Biomedical subjects

H Li

Publications and source records attributed to H Li.

At least 973 records · Page 54Linked to original sources

PubMed1999

[The effect of mobile phase on the enantiomeric separation of cyfluthrin by chiral high performance liquid chromatography].

The enantiomeric separation of cyfluthrin on chiral stationary phase(CSP), derived from (R)-N-(3,5-dinitrobenzoyl) phenylglycine (Prikle type 1-A CSP) has been studied by using different hexane-alcohol mixtures as mobile phase. Mobile phase strength and composition have shown an important role in the chromatographic separation of eight isomers of cyfluthrin. Increase of the mobile phase strength reduces the retention of the eight isomers, while the diastereomeric selectivity is decreased and the enantiomeric selectivity remains almost unchanged. Also, the resolution varies in accordance with the steric hindrance of the alcohol. Secondary or tertiary alcohols impart a greater resultion to the CSP than primary alcohols. Peak shapes are better with the lower alcohols than the higher alcohols. For the enantiomeric separation of cyfluthrin on Pirkle type 1-A CSP, hexane-tert-butanol and hexane-2-propanol are better binary mobile phases.

Chromatography, High Pressure Liquid↗

PubMed1999

[Chiral drug separation by supercritical fluid chromatography].

Because of the high-efficiency, fast separation, low-temperature analysis and applicable to a wide variety of detectors, supercritical fluid chromatography(SFC) is an attractive alternative for chiral drug separation. The development and application of this technique in enantiomer separation are reviewed with 48 references. The separation modes and the choices of experimental condition are discussed.

Adrenergic beta-Antagonists↗

PubMed1999

[Application of high performance liquid chromatography to the study on the production of maltooligosaccharide by synergistic action of two-enzymes].

This paper describes the application of high performance liquid chromatograpy to the study on the production of maltooligosaccharide by synergistic action of two-enzymes. Seven sugars in products were separated on a column of Nucleosil C18 with water as the mobile phase and determined refractometrically. Meanwhile, for the preparation of maltooligosaccharide, the effect of supplementing rate of the two enzymes on the content of maltooligosaccharide in products is examined in this paper. The optimun technological conditions were obtained by using the orthogonal design and the amount of the two enzymes added was determined. Thus more than 70% of M3-M6 maltooligosaccharide in product was obtained.

Chromatography, High Pressure Liquid↗

PubMed1999

[Gas chromatography/mass spectrometry analysis for determination of methyl alpha-(6-methoxyl-2-naphthyl) propionate from carbonylation].

alpha-(6-Methoxyl-2-naphthyl) ethanol can be carbonylated to form methyl-alpha-(6-methoxyl-2-naphthyl)propionate catalyzed by a catalyst in the pressnce of methanol. High efficiency capillary gas chromatography and GC/MS technique were used for determining products which were obtained from the carbonylation. An OV-101 fused silica capillary column (25 m x 0.2 mm i.d.) and a flame ionization detector (FID) were employed in the GC analysis. The column temperature was kept at 250 degrees C. Mass spectra were obtained by electron impact at 70 eV. The structures of four compounds were identified. The major product is methyl-alpha-(6-methoxy-2-naphthyl) propionate, and the two by-products are 2-vinyl-6-methoxynaphthalene and 1-methoxy-(6'-methoxy-2'-naphthyl)ethanol.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1999

[The prospects of research on VR rehabilitation engineering].

In this paper, we present the recent development of Vitual Reality (VR) technology and rehabilitation engineering and discuss the rationality and feasibility of the application of VR to rehabilitation. With VR technology, psychological induction can be better introduced in rehabilitating exercises and patients can be tremendously released from fret during traditional physical training for rehabilitation. The VR is expected to bring about a technological revolution in rehabilitation engineering.

Computer Simulation↗

PubMed1999

[Separation of enantiomeric labetalol by reversed-phase high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic method for the separation of labetalol enantiomers was developed. In the method, 2, 3, 4, 6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC) was chosen as the reagent for pre-column chiral derivatization of labetalol to give four diastereomeric thiourea derivatives. These derivatives were efficiently separated on a Nova-Pak C18 column using V(MeOH):V(0.01 mol.L-1(pH 7.00) H2PO4(-)-HPO(4)2- buffer) = 51:49 as the mobile phase and detected by UV detector at a wavelength of 250 nm or fluorescence detector at lambda ex = 340 nm and lambda em = 440 nm. The effects of the pH of mobile phase on the retention and fluorescence absorbance are also discussed.

Adrenergic alpha-Antagonists↗

PubMed1999

[Determination of enantiomeric purity for epinephrine by high performance liquid chromatography].

A procedure for the resolution of D,L-epinephrine and the determination of D-isomer ratio in a pharmaceutical formulation is described. The optical isomers of epinephrine were resolved by RP-HPLC with heptakis(2,6-di-O-methyl-beta-cyclodextrin) as a chiral mobile phase additives. The results showed that a correction factor must be introduced into the equation used for the calculation of the percentage of D-epinephrine, because the UV absorbance may not be the same when DM-beta-CD is present. Quantitation was achieved with external and internal standard method, HVA as an internal standard. This method can be used for the determination of the D-isomer in the L-epinephrine pharmaceutical formulation. The results showed that the mass fraction of D-isomer in the formulation increased during the period of storage.

Chromatography, High Pressure Liquid↗

PubMed1999

[Molecular clone and sequence analysis of cDNA fragments of hog cholera virus strain C].

The 5' nonencoding region, p23 and p14 encoding region and E1 gene of hog cholera virus (HCV) strain C were amplified from total RNA extracted from HCV strain C infected rabbit spleen by reverse transcription and nested or half--nested PCR. The PCR products were cloned into pGEM-T vector. Nucleotide sequencing was performed using an ABI PRISM sequencing device; based on the incorporation of fluoresect labelled dideoxynuclotide teminators. The obtained sequences on 5' noncoding region and part of p23 and p14 encoding region were compared with HCV strains Shimen and C sequenced in Moormann's lab. The result showed that the homology between HCV strains C sequenced in this report and in Moormann's lab was 99.19%, and the homology between HCV strains Shimen, the standard virulent HCV strain in China, and C sequenced in this report was 94.69%. It was also discovered that the base C at 244 of the genome of HCV strains Shimen and C sequenced in this report was absent at the genome of C strain sequenced in Moormann's lab et al.

5' Untranslated Regions↗

PubMed1999

[Amplification of phytoplasma 16S rDNA from banana bunchy top disease, RFLP and sequence analysis of 16S rDNA fragment].

Extract DNA from banana plants with banana bunchy top disease and amplify the phytoplasma 16S rDNA fragment by nested PCR. The classification of the phytoplasma established on the basis of 16S rDNA restriction patterns was examined by performing a sequence analysis of 16S rDNA fragment. The RFLP pattern, sequence data and phylogenic tree showed that this phytoplasma should belong to Group I(Phytoplasma asteri).

Base Sequence↗

PubMed1999

[The effect of N+ implantation on SOD activity of Deinococcus radiodurans and induction of Mn-SOD].

The induction of Mn-SOD and effect of N+ of 20 keV implantation on SOD activity of D. radiodurans were investigated. The results were as follows: (1) SOD activity of D. radiodurans had a little change when implantation dose was less than 8 x 10(14) N+/cm2, and increased gradually from 8 x 10(14) to 60 x 10(14) N+/cm2, and then decreased rapidly; (2) the test of adding H2O2 and CHCl3-CH3CH2OH which could inhibit different types of SOD showed that most SOD activity of D. radiodurans was constituted by Fe-SOD in general physiology and less then 8 x 10(14)N+/cm2 dose, and higher implantation dose induced increase of Mn-SOD activity.

Deinococcus↗

PubMed1999

[SDS-PAGE and EITB analysis of the protein components of different isolates of Schistosoma japonicum in China and Japan].

AIM: To make a supplementary observation on the protein components prepared from adult S. japonicum of 4 different isolates from Zhejiang, Jiangxi, Taiwan Provinces of China and Japan in origin and to observe antigen reactivity of the above-mentioned isolates together with adult worms from Anhwi, Hubei, Sichuan and Yunnan isolates against heterologous anti-Oncomelania h. hupensis (collected from Guangxi, China and Japan) sera by EITB. METHODS: SDS-PAGE and EITB. RESULTS AND CONCLUSION: SDS-PAGE showed that by Coomassie blue staining, male S. japonicum from Jiangxi, Zhejiang, Taiwan Provinces and Japan isolales revealed 7-17 bands while female worms revealed 1-6 bands. The protein patterns of Taiwan and Zhejiang male worm were similar, but slight difference could be seen above 81 kDa. By silver staining, male worms of the 4 isolates revealed 10-23 bands while female worms revealed 1-19 bands. Male worms from Japan not only showed less bands but also differed in their pattern as compared to those of other Chinese isolates. Results of EITB revealed that each of the 4 isolates had slightly different pattern but all of the tested isolates had common antigens with their heterologous snail hosts i.e., Oncomelania h. hupensis from Guangxi, China and Japan.

Animals↗

PubMed1999

[Expression of Schistosoma japonicun fatty acid binding protein gene in silkworm cells and larvae].

AIM: To express the fatty acid binding protein (Sj14FABP) gene of Schistosoma japonicun in the silkworm cells and larvae. METHODS: A 600 bp DNA fragment containing Sj14FABP gene was cloned into baculovirus transfer vector of pBacPAK His1 to construct recombinant transfer vector Sj14-pBac PAK His1. Coinfection was accomplished with this vector and Bombyx mori nuclear polyhedrosis virus (BmNPV) DNA in BmN cells. The recombinant virus of Bm-Sj14 was screened using dot-blotting. The BmN cells and silkworm larvae were infected with Bm-Sj14 to express Sj14FABF gene. Western blotting and ELISA were used to identify the antigenicity of the recombinant protein. RESULTS: Sj14FABP gene was successfully expressed in the BmN cells and silkworm larvae infected with Bm-Sj14. The product was a 18 kDa fusion protein. The yield in BmN cells was about 100 micrograms/1 x 10(6) cells and 33 micrograms/ml cell supernatant. In silkworm larvae, the product yield was 4 mg/ml haemolymph as well as 4.6 mg/g silkworm tissue. The recombinant protein could be recognized by Western blotting and ELISA using the sera from mice immunized with SWAP. CONCLUSION: Sj14FABP gene has been successfully expressed in BmNPV system and the product has high antigenicity.

Animals↗

PubMed1999

[A pilot study on malaria control by using a new strategy of combining strengthening infection source treatment and health education in mountainous areas of Hainan province].

AIM: To explore a new malaria control strategy that fits current epiodemiological condition and coincides with modern medicine model and the principle of cost-benefit. METHODS: The new strategy highlights the risk villages and risk population as the focal point and integrates health education with behavioral intervention. The main anti-malaria measures consists of carrying out health education in risk villages, giving mass drug administrations in risk population staying overnight in the mountain, following up malaria cases for implementing radical cure, but without using traditional residual spraying or impregnating bednets with insecticides. RESULTS: After having adopted the new strategy and taken the control measures, the people's knowledge about malaria increased to a higher level and the indices of malaria reduced to a lower level. The rate of bednet-using in the population was increased from 26.8% to 72.6%. The annual parasite incidence (API) of malaria was declined from 3.5% in 1994 to 1.1% in 1996 and 0.8% in 1997, and the API of falciparum malaria was declined from 1.0% to 0.3% and 0.3% respectively in the townships at the same time. The parasite rate(PR) of malaria was declined from 7.2% in May, 1995 to 2.1% in November, 1996 and 1.2% in October, 1997 and the PR of falciparum malaria was declined from 1.2% in May, 1995 to 0.1% in October, 1997. The proportion of villages without malaria cases was increased from 18.6% in 1994 to 54.2% in 1997, and the number of risk villages with a malaria incidence above 5% was reduced from 14 to 2 at the same time. The ratio of cost/benefit was 1:2.4 in 1995-1996 and 1:4.4 in 1997, showing a better economic benefit. CONCLUSION: The expectant result has been obtained, thereby providing new experience for the malaria control in the mountainous areas of Hainan Province.

China↗

PubMed1999

[Quantitative analysis of vocal fold vibration].

OBJECTIVE: To measure vocal fold vibration quantitatively and study the effects of gender and phonation mode. METHOD: The authors adopted a new computerized image analysis technique and EGG in 60 normal speakers, and the parameters of vocal fold vibration were measured and analyzed according to the loudness, pitch and gender. RESULT: With frequency increasing, CQ got smaller and OQ larger which expressed longer open phase. As intensity increased, the duration of open phase became shorter and the closing phase got relatively much shorter. Males had a longer closed phase than females. The closing duration appeared relatively shorter than opening duration in phonation. CONCLUSION: The quantitative measures of vocal fold vibration become feasible with modern computers and commercially available image analysis software. Certain features of vocal fold vibration vary with intensity variations, while others vary with gender or frequency variation.

Adolescent↗

PubMed1999

[The influence of short-term pure tone exposure on amplitude of distortion-product otoacoustic emissions and spectral history].

OBJECTIVE: To observe the changs of the amplitude and the spectral history of DPOAE in the slightly damaged cochlea. METHOD: Fifteen of young person with normal hearing were exposed to 4 kHz short-term pure tone (Level = 130 dB SPL) for 3 minutes to analysis the change of DPOAE in details after Temporary Threshold Shift (TTS). RESULT: The comparison of pre- and postexposure showed that the thresholds of sound reflex is 9.78 +/- 6.98, 8.04 +/- 5.58, 13.0 +/- 5.58 dB HL and 8.82 +/- 6.23, 5.75 +/- 4.42, 9.05 +/- 2.27 dB HL in 0.5, 1, 2 kHz, respectively. The amplitude of DPOAE decreased 4.28 dB SPL in 6 kHz, and the spectral history rippled significantly. The coefficience of variance is 5.18 +/- 1.63%. The combination of the amplitude and the coefficience of variance indicated that 80.0% of those is abnormal. CONCLUSION: The results confirmed that the spectral history of DPOAE is a sensible tool to assess the slightly cochlear lesion together with the amplitude of DPOAE.

Adolescent↗

PubMed1999

[Study on c-myc mRNA and its product expression during hair cell regeneration in the chick basilar papilla].

OBJECTIVE: To study the effect of c-myc gene expression during hair cell (HC) regeneration in the chick basilar papilla (BP) following getamicin ototoxicity. METHOD: c-myc mRNA and its product (c-myc protein) expression in the damaged region was histologicolly analyzed by in situ hybridization and immunohistochemistry. Thirty-six animals received one subcutaneous injection of gentamicin sulfate (50 mg/kg) daily for ten days. The animals were allowed to survive 1, 3, 7, 14, 21 or 28 days (n = 6 in each group) before sacrifice and preparation for both in situ hybridization and immunohistochemistry. Twelve animals were sacrificed as control for each groups (n = 2). RESULT: The results showed that the supporting cells and cells in the lumenal nuclear layer within the damaged region were strongly labeled for c-myc transcripts and its protein. Seven days after last injection, the highest level of c-myc mRNA and c-myc protein expression was observed in the injured sensory epithelium. C-myc gene expression began to decline from fourteen days post injection. High level expression of c-myc gene was discussed in relation to the time and location of HC regeneration. CONCLUSION: The results indicate that c-myc gene expression may be an important molecular event in HC regeneration and may play a role in regulating progenitor cells proliferation.

Animals↗

PubMed1999

[Treatment for chronic dacryocystitis by probing through naso-lacrimal duct under endoscopy].

OBJECTIVE: To determine the possibility of curing chronic dacryocystitis by probing through naso-lacrimal duct under endoscopy. METHOD: 30 adult eyes with chronic dacryocystitis were divided into two groups: 20 treated under endoscopy as endoscopy group and 10 under rhinoscope as control. RESULT: In endoscopy group, treatment in all 20 eyes successed at the first time, but in control group only in 8 of the 10 eyes successed at the first time and the other 2 needed second surgery. CONCLUSION: Treatment for chronic dacryocystitis by probing through naso-lacrimal duct under endoscopy is better.

Chronic Disease↗

PubMed1999

[The applied anatomy and measure of nasolacrimal duct].

OBJECTIVE: To know the anatomy of nasolacrimal duct. METHOD: 80 half-skulls of chinese adult were used to observe shapes of the orifice. RESULT: Five shapes of the orifice were found. Slit-shape was the most in all shapes. 73 nasolacrimal ducts and situation of orifices have been measured with results as follows: (1) The nasolacrimal duct length is 14.14 mm (mean value); (2) The distance from the inferior margin of the anterior nostril to the anterior margin of the orifice (D.N.O.) is 29.00 mm (mean value); (3) The distance from the anterior attachment of the inferior turbinate to the anterior margin of the orifice is 11.70 mm (mean value); (4) The distance from the inferior margin of the anterior nostril to the anterior attachment of the inferior turbinate (D.N.T) is 18.30 mm (mean value). With analysis of linear regression, the relationship between the "D.N.T." and the nasolacrimal duct length, the "D.N.T." and the "D.N.O." is positive linear correlation respectively, "D.N.T." has been able to be measured easily, so the nasolacrimal duct length and the situation of the orifice have been recognized. CONCLUSION: D.N.T. may be used in clinical teaching and researching work.

Adult↗