GABAergic signaling between enteric neurons and intestinal smooth muscle promotes innate immunity and gut defense in Caenorhabditis elegans.

The nervous system is critical for intestinal homeostasis and function, but questions remain regarding its impact on gut immune defense. By screening the major neurotransmitters of C. elegans, we found that γ-aminobutyric acid (GABA) deficiency enhanced susceptibility to pathogenic Pseudomonas aeruginosa PA14 infection. GABAergic signaling between enteric neurons and intestinal smooth muscle promoted gut defense in a PMK-1/p38-dependent, but IIS/DAF-16- and DBL-1/TGF-ß-independent, pathway. Transcriptomic profiling revealed that the neuropeptide, FLP-6, acted downstream of enteric GABAergic signaling. Further data determined that FLP-6 was expressed and secreted by intestinal smooth muscle cells and functioned as a paracrine molecule on the intestinal epithelium. FLP-6 suppressed the transcription factors ZIP-10 and KLF-1 that worked in parallel and converged to the PMK-1/p38 pathway in the intestinal epithelia for innate immunity and gut defense. Collectively, these findings uncover an enteric neuron-muscle-epithelium axis that may be evolutionarily conserved in higher organisms.

Multi-Omics Profiling Identifies Microglial Annexin A2 as a Key Mediator of NF-κB Pro-inflammatory Signaling in Ischemic Reperfusion Injury.

Cerebral stroke is one of the leading causes of mortality and disability worldwide. Restoring the cerebral circulation following a period of occlusion and subsequent tissue oxygenation leads to reperfusion injury. Cerebral ischemic reperfusion (I/R) injury triggers immune and inflammatory responses, apoptosis, neuronal damage, and even death. However, the cellular function and molecular mechanisms underlying cerebral I/R-induced neuronal injury are incompletely understood. By integrating proteomic, phosphoproteomic, and transcriptomic profiling in mouse hippocampi after cerebral I/R, we revealed that the differentially expressed genes and proteins mainly fall into several immune inflammatory response-related pathways. We identified that Annexin 2 (Anxa2) was exclusively upregulated in microglial cells in response to cerebral I/R in vivo and oxygen-glucose deprivation and reoxygenation (OGD/R) in vitro. RNA-seq analysis revealed a critical role of Anxa2 in the expression of inflammation-related genes in microglia via the NF-κB signaling. Mechanistically, microglial Anxa2 is required for nuclear translocation of the p65 subunit of NF-κB and its transcriptional activity upon OGD/R in BV2 microglial cells. Anxa2 knockdown inhibited the OGD/R-induced microglia activation and markedly reduced the expression of pro-inflammatory factors, including TNF-α, IL-1ß, and IL-6. Interestingly, conditional medium derived from Anxa2-depleted BV2 cell cultures with OGD/R treatment alleviated neuronal death in vitro. Altogether, our findings revealed that microglia Anxa2 plays a critical role in I/R injury by regulating NF-κB inflammatory responses in a non-cell-autonomous manner, which might be a potential target for the neuroprotection against cerebral I/R injury.

The bZIP transcription factor BATF3/ZIP-10 suppresses innate immunity by attenuating PMK-1/p38 signaling.

Innate immunity is the first line of host defense against pathogenic invasion in metazoans. The transcription factor basic leucine zipper transcriptional factor ATF-like 3 (BATF3) plays a crucial role in the development of conventional dendritic cells and the program of CD8 + T cell survival and memory, but the role of BATF3 in innate immune responses remains unclear. Here, we show an evolutionarily conserved basic-region leucine zipper (bZIP) transcription factor BATF3/ZIP-10 suppresses innate immune response through repressing the p38/PMK-1 mitogen-activated protein kinase (MAPK) pathway in vitro and in vivo. The worm mutant lacking the Caenorhabditis elegans homolog BATF3, ZIP-10, exhibited enhanced resistance to PA14 infection, which was completely rescued by transgenic expression of either endogenous zip-10 or mouse or human Batf3 cDNA driven by the worm zip-10 promoter. ZIP-10 expression was inhibited by a microRNA miR-60 that was downregulated upon PA14 infection. Moreover, the level of phosphorylated but not total PMK-1/p38 was attenuated by ZIP-10 and stimulated by miR-60. The human HEK293 cells with Batf3 overexpression or RNA-interference knockdown exhibited a reduction or increase of the cell viability upon Pseudomonas aeruginosa PA14 infection, respectively. The overexpression of either worm ZIP-10 or human BATF3 abolished the activation of p38 and inhibited the expression of antimicrobial peptides and cytokine genes in HEK293 cells. Our findings indicate that the genetic transcriptional program of the evolutionally conserved bZIP transcription factor BATF3/ZIP-10 suppresses innate immunity by attenuating the p38 MAPK signaling activity, which expands our understanding of the pathological mechanisms underlying relevant infectious diseases.

Phosphoproteome Analysis Identifies a Synaptotagmin-1-Associated Complex Involved in Ischemic Neuron Injury.

Cerebral stroke is one of the leading causes of death in adults worldwide. However, the molecular mechanisms of stroke-induced neuron injury are not fully understood. Here, we obtained phosphoproteomic and proteomic profiles of the acute ischemic hippocampus by LC-MS/MS analysis. Quantitative phosphoproteomic analyses revealed that the dysregulated phosphoproteins were involved in synaptic components and neurotransmission. We further demonstrated that phosphorylation of Synaptotagmin-1 (Syt1) at the Thr112 site in cultured hippocampal neurons aggravated oxygen-glucose deprivation-induced neuronal injury. Immature neurons with low expression of Syt1 exhibit slight neuronal injury in a cerebral ischemia model. Administration of the Tat-Syt1T112A peptide protects neurons against cerebral ischemia-induced injury in vitro and in vivo. Surprisingly, potassium voltage-gated channel subfamily KQT member 2 (Kcnq2) interacted with Syt1 and Annexin A6 (Anxa6) and alleviated Syt1-mediated neuronal injury upon oxygen-glucose deprivation treatment. These results reveal a mechanism underlying neuronal injury and may provide new targets for neuroprotection after acute cerebral ischemia onset.

Membranes for olefin-paraffin separation: An industrial perspective.

In the next decade, separation science will be an important research topic in addressing complex challenges like reducing carbon footprint, lowering energy cost, and making industrial processes simpler. In industrial chemical processes, particularly in petrochemical operations, separation and product refining steps are responsible for up to 30% of energy use and 30% of the capital cost. Membranes and adsorption technologies are being actively studied as alternative and partial replacement opportunities for the state-of-the-art cryogenic distillation systems. This paper provides an industrial perspective on the application of membranes in industrial petrochemical cracker operations. A gas separation performance figure of merit for propylene/propane separation for different classes of materials ranging from inorganic, carbon, polymeric, and facilitated transport membranes is also reported. An in-house-developed model provided insights into the importance of operational parameters on the overall membrane design.

GABAergic synapses suppress intestinal innate immunity via insulin signaling in Caenorhabditis elegans.

GABAergic neurotransmission constitutes a major inhibitory signaling mechanism that plays crucial roles in central nervous system physiology and immune cell immunomodulation. However, its roles in innate immunity remain unclear. Here, we report that deficiency in the GABAergic neuromuscular junctions (NMJs) of Caenorhabditis elegans results in enhanced resistance to pathogens, whereas pathogen infection enhances the strength of GABAergic transmission. GABAergic synapses control innate immunity in a manner dependent on the FOXO/DAF-16 but not the p38/PMK-1 pathway. Our data reveal that the insulin-like peptide INS-31 level was dramatically decreased in the GABAergic NMJ GABAAR-deficient unc-49 mutant compared with wild-type animals. C. elegans with ins-31 knockdown or loss of function exhibited enhanced resistance to Pseudomonas aeruginosa PA14 exposure. INS-31 may act downstream of GABAergic NMJs and in body wall muscle to control intestinal innate immunity in a cell-nonautonomous manner. Our results reveal a signaling axis of synapse-muscular insulin-intestinal innate immunity in vivo.

Three-Field Versus Two-Field Lymphadenectomy in Minimally Invasive Esophagectomy: 3-Year Survival Outcomes of a Randomized Trial.

BACKGROUND: Minimally invasive esophagectomy (MIE) has been used widely for the treatment of esophageal cancer. However, the optimal extent of lymphadenectomy for esophagectomy in MIE remains unclear. This trial aimed to investigate the 3-year survival and recurrence outcomes in a randomized controlled trial comparing MIE with either three-field lymphadenectomy (3-FL) or two-field lymphadenectomy (2-FL). METHODS: Between June 2016 and May 2019, 76 patients with resectable thoracic esophageal cancer were enrolled in a single-center randomized controlled trial and randomly assigned to MIE that included either 3-FL or 2-FL at a 1:1 ratio (n = 38 patients each). The survival outcomes and recurrence patterns were compared between the two groups. RESULTS: The 3-year cumulative overall survival (OS) probability was 68.2 % (95 % confidence interval [CI], 52.72-83.68 %) for the 3-FL group and 68.6 % (95 % CI, 53.12-84.08 %) for the 2-FL group. The 3-year cumulative probability of disease-free survival (DFS) was 66.3 % (95 % CI, 50.03-82.57 %) for the 3-FL group and 67.1 % (95 % CI, 51.03-83.17 %) for the 2-FL group.. The OS and DFS differences in the two groups were comparable. The overall recurrence rate did not differ significantly between the two groups (P = 0.737). The incidence of cervical lymphatic recurrence in the 2-FL group was higher than in the 3-FL group (P = 0.051). CONCLUSIONS: Compared with 2-FL in MIE, 3-FL tended to prevent cervical lymphatic recurrence. However, it was not found to add survival benefit for the patients with thoracic esophageal cancer.

ZBTB7A, a miR-144-3p targeted gene, accelerates bladder cancer progression via downregulating HIC1 expression.

BACKGROUND: Zinc finger and BTB domain-containing 7A (ZBTB7A) is a member of the POK family of transcription factors that plays an oncogenic or tumor-suppressive role in different cancers depending on the type and genetic context of cancer. However, the function and molecular mechanism of ZBTB7A in bladder cancer (BC) remain elusive. METHODS: The role of ZBTB7A in bladder cancer was detected by colony formation, transwell, and tumor formation assays. The expression levels of ZBTB7A, HIC1, and miR-144-3p were analyzed by qRT-PCR and Western blot. Bioinformatics analysis and a dual-luciferase reporter assay were used to assess the effect of ZBTB7A on the promoter activity of HIC1. RESULTS: The present study revealed that knockdown of ZBTB7A suppressed BC cell growth and migration, as indicated by an approximately 50% reduction in the number of colonies and an approximately 70% reduction in the number of migrated cells. Loss of ZBTB7A inhibited tumor growth in vivo, resulting in a 75% decrease in tumor volume and an 80% decrease in tumor weight. Further mechanistic studies revealed that ZBTB7A bound to the hypermethylated in cancer 1 (HIC1) promoter and downregulated HIC1 expression, accelerating the malignant behavior of BC. Increased expression of ZBTB7A in BC tissues was negatively corrected with the expression of HIC1. Moreover, ZBTB7A was a target of miR-144-3p, which decreased ZBTB7A expression in BC. CONCLUSION: Our data demonstrate that ZBTB7A, a targeted gene of miR-144-3p, promoted tumorigenesis of BC through downregulating HIC1 expression.

Inequality in the last resort: how medical appraisal affects malpractice litigations in China.

BACKGROUND: Medical malpractice litigations affect the practices of patient safety. However, medical malpractice litigations involve highly specialized knowledge. Thus, medical appraisal is usually essential in the ascertainment of responsibility and judicial decision-making. China's judicial system is characterized by a dual-mode of medical appraisal resulting from two parallel appraisal agencies: judicial appraisal institutions and medical associations. This paper examines whether or not and how choices of different medical appraisal agencies affect malpractice lawsuit results in China. METHODS: We collected and sampled a total of 2557 verdicts pertaining to medical disputes from "China Judgements Online" in 2014. We used an ordinary least square regression model and a mediating effect regression model to analyze to what extent and how different choices between two medical appraisal agencies affect malpractice litigations. RESULTS: (1) Almost 81.55% (2082) of litigants resorted to medical malpractice appraisals in China in 2014. Among 2070 cases with appraisal results accepted by the court, 60.10% of the litigants chose judicial appraisal institutions (1244), as opposed to medical associations (826). (2) Among 2557 cases, 2306 (90.18%) claimed compensation and 1919 (83.22%) were awarded compensation by the courts. The proportion of compensation paid in a case is 48% on average. (3) Appraisal agencies matter in the investigation of medical errors, which in turn affects the proportion of compensation paid in a case. (4) Choosing judicial appraisal institutions will raise the proportion of compensation paid by about 10% on average. CONCLUSIONS: Different choices between appraisal institutions affect malpractice litigations in China. As the last resort for remedying medical malpractice, medical appraisals in the judicial system could be a source of inequality in China's medical litigation outcomes.

Linc-RoR promotes proliferation, migration, and invasion via the Hippo/YAP pathway in pancreatic cancer cells.

Large intergenic noncoding RNA regulator of reprogramming (Linc-RoR) was first identified as a regulator to increase the emergence of induced pluripotent stem cells through reprogramming differentiated cells and is abnormal expression in a variety of malignant tumors. However, the function of Linc-RoR in pancreatic cancer progression needs further clarification. The data from this study demonstrated that Linc-RoR knockdown suppressed cell proliferative capacity and colony formation, while Linc-RoR overexpression promoted these behaviors. In particular, Linc-RoR overexpression promoted the level of mesenchymal markers, inhibited the expression of epithelial markers, as well as enhanced pancreatic cancer cells migration and invasion, whereas Linc-RoR knockdown inhibited the expression of mesenchymal markers, promoted the expression of epithelial markers, as well as weakened pancreatic cancer cells migration and invasion. Further study revealed that Linc-RoR knockdown brought about a significant fall in YAP phosphorylation and a rise in total YAP, while Linc-RoR overexpression produced the opposite results. Specifically, Linc-RoR promoted YAP in the cytoplasm into the nucleus. Taken together, we conjectured that Linc-RoR promoted proliferation, migration, and invasion of pancreatic cancer cells by activating the Hippo/YAP pathway. YAP might be an underlying target of Linc-RoR and mediate epithelial-mesenchymal transition (EMT) in pancreatic cancer (PC); thus, Linc-RoR might be a very meaningful biomarker for PC.

The unsynchronized changes of CT image and nucleic acid detection in COVID-19: reports the two cases from Gansu, China.

The novel coronavirus disease (COVID-19) outbreak started in December 2019 in Wuhan, China, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The CT image is used to assess the disease progress, whereas the continued two times of negative results from SARS-CoV-2 nucleic acid detection had been considered as a criterion for ending antiviral treatment. We compared the two COVID-19 cases with similar backgrounds and CT image repeated intervals under treatment. Our report highlighted the unsynchronized expression in the changes of CT image and nucleic acid detection in COVID-19, and lasting positive nucleic acid test result in patients recovered from pneumonia. It may be contributed to recognize the disease and improve prevention.

Downregulation of IQGAP1 inhibits epithelial-mesenchymal transition via the HIF1α/VEGF-A signaling pathway in gastric cancer.

As an oncogene, IQ-domain GTPase-activating protein 1 (IQGAP1) regulates the epithelial-mesenchymal transition (EMT) of several cancers, such as breast cancer, thyroid cancer, and esophageal squamous cell carcinoma. However, the role of the scaffold protein IQGAP1 on EMT in gastric cancer remains unclear. Therefore, the present work was performed to address the question. Our results showed that IQGAP1 expression is upregulated in human gastric cancer specimens and cell lines. Furthermore, IQGAP1 knockdown inhibited the migratory ability of gastric cancer cells and reduced the expression of mesenchymal phenotype markers, including Slug, ß-catenin, Snail, Vimentin, and N-cadherin, as well as vascular endothelial growth factor-A (VEGF-A) secretion in gastric cancer cells. Conversely, IQGAP1 downregulation increased the epithelial phenotype marker E-cadherin. Furthermore, IQGAP1 silencing not only downregulated hypoxia-inducible transcription factor 1α (HIF1α) but also limited its translocation from the cytosol to the nucleus. Collectively, our results indicated that EMT was regulated by IQGAP1, which was associated with VEGF-A, since other data demonstrated that HIF1α was involved in VEGF-A expression. Therefore, we speculated that IQGAP1 regulated EMT of gastric cancer partially via the HIF1α/VEGF-A signaling pathway. IQGAP1 may serve as an effective therapeutic biomarker for gastric cancer.

The safety and efficiency of retroperitoneal laparoscopic adrenalectomy via extra and intra perinephric fat approaches: a retrospective clinical study.

BACKGROUND: This retrospective clinical study is to evaluate the safety and efficiency of two different approaches in retroperitoneal laparoscopic adrenalectomy and provide experience and basis for the treatment of adrenal tumors through retroperitoneal approach. METHODS: From July 2015 to February 2018, 112 patients with adrenal lesions underwent retroperitoneal laparoscopic adrenalectomy (RLA) using a 3-port method. Among them, 56 patients underwent RLA via the extra perinephric fat approach (EPFA), 56 patients underwent RLA via the intra perinephric fat approach (IPFA). Clinical data, including preoperative, operative and postoperative management were recorded. RESULTS: All surgeries were successfully completed, and there was no single patient who died during these surgeries. There was no statistically significant difference between the two groups in blood loss, postoperative complications, vena cava injury, renal cortex injury, peripheral organ injury, and post operation hospital stay. Peritoneum injury occurred more frequently in the EPFA group when compared with the IPEA group (p = 0.042). The average surgery time of the IPEA group is significantly shorter when compared with that of the EPEA group (p < 0.001). Due to serious saponification of the perinephric fat and heavy adhesion to renal fascia, three cases in IPFA group were converted to the EPFA surgery. CONCLUSION: RLA is a safe and effective procedure both via extra perinephric fat and intra perinephric fat approaches. IPEA is superior to EPEA in terms of peritoneal injury and duration. The choice may mainly depend on the experience of the surgeon, the characteristics of the adrenal tumor and the nature of the perinephric fat.

KLF4, a miR-32-5p targeted gene, promotes cisplatin-induced apoptosis by upregulating BIK expression in prostate cancer.

BACKGROUND: Chemotherapeutic insensitivity remains a big challenge in prostate cancer treatment. Recently, increasing evidence has indicated that KLF4 plays a key role in prostate cancer. However, the potential biological role of KLF4 in Chemotherapeutic insensitivity of prostate cancer is still unknown. METHODS: The role of KLF4 in cisplatin-induced apoptosis was detected by western blotting and a cell counting kit (CCK8). The potential molecular mechanism of KLF4 in regulating prostate cancer chemosensitivity was investigated by RNA sequencing analysis, q-RT-PCR, western blotting and chromatin immunoprecipitation (ChIP). The expression level of KLF4 mediated by miR-32-5p was confirmed by bioinformatic analysis and luciferase assays. RESULTS: Here, we found that KLF4 was induced by cisplatin in prostate cancer cells and that the increase in KLF4 promoted cell apoptosis. Further mechanistic studies revealed that KLF4 directly bound to the promoter of BIK, facilitating its transcription. Additionally, we also found that the gene encoding KLF4 was a direct target of miR-32-5p. The downregulation of miR-32-5p in response to cisplatin treatment promoted KLF4 expression, which resulted in a increase in the chemosensitivity of prostate cancer. CONCLUSION: Thus, our data revealed that KLF4 is an essential regulator in cisplatin-induced apoptosis, and the miR-32-5p-KLF4-BIK signalling axis plays an important role in prostate cancer chemosensitivity.

Amino acids regulate mTOR pathway and milk protein synthesis in a mouse mammary epithelial cell line is partly mediated by T1R1/T1R3.

PURPOSE: The mechanism of dietary amino acids in regulating milk protein synthesis at the translational level is not well understood. Numerous studies have shown that the amino acid signal is transferred through the mammalian target of rapamycin (mTOR) pathway; however, the extracellular amino acid-sensing mechanism that activates mTOR complex 1 is unknown. We tested the hypotheses that the T1R1/T1R3 heterodimer functions as a direct sensor of the fed state and amino acid availability preceding the mTOR pathway and affects milk protein synthesis in mammary epithelial cells. METHODS: The expression of T1R1 was repressed by T1R1 siRNA in mouse mammary epithelial cells model (HC11). Western blot was used to analyze activity of the mTOR pathway and ß-casein expression, and quantitative real-time RT-PCR was used to analyze the change in mRNA abundance of amino acid transporters. RESULTS: The transcripts and proteins of T1R1 and T1R3 were detected in HC11 cells and mouse mammary gland tissue. siRNA silencing of T1R1 repressed ß-casein synthesis in HC11 cells both with and without essential amino acids present in the culture medium. The phosphorylation of mTOR, S6K, and 4EBP1 in T1R1 knockdown HC11 cells declined to 25, 50, and 30 %, indicating T1R1 knockdown repressed the activity of the mTOR pathway. T1R1 knockdown increased the mRNAs coding three important amino acid transporters (SLC1A5 and SLC3A2/SLC7A5). Activation of the mTOR pathway was partially repressed by T1R1 siRNA or SLC7A5/SLC3A2 inhibitor (BCH, 10 mM), and the combination of these two treatments further repressed the activity of this pathway. CONCLUSION: T1R1/T1R3 serves as sensor of extracellular amino acids in mouse mammary epithelial cells and involved in milk protein synthesis regulation.

Circular RNA of cattle casein genes are highly expressed in bovine mammary gland.

Recent studies have revealed that, in addition to hormones and other protein factors, noncoding RNA molecules play an important regulatory role in milk protein synthesis. Circular RNAs (circRNAs) are universally expressed noncoding RNA species that have been proposed recently to regulate the expression of their parental genes. In the present study, the deep RNA-sequencing technique known as RNA-seq was used to compare expression profiles of circRNAs from 2 pooled RNA samples from cow mammary gland on d 90 and 250 postpartum and to identify the key circRNAs involved in lactation. A total of 4,804 and 4,048 circRNAs were identified in the cow mammary gland on d 90 and 250 postpartum, respectively, of which only 2,231 circRNAs were co-expressed at both lactation stages, suggesting high stage specificity in the circRNAs. The enrichment of some Gene Ontology terms for the circRNA parental genes differed between lactation stages. Among the top 10 enriched Gene Ontology terms, vesicle, endoplasmic reticulum, and mitochondrial lumen were more common on lactation d 90. All 4 casein-coding genes (CSN1S1, CSN1S2, CSN2, and CSN3) produced circRNAs in the cattle mammary gland. In total, 80 circRNAs were identified from these 4 genes; circRNAs from CSN1S1 had very high abundance, and 3 of them accounted for 36% of all the circRNAs expressed in the mammary gland on lactation d 90. Three circRNAs from CSN1S1, 1 circRNA from CSN1S2, and 1 circRNA from CSN2 were all more highly expressed on lactation d 90 than on lactation d 250, as confirmed by quantitative PCR. These circRNAs had several target sites for the microRNA miR-2284 family and were predicted to target CSN1S1 and CSN2 mRNA, suggesting their potential involvement in regulating expression of the casein genes.

Improvement of a Privacy Authentication Scheme Based on Cloud for Medical Environment.

Medical systems allow patients to receive care at different hospitals. However, this entails considerable inconvenience through the need to transport patients and their medical records between hospitals. The development of Telecare Medicine Information Systems (TMIS) makes it easier for patients to seek medical treatment and to store and access medical records. However, medical data stored in TMIS is not encrypted, leaving patients' private data vulnerable to external leaks. In 2014, scholars proposed a new cloud-based medical information model and authentication scheme which would not only allow patients to remotely access medical services but also protects patient privacy. However, this scheme still fails to provide patient anonymity and message authentication. Furthermore, this scheme only stores patient medical data, without allowing patients to directly access medical advice. Therefore, we propose a new authentication scheme, which provides anonymity, unlinkability, and message authentication, and allows patients to directly and remotely consult with doctors. In addition, our proposed scheme is more efficient in terms of computation cost. The proposed system was implemented in Android system to demonstrate its workability.

Protocol for survival assay of Caenorhabditis elegans to Pseudomonas aeruginosa PA14 infection.

The nematode Caenorhabditis elegans is a powerful model organism for studying the molecular and cellular mechanisms of innate immunity governed by the intestine. Here, we present a protocol to perform C. elegans survival assays to infection by the bacterial pathogen Pseudomonas aeruginosa PA14. Specifically, we describe steps for preparing C. elegans strains and PA14 bacteria for survival assays. This protocol will assist researchers to study genes involved in intestinal innate immunity and gut defense against pathogen infection. For complete details on the use and execution of this protocol, please refer to Liu et al.1 and Zheng et al.2.

Influence of different position modal parameters on milling chatter stability of orthopedic surgery robots.

This research is dedicated to exploring the dynamics of milling chatter stability in orthopedic surgery robots, focusing on the impact of position modal parameters on chatter stability. Initially, we develop a dynamic milling force model for the robotic milling process that integrates both modal coupling and regenerative effects. We then employ the zero-order frequency domain method to derive a chatter stability domain model, visually represented through stability lobe diagrams (SLDs). Through conducting hammer test experiments, we ascertain the robot's modal parameters at varying positions, enabling the precise generation of SLDs. This study also includes experimental validation of the chatter SLD analysis method, laying the groundwork for further examination of chatter stability across different positional modal parameters. Finally, our analysis of the variations in modal parameters on the stability of robot milling chatter yields a theoretical framework for optimizing cutting parameters and developing control strategies within the context of orthopedic surgery robots.