Biomedical subjects

Z Wen

Publications and source records attributed to Z Wen.

At least 55 records · Page 3Linked to original sources

PubMed1999

[The effect of thrombin on tissue factor activity in cultured bovine aortic endothelial cells and its correlation with PKC pathway].

OBJECTIVE: To study the stimulating effect of thrombin on the expression of tissue factor (TF) activity in cultured bovine aortic endothelial cells (BAEC) and to elucidate if it is associated with the PKC system. METHODS: The BAECs were cultured after the Schwartz's method and one stage clotting time assay was used to measure TF activity in BAEC lysates. The TF activity was identified by EDGR-VIIa and a monoclonal antibody against TF. RESULTS: Thrombin enhanced the expression of TF activity in cultured BAEC and the effect was dose- (r = 0.78, P < 0.05, n = 8) and time-dependent (r = 0.88, P < 0.05, n = 8). PMA, a PKC activator, also induced the expression of TF activity in BAEC. H7, a protein kinase C inhibitor, inhibited the inductive effects of PMA and thrombin on TF in BAEC. CONCLUSION: Thrombin can induce the expression of TF activity in cultured BAEC and the effect depends on PKC pathway.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1999

Regulatory roles of IL-12, IL-4 and IFN-gamma on IgE synthesis in atopic patients.

OBJECTIVE: To investigate the mechanism of cytokine regulation in atopy by analyzing the effects of three major cytokines, IL-4, IL-12 and IFN-gamma on in vitro IgE synthesis of human peripheral blood mononuclear cell (PBMC) from normal individuals and atopic patients. METHODS: We investigated 5 normal individuals and 22 atopic patients including 12 allergic asthma, 8 allergic rhinitis and 2 atopic dermatitis. Human PBMCs were separated and incubated in 96-wells culture plates with different cytokines. Cultured for 7 days, the supernatant was collected and the contents of IgE synthesized in vitro were detected. RESULTS: There was no IgE synthesis in vitro of PBMC from all the normal individuals and 7 patients, however, other 15 patients' PBMC could produce IgE in vitro. We found that rhIL-4 could induce in vitro IgE synthesis of PBMC from all the normal individuals and 22 patients. rhIL-12 could inhibit IgE synthesis induced by rhIL-4. Further investigation of cytokine effects on IgE synthesis was conducted in 15 patients whose PBMCs did produce IgE in vitro (average level was 714 +/- 1105 ng/L). The following effects were observed: (1) 10 micrograms/L rhIL-4 could augment in vitro IgE synthesis from 714 +/- 1105 ng/L to higher level of 1483 +/- 1396 ng/L; (2) 20 micrograms/L rhIL-12 could inhibit in vitro IgE synthesis from 714 +/- 1105 ng/L to lower level of 452 +/- 969 ng/L; (3) rhIL-12 could block IgE synthesis induced by rhIL-4 to the level of 583 +/- 1084 ng/L; (4) 50 micrograms/L IFN-gamma could inhibit in vitro IgE synthesis from 714 +/- 1105 ng/L to the level of 461 +/- 1063 ng/L. CONCLUSIONS: rhIL-4 could induce in vitro IgE synthesis, rhIFN-gamma could inhibit the in vitro IgE synthesis and rhIL-12 could antagonize rhIL-4 effect on in vitro IgE synthesis of PBMC from atopic patients.

Adult↗

PubMed1999

[Changes in rat erythrocyte hemorheology caused by morphine dependence].

This study was aimed at the effect of morphine on the biomechanics properties of rat erythrocyte membrane in vivo and in vitro. The shear elastic modulus (E) and the surface viscotsity viscosity (micron) of rat erythrocyte membrane was measured by using the method of the new ektacytometry. The changes in hemorheology caused by morphine dependence were investigated and the mechanisms of the changes are suggested.

Animals↗

PubMed1998

Insect cytochromes P450: diversity, insecticide resistance and tolerance to plant toxins.

In the last decade, studies of individual insect P450s have blossomed. This new information has furthered our understanding of P450 diversity, insecticide resistance and tolerance to plant toxins. Insect P450s can be adult specific, larval specific or life stage independent. Similarly, insect P450s vary as to the tissues where they are expressed and in their response to inducers. Insect P450s can now be rapidly sequenced using degenerate PCR primers. Given the huge diversity represented by the Class Insecta, this technique will provide vast amounts of new information about insect P450s and the evolution of the P450 gene superfamily. CYP6D1 is responsible for monooxygenase-mediated resistance to pyrethroid insecticides in the house fly. CYP6D1 is ubiquitously expressed in adults with 10-fold higher levels found in the resistant strain compared to susceptible strains. CYP6D1 is on autosome 1 in house fly. The high level of expression found in the resistant strain is due to genes on autosomes 1 and 2. Whether or not the different CYP6D1 alleles found in resistant and susceptible strains have any role in resistance remains to be elucidated. The CYP6B gene subfamily is involved in the metabolism of host plant toxins (i.e. furanocoumarins). CYP6B gene transcripts in two Papilio (swallowtail) species have been shown to be induced by host plant toxins and in turn to metabolize these toxins. CYP6B P450s play a critical role in allowing Papilio to adapt to furanocoumarin-containing host plants. Similarities in structural and promoter regions of the CYP6B genes suggest that they are derived from a common ancestral gene. Although the P450 monooxygenases of insects are important for the metabolism of hormones and phermones, no individual P450 has yet been shown to metabolize an endogenous compound. Advances in this area are critical because they will provide important new information about insect physiology, biochemistry and development.

Animals↗

PubMed1998

[Analysis of surface markers of long-term cultured human umbilical cord blood hemopoietic cells].

OBJECTIVE: To explore the optimal time for in vitro expansion and transplantation of umbilical cord blood hemopoietic cells. METHODS: Hemopoietic cells from human umbilical cord blood were cultured with SCF, rIL-3, rIL-6 and rIL-1 beta in a long term culture system and changes of cellular surface markers were observed. RESULTS: CD3+ and CD20+ lymphocytes increased at the 7th day, and gradually decreased to the lowest level after the 14th day. CD34 positive cells increased after the 7th day, and reached the highest level at the 14th day, then decreased gradually but maintained at a higher level than that at the 7th day. CD33 positive cells increased at the 7th day, and reached the highest level from the 14th to the 21st day, then decreased after the 28th day. CD42b positive cells began to increase at the 21st day, reached the peak at the 28th day, and still maintained higher level at the 35th day. HLA-DR positive cells increased from the 14th to the 21st day. CONCLUSION: The culture system containing the four growth factors is able to expand hemopoietic cells from human umbilical cord blood and keeps them intact. From the 14th to the 21st day, the number of hemopoietic cells reached the highest level, and is suitable for transplantation.

Antigens, CD20↗

PubMed1998

[The clinical diagnostic significance on detection of Mycoplasma pneumoniae antigen in upper respiratory tract epithelium].

OBJECTIVE: To investigate the early diagnosis of pulmonary mycoplasma pneumoniae (MP) infection by detection of MP antigen in upper respiratory tract epithelium. METHOD: A prospective study on respiratory MP infection was conducted in 110 patients with acute respiratory infection from February 1996 to November 1997 in our hospital. Upper respiratory tract epithelia were collected from gargle and MP antigen was detected by immunofluorescent assay (IFA). At the same time, serum samples were taken and immunoglobulin M (IgM) fractions of specific antibody to MP were assessed by the same method in 70 of 110 patients. Moreover, clinical features, cold agglutination test and chest X-ray were also collected for analysis. RESULT: The positive rates of MP antigens and IgM antibody were 17% and 20%, respectively, while the titer on cold agglutination test > 1:8 in only two patients. The clinical features in patients with positive MP antigen and/or IgM antibody were similar to that of pulmonary MP infection. CONCLUSION: Examination of MP antigen in upper respiratory tract epithelium collected from gargle combined with serum specific IgM antibody is a good method for the early diagnosis of pulmonary MP infection.

Adolescent↗

PubMed1998

[Factors analysis on ceramic crack of metal-ceramic restorations].

This article enumerated many possible causes of ceramic crack of metal-ceramic restorations and analysed the possible causes of ceramic crack of metal-ceramic restorations. And authors also discussed the effective ways to eliminate the improper factors to keep the good bond strength of ceramics to metal alloy and to avoid ceramic crack of metal-ceramic restorations.

Dental Restoration Failure↗

PubMed1997

Mapping of Stat3 serine phosphorylation to a single residue (727) and evidence that serine phosphorylation has no influence on DNA binding of Stat1 and Stat3.

During their polypeptide ligand-induced activation Stats (signaltransducers andactivators oftranscription) 1 and 3 acquire, in addition to an obligatory tyrosine phosphorylation, phosphorylation on serine which boosts their transactivating potential [Wen, Z., Zhong, Z. and Darnell, J. E. Jr. (1995) Cell 82, 241-250]. By examining phosphopeptide maps of wild-type and mutant protein we show here that the Stat3 serine phosphorylation, like the Stat1 serine phosphorylation, occurs on a single residue, serine 727. Neither the DNA binding of Stat1 nor Stat3 is demonstrably affected by the presence or absence of the serine phosphorylation. Thus the earlier demonstration that transcription is enhanced by the presence of the serine 727 residue likely occurs after DNA binding. These findings do not agree with earlier claims of excess serine to tyrosine phosphorylation in activated Stats 1 and 3 or to claims of more stable DNA binding of serine phosphorylated Stat dimers.

Animals↗

PubMed1997

STAT signaling is active during early mammalian development.

Cytokine activation of gene expression can be mediated through signal transducer and activator of transcription (STAT) signaling pathways resulting in expression of target genes. Because many cytokines have important regulatory roles during early development, we wanted to ascertain whether STAT signaling was also active at this time and could therefore have important roles in mediating developmental processes. We have found that Stat1 and Stat3 mRNAs are present in both maternal and extraembryonic tissues during early postimplantation stages of murine development. Furthermore, analyses of STAT activity in E4.5-E9.5 decidual swellings by electrophoretic mobility shift assay demonstrated that Stat3 protein was active during this early developmental period. The identification of activated Stat3 demonstrates that STAT signaling functions during early postimplantation development in the mouse are likely to be important during early embryogenesis.

Animals↗

PubMed1997

Glutamate dehydrogenase activity profiles for type strains of ruminal Prevotella spp.

The glutamate dehydrogenase (GDH) activities for the type strains of Prevotella ruminicola (strain 23), Prevotella brevis (strain GA33), and Prevotella bryantii (strain B(1)4) were assessed by a combination of enzyme assays and analysis of migration patterns of GDH proteins following nondenaturing polyacrylamide gel electrophoresis. Unlike results with most other prokaryotes, but similar to results with other members of the family Bacteroidaceae, NADPH-utilizing specific activity was greatest in all species following ammonia-limited growth. Similar also to previous findings with P. bryantii, the NAD(P)H-utilizing GDH activity of P. ruminicola can be attributed to a single protein. However, P. brevis produces an additional GDH protein(s) in response to growth with peptides. These results conclusively demonstrate that all type strains of the ruminal Prevotella sp. grouping possess GDH activity.

Ammonia↗

PubMed1997

Stat1 serine phosphorylation occurs independently of tyrosine phosphorylation and requires an activated Jak2 kinase.

Gamma interferon (IFN-gamma) induces both tyrosine and serine phosphorylation of Stat1. Stat1 serine phosphorylation is required for maximal transcriptional activity of Stat1. In this report, we present evidence that Stat1 tyrosine phosphorylation is not a prerequisite for Stat1 serine phosphorylation, although an active Jak2 kinase is required for both phosphorylation events. Stat1 serine phosphorylation occurs with a more delayed time course than tyrosine phosphorylation. The occurrence of serine phosphorylation without tyrosine phosphorylation suggests that serine phosphorylation takes place in the cytoplasm. Experiments performed with cells expressing either dominant-negative or constitutively active Ras protein indicated that the Ras-mitogen-activated protein kinase pathway is probably not involved in IFN-gamma-induced Stat1 serine phosphorylation. Finally, a kinase capable of correct Stat1 serine phosphorylation was detected in partially purified cytoplasmic extracts from both IFN-gamma-treated and untreated cells.

3T3 Cells↗

PubMed1997

[Determination and analysis of masticatory performance of unilateral free-end removable partial denture].

In this study, the changes of masticatory performance of 30 cases (18 males, 12 females) wearing unilateral free-end removable partial dentures were studied before wearing, 1 week, 1 month and 3 months after wearing by using the light absorption method and peanuts as test food. The results showed: 1. The masticatory performance before wearing unilateral free-end removable partial denture was predominantly lower than that of normal control group. The more teeth lost, the lower unilateral masticatory performance was observed. When the number of lost teeth was few, patients compensated and maintained their masticatory performance before swallowing. 2. The masticatory performance was gradually improved with wearing denture period increasing. 3. Factors relating to the masticatory performance were sex, the extent of alveolar bone resorption and age. Except sex, the extent of alveolar bone resorption and age factors were negative correlative with the masticatory performance; However the number of occlusal units lost, chewing habit and the kinds of denture base materials had no relation to the masticatory performance.

Adult↗

PubMed1997

Erythrocyte deformation in simulated weightless human and rabbits.

Effect and mechanism of simulated weightlessness (SWL) in humans and rabbits erythrocyte deformation were studied. Erythrocyte deformation and membrane fluidity in humans and rabbits, and erythrocyte morphology and hemorreology indices in control and HDT rabbits were measured. The results were a decrease in erythrocyte deformation and membrane fluidity in humans and rabbits during SWL, a significant increase in abnormal erythrocyte, blood viscosity, hematocrit, fibrinogen, and red blood cell aggregation index in HDT rabbits. These results show that the changes in erythrocyte shape, increase of erythrocyte internal viscosity and changes in erythrocyte visco-elasticity may be causing the decrease of erythrocyte deformation in SWL humans and rabbits.

Adolescent↗

PubMed1997

[Effect of Ganoderma japonicum (Fr.) Lloyd mixture on experimental thrombosis].

The therapeutic effect of Ganoderma japonicum(Fr.) Lloyd mixture on thrombosis and its mechanism were studied. The results showed that Ganoderma japonicum(Fr.) Lloyd mixture inhibited thrombus formation in vitro and in vivo, the thrombus weight and length formed in the rabbit common carotid artery and external jugular vein were significantly decreased in the experimental group compared with the control (P < 0.01). The results suggest that Ganoderma japonicum(Fr.) Lloyed mixture has anti-thrombotic effect, blood coagulation and platelet activation were inhibited, and the ability of vascular endothelial cells against the process of thrombosis was enhanced.

Animals↗

PubMed1997

[Effects of aprotinin on heparinized whole blood activated clotting time and whole blood prothrombin time].

When aprotinin is used during cardiopulmonary bypass, there is a prolongation of the activated clotting time (ACT), which is used to monitor heparinization. The aim of this study was to observe the effects of aprotinin and heparin on whole blood ACT and whole blood prothrombin time (BPT). The results showed that when kaolin was used as the contact activator, the intrinsic clotting system was also inhibited by aprotinin, the observed ACTs with various dose aprotinin and concomitant heparin were significantly prolonged (Q = 0.757, P < 0.01). There was a dose-dependent prolongation of BPT by heparin (r = 0.985, P < 0.01). However, the heparin-mediated prolongation of BPT was not enhanced by aprotinin. The authors conclude that aprotinin prolongs heparinized whole blood activated clotting time but was not whole blood prothrombin time.

Adult↗

PubMed1996

Transcriptionally active Stat1 is required for the antiproliferative effects of both interferon alpha and interferon gamma.

Type I (alpha, beta) and type II (gamma) interferons (IFNs) can restrict the growth of many cell types. INF-stimulated gene transcription, a key early event in IFN response, acts through the Janus kinase-signal transducers and activators of transcription pathway, in which both IFN-alpha and IFN-gamma activate the transcription factor Stat1. A cell line lacking Stat1 (U3A) was not growth-arrested by IFN-alpha or IFN-gamma, and experiments were carried out with U3A cells permanently expressing normal or various mutant forms of Stat1 protein. Only cells in which complete Stat1 activity was available (Stat1alpha) were growth-inhibited by IFN-gamma. A mutant that supports 20-30% normal transcription did not cause growth restraint. In contrast, IFN-alpha growth restraint was imposed by cells producing Stat1beta, which lacks transcriptional activation potential. This parallels earlier results showing the truncated Stat1 can function in IFN-alpha gene activation. In addition to experiments on long-term cultured cells, we also found that wild-type primary mouse embryonic fibroblasts were inhibited by IFNs, but fibroblasts from Stat1-deficient mouse embryos were not inhibited by IFNs.

Animals↗

PubMed1996

The NAD(P)H-dependent glutamate dehydrogenase activities of Prevotella ruminicola B(1)4 can be attributed to one enzyme (GdhA), and gdhA expression is regulated in response to the nitrogen source available for growth.

Prevotella ruminicola B(1)4 possesses both NADPH- and NADH-linked glutamate dehydrogenase (GDH) activities, with the greatest specific activity being measured from ammonia-limited cultures. Relative to cells grown in the presence of 1 mM ammonium chloride, the NADPH-dependent activity was decreased approximately 10-fold when peptides were provided as a nitrogen source. Nondenaturing polyacrylamide gel electrophoresis (PAGE) was used to visualize the GDH protein(s) in cell extracts of P. ruminicola. For all growth conditions tested, only one GDH protein was detectable, and its relative abundance, as well as its reactivity with either NAD(P)+ or NAD(P)H, correlated well with the specific activities measured from whole-cell assays. Consistent with the findings from enzyme assays and PAGE activity gels, Northern (RNA) blot analysis revealed that expression of a gene encoding NAD(P)H-GDH activity was greatest in ammonia-grown cultures and that GDH activity is regulated in response to nitrogen source (ammonia versus peptides), probably at the level of transcription. A gene encoding the NAD(P)H-utilizing GDH activity (gdhA) was cloned, and its nucleotide sequence was determined and shown to contain an open reading frame of 1,332 bp which would encode a polypeptide of 48.8 kDa. The deduced amino acid sequence possesses three highly conserved motifs typical of family I GDHs, but several unique amino acid substitutions within these motifs were evident. These results are discussed within the context of ruminal nitrogen metabolism and the growth efficiency of succinate- and propionate-producing anaerobic bacteria.

Amino Acid Sequence↗

PubMed1996

[The pathology of labial salivary gland in the diagnosis of Sjogren's syndrome].

To explore the sensitivity and specificity of the pathology of labial salivary gland in the diagnosis of Sjogren's syndrome (SS) and its specific pathological changes in SS, 100 labial salivary gland specimens were observed and assayed in our hospital. The results indicated that there was no significant difference in acinar atrophy, duct dilatation and lymphocytes infiltration between primary SS (1 degree SS) and secondary SS (2 degrees SS) patients. But those changes had significant difference between 1 degree SS and non-CTD patients (P < 0.01). It was also found in our study that Chisholm grade IV was achieved in 78.57% 1 degree SS specimens, 65.22% 2 degrees SS specimeus and 22.22% in non-CTD specimens, respectively. According to Chisholm standard, the sensitivity and specificity of pathology in the diagnosis of these SS patients was 78.8% and 77.1%. Our patients were still classified by using Chisholm standard. If focal lymphocytes infiltration was used as the single criterion to SS diagnosis, its specificity was not high. In the diagnosis of SS authors should consider the pathologic changes of salivary gland as well as the clinical information in order to avoid misdiagnosis.

Humans↗