RESUMEN
BACKGROUND: Cognitive-behavioral therapy (CBT) is thought to be useful for chronic pain, with the pathology of the latter being closely associated with cognitive-emotional components. However, there are few resting-state functional magnetic resonance imaging (R-fMRI) studies. We used the independent component analysis method to examine neural changes after CBT and to assess whether brain regions predict treatment response. METHODS: We performed R-fMRI on a group of 29 chronic pain (somatoform pain disorder) patients and 30 age-matched healthy controls (T1). Patients were enrolled in a weekly 12-session group CBT (T2). We assessed selected regions of interest that exhibited differences in intrinsic connectivity network (ICN) connectivity strength between the patients and controls at T1, and compared T1 and T2. We also examined the correlations between treatment effects and rs-fMRI data. RESULTS: Abnormal ICN connectivity of the orbitofrontal cortex (OFC) and inferior parietal lobule within the dorsal attention network (DAN) and of the paracentral lobule within the sensorimotor network in patients with chronic pain normalized after CBT. Higher ICN connectivity strength in the OFC indicated greater improvements in pain intensity. Furthermore, ICN connectivity strength in the dorsal posterior cingulate cortex (PCC) within the DAN at T1 was negatively correlated with CBT-related clinical improvements. CONCLUSIONS: We conclude that the OFC is crucial for CBT-related improvement of pain intensity, and that the dorsal PCC activation at pretreatment also plays an important role in improvement of clinical symptoms via CBT.
Asunto(s)
Dolor Crónico/terapia , Terapia Cognitivo-Conductual , Giro del Cíngulo/fisiopatología , Imagen por Resonancia Magnética , Corteza Prefrontal/fisiopatología , Adulto , Mapeo Encefálico , Estudios de Casos y Controles , Dolor Crónico/fisiopatología , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Vías Nerviosas/fisiopatología , Psicoterapia de Grupo , Descanso , Regresión EspacialRESUMEN
When a polymer solution with volatile solvent is dried, skins are often formed at the surface of the solution. It has been observed that after the skin is formed, bubbles often appear in the solution. We conducted experiments to clarify the relation between the skin formation and the bubble formation. We measured the time dependence of the thickness of the skin layer, the size of the bubbles, and the pressure in the solution. From our experiments, we concluded that i) the gas in the bubble is a mixture of solvent vapor and air dissolved in the solution, ii) the bubble nucleation is assisted by the pressure decrease in the solution covered by the skin layer, and iii) the growth of the bubbles is diffusion limited, mainly limited by the diffusion of air molecules dissolved in the solution.
RESUMEN
BACKGROUND: During 2005-2007, we experienced sporadic isolations of multidrug-resistant (MDRP) Pseudomonas aeruginosa from wards in a general hospital in Hiroshima. The objective of this study was to analyze epidemiology relationships and the mode of spread of the strains. METHODS: Clonality was assessed using pulsed-field gel electrophoresis (PFGE) and serotyping. MICs were determined using the microdilution broth method. Investigations of the affected patients' movements and environmental sampling from the affected wards were conducted. RESULTS: An abrupt increase in MDRP isolations began at the end of 2005 and ended in February 2007. A total of 25 MDRP strains were sporadically isolated from nine wards. Fourteen strains were genotypically and serologically identical. Analysis of the patients' movements identified that six of the 14 MDRP-positive patients became positive for MDRP when they were in the intensive care unit (ICU), and two became positive after the patients moved from the ICU to another nursing unit. Four MDRP strains were isolated from patients who did not stay in the ICU and were in ward E6, which had the second highest number of isolations. In July 2006, environmental sampling of the hospital identified a toilet brush in ward E6 that was contaminated with MDRP that was genotypically and serologically identical to the clinical isolates. CONCLUSIONS: Our study suggests that the sporadic increase in MDRP isolates during 2005-2007 in the general hospital in Hiroshima was due to an epidemic of an MDRP clone. Continuity and spread of infection was probably due to cross infection and contamination in the hospital with the MDRP strain.
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Infección Hospitalaria/epidemiología , Farmacorresistencia Bacteriana Múltiple , Epidemias , Infecciones por Pseudomonas/epidemiología , Pseudomonas aeruginosa/aislamiento & purificación , Electroforesis en Gel de Campo Pulsado , Hospitales Generales , Humanos , Unidades de Cuidados Intensivos , Japón/epidemiología , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , SerotipificaciónRESUMEN
BACKGROUND: Kawasaki disease (KD) is an acute vasculitis of unknown etiology. Immunoregulatory abnormalities have been thought to contribute to its pathogenesis. Although treatment with intravenous immunoglobulin (IVIG) effectively prevents significant cardiac morbidity, the mechanism by which IVIG produces an effect in KD has yet to be fully elucidated. OBJECTIVE: To investigate the effects of IVIG on the immune system of patients with KD. PATIENTS AND METHODS: Eleven patients with KD (mean [SD] age, 2.2 [1.5] years) were enrolled in this prospective study and treated with high-dose IVIG therapy (2 g/kg in 1 or 2 infusions) during the acute phase of the disease. We examined immunological changes, with special reference to Ig levels and 2 previously unassessed cytokines: B cell-activating factor belonging to the tumor necrosis factor family (BAFF), and a proliferation-inducing ligand (APRIL). RESULTS: Clinical symptoms disappeared quickly in all cases, with no coronary artery abnormalities. IgA and IgM levels responded more rapidly than previously reported and reached a peak between the 3rd and 10th day after the start of IVIG treatment. The mean (SD) BAFF level was high before IVIG treatment (3234 [1904] pg/mL) and decreased significantly (1085 [257] pg/mL) after IVIG treatment, whereas the mean (SD) APRIL level before IVIG treatment (18.0 [10.0] ng/mL) rose significantly (120.6 [41.2] ng/mL). A significant inverse correlation between BAFF and APRIL was observed in patients with KD. CONCLUSIONS: These results suggest that IVIG may affect the pathogenesis of KD through alteration of BAFF/APRIL.
Asunto(s)
Factor Activador de Células B/metabolismo , Linfocitos B/metabolismo , Inmunoglobulinas Intravenosas/administración & dosificación , Síndrome Mucocutáneo Linfonodular/tratamiento farmacológico , Miembro 13 de la Superfamilia de Ligandos de Factores de Necrosis Tumoral/metabolismo , Factor Activador de Células B/genética , Linfocitos B/efectos de los fármacos , Linfocitos B/inmunología , Linfocitos B/patología , Niño , Preescolar , Humanos , Inmunoglobulina A/biosíntesis , Inmunoglobulina A/genética , Inmunoglobulina M/biosíntesis , Inmunoglobulina M/genética , Lactante , Síndrome Mucocutáneo Linfonodular/inmunología , Síndrome Mucocutáneo Linfonodular/fisiopatología , Estudios Prospectivos , Miembro 13 de la Superfamilia de Ligandos de Factores de Necrosis Tumoral/genéticaRESUMEN
The biological behaviour and prognostic factors of Merkel cell carcinoma (MCC) in 20 cats were studied. The tumours were surgically removed and histopathologically examined. The animals were 8 to 20 years old (median age: 14 years), and the tumours were predominantly located in the neck and head. Follow-up data were available in 17 cases, and 12 cats died within a year of surgery. The overall median survival time after resection was 243 days (range 16-360 days). Recurrence occurred in 11 cases, although 6 of them (55%) were found to be margin-negative. Possible metastasis occurred after the surgery in 10 cases, although 6 of them (60%) were found to be margin-negative. The histopathological features of MCC included tumour necrosis in 16 cases (80%), vascular invasion in 6 cases (38%) and high mitotic counts (median: 28.5 per high-power field). Irregular acanthosis was noted adjacent to the tumours in 9 cases (60%). Immunohistochemically, the tumour cells were positive for cytokeratin (CK) 20 and p63 in all cases, synaptophysin in 19 (95%) cases, and CK18 in 16 cases (80%). The study shows that feline MCC is associated with a poor prognosis and exhibited a strong tendency towards local recurrence, regional lymph node metastasis and distant spread.
Asunto(s)
Carcinoma de Células de Merkel/veterinaria , Enfermedades de los Gatos/patología , Neoplasias Cutáneas/veterinaria , Animales , Carcinoma de Células de Merkel/diagnóstico , Carcinoma de Células de Merkel/mortalidad , Carcinoma de Células de Merkel/patología , Enfermedades de los Gatos/diagnóstico , Enfermedades de los Gatos/mortalidad , Gatos , Femenino , Masculino , Pronóstico , Piel/patología , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/mortalidad , Neoplasias Cutáneas/patologíaRESUMEN
Surgery for pituitary tumours at our institution was performed by rhinosurgical route by combined procedure by otolaryngologist and neurosurgeons. A retrospective review of case records of patients who had endonasal endoscopic transphenoidal approach for pituitary tumours from September 1998 to December 2004 was performed. A total of 81 trans-sphenoidal surgeries were performed during this study period. Only 68 case records with adequate information were available for review, 56 patients were included in the study and 12 were excluded. There were 24 males (42%) and 32 females (58%). The ethnic distribution, were 29 Malays, 24 Chinese, 2 Indian and 1 others. The age ranged from 16 years to 76 years, with a mean of 46 years. The majority of our patients presented with visual symptoms (38), headache (28), menstrual cycle disturbance or impotence (14) and acromegalic features (16). Forty patients had macroadenoma (71%) and 16 had microadenomas (29%). Thirty-six patients out of 40 macro-adenomas had suprasellar extensions (90%). Only eleven patients had lumbar drain inserted prior to commencement of the surgery and the majority of these were macroadenomas. The common complications encountered were diabetes insipidus (4), cerebrospinal fluid leak (2), meningitis (3), epistaxis (2), septal perforation (2), intercavernous sinus haemorrhage (3) and anterior pituitary insufficiency (2). Our study reveals that endonasal trans-sphenoidal approach is a safe and effective method of management of pituitary adenomas.
Asunto(s)
Adenoma/cirugía , Hipofisectomía/métodos , Adolescente , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Hipofisarias/cirugía , Complicaciones Posoperatorias , Estudios Retrospectivos , Seno EsfenoidalRESUMEN
The stacking and hydrogen bonding abilities of Trp-(Gly)n-Glu (n = 0 approximately 3) for the interaction with 7-methylguanine (m7G) base were examined by fluorescence and 1H-NMR methods, and it was shown that they correlate with the distance between the Trp and Glu residues, and become most significant when both residues are separated from each other by two Gly residues (n = 2). Based on this insight, the sequence conserved between the human and yeast cap binding proteins (CBPs) was surveyed, and the sequence of Trp-Glu-Asp-Glu (No. 102-105 in human CBP) was selected as a probable site for the binding with mRNA cap structure. Thus, the stacking and hydrogen bonding abilities of Trp-Glu-Asp-Glu with m7G cap structure were examined by comparative experiments using its analogous peptides. The results showed that the fourth Glu residue is important not only for the construction of hydrogen bond pairing with m7G base but also for strengthening the stacking interaction between the Trp indole ring and m7G base. Taking account of the recognition analysis using the mutant CBP proteins by site-directed mutagenesis (Ueda, H., Iyo, H., Doi, M., Inoue, M., Ishida, T., Morioka, H., Tanaka, T., Nishikawa, S. and Uesugi, S. (1991) FEBS Lett. 280, 207-210), this cooperative interaction could be important for the recognition of mRNA cap structure.
Asunto(s)
Fragmentos de Péptidos/química , Caperuzas de ARN/química , ARN Mensajero/química , Proteínas de Unión al ARN/química , Secuencia de Aminoácidos , Animales , Cromatografía de Afinidad , Reactivos de Enlaces Cruzados , Glutamina/química , Guanosina/análogos & derivados , Guanosina/química , Humanos , Enlace de Hidrógeno , Espectroscopía de Resonancia Magnética , Ratones , Datos de Secuencia Molecular , Conformación Proteica , Proteínas de Unión a Caperuzas de ARN , Proteínas de Unión al ARN/genética , Espectrometría de Fluorescencia , Triptófano/químicaRESUMEN
In order to elucidate the substrate specificity of alanyl-tRNA synthetase, 5'-O-[N-(L-alanyl)sulfamoyl]adenosine (Ala-SA), an analogue of alanyl-AMP, was chemically synthesized. Its binding ability is similar to that of the substrate based on the inhibitory activity for the aminoacylation of alanyl-tRNA synthetase. Taking advantage of the stable sulfamoyl bond of Ala-Sa, compared with the highly labile aminoacyl bond of alanyl-AMP, the molecular conformation of the former inhibitor was studied by X-ray single crystal analysis. Crystal data are as follows: C13H19N7O7S.2H2O, space group C2, a = 39.620(6), b = 5.757(1), c = 20.040(3) A, beta = 117.2(1) degrees, V = 4065(9) A3, Z = 8, and final R = 0.065 for 2785 independent reflections of F(2)0 greater than or equal to 2 sigma (F0)2. In the crystal, the molecule is in a zwitterionic state with the terminal amino group protonated and sulfamoyl group deprotonated, and takes an open conformation, where the L-alanine moiety is located far from the adenosine moiety with gauche/trans and trans orientations about the exocyclic C(4')-C(5') and C(5')-O(5') bonds, respectively. The conformation of the adenosine moiety is anti for the glycosyl bond and C(3')-endo for the ribose puckering, and alanine is in the usually observed trans region for the psi torsion angle. The molecular dimensions of the sulfamoyl group are nearly the same as those of the phosphate group. The biological significance of the observed Ala-SA conformation is discussed in relation with the molecular conformation of tyrosyl-AMP complexed with tyrosyl-tRNA synthetase.
Asunto(s)
Adenosina/análogos & derivados , Alanina-ARNt Ligasa/metabolismo , Alanina/análogos & derivados , Adenosina/síntesis química , Adenosina/química , Adenosina/metabolismo , Alanina/síntesis química , Alanina/química , Alanina/metabolismo , Enlace de Hidrógeno , Indicadores y Reactivos , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Especificidad por Sustrato , Difracción de Rayos X/métodosRESUMEN
The three-dimensional structure of the quinoprotein methylamine dehydrogenase from Paracoccus denitrificans has been refined at 1.75 A resolution utilizing the DNA-based protein sequence. The final model incorporates 8034 atoms per molecule, including 552 molecules of solvent, and gives an R-factor of 0.163. The molecule is an H2L2 hetero-tetramer containing a non-crystallographic 2-fold axis of symmetry. The 373-residue H subunit is folded into seven repeats of a four-stranded antiparallel beta-sheet motif, arranged in a propeller-like pattern about a pseudo-7-fold rotational axis of symmetry. Each L subunit contains 131 residues folded in a tight structure composed of five beta-strands in two sheets and crosslinked by six disulfide bonds. In addition there is an intrasubunit covalent linkage between two tryptophan side-chains that form the unique redox center, tryptophan tryptophylquinone (TTQ). The active site contains the O-6 carbonyl of TTQ, the side-chains of Asp32L Asp76L, Tyr119L and Thr122L, and two solvent molecules. A potential "gate" (Phe55H) separates the closed active-site cavity from a channel containing a group of highly ordered water molecules to bulk solvent. Phe55H and Tyr119L, and a number of neighboring oxygen atoms, may also provide a binding site for monovalent cations that are known to affect the reactivity and spectral properties of TTQ as well as the oxidative half reaction. The overall reaction has been dissected into a number of discrete steps that may require participation by several individual amino acid residues in the active site acting as general acids and bases.
Asunto(s)
Proteínas Bacterianas/química , Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH/química , Paracoccus denitrificans/enzimología , Conformación Proteica , Secuencia de Aminoácidos , Sitios de Unión , Catálisis , Cationes Monovalentes/química , Cristalografía por Rayos X , Modelos Moleculares , Datos de Secuencia Molecular , Oxidación-Reducción , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Solventes , Relación Estructura-ActividadRESUMEN
Adrenomedullin is a novel vasodilatory peptide originally isolated from pheochromocytoma. Recently, we found that adrenomedullin acts as an autocrine/paracrine apoptosis survival factor for rat endothelial cells. In the present study, we show that adrenomedullin induces the expression of Max, a heterodimeric partner of c-Myc, which may contribute to its ability to rescue endothelial cells from apoptosis. Max is a basic-helix-loop-helix-leucine zipper protein that forms heterodimers with its alternative partners, Mad and Mxi-1, to behave as an antagonist for Myc-Max heterodimer through competition for common DNA targets. The expression of Max is reported to be constitutive and more stable than c-Myc, and serum induces immediate c-Myc stimulation followed by modest Max up-regulation. In quiescent rat endothelial cells, adrenomedullin stimulated the expression of Max without affecting c-Myc. Quantitation with real-time quantitative PCR detected on the ABI Prism 7700 Sequence Detection System revealed that adrenomedullin and calcitonin gene-related peptide (CGRP), as well as serum, up-regulated Max mRNA levels and that down-regulation of Max mRNA after serum deprivation was prevented by adrenomedullin. Neither adrenomedullin nor CGRP affected c-Myc expression. Transfection of a Max-expressing plasmid into endothelial cells rescued the apoptosis induced by serum deprivation. Neutralization with anti-adrenomedullin antiserum or blockade with a CGRP receptor antagonist, CGRP(8-37), reduced Max mRNA levels in growing endothelial cells and enhanced apoptosis after serum starvation. Introduction of an antisense oligodeoxynucleotide against Max mRNA using transferrin receptor-operated transfer led to inhibition of both adrenomedullin-induced up-regulation of Max transcripts and its cell survival effect, whereas random, sense, or missense oligonucleotides were without effect. The negative regulation of E-box-driven transcription by adrenomedullin was demonstrated by using preproendothelin-1 promoter containing c-Myc-Max binding consensus sequence; the promoter activity of preproendothelin-1 was reduced by cotransfecting Max- and Mad-expressing plasmids as well as addition of adrenomedullin and CGRP. The present results demonstrate that adrenomedullin antagonizes serum deprivation-induced endothelial apoptosis by up-regulation of the max gene in an autocrine/ paracrine manner.
Asunto(s)
Apoptosis , Péptido Relacionado con Gen de Calcitonina/farmacología , Proteínas de Unión al ADN/biosíntesis , Endotelio Vascular/citología , Péptidos/farmacología , Factores de Transcripción , Adrenomedulina , Animales , Aorta , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico , Sangre , Células Cultivadas , Proteínas de Unión al ADN/genética , Endotelio Vascular/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Secuencias Hélice-Asa-Hélice , Masculino , Oligodesoxirribonucleótidos Antisentido/farmacología , Proteínas Proto-Oncogénicas c-myc/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , TransfecciónRESUMEN
Activin, a dimer of the beta-subunits of inhibin, has been found to stimulate FSH secretion from the cultured pituitary cells. However, in vivo action of activin is poorly elucidated. Daily sc injections of 40 micrograms activin-A over a period of 1-3 days to intact immature female rats caused a significant increase in serum FSH, inhibin, estradiol, uterine weight, and ovarian FSH receptors. Daily sc injections of 5 micrograms or 20 micrograms activin-A for 6 days caused a marked increase in ovarian weight and the development of large ovarian follicles. However, daily sc injections of 20 micrograms activin-A to hypophysectomized immature female rats for 3 days induced no significant changes in ovarian and uterine weight, serum inhibin, estradiol, and progesterone levels. Simultaneous injections of both activin-A and 5 IU PMSG induced a significant increase in ovarian and uterine weight, serum inhibin, and estradiol levels, compared to simultaneous injections of both vehicle and PMSG in the hypophysectomized immature female rats. These results demonstrate that activin-A induces not only an increase of FSH secretion from the pituitary but also a direct autocrine or paracrine ovarian stimulation resulting in an increase of the number of ovarian FSH receptors and ovarian and uterine weight, as well as an increase in the level of inhibin and estradiol secretion from the ovary.
Asunto(s)
Inhibinas/farmacología , Ovario/efectos de los fármacos , Hipófisis/efectos de los fármacos , Activinas , Animales , Estradiol/sangre , Femenino , Hormona Folículo Estimulante/sangre , Tamaño de los Órganos/efectos de los fármacos , Ratas , Ratas Endogámicas , Útero/efectos de los fármacosRESUMEN
The aim of this study was to investigate the efficacy of pre- and posttreatment 99mTc-ethyl cysteinate dimer (99mTc-ECD) single photon emission computed tomography (SPECT) for predicting the ischemic outcome of embolic middle cerebral artery occlusion after treatment with local intraarterial thrombolysis. The authors examined 28 patients with a moderately ischemic area (ratio of affected regional activity to cerebellar activity (A/C ratio) of 0.4 to 0.7) determined using pretreatment SPECT, and with complete recanalization within 6 hours. Posttreatment dynamic and static SPECT studies were performed immediately after thrombolysis. The extent of the affected area outlined on pretreatment SPECT was used for the posttreatment SPECT images, and A/C ratios were calculated. The relative retention ratio of 99mTc-ECD in the affected area was also analyzed using posttreatment dynamic SPECT. Fourteen patients either without infarction or with small subcortical and basal ganglial infarction, 11 patients with medium or large cortical infarction, and 3 patients with hemorrhage were identified by follow-up computed tomography. Ischemic outcome correlated with the relative retention ratio of 99mTc-ECD more closely than either the pre- or posttreatment A/C ratios. In particular, a threshold value for the development of hemorrhage was distinct only in the relative retention ratio of 99mTc-ECD. Pretreatment 99mTc-ECD SPECT did not always predict the occurrence of hemorrhagic transformation, whereas dynamic 99mTc-ECD SPECT performed immediately after thrombolysis allowed clear identification of patients at risk for hemorrhagic transformation.
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Cisteína/análogos & derivados , Embolia Intracraneal/diagnóstico por imagen , Embolia Intracraneal/tratamiento farmacológico , Accidente Cerebrovascular/diagnóstico por imagen , Accidente Cerebrovascular/tratamiento farmacológico , Terapia Trombolítica , Tomografía Computarizada de Emisión de Fotón Único , Adulto , Anciano , Isquemia Encefálica/diagnóstico por imagen , Isquemia Encefálica/tratamiento farmacológico , Femenino , Fibrinolíticos/administración & dosificación , Estudios de Seguimiento , Humanos , Infarto de la Arteria Cerebral Media/diagnóstico por imagen , Infarto de la Arteria Cerebral Media/tratamiento farmacológico , Inyecciones Intraarteriales , Masculino , Persona de Mediana Edad , Compuestos de Organotecnecio , Valor Predictivo de las Pruebas , Radiofármacos , Activador de Tejido Plasminógeno/administración & dosificación , Resultado del TratamientoRESUMEN
The nucleotide sequence of the downstream flanking region of the mreD gene of Escherichia coli was determined. Two open reading frames (ORFs) were found, a 591-bp orfE and a 1467-bp orfF. Based on the sequence, it is suggested that the three mre genes (encoding the murein pathway), mreB, mreC and mreD, and these two ORFs possibly form an operon.
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Escherichia coli/genética , Genes Bacterianos , Peptidoglicano/genética , Secuencia de Aminoácidos , Secuencia de Bases , ADN Bacteriano , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Peptidoglicano/metabolismo , Plásmidos , Alineación de SecuenciaRESUMEN
In order to investigate the effect of the Pt(II) ion on the stacking interaction between tryptophan and a guanine base, the quenching of Trp fluorescence was monitored for some systems in the absence and presence of the metal ion, and the association constants were obtained by the analysis of Eadie-Hofstee plots. All spectral data suggested that the stacking interaction is enhanced by the Pt(II) coordination to the guanine N7 atom. The result indicates the importance of the metal ion as a bookmark in the specific recognition of a nucleic acid base by an aromatic amino acid residue.
Asunto(s)
Fluorescencia , Guanina/química , Platino (Metal)/química , Platino (Metal)/farmacología , Triptófano/química , Composición de Base , Compuestos de Platino/farmacología , Purinas/química , Triptófano/efectos de los fármacosRESUMEN
The three-dimensional similarity between two fundamental conformations, a dimeric antiparallel extended structure and a type I' beta-turn folded form, of enkephalin was examined by computer graphic and empirical energy calculation methods. By the rotation of Tyr and Phe side chains, one half of the former structure could mimic the three-dimensional form of the latter without a large loss of conformational energy. This result provides a new idea for considering the conformation of enkephalin suitable for the multiple opioid receptors. The active conformation of enkephalin for mu- and delta-opioid receptors is discussed in the light of the present study.
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Encefalinas , Encefalinas/metabolismo , Sustancias Macromoleculares , Conformación Molecular , Receptores Opioides/metabolismo , Receptores Opioides delta , Receptores Opioides mu , TermodinámicaRESUMEN
The interaction between T4 DNA and basic polypeptides was observed using fluorescence microscopy. Free DNA molecules exhibited random Brownian motion accompanying the conformational change. With the addition of polycation, such as histone and polyarginine, DNA molecules tended to shrink to become spherical shapes. The persistent lengths and the distributions of long axis lengths of DNA-polyarginine complexes were determined from the video images at various polyarginine concentrations. It is demonstrated that the conformation of DNA changes in a biphasic manner in the presence of polyarginine.
Asunto(s)
ADN Viral/química , ADN/química , Péptidos/farmacología , Cationes , ADN/efectos de los fármacos , ADN Viral/efectos de los fármacos , Cinética , Microscopía Fluorescente , Conformación de Ácido Nucleico , Soluciones , Fagos TRESUMEN
The interactions of DNA duplexes with 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), a potent mutacarcinogen isolated from tryptophan pyrolysate, have been studied using CD spectroscopy. The results are that (a) the spectral change of B-form DNA caused by the interaction with Trp-P-1 is biphasic, i.e. the enlargement of CD bands characteristic to the B-DNA conformation in the range of r ([Trp-P-1]/ DNA]) = 0-2.5, followed by the rapid transition to the non-B conformation at r > 2.5; (b) this transition degree of B to non-B conformation of DNA is not necessarily dependent on the G-C content; and (c) the salt-induced Z-DNA is transformed to B-DNA (0 < r < 0.1) and then to non-B-DNA (r > 5), depending on the concentration of Trp-P-1 added. These data indicate that the non-covalent interaction of Trp-P-1 with DNA is mainly dependent on the B-DNA conformation.
Asunto(s)
Carbolinas/química , ADN/química , Mutágenos/química , Triptófano/química , Secuencia de Bases , Dicroismo Circular , Técnicas In Vitro , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos/químicaRESUMEN
A new beta-lactam-inducible penicillin-binding protein (PBP) that has extremely low affinity to penicillin and most other beta-lactam antibiotics has been widely found in highly beta-lactam(methicillin)-resistant Staphylococcus aureus (MRSA). The gene for this protein was sequenced and the nucleotide sequence in its promoter and close upstream area was found to show close similarity with that of staphylococcal penicillinase, while the amino acid sequence over a wide range of the molecule was found to be similar to those of two PBPs of Escherichia coli, the shape-determining protein (PBP 2) and septum-forming one (PBP 3). Probably the MRSA PBP (Mr 76462) evolved by recombination of two genes: an inducible type I penicillinase gene and a PBP gene of a bacterium, causing the formation of a beta-lactam-inducible MRSA PBP.
Asunto(s)
Proteínas Bacterianas , Proteínas Portadoras/genética , Hexosiltransferasas , Meticilina , Muramoilpentapéptido Carboxipeptidasa/genética , Resistencia a las Penicilinas , Peptidil Transferasas , Recombinación Genética , Staphylococcus aureus/genética , Antibacterianos/farmacología , Composición de Base , Secuencia de Bases , ADN Bacteriano/genética , Escherichia coli/genética , Genes Reguladores , Hibridación de Ácido Nucleico , Proteínas de Unión a las Penicilinas , Penicilinasa/genética , Regiones Promotoras Genéticas , Homología de Secuencia de Ácido NucleicoRESUMEN
Simulations of the molecular dynamics of the [Met5]enkephalin monomer and dimer structures in water have been carried out. The dynamic trajectories have been analyzed in terms of the distances between intra- or intermolecular polar atoms. The time-correlated conformational transitions of an extended monomer structure have been converged into a stationary state among the beta-bend folded forms. However, the dynamics simulation of an extended antiparallel dimer structure has shown no noticeable conformation change. These results imply that both the beta-bend monomer and the extended dimer structures exist together as the fundamental conformation of enkephalins.