Biomedical subjects

Fang Chen

Publications and source records attributed to Fang Chen.

At least 73 records · Page 4Linked to original sources

PubMed2005

[Effects of continuous cropping on understorey species diversity in Eucalypt plantations].

By the methods of time-space series analysis and field monitoring, this paper studied the species diversity and its maintaining mechanism in Dongmen Eucalypt plantations of Guangxi. The results indicated that during the period of 1998 - 2003, continuous cropping of Eucalyptus plantation resulted in a reduction of species diversity. The plant species number of second generation was reduced by 54.43% in a 667 m2 plot, and by 50% in 18 sampling plots (each of 4 m2), and the species richness and Shannon-Wiener index of 6-year second generation forest decreased by 39.39% and 17.76%, respectively, compared with the first generation. The continuous cropping not only decreased the species diversity, but also changed the species composition and characteristics of the community. Life-form spectra of Eucalypt plantations varied with generation. The plant life-form consisted of microphanerophytes, liana phanerophytes, and nana-phanerophytes in the first generation, while the herbaceous-phanerophytes and chamaephytes occurred in the second generation. The k-strategy and r-strategy species accounted for 69.32% and 30.68% in the first generation, while 47.83% and 52.17% in the second generation, respectively. Therefore, continuous cropping of Eucalypt plantations was advantage for herb, therophytes and r-strategy species, but disadvantage for woody plants and k-strategy species. Seed band and vegetative body in soil were considered to play an important role in maintaining diversity. A new hypothesis, initial plant Diaspora, on the maintaining mechanism of species diversity in Eucalypt plantation was put forward.

Biodiversity↗

PubMed2005

[A comparative study on feeding intensity of two rotifer Brachionus calyciflorus strains].

The study on the feeding intensity and its relationships with food concentration, food quality and cultural duration of Guangzhou and Wuhu Brachionus calyciflorus strains showed that the filtration and ingestion rates of the rotifers decreased with their increasing cultural duration. Within 20 hours, there was a curvilinear relationship between the filtration rate of both the two strains and food concentration, but a linear relationship between the ingestion rate and food concentration. The filtration rate of Guangzhou and Wuhu strains was 0.0029 +/- 0.0001 ml x ind. (-1) x h(-1) and 0.0039 +/- 0.0008 ml ind. (-1) x h(-1), respectively, when fed on Chlorella pyrenoidosa, which were higher than fed on the other two types of food. The ingestion rate of Guangzhou strain fed on Chlorella pyrenoidosa (0.3992 x 10(4) +/- 0.00850 x 10(4) cell ind. (-1) x h(-1)) was higher than that fed on Scenedesmus obliquus (0.1670 x 10(4) +/- 0.0370 x 10(4) cell x ind.(-1) x h(-1)), but each of them was similar with that on mixed algae. The ingestion rate of Wuhu strain was not significantly affected by food type. The filtration and ingestion rates between the two strains differed with food concentration, food type and culture duration.

Animals↗

PubMed2004

The LATS2/KPM tumor suppressor is a negative regulator of the androgen receptor.

The androgen receptor (AR) is a member of the steroid receptor superfamily that plays critical roles in the development and maintenance of the male reproductive system and in prostate cancer. Actions of AR are controlled by interaction with several classes of coregulators. In this study, we have identified LATS2/KPM as a novel AR-interacting protein. Human LATS1 and LATS2 are tumor suppressors that are homologs of Drosophila warts/lats. The interaction surface of LATS2 is mapped to the central region of the protein, whereas the AR ligand binding domain is sufficient for this interaction. LATS2 functions as a modulator of AR by inhibiting androgen-regulated gene expression. The mechanism of LATS2-mediated repression of AR activity appears to involve the inhibition of AR NH2- and COOH-terminal interaction. Chromatin immunoprecipitation assays in human prostate carcinoma cells reveal that LATS2 and AR are present in the protein complex that binds at the promoter and enhancer regions of prostate-specific antigen, and overexpression of LATS2 results in a reduction in androgen-induced expression of endogenous prostate-specific antigen mRNA. Immunohistochemistry shows that LATS2 and AR are localized within the prostate epithelium and that LATS2 expression is lower in human prostate tumor samples than in normal prostate. The results suggest that LATS2 may play a role in AR-mediated transcription and contribute to the development of prostate cancer.

Androgen Receptor Antagonists↗

PubMed2004

[Expression of human fibrinogen-like protein 2/fibroleukin in renal acute allograft rejection and its potential clinical implication].

OBJECTIVE: To investigate the expression of human fibrinogen-like protein 2 (hfgl2)/fibroleukin in renal acute allograft rejection and its correlation with the course of the disease. METHODS: Thirty-one samples of aspiration biopsy of renal acute allograft rejection were collected. Histological sections were stained with hemotoxylin and eosin. Polyclonal antibody against hfgl2 was used to detect the expression of hfgl2 protein by immunohistochemistry. Anti-CD68 and anti-CD8 monoclonal antibodies were used to detect the macrophages activation and lymphocyte respectively in serial sections to identify the cell types that express hfgl2. Anti-fibrinogen monoclonal antibody and thrombus staining were used to detect the fibrin deposition and the formation of thrombus. Double staining with anti-hfgl2 antibody and anti-fibrinogen antibody was performed to clarify the correlation between hfgl2 expression and fibrin deposition. RESULTS: Twenty-nine cases showed hfgl2 expression, mainly displayed in tubule cells, infiltrative cells (macrophages, CD8+ T cells and plasmacytes), and part of the adherent cells or infiltrative cells in tubules and vessels, whereas no hfgl2 protein was detected in glomerulus and endothelium of vessels. Double staining displayed that the fibrin deposition was mainly in the vessels, glomeruli and interstitium, and the lumen of tubule in association with hfgl2 expression. No thrombus was found in all the sections. CONCLUSION: The abnormal expression of hfgl2 in renal acute allograft rejection in human beings activates the thrombosin inside and outside the vessels that causes fibrin deposition and microcirculatory disturbances, thus further exacerbating the pathological injuries of tissues. hfgl2 protein may serve as a new target for therapeutic intervention for acute allograft rejection.

Acute Disease↗

PubMed2004

The behavior of deuterium-labeled monolignol and monolignol glucosides in lignin biosynthesis in angiosperms.

To examine the behavior of monolignol and monolignol glucosides in lignin biosynthesis, pentadeutero[9-D(2), 3-OCD(3)]coniferyl alcohol and pentadeutero[9-D(2), 3-OCD(3)]coniferin were synthesized and fed to growing Eucalyptus camaldulensis and Magnolia kobus. The differences in the incorporation patterns of these labeled precursors were studied using gas chromatography-mass spectrometry (GC-MS). Both precursors were incorporated into lignin, but the labeled coniferyl alcohol was incorporated more directly, resulting in a high proportion of pentadeutero-labeled guaiacyl and syringyl units in newly formed xylem, while labeled coniferin tended to be incorporated in lignin as tetradeutero units, especially in syringyl lignin in both trees. However, the incorporation efficiencies of the precursors into syringyl lignin were higher in Magnolia than in Eucalyptus, and the ratios of tetradeutero to pentadeutero in guaiacyl lignin were lower in Magnolia than in Eucalyptus when the trees were fed coniferin.

Cinnamates↗

PubMed2004

An optimized gossypol high-performance liquid chromatography assay and its application in evaluation of different gland genotypes of cotton.

A comparative study on gossypol content of various genetic types of pigment glands of cotton varieties was conducted through an optimized high-performance liquid chromatography (HPLC) on a C18 column (4.6 mm x 250 mm, 5 microm particle) with methanol-0.5% acetic acid aqueous solution, 90 : 10 (v/v), as mobile phase, at a flow rate of 0.8 ml/min and UV detection at 254 nm. The method was shown to be highly reproducible, with precision [as relative standard deviation (RSD)] and accuracy [as relative mean error (RME)] < 10%, both intra-day and inter-day. Absolute recoveries were > 94%. The results revealed major differences among the different gland varieties or species of cotton, including the special and ordinary glandless and glanded Gossypium hirsutum, G. barbadense, and displayed the precious resources of different glands of extraordinary cotton.

Calibration↗

PubMed2004

Silencing of hdm2 oncogene by siRNA inhibits p53-dependent human breast cancer.

RNA interference technology is a powerful tool for silencing endogenous or exogenous genes in mammalian cells. Here our results showed that hdm2-siRNA silenced its target mRNA specifically and effectively in human breast cancer cells, reduced tumor cell proliferation and induced apoptotic cell death. Other molecular features modified by hdm2-siRNA included decreased Bcl-2, NF-kappaB, survivin, Ras and Raf levels, elevated p53, p21, BRCA1, Bax, and caspase levels as well as altered expression of other genes. hdm2-siRNA also caused cell cycle arrest at G1 phases with reduction in cyclin and Cdk proteins. In addition, hdm2-siRNA displayed in vivo antitumor activity and increased therapeutic effectiveness of mitomycin in MCF-7 xenografts. Thus, hdm2-siRNA may be a promising gene-specific drug for the treatment of human breast cancer and other tumors.

Apoptosis↗

PubMed2004

[Assessing the transvalvular gradient of a Chinese-made jiuling solid pyrolytic carbon bileaflet heart valve prosthesis].

In order to assess the transvalvular gradient of a Chinese-made Jiuling solid pyrolytic carbon bileaflet heart valve prosthesis, we determined its hydrodynamics in the laboratory and then measured the hemodynamic performance in the animals and patiens. The Jiuling prosthesis was tested in a pulsatile flow simulator in the aortic position. Six sheep subjected to mitral replacement with 21 mm Jiuling prosthesis were measured by open cardiac catheterization intraoperatively. Doppler echocardiography and open cardiac catheterization under dobutamine stress were performed in two sheep 60 months after implantation. Clinically, 14 cases of aortic valve and 10 cases of mitral valve in the patients who underwent valve replacement with Jiuling heart valve prosthesis were measured by open cardiac catheterization and Doppler echocardiopgraphy. The results showed that Juiling heart valve prosthesis had lower mean transvalvular gradient (below 10 mmHg) at any given tissue annulus diameter. In animal experiments, the transvalvular gradients of 6 sheep were 5.2 +/- 1.7 mmHg intraoperatively, and of 2 sheep 60 months after implantation were 6.1 +/- 0.3 mmHg by catheterization. In patients, the mean transvalvular gradients in the aortic position measured by means of catheterization and echocardiography were 6.26-4.10 mmHg and 9.42-7.48 mmHg; the gradients in the mitral position were 2.10-1.9 mmHg and 5.281-4.10 mmHg respectively. The above results demonstrate that Jiuling valve prosthesis has excellent hemodynamic performance.

Adult↗

PubMed2004

[Questionnaire and pad-test in assessment of incontinence after radical retro-pubic prostatectomy].

OBJECTIVE: To confirm urinary incontinence after radical retro-pubic prostatectomy by questionnaire and pad-test, observe the influence of radical prostatectomy on the patient's quality of life (QOL), and study the effect of urethral sphincter preservation and the patient's age on incontinence. METHODS: Questionnaire and pad-test were conducted in 165 consecutive prostate cancer patients who underwent radical prostatectomies. The mean follow-up time was 13 months (12-14 months). Each patient was kept in contact with our incontinence advisor by telephone or direct interview. At 12 months after operation, the patients were asked to the clinic to fill in the questionnaire and underwent the pad-test. In accordance to different operative techniques, the patients were divided into a sphincter repairing group (19 cases) and a sphincter preservation group (146 cases). RESULTS: All the 165 patients were kept in contact with us, underwent the pad-test and filled in the questionnaire. Of the 7 patients diagnosed as incontinence for admitting using pads, only 1 had urinary leakage, and the other 6, who did not use pads very often, showed slight change of QOL. In the pad-test, 5 patients were considered to be incontinent since the pad weight gained > 1 grams. Between the questionnaire and the pad-test there was a high concordant rate (98.8%). Within 3 months after operation, younger patients seemed to return to continence sooner. The continence rate at 12 months after operation was 99.3% in the sphincter preservation group and 94.7% in the sphincter-repairing group. The incontinence rates at the removal of the urinary catheter after operation were 60% and 82% in patients aged 51-60 and 61-70, respectively. At 3 months after operation, the incontinence rates were similar in both groups. CONCLUSION: Both the questionnaire and the pad-test are recommendable in the assessment of post-operative incontinence since it can accurately document patients' incontinent status. Preservation of the urethral sphincter and its possible innervations can improve the incontinence rate. Younger patients seem to return to continence sooner than the elders.

Adult↗

PubMed2004

[Molecular cloning and analysis of a monocot mannose-binding agglutinin from Zephyranthes grandiflora (family Amaryllidaceae)].

The monocot mannose-binding lectin can inhibit HIV from infecting the target cells. The total RNA of Zephyranthes grandiflora was extracted and reversely transcribed into cDNA. Degenerate primers were designed based on the conserved regions of other monocot mannose-binding agglutinins by homology alignment. The 694bp full-length cDNA of Zephyranthes grandiflora agglutinin (ZGA) was cloned by RT-PCR, 3' and 5' RACE (rapid amplification of cDNA ends). The start codon and stop codon of ZGA were at 37-39bp and 529-531bp respectively. The NCBI Blast analysis result showed that ZGA gene encoded a protein precursor with signal peptide, mature protein and C-terminal cleavage sequence. The mature ZGA protein contained 106 amino acids residues and its molecular weight was 11.6KD. The percentages of identity of the deduced mature ZGA protein with those of Galanthus nivalis agglutinin, Narcissus hybrid cultivar agglutinin, Lycoris radiate agglutinin and Clivia miniata agglutinin were 71.8%, 81%, 81.8% and 84.5%, respectively. Blocks analysis revealed that ZGA had three functional domains and three mannose-binding boxes (QDNY).

Agglutinins↗

PubMed2004

Plant regeneration from epicotyl explant of Jatropha curcas.

In vitro epicotyl explants from Jatropha curcas were cultured on MS medium with indole-3-butyric acid (IBA) and 6-benzyladenine (BA). Adventitious buds were directly induced from the surface of epicotyl explants under the condition with the combinations of IBA 0.1 mg/L and BA 0.2-0.7 mg/L. Of which IBA 0.1 mg/L and BA 0.5 mg/L induced the highest regeneration frequency. Shoot regeneration from callus required the combinations of IBA 0.5 mg/L with BA 0.1 mg/L, IBA 0.5 mg/L with BA 0.2 mg/L and IBA 1.0 mg/L with BA 0.5 mg/L, and the most suitable combination was IBA 1.0 mg/L and BA 0.5 mg/L. The health adventitious buds and regenerated shoots could be rooted on growth regulator-free MS medium. Regenerated plants with well developed shoots and roots were successfully transferred to greenhouse, without visible detectable variation.

Adenine↗

PubMed2004

[Determination of crocin-1 in rabbit plasma and the pharmacokinetics by RP-HPLC].

AIM: To develop a sensitive and specific HPLC method for the determination of crocin-1 in rabbit plasma, and study the pharmacokinetics in rabbit. METHODS: After i.v. administration of crocin-1 in rabbit, the sample could be well purified after precipitation of protein with methanol. Waters spherisorb C18 column (250 mm x 4.6 mm ID, 5 microm) was used and the mobile phase consisted of methanol-acetonitrile-1% aqueous acetic acid (15:10:50) at the flow rate of 1 mL x min(-1), and the UV detection wave length was 440 nm. The column temperature is 25 degrees C. RESULTS: The calibration curve was linear (r = 0.9997) in the range from 0.86 to 27.54 mg x L(-1) for crocin-1. The lowest detectable concentration of crocin-1 was 0.42 mg x L(-1). After given i.v. crocin-1 in rabbit, the concentration-time curves of crocin-1 was shown to fit two-compartment open model. CONCLUSION: This method is proved to be rapid, precise and reliable enough to be applied to the pharmacokinetics studies of crocin-1 in rabbit.

Animals↗

PubMed2004

[Effect of temperature and food concentration on the population dynamics of three Brachionus calyciflorus strains].

Effects of temperature (20 degrees C, 25 degrees C, 30 degrees C) and food concentration (1.5, 3.0, 6.0, 9.0 x 10(6) cells x ml(-1)) on the population dynamics of Brachionus calyciflorus of Qingdao, Wuhu and Guangzhou strains were studied by means of individual culture. The result showed that the temperature was an important factor affecting generation time and intrinsic rate of population increase. With rising of temperature, the intrinsic rate of population increase increased, but generation time decreased. There were significant effects of food concentration on life expectancy and average lifespan. The effect of strain on net reproductive rate, generation time, life expectancy and average lifespan was also significant. Net reproductive rate, generation time, life expectancy, and average lifespan of Guangzhou strain was all the maximum, and that of Wuhu strain minimum among the three strains. The rotifers fed on the algae at the concentration of 3.0 x 10(6) cells x ml(-1) had the longest life expectancy and average lifespan, but those at 9.0 x 10(6) cells x ml(-1) had the shortest. Net reproductive rate, generation time, gross reproductive rate, life expectancy, and average lifespan of the three strains decreased linearly with the rise of temperature, except for the net reproductive rate of Guangzhou strain, while the intrinsic rate of population increase of all the three strains and gross reproductive rate of Guangzhou strain increased linearly with the rise of temperature. The relationships between all the life history parameters of Qingdao and Guangzhou strains and food concentration were all curvilinear, however, those between generation time, average lifespan, and life expectancy of Wuhu strain and food concentration could all be described by linear regression.

Animals↗

PubMed2003

Determination of DNA by Rayleigh light scattering enhancement of molecular "light switches".

Base on the enhancement of Rayleigh light scattering signals of molecular "light switches" by DNA under acidic condition, a sensitive and convenient method for DNA determination was proposed. The experiments indicated that, under optimum conditions, good linear relationships were obtained between the Rayleigh light scattering intensity and the concentration of nucleic acids. The detect limits of calf thymus DNA (ctDNA) were 13.0 ng ml(-1), 4.2 ng ml(-1), 51.5 ng ml(-1) and 3.0 ng ml(-1) with four "light switches", respectively. Plasmid DNA extracted from Bacillus subtilis were determined by the proposed method with satisfactory results, and the recovery rates of calf thymus DNA were in the range of 94.6-110.7%.

Animals↗

PubMed2003

[Eosinophilic cystitis in children:a report of six cases and review of literature].

OBJECTIVE: Eosinophilic cystitis is a very rare tumor-like inflammatory disease especially in children. It can involve any portion of the bladder and interfere with its function. Here we present 6 pediatric cases and review the literature. METHODS: Six children, with mean age of 8.3 years, were referred to our clinic. Their major complaints included voiding urgency, frequency, dysuria, enuresis, intermittent hematuria and abdominal pain. Ultrasound, CT scan and voiding cystourethrogram (VCUG) showed diffuse thickening of bladder wall and a filling-defect lesion. They all suggested the possibility of bladder tumor. The final diagnosis of eosinophilic cystitis was made by cystoscopic tissue biopsy or open surgery. Patients underwent bladder autoaugmentation, mass resection or mere oral administration of corticosteroid and antibiotics respectively. RESULTS: 5 among 6 patients were followed up for 5 - 28 months. Their voiding complaints and image changes gradually disappeared. Up to now, there is no relapse. CONCLUSIONS: The clinical presentation of eosinophilic cystitis includes irritative voiding symptoms, hematuria and abdominal pain. Tumor-like changes could be found in the imagination examinations. A biopsy is mandatory to establish the diagnosis. Treatment in general varies from the removal of the antigenic stimulus, if identifiable, to administration of corticosteroid and antibiotics. When patients fail to respond to the medication treatment, the opening operation could be required.

Adolescent↗

PubMed2003

Measurements of the yield and chlorine utilization of singlet oxygen generator by use of Raman spectroscopy.

A Raman scattering system was used to measure the O2 (a1delta) yield end the chlorine utilization in a singlet oxygen generator of chemical oxygen iodine laser with nitrogen diluent. We present the results from the tests that conducted on a 0.1-mol/s jet-type singlet oxygen-iodine generator. On the basis of the current reported uncertainty of the Raman cross section, the error in the yield measurement is calculated to be less than 8%, and the error of the chlorine utilization is 12%.

Journal Article↗

PubMed2003

Structural and compositional modifications in lignin of transgenic alfalfa down-regulated in caffeic acid 3-O-methyltransferase and caffeoyl coenzyme A 3-O-methyltransferase.

Isolated lignins from alfalfa deficient in caffeic acid 3-O-methyltransferase contained benzodioxanes resulting from the incorporation of the novel monomer, 5-hydroxyconiferyl alcohol. Due to the high level incorporated into the soluble lignin fraction and the use of sensitive NMR instrumentation, unique structural features were revealed. A new type of end-unit, the 5-hydroxyguaiacyl glycerol unit, was identified. It was possible to establish that coniferyl alcohol, sinapyl alcohol, and the novel 5-hydroxyconiferyl alcohol can cross-couple with the 5-hydroxyguaiacyl units that are formed in the lignin, the latter giving rise to extended chains of benzodioxane units. There is also evidence that 5-hydroxyconiferyl alcohol couples with normal (guaiacyl or syringyl) lignin units. Lignin in the alfalfa deficient in caffeoyl CoA 3-O-methyltransferase was structurally similar to the control lignin but the transgenic exhibited a dramatic decrease in lignin content (approximately 20%) and modest increase in cellulose (approximately 10%) reflecting a 30% increase in cellulose:lignin ratio. The compositional changes in both transgenics potentially allow enhanced utilization of alfalfa as a major forage crop by increasing the digestibility of its stem fraction.

Down-Regulation↗

PubMed2003

Phenylpropanoid compounds and disease resistance in transgenic tobacco with altered expression of L-phenylalanine ammonia-lyase.

Tobacco plants over-expressing L-phenylalanine ammonia-lyase (PAL(+)) produce high levels of chlorogenic acid (CGA) and exhibit markedly reduced susceptibility to infection with the fungal pathogen Cercospora nicotianae, although their resistance to tobacco mosaic virus (TMV) is unchanged. Levels of the signal molecule salicylic acid (SA) were similar in uninfected PAL(+) and control plants and also following TMV infection. In crosses of PAL(+) tobacco with tobacco harboring the bacterial NahG salicylate hydroxylase gene, progeny harboring both transgenes lost resistance to TMV, indicating that SA is critical for resistance to TMV and that increased production of phenylpropanoid compounds such as CGA cannot substitute for the reduction in SA levels. In contrast, PAL(+)/NahG plants showed strongly reduced susceptibility to Cercospora nicotianae compared to the NahG parent line. These results are consistent with a recent report questioning the role of PAL in SA biosynthesis in Arabidopsis, and highlight the importance of phenylpropanoid compounds such as CGA in plant disease resistance.

Ascomycota↗