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PubMed1970

Comparative carcinogenicity for mouse-skin of smoke condensates prepared from cigarettes made from the same tobacco cured by two processes.

Bright tobacco grown in Mexico was either flue-cured and redried (FC) or air-cured and bulk-fermented (AC). Both FC and AC were made into cigarettes standardized for draw resistance. FC and AC cigarettes were smoked under similar conditions in a smoking machine (one 2-second 25 ml. puff per minute down to a 20 mm. butt length). Condensates were kept at 0-4° C. until applied to the skin of mice.Three groups of 400 female Swiss mice were treated as follows: Group 1- thrice weekly application of 60 mg. FC in 0.25 ml. acetone to the clipped dorsal skin: Group 2- similar treatment with AC; Group 3-thrice weekly application of 0.25 ml. acetone only.Chemical analysis of the 2 tobaccos and 2 condensates revealed only small differences in composition and it is noteworthy that the concentration of reducing sugars was almost as high as in the AC tobacco as in the FC tobacco.The risk of development of skin tumours, particularly malignant skin tumours, was higher in FC-treated mice than in AC-treated mice (p < 0.01), but the difference may have been due to the use of equal weights of condensates rather than the use of extracts from equal numbers of cigarettes, since the AC cigarettes produced more condensate. The rates of detection of pulmonary tumours also varied between groups (p < 0.01) but this does not necessarily imply that the incidence rates of pulmonary tumours varied. There was no evidence that the detection or incidence rates of any other neoplasms, including malignant lymphoma, were affected by treatment with either of the condensates.

Animals↗

PubMed2006

Bose-Einstein condensation of quasi-equilibrium magnons at room temperature under pumping.

Bose-Einstein condensation is one of the most fascinating phenomena predicted by quantum mechanics. It involves the formation of a collective quantum state composed of identical particles with integer angular momentum (bosons), if the particle density exceeds a critical value. To achieve Bose-Einstein condensation, one can either decrease the temperature or increase the density of bosons. It has been predicted that a quasi-equilibrium system of bosons could undergo Bose-Einstein condensation even at relatively high temperatures, if the flow rate of energy pumped into the system exceeds a critical value. Here we report the observation of Bose-Einstein condensation in a gas of magnons at room temperature. Magnons are the quanta of magnetic excitations in a magnetically ordered ensemble of magnetic moments. In thermal equilibrium, they can be described by Bose-Einstein statistics with zero chemical potential and a temperature-dependent density. In the experiments presented here, we show that by using a technique of microwave pumping it is possible to excite additional magnons and to create a gas of quasi-equilibrium magnons with a non-zero chemical potential. With increasing pumping intensity, the chemical potential reaches the energy of the lowest magnon state, and a Bose condensate of magnons is formed.

Journal Article↗

PubMed2006

Dynamic state of DNA topology is essential for genome condensation in bacteria.

In bacteria, Dps is one of the critical proteins to build up a condensed nucleoid in response to the environmental stresses. In this study, we found that the expression of Dps and the nucleoid condensation was not simply correlated in Escherichia coli, and that Fis, which is an E. coli (gamma-Proteobacteria)-specific nucleoid protein, interfered with the Dps-dependent nucleoid condensation. Atomic force microscopy and Northern blot analyses indicated that the inhibitory effect of Fis was due to the repression of the expression of Topoismerase I (Topo I) and DNA gyrase. In the Deltafis strain, both topA and gyrA/B genes were found to be upregulated. Overexpression of Topo I and DNA gyrase enhanced the nucleoid condensation in the presence of Dps. DNA-topology assays using the cell extract showed that the extracts from the Deltafis and Topo I-/DNA gyrase-overexpressing strains, but not the wild-type extract, shifted the population toward relaxed forms. These results indicate that the topology of DNA is dynamically transmutable and that the topology control is important for Dps-induced nucleoid condensation.

Bacterial Outer Membrane Proteins↗

PubMed2002

Cigarette smoke condensate aggravates renal injury in the renal ablation model.

BACKGROUND: Cigarette smoking increases the risk of progression of diabetic and non-diabetic renal diseases. The mechanisms underlying the adverse effects of smoking are largely unknown. We examined the subtotally nephrectomized rat (i) to investigate whether components of cigarette smoke dissolved in acetone (cigarette smoke condensate) aggravate structural renal damage and (ii) to establish whether this provides an animal model that can be used to investigate potential pathomechanisms of cigarette smoke-induced renal damage. Since nicotine activates the sympathetic nerve system in humans, we investigated whether interference with this system modulates the effects of cigarette smoke condensate on the damaged kidney. METHODS: One group of Sprague-Dawley rats was subtotally nephrectomized (SNX). Acetone (SNX + solvent) or cigarette smoke condensate (SNX + cigarette) was applied daily to the oral mucosa. Another group of Sprague-Dawley rats was sham-operated and received the same treatments (sham + solvent, sham + cigarette). To investigate whether increased activity of the sympathetic nerve system is involved, the remnant kidney was denervated by microsurgical technique in one SNX + cigarette group. The control group for this intervention was a solvent-treated SNX group with denervated remnant kidney. Blood pressure (BP) was measured weekly by tail plethysmography. The experiment was terminated after 12 weeks. Structural renal damage was assessed by morphometric techniques (indices of glomerulosclerosis, tubulointerstitial and vascular damage) and urinary albumin and endothelin-1 excretion were measured. RESULTS: Indices of structural renal damage were increased in all SNX-groups. Treatment with cigarette smoke condensate further increased the indices of glomerulosclerosis and tubulointerstitial damage in SNX, but not sham-operated rats. This increase was completely prevented by renal denervation. No differences in systemic blood pressure were observed in the different SNX groups. Urinary albumin excretion went in parallel with the indices of glomerulosclerosis and tubulointerstitial damage and urinary endothelin-1 excretion was significantly increased in SNX + cigarette animals. CONCLUSION: These findings document that acetone soluble components in cigarette smoke aggravate glomerulosclerosis and tubulointerstitial damage in the renal ablation model. Renal injury induced by cigarette smoke condensate in this model is reversed by renal denervation. We conclude that cigarette smoke-induced renal damage is due, at least in part, to activation of the sympathetic nerve system.

Albuminuria↗

PubMed1999

Increased content of thiobarbituric acid-reactive substances and hydrogen peroxide in the expired breath condensate of patients with stable chronic obstructive pulmonary disease: no significant effect of cigarette smoking.

The imbalance between oxidants and antioxidants is known to play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cigarette smoking is the most frequent factor responsible for development of COPD by leading to oxidant overload in the lower airways, due to presence of its own oxidants and to recruitment and activation of pulmonary phagocytes. We aimed to determine whether (1) patients with stable COPD have higher thiobarbituric acid-reactive substances (TBARs, an end-product of lipid peroxidation) and H2O2 levels in expired breath condensate than healthy subjects who have never smoked; (2) COPD subjects who are current smokers exhale more TBARs and H2O2 than COPD ex-smokers and those who have never smoked; and (3) concentration of TBARs correlates with H2O2 levels in the breath condensate of COPD patients. The TBAR and H2O2 content in expired breath condensate of 17 healthy nonsmoking subjects and 44 patients (11 current smokers, 20 ex-smokers and 13 who had never smoked) with stable COPD [forced expiratory volume in 1 s (FEV1) 63.3 +/- 16.3% and FEV1 reversibility 5.2 +/- 4.3% predicted value] was measured spectrofluorimetrically by the thiobarbituric acid and homovanillic acid methods, respectively. The mean concentrations of TBARs and H2O2 in the expired breath condensate of COPD subjects were 12 (0.48-0.86 microM vs. 0.04 +/- 0.14 microM; P < 0.05) and 10 times (0.48 +/- 0.67 microM vs. 0.05 +/- 0.07 microM; P < 0.005) higher than in healthy controls. Current smokers with COPD did not exhale more H2O2 than COPD ex-smokers and those who had never smoked. TBARs levels shared only a tendency to be higher in the breath condensate of smoking COPD subjects than in that of ex-smokers (0.92 +/- 1.49 microM vs. 0.35 +/- 0.44 microM) and of COPD subjects who had never smoked (0.92 +/- 1.49 microM vs. 0.30 +/- 0.53 microM). No correlation was found between TBAR and H2O2 levels in the whole COPD group. These variables did not correlate with cigarette smoking status and the time from smoking cessation. Subjects with stable COPD exhibit increased lipid peroxidation and H2O2 generation in the airways. Current cigarette smoking does not distinguish COPD subjects with respect to TBARs and H2O2 exhalation.

Antioxidants↗

PubMed2000

Inhaled glucocorticosteroids decrease hydrogen peroxide level in expired air condensate in asthmatic patients.

H2O2 is elevated in the exhaled air condensate in several inflammatory disorders of the lung, including bronchial asthma, and thus may reflect inflammatory processes in the airways. Exhaled H2O2 may be used to guide the anti-inflammatory treatment of patients with asthma. Therefore in this study we analysed the effect of inhaled glucocorticosteroid beclomethasone for 4 weeks on H2O2 level in the exhaled air condensate. Seventeen asthmatics and 10 healthy subjects were included to the study. Eleven patients were given inhaled beclomethasone and six were given placebo (3M Health Care). In all patients pulmonary function tests were performed. H2O2 in the expired air condensate was measured spectrofluorimetically (homovanillic acid method). Inhaled beclomethasone significantly decreased H2O2 in the expired air condensate in the active-treatment group, with a fall from baseline on day 1 which remained on day 43 (follow-up) (P<0.05). Exhaled H2O2 in the active-treatment group was significantly lower than that in placebo group (P<0.05). A negative correlation between H2O2 and forced expiratory volume in 1 sec (FEV1) on day 29 was observed. The decrease in exhaled H2O2 in the active-treatment group was accompanied by an improvement in pulmonary function tests results. Inhaled glucocorticoids reduce the level of H2O2 in the expired air condensate of asthmatic patients over a 4-week period and this may reflect their anti-inflammatory activity in lung diseases.

Administration, Inhalation↗

PubMed2002

Exhaled breath condensate and serum levels of hepatocyte growth factor in pneumonia.

Hepatocyte growth factor (HGF) is a protein produced by mesenchymal cells in many organs, which can stimulate epithelial growth. An enhanced production and concentration of HGF is observed after injuries. The lung is one of the major sources of HGF. By cooling exhaled air, a condensate is formed containing molecules from bronchi and alveoli. In order to investigate HGF-concentration and time course in pneumonia, paired serum and exhaled breath condensate was collected from 10 patients with pneumonia, 10 patients with non-respiratory infections and 11 healthy controls. The concentration of HGF was measured by an immunoassay kit. In the acute phase HGF-levels in breath condensate and serum were significantly higher in the patients with pneumonia compared to the control groups. Similar concentrations in breath condensate were seen in healthy controls and in patients with non-respiratory infections. In the patients with pneumonia a decrease in serum HGF was seen already after 4-7 days while HGF values in breath condensate remained elevated even after 4-6 weeks. These results might imply local product on of HGF in the lungs and a long repair and healing process after pneumonia.

Adult↗

PubMed2005

Condensation of a vapor bubble in submicrometer container.

Condensation of a spherically symmetric submicrometer size vapor bubble is studied using diffuse interface hydrodynamic model supplemented by the van der Waals equation of state with parameters characteristic for argon. The bubble, surrounded by liquid, is held in a container of constant volume with temperature of the wall kept fixed. The condensation is triggered by a sudden rise of the wall temperature. We find that in the same container and subjected to a similar increase of the wall temperature the condensation process is totally different from the opposite process of droplet evaporation. In particular, the rapid change of the wall temperature excites the wave, which hits the interface and compresses the bubble, leading to a considerable increase of the temperature inside. The condensation of the submicrometer size bubble takes tens of nanoseconds, whereas evaporation of the same size droplet lasts roughly 50 times longer. In contrast to evaporation the condensation process is hardly quasistationary.

Journal Article↗

PubMed2005

Nucleoplasmin regulates chromatin condensation during apoptosis.

Although chromatin condensation is one of the hallmarks of apoptosis, its relationship with DNA fragmentation has been controversial. We show here that apoptotic chromatin condensation is regulated by nucleoplasmin, a protein that decondenses sperm chromatin during male pronuclear assembly. In Xenopus egg extracts, nucleoplasmin is tyrosine-dephosphorylated during apoptosis. This dephosphorylation inactivates the chromatin decondensation activity of nucleoplasmin and leads to its exclusion from the chromatin. Inhibition of tyrosine dephosphorylation prevents apoptotic chromatin condensation but not DNA fragmentation. Studies with mutant proteins indicate that dephosphorylation of nucleoplasmin at Tyr-124 regulates chromatin condensation through changes in the interaction of nucleoplasmin with chromatin and the loss of its chromatin decondensation activity. These results show that chromatin condensation and DNA fragmentation are independent processes.

Animals↗

PubMed2005

Effect of condensate formation on long-distance radical cation migration in DNA.

Long-distance radical cation transport was studied in DNA condensates. Linearized pUC19 plasmid was ligated to an oligomer containing a covalently linked anthraquinone group and six regularly spaced GG steps, which serve as traps for the migrating radical cation. Treatment of the linear, ligated plasmid with spermidine results in formation of condensates that were detected by light scattering and observed by transmission electron microscopy. Irradiation of the anthraquinone group in the condensate causes long-distance charge migration, which is detected by reaction at the remote guanines. The efficiency of charge migration in the condensate is significantly less than it is for the corresponding oligomer in solution. This result is attributed to a lower mobility for the migrating radical cation in the condensate, which is caused by inhibited formation of charge-transfer-effective states.

Anthraquinones↗

PubMed2000

DNA delivery by phage as a strategy for encapsulating toroidal condensates of arbitrary size into liposomes.

We report a strategy for encapsulating and condensing DNA. When T5 phage binds to its membrane protein receptor, FhuA, its double stranded DNA (120,000 bp) is progressively released base pair after base pair in the surrounding medium. Using cryoelectron microscopy, we have visualized the structures formed after T5 phage DNA is released into neutral unilamellar proteoliposomes reconstituted with the receptor FhuA. In the presence of spermine, toroidal condensates of circumferentially wrapped DNA were formed. Most significantly, the sizes of these toroids were shown to vary, from 90 to 200 nm in their outer diameters, depending on the number of DNA stands transferred. We have also analyzed T5 DNA release in bulk solution containing the detergent-solubilized FhuA receptor. After DNA release in a spermine containing solution, huge DNA condensates with a diameter of about 300 nm were formed containing the DNAs from as many as 10-20 capsids. At alkaline pH, the condensates appeared as large hollow cylinders with a diameter of 200 nm and a height of 100-200 nm. Overall, the striking feature of our experiments is that, because of the progressive release of DNA from the phage capsid, the mechanism of toroid formation is fundamentally different from that in the classical studies in which highly dilute, "naked" DNA is condensed by direct addition of polyvalent cations; as a consequence, our method leads to toroids of arbitrary size.

Bacteriophages↗

PubMed2003

Controlling the size of nanoscale toroidal DNA condensates with static curvature and ionic strength.

The process of DNA condensation into nanometer-scale particles has direct relevance to several fields, including cell biology, virology, and gene delivery for therapeutic purposes. DNA condensation has also attracted the attention of polymer physicists, as the collapse of DNA molecules from solution into well defined particles represents an exquisite example of a polymer phase transition. Here we present a quantitative study of DNA toroids formed by condensation of 3 kb DNA with hexammine cobalt (III). The presence or absence of static loops within this DNA molecule demonstrates the effect of nucleation loop size on toroid dimensions and that nucleation is principally decoupled from toroid growth. A comparison of DNA condensates formed at low ionic strength with those formed in the presence of additional salts (NaCl or MgCl2) shows that toroid thickness is a salt-dependant phenomenon. Together, these results have allowed the development of models for DNA toroid formation in which the size of the nucleation loop directly influences the diameter of the fully formed toroid, whereas solution conditions govern toroid thickness. The data presented illustrate the potential that exists for controlling DNA toroid dimensions. Furthermore, this study provides a set of data that should prove useful as a test for theoretical models of DNA condensation.

Cobalt↗

PubMed2000

Condensed complexes, rafts, and the chemical activity of cholesterol in membranes.

Epifluorescence microscopy studies of mixtures of phospholipids and cholesterol at the air-water interface often exhibit coexisting liquid phases. The properties of these liquids point to the formation of "condensed complexes" between cholesterol and certain phospholipids, such as sphingomyelin. It is found that monolayers that form complexes can incorporate a low concentration of a ganglioside G(M1). This glycolipid is visualized by using a fluorescently labeled B subunit of cholera toxin. Three coexisting liquid phases are found by using this probe together with a fluorescent phospholipid probe. The three liquid phases are identified as a phospholipid-rich phase, a cholesterol-rich phase, and a condensed complex-rich phase. The cholera toxin B labeled ganglioside G(M1) is found exclusively in the condensed complex-rich phase. Condensed complexes are likely present in animal cell membranes, where they should facilitate the formation of specialized domains such as rafts. Condensed complexes also have a major effect in determining the chemical activity of cholesterol. It is suggested that this chemical activity plays an essential role in the regulation of cholesterol biosynthesis. Gradients in the chemical activity of cholesterol should likewise govern the rates and direction of intracellular intermembrane cholesterol transport.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1974

Analysis of interphase chromosome damage by means of premature chromosome condensation after X- and ultraviolet-irradiation.

Sendai virus-mediated fusion between mitotic and interphase mammalian cells causes the rapid condensation of the interphase chromosomes into distinct structures, a process termed premature chromosome condensation. This phenomenon has been used to assess the immediate action of x-rays and ultraviolet light on the chromosomes of HeLa cells irradiated in the G1 phase of the life cycle. X-irradiation produces fragmented chromosomes; but even the most finely chopped fragments retain the condensed morphology characteristic of the premature chromosome condensation of unirradiated G1 cells. For doses up to about 1800 rads, the increase in the number of fragments is linearly related to the dose. One mean lethal dose (about 100 rads) yields a net increase of 10-15 fragments per G1 cell, which is considerably larger than previous estimates based on scoring of mitotic chromosomes. Incubation of irradiated cells produces a rapid (within 2 hr) reduction in the number of fragments, indicative of a rejoining process. The decrease in the number of pieces is not accompanied by unscheduled DNA synthesis detectable by radioautography. G1 chromosomes of cells irradiated with UV light in G1 phase are not appreciably fragmented but are elongated and attenuated so that they resemble the premature-chromosome-condensation chromosomes of unirradiated S-phase cells. Both the degree of "S-like" character attained by the G1 chromosomes in a cell and the percentage of the cell population displaying the G1 --> S transition increase with the dose and incubation time after irradiation. Thus, in contrast to the immediate manifestation of damage from x-rays, the maximum induction of the "S-like" state does not occur until about 2 hr after irradiation. The "S-like" chromosomes are capable of unscheduled DNA synthesis. We suggest that the difference in chromosome morphology found after UV- and x-irradiation underlies the reason why the former, but not the latter, induces unscheduled DNA synthesis in G1 cells.

Cell Fusion↗

PubMed1984

Condensation of nucleic acids by intercalating aromatic cations.

Certain intercalating aromatic cations, such as the fluorochrome acridine orange or the antitumor drug Mitoxantrone, induce condensation of nucleic acids in solutions. The appearance of the condensed form during titration of nucleic acids with these intercalating ligands can be quantitatively monitored by light scatter measurements. The resulting highly reproducible light scatter transition curves are typical of the cooperative processes, and the transitions occur at different critical concentrations of the ligands depending upon both the ligand itself and the primary structure (base and sugar composition) and the secondary structure (single- or double-stranded) of the nucleic acids. The mechanism of condensation of nucleic acids by intercalating cationic ligands is discussed in light of the model of interactions occurring between certain intercalators and single-stranded nucleic acids and compared with the condensation induced by polyvalent "simple" cations such as Co3+ or spermine4+. The described phenomenon can have an application in analytical and preparative biochemistry for characterization of the primary and secondary structure of nucleic acids and for separation of the compounds. The possibility that the condensation plays a role in mutagenic and pharmacological effects of aromatic cations is considered.

Acridine Orange↗

PubMed2001

The reversible condensation and expansion of the rotavirus genome.

Understanding the structural organization of the genome is particularly relevant in segmented double-stranded RNA viruses, which exhibit endogenous transcription activity. These viruses are molecular machines capable of repeated cycles of transcription within the intact capsid. Rotavirus, a major cause of infantile gastroenteritis, is a prototypical segmented double-stranded RNA virus. From our three-dimensional structural analyses of rotavirus examined under various chemical conditions using electron cryomicroscopy, we show here that the viral genome exhibits a remarkable conformational flexibility by reversibly changing its packaging density. In the presence of ammonium ions at high pH, the genome condenses to a radius of approximately 180 A from approximately 220 A. Upon returning to physiological conditions, the genome re-expands and fully maintains its transcriptional properties. These studies provide further insights into the genome organization and suggest that the observed isometric and concentric nature of the condensation is due to strong interactions between the genome core and the transcription enzymes anchored to the capsid inner surface. The ability of the genome to condense beyond what is normally observed in the native virus indicates that the negative charges on the RNA in the native state may be only partially neutralized. Partial neutralization may be required to maintain appropriate interstrand spacing for templates to move around the enzyme complexes during transcription. Genome condensation was not observed either with increased cation concentrations at normal pH or at high pH without ammonium ions. This finding indicates that the observed genome condensation is a synergistic effect of hydroxyl and ammonium ions involving disruption of protein-RNA interactions that perhaps facilitate further charge neutralization and consequent reduction in the interstrand spacing.

Animals↗

PubMed2000

The core histone N termini function independently of linker histones during chromatin condensation.

The relationships between the core histone N termini and linker histones during chromatin assembly and salt-dependent chromatin condensation were investigated using defined chromatin model systems reconstituted from tandemly repeated 5 S rDNA, histone H5, and either native "intact" core histone octamers or "tailless" histone octamers lacking their N-terminal domains. Nuclease digestion and sedimentation studies indicate that H5 binding and the resulting constraint of entering and exiting nucleosomal DNA occur to the same extent in both tailless and intact chromatin arrays. However, despite possessing a normal chromatosomal structure, tailless chromatin arrays can neither condense into extensively folded structures nor cooperatively oligomerize in MgCl(2). Tailless nucleosomal arrays lacking linker histones also are unable to either fold extensively or oligomerize, demonstrating that the core histone N termini perform the same functions during salt-dependent condensation regardless of whether linker histones are components of the array. Our results further indicate that disruption of core histone N termini function in vitro allows a linker histone-containing chromatin fiber to exist in a decondensed state under conditions that normally would promote extensive fiber condensation. These findings have key implications for both the mechanism of chromatin condensation, and the regulation of genomic function by chromatin.

Chromatin↗

PubMed2005

Versican/PG-M regulates chondrogenesis as an extracellular matrix molecule crucial for mesenchymal condensation.

Mesenchymal cell condensation is an essential step for cartilage development. Versican/PG-M, a large chondroitin sulfate proteoglycan, is one of the major molecules expressed in the extracellular matrix during condensation. However, its role, especially as an environment for cells being condensed, has not been elucidated. Here we showed several lines of evidence for essential roles of versican/PG-M in chondrogenic condensation using a new chondrocytic cell line, N1511. Chondrogenic stimuli (treatment with parathyroid hormone, dexamethasone, 10% serum) induced a marked increase in the transcription and protein synthesis of versican/PG-M. Stable antisense clones for versican/PG-M, depending on suppression of the expression of versican/PG-M, showed different capacities for chondrogenesis, as indicated by the expression and deposition of aggrecan, a major chondrocytic cell product. The cells in the early stages of the culture only expressed V0 and V1 forms, having more chondroitin sulfate chains among the four variants of versican/PG-M, and treatment of those cells with chondroitinase ABC suppressed subsequent chondrogenesis. Furthermore, treatment with beta-xyloside, an artificial chain initiator of chondroitin sulfate synthesis to consequently inhibit the synthesis on the core proteins, suppressed chondrogenesis. In addition, forced expression of the variant V3, which has no chondroitin sulfate chain, disrupted the deposition and organization of native versican/PG-M (V0/V1) and other extracellular matrix molecules known to be expressed during the mesenchymal condensation and resulted in the inhibition of subsequent chondrogenesis. These results suggest that versican/PG-M is involved in positively regulating the formation of the mesenchymal matrix and the onset of chondrocyte differentiation through the attached chondroitin sulfate chains.

Aggrecans↗