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S L Zhang

Publications and source records attributed to S L Zhang.

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

[Growth and metabolism of hybridoma cells in semicontinuous perfusion cultures].

The growth and metabolism of WuT3 hybridoma cells were studied in semicontinuous perfusion cultures. The growth of cells, utilization of glucose, production of lactate, ammonia and monoclonal antibody were investigated. As the perfusion rate increased from 1.0/d to 2.0/d, the lactate yield coefficient from glucose Ylac/glu decreased 18%, the ammonia yield coefficient from glutamine Yamm/gln decreased 40%, the alanine yield coefficient from glutamine Yala/gln increased 58%, the glycine yield coefficient remained almost constant. This indicate that cells would regulated their metabolic flux at higher cell density, and glutamate produced in quantity and pyruvate would turn into alanine rather than glycine by transamination. As a result, potentially toxic effects were reduced because less ammonia and lactate were produced.

Amino Acids↗
PubMed2000

[Study of the factors of Cr(III) bioaccumulation on Spirulina platensis].

Some factors of Cr(III) bioaccumulation on Spirulina platensis were studied in detail. It was found that the bioaccumulation of Cr(III) on Spirulina platensis involved two steps: rapid adsorption and slow absorption. Chromic(III) compounds with weaker chemical bond had higher bioaccumulation efficiency. Under the same algal cell concentration, Cr(III) bioaccumulation rosed up with Cr(III) concentration. On the other hand, with Cr(III) concentration not changed, the total bioaccumulation of Cr(III) on Spirulina platensis increased with algal cell concentration, but the Cr(III) bioaccumulation on unit algae reduced. The study also showed that Spirulina platensis powder could bioaccumulate more Cr(III) than fresh Spirulina platensis, pH is a quite important factor and more suitable pH for Cr(III) bioaccumulation is 7. It was also proved that Cr(III) bioaccumulation benefited from the increase of temperature and light intensity. Cations had either stimulation or inhibition effects on the Cr(III) bioaccumulation on Spirulina platensis.

Bacterial Proteins↗
PubMed2000

[Advances of studies on enclosed photobioreactors].

In the last two decades, enclosed photobioreactors have received major research attention. It is one of the key techniques in microalgae biotechnology. This article reviews the system development of enclosed photobioreactors which are divided into column, tubular plate and opticle fibre type respectively. Typical photobioreactors of tubular and plate type are introduced separately. Their technical parameters are table compared. The technical development tendencies are summarized.

Bioreactors↗
PubMed2000

[Mixotrophic cultivation of Synechocystis sp. 6803: influences of light intensity and glucose].

The growth characteristics and the effects of glucose and light on the growth of Synechocystis sp. PCC6803 under mixotrophic conditions have been investigated. An exponential growth phase had been observed before glucose was consumed. The results showed that both of light intensity and glucose concentration had obvious effects on the mixotrophic growth of Synechocystis sp. PCC6803: the specific growth are decreased with the increase of glucose concentration at light; the specific growth rate and biomass/glucose yield increased with light intensity, ranging from 15-55 microE.m-2.s-1; when light intensity was higher than 55 microE.m-2.s-1, light saturation appeared.

Carbon Dioxide↗
PubMed2000

Catecholamines and angiotensinogen gene expression in kidney proximal tubular cells.

To investigate the molecular mechanism(s) of action of catecholamines on the expression of the angiotensinogen (ANG) gene in kidney proximal tubular cells, we used opossum kidney (OK) cells with a fusion gene containing the 5'-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (rANG N-1498/+18), permanently integrated into their genomes. The level of expression of the ANG-GH fusion gene was quantified by the amount of immunoreactive-hGH (IR-hGH) secreted into the medium. The addition of norepinephrine (NE), isoproterenol (a beta1/beta2-adrenergic receptor (AR) agonist) and iodoclonidine (an alpha2-AR agonist) stimulated the expression of the ANG-GH fusion gene in a dose-dependent manner, whereas the addition of epinephrine and phenylephrine (alpha1-AR agonist) had no effect. The stimulatory effect of NE was blocked by the presence of propranolol (beta-AR blocker), atenolol (beta1-AR blocker), yohimbine (alpha2-AR blocker), Rp-cAMP (an inhibitor of cAMP-dependent protein kinase AI & AII) and staurosporine (an inhibitor of protein kinase C), but was not blocked by ICI 118, 551 (beta2-AR blocker) and prazosin (alpha1-AR blocker). The addition of a combination of isoproterenol and iodoclonidine or a combination of 8-Bromo-cAMP (8-Br-cAMP) and phorbol 12-myristate (PMA) synergistically stimulated the expression of the ANG-GH fusion gene as compared to the addition of isoproterenol, iodoclonidine, 8-Br-cAMP or PMA alone. Furthermore, the addition of NE, 8-Br-cAMP or PMA stimulated the expression of pOGH (rANG N-806/-779/-53/+18), a fusion gene containing the putative cAMP responsive element (CRE, ANG N-806/-779) upstream of the ANG promoter (ANG N-53/+18) in OK cells, but had no effect on the expression of fusion genes containing the mutant of the CRE. Gel mobility shift assays revealed that the ANG-CRE binds with the DNA-binding domain (bZIP254-327) of the cAMP-responsive binding protein (CREB). The binding of the labeled ANG-CRE to CREB (bZIP254-327) was displaced by unlabeled ANG-CRE and the CRE of the somatostatin gene but not by the mutants of the ANG-CRE. Finally, NE stimulated the phosphorylation of CREB in OK cells. These studies demonstrate that the molecular mechanism(s) of NE action on the expression of the ANG gene in OK cells may be mediated via both the PKA and PKC signalling pathways and via the phosphorylation of CREB. The phosphorylated CREB then interacts with the CRE in the 5'-flanking region of the ANG gene and subsequently stimulates the gene expression.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

[Metabolic calculation of the growth phase in rHSA fermentation].

The model equations of the growth phase of rHSA fermentation were derived on the base of both elemental balance and metabolic balance. The unknown parameters of the model were estimated by multivariable optimization. The model can preferably describe the relations between different macroscopic reaction rates of the process and provide the key for the high-density cultivation of Pichia pastoris.

Fermentation↗
PubMed2000

1-Methyl-3-isobutylxanthine delays apoptosis induced by deprivation of growth factors in vascular endothelial cells.

AIM: To investigate the effects of 1-methyl-3-isobutylxanthine (MIBX) on apoptosis induced by deprivation of acidic fibroblast growth factor (aFGF) and serum in vascular endothelial cells (VEC). METHODS: Nuclear fragmentation was observed by fluorescence microscopy. Viability was determined by counting the cells that attached to dishes after treatments. DNA fragmentation was measured by agarose gel electrophoresis. RESULTS: The cells deprived of aFGF and serum were treated with MIBX 25-200 mumol/L for 3, 6, 9, and 12 h, respectively. Morphological changes including the formation of apoptotic bodies and DNA fragmentation of these cells were significantly suppressed by IBMX 50-200 mumol/L at 3 h and 6 h. But after 12-h treatment, no difference was observed between the treated and untreated cells. CONCLUSION: MIBX delays apoptosis of vascular endothelial cells induced by deprivation of aFGF and serum.

1-Methyl-3-isobutylxanthine↗
PubMed2000

[Experimental studies on rabbit facial nerve regeneration in chitin tubes containing nerve growth factor].

OBJECTIVE: To evaluate the nerve regeneration after implantation of chitin tubes containing nerve growth factor(NGF) in the rabbit facial nerve. METHODS: Bilateral 8 mm defect of superior buccal divisions of the facial nerves were made in 16 New Zealand rabbits. Chitin tubes containing NGF were implanted into the gaps, and autologous nerves were implanted into the right gaps as control. The nerve regeneration was evaluated with electrophysiological and ultrastructural examination after 8 and 16 weeks of operation. RESULTS: Chitin tubes containing NGF successfully induced the nerve regeneration, regularly arranged myelinated and unmyelinated axons could be observed across the 8 mm gaps, and the myelin sheath was thick with clear lamellar structure at 8 weeks after operation, The regenerated nerve fibers increased and were more mature at 16 weeks after operation. There were no significant difference in electrical impulse conduction velocity through the neural regeneration between the experimental and control sides (P > 0.05). CONCLUSION: Chitin tubes containing NGF can provide optimal conditions for regeneration of rabbit facial nerve.

Animals↗
PubMed2000

[Observation on alpha-SMA during Erigeron Breviscapus (Vant) Hand-Mazz obstructs the evolution of carcinogenesis of golden hamster cheek pouch].

OBJECTIVE: To observe dynamically that Erigeron Breviscapus (Vant) Hand-Mazz (HEr) affects the expression of alpha-smooth muscle actin (alpha-SMA). To discuss the probable mechanism of obstructing leukoplakia carcinogenesis of this medicine. METHODS: 120 golden hamsters were randomly divided into model group (48), HEr group (48) and control group (6). HEr was applied to obstruct the evolution of carcinogenesis of golden hamster cheek pouch. Immunohistochemistry was used to detect the expression level of alpha-SMA with cheek pouch specimen that besmears DMBA in 4-9 weeks. Results were compared with model group. RESULTS: Vessel density dyed with alpha-SMA continuously of HEr group was 65.76 significantly higher than that of model group 42.12 (P<0.001). High classification cases in HEr group were much more than model group when cases were divided into five groups as follow: 100%, 50%, 20%, 10%, 3% (P<0.01). CONCLUSION: HEr can raise the expression level of alpha-SMA exactly during the evolution of leukoplakia carcinogenesis of golden hamster, which shows that this medicine obstructs carcinogenesis by keeping the normal physiological function of vascular myoepithelial cell and integrity of vascular basement membrane.

English Abstract↗
PubMed2000

[Study of resisting leukoplakia canceration and angiogenesis of Herba Erigerontis].

OBJECTIVE: To evaluate the effect of resisting canceration of Herba Erigerontis HEr and that of angiogenesis; seek the mechanism of angiogenesis. METHODS: 150 golden hamsters were randomly divided into model group (66 animals), HEr group (66) and control group (18). Carcinomatous conversions of golden hamster cheek pouches induced by Sally way and interrupted by Herba Erigerontis. Ink perfusion, analysis of images, resin cast form of micro vessel, alpha-SMA detection and histopathological examination were applied to observe their changing patterns. RESULTS: The rate of leukoplakia canceration of Herba Erigerontis group was 50% lower than that of model group. The rate of normal cells was about four times more than that of model. alpha-SMA of Herba Erigerontis 65.76 was higher than that of model (P<0.001). There was no significant difference between angeion vessel area and density (P>0.05). Nevertheless, the resin cast form of micro-vessel showed that its configuration and spacious arrangement was similar to control group. CONCLUSION: Herba Erigerontis has the function of preventing leukoplakia canceration absolutely. Maybe its mechanism is to upregulate the expression of alpha-SMA. It has no obvious effect of angio-hyperplasia and expansion in the course of leukoplakia canceration. However, it has the protecting function to angio-configuration and spacious arrangement and the integrity of angeion vessed wall. Probably its mechanism is promoting blood circulation by removing blood stasis and benign angiogenesis so as to resist canceration.

English Abstract↗
PubMed1999

Regulation of human hsp90alpha gene expression.

Mammalian HSP90alpha and HSP90beta are encoded by two individual genes. On the basis of the upstream sequences of the human hsp90alpha gene, GenBank accession number U25822, we have constructed CAT reporter plasmids driven by individual fragments of the hsp90alpha gene. We found that (1) the proximal heat shock element complex located at -96/-60 enhances hsp90alpha promoter expression; (2) heat shock induction depends upon the coexistence of distal heat shock element at -1031/-1022 and the proximal heat shock element complex of the hsp90alpha gene; (3) unlike hsp90beta, downstream sequences of the transcription start site inhibit hsp90alpha expression. We conclude that the regulatory mechanisms for the expression of hsp90alpha and hsp90beta genes are different.

Binding, Competitive↗
PubMed1999

Human dendritic cells express the thrombopoietin receptor, c-Mpl.

Human thrombopoietin (TPO) is a haemopoietic growth factor that is essential for the growth and development of megakaryocytes. However, c-Mpl, the TPO receptor, has been detected in human leukaemic cell lines with a myelomonocytic phenotype. These results raise the possibility that dendritic cells (DC), a putative myeloid lineage cell, may also express c-Mpl and respond to TPO. In haemopoietic stem cell transplantation, DC could induce graft-versus-host disease by its strong antigen-presenting capacity. In this study we have examined the effect of TPO on differentiation and the antigen-presenting capacity of DC. To differentiate DC, cord blood CD34+ cells were cultured in the presence of a cytokine cocktail either in serum-free medium or RPMI1640 containing 10% fetal bovine serum. Flow cytometric analysis and immunocytochemical staining demonstrated that c-Mpl was expressed on DC. Furthermore, the expression of c-Mpl mRNA was detected in DC by RNase protection assay. However, when TPO was added to the culture system there were no significant changes in the differentiation and mixed leucocyte-stimulating capacity of DC. These findings suggest that TPO may be administered following cord blood transplantation without significant augmentation of antigen presentation mediated by DC.

Cell Division↗
PubMed1999

Molecular mechanisms of glucose action on angiotensinogen gene expression in rat proximal tubular cells.

BACKGROUND: Clinical studies have shown that the angiotensin-converting enzyme (ACE) inhibitors or angiotensin II (Ang II) receptor antagonists decrease proteinuria and slow the progression of nephropathy in diabetes, indicating that Ang II plays an important role in the development of nephropathy. We have previously reported that high levels of glucose stimulate the expression of rat angiotensinogen (ANG) gene in opossum kidney (OK) proximal tubular cells. We hypothesized that the stimulatory effect of D(+)-glucose on the expression of the ANG gene in kidney proximal tubular cells is mediated via de novo synthesis of diacylglycerol (DAG) and the protein kinase C (PKC) signal transduction pathway. METHODS: Immortalized rat proximal tubular cells (IRPTCs) were cultured in monolayer. The stimulatory effect of glucose on the activation of polyol pathway and PKC signal transduction pathway in IRPTCs was determined. The immunoreactive rat ANG (IR-rANG) in the culture medium and the cellular ANG mRNA were measured with a specific radioimmunoassay and a reverse transcription-polymerase chain reaction assay, respectively. RESULTS: D(+)-glucose (25 mM) markedly increased the intracellular levels of sorbitol, fructose, DAG, and PKC activity as well as the expression of IR-rANG and ANG mRNA in IRPTCs. These stimulatory effects of D(+)-glucose (25 mM) were blocked by an inhibitor of aldose reductase, Tolrestat. PKC inhibitors also inhibited the stimulatory effect of D(+)-glucose (25 mM) on the expression of the IR-rANG in IRPTCs. The addition of phorbol 12-myristate 13-acetate further enhanced the stimulatory effect of D(+)-glucose (25 mM) on the expression of the IR-rANG in IRPTCs and blocked the inhibitory effect of Tolrestat. CONCLUSION: These studies suggest that the stimulatory effect of a high level of D(+)-glucose (25 mM) on the expression of the ANG gene in IRPTCs is mediated, at least in part, via the de novo synthesis of DAG, an activator of PKC signal transduction pathway.

Aldehyde Reductase↗
PubMed1999

Molecular mechanism(s) of action of isoproterenol on the expression of the angiotensinogen gene in opossum kidney proximal tubular cells.

BACKGROUND: beta-adrenoceptors are present in the renal proximal tubules. We have previously reported that isoproterenol stimulates the accumulation of intracellular cAMP and the expression of the angiotensinogen (ANG) gene in opossum kidney (OK) proximal tubular cells via the beta 1-adrenoceptor. We hypothesized that the molecular mechanism(s) of action of isoproterenol on the expression of the ANG gene is mediated via the interaction of the phosphorylated cAMP-responsive element binding protein (CREB) and the cAMP-responsive element (CRE; that is, ANG N-806/-779) in the 5'-flanking region of the rat ANG gene. METHODS: The fusion genes containing the putative ANG-CRE of the rat ANG gene inserted upstream of the rat ANG basal promoter (ANG N-53/+18) fused to a human growth hormone (hGH) gene as reporter were stably cotransfected, with or without the plasmid containing the cDNA for 43 kDa CREB, into the OK cells. The effect of various agonists and antagonists of adrenoceptors on the expression of the fusion genes was evaluated by the amount of immunoreactive hGH secreted into the culture medium. The interactions of OK cellular nuclear protein(s) with the ANG N-806/779 were determined by gel mobility shift assays and by Southwestern and Western blot analysis. RESULTS: The addition of isoproterenol, forskolin, or 8-Bromo-cAMP (8-Br-cAMP) stimulated the expression of pOGH (ANG N-806/-779/-53/+18) by 135, 150, and 160%, respectively, but not mutants of the ANG N-806/-779. The stimulatory effect of isoproterenol was blocked in the presence of propranolol, Rp-cAMP, and atenolol, but not by the presence of stauro-sporine, U73122, and ICI 118,551. Transient transfection of the plasmid containing the cDNA for the catalytic subunit of protein kinase A further enhanced the stimulatory effect of 43 kDa CREB on the expression of the fusion gene. The gel mobility shift assays revealed the the nuclear protein(s) of OK cells binds to the radioactive-labeled ANG N-806/-779. The binding of the labeled ANG N-806/-779 to the OK cell nuclear protein(s) was displaced by unlabeled ANG N-806/-779, but not by the CRE of the somatostatin gene, the CRE of the tyrosine amino-transferase gene, or the mutants of the ANG N-806/-779. Southwestern blot analysis revealed that the labeled ANG N-806/-779 binds to two nuclear species of 43 and 35 kDa proteins. Western blot analysis, however, revealed that rabbit polyclonal antibodies against the 43 kDa CREB interacted with only the 43 kDa molecular species but not with the 35 kDa species. CONCLUSION: These studies demonstrate that the stimulatory effect of isoproterenol on the expression of the ANG gene may be mediated, at least in part, via the interaction of the phosphorylated CREB and the CRE in the 5'-flanking region of the rat ANG gene. The novel 35 kDa nuclear protein that is immunologically different from the 43 kDa CREB may also play a role in the expression of the ANG gene.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

A study of phlebotomine sandflies (Diptera: Psychodidae) in Yunnan Province, China. Sergentomyia (Sergentomyia) wangi n. sp.

Among the phlebotomine sandflies collected in a lime-stone cave of 21 degrees 42' N, 10 degrees 23' E and 700 m above sea level on 14th August, Mengyuan, Mengla County, Xishuangbanna District, Yunnan Province, two males of the group fallax of subgenus Sergentomyia are quite different in morphology with those hitherto recorded in the literature. In the present paper its morphology is described with seven figures and the name Sergentomyia wangi is proposed in honor of professor Chao-Tsun Wang for his contribution in study and control of leishmaniasis in China.

Animals↗
PubMed1999

Insulin inhibits angiotensinogen gene expression via the mitogen-activated protein kinase pathway in rat kidney proximal tubular cells.

The present study aimed to investigate the molecular mechanism(s) of insulin action on angiotensinogen (ANG) secretion and gene expression in kidney proximal tubular cells exposed to high levels of glucose. Immortalized rat proximal tubular cells (IRPTC) were cultured in monolayer. The levels of rat ANG and ANG messenger RNA in the IRPTC were quantified by a specific RIA for rat ANG (RIA-rANG) and by an RT-PCR assay. Insulin inhibited the stimulatory effect of a high level of glucose (25 mM) and phorbol 12-myristate 13-acetate, an activator of protein kinase C) on the secretion of ANG and the expression of the ANG messenger RNA in IRPTC. This inhibitory action of insulin on the ANG secretion and gene expression was blocked by PD98059 (an inhibitor of mitogen-activated protein kinase kinase) but not by Wortmannin (an inhibitor of phosphatidylinositol-3-kinase). PD98059 was effective in inhibiting the phosphorylation of MEK 1/2 and p44/42 MAP kinase in IRPTC stimulated by insulin. These studies demonstrate that insulin prevents the stimulatory effect of high levels of glucose on the expression of the renal ANG gene in IRPTC, at least in part, via the MAPK kinase signal transduction pathway, subsequently inhibiting the activation of the local renal renin-angiotensin system.

Androstadienes↗
PubMed1999

[Experimental study on osteoinduction of coral composited artificial bone].

OBJECTIVE: To improve the osteoinduction of coral and provide a perfect bone graft substitute for clinical bone defects. METHODS: By combining coral with collagen and recombinant human bone morphogenetic protein-2(rhBMP-2), coral/collagen/rhBMP-2 composite was obtained. The composite was implanted into the back muscle pouches of mice, and coral/collagen or coral/rhBMP-2 were implanted as control. The osteoinduction of the composite was assessed by histology and image analysis system. RESULTS: The chondrocyte differentiation and matrix formation were observed in local sites after one week, lamellar bone with bone marrow were formed after 4 weeks, and coral were absorbed partially. The quantity of osteoinduction was time-related and rhBMP-2 dose-related(P < 0.01). Coral/collagen and coral/rhBMP-2 implants did not show any bone or cartilage formation. CONCLUSION: The coral/collagen/rhBMP-2 composite possesses a superior osteoinduction and will be a new type of bone substitute to be used in orthopedic and maxillofacial surgery.

Animals↗