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Biomedical subjects

W Qian

Publications and source records attributed to W Qian.

At least 37 records · Page 2Linked to original sources
PubMed2001

A comparative study of third-order nonlinear optical properties of silver phenylacetylide and related compounds via ultrafast optical Kerr effect measurements.

A comparative study of the third-order nonlinear optical properties, via the newly developed heterodyned optical Kerr effect (OHD-OKE) measurements, of silver phenylacetylide and related compounds is reported. [AgC[triple bond]CC(6)H(5)](n) (1) was found to exhibit efficient third-order nonlinear optical susceptibility chi((3)) of 2.4 x 10(-14) esu, and second hyperpolarizability gamma of 9.07 x 10(-32) esu. These results are compared with those of two related silver phenylacetylide compounds, namely, a double salt, (silver phenylacetylide).(silver tert-butylthiolate) [AgC[triple bond]CC(6)H(5).AgS(t-C(4)H(9))](n) complex (2), and a cluster, triphenylphosphine silver phenylacetylide tetramer, [(C(6)H(5))(3)PAgC[triple bond]CC(6)H(5)](4) (3), as well as that of the related organic polymer polyphenylacetylene (4). These four compounds represent different types of phenylacetylide derivatives: 1 is an organometallic polymer, 2 a polymeric double salt, 3 a discrete metal cluster, and 4 an organic polymer. It was found that the third-order optical nonlinear response was enhanced by the incorporation of silver d electrons into the delocalized conjugated organic pi system, and its magnitude is highly dependent upon the extent of the pi delocalization. Specifically, the relative magnitudes of chi((3)) and gamma follow the order silver phenylacetylide polymer (1) > (silver phenylacetylide).(silver tert-butylthiolate) double salt (2) > polyphenylacetylene polymer (4) > tetrameric (triphenylphosphine silver phenylacetylide)(4) cluster (3). The observed trend may be attributed to the decreasing length of pi conjugation. It is interesting to note that the incorporation of Ag(I) into the polymeric framework of polyphenylacetylene enhances the chi((3)) by 25-fold for the same degree of polymerization (n = 7). The signs of chi((3)) and gamma, which are related to the response mechanisms, were found to be solvent dependent.

Journal Article↗
PubMed2001

Human wig-1, a p53 target gene that encodes a growth inhibitory zinc finger protein.

We previously identified a novel p53-induced mouse gene, wig-1, that encodes a 290 amino acid zinc finger protein (Varmeh-Ziaie et al., 1997). Here we have identified and characterized the human homolog of mouse wig-1. The human wig-1 protein is 87% identical to the mouse protein and contains three zinc finger domains and a putative nuclear localization signal. Human wig-1 mRNA and protein is induced following activation of wild type p53 expression in our BL41-ts p53 Burkitt lymphoma cells. Wig-1 is also induced in MCF7 cells following treatment with the DNA-damaging agent mitomycin C. Northern blotting detected low levels of wig-1 mRNA in normal human tissues. Fluorescence in situ hybridization mapped wig-1 to human chromosome 3q26.3-27. FLAG-tagged human wig-1 localizes to the nucleus. Ectopic overexpression of human wig-1 inhibits tumor cell growth in a colony formation assay. These results suggest that human wig-1 has a role in the p53-dependent growth regulatory pathway.

Amino Acid Sequence↗
PubMed2001

Fatty acids inhibit growth-factor-induced diacylglycerol kinase alpha activation in vascular smooth-muscle cells.

We have previously shown that unsaturated fatty acids amplify platelet-derived-growth-factor (PDGF)-induced protein kinase C (PKC) activation in vascular smooth-muscle cells (VSMCs). Diacylglycerol-induced PKC activation is normally terminated by diacylglycerol kinases (DGKs). We thus hypothesized that fatty acids act by inhibiting a DGK. Fractionation of VSMC extracts demonstrated that the DGK alpha isoform was the major DGK activity present. PDGF markedly increased the DGK activity of cultured cells. An inhibitor selective for the DGK alpha isoform, R59949 [3-[2-[4-(bis-(4-fluorophenyl)methylene]piperidin-1-yl)ethyl]-2,3-dihydro-2-thioxo-4(1H)-quinazolinone], abolished the growth-factor-induced increase in DGK activity, but had little effect on basal activity. PDGF thus selectively activates DGKalpha. Epidermal growth factor and alpha-thrombin stimulated total DGK activity similarly to PDGF. Activation by epidermal growth factor was sensitive to R59949, again suggesting involvement of DGKalpha. However, the alpha-thrombin-induced activity was unaffected by this agent. Unsaturated fatty acids inhibited growth-factor-induced DGKalpha activation, but had no effect on basal activity. Fatty acids also amplified the PDGF-induced increase in cell diacylglycerol content. These results indicate that inhibition of DGKalpha contributes to fatty-acid-induced amplification of PKC activation. Increased levels of fatty acids in diabetes may thus contribute to chronic PKC activation associated with this disorder.

Animals↗
PubMed2001

High-dose therapy and autologous stem-cell transplantation versus conventional-dose consolidation/maintenance therapy as postremission therapy for adult patients with lymphoblastic lymphoma: results of a randomized trial of the European Group for Blood and Marrow Transplantation and the United Kingdom Lymphoma Group.

PURPOSE: To determine whether a combination of high-dose therapy and autologous stem-cell transplantation (ASCT) is superior to conventional-dose consolidation and maintenance chemotherapy as postremission therapy in adults with lymphoblastic lymphoma. PATIENTS AND METHODS: One hundred nineteen patients were entered onto this prospective randomized trial from 37 centers. Patients received standard remission induction therapy, and responding patients were randomized either to continue with a conventional consolidation/maintenance protocol (CC) or to receive high-dose therapy and ASCT. In some centers, patients with HLA-identical sibling donors were registered on the trial but proceeded to allogeneic bone marrow transplantation (BMT) without randomization. RESULTS: Of the 119 patients entered, 111 were assessable for response to induction therapy. The overall response rate was 82% (56% complete response, 26% partial response). Of the 98 patients eligible for randomization, 65 were randomized, 31 to ASCT and 34 to CC. Reasons for failure to randomize included patient refusal (12 patients), early progression or death on induction therapy (eight patients), excessive toxicity of induction regimen (six patients), and elective allogeneic BMT (12 patients). With a median follow-up of 37 months, the actuarial 3-year relapse-free survival rate is 24% for the CC arm and 55% for the ASCT arm (hazards ratio = 0.55 in favor of the ASCT arm; 95% confidence interval [CI], 0.29 to 1.04; P =.065). The corresponding figures for overall survival are 45% and 56%, respectively (hazards ratio = 0.87 in favor of the ASCT arm; 95% CI, 0.42 to 1.81; P =.71). CONCLUSION: The use of ASCT in adults with lymphoblastic lymphoma in first remission produced a trend for improved relapse-free survival but did not improve overall survival compared with conventional-dose therapy in this small randomized trial.

Adolescent↗
PubMed2001

Digital mammography: wavelet transform and Kalman-filtering neural network in mass segmentation and detection.

RATIONALE AND OBJECTIVES: The authors developed a new adaptive module to improve their computer-assisted diagnostic (CAD) method for mass segmentation and classification. The goal was an adaptive module that used a novel four-channel wavelet transform with neural network rather than a two-channel wavelet transform with manual subimage selection. The four-channel wavelet transform is used for image decomposition and reconstruction, and a novel Kalman-filtering neural network is used for adaptive subimage selection. MATERIALS AND METHODS: The adaptive CAD module was compared with the nonadaptive module by comparing receiver operating characteristic curves for the whole CAD system. An image database containing 800 regions of interest enclosing all mass types and normal tissues was used for the relative comparison of system performance, with electronic ground truth established in advance. RESULTS: The receiver operating characteristic curves yield Az values of 0.93 and 0.86 with and without the adaptive module respectively, suggesting that overall CAD performance is improved with the adaptive module. CONCLUSION: The results of this study confirm the importance of using a new class of adaptive CAD methods that allow a more generalized application for larger image databases or images generated from different sensors or by means of direct x-ray detection, as required for clinical trials.

Humans↗
PubMed2001

Naphthoquinone-Induced cataract in mice: possible involvement of Ca2+ release and calpain activation.

N-acetyl-p-benzoquinone imine (NAPQI), a semiquinone metabolite of acetaminophen, produces cataract in mice. Naphthalene is biotransformed to the cataractogenic metabolite 1,2-naphthoquinone (NQ). Intracameral injection of NAPQI elicits a rapid increase in free intracellular Ca2+ in the lens epithelium and calpain activation before lens opacification begins. In order to test whether the cellular response is a common feature of quinone-induced cataracts, we injected in this work 1,2-naphthoquinone (NA) in the anterior chamber of mouse eye and followed cellular responses in the lens prior to opacity development. A marked rise in free intracellular Ca2+ in the lens epithelium and concurrent activation of calpain were observed within 1 hr after NQ injection preceding lens opacity development. These results support the suggestion that Ca2+ release and calpain activation are involved in the mechanism of quinone-induced cataractogenesis.

Animals↗
PubMed2001

Nasal nitric oxide and the nasal cycle.

OBJECTIVES: To establish the relationship between nasal patency and the nitric oxide (NO) concentration in the nasal airways. METHODS: Unilateral nasal NO concentration (n = 11) and inhaled nasal NO concentration at oropharynx (n = 9) were measured in healthy adult volunteers. Subjects breathed normally through the nose with a known resistance (ranged from none to total occlusion) placed in one nostril. In a subgroup (n = 7), the unilateral nasal NO concentrations were determined with nasal cavity congestion induced by lateral decubitus. RESULTS: When the added nasal resistance was less than 6 cm H(2)0 per liter per second, the peak NO concentrations in the nose remained below 80 parts per billion (ppb). Thereafter, the higher the resistance, the greater the NO concentration. It was up to 1109.7 ppb when the front nostril was totally occluded. There was no correlation between oropharyngeal NO concentrations and resistance in the front of the nose (r = 0.4). There was a significantly negative correlation between nasal cavity volumes and nasal NO concentrations (r = -0.8, P <.001). CONCLUSIONS: Increases in nasal resistance to levels encountered in the nasal cycle and in recumbency augments the NO concentration within the obstructed side of the nose. Although that within the nose changes with patency, the NO concentration is constant down to the lower airways. The modulation role of the upper airways to the inhaled NO concentration remains unclear.

Adult↗
PubMed2001

A new method for the remote collection of nasal and exhaled nitric oxide.

STUDY OBJECTIVES: The present study introduces a method that has been developed to improve the remote collection and transportation of gas samples from the nose and lungs. DESIGN: Assessment of agreement between two methods of clinical measurements. SETTING: Noninvasive exhaled gas measurement at a respiratory research laboratory. PARTICIPANTS: Ten nonsmoking adult volunteers (median age, 44 years; age range, 33 to 53 years; men, 6; women, 4) were recruited. MEASUREMENTS AND RESULTS: Exhaled nitric oxide (ENO) and nasal nitric oxide (NNO) outputs were measured directly (on-line) and remotely (off-line). With the velum closed, lung air was exhaled at fixed flows (ie, 6, 8, and 10 L/min) (ENO) or room-air was aspirated through the nose in series at one fixed flow (ie, 5 to 8 L/min) (NNO). The off-line nitric oxide (NO) measurements were achieved by a gas collection tube system, which consisted of a flow control unit, a tube reservoir with one-way valves at both ends, and an interrupter valve allowing the trapping of gas inside the tube and eliminating the inclusion of "dead space." After clamping, the reservoir may store and transport the gas samples for delayed analysis. The coefficient of variation of three consecutive NO measurements was < 3% for both on-line and off-line ENO and NNO. The correlations between on-line and off-line measurements in both ENO and NNO outputs were high (r = 0.99; R(2) = 0.99), and, unlike previous studies using bag-collection, the ENO outputs for on-line and off-line measurements were in good agreement (Bland-Altman test) at all flows tested. CONCLUSIONS: The tube gas collection system eliminates the dead space and contamination during the gas sampling and permits the cost-effective and reliable off-line collection of both nasal and exhaled gas samples.

Adult↗
PubMed2001

Renal and hepatic toxicity of trichloroethylene and its glutathione-derived metabolites in rats and mice: sex-, species-, and tissue-dependent differences.

Acute cytotoxicity (lactate dehydrogenase release) of trichloroethylene (TRI), S-(1,2-dichlorovinyl)glutathione (DCVG), and S-(1,2-dichlorovinyl)-L-cysteine (DCVC) in freshly isolated renal cortical cells and hepatocytes from male and female rats was evaluated to test the hypothesis that the assay provides a valid indicator of sex- and tissue-dependent differences in sensitivity to TRI and its metabolites. We then determined mitochondrial toxicity (inhibition of state-3 and/or stimulation of state-4 respiration) in renal cortical and hepatic mitochondria from male and female rats and mice to assess sex-, tissue-, and species-dependent susceptibility. TRI was moderately cytotoxic in renal cells from male rats but was nontoxic in renal cells from female rats or hepatocytes from male or female rats. Acute cytotoxicity of both DCVG and DCVC was greater in renal cells from male rats than in renal cells from female rats. Although DCVC does not target the liver in vivo, it was a very potent hepatotoxicant in vitro. Mitochondrial toxicity in kidney and liver showed similar patterns, with mitochondria from male rats being more sensitive than mitochondria from female rats; order of potency was DCVC > DCVG >> TRI. State-3 respiration in mitochondria from mice was also inhibited, but the patterns and relative sensitivities differed from those in mitochondria from rats. Renal and hepatic mitochondria from mice were less sensitive than corresponding mitochondria from rats and renal mitochondria from female mice were significantly more sensitive than renal mitochondria from male mice. Thus, many of the species-, sex-, and tissue-dependent differences in toxicity observed in vivo are also observed in vitro.

Animals↗
PubMed2001

[Analyses of population genetic structure by using dominant markers].

Dominant markers tend to under-estimate the amount of genetic diversity relative to codominant systems when applying in population genetics. In order to compare various existing methods for analysis of genetic structure, RAPD markers were used to detect genetic variability of 5 populations of Oryza granulata from China. The results indicated that both Shannon index of diversity and Nei gene diversity were superior to percentage of polymorphic bands (PPB) because the latter lacked of ability to describe frequency difference of polymorphic bands. Mantel test showed significant relation (r > 0.95, t > t0.01) among matrice of 17 different genetic similarities, which indicated that all of them could be used in analysis of genetic relations of individuals of Oryza granulata. Both AMOVA analysis based on phi st distance and analysis of Nei's distance showed consistent results in defining relationship among the 5 populations, and Lynch-Milligan pruning should be used to improve the estimation of population parameters. All of AMOVA, Gst and Shannon diversity analyses obtained similar results with majority of genetic variation occurring between Yunnan and Hainan, and low levels of genetic diversity resided within regions and populations.

Genetic Markers↗
PubMed2001

[A prospective study on the association between underweight and mortality from all cause].

OBJECTIVE: To explore the association between underweight and mortality from all cause. METHOD: We examined the relationship of underweight and mortality among subjects who participated in the survey of cardiovascular risk factors (in 1984-1986 and in 1992). Relative Risks (RRs) were estimated from the COX proportional hazard model by using a BMI between 18.5-24.9 kg/m2 as reference category. RESULTS: During an average 12.40 years follow-up, we documented 307 deaths of which 158 were from cancer, 93 from cardiovascular diseases, and 56 from other causes. We observed a L-shaped relation between BMI and overall mortality. (P for trend < 0.01); In multivariated analyses, we found that the RR of mortality for a BMI of < 18.5 kg/m2 was 1.58 (95% CI 1.16-2.14) as compared with the risk among subjects with BMI of 18.5-24.9 kg/m2. The RR of overall mortality among subjects with BMI of < 18.5 kg/m2 was still significant after the exclusion of subjects who died from cancers during the first five years follow-up. CONCLUSION: Total mortality was increased among underweight people, and this association can not been completely explained by smoking and early deaths from cancer.

Adult↗
PubMed2001

Apolipoprotein E polymorphism in the early onset of coronary heart disease.

OBJECTIVE: To assess the relationship between apolipoprotein E (apoE) polymorphism and the early onset of coronary heart disease (CHD) and the effect of apoE on lipids and lipoproteins in healthy Chinese subjects. METHODS: Sixty-eight patients with CHD younger than 55 years (CHD1), 136 patients with CHD older than 65 years (CHD2), and 136 healthy subjects were enrolled, and their plasma levels of triglyceride (TG), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) were determined. The apoE genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: apoE 3/4 genotype and E4 allele frequency in the CHD1 group were higher than those in the CHD2 group and healthy subjects, while no differences were found between CHD2 and healthy subjects. Meanwhile, the plasma levels of TC and low density lipoprotein cholesterol (LDL-C) were higher in the CHD2 group than in both CHD1 group and healthy subjects. Each apoE isoprotein has variable TC and LDL-C levels that is E2 (E2/2 + E2/3) < E3(E3/3) < E4(E4/4 + E3/4). CONCLUSION: apoE is one of the genetic factors that affect TC and LDL-C levels, and apoE 4 has a very close relation to CHD, suggesting that apoE 4 is an independent genetic factor of the early onset of CHD.

Adult↗
PubMed2001

[Combination of mycophenolate mofetil with cyclosporine A and methotrexate as acute GVHD prophylaxis after unrelated donor allogeneic bone marrow transplantation].

OBJECTIVE: To evaluate the efficacy and safety of mycophenolate mofetil (MMF) in combination with cyclosporine A (CsA) and methotrexate (MTX) for prevention of acute graft versus host disease (GVHD) after unrelated donor allogeneic bone marrow transplantation (allo-BMT). METHOD: Twelve cases of unrelated donor allo-BMT were evaluated in a single center trial. The acute GVHD was prevented with 1 g MMF daily in addition to CsA 3 mg x kg(-1) x (-1) and MTX 10 - 15 mg at post BMT day1, day3, day6 and day11. RESULTS: Acute GVHD was found in one case (Grade IV) at the seventh day and two cases (Grade II) at the tenth day and seventeenth day after BMT. These patients were treated with a combination of MMF, methyprednisolone and CsA. The common adverse hematologic events of MMF was leukopenia. CONCLUSION: The preliminary study showed that MMF could be used effectively and safely for prevention of acute GVHD in unrelated donor allo-BMT.

Acute Disease↗
PubMed2001

[Aminopeptidase inhibitor Bestatin induces HL-60 cell apoptosis through activating caspase 3].

OBJECTIVE: To study the variation and significance of caspase 3 activity in the process of amino-peptidase inhibitor--bestatin (BS) inducing human leukemic cell apoptosis. METHODS: Cell apoptosis was evaluated by light microscopy, TUNEL labeling and flow cytometry (FCM). Caspase 3 activity was detected by colorimetry. The mitochondrial transmembrane potentials (DeltaPsi(m)) were detected by Rhodamine123 staining. RESULTS: The apoptotic morphology, apoptotic peak on FCM and positive Annexin V(FITC) on cell membrane showed that BS could induce HL-60 cell apoptosis in a dose- and time-dependent manner. Caspase 3 activity was significantly higher in the apoptotic cells than in control cells. The apoptosis induced by BS was inhibited by AC-DEVD-CHO. The DeltaPsi(m) of cells treated with BS declined. CONCLUSION: BS induces apoptosis of human acute leukemic cells through activation of caspase 3.

Aminopeptidases↗
PubMed2001

[Pyruvate oxidase gene from Streptococcus sanguis: molecular cloning and sequence analysis of the gene].

OBJECTIVE: To clone and sequence the gene of pyruvate oxidase (Sopox) from Streptococcus sanguis. METHODS: The PCR primers for Sopox gene were designed and synthesized according to the sequence of pyruvate oxidase (spxB) gene of S. pneumonia. The amplified PCR product was cloned into pUC18 and then subcloned into M13mp18 and M13mp19. The DNA sequence of the gene was analyzed. RESULTS: Sopox gene was successfully amplified from S. sanguis ATCC10557. The nucleotide sequence of the whole gene was revealed to be 1788 base pairs with one open reading frame coding pyruvate oxidase with 591 amino acid residuals. CONCLUSION: The clone and DNA sequence of Sopox gene were obtained which could serve as a foundation on which to elucidate the molecular mechanisms of hydrogen peroxide production and its regulation by oral streptococci.

Base Sequence↗
PubMed2000

A domain with homology to neuronal calcium sensors is required for calcium-dependent activation of diacylglycerol kinase alpha.

Diacylglycerol kinases (DGKs) phosphorylate diacylglycerol produced during stimulus-induced phosphoinositide turnover and attenuate protein kinase C activation. Diacylglycerol kinase alpha is an 82-kDa DGK isoform that is activated in vitro by Ca(2+). The DGK alpha regulatory region includes tandem C1 protein kinase C homology domains and Ca(2+)-binding EF hand motifs. It also contains an N-terminal recoverin homology (RVH) domain that is related to the N termini of the recoverin family of neuronal calcium sensors. To probe the structural basis of Ca(2+) regulation, we expressed a series of DGK alpha deletions spanning its regulatory domain in COS-1 cells. Deletion of the RVH domain resulted in loss of Ca(2+)-dependent activation. Further deletion of the EF hands resulted in a constitutively active enzyme, suggesting that sequences in or near the EF hands are sufficient for autoinhibition. Binding of Ca(2+) to the EF hands protected sites within both the RVH domain and EF hands from trypsin cleavage and increased the phenyl-Sepharose binding of a recombinant DGK alpha fragment that included both the RVH domain and EF hands. These observations suggested that Ca(2+) elicits a concerted conformational change of these two domains. A cationic amphiphile, octadecyltrimethylammonium chloride, also activated DGK alpha. As with Ca(2+), this activation required the RVH domain. However, this agent did not protect the EF hands and RVH domain from trypsin cleavage. These findings indicate that the EF hands and RVH domain act as a functional unit during Ca(2+)-induced DGK alpha activation.

Amino Acid Sequence↗
PubMed2000

Analysis of messy longitudinal data from a randomized clinical trial. MRC Lung Cancer Working Party.

The randomized clinical trial, LU19, conducted by the Medical Research Council Lung Cancer Working Party, was designed to compare ACE (doxorubicin, cyclophosphamide and etoposide) chemotherapy plus G-CSF (granulocyte colony-stimulating factor) at 2-week intervals versus ACE chemotherapy alone at standard 3-week intervals in patients with small-cell lung cancer. This trial investigated whether more intensive administration of ACE would improve overall survival and affect the quality of life of patients. The report on overall survival and other outcome measures will be published in the Journal of Clinical Oncology. In this paper we focus on methods of analysing aspects of data reflecting quality of life. Twelve symptoms of lung cancer and its treatment - cough, haemoptysis, pain, nausea, vomiting, hoarse voice, sore mouth, rash, lethargy, lack of appetite, alopecia, and dysphagia - were scheduled to be assessed on seven occasions for the ACE arm and on eight occasions for the ACE+G-CSF arm by clinicians during the first 18 weeks of the treatment period. However, in practice the number of assessment forms completed per patient ranged from 1 to 9, and assessment time-points were very different from those planned. These 'messy' longitudinal data are explored by both a summary measure approach, in which experience of a symptom is summarized by a single value, and an extensive model-based statistical approach, which explicitly takes into account correlation within repeated measures. These analyses provide a clear picture of symptom comparisons between the two treatments. The application of various methods offers not only an approach to assessing the robustness of the results but also a basis for investigating reasons for inconsistency of results across methods. We conclude that except lethargy, which is worse in the ACE+G-CSF arm, all symptoms are similar across the two arms during the treatment period.

Amsacrine↗