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J Q Zhu

Publications and source records attributed to J Q Zhu.

18 recordsLinked to original sources
PubMed1992

Parallel stranded DNA under the scanning tunnelling microscope.

Using scanning tunnelling microscopy, we have directly observed parallel stranded DNA helixes of 43 nucleotides in length. The double helix is right-handed and has an average spacing, 17.43 A (+/- 1 S.D.: 2.30 A), and an average apparent depth, 4.79 A (+/- 1 S.D.: 1.04 A) for each groove. The average pitch of the helical turn is 34 A (+/- 1 S.D.: 3.35 A) and consists of no more than ten base pairs. The diameter of the helix is approx. 17-20 A. Our results provide direct evidence for the existence of a parallel structure of DNA in vitro and some details of its fine structure.

Base Sequence↗
PubMed1992

Molecular dosimetry of urinary aflatoxin-DNA adducts in people living in Guangxi Autonomous Region, People's Republic of China.

Hepatocellular carcinoma is one of the five leading human cancers causing at least 250,000 deaths each year. One of the major risk factors for this disease is exposure to dietary aflatoxins, and the development of appropriate molecular dosimetry biomarkers would facilitate the identification of individuals at risk. This study was undertaken to explore the relationship between dietary intake of aflatoxins and the excretion of the major aflatoxin-DNA adduct and other metabolites into the urine of chronically exposed people. The following protocol was developed for this investigation in Guangxi Autonomous Region, People's Republic of China, where the diets of 30 males and 12 females (ages, 25-64 years) were monitored for 1 week and aflatoxin intake levels determined each day. Starting on the fourth day, total urine volumes were obtained in consecutive 12-h fractions for 3 or 4 days. High performance liquid chromatography and competitive radioimmunoassay analyses were done on each of the urine samples, and the relationships between excretion of total aflatoxin metabolites, aflatoxin-N7-guanine, aflatoxin M1, aflatoxin P1, and aflatoxin B1, and aflatoxin B1 intake values were determined. The average intake of aflatoxin B1 by men was 48.4 micrograms/day, giving a total mean exposure during the study period of 276.8 micrograms. The average daily intake by women was 77.4 micrograms/day, resulting in a total average exposure during the 7-day period of 542.6 micrograms aflatoxin B1. Initial efforts to characterize aflatoxin metabolites in urine samples were with an analysis by competitive radioimmunoassay. The analysis by linear regression of the association between aflatoxin B1 intake/day and total aflatoxin metabolite excretion/day showed a correlation coefficient of only 0.26. These findings stimulated the immunoaffinity/analytical high performance liquid chromatography analysis for individual metabolites. When the data were analyzed by linear regression analysis, the aflatoxin N7-guanine excretion and aflatoxin B1 intake from the previous day showed a correlation coefficient of 0.65 and P less than 0.000001. Similar analysis for aflatoxin M1 resulted in a correlation coefficient of 0.55 and P less than 0.00001, whereas there was no positive statistical association between exposure in the diet and aflatoxin P1 excretion, despite aflatoxin P1 being quantitatively a major metabolite. Analysis of the total aflatoxin-N7-guanine excretion in the urine during the complete collection period plotted against the total aflatoxin B1 exposure in the diet for each of the individuals, smoothing the day to day variations, revealed a correlation coefficient of 0.80 and P less than 0.0000001.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Selective inhibition of normal murine myelopoiesis "in vitro" by a Hox 2.3 antisense oligodeoxynucleotide.

Multiple homeobox genes are expressed in haematopoietic cell lineages and their expression is cell-type specific. Thus we hypothesized that certain homeobox genes may play an important role in the process of haematopoiesis. To prove that issue, normal murine bone marrow cells were stimulated with appropriate Colony Stimulating Factors in the presence of mouse homeobox gene (Hox 2.3) sense or antisense oligodeoxynucleotides and the effects on the haematopoietic colony formation were examined. Treatment of the cells to Hox 2.3 antisense oligodeoxynucleotides led to a selective inhibition of myeloid colony formation, both in size and in numbers, but without significant effect on erythroid and megakaryocytic haematopoiesis. Exposure to Hox 2.3 sense oligodeoxynucleotides (no-oligomers), had no such effect. It was further showed that inhibition of myelopoiesis by Hox 2.3 antisense oligodeoxynucleotides was dependent on the differentiation stage of target cells. These findings demonstrated that Hox 2.3 gene plays a critical role in regulating normal murine myelopoiesis.

Animals↗
PubMed1992

Protective and anti-arrhythmic effects of dauricine and verapamil on acute myocardial infarction in anesthetized dogs.

Dauricine (Dau) 5 mg.kg-1 and verapamil (Ver) 0.15 mg.kg-1 iv followed by infusions of 0.1 and 0.01 mg.kg-1.min-1, respectively, for 30 min, depressed the elevated coronary venous blood LDH and CPK after LAD occlusion. Dau produced antagonistic effects on acute myocardial ischemia-induced ventricular ectopic activities (VE) and ventricular tachycardia (VT). The incidences of VE and VT in Ver group and ventricular fibrillation (VF) in both groups tended to descend. The results suggested that Dau and Ver produced marked protective effects on myocardial infarction and antagonized the acute ischemic arrhythmia.

Alkaloids↗
PubMed1991

The effects of Chinese tea on the methylation of DNA by the esophageal carcinogen N-nitrosomethylbenzylamine.

In order to investigate the mechanisms of the anticarcinogenic effect of Chinese tea on the development of esophageal tumors in rats induced by N-nitrosomethylbenzylamine, the alkylation of DNA in various organs was studied in rats treated with 2 varieties of Chinese tea, i.e. Fujian Oolong tea and Jasmine tea. Male Wistar rats were given a single i.v. injection of N-nitroso-[methyl-14C]-benzylamine (2.5 mg/kg body wt) after having been provided tea in drinking water and by gavage for 2-3 weeks. Control rats were provided with tap water. Three to four hours after administration of the N-nitroso compound, the methylation of purine bases in the DNA isolated from various organs was measured by high performance liquid chromatography and liquid scintillation counting. In the tea-drinking rats, there was an appreciable reduction of O6-methylguanine formation in the esophageal DNA as well as the ratio of O6-methylguanine to N7-methylguanine, as compared to the control rats. No O6-methylguanine was detected in lung or liver DNA.

Animals↗
PubMed1991

Recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) induces human macrophage production of transforming growth factor-alpha.

Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is known as an inducer of proliferation and functional activation of myeloid cells. This study was carried out to characterize the effect of purified recombinant human GM-CSF (rhGM-CSF) on induction of TGF-alpha in macrophages. Using Northern blot analysis and immunoassays, we show here that rhGM-CSF markedly stimulates production of TGF-alpha messenger RNA and protein in normal tonsil macrophages. The findings are consistent with macrophages being a normal inducible source of TGF-alpha which may be an important mediator of various activities of GM-CSF both in hematopoietic and non-hematopoietic cells.

Animals↗
PubMed1990

The regulatory effects of macrophages on colony stimulating factor-1 (CSF-1) production.

1. By using the anti-sense oligodeoxynucleotide inhibition strategy, we demonstrated that the production of CSF-1 by macrophage was blocked specifically by a CSF-1 anti-sense oligodeoxynucleotide complementary to the 5' end of the coding region of mouse CSF-1 m-RNA transcripts, but not by the CSF-1 mRNA transcripts, but not by the CSF-1 sense oligomer. 2. The LPS-induced condition medium of macrophages treated with CSF-1 anti-sense oligodeoxynucleotide retained the capacity of stimulating mouse fibroblast cells and bone marrow cells producing CSF-1 in vitro. 3. In addition to the inhibition of CSF-1 production by macrophages CSF-1 anti-sense oligodeoxynucleotide also inhibited the CSF-1 production of fibroblast cells and bone marrow cells stimulated by the macrophages conditioned medium. 4. These results suggest that macrophages stimulate their own development by mediating CSF-1 production at least in three ways: (1) production CSF-1; (2) stimulating fibroblast cells; (3) bone marrow cells to produce CSF-1. There is a positive feedback mechanism for macrophage hematopoiesis and its functional expression.

Animals↗
PubMed1990

Effects of dauricine and lidocaine alone or combined on electrophysiological properties of canine Purkinje fibers.

Dauricine (Dau) 1 to 30 mumol/L produced the concentration-dependent depressions in the APA, Vmax, MDP, and prolongations of APD50 and APD90 as well as ERP of the isolated canine cardiac Purkinje fibers (PF). The automaticity and excitation were significantly reduced at concentration of 30 mumol/L. The effects of Dau on all action potential parameters of PF were observed at all stimulation frequencies (60, 75, 100, 150 beats/min). Lidocaine (Lid) markedly shortened APD50 of PF at concentration of 30 mumol/L and also shortened APD90, ERP and significantly depressed APA, Vmax at 100 mumol/L. When perfused in combination with Dau, Lid appreciably shortened APD50 and APD90, and lightly abbreviated ERP prolonged by Dau.

Action Potentials↗
PubMed1990

Effects of dauricine on transmembrane potential of ischemic and non-ischemic Purkinje fibers and ventricular muscles from infarcted canine hearts.

Dauricine (Dau) 1-30 mumol/L produced the concentration-dependent depression of APA, Vmax, MDP, and RP, and prolongations of APD90 of Purkinje fibers (PF) and epicardial ventricular muscles (VM) from both infarcted and non-infarcted zones. The ERP was lengthened only in non-ischemic PF and VM, and APD50 in non-ischemic PF, non- and ischemic VM. The prolonging effects of Dau on APD and ERP of ischemic PF were much less than those of non-ischemic ones, and its depressing effect on the Vmax of ischemic VM was markedly greater than that of non-ischemic VM. The results suggest that Dau exerts its anti-arrhythmic effect through further depressing conduction of ischemic zone.

Action Potentials↗
PubMed1990

The role of the c-fms oncogene in the regulation of HL-60 cell differentiation.

Human promyelocytic leukemia HL-60 cells were induced to differentiate into macrophages by PMA (phorbol 12-myristate-13-acetate), 1-alpha-25-(OH)2D3(1-alpha-25-dihydroxyvitamin D3, hrGM-CSF (human recombinant granulocyte-macrophage colony-stimulating factor) and into granulocytes by DMSO (dimethylsulfoxide). We found that the differentiation of HL-60 cells into macrophages was accompanied by transcription of the c-fms oncogene, which was assessed by a modified PCR (polymerase-chain reaction) method. After treatment with a c-fms anti-sense oligomer, the PMA and hrGM-CSF induced macrophage differentiation of HL-60 cells was significantly inhibited, whereas either 1-alpha-25-(OH)2D3 induced macrophage or DMSO and hrGM-CSF induced granulocytic differentiation was not inhibited. Furthermore, we treated the HL-60 cells with M-CSF (macrophage-colony stimulating factor or CSF-1) anti-sense N degrees 2 (see Figure 1) in the presence of PMA, hrGM-CSF, 1-alpha-25-(OH)2D3 and DMSO. The results showed that this treatment leads to a significant inhibition of PMA and hrGM-CSF-induced macrophage differentiation, but has no influence on the 1-alpha-25-(OH)2D3-induced macrophage differentiation and DMSO-induced granulocytic differentiation. It was further demonstrated that the M-CSF (or CSF-1) and c-fms antisense oligomers acted synergistically on inhibition of macrophage formation induced by PMA and hrGM-CSF, but had no inhibitory effect on the macrophage formation induced by 1-alpha-25-(OH)2D3. Thus we concluded firstly, that HL-60 cells differentiate into macrophages along two different pathways: one is involved in the action of the c-fms oncogene and the other is not. Secondly, an autocrine circuit of M-CSF (or CSF-1) action may exist in the macrophage formation induced by PMA and hrGM-CSF.

Base Sequence↗
PubMed1990

[Effects of dauricine on His-bundle electrogram and interaction with other drugs in anesthetized rabbits].

Dauricine was shown to prolong the HBE A-H, H-V intervals and the V width of anesthetized rabbits in a dose-dependent manner. Dauricine 2.5, 5 and 7.5 mg/kg iv increased the A-H interval by 11 +/- 6, 21 +/- 12 and 33 +/- 14%; prolonged the H-V interval by 22 +/- 9, 34 +/- 22 and 51 +/- 16%; and widened the V by 14 +/- 6, 22 +/- 12 and 27 +/- 11%, respectively. The effect of dauricine on the H-V interval was greater than on the A-H interval. Influence of lidocaine on the His-bundle electrogram was not significant. The effect of dauricine on the H-V interval was weakened when administered in combination with lidocaine (p less than 0.05). Dauricine 7.5 mg/kg prolonged the A-H interval at all stimulation frequencies (300, 335, 375, 430 beats/min). Dauricine increased the atrial effective refractory period (AERP) and the atrial-ventricular (A-V) node functional refractory period (AVNFRP) of the rabbits in dose-dependent manner. Isoprenaline 10 micrograms/kg iv shortened the A-H, H-V intervals and V width, and atropine 3 mg/kg iv partially reduced the A-H interval prolonged by dauricine.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed1987

Correlation of dietary aflatoxin B1 levels with excretion of aflatoxin M1 in human urine.

Corn and peanut oil (total, 253 samples) were collected from 32 households in Fushui county of the Guangxi autonomous region of the People's Republic of China, where high liver cancer incidence has been reported, every day over a period of 1 week and analyzed for aflatoxin B1 (AFB). A total of 252 urine samples were collected simultaneously from the residents in the households which were shown to have consumed AFB and were analyzed for aflatoxin M1 (AFM) by a competitive direct enzyme-linked immunosorbent assay. A good correlation between total dietary AFB intake and total AFM excretion in human urine was observed during a 3-day study. A regression equation of 0.143 plus 0.0135 multiplied by the amount of AFB consumed was observed. Between 1.23 and 2.18% of dietary AFB was found to be present as AFM in human urine. A good correlation was also observed between the AFB concentration in corn and the AFM concentration in human urine. The results suggest that analysis of AFM in urine by enzyme-linked immunosorbent assay could be used as an index for human exposure of AFB in an extensive epidemiological study.

Aflatoxin B1↗
PubMed1985

Aflatoxin metabolism in humans: detection of metabolites and nucleic acid adducts in urine by affinity chromatography.

A high-affinity IgM monoclonal antibody specific for aflatoxins was covalently bound to Sepharose 4B and used as a preparative column to isolate aflatoxin derivatives from the urine of people and experimental animals who had been exposed to the carcinogen environmentally or under laboratory conditions. Aflatoxin levels were quantified by radioimmunoassay and high-performance liquid chromatography after elution from the affinity column. In studies on rats injected with [14C]aflatoxin B1, we identified the major aflatoxin-DNA adduct, 2,3-dihydro-2-(N7-guanyl)-3-hydroxy-aflatoxin B1 (AFB1-N7-Gua), and the oxidative metabolites M1 and P1 as the major aflatoxin species present in the urine. When this methodology was applied to human urine samples obtained from people from the Guangxi Province of China exposed to aflatoxin B1 through dietary contamination, the aflatoxin metabolites detected were also AFB1-N7-Gua and aflatoxins M1 and P1. Therefore, affinity chromatography using a monoclonal antibody represents a useful and rapid technique with which to isolate this carcinogen and its metabolites in biochemical epidemiology and for subsequent quantitative measurements, providing exposure information that can be used for risk assessment.

Aflatoxin B1↗