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Biomedical subjects

X Zheng

Publications and source records attributed to X Zheng.

At least 271 records · Page 15Linked to original sources
PubMed1995

[Correlation of fetal umbilical artery velocity waveforms with placental pathology and biochemistry].

The ratio of peak systolic to least diastolic flow velocity (S/D) of the umbilical artery was measured in 119 pregnant women and its relation with placental pathology were studied. Results obtained indicated that S/D ratio decreased gradually with advanced gestational age and showed a negative correlation (r = -0.972 8, P < 0.01). A ratio of < 3 was defined as normal value. Patients were divided into 2 groups according to the S/D ratio and their placental histological findings were compared. The number of small arteries in the tertiary villi stem and syncytial vascular membranes were significantly less in group 2 (S/D > or = 3) than that in group 1 (S/D < 3, P < 0.01). The counts of villous syncytial knots and stroma fibrosis of villi were more significant in the placenta of group 2 as well. The mean value of molondialdehyde in placenta of group 2 was significantly higher (P < 0.01) than that of group 1, while superoxide dismutase value is to the contrary (P < 0.01). These indicated that there was a reduced circulation resistance in placenta during normal pregnancy and remained stable till term. When S/D > or = 3, it indicated that physiological and biochemical changes occurred in placenta and the outcome of pregnancy might be affected.

Blood Flow Velocity↗
PubMed1995

[Immunocomplexes in tuberculous lesions].

The immunohistochemical staining was used to detect the BCG antigen, IgG, IgM, IgA and the complement C3 in the tuberculous lesions. The results showed that the III type of allergic reaction induced by immunocomplexes (IC) was one of the pathogenesis of tuberculosis. Detection of specific IC in tuberculous lesions was helpful for pathologic diagnosis of tuberculoions.

Antigen-Antibody Complex↗
PubMed1995

[Experimental observations of the quantitative changes of proteoglycan in homogenous cartilage graft in the guinea pig].

The present work was to study the quantitative change of proteoglycan (PG) in homogenous cartilage graft in the guinea pig. Histological, histochemical and biochemical studies were undertaken at different times after grafting. The results revealed that there was a marked reducing trend of matrix PG within four weeks after grafting. Four weeks afterwards all indexes except hexuronic acid restored slowly and approached the level of the control group. By the 20th week, the activity of neutromucopolysaccharide, hexosamine, acid-mucopolysaccharide and alkaline phosphatase restored to 73.6% -93.7% of the control group (P > 0.05). The changes probably were caused by immune reaction and operative trauma. PG in the cartilage matrix forms a barrier for the chondrocytes, protecting the host's immune system from contacting and reacting with the chondrocytes of the graft. Though the core protein of PG has antigenicity, it is surrounded by acidmucopolysaccharide that has no antigenicity. We concluded that it is very important to maintain a high level of PG in order to prolong the survival of a cartilage graft.

Animals↗
PubMed1995

[Involvement of opioid peptides in corticofugal modulation of pain].

The effect of opioid peptides on corticofugal modulation of nociceptive response in thalamic ventrobasal nucleus (VB) produced by cortical sensorimotor area II (Sm II) was observed. Single unit activities of VB neurons were extracellularly recorded by glass microelectrodes. The results showed that the nociceptive responses of VB neurons were attenuated at 0-7.5 minutes after stimulating Sm II (n = 14, P < 0.05). The inhibitory effect of stimulation of Sm II was reduced after ventriculer microinjection of 20ul of naloxone (n = 9), while marked inhibition was shown at 0-2.5 minutes after stimulating Sm II in the saline control group (n = 9, P < 0.05). There was a statistical difference at 0-2.5 minutes after stimulating Sm II between the two groups (P < 0.05). These studies suggest that opioid peptides might be involved in corticofugal modulation of pain.

Animals↗
PubMed1995

[Influence of SmI lesion on acupuncture-induced analgesia in thalamic Pf neurons and effects of iontophoretic ACh on their nociceptive responses].

This study aimed to investigate the role of ACh in SmI emanating descending modulation of thalamic Pf neurons in acupuncture analgesia. Multi-micropipettes were used for both extracellularly recording responses of thalamic Pf neurons to noxious stimulation of the plantar area and drug application in rats. It was found that (1) lesion of SmI obviously attenuated the inhibitory effect of EA applied at "Zusanli" and "Huantiao" points on nociceptive responses in Pfneurons; (2) after lesion of SmI iontophoretic application of ACh markedly suppressed the nociceptive responses of Pf neurons, which was significantly different from the effect of iontophoretic NaCl (as the control) showing no influence on them; (3) the inhibition induced by iontophoretic ACh applied in the rats with lesion of SmI was similar to that produced by EA applied in those with SmI intact. It is indicated that EA can activate SmI to release ACh to exert descending modulation, in which ACh is involved in SmI originating descending regulation of Pf neruons in acupuncture analgesia.

Acetylcholine↗
PubMed1995

[Silicone oil removal in 31 cases].

Silicone oil removal was performed on 32 eyes of 31 cases after silicone oil injection for an average of 13.9 months. The reasons for the silicone oil removal are the complications such as cataract, glaucoma, emulsification of the silicone oil and so on. Complete retinal reattachment without any complications was found in 6 eyes of the 32 cases. Retinal reattachment remained in place in 24 eyes after the removal, and 24 eyes achieved postoperative visual acuities > or = 0.02. After the removal, in 7 of 8 eyes with complication, retinal detachment reoccurred. The significance and the timing of the silicone oil removal were discussed in this paper.

Cataract↗
PubMed1995

[Current malaria stratification in China].

During the past 30 years since 1958 when malaria stratification was first made, a great change in malaria situation has occurred. The original stratification can not represent the current status of malaria distribution. Therefore, it needs to be redivided so as to provide basis for future malaria control work. Taking species of mosquito vector and malaria incidence as the main indices and making reference to the natural geographical division, the current malaria endemic area in China can be divided into four regions, i.e. (1) Western region: it is mostly a natural non-endemic area, except some limited areas with sporadic cases in Xinjiang Autonomous Region; (2) Northern region: the whole north-eastern and partial northern China belong to the areas where malaria has been basically eliminated; but sporadic occurrence still exist in most part of the northern China; (3) Central region: it is mostly a hypo-endemic area, only a small part has meso-endemicity; (4) Southern region: nearly 50% has meso-endemicity and the other 50% has hypo-endemicity. The demarcation line of natural non-endemic areas and the areas where malaria has been basically eliminated has been defined.

Animals↗
PubMed1995

[The use of measuring serum soluble IL-2 receptor levels in cyclosporine-A treated lupus nephritis].

Twenty-one patients with Lupus Nephritis (LN) were treated with cyclosporine-A (CsA) for three months. Serum soluble interleukin-2 receptors (SIL-2R) were measured before and after treatment and correlated prospectively with serologic findings of LN activity. The patients had significantly higher IL-2R level before treatment (during LN flare) than after treatment (disease remission). A significant positive correlation was present between serum SIL-2R and proteinuria, and ANA as well, whereas the SIL-2R levels in LN patients were inversely correlated with serum levels of C3 and CH50. These observations suggest that serum SIL-2R level is an useful marker of disease activity in LN and may serve as a helpful adjunct in the management of this disorder.

Adult↗
PubMed1995

[Influence of microiontophoretic morphine on nociceptive responses of Pf neurons after lesion of SmI].

Neuronal responses in thalamic nucleus parafasciculus (Pf) to microiontophoretic morphine were examined in 20 wistar rats after lesion of SmI. Extracellular recordings were made with five-barreled glass microelectrodes. The results showed that the spontaneous responses of Pf neurons were not statistically changed (n = 11, P > 0.05), but their nociceptive responses were attenuated at 0-8 minutes after iontophoretic morphine (n = 11, P < 0.05). There were statistically significant differences in nociceptive responses between morphine and saline groups at 0-8 minutes after iontophoresis. The results suggest that morphine may be involved in corticofugal modulation of nociceptive responses in thalamic Pf neurons.

Animals↗
PubMed1994

Spermine potentiation of recombinant N-methyl-D-aspartate receptors is affected by subunit composition.

The present study shows that both the NR1 and NR2 subunits critically affect spermine potentiation of heteromeric recombinant N-methyl-D-aspartate receptors. NR1(011), the most prominent NR1 splice variant in rat forebrain, and NR1(100), prominent in midbrain, were expressed in Xenopus oocytes singly and in combination with NR2A, NR2B, and NR2C subunits. As for NR1(011) homomers, NR1(011)/NR2B receptors exhibited spermine potentiation by two mechanisms: by increasing glycine affinity and by increasing current through receptors with bound N-methyl-D-aspartate and glycine. NR1(011)/NR2A receptors exhibited only the increase in glycine affinity, and NR1(011)/NR2C receptors exhibited neither. As for NR1(100) homomers, NR1(100)/NR2B and NR1(100)/NR2A receptors exhibited spermine potentiation only by increasing the glycine affinity. Spermine produced no potentiation of NR1(100)/NR2C receptors. Thus, the NR2B subunit "permits" both forms of spermine potentiation, the NR2A subunit permits spermine potentiation only by increasing the glycine affinity, and th NR2C subunit permits neither form of potentiation. Spermine actions on NR1/NR2 showed little voltage dependence. These observations are of interest because the NR1 and NR2 subunits are differentially distributed and developmentally regulated. At early postnatal ages, NR2B subunit mRNA was more highly expressed than NR2A and NR2C mRNAs in hippocampus, neocortex, and caudate-putamen. These findings account for many of the observed differences among neurons in polyamine actions and suggest that these actions will vary in a cell-specific and age-related manner.

Alternative Splicing↗
PubMed1994

Effect of beta-lymphocyte- and NPC-derived EBV-LMP1 gene expression on in vitro growth and differentiation of human epithelial cells.

The effect of expression of the Epstein-Barr-virus (EBV) latent membrane protein (LMP1) derived from B-lymphocytes (B) and nasopharyngeal carcinoma (NPC) (C) on the in vitro growth and differentiation of a human keratinocyte line, Rhek-1, was analyzed in clonal growth and in in vitro differentiation assays. In contrast to the polygonal parental cells, the B-LMP1-expressing sublines were spindle-shaped while the C-LMP1-expressing cells were pleomorphic. Both B- and C-LMP1-expressing sublines showed increased proliferation as evidenced by: (1) higher colony-forming efficiency (CFE) and larger colony size at reduced serum levels; (2) an increased number of epithelial cell layers formed in the air-liquid-interface culture system and (3) increased expression of proliferative cell nuclear antigen (PCNA). At low serum concentration, the C-LMP1-expressing sublines formed larger colonies than those expressing B-LMP1. In the air-liquid-interface culture system, both B- and C-LMP1-expressing lines showed reduced epithelial differentiation resulting in reduced stratification and reduced involucrin expression similar to those of the cancer cell line, Siha. The results of the present study indicate that the expression of LMP1 in human keratinocytes is associated with morphological transformation and predisposes these cells to a more neoplastic phenotype. The structural difference between the 2 genes responsible for the functional differences and transforming ability will be pinpointed in further experiments.

Antigens, Viral↗
PubMed1994

Synergistic antiplatelet effects of a nipecotamide A-1C and low dose aspirin.

1. The effects of an antithrombotic nipecotamide, A-1, and aspirin were examined separately and in combination, on human platelet aggregation in vitro and on collagen+epinephrine-induced thromboembolic death of mice in vivo. 2. Concurrent addition of the two agents to a platelet suspension resulted in a supraadditive inhibition. Racemic A-1 and its meso diastereomer A-1C behaved similarly in this respect. The IC50 value of rac. A-1 declined from 46.25 to 18.4 microM in the presence of aspirin. 3. In vivo, concurrent administration of A-1C and aspirin produced significant potentiation of antithrombotic activity. A 2-fold reduction in the ED50 of A-1C occurred when it was coadministered with aspirin to mice; also, the toxicity reduced slightly, increasing the therapeutic index by a factor of 2.2. 4. The design and synthesis of new compounds possessing the structural features of the two molecules appears to provide superior antithrombotic agents.

Adult↗
PubMed1994

Mutagenesis rescues spermine and Zn2+ potentiation of recombinant NMDA receptors.

Alternative splicing generates distinct forms of the NMDA receptor subunit NR1. NR1 subunits with an N-terminal insert (termed N1) form receptors in Xenopus oocytes with greatly reduced potentiation by spermine and Zn2+. Oocytes expressing NR1 receptors with N1 exhibited larger NMDA currents than oocytes expressing corresponding receptors without N1. In the present study, we used mutational analysis to investigate structural features of the N1 insert that control current amplitude and spermine and Zn2+ potentiation. Neutralization of positive charges in N1 rescued spermine and Zn2+ potentiation. Positive charges in N1 did not affect spermine or Zn2+ affinity. Neutralization of positive charges in N1 diminished the responses to the level of NR1 receptors lacking N1. The positively charged N1 may increase NMDA currents by causing a conformational change similar to that produced by spermine and Zn2+ in NR1 receptors lacking N1.

Amino Acid Sequence↗
PubMed1994

Cytokines and the Th1/Th2 paradigm in transplantation.

With studies elucidating the cytokine programs associated with T-cell activation, allograft rejection and tolerance induction, the Th1/Th2 paradigm has become a unifying model to explain the observed cytokine profiles. The proof that these cytokines mediate allograft tolerance, however, is at best indirect. More recent studies highlighting the redundant and pleiotropic nature of cytokine networks suggest that the Th1/Th2 paradigm may not be sufficient to explain fully the mechanisms underlying allograft tolerance.

Animals↗
PubMed1994

Expression of Ki67 antigen, epidermal growth factor receptor and Epstein-Barr virus-encoded latent membrane protein (LMP1) in nasopharyngeal carcinoma.

The expression of Ki67 antigen, epidermal growth factor receptor (EGFR) and the Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP1) in nasopharyngeal carcinoma (NPC) was immunohistochemically determined. In cases with sufficient material western blot analysis was applied to analyse the LMP1 expression. Biopsies from 20 Chinese and 3 Swedish patients with NPC were included in the study. Our results demonstrated a nuclear Ki67 staining, a membrane EGFR staining, and a dot-like cytoplasmic and/or membrane LMP1 staining pattern in tumour cells of NPC. The proportion of Ki67-positive cells correlated with tumour stage. A strong expression of EGFR was frequently seen in patients with tumour stages III and IV and was paralleled by a higher proportion of Ki67-positive cells. The majority of the LMP1-positive cases strongly expressed EGFR and had a higher proportion of Ki67-positive cells, indicating a possible effect of EBV LMP1 on the proliferation of tumour cells in NPC. The increased expression of EGFR and Ki67 in NPC at late tumour stage indicates their possible use in malignancy grading of NPC.

Biomarkers, Tumor↗
PubMed1994

B7(+)-transfectant tubular epithelial cells induce T cell anergy, ignorance or proliferation.

We have previously established that interferon (IFN)-gamma stimulated, antigen-pulsed tubular epithelial cells (TEC) stimulate antigen (Ag) specific activation of T cell hybridomas to express IL-2. In contrast, these Ag pulsed TEC do not stimulate T helper 1 (Th1) clones to proliferate, but rather render them unresponsive, since Ag pulsed spleen cells cannot restore these cells to proliferate. The interaction of the T cell CD28 surface protein with its ligand B7 expressed on Ag presenting cells bearing Ia is a potent co-stimulatory signal capable of inducing T cell proliferation. Hence, the lack of B7 on TEC was hypothesized to be responsible for anergy in these Th1 cells. Therefore, the B7 gene was transfected into a SV40 transformed TEC or Chinese hamster ovary (CHO) cells, and created TEC and CHO cells expressing surface B7 protein. TEC-B7 (IFN-gamma stimulated, Ag pulsed) express Ia and induce IL-2 production by T cell hybridomas. In contrast, T cell proliferation was not induced by TEC-B7 or CHO-B7 cells; however, these Th1 cells were not anergic since they could be stimulated to proliferate to Ag pulsed spleen cells (immunological ignorance). However, co-cultivating TEC- B7 (IFN-gamma stimulated, Ag pulsed) with Th1 cells stimulated through the T cell receptor (TCR) using anti-CD3 monoclonal antibody (mAb) caused these Th1 cells to proliferate. Furthermore, anti-CD28 and anti-B7 mAbs blocked this response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Endothelium dependent vasomotor responses to endogenous agonists are potentiated following ACE inhibition by a bradykinin dependent mechanism.

OBJECTIVE: The aim was to investigate the effects of angiotensin converting enzyme inhibition on agonist induced endothelium dependent vasodilatation in vivo. METHODS: Chronically instrumented conscious dogs (n = 8) were prepared for the measurement of coronary blood flow, diameter of the left circumflex coronary artery, mean arterial blood pressure, and heart rate. Intracoronary infusions of acetylcholine, adenosine, and bradykinin that induced dose dependent increases in coronary blood flow and diameter were performed with and without intracoronary administration of captopril (1 mg.kg-1) and enalapril (0.4 mg.kg-1). The effects were studied of concomitant inhibition of bradykinin actions by the specific B2 kinin antagonist HOE-140 (10(-7) M), NO-synthesis by NG-nitro-L-arginine-methyl ester (L-NAME, 2 x 10(-5) M), or cyclo-oxygenase by indomethacin (10(-7) M) (all intracoronary). RESULTS: Neither captopril nor enalapril had significant vasodilating effect on the coronary vasculature when given alone. In contrast, both ACE inhibitors potentiated the agonist induced increases in coronary blood flow by bradykinin and acetylcholine (p < or = 0.01). HOE-140 strongly antagonised the effects of infused bradykinin and prevented the potentiation of acetylcholine responses by ACE inhibition. L-NAME caused hypertension and bradycardia and abolished the responses to acetylcholine and adenosine, but only partially attenuated the bradykinin induced increases in coronary blood flow. Simultaneous ACE inhibition reduced the hypertensive effect of L-NAME and partially restored the responses to bradykinin. Indomethacin reduced the responses to bradykinin but did not affect acetylcholine and adenosine induced coronary vasodilatation. The potentiation of the response to acetylcholine induced by ACE inhibition was, however, diminished by indomethacin. CONCLUSIONS: In the coronary vasculature of the dog, ACE inhibitors enhance vasomotor responses to endothelium dependent agonists by facilitating the release of both NO and PGI2, a mechanism which is coupled to endogenously formed bradykinin. ACE inhibitors may thus mediate their effects in vivo partly by increasing the capacity of the endothelium to release autacoids.

Acetylcholine↗