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1.
J Laryngol Otol ; 137(12): 1300-1311, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36999550

RESUMO

OBJECTIVE: This review evaluated the safety profile and efficacy of probiotics in chronic rhinosinusitis and was registered with Prospero (Centre for Reviews and Dissemination number: 42020193529). METHOD: Literature databases were searched through inception to August 2022. Randomised, controlled trials exploring adjunctive probiotics in adult chronic rhinosinusitis patients were included. From 948 records screened, 4 randomised, controlled trials were included. RESULTS: Probiotics-associated adverse effects comprised epistaxis and abdominal pain. No reduction in Sino-Nasal Outcome Test values before 4 weeks (p = 0.58) or beyond 8 weeks (p = 0.08) of treatment or reduction of severe symptom frequency (p = 0.75) was observed. Symptom relapse in probiotic-treated patients was significantly lower across all timepoints (p = 0.045). Lower sinusitis relapse risks during treatment (risk ratio = 0.49; p = 0.019) and 8 months post-treatment (risk ratio = 0.56, p = 0.013) were observed. Probiotics demonstrated potential in improving Sino-Nasal Outcome Test symptom subscales, including sleep, psychological and rhinology subscales. CONCLUSION: The optimal mode of probiotic administration, treatment duration and target patient subgroups requires further study to evaluate the utility of probiotics.


Assuntos
Probióticos , Rinite , Sinusite , Adulto , Humanos , Administração Intranasal , Doença Crônica , Probióticos/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Recidiva , Rinite/tratamento farmacológico , Sinusite/tratamento farmacológico
2.
J Craniomaxillofac Surg ; 49(1): 24-28, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33279397

RESUMO

PURPOSE: The aim of this study was to compare the efficacy of dextrose prolotherapy with that of occlusal splints in treating internal derangement of the temporomandibular joint. PATIENTS AND METHODS: A total of 34 patients with temporomandibular joint internal derangement classed as Wilkes stages II or III were recruited for the study, and were randomly divided into study and control groups with 17 patients each. The patients in these control and study groups were treated with splints and prolotherapy, respectively. Outcome parameters, such as pain, mouth opening, clicking and deviation, were assessed using the Helkimo clinical dysfunction index for a review period of 1 year. RESULTS: Nine patients in the study group had complete absence of pain, compared with only one patient in the control group. The results showed that patients who received prolotherapy demonstrated improvement in pain (p < 0.001), mouth opening (p = 0.032), and clicking (p < 0.001), but no significant difference in deviation was observed between the groups after 1 year (p = 0.862). CONCLUSION: Prolotherapy was found to be superior in providing long-term clinical relief, with reduction in pain and clicking along with improved mouth opening.


Assuntos
Luxações Articulares , Proloterapia , Transtornos da Articulação Temporomandibular , Humanos , Placas Oclusais , Amplitude de Movimento Articular , Articulação Temporomandibular , Transtornos da Articulação Temporomandibular/tratamento farmacológico , Resultado do Tratamento
3.
J Stomatol Oral Maxillofac Surg ; 118(6): 359-362, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28838774

RESUMO

Radiation therapy for the treatment of head and neck cancer can injure normal tissues and have devastating side effects. Hyperbaric oxygen (HBO) is known to reduce the severity of radiation-induced injury by promoting wound healing. While most of the research in literature has focused on its efficacy in osteonecrosis, HBO has other proven benefits as well. The aim of this review was to identify the various benefits of hyperbaric oxygen therapy in patients who have undergone radiation for head and neck cancer. An electronic database search was carried out to identify relevant articles and selected articles were reviewed in detail. The quality of evidence for each benefit, including preserving salivary gland function, preventing osteonecrosis, dental implant success, and overall quality of life, was evaluated. Evidence showed that HBO was effective in improving subjective symptoms of xerostomia, swallowing, speech and overall quality of life. There was no conclusive evidence to show that HBO improved implant survival, prevented osteonecrosis, or improved salivary gland function. The high costs and accessibility of HBO therapy must be weighed against the potential benefits to each patient.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Oxigenoterapia Hiperbárica/métodos , Lesões por Radiação/prevenção & controle , Lesões por Radiação/terapia , Implantação Dentária/métodos , Implantação Dentária/normas , Implantação Dentária/estatística & dados numéricos , Implantes Dentários/normas , Implantes Dentários/estatística & dados numéricos , Neoplasias de Cabeça e Pescoço/epidemiologia , Humanos , Oxigenoterapia Hiperbárica/estatística & dados numéricos , Osteonecrose/epidemiologia , Osteonecrose/etiologia , Osteonecrose/prevenção & controle , Osteonecrose/terapia , Qualidade de Vida , Lesões por Radiação/epidemiologia , Lesões por Radiação/etiologia , Glândulas Salivares/fisiologia , Glândulas Salivares/efeitos da radiação , Extração Dentária/estatística & dados numéricos , Xerostomia/epidemiologia , Xerostomia/etiologia , Xerostomia/prevenção & controle , Xerostomia/terapia
4.
Int J Oral Maxillofac Surg ; 44(7): 871-5, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25721919

RESUMO

The aim of this randomized controlled trial was to assess the effectiveness of fibrin sealants in achieving haemostasis and wound closure following mandibular third molar extraction, in comparison with conventional suturing. Thirty patients with bilateral mandibular third molar impactions were recruited for the study. Using a split-mouth study design, wound closure following extraction was done using fibrin sealant on the study side and suturing on the control side. Sample allocation was done by simple randomization. The primary outcome measures were (1) the time taken to achieve wound closure and haemostasis and (2) postoperative mouth opening, pain, and swelling. Data analysis involved descriptive statistics and paired t-tests (P<0.05). IBM SPSS software (v.20.0) was used for the data analysis. The study group demonstrated a statistically significant reduction in duration to achieve haemostasis (1.2 vs. 251.9s; P<0.001) and wound closure (152.8 vs. 328.8s; P<0.001) in comparison with the control group. The study group also exhibited significantly reduced pain scores (2.0 vs. 3.5; P<0.001) and increased post-surgical mouth opening (P<0.001). No adverse effects of fibrin sealant were observed. In conclusion, fibrin sealant is a superior intraoral wound closure and haemostatic agent and a worthy alternative to suturing.


Assuntos
Adesivo Tecidual de Fibrina/uso terapêutico , Dente Serotino/cirurgia , Dente Impactado/cirurgia , Feminino , Hemostasia Cirúrgica , Humanos , Masculino , Dente Serotino/diagnóstico por imagem , Medição da Dor , Estudos Prospectivos , Radiografia Panorâmica , Técnicas de Sutura , Extração Dentária , Dente Impactado/diagnóstico por imagem
5.
J Maxillofac Oral Surg ; 13(4): 444-50, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26225009

RESUMO

PURPOSE: To evaluate the efficacy of low level laser therapy (LLLT) in the treatment of temporomandibular disorders (TMD) in relation to pain intensity, tender points, joint sounds and jaw movements. MATERIALS AND METHODS: Twenty patients received 6 sessions of LLLT (3 times a week for 2 weeks) with semiconductive diode laser (gallium arsenide; 904 nm, 0.6 W, 60 s, 4 J/cm(2)). Pain intensity, number of tender points, joint sounds and active range of motion were assessed before and immediately after each session and after 1, 2 weeks, 1, 3 and 6 months. RESULTS: Statistically significant results were achieved in all study parameters. CONCLUSION: LLLT promoted satisfactory results in reducing the pain intensity, number of tender points, joint sounds and improvement in the range of jaw motion. Hence it is an effective and efficient treatment method for TMDs.

6.
Indian J Dent Res ; 22(5): 713-5, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22406719

RESUMO

Accidental entry of foreign bodies into the oro-facial region could be due to trauma, therapeutic interventions or iatrogenic. Various foreign bodies and locations have been reported, for example, wood in the orbit, impression material in the maxillary sinus, tooth fragments in the orbit. All these cases presented with inflammatory reaction and formation of infected granuloma, pus discharging sinus and serious complications like intra-cranial abscesses. Foreign bodies sometimes migrate within the tissues and become symptomatic after a certain period of time. In these cases, it is very difficult to correlate the direct relation between the suspected foreign bodies with the present clinical symptoms. The removal of foreign bodies is often a surgical challenge due to a combination of difficulty in access and close anatomical relationship to vital structures. To prevent complications, foreign bodies should be diagnosed and removed on time.


Assuntos
Queixo , Corpos Estranhos/diagnóstico , Seio Maxilar , Pescoço , Acidentes , Acidentes de Trânsito , Adolescente , Adulto , Queixo/patologia , Seguimentos , Granuloma de Corpo Estranho/diagnóstico , Humanos , Incisivo/lesões , Masculino , Seio Maxilar/patologia , Pessoa de Meia-Idade , Pescoço/patologia , Supuração , Tampões de Gaze Cirúrgicos/efeitos adversos , Avulsão Dentária/diagnóstico , Madeira/efeitos adversos
7.
Indian J Dent Res ; 21(3): 360-3, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20930345

RESUMO

OBJECTIVES: To determine the awareness amongst dental students, practitioners and maxillofacial surgeons the role of folic acid in the prevention of CLAP and its clinical use. MATERIALS AND METHODS: Questionnaire based study involving a sample base of 1100, comprising of dental students, practitioners and specialist maxillofacial surgeons. RESULTS: hundred percent of the sample population were aware of CLAP disorders, of which 9.5 % believed that CLAP could be prevented. 3.8 % of the population were able to correlate folic acid to CLAP while a negligible 0.03 % could provide the dosage. CONCLUSION: Educating healthcare providers and, in turn, the prospective parents on benefits folic acid would not only help in reducing the incidence of CLAP but also significantly influence the economics of the patients afflicted with CLAP disorders.


Assuntos
Processo Alveolar/anormalidades , Fenda Labial/prevenção & controle , Fissura Palatina/prevenção & controle , Educação em Odontologia , Ácido Fólico/uso terapêutico , Complexo Vitamínico B/uso terapêutico , Consanguinidade , Odontólogos , Educação de Pós-Graduação em Odontologia , Feminino , Ácido Fólico/administração & dosagem , Aconselhamento Genético , Testes Genéticos , Humanos , Educação de Pacientes como Assunto , Gravidez , Complicações na Gravidez/prevenção & controle , Estudantes de Odontologia , Transtornos Relacionados ao Uso de Substâncias/prevenção & controle , Cirurgia Bucal/educação , Inquéritos e Questionários , Complexo Vitamínico B/administração & dosagem
8.
Plant Cell Rep ; 15(12): 980-5, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24178287

RESUMO

Mature de-embryonated cotyledons with intact proximal end of Vigna unguiculata were cultured on B5 basal medium containing varying concentrations of BAP. Thirty-six percent of the explants produced shoots on B5 medium supplemented with 8× 10(-6) M BAP. Cotyledon explants were pre-incubated for 24 h, inoculated with A. tumefaciens pUCD2614 carrying pUCD2340, co-cultivated for 48 h and transferred to hygromycin-B (25 mg/l) containing shoot induction medium. Approximately 15-19% of the explants produced shoots on the selection medium. The elongated shoots were subsequently rooted on B5 basal medium containing hygromycin. The transgenic plants were later established in pots. The presence of hpt gene in the transgenic plants was confirmed by Southern blot hybridization.

9.
Indian J Biochem Biophys ; 27(1): 1-4, 1990 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-2187796

RESUMO

The alteration of photosynthetic membrane proteins in relation to the disappearance of pigments during the heterotrophic growth of Chlorella protothecoides was investigated. Chlorophylls and certain polypeptides associated with the LHC II disappeared after 50 hr of heterotrophic growth but the 24 kDa apoprotein constituting LHC II was not affected. Immunological analysis indicated that the chlorophylls and the light harvesting complex proteins of the thylakoid membranes are not tightly coupled and the latter is retained in its native form irrespective of the presence or absence of the former. The circumstantial evidence that the other photosynthetic membrane polypeptides are degraded along with the pigments due to increased proteolytic activity in the rapidly dividing heterotrophic cells indicate that chlorophyll synthesis is not a pre-requisite for the synthesis of the LHC II apoprotein.


Assuntos
Chlorella/análise , Clorofila/análise , Proteínas de Plantas/análise , Técnicas Imunológicas , Complexos de Proteínas Captadores de Luz , Complexo de Proteínas do Centro de Reação Fotossintética
10.
J Biol Chem ; 263(11): 5104-9, 1988 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-3356681

RESUMO

The light-dependent protein synthesis occurring in chloroplasts isolated from the leaves of 7-day-old Vigna sinensis responded to heat shock with the induction of a set of four heat shock proteins (HSPs). The synthesis of these four HSPs at the elevated temperature was transcriptionally regulated, and all of them were found to be thylakoid membrane-bound. The synthesis of these chloroplast-coded HSPs was also observed in etioplasts during protein synthesis at the elevated temperatures with the exogenously added ATP. The in vivo induction of these plastid-coded HSPs was observed only in the leaves subjected to gradual increase in temperature but not in leaves subjected to rapid heat shock. Further, the in vitro synthesis of these plastid-coded HSPs was seen only in chloroplasts isolated from the control or from leaves subjected to gradual increase in temperature and not in chloroplasts isolated from leaves subjected to rapid heat shock. Taken together these observations suggest that in V. sinensis, the plastid genome contains a definite heat shock response and the in vivo expression of this response corresponds to the gradual rise in temperature normally occurring under field conditions.


Assuntos
Cloroplastos/metabolismo , Proteínas de Choque Térmico/biossíntese , Eletroforese em Gel de Poliacrilamida , Fluorometria , Peso Molecular , Sementes/metabolismo , Temperatura
11.
Arch Biochem Biophys ; 260(1): 277-84, 1988 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2829731

RESUMO

A Mg2+ dependent inorganic pyrophosphatase from chloroplasts of Sorghum vulgare has been purified 275-fold to electrophoretic purity with an overall recovery of about 25% activity. Estimations of native and monomeric relative molecular weights by size exclusion chromatography and denaturing electrophoresis suggest that the holoenzyme is a monomer of 42 +/- 1.5 kDa. A high specificity for tetrasodium pyrophosphate (PPi) as substrate has been observed, as the other phosphoesters tested were virtually unaffected. The Mg2+:PPi ratio of 5:1 at pH 8.0 shifts to 2.5:1.0 at pH 9.0 and 10:1 at pH 7.0. None of the divalent cations tested could substitute for Mg2+. Further, in the presence of Mg2+, these divalent cations inhibit the catalytic hydrolysis of PPi. EDTA rapidly and irreversibly inactivates the purified enzyme in a biphasic manner. Of the metabolites tested, Pi and L-malate significantly inhibited the catalytic activity of the enzyme. Malate inhibits the enzyme through an allosteric mechanism. A Hill plot of this inhibition shows that at least two molecules of malate bind to each molecule of the purified enzyme. The likely physiological significance of this result is discussed.


Assuntos
Cloroplastos/enzimologia , Magnésio/fisiologia , Poaceae/enzimologia , Pirofosfatases/isolamento & purificação , Cátions Bivalentes , Concentração de Íons de Hidrogênio , Cinética , Peso Molecular , Proteínas de Vegetais Comestíveis/isolamento & purificação , Especificidade por Substrato
12.
Photosynth Res ; 19(1-2): 129-52, 1988 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24425371

RESUMO

Isolated chloroplasts show substantial rates of protein synthesis when illuminated. This 'in organello' protein synthesis system has been advantageously utilised to elucidate the coding capacity of chloroplast and the regulation of chloroplast genes. The system is also being used recently to transcribe and translate homologous and heterologous templates. In this mini-review, we attempt to critically ecaluate the available literature and present the current and the prospective lines of research.

13.
Biochem Biophys Res Commun ; 135(1): 248-55, 1986 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-3954772

RESUMO

Etioplasts were isolated from dark grown cucumber cotyledons pretreated with kinetin and gibberellic acid. When incubated in a cofactor enriched medium these etioplasts incorporated [35S] methionine into a hot trichloroacetic acid-insoluble fraction; this incorporation was linear for 8 h of incubation and was inhibited by chloramphenicol but not by cycloheximide. Over the same time period, the etioplasts showed continued linear synthesis of the chlorophyll precursors protochlorophyllide, Mg-protoporphyrin and protoporphyrin IX. Analysis of products of in vitro protein synthesis by etioplasts and cotyledons showed the thylakoid membrane polypeptide profiles to be identical. Continued incorporation of [35S] methionine into the large subunit of ribulose bisphosphate carboxylase/oxygenase (RuBisCO) for 8 h has been confirmed further by immunoprecipitation with anti-spinach RuBisCO. This competent in vitro translation system should be useful for future studies of chloroplast protein synthesis and gene expression.


Assuntos
Clorofila/biossíntese , Cloroplastos/metabolismo , Biossíntese de Proteínas , Aminoácidos/metabolismo , Sistema Livre de Células , Cloranfenicol/farmacologia , Cicloeximida/farmacologia , Proteínas de Membrana/biossíntese , Peso Molecular , Plantas , Pirróis/biossíntese , Tetrapirróis
14.
Biochem Biophys Res Commun ; 126(3): 1114-21, 1985 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-3884002

RESUMO

Studies on the appearance of various electron transport functions were followed during greening of etiolated cucumber cotyledons. Appearance of dichlorodimethoxy-p-benzoquinone, dimethyl quinone, tetramethyl-p-phenylenediamine, dichlorophenol indophenol and ferricyanide Hill reactions were observed after 8h of greening. However, photoreduction of methyl viologen (MV) and nicotinamide adenine dinucleotide phosphate (NADP) was observed from 2h of greening. Variable fluorescence, which is a direct indication of water-splitting function, was observed from 2h of greening in cotyledons, thylakoid membranes and photosystem II (PSII) particles. The decrease in variable fluorescence in the presence of MV (due to rapid reoxidation of Q-) observed from early stages of greening confirmed the photoreduction of MV by PSII. The early development of water-splitting function was further confirmed by the abolition of variable fluorescence in thylakoid membranes and PSII particles by heat treatment and concomittant loss of light dependent oxygen uptake in the presence of MV in heat treated chloroplasts. However, the photoreduction of MV and NADP was insensitive to intersystem electron transport inhibitors, dichlorophenyl dimethylurea or dibromomethyl isopropyl-p-benzoquinone till 8h of greening. Though the oxidation of intersystem electron carrier cytochrome f was observed from early stages of greening, the reduction of cytochrome f was not observed till 8h of greening. All these observations confirm that during early stages of greening MV and NADP are photoreduced by PSII without the involvement of intersystem electron carriers or the collaboration of PSI. Since these observations are at variance with the currently prevalent concept (Z-Scheme) of the photosynthetic generation of reducing power, which requires definite collaboration of the two photosystems, an alternate electron flow pathway is proposed.


Assuntos
Clorofila/metabolismo , Cloroplastos/metabolismo , NADP/metabolismo , Paraquat/metabolismo , Proteínas de Plantas/metabolismo , Plantas/metabolismo , Clorofila/biossíntese , Fluorescência , Luz , Complexos de Proteínas Captadores de Luz , Oxirredução , Consumo de Oxigênio , Complexo de Proteínas do Centro de Reação Fotossintética , Complexo de Proteína do Fotossistema I , Complexo de Proteína do Fotossistema II , Sementes
15.
Biochem Biophys Res Commun ; 125(3): 988-95, 1984 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-6393986

RESUMO

Direct radioisotopic evidence for the polypeptides associated with oxygen evolution in a non-destructive approach by comparing the polypeptides of photosystem II (PS II) particles in etioplasts that lack O2 evolution with that of chloroplasts that exhibit high rates of oxygen evolution is reported. Polypeptide analysis by coomassie blue staining revealed that 32, 23 and 15 kDa proteins were absent in etioplast particles but developed in chloroplast PS II particles after illumination. However, a strikingly different picture was obtained when labelled polypeptides were analyzed from the fluorograph. While the new proteins identified by coomassie blue staining were also labelled, intensely labelled major polypeptides of molecular range 40, 41, 43 kD and minor polypeptides of molecular range 47, 48, 51 kD were observed in chloroplast PS II particles but not in etioplasts or etioplast particles; these labelled polypeptides were so prominent that they could be identified even in thylakoid membranes.


Assuntos
Clorofila/análise , Proteínas de Plantas/análise , Cloroplastos/análise , Complexos de Proteínas Captadores de Luz , Oxigênio , Complexo de Proteínas do Centro de Reação Fotossintética , Complexo de Proteína do Fotossistema II , Espectrometria de Fluorescência
17.
Planta ; 157(2): 105-10, 1983 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24264063

RESUMO

Palisade and spongy-parenchyma cells were isolated from the leaves of a number of mesomorphic dicotyledons by simply brushing the upper and lower sides, respectively, of the leaves with nylon brushes. Cross-contamination with the opposite cell type was minimal and both cell types were photosynthetically as active as leaf discs. The rates and early products of CO2 incorporation in the two cell types isolated from Zinnia elegans Jacq. plants grown in full natural light were the same, indicating that the photosynthetic physiology of the two cell types is quite similar.

18.
Plant Physiol ; 70(3): 815-22, 1982 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16662581

RESUMO

Cell suspension cultures were established from the callus proliferation of leaf explants of 10- to 12-day-old seedlings of the peanut (Arachis hypogaea L. var. TMV-3). The cells could be cultivated in both agitated and still media, the latter promoting more of chlorophyll (Chl) synthesis. High Chl content (210-240 micrograms Chl per gram fresh weight), yield of free and pipetable cells, presence of all the pigments in the same ratio as that of the leaf tissue, and high rates of O(2) evolution (140-170 micromoles O(2) per milligram Chl per hour) were some of the desirable features of the still-grown cell cultures. However, considerable variations with regard to the above characters were observed between the cell cultures of different varieties of the peanut.O(2) evolution by the cultured cells was dependent on exogenous supply of HCO(3) (-). A well-developed photosynthetic apparatus as evidenced from photosystem I and photosystem II activities of the isolated chloroplasts and variable fluorescence measurements with the cell cultures was further documented by electron microscopic evidence of distinct granal stackings in chloroplasts and sodium dodecyl sulfate-polyacrylamide gel separation of thylakoid membranes into P700 Chl a protein complex and light-harvesting Chl a/b complex. Evidence is presented for the relative increase in the Chl associated with P700 Chl a protein complex in contrast to the light-harvesting Chl a/b complex in the cultured cells as compared to intact leaf.

19.
Plant Physiol ; 70(3): 823-6, 1982 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16662582

RESUMO

The relative transport of photosynthetic and dark carboxylation products in photoheterotrophic cells of Arachis hypogaea L. var. TMV-3 at varied phases of growth were determined. Despite the presence of an equally competent photosynthetic apparatus as determined from (14)CO(2) incorporation rates in the dark and light, pulse-chase experiments revealed little or no change in the radioactivity of the C(3) intermediates but rapid disappearance of label from the dark carbon assimilates (malate and other tricarboxylic acid cycle intermediates) with a simultaneous increase in the aminoacid pool in early log-phase (10 days old) cells. However, significant flow of carbon through the photosynthetic intermediates resulting in the accumulation of sugars occurred in the late log-phase (34 days old) cells. Limitation of exogenous sugar in the nutrient milieu and depletion of reserve carbohydrates stored in starch of the chloroplasts of the cells were considered as the decisive factors in promoting transport of C(3) cycle intermediates through the reductive pentose phosphate pathway in photoheterotrophic cells. The observed drain of radioactivity even from the small amounts of tricarboxylic acid cycle intermediates synthesized during photosynthesis into glutamate indicated that the transport of carbon through the nonautotrophic pathway is not controlled by these factors.

20.
Plant Physiol ; 68(6): 1485-7, 1981 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16662131

RESUMO

The light saturated rate of photosystem I-dependent electron transport (ascorbate/dichlorophenol-indophenol --> methyl vilogen in presence of 1 micromolar 3-[3,4-dichlorophenyl]-1,1-dimethyl urea [DCMU]) was increased by a high concentration of DCMU added to broken and uncoupled chloroplasts isolated from pea (Pisum sativum). At 50 micromolar DCMU, the increase was around 50%. No stimulation was observed under limiting intensity of illumination, indicating that the relative quantum yield of electron transport was not affected by high DCMU. The light-saturated rate in coupled (to proton gradient formation) chloroplasts was unchanged by 50 micromolar DCMU, suggesting that the rate-limitation imposed by energy coupling was not affected. Using N,N,N',N'-tetramethyl-p-phenylene diamine as electron donor, essentially no DCMU stimulation of the rate was observed, indicating further that the electron donation at a site close to P700 was not affected by high DCMU. It is concluded that DCMU, in the range of 10 to 50 micromolar, affected the thylakoid membranes in such a way that the rate constant of electron donation by dichlorophenol-indophenol at the site prior to the site of energy coupling increased. Further observations that DCMU at 100 micromolar stimulated the rate in coupled chloroplasts indicated an additional DCMU action, presumably by uncoupling the chloroplasts from phosphorylation, as suggested by Izawa (Shibata et al., eds, Comprehensive Biochemistry and Biophysics of Photosynthesis, University Press, State College, Pennsylvania, pp 140-147, 1968). A scheme has been proposed for multiple sites of DCMU action on the electron transport system in chloroplasts.

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