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Biomedical subjects

X Yan

Publications and source records attributed to X Yan.

At least 163 records · Page 9Linked to original sources
PubMed1995

[A new zoonosis--investigation of Gardnerella vaginalis disease of fox. III. Epidemiological investigation].

By epidemiological investigation to Gardnerella vaginalis disease of fox of civil main farms raising foxes, this disease was showed to be susceptible to silver foxes, arctic foxes, red foxes and color foxes, the disease was mostly transmitted by copulation, infected foxes played the leading role in epidemic of the disease. Investigative results of all farms raising foxes showed infection rate of fox groups was 0.9-21.9%, resulting in abortion rate was 1.5-14.7%, empty rate was 3.2-47.5%. Serious harm was revealed to the disease. By serology and causative agent isolation, we had proved that the disease was able to infect feeder and manager, it belongs to zoonosis. Racoondog. mink and canine infect with the disease besides fox. White mouse, big white rat, gopher, guinea pig and rabbit for laboratory are not infected with the disease.

Abortion, Veterinary↗
PubMed1995

A complex of intermediate filament protein-DNA: a target for autoantibodies in systemic lupus erythematosus?

Autoantibodies in systemic lupus erythematosus which cross-react with double stranded DNA and intermediate filament proteins are frequently reported. However, little is known about the origin and the target of these antibodies. In this paper, a polyspecific monoclonal antibody, XY12, produced by the immunization of genetically non-autoimmune mice with a DNA-protein complex is detailed. Its antigen binding patterns are very similar to the autoantibodies. The data suggest that these autoantibodies may be triggered by a circulating nucleoprotein.

Animals↗
PubMed1995

[A new zoonosis--investigation of Gardnerella vaginalis disease of fox. I. Causative agent isolation and artificial infection].

It is the first time that this paper reports on using improved rabbit blood agar culture medium to isolate 145 strains Gardnerella vaginalis from the foxes and their abortion fortus organs of main fox farms. Among the strains, 26 strains were isolated from the abortion foetus organs, isolation rate was 92.86%; 118 strains were isolated from the vaginal exeretion of the abortion and empty foxes, isolation rate was 34.01%; 1 strain was isolated from inguinal lymph node of the pelted positive fox, isolation rate was 2%. None was isolated from blood. By causative agent isolation, we revealed the bacterium survival position in vivo, and the best isolation route isolation opportunity and isolation methods were selected. By artificial infection test, we have proved pathogenicity of the bacterium.

Abortion, Veterinary↗
PubMed1995

[A new zoonosis--investigation of Gardnerella vaginalis disease of fox. II. Identification of pathogenic bacteria].

16 strains isolated from aborted foetus and vaginal exeretions of foxes were used for examination of cell morphology including fine structure of the cell wall and septa, test for homolysis, biochemical reactions and analysis of G+C content of the bacterial DNA. The cells are pleomorphic bacilli and coccobacilli, Gram stain reaction appear positive to variable, catalse and oxidase-negative, with a fermentative type of glucose metabolism, giving acetic and lactic acid as the major end products of fermentation. It's differentiated from the human strains of G. vaginalis by its less fastidious in growth requirements and being facultatively anaerobic to aerobic. We propose the name: a new subspecies--Gardnerella vaginalis subsp. fox, the type strain is U80.

Animals↗
PubMed1995

Cloning, expression and characterization of a single-chain antibody PS-9 targeted to pancreatic cancer.

Genes encoding single-chain antibodies have been first constructed, which consist of the heavy and light chain variable domains of antibody PS-9 joined together by a flexible peptide linker. The genes were cloned into coat protein g3p genes of pCANTAB5 phagemids, and expressed as fusion proteins on the phage tips. Immunological assay demonstrated that the engineered antibodies specifically bound to cancer cells LS-174-T as well as to pure bovine submaxillary gland mucin. Their specificity and affinity appeared the same as their parent antibodies. Our results supposed that the single-chain antibodies will be a target for the diagnosis and treatment of cancer.

Antibodies, Monoclonal↗
PubMed1995

Lymphocyte proliferation response to S antigen in patients with uveitis and optic neuritis.

PURPOSE: To evaluate the autoimmunity which may play a major role in the etiology of certain forms of uveitis and optic neuritis. METHODS: Lymphocyte proliferation response to retinal soluble antigen in vitro by incorporation 3H-thymidine with DNA was tested in 115 patients with anterior uveitis, posterior/pan-uveitis, optic neuritis, and 50 volunteers with unrelated diseases such as congenital ptosis, strabismus, or completely healthy persons as control. RESULTS: The positive rate of lymphocyte stimulation was 34% (18/53) in anterior uveitis, 41.5% (17/41) in posterior/pan-uveitis, and 57.1% (12/21) in optic neuritis. The results in the experimental groups were significantly different from those of the control group (X2 = 14.76, P < 0.05, x2 = 19.14, P < 0.005, x2 = 26.38, P < 0.005, respectively). CONCLUSION: The autoimmunity plays a role in the pathogenesis in certain forms of uveitis and optic neuritis. Such immune responses may be secondary to the exposition or release of retinal antigens by various causes, leading to activation or augmentation of meager or low-affinity S antigen specific lymphocytes which may pre-exist in the circulation and starting the pathogenic autoimmune process.

Adolescent↗
PubMed1995

[Comparative experiment of gas chromatography determination of Mycobacterium bacillus].

Using capillary column gas chromatography (GC) technique for detecting cellular fatty acid, the test of the GC chromatograms of 26 reference Mycobacteria strains (freeze-dried strains and transfer growed strains at the improved Lowenstein-Jensen culture for three or four weeks) was performed. On the basis of the test, a comparison was made between the GC method and the conventional method for determination of 54 strains of non-tuberculous mycobacteria which were separated from clinical specimens, and the conformational rate of the two methods was 94 percent. At the same time, the relationship between the drug resistance and the changes of GC chromatograms of M. tuberculosis and M. bovis which were separated from clinical samples was observed. The results demonstrated that the GC method would achieve better results if combined with the bacterial growing speed, the condition of producing colour and the condition of growing at PNB and TCH culture during determining the mycobacterium strains which were separated from clinical specimens.

Chromatography, Gas↗
PubMed1994

Prevention by dehydroepiandrosterone of the development of mammary carcinoma induced by 7,12-dimethylbenz(a)anthracene (DMBA) in the rat.

The concentration of serum dehydroepiandrosterone sulfate (DHEA-S) and DHEA decreases markedly during aging, and low circulating levels of DHEA have been associated with a higher incidence of breast cancer in women. Using 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat as model, we have studied the effect of increasing serum levels of DHEA released from Silastic implants on the incidence of these tumors in the rat. Treatment with increasing doses of DHEA leading to serum DHEA levels comparable to those observed in normal adult women (7.1 +/- 0.6 nM and 17.5 +/- 1.1 nM) caused a progressive inhibition of tumor development from 68% bearing tumors in control animals to 22% and 11%, respectively. The average tumor area per rat decreased from 2.81 cm2 in intact control animals to 0.96 and 0.09 cm2 in the groups treated with the same doses of DHEA, respectively. The present data indicate that circulating levels of DHEA similar to those found in normal adult premenopausal women exert a potent inhibitory effect on the development of DMBA-induced mammary tumors in the rat, thus suggesting the possibility of a new and more physiological approach for the prevention of breast cancer in women.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Hydroxyl radicals generated in vivo kill neurons in the rat spinal cord: electrophysiological, histological, and neurochemical results.

We have used microdialysis to establish an experimental model to characterize mechanisms whereby released substances cause secondary damage in spinal cord injury. We use this model here to characterize damaging effects of the hydroxyl radical (OH.) in vivo in the spinal cord. OH. was generated in vivo by pumping H2O2 and FeCl2/EDTA through parallel microdialysis fibers inserted into the spinal cord. These agents mixed in the tissue to produce OH. by Fenton's reaction. Two types of control experiments were also conducted, one administering only 5 mM H2O2 and the other only 0.5 mM FeCl2/0.82 mM EDTA. During administration of these chemicals, electrical conduction was recorded as one test for deterioration. OH. blocked conduction completely in 2.5-5 h and Fe2+/EDTA partly blocked conduction, but H2O2 alone did not cause detectable blockage. Histological examination supported the hypothesis that neurons were killed by OH., as Fe2+/EDTA and H2O2 alone did not destroy significant numbers of neurons. OH., H2O2, and Fe2+ all caused gradual increases in extracellular amino acid levels. These results are consistent with Fe(2+)-catalyzed free radical generation playing a role in tissue damage upon spinal cord injury.

Animals↗
PubMed1994

[Studies on specific diagnostic antigen for filariasis].

Soluble antigens of adult worms (MAA) and microfilariae (MFA) were analysed by means of SDS-PAGE and enzyme-linked immunoblotting (ELIB). The adult worms and microfilariae were collected from abdominal cavity of Mongolian jirds infected with Brugia malayi. The results indicated that MFA shared 64-67 kDa and 56-58 kDa protein components with the peritoneal fluid of the normal jirds. Sera from normal jirds were found to recognize 60 kDa, 74 kDa and 100 kDa fractions of MFA, but did not recognize any bands of MAA. Sera from positive jirds which were infected with B. malayi for 6 months could recognize 42 kDa and 14.5 kDa of MAA, but sera from negative jirds could not. The results indicated that the 42 kDa and 14.5 kDa protein components of MAA might be specific diagnostic antigen fractions.

Animals↗
PubMed1994

[The physiological function of plasma apoA-I--the anti-viral effects of apoA-I and its fragments].

Apolipoprotein A-I (apoA-I), the major protein of plasma high density lipoproteins, was found to inhibit herpes simplex virus type I (HSV-I) induced cell fusion at physiological concentrations (mumol/L). Plasma apoA-I from three different species was used to study the anti-viral effects by microneutralization test. Marked inhibition of virus-induced cell fusion was observed when the virus or the cells were pretreated with apoA-I, suggesting that apoA-I may have a direct effect on the virus and the cells. This function may be related to the structure of apoA-I.

Animals↗
PubMed1993

[The influence of indapamide on 6-keto-PGF1 alpha, PGE2, and PGF2 alpha synthesis and plasma TXB2 levels in spontaneously hypertensive rats].

The influence of indapamide on the prostaglandin system was studied in spontaneously hypertensive rats (SHR) and compared with SHR control and normal WKY rats. The results show that the synthesis of vasoconstrictive prostaglandins (PGE2 and PGF2 alpha) in the renal medullary tissues of SHR is higher than that of normal rats, and this may have something to do with the development and maintenance of high blood pressure in SHR. After indapamide administration, the synthesis of prostacyclin in SHR aorta increased significantly as compared with the SHR control group, whereas PGE2 and PGF2 alpha production in renal medullary tissues decreased markedly. The results support the idea that the prostaglandin system, especially PGE2 and PGF2 alpha, plays an important role in the antihypertensive mechanism of indapamide.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Ultrastructural study of moniliformin induced lesions of myocardium in rats and mice.

Effects of moniliformin on the ultrastructure of the myocardium of mice and rats were studied. Mice were given moniliformin orally at a dose of 29.46 mg.kg-1 the LD50. One h after dosing, lesions of the mitochondria of the myocardial cells were found which became more severe in 2 and 3 h. Ultrastructural lesions were also observed in the myofibrils and sarcolemma. Rats were given moniliformin orally at the dosage of 6 mg.kg-1 once daily for 56 d. Lesions of mitochondria and myofibrils were relatively mild. In the myocardiac specimens taken from the 21d post-toxin administration, lesions of the sarcolemma became more obvious. These moniliformin-induced lesions were similar to the ultrastructural changes in the myocardium of patients with Keshan disease. Our findings indicate that there may be a close and important relationship between moniliformin intoxication and Keshan disease.

Animals↗
PubMed1992

Genomic mapping by single copy landmark detection: a predictive model with a discrete mathematical approach.

One of the goals of the Human Genome Project is to produce libraries of largely contiguous, ordered sets of molecular clones for use in sequencing and gene mapping projects. This is planned to be done for human and many model organisms. Theory and practice have shown that long-range contiguity and the degree to which the entire genome is covered by ordered clones can be affected by many biological variables. Many laboratories are currently experimenting with different experimental strategies and theoretical models to help plan strategies for accomplishing long-range molecular mapping of genomes. Here we describe a new mathematical model and formulas for helping to plan genome mapping projects, using various single-copy landmark (SCL) detection, or "anchoring", strategies. We derive formulas that allow us to examine the effects of interactions among the following variables: average insert size of the cloning vector, average size of SCL, the number of SCL, and the redundancy in coverage of the clone library. We also examine and compare three different ways in which anchoring can be implemented: (1) anchors are selected independently of the library to be ordered (random anchoring); (2) anchors are made from end probes from both ends of clones in the library to be ordered (nonrandom anchoring); and (3) anchors are made from one end or the other, randomly, from clones in the library to be ordered (nonrandom anchoring). Our results show that, for biologically realistic conditions, nonrandom anchoring is always more effective than random anchoring for contig building, and there is little to be gained from making SCL from both ends of clones vs. only one end of clones.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosome Mapping↗
PubMed1992

Short-term experiments on ion transport by seedlings and excised roots : technique and validity.

The absorption of K(+) by excised roots of barley (Hordeum vulgare L. cv California Mariout) has been systematically compared with that of entire, undisturbed seedlings. Some experiments have also been done with wheat (Triticum aestivum L.) and an amphiploid obtained from a cross between it and salt-tolerant tall wheatgrass (Lophopyrum elongatum Host Löve [syn. Agropyron elongatum Host]). For all three genotypes, the rate of K(+) absorption measured in a 20-min period was identical for entire 8-d-old seedlings and their excised roots within the experimental error. Manipulation gentler than root excision, viz. careful transfer of seedlings from one experimental solution to another, was also without effect on the rate of K(+) absorption. Absorption of K(+) measured by assay of its (86)Rb label in the tissue was identical with that measured by K(+) depletion of the experimental solutions assayed chemically. For the plant materials and conditions of these experiments, the excised root technique for studying ion transport into roots is validated. The advantages of the technique, and findings differing from the present ones, are discussed.

Journal Article↗