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Biomedical subjects

R C Sutherland

Publications and source records attributed to R C Sutherland.

12 recordsLinked to original sources
PubMed1992

Statement: occupational therapy services in work practice.

Occupational therapy practitioners focus on the individual's ability to participate in productive occupations throughout their life span. Through prevention, assessment, and intervention strategies, occupational therapy practitioners often collaborate with other members of the health care team and assist persons to optimize their ability to engage in purposeful occupation while facilitating a safe and successful entry into or return to work.

Accidents, Occupational↗
PubMed1988

Oxytocin release evoked by electrical stimulation of the medial forebrain in the rat: analysis of stimulus parameters and supraoptic neuronal activity.

The role of the medial forebrain area (vertical limb of the diagonal band, medial septum and medial nucleus accumbens) in the control of oxytocin secretion in lactating rats was investigated. Electrical stimulation of the medial forebrain evoked a reproducible rise in intramammary pressure, equivalent to that caused by i.v. injection of 1 mU oxytocin. No pressor effect accompanied this response. Radioimmunoassay of plasma samples showed that stimulation caused a significant rise in the concentration of circulating oxytocin. The effects of changing the parameters of stimulation to the medial forebrain were compared with those evoked by stimulation of the neural stalk. The optimal frequency for stimulation of the forebrain was found to be four-fold lower (10-20 Hz) than that for stimulation of the neural stalk (50 Hz). During continuous prolonged stimulation of the forebrain (20 Hz; 2 min) only a single transient response was obtained, whereas a protracted response was obtained as a result of prolonged stimulation of the stalk. Recordings were made from antidromically identified neurosecretory cells in the supraoptic nucleus. Electrophysiological responses to electrical stimulation of the medial forebrain were characterized by two main features. (1) Single-pulse stimulation produced only a small excitation (one or two action potentials), while high-frequency trains produced a profound facilitation of this response, with each pulse evoking short-duration 'bursting' behaviour in the supraoptic neurons. (2) During long trains of stimulation this frequency-dependent facilitation declined and could only be renewed after a period of rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1987

Prolonged electrical stimulation of the nipples evokes intermittent milk ejection in the anaesthetised lactating rat.

Intermittent and continuous electrical stimulation of the nipples elicited milk-ejection responses in the lactating rat. The responses occurred intermittently, with similar amplitudes and periodicity as those seen in suckled rats. The responses were always associated with synchronization of the electroencephalogram (EEG), but some rats with synchronized EEG activity did not milk eject during stimulation. Since continuous stimulation also resulted in intermittent milk ejection it seems unlikely that the periodicity of the reflex in suckled rats depends upon changes in the intensity of sensory stimulation. The techniques of nipple stimulation may be a useful method with which to study neural pathways and other phenomena such as gating involved in oxytocin release and milk ejection. The success of the technique depends on a variety of factors such as parameters of the stimulation and state of anaesthesia.

Anesthesia↗
PubMed1986

Composite lymphoma.

A case of composite lymphoma in a young female is described. The patient was found to have lymphocyte-predominant Hodgkin's disease at presentation, but subsequent staging laparotomy revealed coexistent but distinct Hodgkin's disease and diffuse large cell lymphoma in the spleen. Possible explanations for this rare occurrence are discussed, and the literature is reviewed.

Adult↗
PubMed1986

Changing characteristics of the milk-ejection reflex during pregnancy, lactation and after weaning in the rat.

The pattern of reflex milk ejection during suckling was investigated in anaesthetized Wistar rats at various stages of pregnancy, lactation and after weaning. Milk-ejection responses were measured using intramammary pressure recordings, and the amount of oxytocin released was estimated from log dose-response lines compiled from the mammary responses to exogenous oxytocin. The number of rats showing intramammary pressure responses to oxytocin increased on Day 22 of pregnancy (the day of parturition) and decreased at 8 days after weaning. The dose-response lines from pregnant animals were shallow, but steepened and shifted to the left during lactation and after weaning. Reflex milk-ejection responses during suckling were detectable in primigravid animals, indicating that birth of the litter and previous suckling experience are unnecessary for the immediate functioning of the reflex. Reflex milk-ejection responses improved during early lactation (such that the frequency and the amount of oxytocin released at each response were maximal at Day 10 of lactation), and subsequently declined in late lactation. Although the frequency of responses in animals 2 and 4 days after weaning was similar to that in late lactating animals, the amount of oxytocin released at each response had risen again to mid-lactation values. In animals undergoing a second pregnancy and lactation the pattern of change in the milk-ejection responses was similar to that of primiparous animals.

Animals↗
PubMed1985

Effects of water deprivation and deamino [8-D-arginine] vasopressin on [14C]2-deoxyglucose uptake by the hypothalamo-hypophysial system in mice with hereditary nephrogenic diabetes insipidus.

The effects of water deprivation and the injection of deamino [8-D-arginine] vasopressin (dDAVP) on the metabolic activity of the hypothalamo-neurohypophysial neurones of mice with inherited nephrogenic diabetes insipidus (DI +/+ Severe) have been investigated by quantitative autoradiography using the [14C]2-deoxyglucose (2-DG) technique. The relative metabolic activities (rma) of the paraventricular nuclei (PVN) and pars nervosa (PN) in severely diabetic mice were not significantly different from the rma of the PVN and PN in Non-severe or Normal mice, but the rma of the pars distalis (PD) was greater in the Severe mice than in the other two strains. Water deprivation (4-5 h) significantly increased the rma of the PVN and PN in Severe mice compared with those in Non-severe mice that had been similarly deprived of water. The increased rma of the PVN and PN produced by water deprivation in Severe mice was not reduced to normal by injection of dDAVP. The injection of dDAVP alone had no effect on the rma of the PVN or PN, but dDAVP injection alone, water deprivation alone, or both treatments combined decreased the rma of the PD in Severe mice. Neither the supraoptic nuclei (SON) nor any of the other 19 brain areas studied were affected, in terms of rma, by either water deprivation, injection of dDAVP, or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Rhabdomyosarcoma in a patient treated for metastatic germ cell tumour of the testis containing teratoma--a case report.

A patient who developed a rhabdomyosarcoma following apparently successful chemotherapy for metastatic germ cell testicular carcinoma is presented. This newly recognized association may be seen particularly in patients whose initial germ cell malignancy contains immature teratoma. Possible reasons for this are discussed. The findings in this patient suggest that re-biopsy of recurrent disease be undertaken wherever possible, particularly where immature teratoma was a feature of the initial histopathology. A proportion of relapsing patients as described may not in fact have recurrent germ cell malignancy, but may have developed high grade, and often chemoresistant sarcomas. These second tumours appear to have an extremely poor prognosis, unless amenable to complete surgical resection.

Adult↗
PubMed1985

Reappraisal of the influence of mammary distension on the frequency of milk ejection in the rat.

Experiments were performed to reinvestigate the importance of mammary engorgement for activation of the milk-ejection reflex in the rat. Reflex milk ejection (measured by intramammary pressure recordings during a 2-h suckling test under anaesthesia) was compared in rats with engorged mammary glands (15-h separation from the pups, followed by sham-removal of milk) and in rats with drained mammary glands (15-h separation, followed by milk removal using a foster litter and exogenous oxytocin). In experiment 1, multiple small (2 mu.) doses of oxytocin were used for milk removal: these were effective in emptying the mammary glands and caused no subsequent impairment or change in sensitivity of the mammary response to oxytocin. Using this draining procedure, no significant differences were observed in either the number or relative amplitude of the milk ejections, or the occurrence of pup stretch reactions between engorged and drained rats. Similar results were seen in experiment 2, where an identical draining protocol was used, but the rats were pretreated with propranolol before the suckling test. In experiment 3, large (250 mu.) oxytocin doses were used for milk removal, as in previous studies. Again mammary draining had no effect on milk ejection in a subsequent suckling test (with propranolol pretreatment). However, the number of stretch reactions shown by the pups was significantly (P less than 0.001) reduced from 8.6 +/- 1.4/2 h to 1.9 +/- 0.6/2 h. This effect probably related to long-term impairment of the oxytocin response of the mammary glands following the draining procedure, and could not be attributed to the draining per se.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

Endotoxin from Fusobacterium necrophorum of bovine hepatic abscess origin.

The endotoxic activity of Fusobacterium necrophorum bov 5 was investigated. The supernatant (S) fluid and cell wall (CW) preparation, obtained after differential centrifugation of the ruptured cell mass, were lethal for mice. The toxicity of the S fluid was stable during prolonged storage, treatment with formalin, and heating for 15 minutes at 80, 100, and 121 C, but was destroyed by alkaline hydrolysis with 0.25 N NaOH. The toxic factor was found in a high molecular weight (MW) fraction after gel filtration. The properties exhibited by the toxic S fluid resembled those of endotoxic lipopolysaccharide (LPS). Extracted and partially purified LPS (endotoxin) from F necrophorum bov 5 demonstrated a mouse median lethal dose (mouse LD50) of 16.8 mg/kg of body weight. The toxic LPS material, a high molecular weight moiety as estimated by gel filtration, was resistant to ribonuclease (RNase), deoxyribonuclease (DNase), and pronase treatment. A positive Shwartzman reaction (median skin lesion dose (SLD50) equal to 3.32 mug/kg of body weight) and biphasic fever response (minimal dose required to produce a fever index of 40 sq cm which falls on the linear portion of dose-response curve (FL40) equal to 0.41 mug/kg of body weight) further indicated the toxin was endotoxin in nature. The LPS from F necrophorum bov 5 was less toxic than Salmonella typhimurium LPS; but had considerable toxicity for experimental animals. The toxic activity of the partially purified F necrophorum bov 5 endotoxin was separated into 2 fraction regions by diethylaminoethyl (DEAE)-cellulose chromatography. The data provide evidence for the production of a potent endotoxin, possibly composed of more than one toxic component, which may be released upon cell disruption.

Animals↗