PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “recognition code”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed1989

Immunogenetic studies of spontaneous abortion in mice. III. Non-H-2 antigens and gestation.

CBA/J (H-2k) females, mated with DBA/2 J (H-2d) or DBA/1 J (H-2q) males, exhibit a high rate of fetal resorption. In contrast, when H-2 identical CBA substrains (i.e. CBA/Ca and CBA/N) are used, this phenomenon is not observed. On the other hand, before mating with DBA/2 J males, pre-immunization of CBA/J females with spleen cells coming from BALB/c J or (DBA/2 x BALB/c J) F1 males (and not from other H-2d identical males whatever their Mls alleles) has significantly decreased the fetal resorption rate. Thus, immunization against determinants other than classical H-2d (K, I, D, L) antigens (transmitted as a dominant character and different from Mls determinants) can elicit anti-abortive effects. Furthermore, it was observed that the spleen cell endowed with the anti-abortive effects was neither a T nor a B lymphocyte. In contrast, peritoneal cells were able to reproduce the phenomenon, indicating that it may be mediated by a cell of the macrophage-monocyte lineage. Finally, a first gestation was substituted for allo-immunization of CBA/J females. The anti-abortive effects of a first pregnancy by BALB/c J males (and not by other H-2k syngeneic or H-2d allogeneic males) was observed in the course of a second pregnancy sired by DBA/2 J males. These data can be interpreted in terms of maternal recognition of an antigen present on both macrophages and trophoblast cells and necessary for a successful gestation, which is coded for by genes outside the K, I, D, L regions.

Abortion, Veterinary↗
PubMedDate not supplied

Acoustic and electrical pattern analysis of consonant perceptual cues used by cochlear implant users.

It is hypothesized that for postlingually deafened adult cochlear implant (CI) users, a significant source of their perceptual performance variability is attributable to differences in their ability to discriminate the basic perceptual cues that are important in speech recognition. Previous research on 'electric hearing' has identified consistent perceptual cues for vowel recognition. However, the results on consonant perception by CI users are less clear. The primary purpose of this study is to present a quantitative method of evaluating potential 'electric cues' used by CI users in consonant identification. Since the actual input signals to the auditory periphery of CI users are electric in nature, we elected to measure the CI electric discharge patterns in addition to the original acoustic waveforms. The characteristics of the electric discharge patterns in response to intervocalic consonants were quantified and correlated with the dimensions of CI patients' perceptual spaces, which were computed from multidimensional scaling analyses of their consonant confusion matrices. The results agree with most, but not all, commonly accepted acoustic cues used by normal-hearing listeners. The correlation findings also suggest that CI users employ different sets of 'electric cues' in perceiving consonants that differ in their manner of articulation. Specifically, spectral and temporal cues associated with slowly changing formant structures and transitions, and features associated with frication and high-frequency noise, are all highly correlated with the perceptual dimensions of all CI users. However, rapidly changing formant transitions, such as those present in stop consonants, did not appear to play a significant role in consonant recognition by more poorly performing CI subjects. The perceptual results were consistent with our physical findings that the SPEAK coding strategy partially degraded the rapidly changing formant transitions.

Acoustic Stimulation↗
PubMed2006

"What" and "where" in word reading: ventral coding of written words revealed by parietal atrophy.

The visual system of literate adults develops a remarkable perceptual expertise for printed words. To delineate the aspects of this competence intrinsic to the occipitotemporal "what" pathway, we studied a patient with bilateral lesions of the occipitoparietal "where" pathway. Depending on critical geometric features of the display (rotation angle, letter spacing, mirror reversal, etc.), she switched from a good performance, when her intact ventral pathway was sufficient to encode words, to severely impaired reading, when her parietal lesions prevented the use of alternative reading strategies as a result of spatial and attentional impairments. In particular, reading was disrupted (a) by rotating word by more than 50 degrees , providing an approximation of the invariance range for words encoding in the ventral pathway; (b) by separating letters with double spaces, revealing the limits of letter grouping into perceptual wholes; (c) by mirror-reversing words, showing that words escape the default mirror-invariant representation of visual objects in the ventral pathway. Moreover, because of her parietal lesions, she was unable to discriminate mirror images of common objects, although she was excellent with reversible pseudowords, confirming that the breaking of mirror symmetry was intrinsic to the occipitotemporal cortex. Thus, charting the display conditions associated with preserved or impaired performance allowed us to infer properties of word coding in the normal ventral pathway and to delineate the roles of the parietal lobes in single-word recognition.

Cerebral Cortex↗
PubMedDate not supplied

[Prevention of habitual abortion by buffycoat transfusions].

From an immunological point of view the product of pregnancy may be regarded as a haplo-different allotransplant. A system possibly closely linked to the HLA-region is postulated to lead to the immunological recognition of the fetus by the mother and, paradoxically, to a take of the "transplant". The postulated system apparently codes for antigens present on both trophoblast and adult lymphocytes (TLX = trophoblast-lymphocyte-crossreacting). The prevention of rejection is thought to be effected by blocking factors (BF) present in the serum or plasma of the mother. There may be different kinds of BF: a specific BF (detectable only in an autologous assay system), appearing late in pregnancy, which inhibits several lymphocyte-dependent reactions (e.g. production of MIF, MLC). This BF has been identified as an IgG-class antibody. a nonspecific BF, appearing early in pregnancy which inhibits the MLC in vitro. c) may be a third BF, also specific, which is found only in plasma but not in serum. All described BF-activities were absent in women with habitual abortions. HLA-identity or partial identity could imply TLX-identity. The consequence of such an identity could be: non-detection of the trophoblast by the immune system of the mother, no production of BF, abortion. However several investigators could not find any HLA-identity of the partners with habitual abortions. A protective effect on the fetus has been seen when pregnant women were immunised with adult leukocytes, using either buffycoats from various HLA-different but bloodgroup-compatible donors or isolated leukocytes from the spouse.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Habitual↗
PubMed1997

Immunochemical localization of the phylogenetically oldest receptor tyrosine kinase: existence in the marine sponge Geodia cydonium.

Until now molecular data, elucidating the basis of invertebrate immunity are lacking. Previously both the gene and different cDNAs, coding for the ancestor of metazoan receptor tyrosine kinases (RTK), have been isolated from the marine sponge Geodia cydonium. The sponge RTK shows high polymorphism in the coding as well as in the non-coding parts of the gene. To further elucidate if the sponge RTK might be a molecule involved in self/non-self recognition the intracellular portion of the sponge RTK was expressed in Escherichia coli. The 59 kDa recombinant protein was used to raise monoclonal antibodies (McAb). The McAb recognized three polypeptides of sizes 135, 68 and 26 kDa by Western blotting. The McAb recognized only the plasma membranes of sponge cells as analyzed by immunohisto- and cytochemical studies. Northern blotting analysis revealed that the expression of the RTK gene depends on environmental conditions and on seasonal variations. Based on the high degree of polymorphism and on the immunochemical data we suggest that the RTK in G. cydonium might be involved in sponge immunity.

Animals↗
PubMed1998

[Polymorphism of the gene of heat shock protein hsp70 in lines of rats with normal and hypertensive status].

RFLP in the hsp70 gene encoding a major heat shock protein was analyzed in rat strains with high and normal arterial blood pressure. Dimorphism in the sets of DNA fragments was revealed after hybridization of the hsp gene leader sequence with rat DNA digested with BamHI restriction endonuclease. Type I RFLP was represented by the fragments of 12,200, 6500, 41,000 and 1600 bp in size. Type II RFLP corresponded to the set that included the fragments of 12,200, 6500, 2900, 1600, and 1200 bp in size. Interstrain polymorphism was demonstrated for the fragments of 4100, 2900 and 1200 bp. Furthermore, analysis of different rat strains showed that the 2900- and 1200-bp fragments were linked and formed by cleavage of the 4100-bp fragment with restriction endonuclease. This polymorphism was probably caused by the point A-->T mutation occurring in the BamHI recognition site located in the leader sequence of the hsp70 gene at a distance of +35 bp from the coding sequence. Examination of interstrain RFLP in the hsp70 gene indicated that the presence of 2900-bp fragment was not associated with hypertensive status in all experimental models of inherited arterial hypertension. This confirms the assumption on genetic heterogeneity of this common disease.

Animals↗
PubMed2002

Reduced-median-network analysis of complete mitochondrial DNA coding-region sequences for the major African, Asian, and European haplogroups.

The evolution of the human mitochondrial genome is characterized by the emergence of ethnically distinct lineages or haplogroups. Nine European, seven Asian (including Native American), and three African mitochondrial DNA (mtDNA) haplogroups have been identified previously on the basis of the presence or absence of a relatively small number of restriction-enzyme recognition sites or on the basis of nucleotide sequences of the D-loop region. We have used reduced-median-network approaches to analyze 560 complete European, Asian, and African mtDNA coding-region sequences from unrelated individuals to develop a more complete understanding of sequence diversity both within and between haplogroups. A total of 497 haplogroup-associated polymorphisms were identified, 323 (65%) of which were associated with one haplogroup and 174 (35%) of which were associated with two or more haplogroups. Approximately one-half of these polymorphisms are reported for the first time here. Our results confirm and substantially extend the phylogenetic relationships among mitochondrial genomes described elsewhere from the major human ethnic groups. Another important result is that there were numerous instances both of parallel mutations at the same site and of reversion (i.e., homoplasy). It is likely that homoplasy in the coding region will confound evolutionary analysis of small sequence sets. By a linkage-disequilibrium approach, additional evidence for the absence of human mtDNA recombination is presented here.

Africa↗
PubMed1996

The hypercube structure of the genetic code explains conservative and non-conservative aminoacid substitutions in vivo and in vitro.

A representation of the genetic code as a six-dimensional Boolean hypercube is described. This structure is the result of the hierarchical order of the interaction energies of the bases in codon-anticodon recognition. In this paper it is applied to study molecular evolution in vivo and in vitro. In the first case we compared aligned positions in homologous protein sequences and found two different behaviors: (a) There are sites in which the different amino acids may be explained by one or two 'attractor nodes' (coding for the dominating amino acid(s)) and their one-bit neighbors in the codon hypercube; and (b) There are sites in which the amino acids correspond to codons located in closed paths in the hypercube. In the second case we studied the 'Sexual PCR'1 experiment described by Stemmer [Stemmer (1994)] and found that the success of this combination of usual PCR and recombination is in part due to the Gray code structure of the genetic code.

Amino Acids↗
PubMed1991

How the sheep's brain controls the visual recognition of animals and humans.

Visual recognition of objects and individuals is important for humans and many animal species. How does the brain process such visual information and how does experience modify such processing? To answer these questions we have used single-cell, electrophysiological recording techniques to investigate the responses of single neurons in the temporal cortex of the brain of the conscious sheep to visual images of animals and humans. Results show that a small population of these cells responds (latencies less than 180 ms) specifically to projected images of animal and human faces. Different cells respond to 1) faces with horns, and how large the horns are; 2) faces of sheep of the same breed, particularly to socially familiar individuals, and 3) faces of humans or dogs. In general, frontal views of faces (i.e., direct eye contact) are more effective stimuli than profiles or views of the back of the head. Some other cells in the temporal cortex respond to the sight of a human shape, rather than to the face. These latter cells are specialized for visual recognition of the human shape dependent on what actions are displayed (approaching or withdrawing figure), posture adopted (bipedal or quadrupedal), and view presented (front or side). These results provide important information on the complex neural processing of visual recognition of individuals by sheep and suggest that experience may modify sensory processing. Thus, behaviorally important, distinguishing features (such as horns), preferred individuals (socially familiar animals), and potentially threatening individuals (humans and sheep dogs) are specifically coded for, at a sensory level, so that appropriate behavioral or emotional responses can be made with the minimum delay.

Animals↗
PubMed2002

Two self-splicing group I introns in the ribonucleotide reductase large subunit gene of Staphylococcus aureus phage Twort.

We have recently described three group I introns inserted into a single gene, orf142, of the staphylococcal bacteriophage Twort and suggested the presence of at least two additional self-splicing introns in this phage genome. Here we report that two previously uncharacterized introns, 429 and 1087 nt in length, interrupt the Twort gene coding for the large subunit of ribonucleotide reductase (nrdE). Reverse transcription-polymerase chain reaction (RT-PCR) of RNA isolated from Staphylococcus aureus after phage infection indicates that the introns are removed from the primary transcript in vivo. Both nrdE introns show sequence similarity to the Twort orf142 introns I2 and I3, suggesting either a common origin of these introns or shuffling of intron structural elements. Intron 2 encodes a DNA endonuclease, I-TwoI, with similarity to homing endonucleases of the HNH family. Like I-HmuI and I-HmuII, intron-encoded HNH endonucleases in Bacillus subtilis phages SPO1 and SP82, I-TwoI nicks only one strand of its DNA recognition sequence. However, whereas I-HmuI and I-HmuII cleave the template strand in exon 2, I-TwoI cleaves the coding strand in exon 1. In each case, the 3' OH created on the cut strand is positioned to prime DNA synthesis towards the intron, suggesting that this reaction contributes to the mechanism of intron homing. Both nrdE introns are inserted in highly conserved regions of the ribonucleotide reductase gene, next to codons for functionally important residues.

Amino Acid Sequence↗
PubMed1990

Electrically evoked whole-nerve action potentials: data from human cochlear implant users.

This study describes a method for recording the electrically evoked, whole-nerve action potential (EAP) in users of the Ineraid cochlear implant. The method is an adaptation of one originally used by Charlet de Sauvage et al. [J. Acoust. Soc. Am. 73, 615-627 (1983)] in guinea pigs. The response, recorded from 11 subjects, consists of a single negative peak that occurs with a latency of approximately 0.4 ms. EAP input/output functions are steeply sloping and monotonic. Response amplitudes ranging up to 160 micro V have been recorded. Slope of the EAP input/output function correlates modestly (approximately 0.6-0.69) with results of tests measuring word recognition skills. The refractory properties of the auditory nerve were also assessed. Differences across subjects were found in the rate of recovery from the refractory state. These findings imply that there may be difference across subjects in the accuracy with which rapid temporal cues can be coded at the level of the auditory nerve. Reasonably strong correlations (approximately 0.74-0.85) have been found between the magnitude of the slope of these recovery curves and performance on tests of word recognition.

Cochlear Implants↗
PubMed1987

[Male-female recognition during sexual reproduction in flowering plants].

In flowering plants, the recognition reactions occur between male and female partners at the stigma level or along the style and in the embryo sac between the gametes. The study of these biological events implies to check the viability of the two partners. Interacting molecules are glycoproteins. A cDNA coding for the stigma protein molecules has recently been cloned. The specific pollen molecules have been also characterized. They are glycoproteins which are localized at the periphery of the grain and rapidly diffuse. These recognitive molecules present some analogies with pollen allergens.

Female↗
PubMed1982

Cell membrane polymorphisms coded for in the HLA-D/DR region. I. Relation between D and DR.

The relation of HLA-D and -DR determinants was studied in Dutch Caucasoids. The recognition of subgroups of DR4, DR5, and DR7, and the specificities LB12 and LB13 are described. Phenotype and gene frequencies and a Hardy--Weinberg analysis of DR and local (LB) B-cell groups are given. Excellent correlation between D and DR typing was obtained when HTCs were studied by selected B-cell antisera. When the same sera were used to type a panel of D typed cells, the correlation was decreased (with the exception of DR3 and Dw3). In the case of discrepancies the DR specificity, but not the corresponding D specificity, always could be found and not the other way around. The data fit best the assumption that HLA-D and -DR are carried by the same molecule, although they might be different determinants on this molecule. A number of possible explanations for the observed discrepancies has been given.

Cell Membrane↗
PubMed1994

The dynamics of Prägnanz.

There is quite wide-spread agreement about the relevance of pattern Prägnanz (Koffka, 1935) with respect to the human interpretation of visual patterns. There is less agreement about whether pattern Prägnanz is based solely on pattern information (static) or also on the history of the perceiver (dynamic). In Van Leeuwen and Van den Hof (1991), experimental data concerning serial patterns are presented within the framework of the dynamic-network approach initiated by Buffart (1986, 1987). These experimental data are claimed to give evidence against the static-coding approach initiated by Leeuwenberg (1969, 1971). In the present paper, however, I show first that Buffart's theoretical basis is incorrect, and that in fact Leeuwenberg's static-coding approach is the basis for the dynamic-network approach. Second, I show that those experimental data rather give evidence in favor of the static-coding approach, by using those same data for a test of the most recent static-coding model (Van der Helm & Leeuwenberg, 1991; Van der Helm, Van Lier, & Leeuwenberg, 1992). Finally, I propose a reconciliation between the two approaches, in the sense that the dynamic-network model could be shaped in such a way that it yields a simulation, and maybe even an enrichment, of the static-coding model.

Humans↗
PubMed1986

The basis of Stroop interference involving the multimodal correlates of auditory pitch.

A pure auditory tone has a range of multimodal qualities that are determined by its pitch. A reaction-time task was used to demonstrate that subjects respond immediately and automatically to these qualities. Subjects were required to press one of two keys depending on which word, from a limited set, appeared on a microcomputer screen. The words were antonyms that represented multimodal stimulus qualities, and they were assigned to alternative responses so that the two words that shared the same response were correlated in the same way with pitch. As an incidental stimulus, either a 50 Hz tone or a 5500 Hz tone accompanied the presentation of each word. Subjects were found to respond more slowly when the multimodal qualities of the tone were incongruent with the qualities represented by the test word. When the stimulus-response mapping rules were changed, however, the Stroop effect did not occur; suggesting that a polarised semantic code of the incidental tone, that embraces its multimodal features, accesses the same semantic register as the equivalent code for the test word itself.

Auditory Perception↗