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Biomedical subjects

Y Dai

Publications and source records attributed to Y Dai.

At least 127 records · Page 7Linked to original sources
PubMed1999

[HBxAg enhanced p53 protein accumulation in hepatoma cells].

OBJECTIVE: In order to determine the interaction between HBxAg and p53 protein and its role in hepatocarcinogenesis. METHODS: Cotransfection was performed using reporter gene, chloramphenical acetyltransferase (CAT), p53 and HBVx gene, and dexamethasone inducible HBx plasmid pMAMHBx was constructed for the experiment. Human hepatoma cell line Hep3B was used as the target cell. The activity of HBxAg and p53 was detected by CAT assay and immunohistochemical staining after transient transfection. RESULTS: HBxAg could increase the accumulation of p53 protein in cells and enhance CAT expression. Immunohistochemical staining showed that p53 protein bound to HBxAg in the cytoplasm and formed a complex causing a partial block of the process of p53 during passing through the nuclear membrane from the cytoplasm. CONCLUSION: Data strongly suggested that HBxAg is capable of binding p53 and forms a protein-protein complex which might reduce or inactivate p53's antiproliferative activity and plays an important role in the pathogenesis of HBV-associated hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed1999

[Determination of resveratrol in grape wine by high performance liquid chromatography].

Resveratrol is a microactive factor for preventing human cancer. A reversed phase high performance liquid chromatographic method for the determination of resveratrol in grape wine was developed. Samples were extrated by ethyl acetate and washed with 3% NaHCO3; after dehydrated with Na2SO4 and dried in vacunm at 40 degrees C, dissovled in acetonitrile. The conditions of HPLC analysis were as follows: the maximum absorptions of trans-resveratrol and cis-resveratrol were at 306 nm and 280 nm respectively. Separation was achieved by the use of mu-Bondapak C18 column (3.9 mm x 300 mm). The mobile phase was V(acetonitrile):V(water) = 40:60. The retention times of trans- and cis-resveratrol were 7.7 min and 8.9 min respectively. The recovery rates were 90.0%-97.8% and the CV was 3.3%. Detection limit was 10 micrograms/L. Eleven kinds of red and white grape wine made in China were detected. All of them contained resveratrol, but the quantity, from 10.0 to 920.0 micrograms/L, were quite different.

Anticarcinogenic Agents↗
PubMed1999

[Bio-safety testing for retroviral vector as gene therapy delivery system].

OBJECTIVE: To generate a bio-safety testing system including the testing of sterility, mycoplasma and replication-competent retroviruses(RCR) in the study of gene therapy anti-hepatitis B virus by intracellular immunization. METHODS: Mycoplasma was detected by polymerase chain reaction. S+/L- assay, NIH3T3 amplification and rescue assay of neo gene were performed to determine RCR. RESULTS: The results showed that all of the packaging cell lines were negative for aerobic, anaerobic bacteria and fungi. One of the packaging cell lines was positive for mycoplasma. No RCR was detected in all of the packaging cell lines. CONCLUSIONS: The results suggested that the methods using in present report are stable and sensitive, it is very useful for bio-safety testing of gene therapy in clinical trials.

3T3 Cells↗
PubMed1998

Transgenic mouse model for skin malignant melanoma.

We report here on a novel metallothionein-I (MT)/ret transgenic mouse line in which skin melanosis, benign melanocytic tumor and malignant melanoma metastasizing to distant organs develop stepwise. The process of tumor development and its malignant transformation in this line may resemble that of the human giant congenital melanocytic nevus that is present at birth and that frequently gives rise to malignant melanoma during aging. We observed an increase in the expression level and activity of the ret transgene during the disease progression. That increase in transgene expression accompanied an activation of mitogen-activated protein kinases (MAPKs) and c-Jun as well as matrix metalloproteinases. These results suggest that progressive dysregulation of the expression level of the ret transgene might play a crucial role in the malignant transformation of melanocytic tumors developed in the MT/ret transgenic mouse line.

Animals↗
PubMed1998

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for polymer analysis: solvent effect in sample preparation.

The success of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry for the characterization of polymer structures and for the determination of average molecular weights and distributions depends on the use of a proper sample/matrix preparation protocol. This work examines the effect of solvents, particularly solvent mixtures, used to prepare polymer, matrix, and cationization reagent solutions, on MALDI analysis. It is shown that the use of solvent mixtures consisting of polymer solvent does not have a significant effect on the molecular weight determination of polystyrene 7000 and poly(methyl methacrylate) 3750. However, solvent mixtures containing a polymer nonsolvent can affect the signal reproducibility and cause errors in average weight measurement. This solvent effect was further investigated by using confocal laser fluorescence microscopy in conjunction with the use of a fluorescein-labeled polystyrene. It is demonstrated that sample morphology and polymer distribution on the probe can be greatly influenced by the type of solvents used. For sample preparation in MALDI analysis of polymers, it is important to select a solvent system that will allow matrix crystallization to take place prior to polymer precipitation. The use of an excess amount of any polymer nonsolvent should be avoided.

Algorithms↗
PubMed1998

Financing changes of schistosomiasis control programmes in China 1980-1995: a case study in Songzi county.

To assess the financing changes of schistosomiasis control programmes in China and estimate the impact of these changes on patients' treatment-seeking behaviour and control of schistosomiasis, a survey was conducted in five schistosomiasis-endemic areas of the lake regions, Hubei province, in 1996. This paper reports financing changes and their impact on the incidence and prevalence of schistosomiasis from one of the five areas as a case study. By examining the surveillance and financial data from 1980 to 1995, and through focus group discussions we found that the schistosomiasis control programmes in People's Republic of China have gone through dramatic financing changes from 1980 to 1995, when the transitions of China's social, economic, and political systems happened. The proportions of funding to schistosomiasis control programmes from high level governmental agencies, county budgets, and services revenue changed from 60%, 23%, and 17%, respectively, in 1980-1987 to 0.7%, 22.3%, and 72% in 1995. The percentages of expenditure of schistosomiasis control activities, salaries and bonuses, and other activities unrelated to schistosomiasis control, were 53.5%, 14.4, and 17.2% in 1980. These percentages changed to 7.7%, 33.3%, and 53.3%, respectively, in 1995. The preponderant role of the state in organizing, financing, and delivery of the services was replaced with the new system which is more influenced by the market economy. The incidence and the prevalence of schistosomiasis in the study area have increased year by year from 1980 to 1990, although there has been a tendency to decrease after 1991 but not to the low pre1980 levels. The collapse of the community-based medical system in rural areas and the dramatic financing changes of schistosomiasis control programmes have created major difficulties for schistosomiasis control in China.

China↗
PubMed1998

The implication of anthracosis in the development of pulmonary adenocarcinoma.

The relationship between anthracosis, which is the deposition of black dust matter in the lung parenchyma, and the development of pulmonary adenocarcinoma has not been fully characterized. In order to clarify whether background black dust matter deposition could be implicated in the development of pulmonary adenocarcinoma, we measured the level of anthracosis at autopsy in 47 patients who had died of pulmonary adenocarcinoma. Both lungs of all 47 cadavers were examined. Twenty-micrometer sections were cut from formalin-fixed, paraffin-embedded blocks of the largest cut surface of each lung. Black dust matter was extracted from the sections and blotted onto a nitrocellulose membrane. The density of the blotted black dust matter was then analyzed using an imaging densitometer. There were no significant differences in the density of black dust matter deposition between lungs affected by pulmonary adenocarcinoma and control lungs. However, well differentiated adenocarcinomas tended to develop more frequently than poorly differentiated ones in lungs showing less deposition. We found a very strong correlation between the degree of black dust matter deposition and smoking history. Patients with severe anthracosis tended to have a poorer prognosis than those with mild anthracosis.

Adenocarcinoma↗
PubMed1998

The human placenta and fetal membranes express the corticotropin-releasing hormone receptor 1alpha (CRH-1alpha) and the CRH-C variant receptor.

Placentally derived CRH plays a major role in the mechanisms controlling human pregnancy and parturition. It has been suggested that there is a CRH placental clock that is active from the early stages of pregnancy and determines the length of gestation and the timing of parturition. CRH can influence human reproductive tissue function via specific CRH receptors. Two distinct CRH receptors have been cloned (R1 and R2) that share 70% homology at the amino acid level and exist as two alternatively spliced forms (alpha and beta). In this study we investigated the presence of CRH receptor subtypes in human fetal membranes derived from spontaneous rupture and placental biopsies at term. Using RT-PCR, we identified the full length of the CRH-R1alpha subtype in placental and fetal membranes. In both tissues we also identified a spliced variant of the CRH receptor (CRH-Rc). We were unable to detect any CRH-R2 messenger ribonucleic acid in any of the biopsies. Fluorescent in situ hybridization and immunofluorescence in both tissues demonstrated that syncytiotrophoblast cells and amniotic epithelium are the major cell types expressing CRH-1alpha and CRH-Rc receptor messenger ribonucleic acid. Further studies are necessary to give a better insight into the role of CRH and its receptors in these tissues.

Extraembryonic Membranes↗
PubMed1998

Human corticotropin-releasing hormone receptor: differences in subtype expression between pregnant and nonpregnant myometria.

There is increasing evidence that CRH, which is the principal neuroregulator of the hypothalamic-pituitary-adrenocortical axis, is also involved in the mechanism of human labor. The human myometrium has been shown to express several high affinity CRH receptors, although the identities of the CRH receptor subtypes have yet to be identified. To investigate further the expression of the CRH receptor in human myometrium, we used RT-PCR, fluorescent in situ hybridization and immunofluorescence to identify and localize the four subtypes, 1 alpha, 1 beta, 2 alpha, and the variant C, of the CRH receptor. Interestingly, the CRH receptor subtypes in myometrium exhibit differential expression patterns; in human pregnant myometrium at term all four receptor-subtypes were expressed, whereas only the 1 alpha- and 1 beta-receptor subtypes were found in the nonpregnant myometrium. This would suggest that CRH, acting via different receptor subtypes, is able to exert different actions on the myometrium in the pregnant state compared to the nonpregnant state. Furthermore, in the pregnant human uterus, CRH receptors were localized in both smooth muscle and fibroblasts. These findings suggest that CRH receptor expression plays an important modulatory role in myometrial and possibly in cervical function.

Case-Control Studies↗
PubMed1998

Studies on Kochiae Fructus. V. Antipruritic effects of oleanolic acid glycosides and the structure-requirement.

We examined the antipruritic effects of various oleanolic acid glycosides from natural medicines such as Kochiae Fructus (the fruit of Kochia scoparia SCHRAD.) and Momordicae Radix (the roots of Momordica cochinchinensis SPRENG.) using a compound 48/80-induced pruritic model in mice. Oleanolic acid 3-O-monodesmosides showed an antipruritic effect, while oleanolic acid 3,28-O-bisdesmosides and their common sapogenol oleanolic acid lacked the activity. This evidence indicated that the 3-O-glycoside moiety and the 28-carboxyl group in oleanolic acid glycosides were essential for exhibiting the antipruritic effect. Furthermore, it was found that the 3-O-glucuronides showed more potent activity than the corresponding 3-O-glucosides.

Animals↗
PubMed1998

[Analysis of surface markers of long-term cultured human umbilical cord blood hemopoietic cells].

OBJECTIVE: To explore the optimal time for in vitro expansion and transplantation of umbilical cord blood hemopoietic cells. METHODS: Hemopoietic cells from human umbilical cord blood were cultured with SCF, rIL-3, rIL-6 and rIL-1 beta in a long term culture system and changes of cellular surface markers were observed. RESULTS: CD3+ and CD20+ lymphocytes increased at the 7th day, and gradually decreased to the lowest level after the 14th day. CD34 positive cells increased after the 7th day, and reached the highest level at the 14th day, then decreased gradually but maintained at a higher level than that at the 7th day. CD33 positive cells increased at the 7th day, and reached the highest level from the 14th to the 21st day, then decreased after the 28th day. CD42b positive cells began to increase at the 21st day, reached the peak at the 28th day, and still maintained higher level at the 35th day. HLA-DR positive cells increased from the 14th to the 21st day. CONCLUSION: The culture system containing the four growth factors is able to expand hemopoietic cells from human umbilical cord blood and keeps them intact. From the 14th to the 21st day, the number of hemopoietic cells reached the highest level, and is suitable for transplantation.

Antigens, CD20↗
PubMed1998

[Detecting coronary artery disease with dobutamine 99mTc-MIBI myocardial perfusion tomography].

OBJECTIVE: To assess the safety and accuracy of dobutamine stress 99mTc-MIBI perfusion tomography (DST) for detecting coronary artery disease(CAD). METHODS: Seventy nine patients with suspected CAD without previous myocardial infarction underwent DST. Forty eight of the 79 patients had coronary angiography and CAD was defined as greater than 50% reduction in diameter. RESULTS: Seventeen of 20 patients with CAD demonstrated perfusion abnormalities by DST (sensitivity 85%), 20 of 24 with normal or non-significant stenosed coronary arteries had normal scan (specificity 83.3%). All 4 patients with coronary ectasia showed abnormalities by DST. Fifty seven percent of the patients experienced some discomfort, but no serious side effects occurred. CONCLUSIONS: It shows that DST is a safe and accurate alternative to exercise stress perfusion study for detecting CAD in patients unable to perform exercise testing.

Adult↗
PubMed1998

Effect of +Gz on plasma levels of calcitonin gene related peptide, endothelin and renal function in pilots.

The effect of positive acceleration on plasma levels of calcitonin gene related peptide (CGRP), and endothelin as well as renal function in pilots were observed in this study. 20 pilots were exposed to +2.5 Gz 10 s and +3.0 Gz 10 s with an interval of 5 min without anti-G suits. Samples of plasma and serum were taken 2Omin before and after exposure. Plasma levels of CGRP and endothelin after the exposure were significantly increased (P<0.01), but alkaline phosphatase(AKP), blood levels of beta 2-microglobulin(beta 2-MG), Ca2+ in serum showed no significant change (P>0.05) as compared with those before exposure. There was a correlation between CGRP and endothlin (r=0.772, P<0.01). It is concluded that positive acceleration(+2.5, +3.0Gz) could increase plasma levels of CGRP and endothlin but did not affect renal function.

Acceleration↗
PubMed1998

[Changes of plasma endocrine hormone in pilots under Coriolis acceleration].

Plasma endocrine hormones were studied in both 24 motion sickness (orthostatic intolerance) and healthy pilots. Coriolis acceleration of 3.75, 5.00 and 6.25 pi 2 cm/s2 were given with intervals of 3-4 min AT-II, insulin, cortisol, Aldosterone and gastrin were determined by radioimmunoassay. It was found that aldosterone, AT-II, gastrin increased with increase of coriolis acceleration in all pilots. (P < 0.05), but cortisol and insulin only increased in healthy pilots (P < 0.05). It suggests excitation of the autonomic nervous system might be insufficient in orthostatic intolerant pilots and that determination of endocrine hormones may be useful in the evaluation of autonomic nervous activities.

Acceleration↗