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Biomedical subjects

J Z Li

Publications and source records attributed to J Z Li.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Assessment of malaria DNA vaccines in mice and monkeys].

Cholera toxin B subunit is a good carrier protein and an effective adjuvant which can boost both cellular and humoral immunity. DNA fragments encoding B cell, Th cell and CTL epitopes of P. falciparum CS, MSA-1, MSA-2 and RESA antigens were cloned down-2 stream of cholera toxin B subunit gene in the same reading frame. High titer of anti-malaria epitopes antibodies and strong cellular immunogenicity were elicited after Balb/c mice were immunized three times with 100 micrograms recombinant plasmid DNA dissolved in 100 microliters PBS. A total of 120 vaccinees were challenged with mouse Plasmodium yoelli to investigate if cross protection existed. The protective efficacy was about 60%-80%. Four rhesus monkeys were challenged with 10(8) of P. cynomalgi, better results were obtained in the groups immunized with mixed plasmids including NANP, AWTE.

Animals↗
PubMed2000

[Application of microsatellite markers for the seed purity examination of a hybrid rice, Gangyou-22].

For seed commercialization of hybrid rice it is necessary to examine the purity of its seeds before field-production, because the seed purity is closely related to their heterosis performance and yield increase. In this research, 160 microsatellite markers were used for PCR amplification of rice seedling DNAs of Gangyou-22, which is a major hybrid rice in China, and its parents, Gang46A(CMS line) and CDR22(restorer line). A microsatellite marker, RM168, was screened out for its ability to produce polymorphic bands specific to each of the two parents but different from other 22 restorer lines and 9 cultivars. This provides an accurate and efficient method to examine the purity of a hybrid rice at an earlier time. Amplification of DNAs extracted from seeds and application of two microsatellite markers in one PCR system can further simplify the procedure and improve the accuracy of the seed purity examination.

Hybridization, Genetic↗
PubMed2000

[Translation initiation function of the regulation element in the operon of cholera toxin A].

To demonstrate that there existed translation coupling between cholera toxin A subunit gene and B subunit gene, and give the answer why the expression level of B gene is five times more than that of A gene, alpha report system for the investigation of translation coupling was constructed by using lacZ gene as reporter. Frame-shift mutation was introduced near the C terminal of ctxA gene, and the ribosome would read through its normal stop codon. The report plasmid was constructed and it was found that the expression level of lacZ gene decreased five times after the frame-shift mutation. The translation of cholera toxin B subunit gene was translational coupled with A subunit gene, and was responsible for the differential expression level of the two genes.

Cholera Toxin↗
PubMed2000

[A new model of translational control of gene expression in polycistron++ of AB5 entrerotoxin].

The expression level of the B subunit gene of cholera toxin (ctx) and E. coli heat labile toxin (ltx) is five to seven times more than that of A subunit gene. In these studies, a 80 basepair translation regulation element was found located in the structure gene of A gene of both toxin operon which consists of three translation initiation region. Site-directed mutation of the initiation codon of TIR3 resulted in the 9 time decrease of the expression of the downstream cistron which was translational coupled with A gene. The results indicated that translation from the internal of A gene and translation coupling are responsible for the differential expression level of the A and B gene of AB5 enterotoxin.

Bacterial Toxins↗
PubMed2000

[Induction of protective immune response in mice and rhesus monkeys by immunization with fusion protein of cholera toxin B subunit and multiples of Plasmodium falciparum].

Recombinant fusion protein of cholera toxin B subunit (CTB) and poly-valent protective epitopes of plasmodium falciparum was given to i.m. to C57BL/6j mice and rhesus monkeys three times. In rhesus monkeys, high level of antibodies for CTB (1:6400) and malaria epitopes (1:3200) amtobpdoes were elicited as well as the specific CTL activity for P. plasmodium. After the mice were challenged with sporozoites of P. yeolli, about 50% of them were protected from the patent infection. A blood-stage challenge with 10(8) of P. cynomolgi parasite were given to rhesus monkeys, which showed that two animals in control group were patent infection for at least 30 days, in contrast, the two animals immunized were recovered respectively at the day of 11 and 15 after challenges. The results suggested that cholera toxin acts as an effective adjuvent in the development of malaria vaccine.

Animals↗
PubMed1999

[Study on gene-dosage effect of high level expression of the yeast glucoamylase genes].

Diploid strains homozygous for both MAT allele and STA genes (a/a, STA1/STA1 or STA2/STA2 or STA3/STA3) and diploid strains homozygous for MAT allele but intercombinative for STA genes (a/a, STA1/STA2 or STA2/STA3 or STA1/STA3) were constructed by means of the protoplast fusion or the colchicine treatment. According to glucoamylase activity in YPS medium, we studied the gene-dosage effect and their interrelation of these three polymeric genes coding for glucoamylase. The results of the glucoamylase activity determination showed that the gene-dosage effect of glucoamylase is obvious in diploid and triploid strains homozygous for both MAT allele and STA gene, such as the glucoamylase activity of a diploid strain SFY56-6 and a triploid strain SFY56-104 homozygous for both MAT allele and STA genes were respectively 2.35 and 3.18-fold as compared with that of the their parental strain IATA-Y56 that is a haploid Saccharomyces diastaticus. Moreover, the glucoamylase activity of diploid strains homozygous for MAT allele but intercombinative for STA genes also showed the combinative gene-dosage effect to a certain extent.

Gene Dosage↗
PubMed1998

TNF-alpha increases albumin permeability of isolated rat glomeruli through the generation of superoxide.

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine that plays a central role in inflammation. Glomerular levels of TNF-alpha are elevated in human and experimental glomerulonephritis. Glomerular cells produce and respond to TNF-alpha. One of the mechanisms by which these cells respond to TNF-alpha is through generation of reactive oxygen species. In this study, the effect of TNF-alpha on albumin permeability (P(albumin)) of isolated rat glomeruli and the possible mechanism of this effect were examined. Isolated rat glomeruli were incubated with TNF-alpha (0.4 ng/ml), TNF-alpha with anti-TNF-alpha antibodies, and TNF-alpha with the reactive oxygen species scavengers superoxide dismutase, catalase, DMSO, or dimethylthiourea for 12 min at 37 degrees C, and P(albumin) was calculated. TNF-alpha increased P(albumin) of isolated glomeruli compared with control (0.70 +/- 0.02, n = 25 versus 0.00 +/- 0.05, n = 26), and this effect was abrogated by anti-TNF-alpha antibodies (-0.18 +/- 0.05, n = 23). Superoxide dismutase abolished the increase in P(albumin) (-0.04 +/- 0.11, n = 23), whereas catalase (0.73 +/- 0.08, n = 30), DMSO (0.64 +/- 0.03, n = 10), or dimethylthiourea (0.51 +/- 0.08, n = 10) did not alter the effect of TNF-alpha. These results indicate that TNF-alpha increased P(albumin+)++ of isolated glomeruli and that the mediator of the increased P(albumin) is superoxide. It is concluded that TNF-alpha derived from glomerular or extraglomerular sources can increase glomerular P(albumin) through generation of superoxide and may lead to proteinuria.

Administration, Topical↗
PubMed1997

The activation of human platelets mediated by two monoclonal antibodies raised against CD9.

The platelet activation induced by two anti-human platelet P24/CD9 McAbs was investigated. The results showed that: the pathway of platelet aggregation induced by the two McAbs (HI117 and SJ9A4) is not the same; HI117 and SJ9A4 induced the phosphorylation of platelet proteins (40KD and 20KD) when platelets were activated; but HI117 didn't cause a rise in intracellular Ca2+ concentration in activated platelets compared with SJ9A4; the epitope recognized by HI117 and SJ9A4 is different and this is probably the real reason why the two CD9 McAbs play different roles in platelet activation. Additionally McAbs HI117 and SJ9A4 could not promote associates of other proteins (e.g.: GPIIb/IIIa) with P24/CD9 on activated human platelets. All these results indicate that the mechanism of platelet activation induced by HI117 or SJ9A4 is different form each other. It suggests that CD9 antigen play an important and complex role in platelet activation.

Antibodies, Monoclonal↗
PubMed1997

Inhibitory effect of Tripterygium wilfordii multiglycoside on increased glomerular albumin permeability in vitro.

BACKGROUND: Tripterygium wilfordii Hook F is a medicinal plant used for the treatment of glomerulonephritis in China. We studied the effect of Tripterygium wilfordii multiglycoside (TWG) on glomerular albumin permeability (Palbumin) in vitro. METHODS: Isolated rat glomeruli were incubated with protamine (600 micrograms/ml) for 30 min, or with human recombinant tumour necrosis factor (TNF-alpha 0.4 ng/ml), superoxide (10 units/ml), or serum from a focal segmental glomerular sclerosis (FSGS) patient for 10 min at 37 degrees C. TWG, 1 mg/ml, was added in parallel tubes to study the effect on Palbumin. Control glomeruli were incubated under identical conditions. The albumin reflection coefficient (sigma albumin) was calculated from the change in glomerular volume in response to an applied oncotic gradient. Convectional permeability (Palbumin) was calculated as (1 - sigma albumin). RESULTS: Compared with controls, protamine increased the Palbumin of glomeruli (0.83 +/- 0.05, n = 25, vs 0.18 +/- 0.03, n = 20); pretreatment with TWG blocked this effect (0.13 +/- 0.04, n = 25). TNF-alpha also increased the Palbumin (0.79 +/- 0.04, n = 24 vs 0.04 +/- 0.07, n = 19); preincubation with TWG blocked this effect (0.03 +/- 0.09, n = 24). Palbumin of glomeruli incubated with xanthine and xanthine oxidase, resulting in the production of superoxide, also increased as compared to controls (0.85 +/- 0.04, n = 15 vs 0.08 +/- 0.05, n = 14); TWG blocked this effect as well (0.21 +/- 0.08, n = 14). FSGS serum also increased Palbumin of glomeruli significantly (0.88 +/- 0.02, n = 49 vs 0.00 +/- 0.02, n = 49); preincubation with TWG blocked this effect (0.05 +/- 0.07, n = 30). TWG by itself had no effect on Palbumin (0.19 +/- 0.10, n = 15). CONCLUSIONS: Our results show that TWG blocks protamine, TNF-alpha, superoxide, and FSGS serum-mediated increase in glomerular albumin permeability in vitro. We conclude that reduction of proteinuria by Tripterygium wilfordii multiglycoside in various kinds of glomerular diseases in vivo might be due to protection of the glomerular filtration barrier.

Animals↗
PubMed1997

Direct effects of platelet-activating factor on glomerular capillary permeability.

Platelet-activating factor (PAF) is an important mediator of injury in acute renal failure and glomerulonephritis. Intrarenal infusion of PAF reduces glomerular filtration rate and renal plasma flow and increases glomerular permselectivity via its renal hemodynamic and/or immunologic effects. Direct effects of PAF on glomerular capillary permeability are not known. We studied the direct effects of PAF on mesangial contraction (a measure of filtration area), glomerular capillary hydraulic conductivity (L[p]) and capillary albumin permeability (P[albumin]). Glomeruli were isolated from Sprague-Dawley rats and incubated with or without various concentrations of PAF (10[-9], 10[-7] and 10[-5] M) for up to 5 h at 37 degrees C. Mesangial contraction (percent change in glomerular volume) was assessed from the gradual decrease in volume of glomeruli during 20 min of incubation with PAF. L(p) was calculated from the rate of change in glomerular volume during the 0.1 s of capillary expansion in response to a transcapillary oncotic gradient. P(albumin) was calculated from a change in relative volume of glomeruli in response to an oncotic gradient. Mesangial contraction was maximal after 20 min of incubation and was concentration dependent (5.2+/-0.9, 7.9+/-1.0 and 10.0+/-1.0%, respectively, with PAF 10(-9), 10(-7) and 10(-5) M). Incubation of glomeruli with PAF 10(-7) M for 60 min at 37 degrees C caused a significant decrease in L(p) (2.25+/-0.30 vs. control 3.12+/-0.28 microl x min(-1) x mm Hg(-1) x cm(-1), n = 5). P(albumin) of glomeruli incubated with PAF was unchanged up to 2 h but increased significantly with the highest concentration of PAF (10(-5) M) after 3 h of incubation (0.60+/-0.18, n=15, vs. control 0.00+/-0.08, n = 20), whereas lower concentrations of PAF (10[-7] or 10[-9] M) required at least 5 h of incubation with glomeruli to cause a significant increase in P(albumin) (0.45+/-0.09 and 0.48+/-0.07, respectively, n=15, vs. control 0.00+/-0.08, n=15). We conclude that PAF has multiple direct effects on glomerular functions, which are time dependent and may contribute to the altered capillary permeability in vivo.

Albumins↗
PubMed1997

[Effect of Astragalus Angelica mixture on serum lipids and glomerulosclerosis in rats with nephrotic syndrome].

OBJECTIVE: To confirm the renal protective action of Astragalus Angelica mixture (AAM). METHODS: Effect of AAM was observed in puromycin amino-nucleoside induced nephrotic syndrome model of rat, and pravachol, an effective lipid lowering medicine, was used as positive control. RESULTS: AAM could not only reduce the serum levels of total cholesterol and triglyceride as pravachol did, but also could lower levels of low density lipoprotein and apolipoprotein B100 (P < 0.05). Light microscopic and immuno-histochemical examination revealed that in the same time of lowering serum lipids, this mixture could also cause reduction of glomerular sclerosing index (P < 0.01) and less accumulation of extracellular matrix (P < 0.01). CONCLUSIONS: AAM has the effects of regulating lipid metabolism, attenuating renal damage and maintaining renal function in rats with nephrotic syndrome.

Animals↗
PubMed1997

[The preliminary results of prevention and treatment in the population of patients with COPD and cor pulmonale].

UNLABELLED: This paper tends to evaluate the effects of comprehensive prevention and treatment in COPD and cor pulmonale in the communities. A Randomized cohort with stratified design was undertaken in the rural areas with hundred thousand population in Beijing municipality, Lianning and Hubei Provinces, from spring 1992 to spring 1995. RESULTS: (1) the rates to all stratified populations under management were 85.6% among those with high risk, 87.8% among COPD and 83.6% among cor pulmonale, respectively. (2) The levels of KAB were raised more significantly in most intervention group than in control group which up +9.6% to +33.6% and -5.8% to +32.6%, respectively. (3) Comparisons between the two groups revealed: 1. Number of cigarette smokers who smoked more than before increased (20.1% vs 17.8%) but with no statistical significance. 2. The rate of smoking cessation went higher (15.5% vs. 11.3%, P < 0.01). 3. New high risk subjects were reduced (2.8% vs 3.9%, P < 0.01). 4. Number of new cor pulmonale patients decreased (19.9% vs 22.6%, P > 0.05) and mortality rate lowered (4.34% vs 4.78%, P > 0.05). CONCLUSION: preliminary results indicates that the active intervention is effective in reducing COPD and cor pulmonale among population at high risk in communities. However, it is necessary to point out that COPD and cor pulmonale are both having chronic nature which calls for patient and continuous efforts.

Adolescent↗
PubMed1996

The role of intra- and extragranular microcrystalline cellulose in tablet dissolution.

The objective of this study was to examine the influence of intra- and extragranular microcrystalline cellulose (MCC) on drug dissolution from tablets made by high-shear granulation. Granulations were made in a Littleford Model W-10-B (10-liter) mixer and dried in a fluid bed dryer (Niro Inc.). A Plackett-Burman screening design and 2(3) factorial design were employed to study how drug type, MCC (intra- or extra-), filler type (lactose or dicalcium phosphate), disintegrant type (sodium starch glycolate or croscarmellose sodium) and level, proportion of magnesium stearate, and impeller speed affect tablet hardness, disintegration time, and dissolution. Two model drugs were chosen based on their solubility: metoprolol tartrate (solubility > 1000 mg/ml) and hydrochlorothiazide (solubility = 1.05 mg/ml). Tablets were compressed to the same target weight (dose) and similar tablet hardness. In some cases, dissolution testing was also carried out on the loose granules. The intra-extragranular distribution of MCC was found critical to the compactibility and initial dissolution rates from these tablets. Intragranular MCC reduced drug dissolution, the effect being most marked in the case of the slightly soluble hydrochlorothiazide. For formulations containing intragranular MCC, the granulating fluid level on tablet dissolution was also important, since an increase in fluid level resulted in slower drug dissolution from both the loose granules and the tablets compressed from them. Conversely, extragranular MCC tended to increase both dissolution rates and compactibility. It may be concluded that the appropriate distribution of MCC between and within granules may optimize both dissolution and compactibility without changing overall tablet composition.

Cellulose↗
PubMed1995

Sodium nitroprusside increases glomerular capillary hydraulic conductivity in isolated rat glomeruli.

Sodium nitroprusside (SNP) causes renal vasodilation, increased renal blood flow, and increased renal sodium excretion. Systemic vascular effects of SNP are dependent on generation of nitric oxide and increase in smooth muscle intracellular cyclic guanosine monophosphate (cGMP). In the current studies isolated glomeruli were used to determine the effects of SNP on glomerular capillary hydraulic conductivity (Lp) and on mesangial tone. The direct effects of the cGMP analogue 8-bromo-cGMP on Lp were studied. Glomeruli were isolated from the superficial renal cortex of adult male Sprague-Dawley rats weighing 143 to 383 gm. Lp was calculated from videomicroscopic images of individual glomeruli during the initial 0.1 second of filtration induced by an albumin oncotic gradient. Incubation of glomeruli in 10(-3) mol/L SNP increased Lp from a control value of 1.38 +/- 0.08 microliter/min.mm Hg.cm2 to 1.91 +/- 0.13 microliter.min.mm Hg.cm2 (p < 0.01). Incubation of glomeruli in 10(-5) mol/L 8-bromo-cGMP increased Lp to a comparable degree from a control value of 2.00 +/- 0.58 microliter/.min.mm Hg.cm2 to 2.39 +/- 0.62 microliter/min.mm Hg.cm2 (p < 0.03). Increase in Lp was observed independent of any effects on systemic or renal circulations, neural effects, or humoral effects. Changes in mesangial tone were estimated from changes in glomerular volume during 15 minutes of incubation with SNP or control medium. Incubation of glomeruli in 10(-5) mol/L SNP increased glomerular volume 6%, a consequence of mesangial relaxation. Incubation of glomeruli in 10(-7) and 10(-3) mol/L SNP did not affect mesangial tone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Polymorphonuclear leukocytes increase glomerular albumin permeability via hypohalous acid.

Acute glomerulonephritis is characterized by the presence of neutrophils within glomeruli and the generation of reactive oxygen species (ROS) by activated polymorphonuclear leukocytes (PMNs). Hydrogen peroxide (H2O2) and other ROS including hypothalous acids have been implicated in PMN mediated injury. To determine the role of specific ROS in PMN mediated glomerular injury, isolated rat glomeruli were incubated for 30 minutes at 37 degrees C with H2O2, with H2O2 and myeloperoxidase, or with activated PMNs. Scavengers of ROS were included in some experiments. PMNs were harvested from rat peritoneal cavity and activated with phorbol myristate acetate (PMA). Glomerular albumin permeability (Palbumin) was calculated from the volume response to an oncotic gradient. Palbumin of glomeruli incubated with H2O2 (10(-3) or 10(-1) M) was not increased, while Palbumin after incubation with H2O2 and MPO was markedly increased (0.94 +/- 0.004). Palbumin after incubation with PMA, or with non-activated PMNs was not different from that of control glomeruli, Palbumin of the glomeruli incubated with activated PMNs increased (0.85 +/- 0.01, P < 0.001). This increase in Palbumin was inhibited by superoxide dismutase, catalase, or taurine (Palbumin = 0.035 +/- 0.06, -0.39 +/- 0.10, 0.028 +/- 0.06, respectively) and ameliorated by sodium azide (Palbumin = 0.21 +/- 0.03). In contrast, dimethyl sulfoxide did not prevent the increase in Palbumin (Palbumin = 0.92 +/- 0.01). Our results show that the hypohalous acid derived from that of H2O2-MPO-halide system is capable of increasing Palbumin. We conclude that hypohalous acid may be the primary mediator of the immediate increase in glomerular protein permeability induced by PMNs.

Albumins↗
PubMed1994

Effects of endothelin-1 on isolated uterine horns in estrogen-primed and pregnant mice.

Mouse uterine horns from 4 states (estrogen-primed and early-, mid-, and late-pregnancy) were used to study the effect of endothelin-1 (ET) vs carboprost (Car) and oxytocin (Oxy). In K(+)-Krebs (KCl 40 mmol.L-1) solution, ET (1-300 nmol.L-1), Car (0.002-20 mumol.L-1), and Oxy (0.6-60 nmol.L-1) evoked concentration-dependent increases in tension of the uterine horns from 4 different states. Emax for ET were 1.12 +/- 0.26, 1.27 +/- 0.18, and 1.49 +/- 0.13 g in early-, mid-, and late-pregnancies, respectively. Emax for Car in mid- was twice that in late-pregnancy, whereas Emax for Oxy in late- was thrice that in mid-pregnancy. EC50 for ET were 9.6, 5.8, and 6.3 nmol.L-1 in early-, mid-, and late-pregnancies, respectively, and were only 2% to 7% of that for Car and 3-15 times of that for Oxy in various gravid stages. The results suggest that the contractile activity of pregnant mouse uterus to ET is more potent than that of Car while slightly weaker than that of Oxy.

Animals↗