Search PubMed⌕ Search

Biomedical subjects

Z Dong

Publications and source records attributed to Z Dong.

At least 73 records · Page 4Linked to original sources
PubMed2001

Expression of cathepsins B, D and L in mouse corneas infected with Pseudomonas aeruginosa.

C57BL/6J naïve and immunized mice were intracorneally infected with Pseudomonas aeruginosa. Semi-quantitative RT-PCR was performed to detect cathepsin gene expression and the results were further confirmed by immunoblot analysis. The enzymatic activities of cathepsins B, D and L were measured by peptidase assays. Immunohistochemical staining was carried out to localize the expression of the cathepsins. Cathepsins B, D and L were detected in the normal cornea by RT-PCR. A peptidase assay revealed activities of all three cathepsins under normal physiological conditions. In naïve mice, enzymatic activities of cathepsins B, D and L were all significantly enhanced when the corneas were infected with P. aeruginosa and the peak of the induction appeared around day 6 postinfection. Immunoblot analysis showed increased expression of cathepsins B, D and L. The infected corneal samples from immunized mice exhibited much lower induction of enzymatic activities compared to those from naïve mice. Immunohistochemistry showed that the expression of cathepsins in the normal cornea was restricted to the epithelial tissue while the induced expression of cathepsins was predominantly in the substantia propria. Our data revealed up-regulated enzymatic activities of cathepsins B, D and L in the naïve corneas infected with P. aeruginosa, which correlated well with the inflammatory response. Immunization of mice against P. aeruginosa attenuated the inducing effect on cathepsin expression caused by infection. The time sequence for induction of cathepsin proteins and enzymatic activities suggests a mechanism of host proteolytic degradation of the extracellular matrix resulting in corneal destruction after P. aeruginosa infection.

Animals↗
PubMed2001

Induction of EGFR-dependent and EGFR-independent signaling pathways by ultraviolet A irradiation.

Most of the signal pathways involved in ultraviolet (UV)-induced skin carcinogenesis are thought to originate at plasma membrane receptors. However, UVA-induced signal transduction to downstream ribosomal protein S6 kinases, p70(S6K) and p90(RSK), is not well understood. In this report, we show that UVA stimulation of the epidermal growth factor receptor (EGFR) may lead to activation of p70(S6K)/p90(RSK) through phosphatidyl isositol (PI)-3 kinase and extracellular receptor-activated kinases (ERKs). Evidence is provided that phosphorylation and activation of p70(S6K)/p90(RSK) induced by UVA were prevented in Egfr(-/-) cells and were also markedly inhibited by the EGFR-specific tyrosine kinase inhibitors AG1478 and PD153035. Furthermore, EGFR tyrosine kinase inhibitors and EGFR deficiency significantly suppressed activation of PI-3 kinase and ERKs in regulating activation of p90(RSK)/p70(S6K) but had no effect on activation of c-Jun NH(2)-terminal kinases (JNKs) and p38 kinase in response to UVA. Thus, our results suggest that UVA-induced EGFR signaling may be required for activation of p90(RSK)/p70(S6K), PI-3 kinase, and ERKs but not JNKs or p38 kinase.

Animals↗
PubMed2001

Saccharomyces cerevisiae rad51 mutants are defective in DNA damage-associated sister chromatid exchanges but exhibit increased rates of homology-directed translocations.

Saccharomyces cerevisiae Rad51 is structurally similar to Escherichia coli RecA. We investigated the role of S. cerevisiae RAD51 in DNA damage-associated unequal sister chromatid exchanges (SCEs), translocations, and inversions. The frequency of these rearrangements was measured by monitoring mitotic recombination between two his3 fragments, his3-Delta5' and his3-Delta3'::HOcs, when positioned on different chromosomes or in tandem and oriented in direct or inverted orientation. Recombination was measured after cells were exposed to chemical agents and radiation and after HO endonuclease digestion at his3-Delta3'::HOcs. Wild-type and rad51 mutant strains showed no difference in the rate of spontaneous SCEs; however, the rate of spontaneous inversions was decreased threefold in the rad51 mutant. The rad51 null mutant was defective in DNA damage-associated SCE when cells were exposed to either radiation or chemical DNA-damaging agents or when HO endonuclease-induced double-strand breaks (DSBs) were directly targeted at his3-Delta3'::HOcs. The defect in DNA damage-associated SCEs in rad51 mutants correlated with an eightfold higher spontaneous level of directed translocations in diploid strains and with a higher level of radiation-associated translocations. We suggest that S. cerevisiae RAD51 facilitates genomic stability by reducing nonreciprocal translocations generated by RAD51-independent break-induced replication (BIR) mechanisms.

Chromosome Deletion↗
PubMed2001

Expression of oestrogen and progesterone receptors by mast cells alone, but not lymphocytes, macrophages or other immune cells in human upper airways.

BACKGROUND: Nasal polyposis often coexists with asthma in airway inflammatory conditions characterised by the infiltration of a range of immune cells. A potentially important role for ovarian hormones has been implicated in airway inflammation but the cellular target for such action is not known. METHODS: Expression of oestrogen receptors (ER) and progesterone receptors (PR) was examined using immunohistochemistry in formalin fixed nasal polyp tissues from 47 subjects. The cells positive for ER or PR were confirmed by spatial location, dual immunolabelling, and histochemical staining. RESULTS: Consistent with the known features of nasal polyps, CD4+ (T helper/inducer), CD8+ (cytotoxic/suppressor), CD68+ (macrophages), mast cells, eosinophils and neutrophils were all clearly detected by their relevant monoclonal antibodies or appropriate histochemical staining, but only mast cells tested positive for ER/PR labelling with their polyclonal and monoclonal antibodies. The frequencies for expression were 61.7% for ER positive and 59.6% for PR positive cells. The expression of ER/PR was independent of patient sex and age but was highly correlated with the numbers of mast cells (r = 0.973, p<0.001 for ER; r = 0.955, p<0.001 for PR). Fewer than 5% of mast cells were found to be negative for ER/PR expression. CONCLUSIONS: Mast cells alone, but not lymphocytes, macrophages, or other immune cells, express ER/PR in human upper airways. Numerous ER/PR positive mast cells exist in nasal polyps, indicating that this may be a major route for the involvement of sex hormones in airway inflammation when exposed to the higher and varying concentration of oestrogen and progesterone characteristic of females.

Adolescent↗
PubMed2001

Organ-specific distribution of AP-1 in AP-1 luciferase transgenic mice during the maturation process.

Activator protein-1 (AP-1), a dimeric complex consisting of proteins encoded by the jun and fos gene families, is a transcription factor induced by a variety of signals including those eliciting proliferation, differentiation, and neoplastic transformation. Although AP-1 has been widely studied in the last decade, physiological levels of AP-1 in different tissues are unclear. In the present study, we analyzed AP-1 activity in several organs (liver, kidney, brain, lung, spleen, heart, skin) of AP-1-luciferase transgenic mice of various ages. Results of these studies indicate that the level of AP-1 in young mice is much higher than that in older mice, and, second, that the skin contains considerably higher levels of AP-1 than other organs. The level of phosphorylated extracellular signal-regulated protein kinase (ERK) in skin was higher in 1- and 2-day-old mice than in mice of other ages. In addition, phosphorylated p38 kinase was high in 2-day-old and 1-wk-old mice, but phosphorylated c-Jun NH(2)-terminal kinase was not detected at any age. AP-1 activity and level of phosphorylated ERKs declined with maturation. These results imply that AP-1 activity mediated through an ERKs-dependent pathway may be involved in skin development.

Aging↗
PubMed2001

Plasminogen Activators and Inhibitors in the Corneas of Mice Infected with Pseudomonas aeruginosa.

PURPOSE: To characterize the presence of plasminogen activators and their inhibitors in the corneas during the inflammatory response in naïve and immunized mice intracorneally infected with Pseudomonas aeruginosa. METHODS: RT-PCR was used to detect gene expression for plasminogen activators and their inhibitors in naïve and immunized mice. Immunoblot analysis, zymography, and ELISA were used to demonstrate the syntheses of these proteins. RESULTS: Naïve mice intracorneally infected with P. aeruginosa showed a temporally enhanced expression of tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitors 1 and 2 (PAI-1 and PAI-2), over a several-day holding period. Immunized mice demonstrated a lower and shorter expression of these factors over the same period. Expression of these factors at the mRNA and protein levels may have been due to enzymes and inhibitors present in inflammatory cells and in resident corneal cells. CONCLUSIONS: These results show a correlation between the overexpression of the PA system in infected naïve mice as part of the inflammatory response, with eventual ocular destruction. Immunized mice exhibit a more balanced and shorter expression of the PA system, which may contribute to the restoration of corneal clarity.

Animals↗
PubMed2001

[Pests on zingiberaceous plants and their control in south China].

The pests on the zingiberaceous plants and their occurrence and damage as well as control have been investigated in the ginger plantation of South China Botanical Garden recently. 12 insect pests and 1 mite pest are common. To control them effectively, such as selecting loose, fertile soil as planting field with proper shade, applying healthy and vigorous seeds, seedling and rhizomes for propagation, regulating plant density, sanitizing the field in time are mostly recommended. The application of chemical and biological pesticides and the protection on the beneficial organisms are also stressed.

China↗
PubMed2001

Phosphatidylcholine-specific phospholipase C regulates activation of RAW264.7 macrophage-like cells by lipopeptide JBT3002.

Phospholipase activities are thought to be involved in the activation of macrophages by lipopolysaccharide (LPS). Because our previous studies showed that the synthetic lipopeptide JBT3002 might activate macrophages via signaling pathways similar to those used by LPS, we investigated whether phospholipase activities are required for activation of macrophages by JBT3002. Treatment of RAW264.7 murine macrophage-like cells with JBT3002 stimulated expression of both inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) in a dose-dependent manner. The JBT3002-induced production of nitric oxide and TNF-alpha was significantly inhibited by tricyclodecan-9-yl xanthogenate (D609), a selective inhibitor of phosphatidylcholine (PC)-specific phospholipase C (PC-PLC). JBT3002-induced expression of steady-state mRNA for both iNOS and TNF-alpha was inhibited by D609. Cells treated with JBT3002 had greater production of diacylglycerol (DAG) in 2 min, which lasted for at least 30 min and could be blocked by D609. Activation of RAW264.7 cells was not affected by butanol, a PC-specific phospholipase D inhibitor, and treatment with JBT3002 did not affect phosphatidic acid formation. RAW264.7 cells treated with DAG analogue 1-oleoyl-2-acetyl-sn-glycerol, in the presence of interferon-gamma, produced TNF-alpha. These results suggested that activation of RAW264.7 cells by JBT3002 requires PC-PLC activity.

1-Butanol↗
PubMed2001

Expression of membrane-type matrix metalloproteinases 4, 5, and 6 in mouse corneas infected with P. aeruginosa.

PURPOSE: To investigate the expression and regulation of membrane-type matrix metalloproteinases (MT-MMPs) 4, 5, and 6 in the mouse corneas infected with Pseudomonas aeruginosa. METHODS: C57BL/6J mice were intracorneally infected with P. aeruginosa. The expression of MT4-, MT5-, and MT6-MMP was detected at both the mRNA and protein levels by RT-PCR and immunoblot analysis. Immunohistochemical staining was performed to localize the expression of MT4- and MT5-MMP in the mouse corneas. RESULTS: Expression of MT4- and MT5-MMP was detected in the normal (uninfected) cornea by RT-PCR and immunoblot analysis. When infected with P. aeruginosa, the corneas showed significant induction of each MT-MMP. Localization of MT4- and MT5-MMP revealed that the expression of MT5-MMP was restricted to the epithelial tissue in the normal cornea, whereas the induced expression of MT4- and MT5-MMP was predominantly in the substantia propria, which contained most of the infiltrating cells. MT6-MMP expression was not detected in the uninfected cornea but was upregulated in the infected corneas. CONCLUSIONS: Expression of MT4-, MT5-, and MT6-MMP was induced in corneas infected with P. aeruginosa. Immunohistochemistry showed predominant immunoreactivity of MT4- and MT5-MMP in the substantia propria. Previous histologic studies have revealed different patterns of inflammatory cell infiltration with an increased number of polymorphonuclear neutrophils (PMNs) during the early stage of inflammation and increased macrophages during the late stage. These results indicate a good correlation between the overexpression of the MT-MMPs in the infected corneas and the inflammatory response-that is, leukocyte infiltration-indicating that inflammatory cells such as macrophages and PMNs may play a role in the upregulation of MT-MMPs during corneal infection, which in turn can cause the destruction of corneal tissue.

Animals↗
PubMed2001

Sodium channels in the apical membrane of human nasal epithelial cells.

OBJECTIVE: To study the electrophysiological properties of sodium channels in the apical membrane of human nasal epithelial cells. METHOD: Nasal epithelial cells of human inferior turbinate from patients with obstructive sleep apnea syndrome were cultured in serum free medium on collagen gel-coated membranes at an air-liquid interface and studied by a patch clamp technique. RESULTS: In cell-attached patches, a typical single channel current with a conductance of 21.09 pS and reversal potential of -50.96 were recorded. The permeability ratio PNa/PK was more than 5.80. In the presence of 10(-4) mmol/L amiloride in the pipette, the incidence of sodium channels decreased from 26.67% to 5.13%. This revealed that a population of channels were inhibited by amiloride at a dose of 10(-4) mmol/L. Ca2+ at dose of 10(-3) mmol/L did not influence the incidence of sodium channels. There was no obvious association between voltage and the open probability of the channels. CONCLUSIONS: Our results indicate that most Na+ channels in cell-attached patches of human nasal epithelial cells are amiloride-sensitive and Na+ selective. Only a few channels are amiloride-insensitive. The channels were not activated by extracellular Ca2+ and the open probability followed a voltage-independent manner.

Amiloride↗
PubMed2001

Remote therapeutic effect of early nerve transposition in treatment of obstetrical brachial plexus palsy.

OBJECTIVE: To report a method and remote therapeutic effect of early nerve transposition in treatment of obstetrical brachial plexus palsy. METHODS: From May 1995 to August 1996, 12 patients who had no recovery of biceps 3 months after birth were treated with nerve transposition. Eight had neuroma at the upper trunk and 4 had rupture or avulsion of the upper trunk. Mallet test was used to evaluate the results. RESULTS: The follow-up of 40-52 months showed that excellent and good recovery in functions was found in 75% of the patients and the excellent rate of phrenic nerve and accessory nerve transposition was 83.3% and 6 6.7% respectively. A complete recovery in shoulder and elbow joint function was in 3 patients and Mallet IV was in 6 patients. CONCLUSIONS: Satisfactory outcome can be obtained by using early nerve transposition in treating obstetrical brachial plexus.

Brachial Plexus↗
PubMed2001

Anatomic basis of vascularized ulnar nerve graft by the pedicle of the superior collateral ulnar artery.

OBJECTIVE: To investigate the anatomic basis of vascularized ulnar nerve graft by the pedicle of the superior collateral ulnar artery (SCUA). METHODS: Twenty-two fresh cadaver upper extremities injected i ntra-arterially with latex were dissected to study the extrinsic blood supply of the ulnar nerve. Other 6 fresh upper extremities were used to analyze the blood supply range of SCUA inside the ulnar nerve by microangiographic and histological methods. RESULTS: The ulnar nerve was supplied by a branch of the lateral thoracic artery or directly by the axillary artery in the axillary section, by b ranches of SCUA in the upper arm, and by branches from the anastomosis of the collateral arteries and the posterior branch of the recurrent ulnar artery in the elbow. SCUA could supply the whole ulnar nerve from the axilla to the wrist. CONCLUSIONS: The ulnar nerve can be used as a vascularized nerve graft by the pedicle of SCUA in treatment of brachial plexus roots avulsion by C7 transfer from healthy side.

Humans↗
PubMed2001

[Clinical and histopathologic analyses of after cataract in rabbit eyes having undergone three different cataract surgeries].

OBJECTIVE: To discuss the surgical method which can efficiently prevent the occurrence of after cataract. METHODS: Eighteen experimental rabbits were randomly divided into 3 groups. Group A was treated with phacoemulsification, group B with phacoemulsification combined with posterior continuous curvilinear capsulorhexis (PCCC) and Group C phacoemulsification combined with PCCC and anterior vitrectomy. Post-operatively, all the surgical eyes were checked with slit lamp microscope and ophthalmoscope. At the post-operative 3 months, histopathologic examinations were performed. RESULTS: There were no post-operative complications, such as retinal detachment, cystoid macular edema, etc. There were Elschnig's pearls and fibers in the peripheral area of the posterior capsule, and the amount was about the same in the 3 groups. There were Elschnig's pearls and fibers at the central area in group A. The fibrous membrane grew from the edge of the PCCC in group B. But in group C, the central area of the posterior capsule was clear, and there was no obvious pathological changes. CONCLUSION: Phacoemulsification combined with PCCC and anterior vitrectomy is a safe cataract surgical method which can effectively prevent the formation of after cataract.

Animals↗
PubMed2001

[The hEGF expression of gene--transferred human epithelium after its grafting on porcine surgical wound].

OBJECTIVE: To investigate the hEGF expression of gene -- transferred human epithelium after its grafting on porcine surgical wound. METHODS: Gene -- transferred and normal epithelia were implanted on the biological silicone membrane and then grafted on porcine surgical wound. The tissue samples were harvested from the wound and detected for the hEGF expression with immunohistochemical method on 1, 3, 5, 8 and 12 post -- grafting days. RESULTS: There existed positive hEGF expression in the wound grafted with gene -- transferred epithelia and negative hEGF expression in the wound grafted with normal epithelium. CONCLUSION: Gene -- transferred epithelium could express hEGF on the grafted wound.

Animals↗
PubMed2001

[Nasal cavity dimensions in the infants measured with acoustic rhinometry].

OBJECTIVE: To investigate the range of normal value of minimal cross-sectional area (MCA) of the nasal cavity, distance of minimal cross-sectional area from the nostril (DCA), total nasal cavity volume(NV) and total nasopharyngeal cavity volume (NPV) of healthy infants. METHOD: One hundred and seventy-five healthy infants and one hundred and eight infants suffered from acute upper respiratory tract infection were measured with acoustic rhinometry. RESULT: The range of total MCA of healthy infants was 0.2-0.5 (cm)2, DCA was 1.93-2.47 cm, NV was 2.69-4.75 cm3 and NPV was 3.83-8.92 cm3. Comparing healthy infants with infants suffered from acute upper respiratory tract infection, there all were significant differences in MCA, DCA and NV. CONCLUSION: Acoustic rhinometry suit objective assessment of the nasal airways in infants. It is demonstrated that these data can provide available information for the study of nasal physiology and pathophysiology, well as for the diagnosis and judgement of therapeutic effectiveness of nasal diseases.

Child, Preschool↗
PubMed2001

[Expression of TNF alpha and VCAM-1 in nasal polyps and relation with eosinophil infiltration].

OBJECTIVE: To study the expression of TNF alpha and VCAM-1 in nasal polyps tissue and its significance. METHOD: Paraffin sections of nasal polyps and chronic rhinitis samples were studied with immunohistochemical technique. RESULT: Expression of TNF alpha and VCAM-1 were stranger in nasal polyps tissues than in controls. There was positive relationship between the expression of TNF alpha and that of VCAM-1(r = 0.833), and expression of VCAM-1 coincide with eosinophil infiltration(r = 0.746). CONCLUSION: It is suggested that TNF alpha may up-regulate the expression of VCAM-1 in vessel endothelium, and prompt adhesion and migration of eosinophils, TNF alpha and VCAM-1 may play important role in the pathogenesis of nasal polyps.

Adult↗