SEARCH · PubMed Health

Results for “repetitive features”

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 19 recordsLinked to original sources

PubMed2024

Ribosomal DNA copy number variation associates with hematological profiles and renal function in the UK Biobank.

The phenotypic impact of genetic variation of repetitive features in the human genome is currently understudied. One such feature is the multi-copy 47S ribosomal DNA (rDNA) that codes for rRNA components of the ribosome. Here, we present an analysis of rDNA copy number (CN) variation in the UK Biobank (UKB). From the first release of UKB whole-genome sequencing (WGS) data, a discovery analysis in White British individuals reveals that rDNA CN associates with altered counts of specific blood cell subtypes, such as neutrophils, and with the estimated glomerular filtration rate, a marker of kidney function. Similar trends are observed in other ancestries. A range of analyses argue against reverse causality or common confounder effects, and all core results replicate in the second UKB WGS release. Our work demonstrates that rDNA CN is a genetic influence on trait variance in humans.

Humans↗

PubMed1975

On the statistical significance of primary structural features found in DNA-protein interaction sites.

Probabilities of occurrence for a number of the symmetries and other sequence regularities found in DNA-protein interaction site sequences have been calculated for segments of random DNA sequence. Results show that many of the symmetrical and repetitive features seen in these interaction sites are likely to have occured by chance. Other features are so unlikely to have occurred by chance that they are probably involved in the DNA-protein interaction processes.

Amino Acid Sequence↗

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↗

PubMed2024

Advances in serum thyroid hormone levels and seizures.

Epilepsy, a common neurological disorder, is characterized by paroxysmal, short-term, repetitive, and stereotypical features, significantly impacting patients' quality of life. Currently, the pathogenesis of epilepsy remains incompletely understood. Changes in neuronal excitability, imbalances in glutamate and gamma-aminobutyric acid (GABA) levels, alterations in the activity of GABA receptors, and dysfunction of GABA receptors are considered closely related to its occurrence. Thyroid hormones, vital for human growth and development, also play a crucial role in the nervous system. They mediate oxidative stress, influence reactive oxygen species production, affect mitochondrial function and neuronal excitability, and modulate glutamate and GABA levels. Also, they combine with thyroid hormone receptors and exert genomic effects by regulating the expression of numerous genes. However, once there are defects in thyroid hormone signaling, these defects may lead to severe neurodevelopmental disorders that are associated with an increased frequency of seizures. The impact of antiseizure medications (ASMs) on serum thyroid hormone levels, particularly traditional ASMs, has been extensively studied. It is reported that conventional ASMs such as phenobarbital, phenytoin sodium, carbamazepine, and valproate sodium were more likely to induce subclinical hypothyroidism (elevated TSH with normal FT4) or isolated hypothyroidism (decreased FT4 with normal TSH). However, the new ASMs, such as levetiracetam, have no effect on thyroid hormone levels. Together, seizures not only affect thyroid hormone levels, but abnormal thyroid hormone levels can also influence seizures. However, the precise mechanism underlying the interaction between serum thyroid hormone levels and seizures remains unclear. This review aims to explore the relationship between thyroid hormone levels and seizures, along with the underlying mechanisms.

Humans↗

PubMed1976

The expression of normal ventricular repolarization in the body surface distribution of T potentials.

Isopotential maps from 120 normal subjects were obtained from 192 simultaneously recorded electrocardiographic leads. Maps were plotted at 1 msec intervals during the QRS and 5 msec intervals during the ST-T deflection. Repetition of QRS features was evident during all but the first few msec of the initial half of serial T maps. This suggests similarities of the normal sequence of ventricular excitation and recovery. Such similarities have been demonstrated by direct studies but are not evident from other electrocardiographic examinations. Serial maps during later portions of the T wave showed decreasing intensity of potentials with little change of body surface locations. This also correlates with an established feature of ventricular repolarization, namely that potential difference boundaries with stable locations are widely distributed during part of that process. Findings suggest isopotential maps show features of ventricular recovery not apparent from less extensive examinations.

Action Potentials↗

PubMed2026

The dark genome in cardiovascular medicine.

Only ∼1%-2% of the human genome directly codes for proteins. The remainder consists of non-coding DNA, often referred to as the 'dark genome'. This includes regulatory elements, transposable and repetitive sequences, structural genomic features, pseudogenes, intronic and intergenic regions, and non-coding RNA (ncRNA) genes. These components are increasingly recognized as major regulators of gene expression, cell identity, and disease susceptibility. Currently, dark genome elements, particularly ncRNAs are increasingly recognized as important regulators of cardiovascular health and disease. Advances in genome analysis technologies have greatly improved our understanding of these non-coding regions and revealed clearer connections between the dark genome and cardiovascular traits. This review highlights major parts of the dark genome involved in cardiovascular disease, with emphasis on those for which mechanistic understanding and translational relevance are beginning to emerge. As mechanistic insight into individual and collective components of the dark genome advances, it increasingly enables the development of new opportunities for targeted therapeutics for cardiovascular prevention and disease management.

Humans↗

PubMed1976

Lower extremity atheromatous embolization.

Eleven patients with lower extremity atheromatous microembolization are described. The diagnostic feature of sudden, often repetitive, episodes of focal ischemia, patent major arteries of the legs, and arteriographic demonstration of nonocclusive atheromas of the proximal arterial tree are characteristic. Successful removal of the causative lesion in these patients has prevented further ischemic episodes.

Adult↗

PubMed1977

Sickle cell trait and hematuria associated with von Willebrand syndromes.

A von Willebrand syndrome was present in four patients with sickle cell trait and hematuria. The first two patients had severe anemia and active bleeding and received cryoprecipitate, with prompt cessation of hemorrhage. All of the patients had repetitive laboratory and clinical features; that is, reduced, but detectable, factor VIII-related antigen, heterogeneity of, and incongruities within, the coagulation studies performed by consistently defective platelet aggregation to ristocetin correctable only with normal plasma. Bleeding outside the genitourinary tract never was observed. Because of the focal nature of the hemorrhage, the hematuria may not have been perceived as part of a general hemorrhagic disorder and the diagnosis not pursued. These observations suggest that when sickle cell trait and hematuria occur together, a von Willebrand syndrome should be a major diagnostic consideration that ultimately may point toward a rational, effective, easily administered, and clinicially acceptable form of treatment with cryoprecipitate.

Adolescent↗

PubMedDate not supplied

[Necrotizing herpetic encephalitis. Electro-clinical and pathological studies on two infantile cases (author's transl)].

The electroclinical and pathological features of two infantile cases of acute necrotizing herpetic encephalitis are reported. The distribution of the lesions has been compared with those observed in fourteen other cases including four with EEG records. Various electroencephalographic features have been recorded including repetitive slow spikes and periodic stereotyped paroxysmal discharges. The pathological data are interpreted to attempt unravelling the physiopathology of the EEG features.

Adult↗

PubMed1979

Translocation and other recombination events involving the tetracycline-resistance element Tn10.

Insertions of Tn10 are characterized by the presence of a direct repetition of a 9-bp target gene sequence on either side the insertion. The occurrence of these repetitions undoubtedly reflects an important feature of the way in which DNA molecules are broken and joined during translocation. Our experiments further suggest, however, that these 9-bp sequences are probably not responsible for Tn10-insertion specificity and that their presence is not required for normal Tn10 translocation elsewhere. We therefore suggest that the genetic information which controls the quality and quantity of Tn10 translocation actually resides somewhere other than these 9-bp sequences. We presume that much of this information lies within the ends of Tn10 itself and that signals on the target DNA which guide Tn10 to preferred positions must occur near, but not actually at, the eventual physical site of the integration event. Consideration of Tn10-promoted deletions and inversions reemphasizes the role of these ends in Tn10-promoted recombination events. Since Tn10-promoted events almost always consist in joining the physical end of one of the putative IS sequences of Tn10 to some other DNA segment, one comes again to the conclusion that these ends must contain important genetic information governing recombination events.

Bacteriophage lambda↗

PubMed1977

Response times to stimuli of increasing complexity as a function of ageing.

Twelve elderly and 12 young subjects were tested on a series of experiments with increasing complexity of perceptual-response mapping. As task complexity increased the differential slowing in performance between young and old increased and an ageXtask complexity interaction was observed. However, with practice this phenomenon disappeared leaving an apparent age lag constant. This slowing was due to increased central processing time rather than peripheral factors. No major differences in strategies were observed between the groups, though the old subjects tended to be less able to extract critical (useful) features from the display. Stimulus repetitions of a new kind were found where all characteristics of the stimulus (relevant and irrelevant) were important. Repetitions of coding rules rather than of particular signals or responses also facilitated RT. It was also found that later in practice old subjects were making fewer errors than the young, reversing earlier observations.

Adult↗

PubMed1979

Chronic repetitive supraventricular tachycardia in infancy and childhood.

Over a period of 7 years, 10 patients with chronic repetitive supraventricular tachycardia have been observed. The clinical features, therapeutic results and prognostic observations are reported. Since the cases of sustained type turn into repetitive type, it is emphasized that differentiation of the two forms is unnecessary.

Adolescent↗

PubMed1977

Structure of the inverted terminal repetition of adenovirus type 2 DNA.

Several secondary structure features involving the ends of single strands of adenovirus type 2 DNA have been studied by electron microscopy by both the gene 32-ethidium bromide technique and a modification of the standard formamide-cytochrome c technique. A duplex stem of length 115 +/- 10 nucleotide pairs due to pairing between the two members of the inverted terminal repetition is observed in the single-stranded circles that form upon annealing single-stranded linear molecules. This duplex stem is shown to lie at the ends of the DNA by using several reference markers: (i) a newly discovered secondary structure feature (a loop of length ca. 500 nucleotides with a 20-nucleotide pair duplex stem) that maps 73% of the full length from the left end of the molecule and (ii) a duplex region due to a hybridized restriction fragment. There is also some secondary structure within each end of linear single strands. There is some variation in the morphology of the end strucures, and we propose that these involve base pairing, as in a tRNA clover leaf, rather than an exact single hairpin-type inverted repeat. These observations are consistent with the hypothesis that there is a foldback structure at the 3' ends of the DNA that functions as a primer for the initiation of replication.

Adenoviruses, Human↗

PubMed2025

A complete and near-perfect rhesus macaque reference genome: lessons from subtelomeric repeats and sequencing bias.

A truly complete, telomere-to-telomere (T2T), and error-free reference genome remains a foundational resource-and long-standing goal-for unbiased comparative and functional genomics. While recent T2T assemblies of humans and other primates have made substantial progress, most still contain thousands of base-level errors, particularly within highly repetitive regions. Here, we present T2T-MMU8v2.0, a near-perfect T2T assembly of the rhesus macaque (Macaca mulatta), representing the highest base-level accuracy reported in a primate genome to date. By employing an optimized ONT-only assembly strategy, we identify subtelomeric satellite-rich regions as the principal bottleneck to improving assembly quality, owing to technological biases in long-read platforms and limitations in current hybrid assembly frameworks. We discover 268 previously unannotated repeat families and resolve ~8 Mbp of SATR satellite arrays, with over 99-fold enrichment in historically misassembled subtelomeric regions. These satellites form four distinct genomic architectures, each with unique SATR satellite composition, segmental duplication organization, and epigenetic signatures, distinct from the subtelomeric architectures observed in hominid genomes. Notably, in contrast to the largely gene-poor subtelomeric regions in African hominids, the SATR architectures in macaques harbor 58 actively transcribed genes, supported by open chromatin and expression data, suggesting gene innovation within these repetitive regions. Functionally, T2T-MMU8v2.0 improves read mappability and accuracy across sequencing platforms, and results in a 19% improvement of transcription start site enrichment scores and 5,821 additional chromatin accessibility peaks on average, thereby enhancing variant detection, regulatory annotation, and transcriptomic resolution in population genetics or single-nucleus studies. Together, this work establishes a new benchmark for genomics, offers a roadmap for resolving complex repetitive regions, and reveals previously unrecognized features of subtelomeric genome structure and evolution.

Journal Article↗

PubMedDate not supplied

Solitary reticulum cell sarcoma of the uterine cervix with initial cytodiagnosis.

A minimally symptomatic elderly woman was discovered to have reticulum cell sarcoma involving the uterine cervix on the basis of cervico-vaginal smears taken in the absence of a visible mass lesion. The diagnosis was confirmed by biopsy, and subsequent clinical and operative staging revealed the tumor to be arising in and confined to the uterine cervix. The cytologic features of reticulum cell neoplasia are repetitive and highly characteristic irrespective of its site of origin.

Aged↗

PubMed1976

Orofacial dyskinesia. Clinical features, mechanisms and drug therapy.

Orofacial or tardive dyskinesias are involuntary repetitive movements of the mouth and face. In most cases, they occur in older psychotic patients who are in institutions and in whom long-term treatment with antipsychotic drugs of the phenothiazine and butyrophenone groups is being carried out. These dyskinesias are frequent in occurrence and characteristically are irreversible. Several biochemical mechanisms have been proposed as causes, including hypersensitivity or partially deneverated brain dopamine receptors and low affinity of the offending drugs for brain muscarinic cholinergic receptors. Clinical therapy has been attempted primarily with drugs that antagonize dopamine receptors or deplete brain dopamine. The benefits of drug treatment have been variable and lack of consistent improvement has been discouraging. Early recognition of dyskinesia should be attempted, and the dose reduced or the drug omitted at the first sign.

Antipsychotic Agents↗

PubMedDate not supplied

Chromatin alterations and gene function disorder in MC-29 virus-derived hepatoma.

The disorder of gene expression in hepatomas was studied by following certain metabolic alterations (enzyme stimulation, nucleic acid labeling) after glucocorticoid treatment and analyzing the site of action of glucocorticoids. Compared to normal liver, the MC-29 virus-derived transplantable hepatoma (VTH) responded abnormally to glucocorticoids, which failed to stimulate the activity of certain enzymes (glucose-6-phosphatase, aryl hydrocarbon hydroxylase) or to inhibit DNA synthesis. Since the binding capacity of the cytosol steroid receptor was the same in liver and VTH but the interaction between the steroid receptor and DNA was reduced in VTH, it was concluded that structural alterations of chromatin nonhistones--including processed steroid receptor--may be responsible for the lack of physiological responses to steroids in VTH. Furthermore, the increased proportion or repetitive sequences in VTH DNA may be a feature of the disorder of gene regulation in malignant cells.

Animals↗

PubMed1978

A fully coupled transient excited state model for the sodium channel. II. Implications for action potential generation, threshold, repetitive firing, and accommodation.

The axon membrane is simulated by standard Hodgkin-Huxley leakage and potassium channels plus a coupled transient excited state kinetic scheme for the sodium channel. This scheme for the sodium channel is as proposed previously by the author. Simulations are presented showing the form of the action potential, threshold behavior, accommodation, and repetitive firing. It is seen that the form of the individual action potential, its all-or-none nature, and its refractory period are well simulated by this model, as they are by the standard Hodgkin-Huxley model. However, the model differs markedly from the Hodgkin-Huxley model with respect to repetitive firing and accommodation to stimulating currents of slowly rising intensity, in ways that are shown to be related to those features of the sodium inactivation which are anomalous to the H-H model. The tendency for repetitive firing is highly dependent on that parameter which primarily determines the existence of the inactivation shift in voltage clamp experiments, in such a way that the more pronounced the inactivation shift, the less the tendency for repetitive firing. The tendency for accommodation is highly dependent on that parameter which primarily determines the 'tauc-tauh' separation, in such a way that the greater the separation the greater the tendency for the membrane to accommodate without firing action potentials to a slowly rising current.

Action Potentials↗