Structure of a key intermediate of the SMN complex reveals Gemin2's crucial function in snRNP assembly.

The SMN complex mediates the assembly of heptameric Sm protein rings on small nuclear RNAs (snRNAs), which are essential for snRNP function. Specific Sm core assembly depends on Sm proteins and snRNA recognition by SMN/Gemin2- and Gemin5-containing subunits, respectively. The mechanism by which the Sm proteins are gathered while preventing illicit Sm assembly on non-snRNAs is unknown. Here, we describe the 2.5 Å crystal structure of Gemin2 bound to SmD1/D2/F/E/G pentamer and SMN's Gemin2-binding domain, a key assembly intermediate. Remarkably, through its extended conformation, Gemin2 wraps around the crescent-shaped pentamer, interacting with all five Sm proteins, and gripping its bottom and top sides and outer perimeter. Gemin2 reaches into the RNA-binding pocket, preventing RNA binding. Interestingly, SMN-Gemin2 interaction is abrogated by a spinal muscular atrophy (SMA)-causing mutation in an SMN helix that mediates Gemin2 binding. These findings provide insight into SMN complex assembly and specificity, linking snRNP biogenesis and SMA pathogenesis.

Crystal structure and function analysis of 6-phosphogluconate dehydrogenase in Mycobacterium tuberculosis.

6-phosphogluconate dehydrogenase (6PGDH) is an essential enzyme in energy metabolism and redox reactions, and represents a potential drug target for the development of therapies targeting trypanosomes, plasmodium, or other pathogens. Tuberculosis, caused by Mycobacterium tuberculosis, is a contagious disease that severely affects human health, with approximately one-third of the world's population infected. However, the protein structure, exact oligomeric state, and catalytic mechanism of 6PGDH in Mycobacterium tuberculosis (Mt6PGDH) have remained largely unknown. In this study, we successfully purified and determined the structure of Mt6PGDH, revealing its function as a tetramer in both solution and crystal states. Through structural comparisons, we clarified the tetramer formation mechanism and the oligomeric organization of short-chain 6PGDHs. Additionally, we identified key residues for coenzyme recognition and catalytic activity. This work not only deepens our understanding of the enzymatic function of Mt6PGDH but also lays a foundation for the development of drugs targeting this enzyme.

Transformation to small cell lung cancer is irrespective of EGFR and accelerated by SMAD4-mediated ASCL1 transcription independently of RB1 in non-small cell lung cancer.

OBJECTIVES: Histological transformation to small cell lung cancer (SCLC) has been identified as a mechanism of TKIs resistance in EGFR-mutant non-small cell lung cancer (NSCLC). We aim to explore the prevalence of transformation in EGFR-wildtype NSCLC and the mechanism of SCLC transformation, which are rarely understood. METHODS: We reviewed 1474 NSCLC patients to investigate the NSCLC-to-SCLC transformed cases and the basic clinical characteristics, driver gene status and disease course of them. To explore the potential functional genes in SCLC transformation, we obtained pre- and post-transformation specimens and subjected them to a multigene NGS panel involving 416 cancer-related genes. To validate the putative gene function, we established knocked-out models by CRISPR-Cas 9 in HCC827 and A549-TP53-/- cells and investigated the effects on tumor growth, drug sensitivity and neuroendocrine phenotype in vitro and in vivo. We also detected the expression level of protein and mRNA to explore the molecular mechanism involved. RESULTS: We firstly reported an incidence rate of 9.73% (11/113) of SCLC transformation in EGFR-wildtype NSCLC and demonstrated that SCLC transformation is irrespective of EGFR mutation status (P = 0.16). We sequenced 8 paired tumors and identified a series of mutant genes specially in transformed SCLC such as SMAD4, RICTOR and RET. We firstly demonstrated that SMAD4 deficiency can accelerate SCLC transition by inducing neuroendocrine phenotype regardless of RB1 status in TP53-deficient NSCLC cells. Further mechanical experiments identified the SMAD4 can regulate ASCL1 transcription competitively with Myc in NSCLC cells and Myc inhibitor acts as a potential subsequent treatment agent. CONCLUSIONS: Transformation to SCLC is irrespective of EFGR status and can be accelerated by SMAD4 in non-small cell lung cancer. Myc inhibitor acts as a potential therapeutic drug for SMAD4-mediated resistant lung cancer. Video Abstract.

Significance of Ultra-Radical Surgery in Extensive Metastatic Ovarian Growing Teratoma Syndrome.

INTRODUCTION: The aim of the study was to evaluate the perioperative risks and outcomes of ultra-radical surgery in patients with extensive metastatic ovarian growing teratoma syndrome (GTS). METHODS: We conducted a retrospective study of patients with extensive metastatic ovarian GTS treated in our hospital between 2000 and 2022. Patients' clinical characteristics, surgical treatment, and outcomes were evaluated. RESULTS: Overall, 13 patients were identified, and the median age at diagnosis of ovarian immature teratoma (IT) was 24 years (range: 5-37). The median interval between IT diagnosis and presenting GTS was 8 months (range: 2-60), with a median surgery delay of 5 months (range: 3-300). Peritoneum and liver were the most commonly affected sites (100%), followed by bowel (12 patients, 92.3%), diaphragm (12 patients, 92.3%), adnexa (9 patients, 69.2%), omentum (8 patients, 61.5%), uterus (7 patients, 53.8%), in the descending order. The mean operation time was 316 min (range: 180-625), and the mean blood loss volume was 992 mL (range: 200-5,000). Peritoneal metastasectomy (13 patients, 100%), diaphragmatic metastasectomy (12 patients, 92.3%), metastasis removal from the bowel (8 patients, 61.5%), partial hepatectomy (4 patients, 30.8%), bowel excision and anastomosis (1 patient, 7.7%) were also applied to achieve optimal debulking. R0 was achieved in 9 (69.2%) patients. A high rate of intraoperative blood transfusion (8 patients, 61.5%) and admission to the intensive care unit (9 patients, 69.2%) were observed, and the median postoperative hospitalization time was 8 days (range: 4-22). After a median follow-up of 3.3 years, 9 patients were free of disease, and 4 were alive with stable residual diseases. CONCLUSION: The survival outcomes in extensive metastatic ovarian GTS were satisfactory after ultra-radical surgery, while a proper therapeutic plan should be established due to the high perioperative risks.

Survival outcomes and establishment of a novel risk stratification system in patients with ovarian yolk sac tumors.

OBJECTIVE: To evaluate the survival outcomes and establish a risk stratification system in patients with ovarian yolk sac tumors (OYST). METHODS: The recurrence-free survival (RFS), disease-specific survival (DSS), and prognostic factors were retrospectively evaluated in 151 OYST patients treated in our hospital between 2006 and 2022. A risk stratification system based on the identified prognostic factors was established. RESULTS: The median follow-up time was 5.1 years, with a 5-year RFS and DSS rate of 75.5% and 91.2%, respectively. FIGO stage III-IV and the interval between treatment and normalization of AFP were two prognostic predictors. Significant differences in RFS and DSS (both P < 0.001) were identified between patients who had normalized AFP ≤ 3 and ≥ 4 cycles of chemotherapy, or among patients who had normalized AFP after ≤2, 3-4, and ≥ 5 cycles of chemotherapy. FIGO stage I - II and stage III-IV were scored as 0 and 2, respectively. AFP normalization ≤2, 3, 4, and ≥ 5 cycles of chemotherapy were scored as 0, 1, 2, and 4, respectively. A total score of 0-1, 2-3, and ≥ 4 were stratified patients into low-risk (96 patients), intermediate-risk (35 patients), and high-risk groups (20 patients), respectively. Patients in three risk stratifications manifested significant differences in both RFS and DSS (P < 0.0001). CONCLUSION: This risk stratification system based on tumor stage and the interval between treatment and normalization of AFP may help to guide clinical management by dividing OYST patients into three risk groups.

Current Research of Botulinum Toxin Type A in Prevention and Treatment on Pathological Scars.

BACKGROUND: Dermatologists have been looking for ways to improve wound healing and postoperative scar appearance. The safety and efficacy of botulinum toxin type A (BTXA) in the prevention and treatment on pathological scars have become the current research hotspot since it was approved by the US FDA in medical cosmetology in 2002. PURPOSE: This article aims to provide an overview of the clinical research, limitations, and application prospects of BTXA in the prevention and treatment of traumatic or postoperative pathological scars, which can provide a reference and better understanding of relevant studies. METHODS: The current research progress was summarized and discussed, with new problems and research ideas being proposed ranging from the molecular mechanism of BTXA in preventing and treating pathological scars to its clinical application via investigation and reference research. RESULTS: BTXA is effective in relieving itching and pain associated with pathological scars, limiting scar hyperplasia along with preventing scar contracture, but the specific mechanism is still not clear. CONCLUSION: Most of the clinicians have confirmed the clinical effectiveness of BTXA in the prevention and treatment of pathological scars, yet its mode of action and combination therapy need more research.

A Method for Detecting LDoS Attacks in SDWSN Based on Compressed Hilbert-Huang Transform and Convolutional Neural Networks.

Currently, Low-Rate Denial of Service (LDoS) attacks are one of the main threats faced by Software-Defined Wireless Sensor Networks (SDWSNs). This type of attack uses a lot of low-rate requests to occupy network resources and hard to detect. An efficient detection method has been proposed for LDoS attacks with the features of small signals. The non-smooth small signals generated by LDoS attacks are analyzed employing the time-frequency analysis method based on Hilbert-Huang Transform (HHT). In this paper, redundant and similar Intrinsic Mode Functions (IMFs) are removed from standard HHT to save computational resources and to eliminate modal mixing. The compressed HHT transformed one-dimensional dataflow features into two-dimensional temporal-spectral features, which are further input into a Convolutional Neural Network (CNN) to detect LDoS attacks. To evaluate the detection performance of the method, various LDoS attacks are simulated in the Network Simulator-3 (NS-3) experimental environment. The experimental results show that the method has 99.8% detection accuracy for complex and diverse LDoS attacks.

Negative cooperativity between Gemin2 and RNA provides insights into RNA selection and the SMN complex's release in snRNP assembly.

The assembly of snRNP cores, in which seven Sm proteins, D1/D2/F/E/G/D3/B, form a ring around the nonameric Sm site of snRNAs, is the early step of spliceosome formation and essential to eukaryotes. It is mediated by the PMRT5 and SMN complexes sequentially in vivo. SMN deficiency causes neurodegenerative disease spinal muscular atrophy (SMA). How the SMN complex assembles snRNP cores is largely unknown, especially how the SMN complex achieves high RNA assembly specificity and how it is released. Here we show, using crystallographic and biochemical approaches, that Gemin2 of the SMN complex enhances RNA specificity of SmD1/D2/F/E/G via a negative cooperativity between Gemin2 and RNA in binding SmD1/D2/F/E/G. Gemin2, independent of its N-tail, constrains the horseshoe-shaped SmD1/D2/F/E/G from outside in a physiologically relevant, narrow state, enabling high RNA specificity. Moreover, the assembly of RNAs inside widens SmD1/D2/F/E/G, causes the release of Gemin2/SMN allosterically and allows SmD3/B to join. The assembly of SmD3/B further facilitates the release of Gemin2/SMN. This is the first to show negative cooperativity in snRNP assembly, which provides insights into RNA selection and the SMN complex's release. These findings reveal a basic mechanism of snRNP core assembly and facilitate pathogenesis studies of SMA.

The Cupin Protein Pac13 is Suggested by the Data to Be a Homodimer.

Cupin proteins share a double-stranded ß-helix fold, form one of the largest protein superfamilies, and possess remarkable functional diversity. They usually exist in homooligomeric states. Goss and co-workers recently reported that the cupin protein Pac13, which is a dehydratase that mediates the formation of the 3'-deoxy nucleoside of pacidamycins, is an unusual small monomer. However, a careful analysis of the biophysical and structural data provided by the authors suggests that Pac13 is in fact a homodimer, similar to many other cupin proteins.

Structural basis of the mechanism of ß-methyl epimerization by enzyme MarH.

Diverse derivatives of amino acids with different steric configurations are important biosynthetic building blocks. In biology, epimerization is an important way to generate steric diversity. MarH catalyzes the epimerization of the ß-position of (3R)-ß-methyl-indolepyruvate (MeInPy), forming (3S)-ß-MeInPy. Both compounds are derivatives of l-tryptophan (l-Trp) and are important precursors of bioactive natural products. Here, we report the crystal structures of MarH and the NMR structure of its complex with l-Trp, an analogue of its native substrate, (3R)-ß-MeInPy. Structural analysis and mutagenesis studies indicated that His25 acts as a base to remove Hß and generate a planar carbanion intermediate, which is then putatively reprotonated on the opposite face by a water molecule to form (3S)-ß-MeInPy in a stereospecific manner. The details of ß-site isomerization at the atomic level provide deeper insights into the epimerization mechanism of MarH and will facilitate further enzyme design to extend the substrate scope.

Multi-Attribute Fusion Algorithm Based on Improved Evidence Theory and Clustering.

In most of the application scenarios of industrial control systems, the switching threshold of a device, such as a street light system, is typically set to a fixed value. To meet the requirements for a smart city, it is necessary to set a threshold that is adaptive to different conditions by fusing the multi-attribute observations of the sensors. This paper proposes a multi-attribute fusion algorithm based on fuzzy clustering and improved evidence theory. All of the observations are clustered by fuzzy clustering, where a proper clustering method is chosen, and the improved evidence theory is used to fuse the observations. In the experiments, two-dimensional observations for the street light illumination and for the ambient illumination are used in a campus-intelligent lighting system based on a narrowband Internet of things, and the results demonstrate the effectiveness of the proposed fusion algorithm. The proposed algorithm can be applied to a variety of multi-attribute fusion scenarios.

Structural Insights into the Pharmacophore of Vinca Domain Inhibitors of Microtubules.

Antibody-drug conjugates (ADCs) have achieved great success in cancer therapy in recent years. Some peptidyl microtubule inhibitors consisting of natural and unnatural amino acids, such as monomethyl auristatin E (MMAE) and F (MMAF), are extremely cytotoxic and have been used as a payload in ADCs. However, their precise molecular interaction with tubulin and microtubules remains unclear. We determined the crystal structures of tubulin in complex with three ultra-potent peptidyl microtubule inhibitors [MMAE, taltobulin (HTI- 286), and tubulysin M] at 2.5 Å. Our data showed that the three peptides bound to the vinca domain and shared a common and key pharmacophore containing two consecutive hydrophobic groups (Val, Ile-like side chain). These groups protruded in opposite directions into hydrophobic pockets on the tubulin ß and α subunits. Nitrogen and oxygen atoms from the same backbone formed hydrogen bonds with Asn329 from the α subunit and Asp179 from the ß subunit in a direction normal to the surface formed by the aforementioned hydrophobic groups. In addition, our crystal structure data indicated that tubulysin M bound to the ß subunit alone, providing a structural explanation for its higher affinity. We also compared the conformations of two representative structurally different vinca domain compounds, ustiloxin D and vinblastine, with those of the aforementioned peptidyl ligands, and found that they shared a similar pharmacophore. Our findings lay a foundation for the rational design of novel vinca domain ligands and may facilitate the development of microtubule inhibitors with high specificity, affinity, and efficiency as payloads for ADCs in cancer therapy.

Metagenomic investigation of antibiotic resistance genes and resistant bacteria contamination in pharmaceutical plant sites in China.

Pharmaceutical plant sites play a significant role in the dissemination of antibiotic resistance genes (ARGs) into the environment. It is imperative to comprehensively monitor of ARGs across various environmental media at these sites. This study focused on three pharmaceutical plants, two located in North China and one in South China. Through metagenomic approaches, we examined the composition, mobility potential, and bacterial hosts of ARGs in diverse media such as process water, groundwater, topsoil, soil cores, and pharmaceutical fermentation residues across diverse environmental matrices, including topsoil, soil cores, process water, groundwater, and pharmaceutical fermentation residues. We identified a wide array of ARGs, comprising 21 types and 740 subtypes, with process water exhibiting the highest abundance and diversity. Treatment processes varied in their efficacy in eliminating ARGs, and the clinically relevant ARGs should also be considered when evaluating wastewater treatment plant efficiency. Geographical distinctions in groundwater ARG distribution between northern and southern regions were observed. Soil samples from the three sites showed minimal impact from pharmaceutical activity, with vancomycin-resistance genes being the most prevalent. High levels of ARGs in pharmaceutical fermentation residues underscore the necessity for improved waste management practices. Metagenomic assembly revealed that plasmid-mediated ARGs were more abundant than chromosome-mediated ARGs. Metagenome-assembled genomes (MAGs) analysis identified 166 MAGs, with 62 harboring multiple ARGs. Certain bacteria tended to carry specific types of ARGs, revealing distinct host-resistance associations. This study enhances our understanding of ARG dissemination across different environmental media within pharmaceutical plants and underscores the importance of implementing strict regulations for effluent and residue discharge to control ARG spread.

Aerobic granular sludge for swine wastewater treatment: Implications for antibiotic and antibiotic resistance gene elimination.

Swine wastewater (SW) contains high levels of traditional pollutants, antibiotics, and antibiotic resistance genes (ARGs), necessitating effective elimination. Two parallel aerobic granular sludge (AGS) reactors, R1 and R2, were constructed and optimized for treating SW from two pig farms, identified as SW1 and SW2. R2 showed higher antibiotic removal efficiency, particularly in the removal of sulfonamides, while fluoroquinolones tended to adsorb onto the sludge. Process optimization by introducing an additional anoxic phase enhanced denitrification and reduced effluent ARG levels, also aiding in the improved removal of fluoroquinolones. The nitrite-oxidizing bacteria (NOB) Nitrospira accumulated after the treatment process, reaching 12.8 % in R1 and 14.1 % in R2, respectively. Mantel's test revealed that pH, NH4+-N, and Mg significantly affected ARGs and microbial community. Sulfadiazine and sulfamethazine were found to significantly impact ARGs and the microbial communities. This study provides innovative insights into the application of AGS for the treatment of real SW.

Multi-Person 2-D Positioning Method Based on 77 GHz FMCW Radar.

As the world's population ages, technologies that enable long-term non-contact monitoring of patients are of great research significance. For this purpose, we propose a multi-person 2-D positioning method based on a 77 GHz FMCW radar. In this method, we first perform beam scanning processing on the data cube acquired by the radar and obtain the distance-Doppler-angle data cube. Then, we eliminate interfering targets through a multi-channel respiratory spectrum superposition algorithm. Finally, we obtain the distance and angle information of the target by the target center selection method. The experimental results show that the proposed method can detect the distance and angle information of multiple people.

Progress in the Study of Enhanced Heat Exchange in Phase Change Heat Storage Devices.

In comparison with sensible heat storage devices, phase change thermal storage devices have advantages such as high heat storage density, low heat dissipation loss, and good cyclic performance, which have great potential for solving the problem of temporal and spatial imbalances in the transfer and utilization of heat energy. However, there are also issues such as the small thermal conductivity of phase change materials (PCMs) and poor efficiency in heat storage and release, and in recent years, enhanced heat transfer in phase change thermal storage devices has become one of the research hotspots for optimizing thermal storage devices. Although there have been reviews of enhanced heat transfer technology for phase change thermal storage devices in the literature, there is still insufficient research on the summarization of the enhanced heat transfer mechanism, structural optimization, and applications of phase change thermal storage devices. This Review provides a review of enhanced heat transfer in phase change thermal storage devices from two aspects: internal structure enhanced heat transfer and heat exchange medium flow channel enhanced heat transfer. It summarizes the enhanced heat transfer measures of various types of phase change thermal storage devices and discusses the role of structural parameters in enhanced heat transfer. It is hoped that this Review will provide some references for scholars engaged in research on phase change thermal storage heat exchangers.

Mechanism of assembly of snRNP cores assisted by ICln and the SMN complex in fission yeast.

The spliceosomal snRNP cores, each comprised of a snRNA and a seven-membered Sm ring (D1/D2/F/E/G/D3/B), are assembled by twelve chaperoning proteins in human. However, only six assembly-assisting proteins, ICln and the SMN complex (SMN/Gemin2/Gemin6-8), have been found in Schizosaccharomyces pombe (Sp). Here, we used recombinant proteins to reconstitute the chaperone machinery and investigated the roles of these proteins systematically. We found that, like the human system, the assembly in S. pombe requires ICln and the SMN complex sequentially. However, there are several significant differences. For instance, h_F/E/G forms heterohexamers and heterotrimers, while Sp_F/E/G only forms heterohexamers; h_Gemin2 alone can bind D1/D2/F/E/G, but Sp_Gemin2 cannot. Moreover, we found that Sp_Gemin2 is essential using genetic approaches. These mechanistic studies reveal that these six proteins are necessary and sufficient for Sm core assembly at the molecular level, and enrich our understanding of the chaperone systems in species variation and evolution.

Effectiveness and safety of nintedanib in prevention of pulmonary fibrosis induced by bleomycin in malignant ovarian germ cell tumour: study protocol for a randomised, double-blind, placebo-controlled trial.

INTRODUCTION: Bleomycin is a crucial and irreplaceable chemotherapy regimen for malignant ovarian germ cell tumours (MOGCTs) but its toxicities especially pulmonary fibrosis have limited the dose of treatment efficacy and decreased the patients' quality of life (QoL). Nintedanib has been approved for treating progressive fibrosing interstitial lung diseases and has shown potential anti-tumour effects. This study aims to evaluate the effectiveness and safety of nintedanib in the prevention of pulmonary fibrosis induced by bleomycin in MOGCTs patients. METHODS AND ANALYSIS: This is a multicentre, randomised, double-blinded, placebo-controlled clinical trial. We will enrol a total of 128 patients who will be randomly assigned to the nintedanib group and placebo group in a 1:1 ratio. Standard bleomycin, etoposide and cisplatin chemotherapy will be given to each MOGCT patient. In addition, patients assigned to nintedanib and the control group will be given oral nintedanib 150 mg two times per day and placebo one tablet two times per day until 1 month after the last cycle of bleomycin therapy, respectively. The primary outcome is the decline of forced vital capacity (FVC). The secondary outcomes are the decline of other pulmonary function indices (forced expiratory volume in 1 s; FVC pred%, carbon monoxide diffusion capacity) and the patients' QoL, oncological and fertility outcomes. We will use electronic case report forms to record all the participants' data and SPSS V.27.0/STATA V.16.0/Graphpad Prism V.8.0 to conduct statistical analysis. ETHICS AND DISSEMINATION: The Ethics Committee of Peking Union Medical College Hospital has approved the study (I-23PJ400). Written informed consent will be obtained from all participants/guardians. Study results will be submitted to peer-reviewed medical journals for publication and presented at academic conferences. TRIAL REGISTRATION NUMBER: ChiCTR2300070492.

Fast construction of SARS-CoV-2 associated plasmid library using parallel cloning method.

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a significant impact on global health. To address the urgent need for plasmids containing SARS-CoV-2 sequences in research, we have developed a high-throughput FastCloning platform for the construction of associated plasmids. Our platform uses a FastCloning method to construct a plasmid library from 29 ORFs of the virus and 20 commonly used vectors in the lab. The library contains 536 recombinant vectors, with a highly positive clone success rate of 92.4%. Our study provides a rapid and efficient approach to constructing a large plasmid library for SARS-CoV-2 research.

Biotransformation of sulfamonomethoxine in a granular sludge system: Pathways and mechanisms.

The biotransformation of sulfamonomethoxine (SMM) was studied in an aerobic granular sludge (AGS) system to understand the role of sorption by microbial cells and extracellular polymeric substances (EPS) and the role of functional microbe/enzyme biodegradation. Biodegradation played a more important role than adsorption, while microbial cells covered with tightly bound EPS (TB-EPS) showed higher adsorption capacity than microbial cells themselves or microbial cells covered with both loosely bound EPS (LB-EPS) and TB-EPS. The binding tests between EPS and SMM and the spectroscopic analyses (3D-EEM, UV-Vis, and FTIR) were performed to obtain more information about the adsorption process. The data showed that SMM could interact with EPS by combining with aromatic protein compounds, fulvic acid-like substances, protein amide II, and nucleic acids. Batch tests with various substances showed that SMM removal rates were in an order of NH2OH (60.43 ± 2.21 µg/g SS) > NH4Cl (52.96 ± 0.30 µg/g SS) > NaNO3 (31.88 ± 1.20 µg/g SS) > NaNO2 (21.80 ± 0.42 µg/g SS). Hydroxylamine and hydroxylamine oxidoreductase (HAO) favored SMM biotransformation and the hydroxylamine-mediated biotransformation of SMM was more effective than others. In addition, both ammonia monooxygenase (AMO) and CYP450 were able to co-metabolize SMM. Analysis of UPLC-QTOF-MS indicated the biotransformation mechanisms, revealing that acetylation of arylamine, glucuronidation of sulfonamide, deamination, SO2 extrusion, and δ cleavage were the five major transformation pathways. The detection of TP202 in the hydroxylamine-fed Group C indicated a new biotransformation pathway through HAO. This study contributes to a better understanding of the biotransformation of SMM.