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1.
Tunis Med ; 97(6): 802-807, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31872412

RESUMO

BACKGROUND: the shock index (SI) defined by the ratio of systolic blood pressure to heart rate was demonstrated as a simple tool in the triage and orientation of severe trauma patients to trauma centers. AIM: To assess the prognostic value of the SI ≥ 1 in terms of mortality in severe trauma patients admitted to the emergency room. METHODS: We performed a prospective, observational and descriptive study with the inclusion of severe trauma patients over the age of 18 years admitted to the Vital Emergency Room over a 21-month period. SI was calculated at admission: SI = heart rate / systolic blood pressure, a SI threshold value ≥1 was fixed to define two groups: SI<1 and SI≥1. RESULTS: A total of 290 trauma patients were included, 231 (79%) had a SI<1, whereas 59 (21%) had an SI≥1. Mean age was 43.5 ± 18 years, 82% were male. There was a significant difference in hospital mortality at 7 days and at 30 days between the two groups respectively (group SI<1 vs group SI≥1): [12% vs 40%; p <0.001 and 15% vs 47%; p <0.001]. In multivariate analysis, SI≥1 appears as an independent factor of hospital mortality at 7 days [OR = 2.03; 95% CI = 1.3-3.3; p =0.001] and at 30 days [OR = 2.69; 95% CI = 1.4- 5; p =0.002]. CONCLUSION: In severe trauma patients admitted to the emergency department; a SI ≥1 represents a predictive factor of hospital mortality at 7 days and one month.


Assuntos
Serviço Hospitalar de Emergência , Choque/diagnóstico , Triagem/métodos , Ferimentos e Lesões/diagnóstico , Adulto , Pressão Sanguínea/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Mortalidade Hospitalar , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Tempo , Índices de Gravidade do Trauma , Ferimentos e Lesões/mortalidade , Ferimentos e Lesões/fisiopatologia
2.
Tunis Med ; 97(5): 698-703, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31729743

RESUMO

INTRODUCTION: The severity of cardiotropic agents overuse is related to the risk of cardiac and hemodynamic life-threatening situations. Toxicity is attributed to their narrow therapeutic spectrum and pharmacodynamic properties. The clinical presentation, however, remains polymorphic and represents a challenge for the emergency physician to relate accountability to the exact agent. AIM: To evaluate epidemiological, clinical and prognostic profile of patients visiting emergency department in whom iatrogeny secondary to cardiotropic use was diagnosed. METHODS: This was a single-center prospective study over 12 months. We included successively all patients aged over 18 years in whom diagnosis of cardiotropic iatrogeny was made. Cardiotropic related drug-induced events were selected after collegial decision making processing. Prognosis was evaluated in terms of severity and mortality at day 30. Univariate analysis was conducted. P<0.05 was significant. RESULTS: We enrolled 51 patients. Median age was 72 years with IQR (25,75) of (62,78). Sex ratio was 0.64. Twenty cases of misuse were identified (39%) with 51% of cases being related to the physician. Accountability of the adverse drug event (ADE) was 51%. The ADE was considered severe in 45% of cases and the death rate on day 30 was 12%. Drug classes were dominated by beta-blockers in 20 patients (39%) and anti-arrhythmic agents (Amiodarone ®) in 18 patients (35%). Beta-blockers were significantly the most incriminated in the occurrence of severe ADE. A double iatrogeny was found in 13 patients (25%). Misuse and physician-related ADE were found to be predictive of the severity of ADE in univariate analysis with respectively: For misuse:(OR brut=22, CI95%=[5.2;93.5] ; p<0.001) and for related physician ADE (OR brut = 3,7 ; CI95%=[1.1;12] ; P= 0.015). Predictive factors of mortality at day 30 in the univariate analysis were: Past renal failure : OR brut 5,8; CI95%[1,3-26,5]; p=0,015 ; misuse with OR brut=16.7, 95% CI=[1.9-143.5], p=0.002 and severe ADE with OR brut=15, 95% CI=[1.75-129], p=0.032. CONCLUSION: This study showed that ADE related to Cardiotropic agents are frequent and remain a serious condition especially in elderly. Betablockers agents were the mostly incriminated therapeutic class in the severity of the clinical condition by its hemodynamic repercussions responsible of a high rate of hospitalizations and mortality. Misuse and physician-related ADE were found to be predictive of the severity. Whereas, occurrence of severe ADE, misuse and past renal failure were predictive of mortality. Moreover, in 51% patients, ADE was preventable and related to the prescription of physician showing the main role of the preventability and the role of the prescriber in the genesis of this severe condition.


Assuntos
Fármacos Cardiovasculares/efeitos adversos , Adulto , Idoso , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/epidemiologia , Serviço Hospitalar de Emergência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos
3.
Pan Afr Med J ; 33: 251, 2019.
Artigo em Francês | MEDLINE | ID: mdl-31692700

RESUMO

INTRODUCTION: Acute Heart Failure (AHF) is a specific syndromic disorder grouping several heterogeneous clinical conditions frequently seen in the emergency department. This study aimed to describe the epidemiological, clinical, therapeutic and prognostic features of patients with AHF admitted to the emergency department. METHODS: We conducted a prospective, descriptive study in the emergency department. It included all patients admitted with AHF. We studied the epidemiological, clinical, therapeutic and prognostic features of these patients. RESULTS: The study enrolled 180 patients with AHF admitted to the emergency department. Sex ratio was 1.27. The average age of patients was 66±12 years. Eighty-two percent of patients were hypertensive and 69% were known diabetic patients. The causes of decompensation included primarily hypertensive crisis (61.7% of patients), acute coronary syndrome (24% of patients). Respiratory support was mainly provided by CPAP (Continuous Positive Airway Pressure) in 73.3% of cases. Pharmacological treatment was based on nitrate derivatives (70% of cases) and diuretic (40.5% of cases). Acute heart failure incidence at one month was 21.7% (n=39 patients) and mortality rate at 3 months was 13.3%. CONCLUSION: Patients with AHF treated in the emergency department mainly had hypertensive crisis. Treatment is primarily based on CPAP, vasodilators and diuretics. Recurrence rate and mortality rate were high.


Assuntos
Síndrome Coronariana Aguda/complicações , Pressão Positiva Contínua nas Vias Aéreas/métodos , Insuficiência Cardíaca/epidemiologia , Hipertensão/complicações , Síndrome Coronariana Aguda/epidemiologia , Doença Aguda , Adulto , Idoso , Idoso de 80 Anos ou mais , Diuréticos/administração & dosagem , Serviço Hospitalar de Emergência , Feminino , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/terapia , Humanos , Hipertensão/epidemiologia , Masculino , Pessoa de Meia-Idade , Nitratos/administração & dosagem , Prognóstico , Estudos Prospectivos , Recidiva , Tunísia , Adulto Jovem
4.
Pan Afr Med J ; 33: 322, 2019.
Artigo em Francês | MEDLINE | ID: mdl-31692874

RESUMO

INTRODUCTION: Diabetic ketoacidosis (DKA) is a severe metabolic complication of diabetes. Recent years have seen a marked increase in prevalence of diabetic ketoacidosis, but mortality is low. This study aimed to describe the epidemiological, clinical, therapeutic and prognostic features of patients with severe or moderate DKA admitted to the Emergency Department. METHODS: He conducted a prospective, descriptive study including patients with moderate or severe DKA. Standardized care protocol. We studied the epidemiological, clinical, therapeutic and prognostic features of these patients. RESULTS: The study involved 185 patients with moderate or severe DKA. The average age of patients was 38+/-18 years, with a sex ratio of 0.94. Known diabetes was reported in 159 patients (85%) of whom 116 had type 1 diabetes. The most common factors of decompensation were treatment discontinuation in 42% and infection in 32%. Average blood glucose was 32.7+/-12 mmol/L, pH =7.14+/-0.13, HCO3- =7.2+/-3.56 mmol/L. The mean duration of intravenous insulin was 17.3 +/- 16 hours. Hypoglycaemia was reported in 26 patients (14%), hypokalemia in 80 (43%) patients and hyperchloraemic mineral acidosis in 43 patients (23%). Intrahospital mortality was 2.1%. CONCLUSION: Diabetic ketoacidosis occurs in young subjects treated with insulin therapy. Treatment is based on intravenous insulin associated with correction of fluid deficit. Complications mainly include hypokalemia and hypoglycemia and mortality is low.


Assuntos
Diabetes Mellitus Tipo 1/epidemiologia , Diabetes Mellitus Tipo 2/epidemiologia , Cetoacidose Diabética/epidemiologia , Insulina/administração & dosagem , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Glicemia/metabolismo , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 2/complicações , Cetoacidose Diabética/tratamento farmacológico , Serviço Hospitalar de Emergência , Feminino , Humanos , Hipoglicemia/epidemiologia , Hipoglicemia/etiologia , Hipoglicemiantes/administração & dosagem , Hipopotassemia/epidemiologia , Hipopotassemia/etiologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
5.
Artigo em Francês | AIM (África) | ID: biblio-1268563

RESUMO

Introduction: l'acidocétose diabétique (ACD) est une complication métabolique grave du diabète. Son incidence est en augmentation ces dernières années, cependant sa mortalité reste faible. L'objectif de cette étude a été de décrire les caractéristiques épidémiologiques, cliniques, thérapeutiques et pronostiques des patients admis aux urgences pour ACD sévère ou modérée. Méthodes: il s'agissait d'une étude prospective, descriptive qui a inclus les ACD modérée ou sévère. Standardisation du protocole de prise en charge thérapeutique. Nous avons étudié les caractéristiques épidémiologiques, cliniques, thérapeutiques et pronostiques chez ces patients. Résultats: nous avons inclus 185 patients avec ACD sévère ou modérée. L'âge moyen a été de 38±18 ans; le sexe ratio=0,94. Diabète connue= 159 patients (85%) dont 116 étaient des diabétiques type 1. Les facteurs de décompensation les plus fréquents étaient l'arrêt du traitement chez 42% et l'infection chez 32%. La glycémie moyenne a été de 32,7±12mmol/L, pH =7,14±0,13, HCO-3 =7,2±3,56 mmol /L. La durée moyenne de l'insuline intraveineuse était de 17,3±16 heures. L'hypoglycémie a été observée chez 26 patients (14%), l'hypokaliémie chez 80 (43%). La mortalité au cours de l'hospitalisation a été de 2,1%. Conclusion: l'acidocétose diabétique survient chez les sujets jeunes traités par insulinothérapie. Le traitement est à base d'insuline par voie intraveineuse en plus de la correction du déficit hydrique. Les complications sont essentiellement l'hypokaliémie et l'hypoglycémie; et la mortalité reste faible


Assuntos
Cetoacidose Diabética/diagnóstico , Cetoacidose Diabética/epidemiologia , Cetoacidose Diabética/terapia , Serviço Hospitalar de Emergência , Tunísia
6.
J Stroke Cerebrovasc Dis ; 26(5): 1007-1012, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28129995

RESUMO

BACKGROUND: Several studies showed a correlation between C-reactive protein and mortality in spontaneous intracerebral hemorrhage. However, the best time to measure C-reactive protein to assess prognosis is not yet clear. The purpose of this study was to determine if initial or H24-C-reactive protein is independently associated with 30-day mortality in intracerebral hemorrhage. METHODS: This is a retrospective study done within years 2010-2015. All intracerebral hemorrhage cases with missing data or with autoimmune disease or neoplasm were excluded. Univariate and multivariate analyses were assessed for initial C-reactive protein, H24-C-reactive protein, and confounding factors. RESULTS: Of 122 patients, 91 were selected. Only H24-C-reactive protein, hematoma volume, and infratentorial origin were independently associated with 30-day mortality in intracerebral hemorrhage. When adjusted with intracerebral hemorrhage score, H24-C-reactive protein with a cutoff value of 30 mg/L independently predicted 30-day mortality. CONCLUSIONS: This study suggests that H24-C-reactive protein may be a more reliable marker than initial C-reactive protein in the prediction of mortality in intracerebral hemorrhage. A large multicentric study is necessary to confirm the interest of including H24-C-reactive protein to a modified intracerebral hemorrhage score for the prediction of 30-day mortality.


Assuntos
Proteína C-Reativa/metabolismo , Hemorragia Cerebral/sangue , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Hemorragia Cerebral/diagnóstico , Hemorragia Cerebral/mortalidade , Feminino , Mortalidade Hospitalar , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Valor Preditivo dos Testes , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo
7.
Biosci. j. (Online) ; 32(1): 226-237, jan./fev. 2016.
Artigo em Inglês | LILACS | ID: biblio-965284

RESUMO

The secondary metabolite composition, antioxidant activities, and microbial inhibition properties of leaves of two Cistus species; C. monspeliensis and C. salvifolius were investigated using three solvent extracts (ethanol, hexane and distilled water). Ethanol extracts were most efficient at extracting phenolics, flavonoids and condensed tannins compared to hexane and distilled water for both Cistus species. A total antioxidant test (TAA) and two radical scavenging tests (DPPH and ABTS) indicated that the 70% ethanolic extract from C. salvifolius leaves had stronger antioxidant activity compared to the C. monspeliensis 70% ethanol extract, while the aqueous extract of C. monspeliensis was much stronger than the aqueous extract or the 70% ethanol extract of C. salvifolius. Overall, the polar extracts were more active in both species than the non-polar extracts. Thus aqueous ethanol extracts of the leaves of each Cistus species were tested for their ability to inhibit seven pathogenic microbial strains, including Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, and Candida albicans. Leaf ethanol extracts from both species were active against each microbial species, but the C. monspeliensis leaf ethanolic extract was much more active against several microbial species than that of C. salvifolius. For example, the C. salvifolius 70% ethanol extract showed its highest antimicrobial activity against P. aeruginosa and A. niger (MIC 3.1 mg/ml and MBC 6.3 mg/ml for both), while the C. monspeliensis extract showed much higher overall activity against E. coli, P. aeruginosa and C. albicana. (MIC 6.25 mg/ml and MBC 12.5 mg/ml for all three). In conclusion, maceration with 70% ethanol was the most efficient method for extracting total polyphenols, flavonoids, and condensed tannins from the two Cistus species, and the aqueous-ethanol extracts displayed the highest antioxidant and antimicrobial activities. Hence, the aqueousethanolic extracts of both species may be considered as potential sources of natural antioxidants and antimicrobial agents.


A composição de metabólitos secundários, atividade antioxidante e propriedades de inibição microbiana de extratos das folhas de duas espécies de Cistus; C. monspeliensis e C. salvifolius foram investigados utilizando-se três solventes de extração (etanol, hexano e água destilada). A extração com etanol foi a mais eficiente na extração de compostos fenólicos, flavonóides e taninos condensados em comparação com hexano e água destilada para ambas as espécies de Cistus. Um teste antioxidante total (TAA) e dois testes de eliminação de radicais (DPPH e ABTS) indicaram que o extrato em etanol 70% das folhas de C. salvifolius teve maior atividade antioxidante em comparação com o extrato etanólico de C. monspeliensis, enquanto o extrato aquoso de C. monspeliensis teve maior atividade antioxidante que o respectivo extrato aquoso ou o extrato etanólico de C. salvifolius. Em geral, os extratos polares foram mais ativos em ambas as espécies do que os extratos não-polares. Assim, extratos etanólico e aquoso das folhas de cada uma das espécies de Cistus foram testados quanto à sua capacidade de inibir sete cepas microbianas patogênicas, incluindo Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, e Candida albicans. Extratos etanólicos da folha de ambas as


Assuntos
Cistus , Antifúngicos , Antioxidantes
8.
J Sci Food Agric ; 93(1): 134-41, 2013 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-22674342

RESUMO

BACKGROUND: Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint. RESULTS: The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed-phase high-performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans-2-hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L(-1) NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin-3-galactoside and quercetin-3-rhamnoside. CONCLUSION: Our results confirmed the tolerance of Tunisian O. majorana plants.


Assuntos
Antioxidantes/farmacologia , Flavonoides/metabolismo , Origanum/efeitos dos fármacos , Fenóis/metabolismo , Tolerância ao Sal , Cloreto de Sódio/farmacologia , Taninos/metabolismo , Biflavonoides/metabolismo , Biflavonoides/farmacologia , Compostos de Bifenilo/metabolismo , Canadá , Flavonoides/farmacologia , Ácido Gálico/metabolismo , Ácido Gálico/farmacologia , Origanum/metabolismo , Fenóis/farmacologia , Fenilpropionatos/metabolismo , Fenilpropionatos/farmacologia , Picratos/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/metabolismo , Quercetina/metabolismo , Sais/farmacologia , Especificidade da Espécie , Estresse Fisiológico , Taninos/farmacologia , Tunísia
9.
Acta Pharm ; 62(2): 251-61, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22750822

RESUMO

O. majorana shoots were investigated for their essential oil (EO) composition. Two experiments were carried out; the first on hydroponic medium in a culture chamber and the second on inert sand in a greenhouse for 20 days. Plants were cultivated for 17 days in hydroponic medium supplemented with NaCl 100 mmol L⁻¹. The results showed that the O. majorana hydroponic medium offered higher essential oil yield than that from the greenhouse. The latter increased significantly in yield (by 50 %) under saline constraint while it did not change in the culture chamber. Under greenhouse conditions and in the absence of salt treatment, the major constituents were terpinen-4-ol and trans-sabinene hydrate. However, in the culture chamber, the major volatile components were cis-sabinene hydrate and terpinen-4-ol. In the presence of NaCl, new compounds appeared, such as eicosane, spathulenol, eugenol, and phenol. In addition, in the greenhouse, with or without salt, a very important change of trans-sabinene hydrate concentration in EO occurred, whereas in the culture chamber change appeared in cis-sabinene hydrate content.


Assuntos
Óleos Voláteis/química , Origanum/química , Origanum/crescimento & desenvolvimento , Brotos de Planta/química , Brotos de Planta/crescimento & desenvolvimento , Estresse Fisiológico , Compostos Orgânicos Voláteis/análise , Monoterpenos Bicíclicos , Ionização de Chama , Cromatografia Gasosa-Espectrometria de Massas , Hidroponia , Monoterpenos/análise , Monoterpenos/química , Monoterpenos/metabolismo , Óleos Voláteis/isolamento & purificação , Origanum/metabolismo , Brotos de Planta/metabolismo , Controle de Qualidade , Salinidade , Plantas Tolerantes a Sal/química , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/metabolismo , Estereoisomerismo , Terpenos/análise , Terpenos/química , Terpenos/metabolismo , Tunísia , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/metabolismo
10.
J Sci Food Agric ; 91(14): 2613-20, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21800320

RESUMO

BACKGROUND: The effects of salt on the essential oil yield and fatty acid composition of aerial parts of two marjoram varieties were investigated. Plants with 6 leaves were treated with NaCl (75mM). RESULTS: Salt treatment led to a reduction in aerial part growth. Salinity increased the fatty acid content more significantly in Tunisian variety (TV) than in Canadian variety (CV). CV showed an increase in double-bond index (DBI) and a decrease in malondialdehyde content under salt stress, while the opposite was observed in TV. The DBI was mainly affected by a strong reduction in oleic and linoleic acids in TV, whereas a strong stimulation of linoleic acid in CV was observed. Salt decreased and increased the essential oil yield in TV and CV respectively. The main constituents of the essential oil of TV were trans-hydrate sabinene and terpinen-4-ol, which showed a significant decrease under salt stress. In contrast, the main constituents of the essential oil of CV were sabinene and trans-hydrate sabinene, which showed a significant decrease and increase respectively under salt stress. CONCLUSION: Marjoram oil is a rich source of many compounds such as essential oils and fatty acids, but the distribution of these compounds differed significantly between the two varieties studied.


Assuntos
Ácidos Graxos/metabolismo , Óleos Voláteis/química , Origanum/metabolismo , Componentes Aéreos da Planta/metabolismo , Tolerância ao Sal , Solo/química , Estresse Fisiológico , Monoterpenos Bicíclicos , Ionização de Chama , Cromatografia Gasosa-Espectrometria de Massas , Ácido Linoleico/metabolismo , Peroxidação de Lipídeos , Malondialdeído/metabolismo , Monoterpenos/química , Monoterpenos/metabolismo , Ácido Oleico/metabolismo , Origanum/crescimento & desenvolvimento , Componentes Aéreos da Planta/crescimento & desenvolvimento , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Salinidade , Especificidade da Espécie , Estereoisomerismo , Terpenos/química , Terpenos/metabolismo , Tunísia
11.
J Agric Food Chem ; 58(8): 5122-30, 2010 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-20302375

RESUMO

Salinity inhibits plant growth due to osmotic and ionic effects. However, little is known about the impact of genotype and salinity on biochemical and molecular processes in the leafy vegetable lettuce. We report here evaluations of two lettuce types, Verte (NaCl tolerant) and Romaine (NaCl sensitive), under iso-osmotic 100 mM NaCl and 77 mM Na(2)SO(4) treatments. As compared to Romaine, NaCl-treated Verte displayed better growth, contained lower levels of inorganic cations in leaves, and possessed superior antioxidative capacity due to enhanced carotenoid and phenolics biosynthesis and more active antioxidative enzymes resulting in reduced membrane damage. Both genotypes had relatively similar growth patterns under Na(2)SO(4) treatment, but Romaine showed enhanced root lignification, greater malondialdehyde formation, and suppressed Fe-superoxide dismutase expression in roots as compared with Verte.


Assuntos
Antioxidantes/metabolismo , Lactuca/metabolismo , Cloreto de Sódio , Genótipo , Lactuca/genética , Fotoquímica , Especificidade da Espécie
12.
C R Biol ; 332(9): 784-94, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19748453

RESUMO

Potassium-sodium interaction was compared in two natural accessions of Arabidopsis thaliana, Columbia-0 and NOK2. Seedlings were grown in the presence of 0 or 50 mM NaCl and 0.1; 0.625 or 2.5 mM K(+). At the lowest K(+) concentration, salt treatment inhibited both K(+) uptake and growth. Increasing the K(+) availability did not modified salt response in Columbia-0, but restored nearly normal net K(+) uptake in NaCl condition and alleviated NaCl growth reduction in NOK2. The effect of K(+) and NaCl on transcript level of several K(+) and Na(+) transporters in both shoots and roots was assessed using semi-quantitative RT-PCR. The mRNA abundance of the NHX1 and SOS1 Na(+)/H(+) antiporters was significantly increased by 50 mM NaCl in the two accessions. NHX1, which is responsible for Na(+) sequestration into vacuoles, was more up-regulated in NOK2 leaves than in Columbia-0's in NaCl stress condition. AKT1, which is the major channel involved in K(+) absorption, was down-regulated in salt stress condition, but was not responding to K(+) treatments. Only in NOK2, SKOR and AKT2, which respectively control xylem and phloem K(+) transport, were markedly up-regulated by 2.5 mM K(+) in both roots and shoots, independently of NaCl. Phenotypic and gene expression analyses suggest that the relative salt tolerance of NOK2 is mainly due to a high ability to sequester Na(+) in the vacuole and to take up and transport K(+). Up-regulation of SKOR and AKT2 by K(+), and of NHX1 by NaCl could participate in determining this phenotype.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Potássio/metabolismo , Potássio/farmacologia , Cloreto de Sódio/farmacologia , Sódio/metabolismo , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/genética , Transporte Biológico Ativo , Meios de Cultura , Fenótipo , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , RNA/biossíntese , RNA/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa
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