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Biomedical subjects

Jing Yang

Publications and source records attributed to Jing Yang.

At least 145 records · Page 8Linked to original sources
PubMed2004

Leukemic cell intracellular responses to nanosecond electric fields.

Intense, nanosecond (ns) pulsed electric fields (PEFs) are known to affect the intracellular structures of cells. The probability of preferentially inducing subcellular effects increases with decreasing pulse length while effects on the plasma membrane are diminished. This has been demonstrated by applying electrical pulses of 60 and 10 ns duration with electric field intensities of up to 6.5 MV/m to HL-60 cells. Using confocal microscopy, PEF-induced changes in the integrity of the plasma membrane and nucleus were measured by recording fluorescence changes with propidium iodide (PI) and acridine orange (AO), respectively. Results suggest that high voltage, nsPEFs target the nucleus and modify cellular functions while plasma membrane effects are delayed and become smaller as pulse duration is shortened. Cell viability was not affected by these pulses. In spite of the high pulsed electric fields, thermal effects can be neglected because of the ultrashort pulse duration. The results suggest application of this ultrashort pulse technology to modulate nuclear structure and function for potential therapeutic benefit.

Adaptation, Physiological↗
PubMed2004

Visible fluorescent detection of proteins in polyacrylamide gels without staining.

2,2,2-Trichloroethanol (TCE) incorporated into polyacrylamide gels before polymerization provides fluorescent visible detection of proteins in less than 5min of total processing time. The tryptophans in proteins undergo an ultraviolet light-induced reaction with trihalocompounds to produce fluorescence in the visible range so that the protein bands can be visualized on a 300-nm transilluminator. In a previous study trichloroacetic acid or chloroform was used to stain polyacrylamide gel electrophoresis (PAGE) gels for protein visualization. This study shows that placing TCE in the gel before electrophoresis can eliminate the staining step. The gel is removed from the electrophoresis apparatus and placed on a transilluminator and then the protein bands develop their fluorescence in less than 5min. In addition to being rapid this visualization method provides detection of 0.2microg of typical globular proteins, which for some proteins is slightly more sensitive than the standard Coomassie brilliant blue (CBB) method. Integral membrane proteins, which do not stain well with CBB, are visualized well with the TCE in-gel method. After TCE in-gel visualization the same gel can then be CBB stained, allowing for complementary detection of proteins. In addition, visualization with TCE in the gel is compatible with two-dimensional PAGE, native PAGE, Western blotting, and autoradiography.

Acrylic Resins↗
PubMed2004

Drosophila ninaB and ninaD act outside of retina to produce rhodopsin chromophore.

The Drosophila ninaB gene encodes a beta,beta-carotene-15,15'-oxygenase responsible for the centric cleavage of beta-carotene that produces the retinal chromophore of rhodopsin. The ninaD gene encodes a membrane receptor required for efficient use of beta-carotene. Despite their importance to the synthesis of visual pigment, we show that these genes are not active in the retina. Mosaic analysis shows that ninaB and ninaD are not required in the retina, and exclusive retinal expression of either gene, or both genes simultaneously, does not support rhodopsin biogenesis. In contrast, neuron-specific expression of ninaB and ninaD allows for rhodopsin biogenesis. Additional directed expression studies failed to identify other tissues supporting ninaB activity in rhodopsin biogenesis. These results show that nonretinal sites of NinaB beta,beta-carotene-15,15'-oxygenase activity, likely neurons of the central nervous system, are essential for production of the visual chromophore. Retinal or another C(20) retinoid, not members of the beta-carotene family of C(40) carotenoids, are supplied to photoreceptors for rhodopsin biogenesis.

Animals↗
PubMed2004

Transient mixed-valence character of Re(I)(4)(CO)(12)(4,4'-bpy)(4)Cl(4).

This study addresses, in detail, the orbital nature and the extent of metal-metal communication in the lowest emitting triplet state of Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) (where 4,4'-bpy = 4,4'-bipyridine) as well as the symmetry of the lowest (3)MLCT manifold in comparison to that of the ground state. All spectral evidence points to (1). a (3)MLCT excited manifold localized between a single Re(I) corner and an adjacent bridging ligand, (2). a transient mixed-valence state that is completely localized between a single transiently oxidized Re center and the adjacent metals, and (3). a second-order charge transfer from a localized transiently reduced bridging ligand to the adjacent Re(I) center to which it is attached, effectively lowering its oxidation state. The orbital nature of the lowest (3)MLCT manifold is fully corroborated by a molecular orbital diagram derived from quantum chemical modeling studies, while the existence of the localization, localized mixed valency, and second-order charge transfer rely on spectral evidence alone. This work makes use of low-temperature time-resolved infrared (TRIR) techniques as well as a luminescence study. Many of the nuances of the luminescence and TRIR data interpretation are extracted from statistical analysis and quantum chemical modeling studies. The relative concentrations of the dominant conformers that exist for Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) have also been estimated from Boltzmann statistics.

Journal Article↗
PubMed2004

[The effect of vascular endothelia growth factor encapsulated in nanoparticles on chronic limb ischemia].

OBJECTIVE: To experimentally investigate direct intramuscular gene transfer of nanoparticles encoding vascular endothelial growth factor for the treatment of peripheral artery disease. METHODS: The human VEGF(165) cDNA was cloned into the eukaryotic expression vector PIRES2 under the control of cytomegalovirus promoter/enhancer. The recombinant gene was transferred into a rabbit model of chronic hindlimb ischemia by naked plasmid and nanoparticle respectively. Ischemia was induced in the hindlimb of New Zealand White rabbits by ligation of the distal external iliac artery and complete excision of the femoral artery and all its branches. At day 7 postoperation animals received VEGF(165) plasmid (10 intramuscular) or nanoparticle-VEGF(165) (8 intramuscular). With RT-PCR, immunohistochemistry analysis, and angiography, the expression and biological effects of VEGF(165) gene in experimental animals were investigated. RESULTS: Two weeks after initiation of therapy, angiography showed that the transfer of VEGF(165) gene stimulated the formation of focal neovessels and established collateral circulation. The adductor muscle of ischemic limbs was histologically examined at day 14. Capillary density was increased among VEGF(165)-transfected rabbits, especially Nano-VEGF(165)-treated animals (Naked VEGF(165) plasmid = 50.18 per mm(2), Nano-VEGF(165) = 81.22 per mm(2), Control = 29.54 per mm(2), P < 0.05). RT-PCR showed that the transcription and expression of VEGF(165) gene in experimental group were significantly higher than those of control groups. CONCLUSIONS: Intramuscular administration of VEGF(165) induces collateral artery augmentation in the rabbit model of chronic limb ischemia. Nanoparticle can act as a vector to transfect specific gene and it will benefit gene transfer.

Angiography↗
PubMed2004

3D image segmentation of deformable objects with joint shape-intensity prior models using level sets.

We propose a novel method for 3D image segmentation, where a Bayesian formulation, based on joint prior knowledge of the object shape and the image gray levels, along with information derived from the input image, is employed. Our method is motivated by the observation that the shape of an object and the gray level variation in an image have consistent relations that provide configurations and context that aid in segmentation. We define a maximum a posteriori (MAP) estimation model using the joint prior information of the object shape and the image gray levels to realize image segmentation. We introduce a representation for the joint density function of the object and the image gray level values, and define a joint probability distribution over the variations of the object shape and the gray levels contained in a set of training images. By estimating the MAP shape of the object, we formulate the shape-intensity model in terms of level set functions as opposed to landmark points of the object shape. In addition, we evaluate the performance of the level set representation of the object shape by comparing it with the point distribution model (PDM). We found the algorithm to be robust to noise and able to handle multidimensional data, while able to avoid the need for explicit point correspondences during the training phase. Results and validation from various experiments on 2D and 3D medical images are shown.

Algorithms↗
PubMed2004

Geometric strategies for neuroanatomic analysis from MRI.

In this paper, we describe ongoing work in the Image Processing and Analysis Group (IPAG) at Yale University specifically aimed at the analysis of structural information as represented within magnetic resonance images (MRI) of the human brain. Specifically, we will describe our applied mathematical approaches to the segmentation of cortical and subcortical structure, the analysis of white matter fiber tracks using diffusion tensor imaging (DTI), and the intersubject registration of neuroanatomical (aMRI) data sets. Many of our methods rally around the use of geometric constraints, statistical (MAP) estimation, and the use of level set evolution strategies. The analysis of gray matter structure and connecting white matter paths combined with the ability to bring all information into a common space via intersubject registration should provide us with a rich set of data to investigate structure and variation in the human brain in neuropsychiatric disorders, as well as provide a basis for current work in the development of integrated brain function-structure analysis.

Algorithms↗
PubMed2004

Intein harbouring large tandem repeats in replicative DNA helicase of Trichodesmium erythraeum.

Protein splicing inteins can be small as approximately 130 aa or up to approximately 600 aa when harbouring an endonuclease domain. Here we report the identification and characterization of an unusually large intein, 1650 aa long and the largest of known inteins, encoded by the replicative DNA helicase gene dnaB of the oceanic N2-fixing cyanobacterium Trichodesmium erythraeum. This Ter DnaB-1 intein co-exists with a 177-aa mini-intein in the same host protein and harbours large tandem repeats in which an 84-aa sequence is repeated 16 times. Comparison between this tandem repeats and the recently reported tandem repeats of Ter DnaE-1 intein revealed differences and similarities. The two tandem repeats, residing in different inteins of different host proteins, differ by 50% in size and have little sequence similarity. Tandem repeats in the Ter DnaB-1 intein were required for the protein splicing activity when tested in Escherichia coli, in contrast to tandem repeats of the Ter DnaE-1 intein that inhibited protein splicing. On the other hand, tandem repeats of both inteins are located in the same corresponding region of the intein sequence and have the same number of repeating units. These suggest that the two tandem repeats could be related but have diverged greatly in size, sequence and effect on protein splicing. Alternatively, they could have independent origins but evolved certain similarities because of common constraints in structure and maintenance.

Amino Acid Sequence↗
PubMed2004

Neighbor-constrained segmentation with level set based 3-D deformable models.

A novel method for the segmentation of multiple objects from three-dimensional (3-D) medical images using interobject constraints is presented. Our method is motivated by the observation that neighboring structures have consistent locations and shapes that provide configurations and context that aid in segmentation. We define a maximum a posteriori (MAP) estimation framework using the constraining information provided by neighboring objects to segment several objects simultaneously. We introduce a representation for the joint density function of the neighbor objects, and define joint probability distributions over the variations of the neighboring shape and position relationships of a set of training images. In order to estimate the MAP shapes of the objects, we formulate the model in terms of level set functions, and compute the associated Euler-Lagrange equations. The contours evolve both according to the neighbor prior information and the image gray level information. This method is useful in situations where there is limited interobject information as opposed to robust global atlases. In addition, we compare our level set representation of the object shape to the point distribution model. Results and validation from experiments on synthetic data and medical imagery in two-dimensional and 3-D are demonstrated.

Algorithms↗
PubMed2004

Bacterial thymidylate synthase with intein, group II Intron, and distinctive ThyX motifs.

The ThyX class of thymidylate synthases was previously characterized by a common ThyX motif, RHRX7S. We report bacterial ThyX sequences having distinctive ThyX motifs, suggesting a more general ThyX motif, R/THRX7-8S. One ThyX sequence has an intein in its ThyX motif that was shown to do protein splicing and a group II intron in its gene, suggesting a hot spot for these self-splicing mobile elements.

Amino Acid Motifs↗
PubMed2004

Effects of biological variations on platelet count in healthy subjects in China.

The effects of biological variations on platelet counts were investigated in 694 healthy subjects aged 18 to 60 years living in three cities including Chengdu (Sichuan Province), Suzhou (Jiangsu Province) and Harbin (Heilongjang Province) in China. Platelet counts in healthy subjects were significantly lower in Chengdu (52-202 x 10(9)/L) and Suzhou (60-259 x 10(9)/L) than in Harbin (154-348 x 10(9)/L) (p <0.0001), but the mean platelet volume (MPV) determined concurrently was negatively correlated with platelet count, the MPV values were significantly higher in Chengdu (11.8-15.6 fl) and Suzhou (10.9-15.8 fl) than in Harbin (9.5 approximately 12.9 fl) (p < 0.0001). Platelet counts were significantly higher in summer (73-289 x 10(9)/L) than in winter (52-202 x 10(9)/L) (p <0.0001), but the MPV values were lower in summer (11.2-14.7 fl) than in winter (11.8-15.6 fl) (p <0.05) in Chengdu. Platelet associated immunoglobulin (PA-IgG) in Chengdu was revealed to be significantly higher in the low platelet count group (<150 x 10(9)/L, 13.5 +/- 7.1 ng/10(7) PLT) than in the normal platelet count group (> or =150 x 10(9)/L, 8.3 +/- 2.7 ng/10(7) PLT) (p <0.0001). Similar results were observed in Suzhou for the reticulated platelet ratio, which was significantly higher in the low platelet count group (19.5 +/- 7.1%) than in the normal platelet count group (11.6 +/- 2.7%) (p <0.01). The bleeding time in Chengdu showed a significantly longer time in the low platelet count group (8.6 +/- 2.3 min) than in the normal platelet count group (6.0 +/- 1.2 min)(p <0.01). With regard to the effects of lipids on platelet counts, the HDL values were significantly higher in the normal platelet count group (1.60 +/- 0.76 mmol/L) than the low platelet count group (1.23 +/- 0.31 mmol/L) (p <0.01); but no significant differences in cholesterol and triglycerides values between the normal and low platelet count groups (p >0.05) were recorded. These findings suggest that the platelet counts could be greatly influenced in healthy subjects by biological variations such as geographical, seasonal, and lipid variations.

Adolescent↗
PubMed2004

[Using chamber technique for studying the permeability of dexamethasone sodium phosphate liposome through rabbit colon mucosa in vitro].

OBJECTIVE: To investigate the features of liposome-mediated drug permeability through the colon mucosa in vitro. METHODS: Dexamethasone sodium phosphate liposome (DSP) was prepared using orthogonal design. With in vitro Ussing chamber experiment, the accumulated amount of DSP permeated through rabbit colon mucosa into the receptor chamber and the distribution amount in the colon were determined at different time points during the experiment. RESULTS: Compared with the prepared DSP solution, DSP liposome decreased the permeated amount of DSP through rabbit colon mucosa. The apparent permeability coefficient (Papp, x10(-6), cm/s1) of the DSP was 31.95+/-7.65, significantly lower than that of DSP solution (88.61+/-18.61). On the other hand, the distribution amount of DSP liposome in the colon mucosa was significantly higher than that of the DSP solution both at 120 and 300 min. CONCLUSIONS: DSP liposome dosage form may induce less toxicity with better therapeutic effect in the treatment of colitis, which is worthy of further exploitation.

Animals↗
PubMed2004

[Clinical study on value of severity of patient with coronary artery disease evaluated with the thrombosis in myocardial infarction risk score].

OBJECTIVE: To explore the value of severity evaluating and outcome predicting on coronary artery disease (CAD) patients scored with the thrombosis in myocardial infarction (TIMI) risk score. METHODS: All of 126 patients with CAD were enrolled in study. TIMI risk score and coronary artery angiographic in them were performed respectively. Correlativity between TIMI risk score and clinical type of CAD, narrow severity, pathological changes limits and character of coronary artery were analyzed. Difference of scores of TIMI, narrow severity, pathological changes limits and character of coronary artery were compared among stable angina (SA), unstable angina (UA), un-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI) respectively. RESULTS: TIMI risk score significantly correlated with clinical type of CAD score, narrow severity score, pathological changes limits and character scores of coronary artery respectively (r=0.607 for narrow severity score, 0.569 for pathological changes limits score, 0.367 for pathological changes character score, all P<0.05). TIMI risk score increased company with severity of coronary artery pathological changes advancing. Significantly differences were found when TIMI risk scores were compared between SA and UA, NSTEMI and STEMI respectively as well as narrow severity scores (all P<0.05). Same RESULTS: were found between UA and NSTEMI, STEMI respectively (all P<0.05). There had no significantly difference among pathological changes limits scores of SA, UA, NSTEMI, STEMI (all P>0.05). Significantly difference was found when pathological changes character scores were compared between SA and UA, NSTEMI, STEMI respectively as well as narrow severity scores (P<0.05), but contrary RESULTS: were found between UA and NSTEMI, STEMI respectively (P>0.05). CONCLUSION: TIMI risk score not only could be used to predict the possibility of heart accident, but also could be used to evaluate clinical type of CAD, narrow severity, pathological changes limits and character of coronary artery in CAD patient.

Adult↗
PubMed2004

[Protective effect of berberine on cardiac hypertrophy induced by L-thyroxine in rats].

OBJECTIVE: To assess the effects of berberine on cardiac hypertrophy induceded by L-thyroxine(L-Thy) in rats. METHODS: A cardiac hypertrophy model was produced by intraperitoneal (i.p.) injection of L-thyroxine 0.5 mg/(kg.d) x 10 d. 24 SD rats were divided into three groups: 1. control (normal saline); 2. L-Thy; 3. i.p. L-Thy + berberine gastrogavage 30 mg/(kg.d) x 10 d. Then the cardiac indexes, Na(+)-K(+)-ATPase activity, Ca(2+)-ATPase activity, the cardiac nitric oxide (NO) content, and the CaN activity were measured. RESULTS: Compared with the measurements in the control group, the cardiac indexes and the CaN activity were remarkably increased in the hypertrophy group (P < 0.01), but the cardiac NO content, Na(+)-K(+)-ATPase activity and Ca(2+)-ATPase activity in myocardium were significantly decreased (P < 0.01). Further comparison between the hypertrophy group and the L-Thy + berberine group showed that berberine 30 mg/(kg.d) x 10 d prevented the ventricular hypertrophy induced by L-Thy and decreased the cardiac indexes and CaN activity (P < 0.01); berberine elevated the cardiac NO content, Na(+)-K(+)-ATPase activity and Ca(2+)-ATPase activity (P < 0.01). CONCLUSION: Berberine can prevent the cardiac hypertrophy induced by L-thyroxine in rats.

Animals↗
PubMed2004

Cardiopulmonary bypass for thoracic aortic aneurysm: a report on 488 cases.

Our objective was to investigate different cardiopulmonary bypass (CPB) techniques for thoracic aortic aneurysm retrospectively. Four hundred and eighty-eight patients with thoracic aortic aneurysm received surgical treatment. Total CPB was used routinely in 331 cases with ascending aortic aneurysm. When the aneurysm expanded to the aortic arch, brain protection was executed by adopting deep hypothermia circulatory arrest (DHCA) or DHCA combined with retrograde cerebral perfusion (RCP). Selected cerebral perfusion via carotid artery was used in three cases and separated upper and lower body perfusion in five cases. Left heart bypass was adopted for the surgeries of 157 cases with descending aortic aneurysm. In two of the cases, ventricular defibrillation could not be achieved, and then bypass was altered to separated upper and lower body perfusion to acquire satisfactory outcome. In the ascending aortic aneurysm group, DHCA time in the 17 patients was 10-63 minutes (mean 35.58 +/- 18.81 min), and DHCA +/- RCP time in 61 patients was 16-81 minutes (mean 43.43 +/- 17.91 min). Total mortality of aortic aneurysm surgery requiring full CPB was 5.4% (18/331), in which eight patients died in emergency operations. The total mortality of emergency operation was 11.9% (8/67). In the descending aortic aneurysm group, time of left heart bypass was 125.56 +/- 57.28 min, and the total mortality was 7% (11 of 157 patients). Three patients developed postoperative paraplegia. Techniques for extracorporeal circulation for surgery of the aorta are dependent on the nature of the disease and require a flexible approach to meet the specific anatomical challenge. The ability to alter the perfusion circuit to meet unexpected situations should be anticipated and planned for. In this series, we have varied our approach to perfusion techniques as required with acceptable outcome data as compared to the international literature.

Adult↗