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D Liu

Publications and source records attributed to D Liu.

At least 487 records · Page 27Linked to original sources
PubMed1997

Factors controlling the efficiency of cationic lipid-mediated transfection in vivo via intravenous administration.

The factors controlling the transfection efficiency of cationic lipid carrier systems following intravenous administration are poorly understood. Using N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) combined with Tween 80 as a carrier system and cDNA of luciferase or beta-galactosidase gene as a reporter, we investigated the importance of DOTMA to DNA ratio and the ratio of DOTMA to Tween 80 in the lipid formulation in determining the site and level of transgene expression following intravenous administration. The data show that all of the internal organs, including lung, liver, spleen, heart and kidneys, expressed the transgene upon systemic administration into animals with 25 micrograms of plasmid DNA when complexed with DOTMA-Tween 80 lipid formulation. The transfection efficiency was dependent on both DOTMA to DNA, and DOTMA to Tween 80 ratios. Among the organs examined, the lung appeared to be more transfectable than other organs. A better transfection activity was obtained with higher DOTMA to DNA and DOTMA to Tween 80 ratios. Time-response curve shows that gene expression was transient with a maximal level between 10 and 24 h after injection. Results from tissue distribution studies with 125I-labeled plasmid DNA and Southern analysis suggest that the transient expression is the result of the loss of transgene from the transfected cells. These results suggest that cationic lipid-based delivery systems can be efficient for gene delivery if the composition of the DNA-lipid complexes is properly controlled.

Animals↗
PubMed1997

Molecular determination of dermatophyte fungi using the arbitrarily primed polymerase chain reaction.

Dermatophytes are keratinophilic fungi capable of causing dermatophytosis (commonly known as tinea or ringworm) in humans and animals. Previously, we reported the differentiation of the common dermatophytes Trichophyton rubrum, T. mentagrophytes and T. tonsurans using a random primer 5'-ACCCGACCTG-3' (OPAA11) in the arbitrarily primed polymerase chain reaction (AP-PCR). In the present study, by examining additional dermatophytes including eight Microsporum spp., 16 Trichophyton species/subspecies and Epidermophyton floccosum using both OPAA11 and a second random decamer 5'-GAGAGCCAAC-3' (OPD18) in AP-PCR, we show that except for T. rubrum and T. gourvilli, and three T. mentagrophytes varieties, most of the dermatophyte fungi investigated formed distinct DNA band patterns on gel electrophoresis. The amplification of specific DNA bands in AP-PCR appeared to be independent of culture variations shown by dermatophyte isolates. These results provide the basis for the rapid identification of dermatophytes at the genetic level, supplementing existing laboratory methods and improving the diagnosis of human dermatophytosis.

Arthrodermataceae↗
PubMed1997

Structural analysis of the proximal region of the microtubule-associated protein 1B promoter.

Microtubule-associated protein 1B (MAP1B) is a major cytoskeletal protein expressed early during development of the nervous system. Previous analysis of the MAP1B gene has identified two alternative promoters that can independently regulate neuron-specific expression of MAP1B. To further characterize the MAP1B promoters, we performed DNase I hypersensitivity assays in vivo over a range of 8.5 kb surrounding the transcription initiation sites. These studies identified a DNase I-hypersensitive site that was present in brain but not liver nuclei at the proximal region of the MAP1B promoter, located between the two transcription initiation sites. Fine mapping by S1 nuclease sensitivity localized two adjacent sites in the proximal promoter region that contained three symmetrical inverted repeats. Electrophoresis mobility shift assays showed that proteins present in nuclear extracts can bind two consensus regulatory elements present within the proximal promoter region, Sp1 and cyclic AMP response element. In addition, there was a specific nuclear protein binding activity with two common sequences, a "neuronal motif " and a TCC repeat motif. This binding activity was much more abundant in liver than in brain nuclear extracts, suggesting that it may represent a negative control element in the tissue-specific expression of the MAP1B gene.

Animals↗
PubMed1997

CD44 as a marker in human cancers.

Tumor metastasis is one of the most life-threatening aspects of tumor progression in patients with cancer. One of the cell surface molecules that has been implicated to play an important role in tumor metastasis is CD44. Earlier results provide the initial optimism that CD44 isoform expression may be a marker for human cancers. However, more recent studies revealed that regulation of CD44 isoform expression is a complex and not well-understood phenomenon. Expression of CD44 in tumor cells can be regulated quantitatively by increasing the expression of one particular CD44 isoform or quantitatively by altering the expression of CD44 isoforms. Downregulation of CD44 is important in the metastasis of some tumor cells. We summarize some of the recent results on the potential of CD44 as a diagnostic or prognostic marker for patients with cancers.

Antigens, Neoplasm↗
PubMed1997

PCR identification of Trichophyton mentagrophytes var. interdigitale and T. mentagrophytes var. mentagrophytes dermatophytes with a random primer.

Dermatophytes are a group of keratinophilic fungi falling within the genera of Epidermophyton, Microsporum and Trichophyton. The genus Trichophyton is particularly important and complex; it comprises at least 15 recognised species. In addition, there are several different variants in the species T. mentagrophytes, which occur both in man and animals. The current methods of determining T. mentagrophytes varieties may require several different culture media and time-consuming procedures, as well as specialist skills. This study used a random primer, 5'-GAGCCCGACT-3', in the arbitrarily primed polymerase chain reaction (AP-PCR) and showed that the two common T. mentagrophytes varieties (var. interdigitale and var. mentagrophytes) can be clearly identified on the basis of their characteristic DNA band patterns. The relative reproducibility, ease of use and precision of this method make the AP-PCR a valuable tool in the laboratory diagnosis of human dermatophytosis.

DNA Primers↗
PubMed1997

Tag1 is an autonomous transposable element that shows somatic excision in both Arabidopsis and tobacco.

Tag1 is a transposable element first identified as an insertion in the CHL1 gene of Arabidopsis. The chl1::Tag1 mutant originated from a plant (ecotype Landsberg erecta) that had been transformed with the maize transposon Activator (Ac), which is distantly related to Tag1. Genomic analysis of untransformed Landsberg erecta plants demonstrated that two identical Tag1 elements are present in the Landsberg erecta genome. To determine what provides transposase function for Tag1 transposition, we examined Tag1 excision in different genetic backgrounds. First, the chl1::Tag1 mutant was backcrossed to untransformed wild-type Arabidopsis plants to remove the Ac element(s) from the genome. F2 progeny that had no Ac elements but still retained Tag1 in the CHL1 gene were identified. Tag1 still excised in these Ac-minus progeny producing CHL1 revertants; therefore, Ac is not required for Tag1 excision. Next, Tag1 was inserted between a cauliflower mosaic virus 35S promoter and a beta-glucuronidase (GUS) marker gene and transformed into tobacco. Transformants showed blue-staining sectors indicative of Tag1 excision. Transgenic tobacco containing a defective Tag1 element, which was constructed in vitro by deleting an internal 1.4-kb EcoRI fragment, did not show blue-staining sectors. We conclude that Tag1 is an autonomous element capable of independent excision. The 35S-GUS::Tag1 construct was then introduced into Arabidopsis. Blue-staining sectors were found in cotyledons, leaves, and roots, showing that Tag1 undergoes somatic excision during vegetative development in its native host.

Arabidopsis↗
PubMed1997

Neurotrophic factors are required by mature sympathetic neurons for survival, transmission and connectivity.

1. Two neuronal growth factors, nerve growth factor (NGF) and neurotrophin 3 (NT3), have been studied for their action on the developing and mature sympathetic nervous system. 2. Antibodies to each factor have proved useful as reagents for the detection and quantification of NGF and NT3. They have also proved valuable in uncovering the functional roles of each factor by their ability to neutralize the endogenous molecules. 3. Nerve growth factor acts on postnatal neurons to control neurotransmission, connectivity and survival. Like NGF, NT3 is synthesized by effector tissues and is retrogradely transported by post-ganglionic neurons to prevent cell death. However, the two factors have been shown to have quite distinct functions in mature neurons, indicating the existence of different signalling pathways. This differential action extends to secondary influences on satellite glia. 4. Pathological consequences result from excessive growth factor synthesis leading, in the hypertensive rat, to hyperinnervation and elevated blood pressure. Satellite glial cell synthesis of the factors and their receptors following peripheral nerve damage appears to be responsible for the establishment of inappropriate neuronal connections between sympathetic nerve terminals and sensory somata. 5. It is concluded that these potent factors control, by both coincident and independent mechanisms, sympathetic neuronal function throughout the life of the animal.

Animals↗
PubMed1997

Amniotic membrane collagen content and type distribution in women with preterm premature rupture of the membranes in pregnancy.

Amniotic membrane samples were taken following preterm delivery from 15 women with preterm prelabour rupture of the membranes (PPROM) and 14 with unrelated reasons, and from 25 delivering at term. Fibrillar collagens were extracted and analysed by interrupted gel electrophoresis. Collagens were decreased in PPROM relative to controls, but showed similar sub-type distribution, with one exception. In this case an increased ratio of Type I to Type III collagen was observed, with normal collagen content. In conclusion, PPROM is accompanied by generalised reduction in amnion collagen content, involving all fibrillar sub-types monitored. This may reflect general changes in protease activity or in collagen expression in affected membranes.

Amnion↗
PubMed1997

Stable human immunodeficiency virus type 1 (HIV-1) resistance in transformed CD4+ monocytic cells treated with multitargeting HIV-1 antisense sequences incorporated into U1 snRNA.

We have approached the development of a human immunodeficiency virus type 1 (HIV-1) therapeutic product by producing immune cells stably resistant to HIV-1. Promonocytic CD4+ cells (U937) were made resistant to HIV-1 by the introduction of a DNA construct (pNDU1A,B,C) that contained three independent antisense sequences directed against two functional regions, transactivation response and tat/rev, of the HIV-1 target. Each sequence was incorporated into the transcribed region of a U1 snRNA gene to generate U1/HIV antisense RNA. Stably transfected cells expressed all three U1/HIV antisense transcripts, and these transcripts accumulated in the nucleus. These cells were subjected to two successive challenges with HIV-1 (BAL strain). The surviving cells showed normal growth characteristics and have retained their CD4+ phenotype. In situ hybridization assays showed that essentially all of the surviving cells produced U1/HIV antisense RNA. No detectable p24 antigen was observed, no syncytium formation was observed, and PCR-amplified HIV gag sequences were not detected. Rechallenge with HIV-1 (IIIB strain) similarly yielded no infection at a relatively high multiplicity of infection. As a further demonstration that the antisense RNA directed against HIV-1 was functioning in these transfected immune cells, Tat-activated expression of chloramphenicol acetyltransferase was shown to be specifically inhibited in cells expressing Tat and transactivation response region antisense sequences.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Diabetes and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS): radiolabeled polymerase chain reaction is necessary for accurate detection of low percentages of mutation.

A 6-yr-old boy presented with muscle weakness, lactic acidemia, and insulin-dependent diabetes mellitus (IDDM). Using PCR and restriction enzyme analysis, he was found to have the classical A3248G mitochondrial DNA (mtDNA) mutation frequently associated with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS). The mutation was confirmed by sequencing muscle mtDNA. The mutation in mtDNA from muscle, lymphoblasts, and blood was clearly demonstrable by standard methods using ethidium bromide staining. His mother also had IDDM, but no A3243G mutation could be detected in her blood or transformed lymphoblasts using the same PCR technique. When PCR was carried out in the presence of [32P]deoxycytidine triphosphate, subsequent autoradiography detected the presence of the mutation at low levels in mtDNA from the mother's lymphoblasts and blood. Study of the mother's muscle showed a mitochondrial myopathy, despite the fact that she was asymptomatic. We emphasize that the increased sensitivity of radiolabeled PCR may be necessary to detect small percentages of heteroplasmic A3243G mtDNA mutation in blood from diabetic subjects. Otherwise the incidence of mtDNA mutations in both IDDM and non-insulin dependent diabetes may be underestimated.

Adult↗
PubMed1997

Teleost FTZ-F1 homolog and its splicing variant determine the expression of the salmon gonadotropin IIbeta subunit gene.

Steroidogenic factor 1, a member of the fushi tarazu factor 1 (FTZ-F1) subfamily of nuclear receptors, is a key regulator in mammalian reproduction. From an embryonic complementary DNA library, the zebrafish homolog of FTZ-F1 (zFF1A) and an alternatively spliced variant (zFF1B) were isolated. zFF1B represented a C-terminally truncated version of zFF1A. Whole mount in situ hybridization and reverse transcriptase-PCR analysis revealed that both zFF1A and B transcripts were present in the developing pituitaries, adult fish brain, gonads, and liver, albeit zFF1B messenger RNA was absent in testis. Comparison of the primary sequences of zFF1 with those of other FTZ-F1 subfamily members showed a close structural relationship between the mouse liver receptor homolog, which activated the alpha1-fetoprotein gene in rodent liver. However, similar to mouse steroidogenic factor 1, zFF1A regulated chinook salmon gonadotropin IIbeta subunit gene expression. On the contrary, zFF1B, which could bind a consensus gonadotrope-specific element with an affinity similar to that of zFF1A, lacked both the trans-activation function and synergistic interaction with the estrogen receptor. Furthermore, cotransfection studies in HeLa cells showed that zFF1B was a strong competitor for the action of zFF1A on the chinook salmon gonadotropin IIbeta subunit gene promoter. Our investigation suggests that 1) zFF1 represents an ancestor protein of the vertebrate FTZ-F1 homologs; 2) the antagonistic relationship between zFF1A and -B may dictate the expression of the FTZ-F1 target genes in a variety of tissues, including the pituitary; and 3) the naturally occurring zFF1B provides evidence that the C-terminal portion of zFF1A (80 amino acid residues) contains a major trans-activation function and a protein-protein interface.

Amino Acid Sequence↗
PubMed1997

[Relationship between p16 and Rb protein expression in astrocytomas].

OBJECTIVE: p16 and Rb protein were examined in primary astrocytomas in order to study the correlation between p16 and Rb proteins. METHODS: p16 and Rb pretoin were immunostained by SP immunohistochemical method in the sections of formalin fixed paraffin embedded tumor tissue from 102 patients with astrocytoma brain tumors. RESULTS: p16 and Rb protein were expressed in all low grade (WHO Grade I and II) astrocytomas but only in 48.1% and 57.4% astrocytomas of Grade III and Grade IV respectively, in which, 24/31 of Rb protein positive tumors showed null or low expression of p16 protein, while 19/23 of Rb negative tumors were associated with positive or high level expression of p16 protein. CONCLUSIONS: (a) p16 and Rb proteins were both involved in astrocytoma progression. (b) Negatively correlated pressionof p16 and Rb protein might be one of characteristics of malignant astrocytoma.

Astrocytoma↗
PubMed1997

[The proliferation inhibition and differentiation inducing effects of all-trans retinoic acid on human pancreatic adenocarcinoma cell line JF-305].

We detected the antiproliferative effect with MTT test and investigated the changes in biological properties, cytomorphology and ultrastructure through cytopathology and electronic microscopy. Cell growth of JF-305 was inhibited by all-trans retinoic acid (ATRA). The maximal inhibitory rate was 34.7%. The number of proliferative cells reduced (P < 0.01). Cell metabolism slowed down, secretory functions recovered, and malignant degree decreased. ATRA can inhibit the proliferation and induce the differentiation of human pancreatic adenocarcinoma JF-305 cells.

Adenocarcinoma↗
PubMed1997

[Prospective study of central venous catheter-related sepsis in critically ill patients].

To evaluate the incidence of central venous catheter-related sepsis (CRS) in critically ill patients, we performed a prospective study of the central venous catheters (CVCs) in ICU of the Peking Union Medical College Hospital from Jan. 1995 to March 1996. Of 151 CVCs, 13 (8.6%) had CRS, with an incidence of 16.7 episodes per 1000 catheter-days. Presence of infectious focus at catheterization, catheter insertion site, duration of catheterization, and the decrease of body temperature after catheter removal correlated with definite CRS, while difficulty of insertion, body temperature at catheter removal, as well as the decrease of body temperature after catheter removal correlated well with no CRS. The study showed that CRS is a serious problem in critically ill patients. Careful manipulation of CVCs is a major determinant in reducing the incidence of CRS.

Catheterization, Central Venous↗
PubMed1997

[Clinical study of systemic inflammatory response syndrome and multiple organ dysfunction syndrome in critically patients].

We defined the epidemiology of systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) in critically ill patients, and evaluated the procession from SIRS to MODS and the therapeutic strategies. 230 patients were studied prospectively until discharge or death. On admission, the morbidity rate of SIRS was 71.3%. The mortality rate of the patients with SIRS was 18.9%. MODS was developed in 65 patients (28.3%), and 33 patients dided (50.8%). In SIRS patients with non-infectious SIRS, sepsis and septic shock, the morbidity rates of MODS were 22.8%, 61.1% and 85.7%, and the mortality rates were 11.4%, 30.6% and 50.0% respectively. The outcome of critically ill patients may be improved if SIRS is early diagnosed and the body inflammatory response is reglulated properly.

China↗
PubMed1997

[Factors for postoperative persistent hypertension in patients with aldosterone-producing adenoma].

We determined the factors for postoperative persistent hypertension in the patients with aldosterone-producing adrenal adenoma (APA) in 53 patients with APA who were followed up for average 3.1 years. All had normal serum potassium concentration postoperatively. Blood pressure was normal in 37 patients (69.8%) but 18.7/12.7 kPa or more in 16 patients (30.2%) with persistent hypertension. Also compared were sex, age, history of hypertension, effect of reducing blood pressure to antisterone, preoperative blood pressure, time of persistent hypertension, serum potassium concentration, aldosterone concentration in 24 hour urine, amount of PRA, and the type of operation. The results showed that an APA patient aged 50 years or more appears to have a great chance of persistent hypertension than an APA patient under age of 40 years, and the odds ratio is 3:1. There was a significant difference between the mean age for persistent hypertension and for normal blood pressure, and varioas response of reducing blood pressure to antisterone (P < 0.05). It is suggested that for an older APA patient and the patient without of reducing blood pressure to antisterone, there are other factors for hypertension such as renal veinlet change or renal interstitial lesions except for hyperaldosteronism. We recommend renal biopsy (using kidney puncture) at the operating table for those patients in order to understand pathological change and guide treatment after operation.

Adenoma↗
PubMed1997

[Diagnostic value of CD44 splice variants in urine exfoliated cells of bladder cancer].

To study the early and non-invasive diagnostic value of CD44 splice variants in urine exfoliated cells of bladder cancer. We used reverse transcriptionpolymerase chain resection (RT-PCR) and southern blot hybridization to detect CD44 splice variants in exfoliated cells in 40 urine samples (20 bladder cancers, 20 non-neoplastic controls), and compared with the results of urine cytology on the same set of samples. 90% (18/20) of the urine samples of bladder cancer showed overexpression of CD44 splice variants while none of the 20 controls did so. This method not only has a sensitivity of 90% (18/20) which was much higher than that of 65% (13/20) by using urine cytology, but also is non-invasive and comfortable. The results suggest that CD44 splice variants in exfoliated cells in urine samples are a new tumor marker for early and non-invasive diagnosis of bladder cancer.

Biomarkers, Tumor↗