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N Huang

Publications and source records attributed to N Huang.

At least 109 records · Page 6Linked to original sources
PubMed1993

Identification of immature and mature myeloma cells in the bone marrow of human myelomas.

With regard to the expression of adhesion molecules, human myeloma cells freshly isolated from bone marrow were heterogeneous. By two-color analysis with anti-VLA-5 antibody (PE staining) and FITC-labeled anti-CD38 antibody, we found all myeloma cells located at CD38-strong positive (CD38++) fraction and identified two subpopulations among these myeloma cells: CD38++ VLA-5-(VLA-5-) myeloma cells and CD38++ VLA-5+ (VLA-5+) myeloma cells. To clarify the biologic character of these two subpopulations, the morphology, in vitro proliferative activity and in vitro M-protein secretion were examined in each fraction isolated by the purification procedure or a cell sorter. Morphologic examination showed that VLA-5- myeloma cells were mostly immature or plasmablastic and VLA-5+ cells were mature myeloma cells. Furthermore, VLA-5- myeloma cells proliferated markedly in vitro and responded to interleukin 6 (IL-6), a growth factor for myeloma cells, while VLA-5+ myeloma cells showed very low uptakes of 3H-thymidine and no responses to IL-6 but secreted higher amounts of M-protein (immunoglobulin) in vitro significantly. Therefore, we could clarify here heterogeneity of human myeloma cells in the bone marrow with regard to the expression of VLA-5, one of integrin adhesion molecules; VLA-5- myeloma cells were proliferative immature cells and VLA-5+ cells were mature myeloma cells.

ADP-ribosyl Cyclase↗
PubMed1993

Phenotypic difference of normal plasma cells from mature myeloma cells.

We have recently shown that two-color analysis with fluorescein isothiocyanate (FITC)-anti-CD38 antibody could clearly distinguish myeloma cells (plasma cells) from other hematopoietic cells in the bone marrow. Myeloma cells (plasma cells) alone were located at CD38strong positive (++) fractions. To further distinguish normal plasma cells from mature myeloma cells phenotypically, we examined immunophenotypes of normal plasma cells and myeloma cells by two-color flow cytometry with FITC-anti-CD38 antibody and phycoerythrin staining with antibody to VLA-4, MPC-1, CD44, CD56, CD19, CD20, CD24, or CD10. Normal plasma cells were all VLA-4+VLA-5+MPC-1+CD44+ CD19+CD56- in the bone marrows from seven healthy donors, tonsils from four patients with chronic tonsillitis, a spleen from one patient with idiopathic thrombocytopenic purpura, and lymph nodes from two patients with chronic lymphadenitis, respectively. On the other hand, mature myeloma cells (12 of 20 cases), VLA-4+VLA-5+MPC-1+, were all CD19- and most of them CD56+, and there were no myeloma cells with the CD19+CD56- phenotype in the 20 cases of myelomas we tested. Thus, as for the expression of CD19 and CD56, normal plasma cells from various tissues are all CD19+CD56-, whereas no myeloma cells have the CD19+CD56- phenotype. According to this finding, we investigated the expression of CD19 and CD56 on plasma cells (CD38++ fractions) in monoclonal gammopathy of undetermined significance (MGUS). Both CD19+CD56- and CD19-DC56+ plasma cells were found in all five cases of MGUS we tested, suggesting that MGUS consists of phenotypically normal plasma cells and myeloma cells. Therefore, it is reasoned that phenotypic analysis of plasma cells with anti-CD19 and anti-CD56 antibodies can distinguish normal plasma cells from malignant plasma cells (myeloma cells), and can detect malignant plasma cells even in MGUS or premyeloma states.

Aged↗
PubMed1993

Metabolic regulation of alpha-amylase gene expression in transgenic cell cultures of rice (Oryza sativa L.).

Expression of two genes in the alpha-amylase gene family is controlled by metabolic regulation in rice cultured cells. The levels of RAmy3D and RAmy3E mRNAs in rice cultured cells are inversely related to the concentration of sugar in the culture medium. Other genes in the rice alpha-amylase gene family have little or no expression in cultured cells; these expression levels are not controlled by metabolic regulation. A RAmy3D promoter/GUS gene fusion was metabolically regulated in the transgenic rice cell line 3DG, just as the endogenous RAmy3D gene is regulated. An assay of GUS enzyme activity in 3DG cells demonstrated that RAmy3D/GUS expression is repressed when sugar is present in the culture medium and induced when sugar is removed from the medium. The 942 bp fragment of the RAmy3D promoter that was linked to the coding region of the GUS reporter gene thus contains all of the regulatory sequences necessary for metabolic regulation of the gene.

Base Sequence↗
PubMed1993

Overexpression of a truncated growth hormone receptor in the sex-linked dwarf chicken: evidence for a splice mutation.

Sex-linked dwarfism in chickens is a form of GH resistance that resembles the Laron syndrome in humans. The dwarfism found in chickens is due to a mutant gene (dw) carried on the sex chromosome. The homozygous dwarf (dwdw) chicken is characterized by reductions in stature and plasma insulin-like growth factor-I (IGF-I) levels. Despite the absence of hepatic GH-binding activity, Southern blot analysis shows that there is no gross structural change in the gene for the GH receptor (GHR) in this strain of dwdw chicken. GH-dependent IGF-I production can be restored in cultured dwdw hepatocytes after transfection and transient expression of a chicken GHR (cGHR) cDNA, indicating that other factors that participate in GH-mediated IGF-I synthesis are intact. Northern blot analysis of liver, muscle, fat, and pituitary RNA from normal (DwDw) chickens shows a major transcript of 4.3 kilobases (kb) and three minor transcripts (0.8, 1.7, and 3.2 kb), which correspond to the cGHR. In contrast, the 0.8-kb transcript is the major cGHR transcript expressed in these tissues from dwdw chickens. Northern blot analysis with domain-specific probes shows that the 0.8-kb transcript in DwDw and dwdw liver contains only a small portion of the extracellular domain of the cGHR. A cDNA clone encoding this transcript has been isolated from a liver library prepared from a normal chicken.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Differential recovery of mRNA transcripts using acid organic extraction techniques: quantification of abl mRNA abundance in the blowfly, Calliphora erythrocephala.

A commonly used RNA isolation technique that employs a single-step acid phenol-chloroform extraction (Chomczynski and Sacchi, 1987) produces a different distribution pattern of C. erythrocephala c-abl (Ceabl) transcripts following Northern blot analysis than methods that rely on phenol-chloroform extraction at basic pH (Jowett, 1986). Only Ceabl transcripts of 10.5 kb and 6.5 kb are recovered, while Ceabl transcripts of 9 kb and 4.4 kb are lost, when acidic phenol-chloroform methods are used. All tested extraction methods which do not rely on phenol-chloroform extraction under acidic conditions can recover Ceabl transcripts of 10.5 kb, 9 kb, 6.5 kb and 4.4 kb. The reason for this discrepancy is apparently due to differential loss of mRNA at the phenol phase and/or interphase boundary during the acidic extractions.

Acids↗
PubMed1992

Classification and evolution of alpha-amylase genes in plants.

The DNA sequences for 17 plant genes for alpha-amylase (EC 3.2.1.1) were analyzed to determine their phylogenetic relationship. A phylogeny for these genes was obtained using two separate approaches, one based on molecular clock assumptions and the other based on a comparison of sequence polymorphisms (i.e., small and localized insertions) in the alpha-amylase genes. These polymorphisms are called "alpha-amylase signatures" because they are diagnostic of the gene subfamily to which a particular alpha-amylase gene belongs. Results indicate that the cereal alpha-amylase genes fall into two major classes: AmyA and AmyB. The AmyA class is subdivided into the Amy1 and Amy2 subfamilies previously used to classify alpha-amylase genes in barley and wheat. The AmyB class includes the Amy3 subfamily to which most of the alpha-amylase genes of rice belong. Using polymerase chain reaction and oligonucleotide primers that flank one of the two signature regions, we show that the AmyA and AmyB gene classes are present in approximately equal amounts in all grass species examined except barley. The AmyB (Amy3 subfamily) genes in the latter case are comparatively underrepresented. Additional evidence suggests that the AmyA genes appeared recently and may be confined to the grass family.

Base Sequence↗
PubMed1992

RAmy2A; a novel alpha-amylase-encoding gene in rice.

The structure and expression of the alpha-amylase-encoding gene, RAmy2A, are described. This only representative of the Amy2 subfamily in rice differs from other cereal alpha-amylase-encoding genes in several respects. It contains the largest introns of all the cereal alpha-amylase-encoding genes examined to date. Moreover, the second of three introns in this gene contains a long inverted repeat sequence that can potentially form a large and stable stem-loop structure in the unspliced RNA transcript. Finally, RAmy2A is constitutively expressed at very low levels in germinated seeds, root, etiolated leaves, immature seeds and callus. This is in marked contrast to the Amy2 genes of wheat and barley which are highly expressed in the aleurone layer of the germinated seeds.

Amino Acid Sequence↗
PubMed1992

Structure of a rice beta-glucanase gene regulated by ethylene, cytokinin, wounding, salicylic acid and fungal elicitors.

A rice beta-glucanase gene was sequenced and its expression analyzed at the level of mRNA accumulation. This gene (Gns1) is expressed at relatively low levels in germinating seeds, shoots, leaves, panicles and callus, but it is expressed at higher levels in roots. Expression in the roots appears to be constitutive. Shoots express Gns1 at much higher levels when treated with ethylene, cytokinin, salicylic acid, and fungal elicitors derived from the pathogen Sclerotium oryzae or from the non-pathogen Saccharomyces cereviseae. Shoots also express Gns1 at higher levels in response to wounding. Expression in the shoots is not significantly affected by auxin, gibberellic acid or abscisic acid. The beta-glucanase shows 82% amino acid similarity to the barley 1,3;1,4-beta-D-glucanases, and from hybridization studies it is the beta-glucanase gene in the rice genome closest to the barley 1,3;1,4-beta-glucanase EI gene. The mature peptide has a calculated molecular mass of 32 kDa. The gene has a large 3145 bp intron in the codon for the 25th amino acid of the signal peptide. The gene exhibits a very strong codon bias of 99% G + C in the third position of the codon in the mature peptide coding region, but only 61% G + C in the signal peptide region.

Amino Acid Sequence↗
PubMed1992

[Assay of genomic DNA homology among strains of different virulent leptospira by DNA hybridization].

Nick translation labelling technique was applied to the preparation of two 32P labelled genomic DNA probes from L. interrogans serovar Lai strain 017 and Leptonema illini strain 3055, respectively. Dot-blotting and Southern-blotting with DNA of five strains leptospira from different genus and species were performed. The results showed that certain differences among the L. interrogans, L. biflexa and Leptonema illini could be detected by endonuclease assay. L. interrogans strain 017 with L. biflexa strain Patoc I and Leptonema illini 3055 strain exhibited very little homology. L. interrogans strains 017, 601, and 245 from different serogroup and serovar had a high degree of homology. Leptonema illini strain 3055 showed little homology with L. interrogans and L. biflexa. Therefore DNA hybridization may be used as a tool for the identification and classification of leptospira.

Blotting, Southern↗
PubMed1991

Characterization of an alpha-amylase multigene cluster in rice.

Rice genomic clones containing eight different alpha-amylase genes have been previously classified into five groups based on DNA hybridization studies and restriction site mapping. This report describes the clustering of three Group 3 genes (RAmy3A, RAmy3B and RAmy3C) within 28 kb of genomic DNA. The genes are separated from each other by about 5 kb and transcribed in the same direction. At the protein level, RAmy3B and RAmy3C are 95% homologous while each is 78% homologous to RAmy3A. All three genes have relatively small introns in the first and third positions. RAmy3A; however, has an additional 409 bp intron in the second intron insertion site. Nucleotide sequence comparisons of the coding and 3' flanking regions suggest that clustering of the RAmy3 genes occurred by gene duplication resulting from unequal crossing-over at repetitive sequences. A comparison of the 5' flanking regions revealed several sequences that may be involved in transcription. Expression of RAmy3B/C first appears in the germinating seed after two days and at a higher level after four days. Quantitative primer extension analysis indicates that RAmy3B and RAmy3C contribute 25% and 75%, respectively, of the transcripts from this cluster at four days of germination. No primer extension band specific to RAmy3A transcripts could be detected at this time point. However, RAmy3A PCR products could be amplified from RNA isolated from embryo-derived callus tissue.

Base Sequence↗
PubMed1991

Homotypic cell aggregations of human myeloma cells with ICAM-1 and LFA-1 molecules.

Some myeloma cells freshly isolated from bone marrow aspirates in human myelomas and some myeloma cell lines formed spontaneous cell aggregations in vitro (homotypic cell aggregations). In order to clarify the surface molecules involved in homotypic cell aggregations and physiological roles of these cell aggregations, we investigated the expressions of intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) on 20 samples of freshly isolated myeloma cells and three myeloma cell lines and the effect of anti-ICAM-1 and anti-LFA-1 alpha antibodies on myeloma cell proliferation in vitro. All myeloma cells that we tested expressed ICAM-1 on their surface. Among them, myeloma cells that strongly coexpressed LFA-1 alpha, formed homotypic cell aggregates in vitro. These spontaneous cell aggregations were completely released by adding either anti-ICAM-1 or anti-LFA-1 alpha antibody. During short-term culture, spontaneous proliferation of myeloma cells in vitro and their proliferative responses to recombinant interleukin-6 (rIL-6) were not affected by pretreatment of myeloma cells with anti-ICAM-1 or anti-LFA-1 alpha antibody. Therefore these data suggest that homotypic cell aggregation of myeloma cells is mediated by ICAM-1 and LFA-1 molecules, but myeloma cell proliferation may not be modulated by these adhesion molecules during short-term cultures.

Antigens, CD↗
PubMed1990

The isolation and characterization of a barley 1,3-1,4-beta-glucanase gene.

The barley gene encoding isozyme I of 1,3-1,4-beta-glucanase was isolated and sequenced. The 6260-bp region sequenced included 1885 bp of the 5'-flanking region, the entire coding region, an intron of 2490 bp, and 792 bp of the 3'-flanking region. The 1,3-1,4-beta-glucanase mRNA was found to be regulated at the level of RNA accumulation by both gibberellins (positively) and abscisic acid (negatively) in barley aleurones. The mRNA for isozyme II preferentially accumulated (70%) relative to the mRNA for isozyme I (30%) in poly(A)-rich RNA isolated from material including both the aleurone and the scutellum tissues. The gene family encoding 1,3-1,4-beta-glucanase enzymes in barley was found to be comprised of two closely related genes, isozymes I and II, as well as several related sequences that could be identified by Southern blot analysis. The nucleotide sequence for the 5' untranslated leader and the coding region for the signal peptide of the isozyme II transcript were determined from a cDNA produced by the polymerase chain reaction. The structure of the protein encoded by the isozyme I gene is also discussed.

Abscisic Acid↗
PubMed1990

Structural organization and differential expression of rice alpha-amylase genes.

Rice alpha-amylases are encoded by a multigene family that has previously been classified into 5 hybridization groups. DNA sequence and Southern blot analysis identified three genes (RAmy1A, RAmy1B and RAmy1C) in Group 1 with DNA sequence identity of at least 90%. Hybridization Group 2 is represented by only one gene, RAmy3D, which is identical to a previously characterized cDNA, pOS137. RAmy3D is physically linked to the sole representative of Group 5, RAmy3E. The identity between these two genes is 81.4% in the coding region but less than 50% in the 5' and 3' flanking regions. Northern blot analysis and RNA-PCR were used to detect the expression of alpha-amylase genes in various tissues. Alpha-amylase mRNA was abundant in germinating seeds and callus. Some genes were also expressed at much lower levels in roots, young leaves and immature seeds. RAmy1A and RAmy3E were expressed in all tissues while RAmy3D was expressed in all tissues except the immature seeds. RAmy1B was weakly expressed only in callus. RAmy1A transcript was most abundant in the germinating seeds, while RAmy3D and RAmy3E transcripts were most abundant in callus and immature seeds, respectively.

Amino Acid Sequence↗
PubMed1990

Classification and characterization of the rice alpha-amylase multigene family.

To establish the size and organization of the rice alpha-amylase multigene family, we have isolated 30 alpha-amylase clones from three independent genomic libraries. Partial characterization of these clones indicates that they fall into 5 hybridization groups containing a total of 10 genes. Two clones belonging to the Group 3 hybridization class have more than one gene per cloned fragment. The nucleotide sequence of one clone from Group 1, lambda OSg2, was determined and compared to other known cereal alpha-amylase sequences revealing that lambda OSg2 is the genomic analog of the rice cDNA clone, pOS103. The rice alpha-amylase genes in Group 1 are analogous to the alpha-Amy1 genes in barley and wheat. lambda OSg2 contains sequence motifs common to most actively transcribed genes in plants. Two consensus sequences, TAACAAGA and TATCCAT, were found in the 5' flanking regions of alpha-amylase genes of rice, barley and wheat. The former sequence may be specific to alpha-amylase gene while the latter sequence may be related to a 'CATC' box found in many plant genes. Another sequence called the pyrimidine box (TCCTTTTTC) was found in the alpha-amylase genes as well as other genes regulated by gibberellic acid (GA). Comparisons based on amino acid sequence alignment revealed that the multigene families in rice, barley and wheat shared a common ancestor which contained three introns. Some of the descendants of the progenitor alpha-amylase gene appear to have lost the middle intron while others maintain all three introns.

Amino Acid Sequence↗
PubMed1990

The alpha-amylase genes in Oryza sativa: characterization of cDNA clones and mRNA expression during seed germination.

Two cDNA clones, pOS103 and pOS137, were isolated which code for distinct alpha-amylase isozymes in germinating rice seeds. Sequence analysis indicated that the clones encode polypeptides of approximately 48 kDa, both of which possess a signal peptide involved in directing secretion of the protein. Comparison of the two rice alpha-amylase amino acid sequence showed that they are 76% similar to each other, while showing 85% to 90% similarity with other cereal alpha-amylases. A comparison of eleven cereal alpha-amylases also revealed three new conserved regions (I', II', and IV') not previously identified in the animal, bacterial, and fungal alpha-amylases. Regions I' and IV' are sites for intron splicing while region II' is probably involved in calcium binding. One of the rice alpha-amylase cDNAs, pOS103, encodes a protein that has two potential N-glycosylation sites, one in the signal peptide and the other in the mature portion of the protein. The cDNA clone, pOS137, encodes an alpha-amylase with a single glycosylation site in the signal peptide, suggesting that the mature OS137 isozyme is not glycosylated. Analysis of the expression of these genes in germinating rice seeds indicated that mRNA corresponding to pOS103 and pOS137 could be detected throughout a 48 h period of seed imbibition. RNA levels, however, were dramatically stimulated by treatment of embryoless half-seeds with exogenous GA3. Our results demonstrate that at least two forms of alpha-amylase are expressed in germinating rice seeds and that the expression of these genes is regulated by the phytohormone GA3.

Amino Acid Sequence↗
PubMed1990

[Oxygen free radical generation in ischemic-reperfused myocardium of rat in vivo].

Many studies have provided indirect evidence that there is a relationship between oxygen free radical and myocardial ischemic-reperfusion injury. In this study, we applied ESR spectroscopy to measure oxygen free radical generation in the acutely ischemic-reperfused heart of rat in vivo. The experimental model was established by 45 min ligation of the left anterior descending coronary artery (LAD) and 10 min reperfusion in vivo. The myocardial samples taken for ESR measurement were fresh-freezing tissue pieces. Meanwhile, the tissue ultrastructure was observed. We also observed the protective effect of superoxide dismutase (SOD) on myocardial ischemic-reperfusion injury. The results showed: 1. Large amounts of oxygen free radical were generated in the course of postischemic reperfusion. The amount of oxygen free radical produced in this process was positively related to the extent of myocardial damage. Oxygen free radical was at least one of the major cause of rat myocardial reperfusion injury observed in this experiment. 2. SOD could scavenge oxygen free radical and prevent or reduce reperfusion injury of rat heart in vivo.

Animals↗
PubMed1989

Extracellular ATP is a mitogen for 3T3, 3T6, and A431 cells and acts synergistically with other growth factors.

Extracellular ATP in concentrations of 5-50 microM displayed very little mitogenic activity by itself but it caused synergistic stimulation of [3H]thymidine incorporation in the presence of phorbol 12-tetradecanoate 13-acetate, epidermal growth factor, platelet-derived growth factor, insulin, adenosine, or 5'-(N-ethyl)carboxamidoadenosine. Cultures of Swiss 3T3, Swiss 3T6, A431, DDT1-MF2, and HFF cells were used. The percent of cell nuclei labeled with [3H]thymidine and cell number were also increased. ADP was equally mitogenic, while UTP and ITP were much less active. The effect of ATP was not due to hydrolysis by ectoenzymes to form adenosine, a known growth factor. Thus, the nonhydrolyzable analogue adenosine 5'-[beta, gamma-imido]triphosphate was mitogenic. In addition, it was found that ATP showed synergism in 3T6 and 3T3 cells when present for only the first hour of an incorporation assay, during which time no significant hydrolysis occurred. Furthermore, prolonged preincubation of cells with ATP reduced the mitogenic response to ATP but not to adenosine; preincubation with adenosine or N6-(R-phenylisopropyl)adenosine had the reverse effect. Finally, the effect of adenosine, but not of ATP, was inhibited by aminophylline. We conclude that extracellular ATP is a mitogen that interacts with P2 purinoceptors on the plasma membrane.

Adenosine↗