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Biomedical subjects

X Yi

Publications and source records attributed to X Yi.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Effects of saponins from stems and leaves of Panax quinquefolium L. on the contraction of rabbit aortic strips].

It has been found out that the saponins from stems and leaves of Panax quinquefolium (PQS) can non-competitively antagonize the dose-response curves of norepinephrine (NE), potassium chloride and calcium chloride on the isolated aortic strips of rabbits, and obviously inhibit intracellular and extracellular Ca2(+)-dependent contraction of the aortic strips induced by NE. These effects of PQS are similar to verapamil.

Animals↗
PubMed1995

[Establishment and characteristics of a model of nude mouse xenograft of human retinoblastoma].

The authors reported the establishment and biological characteristics of a model of nude mouse xenograft of human retinoblastoma (RB). Immediately after the enucleation of the human globe with RB, the tumor tissue was transplanted subcutaneously into a nude mouse. The tumor grew constantly and was passaged serially for 14 passages till now. The results of the following examinations of the xenograft and primary tumor were compared: light and electron microscopy, immunohistochemistry, flow cytometry and chromosome analysis. The comparisons reveal that the main biological characteristics of the xenograft model are consistent with those of the primary tumor and also maintain throughout the serial passages. The model can be used for further laboratory studies.

Animals↗
PubMed1995

Purification of 31/32 kDa proteins of adult Schistosoma japonicum as antigens (Sj 31/32) for ELISA and IHA.

Major diagnostic proteins of 31/32 kDa were purified from soluble adult worm homogenate of Schistosoma japonicum using AcA ultragel chromatography and additional treatments. The purity of the isolated antigenic proteins (Sj 31/32) was demonstrated by SDS-PAGE and Western blotting technique. The antigens showed a negative reaction when stained by PAS and remained active after treatment with sodium periodate, moving toward anode in the electrophoretic field. These purified antigens were used for detecting the specific antibody in sera from patients with schistosomiasis japonica by ELISA and IHA. As compared with SEA, Sj 31/32 kDa was found as sensitive as but much more specific than SEA in immunodiagnosis.

Animals↗
PubMed1995

[Comparative study on hepatic and intestinal pathological changes in different animals with schistosomiasis japonica].

The pathological changes of livers and intestines were compared among cats, dogs and rabbits infected with Schistosoma japonicum cercariae for three months. The resuults showed that the most serious lesions were seen in rabbits while the slightest were in cats. The granulomatous response was more distinct in livers than in intestines in all the three animals. The increment ratio of egg granuloma in livers was 3.52, 2.64 and 1.81 in rabbits, dogs and cats, respectively. The eggs were deposited singly or in strings, few granuloma formation was observed in the intestines. In addition to inflammatory infiltration, swelling and/or dropping of mucosa the gland destruction and ulcer were also observed in the mucosa. The investigation demonstrated that pathological lesions varied in different animal species.

Animals↗
PubMed1994

The toxic effects, GSH depletion and radiosensitivity by BSO on retinoblastoma.

Retinoblastoma is the most common intraocular malignant tumor in children. Previous investigations have reported that buthionine sulfoximine (BSO) can deplete intracellular glutathione (GSH) by specific inhibition and increase cellular radiosensitivity. The toxic effects, GSH depletion and radiosensitivity of BSO on retinoblastoma cells are reported in this paper. GSH content of retinoblastoma cell lines Y-79, So-Rb50 and retinoblastoma xenograft is 2.7 +/- 1.3 x 1.0(-12) mmol/cell, 1.4 +/- 0.2 x 1.0(-12) mmol/cell, and 2.8 +/- 1.2 mumol/g, respectively. The ID50 of BSO on Y-79 and So-Rb50 in air for 3 h exposure is 2.5 mM and 0.2 mM, respectively. GSH depletion by 0.1 mM BSO for 24 h on Y-79 cells and 0.01 mM BSO for 24 h on So-Rb50 cells is 16.35%, and 4.7% of control. GSH depletion in tumor and other organ tissues in retinoblastoma-bearing nude mice after BSO administration is differential. GSH depletion after BSO exposure in Y-79 cells in vitro decreases the Do value of retinoblastoma cells. The SER of 0.01 mM and 0.05 mM BSO for 24 h under the hypoxic condition is 1.21 and 1.36, respectively. Based on these observations, the authors conclude that BSO toxicity on retinoblastoma cells depends on the characteristics of cell line and that BSO can increase hypoxic retinoblastoma cells' radiosensitivity in vitro. Further study of BSO radiosensitization on retinoblastoma in vivo using nude mouse xenograft is needed.

Animals↗
PubMed1994

Muscarinic inhibition of cardiac norepinephrine and neuropeptide Y release during ischemia and reperfusion.

It was the aim of the present study to characterize the modulatory effect of muscarinic agonists on the overflow of norepinephrine and neuropeptide Y (NPY) from the in situ perfused guinea pig heart, induced by electrical stimulation of the left stellate ganglion (6 Hz, 5 V, 1 min). The muscarinic agonists oxotremorine (0.01-1 microM) and carbachol (0.1-10 microM) reduced norepinephrine and NPY overflow in a concentration-dependent manner to approximately 30% of control. The inhibitory effect of carbachol was antagonized by the unspecific muscarinic antagonist atropine (1 microM) but not by the nicotinic antagonist hexamethonium (100 microM). The M2-specific antagonist AF-DX-116BS was 25 times more potent than the M1-specific antagonist pirenzepine in antagonizing the inhibitory effect of carbachol [50% inhibitory concentration (IC50) = 0.2 microM for AF-DX-116BS; IC50 = 5.0 microM for pirenzepine]. These findings indicate that presynaptic muscarinic inhibition of stimulated norepinephrine and NPY release from the guinea pig heart is mediated mainly by activation of M2 receptors. As early as 2 min after stop-flow ischemia, the inhibitory effect of carbachol (10 microM) on the stimulation-evoked overflow of norepinephrine and NPY was lost. On reperfusion with oxygenated buffer after 10 min of stop-flow ischemia the inhibitory effect of carbachol (10 microM) on stimulation-induced norepinephrine and NPY overflow recovered within 3 min.

Animals↗
PubMed1994

[The causes responsible for recurrence of pituitary adenomas and an evaluation of reoperation effects].

Four hundred and twenty one cases of transfrontal removal of pituitary adenomas were presented. Of these 23 had recurrence of tumor which was confirmed by reoperation and histopathological examination. The rate of recurrence decreased while the patients' age increased. Incomplete removal of the tumor tissue was one of the most important causes of recurrence. Invasiveness was another important cause. Most of the tumors in this series were large and had pathologically proven invasiveness. At the reoperations, there were evidences of worse invasiveness, especially the infiltration of adenomas into the capsules and adjacent structures. There was a case of Nelson's syndrome, suggesting the endocrine causes of recurrence. Apparent adhesion and topographic disorders were found during reoperation, improvement of visual impairment decreased obviously, and the mortality rate increased; therefore, the reoperations should be decided with great deliberation.

Adenoma, Chromophobe↗
PubMed1993

Does guanine concentration in house-dust samples reflect house-dust mite exposure?

Using specific ELISA extracts, we analyzed samples of pure mite cultures and house dust for group I allergens from Dermatophagoides pteronyssinus, D. farinae, and D. microceras. Correspondingly, we measured the concentration of guanine and xanthine by rigorous chemical methods. The pure mite cultures were used to correlate allergen levels with guanine levels. The house-dust samples one-sidedly contained more guanine than expected. This suggests that considerable amounts of guanine originate from non-house-dust mite sources and implies that guanine quantifications are of limited clinical value.

Allergens↗
PubMed1991

[Relation between the levels of estrogen receptor and progesterone receptor and clinicopathological status in human endometrial carcinomas].

Estrogen receptor (ER) and progesterone receptor (PR) assays were performed by direct fluorescent histochemical methods in 20 endometrial carcinomas and 9 endometria of para-carcinomas. ER + and PR + were found in the patients who had not received chemotherapy and/or radiotherapies. In 4 adenosquamous carcinomas, the contents of ER and PR of adenocarcinoma components were higher than those of squamous carcinoma components. Blocking tests proved the specificity of ER and PR for estradiol and progesterone respectively. The levels of ER and PR in endometria of para-carcinomas were higher than those in carcinomas. There were higher levels of ER and PR in early clinical stage than in advanced stage, in cases free from cervical involvement than in cases cervical involvement, and in well differentiated carcinomas than in poorly differentiated carcinomas. ER and PR contents did not correlate with the depth of myometrial invasion or menopausal status. In the patient group followed up for half a year or more, 4 patients with high-level ER and PR had a good response to 17 alpha-progesterone caprate. The patients with ER + and PR + had a longer survival period than those with ER- and PR-. Our results indicated that the assay of ER and PR might be valuable for predicting the response to endocrine therapy and prognosis for patients with endometrial carcinoma.

Adenocarcinoma↗
PubMed1991

[The sensitization of acoustic stapedius reflex].

The acoustic stapedius reflex, which normally occurs at a hearing level of about 85 dB, can be detected at lower levels by means of sensitization. The technique is to apply reflex-eliciting tone and the facilitating tone stimulation. The high-frequency acoustic stapedius reflex can then be detected in this procedure under low-frequency facilitating. When hearing is normal, significant difference can be demonstrated between conventional and facilitated reflex threshold. There is a great amount of reflex threshold improvement with sensitization. Sensorineural hearing loss allowed small or no reflex threshold change with sensitization.

Acoustic Impedance Tests↗
PubMed1990

[Identification and typing of Actinobacillus actinomycetemcomitans by restriction endonuclease analysis].

The aim of the present study was to investigate the potential of restriction endonuclease analysis (REA) for the identifying and typing of Actinobacillus actinomycetemcomitans (Aa). Bacterial chromosomal DNA was extracted and digested with BamHI, HindIII, Sal I and Xho I respectively and separated by agarose gel electrophoresis. DNA fragment patterns of Aa and Haemophilus aphrophilus differed strikingly from each ether. The patterns of Aa FDC Y4 and Aa ATCC 29523, belonging to two different serotypes, also differed notably. Among the 4 enzymes used, Sal I and Xho I gave the most satisfactory results. The results of our work suggested that REA could be used to identify and type Aa. REA is stable, sensitive, accurate and reproducible. The method might be valuable in molecular epidemiologic studies on periodontopathic organisms.

Actinobacillus↗
PubMed1989

A cDNA clone encoding part of the major 25,000-dalton surface membrane antigen of adult Schistosoma mansoni.

Immunoscreening of an adult Schistosoma mansoni cDNA expression library, using antibodies raised against purified adult worm tegumental surface membranes, identified a recombinant clone containing a 141-bp insert. Antibodies raised against the recombinant antigen bound specifically to the tegument of adult worms and immunoprecipitated the major 25,000-dalton surface membrane antigen as well as a 22,000-dalton nascent polypeptide generated by cell-free translation of adult S. mansoni mRNA. The mature 25,000-dalton antigen was found to be precipitated by antibodies from infected mice, rats and humans.

Amino Acid Sequence↗