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 559 records · Page 31Linked to original sources

PubMed1975

Examination of the limiting laws of polyelectrolytes and counterion condensation II.

The two phase model of polyelectrolyte solutions, which has been developed recently, is examined in a further detail. The binding free energy, which was introduced in the previous paper (J. Chem. Phys. 81 (1977) 1929), is replaced by the entropy of the condensed phase. This replacement leads to a detailed picture of the condensed phase. In a mixed system of mono- and divalent counterions, a couple of possibilities are examined in interpreting the condensation volume, which corresponds to the condensation entropy.

Journal Article↗

PubMed1985

The contribution of polycyclic aromatic hydrocarbon fractions with different boiling ranges to the carcinogenic impact of emission condensate from coal fired residential furnaces as evaluated by topical application to the skin of mice.

Flue gas condensate from briquet-fired residential furnaces was separated into a polycyclic aromatic compound (PAC)-free and a PAC-containing part, followed by a subfractionation of the PAC-containing fraction into 3 parts: PAC consisting predominantly of (a) 2 and 3 rings, (b) 4 and 5 rings and (c) 6 and more rings. To evaluate the carcinogenic potency of the condensate and its fractions, local application onto skin of mice in 2 or 3 doses was used. Since it was known from an earlier investigation that both the PAC-free fraction and the fraction containing PAC with 2 and 3 rings were almost ineffective, only PAC-fractions containing more than 3 rings were tested. The probit and Weibull analysis of the results showed that the condensate and the fractions containing PAC with 4 and 5 rings as well as 6 and more rings provoke local tumors after repeated application to the dorsal skin of mice. The tumor incidence exhibited a clear cut dose-response relationship. Fractions (b) and (c) were almost equally active, each contributing by about 50% to the total carcinogenicity. The content of benzo[a]pyrene (0.72 mg/g condensate) contributed by 10-11% to the total carcinogenicity of the emission.

Administration, Topical↗

PubMed1987

Contribution of polycyclic aromatic hydrocarbons and nitro-derivatives to the carcinogenic impact of diesel engine exhaust condensate evaluated by implantation into the lungs of rats.

Diesel exhaust condensate was separated by a liquid-liquid distribution into a hydrophilic (I; about 25% by weight of the total condensate) and a hydrophobic part (II; about 75%-wt.). To evaluate the carcinogenicity, the proportionately dosed fractions have been implanted into the lungs of Osborne Mendel rats and compared with several doses of benzo[a]pyrene and the vehicle, a mixture of trioctanoin plus beeswax. Only the hydrophobic part which contained polycyclic aromatic compounds (PAC) resulted in 5 malignant tumors in a group of 35 animals. In addition, the hydrophobic part was separated by column chromatography on Sephadex LH 20 and subsequently on silica gel into several fractions, such as non-aromatic compounds plus PAC with 2 and 3 rings (IIa; 72%-wt of the total condensate), polycyclic aromatic compounds (PAH) with 4 and more rings (IIb; 0.8%-wt), polar PAC (IIc; 1.1%-wt) and nitro-PAH (IId; 0.7%-wt). PAH consisting of 4 and more rings (IIb) were found to be the most potent subfraction and provoked when proportionately dosed 6 carcinomas in a group of 35 rats. Only a low contribution to the carcinogenicity was observed by the subfraction of nitro-PAH (IId) which produced 1 carcinoma/35 rats. The polar PAC (IIc) and the fraction of non-aromatics plus PAC with 2 and 3 rings (IIa), although the main subfraction (72%-wt of the total condensate) did not provoke any tumors. The reconstitution of all hydrophobic subfractions (IIa-d) resulted in the same carcinogenic potency as the unfractionated hydrophobics (II), provoking 7 carcinoma in 35 rats. It may be concluded from these findings that most of the carcinogenicity of diesel exhaust originates from the PAH consisting of 4 or more rings.

Animals↗

PubMed1983

Role of polyamines during chromosome condensation of mammalian cells.

The objective of the present study was to investigate the role of polyamines in the process of chromosome condensation. The phenomenon of premature chromosome condensation (PCC) involving fusion between mitotic and interphase cells was used as the assay system. The factors present in the mitotic cells would bring about the breakdown of the nuclear membrane and condensation of the interphase chromatin into chromosomes, similar to that which occurs during the initiation of mitosis. Alpha-difluoromethyl ornithine (DFMO), a specific irreversible inhibitor of ornithine decarboxylase was used to deplete both mitotic and interphase cells of polyamines. The results indicate that the polyamine depleted mitotic cells have a diminished ability to induce PCC. This inhibition could easily be reversed by exogenous addition of polyamines at the time of fusion. Furthermore, exogenously added polyamines hastened the entry of exponentially growing cells into mitosis. These observations suggest an essential role for polyamines during the process of chromosome condensation of mammalian cells.

Chromosomes, Human↗

PubMed2005

The use of chitosan as a condensing agent to enhance emulsion-mediated gene transfer.

Previously we have formulated a new cationic emulsion, composed of 3beta [N-(N',N'-dimethylaminoethane) carbamoyl] cholesterol and dioleoylphosphatidyl ethanolamine, castor oil and Tween 80, and it efficiently delivered plasmid DNA into various cancer cells with low toxicity. Chitosan is a natural cationic polysaccharide and is able to form polyelectrolyte complexes with DNA, in which the DNA is condensed and protected against nuclease degradation. Based on these facts, chitosan was used as a condensing agent to enhance the transfection efficiency of cationic emulsion-mediated gene delivery vehicle. The particle size, zeta potential and transmission electron micrographs of DNA/emulsion complexes were observed before and after condensation by chitosan. In vitro transfection efficiency of naked or precondensed DNA/emulsion (pcDNA/E) complexes was investigated in human hepatoma cells (HepG2) using flow cytometer, confocal microscope and western blot. In addition, in vivo gene transfer was also evaluated as GFP mRNA expression by reverse transcriptase-polymerase chain reaction. The size of transfection complexes was reduced after the condensation of DNA by chitosan. Moreover, when the pcDNA/E complexes were administered into the mice, the GFP mRNA expression was prolonged in liver and lung until day 6. These results suggest that the use of chitosan enhance the in vitro transfection efficiency and extend in vivo gene transfer.

Animals↗

PubMed2005

Inhibition of Caco-2 colon, MCF-7 and Hs578T breast, and DU 145 prostatic cancer cell proliferation by water-soluble black bean condensed tannins.

The potential anti-angiogenic activities of water-soluble condensed tannins isolated from black beans were evaluated using HEL 299 normal human fibroblast lung cells, Caco-2 colon, MCF-7 and Hs578T breast, and DU 145 human prostatic cancer cells. Condensed tannins at 0.24-24 microM did not affect the growth of normal cells, but dose-dependently induced cancer cell death by apoptosis as shown by a concentration-dependent decrease in ATP and cell gross morphology. After 24h exposure to Caco-2, MCF-7, Hs578T, and DU 145 cancer cells, water-soluble black bean condensed tannins at 24 microM suppressed fetal bovine serum stimulated cell migration, the secretion of matrix metalloproteinase-2 (MMP-2 or gelatinase A), matrix metalloproteinase-9 (MMP-9 or gelatinase B), and vascular endothelial growth factor VEGF(165) receptor expression by the cancer cells in the conditioned media. The potential health enhancing properties of condensed tannins from black beans as inhibitors of angiogenesis is discussed.

Adenosine Triphosphate↗

PubMed2005

First investigations of mountainous cold condensation effects with the CliMoChem model.

We present first results of a modeling study to explore the occurrence and extent of cold condensation effects in mountains with the CliMoChem model for a group of substances with different volatility and persistence. The mountainous region is set up in a generic way by modifying the precipitation rate and annual temperature course in a northern temperate zone. The results illustrate substance-specific tendencies to exhibit a cold condensation. While strong effects are observed for alpha-hexachlorocyclohexane and PCB-28, the less volatile compounds mirex and PCB-180 are less susceptible to mountainous cold condensation. An analysis of the temporal trends in concentrations indicates that mountain ranges first act as cold condensers, but may eventually become secondary emitters. Limitations of the modeling approach used are discussed and an outlook on further steps of model development and application is given.

Altitude↗

PubMed2006

Effects of kraft pulp mill condensates on plasma testosterone levels in mummichog (Fundulus heteroclitus).

Past studies at a bleached kraft pulp mill located in Saint John, NB, Canada have shown that chemical recovery condensates significantly depress circulating and gonadal steroids in mummichog (Fundulus heteroclitus), an endemic fish species. In the present study, compounds were extracted from the condensates, and a toxicity identification evaluation (TIE) was conducted to characterize the hormonally active substances (HASs) in the condensates. Extracts were fractionated by high performance liquid chromatography (HPLC) and mummichog were exposed to the fractions in a 7-day bioassay. Plasma testosterone was measured for each sex following exposure. Responses in fish exposed to the whole extract at 1% v/v were not as pronounced as had been observed previously (female plasma testosterone was reduced by 16% in the current study compared to 75% previously). Dose-response experiments showed an exposure concentration of 4% v/v was required to elicit significant plasma steroid reductions. Despite these responses, individual condensate fractions actually increased steroid levels in mummichog, which suggests that multiple HASs may need to act synergistically or additively to elicit effects, and if separated, the compounds may have different hormonal activity. The HASs in question caused a reduction in male gonad size at 4% v/v, and have sex-dependent mechanisms of action (males were more responsive to exposure than females).

Animals↗

PubMed2005

Age-related calcium changes, oxyradical damage, caspase activation and nuclear condensation in hippocampal neurons in response to glutamate and beta-amyloid.

Neuronal degeneration increases with age in response to stressors, but the sub-cellular mechanism is unknown, partly because of previous difficulty in studying aged neurons in isolation. We studied the mechanism of enhanced neuronal susceptibility to glutamate and beta-amyloid in terms of condensed nuclei and other upstream events in hippocampal neurons cultured from old rats (24 months) compared to middle-age (10 months) and embryonic rats. Treatment of neurons from old animals with beta-amyloid (or glutamate) produced condensed nuclei 1.5x (2x) more frequently than middle-age and 3x (4x) more frequently than embryonic neurons. In addition to age-related baseline levels of caspase activation, neurons from old animals showed a 50% greater increase in caspase activation compared to middle-age and embryonic neurons. In contrast to glutamate treatment, beta-amyloid caused oxyradical damage as protein carbonyls increased 2-fold higher for old neurons than middle-age and 10-fold higher than embryonic neurons. Contrary to expectations, steady-state calcium levels for adult neurons did not increase in response to beta-amyloid. Overall, these results suggest that aged neurons have an inherent increased susceptibility to beta-amyloid toxicity through an early action of oxyradicals followed by caspase activation and nuclear condensation, a common pathway of apoptosis. Age-related glutamate toxicity involves other steps that lead to nuclear condensation, but neuron responses to calcium influx appear more important to cell death than the amount of influx.

Aging↗

PubMed2005

Evaluation of estrogenic activities of hydroxylated polycyclic aromatic hydrocarbons in cigarette smoke condensate.

Estrogenic activities of cigarette smoke condensates obtained from the extraction of particulate matters from mainstream and sidestream cigarette smoke with benzene/ethanol were evaluated by using a yeast two-hybrid assay system expressing human estrogen receptor alpha (hERalpha). To identify the constituents of the cigarette smoke condensate which are responsible for the estrogenic activity, the condensate was fractionated into eleven fractions by liquid-liquid extractions. Among these fractions, the neutral fractions of mainstream and sidestream smoke showed the strongest estrogen receptor-mediated activity by the yeast two-hybrid assay. Then the neutral fractions were fractionated by medium-pressure liquid chromatography with silica gel column. In the fractions that showed strong estrogenic activity, 2-hydroxyfluorene (2-OHFle), 2- and 3-hydroxyphenanthrene (2- and 3-OHPhe), 1-hydroxypyrene (1-OHPyr) and n-propyl-p-hydroxybenzoate (n-PHB) were identified by LC- and GC-MS and HPLC with fluorescence detection. 2-OHFle, 2-OHPhe and n-PHB exhibited estrogenic activity, whereas weak activity was observed with 3-OHPhe and 1-OHPyr. Several other hydroxylated polycyclic aromatic hydrocarbons having no activity were also identified. This is a first study to identify estrogenic hydroxylated PAHs in cigarette smoke condensate. The present findings points out the necessity for detailed investigation of exposure to aerosols containing apparently estrogenic compounds.

Chromatography, High Pressure Liquid↗

PubMed2006

Influence of DNA condensation state on transfection efficiency in DNA/polymer complexes: an AFM and DLS comparative study.

Atomic force microscopy (AFM) is used to describe the formation process of polymer/DNA complexes. Two main objectives of this research are presented. The first one is to apply AFM as an effective tool to analyse DNA molecules and different polycation/DNA complexes in order to evaluate their degree of condensation (size and shape). The other one is to search for a relationship between the condensation state of DNA and its transfection efficiency. In this study, linear methacrylate based polymers and globular SuperFect polymers are used in order to induce DNA condensation. Ternary complexes, composed of methacrylate based polymers and polyethylene glycol (PEG)-based copolymers, are also investigated. AFM allows us to confirm good condensation conditions and relate them (or not) to transfection efficiencies. These AFM results (obtained after drying in air) are compared with measurements deduced from Dynamic Light Scattering (DLS) experiments performed in water. This comparison allowed us to identify the structural modifications resulting from deposition on the mica surface.

Animals↗

PubMed2005

Control of VOCs emissions by condenser pre-treatment in a semiconductor fab.

The performance of a modified design of local condensers to pre-treat a variety of volatile organic compounds (VOCs) emitted from the stripping process of a semiconductor fab was tested in this study. The reaction temperature of the condensers was controlled at around 10 degrees C, it is relatively higher than the traditional condenser reaction temperature. Both VOCs and water vapors were condensed and formed liquid films. This resulted in an enhancement of the VOCs removals, especially for VOCs of high boiling points or solubility. This can help to prevent the follow up zeolite concentrator from damage. The performance of the integrated system of condenser/zeolite concentrator could, therefore, remain highly efficient for a longer operation time. Its annualized cost would also be lower than installing the zeolite concentrator only.

Air Pollution↗

PubMed2005

Exhaled nitric oxide levels in school children in relation to IgE sensitisation and window pane condensation.

BACKGROUND: A positive relation between exhaled nitric oxide (NO) levels and allergen exposure has been found in some studies whereas there is less information on how non-allergen environmental factors influences exhaled NO. OBJECTIVE: To study the relationship between exhaled NO levels in schoolchildren in relation to IgE sensitisation and allergenic and non-allergenic environmental factors. METHOD: This study comprised 374 schoolchildren (13-14 years of age) who performed exhaled NO-measurements and skin prick tests. Exposure to allergens, respiratory infections, environmental tobacco smoke and home window pane condensation, the latter an indicator of high humidity and poor ventilation was evaluated through questionnaires. RESULTS: In IgE-sensitised children sensitisation to pets was a more important determinant of exhaled NO than sensitisation to pollen. Higher NO levels were found in cat-sensitised children with a cat or other furred pets at home compared to cat-sensitised children without pets (geometric mean, 24.0 vs. 13.9 ppb, P=0.03). Significantly higher exhaled NO levels were found in non-sensitised children that reported having a cold (5.7 vs. 3.8 ppb, P<0.001) or lived in homes with window pane condensation (7.1 vs. 4.4 ppb, P=0.01) than in non-sensitised children without a cold and window pane condensation, respectively. These associations were not found in children that were sensitised to inhalation allergens. CONCLUSION: Allergen exposure seems to be the most important determinant for exhaled NO levels in IgE-sensitised children whereas in non-sensitised children NO levels were associated with respiratory infections and home window pane condensation.

Adolescent↗

PubMed2005

Root surface temperature rises during root canal obturation, in vitro, by the continuous wave of condensation technique using System B HeatSource.

OBJECTIVES: This in vitro study evaluated increases in root surface temperature during the continuous wave of condensation technique using a System B HeatSource. STUDY DESIGN: Forty-five extracted human teeth (15 maxillary central incisors, 15 mandibular central incisors, and 15 maxillary canines) were used. After root canal cleaning and shaping, the teeth were filled with the continuous wave of condensation technique using a System B HeatSource. Temperature changes on the whole mesial and vestibular outer surfaces of the roots were measured using an infrared thermal imaging camera. RESULTS: The results of this in vitro study showed that the use of the continuous wave of condensation technique to fill the maxillary central incisors and maxillary canines produced temperature rises below the critical level. In the mandibular central incisors the use of a System B HeatSource resulted in elevation of the root surface temperature by more than 10 degrees C. CONCLUSION: The continuous wave of condensation technique using the System B HeatSource produces temperature changes on the outer root surfaces, which, in the case of teeth with relatively thin dentinal walls, can reach relatively high values.

Body Temperature↗

PubMed1997

Management of condensation on a foldable acrylic intraocular lens after vitrectomy and fluid-air exchange.

PURPOSE: To describe the management of condensation on the posterior surface of a foldable acrylic intraocular lens during vitrectomy and fluid-air exchange. METHODS: A 70-year-old pseudophakic man with a foldable acrylic intraocular lens and open posterior capsule underwent vitrectomy and fluid-air exchange for repair of rhegmatogenous retinal detachment. RESULTS: During pars plana vitrectomy and fluid-air exchange, condensation immediately formed on the posterior surface of the foldable acrylic intraocular lens. This condensation, which prevented a view of the retina, was eliminated by wiping the posterior surface of the intraocular lens with a soft-tipped cannula. CONCLUSION: Although condensation may rapidly form on acrylic intraocular lenses during vitrectomy and fluid-air exchange, it can be managed readily by wiping with a soft-tipped cannula.

Aged↗

PubMed2000

A commentary on the screened-Oseen, counterion-condensation formalism of polyion electrophoresis.

The use of linear theory, in particular, counterion condensation (CC) theory, in describing electrophoresis of polyelectrolyte chains, is criticized on several grounds. First, there are problems with CC theory in describing the equilibrium distribution of ions around polyelectrolytes. Second, CC theory is used to treat ion relaxation in a linear theory with respect to the polyion charge despite the fact that ion relaxation arises as a consequence of nonlinear charge effects. This nonlinearity has been well established by several investigators over the last 70 years for spherical, cylindrical, and arbitrarily shaped model polyions. Third, current use of CC theory ignores the electrophoretic hindrance as well as the ion relaxation for condensed counterions and only includes such interactions for uncondensed counterions. Because most of the condensed counterions lie outside the shear surface of the polyion (in the example of DNA), the assumption of ion condensation is artificial and unphysical. Fourth, the singular solution, based on a screened Oseen tensor, currently used in the above mentioned theories is simply wrong and fails to account for the incompressibility of the solvent. The actual singular solution, which has long been available, is discussed. In conclusion, it is pointed out that numerical alternatives based on classic electrophoresis theory (J.T.G. Overbeek, Kolloid-Beih, 1943, 54:287-364) are now available.

Biopolymers↗

PubMed2001

Flexible polymer-induced condensation and bundle formation of DNA and F-actin filaments.

A simple semi-empirical theory is developed for the ionic strength dependence of the flexible polymer-induced condensation of semiflexible polyelectrolytes such as DNA and F-actin filaments. Critical concentrations of flexible polymer needed for condensation are calculated by comparing the free energies of inserting the semiflexible polyelectrolytes in a solution of flexible polymers, respectively, in their free state, and in their condensed state. Predictions of the theory are compared to experimental data on the condensation of DNA and F-actin filaments induced by the flexible polymer poly(ethylene oxide). The theory also predicts that reentrant decollapse is possible at low ionic strength and high concentrations of flexible polymer, as observed for DNA.

Actins↗

PubMed2002

Entrapment and condensation of DNA in neutral reverse micelles.

DNA condensation and compaction is induced by a variety of condensing agents such as polycations. The present study analyzed the structure of plasmid DNA (DNA) in the small inner space of reverse micelles formed from nonionic surfactants (isotropic phase). Spectroscopic studies indicated that DNA was dissolved in an organic solvent in the presence of a neutral detergent. Fluorescent quenching of ethidium bromide and of rhodamine covalently attached to DNA suggested that the DNA within neutral, reverse micelles was condensed. Circular dichroism indicated that the DNA structure was C form (member of B family) and not the dehydrated A form. Concordantly, NMR experiments indicated that the reverse micelles contained a pool of free water, even at a ratio of water to surfactant (Wo) of 3.75. Electron microscopic analysis also indicated that the DNA was in a ring-like structure, probably toroids. Atomic force microscopic images also revealed small, compact particles after the condensed DNA structures were preserved using an innovative cross-linking strategy. In the lamellar phase, the DNA was configured in long strands that were 20 nm in diameter. Interestingly, such DNA structures, reminiscent of "nanowires," have apparently not been previously observed.

Circular Dichroism↗