Biomedical subjects

Li Chen

Publications and source records attributed to Li Chen.

At least 307 records · Page 17Linked to original sources

PubMed2002

[Superfine comminution technology and its application in the processing of Chinese traditional medicine].

The definition and mechanism of superfine comminution is introduced and the characteristics of equipments in common use for superfine comminution were outlined. The advantages of Chinese traditional medicine processed by superfine comminution are analyzed. The stress was laid on the present state and their advantages and disadvantages of the equipments used in the processing of Chinese traditional medicine. Vibration mill was pointed out to be the optimal equipment for the superfine comminution of Chinese traditional medicine.

Drugs, Chinese Herbal↗

PubMed2002

[Study on the technique of Rehmannia glutinosa virus-free].

The stem tip from germ-free stem segment of Rehmannia glutinosa cultured in test tube can be induced into virus-free seedling. The experiment showed that the proper disinfectant for stem segments of Rehmannia glutinosa was 0.05% HgCl2. The seedings from stem segments grew better with MS in the concentration of agar 0.7% and pH7. The stem tips could be directly induced to seedlings by using MS + 6-BA(0.05 mg/L). The MS media for seedlings virus-free culture are 1/4 macro-elements + 1/2 micro-elements and using edible sugar instead of sucrose, so the cost of media could be decreased to 48.7%.

Culture Techniques↗

PubMed2002

[Non-technical causes of fakes existing in Chinese medicinal material markets].

Non-technical causes of fakes existing in Chinese medicinal materials markets come from three aspects. Source of Chinese medicinal materials is complex and it is difficult to trace back to a source; lawless add impurities and use inferior goods pretending to superior quality and illegally seek for profit; supervising department lack strict blow and deterrent force is limitted.

China↗

PubMed2002

[Isozymes variations among the germplasm resources of Houttuynia in Sichuan].

The peroxidase and esterase isozymes of the germplasm resources of Houttuynia in Sichuan were analyzed. The results showed that it existed plentiful isozymes variations among the germplasm resources of Houttuynia in Sichuan. The cultivated populations had the same isozymes band types as the wild ones. There were 6 different types of peroxidase isozymes bands and 10 different esterase isozymes band totally. Each peroxidase band type was composed of 4 to 6 bands, and esterase isozymes had 5 to 8 bands. There was no significant difference between Houttuynia cordata and Houttuynia emeiensis populations in their isozymes bands types. The results also showed that the number of peroxidase isozymes bands in northern areas was somewhat higher than that in southern areas. However, esterase isozymes band types had no geographic differences.

China↗

PubMed2002

[Study concept of traditional Chinese medicine quality standards].

Chinese medicinal materials quality was controlled mainly by modern analytic approach, secondly by traditional identification method, popularizing based on improvement. Chinese medicine prepared slice quality was controlled mainly by traditional identification method, secondly by modern analytic approach, improving based on popularization.

Chromatography↗

PubMed2002

[Association of PON2 gene polymorphisms in neonates with preterm].

Branch of Institute for Biomedicine,Anhui Medical University,Anqing 246000,China Abstract:The objective is to investigate whether gene polymorphisms in the PON2 gene (PON2148 and PON2311) of neonates are associated with preterm. Using standard questionnaires,194 singleton live born mother-neonate pairs (include preterm cases and term controls) were investigated by the trained field workers with cross-sectional survey at the hospitals in Anqing,Anhui Province,China. Epidemiological and clinical data and blood samples were obtained from 194 mother-neonate pairs. Among neonates,PON2 Ala148Ala homozygote is significantly associated with preterm,compared with Gly148Gly homozygote / Ala148Gly heterozygote before and after adjustment confounders and the same was true for PON2 Ser311Ser homozygote. However,when PON2148 polymorphism and PON2311 polymorphism were considered jointly,no significant gene interaction between PON2148 polymorphism and PON2311 polymorphism in relation to preterm was observed. We draw a conclusion from this research that both PON2148 polymorphism and PON2311 polymorphism in neonates are significantly associated with preterm respectively. But the gene interactions between PON2148 polymorphism and PON2311 polymorphism in neonates are not significantly associated with preterm.

English Abstract↗

PubMed2001

[Study on Relation of Early Immune Reconstitution with Acute Graft-Versus-Host Disease]

To analyze the relation of early immune reconstitution with acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation (all-HSCT), the changes of CD3(+), CD4(+), CD8(+), CD25(+) and CD69(+) cells in peripheral blood from 26 patients with hematologic malignancies were assayed by flow cytometry within 2 months after allo-HSCT. All patients achieved hematopoietic reconstitution, and grade I and II - IV GVHD were developed in 9 and 5 patients, respectively. CD25(+) cells were increased in patients aGVHD at week 2 after transplantation and the peak value was appeared at week 3. The increase of CD25(+) cells was preceded the occurence of clinical signs of aGVHD. The maximal levels of CD25(+) cells increase correlated significantly with the severity of aGVHD. The increase of CD25(+) cells was declined along with remission of aGVHD signs. Our results suggest that analyzing immune reconstitution after allo-HSCT could predict occurence of aGVHD, and CD25(+) cell increase prior occurence of aGVHD is predictive marker for aGVHD.

Journal Article↗

PubMed2000

Surgical treatment of post-traumatic pseudoaneurysms and arteriovenous fistulas.

OBJECTIVE: To report the experience in the diagn osis and treatment of post-traumatic pseudoaneurysms and arteriovenous fistulas. METHODS: A series of 30 patients (11 women and 19 men) with pos ttraumatic pseudoaneurysms were reviewed retrospectively. Among them 7 patients (5 women and 2 men) were associated with arteriovenous fistula. RESULTS: The causes included sharp penetrating trauma (18 cases ), blunt trauma (6 cases) and iatrogenic arterial injury (6 cases). The main cli nical manifestations consisted of local pulsatile mass (26 cases), vascular brui ts (19 cases), thrill (13 cases), ischemia of distal limb (9 cases), neuropathy (5 cases) and pseudoaneurysm rupture (2 cases). All patients underwent surgery. The operations included: ligation of the vessels (12 cases), surgical resection and primary suture repair of the vascular defect or anastomosis (11 cases), vasc ular reconstruction with autogenous saphenous vein (3 cases) and synthetic vascu lar graft (4 cases). CONCLUSIONS: Because of the imminent clinical course, early op eration is usually indicated. The operative treatment is effective and safe for most of the patients with post-traumatic pseudoaneurysms and arteriovenous fist ulas.

Journal Article↗

PubMed2000

Mitochondrial tRNA(Trp)s Imply a Eubacterial Origin.

Three mitochondrial tRNA(Trp)s genes from Oryza sativa, Homo sapiens and Saccharomyces serevisea were constructed. In vitro transcripts of these mitochondrial tRNA(Trp)s genes were able to be tryptophanylated by Bacillus subtilis tryptophanyl-tRNA synthetase (TrpRS), but could not be catalyzed by TrpRS from rat liver. Kinetic assay showed that B. subtilis TrpRS had half the binding capacity for mitochondrial tRNA(Trp)s than for wild type tRNA(Trp). While in the catalytic efficiency, the k(cat)/K(m) value of mitochondrial tRNA(Trp)s from O.sativa and S.serevisea by B.subtilis enzyme was reduced by 400-fold and 1 200-fold respectively as that of B.subtilis tRNA(Trp). Experimental results suggested that mitochondrial tRNA(Trp)s implied a eubacterial origin.

Journal Article↗

PubMed2000

Immobilized Tryptophanyl-tRNA Synthetase from Bacillus subtilis.

In order to investigate the recognition mechanism and the relationship between structure and function of tRNA(Trp) with tryptophanyl-tRNA synthetase (TrpRS), TrpRS from Bacillus subtilis was purified and immobilized on CNBr-activated Sepharose 4B. Protein recovery and activity recovery of the immobilization were 95.5% and 31.3%, respectively. Properties of immobilized TrpRS were studied in detail. The thermal stability and the shelf stability of immobilized TrpRS were much higher than those of the native TrpRS. Besides these, the immobilized TrpRS, with good operation stability, had increased optimum temperature and optimum pH. A 56-base single-stranded RNA library containing 20 consecutive completely randomized bases was subjected to 3 successive rounds of immobilized TrpRS column selection with SELEX method, resulting in a sharp increase of the percentage of the RNA pool that could bind immobilized TrpRS from 4.3% for the first round pool to 14.7% for the third-round pool. After sequencing the third-round RNA pool, a RNA secondary structure resembling the structure of the acceptor stem in tRNA(Trp) was obtained though the selection. All the results indicated that immobilized TrpRS could be used as an affinity chromatography matrix and was qualified for the SELEX of a RNA pool simulating tRNA(Trp) molecule.

Journal Article↗

PubMed1999

A Discriminator Base in tDNA(Trp).

The discriminator base G73 was one of the major identity elements of tRNA(Trp). Aminoacylation assay and CD spectrum of tDNA(Trp)-NCCrA demonstrated that under the same pH, the change of discriminator base affected tRNA conformation at the 3' terminus while tDNA(Trp) with the same discriminator base exhibited different conformation and aminoacylation activity under various pH conditions. Our results showed that it was the conformation of tRNA, but not the base itself, that determined the accurate recognition between tRNA and its cognate synthetase.

Journal Article↗

PubMed1999

Analysis of Phylogenetic Relationships Among Twelve Yeast Species.

Partial sequences of 25 S ribosomal DNA for nine Candida yeast and one Kluyveromyces yeast strains were cloned and determined. We compared them with two published 25 S rDNA sequences of Saccharomyces cerevisiae and Candida albicans. An evolutionary tree of the twelve species was inferred from about 370 sites of 5' end of 25 S ribosomal DNA using the methods of neighbor-joining and bootstrap. The molecular data indicate a very close affinity between Candida kefyr CBS834 and Kluyveromyces cicerisporus CBS4857.

Journal Article↗

PubMed1999

Differential and Tissue-specific Expression of Mitochondrial Elongation Factor Tu and Ts during Development.

The mitochondrial elongation factors Tu and Ts (EF-Tu(mt) and EF-Ts(mt)) are nuclear gene-encoded mitochondrial proteins and play important roles in growth and development. We prepared antibodies against EF-Tu(mt) and EF-Ts(mt) using purified recombinant EF-Tu(mt) and EF-Ts(mt). Western analysis indicates EF-Tu(mt) and EF-Ts(mt) are expressed differently in various tissues. Their expression in heart and liver increased during development and reached plateau at maturation. Expression of EF-Tu(mt) and EF-Ts(mt) exhi-bited similar tissue-specificity and changed synchronically during development. These results suggest that expression levels of EF-Tu(mt) and EF-Ts(mt) may be regulated by a similar mechanism related to the metabolic state of the cells.

Journal Article↗

PubMed1998

Synthesis, Characterization, and Molecular Structures of Diethylnitrosamine Metalloporphyrin Complexes of Iron, Ruthenium, and Osmium.

Diethylnitrosamine reacts with [(TPP)Fe(THF)(2)]ClO(4) (TPP = 5,10,15,20-tetraphenylporphyrinato dianion) in toluene to generate the bis-nitrosamine complex, [(TPP)Fe(Et(2)NNO)(2)]ClO(4), in 96% isolated yield. The related [(TTP)Fe(Et(2)NNO)(2)]SbF(6) (TTP = 5,10,15,20-tetra-p-tolylporphyrinato dianion) complex is prepared in 70% isolated yield via a similar reaction in CH(2)Cl(2). Reaction of [(TPP)Fe(Et(2)NNO)(2)]ClO(4) in CH(2)Cl(2) with NO gas results in the displacement of one of the Et(2)NNO ligands to give the air-sensitive and thermally sensitive [(TPP)Fe(NO)(Et(2)NNO)]ClO(4) derivative. Reaction of (OEP)Ru(CO) (OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion) with NOBF(4) in CH(2)Cl(2) gives [(OEP)Ru(NO)(H(2)O)]BF(4) as the final isolated product (after exposure to air) in 71% isolated yield. The aqua ligand is then displaced by Et(2)NNO in CH(2)Cl(2) to give [(OEP)Ru(NO)(Et(2)NNO)]BF(4) in 82% isolated yield. The valence isoelectronic (OEP)Ru(CO)(Et(2)NNO) compound is prepared in 71% isolated yield by the addition of excess Et(2)NNO to (OEP)Ru(CO) in CH(2)Cl(2). The nitrosyl amine complex [(OEP)Ru(NO)(HNEt(2))]BF(4) is prepared (i) in 78% yield by diethylamine addition to [(OEP)Ru(NO)(H(2)O)]BF(4) or (ii) in 71% isolated yield by diethylamine addition to [(OEP)Ru(NO)(Et(2)NNO)]BF(4). The osmium nitrosamine complexes, (TTP)Os(CO)(Et(2)NNO) and (OEP)Os(CO)(Et(2)NNO), are prepared in 74% and 66% yields, respectively, by diethylnitrosamine addition to the precursor (porphyrin)Os(CO) compounds in CH(2)Cl(2). The nitrosyl [(OEP)Os(NO)(Et(2)NNO)]BF(4) derivative is prepared in quantitative yield (by IR and (1)H NMR spectroscopy) by the reaction of (OEP)Os(CO)(Et(2)NNO) with NOBF(4). Labeling studies using (15)NOBF(4), Et(2)N(15)NO, and Et(2)NN(18)O have been used to assign the nitrosyl and nitrosamine bands in the IR spectra of several of the complexes. The solid-state structures of [(TPP)Fe(THF)(2)]ClO(4), [(TPP)Fe(Et(2)NNO)(2)]ClO(4), [(OEP)Ru(NO)(H(2)O)]BF(4), (OEP)Ru(CO)(Et(2)NNO), and (TTP)Os(CO)(Et(2)NNO) have also been determined by single-crystal X-ray diffraction. The Et(2)NNO ligands display a rare eta(1)-O binding mode in all three nitrosamine complexes.

Journal Article↗

PubMed1998

Synthesis, Characterization, and Solid-State Molecular Structures of Nitrosoarene Complexes of Osmium Porphyrins.

The reactions of (por)Os(CO) (por = TPP, TTP, OEP, TMP) with nitrosoarenes (ArNO; Ar = Ph, o-tol) in refluxing toluene generate the (por)Os(ArNO)(2) complexes in 45-76% yields (TTP = 5,10,15,20-tetra-p-tolylporphyrinato dianion, TPP = 5,10,15,20-tetraphenylporphyrinato dianion, OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion, TMP = 5,10,15,20-tetramesitylporphyrinato dianion). The nu(NO) of the coordinated PhNO groups in the (por)Os(PhNO)(2) complexes occur in the 1295-1276 cm(-)(1) range, and decrease slightly in the order TPP (1295 cm(-)(1)) > TTP (1291 cm(-)(1)) > OEP (1286 cm(-)(1)) > TMP (1276 cm(-)(1)). The reaction of (TTP)Os(CO) with 1 equiv of PhNO in CH(2)Cl(2) at room temperature generates a 1:3 mixture of (TTP)Os(CO)(PhNO) and (TTP)Os(PhNO)(2) in ca. 40% isolated yield. The nu(CO) of (TTP)Os(CO)(PhNO) is at 1972 cm(-)(1) (KBr), which is 56 cm(-)(1) higher in energy than that of the precursor (TTP)Os(CO). When this mixture and excess PhNO are dissolved in toluene and the solution is heated to reflux, quantitative conversion to the (TTP)Os(PhNO)(2) product occurs. IR monitoring of the reactions of (por)Os(CO) with 1 equiv of PhNO in CH(2)Cl(2) reveal similar formations of the respective (por)Os(CO)(PhNO) intermediates for the TTP (1968 cm(-)(1); Deltanu(CO) = +74 cm(-)(1)), TMP (1966 cm(-)(1); Deltanu(CO) = +63 cm(-)(1)), and OEP (1958 cm(-)(1); Deltanu(CO) = +72 cm(-)(1)) analogues. Five of these (por)Os(ArNO)-containing complexes have been fully characterized by spectroscopic methods and by single-crystal X-ray crystallography. All the nitrosoarene ligands in these complexes are attached to the formally Os(II) centers via an eta(1)-N binding mode.

Journal Article↗

PubMed1998

Nitrosylation of Octaethylporphyrin Osmium Complexes with Alkyl Nitrites and Thionitrites: Molecular Structures of Three Osmium Porphyrin Derivatives.

(OEP)Os(CO) reacts with n-butyl nitrite to give, after workup, the (OEP)Os(NO)(O-n-Bu) trans addition product (OEP = octaethylporphyrinato dianion). Similarly, the reaction of (OEP)Os(CO) or [(OEP)Os](2) with isoamyl nitrite gives the corresponding nitrosyl alkoxide, (OEP)Os(NO)(O-i-C(5)H(11)). The related reactions of (OEP)Os(CO) or [(OEP)Os](2) with isoamyl thionitrite gives the (OEP)Os(NO)(S-i-C(5)H(11)) nitrosyl thiolate. The reaction of the [(OEP)Os](2)(PF(6))(2) reagent with isoamyl thionitrite gives the nitrosylation product, [(OEP)Os(NO)]PF(6), which undergoes anion hydrolysis to give the isolable difluorophosphate (OEP)Os(NO)(O(2)PF(2)) derivative. Interestingly, the reaction of O(2)NC(6)H(4)N=NSPh with [(OEP)Os](2) gives the (OEP)Os(SPh)(2) product with loss of the arylazo fragments. The solid-state structures of (OEP)Os(NO)(O-n-Bu), (OEP)Os(NO)(O(2)PF(2)), and (OEP)Os(SPh)(2) have been determined by X-ray crystallography.

Journal Article↗

PubMedDate not supplied

Depressive symptoms and risk factors in Chinese persons with type 2 diabetes.

BACKGROUND: Our objective was to study depressive symptoms and potential risk factors in Chinese persons with type 2 diabetes. METHODS: Zung self-rating depression scale (ZSDS) was used to scan depressive symptoms. Correlation between depressive symptoms and sociodemographic and medical factors were analyzed by logistic regression. RESULTS: Of 222 patients with type 2 diabetes (115 males, 107 females, age 56.36 +/- 12.67 years, disease duration 7.36 +/- 6.32 years), a total of 51 (23.0%) patients were categorized as having depressive symptoms. Percentage of depressive symptoms in females was higher than in males (29.0% vs. 17.6%, chi(2)=4.2, p <0.05). Percentage of depressive symptoms increased with increase of diabetes duration, HbA(1c), TC, TG, and number of chronic diabetic complications. Univariate logistic regression showed that diabetes duration, number of chronic diabetic complications, HbA(1c), female gender, and TC were significantly correlated with depressive symptoms (p <0.05). Multivariate logistic regression analysis indicated that variables, i.e., diabetes duration, number of chronic diabetic complications, HbA(1C), and female gender were significantly and independently associated with depressive symptoms (p <0.05). CONCLUSIONS: In this Chinese population, depressive symptoms in subjects with type 2 diabetes were frequent. Diabetes duration, number of chronic diabetic complications, HbA(1C), and female gender were independent risk factors for depressive symptoms. Further research on the relationship between diabetes and depressive symptoms in China was necessary.

Adult↗

PubMedDate not supplied

Hydroxyapatite surface modified by L-lactic acid and its subsequent grafting polymerization of L-lactide.

A new method of surface modification of hydroxyapatite nanoparticles (n-HA) by surface grafting reaction of l-lactic acid and ring-opening polymerization of l-lactide (LLA) was developed. Two modified HA nanoparticles were obtained: HA modified by l-lactic acid (l-HA) and HA grafting with poly(l-lactide) (PLLA; p-HA). The modified surface of n-HA was attested by Fourier transformation infrared, (31)P MAS NMR, and thermal gravimetric analysis. The results showed that l-lactic acid could be easily grafted onto the n-HA surface by forming a Ca carboxylate bond and initiated by the hydroxyl group of the grafted l-lactic acid and LLA could be graft-polymerized onto the n-HA surface in the presence of stannous octanoate. The highest grafting amounts of l-lactic acid and PLLA were about 33 and 22 wt %, respectively. The modified HA/PLLA composites showed good mechanical properties and uniform microstructure. The tensile strength and modulus of the p-HA/PLLA composite containing 15 wt % of p-HA were 67 MPa and 2.1 GPa, respectively, while those of the n-HA/PLLA composites were 45 MPa and 1.7 GPa, respectively. The elongation at the break of the l-HA/PLLA composite containing 15 wt % l-HA could reach 44%, in comparison with 6.5% of the n-HA/PLLA composites containing 15 wt % n-HA.

Durapatite↗