The semantic interference effect in the picture-word paradigm: An event-related fMRI study employing overt responses

We used event-related functional magnetic resonance imaging (fMRI) to investigate neural responses associated with the semantic interference (SI) effect in the picture-word task. Independent stage models of word production assume that the locus of the SI effect is at the conceptual processing level (Levelt et al. [1999]: Behav Brain Sci 22:1-75), whereas interactive models postulate that it occurs at phonological retrieval (Starreveld and La Heij [1996]: J Exp Psychol Learn Mem Cogn 22:896-918). In both types of model resolution of the SI effect occurs as a result of competitive, spreading activation without the involvement of inhibitory links. These assumptions were tested by randomly presenting participants with trials from semantically-related and lexical control distractor conditions and acquiring image volumes coincident with the estimated peak hemodynamic response for each trial. Overt vocalization of picture names occurred in the absence of scanner noise, allowing reaction time (RT) data to be collected. Analysis of the RT data confirmed the SI effect. Regions showing differential hemodynamic responses during the SI effect included the left mid section of the middle temporal gyrus, left posterior superior temporal gyrus, left anterior cingulate cortex, and bilateral orbitomedial prefrontal cortex. Additional responses were observed in the frontal eye fields, left inferior parietal lobule, and right anterior temporal and occipital cortex. The results are interpreted as indirectly supporting interactive models that allow spreading activation between both conceptual processing and phonological retrieval levels of word production. In addition, the data confirm that selective attention/response suppression has a role in resolving the SI effect similar to the way in which Stroop interference is resolved. We conclude that neuroimaging studies can provide information about the neuroanatomical organization of the lexical system that may prove useful for constraining theoretical models of word production. (C) 2001 Wiley-Liss, Inc.

Functional annotation of a full-length mouse cDNA collection

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.

Cationic drug pharmacokinetics in diseased livers determined by fibrosis index, hepatic protein content, microsomal activity, and nature of drug

The disposition kinetics of six cationic drugs in perfused diseased and normal rat livers were determined by multiple indicator dilution and related to the drug physicochemical properties and liver histopathology. A carbon tetrachloride (CCl4)induced acute hepatocellular injury model had a higher fibrosis index (FI), determined by computer-assisted image analysis, than did an alcohol-induced chronic hepatocellular injury model. The alcohol-treated group had the highest hepatic alpha(1)- acid glycoprotein, microsomal protein (MP), and cytochrome P450 (P450) concentrations. Various pharmacokinetic parameters could be related to the octanol-water partition coefficient (log P-app) of the drug as a surrogate for plasma membrane partition coefficient and affinity for MP or P450, the dependence being lower in the CCl4-treated group and higher in the alcohol-treated group relative to controls. Stepwise regression analysis showed that hepatic extraction ratio, permeability-surface area product, tissue-binding constant, intrinsic clearance, partition ratio of influx (k(in)) and efflux rate constant (k(out)), and k(in)/k(out) were related to physicochemical properties of drug (log P-app or pK(a)) and liver histopathology (FI, MP, or P450). In addition, hepatocyte organelle ion trapping of cationic drugs was evident in all groups. It is concluded that fibrosis-inducing hepatic disease effects on cationic drug disposition in the liver may be predicted from drug properties and liver histopathology.

Associations between human liver and kidney cadmium content and immunochemically detected CYP4A11 apoprotein

This present study was undertaken to assess potential effects of cadmium on CYP4A11 apoprotein in human liver and kidney as detected by Western blotting using a highly specific anti-peptide antibody. Liver and kidney cortex samples were autopsy specimens of 37 individuals (26 mates and I I females) whose ages ranged from 3 to 89 years. All were Caucasians who had not been exposed to cadmium in the workplace. Reduced CYP4A11 apoprotein levels were found in chronic hepatitis samples and in liver samples showing fatty changes. In contrast, increased CYP4A11 apoprotein levels were found in liver samples having higher cadmium content compared to the lower cadmium content samples. Increased CYP4A11 levels were also found in liver samples from female donors, compared to male donors; the difference being attributable to higher female liver cadmium burden. In distinction to liver, lowered CYP4A11 levels were seen in the kidney cortex samples which have high cadmium content, It is proposed here that the difference between the absolute cadmium burden of the liver and kidney samples may be responsible for the different patterns of expression of CYP4A11 in these two tissues. Further, since cadmium exposure may be associated with derangement in blood pressure control, it is interesting to note the possible relationship between altered CYP4A11-dependent production of arachidonic acid hydroxy and epoxy metabolites in kidney cortex and altered control of blood pressure. Our findings provide a possible link between these observations. (C) 2002 Elsevier Science Inc. All rights reserved.

Selenium content of Australian foods: A review of literature values

The aim of this study was to review the published literature values for the selenium content of Australian foods. A secondary aim was to compare the results for Australian foods with food composition data from international sources to investigate the extent of geographical variation. Published food composition data sources for the selenium content in Australian foods were identified and assessed for data quality using established criteria. The selenium content is available for 148 individual food items. The highest values found are for fish (12.0-63.2 mug/100 g), meats (4.75-37.9 mug/100 g) and eggs (9.00-41.4 mug/100 g), followed by cereals (1.00-20.3 mug/100 g). Moderate levels are seen in dairy products (2.00-7.89 mug/100 g) while most fruits and vegetables have low levels (trace-3.27 mug/100 g). High selenium foods show the greatest level of geographical variation, with foods from the United States generally having higher selenium levels than Australian foods and foods from the United Kingdom and New Zealand having lower levels. This is the first attempt to review the available literature for selenium composition of Australian foods. These data serve as an interim measure for the assessment of selenium intake for use in epidemiological studies of diet-disease relationships. (C) 2002 Published by Elsevier Science Ltd.

Analysis of the mouse transcriptome based on functional annotation of 60,770 full-length cDNAs

Only a small proportion of the mouse genome is transcribed into mature messenger RNA transcripts. There is an international collaborative effort to identify all full-length mRNA transcripts from the mouse, and to ensure that each is represented in a physical collection of clones. Here we report the manual annotation of 60,770 full-length mouse complementary DNA sequences. These are clustered into 33,409 'transcriptional units', contributing 90.1% of a newly established mouse transcriptome database. Of these transcriptional units, 4,258 are new protein-coding and 11,665 are new non-coding messages, indicating that non-coding RNA is a major component of the transcriptome. 41% of all transcriptional units showed evidence of alternative splicing. In protein-coding transcripts, 79% of splice variations altered the protein product. Whole-transcriptome analyses resulted in the identification of 2,431 sense-antisense pairs. The present work, completely supported by physical clones, provides the most comprehensive survey of a mammalian transcriptome so far, and is a valuable resource for functional genomics.

Application of quantitative analytical electron microscopy to the mineral content of insect cuticle

Quantification of calcium in the cuticle of the fly larva Exeretonevra angustifrons was undertaken at the micron scale using wavelength dispersive X-ray microanalysis, analytical standards, and a full matrix correction. Calcium and phosphorus were found to be present in the exoskeleton in a ratio that indicates amorphous calcium phosphate. This was confirmed through electron diffraction of the calcium-containing tissue. Due to the pragmatic difficulties of measuring light elements, it is not uncommon in the field of entomology to neglect the use of matrix corrections when performing microanalysis of bulk insect specimens. To determine, firstly, whether such a strategy affects the outcome and secondly, which matrix correction is preferable, phi-rho (z) and ZAF matrix corrections were contrasted with each other and without matrix correction. The best estimate of the mineral phase was found to be given by using the phi-rho (z) correction. When no correction was made, the ratio of Ca to P fell outside the range for amorphous calcium phosphate, possibly leading to flawed interpretation of the mineral form when used on its own.

A mathematical model of concentrate solids content for the wet drum magnetic separator

Low concentrate density from wet drum magnetic separators in dense medium circuits can cause operating difficulties due to inability to obtain the required circulating medium density and, indirectly, high medium solids losses. The literature is almost silent on the processes controlling concentrate density. However, the common name for the region through which concentrate is discharged-the squeeze pan gap-implies that some extrusion process is thought to be at work. There is no model of magnetics recovery in a wet drum magnetic separator, which includes as inputs all significant machine and operating variables. A series of trials, in both factorial experiments and in single variable experiments, was done using a purpose built rig which featured a small industrial scale (700 mm lip length, 900 turn diameter) wet drum magnetic separator. A substantial data set of 191 trials was generated in this work. The results of the factorial experiments were used to identify the variables having a significant effect on magnetics recovery. It is proposed, based both on the experimental observations of the present work and on observations reported in the literature, that the process controlling magnetic separator concentrate density is one of drainage. Such a process should be able to be defined by an initial moisture, a drainage rate and a drainage time, the latter being defined by the volumetric flowrate and the volume within the drainage zone. The magnetics can be characterised by an experimentally derived ultimate drainage moisture. A model based on these concepts and containing adjustable parameters was developed. This model was then fitted to a randomly chosen 80% of the data, and validated by application to the remaining 20%. The model is shown to be a good fit to data over concentrate solids content values from 40% solids to 80% solids and for both magnetite and ferrosilicon feeds. (C) 2003 Elsevier Science B.V. All rights reserved.

Media Convergence's Third Wave Content Streaming

Movies, pieces of music, books, or newspapers can all be expressed in the same binary code. Discrete forms of analogue media are just different dialects of the language of computerese. Content is becoming a very liquid asset. To take Marshall McLuhan's famed dictum a step further: The message is now independent of the medium

Codon usage bias and A+T content variation in human papillomavirus genomes

We analyzed the codon usage bias of eight open reading frames (ORFs) across up to 79 human papillomavirus (HPV) genotypes from three distinct phylogenetic groups. All eight ORFs across HPV genotypes show a strong codon usage bias, amongst degenerately encoded amino acids, toward 18 codons mainly with T at the 3rd position. For all 18 degenerately encoded amino acids, codon preferences amongst human and animal PV ORFs are significantly different from those averaged across mammalian genes. Across the HPV types, the L2 ORFs show the highest codon usage bias (73.2 +/- 1.6% and the E4 ORFs the lowest (51.1 +/- 0.5%), reflecting as similar bias in codon 3rd position A + T content (L2: 76.1 +/- 4.2%; E4: 58.6 +/- 4.5%). The E4 ORF, uniquely amongst the HPV ORFs, is G + C rich, while the other ORFs are A + T rich. Codon usage bias correlates positively with A + T content at the codon 3rd position in the E2, E6, L1 and L2 ORFs, but negatively in the E4 ORFs. A general conservation of preferred codon usage across human and non-human PV genotypes whether they originate from a same supergroup or not, together with observed difference between the preferred codon usage for HPV ORFs and for genes of the cells they infect, suggests that specific codon usage bias and A + T content variation may somehow increase the replicational fitness of HPVs in mammalian epithelial cells, and have practical implications for gene therapy of HPV infection. (C) 2003 Elsevier B.V. All rights reserved.