Biomedical subjects

Y Chen

Publications and source records attributed to Y Chen.

At least 973 records · Page 54Linked to original sources

PubMed2000

[Preclinical pharmacological study of a novel myocardial perfusion agent: 99mTc-Q3].

In order to provide an experimental foundation for clinical study, we made a preclinical pharmacological investigation of 99mTc-Q3, a novel myocardial perfusion imaging agent, technetium-99m-N,N'-ethylenebis (acetylace-toneiminato) bis (tris (3-methoxy-1-proply) phosphine). After the preparation of this compound, the kinetics of blood clearance in rabbits, biodistribution in mice, measurement of plasma protein binding rate, and myocardial perfusion imaging in dog were carried out. The labelling efficiency and radiochemical purity measured were over 99%, and the stability (in vitro) was good and stable up to 6 hr of testing at room temperature. The pharmacokinetics met the two-compartment model with 0.23 +/- 0.09 ml/min of excellent blood clearance, an initial half-time of 1.5979 +/- 0.4182 min, and a late half-time of 203 +/- 25.83 min. The biodistribution as shown in myocardial accumulation was earlier, the radioactive value was higher, and once extracted, it remained relatively constant in the myocardium for at least 4 hr. The tracer was rapidly cleared from the blood, lung and the liver. The scintigraphy imaging in dog demonstrated that it was rapidly cleared from the lung, and the radioactive concentration approached that of background 1 hr after injection. At 15 min after injection, the myocardial imaging displayed clearly up to 3 hr. In vitro protein binding rate was low (7.13 +/- 0.42%). The tolerance of this drug in mice was 500 times as much as in humans. In conclusion, 99mTc-Q3 exhibits favorable stability, biological property and safety, so clinical study of this preparation as a myocardial perfusion imaging agent is worthwhile.

Animals↗

PubMed2000

[Study on the xenoantigens of pancreatic tissues of Chinese Neijiang pig].

The expression and distribution of xenoantigens in pancreatic tissue of Neijiang pig were investigated with immunohistochemistry technique. BSIB4, normal human serum and anti-human A, B, H monoclonal antibodies were used as the primary antibody to examine the expression of xenoantigens in the pancreatic tissues from 10 Neijiang pigs. The results demonstrate that compared with the negative results of human blood B and H type antigens, the alpha-Gal antigen was highly expressed on the pancreatic vascular endothelial cells and the duct epithelium. The human blood A type antigen was highly expressed on some islet cells, some exocrine secretory cells and all the duct epithelium. Since there are pre-exited xenoantibodies against pig pancreas cells in human serum, cross-matching test and graft pre-treatment are needed before clinical transplantation of pancreas. The expression of xenoantigens in Neijiang pig is different from other pig strains reported by others, which suggests that looking for a pig strain that contains less xenoantigens is possible.

ABO Blood-Group System↗

PubMed2000

[P53 delta 37 protein exhibits 3'-5' exonuclease activity].

Mummenbrauer et al. (1996) found that P53 protein exhibits 3'-5' exonuclease activity. This exonuclease activity is intrinsic to wildtype P53 protein, dependent on Mg2+, and it can be inhibited by addition of 5 mmol/L nucleoside monophosphates. In the present study, we intended to know whether mutated P53 protein--P53 delta 37 has this 3'-5' exonuclease activity or not. The results reveal that P53 delta 37 also has 3'-5' exonuclease activity. It has more protein and more exonuclease activity, but this activity can not be inhibited by guanine monophosphate. There are many processes related to exonuclease activity in mammalian cells; for example, DNA replication, DNA recombination and DNA repair. The exonuclease activity of P53 delta 37 protein may be important in these processes.

Exodeoxyribonuclease V↗

PubMed2000

[Study of estrogen and progesterone receptors in endometrial carcinoma].

This study was conducted to immunohistochemical and biochemical measurements of estrogen receptor (ER) and progesterone receptor (PR) in endometrial carcinoma and elucidate the relationship between ER/PR contents and the clinico-pathologic features. Specific monoclonal antibodies to human ER and PR were used and the immunohistochemical (IHC) assay was performed on 36 specimens of endometrial carcinomas. Twenty-eight out of 36 specimens' ER and PR contents were also measured by dextran-coated charcoal analysis (DCC). ER and PR positive rates were 44.4% and 52.8% by IHC, and 50% and 57.1% by DCC, respectively. The two methods correlated significantly, the correlation coefficient between DCC and IHC being 0.565 for ER and 0.563 for PR (P < 0.05). ER and PR contents were much lower in grade 3 than in grades 1 and 2 endometrial carcinomas (P < 0.01). The authors conclude that the levels of ER and PR are associated with the differentiation of endometrial carcinoma. The immunohistochemical and biochemical methods correlate well. A combination of the two methods may be more useful in predicting the prognosis and choosing the treatment.

Adenocarcinoma↗

PubMed2000

[Resources distribution and pharamacognostic identification of Centella asiatica (L.) urban produced in China].

OBJECTIVE: To investigate the resources distribution and morphological histology of Centella asiatica distributed in China, and offer evidences for exploiting the plant resources and drafting the quality standards. METHOD: Sample collection, document investigation and microscopic section observation. RESULT: A table of resources distribution was worked out, the medicinal properties and the microscopic characteristics of the stem, leaf and stipe were described. CONCLUSION: This study supports the viewpoint of Urban and can be used as a reference for the quality standard of Centella asiation.

Centella↗

PubMed2000

[The expression of cell adhesion molecules on lymphatic endothelial cells in rectum adenocarcinoma of human].

This study was conducted to explore the mechanism of lymphatic dissemination and metastasis of cancer cells; the specific aim was to investigate the expression of cells adhesion molecules on lymphatic endothelial cells. Immunohistochemical method was used. The rectum tissues and lymphnodes were taken from five normal human subjects. The cancer peripheral tissues and lymphnodes, and the metastasized lymphnodes were taken from eight patients with rectum adenocarcinoma. The result showed that the intercellular adhesion molecule-1 (ICAM-1) and carcinoma embryonic antigen (CEA) were expressed on lymphatic endothelial cells in cancer peripheral tissues and metastasized lymphnode. The expression of ICAM-1 and CEA in cancer peripheral tissues and lymphnodes was much more remarkable than that in metastasized lymphnodes. These data suggest that ICAM-1 and CEA be cell adhesion molecules between cancer cells and lymphatic endothelial cells.

Adenocarcinoma↗

PubMed2000

[Establishment and application of a computerized radiography cephalometrics system].

We have developed a new-typed computerized radiography cephalometrics and prediction system. It includes cephalometrics, growth prediction, orthopedics/orthodontics prediction and profile prediction. In this study, 47 lateral cephalograms were randomly selected to process a reliability test. The results showed the two groups were in agreement on all of the 25 measurement index. The system is easier, quicker and less prone to error than traditional cephalometrics approach. It is convenient for orthodontists.

Cephalometry↗

PubMed2000

[Methodological study on preparation of a novel myocardial perfusion imaging agent: 99mTc-Q3].

This study was intended to explore the methods of preparing technetium-99m-N, N'-ethylenebis (acetylacetoneiminato) bis [tris (3-methoxy-1-propyl) phosphine] (99mTc-Q3) as a newer cationic myocardial perfusion imaging agent. The optimum scheme of technetium labeling on the basis of exploring the effects of differently labeled conditions on radiochemical purity was established by a multivariate orthogonal experimental design. A newer agent for myocardial perfusion imaging was developed based on the optimum scheme by a stannous chloride reduction method. Preparation, separation, purification and quality control were performed by a chromatography. Experiments for stability (in vitro), sterility, apyrogen, safeness, and for imaging in animals were carried out. "A2B2C2" was chosen as the optimum scheme of this labeled complex. There each of A, B and C factors has significant effect on the radiochemical purity, and there is no one-class cross effect on the radiochemical purity between them. The labeling efficiency and radiochemical purity were measured over 99% labeled 10 min later (at R. T.). The stability (in vitro) was good and kept up to 4 hr or testing (range: 92%-99.37%). The prepared product was sterile, apyrogenic and safe. The scintigraphic imaging in rabbits demonstrated that the tracer accumulated early in the heart and the myocardial imaging displayed clearly up to 3 hr. The results of this methodological study demonstrate that not only high quality 99mTc-Q3 can be obtained but also a standardized procedure for labeling all kinds of 99mTc-agents can be set up, and on this basis, the one-step kit of 99mTc-Q3 may be developed.

Animals↗

PubMed2000

[Effects of 6 kinds of metal elements on meiotic maturation and in vitro fertilization on mouse oocyte].

To study the effects of Cd, Pb, Ni, Mn, Cr and Al on reproductive toxicity, the meiotic maturation and in vitro fertilization(IVF) of mouse oocytes were studied using in vitro culture and IVF of mouse oocytes. The results showed that except Al(NO3)2, the other groups [CdCl2, Pb(NO3)2, NiCl2, MnSO4 and CrCl3] could significantly reduce the number of superovulation oocyte. All of them could inhibit the meiotic maturation, the rates of IVF and extruding of the first polar body, but there was no impact on the germinal vesicle breakdown (GVBD) in vivo. The results also showed that except Al(NO3)3, other elements could obviously inhibit germinal vesicle breakdown of mouse oocytes. The results suggested that these elements might damage the process of meiotic maturation of oocyte of women at child-bearing age oocyte and reduce the fertility and reproductive capacity and result in sterile.

Animals↗

PubMed2000

[Effects of alpha-tocopherol and beta-carotene on the oxidized low density lipoprotein induced by Cu2+].

The effects of different concentrations of alpha-tocopherol and beta-carotene on low density lipoprotein(LDL) oxidation were examined. LDL was oxidized by Cu2+ in a cell-free(10 mumol/L Cu2+ in PBS) system. The results showed that alpha-tocopherol and beta-carotene inhibited the oxidative modification of LDL in this system as evidenced by a concentration-dependent decrease in lipid peroxide(thiobarbituric-acid-reasting substances activity, TBARS) and the electrophoretic mobility of LDL. The effect of alpha-tocopherol on the generation of TBARS was stronger, while on the electrophoretic mobility was weaker than that of beta-carotene. Both alpha-tocopherol and beta-carotene slightly but not significantly reduced lipofusin. It suggested that the mechanisms were different. Thus, beta-carotene, as well as alpha-tocopherol, inhibit LDL oxidation and might play important roles in reducing the generation of oxidized LDL.

Antioxidants↗

PubMed2000

[Studies on chemical constituents of Cistanche tubulosa (Schenk) R. Wight].

OBJECTIVE: To investigate the chemical constituents of Cistanche tubulosa. METHOD: The chemical constituents were isolated by solvent extraction together with various chromatographic techniques including preparative HPLC. The structures were elucidated on the basis of chemical evidence and spectral data. RESULTS: Four iridoid glycosides, one lignan glycoside and one monoterpenoid were isolated from the 95% ethanol extract from the stem of C. tubulosa and identified as adoxosidic acid(I), 8-epiloganic acid(II), geniposidic acid (III), mussaenosidic acid(IV), (+)-syringaresinol-O-beta-D-gluco pyranoside(V) and 8-hydroxygeraniol(VI). CONCLUSION: Compounds I and VI were isolated from the genus of Cistanche for the first time. Compounds III, IV and V were isolated from this plant for the first time.

Carboxylic Acids↗

PubMed2000

[The effect of injuries on Fn synthesized by FBs and its implication in wound timing].

cFn synthesized by FBs around the wound was detected by immunochemistry in vitro. Using the method of ELISA, The concentration of cFn in the culture media was observed. The concentration of cFn had no change within 30 minutes after injury, but started to increase after 1 hour of the injury and kept this trend within next five hours after injury. By static analysis, it can be obtained that the concentration of cFn in culture media is time-dependent after injury.

Cells, Cultured↗

PubMed2000

[An experimental study on the effect of positional asphyxia on cardiac and pulmonary functions].

The purpose of the study is to explore the effect of positional asphyxia on cardiac and pulmonary functions and its role in causing death. respiration, pulmonary artery pressure and cardiac output were measured by inserting the swan-ganz into the pulmonary artery from the femoral vein. Results showed that: (1) the respiration was stable before hanging, getting faster during hanging, and becoming irregular at the terminal stage of hanging; (2) the pulmonary artery pressure increased significantly during and at the terminal stage of hanging as compared with that before hanging; (3) the cardiac output was stable before and during hanging, but decreased significantly at the terminal stage of hanging. It is concluded that hanging may cause respiratory imbalance and hypoxia, resulting in cardiac and pulmonary dysfunction. The death caused by hanging belongs to respiratory death, the characteristic of which is primary respiratory arrest followed by secondary cardiac arrest.

Airway Obstruction↗

PubMed2000

[Expression of bcl-2 and Bax protein in the failing human heart--an inhibitor or accelerator of apoptosis?].

In general, myocyte death in myocardial infarctions (MI) is attributed to necrosis, but recently the involvement of apoptosis has been suggested. Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. The expression of two proto-oncogenes influence apoptosis. Myocytes with positive bcl-2 immunoreactivity were seen in the heart of acute MI, localized only in the salvaged areas surrounding the infarcted tissues. Myocytes with overexpressed positive Bax immunoreactivity were observed in the salvaged areas of old MI.

Apoptosis↗

PubMed2000

[Circadian rhythm changes of the levels of endogenous insulin in growing rat condylar cartilage after functional mandibular protrusion].

OBJECTIVE: In order to determine which time of the day is best to wear functional appliances in clinic, the author investigates the circadian rhythm of the level of endogenous Insulin in growing rat condylar cartilages and the changes after functional mandibular protrusion in daytime (8:00-20:00) or nighttime (20:00-8:00). METHODS: 72 4-week-old SD rats were divided equally and randomly into experimental and control groups, and the rats in experimental groups were put on the functional appliance in daytime (8:00-20:00) or nighttime (20:00-8:00). After 7 days, all rats were sacrificed at 0:00, 4:00, 8:00, 12:00, 16:00, 20:00 in a day. Radioimmunoassay methods were used to detect the levels of endogenous insulin in growing rat condylar cartilages. RESULTS: 1. The levels of endogenous insulin in the growing rat condylar cartilage displayed a significant circadian rhythm. The acrophase was about 12:13. 2. The circadian rhythm still existed after the rats had been put on the functional appliance. Both mesor and amplitude were significantly higher in the experimental groups than in the control group 3. The levels (both mesor and amplitude) of endogenous insulin in the condylar cartilage were significantly higher in the daytime-forced group than in the nighttime-forced group. CONCLUSION: 1. The growth and remodeling of the condylar cartilage in the growing rats shows significant circadian rhythm. The most active period of chordrocyte proliferation may occur during the daytime. 2. The circadian rhythm still exists after the rats have been put on the functional appliances. 3. Compared with nighttime appliance wearing, daytime appliance wearing may be more conductive to cell proliferation, so it may be more effective to stimulate the growth and remodeling of condylar cartilage in the growing rat. 4. Related to human beings, these data suggest that the best period for patients to wear the functional appliances might be from 20:00 pm to 8:00 am of the next day.

Animals↗

PubMed2000

[The diel rhythm of PGE2 in blood of the growing rat after retractive force on mandible].

OBJECTIVE: To study whether the orthopedic therapy will affect the rat's metabolism, the author investigates the diel rhythm of PGE2 in blood of the growing rats before and after retractive force on mandible. METHODS: 72 rats which were 4 weeks old and about 90 g, were divided equally and randomly into three groups: the contrast group were not exerted force, the daytime-forced group were exerted force from 8:00 am to 20:00 pm, the nighttime-forced group were exerted force from 20:00 pm to 8:00 am of the next morning. The backwards force imposed on the rats were exerted through the center of the mandibular condyle and was about 40 g(0.4 N). The period of experimentation was 7 days. In the 8th day, every 4 rats from each of the group were killed respectively at 0:00, 4:00, 8:00, 12:00, 16:00 and 20:00 to collect 3 ml blood. Then radioimmunoassay methods were used to measure the concentration of PGE2 in the blood. RESULTS: In natural state, there was a diel rhythm in the concentration of PGE2 in rats' blood and the diel rhythm was related to that of endogenous PGE2 in condyle; After imposed orthopedic force to restrain mandibular growth, the normal diel rhythm of PGE2 in blood disappeared. There was no significant difference in the time-concentration curves between the contrast group and the daytime-forced group (P > 0.05), but the difference between the contrast group and the nighttime-forced group was obvious (P < 0.05) and the mesor of the nighttime-forced group was greatly decreased. CONCLUSION: The concentration of PGE2 in rats' blood will not be affected by the orthopedic force in daytime, in nighttime. For this reason, not only the therapeutic effect but also the effect on the body's metabolism should be considerd in clinical therapy, and further researches should be carried out on whether the local orthopedic force would influence the metabolism of the whole body.

Animals↗

PubMed2000

[Circadian rhythm changes of the levels of endogenous insulin in growing rat's blood after functional mandibular protrution].

OBJECTIVE: In order to determine whether the metabolism of the body can be influenced by local functional orthopedic treatments and the relationship between the proliferation and translation of condyle and the metabolism of the body, the author investigates the circadian rhythm of the levels of endogenous insulin (Ins) in growing rats' blood and the changes after functional mandibular protrusion in daytime (8:00-20:00) or nighttime (20:00-8:00). METHODS: 72 4-week-old SD rats were divided equally and randomly into experimental and control groups, and the rats in experimental groups were put on the functional appliances in daytime (8:00-20:00) or nighttime (20:00-8:00). After 7 days, all rats were sacrificed at 0:00, 4:00, 8:00, 12:00, 16:00, 20:00 in a day. Radioimmunoassay methods wore used to detect the levels of endogenous insulin in growing rats' blood in every four hours of a day. RESULTS: 1. The growing rats' blood displayed a significant circadian rhythm in the levels of endogenous insulin, the acrophase was about 13:02. 2. The circadian rhythm still existed after used functional appliance. No significant changes (both mesors and amplitudes) had been observed in the experimental groups comparing with the control groups. 3. The circadian rhythm of insulin in blood concerned with that of endogenous insulin in condyle. CONCLUSION: 1. The metabolism of the body can not be influenced by local functional orthopedic treatments. 2. The proliferation and translation of condyle concern with the metabolism of the body.

Animals↗

PubMed2000

[Study on the characteristics and applications of a new hydrophobic interaction chromatographic packing using chitosan as support].

Based on chitosan, by using valeraldehyd as ligand, a new hydrophobic interaction chromatographic (HIC) packing material was prepared by an improved method. The effects of salt concentration, temperature, pH on the adsorption of bovine serum albumin(BSA) were investigated. The results showed that the adsorption behavior of protein by packing material is in agree with the theory of hydrophobic interaction. The alpha-amylase could be separated by HIC with high recovery of enzymatic activity.

Chitin↗