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Biomedical subjects

Z Cao

Publications and source records attributed to Z Cao.

244 records · Page 14Linked to original sources
PubMed1990

[Primary serologic investigation of HBV-like virus existence in domestic animals and fowls].

Using the reagent kits for detecting human HBV, primary serologic investigation was made in 6 kinds of domestic animals and fowls (total 673) by ELISA, spot hybridization and immuno-electronmicroscopy. The results showed that some sera samples of pigs, rabbits, chicken and geese were HBsAg, HBeAg positive and positive for spot hybridization by using 3(2)P-HBV-DNA probe, which suggested that HBV-like viruses might exist in those domestic animals and fowls. HBV-like virus particles were seen in one pig serum sample which was HBsAg positive. The particles could be divided into three forms in shape, large spherical particle (40-55nm), small spherical particle (20-30nm) and short filament particle. The further studies are needed.

Animals↗
PubMed1989

Dual functions of a cis-acting element within the rat prolactin gene promoter.

Within the promoter region of the rat prolactin gene lies a TA-rich imperfect palindrome. The possible functions of the 18-base-pair symmetrical sequence were investigated by using an in vitro transcription system. Prolactin templates with and without the palindrome were transcriptionally assayed in both pituitary and nonpituitary extracts. Our results indicated that the palindromic sequence has at least two functions in the regulation of prolactin transcription.

Animals↗
PubMed1986

Capillary permeability changes in the uteri of recipient rabbits after transfer of blastocysts from indomethacin-treated donors.

Blastocysts recovered from control or indomethacin-treated (10 mg/kg s.c. twice daily starting on Day 4.5 of pregnancy) donor rabbits were transferred to the uteri of Day-6 or 6.5 pseudopregnant recipients. The minimal time required to cause an increase in capillary permeability in the endometrium underlying control blastocysts was approximately 9 h. Blastocysts derived from the indomethacin-treated donors were depleted of PGE and PGF (determined by RIA) and were unable to produce any increase in capillary permeability during the same time period, although after 46 h in vivo the diameters of the implantation swellings related to control or indomethacin-treated blastocysts were not different. This suggests that, in the untreated recipients, blastocysts depleted of PGs can become replenished and then release these PGs in a site-directed manner. Indomethacin thus causes a delay rather than a complete inhibition of implantation. Incubation of the indomethacin-treated blastocysts in vitro led to replenishment with PGs, but such replenished blastocysts failed to induce an increase in capillary permeability within the same time-frame as control blastocysts. Evidence is presented that indomethacin is probably not the cyclooxygenase inhibitor of choice, since it interferes with PG uptake and efflux. Such an action could explain the failure of the replenished blastocysts to induce a normal increase in capillary permeability.

Animals↗
PubMedDate not supplied

Performance characteristics of transmission imaging using a uniform sheet source with parallel-hole collimation.

Transmission imaging is receiving increasing attention in SPECT due to the need to compensate for nonuniform attenuation in cardiac-chest SPECT. The quality of a transmission image has an important effect on the measured attenuation distribution. To improve image quality, knowledge of the performance characteristics of a transmission imaging system is essential. The characteristics, spatial resolution, detection efficiency, photon flux, and exposure to the object, of a transmission imaging system consisting of a gamma camera and a uniform sheet source have been studied. The results demonstrate that spatial resolution of a transmission imaging system can be improved by use of a high-resolution source collimator at the price of a moderate decrease in detection efficiency, in comparison to the uncollimated case. Also, the source collimator significantly reduces the photon flux and exposure to the object. This investigation suggests that a high-resolution collimator be used with an intense sheet source to improve spatial resolution and reduce statistical noise with low exposure to the patient. This research further suggests that the amount of source activity is determined by the requirement of image quality, detection geometry, and allowed absorbed dose to the patient.

Humans↗
PubMedDate not supplied

Lipofection indirectly increases expression of endogenous major histocompatibility complex class I molecules on tumor cells.

Direct intratumoral injection of a lipid/DNA complex encoding an allogeneic major histocompatibility complex (MHC) class I molecule leads to regression of both an immunogenic murine tumor and also melanoma lesions in some patients. We have sought to understand the mechanism(s) for this augmentation of antitumor activity. While optimizing parameters for in vitro gene transfer into the D5 subclone of B16BL6, it was noted that lipofected tumors not only expressed the new alloantigen but also exhibited increased expression of endogenous MHC class I, both H-2 Kb and H-2 Db. This increase in expression was not restricted to the small percentage of cells that expressed the transfected gene, but appeared to affect the majority of cells in culture. Class I expression was not increased by lipopolysaccharide, DNA alone, lipid, or lipid/lipopolysaccharide mixtures. Enhanced class I expression required a DNA/lipid complex and was greatest when parameters optimized for gene transfer of the alloantigen were used. All DNA plasmids tested had this effect, including one plasmid whose DNA was not transcribed because it lacked an expression cassette. Because of the critical role that MHC class I antigens play in immune recognition, we propose that lipid complex-mediated gene transfer may provide immunological advantages beyond those that are attributable to expression of the specific gene transferred.

Animals↗