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PubMed2000

Adaptive will: the evolution of attention deficit disorder.

The increasing prevalence of attention-deficit disorder among American school children was a source of significant controversy in the 1990s. This paper looks at the social and historical contexts in which ADD evolved in order to understand its emergence as a coherent and widespread entity. Changes in expert models of child behavior interacted with the formation of new identities around disability to shape a milieu in which the disorder could thrive. The pattern of affect control, of what must and what must not be restrained, regulated, and transformed, is certainly not the same in this stage as in the preceding one of court aristocracy. In keeping with its different interdependencies, bourgeois society applies stronger restrictions to certain impulses, while in the case of others aristocratic restrictions are simply continued and transformed to suit the changed situation (Elias, 1994, p. 125).

Attention Deficit Disorder with Hyperactivity↗
PubMed1996

Differential Taxol-dependent arrest of transformed and nontransformed cells in the G1 phase of the cell cycle, and specific-related mortality of transformed cells.

Taxol (paclitaxel) induces a microtubule hyperassembled state, and effectively blocks cells in mitosis. Here we report that Taxol also induces a stable late-G1 block in nontransformed REF-52 and WI-38 mammalian fibroblast cells, but not in T antigen-transformed cells of the same parental lineage. G1 arrest is characterized by partially dephosphorylated pRb, and inactive cdk2 kinase. Nontransformed cells recover normally from Taxol arrest. In contrast, T antigen transformed cells continue inappropriately past both G1 and G2-M in the presence of Taxol, and undergo a rapid death upon release. These results demonstrate a microtubule sensitive step in G1 regulation of nontransformed fibroblast cells. Also, Taxol selectively induces death of transformed cells, possibly because they slip the Taxol-dependent G1 arrest, as well as G2/M arrest, which are both specific to nontransformed cells.

Animals↗
PubMed2004

Determination of chlorogenic acid in plant samples by using near-infrared spectrum with wavelet transform preprocessing.

By theoretical analysis, it is found that wavelet transform (WT) with a wavelet function can be regarded as a smoothing and a differentiation process, and that the order of differentiation is determined by the vanishing moment, which is an important property of a wavelet function. Therefore, a method based on the continuous wavelet transform (CWT) for removing the background in the near-infrared (NIR) spectrum is proposed, and it is used in the determination of the chlorogenic acid in plant samples as a preprocessing tool for partial least square (PLS) modeling. It is shown that the benefit of the proposed method lies not only in its performance to improve the quality of PLS model and the prediction precision, but also in its simplicity and practicability. It may become a convenient and efficient tool for preprocessing NIR spectral data sets in multivariate calibration.

Algorithms↗
PubMed2000

Spike-and-wave discharges of absence seizures as a transformation of sleep spindles: the continuing development of a hypothesis.

OBJECTIVES: This review aims to offer a critical account of recent scientific developments relevant to the hypothesis which Pierre Gloor proposed in the 1970s for the generation of spike and wave discharges (SWDs) of primary generalized absence seizures. RESULTS: According to this hypothesis SWDs develop in the same circuits, which normally generate sleep spindles, by an initially cortical transformation of one every two or more spindle waves to a 'spike' component of SWDs, while the next one or more spindle waves are eliminated and replaced by a slow negative wave. This hypothesis was based on experiments in feline generalized penicillin epilepsy showing the possibility of transition from spindles to SWDs, when cortical neurons become hyper-responsive to thalamocortical volleys, which normally induce spindles, and thus engage feedback cortical inhibition, rebound excitation, recurrent intracortical dissemination of excitation during the 'spike' and strong excitation of thalamus for further augmentation of a brain wide synchronous oscillation. In the 1980s, electrophysiological studies in vitro and in vivo revealed the basic features of spindle rhythm generation by neurons in nucleus reticularis thalami and thalamocortical-corticothalamic oscillatory reverberations. CONCLUSIONS: In the light of this knowledge, experimental studies in several genetic and pharmacological animal models of absence seizures, clinical observations and theoretical studies in computer models have considered, tested, modified and challenged this hypothesis. It may still be found useful in the era of dynamic digital EEG analysis of SWDs and its current sources.

Animals↗
PubMed1986

Comparative analysis of infection and transformation of lymphocytes from African buffalo and Boran cattle with Theileria parva subsp. parva and T. parva subsp. lawrencei.

This study compared infection and transformation of peripheral blood mononuclear cells (PBM) of Boran cattle and African buffalo in vitro to determine whether differences occurred which could account for the greater susceptibility of Boran cattle to infection with Theileria parva subsp. parva and T. parva subsp. lawrencei. PBM from buffalo and cattle had a similar percentage of cells which bound T. parva subsp. parva sporozoites (24 to 34%) and in which schizonts developed during the first week after infection (18 to 23%). Using a limiting dilution culture system, it was established, however, that a significantly higher proportion of cattle PBM transformed into continuously replicating cell lines after infection with T. parva subsp. parva than did buffalo PBM. The evidence suggests that the low capacity of T. parva subsp. parva to establish infections in buffalo compared with cattle is related to the lower frequency of buffalo cells which undergo transformation. With T. parva subsp. lawrencei, however, the frequency of transformation of buffalo PBM was higher than that for cattle PBM. The frequency of cells transformed by T. parva subsp. lawrencei, therefore, cannot account for the greater resistance of buffalo to infections with T. parva subsp. lawrencei. Buffalo must have other mechanisms, either innate or acquired, which control infection with T. parva subsp. lawrencei more efficiently than in cattle.

Animals↗
PubMed1986

Transformation of diploid human fibroblasts by DNA transfection with the v-sis oncogene.

The simian sarcoma virus (SSV) oncogene (v-sis) has a high degree of homology to the cellular gene coding for the B peptide of human platelet-derived growth factor (PDGF), a potent fibroblast mitogen. The cellular homolog of v-sis is activated in some mesenchymal human tumors and cell lines derived from them. To determine the phenotype produced by v-sis in diploid human fibroblasts, we constructed plasmids containing the SSV provirus and drug-resistance markers and transfected them into early-passage human cells. Fibroblasts that had integrated the plasmid were selected for drug resistance and shown to contain and express the v-sis oncogene by DNA and RNA hybridization. The v-sis-expressing cells grew to higher saturation densities than control cells transfected with the vector plasmid alone and formed large, well defined foci. This allowed selection of transfectants directly for focus formation. The v-sis transformed cells continued to grow well in the absence of serum, whereas age-matched, vector-transfected control cells ceased replicating under these conditions so that the final difference in density between the two populations was tenfold. Incorporation of thymidine in serum-free medium by the v-sis-transformed cells was independent of exogenous PDGF. In contrast, PDGF increased thymidine incorporation in such medium by the control cells to the level found in the v-sis-transformed cells with or without added PDGF. These results suggest that expression of the v-sis oncogene in diploid human fibroblasts causes sufficient endogenous synthesis of the B chain of PDGF to allow transformants to grow to abnormally high cell densities. When individual v-sis-transformed cells were grown on a background of normal cells, this higher cell density at confluence could be visualized as a focus.

Cell Count↗
PubMed2005

An adaptive detector of genioglossus EMG reflex using Berkner transform for time latency measurement in OSA pathophysiological studies.

To investigate obstructive sleep apnea syndrome mechanisms, we developed a device to measure the surface electromyogram (EMG) time latency reflex of the genioglossus muscle stimulated by time and amplitude calibrated negative pharyngeal pressure drops. The reflex signals were found to be disturbed by transient signals that generate false alarms. Thus, to reduce false alarm occurrences we designed an adaptive multiscale method. Continuous wavelet transform (CWT) is widely used in biomedical signal event detection processes. The Berkner transform is an approximation of a CWT that is based on a hierarchical scheme similar to discrete wavelet transform. We used the Berkner transform to build a multiscale detector because it offers the possibility of maxima coefficients linkage that leads to good accuracy in reflex onset localization. As a contribution to this novel approach we used a reconstruction formula to develop an adaptive method for scale range determination in our surface EMG reflex detector. Finally, we characterized our detector in terms of accuracy and robustness, first on synthesized signals and second, on signals acquired on apneic patients and healthy subjects. Preliminary results showed a significant difference (p < 0.01) between the two populations regarding the genioglossus muscle mean latency time. These physiological findings may partly explain why the upper airway protective reflex occurring when a negative pressure is applied to the upper airway is ineffective in OSA patients, leading to pharyngeal collapse.

Algorithms↗
PubMed1985

Purine nucleoside phosphorylase synthesis and turnover in human lymphoid cells.

We have studied the turnover and synthesis of purine nucleoside phosphorylase by using a polyclonal rabbit antiserum to this protein. The turnover of purine nucleoside phosphorylase was studied in the B lymphoblast cell, WI-L2, by specific immunoprecipitation of [3H]leucine-labeled proteins. The half-lives for total protein and purine nucleoside phosphorylase were 14.5 and 14.1 hr, respectively. For cells cultured in the presence of inosine the half-life of purine nucleoside phosphorylase was reduced to 11.2 hr. The synthesis of purine nucleoside phosphorylase was analyzed during phytohemagglutinin-stimulated T cell transformation by pulse labeling cells with [35S]methionine. Purine nucleoside phosphorylase synthesis increased greater than 10-fold during the first 12 hr of transformation and continued to a maximum of 30-fold. The relative rate of purine nucleoside phosphorylase labeled to total proteins was 0.04% in unstimulated T cells and increased to 0.18% 12 hr after stimulation. These studies identify some preferential synthesis of purine nucleoside phosphorylase during the early stages of T cell transformation.

B-Lymphocytes↗
PubMed2006

[Continuously modeling research on the transfer and transform processes of phosphorus in Heihe River watershed].

Taking supply water source of Xi'an city as an example, by the help of Matlab software, using fill and yield model, the Inverse-Gauss flow concentration model, runoff-sediment relation model and Viney model, the transfer and transform processes of phosphorus from 1981 to 1990 were modeled continuously. Phosphorus pollution loads of Heihe River were also estimated. The result shows that the continuous modeling result accorded with the generic law of phosphorus loss. The relative error between modeling result and monitor interpolation result was not more than +/-30%. So the modeling method proposed in this paper could be used to model continuously the transfer and transform processes of phosphorus in Heihe river watershed. This study was only primary attempt to non-point source pollution continous model, therefore, the modeling method needed to be improved and perfected further.

China↗
PubMed2000

Telomerase allows the immortalization of T antigen-positive DMD myoblasts: a new source of cells for gene transfer application.

The limited proliferative capacity of DMD myoblasts severely limits their ability to be genetically modified and used for myoblast transplantation. Transformation by SV40 large T antigen (Tag) delays senescence of mouse and human myoblasts but fails to immortalize these cells. The cells ceased to proliferate and entered into crisis. Reconstitution of telomerase activity has been shown sufficient to enable different types of transformed cells to escape crisis. DMD myoblasts, previously transformed by Tag, were therefore infected with a telomerase retrovirus. The expression of telomerase was sufficient to allow DMD-Tag myoblasts to escape crisis. The telomerase-positive transformed myoblasts continued to divide for more than 55 doublings while Tag myoblasts stopped proliferating after 35 doublings. These cells are able to fuse and to differentiate normally. The average telomere length of these telomerase-positive DMD-Tag myoblasts seems to continue to elongate. Thus, transiently genetically modified myoblasts could constitute an important pool of DMD myoblasts for autologous transplantation in DMD patients.

Animals↗
PubMed1999

The use of the wavelet transform to describe embolic signals.

A number of methods to detect cerebral emboli and differentiate them from artefacts using Doppler ultrasound have been described in the literature. In most, Fourier transform-based (FT) spectral analysis has been used. The FT is not ideally suited to analysis of short-duration embolic signals due to an inherent trade-off between temporal and frequency resolution. An alternative approach that might be expected to describe embolic signals well is the wavelet transform. Wavelets are ideally suited for the analysis of sudden short-duration signal changes. Therefore, we have implemented a wavelet-based analysis and compared the results of this with a conventional FFT-based analysis. The temporal resolution, as measured by the half-width maximum, was significantly better for the continuous wavelet transform (CWT), mean (SD) 8.40 (8.82) ms, compared with the 128-point FFT, 12.92 (9.70) ms, and 64-point FFT, 10.80 (5.69) ms. Time localization of the CWT for the embolic signal was also significantly better than the FFT. The wavelet transform appears well suited to the analysis of embolic signals offering superior time resolution and time localization to the FFT.

Carotid Stenosis↗
PubMed1998

Protein structure analysis using the resonant recognition model and wavelet transforms.

An approach based on the resonant recognition model and the discrete wavelet transform is introduced here for characterising proteins' biological function. The protein sequence is converted into a numerical series by assigning the electron-ion interaction potential to each amino acid from N-terminal to C-terminal. A set of peaks is found after performing a wavelet transform onto a numerical series representing a group of homologous proteins. These peaks are related to protein structural and functional properties and named characteristic vector of that protein group. Further more, the amino acids contributing mostly to a protein's biological functions, the so-called 'hot spots' amino acids, are predicted by the continuous wavelet transform. It is found that the hot spots are clustered around the protein's cleft structure. The wavelets approach provides a novel methods for amino acid sequence analysis as well as an expansion for the newly established macromolecular interaction model: the resonant recognition model.

Amino Acid Sequence↗
PubMed2005

Multiple endocrine neoplasia type 2 and the RET protooncogene: from bedside to bench to bedside.

Although the initial characterization of the various MEN-2 associated phenotypes (familial medullary thyroid cancer, multiple endocrine neoplasia 2A and 2B) evolved at the bedside, it was at the bench where the underlying RET (REarranged during Transfection) germline mutations were identified. Molecular information has revolutionized our understanding and continues to transform the clinical management of this fascinating endocrine tumor syndrome of neural crest derivation, which consists of medullary thyroid cancer, pheochromocytoma, and parathyroid hyperplasia/adenoma. DNA-based identification of RET carriers did not require comprehension of the gene, but was a prerequisite for clarifying gene function and devising biologic compounds blocking RET phosphorylation. With the continuing expansion of our knowledge about the underlying molecular mechanisms and our growing therapeutic abilities, multiple endocrine neoplasia type 2 is gradually returning home to the bedside, closing the loop from bedside to bench to bedside.

Adenoma↗
PubMedDate not supplied

[Comparative study of the morphofunctional organization of tissues of different regions of the rat brain in culture].

The morphological organization and spontaneous electrical activity of neurones of the hippocampus, visual cortex and cerebellum of one- two-day old rats were studied during prolonged cultivation (up to 35 days) of explants under indentical conditions in vitro. Differentiation of cells, myelinization of axons and formation of synapses between the neurones were observed. A continuous and periodic types of unit activity were recorded which, for the hippocampus did not depend on the time of cultivation and units' location in the explant. The cerebral cortex cultures displayed a transition of continuous unit activity to a periodic one after a two-week development of the explants in vitro. The process coincides with the increase in the number of synapses in the culture and their structural maturation. The periodic discharges observed in mature cultures of the cerebral cortex and in the central part of the cerebellum explants, are transformed into continuous ones under the action ofmagnesium ions.

Animals↗
PubMed2006

SADE3: an effective system for automated detection of epileptiform events in long-term EEG based on context information.

Interictal spike detection is a time-consuming, low-efficiency task, but is important to epilepsy diagnosis. Automated systems reported to date usually have their practical efficacy compromised by elevated rates of false-positive detections per minute, which are caused mainly by the influence of artifacts (such as noise activity and ocular movements) and by the adoption of single or simple approaches. This work describes the development of a hybrid system for automatic detection of spikes in long-term electroencephalogram (EEG), named System for Automatic Detection of Epileptiform Events in EEG (SADE(3)), which uses wavelet transform, neural networks and artificial intelligence procedures to recognize epileptic and to reject non-epileptic activity. The system's pre-processing stage filters the EEG epochs with the Coiflet wavelet function, which showed the closest correlation to epileptogenic (EPG) activity, in opposition to some other wavelet functions that did not correlate with these events. In contrast to current attempts using continuous wavelet transform, we chose to work with fast wavelet transform to reduce processing time and data volume. Detail components at appropriate decomposition levels were used to accentuate spikes, sharp waves, high-frequency noise activity and ocular artifacts. These four detailed components were used to train four specialized neural networks, designed to detect and classify the EPG and non-EPG events. An expert module analyzes the networks' outputs, together with multichannel and context information and concludes the detection. The system was evaluated with 126,000 EEG epochs, obtained from seven different patients during long-term monitoring, under diverse behavior and mental states. More than 6,721 spikes and sharp waves were previously identified by three experienced human electroencephalographers. In these tests, the SADE(3) system simultaneously achieved 70.9% sensitivity, 99.9% specificity and a rate of 0.13 false-positives per minute, indicating its usefulness and low vulnerability to artifact influence. After tests, the SADE(3) system showed itself to be able to process bipolar cortical EEG records, from long-term monitoring, up to 32 channels, without any data preparation or event positioning. At the same time, SADE(3) revealed a high capacity to reject non-epileptic paroxysms, robustness in relation to a variety of spike morphologies, flexibility in adjustment of performance rates and the capacity to actually save time during EEG reading. Furthermore, it can be adapted to other applications for pattern recognition, with simple adjustments.

Artifacts↗
PubMed1996

Induction of polyploidy in adenovirus E1-transformed cells by the mitotic inhibitor colcemid.

Adenovirus-transformed cells were tested for their ability to synthesize DNA in the presence of cell cycle inhibitory drugs. We show that transformed cells are completely resistant to the mitotic inhibitor colcemid, partly resistant to lovastatin, mimosine, aphidicolin and genistein but not to hydroxyurea or thymidine. When treated with colcemid, AdE1-transformed cells continue to synthesize DNA but do not divide and, therefore, become highly polyploid. This effect is dependent on the presence of both E1A and E1B.

Adenovirus E1 Proteins↗
PubMed2001

High-efficiency non-viral transfection of primary chondrocytes and perichondrial cells for ex-vivo gene therapy to repair articular cartilage defects.

BACKGROUND: Primary perichondrial cells and chondrocytes have been used to repair articular cartilage defects in tissue engineering studies involving various animal models. Transfection of these cells with a gene that induces chondrocytic phenotype may form an ideal method to affect tissue engineering of articular cartilage. DESIGN: A protocol for high-efficiency transfection of primary perichondrial and cartilage cells was optimized. Plasmids carrying the marker beta-galactosidase (beta-gal), PTHrP and TGF-beta1 genes driven by a strong mammalian promoter were transfected into primary perichondrial cells and chondrocytes. A three-step method was used to achieve high efficiency of transfection: (1) permeabilization of primary cells using a mild detergent, (2) association of plasmid DNAs with a polycationic (poly-l-lysine) core covalently linked to a receptor ligand (transferrin), (3) introduction of cationic liposomes to form the quaternary complex. For in-vivo assessment, polylactic acid (PLA) scaffolds seeded with beta-gal transfected perichondrial cells were implanted into experimentally created osteochondral defects in rabbit knees for 1 week. RESULTS: The efficiency of transfection was determined to be over 70%in vitro. The transformed cells continued to express beta-gal, in vivo for the entire test period of 7 days. Furthermore, primary perichondrial cells transfected with TGF-beta1 and PTHrP over-expressed their cognate gene products. CONCLUSION: The ability to transfect autologous primary perichondrial cells and chondrocytes with high efficiency using a non-viral system may form a first step towards tissue engineering with these transformed cells to repair articular cartilage defects.

Animals↗
PubMed2003

Hidden corrosion detection in aircraft aluminum structures using laser ultrasonics and wavelet transform signal analysis.

Preliminary results of hidden corrosion detection in aircraft aluminum structures using a noncontact laser based ultrasonic technique are presented. A short laser pulse focused to a line spot is used as a broadband source of ultrasonic guided waves in an aluminum 2024 sample cut from an aircraft structure and prepared with artificially corroded circular areas on its back surface. The out of plane surface displacements produced by the propagating ultrasonic waves were detected with a heterodyne Mach-Zehnder interferometer. Time-frequency analysis of the signals using a continuous wavelet transform allowed the identification of the generated Lamb modes by comparison with the calculated dispersion curves. The presence of back surface corrosion was detected by noting the loss of the S(1) mode near its cutoff frequency. This method is applicable to fast scanning inspection techniques and it is particularly suited for early corrosion detection.

Aircraft↗