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Biomedical subjects

L Lu

Publications and source records attributed to L Lu.

At least 541 records · Page 30Linked to original sources
PubMed1989

Cl- channels in CF: lack of activation by protein kinase C and cAMP-dependent protein kinase.

Secretory chloride channels can be activated by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase in normal airway epithelial cells but not in cells from individuals with cystic fibrosis (CF). In excised, inside-out patches of apical membrane of normal human airway cells and airway cells from three patients with CF, the chloride channels exhibited a characteristic outwardly rectifying current-voltage relation and depolarization-induced activation. Channels from normal tissues were activated by both cAMP-dependent protein kinase and protein kinase C. However, chloride channels from CF patients could not be activated by either kinase. Thus, gating of normal epithelial chloride channels is regulated by both cAMP-dependent protein kinase and protein kinase C, and regulation by both kinases is defective in CF.

Adult↗
PubMed1989

The immunotherapeutic effects in tumor-bearing mice of Ly-6 monoclonal antibodies.

In vivo administration of Ly-6 mAb which recognize lymphoid differentiation Ag encoded for by the Ly-6 gene complex were found to have significant beneficial immunotherapeutic effects in tumor-bearing mice. The effectiveness of the mAb treatment in mice bearing sarcomas, leukemias, or melanomas was dependent on the host and not the tumor Ly-6 phenotype. The treatment was effective in nu/nu mice, although a more pronounced inhibition of tumor growth occurred in immunocompetent mice. The effectiveness of the therapy in immunocompetent mice was dependent on the dose of mAb and was influenced by the immunogenicity of the tumor. It ranged from significant growth inhibition of weakly immunogenic tumors to complete rejection of strongly immunogenic tumors. The results of cell-mediated cytotoxic assays of splenocytes from mAb-treated mice indicated that Ly-6 mAb treatment induced and/or augmented tumor-specific CTL as well as NK cell activity in these mice. Ly-6 mAb treatment represents a novel method for tumor immunotherapy using mAb recognizing lymphoid differentiation Ag with functional activities.

Adjuvants, Immunologic↗
PubMed1989

Gene transfer by lipofection in rabbit and human secretory epithelial cells.

Lipofection, a recently-developed method for gene transfer, was tested in secretory epithelial cells. Lipofection facilitated both transient DNA transfection with plasmids containing the chloramphenicol acetyltransferase gene and stable transfection with a plasmid containing the neomycin resistance gene, which confers resistance to the antibiotic G418 (Geneticin). Gene transfer occurred efficiently in a rabbit kidney medullary thick ascending limb cell line and in primary cultures of rabbit tracheal epithelial cells. The method was also effective in Simian virus 40-transformed human airway cells isolated from a normal individual and from a patient with cystic fibrosis (CF). Cytotoxicity was minimal, particularly when the time of exposure to the lipofectin-DNA was limited to 3-5 h (less than 5% cell loss). Thus, the lipofection method is useful for gene transfer in a variety of secretory epithelial cells and should be ideal for studies of defective secretory epithelial cell function in CF.

Animals↗
PubMed1989

Low dose total body irradiation: a potent anti-retroviral agent in vivo.

Immunosuppression characterizes many human diseases including leukemia and AIDS. Friend virus (FV)-induced murine leukemia is a useful model for studying both malignancy and immunosuppression. In a previous series of experiments, we have demonstrated that untreated FV-infected mice died within 40 days post-infection, whereas infected mice given 150 cGy total body irradiation (TBI) on days 5 and 12 exhibited long-term survival. In this report, we show that no leukemic cells or type C virus particles are found in the spleens of mice treated with TBI. In addition, both NK activity as well as bone marrow cell's proliferative responses to PHA and Con A were fully restored. This treatment produces long term control of FV-induced murine leukemia, and thus might have relevance for the treatment of a number of immunosuppressive diseases including AIDS.

Animals↗
PubMed1989

Construction of a recombinant human parvovirus B19: adeno-associated virus 2 (AAV) DNA inverted terminal repeats are functional in an AAV-B19 hybrid virus.

To facilitate genetic analysis of the human pathogenic parvovirus B19, we constructed a hybrid B19 viral genome in which the defective B19 inverted terminal repeats were replaced with the full-length inverted terminal repeats from a nonpathogenic human parvovirus, the adeno-associated virus 2 (AAV). The hybrid AAV-B19 genome was rescued from a recombinant plasmid and then the DNA was replicated upon transfection into adenovirus 2-infected human KB cells in the presence of AAV genes coding for proteins required for AAV DNA replication (AAV-Rep proteins). In addition, in the presence of AAV genes coding for the viral capsid proteins (AAV-Cap proteins), the rescued/replicated hybrid AAV-B19 genomes were packed into mature AAV progeny virions, which were subsequently released into culture supernatants. The recombinant AAV-B19 progeny virions were infectious for normal human bone marrow cells and strongly suppressed erythropoiesis in vitro. The availability of an infectious recombinant B19 virus should facilitate the mutational analysis of the viral genome, which, in turn, may yield information on individual viral gene functions in B19-induced pathogenesis. The hybrid AAV-B19 genome may also prove to be a useful vector for gene transfer in human bone marrow cells.

Blotting, Southern↗
PubMed1989

A cholecystokinin releasing peptide mediates feedback regulation of pancreatic secretion.

Diversion of bile pancreatic juice from the duodenum in rats stimulates cholecystokinin (CCK) release and pancreatic enzyme secretion. Intraduodenal perfusion of trypsin inhibits the release of CCK and pancreatic enzyme secretion. We hypothesized that the increased pancreatic enzyme secretion after pancreatic juice diversion is mediated by a trypsin-sensitive peptide secreted by the small intestine that stimulates release of CCK. To test this hypothesis, rats were surgically prepared with bile-pancreatic cannula and intestinal fistulas. Diversion of bile-pancreatic juice stimulated amylase output fivefold above basal and increased plasma CCK from a basal of 0.5 +/- 0.05 pM to 14 +/- 5 pM. Rapid perfusion (3 ml/min) of the duodenum with phosphate-buffered saline reversed the increase in amylase output and lowered the plasma CCK to 1.2 +/- 0.2. Administration of intestinal perfusate (3 ml/min) collected from a donor rat into the duodenum of a recipient rat with diversion of bile pancreatic juice increased amylase output threefold above basal and increased plasma CCK. The stimulatory activity of the intestinal perfusate was inactivated by treatment with trypsin but not by amylase or lipase. In addition, boiling did not alter the stimulatory activity of the intestinal perfusate. Perfusion of intestinal perfusate from donor rats pretreated with atropine did not stimulate amylase output and CCK release in recipient rats. By use of molecular membrane exclusion filters, stimulatory activity was retained (between 1,000 and 5,000). These results indicate that feedback regulation of pancreatic enzyme secretion is mediated by a CCK releasing peptide whose secretion from the duodenum is cholinergically mediated. This peptide is trypsin sensitive and has a molecular weight between 1,000 and 5,000.

Amylases↗
PubMed1989

Suppressive biological activity of a synthetic pentapeptide on highly enriched human and murine marrow hematopoietic progenitors: synergism with recombinant human tumor necrosis factor-alpha and interferon-gamma.

The synthetic pentapeptide pGlu-Glu-Asp-Cys-Lys (SPI) was evaluated in vitro alone and in combination with recombinant human tumor necrosis factor-alpha (TNF-alpha) and/or interferon-gamma (IFN-gamma) for effects on colony formation by hematopoietic progenitor cells (HPC) present in low-density (LD), nonadherent low-density T-lymphocyte-depleted (NALT-), and highly enriched sorted progenitor cells from normal human bone marrow. Progenitor cells in NALT- fractions were further enriched by cell sorting using two-color fluorescence on a Coulter Epics 753 flow cytometry apparatus with My10 and HLA-DR monoclonal antibodies. The sorted My10 DR+ progenitor cell population had a cloning efficiency of up to 38% for granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), and multipotential colony-forming units (CFU-GEMM). SP1 inhibited, by up to 86%, each of the colony-forming cells in a dose-dependent fashion. The sensitivities of the different progenitor cells to inhibition by the pentapeptide were the same when My10 DR+ marrow cells were used, and the progenitor cells in the My10 DR+ fraction were more sensitive than the cells in the LD or NALT- fraction to inhibition by SP1. The suppressive activity of SP1 on purified HPC was confirmed when 10(-3) M SP1 completely inhibited colony and cluster formation from a population of mouse bone marrow cells in which one of two cells was a CFU-GM. The effects of SP1 were not absolutely cell-cycle-specific for human HPC, but the non-S-phase cells were less sensitive than the S-phase cells to the suppressive effects of SP1. SP1 synergized with TNF-alpha and/or IFN-gamma to inhibit proliferation of progenitor cells using both LD or My10 DR+ human marrow cells stimulated by recombinant human interleukin 3 (IL-3). These studies suggest that the suppressive effect of SP1 occurs in the absence of certain accessory cells (e.g., monocytes and T-lymphocytes), that this effect may be mediated directly at the level of the HPC, and that this pentapeptide can be considered a candidate modulatory molecule for HPC proliferation.

Animals↗
PubMed1989

[Early ocular hypertension after cataract extraction].

The intraocular pressure (IOP) course during the first postoperative month was measured with Goldmann applanation tonometry in 93 eyes. The patients include 30 eyes of intracapsular cataract extraction (ICCE), 32 eyes of extracapsular cataract extraction (ECCE) and 31 eyes of ECCE combined with posterior chamber intraocular lens (PC-IOL) implantation. The preoperative average IOP was 13.30 +/- 3.24 mmHg in 93 eyes. The first day after cataract extraction was 25.33 +/- 8.18 mmHg and 59 eyes (63.44%) had an IOP higher than 23 mmHg. On the second day it was 16.03 +/- 7.54 mmHg. On the third day it was 14.69 +/- 5.45 mmHg. On the seventh day it was 13.32 +/- 3.44 mmHg and only 2 eyes (2.14%) IOP was higher than 23 mmHg. The first postoperative month average IOP was 12.93 +/- 1.31 mmHg and it was above 23 mmHg in only one eye. When compared with preoperation a significant increase in IOP was found postoperatively. But on the seventh day and after the first month there was no significant difference (P greater than 0.05). The IOP rise among ICCE group, ECCE group and PC-IOL group did not differ significantly.

Adult↗
PubMed1989

[Role of rostral ventrolateral medulla in the pressor response to intracerebroventricular injection of neostigmine].

Experiments were carried out on 47 urethane-chloralose anesthetized and flaxedil immobilized rabbits under artificial respiration. Intracerebroventricular injection (ICV) of neostigmine (100 micrograms/200 microliters) caused a marked increase in blood pressure (BP), left ventricular pressure (LVP) and renal sympathetic nerve discharge (RND), while femoral blood flow (FBF) and conductance (COND), were decreased and the heart rate (HR) was initially reduced and then slightly increased. Microinjection of atropine (0.25 micrograms/site) into the rostral ventrolateral medulla (rVLM) caused a decrease in BP, HR, RND and LVP and a increase in FBF and COND. Pretreatment of atropine injection into rVLM before ICV of neostigmine blocked the pressor response of neostigmine. These results indicate that rVLM is important for the pressor response to ICV neostigmine, which may be mediated via cholinergic muscarinic receptors in rVLM.

Animals↗
PubMed1988

Synergistic effects of purified recombinant human and murine B cell growth factor-1/IL-4 on colony formation in vitro by hematopoietic progenitor cells. Multiple actions.

Purified recombinant human B cell growth factor-1/IL-4 was evaluated, alone and in combination, with purified preparations of recombinant human (rhu) CSF or erythropoietin (Epo) for effects on colony formation by human bone marrow CFU-GM progenitor cells (GM) and burst forming unit-E progenitor cells. rhu IL-4 synergized with rhu G-CSF to enhance granulocyte colony formation, but had no effect on CFU-GM colony formation stimulated by rhu GM-CSF, rhu IL-3, or rhu CSF-1. Rhu IL-4 synergized with Epo to enhance BFU-E colony formation equal to that of Epo plus either rhu IL-3, rhu GM-CSF, or rhu G-CSF. Removal of adherent cells and T lymphocytes did not influence the synergistic activities of rhu IL-4. Rmu IL-4, synergized with rhu G-CSF, but not with rmu GM-CSF, rmu IL-3, or natural mu CSF-1, to enhance CFU-GM (mainly granulocyte) colony numbers by a greater than 90% pure preparation of murine CFU-GM. Also, rhu IL-4 at low concentrations enhanced release of CSF and at higher concentrations the release also of suppressor molecules from human monocytes and PHA-stimulated human T lymphocytes. Use of specific CSF antibodies suggested that rhu IL-4 was enhancing the release of G-CSF and CSF-1 from monocytes and the release of GM-CSF and possibly G-CSF from PHA-stimulated T lymphocytes. Use of antibodies for TNF-alpha, IFN-gamma, or TNF-beta as well as measurement of TNF and IFN titers suggested that the suppressor molecule(s) released from monocytes were acting with TNF-alpha and those released from PHA-stimulated T lymphocytes were acting with IFN-gamma. These results implicate B cell growth factor-1/IL-4 as a synergistic activity for hematopoietic progenitors and suggest that the actions can be on both progenitor and accessory cells.

Animals↗
PubMed1988

Effect of whole-body hyperthermia and cyclophosphamide on natural killer cell activity in murine erythroleukemia.

Mice infected with the polycythemia-inducing strain of Friend virus complex (FVC-P) develop a fatal erythroid disease similar in some respects to leukemia. Six- to eight-week-old DBA/2 female mice were injected i.v. with 0.5 ml of a virus suspension containing approximately 5 X 10(4) plaque-forming units and 5 X 10(3) spleen focus-forming units. Four treatment regimens were begun 3 days postinjection: (a) no treatment; (b) whole-body hyperthermia (WBH) alone; (c) cyclophosphamide (CY) alone; (d) WBH combined with CY. WBH treatment utilized a microwave generator operating at 2450 MHz. The i.p. temperature of the mice receiving WBH was maintained at 39.5-40 degrees C for 30 min. The CY was given i.p. at a dosage of 20 mg/kg of body weight. The various treatments, CY, WBH, CY + WBH were given once a week for 2 weeks. Natural killer cell activity was examined in all four groups of mice and was found to be significantly higher in the animals treated with WBH or CY. Our results show that WBH, either alone or in combination with CY, can prolong the lifespan of mice infected with lethal dosages of the FVC-P, possibly via a mechanism involving natural killer cells.

Animals↗
PubMed1988

Enhancement of release of granulocyte- and granulocyte-macrophage colony-stimulating factors from phytohemagglutinin-stimulated sorted subsets of human T lymphocytes by recombinant human tumor necrosis factor-alpha. Synergism with recombinant human IFN-gamma.

The influence of purified recombinant human TNF-alpha (rhuTNF-alpha) was assessed, alone and in combination with purified recombinant human IFN-gamma (rhuIFN-gamma), for its effects on enhancing release from human T lymphocytes of activities that stimulate colony formation by granulocyte-macrophage, erythroid, and multipotential progenitor cells. rhuTNF-alpha or rhuIFN-gamma enhanced the release of CSF, which were determined to be granulocyte-CSF and granulocyte-macrophage-CSF by human bone marrow colony assays, morphologic assessment of colony types, and neutralization studies with rabbit anti-human granulocyte-CSF and monoclonal mouse anti-human granulocyte-macrophage-CSF. The CSF were released only when PHA was used, whether or not rhuTNF-alpha and/or rhuIFN-gamma were present while the lymphocytes conditioned the medium. T lymphocytes were sorted into subsets by using three-color immunofluorescence and a dye laser flow cytometry system with cells incubated with biotin anti-Leu-4 labeled with Texas Red, FITC-conjugated anti-Leu-3a, and phycoerythrin-conjugated anti-Leu-2a. Both the Leu-4+3a+2a- and the Leu-4+2a+3a- cells released CSF in response to PHA, but the release of CSF from PHA-stimulated lymphocytes was enhanced by rhuTNF-alpha and rhuIFN-gamma only from the Leu-4+3a+2a- subset of cells. Use of the three-color cell sorting made it highly unlikely that NK cells were involved, because both sorted subsets were positive for Leu-4. rhuTNF-alpha and rhuIFN-gamma synergized to enhance release of CSF such that low concentrations of each molecule, which were inactive when used alone, were active when the two molecules were used together. These studies suggest a role, at least in vitro, for TNF-alpha and IFN-gamma in the release of CSF from subsets of T lymphocytes stimulated with PHA.

Adjuvants, Immunologic↗
PubMed1988

Curative effect of split low dosage total-body irradiation on mice infected with the polycythemia-inducing strain of the Friend virus complex.

Split low dose total-body irradiation (TBI) with 150 cGy was assessed for its efficacy in modifying the disease induced in DBA/2 mice by the polycythemia-inducing strain of the Friend virus complex (FVC-P, composed of a Friend murine leukemia helper virus and a spleen focus-forming virus). All FVC-P injected mice were dead within 40 days; however, infected mice receiving TBI on days 5 and 12 exhibited long-term survival. FVC-P-injected mice receiving TBI treatment on days 5 and 12 had normal leukocyte counts, normal spleen weights, and no detectable spleen focus-forming virus. Although the FVC-P-infected mice had decreased proportions of L3T4+ cells and increased proportions of Lyt-2+ cells, these were returned to normal following TBI treatment. Apparently the time sequence of TBI treatments is important since one treatment with TBI on day 5, or two treatments with TBI on days 12 and 18, was not as efficacious. The inability of in vitro irradiation doses of up to 1000 cGy to inactivate FVC-P which was subsequently injected into murine hosts suggests that the effectiveness of the TBI treatment in vivo is not due to a direct radiation effect on the virus. These results indicate a possible relationship between L3T4+ and Lyt-2+ numbers or their ratio in the curative efficacy of TBI in FVC-P-infected mice.

Animals↗
PubMed1988

Influence of T lymphocytes on hematopoiesis in a patient with T cell hypoplasia.

In this communication, we describe an unusual patient with a reported lifelong history of anemia. Investigation of the pathogenesis of this patient's bone marrow failure provided an interesting opportunity to determine the role of T cells in the regulation of human blood cell production. Phenotyping of the patient's mononuclear cells revealed severe T cell hypoplasia in both the peripheral blood and bone marrow. The patient's bone marrow was capable of producing 50-60% of the normal numbers of burst-forming units--erythroid (BFU-E) in the presence of optimal concentrations of erythropoietin, suggesting that marrow BFU-E formation is in part independent of T cells. Addition of small numbers of class I identical donor T cells enhanced BFU-E cloning efficiency to a level observed in normal controls. This enhancing effect was supplied by a T4+ (CD4) population of donor cells. The addition of donor T cells partially corrected the inability of patient marrow cells to produce megakaryocyte and mixed colonies. These studies suggest that prolonged T cell hypoplasia might deprive marrow progenitor and stem cells of a necessary enhancing effect that is required for sustained normal hematopoiesis. Such a T cell defect in rare instances may result in bone marrow failure.

Aged↗
PubMed1988

Detection of a human hematopoietic progenitor cell capable of forming blast cell containing colonies in vitro.

A progenitor cell CFU-B1 (blast cell colony forming unit) present in human bone marrow and capable of producing blast cell containing colonies in vitro was detected using a serum containing semisolid culture system. The CFU-B1 has the capacity not only to undergo self-renewal, but also commitment to a number of hematopoietic lineages. This progenitor cell therefore has characteristics which suggest that it is identical to or closely related to the human pluripotent hematopoietic stem cell. Pretreatment of marrow cells with 5 fluorouracil facilitated detection of CFU-B1 derived colonies. The formation of CFU-B1 derived colonies was dependent upon the addition of media conditioned by the human bladder carcinoma cell line 5637. The ability of 5637 CM (conditioned media) to support blast cell colony formation was in part but not totally ablated by pretreatment of the CM with an IL-1 alpha (interleukin-1) neutralizing antibody. This data suggests that IL-1 alpha plays a role in the regulation of primitive events occurring during human hematopoiesis. IL-1 alpha might be exerting these effects by either acting directly on the CFU-B1, causing marrow accessory cells to elaborate other cytokines or by synergizing with cytokines already present in 5637 CM.

Bone Marrow Cells↗