Biomedical subjects

Q J Wu

Publications and source records attributed to Q J Wu.

12 recordsLinked to original sources

PubMed2001

Synthesis and structural characterization of the novel cluster compound.

Reaction of [Mo3Y(mu-S)3(dtp)4(H2O)] (Y = O, S; dtp = S2P(OC2H5)2(-)) with HgI2 gave the novel compound [[Mo3S7(dtp)3]4 x I][(HgI3)3] x 4H2O (1), which contains a [[Mo3S7(dtp)3]4 x I] tetramer and (HgI3)-. Compound 1 has been characterized by IR, Raman, UV/Vis, and NMR spectroscopy and single-crystal X-ray diffraction analysis. It is shown that this formation process can be referred to as a new cluster reaction. The structure and spectroscopic data of the tetramer is also compared with that of the related discrete cluster [Mo3S7(dtp)3 x I]. Crystal data: space group F23, a = 26.786(3) A, V = 19218.7(4) A3, Z = 4, R = 0.059.

Journal Article↗

PubMed2000

Synthesis and characterization of three tetranuclear clusters containing a [Mo3OS3Sn]6+ cubane-like core.

Three heterometallic cubane-like clusters, [Mo3(mu 3-O)(mu 3-S)3(SnCl3)(dtp)3(py)3] (dtp = S2P(OC2H5)2-, py = C5H5N) (1), (PPN)[Mo3(mu 3-O)(mu 3-S)3(SnCl3)(dtp)3(mu-OAc)(py)] (OAc = CH3COO-, PPN = (C6H5)3PNP(C6H5)3+) (2), and (Et4N)[Mo3(mu 3-O)(mu 3-S)3(SnCl3)(dtp)2(mu-OAc)2(py)] (3) have been prepared by the reaction of [Mo3(mu 3-O)-(mu-S)3(dtp)4(H2O)] (4), [Mo3(mu 3-O)(mu-S)3(dtp)3(OAc) (py)] (5), and [Mo3(mu 3-O)(mu-S)3(dtp)2(OAc)2 (py)] (6) with SnCl2, respectively. They have been characterized by IR, UV-vis, 31P NMR, 95Mo NMR, and X-ray structure analysis. All of these heterometallic clusters have a [Mo3OS3Sn]6+ core but contain a different arrangement of peripheral ligands. As far as the neutral cluster 1 is concerned, there is no bridging OAc ligand, while only one bridging OAc ligand is observed for cluster 2 and two are for cluster 3. The Mo-Mo distances are about 0.03-0.04 A shorter than those of the starting trimolybdenum clusters. This indicates that the incorporation of SnCl3- fragment into (Mo3) clusters makes the Mo-Mo bonding enhanced. Crystal data for 1: triclinic, space group P-1, a = 10.7423(2) A, b = 14.0357(1) A, c = 16.9346(2) A, alpha = 84.054(1) degrees, beta = 87.095(1) degrees, gamma = 84.517(1) degrees, V = 2525.82(6) A3, Z = 2, R = 0.038 for 5584 reflections (I > 2.0 sigma(I)). Crystal data for 2: triclinic, space group P-1, a = 12.9529(1) A, b = 15.6324(2) A, c = 19.6355(1) A, alpha = 92.083(1) degrees, beta = 97.908(1) degrees, gamma = 110.337(1) degrees, V = 3677.41(6) A3, Z = 2, R = 0.034 for 8665 reflections (I > 2.0 sigma(I)). Crystal data for 3: monoclinic, space group P2(1)/n, a = 14.0852(5) A, b = 15.1324(5) A, c = 23.2691(7) A, beta = 97.371(1) degrees, V = 4918.7(3) A3, Z = 4, R = 0.049 for 4970 reflections (I > 2.0 sigma(I)).

Journal Article↗

PubMed2000

GammaPlan-Leksell Gamma Knife radiosurgery treatment planning verification method.

This work provides a method for an independent check of Gamma Knife GammaPlan radiosurgery calculations, named the spherical approximation method or SAM. Based on skull dimension measurements, the treated volume of the head is modeled as a sphere of radius R. With this approximation, an analytical solution for fast ray tracing of the path length, for each of the 201 beamlets, of the Gamma Knife helmet collimator was possible. The dose rate at the focus of a single shot is the sum of the contributions of all active beamlets adjusted for both the collimator factor and attenuation. For an arbitrary point, the dose rate is derived at the beamlet level from the focus values adjusted for the new path length attenuation and the appropriate collimators' off-axis profiles. The sum over all beamlets' contributions gives the dose rate at that particular point. At the single shot level, SAM independent check results agree with the GammaPlan for patient calculations to better than +/-6% and, as expected, in spherical phantoms the agreements improve to better than +/-1.0%. For an arbitrary point, multi-shot procedure, the agreement is better than +/-3% and +/-1.5, respectively.

Humans↗

PubMed2000

Fast verification of Gamma Knifetrade mark treatment plans.

The Leksell stereotactic Gamma Knifetrade mark uses radiation from 201 (60)Co sources that are focused to the center of a collimator helmet to deliver a high dose of radiation with minimal irradiation of proximal structures. This paper presents a method for fast verification of the irradiation time as calculated by the Leksell Gamma Knifetrade mark treatment planning software GammaPlan((R)). To obtain the irradiation time for each shot in the treatment plan, one must first accurately calculate the tissue maximum ratio (TMR) for each of the individual 201 beams. The algorithm presented in this paper begins with the determination of the geometrical relationship between the Gamma Knifetrade mark collimator helmet and the stereotactic frame. A group of reference points is measured to build a head model simulating the patient skull geometry. During radiosurgery, the isocenter of the collimator helmet is moved to the shot center. A group of spatial vectors describing the reference points at the skull surface is obtained by converting the Cartesian coordinates to Polar coordinates. For each individual beam, the three nearest reference vectors are found by ranking the relative angles. The depth that each beam penetrates the patient's skull to the isocenter is obtained via linear interpolation. The TMR for each beam then is compared with the TMR for the calibration setup, which is done using a spherical 8 cm radius phantom. This algorithm is applied to verify the treatment time calculated in GammaPlan((R)) Version 5.2. The results are shown to agree with GammaPlan((R)) within 3%.

Algorithms↗

PubMed2000

[The expression patterns of genes in different biotypes by genome addition].

The patterns of SOD, EST and haemoglobin genes expression among the different combinations conducted with genome addition were investigated. The erythrocyte expression of these isozymes and protein were visualized by histochemical staining after polyacrylamide gradient gel electrophoresis. The results of our electrophoresis analysis have revealed that biochemical polymorphism exists in the combinations, and these genetic variance have resulted from the contribution of different genomes. This study provides additional evidence that gene dosages can be interpreted from the enzyme patterns and electrophoretic staining intensities existed in different ploidies, which suggests that subunit interactions for SOD are co-operative and additive. This would indicate that each allele could be differentially regulated so that even one-third genome can be expressed in triploid individuals. These genetic data could be used to construct genome specific varieties, and would not only help to maximize efficiency in the use of different biotypes identification, but also help to maximize studying the relationship between gene dosage, expression and regulation.

Animals↗

PubMed1999

Morphology-guided radiosurgery treatment planning and optimization for multiple isocenters.

This work merges two distinct fields, 3D morphology and ionizing radiation dosimetry, to solve the problem of 3D-treatment planning and optimization in stereotactic radiosurgery. In Leksell Gamma Knife radiosurgery, dose delivery is based on the unit "shot," a dose distribution approximately spherical in shape. Multiple shots, or isocenters, are used in Gamma Knife treatment to deliver a conformal dose to an irregular radiosurgical target. The medial axis transformation, or skeleton, of the target, which uniquely characterizes the target volume and shape, is used to determine the optimal shot positions (isocenters), sizes (collimator helmet size and dosimetric weight), and the total number of shots that will deliver a conformal dose distribution to the target. The skeletonization approach reduces a complicated 3D-optimization problem to 1D searching with potential savings in computation time and mathematical complexity. In addition, optimization based on target shape replicates and automates manual treatment planning. This approach makes the process easily understandable. The relationship between skeleton discs and the dose distributions they predict is discussed. Results of optimal plans and corresponding dose distributions are presented. This approach is generally applicable to other types of multi-isocentric stereotactic radiosurgery techniques.

Bone and Bones↗

PubMed1999

[Mitochondrial DNA length variation and heteroplasmy in Chinese sturgeon (Acipenser sinensis)].

The D-loop of mitochondrial DNA from Chinese sturgeon (Acipenser sinensis) was amplified using PCR. The length variations among individuals and within individual (heteroplasmy) were detected. DNA sequence analysis revealed that interindivadual and intraindividual length variation occurred within D-loop near tRNA(pro), and caused by tandam repeat with 82 bp in length. Out of 47 individuals, 27(57.4%) individuals were heteroplasmy whereas 20 individual (42.6%) were homoplasmic. The length variation was also found among homoplasmic individuals. In homoplasmic individual four different size classes (number of tandem repeats) e.g. 2, 3, 4 or 5 repeats were noted. The frequencies of size classes from the highest to the lowest were 3-->2-->4-->5. In heteroplasmy two molecular size classes coexisted in an individual was most common (77.78%). The second type of heteroplasmy was three size classes coexisted (18.52%) and the lowest one was four size classes together in an individual (3.70%). No five different size classes coexisted in an individual was found. Through densitometry of DNA bands the frequencies of mtDNA size classes were determined for the sample of individuals, and the frequency distribution of repeats from the highest to the lowest was similar to that in homoplasmy (3-->2-->4-->5-->1). The diversity within each heteroplasmic individual was carried out and genetic diversity at hierarchical level was analyzed. 65.3% of genetic diversities were from among individuals in population and 34.7% of genetic diversities were from within individual. The mtDNA length variation within individual (heteroplasmy) is another genetic diversity resource for Chinese sturgeon.

Animals↗

PubMed1992

[The crystal structure of triptophenolide revisited].

Triptophenolide, C20H24O3, has been assigned two isomeric structures. DF Yu et al reported the X-ray analytical structure II in 1990. In 1982, however, FX Deng et al had already reported the spectrometric assignment of structure I. Now, we report again the single crystal analysis of triptophenolide (I). The crystal belongs to space group P2(1)2(1)2(1) of orthorhombic system, with a = 7.270(6), b = 12.509(8), c = 36.20(1) A, Z = 8. The structure was solved by direct method and refined by the full-matrix least-square method to a final R factor 0.055, based on 2322 intensities with I > or = 3 sigma (I). It is highly probable that the result of DF Yu was in error with only 1292 available intensities.

Crystallography↗

PubMed1992

[Studies on the triterpenoid saponin of Cinopodium chinense (Benth) O. Kuntze].

A new triterpenoid saponin named clinopodiside was isolated from Clinopodum Chinense (Benth) O. Kuntze. The structure of clinopodiside A was elucidated by spectroscopic and X-ray diffraction analysis as 3-O-beta-D-glucopyranosyl (1----6)-[beta-D-glucopyranosyl (1----4)]-beta-D-glucopyranosyl-olean-11, 13 (18)-diene-3 beta, 16 beta, 23, 28-tetrol.

Drugs, Chinese Herbal↗

PubMed1992

The formation and crystal structure of dihydronitidine and discussion of anticancer mechanism of nitidine cation.

The paper reports the formation and crystal structure of dihydronitidine, expounds the reasons and conditions of easily formed oxynitidine, and discusses anticancer mechanism of nitidine (cation). The crystallographic parameters of dihydronitidine are: space group P(2)1/n, a = 12.54(1), b = 9.148(5), c = 14.748(8) A, beta = 92.12(6)degrees, Z = 4. 4108 independent reflections were collected within the range of 3 degrees < or = 2 theta < or = 54 degrees, of which 2137 intensity data with I > or = 3 sigma (I) were used in the structural determination. The crystal structure has been refined by full matrix least-square method to a final R of 0.050.

Antineoplastic Agents, Phytogenic↗

PubMed1983

Retina of river dolphin Lipotes Vexillifer.

The structure of retina of the Lipotes Vexillifer has been studied quantitatively under light microscope. The results obtained are as follows. (i) The thickness of the retina is 268 micrometer. The lamination of retina can be clearly distinguished. It consists of 10 layers. The thicknesses of the layers from pigment epithelium to internal limiting membrane are 12 micrometer, 44 micrometer, 2 micrometer, 48 micrometer, 20 micrometer, 36 micrometer, 68 micrometer, 32 micrometer, 8 micrometer and 2 micrometer respectively. (ii) The number of cells in the outer nuclear layer is larger than that in the inner nuclear layer. Two types of cell can be distinguished in this layer. The number of receptors and ganglion cells is in a ratio of 12 to 1. These results show that the retina type of the Lipotes corresponds to that of nocturnal animals. (iii) The diameters of ganglion cells range 1.5-37 micrometer with two peaks at 6 micrometer and 35 micrometer. This means that the ganglion cells fall into two groups according to size, and this has been proved by the observation on morphology of ganglion cells in the whole-mount preparation and sections of the retina. The percentages of large cells and small cells are 3% and 97% respectively. The proportion of small cells to large cells does not change greatly in different parts of the retina. (iv) No fovea and visual streak have been found in the retina.

Animals↗

PubMedDate not supplied

Three-dimensional skeletonization for computer-assisted treatment planning in radiosurgery.

This paper describes a new algorithm for skeletonization of two- (2D) and three-dimensional (3D) objects based on ridge extraction. Ridges are formed when grassfire fronts collapse during grassfire propagation and they correspond to the locus of skeleton. The iso-distance contours/surfaces of a distance map are analogous to the grassfire fronts. They are locally smooth everywhere except at ridge locations. The new skeletonization algorithm extracts these ridge points based on local curvature measurement and is rotational invariant. It requires one scan of the image for curvature detection in any dimension, and is much faster than thinning methods. Connectivity checks are not required and the algorithm is extensible to higher dimensions. Our 3D skeletonization method is used in a novel algorithm to guide computerized planning of radiosurgical treatment of brain tumors.

Algorithms↗