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Biomedical subjects

Z Zhu

Publications and source records attributed to Z Zhu.

At least 91 records · Page 5Linked to original sources
PubMed2001

Gene transfer and expression of platelet-derived growth factors modulate periodontal cellular activity.

Platelet-derived growth factor (PDGF) is a potent stimulator of wound healing. PDGF gene therapy may promote greater periodontal regeneration than local protein application, due to sustained growth factor delivery to the target tissue. This investigation tested the ability of recombinant adenoviruses (rAds) encoding PDGF-A or PDGF-1308 (a PDGF-A dominant-negative mutant that disrupts endogenous PDGF bioactivity) to affect cells derived from the periodontium. Osteoblasts, periodontal ligament fibroblasts, and gingival fibroblasts were transduced with rAds, and gene expression, DNA synthesis, and cell proliferation were evaluated. The results revealed strong message for the PDGF-A gene for 7 days following gene delivery. Ad2/PDGF-A enhanced the mitogenic and proliferative response in all cell types, while Ad2/PDGF-1308 potently inhibited mitogenesis and proliferation. In conclusion, Ad2/PDGF can effectively transduce cells derived from the periodontium and promote biological activity equivalent to PDGF-AA. These studies support the potential use of gene therapy for sustained PDGF release in periodontal tissues.

Adenoviridae↗
PubMed2001

Comparative analysis of galectins in primary tumors and tumor metastasis in human pancreatic cancer.

Galectins are galactoside-binding proteins that exhibit an important function in tumor progression by promoting cancer cell invasion and metastasis formation. Using Northern blotting and Western blotting analysis, in situ hybridization (ISH), and immunohistochemistry (IHC), we studied galectin-1 and galectin-3 in tissue samples of 33 primary pancreatic cancers and in tumor metastases in comparison to 28 normal pancreases. Furthermore, the molecular findings were correlated with the clinical and histopathological parameters of the patients. Northern blotting and Western blotting analysis showed significantly higher galectin-1 and galectin-3 mRNA and protein levels in pancreatic cancer samples than in normal controls. For galectin-1, no ISH signals and immunoreactivity were observed in acinar or ductal cells in the normal pancreas and in pancreatic cancer cells, whereas fibroblasts and extracellular matrix cells around the cancer mass exhibited strong mRNA signals and immunoreactivity. Galectin-3 mRNA signals and immunoreactivity were strongly present in most pancreatic cancer cells, whereas in the normal controls only faint ISH and IHC signals were seen in some ductal cells. Metastatic pancreatic cancer cells exhibited moderate to strong galectin-3 immunoreactivity but were negative for galectin-1. No relationship between the galectin-1 and galectin-3 mRNA levels and the tumor stage or between the IHC staining score and the tumor stage was found. However, galectin-1 mRNA levels and the IHC staining score were significantly higher in poorly differentiated tumors compared with well/moderately differentiated tumors, whereas for galectin 3 no differences were found. The expression pattern of galectin-1 and galectin-3 in pancreatic cancer tissues indicates that galectin-1 plays a role in the desmoplastic reaction that occurrs around pancreatic cancer cells, whereas galectin-3 appears to be involved in cancer cell proliferation. High levels of galectin-3 in metastatic cancer cells suggest an impact on metastasis formation.

Adenocarcinoma↗
PubMed2001

Platelet-derived growth factor (PDGF) gene delivery for application in periodontal tissue engineering.

BACKGROUND: A challenge in the reconstruction of periodontal structures is the targeted delivery of growth-promoting molecules to the tooth root surface. Polypeptide growth factors such as platelet-derived growth factor (PDGF) stimulate both cementogenesis and osteogenesis. Recent advances in gene therapy offer the advantage of delivering recombinant proteins to tissues for extended periods of time in vivo. METHODS: Recombinant adenoviral vectors encoding for the PDGF-A gene were constructed to allow delivery of PDGF transgenes to cells. The recombinant adenoviruses were assembled using the viral backbone of Ad2/CMV/EGFP and replacing GFP (reporter gene encoding green fluorescent protein driven by the cytomegalovirus promoter [CMV] within adenovirus type 2) with the PDGF-A gene. Root lining cells (cloned cementoblasts) were transduced with Ad2/PDGF-A and evaluated for gene expression, DNA synthesis, and cell proliferation. PDGF-inducible genes, c-myc and osteopontin, were also evaluated following gene delivery of Ad2/PDGF-A. RESULTS: The results revealed high level transduction of cementoblasts by gene transfer for 7 days as evidenced by flow cytometry and Northern blotting. Cementoblast DNA synthesis and subsequent proliferation were stimulated by Ad2/PDGF-A at levels equal to or greater than continuous rhPDGF-AA application. Strong message for the PDGF-A gene and protein as evidenced by Northern blotting and immunocytochemistry was noted. Furthermore, the potent induction of c-myc and osteopontin mRNA was found after PDGF gene delivery to cementoblasts. CONCLUSIONS: These findings demonstrate that gene delivery of platelet-derived growth factor stimulates cementoblast activity that is sustained above that of rhPDGF-AA application. The use of gene therapy as a mode of growth factor delivery offers a novel approach to periodontal tissue engineering.

Adenoviridae↗
PubMed2001

Determination of nucleic acids using calcein-neodymium complex as a fluorescence probe.

A novel fluorometric method has been developed for rapid determination of DNA and RNA with calcein-neodymium complex as a fluorescence probe. The method is based on the fluorescence enhancement of calcein-Nd(III) complex in the presence of DNA or RNA, with maximum excitation and emission wavelength at 489 nm and 514 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.5 - 3.0 microg/ml for both DNA and yeast RNA, 0.4 - 2.0 microg/ml for fish sperm DNA (FS DNA) and 0 - 3.0 microg/ml for calf thymus DNA (CT DNA). The corresponding detection limits are 15.1 ng/ml for DNA, 21.2 ng/ml for yeast RNA, 10.5 ng/ml for FS DNA and 8.9 ng/ml for CT DNA. The interaction mechanism for the binding of calcein-Nd(III) complex to DNA is also studied. The results of absorption spectra, fluorescence polarization measurements and thermal denaturation experiments, suggested that the interaction between calcein-Nd(III) complex and DNA is an electrostatic interaction.

Animals↗
PubMed2001

[Morphological and histological studies on Aralia plants].

OBJECTIVE: To make clear the descriptions and microscopic histological structures of the roots, stems and rootstocks for twelve species from Aralia plants. METHODS: Observing the descriptions and histological characteristics. RESULT: The histological characteristics of the various species are basically identical. Each of them equally contains cluster crystals of calcium oxalate and starch grains; secretory canals exist extensively in the cortexes, phloem and piths; neither cortexes nor phloem of roots have thick-walled cells, but cortexes and phloem of the stems of the wood plants have fibers or stone cells. CONCLUSION: The pharmacognostic and interspecies characteristics for wood and herbaceous plants identification were obtained. The wood and herbaceous plants in one natural group of a genus as its two subgenera was sustained by the study result.

Aralia↗
PubMed2001

Vascular endothelial growth factor (VEGF) receptor-2 antagonists inhibit VEGF- and basic fibroblast growth factor-induced angiogenesis in vivo and in vitro.

Exponential tumor growth is angiogenesis-dependent. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are potent angiogenic inducers that act synergistically in vivo and in vitro. We assessed the effect of specific inhibitors of VEGF receptor (VEGFR)-2 tyrosine kinase activity in in vivo and in vitro models of VEGF- and bFGF-induced angiogenesis. In an implant mouse model of angiogenesis, VEGFR-2 inhibitors completely blocked angiogenesis induced by VEGF, and, surprisingly, also inhibited the effect of bFGF to various extents. In vitro, VEGF- and bFGF-induced bovine microvascular and aortic endothelial (BME and BAE) cell collagen gel invasion could be blocked by the VEGFR-2 inhibitors by 100 and approximately 90%, respectively. Similar results were obtained with VEGFR-1-IgG and VEGFR-3-IgG fusion proteins and with VEGFR-2 blocking antibodies. Both BME and BAE cells produce VEGF and VEGF-C, which is not modulated by bFGF. Thus, the unexpected inhibition of bFGF-induced angiogenesis by VEGFR-2 antagonists reveals a requirement for endogenous VEGF and VEGF-C in this process. These findings broaden the spectrum of mediators of angiogenesis that can be inhibited by VEGFR-2 antagonists and highlight the importance of these compounds as agents for inhibiting tumor growth sustained by both VEGF and bFGF.

Angiogenesis Inhibitors↗
PubMed2001

[Use of autogenous cranial bone grafts for orbital floor reconstruction].

OBJECTIVE: To evaluate the effects of autogenous calvarial bone grafts on treatment of the patients with defect of orbital floor from facial trauma. METHODS: During a 5-year period from April 1994 to April 1999, 34 patients ranging in age from 16 to 68 years (twenty males and fourteen females), who presented with orbital floor defects associated with other facial fractures were reconstructed by autogenous calvarial bone grafts. The surgical approach to the orbital floor involved a transconjunctival incision in 31 patients and a subciliary incision in 3 patients. After the orbital floor exploration, the bone graft was harvested through the coronal incision in 29 patients and the parietotemporal region incision in 5 patients. The bone graft was then fashioned to the appropriate size and configuration and fixed to the stable bone of the orbital floor with microplates or screws. RESULTS: The surgical incisions healed well with a minimal scar. There were no infection, extrusion or other complications associated with autogenous calvarial bone graft. There were no cases of optic neuropathy, diplopia and enophthalmos. There was no morbidity in donor sites. One patient had slight ectropion, which lasted three months and became inconspicuous in six months. 8 cases with hypoesthesia of the infraorbital region returned the sensory function within 6 months. 6 patients with enophthalmos were partly corrected. The follow-up period ranged from 6 months to 5 years. CONCLUSION: The orbital floor defects should be managed by early exploration to avoid later complications. The sequel, such as enophthalmos and dystopia or diplopia are much more difficult to correct after bony union. A vast array of autogenous and alloplastic materials have been used to reconstruct the defect of orbital floor. Autogenous bone graft reduces the risk of infection and extrusion. Cranial bone graft produces less donor site morbidity compared with other sites, non-visible scar as the incision is placed within the hair-bearing skin and the conjunctiva. The membranous bone from the skull has been shown to undergo less resorption and greater graft volume survival as compared to endochondral bone of the iliac crest or rib. Skull bone is an ideal source of bone graft in orbital reconstruction.

Adolescent↗
PubMed2001

[Autotrophic ammonium-removal of sludge liquor].

The autotrophic ammonium-removal process was realized in floating bed reactors with sludge liquor as substrate. Biofilm of autotrophic bacteria were formed on the surface of carriers in reactors. The main operation conditions of the reactors were as the following: T = 28 degrees C, pH = 8.0 and DO = 0.8-1.0 mg/L. The average surface load of two reactors in series was NH4(+)-N 3-4 g/(m2.d), and the general autotrophic ammonium-removal efficiency was about 70%. The Autotrophic ammonium-removal technology promises considerable savings in regard to the oxygen consumption and external organic carbon addition compared with the conventional nitrification-denitrification technology when it was used to treat ammonium-rich and unfavourable C/N ratio wastewater.

Biofilms↗
PubMed2001

[Sequencing of inhA in drug-resistant Mycobacterium tuberculosis isolates].

OBJECTIVE: To determine and characterize inhA mutations of drug-resistant isolates of Mycobacterium tuberculosis. METHODS: PCR products of inhA of drug-resistant and susceptible isolates and H(37)R(v) were purified, cloned and analyzed by ABI 377 auto-DNA sequencing system. RESULTS: 11 out of 17 drug-resistant M. Tuberculosis isolates were detected having inhA variations. 10 out of the 11 strains with variations had at least one missense mutation. The variations consisted of point mutation (transition, transversion and deletion). Molecular mechanisms were different from strain to strain. 8 of 13 (62%) strains had both katG and inhA mutations. 18 variation positions and mechanisms different from previous report have been described. CONCLUSION: These results suggested that binding sites decrease caused by inhA point mutations be associated with M. tuberculosis' resistance to INH and EMB.

Amino Acid Sequence↗
PubMed2001

[A novel Fe/AC desulphurizer at low temperature].

Activated coke was used to support Fe2O3(Fe/AC) for flue gas SO2 removal. Reaction conditions on DeSOx activity were investigated. The results show that Fe/AC had higher activity than AC or Fe2O3 at temperature of 120 degrees C-250 degrees C. H2SO4 and Fe2(SO4)3 were formed after Fe/AC sorbed SO2, H2O and O2 increased the amount of SO2 adsorption. Fe/AC derived from AC of higher BET surface area had higher DeSOx activity. Fe/AC was suitable to be used at GHSV below 800 L/(kg.h).

Air Movements↗
PubMed2001

[Retrospective clinical analysis of the emergent comprehensive repair of electrical injury].

OBJECTIVE: To summarize the experience with clinical emergent comprehensive repair of electrical injury. METHODS: One hundred fifty five cases of electrical injury during past 14 years were analyzed in terms of the emergent repair methods on the basis of medical records and photographs. RESULTS: In this group of patients the average interval between injury and hospitalization was 14.9 +/- 21.5 hours, And 108 cases (70%) were admitted to hospital within 2 hours post injury. The average time between admission and first operation was 3.74 +/- 9.89 hours, and 70% of them was within 1 hour after admission. Four hundred and fifty nine wounds were debrided and 296 strips of tendons, 19 strips of blood vessels, 196 pieces of bone or joints and 16 strips of nerves, which were exposed, devitalized or necrotic, were saved. The grafting repair of tendons, bones, nerves and blood vessels was done in 24 case times. Three hundred and ninty eight tissue flaps were employed in 459 wounds. CLS (NS + Lidocaine + amphicol) solution was employed to irrigate underneath the flaps for 24 similar 96 hours or longer. Composite dan -- shen root (scatellaira indica) solution was given to all the patients by injection. As a result, the excellent rate of function and contour was 84.8%. The unsatisfactory and amputation rate was 9.6%. The rate of extremity and/or finer amputation was 1.8%. The rate of total limb loss including those lost instantly after injury was 9%. CONCLUSION: Emergent comprehensive management of electrical injury was a feasible and effective method for decreasing extremity loss.

Adolescent↗
PubMed2001

[An Experimental Study on the diagnosis of high voltage electrical injury by means of biological oxygen consumption measurement].

OBJECTIVE: To investigate the degrees of the degeneration or the necrosis of muscle tissue injured by high voltage electricity as determined by biological oxygen consumption measurement. METHODS: An animal model with high voltage electricity designed in our laboratory was employed in the study. Muscle tissue sized 12 mm x 10 mm x 1 mm at electric burn produced 5 spots of the rabbit injured legs was harvested for the measurement of tissue oxygen consumption for 100s at 2, 8, 14, 24, 48 postburn hours and 5 postburn day. At the same time histological examination was made. RESULTS: One hundred and eighty two pieces of tissue samples were examined. Among them 20 samples with oxygen consumption below 8.7 kpa/100s (43.5%) showed necrosis under LM, while 157 samples with oxygen consumption of 16.9 to 8.78 kpa/100s (84% similar 44%) showed histological necrosis and different degrees of mixed degeneration and normal tissue, and 5 samples with oxygen consumption above 17 kpa/100s (85%) showed normal histological structure. CONCLUSION: The lower the tissue oxygen consumption was, the more severe the tissue degeneration and necrosis were. Oxygen consumption measurement could be valuable in the determination of the degree of tissue injury inflicted by electricity in terms of its convenience, rapidity and accuracy.

Animals↗
PubMed2001

[The mutation of anti-CD3 antibody (HIT3a) gene and its expression].

OBJECTIVE: To improve the expression of anti-CD(3) single chain Fv (scFv) by site mutation and identify its biological activity. METHODS: Anti-CD(3) scFv gene was mutated by PCR, the target clones were screened by both the fingerprints of DNA restriction endonuclease digestion and Western blot, the antigen-binding activity of scFv was examined by FACS, competitive inhibition was performed with (125)I-labeled HIT3a and the cytotoxic effect mediated by the anti-CD(3) scFv-activated T lymphocytes was analyzed by (51)Cr-released assays. RESULTS: The DNA sequencing showed that the 6th amino acid of the anti-CD(3) antibody (HIT3a) heavy chain gene was mutated from E (GAG) to Q (CAG). The expression of mutated anti-CD(3) scFv (m2) was increased by 100 times higher than that of the parent scFv, and there was no difference in the Jurkat cell (CD(3)(+))-binding activity between the (m2) and parent scFv. The preliminary results of competitive assays showed that m2 could partially block the sites of CD(3)(+) Jurkat cells where the parent antibody bound to. Cytotoxicity assays demonstrated that CD(3)AK cells induced by IL-2 and m2 showed stronger cytotoxic effect than that of LAK cells induced by IL-2 alone in vitro. CONCLUSION: By site mutation, a high expression fragment m2 of anti-CD(3) scFv antibody was obtained. The results of some experiments indicated that m2 could bind to CD(3)(+) Jurkat cells, furthermore, by co-stimulated with IL-2, it could activate peripheral T lymphocytes and induce CD(3)AK cytotoxic effect.

CD3 Complex↗
PubMed2001

[Study of specific targeting cytotoxicity mediated by anti-CD(3)/anti-CD(20) Diabody].

OBJECTIVE: To study the specific targeting cytotoxicity mediated by an anti-CD(3)/anti-CD(20) diabody. METHODS: The diabody was purified by affinity chromatography and identified by Western blot assay, size exclusion chromatography, FACS and rosetting assay; the effect of the anti-CD(3)/anti-CD(20) diabody mediated lysis of CD(20)-expressing tumor cells was assayed by (51)Cr release assay in vitro and by human B cell tumor nude mice xenograft model in vivo. RESULTS: The anti-CD(3)/anti-CD(20) diabody could bind both Jurkat cells (CD(3)(+)) and Daudi cells (CD(20)(+)) and appeared to be potent in targeting activated peripheral blood mononuclear cell (PBMC) to lyse Daudi cells in vitro. Furthermore, it inhibited tumor growth and prolonged the survival of mice bearing xenografted Raji cells. CONCLUSION: The diabody proved to be a potent agent for targeting peripheral blood lymphocytes to lyse CD(20) antigen expressing tumor cells in vitro and in vivo.

Animals↗
PubMed2001

[A study of analyzing short-chain fat acid by gradient reversed-phase high-performance liquid chromatography].

OBJECTIVE: The objective of this study is to obtain the optimized separating conditions of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, succinic acid from bacteria using reversed-phase high performance liquid chromatograph (RP-HPLC), and to set up a reliable progress in identifying the end-products of oral bacteria. METHODS: The conditions of separating seven short-chain fat acids were optimized using the method of gradient RP-HPLC. RESULTS: The study showed that the optimal chromatographic parameters were: 1.0 ml/min and 2.0 ml/min of flow rates, and the wavelength of ultraviolet detection was 217 nm. The composition of eluent: the ratio of phosphate buffer (pH 2.8) to methanol is 95:5 (v/v), gradient 5%-50%. The liner gradient wash will be performed in 10 minutes at room temperature. The average recovery rate was 92%, and RSD was 1.8%. CONCLUSION: The results of this paper will be helpful to determine acid composition of end products of oral bacteria.

Chromatography, High Pressure Liquid↗
PubMed2001

[Effects of para-aminobenzoic acid (PABA) on growth of Streptococcus mutans].

OBJECTIVE: The aim of this study is to examine effects of para-aminobenzoic acid (PABA) on the growth of Streptococcus mutans (S. mutans). METHODS: Different concentrations of PABA (10(-10)-10(-3) g/L) were separately transferred to modified Carlsson medium. S. mutans (ATCC 25175) grew in modified Carlsson medium with different concentrations of PABA. All cultures were incubated at 37 degrees C anaerobically in an atmosphere of 80% of nitrogen (v/v), 10% of hydrogen (v/v) and 10% of carbon dioxide (v/v) for 48 hours. The absorbance values of S. mutans were measured by using a spectrometer (UV-1601). The colony forming units (CFU) were obtained by growing S. mutans in media with different concentrations of PABA (10(-10)-10(-3) g/L). RESULTS: Different concentrations of PABA had different stimulating effects on the growth of S. mutans (P < 0.05). But this kind of stimulating effects declined when the concentration of PABA was 10(-3) g/L. CONCLUSION: This experiment indicates PABA has stimulating effects on the growth of S. mutans, and PABA can promote growth of S. mutans.

4-Aminobenzoic Acid↗