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PubMed2026

The effect of tDCS on emotion-related risk-taking behavior and delay discounting in adults with ADHD.

INTRODUCTION: Adults with Attention Deficit Hyperactivity Disorder (ADHD) often engage in risky behaviors due to impaired decision-making processes. This study aims to investigate the effects of transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC) on emotion-related risk-taking behavior and delay discounting in adults with ADHD. METHODS: Thirty adults with ADHD underwent three tDCS conditions, administered in a randomized order with at least one week between sessions: (1) left dlPFC anode/right vmPFC cathode, (2) left dlPFC cathode/right vmPFC anode, and (3) sham stimulation. In each session, participants completed the Delay Discounting Task (DDT) and the Modified Balloon Analogue Risk Task (mBART) under three emotional conditions (neutral, positive, and negative) which were induced using emotionally congruent photographs and sounds. Galvanic skin responses (GSR) were also recorded. In the DDT, both area under the curve (AUC) values and log-transformed discounting rates (log k) were calculated for small, medium, and large reward magnitudes (RM). Exploratory electric field modeling was also performed to characterize current distribution. RESULTS: The findings demonstrated task-specific effects of tDCS on decision-making. Although no overall tDCS effect was observed on DDT performance, significant tDCS × RM interactions emerged, particularly for smaller rewards. In contrast, exploratory analyses suggested that tDCS affected all mBART scores. Emotional condition did not influence consistently behavioral performance in either task, whereas both emotional stimulation and tDCS significantly affected GSR responses. However, exploratory electric field modeling indicated a broad prefrontal current distribution extending beyond the intended cortical targets. CONCLUSIONS: These findings suggest preliminary evidence that prefrontal tDCS can influence risk-related decision-making and autonomic responses in adults with ADHD. However, its effects on delay discounting appear to be context-dependent and limited to specific RMs. Future studies combining neuroimaging with individualized electric field modeling are needed to clarify the neural mechanisms underlying the observed effects of tDCS and to optimize stimulation protocols in adults with ADHD.

Humans↗
PubMed2004

Mathematical models of diffusion-constrained polymerase chain reactions: basis of high-throughput nucleic acid assays and simple self-organizing systems.

DNA templates amplified by polymerase chain reaction in thin polyacrylamide gels form diffusion-constrained amplicons called "polonies" (polymerase colonies) that have been used to phase DNA haplotypes over long distances, to analyse RNA splice variants, and to assay other phenomena of biological interest. We present two sets of mathematical models, one for single polony growth (SPGM) and one for two polony interaction (TPIM), that will be used to optimize polony technology. The models provide detailed predictions of polony yield, concentration profiles, growth of isolated polonies, and the interaction of neighboring polonies. The TPIM explains an experimental observation that nearby polonies deform against each other rather than interpenetrate, an effect important for optimizing polony protocols. However, the TPIM also predicts that polonies may invade each other with a complex geometry when sufficiently close. Polonies are also of interest as simple abiotic systems that exhibit lifelike properties of self-organization, growth, and development, and the models may also apply to biological phenomena involving propagation through tethering and diffusion. Our polony modeling software is available at our web site.

Algorithms↗
PubMed2006

Comparison of RNA extraction methods for the detection of porcine reproductive and respiratory syndrome virus from boar semen.

To detect Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in semen, various RNA extraction techniques have been utilized for RT-PCR, but rarely compared, to determine an optimized extraction protocol. Due to the viscosity, non-homogeneity, high cellularity and large volume of boar semen produced, difficulties can be encountered in obtaining RNA from the seminal cell fraction. This study compared six RNA extractions, five which used a commercially available kit (RNeasy, Qiagen Inc.) for use on highly cellular samples and a traditional phenol/chloroform procedure. All extractions were compared on serially diluted PRRSV "spiked" seminal cell fractions. The two methods resulting in recovery of the highest amount of RNA, which included a Qiashredder (Qiagen Inc.) (protocol 1) or cell lysis/centrifugation technique (protocol 3) preceding the RNeasy procedure were then compared using naturally infected semen samples from experimentally infected boars. Both protocols detected similar amounts of virus in "spiked" samples, but protocol 1 detected eight additional PRRSV-positive semen samples in naturally infected semen. This study demonstrated that semen "spiked" with PRRSV (cell-free virus) may not be representative of naturally infected semen samples (cell associated virus) for comparing extraction protocols, but did identify a useful extraction technique for boar semen.

Animals↗
PubMed2006

Prevalence of microplastics in Singapore's coastal marine environment.

Microplastics have been recently identified as marine pollutants of significant concern due to their persistence, ubiquity and potential to act as vectors for the transfer and exposure of persistent organic pollutants to marine organisms. This study documents, for the first time, the presence and abundance of microplastics (>1.6 microm) in Singapore's coastal environment. An optimized sampling protocol for the collection and analysis of microplastics was developed, and beach sediments and seawater (surface microlayer and subsurface layer) samples were collected from nine different locations around the coastline. Low density microplastics were separated from sediments by flotation and polymer types were identified using Fourier transform infrared (FTIR) spectrometry. Synthetic polymer microplastics identified in beach sediments included polyethylene, polypropylene, polystyrene, nylon, polyvinyl alcohol and acrylonitrile butadiene styrene. Microplastics were detected in samples from four out of seven beach environments, with the greatest quantity found in sediments from two popular beaches in the eastern part of Singapore. Polyethylene, polypropylene and polystyrene microplastics were also found in the surface microlayer (50-60 microm) and subsurface layer (1m) of coastal waters. The presence of microplastics in sediments and seawater is likely due to on-going waste disposal practices from industries and recreational activities, and discharge from shipping.

Bathing Beaches↗
PubMed2004

A simple method for differential isolation of freely dispersed and particle-associated peat microorganisms.

Differential isolation of physiologically and ecologically diverse microbial groups facilitates evaluation of their activities in the environment. Here we describe a new method for differential isolation of freely dispersed and particle-associated peat microorganisms. The method is based on sequential elution of peat. Two types of natural peat, "young" sphagnum peat and "old" reed-based peat that have significantly different molecular composition as revealed by solid-state 13C NMR, were used for the method development. Various combinations of elution parameters (pH values, surfactant concentration, and sonication) were tested. Protein yield, CFU counts, 16S rDNA gene sequence, and T-RFLP analyses were used as criteria for evaluating the effectiveness of the elution protocols. The optimal method consisted of sequential elutions with (i) pH 6.2, 0.1 M potassium phosphate buffer, (ii) the same buffer amended with 0.01% of Tween 80, and (iii) treatment (ii) amended with sonication for 2 min. This method allowed differential isolation of freely dispersed and particle-associated microorganisms with (i) highest yield, (ii) highest diversity within the each microbial fraction, and (iii) best discrimination between the freely dispersed and particle-associated microbial communities. The method was applied for characterization of peat microbial communities and revealed different taxonomic composition and similar spatial organization of sphagnum and reed-sage peat microorganisms.

Arthrobacter↗
PubMed2005

Ex vivo magnetic resonance imaging of rat spinal cord at 9.4 T.

The magnetic resonance (MR) properties of the rat spinal cord were characterized at the T9 level with ex vivo experiments performed at 9.4 T. The inherent endogenous contrast parameters, proton density (PD), longitudinal and transverse relaxation times T1 and T2, and magnetization transfer ratio (MTR) were measured separately for the grey matter (GM) and white matter (WM). Analysis of the measurements indicated that these tissues have statistically different proton densities with means PD(GM)=54.8+/-2.5% versus PD(WM)=45.2+/-2.4%, and different T1 values with means T1GM=2.28+/-0.23 s versus T1WM=1.97+/-0.21 s. The corresponding values for T2 were T2GM=31.8+/-4.9 ms versus T2WM=29.5+/-4.9 ms, and the difference was insignificant. The difference between MTR(GM)=31.2+/-6.1% and MTR(WM)=33.1+/-5.9% was also insignificant. These results collectively suggest that PD and T1 are the two most important parameters that determine the observed contrast on spinal cord images acquired at 9.4 T. Therefore, in MR imaging studies of spinal cord at this field strength, these parameters need to be considered not only in optimizing the protocols but also in signal enhancement strategies involving exogenous contrast agents.

Animals↗
PubMed2004

Optimizing the experimental design for ankle dorsiflexion fMRI.

Compared to motor studies of the upper limb, few experiments have sought a relationship between blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) sensorimotor signals and the resulting lower limb output. In Experiment 1, using an fMRI simulator system, we determined the optimized experimental protocol based on two design types and four behavioral movement types during ankle dorsiflexion. Experiment 2 involved testing the BOLD sensitivity at 1.5 T during ankle movements. Subjects performed large- and small-amplitude dorsiflexion movement types using an event-related design, with the intent of contrasting spatial and temporal features of the BOLD signal. In both experiments, the subject's behavior was guided by visual biofeedback of their ankle flexion angle, using an MR-compatible fiberoptic tape. From Experiment 1, we found electromyography (EMG) difference voltage ratio of approximately 2:1 for large (40 degrees ) and small (15 degrees ) dorsiflexion, 0.13 mV and 0.07 mV, respectively. In Experimental 2, we found the peak BOLD % signal changes of 1.04% and 0.89%, for large (40 degrees ) and small (15 degrees ) dorsiflexion, respectively. In addition, graded dorsiflexion produced graded BOLD signals in the primary sensorimotor and supplementary motor areas in 10 of 12 healthy young subjects, attesting to the feasibility of lower-limb fMRI at 1.5 T. This study provides insight into the cortical network involved in dorsiflexion using an experimental paradigm that is likely to translate effectively to hemiparetic stroke subjects.

Adult↗
PubMed2005

Using voxel-based morphometry to map the structural changes associated with rapid conversion in MCI: a longitudinal MRI study.

Capturing the dynamics of gray matter (GM) atrophy in relation to the conversion from mild cognitive impairment (MCI) to clinically probable Alzheimer's disease (AD) would be of considerable interest. In this prospective study we have used a novel longitudinal voxel-based method to map the progression of GM loss in MCI patients over time and compared converters to non-converters. Eighteen amnestic MCI patients were followed-up for a predefined fixed period of 18 months and conversion was judged according to NINCDS-ADRDA criteria for probable AD. Each patient underwent a high-resolution T1-weighted volume MRI scan both at entry in the study and 18 months later. We used an optimal VBM protocol to compare baseline imaging data of converters to those of non-converters. Moreover, to map GM loss from baseline to follow-up assessment, we used a modified voxel-based morphometry (VBM) procedure specially designed for longitudinal studies. At the end of the follow-up period, seven patients had converted to probable AD. Areas of lower baseline GM value in converters mainly included the hippocampus, parahippocampal cortex, and lingual and fusiform gyri. Regions of significant GM loss over the 18-month follow-up period common to both converters and non-converters included the temporal neocortex, parahippocampal cortex, orbitofrontal and inferior parietal areas, and the left thalamus. However, there was significantly greater GM loss in converters relative to non-converters in the hippocampal area, inferior and middle temporal gyrus, posterior cingulate, and precuneus. This accelerated atrophy may result from both neurofibrillary tangles accumulation and parallel pathological processes such as functional alteration in the posterior cingulate. The ability to longitudinally assess GM changes in MCI offers new perspectives to better understand the pathological processes underlying AD and to monitor the effects of treatment on brain structure.

Aged↗
PubMed2006

Age-related water diffusion changes in human brain: a voxel-based approach.

The aim of the present study is to investigate age-related changes in water self-diffusion in cerebral white matter by analysing diffusion-weighted MRI from a sample of 54 healthy volunteers. A voxel-based analysis of the relative anisotropy and the apparent diffusion coefficients was performed by applying an optimized normalization protocol. Linear regression analysis revealed significant correlations with age in the corpus callosum, prefrontal regions, the internal capsule, the hippocampal complex, and the putamen. However, in other regions, such as those surrounding the ventricles, the insula, or the inferior frontal plane, significant correlations between age and ADC were observed, presumably as a result of morphological age-related variations. A mask procedure was carried out in order to distinguish between morphological involvement and real age-related white matter changes. Our results indicate that in interpreting the changes in each significant region it is necessary to proceed with precaution because the voxel-based statistical analysis might yield a mixture of two effects: (i) morphological changes that remain after the normalization procedure and (ii) actual diffusivity parameter changes. Anatomically defined regions of interest may help us to minimize morphologic involvement and draw comparisons with findings previously published.

Adult↗
PubMed2006

Desmoid tumors and current status of management.

Desmoid tumors, also known as aggressive fibromatosis, are rare fibroblastic tumors that exhibit a wide range of local aggressiveness, from largely indolent to locally destructive. Understanding of the pathogenesis and the great heterogeneity in the natural history of desmoid tumors is invaluable to the development of therapeutic strategies. The optimal treatment protocol has not yet been established and, in many cases, a multidisciplinary approach including surgery, chemotherapy, and radiation therapy has been employed. The rarity of cases in even major tumor centers has traditionally limited the ability to study this disease. Several novel pharmacologic and biologic treatment approaches are actively being developed, although long-term follow-up is needed for their substantiation.

Adolescent↗
PubMed2004

[Gene therapy of restenosis and atherosclerosis: hopes and facts].

Stents are the main technique of coronary revascularization in France and western countries. However, a better understanding of the pathophysiology of in-stent restenosis and the well-recognized roles played by inflammation and cell proliferation led to the development of drug-eluting stents, which have nearly eliminated the risk of restenosis. In this context, the success of gene therapy will depend on our ability to simplify and optimize current protocols of arterial gene transfer. For the time being, arterial gene therapy remains a powerful tool for deciphering the complex pathophysiology of restenosis and will certainly have far-reaching implications in the fields of vascular biology and therapeutics.

Adenoviridae↗
PubMed2005

Multidrug transporter MexB of Pseudomonas aeruginosa: overexpression, purification, and initial structural characterization.

Structural and functional characterization of the multidrug transporter, MexB, of Pseudomonas aeruginosa is significantly restricted due to a low yield of approximately 0.1 mg/L of culture from natural sources. To facilitate structural studies of this medically important transporter protein, we developed a large-scale system for expression of the genetically engineered recombinant, MexB, in the Escherichia coli cell. Using the system, the eventual yield of MexB attained was about 10mg/L of culture. The optimized purification protocol in the presence of dodecyl beta-D-maltoside allowed isolation of highly homogeneous MexB. The oligomeric state of the protein in detergent solution has been characterized to verify that the native state of the purified protein has been preserved. The molecular mass of the protein-detergent complex was found to be 380-450kDa. The MexB-dodecyl beta-d-maltoside mass ratio was determined to be 1.8 +/- 0.05. Taking into account the monomeric MexB molecular mass deduced from its amino acid sequence (112.8 kDa), we concluded that the purified MexB exists as the homotrimer in the surfactant solution. Circular dichroism analysis of MexB showed dominance of the alpha-helix structures. High yield, homogeneity, and stability of MexB position it as a good candidate for structural and functional characterization.

Bacterial Outer Membrane Proteins↗
PubMed2026

Establishment of a cBSA-mediated miRNA delivery system in Camellia sinensis and functional validation of the Cs-miR163/CsSK1 module in cold stress response.

Cold stress severely limits tea (Camellia sinensis) yield and quality. MicroRNAs (miRNAs) are key post-transcriptional regulators of plant cold responses; however, in vivo functional validation in tea plants is hindered by the lack of efficient genetic transformation and nucleic acid delivery systems. In this study, a cationized bovine serum albumin (cBSA)-mediated miRNA delivery system was established in tea plants. The cold-responsive miRNA Cs-miR163 and its target gene CsSK1 (a negative regulator of cold tolerance) were used as a model. Direct cleavage of CsSK1 mRNA by Cs-miR163 was confirmed by 5' RLM-RACE and GUS transient expression assays, and enhanced cold tolerance was demonstrated in Arabidopsis overexpression lines. The cBSA preparation protocol was optimized, yielding stable cBSA/miRNA complexes with high protective capacity across temperatures of 15-35 °C and pH 4.5-7.2. Delivery parameters were systematically evaluated; optimal conditions were determined as 2 mg/mL cBSA with 10 nM miRNA and solution uptake into 3-cm cuttings for 5 days, enhancing miRNA delivery efficiency by approximately 48-fold. Transmission electron microscopy provided direct ultrastructural evidence that cBSA/miRNA nanocomplexes are internalized into tea plant cells via adsorptive-mediated endocytosis involving electrostatic membrane adsorption, membrane invagination, and cytoplasmic release. Under optimized conditions, cBSA-mediated delivery of Cs-miR163 silenced CsSK1 expression by approximately 72%, reduced relative electrolyte leakage and ROS accumulation, and markedly enhanced cold tolerance. The regulatory role of the Cs-miR163/CsSK1 module was clarified, and the established system provides a promising strategy for functional genomics in woody plants that warrants further testing in additional species and tissues.

Camellia sinensis↗
PubMed2005

Electroporation-mediated transformation of Aeromonas hydrophila.

A strain of Aeromonas hydrophila producing copolyesters of 3-hydroxybutyrate and 3-hydroxyhexanoate, abbreviated as PHBHHx, was successfully transformed by electroporation. The plasmid used was a broad host range plasmid pBBR1MCS. Electroporation conditions were varied systemically to develop an electroporation protocol. The optimal yield of transformant was approximately 4x10(2) CFU/microg DNA at 12.5 kV/cm and 1000 Omega, resulting in a time constant of approximately 5 ms. The A. hydrophila transformants expressed plasmid-encoded resistance to chloromphenicol. Plasmid DNA in the A. hydrophila transformant was stably maintained. This is the first report of transformation of bacteria A. hydrophila.

3-Hydroxybutyric Acid↗
PubMed2004

Voxel-based morphometry in adolescents with bipolar disorder: first results.

Bipolar disorder is an increasingly recognized cause of significant morbidity in the pediatric age group. However, there is still a large degree of uncertainty regarding the underlying neurobiological deficits. In this preliminary study, we performed automated volumetric studies and whole-brain voxel-based morphometry (VBM) on gray matter. Imaging data from 10 adolescents with bipolar disorder were compared with data from 52 age- and gender-matched healthy controls. Previously defined brain parcellations and optimized VBM protocols were used, based on custom-made pediatric reference data. An additional, exploratory whole-brain comparison was also implemented. The volumetric region-of-interest study revealed significantly greater gray matter volume in central gray matter structures bilaterally (including the basal ganglia and the thalamus) and the left temporal lobe in the bipolar group. VBM confirmed bilaterally larger basal ganglia. Localized gray matter deficits in bipolar subjects were found in the medial temporal lobe, orbito-frontal cortex, and the anterior cingulate, confirming and extending earlier studies.

Adolescent↗
PubMed2005

Multidetector row CT of the liver.

CT has always played a major role in the imaging of the liver despite continuous challenge by ultrasound and MR imaging. Introduction of multidetector row CT technology has helped CT to excel in its already established indications and has expanded its capabilities by adding new clinical indications, such as CT angiography or liver perfusion. This article discusses the advantages of multidetector row CT scanners in liver imaging, examines the guidelines to improve image quality by optimizing scanning protocols and contrast administration strategies, and reviews the current and potential clinical applications.

Angiography↗
PubMed2005

Characterization of MNAR expression.

We have previously demonstrated that modulator of nongenomic action of estrogen receptor (MNAR) integrates action of estrogen receptor alpha (ERalpha), and potentially some other nuclear receptors (NRs), in regulation of Src/Ras/Raf/mitogen-activated protein kinase (MAPK) signaling pathway. MNAR is a scaffolding protein that contains 10 LXXLL type motifs that can interact with NRs and 3 PXXP type motifs that can bind to SH3 domains present in kinases and other signaling molecules. Formation of ER-MNAR-cSrc complex leads to activation of Src and downstream Ras/Raf/MAPK pathway. The goal for this study was to compare MNAR expression in various cell lines, to optimize methods that can be used to manipulate its expression and to evaluate MNAR cellular distribution. We found that MNAR is differentially expressed. The highest levels of its expression were found in fast proliferating cells, such as breast adenocarcinoma (MCF-7)-, T cell lymphoma (Jurkat)-, prostate carcinoma (LNCaP)- and osteosarcoma (SaOS2)-derived cell lines. MNAR was undetectable in African green monkey kidney cells (COS-7) and Chinese hamster ovary cells (CHO-K1). We established and optimized a protocol to knockdown MNAR using siRNA and to overexpress it in MCF-7 cells. Exogenously expressed MNAR was found in both cytoplasmic and nuclear fractions, the majority of MNAR, however, was found in the cytoplasmic fraction. Presence of MNAR in the cell nucleus indicates that it may play a role in regulation of gene expression.

Animals↗
PubMed2025

Cell-type-specific DNA methylation dynamics in the prenatal and postnatal human cortex.

The human cortex undergoes extensive epigenetic remodeling during development, although the precise temporal and cell-type-specific dynamics of DNA methylation remain incompletely understood. In this study, we profiled genome-wide DNA methylation across human cortex tissue from donors aged 6 post-conception weeks to 108 years of age. We observed widespread, developmentally regulated changes in DNA methylation, with pronounced shifts occurring during early- and mid-gestation that were distinct from age-associated modifications in the postnatal cortex. Using fluorescence-activated nuclei sorting, we optimized a protocol for the isolation of SATB2-positive neuronal nuclei, enabling the identification of cell-type-specific DNA methylation trajectories in the developing cortex. Developmentally dynamic DNA methylation sites were significantly enriched near genes implicated in autism and schizophrenia, supporting a role for epigenetic dysregulation in neurodevelopmental conditions. Our findings underscore the prenatal period as a critical window of epigenomic plasticity in the brain with important implications for understanding the genetic basis of neurodevelopmental phenotypes.

Humans↗