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Biomedical subjects

Z H Lin

Publications and source records attributed to Z H Lin.

At least 37 records · Page 2Linked to original sources
PubMed1991

Synergistic effect of human lactoferrin and recombinant murine interferon-gamma on disease progression in mice infected with the polycythemia-inducing strain of the Friend virus complex.

Mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC-P) have been used as a leukemic mouse model. In the present study, purified iron-saturated human lactoferrin (LF) and recombinant murine (rmu) interferon-gamma (IFN-gamma), alone or in combination, were used to influence disease progression in virally infected mice. DBA/2 mice were injected i.v. with FVC-P, and were treated s.c. with 100 micrograms LF at day 7, and/or rmuIFN-gamma at 5 x 10(4) units/day for 3 days beginning at day 6 after viral infection. Mice were assessed for survival, and also 14 days after virus inoculation, the mice were killed and spleen extracts were assessed for spleen focus forming virus (SFFV) titers by spleen focus forming unit (SFFU) assay, SFFV mRNA and genomic DNA expression, and natural killer (NK) cell activity. Treatment with LF or rmuIFN-gamma alone had little or no effect on SFFU numbers or SFFV mRNA or genomic DNA expression. However, dramatically decreased SFFV titers and levels of SFFV mRNA and genomic DNA were observed in mice treated with the combination of LF and rmuIFN-gamma. NK cell activity decreased by FVC-P was returned to normal levels by LF and rmuIFN-gamma. The combined treatment also enhanced the survival rates of FVC-P-infected mice. The results suggest synergistic suppressive effects of LF with rmuIFN-gamma on disease progression in FVC-P-infected mice. This information might be of significance as a potential therapy for patients with leukemia and those infected with retroviruses.

Animals↗
PubMed1991

Efficacy of recombinant human macrophage colony-stimulating factor in combination with whole-body hyperthermia in the treatment of mice infected with the polycythemia-inducing strain of the Friend virus complex.

Macrophage colony-stimulating factor (M-CSF, CSF-1) and whole-body hyperthermia (WBH) were evaluated, alone or in combination, for their capability to influence disease progression in mice inoculated with the polycythemia-inducing strain of the Friend virus complex (FVC-P). DBA/2 mice were injected i.v. with FVC-P and were treated with 20 micrograms/dose M-CSF s.c. twice a day for 5 days beginning 6 days after injection of FVC-P and/or with WBH (between 38.8 degrees C and 40.2 degrees C) given on days 5 and 12 after FVC-P injection. Fourteen days after viral inoculation, mice were sacrificed and spleen cells evaluated for: 1) spleen focus-forming virus (SFFV), by the spleen focus-forming unit assay (SFFU); 2) SFFV mRNA and genomic DNA using, respectively, Northern and Southern analysis with a B-E-SFFV DNA probe; and 3) natural killer (NK) cell activity, by 51Cr-release assay. Treatment with M-CSF or WBH alone had a small effect on SFFU numbers but little or no effect on SFFV mRNA expression and SFFV-specific DNA. However, dramatically decreased levels of SFFU and SFFV mRNA and specific DNA fragments were observed in mice treated with M-CSF in combination with WBH, and NK cell activity was restored to normal. These results suggest the possibility that M-CSF may have a therapeutic effect in combination with WBH in the in vivo treatment of certain hematologic malignancies and/or retroviral infections.

Animals↗
PubMed1990

Influence of interleukins 3,5, and 6 on the growth of eosinophil progenitors in highly enriched human bone marrow in the absence of serum.

Purified preparations of natural murine interleukin (IL)-5 and recombinant human IL-1 alpha, IL-3, and IL-6 were evaluated alone, and in combination, for effects in vitro on colony formation by eosinophil progenitors (eosinophil colony-forming units, CFU-Eos) in either nonadherent low-density T-lymphocyte depleted (NALT-) or fluorescence-activated cell sorted NALT-HLA-DR+ CD34 (My10) cells from normal human bone marrow, in the absence and presence of serum. Interleukins were assessed on CFU-Eos plated directly in agar, or on CFU-Eos placed in suspension culture for 7 days prior to plating in agar in the presence of IL-5. Eosinophil colonies were identified in situ by staining with Luxol fast blue. IL-3 and IL-5 acted in agar culture as direct stimulators of CFU-Eos, using highly purified cells in the HLA-DR+ My10 fraction of cells, the specificity for CFU-Eos being greatest for IL-5 and most demonstrable in the absence of serum. The IL-3 and IL-5 direct stimulating effects on CFU-Eos were additive. IL-1 alpha and IL-6 had little or no effect, alone or in combination with IL-3 and IL-5; however, IL-3, IL-5, and IL-6 each enhanced the number of IL-5-responsive CFU-Eos found after suspension culture compared to control medium, with the individual effects being additive when the molecules were combined. These results demonstrate that both IL-3 and IL-5, alone and in combination have direct-acting effects on CFU-Eos, with the greatest specificity for stimulation of pure Eos colonies and clusters residing in IL-5, and that IL-3, IL-5, and IL-6, alone and in combination, may play a role in the survival of CFU-Eos.

Antigens, CD↗
PubMed1990

Specificity of acidic phospholipids (CL & PA) in the activation of mitochondrial F0F1 ATPase by Mg2+.

The interaction of Mg2+ with native F0F1 ATPase was studied. The hydrolytic activity of F0F1 ATPase could be competitively activated by Mg2+, but the preincubation of F0F1 ATPase with cholate eliminated the Mg2+ effect. The result from the comparison of the effect of Mg2+ on F0F1 ATPase with that on soluble F1 ATPase, and the fact that the activation of Mg2+ on cholate-treated F0F1 ATPase could be reconstituted only by divalent acidic phospholipid cardiolipin, indicate that there exists a specificity between the acidic phospholipids of the mitochondrial inner membrane and Mg2+ enhancement of ATP-hydrolyzing activity of F0F1 ATPase.

Adenosine Triphosphate↗
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

[Clinical application of a paraumbilical axial flap--report of 16 cases].

The paraumbilical skin flap is based on the deep inferior epigastric artery and its paraumbilical perofrators. It can be transferred not only as a free flap but also as a pedicle flap or island flap. Since December 1987, we have successfully used the flap to repair the wounds and to reconstruct penis in 16 cases. The merits of the flap are as follows: The position of deep inferior epigastric artery is constant. The blood supply to the flap is good. The flap has a long vascular pedicle and the donor site is concealed.

Adult↗
PubMed1989

The effect of Mg2+ on mitochondrial F0.F1 ATPase and characteristics of the nucleotide binding sites.

The interaction of Mg2+ with nucleotide-washed F0.F1 ATPase from pig heart was studied. Mg2+ had no effect on nucleotide-washed F0.F1 ATPase, but it competitively inhibited the hydrolytic activity of washed F0.F1 ATPase preincubated with ADP and slightly activated the hydrolytic activity of washed F0.F1 ATPase preincubated with ATP. In the last two cases, it revealed negative cooperativity. The effect of Mg2+ on F0.F1 ATPase is therefore closely related to the characteristics of the nucleotide binding sites on mitochondrial F0.F1 ATPase.

Adenosine Diphosphate↗
PubMed1988

Keshan disease--an endemic mitochondrial cardiomyopathy in China.

Keshan disease (KD) is a cardiomyopathy endemic in certain areas of China, characterized by severe deterioration and multiple focal necrosis. In the present paper we describe abnormalities of the structure and function of myocardial mitochondria from patients with subacute Keshan disease. Activities of succinate dehydrogenase, succinic oxidase, cytochrome c oxidase, H(+)-ATPase and its sensitivity to oligomycin and the response of membrane potential to energization by ATP were significantly decreased. However, the spectrum of reduced-minus-oxidized cytochromes in patients' mitochondria showed no obvious difference in the content of cytochrome c oxidase (aa3). There was also a marked decrease in lipid fluidity of affected mitochondria, and an abnormal amount of moderately electron dense amorphous inclusions. Electron-microscopic x-ray microanalysis and exposure to protein digestion reagent demonstrated that these inclusions are not Ca3(PO4)2, but are, probably, proteinaceous in nature. Affected mitochondria had markedly decreased selenium content. The defects in myocardial mitochondria from patients with chronic Keshan disease were less extensive than those in patients with subacute Keshan disease. We propose that Keshan disease be classified as a form of "mitochondrial cardiomyopathy".

Cardiomyopathies↗
PubMed1987

Effects of some alcohols on the conformation of mitochondrial H+-ATPase complex and F1-ATPase from pig heart.

The conformations of the H+-ATPase complex and F1-ATPase in low concentrations of methanol, ethanol, n-propanol, iso-propanol and t-butanol were studied by circular dichroism. For F1-ATPase, all but methanol first increased and then decreased the circular dichroism magnitude of helical bands as the alcohol concentration was increased. With ethanol, n-propanol, iso-propanol and t-butanol, the alpha-helix content reached a maximum at about 5% alcohol and began to decrease at 10%. The content of beta-sheet showed the opposite effect, reaching a minimum at 5% and increasing slightly at higher concentrations. None of the alcohols studied had a significant effect on the conformation of the H+-ATPase complex. This difference implies that the alcohols had a greater effect on free F1-ATPase than on the membrane-bound F1-ATPase. The hydrophobic protein F0 and the membrane lipids in the H+-ATPase complex may stabilize and protect F1 from the effects of the alcohols.

1-Propanol↗
PubMed1987

Amino acid substitutions in the epsilon-subunit of the F1F0-ATPase of Escherichia coli.

A mutant strain of Escherichia coli was isolated in which Gly-48 of the mature epsilon-subunit of the energy-transducing adenosine triphosphatase was replaced by Asp. This amino acid substitution caused inhibition of ATPase activity (about 70%), loss of ATP-dependent proton translocation and lowered oxidative phosphorylation, but did not affect proton translocation through the F0. Purified F1-ATPase from the mutant strain bound to stripped membranes with the same affinity as the normal F1-ATPase. Partial revertant strains were isolated in which Pro-47 of the epsilon-subunit was replaced by Ser or Thr. Pro-47 and Gly-48 are predicted to be residues 2 and 3 in a Type II beta-turn and the Gly-48 to Asp substitution is predicted to cause a change from a Type II to a Type I or III beta-turn. Space-filling models of the beta-turn (residues 46-49) in the normal, mutant and partial revertant epsilon-subunits indicate that the peptide oxygen between Pro-47 and Gly-48 is in a different position to the peptide oxygen between Pro-47 and Asp-48 and that the substitution of Pro-47 by either Ser or Thr restores an oxygen close to the original position. It is suggested that the peptide oxygen between Pro-47 and Gly-48 of the epsilon-subunit is involved either structurally in inter-subunit H-bonding or directly in proton movements through the F1-ATPase.

Alleles↗
PubMed1987

On the mechanism of the reconstitution of F1-depleted ATPase complex with purified F1: possible conformational effects.

The membrane sector (F0) of H+-ATPase was prepared by trypsin and urea treatment of F1-F0 and reconstituted with purified F1. The oligomycin sensitivity of the reconstituted F1-F0 complex obtained by treating F1 or F0 with Mg2+ before binding is much higher than that obtained without Mg2+ treatment. The greater change in the intrinsic fluorescence of the reconstituted F1-F0 complex obtained by Mg2+ treatment suggests that conformational changes may occur during the reconstitution. We deduce that Mg2+ binds to membrane lipids, thus decreasing membrane fluidity and changing the physical state of the lipids to provide a suitable microenvironment for conformational changes in F0. The data also suggest that the conformational change in the F0 portion of the F1-F0 complex can be transmitted to the F1 portion, the conformation of which is in turn altered, resulting in the formation of an F1-F0 complex with high oligomycin sensitivity. On the other hand, Mg2+ may act on F1 directly to induce a suitable conformational change which is then transmitted to F0, resulting in the formation of an H+-ATPase with greater sensitivity to oligomycin.

Animals↗
PubMed1986

A kinetic study on the hydrolytic activity of mitochondrial ATPase (F0-F1 complex) from pig heart.

A kinetic study of mitochondrial ATPase (F0-F1 complex) from pig heart reported in this paper shows that when it was incubated with free Mg2+ (0-2mM), the hydrolytic activity of the ATPase was competitively activated by the Mg2+ and revealed no cooperativity. In the case of incubation with free ATP the hydrolytic activity was competitively inhibited and revealed positive cooperativity. These results are quite different from those of free F1 as obtained by Gautheron and coworkers (1). This indicates that either Mg2+ or ATP produces different effects on F1 when it is in different states, i.e., free state and membrane bound state. This may be considered to mean that the conformation of F1 in membrane bound state, which is influenced by F0 and membrane lipids is different from that of F1 in free state, thus exhibiting different catalytic site cooperativity between subunits, which is the fundamental feature of the mechanism of the enzyme action.

Animals↗