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Biomedical subjects

S L Li

Publications and source records attributed to S L Li.

At least 19 recordsLinked to original sources
PubMed2001

Chromatographic analysis of Fritillaria isosteroidal alkaloids, the active ingredients of Beimu, the antitussive traditional Chinese medicinal herb.

Bulbus Fritillariae derived from plants of various Fritillaria species is the most commonly used antitussive traditional Chinese medicinal herb and is called Beimu. Herbs derived from similar and/or different species of Fritillaria are also used in Japan and Turkey as traditional or folk medicines. Isosteroidal alkaloids are the main bioactive ingredients in Fritillaria species. As the contents and structure types of these bioactive alkaloids vary in different Fritillaria species, quality control of these active principles in herbal Beimu is very important to ensure its safe and effective clinical use. This review describes the development of chromatographic analyses for the simultaneous qualitative and quantitative determination of the main bioactive Fritillaria isosteroidal alkaloids in herbal and biological samples. The recently developed direct HPLC-evaporative light scattering detection method is the most simple, selective and sensitive assay, and is readily used as a suitable quality control method for the analysis of the active principles of herbal Beimu.

Alkaloids↗
PubMed2001

Low-valent chemistry of cobalt amide. Synthesis and structural characterization of cobalt(II) amido, aryloxide, and thiolate compounds.

The binuclear cobalt(II) amide complex [(CoL2)2-(TMEDA)] (1) [L = N(Si(t)BuMe2)(2-C5H3N-6-Me); TMEDA = Me2NCH2CH2NMe2] has been synthesized by the reaction of anhydrous CoCl2 with 2 equiv of [Li(L)(TMEDA)]. X-ray crystallography revealed that complex 1 consists of two [CoL2] units linked by one TMEDA ligand molecule, which binds in an unusual N,N'-bridging mode. Protolysis of 1 with the bulky phenol Ar(Me)OH (Ar(Me) = 2,6-(t)Bu2-4-MeC6H2) and thiophenol ArSH (Ar = 2,4,6-(t)Bu3C6H2) gives the neutral monomeric cobalt(II) bis(aryloxide) [Co(OAr(Me))2(TMEDA)] (2) and dithiolate [Co(SAr)2(TMEDA)] (3), respectively. Complexes 1-3 have been characterized by mass spectrometry, microanalysis, magnetic moment, and melting-point measurements, in addition to X-ray crystallography.

Aminopyridines↗
PubMed2001

Transcriptional regulation of the p67phox gene: role of AP-1 in concert with myeloid-specific transcription factors.

We have investigated the myeloid-specific transcriptional regulation of p67(phox), an essential component of phagocyte respiratory burst NADPH oxidase. Analysis was carried out on the p67(phox) 5'-flanking region from -3669 to -4 (relative to ATG), including the first exon and intron and part of the second exon. The construct extending from -985 to -4 produced the highest luciferase activity in myeloid HL-60 cells but was not active in HeLa or Jurkat cells, indicating myeloid-specific expression. Four active elements were identified: Sp1/Sp3 at -694, PU.1 at -289, AP-1 at -210, and PU.1/HAF1 at -182, the latter three being in the first intron. These cis elements bound their cognate transacting factors both in vitro and in vivo. Mutation of the Sp1, PU.1, or PU.1/HAF1 site each decreased promoter activity by 35-50%. Mutations in all three sites reduced promoter activity by 90%. However, mutation of the AP-1 site alone nearly abolished promoter activity. The AP-1 site bound Jun and Fos proteins from HL-60 cell nuclear extract. Co-expression with Jun B in AP-1-deficient cells increased promoter activity by 3-fold. These data show that full p67(phox) promoter activity requires cooperation between myeloid-specific and nonmyeloid transcription factors, with AP-1 being the most critical for function.

Base Sequence↗
PubMed2001

Avian haemoglobins and structural basis of high affinity for oxygen: structure of bar-headed goose aquomet haemoglobin.

Haemoglobin from the bar-headed goose (Anser indicus) has higher oxygen affinity than that from its lowland relatives such as greylag goose (A. anser). The crystal structure of bar-headed goose aquomet haemoglobin was determined at 2.3 A resolution and compared with the structures of the goose oxy, human, horse and other avian haemoglobins and the sequences of other avian haemoglobins. Four amino-acid residues differ between greylag goose and bar-headed goose haemoglobins, among which Alaalpha119 and Aspbeta125 in bar-headed goose haemoglobin reduces the contacts between the alpha(1) and beta(1) subunits compared with Pro and Glu, respectively, and therefore may increase the oxygen affinity by loosening the alpha(1)beta(1) interface. Compared with human oxy haemoglobin, the relative orientation of two alphabeta dimers in the bar-headed goose aquomet and oxy Hbs are rotated by about 4 degrees, indicating a unique quaternary structural difference from the typical R state. This new 'R(H)' state is probably correlated with the higher oxygen affinity of bar-headed goose haemoglobin.

Animals↗
PubMed2001

[Evaluation on severity of esophageal varices by color Doppler parameters].

To assess the value of "left gastric vein shunt index" (LGVSI) in the esophageal varices using color Doppler sonography, 32 variceal patients who had large varices(large varices group), 20 patients who had small or medium varices (small or medium varices group), and 15 control subjects were examined with color Doppler sonography. The results showed that the LGVSI in the large varices group was significantly higher than that in the small or medium varices group and in control subjects (P < 0.01). When the best cut-off value of the LGVSI was 0.12, its sensitivity and specificity were 90.6%, 90.0% respectively. Our results suggest that the LGVSI is a useful Doppler ultrasound parameter in evaluating severity of esophageal varices.

Adolescent↗
PubMed2001

Determination of the major isosteroidal alkaloids in bulbs of Fritillaria by high-performance liquid chromatography coupled with evaporative light scattering detection.

A new direct HPLC analytical method using evaporative light scattering detection coupled with a low-temperature adapter for the simultaneous determination of the major biologically active isosteroidal alkaloids in Bulbus Fritillariae, a commonly used antitussive traditional Chinese medicinal (TCM) herb, has been developed. The simultaneous separation of eight Fritillaria alkaloids was achieved on a reversed-phase C8 column with an isocratic mobile phase system consisting of acetonitrile-methanol-water (66.5:3.5:30, v/v) containing 0.006% triethylamine. This method provides good reproducibility and sensitivity for the quantification of six major isosteroidal alkaloids, namely peimissine, verticine, verticinone, imperialine, isoverticine and ebeiedine in different Fritillaria species with overall intra- and inter-day precision and accuracy of less than 11% and higher than 90%, respectively. The assay was successfully utilized to quantify the major biologically active alkaloids in five Fritillaria species. The results demonstrate that this method is simple, selective, and suitable for the quality control of this commonly used antitussive TCM herb, Bulbus Fritillariae. reserved.

Alkaloids↗
PubMed2001

[A study on steam generator in solid amine CO2 purification system].

Objective. To solve the key problems of power matching between process of CO2 steam desorption and process of steam generation, as well as water/vapor separation. Method. Solid amine desorption process was studied by thermodynamic analysis and experiments. The distribution rule of desorption energy was found out and then the power consumption of steam generator was decided. Ceramic insert was designed to separate water and vapor making use of surface tension. Finally, the steam generator was designed on system requirements. Result. Experiments proved that the steam generator can satisfy the demand of the system as well as successfully separate water and vapor, in addition, the selected power is suitable. Conclusion. The design on steam generator was right and practicable.

Air Conditioning↗
PubMed2001

[Determination of imperialine and imperialine-3 beta-D-glucoside in bulbs of Fritillaria pallidiflora by HPLC-ELSD].

AIM: To establish an HPLC (high performance liquid chromatography)-ELSD (evaporative light scattering detector) method for the quantification of chromophore-lacking imperialine (I) and imperialine-3 beta-D-glucoside (II) in bulbs of Fritillaria pallidiflora. METHODS: By optimizing the chromatographic conditions of HPLC and the parameters of ELSD to test the methodology. Column: Kromasil C-18 (5 microns, 200 mm x 4.6 mm), mobile phase: acetonitrile-water-triethylamine (71:29:0.03), flow rate: 1.0 mL.min-1, drift tube temperature: 88 degrees C, gas flow-rate: 2.38 L.min-1. RESULTS: The calibration curves were linear in the range of 60.72-161.92 micrograms.mL-1 for I and 48.72-194.88 micrograms.mL-1 for II. The precisions (RSD) of intra-day and inter-day were less than 1% for I and II. The recoveries of the amounts of 24.28, 30.35 and 36.42 micrograms for I were 97.1%, 96.6% and 96.8%, and 24.20, 30.24 and 36.29 micrograms for II were 95.8%, 96.9% and 96.0%. The minimal detectable concentrations of I and II were 2.43 and 1.53 micrograms.mL-1 respectively. CONCLUSION: The established method is simple, rapid, accurate and sensitive, and can be utilized to determine the contents of imperialine and imperialine-3 beta-D-glucoside in crude drug Yibeimu (derived from the bulbs of Fritillaria pallidiflora).

Cevanes↗
PubMed2001

[The development of the hospital plate washer].

The Developments of the Hospital Plate Washer and its control system are introduced in the paper, and the application of the ultrasound technotology in the plate washer is described too.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

[Investigation of trace elements in hair of patients with prostate carcinoma, benign prostatic hypertrophy, and normal controls].

Five trace metals (Cd, Cu, Fe, Mn, and Zn) in the hair of healthy subjects(n = 10) and patients with benign prostatic hypertrophy (n = 17) and prostatic cancer (n = 18) were determined using atomic absorption spectrophotometry. The results were that zinc level in patients with prostatic carcinoma [(79.1 +/- 37.3) microgram.g-1] was significantly lower than that in patients with benign prostatic hypertrophy [(129 +/- 26.7) microgram.g-1] and normal controls [(152 +/- 31.5) microgram.g-1] (All P < 0.01); Cd, Cu, Fe, and Mn levels in the hair showed no statistic difference among the three groups (P > 0.05). It is suggested that the low zinc level in the hair might provide an important clue for diagnosing prostatic carcinoma at the early stage.

Aged↗
PubMed2000

Single-chain antibodies against human insulin-like growth factor I receptor: expression, purification, and effect on tumor growth.

Insulin-like growth factors (IGF) I and II are potent mitogens for a variety of cancer cells. The proliferative and anti-apoptotic actions of IGF are mediated by the IGF-I receptor (IGF-IR), to which both IGF-I and IGF-II bind with high affinity. To investigate the mitogenic and anti-apoptotic activities of IGF-IR and to achieve better inhibition of IGF-IR function, single-chain antibodies against human IGF-IR (alphaIGF-IR scFvs) were constructed and expressed. IgG cDNA encoding variable regions of light and heavy chains (VL and VH) from mouse IgG were cloned from a hybridoma producing the 1H7 alphaIGF-IR monoclonal antibody [Li et al., Biochem Biophys Res Commun 196: 92-98 (1993)]. The splice-overlap extension polymerase chain reaction was used to assemble a gene encoding the alphaIGF-IR scFv, including the N-terminal signal peptide, VL, linker peptide, VH, and C-terminal DYKD tag. Two types of soluble alphaIGF-IR scFvs, a prototype alphaIGF-IR scFv and its alternative type alphaIGF-IR scFv-Fc, were constructed and expressed in murine myeloma cells. alphaIGF-IR scFv-Fc, containing the human IgG1 Fc domain, was stably expressed in NS0 myeloma cells, using a glutamine synthase selection system, and purified from the conditioned medium of stable clones by protein-A--agarose chromatography. Levels of alphaIGF-IR scFv-Fc expression ranged from 40 mg/l to 100 mg/l conditioned medium. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis analysis under reducing and nonreducing conditions indicated that alphaIGF-IR scFv-Fc is a dimeric antibody. alphaIGF-IR scFv-Fc retained general characteristics of the parental 1H7 monoclonal antibody except that its binding affinity for IGF-IR was estimated to be approximately 10(8) M(-1), which was one-order of magnitude lower than that of 1H7 monoclonal antibody. Injection of alphaIGF-IR scFv-Fc (500 microg/mouse, twice a week) significantly suppressed MCF-7 tumor growth in athymic mice. These results suggest that the alphaIGF-IR scFv-Fc is a first-generation recombinant alphaIGF-IR for the potential development of future alphaIGF-IR therapeutics.

Animals↗
PubMed2000

A VSV-G pseudotyped HIV vector mediates efficient transduction of human pulmonary artery smooth muscle cells.

Attempts were made to infect human vascular smooth muscle cells derived from the pulmonary artery (hPASMC) with two different human immunodeficiency virus (HIV) vector systems. ADA/Luc or HXB2/Luc were generated by cotransfection of luciferase reporter gene vector, pNL4-3-Luc-E- R-, and one of two envelope expressing vectors, pSMADA (R5) or pSMHXB2 (X4). The VSV-G/Luc or VSV-G/GFP were produced by a three-plasmid expression system which consisted of vesicular stomatitis virus G protein (VSV-G) expressing vector, packaging plasmid, and one of two reporter genes (pHR'-CMV-Luc or pHR'-CMV-GFP). We used hPASMC, U87.CD4.CCR5 and U87.CD4.CXCR4 for infection. Neither ADA/Luc nor HXB2/Luc could infect hPASMC, though they could infect U87.CD4 with corresponding coreceptors. On the other hand, the transduction of both VSV-G/Luc and VSV-G/GFP to hPASMC was remarkable. At day 3, the relative proportion of positive cells of hPASMC infected with VSV-G/GFP was 15%. The above finding indicates a direct role of HIV-1 infection in pulmonary hypertension 'a rare complication of HIV-1 infection' and HIV-based vectors could introduce foreign genes into hPASMC for gene therapy of pulmonary hypertension.

Cell Line↗
PubMed2000

[Bone dynamics of repair of mandibular defect with collagen/hydroxyapatite].

OBJECTIVE: To study the effect of collagen/hydroxyapatite(CHA) instead of autogenous bone transplantation on repairing the mandibular defects. METHODS: Ten Chinese experimental minipigs were made 2 cm bone defects in diameter in the mandible. The experimental group was implanted CHA, while the control group was implanted autogenous bone. The basic parameters of bone dynamics were determined by bone metrology. RESULTS: There was remarkable difference between the two groups in the mean distance and mineralization apposition rate of double label bands marked by tetracycline(P < 0.05), while the mean osteoid seam width and mineralization lag time had no remarkable difference(P > 0.05). It suggested that CHA had good osteogenesis. The collagen in CHA offered the condition of bone mineralization, and the mineralization peak of experimental group was present at 4 weeks earlier than that of control group (8 weeks). CONCLUSION: CHA may be a substitute of autogenous bone transplantation in repairing the mandibular defects, and the second operation for offering the implanting bone is avoidable, therefore, CHA may be an ideal material to repair bone defects.

Animals↗
PubMed1999

Critical flanking sequences of PU.1 binding sites in myeloid-specific promoters.

The myeloid-specific transcription factor PU.1 is essential for expression of p47(phox), a component of the superoxide-forming phagocyte NADPH oxidase. The consensus PU.1 binding sequence (GAGGAA) is located on the non-coding strand from position -40 to -45 relative to the transcriptional start site of the p47phox promoter. A promoter construct extending to -46 was sufficient to drive tissue-specific expression of the luciferase reporter gene, but extension of the promoter from -46 to -48 resulted in a significant increase in reporter expression. Mutations of the nucleotides G at -46 and/or T at -47 reduced both reporter expression and PU.1 binding, whereas mutations at -48 had no effect. The PU.1 binding avidity of these sequences correlated closely with their capacity to dictate reporter gene transcription. In parallel studies on the functional PU.1 site in the promoter of CD18, mutations of nucleotides G and T at positions -76 and -77 (corresponding to -46 and -47, respectively, of the p47phox promoter) reduced PU.1 binding and nearly abolished the contribution of this element to promoter activity. We conclude that the immediate flanking nucleotides of the PU.1 consensus motif have significant effects on PU.1 binding avidity and activity and that this region is the dominant cis element regulating p47phox expression.

Base Sequence↗
PubMed1999

Pre-column derivatization and gas chromatographic determination of alkaloids in bulbs of Fritillaria.

A method of precolumn derivatization GC with FID detection was developed for a simultaneous analysis of five major steroidal alkaloids of Fritillaria species, namely ebeiedine, ebeiedinone, verticine, verticinone and imperialine. Derivatization was carried out by trimethylsilylation of the hydroxyl-containing Fritillaria alkaloids to the corresponding trimethylsilylates with trimethylsilylimidazole. Reaction conditions were optimised and the alkaloids derivatives were characterised by on-line GC-MS. The validated GC method demonstrated a good linearity at the sampling ranges used. This analytical method is simple, convenient and reproducible. The developed assay was successfully applied to the determination of the major pharmacologically active alkaloids in three commonly used antitussive Fritillaria species: F. cirrhosa, F. thunbergii and F. pallidiflora.

Alkaloids↗
PubMed1999

[The experimental study of repairing bone defects with allogeneic bone matrix gelatin and plaster].

OBJECTIVE: To study the function of the composite of bone matrix gelatin(BMG) and plaster in the repairing process of bone defects. METHODS: Sixteen New Zealand rabbits which were defected in corpus radii were made as implant zone of bone. Sixteen sides of radii were implanted with the composite of BMG and plaster as experimental group. Others were implanted with BMG(8 sides) and bone stored in alcohol(8 sides) as control groups. The repairing process in bone defects were observed by X-ray and histological examination. RESULTS: There was an obvious osteogenesis in experimental group. The defects of radii were almost healed at 12th week after operation. There were osteogenesis in both control groups, but the repairing process was slower than that of the experimental group. CONCLUSION: The composite of BMG and plaster is a good material for bone transplantation.

Animals↗