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Yan Zhang

Publications and source records attributed to Yan Zhang.

At least 271 records · Page 15Linked to original sources
PubMed2005

On the Euclidean distance of images.

We present a new Euclidean distance for images, which we call IMage Euclidean Distance (IMED). Unlike the traditional Euclidean distance, IMED takes into account the spatial relationships of pixels. Therefore, it is robust to small perturbation of images. We argue that IMED is the only intuitively reasonable Euclidean distance for images. IMED is then applied to image recognition. The key advantage of this distance measure is that it can be embedded in most image classification techniques such as SVM, LDA, and PCA. The embedding is rather efficient by involving a transformation referred to as Standardizing Transform (ST). We show that ST is a transform domain smoothing. Using the Face Recognition Technology (FERET) database and two state-of-the-art face identification algorithms, we demonstrate a consistent performance improvement of the algorithms embedded with the new metric over their original versions.

Algorithms↗
PubMed2005

Crystal structures of apo wild-type M. jannaschii tyrosyl-tRNA synthetase (TyrRS) and an engineered TyrRS specific for O-methyl-L-tyrosine.

The Methanococcus jannaschii tRNA(Tyr)/TyrRS pair has been engineered to incorporate unnatural amino acids into proteins in E. coli. To reveal the structural basis for the altered specificity of mutant TyrRS for O-methyl-L-tyrosine (OMeTyr), the crystal structures for the apo wild-type and mutant M. jannaschii TyrRS were determined at 2.66 and 3.0 A, respectively, for comparison with the published structure of TyrRS complexed with tRNA(Tyr) and substrate tyrosine. A large conformational change was found for the anticodon recognition loop 257-263 of wild-type TyrRS upon tRNA binding in order to facilitate recognition of G34 of the anticodon loop through pi-stacking and hydrogen bonding interactions. Loop 133-143, which is close to the tRNA acceptor stem-binding site, also appears to be stabilized by interaction with the tRNA(Tyr). Binding of the substrate tyrosine results in subtle and cooperative movements of the side chains within the tyrosine-binding pocket. In the OMeTyr-specific mutant synthetase structure, the signature motif KMSKS loop and acceptor stem-binding loop 133-143 were surprisingly ordered in the absence of bound ATP and tRNA. The active-site mutations result in altered hydrogen bonding and steric interactions which favor binding of OMeTyr over L-tyrosine. The structure of the mutant and wild-type TyrRS now provide a basis for generating new active-site libraries to evolve synthetases specific for other unnatural amino acids.

Crystallography, X-Ray↗
PubMed2005

Double-blind, crossover comparison of olopatadine and cetirizine versus placebo: suppressive effects on skin response to histamine iontophoresis.

Olopathadine, a newly developed histamine H1-receptor antagonist, was compared with cetirizine in its suppressive effects on histamine-induced wheal and flare reaction using an iontophoresis technique in a double-blind, crossover, placebo-controlled fashion. As a result, olopathadine was found to have effects comparable to cetirizine. This finding may predict the efficacy of this new H1-antagonist in treating pruritic skin diseases.

Administration, Oral↗
PubMed2005

MHC class I chain-related gene A-A5.1 allele is associated with ulcerative colitis in Chinese population.

The human MHC class I chain-related gene A (MICA) plays a role in regulating protective responses by intestinal epithelial Vdelta1 gamma delta T cells and the polymorphism of MICA were reported to be related to several autoimmune diseases. The present study aimed to investigate the association of the microsatellite polymorphisms of TM region of MICA gene with the susceptibility to ulcerative colitis (UC) in Chinese population. The microsatellite polymorphisms of the MICA were genotyped in unrelated 86 Chinese patients with UC and 172 ethnically matched healthy controls by a semiautomatic fluorenscently labelled PCR method. All the subjects were the Chinese with Han nationality. The frequency of MICA-A5.1 homozygous genotype and A5.1 allele were significantly increased in UC patients compared with healthy controls (22.1%versus 7%, P = 0.0009, Pc = 0.0126, OR = 3.781, 95%CI: 1.738-8.225 and 30.2%versus 17.4%, P = 0.0014, Pc = 0.007, OR = 2.051, 95%CI: 1.336-3.148, respectively). Adjusted the effects of gender and age at onset, MICA-A5.1 homozygous genotype and A5.1 allele were also increased in the UC patients. Moreover MICA-A5.1 allele was significantly increased in frequency in the female UC patients (38.2%versus 21.0%, P = 0.0095, Pc = 0.0475, OR = 2.326, 95%CI: 1.234-4.382). Logistic regression analysis also revealed that gender was independently associated with UC patients carried MICA-A5.1 allele (P = 0.046, OR (male) = 0.511, 95% CI: 0.264-0.987). Although the UC patients with extensive colitis (32.5%versus 17.4% in the healthy controls, P = 0.005, Pc = 0.025) and the UC patients with extraintestinal manifestations (36%versus 17.4% in the healthy controls, P = 0.0039, Pc = 0.0195) were more likely to carry the MICA-A5.1 allele, EIMs was associated with extent of disease (P < 0.0001, OR (with EIMs) = 3.511, 95% CI 1.747-7.056) and MICA-A5.1 allele was not associated with UC patients with extensive colitis or with EIMs in the logistic regression analysis. Therefore, the MICA-A5.1 homozygous genotype and A5.1 allele were closely associated with UC and the MICA-A5.1 allele was positively associated with the female UC patients in Chinese population.

Adolescent↗
PubMed2005

Leaf nitrogen and phosphorus stoichiometry across 753 terrestrial plant species in China.

Leaf nitrogen and phosphorus stoichiometry of Chinese terrestrial plants was studied based on a national data set including 753 species across the country. Geometric means were calculated for functional groups based on life form, phylogeny and photosynthetic pathway, as well as for all 753 species. The relationships between leaf N and P stoichiometric traits and latitude (and temperature) were analysed. The geometric means of leaf N, P, and N : P ratio for the 753 species were 18.6 and 1.21 mg g(-1) and 14.4, respectively. With increasing latitude (decreasing mean annual temperature, MAT), leaf N and P increased, but the N : P ratio did not show significant changes. Although patterns of leaf N, P and N : P ratios across the functional groups were generally consistent with those reported previously, the overall N : P ratio of China's flora was considerably higher than the global averages, probably caused by a greater shortage of soil P in China than elsewhere. The relationships between leaf N, P and N : P ratio and latitude (and MAT) also suggested the existence of broad biogeographical patterns of these leaf traits in Chinese flora.

China↗
PubMed2005

Vascular endothelial growth factor 121 is the predominant isoform in psoriatic scales.

Vascular endothelial growth factor (VEGF) is a powerful agent that causes hyperpermeability of blood vessels as well as endothelial cell proliferation. Recent investigations have revealed that production of VEGF increases in epidermis of psoriatic lesions, and the overproduced VEGF plays an important role in the pathogenesis of psoriasis. In this study, we used immunohistochemical staining as well as extraction of stratum corneum with physiological saline to further analyse VEGF produced in psoriatic lesions. Biological activity of VEGF in the psoriatic scales was assayed by cultured human umbilical vein endothelial cells in vitro. The immunohistochemical examination confirmed an increased production of VEGF in the keratinocytes of psoriatic lesions. In addition, we found that the content of VEGF contained in the psoriatic scales was approximately 50 times greater than that in normal stratum corneum. We also found that VEGF 121 isoform, which has an exclusive ability to cause hyperpermeability of blood vessels, was predominantly detected in psoriatic scales, suggesting a major role of VEGF 121 isoform on the altered structure of microvessels in psoriatic lesions.

Cells, Cultured↗
PubMed2005

Development of an HSV-tk transgenic mouse model for study of liver damage.

The herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system that selectively depletes cells expressing HSV-tk upon treatment with GCV has provided a valuable tool for developing a new animal model expressing the desired tissue damage. In this paper, an HSV-tk vector with an albumin promoter/enhancer was constructed. Based on the favourable killing effect on Hep-G2 cells by the recombinant construct, the HSV-tk transgenic mouse strains were developed. One strain of the TK transgenic mouse (TK5) was studied intensively. Integration of the target gene was confirmed primarily by PCR. Fluorescence in situ hybridization following G-banding analysis demonstrated that the insertion site was located at 2F1-G3. The hepatocyte-specific transcription and expression of HSV-tkwas verified by reverse transcription (RT)-PCR as well as by immunohistochemical staining. When two second-generation mice (TK5-F1 and TK5-F2) were injected with GCV, the pathogenic alterations in the liver were readily identified, including the appearance of vaculation in the hepatocytes with inflammatory infiltration in the liver, and diffuse proliferation of hepatocytes. In addition, the blood test demonstrates a significant increase of serum alanine aminotransferase, aspartate aminotransferase and total bilirubin. In conclusion, the transgenic mouse model with hepatocyte-specific expressed HSV-tk developed hepatitis with administration of GCV, had morphological and clinical chemical characteristics indicative of hepatocellular disease and should be useful for the the study of inducible liver-specific diseases.

Animals↗
PubMed2005

Urinary metabolites of a tobacco-specific lung carcinogen in nonsmoking hospitality workers.

Exposure of nonsmokers to environmental tobacco smoke results in increased risk for cancer and other diseases. In spite of this finding, some restaurants and bars continue to permit smoking. This study examined the uptake of nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent lung carcinogen, in nonsmokers who work in restaurants and bars that permitted smoking. Urine samples were collected for 24 hours on working and nonworking days and were analysed for total NNAL [the sum of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides (NNAL-Glucs)], metabolites of NNK. In addition, urine samples were analysed for total nicotine (nicotine plus nicotine glucuronide), and total cotinine (cotinine plus cotinine-N-glucuronide). The results showed significant increases in urinary levels of total NNAL, total nicotine, and total cotinine on working days compared with nonworking days. The results of this study show that smoke exposure in bars and restaurants may have important health effects on nonsmoking employees, elicited by the increase in carcinogen levels.

Adolescent↗
PubMed2005

Relationships between cigarette consumption and biomarkers of tobacco toxin exposure.

Epidemiologic studies show a dose-response relationship between cigarettes per day and health outcomes such as heart and lung disease, and health outcomes are related to some biomarkers of tobacco exposure. The objective of this study was to examine the relationships between cigarettes per day and levels of selected biomarkers of tobacco toxin exposure: carbon monoxide (CO), metabolites of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and polycyclic aromatic hydrocarbons [total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and 1-hydroxypyrene (1-HOP), respectively], and total cotinine (cotinine plus cotinine-N-glucuronide). We did a cross-sectional analysis of merged data from (a) two clinical trials and (b) two cohorts of light smokers (total n = 400). The mean age of participants was 50.4 years and the range of cigarette consumption was 1 to 100/d; however, few subjects smoked >45 cigarettes/d (n = 12). Results show that levels of the biomarkers CO, total NNAL, and total cotinine increase with an increase in the number of cigarettes smoked per day, but not in a linear fashion. 1-HOP is a less discriminating biomarker as levels are relatively stable regardless of the number of cigarettes smoked per day. There is considerable variability in toxin measurement, especially at high levels of smoking. There was a significant correlation between cigarettes per day and total NNAL, 1-HOP, total cotinine, and CO. Total NNAL was highly significantly correlated with total cotinine and CO and also significantly correlated with 1-HOP. These findings suggest that the number of cigarettes smoked per day is not necessarily a reliable measure of toxin exposure and may underestimate tobacco toxin exposure at low levels of smoking or overestimate exposure at high levels of smoking.

Biomarkers↗
PubMed2005

Increase in bone mass and bone strength by Sambucus williamsii HANCE in ovariectomized rats.

Herbal Sambucus williamsii HANCE (SWH) is a folk medicine with a long history of safe use for treatment of bone fractures and joint diseases in China. The present study was designed to investigate if SWH extract could be used for treatment of postmenopausal osteoporosis. SWH extracts (30 or 60 mg/100 g body weight/d) were orally administrated to four-months-old ovariectomized (OVX) rats for 3 months. SWH extracts did not alter weight gain and uterus weight in OVX rats. SWH extracts significantly increased serum Ca levels (p<0.05, vs. OVX control group) as well as decreased urinary Ca excretion (p<0.01, vs. OVX control group) in OVX rats. The upregulation of serum alkaline phosphatase, serum osteocalcin as well as urinary deoxypyridinoline levels by OVX was suppressed by treatment with SWH extracts in rats (p<0.05, vs. OVX control group). SWH extract increased the stiffness of femur at both dosage (p<0.05, vs. OVX control group) and increased tibial bone mineral density at 60 mg/100 g body weight/d (p<0.05, vs. OVX control group) in OVX rats. Our results indicate that orally administrated SWH extracts can decrease urinary calcium excretion and bone turnover rate in OVX rats, resulting in positive effects on biomechanical strength of bone and bone mineral density. This study is the first to report that SWH could be considered as a potential candidate for management of postmenopausal osteoporosis. Then in vitro experiments were performed to determine the potential molecular mechanism of the anti-osteoporotic effect of SWH. Results suggested that chloroform fraction and ethyl acetate fraction of SWH can inhibit osteoclastogenesis osteoclast by modulating the expression of osteoprotegrin (OPG) and receptor activator of NF-kappaB ligand (RANKL) mRNA in osteoblastic UMR 106 cells. Both of them increased OPG mRNA and decreased RANKL mRNA expression, resulting in a dose-dependent increase in OPG/RANKL mRNA ratio (p<0.01, vs. vehicle-treated). Taken together, SWH treatment can effectively suppress the OVX-induced increase in bone turnover and its effects might be mediated by a decrease in osteoclastogenesis.

Animals↗
PubMed2005

Sensitive detection of SARS coronavirus RNA by a novel asymmetric multiplex nested RT-PCR amplification coupled with oligonucleotide microarray hybridization.

We have developed a sensitive method for the detection of specific genes simultaneously. First, DNA was amplified by a novel asymmetric multiplex PCR with universal primer(s). Second, the 6-carboxytetramethylrhodamine (TAMRA)-labeled PCR products were hybridized specifically with oligonucleotide microarrays. Finally, matched duplexes were detected by using a laser-induced fluorescence scanner. The usefulness of this method was illustrated by analyzing severe acute respiratory syndrome (SARS) coronavirus RNA. The detection limit was 10(0) copies/microL. The results of the asymmetric multiplex nested reverse transcription-PCR were in agreement with the results of the microarray hybridization; no hybridization signal was lost as happened with applicons from symmetric amplifications. This reliable method can be used to the identification of other microorganisms, screening of genetic diseases, and other applications.

Oligonucleotide Array Sequence Analysis↗
PubMed2005

[Effects of liuwei dihuang pills on expressions of apoptosis-related genes bcl-2 and Bax in pancreas of OLETF rats].

OBJECTIVE: To investigate the effects of Liuwei Dihuang Pills (LWDHP) on expressions of apoptosis-related genes bcl-2 and Bax in pancreas of OLETF rats. METHODS: Forty male OLETF rats were randomly divided into LWDHP-treated group and untreated group. Another ten male LETO rats were included in normal control group. OLETF rats in the LWDHP-treated group were given LWDHP (2.4 g.kg(-1).d(-1)) orally since the age of 8 weeks and the rats in the other two groups were given distilled water orally. Body weights of rats were recorded weekly and blood glucose concentration was determined by oral glucose tolerance test (OGTT). Pancreas weights were recorded after rats were killed and the expression levels of bcl-2 mRNA and Bax mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: In the LWDHP-treated group, the expression of bcl-2 mRNA in the pancreas of rats at the age of 40 weeks (1.25+/-0.07) was much higher than that in the untreated group (1.01+/-0.16), P<0.01. Bax mRNA level in the LWDHP-treated group (0.57+/-0.11) was obviously lower than that in the untreated group (1.18+/-0.28), P<0.01. There was no significant difference of pancreas-to-body weight ratios between the LWDHP-treated group and the untreated group. The ability of glucose tolerance was improved in the LWDHP-treated group. CONCLUSION: LWDHP can up-regulate the expression of bcl-2 and down-regulate the expression of Bax at transcription level, which maybe contribute to the anti-apoptosis effects of LWDHP.

Animals↗
PubMed2005

[RT-PCR detecting NUP98-HOX fusion gene in leukemia].

To investigate whether there are NUP98-HOXA, NUP98-HOXB, NUP98-HOXC, NUP98-HOXD fusion genes in leukemia patients in Xinjiang, cellular total RNA was extracted from the bone marrow mononuclear cells, the formaldehyde-agarose gel electrophoresis was used to judge whether RNA was intact, the 17 RT-PCR primers were designed to amplify the predicted fusion junctions and 412 bp GAPDH was used as an internal control, NUP98-HOXA fusion genes were amplified by nested-PCR following reverse transcription. One-step PCR was performed to amplify the other predicted fusion genes. The results showed that RNA was proved to be intact and expression of GAPDH was found in every sample. However, no predicted fusion transcripts were detected in leukemia patients. In conclusion, no NUP98-HOX fusion genes were detected in the samples from Xinjiang.

Adult↗
PubMed2005

[Quantitative morphometry of hyperplastic hypoechoic nodules in the prostatic outer gland].

OBJECTIVE: To explore the morphotic characteristics of hypoechoic nodules in the outer gland of the prostate with benign METHODS: Twenty-two hyperplastic hypoechoic nodules in the prostatic outer gland were biopsied guided by prostatic hyperplasia. transrectal ultrasound. The hematoxylin-eosin (HE) staining and immunohistochemistry combined with computer assisted quantitative image analyses were adopted to examine the mean percentages of the area densities of stroma, epithelium, glandular lumen and smooth muscle cells. RESULTS: The area densities of stroma, epithelium, glandular lumen and smooth muscle cells were (72.52 +/- 13.14)%, (20.57 +/- 9.01)%, (6.85 +/- 4.51)% and (24.14 +/- 6.31)%, respectively. CONCLUSION: Hyperplastic hypoechoic nodules may develop in the outer gland as well as in the inner gland of the prostate, but the mean percentages of the components are different between the two kinds of nodules.

Adult↗
PubMed2005

[Risk factors of sudden death and death from arrhythmia in patients with non-ST elevation acute coronary syndromes in China].

OBJECTIVE: To analyze the relationship between sudden death and death from arrhythmia and multiple risk factors in patients with non-ST elevation acute coronary syndromes in two years of follow-up in China. METHODS: This study was a part of an international multicentre registry-Organization to Assess Strategies for Ischemic Syndromes (OASIS). The patients admitted to the hospital with non-ST elevation acute coronary syndrome were enrolled. No particular intervention was given for the treatment. All patients had been followed-up for two years. The patients' clinical characteristics, therapeutic regimes and major events during hospitalization and two years' follow-up period were recorded by filling in Case Report Forms according to the protocol offered by Canadian Cardiovascular Collaboration. Cox regression model was used to analyze the association with the most common causes of death and multiple factors recorded. RESULTS: From April 1999 to December 2001, 2294 cases were enrolled in 38 hospitals in China nationwide. Among them 2188 patients two years follow-up was accomplished. The mean age of the patients was (62.8+/-8.1) years. Male gender was dominant (62.3%). The clinical diagnosis at admission was unstable angina in 88.5% of the patients and non Q-wave myocardial infarction(MI) in the remaining 11.5%. The mortality was 7.6% with total deaths of 174 by the end of 24-month follow up. The most common cause of death was severe arrhythmias or sudden death (92 cases, 52.9%). More than 70 factors were analyzed by Cox regression model in order to determine which were the predominant factors of death. Major risk factors that predisposed to death were: number of episodes of MI during follow-up period, re-MI within 24 hours during hospitalization, heart failure during hospitalization, previous history of MI, recurrent angina pectoris during hospitalization, the duration of hospitalization, and patient age. Protective factors that reduced the chance of death were: the frequency of using nitrate, frequency of taking anti-platelet medicine or beta-blocker during follow-up period. CONCLUSION: In China, the most common cause of death in patients with non-ST elevation acute coronary syndromes is severe arrhythmias or sudden death, and it is related with the severity of coronary artery disease and the age of patients in majority of cases. Some factors that influence survival are similar to those established by previous evidence based medicine.

Acute Coronary Syndrome↗
PubMed2005

[Effects of low shear stress on expression of platelet derived growth factor (PDGF) of organ-cultured artery in vitro].

To explore the biological effects of shear stress on intact artery and the change of growth factor during stress-induced vascular remodeling, we established an artery organ-cultured system under stress in vitro, and the common carotid arteries of pigs were cultured under shear stress of 20, 5 and 0 dyn/cm2. PDGF-A synthesis of vascular smooth muscle cells (VSMCs) cultured for 1, 4 and 7 days were studied by immunohistochemical and computer image processing methods, and PDGF-B secretion of endothelial cells (ECs) cultured within 12 h were studied by ELISA. Results showed that PDGF-B increased obviously under shear stress of 5 dyn/cm2, and reached the highest point at about 3 h; PDGF-A synthesis also obviously increased under low shear stress in 7 days. Increasing of PDGF synthesis promotes phenotype switch and proliferation of VSMC. It may have important influence on artery remodeling under low shear stress.

Animals↗
PubMed2005

[Pressure-induced expression of immediate-early gene product c-Jun of the common carotid arteries in rats].

In order to investigate the mechanism of mechanical stress-mediated arterial remodeling, we studied the pressure-induced expression of immediate-early response gene product c-Jun in common carotid arteries in rats. The common carotid arteries were perfused with both high pressure (160 mmHg) and normal pressure (80 mmHg) for 0.5, 1, 3 and 6 hours. Expression of immediate-early response gene product c-Jun in the arteries was examined by immunohistochemistry and computer image processing. c-Jun was weakly expressed at 1 h, then increased at 3 h and 6 h after exposure of the arteries to normal pressure. Positive immunohistochemical product of c-Jun appeared in the arteries at 0.5 h after the onset of high pressure, then it increased markedly till 6 h. There was significant difference between the two groups. These results indicate that expression of c-Jun of the arteries can be induced by pressure, which may play an important role in mechanical stress-mediated arterial remodeling.

Animals↗