Biomedical subjects

Fang Chen

Publications and source records attributed to Fang Chen.

90 records · Page 5Linked to original sources

PubMed2003

Profiling phenolic metabolites in transgenic alfalfa modified in lignin biosynthesis.

Soluble phenolics, wall-bound phenolics and soluble and core lignin were analyzed in transgenic alfalfa with genetically down-regulated O-methyltransferase genes involved in lignin biosynthesis. High performance liquid chromatography and principal component analysis were used to distinguish metabolic phenotypes of different transgenic alfalfa genotypes growing under standard greenhouse conditions. Principal component analysis of HPLC chromatograms did not resolve differences in leaf metabolite profiles between wild-type and transgenic plants of the same genetic background, although stem phenolic profiles were clearly different between wild-type and transgenic plants. However, the analytical methods clearly differentiated two non-transgenic alfalfa cultivars based on either leaf or stem profiles. Metabolic profiling provides a useful approach to monitoring the broader biochemical phenotypes of transgenic plants with altered expression of lignin pathway enzymes.

Cell Wall↗

PubMed2003

Normal value of resting energy expenditure in healthy neonates.

OBJECTIVE: We investigated the value of resting energy expenditure (REE) in healthy neonates and evaluated the impact factors on REE. METHODS: One hundred eighty healthy neonates (95 boys and 85 girls) with birth weights above 2500 g were measured by indirect calorimetry, and the effect of birth weight evaluated. Measured and predicted REEs were compared, and the effects of sex and delivery method on REE were examined in 154 newborn infants with birth weights of approximately 2500 to 4000 g. RESULTS: Birth weight had a significant effect on REE. There was a negative relation between REE and birth weight (r = -0.289). The REEs of newborn infants weighing more than 4000 g were statistically lower than those of infants weighing 2500 to 4000 g (44.5 +/- 5.9 versus 48.3 +/- 6.1 kcal x kg(-1) x d(-1), P = 0.01). The measured and predicted REEs of 154 newborn infants were 48.3 +/- 6.1 and 54.1 +/- 1.1 kcal x kg(-1) x d(-1), respectively. There was a significant difference between the two values. Sex and delivery methods had no effect on REE in healthy neonates. CONCLUSIONS: The value from the predicted equation is not suitable for neonatal energy supplementation in clinical practice. The normal REE value for healthy neonates with birth weights of 2500 to 4000 g is 48.3 +/- 6.1 kcal x kg(-1) x d(-1).

Birth Weight↗

PubMed2003

Improved forage digestibility of tall fescue (Festuca arundinacea) by transgenic down-regulation of cinnamyl alcohol dehydrogenase.

Lignification of cell walls during plant development has been identified as the major factor limiting forage digestibility and concomitantly animal productivity. cDNA sequences encoding a key lignin biosynthetic enzyme, cinnamyl alcohol dehydrogenase (CAD), were cloned from the widely grown monocotyledonous forage species tall fescue (Festuca arundinacea Schreb.). Recombinant tall fescue CAD expressed in E. coli exhibited the highest V(max)/K(m) values when coniferaldehyde and sinapaldehyde were used as substrates. Transgenic tall fescue plants carrying either sense or antisense CAD gene constructs were obtained by microprojectile bombardment of single genotype-derived embryogenic suspension cells. Severely reduced levels of mRNA transcripts and significantly reduced CAD enzymatic activities were found in two transgenic plants carrying sense and antisense CAD transgenes, respectively. These CAD down-regulated transgenic lines had significantly decreased lignin content and altered ratios of syringyl (S) to guaiacyl (G), G to p-hydroxyphenyl (H) and S to H units. No significant changes in cellulose, hemicellulose, neutral sugar composition, p-coumaric acid and ferulic acid levels were observed in the transgenic plants. Increases of in vitro dry matter digestibility of 7.2-9.5% were achieved in the CAD down-regulated lines, thus providing a novel germplasm to be used for the development of grass cultivars with improved forage quality.

Journal Article↗

PubMed2003

Cloning and characterization of a curcin gene encoding a ribosome inactivating protein from Jatropha curcas.

A curcin gene was isolated by using genomic walker technology and revealed to encode the type-1 ribosome inactivating proteins (RIPs). Analysis of 1802 bp segments revealed the gene including a 694 bp 5' flanking region, a 882 bp open read frame (ORF) and a 226 bp 3' flanking region. There are one putative TATA boxes and two possible CAAT box lie in the 5'-flanking region. The ORF encodes a 32 kDa precursor, which contains a 42 amino acid signal peptide. Two possible polyadenylation signals are found in the 3'-flanking region. No introns were found, which is typical of other RIPs gene that has been sequenced. The deduced amino acid sequence of Curcin gene coding region shares high homology with RIPs, e.g. ricin A-chain, gelonin, abrin A-chain, bryodin, trichosanthin and momorcharin, which were found to be 34% (99/287), 34% (98/287), 37% (89/240), 34% (86/249), 36% (87/241) and 36% (88/241), respectively. The cloning of the gene is important foundation to further study the structure, expression and regulation mechanism.

Albumins↗

PubMed2003

Antitumor effects of curcin from seeds of Jatropha curcas.

AIM: To study the antitumor effects of curcin from Jatropha curcas. METHODS: Antitumor activity of curcin was tested by MTT assay. The N-glycosidase activity of curcin was determined by characterization of R-fragment in gel. A cell-free system, rabbit reticulocyte lysate, was introduced to quantify the inhibitory activity of curcin on protein biosynthesis. RESULTS: The curcin had a powerful inhibitory action upon protein synthesis in reticulocyte lysate with an IC50 (95 % confidence limits) value of 0.19 (0.11-0.27) nmol/L. The IC50 (95 % confidence limits) of curcin on SGC-7901, Sp2/0, and human hepatoma was 0.23 (0.15-0.32) mg/L, 0.66 (0.35-0.97) mg/L, 3.16 (2.74-3.58) mg/L, respectively. Curcin was found to have no toxic to Hela cells and normal cells (MRC). After the rRNA of ribosome was treated with curcin and aniline at acidic condition, a cleaved R-fragment of approximately 450 nt appeared, but this fragment did not occur after treatment with curcin only. A comparison of the amino acid sequences of curcin, ricin A-chain and trichosanthin revealed that there were relatively high similarities among them. The percentages of homology between curcin and ricin A chain, between curcin and trichosanthin were found to be 54 % and 57 % respectively. Especially, the conserved residues forming the active sites of the A chain of ricin and trichosanthin occurred in curcin. CONCLUSION: Curcin has an obvious antitumor effect and its mechanisms are related to the N-glycosidase activity.

Amino Acid Sequence↗

PubMed2003

[Analysis of 16 cases of uterine perforation during hysteroscopic electro-surgeries].

OBJECTIVE: To analyse the cause, diagnosis, treatment and preventive methods of uterine perforation resulting from hysteroscopic electro-surgeries. METHODS: Data of cases with uterine perforation were collected from 5 hospitals where overall 3,541 hysteroscopic electro-surgeries were done from May 1990 to July 2002. There were 1 468 transcervical resections of endometrium (TCRE), 797 cases of transcervical resection of myoma (TCRM), 783 cases of transcervical resection of endometrial polyp (TCRP), 189 cases of transcervical resection of uterine septa (TCRS), 112 cases of transcervical resection of uterine adhesion (TCRA) and 192 cases of transcervical removal of foreign body (TCRF). All operations were performed under B-ultrasonographic or laparoscopic monitoring. Cervical dilator stick was inserted into cervical canal or 200 micro g of misoprostol put in the posterior fornix the evening before operation. The procedures were done according to different indications and purposes. Cases of uterine perforation were divided into two groups: caused by approaching (entry-related) and by surgical instruments (technique-related). RESULTS: Totally sixteen cases (0.45%) of uterine perforation occurred. Seven cases occurred during cervical dilatation and 1 during hysteroscopy inserting lentry-related. Eight cases were technique-related caused by electrode. The incidences of uterine perforation of different operations were: TCRA 4.46% (5/112), TCRF 3.12% (6/192), TCRE 0.27% (4/1 468), TCRM 0.13% (1/797). TCRP and TCRS none. These 16 cases were all diagnosed during operations. 10 cases (62%) by B ultrasound and (or) laparoscopy, 6 cases (38%) by hysteroscopy and clinical features. 13 cases were complete uterine perforations, among them 2 were diagnosed by laparoscopic monitoring, 5 by B-ultrasonic monitoring, 4 by hysteroscopy and 2 by symptoms and B-ultrasound, 3 cases were incomplete uterine perforations in which 2 were diagnosed by laparoscopic monitoring and one by B-ultrasound monitoring. CONCLUSIONS: Half of uterine perforation cases were entry-related, so attention has to be paid to entry of Hegar or hysteroscopy (i.e., not dilate the cervix as possible and introduce the scope under direct vision). The other half were related to surgeons' experience and type of operation. TCRA and TCRF run more risks. B-ultrasound and (or) laparoscopy monitoring during hysteroscopic electro-surgery may help to prevent but not completely avoid uterine perforation.

Adult↗

PubMed2003

[Preliminary clinical application of 99Tcm-HYNIC-TOC imaging in somatostatin receptor-positive tumors].

OBJECTIVE: To evaluate the effect of 99Tcm-HYNIC-TOC imaging in localization of somatostatin receptor-positive tumors. METHODS: Forty-four patients were involved in this study, including 22 neuroendocrine tumors, 10 non-neuroendrocrine tumors and 12 benign diseases. All patients were confirmed by histopathologic diagnosis, and had clinical laboratory data, or 1-2 other imaging procedures. Regional, whole body and SPECT/CT (in positive cases) imagings were acquired at 1 and 4 hours after an intravenous injection of 370 MBq 99Tcm-HYNIC-TOC. 99Tcm-HYNIC-TOC imaging was compared with 111In-petetreotide imaging in 4 cases, and with 131I-MIBG imaging in 10 cases. 99Tcm-HYNIC-TOC imaging was performed before and after treatment in 1 non-Hodgkins lymphoma (NHL) patient. RESULTS: The positive imagings were observed in 19 of 32 cases. The sensitivity, specificity, and accuracy of 99Tcm-HYNIC-TOC imaging for somatostatin receptor-positive tumors are 82.6%, 100%, and 87.5%, respectively. The distribution in vivo of 99Tcm-HYNIC-TOC is similar to that of 111In-petetreotide, and showed high physiological uptake in liver, spleen, and kidneys. 99Tcm-HYNIC-TOC imaging demonstrated intense tumor sites uptake at 1 hour after injection, and revealed the lesions first in 6 patients among the imaging modalities, and more lesions that had not been revealed by 131I-MIBG imaging. Compared with imaging before treatment, 99Tcm-HYNIC-TOC imaging confirmed the tumor regression after treatment in 1NHL. CONCLUSIONS: 99Tcm-HYNIC-TOC is promising for the diagnosis and localization of somatostatin receptor-positive tumors.

Adenoma, Chromophobe↗

PubMed2003

[Study on the anti-oxidation function of nucleic acids].

UNLABELLED: To study the anti-oxidation function of nucleic acids both in animal experiment and in human. (1) Anti-oxidation test in aged rats: Using 32 aged female SD rats, divided into 3 dose groups and 1 control group. Each group had 8 rats. Mixing deferent doses nucleic acid capsule with drinking water and fad doses groups for 50 days. The control group was given only drinking water. On 51st day, measuring the serum malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase(GSH-Px). (2) Eating observation test in aged people: Choosing 120 volunteers aged 50-65 who came from some community in Shanghai, divided into eating observation group and control group. Each group had 60 people. Each people ate 6 capsules per day for 60 days. The control group used same capsule except nucleic acids. On 61st day, measuring the serum MDA, SOD and GSH-Px. RESULTS: Anti-oxidation test in aged rats showed that the concentrations of serum MDA in all dose groups are lower than that of the control (P < 0.01). The concentrations of serum SOD in low and middle dose groups are higher than those of control (P < 0.01, P < 0.05). The concentrations of serum GSH-Px in all dose groups are higher than those of control (P < 0.01). Eating observation test in aged people showed that the concentration of serum SOD in eating observation group is higher than that of the control (P < 0.05), the concentrations of serum MDA and GSH-Px have no significant compared with the control. The appetite, vigorous and energy of eating observation group are significantly improved compared with the control (P < 0.05). CONCLUSION: The nucleic acid capsule has anti-oxidation function in aged female SD rats. The nucleic acids alone could promote SOD and improve the appetite, vigorous and energy of human body.

Aged↗

PubMed2002

Studies of sol-gel ceramic film incorporating methylene blue on glassy carbon: an electrocatalytic system for the simultaneous determination of ascorbic and uric acids.

In this work, we investigated the immobilization of methylene blue in a methyltrimethoxysilane sol-gel ceramic film on a glassy carbon electrode. Up to a certain saturation level, under our conditions, it was found that the methylene blue was tightly held and did not leach out into aqueous solutions, even with continuous immersion for up to 1 month. The electrochemical behavior of the immobilized methylene blue was then studied. pH variation revealed that there were two distinct redox couples whose existences were pH-dependent. The methylene blue/sol-gel film was also examined as an electrocatalytic system for ascorbic and uric acid oxidations. It was revealed that this system was highly sensitive for ascorbic and uric acid sensing (practical determination limits of 5.00 nM and 1.00 nM for ascorbic acid and uric acid, respectively) and also allowed simultaneous determination of these biomolecules. The simultaneous determination of these two analytes in a human urine sample was demonstrated. The stability of the methylene blue/sol-gel film/glassy carbon electrode sensing system was good, with up to at least a month of continual operation.

Ascorbic Acid↗

PubMed2002

Lignin deposition and associated changes in anatomy, enzyme activity, gene expression, and ruminal degradability in stems of tall fescue at different developmental stages.

Stem tissues of tall fescue (Festuca arundinacea Schreb.) were sampled at three elongation stages and three reproductive stages. Anatomical analysis showed the deposition of guaiacyl (G) and syringyl (S) lignin during plant development and the formation of a lignified sclerenchyma ring. A dramatic increase in Klason lignin content was found from elongation stage to reproductive stage. Lignin composition analyzed by gas chromatography-mass spectrometry revealed that S lignin content and S/G ratio increased with stem development, but contents of p-hydroxyphenyl (H) and G lignins decreased during the same period. S lignin content and S/G ratio also increased from the younger upper internode down to the older basal internode of the stem, but G and H lignin decreased in parallel. Relative O-methyltransferase activities increased during stem development and in parallel with the lignification process of stem. The pattern of enzyme activity during development varied with the choice of substrate, with highest activities seen when substrates were caffeoylaldehyde and 5-hydroxyferulic acid, and lowest activities were seen when caffeic acid and 5-hydroxyconiferyl alcohol were used as substrates. The expression of caffeic acid O-methyltransferase and cinnamyl alcohol dehydrogenase genes increased during the stem elongation stage and remained at high levels during the reproductive stages. The changes at anatomical, metabolic, and molecular levels during plant development were closely associated with lignification and degradability. This study provides an integrated picture of the molecular and chemical events that accompany changes in lignin deposition and ruminal degradability.

Alcohol Oxidoreductases↗

PubMed2002

Monolignol biosynthesis in microsomal preparations from lignifying stems of alfalfa (Medicago sativa L.).

Microsomal preparations from lignifying stems of alfalfa (Medicago sativa L.) contained coniferaldehyde 5-hydroxylase activity and immunodetectable caffeic acid 3-O-methyltransferase (COMT), and catalyzed the S-adenosyl L-methionine (SAM) dependent methylation of caffeic acid, caffeyl aldehyde and caffeyl alcohol. When supplied with NADPH and SAM, the microsomes converted caffeyl aldehyde to coniferaldehyde, 5-hydroxyconiferaldehyde, and traces of sinapaldehyde. Coniferaldehyde was a better precursor of sinapaldehyde than was 5-hydroxyconiferaldehyde. The alfalfa microsomes could not metabolize 4-coumaric acid, 4-coumaraldehyde, 4-coumaroyl CoA, or ferulic acid. No metabolism of monolignol precursors was observed in microsomal preparations from transgenic alfalfa down-regulated in COMT expression. In most microsomal preparations, the level of the metabolic conversions was independent of added recombinant COMT. Taken together, the data provide only limited support for the concept of metabolic channeling in the biosynthesis of S monolignols via coniferaldehyde.

Chromatography, High Pressure Liquid↗

PubMed2002

[Assessing the significance of platelet count to in-vitro hemolytic test by roller pump].

This study was directed at estimating the value of platelet count in the course of in-vitro hemolytic tests by roller pump. Five paired in-vitro tests were conducted using the POLYSTAN pump(group A) and COBE pump(group B). The pumps ran 16 hours. The samples for platelet count and plasma-free hemoglobin were taken before pumping, and every 2 hours after 4 hours of pumping. The 2 groups' platelet count and plasma-free hemoglobin levels were found to be linearly increasing with the hours of pumping and linear regression analysis showed the platelet count and plasma-free hemoglobin were positively correlated. These data suggested that platelet count could be used as an index in evaluating the in-vitro hemolytic properties of blood pumps.

Assisted Circulation↗

PubMed2002

Development of selective androgen receptor modulators and their therapeutic applications.

Androgens control a broad range of physiological functions. The androgen receptor (AR), a steroid receptor that mediates the diverse biological actions of androgens, is a ligand inducible transcription factor. Abnormalities in the androgen signaling system result in many disturbances ranging from changes in gender determination and sexual development to psychiatric and emotional disorders. Androgen replacement therapy can improve many clinical conditions including hypogonadism and osteoporosis, but is limited by the lack of efficacious and safe therapeutic agents with easy delivery options. Recent progress in the area of gene regulation by steroid receptors and by selective receptor modulators provides an opportunity to examine if selective androgen receptor modulators (SARMs) could address some of the problems associated with current androgen therapy. Since the composition of the transcriptional initiation complex recruited by liganded AR determines the specificity of gene regulation, synthetic ligands aimed at initiating transcription of tissue and promoter specific genes offers hope for developing better androgen therapy. Establishment of assays that predict synthetic ligand activity is critical for SARM development. Advancement in high throughput compound screening and gene fingerprinting technologies, such as microarrays and proteomics, will facilitate and accelerate identification of effective SARMs.

Androgen Antagonists↗

PubMed2002

[The study of erythrocyte fragility and morphological changes caused by roller pump in vitro].

To observe the erythrocyte fragility and morphological changes of erythrocytes caused by roller pump. Ten tests were divided into two groups, Polystan pediatric pump group A (n = 5) and COBE pump group B (n = 5). Ten whole blood samples (each 400 ml) were circulated in the roller pump for 16 h. Erythrocyte fragility and free hemoglobin were measured before pumping and at every 2 hours during pumping. The possible morphological changes of erythrocytes caused by roller pump were observed by scanning electron microscope. The electron microscopic observation was made before pumping and at every 4 hours throughout pumping. Results showed that the erythrocyte fragility of two groups was not increased during a long period of pumping. The number of acanthocytes of two groups was 1.77/1.81% in the samples before pumping and 6.12/7.13, 9.18/8.73, 13.21/12.89, 16.53/17.21% at 4 h, 8 h, 12 h, and 16 h respectively. The free hemoglobin level of two groups was increased linearly during a long duration of pumping and the index of hemolysis of two groups was 0.296 mg/L/h and 0.3993 mg/L/h respectively. The result shows: 1. the erythrocyte fragility was not increased during a long period of pumping; 2. the erythrocyte membrane was injured or broken by roller pump directly; 3. the morphological changes of erythrocytes would be the basis of post operative hemolysis.

Erythrocyte Deformability↗

PubMed2002

[Observation of the antithrombotic property of a new prosthetic heart valve in sheep].

UNLABELLED: To observe the antithrambotic property of a new prosthetic made double bileaflet valve of all-pyrolytic carbon. METHOD: Fifteen sheeps underwent mitral valve replacement (MVR) with this new mechanical valve. Each animal was placed on cardiopulmonary bypass. All of the sheep were given in an anticoagulation protocol and followed for three months. Final studies were performed on all animals surviving for more than 12 weeks. RESULT: Ten sheeps died within 48 h after operation, five sheeps survived. The long-term survivors were killed forautopsies, two sheeps were killed in the 1st week after operation, one in 12th weeks and two in 2.5 years. Pathological examination of 10 sheeps which died early after operation revealed that there was no either evidence of thromboembotic phenomenon, or any failures of the mechanical valve. Autopsy studies in the five long-term survivors revealed that the sewing ring was covered by a thin layer of microthrombi consisted most of platelets and fibrin in 1th week after operation. The sewing rings was covered by a tissue layer, with partial organized micro thrombi and endothelialization in 12th weeks after the operation. Two and half years after operation, the complete endothelialization presented around the sewing ring without restriction of bileaflet motion. The tissue ingrowth tends to stop at the pyrolytic carbon-fabric interface on both surfaces of left atrium and ventricle. This study demonstrated that the new prosthetic heart valve had not promoted thrombosis and thrombembolism.

Animals↗

PubMed2001

Molecular Cloning and Characterization of Rice Pollen Profilin.

Profilin is a low molecular weight protein and is identified as an actin-binding protein in higher plants. Two pollen-specific cDNA clones of rice, RproA and RproB, were isolated from a cDNA library of rice mature pollen. The two cDNA clones was 821 bp and 805 bp long and contained an open reading frame of 131 amino acids, 5' and 3' untranslated regions and a long poly(A) tail. The comparison of deduced amino acid sequences from RproA and RproB cDNA and other plant profilin cDNA indicated that the two rice profilin are high homologous to each other, showed that 89% similarity to maize (ZmPRO3), 87% to C. dactylon, 83% to H.brasiliensis and 89% to P. pratense. Genomic southernblot analysis suggested the existence of two genes at least. Northern blot and reverse transcriptase polymerase chain reaction analysis demonstrated that the two rice profilin cDNA are anther or pollen specific.

Journal Article↗

PubMed1997

The Effect of Protective Gloves on Manual Dexterity in the Cold Environments.

This article presents a study on the effect of different protective gloves (which are commercially available and commonly used in the cold) on manual dexterity in cold environments. The experiments compared statistically four different types of gloves and two different types of gloving (outer or double) at +19 °C and -10 °C. Performance was determined both objectively and subjectively using two manual dexterity tasks: bolt-nut and pick-up tasks. The response measured was the time of performing each task. Statistical analysis showed that all independent factors such as glove type, participant, object size, and temperature had significant effects on the hand cooling reaction. A significant difference in the performance between the gloves was found in the bolt-nut task. It was also found that outer-inner combination gloving may be an approach to use for precision tasks.

cold climate↗

PubMedDate not supplied

Circadian variation in ischemic threshold in patients with stable angina: relation to plasma endothelin-1.

To investigate circadian variation in ischemic threshold in chronic coronary heart disease (CHD) and its relation to plasma endothelin-1 (ET-1), 21 patients with stable angina underwent treadmill exercise tests twice within a day, performed at 8-9 AM for the first test and at 3-4 PM for the second one. Ischemic threshold was defined as the heart rate at the onset of 1 mm ST segment depression during exercise tests. Blood samples were taken at 5 minutes before each exercise test, and plasma ET-1 was measured for determining the possible relation to ischemic threshold in patients with CHD. The results showed that the heart rate-ischemic threshold in individual patients varied by 10 +/- 1% (range, 2-15%) in the morning and 9 +/- 1% (range, 2-14%) in the afternoon, while there was a mean (11.2%) reduction in the ischemic threshold between 2 time points, with the ischemic threshold being significantly lower in the morning compared with that in the afternoon (115 +/- 22 bpm vs 128 +/- 31 bpm p<0.04). ET-1 values were 6.20 +/- 2.44 ng/L in the morning hours and 4.02 +/- 1.61 ng/L in the afternoon hours, with a statistical significant difference (p<0.01). In conclusion, the present study indicated that circadian variation of plasma levels of ET-1 was likely to be one of the most likely mechanisms involved in reduction in the ischemic threshold in the morning hours.

Adult↗