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Biomedical subjects

E Greene

Publications and source records attributed to E Greene.

At least 19 recordsLinked to original sources
PubMed1992

Control of interocular suppression as a function of differential image blur.

This experiment studied normal adults, normal children, and corrected strabismics with alternating fixation, evaluating their ability to detect information presented to one eye under viewing conditions which might affect their eye preference. An apparatus was used which allowed unconstrained, binocular viewing of a video monitor, but in which the image seen by one eye was blurred while that seen by the other eye was in sharp focus. Under these viewing conditions, subjects were asked to identify a sharply focused letter which was shown briefly to the eye which was seeing the blurred background image or to the one which was watching the well-focused image. The question was whether there would be general suppression of the eye that was shown a degraded background, causing a reduction in its ability to process other information being presented. The results indicate no performance penalty for children, a mild decrement in recognition accuracy for normal adults, and a severe deficit in the ability of corrected strabismics to attend to the eye which views a blurred image. These results suggest that the loss of binocular vision that accompanies childhood strabismus is not a result of an inherent sensitivity to blurring, insofar as such vulnerability is reflected by these acute testing conditions.

Adolescent↗
PubMed1991

Juror and expert conceptions of battered women.

The admissibility of expert testimony at the trial of a battered woman defendant is very controversial. Some courts allow the testimony, others do not. This study focuses on two criteria judges use to determine admissibility and attempts to provide an empirical foundation that can assist their decisions. First, the area of study about which an expert testifies must be shown to be reliable and valid. Second, the subject matter of the testimony must be beyond the ken of the average juror. The first criterion was addressed by assessing the opinions of 45 researchers in the field of spousal violence. The second criterion was examined by evaluating the knowledge of 141 jurors about myths and empirical research findings associated with battered women. Results indicate that researchers showed strong consensus on 14 of 18 issues included in a survey about the reactions of abuse victims, and that compared to these "experts," jurors have limited knowledge on these issues. These results suggest that many of the scientific findings concerning battered women are reliable and that the information is often beyond the ken of the jury. The findings argue for the use of expert testimony in certain cases involving battered women defendants.

Attitude of Health Personnel↗
PubMed1990

How judges sentence DUI offenders: an experimental study.

This study examined the impact of 1) a DUI offender's blood alcohol level at the time of arrest and 2) the number of prior drunken driving convictions on judges' sentencing patterns. These variables were manipulated using vignettes that were presented to all judges who sentence drunken drivers in Colorado. Judges were asked to determine appropriate amounts of jail time, fines, public service hours, and alcohol education course work. Results indicated that they gave more severe sentences to offenders with prior records and to those with higher blood alcohol levels. The effects were generally stronger for the first variable, prior record. These findings suggest that judges may perceive of and sentence repeat offenders differently than first-time offenders, regardless of the level of intoxication at arrest.

Accidents, Traffic↗
PubMed1990

Use of segment arrays to evaluate the strength of angular induction.

The contribution of local and global influence on angular induction was evaluated by varying the orientation of individual segments that were organized into an array. It was found that some of the misprojection of an oblique is determined by the orientation of the individual segments, and some by the overall configuration of the segments into two parallel bands. These results are integrated into a model that views angular induction as a lateral bias among orientation-sensitive neurons, with global influence differing from local influence only as a matter of scale.

Adult↗
PubMed1989

Angular induction as a function of contact and target orientation.

The Poggendorff effect is seen as misalignment of two obliques, or misprojection of one, when the obliques are placed outside a set of parallel lines. To understand better the mechanisms behind this effect, the orientation of the lines which are normally parallel was systematically manipulated. The results indicate that projection bias is affected by the orientation of either line, is at a minimum where the line is orthogonal to the oblique, and is maximal at small angles. This is in line with classic theories which attribute the illusion to misperception of angular size. However, such explanations presuppose that in order to be effective the induction line must be proximal to the oblique so that an angle can be formed. Results are reported which show that the angle formed by the oblique and a line placed at a distance from the oblique, serving as the target of the projection, follows an angular rule of effectiveness similar to what is seen when the line is placed directly in contact with the oblique. The underlying process is described as 'angular induction'.

Adult↗
PubMed1989

Tolerance to low-dose endotoxin in awake sheep.

Dose response and tolerance to a small intravenous dose of Serratia marcescens lipopolysaccharide (LPS) were studied in awake sheep. Core temperature significantly increased after a dose of 0.002 micrograms/kg; changes in pulmonary arterial pressure, pulmonary vascular resistance, plasma thromboxane B2, and circulating leukocyte concentration occurred after 0.02 micrograms/kg; plasma 6-keto-prostaglandin F1 alpha increased after 0.2 micrograms/kg. Development of acute tolerance was studied by injection of S. marcescens LPS (0.02 micrograms/kg iv) on 3 consecutive days: pulmonary arterial pressure and thromboxane B2 levels were significantly lower than controls after the second dose, whereas fever and the degree of leukopenia were not diminished until the third dose. After intravenous administration of LPS given in increasing doses from 0.1 to 3.2 micrograms/kg three times weekly over 7 wk, there were no measurable changes in any of the above parameters after challenge with S. marcescens LPS (0.02 micrograms/kg) after a 1-wk rest period. In awake sheep, small intravenous doses of LPS can cause physiologically important changes of the pulmonary circulation and can alter the hemodynamic and eicosanoid mediator responses to subsequent challenges with LPS. Large intravenous doses of LPS can ablate the physiological responses to subsequent small doses of LPS.

Animals↗
PubMed1989

Nafamstat mesilate attenuates pulmonary hypertension in heparin-protamine reactions.

Rapid protamine reversal of heparin anticoagulation in awake sheep caused, after 1 min, a approximately 15-fold increase of arterial plasma thromboxane B2 (TxB2) levels, a 4-fold rise of pulmonary vascular resistance (PVR), a 2-fold rise of pulmonary arterial pressure, and after 3 min, a 2-fold rise of ovine arterial plasma complement C3a levels (P less than 0.05). Infusion of nafamstat mesilate (FUT-175), a protease and complement pathway inhibitor, before protamine reduced these increases by approximately 60-90% (P less than 0.05). FUT-175 did not modify heparin + protamine-induced leukopenia, suggesting that FUT-175 incompletely blocked C5a production. We also learned that infusing protamine first and heparin 5 min later did not increase either plasma C3a or TxB2 levels or PVR while the activated clotting time increased only minimally. Thus, in awake sheep, the sequence of heparin and protamine infusion influences complement activation and pulmonary vasoconstriction. FUT-175 pretreatment reduces thromboxane release and pulmonary vasoconstriction probably by limiting complement activation.

Animals↗
PubMed1989

Effects of recombinant human tumor necrosis factor alpha, lymphotoxin, and Escherichia coli lipopolysaccharide on hemodynamics, lung microvascular permeability, and eicosanoid synthesis in anesthetized sheep.

We infused recombinant human tumor necrosis factor alpha (rhTNF alpha), lymphotoxin (rhLT), and Escherichia coli 0111:B4 lipopolysaccharide (LPS) into anesthetized sheep with a lung lymph fistula to compare their effects on systemic and pulmonary hemodynamics, lung lymph dynamics, and eicosanoid release. rhTNF alpha (25-150 micrograms/kg, n = 6 sheep), but not rhLT (25 micrograms/kg, n = 3), rapidly increased lung lymph and plasma levels of 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha) and caused profound systemic vasodilation and hypotension. Meclofenamate pretreatment (10 mg/kg) of three other sheep given 25 micrograms/kg rhTNF alpha prevented the increase of lymph and plasma 6-k-PGF1 alpha levels, systemic vasodilation, and the early (less than 2 hrs) but not the late (4-6 hours) hypotension caused by rhTNF alpha. LPS (1 micrograms/kg, n = 11) induced a briefer increase of lymph 6-k-PGF1 alpha levels than did rhTNF alpha while plasma 6-k-PGF1 alpha levels did not increase. LPS induced more gradual hypotension than did rhTNF alpha but did not cause systemic vasodilation. LPS and rhTNF alpha, but not rhLT, increased lymph thromboxane B2 (TXB2) levels during the first hour of study, whereas only LPS acutely increased plasma TXB2 levels. LPS caused acute pulmonary vasoconstriction and greater acute pulmonary artery hypertension than did either rhTNF alpha or rhLT. Whereas LPS-treated sheep required less fluid transfusion than rhTNF alpha-treated sheep to maintain mean systemic arterial pressure greater than 50 mm Hg, LPS infusion caused a greater increase of lung lymph protein clearance. rhTNF alpha caused minimal alterations of lung microvascular permeability. We conclude that eicosanoid mediators contribute importantly to differences of systemic and pulmonary hemodynamics caused by these agents in sheep. rhTNF alpha cannot account for all of the LPS-induced hemodynamic, lung lymph, and eicosanoid responses in sheep.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

The effect of stroke on object recognition.

Stroke patients were tested for their ability to recognize familiar objects shown in photographs, and we have confirmed previous reports that damage to the right hemisphere impairs recognition of objects shown at an "unusual angle". Additionally, these patients were impaired in matching unfamiliar (nonsense) objects which had been rotated. These impairments are discussed in the context of key task demands, particularly the need to extract depth cues from the photographs, and to rotate form elements to determine whether the samples provided different views of the same object. In the context of other work, these results suggest impairment of advanced perceptual skills which are needed to establish relationships of and among features of the forms.

Adult↗
PubMed1988

The corner Poggendorff.

With the classic Poggendorff illusion a set of parallel 'induction lines' will cause a set of oblique line segments to look misaligned even though they are collinear. A different kind of misalignment can be produced by placing the induction lines so that they form a corner. Under these conditions the obliques will appear to be angled slightly, one relative to the other. The effects are small, but can be seen and reliably reported by a group of naive subjects. The influence of the induction lines drops sharply as their relative position is moved from parallel to orthogonal, but there is a small residual influence which may be called the corner Poggendorff effect.

Attention↗
PubMed1987

The relative contribution of contact and target lines in the magnitude of the Poggendorff effect.

It is well known that a set of parallel lines can cause misperception of the projected path of an oblique. Most studies of this effect have emphasized either the proximal or the distal stimulus components--the line with which the oblique makes contact, or the line that serves as the target of the projection. An experiment is reported in which the relative contribution of the contact and target lines was examined. The results indicate that rotation of either line can determine the magnitude of the projection error.

Attention↗
PubMed1986

Thalamic role in spatial memory.

The contribution of structures in the limbic diencephalon to spatial memory function was investigated. Rats with lesions of either the anteroventral thalamus, anteromedial thalamus, dorsomedial thalamus or mammillary bodies were compared in their ability to perform a delayed alternation task. The results indicate the ablation of the thalamic nuclei did not impair delayed-alternation memory, but there was impairment following damage to the mammillary bodies. Placement of the discrete lesions was verified using Nissl sections and by tracing the pattern of projections using a silver degeneration stain. The results suggest that individual thalamic nuclei are not essential in the storage and/or retrieval of spatial memory. The data are discussed in terms of spatial deficits resulting from damage to the hippocampus proper or to the pathways connecting it to other brain structures.

Animals↗
PubMed1986

Selective culture medium enhances survival of neuroblasts from postnatal rodent brain.

One of the major limitations to the study of the development of the nervous system in aneuploid mammalian embryos is that the aneuploid condition is usually lethal in utero. Liveborn aneuploid individuals often succumb rapidly because they have a constellation of malformations incompatible with postnatal survival. We have developed a selective tissue culture medium (D-val) which can be used with fetal calf serum or in a serum-free defined composition and which permits neuroblasts and glioblasts present in postnatal rodent (rat, mouse) brain to proliferate and differentiate in vitro. These cells contain D-amino acid oxidase, but fibroblasts do not. In this medium, fibroblasts cannot grow and are eliminated from the cultures without the use of deleterious compounds such as antimitotic or chemotherapeutic agents. With this medium, cultures containing neuroblasts can be established from normal rat and mouse brain as late as postnatal days 11-20. Cultures with significant numbers of proliferating cells can also be established from perinatal aneuploid mouse embryos, 'rescuing' the cells for further study.

Animals↗
PubMed1986

Urine C-peptide and creatinine (Jaffe method) excretion in healthy young adults on varied diets: sustained effects of varied carbohydrate, protein, and meat content.

We studied effects of isocaloric diets of varied composition (each diet offered for 5 to 7 days) on urine C-peptide and creatinine excretion in eight healthy subjects. C-peptide excretion was higher on the high carbohydrate (60% CHO, 20% PRO) and high protein (45% CHO, 30% PRO) diets than on the low carbohydrate (30% CHO, 20% PRO) and low protein diets (45% CHO, 10% PRO). C-peptide excretion correlated with total kilocalories ingested (r = 0.594, p less than 0.001), and also with CHO (r = 0.469, p = 0.003) and PRO intake (r = 0.453, p = 0.004). Multiple regression analysis is given by the formula: Urine C-peptide (nmol/24 h) = 17.3 + 0.01 (kcal/24 h) + 0.021 (gm CHO/24 h) + 0.049 (gm PRO/24 h) Creatinine excretion was related to body weight (r = 0.959, p less than 0.001) and also to total PRO intake (r = 0.569, p less than 0.001) and meat intake (r = 0.367, p less than 0.05). We conclude that diet composition, especially protein intake, is an important stimulus to sustained insulin production as measured by C-peptide in healthy subjects. Diet composition has a significant impact on creatinine excretion. Urine creatinine cannot be assumed to reflect only lean body weight when it is used as a measure of the adequacy of timed urine collections.

Adult↗
PubMed1979

The influence of stroke on visual illusion magnitude.

In an attempt to resolve contradictory reports about the effect of right-versus left-hemisphere damage on perception of the Mueller-Lyer illusion, the present study examined judgments of stroke patients using this and several other visual illusions. The results provide some indication of abnormal perception of the Mueller-Lyer by patients with left-hemisphere damage. But the overall magnitude of illusion was normal in both groups of patients. It is possible that stroke damage did not affect the brain areas that are responsible for "gestalt" synthesis. However other recent studies using the Mueller-Lyer suggest that actual or incipient eye movements play an important role in the perception of this illusion, and under some conditions of testing, it is the activity of the left hemisphere that determines illusion magnitude.

Brain Mapping↗
PubMed1977

Syndrome of acquired factor X deficiency and systemic amyloidosis; in vivo studies of the metabolic fate of factor X.

To determine the metabolic fate of factor X in primary amyloidosis associated with factor X deficiency, we examined the pathways of its catabolism in a man with this syndrome. Intravenous infusion of human or bovine 131I-labeled factor X established a triphasic plasma clearance pattern for factor X. About 85 per cent of the factor X disappeared, with a disappearance half-time of less than 30 seconds. A second and third phase showed a T1/2 of 90 minutes and nine hours respectively. 131I-labeles factor X in plasma did not appear to be rapidly modified or degraded. Relatively minor quantities of 131I were cleared into the urine. We observed a diffuse distribution of radioactivity over the body surface, with a concentration in the hepatic and splenic regions. These studies demonstrate than factor X deficiency associated with systemic amyloidosis is due to binding of factor X to body tissue, probably within the circulatory system.

Amyloidosis↗