RESUMO
The aim of the present study was to investigate EMG contamination on high-frequency scalp electroencephalogram (EEG) during comparisons of certain cognitive tasks performance. 19 healthy women who performed similar test tasks before and after cosmetic injections of Dysport in various face regions for reduction of facial muscles activity took part in the study. The test tasks were focused on induction of emotional states with different valences, on memory storing and extraction of verbal information. Default state of rest was uncluded too. During performance of the tasks, parallel registrations of EEG from a scalp surface(19 channels) and EMG from several facial muscles (6 channels) were carried out. Changes of spectral power in ß2 and low γ frequency ranges (18-40 Hz) in EEG- and EMG-derivations after Dysport injections were analyzed. Changes of spectral power in the same derivations during comparisons of the different test tasks were analyzed before and after Dysport injections separately. It was demonstrated that Dysport injections lead to reduction of EMG power in regions of injections and to reduction of EEG power in frontal and temporal derivations. However, the EEG-correlates revealed when comparing different test tasks remain qualitatively invariable both after, and before Disports injections. These facts confirmed that EMG makes a noticeable contribution to the electric activity registered from a scalp in the frequency ranges more than 18-Hz. At the same time, it was shown that in certain experimental situations influence of EMG not necessarily interferes with identification of EEG-correlates of mental activity during EEG registration from a head surface in ß2 and low γ frequency ranges.
Assuntos
Eletroencefalografia , Eletromiografia , Emoções , Músculos Faciais , Toxinas Botulínicas Tipo A , Músculos Faciais/fisiopatologia , Feminino , Humanos , Memória , Análise e Desempenho de TarefasRESUMO
BACKGROUND: A differentiated knowledge of trauma in children and adolescents is essential for the treatment of injured minors. The aim of this study was to present the focus of treatment in trauma emergency services. MATERIAL AND METHODS: Over a period of 2 years all acutely injured children and adolescents (n = 4784) in the emergency service were analyzed prospectively. The data were analyzed according to sex, age, date of examination, indications for x-ray imaging, diagnosis and therapy. RESULTS: Seasonal differences in the treatment spectrum were detected. In total 34.4 % of the patients presented with bruises/contusions, 23 % wounds, 19.9 % fractures, 14.9 % sprains/strains/ligament ruptures, 4.1 % craniocerebral trauma, 1.5 % dislocations, 1.1 % muscle/tendon injuries and 0.9 % burns. Of the patients 60 % underwent an x-ray examination and 8.3 % were hospitalized. Different injuries were found in the different age groups. Most fractures (25.7 %) were found at the distal forearm and most osteosyntheses (22.5 %) were also carried out at this anatomical location. CONCLUSION: Knowledge of the frequency and age dynamics is essential for competent treatment of injuries in children and adolescents. Analysis of the reality of the treatment in emergency services allows a much better evaluation of the requirements with respect to this clientele. The collected data can serve as a basis for the development of major capability foci, training concepts, treatment algorithms as well as prevention measures.
Assuntos
Serviço Hospitalar de Emergência/estatística & dados numéricos , Estações do Ano , Carga de Trabalho/estatística & dados numéricos , Ferimentos e Lesões/epidemiologia , Ferimentos e Lesões/terapia , Adolescente , Distribuição por Idade , Criança , Pré-Escolar , Alemanha/epidemiologia , Humanos , Lactente , Masculino , Prevalência , Fatores de Risco , Distribuição por Sexo , Revisão da Utilização de Recursos de Saúde , Ferimentos e Lesões/diagnósticoRESUMO
Lactoferrin (Ltf), an iron binding glycoprotein, is a pleiotropic molecule whose serum concentration increases under acute phase conditions. The physiological roles of this protein have been well elucidated, but the source and serum regulation of Ltf gene expression have not been investigated in detail as part of the acute phase reaction (APR). In the current work, the changes in hepatic Ltf-gene-expression during turpentine oil- (TO-) or LPS-induced APR were investigated. Ltf was upregulated at both the mRNA and protein levels in the liver of TO- and LPS-treated wild type (WT) mice. The pattern of induction however was different in both animal models indicating distinctive signalling patterns resulting in an acute phase reaction. Cytokines are the core regulators of APR. Among the major cytokines, IL-6 is an important signalling molecule, which also regulates iron homeostasis in response to an inflammatory situation. In this study, the administration of IL-6 induced Ltf gene expression in the liver of WT mice, in murine hepatocytes and in hepa 1-6 cells. Ltf-gene-expression was upregulated also in the liver of TO- and LPS-treated IL-6 knockout (KO) mice. The increase in serum Ltf after LPS injection was greater than after TO-injection both in WT and IL-6-KO mice. To evaluate the contribution of other acute phase cytokines in the regulation of Ltf-gene-expression in the liver, both in vitro and in vivo studies with IL-1ß, TNF-α, or IFN-γ were performed. The results demonstrate that TNF-α and IFN-γ also upregulated Ltf-gene-expression, while IL-1ß has no role in the regulation of Ltf-gene-expression.
Assuntos
Reação de Fase Aguda/genética , Lactoferrina/genética , Animais , Expressão Gênica , Hepatócitos/metabolismo , Interleucina-1beta/metabolismo , Interleucina-1beta/farmacologia , Interleucina-6/metabolismo , Interleucina-6/farmacologia , Lactoferrina/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos , Camundongos Knockout , RNA Mensageiro/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Regulação para CimaRESUMO
Liver regeneration may take place after liver injury through replication of hepatocytes or hepatic progenitor cells called oval cells. Interferons (IFN) are natural cytokines with pleiotrophic effects including antiviral and antiproliferative actions. No data are yet available on the physiology and cellular source of natural IFNs during liver regeneration. To address this issue, we have analyzed the levels and biologic activities of IFN-α/IFN-γ in two models of partial hepatectomy. After 2/3rd partial hepatectomy (PH), hepatic levels of IFN-α and IFN-γ declined transiently in contrast to a transient increase of the IFN-γ serum level. After administration of 2-acetylaminofluorene and partial hepatectomy (AAF/PH model), however, both IFN-α and IFN-γ expression were up-regulated in regenerating livers. Again, the IFN-γ serum level was transiently increased. Whereas hepatic IFN-γ was up-regulated early (day 1-5), but not significantly, in the AAF/PH model, IFN-α was significantly up-regulated at later time points in parallel to the peak of oval cell proliferation (days 7-9). Biological activity of IFN-α was shown by activation of IFN-α-specific signal transduction and induction of IFN-α specific-gene expression. We found a significant infiltration of the liver with inflammatory monocyte-like mononuclear phagocytes (MNP) concomitant to the frequency of oval cells. We localized IFN-α production only in MNPs, but not in oval cells. These events were not observed in normal liver regeneration after standard PH. We conclude that IFN-γ functions as an acute-phase cytokine in both models of liver regeneration and may constitute a systemic component of liver regeneration. IFN-α was increased only in the AAF/PH model, and was associated with proliferation of oval cells. However, oval cells seem not to be the source of IFN-α. Instead, inflammatory MNP infiltrating AAF/PH-treated livers produce IFN-α. These inflammatory MNPs may be involved in the regulation of the oval cell compartment through local expression of cytokines, including IFN-α.
Assuntos
Interferon-alfa/metabolismo , Interferon gama/metabolismo , Regeneração Hepática/fisiologia , Células-Tronco/metabolismo , 2-Acetilaminofluoreno/administração & dosagem , Animais , Proliferação de Células , Células Cultivadas , Hepatectomia , Hepatócitos/metabolismo , Janus Quinase 1/metabolismo , Células Matadoras Naturais/metabolismo , Masculino , Monócitos/metabolismo , RNA Mensageiro , Ratos , Ratos Wistar , Fatores de Transcrição STAT/metabolismoRESUMO
Important points on methodology and detailed description of methods used in polymodal psychophysiological studies of human verbal creative thinking are presented. The psychophysiological studies were conducted with healthy volunteers during implementations of specially developed and adapted psychological tests aimed to bring the subjects into states of verbal creative thinking. Four different task sets ("story composition", "associative chains", "original definitions", "proverb sense flipping") were developed and applied. Positron emission tomography of regional cerebral blood flow (rCBF) and state-related quantitative electroencephalography (power and coherence evaluated) were used. The effectiveness of the methods is illustrated with figures.
Assuntos
Criatividade , Psicofisiologia/métodos , Adolescente , Adulto , Encéfalo/diagnóstico por imagem , Circulação Cerebrovascular , Ciência Cognitiva/métodos , Eletroencefalografia , Feminino , Humanos , Masculino , Neurociências/métodos , Tomografia por Emissão de Pósitrons , Comportamento VerbalRESUMO
In this work, we used two rat models, partial hepatectomy (PH) and CCl(4) administration, to study the changes in iron pathways in response to hepatic damage. Liver injury induced changes in the hepatic gene expression of hepcidin, hemojuvelin (Hjv), several other proteins of iron metabolism, and several cytokines such as IL-1beta, IL-6, TNF-alpha, and IFN-gamma. Hepcidin gene expression was upregulated between 4 and 8 h with a maximum up to 16 h after surgery. However, Hjv gene expression was downregulated at the same time. An early upregulation of hepcidin (3 h) and downregulation of Hjv gene expression was found after CCl(4) administration. Transferrin receptor 1 and ferritin H gene expression was upregulated, whereas ferroportin 1 gene expression was downregulated. Hepatic IL-6 gene expression was upregulated early after PH and reached maximum 8 h after the PH. In CCl(4)-induced liver injury, IL-6, IL-1beta, TNF-alpha, and IFN-gamma upregulation were found at the maximum 12 h after the administration of the toxin. Treatment of isolated rat hepatocytes with IL-6 and, to a lesser extent, with IL-1beta but not with TNF-alpha or IFN-gamma dose dependently upregulated hepcidin and downregulated Hjv gene expression. In hepatic damage, changes of the hepatic gene expression of the main proteins involved in iron metabolism may be induced by locally synthesized mediators.
Assuntos
Hepatócitos/metabolismo , Interleucina-6/metabolismo , Ferro/metabolismo , Cirrose Hepática Experimental/metabolismo , Fígado/lesões , Fígado/metabolismo , Proteínas de Membrana/metabolismo , Animais , Células Cultivadas , Proteínas Ligadas por GPI , Expressão Gênica , Proteína da Hemocromatose , Hepatectomia , Cirrose Hepática Experimental/induzido quimicamente , Masculino , Ratos , Ratos WistarRESUMO
Historical background of error detection (ED) studies is restored here from the first suggestion of such a mechanism published (Rabbit, 1966) and the first related anatomo-physiological correlates observed [Bechtereva, N.P., Gretchin, V.B., 1968. Physiological foundations of mental activity. Int. Rev. Neurobiol., vol. 11. Academic Press, N.Y., pp. 239-246; Bechtereva, N.P., 1971. Neurophysiological Aspects of Human Mental Activity. Meditzina, Moskow. 120 pp., (in Russian); Bechtereva, N.P., 1974. Neurophysiological Aspects of Human Mental Activity, second edition, revied and complete Meditzina, Moskow. 151 pp., (in Russian)]. Data from evoked potentials together with new opportunities offered by the technological revolution of the 1980s-1990s provided a large body of knowledge on the ED. The overwhelming majority of the papers stress the spatial relation of ED to Anterior Cingulate Cortex. ED was revealed in a number of other zones to whose role should be specially discussed. The other point of interest is the late appearance of ED after the brain signs of correction which seems particularly important considering the supposed functional role of ED. Data of direct observations of ECoG dynamics in left and right human ACC on correct and erroneous test performance are presented. Research on ED resulted in the development of new ways in treatment of the obsessive-compulsive syndrome. Further psychophysiological research into the ED phenomena is considered as one of the priorities of fundamental and applied investigations for the elucidation of human brain functions. Opinion that ED plays an extremely important role in mechanisms of cognition and creativity is further argumented. Investigations in the field can contribute a lot to clinical neurophysiology as well.
Assuntos
Encéfalo/fisiologia , Neurologia/tendências , Desempenho Psicomotor/fisiologia , Eletrodos Implantados , HumanosRESUMO
Under certain conditions liver regeneration can be accomplished by hepatic progenitor cells ("oval cells"). So far, only few factors have been identified to be uniquely regulated by the "oval cell" compartment. Using macroarray analysis in a rat model of oval cell proliferation (treatment with 2-acetylaminofluorene and partial hepatectomy, AAF + PH), we identified 12 differentially expressed genes compared to appropriate control models (AAF treatment and sham operation or AAF treatment alone). Further analysis in models of normal liver regeneration (ordinary PH) and acute phase response (turpentine oil-treated rats) revealed that three out of 12 genes (thymidine kinase 1, Jun-D and ADP-ribosylation factor 4) were not affected by the hepatic acute phase reaction but similarly overexpressed in both "oval cell"-dependant and normal liver regeneration. We characterized Jun-D and ADP-ribosylation factors as novel factors upregulated in oval cells and in non-parenchymal liver cells of normally regenerating livers. However, two out of 12 differentially expressed genes were specifically expressed in oval cells: ras-related protein Rab-3b and Ear-2. On protein level, Rab-3b was increased in total liver homogenates and demonstrated only in clusters of oval cells. We postulate that Ear-2 and Rab-3b may represent novel regulatory factors specifically activated in "oval cells".
Assuntos
Hepatócitos/citologia , Regeneração Hepática/fisiologia , Células-Tronco/citologia , 2-Acetilaminofluoreno , Reação de Fase Aguda/induzido quimicamente , Reação de Fase Aguda/metabolismo , Animais , Proliferação de Células , Perfilação da Expressão Gênica , Hepatectomia , Hepatócitos/metabolismo , Fígado/citologia , Fígado/metabolismo , Fígado/fisiologia , Análise de Sequência com Séries de Oligonucleotídeos , Ratos , Ratos Wistar , Receptores de Esteroides/metabolismo , Células-Tronco/metabolismo , Fatores de Transcrição/metabolismo , Terebintina , Proteínas rab3 de Ligação ao GTP/metabolismoRESUMO
BACKGROUND/AIMS: Mx proteins are supposed to be strictly regulated by viruses or interferon-alpha (IFN-alpha). We used a non-viral model of acute liver injury to study Mx expression. METHODS: We induced toxic liver injury by CCl(4), and studied the expression of IFN-alpha, IFN-gamma, and IFN-inducible antiviral genes (Mx-2; 2'-5' oligoadenylate synthetase, 2-5 A; double-stranded RNA-activated protein kinase, PKR). RESULTS: Similar to 2-5 A and PKR, Mx-2 gene expression was biphasically induced after CCl(4) administration with a maximum at 24 h, and a second peak at 72 h. On protein level, Mx-2 only was up-regulated. IFN-alpha remained constant for the first 24 h while IFN-gamma peaked at 6 h. Thereafter, IFN-alpha increased to a maximum at 72 h while IFN-gamma decreased to 77+/-4%. Small monocyte-like liver macrophages, but not large macrophages, expressed Mx-2 constitutively. In vitro, IFN-alpha but not IFN-gamma induced Mx-2 in different liver cell populations. IFN-gamma, instead, reduced the susceptibility of liver macrophages to the actions of IFN-alpha. CONCLUSIONS: Our data suggest that Mx expression does not invariably result from the presence of a viral particle or IFN-alpha synthesis but may represent an innate defensive armamentarium that may be up-regulated without antigen specificity upon liver injury.
Assuntos
Intoxicação por Tetracloreto de Carbono/complicações , Proteínas de Ligação ao GTP/biossíntese , Hepatopatias/metabolismo , Hepatopatias/patologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Animais , Separação Celular , Doença Hepática Induzida por Substâncias e Drogas , Proteínas de Ligação ao GTP/genética , Proteínas de Ligação ao GTP/metabolismo , Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatócitos/patologia , Interferon-alfa/metabolismo , Interferon-alfa/farmacologia , Interferon gama/metabolismo , Interferon gama/farmacologia , Interferons/genética , Interferons/metabolismo , Fígado/patologia , Fígado/fisiopatologia , Hepatopatias/genética , Masculino , Proteínas de Resistência a Myxovirus , Fagócitos/patologia , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , eIF-2 Quinase/metabolismoRESUMO
In order to characterize the domain organization of sarcoplasmic reticulum Ca(2+)-ATPase in different physiological states, limited proteolysis using three proteases (proteinase K (prtK), V8 and trypsin) was conducted systematically and quantitatively. The differences between E(2) and E(2)P were examined in our previous study and E(2)P was characterized by the complete resistance to all three proteases (except for trypsin attack at the very top of the molecule (T1 site)). The same strategies were employed in this study for E(1)ATP, E(1)PADP and E(1)P states. Because of the transient nature of these states, they were either stabilized by non-hydrolyzable analogues or made predominant by adjusting buffer conditions. Aluminum fluoride (without ADP) was found to stabilize E(1)P. All these states were characterized by strong (E(1)ATP) to complete (E(1)PADP and E(1)P) resistance to prtK and to V8 but only weak resistance to trypsin at the T2 site. Because prtK and V8 primarily attack the loops connecting the A domain to the transmembrane helices whereas the trypsin T2 site (Arg(198)) is located on the outermost loop in the A domain, these results lead us to propose that the A domain undergoes a large amount of rotation between E(1)P and E(2)P. Combined with previous results, we demonstrated that four states can be clearly distinguished by the susceptibility to three proteases, which will be very useful for establishing the conditions for structural studies.
Assuntos
ATPases Transportadoras de Cálcio/metabolismo , Retículo Sarcoplasmático/enzimologia , Monofosfato de Adenosina/análogos & derivados , Monofosfato de Adenosina/farmacologia , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/metabolismo , Trifosfato de Adenosina/farmacologia , Compostos de Alumínio/farmacologia , Animais , ATPases Transportadoras de Cálcio/química , ATPases Transportadoras de Cálcio/efeitos dos fármacos , Citoplasma , Endopeptidases/metabolismo , Endopeptidases/farmacologia , Fluoretos/farmacologia , Magnésio/metabolismo , Magnésio/farmacologia , Nucleotídeos/metabolismo , Nucleotídeos/farmacologia , Estrutura Terciária de Proteína , CoelhosRESUMO
Sarcoplasmic reticulum Ca(2+)-ATPase was digested with proteinase K, V8 protease and trypsin in the absence of Ca(2+). Unphosphorylated enzyme was rapidly degraded. In contrast, ADP-insensitive phosphoenzyme formed with P(i) and phosphorylated state analogues produced by the binding of F(-) or orthovanadate, were almost completely resistant to the proteolysis except for tryptic cleavage at the T1 site (Arg(505)). The results indicate that the phosphoenzyme and its analogues have a very compact form in the cytoplasmic region, being consistent with large domain motions (gathering of three cytoplasmic domains). Results further show that the structure of the enzyme with bound decavanadate is very similar to ADP-insensitive phosphoenzyme. Thapsigargin did not affect the changes in digestion time course induced by the formation of the phosphorylated state analogues.
Assuntos
ATPases Transportadoras de Cálcio/metabolismo , Fosfoproteínas/metabolismo , Retículo Sarcoplasmático/enzimologia , Serina Endopeptidases/metabolismo , Difosfato de Adenosina/fisiologia , Animais , Sítios de Ligação , Cálcio/farmacologia , ATPases Transportadoras de Cálcio/química , ATPases Transportadoras de Cálcio/efeitos dos fármacos , Endopeptidase K/metabolismo , Fluoretos/metabolismo , Fluoretos/farmacologia , Concentração de Íons de Hidrogênio , Magnésio/metabolismo , Magnésio/farmacologia , Fosfoproteínas/química , Fosforilação , Ligação Proteica , Conformação Proteica , Coelhos , Tripsina/metabolismo , Vanadatos/farmacologiaAssuntos
Lipase/química , Lipase/metabolismo , Conformação Proteica , Pseudomonas/enzimologia , Substituição de Aminoácidos , Clonagem Molecular/métodos , Cristalografia por Raios X , Escherichia coli , Cinética , Lipase/biossíntese , Modelos Moleculares , Modelos Estruturais , Mutagênese Sítio-Dirigida , Engenharia de Proteínas/métodos , Dobramento de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , TermodinâmicaAssuntos
Clorofluorcarbonetos de Metano/economia , Redução de Custos/métodos , Serviço Hospitalar de Engenharia e Manutenção/economia , Refrigeração/economia , Conservação de Recursos Energéticos/economia , Tomada de Decisões , Controle de Formulários e Registros , Serviço Hospitalar de Engenharia e Manutenção/legislação & jurisprudência , Serviço Hospitalar de Engenharia e Manutenção/organização & administração , Serviço Hospitalar de Compras/organização & administração , Refrigeração/instrumentação , Refrigeração/normas , Estados Unidos , United States Environmental Protection AgencyRESUMO
The authors propose a method of complex treatment of patients with bronchial asthma and chronic obstructive bronchitis using a highly disperse ionizing sodium chloride aerosol. It proved more effective in comparison with traditional methods of treatment. Availability and simplicity of this method make it possible to use it widely in out- and inpatient conditions.
Assuntos
Asma/terapia , Bronquite/terapia , Cloreto de Sódio/administração & dosagem , Adolescente , Adulto , Aerossóis , Asma/fisiopatologia , Bronquite/fisiopatologia , Doença Crônica , Terapia Combinada , Seguimentos , Humanos , Pessoa de Meia-Idade , Tamanho da Partícula , Respiração/fisiologiaRESUMO
The effect of Boc-DPhe-Phe-Lysinal (Boc-DPPL) on the 45Ca2+ uptake of rat anterior pituitary monolayer cultures was investigated. The compound decreased the basal Ca2+ uptake at 3 x 10(-4) mol/l. The 45Ca2+ uptake stimulated by potassium-induced depolarization was more sensitive to Boc-DPPL inhibition, a slight decrease was seen with 3 x 10(-6) mol/l and there was a half maximal inhibition at 3 x 10(-5) mol/l. Boc-DPPL is known to inhibit pituitary hormone release in similar concentrations, an effect might also be due to its calcium antagonist property.
Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Oligopeptídeos/farmacologia , Hipófise/metabolismo , Animais , Cálcio/metabolismo , Radioisótopos de Cálcio , Células Cultivadas , Masculino , Hipófise/citologia , Hipófise/efeitos dos fármacos , RatosRESUMO
Phosphorylation of polypeptides in isolated thylakoids was examined during chloroplast biogenesis in greening etiolated wheat leaves and 4 day-old wheat leaves grown under a diurnal light regime. At early stages of plastid development standard thylakoid preparations were heavily contaminated with nuclear proteins, which distorted the polypeptide phosphorylation profiles. Removal of contamination from membranes by sucrose density centrifugation demonstrated that the major membrane phosphoprotein in etioplasts was at 35 kDa. During etioplast greening a number of phosphoproteins appeared, of which the 25-27 kDa apoproteins of the light-harvesting chlorophylla/b protein complex associated with photosystem II (LHCII) became the most dominant. At the early stages of thylakoid development found at the base of the 4-day-old light grown leaf the LHCII apoproteins were evident as phosphoproteins; however the major phosphoprotein was polypeptide atca. 9kDA. Phosphorylation of both the LHCII apoproteins and the 9 kDa polypeptide in these thylakoids was not light-dependent. In the older thylakoids isolated from the leaf tip the LHCII apoproteins were the major phosphoproteins and their phosphorylation had become light-regulated; however phosphorylation of the 9 kDa polypeptide remained insensitive to light.
RESUMO
The ch4 mutant of sweetclover (Melilotus alba) has previously been demonstrated to be partially deficient in chlorophyll and to have a higher ratio of chlorophyll a to b than normal plants. We were able to substantiate these findings when plants were grown at 23 degrees C and lower (permissive temperatures). However, when grown at 26 degrees C (nonpermissive temperature) the plants produced small yellow leaves which exhibited one-twentieth the chlorophyll content of normal plants. Affected leaves did not increase their chlorophyll content when plants were incubated at permissive temperatures, but leaves which developed at the lower temperature contained increased amounts of chlorophyll. Similarly, only new leaves, not previously grown leaves, exhibited the yellow phenotype when the mutant plant was shifted from the permissive temperature to the nonpermissive temperature. Ribulose 1,5-bisphosphate carboxylase activity was decreased by half, relative to normal plants, in the mutant plants grown at the nonpermissive temperature, indicating that general protein synthesis was not greatly impaired and that the effect of the mutation was perhaps specific for chlorophyll content. HPLC analysis indicated that carotenoid content was not diminished to the same extent as chlorophyll and we have determined that the thylakoid protein kinase is not altered, as is the case for other chlorophyll b-deficient mutants. Experiments suggest that changes in photoperiod may be able to modulate the effect of temperature.
RESUMO
Sarcoplasmic reticulum isolated from rabbit skeletal muscle was labeled with a limited (0.625 nmol/mg sarcoplasmic reticulum protein) amount of the fluorescent thiol reagent N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide (DACM). The fluorescence intensity of the membrane-attached DACM decreased concurrently with (Ca2+ and caffeine)-induced Ca2+ release, depolarization-induced Ca2+ release and Ca2+-dependent dependent passive efflux of Ca2+. The decreased DACM fluorescence level initiated by a Ca2+ jump was subsequently reversed under passive efflux conditions when there was no ATP-dependent Ca2+ uptake, suggesting spontaneous closing of the channels. Therefore, the higher fluorescence level corresponds to a larger population of closed channels, whereas the lower level represents a larger population of opened channels. Under conditions when the Ca2+ release-coupled fluorescence change was maximal, a stoichiometric incorporation of DACM took place only into a 32-kDa protein. Furthermore, reconstituted vesicles, in which purified DACM-labeled 32-kDa protein was incorporated into unlabeled sarcoplasmic reticulum vesicles, were capable of both (Ca2+ and caffeine)-induced Ca2+ release and the release-coupled DACM fluorescence change. These results suggest that the 32-kDa protein is a constituent of the Ca2+ release channel or a protein which is in close contact with the channel.
Assuntos
Cálcio/metabolismo , Canais Iônicos/metabolismo , Retículo Sarcoplasmático/metabolismo , Trifosfato de Adenosina/farmacologia , Animais , Cafeína/antagonistas & inibidores , Cafeína/farmacologia , Corantes Fluorescentes/metabolismo , Canais Iônicos/efeitos dos fármacos , Maleimidas/metabolismo , Microssomos/metabolismo , Proteínas Musculares/metabolismo , Conformação Proteica , Coelhos , Rutênio Vermelho/farmacologia , Retículo Sarcoplasmático/efeitos dos fármacos , Tetracaína/farmacologiaRESUMO
Protein kinase activity was detected in osmotically lysed mitochondria isolated from etiolated seedlings of corn, pea, soybean, and wheat, as well as from potato tubers. Ther kinase(s) phosphorylated both endogenous polypeptides and exogenous, nonmitochondrial proteins when supplied with ATP and Mg(2+). Eight to fifteen endogenous mitochondrial polypeptides were phosphorylated. The major mitochondrial polypeptide labeled in all species migrated during denaturing electrophoresis with an apparent monomeric molecular weight of 47,000. Incorporation of phosphate into endogenous proteins appeared to be biphasic, being most rapid during the first 1 to 2 minutes but slower thereafter. The kinase activity was greatest at neutral and alkaline pH values and utilized ATP with a K(m) of approximately 200 micromolar. The kinase was markedly inhibited by CaCl(2) but was essentially unaffected by NaF, calmodulin, oligomycin, or cAMP. These data suggest that plant mitochondrial protein phosphorylation may be similar to protein phosphorylation in animal mitochondria.
RESUMO
The effects of dantrolene, which is a known muscle relaxant, on Ca2+ release from the isolated sarcoplasmic reticulum induced by several different methods [1) addition of caffeine, (2) Ca2+ jump, and (3) membrane-depolarization produced by choline chloride replacement of potassium gluconate) were investigated. Dantrolene inhibited caffeine-induced Ca2+ release with C1/2 = 2.5 microM, whereas there was no effect on Ca2+ release induced by a Ca2+ jump. The amount of Ca2+ released by depolarization was reduced if Ca2+ release was triggered in an earlier phase of the steady state of Ca2+ uptake (time elapsed between the addition of ATP and the triggering of Ca2+ release, tATP less than 4 min); while, if triggered in a latter phase (tATP greater than 4 min) dantrolene enhanced depolarization-induced Ca2+ release. C1/2 for the inhibition and that for enhancement of depolarization-induced Ca2+ release were 1.0 and 0.3 microM, respectively. These results suggest that dantrolene affects several different steps of the mechanism by which Ca2+ release is triggered. The sarcoplasmic reticulum and T-tubule membrane fractions had 7.9 nmol dantrolene-binding sites/mg (Kassoc = 1.0 X 10(5) M-1) and 21.0 nmol/mg (Kassoc = 1.1 X 10(5) M-1), respectively. The time-course of dantrolene binding to sarcoplasmic reticulum was monophasic, while that to T-tubules was biphasic.