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At least 865 records · Page 48Linked to original sources
PubMed2026

Establishment of an efficient Agrobacterium-mediated genetic transformation protocol for Saccharum officinarum using Black Cheribon as a model genotype.

Efficient Agrobacterium-mediated transformation (AMT) is vital for the biotechnological improvement of sugarcane (Saccharum spp.). Saccharum officinarum is the main ancestor of all modern cultivars, yet little research has been conducted on its AMT system. In this work, an efficient AMT protocol for S. officinarum was developed, with Black Cheribon as the model genotype owing to its superior tissue culture performance and regeneration capacity. The optimized agro-infection protocol comprised the following main parameters: concentration of acetosyringone (AS) in Agrobacterium culture, concentration of AS for infection, Agrobacterium concentration at OD600 = 0.4, infection time of 30 minutes, vacuum infiltration time of 10 minutes and co-cultivation time of 3 days. To further improve transformation efficiency, 0.5 mg/L thidiazuron and 200 mg/L citric acid were added to the regeneration medium, which enhanced the regeneration of shoots. A modified stage-dependent selection strategy (FlexII) was established by using glufosinate-ammonium at concentrations of 2.0, 1.0, and 0.75 mg/L in the callus proliferation, shoot regeneration, and rooting stages, respectively. This strategy was more successful than the minimum inhibitory concentration-based strategy in S. officinarum transformation. The optimized protocol further boosted the transformation efficiency of Black Cheribon from 1.12% to 7.17%. The resulting transgenic lines were confirmed by PCR amplification of T-DNA regions and immunochromatographic detection of Bar protein expression in primary transformants, respectively. These results provide a sound technical foundation for the functional genomics and biotechnological optimization of S. officinarum germplasm, and may serve as a reference for future transformation studies in other sugarcane germplasm.

Agrobacterium↗
PubMed2004

Targeted disruption of TGF-beta/Smad3 signaling modulates skin fibrosis in a mouse model of scleroderma.

Transforming growth factor-beta (TGF-beta) is a potent stimulus of connective tissue accumulation, and is implicated in the pathogenesis of scleroderma and other fibrotic disorders. Smad3 functions as a key intracellular signal transducer for profibrotic TGF-beta responses in normal skin fibroblasts. The potential role of Smad3 in the pathogenesis of scleroderma was investigated in Smad3-null (Smad3(-/-)) mice using a model of skin fibrosis induced by subcutaneous injections of bleomycin. At early time points, bleomycin-induced macrophage infiltration in the dermis and local TGF-beta production were similar in Smad3(-/-) and wild-type mice. In contrast, at day 28, lesional skin from Smad3(-/-) mice showed attenuated fibrosis, lower synthesis and accumulation of collagen, and reduced collagen gene transcription in situ, compared to wild-type mice. Connective tissue growth factor and alpha-smooth muscle actin expression in lesional skin were also significantly attenuated. Electron microscopy revealed an absence of small diameter collagen fibrils in the dermis from bleomycin-treated Smad3(-/-) mice. Compared to fibroblasts derived from wild-type mice, Smad3(-/-) fibroblasts showed reduced in vitro proliferative and profibrotic responses elicited by TGF-beta. Together, these results indicate that ablation of Smad3 is associated with markedly altered fibroblast regulation in vivo and in vitro, and confers partial protection from bleomycin-induced scleroderma in mice. Reduced fibrosis is due to deregulated fibroblast function, as the inflammatory response induced by bleomycin was similar in wild-type and Smad3(-/-) mice.

Actins↗
PubMed1995

Internal representations of the motor apparatus: implications from generalization in visuomotor learning.

Recent computational studies have proposed that the motor system acquires internal models of kinematic transformations, dynamic transformations, or both by learning. Computationally, internal models can be characterized by 2 extreme representations: structured and tabular (C. G. Atkeson, 1989). Tabular models do not need prior knowledge about the structure of the motor apparatus, but they lack the capability to generalize learned movements. Structured models, on the other hand, can generalize learned movements, but they require an analytical description of the motor apparatus. In investigating humans' capacity to generalize kinematic transformations, we examined which type of representation humans' motor system might use. Results suggest that internal representations are nonstructured and nontabular. Findings may be due to a neural network model with a medium number of neurons and synapses.

Adult↗
PubMed2003

Dysregulation of DNA repair pathways in a transforming growth factor alpha/c-myc transgenic mouse model of accelerated hepatocarcinogenesis.

Previous work from our laboratory has implicated oxidative DNA damage and genetic instability in the etiology of transforming growth factor-alpha (TGFalpha)/c-myc-associated hepatocarcinogenesis. In contrast, oxidative DNA damage was lower in c-myc single-transgenic mice, consistent with less chromosomal damage and with later and more benign tumor formation. We examined whether defects in the DNA repair pathways contribute to the acceleration of liver cancer in TGFalpha/c-myc mice. A cDNA expression array containing 140 known genes and multiplex RT-PCR were used to compare the basal levels of expression of DNA repair genes at the dysplastic stage. Thirty-five percent (8/23) and 43% (10/23) of DNA repair genes were constitutively up-regulated in 10-week-old TGFalpha/c-myc and c-myc transgenic livers, respectively, compared with wild-type controls. The commonly up-regulated genes were OGG1 and NTH1 of base excision repair; ERCC5, RAD23A, and RAD23B of nucleotide excision repair; and RAD50, RAD52, and RAD54 involved in DNA strand break repair. Additional treatment with a peroxisome proliferator, Wy-14,643, known to increase the level of oxidants in the liver, failed to induce a further increase in the expression level of DNA repair enzymes in TGFalpha/c-myc but not in c-myc or wild-type livers. Moreover, expression of several genes, including Ku80, PMS2, and ATM, was decreased in TGFalpha/c-myc livers, suggesting a fault or inefficient activation of the DNA repair pathway upon induction of oxidative stress. Together, the results show that DNA damage response is attenuated in TGFalpha/c-myc mice, creating a condition that may contribute to acceleration of liver cancer in this model.

Animals↗
PubMed1996

Analysis of rhinomanometric data based upon a model of nasal airflow and logarithmic transformation of the data.

Estimation of nasal airflow, flow asymmetry and nasal valve stiffness was performed using anterior rhinomanometry in a group of 12 normal subjects and a group of 12 patients suffering from nasal obstruction. The method, based upon a simplified mathematical model of nasal airflow and utilizing logarithmic transformation of inspiratory pressure and flow data, improved the sensitivity and specificity of rhinomanometry and gave a more comprehensive index of nasal function.

Airway Resistance↗
PubMed1984

Interaction of model discoidal complexes of phosphatidylcholine and apolipoprotein A-I with plasma components. Physical and chemical properties of the transformed complexes.

Conversion of model discoidal complexes of egg yolk phosphatidylcholine and apolipoprotein A-I, upon interaction with a source of lecithin:cholesterol acyltransferase (plasma d greater than or equal to 1.21 g/ml fraction or partially purified enzyme) and with different sources of substrate unesterified cholesterol (LDL, VLDL or cholesterol incorporated into complexes), was investigated by gradient gel electrophoresis, gel filtration, equilibrium density gradient ultracentrifugation, electron microscopy and chemical analysis. When the incubation mixture contained an inhibitor of lecithin:cholesterol acyltransferase, discoidal complexes with mean long dimension of approximately 10.5 +/- 1.9 nm were converted (within 1 h) predominantly to small round particles and were partially depleted of their phospholipid content. Upon electrophoresis the small particles showed peak maxima within the migration intervals of the human plasma ( HDL3b ) gge and ( HDL3c ) gge subpopulations with associated particle size ranges of 7.8-8.2 and 7.2-7.8 nm, respectively. Within 1 h, in the presence of activated enzyme, the complexes were again converted in major part to the small particles. However, further incubation resulted in an apparent single-step conversion to a larger major product with peak maximum occurring within the migration intervals of the ( HDL2a ) gge and the ( HDL3a ) gge subpopulations (particle size ranges 8.8-9.8 and 8.2-8.8 nm, respectively). Formation of an apolar core was indicated by detection of cholesteryl esters in the conversion product. The form in which the substrate unesterified cholesterol was introduced did not markedly influence the size properties of the final conversion product. With VLDL as source of substrate, considerable incorporation of triacylglycerol occurred in company with a lower level of cholesteryl esters, suggesting transfer of these lipids during formation of the apolar core. Incubation of complexes with a partially purified (3000-fold) preparation of lecithin:cholesterol acyltransferase yielded a product similar in properties to that when the d greater than or equal to 1.21 g/ml fraction was used. Our model discoidal complexes and their conversion products exhibit properties very similar to those of potential precursors to HDL as well as of mature HDL particles. Their further investigation shows promise of providing detailed insight into the possible origin and heterogeneity of human plasma HDL.

Acyltransferases↗
PubMed2005

In-line monitoring of hydrate formation during wet granulation using Raman spectroscopy.

Process-induced transformations are very important to control during pharmaceutical manufacturing because they may change the properties of the active pharmaceutical ingredient in the drug product, compromising therapeutic efficacy. One process that may facilitate a process-induced transformation is high-shear wet granulation. In this study, the feasibility of Raman spectroscopy for in-line monitoring of the transformation of theophylline anhydrous to theophylline monohydrate during high-shear wet granulation has been evaluated. The midpoint of conversion occurred 3 min after the binder solution was added. The effects of several processing parameters were also examined, including mixing speed and monohydrate seeding. Mixing speed had the greatest effect on the transformation, where an increase in mixing speed shortened the onset time and increased the rate of transformation. In contrast, seeding with monohydrate or changing the way in which the binder was incorporated into the granules did not affect the transformation profile. The transformation kinetics observed during wet granulation were compared with those generated by a simple model describing the solvent-mediated transformation of theophylline in solution. In conclusion, these studies show that Raman spectroscopy can be used for in-line monitoring of solid-state transformations during wet granulation. In addition, for this particular compound, a simple solvent-mediated transformation model has been shown to be useful for estimating the time scale for hydrate formation during high-shear wet granulation.

Algorithms↗
PubMedDate not supplied

Differential activity of NO synthase inhibitors as chemopreventive agents in a primary rat tracheal epithelial cell transformation system.

A model to study the effectiveness of potential chemopreventive agents that inhibit neoplastic process by different mechanisms has been used to test the efficacy of seven nitric oxide synthase (NOS) inhibitors. Five selective inducible NOS (iNOS) inhibitors: S-methyl isothiourea (S-MITU), S-2-aminoethyl isothiourea (S-2-AEITU), S-ethyl isothiourea (S-EITU), aminoguanidine (AG), 2-amino-4-methyl pyridine (2-AMP), and two non selective general NOS inhibitors: l-N(6)-(1-iminoethyl) lysine (IEL) and N(omega)-nitro-l-arginine (NNLA), were tested for efficacy against a carcinogen, benzo[a]pyrene (B[a]P)-induced primary rat tracheal epithelial (RTE) cell transformation assay. RTE cells were treated with B[a]P alone or with five nontoxic concentrations of an NOS inhibitor and the resulting foci at the end of 30 days were scored for inhibition of transformation. The results indicate that all three isothiourea compounds inhibited B[a]P-induced RTE foci in a dose-dependent manner. S-AEITU was the most effective inhibitor with an IC(50) (the molar concentration that inhibits transformation by 50%) of 9.1 microM and 100% inhibition at the highest dose tested (30 microM). However, both S-EITU and S-MITU showed a maximum percent inhibition of 81% and 100% at 1 mM with an IC(50) of 84 and 110 microM, respectively. 2-AMP did not show any dose-dependent response, but was highly effective (57% inhibition) at an intermediate dose of 30 microM and an IC(50) of 25 microM. Similar to thiourea compounds, AG exhibited good dose-dependent inhibition with a maximum inhibition of 86% at 1 mM. NNLA and IEL were negative in this assay. Based on the IC(50) values, NOS inhibitors were rated for efficacy from high to low as follows: S-2-AEITU<2-AMP<AG<S-MITU<S-EITU. The data from this study identify NOS inhibitors as a novel class of chemopreventive agents that can be developed for lung cancer prevention.

Animals↗
PubMed1980

A model of distributed type associative memory with quantized Hadamard transform.

This paper proposes a new correlation matrix network model of associative memory in brain. Each memorized pattern which consists of binary (+1 or -1) elements is preprocessed by a quantized Hadamard transform to increase selectivity. The association ability of a correlation matrix network model depends on the orthogonality between key patterns by which the corresponding memorized patterns are associatively recalled. In a brain model, however, it is rare that the key patterns are mutually orthogonal since they are memorized patterns themselves. The quantized Hadamard transform, presented in this paper, renders the memorized patterns approximately orthogonal. The model is tested by computer simulation.

Animals↗
PubMed1990

Transforming growth factor-beta stimulates wound healing and modulates extracellular matrix gene expression in pig skin. I. Excisional wound model.

The effect of transforming growth factor-beta 1 (TGF-beta 1) on matrix gene expression has been investigated during the process of wound repair, where the formation of new connective tissue represents a critical step in restoring tissue integrity. Split-thickness excisional wounds in the pig were studied by in situ hybridization in order to obtain subjective findings on the activity and location of cells involved in matrix gene expression after the administration of recombinant TGF-beta 1. Data focus on the stimulatory role of this growth factor in granulation tissue formation, on the enhanced mRNA content of collagen types I and III, fibronectin, TGF-beta 1 itself, and on the reduction in stromelysin mRNA, suggesting that increased matrix formation measured after treatment with TGF-beta 1 is due to fibroplasia regulated by the abundance of mRNAs for several different structural, matrix proteins as well as inhibition of proteolytic phenomena elicited by metalloproteinases. These studies reveal elastin mRNA early in the repair process, and elastin mRNA expression is enhanced by administration of TGF-beta 1. Moreover, we show that TGF-beta 1 was auto-stimulating in wounds, accounting, at least in part, for the persistent effects of single doses of this multipotential cytokine.

Animals↗
PubMed2005

Lung cancer in Mayak workers: interaction of smoking and plutonium exposure.

Lung cancer mortality among 5,058 male workers of the Mayak Production Association has been analyzed with emphasis on the interaction of smoking and radiation exposure by using the two-step clonal expansion (TSCE) model of carcinogenesis. The cohort consists of all Mayak workers with known smoking status, who were employed in the period 1948-1972, and who either had the plutonium concentration in urine measured or who worked in the reactors, where plutonium exposure was negligible. Those who died during the first two years after the first urine sampling were excluded. The follow-up extended until the end of 1998. During this time, 2,176 workers died, including 244 lung cancer cases. Mayak workers were exposed to external (gamma and neutron) radiation, and in the radiochemical and plutonium plants to plutonium. In the preferred TSCE model, internal radiation and smoking act on the clonal expansion of pre-carcinogenic clones. Assuming a plutonium radiation weighting factor of 20, the excess relative risk per lung dose was estimated to be 0.11 (95% CI: 0.08; 0.17) Sv(-1). Most of the lung cancer deaths are found to be due to smoking. The second main factor is the interaction of smoking and internal radiation. The model is sub-multiplicative in relative risks due to smoking and radiation. In a multiplicative version of the TSCE model, internal radiation acts on initiation and transformation rates. This model version agrees with conventional epidemiological risk models, because it also suggests a higher risk estimate than the preferred TSCE model. However, it fits the data less well than the preferred model.

Biophysical Phenomena↗
PubMed2005

Synergy: a framework for leadership development and transformation.

The Synergy Model has been adopted as an organizing framework for nursing practice, education, and leadership at Clarian Health Partners, Inc. of Indiana. This article describes the evolution of educational programs at Clarian, in concert with the implementation of the Synergy Model. Philosophical and operational changes in staff orientation, professional development, and management development are described.

Career Mobility↗
PubMed2004

Modeling the effect of algal dynamics on arsenic speciation in Lake Biwa.

Algae reduce and methylate arsenate and the end product of the reaction is correlated to their growth rate. At slow growth rates, dimethylarsinate (DMA) is produced, and at fast growth rates arsenite (As(III)) is produced. Previous work has linked this phenomenon to the phosphorus luxury uptake mechanism of algae, and a model was developed for the process (Hellweger et al. Limnol. Oceanogr. 2003, 48, 2275). This paper presents the integration of that process model for arsenic transformation by algae into a full ecological model and application to Lake Biwa, Japan. The model application allows for a quantitative analysis of the field data, consistent with the process model and the ecological dynamics of the lake. The newly developed ecological model includes a variable phytoplankton composition, which is needed to simulate luxury uptake. This is in contrast to most existing ecological models, which typically assume a fixed "Redfield" composition. The model adequately reproduces the observed ecology of Lake Biwa, including the rapid uptake of phosphate by phytoplankton without immediate growth (luxury uptake) following lake overturn. The model also reproduces the observed arsenic speciation, including the gradual appearance of DMA during the summer and peaks in As(III) concentration at the onset of spring and fall algal blooms.

Arsenic↗
PubMed2005

Integrated numerical model of nitrogen transportation, absorption and transformation by two-dimension in soil-crop system.

A series of simulation experiments of nitrogen transportation, absorption and transformation were conducted, and the different cropping patterns of winter wheat and wastewater irrigation plans were taken into consideration. Based on the experiments, an integrated model of crop growth, roots distribution, water and nitrogen absorption by roots, water and nitrogen movement and transformation in soil-crop system by two-dimension was developed. Parameters and boundary conditions were identified and an effective computing method for optimizing watering and wastewater irrigating plans was provided.

Crops, Agricultural↗
PubMed1998

Modeling and superposition of multiple protein structures using affine transformations: analysis of the globins.

A novel approach for analyzing multiple protein structures is presented. A family of related protein structures may be characterized by an affine model, obtained by applying transformation matrices that permit both rotation and shear. The affine model and transformation matrices can be computed efficiently using a single eigen-decomposition. A novel method for finding correspondences is also introduced. This method matches curvatures along the protein backbone. The algorithm is applied to analyze a set of seven globin structures. Our method identifies 100 corresponding landmarks across all seven structures. Results show that most helices in globins can be identified by high curvature, with the exception of the C and D helices. Analysis of the superposition reveals that globins are most strongly conserved structurally in the mid-regions of the E and G helices.

Algorithms↗