Biomedical subjects

D Liu

Publications and source records attributed to D Liu.

At least 451 records · Page 25Linked to original sources

PubMed1998

[An observation on antiviral effect of IFN--alpha N1 (Wellferon) in patients with chronic hepatitis B].

In order to observe the antiviral effect of IFN-alpha N1(Wellferon, British Glaxowellcome Company) on CHB, each 50 cases of CHB were selected as the therapy group and the control group. The patients in the therapy group were administrated with 3MU of IFN-alpha N1 once a day for one week, and then 3MU of IFN-alpha N1 three times weekly for 11-23 weeks, whereas the patients in the control group did not receive any antiviral treatment. At 3 months, the serum alanine transaminsae(ALT) was decreased to normal level in 84%(42/50) cases of the therapy group, while only in 46% (23/50) cases of the control group (P < 0.01). The negative seroconversion rate of HBeAg was 56.7% (17/30) and 10.8% (4/37), of HBV DNA was 36.4%(12/33) and 5.9% (1/17) in therapy and control groups respectively. There was obvious difference in two groups. The results suggest that IFN-alpha N1 is satisfying antiviral drug for CHB patients or patients non-responsive to other IFNs.

Adult↗

PubMed1998

[Detection of GBV-C/HGV infection in patients with liver diseases].

The aim of this article is to study the prevalence of GBV-C/HGV in patients with liver diseases and the clinical features in patients with (GBV-C/HGV infection. The serum samples were obtained from 169 patients with liver diseases in You An Hospital). Serum GBV-C/HGV RNA was detected by reverse transcription nested polymerase chain reaction (RT-nPCR) using two primer pairs of 5' untranslated region (5' UTR) of HGV. Serum anti-HGV was detected by ELISA simultaneously. The partial GBV-C/HGV genome isolated from one patient was cloned into T vectors and sequenced by dideoxy-mediated chain termination methods. Among 169 patients with various liver diseases, the GBV-C/HGV RNA positive rate was 9.5% (16/169), including 11.1% (1/9) of AHA, 4.1% (3/73) of CHB, 16.2% (6/37) of CHC, 13.3% (2/15) of AH(nonA-E) 12.5% (1/8) of CH(nonA-E) 15.4% (2/13) of LC and 33.3% (1/3) of SH cases. Of 29 patients having a history of surgical operation and transfusion, 9(31.0%) was positive for GBV-C/HGV RNA, which was remarkably higher than those cases without surgical operation and transfusion. The sequence analysis showed that there was 89.14%-98.91% nucleotide identity between our isolate and published GBV-C/HGV isolates. The results also suggested that infection rate of GBV-C/HGV was around 9.5% in patients from Beijing region, patients with GBV-C/HGV infection might show various clinical features and GBV-C/HGV might not be the major cause of hepatitis nonA-E.

5' Untranslated Regions↗

PubMed1998

[Studies on actinomycetes population from salt lake of Yuncheng in Shanxi].

120 strain of mesophilic and thermophilic of alkalaphilic actinomycetes of alkalic tolerant actinomycetes isolated from Yuncheng salt lake in Shanxi were identified. On the basis of morphological characteristics and some chemotaxonomic properties (composition of cell wall, whole cell sugar), the isolated strains were classified into Nocadiopsis, Micromonospora, Actinomadura and Streptomyces. The Streptomyces strains were classified into 11 groups.

Actinomycetales↗

PubMed1998

[Design and study of carbon fiber tracheal prosthesis].

32 healty adult dogs were selected for this experiment. 10 of them were subjected to the tracheal biomechanics test using indices including the relation between stretcher ratio (lambda) and stress (T), the squeeze stress (delta jy) of medical silk thread on trachea, the side stress (Ts) inducing the tracheal collapse, the functional maximum angle (psi max) of tracheal, and the sever area torsion angle (theta max) of tracheal functional maximum curved. According to the indices measured, two types of tracheal prosthesis were designed, and were made of carbon fiber and silicon. They were the straight tube type tracheal prosthesis and the bifurcate type tracheal prosthesis. The straight tube type tracheal prosthesis was studied with a design of two groups comprising a total of 11 dogs. In the experiment group (n = 6), the outer surface of the tube was not coated with silicon, the average survival period was 379.8 days. In the control group (n = 5), the outer surface of the tube was coated with silicon, the average survival period was 90.4 days. The bifurcate type tracheal prosthesis was studied in 11 dogs, the average survival period was 4.32 days. The main causes of death in the experiment were infection and anastomotic dehiscent.

Animals↗

PubMed1998

[Effects of hairy root huangqi on hemopoietic function].

The effects of hairy root Huangqi on hemopoietic system were studied in this paper. The oral administration of 5-20 g/kg hairy root Huangqi per day for 5-12 days could increase the count of RBC and reticulocytes in mice with hemorrhagic anemia, raise the hemoglobin, RBC and hematocrit in mice with hemolytic anemia, enhance the number of WBC and nucleared cells in bone marrow of mice treated with cyclophosphamidum or x-rays. The experiments showed that hairy root Huangqi promoted the hemopoietic function. The effects were similer to those of natural Huangqi.

Anemia, Hemolytic↗

PubMed1998

[FTIR microscope study on the change of membrane protein and lipids of erythrocyte damaged by free radicals].

The FTIR Microscope and Computer Aided Analysis were used to study not only the change of secondary structure of erythrocyte membrane protein attacked by the free radicals, but also the effect of oxygen centered free radicals on the membrane lipids in this paper. The results indicate that the content of alpha-helix in the secondary structure of protein clearly changed because of the attack of the free radicals. Damaged by free radicals in 30 minutes, the protein structure could not be restored after 3 hours. The number of the P=O (vp=0), C=O and C=C in the lipids of the membrane was changed. These changes were caused by the peroxidation of the oxygen centered free radicals.

Adult↗

PubMed1998

[Comparative study on the hydration of phosphate group in H2O/NaDEHP/n-heptane and H2O-TBP systems by FT-IR].

The hydrations of phosphate group in both tributyl phosphate (TBP)-H2O system and water/NaDEHP/n-heptane reverse micellar system have been studied using Fourier transform infrared spectroscopy (FT-IR). Water content (W0 = [H2O]/[TBP]) in TBP solutions was measured quantitatively using FT-IR. In water/NaDEHP/n-heptane reverse micellar system, the stretching frequencies of phosphate group shifted from 1229 to 1200cm(-1) when water content increased from 1 to 25. For TBP-H2O system, P=O stretching band varied from 1281.33 to 1263cm(-1) with the increasing water content (from 0.33 to 1.55). P=O stretching bands in TBP-H2O system were also found to split into two peaks located around 1283 and 1260cm(-1) after the bands were resolved by curve-fitting. All these variations are attributed to the hydration of phosphate in the two systems.

English Abstract↗

PubMed1998

Medical and surgical management of pulmonary metastases from germ cell tumors.

GCT is considered a curable tumor with a greater than 90% overall long-term survival. Pulmonary metastasis is common in patients with disseminated disease. First-line therapy in the management of patients with pulmonary metastases from germ cell tumors is cisplatin-based chemotherapy. Pulmonary metastasectomy has an important adjuvant role in a subset of patients who have residual radiographic abnormalities or progression of disease despite optimal chemotherapy. Surgical resection of residual pulmonary and mediastinal disease provides an accurate response assessment and consolidates the chemotherapy by removal of any viable GCT. Therefore, surgical resection of all residual masses is indicated in patients with NSGCT and normalized serum value of tumor markers after definitive systemic chemotherapy. Surgical resection or biopsy is a reasonable alternative in residual seminoma > or = 3 cm in diameter.

Antineoplastic Agents↗

PubMed1998

High Raf-1 kinase activity protects human tumor cells against paclitaxel-induced cytotoxicity.

Paclitaxel (Taxol) is becoming increasingly important in the treatment of many tumors, although a large proportion of tumors fail to respond to this drug. The identification of the processes that confer cellular paclitaxel resistance could provide potential targets for novel therapies that may help to eliminate paclitaxel-resistant tumors. Recent reports suggest that the Raf-1 protein kinase may have a profound influence on the level of paclitaxel-induced apoptosis. We have critically evaluated the relationship between Raf-1 kinase activity and de novo paclitaxel resistance in early-passage human cervical tumors. In the 12 cell lines studied, Raf-1 kinase activity was inversely correlated (P = 0.0016) with the level of cytotoxicity induced by 60 nM paclitaxel. The relationship between these two parameters seems to be more than an epiphenomenon, because genetic down-regulation of Raf-1 kinase activity led to an approximately 4-fold increase in paclitaxel-induced cytotoxicity. The data from both our transfection studies and those on the 12 unperturbed cell lines are consistent with Raf-1 kinase being a negative determinant of paclitaxel-induced cytotoxicity. Because the cytotoxicity of paclitaxel is primarily attributable to apoptosis, these data suggest that Raf-1 kinase acts to suppress paclitaxel-induced apoptosis. These data suggest that the clinical effectiveness of paclitaxel could be substantially improved by the use of Raf-1 kinase inhibitors, provided that a similar relationship between Raf-1 kinase activity and paclitaxel cytotoxicity exists in the clinic, especially in those tumor sites where paclitaxel is the current treatment of choice e.g., ovarian and breast cancer.

Antineoplastic Agents, Phytogenic↗

PubMed1998

An investigation of the relationship between estrogen, estrogen metabolites and blood cholesterol levels in ovariectomized rats.

17 beta-Estradiol (E2) has long been known for protecting against coronary heart disease by lowering cholesterol levels in premenopausal women. A recent study in our laboratory suggested that two hydroxylated metabolites of E2 possess similar hypocholesterolemic effects in male rats. This effect has been further investigated with additional estrogen metabolites in ovariectomized rats with a view toward mimicking the true postmenopausal situation in humans. Their effects in reproductive tissues were also evaluated histologically. Fundamentally, the following issues were addressed: (1) Do oxidized metabolites of estradiol lower total cholesterol levels? (2) Can a hypocholesterolemic effect be achieved without eliciting estrogenic activities on reproductive tissues? The results of this investigation showed that a number of oxygenated metabolites of estradiol can lower cholesterol levels. Among them, 4-hydroxyestradiol (4-OHE2) produced a striking hypocholesterolemic effect and a substantial uterotropic effect. 2-Hydroxyestradiol (2-OHE2), 2-methoxyestradiol (2-meoE2) and 2-methoxyestrone (2-meoE1) produced a significant decrease in cholesterol levels at doses that did not produce significant uterotropic effects.

Animals↗

PubMed1998

GABAergic effects on nucleus tractus solitarius neurons receiving gastric vagal inputs.

Single units in the region of the medial nucleus tractus solitarius (NTS), responding to electrical stimulation of gastric vagal fibers, were recorded in an in vitro neonatal rat brainstem-gastric preparation. gamma-Aminobutyric acid (GABA) subreceptor agonists and antagonists were applied to the gastric and brainstem compartments of the bath chamber to evaluate the peripheral gastric and central brainstem GABAergic effects on NTS neuronal activity. The gastric effects of the GABAA receptor agonist muscimol and GABAB receptor agonist baclofen were evaluated on 55 tonic units that received the gastric vagal inputs. For approximately 58% (32 of 55) and 38% (21 of 55) of the units observed, muscimol (30 microM; IC50 = 2.0 microM) and baclofen (30 microM; IC50 = 1.5 microM) in the gastric compartment induced a concentration-dependent inhibition of 36.2 +/- 3.1% (mean +/- S.E.) and 31.0 +/- 2.9% of the control level of the NTS neuronal activity, respectively. The brainstem effects of muscimol and baclofen were tested on 51 units. For approximately 90% (46 of 51) and 78% (40 of 51) of the units tested, muscimol (30 microM; IC50 = 1.3 microM) and baclofen (30 microM; IC50 = 1.1 microM) in the brainstem compartment produced a concentration-dependent inhibition of 54.1 +/- 3.4% and 48.9 +/- 3. 5% of the control level, respectively. The remaining NTS units were not affected by these two GABA agonists. Bicuculline (10 microM) and saclofen (10 microM), the GABAA and GABAB subreceptor antagonists, competitively antagonized the gastric and brainstem effects by muscimol and baclofen, respectively. Our results demonstrated that both GABAA and GABAB receptors in the stomach and brainstem play an important role in activity modulation of the medial NTS neurons receiving gastric vagal inputs in neonatal rats.

Animals↗

PubMed1997

Kappa and lambda rearrangement occur simultaneously in transformed pre-B cells.

Murine B-lineage cells can express either kappa or lambda Ig light chains. However, most of these cells express kappa protein, a phenomenon that appears to be controlled in part at the level of gene rearrangement. This feature may reflect a preference for the kappa locus by the recombinase machinery, or it may indicate that kappa rearrangement begins before lambda rearrangement. These possibilities can be distinguished by measuring the kinetics with which light chain gene rearrangement at both loci actually occurs. To this end, we have used pre-B cells transformed by temperature-sensitive mutants of Abelson virus that undergo kappa and lambda gene rearrangement when shifted to the nonpermissive temperature. Competitive PCR analyses of rearrangement kinetics demonstrate that the kappa and lambda loci rearrange at about the same time in these cells. Consistent with this, some clones isolated from cells induced for a short period of time have rearranged only the lambda locus. However, the frequency with which lambda genes are rearranged is three- to sixfold lower than that with which kappa genes rearrange. These data indicate that the recombinase machinery targets both light chain loci at the same time, but acts preferentially at the kappa locus. The reduced ability of the recombinase machinery to target the lambda locus and selection pressures occurring during B cell development probably both contribute to the preferential usage of kappa genes in normal murine B lineage cells.

3T3 Cells↗

PubMed1997

Isolated myocyte contractile function is normal in postinfarct remodeled rat heart with systolic dysfunction.

BACKGROUND: Postinfarction ventricular remodeling is associated with lengthening and contractile dysfunction of the remote noninfarcted myocardium. Mechanisms underlying this phenomenon remain unclear. METHODS AND RESULTS: We studied serial changes in global left ventricular (LV) structure and function in infarcted (1, 2, 4, and 6 weeks after myocardial infarction) and sham-operated rat hearts and correlated them with structural and functional changes in myocytes isolated from the remote LV myocardium in the same hearts. Rats with myocardial infarction developed significant remodeling. The heart weight-to-body weight ratios were increased. LV volumes at filling pressure of 10 mm Hg were higher (305+/-28 versus 215+/-12 microL, P<.01). This was accompanied by global LV dysfunction (in vivo LV end-diastolic pressure, 4+/-1 versus 23+/-1.6 mm Hg; Langendorff LV developed pressure, 105+/-4 versus 62+/-9 mm Hg, P<.001 for both). Myocytes isolated from these hearts showed significant structural remodeling (LV myocytes, 24% longer and 15% wider; right ventricular myocytes, 38% longer and 31% wider, all P<.05). LV myocyte length correlated with changes in LV volume (r=.79) and function (LV developed pressure, r=-.81). However, LV myocytes from the same hearts showed normal contractile function and intracellular Ca2+ transients at baseline and during inotropic stimulation with increasing extracellular Ca2+ (1 to 6 mmol/L). The shortening-frequency relationship was also similar in myocytes from sham and myocardial infarction rats. CONCLUSIONS: Postinfarct LV remodeling occurs predominantly by myocyte lengthening rather than by myocyte slippage. However, contractile function of the unloaded myocytes from the remote noninfarcted LV myocardium of the remodeled heart is normal. Therefore, myocyte contractile abnormalities may not contribute to global dysfunction of the remodeled heart. Reduced myocyte mass and nonmyocyte factors like increased wall stress, altered LV geometry, and changes in the myocardial interstitium may be more important in the genesis of postinfarct LV dysfunction in this model.

Animals↗

PubMed1997

Presence of distinct cis-acting elements on gonadotropin gene promoters in diverse species dictates the selective recruitment of different transcription factors by steroidogenic factor-1.

The nuclear receptor steroidogenic factor-1 (SF-1) regulates the cell-specific expression of the pituitary gonadotropin subunit genes. Several potential DNA-binding sites for SF-1, estrogen receptor (ER) and the immediate-early transcription factor NGFI-A are found in LHbeta genes from many species. In this study, we have examined the action and interaction of these transcription factors on LHbeta gene promoters from two representative vertebrate species, i.e. rat and salmon. Cotransfection studies in COS-1 cells have shown that the action of SF-1 on salmon gonadotropin IIbeta (sGTHIIbeta) gene promoter was dramatically enhanced when combined with ER. The rat LHbeta promoter was activated by SF-I or ER individually, but these two factors, however, were unable to act in synergism on this promoter. In contrast, NGFI-A, specifically in cooperation with SF-1, transactivated the rat LHbeta gene expression but was ineffective on the sGTHIIbeta gene. Gel shift experiments showed that this lack of activation was due to the low affinity of the salmon NGFI-A-responsive element for its binding protein. In conclusion, our studies demonstrate that differential recruitment of distinct transcription factors by SF-1 might be a common mechanism to activate the cell-specific gonadotropin gene expression in different species.

Animals↗

PubMed1997

Gene therapy.

In recent years, there have been a number of technological breakthroughs that have allowed for clinical trials in gene therapy to be initiated. In combination with the genome initiative, the potential for new therapeutics is limitless. Although an enormous amount of information has been obtained in a relatively short period of time, gene therapy is not yet ready for wide-scale practice. Some of the successes and obstacles that remain are summarized in this report.

Bone Marrow Diseases↗

PubMed1997

The relationship between the structures of the O polysaccharides from Escherichia coli O17 and O16.

The chemical structure of the O16 antigen from the lipopolysaccharide of Escherichia coli strain P4 has been determined. Comparison with the structures of other O16 antigens and that of the O17 antigen explains the previously reported cross-reaction of O antigen from the O16 strain K-12 with anti-O17 antibody [D. Liu and P.R. Reeves, Microbiology, 140 (1994) 49-57].

Carbohydrate Sequence↗

PubMed1997

Phorbol myristate acetate stimulates the dimerization of CD44 involving a cysteine in the transmembrane domain.

Receptor oligomerization is important for ligand binding and signal transduction. CD44 is a transmembrane protein present on many cell types. One of the ligands for CD44 is hyaluronic acid (HA). HA binding activity of CD44 is linked to cellular activation in some cell types. Clustering of CD44 has been speculated to be important for binding of HA. However, the molecular mechanisms for converting CD44 from an inactive receptor to an active receptor are not known. Here we report that PMA stimulates the binding of CD44 to HA by inducing clustering of CD44 followed by covalent homodimerization of CD44 on the cell surface. Covalent dimerization involves a cysteine (Cys286) in the transmembrane domain of CD44 and is essential for binding of high levels of fluorescein-conjugated HA. Activation-induced clustering followed by disulfide bond-mediated dimerization of CD44 represents an additional signal transduction mechanism for regulating receptor-ligand interactions.

Carcinogens↗

PubMed1997

Maternal care, hippocampal glucocorticoid receptors, and hypothalamic-pituitary-adrenal responses to stress.

Variations in maternal care affect the development of individual differences in neuroendocrine responses to stress in rats. As adults, the offspring of mothers that exhibited more licking and grooming of pups during the first 10 days of life showed reduced plasma adrenocorticotropic hormone and corticosterone responses to acute stress, increased hippocampal glucocorticoid receptor messenger RNA expression, enhanced glucocorticoid feedback sensitivity, and decreased levels of hypothalamic corticotropin-releasing hormone messenger RNA. Each measure was significantly correlated with the frequency of maternal licking and grooming (all r's > -0.6). These findings suggest that maternal behavior serves to "program" hypothalamic-pituitary-adrenal responses to stress in the offspring.

Adrenocorticotropic Hormone↗