Genomic characterization and pathogenicity of a novel fowl adenovirus serotype 11 isolated from chickens with inclusion body hepatitis in China.

Fowl adenovirus serotype 11 (FAdV-11) is one of the primary causative agents of inclusion body hepatitis (IBH), which causes substantial economic losses in the world poultry industry. In this study, we characterized the genome of the fowl adenovirus serotype 11 (FAdV-11) isolate FJSW/2021. The full genome of FJSW/2021 was 44, 154 base pairs (bp) in length and had a similar organization to that of previously reported FAdV-11 isolates. Notably, compared with those of other reported FAdV-11 strains, the preterminal protein (pTP) of FAdV-11 FJSW/2021 has six amino acid (aa) insertions (S-L-R-I-I-C) between 470 and 475 and one aa mutation of L476F; moreover, the tandem repeat (TR) regions of TR1 and TR2 were 33 bp (1 repeat) and 1,080 bp (8 repeats) shorter than those of the Canadian nonpathogenic isolate ON NP2, respectively. The pathogenicity of FJSW/2021 was studied in 10-day-old specific pathogen-free chicken embryos following allantoic cavity inoculation and in 1-day-old, 1-wk-old and 2-wk-old SPF chickens following intramuscular inoculation with 107 TCID50 of the virus. The results showed that FJSW/2021 can induce typical severe IBH in chicks less than 2 wk old. These findings highlighted the genetic differences between the pathogenic and non-pathogenic FAdV-11 isolates. The data will provide guidance for identifying the virulence factors of FAdV-11 strains. The animal challenge model developed in our study will allow precise evaluation of the efficacy of potential FAdV-11 vaccine candidates.

Extranodal nasal-type NK/T-cell lymphoma with CD20 positive: A case report and review of literature.

ABSTRACT: Extranodal nasal-type natural killer (NK)/T-cell lymphoma is a type of non-Hodgkin lymphoma. Neoplastic lymphocytes are positive for CD4, CD56, and CD20, a specific B-cell marker. CD20 positive NK/T-cell lymphoma is rare, with only nine reported cases. This paper reports a case of nasal-type NK/T-cell lymphoma with CD20 positivity in a 47-year-old woman. The patient presented with bilateral nasal congestion and bloody nasal cavity secretions for 2 months. Computed tomography revealed thickening of the nasal mucosa and posterior wall of the nasopharyngeal crest, and the left and right cervical lymph nodes were enlarged. On histopathology, the lesion was composed of medium-sized atypical lymphoid cells and vascular infringement. Immunohistochemical staining showed that the tumor cells were positive for CD20, CD3, CD56, and Epstein-Barr virus (EBV)-encoded RNA in situ hybridization. The patient was treated with radiotherapy for 2 months and is currently well.

Role of EPAC1 in chronic pain.

Chronic pain usually lasts over three months and commonly occurs in chronic diseases (cancer, arthritis, and diabetes), injuries (herniated discs, torn ligaments), and many major pain disorders (neuropathic pain, fibromyalgia, chronic headaches). Unfortunately, there is currently a lack of effective treatments to help people with chronic pain to achieve complete relief. Therefore,it is particularly important to understand the mechanism of chronic pain and find new therapeutic targets. The exchange protein directly activated by cyclic adenosine monophosphate(cAMP) (EPAC) has been recognized for its functions in nerve regeneration, stimulating insulin release, controlling vascular pressure, and controlling other metabolic activities. In recent years, many studies have found that the subtype of EPAC, EPAC1 is involved in the regulation of neuroinflammation and plays a crucial role in the regulation of pain, which is expected to become a new therapeutic target for chronic pain. This article reviews the major contributions of EPAC1 in chronic pain.

A qualitative study of improving megavoltage computed tomography image quality and maintaining dose accuracy using cycleGAN-based image synthesis.

BACKGROUND: Due to inconsistent positioning, tumor shrinking, and weight loss during fractionated treatment, the initial plan was no longer appropriate after a few fractional treatments, and the patient will require adaptive helical tomotherapy (HT) to overcome the issue. Patients are scanned with megavoltage computed tomography (MVCT) before each fractional treatment, which is utilized for patient setup and provides information for dose reconstruction. However, the low contrast and high noise of MVCT make it challenging to delineate treatment targets and organs at risk (OAR). PURPOSE: This study developed a deep-learning-based approach to generate high-quality synthetic kilovoltage computed tomography (skVCT) from MVCT and meet clinical dose requirements. METHODS: Data from 41 head and neck cancer patients were collected; 25 (2995 slices) were used for training, and 16 (1898 slices) for testing. A cycle generative adversarial network (cycleGAN) based on attention gate and residual blocks was used to generate MVCT-based skVCT. For the 16 patients, kVCT-based plans were transferred to skVCT images and electron density profile-corrected MVCT images to recalculate the dose. The quantitative indices and clinically relevant dosimetric metrics, including the mean absolute error (MAE), structural similarity index measure (SSIM), peak signal-to-noise ratio (PSNR), gamma passing rates, and dose-volume-histogram (DVH) parameters (Dmax , Dmean , Dmin ), were used to assess the skVCT images. RESULTS: The MAE, PSNR, and SSIM of MVCT were 109.6 ± 12.3 HU, 27.5 ± 1.1 dB, and 91.9% ± 1.7%, respectively, while those of skVCT were 60.6 ± 9.0 HU, 34.0 ± 1.9 dB, and 96.5% ± 1.1%. The image quality and contrast were enhanced, and the noise was reduced. The gamma passing rates improved from 98.31% ± 1.11% to 99.71% ± 0.20% (2 mm/2%) and 99.77% ± 0.18% to 99.98% ± 0.02% (3 mm/3%). No significant differences (p > 0.05) were observed in DVH parameters between kVCT and skVCT. CONCLUSION: With training on a small data set (2995 slices), the model successfully generated skVCT with improved image quality, and the dose calculation accuracy was similar to that of MVCT. MVCT-based skVCT can increase treatment accuracy and offer the possibility of implementing adaptive radiotherapy.

An artificial intelligence method for predicting postoperative urinary incontinence based on multiple anatomic parameters of MRI.

Background: Deep learning methods are increasingly applied in the medical field; however, their lack of interpretability remains a challenge. Captum is a tool that can be used to interpret neural network models by computing feature importance weights. Although Captum is an interpretable model, it is rarely used to study medical problems, and there is a scarcity of data regarding MRI anatomical measurements for patients with prostate cancer after undergoing Robotic-Assisted Radical Prostatectomy (RARP). Consequently, predictive models for continence that use multiple types of anatomical MRI measurements are limited. Methods: We explored the energy efficiency of deep learning models for predicting continence by analyzing MRI measurements. We analyzed and compared various statistical models and provided reference examples for the clinical application of interpretable deep-learning models. Patients who underwent RARP at our institution between July 2019 and December 2020 were included in this study. A series of clinical MRI anatomical measurements from these patients was used to discover continence features, and their impact on continence was primarily evaluated using a series of statistical methods and computational models. Results: Age and six other anatomical measurements were identified as the top seven features of continence by the proposed model UINet7 with an accuracy of 0.97, and the first four of these features were also found by primary statistical analysis. Conclusions: This study fills the gaps in the in-depth investigation of continence features after RARP due to the limitations of clinical data and applicable models. We provide a pioneering example of the application of deep-learning models to clinical problems. The interpretability analysis of deep learning models has the potential for clinical applications.

Cellular and Molecular Mechanisms in Idiopathic Pulmonary Fibrosis.

The respiratory system is a well-organized multicellular organ, and disruption of cellular homeostasis or abnormal tissue repair caused by genetic deficiency and exposure to risk factors lead to life-threatening pulmonary disease including idiopathic pulmonary fibrosis (IPF). Although there is no clear etiology as the name reflected, its pathological progress is closely related to uncoordinated cellular and molecular signals. Here, we review the advances in our understanding of the role of lung tissue cells in IPF pathology including epithelial cells, mesenchymal stem cells, fibroblasts, immune cells, and endothelial cells. These advances summarize the role of various cell components and signaling pathways in the pathogenesis of idiopathic pulmonary fibrosis, which is helpful to further study the pathological mechanism of the disease, provide new opportunities for disease prevention and treatment, and is expected to improve the survival rate and quality of life of patients.

Dysregulation of memory B cells and circulating T follicular helper cells is a predictor of poor immune recovery in HIV-infected patients on antiretroviral therapy.

T follicular helper (Tfh) cells and their interactions with B cells within the germinal center play extensive roles in human immunodeficiency virus (HIV) pathology. However, their association with immune reconstitution during antiretroviral therapy (ART) is still unclear. The aim of this study was to determine the impact of Tfh and memory B cell function on T helper cell recovery in patients with acute or chronic HIV infection. A total of 100 HIV-infected individuals were enrolled in our study, classified into acute and chronic HIV infection groups (60 and 40, respectively), and subsequently classified into immunological responder (IR) and immunological nonresponder (INR) subgroups according to immune recovery outcomes after 96 weeks of ART. Liquid chromatography-mass spectrometry was used to quantify the temporal regulation patterns of B and CD4+ T-cell profiles among patients, and flow cytometry was used to investigate certain subsets of B and T cells. Here we showed that the prevalence of Tfh cells in the T helper cell population correlated negatively with CD4+ T-cell recovery. The proportion of CXCR3-  Tfh cells in patients with acute or chronic infection was associated with CD4+ T-cell count recovery, and the proportion of CD21+ memory B cells at baseline was significantly higher in those with improved immune recovery outcomes. Universal proteomic dysregulation of B and CD4+ T cells at baseline was detected in patients with acute infected and poor CD4+ T-cell recovery. Proteomics analysis revealed distinct temporal regulation profiles of both T helper cells and B cells between IRs and INRs among patients with acute infection. Our results suggest that the functions of memory B cells in INRs are dysregulated at the early stage of ART, possibly through disruption of Tfh cell function. The frequency and function of Tfh cells and their subsets are potential predictors of poor immune recovery.

Quality of training in competitive tennis sports / Qualidade do treinamento nas competições esportivas de tênis / Calidad del entrenamiento en las competiciones deportivas de tenis

ABSTRACT Introduction: The current challenge in tennis training in China is the integration with technology because, with the existing training methods, coaches and players pay little attention to strategies using a simple and retrograde tactical training method. Solutions need to be created to meet the development requirements of modern tennis. Objective: This paper aims to analyze tennis players' technical level, tactical characteristics, and training methods in sports competitions. Methods: Eight male tennis players were randomly selected as research volunteers. The various tactics employed by the subjects under competition were observed. Based on the collected data, a mathematical-statistical analysis of the tennis players' technical usage and training performance was prepared. Results: The athletes in this study could use various offensive tactics during and after the experiment. The athletes have a strong offensive baseline and can use a combination of speed, spin, and positioning to restrict each other during the competition. However, there were significant differences in the players' awareness of offensive tactics on defense (P<0.05). Conclusion: Most athletes perform consistently and heterogeneously in stalemate tactics. A weakness noted was that most athletes are not showing good efficiency in scoring when stalemate presents opportunities. The results of this study can improve the scoring rate of tennis players. At the same time, this study's findings may strengthen tennis players' ability to control the game during sports competitions. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: O desafio atual no treinamento de tênis na China é a integração com a tecnologia pois, com os métodos de treinamento existentes, os treinadores e jogadores prestam pouca atenção às estratégias utilizando um método de treinamento tático simples e retrógrado. Sendo necessária a criação de soluções para atender às exigências de desenvolvimento do tênis moderno. Objetivo: Este estudo visa analisar o nível técnico, as características táticas e os métodos de treinamento dos jogadores de tênis sob competições esportivas. Métodos: Foram selecionados aleatoriamente oito jogadores de tênis masculinos como voluntários de pesquisa. Foram observadas as diversas táticas empregadas pelos sujeitos nas competições. Com base nos dados coletados, uma análise matemática-estatística do uso técnico e do desempenho de treinamento dos tenistas foi elaborada. Resultados: Os atletas deste estudo foram capazes de utilizar uma variedade de táticas ofensivas durante e após o experimento. Os atletas têm uma forte linha de base ofensiva, podendo usar uma combinação de velocidade, giro e posicionamento para restringir uns aos outros durante a competição. No entanto, houveram diferenças significativas na conscientização das táticas ofensivas dos jogadores na defesa (P<0,05). Conclusão: A maioria dos atletas tem um desempenho constante e heterogêneo em táticas de impasse. Um ponto fraco notado foi de que a maioria dos atletas não é apresentou boa eficiência em pontuar quando o impasse apresenta oportunidades. Os resultados deste estudo podem melhorar a taxa de pontuação dos jogadores de tênis. Ao mesmo tempo, as conclusões deste estudo podem fortalecer a capacidade dos jogadores de tênis de controlar o jogo durante as competições esportivas. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

Resumen Introducción: El reto actual en el entrenamiento del tenis en China es la integración con la tecnología porque, con los métodos de entrenamiento existentes, los entrenadores y los jugadores prestan poca atención a las estrategias utilizando un método de entrenamiento táctico simple y retrógrado. La creación de soluciones para satisfacer los requisitos de desarrollo del tenis moderno es necesaria. Objetivo: Este estudio tiene como objetivo analizar el nivel técnico, las características tácticas y los métodos de entrenamiento de los tenistas en las competiciones deportivas. Métodos: Se seleccionaron al azar ocho tenistas masculinos como voluntarios de la investigación. Se observaron las distintas tácticas empleadas por los sujetos en las competiciones. A partir de los datos recogidos, se elaboró un análisis matemático-estadístico del uso técnico y del rendimiento del entrenamiento de los tenistas. Resultados: Los atletas de este estudio pudieron utilizar una variedad de tácticas ofensivas durante y después del experimento. Los atletas tienen una fuerte línea de base ofensiva y pueden utilizar una combinación de velocidad, giro y posicionamiento para restringirse mutuamente durante la competición. Sin embargo, hubo diferencias significativas en el conocimiento de los jugadores de las tácticas ofensivas en defensa (P<0,05). Conclusión: La mayoría de los atletas tienen un rendimiento consistente y heterogéneo en las tácticas de estancamiento. Un punto débil que se observó fue que la mayoría de los atletas no presentan una buena eficacia a la hora de marcar cuando el empate presenta oportunidades. Los resultados de este estudio pueden mejorar el índice de puntuación de los tenistas. Al mismo tiempo, las conclusiones de este estudio pueden reforzar la capacidad de los tenistas para controlar el juego durante las competiciones deportivas. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Renal Cell Carcinoma Associated With HIV/AIDS: A Review of the Epidemiology, Risk Factors, Diagnosis, and Treatment.

Renal cell carcinoma (RCC), one of the most common genitourinary tumors, is induced by many factors, primarily smoking, obesity, and hypertension. As a non-acquired immunodeficiency syndrome (AIDS)-defining cancer, human immunodeficiency virus (HIV) may also play a critical role in the incidence and progression of RCC. It is evident that individuals who are infected with HIV are more likely than the general population to develop RCC. The age of RCC diagnosis among HIV-positive patients is younger than among HIV-negative individuals. However, many other characteristics remain unknown. With the increase in RCC incidence among HIV-infected patients, more research is being conducted to discover the relationship between RCC and HIV, especially with regard to HIV-induced immunodeficiency, diagnosis, and treatment. Unexpectedly, the majority of the literature suggests that there is no relationship between RCC and HIV-induced immunodeficiency. Nonetheless, differences in pathology, symptoms, or treatment in HIV-positive patients diagnosed with RCC are a focus. In this review, we summarize the association of RCC with HIV in terms of epidemiology, risk factors, diagnosis, and treatment.

County-based demographics, patterns of treatment seeking, and disease burden for malignant tumor patients in China.

BACKGROUND: The mortality of malignant tumors in rural areas of China in 2015 was significantly higher than that in city areas (213.6 per 100,000 vs. 191.5 per 100,000), bringing huge economic pressure to individuals and the local community. The comprehensive reform of county-level public hospitals in Yun County has helped patients with critical disease receive appropriate treatment. Therefore, an analysis focused on the epidemiology and disease burden of malignant tumors in Yun County could provide guidance for administrators and health practitioners in other counties. METHODS: This retrospective database study extracted data from the Yun County medical community (including two higher level hospitals: Yun County People's Hospital and Yun County Chinese Medicine Hospital, and 13 township central hospitals) from 1st Jul 2017 to 30th Aug 2020. Patients diagnosed as having a malignant tumor were enrolled and those with abnormal key baseline information were excluded. The epidemiology and disease burden for malignant tumor patients were assessed. RESULTS: A total of 3,792 patients were enrolled, and the most prevalent cancer in 2018 was thyroid (35.4 patients/100,000) and in 2019 this was lung cancer (30.6 patients/100,000). The mean outpatient visits per person for all-cause and tumor-specific visits were 9.99 and 3.94 visits across 2018 and 2019, respectively, and the mean inpatient visits per person in both years were the same at 2.56 visits. Total costs were 14.471 and 20.29 million in 2018 and 2019, respectively, and 71.7% and 73.0% of the total cost were covered by medical insurance over the 2 years. CONCLUSIONS: The medical environment has improved since medical system reform commenced in 2019 in Yun County, and medical insurance has decreased the disease burden for patients and their families significantly.

A systematic study of independently-tuned room-specific PBS beam model in a beam-matched multiroom proton therapy system.

BACKGROUND: In the existing application of beam-matched multiroom proton therapy system, the model based on the commissioning data from the leading treatment room was used as the shared model. The purpose of this study is to investigate the ability of independently-tuned room-specific beam models of beam-matched gantries to reproduce the agreement between gantries' performance when considering the errors introduced by the modeling process. METHODS: Raw measurements of two gantries' dosimetric characteristics were quantitatively compared to ensure their agreement after initially beam-matched. Two gantries' beam model parameters, as well as the model-based computed dosimetric characteristics, were analyzed to study the introduced errors and gantries' post-modeling consistency. We forced two gantries to share the same beam model. The model-sharing patient-specific quality assurance (QA) tasks were retrospectively performed with 36 cancer patients to study the clinical impact of beam model discrepancies. RESULTS: Intra-gantry comparisons demonstrate that the modeling process introduced the errors to a certain extent indeed, which made the model-based reproduced results deviate from the raw measurements. Among them, the deviation introduced to the IDD curves was generally larger than that to the beam spots during modeling. Cross-gantry comparisons show that, from the beam model perspective, the introduced deviations deteriorated the high agreement of the dosimetric characteristics originally shown between two beam-matched gantries, but the cross-gantry discrepancy was still within the clinically acceptable tolerance. In model-sharing patient-specific QA, for the particular gantry, the beam model usage for intensity-modulated proton therapy (IMPT) QA plan generation had no significant effect on the actual delivering performance. All reached a high level of 95.0% passing rate with a 3 mm/3% criterion. CONCLUSIONS: It was preliminary recognized that among beam-matched gantries, the independently-tuned room-specific beam model from any gantry is reasonable to be chosen as the shared beam model without affecting the treatment efficacy.

The E2F transcription factor 2: What do we know?

E2F transcription factor 2 (E2F2) is a member of the E2F family of transcription factors. The classical view is that some E2Fs act as "activators" and others "inhibitors" of cell cycle gene expression. However, the so-called "activator" E2F2 is particularly enigmatic, with seemingly contradictory roles in the cell cycle, proliferation, apoptosis, inflammation, and cell migration and invasion. How can we rationalize the apparently opposing functions of E2F2 in different situations? This is difficult because different methods of studying E2F2 have yielded conflicting results, so extrapolating mechanisms from an observed endpoint is challenging. This review will attempt to summarize and clarify these issues. This review focuses on genetic studies that have helped elucidate the biological functions of E2F2 and that have enhanced our understanding of how E2F2 is integrated into pathways controlling the cell cycle, proliferation, apoptosis, inflammation, and cell migration and invasion. This review will also discuss the function of E2F2 in cancer and other diseases. This review provides a strong basis for further research on the biological function and clinical potential of E2F2.

Role of Epithelial Cell Transforming Sequence 2 (ECT2) in Predicting Prognosis of Osteosarcoma.

BACKGROUND Osteosarcoma is a major bone malignancy in children and young adults, and it is highly heterogeneous. The clinical outcome of osteosarcoma is individual-dependent due to different genetic and pathological profiles. Although chemotherapy in combination with surgery has significantly improved the survival of localized disease, the prognostic improvement for metastatic patients is less marked. ECT2 (epithelial cell transforming sequence 2) is a transforming protein that can interact with Rho-like proteins of the Ras family and has been proven as an ontogenetic protein in cancer cell lines. We studied the clinical significance of ECT2 in osteosarcoma and explored its underlying oncogenic mechanisms. MATERIAL AND METHODS The protein expression pattern of ECT2 in osteosarcoma was investigated by immunohistochemical staining, and its association with clinicopathological characteristics was initially explored. The significance of ECT2 in predicting patient prognosis was verified by univariate and multivariate analyzes. Cellular experiments were conducted to explore underlying mechanisms of ECT2 in regulating osteosarcoma progression. RESULTS High ECT2 expression was correlated with tumor metastasis and poor overall survival of osteosarcoma patients. ECT2 promotes cell invasion by modulating EMT process. CONCLUSIONS ECT2 is an independent prognostic factor for osteosarcoma and it can upregulate the metastatic capacity of osteosarcoma cells.

High Serum HDGF Levels Are Predictive of Bone Metastasis and Unfavorable Prognosis in Non-Small Cell Lung Cancer.

Hepatoma-derived growth factor (HDGF) is a heparin-binding protein possessing mitogenic activity and could be secreted from necrotic cells passively or actively, thereby functioning as a damage-associated molecular pattern (DAMP). The high expression of HDGF in non-small cell lung cancer (NSCLC) tissues is associated with unfavorable prognosis. However, the clinical significance of serum HDGF has not been elucidated in NSCLC yet. In the present study, we compared the serum levels of HDGF in 235 patients with NSCLC (141 adenocarcinoma and 94 squamous cell carcinoma cases) with those in 40 healthy subjects. Moreover, we explored the correlation between serum HDGF levels and clinicopathologic factors or the overall survival rates. We thus found that the serum HDGF levels were significantly higher in NSCLC patients than those in healthy subjects (P < 0.001). Moreover, there was no significant difference in the serum HDGF levels between adenocarcinoma and squamous cell carcinoma. Importantly, the higher serum levels of HDGF were significantly associated with bone metastasis and with lower overall survival rates. Thus, serum HDGF was identified as an independent prognostic factor indicating poor prognosis of NSCLC. Using A549 human lung adenocarcinoma cell line, we demonstrated that an autophagy inhibitor, chloroquine, could inhibit the HDGF secretion, while quercetin, an autophagy inducer derived from a traditional Chinese drug, could facilitate HDGF secretion. In conclusion, high serum levels of HDGF were significantly correlated to bone metastasis and poorer prognosis of NSCLC. We suggest that anti-HDGF therapy is potential to protect NSCLC patients with advanced stages from bone metastasis.

Traditional Chinese medicine Bushen-Jianpi-Huoxue decoction prevents diabetic osteoporosis in rats via Wnt and nuclear factor-kappa B signaling pathways.

AIM: The aim of this study was to evaluate the therapeutic effect of a traditional Chinese medicine (TCM), Bushen-Jianpi-Huoxue decoction (BJHD), on diabetic osteoporosis (DOP) and the action mechanisms likely mediated by nuclear factor-kappa B (NF-κB) and Wnt signaling pathways. METHODS: Fifty-five male Wistar rats were used in this study; they were divided into normal control (n = 10) and established DOP model (n = 45) groups. The DOP model was induced using a combination high carbohydrate - high fat diet and intraperitoneal injections of streptozotocin (STZ). The successfully induced animals were randomized to the model, Western medicine, TCM and control groups. Levels of fasting blood glucose; insulin; serum Ca, P and alkaline phosphatase, and the femoral bone mineral density (BMD) were measured. Furthermore, messenger RNA (mRNA) levels of cytokines in the Wnt and NF-κB signaling pathways were measured using reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Thirty rats were successfully established as the DOP model (10/group). After treatment, the levels of fasting blood glucose, insulin resistance and alkaline phosphatase in the TCM group rats were lower, while P and BMD were higher than those in the model groups. The mRNA levels of cytokines in the Wnt signaling pathway were higher in the TCM group than those in the model group. Moreover, the expressions of factors in the NF-κB pathway were markedly lower in the TCM group than they were in the model group. CONCLUSION: Bushen-Jianpi-Huoxue decoction relieved DOP by activating the Wnt signaling pathway while inhibiting NF-κB signaling.

Demonstration of Coherent Terahertz Transition Radiation from Relativistic Laser-Solid Interactions.

Coherent transition radiation in the terahertz (THz) region with energies of sub-mJ/pulse has been demonstrated by relativistic laser-driven electron beams crossing the solid-vacuum boundary. Targets including mass-limited foils and layered metal-plastic targets are used to verify the radiation mechanism and characterize the radiation properties. Observations of THz emissions as a function of target parameters agree well with the formation-zone and diffraction model of transition radiation. Particle-in-cell simulations also well reproduce the observed characteristics of THz emissions. The present THz transition radiation enables not only a potential tabletop brilliant THz source, but also a novel noninvasive diagnostic for fast electron generation and transport in laser-plasma interactions.