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Biomedical subjects

L Payne

Publications and source records attributed to L Payne.

14 recordsLinked to original sources
PubMed1992

Antiserum to prolactin decreases rapid eye movement sleep (REM sleep) in the male rat.

Previous reports suggest that blood-born prolactin (PRL) may selectively promote rapid eye movement sleep (REMS). To study the possible involvement of endogenous PRL in sleep regulation, rats were systemically injected with either antiserum to PRL or normal rabbit serum, and the sleep-wake activity was determined during the subsequent 12-h light cycle. The administration of normal rabbit serum in physiological saline did not alter sleep-wake activity compared to control recordings, whereas the PRL antiserum caused a modest and selective suppression in REMS. Immunoreactive PRL was eliminated from the serial plasma samples obtained between 6 to 11 h after the injection of the antiserum. Brain temperature was not affected by the antiserum. The results indicate that physiological pituitary PRL secretion has a slight REMS-promoting activity in the male rat. It is speculated that an increased release of pituitary PRL or the PRL-like substance previously demonstrated in the brain may significantly stimulate REMS.

Animals↗
PubMed1992

Growth hormone-releasing hormone antibodies suppress sleep and prevent enhancement of sleep after sleep deprivation.

Previous reports suggest that the hypothalamic growth hormone-releasing hormone (GHRH) promotes sleep, especially non-rapid-eye-movement sleep (NREMS). To evaluate the role of endogenous GHRH in sleep regulation, the effects of antibodies to rat GHRH (GHRH-ab) were studied on normal sleep, brain temperature (Tbr), and GH secretion in experiment I and on enhanced sleep after sleep deprivation in experiment II. In experiment I, affinity-purified GHRH-ab (50 and 200 micrograms) raised in goats and a control goat immunoglobulin G (IgG) preparation were injected intracerebroventricularly (icv) in rats 1 h before the onset of the light cycle, and sleep-wake activity and Tbr were recorded for the next 12 or 23 h. Both doses of GHRH-ab suppressed NREMS and REMS throughout the light cycle. Sleep durations at night were normal. Electroencephalographic (EEG) slow-wave activity, characterized by EEG slow-wave amplitudes, was reduced after GHRH-ab during both the light and the dark cycles. Plasma GH concentrations measured 6-12 h after injection of GHRH-ab (200 micrograms) were diminished. Both the control IgG and GHRH-ab elicited fever. In experiment II, the sleep-wake activity and Tbr of rats were recorded for 24 h in three experimental conditions: base-line with icv injection of IgG, 3-h sleep deprivation with icv IgG injection, and 3-h sleep deprivation with icv GHRH-ab (200 micrograms). After sleep deprivation (+IgG), a prompt increase in EEG slow-wave activity (power density analysis) and late increases in NREMS and REMS durations were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Inhibition of growth hormone-releasing factor suppresses both sleep and growth hormone secretion in the rat.

To study the possible involvement of hypothalamic growth hormone-releasing factor (GRF) in sleep regulation, a competitive GRF-antagonist, the peptide (N-Ac-Tyr1,D-Arg2)-GRF(1-29)-NH2, was intracerebroventricularly injected into rats (0.003, 0.3, and 14 nmol), and the EEG and brain temperature were recorded for 12 h during the light cycle of the day. Growth hormone (GH) concentrations were determined from plasma samples taken at 20-min intervals for 3 h after 14 nmol GRF-antagonist. The onset of non-rapid eye movement sleep (NREMS) was delayed in response to 0.3 and 14 nmol GRF-antagonist, the duration of NREMS was decreased for one or more hours and after 14 nmol EEG slow wave amplitudes were decreased during NREMS in postinjection hour 1. The high dose of GRF-antagonist also suppressed REMS for 4 h, inhibited GH secretion, and elicited a slight biphasic variation in brain temperature. These findings, together with previous observations indicating a sleep-promoting effect for GRF, support the hypothesis that hypothalamic GRF is involved in sleep regulation and might be responsible for the correlation between NREMS and GH secretion reported in various species.

Animals↗
PubMed1991

1-(substituted)benzyl-5-aminoimidazole-4-carboxamides are potent orally active inhibitors of Trypanosoma cruzi in mice.

1-(Substituted)benzyl-5-aminoimidazole-4-carboxamides are potent orally active inhibitors of Trypanosoma cruzi infections in mice. The most active compounds are the 1-(4-chlorobenzyl)- and 1-(3,4-dichlorobenzyl)-analogs (L-153,094 [2] and L-153,153 [4], resp.) which are approximately 7-fold more potent upon oral administration than nifurtimox (Lampit) in suppressing parasite levels in the blood of mice with acute Trypanosoma cruzi infections.

Aminoimidazole Carboxamide↗
PubMed1991

Sleep in diabetic rats: effects of interleukin 1.

Previous observations indicate that both interleukin 1 beta (IL-1 beta) and insulin are involved in sleep regulation. IL-1 beta has been reported to stimulate insulin secretion, suggesting that some of the effects of IL-1 beta are mediated by insulin. The purpose of the current experiments was to study the possible role of endogenous insulin in physiological sleep regulation and in the hypnogenic effects of exogenously administered IL-1 beta. Isotonic saline or IL-1 beta (2.5 ng) was intracerebroventricularly injected into normal and streptozocin-diabetic rats at dark onset, and sleep-wake activity and brain temperature were recorded for 24 h. Blood samples were collected every 20 min during the first hour postinjection for plasma insulin measurement. In diabetic rats, rapid-eye-movement (REM) and non-REM sleep were significantly decreased during the second part of the light period on the baseline day. IL-1 beta elicited a biphasic sleep response in both normal and diabetic rats. This initial increase in non-REM sleep during the first 4 h postinjection was followed by significant sleep suppression in both groups. Brain temperature was not affected in either group. Plasma insulin concentration decreased in response to IL-1 beta in normal rats, whereas insulin was below the level of detection in the diabetic rats. These results indicate that, although sleep is disturbed in diabetic rats, pancreatic insulin might not have a decisive role in the regulation of sleep in rats, and it does not mediate the effects of IL-1 beta on sleep-wake activity.

Animals↗
PubMed1990

Responsiveness of rats to interleukin-1: effects of monosodium glutamate treatment of neonates.

Monosodium glutamate (MSG) treatment of neonatal rats results in degenerative lesions of the medial basal hypothalamus, particularly the arcuate nucleus (AN). The AN is rich in corticotropin-releasing hormone (CRF) and adrenocorticotrophic hormone/alpha-melanocyte-stimulating hormone (alpha-MSH). These substances are part of a negative feedback mechanism for the regulation of interleukin-1 (IL1), a cytokine with diverse biologic actions including a role in sleep regulation. The purpose of these experiments was to determine the effects of exposure of neonatal rats to MSG on their responsiveness as adults to IL1. Adult rats, treated as neonates with MSG or the saline, were injected intracerebroventricularly during the light phase with three doses of IL1 (2.5, 10.0, 25.0 ng) and sleep-wake activity determined and brain temperature recorded for the next 6 hr. IL1 administration induced fever in both treatment groups at each dose of IL1 tested, and the febrile response of the MSG rats to the 25.0 ng dose of IL1 was greater than that of the saline control rats. In saline-treated rats, the 2.5 ng dose of IL1 enhanced non-rapid-eye-movement sleep (NREMS) without affecting rapid-eye-movement sleep (REMS) or wakefulness, whereas the 25.0 ng dose of IL1 inhibited both NREMS and REMS. In contrast, only the 10.0 ng dose of IL1 altered NREMS in MSG-treated rats. These results support the hypothesis that CRF- and alpha-MSH-containing perikarya are involved in regulation of IL1 actions.

Adrenocorticotropic Hormone↗
PubMed1990

Acute hypotensive responses to peptide inhibitors of renin in conscious monkeys: an effect on blood pressure independent of plasma renin inhibition.

In order to investigate the hypotensive mechanisms of action of peptide renin inhibitors, blood pressure responses to five renin inhibitors were compared with those to the angiotensin converting enzyme inhibitor, enalaprilat, in conscious African green and rhesus monkeys. (3S-4S)-4-amino-5-cyclohexyl-3-hydroxy pentanoic acid (ACHPA)-containing renin inhibitory peptide (ACRIP) and enalaprilat both decreased blood pressure in euvolemic and volume-depleted African green monkeys. However, while a maximum dose of enalaprilat reduced blood pressure to 80 +/- 4 and 56 +/- 4 mmHg in the euvolemic and volume-depleted monkeys, respectively, ACRIP lowered pressure to life-threatening levels (less than 40 mmHg) under both conditions. The relative potencies of ACRIP and four other renin inhibitors for inhibiting in vitro plasma renin activity (PRA; IC50) were compared with their potencies in reducing blood pressure by 15 mmHg (ED15 mmHg) and lowering blood pressure more than enalaprilat in volume-depleted rhesus monkeys. All renin inhibitors lowered blood pressure significantly beyond the maximal response to enalaprilat. Despite a significant correlation (r = 0.99, P less than 0.05) between the in vitro PRA inhibitory potency and the in vivo ED15 mmHg, doses which lowered blood pressure beyond the maximal responses to enalaprilat were not significantly correlated (r = 0.53, P greater than 0.05) with the in vitro PRA IC50 values. Furthermore, the profound depressor responses to renin inhibitors in rhesus monkeys were accompanied by increases in the heart rate and decreases in pulse pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Hypertonic saline resuscitation in a porcine model of severe hemorrhagic shock.

The purpose of this study was to investigate the effect of 7.5% hypertonic saline solution (HTS) as the initial solution in resuscitation of a pig in shock. Twenty-two animals were bled 50% of their blood volume over 30 minutes and maintained in shock for 60 minutes. The 14 survivors were divided into two groups. The first group was given 20 mL/kg of lactated Ringer's solution (LR) over a ten-minute period, while the second group was given 10 mL/kg of HTS. Both groups were then given LR at 2 mL/kg/min until the mean arterial pressure reached 80 mm Hg. The HTS group achieved a more rapid rise in mean arterial pressure over the first ten minutes of resuscitation. During this period, the cardiac index increased significantly more in the HTS group when compared with the LR group. All animals in the HTS group developed an adequate urine output. Only two animals in the LR group developed an adequate urine output. Hypertonic saline solution markedly improved survival, and there were significant improvements in hemodynamics. This was accomplished with smaller volumes of resuscitation fluid and may prove useful under conditions where intravascular access is limited.

Animals↗
PubMed1988

It's magic!

Explore the source record for details and available documents.

History, 15th Century↗
PubMed1987

Computer-managed instruction: an alternative teaching strategy.

Computer-managed instruction is an instructional strategy whereby the computer is used to provide learning objectives, learning resources, and assessment of learner performance. Computer-managed instruction (CMI) aids the instructor in instructional management without actually doing the teaching. Central CMI themes discussed in the literature are individualization, behavioral objectives, and educational technology. The main objective of this study was to compare the outcomes of two teaching strategies: CMI versus the traditional lecture method. The learning objectives were based on specified theoretical content from a Health Assessment course for baccalaureate nursing students. The design of the study was quasi-experimental incorporating two experimental treatments applied to two groups on two occasions. Data analysis addresses differences between groups using CMI and the traditional lecture method. The variables examined were the cognitive performance of learners, the learner's attitude toward the instructional strategy, the learner's retention of knowledge, the time involved in mastering the learning objectives, and the relationship between learner characteristics and the effectiveness of the instructional strategy. No significant mean difference (p less than 0.05) was found between groups on cognitive performance as measured by written and practical examination scores. For these first-year baccalaureate nursing students, CMI did not prove to be a positive instructional method as assessed by the Attitude Questionnaire. The majority of students preferred a combination of instructional methods. There was no significant difference between groups in the time spent meeting the learning objectives by either teaching strategy. The findings suggested that these students preferred learning strategies that are traditional in nature and teacher directed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1978

Polypeptide composition of extracellular enveloped vaccinia virus.

Extracellular enveloped vaccinia (EEV) virus grown in SIRC and in HeLa cells was purified by consecutive equilibrium centrifugations in sucrose and cesium chloride gradients. A higher degree of purity was obtained with virus material prepared in SIRC cells. The polypeptides of purified EEV and INV (intracellular naked vaccinia) virus were compared in polyacrylamide slab gel electrophoresis. Three proteins (200,000 molecular weight [200K], 95K, and 13K) detected in HeLa-derived INV were absent in EEV. In addition, two INV proteins (65K and 30K) occurred in reduced concentrations in EEV, white another INV protein (27K) was increased in EEV. INV from SIRC cells showed similar alterations of these proteins (with the exception of the 30K and 13K proteins). Detergent treatment, ether extraction, and Pronase treatment showed that these six proteins are located at the surface of INV and are not cecessary for infectivity. Eight proteins (210K, 110K, 89K, 42K, 37K, 21.5K, 21K, and 20K) were detected in EEV that were absent from inv. Brij-58 treatment was employed to remove the envelope from EEV, resulting in the formation of naked particles and an envelope fraction which were separated on cesium chloride gradients. The envelope fractions contained all eight proteins. Seven of the eight proteins were glycoproteins, with the 37K protein being the only unglycosylated protein. It is concluded that a processing of surface INV particle proteins occurs during evelopment. The resultant EEV particle is comprised of an INV particle with a modified surface composition enclosed in an envelope containing virus-specific proteins unique to EEV.

Cell Line↗
PubMed1977

Single radial immunodiffusion test for detecting antibodies against surface antigens of intracellular and extracellular vaccinia virus.

Antibodies to surface antigens of intracellular naked vaccinia virus (INV) and in limited studies extracellular enveloped virus (EEV) were determined by single radial immunodiffusion tests (SRDT) with immobilized virions in agarose gels. Antibodies to INV were demonstrable in rabbit hyperimmune sera (one to four visible zones), smallpox convalescent sera and sera from re-vaccinated individuals. A difference in specificity of antibodies reacting with INV and EEV was detectable by SRDT. The SRDT provides a simple, reproducible and specific test for detection of antibodies against vaccinia or variola virus, but the technique requires large quantities of virions.

Animals↗