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Biomedical subjects

L Costello

Publications and source records attributed to L Costello.

17 recordsLinked to original sources
PubMed2001

Myopia and night-time lighting during sleep in children and adults.

This cross-sectional study investigated the relationship between different lighting conditions experienced during sleep in the first -two years of life and development of myopia after age two as reported retrospectively by parents in a total of 469 individuals, including 252 children aged 2-16 yr., and 217 adults aged 17-40 yr. There were no significant differences in incidence of myopia in children who had slept from 0-2 yr. in darkness, with a night light, room light, or hall light. Adults who were reported by their parents to have slept with a night light on from 0-2 yr. were significantly more likely to be myopic than those who were reported to have slept from 0-2 yr. in any other lighting condition.

Adolescent↗
PubMed1998

Two distinct types of fatty acid-binding protein are expressed in heart ventricle of Antarctic teleost fishes.

This report provides the first evidence for the existence of two distinct types of fatty acid-binding protein (FABP) in cardiac tissue of vertebrates. Four species of Antarctic teleost fish (Chaenocephalus aceratus, Cryodraco antarcticus, Gobionotothen gibberifrons and Notothenia coriiceps) exhibited two FABP mRNAs of 1. 0 kb and 0.8 kb, which we have termed Hh-FABP and Had-FABP (isolated from Heart tissue, with similarity to mammalian heart-type FABP or mammalian adipose-type FABP respectively). These FABP types appear to be products of distinct genes. Both FABP transcripts were abundant in cardiac and aerobic pectoral muscle. However, relative abundance of the two types varied distinctly among other tissues such as kidney, brain, spleen and white muscle. Neither FABP type was expressed in liver or intestine. The coding regions of Hh-FABP and Had-FABP cDNAs from the same species are only approximately 60% identical with one another. However, homologues of each FABP species, which exhibit >98% identity to their respective types, were isolated from three other Antarctic teleosts. Phylogenetic analysis of aligned amino-acid sequences places Hh-FABP with other vertebrate heart-type FABPs, and Had with adipose/cutaneous FABPs. Expression of two distinct FABPs in cardiac tissue of Antarctic teleosts may be related to their ability to both utilize fatty acid as the primary metabolic fuel and to store lipid intracellularly.

Amino Acid Sequence↗
PubMed1997

Variable expression of myoglobin among the hemoglobinless Antarctic icefishes.

The important intracellular oxygen-binding protein, myoglobin (Mb), is thought to be absent from oxidative muscle tissues of the family of hemoglobinless Antarctic icefishes, Channichthyidae. Within this family of fishes, which is endemic to the Southern Ocean surrounding Antarctica, there exist 15 known species and 11 genera. To date, we have examined eight species of icefish (representing seven genera) using immunoblot analyses. Results indicate that Mb is present in heart ventricles from five of these species of icefish. Mb is absent from heart auricle and oxidative skeletal muscle of all species. We have identified a 0.9-kb mRNA in Mb-expressing species that hybridizes with a Mb cDNA probe from the closely related red-blooded Antarctic nototheniid fish, Notothenia coriiceps. In confirmation that the 0.9-kb mRNA encodes Mb, we report the full-length Mb cDNA sequence of the ocellated icefish, Chionodraco rastrospinosus. Of the eight icefish species examined, three lack Mb polypeptide in heart ventricle, although one of these expresses the Mb mRNA. All species of icefish retain the Mb gene in their genomic DNA. Based on phylogeny of the icefishes, loss of Mb expression has occurred independently at least three times and by at least two distinct molecular mechanisms during speciation of the family.

Amino Acid Sequence↗
PubMed1997

Conservation of the myoglobin gene among Antarctic notothenioid fishes.

We determined the myoglobin cDNA sequence for seven Antarctic notothenioid fish species. These data identify mutations in the myoglobin gene for Champsocephalus gunnari and Pagetopsis macropterus, two icefish species that lack detectable quantities of the polypeptide but express myoglobin mRNA. a third species lacking myoglobin polypeptide, Chaenocephalus aceratus, is devoid of myoglobin mRNA and accordingly failed to produce myoglobin products on polymerase chain reaction (PCR) amplification. Myoglobin cDNA sequences were highly conserved among the species the express the protein, particularly in the coding region. Sequence variation among the myoglobin-expressing channichthyid species was 2.0% to 2.9% in the coding region and 2.6% to 3.3% over the entire cDNA. The same extent of variation, 1.6% to 3.2% in the coding sequence and 2.8% to 3.7% overall, was observed between the icefishes and more distantly related, red-blooded nototheniid species. The two species expressing mutant myoglobin mRNA, C. gunnari and P. macropterus, exhibited the highest degree of sequence variation among the fish myoglobins examined. Drift in the myoglobin sequence in these two species, and conservation of myoglobin cDNA among fishes from two distinct families, suggest that a selective pressure operates to maintain myoglobin in the species that express the protein.

Amino Acid Sequence↗
PubMed1991

Shaping up.

EMS administrators across the country are turning couch potatoes into lean, mean rescuing machines. Is your squad physically fit?

Adult↗
PubMed1990

Unilateral carotid artery ligation in the Mongolian gerbil as a model for testing infarction-reducing therapies.

This study evaluates infarct size measurement as an indicator of cerebral ischaemia outcome in a placebo-controlled trial of potential cerebral protection in the unilateral carotid artery ligation in the Mongolian gerbil. Ibuprofen was used in an effort to manipulate infarct size as this agent has been shown to reduce ischaemia in myocardial infarction. Using measurements obtained through an infarct-sizing technique and a statistical power analysis of the method, the sample sizes needed to obtain significant results were projected for this model. In this case, it was not possible to demonstrate an effect of ibuprofen on infarct size although a tendency towards larger infarct size in ibuprofen-treated compared with placebo-treated gerbils was observed (36.1 +/- 10.1% versus 30.0 +/- 17.5%). The sample sizes needed to find significant changes in infarct size indicate that this model finds a practical use in studying therapies which will alter infarct size by at least 50%. For example, to detect a 30% change in infarct size, 33 successfully infarcted gerbils per group would be needed, but a 50% change would require a more tenable 13 infarcted gerbils per group. However, given the 40% infarction rate of occluded gerbils seen in this study, almost 33 gerbils per group would be required to detect a 50% change. In addition, somatosensory evoked potential was compared with neurological examination as a predictor of infarction. It would be helpful to be able to pre-screen for infarcted gerbils immediately after occlusion in order to direct infarcted gerbils into control and treated groups. Somatosensory evoked potential successfully predicted infarction with a 90% accuracy in 21 gerbils compared with neurological evaluation which was 100% accurate. But the somatosensory evoked potential prediction was made within 15 min of occlusion as opposed to the 6 h of observation during which the neurological evaluation was made.

Animals↗
PubMed1990

Easter parade.

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Commerce↗
PubMed1984

Mechanisms of Ca2+ transport in plasma membrane vesicles prepared from cultured pituitary cells. I. Characterization of Na+/Ca2+ exchange activity.

GH3 rat anterior pituitary cells possess a Na+/Ca2+ exchange transport mechanism which is present in purified plasma membrane vesicles prepared from these cells. Imposition of an outwardly directed Na+ gradient in vesicles results in a marked concentrative uptake of Ca2+ which is abolished by the Ca2+ ionophore A23187. Transport activity depends on a sustained Na+ gradient. Dissipation of the driving force by treatment with Na+ ionophores or by passive gradient collapse abolished transport activity. The exchange reaction is completely reversible since addition of extravesicular Na+ enhances Ca2+ efflux from Ca2+ loaded vesicles. A kinetic analysis of Na+/Ca2+ exchange indicates saturation kinetics for both substrates with apparent values of Km for Na+ and Ca2+ of 17 mM and 5 microM, respectively, and a Vmax of about 8 nmol/min/mg of protein for Ca2+ uptake at 25 degrees C. In addition to Na+/Ca2+ exchange, the transporter functions in a Ca2+/Ca2+ exchange mode with an apparent Km of 20 microM and Vmax of 16 nmol/min/mg of protein for Ca2+ influx. Na+/Ca2+ exchange is not inhibited by protonophores indicating that Ca2+ flux does not occur via coupled Na+/H+, Ca2+/H+ exchange. Transport is inhibited by derivatives of the pyrazine diuretic amiloride. The pH dependency of Ca2+ uptake displays a sigmoidal relationship with stimulation of activity at alkaline pH and inhibition at acid pH. Furthermore, the reaction is electrogenic (i.e. more than 2 Na+ transported per Ca2+) as demonstrated by stimulated uptake of lipophilic cations during exchange and by effects of artificially imposed membrane potentials on the rate of Ca2+ transport. Plasma membrane vesicles prepared from bovine anterior pituitary glands also display Na+/Ca2+ exchange with many of the same characteristics. These results support the notion that Na+/Ca2+ exchange functions in Ca2+ homeostasis in pituitary cells.

Amiloride↗