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Biomedical subjects

Ge Lin

Publications and source records attributed to Ge Lin.

33 records · Page 2Linked to original sources

Newly expressed proteins of mouse embryonic fibroblasts irradiated to be inactive.

It has been found that post-radiation mouse embryonic fibroblasts can well maintain the pluripotency in human embryonic stem cells. However, the molecular mechanism remains unclear. In the present study, the new protein expression profile of post-radiation mouse embryonic fibroblasts was analyzed by immobilized pH gradient 2-dimensional polyacrylamide gel electrophoresis. Image analysis following silver staining revealed (969+/-57) vs. (1085+/-107) spots from post-radiation mouse embryonic fibroblasts and pre-radiation ones, respectively. Some newly expressed proteins, which were only abundantly present after irradiation, were subjected to peptide mass fingerprint analysis and identified using MALDI-TOF-MS, SWISS-PROT database, and RT-PCR. Several of those proteins were preliminarily identified to participate in cytokine secretion, cell signal transduction, transcriptional regulation, and apoptosis, etc., which suggested that inactive post-radiation mouse embryonic fibroblasts expressed some new proteins that may underlie the molecular mechanisms to maintain the pluripotency in human embryonic stem cells.

ADAM Proteins↗

A method for testing low-value spatial clustering for rare diseases.

This paper proposes a method that tests for the existence of low-value spatial clustering while accounting for the influence of high-value clustering. Although the method was developed in reference to the Tango test, it can be extended to other testing methods. The simulation results showed that the proposed method is able to effectively detect low-value clustering with substantially lower rates of type I errors than those of the Tango test, while maintaining comparable statistical power. Applying the method in a case study of leukemia in Minnesota demonstrated an overall tendency toward low-value clustering of leukemia mortality for males but provided inconclusive results for females.

Confounding Factors, Epidemiologic↗

Metabolic formation of DHP-derived DNA adducts from a representative otonecine type pyrrolizidine alkaloid clivorine and the extract of Ligularia hodgsonnii hook.

Plants that contain pyrrolizidine alkaloids (PAs) are widely distributed, and PAs have been shown to be genotoxic and tumorigenic in experimental animals. Our recent mechanistic studies indicated that riddelliine, a tumorigenic retronecine type PA, induced tumors via a genotoxic mechanism mediated by the formation of a set of eight 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-derived DNA adducts. However, it is not known if this mechanism is general to PAs of other types. In this study, we report that the metabolism of clivorine, a tumorigenic otonecine type PA, by F344 rat liver microsomes results in DHP formation. When incubations were conducted with clivorine in the presence of calf thymus DNA, eight DHP-derived DNA adducts were formed. The Ligularia hodgsonnii Hook plant, an antitussive traditional Chinese medicine, was found to contain otonecine type PAs with clivorine being predominant. DHP and DHP-derived DNA adducts were also obtained when microsomal incubations were conducted with extracts of L. hodgsonnii Hook. This is the first report that DHP-derived DNA adducts are formed from the metabolic activation of otonecine type PA and that these DHP-derived DNA adducts are potential biomarkers of PA exposure and PA-induced tumorigenicity. These results also provide evidence that the principal metabolic activation pathway of clivorine leading to liver genotoxicity and tumorigenicity is (i) formation of the corresponding dehydropyrrolizidine (pyrrolic) derivative through oxidative N-demethylation of the necine base followed by ring closure and dehydration and (ii) binding of the pyrrolic metabolite to DNA leading to the DNA adduct formation and tumor initiation.

Animals↗

Pyrrolizidine alkaloids--genotoxicity, metabolism enzymes, metabolic activation, and mechanisms.

Pyrrolizidine alkaloid-containing plants are widely distributed in the world and are probably the most common poisonous plants affecting livestock, wildlife, and humans. Because of their abundance and potent toxicities, the mechanisms by which pyrrolizidine alkaloids induce genotoxicities, particularly carcinogenicity, were extensively studied for several decades but not exclusively elucidated until recently. To date, the pyrrolizidine alkaloid-induced genotoxicities were revealed to be elicited by the hepatic metabolism of these naturally occurring toxins. In this review, we present updated information on the metabolism, metabolizing enzymes, and the mechanisms by which pyrrolizidine alkaloids exert genotoxicity and tumorigenicity.

Animals↗

Simultaneous determination of the major isosteroidal alkaloids and their glucosides in the bulbs of Fritillaria by high performance liquid chromatography coupled with evaporative light scattering detection.

AIM: To establish an HPLC-ELSD method for the simultaneous determination of five major bioactive isosteroidal alkaloids and gluco-alkaloids in the bulbs of Fritillaria namely peimissine, imperialine, sinpeinine A, imperialine-3 beta-glucoside and yibeinoside A. METHODS: A Nova-Pak C18 column (150 mm x 3.9 mm ID) was used. The chromatography was carried out with a linear gradient programming. The mobile phase was acetonitrile-water (containing 0.1% diethylamine) and the flow rate was 1.0 mL.min-1. RESULTS: The linear range of peimissine was 13.1-288.2 mg.L-1 (r2 = 0.9975), imperialine-3 beta-glucoside 7.7-169.4 mg.L-1 (r2 = 0.9993), yibeinoside A 7.3-160.6 mg.L-1 (r2 = 0.9997), imperialine 16.5-363.0 mg.L-1 (r2 = 0.9992), sinpeinine A 8.7-191.4 mg.L-1 (r2 = 0.9942). CONCLUSION: The method is accurate with overall intra- and inter-day variation less than 5% and recovery more than 95%. The method was successfully applied to analyze five major bioactive alkaloids and gluco-alkaloids in three Fritillaria bulbs.

Alkaloids↗

[Screening of differential genes between human embryonic stem cell and differentiated cell].

It is one of the core questions that how human embryonic stem cell (hESC) maintain the undifferentiated state during the propagation process. The current advance in answering this question included the studies on LIF signal transduction, Oct-4 factor and Nanog gene. But the question is far from being elucidated. In order to further understand the mechanism of maintaining the undifferentiated state of hESC, we screened out the expressed sequence tags (ESTs) which expressed highly in hESC but expressed lowly or unexpressed in the differentiated hESC's clones (dhESC) by suppression subtractive hybridization (SSH) and cDNA dot blot techniques. One hundred and five putative positive clones were screened out to be sequenced and were compared with the GenBank. Among them, seventy six clones represented sixty one identified genes that shared high homology with sequences in GenBank. Eighteen clones represented fifteen hypothetic genes, and eleven clones were function-unknown. Eight clones were picked out to analyze using semi-quantitative RT-PCR, the results confirmed that the expression of seven clones among them were higher in the hESC, and lower or no expression in the dhESC. The results showed that many differentiated expressed genes were involved before and after hESC's differentiation. Further functional analysis to those genes that expressed highly in the undifferentiated hESC and lowly in the dhESC might provide a basis to understand the mechanism of maintaining the undifferentiated state of hESC.

Cell Differentiation↗

[Study on fingerprint of rhizoma chuanxiong by HPLC-DAD-MS].

AIM: To establish a high performance liquid chromatographic fingerprint for the quality control of rhizoma Chuanxiong, a traditional Chinese medicine derived from the root of Ligusticum chuanxiong Hort.. METHODS: An on-line optimized HPLC-DAD-MS technique was employed. The HPLC analysis was performed on a Waters Symmetry C18 column (150 mm x4. 6 mm ID, 5 microm) with a Waters Spherisorb S5 ODS2 (10 mm x 4.6 mm) guard column. The mobile phase consisted of A (methanol) and B (0.25% acetic acid). Components were separated using the following gradient profile: 32% B at 0-3 min, 32%-85% B at 3-33 min, 85%-100% B at 33-52 min; flow rate was 0.7 mL x min(-1). DAD was set from 190 to 400 nm, the fingerprint was monitored at 294 nm. All mass spectra were acquired in the positive ion mode with electrospray ionization; the full scan mass spectrum was recorded over the range of m/z 100-800. Nine samples from three companies were analyzed; the main characteristic peaks were identified based on the comparison of UV and MS spectra of each analyte with that of authentic compounds and literature data. RESULTS: The HPLC fingerprint was established based on the analysis of nine rhizoma Chuanxiong herbal samples supplied by three companies. Twenty-one characteristic peaks were found in all nine samples. These peaks were classified into four groups: group I at 0-12 min, three peaks were found, and the marker peak 3 was confirmed as ferulic acid; group II at 12-24 min, four peaks were found, and the marker peaks 4 and 5 were identified as senkyunolide I and senkyunolide H; group III at 24-32 min, there were seven peaks, and the marker peaks 9, 11, 13 and 14 were elucidated as senkyunolide A, coniferylferulate, ligustilide and 3-butylidenephthalide, respectively; group IV at 32-50 min, seven peaks were observed, and the marker peaks 15 and 17 were identified as riligustilide and levistolide A. The peak areas of 13 main peaks with normalized peak area (1% were determined. Using the most abundant peak 13 as the reference peak, the calculated relative retention times (tR of the characteristic peak/tR of the reference peak) among nine samples were consistent (RSD < or = 1%), while the calculated relative peak areas (peak area of the characteristic peak/peak area of the reference peak) among nine samples were significantly different (P < 0.001), indicating that all nine samples tested contain similar 13 main components with different quantities. CONCLUSION: The established HPLC fingerprint is very specific, and can be used to evaluate the quality consistency of different rhizoma Chuanxiong herbs.

Chromatography, High Pressure Liquid↗

[Molecular cloning and characterization analysis of HPESCRG1, a novel gene expressed specifically in human embryonic stem cell].

OBJECTIVE: To clone a novel gene expressed specifically in human embryonic stem cell and to analyze its characteristics. METHODS: Based on an expression sequence tags(EST) CF948547 which expressed specifically in human embryonic stem cell, the full-length cDNA sequence of a novel gene was cloned by using bioinformatic and molecular biological technique. Its expression profile was analyzed by reverse transcription-polymerase chain reaction(RT-PCR), and subcellular location was determined by enhanced green fluorescent protein (EGFP) eukaryotic expression system. RESULTS: A novel gene HPESCRG1(homo sapiens pluripotent embryonic stem cell-related gene) was cloned successfully. Its GenBank accession number was AY283672. Its cDNA length was 1395 bp. It comprised 9 exons and 8 introns, and its opening reading frame was 250-1146 bp. Its chromosomal mapping was located in 3q13.13, and the putative protein contained 297 amino acids. The theoretical molecular weight of the putative protein was 33 784 and the isoelectric point was 9.35. The protein primary structure of this gene contained a SAP motif and it was subcellularly located in nuclei. Expression analysis showed that this gene was expressed specifically in human ES cells, but not expressed in the adult human tissues, the multiple tissues of embryo aborted in over 5 months' pregnancy, the differentiated cells of HESC-1, and the human mesenchymal stem cells (hMSCs) and human embryonic fibrocytes (hEFCs). CONCLUSION: HPESCRG1 was found to be a novel gene expressed specifically in human ES cell, which might be related to self-renewal of human ES cell and maintaining its undifferentiated state.

Amino Acid Sequence↗

Genetic changes in human fetuses from spontaneous abortion after in vitro fertilization detected by comparative genomic hybridization.

The in vitro fertilization (IVF) technique is becoming a very important approach for infertile disease therapy, but approximately 30% of pregnancies are spontaneously aborted in the first trimester. It is believed that chromosomal abnormality is the major reason for early spontaneous abortion. Although some reports have mentioned cytogenetic changes in spontaneously aborted embryos after IVF, little is known about the comprehensive cytogenetic alterations in these aborted embryos. Here we use the comparative genomic hybridization (CGH) technique to analyze the genetic alterations in 41 spontaneously aborted human specimens after IVF. In this study, 25 of 41 cases (61%) showed chromosomal changes. Among them, autosomes and sex chromosomes were involved in 16 and 11 cases, respectively. Several nonrandom chromosomal changes were identified, including loss of one sex chromosome (six cases) and gains of 22 (four cases), Y (four cases), 21 (three cases), 4 (two cases), and 13 (two cases). Our data support the opinion that chromosome abnormality is one of the major causes of early spontaneous abortion after IVF. The association between chromosome changes in these spontaneously aborted fetuses and maternal age, infertility patterns, infertility causes, and IVF patterns (routine IVF and other methods, including intracytoplasmic sperm injection, egg donation, and embryo donation) were also studied. No significant correlation was found.

Abortion, Spontaneous↗

Gender differences in microsomal metabolic activation of hepatotoxic clivorine in rat.

The gender differences in the in vitro microsomal metabolic activation of hepatotoxic clivorine, a representative naturally occurring hepatotoxic otonecine type pyrrolizidine alkaloid, in Sprague-Dawley rats and their relation to the gender differences in susceptibility to clivorine intoxication were reported in the present study. Clivorine-induced liver damage in the male rat via metabolic activation to form the reactive pyrrolic ester followed by covalent binding to liver tissue constituents has been reported previously by our research group. The present study demonstrated, for the first time, that cytochromes p450 3A1 and 3A2, which are constitutively expressed in the male rat, might play a significant role in the metabolic activation of clivorine in the rat. Thus, in the male rat, the metabolic activation by liver microsomes to form the reactive pyrrolic ester was found as the only direct metabolic pathway of clivorine followed by subsequent formation of the toxic tissue-bound pyrroles leading to hepatotoxicity. In the case of the female rat, a less significant metabolic activation was observed, whereas the formations of two novel nonpyrrolic metabolites were determined as the predominant biotransformations. None of the four cDNA-expressed rat enzymes (cytochrome p450 2C12, 2E1, 3A1, 3A2) tested could catalyze the formation of these two new metabolites. Furthermore, the female rat (LD(50) = 114 +/- 9 mg/kg, i.p.) was found to be significantly less susceptible to clivorine intoxication than the male rat (LD(50) = 91 +/- 3 mg/kg, i.p.). Therefore, the results suggested that a significantly lower metabolic activation due to the lack of cytochrome p450 3A1 and p450 3A2 activities mainly accounted for the smaller susceptibility of the female rat to clivorine intoxication.

Animals↗

Simultaneous analysis of seventeen chemical ingredients of Ligusticum chuanxiong by on-line high performance liquid chromatography-diode array detector-mass spectrometry.

An on-line high performance liquid chromatography (HPLC)-diode array detector (DAD)-mass spectrometry (MS) analytical method has been developed to simultaneously separate and identify seventeen main constituents of Chuanxiong ( Ligusticum chuanxiong Hort.), a traditional Chinese medicinal herb. In three Chuanxiong samples, nine compounds were unequivocally determined as vanillin (1), ferulic acid (2), senkyunolide I (4), senkyunolide H (5), senkyunolide A (6), coniferyl ferulate (7), Z-ligustilide (8), neocnidilide (9) and 3-butylidenephthalide (10) by comparing their t R, UV, and MS data with those obtained for the authentic compounds. Furthermore, additional eight compounds were tentatively identified as senkyunolide J (11), senkyunolide F (12), 3-butylphthalide (13), cnidilide (14), riligustilide (15) or Z,Z'-6,8',7,3'-diligustilide (16), tokinolide B (17), levistolide A (18) and senkyunolide P (19), based on their MS data and the comparison of their UV spectra with the published references. This is the first report to describe the development of an on-line HPLC-DAD-MS method to simultaneously analyse seventeen main constituents present in Chuanxiong and to construct the chemical profiles of various Chuanxiong samples.

Chromatography, High Pressure Liquid↗

Antitussive activity of Stemona alkaloids from Stemona tuberosa.

Bioactivity-directed fractionation of the crude extract of Stemona tuberosa led to the isolation and characterization of four new stenine-type Stemona alkaloids, namely tuberostemonine J ( 2), tuberostemonine H ( 3), epi-bisdehydrotuberostemonine J ( 4) and neostenine ( 5), together with the known neotuberostemonine ( 1). These five isolated alkaloids were examined for antitussive activity in guinea pig after cough induction by citric acid aerosol stimulation. In this report, we demonstrated, for the first time, that compounds 1 and 5 showed significant antitussive activities. Further study of the structure-activity relationship on these isolated alkaloids and two synthetic analogues revealed that the saturated tricyclic pyrrolo[3,2,1- jk] benzazepine nucleus is the primary key structure contributing to the antitussive activity and all cis configurations at the three ring junctions are the optimal structure for the antitussive activity of stenine-type Stemona alkaloids.

Alkaloids↗

[Diagnosing achondroplasia by single cell nested-PCR].

OBJECTIVE: To research on the reliability of diagnosing achondroplasia (ACH) on single cell level and to provide a basis for preimplantation genetic diagnosis(PGD). METHODS: The high-frequency mutation region G380R of fibroblast growth factor receptor 3(FGFR3) gene was amplified by nested-PCR with single lymphocyte and single blastomere. The products of PCR were digested by restriction enzyme Bfm I, then the digested products were detected by 10% polyacrylamida gel electrophoresis(PAGE). RESULTS: The amplification success rate, allele dropout rate and correct diagnosis rate of single lymphocyte's PCR were 90.4%, 8.2% and 91.8%,respectively. The amplification success rate of single blastomere was 75.4%. CONCLUSION: The diagnosis of ACH by single cell nested-PCR is comparatively stable and reliable.

Achondroplasia↗

Species differences in the in vitro metabolic activation of the hepatotoxic pyrrolizidine alkaloid clivorine.

Clivorine is a representative naturally occurring hepatotoxic otonecine-type pyrrolizidine alkaloid. Our previous study has demonstrated that clivorine induces liver damage via metabolic activation to form the reactive pyrrolic ester followed by covalent binding to liver tissue constituents. The present study investigated species differences in the in vitro metabolic activation of clivorine in the male rat and guinea pig of both sexes. In the male rat, the activation of clivorine to form the reactive pyrrolic ester was found as the only metabolic pathway. Moreover, the toxic tissue-bound pyrroles and four isolatable metabolites identified, namely DHR, 7-GSH-DHR, 7,9-diGSH-DHR, and clivoric acid, were all generated from further metabolism of this reactive intermediate. In the case of both sexes of guinea pig, the same activation was observed as the minor biotransformation, while an additional metabolic pathway, a direct hydrolysis of clivorine to form novel clivopic acid was identified as the predominant detoxification pathway. Furthermore, the formation rates for the toxic tissue-bound pyrroles and less toxic DHR were significantly slower and higher, respectively, compared with those in the male rat. In addition, the formation of the reactive pyrrolic ester was mediated by the CYP3A subfamily in both animals, while carboxylesterases might be responsible for the detoxification hydrolysis in guinea pig. The results suggest that the higher metabolic rates for detoxification hydrolyses and the lower formation rate for the toxic tissue-bound pyrroles play the key roles in guinea pig resistance to clivorine intoxication. Therefore, the male rat and guinea pig should be the suitable animal models for further studies of bioactivation and deactivation of otonecine-type PA, respectively.

Animals↗

The extraction of imperialine and imperialine-3 beta-glucoside from Fritillaria pallidiflora Schrenk and quantitative determination by HPLC-evaporative light scattering detection.

The extraction procedure and quantitative determination by HPLC-evaporative light scattering detection (ELSD) of the main bioactive components, namely, imperialine (1) and imperialine-3 beta-glucoside (2), of bulbs of Fritillaria pallidiflora Schrenk have been investigated. The most efficient method for the simultaneous extraction of 1 and 2 involved pre-treatment of the bulb powder with ammonia, followed by reflux with dichloromethane:methanol at 90 degrees C for 4 h. Simultaneous determination of non-chromophoric 1 and 2 by HPLC-ELSD employed a Kromasil C18 column eluted with acetonitrile:water:diethylamine. The assay was accurate and reproducible with an overall variation lower than 4% and a sample recovery higher than 98%. The methods described have been successfully used to evaluate the quality of three batches of the crude traditional Chinese medicinal herb derived from the bulbs of F. pallidiflora.

Alkaloids↗