Heart rate and oxygen consumption during active psychological challenge: the effects of level of difficulty.
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Adolescent↗
Biomedical subjects
D Carroll
Publications and source records attributed to D Carroll.
Tx1: a transposable element from Xenopus laevis with some unusual properties.
A family of transposable genetic elements in the genome of the frog, Xenopus laevis, is described. They are designated Tx1. Transposability of the elements was deduced by characterization of a chromosomal locus which is polymorphic for the presence or absence of a Tx1 element. Nucleotide sequence analysis suggested that Tx1 elements show target site specificity, as they are inserted at the pentanucleotide TTTAA in all four cases that were examined. The elements appear to have 19-base-pair (bp) inverted terminal repeats, and they are flanked by 4-bp target duplications (TTAA), although the possibility that they do not create target site duplications is discussed. Tx1 elements have several unusual characteristics: the central portion of each element is comprised of a variable number of two types of 393-bp repeating units; the rightmost 1,000 bp of the element contains separate regions potentially capable of forming bends, left-handed Z-form DNA, and alternative stem-loop structures. Comparisons among single frogs suggest that germ line transposition is relatively infrequent and that variations in numbers of internal repeats accumulate quite slowly at any locus.
Animals↗
Efficient homologous recombination of linear DNA substrates after injection into Xenopus laevis oocytes.
When DNA molecules are injected into Xenopus oocyte nuclei, they can recombine with each other. With bacteriophage lambda DNAs, it was shown that this recombination is stimulated greatly by introduction of double-strand breaks into the substrates and is dependent on homologous overlaps in the recombination interval. With plasmid DNAs it was shown that little or no recombination occurs between circular molecules but both intra- and intermolecular events take place very efficiently with linear molecules. As with the lambda substrates, homology was required to support recombination; no simple joining of ends was observed. Blockage of DNA ends with nonhomologous sequences interfered with recombination, indicating that ends are used directly to initiate homologous interactions. These observations are combined to evaluate possible models of recombination in the oocytes. Because each oocyte is capable of recombining nanogram quantities of linear DNA, this system offers exceptional opportunities for detailed molecular analysis of the recombination process in a higher organism.
Animals↗
Stress inoculation training to control anxiety in sport: two case studies in squash.
This study arose as a result of two squash players, one male one female, seeking advice on how to improve their mental approach to playing. They both felt that their game suffered badly through too much anxiety. After preliminary interviews it was decided to use a programme of stress inoculation training to help them learn to control their anxiety. In order to obtain baseline measures of anxiety, both subjects completed a state anxiety questionnaire on five occasions, immediately prior to playing important league or team matches. They were then given eight training sessions. On completion of the training, subjects were asked to complete a further five state anxiety tests immediately prior to analogous matches. There was a considerable decrease in self-reported anxiety levels and both players reported that their performance had improved. It is argued that stress inoculation training is potentially very useful as a technique for controlling anxiety in certain competitive sports.
Adaptation, Psychological↗
Stress inoculation training: a case study in gymnastics.
A young female gymnast of regional squad potential had ceased to make progress when she resumed training after a series of injuries and was given stress inoculation training to help her to regain her form. Preliminary interviews revealed that she had developed a number of negative self-statements and images which, it was hypothesised, may have been contributing towards her lack of progress. In order to replace these with positive self-statements and images a treatment programme of eight training sessions was implemented. Recorded interviews and subsequent comparison of comments made by the subject before and after the intervention programme, indicated that the training had been successful. This was endorsed by the coaches who reported an improved attitude to training and rapid progress in skill learning.
Child↗
A twin study of cardiac reactivity and its relationship to parental blood pressure.
The cardiac reactivity of 40 monozygotic and 40 dizygotic pairs of young male twins was monitored during psychological challenge, as afforded by a video game. The observed pattern of variation could not be accounted for solely by environmental factors. In fact, a simple genetic model that implicated additive genetic effects, along with those stemming from individual environments, best fitted the data. In addition, cardiac reactions were substantially greater for subjects whose parents both had relatively elevated blood pressure. Overall, these data suggest individual differences in cardiac reactivity have a heritable component, and that high reactivity may be a precursor of elevated blood pressure.
Adolescent↗
Zomepirac, dihydrocodeine and placebo compared in postoperative pain after day-case surgery. The relationship between the effects of single and multiple doses.
Zomepirac 100 mg and dihydrocodeine 30 mg were compared with placebo in a controlled randomized, double-blind, single-dose postoperative study. Patients continued to receive either zomepirac or dihydrocodeine for pain relief for 5 days at home in a double-blind study, being allowed to titrate the consumption of tablets to their degree of pain. The efficacy and side effects of the medication were evaluated. In the single-dose phase, both active treatments were significantly better than placebo. In the multiple dosing phase, zomepirac was statistically better than dihydrocodeine. Non-parametric statistical tests indicated highly significant correlations between single- and multiple-dose analgesic measurements for both zomepirac and dihydrocodeine.
Administration, Oral↗
Heart rate and oxygen consumption during mental arithmetic, a video game, and graded exercise: further evidence of metabolically-exaggerated cardiac adjustments?
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Adolescent↗
The effects of spinal injury on the intensity of emotional experience.
Twenty-nine subjects with spinal lesions were asked whether the intensity of their experience of eight common emotions had decreased, increased or stayed the same since injury. Analysis of their responses produced no evidence of a decline in affective tone following spinal injury.
Adult↗
Genetic recombination of Xenopus laevis 5 S DNA in bacteria.
The behavior in genetic recombination of Xenopus laevis 5 S DNA has been examined, with particular emphasis on the role of 15-base-pair tandem repeats in the A + T-rich spacer. Fragments of 5 S DNA were introduced into Escherichia coli cells as inserts in the recombination vectors, lambda rva and lambda rvb. Intermolecular recombinants were selected in which, because of properties of the phage vectors, the crossover event must have occurred within the 5 S DNA inserts. Inserts from individual recombinants have been characterized in detail. The effects of varying the number (n) of 15-base-pair repeats and the recombination capabilities of the phage and host have been investigated. In these crosses, unequal crossovers can occur, yielding inserts different in size from the parental inserts. When the number of 15-mers is large (n = 12 or 20), most of the unequal crossovers have occurred within the 15-mers, resulting in an altered n value, although other homologies within the 5 S DNA sequence can also support unequal events. Increasing n in the parental inserts modestly increases the overall frequency of recombination and the percentage of altered inserts. We conclude that, in a bacterial setting, the 15-base-pair repeats stimulate recombination only slightly by allowing alternative registers for heteroduplex formation. The degree of stimulation observed is less than predicted by one simple model.
Animals↗
The nucleotide sequence of the Escherichia coli K12 nusB (groNB) gene.
The nusB (groNB) gene product of Escherichia coli plays a pivotal role in allowing bacteriophage lambda N protein to function as an antiterminator of mRNA transcription and in modulating host gene expression. In addition it is essential for bacterial viability since mutations in it result in a cold-sensitivity phenotype for growth. We have previously cloned the nusB gene and shown it to code for a 14,500-Mr protein. Here we present the primary DNA sequence of the nusB gene. From the sequence we deduce that it codes for a slightly basic protein (21 basic as opposed to 20 acidic amino acids) composed of 139 amino acids with a cumulative 15,689-Mr. The predicted N-terminal amino acid sequence as well as the overall amino acid composition agrees well with that of the purified protein.
Amino Acid Sequence↗
Automated external defibrillation: laboratory evaluation.
Twelve samples of ventricular fibrillation were fed into nine automated external defibrillator-pacemakers ( AEDP , "Heart Aid") of recent design. All the devices recognised and defibrillated ventricular fibrillation in seven of the samples within 30 sec. None of the devices reacted to two of the samples; in the remaining three there was inter-device variation ranging from an appropriate response to no response, as well as inappropriate pacing or delay in recognition and treatment. Poor recognition of some ventricular fibrillation waveforms with considerable inter-device variation limits the usefulness of this model. A new prototype responded more consistently and future models may be of value in community resuscitation. The difficulty of evaluating the diagnostic capability of AEDP devices in clinical use makes comprehensive laboratory testing essential prior to release.
Electric Countershock↗
Temporal consistency of individual differences in cardiac response to a video game.
Three experiments are reported which examined the temporal stability of cardiac reactions to a video game of the 'space invaders' genre. Experiment 1 also addressed the matter of inter-task consistency; in addition to the video game, subjects were presented with an unsignalled reaction time task and led to believe that relatively quick reactions attracted financial reward, while slower ones brought either a burst of loud noise or withdrawal of money previously earned. Forty-two male subjects were tested on both tasks on two occasions, a week apart. Of the two tasks, the video game elicited the greater reactivity. In addition, individual variations in reactivity showed striking temporal stability for both tasks. However, inter-task consistency was much less marked; in fact, a significant inter-task correlation was obtained only on the first occasion of testing. It is probable that limited consistency here was in some measure due to the ineffectiveness of our reaction time task in eliciting substantial reactivity. Finally, reactivity was independent of baseline heart rate level. In experiment 2, three extreme high and three extreme low cardiac reactors were selected from an initial sample of 23 male subjects, on the basis of reactivity during an initial session with the video game, and subsequently studied during four further sessions. Once more, impressive stability of heart rate reactivity was apparent over sessions. In experiment 3, we examined the reliability of individual variations in cardiac reactivity in women and the issue of whether temporal stability is constrained by menstrual cycle effects. Twenty-four females were tested on the video game both preovulatory and postovulatory, with half being tested first during the preovulatory phase and half being tested first during the postovulatory phase. Again, the most striking finding was the marked stability of individual variations in cardiac reactivity over both time and menstrual cycle phase.
Adolescent↗
Control of oxygen delivery from the erythrocyte by modification of pyruvate kinase.
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Cyclic AMP↗
Isolated clusters of paired tandemly repeated sequences in the Xenopus laevis genome.
There exist in the Xenopus laevis genome clusters of tandemly repeated DNA sequences, consisting of two types of 393-base-pair repeating unit. Each such cluster contains several units of one of these paired tandem repeats (PTR-1), followed by several units of the other repeat (PTR-2). The number of repeats of each type is variable from cluster to cluster and averages about seven of each type per cluster. Every cluster has ca. 1,000 base pairs of common left flanking sequence (adjacent to the PTR-1 repeats) and 1,000 base pairs of common right flanking sequence (adjacent to the PTR-2 repeats). Beyond these common flanks, the DNA sequences are different in the eight cloned genomic fragments we have studied. Thus, the hundreds of PTR clusters in the genome are dispersed at apparently unrelated sites. Nucleotide sequences of representative PTR-1 and PTR-2 repeats are 64% homologous. These sequences do not reveal an obvious function. However, the related species X. mulleri and X. borealis have sequences homologous to PTR-1 and PTR-2, which show the same repeat lengths and genomic organization. This evolutionary conservation suggests positive selection for the clusters. Maintenance of these sequences at dispersed sites imposes constraints on possible mechanisms of concerted evolution.
Animals↗
Evidence for cardiovascular autonomic nerve dysfunction in multiple sclerosis.
In 21 patients with multiple sclerosis and 20 healthy controls, the following tests of autonomic function were examined: (1) variation in heart rate during deep breathing, (2) the variations in heart rate and systolic blood pressure during a standardised Valsalva manoeuvre, (3) the changes in heart rate and systolic blood pressure during arm ergometry starting at 30 W with increments of 20 W every 3 min. In the control subjects the maximum variation in heart rate from inspiration to expiration was greater than 16 beat/min (range 17-43). In patients with multiple sclerosis, five had a maximum variation in heart rate of less than 13 beat/min which was considered as the lower limit of normal. The Valsalva ratio in the control subjects ranged from 1.33-3.24. Four patients had Valsalva ratios of less than 1.30. In patients with multiple sclerosis the heart rate and systolic blood pressure responses to exercise were attenuated significantly in four and seven subjects respectively. It is concluded that a significant number of patients with multiple sclerosis show evidence of autonomic dysfunction involving the cardiovascular system.
Adult↗
Regulating, psychosurgery: ethical, social and scientific considerations.
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Behavior Control↗
Tandemly repeated DNA sequences from Xenopus laevis. I. Studies on sequence organization and variation in satellite 1 DNA (741 base-pair repeat).
A family of tandemly repeated sequences, having a basic repeating unit of 741 base-pairs, has been identified in Xenopus laevis DNA and designated satellite 1. Apart from its rather long repeat unit, the characteristics of this DNA appear to be quite similar to those of complex satellite DNAs from other organisms. The nucleotide sequence of a cloned repeat unit shows no evidence of simpler internal repeats, and there is no obvious suggestion of reasonable RNA- or protein-coding regions. Transcripts homologous to this DNA could not be demonstrated in liver, embryo or oocyte RNAs. By blot-hybridization, satellite 1 has been shown to exist in the genome chiefly as tandem repeats of the 741 base-pair sequence. However, there are a number of repeats that differ from the normal sequence (as judged by loss or gain of restriction sites) and some that differ in length. Similar variants are often, but not always, clustered. Characterization of genomic clones of this satellite has confirmed the tandem organization and clustering of variants. The nature of some variants has been elucidated in more detail. Some regions of the basic repeat seem to be more prone to variation than are others.
Animals↗