SEARCH · PubMed Health

Results for “Condensates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources

PubMed2002

Comparison of different gutta-percha root filling techniques: Thermafil, Quick-fill, System B, and lateral condensation.

OBJECTIVES: In this in vitro study, the core (gutta-percha or gutta-percha and carrier)/sealer ratio and the sealing ability were calculated for 4 different gutta-percha techniques: Thermafil, JS Quick-Fill, System B, and lateral condensation. STUDY DESIGN: One hundred single-rooted teeth were instrumented and obturated. Forty of the teeth were embedded in resin and sectioned horizontally at 1, 2,3, and 4 mm from the anatomic apex. Photographs were taken of each section, and the total area of the canal filled with core material or sealer was calculated. Sixty of the teeth were kept in wet storage for 90 days, after which the teeth were immersed in 2% methylene blue for 48 hours. The length of dye penetration was measured. RESULTS: Roots obturated with Thermafil and JS Quick-Fill contained significantly more core material than did those obturated with System B or with lateral condensation. The lateral condensation technique had the lowest core/sealer ratio (P < .05). Roots using Thermafil and Quick-Fill showed significantly less dye leakage than did the lateral condensation technique. CONCLUSIONS: Through use of these techniques in vitro, Thermafil and JS Quick-Fill with carrier and System B were found to be superior to the lateral condensation technique in terms of core/sealer ratio. Thermafil and Quick-Fill were superior to lateral condensation in terms of dye leakage.

Analysis of Variance↗

PubMed2001

Caspase cleavage of MST1 promotes nuclear translocation and chromatin condensation.

MST1, mammalian STE20-like kinase 1, is a serine/threonine kinase that is cleaved and activated by caspases during apoptosis. MST1 is capable of inducing apoptotic morphological changes such as chromatin condensation upon overexpression. In this study, we show that MST1 contains two functional nuclear export signals (NESs) in the C-terminal domain, which is released from the N-terminal kinase domain upon caspase-mediated cleavage. Full-length MST1 is excluded from the nucleus and localized to the cytoplasm. However, either truncation of the C-terminal domain, point mutation of the two putative NESs, or treatment with leptomycin B, an inhibitor of the NES receptor, results in nuclear localization of MST1. Staurosporine treatment induces chromatin condensation, MST1 cleavage, and nuclear translocation. Staurosporine-induced chromatin condensation is partially inhibited by expressing a kinase-negative mutant of MST1, suggesting an important role of MST1 in this process. Significantly, MST1 is more efficient at inducing chromatin condensation when it is constitutively localized to the nucleus by mutation of its NESs. Moreover, inhibition of MST1 nuclear translocation by mutation of its cleavage sites reduces its ability to induce chromatin condensation. Taken together, these results suggest that truncation of the C-terminal domain of MST1 by caspases may result in translocation of MST1 into the nucleus, where it promotes chromatin condensation.

Active Transport, Cell Nucleus↗

PubMed1990

Mitotic chromatin condensation in vitro using somatic cell extracts and nuclei with variable levels of endogenous topoisomerase II.

We report the development of a new method for producing mitotic extracts from tissue culture cells. These extracts reproducibly promote the condensation of chromatin in vitro when incubated with purified interphase nuclei. This condensation reaction is not species specific, since nuclei from chicken, human, and hamster cell lines all undergo chromatin condensation upon incubation with the extract. We have used this extract to investigate the role of DNA topoisomerase II (topo II) in the chromosome condensation process. Chromatin condensation does not require the presence of soluble topo II in the mitotic extract. However, the extent of formation of discrete chromosome-like structures correlates with the level of endogenous topo II present in the interphase nuclei. Our results further suggest that chromatin condensation in this extract may involve two processes: chromatin compaction and resolution into discrete chromosomes.

Animals↗

PubMed2006

Common pathway of chromosome condensation in Mammalian cells.

Chromatin folding in the interphase nucleus is not known. We compared the pattern of chromatin condensation in Indian muntjac, Chinese hamster ovary, murine pre B, and K562 human erythroleukemia cells during the cell cycle. Fluorescent microscopy showed that chromosome condensation follows a general pathway. Synchronized cells were reversibly permeabilized and used to isolate interphase chromatin structures. Based on their structures two major categories of intermediates were distinguished: (1) decondensed chromatin and (2) condensed chromosomal forms. (1) Chromatin forms were found between the G1 and mid-S phase involving veil-like, supercoiled, fibrous, ribboned structures; (2) condensing chromosomal forms appeared in the late-S, G2, and M phase, including strings, chromatin bodies, elongated pre-chromosomes, pre-condensed chromosomes, and metaphase chromosomes. Results demonstrate that interphase chromosomes are clustered in domains; condensing interphase chromosomes are linearly arranged. Our results raise questions related to telomer sequences and to the chemical nature of chromosome connectivity.

Animals↗

PubMed2003

Glom is a novel mitochondrial DNA packaging protein in Physarum polycephalum and causes intense chromatin condensation without suppressing DNA functions.

Mitochondrial DNA (mtDNA) is packed into highly organized structures called mitochondrial nucleoids (mt-nucleoids). To understand the organization of mtDNA and the overall regulation of its genetic activity within the mt-nucleoids, we identified and characterized a novel mtDNA packaging protein, termed Glom (a protein inducing agglomeration of mitochondrial chromosome), from highly condensed mt-nucleoids of the true slime mold, Physarum polycephalum. This protein could bind to the entire mtDNA and package mtDNA into a highly condensed state in vitro. Immunostaining analysis showed that Glom specifically localized throughout the mt-nucleoid. Deduced amino acid sequence revealed that Glom has a lysine-rich region with proline-rich domain in the N-terminal half and two HMG boxes in C-terminal half. Deletion analysis of Glom revealed that the lysine-rich region was sufficient for the intense mtDNA condensation in vitro. When the recombinant Glom proteins containing the lysine-rich region were expressed in Escherichia coli, the condensed nucleoid structures were observed in E. coli. Such in vivo condensation did not interfere with transcription or replication of E. coli chromosome and the proline-rich domain was essential to keep those genetic activities. The expression of Glom also complemented the E. coli mutant lacking the bacterial histone-like protein HU and the HMG-boxes region of Glom was important for the complementation. Our results suggest that Glom is a new mitochondrial histone-like protein having a property to cause intense DNA condensation without suppressing DNA functions.

Amino Acid Sequence↗

PubMed2004

DNA condensation monitoring after interaction with hoechst 33258 by atomic force microscopy and fluorescence spectroscopy.

DNA condensation was only observed after the addition of Hoechst 33258 (H33258) among various types of DNA binding molecules. The morphological structural change of DNA was found to depend on the H33258 concentration. On comparison of fluorescence spectrum measurements with AFM observation, it was found that fluorescence quenching of DNA-H33258 complexes occurred after DNA condensation. Additionally, we showed that DNA condensation by H33258 was independent of sequence selectivity or binding style using two types of polynucleotides, i.e. poly(dA-dT).poly(dA-dT) and poly(dG-dC).poly(dG-dC). Moreover, it was concluded that the condensation was caused by a strong hydrophobic interaction, because the dissolution of condensed DNA into its native form on dimethyl sulfoxide (DMSO) treatment was observed. This study is the first report, which defines the DNA condensation mechanism of H33258, showing the correlation between the single molecule scale morphology seen on AFM observation and the bulky scale morphology observed on fluorescence spectroscopy.

Bisbenzimidazole↗

PubMed2006

Condensation of DNA-actin polyelectrolyte mixtures driven by ions of different valences.

Multivalent ions can induce condensation of like-charged polyelectrolytes into compact states, a process that requires different ion valences for different polyelectrolyte species. In this work we examine the condensation behavior in binary anionic polyelectrolyte mixtures consisting of DNA coils and F-actin rods in the presence of monovalent, divalent, and trivalent ions. As expected, monovalent ions do not condense either component and divalent ions selectively condense F-actin rods out of the polyelectrolyte mixture. For trivalent ions, however, we observe a microphase separation between the two polyelectrolytes into coexisting finite-sized F-actin bundles and DNA toroids. Further, by increasing the DNA volume fraction in the mixture, condensed F-actin bundles can be completely destabilized, leading to only DNA condensation within the mixture. We examine a number of possible causes and propose a model based on polyelectrolyte competition for ions.

Actins↗

PubMed2005

Vortex lattices in planar Bose-Einstein condensates with dipolar interactions.

In this Letter, we investigate the effects of dipole-dipole interactions on the vortex lattices in fast rotating Bose-Einstein condensates. For single planar condensate, we show that the triangular lattice structure will be unfavorable when the s-wave interaction is attractive and exceeds a critical value. It will first change to a square lattice, and then become more and more flat with the increase of s-wave attraction, until the collapse of the condensate. For an array of coupled planar condensates, we discuss how the dipole-dipole interactions between neighboring condensates compete with quantum tunneling processes, which affects the relative displacement of two neighboring vortex lattices and leads to the loss of phase coherence between different condensates.

Journal Article↗

PubMed1993

Hyaluronan is inversely correlated with the expression of CD44 in the dermal condensation of the embryonic hair follicle.

Previously, we have shown that CD44 (the hyaluronan receptor) was involved in the degradation of hyaluronan. In the present study, we examined the distribution of CD44 and hyaluronan in the skin of embryonic and mature mice. During embryonic development, CD44 was prominently expressed by the condensed mesenchymal cells involved in the formation of the hair follicles, but was absent from the surrounding interstitial cells. The cells of the dermal condensation expressed CD44 throughout the development of the hair follicle; however, once the hair follicle reached maturity, the mesenchymal cells of the dermal papilla no longer expressed this molecule. In contrast to the above, the distribution of hyaluronan was reversed from that of CD44. Hyaluronan was widespread throughout the embryonic dermis, but was conspicuously absent from the regions of the dermal condensation. This arrangement persisted through the development of the hair follicle; however, in the mature hair follicle, hyaluronan reappeared in the dermal papilla. Thus, in the embryonic dermis, the expression of CD44 and hyaluronan were complementary to each other. However, in the adult skin, only minor changes were detected in the levels of CD44 and hyaluronan associated with the cells of the dermal condensation during the hair cycle. When organ cultures of embryonic mouse skin were treated with Streptomyces hyaluronidase, the interstitial mesenchymal cells became compacted, indicating that the removal of hyaluronan leads to the condensation of these cells. The results of this study are consistent with the hypothesis that the expression of CD44 by the inductive mesenchymal cells allows them to degrade hyaluronan in a localized region, leading to formation and maintenance of the dermal condensation.

Aging↗

PubMed2006

Chromosome condensation in the absence of the non-SMC subunits of MukBEF.

MukBEF is a bacterial SMC (structural maintenance of chromosome) complex required for chromosome partitioning in Escherichia coli. We report that overproduction of MukBEF results in marked chromosome condensation. This condensation is rapid and precedes the effects of overproduction on macromolecular synthesis. Condensed nucleoids are often mispositioned; however, cell viability is only mildly affected. The overproduction of MukB leads to a similar chromosome condensation, even in the absence of MukE and MukF. Thus, the non-SMC subunits of MukBEF play only an auxiliary role in chromosome condensation. MukBEF, however, was often a better condensin than MukB. Furthermore, the chromosome condensation by MukB did not rescue the temperature sensitivity of MukEF-deficient cells, nor did it suppress the high frequency of anucleate cell formation. We infer that the role of MukBEF in stabilizing chromatin architecture is more versatile than its role in controlling chromosome size. We further propose that MukBEF could be directly involved in chromosome segregation.

Chromosomal Proteins, Non-Histone↗

PubMed1973

Nucleoid condensation and cell division in Escherichia coli MX74T2 ts52 after inhibition of protein synthesis.

The reorganization of the bacterial nucleoid of an Escherichia coli mutant, MX74T2 ts52, was studied by electron microscopy after protein synthesis inhibition by using whole mounts of cell ghosts, ultrathin-sectioning, and freeze-etching. The bacterial nucleoid showed two morphological changes after chloramphenicol addition: deoxyribonucleic acid (DNA) localization and DNA condensation. DNA localization was observed 10 min after chloramphenicol addition; the DNA appeared as a compact, solid mass. DNA condensation was observed at 25 min; the nucleoid appeared as a cytoplasm-filled sphere, often opened at one end. Ribosomes were observed in the center. Giant nucleoids present in some mutant filaments showed fused, spherical nucleoids arranged linearly, suggesting that the tertiary structure of the nucleoid reflects the number of replicated genomes. Inhibitors which directly or indirectly blocked protein synthesis and caused DNA condensation were chloramphenicol, puromycin, amino acid starvation, rifampicin, or carbonyl cyanide m-chlorophenyl hydrazone. All inhibitors that caused cell division in the mutant also caused condensation, although some inhibitors caused condensation without cell division. Nucleoid condensation appears to be related to chromosome structure rather than to DNA segregation upon cell division.

Amino Acids↗

PubMed1996

Mitotic chromosome condensation.

In this chapter, we review the structure and composition of interphase and mitotic chromosomes. We discuss how these observations support the model that mitotic condensation is a deterministic process leading to the invariant folding of a given chromosome. The structural studies have also placed constraints on the mechanism of condensation and defined several activities needed to mediate condensation. In the context of these activities and structural information, we present our current understanding of the role of cis sites, histones, topoisomerase II, and SMC proteins in condensation. We conclude by using our current knowledge of mitotic condensation to address the differences in chromosome condensation observed from bacteria to humans and to explore the relevance of this process to other processes such as gene expression.

Amino Acid Sequence↗

PubMed2000

Restriction enzyme analysis of DNA methylation in "condensed" chromatin of Ha-ras-transformed NIH 3T3 cells.

Increased amounts of chromatin condensation (i.e., localized areas of high DNA density, or chromatin higher order packing state) have been described in NIH 3T3 cells transformed with the Ha-ras oncogene. The structural basis for this oncogene-mediated alteration in nuclear organization is unknown. Since DNA methylation is likely to be involved in regulating the nucleosomal level of DNA packaging, we studied the role of DNA methylation in higher-order chromatin organization induced by Ha-ras. CpG-methylated DNA content was estimated in "condensed" chromatin of Ha-ras-transformed NIH 3T3 cell lines which differ in ras expression and ras-induced metastatic ability but present approximately the same values of "condensed" chromatin areas. The question posed was that if DNA methylation were involved with the chromatin higher-order organization induced by Ha-ras in these cell lines, the methylated DNA density in the "condensed" chromatin would also be the same. The DNA evaluation was performed by video image analysis in Feulgen-stained cells previously subjected to treatment with Msp I and Hpa II restriction enzymes, which distinguish between methylated and non-methylated DNA. The amount of methylated CpG sequences not digested by Hpa II in "condensed" chromatin regions was found to vary in the studied ras-transformed cell lines. DNA CpG methylation status is thus suggested not to be involved with the higher order chromatin condensation induced by ras transformation in the mentioned NIH 3T3 cell lines.

3T3 Cells↗

PubMedDate not supplied

Quantitative assessment and repeatability of chlorine in exhaled breath condensate.

BACKGROUND: Airway condition is presumably reflected in epithelial lining fluid (ELF). Exhaled breath condensate (EBC) has been used as a surrogate marker of the composition of ELF. OBJECTIVES: This study aimed at assessing the technical repeatability of chlorine measurements in EBC and comparing two separate condensators (Ecoscreen and R Tube regarding recovery and repeatability. Furthermore, the association between condensate recoveries and variations in the airway status were scrutinized. METHODS: EBC was collected using two condensators from 10 healthy volunteers. In addition, 13 asthmatic patients produced EBC with or without an added resistance of 5 cm H2O (Res5), applied to the outflow tract of Ecoscreen. All tests were done in random order. Chlorine levels (analyzed by a coulometric technique) in EBC served as a tool for investigation. RESULTS: Chlorine was measurable in all samples. The coefficient of repeatability of chlorine measurements was <10%. Chlorine levels were higher in EBC obtained from R Tube (p < 0.001), and differences in recoveries and variability in chlorine levels were presumably related to technical differences in the condensators and not to the repeatability of chlorine measurements per se. Air-flow-dependent chlorine levels were obtained from healthy volunteers. Application of Res5, recruiting additional alveoli, resulted in increased recovery of the EBC volume, but not of chlorine, from those that had the most pronounced airway obstruction (p = 0.05). CONCLUSION: We conclude that by employing a sensitive analysis technique, chlorine is repeatedly measurable in EBC. We suggest that the bulk of chlorine in EBC originates from large airways and not from the alveolar area. Both condensators were comparable regarding repeatability but differed regarding chlorine recovery.

Adult↗

PubMed1977

Preleptotene chromosome condensation in mouse oogenesis.

In the embryonic mouse ovary, studies of meiotic onset reveal the existence of a preleptotene stage of chromosome condensation. This stage begins with the appearance of very fine and irregular filaments, which gather around the chromocenters constituted by centromeric heterochromatin. At maximal condensation the nucleus contains 40 compact chromosomal masses. Decondensation engenders the reappearance of filaments more dense and regular than those seen at the onset of the condensation stage. The filaments elongate while progressively taking on the appearance of leptotene-stage chromosomes. The oocytes at different phases of condensation stage represent 41% of the germ cels in the 13-day-old mouse embryo. This proportion reaches 63% at 14 days and then declines to 3% at 17 days. Spectrophotometric studies of the condensation-stage nucleus, following staining by the Feulgen reaction, indicated that the nucleus contains 4C DNA. This observation, together with the morphologic characteristics of this stage, suggests that the oocyte is already engaged in prophase. Time studies indicate that the condensation stage occurs immediately prior to leptotene.

Animals↗

PubMed1980

Freeze-fracture and thin-section study of condensing vacuoles in rat pancreatic acinar cells.

Early and late developmental forms of condensing vacuoles are prominent in the relatively low rate secreting acinar cells of suckling rat pancreas. These vacuoles, when studied in freeze-fracture replicas and ultrathin sections under standard processing conditions, showed a biphasic evolution. During the first stage the condensing vacuoles (referred to as CV1) enlarge, accumulating contents of rather low electron density. Fracture faces with irregular patterns, possibly the result of fusion (pinching off) of microvesicles with (from) the condensing vacuoles, were occasionally encountered. The infrequency of such images indicates that fusion-fission during the growth stage must be a very rapid event. One common type of surface irregularity is gibbosities (or convexities) in the P fracture face with complementary images in the E fracture face. The significance of these irregularities, which are in apparent discordance with the theory of microvesicular transport, is unclear. By the end of the growing period the condensing vacuoles are large and smooth-surfaced (referred to as CV2) with contents of intermediate electron density (between that of the initial growing stage and that of the mature zymogen granule). The number of intercalated particles on both the large irregularly surfaced CV1) and large smooth-surfaced condensing vacuoles (CV2) membranes is high and comparable to that of the Golgi saccule and endoplasmic reticulum membranes. During the second stage, the smooth-surfaced condensing vacuoles undergo volume reduction associated with progressive increase in the electron density of their contents, thus becoming zymogen granules. Concomitant with size reduction, the number of intercalated particles in the membranes with CV2 diminishes markedly. The process of membrane retrieval appears to be accomplished selectively by pinching off coated microvesicles heavily studded with intercalated particles.

Animals↗

PubMed2000

Increased nitrotyrosine in exhaled breath condensate of patients with asthma.

The reaction of nitric oxide (NO) and superoxide anions (O(2)(-)) in the airway results in the formation of peroxynitrite, a highly reactive oxidant species. Peroxynitrite reacts with tyrosine residues in proteins to form the stable product nitrotyrosine. We investigated whether nitrotyrosine in exhaled breath condensates may be increased in patients with asthma. Four groups of nonsmoking subjects were studied. We measured exhaled NO, nitrotyrosine, and leukotrienes concentrations in breath condensate in healthy nonatopic subjects (n = 15) and in patients with mild asthma (steroid naive, n = 15), moderate asthma (inhaled steroid treatment, n = 12), and severe asthma (oral steroid treatment, n = 12). Exhaled NO was increased significantly in patients with mild (19.2 +/- 2.7 ppb, p < 0.01) and moderate asthma (14.0 +/- 1.53 ppb, p < 0.05), as compared with normal control (6.58 +/- 0.61 ppb). The levels of LTC(4)/D(4)/E(4) and LTB(4) were increased significantly in patients with moderate and severe asthma treated with steroids. Nitrotyrosine concentrations were detectable (6.3 +/- 0.8 ng/ml) in breath condensate of normal subjects, and were increased significantly in patients with mild asthma (15.3 +/- 2.0 ng/ml, p < 0.01). However, the levels of nitrotyrosine in exhaled condensate were lower in patients with moderate (5.0 +/- 0.6 ng/ml) and severe asthma (3.3 +/- 0.6 ng/ml, p < 0.05). There was a significant correlation between nitrotyrosine in breath condensate and exhaled NO in patients with mild asthma (r = 0.65, p < 0.05). We conclude that nitrotyrosine formation in exhaled breath condensates may be a marker of oxidative stress in airways of asthma.

Adult↗

PubMed2002

Comparison of nasal and oral inhalation during exhaled breath condensate collection.

Analysis of exhaled breath condensate is a method for noninvasive assessment of the lung. Condensate can be collected with a nose clip (subjects inhale and exhale via the mouth) or without it (subjects inhale via the nose and exhale via the mouth), but the mode of inhalation may influence condensate volume and mediator levels. We compared condensate volume and adenosine, ammonia, and thromboxane B2 levels in young healthy volunteers (n = 25) in samples collected for 10 minutes from subjects with or without a nose clip. Patients with allergic rhinitis (n = 8) were also studied to assess the effect of upper airway inflammation on mediator levels. Adenosine, ammonia, and thromboxane B2 levels were determined by HPLC, spectrophotometry, and radioimmunoassay, respectively. Volume of condensate was significantly higher without nose clip than that with nose clip (mean +/- SD, 2321 +/- 736 microl and 1746 +/- 400 microl, respectively; p = 0.0001). We found no significant difference in any mediator levels between these two collection modes in healthy volunteers, but adenosine showed a tendency to differ between oral and nasal inhalation in patients with allergic rhinitis. Our data indicate that whereas a greater volume of condensate can be obtained when subjects inhale through their noses, the mode of inhalation does not influence mediator levels in young healthy volunteers, but may affect these levels in patients with allergic rhinitis.

Adenosine↗