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Biomedical subjects

I Wilson

Publications and source records attributed to I Wilson.

At least 91 records · Page 5Linked to original sources
PubMed1985

Size of spleen rather than amount of platelet sequestration may determine long term responses to splenectomy in adult idiopathic thrombocytopenic purpura.

Fourteen adults with idiopathic thrombocytopenic purpura suffered a relapse after treatment with steroids, vinca alkaloids, or intravenous gammaglobulin. Splenic sequestration of platelets labelled with 111In-oxine was assessed, and the patients then underwent splenectomy. During follow up of four to 47 months (mean 20.7) none of the patients required further treatment, including three of 14 who showed partial relapses. Splenic sequestration patterns did not predict relapses, but an unexpected finding was that patients who relapsed had significantly smaller spleens. It is concluded that splenectomy is beneficial in most adult patients with idiopathic thrombocytopenic purpura and that radiological techniques to measure the size of the spleen may be useful in predicting which patients may relapse.

Adolescent↗
PubMed1984

Immediate care.

Explore the source record for details and available documents.

Aircraft↗
PubMed1984

Cis-trans isomerization of the (5-nitro-2-furyl)acrylamide, AF-2, initiated by ascorbate, glutathione, Fe(II) and OH-.

The cis-trans isomerization of the (5-nitro-2-furyl)acrylamide, AF-2, has been investigated using some important biological reducing agents to initiate reaction. Physiological concentrations of L-ascorbic acid, glutathione and iron(II) all accomplish isomerization in a catalytic manner over a period of minutes. Base-catalysed isomerization has also been observed. In all cases, the presence of oxygen severely inhibits isomerization. It is proposed that the mechanism involves a free-radical chain process; AF-2 or analogues are thus extremely sensitive probes for the generation of nitro radicals in biochemical reducing systems because of the high efficiency of isomerization.

Ascorbic Acid↗
PubMed1983

Heme models of peroxidase enzymes: deuteroferriheme-catalyzed chlorination of monochlorodimedone by sodium chlorite.

The iron(III) complex of deuteroporphyrin(IX), deuteroferriheme, catalyzes the chlorination, by sodium chlorite, of the active methylene compound monochlorodimedone (MCD) to dichlorodimedone. Rate studies, carried out on a stopped-flow spectrophotometric time scale, show the chlorination to be zero-order in MCD, first-order in ClO2- and to display a complex dependence on heme. The active chlorinating agent is believed to be hypochlorite, OCl-, formed as a result of the initial two-electron oxidation of heme to peroxidatic intermediate by chlorite ion. This scheme is supported by the fact that the normal (4:1) heme:ClO2- molar stoichiometry is reduced in the presence of MCD to values approaching 2:1. This suggests that MCD is an effective scavenger of OCl-, which, in the absence of active methylene compound, serves as a two-electron oxidant of heme. The zero-order dependence of rate on MCD is attributed to the slow formation of OCl-, consequent to a mechanism in which the rate-limiting step is viewed to be the regeneration of free heme from peroxidatic intermediate, probably via a catalatic pathway. Support for such a mechanism is provided by the fact that addition of ascorbate greatly enhances the rate of MCD chlorination, presumably by accelerating the rate of heme regeneration via perioxidation reduction of the heme intermediate.

Chlorides↗
PubMed1982

Peroxidase-like activities of iron(III)-porphyrins: kinetics of the reduction of a peroxidatically active derivative of deuteroferriheme by phenols.

The kinetics of reduction of a peroxidatically active intermediate (formed by reaction of deuteroferriheme with hydrogen peroxide) by phenol and a series of substituted phenols have been studied by stopped-flow spectrophotometry. The complex effects of varying heme concentration have been interpreted in terms of the formation of a dimeric form of the intermediate by reaction of monomeric intermediate with unoxidized ferriheme monomer. Both the relative reactivity of phenols towards the two forms of the intermediate and the rate constants for reduction of intermediate are markedly influenced by phenol substituents. Effects of pH suggest that phenolate anions are the reactive forms of the reductants. Rate constants for the monomeric intermediate reactions (kDFH) are related to those (kHRP) for the corresponding reductions of horseradish peroxidase Compound I by the following relation: log kDFH = 1.53 log kHRP -3.74.

Heme↗
PubMed1979

Theory and practice in the measurement of laterality.

Using data from a divided visual field task, it is shown that correlations between laterality measures and overall accuracy are not a consequence of the level of accuracy constraining the achievable range of laterality, but depend on the design of current laterality measures and on the differential correlation of each hemisphere's scores with total accuracy. Comparing four laterality measures on 125 subjects shows that, although the laterality distributions differ in dispersion, the four measures are significantly intercorrelated and give nearly identical indications of average lateralisation. It is concluded that laterality measures may be of some limited use in comparing experimental results from different sources rather than in evaluating theories of cerebral asymmetry.

Adolescent↗
PubMed1978

Strategic planning for marketers.

The merits of strategic planning as a marketing tool are discussed in this article which takes the view that although marketers claim to be future-oriented, they focus too little attention on long-term planning and forecasting. Strategic planning, as defined by these authors, usually encompasses periods of between five and twenty-five years and places less emphasis on the past as an absolute predictor of the future. It takes a more probabilistic view of the future than conventional marketing strategy and looks at the corporation as but one component interacting with the total environment. Inputs are examined in terms of environmental, social, political, technological and economic importance. Because of its futuristic orientation, an important tenant of strategic planning is the preparation of several alternative scenarios ranging from most to least likely. By planning for a wide-range of future market conditions, a corporation is more able to be flexible by anticipating the course of future events, and is less likely to become a captive reactor--as the authors believe is now the case. An example of strategic planning at General Elecric is cited.

Commerce↗
PubMed1976

A comparison of live and videorecord viewing of infant behavior under sound stimulation. III. Six-month-old babies.

Ten clinically normal 6-month-old infants were presented with a series of sound stimuli while their behavior was simultaneously videotaperecorded and assessed live by 2 sound-masked observers. Two weeks later the same observers assessed the behavior from the videorecords. In both situations observers were permitted to see the babies for 13 sec at each trial. The first 5 sec formed a prestimulus observation period and the following 8 sec possibly contained a sound stimulus. Between trials the observers were allowed 20 sec in which to not (1) prestimulus activity, (2) confidence in response, and (3) facial, digit, and limb movements and "wholistic"impressions (e.g., "stilling"). The agreement between the live and video situations was modest for prestimulus activity and confidence in response, and fair to good for movement item. The outcome was rather similar to that of our earlier work on neonates and 6-week infants, although it did suggest a small loss of information with the videorecording of 6-month infants.

Acoustic Stimulation↗
PubMed1976

Studies in infant behavioural audiometry. I. Neonates.

The behaviour of 93 clinically normal neonates was video-recorded while they were presented with sequences of sound stimuli which varied in sound pressure level, bandwidth and rise time and which included two voice signals and a no-sound (control) trial. Video records were made both for the whole body aspect and for a 3 1/2 X "close-up" of the head. Later, the video records were shown to 6 observers who were allowed to see the babies for 10 sec at each trial. The first 5 sec was a pre-stimulus observation period, and the second 5 sec usually contained a sound stimulus. Between the trials, the observers were given 20 sec in which to record (1) pre-stimulus activity, (2) confidence in response, and (3) movement details (data for (3) not reported here). For the whole-body aspect, observers were allowed to see (1) the whole body, (2) the head, arms and trunk, (3) the arms, trunk and legs, (4) the head only, (5) the arms and trunk only, or (6) the legs only, during different viewing sessions. For the head aspect, they could see (7) the whole head, (8) the head above the upper lip, or (9) the head below the upper lip. This segmentation was achieved by masking parts of the television screen with shutters. The response confidence ratings were analysed using aspects of signal detection theory to show differences amongst various body segments (p less than 0.001), sound pressure levels (p less than 0.001), bandwidths (p less than 0.001), and rise times (p less than 0.01). There were significant interactions between sound pressure level X bandwidth (p less than 0.001), sound pressure level X rise time (p less than 0.01), and bandwidth X rise time (p less than 0.001). A 90-dB broad-spectrum noiseband was by far the most effective stimulus. The response to different sound stimuli was differentially affected by pre-stimulus activity state. The results are discussed in relation to recent work on clinical screening techniques.

Acoustic Stimulation↗
PubMed1975

A comparison of live and videorecord viewing of infant behavior under sound stimulation. II. Six-week-old infants.

Ten clinically normal 6-week old infants were presented with a series of sound stimuli while their behavior was assessed live by 2 sound-masked observers and simultaneously videorecorded. Two weeks later the same observers assessed the behavior from the videorecords. In both situations, observers were permitted to see the babies for 10 sec at each trial. The first 5 sec was a prestimulus observation period, and the second 5 sec might have contained a sound stimulus. Between trials the observers were allowed 20 sec in which to note (1) prestimulus activity, (2) confidence in response, and (3) facial, digit, and limb movements, and "wholistic" impressions (e.g., "stilling"). The agreement between the live and video situations was fair for prestimulus activity, modest for confidence in response, and fair to good for movement items. The use of videorecorded material for 6-week old infants generally caused rather small losses of relevant information and apparently will not overly distort the findings of experimental or clinical work. This outcome was rather similar to that of our earlier study of neonates.

Acoustic Stimulation↗