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Biomedical subjects

J Grainger

Publications and source records attributed to J Grainger.

34 records · Page 2Linked to original sources
PubMed1991

Automatic letter priming in an alphabetic decision task.

An alphabetic decision task was used to study effects of form priming on letter recognition at very short prime durations (20 to 80 msec). The task required subjects to decide whether a stimulus was a letter or a nonletter. Experiment 1 showed clear facilitatory effects of primes being either physically or nominally identical to the targets, with a stable advantage for the former. Experiment 2 demonstrated that uppercase letters are classified more rapidly as letters (vs. non-letters) when they are preceded by a briefly exposed, forward- and backward-masked, visually similar uppercase letter than when they are preceded by a visually dissimilar uppercase letter. Finally, Experiment 3 demonstrated that nominally identical and visually similar primes facilitate processing more than do nominally identical, visually dissimilar primes. The alphabetic decision task proved to produce sensitive and stable priming effects at the feature, letter, and response-choice level. The present results on letter-letter priming thus constitute a solid data base against which to evaluate other priming effects, such as word-letter priming. The results are discussed in light of current activation models of letter and word recognition and are compared with data simulated by the interactive activation model (McClelland & Rumelhart, 1981).

Arousal↗
PubMed1990

A comparison of the haemodynamic and hypokalaemic effects of inhaled pirbuterol and salbutamol.

In this double blind study, the cardiovascular and hypokalaemic effects of equal doses of inhaled pirbuterol and salbutamol were compared in eight healthy volunteers. Increasing doses of 200, 400, 600 and 800 micrograms (total dose 2000 micrograms) were given from a metered dose inhaler at 15 min intervals, followed by measurement of heart rate, blood pressure, total electromechanical systole (QS2I) (as a measure of inotropic response) and plasma potassium (K+) concentration 15 min after each inhalation. After inhalation of the highest concentration, salbutamol resulted in a greater increase in heart rate (10.5 bpm vs 4.4 bpm, p less than 0.0007), and reduction in QS2I (-25.4 ms vs -9.6 ms, p less than 0.0001) than pirbuterol. There were no significant differences in changes in systolic blood pressure (1.9 mmHg vs 6 mmHg, p = 0.27), diastolic blood pressure (-5.8 mmHg vs -3.9 mmHg, p = 0.64) or plasma K+ (-0.21 mmol/L vs -0.15 mmol/L, p = 0.57). We conclude that the new beta-2 adrenergic agonist pirbuterol is at least as beta-2 selective as salbutamol when administered by repeated inhalation in healthy volunteers.

Administration, Inhalation↗
PubMed1990

Gas chromatographic and spectral properties of pentafluorobenzyl derivatives of 2,4-dichlorophenoxyacetic acid and phenolic pesticides and metabolites.

Eleven phenols and 2,4-dichlorophenoxyacetic acid, compounds that may be found in body fluids of humans exposed to pesticides, are derivatized with pentafluorobenzyl bromide and characterized by gas chromatography with electron capture detection. These derivatives are further characterized by positive and negative chemical ionization mass spectrometry, nuclear magnetic resonance spectroscopy, and gas chromatography-Fourier transform infrared spectroscopy. Negative chemical ionization mass spectra of all derivatives have an anionic base peak derived from the parent analyte. In the positive mode the nonchlorinated derivatives have base peaks indicative of the analyte, while chlorinated derivatives are cleaved to give the pentafluorobenzyl cation as base peak. The possibility is explored that ortho-substituted phenols might be formed as byproducts in these derivatizations.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1990

Case-control study of prescribed fenoterol and death from asthma in New Zealand, 1977-81.

A previous New Zealand case-control study of asthma deaths in the 5-45 year age group during 1981-3 found that prescription of fenoterol (by metered dose inhaler) was associated with an increased risk of death in patients with severe asthma. One major criticism of this study was that drug data for the cases and controls came from different sources. A new case-control design has been used to evaluate the same hypothesis, with a different set of asthma deaths, the same source for drug information being used for both cases and controls. This depended on identifying deaths from asthma during 1977-81 from national mortality records, and ascertaining which patients from those who died had been admitted to a major hospital for asthma during the 12 months before death. The study was confined to this subgroup, which accounted for about 20% of all asthma deaths in the areas served by a major hospital. For each of the eligible patients who died four age matched controls were selected from patients admitted to hospital for asthma during the year that the death occurred who had also had an admission for asthma in the previous 12 months. For the 58 cases and 227 control subjects information on prescribed drugs was collected from the hospital records relating to the previous admission. The odds ratio of asthma death in patients prescribed inhaled fenoterol was 1.99 (95% confidence interval 1.12-3.55, p = 0.02). As in the previous study, subgroups defined by markers of chronic asthma severity were also considered. The inhaled fenoterol odds ratio was 2.98 (95% CI 1.15-7.70, p = 0.02) in patients prescribed three or more categories of asthma drugs, 3.91 (95% CI 1.79-8.54, p less than 0.01) in patients with a previous admission for asthma in the past 12 months, and 5.83 (95% CI 1.62-21.0, p = 0.01) in patients prescribed oral corticosteroids at the time of admission. In patients with the most severe asthma (defined by a previous admission for asthma during the past 12 months and prescribed oral corticosteroids at time of admission) the inhaled fenoterol odds ratio was 9.82 (95% CI 2.23-43.4, p less than 0.01). These findings add further support to the hypothesis that inhaled fenoterol increases the risk of death in patients with severe asthma.

Administration, Inhalation↗
PubMed1990

Neighborhood frequency effects in visual word recognition: a comparison of lexical decision and masked identification latencies.

Recent research suggests that the time to recognize a visually presented word may be a function of the frequencies of orthographically similar words. More precisely, recognition latencies and errors appear to increase significantly as soon as the stimulus word is orthographically similar to at least one other higher frequency word. This phenomenon, referred to as the neighborhood frequency effect, was subjected to further experimental testing, using a larger selection of words of varying frequency and length, and using a new experimental technique that proved to be extremely sensitive to such effects. The results provide additional support for earlier observations of neighborhood frequency effects. It is also demonstrated that clear word-frequency effects do obtain when neighborhood frequency is held constant. The results support activation-based accounts of the word-recognition process.

Attention↗
PubMed1990

Priming word recognition with orthographic neighbors: effects of relative prime-target frequency.

Four lexical decision experiments were performed with an orthographic priming paradigm in which test words were preceded by orthographically related or unrelated prime words. When prime words were presented for 350 ms without a mask, it was observed that primes that are lower frequency orthographic neighbors of the target interfered with target processing relative to an unrelated condition. When primes were higher frequency neighbors of the target, no interference or facilitation was observed. On the other hand, with briefly presented masked primes, interference was observed with higher frequency prime words. Finally, facilitatory effects in masked repetition priming were obtained with both high- and low-frequency prime-target pairs. The results are interpreted in terms of activation and selection processes operating in visual word recognition.

Adult↗
PubMed1989

Chromatographic and spectroscopic properties of hemiacetals of aflatoxin and sterigmatocystin metabolites.

Improved fluorescence detection of aflatoxin B1 by chromatographic analysis is accomplished by conversion to the corresponding hemiacetal, aflatoxin B2a. Because the metabolites aflatoxin M1, aflatoxin P1, aflatoxin Q1, sterigmatocystin, and O-methylsterigmatocystin have the same molecular conversion site, we investigated the chromatographic and spectroscopic properties of hemiacetals of these compounds to assist in confirming aflatoxins and sterigmatocystins in human urine. Nuclear magnetic resonance and infrared absorbance were used to confirm the hemiacetal structure for aflatoxin B1 and sterigmatocystin. The ultraviolet absorbance, fluorescence, and chromatographic properties of the metabolites were investigated. Using these data, we optimized the detection and solvent conditions for high-performance liquid chromatography. We determined that, of the conditions studied, maximum sensitivity and resolution for the native aflatoxins were achieved with a mobile phase of methanol, tetrahydrofuran, and water, a C8 column in series with a C18 column, and fluorescence detection with 365 nm excitation and 430 nm emission wavelengths for aflatoxins B1 and M1 and with 500 nm emission wavelength for aflatoxins P1 and Q1. For the analysis of the hemiacetals, a mobile phase of methanol, acetonitrile, and water provided better chromatography and fluorescence detection. Sterigmatocystin and O-methylsterigmatocystin were readily converted to the hemiacetal forms, which, like the aflatoxins, were more polar and, therefore, earlier eluting by reversed-phase HPLC (methanol, acetonitrile, and water, 236 nm absorbance). These data are important to maximize the sensitivity and confidence for detecting the mycotoxin metabolites in biological specimens.

Acetals↗
PubMed1989

Structural identification of a heterocyclic compound implicated in the Spanish toxic oil syndrome.

The compound 1-phenyl-5-vinylimidazolidine-2-thione was previously reported to be the causative agent in the outbreak referred to as Spanish toxic oil syndrome. X-ray crystallography, together with nuclear magnetic resonance and infra-red spectroscopy, now show the correct structure of this compound to be N-(5-vinyl-1,3-thiazolidin-2-ylidene)phenylamine (5-VTPA). Data for the structural characterization of 5-VTPA and the closely related isomer N-(4-vinyl-1,3-thiazolidin-2-ylidene)phenylamine are reported.

Brassica↗
PubMed1989

On the role of competing word units in visual word recognition: the neighborhood frequency effect.

Current models of word recognition generally assume that word units orthographically similar to a stimulus word are involved in the visual recognition of this word. We refer to this set of orthographically similar words as an orthographic neighborhood. Two experiments are presented that investigate the ways in which the composition of this neighborhood can affect word recognition. The data indicate that the presence in the neighborhood of at least one unit of higher frequency than the stimulus word itself results in interference in stimulus word processing. Lexical decision latencies (Experiment 1) and gaze durations (Experiment 2) to words with one neighbor of higher frequency were significantly longer than to words without a more frequent neighbor. This neighborhood frequency effect is discussed in terms of the different types of candidate selection process postulated by contemporary models of visual word recognition.

Adult↗
PubMed1978

Covalent probe investigations with isolated central nerve myelin preparations.

The interaction of the covalently reacting probes dansyl chloride, fluorodinitrobenzene and trinitrobenzene sulphonic acid with isolated central nerve myelin sheath preparations has been studied. The three probes interact preferentially with accessible amino groups on lipid and protein in the membrane. With isolated myelin some 13% of the total phosphatidyl ethanolamine is labelled with dansyl chloride while the figure is 66% with fluorodinitro benzene and 47% with trinitrobenzene sulphonic acid. Lower levels of phosphatidyl serine are labelled. Phosphatidyl ethanolamine seems to be more accessible to probes in the myelin sheath than is phosphatidyl serine perhaps because the ethanolamine-containing lipid class is localised partially at the external apposition surfaces of the membrane which are most accessible to the probes. The serine phospholipids may not react so well because they are preferentially distributed at the cytoplasmic surface of the system. Analysis of protein labelling patterns after reaction of intact myelin with dansyl chloride indicates that the high molecular weight proteins and the proteolipid protein is accessible to the probe while the basic protein is not, even though this latter component is readily labelled with dansyl choride in purified form. It is suggested that the inability of the basic protein to react with myelin is perhaps due to the fact that it is occluded from interaction with the probe at the cytoplasmic apposition surfaces of the lamellae.

Animals↗
PubMed1975

The effects of fast neutrons on inoperable carcinoma of the stomach.

Thirty-nine unselected patients suffering from inoperable, recurrent, or residual adenocarcinoma of the stomach were referred for palliation with fast neutrons from the Medical Research Council's cyclotron at Hammersmith Hospital. A full course of 1440 rads given in 12 treatments over 26 days was administered to the patients. Because of the relatively low energy (7-5 MeV) of the beam from this particular machine, it was not possible to deliver the full dose uniformly throughout the tumour except in extremely thin patients. Pain, dysphagia, vomiting, and bleeding were relieved in the majority of cases. The side effects were minimal and easily controlled. Palpable masses disappeared. Five patients required surgery after neutron therapy. All the incisions were made through irradioated tissue and all except one healed normally. Tumour was present outside the treated area, but the absence of any palpable mass within the treated area was a consistent finding. Radiologically, the stomachs remained abnormal and later changes included gross mucosal abnormality and shrinkage. Fourteen patients came to necropsy and in 10 no tumour was present macroscopocally. Tumour cells were seen in all except two cases but these were few, surrounded by dense fibrous tissue, and may not have been viable. The remaining stomach was abnormal with a thickened wall and destruction of mucosa. Three of the four cases in which macroscopic tumour was present received less than the standard dose because of the inadequate penetration of the beam. Excellent regression of tumors was achieved by the neutrons, but the stomachs did not recover from this satisfactorily. Gastrectomy four to six months after treatment is therefore suggested. This operation and other surgical procedures in other patients were successfully carried out. There is a need for higher energy neutrons to improve treatment and extend it to patients of thick-set build.

Adenocarcinoma↗
PubMed1971

Jaundice due to iprindole.

Twenty-one patients treated for depression with iprindole developed evidence of liver damage: 15 were jaundiced, five had bilirubinuria, and one had pruritus. These complications occurred between four and 21 days after initial exposure to the drug. All patients recovered. Light and electron microscopic findings in liver biopsies of one of these patients were those of cholestasis without inflammation.

Adult↗