Biomedical subjects

W Qian

Publications and source records attributed to W Qian.

At least 91 records · Page 5Linked to original sources

PubMed1998

[Analysis of paracetamol, caffeine and chlorphenamine maleate in suxiaoshangfeng capsules by capillary gas chromatography].

A simple and rapid method for simultaneous determination of paracetamol, caffeine and chlorphenamine maleate in Suxiaoshangfeng capsule by capillary gas chromatography with n-hexadecane as internal standard has been reported. In the capsule, the three components can be separated on a 5% Ph-Me-Silicone column (2.65 microns x 0.53 mm x 10 m), with programmed column temperature from 180 degrees C to 230 degrees C at 8 degrees C/min, hold 6 min and then 230 degrees C to 260 degrees C at 10 degrees C/min, hold 10 min. Both the injector and FID detetor temperatures were 280 degrees C. N2 flow rate was 3.5 mL/min and H2 35 mL/min. The injection volume was 1 uL with splitting ratio of 1/25. These components were identified by their retention times and quantitatively determined by their peak areas. The calibration curves were, r = 0.9996 for paracetamol, r = 0.9984 for caffeine and r = 0.9996 for chlorphenamine maleate. The linear ranges were 4.0-20 g/L, 0.15-0.75 g/L and 0.080-0.40 g/L, respectively. The average recoveries were 99.62% (RSD = 0.40%, n = 5), 96.46%. (RSD = 1.32%, n = 5) and 98.55% (RSD = 0.65%, n = 5), respectively.

Acetaminophen↗

PubMed1998

[Immunologic and clinical study of paraneoplastic limbic encephalitis].

OBJECTIVE: To probe into the pathogenic mechanisms of paraneoplastic limbic encephalitis (PLE) in patients with small cell lung carcinoma (SCLC). METHODS: The indirect immunoperoxidase method and Western blot analysis were used for detecting anti-Hu antibodies in 16 PLE patients associated with SCLC. Autopsy and pathological study were performed on two cases. RESULTS: Eight patients (50%) had anti-Hu antibodies (anti-Hu+) whereas eight patients (50%) no detectable antineuronal antibodies (anti-Hu-). The clinical and laboratory features of PLE and time to diagnosis of SCLC were similar in the anti-Hu+ and anti-Hu- groups. Involvement of other areas of the nervous system in seven (87.5%) patients of the anti-Hu+ group but in only one (12.5)% of the anti-Hu- group (P = 0.012). CONCLUSIONS: The presence of this characteristic neurological disorder strongly suggested that with an accompanying SCLC, existence of anti-Hu autoantibody was in favour of an autoimmune mechanism participating in PLE.

Antibodies, Antinuclear↗

PubMed1998

[Research on inhibition of sodium fluoride on five subgingival bacteria in vitro].

This in vitro study was aimed at observing inhibition action of fluoride on 5 common periodontal bacteria in subgingival microflora. The liquid media two-fold dilution method was used to determine the minimal inhibition concentration (MIC) of sodium fluoride (NaF) to 9 strains of bacteria representing the main periodontopathic species(P. gingivalis, A. actinomycetemcomitans, P. intermedius) and the periodontal beneficial species (S. sanguis) and 1 strain of S. sorbrinus. The results showed that all the bacteria were inhibited at different concentration of NaF. The MIC values ranged from 128 micrograms/ml for P. gingivalis and A. actinomycetemcomitans, 256 micrograms/ml for S. sorbrinus, 1024 micrograms/ml for P. intermedius to 2048-4096 micrograms/ml for S. sanguis. The results suggest that NaF can also be used as a periodontal anti-bacterium agent and those preparations containing about 1000 micrograms/ml fluoride can be used effectively against the periodontopathic bacteria without disturbing the local ecological balance.

Aggregatibacter actinomycetemcomitans↗

PubMed1998

Glutathione conjugation of trichloroethylene in rats and mice: sex-, species-, and tissue-dependent differences.

Glutathione (GSH) conjugation of trichloroethylene (Tri) to form S-(1,2-dichlorovinyl)glutathione (DCVG) has been implicated in the nephrotoxicity and nephrocarcinogenicity of Tri. Marked sex- and species-dependent differences exist, however, in the susceptibility to Tri-induced renal toxicity, with the male rat being the most susceptible. The present study, therefore, focuses on potential differences in the initial step of the GSH pathway. Rates of DCVG formation were measured in suspensions of isolated renal cortical cells and isolated hepatocytes from male and female Fischer 344 rats and in kidney and liver microsomes and cytosol from male and female Fischer 344 rats and B6C3F1 mice to determine if sex- and species-dependent differences in GSH conjugation correlate with susceptibility to renal toxicity from Tri. Rates of gamma-glutamyltransferase (GGT) with gamma-glutamyl-p-nitroanilide and glycylglycine as substrates and GSH S-transferase (GST) with 1-chloro-2,4-dinitrobenzene as substrate were also measured in liver and kidney subcellular fractions to provide further information on the biochemical basis of susceptibility to Tri. Rates of DCVG formation in rat kidney cells and kidney subcellular fractions were 5- to 20-fold lower than those in rat hepatocytes and liver subcellular fractions. Rates of DCVG formation in kidney cells and subcellular fractions were comparable in male and female rats with the exception of male rat kidney microsomes, where DCVG formation was below the limit of detection, and those in liver cells and subcellular fractions were >3-fold higher in male rats than in female rats. Rates of DCVG formation in mouse kidney subcellular fractions were approximately 10-fold higher than in corresponding fractions from the rat, whereas those in mouse liver subcellular fractions were 4- to 8-fold higher than in corresponding rat tissues, with rates in male mouse liver cytosol and microsomes being modestly higher than in corresponding fractions from female mice. GGT activity was barely detectable in livers, was about 20-fold higher in rat kidneys than in mouse kidneys, and was slightly higher in female rat kidneys than in male rat kidneys. GST activity with 1-chloro-2,4-dinitrobenzene as substrate exhibited tissue-, sex-, and species-dependent patterns that were generally similar to those with Tri as the substrate. These results suggest that the higher susceptibility to Tri-induced renal toxicity of male rats as compared with female rats correlates with rates of DCVG formation. The high rates of DCVG formation in mice, however, indicate that other factors, possibly including differences in activities of cysteine conjugate beta-lyase or N-acetyltransferase, may also be important determinants of the susceptibility to Tri.

Animals↗

PubMed1997

Abnormal change of p53 gene in gastric and precancerous lesions and APC gene deletion in gastric carcinoma and near tissues.

p53 gene mutation (exon4, 5, 6, 7, 8 and intron6) in gastric cancer and precancerous lesions and p53 gene (exon4 and ontron6), APC gene deletion in gastric carcinomas were studied by PCR/SSCP and PCR/RFLP. Results showed mutation rate of p53 in metaplasia, dysplasia and gastric carcinoma was 37.5% (3/8), 42.17% (8/19), 53.33 (16/30) respectively. There was significant difference among groups of metaplasia, dysplasia, cancer and normal controls. No exon8 mutation was found in metaplasia and dysplasia, but 4 cases were found to have exon8 mutation in cancer group. It is suggested that exon8 mutation occurs at the late stage of gastric cancer, but exon 5, 6, 7 mutation occur in the course of precancerous lesion to cancer. Loss of heterozygosity (LOH) of exon4, intron6, APC was 47, 37% (9/19), 8.73% (2/23), 16.67% (3/18) respectively. LOH of exon4 had something to do with poor differentiation, lymph node metastasis, depth of invasion. LOH of exon4 may be of prognostic marker of gastric cancer. We are led to conclude that p53 gene mutation is an early event and perhaps work together with ras oncogene in gastric carcinogenesis.

Gastric Mucosa↗

PubMed1997

Digital mammography: computer-assisted diagnosis method for mass detection with multiorientation and multiresolution wavelet transforms.

RATIONALE AND OBJECTIVES: The authors evaluated a modular computer-assisted diagnosis (CAD) method for mass detection that uses computation of features in three domains (gray level, morphology, and directional texture). Their objectives were to improve the sensitivity of detection and reduce the false-positive (FP) detection rate. MATERIALS AND METHODS: The directional wavelet transform (DWT) method, which uses both multiorientation and multiresolution wavelet transforms to improve image preprocessing and segmentation of suspicious areas and to extract both morphologic and directional texture features, was evaluated with a previously reported image database containing 50 normal and 45 abnormal digitized screen-film mammograms. The mammograms contained all mass types and included 16 minimal cancers. This method was compared with the Markov random field (MRF) method to avoid issues related to case selection criteria. Free-response receiver operating characteristic curves were compared for both DWT and MRF methods. RESULTS: For the DWT method, the sensitivity was 98% and the FP detection rate was 1.8 FP findings per image. For the MRF method, the sensitivity was 90% and the FP detection rate was 2.0 FP findings per image. CONCLUSION: The CAD method applied to the full mammographic image is automatic and independent of mass type. The segmentation of masses as performed with this method may potentially allow visual interpretation according to American College of Radiology criteria.

Algorithms↗

PubMed1997

Role of p53 mutation in polyomavirus-induced tumorigenesis.

Small DNA tumour viruses, such as simian virus 40 (SV40), papilloma viruses and adenoviruses, encode proteins that form complexes with and inactivate the p53 and retinoblastoma (RB) proteins. This convergent evolution reflects the common need of these viruses to inactivate these two important regulators of cell cycle progression and cell survival. Polyomavirus, a close relative of SV40, is different. Its large T protein complexes only with RB, not with p53. We have examined whether this is compensated by the frequent appearance of p53 mutations in polyomavirus-induced tumours. We tested the p53 status of 15 polyomavirus-induced sarcomas. Two sarcomas were p53-negative while six carried mutant p53. Another six sarcomas expressed low levels of wild-type p53. One tumour expressed high levels of wild-type p53 protein as shown by DNA sequencing and immunofluorescence staining. MDM2 amplification was not detected in any of the tumours, but Northern blotting showed that MDM2 was overexpressed in at least two tumours that expressed wild-type p53 and in one tumour that expressed both wild-type and mutant p53. Treatment with the DNA-damaging agent mitomycin C caused p53 protein accumulation followed by induction of MDM2 and WAF1/p21 mRNA in four of the tumours expressing wild-type p53, indicating that p53-mediated transcriptional activation was unaltered in these tumours. However, p53-mediated transactivation of WAF1/p21 was impaired in the wild-type p53-expressing tumours that expressed elevated levels of MDM2. These results demonstrate that p53 mutation and inactivation are frequently but not invariably involved in polyomavirus-induced tumorigenesis.

Animals↗

PubMed1997

[The stress reaction induced by intensive noise exposure in rats].

To study the effects of sustained intensive noise on rats, fifty SD male rats were randomly divided into: control group and 1 d, 3 d, 7 d and 14 d noise exposure groups (120 dBSPL, broadband noise, 2 h daily). The results showed that after noise exposure, the ACTH level and the corticosterone level in serum increased, but the content of DA in diencephalon decreased, the weight of adrenal gland increased, while that of thymus and spleen decreased. Change of weight of adrenal gland and thymus became maximum after 7d-exposure. The ACTH level in serum and the content of DA in diencephalon decreased and the later reached the lowest value and the weight of adrenal gland and thymus returned to normal level after 14 d exposure. It indicated that the acute response began to decrease after 7d-exposure, and the response turned into a chronic inhibitory state after 14d-exposure.

Adrenal Glands↗

PubMed1997

[Research on omni-directional ultrasonic imaging].

In this paper, an omni-direction M-mode ultrasonic imaging method is introduced, in which M-mode sample line can rotate and move freely. In this way the measurement of parameters such as amplitude and speed of movement of organs can be conducted in any position or direction. We analyzed the sources of errors of the method and the way to overcome them.

Echocardiography↗

PubMed1996

Design of novel cholecystokinin-B receptor ligands based on the 'double-ring system' approach.

A structurally novel series of cholecystokinin-B (CCK-B) receptor ligands has been designed and synthesized based on the 'double ring system' theory of receptor recognition. Compounds 2b-cis and 2g-cis from this 1-amino-2-benzyltetralin series show modest CCK-B receptor affinity, with IC50 values of 48.5 nM and 39.0 nM, respectively. The results are discussed in the context of ongoing efforts to identify the CCK-B receptor binding site for nonpeptide ligands.

Binding Sites↗

PubMed1996

Expression of vaccinia virus K3L protein in yeast inhibits eukaryotic initiation factor-2 kinase GCN2 and the general amino acid control pathway.

Phosphorylation of the alpha subunit of eukaryotic initiation factor-2 (eIF-2) is a well characterized mechanism regulating protein synthesis. Viral and cellular proteins have been identified that regulate the activity of the eIF-2alpha kinases. The regulatory protein, K3L, from vaccinia virus is homologous to the amino terminus of eIF-2alpha and is thought to inhibit the activity of the double-stranded RNA-dependent kinase suppressing the antiviral mechanism mediated by this kinase. We investigated whether K3L can inhibit the activity of the yeast eIF-2alpha kinase GCN2. Expression of K3L protein in yeast reduced the level of eIF-2alpha phosphorylation by GCN2 and blocked the stimulation of the general amino acid control pathway in response to starvation conditions. Accompanying in vitro studies showed that recombinant K3L protein reduced GCN2 autophosphorylation and phosphorylation eIF-2alpha. In agreement with the hypothesis that K3L inhibits eIF-2alpha kinases by functioning as a pseudosubstrate, we observed that K3L directly interacted with the kinase catalytic domain of GCN2. Together, these results indicate that K3L is a specific inhibitor of eIF-2alpha kinases from mammals and yeast and suggest that the kinases contain common structural features important for recognition of their substrate eIF-2alpha.

Amino Acid Sequence↗

PubMed1996

Interpretation of calcifications in screen/film, digitized, and wavelet-enhanced monitor-displayed mammograms: a receiver operating characteristic study.

RATIONALE AND OBJECTIVES: The acceptance of filmless digital mammography is currently limited by digitization and display drawbacks, as well as bias toward hard-copy interpretation. In the current study, we evaluated a wavelet-based image enhancement method for the filmless interpretation of breast calcifications. METHODS: A set of 100 mammograms (58 with calcification clusters) was digitized at 105 microns and 4,096 gray levels per pixel and was processed with nonlinear filters and wavelets. Standard receiver operating characteristic analysis was performed by four radiologists, who independently read the films, the unprocessed digital images, and unprocessed and wavelet-enhanced digital images presented simultaneously. RESULTS: Statistical differences were observed between screen/film and unprocessed digitized mammography displayed on monitors. Differences were not significant when wavelet enhancement was included in the monitor display. Interobserver variation in the digitized reading was greater than in film reading, but the wavelet enhancement reduced the difference. CONCLUSION: Wavelet-enhanced digital mammograms may assist radiologists in diagnosing calcifications directly from computer monitors and may compensate for current technologic limitations. A study with a larger data-base is needed before this method is accepted for clinical use.

Breast Diseases↗

PubMed1996

A restoration algorithm for P-32 and Y-90 bremsstrahlung emission nuclear imaging: a wavelet-neural network approach.

A novel wavelet-based neural network (WNN) filter is proposed for image restoration as required for imaging of beta emitters by bremsstrahlung detection using a gamma camera. Quantitative imaging of beta emitters is important for the in vivo management of antibody therapy using either P-32 or Y-90. The theoretical basis for the general case for M-channel multiresolution wavelet decomposition of the nuclear image into different subimages is developed with the objective of isolating the signal from noise. A modified Hopfield neural network (NN) architecture is then used for multichannel image restoration using the dominant signal subimages. The NN model avoids the common inverse problem associated with other image restoration filters such as the Wiener filter. The relative performance of the WNN for image restoration, for M = 2 channel, is compared to a previously reported order statistic neural network hybrid (OSNNH) filter. Initially simulated degraded images of known structures with different noise levels are used. Quantitative metrics such as the normalized mean square error (NMSE) and signal-to-noise ratio (SNR) are used to compare filter performance. The WNN yields comparable results for image restoration with suggested slightly better performance for the images with higher noise levels as often encountered in bremsstrahlung detection. Attenuation measurements were performed using two radionuclides, 32P and 90Y as required for calibration of the gamma camera for quantitative measurements. Similar values for an effective attenuation coefficient were observed for the restored images using the OSNNH filters (32P: mu = 0.122 cm-1, 90Y: mu = 0.135 cm-1) and WNN (32P: mu = 0.122 cm-1, 90Y: mu = 0.135 cm-1) filters with slightly higher values obtained for the raw data (32P: mu = 0.142 cm-1, 90Y: mu = 0.142 cm-1) for a 3.5-cm source size. The WNN, however, was computationally more efficient by a factor of 4 to 6 compared to the OSNNH filter. The filter architecture, in turn, is also optimum for parallel processing or VLSI implementation as required for planar and particularly for SPECT mode of detection.

Algorithms↗

PubMed1996

Human cataract risk factors: significance of abstention from, and high consumption of, ethanol (U-curve) and non-significance of smoking.

Current ethanol consumption and cigarette smoking were quantified by questionnaire in Edinburgh and suburbs, Scotland, UK. Stringently matched cataract-control pairs (n = 990 and 858, respectively) were included. For ethanol, 'light and infrequent' consumption and 'light and frequent' were associated with a significantly lower risk of cataract than were total abstention and 'occasional' consumption; the prevalence of cataract rose with further increases in consumption, suggesting a U-shaped curve. For nuclear cataract, white in particular, there is a significant trend with amount consumed. Smoking was not found to be a risk factor.

Alcohol Drinking↗

PubMed1995

Progression to androgen insensitivity in a novel in vitro mouse model for prostate cancer.

We have shown previously that the ras and myc oncogenes can induce poorly differentiated mouse prostate carcinomas in vivo with high frequency (greater than 90%) using inbred C57BL/6 mice in the mouse prostate reconstitution model system. To study the androgen sensitivity of these carcinomas, we have developed an in vitro model system which includes a cell line from normal urogenital sinus epithelium (CUGE) and cell lines from three ras + myc transformed mouse prostate carcinomas (RM-9, RM-1, and RM-2). CUGE cells, as well as all prostate carcinoma cell lines, were positive for cytokeratin 18 mRNA and immunoreactive to cytokeratin-specific antiserum. Two out of three of the early passage carcinoma cell lines were clonal with respect to Zipras/myc 9 retrovirus integration as determined by Southern blot analysis. Whereas significant mitogenic effects of testosterone (10 nM) were not seen in CUGE cells grown in serum-free medium, under similar conditions approx. 2-fold increases in cell number were seen in all low passage prostate carcinoma cell lines. Also, in the presence of growth inhibitory levels of suramin (50 micrograms/ml), testosterone was capable of significant growth stimulation in the carcinoma cell lines. With further propagation from low passage [20-25 population doublings (PD)] to high passage (75-100 PD), all carcinoma cell lines demonstrated increased and similar growth rate in the presence and absence of testosterone. These cell lines maintained stable androgen receptor numbers and binding kinetics during the transition from testosterone-responsive growth to reduced responsivity over multiple passages in culture (> 150 PD). Overall, our studies indicate that the capacity to bind testosterone is stably maintained through the transition of the androgen-sensitive to insensitive phenotype and raise the possibility that androgen sensitivity can persist throughout progression but is masked by the acquisition of autocrine pathways.

Androgens↗

PubMed1995

Infrequent MDM2 gene amplification and absence of gross WAF1 gene alterations in nasopharyngeal carcinoma.

We have investigated the possible involvement of MDM2 and WAF1 gene alterations in the development of nasopharyngeal carcinoma (NPC). MDM2 and WAF1 were analysed in 46 primary NPCs by Southern blot analysis. Forty-five tumours showed a normal EcoRI hybridisation pattern and hybridisation intensity with a human MDM2 cDNA probe. One tumour had more intense normal size MDM2 hybridising bands. Densitometric scanning revealed a 10-12-fold MDM2 gene amplification, as compared with human placenta DNA. All 46 tumours showed normal size WAF1 EcoRI bands that hybridised with normal intensity. This is the first demonstration of MDM2 gene amplification in NPC. Nonetheless, our analysis indicates that gross structural alterations of the MDM2 and WAF1 genes are infrequent events in the genesis of NPC.

Blotting, Southern↗

PubMed1995

Tree structured wavelet transform segmentation of microcalcifications in digital mammography.

A novel multistage algorithm is proposed for the automatic segmentation of microcalcification clusters (MCCs) in digital mammography. First, a previously reported tree structured nonlinear filter is proposed for suppressing image noise, while preserving image details, to potentially reduce the false positive (FP) detection rate for MCCs. Second, a tree structured wavelet transform (TSWT) is applied to the images for microcalcification segmentation. The TSWT employs quadrature mirror filters as basic subunits for both multiresolution decomposition and reconstruction processes, where selective reconstruction of subimages is used to segment MCCs. Third, automatic linear scaling is then used to display the image of the segmented MCCs on a computer monitor for interpretation. The proposed algorithms were applied to an image database of 100 single view mammograms at a resolution of 105 microns and 12 bits deep (4096 gray levels). The database contained 50 cases of biopsy proven malignant MCCs, 8 benign cases, and 42 normal cases. The measured sensitivity (true positive detection rate) was 94% with a low FP detection rate of 1.6 MCCs/image. The image details of the segmented MCCs were reasonably well preserved, for microcalcification of less than 500 microns, with good delineation of the extent of the microcalcification clusters for each case based on visual criteria.

Calcinosis↗

PubMed1995

[Quantitative study of myocardial mitochondrial DNA4977 deletion in rheumatic heart disease and its significance].

To better understand the mechaenisms of cardiac function damaged by chronic hypoxemia in rheumatic heart disease, we investigated the level of the 4977 base pair mitochondrial DNA (mtDNA4977) deletion in 16 patients with rheumatic heart disease (RHD) by using polymerase chain reaction (PCR). Myocardial malondialdehyde (SOD) activity was also measured. In control group, mtDNA4977 deletion appeared after 45 years old and reached a maximum of 0.0042%. A higher level of mtDNA4977 deletion (0.02%-1.26%) was found in RHD group. Because mtDNA4977 deletion removes 8 genes coding for subunits of complexes of respiratory chain, its deletion can inhibit oxidative phosphorylation, reduce ATP production and hinder the recovery of cardiac function. In addition, myocardial MDA content increased and SOD activity decreased in the RHD group as compared with the control group. This indicates that the generation of oxygen free radicals enhances and the elimination of free radicals reduces. Oxygen free radical can be an important factor in myocardial mitochondrial DNA injury and lead to mitochondrial DNA deletion.

Adult↗