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1.
Rev Sci Instrum ; 93(4): 043906, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35489900

RESUMO

The knowledge of high-pressure behavior of LiH is significant for the validation of fundamental theoretical models and applications in thermonuclear materials and potential energy supplies. The compressibility of 7LiH under isentropic compression at high pressure was investigated experimentally and theoretically. The experimental technique for quasi-isentropic compression with low-density materials was developed using the magnetocumulative generator CJ-100 and x-ray flash radiography. The x-ray images and extracted interface of the sample target in dynamic flash radiography experiments were obtained. According to each interface size of the target both before and after compression, the compression ratio of 7LiH and reference material aluminum was obtained. The density of the reference and using its known isentropic curve provide the pressure in the reference. The pressure in 7LiH was deduced from the pressure in the reference and using the calculated gradient correction factor. The quasi-isentropic data point at 438 GPa was obtained experimentally. A semiempirical three-term complete equation of state was constructed and validated for 7LiH using the theory of Mie-Grüneisen-Debye with experimental data from the literature. The quasi-isentrope data point is reasonably consistent with the theoretical results. The quasi-isentropic experimental techniques and results broaden the existing research scope and are practical and helpful to further validate theoretical models in the future.

2.
Support Care Cancer ; 26(5): 1617-1624, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29209834

RESUMO

PURPOSE: This study aimed, firstly, to assess the determinants of return to work (RTW), secondly, to explore the amount of annual wage loss, and finally, to discover the determinants of wage loss among breast cancer (BC) survivors. METHODS: A cross-sectional study design was used in this research. The data was collected via interview using a validated questionnaire. Logistic regression models were developed to discover the significant determinants of RTW and of wage loss among BC survivors. RESULTS: A total of 256 BC survivors were included in this study. The analysis showed that there was a 21% loss of or reduction in mean income within 1 year after diagnosis. The significant predictors of RTW are being a government employee, having reduced wages or wage loss, and if the case had been diagnosed 1 year or more ago. Being a private sector employee and having a late stage of cancer was a barrier to RTW. The main risk factors for reduced wages or wage loss were belonging to the age group of 40-59 years, being of Chinese or Indian ethnicity, having low educational status, and not returning to work. However, belonging to the higher monthly income group (earning > RM 2000) is a protective factor against the risk of reduced wages or wage loss. CONCLUSIONS: Non-RTW and wage loss after diagnosis of BC may result in the survivors experiencing a significant financial burden. Assessment of these patients is becoming more crucial because more women participate in the workforce in Malaysia nowadays and because BC is managed using multiple treatment modalities with their consequences could lead to long absences from work.


Assuntos
Sobreviventes de Câncer/psicologia , Retorno ao Trabalho/economia , Retorno ao Trabalho/psicologia , Salários e Benefícios/economia , Adulto , Idoso , Estudos Transversais , Feminino , Humanos , Malásia , Masculino , Pessoa de Meia-Idade , Retorno ao Trabalho/estatística & dados numéricos , Inquéritos e Questionários , Adulto Jovem
3.
Ann Oncol ; 28(10): 2443-2450, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28945850

RESUMO

BACKGROUND: Icotinib has been previously shown to be non-inferior to gefitinib in non-selected advanced non-small-cell lung cancer patients when given as second- or further-line treatment. In this open-label, randomized, phase 3 CONVINCE trial, we assessed the efficacy and safety of first-line icotinib versus cisplatin/pemetrexed plus pemetrexed maintenance in lung adenocarcinoma patients with epidermal growth factor receptor (EGFR) mutation. PATIENTS AND METHODS: Eligible participants were adults with stage IIIB/IV lung adenocarcinoma and exon 19/21 EGFR mutations. Participants were randomly allocated (1 : 1) to receive oral icotinib or 3-week cycle of cisplatin plus pemetrexed for up to four cycles; non-progressive patients after four cycles were maintained with pemetrexed until disease progression or intolerable toxicity. The primary end point was progression-free survival (PFS) assessed by independent response evaluation committee. Other end points included overall survival (OS) and safety. RESULTS: Between January 2013 and August 2014, 296 patients were randomized, and 285 patients were treated (148 to icotinib, 137 to chemotherapy). Independent response evaluation committee-assessed PFS was significantly longer in the icotinib group (11.2 versus 7.9 months; hazard ratio, 0.61, 95% confidence interval 0.43-0.87; P = 0.006). No significant difference for OS was observed between treatments in the overall population or in EGFR-mutated subgroups (exon 19 Del/21 L858R). The most common grade 3 or 4 adverse events (AEs) in the icotinib group were rash (14.8%) and diarrhea (7.4%), compared with nausea (45.9%), vomiting (29.2%), and neutropenia (10.9%) in the chemotherapy group. AEs (79.1% versus 94.2%; P < 0.001) and treatment-related AEs (54.1% versus 90.5%; P < 0.001) were significantly fewer in the icotinib group than in the chemotherapy group. CONCLUSIONS: First-line icotinib significantly improves PFS of advanced lung adenocarcinoma patients with EGFR mutation with a tolerable and manageable safety profile. Icotinib should be considered as a first-line treatment for this patient population.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Éteres de Coroa/uso terapêutico , Receptores ErbB/genética , Neoplasias Pulmonares/tratamento farmacológico , Quinazolinas/uso terapêutico , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Cisplatino/administração & dosagem , Cisplatino/efeitos adversos , Éteres de Coroa/efeitos adversos , Receptores ErbB/metabolismo , Éxons , Feminino , Humanos , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Quimioterapia de Manutenção , Masculino , Pessoa de Meia-Idade , Mutação , Estadiamento de Neoplasias , Pemetrexede/administração & dosagem , Pemetrexede/efeitos adversos , Quinazolinas/efeitos adversos
4.
Zhonghua Yi Xue Za Zhi ; 96(27): 2176-8, 2016 Jul 19.
Artigo em Chinês | MEDLINE | ID: mdl-27464545

RESUMO

OBJECTIVE: To investigate the incidence, occurrence time and types of aphakic glaucoma following infantile congenital cataract surgery. METHODS: The records of children who underwent surgery for congenital cataract within the first 24 months of life between January 2010 and January 2014 at the First Affiliated Hospital of Zhengzhou University were retrospectively reviewed.Children with preoperative conditions associated with glaucoma were excluded.The following parameters were ascertained: age received cataract surgery, operation method, the incidence, occurrence time and types of glaucoma. RESULTS: A total of 205 patients (324 eyes) with an average surgery age of 13.9 months were included, and the mean follow-up time was 47.6 months.The operation method was cataract extraction combined with posterior continuous circular capsulorhexis and anterior vitrectomy.Twenty-nine patients (37 eyes, 11.42%) had subsequent development of aphakic glaucoma, 9 eyes of which (2.78%) developed early onset angle closed glaucoma, and the occurrence time was (4.2±2.6) months after cataract surgery; 28 eyes (8.64%) developed late onset open angle glaucoma, 26 of which was angle open glaucoma, and the rest two was angle closed glaucoma.The occurrence time was (37.5±11.0) months after cataract surgery. Twenty-nine patients (37 eyes) developed aphakic glaucoma had cataract surgery within 2 to 12 months (6.8 months on average). The rest 176 patients (287 eyes) who did not develop glaucoma had cataract surgery at 10 to 24 months (14.1 months on average). CONCLUSIONS: The incidence of aphakic glaucoma following infantile congenital cataract surgery is 11.42%.Aphakic glaucoma is divided into two types of early onset angle closed glaucoma and late onset open angle glaucoma.The occurence time of glaucoma was 2 months to 64 months after cataract surgery.Late onset open angle glaucoma is the most common type.


Assuntos
Extração de Catarata , Glaucoma , Catarata , Olho , Glaucoma de Ângulo Aberto , Hospitais , Humanos , Incidência , Lactente , Estudos Retrospectivos
5.
J Occup Rehabil ; 21 Suppl 1: S69-76, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21328063

RESUMO

INTRODUCTION: Asia is the new and favored magnet of economic attention and foreign investments after it made an almost uneventful rebound from the depths of financial crisis of 2008/2009. Not many Western observers fully understand the diversity that is Asia other than perhaps its 2 growing economic giants of China and India. Indeed many smaller countries like Singapore and Malaysia in South East Asia along with Australia and Hong Kong (a Special Administrative Region within China) look to symbiotic relationships with these two economic giants. The purpose of this discussion paper is to examine the current issues related to the development and provision of occupational rehabilitation services in Singapore and Malaysia with a forward-looking view of how Asia's different developing societies could potentially benefit from better alignment of occupational rehabilitation practices and sharing of expertise through international collaboration and dialogue platforms. METHODS: Seven therapists and one physician who are frequently involved in occupational rehabilitation services in their home countries critically reviewed the current issues in Singapore and Malaysia which included analysis of the prevalence and cost of occupational injury; overview of workers' compensation system; current practices, obstacles, and challenges in providing occupational rehabilitation and return to work practices. They also offered opinions about how to improve the occupational rehabilitation programs of their two home countries. CONCLUSION: Even though Malaysia and Singapore are two different countries, in many ways their current provision of occupational rehabilitation services and the problems they face with are very similar. There is a lot of room for systemic improvements that require government support and action. Most prominently, the training of more healthcare professionals in the assessment and rehabilitation of the injured worker should be encouraged. There could be better liaison between the many stakeholders and more funding made available to develop resources and to jump start strategic programs. As these two countries are witnessing rapid economic growth, more resources should be allocated to establish holistic care of the injured workers emphasizing early interventions and prevention of chronic disabilities.


Assuntos
Serviços de Saúde do Trabalhador/organização & administração , Política Pública , Reabilitação Vocacional , Indenização aos Trabalhadores/organização & administração , Humanos , Malásia , Reabilitação Vocacional/tendências , Singapura , Mudança Social , Indenização aos Trabalhadores/tendências
6.
Tech Coloproctol ; 10(3): 245-8, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16969608

RESUMO

Sigmoid volvulus is a rare presentation of Hirschsprung's disease. A 38-year-old male presented with acute intestinal obstruction and a history of chronic constipation since childhood. Abdominal radiographs showed megarectum and megacolon with dissipated feces. Sigmoidoscopy revealed gangrenous bowel mucosa affecting the sigmoid colon. Emergency laparotomy revealed a grossly dilated bowel with concurrent gangrenous sigmoid volvulus. He was treated successfully with proctocolectomy with J-pouch-anal anastomosis and a defunctioning ileostomy. Histological analysis was consistent with short segment Hirschsprung's disease. Although uncommon, adult Hirschsprung's disease is a cause of chronic constipation and can present acutely with a sigmoid volvulus. Mortality in cases with sigmoid volvulus is greater than in cases without (15.4% vs. 0%). A better awareness of this condition will facilitate management.


Assuntos
Doença de Hirschsprung/complicações , Doença de Hirschsprung/diagnóstico , Volvo Intestinal/etiologia , Doenças do Colo Sigmoide/etiologia , Adulto , Doença de Hirschsprung/cirurgia , Humanos , Volvo Intestinal/diagnóstico por imagem , Volvo Intestinal/cirurgia , Masculino , Radiografia , Doenças do Colo Sigmoide/diagnóstico por imagem , Doenças do Colo Sigmoide/cirurgia
8.
J Hosp Infect ; 58(3): 210-5, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15501336

RESUMO

This is a prospective observational study of a cohort of inpatients exposed to a severe acute respiratory syndrome (SARS) outbreak. Strict infection control policies were instituted. The 70 patients exposed to the SARS outbreak were isolated from the rest of the hospital. They were triaged, quarantined and cohorted in three open plan wards. Selective isolation was carried out immediately when symptoms and signs suspicious of SARS manifested clinically. The patients' ages ranged from 21 to 90 years and 56% had surgery before the quarantine. Sixteen patients with unexplained fever during the period of quarantine were isolated, seven of whom were eventually diagnosed with probable SARS. The crude incidence of SARS in our cohort was 10%. The SARS case fatality was 14%. No secondary transmission of the SARS virus within the cohort was observed. Strict infection control, together with appropriate triaging, cohorting and selective isolation, is an effective and practical model of intervention in cohorts exposed to a SARS outbreak. Such a management strategy eases the logistic constraints imposed by demands for large numbers of isolation facilities in the face of a massive outbreak.


Assuntos
Infecção Hospitalar/epidemiologia , Infecção Hospitalar/prevenção & controle , Surtos de Doenças , Controle de Infecções/métodos , Síndrome Respiratória Aguda Grave/epidemiologia , Síndrome Respiratória Aguda Grave/prevenção & controle , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Infecção Hospitalar/etiologia , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Isolamento de Pacientes , Estudos Prospectivos , Síndrome Respiratória Aguda Grave/etiologia , Singapura/epidemiologia
9.
Singapore Med J ; 45(10): 494-6, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15455172

RESUMO

Cystic adrenal lesions are common, but cystic pheochromocytomas are rare. In the setting of a cystic adrenal mass in a patient with multiple endocrine neoplasia syndrome (MEN) IIB, the diagnosis of pheochromocytoma must be considered. We report a 29-year-old woman with typical phenotype of MEN IIB (marfanoid habitus, thick blubbery lips, mucosal ganglioneuromas) and a history of medullary thyroid carcinoma. She presented with headaches, palpitations and tremors. Computed tomography revealed a left cystic adrenal mass. The likelihood of the lesion being a pheochromocytoma was thought to be low due to its cystic appearance. However, urine ephinephrine and metanephrine levels were elevated. She underwent a left adrenalectomy and histological examination revealed a cystic pheochromocytoma.


Assuntos
Neoplasias das Glândulas Suprarrenais/diagnóstico , Neoplasia Endócrina Múltipla Tipo 2b , Feocromocitoma/diagnóstico , Neoplasias das Glândulas Suprarrenais/cirurgia , Adulto , Feminino , Humanos , Feocromocitoma/cirurgia
10.
Biol Reprod ; 62(1): 8-15, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10611061

RESUMO

In chickens, oviposition is correlated with increased plasma levels of the neurohypophysial hormone vasotocin, and vasotocin stimulates contraction of uterine strips in vitro. A gene encoding a vasotocin receptor subtype that we have designated the VT1 receptor was cloned from the domestic chicken. The open reading frame encodes a 370-amino acid polypeptide that displays seven segments of hydrophobic amino acids, typical of guanine nucleotide-protein-coupled receptors. Other structural features of the VT1 receptor include two potential N-linked glycosylation sites in the extracellular N-terminal region, a conserved aspartic acid in transmembrane domain 2 that is found in nearly all guanine nucleotide-protein-coupled receptors, and two potential protein kinase C phosphorylation sites in the third intracellular loop and C-terminal tail. Expressed VT1 receptors in COS7 cells bind neurohypophysial hormones with the following rank order of potency: vasotocin congruent with vasopressin > oxytocin congruent with mesotocin > isotocin. In addition, the expressed VT1 receptor mediates vasotocin-induced phosphatidylinositol turnover and Ca(2+) mobilization. In the chicken, expression of VT1 receptor gene transcripts is limited to the shell gland (uterus) and the brain. Thus, the VT1 receptor that we have cloned may mediate contractions of the shell gland during oviposition and activate reproductive behaviors known to be stimulated by vasotocin in lower vertebrates.


Assuntos
Encéfalo/metabolismo , Galinhas/genética , Clonagem Molecular , Expressão Gênica , Oviposição , Receptores de Vasopressinas/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Células COS , Feminino , Dados de Sequência Molecular , Receptores de Vasopressinas/química , Transfecção , Útero/metabolismo
12.
J Biol Chem ; 265(19): 11265-72, 1990 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-1694176

RESUMO

We discovered an enzyme in human platelets that deamidates substance P and other tachykinins. Because an amidated carboxyl terminus is important for biological activity, we purified and characterized this deamidase. The enzyme, released from human platelets by thrombin, was purified to homogeneity by ammonium sulfate precipitation, followed by chromatography on an octyl-Sepharose column and chromatofocusing on PBE 94. The purified enzyme exhibits esterase, peptidase, and deamidase activities. The peptidase activity (with furylacryloyl-Phe-Phe) is optimal at pH 5.0 while the esterase (benzoyl-tyrosine ethyl ester) and deamidase (D-Ala2-Leu5-enkephalinamide) activities are optimal at pH 7.0. With biologically important peptides, the enzyme acts both as a deamidase (substance P, neurokinin A, and eledoisin) and a carboxy-peptidase (with bradykinin, angiotensin I, substance P-free acid, oxytocin-free acid) at neutrality, although the carboxypeptidase action is faster at pH 5.5. Enkephalins, released upon deamidation of enkephalinamides, were not cleaved. Gly9-NH2 of oxytocin was released without deamidation. Peptides with a penultimate Arg residue were not hydrolyzed. Some properties of the deamidase are similar to those reported for cathepsin A. The deamidase is inhibited by diisopropylfluorophosphate, inhibitors of chymotrypsin-type enzymes, and mercury compounds while other inhibitors of catheptic enzymes, trypsin-like enzymes, and metalloproteases were ineffective. In gel filtration, the native enzyme has an Mr = 94,000 while in non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis the Mr = 52,000 indicating it exists as a dimer. After reduction, deamidase dissociates into two chains of Mr = 33,000 and 21,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. [3H]diisopropylfluorophosphate labeled the active site serine in the Mr = 33,000 chain. The first 25 amino acids of both chains were sequenced. They are identical with the sequences of the two chains of lysosomal "protective protein" which, in turn, has sequence similarity to the KEX1 gene product and carboxypeptidase Y of yeast. This protective protein complexes with beta-galactosidase and neuraminidase in lysosomes and is vitally important in maintaining their activity and stability. A defect in this protein is the cause of galactosialidosis, a severe genetic disorder. The ability of physiological stimuli (e.g. thrombin or collagen) to release the deamidase from platelets indicates that it may also be involved in the local metabolism of bioactive peptides.


Assuntos
Plaquetas/enzimologia , Lisossomos/análise , Peptídeo Hidrolases/sangue , Taquicininas/metabolismo , Sequência de Aminoácidos , Angiotensina I/metabolismo , Cromatografia , Eledoisina/metabolismo , Esterases/antagonistas & inibidores , Esterases/sangue , Humanos , Concentração de Íons de Hidrogênio , Isoflurofato/farmacologia , Cinética , Lisossomos/metabolismo , Dados de Sequência Molecular , Peso Molecular , Neurocinina A/metabolismo , Inibidores de Proteases/farmacologia , Substância P/metabolismo , Especificidade por Substrato
13.
Sci China B ; 33(5): 599-605, 1990 May.
Artigo em Inglês | MEDLINE | ID: mdl-2390165

RESUMO

A peptide trypsin inhibitor was isolated and purified from the roots of Trichosanthes kirilowii (a Chinese medical herb) by using immobilized anhydro-trypsin affinity chromatography and HPLC C18 column reverse chromatography. It contains two major components, both consisting of 27 amino acid residues with three pairs of disulfide bonds. The sequence determination indicated that the difference between them is only in the ninth position, being Gln and Lys, respectively. The peptide bond of the inhibitor reactive site Arg-Ile (3-4) is easy to cleave at low pH by trypsin, resulting in a modified inhibitor. It might be the smallest naturally occurring protein inhibitor so far known. The modification reaction of the Trichosanthes inhibitor with trypsin is similar to the catalytic enzyme-substrate reaction. The dissociation constant of the modified inhibitor with trypsin is around fourfold that of the natural inhibitor.


Assuntos
Inibidores da Tripsina/análise , Sequência de Aminoácidos , Dados de Sequência Molecular , Plantas Medicinais/análise , Inibidores da Tripsina/síntese química
14.
Zhonghua Zhong Liu Za Zhi ; 11(4): 291-3, 1989 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-2625113

RESUMO

Ninety-one patients with parasellar lesions proved by pathology and surgery from July 1982 to May 1987 and 22 patients misdiagnosed clinically or by CT are reported. The authors found that: 1. Besides the main group of parasellar lesions such as pituitary tumor, meningioma, and craniopharyngioma, some rare disease like glioma, pituitary carcinoma, chordoma, olfactory neuroblastoma, Rathke's pouch and tuberculoma of optic nerve were also found which comprised 12% (11/91) in this series. They should be considered in differential diagnosis; 2. Correct diagnosis was made when CT findings conformed well with the clinical features. Over-emphasis of clinical features or neglect of CT findings should be discouraged as they may lead to erroneous diagnosis; 3. In this series, the highest correct diagnosis rates were: pituitary tumor (95%), parasellar meningioma (78%) and craniopharyngioma (50%). It is difficult to make a correct diagnosis for these rare disease entities before operation; and 4. CT scan cannot completely replace angiography and ventriculography when they are needed for differential diagnosis.


Assuntos
Craniofaringioma/diagnóstico por imagem , Neoplasias Meníngeas/diagnóstico por imagem , Meningioma/diagnóstico por imagem , Neoplasias Hipofisárias/diagnóstico por imagem , Adulto , Neoplasias Encefálicas/diagnóstico por imagem , Criança , Erros de Diagnóstico , Glioma/diagnóstico por imagem , Humanos , Sela Túrcica , Tomografia Computadorizada por Raios X
15.
Biochem Biophys Res Commun ; 154(3): 1323-9, 1988 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-3408501

RESUMO

Human plasma carboxypeptidase N was purified to homogeneity and its active and inactive subunits were separated. By introducing a novel technique, both forms of the active subunit (Mr = 55,000 and Mr = 48,000) were isolated. N-terminal sequencing of the active subunit of human carboxypeptidase N revealed significant homology with the N-terminal sequence of bovine carboxypeptidase H (43% identity) and to a lesser extent with carboxypeptidase A (29% identity) or carboxypeptidase B (18% identity). The active subunit of carboxypeptidase N was hydrolyzed with trypsin and 4 of the tryptic peptides were isolated by HPLC and sequenced. The sequences of the four peptides were homologous (39-64% identity) with regions of carboxypeptidase H corresponding to the middle (residues 148-175) and C-terminal portion (residues 321-408). These regions had essentially no homology with carboxypeptidase A or B. These data indicate that carboxypeptidase H and the active subunit of carboxypeptidase N may have diverged from a common ancestral gene.


Assuntos
Carboxipeptidases , Lisina Carboxipeptidase , Sequência de Aminoácidos , Carboxipeptidases/sangue , Carboxipeptidases/isolamento & purificação , Humanos , Lisina Carboxipeptidase/sangue , Lisina Carboxipeptidase/isolamento & purificação , Substâncias Macromoleculares , Dados de Sequência Molecular , Peso Molecular , Fragmentos de Peptídeos/análise , Tripsina
16.
Sci Sin B ; 28(11): 1163-6, 1985 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-3939264

RESUMO

The Lys fragment of mung bean trypsin inhibitor can combine with bovine trypsin to form a complex at an equal molar ratio. The single crystals of the complex were obtained by using the micro-still-setting method and the X-ray diffraction extended to 1.8A resolution. Its space group is P212121 with cell dimensions a = 62.9(1)A, b = 63.4(1)A and c = 69.7 (2)A. There is one complex molecule in a crystallographic asymmetric unit.


Assuntos
Fragmentos de Peptídeos/análise , Inibidores da Tripsina/análise , Animais , Bovinos , Cristalografia , Fabaceae , Lisina , Plantas Medicinais , Tripsina
17.
Biol Chem Hoppe Seyler ; 366(9): 879-85, 1985 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3907662

RESUMO

After reduction and alkylation of the disulfide bonds of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.) followed by CNBr cleavage three peptide fragments with 68, 62 and 11 amino-acid residues could be separated on DEAE-Sepharose CL-6B. The peptides or the inhibitor itself were further specifically cleaved either by trypsin or by the mixture of (CH3)2SO/HCl/HBr at the arginyl- and the tryptophyl-peptide bond, respectively. The complete amino-acid sequences of the peptides were determined by manual solid phase DABITC/PITC double coupling micro-method and the primary structure of the arrowhead inhibitor B consisting of 141 amino-acid residues was then elucidated. Twenty pairs of amino-acid residues are repeated in the molecule of this inhibitor, three of these pairs even occur three times. The possible locations of the reactive sites are discussed. On the basis of sequence comparisons between this inhibitor and all other serine proteinase inhibitors the arrowhead inhibitor may belong to a new family.


Assuntos
Proteínas de Plantas/isolamento & purificação , Plantas/análise , Inibidores de Proteases , Sequência de Aminoácidos , Brometo de Cianogênio , Fragmentos de Peptídeos/análise , Tripsina
18.
Hoppe Seylers Z Physiol Chem ; 365(10): 1211-7, 1984 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-6440850

RESUMO

A double-headed trypsin inhibitor peptide was isolated and purified from the root of Trichosanthes kirilowii Maxim (Cucurbitaceae), a Chinese medical herb, by 2.5% trichloroacetic acid and heat treatment followed by affinity chromatography with immobilized trypsin and ion-exchange chromatography. This inhibitor, consisting of 41 amino-acid residues with three pairs of disulfide bonds was sequenced. Two active domains were found to be located at two disulfide loops composed of eight (Pos. 17-24) and nine (Pos. 29-37) amino-acid residues, respectively. It inhibits two molecules of trypsin simultaneously and might be regarded as the smallest double-headed trypsin inhibitor (Mr = 4575) so far known. The chemical modification of the inhibitor with cyclohexandione and citraconic anhydride showed that Arg20-Gly21 and Lys30-Leu31 corresponded to the two reactive sites, respectively. The discovery of the Trichosanthes inhibitor is of importance not only for the study on the structure-function relationship of proteinase inhibitor peptides but also for the search for low molecular mass inhibitors of clinical value among Chinese medical herbs.


Assuntos
Plantas Medicinais/análise , Inibidores da Tripsina/análise , Sequência de Aminoácidos , Arginina/análise , Sítios de Ligação , Fenômenos Químicos , Química , Cromatografia DEAE-Celulose/métodos , Lisina/análise , Inibidores da Tripsina/isolamento & purificação
19.
Sci Sin B ; 27(9): 918-25, 1984 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-6441252

RESUMO

Two peptide chains A1 and A2 of the Lys active fragment, linked via a couple of inter-disulfide bonds, could be separated from each other after reduction with dithiothreitol and gel filtration on Sephadex G-25. Reoxidation of the reduced peptide chain A1 resulted in recovering the inhibitory activity with 25% yield, based on the original activity of the Lys fragment. The A1 active fragment was further purified by affinity chromatography with immobilized trypsin. Sephadex G-25 gel filtration produced two forms of the A1 active fragment, the major fraction being a monomer and the minor one being a dimer with lower activity. The results obtained offered evidence of the evolution of mung bean inhibitor from an ancestral single-headed inhibitor by fused gene duplication with A2 as a connecting peptide. The CD spectra of the Lys fragment and the reoxidized peptide chain A1 were also compared.


Assuntos
Inibidores da Tripsina/análise , Aminoácidos/análise , Dicroísmo Circular , Dissulfetos/análise , Lisina , Peso Molecular , Oxirredução , Peptídeos/análise , Conformação Proteica , Espectrofotometria Ultravioleta/métodos , Compostos de Sulfidrila/análise
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