Existence of the spin-glass state in amorphous Fe.
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Journal Article↗
Biomedical subjects
M Yu
Publications and source records attributed to M Yu.
[Study on construction of secluded treatment rooms].
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Cross Infection↗
A negative regulatory element upstream from the mouse Adh-1 gene can down-regulate a heterologous promoter.
Regulation of Adh-1 (encoding mouse alcohol dehydrogenase-A2) gene expression results from the interplay of positive and negative effects. We report here the detection and localization of a negative regulatory element (NRE) to the sequence between -754 and -732 bp relative to the transcription start point (tsp). This element, which we call Adh-1 NRE2, can down-regulate transcription from a strong heterologous promoter (the SV40 promoter+enhancer). Adh-1 NRE2 can function in both orientations and either upstream or downstream from the promoter, and thus has attributes characteristic of a 'silencer'. A protein that binds to the Adh-1 NRE is widespread in mouse tissues.
Alcohol Dehydrogenase↗
Finite-temperature theory of amorphous magnetic alloys.
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Journal Article↗
1-Deamino-8-D-arginine vasopressin (DDAVP) increases platelet membrane expression of glycoprotein Ib in patients with disorders of platelet function and after cardiopulmonary bypass.
1-deamino-8-D-Arginine vasopressin (DDAVP) shortens the bleeding time in some patients with platelet dysfunction and decreases blood loss in some cardiopulmonary bypass patients. We studied platelet membrane glycoproteins in patients with von Willebrand disease (vWD), disorders of platelet function, and in cardiopulmonary bypass patients after infusion of 0.3 microgram/kg of DDAVP. Platelets from 8 cardiopulmonary bypass patients, receiving DDAVP immediately after surgery, were compared to those of 14 patients not receiving DDAVP. We also studied 12 patients with vWD, and 8 patients with platelet dysfunction receiving DDAVP. Fixed platelets, stained with monoclonal fluorescein (FITC)-labeled antibodies directed against GPIb (CD42b antigen), GPIb/IX, GPIIb/IIIa (CD41a antigen), CD63 antigen (a platelet activation protein), and P-selectin (CD62 antigen) were studied by flow cytometry. Binding of CD42b monoclonal antibody (MoAb) and anti-GPIb/IX to platelets from both groups of bypass patients increased during the 18-20 hr after surgery, but the group receiving DDAVP showed the greater increase (P = 0.032). Platelets from patients receiving DDAVP for vWD or for platelet dysfunction, had increases in CD42b MoAb and anti-GPIb/IX binding (P < 0.01) that coincided with shortening of their bleeding time. No changes were seen in binding of other antibodies. When platelets from normal donors were incubated with DDAVP for 20 hr, there were increases in platelet surface CD42b MoAb binding, while immunogold-stained transmission electron micrographs of permeabilized platelets demonstrated decreases in cytoplasmic CD42b MoAb binding. DDAVP increases platelet membrane GPIb expression in a variety of patients and may account for improvement in hemostasis seen in some studies. Redistribution of GPIb from the cytoplasm to the membrane may account for this increased expression.
Adult↗
A simple model for estimating protein solubility in aqueous polymer solutions.
A simple scaling analysis of protein solubility in semi-diluted polymer aqueous solutions was derived based on the recent theoretical development of Abbott et al. on the interactions between protein spheres and entangled polymer coils and the experimental observations of Atha and Ingham on the polymer-induced protein precipitation. Both the hard-sphere nature of the protein and the flexibility of the polymer coils have been taken into account in the model. The experimental data can be fitted by using this model with physically reasonable values of the exponent. This approach may be useful in estimating protein solubilities in water in the presence of polymer from limited and usually costly experimental data.
Chemical Phenomena↗
Collagen induced MMP-2 activation in human breast cancer.
Matrix metalloproteinase-2 (MMP-2), a zymogen requiring proteolytic activation for catalytic activity, has been implicated broadly in the invasion and metastasis of many cancer model systems, including human breast cancer (HBC). MMP-2 has been immunolocalized to carcinomatous human breast, where the degree of activation of MMP-2 correlates well with tumor grade and patient prognosis. Using Matrigel assays, we have stratified HBC cell lines for invasiveness in vitro, and compared this to their potential for metastatic spread in nude mice. HBC cell lines expressing the mesenchymal marker protein vimentin were found to be highly invasive in vitro, and tended to form metastases in nude mice. We have further discovered that culture on collagen-I gels (Vitrogen; Vg) induces MMP-2-activator in highly invasive but not poorly invasive HBC cell lines. As seen for other MMP-2-activator inducing regimens, this induction requires protein synthesis and an intact MMP-2 hemopexin-like domain, appears to be mediated by a cell surface activity, and can be inhibited by metalloproteinase inhibitors. The induction is highly specific to collagen I, and is not seen with thin coatings of collagen I, collagen IV, laminin, or fibronectin, or with 3-dimensional gels of laminin, Matrigel, or gelatin. This review focuses on collagen I and MMP-2, their localization and source in HBC, and their relationship(s) to MMP-2 activation and HBC metastasis. The relevance of collagen I in activation of MMP-2 in vivo is discussed in terms of stromal cell: tumor cell interaction for collagen I deposition, MMP-2 production, and MMP-2-activation. Such cooperativity may exist in vivo for MMP-2 participation in HBC dissemination. A more complete understanding of the regulation of MMP-2-activator by type I collagen may provide new avenues for improved diagnosis and prognosis of human breast cancer.
Amino Acid Sequence↗
Serine protease inhibitors block N-terminal arginylation of proteins by inhibiting the arginylation of tRNA in rat brains.
The tRNA mediated, posttranslational, N-terminal arginylation of proteins occurs in all eukaryotic cells. In nervous tissue, these reactions can be inhibited by endogenous molecules with a molecular weight of between one thousand and five thousand. In the present experiments, exogenous serine protease inhibitors (10(-5) M or less) but not other types of protease inhibitors, were found to be able to block the arginylation of protein in extracts of rat brain homogenates. Inhibition was not by the usual mode of action of protease inhibitors, but by interfering (non-competitively) with the charging of tRNA. Since arginylated proteins are rapidly ubiquitinated and degraded by cytosolic proteases, serine protease inhibitors may act to stabilize proteins by a dual mechanism of inhibiting arginylation as well as inhibiting serine proteases.
Animals↗
Augmented interferon-gamma, interleukin-4 and transforming growth factor-beta mRNA expression in blood mononuclear cells in myasthenia gravis.
The abnormal T lymphocyte-dependent production of antibodies to the nicotinic acetylcholine receptor (AChR) in myasthenia gravis (MG) suggests a role for immunoregulatory cytokines. We examined the T helper type 1 (Th1) cell-associated interferon-gamma (IFN-gamma) that promotes cell-mediated immunity, the Th2 cell-related interleukin-4 (IL-4) that augments B cell immunity, and transforming growth factor-beta (TGF-beta) that downregulates immune responses but enhances isotype switching. Blood mononuclear cells (MNC) expressing cytokine mRNA were enumerated after in situ hybridization with labelled complementary DNA oligonucleotide probes for IFN-gamma, IL-4 and TGF-beta. MG patients had elevated numbers of cells expressing IFN-gamma and IL-4 compared to patients with non-inflammatory neurological diseases and healthy controls, implying that both Th1- and Th2-like cells are involved in MG. TGF-beta-positive cells were also elevated in MG. The levels of cytokine-positive MNC were similar in MG and in control patients with other inflammatory neurological diseases. There were no associations between numbers of cytokine-positive blood MNC and clinical variables of MG, but individual patients need to be studied over the course of MG to clarify a relation between the cytokines under study and clinical or laboratory variables of MG.
Adolescent↗
Expression of the outer capsid proteins VP2 and VP5 of bluetongue virus in Saccharomyces cerevisiae.
cDNAs transcribed from bluetongue virus serotype 1 (Australia) ds RNA 2 and ds RNA 6 coding for the major neutralising antigen VP2 and the outer capsid protein VP5, respectively, were amplified in polymerase chain reactions and ligated downstream of the copper-inducible metallothionein promoter in the yeast expression plasmid pYELC5. Saccharomyces cerevisiae transformed with the recombinant plasmid pYELC5-VP2 expressed full-length VP2 only following induction with 1 mM CuSO4 and reached the maximum level after 6 h. In contrast, S. cerevisiae transformants harboring the recombinant plasmid pYELC5-VP5 expressed VP5 constitutively, although induction increased the level to a maximum after 4 h. A sheep trial was done testing the recombinant proteins, however it was shown that none of these were effective immunogens for eliciting a protective response against a subsequent challenge with bluetongue virus. An analysis of the yeast expression products for the VP2 outer coat protein using a panel of monoclonal antibodies showed that the yeast expressed VP2 was in a conformation different from native VP2 and hence probably unable to elicite an appropriate protective immune response.
Animals↗
High level expression of the envelope glycoprotein (gp53) of bovine viral diarrhoea virus (Singer) and its potential use as diagnostic reagent.
A 1.74-kb cDNA fragment containing the gp53 coding region has been cloned from bovine viral diarrhoea virus (BVDV) strain Singer by reverse transcription polymerase chain reaction (RT-PCR). Sequence analysis indicated that gp53 of BVDV strains Singer, NADL and SD-1 shared extensive sequence homology at both the RNA (85-94%) and protein (82-91%) levels. Nineteen cysteine residues and five potential N-linked glycosylation sites were identified within the sequenced region, all of which were conserved. These observations suggest that although the homology at the nucleotide sequence level may vary, there was strong structural conservation among bovine viral diarrhoea virus envelope proteins. Full-length gp53 was expressed in Escherichia coli as a fusion protein with glutathione-S-transferase (GST). The N-terminal half of gp53 was also synthesised in E. coli as a 28-KDa recombinant protein using the T7 RNA polymerase-directed expression system. Both recombinant proteins were expressed at high levels (approximately 30-50 mg/l). The recombinant proteins were recognised in ELISA and Western blot analyses by polyclonal serum raised against a mixture of BVDV and classical swine fever virus (CSFV). Rabbit antiserum raised against the 28-kDa recombinant protein reacted with different BVDV strains in ELISA and immunofluorescent antibody test, but not with CSFV in the same tests. These results demonstrated that the bacterial recombinant proteins have similar immunological properties to that of the native viral protein and, in conjunction with its homologous antisera, can be useful as diagnostic reagents.
Amino Acid Sequence↗
Evidence for distinct isoforms of 11 beta-hydroxysteroid dehydrogenase in the ovine liver and kidney.
We have previously identified a unique 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) transcript in the ovine kidney. To examine whether this is indicative of a distinct isoform with respect to enzymatic activity, we studied and compared the characteristics of 11 beta-HSD activity in the ovine liver and kidney. 11 beta-HSD activity was determined by a radiometric conversion assay using cortisol and cortisone as physiological substrates. Although in both liver and kidney, the enzyme was localized by subcellular fractionation in the microsomes, the renal 11 beta-HSD displayed distinct characteristics in that it expressed only dehydrogenase activity and utilized almost exclusively NAD as cofactor (the respective activity in the presence of NAD and NADP was 190 +/- 26 and 12 +/- 2 pmol/min/mg protein). By contrast, the liver enzyme contained both dehydrogenase and reductase activities, and displayed preference for NADP and NADPH, respectively. Furthermore, with cortisol as substrate, the kidney 11 beta-HSD had a Km of 68 +/- 7 nM which was over 100 times lower than the hepatic enzyme (8 +/- 1 microM). In addition, the renal 11 beta-HSD activity was inhibited in a dose-dependent fashion by both carbenoxolone, a potent inhibitor of 11 beta-HSD, and the end product cortisone, whereas the liver enzyme showed little inhibition by either substance. In summary, these results provide strong evidence for the existence of distinct isoforms of 11 beta-HSD with respect to enzymatic activity in the ovine liver and kidney. In addition, the characteristics of the kidney enzyme closely resemble those of that described previously in the rabbit renal aldosterone target cells, and thus further demonstrating the presence of an isoform of 11 beta-HSD distinct from the NADP-dependent enzyme purified and cloned from the rat liver.
11-beta-Hydroxysteroid Dehydrogenases↗
Effect of amphotericin B and fluconazole on platelet membrane glycoproteins.
BACKGROUND: Fever, chills, and reduced platelet recovery may result when platelets are transfused simultaneously with amphotericin B. Amphotericin B reportedly increases the pitting of membranes in stored platelets. STUDY DESIGN AND METHODS: The effects of amphotericin B and another antifungal agent, fluconazole, on platelet membrane glycoproteins (GP) were examined by the incubation of split aliquots of fresh and stored platelet concentrates (PCs) with these drugs for 3 days in storage bags. To determine the effect of storage, PCs were stored for 5 days, and aliquots removed on Days 1 through 5 were placed in platelet storage bags with 4 micrograms per mL of amphotericin B for 2 to 6 hours. Membrane glycoprotein expression was assessed by flow cytometry with fluorescein isothiocyanate-labeled monoclonal antibodies (MoAbs) directed against the following antigens: GPIb (CD42b), CD63 (an activation protein), P-selectin (CD62), and GPIIb/IIIa (CD41a). RESULTS: Amphotericin B produced a concentration-dependent decrease in the surface binding of CD42b MoAb with no consistent changes in the binding of CD41a, CD63, or CD62 MoAbs after a 3-day exposure. Stored but not fresh PCs showed decreased binding of MoAb CD42b after a 6-hour exposure to amphotericin B (4 micrograms/mL). Fluconazole produced no changes. When the binding of MoAb CD42b to permeabilized platelets was used to measure total platelet content, amphotericin B (4 micrograms/mL) decreased MoAb CD42b binding to a similar degree in fresh and stored platelets. Inhibition of aggregation to ADP and collagen and ADP and epinephrine was seen in stored but not fresh PCs. CONCLUSION: Therapeutic levels of amphotericin B resulted in partial loss of total platelet GPIb in fresh and stored PCs, but decreased surface expression of platelet membrane GPIb only in stored platelets. This difference between fresh and stored platelets may be related to the limited reservoir of GPIb available for redistribution to the membrane in the previously stored PCs and may account for the decreased recovery of transfused platelets observed in some patients receiving amphotericin B.
Amphotericin B↗
Transfer of an anti-HIV-1 ribozyme gene into primary human lymphocytes.
We reported previously that human CD4+ T cell lines stably expressing a hairpin ribozyme targeted to the human immunodeficiency virus type 1 (HIV-1) U5 leader sequence were resistant to challenge with diverse HIV-1 viral clones and clinical isolates (Yamada et al., 1994). To simulate more closely the in vivo infection process for investigations of anti-HIV-1 ribozyme gene therapy, we developed a system to transfer this ribozyme gene into freshly isolated human peripheral blood lymphocytes (PBLs) using a murine retrovirus vector. Following transduction and G418 selection, human PBLs from multiple donors expressed the ribozyme and resisted challenge by HIV-1 viral clones and clinical isolates, while control vector-transduced PBLs remained fully permissive for HIV-1 infection. No inhibition of an HIV-2 clone lacking the target was seen in ribozyme-expressing PBLs. Ribozyme expression had no effect on viability or proliferation kinetics of the primary lymphocytes. This study is the first demonstration in primary human T cells of resistance to HIV-1 infection conferred by gene transfer. A human clinical trial is in development to test further the safety and efficacy of this ribozyme in PBLs of HIV-1-infected patients in vivo.
Base Sequence↗
The impact of harvest center on quality of marrows collected from unrelated donors.
The total number and distribution of nucleated cells in harvested bone marrow are potentially important determinants of patient outcome following bone marrow transplantation. In order to assess whether marrows collected from predominantly unrelated donors at Georgetown University Medical Center (GUMC) were different in cellular content from marrows collected at harvest centers outside of GUMC, we compared the nucleated cell counts and mononuclear cell subset distribution (CD34, CD3, CD4, CD8, CD19 antigen-positive cell content) of 10 consecutive marrows harvested at GUMC to 10 unrelated donor marrows from outside harvest centers. Significantly higher nucleated cell counts and CD34 antigen-positive cell content and significantly lower CD3 and CD4 antigen-positive T-cell numbers were demonstrated among the marrows harvested at GUMC. These results confirmed significant variability in marrow collection practices between GUMC and 10 different outside harvest centers and suggest that strict adherence to a specific collection procedure, involving small volume marrow aspirations and multiple puncture sites, results in a product with a high number of early hematopoietic progenitor cells and minimal contamination by peripheral blood. These data further suggest the need for careful monitoring of individual unrelated donor marrow collection centers' practices to optimize the quality of the harvested marrow.
Academic Medical Centers↗
Stature estimated from knee height in elderly Japanese Americans.
OBJECTIVE: To validate the use of knee-height-to-stature formulas established on Caucasian subjects to estimate height of Japanese-Americans, ages 60 to 90 years. DESIGN: Survey by measurement of a convenience sample. SUBJECTS: Japanese-American men and women patients, aged 60 years or older, at The Queen's Medical Center during March and April 1992. MEASUREMENTS: Each subject's height (without shoes) was measured in inches by standard height scale and then converted to centimeters. Each subject's knee height was measured using the tool and procedure described by Chumlea et al (Journal of the American Geriatrics Society 1985; 33:116-120). RESULTS: Statures of Japanese-American men and women predicted by the regression models developed on the Hawaii sample were significantly different (P < 0.0001) from the heights predicted by the Caucasian regression model developed by Chumlea and associates (1985). CONCLUSIONS: The statistical models specific to elderly Japanese Americans predicted more precise height approximation than models developed on Caucasians.
Aged↗
Phosphorylation of the duck hepatitis B virus capsid protein associated with conformational changes in the C terminus.
The capsid protein of duck hepatitis B virus (DHBV) is phosphorylated at multiple sites during viral infection. A cluster of sites is located near the C terminus of the 262-amino-acid protein. We have used site-directed mutagenesis to show that three serines and one threonine serve as phosphate acceptor amino acids in the C terminus. An additional six potential phosphate acceptor sites in this region were apparently not utilized. Each serine or threonine that served as a phosphate acceptor was adjacent to a downstream proline, while all six serines that were not acceptors for phosphate residues lacked adjacent downstream prolines. Mutation of the downstream proline to glycine at each site had the same effect as mutating the serine itself, suggesting an SP or TP motif as an essential feature for capsid protein phosphorylation. Phosphorylation at these four sites resulted in complex shifts in electrophoretic mobility in sodium dodecyl sulfate gels of the capsid protein or of a C-terminal peptide containing the phosphorylated sites, suggesting that specific conformations of the C terminus are associated with different combinations of phosphorylated serines. We speculate that distinct functions of the C terminus may be associated with different phosphorylated domains on the intact capsid.
Amino Acid Sequence↗
Multiple functions of capsid protein phosphorylation in duck hepatitis B virus replication.
We have investigated the role of phosphorylation of the capsid protein of the avian hepadnavirus duck hepatitis B virus in viral replication. We found previously that three serines and one threonine in the C-terminal 24 amino acids of the capsid protein serve as phosphorylation sites and that the pattern of phosphorylation at these sites in intracellular viral capsids is complex. In this study, we present evidence that the phosphorylation state of three of these residues affects distinct steps in viral replication. By substituting these residues with alanine in order to mimic serine, or with aspartic acid in order to mimic phosphoserine, and assaying the effects of these substitutions on various steps in virus replication, we were able to make the following inferences. (i) The presence of phosphoserines at residues 245 and 259 stimulates DNA synthesis within viral nucleocapsids. (ii) The absence of phosphoserine at residue 257 and at residues 257 and 259 stimulates covalently closed circular DNA synthesis and virus production, respectively. (iii) The presence of phosphoserine at position 259 is required for initiation of infection. The results implied that both phosphorylated and nonphosphorylated capsid proteins were necessary for a nucleocapsid particle to carry out all its functions in virus replication, explaining why differential phosphorylation of the capsid protein occurs in hepadnaviruses. Whether these differentially phosphorylated proteins coexist on the same nucleocapsid, or whether the nucleocapsid acquires sequential functions through selective phosphorylation and dephosphorylation, is discussed.
Alanine↗