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PubMed1999

Involvement of Frzb-1 in mesenchymal condensation and cartilage differentiation in the chick limb bud.

In developing limb bud, mesenchymal cells form cellular aggregates called "mesenchymal condensations". These condensations show the prepattern of skeletal elements of the limb prior to cartilage differentiation. Roles of various signaling molecules in chondrogenesis in the limb bud have been reported. One group of signaling factors includes the Wnt proteins, which have been shown to have an inhibitory effect on chondrogenesis in the limb bud. Therefore, regulation of Wnt activity may be important in regulating cartilage differentiation. Here we show that Frzb-1, which encodes a secreted frizzled-related protein that can bind to Wnt proteins and can antagonize the activity of some Wnts, is expressed in the developing limb bud. At early stages of limb development, Frzb-1 is expressed in the ventral core mesenchyme of the limb bud, and later Frzb-1 expression becomes restricted to the central core region where mesenchymal condensations occur. At these stages, a chondrogenic marker gene, aggrecan, is not yet expressed. As limb development proceeds, expression of Frzb-1 is detected in cartilage primordial cells, although ultimately Frzb-1 expression is down-regulated. Similar results were obtained in the recombinant limb bud, which was constructed from dissociated and re-aggregated mesenchymal cells and an ectodermal jacket with the apical ectodermal ridge. In addition, Frzb-1 expression preceded aggrecan expression in micromass cultures. These results suggest that Frzb-1 has a role in condensation formation and cartilage differentiation by regulating Wnt activity in the limb bud.

Aggrecans↗

PubMed2001

Linker DNA destabilizes condensed chromatin.

The contribution of the linker region to maintenance of condensed chromatin was examined in two model systems, namely sea urchin sperm nuclei and chicken red blood cell nuclei. Linkerless nuclei, prepared by extensive digestion with micrococcal nuclease, were compared with Native nuclei using several assays, including microscopic appearance, nuclear turbidity, salt stability, and trypsin resistance. Chromatin in the Linkerless nuclei was highly condensed, resembling pyknotic chromatin in apoptotic cells. Linkerless nuclei were more stable in low ionic strength buffers and more resistant to trypsin than Native nuclei. Analysis of histones from the trypsinized nuclei by polyacrylamide gel electrophoresis showed that specific histone H1, H2B, and H3 tail regions stabilized linker DNA in condensed nuclei. Thermal denaturation of soluble chromatin preparations from differentially trypsinized sperm nuclei demonstrated that the N-terminal regions of histones Sp H1, Sp H2B, and H3 bind tightly to linker DNA, causing it to denature at a high temperature. We conclude that linker DNA exerts a disruptive force on condensed chromatin structure which is counteracted by binding of specific histone tail regions to the linker DNA. The inherent instability of the linker region may be significant in all eukaryotic chromatins and may promote gene activation in living cells.

Animals↗

PubMed2001

Assays for acetaldehyde-derived adducts in blood proteins based on antibodies against acetaldehyde/lipoprotein condensates.

BACKGROUND: Acetaldehyde-derived protein condensates (adducts) have been suggested as promising biological markers of alcohol abuse because they represent actual metabolites of ethanol. However, the detection of such condensates in vivo has been hampered by a lack of sensitive and specific methods. METHODS: To develop new approaches for the detection of acetaldehyde adducts, we have raised antibodies against condensates with acetaldehyde and lipoproteins, which have previously been shown to be readily modified by acetaldehyde in vitro. The characteristics of these antibodies were compared with those raised against bovine serum albumin/acetaldehyde adduct and against other types of lipoprotein modifications, as induced by malondialdehyde, oxidation, and acetylation. RESULTS: The antibodies raised against low-density lipoprotein (LDL)/acetaldehyde, very low density lipoprotein (VLDL)/acetaldehyde, and bovine serum albumin/acetaldehyde all reacted with protein adducts generated at physiologically relevant concentrations of acetaldehyde in vitro, whereas the antibodies raised against malondialdehyde/LDL, oxidized LDL, or acetylated LDL were not found to cross-react with the acetaldehyde-derived adducts. In assays for acetaldehyde adducts from erythrocyte and serum proteins of patients with excessive ethanol consumption (n = 32) and healthy control individuals (n = 22), the antibody prepared against the acetaldehyde/VLDL condensate was found to provide the most effective detection of acetaldehyde adducts in vivo. CONCLUSIONS: Current data indicate that acetaldehyde generates immunogenic adducts with lipoproteins in vivo. Antibodies raised against the VLDL/acetaldehyde may provide a basis for new diagnostic assays to examine excessive alcohol consumption.

Acetaldehyde↗

PubMed1999

An advance in condensable composites.

With the constant advance of technology and the public's increasing awareness of esthetically pleasing restorations, alternatives for amalgam and early composite materials have been brought to the forefront of dentistry. Condensable composites offer characteristics that distinguish them from their traditional hybrid counterparts: decreased wear, packability, and bulk curing with less polymerization shrinkage. Prodigy Condensable expands the first generation of condensables by altering its resin phase to make the material more packable. Through increased filler content and methacryoyloxyethlpolycaprolactonephosphate and rheological control additives, this second-generation condensable composite possesses strength and ease of use comparable to and even exceeding amalgam while demonstrating superior esthetics for all posterior restorations.

Amides↗

PubMed2002

Fluorescence correlation spectroscopy (FCS) as a tool to study DNA condensation with hexadecyltrimethylammonium bromide (HTAB).

The presented data show that the FCS technique can be used to detect the DNA condensation process induced with the cationic compound hexadecyltrimethylammonium bromide (HTAB). We have shown that HTAB induces plasmid condensation upon interaction with it. Condensation can be considered to be complete when the diffusion constant reaches its maximum. The HTAB induced increase in diffusion time does not correlate well with the changes observed when count rate and particle number are considered. This observation contradicts data published for another cationic agent, spermine. This apparent discrepancy proves that the mechanisms of interaction between these compounds and DNA are different. Consequently, the different characters of the plots of count rate, diffusion time, and particle number versus condensing agent concentration can be a source of additional information about the nature of cationic compound-DNA interaction.

Binding, Competitive↗

PubMed1999

[Effects of cooking oil fume condensate on cellular immunity and immunosurveillance in mice].

Rapeseed oil fume, soyabean oil fume and salad oil fume condensate were injected respectively to female Kunming mice. The results showed that, compared to control group, in mice exposed to low level of rapeseed oil fume condensate, the delayed hypersensitivity responses were inhibited, while in mice exposed to high level of that, the delayed hypersensitivity responses and the NK cells activity were inhibited. In mice exposed to high level of soyabean oil fume condensate the delayed hypersensitivity responses, the NK cells activity and CaM activity were inhibited. The results of these parameters were all statistically significantly different from those in control mice. In mice exposed to low level of salad oil fume condensation, the delayed hypersensitivity responses and the NK cells activity were significantly inhibited. The results indicated that cooking oil fume could affect immune system of animals.

Air Pollutants↗

PubMed2003

The importance of exhaled air condensate in assessing the oxidant-antioxidant system in patients with chronic obstructive pulmonary disease.

The aim of this study was to investigate the relationship between selected lipid peroxidation products as markers of oxidative stress and antioxidant defense capacity in exhaled air condensate in comparison to blood and COPD severity. We detected that the increase of lipids peroxidation products in exhaled air condensate (less in blood) was accompanied by the reduction of total antioxidant capacity (antiradical activity and ceruloplasmin) according to the severity of COPD. Thus, the level of malondialdehyde significantly increased both in blood and exhaled air condensate in COPD1,2,3 (by 24%, 86%, 100% and 58%, 92%, 2,3 times respectively). Antiradical activity level was significantly decreased both in blood and exhaled air condensate in patients with COPD2,3 by 24%, 51% and 23.31% respectively. The results of this study clearly demonstrated the imbalance in oxidant-antioxidant system in advanced COPD.

Adult↗

PubMed1994

[Study on the apical sealability of warm lateral condensation techniques]

An apical leakage test and a visible light spectrophotmetric analysis were performed to compare the apical sealability of warm lateral condensation and conventional lateral condensation techniques.The results showed that warm lateral with sealer delivered best sealability.It was superior to warm lateral without sealer(P<0.05) and conventional lateral condensation technique(P<0.01).Because of its inconvenient operation causing by native-made putta-percha,it is difficult to use warm lateral condensation technique widely in our country.

Journal Article↗

PubMed2005

Recent advances in heterocycle generation using the efficient Ugi multiple-component condensation reaction.

The current trend of rising research spending and falling numbers of novel chemical entities continues to drive efforts aimed at increasing efficiency in the drug discovery process. Strategic issues, such as assigning resources to poorly validated targets have been implicated in the declining productivity of recent years. Tactical approaches employed to improve this situation include attempts to speed the discovery process toward decision points in a timely manner. Accelerating the optimization of high-throughput screening hits is a goal in streamlining the discovery process, and the use of multiple-component condensation (MCC) reactions have proved useful toward this end. MCC reactions are powerful and efficient tools for the generation of diverse compound sets. Collections of compounds can be synthesized with all of the required diversity elements included in a single synthetic step. One of the most widely investigated MCC reactions is the Ugi four-component condensation. This review highlights disclosures of the Ugi reaction published over the past two years (2003 to 2005) in three areas: (i) Ugi reaction in conjunction with post-condensation cyclization; (ii) bifunctional condensations leading to heterocyclic cores; and (iii) general findings relating to linear products or interesting improvements in the basic Ugi reaction.

Automation↗

PubMed1991

Activation of amino-alpha-carboline, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and a copper phthalocyanine cellulose extract of cigarette smoke condensate by cytochrome P-450 enzymes in rat and human liver microsomes.

The ability of cigarette smoke condensate to induce a genotoxic response has been measured in liver microsomal and reconstituted monooxygenase systems containing rat and human cytochrome P-450 (P-450) enzymes, as determined by umu gene expression in Salmonella typhimurium TA1535/pSK1002. The reactivities of amino-alpha-carboline and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), two compounds known to be present at considerable levels in cigarette smoke condensate, were also determined and compared with regard to genotoxicity. Amino-alpha-carboline and PhIP are activated principally by P-450 1A2 enzymes in human and rat liver microsomes: (a) activation of both compounds was catalyzed efficiently by liver microsomes prepared from rats treated with 5,6-benzoflavone, isosafrole, or the commercial polychlorinated biphenyl mixture Aroclor 1254, and the activities could be considerably inhibited by antibodies raised against P-450 1A1 or 1A2; (b) the rates of activation of these compounds were correlated with the amount of human P-450 1A2 and of phenacetin O-deethylation activity in different human liver microsomal preparations, and these activities were inhibited by anti-P-450 1A2; (c) reconstituted enzyme systems containing P-450 1A enzymes isolated from rats and humans showed the highest rates of activation of amino-alpha-carboline and PhIP. In rat liver microsomes PhIP may also be activated by P-450 3A enzymes; activity was induced in rats treated with pregnenolone 16 alpha-carbonitrile and was inhibited by anti-human P-450 3A4. However, in humans the contribution of P-450 3A enzymes could be excluded as judged by the very low effects of anti-P-450 3A4 on the microsomal activities and poor correlation with P-450 3A4-catalyzed activities in various liver samples. Cigarette smoke condensate strongly inhibited the activation of several potent procarcinogens by human liver microsomes, particularly the reactions catalyzed by P-450 1A2, but was not so inhibitory of the activation reactions catalyzed by P-450 3A4 and of P-450 2D6-catalyzed bufuralol 1'-hydroxylation. Genotoxic components of the cigarette smoke condensate were extracted by using copper phthalocyanine cellulose (blue cotton). Genotoxicity of this extract was observed only after activation by P-450, and the inhibition of P-450 1A2 activities by these extracts was slight.(ABSTRACT TRUNCATED AT 400 WORDS)

Aflatoxin B1↗

PubMed1990

[Dynamic esophageal scintigraphy by a condensed imaging method].

The paper is concerned with preliminary evaluation of a method of condensed imaging during processing of the results of dynamic esophageal scintigraphy to detect motor evacuatory function of the esophagus. Altogether 34 patients (20 patients with primary esophageal cancer and 14 without G. I. tract pathology) were investigated. Comparison of the results of analysis of dynamic esophageal scintigraphy by a method of condensed imaging and standard methods of diagnostic data processing has shown that a condensed image of the esophagus objectively reflects some passage features of a food lump in the organ. Condensed imaging seems superior for analysis of the results of investigation and diagnostic data storage. However, this method must not be regarded as an alternative one ruling out a necessity of analysis of esophageal histograms and calculation of RP transport in the esophagus.

Adolescent↗

PubMed1989

Model for the formation of double minutes from prematurely condensed chromosomes of replicating micronuclei in drug-treated Chinese hamster ovary cells undergoing DNA amplification.

Double minutes (DM) have been associated with gene amplification in drug-resistant cells and tumor cells. However, the mechanisms by which DM are formed have not been elucidated. We present here a model to describe a possible mechanism of DM formation based on the observations made in two independent early drug-selected multidrug-resistant cell lines and from in vitro somatic cell fusion experiments between synchronized S- and M-phase cells. The multidrug-resistant cell lines contain both DM and amplified mdr (P-glycoprotein) gene. Cytogenetic analyses of cells at early stages of selection revealed the presence of a number of micronuclei in a subpopulation of these cells. These micronuclei were often asynchronous in their progression through the cell cycle. As a result, premature condensation of micronuclear chromatin was often observed in metaphase plates. The pulverized chromatin pattern seen in certain instances of S-phase prematurely condensed chromosomes displays a striking resemblance to DM structures. These DM-like structures are linked by replicating DNA as revealed by DNA labeling experiments. Somatic cell hybrids between S- and M-phase cells when grown in vitro demonstrated that S-phase prematurely condensed chromatin indeed gives rise to extra chromosomal structures in the successive cell generations. It is hypothesized that distinct DM-like structures may arise from the partially replicated and prematurely condensed S-phase chromosomes following their liberation as extra chromosomal entities after replication and/or recombination in the succeeding division cycle(s). The enrichment for DM containing specific genes in drug-resistant cells may result from the subsequent drug selections.

Animals↗

PubMed1988

[Evaluation of the apical seal produced by a hybrid root canal filling method, combining lateral condensation and thermomechanical compaction].

The present study measured apical leakage to a dye in roots filled by a hybrid root canal filling method, combining lateral condensation and thermomechanical compaction. The canals of 52 extracted human maxillary anterior teeth were endodontically prepared and divided into 3 groups. Lateral condensation was used in one group. The roots of the second one were filled using thermomechanical compaction. The roots of the third group were filled using hybrid method. After immersion in Procion Brilliant Green, the roots were cleared for measuring the depth of penetration of the dye under stereomicroscope. The roots filled with the hybrid method leaked less than the lateral condensation group, yet the difference was not significant (P greater than 0.05). The roots filled with both hybrid method and lateral condensation leaked significantly less (p less than 0.05) than the thermomechanical compaction group.

Dental Leakage↗

PubMed1984

Chromosome condensation and decondensation factors in the life cycle of eukaryotic cells.

In this chapter, we have attempted to review our recent work pertaining to the regulation of the chromosome condensation-decondensation cycle within the life cycle of mammalian cells. The results summarized here strongly suggest that this sequence of events may be regulated by different protein factors. Mitotic factors injected into fully grown X. laevis oocytes induce meiotic maturation, i.e., GVBD and chromosome condensation. These factors, which accumulate slowly in the beginning of G2 and reach a threshold at the G2-mitosis transition, have a great affinity for chromatin and are localized on metaphase chromosomes, as well as in the cytoplasm. They are nondialyzable, heat- and Ca2+-sensitive, Mg2+-dependent nonhistone proteins with an approximate molecular mass of 100,000 Da. At the telophase of mitosis, the mitotic factors are rapidly inactivated by another set of factors, IMF. IMF are also nondialyzable nonhistone proteins, but unlike mitotic factors, are heat-stable. They are also stable over a broad pH range, but are extremely sensitive to low pH. IMF are activated at telophase and remain active throughout the G1 period, thus coinciding with the process of chromosome decondensation. Although evidence implicating IMF in the regulation of chromosome decondensation is still largely circumstantial, data summarized here nevertheless suggest a strong correlation between these two phenomena. The way in which mitotic factors and IMF might bring about the condensation-decondensation of chromosomes has not been established. Our studies on the role of protein phosphorylation and the use of monoclonal antibodies specific for mitotic cells have provided some evidence implicating nonhistone protein phosphorylation-dephosphorylation in the regulation of mitosis. A causal link between these events is suggested, but remains to be established. Characterization of these factors will help us learn about their functions, as well as lead to a better understanding of the events regulating the chromosome condensation-decondensation cycle in eukaryotic cells.

Antibodies, Monoclonal↗

PubMed1984

Analysis of proteins associated with chromosome condensation in baby hamster kidney cells.

To identify proteins concerned with chromosome condensation processes, we used a temperature-sensitive mutant, tsBN2 derived from BHK21, in which premature chromosome condensation occurred at high temperature. When the proteins synthesized in tsBN2 during the induction of premature chromosome condensation were analyzed by two-dimensional gel electrophoresis, we found that an acidic protein with a molecular weight of 35,000 was specifically associated with chromosome condensation. In the normal cell cycle, this protein was synthesized from the G2 through the M phase. The protein was located mainly in the chromosome fraction and was phosphorylated.

Animals↗

PubMed1976

[C- and Q-chromatin of the experimentally condensed human interphase chromosomes].

Condensed interphase chromosomes of the cultured human lymphocytes obtained by the fusion of interphase and metaphase cells were studied using C- and Q-bands techniques. The appearance and localization of the constitutive heterochromatin blocks on condensed chromosomes at G1-period were the same as on the metaphase ones. These characters were used for a group and individual identification of some chromosomes condensed at G1-period and for a study of the association of the constitutive heterochromatin blocks in the interphase nuclei. The fluorescent analysis of the chromosomes condensed at G1-period detected some bright fluorescent blocks of the constitutive heterochromatin.

Cell Division↗

PubMed1977

Analysis of automobile exhaust condensates.

1. On the basis of figures for the production of PAH during the Europa drive cycle by 100 passenger cars and those for the consumption of petrol in the Federal Republic of Germany, an annual emission of 1,850 kg benzo[a]pyrene from petrol engine vehicles has been calculated. 2. The carcinogenic effect of benzo[a]pyrene accounts for only 9% of the total activity of exhaust condensates. 3. The amounts of other known carcinogenic PAH, such as benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[j]fluoranthene, indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene are shown in Table 2. (table: see text). Assuming that there is no significant promoting or hyper-additive effect, it can be estimated that these six known carcinogenic PAH contribute about 10-15% of the total carcinogenicity. 4. Six unknown PAH were found: cyclopenteno[cd]pyrene (mol wt 226), methylenebenzo[a]pyrene (mol 264), methylenebenzo[e]pyrene (mol wt 264), methylenebenzo[ghi]perylene (mol wt 288), PAH mol wt 300A and PAH mol wt 300B. It is reasonable to assume that these unknown PAH account for the predominant part of the carcinogenic effect. Biological tests with these pure substances are being undertaken by Drs Pott, Pfeiffer and Habs. 5. It has been shown that almost all of the carcinogenic effect of automobile exhaust condensates is due to PAH. To support this claim, the carcinogenic effects of the exhaust condensate should be compared with those of a mixture of the known and unknwon PAH in the same proportions as are found in the exhaust condensate. The gas chromatogram of such a mixture is shown in Figure 6.

Benzopyrenes↗

PubMed1977

Experimental results with percutaneous applications of automobile exhaust condensates in mice.

The induction of squamous-cell carcinoma and papillomas in mice after 80 weeks' skin painting with different doses of automobile exhaust condensates and their fractions is described. The results demonstrate that the carcinogenic activity of the condensate resides in its polycyclic aromatic hydrocarbon fractions. Benzo[a]pyrene accounts for approximately 9% of the activity of the condensate. The sebaceous gland suppression test, used as a screening method, is predictive of carcinogenicity and is positive for those condensate subfractions which contain carcinogenic PAH.

Animals↗