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Biomedical subjects

S L Robinson

Publications and source records attributed to S L Robinson.

34 records · Page 2Linked to original sources
PubMed1991

Morphine compared with diamorphine. A comparison of dose requirements and side-effects after hip surgery.

The dose requirements and side effects of morphine were compared with those of diamorphine administered by patient-controlled analgesia in 40 patients following elective total hip replacement. Patients were allocated randomly to receive in a double-blind manner either morphine or diamorphine for postoperative pain relief. There were no significant differences between the two groups with regard to postoperative sedation, nausea, well-being, pain relief and requirements for antiemetic drugs. The dose requirement for diamorphine was approximately 50% of that for morphine.

Adult↗
PubMed1991

Nausea and vomiting with use of a patient-controlled analgesia system.

The incidence of nausea and vomiting following patient controlled analgesia and intramuscular morphine injections on demand was compared in a double-blind randomised study of 32 healthy patients undergoing elective cholecystectomy. There were no significant differences between the two groups in mean 24 hour postoperative morphine consumption, subjective experience of pain, nausea and sedation assessed by visual linear analogue scoring, and the postoperative requirements for antiemetic therapy.

Adult↗
PubMed1989

Human pulmonary surfactant protein (SP-A), a protein structurally homologous to C1q, can enhance FcR- and CR1-mediated phagocytosis.

C1q, a subunit of the first component (C1) of the classical complement pathway, and the pulmonary surfactant protein SP-A are structurally homologous molecules, each having an extended collagen-like domain contiguous with a non-collagenous domain. It is the collagen-like region of C1q that binds to mononuclear phagocytes and mediates the enhancement of phagocytosis of opsonized particles by these cells. Because SP-A enhances the endocytosis of phospholipids by alveolar type II cells and alveolar macrophages, we examined whether these two molecules were functionally interchangeable. The phagocytosis of sheep erythrocytes opsonized with IgG or with IgM and complement was enhanced by the adherence of monocytes or macrophages, respectively, to SP-A. The enhanced response was dependent on the concentration of SP-A used for coating the surfaces, similar to that seen when monocytes were adhered to C1q-coated surfaces. Both the percentage of cells ingesting the opsonized targets and the number of targets ingested per cell increased with increasing concentrations of SP-A. No such enhancement was seen with cells adhered to albumin, iron-saturated transferrin, or uncoated surfaces. However, SP-A did not substitute for C1q in the formation of hemolytically active C1. C1q did not stimulate lipid uptake by alveolar type II cells or alveolar macrophages and had only a slight inhibitory effect on the binding of SP-A to alveolar type II cells. Thus, these results suggested that a function which requires interactions of both the collagenous and the non-collagenous regions (i.e. initiation of the classic complement cascade) could not be mimicked by a protein sharing structural macromolecular similarity but lacking sequence homology in the non-collagen-like region. However, SP-A could substitute for C1q in stimulating a function previously shown to be mediated by the collagen-like domains of the C1q molecule.

Cells, Cultured↗
PubMed1989

Prolactin or dopamine mediates the induction of puberty by long days in female ferrets.

The role of PRL in sexual maturation of female ferrets was examined in these studies. Longitudinal profiles of PRL secretion were obtained by thrice weekly blood sampling of intact female ferrets undergoing photoperiod-stimulated development as well as age-matched control females which remained in nonstimulatory short days. Two additional groups of intact females, one in each photocycle, were treated with the dopamine agonist drug bromocriptine throughout the study. The relationship between developmental changes in PRL secretion and the critical pubertal decrease in the efficacy of estradiol (E2) inhibitory feedback on LH secretion was studied by using additional groups of females which were ovariectomized and treated with E2 implants (OVX + E2). These latter females were housed in either long or short day photoperiods; some were treated with bromocriptine, the remainder were treated with the vehicle only. Results of this study revealed that PRL secretion in ferrets does not change acutely with an abrupt increase in day length. After 4 weeks of exposure to long days, however, a marked increase in PRL secretion occurred. This increased secretion of PRL was contemporaneous with the onset of pubertal ovarian activity in intact females and with the escape of LH from the negative feedback of E2 in OVX + E2-treated females. The further observation that pharmacological blockade of the long day-induced rise in PRL secretion also prevented the pubertal onset of ovarian activity suggested that PRL may play a critical role in the induction of puberty in this species. The mechanism by which bromocriptine prevented puberty induction was illustrated in the OVX + E2-treated ferrets in stimulatory photoperiod. The drug treatment prevented the pubertal decrease in the efficacy of E2 negative feedback on LH. These studies suggest an important interaction between the dopamine-PRL system and the GnRH-LH system in the regulation of sexual maturation of female ferrets.

Animals↗
PubMed1988

Sexual maturation in the female ferret: circumventing the gonadostat.

The purpose of this study was to examine the role of circulating 17 beta-estradiol in the regulation of pituitary gonadotropin secretion and, hence, ovarian maturation in immature female ferrets. The hypersensitive negative feedback relationship between the ovaries and the hypothalamo-pituitary axis in developing ferrets was disrupted by infusion of a specific antiserum to 17 beta-estradiol. The effect of this treatment on gonadotropin secretion and ovarian morphology was contrasted with that observed in intact age-matched control females treated with a nonimmune gamma-globulin preparation. Infusion of the antibody into intact immature ferrets caused, within 48 h, an increase in pulsatile secretion of LH to 0.67 +/- 0.06 pulses/h over that observed in intact females treated with control gamma-globulin (0.13 +/- 0.06 pulses/h). This increase in pulse frequency was similar to that observed 48 h after ovariectomy of young animals (0.70 +/- 0.12 pulses/h). Furthermore, this level of gonadotropin secretion in antibody-treated animals resulted in stimulation of antral follicle growth in ovaries of these females. Ferrets treated with specific antiserum to 17 beta-estradiol showed a significant increase in numbers of ovarian follicles greater than 0.3 mm in diameter compared to those in ovaries of females treated with control gamma-globulin. These data strongly suggest that the limiting event at puberty in the ferret is the rise in gonadotropin secretion which is allowed by the pubertal decrease in efficacy of 17 beta-estradiol to inhibit gonadotropin secretion.

Animals↗
PubMed1987

Age differences in the relation between controllability and coping.

This study was conducted to examine the relation between generalized and domain-specific locus of control and coping strategies as moderated by age differences. Adolescents through older adults were given measures of controllability and coping for both relationship and achievement contexts. For domain-specific measures only, older adults perceived the cause of stressors in both contexts as less controllable than did all other participants. However, no age difference was found in controllability of the outcome. Domain-specific measures were better predictors of coping than generalized measures of locus of control. Domain-specific attribution measures were most predictive of the coping mechanism self-blame, and this relation was moderated by age and context. Controllability of outcome predicted the use of self-blame among adolescents and, to a lesser degree, among younger adults; internal locus of causality of the stressful event predicted self-blame among older adults.

Achievement↗
PubMed1987

A study of spontaneous sexual maturation of the female ferret.

Although ferrets are long-day breeders, females reared exclusively in nonstimulatory short days will undergo spontaneous sexual maturation by 30-50 wk of age. In the following report, this spontaneous sexual maturation of ferrets was studied to determine mechanisms regulating sexual maturation in nonstimulatory photoperiods. Study of ovariectomized females treated with low, constant levels of estradiol suggest that a marked decrease in the efficacy of estradiol to inhibit luteinizing hormone secretion occurs shortly before sexual maturity becomes evident in intact controls (both groups housed in short days). During this long juvenile period, a marked increase in body weight occurred, but ovarian responsiveness to exogenous gonadotropin did not change. Older, larger females did respond more rapidly to stimulatory photoperiod than did younger females. These studies suggest that the mechanisms of spontaneous puberty in ferrets are likely the same as those regulating photoperiod-stimulated puberty in this species.

Animals↗
PubMed1985

Influence of day length and endocrine status on luteinizing hormone secretion in intact and ovariectomized adult ferrets.

The purpose of this study was to examine the pituitary-ovarian relationship of both estrous and anestrous female ferrets. The endocrine status of the animals was induced by manipulating photoperiod: females in estrus were housed in long days (16L:8D); females in anestrus were housed in short days (8L:16D). For studies of intact animals in both photoperiods, plasma luteinizing hormone (LH) levels were quantified in blood samples collected from adult ferrets at 5-min intervals over a 24-h period. Similar groups of females (estrous and anestrous) were ovariectomized (while remaining in their assigned photoperiods) and blood samples were collected at 5-min intervals for 4-h periods on Days 1, 2, 4, 10, 17, and 35 after ovariectomy. Intact, estrous females exhibited continuously low or undetectable levels of LH with no evidence of episodic secretion. Ovariectomy of these estrous animals resulted in rapid onset (within 24 h) of episodic LH secretion, with pulses occurring in excess of 1 pulse/h. No substantial further change in frequency or amplitude of pulses occurred in these females from 1 to 35 days postovariectomy. In contrast, intact anestrous ferrets exhibited clear episodic LH secretion at a frequency of about 0.4 pulses/h. Removal of ovaries from these females caused no change in LH secretion for 24-48 h, after which LH pulses gradually increased in frequency. By 18 days after ovariectomy, LH patterns were indistinguishable among ovariectomized females in long and short days. These studies suggest a major site of ovarian negative feedback on LH secretion during anestrus is the hypothalamus, whereas the site of the ovarian feedback in estrous females is not yet evident.

Animals↗
PubMed1985

Halothane anesthesia reduces pulmonary function in the newborn lamb.

To study the effects of anesthesia on respiratory function of the neonate, the authors investigated the effect of breathing 100% oxygen and of breathing oxygen plus 0.75 MAC halothane on functional residual capacity, lung and airway resistance, expired minute volume, work of breathing, lung compliance, and blood gases and pH in nine 5-8-day-old, 4.6-7.7-kg lambs. Breathing 100% oxygen increased PaO2 but had no effect on PaCO2, minute ventilation, or lung mechanics. Three-fourths MAC halothane depressed minute ventilation 34% +/- 13% (P less than 0.05) and increased PaCO2 50% +/- 5% (P less than 0.05). Lung and airway resistance increased 59% +/- 26% (P less than 0.05); work of breathing decreased (P less than 0.05); and lung compliance was unchanged. Functional residual capacity was reduced 32% +/- 6% (P less than 0.05), which may be due to loss of diaphragm and intercostal muscle function and to an inability to take deep breaths. The authors conclude that 0.75 MAC halothane significantly impairs the pulmonary function of lambs who breathe spontaneously. Similar changes in human infants could account for the hypoxemia and hypercarbia that often are seen during anesthesia.

Airway Resistance↗
PubMed1985

A rise in tonic luteinizing hormone secretion occurs during photoperiod-stimulated sexual maturation of the female ferret.

This study determined whether a rise in tonic secretion of LH occurred before long day-induced precocious puberty of the female ferret. Twenty immature females were assigned to 1 of 2 photoperiods at 15 weeks of age. Ten ferrets were placed in a long day, stimulatory photoperiod (16 h of light, 8 h of darkness) to induce sexual maturation, and 10 remained in the nonstimulatory photoperiod (8 h of light, 16 h of darkness) for the duration of the study. Intensive blood sampling regimens (every 10 min for 8 h) were conducted at selected times after the onset of long days to permit definition of detailed secretory patterns of plasma LH. Females in each photoperiod were sampled from chronic jugular venous catheters approximately twice weekly until puberty was evident in females housed in long days. The end point for determination of the pubertal onset of adult ovarian function was the appearance of estrogen-sensitive vulvar edema. Results show a marked increase in frequency of episodes of LH secretion per 8-h interval in females undergoing sexual maturation. No such change in frequency occurred in unstimulated females housed continuously in short days, nor did the short day females exhibit vulvar edema. Further, the increment in LH secretion occurred before either vulvar edema or a significant increase in plasma estradiol levels was observed. Therefore, the rise in LH secretion that occurs after several weeks of exposure to a long day photoperiod may well be an important drive to maturational changes in ovarian function.

Analysis of Variance↗
PubMed1985

Eye classification, sex, and math anxiety in learning disabled children: behavioral observations on conservation of volume.

Benbow and Benbow suggest that myopia and maleness are advantages in mathematical giftedness; however, the influence of these biological correlates on learning disabilities is not yet as clearly defined. 29 learning disabled children (aged 7-13 yr; eye class diagnosed) performed two Piagetian tasks on conservation of volume, one using numbered blocks to rebuild an original house whose "rooms" were cued by an illogically ordered system, and one using plain blocks to recreate an unnumbered house. A modification of the Preschool Observation Scale of Anxiety was used to observe frequencies of overt physiological behavioral indicators of anxiousness during task performances. No significance was noted by eye class; however, a significant interaction of sex by task did occur. Means differed by sex significantly on the numbered tasks. Implications are discussed in terms of certainty times versus correctness and facilitative versus debilitative anxiety.

Adolescent↗
PubMed1983

The cardiovascular effects of vecuronium (ORG NC45) and pancuronium in patients undergoing coronary artery bypass grafting.

Vecuronium is a new nondepolarizing muscle relaxant which has been shown to cause no significant cardiovascular effects. Utilizing invasive monitoring in patients undergoing coronary artery bypass grafting, the authors compared the cardiovascular effects of vecuronium (0.28 mg/kg) in seven anesthetized patients with those of pancuronium (0.1 mg/kg) in five anesthetized patients. This dose of pancuronium represents three times its ED90 (dose producing a 90% depression of evoked twitch tension), while the vecuronium dose represents twelve times its ED90. This relatively large dose of vecuronium was chosen deliberately in an attempt to manifest any possible cardiovascular effects. Following administration of vecuronium, cardiac output increased 9% and systemic vascular resistance decreased 12%, while pancuronium produced a significantly greater 17% increase in cardiac output without change in systemic vascular resistance. Heart rate and systemic mean arterial pressure did not change following vecuronium, while increasing 22% and 24%, respectively, following pancuronium. The authors conclude that large doses of vecuronium have minimal cardiovascular effects and thus offer an advantage over pancuronium in patients anesthetized for coronary artery surgery.

Adrenergic beta-Antagonists↗