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Biomedical subjects

J L Zhang

Publications and source records attributed to J L Zhang.

At least 37 records · Page 2Linked to original sources
PubMed1999

Alterations of T-lymphocyte subsets, soluble IL-2 receptor, and IgE in peripheral blood of children with acute asthma attacks.

BACKGROUND: T-cell activation and alteration of cytokines are involved in the pathogenesis of atopic asthma. However, the profile of circulating T-lymphocyte subsets, related cytokines, and plasma IgE during acute asthma attacks is still unclear. OBJECTIVE: In an attempt to illustrate the dynamics of these parameters in asthma attacks, we investigated the changes of T-cell subsets, lymphocyte activation, soluble IL-2R, and IgE in peripheral blood in children during and after acute asthma attacks. METHODS: This study was carried out in a cohort of Chinese children (n = 59) with acute asthma attacks. Immunoassays were performed when the patients had acute attacks before treatment, and the patients were reexamined in the 4 weeks after the resolution of acute attacks with therapy. Paired t tests were used for the statistical analysis of these patients to compare the data obtained during and after the acute attacks. Twenty healthy, age-matched subjects were used as normal control subjects. Nine children with long-term stable asthma were used as control subjects with stable asthma. RESULTS: CD3+, CD4+, CD8+, and IL-2R+ (CD25+) cells; plasma soluble IL-2 receptor; and IgE were significantly higher in patients with acute attacks than in control subjects. (P <.05, P <.05, P <.001, P <.05, P <.0001, and P <.0001, respectively). Immunoelectron microscopy exhibited an increased expression of IL-2R on lymphocytes in acute attacks as compared to control subjects. The abnormalities returned to normal, with the exception of IgE, when clinical remission was achieved after treatment. Correlation analyses revealed a positive relationship between plasma IgE and soluble IL-2R in asthma attacks (r = 0.83, P =.0001). Plasma IgE and soluble IL-2R of those who were in remission positively correlated with their production in acute attacks (r = 0.58, P =.001 and r = 0.71, P =.0001, respectively). CONCLUSION: This study suggests that (1) the percentage of CD4+, CD8+, or IL-2R+ lymphocytes in peripheral blood was significantly elevated during acute attacks and returned to normal ranges after complete remission was achieved; (2) plasma soluble IL-2R is a sensitive marker for asthma activity; and (3) atopic asthmatic children seem to have a hereditary predisposition of having higher levels of soluble IL-2R in asthma attacks, coinherited with the trait of IgE.

Acute Disease↗
PubMed1999

[Effects of endogenous nitric oxide on pulmonary artery hypertension and lung injury induced by endotoxin].

Changes in mean artery pressure (MAP), pulmonary artery pressure (PAP) and nitric oxide (NO) contents in inflow and outflow pulmonary blood(IPB,OPB) were observed after endotoxin lipopolysacchride (LPS) was injected i.v. in rabbits. Changes of PAP and lung injury were also observed after inhibitor of NO synthesis L-NNA or inhibitor of inducible NO synthesis AG was pre-injected by vein. The results showed that MAP decreased significantly after LPS administration, and 0.5-2h later PAP showed some increase (P<0.05) being maximum at PAP (1h) during which the content of NO in IPB was detectably decreased but NO in OPB did not. NO contents in OPB at 3h and in IPB and OPB at 5h increased significantly following LPS administration as compared with control.PAP correlated negatively with NO in IPB at the time before and 1h after LPS injection, which did not exist at 3 and 5h after LPS injection. After L-NNA pretreatment, when PAP elevated significantly, the MDA content in IPB and OPB also showed significant increase, while animal survival rate fell significantly. Light microscopic examination showed severe alveolar atelectasis, significant congestion and sequestration of leukocytes in lung tissue. When pretreated with AG, MAP elevated significantly in 3-5h, PAP remained unchanged. The MDA content in blood was lower at 5h in the LPS injected group with less pathological changes in lung tissue at 5h compared with the LPS group. The above results suggested that there was pulmonary hypertension in the early stage after endotoxin administration. The decrease of NO content in IPB may be one of the mechanisms underlying pulmonary artery hypertension(PAH).NO seemed to alleviate PAH and lung injury at the early stage after endotoxin administration. When iNOS was induced at the later stage, NO contributed to lung injury caused by endotoxin.

Animals↗
PubMed1998

The bis-azo compound FP-21399 inhibits HIV-1 replication by preventing viral entry.

The bis-azo compound FP-21399 inhibits HIV-1 infection. We now show that FP-21399 acts on the HIV-1 envelope glycoprotein to prevent viral replication. This compound targets the entry step of the HIV-1 replication cycle as demonstrated by time-of-addition and single cycle viral entry assays. The entry of SIVmac239, which uses the same coreceptors (CD4/CCR5) as HIV-1, was not inhibited by FP-21399, indicating that the antiviral effect of FP-21399 is specific for the HIV-1 envelope glycoprotein and is not dependent upon the cellular receptors CD4 and CCR5. FP-21399 inhibits neither the activity of HIV-1 reverse transcriptase nor the expression of HIV-1 early mRNA. Finally, this compound inhibits gp120 shedding of the T-tropic virus. Our results suggest that the anti-HIV activity of FP-21399 is due to its interaction with HIV-1 gp120/41 complex during viral entry.

Animals↗
PubMed1998

Aberrant splicing of intron 1 leads to the heterogeneous 5' UTR and decreased expression of waxy gene in rice cultivars of intermediate amylose content.

We have previously reported that three distinct patterns of waxy (Wx) gene transcript accumulation were present in 31 rice cultivars. The cultivars with high amylose content (group I) contain a 2.3 kb mature Wx mRNA, cultivars with intermediate amylose content (group II) produce both a 3.3 kb Wx pre-mRNA, which contains intron 1, and the 2.3 kb Wx mature mRNA, and cultivars with no amylose (group III) accumulate only the 3.3 kb Wx pre-mRNA. Analyses of the cDNAs reveals that four splice donor sites and three splice acceptor sites in intron 1 give rise to six splicing patterns in 2.3 kb Wx mRNA of group II cultivars. In addition, aberrant intron 1 excision causes either deletion of 4 or 5 nucleotides, or addition of 7 and 13 nucleotides at the junction of exon 1 and exon 2 of the 2.3 kb mRNA. In contrast, only one normal splicing pattern (one splice donor site and one splice acceptor site) was found in the 2.3 kb mRNA of group I cultivars. Nucleotide sequences of the Wx intron 1 in group I and group II cultivars differ by 16 individual bases. We suggest that these deletions or additions contribute to inefficient splicing of intron 1 from the 3.3 kb Wx pre-mRNA, as well as an aberrant splicing of the Wx intron 1 to produce the 2.3 kb mRNA with a heterogeneous 5' untranslated region (5'-UTR). As a consequence, the total amount of translatable Wx mRNA, and therefore the Wx protein and amylose content, are reduced in the group II cultivars compared with the group I cultivars.

Alternative Splicing↗
PubMed1997

Modification of apolipoprotein(a) lysine binding site reduces atherosclerosis in transgenic mice.

Lipoprotein(a) contributes to the development of atherosclerosis through the binding of its plasminogen-like apolipoprotein(a) component to fibrin and other plasminogen substrates. Apolipoprotein(a) contains a major lysine binding site in one of its kringle domains. Destruction of this site by mutagenesis greatly reduces the binding of apolipoprotein(a) to lysine and fibrin. Transgenic mice expressing this mutant form of apolipoprotein(a) as well as mice expressing wild-type apolipoprotein(a) have been created in an inbred mouse strain. The wild-type apolipoprotein(a) transgenic mice have a fivefold increase in the development of lipid lesions, as well as a large increase in the focal deposition of apolipoprotein(a) in the aorta, compared with the lysine binding site mutant strain and to nontransgenic littermates. The results demonstrate the key role of this lysine binding site in the pathogenic activity of apolipoprotein(a) in a murine model system.

Animals↗
PubMed1997

Inhibitory effects of fluorescein isothiocyanate photoactivation on lymphatic pump activity.

The effects of photoactivation of fluorescein 5'-isothiocyanate (FITC)-dextran on lymphatic pump activity of rat mesenteric collecting vessel were studied in vivo. Rats were anesthetized with intraperitoneal alpha-chloralose and urethane, and the mesenteries were studied by using intravital videomicroscopic techniques. The diameter of the collecting lymph vessels were continuously monitored and lymphatic pump parameters (end diastolic diameter, end systolic diameter, stroke volume index, ejection fraction, contraction frequency, and pump flow index) were calculated. FITC-dextran (42 nmol/100 g body wt) without illumination caused no disturbance of lymphatic pump activity. Photoactivated FITC-dextran significantly increased end systolic diameter and decreased stroke volume index, ejection fraction, contraction frequency, and pump flow index. End diastolic diameter was not changed throughout the experiment. Superoxide dismutase (120 U/ml) and catalase (5000 U/ml) had no protective effect on photoactivated FITC-induced pump dysfunction, while histidine (singlet oxygen quencher, 10 mM) significantly prevented the disturbance of pump parameters. These results indicate that photoactivation of FITC induces negative chronotropic and negative inotropic effects in lymphatic pump activity through generation of singlet oxygen in the mesentery.

Animals↗
PubMed1997

Topotecan inhibits human immunodeficiency virus type 1 infection through a topoisomerase-independent mechanism in a cell line with altered topoisomerase I.

Topotecan (TPT), a known inhibitor of topoisomerase I, has previously been shown to inhibit the replication of several viruses. The mechanism of inhibition was proposed to be the inhibition of topoisomerase I. We report that TPT decreased replication of human immunodeficiency virus type 1 (HIV-1) in CPT-K5, a cell line with a topoisomerase I mutation. TPT inhibited production of HIV-1 RNA and p24 in CPT-K5 and wild-type cells equally effectively. The antiviral effects of TPT were observed not only in the topoisomerase-mutated CPT-K5 line but also in peripheral blood mononuclear cells (PBMC) acutely infected with clinical isolates and in OM10.1 cells latently infected with HIV and activated by tumor necrosis factor alpha. Little toxicity from TPT was noted in HIV-1-infected PBMC and in CPT-K5 and OM10.1 cells as measured by cell growth and proliferation assays. These observations suggest that TPT targets factors in virus replication other than cellular topoisomerase I and inhibits cytokine-mediated activation in latently infected cells by means other than cytotoxicity. These results suggest a potential for TPT and for other camptothecins in anti-HIV therapy alone and in combination with other antiretroviral drugs.

Camptothecin↗
PubMed1997

[Interactions between ciprofloxacin, Mg2+, Mn2+ and DNA by electrochemical method].

Interactions between ciprofloxacin (CPFX), Mg2+, Mn2+ and DNA, and their polarographic and voltammetric behaviour were studied. In 0.1 mol.L-1 NH3-NH4Cl buffer solution (pH 9.2), a new reduction peak was obtained by linear-sweep voltammetry with Ep = -1.72 V(vs Ag/AgCl) when adding DNA to CPFX solution, which implies binding of CPFX with DNA. In the presence of Mg2+ or Mn2+, another new sensitive reduction peak, whose peak potential is more negative (Ep = -1.78 V), was obtained which suggested that Mg2+ or Mn2+ took part in the interaction between CPFX and DNA resulting in a ternary complex of CPFX-Mg-DNA. The peak current (ip) is proportional to the concentration of DNA over the range of 1.18 x 10(-4)-3.33 x 10(-4) mol.L-1. In this paper, the properties of the peak current were studied in detail, the result showed that the electrode reaction was irreversible and the ip was influenced by adsorption. The electrode reaction mechanism was also probed into. The CPFX molecule in the complex was reduced on the electrode. Furthermore, CPFX-Mg was shown ot be intercalated between the stacked base pairs of native DNA.

Ciprofloxacin↗
PubMed1996

Reductase domain cysteines 1048 and 1114 are critical for catalytic activity of human endothelial cell nitric oxide synthase as probed by site-directed mutagenesis.

We examined whether highly conserved cysteine residues in the reductase domain of the constitutive isoform of nitric oxide synthase in human endothelial cells (ecNOS) are crucial for catalytic activity of the enzyme. Substitution of alanine for cysteines 976 (Cys-976), 991 (Cys-991), 1048 (Cys-1048), or 1114 (Cys-1114), located in the reductase domain of human ecNOS, was achieved by oligonucleotide-directed mutagenesis and expression in COS-7 cells. The specific activity of ecNOS was > 7-fold increased in wild-type and in mutants Cys-976 and Cys-991, but not in mutants Cys-1048 and Cys-1114. However, Western blot analysis indicated that expression of ecNOS protein was comparable in wild-type and in all mutants. NADPH concentration-dependent L-citrulline formation and NADPH oxidation during L-arginine metabolism were reduced in mutants Cys-1048 and Cys-1114 compared to wild-type. Similarly, NADPH cytochrome c reductase activity was increased in a time-dependent fashion in wild-type but not in mutants Cys-1048 and Cys-1114. These results indicate that Cys-1048 and Cys-1114 residues in the NADPH binding site of the reductase domain are critical for human ecNOS activity. The lack of utilization of NADPH in L-arginine metabolism and in cytochrome c reduction suggests that these active site cysteine residues may be responsible for binding of NADPH and/or for electron transfer in human ecNOS.

Animals↗
PubMed1996

[Cholecystokinin-octapeptide (CCK-8) reverses experimental endotoxin shock].

The effects of CCK-8 on the mean arterial pressure (MAP), blood components and path-morphological changes during endotoxin shock (endotoxin, 8 mg/kg b.w.iv.) in rats, as well as on the 24 h mortality rate (MR) of the lead-sensitized rats in endotoxin shock (endotoxin 1 microgram/100 g b.w.iv.) were observed. The results showed that injection of CCK in ES rats led to an increase in MAP, and a reduction of hematocrit and platelet as well as white cell count; the mortality rate decreased and the lesion in main organs lessened. It is suggested that release of endogenous CCK has important protective action during endotoxin shock.

Animals↗
PubMed1996

[HPLC determination of five constituents in plants of genus Ligusticum].

A RP-HPLC method was established to separate and determine five constituents in plants of genus Ligusticum by using an ODS column (Hypersil-C18, 5 microns) and acetonitrile (containing 1.25% CHCl3)--water (saturated with CHCl3) as mobile phase for gradient elution. The five constituents were ferulic acid, scopoletin, 3-butyl-phthalide, ligustilide, and diligustide. They were detected at 284 nm. Peak purity was monitored by photodiode array detector. Benzthiazide was used as the internal standard. The method is simple, fast, sensitive and reproducible.

4-Butyrolactone↗
PubMed1995

The apolipoprotein(a) gene is regulated by sex hormones and acute-phase inducers in YAC transgenic mice.

High plasma concentrations of apolipoprotein (a) (apo(a)) have been implicated as a major independent risk factor for atherosclerosis in humans. Apo(a) is a large, evolutionarily new gene (present primarily in primates) for which considerable controversy exists concerning the factors that regulate its expression. To investigate the in vivo regulation of apo(a), we have created several lines of YAC transgenic mice containing a 110-kb human apo(a) gene surrounded by greater than 60 kb of 5' and 3' flanking DNA. Studies in humans have suggested that acute-phase inducers increase and sex steroids decrease apo(a) concentrations, but these results are controversial. Analysis of the YAC transgenic mice conclusively supports the hypothesized role of sex steroids and refutes the suggested role of acute-phase inducers in regulating the apo(a) gene.

Acute-Phase Reaction↗
PubMed1995

The amylose content in rice endosperm is related to the post-transcriptional regulation of the waxy gene.

The waxy (Wx) gene of rice encodes a granule-bound starch synthase (GBSS = waxy protein) required for the synthesis of amylose in endosperm. An analysis of Wx transcripts, Wx protein, and amylose content of 31 rice cultivars revealed that endosperm amylose and Wx protein contents are correlated with the ability of the cultivar to excise intron I from the leader sequence of the Wx transcript. Cultivars with high endosperm amylose content (group I) contain high levels of amylose, Wx protein, and the mature 2.3 kb Wx mRNA. Cultivars with intermediate amylose content (group II) produce substantial amounts of a large 3.3 kb Wx pre-mRNA, with intron I still present, in addition to the mature Wx mRNA, and intermediate levels of Wx protein. Glutinous rice (group III cultivars) contains no amylose, no Wx protein, and no mature Wx mRNA; only the incompletely spliced 3.3 kb Wx pre-mRNA is present in group III cultivars. Based on these results, it is hypothesized that the amylose content of rice endosperm is regulated at the level of Wx transcript processing, and, more specifically, at the stage of intron I excision from the Wx pre-mRNA.

Amino Acid Sequence↗
PubMed1994

Immunocytochemical identification of murine and human megakaryocyte colonies in soft-agar cultures.

Murine megakaryocyte (MK) colonies in soft-agar cultures were immunocytochemically stained with platelet antiserum and an immuno-alkaline phosphatase procedure. Subsequently, cytochemical staining for acetylcholinesterase was used to confirm the specificity of the immunolabelling technique. The correlation of numbers of megakaryocyte colonies enumerated by independent observers was excellent. A comparable platelet antiserum directed against human platelet epitopes was utilized to identify human MK colonies in soft-agar cultures of human bone marrow. Using this method, we determined that the frequency of detectable human MK colonies in our agar culture system was maximal between days 10 and 12. The immunocytochemical staining technique we have developed for identification of MK colonies in soft-agar cultures yielded good cellular morphology and produced an intensely specific label against a clear background; it therefore facilitated accurate enumeration of MK colonies. This non-fluorescent method avoids dependence upon a non-permanent marker, and allows the simultaneous enumeration of positive and negative colonies.

Acetylcholinesterase↗
PubMed1994

[Clinical study of naoxin sutong in the treatment of acute cerebral infarction].

It was shown that the cerebral ischemia-reperfusion produced free radicals are the main factor that causes irreversible cerebral injury. The mechanism of Naoxin Sutong (NXST) treated acute cerebral infarction was elucidated. It is compared with Ligustrazine (LT), which has been proved to be an effective drug for cerebral infarction. The curative effect and the changes of serum malondialdehyde (MDA) levels, blood rheology, blood lipid, etc. of 41 patients with acute cerebral infarction within 3 days, who were confirmed by CT. The therapeutic result showed that after 4 weeks of treatment the points of progress for central nervous system deficit scoring of NXST and LT group were 10.67 +/- 5.02 and 6.85 +/- 4.49 respectively. The difference between these two groups was significant. MDA levels of the patients and the healthy subjects were 6.46 +/- 1.70 and 3.87 +/- 0.67 nmol/ml respectively, the difference was also significant (P < 0.01). After 2 weeks of treatment, MDA content of NXST was less than before (P < 0.05). However the level of LT group did not reduce, while after 3 weeks of treatment, MDA content of NXST group was 4.34 nmol/ml. It was much less than that of LT group and approached that of healthy subjects. Results also showed that blood rheology improved, blood lipid reduced after NXST treatment. All these indicated that the effect of NXST in treating acute cerebral infarction was good, and the mechanism as that NXST could scavenge free radicals, ameliorate cerebral ischemia-reperfusion injury, improve blood rheology and reduce blood lipid.

Acute Disease↗
PubMed1994

[Stereotactic radiosurgery by isocentric linear accelerator].

Stereotactic radiosurgery by isocentric linear accelerator, new technique developed in neurosurgery, was used to treat 92 patients with deeply localized cerebral tumors. Its indications and the techniques of improving its effect, preventing its complication were underlined.

Adenoma↗