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Biomedical subjects

Lin Liu

Publications and source records attributed to Lin Liu.

At least 109 records · Page 6Linked to original sources
PubMed2004

Telomerase deficiency impairs differentiation of mesenchymal stem cells.

Expression of telomerase activity presumably is involved in maintaining self-replication and the undifferentiated state of stem cells. Adult mouse bone marrow mesenchymal stem cells (mMSCs) are multipotential cells capable of differentiating into a variety of lineage cell types, including adipocytes and chondrocytes. Here we show that the lacking telomerase of mMSC lose multipotency and the capacity to differentiate. Primary cultures of mMSCs were obtained from both telomerase knockout (mTR(-/-)) and wild-type (WT) mice. The MSCs isolated from mTR(-/-) mice failed to differentiate into adipocytes and chondrocytes, even at early passages, whereas WT MSCs were capable of differentiation. Consistent with other cell types, late passages mTR(-/-)MSCs underwent senescence and were accompanied by telomere loss and chromosomal end-to-end fusions. These results suggest that in addition to its known role in cell replication, telomerase is required for differentiation of mMSCs in vitro. This work may be significant for further potentiating adult stem cells for use in tissue engineering and gene therapy and for understanding the significance of telomerase expression in the process of cell differentiation.

Adipocytes↗
PubMed2004

Behavioral characterization of wild derived male mice (Mus musculus musculus) of the PWD/Ph inbred strain: high exploration compared to C57BL/6J.

PWD/Ph is an inbred mouse strain derived from wild mice trapped in central Czech Republic. These mice are of the Mus musculus musculus subspecies, whose ancestors separated from those of Mus musculus domesticus about one million years ago. There is a high degree of variation in the genomic sequence and a wide range of phenotypes between PWD/Ph and standard laboratory inbred mouse strains, the genomes of which are principally Mus musculus domesticus in origin, making PWD/Ph mice an useful resource for complex trait research. As a first step in taking advantage of this resource, a preliminary characterization of the behavior of PWD/Ph mice was performed. Groups of 10 PWD/Ph and C57BL/6J male mice were tested in the open field, novel object exploration task and Morris water maze. PWD/Ph were marginally more anxious than C57BL/6J mice in the open field but subsequently displayed much higher levels of exploration and lower anxiety than C57BL/6J mice following introduction of a novel object. As C57BL/6J itself is rated as highly explorative among classical inbred strains, PWD/Ph probably represents an extreme among mouse strains for this specific behavior. PWD/Ph and C57BL/6J mice differed in their water escape training profiles in the Morris water maze, perhaps reflecting different motivational factors. However, there were no differences in overall cognitive ability (spatial learning) as both groups learned to find the hidden platform and performed equally well when the location of the platform was changed. This is the first quantification of the behavior of PWD/Ph mice and the results are promising for the potential of the consomic panel currently being generated with PWD/Ph and C57BL/6J as a tool for the molecular dissection of behavior.

Animals↗
PubMed2004

Effect of ploidy and parental genome composition on expression of Oct-4 protein in mouse embryos.

The transcription factor Oct-4 is expressed in germ cells and also is considered as a marker for pluripotency of stem cells. We first examined dynamics of Oct-4 protein expression during preimplantation development using both Western blot analysis, and immunofluorescence staining. We show that intact Oct-4 protein is not detected in either ovulated mature oocytes, or in zygotes and 2-4-cell embryos, which are the only known totipotent cell types in mammals. This finding is unexpected, since Oct-4 has been proposed to play a role in the control of totipotency. The results suggest that Oct-4 is not indispensable for fertilization and early cleavage. Rather, expression of Oct-4 protein is first detected in the nuclei of 8-16 cell morula, increases in early blastocysts, and declines in late blastocysts, in which most Oct-4 protein is confined to the inner cell mass (ICM) region, consistent with previous findings. We further compared Oct-4 protein expression in diploid and tetraploid blastocysts derived from normal fertilization or parthenogenesis, as well as expression in diploid androgenetic blastocysts. Expression levels and localization of Oct-4 protein are similar in both diploid and tetraploid early blastocysts, regardless of whether blastocysts are derived from fertilization or parthenogenesis. Androgenetic diploid blastocysts also express similar levels of Oct-4. Late blastocysts generated by both fertilization and parthenogenesis show a similar pattern of Oct-4 expression, suggesting that paternal genome activation is not required for Oct-4 expression. Expression of Oct-4 protein does not differ between diploid and tetraploid embryos, indicating that tetraploidy does not influence Oct-4 expression. Thus, expression of Oct-4 protein is initiated at morula stage in preimplantation embryos and completely controlled by a mechanism activated in oocytes. Downregulation of Oct-4 expression coincides with differentiation of trophectoderm. Similar profiles of Oct-4 expression observed in embryos with different ploidy and genome composition, are suggestive of Oct-4 being necessary but not sufficient for developmental potency.

Animals↗
PubMed2004

Reorganization of cytoskeleton during surfactant secretion in lung type II cells: a role of annexin II.

The secretion of lung surfactant requires the movement of lamellar bodies to the plasma membrane through cytoskeletal barrier at the cell cortex. We hypothesized that the cortical cytoskeleton undergoes a transient disassembly/reassembly in the stimulated type II cells, therefore allowing lamellar bodies access to the plasma membrane. Stabilization of cytoskeleton with Jasplakinolinde (JAS), a cell permeable actin microfilament stabilizer, caused a dose-dependent inhibition of lung surfactant secretion stimulated by terbutaline. This inhibition was also observed in ATP-, phorbol 12-myristate 13-acetate (PMA)- or Ca(2+) ionophore A23187-stimulated surfactant secretion. Stimulation of type II cells with terbutaline exhibited a transient disassembly of filamentous actin (F-actin) as determined by staining with Oregon Green 488 Phalloidin. The protein kinase A inhibitor, H89, abolished the terbutaline-induced F-actin disassembly. Western blot analysis using anti-actin and anti-annexin II antibodies showed a transient increase of G-actin and annexin II in the Triton X-100 soluble fraction of terbutaline-stimulated type II cells. Furthermore, introduction of exogenous annexin II tetramer (AIIt) into permeabilized type II cells caused a disruption in the cortical actin. Treatment of type II cells with N-ethylmaleimide (NEM) resulted in a disruption of the cortical actin. NEM also inhibited annexin II's abilities to bundle F-actin. The results suggest that cytoskeleton undergoes reorganization in the stimulated type II cells, and annexin II tetramer plays a role in this process.

Actins↗
PubMed2004

Genotyping pooled DNA on microarrays: a systematic genome screen of thousands of SNPs in large samples to detect QTLs for complex traits.

Large samples and systematic screens of thousands of DNA markers are needed to detect quantitative trait loci (QTLs) of small effect size. One approach to conduct systematic genome scans for association is to use microarrays which, although expensive and non-reusable, simultaneously genotype thousands of single-nucleotide polymorphisms (SNPs). This brief report provides proof of principle that groups of pooled DNA (for example cases and controls) can be genotyped reliably on a microarray. DNA was pooled for 105 Caucasian males and genotyped three times on microarrays for more than 10,000 SNPs (Affymetrix GeneChip Mapping 10K Array Xba 131). The average correlation was 0.973 between the allele frequency estimates for the three microarrays using the same DNA pool. The correlation was 0.923 between the average of the three microarray estimates using pooled DNA and individual genotyping estimates for a Caucasian population as provided by Affymetrix (NetAffx). Thus, genotyping pooled DNA on microarrays can provide a systematic and powerful approach for identifying QTL associations for complex traits including behavioral dimensions and disorders.

DNA↗
PubMed2004

Isolation of highly pure alveolar epithelial type I and type II cells from rat lungs.

There are no ideal cell lines available for alveolar epithelial type I and II cells (AEC I and II) at the present time. The current methods for isolating AEC I and II give limited purities. Here, we reported improved and reproducible methods for the isolation of highly pure AEC I and II from rat lungs. AEC I and II were released from lung tissues using different concentrations of elastase digestion. Macrophages and leukocytes were removed by rat IgG 'panning' and anti-rat leukocyte common antigen antibodies. For AEC II isolation, polyclonal rabbit anti-T1alpha (an AEC I apical membrane protein) antibodies were used to remove AEC I contamination. For AEC I isolation, positive immunomagnetic selection by polyclonal anti-T1alpha antibodies was used. The purities of AEC I and II were 91 +/- 4 and 97 +/- 1%, respectively. The yield per rat was approximately 2 x 10(6) for AEC I and approximately 33 x 10(6) for AEC II. The viabilities of these cell preparations were more than 96%. The protocol for AEC II isolation is also suitable to obtain pure AEC II (93-95%) from hyperoxia-injured and recovering lungs. The purified AEC I and II can be used for gene expression profiling and functional studies. It also offers an important tool to the field of lung biology.

Animals↗
PubMed2004

Effects of local administration of clodronate on orthodontic tooth movement and root resorption in rats.

Clodronate, a non-N-containing bisphosphonate, strongly inhibits bone resorption and also has anti-inflammatory properties. The purpose of this study was to examine the effect of the local administration of clodronate on orthodontic tooth movement. Both the right and left upper first molars of 26 7-week-old male Wistar rats were moved buccally with a standardized expansion spring. Clodronate solution was injected into the sub-periosteum area adjacent to the left upper molar every third day during the experimental period. The right first molar served as the control. Local injection of clodronate caused a significant (P < 0.001) and dose-dependent reduction in tooth movement in the rats. The number of osteoclasts on the clodronate-injected side was significantly less (P < 0.01) than on the control side. Local clodronate also inhibited root resorption incident to tooth movement. These results suggest that localized use of clodronate could be a useful therapeutic adjunct in orthodontic treatment.

Alveolar Process↗
PubMed2004

[A pilot study on the detection of sentinel lymph nodes in early stage cervical cancer].

OBJECTIVE: The purpose of this study was to investigate the clinical value of sentinel lymph node (SLN) detection in the management of early stage cervix cancer. METHODS: Twenty eight patients with early stage (Ia - IIa) cervix cancer undergoing radical hysterectomy and pelvic lymphadenectomy were included in the study. 37 Mbq (0.4 ml) (99m)Tc-labeled dextran ((99m)Tc-DX) was injected to the cervix at two locations (2 and 10 o'clock) 18 hours before the operation followed by preoperative lymphoscintigraphy to detect the SLNs. During the operation, SLNs were identified from dissected LN by gamma-counter. The samples of SLNs and non-SLNs (NSLN) were recorded separately and compared with the final pathology results. RESULTS: SLN was identified in 27 of 28 (96%) patients. A total of 123 SLNs were identified from 814 lymph nodes. Six (21%) patients had altogether 11 positive lymph nodes, which were all SLNs. No patient had false-negative SLNs. CONCLUSIONS: SLNs can successfully predict the lymphatic metastasis in patients with cervical cancer. The clinical validity of this technique should be further evaluated.

Adult↗
PubMed2004

[Expression and significance of telomerase reverse transcriptase and its regulators in non-small cell lung carcinoma].

BACKGROUND & OBJECTIVE: Telomerase is a ribonucleoprotein complex, which is silent in normal human somatic cells but may be reactivated by a series of regulators, and cause tumorigenesis. As a critical factor of telomerase activity, much progression has been achieved in the study of regulation of human telomerase reverse transcriptase, but the detail mechanism is still not clear. This study was designed to investigate the relationship of expression of human telomerase reverse transcriptase mRNA (hTERT mRNA) and its regulators including c-myc, mutant p53, protein kinase C alpha (PKCalpha) with clinicopathological significance of expression of the four markers in non-small cell lung carcinoma (NSCLC). METHODS: The expression of hTERT mRNA in 113 NSCLC specimens were detected by in situ hybridization, and the expression of c-myc, mutant p53, and PKCalpha in the same specimens were detected by immunohistochemistry. RESULTS: The positive rates of 113 NSCLC samples for hTERT mRNA, c-myc, mutant p53, and PKCalpha were 80.5%, 68.1%, 61.9%, and 85.0%, respectively. The differences were statistically significant among the expression of hTERT mRNA, c-myc, and PKCalpha (P< 0.05 or P< 0.01), but was not significant between the expression of mutant p53 and hTERT mRNA, c-myc as well as PKCalpha. The expression of mutant p53 was associated with carcinoma cell differentiation (P< 0.05), and its positive rate gradually increased with the extend of differentiation of carcinoma cell. The expression of hTERT mRNA, c-myc, and PKCalpha were not associated with carcinoma cell differentiation. There was no relationship of expression of the four markers with histological types, TNM stages, and lymph node metastasis status. CONCLUSION: C-myc and PKCalphawere associated with the expression of telomerase.

Adult↗
PubMed2004

[Inhibiting effects of stroma cell drived factor 1 (SDF-1) on proliferation of human acute myelocytic leukemia cell HL-60].

This study was aimed to investigate the importance of chemokine SDF-1 in maintaining proliferation ability of acute myelocytic leukemia cell line HL-60 when the effects of SDF-1 on HL-60 cell proliferation were inhibited. Marrow stromal cells were cultured and co-cultured with HL-60 cells, and SDF-1 activity was blocked with anti-CXCR4 McAb. HL-60 cell activity was detected by MTT while cell cycle and the expression of CXCR4 on HL-60 cell membrane were observed by flow cytometry meanwhile. The internal calcium ionic concentration in HL-60 cell was detected as well before and after treated with 12G5. The results showed that 12G5 down-regulated the expression of CXCR4 on HL-60 cell membrane; HL-60 cells at G(0)/G(1) phase increased, but decreased at S phase; survive rate of leukemia cells reduced; the intercellular calcium ionic concentration of HL-60 cell decreased after treated with 12G5. It was concluded that brockage of the SDF-1 activity may inhibit proliferation of leukemia cell at certain level.

Antibodies, Monoclonal↗
PubMed2004

[Effects of leukemia bone marrow stromal cells on resistance of co-cultured HL-60 to idarubicin].

To study the role of hematopoietic microenvironment abnormality in development of minimal residual disease and its mechanism, the viability of HL-60 cells was investigated by means of bone marrow stromal cell culture system or co-culture system of bone marrow stromal cell with HL-60 cells and idarubicin (IDA), flow cytometry and ELISA. The results showed that viability of HL-60 cells gradually decreased along with the increase of IDA dose and prolongation of culture time. Amount of HL-60 cells co-cultured with leukemia bone marrow stramal cells was significantly increased as compared with that of the control (P < 0.05). Bone marrow stromal cells or stromal cell conditioned medium reduced the effect of IDA on HL-60 cells in culture. In conclusion, leukemia bone marrow stromal cells contribute to increasing resistance of HL-60 cells to chemotherapeutic agents, and play some role in developing minimal residual disease.

Bone Marrow Cells↗
PubMed2004

Sentinel lymph node identification in patients with early stage cervical cancer undergoing radical hysterectomy and pelvic lymphadenectomy.

BACKGROUND: In general, sentinel lymph node (SLN) can reflect the whole state of the entire drainage area. The present study evaluated the clinical significance of sentinel lymph node identification in the treatment of early stage cervical cancer. METHODS: Twenty-eight patients with early stage (Ia-IIa) cervical cancer undergoing radical hysterectomy and pelvic lymphadenectomy were included in this study. At two locations 8 hours before operation, 0.4 ml 37 Mbq technicium-99 labeled dextran was injected intracervically. After that, preoperative lymphoscintigraphy was performed to detect SLNs. During the operation, lymph nodes were detected ex vivo by a gamma-counter to identify SLNs. The samples of SLNs and non-SLNs were used for pathological examination separately and compared with the final results. RESULTS: SLNs were identified in 27 of 28 (96.4%) patients. A total of 123 SLNs were identified from 814 nodes. Six patients had altogether 11 positive lymph nodes, which were all SLNs. No patient had false-negative sentinel node. CONCLUSION: SLNs can successfully predict the lymphatic metastasis in patients with cervical cancer. The clinical validity of this technique should be evaluated prospectively.

Aged↗
PubMed2004

[Effect of ventilation tube insertion on otitis media with effusion in cleft palate children].

OBJECTIVE: To explore the effect of eardrum tubing in the repair of cleft palate on alleviating the otitis media with effusion (OME) and hearing loss in cleft palate patients. METHODS: Nineteen ears of 19 cleft palate children with OME and hearing loss were treated with the ventilation tube insertion in the repair of the cleft palates, while the untreated opposite ears were selected as the control group. All patients were followed up from 2 weeks to 18 months postoperatively and their middle ear condition and hearing thresholds were reevaluated by otoscopy and pure-tone audiometry. RESULTS: Significant differences were found in the incidences of hearing loss between pre and postoperative patients in treated ears, and there are no differences in the untreated ears. Postoperative hearing thresholds become lower than that before the operation and no serious complications were found in the treated ears. CONCLUSIONS: The ventilation tube insertion in medial ear is safe and effective to restore the hearing impaired by OME in the cleft palate patients. It can be used as a regular management for OME and hearing loss in cleft palate children.

Child↗
PubMed2004

Polyomavirus middle T-induced mammary intraepithelial neoplasia outgrowths: single origin, divergent evolution, and multiple outcomes.

The development of models to investigate the pathobiology of premalignant breast lesions is a critical prerequisite for development of breast cancer prevention and early intervention strategies. Using tissue transplantation techniques, we modified the widely used polyomavirus middle T (PyV-mT) transgenic mouse model of breast cancer to study the premalignant stages of tumorigenesis. Premalignant atypical lesions were isolated from PyV-mT transgenic mice and used to generate two sets of three mammary intraepithelial neoplasia (MIN) outgrowth lines. Investigation of these six unique lines, each of which fulfills the criteria for MIN, has provided new information regarding the biology of PyV-mT-induced neoplasia. Although expression of the PyV-mT transgene was the primary initiating event for all lines, they exhibited different tumor latencies, metastatic potentials, and morphologies. Six distinguishable morphologic patterns of differentiation were identified within the premalignant outgrowths that are likely to represent several tumorigenic pathways. Further, several tumor phenotypes developed from each line and the tumors developing from the six lines had different metastatic potentials. These observations are consistent with the hypothesis that distinct pathways of PyV-mT-initiated neoplastic progression lead to different outcomes with respect to latency and metastasis. The MIN outgrowth lines share several characteristics with precursors of human breast cancer including the observation that gene expression profiles of tumors are more similar to those of the MIN outgrowth line outgrowth from which they developed than to other tumors. These lines provide an opportunity to study the full range of events occurring secondary to PyV-mT expression in the mammary gland.

Animals↗
PubMed2004

[Infection of recombinant adenovirus expressing acidic fibroblasts growth factor enhances rabbit corneal endothelium proliferation].

OBJECTIVE: To transfer the gene encoding mammalian aFGF to rabbit corneal endothelial cell and determine transfection efficiency and the effect of Ad-aFGF on proliferation of RCEC. METHODS: Replication-defective adenovirus was used to deliver the LacZ reporter gene to RCEC to determine transfection efficiency by X-gal staining. A cDNA encoding mammalian aFGF was cloned into an adenoviral vector that was used to transfect RCEC. The expression of aFGF gene mRNA and protein were demonstrated by Reverse transcription PCR and Western blot respectively. The effect of Ad-aFGF on proliferation of RCEC was determined by MTT assay. RESULTS: RT-PCR and Western blot from RCEC infected with Ad-aFGF for 48 h detected a specific cDNA amplification and protein expression of aFGF gene, and no positive result in control cells. Consistently, RCEC infected by MOI 20 of Ad-aFGF demonstrated an enhanced RCEC proliferation compared to controls (F = 217.107, P < 0.05). CONCLUSION: Adenoviral-mediated expression of aFGF can stimulate the proliferation of RCEC.

Adenoviridae↗
PubMed2004

[Effects of anti- CXCR4 monoclonal antibody on adhesiveness of human acute myelocytic leukemia cell line HL-60 and expression of Bcl-2, Fas proteins].

To study the importance of chemokine SDF-1 in surviving of acute myelocytic leukemia cells HL-60, the adhesion ability of HL-60 and expression of Bcl-2, Fas protein when SDF-1 activity was blocked by anti-CXCR4 monoclonal antibody (12G5) were compared with those detected before MAb incubation, in this experiment, HL-60 cell were cultured and co-cultured with normal marrow stromal cell. The adhesion rate was detected while the expression of Bcl-2 and Fas proteins were assayed by immunohistochemical technique when SDF-1 activity was inhibited. The results showed that cell adhesion rate of HL-60 decreased while the expression Bcl-2 decreased and Fas increased. It is concluded that inhibition of SDF-1 activity increases cell apoptosis and thus reduces life-span of leukemia cell at certain level.

Antibodies, Monoclonal↗