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Biomedical subjects

F Ren

Publications and source records attributed to F Ren.

36 records · Page 2Linked to original sources
PubMed1998

[Studies on hepatitis B virus infection in blood donors with positive anti-HBc and negative HBsAg].

OBJECTIVE: To study if it is necessary to screen for core antibody against hepatitis B (anti-HBc) to prevent post-transfusion hepatitis B and what is its criteria for screening. METHODS: Relationship between the titer of anti-HBc and HBV DNA in blood from qualified donors by routine testing was conducted. HBV DNA was detected in 297 units of blood with anti-HBc at various titers by immuno-nested polymerase chain reaction (RT-PCR). RESULTS: HBV DNA was detected in one of four units of blood with positive anti-HBc at a dilution of equal to or greater than 1:128, and no HBV DNA was detected in other 75 units of blood with a dilution of anti-HBc less than 1:128. There was significant relationship between HBV DNA and the titer of anti-HBc. No HBV DNA was detected in 218 units of blood with both positive anti-HBc and anti-HBs and in 50 units with negative anti-HBc. Detection rate of HBV DNA in blood with positive anti-HBc was only 0.34% (1/297). CONCLUSION: Blood containing higher titer of single anti-HBc may be infectious. It is suggested that sensitivity of the reagents for detecting HBsAg currently used (1 ng/ml) be improved with the limited budget.

Adult↗
PubMed1998

The application of model-based complexity inference method to molecular evolution analysis.

In this study, a new method based on the concept of complexity in inductive inference is proposed for reconstructing molecular phylogenetic tree. This method describes the complexity of molecular phylogenetic tree by three terms, which are related to tree topology, the branch lengths and fitness between the model and data measured by likelihood function. The computer simulation is used to investigate the efficiency of this method. The results suggest that this method is superior to the traditional methods because it avoids excess-complexity in the tree model estimation available from DNA sequence.

Base Sequence↗
PubMed1998

[Relationship between change of erythrocyte membrane lipid composition and pregnancy induced hypertension].

OBJECTIVE: To study the cause of decreased erythrocyte deformability and its relation to pregnancy induced hypertension (PIH). METHODS: The cholesterol and phospholipid content of erythrocyte membrane in 24 non-pregnant healthy women, 22 normotensive pregnant women and 36 cases with PIH were determined using automatic biochemical analysor, Gas chromatography and modified colorimetric method. RESULTS: The cholesterol content and the cholesterol/phospholipid (C/P) ratio of the erythrocyte membrane were obviously higher in the group with moderate or severe PIH than that in the nonmotensive pregnancies (P < 0.01). There was no significant difference between mild PIH group and the normotensive pregnant group (P > 0.05). CONCLUSION: The increase of cholesterol content and C/P ratio in the erythrocyte membrane might be involved in the pathophysiology of PIH. The alteration of cholesterol content in the erythrocyte membrane probaby reflected the disturbance of serum lipid metabolism.

Adult↗
PubMed1997

Inference of molecular phylogenetic tree based on minimum model-based complexity method.

In this study, starting with a newly introduced concept of data complexity ("empirical data complexity"), we specify the concept of complexity more concretely in relation to mathematical modeling and introduce "model-based complexity (MBC)". Inductive inference based on the minimum model-based complexity method is then applied to the reconstruction of molecular evolutionary tree from DNA sequences. We find that minimum MBC method has good asymptotic property when DNA sequence lengths approach to infinite and compensates the bias of maximum likelihood method due to the difference of tree topology complexity. The efficiency of minimum MBC method for reconstruction of molecular tree is studied by computer simulation, and results suggest that this method is superior to the traditional maximum likelihood method or its modification by Akaike's AIC.

Animals↗
PubMed1995

Construction of molecular evolutionary phylogenetic trees from DNA sequences based on minimum complexity principle.

Ever since the discovery of a molecular clock, many methods have been developed to reconstruct the molecular evolutionary phylogenetic trees. In this paper, we deal with the problem from the viewpoint of an inductive inference and apply Rissanen's minimum description length principle to extract the minimum complexity phylogenetic tree. Our method describes the complexity of the molecular phylogenetic tree by three terms which are related to the tree topology, the sum of the branch lengths and the difference between the model and the data measured by logarithmic likelihood. Five mitochondrial DNA sequences, from the human, the common chimpanzee, the pygmy chimpanzee, the gorilla and the orangutan, are used for investigating the validity of this method. It is suggested that this method might be superior to the traditional method in that it still shows good accuracy even near the root of phylogenetic trees.

Algorithms↗
PubMed1995

[24-hour esophageal pH monitoring for suspected esophageal originated chest pain].

Thirty patients with suspected esophageal originated chest pain were studied by 24 h esophageal pH monitoring. All of them complained of chest pain, heart burn, acid reflux or dysphagia. The result showed abnormal pH in 26 patients (86.7%). Sixteen of them had pH abnormalities in both day and night, whereas 8 had only abnormal day pH, and 2 pH out of the normal limits at night. Chest pain episode was correlated with the abnormalities in 18 cases (60%). Four patients with coronary heart disease showed simultaneous gastro-esophageal reflux originated chest pain; the positive correlation was obtained. Their diagnosis of cardiac chest pain was doubtful. We suggested that 24h pH monitoring was a significant method to determine the cause of chest pain.

Adolescent↗
PubMed1994

Identification of a 12.5-kD protein from caudate-putamen nucleus as a dopaminergic neuronotrophic factor.

The effect of the extract from caudate-putamen nucleus of newborn rats (CPe) on the dopaminergic (DA) neurons has been studied. An MTT colorimetric microassay measuring optical densities for the growth of DA neuron cultures reveals a significant increase in growth for cultures with CPe as compared to those without CPe (p < 0.05). Rhodamine retrograde-prelabelled DA neurons were cultured on a Phastgel containing all the electrophoretically separated protein bands from CPe, and able to fish out from it their own trophic factor, a 12.5-kD protein band. The survived neurons at the 12.5-kD protein band were immunostained positive with anti-dopamine antibody. Co-culturing the 12.5 kD-containing gel strip with explants from substantia nigra at a close distance for a week revealed anti-dopamine immunopositive neurites outgrowing from the explants only towards the 12.5-kD gel strip. These results indicate that a 12.5-kD protein from the CPe is capable of maintaining the survival of DA neurons of the substantia nigra and promoting their neurite outgrowth.

Animals↗
PubMed1993

[Growth inhibitory action of RGNTF-McAb on human retinoblastoma cell line Y-79].

The monoclonal antibody against the retinal ganglion neuronotrophic factor (RGNTF-McAb) was used in immunostaining of the Western blotting membrane separated from extract of human retinoblastoma cell line Y-79 to find that the latter contained a 30KD protein which was immunologically similar to the RGNTF secreted from the tectum of rat. The effect of different concentrations of RGNTF-McAb on the growth of Rb cells in cultures of different seeding concentrations was studied, revealing that the growth inhibitory action of RGNTF-McAb increased with increasing concentrations, up to 67% inhibition. Morphologically the growth and division of Rb cells were significantly inhibited as compared to the controls. The RGNTF-anti-idiotypic antibody was used for the localization of the RGNTF receptor, which the immunoreactive positive staining indicated to be on the surface of Rb cell membrane. The RGNTF-McAb could thus neutralize the RGNTF and inhibit growth of the Rb cells. These findings support the application of RGNTF-McAb to the treatment of retinoblastoma.

Antibodies, Anti-Idiotypic↗
PubMed1993

[Anti-retinoblastoma reaction developed in vivo through immunization of retinal ganglion neuronotrophic factor].

Isolated retinal ganglion neuronotrophic factor (RGNTF) was used as an antigen to immunize Group A Balb/c mice intraperitoneally prior to the inoculation into the anterior chamber of eye with human retinoblastomal cell line Y-79 (Rb). In Group B mice, Rb cells were inoculated into the eyes before RGNTF immunization. In Group C mice, empty gel without RGNTF was used in immunization 10 days after the Rb inoculation, to serve as a control. The results revealed that the inhibitory rate of Rb tumor development in Group A was 65% (13/20); in Group B only 10% (2/20); and in Group C 0% (0/20). The T-test for difference in the inhibitory rate between Group A and B was statistically significant (T > 2.58; P < 0.01). Sera were collected from these mice and their content of the anti-RGNTF antibody was quantified by ELISA method. The results showed that the anti-RGNTF antibody titer in Group A antisera at 1:600 dilution was measured with an average optical density of 0.156 +/- 0.015; that in Group B 0.103 +/- 0.016; and that in Group C only 0.048 +/- 0.018. Those of controls for normal mouse serum and culture medium were 0.050 +/- 0.008 and 0.043 +/- 0.014, respectively. The t test for difference in the antibody titer measurements between Group A and B was statistically significant (t > t0.05; p < 0.05). Therefore, the above results indicated that active immunization of RGNTF can enhance the specific immunity against the development of retinoblastomal tumor in Balb/c mice, which may have clinical significance in treating human retinoblastoma.

Animals↗
PubMed1993

Changes in rat retinal ganglion neuronotrophic factor and its mRNA during postnatal development.

The monoclonal antibody specific to the retinal ganglion neuronotrophic factor (RGNTF) was used to localize and quantify the presence and amount of RGNTF during the postnatal development of the visual system in the rat. The results showed that in the 0-1-day age group, neurons at the superficial layers and deep part of superior colliculus, and as well as retinal ganglion cells were strongly stained with their RGNTF contents quantified to be 88%, 100% and 100%, respectively. In the 5-6-day age group, RGNTF contents were significantly reduced to merely 50%, 30% and 80%, respectively. The RGNTF contents reduced further to 0% as age increased to 2 years old. A 32P-DNA probe specific to the first 7 amino acid sequence of RGNTF at its N-terminal end was synthesized and used for in situ hybridization studies. The results revealed that strong hybridized signals (i.e. mRNA of RGNTF) were localized in the same neurons in the superficial layers and deep part of the superior colliculus only in the 0-1-day age group, and that no signals were found in retinae of all postnatal age groups. The significant reduction of RGNTF may be related to the RGC death during postnatal development. Neurons at the superficial layers and deep part of the superior colliculus are the sources of RGNTF for RGCs in the postnatal retina.

Age Factors↗
PubMed1992

[Immunotherapy of human retinoblastoma with RGNTF-monoclonal antibody using nude mice as model].

Retinoblastoma in nude mice as an animal model was developed by injecting cultured human retinoblastoma cell line(Rb) Y79 into the anterior chamber of eyeball. It was treated by direct injection of RGNTF-McAb into the Rb tumor. Ten out of 30 eyeballs with Rb inoculation did not develop tumor (32% inhibition) if Rb cell suspension was mixed with the RGNTF-McAb before injection; whereas in the control, all 40 but 3 eyeballs developed tumor (7%) when Rb cell suspension alone had been injected. This 32% of inhibition of Rb tumor formation by RGNTF-McAb was very significant (T > 2.58, P < 0.01). The results of immunotherapy of 46 eyeballs with Rb tumor developed 10 days after inoculation by RGNTF-McAb for 2 months revealed that the proportion of grade III-IV tumors before and after therapy reduced from 53% to 26% and that of grade I-II tumors increased from 47% to 74%. Feulgen DNA staining of tumor sections after therapy revealed that the average DNA contents in Rb cells decreased significantly (P < 0.01) from 16.2 +/- 2.6 in grade III-IV to 5.3 +/- 1.2 in grade I-II compared to that of the untreated control 18.8 +/- 3.2. Numerous white cells infiltrating the Rb tumor, hyperplasia of fibrous tissues, and no spreading and metastasis of the tumor tissue were observed in the treated eyeballs; whereas Rb tumor was spreading to the optic nerve and superior colliculus in the untreated eyeballs. Therefore, the RGNTF-McAb can not only inhibit the growth of Rb cells but also limit their spreading and metastasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Monoclonal antibody against human primary hepatocellular carcinoma and immunocytochemical localization of the corresponding antigen].

A monoclonal antibody HAB5 was raised against human hepatocellular carcinoma. The reactivity of HAB5 was determined immuno-histologically on paraffin sections by ABC technique. Positive reaction was seen in 88% of 50 cases of hepatoma examined, including 2 cases of spindle-cell hepatoma. Positive reaction was also seen in 16% squamous-cell carcinoma and 25% transitional cell carcinoma. The monoclonal antibody did not react with metastatic adenocarcinoma of liver in 7 cases. The antigen to which HAB5 directed was a membrane glycoprotein with a molecular weight of 68 KDa.

Animals↗
PubMed1991

[Characteristics and inhibitory action of monoclonal and polyclonal antibodies against the retinal ganglion neuronotrophic factor (RGNTF)].

We have immunized Balb/c mice and rabbits with a minute quantity of a 30 kD neuronotrophic factor which was isolated from the extract of newborn rat tectum (Te) by Phast System gel electrophoresis. Splenic cells from the immunized mice were hybridized with NS-1 mouse myeloma cells. Three clones were selected from 576 wells of hybridomas and were capable of secreting monoclonal antibodies specific to the retinal ganglion neuronotrophic factor (RGNTF-MAbs), namely A1, D3 and E8. Subtyping of the three monoclonal antibodies revealed that A1 and D3 are IgG3 and E8 is IgM. They maintained secreting antibodies even after six months of culturing in vitro. In order to determine the specificities of these antibodies, we have used their ascites fluids containing antibodies at a different dilutions to study their effects on the survival of retinal ganglion cells in vitro. The results indicated that at the dilution ranges of 1:250 to 2000, all three monoclonal antibodies exhibited inhibition on the survival of retinal ganglion cells and the inhibition increased with increases in antibody concentrations; especially at a dilution of 1:250, the E8 monoclonal antibody reaching 70% inhibition and A1 and D3 reaching 66% and 62% inhibition, respectively. Polyclonal antibodies from rabbits exhibited similar but weaker results of inhibition. We can conclude that the monoclonal and polyclonal antibodies can specifically inhibit the activity of the 30 kD retinal ganglion neuronotrophic factor.

Animals↗
PubMed1990

[Amino acid analysis of the main organs during different growing periods of panax ginseng C.A. Mey].

Studies on different growing periods of Panax ginseng, its ages and the variation regularities of amino acids in its main organs are reported. The test has shown that it contains seventeen amino acids. The total amount of amino acids reaches its peak point during the sprouting period (in April), next to it is the withering period (in September), flowering and fruiting periods being the lowest (in June). The amount of these acids in the main root is higher than that in the fibrous root, the lowest being in the lateral root. Five-year-old Panax ginseng features the highest amount.

Amino Acids↗
PubMedDate not supplied

Performance of AlGaN/GaN high electron mobility transistors at nanoscale gate lengths.

The DC and RF performance of AlGaN/GaN high electron mobility transistors with nanoscale gate lengths is presented. The layer structures were grown by either metal organic chemical vapor deposition or rf plasma-assisted molecular beam epitaxy. Excellent scaling properties were observed as a function of both gate length and width and confirm that these devices are well suited to both high speed switching and power microwave applications.

Aluminum↗