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Biomedical subjects

E O'Brien

Publications and source records attributed to E O'Brien.

At least 37 records · Page 2Linked to original sources
PubMed1995

Diurnal blood pressure profile in older patients with isolated systolic hypertension. The SYST-EUR Investigators.

This study describes the diurnal blood pressure (BP) profile and identifies its correlates in older patients with isolated systolic hypertension (ISH). The ambulatory BP readings of 408 patients, aged > or = 60 years, with ISH on clinic measurement, enrolled in the placebo run-in phase of the Syst-Eur Trial were examined. The time-weighted 24 h BP, daytime and night-time BP and the cusum-derived crest and trough BP were computed to express the BP level. The daily alteration between the high and low BP span was estimated from the day-night BP difference, the cusum derived circadian alteration magnitude and plot height, as well as the amplitude of the Fourier curve. The 24 h SBP and DBP tended to be higher in men (150 +/- 15/82 +/- 9 mm Hg) than in women (147 +/- 17/79 +/- 10 mm Hg), but the sex difference was only significant for DBP. In multiple regression analysis, the 24 h SBP increased (P < 0.05) by 3 mm Hg for each 10 year increment in age and was also 10 mm Hg higher (P < 0.001) in smokers than in non-smokers; the 24 h DBP was 2 mm Hg higher (P < 0.05) in men than in women and decreased (P < 0.05) by 1.5 mm Hg for each 10 year increment in age. The day-night difference in SBP increased with 2 mm Hg for each 10 mm Hg increase in the conventional pressure, decreased with 5 mm Hg for each 10 year increment in age and was 6 mm Hg higher in smokers than in non-smokers; the day-night difference in diastolic pressure was 2 mm Hg greater in women than in men. We conclude that the main determinants of the diurnal BP variation in older patients with isolated systolic hypertension were sex, age, smoking habits and the level of pressure on conventional measurement.

Age Distribution↗
PubMed1995

Will mercury manometers soon be obsolete?

After a century of clinical use, the mercury sphygmomanometric technique of blood pressure (BP) measurement is under threat. There are three reasons for this: mercury is likely to be banned from hospital use because of the danger of toxicity, accurate automated devices are now available to replace the mercury sphygmomanometer and with the advent of 24 h ambulatory BP measurement into clinical practice, more reliance is being placed on BP behaviour rather than on casual measurements. The passing of the mercury sphygmomanometer from clinical practice raises two issues that merit deliberation. Without the mercury standard with which to compare measurements generated by algorithmic interpretation of BP, the clinician is dependent on the consistency and accuracy of such algorithms. If the millimetre of mercury is no longer the unit of measurement for BP, it will soon be replaced by the kilopascal thereby introducing, at least temporarily, the potential for uncertainty in clinical judgment.

Blood Pressure↗
PubMed1994

Game, set and MRCP.

Explore the source record for details and available documents.

Clinical Competence↗
PubMed1994

Cloning of the glucose 6-phosphate dehydrogenase gene from Plasmodium falciparum.

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is one of the human genetic traits that confer relative resistance against malaria caused by Plasmodium falciparum. It has been previously shown that this organism, during its intraerythrocytic development, produces its own G6PD, which has properties different from those of human G6PD. In order to investigate the role of this enzyme in parasite-host cell interactions, we have isolated the G6PD gene from Plasmodium falciparum as a set of overlapping lambda gt11 clones. By sequence analysis we have found a single open reading frame, uninterrupted by introns, coding for a protein of 910 amino acids, almost twice as long as any previously sequenced G6PD molecule. The P. falciparum G6PD mRNA is 5.1 kb in size and has an exceptionally long 5' untranslated region of some 1000 nucleotides. We have mapped the G6PD gene to chromosome 14. The C-terminal portion of the predicted protein, from amino acid 310-910 (except for an 'insert' of 62 amino acids), has 39% homology to human G6PD, with a number of characteristic, fully conserved peptides. The N-terminal portion of the predicted protein has no homology to G6PD, but it contains a peptide in which 7 out of 12 amino acids are identical to the putative glutathione binding site of human glutathione S-transferase.

Amino Acid Sequence↗
PubMed1994

Using Hawksley random zero sphygmomanometer as a gold standard may result in misleading conclusions.

We combined a database of paired blood pressure measurements taken using the Hawksley random-zero sphygmonanometer and a standard mercury sphygmomanometer and a database of paired measurements made on a SpaceLabs 90202 ambulatory blood pressure recorder and standard sphygmomanometer to determine how the SpaceLabs 90202 would have fared if it had been assessed against the Hawksley random-zero sphygmomanometer instead of a standard sphygmomanometer. The pooled database contained 255 triplicate readings. Using the standard sphygmomanometer as gold standard, the Spacelabs had a median error of 2 mm/Hg for both systolic and diastolic. Against the Hawksley random-zero sphygmomanometer, median error was -3 mm systolic and -6 mm diastolic. The proportion of errors > 10 mm rose from 11% (systolic) and 9% (diastolic) with the standard sphygmomanometer to 16% and 29% with the Hawksley random-zero sphygmomanometer. Because it underestimates systolic and diastolic pressures, the use of the Hawksley random-zero sphygmomanometer as a gold standard may have resulted in misleading conclusions about performance of some automated BP recorders.

Adult↗
PubMed1994

A comparison of the British Hypertension Society and Association for the Advancement of Medical Instrumentation protocols for validating blood pressure measuring devices: can the two be reconciled?

BACKGROUND: Experience with the original protocols of the Association for the Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society (BHS) for validating blood pressure has provided valuable insight into the methodological problems associated with device validation and has influenced both the BHS and the AAMI in revising their protocols. OBJECTIVES: To review the revisions of the original BHS and AAMI protocols; to compare the protocols; and, using the BHS protocol as a framework for validation, to determine how it should be modified to a protocol that will fulfil the criteria of both the AAMI and the BHS. CONCLUSIONS: The revised protocols have many similarities but there are some important differences. These differences merit consideration so as to facilitate manufacturers seeking to validate devices for acceptance in both Europe and the United States. Of the two protocols, the BHS protocol is the more elaborate in that (1) it takes particular care to ensure that observers are trained to a very high standard, (2) it makes provision for special group validation and (3) it recommends in-use validation of all devices. By modifying the BHS protocol, it is possible to validate blood pressure measuring devices (ambulatory devices require special consideration) to satisfy the criteria of both protocols.

Blood Pressure Determination↗
PubMed1994

Supporting parental bonding in the NICU: a care plan for nurses.

New and improved technology in the NICU has assisted in supporting critically ill neonates, especially those born at very low birth weights. These small patients require the dedicated hand of the NICU staff, but also the love and support of their parents. Family bonding in the NICU is often a very difficult process, which is interrupted by separation of parent and child at birth and continued by the physical constraints of this highly complex critical care environment. Neonatal nurses are most often the front line managers and coordinators of family care in the NICU. They are charged with the challenge of understanding and providing "state of the art" technological care in an environment that must also adapt to the ever changing needs of parents and families who cannot be considered visitors, but an integral part of their infants' care and survival. Each infant and family in the NICU requires individualized assessment and nursing care. This article reviews the process of parental bonding as it relates to the premature or ill infant and provides for nurses a plan of care written to foster and support family bonding in the NICU. Stages of bonding with a sick or premature infant are explored in the context of a theoretical framework of adaptation provided by Sister Callista Roy.

Humans↗
PubMed1994

Linkage disequilibrium patterns vary with chromosomal location: a case study from the von Willebrand factor region.

Linkage disequilibrium analysis has been used as a tool for analyzing marker order and locating disease genes. Under appropriate circumstances, disequilibrium patterns reflect recombination events that have occurred throughout a population's history. As a result, disequilibrium mapping may be useful in genomic regions of < 1 cM where the number of informative meioses needed to detect recombinant individuals within pedigrees is exceptionally high. Its utility for refining target areas for candidate disease genes before initiating chromosomal walks and cloning experiments will be enhanced as the relationship between linkage disequilibrium and physical distance is better understood. To address this issue, we have characterized linkage disequilibrium in a 144-kb region of the von Willebrand factor gene on chromosome 12. Sixty CEPH and 12 von Willebrand disease families were genotyped for five PCR-based markers, which include two microsatellite repeats and three single-base-pair substitutions. Linkage disequilibrium and physical distance between polymorphisms are highly correlated (rm = -.76; P < .05) within this region. None of the five markers showed significant disequilibrium with the von Willebrand disease phenotype. The linkage disequilibrium/physical distance relationship was also analyzed as a function of chromosomal location for this and eight previously characterized regions. This analysis revealed a general trend in which linkage disequilibrium dissipates more rapidly with physical distance in telomeric regions than in centromeric regions. This trend is consistent with higher recombination rates near telomeres.

Alleles↗
PubMed1994

Genetic structure of the Utah Mormons: comparison of results based on RFLPs, blood groups, migration matrices, isonymy, and pedigrees.

The genetic structure of the Utah Mormon population is examined using 25 blood group and 47 RFLP alleles obtained from 442 subjects living in 8 geographic subdivisions. Nei's GST was 0.013 (p < 0.002) for the RFLP data and 0.012 (p > 0.4) for the blood group data, showing that only 1% of the genetic variance in this population can be attributed to subdivision effects. A comparison of intersubdivision distance matrices based on blood groups, RFLPs, migration matrices, isonymy, and pedigrees shows that genetic distances have relatively low and nonsignificant correlations with the other three types of data. However, the correlations based on RFLPs are considerably higher than those based on blood groups. Relationship matrices based on interindividual allele sharing were compared with known genealogical kinship coefficients between each pair of individuals. The correlation between the blood group and RFLP relationship matrices was small but marginally significant using the Mantel test (r = 0.014, p < 0.06). The RFLP relationship matrix correlated more highly with genealogical kinship than did the blood group relationship matrix (r = 0.023, p < 0.0001 and r = 0.012, p < 0.001, respectively). These correlations increased by approximately one order of magnitude when pairs of subjects having zero kinship coefficients were excluded. These results show that genetic distances derived from RFLPs correlate more strongly with other types of kinship than do distances based on blood groups. This probably reflects the fact that RFLPs are more neutral, have frequencies that are more accurately estimated, and contain more information about DNA sequence variation.

Blood Group Antigens↗
PubMed1994

Founder effect: assessment of variation in genetic contributions among founders.

We present a Monte Carlo method for determining the distribution of founders' genetic contributions to descendant cohorts. The simulation of genes through known pedigrees generates the probability distributions of contributed genes in recent cohorts of descendants, their means, and their variances. Genealogical data from three populations are analyzed: the Hutterite population of North America, the island population of Sottunga from the Aland archipelago, and the large Utah Mormon population. Two applications of the Monte Carlo method are presented. First we investigate the relative opportunity for founder effect in the three populations, which have dissimilar pedigree structures and dissimilar disease gene frequencies. Second, we measure the reproductive success of population founders in terms of the number of genes they contribute to a cohort some number of generations descendant and compare the effects of polygyny versus monogamy on reproductive success. The distribution of Hutterite founder contributions describes the context for a classic founder effect. Hutterite founders have a higher probability of leaving no genes in the population (72%) than Sottunga (48%) and Mormon (48%) founders. However, founder genes that survive among Hutterite descendants do so in larger numbers on average than founder genes in the other two populations. Greater variation among monogamous Hutterite founders compared with Mormon polygynous founders demonstrates that polygyny alone does not maximize the variance in reproductive success; other population characteristics are at least as important for determining variability among individuals in their genetic contributions to a gene pool. Our findings make it difficult to appreciate the reproductive advantage of polygyny in the Mormon population. Although the expected gene contributions and their variances were larger for polygynous founders compared with other Mormons, the main effect of polygyny was to increase the probability that any polygynist left a few genes among descendants. Furthermore, only 12% of the variation in the genetic contributions of Mormon founders is explained by their number of offspring. We conclude that shallow genealogical data (from one or a few generations) provide a poor measure of long-term reproductive success.

Alleles↗