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Biomedical subjects

W Luo

Publications and source records attributed to W Luo.

At least 91 records · Page 5Linked to original sources
PubMed1999

Effects of BRL 55 834 on allergen-induced bronchoconstriction and airway inflammation in sensitized guinea pigs.

OBJECTIVE: To investigate the effects of potassium channel activator on allergen-induced bronchoconstriction and airway inflammation and to discuss which role it plays in asthma therapy. METHODS: Airway insufflation pressure, examination of inflammatory cells in bronchial alveolar lavage fluid, analysis of airway pathology and airway Evans blue dye extravasation measurement were employed to detect airway resistance and airway inflammatory responses. RESULTS: [(3s, 4R)-3, 4-dihydro-2, 2-dimethyl-4-(2-oxopiperidin-l-yl)-6-pentafluoroethyl-2H-1-benzopyran-3-ol] (BRL) 55 834 (8 micrograms/kg) inhibited not only ovalbumin-induced airway insufflation pressure increase but also inflammatory cell infiltration (ICI) in sensitized guinea-pigs; moreover, it did not decrease blood pressure; in contrast to BRL 55 834, single dose of BRL 38 227 (200 micrograms/kg) and verapamil (0.5 mg/kg) had a little effect on ICI; single dose of aminophylline (25 mg/kg) and dexamethasone (1 mg/kg) could not inhibit ICI, but the former could inhibit airway insufflation increase; drugs, besides aminophylline, could reduce microvascular leakage; single dose of BRL 38 227, verapamil and dexamethasone had no inhibition of airway insufflation pressure; BRL 38 227 and verapamil decreased blood pressure markedly. CONCLUSIONS: Selective potassium channel activator BRL 55 834 not only decreases airway resistance, but also inhibit airway inflammation, and both of them are of benefit to asthma therapy.

Animals↗
PubMed1999

[Laboratory and clinical investigation on lower respiratory tract infection by Haemophilus influenzae].

OBJECTIVE: To improve the positive rate of Hi isolation and to study the epidemiology, antibiotic sensitivity and clinical characteristics of the lower respiratory tract infection by Hi. METHODS: Modified Columbia chocolate agar(ICCA) was compared with blood agar staphy stick (BASS) for the primary isolation of Hi from sputa. The sensitivities of 20 antibiotics to Hi were determined in vitro by KB method and MICs of 12 antibiotics were determined by broth microdilution method. The clinical characteristics of 92 cases with lower respiratory tract infection by Hi were analyzed. RESULTS: The isolation rate of Hi by ICCA was 20%, which was higher than 13% of BASS(P < 0.01). The third generation cephalosporins and the quinolones were most active against Hi. The resistant rate against Hi of ampicillin was 21%, however, that of the third generation cephalosporins was 45%-49%. 67(73%) of 92 cases were bronchopneumonia. CONCLUSIONS: The isolation rate of Hi could be improved by ICCA. The clinical characteristic of lower respiratory tract infection by Hi was not specific. There has been a steady increase of antibiotic resistance during these years.

Adolescent↗
PubMed1999

[Study on serotyping of Haemophilus influenzae and the positive rates of beta-lactamase].

OBJECTIVE: To investigate the serotypes of both infectious and carriage strains of Haemophilus influenzae (Hi) and to evaluate the prevalence of beta-lactamase of major serotypes in Shanghai. METHODS: The 534 specimens of sputum and swabs from patients with acute upper or lower respiratory tract infection and 255 cases of control group were collected and incubated on improved Collumbia chocolate medium. All isolated Haemophilus influenzae strains were serotyped by slide agglutinating assay or reverse indirect blood agglutinating method. beta-lactamase were measured by iodine test and paper disc method. RESULTS: In the patient group, of the 164 Hi strains there were 69 Hib strains (42%, 69/164) and 91 NTHi(56%, 91/164). In the control group, there were 14 strains of Hib and 49 strains of NTHi among 66 strains of Hi, which were isolated from 255 specimens(26%, 66/255). 24%(38/160) of Hi in the patient group produced beta-lactamase. In this group, the positive rate of beta-lactamase was 29%(20/69) for Hib strains and 20%(18/91) for NTHi strains. Sixteen strains resisting to ampicillin were beta-lactamase negative. CONCLUSIONS: These results indicate that Hib and NTHi are the major serotypes of Hi in both the patient and control group. The prevalence of Hib is higher in patients than in the control. Hib strains are more likely to produce beta-lactamase than NTHi.

Age Factors↗
PubMed1999

[Primary sarcoma of pulmonary artery: a case report].

OBJECTIVE: To call attention to the rare involvement of pulmonary artery by sarcoma. METHODS: To summarize the clinical, radiological and pathologic features of a case of pulmonary artery sarcoma. RESULTS: Pulmonary artery sarcoma has similar clinical manifestations as other pulmonary artery obstructive diseases (including pulmonary thromboembolism). The diagnosis should be considered in the patient with clinical presentations suggested pulmonary embolism. The radiological findings included unilateral hilar enlargement, contiguously soft tissue-filled pulmonary artery and pulmonary nodules and clinically deterioration was found after anticoagulant therapy. CONCLUSION: Pulmonary artery sarcoma is usually misdiagnosed as other pulmonary artery obstructive diseases. More attention should be paid to it.

Adult↗
PubMed1999

[Determination of enantiomeric purity for epinephrine by high performance liquid chromatography].

A procedure for the resolution of D,L-epinephrine and the determination of D-isomer ratio in a pharmaceutical formulation is described. The optical isomers of epinephrine were resolved by RP-HPLC with heptakis(2,6-di-O-methyl-beta-cyclodextrin) as a chiral mobile phase additives. The results showed that a correction factor must be introduced into the equation used for the calculation of the percentage of D-epinephrine, because the UV absorbance may not be the same when DM-beta-CD is present. Quantitation was achieved with external and internal standard method, HVA as an internal standard. This method can be used for the determination of the D-isomer in the L-epinephrine pharmaceutical formulation. The results showed that the mass fraction of D-isomer in the formulation increased during the period of storage.

Chromatography, High Pressure Liquid↗
PubMed1999

Clinical investigation of radiation retinopathy fundus and fluorescein angiographic features.

PURPOSE: To investigate the fundus and fluorescein angiographic features in the patients with radiation retinopathy. CLINICAL MATERIALS: Color fundus photography and/or fluorescein angiography from 13 patients with nasopharyngeal carcinomas received external beam radiation were retrospectively analyzed. RESULTS: In this study, 26 damaged eyes of 13 patients developed some degree of radiation retinopathy. The earliest and most common finding was macular microvascular changes (microaneurysms and/or telangiectasia), which was observed in 100% (26/26) of the eyes. Intraretinal hemorrhages, macular capillary nonperfusion, and mascular edema were noted in 84%, 50%, and 42% of the eyes, respectively. CONCLUSIONS: Radiation retinopathy is common after external beam radiation of nasopharyngeal carcinomas. The prominent changes include macular microvascular changes, intraretinal hemorrhages and macular capillary nonperfusion.

Adult↗
PubMed1998

Th1/Th2 cytokine expression in saliva of HIV-positive and HIV-negative individuals: a pilot study in HIV-positive individuals with oropharyngeal candidiasis.

Current data suggest that T-helper (Th)2-type cytokine responses are often associated with progression to AIDS in HIV-positive individuals. Similarly, Th2-type cytokines are associated with susceptibility to mucosal candidiasis, of which oropharyngeal candidiasis (OPC) is one of the most common opportunistic infections in HIV-positive individuals. Although little information is available on host defense mechanisms at the level of the oral mucosa, recent studies suggest that local cell-mediated immunity (CMI) is equally or more important than that in the periphery for host defense against mucosal Candida albicans infections. This study investigated the potential presence of oral-associated CMI through the expression of Th1/Th2-type cytokines in saliva of immunocompetent and immunocompromised individuals with and without OPC. Results showed a constitutive mixed Th1/Th2 cytokine expression (Th0) in whole saliva of healthy HIV-negative individuals. In contrast, HIV-positive individuals had a dominant Th2-type salivary cytokine profile (interleukin-4 [IL-4], IL-10) (IL-2, interferon-y [IFN-gamma], IL-12) that seemingly resulted from a lack of Th1-type cytokines rather than enhanced Th2-type cytokines. Moreover, pilot analyses of those with OPC showed evidence for a more profound salivary Th2-type profile. Both HIV-positive and HIV-negative patients, irrespective of CD4 counts, had some level of positive in vitro systemic lymphocyte proliferative responses to C albicans antigens. These results suggest that the Th1/Th2 cytokine dichotomy in HIV disease is detectable in situ in oral secretions and may be a useful indicator of oral-associated CMI to better understand resistance/susceptibility of HIV-positive individuals to oral opportunistic infections, including OPC.

AIDS-Related Opportunistic Infections↗
PubMed1998

Characterization of BRCA2: temperature sensitivity of detection and cell-cycle regulated expression.

People carrying a mutant BRCA2 gene are susceptible to breast, ovarian, pancreatic and other tumors. Many facets of BRCA2 have been studied, including its mutation in human cancers, its role in mouse embryogenesis and its RNA expression in different tissues and different mouse embryogenesis stages. However, there has been very little characterization of BRCA2 protein. We investigated the biochemical and biological properties of BRCA2 by using a monoclonal antibody we generated against the N-terminal portion of BRCA2. We discovered that the detection of BRCA2 by immunoblot analysis was sensitive to the temperature used to denature the samples before gel electrophoresis. BRCA2 was easily detectable when samples were denatured at low temperature instead of boiling. Although the precise mechanism underlying this observation is not clear yet, this finding will significantly improve our ability to study BRCA2. We examined the expression of BRCA2 using an immunoblot analysis protocol modified according to this observation. We showed that BRCA2 was presented in every human cell lines examined, including Capan-1, which expressed a truncated BRCA2 due to a BRCA2 frameshift mutation. We also showed that the expression of BRCA2 was cell-cycle regulated. Our results suggest that BRCA2 has an important role in cell growth regulation.

Antibodies, Monoclonal↗
PubMed1998

Aggrecan synthesis and secretion. A paradigm for molecular and cellular coordination of multiglobular protein folding and intracellular trafficking.

Each globular domain of exported multiglobular proteins putatively undergoes chaperone surveillance in the endoplasmic reticulum lumen. It is difficult to visualize how surveillance of multiple globular domains might be orchestrated and regulated. Aggrecan core protein has been used as a prototype for this problem by examining transfection of informative constructs into Chinese hamster ovary cells. The salient results are as follows: 1) aggrecan's N-terminal G1 domain is minimally secreted, and its flanking Golgi reporter sites are not decorated with glycsoaminoglycan chains; in contrast, its C-terminal G3 domain is readily secreted with flanking GAG chains, and G3 also facilitates G1 secretion; 2) G3 but not G1 can be intracellularly cross-linked to chaperone Hsp25; 3) G3 and Hsp25 remain noncovalently bound and are secreted together when G3 is situated N-terminal to its normal location; 4) exon 15, which encodes the center of G3's C-lectin subdomain, is necessary and sufficient for G3 secretion. A model is proposed in which Hsp25 piggybacks onto nascent G3 in the cytosol during a translocational pause and enters the ER lumen with G3, and once G3 properly folds, Hsp25 releases G3 and recycles to the nucleus while G3 continues to the Golgi stacks, providing passage for the entire core protein.

Aggrecans↗
PubMed1998

Demonstration of adhesion activity of the soluble Ig-domain protein C-CAM4 by attachment to the plasma membrane.

The carcinoembryonic antigen (CEA) family is a large group of proteins with immunoglobulin (Ig)-like structures. The membrane-associated CEA-family proteins have been shown to mediate intercellular adhesion. In addition to these membrane-associated proteins, several secreted CEA-like proteins, such as C-CAM4, PSG1b, and PSG11s, have also been identified. The functions of these soluble proteins are not clear because they cannot support intercellular adhesion like the membrane-associated proteins can. A fundamental question important for understanding the functions of these soluble proteins is whether they can interact in a homophilic fashion as do many of their membrane-associated homologues. We found that the homophilic interactions between these soluble proteins were too weak to be detected by solution binding assays. This is not unexpected because interactions between adhesion molecules are usually transient and weak to allow for control of association and dissociation. By expressing these soluble CEA-family proteins, C-CAM4, PSG1b, and PSG11s, as membrane-anchored forms, we showed that C-CAM4 could mediate intercellular adhesion, whereas PSG1b and PSG11s, despite their 52% identity to C-CAM4, could not. These results suggest that C-CAM4, but not PSG1b and PSG11s, can probably form homodimers. Thus, these secretory CEA-family members most likely have different interaction mechanisms, i.e., C-CAM4 might function as dimers, while PSGs might function as monomers.

Adenosine Triphosphatases↗
PubMed1998

Association of an 80 kDa protein with C-CAM1 cytoplasmic domain correlates with C-CAM1-mediated growth inhibition.

Decreased expression of C-CAM, a member of the CEA family of immunoglobulin like cell adhesion molecules, occurs in carcinomas of the colon, liver and prostate. Down regulation of C-CAM during the early stages of carcinogenesis in rat liver and human prostate has also been reported. We have recently shown that restoration of the expression of the isoform with long cytoplasmic domain, C-CAM1, leads to suppression of the tumorigenicity of prostatic carcinoma cells in vivo and growth suppression in vitro. These observations suggest that C-CAM1 may play an important role in regulating cell growth in normal tissues. Previous studies have demonstrated that the function of many members of the Ig-supergene family is dependent on interactions with cytoplasmic proteins. In the present study, we have used a bifunctional cross-linker to identify cellular proteins that interact directly with C-CAM1. Immunoblot analysis of WGA bound membrane proteins crosslinked with DSS identified a 180 kDa complex composed of C-CAM and an 80 kDa protein designated CAP-80 (C-CAM Associated Protein). Immunoprecipitation with anti-C-CAM antibodies showed that CAP-80 was co-precipitated with C-CAM from detergent solubilized, WGA-purified proteins. To assess the specificity of CAP-80 binding, the ability of CAP-80 to form stable complexes with C-CAM1 mutants expressed in insect cells was tested. Deletion of the cytoplasmic domain of C-CAM1 abolished complex formation whereas deletion of the extracellular Ig domains had no effect. These results suggest that a CAP-80 homologue (ICAP-80) is present in insect cells and ICAP-80 interacts with the cytoplasmic domain of C-CAM1. Replacement of Tyr488, a residue in the cytoplasmic domain known to be phosphorylated in vivo, with Phe did not diminish the association between C-CAM1 and ICAP-80, suggesting that Tyr488 phosphorylation is not required for association. The ability of various C-CAM1 mutants to associate with ICAP-80 correlated with their growth inhibitory activities, suggesting that ICAP-80/CAP-80 may play an important role in C-CAM1-mediated growth inhibition.

Adenosine Triphosphatases↗
PubMed1998

Transgenic approaches to define the functional role of dual site phospholamban phosphorylation.

Phospholamban is a critical regulator of the sarcoplasmic reticulum Ca2+-ATPase activity and myocardial contractility. Phosphorylation of phospholamban occurs on both Ser16 and Thr17 during isoproterenol stimulation. To determine the physiological significance of dual site phospholamban phosphorylation, we generated transgenic models expressing either wild-type or the Ser16 --> Ala mutant phospholamban in the cardiac compartment of the phospholamban knockout mice. Transgenic lines with similar levels of mutant or wild-type phospholamban were studied in parallel. Langendorff perfusion indicated that the basal hyperdynamic cardiac function of the knockout mouse was reversed to the same extent by reinsertion of either wild-type or mutant phospholamban. However, isoproterenol stimulation was associated with much lower responses in the contractile parameters of mutant phospholamban compared with wild-type hearts. These attenuated responses were due to lack of phosphorylation of mutant phospholamban, assessed in 32P labeling perfusion experiments. The lack of phospholamban phosphorylation in vivo was not due to conversion of Ser16 to Ala, since the mutated phospholamban form could serve as substrate for the calcium-calmodulin-dependent protein kinase in vitro. These findings indicate that phosphorylation of Ser16 is a prerequisite for Thr17 phosphorylation in phospholamban, and prevention of phosphoserine formation results in attenuation of the beta-agonist stimulatory responses in the mammalian heart.

Animals↗
PubMed1998

Inactivation and conformational changes of fatty acid synthase from chicken liver during unfolding by sodium dodecyl sulfate.

Fatty acid synthase is an important enzyme participating in energy metabolism in vivo. The inactivation and conformational changes of the multifunctional fatty acid synthase from chicken liver in SDS solutions have been studied. The results show that the denaturation of this multifunctional enzyme by SDS occurred in three stages. At low concentrations of SDS (less than 0.15 mM) the enzyme was completely inactivated with regard to the overall reaction. For each component of the enzyme, the loss of activity occurred at higher concentrations of SDS. Significant conformational changes (as indicated by the changes of the intrinsic fluorescence emission and the ultraviolet difference spectra) occurred at higher concentrations of SDS. Increasing the SDS concentration caused only slight changes of the CD spectra, indicating that SDS had no significant effect on the secondary structure of the enzyme. The results suggest that the active sites of the multifunctional fatty acid synthase display more conformational flexibility than the enzyme molecule as a whole.

Animals↗