Electric-field-dependent intersubband transition via optical phonons in a doped-thin-layer inserted quantum-well structure.
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Journal Article↗
Biomedical subjects
Y Guo
Publications and source records attributed to Y Guo.
Embolism from the aortic arch in patients with cerebral ischemia.
The pathogenic role of aortic arch atherosclerosis (AAA) in embolic stroke is not well understood. We investigated, prospectively, the prevalence and severity of AAA in patients with embolic stroke to ascertain its role as a risk factor for cerebral ischemia. We examined 100 consecutive patients who had experienced acute symptoms due to cerebral ischemia. Clinical examination, electrocardiogram, x-ray, ultrasound examination of craniocervical arteries, transesophageal echocardiography (TEE), cranial computerized tomography, and magnetic resonance imaging were undertaken. Seventy-five patients showed evidence of AAA; 34 patients had moderate to severe (> 5 mm thickening) AAA. Age was positively related to the severity of AAA, as were smoking, coronary heart disease, diabetes mellitus, internal carotid artery (ICA) occlusive disease, and embologenic heart disease. Hypertension, which was evident in 52 patients, did not distinguish those cases showing AAA. Twelve patients showed evidence of high-degree ICA stenosis on the symptomatic side, although the extent of ICA stenosis and AAA were unrelated. A cardiac source of emboli was found in 28 patients. AAA was found to be the probable source for embolic stroke in 14 patients. These data indicate that aortic arch atherosclerosis is an important source of cerebral emboli which may increase the risk for ischemic stroke. Furthermore, we suggest that TEE examination of the aortic arch may be important for the diagnosis of AAA and ultimately for the prophylactic treatment of severe cerebral ischemia.
Adult↗
Fibroblast growth factor-1 stimulation of quiescent NIH 3T3 cells increases G/T mismatch-binding protein expression.
Polypeptide growth factors promote cell-cycle progression in part by the transcriptional activation of a diverse group of specific genes. We have used an mRNA differential-display approach to identify several fibroblast growth factor (FGF)-1 (acidic FGF)-inducible genes in NIH 3T3 cells. Here we report that one of these genes, called FGF-regulated (FR)-3, is predicted to encode G/T mismatch-binding protein (GTBP), a component of the mammalian DNA mismatch correction system. The murine GTBP gene is transiently expressed after FGF-1 or calf serum treatment, with maximal mRNA levels detected at 12 and 18 h post-stimulation. FGF-1-stimulated NIH 3T3 cells also express an increased amount of GTBP as determined by immunoblot analysis. These results indicate that elevated levels of GTBP may be required during the DNA synthesis phase of the cell cycle for efficient G/T mismatch recognition and repair.
3T3 Cells↗
CD40L is important for induction of, but not response to, costimulatory activity. ICAM-1 as the second costimulatory molecule rapidly up-regulated by CD40L.
The CD40 ligand (CD40L):CD40 interaction plays an important role in the activation of both T and B cells. However, the mechanisms by which this interaction is involved in activation of T cells is still unclear. Here we show that CD40L is not essential for T cell response to TCR engagement if the APC have costimulatory activity, although it is essential for T cell-mediated induction of such costimulatory activity. To determine the molecular basis of this activity, we have produced three mAbs that appear to recognize the costimulatory molecules rapidly induced by CD40L. Two of them recognize CD44H, which we showed to have CD28-independent costimulatory activity for T cells. The molecule recognized by the remaining mAb is hereby identified as ICAM-1. Furthermore, ICAM-1-mediated costimulation is likely to serve for a function similar to that mediated by the B7:CD28 interaction, as targeted mutation of CD28 renders T cell responses to Con A more dependent on ICAM-1.
Animals↗
Hydrolytically stable amino-silica glass coating material for manipulation of the electroosmotic flow in capillary electrophoresis.
A hydrolytically stable amino-silica glass coating material was fabricated inside fused-silica capillaries, using sol-gel technology. Aminopropyltriethoxysilane was used as the precursor in the glass formation process. The net charge at the surface of the coating material depends on the degree of protonation of the amino groups and the degree of ionization of the silanol groups, thus enabling manipulation of the magnitude and direction of the electroosmotic flow (EOF). At low pH (< 6.0), the coating bears a net positive charge, which results in an electroosmotic flow from the cathode toward the anode and minimizes the wall-solute interactions of basic species. At high pH (> 6.5), the coating surface bears a net negative charge and the coated capillary behaves like an uncoated one, having an EOF in the cathodic direction. The amino-silica glass coating has also been shown to be extremely stable under both acidic and basic conditions. The reproducibility of the electroosmotic mobility of five different capillaries was found to be 7% R.S.D. The utility of the material is shown with the separation of basic proteins, peptides and basic compounds.
Acids↗
Identification of a costimulatory molecule rapidly induced by CD40L as CD44H.
The interaction between CD40 ligand and CD40 is critical for activation of T and B cells in vivo. We have recently demonstrated that this interaction rapidly induces a novel costimulatory activity distinct from B7 and independent of CD28. To study the molecular basis of the costimulatory activity, we have produced a novel monoclonal antibody, TM-1, that binds an 85-kilodalton costimulatory molecule rapidly induced by CD40L. Expression cloning reveals that TM-1 binds CD44H. CD44H expressed on Chinese hamster ovary cells has potent costimulatory activity for clonal expansion of T cells isolated from both wild-type mice and these with a targeted mutation of CD28. Thus, CD44H costimulates T cell proliferation by a CD28-independent mechanism. These results revealed that CD44H is a costimulatory molecule rapidly induced by CD40L.
Animals↗
Characterisation of vha26, the Drosophila gene for a 26 kDa E-subunit of the vacuolar ATPase.
A Drosophila melanogaster gene and cDNA for the E-subunit of the V-ATPase were characterised. The deduced product has 226 amino acids and a molecular mass of 26.1 kDa. The gene is a single copy at 83B1-4 on chromosome 3R. The coding sequence is punctuated by three introns which do not align with those in Neurospora. The gene is ubiquitously expressed as an mRNA of 2.3 kb. but at lower levels in pupae.
Amino Acid Sequence↗
Compartmental organization of styloglossus and hyoglossus motoneurons in the hypoglossal nucleus of the rat.
Surgical techniques were used to isolate the extrinsic bellies of the styloglossus and hyoglossus muscles from the body of the tongue for cholera toxin HRP injection. An average of 53 styloglossus and 121 hyoglossus motoneurons in the dorsal subdivision of the hypoglossal nucleus were demonstrated using tetramethyl benzidine histochemistry. Styloglossus motoneurons were restricted to the rostral 25% of the nucleus while hyoglossus motoneurons occupied other regions of the dorsal nucleus.
Animals↗
Vascular incorporation of alpha-tocopherol prevents endothelial dysfunction due to oxidized LDL by inhibiting protein kinase C stimulation.
Excess vascular oxidative stress has been linked to impaired endothelium-dependent arterial relaxation in hypercholesterolemia. alpha-Tocopherol (AT) preserves endothelial function in hypercholesterolemia although the mechanism(s) for this protective effect is (are) not known. We examined the tissue-specific effects of AT on oxidized LDL (ox-LDL)-mediated endothelial dysfunction in male New Zealand White rabbits. Animals consumed chow deficient in (< 10 IU/kg) or supplemented with (1,000 IU/kg) AT for 28 d. Exposure of thoracic aortae from AT-deficient animals to ox-LDL (0-500 microg/ml) for 4 h produced dose-dependent inhibition of acetylcholine-mediated relaxation (P < 0.05) while vessels derived from animals consuming AT were resistant to ox-LDL-mediated endothelial dysfunction. Animals consuming AT demonstrated a 100-fold increase in vascular AT content and this was strongly correlated with vessel resistance to endothelial dysfunction from ox-LDL (R = 0.67; P = 0.0014). These results were not explained by an effect of AT on ox-LDL-mediated cytotoxicity by LDH assay or scanning electron microscopy. Vascular incorporation of AT did produce resistance to endothelial dysfunction from protein kinase C stimulation, an event that has been implicated in the vascular response to ox-LDL. Human aortic endothelial cells loaded with AT also demonstrated resistance to protein kinase C stimulation by both phorbol ester and ox-LDL. Thus, these data indicate that enrichment of vascular tissue with AT protects the vascular endothelium from ox-LDL-mediated dysfunction, at least in part, through the inhibition of protein kinase C stimulation. These findings suggest one potential mechanism for the observed beneficial effect of AT in preventing the clinical expression of coronary artery disease that is distinct from the antioxidant protection of LDL.
Analysis of Variance↗
Presence of MHC-I and B-7 molecules in rat and human glioma cells expressing antisense IGF-I mRNA.
Tumor cells frequently express the insulin-like growth factor I (IGF-I). Recently we demonstrated that rat glioma cells when transfected with a vector encoding antisense IGF-I cDNA lost tumorigenicity and induced a tumor specific immune response involving CD8+ lymphocytes. Here we show that the cultured transfected cell lines, rat C-6 glioma, human primary glioma and mouse teratocarcinoma, expressed an increased level of MHC-I and of co-signaling B-7 molecules. This increased expression of MHC-I and B-7, demonstrated by 51Cr release complement dependent cytoxicity assay and by immunostaining flow cytometry analysis, could contribute to the final immune recognition of glioma immunogenicity.
Animals↗
The Drosophila melanogaster gene vha14 encoding a 14-kDa F-subunit of the vacuolar ATPase.
A Drosophila melanogaster (Dm) cDNA (vha14) encoding the 14-kDa F-subunit of the vacuolar H(+)-ATPase (V-ATPase) has been cloned via homology with the corresponding Manduca sexta (Ms) gene. Its deduced translation product is a 124-amino-acid polypeptide sharing 90% identity with the Ms polypeptide and 50% identity with an analogous polypeptide of Saccharomyces cerevisiae, and a more distant similarity to a subunit of the Na(+)-transporting ATPase of Enterococcus hirae. Homology was also found with expressed sequence tags from man, Arabidopsis thaliana, Caenorhabditis elegans and C. briggsiae, Oryza sativa and Plasmodium falciparum, indicating that the subunit is phylogenetically conserved. The Dm gene (vha14) is present as a single copy at cytological position 52B on the second chromosome, and gives rise to an mRNA species of 0.65 kb. Expression of the latter shows relatively little variation during development, or between adult head, thorax and abdomen, suggesting that the F-subunit is a relatively ubiquitous component of the V-ATPase.
Adenosine Triphosphatases↗
Identification of a murine TEF-1-related gene expressed after mitogenic stimulation of quiescent fibroblasts and during myogenic differentiation.
Fibroblast growth factor (FGF)-1 binding to cell surface receptors stimulates an intracellular signaling pathway that ultimately promotes the transcriptional activation of specific genes. We have used a mRNA differential display method to identify FGF-1-inducible genes in mouse NIH 3T3 fibroblasts. Here, we report that one of these genes, FGF-regulated (FR)-19, is predicted to encode a member of the transcriptional enhancer factor (TEF)-1 family of structurally related DNA-binding proteins. Specifically, the deduced FR-19 amino acid sequence has approximately89, 77, and 68% overall identity to chicken TEF-1A, mouse TEF-1, and mouse embryonic TEA domain-containing factor, respectively. Gel mobility shift experiments indicate that FR-19, like TEF-1, can bind the GT-IIC motif found in the SV40 enhancer. The FR-19 gene maps in the distal region of mouse chromosome 6, and analysis of several FR-19 cDNA clones indicates that at least two FR-19 isoforms may be expressed from this locus. FGF-1 induction of FR-19 mRNA expression in mouse fibroblasts is first detectable at 4 h after FGF-1 addition and is dependent on de novo RNA and protein synthesis. FGF-2, calf serum, platelet-derived growth factor-BB, and phorbol 12-myristate 13-acetate can also induce FR-19 mRNA levels. We have also found that FR-19 mRNA expression increases during mouse C2C12 myoblast differentiation in vitro. The FR-19 gene is expressed in vivo in a tissue-specific manner, with a relatively high level detected in lung. These results indicate that increased expression of a TEF-1-related protein may be important for both mitogen-stimulated fibroblast proliferation and skeletal muscle cell differentiation.
3T3 Cells↗
Recombinant PSP94 (prostate secretory protein of 94 amino acids) demonstrates similar linear epitope structure as natural PSP94 protein.
PSP94 has the potential to be a useful diagnostic marker and therapeutic agent in prostate cancer. Recently, different immunoassay systems for quantitative analysis of PSP94 in clinical samples have been developed, but the epitope structure of PSP94 protein has not been elucidated. In this study, we report an Escherichia coli expression system for recombinant GST-PSP94 fusion protein. GST-PSP94 contains antigenic determinants similar to natural PSP94 protein (determined both by Western blotting experiments and by ELISA) and can be used to study the structure of natural PSP94 antigen. Since GST-PSP94 was expressed in E. coli and purification involved a denaturing process, we propose that the epitope structure of PSP94 is linear and largely dependent on the primary amino acid sequence, rather than conformational structure. This hypothesis was supported by reciprocal competition in ELISA among natural, GST-PSP94 fusion protein, and purified recombinant PSP94 protein. The results demonstrate that the various forms of PSP94 can compete with each other in binding to rabbit PSP94 polyclonal antibody, although the natural PSP94 has a slightly higher affinity. When natural and recombinant PSP94 protein were denatured in vitro with urea and alkali, no effect on the binding to antibody was found. The epitope activity of natural PSP94 was also shown to be resistant to the treatment of detergent and reducing agent. The location of one of the linear epitopes recognized by the PSP94 antibody was determined to be in the N-terminus by using two synthetic peptides representing N- and C-terminal sequences. Competitive ELISA between the N-terminal peptide and PSP94 protein indicate that both natural and GST-PSP94 have similar immunoactive N-termini.
Animals↗
Fibroblast growth factor-1-inducible gene FR-17 encodes a nonmuscle alpha-actinin isoform.
Polypeptide growth factor binding to cell surface receptors activates a cytoplasmic signaling cascade that ultimately promotes the expression of specific nuclear genes. As an approach to investigate the molecular mechanism of fibroblast growth factor (FGF)-1 mitogenic signaling, we have begun to identify and characterize FGF-1-inducible genes in murine NIH 3T3 cells. Here we report that one of these genes, termed FGF-regulated (FR)-17, is predicted to encode a nonmuscle isoform of alpha-actinin, an actin cross-linking protein found along microfilaments and in focal adhesion plaques. FGF-1 induction of alpha-actinin mRNA expression is first detectable at 2 h after mitogen addition and is dependent on the novo RNA and protein synthesis. Maximal alpha-actinin mRNA expression, corresponding to an approximately nineteenfold level of induction, is present after 12 h of FGF-1 stimulation. Western blot analysis indicated that FGF-1-stimulated cells also produce an increased amount of alpha-actinin protein. The FGF-1-related mitogen FGF-2, calf serum, several of the polypeptide growth factors present in serum, and the tumor promoter phorbol myristate acetate can also induce alpha-actinin mRNA expression. Finally, nonmuscle alpha-actinin mRNA is expressed in vivo in a tissue-specific manner, with relatively high levels detected in adult mouse intestine and kidney. These results indicate that nonmuscle alpha-actinin is a serum-, polypeptide growth factor-, and tumor promoter-inducible gene in mouse fibroblasts.
3T3 Cells↗
Restoration of responsiveness to phorbol ester by reconstitution of a functional Na/K/Cl cotransporter in cotransporter-deficient BALB/c 3T3 cells.
Previous studies in this laboratory have implicated the membrane transport protein Na/K/Cl cotransporter (NKCC1) as an important component of the signaling pathways activated by phorbol esters in BALB/c 3T3 cells. The NKCC1 protein functions as a Na/K/Cl cotransporter in BALB/c 3T3 cells and many other cell types. Loss of NKCC1 function has been associated with loss of mitogenic responsiveness to phorbol ester. Here we report that expression of a cloned NKCC1 cDNA fused to a tetracycline-regulated promoter in BALB/c 3T3 cells deficient in Na/K/Cl cotransport activity (clone E12a cells) restored cotransport function. Compared with parental cotransport-deficient cells, transfected clones expressing the exogenous NKCC1 gene responded like typical BALB/c 3T3 cells to 12-O-tetradecanoylphorbol-13-acetate: loop diuretic-sensitive 86Rb+ flux was inhibited, cell volume was decreased, and cell growth was stimulated. These results support our previous conclusion that the loss of responsiveness of E12a cells to phorbol ester is caused by mutation of the endogenous NKCC1 gene.
3T3 Cells↗
Phenotyping of esterase D and acid phosphatase by rapid isoelectric focusing on PhastSystem.
A rapid isoelectric focusing method on PhastSystem was applied to investigate the distribution of esterase D (ESD) and acid phosphatase (ACP) phenotypes in 152 and 112 unrelated healthy donors, respectively, from the Han population in Beijing. Laboratory-made gels with a pH range of 5.0-7.0 and 5.0-8.0 were used for analysis of ESD and ACP, respectively, with 1 microliter sample loading. The running time was 30-40 min. Gene frequencies for ESD were 0.6809 for ESD*1 and 0.3191 for ESD*2, (sigma chi 2 = 0.8586 and P > or = 0.50); gene frequencies of ACP were 0.2009 for ACP*A, 0.7991 for ACP*B, (sigma chi 2 = 1.7892 and P > 0.20), with good agreement between the observed and the expected values.
Acid Phosphatase↗
Subtyping of group-specific component and protease inhibitor by rapid isoelectric focusing on PhastSystem.
A rapid method on PhastSystem was used to investigate the distribution of group-specific component (GC) and protease inhibitor (PI) subtypes and their gene frequencies from 190 unrelated healthy donors of the Han population in Beijing. Laboratory-made gels (pH 4.5-5.4 and pH 4.2-4.9) were used for analysis of GC and PI, respectively. Sample loading was 1.5 microliters. The separation and visualization time was 0.5 h in each. Gene frequencies were as follows: GC*1F = 0.4891, GC*1S = 0.2432, GC*2 = 0.2678; rare GC variants were discovered in seven cases. The results for PI were: PI*M1 = 0.7542, PI*M2 = 0.1808, PM*M3 = 0.0650. Good agreement between the observed and expected values in both GC and PI subtyping (for GC, sigma chi 2 = 1.4043, 0.7 < P < 0.8; for PI, sigma chi 2 = 1.1233, 0.7 < P < 0.8) was obtained.
Gene Frequency↗
Purification of apolipoprotein H by polyethylene glycol precipitation.
A new method of polyethylene glycol precipitation followed by heparin affinity chromatography was established to purify apolioprotein H (Apo H, beta 2-glycoprotein I). This method is simple and effective and yields more harvest of Apo H (3-4 mg Apo H from 100 ml fetal bovine serum) than the current HClO4 extraction method. There are notable differences between Apo H purified by the polyethylene glycol method [Apo H (PEG)] and Apo H purified by the HClO4 method [Apo H (HClO4)] in respects of their SDS electrophoresis characteristics, circular dichroism spectroscopy, and isoelectric focusing graph. It is concluded that the strong acid HClO4 treatment may induce some disordered structure in Apo H molecule resulting in the lowering of molecular weight and pIs. Apo H (PEG) retains more integrated structure which may be related to its bioactivity.
Apolipoproteins↗