Biomedical subjects

Tao Geng

Publications and source records attributed to Tao Geng.

12 recordsLinked to original sources

PubMed2006

Use of surface enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) to study protein expression in a rat model of cocaine withdrawal.

Surface enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) is an analytical technology for proteomic analysis that combines chromatography and mass spectrometry. At present, this technology is most commonly being exploited for the simultaneous measurement of numerous proteins in serum, but has also been utilized in organ tissue, although rarely in the brain. We applied SELDI-TOF MS technology to study protein expression in the brain of rats withdrawn from repeated cocaine exposure. Our goals were to optimize sample preparation and ProteinChip Array protocols for brain tissue, to verify the reproducibility of SELDI-TOF mass spectra and to determine whether SELDI-TOF MS detects differentially expressed proteins in cocaine- versus saline-treated rats. Consequently, we have developed an optimal protocol and generated a reproducible spectral pattern with six dominant peaks in all test samples. We have detected two smaller peaks (m/z: 5179, 5030) that were significantly increased (p < 0.05) in cocaine-treated rats compared to saline-treated rats. In summary, the application of SELDI-TOF MS to the study of protein expression in a rat model of cocaine withdrawal is feasible and has the potential to generate new hypotheses.

Animals↗

PubMed2006

Effects of GM-CSF on the stem cells mobilization and plasma C-reactive protein levels in patients with acute myocardial infarction.

BACKGROUND: Stem cell mobilization with granulocyte colony-stimulating factor (G-CSF) has been proposed to improve cardiac function and prevent ventricular remodeling after acute myocardial infarction (AMI) in preclinical and clinical studies. It has been demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) can improve collateral flow in patients with coronary artery disease. In this study, we used GM-CSF to mobilize the bone marrow stem cells (BMSCs) in patients with AMI and assessed the safety, feasibility and efficacy of this treatment. METHODS: Twenty patients with AMI were randomly divided into GM-CSF group (10 microg/kg body weight, for 7 days) and control group (saline). The absolute counts of CD34 positive cells in peripheral blood were enumerated with flow cytometry. Plasma levels of C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrotic factor-alpha (TNF-alpha) were measured on days 1, 3, 7, 10 and 14. Echocardiography (UCG) was done on day 7 and after 12 months. RESULTS: Peripheral CD34 positive cells in GM-CSF patients obviously increased shortly after using GM-CSF and peaked on day 7 (p<0.01 versus controls). GM-CSF group had significantly higher mean level of plasma CRP than controls on day 10 (p<0.05). The levels of IL-6 and TNF-alpha in therapy patients were as same as in controls. Left ventricular ejection fraction (EF) at 12 months was significantly greater than that on day 7 in GM-CSF patients (p<0.05). The EF in controls had no obvious differences in follow-up. There were no statistically differences regarding the left ventricular end-systolic volume (LVESV), the left ventricular end-diastolic volume (LVEDV) and the resting wall thickening (WT) in the infarct zone in two groups in follow-up. CONCLUSIONS: Our results demonstrate that GM-CSF can effectively mobilize the CD34 positive cells and at the same time may increase the levels of plasma CRP in patients with AMI. The remote effects of this drug need to be further defined.

Aged↗

PubMed2006

Infantile seizures and other epileptic phenotypes in a Chinese family with a missense mutation of KCNQ2.

INTRODUCTION: Benign familial infantile seizures (BFIS) is a form of idiopathic epilepsy characterized by clusters of afebrile seizures occurring around the sixth month of life and a favorable outcome. Linkage analysis has revealed that three chromosomal segments, 19q12-q13.1, 16p12-q12, and 2q23-31, are linked to this disorder. SUBJECTS AND METHODS: We report here a large Chinese family in which all 17 affected members had had infantile seizures with onset at age 2-4 months, with two of these also manifesting seizures later in life accompanied with either choreoathetosis or myokymia. Linkage analysis in this family confirmed a previous report of genetic heterogeneity in BFIS - since linkage was excluded at the above-mentioned known BFIS loci - and suggested a possible linkage to the KCNQ2 gene, which is believed to be a voltage gated potassium channel gene responsible for benign familial neonatal seizures (BFNS). RESULTS AND DISCUSSION: Sequencing of the KCNQ2 gene revealed that all 17 affected family members carried a heterozygous Gly-to-Val (G271V) mutation in the conserved pore region that resulted from a guanine-to-thymine transition in exon 5 of KCNQ2. The same mutation with a comparable localization in the KCNQ3 (G310V) gene has been found in BFNS patients. The same conserved amino acid was also found to be mutated in the KCNQ1 gene in a family with Long QT Syndrome.

Age of Onset↗

PubMed2006

A reflexive neural network for dynamic biped walking control.

Biped walking remains a difficult problem, and robot models can greatly facilitate our understanding of the underlying biomechanical principles as well as their neuronal control. The goal of this study is to specifically demonstrate that stable biped walking can be achieved by combining the physical properties of the walking robot with a small, reflex-based neuronal network governed mainly by local sensor signals. Building on earlier work (Taga, 1995; Cruse, Kindermann, Schumm, Dean, & Schmitz, 1998), this study shows that human-like gaits emerge without specific position or trajectory control and that the walker is able to compensate small disturbances through its own dynamical properties. The reflexive controller used here has the following characteristics, which are different from earlier approaches: (1) Control is mainly local. Hence, it uses only two signals (anterior extreme angle and ground contact), which operate at the interjoint level. All other signals operate only at single joints. (2) Neither position control nor trajectory tracking control is used. Instead, the approximate nature of the local reflexes on each joint allows the robot mechanics itself (e.g., its passive dynamics) to contribute substantially to the overall gait trajectory computation. (3) The motor control scheme used in the local reflexes of our robot is more straightforward and has more biological plausibility than that of other robots, because the outputs of the motor neurons in our reflexive controller are directly driving the motors of the joints rather than working as references for position or velocity control. As a consequence, the neural controller and the robot mechanics are closely coupled as a neuromechanical system, and this study emphasizes that dynamically stable biped walking gaits emerge from the coupling between neural computation and physical computation. This is demonstrated by different walking experiments using a real robot as well as by a Poincaré map analysis applied on a model of the robot in order to assess its stability.

Algorithms↗

PubMed2006

Selective enrichment media affect the antibody-based detection of stress-exposed Listeria monocytogenes due to differential expression of antibody-reactive antigens identified by protein sequencing.

Selective enrichment broths are frequently used to recover stressed Listeria cells to detectable levels, but the ability of antibodies to detect these cells from various commonly used enrichment media is unknown. In this study, a polyclonal (PAb) and monoclonal (MAb) antibody were used to examine the variation in antigen expression on healthy or stress-recovered Listeria monocytogenes cells grown in brain heart infusion broth, buffered Listeria enrichment broth (BLEB), Listeria repair broth (LRB), University of Vermont medium (UVM), and Fraser broth (FB) for immunodetection. Indirect enzyme-linked immunosorbent assay (ELISA) data showed that L. monocytogenes subjected to stresses (acid, cold, heat, and salt) and then grown in BLEB gave the highest reaction with the anti-Listeria PAb while those grown in LRB gave the highest reaction with the MAb C11E9. Cells grown in UVM and FB gave poor ELISA values with both antibodies. Western blotting with PAb revealed differential expression of surface proteins of 62, 58, 50, 43, and 30 kDa on L. monocytogenes cells, with most proteins displaying elevated expression in BLEB and LRB but reduced or no expression in UVM or FB. Similar differential expressions were noticed for C11E9. PAb-reactive proteins were identified as putative LPXTG-motif cell-wall anchor-domain protein (62 kDa; lmo0610), flavocytochrome C fumarate reductase chain A homolog protein (58 kDa; lmo0355), enolase (50 kDa; lmo2455), glyceraldehyde 3-phosphate dehydrogenase (43 kDa; lmo2459), and hypothetical phospho-sugar binding protein (30 kDa; lmo0041), respectively, and the MAb-reactive 66-kDa protein was confirmed to be N-acetylmuramidase (lmo2691). In conclusion, BLEB and LRB favorably supported increased expression of antigens and proved to be superior to UVM and FB for immunodetection of stressed L. monocytogenes cells.

Antibodies, Monoclonal↗

PubMed2006

[Correlation of changes in circulating bone marrow stem cells in pregnant rabbits after acute myocardial infarction with serum estradiol].

OBJECTIVE: To investigate the changes in circulating bone marrow stem cells in pregnant rabbits after AMI (AMI) and their relationship with estradiol. METHODS: Three groups of rabbits were used, namely pregnancy and AMI group, AMI group without pregnancy, and sham operation group with pregnancy. The ratio of CD90(+) cells in the peripheral blood was determined with flow cytometry in all the rabbits, and serum estradiol level measured. Four weeks after AMI, hemodynamic measurements were carried out. The morphological changes of the myocardial tissues were examined with ImageJ 1.31. RESULTS AND CONCLUSION: Four weeks after AMI, the two pregnancy groups showed a higher Left ventricular end systolic pressure(LVESP) and+dp/dtmax, lower left ventricular end-diastolic pressure (LVEDP) and -dp/dtmax and high levels of CD90(+) cells in peripheral blood than AMI group without pregnancy (P<0.01). The ratio of circulating CD90(+) cells increased gradually with gestational age and peaked at the end stage of pregnancy. After delivery the circulating CD90+ cell ratio decreased sharply, showing a significant correlation with serum estradiol level (r=0.725, P<0.01). Four weeks after AMI, the pregnancy group had smaller myocardial infarction (MI) volume than the non-pregnant group (22.17+/-6.34% vs 38.86+/-5.97%, P<0.05). Circulating bone marrow stem cells increased during pregnancy with gestational age and peaked at the end stage of pregnancy. Ten days after delivery, the stem cells resumed basically the normal level. The proportion of circulating bone marrow stem cells was significantly correlated with the level of serum estradiol during pregnancy, and mobilization of the bone marrow stem cells induced by acute ischemic event in pregnant rabbits was advanced. 4 weeks after AMI, the pregnant rabbits showed better heart contraction and diastolic function than the non-pregnant ones.

Animals↗

PubMed2006

The expression of maxiK channel alpha--subunit during human macrophages differentiating into foam cells.

OBJECTIVE: To investigate the expression of MaxiK channel alpha-subunit during human monocyte-derived macrophages differentiating into foam cells. METHODS: Human peripheral blood monocytes were isolated from male healthy volunteers by density gradient centrifugation, which, by culture, differentiated further into macrophages as a homogeneous monocyte population. The foam cell model originated from human macrophage was established by incubating macrophages with oxidized low density lipoprotein (OxLDL). The expression of MaxiK channel alpha-subunit was investigated by RT-PCR techniques, Western blotting and immunocytochemistry. RESULTS: After incubating macrophages with 30 mg/L OxLDL for 60 hours, the cellular contents of total cholesterol (TC), free cholesterol (FC) and cholesterol ester (CE) were markedly increased and the ratio of CE/TC was further raised from (14.437 +/- 6.781) % to (57.946 +/- 3.507) %. Although the expression of MaxiK channel alpha-subunit was downregulated during human monocyte-derived macrophages differentiating into foam cells, there was no significant difference between macrophages and foam cells (P > 0.05). CONCLUSION: That 30 mg/L OxLDL can lead the monocyte-derived macrophage cultured for 60 hours to differentiate into foam cell, but the expression of MaxiK channel alpha-subunit does not change obviously.

Adult↗

PubMed2006

[Dynamic changes of plasma VEGF, SDF-1 and peripheral CD34+ cells in patients with acute myocardial infarction].

OBJECTIVE: To investigate the changes in plasma levels of vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1 (SDF-1) and in peripheral CD34(+) cells in patients with acute myocardial infarction (AMI), and explore their role in AMI. METHODS: Enzyme-linked immunoassay (ELISA) was employed for measuring the levels of VEGF and SDF-1 in AMI patients on days 1, 3, 7, 10, and 14 of onset and in normal control subjects. The absolute counts of CD34(+) in the peripheral blood were measured on days 1, 7, and 14 by flow cytometry in AMI patients, with their myocardial enzyme and troponin I detected and electrocardiography (ECG) and echocardiography (UCG) recorded. RESULTS: Peripheral CD34(+) cells obviously increased on day 7 after AMI onset (2.35-/+0.72/microl vs 1.48-/+0.49/micro, P<0.05). VEGF levels were significantly higher in AMI patients than in the control subjects, reaching the peak level and on day 14 (197.56-/+39.87 vs 53.79-/+18.12 pg/ml, P<0.01). SDF-1 level obviously decreased on day 1 after AMI onset (1683.12-/+224.79 vs 2178.67-/+265.34 pg/ml, P<0.01), followed by gradually increased to the control level. Obvious correlation was noted between the level of VEGF on day 7 and the peak level of peripheral CD34(+) cells, and the peak plasma VEGF level was obviously associated with the peak serum CK-MB and troponin I levels. CONCLUSION: The stem cells are mobilized into the peripheral blood in the event of AMI. Obviously increased VEGF level following AMI may persist for at least 2 weeks, whereas SDF-1 level undergoes temporary decrement after AMI. The dynamic changes of VEGF and SDF-1 can be related to the mobilization and homing of the stem cells to the injured myocardium.

Adult↗

PubMed2005

Mechanistic study of membrane concentration and recovery of Listeria monocytogenes.

Detection of the foodborne pathogen Listeria monocytogenes requires that food samples be processed to remove proteins and lipids, concentrate microorganisms to a detectable concentration, and recover the concentrated cells in a small volume compatible with micron-scale biochips. Mechanistic considerations addressed in this research include the roles of membrane structure, pore size, and detergents in maximizing recovery of cells from a complex biological fluid. The fluid in this case was a food sample (hotdog extract) inoculated with L. monocytogenes. This study showed how membrane filtration using a syringe filter is able to concentrate L. monocytogenes by 95x with up to 95% recovery of living microorganisms by concentrating 50 mL of food sample into a volume of 500 microL. Tween 20 was added to the sample to prevent irreversible adsorption of the microorganism to the membrane and thereby help to ensure high recovery. Comparison of polycarbonate, mixed cellulose, nylon, and PVDF membranes with 0.2 to 0.45 microm pores showed the 0.2 microm polycarbonate membrane with straight through, mono-radial pores gives the highest recovery of living microorganisms. The mixed cellulose, nylon, and PVDF membranes have a fibrous structure whose characteristic openings are much larger than their effective pore size cut-offs of 0.22 or 0.45 microm. We define conditions for rapid membrane-based cell concentration and recovery that has the potential to supplant enrichment steps that require a day or more. This approach has the added benefit of facilitating examination of a large amount of fluid volume by reducing its volume to a range that is compatible with the microliter scales of biochip or other biosensor detection systems.

Filtration↗

PubMed2004

Detection of low levels of Listeria monocytogenes cells by using a fiber-optic immunosensor.

Biosensor technology has a great potential to meet the need for sensitive and nearly real-time microbial detection from foods. An antibody-based fiber-optic biosensor to detect low levels of Listeria monocytogenes cells following an enrichment step was developed. The principle of the sensor is a sandwich immunoassay where a rabbit polyclonal antibody was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction to capture Listeria cells on the fiber. Capture of cells on the fibers was confirmed by scanning electron microscopy. A cyanine 5-labeled murine monoclonal antibody, C11E9, was used to generate a specific fluorescent signal, which was acquired by launching a 635-nm laser light from an Analyte 2000 and collected by a photodetector at 670 to 710 nm. This immunosensor was specific for L. monocytogenes and showed a significantly higher signal strength than for other Listeria species or other microorganisms, including Escherichia coli, Enterococcus faecalis, Salmonella enterica, Lactobacillus plantarum, Carnobacterium gallinarum, Hafnia alvei, Corynebacterium glutamicum, Enterobacter aerogenes, Pseudomonas aeruginosa, and Serratia marcescens, in pure or in mixed-culture setup. Fiber-optic results could be obtained within 2.5 h of sampling. The sensitivity threshold was about 4.3 x 10(3) CFU/ml for a pure culture of L. monocytogenes grown at 37 degrees C. When L. monocytogenes was mixed with lactic acid bacteria or grown at 10 degrees C with 3.5% NaCl, the detection threshold was 4.1 x 10(4) or 2.8 x 10(7) CFU/ml, respectively. In less than 24 h, this method could detect L. monocytogenes in hot dog or bologna naturally contaminated or artificially inoculated with 10 to 1,000 CFU/g after enrichment in buffered Listeria enrichment broth.

Animals↗

PubMed2003

Micro-assembly of functionalized particulate monolayer on C18-derivatized SiO2 surfaces.

This work describes a simple approach to immobilize functionalized colloidal microstructures onto a C(18)-coated SiO(2) substrate via specific or non-specific bio-mediated interactions. Biotinylated bovine serum albumin pre-adsorbed onto a C(18) surface was used to mediate the surface assembly of streptavidin-coated microbeads (2.8 microm), while a bare C(18) surface was used to immobilize anti-Listeria antibody-coated microbeads (2.8 microm) through hydrophobic interactions. For a C(18) surface pre-adsorbed with bovine serum albumin, hydrophobic polystyrene microbeads (0.8 microm) and positively charged dimethylamino microbeads (0.8 microm) were allowed to self-assemble onto the surface. A monolayer with high surface coverage was observed for both polystyrene and dimethylamino microbeads. The adsorption characteristics of Escherichia coli and Listeria monocytogenes on these microbead-based surfaces were studied using fluorescence microscopy. Both streptavidin microbeads pre-adsorbed with biotinylated anti-Listeria antibody and anti-Listeria antibody-coated microbeads showed specific capture of L. monocytogenes, while polystyrene and dimethylamino microbeads captured both E. coli and L. monocytogenes non-specifically. The preparation of microbead-based surfaces for the construction of microfluidic devices for separation, detection, or analysis of specific biological species is discussed.

Adsorption↗

PubMed2003

Composite surface for blocking bacterial adsorption on protein biochips.

The design and fabrication of protein biochips requires characterization of blocking agents that minimize nonspecific binding of proteins or organisms. Nonspecific adsorption of Escherichia coli, Listeria innocua, and Listeria monocytogenes is prevented by bovine serum albumin (BSA) or biotinylated BSA adsorbed on SiO(2) surfaces of a biochip that had been modified with a C(18) coating. Biotinylated BSA forms a protein-based surface that in turn binds streptavidin. Because streptavidin has multiple binding sites for biotin, it in turn anchors other biotinylated proteins, including antibodies. Hence, biotinylated BSA simultaneously serves as a blocking agent and a foundation for binding an interfacing protein, avidin or streptavidin, which in turns anchors biotinylated antibody. In our case, the antibody is C11E9, an IgG-type antibody that binds Listeria spp. Nonspecific adsorption of another bacterium, Escherichia coli, is also minimized due to the blocking action of the BSA. The blocking characteristics of BSA adsorbed on C(18)-derivatized SiO(2) surfaces for construction of a protein biochip for electronic detection of pathogenic organisms is investigated.

Adsorption↗