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PubMed2001

Dis1/TOG universal microtubule adaptors - one MAP for all?

Microtubules play central roles in various cellular processes in eukaryotes. The dynamics and organisation of interphase microtubules and mitotic spindles are dramatically altered during the cell cycle and development. However, the molecular mechanisms underlying this dynamic behaviour remain to be understood. In recent years, a novel family of microtubule-associated proteins (MAPs), the Dis1/TOG family, has emerged as a versatile regulator of microtubule function. These MAPs are highly conserved in eukaryotes from yeasts and plants to humans. The localisation and function of these MAPs are not determined simply by their intrinsic microtubule-binding activity. Instead this family executes its diverse roles by interacting with other regulatory molecules, including microtubule motors and centrosomal proteins. The modular structure of these MAPs may allow them to interact with multiple proteins and thereby be involved in a wide variety of microtubule and spindle functions.

Animals↗
PubMed1999

Brain activation during working memory 1 month after mild traumatic brain injury: a functional MRI study.

OBJECTIVE: To assess patterns of regional brain activation in response to varying working memory loads shortly after mild traumatic brain injury (MTBI). BACKGROUND: Many individuals complain of memory difficulty shortly after MTBI. Memory performance in these individuals can be normal despite these complaints. METHODS: Brain activation patterns in response to a working memory task (auditory n-back) were assessed with functional MRI in 12 MTBI patients within 1 month of their injury and in 11 healthy control subjects. RESULTS: Brain activation patterns differed between MTBI patients and control subjects in response to increasing working memory processing loads. Maximum intensity projections of statistical parametric maps in control subjects showed bifrontal and biparietal activation in response to a low processing load, with little additional increase in activation associated with the high load task. MTBI patients showed some activation during the low processing load task but significantly increased activation during the high load condition, particularly in the right parietal and right dorsolateral frontal regions. Task performance did not differ significantly between groups. CONCLUSION: MTBI patients differed from control subjects in activation pattern of working memory circuitry in response to different processing loads, despite similar task performance. This suggests that injury-related changes in ability to activate or to modulate working memory processing resources may underlie some of the memory complaints after MTBI.

Adult↗
PubMed2000

Category differences in brain activation studies: where do they come from?

Differences in the neural processing of six categories of pictorial stimuli (maps, body parts, objects, animals, famous faces and colours) were investigated using positron emission tomography. Stimuli were presented either with or without the written name of the picture, thereby creating a naming condition and a reading condition. As predicted, naming increased the demands on lexical processes. This was demonstrated by activation of the left temporal lobe in a posterior region associated with name retrieval in several previous studies. This lexical effect was common to all meaningful stimuli and no category-specific effects were observed for naming relative to reading. Nevertheless, category differences were found when naming and reading were considered together. Stimuli with greater visual complexity (animals, faces and maps) enhanced activation in the left extrastriate cortex. Furthermore, map recognition, which requires greater spatio-topographical processing, also activated the right occipito-parietal and parahippocampal cortices. These effects in the visuo-spatial regions emphasize inevitable differences in the perceptual properties of pictorial stimuli. In the semantic temporal regions, famous faces and objects enhanced activation in the left antero-lateral and postero-lateral cortices, respectively. In addition, we showed that the same posterior left temporal region is also activated by body parts. We conclude that category-specific brain activations depend more on differential processing at the perceptual and semantic levels rather than at the lexical retrieval level.

Adult↗
PubMed1989

The 5' end of U3 snRNA can be crosslinked in vivo to the external transcribed spacer of rat ribosomal RNA precursors.

From previous work it was known that U3 RNA is hydrogen bonded to nucleolar 28 S to 35 S RNA and can be covalently crosslinked to RNA of greater than 28 S by irradiation in vivo with long-wave ultraviolet light in the presence of 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT psoralen). Here we use a novel sandwich blot technique to identify these large nucleolar RNA species as rRNA precursors and to map the site(s) of crosslinking in vivo. The crosslink occurs between one or more residues near the 5' end of U3 RNA and a 380 nucleotide region of the rat rRNA external transcribed spacer (ETS1). We have sequenced this region of the rat ETS and we show that it includes an RNA-processing site analogous to those previously mapped to approximately 3.5 kb upstream from the 5' end of mouse and human 18 S rRNAs.

Animals↗
PubMed1979

Contour analysis in plastic and reconstructive surgery.

Three-dimensional measurements of living objects may be made using various biostereometric techniques. Moire topography provides one-step contour line maps. It is a potential low-cost adjuvant to current photographic and cephalometric techniques for documentation of surface deformities. A relatively simple apparatus may be used with instant-processing film to produce immediate contour maps superimposed on the object image on the film. There is significant qualitative information highlighted by the fine resolution of the system. This immediate had data may be quantitatively analyzed by hand with ruler and/or caliper. In the future, off-line quantitative analysis may be made by computer. Geometric constraints of the system and examples of use of the technique are provided. Emphasis is placed on facial asymmetries that are difficult to analyze from plain photographs and inaccessible to data analysis from lateral cephalometric roentgenographs.

Adolescent↗
PubMed1996

Accuracy of least squares designed spatial FIR filters for segmentation of images of fluorescence stained cell nuclei.

A method for accurate, real-time image segmentation is needed for the development of a fully automated image cytometer that combines the speed and case-of-use of flow cytometry with the detailed morphometry of imaging. Object intensity variation and inherent optical blur make real-time segmentation challenging. The best spatial finite impulse response (FIR) filter, implemented as a convolution, was tested for sharpening edges and creating the required contrast. The filter and threshold segmentation steps were treated as a two-category linear classifier. Best 3 x 3 through 25 x 25 filters were designed utilizing the perceptron criterion and nonlinear least squares, and tested on ten montage images of a combined 1,070 manually segmented DAPI stained cell nuclei. The resulting image contrast, or class separation, led to simple automatic thresholding via the histogram intermodal minimum. Image segmentation accuracy began to plateau at 7 x 7 filters and did not increase above 15 x 15. Little loss in accuracy occurred with application to the images not used for design. This segmentation method provides a systematic, fast and accurate means of creating binary object maps useful for subsequent measurement, processing and cell classification.

3T3 Cells↗
PubMed2000

Activation of bovine oocytes by specific inhibition of cyclin-dependent kinases.

Activation of bovine oocytes by experimental procedures that closely mimic normal fertilization and allow to obtain haploid oocytes is essential both for intracytoplasmic sperm injection (ICSI) and for nuclear transfer. Therefore, with the goal of producing haploid activated oocytes, this study evaluated whether bohemine, either alone or in combination with ionomycin, is able to activate young matured bovine oocytes. Furthermore, the effect of bohemine on the patterns of DNA synthesis after pronuclear formation as well as changes in histone H1 kinase and MAP kinase activities during the process of activation were studied. Our results with bohemine show that the specific inhibition of CDKs in metaphase II bovine oocytes induces parthenogenetic activation in a dose-dependent manner (25, 50, and 100 microM, respectively), either alone (3%, 30%, and 50%) or in combination with ionomycin (30%, 70%, and 87.5%). A single pronucleus and extrusion of the second polar body was observed (97%) when Ca(2+) influx was stimulated in the presence of bohemine, although pronuclear formation without polar body extrusion was observed when bohemine was used alone. Bohemine-activated oocytes started to synthesize DNA in the first hour (37%) after their removal from bohemine-supplemented medium (6-7 hr post-activation; hpa). A high synchrony in the S-phase was registered with more than 85% of parthenotes actively synthesizing DNA 8 hpa. By contrast, DNA synthesis was absent in oocytes cultured for 4, 6, and 8 hpa in the presence of bohemine and a low rate was observed by those cultured for 18 hr (30%) in bohemine-supplemented medium. This confirms the ability of the inhibitor to arrest the cell cycle in the G1/S boundary for at least 8 hr. A drop in histone H1 kinase activity was observed in bohemine-activated oocytes. The activity of MBP kinase decreased later than histone H1 kinase and even 4 hr after inomycin-bohemine treatment at least half of this activity was still detectable. Then, the MBP kinase activity decreased and the lowest level could be seen 6-8 hpa. In summary, our study shows that in vitro matured bovine oocytes can be successfully activated by a synthetic inhibitor of CDKs. This effect can be improved by combination with ionomycin. The targeting of CDKs in the way to activate bovine oocytes can be an approach to improve the efficiency of mammalian oocyte activation.

Animals↗
PubMed2005

Potential of NIR-FT-Raman spectroscopy in natural carotenoid analysis.

This paper demonstrates the special advantages of FT-Raman spectroscopy for in situ studies of several carotenoids that occur ubiquitously in the plant kingdom. Spectra obtained from various tissues of a range of plant species indicate that the wavenumber location of C=C stretching vibrations is mainly influenced both by the length as well as by the terminal substituents of the polyene chain of carotenoids and by their interaction with other plant constituents. The obtained results show also the usefulness of Raman spectroscopy in the investigation of cis-trans isomerization of carotenoids during processing. Additionally, 2-D Raman mappings present a unique possibility to evaluate the individual distribution of carotenoids in the intact plant tissue; in this context different 7-, 8-, and 9-double bond conjugated carotenoids can be analyzed independently in the same sample. Furthermore, the use of Raman spectroscopy for in situ detection of unstable substances such as epoxycarotenoids is discussed.

Carotenoids↗
PubMed1990

Preparing and analyzing fractured archaeological fibers.

A technique was developed to prepare archaeological fiber cross sections for electron microscopic examination and x-ray analysis. Use of this new method allows chemical and morphological information to be obtained from the interior of a single fiber or yarn. Fibers are fractured while frozen and then freeze dried. Following mounting and carbon coating, fibers are examined by scanning and backscatter electron microscopy and then analyzed by using energy-dispersive spectrometry. Elemental distribution is mapped by using image-processing software. In this report, the described technique is employed in the examination of ancient fibers from three different long-term storage environments (moist buried, dry buried, museum stored). Data obtained by examining the interior of fibers such as these provide insight into the conditions of a fiber's growth, the treatments applied during the fiber's processing and use, and the conditions in which the fiber was stored.

Archaeology↗
PubMed1993

Ventral tegmental self-stimulation selectively induces opioid peptide release in rat CNS.

Intracranial self-stimulation (ICS) is thought to activate neuronal systems involved in processing natural reinforcing agents. Metabolic mapping studies have previously demonstrated a subset of CNS structures specifically engaged by ICS in animals receiving stimulation actively vs. passively. Since opiates are known to enhance ICS behavior and presumably its reinforcing properties, the current study addressed the question of the role of opioid peptides as mediators of ICS. Rats were trained on a fixed ration (FR) 20 schedule of responding maintained by ICS. Following response stabilization, rats were assigned either to an active or a corresponding yoked stimulation group at 1 of 2 schedules of reinforcement (i.e., FR1-YFR1, FR20-YFR20, or sedentary control), and opioid peptide release was inferred from in vivo receptor occupancy. Autoradiographic analyses identified 3 groups of structures. Treatment-induced alterations in occupancy were seen in the medial dorsal nucleus of the thalamus, basolateral amygdala, ventral pallidum, medial habenula, dorsal raphe, posterior hypothalamus, substantia nigra pars compacta, agranular preinsular cortex, and zona incerta. Depending upon the structure, peptide release was dependent upon stimulus contingency (active vs. yoked) and/or schedule (FR1 vs. FR20). Evidence for ICS-induced inhibition of peptide release was found in the habenula and preinsular cortex. Nine additional structures, all components of, or receiving projections from, the limbic system, revealed complex interactions between ICS treatment and the electrode side. Finally, a widespread ipsilateral increase in receptor binding was seen rostrally from the cingulate, olfactory tubercle, and nucleus accumbens, along the lateral hypothalamus and hippocampus, and extending caudally to the substantia nigra and ventral tegmentum. These later effects appear to be related to stimulation-induced changes in blood flow and subsequent ligant presentation increases. Collectively, these data point towards the ability of rewarding brain stimulation to activate discrete neuronal opioid systems contingent upon specific behavioral as well as stimulus conditions.

Amygdala↗
PubMed1998

Identification of phosphorylated proteins associated with the fibroblast growth factor receptor type I during early Xenopus development.

Signaling through the FGF receptor (FGFR) is required for mesoderm induction in Xenopus. Some of the downstream signaling molecules implicated in this developmental process include Ras, Raf and MAP kinase. In a previous report, we demonstrated that PLC gamma 1, Grb-2, SOS and Nck were associated with activated FGFR1s in a signaling complex in Xenopus blastulae. In addition, several unidentified phosphotyrosylproteins were present in the FGFR1 complex. Here we identify three of these proteins as Ras-GAP, the p85 of P13'K and SHP2, while demonstrating that c-Src and She were not associated with the FGFR1. Furthermore, we show that three additional phosphotyrosylproteins from the FGFR1 complex specifically bound to the adaptor molecule Nck.

Animals↗
PubMed1997

Informativity and asymmetry in comparisons.

We propose an account of comparison asymmetries based on viewing comparison as a process of structural alignment and mapping. Specifically, we hypothesize that (1) comparison asymmetries result from directional differences in informativity, and that (2) asymmetries can therefore be predicted from the relative degree of systematicity or conceptual coherence of the items being compared. In Experiment 1, we found a clear preference for placing the more systematic of two passages in the base position of a comparison. Experiments 1 and 2 further showed that structural alignability is crucial in obtaining such asymmetries. In Experiment 3, we found that asymmetries are predicted by the relative systematicity of the comparisons items rather than by the relative size of the distinctive feature sets. These results are inconsistent with accounts of asymmetry based on feature contrast or stimulus bias. In Experiments 4 through 6, we tested the functional implications of our account by examining inference projection and perceived informativity across asymmetric comparisons. Critically, comparisons having the more systematic item as the base were more likely to result in inference projection and other forms of target modification and were rated as more informative than reverse comparisons. We conclude by demonstrating that this account can explain comparison asymmetries without positing underlying asymmetries in subjective similarity, and that it offers a unified approach to the directionality of literal comparisons, analogies, and metaphors.

Adult↗
PubMed2000

A geographic information assessment of birth weight and crop production patterns around mother's residence.

A landscape approach using remote sensing (RS) and geographic information system (GIS) technologies was developed to identify the proximity of maternal residence to agricultural areas, and the association between crop production patterns around mothers residences and low birth weight was evaluated. Satellite data obtained for Weld County, Colorado, in 1991 and 1993 were digitally processed to generate crop location maps for this study. GIS procedures were then used to determine crop types within 300- and 500-m circular zones around mothers' homes for 125 births that occurred from 1991 to 1993 in the study area. The relationships between different crop patterns around the mothers' residences and the birth weight of babies were investigated while controlling for potential confounding variables. The results indicated that low birth weight was associated with total crop production area within a 300-m buffer zone around mothers' residences (P=0.058). When each of the study crops was considered separately, low birth weight was associated with sugar beet production (P=0.05) and corn production (P=0.1) within both the 300- and the 500-m buffer zones. This RS/GIS approach provides clues to the potential relationships between birth weight and crop production near the residence.

Adult↗
PubMed1997

Diffusion-weighted MRI of myelination in the rat brain following treatment with gonadal hormones.

Previous studies have demonstrated the ability of high-resolution diffusion-weighted MRI to show maturation of white-matter structures in the developing rat brain. The purpose of this study was to investigate the influence of gonadal steroid hormones on the rate of this development. Starting from their second postnatal day, 16 rat-pups of either sex were repeatedly treated with subcutaneous implants containing 17-beta estradiol or delta-androstene 3,17 dione, respectively. Serial T1-, T2- and diffusion-weighted MRI was performed weekly for 8 weeks using a 4.7 T unit. Maturation of anterior optic pathways and hemisphere commissures was assessed. Diffusion-weighted images were processed to produce "anisotropy index maps", previously shown to be sensitive to white-matter maturation. Compared with untreated rat-pups, estrogen-treated animals showed accelerated, and testosterone-treated animals delayed maturation on anisotropy index maps and histological sections. In all animals, maturational changes appeared earlier on anisotropy index maps than on other MRI sequences or on myelin-sensitive stained sections. Diffusion-weighted imaging, and the construction of spatial maps sensitive to diffusion anisotropy, seem to be the most sensitive approach for the detection of maturational white-matter changes, and thus may hold potential for early diagnosis of temporary delay or permanent disturbances of white-matter development.

Androstenediol↗
PubMed2006

Groundwater vulnerability assessment for organic compounds: fuzzy multi-criteria approach for Mexico city.

This study was based on a groundwater vulnerability assessment approach implemented for the Mexico City Metropolitan Area (MCMA). The approach is based on a fuzzy multi-criteria procedure integrated in a geographic information system. The approach combined the potential contaminant sources with the permeability of geological materials. Initially, contaminant sources were ranked by experts through the Analytic Hierarchy Process. An aggregated contaminant sources map layer was obtained through the simple additive weighting method, using a scalar multiplication of criteria weights and binary maps showing the location of each source. A permeability map layer was obtained through the reclassification of a geology map using the respective hydraulic conductivity values, followed by a linear normalization of these values against a compatible scale. A fuzzy logic procedure was then applied to transform and combine the two map layers, resulting in a groundwater vulnerability map layer of five classes: very low, low, moderate, high, and very high. Results provided a more coherent assessment of the policy-making priorities considered when discussing the vulnerability of groundwater to organic compounds. The very high and high vulnerability areas covered a relatively small area (71 km(2) or 1.5% of the total study area), allowing the identification of the more critical locations. The advantage of a fuzzy logic procedure is that it enables the best possible use to be made of the information available regarding groundwater vulnerability in the MCMA.

Cities↗
PubMed2001

Prenatal exposure to ethanol induces leptomeningeal heterotopia in the cerebral cortex of the rat fetus.

Pregnant rats were fed an ethanol-containing liquid diet between gestational day (GD) 10 and GD 21. Leptomeningeal heterotopias were observed in the cerebral cortex of ethanol-exposed fetuses. They appeared on the brain surface of the lateral cortical region near the rhinal fissure, and were found more numerously in the rostral than the caudal region. These abnormalities contained certain neuronal perikarya, microtubule-associated protein (MAP) 1b-positive neuronal processes, and Rat-401-positive radial glial fibers. Immunostaining for Rat-401 revealed that the heterotopias protruded through breaches in the glia limitans. In adult rats exposed to ethanol prenatally, the heterotopias persisted in the lateral cortical region. We conclude that prenatal exposure to ethanol might induce defects in the glia limitans, resulting in the genesis of leptomeningeal heterotopias. These abnormalities may be related to mental retardation or the cognitive deficits associated with human fetal alcohol syndrome (FAS).

Alcohol-Induced Disorders, Nervous System↗
PubMed2005

Nocturnal changes in leaf growth of Populus deltoides are controlled by cytoplasmic growth.

Growing leaves do not expand at a constant rate but exhibit pronounced diel growth rhythms. However, the mechanisms giving rise to distinct diel growth dynamics in different species are still largely unknown. As a first step towards identifying genes controlling rate and timing of leaf growth, we analysed the transcriptomes of rapidly expanding and fully expanded leaves of Populus deltoides Bartr. ex. Marsh at points of high and low expansion at night. Tissues with well defined temporal growth rates were harvested using an online growth-monitoring system based on a digital image sequence processing method developed for quantitative mapping of dicot leaf growth. Unlike plants studied previously, leaf growth in P. deltoides was characterised by lack of a base-tip gradient across the lamina, and by maximal and minimal growth at dusk and dawn, respectively. Microarray analysis revealed that the nocturnal decline in growth coincided with a concerted down-regulation of ribosomal protein genes, indicating deceleration of cytoplasmic growth. In a subsequent time-course experiment, Northern blotting and real-time RT-PCR confirmed that the ribosomal protein gene RPL12 and a cell-cycle gene H2B were down-regulated after midnight following a decrease in cellular carbohydrate concentrations. Thus, we propose that the spatio-temporal growth pattern in leaves of P. deltoides primarily arises from cytoplasmic growth whose activity increases from afternoon to midnight and thereafter decreases in this species.

Carbohydrate Metabolism↗
PubMed2005

The neural effect of stimulus-response modality compatibility on dual-task performance: an fMRI study.

Recent fMRI studies suggest that the inferior frontal sulcus (IFS) is involved in the coordination of interfering processes in dual-task situations. The present study aims to further specify this assumption by investigating whether the compatibility between stimulus and response modalities modulates dual-task-related activity along the IFS. It has been shown behaviorally that the degree of interference, as measured by dual-task costs, increases in modality-incompatible conditions (e.g. visual-vocal tasks combined with auditory-manual tasks) as compared to modality-compatible conditions (e.g. visual-manual tasks combined with auditory-vocal tasks). Using fMRI, we measured IFS activity when participants performed modality-compatible and modality-incompatible single and dual tasks. Behaviorally, we replicated the finding of higher dual-task costs for modality-incompatible tasks compared to modality-compatible tasks. The fMRI data revealed higher activity along the IFS in modality-incompatible dual tasks compared with modality-compatible dual tasks when inter-individual variability in functional brain organization is taken into account. We argue that in addition to temporal order coordination (Szameitat et al., 2002), the IFS is involved in the coordination of cognitive processes associated with the concurrent mapping of sensory information onto corresponding motor responses in dual-task situations.

Association Learning↗