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1.
J Periodontal Res ; 52(1): 122-126, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27018040

RESUMO

BACKGROUND AND OBJECTIVE: Periodontal disease has been described as playing a role in the atherosclerosis process, and its relation with intimal thickness and vascular endothelial function (EF) has been investigated. The present study sought to determine whether there are differences in parameters of arterial stiffness and EF between patients with and without severe periodontal disease (SPD). MATERIAL AND METHODS: Patients referred to the School of Dentistry University of Buenos Aires, were assessed. Demographic characteristics, atherogenic risk factors and concomitant pathologies were recorded. Patients with known cardiovascular pathology were excluded. Using carotid Doppler ultrasound an operator assessed arterial stiffness parameters: compliance, elastic modulus (EM), ß stiffness index (ßSI) and vascular EF by brachial artery flow-mediated dilatation. The patients were divided into two groups: with and without SPD. RESULTS: Forty patients were included; 60% were women; 15 were in the SPD group and 25 in the group without SPD. Respective results of the studied variables were: age 56.53 ± 17.58 vs. 51.12 ± 12.97 years (NS); probing depth 2.53 ± 1.30 (95% CI 1.81-3.25) vs. 1.25 ± 0.51 (95% CI 1.31-1.73) p = 0.02; clinical attachment level 4.80 ± 2.00 (95% CI 3.69-5.91) vs. 1.72 ± 0.93 (95% CI 1.33-2.11) p = 0.001; intimal thickness 0.10 ± 0.17 (95% CI 0.095-0.11) vs. 0.82 ± 0.18 (95% CI 0.074-0.98) (NS); EM 48.33 ± 12.53 vs. 38.86 ± 7.69 (p = 0.005); ßSI 4.21 ± 1.03 vs. 3.64 ± 1.02 (p = 0.004); EF 16.13 ± 5.02 vs. 22.76 ± 4.50 (p = 0.0003). Correlation between: EM and clinical attachment level r = 0.58 (p < 0.001), ßSI and clinical attachment level r = 0.66 (p < 0.001), EF and clinical attachment level 0.59 (p < 0.001). CONCLUSIONS: Parameters of arterial stiffness and EF were worse in patients with SPD and correlated moderately with clinical attachment level. Correlation with compliance and EF was negative.


Assuntos
Doenças Periodontais/complicações , Rigidez Vascular , Perda do Osso Alveolar/complicações , Perda do Osso Alveolar/diagnóstico por imagem , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Perda da Inserção Periodontal/complicações , Estudos Prospectivos , Radiografia Dentária
2.
Work ; 54(3): 617-30, 2016 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-27315408

RESUMO

BACKGROUND: Estimating health and safety costs in the construction industry presents various difficulties, including the complexity of cost allocation, the inadequacy of data available to managers and the absence of an accounting model designed specifically for safety cost management. Very often, the costs arising from accidents in the workplace are not fully identifiable due to the hidden costs involved. OBJECTIVE: This paper reviews some studies of occupational health and safety cost management and proposes a means of classifying these costs. METHODS: We conducted an empirical study in which the health and safety costs of 40 construction worksites are estimated. RESULTS: A new classification of the health and safety cost and its categories is proposed: Safety and non-safety costs. CONCLUSIONS: The costs of the company's health and safety policy should be included in the information provided by the accounting system, as a starting point for analysis and control. From this perspective, a classification of health and safety costs and its categories is put forward.


Assuntos
Acidentes de Trabalho/economia , Indústria da Construção/economia , Custos e Análise de Custo/classificação , Segurança/economia , Alocação de Custos , Controle de Custos , Humanos , Saúde Ocupacional/economia
3.
Braz. j. microbiol ; Braz. j. microbiol;41(2): 329-332, Apr.-June 2010. ilus
Artigo em Inglês | LILACS | ID: lil-545338

RESUMO

We report a case of cavitary pneumonia caused by N. otitidiscaviarum in a man with diabetes mellitus and thrombocytopenia treated with systemic corticosteroid. Taxonomic identification involved phenotypic testing and molecular identification that was carried out by DNA sequencing of the 16SrRNA gene.


Assuntos
Humanos , Masculino , Adulto , Corticosteroides , Sequência de Bases , Resistência Microbiana a Medicamentos , Pneumopatias , Nocardia/genética , Nocardia/isolamento & purificação , Nocardiose/diagnóstico , Nocardiose/genética , Classificação , Técnicas e Procedimentos Diagnósticos , Métodos , Fenótipo
4.
Braz J Microbiol ; 41(2): 329-32, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24031500

RESUMO

We report a case of cavitary pneumonia caused by N. otitidiscaviarum in a man with diabetes mellitus and thrombocytopenia treated with systemic corticosteroid. Taxonomic identification involved phenotypic testing and molecular identification that was carried out by DNA sequencing of the 16SrRNA gene.

5.
Transplant Proc ; 41(6): 2189-91, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19715869

RESUMO

A retrospective study was performed in liver transplant patients with high risk to develop cytomegalovirus infection (CMV D+/R-) who were treated with valgancyclovir for 3 months as prophylactic therapy. The aim of this study was to determine the safety and efficacy of prophylactic therapy with valgancyclovir. Weekly CMV antigenemia was routinely assessed during the first 3 months posttransplantation, twice a month to month 6, and monthly until the end of the first year, as well as when clinically indicated. The follow-up period was 1 year. From January 2003 to February 2007, 199 liver transplantations were performed at our institution, including 23 (11%) high-risk patients for CMV infection. Median age was 47 +/- 11.6 years. Nineteen patients (70.4%) were men. Five subjects (21.7%) developed CMV infections. Three patients with positive CMV antigenemia at 3, 4, or 6 months posttransplantation were asymptomatic, while 2 (8.7%) showed gastrointestinal CMV disease at 2 months posttransplantation or CMV hepatitis at 1 month after the end of the prophylactic therapy. Treatment with intravenous gancyclovir followed by oral valgancyclovir was successful in both patients. No opportunistic infections were observed and only 1 patient developed leukopenia as an adverse event related to valgancyclovir.


Assuntos
Antivirais/uso terapêutico , Infecções por Citomegalovirus/prevenção & controle , Ganciclovir/análogos & derivados , Transplante de Fígado/efeitos adversos , Adulto , Antivirais/efeitos adversos , Quimioprevenção/métodos , Infecções por Citomegalovirus/epidemiologia , Feminino , Ganciclovir/efeitos adversos , Ganciclovir/uso terapêutico , Humanos , Imunossupressores/uso terapêutico , Leucopenia/induzido quimicamente , Neoplasias Hepáticas/cirurgia , Transplante de Fígado/imunologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Tacrolimo/uso terapêutico , Valganciclovir
6.
Clin Microbiol Infect ; 12(8): 793-7, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16842576

RESUMO

This study describes the genetic relationships and antimicrobial resistance determinants found among 99 clinical isolates of enterococci from 15 different hospitals in Cuba. Pulsed-field gel electrophoresis SmaI analysis demonstrated a high degree of genetic diversity. A limited number of multiresistant Enterococcus faecalis clones, showing resistance to three or more families of antimicrobial agents, were detected simultaneously in different institutions, suggesting inter-hospital circulation of selected clones, and/or selection of particular clones following their introduction into the hospital environment. Antimicrobial resistance determinants, including erm(B), aac(6')-aph(2'), aph(3'), ant(6), vanB (E. faecalis) and vanA (Enterococcus faecium) were detected by PCR in various isolates.


Assuntos
Enterococcus/efeitos dos fármacos , Enterococcus/genética , Aminoglicosídeos/metabolismo , Aminoglicosídeos/farmacologia , Farmacorresistência Bacteriana/genética , Humanos
8.
Hum Reprod ; 20(9): 2517-22, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15919777

RESUMO

BACKGROUND: Previous observations have addressed a decreased male:female ratio associated with smoking. Our aim was to assess whether this effect is observed at the spermatozoa or at the early embryo development. METHODS: We retrospectively assessed smoking intake habits of 56 couples included in our preimplantation genetic diagnosis (PGD) program. Three groups were established according to male or female cigarette consumption per day: non-smokers, smokers (1-19 cigarettes per day) and heavy smokers (> or =20 cigarettes per day). Fluorescence in-situ hybridization (FISH) was performed on ejaculated sperm samples to analyse chromosomes X and Y. On day 3, embryos were also analysed. Additionally, sperm samples from four heavy smoking and four non-smoking donors were prospectively analysed before and after capacitation. RESULTS: FISH on spermatozoa revealed no statistical differences in the Y:X ratio between the three groups. However, in the PGD study, in male heavy smokers, the XY:XX embryo ratio was decreased compared with non-smokers (22:47 versus 80:71; P = 0.0057). The smoking condition of the female partner had no significant effect on embryo XY:XX ratio, but for non-smoking females with a heavy smoking partner, the ratio was decreased (P = 0.0018) compared with non-smoking males. In heavy smoking donors a decreased of Y:X ratio was observed after swim-up with a statistically significant difference of ratios (P = 0.021). CONCLUSIONS: Smoking habits of males do not have an effect on the percentage of X- and Y-bearing spermatozoa on ejaculated samples. However, male heavy smokers produce an increased incidence of female embryos that could be related to an enrichment of X spermatozoa after swim-up in patients with high tobacco consumption.


Assuntos
Blastocisto , Razão de Masculinidade , Fumar/epidemiologia , Espermatozoides , Adulto , Cromossomos Humanos X , Cromossomos Humanos Y , Feminino , Humanos , Hibridização in Situ Fluorescente , Incidência , Masculino , Gravidez , Estudos Retrospectivos
9.
Br J Dermatol ; 151(4): 886-90, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15491432

RESUMO

BACKGROUND: Tinea capitis is the most common type of dermatophytosis in children, but is uncommon in the first year of life. OBJECTIVES: To review clinical, mycological and epidemiological data in a series of 10 infants aged under 1 year diagnosed as having tinea capitis in three Spanish hospitals between 1998 and 2002. METHODS: A retrospective case note study. RESULTS: There were six boys and four girls with a mean of age 7 months (range 1.5-12). All the children were born in Spain, but in five cases the parents were immigrants from Africa. In these cases the isolated dermatophytes were two Trichophyton tonsurans, one T. verrucosum and two Microsporum audouinii. Four autochthonous cases were caused by M. canis and one by M. audouinii (but this one was in contact with African immigrants). In two of the five cases produced by anthropophilic dermatophytes other family members were infected by the same fungus. Most cases were treated successfully with griseofulvin. CONCLUSIONS: Although tinea capitis is rare in infants in their first year of life, the condition should be investigated if scaling and/or alopecia are present. A thorough epidemiological study of other family members is mandatory.


Assuntos
Tinha do Couro Cabeludo/diagnóstico , Antifúngicos/uso terapêutico , Arthrodermataceae/classificação , Arthrodermataceae/isolamento & purificação , Feminino , Humanos , Lactente , Masculino , Estudos Retrospectivos , Tinha do Couro Cabeludo/tratamento farmacológico , Tinha do Couro Cabeludo/microbiologia
10.
J Chemother ; 16(3): 230-7, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15330317

RESUMO

We have studied the prevalence of the different macrolide, lincosamide, streptograminB (MLS(B)) phenotypes among clinical Staphylococcus aureus isolates erythromycin- and/or oxacillin-resistant; and also the activity of other antimicrobial agents including telithromycin, quinupristin/dalfopristin, linezolid, aminoglycosides, chloramphenicol and vancomycin. We found that 64.86% of S. aureus were oxacillin-resistant. While the most prevalent MLS(B) phenotype among methicillin-resistant S. aureus (MRSA) was constitutive MLS(B) (cMLS) (83%), among methicillin-susceptible S. aureus (MSSA) it was inducible MLS(B) (iMLS(B)) (90%). Kanamycin resistance was more frequent than resistance to other aminoglycosides, being 100% for MRSA. Telithromycin was only active against iMLS(B), MS and erythromycin-susceptible isolates, although resistance rates were found among iMLS(B) MSSA (2.78%). Quinupristin/dalfopristin showed greater activity, with resistance rates of 2.5% for MRSA and 1.53% for MSSA. Both vancomycin and linezolid were fully active against all the isolates tested, with the highest MIC value being 2 microg/ml and 4 microg/ml, respectively. Among MRSA strains, 81.67% displayed resistance to five or more antimicrobials. This multiresistance was more frequently found among cMLS(B) strains (96.38% MRSA resistant to 6-9 agents).


Assuntos
Acetamidas/farmacologia , Cetolídeos , Macrolídeos/farmacologia , Oxazolidinonas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Virginiamicina/análogos & derivados , Virginiamicina/farmacologia , Farmacorresistência Bacteriana Múltipla , Humanos , Linezolida , Testes de Sensibilidade Microbiana , Estudos de Amostragem , Sensibilidade e Especificidade , Espanha , Staphylococcus aureus/isolamento & purificação
11.
J Antimicrob Chemother ; 53(6): 1068-71, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15117921

RESUMO

OBJECTIVES: The aim of this study was to determine the roles of mutations in the gyrA and parC genes and the overexpression of efflux pump(s) as mechanisms of resistance to quinolones. Forty-five Yersinia enterocolitica O:3 clinical isolates (41 nalidixic acid-resistant, three nalidixic acid-susceptible and one nalidixic acid-resistant strain obtained in vitro) were analysed. RESULTS: All the nalidixic acid-resistant strains showed mutations in the gyrA gene and none in the parC gene. The presence of the inhibitor produced decreases in the MIC values of nalidixic acid by two to six serial dilution steps in 37 of the 41 nalidixic acid-resistant strains. Meanwhile, the MIC value of ciprofloxacin was affected in two strains whose values diminished three serial dilution steps. The nalidixic acid-resistant mutant obtained in vitro was also affected by the inhibitor decreasing the MIC value of nalidixic acid three serial dilutions steps whereas the MICs for the nalidixic acid-susceptible strains were not affected. CONCLUSIONS: Our results show that the high level of resistance to nalidixic acid is likely due to an overexpression of an efflux pump plus a mutation in the gyrA gene, whereas decreased susceptibility to ciprofloxacin is only associated with the presence of a mutation in the gyrA gene.


Assuntos
Anti-Infecciosos/farmacologia , Quinolonas/farmacologia , Yersinia enterocolitica/efeitos dos fármacos , Yersinia enterocolitica/genética , Ciprofloxacina/farmacologia , DNA Girase/genética , DNA Topoisomerase IV/genética , Dipeptídeos/farmacologia , Farmacorresistência Bacteriana , Humanos , Testes de Sensibilidade Microbiana , Mutação/genética , Ácido Nalidíxico/farmacologia , Espanha , Yersiniose/microbiologia
12.
J Clin Microbiol ; 41(10): 4876-8, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14532248

RESUMO

Forty-six Yersinia enterocolitica O:3 clinical isolates resistant to nalidixic acid were studied. The use of molecular typing techniques, other indicators of resistance patterns, the plasmid profile, and the presence of genes that encode aminoglycoside-modifying enzyme production suggested to us a clonal dissemination of the studied strains.


Assuntos
Anti-Infecciosos/farmacologia , Farmacorresistência Bacteriana , Ácido Nalidíxico/farmacologia , Yersiniose/epidemiologia , Yersinia enterocolitica/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Humanos , Testes de Sensibilidade Microbiana , Nucleotidiltransferases/genética , Plasmídeos/genética , Yersiniose/microbiologia , Yersinia enterocolitica/genética
13.
Eur J Clin Microbiol Infect Dis ; 21(8): 624-5, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12226697

RESUMO

The study presented here examined the efficacy of a commercially available qualitative immunochromatographic assay for detecting Cryptosporidium oocysts in stool samples. A total of 75 samples were tested, including 50 positive for Cryptosporidium spp. by acid-fast stain, 20 positive for other parasites ( Blastocystis hominis, Endolimax nana, Entamoeba coli, Giardia lamblia, Ascaris lumbricoides, Strongyloides stercoralis and Trichuris trichiura), and five negative samples. The observed sensitivity was 98%, while specificity was 100%; the detection threshold was near 1000 oocysts/ml. Correctly diagnosed positive samples included Cryptosporidium parvum genotypes 1 and 2, whereas the single false-negative sample corresponded to a Cryptosporidium meleagridis infection.


Assuntos
Criptosporidiose/diagnóstico , Cryptosporidium parvum/isolamento & purificação , Fezes/microbiologia , Testes Imunológicos/normas , Oocistos/isolamento & purificação , Animais , Criptosporidiose/imunologia , Cryptosporidium parvum/imunologia , Humanos , Testes Imunológicos/métodos , Oocistos/imunologia , Sensibilidade e Especificidade
14.
Neuropharmacology ; 42(5): 619-25, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11985819

RESUMO

Benzodiazepines are anxiolytic, anticonvulsant, sedative and hypnotic compounds usually prescribed on a long-term basis. Chronic treatment with these compounds induces tolerance, which has been extensively attributed to modifications in the GABAergic neurotransmission. However, a compensatory increase in the excitatory response, named as an oppositional response, has also been put forward as a means for explaining such tolerance. Changes in the excitatory neurotransmission have been found in withdrawn rats after a long treatment with benzodiazepines but these modifications have not been conclusively studied during tolerance. In this work we studied several parameters of the glutamatergic neurotransmission in rats made tolerant to the sedative effect of 3 mg/kg (i.p.) of lorazepam (LZ). We found a decrease in the affinity of cortical NMDA receptors for (3)H-glutamate (K(D): 124.4 +/- 13.3 nM in tolerant rats, 71.6 +/- 10.4 nM in controls, P<0.05) together with a decrease in the in vitro 60 mM K(+)-stimulated cortical glutamate release (59+/- 12% vs. 153 +/- 38%, tolerant rats vs. controls, P<0.05). We conclude that tolerance to the sedative effect of LZ correlates with a decreased sensitivity for glutamate that may in turn diminish the cortical response to a chemical stimulus. Our findings constitute an evidence against the oppositional model of pharmacodynamic tolerance in this experimental condition.


Assuntos
Córtex Cerebral/metabolismo , Ácido Glutâmico/metabolismo , Hipnóticos e Sedativos/farmacologia , Lorazepam/farmacologia , Animais , Sítios de Ligação , Córtex Cerebral/efeitos dos fármacos , Relação Dose-Resposta a Droga , Tolerância a Medicamentos/fisiologia , Masculino , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Ratos , Ratos Wistar , Receptores de N-Metil-D-Aspartato/metabolismo
15.
Behav Pharmacol ; 13(1): 87-92, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11990723

RESUMO

In previous studies we have demonstrated a possible interaction between the gamma-aminobutyric acid (GABA)ergic and opioid systems involved in the antinociceptive effect of the GABAB agonist, baclofen (BAC). In addition, we have demonstrated that BAC was able to prevent the morphine (MOR) withdrawal syndrome in female, as well as male mice. On the other hand, seasonal variations have been observed in some MOR effects. In the present study, we analysed the effects of BAC on naloxone (NAL)-precipitated withdrawal, during two different seasons. The experiments were performed during two seasons: spring-summer (SS) and autumn-winter (AW) for two years, on male Swiss-Webster albino mice (27-33 g). Mice were rendered dependent by intraperitoneal (i.p.) injection of MOR (2mg/kg), twice daily for 9 days. On the tenth day the dependent animals were divided into two groups: one received NAL (6mg/kg, i.p.) 60 min after the last dose of MOR, to develop the NAL-precipitated withdrawal; the other group received BAC (2mg/kg, i.p.) followed by NAL (6mg/kg, i.p.), injected 30 and 60 min after the last dose of MOR, respectively. Behavioural signs were recorded in the open field for 30 min. Although there were seasonal variations in the MOR withdrawal syndrome, we found that BAC prevents MOR withdrawal irrespective of seasonal variation.


Assuntos
Baclofeno/farmacologia , Morfina/efeitos adversos , Estações do Ano , Síndrome de Abstinência a Substâncias/fisiopatologia , Animais , Nível de Alerta/efeitos dos fármacos , Feminino , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia
16.
Rev Esp Quimioter ; 15(4): 335-40, 2002 Dec.
Artigo em Espanhol | MEDLINE | ID: mdl-12587038

RESUMO

The in vitro activity of posaconazole against Candida species isolated from blood cultures and the influence of incubation time was studied and compared with that of fluconazole. A total of 112 isolates were studied: 32 Candida albicans, 33 C. parapsilosis, 17 C. tropicalis, 8 C. glabrata, 8 C. guilliermondii, 3 C. famata, 2 C. lusitaniae, 1 C. lipolytica, 1 C. inconspicua, 1 C. lambica, 3 Saccharomyces cerevisiae, 1 Blastoschizomyces capitatus, 1 Geotricum spp. and 1 Pichia omheri. The MIC was obtained using the M27-A microdilution method described by the NCCLS for Candida spp. and Cryptococcus neoformans. The species most susceptible to posaconazole were C. parapsilosis (MCI90 0.016 mg/l), C. guilliermondii (MIC90 0.12 mg/l), C. glabrata (MCI90 0.5 mg/l) and Candida spp. (MCI90 0.25 mg/l). However, this azole did not improve the activity of fluconazole against C. tropicalis (MIC90 8 mg/l) and C. albicans (MCI90 mg/l). The time of reading was important in the detection of resistance, as the number of strains resistant to fluconazole or posaconazole was higher at 48 hours than at 24 hours for C. albicans and C. tropicalis. All the other species of Candida were susceptible at both reading times.


Assuntos
Sangue/microbiologia , Triazóis/farmacologia , Leveduras/efeitos dos fármacos , Técnicas Bacteriológicas , Humanos , Leveduras/isolamento & purificação
17.
Rev Esp Quimioter ; 15(2): 152-7, 2002 Jun.
Artigo em Espanhol | MEDLINE | ID: mdl-12582444

RESUMO

In order to identify any changes in the incidence of Salmonella enterica serotypes and their resistance to a variety of antimicrobial agents, we conducted a retrospective study of all the strains isolated from stool samples at Hospital Clínico Universitario Lozano Blesa in Zaragoza from 1997 to 2000. We observed an increase in the number of isolates of Salmonella and Campylobacter and a decrease in other enteropathogens. Enteritidis was the most frequently isolated serotype (55.2%), showing an increasing tendency (from 44.1% in 1997 to 60.6% in 2000). Hadar, glostrup and virchow showed the highest rate of resistance to nalidixic acid. Enteritidis also showed an important increase in resistance to nalidixic acid (from 17.6% in 1997 to 41.4% in 2000). Typhimurium showed the highest resistance levels to ampicillin, chloramphenicol and cotrimoxazole. No resistance to fluoroquinolones or to cefotaxime was detected, with the exception of 0.5% of the S. enteritidis strains, which showed resistance to fluoroquinolones.


Assuntos
Farmacorresistência Bacteriana , Salmonella enterica/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Espanha
19.
Mol Plant Microbe Interact ; 14(10): 1178-88, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11605957

RESUMO

The composition of antioxidant enzymes, especially superoxide dismutase (SOD), was studied in one nontransgenic and three transgenic lines of nodulated alfalfa plants. Transgenic lines overproduced MnSOD in the mitochondria of nodules and leaves (line 1-10), MnSOD in the chloroplasts (line 4-6), and FeSOD in the chloroplasts (line 10-7). In nodules of line 10-7, the absence of transgene-encoded FeSOD activity was due to a lack of mRNA, whereas in nodules of line 4-6 the absence of transgene-encoded MnSOD activity was due to enzyme inactivation or degradation. Transgenic alfalfa showed a novel compensatory effect in the activities of MnSOD (mitochondrial) and FeSOD (plastidic) in the leaves, which was not caused by changes in the mRNA levels. These findings imply that SOD activity in plant tissues and organelles is regulated, at least partially, at the posttranslational level. All four lines had low CuZnSOD activities and an abundant FeSOD isozyme, especially in nodules, indicating that FeSOD performs important antioxidant functions other than the scavenging of superoxide radicals generated in photosynthesis. This was confirmed by the detection of FeSOD cDNAs and proteins in nodules of other legumes such as cowpea, pea, and soybean. The cDNA encoding alfalfa nodule FeSOD was characterized and the deduced protein found to contain a plastid transit peptide. A comparison of sequences and other properties reveals that there are two types of FeSODs in nodules.


Assuntos
Medicago sativa/enzimologia , Folhas de Planta/enzimologia , Raízes de Plantas/enzimologia , Superóxido Dismutase/genética , Sequência de Aminoácidos , Antioxidantes/metabolismo , Sequência de Bases , Catalase/metabolismo , Cloroplastos/metabolismo , DNA Complementar/química , DNA Complementar/genética , Regulação Enzimológica da Expressão Gênica , Isoenzimas , Medicago sativa/genética , Mitocôndrias/metabolismo , Dados de Sequência Molecular , Peroxidases/metabolismo , Filogenia , Folhas de Planta/genética , Raízes de Plantas/genética , Raízes de Plantas/microbiologia , Plantas Geneticamente Modificadas , Processamento de Proteína Pós-Traducional , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Análise de Sequência de DNA , Superóxido Dismutase/metabolismo , Simbiose , Transcrição Gênica
20.
Mol Plant Microbe Interact ; 14(10): 1189-96, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11605958

RESUMO

The mitochondria of legume root nodules are critical to sustain the energy-intensive process of nitrogen fixation. They also generate reactive oxygen species at high rates and thus require the protection of antioxidant enzymes and metabolites. We show here that highly purified mitochondria from bean nodules (Phaseolus vulgaris L. cv. Contender x Rhizobium leguminosarum bv. phaseoli strain 3622) contain ascorbate peroxidase primarily in the inner membrane (with lesser amounts detected occasionally in the matrix), guaiacol peroxidases in the outer membrane and matrix, and manganese superoxide dismutase (MnSOD) and an ascorbate-regenerating system in the matrix. This regenerating system relies on homoglutathione (instead of glutathione) and pyridine nucleotides as electron donors and involves the enzymes monodehydroascorbate reductase, dehydroascorbate reductase, and homoglutathione reductase. Homoglutathione is synthesized in the cytosol and taken up by the mitochondria and bacteroids. Although bacteroids synthesize glutathione, it is not exported to the plant in significant amounts. We propose a model for the detoxification of peroxides in nodule mitochondria in which membrane-bound ascorbate peroxidase scavenges the peroxide formed by the electron transport chain using ascorbate provided by L-galactono-1,4-lactone dehydrogenase in the inner membrane. The resulting monodehydroascorbate and dehydroascorbate can be recycled in the matrix or cytosol. In the matrix, the peroxides formed by oxidative reactions and by MnSOD may be scavenged by specific isozymes of guaiacol peroxidase, ascorbate peroxidase, and catalase.


Assuntos
Antioxidantes/metabolismo , Fabaceae/metabolismo , Glutationa/análogos & derivados , Mitocôndrias/metabolismo , Raízes de Plantas/metabolismo , Ascorbato Peroxidases , Catalase/metabolismo , Citosol/enzimologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Fabaceae/enzimologia , Glutationa/biossíntese , Isoenzimas/metabolismo , Malato Desidrogenase/metabolismo , Proteínas de Membrana/metabolismo , NADH Desidrogenase/metabolismo , NADH NADPH Oxirredutases/metabolismo , Fixação de Nitrogênio/fisiologia , Oxirredutases/metabolismo , Peptídeo Sintases/metabolismo , Peroxidase/metabolismo , Peroxidases/metabolismo , Raízes de Plantas/enzimologia , Raízes de Plantas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Simbiose
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