Biomedical subjects

Q Wu

Publications and source records attributed to Q Wu.

At least 271 records · Page 15Linked to original sources

PubMed1998

[The correlation between P-glycoprotein and multidrug resistance of squamous carcinoma in oral and maxillofacial region].

OBJECTIVE: To study the mechanism of drug resistance of oral carcinoma to chemotherapy. METHODS: 40 cases of squamous carcinoma in the oral and maxillofacial region were examined for the multidrug resistance gene product P-glycoprotein using a monoclonal antibody MRK16. RESULTS: P-glycoprotein was detected in 62.5% of the sample. P-glycoprotein expression was related to the chemotherapy and the degree of differentiation. P-glycoprotein expression was higher in post-chemotherapy group than in unchemotherapy group (P < 0.05). Well differentiated tumors expressed P-glycoprotein more frequently (P < 0.05). P-glycoprotein expression was compared with clinic response to chemotherapy. The accuracy rate of prediction is 75%. CONCLUSION: P-glycoprotein plays an important role in mechanism of multidrug resistance of squamous carcinoma in the oral and maxillofacial region.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

[The histopathological analysis of root fractures of molars with vital pulp].

OBJECTIVE: To analyze the causes of root fractures by examining fractured roots histologically. METHODS: Fractured roots were sectioned for microscopic analysis in conventional histological ways. RESULTS: 1. Among 18 roots cut transversely were 14 flat roots with 2 canals, 2. most of the fractures passed along incremental line in dentine, 3. of the longitudinally sectioned roots, areas of marked resorption were visible on the dentine within the fractures of apical third, and 4. repairs of both soft and hard tissues were observed in the fracture spaces. CONCLUSION: The fractures of roots were associated with morphology of roots and incremental lines in dentine. The repair and cure of fractured roots were not impossible.

Humans↗

PubMed1998

[Examination of anterior proliferative vitreoretinopathy with ultrasound biomicroscopy].

OBJECTIVE: To diagnose anterior proliferative vitreoretinopathy (a-PVR) with ultrasound biomicroscopy (UBM). METHODS: The UBM images of 27 cases (27 eyes) of suspicious a-PVR from cases with retinal detachment with PVR were analyzed and compared with the images of B scan ultrasound and the findings during vitrectomy. RESULTS: UBM diagnosis of a-PVR was found in 20 eyes with retinal circumferential contraction, and in 15 eyes with retinal anterior displacement. A-PVR was not diagnosed by UBM in 7 eyes. UBM images of a-PVR included: the pattern of dots and cords in vitreous proliferation, the echo augmentation and obvious central displacement of the retina with circumferential contraction. Besides, the trough, "angle" and "Z" shaped overlap of the retina were the characteristics of the retinal anterior displacement. CONCLUSION: UBM plays an important role in the clinical diagnosis of a-PVR.

Adolescent↗

PubMed1998

[RP-HPLC method for determination of isorhynchophylline in plasma and its pharmacokinetics in rabbits].

A reversed phase HPLC method for determination of isorhnchophylline (IRHY) in rabbit plasma was developed. A Shimadzu LC-10A liquid chromatograph equipped with a Shimadzu SPD-10A multiwavelength detector and a Chromatopac LC-10A data processor were used. The analytical column was a 4.6 mm x 150 mm CLC-ODS. The mobile phase was a mixture of methanol-water (95:5), the flow rate was 1 ml.min-1. Detection was performed at UV 254 nm. The calibration curve was linear in the range from 0.016 to 16 micrograms.ml-1 with gamma = 0.9990. The lowest detection limit was 0.016 microgram.ml-1. The precision and accuracy of within-day and day-to-day ranged from 3.8% to 6.9%. The recoveries were 80.5% to 85.1%. The drug concentrtion-time curves of IRHY in rabbits after i.v. of 2 mg.kg-1 and 5 mg.kg-1 were shown to fit a two-compartment open model with half-times of 1.32 +/- 0.6 h and 1.25 +/- 0.09 h respectively. The absorption was fast after intraduodenal administration of IRHY (2 mg.kg-1 and 5 mg.kg-1) to rabbits with half-times of 1.75 +/- 0.18 h and 1.26 +/- 0.20 h, respectively. The bioavailability of IRHY was about 42.4% to 69.4%. The results showed that the method was simple and fast. The absorption and elimination were fast atfer intraduodenal administration or i.v. of IRHY to rabbits.

Alkaloids↗

PubMed1998

[Studies on the synthesis and experimental therapeutic effects of metal chlorin on 60Co-irridiated mice].

Pheophorbide a and pyropheophorbide a were prepared by acid degradation of crude chlorophylls isolated from silkworm excrement. Pheophorbide a was further degraded to chlorin e6 monomethyl ester in alkaline methanol in absence of oxygen. Pure purpurin 18 was directly prepared from alkali degradation of silkworm excrement crude chlorophylls in presence of oxygen. Nine chlorin complexes of Co, Cu and Zn were synthesized for the first time. Preliminary pharmacological tests showed that chlorin e6 monomethyl ester copper complex(7) could increase survival and prolong the surviving time of 60Co-irridiated mice significantly.

Animals↗

PubMed1998

[In vitro sensitivity of oral gram-negative bacteria to the bactericidal activity of defensins].

Oral gram-negative bacteria, including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Capnocytophaga sputigena, Provotella intermedius, Provotella melaninogenicus, have been associated with destructive periodontal infection. An ultrasensitive antibacterial assay was applied to determine the sensitivity of a battery of oral gram-negative bacteria to the bactericidal effects of the isolated human neutrophil defensins (HNP) and two kinds of rabbit defensins NP1 and NP2. All species tested were killed by HNP, NP1 and NP2 except that porphyromonas gingivalis was resistant to HNP. However, there was strain-to-strain variation in sensitivity. It was concluded that the oral gram-negative bacteria were sensitive to the cidal mechanism involved in defensinmediated bacterial killing.

Aggregatibacter actinomycetemcomitans↗

PubMed1998

The immunological studies on proliferative intraocular disorders: investigation of activated lymphocytes, macrophages and HLA-DR.

PURPOSE: To investigate whether activated B lymphocytes (CD23), activated T lymphocytes (CD25), macrophages (CD68) and human leucocyte antigen class II antigen (HLA-DR) were existed in epiretinal membranes (ERMs) and subretinal membranes (SRMs) of proliferative intraocular disorders (PID). METHODS: Twenty specimens of ERMs from rhegmatogenous retinal detachment with proliferative vitreoretinopathy (PVR), traumatic PVR and secondary traction retinal detachment, and two specimens of SRMs from rhegmatogenous retinal detachment with PVR and traumatic PRV were studied using immunohistochemical staining. RESULTS: CD68 and HLA-DR were found in all specimens, CD23 and CD25 in 4 cases of ERMs and in 1 case of SRMs, respectively. CONCLUSIONS: 1. The ERMs and SRMs of different etiology shared a common basis of inflammation and immunopathology. 2. There would be secondary cellular and humoral immunity in the ERMs and the SRMs of PID.

Antigens, CD↗

PubMed1998

[Chemical shifts of CrKbeta peaks in XRF spectra by Si(Li) spectrometry].

The energies of CrKbeta X-Rays in metel Cr, Cr2Os and K2CrO4, which are excited respectively by gamma-ray 59.6keV from radioactive source 241Am, have been measured by Si(Li) spectrometry. It is shown in the experiment that the peak of CrKbeta X-ray in K2CrO4 shifts 2.12 +/- 0.27eV compared to that in metel Cr.

English Abstract↗

PubMed1998

[Simultaneous determination of zinc, cadmium and lead chelated by porphyrin with partial least squares fluorimetry].

The fluorescence spectra of super-highly sensitive chelate systems containing multicomponent metal porphyrins are analysed by partial least squares method, and a computerized analysis for the simultaneous determination of zinc, cadmium and lead is developed. Zinc, cadmium and lead can quantitatively combine with meso-tetrakis-(4-methoxyphenyl)-porphyrin in a strong base medium and in the presence of Tween-80 when they are heated for 30 min in a boiling water-bath. The proposed method has been applied to the simultane ous determination of zinc, cadmium and lead in artificial and environmental water samples, and the recovery ratios are in the range of 93.2-107%.

English Abstract↗

PubMed1997

A nitrite biosensor based on a maltose binding protein nitrite reductase fusion immobilized on an electropolymerized film of a pyrrole-derived bipyridinium.

The preparation and electrochemical characterization of glassy carbon electrodes (GCEs) modified with electropolymerized films of the cation N-(3-pyrrol-1-yl-propyl)-4,4'-bipyridine (PPB) are described. The behavior of a new biosensor, which exhibits a high catalytic activity for nitrite reduction and which consists of a maltose binding protein nitrite reductase fusion (MBP-Nir) immobilized on an electropolymerized film of PPB as an electrocatalyst, is also described. The insoluble perchlorate salt of the poly(benzyl viologen) dication was used to immobilize MBP-Nir onto an electrode previously modified with an electropolymerized film of PPB. The electropolymerized film of PPB on the GCE is redox active and exhibits special electron-transfer properties toward the MBP-Nir layer but not toward Nir (Nir without MBP fusion attached), suggesting an intimate interaction between the PPB film and the MBP-Nir layer. The kinetics of the catalytic reaction between the biosensor and nitrite anion were characterized using cyclic voltammetry and rotated disk electrode techniques, and a value of (4.6 +/- 0.5) x 10(3) M-1 S-1 was obtained for the rate constant.

Biosensing Techniques↗

PubMed1997

Planning, delivery, and quality assurance of intensity-modulated radiotherapy using dynamic multileaf collimator: a strategy for large-scale implementation for the treatment of carcinoma of the prostate.

PURPOSE: To improve the local control of patients with adenocarcinoma of the prostate we have implemented intensity modulated radiation therapy (IMRT) to deliver a prescribed dose of 81 Gy. This method is based on inverse planning and the use of dynamic multileaf collimators (DMLC). Because IMRT is a new modality, a major emphasis was on the quality assurance of each component of the process and on patient safety. In this article we describe in detail our procedures and quality assurance program. METHODS AND MATERIALS: Using an inverse algorithm, we have developed a treatment plan consisting five intensity-modulated (IM) photon fields that are delivered with DMLC. In the planning stage, the planner specifies the number of beams and their directions, and the desired doses for the target, the normal organs and the "overlap" regions. Then, the inverse algorithm designs intensity profiles that best meet the specified criteria. A second algorithm determines the leaf motion that would produce the designed intensity pattern and produces a DMLC file as input to the MLC control computer. Our quality assurance program for the planning and treatment delivery process includes the following components: 1) verification of the DMLC field boundary on localization port film, 2) verification that the leaf motion of the DMLC file produces the planned dose distribution (with an independent calculation), 3) comparison of dose distribution produced by DMLC in a flat phantom with that calculated by the treatment planning computer for the same experimental condition, 4) comparison of the planned leaf motions with that implemented for the treatment (as recorded on the MLC log files), 5) confirmation of the initial and final positions of the MLC for each field by a record-and-verify system, and 6) in vivo dose measurements. RESULTS: Using a five-field IMRT plan we have customized dose distribution to conform to and deliver 81 Gy to the PTV. In addition, in the overlap regions between the PTV and the rectum, and between the PTV and the bladder, the dose is kept within the tolerance of the respective organs. Our QA checks show acceptable agreement between the planned and the implemented leaf motions. Correspondingly, film and TLD dosimetry indicates that doses delivered agrees with the planned dose to within 2%. As of September 15, 1996, we have treated eight patients to 81 Gy with IMRT. CONCLUSION: For complex planning problems where the surrounding normal tissues place severe constraints on the prescription dose, IMRT provides a powerful and efficient solution. Given a comprehensive and rigorous quality-assurance program, the intensity-modulated fields can be efficaciously and accurately delivered using DMLC. IMRT treatment is now ready for routine implementation on a large scale in our clinic.

Adenocarcinoma↗

PubMed1997

Receptor-associated constitutive protein tyrosine phosphatase activity controls the kinase function of JAK1.

Exposure of cells to protein tyrosine phosphatase (PTP) inhibitors causes an increase in the phosphotyrosine content of many cellular proteins. However, the level at which the primary signaling event is affected is still unclear. We show that Jaks are activated by tyrosine phosphorylation in cells that are briefly exposed to the PTP inhibitor pervanadate (PV), resulting in tyrosine phosphorylation and functional activation of Stat6 (in addition to other Stats). Mutant cell lines that lack Jak1 activity fail to support PV-mediated [or interleukin 4 (IL-4)-dependent] activation of Stat6 but can be rescued by complementation with functional Jak1. The docking sites for both Jak1 and Stat6 reside in the cytoplasmic domain of the IL-4 receptor alpha-chain (IL-4Ralpha). The glioblastoma-derived cell lines T98G, GRE, and M007, which do not express the IL-4Ralpha chain, fail to support Stat6 activation in response to either IL-4 or PV. Complementation of T98G cells with the IL-4Ralpha restores both PV-mediated and IL-4-dependent Stat6 activation. Murine L929 cells, which do not express the gamma common chain of the IL-4 receptor, support PV-mediated but not IL-4-dependent Stat6 activation. Thus, Stat6 activation by PV is an IL-4Ralpha-mediated, Jak1-dependent event that is independent of receptor dimerization. We propose that receptor-associated constitutive PTP activity functions to down-regulate persistent, receptor-linked kinase activity. Inhibition or deletion of PTP activity results in constitutive activation of cytokine signaling pathways.

Amino Acid Sequence↗

PubMed1997

High-resolution genetic map of the human glutamyl aminopeptidase gene (ENPEP).

The murine B-lymphocyte differentiation antigen BP-1/6C3 has been identified as glutamyl aminopeptidase (EAP), the gene symbol for which is ENPEP. Using genomic DNA encoding for human EAP as a probe, we identified the ENPEP gene location on human chromosome 4q25 by polymerase chain reaction analysis of a human/rodent somatic cell hybrid mapping panel and by fluorescence in situ hybridization. Using a radiation hybrid panel, the gene order around ENPEP was determined to be centromere-D4S1236-(570 kb)-ENPEP-(210 kb)-D4S262-(270 kb)-D4S953-(270 kb)-D4S474-(570 kb)-IF. The linkage of ENPEP to complement factor I (IF) confirms the human chromosome band 4q25 localization predicted from the chromosomal location of murine ENPEP. Human ENPEP thus provides an additional marker for the long arm of chromosome 4 that should facilitate studies of this genomic region.

Aminopeptidases↗

PubMed1997

The influence of x-ray energy on lung dose uniformity in total-body irradiation.

PURPOSE: In this study we examine the influence of x-ray energy on the uniformity of the dose within the lung in total-body irradiation treatments in which partial transmission blocks are used to control the lung dose. METHODS AND MATERIALS: A solid water phantom with a cork insert to simulate a lung was irradiated by x-rays with energies of either 6, 10, or 18 MV. The source to phantom distance was 3.9 meters. The cork insert was either 10 cm wide or 6 cm wide. Partial transmission blocks with transmission factors of 50% were placed anterior to the cork insert. The blocks were either 8 or 4 cm in width. Kodak XV-2 film was placed in the midline of the phantom to record the dose. Midplane dose profiles were measured with a densitometer. RESULTS: For the 10 cm wide cork insert the uniformity of the dose over 80% of the block width varied from 6.6% for the 6 MV x-rays to 12.2% for the 18 MV x-rays. For the 6 cm wide cork insert the uniformity was comparable for all three x-ray energies, but for 18 MV the central dose increased by 9.4% compared to the 10 cm wide insert. CONCLUSION: Many factors must be considered in optimizing the dose for total-body irradiation. This study suggests that for AP/PA techniques lung dose uniformity is superior with 6 MV irradiation. The blanket recommendation that the highest x-ray energy be used in TBI is not valid for all situations.

Lung↗

PubMed1997

Effects of receptor class- and subtype-selective retinoids and an apoptosis-inducing retinoid on the adherent growth of the NIH:OVCAR-3 ovarian cancer cell line in culture.

Comparison of the adherent growth inhibition of NIH:OVCAR-3 ovarian cancer cells by retinoid receptor class-selective and subtype-selective compounds with their receptor binding affinities and transcriptional activation activities indicated no correlation for RAR alpha and RAR gamma although both receptors are present. Retinoids that activated RXR alpha inhibited cell growth in the range as all-trans-retinoic acid and 9-cis-retinoic acid. The most potent inhibitor was 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalenecarboxylic acid (AHPN), which has been found to inhibit breast and lung cancer and leukemia cell growth and induce cancer cell apoptosis through a pathway independent of the retinoid receptors.

Apoptosis↗

PubMed1997

Modulation of retinoic acid sensitivity in lung cancer cells through dynamic balance of orphan receptors nur77 and COUP-TF and their heterodimerization.

The diverse function of retinoic acid (RA) is mediated by its nuclear receptors, the retinoic acid receptors (RARs) and retinoid X receptors (RXRs). However, the RA response is often lost in cancer cells that express the receptors. Previously, it was demonstrated that the RA response is regulated by the COUP-TF orphan receptors. Here, we present evidence that nur77, another orphan receptor whose expression is highly induced by phorbol esters and growth factors, is involved in modulation of the RA response. Expression of nur77 enhances ligand-independent transactivation of RA response elements (RAREs) and desensitizes their RA responsiveness. Conversely, expression of COUP-TF sensitizes RA responsiveness of RAREs by repressing their basal transactivation activity. Unlike the effect of COUP-TFs, the function of nur77 does not require direct binding of nur77 to the RAREs, but is through interaction between nur77 and COUP-TFs. The interaction occurs in solution and results in inhibition of COUP-TF RARE binding and transcriptional activity. Unlike other nuclear receptors, a large portion of the carboxy-terminal end of nur77 is not required for its interaction with COUP-TF. In human lung cancer cell lines, COUP-TF is highly expressed in RA-sensitive cell lines while nur77 expression is associated with RA resistance. Stable expression of COUP-TF in nur77-positive, RA-resistant lung cancer cells enhances the inducibility of RARbeta gene expression and growth inhibition by RA. These observations demonstrate that a dynamic equilibrium between orphan receptors nur77 and COUP-TF, through their heterodimerization that regulates COUP-TF RARE binding, is critical for RA responsiveness of human lung cancer cells.

Animals↗

PubMed1997

Surgical treatment of dissecting aneurysm of the interventricular septum.

Two extremely rare cases of dissecting aneurysm of the interventricular septum associated with aortic incompetence are reported. One was complicated with an aneurysm of the left coronary sinus of Valsalva, and the other may have been the result of trauma. Surgical operation involved resection or repair of the aneurysm and replacement of the aortic valve. Both patients recovered uneventfully. Early diagnosis and surgical intervention are emphasized.

Adult↗

PubMed1997

Isolation of the cDNAs encoding (+)6a-hydroxymaackiain 3-O-methyltransferase, the terminal step for the synthesis of the phytoalexin pisatin in Pisum sativum.

Pisatin is the major phytoalexin produced by pea upon microbial infection. The enzyme that catalyzes the terminal step in the pisatin biosynthetic pathway is (+)6a-hydroxymaackiain 3-O-methyltransferase (HMM). We report here the isolation and characterization of two HMM cDNA clones (pHMM1 and pHMM2) made from RNA obtained from Nectria haematococca-infected pea tissue. The two clones were confirmed to encode HMM activity by heterologous expression in Escherichia coli. The substrate specificity of the methyltransferases in E. coli was similar to the activity detected in CuCl2-treated pea tissue. Nucleotide sequence analysis of Hmm1 and Hmm2 revealed an open reading frame of 1080 bp and 360 amino acid residues which would encode 40.36 kda and 40.41 kDa polypeptides, respectively. The deduced amino acid sequence of HMM1 has 95.8% identity to HMM2, 40.6% identity to Zrp4, a putative O-methyltransferase (OMT) in maize root, and 39.1% to pBH72-F1, a putative OMT induced in barley by fungal pathogens or UV light. Comparison of the deduced amino acid sequences of the cDNA clones to OMTs from other higher plants identified the binding sites of S-adenosylmethionine (AdoMet). Southern blot analysis showed two closely linked genes with strong homology to Hmm in the pea genome.

Amino Acid Sequence↗