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1.
Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi ; 41(11): 801-807, 2023 Nov 20.
Artigo em Zh | MEDLINE | ID: mdl-38073205

RESUMO

Objective: To explore the mechanism of osteoclast stimulatory transmembrane protein (OC-STAMP) overexpression on epithelial-mesenchymal transition (EMT) . Methods: In April 2021, mice alveolar type Ⅱ epithelial cells MLE-12 were divided into five groups: overexpression control group (NC group), Ocstamp overexpression group (over-Ocstamp group), Fasudil intervention group (over-Ocstamp+Fasudil group), silence control group (si-NC group), Ocstamp silence group (si-Ocstamp group). The protein expressions of OC-STAMP, epithelial marker protein-E-cadherin (E-cad), interstitial marker protein-α-smooth muscle actin (α-SMA), Ras homolog gene family member A (RhoA), Rho GDP dissociation inhibitor α (Rho GDIα), Rho-associated protein kinase (ROCK), phosphate myosin phosphatase (p-MYPT) were examined by Western blotting and Immunocytochemical staining. The filamentous actin (F-actin) was detected by Phalloidin method. t test was used to compare the relative expression of each protein between the two groups. Results: Western blotting and Immunocytochemical staining showed that compared with the NC group, the expression level of E-cad was down-regulated, while the expression levels of α-SMA, Rho GDIα, RhoA, ROCK, p-MYPT were increased, and F-actin expression was enhanced in the over-Ocstamp group. The differences were statistically significant (P<0.05). There were no significant differences in E-cad and α-SMA protein expression in si-Ocstamp group compared with si-NC group (P>0.05). Compared with over-Ocstamp group, the expression level of E-cad protein in over-Ocstamp+Fasudil group was up-regulated, the expression levels of α-SMA, Rho GDIα, RhoA, ROCK and p-MYPT protein were decreased, and F-actin expression was weakened, with statistical significance (P<0.05) . Conclusion: OC-STAMP overexpression in alveolar type Ⅱ epithelial cells may induce actin cytoskeleton remodeling through activation of Rho GDIα/RhoA/ROCK signaling pathway, thus promoting EMT.


Assuntos
Actinas , Inibidor alfa de Dissociação do Nucleotídeo Guanina rho , Camundongos , Animais , Actinas/metabolismo , Inibidor alfa de Dissociação do Nucleotídeo Guanina rho/metabolismo , Transição Epitelial-Mesenquimal , Quinases Associadas a rho/metabolismo , Citoesqueleto de Actina/metabolismo , Células Epiteliais/metabolismo
2.
Scand J Immunol ; 87(2): 63-72, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29193199

RESUMO

DNA vaccination is a promising cancer treatment due to its safety, but poor immunogenicity limits its application. However, immunoadjuvants, heterogeneous prime-boost strategies and combination with conventional treatments can be used to improve the antitumour immune effects. A CpG motif and interleukin-2 (IL-2) cytokine are often used as adjuvants. In this study, a DNA vaccine containing a CpG motif was constructed to evaluate its adjuvant effect. The results show that the cytotoxicity of the DNA vaccine was increased fivefold, and survival lifetime was prolonged twofold by the CpG motif adjuvant. To simplify the industrial production process, a bicistronic plasmid was constructed to carry the fusion genes of survivin/MUC1 (MS) and IL-2 and with a CpG motif in its backbone. The results showed that the antitumour effect of the bicistronic vaccine was the same as that of the two vaccine co-injected regime. Furthermore, the vaccine could suppress metastatic tumour foci by 69.1% in colorectal carcinoma-bearing mice. Moreover, the vaccine induced survivin- and MUC1-specific immune responses in splenocytes and induced the immune promoting factor CCL-19 and GM-CSF upregulated, while metastatic-associated factor MMP-9 and immunosuppressing factor PD-L1 downregulated in tumour tissue. When combining the vaccine with the chemotherapy drug oxaliplatin, the survival was prolonged by about 2.5-fold. In conclusion, the DNA vaccine containing a CpG motif in bicistronic form showed good effects on colorectal cancer by inhibiting both tumour growth and metastasis, and combination with oxaliplatin could improve its antitumour effects.


Assuntos
Adjuvantes Imunológicos/genética , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Vacinas Anticâncer/imunologia , Neoplasias Colorretais/imunologia , Proteínas Inibidoras de Apoptose/genética , Mucina-1/genética , Oligodesoxirribonucleotídeos/genética , Compostos Organoplatínicos/uso terapêutico , Proteínas Repressoras/genética , Vacinas de DNA/imunologia , Animais , Vacinas Anticâncer/genética , Processos de Crescimento Celular , Linhagem Celular Tumoral , Neoplasias Colorretais/terapia , Modelos Animais de Doenças , Feminino , Genes/genética , Humanos , Imunidade , Interleucina-2/administração & dosagem , Interleucina-2/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Metástase Neoplásica , Oxaliplatina , Plasmídeos , Survivina , Vacinas de DNA/genética
4.
Zhonghua Fu Chan Ke Za Zhi ; 52(10): 662-668, 2017 Oct 25.
Artigo em Zh | MEDLINE | ID: mdl-29060963

RESUMO

Objectives: To analyze 3 cases of 17q12 microdeletion syndrome diagnosed prenatally, and to demonstrate clinical phenotype of the syndrome in prenatal setting. Methods: From January 2013 to July 2017, 1 370 women received invasive prenatal diagnosis and chromosome microarray analysis (CMA) in Peking Union Medical College Hospital. Among them, 3 fetuses were diagnosed as 17q12 microdeletion syndrome. All 3 cases were low-risk pregnancies. Abnormal structures in fetal kidney were found in all 3 cases, including 1 case of multiple renal cysts, 2 cases of bilateral hyperechogenic kidneys. These women accepted invasive prenatal diagnosis followed by karyotyping, parental fluorescence in situ hybridization or CMA validation. Results: The second and third trimester ultrasound showed that all 3 fetuses had bilateral renal structural abnormalities, including hyperechogenic kidney, multiple cysts and renal pelvis dilatation. The karyotyping of the 3 fetuses were normal. CMA examination showed that each case had 1.4-1.6 Mb deletion in 17q12 region. Two cases were de novo deletion and 1 case was inherited from the mother who had mild symptoms. The 3 women decided to terminate pregnancies after genetic counseling. Conclusion: 17q12 microdeletion syndrome is a recurrent chromosome microdeletion syndrome, and the unique phenotype in prenatal setting is the abnormal structure of bilateral kidneys. A few cases of 17q12 microdeletion syndrome even inherited normally phenotypical parents, and prenatal genetic counseling of 17q12 microdeletion syndrome is relatively difficult.


Assuntos
Anormalidades Múltiplas/diagnóstico por imagem , Doenças Fetais/genética , Deficiência Intelectual/diagnóstico por imagem , Rim/diagnóstico por imagem , Diagnóstico Pré-Natal , Ultrassonografia Pré-Natal , Anormalidades Múltiplas/genética , Deleção Cromossômica , Cromossomos Humanos Par 17/genética , Feminino , Doenças Fetais/diagnóstico por imagem , Humanos , Hibridização in Situ Fluorescente , Deficiência Intelectual/genética , Cariotipagem , Análise em Microsséries , Fenótipo , Gravidez
5.
Psychol Med ; 46(1): 125-35, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26315390

RESUMO

BACKGROUND: Dysregulation of the striatum and altered corticostriatal connectivity have been associated with psychotic disorders. Social anhedonia has been identified as a predictor for the development of schizophrenia spectrum disorders. The aim of the present study was to examine corticostriatal functional connectivity in individuals with high social anhedonia. METHOD: Twenty-one participants with high social anhedonia score and 30 with low social anhedonia score measured by the Chinese version of the Revised Social Anhedonia Scale were recruited from university undergraduates (age 17-21 years) to undergo resting-state functional MRI scans. Six subdivisions of the striatum in each hemisphere were defined as seeds. Voxel-wise functional connectivity analyses were conducted between each seed and the whole brain voxels, followed by repeated-measures ANOVA for the group effect. RESULTS: Participants with high social anhedonia showed hyper-connectivity between the ventral striatum and the anterior cingulate cortex and the insula, and between the dorsal striatum and the motor cortex. Hypo-connectivity in participants with high social anhedonia was also observed between the ventral striatum and the posterior cingulate cortex. Partial correlation analyses further showed that the functional connectivity between the ventral striatum and the prefrontal cortex was associated with pleasure experience and emotional suppression. CONCLUSIONS: Our findings suggest that altered corticostriatal connectivity can be found in participants with high levels of social anhedonia. Since social anhedonia has been considered a predictor for schizophrenia spectrum disorders, our results may provide novel evidence on the early changes in brain functional connectivity in at-risk individuals.


Assuntos
Anedonia/fisiologia , Córtex Cerebral/fisiopatologia , Corpo Estriado/fisiopatologia , Lobo Frontal/fisiopatologia , Relações Interpessoais , Adolescente , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Adulto Jovem
6.
Psychol Med ; 46(2): 437-47, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26464039

RESUMO

BACKGROUND: Patients with schizophrenia have intact ability to experience emotion, but empirical evidence suggests that they fail to translate emotional salience into effortful behaviour. Previous research in patients with chronic schizophrenia suggests that working memory is important in integrating emotion and behaviour. This study aimed to examine avolition and anhedonia in patients with first-episode schizophrenia and clarify the role of working memory in emotion-behaviour coupling. METHOD: We recruited 72 participants with first-episode schizophrenia and 61 healthy controls, and used a validated emotion-inducing behavioural paradigm to measure participants' affective experiences and how experienced emotion coupled with behaviour. Participants were given the opportunity to expend effort to increase or decrease their exposure to emotion-inducing photographs. Participants with schizophrenia having poor working memory were compared with those with intact working memory in their liking and emotion-behaviour coupling. RESULTS: Patients with first-episode schizophrenia experienced intact 'in-the-moment' emotion, but their emotion was less predictive of the effort expended, compared with controls. The emotion-behaviour coupling was significantly weaker in patients with schizophrenia with poor working memory than in those with intact working memory. However, compared with controls, patients with intact working also showed substantial emotion-behaviour decoupling. CONCLUSIONS: Our findings provide strong evidence for emotion-behaviour decoupling in first-episode schizophrenia. Although working memory deficits contribute to defective translation of liking into effortful behaviour, schizophrenia alone affects emotion-behaviour coupling.


Assuntos
Anedonia , Transtornos Cognitivos/psicologia , Transtornos da Memória/psicologia , Memória de Curto Prazo , Esquizofrenia , Psicologia do Esquizofrênico , Adulto , Estudos de Casos e Controles , Emoções , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Adulto Jovem
7.
Pulmonology ; 29(6): 495-504, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37210334

RESUMO

BACKGROUND: Gender disparity in authorship broadly persists in medical literature, little is known about female authorship within pulmonary medicine. METHODS: A bibliometric analysis of publications from 2012 to 2021 in 12 journals with the highest impact in pulmonary medicine was conducted. Only original research and review articles were included. Names of the first and last authors were extracted and their genders were identified using the Gender-API web. Female authorship was described by overall distribution and distribution by country/region/continent and journal. We compared the article citations by gender combinations, evaluated the trend in female authorship, and forecasted when parity for first and last authorship would be reached. We also conducted a systematic review of female authorship in clinical medicine. RESULTS: 14,875 articles were included, and the overall percentage of female first authors was higher than last authors (37.0% vs 22.2%, p<0.001). Asia had the lowest percentage of female first (27.6%) and last (15.2%) authors. The percentages of female first and last authors increased slightly over time, except for a rapid increase in the COVID-19 pandemic periods. Parity was predicted in 2046 for the first authors and 2059 for the last authors. Articles with male authors were cited more than articles with female authors. However, male-male collaborations significantly decreased, whereas female-female collaborations significantly increased. CONCLUSIONS: Despite the slow improvement in female authorship over the past decade, there is still a substantial gender disparity in female first and last authorship in high-impact medical journals in pulmonary medicine.


Assuntos
Autoria , Pneumologia , Humanos , Masculino , Feminino , Equidade de Gênero , Pandemias , Bibliometria
8.
Genet Mol Res ; 11(3): 2569-77, 2012 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-22843074

RESUMO

DNA methylation is essential for adipose deposition in mammals. We screened SNPs of the bovine DNA methyltransferase 3b (DNMT3b) gene in Snow Dragon beef, a commercial beef cattle population in China. Nine SNPs were found in the population and three of six novel SNPs were chosen for genotyping and analyzing a possible association with 16 meat quality traits. The frequencies of the alleles and genotypes of the three SNPs in Snow Dragon beef were similar to those in their terminal-paternal breed, Wagyu. Association analysis disclosed that SNP1 was not associated with any of the traits; SNP2 was significantly associated with lean meat color score and chuck short rib score, and SNP3 had a significant effect on dressing percentage and back-fat thickness in the beef population. The individuals with genotype GG for SNP2 had a 25.7% increase in lean meat color score and a 146% increase in chuck short rib score, compared with genotype AA. The cattle with genotype AG for SNP3 had 35.7 and 24% increases in dressing percentage and 28.8 and 29.2% increases in back-fat thickness, compared with genotypes GG and AA, respectively. Genotypic combination analysis revealed significant interactions between SNP1 and SNP2 and between SNP2 and SNP3 for the traits rib-eye area and live weight. We conclude that there is considerable evidence that DNMT3b is a determiner of beef quality traits.


Assuntos
Bovinos/genética , DNA (Citosina-5-)-Metiltransferases/genética , Estudos de Associação Genética , Carne , Polimorfismo de Nucleotídeo Único/genética , Característica Quantitativa Herdável , Animais , Sequência de Bases , Cruzamento , Frequência do Gene/genética , Genótipo , Dados de Sequência Molecular , DNA Metiltransferase 3B
9.
Poult Sci ; 91(3): 739-43, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22334751

RESUMO

The aim of this research was to study S-ovalbumin as a reference index for the freshness of commercial shell eggs in terms of equivalent egg age. The S-ovalbumin content, yolk index, albumen pH, and Haugh units were determined at the storage temperature of 25 and 37°C, respectively, using 85 fresh-laid eggs. A correlation analysis showed a high correlation coefficient of S-ovalbumin content to storage time as well as to the 3 frequently used freshness indices (Haugh unit, yolk index, and albumen pH). Furthermore, a prediction model of equivalent egg age at 25°C was established using S-ovalbumin content as an index on the basis of the correlation analysis. This study confirmed the possibility of using S-ovalbumin as a reference index to express commercial shell egg freshness as equivalent egg age.


Assuntos
Ovos/normas , Ovalbumina/análise , Animais , Galinhas , Cinética
10.
J Clin Pharm Ther ; 36(5): 614-24, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21916909

RESUMO

WHAT IS KNOWN AND OBJECTIVE: Tacrolimus (TAC) is metabolized mainly by the CYP3A subfamily and extruded into the intestine by P-glycoprotein, which is encoded by the ABCB1 gene. Several studies have suggested that the CYP3A5*3 genotype influenced the pharmacokinetics (PK) of TAC. The CYP3A4*18B and CYP3A5*3 alleles are clinically important in Chinese subjects because of their relatively high frequency. The present study aimed at evaluating the effects of ABCB1 (C1236T-G2677T/A-C3435T), CYP3A4*18B and CYP3A5*3 genetic polymorphisms on TAC PK in healthy Chinese subjects. METHODS: Data were obtained from a comparative bioavailability study of oral TAC formulations (n = 22). TAC whole blood concentrations were measured by LC-MS/MS. Genetic polymorphisms were determined using a direct sequencing method. Nonlinear mixed-effects modelling (NONMEM) was performed to assess the effect of genotypes and demographics on TAC PKs. RESULTS AND DISCUSSION: Both CYP3A4*18B and CYP3A5*3 polymorphisms affected the TAC PK, whereas ABCB1 genetic polymorphisms and other demographic characteristics did not. The combined genotypes of CYP3A4*18B and CYP3A5*3 had a greater impact than either genotype alone, and they were estimated to account for 28·4% of the inter-subject variability of apparent clearance (CL/F) by NONMEM. The CL/F in subjects with CYP3A4*1/*1-CYP3A5*3/*3 was 10·3 L/h and was 48·5% in those not carrying CYP3A4*1/*1-CYP3A5*3/*3. WHAT IS NEW AND CONCLUSION: This is the first study to extensively explore the influence of CYP3A4*18B, CYP3A5*3 and ABCB1 genetic polymorphisms on TAC PK in healthy Chinese subjects. The results demonstrated that subjects with a combined genotype of CYP3A4*1/*1-CYP3A5*3/*3 may require lower TAC doses to achieve target concentration levels and further investigation is needed in larger populations to confirm the clinical benefits.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Citocromo P-450 CYP3A/genética , Genética Populacional/métodos , Imunossupressores/farmacocinética , Transplante de Rim , Tacrolimo/farmacocinética , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Adulto , Povo Asiático/genética , Estudos Cross-Over , Citocromo P-450 CYP3A/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Demografia , Feminino , Frequência do Gene , Genética Populacional/estatística & dados numéricos , Humanos , Imunossupressores/sangue , Imunossupressores/farmacologia , Rim/fisiopatologia , Masculino , Modelos Biológicos , Polimorfismo Genético , Polimorfismo de Nucleotídeo Único , Distribuição Aleatória , Reprodutibilidade dos Testes , Tacrolimo/sangue , Tacrolimo/farmacologia , Adulto Jovem
11.
J Mater Sci Mater Med ; 20(5): 1149-57, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19132512

RESUMO

Biodegradable and bioactive beta-tricalcium phosphate (beta-TCP) coatings were prepared on magnesium (Mg) in order to improve its biocompatibility by a chemical method. The tensile bonding strength of beta-TCP coating and Mg substrate was measured by the standard adhesion test (ISO 13779-4). And the cytocompatibility of beta-TCP coated Mg was studied by using human osteoblast-like MG63 cells. It was found that the MG63 cells could grow well on the surface of beta-TCP coated Mg and the cell viability on beta-TCP coated Mg was above 80% during the cocultivation of MG63 cells and beta-TCP coated Mg for 10 days, indicating no cytotoxicity. It was concluded that the beta-TCP coated Mg had good cytocompatibility. The degradation of Mg substrate with beta-TCP coating in vitro was studied in detail by XRD, EDX, SEM, and ICP. The results showed that a bone-like apatite continually formed on the surface of the sample with the degradation of both Mg substrate and beta-TCP coating in Hank's solution (a simulated body fluid). The biodegradation mechanism was preliminarily analyzed in the paper.


Assuntos
Fosfatos de Cálcio/isolamento & purificação , Materiais Revestidos Biocompatíveis/química , Magnésio/química , Substitutos Ósseos/química , Fosfatos de Cálcio/farmacocinética , Fosfatos de Cálcio/toxicidade , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica de Varredura , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Resistência à Tração , Difração de Raios X
12.
Research (Wash D C) ; 2019: 9854593, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31549098

RESUMO

A contactless label-free method using a diamagnetophoretic ink to rapidly print three-dimensional (3D) scaffold-free multicellular structures is described. The inks consist of MCF-7 cells that are suspended in a culture medium to which a paramagnetic salt, diethylenetriaminepentaacetic acid gadolinium (III) dihydrogen salt hydrate (Gd-DTPA), is added. When a magnetic field is applied, the host fluid containing the paramagnetic salt is attracted towards regions of high magnetic field gradient, displacing the ink towards regions with a low gradient. Using this method, 3D structures are printed on ultra-low attachment (ULA) surfaces. On a tissue culture treated (TCT) surface, a 3D printed spheroid coexists with a two-dimensional (2D) cell monolayer, where the composite is termed as a 2.5D structure. The 3D structures can be magnetically printed within 6 hours in a medium containing 25 mM Gd-DTPA. The influence of the paramagnetic salt on MCF-7 cell viability, cell morphology, and ability of cells to adhere to each other to stabilize the printed structures on both ULA and TCT surfaces is investigated. Gene expressions of hypoxia-inducible factor 1-alpha (HIF1α) and vascular endothelial growth factor (VEGF) allow comparison of the relative stresses for the printed 3D and 2.5D cell geometries with those for 3D spheroids formed without magnetic assistance. This magnetic printing method can be potentially scaled to a higher throughput to rapidly print cells into 3D heterogeneous cell structures with variable geometries with repeatable dimensions for applications such as tissue engineering and tumour formation for drug discovery.

13.
Mol Cell Biol ; 21(13): 4311-20, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11390659

RESUMO

Snf-Swi, the prototypical ATP-dependent nucleosome-remodeling complex, regulates transcription of a subset of yeast genes. With the exception of Snf2p, the ATPase subunit, the functions of the other components are unknown. We have investigated the role of the conserved Snf-Swi core subunit Snf5p through characterization of two conditional snf5 mutants. The mutants contain single amino acid alterations of invariant or conserved residues that abolish Snf-Swi-dependent transcription by distinct mechanisms. One mutation impairs Snf-Swi assembly and, consequently, its stable association with a target promoter. The other blocks a postrecruitment catalytic remodeling step. These findings suggest that Snf5p coordinates the assembly and nucleosome-remodeling activities of Snf-Swi.


Assuntos
Cromatina/metabolismo , Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Saccharomyces cerevisiae/genética , Fatores de Transcrição/metabolismo , Trifosfato de Adenosina/metabolismo , Alelos , Motivos de Aminoácidos , Cromatina/genética , Proteínas Cromossômicas não Histona , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Genes Reporter/genética , Glucose/farmacologia , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Humanos , Immunoblotting , Substâncias Macromoleculares , Nucleossomos/genética , Nucleossomos/metabolismo , Regiões Promotoras Genéticas , Ligação Proteica/efeitos dos fármacos , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Sequências Reguladoras de Ácido Nucleico/genética , Proteína SMARCB1 , Proteínas de Saccharomyces cerevisiae , Temperatura , Fatores de Transcrição/química , Fatores de Transcrição/genética , Transcrição Gênica/genética , beta-Frutofuranosidase
14.
Org Lett ; 1(7): 1111-3, 1999 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-10825963

RESUMO

[formula: see text] Lewis acid-catalyzed reaction of allyl and benzyl trichloroacetimidates with alpha-silyl alcohols was found to be a general method for the synthesis of alpha-alkoxysilanes. Upon exposure to CsF, these alpha-alkoxysilanes could be made to undergo [2,3]-Wittig rearrangement with an efficiency similar to that realized by the analogous but inherently more toxic alpha-alkoxystannanes.


Assuntos
Silanos/síntese química , Silanos/química
15.
Org Lett ; 1(7): 1115-8, 1999 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-10825964

RESUMO

[formula: see text] The Wittig rearrangements of alpha-alkoxysilanes, promoted by the action of methyllithium were studied. Depending on both the substrate and reaction conditions employed, [2,3]-, [1,2]-, or [1,4]-Wittig rearrangements can be realized. These rearrangements were shown to be initiated by either Si/Li exchange or deprotonation alpha to the silane. Furthermore the sigmatropic shifts can often be followed by other synthetically useful in situ chemical events.


Assuntos
Alcanos/química , Lítio/química , Silanos/química
16.
Int J Biol Macromol ; 23(3): 199-206, 1998 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9777707

RESUMO

To further understand the folding of nascent peptide during the early course of peptide synthesis, two short N-terminal fragments of staphylococcal nuclease R (SNase R), SNR52 and SNR79, were made by deleting 97 and 70 amino acid residues from the C-terminus. The conformations of SNR52 and SNR79 were studied by FTIR and far-ultraviolet CD. The results demonstrate that even the short N-terminal fragments of SNase R still have a certain amount of residual ordered secondary structure in the physiological condition. The ordered secondary structures were mainly assigned as beta-strands and turns, which corresponds well to the structures of the N-terminal part in the native protein. The conformational changes during unfolding and refolding in different concentrations of guanidine hydrochloride (GuHCl), monitored by far-ultraviolet CD and intrinsic fluorescence, show that the interaction between amino acid residues, which governs the formation of their conformation are not random. Considered together with earlier studies (Jing et al., Biochim Biophys Acta 1995;1250:189-196; Zhou et al., J Biochem 1996:120: 881-888), the results suggest that the folding of nascent peptide chains begins early in the synthesis process and that the amount of ordered structure increases with increasing peptide chain length until the conformation of the biologically active protein is generated.


Assuntos
Nuclease do Micrococo/biossíntese , Nuclease do Micrococo/química , Fragmentos de Peptídeos/química , Dobramento de Proteína , Dicroísmo Circular , Guanidina/química , Fragmentos de Peptídeos/metabolismo , Conformação Proteica , Desnaturação Proteica , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
17.
Artigo em Inglês | MEDLINE | ID: mdl-19198065

RESUMO

Regulation of transcription is a critically important process that controls development, differentiation, and the maintenance of cellular homeostasis. Cells have evolved numerous mechanisms to keep gene transcription tightly in check, some of which involve the ubiquitin-proteasome system. In this chapter, we review evidence supporting the concept that ubiquitin and the proteasome not only control transcription, but provide the biochemical means to drive key steps in the transcription process forward.


Assuntos
Complexo de Endopeptidases do Proteassoma/metabolismo , Transcrição Gênica/genética , Ubiquitina/metabolismo , Animais , Humanos , Neoplasias/genética , Neoplasias/metabolismo , Complexo de Endopeptidases do Proteassoma/genética , Fatores de Transcrição/metabolismo , Ubiquitina/genética
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