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At least 667 records · Page 37Linked to original sources
PubMed1999

Specific binding of high-mobility-group I (HMGI) protein and histone H1 to the upstream AT-rich region of the murine beta interferon promoter: HMGI protein acts as a potential antirepressor of the promoter.

The high-mobility-group I (HMGI) protein is a nonhistone component of active chromatin. In this work, we demonstrate that HMGI protein specifically binds to the AT-rich region of the murine beta interferon (IFN-beta) promoter localized upstream of the murine virus-responsive element (VRE). Contrary to what has been described for the human promoter, HMGI protein did not specifically bind to the VRE of the murine IFN-beta promoter. Stably transfected promoters carrying mutations on this HMGI binding site displayed delayed virus-induced kinetics of transcription. When integrated into chromatin, the mutated promoter remained repressed and never reached normal transcriptional activity. Such a phenomenon was not observed with transiently transfected promoters upon which chromatin was only partially reconstituted. Using UV footprinting, we show that the upstream AT-rich sequences of the murine IFN-beta promoter constitute a preferential binding region for histone H1. Transfection with a plasmid carrying scaffold attachment regions as well as incubation with distamycin led to the derepression of the IFN-beta promoter stably integrated into chromatin. In vitro, HMGI protein was able to displace histone H1 from the upstream AT-rich region of the wild-type promoter but not from the promoter carrying mutations on the upstream high-affinity HMGI binding site. Our results suggest that the binding of histone H1 to the upstream AT-rich region of the promoter might be partly responsible for the constitutive repression of the promoter. The displacement by HMGI protein of histone H1 could help to convert the IFN-beta promoter from a repressed to an active state.

Adenine↗
PubMed1991

Influence of the surface potential on the purple membrane structure and activity.

The role of the divalent cations in the purple membrane is generally understood as the release mechanism of the blue form appearance. The reconstitution by cation addition leads to the recovery of the initial spectral properties. Numerous data are available in the literature on this matter but they are scattered, so that synthetic understanding is not easy. The role of divalent cations was studied through spectrophotometric titrations and electrophoretic mobility measurements, i.e., zeta potential valuations. Thus, correlations between the bacteriorhodopsin (bR) state and the whole membrane in equilibrium with a definite medium could be made. Deionization was not a fully reversible process. The absence of cations affect neither the rate of the M412 formation nor its lifetime but the yield of M412/bR was 50% lower. The number of protons involved in the blue to purple transition of both membranes was different and the reconstitution did not erase this difference. It was observed that the number of protons dissociated upon cation addition corresponded approximately to the number of positive charges removed by deionization. Electrophoretic mobility titrations showed large differences between the membranes, illustrating the influence of the surface charge density on the pK of the transition. Taking advantage of the reversible light adaptation process, the reciprocal influence of the charge density of the membrane surface and the retinal state in bR was shown. Specificity of the divalent cations was questioned by a direct substitution of them by imidazol, which left the membrane intact. The partial reversibility of the deionization, the decrease of the M412 yield, the differences in the titratable protons, and the nonstrict specificity toward divalent cations suggested that another unknown factor could be removed from the membrane.

Bacteriorhodopsins↗
PubMed2006

Aminoglycoside-induced reduction in nucleotide mobility at the ribosomal RNA A-site as a potentially key determinant of antibacterial activity.

Steady-state and time-resolved fluorescence techniques have been used to characterize the energetics and dynamics associated with the interaction of an E. coli 16 S rRNA A-site model oligonucleotide and four aminoglycoside antibiotics that exhibit a broad range of antibacterial activity. The results of these characterizations suggest that aminoglycoside-induced reduction in the mobility of an adenine residue at position 1492 of the rRNA A-site is a more important determinant of antibacterial activity than drug affinity for the A-site. This observation is consistent with a recently proposed model for the mechanism of protein synthesis inhibition by aminoglycosides that invokes a drug-induced alteration in the conformational equilibrium of the rRNA A-site (centered around the conserved adenine residues at positions 1492 and 1493), which, in turn, promotes an enhanced interaction between the rRNA and the minihelix formed by the tRNA anticodon and the mRNA codon, even when the anticodon is noncognate. Regarded as a whole, the results reported here indicate that the rational design of antibiotics that target the 16 S rRNA A-site requires consideration of not only the structure and energetics of the drug-RNA complex but also the dynamics associated with that complex.

2-Aminopurine↗
PubMed1999

Potential role for hyaluronan and the hyaluronan receptor RHAMM in mobilization and trafficking of hematopoietic progenitor cells.

Although the mechanism(s) underlying mobilization of hematopoietic progenitor cells (HPCs) is unknown, detachment from the bone marrow (BM) microenvironment and motility are likely to play a role. This work analyzes the motile behavior of HPCs and the receptors involved. CD34(+)45(lo/med)Scatterlo/med HPCs from granulocyte colony-stimulating factor (G-CSF)-mobilized blood and mobilized BM were compared with steady-state BM for their ability to bind hyaluronan (HA), their expression of the HA receptors RHAMM and CD44, and their motogenic behavior. Although RHAMM and CD44 are expressed by mobilized blood HPCs, function blocking monoclonal antibodies (MoAbs) identified RHAMM as a major HA binding receptor, with a less consistent participation by CD44. Permeabilization of mobilized blood HPCs showed a pool of intracellular (ic) RHAMM and a smaller pool of icCD44. In contrast, steady-state BM HPCs have significantly larger pools of icRHAMM and icCD44. Also, in contrast to mobilized blood HPCs, for steady-state BM HPCs, MoAbs to RHAMM and CD44 act as agonists to upregulate HA binding. The comparison between mobilized and steady-state BM HPCs suggests that G-CSF mobilization is associated with depletion of intracellular stores of HA receptors and modulates HA receptor usage. To confirm that mobilization alters the HA receptor distribution and usage by HPCs, samples of BM were collected at the peak of G-CSF mobilization in parallel with mobilized blood samples. HA receptor distribution of mobilized BM HPCs was closely matched with mobilized blood HPCs and different from steady-state BM HPCs. Mobilized BM HPCs had lower pools of icHA receptors, similar to those of mobilized blood HPCs. Treatment of mobilized BM HPCs with anti-RHAMM MoAb decreased HA binding, in contrast to steady-state BM HPCs. Thus, G-CSF mobilization may stimulate an autocrine stimulatory loop for HPCs in which HA interacts with basal levels of RHAMM and/or CD44 to stimulate receptor recycling. Consistent with this, treatment of HPCs with azide, nystatin, or cytochalasin B increased HA binding, implicating an energy-dependent process involving lipid rafts and the cytoskeleton. Of the sorted HPCs, 66% were adherent and 27% were motile on fibronectin plus HA. HPC adherence was inhibited by MoAbs to beta1 integrin and CD44, but not to RHAMM, whereas HPC motility was inhibited by MoAb to RHAMM and beta1 integrin, but not to CD44. This finding suggests that RHAMM and CD44 play reciprocal roles in adhesion and motility by HPCs. The G-CSF-associated alterations in RHAMM distribution and the RHAMM-dependent motility of HPCs suggest a potential role for HA and RHAMM in trafficking of HPCs and the possible use of HA as a mobilizing agent in vivo.

Blood Component Removal↗
PubMed1999

Surface Electrical Properties of Polystyrene Latex.

A polystyrene latex suspended in HCl has been studied by dielectric response and dynamic mobility measurements. The aim was to see if these data, along with previous results from other techniques, could be interpreted in a consistent way within the standard electrokinetic model to yield information about the surface electrical properties of the latex. It was found that the zeta-potentials deduced from dynamic mobility and conductivity measurements were reasonably consistent, but did not agree well with those deduced from the electrophoretic mobility. The use of a dynamic Stern layer did not improve the agreement to any great extent. It is conjectured that differences in the methods of preparation, in particular the use of centrifugation, may be responsible for some of the disagreement. The pH-dependence of the dynamic mobility was also investigated and found to be weak. The dielectric response measurements showed significant discrepancies from the predictions of the standard electrokinetic model in the kHz regime, and the dynamic Stern layer model with realistic parameters could not improve the agreement very much. However the experimental relaxation frequencies were in good agreement with the predictions of the theory. Copyright 1999 Academic Press.

Journal Article↗
PubMed1998

Tauroursodeoxycholic acid protects cholestasis in rat reperfused livers: its roles in hepatic calcium mobilization.

Tauroursodeoxycholic acid (TUDCA) is of potential benefit in cholestatic disorders. However, the effect of TUDCA on hepatic ischemia-reperfusion injury is unknown. We studied this subject with particular regard to its roles in hepatic calcium mobilization. Three doses of TUDCA were used with continuous intravenous infusion (1.0, 0.1, and 0.01 micromol/kg body weight/min). At 3 hr after 1 hr of ischemia and reperfusion in 70% rat liver, high-dose TUDCA reduced hepatic reperfused injury according to biochemical and histological findings and significantly increased bile flow after reperfusion. It significantly increased tissue calcium content and serum calcium concentration after reperfusion. Furthermore, it also enhanced biliary calcium concentration and total output during reperfusion. In conclusion, TUDCA has a salutary effect on ischemia-reperfusion injury of the liver. However, it is still unclear how the calcium mobilization induced by TUDCA is associated with the hepatoprotection against ischemia-reperfusion injury.

Animals↗
PubMed1983

The mobilization of social supports: some individual constraints.

The effects of two dispositional variables, locus of control and help-seeking beliefs, as well as sociodemographic variables, on the mobilization of social supports were examined in this study. With a sample of 308 women users of a neighborhood health center, information was gathered regarding social support contacts following stressful events occurring within the previous year. Results confirmed the importance of the two dispositional variables, with internal locus of control and positive beliefs in the benefits of help-seeking each being associated with more support mobilization, independent of the number of potential supporters available. In addition, the educational level of the respondents showed a direct, positive relationship to support mobilization. Tests for interactions revealed several interactions between sociodemographic variables and the dispositional variables or potential support. These interactions generally showed that the dispositional variables and levels of potential support had a greater impact on support mobilization for persons with higher educational achievement, higher incomes, or coming from English-speaking (vs. Spanish-speaking) backgrounds. Results are discussed in relation to current research on social support and differential vulnerability of individuals to the effects of stress.

Adaptation, Psychological↗
PubMed2003

Putative proteins related to group II intron reverse transcriptase/maturases are encoded by nuclear genes in higher plants.

The Arabidopsis thaliana nuclear genome sequence revealed several open reading frames encoding proteins related to group II intron-encoded reverse transcriptase/maturases. Here, we show via sequence alignments that at least four such open reading frames are conserved in the nuclear genomes of A.thaliana and Oryza sativa (rice) and that they encode putative proteins belonging to two different classes (nMat-1 and nMat-2), neither of which is associated with a group II intron RNA structure. The two nMat-1 proteins have reverse transcriptase, maturase and DNA endonuclease domains characteristic of canonical group II intron-encoded proteins, while the two nMat-2 proteins have reverse transcriptase and maturase domains linked to a novel C-terminal domain. Although some nMat proteins have mutations expected to inactivate intron mobility functions, all could potentially retain the RNA splicing function. These nuclear maturase-like proteins may be imported into organelles to function in group II intron splicing and/or they may have assumed other cellular functions. Nuclear-encoded maturases could regulate organellar gene expression and may reflect a step in the evolution of mobile group II introns into spliceosomal introns.

Amino Acid Sequence↗
PubMed1983

[Intraoperative electrophysiological localization of the origin of sinoatrial activity and examination of the location of the sinus node using microscope anatomic studies. Animal experiment study].

Many electrophysiological and histological investigations have demonstrated that post-operative dysrhythmias which occur in children with heart disorders requiring extensive surgical treatment in the area of the right atrium, are often caused by intraoperative lesions of the sinoatrial node. Accordingly, accurate determination of that epicardial area which is closest to the primary pacemaking area of the sinoatrial node could prevent injuries and, thus, reduce the risk of postoperative arrhythmias. To localize the relevant area we developed a method which is based on the mapping technique in a series of experiments in dogs. The electrophysiological results were confirmed by histological or gross anatomical methods. After right lateral thoracotomy in the fifth intercostal space, the epicardial surface of the right atrium is subdivided into numbered fields by means of an imaginary grid. The local electrical activities are recorded as bipolar electrograms with the aid of two tripolar electrode probes, one fixed on the epicardium of the right atrial appendage and one placed onto the individual grid fields by the investigator. Intervals thus occur between those potentials derived from the mobile electrode probe and those derived from the fixed probe. Electrical activity originating from the sinoatrial node arrives earlier at the individual fields lying closer to the node than at the field of the fixed probe at the atrial appendage. Thus, the individual field associated with the longest interval between probe potentials must lie closest to the sinoatrial node. An electronic device with digital display of the interval length has been developed which enables, within three minutes, determination of the individual field with the longest interval. Comparison of the digital values with those measured from the electrograms shows good agreement. The experiments were carried out on eleven sheep dogs and large mongrels. In seven cases the location of the sinoatrial node was determined by subsequent histological examination. The assumption that the area associated with the longest interval between the probe potentials lies closest to the primary pacemaking region of the sinus node could be confirmed, since in all these cases the cranial portion of the sinoatrial node was located in the field with the greatest interval measured. In the other four cases the sinoatrial node was localized by dissection with the aid of a stereomicroscope. In three of the four cases, the cranial part of the sinoatrial node was also situated in the field associated with the longest interval.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1999

Colloid Vibration Potential in a Concentrated Suspension of Spherical Colloidal Particles.

A relation between the dynamic electrophoretic mobility of spherical colloidal particles in a concentrated suspension and the colloid vibration potential (CVP) generated in the suspension by a sound wave is obtained from the analogy with the corresponding Onsager relation between electrophoretic mobility and sedimentation potential in concentrated suspensions previously derived on the basis of Kuwabara's cell model. The obtained expression for CVP is applicable to the case where the particle zeta potential is low, the particle relative permittivity is very small, and the overlapping of the electrical double layers of adjacent particles is negligible. It is found that CVP shows much stronger dependence on the particle volume fraction φ than predicted from the φ dependence of the dynamic electrophoretic mobility. It is also suggested that the same relation holds between the electrokinetic sonic amplitude of a concentrated suspension of spherical colloidal particles and the dynamic electrophoretic mobility. Copyright 1999 Academic Press.

Journal Article↗
PubMed2001

Zeta Potential of Highly Charged Thin Double-Layer Systems.

Electrophoretic measurements under d.c. conditions involve a fundamental ambiguity for particles with a high zeta potential; two very different values of zeta potential can be ascribed to the same mobility. In the case of a polystyrene sulfate latex studied previously, selecting the higher (absolute) value gave a more consistent picture of the interface and also removed an anomaly in the electrokinetic behavior as a function of indifferent electrolyte concentration. Confirmation that the higher value is the correct one, however, was still needed. The ambiguity is resolved unequivocally here by the use of high-frequency mobility measurements using electroacoustics, since the mobility spectra for the high and low zeta potentials are very different. The interpretation is supported by the dielectric relaxation spectra of this material in the megahertz region. Copyright 2001 Academic Press.

Journal Article↗
PubMed1999

Prolonged release and c-kit expression of haemopoietic precursor cells mobilized by stem cell factor and granulocyte colony stimulating factor.

Mobilization of haemopoietic precursor cells into the circulation by the combination of cytokines, stem cell factor (SCF) and G-CSF in previously untreated patients with carcinoma of the breast resulted in increased yield of collected peripheral blood precursor cells (PBPC). This mobilization of PBPC by SCF with G-CSF lasted several days after ceasing the cytokines in comparison to the rapid fall of PBPC after ceasing G-CSF. Possible mechanisms for this increased and prolonged mobilization were investigated. Immunological phenotyping with CD38, Thy-1 and MDR-1 of the CD34-positive mobilized PBPC detected no difference in maturity compared to PBPC mobilized by G-CSF alone. However, the down-regulation of c-kit, which is associated with the mechanism of mobilization, was much greater in the PBPC mobilized by SCF and G-CSF. The potential clinical implication of increased and prolonged mobilization is increased yield, allowing transplantation of heavily pre-treated patients, transplantation with PBPC from a single apheresis, or PBSC support for multiple courses of high-dose therapy from one mobilization procedure.

Antigens, CD34↗
PubMed2001

Does temporary splinting before non-surgical therapy eliminate scaling and root planing-induced trauma to the mobile teeth?

The objective of this study was to determine whether temporary splinting of periodontitis-affected mobile teeth, prior to non-surgical mechanical therapy, affects treatment outcome by eliminating scaling and root planing-induced trauma to the teeth. Mandibular anterior teeth of 29 patients (15 females; 14 males; age range 30 to 48 years) with adult periodontitis were evaluated. Clinical measurements were performed at 4 sites per tooth including mesial, distal, buccal and lingual aspects at baseline, 3 and 6 months after treatment. The following clinical parameters were analyzed: plaque index (PI), gingival index (GI), bleeding on probing (BOP), pocket depth (PD), probing attachment level (PAL), gingival margin level (GML) and tooth mobility (TM). Patients were randomly divided into 3 groups: i) group 1 (n = 8) received scaling and root planing (SRP) only, ii) group 2 (n = 10) received scaling and root planing before splinting and iii) group 3 (n = 11) received scaling and root planing after splinting. Statistical analysis revealed that there were no significant differences among the groups for either bleeding on probing or probing attachment level values at any of the time intervals. At the end of the study, the greatest decrease in pocket depth was noted in group 2 (1.24+/-0.10 mm) which was thought to be the result of gingival recession (0.73+/-0.07 mm). Group 1 was the only group that showed reduction in tooth mobility at 3 months compared to baseline (1.67+/-0.55 PTV units). Group 3 displayed the least reduction in tooth mobility during the entire study period (0.26+/-0.44 PTV units). In conclusion, splinting of mobile teeth before SRP, and thereby elimination of potential SRP-induced trauma to the mobile teeth, did not show any adjunctive effect on healing when compared to splinting after SRP. Thorough debridement of root surfaces, even performed in the presence of increased mobility, resulted in improvements in clinical parameters, i.e. mechanical manipulation of mobile teeth during periodontal treatment did not affect clinical outcome negatively.

Adult↗
PubMed2002

Women's receptivity to church-based mobile mammography.

Mobile mammography can increase access to preventive screening and might be effective in church-based settings. Among 1,117 women ages 50 to 80 from 45 Los Angeles County churches, 31.7 percent said they would definitely use a mobile van at church, 21.9 percent would probably use one, 28.7 percent would probably not use one, and 17.6 percent would definitely not use one. The odds of saying yes to mobile mammography were six times higher for Spanish-speaking Latinas than for whites, over two times higher for English-speaking nonwhites than for whites, five times higher for the uninsured than for those with public or private health insurance, and three times higher for women who reported no mammogram in the previous 24 months than for women who reported a mammogram. Partnering with churches to provide mobile mammography offers the potential to increase screening adherence for traditionally underscreened women.

Aged↗
PubMed2007

Reversible vesicle restraint in response to spatiotemporally controlled electrical signals: a bridge between electrical and chemical signaling modes.

Microelectronic devices employ electrons for signaling whereas the nervous system signals using ions and chemicals. Bridging these signaling differences would benefit applications that range from biosensing to neuroprosthetics. Here, we report the use of localized electrical signals to perform an operation common to chemical signaling in the nervous system. Specifically, we employ electrical signals to restrain vesicles reversibly. We perform this operation using the stimuli-responsive aminopolysaccharide chitosan that is able to electrodeposit onto cathode surfaces in response to localized electrical stimuli. We show that surfactant-vesicles and liposomes can be co-deposited with chitosan and are entrapped (i.e., restrained) within the deposited film's matrix. Vesicle co-deposition could be controlled spatially and temporally using microfabricated wafers with independent electrode addresses. Finally, we show that vesicles restrained within the deposited chitosan matrix can be mobilized under mildly acidic conditions (pH <6.5) that resolubilize chitosan. Potentially, the ability to restrain and mobilize chemical signals that are segregated within vesicles may allow microfluidic systems to access the rich diversity offered by chemical signaling.

Animals↗
PubMed1998

Peripheral blood progenitor cells for autologous transplant in children.

Autologous peripheral blood progenitor cell transplantation has become an accepted procedure to support high dose chemotherapy in adults and children with cancer. The use of hematopoietic growth factors alone for mobilization of PBSC avoids the potential side effects of myelotoxic regimens and is as effective in reconstituting hematopoiesis as other mobilization methods. Many problems associated with apheresis procedures arise when PBPCs are harvested in small children. Large-volume-leukapheresis using a continuous flow blood cell separator allows us the collection of peripheral blood stem cells in children, even in the small ones. The speed of hematological recovery highly correlates with the number of CD34+ infused cells. We consider that a CD34+ cell dose of 5.0 x 10(6)/kg may be sufficient to ensure a rapid neutrophil and platelet recovery in pediatric patients mobilized by G-CSF.

Antigens, CD34↗
PubMed2006

Determination of hesperidin in Pericarpium Citri Reticulatae by semi-micro HPLC with electrochemical detection.

Determination of hesperidin contents in Pericarpium Citri Reticulatae was performed by a simple extraction with methanol and semi-micro high-performance liquid chromatography with electrochemical detection (muHPLC-ECD). Chromatography was performed using a microbore octadecylsilica (ODS) column, methanol-water-phosphoric acid (40:60:0.5, v/v/v), as a mobile phase and applied potential at +0.9 V versus Ag/AgCl. Peak heights were found linearly related to the concentrations of hesperidin injected 9.16 ng/ml to 3.06 microg/ml (r>0.999). The detection limit (S/N=3) was 3.06 ng/ml (15.3 pg). Hesperidin of 305 ng/ml was detected with a relative standard deviation (R.S.D.) of 0.79% (n=5). Hesperidin in Pericarpium Citri Reticulatae was extracted with methanol, diluted with the mobile phase, and injected into the muHPLC-ECD for determination. The hesperidin content of Pericarpium Citri Reticulatae from four different districts in China were determined with R.S.D. of 3.59%, 2.29%, 2.36%, and 2.32% (n=5), respectively. Recoveries of hesperidin from the four Pericarpium Citri Reticulatae sources were 100.3%, 99.83%, 100.7%, and 100.6%, respectively. This method is useful for the determination of hesperidin in Pericarpium Citri Reticulatae, and especially so for instances when samples are sparse.

China↗
PubMed1996

The plasmid replicator AMA1 in Aspergillus nidulans is an inverted duplication of a low-copy-number dispersed genomic repeat.

The AMA1 sequence was isolated from a genomic library of Aspergillus nidulans on the basis of its ability to enhance transformation frequency and generate phenotypically unstable transformants in this fungus. These properties were previously shown to be the result of extrachromosomal replication of AMA1-bearing plasmids. Here we demonstrate that AMA1 is an inverted duplication of a sequence which has other isolated genomic copies. These sequences (mobile Aspergillus transformation enhancers, or MATEs) share a high degree of sequence similarity and exhibit some features characteristic of mobile elements, including a potential Met-tRNA priming site, similar to that found in retrotransposons of the Ty-copia group. The nucleotide sequence does not encode any extended polypeptides but contains ARS-consensus matches and a multiply repeated 'Spe' motif, which may be described as a symmetrically duplicated topoisomerase I recognition site. This motif was shown to be a target for illegitimate recombination events. The mobility of members of the MATE family is inferred from the observation that their chromosomal locations are highly variable between wild Aspergillus isolates. The inverted duplication AMA1 is present in laboratory strains derived from the Glasgow isolate but not in other wild isolates tested. This indicates that the inverted duplication AMA1 is of recent evolutionary origin and probably does not exert any conserved function in the chromosome. We discuss possible connections between structural features of AMA1 and its ability to promote extrachromosomal plasmid replication.

Amino Acid Sequence↗