Search PubMed⌕ Search

Biomedical subjects

Lin Liu

Publications and source records attributed to Lin Liu.

At least 91 records · Page 5Linked to original sources
PubMed2005

[Expression of aquaporin-4 in isolated and purified rat alveolar type II cells].

OBJECTIVE: To explore the expression of aquaporin-4 (AQP4) in isolated and purified rat alveolar type II cells. METHODS: Rat alveolar type II cells were isolated, purified and identified by special staining and electron microscopy. The distribution of AQP4 in alveolar type II cells was observed by immunocytochemistry and immunoelectron microscope with affinity-purified antibodies to human AQP4. RESULTS: Immunocytochemistry showed staining for AQP4 in rat alveolar type II cells, and immunoelectron microscope demonstrated the presence of AQP4 on the membrane of the cells. CONCLUSION: AQP4 is expressed in alveolar type II cells in rats, and may play a role in water transportation in the respiratory system.

Animals↗
PubMed2005

[Effects of RNA interference inhibiting SDF-1 expression in bone marrow stromal cells on the proliferation and apoptosis of co-cultured Jurkat cells].

OBJECTIVE: To study the effects of RNA interference inhibiting stromal cell derived factor-1 (SDF-1) expression on the proliferation and apoptosis of co-cultured Jurkat cells. METHOD: Inhibition of SDF-1 expression by RNA interference (RNAi) was achieved by transferring SDF-1 specific short hairpin RNA (shRNA) expressing plasmid into cultured human acute leukemic bone marrow stromal cells. Resistant clones were obtained by G418 selection (group A). The concentration of SDF-1 protein in culture supernatant was detected by enzyme-linked immunosorbent assay (ELISA). The population double time (PDT), cell cycles, apoptosis rates and the expressions of PCNA, Bcl-2/Bax, Fas/FasL of co-cultured Jurkat cells were detected by cells counting, flow cytometry. TdT-mediated dUTP nick-end labelling (TUNEL) and immunocytochemistry (ICC), respectively. The un-transfected acute leukemic (group B) and normal (group C) bone marrow stromal cells were taken as controls. RESULTS: The content of SDF-1 protein in supernatant of group A\[(384 +/- 41) pg/ml] was significantly lower than that in group B[(2474 +/- 271) pg/ml] or group C[(1324 +/- 154) pg/ml]. As group A compared with group B and group C, the PDT of co-cultured Jurkat cells was prolonged (group A: 42 h, vs group B: 29 h, group C: 33 h), and G(0)/G(1) stage cells increased [group A: (28.47 +/- 2.39)%, vs group B: (19.43 +/- 2.80)%, group C: (27.15 +/- 2.07)%], S stage cells decreased [group A: (25.57 +/- 1.90)%, vs group B: (74.48 +/- 3.23)%, group C: (60.99 +/- 2.33)%], G(2)/M stage cells increased [group A: (45.96 +/- 3.24)%, vs group B: (6.09 +/- 1.96)%, group C: (11.86 +/- 1.98)%], the apoptosis rate increased [group A: (15.2 +/- 0.8)%, vs group B: (5.4 +/- 0.7)%, group C: (9.5 +/- 0.4)%], and the expressions of PCNA, Bcl-2, Fas decreased; whereas the expressions of Bax and FasL were increased. CONCLUSION: The inhibition of SDF-1 expression in bone marrow stromal cells inhibits the proliferation and promotes the apoptosis of co-cultured Jurkat cells.

Apoptosis↗
PubMed2005

[Surgical management of naso-orbital-ethmoid fractures].

OBJECTIVE: To explore the clinical characteristics of naso-orbital-ethmoid (NOE) fracture, principles and surgical methods. METHODS: Twenty-nine patients with NOE fractures were investigated. Operations for the treatment of NOE and subsequent deformities included reduction of central fragment, reconstruction of orbit walls, reattachment of medial canthal ligament and so on. The outcome of the treatment was evaluated. RESULTS: Three cases were infected postoperatively. Of the 14 cases performed on reconstruction of orbit wall, 9 cases got complete correction for their dystopia/enophthalmos, 5 cases improved. Thirteen cases experiencing canthopexy obtained accepted outcome. CONCLUSIONS: The satisfactory correction of NOE fracture and subsequent enophthalmos/dystopia and telecanthus can be achieved with elective surgery in most cases.

Adolescent↗
PubMed2005

[Effects of inhibiting SDF-1 expression by RNA interference on adhesion and drug sensitivity of Jurkat cells co-cultured with bone marrow stromal cells].

OBJECTIVE: To observe the effects of inhibiting stromal cell derived factor-1 (SDF-1) expression by RNA interference (RNAi) on adhesion and drug sensitivity of Jurkat cells co-cultured with bone marrow stromal cells. METHODS: SDF-1 specific short hairpin RNA (shRNA) expressing plasmid was transferred into cultured human acute leukemic bone marrow stromal cells, positive clones were isolated by screening G418 resistance (Group A) , SDF-1 protein level in culture supernatant was detected by enzyme-linked immunosorbent assay (ELISA). The adhesion rates to bone marrow stromal cells layer and the drug sensitivity to doxorubicin of co-cultured Jurkat cells were detected by cell counting and MTT assay, respectively. The un-transfected bone marrow stromal cells of acute leukemia patient (Group B) or normal subject (Group C) were taken as control. RESULTS: The level of secreted SDF-1 protein (pg/10(5) cells/week) in the supernatants of Group A, B and C were 1920 +/- 205, 12,370 +/- 1355 and 6620 +/- 770, respectively. Of co-cultured Jurkat cells in Group A, B and C, the adhesion rates after 24 h co-culturing were (28.8 +/- 2.6)%, (57.4 +/- 3.8)% and (45.2 +/- 4.0)%, respectively, and the IC50 values of doxorubicin were 585, 6162 and 1758 nmol/L, respectively. CONCLUSION: Down-regulating SDF-1 expression of bone marrow stromal cells by RNAi reduces adhesion rates and enhances drug sensitivity to doxorubicin of their co-cultured Jurkat cells.

Bone Marrow Cells↗
PubMed2005

Cytobiological and clinicobiological features of AML with 11q23 chromosome abnormalities.

To investigate the interrelationship among morphology, immunology and clinical features in adult acute myeloid leukemia cases with 11q23 chromosome abnormalities, 210 newly diagnosed AML patients were retrospectively analyzed by cell morphology, immunophenotyping, G-banding or R-bamding analysis and clinical features. The results showed that 13 cases were found with 11q23 rearrangements or deletion (the incidence rate was 6.19%.), totally 84.6% showed the involvement with the monocytic lineage. Immunophenotyping tests indicated that AML cases with 11q23 abnormalities usually expressed the marker molecules of hematopoietic stem or progenitor cells, monocytic lineage cells, such as CD34, CD117, CD14, CD15 and CD11b. The complete remission rate of the cases with 11q23 abnormalities was comparable to that of the cases with normal karyotype (P = 0.075), but the median disease-free survival in the former was significantly lower than that in the latter (P < 0.001). It is concluded that the category AML with 11q23 abnormalities accounts for 6.19% of all the newly diagnosed AML cases, that seems to be closely associated with monocytic differentiation blocking with a dismal prognosis.

Acute Disease↗
PubMed2005

[Clinicopathologic and radiologic features of dysembryoplastic neuroepithelial tumors].

OBJECTIVE: To study the clinicopathologic features and radiologic findings of dysembryoplastic neuroepithelial tumor (DNT). METHODS: The clinical presentations, radiologic findings, histologic features and immunophenotype of 9 cases of DNT were analyzed. RESULTS: The age of patients ranged from 12 to 51 years (mean age = 32 years). Most presented with partial seizures, sometimes accompanied by transient aphasia, agraphia and decreased visual acuity. One case was asymptomatic and discovered incidentally during a routine check-up. All patients had no neurological deficit found on physical examination. All tumors were located in the supratentorial cerebral cortex. There was no peritumoral edema or space-occupying effect on radiologic examination. The tumors involved either frontal lobe (number = 4), temporal lobe (number = 4), frontoparietal lobe (number = 1) . Two cases showed cystic changes. Two histologic variants of DNT were recognized: simple (number = 3) and complex (number = 6). Simple variant was composed mainly of the glioneuronal element, accompanied by surrounding oligodendrocyte-like cells, and the complex variant contained a low-grade glioma component, in addition to the glioneuronal element and sometimes foci of cortical dysplasia. CONCLUSIONS: DNT is a benign tumor with excellent prognosis after surgical excision. Local recurrence is rare. Complex variant of DNT needs to be distinguished from other types of low-grade glioma.

Adolescent↗
PubMed2004

Role of inducible nitric oxide synthase in N-methyl-d-aspartic acid-induced strio-nigral degeneration.

N-Methyl-d-aspartate (NMDA)-induced striatal excitotoxicity is mediated by nitric oxide (NO) but the role of inflammatory mechanisms and inducible nitric oxide synthase (iNOS) induction is not clear. Unilateral intrastriatal administration of NMDA to rats resulted in the loss of intrinsic striatal neurones and the degeneration of NADPH-diaphorase positive interneurones within 24 h. NMDA administration caused activation of glial fibrillary acidic protein positive astroglial cells and MAC-1 ir microglia. Marked iNOS immunoreactivity was expressed within both astroglial and microglial cells and there was marked cellular labelling for 3-nitrotyrosine (3-NT). One month following the NMDA lesion, administration of (+)-amphetamine (AMPH) produced a circling response in rats. Pre-treatment of rats with the iNOS inhibitor aminoguanidine (AG) decreased the extent of NMDA-induced striatal cell loss at 24 h and reduced 3-NT expression but was without effect on glial cell activation. AG pre-treatment also prevented the onset of rotation to AMPH at 30 days following NMDA lesioning. NMDA administration unexpectedly caused a loss of tyrosine hydroxylase immunoreactive (TH-ir) fibres in the striatum at 24 h and at 30 days the number of TH-ir cells were decreased in the substantia nigra. The loss of nigral cells was prevented by AG pre-treatment. This study demonstrates a role for iNOS induction in NO-mediated NMDA excitotoxicity to rat striatum and suggests that inflammatory mechanisms play a key role in this process.

Animals↗
PubMed2004

Crystal structure of human coactosin-like protein.

Human coactosin-like protein is an actin filament binding protein but does not bind to globular actin. It associates with 5-Lipoxygenase both in vivo and in vitro, playing important roles in modulating the activities of actin and 5-Lipoxygenase. Coactosin counteracts the capping activity of capping protein which inhibits the actin polymerization. We determined the crystal structures of human coactosin-like protein by multi-wavelength anomalous dispersion method. The structure showed a high level of similarity to ADF-H domain, although their amino acid sequences share low degree of homology. A few conserved hydrophobic residues that may contribute to the folding were identified. This structure suggests coactosin-like protein bind to F-actin in a different way from ADF/Cofilin family. Combined with the information from previous mutagenesis studies, the binding sites for F-actin and 5-Lipoxygenase were analyzed, respectively. These two sites are quite close, which might prevent F-actin and 5-Lipoxygenase from binding to coactosin simultaneously.

Actin Depolymerizing Factors↗
PubMed2004

Gene silencing in alveolar type II cells using cell-specific promoter in vitro and in vivo.

RNA interference (RNAi) is a sequence-specific post-transcriptional gene silencing process. Although it is widely used in the loss-of-function studies, none of the current RNAi technologies can achieve cell-specific gene silencing. The lack of cell specificity limits its usage in vivo. Here, we report a cell-specific RNAi system using an alveolar epithelial type II cell-specific promoter--the surfactant protein C (SP-C) promoter. We show that the SP-C-driven small hairpin RNAs specifically depress the expression of the exogenous reporter (enhanced green fluorescent protein) and endogenous genes (lamin A/C and annexin A2) in alveolar type II cells, but not other lung cells, using cell and organ culture in vitro as well as in vivo. The present study provides an efficient strategy in silencing a gene in one type of cell without interfering with other cell systems, and may have a significant impact on RNAi therapy.

Adenoviridae↗
PubMed2004

Cloning, purification, crystallization and preliminary crystallographic analysis of human phosphoglycerate mutase.

Human B-type 2,3-bisphosphoglycerate-dependent phosphoglycerate mutase (dPGM-B) has been cloned, overexpressed and purified, with a yield of 30% of the total protein. Crystals of human dPGM-B were obtained using the hanging-drop vapour-diffusion technique. X-ray diffraction data were collected to 2.8 A resolution. The human dPGM-B crystals belong to space group P2(1), with unit-cell parameters a = 130.5, b = 75.9, c = 187.0 A, beta = 94.4 degrees. There could be between 9 and 18 monomers per asymmetric unit, with 12 molecules being the most likely.

Brain↗
PubMed2004

Expression, purification and preliminary crystallographic studies of human coactosin-like protein.

Coactosin-like protein (CLP) is an actin-binding protein as well as a 5-lipoxygenase binding partner. Human coactosin-like protein has been expressed in high yield and the His-tagged protein was purified by affinity chromatography. Several different crystal forms were obtained by the hanging-drop vapour-diffusion method. X-ray diffraction data to 2.0 A resolution were collected from the best crystal. The space group was determined to be P2(1)2(1)2(1), with unit-cell parameters a = 38.4, b = 48.7, c = 72.6 A.

Brain Chemistry↗
PubMed2004

Nuclear origin of aging-associated meiotic defects in senescence-accelerated mice.

Factors of both cytoplasmic and nuclear origin regulate metaphase chromosome alignment and spindle checkpoint during mitosis. Most aneuploidies associated with maternal aging are believed to derive from nondisjunction and meiotic errors, such as aberrations in spindle formation and chromosome alignment at meiosis I. Senescence-accelerated mice (SAM) exhibit aging-associated meiotic defects, specifically chromosome misalignments at meiosis I and II that resemble those found in human female aging. How maternal aging disrupts meiosis remains largely unexplained. Using germinal vesicle nuclear transfer, we found that aging-associated misalignment of metaphase chromosomes is predominately associated with the nuclear factors in the SAM model. Cytoplasm of young hybrid B6C3F1 mouse oocytes could partly rescue aging-associated meiotic chromosome misalignment, whereas cytoplasm of young SAM was ineffective in preventing the meiotic defects of old SAM oocytes, which is indicative of a deficiency of SAM oocyte cytoplasm. Our results demonstrate that both nuclear and cytoplasmic factors contribute to the meiotic defects of the old SAM oocytes and that the nuclear compartment plays the predominant role in the etiology of aging-related meiotic defects.

Aging, Premature↗
PubMed2004

Crystal structure of human bisphosphoglycerate mutase.

Bisphosphoglycerate mutase is a trifunctional enzyme of which the main function is to synthesize 2,3-bisphosphoglycerate, the allosteric effector of hemoglobin. The gene coding for bisphosphoglycerate mutase from the human cDNA library was cloned and expressed in Escherichia coli. The protein crystals were obtained and diffract to 2.5 A and produced the first crystal structure of bisphosphoglycerate mutase. The model was refined to a crystallographic R-factor of 0.200 and R(free) of 0.266 with excellent stereochemistry. The enzyme remains a dimer in the crystal. The overall structure of the enzyme resembles that of the cofactor-dependent phosphoglycerate mutase except the regions of 13-21, 98-117, 127-151, and the C-terminal tail. The conformational changes in the backbone and the side chains of some residues reveal the structural basis for the different activities between phosphoglycerate mutase and bisphosphoglycerate mutase. The bisphosphoglycerate mutase-specific residue Gly-14 may cause the most important conformational changes, which makes the side chain of Glu-13 orient toward the active site. The positions of Glu-13 and Phe-22 prevent 2,3-bisphosphoglycerate from binding in the way proposed previously. In addition, the side chain of Glu-13 would affect the Glu-89 protonation ability responsible for the low mutase activity. Other structural variations, which could be connected with functional differences, are also discussed.

Amino Acid Sequence↗
PubMed2004

Identification of two novel markers for alveolar epithelial type I and II cells.

Alveolar epithelial type I and type II cells (AEC I and II) are closely aligned in alveolar surface. There is much interest in the precise identification of AEC I and II in order to separate and evaluate functional and other properties of these two cells. This study aims to identify specific AEC I and AEC II cell markers by DNA microarray using the in vitro trans-differentiation of AEC II into AEC I-like cells as a model. Quantitative real-time PCR confirmed five AEC I genes: fibroblast growth factor receptor-activating protein 1, aquaporin 5, purinergic receptor P2X 7 (P2X7), interferon-induced protein, and Bcl2-associated protein, and one AEC II gene: gamma-aminobutyric acid receptor pi subunit (GABRP). Immunostaining on cultured cells and rat lung tissue indicated that GABRP and P2X7 proteins were specifically expressed in AEC II and AEC I, respectively. In situ hybridization of rat lung tissue confirmed the localization of GABRP mRNA in type II cells. P2X7 and GABRP identified in this study could be used as potential AEC I and AEC II markers for studying lung epithelial cell biology and monitoring lung injury.

Animals↗
PubMed2004

Irregular telomeres impair meiotic synapsis and recombination in mice.

Telomere shortening can lead to chromosome instability, replicative senescence, and apoptosis in both somatic and male germ cells. To study roles for mammalian telomeres in homologous pairing and recombination, we characterized effects of telomere shortening on spermatogenesis and oogenesis in late-generation telomerase-deficient mice. We show that shortened telomeres of late-generation telomerase-deficient mice impair meiotic synapsis and decrease recombination, in particular, in females. In response to telomere shortening, male germ cells mostly undergo apoptosis, whereas female germ cells preferentially arrest in early meiosis, suggesting sexually dimorphic surveillance mechanisms for telomere dysfunction during meiosis in mice. Further, meiocytes of late-generation telomerase-deficient females with shortened telomeres, bred with early-generation males harboring relatively long telomeres, exhibit severely impaired chromosome pairing and synapsis and reduced meiotic recombination. These findings imply that functional telomeres are important in mammalian meiotic synapsis and recombination.

Animals↗
PubMed2004

Syntaxin 2 and SNAP-23 are required for regulated surfactant secretion.

The secretion of lung surfactant in alveolar type II cells is a complex process involving the fusion of lamellar bodies with the plasma membrane. This process is somewhat different from the exocytosis of hormones and neurotransmitters. For example, it is a relatively slower process, and lamellar bodies are very large vesicles with a diameter of approximately 1 microm. SNARE proteins are the conserved molecular machinery of exocytosis in the majority of secretory cells. However, their involvement in surfactant secretion has not been reported. Here, we showed that syntaxin 2 and SNAP-23 are expressed in alveolar type II cells. Both proteins are associated with the plasma membrane, and to some degree with lamellar bodies. An antisense oligonucleotide complementary to syntaxin 2 decreased its mRNA and protein levels. The same oligonucleotide also inhibited surfactant secretion, independent of secretagogues. A peptide derived from the N-terminus of syntaxin 2 or the C-terminus of SNAP-23 significantly inhibited Ca(2+)- and GTPgammaS-stimulated surfactant secretion from permeabilized type II cells in a dose-dependent manner. Furthermore, introduction of anti-syntaxin 2 or anti-SNAP-23 antibodies into permeabilized type II cells also inhibited surfactant release. Our results suggest that syntaxin 2 and SNAP-23 are required for regulated surfactant secretion.

Amino Acid Sequence↗