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Biomedical subjects

X Cao

Publications and source records attributed to X Cao.

333 records · Page 19Linked to original sources
PubMed1990

[Development of a new system for selection of A. foetidus transformed with foreign genes by using thymidine kinase gene as a marker and expression of HBsAg gene in A. foetidus].

A new system for selection of transformed Aspergillus foetidus was reported. In this system, TK- A. foetidus which were constructed by homologous recombination of mutated TK gene of vaccinia virus with TK gene of A. foetidus were screened by adding BUdR in agar plates. Conditions for screen of TK+ A. foetidus strain, transformation of A. foetidus and selection of transformed TK- A. foetidus have been studied. By using this system, several transformed A. foetidus which contained HBsAg gene derived bf a promoter H8 cloned from genomic DNA of A. foetidus were isolated. It was demonstrated that HBsAg gene was integrated into the chromosome DNA of A. foetidus by Southern blot after many passages of spores. ELISA showed that HBsAg was positive in the growth medium (p/n = 20). The 22 nm particles which were very similar to the HBsAg particles in human serum were found in the growth medium by immunoelectromicroscope. Western blot also gave the specific bands. All these data showed that HBsAg gene was expressed in A. foetidus and the products were secreted into the growth medium. The selection system using TK gene as marker could generally be used to study the expression of foreign gene in A. foetidus.

Aspergillus↗
PubMedDate not supplied

Neural network based temporal video segmentation.

The organization of video information in video databases requires automatic temporal segmentation with minimal user interaction. As neural networks are capable of learning the characteristics of various video segments and clustering them accordingly, in this paper, a neural network based technique is developed to segment the video sequence into shots automatically and with a minimum number of user-defined parameters. We propose to employ growing neural gas (GNG) networks and integrate multiple frame difference features to efficiently detect shot boundaries in the video. Experimental results are presented to illustrate the good performance of the proposed scheme on real video sequences.

Algorithms↗
PubMedDate not supplied

Involvement of opioid peptides of the preoptic area during electroacupuncture analgesia.

The present work was to study the roles of opioid peptides in the preoptic area on electroacupuncture analgesia (EA), and the effects of opioid peptides on noradrenaline (NA) release in the preoptic area during EA. It was found that the pain threshold and the level of [Leu5] enkephalin (L-EK) or beta-endorphin (beta-EP) release in the perfusate were increased during EA, but the NA release from the preoptic area was decreased. Naloxone (15 microM) perfusion significantly reversed the increased pain threshold and the decreased NA release induced by acupuncture. The reversal of pain threshold and the decreased NA release induced by acupuncture. The reversal of pain threshold and NA release by naloxone was dose-dependent. Multimicropipettes and microiontophoresis were also used to study the effect of acupuncture. The inhibition of nociceptive neuronal discharges produced by electroacupuncture was closely related to the etorphine-sensitive neurons, and reversed by microiontophoretic application of naloxone. The results suggest that the inhibitory effect induced by electroacupuncture may be mediated by opioid peptides in the preoptic area.

Acupuncture Analgesia↗
PubMedDate not supplied

Electro-acupuncture (EA) induced attenuation of immunosuppression appearing after epidural or intrathecal injection of morphine in patients and rats.

In order to investigate the effect of epidural morphine and electroacupuncture (EA) on immune function of postoperative patients, peripheral blood for NK (natural killer) cell activity assay were obtained from patients before and on the 1st, 3rd, 7th day after cholecystectomy. 1 mg morphine injected into epidural space after surgery significantly suppressed NK cell activities via prolonged inhibition and increased the inhibitory intensity of it. EA of "Zusanli (St. 36), Sanyinjiao(Sp. 6), Hegu(L.I.4) and Neiguan(P.6) points enhanced the NK cell activities after epidural injection of morphine. It was further observed that microinjection of 1 microgram/1 microliter naloxone into periaqueductal gray (PAG) partially antagonized the suppression of NK cell activity induced by intrathecal (ith) injection of 40 micrograms/50 microliters morphine, and so does EA of "Zusanli(St. 36)". When EA applied after naloxone microinjected into PAG, the NK cell activity was further augmented as compared to that using EA or PAG microinjection of naloxone alone. The above results suggest epidural morphine combined with EA is a better method to relieve postoperative pain, and opiate receptor in PAG might partially mediate the suppression of NK cell activity induced by intrathecal injection of morphine. Yet, the mechanisms of the attenuation of EA on morphine induced immunosuppression needs further study.

Adult↗
PubMedDate not supplied

Intratumoral injection of GM-CSF gene encoded recombinant vaccinia virus elicits potent antitumor response in a mixture melanoma model.

A recombinant vaccinia virus containing and expressing the gene for murine granulocyte-macrophage colony-stimulating factor (VVGM-CSF) was constructed and tested for its antitumor activity. A murine tumor model was established by injecting 10(5) B16F10 melanoma cells into the right rear leg of C57BL/6 mice. Three days after B16F10 inoculation, VVGM-CSF or a thymidine kinase gene-deficient vaccinia virus (VVTK) were injected intratumorly twice weekly for 3 weeks. The results showed that VVGM-CSF treatment significantly inhibited the growth of subcutaneous tumor and delayed the survival period of tumor-bearing mice. Splenic lymphokine-activated killer cell, natural killer cell, and cytotoxic T lymphocyte activities were not found to be altered after VVGM-CSF or VVTK therapy. Cytotoxic and phagocytic activity of peritoneal macrophages were found to be greatly elevated in mice treated with VVGM-CSF. Nitric oxide released from the macrophages was also increased. Considering these data, we may speculate that continuous secretion of GM-CSF and activation of macrophages may contribute to the antitumor effects of VVGM-CSF injected intratumorally.

Animals↗