Apolipoprotein epsilon 4 and coronary artery disease.
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Apolipoprotein E4↗
Biomedical subjects
R G Murray
Publications and source records attributed to R G Murray.
Serum cortisol levels predict infarct size and patient mortality.
We have investigated prospectively the serum cortisol response to acute myocardial infarction in 70 consecutive patients admitted to a coronary care unit and we have shown that the levels are significantly raised early in the course of the illness and prior to elevation of the cardiac specific enzyme fraction, creatine kinase MB. The magnitude of the cortisol response is related to the size of the ensuing infarction (rs = 0.54) as calculated from the total creatine kinase MB release (P < 0.001) and very high levels (> 2000 mumol/l) are predictive of mortality (P < 0.05). Serum cortisol levels may have a role in the early identification of myocardial infarction and in predicting those patients with a poor prognosis.
Anistreplase↗
Acute and chronic hemodynamic effects of xamoterol in mild to moderate congestive heart failure.
Xamoterol, a new beta 1 partial agonist, has the potential to modulate cardiac response to variations in sympathetic tone in patients with heart failure. Its properties should result in beta-receptor stimulatory effects at low levels of sympathetic tone and beta-receptor protective effects at higher levels of sympathetic tone. The acute effects of intravenous (i.v.) xamoterol on hemodynamics at rest and during exercise were studied in 30 patients with mild to moderate heart failure (13 patients in New York Heart Association class II; 17 in class III) due to ischemic (n = 24) or cardiomyopathic (n = 6) heart disease. Cardiac index, stroke volume and stroke work index at rest were significantly improved after i.v. administration of xamoterol and consistent with net agonist effects. During exercise, heart rate and double product were significantly reduced (net antagonist effects), but with preservation of the expected increases in cardiac index and systolic blood pressure. These hemodynamic findings confirm the ability of xamoterol to modulate cardiac response to variations in sympathetic tone. Tachyphylaxis and arrhythmogenicity limit the chronic use of drugs with full beta-agonist properties as positive inotropes in heart failure. The patients were therefore entered into a 6-month double-blind, placebo-controlled, crossover study of chronic oral xamoterol therapy, 200 mg twice daily, and the hemodynamic responses to i.v. xamoterol were repeated at the end of the trial. No impairment in either resting or exercise effects was observed, indicative of a maintained response and absence of tachyphylaxis after chronic therapy. Furthermore, 24-hour ambulatory electrocardiographic monitoring showed no change in ventricular arrhythmias during oral treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenergic beta-Agonists↗
DNA polymorphisms in new isolates of 'Deinococcus radiopugnans'.
Nineteen new Deinococcus isolates from soil, 18 of which were from samples immediately adjacent to a lake in Nottingham, UK, were characterized by conventional criteria, and found to be identical to each other and to conform most closely to the species D. radiopugnans. However, we detected three different restriction enzyme activities in three different isolates. Because of this suggestion of heterogeneity, we examined the isolates for restriction fragment length polymorphisms (RFLPs). RFLP analysis of the 19 original isolates, using three different probes, distinguished 17 divergent groups. This extraordinary diversity cannot be attributed to geographical differences, nor to the method of isolation, which employed UV-radiation selection.
Blotting, Southern↗
A correlation of phylogenetic diversity in the Proteobacteria with the influences of ecological forces.
The Proteobacteria are physiologically and morphologically diverse, although they form a coherent set of four main lineages on phylogenetic analysis of ribosomal RNA. A rational and consistent taxonomic arrangement bringing today's phenotypic and phylogenetic conclusions about them into register is not yet possible. It is also difficult to understand the selective forces involved in their evolution that fostered such diversity. This latter problem is addressed in this essay and is based on the assumption that bacterial evolution could only have occurred in ecological consortia whose products of metabolism modified the environment, provided nutrition, and have a basis for selection of new capabilities.
Bacteria↗
The significance of the abnormal rest thallium-201 myocardial image in coronary artery disease.
Rest Thallium-201 myocardial images were abnormal in 20 out of 40 patients with arteriographically proven coronary artery disease. The myocardial image appearances did not accurately reflect the extent of coronary artery disease present. However, in 35 of the 40 patients (88%) the presence or absence of abnormalities on the rest myocardial image correleted respectively with the presence or absence of abnormal wall motion at left ventriculography. Most rest image abnormalities could be attributed to previous myocardial infarction, but in six patients myocardial ischaemia was possibly the cause. These results suggest that though myocardial fibrosis is usually the cause of rest myocardial image abnormalities in coronary artery disease, this is not invariably so. The possible therapeutic implications are discussed.
Adult↗
ST isopotential precordial surface maps in patients with acute myocardial infarction.
ST amplitude distributions were studied in 41 patients with acute myocardial infarction by deriving isopotential maps from a 5 x 7 electrode precordial matrix. Independent data on infarct size and localization were obtained utilizing the technetium 99m stannous pyrophosphate scintigraphic method. The locus of maximal ST elevation was stable for at least two days in 86% of 27 patients with anterior infarction. A single maximum or maximum-minimum was found in 88% but 22% of the patients had multiple maxima and/or minima in at least two maps. Areas of significant ST elevation were often excluded from the precordial matrix. The site of maximal ST elevation correlated with scintigraphic infarct site but was displaced medially in lateral infarction. The relation between infarct size and sigmaST elevation was significant and curvilinear. sigmaST underestimated size in large anterior infarction. The correlation of the size and the number of sites with ST elevation greater than or equal to 1.5 mm was weak (r = 0.56). The degree of ST abnormality in 14 patients with inferior infarction decreased significantly during the initial 24 hours. The isopotential maps were similar to those obtained in anterior infarction but the polarity was reversed. The results provide limited support for the continued exploration of ST analysis as a clinical method but suggest that sizing methods should be based on total body surface mapping, taking into account the geometry and electrical properties of the torso.
Action Potentials↗
Evaluation of thallium-201 exercise scintigraphy in coronary heart disease.
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Adult↗
Effects of some platinum IV complexes on cell division of Escherichia coli.
A comparison was made of the effects of cis-tetrachlorodiaminoplatinum (IV) (cis-TCDPt), rans-TCDPt), and hexachloroplatinum (HCP) on growth and cell division of Escherichia coli strains D21 and D22. At or below 40 microgram/mL, cis-TCDPt inhibited cell division but not growth, DNA, or protein synthesis, although areas of increased electron density could be demonstrated in treated cells. In contrast, 40 microgram/mL of trans-TCDPt or HCP inhibited growth. Trans-TCDPt-treated cells developed condensed nucleoids; HCP-treated cells showed no obvious cytological changes to correlate with growth inhibition. Combination of cis-TCDPt with nalidixic acid, both at one-half the lowest filament-forming concentrations, resulted in formation of filaments, suggesting an additive effect. Combination of cis-TCDPt followed by ampicillin on E. coli B/r resulted in single bulges near the center of the filaments. Cis-TCDPt could therefore inhibit an initial step in the septation sequence, possibly at the level of the regulation of the hydrolytic enzymes. Whether cis-TCDPt exerts its effect by interreaction with DNA or with a membrane target is still uncertain.
Ampicillin↗
Early cardiovascular adaptation to simulated zero gravity.
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Adaptation, Physiological↗
Can the extent of coronary artery disease be predicted from thallium-201 myocardial images?
The accuracy with which the extent of coronary artery disease can be predicted from stress thallium-201 myocardial images has been assessed in 81 patients with chest pain. Whereas the appearance of the myocardial images was both a sensitive means of detecting coronary artery disease (images abnormal in 43 of 47 patients with abnormal coronary arteriograms) and specific in excluding it (images normal in 31 of 34 patients with normal arteriograms), there was poor correlation between the extent of disease predicted from the Tl-201 images and the findings at arteriography. It is concluded that although stress Tl-201 myocardial imaging is a useful method for the noninvasive diagnosis of coronary artery disease, it cannot be relied upon to predict the number of abnormal vessels.
Adult↗
A quantitative approach to the analysis of the normal thallium-201 myocardial image.
The visual interpretation of Thallium-201 myocardial images is made more difficult by nonhomogeneity of myocardial tracer uptake in normal studies. To increase the objectivity of the study, the variation in count density in different myocardial areas has been calculated using a computer regions of interest technique in 14 healthy, young subjects following intravenous injection of the radionuclide at rest and in 10 after injection during maximal exercise. The "normal ranges" for regional Thallium-201 uptake so obtained are presented and discussed.
Adult↗
Magnesium metabolism in patients with coronary heart disease.
1. The oral absorption of magnesium, its myocardial uptake and exchangeable magnesium have been studied in patients with coronary heart disease and controls using the radioactive isotope magnesium-28. 2. No significant difference in oral absorption or myocardial uptake was found between patients and controls. 3. The exchangeable magnesium per kg body weight was significantly lower in the patients than in the controls.
Adult↗
Protein-lipid-lipopolysaccharide association in the superficial layer of Spirillum serpens cell walls.
The backing layer of the Spirillum serpens VHA cell wall, which supports and is bonded to the outer, structured protein layer, was isolated and shown to be similar in composition to the same elements of the outer membrane. It contained a lipopolysaccharide that was similar, but not identical, to that of the intact wall and the same phospholipids. The interaction of the isolated wall lipopolysaccharide with the loosely bound wall lipids provided lamellae, whose surfaces were an effective template for a lifelike reassembly of the isolated outer-layer hexagonal protein in the presence of Ca2+. Assembly did not take place on pure lipopolysaccharide, which dispersed in differing forms. A lipid-lipopolysaccharide-water interface appeared to be required as a template surface for the assembly. Lipopolysaccharide from Pseudomonas aeruginosa was able to replace that of S. serpens in the template. These observations suggest that lipid-lipopolysaccharide complexes are highly ordered, and this order is important to the nucleation and assembly of the protein array.
Bacterial Proteins↗
Cell envelope associations of Aquaspirillum serpens flagella.
Specific regions of the cell envelope associated with the flagellar basal complex of the gram-negative bacterium Aquaspirillum (Spirillum) serpens were identified by studying each of the envelope layers: outer membrane, mucopeptide, and plasma membrane. The outer membrane around the flagella insertion site was differentiated by concentric membrane rings and central perforations surrounded by a closely set collar. The perforations in both the outer membrane and the isolated mucopeptide layer were of a size accomodating the central rod of the basal complex but smaller than either the L or the P disks. The P disk of the complex may lie between the mucopeptide and the outer membrane. Electron microscopy of intact, spheroplasted, or autolyzed preparations did not adequately resolve the location of the inner pair of disks of the basal complex. Freeze-etching, however, revealed differentiation within the plasma membrane that appeared to be related to the basal complex. The convex fracture face showed depressions which are interpreted as impressions of a disk surrounded by a set of evenly spaced macromolecular studs and containing a central "plug" interpreted as the central rod. In thin sections, blebs, which appear to be associated with the flagellar apparatus, were seen on the cytoplasmic side of the plasma membrane. Superimposing the dimensions of the flagellar basal complex and the spacings of the cell envelope layers and using the position of the L disk within the outer membrane for reference, showed that the S disk might be within and the M disk beneath the plasma membrane. A tentative model was developed for comparison with that based on the structure of the Escherichia coli basal complex.
Bacteriolysis↗
The envelope of Micrococcus radiodurans: isolation, purification, and preliminary analysis of the wall layers.
Two methods are presented that separate the complex envelope of Micrococcus radiodurans, strain Sark, into its constituent layers. The first involved treating whole cells with 0.025 M Tris buffer (pH 7.5) containing 2 mM of calcium and 3 mM of magnesium, resulting in the degradation of an intermediate ('compartmentalized') layer and consequent sloughing of the outer subunit and interior layers to form vesicles. This treatment also appears to show that the interior layer may be connected with the peptidoglycan-containing 'holey' layer. The second method involves treating whole cells with benzene followed by sonication; the results suggested that this treatment only released the outer layers from the 'compartmentalized' layer and did not degrade layers. Following benzene treatment, digestion of the 'compartmentalized' layer with cold sodium dodecyl sulfate (SDS) released the 'holey' layer. Electrophoretic analysis of some of the isolated layer preparations suggested that the subunit layer consisted of three major proteins of 90 000, 92 000, and 94 000 molecular weight, one minor protein of 100 000, a small amount of carbohydrate associated with the 94 000 protein, and a small amount of a 55 000 lipoprotein. The interior layer contained at least 10 proteins and may be attached to the peptidoglycan-containing 'holey' layer by means of the 55 000 lipoprotein.
Cell Fractionation↗