PubMed Health⌕ Search

Biomedical subjects

Yan Liu

Publications and source records attributed to Yan Liu.

At least 361 records · Page 20Linked to original sources

[Effects of hexamethylene bisacetamide on cell cycle and expression of its regulatory proteins in HL-60 cells].

Hexamethylene bisacetamide (HMBA) is referred as a differentiation-inducer for the clinical treatment of acute myeloid leukemia and myelodysplastic syndrome. However, the molecular mechanism of the effects of HMBA on myeloid leukemic cells remains unknown. In this study, the effects of HMBA on cell cycle and expression of cell cycle regulatory proteins in HL-60 cell were investigated in order to explore its pharmacological mechanism. The altered distribution of cell cycle and expression of its regulatory proteins (cyclin D, cyclin E and p27) in HL-6 0 cell induced by HMBA were analyzed by flow cytometry. The effects on transcription for mRNA of CKI p15, p16 and p27 in HL-60 cell were further studied by RT-PCR. The results showed that HMBA could mainly commit HL-60 cell to G0/G1 arrest and the significantly decreased endocytic cyclin E protein and increased cyclin D/p27 protein after HMBA treatment were found. There was no expression of p15, p16 mRNA in untreated HL-60 cell and 3 mmol/L of HMBA could make them expressed after exposed for 24 h or 48 h respectively. The expression of p27 mRNA was positive and no obviously different in untreated HL-60 cells exposed for 24 h, 48 h and 72 h. These results suggested that one of the pharmacological mechanisms of HMBA was to elevate the expression of p27 and reduce the cyclin E expression as well as to activate the expression of p15, p16 gene mRNA, that arrested cell at G0/G1 and exerted its effects of anti-proliferation.

Acetamides↗

[Studies of TGF-beta/Smads expression in lung cancer].

Smad proteins transduce signals from transforming growth factor beta superfamily ligands that regulate cell proliferation, differentiation and death through activation of receptor serine/threonine kinases. TGF-beta/Smads signal pathway not only has transforming potential but can also drive tumourigenesis, malignant progression, invasion and metastasis of human cancers. Using the immuno-histochemistry, we investigate the expression and location of TGF-beta R II, Smad2, Smad4 and Smad7 in 20 lung cancer specimens and 8 lung cancer cell lines. The results suggest that aberrant smads protein expression is significantly related to lung cancer tumoruigenesis and progression. Interestingly, TGF-beta R II and Smad7 strongly express in high metastasis cell lines. High expression of TGF-beta R II and smad7 in the cell lines with high-metastatic potential showed a conceivable TGF-beta signal pathway independent Smads in the lung cancer, and that might mediate invasion and metastasis of lung cancer.

DNA-Binding Proteins↗

Screening of augmenter of liver regeneration-binding proteins by yeast-two hybrid technique.

OBJECTIVE: To investigate the biological function of augmenter of liver regeneration (ALR), we used yeast-two hybrid technique to detect proteins in hepatocytes interacting with ALR. METHODS: ALR bait plasmid was constructed by using yeast-two hybrid system 3, then transformed into yeast AH109. The transformed yeast was mated with yeast Y187 containing liver cDNA library plasmid in a 2XYPDA medium. Diploid yeast was plated on a synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing x-alpha-gal for selection and screening. After extracting and sequencing of the plasmid from blue colonies. Analysis was performed by bioinformatics. RESULTS: Of 36 colonies sequenced, 14 are metallothionein, 12 albumin, and 3 selenoprotein P. One colony is a new gene with unknown function. CONCLUSION: The successful cloning of gene of ALR interacting protein has paved the way for studying the physiological function of ALR and associated proteins.

Animals↗

Single nucleotide polymorphisms in promoter of angiotensin II type 1 receptor gene associated with essential hypertension and coronary heart disease in Chinese population.

AIM: To discover single nucleotide polymorphisms (SNPs) in the promoter region of angiotensin II type 1 receptor (AT1) gene and evaluate their associations with the occurrence of essential hypertension (EH) and coronary heart disease (CHD) in Chinese Han population. METHODS: SNPs detection was performed by PCR-sequencing. The genotype was determined by the same method in a total number of 473 unrelated patients including 160 EH cases, 128 CHD cases, and 185 EH combined with CHD cases as well as 160 healthy controls. RESULTS: Six SNPs were discovered in the promoter region of AT1 gene. -810A/T was almost in completely linkage disequilibrium with -713G/T, -214A/C, -213G/C, and -153A/G polymorphisms. No statistically association was found in our population between -810A/T polymorphism and EH, the association of -810A allele and CHD was of borderline significant (chi2=3.649, P=0.056). However, significant differences of genotype distributions were observed in the EH combined with CHD group (TT=126, TA=51, AA=8) compared with the EH patients (TT=127,TA=26, AA=7, chi2=6.410, P=0.041) and the healthy controls (TT=130, TA=24, AA=6, chi2=7.742, P=0.021). The EH combined with CHD patients had a significantly increased A allele frequency than the normal references (0.181 vs 0.106, chi2=7.690, P=0.006) and the EH subjects (0.181 vs 0.125, chi2=4.119, P=0.042). Hypertensive patients carrying TA genotype (OR=1.977, 95 % CI 1.160-3.354, P=0.011) or A allele (OR=1.548, 95 % CI 1.015-2.361, P=0.043) had an increased risk for CHD morbidity. CONCLUSION: we firstly report that -810A/T polymorphism in the promoter region of AT1 gene might be a genetic risk factor for the pathogenesis of CHD complicated with EH in Chinese Han population.

Aged↗

[Stability of teeth alignment after orthodontic treatment].

OBJECTIVE: To investigate the relapse of incisor alignment after orthodontic treatment and possible factors which may related to its stability. METHODS: 72 finished cases with full records selected from orthodontic clinic of Peking University School of Stomatology composed the sample. The follow-up lateral head films and study casts were taken at least 2 years after orthodontic treatment. The cephalograms were measured by computerized program and the study casts measured by caliper. RESULTS: The upper Irregularity Index decreased from (11.5 +/- 5.02) mm before treatment to (2.01 +/- 1.39) mm after treatment and then increased to (3.46 +/- 1.69) mm in the follow-up stage. The lower Irregularity Index decreased from (7.24 +/- 44.35) mm before treatment to (1.75 +/- 1.04) mm after treatment and then increased to (3.39 +/- 1.78) mm in the follow-up stage. The changes are significant statistically. The changes of jaw in the sagittal and vertical directions as well as the related changes of the position of lower incisors, the decrease of the lower canine arch width, Bolton Index and sex all have statistically significant relation with the changes of the lower Irregularity Index after retention. CONCLUSIONS: Compared with lower arch, the alignment in upper arch is more stable in the follow-up stage. The results suggest that some possible factors may have correlations with the change of lower arch crowding during the follow-up stage.

Adolescent↗

[Effect of hepatic artery embolization on the microwave coagulated area].

OBJECTIVE: To study the effect of hepatic artery embolization on the microwave coagulated area, an in vivo animal experiment. METHODS: Twenty-four suitable hepatic lobes of ten dogs were divided into two groups: microwave coagulation alone 12 lobes (control group) and hepatic artery occlusion with iodized oil and gelatin sponge particles followed by microwave coagulation 12 (experiment group). Microwave coagulation was delivered with an output of 50 W for 300 or 400 seconds with thermal needles introduced parallel to and 5 approximately 20 mm from the puncture needle. After sacrifice of the dogs, their hepatic lobes were sectioned along the puncture line. Then, the appearance and size of the coagulated area were recorded. The tissue specimens were fixed in formalin for light microscopic evaluation. RESULTS: A decline in temperature gradient was detected from the center to the periphery of the affected tissue after the application of microwave coagulation, which was sharper in the control group than in the experimental group. Single polar microwave coagulation at 50 W for 300 seconds produced a necrotic volume of 25 approximately 33 mm in longitudinal diameter and 13 approximately 22 mm in transverse diameter in control group, 33 approximately 44 mm and 24 approximately 32 mm in the experimental group. The coagulation area was slightly bigger when the duration of coagulation was 400 seconds than 300 seconds, without significant difference. CONCLUSION: Hepatic artery occlusion, inhibiting the heat loss caused by hepatic arterial blood flow, is able to significantly enlarge the necrotic volume of microwave coagulation.

Animals↗

A prospective study of cruciferous vegetables and prostate cancer.

High intake of cruciferous vegetables may offer some protection against prostate cancer, but overall data are inconclusive. Thus, we examined the association between cruciferous vegetable intake and risk of prostate cancer in the Health Professionals Follow-Up Study. Between 1986 and 2000, 2,969 cases of nonstage T1a prostate cancer were diagnosed in 47,365 men who completed dietary assessments in 1986, 1990, and 1994. We calculated the multivariate relative risk (RR) and 95% confidence intervals (CIs) using Cox regression. Overall, we found no appreciable association between baseline intake of cruciferous vegetables and risk of prostate cancer (RR, 0.93; 95% CI, 0.82-1.05, for > or = 5 versus < or = 1 serving/week; P for trend = 0.30), and only a slight suggestive association for organ-confined prostate cancer (RR, 0.88; 95% CI, 0.74-1.05; P for trend = 0.06). The inverse association was stronger for men under the age of 65 years (RR, 0.81; 95% CI, 0.64-1.02; P for trend = 0.02), especially for organ-confined cancers (RR, 0.72; 95% CI, 0.54-0.97; P for trend = 0.007). In addition, this inverse association was stronger when we restricted the analysis to men with more consistent intake of vegetables over the 10 years before 1986, when we limited the analysis to men who had had a prostate-specific antigen test, and when we considered an 8-year time lag. This study does not provide compelling evidence of a protective influence of cruciferous vegetables on prostate cancer risk. However, if cruciferous vegetables are protective early in prostate carcinogenesis, as suggested by proposed mechanisms, we may expect stronger associations, as observed, for more remote diet for prostate-specific antigen-detected early stage (organ-confined) cancers in younger men. In contrast, for advanced cancers in older men, which were probably initiated decades in the past, recent dietary intakes of cruciferous vegetables may be irrelevant. These findings suggest that future studies of cruciferous vegetables should focus on early stages of prostate cancer.

Adult↗

[Construction of subtracted cDNA library in human Jurkat T cell line induced by arsenic trioxide in vitro].

OBJECTIVE: To understand the differentially expressed genes in human T lymphocytes induced by arsenic trioxide (As(2)O(3)) and to explore mechanism of its immunotoxicity and immune suppression. METHODS: Human Jurkat T cell line was treated by arsenic trioxide (5 micromol/L, 24 h) in vitro, as a sample model. Then, the differentially expressed genes were cloned and the subtractive cDNA library from Jurkat T cell line was constructed by suppression subtractive hybridization (SSH). Polymerase chain reaction (PCR) and sequencing techniques were applied to identify positive clones. RESULTS: The forward subtracted cDNA library contained differentially expressed genes from Jurkat T cell line induced by arsenic trioxide was constructed, including 29 different gene fragments and only replicated one in the subtracted cDNA library identified by PCR and sequencing analysis. These gene sequences were 95%-100% analogous to the genes in public database (GenBank/EMBL). The cDNA library contained oxidative metabolic genes in mitochondria (triose phosphate dehydrogenase, NADH4, pyrophosphate synthase, 16S rRNA ribosome, succinate-CoA ligase and ATP synthase 6); transcriptional and translation genes poly (A) binding protein, t-RNA-guanine transglycoslase, ribosomal protein L23, ribosomal protein S15A, eukaryotic translation initiation factor 3, Rab interaction protein 5, splicing factor-arginine serine rich 5, and ADP-ribosylation factor-like 6 interacting protein), oxide stress related genes (ferritin high chain and high-mobility group protein 2); protein activating and signaling pathway related genes (casein kinase, serine kinase 2 and phosphatidylinositol-four-phosphate adaptor protein-1-associated protein); cell differentiation and apoptosis associated genes (NB4 cell apoptosis related protein and myeloid differentiation primary response protein) and five genes with unknown function (KIAA0092, CGI-147protein, GCI-35, nucleolar phosphoprotein Nopp34 and Mus muscular partial mRNA for hypothetical protein), as well as a novel gene unmatched to the sequence in GenBank. CONCLUSIONS: The forward subtracted cDNA library contained differentially expressed genes from Jurkat T cell line induced by arsenic trioxide was successfully constructed. And, genes not involved in previous research on arsenic were found. Results of analysis for these genetic function suggested that there should be many genes involved in process of T lymphocytes apoptosis or injury induced by arsenic trioxide and that there should still be many genes associated with arsenic that were not reported in the past.

Antineoplastic Agents↗

[In vitro experimental study of gene therapy for ovarian cancer with thymidine kinase gene of herpes simplex virus mediated by a non-viral GE7 delivery system].

OBJECTIVE: To investigate gene transfer efficiency of a novel target non-viral vector GE7 and effects of herpes simplex virus thymidine kinase (HSV(1)-tk)/ganciclovir (GCV) mediated by it in vitro. METHODS: The epidermal growth factor receptor (EGF-R) target gene delivery system GE7 was constructed. Human ovarian cancer cell line CAOV3 was transfected in vitro with beta-galactosidase (beta-gal) as reporter gene and HSV(1)-tk gene as therapeutic gene using this gene delivery system. By means of the assay of X-gal staining, Northern blotting, cell growth-inhibiting curve and so on, the transferring efficiency of exogenous genes and killing effects are observed. RESULTS: It showed that gene transfer efficiency is over 80%. When 10 mg/L GCV was put into ovarian cells transfected with HSV(1)-tk gene, 95% of cells were killed, and the apoptosis ratio reached up to 30. CONCLUSIONS: The GE7 gene delivery system is an effective and safe delivery system. GE7/HSV(1)-tk/GCV therapeutic gene system is appraising for ovarian cancer.

Cell Division↗

[Methylprednisolone and cyclophosphamide pulse therapy of severe systemic lupus erythematosus in children].

OBJECTIVE: To study the effect of methylprednisolone (MP) and cyclophosphamide (CPA) intermittent intravenous pulse therapy and the clinical prognosis in children with severe juvenile onset systemic lupus erythematosus (JOSLE). METHODS: Thirty patients with JOSLE, diagnosed by clinical, laboratory or renal histological examinations, were enrolled in this study. Of the 30 patients, 27 were females and 3 were males, the mean age was (12 +/- 3) years, and 20 of the 22 patients who had undergone initial therapy had LN, and the clinical courses before being involved in the study were 3 to 12 months in nine patients. Twenty-three of the 30 patients had clinical manifestations of renal damages, of whom 4 patients were proven by initial renal biopsy to have WHO type IV, 2 had type II,1 had type V and 1 had type III, and 7 patients had one or more manifestations of central nervous system, including chorea, seizures, cerebrovascular accident (CVA) and organic brain syndrome (OBS), simultaneously, 9 patients had nervous system symptoms without the clinical manifestations of renal damages, 3 patients had lupus crisis, 7 patients did not have any manifestations of renal or neurological damages. According to the protocol of the therapy, the patients were divided into 3 groups: group A (n = 18) patients were treated with MP plus CPA intermittent intravenous pulse for children with lupus nephritis, and with or without neuropsychiatric lupus erythematosus (NPLE), group B (n = 7) with pulsed doses of MP, followed by prednisone and tripterygium wilfordii hook f(T(whf)) for patients without renal or central nerves system damage, and group C (n = 5) with prednisone alone for patients with LN determined by clinical and laboratory features. The effects of those regimes and the clinical prognosis were observed. RESULTS: On short-term follow-up, the SLEDAI-2K (by weight of the renal damage) showed significant difference between group A and group B, but there was no significant difference at the 9th months of the therapy. The long-term follow-up lasted in average for (37.2 +/- 24.8) months. Nineteen patients were followed up for more than 18 months. At the end of follow-up, the mean age was 14 to 19 years. There was no difference on the effect of both group A and group B, and no frequent infections were seen, ANAs were negative and SLEDAI-2K = 0-point in two patients of each group 12 months after discontinuation of the therapy. Four patients in group C died within 18 months. CONCLUSION: The immunosuppressive regimen MP + CPA in patients with severe JOSLE and MP + prednisone + T(whf) in patients without major organs damage were superior to the regimen of prednisone alone.

Adolescent↗

[The effect of treating obstructive disease of lacrimal passage by lacrimal plastic operation with Nd:YAG laser].

OBJECTIVE: To study the therapeutic effects of Nd:YAG laser on obstructive diseases of the lacrimal passage. METHODS: 693 eyes in 603 cases with obstructive diseases of lacrimal passage, including obstruction of lacrimal puncta (23 eyes), lacrimal duct (192 eyes), nasolacrimal duct (227 eyes), chronic dacryocystitis (231 eyes), and traumatic laceration of lacrimal canaliculus (20 eyes), were treated by lacrimal plastic operation with Nd:YAG laser and the therapeutic effects were compared among the groups. RESULTS: The cure rates and effective rates of the five diseases were 86.9% and 95.7%, 89.1% and 93.8%, 93.0% and 96.0%, 78.4% and 82.7%, 40.0% and 65.0%, respectively. By Ridit analysis, R +/- S(R) values for each group were 0.921 +/- 0.023, 0.914 +/- 0.009, 0.927 +/- 0.007, 0.856 +/- 0.013, 0.749 +/- 0.055. CONCLUSIONS: The therapeutic effect on chronic dacryocystitis is less than those of obstruction of nasolacrimal duct and lacrimal duct (P < 0.05). The therapeutic effect on traumatic laceration of lacrimal canaliculus is less than that of the other four groups (P < 0.05). Therefore, it should be restricted on indication for the cases of chronic dacryocystitis and traumatic laceration of lacrimal canaliculus.

Adolescent↗

Galacto, gluco, manno, and disaccharide-based C-glycosides of 2-amino-2-deoxy sugars.

[reaction: see text] Starting from readily available precursors, selenoglycosides derived from GalNAc, GlcNAc, and ManNAc were prepared by either a one- or a two-step process. The anomeric selenides underwent facile C-Se homolysis to provide the corresponding anomeric radicals, which were trapped with alkenes to give C-glycosides. This provides a general entry to alpha-C-glycosides based on 2-amino-2-deoxy sugars that is also applicable to disaccharide variants.

Amino Sugars↗

Pulmonary complications in survivors of childhood and adolescent cancer. A report from the Childhood Cancer Survivor Study.

BACKGROUND: The Childhood Cancer Survivor Study is a resource that was designed to investigate long-term effects among 5-year survivors of childhood and adolescent malignancies. Previous studies have shown that exposure to chemotherapy and/or radiation can compromise pulmonary function in these survivors of childhood cancer. METHODS: Using information obtained from questionnaires from 12,390 childhood cancer survivors and 3546 randomly selected siblings, the authors evaluated the rate of first occurrence of 15 selected pulmonary conditions in three periods: during therapy, from the end of therapy to 5 years postdiagnosis, and >/= 5 years postdiagnosis. Multivariate analyses were used to determine the relative risks with 95% confidence intervals of reported pulmonary conditions by exposure to the following treatment variables: radiation therapy to the chest, bleomycin, cyclophosphamide, busulfan, lomustine (CCNU), and/or carmustine (BCNU). RESULTS: Compared with siblings, survivors had a statistically significant increased relative risk (RR) of lung fibrosis, recurrent pneumonia, chronic cough, pleurisy, use of supplemental oxygen, abnormal chest wall, exercise-induced shortness of breath, bronchitis, recurrent sinus infection, and tonsillitis for all three periods. During the period of >or= 5 years postdiagnosis, statistically significant associations were present for lung fibrosis and chest radiation (RR, 4.3; P = 0 001); for supplemental oxygen use and chest radiation (RR, 1.8; P < 0.001), BCNU (RR, 1.4; P = 0.05), bleomycin (RR, 1.7; P = 0.001), busulfan (RR, 3.2; P = 0.002), CCNU (RR, 2.1; P < 0.001), and cyclophosphamide (RR, 1.5; P = 0.01); for recurrent pneumonia and chest radiation (RR, 2.2; P = 0.001) and cyclophosphamide (RR, 1.6; P = 0.04); for chronic cough and chest radiation (RR, 2.0; P < 0.001), bleomycin (RR, 1.9; P < 0.001), and cyclophosphamide (RR, 1.3; P = 0.004); and for pleurisy and chest radiation (RR, 1.4; P = 0.02) and busulfan (RR, 5.1; P = 0.02). Chest radiation was associated with a 3.5% cumulative incidence of lung fibrosis at 20 years after diagnosis. CONCLUSIONS: For self-report of pulmonary conditions, treatment-related factors that continue to manifest > 5 years after diagnosis and treatment are important determinants of risk. Continued follow-up of childhood cancer survivors is needed to evaluate the impact of pulmonary conditions on quality of life.

Adolescent↗

Enhanced activation of mitogen-activated protein kinase and myosin light chain kinase by the Pro33 polymorphism of integrin beta 3.

Integrin beta(3) is polymorphic at residue 33 (Leu(33) or Pro(33)), and the Pro(33) variant exhibits increased outside-in signaling to focal adhesion kinase and greater actin reorganization. Because focal adhesion kinase activation and an intact cytoskeleton are critical links for integrin-mediated signaling to MAPK, we explored the role of integrin alpha(IIb)beta(3) in this signaling using Chinese hamster ovary and human kidney 293 cell lines expressing either the Leu(33) or Pro(33) isoform of beta(3). Compared with Leu(33) cells, Pro(33) cells demonstrated substantially greater activation of ERK2 (but not MAPK family members JNK and p38) upon adhesion to immobilized fibrinogen (but not fibronectin) and upon integrin cross-linking. ERK2 activation was mediated through MAPK kinase and required phosphoinositide 3-kinase signaling and an intact actin cytoskeleton. Human platelets and Chinese hamster ovary cells expressing the Pro(33) isoform showed enhanced activation of the ERK2 substrate myosin light chain kinase (MLCK) upon adhering to fibrinogen. Furthermore, compared with platelets and cells expressing the Leu(33) isoform, the Pro(33) variant showed greater alpha-granule release, clot retraction, and adhesion to fibrinogen under shear stress, and these functional differences were abolished by MLCK and MAPK kinase inhibition. Post-integrin occupancy signaling through MAPK and MLCK after alpha(IIb)beta(3) cross-linking may explain in part the increased adhesive properties of the Pro(33) variant of integrin beta(3).

Animals↗

Analysis of oligoguluronic acids with NMR, electrospray ionization-mass spectrometry and high-performance anion-exchange chromatography.

Oligoguluronates were prepared by enzymatic hydrolysis of homopolymeric blocks of guluronic acids. Two different oligosaccharides were prepared by separating final hydrolysates on Q-Sepharose FF ion chromatography. High-performance anion-exchange chromatography analysis showed the high purity of these oligosaccharides. The molecular masses of these two oligosaccharides, determined by electrospray ionization-mass spectrometry, were 396 and 594, respectively. 1H, 13C NMR, H-H COSY and HSQC analysis proved that they were the unsaturated dimer and trimer oligoguluronates. The 1H and 13C NMR chemical shifts of these two oligosaccharides are also reported.

Anion Exchange Resins↗

Modulation of the human polycystin-L channel by voltage and divalent cations.

Polycystin-L (PCL) is highly homologous in sequence and membrane topology to polycystin-2, the product of the second gene responsible for autosomal dominant polycystic kidney disease (ADPKD). PCL and polycystin-2 were recently shown to be Ca2+-permeable, Ca2+-activated cation channels. Further characterization of polycystins will help in the understanding of cystogenesis and pathogenesis of ADPKD. In the present study, we expressed human PCL in Xenopus oocytes and studied its function utilizing patch-clamp and two-electrode voltage clamp techniques. In addition to its permeability to Ca2+, K+ and Na+, PCL was highly permeable to NH4+ and Cs+ with a permeability ratio NH4+:Cs+:Na+ of 2.2:1.02:1. Voltage modulation of channel properties was studied using cell-attached (C-A) and excised inside-out (I-O) patches. In the C-A mode, the open probability (NP(o)) of PCL at negative potentials (NP(o)=0.22) was higher than at positive potentials (NP(o)=0.05). The mean open time averaged 31.6 ms at negative potentials, and 6.2 ms at positive potentials; single-channel activity exhibited bursts with a mean interburst time of 178 ms. Using I-O patches under symmetrical ionic conditions, single-channel inward conductance was significantly larger than outward conductance, indicating a slight inward rectification. External Mg2+ inhibited the PCL channel currents. The inhibitory effect was voltage-dependent and substantially reduced by depolarization. The time course of inactivation depended on external calcium concentration but was independent of voltage and peak current. This study shows that although PCL is not a voltage-gated channel, its channel activity and inhibition by Mg2+ are modulated by membrane potential.

Animals↗