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Results for “Condensates”

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At least 505 records · Page 28Linked to original sources

PubMed1987

Chromosome condensation may enhance X-ray-related cell lethality in a temperature-sensitive mutant (tsBN2) of baby hamster kidney cells (BHK21).

In the tsBN2 cell line, which has a temperature-sensitive defect in the regulatory mechanism for chromosome condensation, the lethal effect of X rays was enhanced by incubating the cells at a nonpermissive temperature (40 degrees C) following X irradiation. This enhancement was suppressed in the presence of cycloheximide, which inhibits induction of premature chromosome condensation. The findings obtained in the case of delayed incubation at 40 degrees C and in synchronized cells indicate that X-ray-related potentially lethal damage, which can be expressed by chromosome condensation, is produced in the cells at any stage of the cell cycle, but it is repairable for all cells except those at around the late G2-M phase, where chromosome condensation occurs at a permissive temperature (33.5 degrees C). These observations suggest that the high sensitivity of late G2-M cells to X rays is caused by the events associated with chromosome condensation.

Animals↗

PubMedDate not supplied

[Properties of mouse spleen residual condensed chromatin associated with the nuclear matrix].

Properties of condensed residual chromatin of mouse spleen, a component of residual nuclear structures, were studied. Extraction of the structures with buffers of different NaCl concentrations showed that the condensed chromatin consists of condensed nucleosomal chains. On increasing the ionic strength the complexes gradually fell apart into separate nucleosomal chains. DNA of condensed chromatin was accessible to staphylococcal nuclease and DNAase I, but digestion of this DNA was not accompanied by solubilization of the residual chromatin. Besides the essentially decreased total content of nonhistone chromosomal proteins the condensed chromatin practically did not contain HMG proteins. The nucleosome repeat length of this chromatin was shorter than that of chromatin solubilized by staphylococcal nuclease.

Animals↗

PubMedDate not supplied

[Electron microscope study of chromatin in hepatocyte nuclei during the first hours after partial hepatectomy. V. Changes in the relative area of condensed chromatin and the density of chromatin fibril packing in the ultrathin sections].

The degree of chromatin condensation was studied on ultrathin cell sections of guinea pig hepatocytes during the prereplicative period after partial hepatectomy. Three time points were chosen for analysis namely 2,5, 5 and 9 hrs after operation since they show marked increasing (2.5 hrs), decreasing (5 hrs) and repeated increasing (9 hrs) of the amount of ethidium bromide binding to chromatin. The degree of chromatin condensation was determined by measuring the area occupied by condensed chromatin and also by measuring the number of chromatin fibrils per a certain length. The condensed chromatin with varying localization in the nucleus were studied separately. The changes of nucleoplasmic chromatin were most pronounced: at 2.5 and 9 hrs after operation the decrease of the relative area and of the density of chromatin fibrils package was observed; these parameters were near to control at 5 hrs after operation. In general the changes in nucleoplasmic chromatin were correlated with the changes of the activity of the chromatin in the whole nucleus. The decondensation of the perimembranous chromatin was manifested in the decrease of its area and was expressed only at 9 hrs after operation. The perinucleolar chromatin was found to show the gradual decondensation which was manifested mainly by the decrease of its relative area. Thus the condensed chromatin seems to be a labile structure which undergoes essential changes in the process of the exit of the hepatocytes from G0-stage of the cell cycle, during the prereplicative period.

Animals↗

PubMed1980

Role of SS bridges in mitotic condensation of chromatin.

The effects of beta-mercaptoethanol on the mitotic index, phase index, condensation of chromatin in late G2 phase and in metaphase chromosomes, and on the content of protein -SH groups in successive developmental stages of antheridial filaments of Chara vulgaris L. were investigated. It has been shown earlier that as the development of antheridial filaments proceeds, the content of condensed chromatin in the late G2 phase increases, prophase duration shortens and metaphase chromosomes become more condensed. As cytophotometric measurements have shown, the concentration of the protein -SH groups is similar in all developmental stages, their total content, however, decreases in parallel with the shortening of cell length in successive generations. The more advanced developmental stage of antheridial filaments, the higher increase in the concentration of the protein -SH groups is induced by 2 h incubation with beta-mercaptoethanol. After 2 h incubation with beta-mercaptoethanol, the surface area of condensed chromatin decreases in late G2 phase, but the number of chromocenters remains unchanged, beta-mercaptoethanol does not modify the mitotic index but, beginning from the 4-celled stage, it increases the prophase index. In 1-,2-,4- and 8-celled antheridial filaments after 2 h incubation with beta-mercaptoethanol the chromosomes show a lower degree of condensation in about 30% of metaphases.

Cell Cycle↗

PubMed1976

[Bond strength between nonprecious metal alloy and porcelain. Part (1). Bond strength with press condensing method (author's transl)].

For the purpose of finding out the method which is able to evaluate nonprecious metal/porcelain bond strength easily, Ceramco procelain was fused to casted Wiron "S" (3 mm diameter), by means of 5 types of press condensing methods; the bond strength was measured by pull out method and these condensing methods were compared. Results are follows: (1) No significant difference was observed between conventional condensing method and press condensing method (condensing pressure; 472-1 415 kg/cm2), and the bond strength of Ceramco Paint-O-Pake porcelain to Wiron "S" was about 245-369 kg/cm2. (2) Bond strength was decreased with the decrease of the fused length of procelain. (3) Bond strength was increased approximately three times, when specimens were mounted by dental stone.

Dental Alloys↗

PubMed1993

Variation in condensation pressure during clinical packing of amalgam restorations.

Clinical measurements were made of the condensation pressures applied by a specialist prosthodontist to each amalgam increment during the packing of two pinned Class II restorations. The technique employed involved taking simultaneous video recordings of the operative procedures and the output of a strain gauge stress measuring system attached to the plugger. The condensation pressure applied during each thrust of the plugger could then be related directly to a particular stage of the packing process. In Cavity A, a maxillary left second premolar, an "admix" amalgam containing both spherical and lathe-cut particles was used while Cavity B, a mandibular right first molar, was filled with a spherical particle amalgam. The measurements indicated that the condensation pressures applied decreased substantially as the filling of each cavity proceeded. A marked reduction accompanied the change from a 1.5 mm diameter to a 2.5 mm diameter plugger but in addition, the dentist modified the force applied to each plugger according to the particular task which he was undertaking. For Cavity A, the condensation pressure applied during the filling of the base of the mesial proximal box was 12.6 +/- 1.9 MPa whereas the final increment was subjected to a condensation pressure of only 2.2 +/- 0.7 MPa. Corresponding figures for Cavity B were 7.6 +/- 2.0 MPa and 1.9 +/- 0.5 MPa.

Dental Alloys↗

PubMed1994

Inhibition of the transforming ability of cigarette smoking condensate-treated human fetal lung DNA induced by oltipraz.

Rat-1 cells transfected by genomic DNA of human fetal lung explants treated with 100 micrograms/ml of oltipraz (5-(2-pyrazimyl)-4-methyl-1, 2-dithiol-3-thione) for 14 hr or 100 micrograms/ml of cigarette smoking condensate for 6 hr formed 0 to 8 transformation foci, respectively. If 100 micrograms/ml of oltipraz was added to culture of human fetal lung explants 8 hr prior to the treatment of cigarette smoking condensate, the Rat-1 cells transfected by genomic DNA of human fetal lung explants formed only two foci. In addition, the growth speed of Rat-1 cells transfected by genomic DNA of human fetal lung treated with both oltipraz and cigarette smoking condensate was lower than that transfected by cigarette smoking condensate-treated human fetal lung DNA. Our results indicate that oltipraz can block the irreversible change of human fetal lung DNA caused by cigarette smoking condensate, and the results suggest the possibility of using oltipraz as control in the experimental initiation of human lung carcinogenesis.

Animals↗

PubMed1993

Repair of newly condensed amalgam restorations.

This study investigated the tensile strength of the newly condensed amalgam repaired with newly triturated amalgam in different times. A separable plexiglass mold with a dumbbell shape "cavity" was prepared. Amalgam was condensed in the "cavity" and allowed to set for one hour before it was removed from the mold and used for control. Five controls were prepared. Five groups with five samples in each group were prepared. Amalgam was condensed in the first half of the "cavity" and 5, 15, 30, 60 minutes and 24 hours later newly triturated amalgam was condensed in the second half of the "cavity" for the 5, 15, 60 minutes and 24 hour group samples. All samples were allowed to set in the mold for one hour then removed and stored in 100% humidity condition at room temperature for 24 hours. Tensile strength was tested on the Instron testing machine. It was found that when the newly condensed amalgam was repaired in five minutes, it has 84% of the tensile strength and was not significantly different from the controls. When it was repaired in 15, 30, 60 minutes and 24 hours, the tensile strength was significantly lower than the controls and significantly different from the controls.

Analysis of Variance↗

PubMedDate not supplied

The tumor-producing effect of automobile exhaust condensate and fractions thereof. Part III: mathematical-statistical evaluation of the test results.

This paper deals with the mathematical-statistical evaluation of experiments devoted to the following problems: 1. To what extent is the carcinogenic potency of automobile exhaust gas condensate dependent on the dose? 2. What fractions (groups of substances) of the automobile exhaust gas condensate are mainly responsible for the carcinogenic potency? 3. To what extent can the potency be explained by fractions (or single substances)? In order to answer the above questions, the working group planned animal experiments (cf. Misfeld and Timm, 1973) and obtained, prepared, and fractionalized automobile exhaust gas condensate (Grimmer, 1978). The exhaust gas condensate and its fractions were dropped onto the skin of female CFLP mice (Brune et al., 1978). In view of the problems posed above, the aim of the mathematical-statistical evaluation was to establish the dose-response relations, to assess the combined effect, and to estimate the relative potency and the assumed potency. In particular, the hypothesis (basis for the separation process) that the potency of the entire exhaust gas condensate is mainly attributable to the fraction which contains the polycyclic aromatic hydrocarbons (nitromethane phase) was examined.

Animals↗

PubMed1996

[Apoptosis of HL-60 cells induced by Harringtonine: membrane blebs, nucleus blebs and chromatin condensation].

Using Video Enhancement Contrast (VEC) microscopy, we recorded the morphological changes of same HL-60 cell in the processes of apoptosis induced by harringtonine. Our results show that all of apoptotic cells need several nucleus blebs before their chromatin condensation. Every nucleus bleb is induced by a relative membrane bleb. The number of membrane blebs is much higher than that of nucleus blebs, so there are only some of membrane blebs which can induce nucleus blebs. It suggested that membrane and nucleus blebs probably are related to apoptotic chromatin condensation. After HL-60 cells pretreated with cytochalasin B(CB), apoptotic chromatin condensation delayed eight hours, but no membrane bleb, nucleus bleb and apoptotic body formed eventually. So membrane and nucleus blebs during apoptosis are related to microfilament re-organization and can accelerate apoptotic chromatin condensation, but are unnecessary for apoptotic chromatin condensation. All this suggested that nuclear changes and cytoplasmic changes during HL-60 cell apoptosis are independent.

Antineoplastic Agents, Phytogenic↗

PubMedDate not supplied

[An analysis of the asynchronous condensation of homologous chromosomes in patients with chromosomal anomalies and their parents].

The aim of investigation was to study asynchronous condensation of differentially segmented homologous chromosomes in lymphocytes of peripheral blood, as a variant of karyotype instability in families which has a children with multiple malformations and cytogenetic defects. Automatically calculated the correlation between every pair of homologous chromosomes. After that we made the correlation diagrams for all patients. Our study showed that children with multiple malformations and cytogenetic defects and their parents has low correlation of banding structure between homologs. The length and segmentation one of homologs in every pair is conform to more early condensation stage. We made a conclusion about presence of asynchronous condensation homologous chromosome. As a control we perform the same investigation of 6 families with healthy children. We found high correlation between homologous chromosomes, namely synchronous condensation homologous pairs in all patients of this group. Asynchronous condensation was found only in all members of families which has a child with cytogenetic defect.

Abnormalities, Multiple↗

PubMed2024

MX2 forms nucleoporin-comprising cytoplasmic biomolecular condensates that lure viral capsids.

Human myxovirus resistance 2 (MX2) can restrict HIV-1 and herpesviruses at a post-entry step through a process requiring an interaction between MX2 and the viral capsids. The involvement of other host cell factors, however, remains poorly understood. Here, we mapped the proximity interactome of MX2, revealing strong enrichment of phenylalanine-glycine (FG)-rich proteins related to the nuclear pore complex as well as proteins that are part of cytoplasmic ribonucleoprotein granules. MX2 interacted with these proteins to form multiprotein cytoplasmic biomolecular condensates that were essential for its anti-HIV-1 and anti-herpes simplex virus 1 (HSV-1) activity. MX2 condensate formation required the disordered N-terminal region and MX2 dimerization. Incoming HIV-1 and HSV-1 capsids associated with MX2 at these dynamic cytoplasmic biomolecular condensates, preventing nuclear entry of their viral genomes. Thus, MX2 forms cytoplasmic condensates that likely act as nuclear pore decoys, trapping capsids and inducing premature viral genome release to interfere with nuclear targeting of HIV-1 and HSV-1.

Humans↗

PubMed2004

Comparison of vertical with lateral condensation technique in obturation of root canal system.

OBJECTIVE: To compare vertical condensation with laterally condensed gutta-percha technique in obturation of root canal system. DESIGN: A comparative study. PLACE AND DURATION OF STUDY: The Armed Forces Institute of Dentistry (Operative Deptt), Rawalpindi. SUBJECTS AND METHODS: Fifty six human permanent extracted teeth were collected from central incisor to second molar from the both arches and in vitro root canal procedure was carried out. RESULTS: Warm vertical technique resulted in a uniform smooth surface and least observable space between gutta percha and canal wall, especially in middle and apical region. CONCLUSION: Root canal obturation by warm vertical condensation is better than cold lateral condensation.

Humans↗

PubMed1977

Pulmonary tumorigenesis in Syrian golden hamsters after intratracheal instillations with automobile exhaust condensate.

Syrian golden hamsters were intratracheally instilled once every two weeks for life with automobile exhaust condensate (AEC) at two dose levels. The condensate was prepared from the most common German passenger car driven in the Europa-Test cycle (simulated city driving) and contained 340 microgram/g benzo(a)pyrene (B(a)P). Despite the very low total dose of B(a)P received, all animals of both dosage groups developed multiple pulmonary adenomas. Electron microscopy revealed these tumors to resemble B(a)P induced pulmonary adenomas in their ultrastructure. Numerous condensate-laden macrophages in tumor and peripheral lung tissues indicated that little of the instilled condensate had been removed from the airways through mucociliary action.

Adenoma↗

PubMed1989

Condensation of hypertrophic chondrocytes at the chondro-osseous junction of growth plate cartilage in Yucatan swine: relationship to long bone growth.

Chondrocytes of the cartilaginous growth plate are found in a spatial gradient of cellular differentiation beginning with cellular proliferation and ending with cellular hypertrophy. Although it is recognized that both proliferation and hypertrophy contribute significantly to overall bone growth, mechanisms acting on the chondrocyte to control the timing, the rate, and the extent of hypertrophy are poorly understood. Similarly, mechanisms acting on the terminal chondrocyte to cause its death at the chondro-osseous junction have not been investigated. In this study we examine the condensation of terminal hypertrophic chondrocytes in proximal and distal radial growth plates of Yucatan swine at 4 weeks of age. The animals were raised in a controlled environment where activity and feeding patterns were synchronized to a given time in the light/dark cycle. We analyzed cellular condensation both as a function of circadian rhythms in a 24-hr time period, and as a function of overall rate of growth. The data suggest that the magnitude of circadian influences on long bone growth is significantly damped at the level of the hypertrophic chondrocyte compared to that seen by previous investigators studying circadian influences on chondrocytic proliferation. Secondly, the condensation of hypertrophic chondrocytes at the chondro-osseous junction varies inversely with rate of growth in length of the bone. At any time period, a higher percentage of terminal chondrocytes in the condensed form was found in the slower-growing of the two growth plates. We relate these findings to current hypotheses concerning controls of chondrocytic hypertrophy and possible controls over the timing of hypertrophic cell death.

Animals↗

PubMed2006

Condensation of nonstochiometric DNA/polycation complexes by divalent cations.

This study found that divalent cations induced the further condensation of partially condensed DNA within nonstochiometric polycation complexes. The addition of a few mmol of a divalent cation such as calcium reduced by half the inflection point at which DNA became fully condensed by poly-L-lysine (PLL) and a variety of other polycations. The effect on DNA condensation was initially observed using a new method, which is based on the concentration-dependent self-quenching of fluorescent moieties (e.g., rhodamine) covalently linked to the DNA backbone at relatively high densities. Additional analyses, which employed ultracentrifugation, dynamic light scattering, agarose gel electrophoresis, and atomic force microscopy, confirmed the effect of divalent cations. These results provide an additional accounting of the process by which divalent cations induce greater chromatin compaction that is based on the representation of chromatin fibers as a nonstoichiometric polyelectrolyte complex. They also offer a new approach to assemble nonviral vectors for gene therapy.

Calcium↗

PubMed1985

Denaturation and condensation of DNA in situ induced by acridine orange in relation to chromatin changes during growth and differentiation of Friend erythroleukemia cells.

DNA in situ is progressively denatured when the cells or nuclei are treated with increasing concentration of acridine orange (AO). This transition can be monitored by flow cytometry as a decrease in green fluorescence. The complexes of denatured DNA and AO undergo immediate condensation and aggregation; this step is manifested by appearance of red luminescence and formation of precipitates that can be detected by electron microscopy. The precipitates form preferentially in heterochromatin as well as in ribosomes and polysomes. Their formation and further aggregation affects cellular light scatter properties in both the forward and right-angle direction. The AO-induced DNA denaturation and condensation was studied in nuclei of Friend erythroleukemia cells from exponentially growing, differentiated or quiescent cells. The DNA in nuclei of quiescent cells, from plateau-phase cultures, was the most sensitive to denaturation; it denatured (measured by changes in luminescence) at an AO concentration between 50 and 80 microM with the midpoint of the transition (Cd) at 70 microM. DNA in nuclei of differentiated cells (dimethyl-sulfoxide-induced erythroid differentiation) was more resistant (Cd = 77-83 microM), whereas DNA in exponentially growing cells was the most resistant (Cd = 86 microM). Extraction of proteins with 0.1 M HCl at 0 degree C abolished the differences between the cells and shifted the transition to a lower AO concentration (Cd = 46 microM). For comparison, the midpoint transitions representing condensation of free, nucleic acids measured as light scatter changes occurred at 13, 22, 31 and 53 microM of AO, for rRNA, tRNA, and denatured and native-calf thymus DNA, respectively. Denaturation and condensation of DNA, which can be induced by AO either in isolated nuclei or viable permeabilized or fixed cells provides a new approach to discriminate cell subpopulations with different chromatin structure by flow cytometry. The molecular mechanisms of this phenomenon are discussed.

Acridine Orange↗

PubMed2004

FGF-2 signaling is sufficient to induce dermal condensations during feather development.

In a previous report, we showed that fibroblast growth factor-2 (FGF-2) is a signal produced by epidermal placode cells during feather development and that this growth factor can induce feathers in scaleless mutant skins that fail to form feathers due to a defective epidermis (Song et al., [1996] Proc Natl Acad Sci USA 93:10246-10249). Here, we test whether FGF-2 is sufficient to induce dermal condensations, structures that normally form under the control of signals from the epidermal placode and are identified on the basis of aggregation of cells, the expression of FGF receptor-1 and bone morphogenetic protein-2 transcripts and the cessation of proliferation of the condensed cells. By using denuded 8-day scaleless dermis as a test system, we have established that FGF-2 is sufficient to induce dermal condensation. We suggest that the primary effect of FGF-2 is an increase in cellular density mediated through cell migration, followed by the expression of dermal condensation-specific genes and cessation of cell proliferation. The FGF-2 effect can be abolished by heparin, suggesting the involvement of heparan sulfate proteoglycans (HSPGs) in growth factor signaling. The spatiotemporal expression of syndecan-3 during feather development suggests that this cell-surface HSPG may be involved in the response of competent embryonic skin dermis to FGF-2.

Animals↗