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Biomedical subjects

J Field

Publications and source records attributed to J Field.

At least 181 records · Page 10Linked to original sources
PubMed1978

The perception of solid form in early infancy.

Day and McKenzie determined the rate of habituation of fixation of young infants to repeated visual presentations of a cube. They found the habituation rate to be the same when the stimulus orientation changed between presentations as when it was fixed, and they interpreted this as evidence of shape constancy. However, a failure to discriminate between cubes in different orientations is only evidence of shape constancy if the infant can at the same time discriminate the cube from other cubelike forms. The experiment described here contrasted the rate of habituation of fixation of 12-week-old infants to a homogenous stimulus series (a cube presented in different orientations) with the rates of habituation to various heterogeneous series, in each of which a cube was alternated with some other solid. It was found that, while the infant could distinguish a cube from a photograph of a cube and a concave solid (an L-form), there was no evidence of discrimination between the cube and either a wedge or a truncated pyramid. The results imply limits to the young infants capacity to resolve solid form.

Discrimination Learning↗
PubMed1977

The mechanism of escape of plasma protein from small blood vessels in the mucosa of the small intestine of the rat.

A study has been made in rats of the relative rates of escape of plasma protein, measured by accumulation of Evans Blue, and of the large marker particle, HgS, into uninjured small bowel and into an area of intradermal injection of histamine. The rate of escape of Evans Blue, per unit mass of tissue, into small bowel and into an area of histamine-stimulated skin were found to be almost the same, but leakage of HgS into the bowel was only about 1/10 of leakage of the same tracer into a site of intradermal histamine injection. If it be assumed, as is generally accepted, that all the protein that leaks from histamine-stimulated vessels does so via gaps in vascular endothelium that are large enough to allow escape of large marker particles like HgS, these findings show that only a small fraction of the protein that leaks into normal intestinal mucosa can escape via gaps, and that most of the leakage must occur by a route not permeable to particles of HgS. The findings give no indication of the nature of the alternative route for escape of protein.

Animals↗
PubMed1977

A developmental study of the effects of instructions on visual shape judgements.

Previous developmental studies of visual shape judgements have failed to instruct subjects clearly as to the type of shape judgements required. Using the method of adjustment 180 subjects in five age groups, 6, 8, 10, 12 and 19 years, were instructed to judge either the real or projected shape of an elliptical standard slanted 39, 57 and 72 degrees from the fronto-parallel. No age changes were found in the tendency towards shape constancy. Objective shape judgements exhibited a significantly greater degree of constancy than projective judgements and there was no decline in constancy with increasing slant of the standard under objective instructions, in contrast to a marked decline under projective instructions. Female subjects consistently manifested a greater tendency towards shape constancy than males.

Adolescent↗
PubMed1977

Coordination of vision and prehension in young infants.

Infants aged 3, 5, and 7 months were shown solid objects and comparable intangible images of objects both within and beyond possible arm's reach. The infant's emotional reactions and reaching behavior in the presence of the image stimuli were very similar to their responses to the solid objects. The results do not support the reports of previous studies using a similar tactual-visual conflict situation that young infants become emotionally distressed when presented with discordant visual and tactual information. It was concluded that the initation of reaching attempts by young infants is predominantly visually controlled and any tactual-kinesthetic feedback from prehension seems to produce very little modification of young infants' reaching behavior.

Age Factors↗
PubMed1976

Oral terbutaline sulfate--amelioration of exercise-induced bronchospasm.

Bronchospasm can be induced in asthmatics when exercised according to a multistage branching treadmill protocol that allows them to achieve 80 per cent of their age-predicted maximal heart rate. This present study was undertaken to investigate the effect of oral terbutaline sulfate in ameliorating exercise-induced bronchospasm. Ten asthmatics were exercised, and FEV1.0 and MMEFR were assessed while standing, using a Jones Pulmonar II waterless spirometer at 5, 15, and 30 minutes after exercise. Three hours before exercise, the subjects received no medication, oral placebo, or 5 mg terbutaline sulfate orally. At all time intervals after exercise, the pulmonary function of the group pretreated with oral terbutaline was superior when compared to the no-medication group (P less than 0.01) and to the placebo-treated group (P less than 0.05). Oral terbutaline appeared to normalize the exercise tolerance of the asthmatics and restore physiologic pulmonary airway conductance by the parameters of FEV1.0 and MMEFR.

Administration, Oral↗
PubMed1976

Peripheral plasma determinations of prostaglandin E in asthmatics.

Prostaglandins, unsaturated fatty acid derivatives with diversified pharmacologic activity, have recently been implicated in the pathophysiology of reversible airway disease. This study attempted to elucidate baseline prostaglandin E (PGE) plasma levels in asthmatics and the change in these levels after stimulation by a beta-adrenergic agent. Fourteen stable, ambulant patients with reversible airway disease and 28 nonatopic control subjects were studied. All had baseline PGE levels performed. The asthmatics were asked to abstain from all medication for 10 hr prior to evaluation. After baseline evaluation consisting of plasma PGE determination, pulmonary function test, blood pressure, and heart rate, 375 mug of aerosolized terbutaline sulfate was administered to 8 of the asthmatics plus 4 of the nonatopic control subjects; the above measurements were repeated at 15, 30, and 60 min after administration. There was a statistically significant difference in baseline plasma PGE levels between the asthmatics (PGE = 432 +/- 81) and the nonatopic control subjects (PGE = 89 +/- 9) (p less than 0.002). Following terbutaline administration, there was no significant change observed in PGE levels in asthmatic or in control individuals (asthmatics: 0 min, 570, 15 min, 513, 30 min, 514, 60 min, 608; normal subjects: 0 min, 138, 15 min, 137, 30 min, 143, 60 min, 214). In summary, we observed a significant difference in baseline PGE levels between asthmatic and nonatopic control persons. No change, however, was noted in PGE levels after beta-adrenergic receptor stimulation. This observation is consistent with the current hypothesis that beta-adrenergic agents act independently of prostaglandins to increase adenyl cyclase and modify bronchiole smooth muscle tone.

Adult↗
PubMed1976

Evaluation of exercise-induced bronchospasm in the adult asthmatic.

It has been shown that most asthmatics respond to exercise with bronchospasm. This study was undertaken to develop a safe and reliable method for quantifying exercise-induced bronchospasm in the asthmatic adult. Five normal adult volunteers and 12 stable asthmatics were exercised to 80% of their predicted maximal heart rate according to a multistage branching treadmill protocol. Their responses in terms of forced expiratory volume in 1 sec (FEV1) and maximum midexpriatory flow rate (MMEFR) at 5, 15, and 30 min after exercise were assessed, while standing, with a Jones Pulmonar II waterless spirometer. This submaximal stress test was chosen because 80% of predicted maximal heart rate could be obtained by all individuals and allowed the asthmatics to exercise long enough for inducible bronchospasm to occur. Audible wheezing was induced in 100% of the asthmatics and in none of the nonasthmatics. In the normal individuals, FEV1 and MMEFR increased signficantly during the postexercise period. When compared to normal subjects, the 12 asthmatic patients demonstrated a significant reduction in FEV1 an MMEFR (deltaFEV1 : 5 min, -300; 15 min, -304; o9 min, -208 ml; -18%, -17%, and -15%; deltaMMEFR: 5 min, -15; 15 min, -9; 30 min, -1L/M; -23%, -18%, and -6%) (p less than 0.01). The use of a rigidly controlled exercise stress with a cardiovascular endpoint in the measurement of FEV1 and MMEFR in the postexercise period appears to be a useful tool in assessing the presence and severity of exercise-induced bronchospasm in the adult asthmatic.

Adult↗
PubMed1976

Measurement of plasma prostaglandins during exercise-induced bronchospasm.

Bronchospasm following exercise is a phenomenon which occurs in most patients with reversible airway disease. The pathophysiologic mechanism leading to this bronchoconstriction with exercise has not yet been defined. Recently, prostaglandins have been implicated in the etiology of asthma. The purpose of this investigation was to determine changes in plasma prostaglandins occurring during exercise-induced asthma. Eight ambulant asthmatics were chosen for baseline pulmonary spirometry and peripheral venous blood prostaglandin E and F levels. The asthmatics were then exercised to 80% of their age-predicted maximal heart rate via a multistage branching treadmill protocol. At 5, 15, and 30 min following exercise, pulmonary spirometry was again performed and peripheral venous blood collected at the indicated times. Clinical bronchospasm as characterized by audible wheezing and greater than 15% decrease in FEV1 and MMEFR was obtained in all of the asthmatics. Peripheral PGE and PGF2alpha determinations following this exercise protocol were not altered significantly: (PGE: 0 min, 238; 5 min, 185; 15 min, 248; 30 min, 256 pg/ml); (PGF2alpha: 0 min, 50; 5 min, 24; 15 min, 25; 30 min, 17 pg/ml) (p less than 0.1). In summary, no significant change in peripheral blood prostaglandin E and F2alpha levels as determined by radioimmunoassay was noted at the time of exercise-induced bronchospasm.

Bronchial Spasm↗
PubMed1976

Paradoxic bronchospasm after inhalation of isoptroterenol.

Paradoxic bronchospasm induced by adrenergic aerosols, especially isoproterenol, is a well-known clinical entity. It normally occurs in patients who abuse the use of isoproterenol, but has also been reported in a small group of other patients. This study attempted to identify patients who exhibit paradoxic bronchospasm after administration of aerosolized isoproterenol. Forty-one stable, ambulant asthmatics, whose FEV 1.0 was less than 70 percent of predicted normal were studied. None of the asthmatics had taken isoproterenol for one year prior to evaluation. Baseline pulmonary function tests (FVC,FEV 1.09 MMEFR), blood pressure and ECG rhythm strips were recorded, and repeated at 15, 30, 60 and 120 min after administration of isoproterenol. Twenty-nine of the asthmatic patients had the expected normal response ( delta FEV 1.09 15 min: + 579; 30 min: + 464; 60 min: + 372; 120 min: + 307 ml: + 44, + 36, + 23 and + 24 percent) (delta MMEFR, 15 min: + 37; 60 min: + 29; 120 min: + 18L/Min: + 75, + 69, + 47 and + 37 percent). Twelve asthmatic patients (29 percent) had paradoxic bronchospasm (delta FEV 1.09 15 min: - 38; 30 min: - 60; 60 min: - 175; 120 min: - 27 ml; -1, -4, - 10 and - 4 percent) (delta MMEFR - 15 min: - .5; 30 min: - 3; 60 min: - 9; 120 min: - 2L/min; + 4, - 3, - 6 and - 5 percent, P less than 0.001).

Adult↗
PubMed1976

The adjustment of reaching behavior to object distance in early infancy.

The prehensile activity and looking behavior of 2- and 5-month-old infants were videotaped in the presence of objects placed within and beyond possible contact distance. There was only a consistent adjustment of reaching behavior to stimulus distance in the case of the 5-month-old group. The distance discrimination evident in the prehensile activity of the older infants was paralleled by a reduction in the amount of attention paid to far objects.

Attention↗