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Biomedical subjects

S Thornton

Publications and source records attributed to S Thornton.

At least 109 records · Page 6Linked to original sources
PubMed1989

Amniotomy-induced labour is not mediated by endogenous oxytocin.

A technique for complete oxytocinase inhibition has been combined with a rapid serial sampling strategy to determine the plasma oxytocin concentration in eight women undergoing amniotomy for the induction of labour at term and in eight control women. Amniotomy was not associated with an increase in plasma oxytocin concentration. Furthermore, the concentrations were not increased for 20 min following the procedure. Labour was not established in any patient by the end of the 30-min study period.

Adolescent↗
PubMed1989

Arginine vasopressin and oxytocin responses to insulin-induced hypoglycemia in type 1 (insulin-dependent) diabetes.

In normal humans, arginine vasopressin and oxytocin are released acutely from the posterior pituitary gland in response to hypoglycemia, and their release may assist counterregulation. The responses of these hormones to insulin-induced hypoglycemia were measured in 16 insulin-dependent diabetic patients with no autonomic neuropathy (8 patients who had been diabetic less than 5 yr and 8 patients who had been diabetic greater than 15 yr) and in 6 normal subjects. The time of the onset of hypoglycemia and the mean blood glucose nadirs were similar in all groups, but the blood glucose recovery was delayed in the diabetic patients. In the normal subjects plasma arginine vasopressin rose from a mean basal value of 0.4 +/- 0.2 (+/- SE) pmol/L to a maximum of 1.3 +/- 0.6 pmol/L, and plasma oxytocin rose from 0.7 +/- 0.1 pmol/L to a maximum of 1.2 +/- 0.2 pmol/L 30 min after the onset of hypoglycemia. The plasma arginine vasopressin and oxytocin concentrations after hypoglycemia were significantly higher in both of the diabetic groups compared with those in the normal group. Arginine vasopressin and oxytocin rose in all control subjects after hypoglycemia. The individual hormonal profiles in the diabetic patients were variable, with an exaggerated rise of oxytocin in some diabetic patients and no rise in others. The arginine vasopressin responses were exaggerated in all of the diabetic patients. There was no correlation between the hormonal responses and the duration of diabetes. The exaggerated plasma arginine vasopressin and oxytocin responses to hypoglycemia in diabetic patients may indicate the failure of a normal inhibitory mechanism which modulates hormonal secretion or a compensatory response to impaired glucose recovery.

Adolescent↗
PubMed1989

Osmoregulation of vasopressin secretion in the insulin-withdrawn streptozotocin-treated diabetic rat.

To investigate whether hyperglycaemic ketoacidotic diabetic rats continue to osmoregulate the secretion of arginine vasopressin (AVP), male Wistar rats were injected with streptozotocin (150 mg/kg body weight). Rats rendered diabetic were maintained on protamine-zinc insulin (PZI) for 11 days (insulin-treated rats; n = 35), after which PZI was withdrawn for 72 h in half the rats (insulin-withdrawn rats). Insulin-withdrawn and -treated rats were divided into two groups; one was injected i.p. with distilled water (20 ml/kg) and the other with hypertonic saline (500 mmol NaCl/l; 20 ml/kg), and killed 30 min after injection. Insulin-withdrawn rats (water loaded and osmotically stimulated) were hyperglycaemic (16.5 +/- 0.8 and 16.5 +/- 0.9 mmol glucose/l respectively) and ketotic (2077 +/- 664 and 1474 +/- 170 mumol acetoacetate/l respectively). Insulin-treated rats were euglycaemic and non-ketotic. Osmotic manipulation caused similar changes in plasma sodium in both insulin-withdrawn and -treated rats. Plasma AVP was low in the water-loaded rats (0.6 +/- 0.1 and 4.5 +/- 0.9 pmol/l in the insulin-treated and -withdrawn rats respectively) and increased in rats injected with hypertonic saline (1.2 +/- 1.8 and 35.2 +/- 17.9 pmol/l respectively). There was no evidence of hypotension and hypovolaemia in any group of rats. Linear regression analysis defined the functions: plasma AVP = 2.56 (plasma Na-141), r = +0.63, P less than 0.01 for hyperglycaemic ketotic rats; plasma AVP = 0.83 (plasma Na-146), r = +0.78, P less than 0.001 for insulin-treated animals. The slopes and abscissal intercepts were significantly (P less than 0.05) different.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Plasma oxytocin during third stage of labour: comparison of natural and active management.

The incidences of postpartum haemorrhage and retained placenta have decreased with the use of synthetic oxytocin and controlled cord traction. Whether such treatment is valuable is open to question because of the lack of clinical and physiological studies. The physiological effects of synthetic oxytocin on plasma concentrations of oxytocin and events during delivery were assessed. Plasma oxytocin concentration was determined in serial samples during the late second stage and throughout the third stage of labour in 25 women. Ten women received combined ergotamine and synthetic oxytocin intramuscularly and 15 were not treated. The geometric mean plasma oxytocin concentration significantly increased in the women given oxytocin when measured before and after delivery of the fetal anterior shoulder (3.1 (SD 2.0) pmol/l before and 15.9 (2.7) pmol/l after). Six of the women who did not receive treatment showed a significant increase in geometric mean plasma oxytocin concentration before and after delivery of the fetal shoulder (3.2 (2.0) pmol/l before and 6.4 (2.0) pmol/l after) and nine did not show an increase (geometric mean 2.4 (3.1) pmol/l before and 2.2 (2.2) pmol/l after). Of these nine women, two had an abnormal third stage of delivery; one woman had a postpartum haemorrhage and one required manual removal of the placenta. As it is impossible to predict which women will show a rise in the plasma concentration of endogenous oxytocin, intramuscular oxytocin should be given routinely.

Female↗
PubMed1987

Reminiscence: a critical review of the empirical literature.

The empirical evidence concerning the prevalence and function of reminiscence among the elderly is reviewed and the relevance of such activity for clinical populations is evaluated. Variations in the ways in which reminiscence is defined and methods of eliciting reminiscence activity are described. Data on frequency of reminiscence and its relationship to age are discussed. Studies investigating the functions of reminiscence are divided into three groups according to experimental design and their findings critically reviewed. It is concluded that there is little evidence of an age-specific process of reminiscence, that the functions of such a process are unclear and that the role of reminiscence as a therapeutic activity is in doubt.

Adolescent↗
PubMed1984

Human adult endothelial cell growth in culture.

The purpose of the present study was to culture human adult endothelial cells (HAECs) on a long-term basis in the laboratory. Previous inability to accomplish this has been the major impediment to the in vitro study of endothelialization of prosthetic grafts with human cells, a problem of significant clinical relevance. We have been successful in developing a technique that allows HAECs from human adult arteries, veins, and capillaries to proliferate vigorously in culture for up to 80 population doublings. HAECs are grown on a gelatin surface (medium 199 containing 20% fetal calf serum). Heparin and endothelial cell growth factor (ECGF) are required for optimal growth. With this technique, which will be described in detail, over 10(23) HAECs can be produced from each 1 cm2 of vascular tissue. This makes large numbers of HAECs available for high-density seeding on prosthetic grafts prior to implantation. It also permits for the first time with human cells the in vitro study of prosthetic grafts--HAEC interactions and the factors that enhance optimal growth and adherence to prosthetic materials. It is hoped that identification of the factors promoting graft endothelialization in combination with high-density seeding will lower graft thrombogenicity and therefore result in greater graft longevity than has been possible heretofore.

Adult↗
PubMed1982

Comparison of ultrasonic to hand instruments in the removal of subgingival plaque.

The primary objective of this study was to compare the effectiveness of hand and ultrasonic instrumentation in removing subgingival plaque. Twenty-four teeth in five patients were randomly assigned to be scaled by hand instruments, scaled by ultrasonic instruments, or uninstrumented as a control The subgingival tooth surface was delineated by a groove, and the teeth were then extracted for periodontal reasons. The percentage of plaque area relative to the total surface area of the side of the tooth was computed. No significant difference was found between the two methods in removing subgingival plaque. Furthermore, neither method removed all of the plaque.

Coloring Agents↗
PubMed1980

Active and passive avoidance learning in controls and schizophrenic patients on racemic propranolol and neuroleptics.

Normal controls and schizophrenic patients on propranolol as sole drug or combined with neuroleptics showed superior active and passive avoidance learning to schizophrenic patients who were medicated with conventional neuroleptics only. Active avoidance involved responding quickly, passive avoidance withholding a response to avoid an unpleasant noise and reacting to the appropriate stimulus. This may reflect an improvement brought about by propranolol in the limbic regulation of stimulus and response processes.

Adult↗
PubMed1980

Effectiveness of urine surveillance as an adjunct to outpatient psychotherapy for drug abusers.

Twenty-nine polydrug abusers were randomly assigned to three out-patient treatment groups after inpatient detoxification. The groups were outpatient psychotherapy (1) with urine surveillance, (2) without surveillance, and (3) waiting list control. Tests were administered before and 3 months after outpatient treatment began. All groups made positive changes during treatment including significant reduction in drugs abused and numbers of subjects reporting less time spent in illegal activity. Notable significant differences were Group 3's reduction in social introversion vs Groups 1 and 2, and Group 1's retaining fewer drug-using friends and showing greatest reduction in barbiturate use frequency vs Groups 2 and 3. Experimenters concluded urine surveillance was somewhat helpful as an adjunct to outpatient psychotherapy but suggested its effect could be amplified by employing more rigorous surveillance procedures, especially if contingency contracting were utilized.

Adolescent↗