SWI/SNF family mutations in advanced NSCLC: genetic characteristics and immune checkpoint inhibitors' therapeutic implication.

BACKGROUND: SWItch/Sucrose NonFermentable (SWI/SNF) mutations have garnered increasing attention because of their association with unfavorable prognosis. However, the genetic landscape of SWI/SNF family mutations in Chinese non-small-cell lung cancer (NSCLC) is poorly understood. In addition, the optimal treatment strategy has not yet been determined. PATIENTS AND METHODS: We collected sequencing data on 2027 lung tumor samples from multiple centers in China to comprehensively analyze the genomic characteristics of the SWI/SNF family within the Chinese NSCLC population. Meanwhile, 519 patients with NSCLC from Sun Yat-sen University Cancer Center were enrolled to investigate the potential implications of immunotherapy on patients with SWI/SNF mutations and to identify beneficial subpopulations. We also validated our findings in multiple publicly available cohorts. RESULTS: Approximately 15% of Chinese patients with lung cancer harbored mutations in the SWI/SNF chromatin remodeling complex, which were mutually exclusive to the EGFR mutations. Patients with SWI/SNFmut NSCLC who received first-line chemoimmunotherapy had better survival outcomes than those who received chemotherapy alone (median progression-free survival: 8.70 versus 6.93 months; P = 0.028). This finding was also confirmed by external validation using the POPLAR/OAK cohort. SWI/SNFmut NSCLC is frequently characterized by high tumor mutational burden and concurrent TP53 or STK11/KEAP mutations. Further analysis indicated that TP53 and STK11/KEAP1 mutations could be stratifying factors in facilitating personalized immunotherapy and guiding patient selection. CONCLUSIONS: This study provides a step forward in understanding the genetic and immunological characterization of SWI/SNF genetic alterations. Moreover, our study reveals substantial benefits of immunotherapy over chemotherapy for SWI/SNF-mutant patients, especially the SWI/SNFmut and TP53mut subgroups.

[The expression and significance of TRPM8 among chronic rhinosinusitis with nasal polyps].

Objective: To compare the expression and difference of melastatin-related transient receptor potential 8(TRPM8) among chronic rhinosinusitis, nasal polyps and normal mucosa tissues. And to explore the significant expression of TRPM8 among CRSwNP. Methods: Fifty-one patients underwent endoscopic sinus surgery in the Department of Otorhinolaryngology Head and Neck Surgery of Renmin Hospital of Wuhan University from February 2019 to January 2020 were recruited, including 33 males and 18 females, aged from 14 to 65 years old (34.55±1.689).Immunohistochemistry was used to detected the expression of TRPM8 protein among CRSsNP(17),CRSwNP (17) and control tissuses(17). In addition, the correlation between the expression of TRPM8 protein in CRSwNP patients and preoperative CT Lund-Mackay scores and preoperative VAS scores and sinonasal outcome test-20 scores was analyzed, respectively. The primary human nasal epithelial cells were cultured in vitro and the expression of TRPM8 was detected by quantitative real-time PCR and western blotting. The tissue in control group, chronic rhinosinusitis without nasal polyps (CRSsNP) group and the CRSwNP group were collected and grinded into tissue homogenized. The expression of TRPM8 protein was detected by western blotting after 24 h stimulation after homogenate was added into the medium of RPMI 2650 and primary nasal epithelial cells. Results: Compared with the control, the expression of TRPM8 was significantly up-regulated in nasal polyps (t=6.852, P<0.05). TRPM8 was mainly expressed in epithelial cells. The expression of TRPM8 in the epithelial cells of CRSsNP had no difference with the control group (t=1.980, P>0.05). In addition, the expression of TRPM8 in CRSwNP patients was positively correlated with the preoperative CT Lund-Mackay scores and VAS scores and SNOT-20 scores (r=0.512, P<0.05;r=0.853, P<0.01;r=0.814, P<0.01). After cultured primary epithelial cells in vitro, the expression level of TRPM8 in epithelial cells derived from nasal polyp was significantly higher than that in control group (t=8.845, P<0.05). By adding the homogenization of control and CRSsNP and CRSwNP tissues, the expression of TRPM8 in RPMI 2650 cells and primary nasal epithelial cells was changed and that was significantly increased after adding the homogenization of the group of CRSwNP. Conclusion: TRPM8 is highly expressed in nasal polyps epithelial cells, suggesting that TRPM8 may be involved in the pathogenesis of nasal polyps regulated by nasal epithelial cells.

[Practice guideline for patients with osteoporosis].

In recent years, osteoporosis (OP) has become one of the main diseases affecting the health of middle-aged and elderly people in China, and the prevalence of OP has increased significantly. The clinical diagnosis and treatment guidelines for this disease are also constantly updated. The overall principles speciallyemphasise that doctors and patients need to work together to negotiate the details of the diagnosis and treatment guidelines, in order to improve the OP clinical diagnosis and treatment rate. Therefore, patients' knowledge of the disease, understanding of clinical guidelines, and cooperation with doctors to implement diagnosis and treatment plans are very important. In this study, from the most concerned issues of the patients, we established the OP patient practice guideline working group. 14 recommendations, as the OP patient practice guidelines, are proposed in accordance with the relevant principles of the "World Health Organization guidelines development manual" and the international normative process.

[Clinical analysis of FRAX in the assessment of fracture risk in patients with rheumatic disease in three medical center].

Objective: The aim is to analyze the fracture risk in rheumatic patients by fracture risk assessment tool (FRAX), which is recommended by World Health Organization (WHO), so that we can prevent the occurrence of osteoporotic fracture earlier. Methods: Totally 617 participants, 204 out-patients with rheumatism, 204 in-patients with rheumatism and 209 healthy controls, from March to October in 2018 of Fourth Medical Center of PLA General Hospital, Jishuitan Hospital and China-Japan Friendship Hospital, were enrolled in this study. The probability of hip fracture (PHF) and major osteoporotic fracture (PMOF) in 10 years with FRAX were compared, and the differences between taking sleroids or not and with or without bone mass density (BMD) of femoral neck were evaluated. Correlation analysis was conducted between PHF, PMOF and clinical information, including age, disease duration, gender, steroid usage, osteocalcin, P1NP and ß-crosslaps. Results: There was no significant difference in PMOF within 10 years (3.455±2.690 vs 2.973±2.149 vs 3.323±1.828) among the three groups (P>0.05), but the PHF (0.986±1.619 vs 0.515±0.873 vs 0.149±0.311) was different (P<0.05). PHF and PMOF increased gradually with age. PMOF of patients without glucocorticoid therapy in 10 years was lower than that of patients with glucocorticoid (3.554±2.584 vs 2.857±2.238, P<0.05). There is no difference between the results of FRAX calculated with BMD or not (3.012±2.231 vs 3.207±2.601, P>0.05). PHF and PMOF were positively correlated with age, course of disease, glucocorticoid use and osteocalcin level, while PHF was negatively correlated with TP1NP among in-patients. Conclusion: The prevalence of 10-year hip fracture calculated by FRAX in rheumatism patients is higher than that of healthy group. FRAX can be used to calculate fracture risk without BMD. Combination of FRAX and bone turnover markers may be more effective in prediction of osteoporotic fracture in rheumatic patients.

[Comparison of disease activities and extent measurements for anti-neutrophil cytoplasmic autoantibody-associated vasculitis].

OBJECTIVE: To investigate the significance of a set of seven disease activities and extension measurements and their correlations between one and another for anti-neutrophil cytoplasmic autoantibody associated vasculitis (AAV). METHODS: A total of 121 patients from Peking University International Hospital and Fouth Medical Center of PLA General Hospital with confirmed diagnoses of AAV clinically were enrolled in the study, including 15 cases of eosinophilic granulomatous with polyangiitis (EGPA), 59 cases of granulomatous with polyangiitis (GPA) and 47 cases of microscopic polyangiitis (MPA). A hundred and twenty-one AAV patients were divided into death group and survival group according to their survival conditions. A set of seven disease assessment scales including Birmingham vasculitis activity score (BVAS)-1994, BVAS-2003, as well as BVAS/GPA, vasculitis damage index (VDI), disease extent index (DEI), five factor score (FFS)-1996, and FFS-2009 were measured and scored one by one, and their relationships which were represented by Spearman correlation coefficient were compared between one and another. RESULTS: BVAS-1994, BVAS-2003, as well as BVAS/GPA, VDI, DEI, and FFS, all of those seven evaluation indexes of the AAV patients in the death group were significantly higher than those in the survival group (P<0.05). Except for BVAS/GPA, all those above indicators in the patients with EGPA were lower than those in the patients with GPA and those in the patients with MPA, and those in all of the AAV patients as a whole group. There were high correlations among BVAS-2003, BVAS-1994 and BVAS/GPA (r values were 0.9 and 0.7, respectively); BVAS-1994 was fairly correlated with BVAS/GPA (r=0.69); FFS-1996 and FFS-2009 were highly correlated (r=0.73) with each other; BVAS-1994, BVAS-2003 and BVAS/GPA were fairly correlated with DEI (with r values of 0.62, 0.65, and 0.62, respectively); VDI was also fairly correlated with BVAS-1994 and with BVAS-2003 (r values were 0.49 and 0.52, respectively). CONCLUSION: All of those seven AAV assessment indicators above can be used as indicators of disease activity and prognosis in AAV patients, most of which were relevant within one and another. There were high correlations among BVAS-2003, BVAS-1994 and BVAS/GPA, and besides, there were also high correlations between FFS-1996 and FFS-2009.

[Comparison of Dengue viral nonstructural protein 1 antigen testing kits].

Objective: To investigate the sensitivity and specificity of commercial nonstructural protein 1 (NS1) testing kits for Dengue fever diagnose, and provide the evidence for diagnostic criteria revision. Methods: 300 PCR or virus isolation positive blood samples for dengue virus were collected from sentinel hospitals for dengue surveillance in Guangzhou, Dongguang and Zhongshang from May 2015 to Nov. 2016. At the same time, 308 PCR negative samples for Dengue virus were collected as control group. The information of the sample was collected using questionnaires. These samples were tested using imported and domestic ELISA and the colloidal gold-labeled kits that were widely used for detecting dengue NS1. Sensitivity, specificity and coincidence were calculated and analyzed, and Z hongshan's result was regarded as the reslut of the third part. Results: The positive group includes 133 males and 167 females, average ages are 47.2±13.3, 179, 110 and 11 of them is Dengue Ⅰ, Ⅱ and Ⅲ respectively. The negative group includes 154 males and 154 females, average ages are (40.1±11.6) years old. The sensitivity of domestic ELISA Kits (94.5%) is less than imported (99.5%), and the result has statistical significance (χ(2)=8.59, P=0.030), the specificity is 99.7% and 97.7% respectively; The sensitivity of imported and domestic the colloidal gold-labeled Kits is 97.5% and 96.5% respectively, both of specificities are 100%. The sensitivity and specificity of Dengue Ⅰ for NS1 test are more than 97.0%. The sensitivity of domestic ELISA and gold-labeled Kits is 90.0% and 95.0%, and the specificity is 96.8% and 100% respectively for Dengue Ⅱ test. The sensitivity of imported ELISA and gold-labeled Kits is 100% and 98.0%, and the specificity is 99.4% and 100% respectively for Dengue Ⅱ test. The result of the third party show the sensitivity and specificity of domestic ELISA and gold-labeled Kits are 90.0% and 98.0%, the differences has statistical significance (χ(2)=5.67, P=0.020). Conclusion: NS1 testing can be used as early dengue fever diagnose for higher sensitivity and specificity.

[Exploration of death risk factors in patients with antineutrophil cytoplasmic antibody associated vasculitis].

Objectives: Death risk factors of patients with antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV) were explored by the analysis of clinical characteristics of AAV patients, as to provide the basis for early diagnosis and treatment, and reduction of mortality and also improvement of prognosis. Methods: A retrospective study was conducted in patients with AAV which were admitted to this hospital from November 2003 to February 2017, by the contrasts of the similarities and differences of clinical characteristics between the death group and non-death group, for explore the risk factors of death. Results: (1) A total of 66 patients with AAV were included in this study, in which 20 were died (male/female was 12/8), and 46 were still alive, with a total mortality rate of 30.3%.(2)The average age of disease onset in the death group was (67±13) years, which was significantly higher than that of the control group (55±18, P=0.009). (3)The mean value of vasculitis damage index (VDI) in the death group was (6.4±2.5), which was significantly higher than that in the non-death group (4.4±2.5, P=0.006). (4)As to multiple organs involvements among the heart, lung, kidney, gastrointestinal tract, central nervous system and other organs, the proportion of three or more organs involvement in the death group was 85% (17/20), which was significantly higher than that in the control group 47.8%(22/46), P=0.004 8.The incidence of heart murmurs, recent premature beats, aortic insufficiency, chronic heart failure/cardiomyopathy, and massive hemoptysis were significantly higher than those in the control group (P<0.05). (5) The incidence of infection in the death group (55%) was significantly higher than that in the control group (28.3%, P=0.038). Conclusion: An onset age of more than 65, multiple organs involvement, especially the occurrence of massive hemoptysis, heart valve diseases, heart failure and other cardiovascular involvements, increased VDI and combination of infections are the risk factors of death in AAV patients.

[The clinical analysis of 46 cases with antineutrophil cytoplasmic antibody-associated vasculitis].

OBJECTIVE: To investigate the clinical features of patients with antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV), and to explore the disease activity of AAV patients and the relationship with prognosis. METHODS: The clinical data of 46 cases of AAV patients in the First Affiliated Hospital of PLA General Hospital were analyzed retrospectively.The clinical and laboratory features of each clinical subtype were compared.The disease activity of AAV and the relationship between disease activity and prognosis were evaluated. RESULTS: Among the 46 patients with AAV, 24 were male, and 22 were female, with the average age of 56±18.Among the subtypes of AAV, the number of granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA) were 22, 17 and 4 respectively, while the positive rate of ANCA are 72.7%, 88.2% and 50.0% respectively.For GPA, the results of ANCA were mainly C-ANCA or ANCA directed toward proteinase-3 (PR3), and for MPA, the results of ANCA were mainly P-ANCA or ANCA directed toward myeloperoxidase (MPO). Upper and lower respiratory disease, renal involvement and non-deformity arthropathy were the common clinical manifestations of all primary AAV subtypes.Epistaxis, nasal blood scab, saddle nose, pulmonary nodule and intrapulmonary cavities were the characteristic manifestations of GPA, while rapid progress of renal failure was prominent in MPA.Whatever their ANCA results, there were no significant differences between each other as to system-organ involvements and laboratory indexes.Seven patients (15.2%) died during hospitalization or in follow-up visits.Serious involvements of heart, lung, kidney, and complicated with infections were the main risk factors of death in AAV patients. CONCLUSIONS: Upper and lower respiratory involvements and kidney diseases are the primary manifestations of AAV patients.ANCA results are irrelevant with disease activity and system-organ involvements.Serious involvements of heart, lung, kidney, and complicated with infections are the main risk factors of death in AAV patients.

Integrative microRNA-mRNA and protein-protein interaction analysis in pancreatic neuroendocrine tumors.

OBJECTIVE: Pancreatic neuroendocrine tumors are relatively rare pancreatic neoplasms over the world. Investigations of the molecular biology of PNETs are insufficient for nowadays. We aimed to explore the expression of microRNA and messenger RNA and regulatory processes underlying pancreatic neuroendocrine tumors. MATERIALS AND METHODS: The messenger RNA and microRNA expression profile of GSE43796 were downloaded, including 6 samples with pancreatic neuroendocrine tumors and 5 healthy samples. First, the Limma package was utilized to distinguish the differentially expressed messenger RNA and microRNA separately. Then we used microRNA Walk databases to predict the target genes of the differentially expressed microRNAs (DE-microRNAs), and selected differentially expressed target genes whose expression was reversely correlated with microRNAs. Gene Ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were performed to explore the functions and pathways of target genes. In addition, we constructed a regulatory miRNAs-target genes network and a protein-protein interaction network. RESULTS: There were 28 differentially expressed microRNAs and 859 differentially expressed messenger RNAs, including 253 potential target genes. These target genes mainly enriched in ABC transporters pathway. In this network, hsa-miR-7-2-3p demonstrated the highest connectivities whereas KLF12 was the mRNAs with the highest connectivities. CXCL12 was identified as the hub of the protein-protein interaction sub-network. CONCLUSIONS: The genes involved in ABC transporters and Type II diabetes mellitus pathway, KLF12 and CXCL12 may play an important role in the progression of pancreatic neuroendocrine tumors. However, more experimental studies are required.

Evaluating the annotation of protein-coding genes in bacterial genomes: Chloroflexus aurantiacus strain J-10-fl and Natrinema sp J7-2 as case studies.

Gene annotation plays a key role in subsequent biochemical and molecular biological studies of various organisms. There are some errors in the original annotation of sequenced genomes because of the lack of sufficient data, and these errors may propagate into other genomes. Therefore, genome annotation must be checked from time to time to evaluate newly accumulated data. In this study, we evaluated the gene density of 2606 bacteria or archaea, and identified 2 with extreme values, the minimum value (Chloroflexus aurantiacus strain J-10-fl) and maximum value (Natrinema sp J7-2), to conduct genome re-annotation. In the genome of C. aurantiacus strain J-10-fl, we identified 17 new genes with definite functions and eliminated 34 non-coding open-reading frames; in the genome of Natrinema sp J7-2, we eliminated 118 non-coding open reading frames. Our re-annotation procedure may provide a reference for improving the annotation of other bacterial genomes.

An epidemiological study of sleep quality in adolescents in South China: a school-based study.

BACKGROUND: This study explored the prevalence of disturbed sleep and investigated its distribution characteristics and associated factors in adolescents in South China. METHODS: Junior middle school and senior high school students (n = 1221) were recruited from schools in Shanghai, China. Students completed a questionnaire using the Pittsburgh Sleep Quality Index and factors associated with disturbed sleep. RESULTS: The prevalence of a tendency towards poor sleep was 34.32% [95% confidence interval (CI): 31.66-36.98] with no significant difference between genders. This tendency increased with age, yielding a significant group effect (P < 0.01). In middle school and high school, the propensity towards poor sleep was 31.34% (95% CI: 28.29-34.39) and 42.22% (95% CI: 36.92-47.52) respectively. The factors associated with poor sleep were more television viewing during weekdays [odds ratio (OR): 1.56, CI: 1.36-1.71], more frequent computer/Internet use (OR: 1.25, CI: 1.08-1.39), earlier school starting time (OR: 1.12, CI: 1.07-1.28), and more time on homework during weekdays (OR: 1.78, CI: 1.51-1.98) and weekends (OR: 1.35, CI: 1.21-1.52) CONCLUSIONS: A tendency towards poor sleep is common in adolescents in South China and its incidence increases with age. The factors associated with this phenomenon indicate that poor sleep in adolescents could be improved, at least partly, by reducing the use of visual technologies and by changing school timetables.

Pitfalls in the management of monaural deafness.

OBJECTIVE: We report a patient who underwent cochlear implantation in an ear with long-term deafness, after an acoustic neuroma had been removed surgically from the other, hitherto good ear and the cochlear nerve had subsequently been resected to relieve severe tinnitus. METHOD: Case report. RESULTS: The patient could not tolerate the cochlear implant, because of a moderate headache due to the stimulation level necessary for environmental sound discrimination. CONCLUSION: Cochlear implantation in patients with long-term deafness should be considered carefully, even if deafness is monaural.

Molecular characterization of the E gene of dengue virus type 1 isolated in Guangdong province, China, in 2006.

We determined the genetic relationships and origin of the dengue virus (DENV) responsible for an outbreak of dengue fever (DF) in Guangdong province, China, in 2006. Five DENV type 1 (DENV-1) isolates were obtained from human serum samples collected from DF patients during the outbreak. The nucleotide sequences of the E (envelope) gene were compared with those of 48 previous DENV-1 isolates: 18 from Guangdong province, one from Fujian province, one from Zhejiang province, and 28 from other countries in the South Asian region. The results suggested that four DENV-1 isolates identified in Guangdong province in 2006 might be in general circulation there, although these DENV-1 viruses may have been originally introduced into the province from other countries. In contrast, one isolate from Guangzhou city in 2006, may have been introduced by a recently imported case from Cambodia.

Magnetic phase transitions in one-dimensional strongly attractive three-component ultracold fermions.

We investigate the nature of trions, pairing, and quantum phase transitions in one-dimensional strongly attractive three-component ultracold fermions in external fields. Exact results for the ground-state energy, critical fields, magnetization and phase diagrams are obtained analytically from the Bethe ansatz solutions. Driven by Zeeman splitting, the system shows exotic phases of trions, bound pairs, a normal Fermi liquid, and four mixtures of these states. Particularly, a smooth phase transition from a trionic phase into a pairing phase occurs as the highest hyperfine level separates from the two lower energy levels. In contrast, there is a smooth phase transition from the trionic phase into a normal Fermi liquid as the lowest level separates from the two higher levels.

Clinical features and outcome of neuropsychiatric lupus in Chinese: analysis of 240 hospitalized patients.

Neuropsychiatric (NP) events are severe manifestations of systemic lupus erythematosus (SLE) and relate to poor outcome. The aims of this study are to investigate the NP manifestations of SLE and to identify the predictive factors for clinical outcome. There was a retrospective review of 240 hospital patients with primary NP events of SLE (NPSLE) from 1990 to 2004. Neuropsychiatric manifestations, SLE disease activity index (SLEDAI) score, System lupus International Collaborating Clinic/American College of Rheumatology Damage Index (SLICC/ACR-DI) score, magnetic resonance imaging (MRI) findings, treatment and mortality rate were included for analysis. From this group of patients, 15 NP syndromes were identified. The most frequent manifestation was headache, followed by seizure. The mean SLEDAI and SLICC/ACR-DI scores were 19.9 +/- 6.9 and 3.5 +/- 1.6, respectively. Abnormal MRI features were found in 67% (61/91) patients. At least one intrathecal (IT) injection of methotrexate (MTX) plus dexamethasone (DXM) was administered to 109 (45.4%) patients. High dose (1 g) intravenous methylprednisolone pulse therapy (IVMP) was administered to 167 (69.5%) patients. Multifactor analysis revealed that high SLICC/ACR-DI scores and sets of concurrent NP symptoms were independently associated with poor outcome, whereas pulse IVMP and IT injection of MTX plus DXM were protective factors against poor outcome. From our data, NPSLE is heterogeneous and is usually associated with high disease activity and organ damage scores. High SLICC/ACR-DI score and having more than two sets of NP symptoms are the predictors for poor outcome, whereas pulse IVMP and IT injection of MTX plus DXM can improve the prognosis.

[Detection of plasma urokinase-type plasminogen activator and its receptor in acute or chronic hepatitis B patients and its clinical significance.].

BACKGROUND: To study the expression of plasma uPA and uPAR in Acute or Chronic Hepatitis B patients, to investigate changes of blood fibrinolytic system in Hepatitis B and its clinical significance. METHODS: The level of detected plasma urokinase-type plasminogen activator (uPA) and urokinase-type plasminogen activator receptor (uPAR) were measured by Enzyme Linked Immuno Sorbent Assay (ELISA). RESULTS: The levels of plasma uPA and uPAR were significantly higher in patients with Acute or Chronic Hepatitis B than that of control group (P less than 0.05, P less than 0.01), and also higher in serious group than that of non-serious group of Chronic Hepatitis B patients (P less than 0.05), and also higher in chronic group than in acute group (P less than 0.05). The level of plasma uPAR was significantly higher in patients with serious jaundice than that of non-serious jaundice group (P less than 0.01). The levels of uPA and uPAR are significantly higher in acute period than that in recover period of Acute Hepatitis B patients, but the levels in recover period is also higher than that in control group. The level of plasma uPAR have positive correlation with prothrombin (PT), international normalized ratio (INR) and total bilirubin (P less than 0.01). CONCLUSION: The level of plasma UPA nad UPAR were enhanced in Acute or Chronic Hepatitis B patients was related with the degree of inflammation, was also related with high expression of serious damage of liver cell. It may be one of important cause to imbalance between coagulation and fibrinolytic in hepatitis.

Studies on the inactivation of bovine liver enoyl-CoA hydratase by (methylenecyclopropyl)formyl-CoA: elucidation of the inactivation mechanism and identification of cysteine-114 as the entrapped nucleophile.

The inhibitory properties of (methylenecyclopropyl)formyl-CoA (MCPF-CoA), a metabolite derived from a natural amino acid, (methylenecyclopropyl)glycine, against bovine liver enoyl-CoA hydratase (ECH) were characterized. We have previously demonstrated that MCPF-CoA specifically targets ECHs, which catalyze the reversible hydration of alpha,beta-unsaturated enoyl-CoA substrates to the corresponding beta-hydroxyacyl-CoA products. Here, we synthesized (R)- and (S)-diastereomers of MCPF-CoA to examine the stereoselectivity of this inactivation. Both compounds were shown to be competent inhibitors for bovine liver ECH with nearly identical second-order inactivation rate constants (k(inact)/K(I)) and partition ratios (k(cat)/k(inact)), indicating that the inactivation is nonstereospecific with respect to ring cleavage. The inhibitor, upon incubation with bovine liver ECH, labels a tryptic peptide, ALGGGXEL, near the active site of the protein, where X is the amino acid that is covalently modified. Cloning and sequence analysis of bovine liver ECH gene revealed the identity of the amino acid residue entrapped by MCPF-CoA as Cys-114 (mature sequence numbering). On the basis of gHMQC (gradient heteronuclear multiple quantum coherence) analysis with [3-(13)C]-labeled MCPF-CoA, the ring cleavage is most likely induced by the nucleophilic attack at the terminal carbon of the exomethylene group (C(2)'). We propose a plausible inactivation mechanism that involves relief of ring strain and is consistent with examples found in the literature. In addition, these studies provide important clues for future design of more efficient and selective inhibitors to control and/or regulate fatty acid metabolism.

Ladder operator for the one-dimensional Hubbard model.

The one-dimensional Hubbard model is integrable in the sense that it has an infinite family of conserved currents. We explicitly construct a ladder operator which can be used to iteratively generate all of the conserved current operators. This construction is different from that used for Lorentz invariant systems such as the Heisenberg model. The Hubbard model is not Lorentz invariant, due to the separation of spin and charge excitations. The ladder operator is obtained by a very general formalism which is applicable to any model that can be derived from a solution of the Yang-Baxter equation.