth inhibition rate and the half-inhibitory concentration (IC50) of cisplatin was measured. Cell apoptosis was determined by flow cytometry. A xenograft mouse model was used to investigate the effects of siR-ZFAS1 on the chemosensitivity to cisplatin. RESULTS: ZFAS1 was significantly upregulated in cervical cancer tissues and cell lines, and increased ZFAS1 levels led to poor prognoses in patients. In addition, cells in the siR-ZFAS1 group showed remarkably reduced ZFAS1 expression as well as cell proliferation, invasion and migration. After being treated with cisplatin at different concentrations, cells in the siR-ZFAS1 group had dramatically increased cell growth inhibition and apoptosis but lower cisplatin IC50s. In addition, siR-ZFAS1 reduced the volumes and weights of tumors in nude mice treated with cisplatin and enhanced the chemosensitivity of cervical cancer cells to cisplatin. CONCLUSION: The lncRNA ZFAS1 was upregulated in cervical cancer tissues, and its high expression indicated a poor prognosis. Silencing ZFAS1 may inhibit cell proliferation, migration and invasion and enhance cisplatin chemosensitivity.

HLA-A*24:02 as a common risk factor for antiepileptic drug-induced cutaneous adverse reactions.

OBJECTIVE: To investigate the involvement of human leukocyte antigen (HLA) loci in aromatic antiepileptic drug-induced cutaneous adverse reactions. METHODS: A case-control study was performed to detect HLA loci involved in aromatic antiepileptic drug-induced Stevens-Johnson syndrome in a southern Han Chinese population. Between January 1, 2006, and December 31, 2015, 91 cases of Stevens-Johnson syndrome induced by aromatic antiepileptic drugs and 322 matched drug-tolerant controls were enrolled from 8 centers. Important genotypes were replicated in cases with maculopapular eruption and in the meta-analyses of data from other populations. Sequence-based typing determined the HLA-A, HLA-B, HLA-C, and HLA-DRB1 genotypes. RESULTS: HLA-B*15:02 was confirmed as strongly associated with carbamazepine-induced Stevens-Johnson syndrome (p = 5.63 × 10-15). In addition, HLA-A*24:02 was associated significantly with Stevens-Johnson syndrome induced by the aromatic antiepileptic drugs as a group (p = 1.02 × 10-5) and by individual drugs (carbamazepine p = 0.015, lamotrigine p = 0.005, phenytoin p = 0.027). Logistic regression analysis revealed a multiplicative interaction between HLA-B*15:02 and HLA-A*24:02. Positivity for HLA-A*24:02 and/or HLA-B*15:02 showed a sensitivity of 72.5% and a specificity of 69.0%. The presence of HLA-A*24:02 in cases with maculopapular exanthema was also significantly higher than in controls (p = 0.023). Meta-analysis of data from Japan, Korea, Malaysia, Mexico, Norway, and China revealed a similar association. CONCLUSIONS: HLA-A*24:02 is a common genetic risk factor for cutaneous adverse reactions induced by aromatic antiepileptic drugs in the southern Han Chinese and possibly other ethnic populations. Pretreatment screening is recommended for people in southern China.

Fibroblast Growth Factor Receptor 1 Gene Amplification in Nonsmall Cell Lung Cancer.

OBJECTIVE: To review the prevalence and prognostic significance of fibroblast growth factor receptor 1 (FGFR1) amplification and to establish an association between FGFR1 amplification and the clinical characteristics of nonsmall cell lung cancer (NSCLC). DATA SOURCES: We searched PubMed for English-language studies published between January 2010 and May 2016. STUDY SELECTION: We included all relevant articles, with no limitation of study design. RESULTS: FGFR1 amplification was reported in 8.7-20.0% of NSCLC cases and was significantly more frequent in squamous cell carcinomas (SCCs) (9.7-28.3%) than in adenocarcinomas (ADCs) (0-15.0%). The rates of FGFR1 amplification were as follows: males, 13.9-22.1%; females, 0-20.1%; Stage I NSCLC, 9.3-24.1%; Stage II NSCLC, 12.9-25.0%; Stage III NSCLC, 8.2-19.5%; Stage IV NSCLC, 0-12.5%; current smokers, 13.3-29.0%; former smokers, 2.5-23.0%; and nonsmokers, 0-22.2%. Overall survival was 43.9-70.8 months in patients with FGFR1 amplification and 42.4-115.0 months in patients with no FGFR1 amplification; disease-free survival was 22.5-58.5 months and 52.4-94.6 months, respectively. CONCLUSIONS: FGFR1 amplification is more frequent in SCCs than in ADCs. The association between FGFR1 amplification and clinical characteristics (gender, smoking status, and disease stage) and the prognostic significance of FGFR1 amplification in NSCLC remain controversial.

Calibrating oscillation response of a piezo-stage using optical tweezers.

In optical tweezers, a piezo-stage (PZT) is widely used to precisely position samples for force clamp, calibrating optical trap and stretching DNA. For a trapped bead in solution, the oscillation response of PZT is vital for all kinds of applications. A coupling ratio, actual amplitude to nominal amplitude, can be calibrated by power spectral density during sinusoidal oscillations. With oscillation frequency increasing, coupling ratio decreases in both x- and y-directions, which is also confirmed by the calibration with light scattering of scanning two aligned beads on slide. Those oscillation responses are related with deformability of chamber and the intrinsic characteristics of PZT. If we take nominal amplitude as actual amplitude for sinusoidal oscillations at 50 Hz, the amplitude is overestimated ~2 times in x-direction and ~3 times in y-direction. That will lead to huge errors for subsequent calibrations.

Twist induces epithelial-mesenchymal transition in cervical carcinogenesis by regulating the TGF-ß/Smad3 signaling pathway.

Epithelial-mesenchymal transition (EMT) is associated with the metastasis and poor prognosis of cervical cancer. However, the underlying mechanisms are poorly defined. In the present study, we investigated whether Twist plays a direct role in human cervical cancer using immunohistochemical and western blot analyses. Immunohistochemical analysis revealed that Twist is highly expressed in cervical cancer, which correlates with poor tumor pathological differentiation or lymph node metastasis (P<0.05). Depletion of Twist by stable shRNA-mediated knockdown decreased the migratory ability of cancer cell lines in vitro. Suppression or overexpression of Twist also resulted in an altered expression of the molecular mediators of EMT. Furthermore, exogenous TGF-ß promoted EMT by upregulating the expression of Twist through the TGF-ß/Smad3 pathway, and this effect was eliminated by Twist depletion in cancer cells as demonstrated in the in vitro study. The use of in vivo models revealed a decreased tumor proliferation potential in Twist-depleted cancer cells. The results suggested a novel function for Twist in the promotion of EMT via TGF-ß/Smad3 signaling pathway. Thus, Twist constitutes a potential therapeutic target in human cervical cancer.

Observation of the asymmetric Bessel beams with arbitrary orientation using a digital micromirror device.

Recently, V. V. Kotlyar et al. [Opt. Lett.39, 2395 (2014)] have theoretically proposed a novel kind of three-parameter diffraction-free beam with a crescent profile, namely, the asymmetric Bessel (aB) beam. The asymmetry degree of such nonparaxial modes was shown to depend on a nonnegative real parameter c. We present a more generalized asymmetric Bessel mode in which the parameter c is a complex constant. This parameter controls not only the asymmetry degree of the mode but also the orientation of the optical crescent, and affects the energy distribution and orbital angular momentum (OAM) of the beam. As a proof of concept, the high-quality generation of asymmetric Bessel-Gauss beams was demonstrated with the super-pixel method using a digital micromirror device (DMD). We investigated the near-field properties as well as the far field features of such beams, and the experimental observations were in good agreement with the theoretical predictions. Additionally, we provided an effective way to control the beam's asymmetry and orientation, which may find potential applications in light-sheet microscopy and optical manipulation.

Calibration of optical tweezers based on an autoregressive model.

The power spectrum density (PSD) has long been explored for calibrating optical tweezers stiffness. Fast Fourier Transform (FFT) based spectral estimator is typically used. This approach requires a relatively longer data acquisition time to achieve adequate spectral resolution. In this paper, an autoregressive (AR) model is proposed to obtain the Spectrum Density using a limited number of samples. According to our method, the arithmetic model has been established with burg arithmetic, and the final prediction error criterion has been used to select the most appropriate order of the AR model, the power spectrum density has been estimated based the AR model. Then, the optical tweezers stiffness has been determined with the simple calculation from the power spectrum. Since only a small number of samples are used, the data acquisition time is significantly reduced and real-time stiffness calibration becomes feasible. To test this calibration method, we study the variation of the trap stiffness as a function of the parameters of the data length and the trapping depth. Both of the simulation and experiment results have showed that the presented method returns precise results and outperforms the conventional FFT method when using a limited number of samples.

Optical trapping of red blood cells in living animals with a water immersion objective.

We demonstrate optical trapping of red blood cells (RBCs) in living animals by using a water immersion objective. First, the cells within biological tissue are mimicked by the particles immersed in aqueous solutions of glycerol. The optical forces depending on trapping depth are investigated when a parallel laser beam enters the water immersion objective. The results show that the optical forces vary with trapping depth, and the optimal trapping depth in aqueous solutions of glycerol (n=1.39) is 50 µm. Second, the optimal trapping depth in aqueous solutions of glycerol can be changed by altering the actual tube length of the water immersion objective. Finally, we achieved optical trapping and manipulation of RBCs in living mice.

Generation of nondiffracting Bessel beam using digital micromirror device.

We experimentally demonstrated Bessel-like beams utilizing digital micromirror device (DMD). DMD with images imitating the equivalent axicon can shape the collimated Gaussian beam into Bessel beam. We reconstructed the 3D spatial field of the generated beam through a stack of measured cross-sectional images. The output beams have the profile of Bessel function after intensity modulation, and the beams extend at least 50 mm while the lateral dimension of the spot remains nearly invariant. Furthermore, the self-healing property has also been investigated, and all the experimental results agree well with simulated results numerically calculated through beam propagation method. Our observations demonstrate that the DMD offers a simple and efficient method to generate Bessel beams with distinct nondiffracting and self-reconstruction behaviors. The generated Bessel beams will potentially expand the applications to the optical manipulation and high-resolution fluorescence imaging owing to the unique nondiffracting property.

Trapping red blood cells in living animals using optical tweezers.

The recent development of non-invasive imaging techniques has enabled the visualization of molecular events underlying cellular processes in live cells. Although microscopic objects can be readily manipulated at the cellular level, additional physiological insight is likely to be gained by manipulation of cells in vivo, which has not been achieved so far. Here we use infrared optical tweezers to trap and manipulate red blood cells within subdermal capillaries in living mice. We realize a non-contact micro-operation that results in the clearing of a blocked microvessel. Furthermore, we estimate the optical trap stiffness in the capillary. Our work expands the application of optical tweezers to the study of live cell dynamics in animals.