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1.
Front Nutr ; 10: 1177897, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37252233

RESUMO

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

2.
3 Biotech ; 13(5): 145, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37124983

RESUMO

Plant growth, promoting, bacteria, (PGPB) can improve plant germination and growth in heavy metal-contaminated land and enhance heavy metal removal efficiency. In this study, we isolated PGPR bacterial strains which can withstand heavy metal pollution and tested their ability to improve barley germination under heavy metal stress. Out of 16 multi-resistant heavy metal isolates, strain MD36 was identified by 16S rRNA sequencing and shared close relation to different species of the genus Glutamicibacter. The new isolated strain showed other important PGPR activities, mainly IAA production and salt tolerance. The effect of adding the strain MD36 to barley grains under heavy metal stress enhanced their germination up to 100%, while the percentage of germination ranged between 0 and 20% for non-inoculated grains. In addition, in these conditions, MD36 can significantly enhance barley growth by reducing the heavy metal effect. This study strongly recommends the use of MD36 as seed coatings trials in the field to enhance growth and yield in soils contaminated with heavy metals, as well as in bioremediation of HM-contaminated salt-containing soils and water.

3.
Curr Microbiol ; 80(3): 95, 2023 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-36737528

RESUMO

Proteolytic enzymes that are currently used to meet industrial demand are usually derived from Bacillus species. They find multiple technical applications, particularly they have been increasingly used as a key bio-additive in detergents. In this study, a novel alkalophilic bacterium was isolated from contaminated soil, exhibiting 1400 U/ml proteolytic activity, and identified as Bacillus swezeyi B2. The crude enzyme likely contained a single extracellular protease. This enzyme revealed optimum activity at pH 10 and 70 °C and was highly alkaline thermostable (7-12.5) and up to 70 °C. The protease activity was completely inhibited by Phenylmethylsulfonyl fluoride (PMSF) suggesting that it belongs to the serine protease group. It was highly stable in the presence of the strong anionic surfactant (SDS) and oxidizing agents (H2O2). The supernatant was lyophilized and showed high storage stability retaining 100% of its original activity after one year of conservation at 4 °C. The lyophilized product was evaluated for its detergent efficacy, it revealed excellent compatibility with various laundry detergents keeping its full original activity after incubation for 1 h with seven solid and liquid commercial detergents and it effectively removed chocolate stains at low washing temperature (40 °C) and low supplementation level (125 U/ml). The features of this single alkaline and thermotolerant protease, stable toward surfactants, oxidizing agents, and commercial detergents with stain removal efficacy support its ideal choice for supplementation in detergent formulations.


Assuntos
Bacillus , Detergentes , Detergentes/farmacologia , Tensoativos/farmacologia , Oxidantes , Peróxido de Hidrogênio/farmacologia , Proteínas de Bactérias/farmacologia , Serina Proteases , Serina Endopeptidases , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Temperatura
4.
J Food Sci Technol ; 53(7): 2902-2912, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27765961

RESUMO

Bioactive Liza aurata protein hydrolysates (LAPHs) were prepared by treatment with Trypsine (PH-TR), Esperase (PH-ES), enzyme preparations from Pseudomonas aeruginosa A2 (PH-A2), Bacillus subtilis A26 (PH-A26) and Liza aurata (PH-LA). Their functional properties and antioxidant activities were evaluated. The hydrolysates had degree of hydrolysis (DH) values ranging from 8.15 % to 13.05 %. Reverse-phase HPLC analyses of the LAPHs showed considerable variation in peptide composition. All hydrolysates had high protein content (83.14 %-86.43 %). Glutamic acid, Glutamine (Glx) and Lysine (Lys) were the most abundant amino acids. All protein hydrolysates had a good solubility emulsifying and foam properties were found to be considerably improved by enzymatic hydrolysis. In addition, all hydrolysates showed varying degrees of antioxidant activities evaluated by various in vitro tests. Further, all LAPHs did not show hemolytic activity towards human erythrocytes. The results thus revealed that protein hydrolysates from golden grey mullet could be used as food additives possessing both antioxidant activity and functional properties.

5.
Food Chem ; 196: 1346-54, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-26593626

RESUMO

This study investigated the fine structure and biochemical characterization of trypsin from the viscera of Liza aurata. The purified enzyme displayed an apparent molecular weight of 23 kDa as determined by sodium dodecyl sulphate-polyaccrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature for the proteolytic activity were 10.0 and 50 °C, respectively. Trypsin was strongly inhibited by serine protease inhibitor. The cDNA of the mature trypsin was cloned and sequenced. It encodes a protein of 222 amino acids, having only 86% of identity with its most homologous trypsin II of the Salmo salar. A phylogenic analysis showed that L. aurata trypsin (LAT) is close to fish enzymes. Given the high amino acid sequence homology between fish enzymes, a 3-D structure model was built using the structure of S. salar as a template. According to this model, structural features common with warm-active trypsins would explain why LAT acts at high temperatures, unlike cold adapted enzymes.


Assuntos
Eletroforese em Gel de Poliacrilamida/métodos , Peixes/metabolismo , Imageamento Tridimensional/métodos , Tripsina/química , Animais , Peso Molecular , Temperatura
7.
Biomed Res Int ; 2014: 345980, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24804214

RESUMO

The present study describes the isolation of a new protease producing Streptomyces strain HS1 and the biochemical characterization of the secreted proteases. By sequencing of its noted 16S rDNA, HS1 strain was found to have a 100% identity with Streptomyces flavogriseus. The highest protease production was found using FermII media. In these conditions maximum protease production (99 U/mL) was obtained after 96 h incubation at 30°C and 150 rpm. HS1 strain produced at least five proteases as revealed by zymogram technique. The enzyme preparation exhibited activity over a broad range of pH (5-11) and temperature (25-70°C). Optimum activity was observed at a pH of 7.0 and a temperature of 50°C. Proteolytic activity was significantly unaffected by Ca(2+) and Mg(2+). EDTA and PMSF highly decreased the original activity. The crude extracellular proteases showed high stability when used as a detergent additive. These properties offer an interesting potential for enzymatic hydrolysis at the industrial level.


Assuntos
Proteínas de Bactérias , Detergentes/química , Peptídeo Hidrolases , Streptomyces/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , Estabilidade Enzimática , Temperatura Alta , Concentração de Íons de Hidrogênio , Peptídeo Hidrolases/química , Peptídeo Hidrolases/isolamento & purificação
9.
Afr J Paediatr Surg ; 10(2): 160-3, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23860068

RESUMO

BACKGROUND: The purpose of the study is to present the author's experience with congenital bladder diverticula in seven pediatric patients at a developing world tertiary care center. MATERIALS AND METHODS: Records of seven patients diagnosed and treated as congenital bladder diverticulum, from January 1998 to December 2009 were retrospectively reviewed for age, sex, clinical symptoms, investigative work-up, operative notes, and postoperative follow-up. RESULTS: All patients were males. Age at presentation ranged from six months to six years (mean three years and six months). All were manifested postnatally by urinary tract infection in four cases, bladder retention in three cases and abdominal pain in two cases. Diagnosis was suggested by ultrasound and confirmed by voiding cystourethrography (VCUG) in all cases and urethrocystoscopy in three cases. Open surgical excision of diverticulum was done in all the patients associated with ureteral reimplantation in four patients with VCUG-documented high-grade vesicoureteral reflux (VUR). Average follow-up was four years; there is a resolution of symptoms and no diverticulum recurrence at the defined mean follow-up. CONCLUSION: Recurrent urinary tract infections and voiding dysfunction in pediatric population should always be evaluated for congenital bladder diverticulum. Investigations such as abdominal ultrasound, VCUG and nuclear renal scanning, form an important part of preoperative diagnostic work-up and postoperative follow up. Diverticulectomy with ureteral reimplantation in case of high-grade reflux, provides good results without recurrence.


Assuntos
Cistoscopia/métodos , Divertículo/diagnóstico , Bexiga Urinária/anormalidades , Procedimentos Cirúrgicos Urológicos/métodos , Criança , Pré-Escolar , Diagnóstico Diferencial , Divertículo/congênito , Divertículo/cirurgia , Seguimentos , Humanos , Lactente , Masculino , Estudos Retrospectivos , Bexiga Urinária/cirurgia , Urografia
10.
Afr J Paediatr Surg ; 9(3): 217-22, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23250243

RESUMO

OBJECTIVE: Our purpose was to review our experience with congenital diaphragmatic hernia emphasizing diagnosis, management, and outcome. STUDY DESIGN: We conducted a retrospective review of all cases of babies with congenital diaphragmatic hernia diagnosed and treated in our centre from 1998 to 2010. RESULTS: There were 28 congenital diaphragmatic hernia cases, 13 girls and 15 boys with a mean weight birth of 3 kg. Three patients (10, 6% of cases) died within a few hours after admission. In the remaining cases, surgery was performed after a stabilization period of 2 days. The diaphragmatic defect was sitting in the posterolateral left in 23 cases and right in 2 cases. Its dimensions were on average 4,5 cm, tow cases of agenesis of the cupola were seen and required the placement of gortex prosthesis. The remaining cases are treated by direct closure of defect. Postoperative course was marked by an early death in context of respiratory distress in six cases and later with sepsis in tow cases. The outcome was favourable in 17 cases (60, 7%), despite the occurrence of sepsis in four cases and evisceration in two cases. CONCLUSIONS: Congenital diaphragmatic hernia remains a serious disease with high mortality and morbidity despite advances in prenatal diagnosis and neonatal resuscitation.


Assuntos
Hérnias Diafragmáticas Congênitas , Herniorrafia/métodos , Diagnóstico Pré-Natal/métodos , Feminino , Seguimentos , Hérnia Diafragmática/diagnóstico , Hérnia Diafragmática/cirurgia , Humanos , Incidência , Recém-Nascido , Masculino , Complicações Pós-Operatórias/epidemiologia , Prognóstico , Estudos Retrospectivos , Fatores de Tempo , Tunísia/epidemiologia
12.
Fish Physiol Biochem ; 37(1): 123-33, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20711672

RESUMO

Three trypsin isoforms A, B and C were purified to homogeneity from the viscera of sardinelle (Sardinella aurita). Purification was achieved by ammonium sulfate precipitation (20-70% (w/v)), Sephadex G-100 gel filtration and Mono Q-Sepharose anion-exchange chromatography. The molecular weights of these purified enzymes were estimated to be 28.8 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Based on the native PAGE and casein-zymography, each purified trypsin appeared as a single band. Trypsins A and C exhibited the maximal activity at 55°C, while trypsin B at 50°C. All isoforms showed the same optimal pH (pH 9.0) using Nα-benzoyl-DL: -arginine-p-nitroanilide (BAPNA) as a substrate. The three trypsins were stable at temperatures below 40°C and over a broad pH range (7.0-11.0). The activities of the three isoforms were strongly inhibited by soybean trypsin inhibitor and phenylmethylsulfonyl fluoride, a serine protease inhibitor, and partially inhibited by ethylenediaminetetraacetic acid, a metalloenzyme inhibitor. Kinetic constants of trypsins A, B and C for BAPNA were evaluated at 25°C and pH 9.0. The values of K (m) and k (cat) were 0.125, 0.083 and 0.10 mM, and 2.24, 1.21 and 5.76 s(-1), respectively. The N-terminal sequences of the first 10 amino acids were "I V G G Y E C Q K Y" for trypsin A and "I V G G Y E A Q S Y" for trypsins B and C. These sequences showed highly homology to other fish trypsins.


Assuntos
Peixes/fisiologia , Tripsina/isolamento & purificação , Tripsina/metabolismo , Vísceras/enzimologia , Sequência de Aminoácidos , Animais , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Isoenzimas/química , Isoenzimas/isolamento & purificação , Isoenzimas/metabolismo , Cinética , Metais/farmacologia , Dados de Sequência Molecular , Alinhamento de Sequência , Cloreto de Sódio/farmacologia , Temperatura , Tripsina/química
13.
J Amino Acids ; 2011: 913616, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22312476

RESUMO

The aim of this work was to study some biochemical characteristics of crude alkaline protease extracts from the viscera of goby (Zosterisessor ophiocephalus), thornback ray (Raja clavata), and scorpionfish (Scorpaena scrofa), and to investigate their applications in the deproteinization of shrimp wastes. At least four caseinolytic proteases bands were observed in zymogram of each enzyme preparation. The optimum pH for enzymatic extracts activities of Z. ophiocephalus, R. clavata, and S. scrofa were 8.0-9.0, 8.0, and 10.0, respectively. Interestingly, all the enzyme preparations were highly stable over a wide range of pH from 6.0 to 11.0. The optimum temperatures for enzyme activity were 50°C for Z. ophiocephalus and R. clavata and 55°C for S. scrofa crude alkaline proteases. Proteolytic enzymes showed high stability towards non-ionic surfactants (5% Tween 20, Tween 80, and Triton X-100). In addition, crude proteases of S. scrofa, R. clavata, and Z. ophiocephalus were found to be highly stable towards oxidizing agents, retaining 100%, 70%, and 66%, respectively, of their initial activity after incubation for 1 h in the presence of 1% sodium perborate. They were, however, highly affected by the anionic surfactant SDS. The crude alkaline proteases were tested for the deproteinization of shrimp waste in the preparation of chitin. All proteases were found to be effective in the deproteinization of shrimp waste. The protein removals after 3 h of hydrolysis at 45°C with an enzyme/substrate ratio (E/S) of 10 were about 76%, 76%, and 80%, for Z. ophiocephalus, R. clavata, and S. scrofa crude proteases, respectively. These results suggest that enzymatic deproteinization of shrimp wastes by fish endogenous alkaline proteases could be applicable to the chitin production process.

14.
BMC Genomics ; 10: 311, 2009 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-19602286

RESUMO

BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-I) is a human retrovirus that is etiologically linked to adult T-cell leukemia (ATL), an aggressive and fatal lymphoproliferative disease. The viral transactivator, Tax, is thought to play an important role during the initial stages of CD4+ T-cell immortalization by HTLV-1. Tax has been shown to activate transcription through CREB/ATF and NF-KB, and to alter numerous signaling pathways. These pleiotropic effects of Tax modify the expression of a wide array of cellular genes. Another viral protein encoded by HTLV-I, p30, has been shown to affect virus replication at the transcriptional and posttranscriptional levels. Little is currently known regarding the effect of p30 on the expression and nuclear export of cellular host mRNA transcripts. Identification of these RNA may reveal new targets and increase our understanding of HTLV-I pathogenesis. In this study, using primary peripheral blood mononuclear cells, we report a genome wide analysis of human genes transcriptionally and post-transcriptionally regulated by the HTLV-I protein p30. RESULTS: Using microarray analysis, we analyzed total and cytoplasmic cellular mRNA transcript levels isolated from PBMCs to assess the effect of p30 on cellular RNA transcript expression and their nuclear export. We report p30-dependent transcription resulting in the 2.5 fold up-regulation of 15 genes and the down-regulation of 65 human genes. We further tested nuclear export of cellular mRNA and found that p30 expression also resulted in a 2.5 fold post-transcriptional down-regulation of 90 genes and the up-regulation of 33 genes. CONCLUSION: Overall, our study describes that expression of the HTLV-I protein p30 both positively and negatively alters the expression of cellular transcripts. Our study identifies for the first time the cellular genes for which nuclear export is affected by p30. These results suggest that p30 may possess a more global function with respect to mRNA transcription and the nuclear shuttling of cellular mRNA transcripts. In addition, these alterations in gene expression may play a role in cell transformation and the onset of leukemia.


Assuntos
Estudo de Associação Genômica Ampla , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Processamento Pós-Transcricional do RNA , Transcrição Gênica , Proteínas do Core Viral/metabolismo , Transporte Ativo do Núcleo Celular , Linhagem Celular , Regulação para Baixo , Regulação da Expressão Gênica , Humanos , Leucemia-Linfoma de Células T do Adulto/genética , Leucócitos Mononucleares/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/metabolismo , Regulação para Cima
15.
Tunis Med ; 86(5): 468-72, 2008 May.
Artigo em Francês | MEDLINE | ID: mdl-19469302

RESUMO

BACKGROUND: Adnexal torsion is the most frequent gynaecological emergency in children. It requires an early diagnosis and an urgent surgical treatment. PURPOSE: to study the clinical, paraclinical and therapeutic aspect of adnexal torsion in paediatric population. METHODS: This is a retrospective review of nine girls with the diagnosis of ovarian torsion observed over a 7 years period (January 1999 to December 2005). RESULTS: The average age is 9 years (extreme 6 to 13 years). This pathology was located in 5 cases on the right side and in 3 cases on the left side; a case of bilateral torsion of poly-cystic ovary was encountered in a girl with down syndrome. Clinical presentation is made in all the cases by abdominal pains and vomiting. The disorders of the transit and the urinary signs are associated in 3 and 2 cases respectively, the clinical examination objectified a pelvic defense in all the cases and an abdominal mass in 2 cases. Pelvic ultra-sonography was made in 6 observations and give the diagnosis of torsion of the ovary in 4 cases, whereas it was doubtful in the 2 remaining cases when an ovarian mass was observed. In the 3 remaining cases, this examination was not performed since one the diagnosis of acute appendicitis was retained and the patient operated in emergency. All the children of our series were operated; in 1/3 of the cases we found a necrosis of the ovary. 4 cases out of 9 present a torsion on pathologic ovary (cyst, dysplasia), whereas in the 5 remaining cases, we noted a torsion on healthy ovary. 4 young girls have undergoes a annexectomy, of which one was bilateral. The evolution was favorable in all the cases. CONCLUSION: Adnexal torsion is a surgical emergency that need an early diagnosis and management to preserve ovarian function in girls and Doppler sonography every must be done every time there is a pelvic pain without fever in girls


Assuntos
Doenças dos Anexos , Anormalidade Torcional , Doenças dos Anexos/diagnóstico , Doenças dos Anexos/cirurgia , Adolescente , Criança , Feminino , Humanos , Estudos Retrospectivos , Anormalidade Torcional/diagnóstico , Anormalidade Torcional/cirurgia
16.
J Biol Chem ; 282(19): 14608-15, 2007 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-17360706

RESUMO

Human T-cell lymphotrophic virus type I Rex and p30 are both RNA binding regulatory proteins. Rex is a protein that interacts with a responsive element and stimulates nuclear export of incompletely spliced viral RNAs thereby increasing production of virus particles. In contrast, p30 is involved in the nuclear retention of the tax/rex mRNA leading to inhibition of virus expression and possible establishment of viral latency. How these two proteins, with apparent opposite functions, integrate in the viral replication cycle is unknown. Here, we demonstrate that Rex and p30 form ribonucleoprotein ternary complexes onto specific viral mRNA. Our results explain the selective nuclear retention of tax/rex but not other viral mRNAs by p30. Whereas p30 suppresses Rex expression, it did not affect Rex-mediated nuclear export of RNA containing the Rex response element. In contrast, Rex was able to counteract p30-mediated suppression of viral expression and restore cytoplasmic tax/rex mRNA and Tax protein expression. Together, our data demonstrate a complex regulatory mechanism of antagonizing post-transcriptional regulators evolved by human T-cell lymphotrophic virus type I to allow a vigilant control of viral gene expression.


Assuntos
Regulação Viral da Expressão Gênica , Produtos do Gene rex/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/genética , RNA Viral/metabolismo , Proteínas dos Retroviridae/metabolismo , Latência Viral , Replicação Viral , Animais , Células COS , Linhagem Celular , Chlorocebus aethiops , Produtos do Gene rex/genética , Genes Reporter , Humanos , Imunoprecipitação , Plasmídeos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Viral/genética , Proteínas dos Retroviridae/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
17.
J Biol Chem ; 281(48): 37150-8, 2006 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-17008317

RESUMO

Human T-cell leukemia virus type I is the etiological agent of adult T-cell leukemia/lymphoma, an aggressive and fatal lymphoproliferative malignancy. The virus has evolved strategies to escape immune clearance by remaining latent in most infected cells in vivo. We demonstrated previously that virally encoded p30 protein is a potent post-transcriptional inhibitor of virus replication (Nicot, C., Dundr, M., Johnson, J. M., Fullen, J. R., Alonzo, N., Fukumoto, R., Princler, G. L., Derse, D., Misteli, T., and Franchini, G. (2004) Nat. Med. 10, 197-201). p30 is unable to shuttle out of the nucleus in heterokaryon assays, suggesting the existence of specific retention signals. Because suppression of virus replication relies on nuclear retention of the tax/rex mRNA by p30, determining the retention features of p30 will offer hints to break latency in infected cells and insights into new therapeutic approaches. In this study, we used live cell imaging technologies to study the kinetics of p30 and to delineate its retention signals and their function in virus replication. Notably, this is the first study to identify p30 nucleolar retention domains. Using mutants of p30 that localized in different cellular compartments, we show that post-transcriptional control of virus replication by p30 occurs in the nucleoplasm. We further demonstrate that p30 nuclear/nucleolar retention is dependent upon de novo RNA transcripts and interactions with components of the ribosomal machinery.


Assuntos
Nucléolo Celular/virologia , Núcleo Celular/virologia , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , RNA/química , Ribossomos/química , Proteínas não Estruturais Virais/fisiologia , Sequência de Aminoácidos , Animais , Células COS , Chlorocebus aethiops , Cinética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Plasmídeos/metabolismo , Ligação Proteica , Ribossomos/metabolismo , Proteínas não Estruturais Virais/metabolismo , Replicação Viral
18.
J Bacteriol ; 188(17): 6269-76, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16923894

RESUMO

The ppk gene of Streptomyces lividans encodes an enzyme catalyzing, in vitro, the reversible polymerization of the gamma phosphate of ATP into polyphosphate and was previously shown to play a negative role in the control of antibiotic biosynthesis (H. Chouayekh and M. J. Virolle, Mol. Microbiol. 43:919-930, 2002). In the present work, some regulatory features of the expression of ppk were established and the polyphosphate content of S. lividans TK24 and the ppk mutant was determined. In Pi sufficiency, the expression of ppk was shown to be low but detectable. DNA gel shift experiments suggested that ppk expression might be controlled by a repressor using ATP as a corepressor. Under these conditions, short acid-soluble polyphosphates accumulated upon entry into the stationary phase in the wild-type strain but not in the ppk mutant strain. The expression of ppk under Pi-limiting conditions was shown to be much higher than that under Pi-sufficient conditions and was under positive control of the two-component system PhoR/PhoP. Under these conditions, the polyphosphate content of the cell was low and polyphosphates were reproducibly found to be longer and more abundant in the ppk mutant strain than in the wild-type strain, suggesting that Ppk might act as a nucleoside diphosphate kinase. In light of our results, a novel view of the role of this enzyme in the regulation of antibiotic biosynthesis in S. lividans TK24 is proposed.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Streptomyces lividans/enzimologia , Streptomyces lividans/genética , Trifosfato de Adenosina/metabolismo , Sequência de Bases , Códon de Iniciação , Meios de Cultura , Dados de Sequência Molecular , Fosfatos , Polifosfatos/análise , Polifosfatos/metabolismo , Regiões Promotoras Genéticas/genética , Streptomyces lividans/crescimento & desenvolvimento
19.
J Bacteriol ; 188(2): 677-86, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16385057

RESUMO

The PhoR/PhoP two-component system of Streptomyces lividans was previously shown to allow the growth of the bacteria at low Pi concentrations and to negatively control antibiotic production. The present study focuses on the transcriptional analysis of phoR and phoP, along with the phoU and mtpA genes that are transcribed divergently from the phoRP operon in S. lividans. The effect of phoR, phoP, phoU, and ppk mutations on transcription of these genes was examined under phosphate-replete and phosphate-limited conditions. We demonstrated that phoR and phoP were cotranscribed as a leaderless bicistronic transcript cleaved at discrete sites toward the 3' end of phoR. In addition, phoP could also be transcribed alone from a promoter located at the 3' end of phoR. The phoU and mtpA genes, predicted to encode metal binding proteins, were shown to be transcribed as monocistronic transcripts. The expression of phoR-phoP, phoP, and phoU was found to be induced under conditions of Pi limitation in S. lividans TK24. This induction, requiring both PhoR and PhoP, was significantly weaker in the phoU mutant but much stronger in the ppk mutant than in the parental strain. The expression of mtpA was also shown to be up-regulated when Pi was limiting but independently of PhoR/PhoP. The induction of mtpA expression was much stronger in the phoU mutant strain than in the other strains. This study revealed interesting regulatory interactions between the different genes and allowed us to propose putative roles for PhoU and MtpA in the adaptation to phosphate scarcity.


Assuntos
Regulação Bacteriana da Expressão Gênica , Genes Bacterianos/genética , Óperon/genética , Streptomyces lividans/genética , Sequência de Bases , Meios de Cultura , DNA Intergênico/genética , Dados de Sequência Molecular , Fosfatos , Streptomyces lividans/crescimento & desenvolvimento , Transcrição Gênica
20.
Prog Brain Res ; 150: 495-511, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16186044

RESUMO

The locked-in syndrome (pseudocoma) describes patients who are awake and conscious but selectively deefferented, i.e., have no means of producing speech, limb or facial movements. Acute ventral pontine lesions are its most common cause. People with such brainstem lesions often remain comatose for some days or weeks, needing artificial respiration and then gradually wake up, but remaining paralyzed and voiceless, superficially resembling patients in a vegetative state or akinetic mutism. In acute locked-in syndrome (LIS), eye-coded communication and evaluation of cognitive and emotional functioning is very limited because vigilance is fluctuating and eye movements may be inconsistent, very small, and easily exhausted. It has been shown that more than half of the time it is the family and not the physician who first realized that the patient was aware. Distressingly, recent studies reported that the diagnosis of LIS on average takes over 2.5 months. In some cases it took 4-6 years before aware and sensitive patients, locked in an immobile body, were recognized as being conscious. Once a LIS patient becomes medically stable, and given appropriate medical care, life expectancy increases to several decades. Even if the chances of good motor recovery are very limited, existing eye-controlled, computer-based communication technology currently allow the patient to control his environment, use a word processor coupled to a speech synthesizer, and access the worldwide net. Healthy individuals and medical professionals sometimes assume that the quality of life of an LIS patient is so poor that it is not worth living. On the contrary, chronic LIS patients typically self-report meaningful quality of life and their demand for euthanasia is surprisingly infrequent. Biased clinicians might provide less aggressive medical treatment and influence the family in inappropriate ways. It is important to stress that only the medically stabilized, informed LIS patient is competent to consent to or refuse life-sustaining treatment. Patients suffering from LIS should not be denied the right to die - and to die with dignity - but also, and more importantly, they should not be denied the right to live - and to live with dignity and the best possible revalidation, and pain and symptom management. In our opinion, there is an urgent need for a renewed ethical and medicolegal framework for our care of locked-in patients.


Assuntos
Estado de Consciência , Quadriplegia/fisiopatologia , Quadriplegia/psicologia , Fala , Humanos , Quadriplegia/diagnóstico , Qualidade de Vida
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