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Yong Yang

Publications and source records attributed to Yong Yang.

At least 109 records · Page 6Linked to original sources
PubMed2004

Nitric oxide spatial distribution in single cultured hippocampus neurons: investigation by projection of reconstructed 3-D image and visualization technique.

Recent studies have revealed a non-homogeneous distribution of nitric oxide synthase (NOS) in neurons. However, it is not yet clear whether the intracellular distribution of NOS represents the intracellular nitric oxide (NO) distribution. In the present study, software developed in our laboratory was applied to the reconstructed image obtained from confocal slice images in order to project the 3-D reconstructed images in any direction and to cut the neuron in different sections. This enabled the spatial distribution of NO to be visualized in any direction and section. In single neurons, NO distribution was seen to be heterogeneous. After stimulation with glutamate, the spatial changes in different areas of the neuron were different. These findings are consistent with immunocytochemical data on the intracellular localization of nNOS in hippocampus neurons, and will help to elucidate the specificity of nitric oxide signaling. Finally, the administration of SNAP and L-NAME was used to examine DAF-2 distribution in the neurons. The results showed this distribution to be homogenous; therefore, it did not account for the NO distribution results.

Animals↗
PubMed2004

Effect of replacement of fish meal by meat and bone meal and poultry by-product meal in diets on the growth and immune response of Macrobrachium nipponense.

The potential use of poultry by-product meal (PBM) and meat and bone meal (MBM) as alternative dietary protein sources for juvenile Macrobrachium nipponense was studied by a 70-day growth trial. Triplicate groups of M. nipponense (initial body weight: 0.37 g) were fed at 20.7-22.4 degrees C on each of the five isoenergetic and isonitrogenous diets (protein content about 38%) with different replacement of fish meal by MBM or PBM. The control diet used white fish meal as the sole protein source, the other four diets were prepared with 15% or 50% fish meal protein substituted by either MBM (MBM(15), MBM(50)) or PBM (PBM(15), PBM(50)). The results showed that replacement of fish meal by MBM in diets did not affect growth performance of M. nipponense (P > 0.05), while specific growth rate in PBM(15) was significantly higher than that in other groups (P < 0.05). Survival rates of shrimp fed with MBM(15) diet were significantly higher than that in other groups (P < 0.05). No significant differences in immunological parameters, including total haemocyte count (THC), phenoloxidase activity (PO) and respiratory burst (O(2)(-)), were observed between the shrimps that were fed five experimental diets, and all determined immunological parameters in control groups were slightly higher than those in replacement groups. In conclusion, either MBM or PBM investigated could replace up to 50% fish meal protein in diets for M. nipponense.

Analysis of Variance↗
PubMed2004

Phylogenetic relationships of Drosophila melanogaster species group deduced from spacer regions of histone gene H2A-H2B.

Nucleotide sequences of the spacer region of the histone gene H2A-H2B from 36 species of Drosophila melanogaster species group were determined. The phylogenetic trees were reconstructed with maximum parsimony, maximum likelihood, and Bayesian methods by using Drosophila pseudoobscura as the out group. Our results show that the melanogaster species group clustered in three main lineages: (1). montium subgroup; (2). ananassae subgroup; and (3). the seven oriental subgroups, among which the montium subgroup diverged first. In the third main lineage, suzukii and takahashii subgroups formed a clade, while eugracilis, melanogaster, elegans, ficusphila, and rhopaloa subgroups formed another clade. The bootstrap values at subgroup levels are high. The phylogenetic relationships of these species subgroups derived from our data are very different from those based on some other DNA data and morphology data.

Animals↗
PubMed2004

Identification of a novel mutation and a de novo mutation in DKC1 in two Chinese pedigrees with Dyskeratosis congenita.

Dyskeratosis congenita (DKC) is a rare and fatal congenital syndrome characterized by the triad of reticular skin pigmentation, nail dystrophy and mucosal leukoplakia, and the predisposition to bone marrow failure and malignancies. Mutations in DKC1 gene encoding dyskerin are responsible for the X-linked dyskeratosis congenita. Here we report mutation analysis of two Chinese pedigrees with dyskeratosis congenita. The 15 coding exons of DKC1 and their flanking regions were amplified from genomic DNA by PCR. DNA sequencing and restriction endonuclease digestion were used for mutation detection. Transition mutation of 1226C-->T (P409L) found in the first pedigree is a novel mutation. In the second pedigree, the proband's mother phenotypically normal carried a de novo transition mutation of 1058C-->T (A353 V) in one allele, and transmitted the mutant allele to her two sons who had typical manifestations of dyskeratosis congenita.

Adult↗
PubMed2004

Inverse treatment planning with adaptively evolving voxel-dependent penalty scheme.

In current inverse planning algorithms it is common to treat all voxels within a target or sensitive structure equally and use structure specific prescriptions and weighting factors as system parameters. In reality, the voxels within a structure are not identical in complying with their dosimetric goals and there exists strong intrastructural competition. Inverse planning objective function should not only balance the competing objectives of different structures but also that of the individual voxels in various structures. In this work we propose to model the intrastructural tradeoff through the modulation of voxel-dependent importance factors and deal with the challenging problem of how to obtain a sensible set of importance factors with a manageable amount of computing. Instead of letting the values of voxel-dependent importance to vary freely during the search process, an adaptive algorithm, in which the importance factors were tied to the local radiation doses through a heuristically constructed relation, was developed. It is shown that the approach is quite general and the EUD-based optimization is a special case of the proposed framework. The new planning tool was applied to study a hypothetical phantom case and a prostate case. Comparison of the results with that obtained using conventional inverse planning technique with structure specific importance factors indicated that the dose distributions from the conventional inverse planning are at best suboptimal and can be significantly improved with the help of the proposed nonuniform penalty scheme.

Algorithms↗
PubMed2004

[Investigation of the influence of nitric oxide on the survival of a random pattern skin flap].

OBJECTIVE: To investigate the changes of nitric oxide concentration in the distal portion of a random pattern skin flap and the influence of the exogenous L-arginine on the survival of the random pattern skin flap. METHODS: A random pattern skin flap (7 cm x 2 cm) was cranially designed and elevated on the back of a Wistar rat. An image analysis technology was used to evaluate the survival rate of the skin flap, while a biochemistry method was used to test the concentrations of the NO in the tissue. RESULTS: The survival area of the flap in the L-arginine-treated group was significantly enlarged (63.83 +/- 5.13)% (P < 0.01) in seven days postoperatively, compared with the control group (43.26 +/- 2.86)%. The NO concentration in the tissue was no statistic difference between all of the groups immediately after the operation (P > 0.05). But, the NO concentration in the control was decreasing at the beginning and then increasing slightly to reach the high level in 12 hours after the operation. It was thereafter slumped down to the baseline in 72 hours after the surgery. Although the changes in the L-arginine-treated group were quite similar to the control excepting of the extent, the NO concentration was kept in a higher level in the sequential time after the operation (P < 0.01, P < 0.01, P < 0.05 and P < 0.01). CONCLUSIONS: The NO concentration in skin flap tissue after the elevation was going up slightly for a short time. The exogenous L-arginine could promote the NO concentration in the random pattern skin flap to protect it from ischemic injury.

Animals↗
PubMed2004

[Purification of colorectal cancer-associated antigen by immuno-affinity chromatography].

AIM: To purify and characterize the colorectal cancer-associated antigen from cultured colorectal cancer cells. METHODS: The colorectal cancer cell lines that highly expressed the associated antigen were selected by flow cytometry with five specific monoclonal antibodies (mAbs) CYL1-5. Western blot was used to determine the binding ability of five mAbs to the associated antigens released from colorectal cells lysed with single or triplex-detergent, respectively. The mAb with highest binding ability was employed as the ligand for the immuno-affinity chromatography. The antigens purified through immuno-affinity chromatography were identified by Western blot. RESULTS: The associated antigens were highly expressed on the colorectal cancer cell lines Hce-8693. The binding ability of mAb CYL-2 to the antigen was higher than that of CYL-1, CYL-3-5. The purified associated antigen binding to mAb CYL-2 was a heterodimer composed of two subunits with relative molecular mass (M(r)) of 60 x 10(3) and 70 x 10(3), respectively. CONCLUSION: The purified associated-antigen binding to mAb CYL-2 was obtained from the colorectal cancer cell line Hce-8693 through immuno-affinity chromatography with mAb CYL-2.

Antibodies, Monoclonal↗
PubMed2004

[DSRAD gene mutations in three families with dyschromatosis symmetrica hereditaria].

OBJECTIVE: To identify the DSRAD gene; mutations in three Chinese families with dyschromatosis symmetrica hereditaria. METHODS: All exons of DSRAD gene were analyzed in each person of these families with PCR-DNA sequencing. DNA samples from 100 unrelated, normally pigmented adult individuals were also included as control. RESULTS: We identified a missense mutation of C3220T (R1074C) in DSRAD gene in family A, and another missense mutation of G3325T (D1109Y) in DSRAD gene in family B and C. No same mutation was found in unaffected individuals in the families and the controls. CONCLUSION: We found two special missense mutations in DSRAD gene in three families of dyschromatosis symmetrica hereditaria. These mutations may impair DSRAD protein function, and as a consequence, cause skin dyschromatosis.

Adenosine Deaminase↗
PubMed2004

[Research advances of genodermatosis in China].

Research in the field of genetic skin disease has grown rapidly over the past two decades. Even though the fundamental molecular pathways are still not fully understood, there have prominent advances in our understanding of the underlying mechanisms involved in the pathogenesis of genodermatosis. Dermatologists in China contributed to this field in recent years. They found the causative genes involved in primary erythermalgia and familial trichoepithelioma. Different gene mutations involved in more than twenty kinds of genodermatosises have been detected. This review will synthesize recent findings of the genodermatosises in China.

China↗
PubMed2004

Comparison of dual-energy X-ray absorptiometry machines for measuring fat distribution changes of HIV-associated lipodystrophy.

BACKGROUND: Dual-energy X-ray absorptiometry (DXA) is regarded as a useful objective method for diagnosis of HIV-associated lipodystrophy (LD). OBJECTIVE: To determine whether the use of different DXA machines may affect the diagnosis of LD. METHODS: Body composition in 24 HIV-infected patients, 12 of whom had clinically diagnosed LD, was measured on two DXA machines (Lunar and Hologic). RESULTS: Hologic gave significantly higher values than Lunar DXA for total body fat percent (22.9 vs 20.5%, P<0.001), arm fat percent (27.9 vs 14.5%, P<0.001) and leg fat percent (23.4 vs 17.5%, P<0.001), and significantly lower values than Lunar for trunk fat percent (22.3 vs 24.7%, P<0.001) and trunk-to-limb fat percent ratio (0.89 vs 1.62, P<0.001). When measured by Lunar, patients with LD had significantly lower leg fat percent (13.5 vs 21.6%, P=0.04) and higher trunk-to-limb fat percent ratio (1.85 vs 1.38; P=0.012) than those without LD. When measured by Hologic, patients with LD had values of leg fat percent (20.1 vs 26.8%, P=0.11) and trunk-to-limb fat percent ratio (0.95 vs 0.85, P=0.43) that did not differ significantly from those without LD. There was a significant difference in the contribution to a composite LD score between Lunar and Hologic measurements. CONCLUSION: DXA machines from different manufacturers give major differences in measurements of body fat content and distribution, and this may affect the ability to distinguish patients with LD from those without LD. Further standardization of DXA technology is needed before widespread application in the clinical diagnosis of LD.

Absorptiometry, Photon↗
PubMed2003

DNA bending and unbending by MutS govern mismatch recognition and specificity.

DNA mismatch repair is central to the maintenance of genomic stability. It is initiated by the recognition of base-base mismatches and insertion/deletion loops by the family of MutS proteins. Subsequently, ATP induces a unique conformational change in the MutS-mismatch complex but not in the MutS-homoduplex complex that sets off the cascade of events that leads to repair. To gain insight into the mechanism by which MutS discriminates between mismatch and homoduplex DNA, we have examined the conformations of specific and nonspecific MutS-DNA complexes by using atomic force microscopy. Interestingly, MutS-DNA complexes exhibit a single population of conformations, in which the DNA is bent at homoduplex sites, but two populations of conformations, bent and unbent, at mismatch sites. These results suggest that the specific recognition complex is one in which the DNA is unbent. Combining our results with existing biochemical and crystallographic data leads us to propose that MutS: (i) binds to DNA nonspecifically and bends it in search of a mismatch; (ii) on specific recognition of a mismatch, undergoes a conformational change to an initial recognition complex in which the DNA is kinked, with interactions similar to those in the published crystal structures; and (iii) finally undergoes a further conformational change to the ultimate recognition complex in which the DNA is unbent. Our results provide a structural explanation for the long-standing question of how MutS achieves mismatch repair specificity.

Adenosine Triphosphatases↗
PubMed2003

[Effects of macrophage infiltration and related gene expression on the pathogenesis of early abdominal aortic aneurysm].

OBJECTIVE: To detect the pathogenic mechanism of early abdominal aortic aneurysm (AAA). METHODS: Pig elastinase was perfused into the abdominal aortae of 40 Wistar rats to construct AAA animal models. The diameter of abdominal aorta was measured and then the abdominal aorta was harvested from 10 rats on the postoperative days 3, 7, 14, and 28 respectively. The thoracic aorta was used as control. HE staining, elastic staining, and CD68 (macrophage specific antigen) immunohistochemical staining were used to detect the distribution of elastic fiber and macrophage infiltration in aortic tissue. In situ hybridization was applied to investigate the mRNA expression of monocyte chemotactic protein-1 (MCP-1) and matrix metalloproteinase-2 (MMP-2). RESULTS: Three days after the operation, the expansion of abdominal aorta began to be seen and peaked 2 weeks after operation. Disruption of elastic fiber began to be found in the wall of abdominal aorta since 3 approximately 7 days after operation, and reached the maximum 2 weeks postoperatively. CD68 positive cell was not found in the wall of normal thoracic aorta and began to be found in the wall of abdominal aorta 3 approximately 7 days after operation. The expression of CD68 protein peaked on the day 14 with a significant difference from that on day 3 (t = 5.13, P < 0.01). The number of CD58 positive cells was remarkably decreased 4 weeks after operation in comparison with that 2 weeks after operation (t = 4.27, P < 0.01). The mRNA expression rates of MCP-1 and MMP-2 in the wall of abdominal aorta were at their maximal values, (31.5 +/- 5.7)% and (35.2 +/- 7.8)%, on the postoperative days 7 and 14 respectively, significantly higher than those at other time points (all P < 0.01). The MCP-1 and MMP-2 positive cells began to decrease since the 4th postoperative week. CONCLUSION: Macrophage infiltration is parallel to MMP-2 mRNA expression and elastic fiber disruption in aortic tissue. MCP-1 mRNA expression, as a promoting factor, induces the macrophage infiltration, thus contributing to the development and progression of AAA.

Animals↗
PubMed2003

[The relationship between hypoxia inducible factor-1 alpha expression and novoendotheliasis after autogenous vein grafting].

OBJECTIVE: To elucidate the relationship between the level of hypoxia inducible factor-1alpha (HIF-1alpha) expression and novoendotheliasis after autogenous vein grafting. METHODS: 40 Wistar rats underwent right internal jugular vein to common jugular artery interposition grafting. Twenty rats were killed 7 and 14 days after the grafting respectively and the grafted veins were harvested respectively. Twenty rats not undergoing grafting were used as controls. The expressions of HIF-1alpha mRNA and protein and vascular endothelial growth factor (VEGF) mRNA and protein were examined by using reverse transcription polymerase chain reaction, Western blotting, and immunohistochemistry. Electron microscope was used to observe the process of vascular novoendotheliasis. RESULTS: The percentage of HIF-1alpha positive cells 7 days after grafting was 20.5 +/- 6.2%, significantly higher than that 14 days after (12.3 +/- 3.7, P < 0.01) and that of the controls (0.5 +/- 0.1%, P < 0.01). The percentage of HIF-1alpha positive cells 14 days after grafting was significantly higher than that of the controls too (P < 0.01). The expression of HIF-1alphamRNA 7 days after grafting was 53.2 +/- 9.3, significantly higher than that 14 days after grafting (43.2 +/- 6.3, P < 0.01) and that in the control (29.4 +/- 5.6, P < 0.01). The expression of HIF-1alpha7 mRNA 14 days after grafting was significantly higher than that of the controls too (P < 0.01). The expression of HIF-1alpha protein 7 days after grafting was 5.6 +/- 0.4, significantly higher than that 14 days after grafting (3.5 +/- 0.2, P < 0.01) and that in the control (0.8 +/- 0.1, P < 0.01). The expression of VEGF protein 7 days after grafting was 2.2 +/- 0.1, significantly higher than that of the control (0.5 +/- 0.1, P < 0.01). Novoendotheliasis was seen 7 days after grafting and decreased 14 days after. The expression of HIF-1alpha was positively correlated with the expression of VEGF (r = 0.903, P < 0.01). CONCLUSION: HIF-1 alpha is closely related to novoendotheliasis. The deficiency of HIF-1 alpha expression plays an important role in intima hyperplasia.

Animals↗
PubMed2003

Incorporating leaf transmission and head scatter corrections into step-and-shoot leaf sequences for IMRT.

PURPOSE: Leaf transmission and head scatter are two important factors that influence intensity-modulated radiation therapy (IMRT) delivery and should be correctly taken into account when generating multileaf collimator (MLC) sequences. Significant discrepancies between the desired and delivered intensity profiles could otherwise result. The purpose of this article is to propose a reliable algorithm to minimize the dosimetric effects caused by the two factors in step-and-shoot mode. MATERIALS AND METHODS: The goal of the algorithm is to minimize the difference between the desired fluence map and the fluence map actually delivered. For this purpose, an error function, defined as the least-square difference between the desired and the delivered fluence maps, is introduced. The effects of transmission and head scatter are minimized by adjusting the fractional monitor units (MUs) in the initial MLC sequences, created by using the desired fluence map without inclusion of the contributions from the two factors. Computationally, a downhill simplex optimization method is used to minimize the error function with respect to the fractional MUs. A three-source model is used to evaluate the relative head scatter distribution for each segment at the beginning of the calculation. The algorithm has been assessed by comparing the dose distributions delivered by the corrected leaf sequence files and the theoretic predication, calculated by Monte Carlo simulation using the desired fluence maps, for an intuitive test field and several clinical IMRT cases. RESULTS: The deviations between the desired fluence maps and those calculated using the corrected leaf sequence files are <0.3% of the maximum MU for the test field and <1.0% for the clinical IMRT cases. The experimental data show that both absolute and relative dose distributions delivered by the corrected leaf sequences agree with the desired ones within 2.5% of the maximum dose or 2 mm in high-dose gradient regions. Compared with the results obtained by using the leaf sequences in which only the transmission or none of the two effects is corrected, significant improvements in the fluence and dose distributions have been observed. CONCLUSIONS: Transmission and head scatter play important roles in the dosimetric behavior of IMRT delivery. A larger error may result if only one factor is considered because of the opposite effects of the two factors. We noted that the influence of the two effects is more pronounced in absolute dose than in the relative dose. The algorithm proposed in this work accurately corrects for these two effects in step-and-shoot delivery and provides a reliable tool for clinical IMRT application.

Algorithms↗
PubMed2003

Quantitative characterization of biomolecular assemblies and interactions using atomic force microscopy.

Atomic force microscopy (AFM) has been applied in many biological investigations in the past 15 years. This review focuses on the application of AFM for quantitatively characterizing the structural and thermodynamic properties of protein-protein and protein-nucleic acid complexes. AFM can be used to determine the stoichiometries and association constants of multiprotein assemblies and to quantify changes in conformations of proteins and protein-nucleic acid complexes. In addition, AFM in solution permits the observation of the dynamic properties of biomolecular complexes and the measurement of intermolecular forces between biomolecules. Recent advances in cryogenic AFM, AFM on two-dimensional crystals, carbon nanotube probes, solution imaging, high-speed AFM, and manipulation capabilities enhance these applications by improving AFM resolution and the dynamic and operative capabilities of the AFM. These developments make AFM a powerful tool for investigating the biomolecular assemblies and interactions that govern gene regulation.

Air↗
PubMed2003

Using the volumetric effect of a finite-sized detector for routine quality assurance of multileaf collimator leaf positioning.

Intensity modulated radiation therapy (IMRT) is an advanced form of radiation therapy and promises to improve dose conformation while reducing the irradiation to the sensitive structures. The modality is, however, more complicated than conventional treatment and requires much more stringent quality assurance (QA) to ensure what has been planned can be achieved accurately. One of the main QA tasks is the assurance of positioning accuracy of multileaf collimator (MLC) leaves during IMRT delivery. Currently, the routine quality assurance of MLC in most clinics isbeing done using radiographic films with specially designed MLC leaf sequences. Besides being time consuming, the results of film measurements are difficult to quantify and interpret. In this work, we propose a new and effective technique for routine MLC leaf positioning QA. The technique utilizes the fact that, when a finite-sized detector is placed under a leaf, the relative output of the detector will depend on the relative fractional volume irradiated. A small error in leaf positioning would change the fractional volume irradiated and lead to a deviation of the relative output from the normal reading. For a given MLC and detector system, the relation between the relative output and the leaf displacement can be easily established through experimental measurements and used subsequently as a quantitative means for detecting possible leaf positional errors. The method was tested using a linear accelerator with an 80-leaf MLC. Three different locations, including two locations on central plane (X1 = X2 = 0) and one point on an off-central plane location (X1 = -7.5, X = 7.5), were studied. Our results indicated that the method could accurately detect a leaf positional change of approximately 0.1 mm. The method was also used to monitor the stability of MLC leaf positioning for five consecutive weeks. In this test, we intentionally introduced two positional errors in the testing MLC leaf sequences: -0.2 mm and 1.2 mm. The technique was found to be robust and could detect the positional inaccuracy in each week's test. The influence of other possible error sources, including the ion chamber placement, jaw settings, gantry and collimator angle read-outs, and the positioning errors of the adjacent leaves, on detection accuracy were also investigated. The principle of our method is independent of the types of the MLC and the detector and may have significant practical implications in facilitating routine MLC QA for IMRT delivery.

Calibration↗