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Biomedical subjects

M Liang

Publications and source records attributed to M Liang.

At least 73 records · Page 4Linked to original sources
PubMed1998

Phosphorylation and functional desensitization of the alpha2A-adrenergic receptor by protein kinase C.

We have investigated the potential for protein kinase C (PKC) to phosphorylate and desensitize the alpha2A-adrenergic receptor (alpha2AAR). In whole-cell phosphorylation studies, recombinantly expressed human alpha2AAR displayed an increase in phosphorylation after short-term exposure to 100 nM phorbol 12-myristate-13-acetate (PMA) that was blocked by preincubation with a PKC inhibitor. This increase in receptor phosphorylation over basal amounted to 172 +/- 40% in COS-7 cells and 201 +/- 40% in Chinese hamster ovary cells. In permanently transfected Chinese hamster fibroblast cells, PKC activation by brief exposure of the cells to PMA resulted in a marked desensitization of alpha2AAR function, amounting to a 68 +/- 4% decrease in the maximal agonist (UK14304)-stimulated intracellular calcium release. Such desensitization was blocked by the PKC inhibitor bisindolylmaleimide I and was not evoked by an inactive phorbol ester. The desensitization of this agonist response was not caused by PKC-mediated augmentation of G protein-coupled receptor kinase activity, because PMA-promoted desensitization of a mutated alpha2AAR that lacked G protein-coupled receptor kinase phosphorylation sites was identical to that of wild-type alpha2AAR. To test whether PKC phosphorylation is a mechanism by which alpha2AAR can be regulated by other receptors, the alpha1bAR was co-expressed with the alpha2AAR in Chinese hamster ovary cells. Upon selective activation of alpha1bAR, the function of alpha2AAR underwent a 53 +/- 5% desensitization. Thus, cellular events that result in PKC activation promote phosphorylation of the alpha2AAR and lead to substantial desensitization of receptor function. This heterologous regulation also represents a mechanism by which rapid crosstalk between the alpha2AAR and other receptors can occur.

Animals↗
PubMed1998

[Effect of ischemia/reperfusion in cardiac surgery with cardiopulmonary bypass on nitric oxide levels of peripheral blood in patients].

To examine the effect of ischemia/reperfusion in cardiac surgery with cardiopulmonary bypass (CPB) on nitric oxide (NO) levels of peripheral blood, venous levels of NO2- and NO3- were measured at multiple time-points before, during, and after CPB by means of high-pressure liquid chromatograph to reflect NO concentration indirectly in 20 patients. The results showed there was a linear regression between the decreased trend of NO release at the period of peri-CPB is related to the endothelial cell activation caused by ischemia/reperfusion at the same time. Therefore it is necessary to explore the regulation and action of NO release during systemic inflammatory response procedure in CPB.

Adult↗
PubMed1997

Baculovirus expression of a human G2-specific, neutralizing IgG monoclonal antibody to Puumala virus.

We amplified by polymerase chain reaction the heavy- and light-chain antibody genes of a human hybridoma secreting a neutralizing, IgG monoclonal antibody to the G2 protein of Puumala virus. The heavy- and light-chain genes were cloned and sequenced and the deduced amino acids were aligned with those of other human antibodies to identify the constant and variable regions. The genes were cloned into the baculovirus plasmid transfer vector pACUW51 such that the heavy-chain and light-chain genes were under control of the baculovirus polyhedrin or p10 promoters, respectively. The transfer vector plasmid was cotransfected into cultured Spodoptera frugiperda (Sf9) cells with linearized DNA of the baculovirus Autographa californica nuclear polyhedrosis virus, and recombinant baculoviruses were selected by plaque formation on monolayers of Sf9 cells. Expression and secretion of an IgG monoclonal antibody was confirmed by assay of recombinant-infected Sf9 cell supernatants for the presence of the heavy and light chains. Specificity of the expressed human antibody was determined by immune-precipitation of radiolabeled Puumala virus proteins and by ELISA with Puumala virus-infected cell lysates. Similar quantities of the expressed IgG and the authentic monoclonal antibody neutralized Puumala virus in plaque-reduction neutralization assays. Neither the authentic nor the recombinant antibody could passively protect hamsters from challenge with Puumala virus; however, our results demonstrate the potential of this methodology for production of biologically active neutralizing antibodies.

Amino Acid Sequence↗
PubMed1997

Simultaneous rapid high-performance liquid chromatographic determination of phenytoin and its prodrug, fosphenytoin in human plasma and ultrafiltrate.

A reversed-phase high-performance liquid chromatographic assay for the simultaneous determination of phenytoin and fosphenytoin, a prodrug for phenytoin, in human plasma and plasma ultrafiltrate is described. For plasma, the method involves simple extraction of drugs with diethyl ether and evaporation of solvent, followed by injection of the reconstituted sample onto a reversed-phase C18 column. Plasma ultrafiltrate is injected directly into the HPLC column. Compounds are eluted using an ion-pair mobile phase containing 20% acetonitrile. The eluent is monitored by UV absorbance at 210 nm. The fosphenytoin standard curves are linear in the concentration range 0.4 to 400 microg/ml for plasma and 0.03 to 80 microg/ml for ultrafiltrate. Phenytoin standard curves are linear from 0.08 to 40 microg/ml for plasma and from 0.02 to 5.0 microg/ml for ultrafiltrate. No interferences with the assay procedure were found in drug-free blank plasma or plasma ultrafiltrate. Relative standard deviation for replicate plasma or ultrafiltrate samples was less than 5% at concentrations above the limit of quantitation for both within- and between-run calculations.

Anticonvulsants↗
PubMed1997

Lack of corneal toxicity of interferon Alpha-2b administered subconjunctivally after sclerectomy.

PURPOSE: To evaluate the corneal toxicity of subconjunctival injection interferon alpha-2b at filtering bleb after sclerectomy in white rabbits. METHODS: Eight rabbits which had been performed sclerectomy were randomly divided into two groups. Each group consisted of four rabbits. Eight eyes in group 1 were subconjunctivally received interferon alpha-2b 5 x 10(5) IU/0.2 ml into filtering bleb from the edge of the filtering site immediately after operation and every postoperative day. The other eight eyes in group 2 were injected with 0.2 ml normal saline. All of the eyes underwent daily examination by slip-lamp microscopy and direct ophthalmoloscopy. Sodium fluorescein was used to assess corneal epithelial integrity. On day 3, 4, 7 and 14, every two rabbits (group 1 and 2 each, respectively) were killed and removed cornea immediately to take examination of the viability of corneal endothelium by dual staining with typan blue and alizanin red S. RESULTS: No sign of toxicity in corneal epithelium and endothelium were found following continuously injection interferon alpha-2b at filtering bleb 3-14 days totally for selected doses. CONCLUSION: Subconjunctivally administered interferon alpha-2b at filtering bleb after glaucoma filtering surgery may be a safe drug-applied method.

Animals↗
PubMed1997

[Study on the immune state of patients with laryngeal carcinoma].

The authors have carried out the immunoassay on 68 patients with laryngeal carcinoma in order to investigate the relationship between the occurrence and development of the tumour and the body immune state by using the methods of R1D, APAAP and LDH. The results showed that, in comparison with the normal group, CD3+, CD4+ cell and NK cell activity were much lower (P < 0.01), CD8+ cell slightly increased (P > 0.05). IgG, IgA and IgM were also lower (P < 0.05). It indicates that the lower level of cellular immunity, the descent of the ratio of CD4+/CD8+ and the condition which suppresses the body immune system are the interior factors which make the laryngeal carcinoma happening and developing easily. With the development of tumor, the increase of various suppressor factors and the immune system suppressed further the tumor can spread and shift much more easily.

Adult↗
PubMed1997

Effects of removing circulatory tumor necrosis factor by immunoadsorption on experimental endotoxin shock animals.

OBJECTIVE: To evaluate the effects of removing circulatory tumor necrosis factor (TNF) by immunoadsorption on endotoxin shock animals. METHODS: Sixty New Zealand white rabbits were injected intravenously with lethal dose of endotoxin (10 Billion cfu/kg E. Coli endotoxin) and randomly divided into 3 groups: perfusion group, hemoperfusion started at 1 hour after injecting endotoxin through immunoadsorbent columns against TNF; pseudoperfusion group, hemoperfusion through blank columns; and control group, injected with endotoxin only. The arterial pressure, microcirculation of the mesentery, plasma levels of TNF, IL-1, IL-6, IL-8, nitrite, endothelin-1 (ET-1), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine were measured and analyzed and finally the survival rate was observed. RESULTS: Plasma levels of TNF were sharply reduced after immunoadsorption. Moreover, release of IL-1, IL-6, IL-8, NO and ET-1 were also attenuated. Hemodynamic abnormalities could be improved and survival rate ameliorated significantly. CONCLUSION: Specific immunoadsorption of circulating TNF might be a new and effective therapy for endotoxin shock.

Animals↗
PubMed1996

Bacterial expression of neutralizing mouse monoclonal antibody Fab fragments to Hantaan virus.

We amplified by polymerase chain reaction the heavy and light chain antibody genes of two mouse hybridomas secreting neutralizing monoclonal antibodies (MAbs) to the G1 or G2 envelope proteins of Hantaan virus, cloned them into the phagemid vector pComb3, and expressed them in bacteria to yield Fab fragments. Expressed Fab fragments had the same antigenic specificities for Hantaan and Seoul viruses as the complete parent MAbs and were able to neutralize Hantaan virus in plaque-reduction neutralization assays. The authentic MAb to G2 (HCO2) could passively protect hamsters from challenge with Hantaan virus when neutralizing antibody titers of at least 1:10 were detected in the animals' sera just prior to challenge. In contrast, although 1:10 neutralization titers were also detected in hamsters receiving passively transferred, Escherichia coli-expressed HCO2 Fab, these animals were not protected from infection with Hantaan virus. Similarly, passive transfer of the HCO2 Mab on Days 1 through 4 after infection prevented antigen deposition in hamster lungs and kidneys but passive transfer of the recombinant HCO2 Fab did not. The results suggest that although neutralization by IgG antibodies correlates with protection in hamsters, the same may not be true for neutralizing Fab fragments.

Amino Acid Sequence↗
PubMed1996

The development and initial validation of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index for systemic lupus erythematosus.

OBJECTIVE: To develop and perform an initial validation of a damage index for systemic lupus erythematosus (SLE). METHODS: A list of items considered to reflect damage in SLE was generated through a nominal group process. A consensus as to which items to be included in an index was reached, together with rules for ascertainment. Each center submitted 2 assessments, 5 years apart, on 2 patients with active and 2 with inactive disease, of whom 1 had increased damage and the other had stable disease. Analysis of variance was used to test the factors physician, time, amount of damage, and activity status. RESULTS: Nineteen physicians completed the damage index on 42 case scenarios. The analysis revealed that the damage index could identify changes in damage seen in patients with both active and inactive disease. Patients who had active disease at both time points had a higher increase in damage. There was good agreement among the physicians on the assessment of damage in these patients. CONCLUSION: This damage index for SLE records damage occurring in patients with SLE regardless of its cause. The index was demonstrated to have content, face, criterion, and discriminant validity.

Health Status Indicators↗
PubMed1996

Phase I and pharmacologic study of 9-aminocamptothecin given by 72-hour infusion in adult cancer patients.

PURPOSE: To conduct a phase I and pharmacologic study of the new topoisomerase I inhibitor, 9-aminocamptothecin (9-AC). PATIENTS AND MATERIALS: A 72-hour infusion of 9-AC was administered every 14 days to 48 solid-tumor patients at doses of 5 to 59 microg/m2/h without granulocyte colony-stimulating factor (G-CSF) and 47 to 74 microg/m2/h with G-CSF. RESULTS: Without G-CSF, two of eight patients who received 47 microg/m2/h had dose-limiting neutropenia in their initial cycle, as did both patients who received 59 microg/m2/h (with a platelet count < 25,000/microL in one). With G-CSF, zero of seven patients treated with 47 microg/m2/h had dose-limiting neutropenia in their first cycle, while dose-limiting neutropenia occurred in six of 14 patients (with platelet count < 25,000/microL in five) entered at 59 microg/m2/h. Among 39 patients entered at > or = 25 microg/m2/h 9-AC with or without G-CSF, fatigue, diarrhea, and nausea/vomiting of grade 2 severity ultimately occurred in 54%, 30%, and 38%, respectively, while grade 3 toxicities of each type occurred in 8% of patients. Steady-state 9-AC lactone concentration (Css) increased linearly from 0.89 to 10.6 nmol/L, and correlated strongly with leukopenia ( r = .85). CONCLUSION: The recommended phase II dose of 9-AC given by 72-hour infusion every 2 weeks is 35 microg/m2/h without G-CSF or 47 microg/m2/h with G-CSF support. Dose escalation in individual patients may be possible according to their tolerance.

Adult↗
PubMed1996

Gastrin-releasing peptide receptor signaling resulting in growth inhibition.

We demonstrate that gastrin-releasing peptide (GRP) can inhibit the proliferation of human immortal nontumorigenic (184-B5) mammary epithelial cells ectopically expressing the human GRP receptor. Growth of Balb 3T3 cells ectopically expressing relatively high levels of the GRP receptor was also inhibited by GRP; however, growth of transfectants expressing lower levels of the receptor was not inhibited. Compared with Balb 3T3 cells, mammary epithelial cells could be rendered sensitive to growth inhibition by GRP by the expression of fewer GRP receptors. GRP also stimulated DNA synthesis in quiescent, serum-starved Balb 3T3 transfectants. In clones that were sensitive to growth inhibition by GRP by virtue of their expression of relatively high levels of the GRP receptor, the dose-response curve of GRP-stimulated DNA synthesis was bell shaped. This is consistent with our conclusion that the growth-inhibiting activity of GRP required the activation of a relatively large pool of receptors in Balb 3T3 cells. Significantly, prostaglandin H synthase inhibitors, which block the production of prostaglandins from arachidonic acid, reduced GRP-inhibitory effects on DNA synthesis. We also compared a number of GRP-stimulated signaling pathways in Balb 3T3 clones that were sensitive or insensitive to growth inhibition by GRP, including cAMP formation, phospholipase C activation, calcium mobilization, and arachidonic acid formation. Taken together, these results demonstrate a novel GRP receptor-coupled signal pathway promoting growth inhibition in which prostaglandin H synthase plays a significant role.

3T3 Cells↗
PubMed1996

[Determination of metronidazole in serum by HPLC].

This paper report a sensitive and rapid method for the determination of metronidazole (MTZ) using theophylline as the internal standard. High performance liquid chromatograph model 344 (Beckman) with a 254 nm wavelength UV detector and YWG-C18H37 column (10 microns, 250 x 4.6 mm) was used. To the serum sample 200 microliters, 100 microliters phosphate buffer (0.8 mol/L, pH 7.5) was added, then extracted with 3 ml chloroform containing 5% isopropyl alcohol. The organic layer was removed and evaporated to dryness under an air stream in a 40 degrees C water bath. The residue was dissolved in 30 microliters mobile phase and 20 microliters injected. The mobile phase of water-methanol (73:27) was pumped at 1.0 ml/min through the column. The detector operated at 0.005 aufs. The retention times for MTZ and theophylline were 5.78 and 6.81 min respectively. Standard curve was linear in the concentration range of 0.3125 to 20 mg/L. The detection limit in serum was 0.02 mg/L. Extraction recovery was 77%-82%; method recovery 99%-102%; withinday RSD less than 3.0%; inter-day RSD less than 3.5%.

Chromatography, High Pressure Liquid↗
PubMed1996

[Chemosensitivity test for head and neck cancers].

The chemosensitivities of 27 fresh specimens of head and neck cancers were tested with MTT assay to study the practicability and accuracy of the assay for the examination of chemosensitivity in head and neck cancer patients. The chemosensitivities among cancers of different primary sites, pathologic types, histological differentiations, DNA ploidies and estrogen receptors were compared in an attempt to evaluate the choice of anticancer drugs for individual chemotherapy. Eight anticancer drugs: Methotroxate (MTX), Mitomycin C (MMC), fluorouracil (5-Fu), Carboplatin (CBDCA), Pingyangmycin (PYM), Homoharringtonine (HHA), Etoposid (VP16) and Vincristine (VCR) were included. The success rate of MTT assay in the present study was 92.6% and the accuracy was relatively high. The sensitivity sequence was PYM > HHA > MTX > CBDCA > MMC > 5-Fu > VCR > VP16, which suggested HHA should be recommended first to the chemotherapy of head and neck cancer. No chemosensitivity differences were found among different primary sites histological differentiations and estrogen receptors. The chemosensitivity of squamous cell carcinoma was significantly higher than that of adenoid cystic carcinoma. The chemosensitivity of aneuploid tumor was significantly higher than that of diploid.

Adult↗
PubMed1995

Primary structure of hepatocyte nuclear factor/forkhead homologue 4 and characterization of gene expression in the developing respiratory and reproductive epithelium.

Members of the winged helix/forkhead family of transcription factors are believed to play a role in cell-specific gene expression. A cDNA encoding a member of this family of proteins, termed hepatocyte nuclear factor/forkhead homologue 4 (HFH-4), has been isolated from rat lung and rat testis cDNA libraries. This cDNA contains an open reading frame of 421 amino acids with a conserved DNA binding domain and several potential transactivating regions. During murine lung development, a single species of HFH-4-specific transcript (2.4 kb long) is first detected precisely at the start of the late pseudoglandular stage (embryonic day 14.5) and, by in situ hybridization, is specifically localized to the proximal pulmonary epithelium. The unique temporal and spatial pattern of HFH-4 gene expression in the developing lung defines this protein as a marker for the initiation of bronchial epithelial cell differentiation and suggests that it may play an important role in cell fate determination during lung development. In addition to expression in the pulmonary epithelium, RNA blot analysis reveals 2.4-kb HFH-4 transcripts in the testis and oviduct. By using mice with genetic defects in spermatogenesis, HFH-4 expression in the testis is found to be associated with the appearance of haploid germ cells and in situ hybridization studies indicate that HFH-4 expression is confined to stages I-VII of spermatogenesis. This pattern of HFH-4 gene expression during the early stages of differentiation of haploid germ cells suggests that HFH-4 may play a role in regulating stage-specific gene expression and cell-fate determination during lung development and in spermatogenesis.

Aging↗
PubMed1995

Health status instruments / utilities.

Rheumatologists and other interested professionals at the OMERACT II conference formed small groups to discuss whether it was sensible to use a generic health status instrument in musculoskeletal disease trials. These instruments promise the possibility of comparison of health status between disease states. However, data is lacking on validity of the current generation of instruments to support their use. Participants had little personal experience with these instruments. After inspection, many voiced strong concerns over comprehensiveness and responsiveness. Many dimensions of health relevant for patients with this group of diseases were felt to be underrepresented. The dimension of adverse effects was universally absent, although this is more a problem of state of the art in trial methodology than a problem of these measures. Although there is little data, the small number of response categories in the dimensions covered, plus the lack of comprehensiveness, make it likely that responsiveness will be low. Further research, especially the adoption of one or more generic measures alongside specific measures, both in trials and in observational studies, is necessary to validate and improve the current generic measures. Until that time, valid conclusions and health policy regarding musculoskeletal diseases cannot be based on generic measures of health status.

Health Status↗