Search PubMed⌕ Search

Biomedical subjects

F Chen

Publications and source records attributed to F Chen.

At least 217 records · Page 12Linked to original sources
PubMed2000

Predicting color kinetics during red Asian ginseng (Panax ginseng) preparation.

A red Asian ginseng preparation was prepared as follows: fresh Asian ginseng (Panax ginseng) roots were first steamed for half an hour to several hours, and then the steamed roots were dried into died roots (red Asian ginseng, 10% moisture content, on a dry basis). During steaming, the color of ginseng (white) turned yellow and brown during subsequent steaming. Color is an important index for grading red Asian ginseng. In this study, the effects of drying time and temperature on the surface color formation (L, a/b) of the Asian ginseng, and the color formation (L, a/b) of the red Asian ginseng powder were investigated. The value of L decreased, while the value of a/b increased as drying proceeded; the value of L was slightly influenced by the drying temperature, but the value of a/b was markedly influenced. With respect to the color of the final product (red ginseng), the value of L was slightly influenced by steaming time and temperature, while the value of a/b was increased as steaming time and drying temperature increased. Based on the nth-order rate equation and Arrhenius equation, a kinetic model for describing these effects was established, and the results were satisfactorily fitting.

Algorithms↗
PubMed2000

Role of p53 in cell cycle regulation and apoptosis following exposure to proteasome inhibitors.

In this study, we explored what effect inhibitors of the 26S proteasome have on cell cycle distribution and induction of apoptosis in human skin fibroblasts and colon cancer cells differing in their p53 status. We found that proteasome inhibition resulted in nuclear accumulation of p53. This was surprising because it is thought that the degradation of p53 is mediated by cytoplasmic 26S proteasomes. Nuclear accumulation of p53 was accompanied by the induction of both p21WAF1 mRNA and protein as well as a decrease in cells entering S phase. Interestingly, cells with compromised p53 function showed a marked increase in the proportion of cells in the G2-M phase of the cell cycle and an attenuated induction of apoptosis after proteasome inhibition. Taken together, our results suggest that proteasome inhibition results in nuclear accumulation of p53 and a p53-stimulated induction of both G1 arrest and apoptosis.

Acetylcysteine↗
PubMed2000

Anti-HBV effect of targeted antisense RNA against HBV C gene.

OBJECTIVE: To investigate the anti-HBV effect of targeted antisense RNA to hepatic cells. METHODS: pREP4-aC which would transcript antisense RNA against HBV C gene in eukaryotic cells were delivered into 2.2.15 cells by glactosylated poly-L-lisine (Gal-PLL), and the positive cells were selected. HBsAg, HBeAg and HBV DNA produced by 2. 2.15 cells were detected with ELISA or Southern blot during the experiment, and the cytotoxicity of targeted antisense on 2.2.15 cells was observed. RESULTS: The inhibition effect on HBsAg, HBeAg and HBV DNA occurred at the 24th hour after delivery and reached the highest level at the 6th day, and kept at lest two months. No cytotoxicity on 2.2.15 cells was observed. CONCLUSION: The targeted antisense against HBV C gene by delivery of Gal-PLL could effectively inhibit the antigen expression of HBV and DNA replication.

Antiviral Agents↗
PubMed2000

Cell phenotype-dependent splicing reflecting differential promoter usage for EBNA transcripts in EBV-carrying cells.

Three types of virus-host cell interactions have been described in cells latently infected with EBV: EBNA 1 expression in type I Burkitt's lymphoma cell lines (BL), EBNA 1, LMP1 and 2 expression in most nasopharyngeal carcinomas (NPC) and EBNA 1-6 with LMP 1 and 2 expression in group III BL-lines as well as lymphoblastoid cell lines (LCL). Two group I BL lines that express only EBNA 1 were found to initiate their EBNA 1 mRNA transcription from a promoter in the Bam HI Q-fragment. They use a sequence at +210 bp relative to the Fp transcription initiation site in group I BL cell lines. The Fp promoter-region seems to be activated in the lytic cycle. LCLs initiate their transcription from one of several upstream sites, usually the Cp promoter or, less frequently, one of several Wp-promoters. Using RNA-reverse transcription polymerase chain reaction (RT-PCR), we have now shown that EBV carrying cells that do not express EBNA 2-6 always splice their EBNA mRNA at the Q-exon, while EBNA 2-6 positive cells use either the Cp or one of the Wp promotors. When EBNA 2-6 are downregulated by somatic cell hybridisation between EBNA 1-6 positive B-cell lines and non B-cells of hematopoetic, epithelial or fibroblastic origin that express the phenotype of the non-B cell parent, the parental usage of Cp/Wp is switched off, and the Q-exon is activated. NPC cells show the same pattern of promoter usage as the hybrids with non-B phenotype. Group III BL cells use both promoter regions. Thus, the virus can use two alternative programs, depending on the cell phenotype. The "EBNA-1 only" program is activated from the Q-promoter. In cells with an immunoblastic (LCL or BL group III) phenotype, the upstream Cp/Wp promoters generate a 100 kb. long pre-mRNA, from which all the EBNAs are spliced. As a rule, only one of the two programs is used for each phenotype, except for the BL group III cells that began as group I but subsequently developed into a more LCL-like cell. Such cells used both promoter regions, with or without activation of the lytic cycle.

Animals↗
PubMed2000

5-HT transporter sites and 5-HT1A and 5-HT3 receptors in Fawn-Hooded rats: a quantitative autoradiography study.

BACKGROUND: The neuroanatomical profiles of 5-HT1A receptors, 5-HT3 receptors, and 5-HT transporters (5-HTT) in the brain of the Fawn-Hooded (FH) rat, particularly mesocorticolimbic regions, are not fully elucidated. METHODS: By means of in vitro quantitative autoradiography, we used [3H]citalopram, [3H]8-OH-DPAT, and [3H]GR65630 to label 5-HTT, 5-HT1A receptors, and 5-HT3 receptors in the brain of alcohol-naïve FH rats, Wistar-Kyoto (WKY) rats, and FH rats given free access to 5% ethanol and/or after 24 to 48 hr withdrawal. RESULTS AND CONCLUSIONS: In alcohol-naïve rats, FH rats displayed significantly higher (p < 0.05) densities of [3H]citalopram binding in the nucleus accumbens (+30%), lateral septum (+37%), ventral pallidum (+21%), and ventral tegmental area (+24%), as well as an increased binding of [3H]8-OH-DPAT to 5-HT1A receptors in the frontal and parietal cortex (+33%), occipital and temporal cortex (+25%), and hippocampal CA3 region (+31%), compared with WKY rats, whereas both strains exhibited comparable [3H]GR65630 binding to 5-HT3 receptors. Compared with control FH (naive) rats, chronic ethanol consumption significantly decreased (p < 0.(15)[3H]8-OH-DPAT binding in the frontal and parietal cortex (-15%) but significantly increased binding (p < 0.05) in the entorhinal cortex (+25%), retrosplenial granular cortex (+20%), and hippocampal CA1 (+14%) and CA3 regions (+18%). Moreover, ethanol withdrawal induced the same extent of increased [3H]8-OH-DPAT binding in the entorhinal and retrosplenial cortex as seen in FH (chronic) rats. In contrast, [3H]8-OH-DPAT binding in the hippocampal CA1 and CA3 regions was decreased by -9% and -20% from the level of chronic ethanol-treated FH rat (p < 0.05) and returned to the control level seen in FH (naïve) rats. SIGNIFICANCE: The elevated 5-HT transporters and 5-HT1A receptors in the mesocorticolimbic areas in FH rats may reflect a potential innate altered transmission at serotonergic synapses, which possibly may affect the high intake of alcohol in FH rats. The region-specific alterations of 5-HT1A receptors in FH rat brain after ethanol challenges suggest that 5-HT1A receptors are sensitive to ethanol challenges, whereas 5-HTT are apparently insensitive.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2000

Participation of MAP kinase p38 and IkappaB kinase in chromium (VI)-induced NF-kappaB and AP-1 activation.

Epidemiological studies demonstrate that environmental and occupational exposure of chromium(VI) [Cr(VI)] or Cr(VI)-containing particles can cause a number of human diseases, including inflammation and cancer. The biological mechanisms responsible for the initiation and progression of diseases resulting from exposure to Cr(VI) are not fully understood. The present studies evaluated the ability of Cr(IV) to induce activation of NF-kappaB and AP-1, two important transcription factors governing the expression of many early response genes involved in inflammation and carcinogenesis. The activation of NF-kappaB and AP-1 by Cr(IV) was dose dependent. Aspirin, a well-established antioxidant, substantially inhibited Cr(VI)-induced activation of both NF-kappaB and AP-1. SB202190, a specific inhibitor for p38, attenuated AP-1 activation induced by Cr(IV), whereas PD98059, a specific inhibitor for Erk, exhibited no effect on Cr(IV)-induced AP-1 activation. Blockage of NF-kappaB signaling pathway by a transient transfection of a dominant negative expressing vector for IkappaB kinase beta resulted in inhibition of Cr(IV)-induced NF-kappaB, but not AP-1 activation. These data suggest that the activation of AP-1 or NF-kappaB by Cr(IV) is through the involvement of MAP kinase or IKK pathway, respectively.

Animals↗
PubMed2000

[A special software for area and volume measurement and 3D image of skin expander].

OBJECTIVE: A special software for measuring expanded skin area and volume and creating a 3D image of skin expander protrusion has been introduced. METHODS: The 3D coordinates of all the points on the surface were obtained by means of interpolation in computer, according to its base, central horizontal and vertical sections that should be adopted in advance. This software was programmed with C language and performed in Microsoft Windows. RESULTS: The area, volume, and 3D image were acquired according to 3D coordinates. The deviation of the software measurement was less than 4% of actual sizes at most in our reliability demonstration. CONCLUSION: This software, combined with our protocol of conversion from tridimensional surface to a plane reported previously, makes up a preferable scheme in this field.

Adult↗
PubMed2000

Effect of all-trans retinoic acid on growth of xenograft tumor and its metastasis in nude mice.

OBJECTIVE: To study the effect of all-trans retinoic acid on growth of xenograft tumor and its metastasis in nude mice. METHODS: Human gastric cancer BGC-823 and MKN-45 cells were inoculated into spleen subcapsule of nude mice, respectively. The nude mice were subsequently administered with all-trans retinoic acid every other day. Food consuming and body weight of nude mice were measured weekly. Six weeks later, the nude mice were killed. Xenograft tumors in spleen and metastatic tumors in liver were pathologically examined. Microvessel density in the tumors was detected immunohistochemically, and serum carcinoembryonic antigen was measured by radioimmunoassay. RESULTS: After the nude mice were fed with all-trans retinoic acid, the growth of splenic tumor and its liver metastasis were inhibited and the metastatic rates decreased by 50% (BGC-823) and 33.3% (MKN-45), respectively. The microvessel density in splenic and hepatic tumors reduced by 28.58% and 35.47% (BGC-823), 19.45% and 14.52% (MKN-45), respectively. The concentration of carcinoembryonic antigen decreased by 50.24% (BGC-823) and 48.10% (MKN-45). CONCLUSION: All-trans retinoic acid may effectively inhibit the growth of xenograft tumor in spleen and its metastasis to liver in nude mice, which can be corroborated by the decrease of carcinoembryonic antigen and microvessel density.

Animals↗
PubMed2000

Polymorphism of human platelet alloantigen in Chinese patients with acute myocardial infarction and acute ischemic stroke.

OBJECTIVE: To investigate the gene frequencies of 5 major human platelet alloantiqens (HPA 1-5) in Chinese population and to assess if polymorphism of HPA was associated with Chinese acute myocardial infarction (AMI) and acute ischemic stroke (AIS). METHODS: HPA 1-5 genotyping was performed by PCR using allele specific primers and restriction enzyme digestion based on PCR products in 95 AMI cases, 188 AIS cases and 270 normal controls. Gene frequency distribution was tested by Hardy-Weinberg equilibrium and comparison of HPA gene frequencies between the patient and control groups by chi 2 test. RESULTS: The gene frequencies of HPA 1-5 were the followings: HPA1a: 91%; 1b: 9%; HPA 2a: 94%; 2b: 6%; HPA 3a: 83%; 3b: 17%; HPA 4a: 98%; 4b: 2%; HPA5a: 97%; 5b: 3%. We found there were no significant differences in HPA 1-5 gene frequencies between AMI patients and normal controls. In AIS patients group HPA-2a allele frequency was significant higher than in controls, but this allele gene frequency in two groups (0.94 and 0.99) was very close and too many subjects in these two groups were overlapped. Otherwise no differences was found in other 4 HPA systems between cases and controls. CONCLUSION: Polymorphism of HPA were not inherited risky factors and not associated with chinese arterial thrombotic diseases such as AMI and AIS.

Adult↗
PubMed2000

Relationship between gene expression of nitric oxide synthase and androgens in rat corpus cavernosum.

OBJECTIVE: To clarify the dependence of neural nitric oxide synthase mRNA (nNOSmRNA) and endothelial nitric oxide synthase mRNA (eNOSmRNA) on androgens (testosterone [T] and dihydrotestosterone [DHT]). METHODS: 160 male Sprague Dawley (SD) rats were divided into Groups A (56 rats, 5 weeks old), B (50 rats, 10 weeks old) and C (54 rats, 58 weeks old). Groups A, B and C were all subdivided respectively into five Subgroups. Subgroup 1: intact controls; Subgroup 2: castrated; Subgroup 3: castrated with testosterone undecanoate 25 mg/kg.mon-1, intramuscular injection, Subgroup 4: castrated with testosterone undecanoate 50 mg/kg.mon-1, intramuscular injection and Subgroup 5: treated with finasteride 4.5 mg/kg.day-1, orally. Four and ten weeks after treatments described above, one half of the rats were killed. Serum samples were taken for measurements of T, free testosterone (FT) and DHT by radioimmunoassay. Penile samples were treated with liquid nitrogen and then stored at -80 degrees C. nNOSmRNA and eNOSmRNA were detected by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) and Dot blot. RESULTS: There was no significant difference between Subgroup 1 and Subgroup 2 or Subgroup 5 in all Groups A, B and C. The expression of penile eNOSmRNA of Group A was significantly increased (4 weeks model) (P < 0.05) or increased (10 weeks model) (P > 0.05) in Subgroup 2 or 5 compared with those in Subgroup 1. There was no significant difference between Subgroup 1 and Subgroup 2 or Subgroup 5 of Group B in 4 weeks model (P > 0.05). There was an elevation when animals were castrated or treated with finasteride in the 10 weeks model. The expression of penile eNOSmRNA of Group C was significantly increased (10 weeks model) (P < 0.05) or increased (4 weeks model) in Subgroup 2 compared with those in Subgroup 1. The production of eNOSmRNA in Subgroup 5 was also increased (including 4- and 10-week models). When T was supplied for castration, the penile eNOSmRNA was decreased to some extent; the greater the dose of T given, the lower penile eNOSmRNA was observed. CONCLUSIONS: The expression of eNOSmRNA in SD rat penile tissue increases while T or DHT diminishes. Sometimes androgens modulate penile eNOSmRNA in opposite directions. There is no correlation between the expression of nNOSmRNA and androgens (including T and DHT). Androgens give rise to penile erection probably not via the NOS pathway.

Androgens↗
PubMed2000

[Clinical studies on the use of hyperbaric oxygen in replantation of young permanent teeth].

OBJECTIVE: To investigate the treatment effects of hyperbaric oxygen(HBO) in replantation of young permanent teeth. METHODS: A total of 138 luxation injuries to young permanent teeth undergoing treatment. The teeth were replanted and then divided into 2 groups. The HBO group was exposed to 0.25 MPa pure oxygen 40 x 2 minutes each day for 10 days continuously while the control group were compared. RESULTS: The total effective rates of the HBO group and the control group were 97.26% and 70.77% respectively, and showed significant difference (P < 0.05); respective frequencies of missing tooth after 1 year were 1.37% and 18.46%, and provided a statistical significance (P < 0.001). CONCLUSION: HBO used in replantation of luxated young permanent teeth could promote the recovery of periodontal membrane, pulp, and prevent resorption of root.

Adolescent↗
PubMed2000

[Polymorphism of human platelets alloantigens in Chinese patients with acute myocardial infarction and acute ischemic stroke].

OBJECTIVE: To investigate the gene frequencies of 5 major human platelets alloantigens (HPA 1 - 5) in Chinese population and to assess if polymorphism of HPA is associated with acute myocardial infarction (AMI) and acute ischemic stroke (AIS) in the Chinese. METHODS: HPA 1 - 5 genotyping was performed with PCR using allele specific primers and restriction enzyme digestion based on PCR products in 95 AMI patients, 188 AIS patients and 270 normal controls. Gene frequency distribution was tested by Hardy-Weinberg equilibrium. Comparisons of HPA gene frequencies between the patient and control groups were made by chi(2) test. RESULTS: The gene frequencies of HPA 1 - 5 were listed as follows: HPA1a, 91%; HPA 1b, 9%; HPA 2a, 94%; HPA 2b, 6%; HPA 3a, 83%; HPA 3b, 17%; HPA 4a, 98%; HPA 4b, 2%; HPA 5a, 97%; HPA 5b, 3%. No significant differences were found in HPA 1 - 5 gene frequencies between AMI patients and normal controls. In AIS patient group, HPA-2a allele frequency was significantly higher than that in controls, but this allele gene frequency in the two groups was very close (0.99 and 0.94, respectively) and too many subjects in the two groups were overlapped. No differences were found in the other 4 HPA systems between patients and controls. CONCLUSION: Polymorphism of HPA is not an inherited risk factor and is not associated with Chinese arterial thrombotic diseases, such as AMI and AIS.

Acute Disease↗
PubMed2000

[Diagnosis and treatment of early colorectal cancer].

OBJECTIVES: To study the diagnostic methods of early colorectal neoplasm before operation and to evaluate the value of these methods for selection. METHODS: Fifteen patients with early colorectal neoplasms were examined pre-operatively by general colonoscopy to observe macroscopic appearance, by magnifying endoscopy to classify pit pattern type, and by endoscopic ultrasonography (EUS) to assess the penetrating depth of cancer invasion as well as regional lymph node metastases. According to these findings, diagnosis and clinical staging were made and proper treatment protocols were established. RESULTS: The diameter of the tumors ranged from 1 to 6 cm. Most lesions were subpedunculate type (8/15, 53%). Eight cases belonged to pit pattern type III L + V (8/15, 53%). EUS showed mucosal cancer in 11 cases and submucosal cancer in 4. No lymph node metastasis was observed in any cases. Treatment methods included endoscopic polypectomy or endoscopic mucosa resection (EMR) in 6 cases, endo-surgery combined with open surgery in 2, and open surgery in 7. Pathological diagnosis showed mucosal carcinoma in 12 cases, submucosal carcinoma in 3. The accuracy of EUS was 93%. CONCLUSIONS: Magnifying endoscopy and EUS are useful for diagnosis of early colorectal cancer before operation, and correct preoperative staging of colorectal neoplasms is of significance in guiding treatment.

Colonoscopy↗
PubMed2000

[Resection of pelvic retroperitoneal neoplasm and reconstruction of iliac blood vessels: report of 22 cases].

OBJECTIVE: To study the surgical manipulation of iliac blood vessels invaded by pelvic tumors in order to raise the resection rate. METHODS: We reviewed 22 cases of resection for pelvic retroperitoneal tumors along with the reconstruction of iliac blood vessels in our hospital from July 1994 to January 2000. In 22 cases, 8 received operation on the right iliac arteries and veins, and 14 on the left. RESULTS: Follow-up for 4 months to 5 years and 10 months (average 3.6 years) showed that 3 patients had recurrence and needed secondary operation. All the grafts were patent except one vein graft occlusion 7 months after operation. CONCLUSION: Resection of pelvic retroperitoneal neoplasm combined with reconstruction of iliac blood vessels is safe, effective and practical to raise the excision rate and decrease the recurrence rate.

Adult↗
PubMed2000

[The ultrastructure of human and mouse cataractous lens epithelial cell apoptosis].

OBJECTIVE: To observe the relation between human senile cataract, mouse congenital cataract and lens epithelial cell apoptosis. METHODS: Transmission electron microscope was used to observe the apoptotic morphology of the lens epithelial cells in 4 cases with senile cataract and in 2 mice with congenital cataract. The comparisons were made between the cataractous and normal transparent lens epithelial cells in human being and mice. RESULTS: The apoptotic cells were found in senile cataract and mouse congenital cataract lens epithelial cells, while in all control lens epithelial cells they were few. CONCLUSION: Lens epithelial cells apoptosis is related to senile cataract and mouse congenital cataract formation.

Animals↗
PubMed2000

[An experimental research of taurine on H2O2-induced bovine lens epithelial cell apoptosis].

OBJECTIVE: To study the inhibitory role of taurine on H(2)O(2)-induced bovine lens epithelial cell apoptosis. METHODS: By terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) detection and bovine lens organ culture, we examined the affect of taurine on the number of H(2)O(2)-induced bovine lens epithelial cells with apoptosis, the related comparisons and statistic analyses were carried out. RESULTS: (1) Lens epithelial cell apoptosis began before lens opaqueness (lens became opaque after 6 hours of incubation, while the lens epithelial cell apoptosis was detected after 3 hours of incubation); (2) Taurine could apparently inhibit H(2)O(2)-induced bovine lens epithelial cell apoptosis. CONCLUSION: Taurine has an inhibitory role on H(2)O(2)-induced bovine lens epithelial cell apoptosis and can delay and ameliorate the occurrence and development of cataract.

Animals↗
PubMed2000

[Detection of hypermethylation of p15 gene in patients with acute leukemia by polymerase chain reaction].

OBJECTIVE: To explore the role of hypermethylation of p15 gene in the pathogenesis of acute leukemias. METHODS: DNA from 36 cases of acute leukemia were investigated using restriction enzyme digestion combined with polymerase chain reaction (PCR) technique. RESULTS: Hypermethylations of p15 gene were found in 22 (61.1%) patients, including 17 cases of acute non-lymphoblastic leukemia (ANLL) and 5 of acute lymphoblastic leukemia (ALL). ANLL patients exhibited p15 gene hypermethylations had higher WBC in peripheral blood (P < 0.05) and higher percentages of leukemia cells in bone marrow (P < 0.01). CONCLUSION: Inactivation of p15 gene due to hypermethylation may be involved in the pathogenesis of some acute leukemias.

Adult↗