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J An

Publications and source records attributed to J An.

67 records · Page 4Linked to original sources
PubMed1994

[Endothelial cell injury and changes in anti-coagulation properties induced by burn serum in vitro].

The purpose of this study is to clarify the effect of burn rabbit serum on the function and structure of endothelial cells in vitro. Morphological study (inverted microscopy, scanning electron microscopy), and determinations of LDH, 6-keto-PGF1 alpha and tissue-type plasminogen activator in the culture medium, changes in the ability of anti-adhesion of platelet to endothelial cells and anti-aggregation property of platelet, etc. were performed. The main results and conclusions were as follows: (1) Rabbit serum obtained in the early stage exerted obvious toxic effects on endothelial cells, functional changes appeared earlier than structural, and in the later changes in intercellular junction and cellular surface appeared earlier; (2) Burn rabbit serum significantly reduced the ability of anti-adhesion of platelet to endothelial cell and anti-aggregation property of platelet, and it might be the primary cause of local micro-thrombosis; (3) Because of the destruction of endothelial surface, the ability of fibrinolysis of endothelial cells was reduced. The activity of tPA might be inhibited b PAI-1, although the content of tPA in the culture medium seemed to be increased after endothelial cell injury.

Animals↗
PubMed1994

Dynamic changes of fibrinopeptides A and B in sera of burn patients and their effects on vascular endothelial cells.

In this study, dynamic changes of fibrinopeptides A and B (FPA, FPB) in sera of burns patients are determined with an HPLC method. On this basis detrimental effects of FPA and FPB on vascular endothelial cells (VEC) are observed in vitro. The main results are as follows: (1) FPA and FPB in 18 burn patients' sera increase at day 2 postburn, reach peaks at days 5-7 postburn, then decline after day 15 postburn, and return to the control levels at day 25 postburn. The fluctuations in FPA and FPB levels in burn patients' sera are parallel to the progress of burn illness. The measurements of FPA and FPB levels in burn patients' sera may be useful in evaluating patients' condition. (2) FPA and FPB are detrimental to the cultured VEC in vitro. Characteristics of their injurious effects are: specific, irreversible and dose dependent. FPA and FPB may play an important role in endothelial injury.

Adolescent↗
PubMed1993

Polymerase chain reaction-based deletion screening of bleomycin induced 6-thioguanine-resistant mutants in Chinese hamster ovary cells: the effects of an inhibitor and a mimic of superoxide dismutase.

Bleomycin-induced 6-thioguanine-resistant mutants pretreated with or without TRIEN (triethylenetetramine), a superoxide dismutase (SOD) inhibitor, or TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), an SOD mimic, were analyzed by polymerase chain reaction (PCR)-based deletion screening in a Chinese hamster ovary (CHO) clone K1-BH4 and its derivative AS52 cells. As we proposed earlier, TRIEN would decrease and TEMPOL would increase the intracellular level of hydroxyl radical leading to a higher and lower recovery of deletion mutants. We found that the proportion of the deletion mutants induced by bleomycin at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in K1-BH4 cells was 45.5% (25/55). The proportion of deletion HPRT- mutants induced by bleomycin pretreated with TRIEN was 31.0% (9/29) and with TEMPOL was 50.0% (14/28). The proportion of deletion mutants induced by bleomycin on the xanthine-guanine phosphoribosyltransferase (gpt) gene in AS52 cells was 61.0% (36/59). The proportion of deletion GPT- mutants induced by bleomycin pretreated with TRIEN was 56.8% (21/37) and with TEMPOL was 61.4% (27/44). The trend of the change of the proportion of bleomycin-induced deletion mutants as affected by TRIEN and by TEMPOL provides molecular evidence for the involvement of reactive oxygen species (ROS) in bleomycin mutagenesis in mammalian cells, in which deletion is a major type of induced mutation.

Animals↗
PubMed1993

Mutagenicity and cytotoxicity of 2-methoxyethanol and its metabolites in Chinese hamster cells (the CHO/HPRT and AS52/GPT assays).

2-Methoxyethanol (ethylene glycol monomethyl ether) (EGME), is one of the most commonly used solvents for industrial and consumer products. Although the solvent has been shown to be a reproductive toxin the genotoxic activities of EGME especially its metabolites, have not been adequately investigated. The mutagenicity and cytotoxicity of EGME and its major metabolites, methoxyacetaldehyde (MALD) and methoxyacetic acid (MAA) in Chinese hamster ovary (CHO) cells were therefore examined by us. We have determined the mutagenicity of these compounds at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in CHO-K1-BH4 cells (CHO/HPRT assay) and the xanthine-guanine phosphoribosyl transferase (gpt) locus in CHO AS52 cells (AS52/GPT assay). The results show that these chemicals are not mutagenic to the hprt locus in CHO-K1-BH4 cells either with or without rat liver S9 mix as the metabolic activating system. With AS52 cells, only MALD is mutagenic in the absence of S9. It induced a dose-dependent mutagenic response. A dose-dependent cytotoxicity was induced by all compounds in both cell lines. MALD is the most and EGME is the least cytotoxic compounds. Our study shows that a metabolite of EGME, MALD, is highly cytotoxic and likely induces deletion-type mutations in AS52 cells. The genotoxic effect of EGME is, therefore, dependent upon its metabolism and its detection is dependent upon the assays used.

Animals↗
PubMed1993

Collection and transfusion of blood and blood components in the United States, 1989.

To probe recent trends in transfusion practice and their effect on the adequacy of the national blood resource, transfusions and collections in the United States in 1989 were studied, by using data shared by the American Association of Blood Banks, the American Red Cross, and the Council of Community Blood Centers, together with results from a sample survey of the 3600 hospitals that were not members of the national organizations. Statistical methods were used to estimate national activities. The total US supply of blood in 1989 was 14,229,000 units, an increase of 1.2 percent over the supply in 1987. Red cell transfusions were 12,059,000 units. A total of 3,159,000 patients underwent transfusion with whole blood and/or red cells (mean, 3.8 units/patient). Preoperative autologous deposits of 655,000 units by 310,000 patients represented an increase of 65 percent over the level in 1987. However, only 356,000 units (54%) were transfused to the patients who preoperatively deposited them; of the remainder, 13,000 units were crossed over for transfusion to other patients, while 286,000 units were never used. Directed donations, 350,000 units, were provided for 130,000 intended recipients, but only 97,000 units (28%) were transfused to their intended recipients; of the balance, 59,000 units (17%) were crossed over and 194,000 units (55%) were never transfused. Total platelet transfusions were equivalent to 7,258,000 units in 1989, for an increase of 13.7 percent over totals in 1987.

Blood Component Transfusion↗
PubMed1993

Retinoic acid induction of major histocompatibility complex class I genes in NTera-2 embryonal carcinoma cells involves induction of NF-kappa B (p50-p65) and retinoic acid receptor beta-retinoid X receptor beta heterodimers.

Retinoic acid (RA) treatment of human embryonal carcinoma (EC) NTera-2 (NT2) cells induces expression of major histocompatibility complex (MHC) class I and beta-2 microglobulin surface molecules. We found that this induction was accompanied by increased levels of MHC class I mRNA, which was attributable to the activation of the two conserved upstream enhancers, region I (NF-kappa B like) and region II. This activation coincided with the induction of nuclear factor binding activities specific for the two enhancers. Region I binding activity was not present in undifferentiated NT2 cells, but binding of an NF-kappa B heterodimer, p50-p65, was induced following RA treatment. The p50-p65 heterodimer was produced as a result of de novo induction of p50 and p65 mRNAs. Region II binding activity was present in undifferentiated cells at low levels but was greatly augmented by RA treatment because of activation of a nuclear hormone receptor heterodimer composed of the retinoid X receptor (RXR beta) and the RA receptor (RAR beta). The RXR beta-RAR beta heterodimer also bound RA responsive elements present in other genes which are likely to be involved in RA triggering of EC cell differentiation. Furthermore, transfection of p50 and p65 into undifferentiated NT2 cells synergistically activated region I-dependent MHC class I reporter activity. A similar increase in MHC class I reporter activity was demonstrated by cotransfection of RXR beta and RAR beta. These data show that following RA treatment, heterodimers of two transcription factor families are induced to bind to the MHC enhancers, which at least partly accounts for RA induction of MHC class I expression in NT2 EC cells.

Animals↗
PubMed1993

Quantitative and molecular analyses of genetic risk: a study with ionizing radiation.

Mammalian cells in culture have been used to study the genetic effects of physical and chemical agents. We have used Chinese hamster ovary (CHO) cells, clone K1-BH4, to quantify mutations at the X-linked, large (35 kb) hypoxanthine-guanine phosphoribosyltransferase (hprt) locus (the CHO/HPRT assay) induced by environmental agents. By transfecting an hprt-deletion mutant CHO cell line with the plasmid vector pSV2gpt, we isolated a transformant, AS52. AS52 cells carry a single functional copy of an autosomal, small (456 bp) xanthine-guanine phosphoribosyltransferase (gpt) gene (the bacterial equivalent of the mammalian hprt gene; AS52/GPT assay). We found that ionizing radiations such as X-rays and neutrons and oxidative genotoxic chemicals such as Adriamycin, bleomycin, hydrogen peroxide, and potassium superoxide are much more mutagenic to the gpt gene in AS52 cells than to the hprt locus in K1-BH4 cells. The hypermutability of the gpt gene probably results from a higher recovery of multilocus deletion mutants in AS52 cells than in K1-BH4 cells, rather than a higher yield of induced mutants. These results demonstrate that the use of the hprt locus alone could lead to an underestimate of the genetic risk of these agents. Analyses of the mutation spectrum using a polymerase chain reaction-based deletion screening and DNA sequencing procedure showed that a high proportion of HPRT- and GPT- mutants induced by X-rays carry deletion mutations. Thus, both the mutant frequency and mutation spectrum need to be considered in assessing the genetic risk of ionizing radiation and oxidative genotoxic chemicals.

Animals↗
PubMed1992

Effects of an inhibitor and a mimic of superoxide dismutase on bleomycin mutagenesis in Chinese hamster ovary cells.

We have investigated the roles of reactive oxygen species (ROS) in bleomycin (BLM)-induced gene mutations in Chinese hamster ovary (CHO) cells using a superoxide dismutase (SOD) inhibitor, triethylenetetramine (TRIEN), and a SOD mimic, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEM-POL), to lower and increase intracellular 'SOD activity', respectively. Pretreatment of CHO cells with TRIEN (1 mM) for 1 h enhanced the mutagenic response of BLM (5-50 micrograms/ml, 1 h treatment) in the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus in CHO cell clone K1-BH4 (CHO/HPRT assay) and the xanthine-guanine phosphoribosyltransferase (gpt) gene in a CHO-K1 cell derivative AS52 (AS52/GPT assay). Pretreatment with TEMPOL (1 mM) for 1 h decreased the BLM (20-100 micrograms/ml, 1 h treatment) mutagenicity in the AS52/GPT assay. The mutagenic response of BLM appears to be modulated by the intracellular level of 'SOD activity' and hence the intracellular level of ROS. These data provide further evidence for the involvement of ROS in bleomycin mutagenesis in mammalian cells.

Animals↗
PubMed1988

[Effect of Na2SeO3 on the damages of genetic materials induced by MNNG in children's foreskin fibroblasts in vitro].

In order to study the effect of selenium on anticarcinogenesis, micronuclei (MN) and chromosome aberrations (CA) were used as the indexes to reflect the damages on the genetic materials induced by MNNG in children's foreskin fibroblasts in vitro. In the MN test, the final concentrations of Na2SeO3 were 10(-7), 10(-6), 10(-5) and 10(-4) M and MNNG, 10(-5)M. In the CA test, Na2SeO3 were used in 10(-7), 10(-6) and 10(-5)M and MNNG, 10(-6)M as the final concentrations. Relative to the time of MNNG treatment, the cells were exposed to Na2SeO3 4 hours before and at the same time as with the carcinogen. The results showed that the MN% (number of cells out of one thousand MN) was reduced from 4.31 +/- 0.91% to 1.55 +/- 0.54% and 1.54 +/- 0.54% (P less than 0.05), respectively. The CA% (the percentage of the cell with CA) was reduced from 86 +/- 7% to 34 +/- 9% and 33 +/- 9% (P less than 0.05), respectively. However there was no like results when the cells were treated with Na2SeO3 and MNNG simultaneously. Na2SeO3 had no significant protective effects on the cells when the concentration was 10(-7)M. If the dose was 10(-4)M or more, Na2SeO3 became toxic to the cells. The results suggested that the protection of Na2SeO3 on the damages of genetic materials induced by MNNG be time and dose dependent.

Cells, Cultured↗
PubMedDate not supplied

Thermodynamic databases for proteins and protein-nucleic acid interactions.

Thermodynamic data regarding proteins and their interactions are important for understanding the mechanisms of protein folding, protein stability, and molecular recognition. Although there are several structural databases available for proteins and their complexes with other molecules, databases for experimental thermodynamic data on protein stability and interactions are rather scarce. Thus, we have developed two electronically accessible thermodynamic databases. ProTherm, Thermodynamic Database for Proteins and Mutants, contains numerical data of several thermodynamic parameters of protein stability, experimental methods and conditions, along with structural, functional, and literature information. ProNIT, Thermodynamic Database for Protein-Nucleic Acid Interactions, contains thermodynamic data for protein-nucleic acid binding, experimental conditions, structural information of proteins, nucleic acids and the complex, and literature information. These data have been incorporated into 3DinSight, an integrated database for structure, function, and properties of biomolecules. A WWW interface allows users to search for data based on various conditions, with different display and sorting options, and to visualize molecular structures and their interactions. These thermodynamic databases, together with structural databases, help researchers gain insight into the relationship among structure, function, and thermodynamics of proteins and their interactions, and will become useful resources for studying proteins in the postgenomic era.

DNA↗
PubMedDate not supplied

[Analysis of structural motifs of proteins using sets of codes, describing local structures].

An amino acid sequence pattern conserved among a family of proteins is called motif. It is usually related to the specific function of the family. On the other hand, functions of proteins are achieved by their 3D structures. Specific local structures, called structural motifs, are considered related to their functions. However, searching for common structural motifs in different proteins is much more difficult than for common sequence motifs. We are attempting in this study to convert the information about the structural motifs into a set of one-dimensional digital strings, i.e., a set of codes, to compare them more easily by computer and to investigate their relationship to functions more quantitatively. By applying the Delaunay tessellation to a 3D structure of a protein, we can assign each local structure to a unique code that is defined so as to reflect its structural feature. Since a structural motif is defined as a set of the local structures in this paper, the structural motif is represented by a set of the codes. In order to examine the ability of the set of the codes to distinguish differences among the sets of local structures with a given PROSITE pattern that contain both true and false positives, we clustered them by introducing a similarity measure among the set of the codes. The obtained clustering shows a good agreement with other results by direct structural comparison methods such as a superposition method. The structural motifs in homologous proteins are also properly clustered according to their sources. These results suggest that the structural motifs can be well characterized by these sets of the codes, and that the method can be utilized in comparing structural motifs and relating them with function.

Amino Acid Motifs↗
PubMedDate not supplied

Use of a rat cDNA probe specific for the Y chromosome to detect male-derived cells.

A cDNA probe that exhibits specificity for the rat Y chromosome was generated by using a set of primers specific to the murine Sry gene, the sex-determining region of the Y chromosome. A 459-base pair (bp) DNA fragment was obtained by polymerase chain reaction (PCR) amplification from male, but not female, rat genomic DNA (EMBL Nucleotide Sequence Database accession number X89730). This DNA fragment was purified, cloned using a vector, and digested with EcoR1 to yield a 270-bp DNA fragment. This 270-bp cDNA fragment, when used as a probe in Southern blot analysis of rat DNA, was observed to bind to three separate bands of approximately 2.3, 5.0, and 7.0 kb in size. The binding was demonstrated with male, but not female, genomic DNA. Another set of primers was generated to sequences within the 270-bp fragment that produced a PCR product of 104 bp. This DNA fragment, when used as a probe in Southern blot analysis, enabled PCR detection of at least 0.1% male cells in a mixed population of female cells. These cDNA probes should prove useful in studies designed to track cell populations (e.g., tumor metastasis and hemopoietic cells after bone marrow transplantation) in syngeneic male/female pairs. In addition, a cDNA probe that is specific for the rat Sry gene might be valuable in studies of fetal male sexual development or the study of spermiogenesis.

Animals↗