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PubMed1997

Categorization and perceptual learning: an analogue of the face inversion effect.

This paper reports two experiments that investigate the extent to which it is plausible to suppose that an associatively based mechanism for perceptual learning acts as the basis for the effects of inversion on identification, recognition, matching and discrimination of faces (and certain other stimuli rendered familiar by expertise, e.g. gundogs). In the first experiment, an inversion effect that is contingent both on familiarity with a category and on the category possessing prototypical structure is demonstrated using discrimination learning of chequerboard stimuli. The second experiment demonstrates that the inversion effect found in Experiment 1 can generalize to a recognition paradigm as well. These results are discussed within the framework provided by associative learning theory, and a parallel is drawn with models employing a norm-based coding in similarity space. The conclusion is that it would be remarkable if the inversion effects demonstrated with the abstract categories used in the experiments reported here were not implicated in the inversion effects found with other classes of stimuli, whilst conceding that the analogy is not complete, particularly in the case of faces.

Adolescent↗

PubMed1992

Dipyridamole-echocardiography: clinical usefulness following interventions.

Dipyridamole-echocardiography test response can be expressed not only in a black or white (positive vs negative) code but also, in positive tests, by a gray scale integrating the severity and extent of the dyssynergy as well as the ischemia-free stress time. The recognition of the dyssynergy is important to establish the diagnosis; however, the evaluation of the degree of the induced ischemia, stratified according to spatiotemporal coordinates, is even more important because it accurately predicts the coronary anatomical and functional situation, as well as the prognosis of the individual patient. Furthermore, the "shades of gray" in a positive response have proved useful in assessing the beneficial effects of several interventions: coronary angioplasty; coronary artery bypass surgery; thrombolysis; and medical antianginal therapy. Due to its excellent reproducibility, dipyridamole-echocardiography can play a pivotal role for simple, safe, fast, accurate, and objective assessment of therapeutic interventions, either mechanical or pharmacological, based upon the presence, timing, severity, and extent of dipyridamole-induced dyssynergy.

Angina Pectoris↗

PubMed1993

Morbidity registration and the fourth general practice morbidity survey in England and Wales.

The fourth morbidity survey in England and Wales is based on a population of 473,000 persons registered in 60 practices and cared for by 241 general practitioners. This presentation traces the evolution of morbidity surveys in England and Wales. That evolution has taken place against a background of advancing computer technology and the drift towards a paperless record. It is motivated by an increasing recognition of the need for data from primary health care an a realisation that a structured record is capable of servicing information needs without intermediary data sheets and coding procedures. The primary objectives of the study include assessment of disease prevalence by region, age-sex and social group; and to study trends over time. Morbidity and social data are collected in the practices and all relevant information stored on practice computers. At the end of the recording year, the computerised record for each patient is copied on to disks in an anonymized but uniquely identified form and transferred to the national Office of Population Censuses & Surveys for analysis. During the year, weekly extracts are taken of new episodes of illness in age and sex groupings which provide the basis of the Weekly Returns Service of the Royal College of General Practitioners.

Data Collection↗

PubMed2001

In what sense is implicit memory "episodic"? The effect of reinstating environmental context.

We consider three aspects of the term episodic. Previous literature shows implicit memory does not make conscious autobiographical reference but does code an item's intrinsic context (e.g., perceptual detail). Here, we consider extrinsic context--namely, that not directly processed as part of item identification and not overtly relevant to the task. Study-test mismatch in environmental context (outdoors vs. indoors) reduced memory in an explicit stem-cued recall task but had no effect on repetition priming in an implicit stem completion task. This was true even for very low frequency words. We support the view that implicit memory reflects traces within perceptual (or semantic) knowledge-based systems that are instance specific but do not code the full spatiotemporal context information necessary to support conscious recollection. We also interpret our results as consistent with differences in environmental context specificity between free recall and recognition.

Humans↗

PubMed2004

The cognitive processing of film and musical soundtracks.

Previous research has demonstrated that musical soundtracks can influence the interpretation, emotional impact, and remembering of film information. The intent here was to examine how music is encoded into the cognitive system and subsequently represented relative to its accompanying visual action. In Experiment 1, participants viewed a set of music/film clips that were either congruent or incongruent in their emotional affects. Selective attending was also systematically manipulated by instructing viewers to attend to and remember the music, film, or both in tandem. The results from tune recognition, film recall, and paired discrimination tasks collectively revealed that mood-congruent pairs lead to a joint encoding of music/film information as well as an integrated memory code. Incongruent pairs, on the other hand, result in an independent encoding in which a given dimension, music or film, is only remembered well if it was selectively attended to at the time of encoding. Experiment 2 extended these findings by showing that tunes from mood-congruent pairs are better recognized when cued by their original scenes, while those from incongruent pairs are better remembered in the absence of scene information. These findings both support and extend the "Congruence Associationist Model" (A. J. Cohen, 2001), which addresses those cognitive mechanisms involved in the processing of music/film information.

Adolescent↗

PubMed2001

A family of IGF-II mRNA binding proteins (IMP) involved in RNA trafficking.

During a search for trans-acting factors associating with insulin-like growth factor II (IGF-II) mRNAs, we recently identified a family of three IGF-II mRNA-binding Proteins (IMP1, IMP2 and IMP3) that exhibit multiple attachments to IGF-II leader 3 mRNA and the reciprocally imprinted H19 RNA. IMPs contain the unique combination of two RNA recognition motifs (RRMs) and four hnRNP K homology (KH) domains. IMP1 is orthologous to the chicken zipcode-binding protein (ZBP-1), and the mouse c-myc coding region determinant-binding protein (CRD-BP) that associates with beta-actin and c-myc mRNA, respectively. Moreover, the p62 protein identified in hepatocellular carcinoma represents a splice variant of IMP2, and IMP3 is orthologous to the Xenopus Vegetal 1 RNA-binding protein (Vgl-RBP/Vera). IMPs are produced in a biphasic fashion--initially during the early stages of embryogenesis and subsequently later in development. IMPs and their orthologues are predominantly cytoplasmic and are implicated in the transport of their RNA targets towards the leading edge in somatic cells and to the vegetal pole in Xenopus oocytes, respectively. RNA localization is a conserved mechanism of polarizing genetic information in the establishment of asymmetries during both embryogenesis and adult life, enabling local protein synthesis at final destinations within the cell. The identification of developmentally expressed zipcode-binding proteins indicates that RNA trafficking participates in processes such as cell-growth and migration during embryogenesis.

Amino Acid Sequence↗

PubMed1997

Detecting Repetitive DNA in Eukaryotes.

A detection software of repetitive elements, especially for Alu is designed according to the theory of the correspondence analysis. The results obtained on the test set of 38 gene sequences showed that the true-negative is about 5.8% and false-positive is about 4.8%. Also, the detailed description of Alu elements in the sequences in which the Alu elements are spliced into coding-regions and the successful search for Alu in large-scale T-cell receptor loci sequence showed that the software is a better tool for the recognition of repeat elements.

Journal Article↗

PubMed1990

Recognition by the DNA repair system of DNA structural alterations induced by reversible drug-DNA interactions.

Ditercalinium (NSC 335153) was synthesized as a bifunctional DNA intercalator. It is made of two 7-H pyridocarbazole rings joined by a rigid bis-ethyl bispiperidine chain. It binds to DNA with high affinity and elicits anti-tumor activity on a variety of animal tumors. 1H n.m.r. studies of ditercalinium bis-intercalated into d(CpGpCpG)2 have shown that the intercalation process occurs from the large groove of the DNA helix while the two intercalated rings are separated by two base pairs. Because of the linking chain rigidity of ditercalinium, DNA conformation has to be altered to permit the intercalation of the two rings. DNA must be bent toward the minor groove. In E. coli, ditercalinium elicits a specific toxicity on polA strains which is suppressed by an additional uvrA mutation. In vitro, the purified UvrA and UvrB proteins bind to the DNA-ditercalinium complex in an ATP dependent manner. The UvrABC complex induces single-strand nicks, but only when ditercalinium is bound to negatively supercoiled DNA. The life-time of the UvrAB-DNA-ditercalinium complex is greater than 50 min when free ditercalinium concentration is maintained constant in the incubation medium. The cytotoxicity of ditercalinium in E. coli results from the induction of a futile and abortive DNA repair. The reversible ditercalinium-DNA complex mimics a bulky DNA lesion, yet the UvrABC endonuclease is unable to cope with a reversible lesion since it cannot eliminate the causative agent. The interaction of UvrA and UvrB proteins has also been studied with DNA and other DNA-binding drugs forming high-affinity complexes such as distamycin. The Uvr protein recognition process appears to be associated with specific DNA structural alterations. In eukaryotic cells, ditercalinium is concentrated in mitochondria. Mitochondrial DNA is rapidly and totally degraded. Mitochondrial DNA coded proteins being no longer synthesized, the respiratory chain is progressively inactivated. The stimulation of the glycolytic pathway allows the cells to continue growth for several generations. Dihydro-orotate dehydrogenase is located in the inner membrane of mitochondria and its activity is dependent on mitochondria energization. It becomes inactive after ditercalinium treatment. A drop of the pyrimidine pool is then observed. Complementation of treated cells with uridine decreases 10-fold the ditercalinium toxicity. The cellular delayed toxicity of ditercalinium results from the slow induction of a pyrimidineless state associated with the progressive inactivation of mitochondria. The results show that DNA structural alterations induced by reversible drug-DNA complexes can be recognized by DNA repair enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1996

Binaural performance and aging.

Binaural performance is a general term that can be applied to a wide range of paradigms that involve listening with both ears. This review samples from across the spectrum of binaural tasks by highlighting recent studies that encapsulate certain aspects of binaural function. Studies of the precedence effect and binaural unmasking suggest that temporal coding in elderly listeners is degraded relative to young listeners and that this decline is not simply a function of reduced audiometric sensitivity. For higher tasks involving speech recognition in competing noise, the elderly show reduced binaural advantage, particularly when they also exhibit presbyacusic hearing loss. However, it should not be overlooked that the advantages of listening with two ears rather than one remain significant even in the presbyacusic listener.

Adult↗

PubMed1997

Human coproporphyrinogen oxidase. Biochemical characterization of recombinant normal and R231W mutated enzymes expressed in E. coli as soluble, catalytically active homodimers.

To obtain recombinant human coproporphyrinogen oxidase (CPX), a cDNA for the coding region of mature human CPX has been expressed in E. coli. CPX was produced as a fusion protein with glutathione S-transferase followed by the hexapeptide recognition site for thrombin cleavage just preceding first amino acid of the CPX protein. The human CPX was found to be in the soluble fraction. This previously unobtainable human heme synthetic enzyme was purified to electrophoretic homogeneity with a specific activity of 4200 nmol/hr./mg of protein using a Glutathione Sepharose 4B column and gel filtration. Recombinant human CPX exhibits homogeneous behavior during high performance liquid chromatography (HPLC) and the N-terminal sequence, confirmed by protein sequencing, revealed a single polypeptide chain. In its active form, human CPX is a homodimer. According to the hydrodynamic properties derived from analytical ultracentrifugation, dimeric CPX has a nearly globular shape. Additionally, naturally occurring Arg to Trp (R231W)-mutated CPX has been also expressed in E. coli and further characterized. The mutated enzyme has a Km value of 0.55 microM as compared to 0.30 microM for the wild type. The catalytic efficiency (specificity constant, kcat/Km) of the mutated CPX was four fold lower than wild-type enzyme. The activity measurement of the mutated enzyme showed higher thermal sensitivity as compared with wild type CPX. The measured pI for mutated CPX is 5.65, compared to 6.40 for wild type. The pH optima for the mutated and wild-type protein are 6.6 and 6.8, respectively. The R231W mutation of CPX does not affect dimer formation and both normal and mutated CPX exhibit identical sedimentation properties. The thermal denaturation of both wild type and mutant CPX was found to be irreversible. The mutated CPX contained a significant amount of tightly bound porphyrin coproporphyrin. No metal association was found either in wild type or in mutated CPX. The availability of the recombinant human CPX will aid in structural and mechanistic studies.

Amino Acid Sequence↗

PubMed1997

Genomic organization of the mouse reelin gene.

Reelin is the protein defective in reeler mice, an extensively studied model of brain development. The reelin gene (symbol Reln) codes for a protein of the extracellular matrix that contains eight successive repeats of 350 to 390 amino acids. In this work, we describe the genomic structure of the mouse reelin gene and the 5'-flanking genomic DNA sequences. The reelin gene is composed of 65 exons spread over approximately 450 kb of genomic DNA. We identified different reelin transcripts, formed by alternative splicing of a microexon as well as by use of two different polyadenylation sites. All splice sites conform to the GT-AG rule, except for the splice donor site of intron 30, which is GC instead of GT. A processed pseudogene is present in intron 42. Its nucleotide sequence is 86% identical to the sequence of the rat RDJ1 cDNA, which codes for a DnaJ-like protein of the Hsp40 family. Comparison of 8 intron positions in mouse and human reelin genes reveals a highly conserved genomic structure, suggesting a similar structure of the whole gene in both species. We identified two transcription start sites embedded within a CpG. The promoter region contains putative recognition sites for the transcription factors Sp1 and AP2 but lacks TATA and CAAT boxes. The presence of tandemly repeated regions in the Reelin protein suggests that gene duplication events occurred during evolution. By comparison of the amino acid sequences of the eight repeats and the positions of introns, we suggest a model for the evolution of the repeat coding portion of the reelin gene from a putative ancestral minigene.

Alternative Splicing↗

PubMed1982

DNA sequence organization of IS10-right of Tn10 and comparison with IS10-left.

Tn10 is 9,300 base pairs long and has inverted repeats of an insertion sequence (IS)-like sequence (IS10) at its ends. IS10-right provides all of the Tn10-encoded functions used for normal Tn10 transposition. IS10-left can also provide these functions but at a much reduced level. We report here the complete nucleotide sequence of IS10-right and a partial sequence of IS10-left. From our analysis of this information, we draw the following conclusions. (i) IS10-right is 1,329 base pairs long. Like most IS elements, it has short (23-base pair) nearly perfect inverted repeats at its termini. We can divide these 23-base pair segments into at least two functionally distinct parts. IS10-right also shares with other elements the presence of a single long coding region that extends the entire length of the element. Genetic evidence suggests that this coding region specifies an essential IS10 transposition function. A second, overlapping, coding region may or may not be important. (ii) The "outside" end of IS10-right contains three suggestively positioned internal symmetries. Two of these (A1 and A2) are nearly identical in sequence. Symmetry A1 overlaps the terminal inverted repeat; symmetry A2 overlaps the promoter shown elsewhere to be responsible for expression of IS10 functions and lies very near a second characterized promoter that directs transcription outward across the end of IS10. Symmetries A1 and A2 may play a role in modulation of Tn10 activity and are likely to function at least in part as protein recognition sites. We propose that the third symmetry (B) acts to prevent fortuitous expression of IS10 functions from external promoters. The transcripts from such promoters can assume a stable secondary structure in which the AUG start codon of the long coding region is sequestered in a region of double-stranded mRNA formed by pairing between the two halves of symmetry B. (iii) IS10-left differs from IS10-right at many nucleotide positions in both the presumptive regulatory region and the long coding region. The available evidence suggests that Tn10 may be older than other analyzed drug-resistance transposons and thus have had more time to accumulate mutational changes.

Base Composition↗

PubMed2004

Chemical biology of the sugar code.

A high-density coding system is essential to allow cells to communicate efficiently and swiftly through complex surface interactions. All the structural requirements for forming a wide array of signals with a system of minimal size are met by oligomers of carbohydrates. These molecules surpass amino acids and nucleotides by far in information-storing capacity and serve as ligands in biorecognition processes for the transfer of information. The results of work aiming to reveal the intricate ways in which oligosaccharide determinants of cellular glycoconjugates interact with tissue lectins and thereby trigger multifarious cellular responses (e.g. in adhesion or growth regulation) are teaching amazing lessons about the range of finely tuned activities involved. The ability of enzymes to generate an enormous diversity of biochemical signals is matched by receptor proteins (lectins), which are equally elaborate. The multiformity of lectins ensures accurate signal decoding and transmission. The exquisite refinement of both sides of the protein-carbohydrate recognition system turns the structural complexity of glycans--a demanding but essentially mastered problem for analytical chemistry--into a biochemical virtue. The emerging medical importance of protein-carbohydrate recognition, for example in combating infection and the spread of tumors or in targeting drugs, also explains why this interaction system is no longer below industrial radarscopes. Our review sketches the concept of the sugar code, with a solid description of the historical background. We also place emphasis on a distinctive feature of the code, that is, the potential of a carbohydrate ligand to adopt various defined shapes, each with its own particular ligand properties (differential conformer selection). Proper consideration of the structure and shape of the ligand enables us to envision the chemical design of potent binding partners for a target (in lectin-mediated drug delivery) or ways to block lectins of medical importance (in infection, tumor spread, or inflammation).

Binding Sites↗

PubMed1993

The role of attention for the Simon effect.

It has been claimed that spatial attention plays a decisive role in the effect of irrelevant spatial stimulus-response correspondence (i.e., the Simon effect), especially the way the attentional focus is moved onto the stimulus (lateral shifting rather than zooming). This attentional-movement hypothesis is contrasted with a referential-coding hypothesis, according to which spatial stimulus coding depends on the availability of frames or objects of reference rather than on certain attentional movements. In six experiments, reference objects were made available to aid spatial coding, which either appeared simultaneously with the stimulus (Experiments 1-3), or were continuously visible (Experiments 4-6). In contrast to previous experiments and to the attentional predictions, the Simon effect occurred even though the stimuli were precued by large frames surrounding both possible stimulus positions (Experiment 1), even when the reference object's salience was markedly reduced (Experiment 2), or when the precueing frames were made more informative (Experiment 3). Furthermore, it was found that the Simon effect is not reduced by spatial correspondence between an uninformative spatial precue and the stimulus (Experiment 4), and it does not depend on the location of spatial precues appearing to the left or right of both possible stimulus locations (Experiment 5). This was true even when the precue was made task-relevant in order to ensure attentional focusing (Experiment 6). In sum, it is shown that the Simon effect does not depend on the kind of attentional operation presumably performed to focus onto the stimulus. It is argued that the available data are consistent with a coding approach to the Simon effect which, however, needs to be developed to be more precise as to the conditions for spatial stimulus coding.

Adult↗

PubMed2005

What causes residual dual-task interference after practice?

Practice can dramatically reduce dual-task interference, but typically does not eliminate interference entirely. Residual interference after practice is especially large with certain non-preferred modality pairings (e.g., auditory-manual and visual-vocal). Does this residual interference imply the existence of a persistent central-processing bottleneck? To address this question, we transferred participants with previous dual-task practice to a psychological refractory period design. Although we observed residual dual-task costs in all four experiments, there was no evidence for a bottleneck, even with non-preferred modality pairings. We conclude that practice can eliminate the bottleneck limitation, but performance is still subject to other sources of interference, such as competition between central codes of the two tasks.

Adolescent↗

PubMed2007

Looks aren't everything: pseudohomophones prime words but nonwords do not.

After examining literature that deals with phonological and orthographic effects associated with pseudohomophones, the current effort deviates from the norm by using fewer pseudohomophones (20%) and extending the lags between primes and targets (M = 8). Word and pseudohomophone primes were found to facilitate lexical decision response latencies to word targets. Response latencies to word targets were not influenced by nonword primes, however. The presence of pseudohomophone effects was demonstrated by longer response latencies and higher error rates for pseudohomophones (e.g., DREEM) that were equated in orthography to nonword controls (e.g., DROAM). Despite the frequency effect observed for base words, the pseudohomophones did not exhibit an effect of base word frequency. The results suggest that phonological codes exert an influence on lexical representation but are not frequency sensitive.

Humans↗

PubMedDate not supplied

The impact of semantic transparency of morphologically complex words on picture naming.

We examined the contribution of semantic similarity to morphological priming effects, using the immediate (Exp. 1 and 3) and the delayed variant (Exp. 2) of picture-word interference. Distractor words were either compounds morphologically related to the picture name, but differing with respect to their semantic transparency (hummingbird, jailbird (Exp. 1); butterfly, butter dish (Exp. 3)), or form-related non-compound words (e.g., trombone). All three experiments revealed strong facilitation of picture naming due to morphologically related distractors. Form-related distractors facilitated picture naming in the immediate variant only, and to a lesser degree than compounds. Interestingly, the size of the morphemic effect was almost identical for semantically transparent and opaque complex words, which suggests that they share morphemic representations. These results suggest that morphological complexity in speech production is coded at the level of form representations, independent of semantic transparency.

Humans↗

PubMed1983

Visual and phonetic codes and the process of generation in letter matching.

Physically identical letter pairs are matched more quickly than are nominally identical or nonidentical pairs, which is an effect usually interpreted as resulting from the use of a visual memory code versus a phonetic or name code. However, prior manipulations of phonetic confusion and visual-field lateralization have provided little evidence consistent with this notion. Here, three reaction time experiments suggest through converging confusion and visual-field manipulations that a phonetic code is not used in either simultaneous or successive letter matching. Two additional experiments yield confusion evidence consistent with a rapid visual generation process underlying nominally identical and nonidentical matches, emphasizing the role of visual memory processes in all of the commonly used same-different letter-matching tasks. Implications for coding and hemispheric theories are discussed.

Form Perception↗