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Biomedical subjects

Z G Tang

Publications and source records attributed to Z G Tang.

14 recordsLinked to original sources
PubMed2005

The physical properties and response of osteoblasts to solution cast films of PLGA doped polycaprolactone.

Polycaprolactone films doped with poly(lactide-co-glycolide) (65:35) in 0, 10, 20, and 30 (wt%) were prepared and evaluated in terms of morphology, dynamic contact angle analysis, and thermal properties. The unique surface morphology of the doped PCL film resulted, without introducing significant microstructure disruption of PCL aggregation. The doped PCL film registered a lower contact angle and increased hydrophilicity. Osteoblast cells attached to all doped materials, the 10% and 20% doped materials demonstrating the greatest cell growth.

Actins↗
PubMed2004

Surface properties and biocompatibility of solvent-cast poly[-caprolactone] films.

Poly(epsilon-caprolactone) (PCL) was dissolved in four solvent systems, chloroform, tetrahydrofuran, acetone and ethyl acetate, and cast onto glass Petri dishes. The surface properties of the resulting films were investigated. The extent to which their properties were determined by the solvent used in each case was quantified in terms of contact angle, surface morphology, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and the adhesion and proliferation of fibroblasts by direct contact. The surface of the PCL film in contact with glass was denoted the SG surface, and the other, which was exposed to the gas phase, a mixture of air and residual solvent vapour, was denoted the SA surface. In the case of hydrophobic solvent systems, the advancing contact angle of the SG surface was always lower than that of the SA surface. With hydrophilic solvent systems, on the other hand, the advancing contact angle of the SG film surface was higher when the contact angle of the Petri dish was higher than that of the gaseous mixture of the air and solvent vapour, otherwise it was lower or equal to that of the surface on which it was cast. The surface morphology was dictated by the solubility of PCL in the respective solvent systems: high dissolution solvents such as chloroform and tetrahydrofuran produced films that comprised PCL aggregates, the particles being larger in the case of chloroform, whereas the less efficient solvents (acetone and ethyl acetate) resulted in a filamentous structure. The ATR-FTIR results confirmed that the chemistry of the SA surfaces differed according to the solvent system used. Preliminary cell culture experiments carried out with the PCL films established that murine (L929) fibroblasts grew well on all surfaces regardless of the solvent used, although the rates of adhesion and proliferation were not as great as on tissue culture plastic controls. Of all the surfaces examined in this study, the cells favoured the SG aspect of ethyl acetate cast PCL films, the surface of which had the finest pore size and relatively low contact angle.

Animals↗
PubMed2003

Compression-induced changes on physical structures and calcification of the aromatic polyether polyurethane composite.

It is generally accepted that stress causes calcification in both bio-prosthetic and polyurethane heart valves. However, simple uni-axially- and bi-axially-stretched samples did not yield a feasible model for the elaboration of the stress-induced calcification. In this study, heat compaction combined with the incorporation of polyethylene has been explored. Specimens of polyurethane were solution cast onto a porous bi-axially-drawn ultra-high-molecular-weight polyethylene film and then heat compacted under a pressure of 18 MPa at a chosen temperature for 1.5 h. The heat-compaction-induced calcification and physical changes of the polyurethane composite were evaluated using a 28-day in vitro calcification model and Attenuated Total Reflection-Fourier Transform-Infrared (ATR-FT-IR) spectroscopy. The calcification results indicated that heat-compaction-induced calcification was double that achieved without heat compaction. Heat-compacted polyurethane composite showed higher affinity to calcium ions than the non-heat compacted sample. The ATR-FT-IR results showed that the heat-compaction-induced physical changes include distortions of polymeric molecules and permanent changes of microstructures. The distortions of polymeric molecules could be deteriorated in contact with different media. The relaxation of the stressed structures of the polyether moiety might serve as a calcium trap and a heterogeneous nucleation site for calcification. The permanent changes of microstructures resulted from high distortions also served as affinity sites attracting calcification.

Biocompatible Materials↗
PubMed2001

Effects of Tween-80 on the biodistribution of several lipophilic technetium-99m complexes.

The effects of Tween-80 on the biodistributions in mice of (99m)Tc-TBI, (99m)Tc-MIBI, (99m)TcN-TBI and (99m)TcN-MIBI were reported. The studies resulted that liver and blood uptakes of Tween-80 added (TA) complexes significantly lower than that of corresponding non-Tween-80 added (NTA) complexes. And the clearance rate from blood of TA complexes faster than that of NTA complexes. The optimal concentration of Tween-80 was about 1%. It can decrease the lipophilicity of (99m)Tc-complexes and improve the biological properties of the lipophilic (99m)Tc-complexes for myocardial imaging. It's worthy for further studies.

Animals↗
PubMed2000

The role of cellular trace elements in oral carcinogenesis induced by 4-nitroquinoline 1-oxide(4NQO).

The aim of this study was to define the changes of cellular trace element concentration during the carcinogenesis process of Wistar rat palatine mucosa squamous epithelial cell induced by 4-nitroquinoline-1-oxide (4NQO). 4NQO was painted three times weekly for nineteen weeks on the palatine mucosae of 28 Wistar rats. Histologically normal, precancerous and squamous epithelial cell carcinoma tissues were obtained, and were studied by electron probe X-ray microanalysis. The measured elements were copper (Cu), zinc (Zn), selenium (Se), and molybdenum (Mo). The results were that both copper and zinc in the cellular nucleus and cytoplasm of the squamous epithelial carcinoma cells were significantly decreased. The concentration of cytoplasmic molybdenum significantly decreased in precancerous cells and significantly increased in squamous epithelial carcinoma cells. Minor changes in the concentration of selenium were observed in the process of normal to precancerous and then to cancerous cells. Cu/Zn increased in squamous epithelial carcinoma cells and Cu/Se and Zn/Se decreased in squamous epithelial carcinoma cells. These results suggest that the changes in intracellular copper, zinc, molybdenum are distinctly related to experimental oral carcinogenesis.

4-Nitroquinoline-1-oxide↗
PubMed2000

[The electron probe microanalysis on oral precancer treated by garlic].

OBJECTIVE: To evaluate the effect of 4 kinds of trace elements on experimental oral precancer treated by garlic. METHODS: The palatal mucosae of 42 Wistar rats were painted with 0.5% of 4-nitroquinololine-1-oxide(4NQO) three times weekly for 7 weeks by coating method. Then the animals were divided randomly into two groups. The treatment group was treated three times weekly with garlic solution at the posterior hard palatal mucosae by coating method, and in the control group, the vehicle-distilled water was used instead of garlic solution. At the 5th and 8th weeks of the treatment and the 7th week after the treatment was stopped, some animals were killed. The palatal epithelial cells were prepared and surveyed by electron probe microanalysis. RESULTS: During the treating period, garlic improved the levels of epithelial cells' nuclei copper, selenium, molybdenum and extranuclei selenium, molybdenum(P < 0.01), but it decreased the contents of epithelial cells' extranuclei copper and extra- and intranuclei zinc(P < 0.01). CONCLUSIONS: Garlic can treat the oral precancer by improving the levels of epithelial cells' nuclei copper, selenium, and molybdenum and extranuclei selenium and molybdenum.

4-Nitroquinoline-1-oxide↗
PubMed2000

[Study on trace elements in epithelial cells during oral carcinogenesis prevented by garlic].

Sixty-two Wistar rats were divided randomly into two groups, thirty-one for each group. The posterior hard palatal mucosae of all animals were painted thrice weekly with 0.5% 4-nitroquinoline 1-oxide(dissolved in dimethyl sulfoxide). Before that, the garlic injection solution and the distilled water were painted at the same place of the experimental and control group animals, respectively. All animals were killed in turn from the beginning of the experiment at random at the 10th, 13th, and 19th week. Then, trace elements of intranuclear and cytoplasm of epithelial cells or cancer cells at the mentioned weeks were surveyed by electron probe microanalysis. The results were that garlic decreased the levels of intranuclear and cytoplasm copper(P < 0.05); the levels of intranuclear and cytoplasm selenium at the 10th week and the 13th week(P < 0.05) and those of zinc at the 19th week (P < 0.01) increased. So, garlic inhibits oral carcinogenesis by changing concentrations of intranuclear and cytoplasm trace elements that is copper, zinc, selenium, and the ratio of the three elements.

4-Nitroquinoline-1-oxide↗
PubMed1999

Development of thin elastomeric composite membranes for biomedical applications.

A breakthrough has been made in blending of two immiscible biocompatible polymers to form thin transparent interpenetrating network composite membranes (CM) with exceptional improvement in properties. Two immiscible polymers, namely the biaxially drawn ultra high molecular weight polyethylene (UHMWPE) film and polyether polyurethane (PU) were used. The fabrication included solution casting and heat compaction. During the fabrication, the CM still preserved the orientation of UHMWPE fibers but introduced the interpenetration of PU in UHMWPE film. The intimate interaction of PU with UHMWPE fibers was viewed through the transparency of CM. Differential scanning calorimetry (DSC) data showed the melting temperature (Tm) of UHMWPE increased by about 10 degrees C in CM and about 5 degrees C in heat-compacted membranes (HCM). Morphological observations indicated that CM presented a layered structure while HCM was a dense material without obvious void inclusions. The ultimate tensile strength and relative Young's modulus of CM are about 62 MPa and 460 MPa, respectively. They are about four times greater in strength and 150 times greater in modulus compared with those of PU. Heat compaction resulted in a membrane with nearly five times the tensile strength and 50 times the Young's modulus of PU. The engineered ultimate strain of CM is about 26%, 8% more than that of the porous UHMWPE film while about 70% of HCM, which is a 50% increase achieved through heat compaction. The tensile fracture toughness is about 93 mJ for CM and 211 mJ for HCM, two and five times that for the porous UHMWPE film, respectively. The significant modification on the properties of the heat-compacted composite may raise broad interest in using the CM to develop membrane-related devices and organ covers in biomedical applications.

Journal Article↗
PubMed1984

Hemoglobin Chongqing [alpha 2(NA2)Leu----Arg] and hemoglobin Harbin [alpha 16(A14)Lys----Met] found in China.

Hemoglobin Chongqing is a new slowly-moving and unstable hemoglobin variant with a high oxygen affinity, that was discovered in five members of a Chinese family in the suburb of Chongqing. Hemoglobin Harbin is another new rapidly-moving hemoglobin variant with slightly reduced stability and slightly increased oxygen affinity, found in a Chinese woman living in Harbin. The relative amounts of these two variants in the propositi were about 9% and 18%, respectively. Sequence analyses identified a Leu----Arg substitution at position alpha 2(NA2) of Hb Chongqing, and a Lys----Met substitution at position alpha 16(A14) of Hb Harbin.

Adult↗