Biomedical subjects

Feng Chen

Publications and source records attributed to Feng Chen.

At least 91 records · Page 5Linked to original sources

PubMed2006

[Thyroid malignant tumor with flare up glottic paralysis for first symptom].

OBJECTIVE: To approach clinical feature of thyroid malignant tumor with Flare up glottic paralysis for first symptom, and analysis that should be avoided missed diagnosis and misdiagnosis during diagnosis and treatment. METHOD: Retrospective research five cases of thyroid malignant tumor with flare up glottic paralysis papillary adenocarcinoma of thyroid by pathology. Four cases had one side glottic paralysis, the same side thyroid were moved after dissecting the recurrent laryngeal nerve. Three cases of them recovered normal vocal cord function, the function of one case was compensated by another side vocal cord. The last one had right gliotic paralysis first, then both cricoarytenoid joint had been fixed, hoarse voice was worse and developed to dyspnea since the tumor invaded in larynx one year later. We only did cut the right thyroid and right half larynx, but the tumor came back again in larynx in three months, then had to removal whole larynx without recurrence follow up two years. CONCLUSION: For the flare up glottic paralysis with same side tiny thyroid tumor, we suggest that the thyroid must be made operation research if no other reasons, dissecting and protecting the recurrent laryngeal nerve during operation, and cut reasonable thyroid and others according to fast pathologic diagnosis.

Carcinoma, Papillary↗

PubMed2006

[Echocardiographic changes and anticardiolipin antibodies in patients with systemic lupus erythematosus].

OBJECTIVE: To analyze the echocardiographic abnormalities and the prevalence of anticardiolipin antibodies (aCL) in systemic lupus erythematosus (SLE) patients and to evaluate the relationship between aCL and cardiac valvular abnormalities in SLE patients. METHODS: Ninety SLE patients were performed M-mode, 2-dimensional and Doppler echocardiography and aCL IgG and IgM were measured by an enzyme-linked immunosorbent assay (ELISA). According to the abnormalities in the echocardiography, the patients were assigned into valvular abnormality group and non-valvular abnormality group. Chi-square method was used to compare the difference of aCL prevalence between the two groups. RESULTS: The prevalence of echocardiographic abnormalities was 53.33%, and valvular abnormality (38.89%) and pericardial effusion (34.44%) presented most frequently. The aCL prevalence was 32.56% in the 43 SLE patients. The prevalence of aCL in the valvular abnormality group was significantly higher than that in non-valvular abnormality group (52.94% vs 19.23%, P<0.05). CONCLUSION: The incidence of echocardiographic abnormalities is high in SLE patients, most often in valves and pericardium. The aCL is probably related to valvular damage in SLE patients.

Adolescent↗

PubMed2006

[The value of thoracoscopy for diagnosis and management of refractory hepatic hydrothorax].

OBJECTIVE: To study the value of thoracoscopy for diagnosis and management of refractory hepatic hydrothorax (HH). METHODS: Twenty-six patients with refractory HH were enrolled in this study. Twenty-four of them underwent therapeutic thoracoscopy to achieve pleurodesis by application of talc poudrage. RESULTS: Nineteen of the 26 patients had dilated chest wall veins, 6 had dilated azygos veins, and 16 had diaphragm blebs. Of the 24 patients who received pleurodesis via thoracoscope, 14 cases showed complete response, and 8 showed partial response. Mild chest pain and temperature elevation were the most complaints during or after the procedure. Liver function abnormalities were the most serious side effects after pleurodesis. During the follow-up period ranging from 6 months to 3 years, 1 patient died of upper gastrointestinal hemorrhage and encephalopathy in 1 month, 3 patients died of hemorrhage in 6, 12, 18 months respectively, and 1 case experienced recurrence in 18 months. CONCLUSIONS: Defects in the diaphragm seemed to be the main cause for the development of HH. Pleurodesis achieved by thoracoscopy and talc poudrage was effective in the treatment of HH, but complications and impaired liver functions should be considered.

Adult↗

PubMed2006

[Effects of short-term high temperature stress on flag leaf photosystem II functions of high-yielding wheat at late grain-filling stage].

By using fast OJIP chlorophyll a ( Chl a) fluorescence transients, this paper studied the effects of short-term high temperature stress on the flag leaf photosystem II (PS II ) functions of high-yielding winter wheat cultivar 01-35 at its late grain filling stage. The results showed that with the temperature raised from 37 degrees C to 43 degrees C , the extent and velocity of QA reduction enhanced gradually, being 23. 89% and 24. 09% higher at 43 degrees C than at room temperature, respectively, which suggested that the electron transport from QA to QB was inhibited. The electron acceptor pool of PS 1I including QA Q, and PQ at 43 degreesC decreased to 47. 4% of that at room temperature, indicating its being damaged. The electron donor side of PS II was not damaged from 37 degrees C to 43 degrees C. When temperature raised to 46 degrees C , the extent and velocity of QA reduction were 13. 95% and 20. 48% higher than those at room temperature, respectively, but decreased obviously, compared with those at 43 degrees C. In contrast, the electron acceptor pool of PS II at 46 degrees C had no obvious change, compared with that at 43 degrees C, indicating that the electron donor side of PS II at 46 TC was damaged. Comparing with cultivar Lumai 14, the light harvesting complex ( LHC U) of high-yielding wheat cultivar 01-35 could harvest more sun energy, and distributed more absorbed energy into electron transport, suggesting that the LHC II of cultivar 01-35 could endure a certain higher temperature, and maintain higher electron transport capacity.

Edible Grain↗

PubMed2005

The differentiation-dependent desmosomal cadherin desmoglein 1 is a novel caspase-3 target that regulates apoptosis in keratinocytes.

Although a number of cell adhesion proteins have been identified as caspase substrates, the potential role of differentiation-specific desmosomal cadherins during apoptosis has not been examined. Here, we demonstrate that UV-induced caspase cleavage of the human desmoglein 1 cytoplasmic tail results in distinct 17- and 140- kDa products, whereas metalloproteinase-dependent shedding of the extracellular adhesion domain generates a 75-kDa product. In vitro studies identify caspase-3 as the preferred enzyme that cleaves desmoglein 1 within its unique repeating unit domain at aspartic acid 888, part of a consensus sequence not conserved among the other desmosomal cadherins. Apoptotic processing leads to decreased cell surface expression of desmoglein 1 and re-localization of its C terminus diffusely throughout the cytoplasm over a time course comparable with the processing of other desmosomal proteins and cytoplasmic keratins. Importantly, whereas classic cadherins have been reported to promote cell survival, short hairpin RNA-mediated suppression of desmoglein 1 in differentiated keratinocytes protected cells from UV-induced apoptosis. Collectively, our results identify desmoglein 1 as a novel caspase and metalloproteinase substrate whose cleavage likely contributes to the dismantling of desmosomes during keratinocyte apoptosis and also reveal desmoglein 1 as a previously unrecognized regulator of apoptosis in keratinocytes.

Apoptosis↗

PubMed2005

Active immunization trial in Abeta42-injected P301L tau transgenic mice.

Amyloid beta-peptide (Abeta) containing plaques and neurofibrillary tangles (NFT) are the two major histopathological hallmarks of Alzheimer's disease (AD). According to the amyloid cascade hypothesis, deposition of Abeta is an initial and essential step in the pathogenesis of AD, and formation of NFT has been proposed to be caused by increased Abeta levels. Several previous studies revealed that Abeta plaque formation can be reduced or even prevented by active immunization with Abeta preparations or by administration of Abeta-specific antibodies. To assess the role of fibrillar preparations of Abeta42 in NFT formation, we previously performed intracerebral (i.c.) injections of Abeta42 into brains of NFT-forming P301L tau transgenic mice which caused significant increases in NFT numbers. To determine whether these increases in NFT can be blocked or reduced by active immunization, P301L tau mice were immunized with intraperitoneal injections of preaggregated Abeta42. Abeta42-specific titers were monitored and the mice injected i.c. with Abeta42. We found that i.c. injection of Abeta42 caused significant increases in NFT formation. However, this induction was not affected by active immunization despite high serum anti-Abeta42 titer levels and binding of anti-Abeta42 antibodies to the injected Abeta42 aggregates. We conclude that active immunization is not sufficient to prevent the effect of Abeta42 on tau aggregation in our model system. Further studies are required to determine whether modifications of our protocol could affect the Abeta42-mediated induction of NFT formation.

Alzheimer Disease↗

PubMed2005

Determination of paralytic shellfish poisoning toxins in cultured microalgae by high-performance liquid chromatography with fluorescence detection.

A novel method for the determination of paralytic shellfish poisoning (PSP) toxins using high-performance liquid chromatography with fluorescence detection was developed. The fluorescent derivates of neosaxitoxin (neoSTX), saxitoxin (STX), gonyautoxins 1 and 4 (GTX1+4), and gonyautoxins 2 and 3 (GTX2+3) were separated on a muBondapak NH2 column (300 mm x 3.9 mm, 10 microm) using water and acetate buffer (pH 6.5) as the mobile phase (1.00 mL min(-1)) in gradient mode with fluorescence detection at 390 nm (excitation at 330 nm). The linear ranges of neoSTX, STX, GTX1+4 and GTX2+3 were 3.31-331, 0.952-95.2, 3.78-378 and 0.124-12.4 ng mL(-1), respectively. The detection limits of neoSTX, STX, GTX1+4 and GTX2+3 were 1.10, 0.32, 1.26 and 0.041 ng mL(-1), respectively. The method was successfully applied to the determination of PSP toxins in microalgae. The recoveries ranged from 88+/-2% to 107+/-4% and the relative standard deviations were 0.16% to 4.4%. The procedure is also environmentally friendly because no organic solvent is used in the mobile phase.

Amides↗

PubMed2005

Determination of vitamin B1 in seawater and microalgal fermentation media by high-performance liquid chromatography with fluorescence detection.

A highly sensitive high-performance liquid chromatographic method with fluorescence detection has been developed for determination of vitamin B(1). Vitamin B(1) was converted into a fluorescent compound by treatment with hydrogen peroxide-horseradish peroxidase and the derivative was subsequently analyzed by HPLC on a Waters Spherisorb ODS2 column (250 mm x 4.6 mm ID, 5 microm) with 40:60 methanol-pH 8.5 acetate buffer solution as mobile phase and fluorescence detection at 440 nm (with excitation at 375 nm). The calibration graph was linear from 5.00 x 10(-10) mol L(-1) to 5.00 x 10(-7) mol L(-1) for vitamin B1 with a correlation coefficient of 0.9991 (n = 9). The detection limit was 1.0 x 10(-10) mol L(-1). The method was successfully used for determination of vitamin B1 at pg mL(-1) levels in microalgal fermentation media and seawater after solid-phase extraction. Recovery was from 89 to 110% and the relative standard deviation was in the range 1.1 to 4.3%.

Chromatography, High Pressure Liquid↗

PubMed2005

Stress-related differential expression of multiple beta-carotene ketolase genes in the unicellular green alga Haematococcus pluvialis.

The unicellular green alga Haematococcus pluvialis is used as a biological production system for astaxanthin. It accumulates large amounts of this commercially interesting ketocarotenoid under a variety of environmental stresses. Here we report the identification and expression of three different beta-carotene ketolase genes (bkt) that are involved in the biosynthesis of astaxanthin in a single strain of the alga. Bkt1 and bkt2 proved to be the crtO and bkt previously isolated from two different strains of H. pluvialis. Bkt3 is a novel third gene, which shared 95% identical nucleotide sequence with bkt2. Nitrogen deficiency alone could not induce the alga cells to produce astaxanthin in 3 days even though it enhances the expression of the bkt genes to three times of that in normal growing cells within 16 h. High light irradiation (125 micromol m(-2)s(-1)) or 45 mM sodium acetate greatly increased the expression of bkt genes to 18 or 52 times of that in normal growing cells, resulting in an accumulation of substantial astaxanthin (about 6 mg g(-1) dry biomass) in 3 days. It is suggested that the existence of the multiple bkt genes and their strong up-regulation by different stress conditions is one of the reasons that H. pluvialis accumulates large amounts of astaxanthin in an instant response to stress environments.

Base Sequence↗

PubMed2005

Isolation and characterization of a carotenoid oxygenase gene from Chlorella zofingiensis (Chlorophyta).

The green alga Chlorella zofingiensis produces large amounts of the valuable ketocarotenoid astaxanthin under dark, heterotrophic growth conditions, making it potentially employable for commercial production of astaxanthin as feed additives, colorants, and health products. Here, we report the identification and characterization of a beta-carotene oxygenase (CRTO) gene that is directly involved in the biosynthesis of ketocarotenoids in C. zofingiensis. The open reading frame of the crtO gene, which is interrupted by three introns of 243, 318, and 351 bp, respectively, encodes a polypeptide of 312 amino acid residues. Only one crtO gene was detected in the genome of C. zofingiensis. Furthermore, the expression of the crtO gene was transiently up-regulated upon glucose treatment. Functional complementation in Escherichia coli showed that the coding protein of the crtO gene not only exhibits normal CRTO activity by converting beta-carotene to canthaxanthin via echinenone, but also displays a high enzymatic activity of converting zeaxanthin to astaxanthin via adonixanthin. Based on the bifunctional CRTO, a predicted pathway for astaxanthin biosynthesis in C. zofingiensis is described, and the CRTO is termed as carotenoid 4,4'-beta-ionone ring oxygenase.

Blotting, Southern↗

PubMed2005

Evaluation of antioxidant activity of vetiver (Vetiveria zizanioides L.) oil and identification of its antioxidant constituents.

Antioxidant capacities of vetiver (Vetiveria zizanioides) oil were evaluated by two different in vitro assays: the DPPH* free radical scavenging assay and the Fe2+-metal chelating assay. Results showed that the vetiver oil (VO) possessed a strong free radical scavenging activity when compared to standard antioxidants such as butylated hydroxytoluene (BHT) and alpha-tocopherol. However, its metal chelating capacity was relatively weak. VO (10 microL/mL) dissolved in methanol exhibited approximately 93% free radical scavenging activity in the DPPH* assay and approximately 34% Fe2+ chelating activity in the metal chelating assay. By contrast, 10 mM BHT and 0.1 mM alpha-tocopherol exhibited 93 and 89% free radical scavenging activities in the DPPH* assay, respectively, and 1 mM EDTA exhibited approximately 97% activity in the metal chelating assay. Among the complex constituents in the crude VO, beta-vetivenene, beta-vetivone, and alpha-vetivone, which had shown strong antioxidant activities, were isolated and identified using various chromatographic techniques including silica gel open column chromatography, silica HPLC, and GC-MS. These results show that VO and some of its inherent components can be potential alternative natural antioxidants.

Antioxidants↗

PubMed2005

Effect of vascular targeting agent in rat tumor model: dynamic contrast-enhanced versus diffusion-weighted MR imaging.

PURPOSE: To compare dynamic contrast material-enhanced magnetic resonance (MR) imaging and diffusion-weighted MR imaging for noninvasive evaluation of early and late effects of a vascular targeting agent in a rat tumor model. MATERIALS AND METHODS: The study protocol was approved by the local ethics committee for animal care and use. Thirteen rats with one rhabdomyosarcoma in each flank (26 tumors) underwent dynamic contrast-enhanced imaging and diffusion-weighted echo-planar imaging in a 1.5-T MR unit before intraperitoneal injection of combretastatin A4 phosphate and at early (1 and 6 hours) and later (2 and 9 days) follow-up examinations after the injection. Histopathologic examination was performed at each time point. The apparent diffusion coefficient (ADC) of each tumor was calculated separately on the basis of diffusion-weighted images obtained with low b gradient values (ADC(low); b = 0, 50, and 100 sec/mm(2)) and high b gradient values (ADC(high); b = 500, 750, and 1000 sec/mm(2)). The difference between ADC(low) and ADC(high) was used as a surrogate measure of tissue perfusion (ADC(low) - ADC(high) = ADC(perf)). From the dynamic contrast-enhanced MR images, the volume transfer constant k and the initial slope of the contrast enhancement-time curve were calculated. For statistical analyses, a paired two-tailed Student t test and linear regression analysis were used. RESULTS: Early after administration of combretastatin, all perfusion-related parameters (k, initial slope, and ADC(perf)) decreased significantly (P < .001); at 9 days after combretastatin administration, they increased significantly (P < .001). Changes in ADC(perf) were correlated with changes in k (R(2) = 0.46, P < .001) and the initial slope (R(2) = 0.67, P < .001). CONCLUSION: Both dynamic contrast-enhanced MR imaging and diffusion-weighted MR imaging allow monitoring of perfusion changes induced by vascular targeting agents in tumors. Diffusion-weighted imaging provides additional information about intratumoral cell viability versus necrosis after administration of combretastatin.

Animals↗

PubMed2005

[Screening of a hepatic stellate cells subtracted cDNA library of differentially expressed genes in mice with schistosomiasis japonica].

OBJECTIVE: To construct and screen a hepatic stellate cells(HSCs) subtracted cDNA library, in order to seek differentially expressed genes in mice infected with Schistosoma japonicum. METHODS: HSCs were isolated from mouse as targets, and cDNA fragments of normal mouse were compared to those of S. japonicum infected mice to find dif ferentially expressed genes by technique of suppression subtractive hybridization(SSH). Differentially expressed cDNA fragments were then directly inserted into T/A cloning vector to set up the subtractive library. Amplification of the library was carried out with transformation of DH5alpha. A subtracted cDNA library was constructed and then hybridized with forward and backward subtracted probes for differential screening. One hundred positive bacterial clones were randomly selected for se quenching and BLAST analysis. Finally, virtual Northern blot confirmed such differential expression. RESULTS: The amplified library contained more than 400 positive bacterial clones. Random analysis of 100 clones with restriction enzyme digestion showed that all clones contained 200-600 bp inserts. 76 ESTs were obtained with 70 related to fibrosis caused by schistosomiasis or other etiological factors. Other 6 ESTs were not found in PubMed. CONCLUSION: The subtracted cDNA library of differentially expressed genes of HSC in normal mice and schistosome-infected mice was constructed successfully with SSH and T/A cloning techniques.

Animals↗

PubMed2005

An Arabidopsis thaliana methyltransferase capable of methylating farnesoic acid.

We previously reported the identification of a new family of plant methyltransferases (MTs), named the SABATH family, that use S-adenosyl-L-methionine (SAM) to methylate a carboxyl moiety or a nitrogen-containing functional group on a diverse array of plant compounds. The Arabidopsis genome alone contains 24 distinct SABATH genes. To identify the catalytic specificities of members of this protein family in Arabidopsis, we screened recombinantly expressed and purified enzymes with a large number of potential substrates. Here,we report that the Arabidopsis thaliana gene At3g44860 encodes a protein with high catalytic specificity towards farnesoic acid (FA). Under steady-state conditions, this farnesoic acid carboxyl methyltransferase (FAMT) exhibits KM values of 41 and 71 microM for FA and SAM, respectively. A three-dimensional model of FAMT constructed based upon similarity to the experimentally determined structure of Clarkia breweri salicylic acid methyltransferase (SAMT) suggests a reasonable model for FA recognition in the FAMT active site. In planta, the mRNA levels of At3g44860 increase in response to the exogenous addition of several compounds previously shown to induce plant defense responses at the transcriptional level. Although methyl farnesoate (MeFA) has not yet been detected in Arabidopsis, the presence of a FA-specific carboxyl methyltransferase in Arabidopsis capable of producing MeFA, an insect juvenile hormone made by some plants as a presumed defense against insect herbivory, suggests that MeFA or chemically similar compounds are likely to serve as new specialized metabolites in Arabidopsis.

Amino Acid Sequence↗

PubMed2005

Value of CT and clinical criteria in assessment of patients with acute pancreatitis.

OBJECTIVE: To re-assess the value of CT and clinical criteria as prognostic and severity indicators in acute pancreatitis and the correlation between them. METHODS: Sixty-five cases with acute pancreatitis (AP) were included in the study. The hospitalization days, fevering days and overall complications were regarded as clinical endpoints for the patient group. CT criteria used for AP evaluation included Balthazar's plain CT scan score, CT severity index (CTSI) and London's pancreatic size index (PSI) score. Clinical criteria was Ranson score. The correlations between each criterion and the clinical endpoints, and the relation between CT and clinical criteria were analyzed. The power of each criterion and combination of CT and clinical criteria in predicting overall complications of AP were assessed and compared by using a receiver operative characteristic curve (ROC) analysis. RESULTS: The mean scores of PSI, Ranson among the three groups classified according to overall complications were significantly different. Except Balthazar's plain CT scan criterion, each criterion's mean score in-groups with local complications was significantly higher than that in-group without. The overall complications were significantly more in severe group than that in mild group classified according to each criterion except plain CT scan criterion. Mean days of hospital stay and fevering were significantly longer in severe group with Ranson score than that in mild group. PSI and Ranson score had a linear correlation with fevering days, and Ranson score had a linear correlation with hospitalization days. In CT criteria, only PSI had a linear correlation with Ranson score. The findings of plain CT scan was found to be some laggard compared with that of clinic. ROC analysis showed the largest A(Z) of Ranson score, and there was no A(Z) increase when CT criteria were added to clinical criteria. CONCLUSION: The predictive values of Ranson and PSI score in AP patients are superior to that of other criteria. CT criteria are superior to clinical criterion in predicting local complications, and short-term CT follow-up examination is important in the evaluation of AP.

Acute Disease↗

PubMed2005

Metaproteomic analysis of Chesapeake Bay microbial communities.

BACKGROUND: Natural microbial communities are extremely complex and dynamic systems in terms of their population structure and functions. However, little is known about the in situ functions of the microbial communities. RESULTS: This study describes the application of proteomic approaches (metaproteomics) to observe expressed protein profiles of natural microbial communities (metaproteomes). The technique was validated using a constructed community and subsequently used to analyze Chesapeake Bay microbial community (0.2 to 3.0 microm) metaproteomes. Chesapeake Bay metaproteomes contained proteins from pI 4-8 with apparent molecular masses between 10-80 kDa. Replicated middle Bay metaproteomes shared approximately 92% of all detected spots, but only shared 30% and 70% of common protein spots with upper and lower Bay metaproteomes. MALDI-TOF analysis of highly expressed proteins produced no significant matches to known proteins. Three Chesapeake Bay proteins were tentatively identified by LC-MS/MS sequencing coupled with MS-BLAST searching. The proteins identified were of marine microbial origin and correlated with abundant Chesapeake Bay microbial lineages, Bacteroides and alpha-proteobacteria. CONCLUSION: Our results represent the first metaproteomic study of aquatic microbial assemblages and demonstrate the potential of metaproteomic approaches to link metagenomic data, taxonomic diversity, functional diversity and biological processes in natural environments.

Journal Article↗

PubMed2005

Stress distribution and dimensional changes in chromatographic columns.

High pressures, in the kilobar range, are now used in liquid chromatography. Basic equations from mechanics are applied to investigate the stress state in several idealized chromatography tubes, and these stresses are evaluated with respect to the maximum allowable stresses predicted by several methods used in pressure vessel design. An analytical solution is developed for the dimensional changes of idealized tubes subjected to internal pressure, and the analytical solutions used to verify the results from a numerical approximation. Numerical approximations are then used to explore the effects of the end restraint provided by the end frits. Conclusions are derived regarding the requirements for a safe operation of these high pressure chromatography tubes.

Chromatography↗

PubMed2005

Preparative isolation and purification of phillyrin from the medicinal plant Forsythia suspensa by high-speed counter-current chromatography.

Forsythia suspensa (Thunb.) Vahl. has been used widely in traditional medicines to treat gonorrhea, erysipelas, inflammation, pyrexia and ulcer. It has also shown antioxidant activity, as well as antibacterial, antiviral, choleretic and antiemetic effects. A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of the bioactive molecule phillyrin from F. suspensa (Thunb.) Vahl. The crude phillyrin was obtained by extraction with 50% ethanol from the dried fruits of F. suspensa (Thunb.) Vahl. under sonication. Preparative HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (1:9:1:9, v/v/v/v) was successfully performed, and the components purified and collected were analyzed by high-performance liquid chromatography. The method yielded 5.6 mg phillyrin at 98.6% purity from 500 mg of the crude extract (1.2% phillyrin) with the recovery of 92% in a one-step separation.

Chromatography, High Pressure Liquid↗