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Biomedical subjects

R Fudin

Publications and source records attributed to R Fudin.

35 records · Page 2Linked to original sources
PubMed1991

Protamine sulfate induces enhanced peritoneal permeability to proteins.

We present a direct link between the neutralization of anionic sites by intraperitoneal protamine and a rise in protein passage to the peritoneal cavity during isosmotic peritoneal dialysis in rabbits. Each experiment included two 1-hour exchanges. No drugs were added in the first exchange. In group A (control) there were no drugs in the second hour either. In group B, protamine (50 micrograms/ml) was added to the second exchange volume. In group C, protamine and heparin (50 U/ml) were added. In groups A and C, appearance curves of metabolites during the first (baseline) and the second (experimental) hours were not statistically different. In group B, differences for urea, glucose and uric acid were not significant, but they were highly so for protein (increase of 100%, p less than 0.01). Transperitoneal passage of albumin is substantially enhanced by protamine. Neutralization of protamine with heparin prevents this, showing that availability of anionic sites is the crucial limiting factor. Protamine did not significantly affect the transfer of small neutral molecules.

Animals↗
PubMed1991

Review of auditory subliminal psychodynamic activation experiments.

Subliminal psychodynamic activation experiments using auditory stimuli have yielded only a modicum of support for the contention that such activation produces predictable behavioral changes. Problems in many auditory subliminal psychodynamic activation experiments indicate that those predictions have not been tested adequately. The auditory mode of presentation, however, has several methodological advantages over the visual one, the method used in the vast majority of subliminal psychodynamic activation experiments. Consequently, it should be considered in subsequent research in this area.

Aggression↗
PubMed1990

Anionic fixed charges in the fenestrated capillaries of the mouse mesentery.

Previous studies showed the existence of submesothelial fenestrated capillaries in the human parietal and rabbit diaphragmatic peritoneum, as well as in the mouse mesentery. The present study demonstrates the presence of electronegative fixed charges at the luminal aspect of endothelial cells, as well as long the subendothelial basement membrane of the fenestrated capillaries of the mouse mesentery. This situation will eventually preclude the transfenestral passage of anionic plasma proteins. On the other hand, fenestrated capillaries are much more permeable to water and small-molecular-size solutes than those of the continuous type. Therefore, the high hydraulic conductivity of fenestrae may well imply that a substantial part of water and small solutes leave the blood compartment through the fenestral channels.

Animals↗
PubMed1989

Reading efficiency and the development of left-to-right writing by the ancient Greeks.

Ancient Greeks added vowels to a consonantal language and changed their horizontal writing direction from right-to-left to left-to-right. The idea that the dextral majority in ancient Greece developed left-to-right writing solely because writing efficiency was greater is questioned. Cerebral hemispheric functions that might be involved during fixation pauses in reading suggest that horizontal ancient Greek was read more efficiently from left to right than from right to left, the other direction in which it usually was written. The same considerations suggest that horizontal consonantal scripts are read more efficiently from right to left than from left to right. The importance of boustrophedon, a continuous writing style, in the development of left-to-right writing and aspects of the reciprocity between cerebral hemispheric functioning and writing direction of vocalic scripts are discussed.

Functional Laterality↗
PubMed1988

Can caffeine antagonize alcohol-induced performance decrements in humans?

Design aspects and results of experiments that investigated the effects of caffeine on alcohol-induced performance decrements in humans are discussed. Simple conclusions concerning those outcomes are unwarranted because they seem to depend on the tasks used and the dosages of both drugs, with both antagonism and potentiation of alcohol-induced effects having been reported. Results indicate that legally intoxicated individuals cannot antagonize alcohol-induced, driving-related decrements with caffeine prior to driving an automobile, thought to be the major behavior for which caffeine is used in attempts to antagonize alcohol-induced decrements. We offer suggestions for research concerning subjects' habitual use or nonuse of caffeine and typical alcohol consumption levels, the interval between alcohol and caffeine ingestion, and the effects of caffeine and alcohol alone on performance tasks. We also suggest that statistical analyses should allow for a differentiation of results in which caffeine partially offsets an alcohol-induced decrement from more positive results in which caffeine returns functioning to its normal level.

Automobile Driving↗
PubMed1982

Note on criteria for writing posture used to test Levy and Reid's cerebral organization hypotheses.

Apparent ambiguities in Levy and Reid's writing posture criteria and dissimilar criteria used by other investigators are discussed. Classification of inverted writing postures by a diagram which, as Levy and Reid indicated in 1976, depicts typical writing positions is questioned because their 1978 paper suggests that these diagrammed positions were only an intermediary stage in the classification of some inverters. Results of studies using dissimilar criteria for writing posture appear to be difficult to compare because subjects who may differ in cerebral organization might be placed in the same category. Some of these studies introduced another possible source of confounding because different tasks were used to test lateralization of function. Since different tasks seem to study distinctive facets of language, lateralization of one function in sinistrals, thought to be less lateralized than dextrals, does not predict lateralization of any other function. These considerations suggest that an adequate test of Levy and Reid's ideas concerning the relationship among handedness, hand posture during writing, sex, and cerebral organization requires the development of a standard set of valid criteria for writing posture.

Dominance, Cerebral↗
PubMed1976

Note on duration of stimulus exposure in experiments on covert scanning of laterally shown targets.

Prevention of contamination by eye movements is on methodological requirement in the choice of an exposure time in experiments on the covert scanning of stimuli, tachistoscopically exposed laterally. The use of measures of eye movement latency to set upper limits for exposure intervals seems questionable because latency does not index the total time (minimally, 200 msec.) required to obtain information through an eye movement. The foregoing requirement, however, is only one consideration in selection of an exposure time. Since covert encoding processes can only function while the stimulus is on and during the after-stimulation, duration of exposure delimits the operating time of these processes. Choice of an interval, therefore, should establish the setting required to study those aspects of covert scanning of experimental interest.

Attention↗
PubMed1976

Integration of post-exposural directional scanning and cerebral dominance explanations of lateral differences in trachistoscopic recognition.

Post-exposural directional scanning and cerebral dominance are major postualtes which account for lateral differences in tachistoscopic perception. These ideas can be intergrated when tachistoscopic perception is viewed as a short-term memory task. Briefly exposed stimuli not only have to be scanned, but also rehearsed, subvocally, before they can be encoded. Since most Ss are left-hemisphere dominant for language, scanned information arriving in the right hemisphere has to be sent to the left hemisphere for rehearsal. This transmission effects a loss of scanned information because it is held in a rapidly dissipating storage. These ideas account for lateral differences found with vertically and horizontally oriented targets, but methodological considerations are discussed which indicate that these notions are more clearly demonstrable with the former than latter displays .

Dominance, Cerebral↗
PubMed1976

Analysis of superiority of the right visual field in bilateral tachistoscopic word-recognition.

McKeever and Huling questioned procedures in experiments on lateral differences in the recognition of horizontally oriented multi-letter stimuli, tachistoscopically exposed bilaterally. They effected three major changes in this method and found superior scores for material in the right than left visual field, a result in the opposite direction of prior findings. Ideas from directional scanning and cerebral dominance accounts of lateral asymmetries suggest that McKeever and Huling's methodological innovations produced their result. Directional scanning notions indicate that horizontal targets impede measures of differences in processing skills of the cerebral hemispheres. These obstacles can be overcome by exposing vertically oriented targets.

Dominance, Cerebral↗
PubMed1975

Perception of geometrical arrays tachistoscopically exposed in right and left visual fields.

Geometrical stimuli (48 6-item arrays of familiar forms, e.g., circle), tachistoscopically presented in the right or left visual field, were more accurately perceived in the right than left visual field by 15 college students. Targets about half the length of the displays exposed here were perceived with equal facility in both visual fields (Bryden, 1960). Results suggest that length of array might affect the difference in perceptual accuracy of forms shown in the right and left visual fields. Figures in the right visual field were predominantly processed from left to right, and forms in the left visual field from right to left. Since more symbols were identified in the right than left visual field, the left to right encoding sequence may be more efficient than a right to left movement. Limited experience of most Ss in reading symbols from left to right is probably only one factor. Extensive experience reading alphabetical material from left to right might have developed the physiological mechanism underpinning this sequence more than the one serving the opposite movement.

Adolescent↗
PubMed1975

Identification of tachistoscopically exposed symmetrical and asymmetrical letter arrays.

Six-letter arrays containing symmetrical, e.g., H, M, T, or asymmetrical letters, e.g., J, K, R, were tachistoscopically exposed bilaterally for 100 msec. to 100 college students. Significantly more asymmetrical than symmetrical letters were identified, and significantly more Ss identified more asymmetrical than symmetrical items. This experiment, which incorporated methodological considerations suggested by Harcum (1964) and Bryden (1968), corroborates their findings. Their ideas and other findings were used to account for the data. Asymmetrical letters have more intrinsic left-to-right directionality than symmetrical elements. The rapidly fading after-stimulation of tachistoscopically presented alphabetical material is usually scanned from left to right. Individual array letters might also be scanned in the same direction. Confluence of directionality of letter and scan, which obtains only with asymmetrical letters, might have typically allowed asymmetrical targets to be scanned more rapidly and, consequently, more efficiently than symmetrical displays.

Afterimage↗