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Biomedical subjects

J An

Publications and source records attributed to J An.

At least 55 records · Page 3Linked to original sources
PubMed1997

[The correlation between expression of oncogene protein products p53, p21, p185 and cell differentiation and prognosis in rhabdomyosarcoma].

OBJECTIVE: To study the correlation between expression of oncogene protein products p53, P21, p185 and histological type, cell differentiation and prognosis in rhabdomyosarcoma (RMS). METHODS: 41 RMS cases which had follow-up material were selected for this study. Expression of protein products of oncogene p53, p21 and p185 were synchronously detected and compared by immunohistochemical ABC method. RESULTS: The positive rates for p53, p21 ras and P185 c-erbB-2 were 72%, 68% and 60% respectively. Positive expression did not relate to age, sex or RMS histological type, but related to the degree of RMS differentiation. The positive rate of p53 ad p21 ras in well differentiated cases were 42.9% and 28.6% while that of the poorly differentiated group was 85% and 80% respectively (P < 0.05). The psoitive rate of p53 in the RMS group with metastasis was 86.6%, significantly higher than that of the non-metastasized group, which was 66.7% (P < 0.05). There was a significant difference between those with one year survival, whose p52 positive rate was 86.7% and those who survived for more than 3 years, whose p53 positive rate was 47.1% (P < 0.05). CONCLUSION: The results suggest that the irregular expressions of p53 and p21 were related to tumor differentiation and the degree of malignancy. p53 positivity may indicate a poor prognosis.

Adolescent↗
PubMed1997

A comparative study on morphology and immunohistochemistry of rhabdomyosarcoma and embryonal skeletal muscles.

OBJECTIVE: To investigate the histologic and histogenetic relationship between various types of rhabdomyosarcomas (RMS) and embryonal skeletal muscle (ESM) for further understanding of the histogenesis, classification and pattern of differentiation of RMS. METHODS: Fifty cases of variant types of RMS and 20 cases of ESM at different gestational ages were available. All specimens were stained with HE, PAS, Van Gieson, Masson, phosphotungstic acid hematoxilin and with antibodies for the demonstration of vimentin, desmin, HHF-35 and myoglobin by ABC method. RESULTS: The results showed that the order of positive expression and the intensity of positive reaction of the different immunohistochemical staining were consistent with the degree of differentiation of the tumor and the development of the ESM. It is obvious that each type of RMS is composed of tumor cells in different degree of differentiation and is derived from primitive mesodermal cells which are capable of potential differentiation towards mature skeletal muscles. CONCLUSIONS: Based on the results of this study, an ideal histologic classification of RMS should reflect not only the cell morphology and histologic structures but also the degree of differentiation of the tumor cells.

Adolescent↗
PubMed1996

Recombinant human bone morphogenetic protein-2 induces a hematopoietic microenvironment in the rat that supports the growth of stem cells.

In the mammalian bone marrow, stromal components support the growth and differentiation of blood cells. To study this complex system, we used a rat model in which ectopic hematopoietic tissue was induced to form after subcutaneous implantation of recombinant human bone morphogenetic protein (rhBMP-2). We showed that this organoid contained clonogenic precursors of both erythroid and myeloid lineages and progenitors competent to regenerate splenic lymphopoiesis. Furthermore, stem cells derived from ectopic foci conferred both short-term (30 day) and long-term (>6-month) protection in vivo against radiation-induced marrow aplasia. Lead shielding of the ectopic marrow in situ also permitted endogenous recovery of hematopoiesis after sublethal irradiation. Extending previous observations that most fibroblastoid cells of the marrow stain with the anti-ST3 antibody (but minimally with anti-ST4), whereas those growing from nonhematopoietic tissues react with anti-ST4, we found that analogous cells of the ectopic foci stained predominantly with anti-ST3. The ability to induce formation of a hematopoietic microenvironment from mesenchymal precursors may make possible the development of new strategies for the treatment of primary disorders of stem cells and irreversible stromal injury.

Animals↗
PubMed1995

Metabolism of xyloglucan generates xylose-deficient oligosaccharide subunits of this polysaccharide in etiolated peas.

Oligosaccharide subunits of xyloglucan were isolated from the stems and roots of etiolated pea plants and structurally characterized. The two most abundant subunits of pea xyloglucan are the well-known nonasaccharide, XXFG, and heptasaccharide, XXXG. In addition, significant amounts of oligosaccharides that have not previously been reported to be subunits of pea xyloglucan were detected, including a decasaccharide, XLFG, two octasaccharides, XLXG and XXLG, a pentasaccharide, XXG, and a trisaccharide, XG. Several novel oligosaccharide subunits, including the octasaccharide, GXFG, and the hexasaccharide, GXXG, were also found. Xyloglucan oligosaccharides generated by treatment of intact pea stem cell walls were compared to oligosaccharides generated by endoglucanase treatment of xyloglucan polysaccharides obtained by subsequent alkali extraction of the same cell walls. The results suggest that the xyloglucan in etiolated pea stems is distributed between at least two domains, one of which is distinguished by its enzyme accessibility. We further hypothesize that the chemical modification of a xyloglucan during cell-wall maturation depends on its physical environment (i.e., the domain in which it resides). For example, only the endoglucanase-released material, representing the enzyme-accessible xyloglucan domain, contains significant amounts of the two unusual oligosaccharide subunits, GXXG and GXFG, both of which have a nonreducing terminal glucosyl residue. This structure may be generated during cell-wall maturation by the sequential action of an endolytic enzyme (such as xyloglucan endotransglycosylase or endoglucanase) and an alpha-xylosidase.

Carbohydrate Sequence↗
PubMed1995

Cloning and characterization of 5E6(Ly-49C), a receptor molecule expressed on a subset of murine natural killer cells.

5E6 is a cell surface molecule expressed on a subpopulation of murine natural killer (NK) cells that are involved in the specific rejection of H-2d or H-2f (hemopoietic histocompatibility determinant 2) bone marrow cell grafts. Here, we isolated and cloned the gene encoding 5E6 and determined the nucleotide sequence of the cDNA. 5E6 is nearly identical to Ly-49C; the deduced amino acid sequence reveals a polypeptide of 266 amino acids with a molecular weight of 31,284 that contains multiple cysteine residues to explain its disulfide-linked homodimer structure and five potential N-linked glycosylation sites. 5E6 is a type II integral membrane protein with an extracellular carbohydrate recognition domain characteristic of C-type (Ca(2+)-dependent) animal lectins. Chromosomal mapping indicates that 5E6 is located within the NK gene complex on chromosome 6. The sequence of 5E6 mRNA and the degree of glycosylation of 5E6 protein are under genetic control. Immunoprecipitation before removal of N-linked sugars reveals different size molecules. There are several nucleotide differences among BALB/c, B6, and NZB mRNAs; however, none of them would be expected to affect N-glycosylation. Of particular interest are two findings: (a) BALB/c, B6, and (BALB/c x B6)F1 5E6 reduced molecules are approximately 65, 54, and 54 kD, and (b) the cDNA sequence of (BALB/c x B6)F1 is identical to B6. Thus, there appears to be allelic exclusion of 5E6 expression that may be related to the ability of F1 hybrid mice to reject parental H-2d bone marrow cell grafts.

Amino Acid Sequence↗
PubMed1995

The structure of a novel polysaccharide produced by Bradyrhizobium species within soybean nodules.

Certain strains of Bradyrhizobium japonicum and B. elkanii produce a polysaccharide within the root nodules of their legume host, soybean. These nodule polysaccharides (NPSs) were isolated and characterized. The NPS produced by B. elkanii strains proved to be identical in glycosyl composition and linkages to the extracellular polysaccharide (EPS) of this species indicating that the NPS and EPS for B. elkanii have identical structures (W.F. Dudman, Carbohydr. Res., 66 (1978) 9-23), [formula: see text] However, the structure of the NPS from B. japonicum proved to be quite different from that of its EPS. Methylation analysis of this NPS showed that it consists of 3-linked Gal, 3-linked Rha, 2,4-linked Rha, 4-linked Rha, and terminal 2-O-methyl GlcA in a 1:1:1:1:1 ratio. Stereochemical configurations of the glycosyl residues were determined by the preparation and analysis of trimethylsilyl (Me3Si) (-)-2-butyl glycosides. NMR spectroscopy (both 1H and 13C) showed that the Gal residue is alpha-linked, while all the other glycosyl residues are beta-linked. Oligosaccharides produced by periodate oxidation-Smith degradation were purified, as were oligosaccharides produced by partial acid hydrolysis. Characterization of the Smith degradation products by methylation analysis. NMR spectroscopy, electrospray-mass spectrometry, and characterization of the partial acid hydrolysate oligosaccharides showed that the repeating oligosaccharide unit of the NPS has the structure, [formula: see text]

Carbohydrate Sequence↗
PubMed1995

Cyclic (1R,3R)-1,3-dimethyltrimethylene [(5R)-2-hydroxy-5-methyl-5-(2- methyl-1,3-dioxolan-2-yl)-1-cyclohexen-1-yl]-phosphonate, a stable enol.

The title compound, C16H27O6P, was obtained from the rearrangement of the corresponding vinyl phosphate. 31P NMR experiments in solution have shown that this compound equilibrates to a mixture of three isomers in nearly equal proportions. In the crystalline state a single isomer is found which diffraction analysis identified as the enol form of the beta-keto phosphonate having R stereochemistry at atom C(8).

Crystallization↗
PubMed1995

Collection and transfusion of blood and blood components in the United States, 1992.

BACKGROUND: Studies were conducted to measure the state of the United States' national blood resource in 1992 and changes therein from 1989. STUDY DESIGN AND METHODS: With data supplied by the American Red Cross and the American Association of Blood Banks, as well as data from a stratified random-sample survey of 3350 non-American Association of Blood Banks hospitals, statistical methods were applied to estimate national blood activities in 1992. RESULTS: The total US blood supply in 1992 was 13,794,000 units, a decrease of 3.1 percent from 1989. Some 11,307,000 red cell units were transfused to 3,772,000 patients, an average of 3.0 units per transfused patient. Preoperative autologous blood deposits totaled 1,117,000 units, a 70-percent increase over 1989. Of this number, 566,000 units (50.7%) were transfused, 5,000 (4.4%) transferred to the allogeneic supply, and 546,000 (48.9%) discarded. Of 436,000 directed-donation units, 136,000 (31.2%) were transfused, 57,000 (13.1%) transferred to allogeneic supply, and 243,000 (55.7%) discarded. The total allogeneic blood supply, including imports, decreased by 7.4 percent from 1989, and allogeneic blood transfusions, including those to children, decreased by 8.6 percent. Over 8,300,000 platelet units were transfused; of these, some 3,600,000 were apheresis platelets. In addition, 2,255,000 units of plasma and 939,000 units of cryoprecipitate were transfused. CONCLUSION: While the US blood supply was adequate for transfusion needs in 1992, blood collections and red cell transfusions had decreased substantially since 1989.

Blood Banks↗
PubMed1995

Nitric oxide-mediated neurogenic relaxation in monkey mesenteric veins.

The purpose of this investigation was to determine if neurally induced vasodilatation is mediated by nitric oxide (NO) in monkey mesenteric veins. Helical strips of the monkey mesenteric vein were exposed to the bathing media for isometric tension recording, and perivascular nerves were stimulated by nicotine. Nicotine produced a contraction, which was potentiated by treatment with NG-nitro-L-arginine, a NO synthase inhibitor, the effect being reversed by L-arginine. The nicotine-induced contraction was reversed to a relaxation by prazosin. The relaxation was abolished by the NO synthase inhibitor, and it was restored by L-arginine. D-Enantiomers were without effect. The response was not influenced by timolol and indomethacin, but was abolished by hexamethonium and oxyhemoglobin. There were perivascular nerve fibers containing NO synthase immunoreactivity in the monkey vein. Neurally induced venous relaxations appear to be mediated by NO from perivascular nerves, as seen in dog and monkey mesenteric arteries. It is concluded that monkey mesenteric veins are innervated by nitroxidergic and adrenergic nerves, which may balance the vascular tone.

Animals↗
PubMed1995

[Monocyte recruitment in blood vessel wall].

Adhesion of monocytes to vascular endothelial cell (EC) and subsequent stretching and migration over the luminal surface of EC can be seen in some pathophysiological process in the body. This is called "monocyte recruitment". Adhesive molecules and adhesive receptors take part and play an important role in the process. The recruitment can be regulated by many cytokines and chemoattractants. In this article the process, character, mechanism, regulation and effect of monocyte recruitment will be discussed.

Cell Adhesion↗
PubMed1995

[Studies on mode of human infection with Echinochasmus liliputanus].

Epidemiological survey and experimental studies on the mode of human infection with Echinochasmus liliputanus were carried out in Chenqiaozhou Village, Hexian County, Anhui Province in 1992. The results showed that humans could be infected through drinking unboiled water containing E.liliputanus cercaria or eating raw fish containing the metacercaria. The infection rates of E. liliputanus were 1.5% in the inhabitants who did not drink raw water, and 20.1% in those who used to drink raw water. It was only the cercaria, not the metacercaria that was detected in the water from ponds of this village. None of the investigated inhabitants ate uncooked fish. The results indicated that drinking raw water containing E.liliputanus cercaria was a major way through which a humans were infected and eating food containing the metacercaria was a minor mode of human infection.

Animals↗
PubMed1994

Isolation and structural characterization of endo-rhamnogalacturonase-generated fragments of the backbone of rhamnogalacturonan I.

A combination of commercially available preparations of Aspergillus niger beta-D-galactosidase, endo-alpha-L-arabinanase, alpha-L-arabinosidase, and endo-beta-D-galactanase has been used to generate oligoglycosyl fragments of the backbone of rhamnogalacturonan I (RG-I) that had been isolated from the walls of suspension-cultured sycamore cells. The backbone-cleaving enzyme, which is present in the beta-D-galactosidase preparation, only fragments the RG-I backbone when many of the neutral oligoglycosyl side chains have been removed by the other exo- and endo- glycanases. The oligosaccharides released from the backbone were separated from the partially fragmented RG-I and then purified, as their oligoglycosyl aldonic acids, by HPAEC-PAD. Those backbone fragments with degrees of polymerization (dp's) between 2 and 11 were characterized using one- and two-dimensional 1H NMR spectroscopy, electrospray mass spectrometry, and glycosyl-residue and glycosyl-linkage composition analyses. Two series of oligoglycosyl fragments were identified. The quantitatively predominant series has the structure alpha-D-GalpA-(1 --> 2)- alpha-L-Rhap-[ --> 4)-alpha-D-GalpA-(1 --> 2)-alpha-L-Rhap-(1 --> ]n-4-D-GalpA, and the quantitatively minor series has the structure alpha-L-Rhap-[ --> 4)-alpha-D-GalpA-(1 --> 2)-alpha-L-Rhap-(1 --> ]n-4-D- GalpA (n = 1-5). Thus, the enzyme preparations contain an alpha-L-rhamnosidase in addition to the endo- rhamnogalacturonase. The products of the endo-rhamnogalacturonase provide additional evidence that the backbone of RG-I is composed of the diglycosyl repeating unit: --> 4)-alpha-D-GalpA-(1 --> 2)-alpha-L-Rhap- (1 -->. The endo-rhamnogalacturonase from the A. niger beta-D-galactosidase preparation and the endo- rhamnogalacturonase secreted by Aspergillus aculeatus [H.A. Schols et al. Carbohydr. Res., 206 (1990) 117-129] have the same substrate specificities and generate similar oligoglycosyl fragments.

Aspergillus niger↗
PubMed1994

Isolation and structural characterization of beta-D-glucosyluronic acid and 4-O-methyl beta-D-glucosyluronic acid-containing oligosaccharides from the cell-wall pectic polysaccharide, rhamnogalacturonan I.

Rhamnogalacturonan I (RG-I), a pectic polysaccharide isolated from the walls of suspension-cultured sycamore cells, was shown by glycosyl-residue composition analysis to contain D-glucosyluronic acid (GlcpA) residues (1 mol%) and 4-O-methyl-D-glucosyluronic acid (4-O-Me-GlcpA) residues (0.5 mol%). These monosaccharides were shown, by glycosyl-linkage analysis, to be present in RG-I as terminal nonreducing residues. The glycosyl sequences containing GlcpA and 4-O-Me-GlcpA were determined by structurally characterizing the acidic oligosaccharides released by partial acid hydrolysis of RG-I. Six acidic oligosaccharides were purified by semipreparative high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and characterized by glycosyl-residue and glycosyl-linkage composition analyses, GLC-CIMS, GLC-EIMS, electrospray MS (ESMS), and 1H NMR spectroscopy. We propose that three of the acidic oligosaccharides characterized, 4-O-Me-beta-D-GlcpA-(1-->6)-D-Gal, beta-D-GlcpA-(1-->6)-D-Gal, and beta-D-GlcpA-(1-->4)-D-Gal, originate from the galactosyl-containing side chains of RG-I. The three other acidic oligosaccharides characterized, alpha-D-GalpA-(1-->2)-L-Rha, alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GalpA+ ++-(1-->2)-alpha-L-Rha, and alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GalpA+ ++-(1-->2)-alpha-L- Rhap-(1-->4)-alpha-D-GalpA-(1-->2)-alpha-L-Rha, were generated by partial hydrolysis of the RG-I backbone. No evidence was obtained for the presence of galactosyluronic acid in the side chains of RG-I.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Sequence↗
PubMed1994

Polymerase chain reaction-directed DNA sequencing of bleomycin-induced "nondeletion"-type, 6-thioguanine-resistant mutants in Chinese hamster ovary cell derivative AS52: effects of an inhibitor and a mimic of superoxide dismutase.

Bleomycin-induced, 6-thioguanine-resistant, "non deletion" mutants pretreated with or without either TRIEN (triethylenetetramine), a superoxide dismutase (SOD) inhibitor, or TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a SOD mimic, were analyzed by polymerase chain reaction (PCR)-directed DNA sequencing in a Chinese hamster ovary (CHO) cell derivative, AS52. Among the 23 bleomycin-induced mutants, six have 3-bp 5'-TGA-3' deletions in the region of 366-371, five have single-base deletions, seven have base substitutions, three have insertions, and two have possible translocations. Among the 16 bleomycin-induced mutants pretreated with TRIEN, six have the 5'-TGA-3' deletion (366-371), two have single-base deletions, one has a 13-bp deletion, four have single-base substitutions, one has a double-base substitution, and two have insertions. Among the 17 bleomycin-induced mutants pretreated with TEMPOL, six have the same TGA deletions, two have single-base deletions, two have single-base insertions, four have single-base substitutions, one mutant has a 12-bp deletion, one has a 13-bp deletion, and one mutant shows no detectable change in its coding region in the DNA sequence. A possible shift from a ROS-mediated mutational spectrum to a spontaneous mutational spectrum by TRIEN further indicates that reactive oxygen species play an important role in bleomycin mutagenesis in mammalian cells.

Animals↗
PubMed1994

Use of a colorimetric protein phosphatase inhibition assay and enzyme linked immunosorbent assay for the study of microcystins and nodularins.

Microcystins and nodularins are cyclic peptide hepatotoxins and tumor promoters produced by several genera of cyanobacteria. Using a rabbit anti-microcystin-LR polyclonal antibody preparation, the cross-reactivity with 18 microcystin and nodularin variants was tested. A hydrophobic amino acid, 3-amino-9-methoxy-10-phenyl-2,6,8-trimethyl-deca-4(E),6(E)-dienoic acid (Adda), which has the (E) form at the C-6 double bond in both microcystin and nodularin, was found essential for these toxins to express antibody specificity. Modification of -COOH in glutamic acid of microcystin and nodularin did not alter their antigenicity. Antibody cross-reactivity of these toxins was compared with their ability to inhibit protein phosphatase type 1 (PP1). Detection of PP1 inhibition was done by measuring the inhibition effect of the toxins on p-nitrophenol phosphate activity toward PP1. PP1 was obtained as recombinant PP1 expressed in E. coli. The inhibition effect of five microcystins and two nodularins on recombinant PP1 activity toward p-nitrophenol phospate was measured in a microwell plate reader. The concentration of microcystin-LR causing 50% inhibition of recombinant PP1 activity (IC50) was about 0.3 nM, while that of two modified microcystins had a significantly higher IC50. Microcystin-LR and nodularin with the (z) form of Adda at the C-6 double bond or having the monoester of glutamic acid did not inhibit PP1. These three toxins were also nontoxic in the mouse bioassay. These results show the importance of Adda and glutamic acid in toxicity of these cyclic peptides and that PP1 inhibition is related to the toxins' mechanism of action.

Amino Acids↗
PubMed1994

Multiplex polymerase chain reaction-based deletion analysis of spontaneous, gamma ray- and alpha-induced hprt mutants of CHO-K1 cells.

Independent Chinese hamster ovary (CHO)-K1 cell mutants at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus were isolated from untreated, 60Co gamma ray- and 212Bi alpha-exposed cells and the genetic changes underlying the mutation determined by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. In the 71 spontaneous mutants analyzed, 77.5% of the clones showed no change in exon number or size, 15.5% showed a loss of a single exon, 4.2% showed a loss of 2-8 exons, and 2.8% showed loss of all nine hprt exons (total gene deletion). Exposure to 6 Gy of gamma rays, which reduced survival levels to 10%, produced a significantly different deletion spectrum that was shifted toward deletions with 45% of the 20 mutants analyzed showing a loss of a single exon and 30% showing a loss of all nine exons. Exposure to 2 Gy alpha radiation from 212Bi, a 220Rn daughter, a dose which also reduced survival levels to about 10%, resulted in a deletion spectrum similar to the gamma-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The alpha spectrum, however, was significantly different from both the spontaneous and gamma spectra with 55.1% of the alpha mutants showing a loss of all nine exons, 10.2% showing loss of a single exon, and 14.3% showing loss of 2-8 exons. Thus, alpha-radiation appears to produce larger intragenic deletions than gamma radiation. The results suggest that intragenic deletion size should be considered when low- and high linear energy transfer (LET) mutation spectra are compared.

Alpha Particles↗