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Results for “repetitive features”

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PubMed1991

A neurobehavioral syndrome after failure to thrive on chloride-deficient formula.

Eleven of 13 children, who demonstrated a failure-to-thrive pattern in infancy attributable to chloride-deficient Neo-Mull-Soy formula, had distinctive cognitive impairments four to nine years later. These included: a language disorder primarily involving articulation, word finding and naming; visual-motor and fine motor difficulties; and attention deficit disorder, often featuring repetitive behaviours, withdrawal and perseveration ('overfocus'). In contrast, global intellectual abilities were within the normal range in all 11 children. This residual neurobehavioral syndrome is too rare in the developmentally disabled population to reflect a chance association. It has not been associated either with protein-calorie malnutrition or chloride-deficiency diseases.

Body Height↗

PubMed1996

Intensive oral methotrexate protects against lymphoid marrow relapse in childhood B-precursor acute lymphoblastic leukemia.

PURPOSE: To describe the use of combination chemotherapy, including divided-dose oral methotrexate (dMTX), for children with B-precursor acute lymphoblastic leukemia (ALL). dMTX produced prolonged MTX exposure on an outpatient basis. PATIENTS AND METHODS: Two hundred forty-three patients were treated from January 1986 to May 1992. dMTX was given weekly during consolidation and biweekly for the first 16 months of continuation therapy with mercaptopurine (6-MP) and asparaginase (L-ASP). Initially, etoposide (VP-16) and cytarabine (Ara-C) pulses were included. Treatment continued for 30 months with single-dose weekly MTX replacing dMTX during continuation, part 2. Unexpected acute neurotoxicity was eliminated by the addition of leucovorin. VP-16 and Ara-C were omitted in the face of acute myelogenous leukemia (AML). RESULTS: Two hundred thirty-nine patients entered remission: 16 had a lymphoid marrow relapse, two each with testicular or CNS relapse; 19 a CNS relapse; 16 secondary AML; three other second malignancies; two withdrew for transplant; three died in remission; 16 withdrew because of noncompliance, and nine withdrew with toxicity. Event-free survival (EFS) at 4 years was 73 +/- 4%; 81 +/- 4% for 150 patients with better risk features and 60 +/- 7% for 93 with high-risk features. Lymphoid marrow relapse-free survival in the standard- and high-risk patients was 94 +/- 3% and 86% +/- 6%, respectively. The most common adverse event was secondary AML in the standard-risk group and isolated CNS relapse in the high-risk group. CONCLUSION: This therapy produced an overall EFS similar to other published regimens, but the pattern of failures is very different, with few patients having a lymphoid marrow relapse. These data suggest that highly effective therapy for children with ALL can be delivered on an outpatient basis using a regimen featuring repetitive dMTX.

Administration, Oral↗

PubMed2005

Category-related brain activity to natural categories is associated with the retrieval of visual features: Evidence from repetition effects during visual and functional judgments.

It is debated whether category-related brain activation reflects a modality-specific (e.g., visual, functional representation systems) or a domain-specific (e.g., natural vs. artifactual categories) semantic memory organization. The present event-related potentials (ERPs) study is aimed at elucidating the nature of semantic representations of objects from natural (e.g., animal) and artifactual (e.g., tool) categories. Within a repetition priming paradigm, we tested the assumption that modality-specific semantic systems are differentially involved in representing artifacts and natural kinds by probing either visual or functional knowledge in a test task. In the exposure phase, subjects performed a classification task on object names for artifacts and natural objects. In the test phase, these previously presented (old) names were presented together with new names, and subjects had to perform either a visual (shape) or a functional (use) judgment. As in previous ERP studies, words from natural categories were associated with a more positive potential at occipito-parietal electrodes than words from artifactual categories. This effect was only obtained during the visual judgment task. This category-related ERP effect was diminished for words that had been previously presented. In the functional judgment task, category-related ERP effects were not obtained at all, probably due to the heterogeneity of the probed features. The observed interaction between task, category and repetition provides direct evidence that visual features play a more important role for the representations of natural compared to artifactual categories. Our data are therefore compatible with the notion of modality-specific semantic systems.

Adult↗

PubMed1993

Wide dynamic range but not nociceptive-specific neurons encode multidimensional features of prolonged repetitive heat pain.

1. To better characterize temporal and spatial mechanisms involved in the coding of prolonged nociceptive stimuli in the spinal cord, the responses of dorsal horn wide dynamic range (WDR) and nociceptive-specific (NS) neurons to prolonged, repetitive noxious heat stimuli (45-49 degrees C) were examined in unanesthetized, spinal cord transected rats. To relate these neuronal responses to conscious dimensions of pain, human subjects were presented with identical types of prolonged, repetitive stimuli, so that psychophysical ratings of pain intensity and pain unpleasantness could be compared with the magnitudes and temporal features of the responses of NS and WDR neurons. 2. WDR neurons exhibited high rates of impulse discharge throughout 45 min of repetitive nociceptive stimulation, with only partial reduction (31% decrease from peak rates) occurring after 2 min of stimulation. In sharp contrast, NS neurons stimulated under the same conditions displayed substantial reduction of firing (73% decrease from peak rates) after a brief, initial period of activity that occurred within 2 min after onset of stimulation. Psychophysical ratings of pain intensity and pain unpleasantness, like the responses of WDR neurons, did not decrease substantially from initial levels during 7 min of painful stimulation. Furthermore, these ratings remained at high levels during time periods where the impulse frequencies of NS neurons were only at 27% of maximal levels. 3. Graded nociceptive stimuli were employed to characterize the ability of WDR neurons to encode nociceptive intensity over long durations of repetitive stimulation and to delineate further the relationship between WDR and psychophysical responses. Both WDR discharge frequencies and psychophysical ratings of pain intensity and unpleasantness increased in a monotonic manner to graded increases in stimulus temperatures. 4. These results indicate that pain does not decrease substantially during the course of prolonged, repetitive nociceptive stimulation. The fact that the responses of NS neurons decline significantly, whereas both WDR and psychophysical responses do not, suggests that WDR neurons alone are sufficient to evoke both sensory intensity and affective responses to prolonged pain. Furthermore, because subjects could localize and qualitatively describe pain at times when responses of NS neurons were minimal, WDR neurons alone can encode some spatial and qualitative aspects of pain.

Adult↗

PubMed1999

Structural bistability of repetitive DNA elements featuring CA/TG dinucleotide steps and mode of evolution of satellite DNA.

Satellite DNA sequences are known to be important components required for the construction of centromeres and are common to all higher eukaryotes. Nevertheless, their nucleotide sequences vary significantly, even in evolutionarily related species. In order to elucidate how the nucleotide sequences define the conformational character of centromeric satellite DNA, an evolutionary path toward repetitive units has been hypothesized. In that context, the DNA conformation of fish satellite DNA was evaluated in two ways: the organization of subrepeats and sequence characteristics were compared, and the differences in stacking energies between A-helix and B-helix and the sequence-dependent bendability of the helices were evaluated. Our findings suggest that the monomeric units making up currently observed repetitive sequences have evolved through stepwise amplification of shorter, ancestral sequences by increasing the length of the units. In addition, we suggest that potentially key sequences required for DNA amplification comprise highly flexible structures. Thus flexibility of the DNA structure may be a primary prerequisite for DNA amplification.

Animals↗

PubMedDate not supplied

Repetitive behaviors in autism: relationships with associated clinical features.

Relationships between repetitive behaviors (RBs) and associated clinical features (i.e., cognitive and adaptive functioning levels, sleep problems, medication use, and other behavioral problems) were examined in two groups (High nonverbal IQ > or = 97 versus Low nonverbal IQ < or = 56) of children with autism spectrum disorders (n = 14; mean age = 10 years, 7 months). For the group as a whole, nonverbal cognitive ability (NVIQ) (as measured by the Leiter-R), adaptive functioning level, the presence of sleep problems, and three scales of the Aberrant Behavior Checklist (ABC) (Irritability, Lethargy, and Hyperactivity) were highly correlated with total RB scores on the Repetitive Behavior Scale-Revised (RBS-R). After controlling for NVIQ, adaptive level, sleep problems, and two scales of the ABC (Irritability and Lethargy) were not significantly associated with RB scores. However, there remained a significant positive correlation between the presence of RBs and the Hyperactivity scale of the ABC. Parent ratings of their stress levels and the presence of RBs in their children were highly correlated. The relationship between RBs and associated clinical features in autism is complex and future studies should control for cognitive ability when examining the direct and indirect relationships of these variables with RBs.

Adaptation, Psychological↗

PubMed1994

[Repetitive monomorphic ventricular tachycardia].

PURPOSE: To evaluate retrospectively clinical features of repetitive monomorphic ventricular tachycardia (RMVT). METHODS: Files of 11 patients with RMVT were analyzed (9 females, mean-age 37 +/- 17 years). All patients were submitted to clinical evaluation, ECG, Holter monitoring stress test, high-resolution ECG and echocardiogram; they were treated with antiarrhythmic drugs. RESULTS: Patients were in NYHA class I or II, 9 asymptomatics and 2 with palpitations. The ECG was normal in all of them. Cardiac memory was observed in 3. A left bundle branch block with inferior axis deviation in the frontal plane was present during RMVT in all patients (right ventricular outflow tract focus). Holter monitoring revealed mean of 12031 +/- 8345 isolated PVC/24h; 2892 +/- 234 ventricular couplets/24h and 1367 +/- 890 VTs/24h (mainly nonsustained). In 6 patients RMVT was suppressed during maximal exercise treadmill. High-resolution ECG was negative in all group. Five patients had a normal echocardiogram while 5 showed mitral valve prolapse. One patient developed tachycardiomyopathy. The arrhythmia was controlled with 320mg of oral sotalol in 3 of 4 that used this drug and with 120mg oral propranolol in one of 6 that used this drug. Drug resistance was present in the others. The mean follow-up period was 38 +/- 16 months. CONCLUSION: The results demonstrate that RMVT is a benign form of VT with no detectable anatomic substract by the currently used methods. It is probably induced by nonreentrant mechanism and frequently drug resistance is observed. Among the antiarrhythmic drugs commonly used, sotalol showed to be the most effective.

Adult↗

PubMed2005

Expectation and repetition effects in searching for featural singletons in very brief displays.

We studied the effects of expectation and repetition on searching for singletons in very brief displays. In Experiment 1, we found that when a given feature defined the singleton for a whole block--so that in every trial the subject could expect a particular target feature--search accuracy was significantly higher than when the feature setting was randomly redetermined from trial to trial. However, an unexpected repetition triggered almost no advantage. In Experiment 2, we found no advantage for expected alternation. Experiments 3 and 4 demonstrated that there is little or no advantage for perception in conditions allowing only for target-feature facilitation or distractor-feature inhibition. We propose that in singleton search a division of feature space facilitates detection, and that this division works best under conditions of expected repetition. Experiment 5 replicated Experiment 1, but in Experiment 5 we examined response times and long display exposures. Results suggested that previous findings of singleton priming reflect mainly postperceptual factors.

Attention↗

PubMed2002

Priming in macaque frontal cortex during popout visual search: feature-based facilitation and location-based inhibition of return.

In popout search, humans and monkeys are affected by trial-to-trial changes in stimulus features and target location. The neuronal mechanisms underlying such sequential effects have not been examined. Single neurons were recorded in the frontal eye field (FEF) of monkeys performing a popout search during which stimulus features and target position changed unpredictably across trials. Like previous studies, repetition of stimulus features improved performance. This feature-based facilitation of return was manifested in the target discrimination process in FEF: neurons discriminated the target from distractors earlier and better with repetition of stimulus features, corresponding to improvements in saccade latency and accuracy, respectively. The neuronal target selection was mediated by both target enhancement and distractor suppression. In contrast to the repetition of features, repetition of target position increased saccade latency. This location-based inhibition of return was reflected in the neuronal discrimination process but not in the baseline activity in FEF. These results show adjustments of the target selection process in FEF corresponding to and therefore possibly contributing to changes in performance across trials caused by sequential regularities in display properties.

Action Potentials↗

PubMed1990

Stimulus repetition effects and the dimension-feature distinction in alternative targets.

The negative repetition effect (NRE) refers to a poorer perception of the target in noise-same-as-target than in noise-alternative-target displays. Using the parenthesis as target and noise that are either identical or different in orientation, we tested predictions derived from a feature-specific inhibition model (Bjork & Murray, 1977) that explains the NRE as arising from inhibitory interactions among channels handling identical inputs. Contrary to our expectation of evidence for orientation-specific inhibition, a positive repetition effect (PRE) was observed. We also found a PRE for the dimension target sets whose stimuli differ only in orientation and an NRE for the feature target sets whose stimuli differ in the number of elements. Further experiments that systematically varied relationships between alternative targets indicate that these basic findings, termed the stimulus attributes effects, do not arise from pattern masking, perceptual strategies, or response bias.

Adult↗

PubMed2006

Sequential modulations of interference evoked by processing task-irrelevant stimulus features.

Compatibility level repetition benefits in interference paradigms have been taken to reflect enhanced processing selectivity in response to cognitive conflict elicited by a task-irrelevant stimulus feature. The authors demonstrate such sequential effects in the Simon task which (a) occur independent of previous behavioral conflict effects and (b) cannot be accounted for by selectivity enhancement. Furthermore, when presenting more than one type of irrelevant stimulus features, compatibility level repetition effects occurred in a type-specific manner. The results do not support the notion that cognitive conflict results in enhanced processing selectivity and favor a feature integration account.

Adult↗

PubMed1994

Melancholic symptom features and DSM-IV.

OBJECTIVE: The purpose of this article is to provide an overview of existing systems for the diagnosis of the endogenous (melancholic) subtype of major depression. METHOD: The authors review the critical empirical research examining this subtype and discuss its implications for DSM-IV. They examine the relationship of endogenous/melancholic symptoms to other clinical features, treatment response, selected laboratory tests, consistency across episodes, family history, and particular courses of illness. RESULTS: Melancholic symptom features are predictive of a positive response to ECT and to tricyclic antidepressants in the severely ill. Key features include psychomotor retardation, unreactive mood, pervasive anhedonia, and distinct quality of mood. Melancholic features are associated with shorter REM latency and/or nonsuppression of cortisol during the dexamethasone suppression test. Depressive episodes that are not melancholic may take on melancholic features with repetition and passage of time in some individuals. Once melancholic features are present, it is unclear whether they repeat across subsequent episodes. Melancholic features are not uniquely associated with a positive family history of depression per se, but they may be especially associated with a family history of severe depression. CONCLUSIONS: The available evidence suggests some clinical utility and some (albeit not entirely consistent) validity for the concept of melancholic features. Consequently, DSM-IV will retain the designation "with melancholic features," return to the shorter DSM-III feature listing, and broaden the designation by requiring either unreactive mood or pervasive anhedonia but not both. Further research on this subgroup is indicated.

Depressive Disorder↗

PubMed1987

Impoverished written responses and negative features of schizophrenia.

Repetition in the written language of schizophrenics and its possible relationships to other aspects of schizophrenic disorders are not well understood. We investigated repetitiousness in written utterances, finding schizophrenic subjects to be more repetitive than affective controls and normal controls. Over-all, written repetitiousness was more strongly correlated with psychopathologic features than oral repetitiousness. As in previous work, thought-disordered schizophrenic subjects produced the most repetitive responses. Poverty of content and illogical thinking were correlated with scores for written repetition. Measures of other negative features, disturbed mental functioning and motor behavior were also associated with repetitiousness in both written and oral modes. That these negative features are linked (namely, linguistic repetitiousness, negative formal thought disorder, voluntary motor abnormalities, and deficient mental functioning) is consistent with Crow's concept of a defect syndrome (Type 2) in schizophrenia.

Humans↗

PubMed1976

[Work load due to stamping task as a simple repetitive hand work (author's transl)].

An experimental study was carried out on stamping task using no conveyers with short work cycle which was taken as featuring simple repetitive hand work. Each phase of this work was allowed to each subject. Seventeen healthy adults, 8 males and 9 females, were engaged in the 120 minutes, stamping task. They were tested by their function of concentration maintenance (TAF), by flicker frequency and 30 items of subjective symptoms as advocated by the Japan Association of Industrial Health. Quantities of work for each 10 minutes were calculated. The results obtained were as follows: 1) Number of stamped cards by male subjects was more than that by female subjects. 2) Pace of work performance in the female subjects was being kept more in balance with their capacity in comparison with the male subjects. 3) The results of TAF and FF tests showed that the body load in the male subjects were greater than in the female subjects.

Adult↗

PubMed1986

The present status of erythrocyte spectrin structure: the 106-residue repetitive structure is a basic feature of an entire class of proteins.

Spectrin, the major component of the erythroid membrane skeleton, is a long, asymmetrical rodlike protein that interacts with several other proteins to form a two-dimensional membrane skeleton. Progress in several laboratories over the past few years including substantial partial peptide and nucleotide sequence determination has greatly enhanced our knowledge of the structural properties of this large molecule (heterodimer = 465,000 daltons). The alpha and beta subunits are homologous with approximately 30% identity. They are aligned in an antiparallel side-to-side orientation with the amino- and carboxy-termini near opposite physical ends of the molecule. The predominant structural feature elucidated from sequencing this large molecule is the nearly universal occurrence in both subunits of a single type of repetitive structure. The periodicity of this homologous structure is exactly 106 amino acid residues. As many as 36 homologous, but nonidentical, repeats exist and comprise more than 90% of the mass of the heterodimer. Each of these repetitive units is folded into a triple-stranded structure that is highly helical. Peptide maps, antibody crossreactivity, peptide sequence analysis, and more recently nucleic acid sequences have defined several major properties of the erythroid molecule and related proteins in other tissues. Tissue-specific spectrins have the same 106-residue repetitive structure and show sequence homology to erythroid spectrin.

Amino Acid Sequence↗

PubMed1988

Software systems to control sensitivity studies of Monte Carlo simulation models.

Studies of the sensitivity of Monte Carlo models to changes in the values of their features involve repetitive simulations. Subsequent displays and analyses express variation in simulated outcomes as a function of change in location in multidimensional feature space and provide feedback via inputs for future simulations. A software system has been designed to control execution of the interacting programs required, reducing the need for human intervention. Assumptions about the goals and operation of the system as a whole are isolated within a program which executes component packages using interprogram control and communication mechanisms. The latter allow component programs to operate independently of the sources of data or the execution environment: they may be used separately, or in software systems, such as for sensitivity analysis of a Monte Carlo epidemic model. The methodology contributes to modularity at the level of executable programs and to the plausibility and efficiency of sensitivity studies.

Computer Simulation↗

PubMed1982

Molecular characterization of small polydisperse circular deoxyribonucleic acid from an African green monkey cell line.

Several size classes of small polydisperse circular (spc) DNA from the African green monkey cell line BSC1 have been cloned into the bacterial plasmid pBR322. Analysis of the cloned spc DNA fragments as well as total spc DNA reveals that (a) most or all cloned spc DNAs share homologies with chromosomal sequences, (b) both unique and repetitive chromosomal sequences are represented in spc DNA, (c) the repetitive sequences in spc DNA include two known major repeat families (the alpha and the Alu) as well as a third, as yet unidentified, set of interspersed repetitive sequences, and (d) the alpha-like sequences are present in an oligomeric series of circular DNA molecules within the spc DNA population. The organizational features of repetitive DNA sequence-carrying circles suggest a mechanism for their generation.

Animals↗

PubMed1997

Humero-spinal dysostosis: report of the fourth case with emphasis on generalized skeletal involvement, abnormal craniofacial features, and mitral valve thickening.

The fourth reported case of humero-spinal dysostosis is notable in that (a) it confirms the unique combination of bifid distal humeri and coronal clefts, (b) involves a third unique feature as being mitral valve thickening. (c) suggests a more generalized involvement of bone in the form of a dysplasia, and (d) raises the possibility of repetitive craniofacial features.

Abnormalities, Multiple↗