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Tong Cao

Publications and source records attributed to Tong Cao.

At least 55 records · Page 3Linked to original sources
PubMed2005

[Niche of the mosses on floor in Shanghai City].

The mosses on the floor of 22 sites at 20 main parks and 2 chemical plants in Shanghai were sampled, and 75 moss species were recorded. Their niche breadths were calculated by Levins equation. The results indicated that most moss species had rather narrow niche breadth, 68% of them with a niche breadth less than 0.1. The relationship between species number (N) and their niche breadth (B) followed the model N = 0.344 x e(-0.0377B), R = 0.9684. The niche overlaps of 39 main moss species (important value > 0.1) were calculated by Wang's equation. Based on their niche overlaps, the ordination plot of Principal Axes Analysis (PAA) and the Minimal Spanning Tree (MST) were drawn. The results showed that five ecological groups of the 39 moss species related to different habitats could be identified.

Bryophyta↗
PubMed2005

Intracellular antibodies (intrabodies) versus RNA interference for therapeutic applications.

Currently there are two technology platforms for the ablation of protein function: (a) RNAi-mediated gene-silencing at the post-transcriptional level, and (b) intrabody knockout of protein function at the post-translational level. Both approaches hold much promise for therapeutic applications. The pertinent question is how to choose between these alternative approaches. This commentary examines the advantages and disadvantages of these newly-emerging technology platforms. The RNAi approach is much less technically challenging than the intrabody-mediated knockout of protein function, but its major limitation is non-specificity. Although it is time-consuming and labor-intensive to generate intrabodies for specific intracellular protein targets, a much higher level of specificity can be attained. Ultimately, the choice between these strategies depend on the specific application in question, as well as on further technical advances in both technology platforms.

Antibodies↗
PubMed2005

[Detrended correspondence analysis of phenetic relationships of bryophytes based on FTIR spectra].

Bryophytes are important high plants. However, the plants of bryophyte are small in size with few identification characters. The identification of plant samples using Fourier transform infrared spectrometer with OMNI collector is simple, convenient, fast and accurate. In the present paper, Fourier transform infrared spectrometer with OMNI collector was applied to gain the infrared spectra of 30 samples belonging to 26 bryophyte species. Based on the indices of wave number-absorbance, the differences of the 30 infrared spectra were compared by the method of Detrended Correspondence Analysis (DCA). The results showed that there is good correspondence between the position relationship of DCA two-dimensional plot of the samples based on the indices of wave number-absorbance of FTIR spectra and their classification relationship. Therefore, it is practical to apply the infrared spectra to identifying the false sample from the true one in medicine bryophytes.

Bryophyta↗
PubMed2005

Late-adhering human embryonic stem cell clumps during serial passage can yield morphologically 'normal-looking' colonies.

During serial passage of human embryonic stem (hES) cells, freshly-seeded hES cell clumps that do not adhere to the newly-plated murine embryonic fibroblast (MEF) feeder layer after culturing overnight, are routinely discarded with the changing of fresh culture media. Preliminary observations revealed that non-adhered hES cell clumps that were still viable possessed a distinct, rounded morphology with 'sharp,' clearly-defined edges. Typically >90% of 'viable' hES cell clumps with such morphology adhered after a further 24 hr of culture on newly-plated MEF. The remaining non-adhered cell clumps that had ill-defined jagged edges could represent either non-viable hES cells or senescent MEF carried over from the previous sub-culture. Virtually none of these adhered to the newly-plated MEF feeder layer. The overwhelming majority of 'viable,' late-adhering hES cell clumps (typically >90%) gave rise to morphologically 'normal-looking' hES colonies, which appeared to remain undifferentiated. Additionally, hES cell clumps that were attached together with the majority of the passaged colonies, but were somewhat delayed in the adhesion process, compared to neighbouring colonies, also gave rise to morphologically 'normal-looking' undifferentiated colonies that were virtually indistinguishable from neighbouring colonies. Hence, it may be useful to retain late-adhering hES cell clumps during serial passage of hES cells, rather than discarding them.

Cell Adhesion↗
PubMed2004

Strategies for directing the differentiation of stem cells into the osteogenic lineage in vitro.

A major area in regenerative medicine is the application of stem cells in bone reconstruction and bone tissue engineering. This will require well-defined and efficient protocols for directing the differentiation of stem cells into the osteogenic lineage, followed by their selective purification and proliferation in vitro. The development of such protocols would reduce the likelihood of spontaneous differentiation of stem cells into divergent lineages on transplantation, as well as reduce the risk of teratoma formation in the case of embryonic stem cells. Additionally, such protocols could provide useful in vitro models for studying osteogenesis and bone development, and facilitate the genetic manipulation of stem cells for therapeutic applications. The development of pharmokinetic and cytotoxicity/genotoxicity screening tests for bone-related biomaterials and drugs could also use protocols developed for the osteogenic differentiation of stem cells. This review critically examines the various strategies that could be used to direct the differentiation of stem cells into the osteogenic lineage in vitro.

Animals↗
PubMed2004

Strategies for directing the differentiation of stem cells into the cardiomyogenic lineage in vitro.

Most studies on stem cell transplantation therapy on myocardially infarcted animal models and phase-I human clinical trials have focused on the use of undifferentiated stem cells. There is a strong possibility that some degree of cardiomyogenic differentiation of stem cells in vitro prior to transplantation would result in higher engraftment efficiency, as well as enhanced myocardial regeneration and recovery of heart function. Additionally, this may also alleviate the probability of spontaneous differentiation of stem cells into undesired lineages and reduces the risk of teratoma formation, in the case of embryonic stem cells. The development of efficient protocols for directing the cardiomyogenic differentiation of stem cells in vitro will also provide a useful model for molecular studies and genetic manipulation. This review therefore critically examines the various techniques that could possibly be used to direct and control the cardiomyogenic differentiation of stem cells in vitro.

Animals↗
PubMed2004

An overview and synopsis of techniques for directing stem cell differentiation in vitro.

The majority of studies on stem cell differentiation have so far been based in vivo, on live animal models. The usefulness of such models is limited, since it is much more technically challenging to conduct molecular studies and genetic manipulation on live animal models compared to in vitro cell culture. Hence, it is imperative that efficient protocols for directing stem cell differentiation into well-defined lineages in vitro are developed. The development of such protocols would also be useful for clinical therapy, since it is likely that the transplantation of differentiated stem cells would result in higher engraftment efficiency and enhanced clinical efficacy, compared to the transplantation of undifferentiated stem cells. The in vitro differentiation of stem cells, prior to transplantation in vivo, would also avoid spontaneous differentiation into undesired lineages at the transplantation site, as well as reduce the risk of teratoma formation, in the case of embryonic stem cells. Hence, this review critically examines the various strategies that could be employed to direct and control stem cell differentiation in vitro.

Animals↗
PubMed2004

Potential utility of cell-permeable transcription factors to direct stem cell differentiation.

Application of embryonic and adult stem cells in regenerative medicine will require efficient protocols for directing stem cell differentiation into well-defined lineages. Differentiation induced by exogenous cytokines, growth factors, or extracellular matrix components will require extended in vitro culture that would delay autologous transplantation and may well alter the immunogenicity of cultured cells. Genetic modulation to direct stem cell differentiation may obviate prolonged culture, but safety concerns preclude clinical application of genetically altered cells in the foreseeable future A novel alternative would be to incorporate protein transduction domains (PTDs) into recombinant transcription factors that play important roles in somatic differentiation. Such protein-engineered transcription factors would then have the ability to translocate across the cell membrane and be internalized within the cytosol, where they would act as paracrine signaling molecules. Upon internalization, the recombinant transcription factors would only have a limited active half-life, so that their effects may only be transient. However, this could provide sufficient stimulus for initiating stem cell differentiation into a required lineage.

Cell Differentiation↗
PubMed2004

Directing stem cell differentiation into the chondrogenic lineage in vitro.

A major area in regenerative medicine is the application of stem cells in cartilage tissue engineering and reconstructive surgery. This requires well-defined and efficient protocols for directing the differentiation of stem cells into the chondrogenic lineage, followed by their selective purification and proliferation in vitro. The development of such protocols would reduce the likelihood of spontaneous differentiation of stem cells into divergent lineages upon transplantation, as well as reduce the risk of teratoma formation in the case of embryonic stem cells. Additionally, such protocols could provide useful in vitro models for studying chondrogenesis and cartilaginous tissue biology. The development of pharmacokinetic and cytotoxicity/genotoxicity screening tests for cartilage-related biomaterials and drugs could also utilize protocols developed for the chondrogenic differentiation of stem cells. Hence, this review critically examines the various strategies that could be used to direct the differentiation of stem cells into the chondrogenic lineage in vitro.

Animals↗
PubMed2004

[Distribution patterns of moss species in Shanghai city].

The mosses on the floor of 22 sites at 20 main parks and 2 chemical plants in Shanghai city were investigated and sampled. Based on 75 recorded moss species and their coverage, Two-way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA) were used to analyze their distribution patterns. The results showed that the study sites could be identified as three groups. Group 1 included two chemical plants and two parks at the center of the city, with 23 moss species and the smallest total coverage of 21.29%; group 2 included part of the parks at the center of the city and surrounding areas, with 44 moss species and total coverage of 37.94%; and group 3 mainly included the parks at surrounding areas and suburbs of the city, with 49 moss species and total coverage of 49.66%. The results reflected a certain correlation of the distribution of moss species with different habitats and polluted and disturbed environments in the city.

Bryophyta↗
PubMed2004

[Environmental physiological characteristics of some mosses in Shanghai: a preliminary study].

The preliminary study on the environmental physiological characteristics of bryophytes collected from Shanghai area, including their responses to drought, temperature, humidity, light and growth substrate, as well as their tissue culture technology showed that different species of bryophytes under same conditions and the same species under different conditions had different drought resistance. Adding organic matter to sand soil and short-illumination benefited the growth of bryophytes. Treating with proper growth hormones could accelerate the reproduction and growth of bryophyte. Hogland medium was suitable for the tissue culture of bryophytes.

Bryophyta↗
PubMed2003

Scaffold design and in vitro study of osteochondral coculture in a three-dimensional porous polycaprolactone scaffold fabricated by fused deposition modeling.

Tissue engineering offers an alternative method that can overcome some of the existing drawbacks of current articular defect repair methods because articular cartilage has a limited capacity to respond to injury. The solution may lie in the design of a three-dimensional load-bearing scaffold. Here we describe the tissue engineering of an osteochondral construct by coculturing osteogenic cells and chondrogenic cells on a three-dimensional load-bearing bioresorbable polymer scaffold. Porous polycaprolactone scaffolds were designed and fabricated via fused deposition modeling. Osteogenic cells were seeded and precultured in one-half of the partitioned scaffolds. Chondrogenic cells were later seeded into the other half. The cell-seeded scaffolds were cultured in a coculture medium. Both cell types proliferated, migrated, linked in their scaffold compartments, and integrated at the interface. Osteoblasts and chondrocytes produced different extracellular matrices in each scaffold compartment. Mineralized nodules deposited in the osteogenic cell seeded compartment. High osteocalcin was detected in precultured osteogenic cell supernatant and high alkaline phosphatase was detected in the coculture supernatant of osteochondral constructs. This study suggests that a tissue-engineered osteochondral construct with a three-dimensional polycaprolactone scaffold has the potential for osteochondral defect repair.

Alkaline Phosphatase↗
PubMed2003

[Species diversity of floor bryophyte communities in Bogda Mountains, Xinjiang].

By means of species similarity coefficient and species diversity index, the characteristics of species diversity of floor bryophyte communities in Bogda Mountain, Xinjiang were studied. The results showed that the bryoflora of Bogda Mountain had the characteristics of richness and complexion. There were 186 floor species (including infraspecies taxa) belonging to 73 genera of 32 families. The species similarity between mountain desert and mountain grassland belt was the highest (0.6809), while that between mountain forest and alpine cushion belt was the lowest (0.1342). The bryophyte community in mountain forest was the ominant one among the floor bryophyte communities. The bryophyte community in mountain forest had the richest species diversity, and the mountain forest was the distribution center of bryophyte diversity and the key area for bryophyte diversity conservation in Bogda Mountain area.

Bryophyta↗
PubMed2002

[Response of bryophytes to global change and its bioindicatortation].

Bryophytes are sensitive to atmosphere components concentration and global climate change resulted from relatively simple structures. Bryophyte is an ideal kind of biological indicator of global changes, environmental pollution, nutrient condition, forest integrity and ecosystem health. In order to use bryophytes as indicators to environmental and global changes, further studies on response and adaptation of bryophytes to the global changes are needed.

Animals↗
PubMed2002

[Principal axes analyses on population genetic differentiation of Plantago asiatica in Zhejiang].

Eight populations of Plantago asiatica collected from Zhejiang were analyzed using random amplified polymorphic DNA (RAPD). Eighteen of the 60 random primers were selected. 186 bands were amplified by the 18 primers, and 68.70% of them were polymorphic. Jaccard coefficient was applied to compare the genetic of these eight populations based on the RAPD data. Three-dimensional ordination plot of the eight populations based on the Jaccard coefficient was constructed by using principal axes analysis (PAA). The results showed that the genetic differentiation of eight populations could be explained to a certain extent by their geographical location and altitude.

DNA, Plant↗
PubMedDate not supplied

Reduced mitotic activity at the periphery of human embryonic stem cell colonies cultured in vitro with mitotically-inactivated murine embryonic fibroblast feeder cells.

This study attempted to investigate whether different levels of mitotic activity exist within different physical regions of a human embryonic stem (hES) cell colony. Incorporation of 5-bromo-2-deoxyuridine (BrdU) within newly-synthesized DNA, followed by immunocytochemical staining was used as a means of detecting mitotically-active cells within hES colonies. The results showed rather surprisingly that the highest levels of mitotic activity are primarily concentrated within the central regions of hES colonies, whereas the peripheral regions exhibited reduced levels of cellular proliferation. Two hypothetical mechanisms are therefore proposed for hES colony growth and expansion. Firstly, it is envisaged that the less mitotically-active hES cells at the periphery of the colony are continually migrating outwards, thereby providing space for newly-divided daughter cells within the more mitotically-active central region of the hES colony. Secondly, it is proposed that the newly-divided hES cells within the central region of the colony somehow migrate to the outer periphery. This could possibly explain why the periphery of hES colonies are less mitotically-active, since there would obviously be an extended time-lag before newly-divided daughter cells are ready again for the next cell division. Further investigations need to be carried out to characterize the atypical mechanisms by which hES colonies grow and expand in size.

Animals↗
PubMedDate not supplied

Culture media conditioned by heat-shocked osteoblasts enhances the osteogenesis of bone marrow-derived mesenchymal stromal cells.

Osteogenic cells differentiated from bone marrow-derived mesenchymal stromal cells (MSC) hold much promise in bone tissue engineering and reconstructive surgery. There is a dire need for well-defined and efficient protocols to promote the osteogenesis of ex vivo cultured MSC. Hence, this study investigated whether a combination of chemical stimuli (ascorbic acid, beta-glycerophosphate and dexamethasone) and culture media conditioned by a human foetal osteoblast cell line (hFOB) had any synergistic effect on the osteogenesis of MSC. Conditioned media with or without prior heat shock treatment (42 degrees C for 1 h) of the hFOB cell line, were collected and tested on rabbit MSC cultures, in the presence and absence of chemical stimuli. Osteogenic differentiation of MSC was assessed on both day 14 and 21 of ex vivo culture. The results showed conclusively that conditioned media promoted osteogenesis of MSC, which was further enhanced by prior heat shock-treatment of the hFOB cells, as well as by the presence of chemical stimuli. Among all experimental groups, the combination of culture medium conditioned by heat shocked hFOB cells together with chemical stimuli, exhibited the highest level of calcium mineralization, as assessed by Von Kossa staining. This provides clear evidence of a synergistic effect of conditioned media, heat shock and chemical stimuli. It is hoped that the data may contribute to the development of a more well-defined and efficient in vitro culture protocol to promote the osteogenesis of MSC for both clinical and non-clinical applications.

Animals↗