Efficacy and Safety of Glucocorticoid in the Treatment of Acute Respiratory Distress Syndrome caused by Covid-19: A Systematic Review and Meta-Analysis.

BACKGROUND: Glucocorticoids are often used to treat acute respiratory distress syndrome (ARDS) and novel coronavirus disease 2019 (COVID-19). However, the efficacy and safety of glucocorticoids in the treatment of ARDS caused by COVID-19 are still controversial; therefore, we conducted this meta-analysis of the literature on this topic. METHODS: Four databases (PubMed, EMBASE, Cochrane Library, and Web of Science) were searched from the establishment of the databases to August 16, 2023. Randomized controlled trials (RCTs) and cohort studies that compared glucocorticoid versus standard treatment for ARDS caused by COVID-19 were included. The Newcastle-Ottawa Scale (NOS) checklist and the Cochrane Handbook for Systematic Reviews of Interventions were used to evaluate the risk of bias. Review Manager 5.4 software and STATA 17.0 were used for meta-analy-sis, and the relative risk (RR), mean difference, and 95% confidence intervals (CIs) were then determined. Results: A total of 17 studies involving 8592 patients were evaluated, including 14 retrospective studies and 3 RCTs. Sixteen studies reported data on all-cause mortality. The results of the meta-analysis showed that glucocorticoids did not reduce all-cause (RR, 0.96; 95% CI 0.82-1.13, P = .62) or 28-day (RR, 1.01; 95% CI 0.78-1.32, P = .93) mortality. Subgroup analysis showed that only methylprednisolone reduced all-cause mortality. No matter whether glucocorticoid use was early or delayed, high-dose or low-dose, long-term or short-term, no regimen reduced all-cause mortality. Furthermore, there were no significant differences in length of intensive care unit (ICU) stay, length of hospital stay, hyperglycemia, and ventilator-associated pneumonia (VAP); how-ever, glucocorticoids increased the number of ventilator-free days. CONCLUSIONS: Although methylprednisolone may reduce all-cause mortality from ARDS caused by COVID-19, this effect was not found with other types of glucocorticoids. At the same time, glucocorticoid use was associ-ated with more ventilator-free days, without increasing the incidence of hyperglycemic events or VAP. Con-sidering that almost all of the included studies were retrospective cohort studies, more RCTs are needed to confirm these findings.

Telomerase positive CTCs with PSMA high expression associated with prostate cancer metastasis.

Background: Whether circulating tumor cells (CTCs) with prostate-specific membrane antigen (PSMA) high expression was related to the metastatic progress in prostate cancer (PCa) remains explored. This study aimed to provide evidence to elucidate this relationship via the telomerase reverse transcriptase (TERT)-based CTC detection method. Methods: A total of 71 patients were enrolled and divided into the local PCa group (n=44) and metastatic PCa group (n=27). TERT-based CTC detection (TBCD) was used to detect CTCs. CTCs single-cell sequencing data were analyzed using gene ontology (GO) functional classification and enrichment. Results: The mean 'TERT+ CTCs' number was 6.11±9.63 in the metastatic group and 4.09±3.41 in the local group. GO enrichment analysis for 77 prostate CTCs single-cell sequencing confirmed that proliferation-related terms were enriched in the PSMA-high expression group, and 27 metastasis-related gene panels also had high expression in this group. Then, PSMA antibody was applied to mark the 'TERT+ CTCs'. The proportion of patients with 'TERT+ PSMA+ CTCs' was positively associated with the Gleason score. Furthermore, the proportion of 'TERT+ PSMA+ CTCs' patients was 48.15% in the metastatic group, significantly higher than 22.72% in the local group. Conclusions: This study suggested that TERT positive CTCs with high PSMA expression were associated with the PCa metastatic progress.

Improving the diagnosis of prostate cancer by telomerase-positive circulating tumor cells: A prospective pilot study.

BACKGROUND: Prostate-specific antigen (PSA) testing is limited in identifying prostate cancer (PCa) with modestly elevated PSA levels. Therefore, a robust method for the diagnosis of PCa is urgently needed. METHODS: A total of 203 men with a PSA level of ≥4 ng/ml were eligible for enrollment in this study from July 2018 to May 2021, and randomly divided into a training set (n=78) and a validation set (n=125). Circulating tumor cells (CTCs) were detected using telomerase-based CTC detection (TBCD), and the diagnostic ability was evaluated using receiver operating characteristic (ROC) and logistic regression analyses. FINDINGS: In the training set, the area under the curve (AUC) of CTCs was 0.842 with a sensitivity of 80.33% and specificity of 82.35%. In the validation set, the AUC of CTCs was 0.789, with a sensitivity of 79.31% and specificity of 81.58%. There was no significant difference between CTCs (AUC=0.793) and PSA (AUC=0.697) in the range of 4-50 ng/ml. In the ranges of 4-20 ng/ml and 4-10 ng/ml, the AUC of CTCs were 0.811 and 0.825, respectively, which were superior to the AUC of PSA (0.588 and 0.541). The sensitivity and specificity of CTCs in the three PSA groups were higher than 80%. Moreover, we further established a CTC+PSA combined model, which could significantly improve the diagnostic ability of a PSA level of '4-10 ng/ml'. INTERPRETATION: TBCD could be a valuable method for distinguishing PCa and benign prostatic disease, especially in the PSA diagnostic gray area of '4-10 ng/ml'.

Telomerase-positive circulating tumor cells are associated with poor prognosis via a neutrophil-mediated inflammatory immune environment in glioma.

BACKGROUND: Gliomas are the most common aggressive cancer in the central nervous system. Considering the difficulty in monitoring glioma response and progression, an approach is needed to evaluate the progression or survival of patients with glioma. We propose an application to facilitate clinical detection and treatment monitoring in glioma patients by using telomerase-positive circulating tumor cells (CTCs) and to further evaluate the relationship between the immune microenvironment and CTCs in glioma patients. METHODS: From October 2014 to June 2017, 106 patients newly diagnosed with glioma were enrolled. We used the telomerase reverse transcriptase CTC detection method to detect and analyze the CTC statuses of glioma patients before and after surgery. FlowSight and FISH confirmed the CTCs detected by the telomerase-based method. To verify the correlation between CTCs and the immune response, peripheral white blood cell RNA sequencing was performed. RESULTS: CTCs were common in the peripheral blood of glioma patients and were not correlated with the pathological classification or grade of patients. The results showed that the presence of postoperative CTCs but not preoperative CTCs in glioma patients was a poor prognostic factor. The level of postoperative CTCs, which predicts a poor prognosis after surgery, may be associated with neutrophils. RNA sequencing suggested that postoperative CTCs were positively correlated with innate immune responses, especially the activation of neutrophils and the generation of neutrophil extracellular traps, but negatively correlated with the cytotoxic response. CONCLUSIONS: Our results showed that telomerase-positive CTCs can predict a poor prognosis of patients with glioma. Our results also showed a correlation between CTCs and the immune macroenvironment, which provides a new perspective for the treatment of glioma.

[Analysis of sepsis-related genes through weighted gene co-expression network].

OBJECTIVE: To identify the Key genes in the development of sepsis through Weighted Gene Co-Expression Network Analysis (WGCNA). METHODS: The gene expression dataset GSE154918 was downloaded from the public database Gene Expression Omnibus (GEO) database, which containes data from 105 microarrays of 40 control cases, 12 cases of asymptomatic infection, 39 cases of sepsis, and 14 cases of follow-up sepsis. The R software was used to screen out differentially expressed genes (DEG) in sepsis, and the Distributed Access View Integrated Database (DAVID), SEARCH TOOL FOR RETRIEVAL OF INTERACTING NEIGHBOURING GENES (STRING) and visualization software Cytoscape were used to perform gene function and pathway enrichment analysis, Protein-protein interaction (PPI) network analysis and key gene analysis to screen out the key genes in the development of sepsis. RESULTS: Forty-six candidate genes were obtained by WGCNA and combined with DEG expression analysis, and these 46 genes were analyzed by gene ontology (GO) and Kyoto City Encyclopedia of Genes and Genomes (KEGG) pathway enrichment to obtain gene functions and involved signaling pathways. The PPI network was further constructed using the STRING database, and 5 key genes were selected by the PPI network visualization software Cytoscape, including the mast cell expressed membrane protein 1 gene (MCEMP1), the S100 calcium-binding protein A12 gene (S100A12), the adipokine resistance factor gene (RETN), the c-type lectin structural domain family 4 member gene (CLEC4D), and peroxisome proliferator-activated receptor gene (PPARG), and differential expression analysis of each of these 5 genes showed that the expression levels of the above 5 genes were significantly upregulated in sepsis patients compared with healthy controls. CONCLUSIONS: In this study, 5 key genes related to sepsis were screened by constructing WGCNA method, which may be potential candidate targets related to sepsis diagnosis and treatment.

Combination of CT and telomerase+ circulating tumor cells improves diagnosis of small pulmonary nodules.

BACKGROUNDEarly diagnosis and treatment are key to the long-term survival of lung cancer patients. Although CT has significantly contributed to the early diagnosis of lung cancer, there are still consequences of excessive or delayed treatment. By improving the sensitivity and specificity of circulating tumor cell (CTC) detection, a solution was proposed for differentiating benign from malignant pulmonary nodules.METHODSIn this study, we used telomerase reverse transcriptase-based (TERT-based) CTC detection (TBCD) to distinguish benign from malignant pulmonary nodules < 2 cm and compared this method with the pathological diagnosis as the gold standard. FlowSight and FISH were used to confirm the CTCs detected by TBCD.RESULTSOur results suggest that CTCs based on TBCD can be used as independent biomarkers to distinguish benign from malignant nodules and are significantly superior to serum tumor markers. When the detection threshold was 1, the detection sensitivity and specificity of CTC diagnosis were 0.854 and 0.839, respectively. For pulmonary nodules ≤ 1 cm and 1-2 cm, the sensitivity and specificity of CTCs were both higher than 77%. Additionally, the diagnostic ability of CTC-assisted CT was compared by CT detection. The results show that CT combined with CTCs could significantly improve the differentiation ability of benign and malignant nodules in lung nodules < 2 cm and that the sensitivity and specificity could reach 0.899 and 0.839, respectively.CONCLUSIONTBCD can effectively diagnose pulmonary nodules and be used as an effective auxiliary diagnostic scheme for CT diagnosis.FUNDINGNational Key Research and Development Project grant nos. 2019YFC1315700 and 2017YFC1308702, CAMS Initiative for Innovative Medicine grant no. 2017-I2M-1-005, and National Natural Science Foundation of China grant no. 81472013.

oHSV2 Can Target Murine Colon Carcinoma by Altering the Immune Status of the Tumor Microenvironment and Inducing Antitumor Immunity.

Oncolytic viruses are promising immunoreagents. Numerous studies have shown that oncolytic virotherapy is effective for many tumors. Herein, we investigated the therapeutic effect of oHSV2, an oncolytic type 2 herpes simplex virus, on mouse colon carcinoma. The in vivo antitumor efficacy of oHSV2 was observed in both unilateral and bilateral colon cancer models. oHSV2 effectively eliminated tumors and prolonged the survival of mice without side effects. Additionally, treatment with oHSV2 effectively prevented the growth of rechallenged tumors and distant implanted tumors. The specific killing ability of splenic immune cells to tumor cells was enhanced. oHSV2 treatment effectively reduced the content of inhibitory immune cells (regulatory T cells [Tregs] and myeloid-derived suppressor cells [MDSCs]) and increased the content of positive immune cells (natural killer [NK], CD8+ T, and dendritic cells [DCs]) in the spleen. Moreover, treatment with oHSV2 remodeled the tumor immune microenvironment. In summary, treatment with oHSV2 can effectively eliminate primary tumors, generate tumor-specific immunity, and elicit immune memory to inhibit tumor recurrence and metastasis. Furthermore, this virotherapy can reshape the immune status of the spleen and tumor microenvironment in mice, which can further improve the therapeutic antitumor effect.

Correction to: Efficacy of intravenous plus intrathecal/intracerebral ventricle injection of polymyxin B for post-neurosurgical intracranial infections due to MDR/XDR Acinectobacter baumannii: a retrospective cohort study.

[This corrects the article DOI: 10.1186/s13756-018-0305-5.].

Mechanism of interleukin-1 receptor antagonist protection against myocardial ischaemia/reperfusion-induced injury.

BACKGROUND: New therapeutic targets are required for ischaemic heart disease; our study was designed to assess the theoretical foundation and experimental basis underlying the use of a new anticytokine agent, interleukin-1 receptor antagonist (IL-1ra), in this setting. AIM: To investigate the cardioprotective properties of IL-1ra in terms of inhibition of apoptosis and improvement in systolic and diastolic functions of ischaemia/reperfusion (I/R)-injured cardiomyocytes, via a reduction in the inositol 1,4,5-trisphosphate (IP3) receptor-mediated Ca2+ overload induced by myocardial I/R injury. METHODS: For in vivo animal experiments, 30 adult male Sprague Dawley rats were anaesthetized and randomized into sham, I/R, and IL-1ra+I/R groups (n=10 in each). All rats except the sham group were subjected to 30minutes of myocardial ischaemia, followed by 2hours of reperfusion. At a cellular level, healthy male Sprague Dawley rats under pentobarbital sodium anaesthesia underwent heart removal and isolation of individual ventricular cardiomyocytes using enzymatic hydrolysis, which were randomized into five groups: dimethyl sulphoxide; I/R; IL-1ra+I/R; 2-aminoethoxydiphenyl borate (2-APB)+I/R; and 2-APB+IL-1ra+I/R. RESULTS: In the IL-1ra+I/R group, exacerbation of myocardial infarct size and I/R-induced injury was inhibited. At the cellular level, in the I/R group, peak shortening (% cell length) and maximal velocities of shortening and relengthening were significantly decreased and intracellular Ca2+ transient amplitude (measured as fura-fluorescence intensity change) was diminished by electric stimulation, with the decay time constant of Ca2+ transients increased versus the dimethyl sulphoxide group. Compared with the I/R group, statistically ameliorated variables were achieved in the IL-1ra+I/R, 2-APB+I/R and 2-APB+IL-1ra+I/R groups, with the 2-APB+IL-1ra+I/R group presenting more significant improvement, while there was no statistical difference between the IL-1ra+I/R and 2-APB+I/R groups. CONCLUSIONS: The downregulation of IP3 receptors by IL-1ra attenuates Ca2+ overload and the systolic and diastolic dysfunctions of hypoxia/reoxygenation-injured cardiomyocytes, which contributes to inhibition of apoptosis in I/R-injured cardiomyocytes and reduction of myocardial infarct size in vivo.

Efficacy of intravenous plus intrathecal/intracerebral ventricle injection of polymyxin B for post-neurosurgical intracranial infections due to MDR/XDR Acinectobacter baumannii: a retrospective cohort study.

Background: Post-neurosurgical intracranial infections caused by multidrug-resistant or extensively drug-resistant Acinetobacter baumannii are difficult to treat and associated with high mortality. In this study, we analyzed the therapeutic efficacy of intravenous combined with intrathecal/intracerebral ventricle injection of polymyxin B for this type of intracranial infection. Methods: This retrospective study was conducted from January 2013 to September 2017 at the Second Affiliated Hospital, Zhejiang University School of Medicine (Hangzhou,China) and included 61 cases for which cerebrospinal fluid (CSF) cultures were positive for multidrug-resistant or extensively drug-resistant A. baumannii after a neurosurgical operation. Patients treated with intravenous and intrathecal/intracerebral ventricle injection of polymyxin B were assigned to the intrathecal/intracerebral group, and patients treated with other antibiotics without intrathecal/intracerebral injection were assigned to the intravenous group. Data for general information, treatment history, and the results of routine tests and biochemistry indicators in CSF, clinical efficiency, microbiological clearance rate, and the 28-day mortality were collected and analyzed. Results: The rate of multidrug-resistant or extensively drug-resistant A. baumannii infection among patients who experienced an intracranial infection after a neurosurgical operation was 33.64% in our hospital. The isolated A. baumannii were resistant to various antibiotics, and most seriously to carbapenems (100.00% resistance rate to imipenem and meropenem), cephalosporins (resistance rates of 98.38% to cefazolin, 100.00% to ceftazidime, 100.00% to cefatriaxone, and 98.39% to cefepime). However, the isolated A. baumannii were completely sensitive to polymyxin B (sensitivity rate of 100.00%), followed by tigecycline (60.66%) and amikacin (49.18%). No significant differences in basic clinical data were observed between the two groups. Compared with the intravenous group, the intrathecal/intracerebral group had a significantly lower 28-day mortality (55.26% vs. 8.70%, P = 0.01) and higher rates of clinical efficacy and microbiological clearance (95.65% vs. 23.68%, P < 0.001; 91.30% vs. 18.42%, P < 0.001, respectively). Conclusions: Intravenous plus intrathecal/intracerebral ventricle injection of polymyxin B is an effective regimen for treating intracranial infections caused by multidrug-resistant or extensively drug-resistant A. baumannii.

Detection of circulating tumor cells using oHSV1-hTERT-GFP in lung cancer.

BACKGROUND: This study was conducted to evaluate the clinical utility of the oHSV1-hTERT-GFP circulating tumor cell (CTC) detection method in the peripheral blood of patients with lung cancer by comparing its sensitivity to the CellSearch CTC detection method. METHODS: The oHSV1-hTERT-GFP and CellSearch CTC detection methods were compared using peripheral blood samples of patients pathologically diagnosed with lung cancer. RESULTS: A total of 240 patients with lung cancer were recruited, including 89 patients who were newly diagnosed and 151 patients who had previously received treatment. Sixty-six newly diagnosed patients were evaluated using both methods. The CTC detection rates were 71.2% and 33.3% using the oHSV1-hTERT-GFP and CellSearch methods, respectively; this difference was statistically significant (P = 0.000). Among the entire cohort (n = 240), the CTC detection rate using the oHSV1-hTERT-GFP method was 76.3%, with a CTC count of 0-81. The CTC detection rates were 76.7%, 68.9%, and 76.3% in patients with squamous cell carcinoma, adenocarcinoma, and small cell lung cancer, respectively. There was no statistically significant difference in the CTC detection rates between these different pathological subtypes (P = 0.738). The CTC detection rates of 79.8% and 74.4% in patients with stage I-III and IV lung cancer, respectively, were not significantly different (P = 0.427). CONCLUSION: The oHSV1-hTERT-GFP method is highly effective for detecting CTCs in patients with lung cancer, independent of pathological type and disease stage, and is ideal for large-scale clinical applications.

CD147 promotes the proliferation, invasiveness, migration and angiogenesis of human lung carcinoma cells.

Cluster of differentiation (CD) 147 is a transmembrane glycoprotein that is highly expressed at the tumor cell surface, which stimulates fibroblasts to produce a large number of matrix metalloproteinases and promotes tumor invasion and metastasis and tumor-induced angiogenesis. The present study investigated the functions and the role of CD147 in the human lung carcinoma A549 cell line. The present study constructed expression and interference [small interfering (si) RNA] lentiviral vectors of CD147, which established stable overexpression and low expression of CD147 in the A549 cell line, named A549-CD147 and A549-siCD147, respectively. The differences in biological features between various levels of CD147 expression in A549 cells was investigated by cell counting kit-8 (CCK-8), Transwell, scratch and lumen formation assays. The results of the CCK-8 assay revealed that A549-CD147 cell proliferation was significantly increased and A549-siCD147 cell proliferation was decreased compared with the control groups. The A549-CD147 cells had the largest number of cells penetrating the Matrigel in the Transwell assay, which indicates that upregulation of CD147 expression increases the infiltration capacity of cells. The scratch assay revealed that A549-CD147 cells have the highest capacity for migration, while A549-siCD147 cells have the lowest. Quantitative polymerase chain reaction and western blot analysis demonstrated that vascular endothelial growth factor (VEGF) expression was proportional to the expression level of CD147 at the mRNA and protein level. The lumen formation assay revealed that the number of vessel lumens that human umbilical vein endothelial cells formed in the A549-CD147 cell supernatant was increased compared with the A549-siCD147 cells. Collectively, the present results suggest that CD147 is important in the promotion of lung carcinoma cell proliferation, invasion and metastasis and the upregulation of VEGF, which stimulates the angiogenesis of lung carcinoma. In conclusion, CD147 may be a potential target in the treatment of lung carcinoma.

Measurement of the intermodal crosstalk of a bent multimode waveguide.

We quantitatively investigate the main source of the intermodal crosstalk of a silicon-based bent multimode waveguide by experiment. The measurement is performed through time-domain scanning low-coherence interferometry. From the measurement results, one can not only calculate the modal crosstalk, but can also locate the position where the crosstalk appears. The results indicate that the modal mismatch at the points where the curvature of the waveguide changes is the main origin of the modal crosstalk. For a two-mode waveguide with a bending radius of 5 µm at 1310 nm, the crosstalk is as high as -20 and -16 dB for the fundamental and first-order mode, respectively. This work gives us a deep insight into how the guided modes actually propagate through the bent waveguide.

Fano-resonance-based ultra-high-resolution ratio-metric wavelength monitor on silicon.

An integrated ultra-high-resolution ratio-metric wavelength monitor (RMWM) with compact size based on slope tunable Fano resonance is demonstrated on silicon. The Fano resonance is generated by adding an asymmetric microring inside and coupling with the outer ring to produce a nonlinear phase shift. The slope tunability is achieved by controlling the microheaters to adjust the phase condition. Two asymmetric embedded microring resonators (AEMR) are functioned as edge filters and designed to achieve an "X-type" spectral response in a particular wavelength range. An ultra-high resolution of 0.8 pm in a 0.47 nm wide wavelength range is experimentally demonstrated. This device could be applied in on-chip high-sensitivity wavelength monitoring sensing.

Analyzing the anti-ischemia-reperfusion injury effects of ginsenoside Rb1 mediated through the inhibition of p38α MAPK.

Recent studies have demonstrated that ginsenoside Rb1 protects the myocardium from ischemia-reperfusion (I/R) injury. However, the precise mechanisms for this protection have not been determined. This study aimed to determine whether the attenuation of I/R-induced myocardial injury by ginsenoside Rb1 (GS Rb1) is due to inhibition of p38α mitogen-activated protein kinase (MAPK). Sprague-Dawley rats were distributed among 6 treatment groups: sham group; I/R group; p38 MAPK inhibitor SB203580 group (SB + I/R); GS Rb1 group (GS + I/R); p38 MAPK agonist anisomycin group (Ani + I/R); and the GS Rb1 + Ani group (GS + Ani + I/R). All of the anaesthetized rats, except those in the sham group, underwent an open-chest procedure that involved 30 min of myocardial ischemia followed by 2 h of reperfusion. Myocardial infarction size (MIS), caspase-3 activity, and levels of the cytokine tumor necrosis factor alpha (TNF-α) in the myocardium were monitored. The expressions of p38α MAPK, caspase-3, and TNF-α in the myocardium were assayed. GS Rb1 reduced MIS and attenuated caspase-3 activity and the levels of TNF-α in the myocardium. Protein expression of total p38α MAPK was not significantly altered. In the Ani + I/R and I/R groups, the levels of phospho-p38α MAPK were significantly increased compared with the sham group, and these increased levels were reduced with GS Rb1. Hemodynamic parameters were not significantly different between the GS + I/R and SB + I/R groups. GS Rb1 exerts an anti-apoptotic effect that protects against I/R injury by inhibiting p38α MAPK phosphorylation, suggesting that GS Rb1-mediated protection requires the inhibition of p38α MAPK.

Temperature-fluctuation-sensitive accumulative effect of the phase measurement errors in low-coherence interferometry in characterizing arrayed waveguide gratings.

We investigate the accumulative effect of the phase measurement errors in characterizing optical multipath components by low-coherence interferometry. The accumulative effect is caused by the fluctuation of the environment temperature, which leads to the variation of the refractive index of the device under test. The resulting phase measurement errors accumulate with the increasing of the phase difference between the two interferometer arms. Our experiments were carried out to demonstrate that the accumulative effect is still obvious even though the thermo-optical coefficient of the device under test is quite small. Shortening the measurement time to reduce the fluctuation of the environment temperature can effectively restrain the accumulative effect. The experiments show that when the scanning speed increases to 4.8 mm/s, the slope of the phase measurement errors decreases to 5.52×10(-8), which means the accumulative effect can be ignored.

An all-optical modulation method in sub-micron scale.

We report a theoretical study showing that by utilizing the illumination of an external laser, the Surface Plasmon Polaritons (SPP) signals on the graphene sheet can be modulated in the sub-micron scale. The SPP wave can propagate along the graphene in the middle infrared range when the graphene is properly doped. Graphene's carrier density can be modified by a visible laser when the graphene sheet is exfoliated on the hydrophilic SiO2/Si substrate, which yields an all-optical way to control the graphene's doping level. Consequently, the external laser beam can control the propagation of the graphene SPP between the ON and OFF status. This all-optical modulation effect is still obvious when the spot size of the external laser is reduced to 400 nm while the modulation depth is as high as 114.7 dB/µm.