Biomedical subjects

L Mou

Publications and source records attributed to L Mou.

14 recordsLinked to original sources

PubMed2001

Transient hypoxia differentially decreases GRK2 protein levels in CHO cells stably expressing the m1 mAChR.

G protein-coupled kinase 2 (GRK2) has a key role in regulating signaling activities of a variety of G protein-coupled receptors (GPCRs). Several recent studies have directly implicated GRK2 phosphorylation in desensitization of GPCRs. In addition, binding by G(betagamma) or phosphorylation by PKC or c-Src [corrected] has been shown to activate or enhance GRK2 activity, respectively. Conversely, the calcium binding protein calmodulin or the serine/threonine kinase ERK has been implicated in inhibiting GRK2 activity. However, with the exception of a recent report indicating that activation of beta2-adrenergic receptor results in the ubiquitination and rapid degradation of GRK2, very little is known about cellular mechanisms that alter the protein levels of GRK2 [corrected]. Here, we report a novel serendipitous observation regarding alteration of GRK2 [corrected] protein levels. Exposure of CHO cells stably expressing the m1 muscarinic acetylcholine receptor (mAChR) to transient hypoxia caused near ablation of the GRK2 protein. In contrast, GRK2 protein levels remained unchanged in the parental CHO cells or in CHO cells stably expressing the m2 mAChR when exposed to transient hypoxia. The present study reports a novel observation that is unveiled by transient hypoxia in which GRK2 protein levels are altered by cellular mechanisms involving the m1 mAChR.

Animals↗

PubMed2001

Hepatocyte growth factor is predominantly expressed by the carcinoma cells in non-small-cell lung cancer.

Hepatocyte growth factor (HGF) exerts multifunctional regulatory roles in the growth, morphogenesis, differentiation, and motility of epithelial cells, and putatively plays important roles in tumor angiogenesis and metastasis. Aside from the full-length protein, 2 naturally occurring truncated HGF isoforms (NK1 and NK2) have been identified. Recent evidence suggests that a high level of HGF in surgically resected non-small-cell lung carcinoma (NSCLC) is a negative prognostic marker for NSCLC patients' survival. The origin of HGF in these tumors remains uncertain. We show here by in situ hybridization and immunohistochemistry that HGF messenger RNA (mRNA) and protein were predominantly expressed by the tumor cells in a high percentage of primary NSCLC. Stromal cell expression of HGF was limited to some lymphocytes and endothelial cells. Normal bronchial and bronchiolar epithelial cells also expressed HGF mRNA and immunoreactive protein. The mRNA transcripts and putative proteins of all 3 known HGF isoforms were detected in both normal lung and lung cancer tissues, but the full-length HGF was predominantly expressed. Our findings indicate that both autocrine and paracrine functions of HGF are likely to contribute to the pathobiology of lung cancer in vivo.

Adenocarcinoma↗

PubMed2001

[Studies on non-protected fluid room temperature phosphorescence of phenanthrine].

A strong and stable room temperature phosphorescence (RTP) signal of phenanthrine aqueous solution in the absence of a protecting medium can be induced only by using Na2SO3 as deoxygenator and KI as heavy atom pertuber. The maximum phosphorescence intensity wavelengths are lambda ex/lambda em = 283/482,504 nm. It is also found that the kind and amount of organic solvent added to the luminescent system effects obviously the RTP properties. Under the present of 1% acetonitrile the RTP intensity is linear to phenanthrine concentration in the rage of 8.0 x 10(-7)-6.0 x 10(-6) mol.L-1 and 6.0 x 10(-6) mol.L(-1)-4.0 x 10(-5) mol.L-1, respectively. The detection limit is 2.6 x 10(-8) mol.L-1.

Acetonitriles↗

PubMed1999

[Synthesis and spectroscopic characterization of O,O,O',O'-tetramethyl-S,S'-(2-N,N-dimethylamino-trimethylene)-bis-phosphonodithionate oxalate].

A new organophosphorus insecticide, shacanlin, was synthesized by 1-dimethylamino-2,3-dichloropropane reacting on O,O-dimethyl-dithiophosphate and its oxalate was prepared. The molecular structure of shacanlin oxalate was characterized by 1H and 13C NMR spectrometry, IR and MS. The results indicate that the reaction product is 1,3-disubstituted product. The molecular structure of shacanlin oxalate is (CH3)2N+ HCH[CH2SP(S)(OCH3)2]2 x C2O4H-[O,O,O',O'-tetramethyl-S,S'-(2-N,N-dimethylamino-trimethylene)-bis phosphonodithionate oxalate].

Magnetic Resonance Spectroscopy↗

PubMed1999

[Study on properties of fluorescence and room temperature phosphorescence of 2-bromomethyl naphthalene].

The properties of fluorescence and room temperature phosphorescense (RTP) of 2-Bromomethyl naphthalene (2-BrMN)were studied. The results show that the wavelength for maximum fluorescence of 2-BrMN is lambda(ex/lambda(em) = 274/334 nm. The fluorescence intersity is proportional to the concentration of 2BrMN in the range of 1.0 x 10(-6) - 1.2 x 10(-4) mol x L(-1), and the detection limit is 4.7 x 10(-8) mol x L(-1). The RTP signal of 2-BrMN was induced by beta-cyclodextrin (beta-(CD) in the presence of dibromopropane (DBP) acting as a heavy atom perturbation. The RTP intensity is linear for 2-BrMN/beta-CD/DBP systems of 2-BrMN concentration in the range of 1.0 x 10(-5) - 1.2 x 10(-4) mol x L(-1) (lambda(ex)/lambda(em) = 271/493,521 nm), and the detection limit is 2.7 x 10(-6) mol x L(-1).

English Abstract↗

PubMed1998

[Cyclodextrin induced-room temperature phosphorescence for the determination of quinoline without deoxidization].

A cyclodextrininduced-room temperature phosphorescence (CD-RTP) system for the determination of quinoline without deoxidization procedure was developed based on the external heavy atom effect of dibromopropane (DBP), the RTP maximum wavelengths lambda(ex)/lambda(em) = 273/496nm. The difference of heavy atom effect between dibromopropane DBP and dibromoethane (DBE) was examined and the apparent formation constants of the ternary inclusion complexes for quinoline/beta-CD/DBP and quinoline/beta-CD/DBE systems were determined. As compared with DBE, the heavy atom effect of DBP was higher and the RTP intensity was stronger. The RTP intensity was linear for quinoline/beta-CD/DBP systems with quinoline concentration in the ranges of 5.0 x 10(-7)-5.0 x 10(-5)mol/L and 5.0 x 10(-5)-5.0 x 10(-4)mol/L, respectively. The detection limit was 7.8 x 10(-8)mol/L. The determination precision was satisfactory.

Calibration↗

PubMed1997

[Fluorometric determination of trace Shachongdan with calcein-Pd2+].

A fluorometric determination of trace Shachongdan (SCD) [(CH3)2NHCH (CH2S2O3- )CH2S2O3Na x H2O] is described. The method is based on the calcein display fluorescence in pH6-7 phosphate buffer solution, it react with Pd2+ to the fluorescence disappeared. The complex of SCD-Pd2+ is more stability than the complex of calcein-Pd2+, when SCD react with calcein -PdZ+, the calcein can be freed and its fluorescence appears once again. The fluorescence excitation and emission wavelenghts are 494 and 514nm. The linear range is 2 x 10(-7) mol/L-3 x 10(-6)mol/L and the detection limit is 6 x 10(-8)mol/L.

Fluoresceins↗

PubMed1996

Localization and down-regulating role of the protein tyrosine phosphatase PTP2C in membrane ruffles of PDGF-stimulated cells.

PTP2C (also known as Syp/SH-PTP2/PTPlD) is a soluble protein tyrosine phosphatase present in most cell types. It interacts directly with activated PDGF receptor via its SH2 domains, which results in its phosphorylation on tyrosine residue(s). The phosphorylated PTP2C in turn binds to the SH2 domain of GRB2, serving as an adaptor in the transduction of mitogenic signals from the growth factor receptor to the Ras and MAP kinase signaling pathways. We investigated the interaction of PTP2C with the PDGF receptor by examining the localization of both proteins after PDGF stimulation of 293 cells which stably express the human PDGF receptor. In resting cells, transiently expressed PTP2C was distributed throughout the cytoplasm. Upon stimulation with PDGF, PTP2C was translocated from the cytoplasm to membrane ruffles. Immunofluorescence examination revealed that PTP2C colocalized with actin, the PDGF receptors, and hyper-tyrosine- phosphorylated protein(s). Neither deletion of the SH2 domains nor point mutations at either the catalytic site or the major phosphorylation site affected membrane ruffling or the localization of PTP2C to the ruffles of PDGF-stimulated cells. However, the expression of a catalytically inactive mutant PTP2C substantially prolonged ruffling activity following PDGF stimulation. These results suggest that PTP2C is involved in the down-regulation of the membrane ruffling pathway, and in contrast to its positive function in the MAP kinase pathway, the phosphatase activity negatively regulates ruffling activity.

Adaptor Proteins, Signal Transducing↗

PubMed1995

Presence of an additional PstI fragment in intron 1 of the chicken growth hormone-encoding gene.

A previously unreported 196-bp PstI fragment was found in intron 1 of the gene encoding chicken growth hormone (cGH) when a PCR assay for an MspI restriction fragment length polymorphism was established. A pair of PCR primers was designed according to the published cGH sequence and used to amplify a fragment which contained two MspI sites, one polymorphic and another non-polymorphic. However, amplification of genomic DNA from two strains of meat-type chickens and three strains of White Leghorn chickens yielded a PCR product which was about 200 bp larger than expected. The fragment from one of the meat-type chickens was subcloned into the vector pCR-Script SK+, and sequenced. It revealed the presence of an extra fragment of 196 bp which was flanked by the PstI sites and occurred at nt +308 of the previously reported cGH sequence.

Animals↗

PubMed1994

Improvements to the differential display method for gene analysis.

Differential display requires two primers to identify discordantly expressed mRNAs. Anchored primers with at least one G residue were superior to those which had one C residue and those ending in A or T were the least efficient. Arbitrary primers with GC pairs at the 5'end were superior to primers with GC pairs at the 3'end. We found that screening of amplified DNA-fixed membranes by a slot blot manifold and hybridization with DNA probes made from sample RNA rapidly re-screened with DNA fragments for differential expression, requires less RNA and is faster than Northern analysis. Similarly, hybridization of DNA fragments to plasmid DNA fixed to membranes and direct PCR sequencing rapidly determine homology to common laboratory plasmids prior to any further manipulation. These modifications permit rapid isolation and characterization of DNA fragments identified by differential display.

Animals↗

PubMed1993

Synergism between the endogenous viral loci ev6 and ev9 in inducing immunological tolerance to avian leukosis virus.

1. The course of infection by exogenous avian leukosis virus was followed in a commercial strain of White Leghorn domestic fowls by measuring viral antigen in feather pulp and egg albumin. Ten days after hatching, 2 out of 360 birds tested positive and at 286 days of age about 60% of the birds had been antigen positive at least once. 2. Among the antigen positive birds, two groups could be distinguished: those which permanently and those which transiently expressed viral antigen. Permanent antigen expression was associated with low antibody titres, while transient antigen expression was associated with high antibody titres. 3. The strain segregated for the two endogenous viral genes ev6 and ev9, both of which express endogenous viral envelope protein, and have been implicated in affecting immune-responsiveness. The antibody titre in individuals positive for both ev6 and ev9, was significantly lower than in those which had none or only one of the two ev-genes. In addition, individuals positive for both ev-genes occurred more frequently in the group permanently positive for viral antigen than in the group transiently antigen positive. 4. The results indicate that there was a strong synergism between ev6 and ev9 in reducing the antibody response to exogenous avian leukosis virus infection, perhaps by inducing immune tolerance or interfering with antibody formation.

Animals↗

PubMed1976

Autolysis of Streptococcus cremoris.

The autolysin of Streptococcus cremoris had the specificity of an endo-N-acetylmuramidase as it hydrolysed the linkage between N-acetylmuramic acid and N-acetylglucosamine. The enzyme had no amidase or endopeptidase action. It reached highest activity in the exponential phase of growth and in the electron microscope seemed to fragment the coccal wall at the equatorial ring.

Amidohydrolases↗

PubMed1975

Pptidase activities in group N streptococci.

Several peptidase activites in the 3 species of Group N streptococci were partly separated by gel filtration on Sephadex G-200. The peptidases identified were a general aminopeptidase of wide specificity, a tripeptidase, a proline iminopeptidase (prolyl-beta-napthylamidase), a proline iminodipeptidase and an aminopeptidase-P. The effects of temperature and pH on the stability of the enzyme activities, and the influence of the type of N source used in the growth medium on the elution pattern of the enzymes were examined.

Aminopeptidases↗

PubMed1972

Purification and properties of nicotinamide adenine dinucleotide-dependent D- and L- lactate dehydrogenases in a group N streptococcus.

Streptococcus lactis strain 760, a group N streptococcus, was found to possess nicotinamide adenine dinucleotide-dependent dehydrogenase activities for both the l(+) and the d(-) isomers of lactic acid. The two enzymes were isolated and purified and were found to differ with respect to pH optima, activation by fructose-1,6-diphosphate, pH and heat stability, and the temperature at which each enzyme was formed in the organism during growth. The presence of a racemase for lactic acid was not detected by the methods used.

Ammonium Sulfate↗