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Yi Li

Publications and source records attributed to Yi Li.

At least 289 records · Page 16Linked to original sources
PubMed2002

Plant expansins are a complex multigene family with an ancient evolutionary origin.

Expansins are a group of extracellular proteins that directly modify the mechanical properties of plant cell walls, leading to turgor-driven cell extension. Within the completely sequenced Arabidopsis genome, we identified 38 expansin sequences that fall into three discrete subfamilies. Based on phylogenetic analysis and shared intron patterns, we propose a new, systematic nomenclature of Arabidopsis expansins. Further phylogenetic analysis, including expansin sequences found here in monocots, pine (Pinus radiata, Pinus taeda), fern (Regnellidium diphyllum, Marsilea quadrifolia), and moss (Physcomitrella patens) indicate that the three plant expansin subfamilies arose and began diversifying very early in, if not before, colonization of land by plants. Closely related "expansin-like" sequences were also identified in the social amoeba, Dictyostelium discoidium, suggesting that these wall-modifying proteins have a very deep evolutionary origin.

Amino Acid Sequence↗
PubMed2002

The use of frailty hazard models for unrecognized heterogeneity that interacts with treatment: considerations of efficiency and power.

Increasingly, genetic studies of tumors of the same histologic diagnosis are elucidating subtypes that are distinct with respect to clinical endpoints such as response to treatment and survival. This raises concerns about the efficiency of using the simple log-rank test for analysis of treatment effect on survival in studies of possibly heterogeneous tumors. Furthermore, such studies, designed under the assumption of homogeneity, may be severely underpowered. We derive analytic approximations for the asymptotic relative efficiency of the simple log-rank test relative to the optimally weighted log-rank test and for the power of the simple log-rank test when applied to subjects with unobserved heterogeneity, as reflected in a continuous frailty, that may interact with treatment. Numerical studies demonstrate that the simple log-rank test may be quite inefficient if the frailty interacts with treatment. Further, there may be a substantial loss of power in the presence of the frailty with or without an interaction with treatment.

Brain Neoplasms↗
PubMed2002

Modeling spatial survival data using semiparametric frailty models.

We propose a new class of semiparametric frailty models for spatially correlated survival data. Specifically, we extend the ordinary frailty models by allowing random effects accommodating spatial correlations to enter into the baseline hazard function multiplicatively. We prove identifiability of the models and give sufficient regularity conditions. We propose drawing inference based on a marginal rank likelihood. No parametric forms of the baseline hazard need to be assumed in this semiparametric approach. Monte Carlo simulations and the Laplace approach are used to tackle the intractable integral in the likelihood function. Different spatial covariance structures are explored in simulations and the proposed methods are applied to the East Boston Asthma Study to detect prognostic factors leading to childhood asthma.

Asthma↗
PubMed2002

[Establishment of permanent lymphoblastoid cell lines of 47 patients with abnormal chromosome karyotype].

To increase the efficiency of in vitro transformation of human lymphocytes by Epstein-Barr virus (EBV) and establish permanent lymphoblastoid cell lines from patients with abnormal chromosome karyotype, B lymphoid cells were prepared from cryopreserved heparinized blood samples. The lymphoid cell pellet was resuspended with 0.5 ml medium of RPMI with 20% fetal calf serum(FCS), and added 2 ml virus-containing superatant of the EB virus-producing cell lines by filtrated, and mixed. Four 25 cm2 cell culture bottles were put upright. A total of 2.5 ml of RPMI with 20% FCS was put in each of them. The blood-virus mixture was distributed among the four cell culture bottles as follows: Bottle I, Bottle II, Bottle III and Bottle IV were added with 0.3 ml, 0.6 ml, 1.2 ml and the rest respectively. The cells culture bottles were put into the cell culture incubator in an upright position. After 3 days the cells were puting new medium with 20% FCS as follows: Bottle I 3 ml, Bottle II 4 ml, Bottle III 5 ml and Bottle IV 6 ml. After one week, the medium was changed again as described above. The medium change was conducted until the cells grew very fast. The right ratio between blood cells and virus titer can not be exactly determined for every blood sample, and therefore a dilution series with four different blood/virus ratios was set up. Due to the dilution series, addition of immune inhibitors like cyclosporine, was not necessary. Forty-seven permanent lymphoblastoid cell lines of patients with abnormal chromosome karyotype. Transformed cells were found in only one or two of the four cell culture bottles. The total successive rate increased up to 97.87%. Of the four cell culture bottles, Bottle I, Bottle II, Bottle III and Bottle IV, the successive rates were 6.39%, 61.70%, 31.91% and 8.51% respectively. This method can be used for preserving large number of lymphoblastoid cell lines, and also provide enough research materials for further studies.

Cell Line, Transformed↗
PubMed2002

Intravenous administration of human umbilical cord blood reduces neurological deficit in the rat after traumatic brain injury.

We measured the effect of treatment of traumatic brain injury (TBI) in the rat with human umbilical cord blood (HUCB) administered i.v.. HUCB cells were injected into the tail vein 24 h after TBI and the rats were sacrificed at day 28 after the treatment. The Rotarod test and the neurological severity score (NSS) were used to evaluate neurological function. The distribution of the donor cells in the brain, heart, lung, kidney, liver, spleen, bone marrow, and muscle were analyzed in recipient rats using immunohistochemical staining and laser confocal microscopy. HUCB cells injected i.v. significantly reduced motor and neurological deficits compared with control groups by day 28 after the treatment. The cells preferentially entered the brain and migrated into the parenchyma of the injured brain and expressed the neuronal markers, NeuN and MAP-2, and the astrocytic marker, GFAP. Some HUCB cells integrated into the vascular walls within the boundary zone of the injured area. Our data suggest that i.v. administration of HUCB may be useful in the treatment of TBI.

Animals↗
PubMed2002

Detection of occult metastases in lymph nodes from patients with colorectal carcinoma by reverse transcriptase-polymerase chain reaction.

OBJECTIVE: To detect occult metastases in lymph nodes from patients with colorectal carcinoma and its clinical significance. METHODS: The metastases in 260 lymph nodes from 39 histologically verified colorectal cancer patients were studied by both hematoxylin-eosin (HE) staining and cytokeratin-20 (CK20) specific RT-PCR. Ten normal lymph nodes were served as negative controls, and HT29 colon cancer cell line and 5 colorectal cancer specimens as positive controls. RESULTS: Ten normal lymph nodes were CK20-negative, HT29 cells and 5 tumor specimens were all CK20-positive. All 29 lymph nodes from 16 patients which confirmed metastases by HE staining exhibited CK20 positive expression; an additional 28 lymph nodes from 5 patients with no histologically detectable metastases expressed CK20 mRNA, i.e. presence of metastases. The difference of the positivity was significant (11.1% vs 21.9%, P < 0.01). According to the HE staining, the cases of Dukes' A, B, C and D were 3, 20, 12 and 4, respectively. In the 20 patients of Dukes' B stage, 5 of them had CK20-positive lymph nodes. CONCLUSION: CK20-specific RT-PCR is a highly sensitive, specific and simple method for detecting occult metastases in lymph nodes. The detection of CK20 mRNA expression in lymph nodes is recommended to precisely determine tumor stage and postoperative adjuvant therapy for patients with colorectal cancer, and further studies should be done in future to confirm the findings.

Adult↗
PubMed2002

[Effects of different frequency electromagnetic fields on the differentiation of midbrain neural stem cells].

Objective. To examine the effect of electromagnetic fields (EMF) (20 Hz, 8 mT; 5 Hz, 8 mT) on the neuron-orientated differentiation of neural stem cells (NSCs) from midbrains of new-bom rats. Method. Differentiated NSCs were exposed to EMF for 2 x 15 min per day lasting for I d, 5 d, or 10 d. The sham-exposure controls were correspondingly established. Cells were fixed and processed for immunofluorescent staining using the antibody against neuron-specific marker MAP2, then the percentage of MAP2+ cells was calculated. Result. The two EMFs promoted the differentiation of a neuronal fate in different ways. Both of them came into effect even after 1 d exposure. When cells exposed to the 20 Hz EMF, the percentage of neuron-orientated cells gradually increased with longer-term exposure and the most significant effect appeared in 10 d group while that happened in 5 d group under the condition of 5 Hz EMF. The effect contrasted horizontally, significant differences between the two EMFs were observed only at 10 d groups, 20 Hz EMF having more favorable effect than 5 Hz EMF. Conclusion. 20 Hz and 5 Hz EMF could promote the differentiation of midbrain NSCs to a neuronal phenotype in different ways, suggesting that the physical induction might be another strategy to manipulate the differentiation of NSCs.

Animals↗
PubMed2002

[Influence of P-glycoprotein expression on chemotherapeutic response of metastatic breast carcinoma].

BACKGROUND & OBJECTIVES: The clinical study showed that the P-glycoprotein(P-gp) expression was closely associated with the chemotherapeutic effect, response rate, prognosis, and survival time. Until now, few clinical papers have reported about metastatic sites and its response to chemotherapy with P-gp expression in metastatic breast carcinoma. The current study was designed to investigate the role of P-gp expression and its clinical value of chemotherapy for the patients with different metastatic sites of this carcinoma. METHODS: P-gp expression in 46 postoperative patients with metastatic breast carcinoma was detected by SABC immunohistochemical method. 43 cases treated with combination regimen: Cyclophosphamide 600 mg/m2 i.v. on day 1, Pirarubicin 60 mg/m2 i.v. on day 1, 5-Fluorouracil 600 mg/m2 i.v. on days 1 and 8. Repeat the cycle every 3 weeks for at least 2 cycles. The correlation between P-gp expression and chemotherapeutic response was analyzed. RESULTS: 1) P-gp expression positive rate was 56.5%, the P-gp expression in the patients with lung or liver viscera metastasis was higher than that in skin or lymph node metastasis (P = 0.049). 2) The overall response rate was 58.1% in 43 patients. The response rate of the P-gp negative group was higher than the P-gp positive group(P < 0.01). 3) The response rate in the patients with skin and lymph node metastasis was higher than the patients with lung and liver metastasis (P < 0.05). 4) The postoperative patients who had received CAF(cyclophosphamide + adriamycin + 5-fluorouracil) or CMF(cyclophosphamide + methotrexate + 5-fluorouracil) regimen adjuvant chemotherapy previously, the response rate of metastatic diseases to chemotherapy had no significant difference (P > 0.05). CONCLUSIONS: P-gp expression may be considered as an index for evaluating multidrug resistance, guiding drug use, and judging prognosis of the patients with metastatic breast carcinoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2002

[Chemotactic peptide fMLP enhances antitumor activity of boanmycin].

BACKGROUND & OBJECTIVE: Boanmycin (BAM), a single A6 component of the bleomycin complex, is effective against a panel of cancers in clinical trials. Chemotactic peptide can activate and attract leukocytes and macrophages that may interfere with the process of tumor growth, invasion, and metastasis. This study was designed to investigate the antitumor activity of BAM in combination with chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine(fMLP). METHODS: Cytotoxicity of BAM and fMLP to tumor cells was determined by MTT assay, particularly in presence of macrophages. Therapeutic effect was evaluated by using the model of subcutaneously transplanted hepatoma 22 in mice. RESULTS: In vitro experiment showed that BAM and fMLP had no synergism in cytotoxicity to tumor cells. However, in the presence of macrophages, BAM at concentrations of 10, 30, and 100 micrograms/ml in combination with fMLP 20 micrograms/ml displayed synergistic effect in cytotoxicity. In all in vivo experiments, fMLP administered peritumorally 3 times at the dose of 1 mg/mouse showed no significant growth inhibition. Three settings of BAM and fMLP combination included: (1) BAM, administered peritumorally x 3, was started 24 h after tumor inoculation. BAM (0.5 mg/kg) alone and BAM-fMLP combination inhibited the growth of hepatoma 22 by 26.6% and 64.7%, respectively (P < 0.05, CDI = 0.36) on day 13. (2) BAM, administered i.p. x 3, was started 24 h after tumor inoculation. The tumor growth in BAM (1 mg/kg) group was faster than that in BAM-fMLP combination group. On day 14, BAM (1 mg/kg) alone and BAM-fMLP combination suppressed the tumor growth by 11% and 70.6%, respectively (P < 0.05, CDI = 0.42). (3) BAM, administered i.p. x 3, was started 96 h after tumor inoculation. The tumor growth in BAM (1 mg/kg) group was faster than that in BAM-fMLP combination group. On day 13, BAM (1 mg/kg) alone and BAM-fMLP combination suppressed the tumor growth by 38.2% and 77.1%, respectively (P < 0.05, CDI = 0.51). As shown in all in vivo experimental settings, antitumor effect of BAM in combination with fMLP was much more potent than that of BAM alone. CONCLUSION: This experiment shows that chemotactic peptide fMLP may enhance the antitumor effect of BAM and the enhancement may need the participation of macrophages. Chemotactic modulation may play a role in cancer chemotherapy.

Animals↗
PubMed2002

[Significance of cytokeratin gene (CK-20 mRNA) expression in metastatic lymph nodes in colon carcinoma patients].

OBJECTIVE: To elucidate the significance of detecting cytokeratin gene (CK-20 mRNA) expression in metastatic lymph nodes of colon carcinoma patients. METHODS: The expression of CK-20 mRNA was detected in 342 lymph nodes by reverse transcription-polymerase chain reaction (RT-PCR) in 49 colon carcinoma patients. Its incidence was compared with that by routine pathologic examination. RESULTS: The positive rates of detecting metastasis in the lymph nodes were 21.9% by RT-PCR and 11.1% by routine pathologic examination. CONCLUSION: The detection of cancer metastasis in the lymph nodes in colon carcinoma is almost doubled (21.9% vs 11.1%) by CK-20 mRNA, which may provide a guiding significance in staging, treatment planning and prognosis in the prognostic estimation of colon carcinoma patients.

Adult↗
PubMed2002

[Induction of petal-like structures from petals of Crocus sativus L. and the differentiation of style-stigma-like structures in vitro].

Firstly the petal of Crocus sativus L was cultured on the medium that supplemented with different combinations of hormones. The petal-like structures(PLS) were induced on medium, but the induction rates were different in various medium. The highest induction rate of petal-like structures was obtained on the media that was supplemented with NAA (4 mg/L) and KT (8 mg/L). The petal-like structures were subcultured on another media when the structure was produced on the explants and proliferate groups. The later media was used for inducing style-stigma-like structures(SSLS). The induction rate of style-stigma-like-structures in the petal-like structures group is much higher than the rate in the preceding work, and the maximum of style-stigma-like structures produced per explant was 30. The best result of style-stigma-like structures was observed on the petal-like structure groups which came from the third treatment. The differentiation rate of style-stigma-like structures is stable in the subcultures of petal-like structures. The result revealed that the induction frequency of style-stigma-like structures formed on the petal-like structures is higher than that form on the petals of C. sativus L.

Cell Differentiation↗
PubMed2002

[Genetic polymorphism of six STR loci in the Han population in Henan province].

To investigate the allele frequencies of six short tandem repeats (STR) loci: F13A1, F13B, D8S1179, CSF1PO, D5S818 and TPOX in Han population in Henan province, DNA was extracted with chelex from EDTA-blood samples of the unrelated individuals in Henan province and amplified with PCR technique. The PCR product was analyzed with the undenatured PAGE vertical electrophoresis and silverstain. The results were obtained through genetical analysis. The authors got the number of allele of six loci, Three alleles of F13A1 could be detected in this population. The F13A1 * 7 is the most common allele with a frequency of 45.2%, followed by F13A1 * 5 and F13A1 * 4 respectively. F13B had four alleles among which F13B * 10 has the highest frequency, followed by F13B * 9, F13B * 8, F13B * 11. The 8 alleles of D8S1179 in the order from high to low frequency is D8S1179 * 14, * 15, * 12, * 11, * 10. And the most common frequencies of alleles of CSF1PO, D5S818, TPOX ore CSF1PO * 12, D5S818 * 11, TPOX * 8, respectively followed by the allele of * 11, * 14, * 10, * 13 in CSF1PO locus, and * 12, * 13, * 10, * 9, * 14, * 8, * 15, * 7 in D5S818 locus, * 11, * 9, * 12, * 10 in TPOX locus. The heterozygosities of the six loci were 0.62, 0.46, 0.83, 0.59, 0.78 and 0.65; the discrimination powers were 0.78, 0.66, 0.95, 0.79, 0.92 and 0.82. The heterozygosities of the six loci are high and the frequencies are in good agreement with Hardy-Weinberg equilibrium. The six loci are good as genetic markers. We can use these loci in dividualidentification and partenity test in forensic area.

Alleles↗
PubMed2002

[Extraction of ecdysterone from Stemmacantha uniflora].

OBJECTIVE: To optimize the conditions for the extraction of ecdysterone from Stemmacantha uniflora. METHODS: Conditions for the extraction were studied by three different methods as guided by the content of ecdysterone and solid material that present in the extract. RESULTS: Methanol was the best solvent, water the second, ethanol was greatly effected by concentration. Ultrasonic extraction had a good efficiency with short time. The time of cool extraction was too long, its efficiency was inferior to the other methods. CONCLUSION: The best methods for the extraction of ecdysterone from Stemmacantha uniflora was methanol reflux extraction.

Asteraceae↗
PubMed2002

[Microbiological eco-regulation in Vc two-step fermentation].

The growth and interaction of Gluconobacter axydans and Bacillus megaterium in Vc two step fermentation have been studied. The results showed that there is a kind of coordinate symbiosis between G. axydans and B. megaterium during the fermentation, which could promoted 2-Keto-L-gulonic acid (2KGA) synthesis. The efficiency on the synbiosis would vary as the conditions of fermentation were different and were improved by the environmental factors.

Bacillus megaterium↗
PubMed2002

[High density fed-batch culture of Escherichia coli DH5 alpha/pDH-B2m with DO feed-back control of nutrient feeding].

Optimization of cultivation condition of recombinant E. coli DH5 alpha/pDH-B2m and the condition suitable for expression of recombinant mature peptide of human bone morphogenetic protein-2 was carried out in 500 mL shaking flasks and then transferred to NBS Bioflo IV, a 20 L DO feed-back fed-batch culture system, to obtain rhBMP-2. The results indicate that keeping dissolved oxygen at 40% and controlling nutrient feeding rate with DO feed back strategy can obtain theoretically 3.59 g recombinant mature peptide of hBMP-2 per liter of broth, the final cell density OD600 reaches 57(22.8 g dry cell weight/L), and the expression of rhBMP-2 amounts to 30% of the total protein in E. coli.

Bone Morphogenetic Protein 2↗
PubMed2002

[Pathological observation on five autopsies of the alumina pneumoconiosis].

OBJECTIVE: To study the pathological characteristics and the morphological changes of alumina pneumoconiosis. METHODS: The pathological observation and analysis were performed in lungs of five autopsies with alumina pneumoconiosis. RESULTS: The early common pathological change of alumina pneumoconiosis was the dust spots. The dust fibrosis had two forms, one was the non-focal fibrous proliferation of interstitial space, the other was the proliferation of inner-dust-spot fibrosis that finally developed into non-typical pneumoconiosis nodules. CONCLUSION: The pathological characteristics of the alumina pneumoconiosis may not be all the same to those of aluminium and aluminium oxide pneumoconiosis. Alumina pneumoconiosis is a complex pneumoconiosis. The typical pathological changes are the dust-spot emphysema and dust fibrosis of interstitial tissue. Infection in lung and complication of lung tumor, especially pneumo-tubercolosis would promote dust fibrosis. The pleural thickening, the relationship between lung cancer and alumina dust should be taken seriously.

Aluminum Oxide↗
PubMed2002

[Genetic polymorphisms of human short tandem repeat vWA].

We researched the genetic polymorphisms of vWA in Henan population and its usefulness in forensic science.DNA extracted from non-relative persons in Henan population with Chelex was amplified by polymerase chain reaction and was typed by nondenaturing polyacrylamide gel electrophoresis silver staining.A total of 8 alleles and 19 genotypes were found in Henan population,its heterozygosity is high and the locus can be used in forensic genetics. We obtained the allelic frequency of the locus vWA in Henan population. The results of amniotic fluid,villus,blood stain indicate vWA is a good locus for forensic study.

English Abstract↗