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Y Ding

Publications and source records attributed to Y Ding.

At least 37 records · Page 2Linked to original sources
PubMed2005

Double-antigen sandwich ELISA for detection of antibodies to SARS-associated coronavirus in human serum.

The study presented here was conducted to evaluate the performance of a double-antigen sandwich ELISA to detect antibodies in human serum against the coronavirus associated with severe acute respiratory syndrome (SARS). A recombinant partial nucleocapsid protein of SARS-associated coronavirus was used as a serodiagnostic antigen in the ELISA. A total of 2892 clinical serum samples were tested with the ELISA kit, which positively identified 25 of 35 (71.4%) samples of patients with confirmed SARS infection, 286 of 407 (70%) samples of patients suspected of having SARS, 229 of 302 (75.8%) samples of convalescent SARS patients, and 0 of 544 samples obtained from healthcare workers; only 1 of 1604 clinical samples obtained from patients with other diseases demonstrated a weakly positive result. These results indicate that the double-antigen sandwich ELISA is an effective screening method for the serodiagnosis of SARS-associated coronavirus.

Antibodies, Viral↗
PubMed2005

Epigenetic changes in the repression and induction of asparagine synthetase in human leukemic cell lines.

In common with certain other lymphoid neoplasms, cells of the human lymphocytic leukemia lines 1873 and 1929 are asparagine (ASN) auxotrophs. Asparagine synthetase (ASY), which is a housekeeping gene, is repressed and the promoting region of the gene is highly methylated. We now demonstrate in these cells multiple levels in control of the expression of this gene, in a system of cocultivation with macrophages and other cell types. In this system, mediated by cell-to-cell contact, ASY becomes expressed by the leukemic cells and they become prototrophic. Demethylation of ASY occurs; it follows expression and is permanent over multiple cell generations, but the cells return to auxotrophy with rapid repression of ASY on removal from cell contact. With ASY expression, the associated histone H3 at lysine position 9 (H3K9) becomes acetylated and H3K4, methylated. In contrast to other systems, H3K9 methylation does not characterize the repressed state. The changes leading from repression to induction of ASY and demethylation parallel the physiological changes specific to functional maturation of normal lymphoid precursors. The lability of expression of ASY has potential significance in determining the sensitivity of leukemic cells to L-asparaginase.

Acetylation↗
PubMed2005

Isolation and identification of nitrogen-fixing bacilli from plant rhizospheres in Beijing region.

AIMS: To isolate and identify nitrogen-fixing bacilli from the plant rhizospheres in Beijing region of China. METHODS AND RESULTS: A total of 29 isolates were selectively obtained from the rhizospheres of wheat, maize, ryegrass and willow based on their growth on nitrogen-free medium and their resistance to 100 degrees C for 10 min. Of the 29 isolates, seven had nifH gene determined by PCR amplification. The seven isolates were found to belong to the genera Bacillus and Paenibacillus based on phenotypic characterization, 16S rDNA sequence, G+C content and DNA-DNA hybridization. Isolates T1 and W5 were identified as Bacillus cereus and Bacillus marisflavi respectively. Isolates G1, C4 and C5 were identified as Bacillus megaterium. Isolate G2 was identified as Paenibacillus polymyxa and isolate T7 as Paenibacillus massiliensis. CONCLUSIONS: This study suggests that nifH gene could be detected in the both genera Bacillus and Paenibacillus. These degenerate primers for nifH gene fragment used in this study were shown to be useful for identifying nitrogen-fixing bacilli. SIGNIFICANCE AND IMPACT OF THE STUDY: It is the first demonstration that nitrogen fixation exists in B. marisflavi and P. massiliensis and the first report of the sequences of the nifH gene from B. megaterium and B. cereus. The nitrogen-fixing bacilli obtained in this study will be used in our future research for investigating the mechanisms of nitrogen fixation in bacilli.

Bacillus↗
PubMed2005

The establishment of the photo management system for orthodontics and its clinical application.

It is necessary for orthodontists to collect and analyze the patients' photographic data. By conventional methods, these photo data were commonly saved on film, which were frail and often resulted in data loss. Furthermore, it is not convenient for the orthodontists to consult and study these data during clinical research. A critical problem thus arises in managing these photo data scientifically. The computer technique and picture processing method were employed in the present study to establish the Photo Management System for Orthodontics (PMSO), which makes the administration of patients' photo data more scientific, convenient, and effective than before. This system is characterized as follows: (1) Clinical orthodontists designed and programmed the system, which is "close to clinical reality and serves the clinic". Orthodontists can easily use it without any training course. (2) The images can be imported from many devices, such as digital cameras, scanners, and electronic data storage media such as floppy disks. (3) Even two groups of photos (four images) could be displayed in the same window for comparison and study. This function allows orthodontists to easily observe the differences in the same patient's photos at different stages, which is important to obtain comprehensive knowledge of the patient. (4) The network technique makes it possible for the photos to be shared. The orthodontists can get the patients' photos through the network without going to the radiology department or the imaging room. (5) It is helpful for orthodontic research since the photos can be exported easily in different ways. (6) This is shared software; orthodontists can use it for free.

Computer Communication Networks↗
PubMed2004

Using complexity measure factor to predict protein subcellular location.

Recent advances in large-scale genome sequencing have led to the rapid accumulation of amino acid sequences of proteins whose functions are unknown. Because the functions of these proteins are closely correlated with their subcellular localizations, it is vitally important to develop an automated method as a high-throughput tool to timely identify their subcellular location. Based on the concept of the pseudo amino acid composition by which a considerable amount of sequence-order effects can be incorporated into a set of discrete numbers (Chou, K. C., Proteins: Structure, Function, and Genetics, 2001, 43: 246-255), the complexity measure approach is introduced. The advantage by incorporating the complexity measure factor as one of the pseudo amino acid components for a protein is that it can more effectively reflect its overall sequence-order feature than the conventional correlation factors. With such a formulation frame to represent the samples of protein sequences, the covariant-discriminant predictor (Chou, K. C. and Elrod, D. W., Protein Engineering, 1999, 12: 107-118) was adopted to conduct prediction. High success rates were obtained by both the jackknife cross-validation test and independent dataset test, suggesting that introduction of the concept of the complexity measure into prediction of protein subcellular location is quite promising, and might also hold a great potential as a useful vehicle for the other areas of molecular biology.

Algorithms↗
PubMed2004

Doubly resonant single-layer bandpass optical filters.

A bandpass filter based on guided-mode resonance effects in a single-layer periodic waveguide is presented. Strong refractive-index modulation is used to support the excitation of a resonance pair in which leaky waveguide mode TE0 is excited by the second diffraction order and TE2 by the first diffraction order. It is shown that one resonance provides a broad low-transmission band, whereas the other supplies the transmission peak through its asymmetrical line shape. A bandpass filter with central wavelength at 1.55 microm is presented to demonstrate this concept.

Journal Article↗
PubMed2004

Methylation of the asparagine synthetase promoter in human leukemic cell lines is associated with a specific methyl binding protein.

We have examined the methylation profiles of the asparagine synthetase (ASY) promoter in a number of human leukemic cell lines in relation to their asparagine (ASN) requirements in vitro. Cells in which the promoter is highly methylated are auxotrophs and express ASY at very low levels. Electromobility shift assays (EMSA) of nuclear extracts with oligomers from the promoting region show, in addition to recognized transcription factor binding, a novel methyl binding protein specific for a 12 base consensus sequence, which includes a single methylated CpG. This sequence overlaps that of the amino-acid response unit of the ASY promoter, which is activated byATF4 and C/EBP. Competition by the methyl binding protein could account for the observed failure of the methylated promoter to bind these transcription factors and consequently, although other mechanisms can also be operative, for the specific repression of the gene. The ASY methyl binding protein (ASMB) is present in leukemic lymphoid and myeloid cells irrespective of their methylation status, and in normal lymphocytes after phytohemagglutinin stimulation. It has been purified by affinity chromatography and has a molecular size of 40 kDa in 10% SDS-polyacrylamide gels.

Aspartate-Ammonia Ligase↗
PubMed2004

Energy-based analysis of milling alpha-lactose monohydrate.

Some observations on the milling of alpha-lactose monohydrate with a Retsch single-ball mill are reported. The effects of mill loading and frequency of the mill motion were investigated. At a given frequency, a lower mill loading showed a higher milling efficiency. For a given mill loading, size reduction rate increased exponentially with frequency. The milling behavior was analyzed with three energy-based models; namely, Rittinger's, Kick's, and Bond's models. The results suggest that Rittinger's model best describes the milling behavior for low mill loadings at high frequencies, whereas the data for high loading milling at low frequencies fit Kick's model better. The results also indicate that attrition and/or chipping is the dominant mechanism for milling at low frequencies with high loadings because of the shear action of the milling ball rolling on the powder bed. Also, as a result of impact of the milling ball on the two ends of the milling jar, fragmentation is responsible for size reduction at high frequencies with low loadings.

Algorithms↗
PubMed2004

Motor balance and coordination training enhances functional outcome in rat with transient middle cerebral artery occlusion.

The goal of this study was to determine if relatively complex motor training on Rota-rod involving balance and coordination plays an essential role in improving motor function in ischemic rats, as compared with simple locomotor exercise on treadmill. Adult male Sprague-Dawley rats with (n=40) or without (n=40) ischemia were trained under each of three conditions: (1) motor balance and coordination training on Rota-rod; (2) simple exercise on treadmill; and (3) non-trained controls. Motor function was evaluated by a series of tests (foot fault placing, parallel bar crossing, rope and ladder climbing) before and at 14 or 28 days after training procedures in both ischemic and normal animals. Infarct volume in ischemic animals was determined with Nissl staining. Compared with both treadmill exercised and non-trained animals, Rota-rod-trained animals with or without ischemia significantly (P<0.01) improved motor performance of all tasks except for foot fault placing after 14 days of training, with normal rats having better performance. Animals trained for up to 28 days on the treadmill did not show significantly improved function. With regard to foot fault placing task, performance on foot placing was improved in ischemic rats across the three measurements at 0, 14 and 28 days regardless of training condition, while the normal group reached their best performance at the beginning of measurement. No significant differences in infarct volume were found in rats trained either with Rota-rod (47+/-4%; mean+/-S.E.), treadmill (45+/-5%) or non-exercised control (45+/-3%). In addition, no obvious difference could be detected in the location of the damage which included the dorso-lateral portion of the neostriatum and the frontoparietal cortex, the main regions supplied by the middle cerebral artery. The data suggest that complex motor training rather than simple exercise effectively improves functional outcome.

Animals↗
PubMed2004

Exercise pre-conditioning reduces brain damage in ischemic rats that may be associated with regional angiogenesis and cellular overexpression of neurotrophin.

There is increasing evidence that physical activity is associated with a decreased stroke risk. The purpose of this study was to determine if exercise could also reduce brain damage in rats subjected to transient middle cerebral artery (MCA) occlusion, and if the reduced brain injury is associated with angiogenesis as well as cellular expression of the nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in regions supplied by the MCA. Adult male Sprague Dawley rats (n=36) exercised 30 min each day for 3 weeks on a treadmill on which repetitive locomotor movement was required. Then, stroke was induced by a 2-h MCA occlusion using an intraluminal filament, followed by 48 h of reperfusion. In addition to the two exercised groups of animals with or without MCA occlusion, there were two other groups of animals, with or without MCA occlusion, housed for the same duration and used as non-exercised controls. Brain damage in ischemic rats was evaluated by neurologic deficits and infarct volume. Exercise preconditioned and non-exercised brains were processed for immunocytochemistry to quantify the number of microvessels or NGF- and BDNF-labeled cells. Pre-ischemic motor activity significantly (P<0.01) reduced neurologic deficits and infarct volume in the frontoparietal cortex and dorsolateral striatum. Cellular expressions of NGF and BDNF were significantly (P<0.01) increased in cortex (neuron) and striatum (glia) of rats under the exercise condition. Significant (P<0.01) increases in microvessel density were found in striatum. Physical activity reduced stroke damage. The reduced brain damage may be attributable to angiogenesis and neurotrophin overexpression in brain regions supplied by the MCA following exercise.

Animals↗
PubMed2003

Analysis of genetic diversity of hordein in wild close relatives of barley from Tibet.

We analyzed genetic diversity in the storage protein hordein encoded at Hor-1, Hor-2 and Hor-3 loci in seeds from 211 accessions of wild close relatives of barley, Hordeum vulgare ssp. agriocrithon and H. vulgare ssp. spontaneum. Altogether 32, 27 and 13 different phenotypes were found for Hor-1, Hor-2 and Hor-3, respectively. A comparison of our results with those of previous studies indicates that Tibetan samples reflect the highest diverse level of hordein phenotypes when compared to samples from Israel and Jordan. This high degree of polymorphism supports the hypothesis that Tibet is one of the original centers of H. vulgare L.

Electrophoresis, Polyacrylamide Gel↗
PubMed2003

Ontogeny and specificities of mucosal and blood human immunodeficiency virus type 1-specific CD8(+) cytotoxic T lymphocytes.

Induction of adaptive immunity to human immunodeficiency virus type 1 (HIV-1) at the mucosal site of transmission is poorly understood but crucial in devising strategies to control and prevent infection. To gain further understanding of HIV-1-specific T-cell mucosal immunity, we established HIV-1-specific CD8(+) cytotoxic T-lymphocyte (CTL) cell lines and clones from the blood, cervix, rectum, and semen of 12 HIV-1-infected individuals and compared their specificities, cytolytic function, and T-cell receptor (TCR) clonotypes. Blood and mucosal CD8(+) CTL had common HIV-1 epitope specificities and major histocompatibility complex restriction patterns. Moreover, both systemic and mucosal CTL lysed targets with similar efficiency, primarily through the perforin-dependent pathway in in vitro studies. Sequence analysis of the TCRbeta VDJ region revealed in some cases identical HIV-1-specific CTL clones in different compartments in the same HIV-1-infected individual. These results clearly establish that a subset of blood and mucosal HIV-1-specific CTL can have a common origin and can traffic between anatomically distinct compartments. Thus, these effectors can provide immune surveillance at the mucosa, where rapid responses are needed to contain HIV-1 infection.

Cervix Uteri↗
PubMed2002

Purification, crystallization and X-ray analysis of swine vesicular disease virus.

Swine vesicular disease virus (SVDV) is the etiological agent of swine vesicular disease, a highly contagious disease in pigs, and is related to coxsackie B virus. Crystalline arrays of SVDV can be observed in the cytoplasm of cells 4.5 h after inoculation to porcine kidney cells (IBRS-2 cells). Crystals of the JX/78 strain of SVDV were obtained from virus in two wells of crystallization conditions and present preliminary X-ray data to 3.6 A resolution.

Crystallization↗
PubMed2002

Developmentally regulated monocyte recruitment and bone resorption are modulated by functional deletion of the monocytic chemoattractant protein-1 gene.

Tooth eruption involves the movement of a tooth from its site of development within the alveolar bone to its functional position in the oral cavity. Because this process is dependent upon monocytes and formation of osteoclasts, it represents an excellent model for examination of these processes under developmental regulation. We investigated the functional role of monocyte chemoattractant protein-1 (MCP-1) in monocyte recruitment and its impact on bone resorption by examining each parameter in MCP-1(-/-) mice as compared with wild-type controls during tooth eruption. The peak number of monocytes occurred on day 5 in the MCP-1(-/-) mice and on day 9 in the wild-type mice. The peak number of osteoclasts followed the same pattern, occurring sooner in the MCP-1(-/-) (day 5) than in wild-type mice (day 9). Consistent with this, MCP-1(-/-) mice had an accelerated rate of tooth eruption in the early phase when the teeth first entered the oral cavity as compared with the wild-type mice. However, there was accelerated eruption in the wild-type group in the later phase of tooth eruption. When examined at the molecular level, inducible nitric oxide synthase (iNOS) and interleukin-11 and -6 were expressed at considerably higher levels in the experimental group with accelerated tooth eruption. This is the first report identifying these factors as potential modulators of bone resorption that can accelerate the rate of tooth eruption. We conclude that, at early timepoints, monocyte recruitment occurs by MCP-1-independent mechanisms. However, at a later timepoint, MCP-1 may play a contributory role in the recruitment of monocytic cells, allowing the wild-type animals to catch up.

Animals↗