Biomedical subjects

Yan Kang

Publications and source records attributed to Yan Kang.

10 recordsLinked to original sources

PubMed2006

Neural stem cells: isolation and differentiation into cholinergic neurons.

This investigation aimed to isolate neural stem cells from neonatal hippocampus and induce them to differentiate into cholinergic neurons. The isolated neural stem cells were incubated in serum-free Dulbecco's modified Eagle medium/F12 medium added with 20 ng/ml basic fibroblast growth factor and B27. The cell line isolated from the hippocampal formation of neonatal rats expressed nestin and had the potency to form clones and differentiate into neurons, astrocytes and oligodendrocytes. Embryonic chick skeletal muscle extract was used to induce the differentiation of the neural stem cells into cholinergic neurons. Immunocytochemistry was used to detect the choline acetyltransferase antigen of cholinergic neurons for confirmation. The results showed that embryonic chick skeletal muscle extract could induce isolated neural stem cell to differentiate into a significantly larger number of cholinergic neurons than controls.

Animals↗

PubMed2005

An anatomic coordinate system of the femoral neck for highly reproducible BMD measurements using 3D QCT.

In this paper, a procedure for the determination of an anatomically oriented coordinate system of the femoral neck (NCS) in 3D spiral CT datasets is described. The origin of the NCS is centered in the minimal cross-sectional area of the neck. Its three axes are defined as follows: the so called neck axis is perpendicular to this area and points towards the femoral head, the second axis is the principal axis of the minimal cross-sectional area and the third axis is perpendicular to the other two. After a semi-automatic 3D segmentation of the proximal femur the NCS is automatically determined in a two-step minimization procedure. Relative to the coordinate system volumes of interest (VOIs) are positioned in which bone mineral density (BMD) and cortical thickness are analyzed. We investigated intra- and inter-operator precision of the position of the NCS, the BMD in cortical and trabecular VOIs, and cortical thickness in nine pelvic CT datasets obtained from clinical routine examinations. We further investigated the effect of increased noise by adding Gaussian distributed noise to measured projections before tomographic reconstruction. The mean precision error (averaged form the results of the nine datasets) of the NCS position was less than 0.5 mm and smaller than 2.25 degrees . There were no significant differences between inter- and intra-operator analyses. Precision errors in trabecular BMD were smaller than 3% in a stack of five 1 mm thin slices cut perpendicularly to the neck axis and smaller than 1% in a spherical VOI encompassing the neck. Relative precision errors for cortical BMD were smaller than 3% for both VOIs. An increase of noise up to a factor of 5 caused a maximal displacement of the NCS origin position by less than 1mm and a rotation by less than 2 degrees .

Bone Density↗

PubMed2005

Effects of acupuncture on the expression of glial cell line-derived neurotrophic factor (GDNF) and basic fibroblast growth factor (FGF-2/bFGF) in the left sixth lumbar dorsal root ganglion following removal of adjacent dorsal root ganglia.

This investigation studied the temporal changes in the expression of GDNF and FGF-2 in the left sixth lumbar (L6) dorsal root ganglion (DRG) after acupuncture in adult cats subjected to unilateral removal of adjacent DRG. The cats were divided into three groups. Group I were normal control animals. Group II cats were subjected to removal of DRG associated with the left L1-L5 and L7-S2 spinal nerves, sparing the L6 DRG. Group III cats received similar treatment as Group II ones, but in addition were subjected to acupuncture on the left side at acupuncture points (xuewei) the day after the operation. Both Groups II and III animals were perfused under anesthesia at 7 and 14 days post-operation (dpo) and their left DRG were processed for the immunohistochemical demonstration of GDNF and FGF-2. Following removal of adjacent DRG, the average number of all GDNF stained neurons in L6 DRG was decreased at 7 dpo and more so at 14 dpo. Acupuncture reversed this trend, as demonstrated in the increased average number of immunopositive small-to-medium sized neurons. FGF-2 expression was also less marked at 7 dpo but returned to normal at 14 dpo. Acupuncture significantly increased the average number of FGF-2 positive neurons compared with that in operated animals. This increase was observed in both large and small-to-medium sized neurons. In conclusion, our results demonstrated that the average number of GDNF and FGF-2 neurons in L6 DRG was decreased after unilateral removal of adjacent DRG but acupuncture could reverse some of the changes.

Acupuncture Therapy↗

PubMed2005

Design and application of an assessment protocol for electromagnetic tracking systems.

This paper defines a simple protocol for competitive and quantified evaluation of electromagnetic tracking systems such as the NDI Aurora (A) and Ascension microBIRD with dipole transmitter (B). It establishes new methods and a new phantom design which assesses the reproducibility and allows comparability with different tracking systems in a consistent environment. A machined base plate was designed and manufactured in which a 50 mm grid of holes was precisely drilled for position measurements. In the center a circle of 32 equispaced holes enables the accurate measurement of rotation. The sensors can be clamped in a small mount which fits into pairs of grid holes on the base plate. Relative positional/orientational errors are found by subtracting the known distances/ rotations between the machined locations from the differences of the mean observed positions/ rotation. To measure the influence of metallic objects we inserted rods made of steel (SST 303, SST 416), aluminum, and bronze into the sensitive volume between sensor and emitter. We calculated the fiducial registration error and fiducial location error with a standard stylus calibration for both tracking systems and assessed two different methods of stylus calibration. The positional jitter amounted to 0.14 mm(A) and 0.08 mm(B). A relative positional error of 0.96 mm +/- 0.68 mm, range -0.06 mm; 2.23 mm(A) and 1.14 mm +/- 0.78 mm, range -3.72 mm; 1.57 mm(B) for a given distance of 50 mm was found. The relative rotation error was found to be 0.51 degrees (A)/0.04 degrees (B). The most relevant distortion caused by metallic objects results from SST 416. The maximum error 4.2 mm(A)/ > or = 100 mm(B) occurs when the rod is close to the sensor(20 mm). While (B) is more sensitive with respect to metallic objects, (A) is less accurate concerning orientation measurements. (B) showed a systematic error when distances are calculated.

Biomechanical Phenomena↗

PubMed2005

[Primary study on the influence of blood transfusion on the STR genotypes of recipient's blood].

OBJECTIVE: To investigate whether any change occurred in recipients' blood collected at different times after transfusion with different quantity of blood. METHODS: Three patients were transfused with 400 ml, 800 ml and 1200 ml blood separately. The blood samples were collected from the recipients before transfusion and at 4 h, 8 h, 12 h after transfusion, and from the donors. DNA were extracted by Chelex-100 method and were amplified by the polymerase chain reaction (PCR). Six loci of D1S549, D18S865, D3S1754, D12S391, D12S375, D6S477 were selected. The PCR products were analyzed by polyacrylamide gel (PAG) vertical electrophoresis and silver staining. RESULTS: The investigations on the six STR loci revealed that the patients' STR genotypes remained unchanged within 12 h after blood transfusion. CONCLUSION: The STR genotypes of the donors would have no influence on the STR genotypes of the patients within 12 h after transfusion providing the volume of blood transfused is less than 1200 ml.

Asian People↗

PubMed2005

[Effect of partial dorsal root rhizotomy on expression of GDNF and FGF-2 in spared dorsal root ganglia].

OBJECTIVE: To explore the temporal change on the expression of GDNF and FGF-2 in spared dorsal root ganglia after partial dorsal root rhizotomy. METHODS: Fifteen cats were divided into the normal group, and the partial dorsal root rhizotomy groups. The partial dorsal root rhizotomy groups were sacrificed on day 7 or 14 and the L6 dorsal root ganglia were taken out from each animal and were made into frozen sections 20 microm in thickness respectively. The sections were stained under the same condition using specific GDNF (1 : 500) and FGF-2 (1 : 500) antibody by ABC method. The GDNF and FGF-2 positive large-sized, and medium-small-sized neurons in DRG were counted in each group. All data were analyzed by q test. RESULTS: GDNF immunoreactivity was observed in both large-sized and medium-small-sized DRG neurons. The number of total positive neurons decreased 7 days after partial dorsal root rhizotomy, and was still small after 14 days. Interestingly, the tendency in the number of positive medium-small-sized DRG neurons was just the same as that of total positive neurons while the positive large sized neurons displayed no difference between the 7th day group and the 14th day group, though the number also decreased after operation. FGF-2 immunoreactivity was noted in both large sized and medium-small-sized DRG neurons. After partial dorsal root rhizotomy, the number of total positive neurons decreased on the 7th day and came back to normal level on the 14th day. The number of positive medium-small sized neurons also showed declination followed by escalation, just the same as that of total positive neurons while the number of positive large-sized neurons exhibited no difference between the normal group and the rhizotomy groups. CONCLUSION: Partial dorsal root rhizotomy can lead to continuously declination of total GDNF immunoreactive neurons in spared ganglia, till the 14th day. FGF-2 expression showed declination on the 7th day, but returned to normal level on the 14th day after partial dorsal root rhizotomy. These findings indicate that the expression change of GDNF and FGF-2 after partial dorsal root rhizotomy correlates with the plasticity of spinal cord.

Animals↗

PubMed2004

Interactive 3D editing tools for image segmentation.

Segmentation is an important part of image processing, which often has a large impact on quantitative image analysis results. Fully automated operator independent segmentation procedures that successfully work in a population with a larger biological variation are extremely difficult to design and usually some kind of operator intervention is required, at least in pathological cases. We developed a variety of 3D editing tools that can be used to correct or improve results of initial automatic segmentation procedures. Specifically we will discuss and show examples for three types of editing tools that we termed: hole-filling (tool 1), point-bridging (tool 2), and surface-dragging (tool 3). Each tool comes in a number of flavors, all of which are implemented in a truly 3D manner. We describe the principles, evaluate efficiency and flexibility, and discuss advantages and disadvantages of each tool. We further demonstrate the superiority of the 3D approach over the time-consuming slice-by-slice editing of 3D datasets, which is still widely used in medical image processing today. We conclude that performance criteria for automatic segmentation algorithms may be eased significantly by including 3D editing tools early in the design process.

Algorithms↗

PubMed2003

A new accurate and precise 3-D segmentation method for skeletal structures in volumetric CT data.

We developed a highly automated three-dimensionally based method for the segmentation of bone in volumetric computed tomography (CT) datasets. The multistep approach starts with three-dimensional (3-D) region-growing using local adaptive thresholds followed by procedures to correct for remaining boundary discontinuities and a subsequent anatomically oriented boundary adjustment using local values of cortical bone density. We describe the details of our approach and show applications in the proximal femur, the knee, and the skull. The accuracy of the determination of geometrical parameters was analyzed using CT scans of the semi-anthropomorphic European spine phantom. Depending on the settings of the segmentation parameters cortical thickness could be determined with an accuracy corresponding to the side length of 1 to 2.5 voxels. The impact of noise on the segmentation was investigated by artificially adding noise to the CT data. An increase in noise by factors of two and five changed cortical thickness corresponding to the side length of one voxel. Intraoperator and interoperator precision was analyzed by repeated analysis of nine pelvic CT scans. Precision errors were smaller than 1% for trabecular and total volumes and smaller than 2% for cortical thickness. Intraoperator and interoperator precision errors were not significantly different. Our segmentation approach shows: 1) high accuracy and precision and is 2) robust to noise, 3) insensitive to user-defined thresholds, 4) highly automated and fast, and 5) easy to initialize.

Algorithms↗

PubMed2002

[Therapeutic effect of high-density lipoprotein of human plasma on rat endotoxemia].

OBJECTIVE: To investigate the therapeutic effect of high-density lipoprotein (HDL) of human plasma on rat endotoxemia. METHODS: Rats were divided into 2 groups randomly, the treated group received bolus intravenous endotoxin (500 EU/kg), then followed by a bolus HDL (75 mg/kg) intravenously as their blood pressure decreased obviously. The control group just received bolus intravenously endotoxin (500 EU/kg) without HDL. Blood pressure, survival time, the concentration of TNF and the levels of endotoxin in plasma were determined using radioimmunoassay and limulus lysate test. RESULTS: The decrease of blood pressure was obviously attenuated (P < 0.01), the survival time was significantly increased (P < 0.01) and the concentration of plasma TNF was decreased (P < 0.05) in the treated group, compared with those in the control group. The levels of endotoxin were of no significant difference between the two groups (P > 0.05). CONCLUSION: HDL of human plasma has obvious therapeutic effect on rat endotoxemia it could enhance the resistance of rats to endotoxemia, and the mechanism therein may be related to the inhibition of the release of TNF.

Animals↗

PubMedDate not supplied

Optimization of polymerization conditions of furan with aniline for variable conducting polymers.

A high-throughput multiparameter optimization of chemical oxidative polymerization conditions has been developed for a facile synthesis of furan homopolymers and furan/aniline copolymers using a combinatorial method. The polymerization yield, molecular structure, and properties of the polymers would be optimized against typical polymerization parameters, including oxidant species, medium species, temperature, oxidant/monomer ratio, monomer concentration, dopant concentration, and furan/aniline comonomer ratio. The electrical conductivity, lead ion adsorptivity, chemical resistance, and thermal behavior of the polymers were also elaborated. It is found that only a combination of FeCl(3) and nitromethane as oxidant and medium, respectively, is appropriate for the furan homopolymerization. The homopolymerization yield increases consistently with an increase in the monomer concentration from 0.05 to 0.2 M and the FeCl(3)/furan molar ratio from 0.25 to 1.25. Although the as-prepared polyfuran exhibits very low conductivity, down to 10(-11) S cm(-1), the HCl- and HClO(4)-doped polyfurans possess much higher conductivities of 9.2 x 10(-8) and 2.38 x 10(-5) S cm(-1), respectively. In addition, the conductivity of the furan/aniline copolymer rises steadily with increasing aniline content, although the copolymerization yield shows a minimum at the furan/aniline molar ratio of 60/40, which is evidence of the occurrence of a real copolymerization between the furan and aniline monomers. The difficulty of synthesizing conducting polyfuran could be overcome to some extent by the polymerization in an appropriate condition optimized in this study. Particularly, the difficulty of synthesizing poly(furan-co-aniline) having much higher conductivity than the polyfuran would be largely conquered by chemical oxidative copolymerization of furan with aniline.

Aniline Compounds↗