RESUMO
OBJECTIVE: To compare the complications and the difficulty of orotracheal intubation procedures performed in the Intensive Care Unit during the off-hours period and the on-hours period. DESIGN: A prospective, observational and non-interventional cohort study covering a period of 27 months was carried out. Working days between 8:00 a. m. and 7:59 p. m. were considered «on-hours¼, while the remaining shifts were regarded as «off-hours¼. SCOPE: An 18-bed surgical in a Intensive Care Unit of a third-level hospital. PATIENTS: All orotracheal intubation patients admitted to the ICU from January 2015 to March 2017 were included. Patients were stratified into 2groups according to whether intubation was performed on-hours or off-hours. INTERVENTIONS: Non-interventional study. VARIABLES OF INTEREST: The reason for intubation, time and day on which intubation was performed, degree of intubation difficulty (number of attempts, Cormack-Lehane laryngoscopic vision, need for accessory material) and complications during intubation. RESULTS: A total of 252 patients were intubated; of these, 132 were included in the on-hours group and 120 patients in the off-hours group. In the off-hours group we observed a greater percentage of urgent and emergent intubations compared to the on-hours group. However, no differences were found between the 2groups in relation to the other variables studied. CONCLUSIONS: During the off-hours period, orotracheal intubation was not associated to a greater number of complications or to greater difficulty of the technique in our Unit.
Assuntos
Plantão Médico , Hipotensão/etiologia , Hipóxia/etiologia , Unidades de Terapia Intensiva , Intubação Intratraqueal/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Manuseio das Vias Aéreas , Grupos Diagnósticos Relacionados , Feminino , Humanos , Hipotensão/epidemiologia , Hipóxia/epidemiologia , Unidades de Terapia Intensiva/organização & administração , Laringoscopia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Risco , Tamanho da Amostra , Centros de Atenção TerciáriaRESUMO
Alternating d(GA.TC)(n)DNA sequences, which are abundant in eukaryotic genomes, can form altered DNA structures. Depending on the environmental conditions, the formation of (GA.GA) hairpins or [C+T(GA.TC)] and [GA(GA.TC)] intramolecular triplexes was observed in vitro. In vivo, the formation of these non-B-DNA structures would likely require the contribution of specific stabilizing factors. Here, we show that Friend's nuclear extracts are rich in proteins which bind the pyrimidine d(TC)(n)strand but not the purine d(GA)n strand (NOGA proteins). Upon chromatographic fractionation, four major proteins were detected (NOGA1-4) that have been purified and characterized. Purified NOGAs bind single-stranded d(TC)n with high affinity and specificity, showing no significant affinity for either d(GA)n or d(GA.TC)nDNA sequences. We also show that NOGA1, -2 and -3, which constitute the three most abundant and specific NOGA proteins, correspond to the single-stranded nucleic acid binding proteins hnRNP-L, -K and -I, respectively. These results are discussed in the context of the possible contribution of the NOGA proteins to the stabilization of the (GA.GA) and [GA(GA.TC)] conformers of the d(GA.TC)n DNA sequences.
Assuntos
DNA/metabolismo , Proteínas Nucleares/metabolismo , Purinas/metabolismo , Pirimidinas/metabolismo , Sequência de Aminoácidos , Western Blotting , DNA/química , Dados de Sequência Molecular , Proteínas Nucleares/química , Ligação ProteicaRESUMO
Isothermal titration calorimetry (ITC) profiles of berenil bound to different DNAs show that, despite the strong preference of berenil for AT-rich regions in DNA, it can bind to other DNA sequences significantly. The ITC results were used to quantify the binding of berenil, and the thermodynamic profiles were obtained using natural DNAs as well as synthetic polynucleotides. ITC binding isotherms cannot be simply described when a single set of identical binding sites is considered, except for poly[d(A-T)2]. Ultraviolet melting of DNA and differential scanning calorimetry were also used to quantify several aspects of the binding of berenil to salmon testes DNA. We present evidence for secondary binding sites for berenil in DNA, corresponding to G+C rich sites. Berenil binding to poly[d(G-C)2] is also observed. Circular dichroism experiments showed that binding to GC-rich sites involves drug intercalation. Using a molecular modeling approach we demonstrate that intercalation of berenil into CpG steps is sterically feasible.
Assuntos
DNA/metabolismo , Diminazena/metabolismo , Animais , Varredura Diferencial de Calorimetria , Dicroísmo Circular , DNA/química , Diminazena/análogos & derivados , Diminazena/química , Modelos Moleculares , Estrutura Molecular , TermodinâmicaRESUMO
The centromeric dodeca-satellite of Drosophila forms unusual DNA structures in which its purine-rich strand (GTACGGGACCGA)n folds into very stable intramolecular hairpins. These intramolecular hairpins contain groups of tandem 5'-GA:GA-3' mismatches that, as judged by gel electrophoresis analysis and UV-melting studies, have a determinant contribution to their stability. Duplexes of the dodeca-satellite purine-rich strand, carrying tandem 5'-GA:GA-3' mismatches, are as stable as equivalent fully Watson-Crick duplexes containing tandem 5'-TA:TA-3' Watson-Crick pairs in place of the non-Watson-Crick G.A pairs. On the other hand, duplexes carrying any of the other three possible tandem combinations of purine.purine mismatches, including G.A pairs on the opposite orientation 5'-AG:AG-3', are very unstable. The high stability of the dodeca-satellite hairplus suggests that the tandem G.A pairs are on the sheared configuration although they are found within the less favourable 5'-G-(G-A)-C-3' sequence context. Other centromeres DNA sequences, including the AAGAG satellite of Drosophila and the mammalian CENP-B box sequence, have the potential of forming intramolecular hairpins stabilised by similar purine.purine interactions.
Assuntos
DNA Satélite/química , DNA Satélite/genética , Drosophila/genética , Animais , Composição de Bases , Sequência de Bases , Centrômero/genética , DNA Satélite/efeitos da radiação , Estabilidade de Medicamentos , Conformação de Ácido Nucleico/efeitos da radiação , Desnaturação de Ácido Nucleico/efeitos da radiação , Sequências Repetitivas de Ácido Nucleico , Raios UltravioletaRESUMO
Alternating d(GA.TC)n sequences are highly structurally polymorphic. Most of their conformational flexibility is likely to reside in the structural properties of the individual strands themselves. In this paper the conformational behaviour of the d(GA)20 and d(TC)20 oligonucleotides was analysed. Formation of d(GA)20 intramolecular duplexes is observed at any pH value, from 8.3 to 4.6. On the other hand, intramolecular d(TC)20 duplexes are formed only under acidic conditions. The acid d(TC)20 intramolecular duplex is likely to be stabilized through the formation of C+C pairs, the thymine residues remaining unpaired. The d(GA)20 oligonucleotide also forms intermolecular duplexes which coexist with the intramolecular forms at any pH, from 8.3 to 4.6. The structural conformation adopted by the d(TC)20 oligonucleotide at neutral pH is uncertain. Under these conditions, this oligonucleotide shows an electrophoretic apparent molecular weight consistent with the formation of a bimolecular complex. However, no hydrogen bonding was observed to occur under these conditions. Implications of these results for an understanding of the molecular principles behind the conformational flexibility of alternating d(GA.TC)n sequences are discussed. The possible biological significance of these results is also discussed.
Assuntos
Conformação de Ácido Nucleico , Polidesoxirribonucleotídeos/química , Polimorfismo Genético , Sequência de Bases , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Dados de Sequência MolecularRESUMO
SHP-1 is a key tyrosine phosphatase that acts as a negative regulator of signal transduction in lymphocytes, which has been found down-regulated in several T cell lines derived from human T cell malignancies. The standardization of a sensitive ELISA for the quantification of SHP-1 protein in peripheral T and B lymphocytes has enabled us to quantify the SHP-1 content of freshly isolated T cells from patients with Sezary syndrome and in the Sezary T cell line HUT-78. In all cases, a dramatic decrease in the content of this protein, when compared with the content in healthy volunteer controls, was observed. These results were corroborated when the expression of SHP-1 mRNA was analyzed. In order to study whether there was any correlation between SHP-1 protein expression and tyrosine phosphorylated state of JAK3, the state of phosphorylation of JAK3 was studied in the T cell line HUT-78, and found to be highly phosphorylated. These results suggest that SHP-1 might be involved in maintaining the IL-2R/JAK3 signaling pathway under control and point towards a role of SHP-1 in the pathogenesis of the disease.
Assuntos
Proteínas de Neoplasias/fisiologia , Células-Tronco Neoplásicas/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas Tirosina Fosfatases/fisiologia , Proteínas Tirosina Quinases/fisiologia , Síndrome de Sézary/metabolismo , Transdução de Sinais , Neoplasias Cutâneas/metabolismo , Linfócitos T/metabolismo , Indução Enzimática , Ensaio de Imunoadsorção Enzimática , Regulação Neoplásica da Expressão Gênica , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Janus Quinase 3 , Células Jurkat/metabolismo , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/química , Proteínas de Neoplasias/genética , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 6 , Proteínas Tirosina Fosfatases/biossíntese , Proteínas Tirosina Fosfatases/genética , Proteínas Tirosina Quinases/química , RNA Mensageiro/biossíntese , RNA Neoplásico/biossíntese , Receptores de Interleucina-2/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade , Síndrome de Sézary/patologia , Neoplasias Cutâneas/patologia , Transcrição Gênica , Células Tumorais CultivadasRESUMO
In the present study we described the effects of a new 1,4-dihydropyridine derivative with antithrombotic activity on phosphoinositide turnover in washed platelets stimulated by either platelet-activating factor or thrombin. In 32P-labeled rabbit platelets, both PAF and thrombin evoked a transient loss of [32P]phosphatidylinositol 4,5-bisphosphate (PIP2) and, thereafter, labeling increased over the control value. Concomitantly, a progressive formation of phosphatidic acid was observed. In [3H]arachidonate labeled platelets, both agonists elicited an increase in diacylglycerol (DAG) levels and arachidonate release. Pretreatment of platelets with the new dihydropyridine derivative (PCA-4230) prevents, in a dose-dependent fashion, the PAF-evoked variations in phosphoinositide turnover and DAG production. However, thrombin-induced variations were rather enhanced by PCA-4230. With respect to arachidonate release and platelet aggregation, the drug was again selective against PAF and thrombin. Although PCA-4230 shows some PAF antagonistic activity, its effects on PAF-evoked responses did not seem only due to an antagonism at receptor level. In view of the present results, the drug is not only able to discern the pathways of platelet activation by which PAF and thrombin exert their action, but it also affects selectively the enhanced phosphoinositide turnover and arachidonate release evoked by thrombin. Thereafter, PCA-4230 is a suitable tool to explore the mechanisms of action of the natural agonists.
Assuntos
Plaquetas/efeitos dos fármacos , Di-Hidropiridinas/farmacologia , Fator de Ativação de Plaquetas/antagonistas & inibidores , Trombina/antagonistas & inibidores , Animais , Ácido Araquidônico/isolamento & purificação , Plaquetas/metabolismo , Diglicerídeos/isolamento & purificação , Di-Hidropiridinas/química , Fosfatidilinositóis/isolamento & purificação , Fosfatidilinositóis/metabolismo , Fator de Ativação de Plaquetas/fisiologia , Agregação Plaquetária/efeitos dos fármacos , Coelhos , Trombina/fisiologia , Fosfolipases Tipo C/antagonistas & inibidoresRESUMO
The effect of a new PAF (platelet activating factor; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphoryl-choline) receptor antagonist, PCA-4248 (2-phenylthio)ethyl-5-metoxycarbonyl-2,4,6-trimethyl-1, 4-dihydropyridine-3-carboxylate), on phosphoinositide turnover evoked by PAF was investigated. PAF treatment resulted in an increased 32P incorporation into phosphoinositides and phosphatidic acid in rabbit platelets. Treatment with PCA-4248 abolished both effects in a dose-dependent manner, 10 microM being the most effective dose. In thrombin stimulated platelets, phosphoinositide turnover was not influenced by PCA-4248. In addition, PAF caused a rapid and significant increase in protein phosphorylation. Thus, PAF treatment resulted in a marked phosphorylation of two proteins of 47 kDa and 20 kDa. Treatment with PCA-4248 resulted in an inhibition of these actions. Serotonin secretion evoked by PAF was also inhibited by PCA-4248. It is concluded that PCA-4248 antagonizes the PAF effects by acting as a competitive antagonist at the PAF receptor level as evidenced from binding studies.
Assuntos
Plaquetas/metabolismo , Di-Hidropiridinas/farmacologia , Fosfatidilinositóis/metabolismo , Fator de Ativação de Plaquetas/antagonistas & inibidores , Glicoproteínas da Membrana de Plaquetas/antagonistas & inibidores , Receptores de Superfície Celular , Receptores Acoplados a Proteínas G , Animais , Plaquetas/efeitos dos fármacos , Membrana Celular/metabolismo , Técnicas In Vitro , Cinética , Radioisótopos de Fósforo , Fosforilação , Coelhos , Serotonina/sangueRESUMO
The effect of PCA-4230, a new dihydropyridine derivative with a potent antithrombotic activity, on cyclic nucleotide phosphodiesterase in platelets was studied. PCA-4230 inhibited (54%) cyclic GMP hydrolytic activity of a platelet cytosolic fraction, whereas it did not affect that of cyclic AMP. Results suggested that PCA-4230 inhibited a cyclic GMP-dependent phosphodiesterase, known as cGB PDE or type V, on a purified enzyme from rabbit platelets by a non-competitive-uncompetitive type inhibition. In addition, PCA-4230 potentiated the increase in both cyclic GMP and cyclic AMP levels evoked by sodium nitroprusside. Furthermore, PCA-4230 and forskolin caused a synergistic effect in cyclic AMP, and also potentiated the phosphorylation of 50 kDa and 22 kDa proteins, reported as substrates of cyclic GMP- and cyclic AMP-dependent protein kinases that are related to the inhibition of platelet functions. Finally, PCA-4230 also potentiated the forskolin- and sodium nitroprusside-inhibited serotonin release evoked by thrombin, probably related to the increased cyclic nucleotide level.
Assuntos
Plaquetas/enzimologia , GMP Cíclico/farmacologia , Di-Hidropiridinas/farmacologia , Fibrinolíticos/farmacologia , 1-Metil-3-Isobutilxantina/farmacologia , 3',5'-GMP Cíclico Fosfodiesterases/antagonistas & inibidores , Animais , Plaquetas/efeitos dos fármacos , Colforsina/farmacologia , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Sinergismo Farmacológico , Cinética , Nitroprussiato/farmacologia , Inibidores de Fosfodiesterase/farmacologia , Fosforilação/efeitos dos fármacos , Coelhos , Serotonina/metabolismo , Trombina/farmacologia , Vasodilatadores/farmacologiaRESUMO
We have studied the effects of PCA-4230, a new dihydropyridine derivative with antithrombotic activity, on the secretion of dense and alpha-granules from platelets and on the protein phosphorylation in platelets after stimulation by agonists. The drug prevented both dense and alpha-granule secretion evoked by thrombin, platelet-activating factor (PAF) and ionophore A23187, the former secretion being more sensitive than the latter one to the PCA-4230 action. These inhibitory effects on secretion processes did not correlate with the differential action of PCA-4230 on protein phosphorylation. Thus, the 40 kDa protein phosphorylation evoked by thrombin was potentiated whereas that elicited by ionophore A23187 was partially inhibited. The 20 kDa protein phosphorylation was practically insensitive to the drug action. These data, together with previous evidence reported by us on PCA-4230, lead us to suggest the existence of a common and critical step for platelet secretion evoked by agonists with different signal transduction pathways.
Assuntos
Plaquetas/efeitos dos fármacos , Proteínas Sanguíneas/efeitos dos fármacos , Grânulos Citoplasmáticos/efeitos dos fármacos , Di-Hidropiridinas/farmacologia , Fibrinolíticos/farmacologia , Animais , Proteínas Sanguíneas/metabolismo , Calcimicina/farmacologia , Fosforilação , Fator de Ativação de Plaquetas/farmacologia , Coelhos , Trombina/farmacologiaRESUMO
In the presence of specific metal-ions (namely zinc but also cadmium, cobalt and manganese), d(GA x TC)n DNA sequences can form non-B-DNA conformations. At low metal-ion concentration they form [GA(GA x TC)] intramolecular triplexes but, upon increasing the metal concentration, the formation of (GA x GA) intramolecular hairpins is detected. In this paper we address the question of the specific effects of zinc on the structure of the d(GA x TC)n sequences. In the presence of zinc, the DMS-reactivity of the (GA x GA) hairpins is strongly reduced suggesting a direct interaction of the metal-ion with the N7-group of the guanines. This effect is specific for antiparallel-stranded d(GA)n homoduplexes. No such strong decrease in DMS-reactivity is observed in B-DNA duplexes or in d(GGA)n and d(GGGA)n homoduplexes. In addition, the thermal stability of antiparallel-stranded d(GA)n homoduplexes increases in the presence of zinc. On the contrary, the melting temperature of similar B-DNA molecules decreases upon increasing the zinc concentration. Altogether, these result indicate that zinc plays an specific role on the stabilization of the (GA x GA) intramolecular hairpins.
Assuntos
DNA/metabolismo , Polidesoxirribonucleotídeos/metabolismo , Zinco/metabolismo , Cátions Bivalentes , DNA/química , Metilação de DNA , Íons , Conformação de Ácido Nucleico , Polidesoxirribonucleotídeos/química , Ésteres do Ácido Sulfúrico/metabolismoRESUMO
PURPOSE/METHOD: We studied a patient whose embolic retinal occlusion originated in a free floating thrombus detached from an atheromatous plaque sited in the aortic arch. RESULTS/CONCLUSIONS: Atheroma in the ascending aorta artery and its arch can be a potential source of emboli in patients suffering of retinal embolism. Atherosclerotic lesions in thoracic aorta may be shedding free floating detachments on to the lumen of the artery with severe risk of peripheral embolism. These lesions can be detected by trans-esophageal echocardiography in thoracic areas of the aorta and may become an option when thrombus sources in cardiac ot carotid artery are not clearly identified.
Assuntos
Doenças da Aorta/complicações , Embolia de Colesterol/complicações , Embolia/etiologia , Doenças Retinianas/etiologia , Idoso , Aorta Torácica , Humanos , MasculinoRESUMO
OBJETIVO: Comparar las complicaciones y el grado de dificultad de la intubación orotraqueal realizada en una Unidad de Cuidados Críticos, durante el periodo off-hours (turno de noche y fines de semana) y el periodo on-hours (turno de día). DISEÑO: Estudio de cohortes, prospectivo, observacional y no intervencionista, durante un periodo de 27 meses. Se consideró on-hours el periodo de entre las 8:00 a. m. y las 7:59 p. m. de los días laborales, y off-hours el resto de los turnos. Ámbito: Una Unidad de Cuidados Críticos de 18 camas de un hospital clínico universitario de tercer nivel. PACIENTES: Se incluyó a todos los pacientes con intubación orotraqueal en la unidad desde enero de 2015 hasta marzo de 2017. Los pacientes se estratificaron en 2 grupos en función de si la intubación se realizaba en periodo on-hours u off-hours. INTERVENCIONES: Estudio no intervencionista. Variables de interés: Motivo de intubación, hora y día en el que se realiza la intubación, grado de dificultad de intubación (número de intentos, visión laringoscópica Cormack-Lehane, necesidad de material complementario) y complicaciones durante la intubación. RESULTADOS: Se intubó a 252 pacientes, de los que 132 fueron incluidos en el grupo on-hours y 120 en el grupo off-hours. En el grupo off-hours observamos un mayor porcentaje de intubaciones urgentes o emergentes en comparación con el grupo on-hours. No encontramos diferencias entre los 2grupos en el resto de las variables estudiadas. CONCLUSIONES: La intubación que se realiza en nuestra unidad durante el periodo off-hours no se ha podido asociar a un mayor número de complicaciones ni a una mayor dificultad de la técnica
OBJECTIVE: To compare the complications and the difficulty of orotracheal intubation procedures performed in the Intensive Care Unit during the off-hours period and the on-hours period. DESIGN: A prospective, observational and non-interventional cohort study covering a period of 27 months was carried out. Working days between 8:00 a. m. and 7:59 p. m. were considered «on-hours», while the remaining shifts were regarded as «off-hours». Scope: An 18-bed surgical in a Intensive Care Unit of a third-level hospital. PATIENTS: All orotracheal intubation patients admitted to the ICU from January 2015 to March 2017 were included. Patients were stratified into 2groups according to whether intubation was performed on-hours or off-hours. INTERVENTIONS: Non-interventional study. Variables of interest: The reason for intubation, time and day on which intubation was performed, degree of intubation difficulty (number of attempts, Cormack-Lehane laryngoscopic vision, need for accessory material) and complications during intubation. RESULTS: A total of 252 patients were intubated; of these, 132 were included in the on-hours group and 120 patients in the off-hours group. In the off-hours group we observed a greater percentage of urgent and emergent intubations compared to the on-hours group. However, no differences were found between the 2groups in relation to the other variables studied. CONCLUSIONS: During the off-hours period, orotracheal intubation was not associated to a greater number of complications or to greater difficulty of the technique in our Unit
Assuntos
Humanos , Intubação Intratraqueal/métodos , Unidades de Terapia Intensiva/estatística & dados numéricos , Laringoscopia/métodos , Intubação Intratraqueal/estatística & dados numéricos , Estudos Prospectivos , Estudos de Coortes , Hipotensão/complicações , Jornada de Trabalho em Turnos , 28599RESUMO
Intestinal intraepithelial lymphocytes (i-IEL) represent one of the largest, non-organized lymphoid population in the body. They are located outside the epithelial basement membrane among the mucosal epithelial cells. We, and previously other groups, have reported the presence of a CD7+CD3-IEL subset in the epithelium of human small intestine. This subset is drastically reduced in coeliac disease (CD) patients. In the present work we accomplish a better phenotypic characterization of this CD3-IEL subset and demonstrate the expression of typical natural killer (NK) cell markers. Most, if not all, CD3-CD7+ cells express NKPR1 (CD161)[98% +/- 2] and CD122[92% +/- 6]. In addition, a variable percentage express CD2[55% +/- 16], CD94[24% +/- 18], CD56[44% +/- 21] and CD16[12% +/- 4], however, no CD57 expression was observed. Moreover, these cells contain perforin granules[75% +/- 5], supporting a potential cytolytic ability. Regarding adhesion molecules, CD18 and CD44 expression is absent, which is consistent with a limited capacity of migration. Altogether, these data suggest the presence of intraepithelial NK cells in human intestinal epithelium, a compartment where cytotoxic effectors have not been clearly defined.
Assuntos
Antígenos CD7/análise , Complexo CD3/análise , Moléculas de Adesão Celular/análise , Mucosa Intestinal/imunologia , Células Matadoras Naturais/imunologia , Subpopulações de Linfócitos T/imunologia , Antígenos CD18/análise , Criança , Humanos , Receptores de Hialuronatos/análise , LactenteRESUMO
The action of platelet-activating factor (PAF) on phosphoinositide hydrolysis was studied in rat brain slices. PAF produced a significant increase of 32P incorporation into phosphoinositides and phosphatidic acid (PA), in a dose- and time-dependent manner. Concomitantly, an increase of inositol phosphates and diacylglycerol (DAG) production was observed. Both inositol bisphosphate (IP2) and inositol trisphosphate (IP3) were detected as early as 5 s and they returned immediately to basal levels; concomitantly, formation of inositol monophosphate (IP) was detected. These findings demonstrated that PAF causes a rapid hydrolysis of polyphosphoinositides in cerebral cortex by a phospholipase C-dependent mechanism followed by subsequent resynthesis.
Assuntos
Córtex Cerebral/enzimologia , Fosfatidilinositóis/metabolismo , Fator de Ativação de Plaquetas/farmacologia , Fosfolipases Tipo C/metabolismo , Animais , Diglicerídeos/metabolismo , Relação Dose-Resposta a Droga , Ativação Enzimática , Técnicas In Vitro , Fosfatos de Fosfatidilinositol , Ratos , Fosfolipases Tipo C/efeitos dos fármacosRESUMO
The existence of cross-talk mechanisms between the cyclic nucleotide system and other transduction systems involved in PAF-activated platelets is described in this study. A protein of 125 kDa, identified as pp 125(FAK), is tyrosine phosphorylated by PAF in a time- and concentration-dependent manner. The presence of a cAMP- or a cGMP-elevating agent, used alone or in combination, together with PAF diminished tyrosine phosphorylation. The sensitivity to cAMP shown by PAF-induced ppl25 phosphorylation on tyrosine residues was similar to PAF-induced phosphorylation of a 47-kDa protein (pp47) on serine and threonine. In contrast, the latter was not affected in the presence of a cGMP-elevating agent, although it was able to enhance synergistically the inhibitory effect of forskolin. Data reported herein also show that pp47 phosphorylation and serotonin secretion are not closely correlated. Accordingly, sodium nitroprusside (SNP) did not have any effect on phosphorylation of pp47, but it was able to inhibit serotonin secretion when added alone, and it showed a synergistic inhibitory action with forskolin.
RESUMO
The effect of lauryl gallate (antioxidant E-312) has been studied on the mouse B-cell lymphoma line Wehi 231. This compound is able to inhibit protein tyrosine kinases (PTKs) in whole cells and in crude extracts with a better efficiency than other well-known PTK inhibitors such as herbimycin or genistein. Initial events triggered upon the incubation of cells with lauryl gallate in phosphate-buffered saline (up to 1 h) include the inhibition of tyrosine phosphorylation, discharge of the mitochondrial transmembrane potential, and induction of mRNA for Bcl-2. Long-term cultures in complete medium supplemented with fetal calf serum (up to 24 h) in the presence of this compound exhibit clear apoptotic features such as increase in phosphatidylserine in the cell surface, decrease in the functionality of mitochondria, cytochrome c release to the cytosol, activation of caspases, hypodiploidy, and oligonucleosomal breakdown of DNA. Comparison between Wehi cells overexpressing Bcl-2 (Wehi-bcl-2) with Wehi-neo cells shows a delay in the manifestations of the apoptotic signs, indicating that Bcl-2 has a partial protective effect on the apoptosis induced by lauryl gallate. The proapoptotic effect of lauryl gallate is not dependent on DNA or protein synthesis, is not blocked by the chelation of calcium, and is not reverted by N-acetylcysteine.
Assuntos
Apoptose/efeitos dos fármacos , Ácido Gálico/farmacologia , Linfoma de Células B/metabolismo , Acetilcisteína/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Antioxidantes/química , Antioxidantes/farmacologia , Benzoquinonas , Western Blotting , Cálcio/metabolismo , Caspase 3 , Caspases/metabolismo , Bovinos , Membrana Celular/metabolismo , Separação Celular , Grupo dos Citocromos c/metabolismo , Citosol/metabolismo , DNA/efeitos dos fármacos , Fragmentação do DNA/efeitos dos fármacos , Diploide , Relação Dose-Resposta a Droga , Ativação Enzimática , Citometria de Fluxo , Conservantes de Alimentos/química , Conservantes de Alimentos/farmacologia , Ácido Gálico/análogos & derivados , Ácido Gálico/química , Glutationa/metabolismo , Herbicidas/farmacologia , Cinética , Lactamas Macrocíclicas , Linfoma de Células B/química , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Mitocôndrias/efeitos dos fármacos , Fosfatidilserinas/metabolismo , Poli(ADP-Ribose) Polimerases/metabolismo , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Quinonas/farmacologia , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Rifabutina/análogos & derivados , Cloreto de Sódio/farmacologia , Fatores de Tempo , Transfecção , Células Tumorais CultivadasRESUMO
BACKGROUND: Since the identification of tissue transglutaminase (tTG) as the antigen for the anti-endomysial antibodies (EMA), several antigen-specific immunoassays have been reported for celiac disease (CD) screening. A first objective was to evaluate the suitability for CD screening of three different IgA tTG ELISAs, two of them based on guinea pig liver tTG (gp-tTG) (an in-house ELISA with a partially purified extract and a commercial ELISA with purified gp-tTG antigen) and a third recombinant human tTG (rh-tTG) ELISA. The results are compared with EMA and with the final clinical diagnosis. A second objective was to analyze antibody reactivities in those patients with anti-tTG and EMA discrepancies. METHODS: ELISA and EMA tests were used to measure IgA anti-tTG levels in sera from 259 patients (107 had CD and 72 had Type I diabetes mellitus). RESULTS: The purified gp-tTG ELISA was highly sensitive (97.7%) and specific (98.8%) in the detection of CD, almost equaling EMA. Rh-tTG ELISA did not improved the sensitivity of EMA, but its specificity was slightly superior. Immunoblot analysis with partially purified gp-tTG extract, the antigen most frequently used for anti-tTG detection, showed that the majority of false positives were due to IgA reactivities to contaminant proteins present in the liver antigenic extract. This low specificity was particularly problematic in diabetics. CONCLUSION: Purified tTG ELISAs, either with purified guinea pig liver or recombinant human antigens, can be used as quantitative and observer-independent alternatives to the traditional and time-consuming EMA in the screening of CD.
Assuntos
Doença Celíaca/diagnóstico , Doença Celíaca/imunologia , Imunoglobulina A/sangue , Intestinos/patologia , Transglutaminases/imunologia , Western Blotting , Doença Celíaca/complicações , Diabetes Mellitus Tipo 1/imunologia , Ensaio de Imunoadsorção Enzimática , Humanos , Intestinos/ultraestrutura , Microvilosidades/patologia , Músculo Liso/patologia , Estudos Retrospectivos , Sensibilidade e EspecificidadeRESUMO
Homopurine DNA sequences are highly structurally polymorphic. In particular, d(GA)n DNA sequences are known to be capable of forming intramolecular foldbacks, bimolecular homoduplexes, and tetrastranded complexes. Counterions play a determinant role on the equilibria between the different structural conformers of d(GA)n sequences. In this paper, the effect of divalent zinc cations on the structure of a d(GA)20 oligonucleotide has been analyzed by CD spectroscopy and polyacrylamide gel electrophoresis. Depending on the precise experimental conditions at which zinc is added, two distinct conformations of the d(GA)20 oligonucleotide are stabilized. At neutral pH in the absence of zinc, d(GA)20 is partially organized into intramolecular foldbacks and bimolecular homoduplexes [Casasnovas et al. (1993) J. Mol. Biol. 233, 671-681]. Under these conditions, addition of zinc results in the stabilization of the bimolecular homoduplex which is nonspecific for zinc since it is also stabilized by divalent magnesium cations, increasing ionic strength, or decreasing pH. Its CD spectrum is identical to that reported earlier for parallel-stranded d(GA)n homoduplexes [Rippe et al. (1992) EMBO J. 11, 3777-3786]. On the other hand, if zinc is added under conditions where the d(GA)20 oligonucleotide is exclusively single-stranded, a different bimolecular homoduplex appears which is only observed in the presence of zinc. The zinc-specific duplex melts cooperatively, and, in contrast to the nonspecific duplex, its thermostability is high. Transition from the nonspecific to the zinc-specific duplex is observed at high zinc concentrations or at high temperatures. The transition is cooperative. These results are discussed in the context of the specific cation effects on the formation of intramolecular R.R.Y triplexes at d(GA.TC)n DNA sequences.
Assuntos
DNA/química , Conformação de Ácido Nucleico/efeitos dos fármacos , Ácidos Nucleicos Heteroduplexes/efeitos dos fármacos , Zinco/farmacologia , Animais , Dicroísmo Circular , HumanosRESUMO
Catalase (hydrogen peroxide:hydrogen peroxide oxidoreductase, E.C. 1. 11.1.6) is present in most aerobic prokaryotic and eukaryotic cells. Despite a large number of studies on catalases, the only mammalian catalase structure available is that from beef liver, in which about 50% of the haem groups are degraded to bile pigments. Three different crystal forms of human erythrocyte catalase were obtained by the hanging-drop vapour-diffusion technique using PEG as precipitant. Monoclinic crystals, with space group P21 and unit-cell parameters a = 102.9, b = 140.0, c = 173.6 A and beta = 103.2 degrees, require NADP(H) in the crystallization solution. Two types of hexagonal packing, with unit-cell parameters of either a = b = 86. 9, c = 255.5 A or a = b = 90.0, c = 521.2 A, were obtained under identical crystallization conditions in the absence of NADP(H). Only one diffraction data set could be collected: this was obtained from the hexagonal crystals with the smaller c axis using synchrotron radiation, with resolution to 2.65 A. A molecular-replacement solution, determined using a modified beef-liver catalase model as a search structure, corresponds to space group P6422 and contains a single subunit in the asymmetric unit, with an estimated solvent volume of about 50%. The packing determined suggests how minor rearrangements might allow the transition between both hexagonal crystal forms and provides an explanation for the anisotropic character of the corresponding diffractions.