Biomedical subjects

B Liu

Publications and source records attributed to B Liu.

At least 343 records · Page 19Linked to original sources

PubMed1999

[Sub-cloning and preliminary sequence analysis of the gene encoding of a cefoperazone hydrolyzing beta-lactamase isolated from Escherichia coli].

Escherichia coli HX88108, which is resistant to cefoperazone(CPZ), was isolated from a severely infected patient. We studied genetical basis of beta-lactamase produced in E. coli HX88108 by pFL25, one of the recombinant plasmid of pFC. Largescale pFL25 plasmid was extracted, purified, and cleaved with restriction endonuclease EcoR I, Sal I, Pvu I, then subcloned into vector pUC19 as 1.9 kb, 0.9 kb, 0.65 kb fragments respectively. Recomminant plasmids were selected by alpha-complementation and determined by restriction endonuclease analysis. DNA sequencing was performed by the dideoxy polymerase chain termination method. Partial nucleotide sequence(1-78 nucleotide position) of the gene was found to be highly homologous (97%) with the gene coding for TEM-52 extended spectrum beta-lactamase of K. pneumonise, suggesting that the beta-lactamase coded by the cefoperazone resistant gene might be derived from TEM-type beta-lactamase.

Anti-Bacterial Agents↗

PubMed1999

[Study on the contents of serum HDL subclasses in type N hyperlipidemics].

Contents of serum HDL subclasses in normolipidemics (n = 24) and type IV hyperlipidemics (n = 24) were determined using two-dimensional gel electrophoresis associated with immunodetection method. The results showed that the contents of pre-beta 1 HDL (P < 0.001) and HDL3a (P < 0.05) increased significantly and that of HDL2b (P < 0.001) decreased significantly in hyperlipidemics, compared with normolipidemics. Serum TG concentrations of hyperlipidemics showed positive correlation with pre-beta 1 HDL (r = 0.582) and HDL3a (r = 0.692) and negative correlation with HDL2b (r = -0.506) and HDL2a (r = -0.552). These results indicated that the maturation of HDL could be abnormal in type IV hyperlipidemics.

Adult↗

PubMed1999

[Effects of hexamethylene bisacetamide on P53 protein expression of MEC-1 cell line and cell differentiation].

OBJECTIVE: To investigate the relationship between the differentiation of the mucoepidermoid carcinoma cell line MEC-1 induced by HMBA and the expression of P53 protein. METHODS: Effects of HMBA on the growth of MEC-1 cells in vitro were measured with MTT colorimetric assay, and the content of DNA in cells was assayed by using Feulgen's staining. The P53 protein expression of MEC-1 cells was detected with ABC immunohistochemistry with anti-mutant P53 protein antibody, and the distribution of cells in different differentiation phase was determined by flow cytometry. RESULTS: HMBA inhibited the growth of MEC-1 cells in a dose-dependent and time-dependent manner, and HMBA-treated MEC-1 cells were arrested in the G1 phase and had a lower content of DNA and a lower level of P53 protein compared with the control group. CONCLUSION: The differentiation of MEC-1 cells induced by HMBA may be associated with the regulation of HMBA on the P53 protein expression and the cell differentiation cycle.

Acetamides↗

PubMed1999

[Complete overdenture retained with implants and bar-clip attachments].

OBJECTIVE: To sum up and evaluate the applied experience and applied effects of implants and bar-clip attachments in complete overdenture. METHODS: Bar-clip attachments were used as a super structure of implant to manufacture complete overdenture in three designs: mucosa, implant-mucosa, and implant supporting way. The retentive force of the overdenture was measured with measuring instrument of retentive force of prosthesis. RESULTS: All three designs could obtain good retentive effect, specially implant-mucosa supporting and implant supporting designs, which were of more better stability and supporting effect; 2-3 nelon clips could supply 10-15 N retentive force to the overdenture. CONCLUSION: The complete overdenture retained with implant and bar-clips attachments is a very effective way for restoration of endtulous patients, which should be applied more popularly.

Dental Implants↗

PubMed1999

[Evaluation of N staging of cervical lymph nodes with positive palpation in laryngeal carcinoma].

OBJECTIVE: To evaluate N staging of cervical lymph nodes with positive palpation objectively. METHOD: Serial sections of lymph nodes of neck dissections with transparent methods were observed under light microscope. RESULT: 81 lymph nodes with pathological metastases were verified in 100 patients with 114 palpation positive lymph nodes. The correspondent rate was 71.1%. The correspondent rate of clinical N via pathological N staging was N1 35.6%, N2a 25.0%, N2b 58.3%, N2c 75.0%, N3 100.0% respectively. CONCLUSION: N staging judged only by palpation is not sufficient in clinic. It should be combined with other examinations.

Carcinoma, Squamous Cell↗

PubMed1999

[Inhibitory Effects of Etoposide Combined with 8-methoxypsoral en on Highly Metastatic Human Mucoepidermoid Carcinoma Cells].

OBJECTIVE: To study the inhibitory effects of Etoposide (VP16) combined with 8-methoxypsoralen (8-MOP) on human highly metastatic mucoepidermoid carcinoma cells (Mc3). METHODS: Mc3 cells were exposed to the drugs and their combinations at various concentrations. The inhibitory effects were tested with microculture tetrazolium colorimetric assay (MTT assay) and cologenic assay. RESULTS: The IC50 values of VP16 and 8-MOP were 1625. 25 ng/ml and 750000 ng/ml respectively, the CI50 of the combination at 100320 and 1000 ng/ml of VP16 with 8-MOP were 0.350, 0.599 and 0.880 respectively. CONCLUSION: The data indicate that combination of VP16 and 8-MOP is synergic in the inhibition of Mc3 cell growth.

Carcinoma, Mucoepidermoid↗

PubMed1999

[Comparison of protocatechuic aldehyde in different processed products of Salvia miltiorrhiza].

The contents of Protocatechuic aldehyde in crude and four different processed products of Salvia miltiorrhiza were determined by HPLC. The results showed that, after processing, the contents of Protocatechuic aldehyde decreased in varying degrees. Among them, the processed products fried with wine, vinegar and no materials decreased 17.14%, 20.00% and 42.86% respectively. The carbonized product decreased 60.86%.

Acetic Acid↗

PubMed1999

Immunocytochemical study of cells in the vitreous of proliferative vitreoretretinopathy.

PURPOSE: To identify the cellular components of vitreous samples obtained during vitrectomy for proliferative vitreoretinopathy (PVR). METHODS: With the use of three intermediate filament (IF) proteins, vimentin, glial fibrillary acidic protein (GFAP), and cytokeratin (CK), cytocentrifuge slides of 14 fresh vitreous aspirates were detected with immunohistochemical technique. RESULTS: All the specimens contained epithelial-like proliferative cells with or without pigment and some membrane-like pieces. Immunocytochemical staining showed that 76.0-90.0% cells stained for CK, 17.4-29.6% cells expressed GFAP, and 80.1-91.0% cells were positive for vimentin. CONCLUSIONS: Majority of cells in the vitreous samples originated from retinal pigment epithelial cells (RPE) and glial cells in PVR. Expression of IF proteins may be determined by tissue of origin and local microenvironment.

Adolescent↗

PubMed1999

[The design of a multi-parameter patient monitor].

This paper describes the software and hardware design of a multi-parameter patient monitor which is able to measure ECG, heart rate, blood pressure, breath rate, body temperature and oxygen saturation non-invasively. The instrument uses embedded industry control module as its main controller and 9" CRT as its display. Several OEM modules are utilized in the design, such as ECG module, blood pressure module and oximeter module. This design strategy has the features of reliable performance, easy maintenance, and short developing period.

Diagnostic Equipment↗

PubMed1999

[Auditory neuropathy].

OBJECTIVE: To study the clinical feature and audiological and electrophysiological characteristics of auditory neuropathy. METHODS: The history, audiometry, stapedial reflex, electrocochleogram, auditory brainstem response, promontory stimulation tests, otoacoustic emissions (OAE) and its contralateral supression tests were studied in 17 cases of auditory neuropathy. RESULTS: The patients were predominently female teenagers with a history of gradual onset of bilateral hearing loss, pure tone auditometry revealed symmetric ascending audiograms with moderate hearing loss at frequencies below 1 kHz, but relatively normal hearing at 2 kHz and above. Speech reception thresholds were between 40 to 85 dB HL, discrimination score was from 29% to 68%. Stapedial reflex, auditory brainstem response and compound action potentials were absent or threshold elevated disproportionately to the pure tone threshold. All of the patients had normal cochlear microphonics and robust spontaneously and transiently evoked otoacoustic emissions (SOAE and TEOAE), the TEOAE showed no contralateral suppression effects as seen in normal subjects. CONCLUSION: The diagnosis of the disease depends on the discrepancies between subjective and objective hearing and pre-neural and neural responses. The crossed olivocochlear bundle function testing in terms of contralateral acoustic stimulation induced otoacoustic emission reduction is specific for differential diagnosis. There is a need for more awareness of the disease among otolaryngologists and neurologists.

Acoustic Impedance Tests↗

PubMed1999

[Cervical lymph node metastasis and recurrence in supraglottic carcinoma after operation].

OBJECTIVE: To evaluate the regional control efficacy of elective neck dissection (END) in patients with supraglottic carcinoma. METHODS: The incidence of cervical recurrences of 582 patients with supraglottic carcinoma treated in this hospital from 1981 to 1993 were retrospectively reviewed. RESULTS: Three hundred and ninety-two cases (67.35%) of this group had T3 and T4 primary lesions. Among them, 147 cases (37.50%) had positive nodes(N+) and this accounted for 86.47% (147/170) of all N+ patients. Ipsilateral or bilateral cervical recurrence occurred in 33 of 126 (26.19%) node negative (N0) cases who had not had neck dissection and 30 of them (90.90%) were among T3 and T4 groups. However, Contralateral lymph node recurrence occurred only in 40 of 286(13.99%) N0 cases who had had END and 30 of them (75%) were among T3 and T4 groups. There were 163 cases who were readmitted and received surgery again for different purposes. The three and five year survival rates in the second stage END group were 86.67% and 77.78%, in metastasis group 64.81% and 32.50%, in recurrent group 33.33% and 30.77% respectively. There were significant differences in survival rates among these groups. CONCLUSION: Patients underwent elective neck dissection achieved better survival than those on "wait and watch" policy and salvage surgery. Elective neck dissection is recommended for the treatment of supraglottic carcinoma, especially for the T3 and T4 diseases.

Adult↗

PubMed1999

[Flotation spectrophotometric determination of copper on isochromatic dye ion pair with crystal violet and bromopnenol blue].

Bromophenol blue (BPB) was produced and entered into the aqueous phase when NaOH solution of pH = 10 was added to Cu(biq)2BPB by trichloromethane and isoamyl alcohol (20:1) extractive. And then CV x BPB was floated by crystal violet (CV) with benzene solution. The flotation was dissolved in ethanol and the absorbance of the solution measured at 590 nm. The sensitivity was raised because of the two dyes assistant effect. The molar absorptivity was 1.45 x 10(5) L x mol(-1) x cm(-1). Copper in the sample was separated first by extracting the Cu(biq)2BPB complex with trichloromethane and isoamyl alcohol, thus achieving a high selectivity. Beer's law was obeyd in the range of 0-0. 4 mg/L with a relative standard deviation of 3.6%. For 4.8 x 10(-8) g/mL copper solution, the recoveries were 97.8%-101.7%.

Bromphenol Blue↗

PubMed1999

[Determination of trace selenium in spirulina by continuous-flow hydride generation atomic absorption spectrometry].

The mixed solutions of the hydrogenized element-NaOH-NaBH4 and HCI solution were fed into hydride vapor generator at the same rate by multi-flow peristaltic pump. Selenium element in the aqueous solution reacted on the nascent hydrogen to generate gaseous hydride. No separation was needed and the method was highly sensitive with little interference. The selenium content in spirulina was determined and a reliable analytical method was established. The determination limit of the method was 0.017 microg x g(-1), and the recovery of the samples was 98.89%-101.20%.

Selenium↗

PubMed1999

[Absorption characteristics of the isochromatic dye ion-pair formed by tetrabromofluorescein and buthylrhodamine B].

Absorption properties of tetrabromofluorescein (TBF) and buthylrhodamine B (BRB) and the isochromatic dye ion-pair formed by TBF and BRB were studied. The experiment showed that the proportion of TBF: BRB was 1:2 at pH=7 with Ksp = 2.16 x 10(-18), and the extraction rate was 84.2%. This provides a basis for the application of TBF and BRB to extraction spectrophotometry.

English Abstract↗

PubMed1999

[Floatation spectrophotometric determination of metals with isochromatic dye ion-pairs tetrabromofluorescein-rhodamine 6G system].

The floatation spectrophotometric determination of germanium, platinum and ferrum with isochromatic dye ion-pairs formed by tetrabromofluorescein (TBF) and rhodamine 6G (R6G) is described. The association complexes of these metallic ions with rhodamine 6G floated with organic solvent were first allowed to react on basicity, and then on tetrabromofluorescein which is of the same color as rhodamine 6G. The isochromatic dye ion-pairs of R6G x TBF were floated with toluene. The floatation R6G x TBF in acetone was dissolved and the absorbance of the solution at 530 nm was measured. The sensitivity is raised because of the 2 m dyes. The molar absorptivities for Ge, Pt and Fe are greater than 10(5) L mol(-1) cm(-1).

English Abstract↗

PubMed1999

[Study on the double fluorescers fluorometry and its application].

Butylrhodamine B (BRB) was produced and entered into aqueous phase when pH=8.7 buffer solution was added to toluene extractive solution of GaCl4BRB+. And then BRB2 x TBF was extractred by tetrabromofluorescein (TBF). N-butanol (toluene:n-butanol 1:1) was added to toluene extractive solution of BRB2 x TBF. The sensitivity was raised because of the assistant effect of BRB2 x TBF. The detection limit was 0.1 microg/L. Beer's law was obeyed in the range of 0-0.15 mg/L with a relative standard deviation of 3.9% for 0.0027% gallium in metal and the recoveries were 94.7%-105.2%.

English Abstract↗

PubMed1998

Purification and characterization of a membrane bound neutral pH optimum magnesium-dependent and phosphatidylserine-stimulated sphingomyelinase from rat brain.

Sphingomyelin hydrolysis and ceramide generation catalyzed by sphingomyelinases (SMase) are key components of the signaling pathways in cytokine- and stress-induced cellular responses. In this study, we report the partial purification and characterization of the membrane bound, neutral pH optimal, and magnesium-dependent SMase (N-SMase) from rat brain. Proteins from Triton X-100 extract of brain membrane were purified sequentially with DEAE-Sephacel, heparin-Sepharose, ceramic hydroxyapatite, Mono Q, phenyl-Superose, and Superose 12 column chromatography. After eight purification steps, the specific activity of the enzyme increased by 3030-fold over the brain homogenate. The enzyme hydrolyzed sphingomyelin but not phosphatidylcholine and its activity was dependent upon magnesium with an optimal pH of 7.5 and a native pI of 5.2. Delipidation of the enzyme through chromatographic purification or by extraction with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid followed by gel filtration revealed that the enzyme became increasingly dependent on phosphatidylserine (PS). Up to 20-fold stimulation was observed with PS whereas other lipids examined were either ineffective or only mildly stimulatory. The Km of the enzyme for substrate sphingomyelin (3.4 mol %) was not affected by PS. The highly purified enzyme was inhibited by glutathione with a >95% inhibition observed with 3 mM glutathione and with a Hill number calculated at approximately 8. The significance of these results to the regulation of N-SMase is discussed.

Animals↗

PubMed1998

The "8-kD" cytoplasmic dynein light chain is required for nuclear migration and for dynein heavy chain localization in Aspergillus nidulans.

The heavy chain of cytoplasmic dynein is required for nuclear migration in Aspergillus nidulans and other fungi. Here we report on a new gene required for nuclear migration, nudG, which encodes a homologue of the "8-kD" cytoplasmic dynein light chain (CDLC). We demonstrate that the temperature sensitive nudG8 mutation inhibits nuclear migration and growth at restrictive temperature. This mutation also inhibits asexual and sexual sporulation, decreases the intracellular concentration of the nudG CDLC protein and causes the cytoplasmic dynein heavy chain to be absent from the mycelial tip, where it is normally located in wild-type mycelia. Coimmunoprecipitation experiments with antibodies against the cytoplasmic dynein heavy chain (CDHC) and the nudG CDLC demonstrated that some fraction of the cytoplasmic dynein light chain is in a protein complex with the CDHC. Sucrose gradient sedimentation analysis, however, showed that not all of the NUDG protein is complexed with the heavy chain. A double mutant carrying a cytoplasmic dynein heavy chain deletion plus a temperature-sensitive nudG mutation grew no more slowly at restrictive temperature than a strain with only the CDHC deletion. This result demonstrates that the effect of the nudG mutation on nuclear migration and growth is mediated through an interaction with the CDHC rather than with some other molecule (e.g., myosin-V) with which the 8-kD CDLC might theoretically interact.

Amino Acid Sequence↗