Biomedical subjects

F Chen

Publications and source records attributed to F Chen.

At least 145 records · Page 8Linked to original sources

PubMed2001

[Effects of selective RAR or/and RXR retinoids on the proliferation and differentiation of NB4 cells and their mechanisms].

OBJECTIVE: To investigate the effects of RARbeta selective agonist and RARalpha antagonist (RARbeta +/RARalpha -) BMS453 in combination with RXR selective agonist (RXR+) BMS649 on the proliferation and differentiation of NB4 cells, and illustrate the mechanism. METHODS: The proliferation and differentiation of NB4 cells were detected by cell count, morphological observation, NBT reduction assay, immunofluorescence analysis, flow cytometry and RT-PCR. RESULTS: BMS453 in combination with BMS649 could significantly inhibited the growth of NB4 cell in the manner of dose and time dependence. NB4 cells treated with BMS453 and BMS649 were irreversibly committed to morphologically and functionally more differentiated granulocytic cells. When NB4 cells were treated with BMS453 and BMS649 for 0, 1, 3, 12, 24 and 48 h, RARalpha, RARbeta and RXRalpha expressions were up regulated at 1 h and 3h, respectively. As compared to ATRA, the situations had no significant difference. In contrast, BMS453 or BMS649 alone was ineffective on NB4 cells. CONCLUSION: BMS453 (RARbeta+/RARalpha-) in combination with BMS649 (RXR+) significantly and synergistically inhibit proliferation of NB4 cells and induce them into granulocytic differentiation, the mechanism of which may be mediated by the AF-2 activity of RXR.

Cell Differentiation↗

PubMed2001

[Early mortality and complications of abdominal aortic aneurysm repair: analysis of 186 cases].

OBJECTIVE: To study the early mortality and major complications of infrarenal abdominal aortic aneurysm (AAA) repair. METHODS: One hundred and eighty-six cases of infrarenal AAA, which underwent surgery in our hospital between January 1988 and December 2000, were selected. Early mortality and major complications were rated, and preoperative cardiac, pulmonary and renal condition, age and surgical impact were taken into account while evaluating the risk factors of early mortality and major complications. RESULTS: The early mortality was 5.0% for elective surgery and 57.1% for ruptured surgery. The early major complication rate for AAA repair was 18.4% in total, and 10.6%, 11.2%, 2.8%, 1.1% for cardiac complication, pulmonary complication, acute renal failure, stroke and hepatic insufficiency respectively. Coronary heart disease significantly predisposed the patients to the development of cardiac complications (chi 2 = 19.737, P < 0.01) while hypertension had no such effect (chi 2 = 1.870, P > 0.05). Abnormal pulmonary function, smoking and PaO2 less than 80 mmHg were responsible for postoperative pneumonia(chi 2 = 4.051, 5.885 and 5.162, P < 0.05), but not for adult respiratory distress syndrome(chi 2 = 0.127, 0.916 and 1.067, P > 0.05). Preoperative renal function was not related postoperative acute renal failure(chi 2 = 0.404, P > 0.05). Age more than 70 years or operation spanned more than 5 hours increased major complications(chi 2 = 16.119 and 10.163, P < 0.01) and early mortality(chi 2 = 16.119 and 10.163, P < 0.01). CONCLUSIONS: Multiple system organ failure is the leading cause of early mortality of AAA repair. Cardiac and pulmonary complications are commonly seen after AAA repair. Preoperative cardiac, pulmonary condition, age and surgical aspects greatly influence the early mortality and major complications.

Acute Kidney Injury↗

PubMed2001

[Surgical treatment of abdominal aortic aneurysms: report of 482 cases].

OBJECTIVE: To improve the safety of abdominal aortic aneurysm (AAA) repair. METHOD: The experience of 482 cases of AAA in surgical treatment and endovascular graft exclusion were reviewed from January 1960 to March 2001. RESULTS: Retroperitoneal approach and minimal incision was used for AAA operation. New methods for control of the "neck" of aneurysm, aneurysmectomy and endovascular graft exclusion were applied. The danger of AAA repair obviously decreased. The operative mortality was 5.2% and the five-year survival rate was 74.4%. CONCLUSION: The improvement of surgical and anesthetic techniques made AAA resection rapid and safe.

Adolescent↗

PubMed2001

[Comparison of production and characters of antisera from rabbits and laying hens].

Rabbits and laying hens were immunized with the conjugate of aflatoxin B1 oxime and bovine serum albumin (AFB1 O-BSA). The production processes, titers and specificities of antisera from rabbits and laying hens were investigated. In rabbits, the antisera started to be obviously produced after 60 days when the conjugate was firstly injected, reached peaks after 120 days, and began to go down after 135 days; while in laying hens, the antisera started to be largely produced after 90 days of the first injection, arrived to peaks after 135 days, and began to go down after 165 days. The maximum enzyme linked immunosorbent assay(ELISA) titer of rabbits' antisera was up to 1:30,000, whereas the maximum ELISA titer was only 1:8000 in laying hens. There are no apparent difference in the sensitivities and specificities of rabbits' and laying hens' antisera. Both antisera from rabbits and from laying hens can be used as ELISA reagents detecting AFB1 in agricultural commodities.

Aflatoxin B1↗

PubMed2001

Rapid analysis of momordicoside A in bitter melon by high performance liquid chromatography following solid phase extraction.

A rapid, simple and accurate method for the determination of momordicoside A has been established using solid phase extraction (SPE) followed by high performance liquid chromatography (HPLC). Sample was processed by SPE on a Carb cartridge (3 mL/250 mg), and was then determined by HPLC on a C18 column (4.6 mm i.d. x 250 mm, 5 microns) with V(acetonitrile):V(methanol):V(50 mmol/L potassium dihydrogen phosphate buffer) = 25:20:60 as mobile phase (0.8 mL/min) and UV detection at 208 nm. The calibration curves were linear from 10 mg/L to 1,000 mg/L (r2 = 0.9992). The analytical method was shown to be highly reproducible, giving all of the relative standard deviations and relative mean errors less than 10% for both intra-day and inter-day determinations. The absolute recoveries were greater than 90%.

Antineoplastic Agents, Phytogenic↗

PubMed2001

[Distributions of body mass index of Chinese adults].

Based on the Third China National Nutrition Survey conducted in 1992, the distribution of body mass index (BMI) in 44,485 adults aged 20-60 y was analyzed, and the cutoff points of BMI for overweight and obesity were also explored. The results showed that the BMI of Chinese adults was in logarithmic normal distribution. The average BMI of this population was 22.1 +/- 3.1. The 50th, 85th and 95th percentiles of BMI were 21.6, 24.9 and 27.4 kg/m2 respectively. The 85th percentile of BMI was much closer to the BMI cutoff points for overweight recommended by WHO, but the 95th percentile was much lower than WHO's cutoff points for obesity. The distribution of BMI based on age, gender and urban/rural areas was different and with statistical significance. It is considered that age and gender should be taken into account while setting up BMI cutoff points for the overweight and obesity of a population, as well as considering the relationships among BMI and morbidity and mortality, body fat composition, and some blood biochemical indexes.

Adult↗

PubMed2001

[Studies on synthesis and degradation of collagen at transcription level in liver fibrosis of rabbits with schistosomiasis japonica].

OBJECTIVE: To study the synthesis and degradation of collagen at the transcription level during liver fibrosis in rabbits with schistosomiasis japonica. METHODS: New Zealand rabbits infected with Schistosoma japonicum cercariae were served as animal models of liver fibrosis. The liver specimens were collected through operations at 4, 6, 8, 10, 12, 16, 20, 24 and 28 weeks after infection. Type I collagen, type III collagen, type IV collagen, MMP-1 and MMP-9 mRNA levels of liver tissue were detected by RT-PCR plus dot blotting, and the size of egg granulomas and the degree of liver fibrosis were measured by histopathological examinations. RESULTS: Type I collagen, type III collagen, type IV collagen, MMP-1 and MMP-9 mRNA levels increased simultaneously in the early stage after the infection, mostly reaching their peaks at 10 weeks after infection. Compared with normal controls, type I collagen, type III collagen, type IV collagen, MMP-1 and MMP-9 mRNA levels increased by 12.0-, 11.0-, 6.6-, 10.0- and 11.0-fold, respectively, coinciding with the changes of egg granulomas. Thereafter, both collagen and collagenase mRNA levels decreased. Types I, III and IV collagen mRNA levels declined to 2-fold to 3-fold compared with normal controls (P < 0.05), while MMP-1 and MMP-9 mRNA levels declined to normal level (P > 0.05) at 28 weeks. This study showed that the synthesis and degradation of collagen remained dynamic balance in the early stage of schistosomiasis, while in the later stage the metabolism of collagen synthesis was higher than that of collagen degradation. CONCLUSION: It was confirmed at the transcription level that when the metabolism of collagen synthesis was higher than that of collagen degradation in rabbits with schistosomiasis japonica, liver fibrosis might be produced.

Animals↗

PubMed2001

[Analysis of essential oil from Artemisia annul L. by extraction of different methods].

Essential oils from Artemisia annul L. were extracted with CO2 supercritical fluid and steam distilation. The essential oils were analyzed and contrasted by GC-MS. 114 components were identified by computer index. The rate of total components by supercritical CO2 fluid extraction and steam distillation were 81.24% and 85.75% respectively. Some of them such as diphenylene-Methane, Phenyl-1-naphthylamine were discovered from the plant for the first time.

1-Naphthylamine↗

PubMed2001

[Subtotal laryngectomy reconstructed by platysma myocutaneous flaps].

OBJECTIVE: To study the feasibility, surgical techniques and the results of laryngeal function preservation during subtotal laryngectomy in laryngeal carcinoma. METHODS: A retrospective review was made of 13 patients treated by subtotal laryngectomy and laryngeal reconstruction from 1991 to 1996. Eleven patients were male and 2 were female. The age ranged from 46 to 72 years, with a mean of 53.25. All cases were of stage IV. The essence of this operation is to reconstruct the new larynx with two platysma myocutaneous flaps following subtotal laryngectomy. RESULTS: The success rate of voice rehabilitation was 100%. Among them, the acceptability rating scores in 11 cases were 7 and the intelligibility scores ranged from 95% to 98%. The other two cases had acceptability 5 and intelligibility form 90% to 94%. The three-year survival rate was 84.6% (11/13), 5-year survival rate was 76.9% (10/13). CONCLUSION: This form of laryngeal reconstruction in subtotal laryngectomy is helpful to restore laryngeal function and decrease the rate of total laryngectomy. The procedure is easy, safe and applicable to patients treated by subtotal laryngectomy.

Aged↗

PubMed2001

[Significance and expression of transforming growth factor beta in human nasal polyp tissue].

OBJECTIVE: To explore the pathogenesis of nasal polyposis and the expression of transforming growth factor beta (TGF-beta) in human inflammatory nasal polyps. METHODS: TGF-beta 1-3 in nasal polyp tissues and inferior turbinate mucosa of twenty-five polyposis patients were detected with immunohistochemistry alkaline phosphatase and anti-alkaline phosphatase (APAAP) method. The inferior turbinate mucosa of eight healthy volunteers were selected as control. Six polyp tissues were estimated with double immunolabeling and Western-blot analysis to compare the characterization of the TGF-beta isoforms expression and the proportion of macrophages and eosinophils in nasal polyp tissues. RESULTS: The expression of TGF-beta 1-3 in nasal polyps was significantly higher than that in nasal mucosa and indetecable in nasal mucosa from healthy volunteers; TGF-beta 1 was the main isoform detected in nasal polyps; TGF-beta positively was accompanied by numerous macrophage and eosinophil infiltration. CONCLUSIONS: TGF-beta mainly TGF-beta 1 is strongly expressed in nasal polyps and its mucosa, where it could be produced by macrophages and eosinophils. TGF-beta could induce modification of epithelium and connective tissue and therefore be involved in the pathogenesis of nasal polyposis.

Eosinophils↗

PubMed2001

[Surgery of substernal goiter].

OBJECTIVE: To study the surgical approaches and operative techniques for substernal goiter. METHOD: A retrospective study of 27 cases with substernal thyroid nodules was made in our hospital. RESULT: The operations on 27 patients with substernal nodules have been successfully carried out. Among them, 10 were goiters, 9 adenomas, 4 malignancy and 4 were thyroid cancer metastasizing to paratracheal or substernal nodes. Resection via cervical collar incision was adequate in 23 cases. Three thyroid cancers with paratracheal node metastasis were completely resected by sternotomy and only one thyroid cancer with paratracheal and substernal nodes metastasis was resected by combined thoracotomy and cervical collar incision. CONCLUSION: Resection via cervical collar incision for all retrosternal thyroid nodules were advised. The preliminary experience with this procedure suggests that it has some advantages in the management of substernal goiter, including: 1. ease of operation compared to both sternotomy and thoracotomy; 2. relatively low morbidity; 3. safe and reliable.

Adult↗

PubMed2001

[Value of surgical margin in directing the treatment of early laryngeal carcinoma after partial laryngectomy].

OBJECTIVE: To investigate the value of surgical margin in directing the treatment of early laryngeal carcinoma after partial laryngectomy. METHODS: We studied 87 cases of T1N0M0 and T2N0M0 laryngeal carcinoma in which the surgical margins were reserved during partial laryngectomy. The recurrence and survival rates between the positive and negative margin groups were compared; the survival between the positive margin groups with postoperative radiotherapy and negative groups; the survival between groups with and without postoperative radiotherapy in negative margins. RESULTS: Recurrent rate of the negative group was lower than that of the positive group (5.8% vs 33.3%, chi 2 = 10.64 P = 0.001). The estimated survival was higher in the negative group than in the positive group(P = 0.011), and also in tumor-free time(P = 0.007). The survival of those with positive surgical margin and received postoperative RT was lower than that with negative margins(P = 0.01). In the negative group, the difference in the survival between those with or without postoperative RT was not significant (P = 0.405). CONCLUSION: The prognosis of the positive margin group of the early laryngeal carcinoma was worse than that of the negative group, but postoperative RT can improve it; it is not necessary for the negative group to be treated by postoperative RT.

Adult↗

PubMed2001

[Severe complications of hysteroscopic surgeries: an analysis of 35 cases].

OBJECTIVE: To investigate the methods of earlier diagnosis, treatment and precautions on the severe complications of hysteroscopic procedures. METHODS: There were 12 921 cases of diagnostic hysteroscopy and 2 221 cases of operative hysteroscopy were performed. For diagnostic hysteroscopy B ultrasonography were scaned meanwhile and fluid media were used to distend the uterus. For operation hysteroscopy B ultrasonography or laparoscopy was used for monitoring. RESULTS: Thirty five cases of severe complications encountered. There were 9 cases of severe intraoperative bleeding. Foley catheter inserting, bleeding spots coagulating, uterine cavity tampon or hysterectomy were used to stop intraoperative and postoperative bleeding successfully. Eleven cases of uterine perforation were treated by conservativetherapy, laparoscopy or hysterectomy. An air embolism happened on hysteroscopic examination was survived with aggressive rescue. There were 4 cases of postoperative infection that had history of pelvic inflammatory disease and cured by antibiotics. Diuretic agent and saline infusion were used to treat 5 cases of transurethral resection of prostate (TURP) syndrome effectively. For 4 cases of post-ablationsterilization syndrome (PASS) dilating the cervix canal and expelling the hematometra, transcervical resection of adhesions or hysterectomy were managed effectively. One case of endometrial adenocarcinoma stage I a was diagnosed 8 years after transcervical resection of endometrium (TCRE) & transcervical resection of polyp (TCRP), and radical hysterectomy plus selective pelvic lymphadenectomy was performed. CONCLUSIONS: Foley catheter insertion is a simple and efficient method to stop uterine bleeding. Uterine adhesion is a high risk factor of uterine perforation. Monitoring by B ultrasonography or laparoscopy could not prevent uterine perforation. Prevention was essential for air embolism. Control the pressure of irrigating flow and operating time can reduce the incidence of TURP syndrome. To intensify follow-up is the best method to detect PASS and uterine adenocarcinoma.

Blood Loss, Surgical↗

PubMed2000

Evolutionary coadaptation of the motif 2--acceptor stem interaction in the class II prolyl-tRNA synthetase system.

Known crystal structures of class II aminoacyl-tRNA synthetases complexed to their cognate tRNAs reveal that critical acceptor stem contacts are made by the variable loop connecting the beta-strands of motif 2 located within the catalytic core of class II synthetases. To identify potential acceptor stem contacts made by Escherichia coli prolyl-tRNA synthetase (ProRS), an enzyme of unknown structure, we performed cysteine-scanning mutagenesis in the motif 2 loop. We identified an arginine residue (R144) that was essential for tRNA aminoacylation but played no role in amino acid activation. Cross-linking experiments confirmed that the end of the tRNA(Pro) acceptor stem is proximal to this motif 2 loop residue. Previous work had shown that the tRNA(Pro) acceptor stem elements A73 and G72 (both strictly conserved among bacteria) are important recognition elements for E. coli ProRS. We carried out atomic group "mutagenesis" studies at these two positions of E. coli tRNA(Pro) and determined that major groove functional groups at A73 and G72 are critical for recognition by ProRS. Human tRNA(Pro), which lacks these elements, is not aminoacylated by the bacterial enzyme. An analysis of chimeric tRNA(Pro) constructs showed that, in addition to A73 and G72, transplantation of the E. coli tRNA(Pro) D-domain was necessary and sufficient to convert the human tRNA into a substrate for the bacterial synthetase. In contrast to the bacterial system, base-specific acceptor stem recognition does not appear to be used by human ProRS. Alanine-scanning mutagenesis revealed that motif 2 loop residues are not critical for tRNA aminoacylation activity of the human enzyme. Taken together, our results illustrate how synthetases and tRNAs have coadapted to changes in protein-acceptor stem recognition through evolution.

Adaptation, Biological↗

PubMed2000

Leaf flavonoids as systematic characters in the genera Lavandula and Sabaudia.

A comprehensive survey of the leaf flavonoids of the genus Lavandula and the related Sabaudia group was carried out using two-dimensional paper chromatography and high-performance liquid chromatography. The flavonoid patterns obtained were found to be systematically informative at the infrageneric level. Three main groupings were identified: the first containing sections Lavandula, Dentata and Stoechas characterised by the accumulation of flavone 7-glycosides; the second containing sections Pterostoechas, Subnuda and Chaetostachys characterised by the accumulation of 8-hydroxylated flavone 7-and 8-glycosides; the third encompassing the Sabaudia group and accumulating both flavone and 8-hydroxylated flavone 7- glycosides. Such a grouping of taxa is congruent with data from other disciplines, although it is not recognised in any present classifications. The taxonomic and evolutionary implications of the flavonoid data are discussed.

Journal Article↗

PubMed2000

Carboxyl-terminal fragments of Alzheimer beta-amyloid precursor protein accumulate in restricted and unpredicted intracellular compartments in presenilin 1-deficient cells.

Absence of functional presenilin 1 (PS1) protein leads to loss of gamma-secretase cleavage of the amyloid precursor protein (betaAPP), resulting in a dramatic reduction in amyloid beta peptide (Abeta) production and accumulation of alpha- or beta-secretase-cleaved COOH-terminal fragments of betaAPP (alpha- or beta-CTFs). The major COOH-terminal fragment (CTF) in brain was identified as betaAPP-CTF-(11-98), which is consistent with the observation that cultured neurons generate primarily Abeta-(11-40). In PS1(-/-) murine neurons and fibroblasts expressing the loss-of-function PS1(D385A) mutant, CTFs accumulated in the endoplasmic reticulum, Golgi, and lysosomes, but not late endosomes. There were some subtle differences in the subcellular distribution of CTFs in PS1(-/-) neurons as compared with PS1(D385A) mutant fibroblasts. However, there was no obvious redistribution of full-length betaAPP or of markers of other organelles in either mutant. Blockade of endoplasmic reticulum-to-Golgi trafficking indicated that in PS1(-/-) neurons (as in normal cells) trafficking of betaAPP to the Golgi compartment is necessary before alpha- and beta-secretase cleavages occur. Thus, although we cannot exclude a specific role for PS1 in trafficking of CTFs, these data argue against a major role in general protein trafficking. These results are more compatible with a role for PS1 either as the actual gamma-secretase catalytic activity or in other functions indirectly related to gamma-secretase catalysis (e.g. an activator of gamma-secretase, a substrate adaptor for gamma-secretase, or delivery of gamma-secretase to betaAPP-containing compartments).

Alzheimer Disease↗

PubMed2000

Mutation of the conserved N-terminal cysteine (Cys92) of human presenilin 1 causes increased A beta42 secretion in mammalian cells but impaired Notch/lin-12 signalling in C. elegans.

The presenilin proteins are involved in the proteolytic processing of transmembrane proteins such as Notch/lin-12 and the beta-amyloid precursor protein (betaAPP). Mutation of a conserved cysteine (Cys60Ser) in the C. elegans presenilin sel-12 has a loss-of-function effect on Notch/lin-12 processing similar to that of null mutations in sel-12. In contrast, in mammalian cells, most missense mutations increase gamma-secretase cleavage of betaAPP. We report here that mutation of this conserved cysteine (Cys92Ser) in human presenilin 1 confers a loss-of-function effect in C. elegans, but causes increased A beta42 secretion in mammalian cells. These data suggest that the role of presenilins in Notch/lin-12 signalling and betaAPP processing are either separately regulated activities or independent activities of the presenilins.

Amyloid beta-Peptides↗

PubMed2000

Determination of vitamin B12 in multivitamin tablets and fermentation medium by high-performance liquid chromatography with fluorescence detection.

A novel method for the determination of vitamin B12 by high-performance liquid chromatography with fluorescence detection is reported. The method was simple and highly sensitive with good precision. Vitamin B12 was analyzed by HPLC on a muBondapak C18 column (300x3.9 mm, 10 microm) with methanol-water (30:70) as mobile phase and fluorescence detection at 305 nm (with excitation at 275 nm). The calibration graph was linear from 1.000 to 100.0 ng ml(-1) for vitamin B12 with a correlation coefficient of 0.998 (n=6). The detection limit was 0.1 ng ml(-1). The method was successfully applied to the determination of vitamin B12 in vitamin B12 tablets, multivitamin tablets and fermentation medium. The recovery was from 94 to 102% and the relative standard deviation was in the range of 1.8 to 4.1%.

Chromatography, High Pressure Liquid↗