SEARCH · Search PubMed

Results for “repeat interruptions”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

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

At least 793 records · Page 44Linked to original sources

PubMed1983

Transcription analyses with heteroduplex trp attenuator templates indicate that the transcript stem and loop structure serves as the termination signal.

DNA sequences that control transcriptional termination by prokaryotic RNA polymerases normally contain an inverted repeat, or self-complementary sequence, about 10 base pairs upstream from the site of RNA chain termination. Point mutations that interrupt this self-complementarity can reduce or eliminate RNA chain termination. We have constructed heteroduplex DNA templates using wild type and mutant attenuators for the Escherichia coli trp operon to probe the relative contributions of the two DNA strands in the termination process. Transcription analyses show that only the sequences in the transcribed DNA strand determine whether or not a heteroduplex terminator can function. This result strongly supports a model in which the formation of a stem and loop structure in the nascent RNA transcript is the signal for transcriptional termination.

DNA, Bacterial↗

PubMed1980

[Prenatal diagnosis of upper limb malformations].

Three children with thrombopenia and radial aplasia were examined at the Centre de Génétique Médicale of Marsielles from 1974 to 1976. In each case the genetic basis of the anomaly was discussed with the family at genetic counseling underlining the high risk of recurrence related to the autosomal recessive transmission. Each proband was the only child of the couple. In the first case the father and mother, each having one child from a previous marriage, decided to have no more children. In the second case, the use of fetoscopy and its limitations were discussed as another pregnancy was desired. However, the parents finally refused the procedure during pregnancy which yielded a second child with phocomelia who did not survive. In the third and most recent case the proband died. Since the young couple strongly desired another child, ultrasonic monitoring of pregnancy was cautiously suggested and its limitations clearly exposed. Echography was regularly repeated from the third month of pregnancy. The forearms were never detected on echography, nor on fetal radiography. Pregnancy was thus interrupted with prostaglandins at 21 weeks gestational age. On examination the fetus presented bilateral aplasia of the forearm. Based on these observations, the authors discuss the problems raised by prenatal diagnosis of upper limb malformations.

Ectromelia↗

PubMed1993

The processing of macronuclear DNA sequences during macronuclear development of the hypotrichous ciliate Stylonychia lemnae.

The organization of two macronuclear DNA sequences in the polytene chromosomes of the hypotrichous ciliate Stylonychia lemnae and their processing from the micronucleus via the polytene chromosome stage up to the macronucleus was analyzed. The overall organization of these sequences in the polytene chromosomes resembles that described for the micronucleus of other hypotrichous ciliates, i.e. they are interrupted by internal eliminated sequences and not associated with telomeric sequences. The spacer region between the genes is bordered by direct repeats and inverted repeats are found at the termini of macronuclear sequences and in the spacer region. The organization of these macronuclear DNA sequences in the micronucleus was analyzed by polymerase chain reactions. The results obtained show that in the sequences analyzed no DNA reorganization occurs during polytene chromosome formation.

Animals↗

PubMed1998

Nested insertions of short mobile sequences in Drosophila P elements.

A potentially full-sized P element isolated from the genome of Drosophila ambigua by polymerase chain reaction amplification was completely sequenced. It has a length of 3329 bp and the termini are formed by 33 bp inverted repeats. Sequence comparisons show that it can be classified as a member of the T-type P element subfamily. The translational reading frames of all four exons are interrupted by stop codons and frameshift mutations. At the 3' end of exon 3 a 687 bp insertion sequence (IS-amb-P) is found that also occurs in the form of dispersed copies (IS-amb) in the genome in D. ambigua. At the interspecific level it shows homology to mobile sequences of other species of the obscura group. Although variable in length, these IS elements are characterized by conserved sections without coding function and by 14 bp inverted repeats, one at a terminal, the other at a subterminal position. In situ hybridization revealed that P elements in D. ambigua are restricted to only two euchromatic sites on chromosome elements A and E. This situation resembles that found in Drosophila guanche and Drosophila subobscura where P homologs are clustered at a single site on chromosome element E and where the section corresponding to exon 3 of P elements carries an IS element. The gene sik-hom, which is located at the 5' side of the D. guanche cluster of P homologs, was used as a marker to examine whether the P element sites on chromosome element E of D. guanche and D. ambigua are homologous. The results suggest that the nested insertions of IS elements into P elements must have occurred independently in the two different lineages.

Amino Acid Sequence↗

PubMed2002

Adverse outcomes of interrupted precordial compression during automated defibrillation.

BACKGROUND: Current versions of automated external defibrillators (AEDs) require frequent stopping of chest compression for rhythm analyses and capacity charging. The present study was undertaken to evaluate the effects of these interruptions during the operation of AEDs. METHODS AND RESULTS: Ventricular fibrillation was electrically induced in 20 male domestic swine weighing between 37.5 and 43 kg that were untreated for 7 minutes before CPR was started. Defibrillation was attempted with up to 3 sequential 150-J biphasic shocks, but each was preceded by 3-, 10-, 15-, or 20-second interruptions of chest compression. The interruptions corresponded to those that were mandated by commercially marketed AEDs for rhythm analyses and capacitor charge. The sequence of up to 3 electrical shocks and delays were repeated at 1-minute intervals until the animals were successfully resuscitated or for a total of 15 minutes. Spontaneous circulation was restored in each of 5 animals in which precordial compression was delayed for 3 seconds before the delivery of the first and subsequent shocks but in none of the animals in which the delay was >15 seconds before the delivery of the first and subsequent shocks. Longer intervals of CPR interventions were required, and there was correspondingly greater failure of resuscitation in close relationship to increasing delays. The durations of interruptions were inversely related to the durations of subthreshold levels of coronary perfusion pressure. Postresuscitation arterial pressure and left ventricular ejection fraction were more severely impaired with increasing delays. CONCLUSIONS: Interruptions of precordial compression for rhythm analyses that exceed 15 seconds before each shock compromise the outcome of CPR and increase the severity of postresuscitation myocardial dysfunction.

Animals↗

PubMed2002

Genomic analysis of the terpenoid synthase ( AtTPS) gene family of Arabidopsis thaliana.

A family of 40 terpenoid synthase genes ( AtTPS) was discovered by genome sequence analysis in Arabidopsis thaliana. This is the largest and most diverse group of TPS genes currently known for any species. AtTPS genes cluster into five phylogenetic subfamilies of the plant TPS superfamily. Surprisingly, thirty AtTPS closely resemble, in all aspects of gene architecture, sequence relatedness and phylogenetic placement, the genes for plant monoterpene synthases, sesquiterpene synthases or diterpene synthases of secondary metabolism. Rapid evolution of these AtTPS resulted from repeated gene duplication and sequence divergence with minor changes in gene architecture. In contrast, only two AtTPS genes have known functions in basic (primary) metabolism, namely gibberellin biosynthesis. This striking difference in rates of gene diversification in primary and secondary metabolism is relevant for an understanding of the evolution of terpenoid natural product diversity. Eight AtTPS genes are interrupted and are likely to be inactive pseudogenes. The localization of AtTPS genes on all five chromosomes reflects the dynamics of the Arabidopsis genome; however, several AtTPS genes are clustered and organized in tandem repeats. Furthermore, some AtTPS genes are localized with prenyltransferase genes ( AtGGPPS, geranylgeranyl diphosphate synthase) in contiguous genomic clusters encoding consecutive steps in terpenoid biosynthesis. The clustered organization may have implications for TPS gene evolution and the evolution of pathway segments for the synthesis of terpenoid natural products. Phylogenetic analyses highlight events in the divergence of the TPS paralogs and suggest orthologous genes and a model for the evolution of the TPS gene family.

Alkyl and Aryl Transferases↗

PubMed1995

Interrupted arterial occlusion reduces ischemic damage in a focal cerebral ischemia model of rats.

It is generally thought by neurosurgeons that when temporary clipping of a major cerebral vessel is necessary during aneurysm surgery, repeated short periods of cerebral ischemia are safer for the brain than a single long episode. This study was performed to investigate whether repetitive short episodes of cerebral ischemia would alter the resulting brain injury as compared with a single long period of ischemia in a rat model for focal cerebral ischemia. Middle cerebral artery occlusion and reperfusion were performed by the intraluminal thread technique. The experimental design consisted of a single 90-minute occlusion period in the continuous ischemia group versus three 30-minute occlusion periods with 15-minute reperfusion periods in the repetitive group. Local cerebral blood flow was measured by the hydrogen clearance technique. During the ischemic period, local cerebral blood flow values significantly decreased in both the continuous and the repetitive groups. Cerebral blood flow restoration was demonstrated after each episode of reperfusion in both groups. The neurological status scores 2 hours after surgery in the rats subjected to repetitive insults were significantly better compared with those in the rats of the continuous ischemia group. However, the scores on Days 1, 3, and 7 did not show a significantly better difference. The animals were killed 7 days after the induction of ischemia for the measurement of the infarction area under the microscope. The total area of infarction was significantly reduced (4.05 +/- 4.56 versus 47.2 +/- 37.3 mm2, P < 0.001) by interruption of the ischemic time period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

Identification of three novel mutations in the KAL1 gene in patients with Kallmann syndrome.

Kallmann's syndrome (KS) is characterized by the association of hypogonadotropic hypogonadism and anosmia or hyposmia. Genetic defects have been observed throughout the KAL1 gene, located on the Xp22.3 region, in less than 50% of the patients. We report the molecular study of the KAL1 gene in 12 males with KS. PCR of the 14 exons of the KAL1 gene was performed on genomic DNA. PCR products of all exons were purified and sequenced. Three novel genetic defects were found. One patient exhibited a complete deletion of exon 5. The second presented a duplication of nucleotides 158-168; this insertion causes a termination codon (TGA) within the same exon. The third presented a mutation in exon 6, in which codon 262 changes from arginine to a stop codon. In the remaining nine individuals, no mutations were found. Three previously reported polymorphic changes were also documented. The deletion of exon 5 occurs within the region encoding the first fibronectin type III-like repeat of the KAL1 protein, this being the first KS patient who exhibits a complete deletion of a single exon of the KAL1 gene. The duplication of nucleotides in exon 1 is located in the conserved cysteine-rich N-terminal region that corresponds to the whey acidic protein motif, affecting the KAL1 protein either by interrupting the normal transcription or stopping the translation at the stop codon. The last novel mutation, a stop codon in exon 6, is located within the region encoding the first fibronectin type III-like repeat of the KAL1 protein. The absence of mutations in the majority of patients suggests the possibility of the existence of other genes involved or that in certain individuals the presence of various polymorphisms within the KAL1 gene could predispose to disease, as has been demonstrated in other pathological entities.

Adolescent↗

PubMed1994

Nucleotide sequence of the telomeric region of the African swine fever virus genome.

The 4-kb terminal BclI fragment of African swine fever virus (ASFV) DNA, including the inverted terminal repetition (ITR), was cloned and sequenced. The sequence showed that the 2.1-kb ITR is composed of a 301-nucleotide-long unique sequence immediately adjacent to the terminal hairpin loop, a set of 38 tandem direct repeats of a 34-nucleotide degenerate sequence, another unique intervening sequence with no remarkable features, and a set of 5 tandem repeats of a 27-nucleotide unit unrelated in sequence to the 34-nucleotide repeat unit. Several short repeats were found scattered along the most distal unique sequence. The proximal half of the terminal fragment possesses one complete and one interrupted copy of genes belonging to multigene family 360.

African Swine Fever Virus↗

PubMedDate not supplied

Collagen formation during the healing of colonic anastomoses.

To study new collagen formation in the healing of anastomoses in the right colon, five male Sprague-Dawley rats had single-layer colonic anastomosis performed. Five additional rats had suture of the colon with interrupted sutures without transection of the colon. Ten animals served as controls. One week after surgery, animals were given 3H-proline repeatedly to label new collagen formation during the second and third weeks. Animals were sacrificed three weeks after suturing or anastomosis. Two- or 10-mm segments were precisely excised on either side of the suturing or anastomoses. Total collagen and its total radioactivity were measured per segment. Collagen hydroxyproline and its radioactivity increased (100 per cent) only within 1 cm of the anastomosis or suture alone. No local or distant decrease in collagen was observed. Collagen formation in colonic wounds appears to be a local process.

Animals↗

PubMed1982

Adrenomedullary ornithine decarboxylase activity: its use in biochemical mapping of the origins of the splanchnic nerve in the rat.

The activity of ornithine decarboxylase in the adrenal medulla of the rat can be induced transsynaptically by the repeated administration of apomorphine. Unilateral section of one to four ventral spinal cord roots from T4 to T12 partially prevents this effects. Interruption of the intercostal nerves (T7--T13), with preservation of the autonomic innervation of the adrenal medulla, does not produce any alteration in the response of the medullary ODC to APO in the operated side as compared to the intact side. Dorsal root section at T7--T10 leads to a small reduction, while section at T2--T4 has no effect at all. Thus, selective surgical interruption of spinal cord roots indicates that the bulk of splanchnic fibers mediating the transsynaptic induction of adrenomedullary ornithine decarboxylase course in the ventral roots between T7 and T10. Dorsal rhizotomy demonstrates a modulatory role in this induction of afferent information to sympathoadrenal preganglionic neurons involved in innervation of the chromaffin cells.

Adrenal Medulla↗

PubMed2005

Flap suturing with proparacaine for recurrent epithelial ingrowth following laser in situ keratomileusis surgery.

PURPOSE: To evaluate the safety and efficacy of flap suturing with proparacaine application for the management of recurrent epithelial ingrowth following laser in situ keratomileusis (LASIK). SETTING: Private consultation practice and Department of Ophthalmology, Rush University, Chicago, Illinois, USA. METHODS: Six eyes of 5 patients with recurrent epithelial ingrowth had flap lifting followed by debridement of interface epithelial cells, interface application of proparacaine, and the placement of interrupted 10-0 nylon sutures. RESULTS: Four eyes achieved a best corrected visual acuity (BCVA) of 20/40 or better. Two eyes required repeat debridement with suturing and were stable with at least a 1-year follow-up. No eye lost more than 1 line of BCVA. Three eyes regained excellent uncorrected visual acuity due to a reduction in induced astigmatism. CONCLUSIONS: Recurrent epithelial ingrowth following LASIK surgery can be a visually debilitating condition. Flap suturing with interface proparacaine application may be effective in preventing further recurrences of epithelial ingrowth after initial debridement.

Adult↗

PubMed2006

Relation of dreams to waking concerns.

To test that dreams are influenced by the pre-sleep waking emotional concerns of the sleeper and have an effect on waking adaptation, 20 depressed and 10 control subjects, who were all going through a divorce, were enrolled in a repeated measures study lasting 5 months. A Current Concerns test was administered on three occasions before nights when every REM period was interrupted to record recalled mental content. The degree of waking concern about the ex-spouse correlated significantly with the number of dreams in which the former partner appeared as a dream character. Those who were in remission at the follow-up evaluation had a higher percentage of well-developed dreams than those who remained depressed. Dreams of the former spouse reported by those in remission differed from those who remained depressed in the expression of dream affect and in the within-dream linkage among units of associated memory material. Dreams of the former spouse that are reported by those who are not in remission lack affect and connection to other memories.

Adult↗

PubMed1984

[Withdrawal syndrome during epidural administration of morphine after stopping treatment with clonidine].

A 70 year old hypertensive patient who had undergone a gastrectomy experienced withdrawal symptoms 10 h after a second epidural injection of morphine (150 micrograms X kg-1) for postoperative analgesia. A clonidine treatment had been stopped 129 h earlier. These symptoms disappeared shortly after a third epidural injection of morphine. Clonidine was then reintroduced. The later progressive interruption of epidural morphine analgesia did not introduce any further symptoms of withdrawal. Since physical dependence on a drug is related to repeated and prolonged administration of that drug, opiate withdrawal symptoms were highly unlikely after epidural morphine used to relieve immediate postoperative pain. Abrupt discontinuation of a long-term treatment by clonidine may produce a withdrawal syndrome, but clinical and biological signs usually occur earlier than noted in this case. Recent experimental and clinical data has provided support for the existence of a complex presynaptic regulation of noradrenergic transmission in the central nervous system, both alpha 2 and opiate receptors being implicated. The activation of such presynaptic receptors inhibits further transmitter release. Suddenly stopping the chronic administration of alpha 2 or opiate agonists was responsible for a rebound excitation of these noradrenergic neurons, inducing a withdrawal syndrome. The related withdrawal symptoms may have resulted from an interaction between the discontinuation of clonidine and the decrease in morphine activity. Practitioners should be warned of this possible side-effects.

Aged↗

PubMed2001

Adjunctive gabapentin in patients with intellectual disability and bipolar spectrum disorders.

The aim of the present study was to assess the efficacy of adjunctive gabapentin (GBP) in the treatment of patients with intellectual disability (ID) and bipolar spectrum disorders. Ten affected subjects with demonstrable increases in symptomatology during 'significant' life events which had interfered with or induced the interruption of their rehabilitation programmes were chosen for this study. The meaning of 'significant' was defined for each patient as a frequently repeated life event which had elicited a marked increase in symptoms on at least two occasions. Gabapentin (300-900 mg day-1) was added to the standard therapy. The subjects' psychopathological conditions during the significant life event were assessed by means of standardized tools both before and after adjunctive therapy with GBP. A positive response to therapy was observed, with subsequent improvement of psychopathological conditions, particularly for anxiety and depressive symptoms. The promising results obtained with GBP suggest the need for further trials. Adjunctive GBP may become an alternative treatment approach for patients with ID in whom traditional mood-stabilizing agents have frequent contraindications.

Acetates↗

PubMed1956

The sarcoplasmic reticulum in muscle cells of Amblystoma larvae.

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.

Ambystoma↗

PubMed1984

Release and recycling of calcium by the sarcoplasmic reticulum in guinea-pig portal vein smooth muscle.

The amplitude of interrupted contractions evoked by noradrenaline or caffeine in Ca2+-free, high-K+ solutions containing EGTA or La3+ was determined in small (40-60 micron thick) bundles of guinea-pig portal anterior mesenteric vein. Interrupted contractions were produced by removing the stimulating agent as soon as the amplitude of the tension record reached its peak. The distribution of intracellular Ca2+ was determined, with electron probe X-ray microanalysis, in cryosections of preparations frozen in the relaxed state and at the peak of noradrenaline-induced contractions. Interrupted contractions of maximal or near-maximal amplitudes could be evoked every 2 min for up to 15 min in the virtual absence of extracellular Ca2+. If noradrenaline was allowed to remain in the solution throughout the period of spontaneous relaxation, a subsequent contraction could no longer be evoked in the absence of extracellular Ca2+. Interrupted contractions, similar to those evoked by noradrenaline, could also be stimulated by caffeine. The amplitude of reproducible interrupted contractions in Ca2+-free, high-K+ solution was graded with noradrenaline concentration. The ability of these smooth muscles to contract repeatedly and maximally in Ca2+-free solutions indicates the recycling of Ca2+ released from an intracellular store. The occurrence of these contractions in high-K+ (depolarizing) solutions supports the conclusion (Devine, Somlyo & Somlyo, 1972) that the release of intracellular Ca2+ is one of the mechanisms of pharmacomechanical coupling. The number of subplasmalemmal regions in which high Ca concentrations (greater than 10 mmol/kg dry wt.) were detected, with approximately 75 nm diameter electron probes, was reduced in muscles frozen at the peak of contraction, from 4.7/cell periphery in the relaxed to 1.4/cell periphery in the contracted preparations. In freeze-substituted smooth muscles, in which the membranes of the junctional sarcoplasmic reticulum could be visualized, the regions containing high Ca were identified as part of the sarcoplasmic reticulum (s.r.), indicating that the s.r. is the store from which noradrenaline and caffeine release Ca2+.

Animals↗

PubMed1998

Arousal shifts in quiescent locusts

Locusts are usually quiescent at night, but this state can be interrupted by spontaneous periods of motor activity, or arousals, that can also be induced by exposure to light stimuli. To investigate whether repeated arousing stimulation has any lasting effect on behaviour, locusts were confronted at night with a series of 1 s light stimuli. Groups of three stimuli at intervals of 60 s were repeated 11 times at 10 min intervals during the first experimental night, and three stimuli at intervals of 90 s were repeated at 15 min intervals during the next night. Arousals and the effects of stimulation were monitored as changes in the spike activity of muscles in the basal part (the scapus) of the right antenna. In the early part of the night preceding the presentation of the light stimuli, neither 60 s nor 90 s periods were present as significant peaks in spontaneous changes in spike activity. The initial stimulus of a series evoked an arousal response that habituated on repetition of the stimulus. The end of the series of stimuli was followed by changes in spike activity that tended to have the same periodicity as the preceding stimuli. Furthermore, a single light stimulus at the end of the night evoked changes in spike activity that again tended to have the same periodicity as the preceding entraining stimuli. Repeated stimulation may therefore establish a memory trace for the period of stimulation that can be recalled either spontaneously or by the application of an appropriate external stimulus.

Journal Article↗