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Biomedical subjects

M E Mercer

Publications and source records attributed to M E Mercer.

13 recordsLinked to original sources
PubMed1997

Food cravings, endogenous opioid peptides, and food intake: a review.

Extensive research indicates a strong relationship between endogenous opioid peptides (EOPs) and food intake. In the present paper, we propose that food cravings act as an intervening variable in this opioid-ingestion link. Specifically, we argue that altered EOP activity may elicit food cravings which in turn may influence food consumption. Correlational support for this opioidergic theory of food cravings is provided by examining various clinical conditions (e.g. pregnancy, menstruation, bulimia, stress, depression) which are associated with altered EOP levels, intensified food cravings, and increased food intake.

Alcoholism↗
PubMed1997

Antinociceptive effects of palatable sweet ingesta on human responsivity to pressure pain.

Palatable sweet ingestion produces a morphine-like analgesia in both rats and human infants (2-5). To determine whether palatable sweet ingesta induces antinociception in human adults, 60 university students (30 men, 30 women) were exposed to a pressure algometer both before and after consuming either a sweet soft drink, filtered tap water, or nothing (Experiment 1). Pain responsivity was assessed with four pain measures: threshold, tolerance, and visual analogue scale (VAS) ratings of intensity and unpleasantness. Results showed that women who consumed either soft drink or water reported increased pain tolerance and VAS ratings at posttreatment compared with those receiving nothing. However, differences between groups were not found for men. Moreover, compared to men, women reported lower pain thresholds and tolerances and rated the pain as more intense. In Experiment 2, 40 women consumed either nothing or foods that they rated previously as palatable (chocolate-chip cookies), unpalatable (black olives), or neutral (rice cakes). Women who consumed the palatable sweet food showed increased pain tolerance compared with those receiving the unpalatable food, the neutral food, or nothing. These data constitute the first demonstration that "palatability-induced antinociception" (PIA) can occur in human adults.

Adolescent↗
PubMed1994

Systematic measurement of human neonatal color vision.

We used a new time-efficient method to evaluate chromatic-achromatic discrimination in newborn (n = 36) and 1-month-old (n = 34) human infants. Results showed that 74% of newborns discriminated a 10.5 x 17.5 deg broadband red patch from all relative luminances of an achromatic background, but only 14% of newborns did so with a blue, 36% with a green, and 25% with a yellow patch. Most infants who "failed" did so at relative luminances very close to the respective photopic luminance match. At 1 month, performance improved somewhat although infants still show clear evidence of discriminating only the red patch. These results, the first to be obtained from individual newborns with a method incorporating a systematic variation of luminance, imply that early color vision is very limited. Possible photoreceptoral and neural bases for these immaturities are discussed.

Child Development↗
PubMed1992

A new technique to measure contrast sensitivity in human infants.

We used a new time-efficient procedure to obtain binocular contrast sensitivity functions (CSFs) from 80 infants aged 1-, 3-, 6-, and 12-months-old. The test consisted of 5 sets of large (50 by 28 cm) cards constructed by mounting a 7.2 degrees circular sine wave grating with 1 of 5 spatial frequencies (0.3, 0.6, 1.2, 2.4, and 3.6 cpd at 60 cm) onto light gray matteboard. Each card also contained a second 7.2 degrees unpatterned patch of equal space-average luminance. Depending upon the set, the contrast within the gratings ranged from approximately 25 to 0.5%. To judge the subject's detection of each grating we used a rapid version of preferential looking (PL) similar to that developed for the Teller Acuity Cards. Results showed that compared to previous techniques, the card procedure allows one to estimate an infant's CSF much more simply, rapidly, and inexpensively.

Contrast Sensitivity↗
PubMed1991

Deficiencies in human neonates' color vision: photoreceptoral and neural explanations.

Several photoreceptoral and neural models have been proposed to account for the development of human vision. To further evaluate those applicable to color vision, the present study examined 40 neonates' (mean age = 3.2 days) chromatic-achromatic discriminations in the mid-spectral region by using an habituation procedure and measures to minimize achromatic cues. Results indicated that newborns showed evidence of discriminating broad-band orange (lambda peak = 595 nm) but not yellow-green (lambda peak = 565 nm) lights from achromatic lights of varying luminance. Collectively, these and previous results imply that although newborns have at least dichromatic color vision, they possess relatively poor chromatic-achromatic discrimination in two spectral regions - in the short-wavelengths (including stimuli of 470-480 nm) and in the mid-wavelengths (including 565 nm). Although several hypotheses were considered, newborns' chromatic 'neutral zones' are best accounted for by models proposing that early color vision is limited by a general inefficiency of preneural (photoreceptoral and optical) mechanisms and/or by a selective immaturity of the SWS cones or the B/Y opponent channel.

Arousal↗
PubMed1991

Contrast/color card procedure: a new test of young infants' color vision.

We have developed a new test which can rapidly evaluate basic color vision in individual infants. The test consists of a series of large cards constructed with Munsell Hues. It uses a modified preferential looking procedure (FPL) and, to control brightness cues, incorporates a two-phase systematic variation of luminance. First, we evaluate an infant's ability to discriminate 9.5 by 16 degrees achromatic patches of varying luminance from a 26 by 65 degrees achromatic background of midrange luminance. In the second phase the test patch is chromatic and its luminance, relative to the background, is varied over a range of about 1.0 log cd/m2. The number of relative luminances chosen for each infant depends upon his/her performance in phase 1. Seventy 2- and 3-month-olds were tested with 4 broad-band chromatic patches, a red (dominant lambda = 660 nm), a yellow (dominant lambda = 580 nm), a green (dominant lambda = 520 nm), and a blue (dominant lambda = 475 nm). Results showed that 3-month-olds had little difficulty making any of the chromatic-achromatic discriminations but many 2-month-olds appeared to fail to discriminate the yellow and green from the background at relative luminances close to an adult brightness match. Most importantly, the test shows promise as a relatively simple, time-efficient, and portable tool for the assessment of early color vision.

Color Perception Tests↗
PubMed1989

Wavelength effects on critical flicker frequency in human infants.

We examined 3-mo.-old human infants' ability to detect flicker in 454-nm blue and 627-nm red lights at 1.5 log cd/m2. Infants showed the same critical flicker frequency (CFF) to both wavelengths, suggesting that retinal cones mediate the detection of flicker at this luminance level. Infants' CFFs for chromatic stimuli were much lower than those reported for achromatic stimuli and also much lower than adults' CFFs tested under the same conditions.

Adult↗
PubMed1988

Pharmacy-nursing discharge counseling program for cardiac patients.

A cooperative pharmacy-nursing program for discharge medication counseling for cardiac patients that uses printed medication teaching cards is described. A pharmacy-nursing working group had determined that a formal program for discharge medication counseling was needed, and a pilot program was implemented on the cardiopulmonary-care units. Medication teaching cards were developed for commonly prescribed cardiac medications. Because the cardiologists who reviewed the completed cards were worried that widespread dissemination of the cards would cause some patients to suffer undue anxiety about adverse effects, a standard order form was developed so that physicians could order specific cards for patients. Patients who receive medications included in the program are counseled by a registered nurse; pharmacists occasionally are called upon to answer specific questions or to actually provide the counseling. In the first six months of the program, 86 patients received an average of three cards each. Although no formal evaluation of the program has been performed, feed-back from patients has been favorable and plans to expand the program to include more drugs and other types of patients are in effect. A cooperative pharmacy-nursing program for discharge medication counseling using printed information has proved to be an effective and efficient way of sharing necessary drug information with patients.

Drug Information Services↗