Biomedical subjects

Jin Zhao

Publications and source records attributed to Jin Zhao.

53 records · Page 3Linked to original sources

PubMed2004

Mechanical damage to corneal stromal cells by epithelial scraping.

OBJECTIVE: Corneal epithelial scraping, a common clinical procedure, triggers a loss of underlying keratocytes. This study was conducted to examine whether the physical impact of epithelial scrape injury plays any role in the death of these cells. METHODS: Epithelial debridement was carried out on the cornea of a freshly killed mouse either by mechanical scraping with a blunt spatula, as in the clinical scraping, or lifting by repeated touching with a gelatin-coated slide. Subsequently, nuclei, nuclear envelope, microtubules, microfilaments, and plasma membranes were examined with specific probes. Some corneas were fixed with alcohol before scrape injury. Fate of keratocytes after epithelial injury was investigated with isolated eyes ex vivo and living mice in vivo. Some of the procedures were performed with human donor corneas. RESULTS: Within seconds of, or possibly simultaneous to, mechanical epithelial scraping, nuclei of underlying keratocytes became grossly deformed to assume extremely stretched morphology, accompanied by destruction of microfilaments and microtubules as well as compromised plasma membranes. These cells deteriorated gradually over several hours both ex vivo and in vivo. Nuclear deformation was observed even when the cornea was fixed with alcohol before epithelial scraping. When the epithelium was removed by gentle lifting, nuclei remained mostly intact. Similar results were obtained with human donor corneas. CONCLUSION: Mechanical epithelial scraping can cause immediate damage to underlying anterior keratocytes by a physical impact, which appears to lead to degeneration of these cells.

Animals↗

PubMed2004

[Typing human papilloma virus (HPV) infection in the warts of oral mucosa from HIV-positive patients].

OBJECTIVE: To detect and type human papilloma virus (HPV) in the warts of oral mucosa from HIV-positive patients, and better understand the biological characters of these oral warts. METHODS: Polymerase chain reaction (PCR) was used to detect and type HPV infection by consensus HPV primers Gp5+/Gp6+ and specific HPV primers (HPV6/11, 16, 18, 31, 33) in 34 cases of oral mucosa warts from HIV-positive patients. RESULTS: The HPV infection rate was 88.2% by consensus HPV primers Gp5+/Gp6+; the HPV infection rate of HPV6/11, 16, 18, 31 was respectively 47.06%, 11.67%; 2.94%, and 5.88% by specific HPV primers. CONCLUSION: Most lesions of oral warts from HIV-positive patients are associated with the infection of HPV. The low risk HPV6/11 infection is more common than the high risk HPV16, 18, 31.

HIV Infections↗

PubMed2004

[Application of fluorescent real-time reverse transcriptase-polymerase chain reaction in detecting influenza viruses].

OBJECTIVE: To apply fluorescent real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in detecting influenza viruses. METHODS: A total of 207 oral swab samples were obtained in 16 collections from SARS patients and suspected influenza outbreak cases. They were subjected to influenza virus detection by fluorescent real-time RT-PCR, MDCK cell culture, and hemagglutinin inhibition assay. RESULTS: Out of 207 samples, 79 (38.16%) were positive for influenza viruses when tested by fluorescent real-time PCR, and 62 (29.95%) positive when tested by MDCK cell culture. There was a statistically significant difference between them (chi square=8.64, P less than 0.005). From 104 cases in 9 collections dual serum samples were obtainable. When tested with hemagglutinin inhibition assay, 64 cases (61.54%) showed a 4-fold increase against H3N2 antigen. CONCLUSION: This study showed that fluorescent real-time PCR is a reliable, sensitive, and fast method for detecting influenza viruses.

Cell Culture Techniques↗

PubMed2004

[Construction and expression of vector with aroA-in gene and its transformation in tobacco].

Inteins are intervening protein sequences that undergo self-excision from precursor protein with concomitant joining of flanking sequences. Here, we demonstrated intein cis-splicing in Nicotiana tabacum nuclear genomes by using artificial cis Ssp DnaB and Rma DnaB intein. We want to test whether protein splicing can occur in higher eucaryotic cell,which would play an important role in transgene containment in transgenic plants. Glyphosate-resistant Salmonella typhimurium aroA gene was divided at position 235/236 aa within EPSPS by inverse PCR from pLEPSPS. Amplified gene products with artificial cis-Ssp DnaB/Rma DnaB intein and split-Ssp DnaB/Rma DnaB intein were inserted at position 235 of EPSPS respectively to construct plasmid pLEBC, pLERC, pLEBT and pLERT. Above four aroA-In gene fusions were ligated into pET-32 to obtain E. coli expression vectors termed pETLEBC, pETLEBT, pETLERC and pETLERT. E. coli DE3 cells containing individual recombinant plasmids described above were induced by IPTG to produce corresponding protein products. Detectable spliced EPSPS and unspliced precursor demonstrated that splicing occurred in bacteria. aroA-cis SSp DnaB and aroA-cis Rma DnaB were ligated into Agrobacterium tumefaciens binary vector pLYM. Then A. tumefaciens containing EPSPS-(cis) intein cassettes were used for leaf disk transformation in N. tabacum. Integration of aroA-In gene into plant genome was confirmed by genomic PCR analyses. To verify the expression of fusion genes at transcriptional level, RT-PCR analyses were performed and the expected products were identified. These results suggested that plant cells support expression of S. typhimurium aroA-In fusion gene in nulear genomes. Thus,we speculated the existence of protein-splicing activity in plant cells. This opens the possibility of applying intein trans-splicing technique to reduce/prevent gene transfer by way of pollen in transgenic plants.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗

PubMed2003

Unveiling metal-cage hybrid states in a single endohedral metallofullerene.

The local structural and electronic properties of individual metallofullerenes are studied using scanning tunneling microscopy, scanning tunneling spectroscopy, and theoretical simulations. The energy-resolved metal-cage hybrid states of a single endohedral metallofullerene Dy@C82 isomer I have been spatially mapped, supporting a complex picture consisting of the orbital hybridization and charge transfer for the interaction between the cage and the metal atom. The relative position of the encapsulated Dy atom inside the cage and the molecular orientation on the surface have been inferred by comparing the experimental results with theoretical simulations. The combined technique provides promising applications in the fields of in situ characterization and diagnostics of metallofullerene-based nanodevices.

Journal Article↗

PubMed2003

DNA damage of tumor-associated lymphocytes and total antioxidant capacity in cancerous patients.

The purpose of this study was to assess DNA damage of tumor-associated lymphocytes (TALs) in malignant pleural effusion (MPE), the total antioxidant capacity (TAC) of plasma and MPE from patients with carcinoma, and DNA repair effect of melatonin. TAC of plasma was measured in 28 cancer patients with MPE and in 33 healthy persons, and also TAC of MPE supernatant was measured in these patients. DNA damages of peripheral blood mononuclear cells (PBMCs) and of TALs were assessed using comet assay. The TAC of plasma was remarkably lower in cancer patients (8.41+/-1.78 U/ml) than that in healthy persons (10.52+/-1.64 U/ml, P<0.001). The TAC of MPE supernatant (6.34+/-1.57 U/ml) was significantly lower than that of plasma in cancer patients (8.41+/-1.78 U/ml, P<0.001). The comet percentage of PBMCs was higher in cancer patients (16.8+/-7.9) than that in healthy persons (10.4+/-4.9, P<0.01). Within cancer patients, the comet percentage of TALs (41.9+/-11.7) was significantly higher than that of PBMCs (16.8+/-7.9, P<0.001). A negative correlation was observed between the TAC of MPE supernatant and the comet percentage of TALs in patients (r=-0.538, P<0.01). After treatment with melatonin, comet percentage of TALs declined significantly from 42.6+/-12.8 to 27.1+/-9.9 (P<0.001). These data show that lower TAC of MPE supernatant may be related to higher degree of DNA damage of TALs and that melatonin may facilitate the repair of the damaged DNA.

Antioxidants↗

PubMed2003

Cake consolidation in a compression-permeability cell: effect of side-wall friction.

A simulation study was made to investigate the transient state stresses, strains, and void ratio distributions in the formation of a filter cake in a compression-permeability cell (C-P cell). A finite-element software package, ABAQUS, was used for the simulation and emphasis was placed on the effect of the cake/cell-surface friction. The validity of the simulation was assessed by comparing simulation results with available experimental data.

Journal Article↗

PubMed2003

Plastic deformation in cake consolidation.

Cake filtration has a variety of applications in wastewater treatment by solid/liquid separation processes. In order to obtain the physical properties of the filter cake, a Compression-Permeability Cell (C-P Cell) can be used to examine the constitutive relationships among the solid compressive stresses, porosity and the specific filtration resistance. In this paper, a mathematical model is proposed to study the transient distribution of stresses, strains and void ratios in the confined cake of a C-P Cell under constant axial loads for dewatering. Simulations have been carried out using a plasticity model and the sensitivity analysis has revealed the possible contribution a finite plasticity can bring about the two types of cake examples with either medium or high compressibility.

Journal Article↗

PubMed2003

Lacrimal gland as the major source of mouse tear factors that are cytotoxic to corneal keratocytes.

We have previously shown that mouse tears are cytotoxic to the corneal keratocytes. Since tear components are derived from both lacrimal tissues and ocular surface epithelium, we sought to determine the source of the cytotoxic factors in the mouse tear fluid. Cytotoxicity to keratocytes was assessed by an ex vivo assay using an isolated eye; after treatment with test samples, segmentation and disappearance of stromal nuclei were determined by DAPI nuclear staining. Following biological tissues and fluids were examined either directly or after preincubation at 37 degrees C for 2-15 hr: extraorbital lacrimal gland (ELG), intraorbital lacrimal gland (ILG), Harderian gland, Meibomian gland, corneal epithelium, bulbar conjunctiva, palpebral conjunctiva, serum, aqueous humor, and lacrimal fluid collected from a secretory duct of ELG. Under the ex vivo assay conditions, ELG and ILG, with or without preincubation, exhibited a cytotoxic effect comparable to that of diluted tears. Lacrimal fluid collected from an ELG duct was similarly effective. These specimens triggered nuclear segmentation that is typical of apoptotic nuclei. All other specimens showed no effect on stromal nuclei under the identical conditions. In some animals, ELG was surgically removed and the tear cytotoxicity was examined in vivo. The tear cytotoxicity in these animals was lost after the surgery, indicating an involvement of ELG, but it was restored 4-24hr afterward, suggesting a compensatory role of ILG.These results suggest that ELG and ILG are the major sources of tear factors that are cytotoxic to the keratocytes in the mouse.

Animals↗

PubMed2003

Centripetal movement of corneal epithelial cells in the normal adult mouse.

PURPOSE: To study the natural movement of corneal epithelial cells in the normal adult mouse with histology and in vivo microscopy. METHODS: A transgenic mouse line that was engineered to ubiquitously express green fluorescent protein (GFP) was used to visualize corneal epithelial cells. For histology, epithelial GFP was imaged in a wholemounted cornea en face, and also in frozen cross-sections, under a fluorescence microscope. For in vivo studies, the anesthetized mouse was placed on a custom-made observation platform under a fluorescence microscope. Epithelial fluorescence was digitally recorded two to three times a week, and a rate of cell movement was determined from the time-lapse sequences. RESULTS: The GFP expression in the corneal epithelium was nearly ubiquitous up to about 1 week after birth, and thereafter it gradually became sporadic, resulting in a mosaic pattern of GFP positive cells, with the brightest cells present in the basal and suprabasal layer of the epithelium. Both high- and low GFP-cells formed radial streaks toward the central cornea, frequently displaying vortex patterns at the center. Clusters of several high-GFP cells were tracked in living mice for up to 7 weeks, and an analysis of time-lapse sequences revealed that they moved centripetally at an average rate of 26 micro m/d. CONCLUSIONS: Corneal epithelium of adult GFP mice exhibits a pattern of GFP expression that is suitable for studying cell movement in the normal cornea. Epithelial cells at the basal or suprabasal layers move centripetally in these mice at an average rate of 26 micro m/d.

Animals↗

PubMed2003

[Studies on protein-based identification method of genetically modified capsicum].

The detection system based on protein is a method to evaluate the safety of genetically modified foods (GMF). Using cecropin BD gene in capsicum, a detecting method was set up. It is a system of evaluating the real expressive condition and safety of the foreign target protein of GMF. In this studies, with the preformative technic method, a satisfactory results by making use of hemolymph of immunized pupae of Antheraea pernyi as standard experimental material was achieved, comparing with the realities of the goal protein expressive condition of cecropin D gene in capsicum. The detecting steps were as following: the goal protein from material was extracted roughly, then with CM-Sepharose-FF ion-exchange chromatography twice, the goal protein was purified moderately. The purified product was identified by detecting the anti-bacterial activity, electrophoresis, biological auto-photography of the goal protein and MADDI-TOF mass spectrum. The results showed that the expressive foreign target protein in transgenic capsicum was in accordance with standard protein in the physical and chemical property, anti-bacterial activity and molecular weight. It indicated that expression of the target gene in capsicum is real, it corresponded to expected value. The separation, purification and identification methods of cecropin D were established in the study. By means of the comparative experiments about anti-bacterial activity and molecular weight of anti-bacterial peptide(ABP) from GM-capsicum and hemolymph of immunized pupae of Antheraea pernyi, the identification method of target protein from GM-capsicum was set up. The method is easy to be operated, fast and feasible.

Capsicum↗

PubMed2003

Comparative study on apoptosis induction of SMMC7721 and Vero cells by Clostridium difficile toxin A.

BACKGROUND & OBJECTIVE: Clostridium difficile is recognized as a frequent cause of antibiotic-induced diarrhea. This study was designed to investigate whether Clostridium difficile toxin A might induce apoptosis on human hepatoma cell line SMMC7721 and African green monkey kidney Vero cells. METHODS: Highly purified toxin A was obtained by bovine thyroglobulin affinity purification followed by ion exchange chromatography on Q sepharose. The apoptosis induction of toxin A was examined on SMMC7721 cells with Vero cells as a control. Inhibition of proliferation was measured by MTT assay. Morphological assessment of apoptosis was performed with fluorescence and electronic microscopy. DNA fragmentation was observed by agarose gel electrophoresis. Cell cycle distribution was analyzed by flow cytometry. RESULTS: Toxin A (0.293-4.690 mg x L(-1) ) inhibited proliferation of SMMC7721 and Vero cells in a time- and concentration-dependent manner. Morphological changes of typical apoptosis showed that SMMC7721 had a higher percentage of apoptosis than Vero cells. Agarose gel electrophoresis of DNA from SMMC7721 treated with toxin A for 48 hours revealed a "ladder" pattern. CONCLUSION: Clostridium difficile toxin A induced apoptosis of SMMC7721 and Vero cells. The apoptosis induction on SMMC7721 cells was more effective than that on Vero cells.

Animals↗

PubMed2003

[Application of mass spectrometry in the proteome research].

Electrospray ionization(ESI) and matrix-assisted laser desorption ionization(MALDI) are two kinds of newly-developed mass spectrometry techniques. The application of mass spectrometry is described in the proteome research such as MS charting, determination of molecular weight, peptide mass fingerprinting(PMF) and peptide sequence validation. The advantages of mass spectrometry are sensitive, accurate, rapid, high-throughput and automated. They have been proved a powerful technique and can be used as an important method for proteome research.

Mass Spectrometry↗

PubMed2003

[Clinical studies of calcium hydroxide disinfecting infectious root canal of deciduous tooth].

OBJECTIVE: To search for a more ideal way to disinfect infectious root canal of deciduous tooth. METHODS: According to bacterial occurrence and clinical effect, 40 cases of infectious root canal of deciduous teeth disinfected with Ca(OH)2 were investigated, the other 40 cases with traditional way of using FC and CP respectively, were used as the control. RESULTS: Fist of all, the bacteria of deciduous tooth infectious root canal were same as the bacteria of permanent tooth infectious root canal. Secondly, Ca(OH)2 was stronger in disinfecting deciduous tooth infectious root canal. Thirdly, so far as sterilization was concerned, Ca(OH)2 had the same disinfectant as FC, and was better than CP, but FC had some irritation and poisonous side-effects to periodical tissue. So Ca(OH)2 was safe and effective for deciduous tooth infectious root canal. CONCLUSION: It was a more ideal way to disinfect deciduous tooth infectious root canal by Ca(OH)2.

Calcium Hydroxide↗

PubMed2003

[A study on oxidative DNA damage and lipid peroxidation in patients with tuberculous pleurisy].

OBJECTIVE: To explore the levels of mononuclear cell oxidative DNA damage and lipid peroxidation in patients with tuberculous pleurisy. METHODS: The mononuclear cell DNA damages in pleural effusion and peripheral blood of 28 patients with tuberculous pleurisy and in peripheral blood of 25 healthy persons were detected by single cell gel electrophoresis (comet%). The levels of total antioxidative capacity (TAC) in supernatant of pleural effusion and blood plasma of 28 patients and in blood plasma of 25 healthy persons were measured by o-phenanthroline colorimetric analysis. The contents of malondialdehyde (MDA) of blood plasma from 28 patients and from 25 healthy persons were measured by thiobarbituric acid colorimetric analysis. The differences between groups were analyzed by t test. RESULTS: The comet percentage of mononuclear cells in pleural effusion from patients with tuberculous pleurisy was (41.3 +/- 14.5)%, which was significantly higher than that in the peripheral blood (21.2 +/- 4.2)% (P < 0.01); The level of TAC in supernatant of pleural effusion was (5 172 +/- 1 195) U/L, which was lower than that in the blood plasma (8 656 +/- 1 592) U/L (P < 0.01). There was a negative correlation between the comet percentage of mononuclear cells and the level of TAC (r = -0.425, P < 0.05) in pleural effusion. The comet percentage of mononuclear cells in peripheral blood and the content of MDA in blood plasma from patients were (21.2 +/- 4.2)% and (8.25 +/- 1.37) micro mol/L, which were significantly higher than those from the controls (8.9 +/- 3.7)% and (4.46 +/- 0.93) micro mol/L respectively (P < 0.01); The level of TAC in blood plasma was (8 656 +/- 1 592) U/L, which was lower than that from the controls (10 610 +/- 1 399) U/L (P < 0.01). There were negative correlations between the level of TAC in blood plasma and the comet percentage of mononuclear cells in peripheral blood or the content of MDA in blood plasma (r = -0.438, -0.413, P < 0.05), and there was a positive correlation between the comet percentage of mononuclear cells in peripheral blood and the content of MDA in blood plasma (r = 0.899, P < 0.01). CONCLUSION: There is oxidation/antioxidation imbalance in patients with tuberculous pleurisy, namely oxidative stress, with inadequate total antioxidative capacity, particularly in the diseased pleural cavity.

Adult↗

PubMed2002

Cellular response to hypoxia involves signaling via Smad proteins.

The transforming growth factor-beta (TGF-beta) family of cytokines regulates vascular development and inflammatory responses. We have recently shown that exposure of human umbilical vein endothelial cells (HUVECs) to hypoxia (1% O(2)) increases gene expression and bioactivation of TGF-beta2 and induces its downstream effectors, Smad proteins (Smads), to associate with DNA. In the present study, we show that hypoxia-induced TGF-beta2 gene expression is dependent on thrombospondin-1-mediated bioactivation of latent TGF-beta. Blocking TGF-beta2 but not TGF-beta1 in hypoxic endothelial cell cultures inhibited induction of the TGF-beta2 gene, indicating that an autocrine mechanism driven by bioactivation of TGF-beta2 leads to its gene expression in hypoxic HUVECs. Exposure of HUVECs to hypoxia resulted in phosphorylation and nuclear transportation of Smad2 and Smad3 proteins as well as stimulation of transcriptional activities of Smad3 and the transcription factor hypoxia-inducible factor-1alpha and culminated in up-regulation of TGF-beta2 gene expression. Autocrine regulation of TGF-beta2 production in hypoxia may involve cross-talk between Smad3 and HIF-1alpha signaling pathways, and could be an important mechanism by which endothelial cells respond to hypoxic stress.

Biological Transport↗

PubMed2002

[Study on the identification of genomic modified foods].

Nucleotide-based amplification method is an important system for the identification of genomic modified foods (GMF). Roundup Ready Soybeans (Monsanto company), Bt 176 GM maize (Novartis/Ciba-Geigy company) and Cecropin D capsicum was used as material to search for the feasibility of investigating the safety of GMF by PCR method. Primers specific for inserted genes and crop endogenous genes in Roundup Ready Soybeans, Bt 176 maize and Cecropin D capsicum were applied. The discrimination system for GM soybeans, GM maize and GM capsicum from the counterpart of non-GM products and the detection system for correlating marker genes and transgenes are established. The method was easy and fast, and the corresponding results fixed the standard or declared data.

Capsicum↗