Differential modulation of GABAA receptor function by Mel1a and Mel1b receptors.
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Animals↗
Biomedical subjects
F Liu
Publications and source records attributed to F Liu.
Hydrodynamics-based transfection in animals by systemic administration of plasmid DNA.
Development of methods that allow an efficient expression of exogenous genes in animals would provide tools for gene function studies, treatment of diseases and for obtaining gene products. Therefore, we have developed a hydrodynamics-based procedure for expressing transgenes in mice by systemic administration of plasmid DNA. Using cDNA of luciferase and beta-galactosidase as a reporter gene, we demonstrated that an efficient gene transfer and expression can be achieved by a rapid injection of a large volume of DNA solution into animals via the tail vein. Among the organs expressing the transgene, the liver showed the highest level of gene expression. As high as 45 microg of luciferase protein per gram of liver can be achi- eved by a single tail vein injection of 5 microg of plasmid DNA into a mouse. Histochemical analysis using beta-galactosidase gene as a reporter reveals that approximately 40percent of hepatocytes express the transgene. The time-response curve shows that the level of transgene expression in the liver reaches the peak level in approximately 8 h after injection and decreases thereafter. The peak level of gene expression can be regained by repeated injection of plasmid DNA. These results suggest that a simple, convenient and efficient method has been developed and which can be used as an effective means for studying gene function, gene regulation and molecular pathophysiology through gene transfer, as well as for expressing proteins in animals.
Animals↗
New signs characteristic of myocardial bridging demonstrated by intracoronary ultrasound and Doppler.
BACKGROUND: Large discrepancies exist concerning the incidence of myocardial bridging. This has been reported to be 0.5%-2.5% following coronary angiography but 15%-85% following autopsy. The purpose of the study was to use intravascular ultrasound and intracoronary Doppler to study the morphology and flow characteristics of myocardial bridging in order to find feasible parameters of this syndrome. METHODS AND RESULTS: Intravascular ultrasound was performed in 62/69 patients in whom typical angiographic 'milking effects' were present. In 48 patients, intracoronary Doppler was performed. A specific, echolucent 'half moon' phenomenon surrounding the myocardial bridge was found in all the patients. The thickness of the half moon area was 0.47 +/- 0.19 mm in diastole and 0.52 +/- 0.23 mm in systole. There was systolic compression of the myocardial bridge with a lumen reduction during systole of 36.4 +/- 8.8%. Using intracoronary Doppler, a characteristic early diastolic 'finger tip' phenomenon was observed in 42 (87%) of the patients. All patients showed no or reduced antegrade systolic flow. Coronary flow velocity reserve was 2.03 +/- 0. 54. After intracoronary nitroglycerin injection, retrograde systolic flow occurred in 37 (77%) of the 48 patients, with a velocity of -22. 2 +/- 13.2 cm. s(-1). Intravascular ultrasound revealed atherosclerotic involvement of the proximal segment in 61 (88%) of the 69 patients, with an area stenosis of 42 +/- 13%. No plaques were found in the bridge or distal segments in the 62 patients in whom it was possible to introduce the ultrasound catheter throughout the bridging segment. CONCLUSION: Myocardial bridging is characterized by the following morphological and functional signs: a specific, echolucent half moon phenomenon over the bridge segment, which exists throughout the cardiac cycle; systolic compression of the bridge segment of the coronary artery; accelerated flow velocity at early diastole (finger-tip phenomenon); no or reduced systolic antegrade flow; decreased diastolic/systolic velocity ratio; retrograde flow in the proximal segment, which is provoked and enhanced by nitroglycerin injection.
Blood Flow Velocity↗
Preparation and characterization of monoclonal antibodies against GAM protein: a novel gp130-associated molecule.
gp130-associated-molecule (GAM) is a recently cloned 24-kDa protein, which binds to gp130 at its cytoplasmic membrane-proximal region and has high homology with the N-terminal of Groucho/TLE molecules, a transcription co-repressor family playing an essential role in Notch signaling. Expression of GAM in COS7 cells inhibited the association of JAKs with gp130, and decreased the tyrosine phosphorylation level of these molecules as well. To further investigate the function of GAM, monoclonal antibodies (MAbs) to GAM were prepared. First, GAM-Thioredoxin(Thio) fusion protein was expressed in E. coli and purified with anti-Thio PAb coupled Sepharose-4B. Using purified GAM-Thio as immunogen, three MAbs against GAM with high affinity were raised by conventional B-lymphocyte hybridoma technique. They could recognize different epitopes of nature and denatured GAM-Thio without any cross-reaction with Thio or components of E. coli or with TLE1-GST fusion protein. In Western blotting and flow cytometric assay, these MAbs can detect cellular GAM protein and verify the increase of GAM expressing in GAM cDNA permanently transfected M1 cells. Furthermore, Western blotting with these MAbs indicated that GAM formed 110 kDa polymers in the nucleus. These MAbs represent powerful in investigating the role of GAM in gp130 signaling and Notch signaling.
Animals↗
The effect of mating system differences on nucleotide diversity at the phosphoglucose isomerase locus in the plant genus Leavenworthia.
To test the theoretical prediction that highly inbreeding populations should have low neutral genetic diversity relative to closely related outcrossing populations, we sequenced portions of the cytosolic phosphoglucose isomerase (PgiC) gene in the plant genus Leavenworthia, which includes both self-incompatible and inbreeding taxa. On the basis of sequences of intron 12 of this gene, the expected low diversity was seen in both populations of the selfers Leavenworthia uniflora and L. torulosa and in three highly inbreeding populations of L. crassa, while high diversity was found in self-incompatible L. stylosa, and moderate diversity in L. crassa populations with partial or complete self-incompatibility. In L. stylosa, the nucleotide diversity was strongly structured into three haplotypic classes, differing by several insertion/deletion sequences, with linkage disequilibrium between sequences of the three types in intron 12, but not in the adjacent regions. Differences between the three kinds of haplotypes are larger than between sequences of this gene region from different species. The haplotype divergence suggests the presence of a balanced polymorphism at this locus, possibly predating the split between L. stylosa and its two inbreeding sister taxa, L. uniflora and L. torulosa. It is therefore difficult to distinguish between different potential causes of the much lower sequence diversity at this locus in inbreeding than outcrossing populations. Selective sweeps during the evolution of these populations are possible, or background selection, or merely loss of a balanced polymorphism maintained by overdominance in the populations that evolved high selfing rates.
Base Sequence↗
Dithiothreitol enhances arsenic trioxide-induced apoptosis in NB4 cells.
Recently, arsenic trioxide (As2O3) was reported to induce clinical remission in patients with acute promyelocytic leukemia. Modulation of protein phosphorylation by binding to the vicinal thiols has been suggested as a possible mechanism. We found that phenylarsine oxide, a strong vicinal thiol-binding agent, neither induced nuclear fragmentation or DNA laddering nor increased caspase activity in NB4 cells; however, As2O3 and a weak thiol-binding agent, dimethylarsinic acid, did increase activity. Dithiothreitol (DTT) effectively suppressed the phenylarsine oxide-inhibited cellular reductive capacity, but unexpectedly, enhanced As2O3-induced apoptosis in NB4 cells. As2O3-induced and As2O3-plus-DTT-induced apoptosis in NB4 cells was modulated by oxidant modifiers, but not by nitric oxide synthase inhibitors. These results demonstrate that DTT, a dithiol agent and known antidote for trivalent inorganic arsenic, enhances the toxicity of As2O3, thereby opening a new research direction for the mechanisms of arsenic toxicity and perhaps also helping in the development of new therapeutic strategies for treating leukemias.
Apoptosis↗
Overproduction of human Myt1 kinase induces a G2 cell cycle delay by interfering with the intracellular trafficking of Cdc2-cyclin B1 complexes.
The Myt1 protein kinase functions to negatively regulate Cdc2-cyclin B complexes by phosphorylating Cdc2 on threonine 14 and tyrosine 15. Throughout interphase, human Myt1 localizes to the endoplasmic reticulum and Golgi complex, whereas Cdc2-cyclin B1 complexes shuttle between the nucleus and the cytoplasm. Here we report that overproduction of either kinase-active or kinase-inactive forms of Myt1 blocked the nuclear-cytoplasmic shuttling of cyclin B1 and caused cells to delay in the G2 phase of the cell cycle. The COOH-terminal 63 amino acids of Myt1 were identified as a Cdc2-cyclin B1 interaction domain. Myt1 mutants lacking this domain no longer bound cyclin B1 and did not efficiently phosphorylate Cdc2-cyclin B1 complexes in vitro. In addition, cells overproducing mutant forms of Myt1 lacking the interaction domain exhibited normal trafficking of cyclin B1 and unperturbed cell cycle progression. These results suggest that the docking of Cdc2-cyclin B1 complexes to the COOH terminus of Myt1 facilitates the phosphorylation of Cdc2 by Myt1 and that overproduction of Myt1 perturbs cell cycle progression by sequestering Cdc2-cyclin B1 complexes in the cytoplasm.
Binding Sites↗
Inhibitory effect of oestradiol on activation of rat hepatic stellate cells in vivo and in vitro.
BACKGROUND: Hepatic stellate cells play a key role in the pathogenesis of hepatic fibrosis. AIMS: To examine the inhibitory effect of oestradiol on stellate cell activation. METHODS: In vivo, hepatic fibrosis was induced in rats by dimethylnitrosamine or pig serum. In vitro, rat stellate cells were activated by contact with plastic dishes resulting in their transformation into myofibroblast-like cells. RESULTS: In the dimethylnitrosamine and pig serum models, treatment with oestradiol at gestation related doses resulted in a dose dependent suppression of hepatic fibrosis with restored content of hepatic retinyl palmitate, reduced collagen content, lower areas of stellate cells which express alpha smooth muscle actin (alpha-SMA) and desmin, and lower procollagen type I and III mRNA levels in the liver. In cultured stellate cells, oestradiol inhibited type I collagen production, alpha-SMA expression, and cell proliferation. These findings suggest that oestradiol is a potent inhibitor of stellate cell transformation. CONCLUSION: The antifibrogenic role of oestradiol in the liver may contribute to the sex associated differences in the progression from hepatic fibrosis to cirrhosis
Animals↗
Gialpha but not gqalpha is linked to activation of p21(ras) in human airway smooth muscle cells.
Airway smooth muscle hypertrophy contributes to the narrowing of asthmatic airways. Activation of the mitogen-activated protein kinases is an important event in mediating cell proliferation. Because the monomeric G protein p21(ras) is an important intermediate leading to activation of mitogen-activated protein kinases, we questioned which heterotrimeric G protein-coupled receptors were linked to the activation of p21(ras) in cultured human airway smooth muscle and which of the heterotrimeric G protein subunits (alpha or betagamma) transmitted the activation signal. Carbachol and endothelin-1 increased GTP-bound p21(ras) in a pertussis toxin-sensitive manner [ratio of [32P]GTP to ([32P]GTP + [32P]GDP): control, 30 +/- 1.7; 3 min of 1 microM carbachol, 39 +/- 1.1; 3 min of 1 microM endothelin-1, 40 +/- 1.2], whereas histamine, bradykinin, and KCl were without effect. Transfection of an inhibitor of the G protein betagamma-subunit [the carboxy terminus (Gly495-Leu689) of the beta-adrenoceptor kinase 1] failed to inhibit the carbachol-induced activation of p21(ras). These data suggest that Gi- but not Gq-coupled receptors activate p21(ras) in human airway smooth muscle cells, and this effect most likely involves the alpha-subunit.
Bradykinin↗
Endothelial nitric oxide gene knockout mice: cardiac phenotypes and the effect of angiotensin-converting enzyme inhibitor on myocardial ischemia/reperfusion injury.
We tested the hypothesis that nitric oxide (NO) released by endothelial NO synthase (eNOS) is not only important in blood pressure regulation but also involved in cardiac function and remodeling and in the cardioprotective effect of angiotensin-converting enzyme inhibitors (ACEi). With the use of a 2D Doppler echocardiography system equipped with a 15-MHz linear transducer, we evaluated left ventricular (LV) morphology and function in conscious eNOS knockout mice (eNOS(-/-); n=15) and their wild-type littermates (eNOS(+/+); n=16). We also studied whether in eNOS(-/-) mice (1) myocardial ischemia/reperfusion injury is more severe and (2) the cardioprotective effect of ACEi is diminished or absent. In comparison with the wild type, eNOS(-/-) mice had significantly increased systolic blood pressure (128+/-3 versus 108+/-5 mm Hg; P<0.001) and decreased heart rate (531+/-22 versus 629+/-18 bpm; P<0.001) associated with increased LV posterior wall thickness (0.80+/-0.04 versus 0.64+/-0.02 mm; P<0.001) and LV mass (18.3+/-0.9 versus 13.1+/-0.5 mg/10 g body weight; P<0.01). Despite hypertension and LV hypertrophy, LV chamber dimension, shortening fraction and ejection fraction (indicators of LV contractility), and cardiac output did not differ between the 2 strains, which indicates that LV function in eNOS(-/-) mice is well compensated. We also found that in eNOS(+/+) mice, ACEi decreased the ratio of myocardial infarct size to area at risk from 62.7+/-3.9% to 36.3+/-1.6% (P<0. 001), whereas in eNOS(-/-) mice this effect of ACEi was almost abolished: the ratio of myocardial infarct size to area at risk was 67.2+/-2.9% in the vehicle-treated group and 62.7+/-3.9% in mice treated with ACEi. Moreover, infarct size in vehicle-treated eNOS(-/-) mice was not significantly different from eNOS(+/+) mice given the same treatment. We concluded that (1) endothelium-derived NO plays an important role in the regulation of blood pressure homeostasis; (2) NO released under basal conditions has no significant impact on cardiac function; and (3) ACEi protect the heart against ischemia/reperfusion injury in mice and that this effect is mediated in part by endothelium-derived NO.
Angiotensin-Converting Enzyme Inhibitors↗
Effect of molecular weight and polydispersity on kinetics of dissolution and release from ph/temperature-sensitive polymers.
N-isopropylacrylamide (NIPAAm) polymers exhibit a lower critical solution temperature (LCST). Aqueous solutions of these polymers are soluble below their LCST and precipitate above their LCST. The LCST is dependent on pH for polymers with ionizable groups because of a change in hydrophilicity with ionization and electrostatic repulsion that cause a shift in the LCST. We have designed a novel polymeric delivery system that utilizes linear, pH/temperature-sensitive terpolymers of NIPAAm, butyl methacrylate (BMA) and acrylic acid (AA). This system allows the aqueous loading of drugs in polymeric beads with high loading efficiency while preserving the bioactivity of the protein drug. Furthermore, the unique properties of the pH/temperature-sensitive polymeric bead make it a potential system for oral drug delivery of peptide and protein drugs to different regions of the intestinal tract. This study aims at investigating the effect of polydispersity and molecular weight (MW) of terpolymers of poly(NIPAAm-co-BMA-co-AA) with feed mol ratio of NIPAAm/BMA/AA 85/5/10 on the polymer dissolution rate and on the release kinetics of a model protein, namely insulin. Varying the weight average MW (Mw) and polydispersity of the polymer modulated the polymer dissolution rate and the release rate of insulin from pH/temperature-sensitive polymeric beads. An increase in the polydispersity of the polymer through the addition of high MW polymer chains caused a decrease in the release rate of insulin and in the polymer dissolution rate. High MW polymer chains impose a certain degree of interaction between polymer chains due to chain entanglement. There is a limiting value of MW above which chain entanglement has no effect on drug release rate.
Acrylamides↗
A functional granulocyte colony-stimulating factor receptor is required for normal chemoattractant-induced neutrophil activation.
Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor that is widely used to treat neutropenia. In addition to stimulating polymorphonuclear neutrophil (PMN) production, G-CSF may have significant effects on PMN function. Because G-CSF receptor (G-CSFR)-deficient mice do not have the expected neutrophilia after administration of human interleukin-8 (IL-8), we examined the effect of the loss of G-CSFR on IL-8-stimulated PMN function. Compared with wild-type PMNs, PMNs isolated from G-CSFR-deficient mice demonstrated markedly decreased chemotaxis to IL-8. PMN emigration into the skin of G-CSFR-deficient mice in response to IL-8 was also impaired. Significant chemotaxis defects were also seen in response to N-formyl-methionyl-leucyl-phenylalanine, zymosan-activated serum, or macrophage inflammatory protein-2. The defective chemotactic response to IL-8 does not appear to be due to impaired chemoattractant receptor function, as the number of IL-8 receptors and chemoattractant-induced calcium influx, actin polymerization, and release of gelatinase B were comparable to those of wild-type PMNs. Chemoattractant-induced adhesion of G-CSFR-deficient PMNs was significantly impaired, suggesting a defect in beta2-integrin activation. Collectively, these data demonstrate that selective defects in PMN activation are present in G-CSFR-deficient mice and indicate that G-CSF plays an important role in regulating PMN chemokine responsiveness.
Actins↗
Differential diagnosis of monoclonal gammopathies.
Several disorders are associated with a monoclonal immunoglobulin detected by serum or urine electrophoresis, the most common being a monoclonal gammopathy of undetermined significance, multiple myeloma, Waldenstrom's macroglobulinemia, and amyloidosis. The clinical features of these conditions, as well as other similar entities, are described in this review. The objective is to demonstrate the importance of electrophoretic studies in the differential diagnosis of plasma cell dyscrasias and in guiding the decision for rational therapies.
Diagnosis, Differential↗
[The effect of serum TGFb1 of patients with chronic hepatitis B in liver fibrosis formation].
OBJECTIVES: To observe the relation between serum transforming growth factor beta 1(TGF beta 1) and level of PCIII, LN, HA, proliferation of hepatic fibrotic tissue. METHODS: Serum TGF beta 1 was detected by ELISA in 58 patients with chronic hepatitis B(CHB) and 18 patients with liver cirrhosis(LC). 20 healthy persons served as normal control(NC). Liver puncture was performed in 29 patients with CHB. Diagnosis of pathological histology and quantitative analysis of collagenous and reticular fibers were made. RESULTS: (1)Serum TGF beta 1 levels in CHB and LC were notably higher than in NC (P < 0.01) and increased successively in mild, moderate and severe degrees of CHB and LC(P < 0.01/0.05). (2)Serum TGF beta 1 was correlated with serum levels of PCIII, LN, HA(P < 0.01/0.05)positively. The quantity of hepatic collagenous and reticular fibers went up in mild, moderate and severe degrees of CHB(P < 0.01/0.05). Meanwhile serum TGF beta 1 rose at the same degree. CONCLUSION: Serum TGF beta 1 levels increase in CHB and LC. With hepatic pathological change worsening, serum TGF beta 1 and the quantity of hepatic collagenous and reticular fibers increased to the same degree. This suggests that TGF beta 1 is a crucial factor in accelerating liver fibrosis and plays a decisive role in liver fibrosis.
Adult↗
[The medialis pedis flap based on the medial fasciocutaneous branches of the dorsal pedal artery].
OBJECTIVE: This is to report the design and application of the medialis pedis flap. METHODS: Based on the medial fasciocutaneous branches of the dorsal pedal artery, a medialis pedis flap can be raised. The flap had been used in 18 patients with soft tissue defects of the dorsum pedis, ankle region, lower leg or hand. RESULTS: The anatomic observation of the blood supply to the medial region of the foot showed that a constant distribution of fasciocutaneous branches issued from the dorsal pedal artery was an important blood supply to this area. All flaps used in the 18 patients survived completely with satisfactory results and minimal morbidity at the donor site. CONCLUSION: We believe that the medial fasciocutaneous branches of the dorsal pedal artery are the reliable pedicle of the medialis pedis flap. The flap is useful for reconstruction of the soft tissue defects around the foot, ankle, lower leg or hand.
Adolescent↗
[Pathological changes of intracranial arteries in cerebral infarction].
OBJECTIVE: To investigate the cause and severity of intracranial arterial lesions in extensive cerebral infarction (CI). METHODS: 78 consecutive autopsy cases were studied. They included 58 cases of CI and 20 cases of other diseases as control. Medium-sized intracranial arteries and their main branches, small intracerebral arteries, and arterioles were examined with light microscopy. Quantitative analysis was made with computer. RESULTS: CI due to embolism was seen in 33/58 (56.9%) cases, thrombosis in 11/58 (19%), and unknown etiology in 14/58 (24.1%). The mean LA-VA ratios of the medium-sized intracranial arteries and their main branches, small intracerebral arteries and arterioles were lower in the CI patients than in the controls (P < 0.01). Atherosclerotic narrowing of the distal part of M1 segment of both lateral cerebral middle arteries, the basilar arteries and the main branches in the patients with thrombosis was markedly more severe than in those with embolism (P < 0.05, P < 0.01). CONCLUSION: Patients with CI have arterial lesions of different levels but the principal portions of cerebral artery lesions are the medium-sized intracranial arteries and their main branches. Thrombosis and embolism with medium, severe atherosclerotic narrowing of several arteries may play an important role in causing extensive CI in the middle aged and the elderly.
Aged↗
[The proper opportunity of surgery for rectal cancer after preoperative adjuvant chemotherapy].
OBJECTIVE: To discuss the proper opportunity of surgery for rectal cancer after preoperative intra-arterial chemotherapy. METHODS: Preoperative chemotherapy was performed on 27 rectal cancer cases at Dukes stage B and C. The therapy comprised of arterial infusion of 5-fluorouracil 600 mg/m(2), mitomycin 15 mg/m(2) and epirubicin 30 mg/m(2) for one course. Miles' or Dixon's operation was carried out 7 to 10 days later. The effects of chemotherapy were evaluated. Dynamic changes of proliferating cell nuclear antigen (PCNA) expression were studied by immunohistochemistry on paraffin-embedded sections. RESULTS: Hematochezia was remitted in 19 cases. Histologically, the effects of chemotherapy were considered as slight, moderate and marked in 9, 15 and 3 cases, respectively. Side effects were slight and recovered in 4 days. There was a high expression of PCNA in rectal cancer. On the 7th to the 10th day, proliferating index was significantly higher than that of before chemotherapy (46.48 +/- 10.62)%, P < 0.05. CONCLUSIONS: Preoperative adjuvant chemotherapy plays a role in the treatment of resectable rectal cancer. It is suggested that radical surgery should be carried out 5 to 6 days after intra-arterial chemotherapy.
Adult↗
[Timing changes of apoptosis and proliferating cells nuclear antigen after intra-arterial infusion chemotherapy for rectal cancer].
OBJECTIVE: To investigate the timing changes of apoptosis (APO) and PCNA after intra-arterial infusion chemotherapy for rectal cancer. METHODS: Twelve patients were subjected to percutaneous arterial femoralis catheterization by Seldinger's technique and infusion of anti-cancer drugs: 5-fluorouracil (5-Fu) 600 mg/m(2), mitomycin (MMC) C5 mg/m(2) and epirubicin (EDR) 35 mg/m(2). The biopsy of rectal tumor tissues was done before chemotherapy, and 24, 48, 72 hours and 7-10 days after chemotherapy. Apoptotic cells were examined by terminal-deoxynucleotidyl-transferase (TdT)-mediated dUTP-fluorescein and labeling. The expression of proliferating cells nuclear antigen (PCNA) was detected by immunohistologic staining. RESULTS: The apoptosis index (AI) of rectal cancer cells before chemotherapy, and 24, 48, 72 hours, and 7-10 days after chemotherapy was 6.84 per thousand, 19.53 per thousand, 13.15 per thousand, 11.85 per thousand and 11.86 per thousand respectively. The PCNA index (PI) was 45.56%, 40.68%, 39. 87%, 51.28% and 63.75% before and 24, 48, 72 hours, and 7-10 days after chemotherapy. CONCLUSIONS: Intra-arterial infusion chemotherapy not only induced apoptosis effectively, but also inhibited temporarily tumor cells proliferation in patients. The curative surgical treatment should be performed as soon as possible after chemotherapy.
Adult↗