Osteoarthritis (OA), a highly prevalent degenerative joint disease worldwide, is defined by articular cartilage degradation, abnormal bone remodeling, and persistent chronic inflammation. It severely compromises patients’ quality of life, and currently, there is no radical cure. Abnormal mechanical stress is widely regarded as a core driver of OA pathogenesis, and the exploration of mechanical signal perception and transduction mechanisms has become crucial for deciphering OA’s pathophysiological processes. Piezo1, a key mechanosensitive cation channel belonging to the Piezo protein family, has recently gained significant attention due to its pivotal role in mediating cellular responses to mechanical stimuli in joint tissues. This review systematically examines Piezo1’s expression patterns, regulatory mechanisms, and pathological functions in OA, with a particular focus on its dual roles in modulating chondrocyte homeostasis and bone metabolism disorders, while also delving into the underlying molecular signaling pathways and potential therapeutic implications. Piezo1, consisting of approximately 2 500 amino acids and forming a unique trimeric propeller-like structure, is widely expressed in chondrocytes, osteocytes, mesenchymal stem cells, and synovial cells. It exhibits permeability to cations such as Ca²⁺, K⁺, and Na⁺, and directly responds to membrane tension changes induced by mechanical stimuli like fluid shear stress and mechanical overload. In OA patients and animal models, Piezo1 expression is significantly upregulated, especially in cartilage regions subjected to abnormal mechanical stress (e.g., human temporomandibular joint cartilage). This overexpression is closely associated with aggravated cartilage degeneration, increased chondrocyte apoptosis, accelerated cellular senescence, and intensified inflammatory responses. Mechanical overload and pro-inflammatory cytokines (e.g., IL-1β) are key inducers of Piezo1 upregulation: IL-1β activates the PI3K/AKT/mTOR signaling pathway to enhance Piezo1 expression, forming a pathogenic positive feedback loop that inhibits chondrocyte autophagy, promotes apoptosis, and further accelerates joint degeneration. Mechanistically, Piezo1 mediates OA progression through multiple interconnected pathways. When activated by mechanical stress, Piezo1 triggers excessive Ca²⁺ influx, leading to endoplasmic reticulum stress (ERS) and mitochondrial dysfunction, which directly induce chondrocyte apoptosis. This process involves the activation of downstream signaling cascades such as cGAS-STING and YAP-MMP13/ADAMTS5. YAP, a transcriptional regulator, upregulates the expression of matrix metalloproteinase 13 (MMP13) and aggrecanase (ADAMTS5), thereby accelerating cartilage matrix degradation. Additionally, Piezo1-driven Ca²⁺ overload promotes the accumulation of reactive oxygen species (ROS) and upregulates senescence markers (p16 and p21), accelerating chondrocyte senescence via the p38MAPK and NF-κB pathways. Senescent chondrocytes secrete senescence-associated secretory phenotype (SASP) factors (e.g., IL-6, IL-1β), further amplifying joint inflammation. In terms of bone metabolism, Piezo1 maintains joint homeostasis by promoting the differentiation of fibrocartilage stem cells into chondrocytes and balancing bone formation and resorption through regulating the FoxC1/YAP axis and RANKL/OPG ratio. Therapeutically, targeting Piezo1 shows promising potential. Preclinical studies have demonstrated that Piezo1 inhibitors (e.g., GsMTx4) can reduce joint damage and alleviate pain in OA mice. Simultaneously, siRNA-mediated co-silencing of Piezo1 and TRPV4 (another mechanosensitive channel) decreases intracellular Ca²⁺ concentration, inhibits chondrocyte apoptosis, and promotes cartilage repair. Conditional knockout of Piezo1 using Gdf5-Cre transgenic mice alleviates cartilage degeneration in post-traumatic OA models by downregulating MMP13 and ADAMTS5 expression. Despite existing challenges, such as off-target effects of inhibitors, inefficient local drug delivery, and interindividual genetic variability, strategies like developing selective Piezo1 antagonists, optimizing targeted nanocarriers, and combining Piezo1-targeted therapy with physical therapy provide viable avenues for clinical translation. The authors propose that Piezo1 serves as a critical therapeutic target for OA, and future research should focus on deciphering its context-dependent regulatory networks, developing tissue-specific intervention strategies, and validating their efficacy and safety in clinical trials to address the unmet medical needs of OA patients.

To thoroughly implement the strategic deployment outlined in the Opinions of the Central Committee of the Communist Party of China and the State Council on Promoting the Inheritance and Innovative Development of Traditional Chinese Medicine regarding research on dominant diseases of traditional Chinese medicine and to uphold the development philosophy of equal emphasis on traditional Chinese medicine and western medicine，the China Association of Chinese Medicine has fully played a leading academic role by systematically organizing and conducting a series of academic youth salons on clinical dominant diseases of traditional Chinese medicine. On September 13，2024，the 36^th Youth Salon on Clinical Dominant Diseases was successfully held in Nanjing，focusing on the advantages of traditional Chinese medicine and the integrative traditional Chinese medicine and western medicine in the diagnosis and treatment of erectile dysfunction （ED）. The conference brought together leading experts from traditional Chinese medicine，western medicine，and interdisciplinary fields，facilitating in-depth multidisciplinary discussions that led to key consensus on optimizing traditional Chinese medicine treatment protocols for ED，researching and developing new drugs of traditional Chinese medicine，and advancing interdisciplinary development in traditional Chinese medicine. This salon systematically sorted out the clinical strengths and distinctive features of traditional Chinese medicine in the diagnosis and treatment of ED. Based on current research foundations and clinical needs，it identified key directions for future scientific layout and scientific research tackling： （1） Standardization of syndrome differentiation system of traditional Chinese medicine for ED. （2） Optimization and standardization of intervention methods of integrated traditional Chinese medicine and western medicine. （3） High-quality clinical research guided by evidence-based medicine. （4） In-depth analysis of the pharmacological mechanisms of traditional Chinese medicine in the treatment of ED. （5） Clinical translation and application promotion of new drugs of traditional Chinese medicine. （6） Interdisciplinary integration and innovation in traditional Chinese medicine. For each research direction，key focus areas，expected objectives，and clinical value were further refined，along with the establishment of a scientifically sound priority funding level evaluation system. Therefore，building on the series of salons on the ED-focused dominant diseases of traditional Chinese medicine，this paper provides standardized guidance for clinical practice of traditional Chinese medicine in ED management，effectively contributing to the high-quality development of traditional Chinese medicine. It serves as a valuable reference for national scientific and technological strategic layout， research and development decision-making in new drugs of traditional Chinese medicine，research topic planning，and clinical guideline formulation.

Polycystic ovary syndrome （PCOS） is a common endocrine and metabolic disorder among women of reproductive age. Hyperandrogenism （HA）， one of its core pathological features， is closely associated with the clinical manifestations and metabolic complications of the disease. Current western medical treatments for PCOS-HA mainly include anti-androgen therapy and ovulation induction， such as short-acting oral contraceptives like Diane-35 and Yasmin. However， long-term use of these medications may result in adverse reactions like increasing the risk of liver dysfunction and exacerbating lipid metabolism disorders， with unsatisfactory long-term efficacy when used alone. Traditional Chinese medicine offers unique advantages in the treatment of PCOS-HA due to its holistic approach and multi-target regulatory mechanisms. In the view of traditional Chinese medicine， PCOS-HA is classified under the categories such as "delayed menstruation"， "amenorrhea"， and "infertility"， with kidney deficiency as the root， as well as liver stagnation and spleen deficiency as the manifestations. Phlegm and blood stasis are considered to be intertwined throughout the disease course. Modern studies have shown that traditional Chinese medicine is significantly effective in improving the androgen levels， restoring ovulation， and improving insulin resistance in PCOS-HA patients. Representative prescriptions， such as Erxian Tang， Jiawei Xiaoyaosan， Guizhi Fulingwan， and Cangfu Daotantang， exert therapeutic effects through various mechanisms including regulation of the hypothalamic-pituitary-ovarian axis， reduction of ovarian androgen synthase activity， improvement of insulin signaling pathways， and inhibition of inflammation and oxidative stress， which demonstrates the characteristics of comprehensive treatment with traditional Chinese medicine. Based on the perspectives of etiology and pathogenesis of traditional Chinese medicine， modern medical cognition， typical prescriptions， and action mechanisms， this paper reviewed the research progress of traditional Chinese medicine in the treatment of PCOS-HA， aiming to provide a reference for in-depth research and clinical applications in this field.

Polycystic ovary syndrome （PCOS） is a common endocrine and metabolic disorder among women of reproductive age. Hyperandrogenism （HA）， one of its core pathological features， is closely associated with the clinical manifestations and metabolic complications of the disease. Current western medical treatments for PCOS-HA mainly include anti-androgen therapy and ovulation induction， such as short-acting oral contraceptives like Diane-35 and Yasmin. However， long-term use of these medications may result in adverse reactions like increasing the risk of liver dysfunction and exacerbating lipid metabolism disorders， with unsatisfactory long-term efficacy when used alone. Traditional Chinese medicine offers unique advantages in the treatment of PCOS-HA due to its holistic approach and multi-target regulatory mechanisms. In the view of traditional Chinese medicine， PCOS-HA is classified under the categories such as "delayed menstruation"， "amenorrhea"， and "infertility"， with kidney deficiency as the root， as well as liver stagnation and spleen deficiency as the manifestations. Phlegm and blood stasis are considered to be intertwined throughout the disease course. Modern studies have shown that traditional Chinese medicine is significantly effective in improving the androgen levels， restoring ovulation， and improving insulin resistance in PCOS-HA patients. Representative prescriptions， such as Erxian Tang， Jiawei Xiaoyaosan， Guizhi Fulingwan， and Cangfu Daotantang， exert therapeutic effects through various mechanisms including regulation of the hypothalamic-pituitary-ovarian axis， reduction of ovarian androgen synthase activity， improvement of insulin signaling pathways， and inhibition of inflammation and oxidative stress， which demonstrates the characteristics of comprehensive treatment with traditional Chinese medicine. Based on the perspectives of etiology and pathogenesis of traditional Chinese medicine， modern medical cognition， typical prescriptions， and action mechanisms， this paper reviewed the research progress of traditional Chinese medicine in the treatment of PCOS-HA， aiming to provide a reference for in-depth research and clinical applications in this field.

ObjectiveTo observe the effects of Yifei Tongluo prescription on the NOD-like receptor protein 3 （NLRP3）/Caspase-1/gasdermin D （GSDMD） pathway and epithelial-mesenchymal transition （EMT） in rats with pulmonary fibrosis. MethodsTracheal instillation of bleomycin was conducted to establish a rat model of pulmonary fibrosis. Thirty Sprague-Dawley （SD） rats were randomly divided into a blank group， a model group， a prednisone acetate group （1.17 mg·kg^-1）， and low- and high-dose Yifei Tongluo prescription groups （10.62 and 21.24 g·kg^-1， respectively）. Administration started on the 7th day after modeling， once a day for 28 consecutive days. The lung coefficient of each group was calculated. The pathological changes of lung tissues in each group were observed by hematoxylin-eosin （HE） staining and Masson staining. The expression of α-smooth muscle actin （α-SMA） and vimentin in rat lung tissues was detected by immunohistochemistry. The expression of NLRP3 inflammasome， E-cadherin （E-cad）， and typeⅠ collagen （ColⅠ） in lung tissues was detected by immunofluorescence. The content of hydroxyproline （HYP）， tumor necrosis factor （TNF）-α， interleukin （IL）-18， and IL-1β in rat serum was detected by enzyme-linked immunosorbent assay （ELISA）. The mRNA expression levels of NLRP3， apoptosis-associated speck-like protein containing a CARD （ASC）， IL-1β， and transforming growth factor （TGF）-β₁ in rat lung tissues were determined by real-time quantitative polymerase chain reaction （Real-time PCR）. The protein expression levels of NLRP3， GSDMD， ASC， and Caspase-1 in rat lung tissues were determined by Western blot. ResultsCompared with the blank group， the model group exhibited a significantly increased lung coefficient （P<0.01） and significantly increased range of pulmonary interstitial inflammation and collagen deposition. In addition， the levels of α-SMA， Vimentin， E-cad， and ColⅠ in lung tissues were significantly increased （P<0.01）. The levels of fibrosis- and inflammation-related factors HYP， TNF-α， IL-18， and IL-1β in serum were significantly upregulated （P<0.01）. The levels of factors related to the activation of NLRP3 inflammasome in lung tissues， including NLRP3， GSDMD， ASC， Caspase-1， IL-1β， and TGF-β₁， were significantly upregulated （P<0.01）. Compared with the model group， the Yifei Tongluo prescription groups showed improved lung coefficients. Additionally， the extent of lung inflammation and collagen deposition was significantly reduced. The expression of α-SMA， Vimentin， E-cad， and ColⅠ in lung tissue was significantly decreased （P<0.01）. The levels of HYP， TNF-α， IL-18， and IL-1β in serum were significantly reduced （P<0.01）. The expression levels of NLRP3， GSDMD， ASC， Caspase-1， IL-1β， and TGF-β₁ in lung tissue were also significantly decreased （P<0.01）. ConclusionYifei Tongluo prescription can regulate the NLRP3/Caspase-1/GSDMD pathway， down-regulate release of pro-inflammatory and pro-fibrotic cytokines， alleviate NLRP3 inflammasome-mediated pyroptosis and EMT， and thereby improve pulmonary fibrosis in rats.

Objective To investigate the distribution characteristics of pathogens causing infections within 90 days after liver transplantation and the influencing factors of infection. Methods Clinical data of 176 recipients who underwent liver transplantation at the Liver Transplant Center of Beijing Friendship Hospital Affiliated to Capital Medical University from September 2021 to August 2024 were retrospectively analyzed. Patients were divided into the infection group (n=124) and the non-infection group (n=52) based on whether they developed infection within 90 days after transplantation. The distribution characteristics of pathogens in infected patients were analyzed. Univariate and multivariate logistic regression analyses were used to explore the influencing factors of infection. Results Among the 176 liver transplant recipients, 124 cases developed 243 episodes of 518 bacterial, fungal, viral or mycoplasma infections within 90 days after transplantation, with an overall infection rate of 70.5% (124/176). The composition of pathogens was mainly Gram-negative bacteria (38.6%, 200/518), followed by Gram-positive bacteria (32.2%, 167/518) and viruses (15.4%, 80/518), and fungi accounted for 13.1% (68/518). Among Gram-negative bacteria, the main pathogen was Klebsiella pneumoniae (6.8%, 35/518), and among Gram-positive bacteria, the main pathogen was Enterococcus faecalis (8.5%, 44/518). Viruses included Epstein-Barr virus (3.7%, 19/518) and cytomegalovirus (3.7%, 19/518), and fungi were mainly Candida albicans (6.8%, 35/518). The most common infection site among the 243 episodes was pulmonary infection (42.0%, 102/243), followed by abdominal infection (22.6%, 55/243) and bloodstream infection (18.1%, 44/243). The infections mainly occurred within 2 weeks after transplantation (60.9%, 148/243). Multivariate logistic regression analysis indicated that preoperative infection within 2 weeks, a high preoperative model for end-stage liver disease (MELD) score, and preoperative sarcopenia were independent risk factors for infection within 90 days after liver transplantation (all odds ratio>1, P<0.05). After multivariate correction, the levels of CD4⁺T cells and CD8⁺T cells within 90 days after surgery were independently associated with the occurrence of infection. Low levels of CD4⁺T cells and CD8⁺T cells might be related to an increased risk of infection. Conclusions The infection rate after liver transplantation is high, and the pathogens are mainly Gram-negative bacteria. The lungs are the most common infection site. Preoperative MELD score, preoperative sarcopenia and preoperative infection within 2 weeks are independent risk factors for infection within 90 days after liver transplantation. Regular monitoring of immune indicators CD4⁺T cells and CD8⁺T cells levels after transplantation is helpful to reduce the occurrence of post-transplantation infection.

BACKGROUND:Age-related macular degeneration and deep vein thrombosis may share common pathophysiological mechanisms,but there is a lack of direct evidence regarding their relationship.Traditional studies are confounded by confounding factors and reverse causation.OBJECTIVE:To investigate the causal relationship between age-related macular degeneration and deep vein thrombosis based on Mendelian randomization design.METHODS:Through a two-way Mendelian randomization analysis,single nucleotide polymorphisms of exposure and outcomes were obtained from publicly available genome-wide association studies,with deep vein thrombosis data from the FinnGen database in a European population with a sample size of 363 612 and 1 048 575 single nucleotide polymorphisms.In addition,we obtained data on age-related macular degeneration from the IEUOpenGWAS project,also from a European population sample of 105 248 cases covering 11 304 110 single nucleotide polymorphisms.In R4.4.1,we used the TwoSampleMR package(version 0.6.8)to explore the causal effects of exposure factors on outcomes.At the same time,we also conducted a sensitivity analysis via MR-Egger regression,weighted median,weighted model and simple model methods to ensure that the assessment results were robust and reliable.In addition,we used the"heterogeneity"function to test for heterogeneity,and the"horizontal pleiotropy"function and the MR-PRESSO test to further assess horizontal pleotropy.The Cochran's Q test was used to determine whether there was statistical heterogeneity between single nucleotide polymorphisms,and the leave-one-out method was used to assess whether single nucleotide polymorphisms would significantly interfere with Mendelian randomization analysis.Funnel plots were drawn to assess the potential bias of single nucleotide polymorphisms.Forest plots were plotted to show the effect estimates of single nucleotide polymorphisms on exposure and outcomes,and their confidence intervals were plotted.Scatter plots were plotted to evaluate the relationship between the potency of single nucleotide polymorphisms and their causal effect size on outcome estimates.RESULTS AND CONCLUSION:Both forward and reverse studies showed that there was no causal association between age-related macular degeneration and the occurrence of deep vein thrombosis(P＞0.05).Sensitivity analysis showed that the main analysis results were reliable and robust,with no outliers,heterogeneity,and horizontal pleiotropy,and no single nucleotide polymorphism significantly affected the overall effect estimate.Although it is based on European population data,it has methodological reference value for Chinese biomedical research on complex disease associations.In this field,China can carry out multi-center large-sample studies,accurately analyze the internal links between Chinese population-related diseases,and provide a basis for prevention and treatment strategies and clinical practice.

Multidrug-resistant (MDR) bacterial infections have emerged as a serious challenge of global public health crisis. The overuse and misuse of conventional antibiotics have dramatically accelerated the emergence, evolution and worldwide spread of drug-resistant bacterial strains, necessitating urgent exploration of novel antibacterial strategies. Bacteriophages serve as natural bacterial predators offering distinct advantages including high host specificity, autonomous self-replication capabilities and cost-effective large-scale production. However, wild-type phages present significant clinical limitations due to their narrow host ranges, susceptibility to rapid immune clearance and poor penetration of bacterial biofilms, which severely restrict their therapeutic applications. The convergence of synthetic biology, nanotechnology and advanced gene editing technologies has accelerated the development of engineered bacteriophage platforms, providing programmable, scalable and clinically translatable pathways to overcome these inherent biological constraints. Here, we systematically delineate four fundamental strategies for engineered bacteriophage development. Chemical modification utilizes reactive functional groups such as amino, carboxyl and thiol moieties on capsid proteins through esterification, amidation or click chemistry reactions to achieve precise drug conjugation and surface functionalization. In vivo editing encompasses ultraviolet or chemical mutagenesis for random mutation induction, homologous recombination for targeted genetic alterations, recombineering methodologies including electroporation-mediated bacteriophage recombination engineering, and CRISPR-Cas systems for precise genome editing to enable exact genetic reconstruction and host range reprogramming. In vitro synthesis leverages genome engineering platforms where intact phage genomes are transferred into yeast or host bacteria to facilitate highly efficient homologous recombination, enabling large DNA fragment assembly and cross-gene host range expansion without bacterial toxicity constraints. Directed evolution combines artificial selection through mutation library screening with rational design approaches involving chimeric receptor binding protein construction or site-specific mutagenesis, effectively balancing the discovery of unknown adaptive pathways with targeted host specificity modification. Moreover, we comprehensively discuss therapeutic applications across diverse clinical scenarios. Engineered bacteriophage effectively disrupt bacterial biofilms through sophisticated functionalized delivery platforms including nanozyme-conjugated phages, phage-liposome nanoconjugates and bio-responsive hydrogels, demonstrating significantly enhanced bactericidal efficiency compared to unmodified free phages. These bioengineered vectors attenuate bacterial virulence and resensitize pathogens to antibiotics by delivering CRISPR-Cas systems or base editors to disrupt critical virulence factors such as pili, capsule synthesis machineries and quorum sensing systems, or by inactivating antibiotic resistance determinants including beta-lactamase genes. As an intelligent nanomedicine delivery platform, engineered bacteriophage enable precise pathogen elimination an through photocatalytic reactive oxygen species generation, immunomodulatory interventions, or controlled release of antibacterial drugs. Furthermore, oral administration of engineered bacteriophage facilitates microbiota modulation, which selectively eliminate intestinal pathogens while preserve beneficial commensal microbiota, thereby restoring microbial community balance and preventing complications associated with dysbiosis. Finally, we critically analyze persistent challenges including host strain matching complexity, evolution of bacterial resistance mechanisms, pharmacokinetic optimization requirements, optimal administration route selection, large-scale production quality control standards and clinical dosing determination protocols. Through multidisciplinary integration of synthetic biology, infectious disease medicine and immunology, future translational medicine studies of bacteriophage should establish comprehensive technical platforms encompassing rapid phage screening, intelligent rational design, rigorous in vivo evaluation and standardized clinical validation processes, ultimately advancing engineered bacteriophage from laboratory innovations to clinically approved therapeutics for effectively combating MDR bacterial infections.

Objective To explore the characteristics and correlation between perivascular spaces (PVS) and diffusion tensor image analysis along perivascular spaces (DTI-ALPS) index in patients with amnestic mild cognitive impairment (aMCI). Methods A retrospective study was conducted on a total of 118 participants, including cognitive normal (CN) healthy controls and aMCI patients, recruited from the Department of Neurology, Zhongshan Hospital, Fudan University from September 2020 to September 2022. All participants underwent structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). An automatic segmentation algorithm was used to quantify PVS metrics in the brain, and DTI-ALPS index was calculated based on DTI. Differences in DTI-ALPS index and PVS metrics between the CN and aMCI groups were compared. Multivariate logistic regression was used to identify independent factors influencing aMCI. Correlation analysis was performed to assess relationships among DTI-ALPS index, PVS metrics, and cognitive scores. Results A total of 80 CN healthy controls and 38 aMCI patients were included. The DTI-ALPS index was significantly lower in the aMCI group compared with the CN group (1.28±0.18 vs 1.37±0.21, P＝0.018), while differences in PVS metrics between groups were not statistically significant. Multivariate logistic regression analysis indicated that DTI-ALPS index was an independent factor affecting aMCI (OR＝0.097, 95%CI 0.011–0.833, P＝0.033). Correlation analysis revealed a positive relationship between DTI-ALPS index and MMSE score (r＝0.210, P＝0.023) as well as PVS length in the centrum semiovale (r＝0.216, P＝0.019). Conclusions The DTI-ALPS index may serve as an imaging biomarker for identifying early cognitive impairment, and patients with aMCI exhibit abnormal DTI-ALPS indices, suggesting that brain glymphatic system dysfunction may occur prior to morphological changes.

Objective To investigate the diagnosis and treatment of 2 cases with spontaneous renal vascular rupture, and discuss the possible causes and treatment methods of this disease. Methods The clinical data and treatment methods of the 2 patients with spontaneous renal vascular rupture treated with renal artery embolization in Universal Global Xi'an Beihuan Hospital were analyzed. Relevant literature was reviewed to summarize the possible causes of this condition. Results The patients had no obvious history of trauma and no obvious abnormal coagulation function, and sought treatment due to sudden lumbar and abdominal pain. Laboratory tests revealed significantly decreased hemoglobin level, and elevated blood glucose (27.8, 27.6mmol/L). Abdominal computed tomography (CT) indicated perirenal hematoma and active bleeding. The bleeding arteries were located at the terminal branches of the anterior renal artery. Precise embolization was performed using CT angiography and selective renal artery angiography plus embolization, achieving an immediate hemostasis success rate of 100%. Postoperative hemoglobin level stabilized, and follow-up CT scans showed significant absorption of the perirenal hematoma without significant deterioration of renal function. Based on literature review and case analysis, the possible cause of spontaneous renal vascular rupture in these two patients was renal vascular sclerosis due to long-term diabetes. Other common etiologies of this condition included renal tumor, vascular malformation, and hypertension. Conclusion Spontaneous renal vascular rupture is rare. Renal artery embolization, as aminimally invasive treatment, can effectively control bleeding and protect renal function. The specific pathogenesis of this condition still requires further investigation. Long-term diabetes mellitus with poor blood glucose control may be associated factors, but more evidence is needed.