Biomedical subjects

Kan Wang

Publications and source records attributed to Kan Wang.

18 recordsLinked to original sources

PubMed2026

Effects of intensive blood pressure control on cardio-kidney outcomes by KDIGO risk categories: a Post Hoc analysis of ACCORD-BP and SPRINT trials.

The effects of intensive systolic blood pressure (SBP) control on cardiovascular (CV) and kidney outcomes across different Kidney Disease Improving Global Outcomes (KDIGO) risk categories remain unclear. We performed a secondary analysis of the Systolic Blood Pressure Intervention Trial (SPRINT) and the SPRINT-eligible Action to Control Cardiovascular Risk in Diabetes Blood Pressure (ACCORD-BP) trial. Participants were categorized into low, moderate, and high/very-high KDIGO risk groups. The primary outcomes were composite adverse CV events (defined as nonfatal myocardial infarction (MI), nonfatal stroke, fatal or hospitalized heart failure (HF), and CV mortality) and composite adverse kidney events (defined as a sustained decline in eGFR of ≥ 40% and end-stage kidney disease (ESKD)). We found that intensive BP control reduced the risk of composite CV events (HR 0.68; 95% CI 0.59-0.78), with attenuated benefits in higher KDIGO risk categories (P for interaction = 0.055). This interaction was mainly driven by nonfatal MI and fatal or hospitalized HF (both P for interaction < 0.05). Intensive BP control increased the risk of composite kidney events (HR 1.88; 95% CI 1.52-2.33), mainly in low- and moderate-risk groups rather than in high/very-high risk groups (P for interaction = 0.04). Similar patterns were observed for sustained eGFR decline (P for interaction = 0.03), but not for ESKD (HR 1.05; 95% CI 0.74-1.48; P for interaction = 0.71). The KDIGO risk classification modified the effects of intensive BP control. Balancing CV benefits against potential kidney impacts in patients with different KDIGO risks during intensive BP treatment is recommended. Trial Registration: ClinicalTrials.gov Identifiers: NCT01206062 (SPRINT) and NCT00000620 (ACCORD).

Cardiovascular outcome↗

PubMed2006

Gene expression patterns during somatic embryo development and germination in maize Hi II callus cultures.

Gene expression patterns were profiled during somatic embryogenesis in a regeneration-proficient maize hybrid line, Hi II, in an effort to identify genes that might be used as developmental markers or targets to optimize regeneration steps for recovering maize plants from tissue culture. Gene expression profiles were generated from embryogenic calli induced to undergo embryo maturation and germination. Over 1,000 genes in the 12,060 element arrays showed significant time variation during somatic embryo development. A substantial number of genes were downregulated during embryo maturation, largely histone and ribosomal protein genes, which may result from a slowdown in cell proliferation and growth during embryo maturation. The expression of these genes dramatically recovered at germination. Other genes up-regulated during embryo maturation included genes encoding hydrolytic enzymes (nucleases, glucosidases and proteases) and a few storage genes (an alpha-zein and caleosin), which are good candidates for developmental marker genes. Germination is accompanied by the up-regulation of a number of stress response and membrane transporter genes, and, as expected, greening is associated with the up-regulation of many genes encoding photosynthetic and chloroplast components. Thus, some, but not all genes typically associated with zygotic embryogenesis are significantly up or down-regulated during somatic embryogenesis in Hi II maize line regeneration. Although many genes varied in expression throughout somatic embryo development in this study, no statistically significant gene expression changes were detected between total embryogenic callus and callus enriched for transition stage somatic embryos.

DNA, Plant↗

PubMed2006

Improved Agrobacterium-mediated transformation of three maize inbred lines using MS salts.

Transformation technology as a research or breeding tool to improve maize is routinely used in most industrial and some specialized public laboratories. However, transformation of many inbred lines remains a challenging task, especially when using Agrobacterium tumefaciens as the delivery method. Here we report success in generating transgenic plants and progeny from three maize inbred lines using an Agrobacterium-mediated standard binary vector system to target maize immature embryos. Eleven maize inbred lines were pre-screened for transformation frequency using N6 salts. A subset of three maize inbred lines was then systematically evaluated for frequency of post-infection embryogenic callus induction and transformation on four media regimes: N6 or MS salts in each of two distinct media backgrounds. Transgenic plants recovered from inbred lines B104, B114, and Ky21 were analyzed for transgene integration, expression, and transmission. Average transformation frequencies of 6.4% (for B104), 2.8% (for B114), and 8% (for Ky21) were achieved using MS salts. Availability of Agrobacterium-mediated maize inbred line transformation will improve future opportunities for maize genetic and functional genomic studies.

Blotting, Southern↗

PubMed2006

Asymmetric claisen rearrangements enabled by catalytic asymmetric Di(allyl) ether synthesis.

Merging the catalytic asymmetric synthesis of di(allyl) ethers with ensuing olefin isomerization-Claisen rearrangement (ICR) reactions provides a convenient, two-step route to asymmetric aliphatic Claisen rearrangements from easily obtained starting materials. These reactions deliver the 2,3-disubstituted 4-pentenal derivatives characteristic of aliphatic Claisen rearrangements with excellent relative and absolute stereocontrol. A catalytic enantioselective synthesis of the (+)-calopin dimethyl ether demonstrates the utility of this reaction technology in asymmetric synthesis enterprises.

Allyl Compounds↗

PubMed2006

Maize (Zea mays L.).

Agrobacterium tumefaciens-mediated transformation is an effective method for introducing genes into maize. In this chapter, we describe a detailed protocol for genetic transformation of the maize genotype Hi II. Our starting plant material is immature embryos cocultivated with an Agrobacterium strain carrying a standard binary vector. In addition to step-by-step laboratory transformation procedures, we include extensive details in growing donor plants and caring for transgenic plants in the greenhouse.

Agrobacterium tumefaciens↗

PubMed2006

Analysis of immune response in young and aged mice vaccinated with corn-derived antigen against Escherichia coli heat-labile enterotoxin.

Enterotoxigenic strains of Escherichia coli produce a heat-labile holotoxin (LT), which causes diarrhea. We engineered corn seeds to produce LT-B, the nontoxic subunit of LT, to serve as a plant-derived vaccine to traveler's diarrhea and as an adjuvant for co-administered proteins. We previously demonstrated that a strong mucosal and systemic antibody response is elicited in young mice with oral administration of corn-derived LT-B. The present study examined systemic and mucosal antibody responses to LT-B in young and aged mice, and recall responses to oral administration and injection of LT-B in aged mice. Specific IgA and IgG antibodies were detectable during an 11-mo period, although the concentration of antigen-specific antibodies declined gradually. Booster by feeding or injection dramatically increased the concentration of specific IgA from that seen in young mice. Specific IgG levels were boosted to concentrations similar to those in young mice. This effect may be age-dependent and related to prior immunization exposure. Analysis of the antibody response of naïve aged mice against corn-derived LT-B demonstrated an age-related suppression in specific IgG production, but not specific IgA. These results may provide important information for edible vaccine strategies for young and aged individuals.

Administration, Oral↗

PubMed2005

Improved cotyledonary node method using an alternative explant derived from mature seed for efficient Agrobacterium-mediated soybean transformation.

The utility of transformation for soybean improvement requires an efficient system for production of stable transgenic lines. We describe here an improved cotyledonary node method using an alternative explant for Agrobacterium tumefaciens-mediated soybean transformation. We use the term "half-seed" to refer to this alternative cotyledonary explant that is derived from mature seed of soybean following an overnight imbibition and to distinguish it from cotyledonary node derived from 5-7-day-old seedlings. Transformation efficiencies using half-seed explants ranged between 1.4 and 8.7% with an overall efficiency of 3.8% based on the number of transformed events that have been confirmed in the T1 generation by phenotypic assay using the herbicide Liberty (active ingredient glufosinate) and by Southern analysis. This efficiency is 1.5-fold higher than the cotyledonary node method used in our laboratory. Significantly, the half-seed system is simple and does not require deliberate wounding of explants, which is a critical and technically demanding step in the cotyledonary node method.

Benzyl Compounds↗

PubMed2005

[A simulation study of electrical impedance scan-imaging based on a phantom].

OBJECTIVE: To testify the feasibility of electrical impedance scanning (EIS) imaging and to classify the factors influencing EIS imaging at the early stage of electrical impedance scanning breast imaging study. METHOD: Based on the EIS experiment workplace, a phantom to simulate the distribution of breast tissue was designed. Using NaCl solution and agar block with different conductance, three kinds of electric fields disturbances were simulated. RESULT: Different electric fields disturbance induced by different conductance distributions bring different imaging effects. CONCLUSION: The imaging based on the theory of EIS is feasible. Initiative factors influencing EIS imaging are confirmed.

Agar↗

PubMed2004

Expression of the Nicotiana protein kinase (NPK1) enhanced drought tolerance in transgenic maize.

Drought is one of the most important abiotic stresses affecting the productivity of maize. Previous studies have shown that expression of a mitogen-activated protein kinase kinase kinase (MAPKKK) gene activated an oxidative signal cascade and led to the tolerance of freezing, heat, and salinity stress in transgenic tobacco. To analyse the role of activation of oxidative stress signalling in improving drought tolerance in major crops, a tobacco MAPKKK (NPK1) was expressed constitutively in maize. Results show that NPK1 expression enhanced drought tolerance in transgenic maize. Under drought conditions, transgenic maize plants maintained significantly higher photosynthesis rates than did the non-transgenic control, suggesting that NPK1 induced a mechanism that protected photosynthesis machinery from dehydration damage. In addition, drought-stressed transgenic plants produced kernels with weights similar to those under well-watered conditions, while kernel weights of drought-stressed non-transgenic control plants were significantly reduced when compared with their non-stressed counterparts.

Disasters↗

PubMed2004

Expression of an active tobacco mitogen-activated protein kinase kinase kinase enhances freezing tolerance in transgenic maize.

Cold acclimation is the major process that prepares plants for freezing tolerance. In addition to extensive transcription regulation by cold-inducible master transcription factors, oxidative stress signaling has been postulated to play a role in freezing tolerance. Activation of oxidative signaling through the expression of an active mitogen-activated protein kinase kinase kinase provided benefits in transgenic tobacco at freezing temperature bypassing cold acclimation. Because involvement of the mitogen-activated protein kinase cascade in oxidative stress signaling is evolutionarily conserved in eukaryotes from yeast to mammals, we tested the effect of expressing a heterologous tobacco mitogen-activated protein kinase kinase kinase (Nicotiana PK1), which can mimic H(2)O(2) signaling, in a major cereal crop. We demonstrate that low-level but constitutive expression of the Nicotiana PK1 gene enhances freezing tolerance in transgenic maize plants that are normally frost sensitive. Our results suggest that a new molecular approach can be designed to genetically enhance freezing tolerance in important crops.

Acclimatization↗

PubMed2004

Leaf senescence is delayed in maize expressing the Agrobacterium IPT gene under the control of a novel maize senescence-enhanced promoter.

We have genetically modified maize plants to delay leaf senescence. A senescence-enhanced promoter from maize (P(SEE1)) was used to drive expression of the Agrobacterium cytokinin biosynthesis gene IPT in senescing leaf tissue. Three maize lines expressing IPT from P(SEE1), Sg1, Sg2 and Sg3, were analysed in detail, representing mild, intermediate and extreme expression, respectively, of the delayed-senescence phenotype. Backcross populations segregating for the presence or absence of the P(SEE1Xba)IPTNOS transgene also simultaneously segregated for the senescence phenotype. At the time of ear leaf emergence, individuals of lines Sg1 and Sg2 segregating for the presence of the transgene carried about three fewer senescing leaves than control (transgene-minus) segregants, and IPT transcript levels were higher in leaves at incipient senescence than in young leaves. Leaves of transgenic Sg3 plants were significantly greener than controls and progressed directly from fully green to bleached and dead without an intervening yellowing phase. IPT transcript abundance in this line was not related to the initiation of senescence. Extended greenness was accompanied by a delay in the loss of photosynthetic capacity with leaf age. The delayed-senescence trait was associated with relatively minor changes in morphology and development. The phenotype was particularly emphasized in plants grown in low soil nitrogen. The reduced ability of the extreme transgenic line Sg3 to recycle internal nitrogen from senescing lower leaves accounted for significant chlorosis in emerging younger leaves when plants were grown in low nutrient conditions. This study demonstrates that the agronomically important delayed-senescence ('stay-green') trait can be engineered into a monocot crop, and is the first example outside Arabidopsis of senescence modification using a homologous senescence-enhanced promoter.

Journal Article↗

PubMed2004

[Influence of climatic factor on formation and development of TCM].

Climatic factors influence health, physiological and pathological condition of human being, and then influence medicine. Through discussing the relationship between climatic type and traditional Chinese medical theory, relationship between climatic changes and formation and development of Cold-Warm School, and regional characteristic of Ling Nan medicine, conclusion can be made: firstly, traditional Chinese medical theory has some regional limit because its formation was influenced by climatic factor; secondly, climatic changes in history is the important cause leading to formation and vicissitude of Cold-Warm School in TCM history; thirdly, as an important branch of TCM, Ling Nan medicine reflects its own climatic characteristic and shows good adaptability and promising prospects of TCM.

Humans↗

PubMed2003

Regulation of the neuronal nicotinic acetylcholine receptor by SRC family tyrosine kinases.

Src family kinases (SFKs) are abundant in chromaffin cells that reside in the adrenal medulla and respond to cholinergic stimulation by secreting catecholamines. Our previous work indicated that SFKs regulate acetylcholine- or nicotine-induced secretion, but the site of modulatory action was unclear. Using whole cell recordings, we found that inhibition of SFK tyrosine kinase activity by PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo(3,4-d)pyrimidine) treatment or expression of a kinase-defective c-Src reduced the peak amplitude of nicotine-induced currents in chromaffin cells or in human embryonic kidney cells ectopically expressing functional neuronal alpha3beta4alpha5 acetylcholine receptors (AChRs). Conversely, the phosphotyrosine phosphatase inhibitor, sodium vanadate, or expression of mutationally activated c-Src resulted in enhanced current amplitudes. These results suggest that SFKs and putative phosphotyrosine phosphatases regulate the activity of AChRs by opposing actions. This proposed model was supported further by the findings that SFKs physically associate with the receptor and that the AChR is tyrosine-phosphorylated.

Cell Line↗

PubMed2003

Catalyzed olefin isomerization leading to highly stereoselective Claisen rearrangements of aliphatic allyl vinyl ethers.

Iridium(I)-catalyzed olefin isomerization in bis(allyl) ethers is integrated into a generally applicable strategy for affecting highly stereoselective Claisen rearrangements. Catalyzed alkene isomerization affords allyl vinyl ethers from easily prepared di(allyl) ethers; direct thermolysis of these reaction mixtures leads to highly diastereoselective [3,3] sigmatropic rearrangements affording syn-2,3-dialkyl-4-pentenal derivatives. An easily executed strategy for realizing asymmetric variants of the isomerization-Claisen rearrangement (ICR) reactions is also described.

Aldehydes↗

PubMed2003

Localization of a bacterial protein in starch granules of transgenic maize kernels.

The B subunit of Escherichia coli heat labile enterotoxin (LT-B) is a potent oral immunogen with potential for use as a vaccine, a carrier molecule to deliver antigens to gut-associated lymphoid tissues, and possibly an adjuvant to make coadministered vaccines more effective. LT-B produced in plants was shown to be functional and immunogenic in animals and humans. In this work, we show that maize-derived LT-B is strongly associated with starch granules in endosperm. Using immunogold labeling/electron microscopy, cell fractionation, and protein analysis techniques, we observed that LT-B protein could be detected both internally and externally in starch granules. This strong association confers an effective copurification of the antigen with the starch fraction of maize kernels, thermostability desirable in maize processing, and resistance to peptic degradation in simulated gastric fluid digests, an important attribute for an orally delivered antigen.

Bacterial Proteins↗

PubMed2002

A functional antigen in a practical crop: LT-B producing maize protects mice against Escherichia coli heat labile enterotoxin (LT) and cholera toxin (CT).

We have produced a functional heat labile enterotoxin (LT-) B subunit of Escherichia coli in maize. LT-B is a multimeric protein that presents an ideal model for an edible vaccine, displaying stability in the gut and inducing mucosal and systemic immune responses. Transgenic maize was engineered to synthesize the LT-B polypeptides, which assembled into oligomeric structures with affinity for G(M1) gangliosides. We orally immunized BALB/c mice by feeding transgenic maize meal expressing LT-B or non-transgenic maize meal spiked with bacterial LT-B. Both treatments stimulated elevated IgA and IgG antibodies against LT-B and the closely related cholera toxin B subunit (CT-B) in serum, and elevated IgA in fecal pellets. The transgenic maize induced a higher anti-LT-B and anti-CT-B mucosal and serum IgA response compared to the equivalent amount of bacterial LT-B spiked into maize. Following challenge by oral administration of the diarrhea inducing toxins LT and CT, transgenic maize-fed mice displayed reduced fluid accumulation in the gut compared to non-immunized mice. Moreover, the gut to carcass ratio of immunized mice was not significantly different from the PBS (non-toxin) challenged control group. We concluded that maize-synthesized LT-B had features of the native bacterial LT-B such as molecular weight, G(M1) binding ability, and induction of serum and mucosal immunity. We have demonstrated that maize, a major food and feed ingredient, can be efficiently transformed to produce, accumulate, and store a fully assembled and functional candidate vaccine antigen.

Administration, Oral↗

PubMed2002

Agrobacterium tumefaciens-mediated transformation of maize embryos using a standard binary vector system.

We have achieved routine transformation of maize (Zea mays) using an Agrobacterium tumefaciens standard binary (non-super binary) vector system. Immature zygotic embryos of the hybrid line Hi II were infected with A. tumefaciens strain EHA101 harboring a standard binary vector and cocultivated in the presence of 400 mg L-1 L-cysteine. Inclusion of L-cysteine in cocultivation medium lead to an improvement in transient beta-glucuronidase expression observed in targeted cells and a significant increase in stable transformation efficiency, but was associated with a decrease in embryo response after cocultivation. The average stable transformation efficiency (no. of bialaphos-resistant events recovered per 100 embryos infected) of the present protocol was 5.5%. Southern-blot and progeny analyses confirmed the integration, expression, and inheritance of the bar and gus transgenes in R0, R1, and R2 generations of transgenic events. To our knowledge, this represents the first report in which fertile, stable transgenic maize has been routinely produced using an A. tumefaciens standard binary vector system.

Agrobacterium tumefaciens↗

PubMed2002

[Epidemic trends of pulmonary tuberculosis and case finding in Henan province].

OBJECTIVE: Based on the data of the 4th national epidemiological survey in 2000 in Henan province, to obtain the trends of epidemic situation of pulmonary tuberculosis, and to analyze the methods of case finding. METHODS: The detection methods such as X-ray, sputum examination and PPD were used to diagnose active pulmonary tuberculosis from sampling population. RESULTS: The prevalence of active pulmonary tuberculosis is 497 per 100 000 population, the prevalence of smear positive pulmonary tuberculosis is 132 per 100 000 population. Comparing to the third survey in 1990, the reduction rate of prevalence of smear positive pulmonary tuberculosis is 6.15%, the annual reduction rate only 0.63%, indicating the prevalence declined very slowly in ten years. The rate of case finding increased by 6.6% after sputum specimens increased from 2 to 3. CONCLUSIONS: The epidemic status of pulmonary tuberculosis in Henan is still serious, and the case finding of tuberculosis should be strengthened. Increasing the times of sputum examination from 2 to 3 can increase the rate of case finding.

Adult↗