Biomedical subjects

Z Feng

Publications and source records attributed to Z Feng.

At least 145 records · Page 8Linked to original sources

PubMed1998

Multifocal accumulation of p53 protein in esophageal carcinoma: evidence for field cancerization.

A systematic characterization of the cancerization field of esophageal carcinoma based on p53 protein accumulation has not been reported previously. The present report presents such a study based on 50 specimens of esophageal squamous-cell carcinoma from northern China. To gain insight into the etiology of this disease among the 50 subjects, DNA was analyzed for a polymorphism of the aldehyde dehydrogenase-2 (ALDH2) gene, which has been associated with increased risk for esophageal cancer among alcohol-consuming patients in Japan. However, the frequency of this polymorphism among our subjects, 30% (15/50), was within published control frequencies for this allele, suggesting that this allele may not play a role in the etiology of esophageal cancer in this northern Chinese population. Immuno-histochemical staining showed that 66% of the tumors were p53+. Of 420 pieces near or adjacent to p53+ tumors, p53+ cells were present among 64% of basal-cell hyperplasia (BCH), 70% of dysplasia (DYS) and 88% of carcinoma in situ (CIS). Of 216 pieces near or adjacent to p53- tumors, p53+ frequencies were 25% of BCH, 25% of DYS and 0% of CIS. The proportion of BCH cells that were p53+ decreased at increasing distance from the tumor (p = 0.006). The sporadic distribution of p53+ cells and the distribution and frequency of p53+ precursor lesions support the view that accumulation of p53 protein is multifocal and occurs in precursor lesions in early stages of esophageal carcinogenesis.

Adult↗

PubMed1998

Apoptosis during castration-induced regression of the prostate is Fos dependent.

Apoptotic cell death was shown to be accompanied or preceded by an elevated expression of the c-fos protooncogene and DNA binding activity of transcription factor AP-1. We used Fos-deficient mice to study the role of c-Fos during programmed cell death in the prostate. In normal mice apoptosis is induced in the prostate within 2-4 days after castration. Histological features of reduced secretory activity and morphological signs of programmed cell death become obvious. No apparent decrease in secretory activity and no epithelial cell death were observed in Fos-deficient animals after castration. Fragmentation of nuclear DNA was measured by in situ terminal transferase reaction. DNA fragmentation was observed in the prostate epithelium of control mice after castration whereas no similar fragmentation was found in Fos-deficient animals. After castration an AP-1 complex accumulated in the prostate of Fos deficient mice which mainly consists of FosB, Fra-2 and JunD whereas in control animals the AP-1 complex in addition contained c-Fos. Our data strongly suggest that c-Fos is required for programmed cell death of prostate epithelial cells.

Animals↗

PubMed1998

Global stability of an age-structure model for TB and its applications to optimal vaccination strategies.

This article focuses on the study of an age-structure model for the disease transmission dynamics of tuberculosis in populations that are subjected to a vaccination program. We first show that the infection-free steady state is globally stable if the basic reproductive number R0 is below one, and that an endemic steady state exists when the reproductive number in the presence of vaccine is above one. We then apply the theoretical results to vaccination policies to determine the optimal age or ages at which an individual should be vaccinated. It is shown that the optimal strategies can be either one- or two-age strategies.

Age Distribution↗

PubMed1998

Augmentation of recombinant fibronectin polypeptide CH50 on the antitumor function of macrophages.

We prepared an anti-metastatic polypeptide, recombinant fibronectin polypeptide CH50, and finished the preliminary identification of its functions. In this paper, we studied the effect of this polypeptide on the function of macrophages. CH50 can significantly augment the production of nitric oxide(NO) by macrophages in a dose-dependent manner. The continuous presence of CH50 had a much stronger effect. In the presence of CH50, the cytotoxicity of macrophages to melanoma B16/F1 cells was significantly enhanced, and a stronger effect was obtained if CH50 was present continuously. CH50 polypeptide and IFN-gamma have a synergistic effect on the production of NO by macrophages and the cytotoxicity of macrophages on tumor cells. In the in vivo experiments, CH50 can inhibit the growth of tumor cells, and have a better effect in the presence of IFN-gamma. Our results suggest that recombinant fibronectin polypeptide CH50 has two functions: one is to inhibit the metastasis of tumor cells, and the other one is to augment the function of macrophages. And this polypeptide will be potentially useful in tumor therapy.

Animals↗

PubMed1998

[Regulation of myocardium beta-adrenoceptors pathway in ventricular remodeling of heart failure patients].

To study the role of myocardium beta-adrenoceptors pathway in ventricular remodeling of heart failure patients. beta-adrenegic receptor density (Bmax) and the content of cAMP were measured in the papillae of left ventricle and blood lymphocyte of 20 patients suffered from heart failure (CHF) (NYHZ classification II to III) Bmax were investigated using 3H-dihydroalpheolol as ligand. cAMP were assessed by competitive immunoassay. Left ventricle mass index (LVMI) were measured using echocardiogram. The results showed that the Bmax and cAMP in failing myocardium significantly negatively correlated with LVMI (r = -0.77, P < 0.01 and r = -0.46 P < 0.05 respectively); the Bmax of myocardium and blood lymphocyte in CHF patients with NYHA III (63 +/- 12 fmol/mgpro and 514 +/- 115 fmol/10(7) cell) significantly lowered than that of NYHA II patients (94 +/- 20 fmol/mgpro and 702 +/- 138 fmol/10(7) cell); and the Bmax of myocardium and blood lymphocyte in patients with abnormal LVMI (62 +/- 12 fmol/mgpro and 516 +/- 122 fmol/10(7) cell) decreased more significantly than that with normal LVMI patients; even in nromal LVMI patients (92 +/- 21 fmol/mgpro and 682 +/- 146 fmol/10(7) cell), the Bmax of blood lymphocyte was already decreased (P < 0.01), when comparing with controls. The intralymphocyte cAMP content sygnificantly decreased than that of controls (P < 0.05). These results indicated that Bmax could reflect the severity of ventricle remodeling and the impairment of myocardium. The regulation of myocardium intracellular messenger transduction was earlier than the pathologic structural change of LV remodeling.

Adult↗

PubMed1998

Effect of low HDL combined with hypertriglyceridemia in coronary artery disease patients on PGI2 biological activity in relation to lipid regulating treatment.

The purpose of this study was to investigate the effect of low high-density-lipoprotein (HDL) combined with hypertriglyceridemia in coronary artery disease (CAD) patients on prostaglandin I2 (PGI2) biological activity in relation to lipid regulating treatment. The inhibitory rate of PGI2 on ADP-induced platelet aggregation was used as the index for PGI2 biological activity. Twenty health individuals served as normal controls. CAD group consisted of 20 patients with low HDL combined with hypertriglyceridemia. The results showed that, before the treatment, the stabilizing effect on PGI2 activity decreased significantly in CAD group when compared with the control group (P < 0.01). One month after the treatment, HDL level in CAD group increased significantly and TG level significantly decreased (P < 0.001). The different effect on PGI2 activity was no longer found between CAD group and control group (P > 0.05), further confirming the protecting effect of HDL on PGI2 biological activity. Low HDL is considered as an important risk factor of CAD, therefore, impaired PGI2 biological activity and increased platelet aggregation might be responsible mechanisms. Furthermore, raising HDL level by lipid regulating treatment could restore the protective effect of HDL on PGI2 and might be helpful in the prevention of the acute coronary syndrome.

Coronary Disease↗

PubMed1998

Effect of fragment Asp1961-Glu1978 in fibronectin on the expression of triple-domain polypeptide in E. coli.

Two plasmids were constructed and used to express two triple-domain recombinant polypeptide of human fibronectin (FN). The cDNAs in plasmids code for two polypeptides, CH62 (Pro1239-Ser1515 of FN linked with Ala1690-Val2049 through Met) and CH63 (CH62 without Ile1850-Glu1978). The expression level of CH62 in E. coli was very low, but that of CH63 was very high. The results suggests that Asp1961-Glu1978 in FN is a key sequence influencing the expression of triple-domain polypeptide in E. Coli. After being dissolved and renatured, CH63 can be purified by heparin-agarose affinity chromatography. Both of the cell-binding domains in the recombinant polypeptide were functional. The production of CH63 provides a fundamental basis for further study of recombinant products with better anti-metastasis function.

Animals↗

PubMed1998

The effect of neferine on foam cell formation by anti-low density lipoprotein oxidation.

Oxidatively modified low density lipoprtein (LDL) plays an important role in atheroslerosis (AS) development. To investigate the role of neferine (Nef) in anti-LDL oxidation and foam cell formation, the lipoprotein was derived and subjected to three different treatments: N-LDL (normal LDL), Cu2+ + LDL and Cu2+ + Nef + LDL. The LDLs were put at 25 degrees C for 24 h and the thiobarbituric acid reactive substance (TBARS) values were determined. They were 0.57 +/- 0.2, 6.01 +/- 0.22 and 2.26 +/- 0.13 nmol/mg protein, respectively. The difference was very significant (P < 0.01) for each two groups by t test. Mouse peritoneal macrophage (M phi) were exposed to 50 micrograms protein/ml of Cu2+ + LDL and Cu2+ + Nef + LDL at 37 degrees C for 60 h. The tryglyceride (TG) and total cholesterol (TC) content in M phi were assayed. The results showed that Cu2+ + LDL was more efficient than Cu2+ + Nef + LDL in stimulating lipid accumulation in M phi (P < 0.001). The study demonstrated that Nef could inhibit Cu(2+)-mediated LDL oxidation and thereby inhibiting macrophage-derived foam cell formation.

Alkaloids↗

PubMed1998

Apoptosis-associated gene expression in the corpus luteum of the rat.

The involution of the corpus luteum (CL) at parturition is an example of physiological apoptosis, a complex process involving massive vascular regression while luteal cells undergo apoptosis. In the present study, changes in gene expression associated with physiological apoptosis were examined. Three genes isolated in our laboratory because of their association with apoptotic processes in the ovary, mammary gland, and prostate served as the focus of our investigation: Y81, Gas-1, and the gene IAP encoding integrin-associated protein. Y81 is a novel gene for which three transcripts are apparent. A Y81 cDNA clone representing the longest transcript has been isolated; it shows an open reading frame exhibiting a region of very high homology with members of the frizzled family, the prototypes of which are cell autonomous polarity genes encoding seven-pass transmembrane receptor proteins, for example the receptor for Wingless. Gas-1 is known as a growth-arrest gene that inhibits DNA synthesis when microinjected into cells. Integrin-associated protein is a beta 3-integrin-binding protein for which, recently, a thrombo-spondin-binding activity has been recognized. These three genes, all sharply up-regulated in the course of physiological involution processes in the ovarian CL, in mammary gland, and in prostate, seem promising candidates-by virtue of their specific expression in distinct tissues undergoing programmed cell death-as mediators of stimuli leading to apoptosis and subsequent phagocytosis. In this study, sulfated glycoprotein-2, previously observed in many instances of physiological apoptosis, was further employed as an indicator for incipient apoptosis, and stromelysin was followed as a marker for the tissue remodeling activity that is intimately associated with apoptosis during involution.

Amino Acid Sequence↗

PubMed1998

Reduced cost of extremity free flap monitoring.

We analyzed the results and cost-effectiveness of our protocol for free flap monitoring in extremity patients. Of 70 consecutive free flaps to the upper and lower extremity that were monitored by laser Doppler flowmeter, 62 were managed on the hospital ward immediately after recovery from general anesthesia. The duration of laser Doppler monitoring was 5 days. Perfusion compromise occurred in three flaps, two of which occurred in the recovery room and were initially detected by the laser Doppler and successfully salvaged by early exploration. The average equipment cost for the use of the laser Doppler flowmeter for 5 days was significantly less than the cost of an intensive care unit bed for a single day. Our experience confirms that monitoring free flaps with laser Doppler is cost-effective and indicates that a specialized care bed after the recovery room is not necessary in routine extremity cases. Since no vascular complication occurred beyond the second postoperative day, this study suggests that the duration of laser Doppler monitoring can be discontinued on the third postoperative day.

Adolescent↗

PubMed1998

Numerical simulation of SAR and B1-field inhomogeneity of shielded RF coils loaded with the human head.

The finite-difference time-domain (FDTD) method is combined with the method of moments (MoM) to compute the electromagnetic fields of shielded radio-frequency (RF) coils loaded with an anatomically accurate model of a human head for high-frequency magnetic resonance imaging (MRI) applications. The combined method can predict both the specific energy absorption rate (SAR) and the magnetic field (known as the B1 field) excited by any RF coils. Results for SAR and B1 field distribution, excited by shielded and end-capped birdcage coils, are calculated at 64, 128, 171, and 256 MHz. The results show that the value of SAR increases when the frequency of the B1 field increases and the B1 field exhibits a strong inhomogeneity at high frequencies.

Algorithms↗

PubMed1998

Impact of work site health promotion on stages of dietary change: the Working Well Trial.

The stages of change construct has been applied to healthful dietary behavior in cross-sectional studies. This report examines associations of stages of change with diet prospectively and addresses whether (1) baseline stage of change predicts participation, (2) forward changes in stage movement were greater in treatment work sites, and (3) change in stage was associated with adoption of healthful diets, using data from a cohort of 11,237 employees. Findings indicate that persons in later stages of change reported higher participation levels. Employees from intervention work sites who were in preaction stages at baseline were much more likely to shift into action and maintenance stages than controls. Changes in dietary stage of change were associated with decreases in fat intake and increases in fiber, fruit and vegetable intake. Net change in diet due to the intervention was modest. Stage of change appears to be useful for understanding mediators of health promotion intervention effectiveness.

Adult↗

PubMed1998

Protective immunity in mice elicited by living infective third-stage hookworm larvae (Shanghai strain of Ancylostoma caninum).

OBJECTIVE: To elucidate the mechanisms of protective immunity in mice elicited by living hookworm (Ancylostoma caninum third-stage infective larvae (L3). METHODS: The number of migrating infective larvae recovered from the lungs was used as an endpoint for vaccine immunity. The timing of maximal L3 lung entry was determined by counting the number of lung larvae at several time points after infection with 500 or 1000 L3. Mice were immunized either orally or subcutaneously with 500 L3, followed by two boosts of L3 once every two weeks. The immunized mice were challenged orally with 500 L3 one week after the final boost. To evaluate the protective immunity, the number of L3 recovered from the lungs of the immunized mice during the time of maximal larval entry was compared with that of controls. Host immunity was also evaluated by comparing circulating anti-L3 antibodies between immunized and controlled mice, using both enzyme immunoassays and immunoblotting techniques, and by lung histopathology. RESULTS: The peak time of larval entry into the lungs occurred 48 hours after infection. Mice immunized either orally or subcutaneously with L3 exhibited a marked reduction (90.2% and 86.2% respectively) in the number of recovered lung larvae in comparison to controls (P < 0.01). The protection might be associated with circulating anti-L3 antibodies, including antibodies directed against 132-200 kDa L3 antigens, as well as three major antigens ranging from 28 to 51 kDa. Larvae migrating through the lungs of vaccinated mice showed cuticular damages accompanied with host-inflammatory cell invasion. CONCLUSIONS: Immunization with living L3 protects mice against lung invasion after challenged with hookworm infection. Vaccine immunity is associated with circulating antibodies against L3 antigens and lung inflammatory responses. The mouse model is potentially useful for developing a hookworm vaccine.

Ancylostoma↗

PubMed1998

Effect of artemether on glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and pyruvate kinase of Schistosoma japonicum harbored in mice.

AIM: To study the effect of artemether (Art) on glyceraldehyde-phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK), and pyruvate kinase (PK) of S japanicum. METHODS: Mice infected with schistosome cercariae for 32-38 d were treated ig with Art 100-300 mg.kg-1 and killed 24-72 h after medication for collection of schistosomes. The activities of GAPDH, PGK, and PK of the worms were determined by measuring the formation of NADH or consumption of NAD. The lactate content of the worms was also measured. RESULTS: After the infected mice were treated ig with Art 300 mg.kg-1 for 24 h, the inhibition rates of GAPDH were 13% (Male) and 21% (Female), and 48 h later the inhibition rates of the enzyme were 6% (Male) and 28% (Female). When Art 300 mg.kg-1 was given to infected mice for 24 h and 48 h, the inhibition rates of PGK were 60% (Male) and 48% (Female) as well as 75% (Male) and 62% (Female), respectively. Similar results were seen in PK activity. At 72 h after treatment the reduction rate of lactate content in Female worm was 72%, while that of Male was 48%. CONCLUSION: In the glycolytic pathway of both Male and Female schistosomes, PGK and PK activities were inhibited by Art. The GAPDH activity of Female worms was also susceptible to Art, While that of Male worms showed only temporary inhibition after treatment with Art. The Art reduced lactate content more in Female than in Male worms.

Animals↗

PubMed1998

Preventive effect of artemether in rabbits infected with Schistosoma japonicum cercariae.

AIM: To study the effect of artemether (Art) for prevention of schistosomal infection. METHODS: Rabbits with single infection or reinfection with Schistosoma japonicum cercariae were treated intramuscularly (i.m.) or intragastrically (i.g.) with Art 5 -20 mg.kg-1 on d 7-15 after the first infection, followed by various regimens. RESULTS: When rabbits were injected i.m. Art 7.5 mg.kg-1 (i.e., one half of the effective dose given i.g. on d 7) followed by once every week for twice, the female worm reduction rate was only 42%. In infected rabbits treated i.g. with Art 10-20 mg.kg-1 given in the same administration schedule, the female worm reduction rates were > 91%. When Art 15 mg.kg-1 was given to rabbits on d 7-14 and the following dose of the drug was given at intervals of 7-14 d, the female worm reduction rates were > 94%. In rabbits reinfected with cercariae, the female reduction rate of Art given i.g. once a week for 3 times since d 8 after the first infection was 96% which was similar to that given once a week twice since d 14 after the first infection. CONCLUSION: Art should be given i.g. on d 7-15 after infection, followed by repeated dosing once every 7-15 d for a total of 3 doses. Art given i.g. daily for 2 consecutive days or given at 1-wk intervals since 7-15 d after infection also showed preventive effect.

Animals↗

PubMed1998

[Improvement of mouse early embryo development in vitro by co-culture with human oviductal epithelial cells in serum-free medium].

OBJECTIVE: To examine the effect of human oviductal epithelial cells on early mouse embryonic cleavage and growth in vitro. METHODS: Ninety 2-cell mouse embryos were co-cultured with human oviductal epithelial cells in DMEM/Ham's F12 + 0.3% bovine serum albumin(BSA) + estradiol (E2) and ninety embryos cultured in DMEM/F12 + 0.3% BSA + E2 alone as control. RESULTS: Among the embryos co-cultured with oviductal epithelial cells, 82% developed to the morulae stage, 77% cavitated to blastocysts with 63% hatching, as compared with 45% to morulae stage, 13% to blastocysts and none hatching in the controls. Co-cultured embryos cleaved significantly faster than control and showed no or less fragmentation than those in the control. CONCLUSION: These results suggested that human oviductal epithelial cells can support early embryonic development and yield a reasonable number of embryos with good quality up to the blastocyst stage.

Animals↗

PubMed1998

[Application of VNTR D17S30 locus polymorphism in the paternity test].

A sensitive and rapid PCR-based technique was adopted to genotype the VNTR D17S30 locus. It was confirmed through the genetic analysis of 20 normal families that the inheritance of D17S30 locus coincides with Mendelian law as simple co-dominant. Retrospective analysis of 100 paternity cases demonstrated that D17S30 locus could be used in forensic paternity test in our country. The exclusion probability estimated from allele frequencies of D17S30 locus (74.04%) does not differ significantly from the observed rate of exclusion (80.00%) in these cases. In all excluded paternity cases there are two in which the exclusion evidence is solely provided by the D17S30 locus.

Chromosomes, Human, Pair 17↗

PubMed1998

[The development of SH-C1 autobiochemical analyzer].

As a miniature automatic analyzer, SH-C1 analyzer can be divided into five parts: the diluter, the circular reaction plate, the photometer, the electronic control board and the main microcomputer system with CRT monitor. The paper discusses its general structure and its key parts: the double-beam high precision photometer and the diluter controlled by microprocessors. The paper also describes the software system and the properties of the instrument.

Autoanalysis↗