Biomedical subjects

M Liu

Publications and source records attributed to M Liu.

At least 397 records · Page 22Linked to original sources

PubMed1998

Regulation of the human proliferating cell nuclear antigen promoter by the adenovirus E1A-associated protein p107.

The adenovirus E1A 243R oncoprotein is capable of transactivating the expression of the human proliferating cell nuclear antigen (PCNA) promoter. Mutational analysis of the E1A 243R protein suggested that both its p300/CBP- and p107-binding regions are required for optimal induction of the PCNA promoter (C. Kannabiran, G. F. Morris, C. Labrie, and M. B. Mathews, J. Virol. 67:425-437, 1993). We show that overexpression of p107 antagonizes the induction of PCNA by E1A 243R in transient expression assays. This inhibition is largely independent of p107's ability to interact with E1A 243R, because p107 mutants unable to bind to E1A 243R retain the ability to repress the E1A-activated PCNA promoter. Electrophoretic mobility shift assays with the PCNA promoter detected the presence of p107 in one of the major DNA-protein complexes, EH1, formed with HeLa cell nuclear extracts. Promoter mutations that disrupt the formation of complex EH1 abrogated p107's ability to reverse E1A 243R-induced PCNA expression. The same mutations characterize a sequence important for the binding of transcription factor RFX1 (C. Labrie, G. F. Morris, and M. B. Mathews, Nucleic Acids Res. 23:3732-3741, 1995), implying that p107 antagonizes E1A 243R-induced PCNA expression through this RFX1-binding site. Our data are suggestive of a novel cooperative mechanism for transactivation of PCNA expression, in which E1A 243R relieves transcriptional repression exerted by p107 on the promoter.

Adenoviridae↗

PubMed1998

A differential screen for ligand-regulated genes: identification of HoxA10 as a target of vitamin D3 induction in myeloid leukemic cells.

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the hormonal ligand for vitamin D3, is a potent inducer of myeloid-leukemic-cell differentiation. Such cells differentiate exclusively into monocytes/macrophages in response to this ligand. Since 1,25(OH)2D3 transduces its hormone signal through the vitamin D3 receptor (VDR), a ligand-modulated transcription factor and member of the nuclear hormone receptor superfamily, we sought to identify direct VDR target genes induced during this differentiation process. To do so, we applied a modified differential screen with a nascent-RNA purification strategy using biases for immediate-early-response genes induced by 1,25(OH)2D3 in the myelomonocytic cell line U937. Using this screen, we had previously identified p21Waf1/Cip1 as a gene transcriptionally induced by 1,25(OH)2D3 and demonstrated that this induction facilitates the differentiation of U937 cells into monocytes/macrophages (24). Here, we describe in detail our differential screen strategy and the identification and isolation of 20 1,25(OH)2D3-inducible genes or unknown cDNAs by means of this screen. One gene newly identified as a target of VDR regulation in myeloid cells is the homeobox HoxA10 gene. HoxA10 protein may act as a general regulator of cell growth, since overexpression of HoxA10 facilitated the differentiation of U937 cells into monocytes/macrophages independent of 1,25(OH)2D3 and acted to strongly inhibit the growth of the breast cancer cell line MCF-7 by arresting these cells in G1.

Breast Neoplasms↗

PubMed1998

PDGF-induced glycosaminoglycan synthesis is mediated via phosphatidylinositol 3-kinase.

Platelet-derived growth factor (PDGF)-BB has been shown previously to increase glycosaminoglycan (GAG) synthesis but not DNA synthesis in freshly isolated fetal lung fibroblasts. In the present study, we found that PDGF-BB also enhanced 35SO4 incorporation into the small, soluble proteoglycan biglycan without affecting biglycan's core protein mRNA expression, suggesting that PDGF-BB mainly affects GAG chain elongation and/or sulfation. PDGF-BB-stimulated GAG synthesis was abrogated by tyrphostin 9, a PDGF receptor-associated tyrosine kinase inhibitor, implying that the stimulatory effect is mediated via the PDGF beta-receptor (PDGFR). The intracellular signal transduction pathways that mediate PDGF-BB-stimulated GAG synthesis in fetal lung fibroblasts were investigated. On ligand-induced tyrosine phosphorylation, PDGFR associated with phospholipase C (PLC)-gamma 1, Ras GTPase activating protein (RasGAP), and phosphatidylinositol 3-kinase (PI3K) but not with the Syp-growth factor receptor-bound protein 2-Son of Sevenless complex. Association of PDGFR with PLC-gamma 1 and RasGAP followed by their tyrosine phosphorylation failed, however, to activate PLC-gamma 1, protein kinase C (PKC), and Ras. Neither a PLC-gamma inhibitor, U-73122; a PKC inhibitor, calphostin C; nor a mitogen-activated protein kinase kinase inhibitor, PD-98059, inhibited PDGF-BB-induced GAG synthesis. In contrast, PDGF-BB stimulation triggered PDGFR-associated PI3K activity. Both PDGF-BB-induced PI3K activation and GAG synthesis were abolished by the PI3K inhibitors wortmannin and LY-294002. The results suggest that PI3K is a downstream mediator of PDGF-BB-stimulated GAG synthesis in fetal rat lung fibroblasts.

Animals↗

PubMed1998

Mesenchymal determination of mechanical strain-induced fetal lung cell proliferation.

Fetal breathing movements play an important role in normal fetal lung growth. We have previously shown that an intermittent mechanical strain regimen (60 cycles/min, 15 min/h), simulating normal fetal breathing movements, stimulated growth of mixed fetal rat lung cells in organotypic culture. In the present study, we examined the individual responses of the two major fetal lung cell types, fibroblasts and epithelial cells, to mechanical strain. Also, we investigated the effect of mesenchymal-epithelial interactions on strain-induced cell proliferation during fetal lung development. Fibroblasts and epithelial cells from day 18 to day 21 fetal rat lung (term = 22 days), cultured alone or as various recombinants, were subjected to either a 48-h static culture or to strain, and DNA synthesis was measured. Both cell types responded individually to strain with enhanced DNA synthesis throughout late fetal lung development. Independent of the recombination ratio, there was no additive response to strain when fibroblasts and epithelial cells from the same gestation were recombined. In contrast, strain-induced DNA synthesis was suppressed when cells from different gestations were recombined. The ontogenic response pattern of recombinants to mechanical strain was similar to that of fibroblasts but not of epithelial cells. Strain-induced proliferation increased and peaked at the early canalicular stage of lung development at 19 days of gestation and declined thereafter. We conclude that strain-enhanced growth of the fetal lung is gestation dependent and that the gestational response to mechanical force is regulated by the mesenchyme.

Animals↗

PubMed1998

Influence of mechanical stretch on thrombin regulation by fetal mixed lung cells.

Respiratory distress syndrome (RDS) is characterized by intrapulmonary fibrin deposition, which can adversely affect surfactant function, and stimulate fibroblast proliferation, which may contribute to the development of bronchopulmonary dysplasia (BPD). We speculated that the premature lung may have impaired regulation of thrombin, thus making preterm infants susceptible to fibrin formation within the lung. Therefore, we studied the effect of stretch, which simulates fetal breathing movements (FBMs), on the generation and inhibition of a key hemostatic enzyme-thrombin-by rat fetal mixed lung cells (FMLCs). Our results showed that stretch induced glycosaminoglycan production with increased antithrombin activity due to an increase in the concentration of active chondroitin sulfate. Stretch downregulated secretion of tissue factor procoagulant activity, which may lead to decreased thrombin generation on the surface of FMLCs. Overall, stretch enhanced the local control of thrombin by FMLCs. These results suggest that premature infants, who will have experienced less FBM, may have impaired thrombin regulation. Impaired thrombin regulation likely contributes to increased fibrin deposition and, potentially, the development of BPD.

Animals↗

PubMed1998

Developmental alterations of alpha-fetoprotein sugar chain in amniotic fluids analyzed by lectin affinity electrophoresis.

Affinity electrophoresis of human alpha-fetoprotein (AFP) in amniotic fluid from pregnant women between 6 to 42 weeks of gestation and in the serum of a yolk sac tumor was performed with concanavalin A (Con A), lentil lectin (LCA), erythroagglutinating phytohemagglutinin (E-PHA) and Allomyrina dichotoma lectin (allo A). Separated AFP bands were detected by sensitive antibody-affinity blotting. In the first trimester, amniotic fluid AFP showed elevated percentages of Con A-nonreacting AFP (AFP-C1) and LCA weakly-reacting AFP (AFP-L2) as previously reported. Additionally, high percentages of E-PHA strongly-reacting AFP (AFP-P5) and E-PHA-reacting AFP (AFP-P4) were observed. E-PHA-nonreacting AFP (AFP-P1), E-PHA weakly-reacting AFP (AFP-P3f), allo A-nonreacting AFP (AFP-A1) and asialo-AFP, AFP-A1 s, were present only in amniotic fluids from 6 to 17 weeks of gestation. With advancing gestation, percentages of AFP-C1, AFP-P4 and AFP-P5 decreased and AFP-L2, AFP-P3f, AFP-A1, and AFP-A1 s disappeared by the end of 18 weeks. The glycoforms of serum AFP of the yolk sac tumor resembled those of amniotic fluid AFP in the early gestational stages.

Amniotic Fluid↗

PubMed1998

[Long-term result of free forearm skin flap for repair of soft tissue defects of the oral and maxillofacial regions].

To evaluate the long-term result of free forearm skin flap in the repair of soft tissue defects of the oral and maxillofacial regions, 26 cases which had received radical resection of maxillofacial tumors were follow-up for 4.5 years. Twenty cases, having complete data were analyzed. In this series, There were 8 males and 12 females, with ages ranged from 40 to 69 years old. The size of the flaps ranged from 4 cm x 5 cm-6 cm x 13 cm. The radial artery and the cephalic vein were used as the donor vessels, and the maxillary artery, superior thyroid artery, external jugular vein and the anterior jugular vein were prepared as the recipient vessels. According to the shape, colour, temperature, sensation, mucosoid degree of the flap, the blood supply and function of hand and the configuration of the forearm, the overall results of the recepient regions in 20 cases were all satisfactory and the overall results of 16 cases donor regions were satifactory in 16 cases. The results were poor in 4 cases. The conclusion were: 1. Free forearm skin flap was worth trying in the repair of soft tissue defects of oral region; 2. The radial artery need not to be reconstructed because of the abandant vascular net-work in the upper limb and 3. The residual scar on the forearm was the main shortcoming, but most of the patients could tolerate it because of the obvious advantages received from the operation.

Adult↗

PubMed1998

[The experimental study of the effect of insulin and danshen on culture of fibroblast in vitro].

UNLABELLED: To investigate the effect of Insulin and Danshen on anabolism and catabolism of collagen during the healing of wound, fibroblast which was cultured from human embryonic skin were divided into 3 groups: Insulin group, Danshen group and contral group. Each group was cultured for 2, 4 and 6 days, then the growth curve was established respectively. RESULTS: 1. The growth curve showed-insulin group > control group > Danshen group. 2. The rate of cell division in 3 groups was 19.6/1000, 2.5/1000, 3.77/1000 respectively. 3. The electron microscopic scanning showed that there was much of fibroid tissue surrounding the fibroblast cell in insulin group, but there was little fibroid tissue in Danshen group. The conclusion showed that insulin can accelerates proliferation of fibroblast and synthesis of collagen, but the effect of denshen was just on the contrary.

Cell Division↗

PubMed1998

[Esophageal reconstruction using ilecolon in children--a report of ten cases].

The use of the ileocolon as a substitute for esophagus in children has been a well-established surgical procedure. Between 1992 and 1995, ten retrosternal esophageal substitutions using an ileocolic interposition were performed. The ages of the children ranged from 2 to 8 years. The esophageal strictures were secondary to ingestion of caustic liquid. No death occurred in the intra- and post-operation period. Cervical ileoesophageal anastomotic leaks took place in 2 cases as the early major postoperative complications, which healed spontaneously. Three cases of ileoesophageal anastomotic strictures were noted in the follow-up period. The surgical indications, the treatments of anastomotic leaks and strictures, and the importance of long-term follow-up were discussed.

Burns, Chemical↗

PubMed1998

[A retrospective study of neurogenic pulmonary edema following intracranial injury without open wound].

To find factors that relate to the occurrence of neurogenic pulmonary edema(NPE) following intracranial injury without open wound, thirty-founr autopsies on such cases were studied retrospectively. The rate of NPE in the 34 cases was 41.18%, and it was 44.44% in those aged 10 to 49. The rate of NPE in the persons who died immediately or 0-6 hours after injury was 41.18%, and in those who died 7-48 hours after injury, 41.18% too. The rate of NPE was 69.23% for the cases with only one site of bleeding and 23.81% for ones with multiple sites of bleeding. These findings suggest that the occurrence of NPE is not related with the duration of time after head injury or the location of brain injury, but it is related with the severity of brain injury.

Adolescent↗

PubMed1998

[Quantitive analysis of 5-hydroxytryptamine levels on edges of incised skin of rats].

To find index for early diagnosis of antemortem wound, the authors used the ICS analysis in a quantitive study of 5-hydroxytryptamine(5-HT) levels on rat's incised-skin antemortem wound in comparison with the postmortem wound inficted at various intervals. The results showed that the 5-HT increased significantly at 5 min, reached a peak at 15 min and decreased at 60 min on antemortem wounds. The 5-HT levels of antemortem groups were prominently high (more than 40%, P < 0.05) as compared with those of postmortem group and the levels of 5-HT on the wounds of postmortem groups were higher (35.77%, P < 0.05) than those of controls as well. The authors suggest that in the cases where the levels of 5-HT are as high as 40% on the edges of the injured skin, the injury should be considered an antemortem wound.

Animals↗

PubMed1998

[Applied anatomy of the vascularity in the ileocolic region and its clinical significance].

To understand the characteristics of the patterns of arteries and veins distributed over the ileocolic segment, 50 cadavers were studied by gross-anatomy. The arteries, veins and their paracolic anastomoses distributed over ileocecal region, ascending colon and transverse colon were observed. The results showed that the distribution pattern of venous vessel was far more constant than that of artery, that the arrangements of artery in the ileocolic segment were classified into 7 types, and there were no interruption of paracolic anastomoses between arteries. But in 3 specimens the paracolic anastemoses between the right colic vein and the middle colic vein were completely interrupted. These findings may be useful in guiding clinical practice and preventing postoperative complications in ileocolic replacement of esophagus.

Adult↗

PubMed1998

[Analysis of amino acids, vitamins and inorganic elements in Dictyophora indusiata].

Fifteen amino acids(total content: 13.37 mg.100 ml-1), 12 inorganic elements(Zn 37.3 micrograms.g-1, Mn 56.9 micrograms.g-1, Cr 4.88 micrograms.g-1, Fe 370 micrograms.g-1, Se 0.81 microgram.g-1, Cu 28.2 micrograms.g-1, Co 0.78 microgram.g-1, Ni 2.09 micrograms.g-1, etc.), and vitamin E(73.2 micrograms.g-1) in Dictyophora indusiata were determined. Seven amino acids, including valine 0.61, leucine 1.04, isoleucine 0.66, threonine 0.74, methionine 0.20, lysine 0.52, and pheuylalanine 0.64(mg.100 mg-1), were found to be essential. The possible medical significance of Dictyophora indusiata is discussed.

Amino Acids↗

PubMed1998

[Expression of p16 gene in malignant lymphoma detected by immunohistochemical and in situ hybridization techniques].

OBJECTIVE: To investigate the expression of p16 gene in non-Hodgkin's lymphoma (NHL) and its clinicopathological significance. METHODS: Paraffin embedded biopsies from 64 patients with NHL were analysed for p16 gene expression by immunohistochemical methods and in situ hybridization technique. RESULTS: Of the 64 NHL cases, 34(53.1%) were positive for p16 protein, 30(46.9%) lacked p16 protein, most of the positive signals were seen in the nuclei; 45(70.3%) were p16 mRNA positive, 19(29.7%) lost p16 mRNA and p16 mRNA was clearly observed in the cytoplasm of lymphocytes. p16 expression did not show correlation with such factors as sex, age and immunophenotype in NHL, but there was a significant difference between the pattern of expression of p16 in well differentiated lymphomas and poorly differentiated lymphomas (P < 0.05). Moreover, 42 patients were followed postoperatively for over 3 years, both p16 protein and mRNA correlated with the prognosis of these patients. CONCLUSION: There was a higher incidence of negative expression of p16 mRNA and protein in NHL, which indicates that p16 gene inactivation may play an important role in the genesis and development of some NHL. The frequency of negative expression of p16 mRNA was lower than that of p16 protein suggests that it may be due to post-transcriptional regulation or the unsteadiness of mRNA or protein expressed. The positive expression of both p16 mRNA and p16 protein may be features for favorable prognosis in patients with NHL.

Adolescent↗

PubMed1998

Androgen receptor in primary hepatocellular carcinoma and its clinical significance.

OBJECTIVE: To assess retrospectively the clinical value of androgen receptor (AR) levels in primary hepatocellular carcinoma (HCC) as a prognostic factor of the disease. METHODS: Fresh HCC tissue and the surrounding liver tissue were obtained surgically from 32 patients with HCC, and preserved in liquid nitrogen. The levels of AR in all specimens were determined by radio-ligand binding assay. RESULTS: The median level of AR was 42.8 fmol/mg protein in the cancerous tissue and 48.3 fmol/mg protein in the surrounding non-cancerous liver tissue. The overall survival rate of the patients with AR < 30 fmol/mg protein in either HCC or the non-cancerous liver was significantly higher than that of the patients with AR > or = 30 fmol/mg protein (P < 0.05 and P < 0.01, respectively). The relative risk on prognosis was 3.27 (P < 0.01) for AR level in HCC and 6.06 (P < 0.001) for AR level in the non-cancerous tissue. The main prognostic factors except the tumor size were not different between the group with higher AR level and that with lower AR level in HCC. The AR level in HCC had a positive correlation with the tumor size (r = 0.44, P < 0.05). CONCLUSIONS: AR can be detected in HCC and the AR status might be a prognostic parameter that provides additional predictive information on the survival. Different AR status might define a real difference of biological characteristics between HCCs.

Adult↗

PubMed1998

[Clinical observation on effect of yangjing decoction in promoting follicular growth].

OBJECTIVE: To investigate the effect of Yangjing Decoction (YJD, a Chinese prescription of replenishing Kidney essence) in promoting follicular growth and its influence on blood supply of ovary and uterus. METHODS: Twenty-two cases with secondary amenorrhea and 4 cases of infertility with infrequent menstruation caused by follicle maldevelopment were treated with YJD. The blood supply of ovary and uterus in 7 cases was measured by colour Doppler before and after treatment. RESULTS: Of the 116 therapeutic cycles in 26 cases, there were 69 menstrual cycles (59.48%), 37 follicular maturation cycles (31.90%), 21 ovulation cycles (18.10%), and the follicular maturation rate was 84.62%, The disturbance in blood supply of ovary and uterus was improved remarkably along with follicular development by YJD in 7 cases. CONCLUSION: YJD could improve follicular development and blood supply of ovary and uterus.

Adult↗

PubMed1998

Influence of space conditions on photosynthetic pigment contents and chloroplast ultrastructure of maize leaves.

Dried seeds of maize inbred lines were carried by recoverable satellite to space conditions at an altitude of 175-253 km from sea level for 15 d. The effects of space flight on ultrastructure and photosynthetic pigment contents of maize leaves were studied. Various changes in structure were observed. Chloroplast envelope membrane notch, swelling of thylakoids, less granum stacks and stroma thylakoid membranes, and changes of chloroplast contour were often seen. The contents of chlorophyll a, chlorophyll b, and chlorophyll a+b and carotenoids tended to be lower, but Ca/Cb ratio tended to be higher in the leaves from space flight maize in comparison with ground control.

Chlorophyll↗

PubMed1998

[Isolation and identification of Triterpenoid compounds in the fruits of Chaenomeles lagenaria (Loisel.) Koidz].

OBJECTIVE: The fruit of Chaenomeles lagenaria is a commonly used drug in Chinese traditional medicine. It is especially effective on rheumatism. The current work is to find out the chemical basis of its pharmacological activity. METHOD: All compounds were extracted with organic solvents and separated by silica gel column or thin layer chromatography, and then purified by recrystalization. The structures were elucidated on the basis of chemical reactions and spectral data analysis. RESULT: In addition to the compounds reported in our previous work, three triterpenoid compounds were separated and identified as 3-O-acetyl ursolic acid, 3-O-acetyl pomolic acid and betulinic acid respectively. CONCLUSION: It is obvious that triterpenoid compounds are dominant among the chemical constituents of C. lagenaria. But it is still to be clarified whether they are the chemical basis of the drug's pharmacological activity.

Drugs, Chinese Herbal↗