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Biomedical subjects

Z Z Chen

Publications and source records attributed to Z Z Chen.

At least 19 recordsLinked to original sources
PubMed2001

Cationic lipids enhanced cellular uptake and activity of bcl-2 antisense oligodeoxynucleotide G3139 in HL-60 cells.

AIM: To explore the effect of cationic lipid 1,3-di-oleoyloxy-2-(6-carboxy-spermyl)-propylamid (DOSPER) on cellular uptake and activity of bcl-2 antisense oligodeoxynucleotide G3139 in HL-60 cells. METHODS: The cell-associated mean fluorescence intensity and the percentage of cells with positive staining for Bcl-2 were measured by flow cytometry. The subcellular distribution of fluorescein isothiocyanate (FITC)-labeled G3139 was observed by fluorescence microscope and the bcl-2 mRNA level was detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: (1) DOSPER increased cellular uptake of G3139 into HL-60 cells greatly. When DOSPER/G3139 (microg : microg) was 2 : 1, the uptake of G3139 reached top after treatment for 2 h and increased about 20 times compared with application of G3139 alone. In the presence of DOSPER, G3139 was localized in nucleus and cytosol with a bright spotted fluorescence staining. However, G3139 was localized in cytoplasm with faint fluorescence in the absence of DOSPER. (2) Cell-associated G3139 could be effluxed out of cells. After treated with G3139 in the presence of DOSPER for 4 h, the cell-associated G3139 could be fitted by C(t)=68.2e(-0.60) t+31.8e(-0.02) t (% of initial value), with a half-life of approximately 1.1 h. In the absence of DOSPER, the cell-associated G3139 could be fitted by C(t)=64.8e(-2.27) t+35.2e(-0.04) t, with a half-life of about 18 min. (3) In the presence of DOSPER, G3139 1.0 micromol/L specially reduced bcl-2 mRNA level, and Bcl-2 protein decreased from 97 % +/- 4 % to 70.6 % +/- 2.1 %. CONCLUSION: DOSPER enhanced the activity of G3139 and it might be attributed to increase of the cellular uptake and change of the subcellular distribution of G3139.

Biological Transport↗
PubMed1995

Hemoglobins of Kiefferulus, sister genus of Chironomus (Diptera: Insecta): evolution of the Hb VIIB cluster.

A genomic clone containing hemoglobin genes was isolated from a species of the chironomid genus Kiefferulus. Eight genes, including an apparent pseudogene, were sequenced and the amino acid sequences of the putative proteins were determined. By comparison to the previously described hemoglobins in the sister-genus Chironomus, they were identified as members of the dimeric Hb VIIB group. The results indicate that the existence of clusters of hemoglobin genes may be a common feature in chironomids and not just confined to Chironomus. The Kiefferulus genes show greatest similarity of amino acid sequence to Hb VIIB-7 from the Chironomus cluster. The results suggest that the ancestral cluster contained at least two gene types, one of which gave rise to VIIB-7 and the Kiefferulus genes while the other gave rise to the other Chironomus VIIB genes. Both clusters appear to have increased in size by duplication or unequal crossing over since the separation of the genera. It also appears that an unrelated gene present in the Chironomus cluster, Hb-Y, arose from a completely independent origin with no apparent equivalent gene anywhere in the genome of Kiefferulus or some other Chironomus species.

Amino Acid Sequence↗
PubMed1994

Genetic mechanism of leukemia predisposition in a family with 7 cases of acute myeloid leukemia.

This paper describes a family in which seven members, involving three consecutive generations, suffered from acute myeloid leukemia during the past 16 years. The genetic abnormalities were vertically transmitted in a Mendelian dominant manner without sex linkage. Cytogenetic approaches, such as G-banding karyotypes, micronuclei (MN), chromosome aberrations (CA), fragile sites (Fra), cell cycle time (Tc), sister chromatid exchanges (SCE), silver-staining nucleolar organizer regions (Ag-NOR), and silver-staining acrocentric chromosome satellite association (Ag-AA), were investigated on 19 presently healthy members of the family, compared with 10 normal controls. The results showed that their G-banding chromosome karyotypes were normal, without a single similarly located fragile site being found to be carried commonly by the blood relations, although the rare fragile site frequency in the blood relations group was higher than that in the non-blood relations group or normal controls. On the other hand, SCE and Ag-NOR were lowered in the blood relations. In III-13 and IV-3 of the pedigree, in particular, the prolonged cell cycle time with distinctly abnormal SCE and Ag-NOR might predict a high risk for leukemia. Hence the follow-up of this remarkable family is being continued.

Acute Disease↗
PubMed1994

[A clinical study on the tumor associated antigen CA50 in the monitoring of genitourinary malignancies].

The tumor associated antigen CA50 was examined in serum level of 84 patients with genitourinary malignancies, 48 patients with genitourinary benign diseases and 35 normal persons by immunoradiometric assay (IRMA). The mean CA50 value in the patients with genitourinary malignancy was much higher then that in patients with benign genitourinary diseases and that in the normal control group (P < 0.05-0.01). Taking 17 u/ml as the upper limit of normal range, the positive rates were 55% (11/20) of patients with renal cell carcinoma, 78% (7/8) in pyeloureteric carcinoma, 65% (30/46) in bladder cancer and 70% (7/10) in genital malignancies. The sensitivity of CA50 for the patients with genitourinary malignancy was 65.5% (55/84) and the specificity was 87.5% (42/48). The measurement of level of serum CA50 also could be used to monitor the clinical change and responses during the course of treatment. It might be helpful to predict the recurrence of tumor after surgical treatment.

Adult↗
PubMed1992

A cDNA clone with anti-oncogene activity.

A cDNA clone, p14-6, which has an anti-oncogene activity on the v-Ki-Ras oncogene-transformed malignant cell line DT, was found. This clone was recovered from the revertant R14 cells, which had been isolated by transfections of DT cells with a normal human fibroblast cDNA library cloned in pcD2, an Okayama-Berg vector. When transfected into DT cells, p14-6 clone gave rise to phenotypical flat reversion in 5-15% of DT transfectant colonies. The p14-6-transfected flat cell line, RR, was proven to be a true revertant with significantly reduced malignancy by in vitro and in vivo malignancy tests. All other clones recovered from R14 cells were unable to cause this reversion. Molecular hybridizations showed that the p14-6 was inserted into RR genome as tandem repeats, and no structural change was found in the v-Ki-Ras oncogene in RR genome. These facts suggest that the anti-oncogene activity of the p14-6 clone on the DT cells may be exerted through expression of the cDNA contained in this clone.

Animals↗
PubMed1991

Stromal populations and fibrosis in human long-term bone marrow cultures.

An immunofluorescence study of the adherent layer of human long-term bone marrow cultures (HLTBMC) revealed the following surface markers on the different stromal cell populations: stromal fibroblastic cells CD10+, FIB86.3+, CD13+, CD71+; adipocytes CD10+, FIB86.3-, CD13+, CD71-/+; and macrophages CD10-/+, FIB86.3+, CD13+, CD71-/+, CD14+, CD33+, CD25+, HLA-DR+, CD4+, CD19+, CD45+. The markers of the stromal fibroblastic cells in HLTBMC were similar to those of twice-passaged fibroblasts not only from bone marrow and spleen, but also from a hemopoietic non-supportive organ such as the skin. Some of the cultured human umbilical vein endothelial cells used as controls were found to be CD25+, demonstrating for the first time the interleukin-2 receptor p55 chain on normal non-hemopoietic cells. The stromal fibroblastic cells are overrepresented compared to the small non-macrophage hemopoietic cell population in the adherent layer of HLTBMC. In addition, silver staining revealed an increased reticulin content in most of the HLTBMC. An excessive growth of stromal fibroblastic cells and an excessive deposition of their product, the reticulin fibers, are the hallmark of myelofibrosis. The finding of equivalent observations in HLTBMC suggests that the hitherto unexplained, premature quenching of hemopoiesis in HLTBMC might at least partly be due to mechanisms similar to those operating in myelofibrosis in vivo.

Antigens, CD↗
PubMed1990

Morphological evidence for a motile behavior by plasma cells.

Immunofluorescence microscopy of the adherent layer of human long-term bone marrow cultures (HLTBMCs) consistently revealed motility-associated features in a part of the plasma cells. Not only were small surface blebs observed, but also long extensions whose morphology was reminiscent of neuronal axons. The observations were made in all HLTBMCs established with normal as well as myelomatous bone marrow (BM). Plasma cells with long extensions were also noticed on May-Grünwald-Giemsa smears of original uncultured BM from normal individuals and patients with myelomatous disorders. This suggests that the motility-associated morphological features occur in vivo as well as in vitro. The observations were most striking in the one case of plasma cell leukemia, both in culture as well as in the BM smear.

Bone Marrow Cells↗
PubMed1989

Antigen presentation abrogated in cells expressing truncated Ia molecules.

Oligonucleotide site-directed mutagenesis was used to introduce a premature stop codon in wildtype A beta k and A alpha k cDNA clones to create truncated A beta k and A alpha k molecules lacking the cytoplasmic domain. Transfected B lymphoma cells expressing an I-Ak molecule with a truncated beta-chain or with truncated alpha- and beta-chains showed profound defects in two Ia-related functions: Ia-restricted Ag presentation and intracytoplasmic signaling. The ability of these transfected cell lines to activate autoreactive T hybrids was markedly impaired whereas loss of Ag presentation to nominal Ag-specific T hybrids was more subtle. Ia-mediated transmembrane signaling as measured by PKC translocation from cytosol to nucleus after stimulation with anti-Ak antibody was greatly affected by truncation of the A beta and A alpha cytoplasmic domains. These results indicate an important role for the highly conserved cytoplasmic domain in Ia-mediated responses.

Amino Acid Sequence↗
PubMed1989

Altered I-A protein-mediated transmembrane signaling in B cells that express truncated I-Ak protein.

Recent evidence suggests that the major histocompatibility complex class II molecules of B lymphocytes function as signal-transducing receptors during the generation of T lymphocyte-dependent humoral immune responses. By analogy with other receptors, we postulate that perturbation of the class II molecules is coupled to the generation of intracellular second messengers through interactions involving the transmembrane and/or cytoplasmic domains of the class II molecules. We report a series of experiments that assess which amino acids of the class II molecule I-Ak are required for coupling it to the signal-transduction pathway. We prepared a series of B-lymphocyte transfectants that express I-Ak molecules with COOH-terminal truncations of either the Ak alpha or Ak beta chain or both. The ability of each transfected class II molecule to transduce a signal after being bound by monoclonal antibody was found by monitoring the translocation of protein kinase C from the cytosol to the "nuclear compartment" of the transfected B lymphocyte. Results indicate that the Ak beta chain plays the dominant role in signal transduction and that the 6 cytoplasmic amino acids of Ak beta chain most proximal to the inner plasma membrane are of greatest importance in coupling I-Ak molecules to the molecules of the signaling cascade.

Amino Acid Sequence↗
PubMed1989

A quantitative and dynamic study of endothelial cells and megakaryocytes in human long-term bone marrow cultures.

The quantitative evolution of endothelial cells (ECs) in Dexter-type human long-term bone marrow cultures (HLTBMCs) was investigated. Using monoclonal antibodies directed against von Willebrand factor (vWF) and against membrane antigens (EN-4 and PAL-E), a low percentage--usually less than 1% of stromal cells--of ECs was detected in all confluent cultures established from 11 different bone marrow samples. Generally these cells are not associated directly with the areas of myelopoiesis ("cobblestone areas"). ECs cannot be demonstrated in the adherent layer of most young, non-confluent, and of some old, HLTBMCs. In some instances, morphological features suggestive of dynamic behavior were seen (sprouting, canal formation). In addition, a very low proportion of vWF-positive megakaryocytic cells was found in 4 of 11 cultures, always in direct contact with the stromal fibroblastic cells.

Bone Marrow↗
PubMed1989

[Synthesis of CSD and it's antitumor effect].

Synthesis of a new polyamine inhibitor dicyclohexylamine sulfonyl chloride (CSD), the structural identification of the synthetic product, and the animal experimental results of it's antitumor effects are reported. Mice bearing leukemia P388 and Ehrlich ascites carcinoma treated with CSD at doses of 50-100 mg/kg p.o. could prolong the survival time of tumor bearing animals. CSD could significantly inhibit spermidine synthesis in vivo. The inhibition was positively correlated to it's antitumor effect, indicating that the antitumor mechanism of CSD is by blocking spermidine synthesis.

Animals↗
PubMed1989

The nature of the adherent hemopoietic cells in human long-term bone marrow cultures (HLTBMCs): presence of lymphocytes and plasma cells next to the myelomonocytic population.

An immunological analysis of the nonmacrophage hemopoietic cells in the adherent layer of human long-term bone marrow cultures was performed in situ. It revealed not only the expected granulocytic and monocytic cells, but an important lymphoid population as well. The latter consisted of cells bearing the markers of mature T lymphocytes, B lymphocytes, and plasma cells. These cells were also present in the hemopoietic foci of the adherent layer, the so-called cobblestone areas. Although more CD8+ than CD4+ lymphocytes were generally present in the initial bone marrow inoculum, both the adherent layer and the nonadherent fraction disclosed a preponderance of CD4+ cells after a short period of culture. The majority of the lymphoid cells were present in the adherent layer, rather than in the nonadherent fraction of the cultures. The long-term presence of lymphoid elements in the adherent layer suggests their affinity for the bone marrow stroma and the possible enhancement of their persistence in vitro by contact with these cells.

Antibodies, Monoclonal↗
PubMed1989

Human long-term bone marrow cultures (HLTBMCs) in myelomatous disorders.

Human long-term bone marrow cultures (HLTBMCs) were established with bone marrow (BM) collected from five patients with myelomatous disorders (four with multiple myeloma, one with plasma cell leukemia). In all cases, up to at least 6 weeks of culture, there was a persistence of the monoclonal plasma cell population in the adherent layer of the culture. In some cultures proliferating plasma cells could be demonstrated by the Ki-67 monoclonal antibody. In all instances a paraprotein could be shown in the conditioned medium. This study demonstrates that malignant plasma cells, in analogy to their normal counterparts, have an affinity for the BM stroma and suggests that their long-term survival might be enhanced by their interaction with it.

Bone Marrow↗
PubMed1989

Comparison of human long-term bone marrow cultures (HLTBMCs) established from fresh and post-cryopreservation bone marrow samples from living and cadaver donors.

Human long-term bone marrow cultures (HLTBMCs) were established from thawed post-cryopreservation, as well as from cadaver donor bone marrow (BM) samples. The longevity was similar in the different series of HLTBMCs examined. CFU-GM could be cultured out of cadaver donor BM. This indicates that previously healthy people, under the conditions generally accepted as suitable for organ donation, could become suitable donors for allogeneic BM transplantation.

Bone Marrow Cells↗
PubMed1988

Determinants of growth-promoting activity reside in the A-domain of insulin-like growth factor I.

A two-chain, disulfide linked, insulin-like compound embodying the A-domain of insulin-like growth factor I (IGF-I) and the B-chain of insulin has been synthesized and characterized with respect to insulin-like biological activity and growth-promoting potency. The compound displays a potency of ca. 41% relative to insulin in assays for insulin-like activity (e.g., lipogenesis) but significantly higher activity than insulin, ca. 730% relative to insulin, in growth factor assays (e.g., thymidine incorporation). The compound is, however, a less potent growth factor than IGF-I itself, ca. 26.5% relative to IGF-I, and is not recognized by IGF carrier proteins. We conclude that structural features contained in the A-domain of IGF-I are primarily responsible for the growth-promoting ability displayed by IGF-I, while features in the B-domain are responsible for recognition by IGF carrier proteins.

Amino Acid Sequence↗
PubMed1988

Ligand-induced desensitization of B-cell membrane immunoglobulin-mediated Ca2+ mobilization and protein kinase C translocation.

Binding of ligand to B-cell membrane immunoglobulin (mIg) can lead to activation of a number of distinct biologic responses, including altered expression of genes encoding c-fos, c-myc, and Ia, as well as proliferation and immunologic tolerance. Tolerance could reflect a functional uncoupling of receptors from systems that generate intracellular second messengers (i.e., receptor desensitization). To better understand the molecular basis of immune regulation, we examined the ability of mIg to function as a signal transducer after the cell's initial contact with mIg-binding ligand. The results show that ligand binding to as little as 2-10% of mIgM or mIgD renders the cell unresponsive to ligand binding to the reciprocal isotype as judged by Ca2+ mobilization and protein kinase C translocation responses. This heterologous receptor desensitization lasts longer than 24 hr and does not reflect loss of receptor from the cell surface. Studies with the calcium ionophore ionomycin, 1,2-dioctanoyl-sn-glycerol, and the protein kinase inhibitor staurosporine indicate that both protein kinase C-dependent and protein kinase C-independent (staurosporine-insensitive) mechanisms mediate heterologous desensitization after mIg crosslinking.

Animals↗