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1.
Eur Child Adolesc Psychiatry ; 29(2): 227-238, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31302773

RESUMO

Despite the occurrence of several earthquakes, only a few studies were conducted in Italy on the psychological impact in children and adolescents, with data mostly collected within one year after the disaster. This cross-sectional study aimed at exploring the prevalence of both post-traumatic stress disorder (PTSD) and emotional/behavioral difficulties, as well as at identifying their main predictors, among youths 2 years after the earthquake that hit Northern Italy in 2012. 682 children and adolescents (9-14 years) living in two districts (earthquake zone vs control zone) were administered an exposure questionnaire, the UCLA PTSD-Index for DSM-IV, and the Strengths and Difficulties Questionnaire (SDQ) and 1162 parents were assessed through the Symptom Checklist-90 (SCL-90). The prevalence of a likely PTSD in the earthquake zone was 1.9% (4.4% near the epicenter) and the total PTSD score in the affected area was significantly higher than in the control zone. 14.9% of youths living in the earthquake zone had a borderline/abnormal SDQ total difficulties score and 87.5% of youth with a likely PTSD also had a SDQ total score in the borderline/abnormal range. Regression analysis showed that the number of lifetime traumatic events (e.g., death of a relative) was the best predictor of children/adolescents psychological difficulties 2 years after the earthquake, followed by severity of exposure (personal injuries and losses) and parental psychopathology. Despite some limitations, this study highlights that youths may exhibit PTSD symptoms years after disasters, often in comorbidity with behavioral/emotional difficulties, stressing the need for long-term surveillance and interventions in exposed populations.


Assuntos
Terremotos/mortalidade , Psicopatologia/métodos , Transtornos de Estresse Pós-Traumáticos/psicologia , Adolescente , Criança , Estudos Transversais , Feminino , História do Século XXI , Humanos , Itália/epidemiologia , Masculino , Inquéritos e Questionários , Fatores de Tempo
2.
Breast ; 29: 90-5, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27476083

RESUMO

PURPOSE: To evaluate toxicity in breast cancer patients treated with anthracycline and taxane based chemotherapy and whole breast hypofractionated radiotherapy, and to identify the risk factors for toxicity. METHODS AND MATERIALS: 537 early breast cancer patients receiving hypofractionated radiotherapy after conservative surgery were enrolled from April 2009 to December 2014, in an Italian cancer institute. The dose was 42.4 Gy in 16 daily fractions, 2.65 Gy per fraction. The boost to the tumor bed was administered only in grade III breast cancer patients and in patients with close or positive margins. Acute and late toxicity were prospectively assessed during and after radiotherapy according to RTOG scale. The impact of patients clinical characteristics, performed treatments and dose inhomogeneities on the occurrence of an higher level of acute skin toxicity and late fibrosis has been evaluated by univariate and multivariate analysis. RESULTS: The mean age was 74 (range 46-91 yrs). 27% of patients received boost. 22% of cases (n = 119) received also chemotherapy. The median follow-up was 32 months. G1 and G2/G3 acute skin toxicity were 61.3% and 20.5% and G1 and G2/G3 late fibrosis 12.6% and 4.3% respectively. Chemotherapy (p = 0.04), diabetes (p = 0.04) and boost administration (p < 0.01) were found to be statistically significant on the occurrence of late fibrosis, but a multivariate analysis did not show any factors connected. The boost administration (p < 0.01), the breast volume (p = 0.05), dose inhomogeneities (p < 0.01) and boost volume (p = 0.04) were found to be statistically significant as concerns the occurrence of acute skin reaction at the univariate analysis, but only the boost administration (p = 0.02), at multivariate analysis. CONCLUSIONS: The results of our study, according to the large randomized trials, confirmed that hypofractionated whole breast irradiation is safe, and only the boost administration seems to be an important predictor for toxicity. Chemotherapy does not impact on acute and late skin toxicity.


Assuntos
Antineoplásicos/efeitos adversos , Neoplasias da Mama/terapia , Quimiorradioterapia Adjuvante/efeitos adversos , Hipofracionamento da Dose de Radiação , Lesões por Radiação/etiologia , Idoso , Idoso de 80 Anos ou mais , Antraciclinas/efeitos adversos , Mama/patologia , Mama/efeitos da radiação , Neoplasias da Mama/patologia , Hidrocarbonetos Aromáticos com Pontes/efeitos adversos , Relação Dose-Resposta à Radiação , Feminino , Fibrose , Seguimentos , Humanos , Pessoa de Meia-Idade , Análise Multivariada , Estadiamento de Neoplasias , Estudos Prospectivos , Reirradiação/efeitos adversos , Fatores de Risco , Pele/efeitos da radiação , Taxoides/efeitos adversos
3.
J Clin Oncol ; 14(5): 1421-30, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8622055

RESUMO

PURPOSE: To compare, in a prospective randomized trial, the efficacy of two different sequences of mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) and doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) chemotherapy in untreated advanced Hodgkin's disease. PATIENTS AND METHODS: From June 1982 to September 1990, 427 consecutive previously untreated patients with pathologic stage IB, IIA bulky, IIB, III (A and B), and IV (A and B) disease were prospectively randomized to receive two different sequences of MOPP and ABVD for a minimum of six cycles followed by radiotherapy (median dose, 30 Gy) to the nodal site(s) of pretreatment bulky disease. Of 415 assessable patients, 211 received one cycle of MOPP monthly, alternated with one cycle of ABVD (alternating regimen), and 204 patients received one-half cycle of MOPP alternated with one-half cycle of ABVD within a 1-month period (hybrid regimen). RESULTS: The complete remission (CR) rate was 91% with the alternating regimen and 89% with the hybrid regimen. At 10 years, the freedom-from-progression (FFP) rate was 67% versus 69% and the overall survival (OS) rate was 74% versus 72%, respectively. After attainment of CR, 85 patients relapsed in nodal (n = 60) versus extranodal with or without nodal (n = 25) sites. In patients given consolidative radiation because of bulky lymphoma, the true recurrence rate was 13%. A total of 23 second malignancies (6%) were documented, including 11 cases of acute nonlymphocytic leukemia. No cases of congestive heart failure attributable to doxorubicin or pulmonary toxicity related to bleomycin were documented. CONCLUSION: By delivering MOPP and ABVD, it is possible to cure approximately 70% of patients with advanced Hodgkin's disease. The two different drug sequences yielded superimposable results.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Doença de Hodgkin/tratamento farmacológico , Adolescente , Adulto , Idoso , Bleomicina/administração & dosagem , Terapia Combinada , Dacarbazina/administração & dosagem , Doxorrubicina/administração & dosagem , Feminino , Doença de Hodgkin/patologia , Doença de Hodgkin/radioterapia , Humanos , Masculino , Mecloretamina/administração & dosagem , Pessoa de Meia-Idade , Prednisona/administração & dosagem , Procarbazina/administração & dosagem , Estudos Prospectivos , Indução de Remissão , Terapia de Salvação , Vimblastina , Vincristina/administração & dosagem
4.
J Clin Oncol ; 15(2): 528-34, 1997 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9053474

RESUMO

PURPOSE: This study analyzed long-term results in patients with Hodgkin's disease who were resistant to or relapsed after first-line treatment with MOPP and ABVD. Response to salvage treatments and prognostic factors were also evaluated. PATIENTS AND METHODS: The study population included 115 refractory or relapsed patients among a total of 415 patients treated with alternating or hybrid MOPP-ABVD followed by radiotherapy (25 to 30 Gy) to initial bulky sites. The median follow-up duration of the present series was 91 months. Thirty-nine of 115 patients (34%) showed disease progression while on primary treatment (induction failures); 48 relapsed after complete remissions that lasted < or = 12 months and 28 after complete remission that lasted more than 12 months from the end of all treatments. RESULTS: At 8 years, the overall survival rate was 27%, being 54% and 28% in patients whose initial complete remission was longer or shorter than 12 months, respectively, and 8% in induction failures (P < .001). Response to first-line chemotherapy and disease extent at first progression significantly influenced long-term results, as well as the incidence and duration of complete remission. CONCLUSION: The present data confirm previous observations that showed the main prognostic factors to influence outcome after salvage treatment are response duration to first-line therapy and disease extent at relapse. The results indicate that patients who relapse after the alternating MOPP/ABVD regimen have a prognosis similar to that of patients who relapse after a four-drug regimen (MOPP or ABVD alone). Re-treatment with initial chemotherapy seems the treatment of choice for patients who relapse after an initial complete remission that lasts greater than 12 months, while the real impact of high-dose chemotherapy or new regimens should be assessed in resistant patients.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Doença de Hodgkin/tratamento farmacológico , Adulto , Bleomicina/administração & dosagem , Dacarbazina/administração & dosagem , Doxorrubicina/administração & dosagem , Feminino , Humanos , Masculino , Mecloretamina/administração & dosagem , Valor Preditivo dos Testes , Prednisona/administração & dosagem , Procarbazina/administração & dosagem , Prognóstico , Terapia de Salvação , Análise de Sobrevida , Falha de Tratamento , Resultado do Tratamento , Vimblastina/administração & dosagem , Vincristina/administração & dosagem
5.
Chem Commun (Camb) ; 51(27): 5917-20, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25730473

RESUMO

Bacterial biosensors are simple, cost-effective and efficient analytical tools for detecting bioavailable heavy metals in the environment. This work presents the design, construction and calibration of a novel whole-cell fluorescent biosensory device that, simultaneously and with high sensitivity, reports the presence of toxic mercury, lead, cadmium and/or gold ions in aqueous samples. This bio-reporter can be easily applied as an immediate alerting tool for detecting the presence of harmful pollutants in drinking water.


Assuntos
Técnicas Biossensoriais/métodos , Cádmio/análise , Água Potável/química , Ouro/análise , Chumbo/análise , Mercúrio/análise , Poluentes Químicos da Água/análise , Sequência de Bases , Cátions Bivalentes , Expressão Gênica , Genes Reporter , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Dados de Sequência Molecular , Plasmídeos/química , Plasmídeos/metabolismo , Regiões Promotoras Genéticas , Salmonella enterica/genética , Salmonella enterica/metabolismo
6.
Int J Radiat Oncol Biol Phys ; 30(4): 813-9, 1994 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-7525516

RESUMO

PURPOSE: The study was undertaken to evaluate the long-term results in a favorable subset of patients with pathological Stage IA-IIA treated with irradiation alone. METHODS AND MATERIALS: One hundred and forty-seven adults with laparotomy- Staged IA-IIA "favorable" Hodgkin's disease were treated with primary subtotal nodal irradiation. Patients with infradiaphragmatic presentation were irradiated through paraortic and inguino-iliac node chains (inverted Y field) followed by prophylactic mediastinal and supraclavicular fields. RESULTS: Actuarial overall survival (OS) at 7 years (median follow-up 77 months) was: 93% for the whole series, 94% for Stage I, and 92% for Stage II. The freedom from first progression (FFP) (80% for the whole series) showed a statistically significant difference (p = 0.008) between Stage I (88%) and Stage II (71%). By univariate analysis, stage alone had an independent prognostic significance for OS and FFP. Of the 29 relapsed patients, 8 were previously classified as Stage I and 21 as Stage II; 16 of 29 (55%) of the relapses occurred in the pelvis and 9 in extranodal sites. After salvage treatment with chemotherapy all patients achieved a second complete remission. Seven second malignancies (two acute nonlymphocytic leukemias, one preleukemic syndrome, and four solid tumors) have been detected so far. Hypothyroidism was observed in 16% of patients and a reversible pulmonary restrictive syndrome in 14% of cases, respectively. CONCLUSIONS: Within 7 years from radiation therapy, about one-quarter of the patients with Stage II disease will experience a relapse and need intensive salvage chemotherapy. This is not invariably successful and safe, for it may be complicated by either acute or potentially fatal long-term adverse effects, such as second malignancies and cardiac or pulmonary sequelae, in about 5% of patients. The high frequency of relapse in Stage IIA patients suggests a combined modality approach with relatively short-term chemotherapy not including alkylating agents.


Assuntos
Doença de Hodgkin/patologia , Doença de Hodgkin/radioterapia , Adolescente , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Bleomicina/administração & dosagem , Terapia Combinada , Ciclofosfamida/administração & dosagem , Dacarbazina/administração & dosagem , Doxorrubicina/administração & dosagem , Epirubicina/administração & dosagem , Etoposídeo/administração & dosagem , Feminino , Seguimentos , Doença de Hodgkin/complicações , Humanos , Masculino , Mecloretamina/administração & dosagem , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Segunda Neoplasia Primária/patologia , Prednisona/administração & dosagem , Procarbazina/administração & dosagem , Prognóstico , Fatores de Risco , Terapia de Salvação , Vimblastina , Vincristina/administração & dosagem
7.
Res Microbiol ; 145(5-6): 473-80, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-7855434

RESUMO

Salmonella typhimurium is a facultative intracellular pathogen that is able to survive in a wide variety of inhibitory and nutritionally deprived host environments. The ability to survive under such hostile conditions, which are often encountered during the course of infection, contributes to its pathogenic properties. Some of the virulence determinants of S. typhimurium are under the transcriptional control of the PhoPQ two-component regulatory system. Several virulence phenotypes have been associated with mutations in the phoPQ operon including the inability to survive within macrophages and increased susceptibility to antimicrobial peptides and acid pH. Only 25% of PhoP-modulated genes are involved in virulence and the phoPQ operon is present in both pathogenic and non-pathogenic microbes. These data suggest that PhoP is not exclusively involved in virulence and that it is required for the physiological control of activities common to other bacteria.


Assuntos
Proteínas de Bactérias/genética , Salmonella typhimurium/genética , Técnicas In Vitro , Regulon/genética , Salmonella typhimurium/patogenicidade , Virulência
8.
Am J Clin Oncol ; 23(1): 18-21, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10683067

RESUMO

Radiotherapy (RT) in patients with favorable-stage Hodgkin's disease can induce clinical and subclinical evidence of pulmonary damage lasting over the years. In this study, we monitored 36 patients with stage IA-IIA Hodgkin's disease treated with subtotal nodal RT. The planned dose of RT was 40 Gy to 44 Gy to the involved areas and 36 Gy to the adjacent uninvolved areas. Pulmonary function was evaluated by chest radiograph, spirometric parameters, arterial blood gas analysis, and single-breath CO transfer factor (DLCO). The tests were performed before and at the end of irradiation, and during the follow-up 1 and 3 to 5 years after the treatment. At the end of RT, we found a significant decrease of total lung capacity, vital capacity, forced expiratory volume in 1 second, residual volume, and DLCO. Spirometric parameters improved during the follow-up period, whereas the decline of DLCO (-6.4%) was persistent. No correlation was found between mantle RT dose and DLCO changes. Four patients showed a decline of DLCO of >20% from pretreatment values but only one was symptomatic. Our study confirms that RT induces a pulmonary-restrictive disease at a subclinical level that seems to be reversible in the majority of patients.


Assuntos
Doença de Hodgkin/radioterapia , Pneumonite por Radiação , Adolescente , Adulto , Idoso , Feminino , Doença de Hodgkin/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Pneumonite por Radiação/diagnóstico , Pneumonite por Radiação/fisiopatologia , Dosagem Radioterapêutica , Indução de Remissão , Testes de Função Respiratória
9.
Tumori ; 81(4): 265-7, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-8540124

RESUMO

To investigate the relation between estrogen receptor (ER) status and timing of relapse, we retrospectively studied two groups of patients (200 cases in each group) who underwent radical mastectomy and developed an early relapse (within 3 years of the surgery) or a long-term relapse (more than 8 years after surgery). One-hundred and eighty-two (91%) patients who developed a long-term relapse were ER-positive (ER+), whereas only 64% of patients who developed an early relapse were ER+ (P < 0.001), supporting the hypothesis that a long-term relapse is more frequently associated with an ER+ tumor. A review of the literature, which indicated that a long-term relapse arises more frequently in patients in whom a partial hormone control is maintained, seems to support this finding, albeit the presence of 18 ER-negative (ER-) cases in our study. However, this apparent contradictory observation could be explained by the fact that 12 of our patients were in premenopause and that ER-status could have been false ER- results due to the binding of endogenous estradiol to ER.


Assuntos
Neoplasias da Mama/diagnóstico , Neoplasias da Mama/ultraestrutura , Receptores de Estrogênio/análise , Neoplasias da Mama/cirurgia , Feminino , Humanos , Valor Preditivo dos Testes , Pré-Menopausa , Prognóstico , Recidiva , Fatores de Tempo
10.
J Biol Chem ; 264(35): 21112-5, 1989 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-2687273

RESUMO

The N-terminal sequence of the spinach chloroplast reductase-binding protein was determined. The sequence is the same one of a 16.5-kDa polypeptide described as a component of the oxygen-evolving system. Antibodies against both proteins are equivalent as shown by immunoblots, Ouchterlony assays, precipitation of reductase-binding protein complex, and agglutination of thylakoids partially depleted of reductase. These results suggest both proteins are identical. Exposure of the binding protein on the stromal side of thylakoids is supported by agglutination of thylakoids partially depleted of reductase, proteolysis by trypsin, and by accessibility to Fab of anti-binding protein. The latter prevents rebinding of reductase supporting the functional role of the binding protein (16.5 kDa).


Assuntos
Clorofila/metabolismo , Cloroplastos/enzimologia , Ferredoxina-NADP Redutase/metabolismo , Proteínas de Membrana/metabolismo , NADH NADPH Oxirredutases/metabolismo , Fotossíntese , Proteínas de Plantas/metabolismo , Plantas/enzimologia , Sequência de Aminoácidos , Proteínas de Cloroplastos , Cinética , Complexos de Proteínas Captadores de Luz , Dados de Sequência Molecular , Peso Molecular , Complexo de Proteínas do Centro de Reação Fotossintética , Homologia de Sequência do Ácido Nucleico
11.
Plant Physiol ; 90(2): 372-5, 1989 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16666777

RESUMO

Monospecific polyclonal antibodies against thylakoid ferredoxin-NADP(+) oxidoreductase and its binding protein from Spinacia oleracea were used to detect the presence of these proteins in different higher plants, including C(3), C(4), and Crassulacean acid metabolism species. A remarkable conservation of antigenic determinants in all the species analyzed was demonstrated for both the reductase and its binding protein. The association of these polypeptides in a complex was detected by immunoprecipitation.

12.
J Bacteriol ; 178(23): 6796-801, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8955299

RESUMO

The PhoP/PhoQ two-component system of Salmonella typhimurium governs transcription of some 25 loci in response to the extracellular concentration of Mg2+. We have now identified one of these loci as pmrCAB, which codes for a two-component system that mediates resistance to the antibiotic polymyxin B. Transcription of seven of 25 PhoP-activated loci was dependent on a functional PmrA protein, the response regulator of the PmrA/PmrB system. Expression of the PmrA-dependent loci was induced by either Mg2+ limitation or mild acidification, whereas transcription of a PmrA-independent gene was activated by Mg2+ limitation but not acid pH. Induction of PmrA-activated genes by Mg2 limitation required the PhoP and PhoQ proteins. In contrast, the acid-mediated activation of PmrA-regulated genes occurred in strains that were missing either one of these proteins. Transcriptional regulation by a cascade of two-component systems allows pathogenic bacteria to express their virulence determinants in response to a broader spectrum of environmental cues.


Assuntos
Proteínas de Bactérias/fisiologia , Regulação Bacteriana da Expressão Gênica , Salmonella typhimurium/genética , Fatores de Transcrição/fisiologia , Proteínas de Bactérias/genética , Meios de Cultura , Concentração de Íons de Hidrogênio , Magnésio/farmacologia , Mutagênese Insercional , Óperon , Salmonella typhimurium/metabolismo , Salmonella typhimurium/patogenicidade , Fatores de Transcrição/genética
13.
Plant Physiol ; 82(2): 499-502, 1986 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16665058

RESUMO

Thylakoid membrane preparations obtained from mechanically disrupted (sonicated) cells of the cyanobacterium Anabaena sp. strain 7119 show a membrane-bound ferredoxin-NADP(+) oxidoreductase (EC 1.18.1.2) as determined either by specific antibodies or by using the ferredoxin-dependent NADPH-cytochrome c reductase activity, which is a specific test for this enzyme. However, in contrast with higher plant thylakoids, a low yield of the cyanobacterial reductase-only about 20% of the total amount of this protein estimated in whole cell homogenates-was obtained as a membrane-bound form when Mg(2+) was present during the disruption treatment. It is noteworthy that the addition of water-soluble nonionic polymers, namely polyethylene glycol and polyyinylpyrrolidone, dramatically increased the yield of the thylakoid-bound reductase, reaching values up to 80 to 85% of the total enzyme. Using these thylakoid membrane preparations, a quantitative determination of the reductase has been performed for the first time for cyanobacterial thylakoids. The value determined by immunoelectrophoresis-from 8 to 10 nanomoles per micromole of chlorophyll-is clearly higher than those reported for chloroplast thylakoids.

14.
J Bacteriol ; 179(22): 7040-5, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9371451

RESUMO

The PmrA-PmrB two-component system of Salmonella typhimurium controls resistance to the peptide antibiotic polymyxin B and to several antimicrobial proteins from human neutrophils. Amino acid substitutions in the regulatory protein PmrA conferring resistance to polymyxin lower the overall negative charge of the lipopolysaccharide (LPS), which results in decreased bacterial binding to cationic polypeptides and increased bacterial survival within human neutrophils. We have now identified three PmrA-activated loci that are required for polymyxin resistance. These loci were previously shown to be necessary for growth on low-Mg2+ solid media, indicating that LPS modifications that mediate polymyxin resistance are responsible for the adaptation to Mg2+-limited environments. Conditions that promote transcription of PmrA-activated genes--growth in mildly acidic pH and micromolar Mg2+ concentrations--increased survival in the presence of polymyxin over 16,000-fold in a wild-type organism but not in a mutant lacking pmrA. Our experiments suggest that low pH and low Mg2+ concentrations may induce expression of PmrA-activated genes within phagocytic cells and promote bacterial resistance to host antimicrobial proteins. We propose that the LPS is a Mg2+ reservoir and that the PmrA-controlled LPS modifications neutralize surface negative charges when Mg2+ is transported into the cytoplasm during growth in Mg2+-limited environments.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Resistência Microbiana a Medicamentos , Magnésio/metabolismo , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Alelos , Antibacterianos/farmacologia , Proteínas de Bactérias/fisiologia , Regulação Bacteriana da Expressão Gênica , Concentração de Íons de Hidrogênio , Lipopolissacarídeos/metabolismo , Testes de Sensibilidade Microbiana , Peptídeos/metabolismo , Polimixinas/farmacologia , Ligação Proteica , Salmonella typhimurium/metabolismo , Transcrição Gênica
15.
J Biol Chem ; 275(30): 22948-54, 2000 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-10807931

RESUMO

The PhoP/PhoQ two-component system controls the expression of essential virulence traits in the pathogenic bacterium Salmonella enterica serovar Typhimurium. Environmental deprivation of Mg(2+) activates the PhoP/PhoQ signal transduction cascade, which results in an increased expression of genes necessary for survival inside the host. It was previously demonstrated that the interaction of Mg(2+) with the periplasmic domain of PhoQ promotes a conformational change in the sensor protein that leads to the down-regulation of PhoP-activated genes. We have now examined the regulatory effect of Mg(2+) on the putative activities of the membrane-bound PhoQ. We demonstrated that Mg(2+) promotes a phospho-PhoP phosphatase activity in the sensor protein. This activity depends on the intactness of the conserved His-277, suggesting that the phosphatase active site overlaps the H box. The integrity of the N-terminal domain of PhoQ was essential for the induction of the phosphatase activity, because Mg(2+) did not stimulate the release of inorganic phosphate from phospho-PhoP in a fusion protein that lacks this sensing domain. These findings reveal that the sensor PhoQ harbors a phospho-PhoP phosphatase activity, and that this phosphatase activity is the target of the extracellular Mg(2+)-triggered regulation of the PhoP/PhoQ system.


Assuntos
Proteínas de Bactérias/metabolismo , Magnésio/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Salmonella enterica/metabolismo , Sequência de Bases , Primers do DNA , Fosforilação , Salmonella enterica/enzimologia
16.
J Bacteriol ; 177(15): 4364-71, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7543474

RESUMO

The Salmonella typhimurium PhoP-PhoQ two-component regulatory system controls the expression of several genes, some of which are necessary for virulence. During a screening for PhoP-regulated genes, we identified the phoPQ operon as a PhoP-activated locus. beta-Galactosidase activity originating from phoPQ-lac transcriptional fusions required the presence of both the transcriptional regulator PhoP and its cognate sensor-kinase PhoQ. At low concentrations, PhoQ stimulated expression of phoPQ-lac transcriptional fusions. However, larger amounts of PhoQ protein without a concomitant increase in PhoP failed to activate phoPQ-lac fusions. Two different transcripts are produced from the phoPQ operon during exponential growth. These transcripts define two promoters: phoPp1, which requires both PhoP and PhoQ for activity and which is environmentally regulated, and phoPp2, which remains active in the absence of PhoP and PhoQ but which is slightly stimulated by these proteins. The pattern of transcriptional autoregulation was also observed at the protein level with anti-PhoP antibodies. In sum, autoregulation of the phoPQ operon provides several levels of control for the PhoP-PhoQ regulon. First, environmental signals would stimulate PhoQ to phosphorylate the PhoP protein that is produced at basal levels from the PhoP-PhoQ-independent promoter. Then, phospho-PhoP would activate transcription of phoPp1, resulting in larger amounts of PhoP and PhoQ and increased expression of PhoP-activated genes. A return to basal levels could be mediated by a posttranscriptional mechanism by which translation of the mRNA produced from phoPp1 is inhibited.


Assuntos
Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica/fisiologia , Óperon , Salmonella typhimurium/genética , Transcrição Gênica/fisiologia , Proteínas de Bactérias/biossíntese , Sequência de Bases , Clonagem Molecular , Elementos de DNA Transponíveis , Homeostase/genética , Óperon Lac , Modelos Genéticos , Dados de Sequência Molecular , Mutação , Conformação de Ácido Nucleico , Regiões Promotoras Genéticas , RNA Bacteriano/genética , RNA Mensageiro/análise , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética
17.
Cell ; 84(1): 165-74, 1996 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-8548821

RESUMO

Ions are not traditionally thought to act as first messengers in signal transduction cascades. However, while searching for genes regulated by the PhoP/PhoQ virulence regulatory system of Salmonella typhimurium, we recovered two loci whose expression is controlled by the concentration of Mg2+. To determine whether Mg2+ is the signal modulating the whole PhoP/PhoQ system, we evaluated the gene expression pattern of six PhoP-activated genes. Growth in physiological concentrations of divalent cations repressed transcription of PhoP-activated genes and rendered wild-type Salmonella phenotypically PhoP-. Mg2+ changed the conformation of the periplasmic domain of PhoQ, identifying this protein as a Mg2+ sensor. A mutation in the sensing domain of PhoQ altered the set point for Mg2+ and rendered Salmonella avirulent.


Assuntos
Magnésio/farmacologia , Salmonella typhimurium/fisiologia , Salmonella typhimurium/patogenicidade , Transdução de Sinais/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Sequência de Bases , Cátions/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Concentração de Íons de Hidrogênio , Cinética , Dados de Sequência Molecular , Mutação/fisiologia , Peptídeos/fisiologia , Fenótipo , Conformação Proteica , Sensibilidade e Especificidade , Fatores de Transcrição/genética , Virulência
18.
J Bacteriol ; 175(5): 1514-23, 1993 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8444812

RESUMO

A recombinant lambda phage which was able to propagate in groE mutants of Escherichia coli was isolated from a Chromatium vinosum genomic DNA library. A 4-kbp SalI DNA fragment, isolated from this phage and subcloned in plasmid vectors, carried the C. vinosum genes that allowed lambda growth in these mutants. Sequencing of this fragment indicated the presence of two open reading frames encoding polypeptides of 97 and 544 amino acids, respectively, which showed high similarity to the molecular chaperones GroES and GroEL, respectively, from several eubacteria and eukaryotic organelles. Expression of the cloned C. vinosum groESL genes in E. coli was greatly enhanced when the cells were transferred to growth temperatures that induce the heat shock response in this host. Coexpression in E. coli of C. vinosum groESL genes and the cloned ribulose bisphosphate carboxylase/oxygenase genes from different phototrophic bacteria resulted in an enhanced assembly of the latter enzymes. These results indicate that the cloned DNA fragment encodes C. vinosum chaperonins, which serve in the assembly process of oligomeric proteins. Phylogenic analysis indicates a close relationship between C. vinosum chaperonins and their homologs present in pathogenic species of the gamma subdivision of the eubacterial division Proteobacteria.


Assuntos
Proteínas de Bactérias/genética , Chaperoninas/genética , Chromatium/genética , Proteínas de Choque Térmico/genética , Sequência de Aminoácidos , Sequência de Bases , Evolução Biológica , Clonagem Molecular , DNA Bacteriano , Escherichia coli , Proteínas de Escherichia coli , Genes Bacterianos , Teste de Complementação Genética , Dados de Sequência Molecular , Mapeamento por Restrição , Homologia de Sequência de Aminoácidos , Temperatura
19.
Int J Syst Bacteriol ; 44(3): 527-33, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7520741

RESUMO

The essential GroEL proteins represent a subset of molecular chaperones ubiquitously distributed among species of the eubacterial lineage, as well as in eukaryote organelles. We employed these highly conserved proteins to infer eubacterial phylogenies. GroEL from the species analyzed clustered in distinct groups in evolutionary trees drawn by either the distance or the parsimony method, which were in general agreement with those found by 16S rRNA comparisons (i.e., proteobacteria, chlamydiae, bacteroids, spirochetes, firmicutes [gram-positive bacteria], and cyanobacteria-chloroplasts). Moreover, the analysis indicated specific relationships between some of the aforementioned groups which appeared not to be clearly defined or controversial in rRNA-based phylogenetic studies. For instance, a monophyletic origin for the low-G+C and high-G+C subgroups among the firmicutes, as well as their specific relationship to the cyanobacteria-chloroplasts, was inferred. The general observations suggest that GroEL proteins provide valuable evolutionary tools for defining evolutionary relationships among the eubacterial lineage of life.


Assuntos
Bactérias/classificação , Bactérias/genética , Proteínas de Bactérias/genética , Evolução Biológica , Proteínas de Choque Térmico/genética , Bactérias/química , Composição de Bases , Chaperonina 60 , Chlamydia/classificação , Chlamydia/genética , Cianobactérias/classificação , Cianobactérias/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Helicobacter pylori/classificação , Helicobacter pylori/genética , Filogenia , Porphyromonas gingivalis/classificação , Porphyromonas gingivalis/genética , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Spirochaetales/classificação , Spirochaetales/genética
20.
Cell ; 103(1): 113-25, 2000 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-11051552

RESUMO

Iron is essential for all organisms but can be toxic in excess. Iron homeostasis is typically regulated by cytoplasmic iron binding proteins, but here we describe a signal transduction system (PmrA/PmrB) that responds to extracytoplasmic ferric iron. Iron promoted transcription of PmrA-activated genes and resistance to the antibiotic polymyxin in Salmonella. The PmrB protein bound iron via its periplasmic domain which harbors two copies of the sequence ExxE, a motif present in the Saccharomyces FTR1 iron transporter and in mammalian ferritin light chain. A pmrA mutant was hypersensitive to killing by iron but displayed wild-type resistance to a variety of oxidants, suggesting PmrA/PmrB controls a novel pathway mediating the avoidance of iron toxicity.


Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Espaço Extracelular/metabolismo , Ferro/metabolismo , Ferro/farmacologia , Salmonella enterica/efeitos dos fármacos , Transdução de Sinais/fisiologia , Proteínas de Bactérias/genética , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/genética , Resistência Microbiana a Medicamentos/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/genética , Proteínas de Ligação ao Ferro , Fenótipo , Polimixinas/farmacologia , Estrutura Terciária de Proteína/genética , Salmonella enterica/genética , Salmonella enterica/metabolismo , Fatores de Transcrição/genética , Transcrição Gênica/genética , Proteínas de Ligação a Transferrina
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