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Biomedical subjects

S Stock

Publications and source records attributed to S Stock.

At least 19 recordsLinked to original sources
PubMed1992

Role of endoscopic retrograde cholangiopancreatography in the investigation of pain after cholecystectomy.

Patients who continue to have or who develop abdominal pain after apparently successful cholecystectomy pose diagnostic difficulties. This study reports 384 such patients, investigated by endoscopic retrograde cholangiopancreatography (ERCP). There were 146 patients with abdominal pain alone with no previous history of common bile duct (CBD) exploration, of whom only 17 (11.6 per cent) had CBD stones on ERCP. Bile duct calculi were present in 76 of 140 patients (54.3 per cent) with abnormal biochemical findings (raised alkaline phosphatase and/or amylase level) and in 34 of 57 (60 per cent) with an abnormality detected on ultrasonography or intravenous cholangiography. A combination of biochemical and radiological abnormalities was present in 37 patients and was associated with CBD stones in 28 (76 per cent). Patients who had undergone CBD exploration represented a special group, of whom the majority (75 per cent) had common duct stones at ERCP even in the absence of biochemical and radiological abnormalities. ERCP is a useful investigation in patients with persistent postcholecystectomy symptoms. Other features in addition to pain or a history of CBD exploration may be relevant to the decision to perform ERCP in the investigation of these patients.

Abdominal Pain↗
PubMed1991

Plasma levels of oxytocin during the menstrual cycle, pregnancy and following treatment with HMG.

In 15 women investigated during the follicular, ovulatory and luteal phases of the menstrual cycle, only small variations in plasma levels of oxytocin were found. There was no mid-cycle surge in oxytocin levels. A parallel variation in oxytocin and oestradiol levels was found in five of the women. In 10 women examined every 4th week during gestation starting at week 12, a small but significant increase in oxytocin levels was found. Pronounced fluctuations in oxytocin levels were observed in four of the pregnant women. These fluctuations were independent of the stage of gestation and were also observed in three of the menstruating women. Seven out of 12 women treated with human menopausal gonadotrophin exhibited a marked elevation of oestradiol levels; oxytocin levels also increased and were significantly elevated when the oestradiol level exceeded 2 pmol/ml. Oxytocin levels were higher in the pregnant and human menopausal gonadotrophin-treated women than in the menstruating women. The oxytocin levels appeared to be only partly related to the oestradiol level. It is possible that the stimulatory effect of oestradiol is antagonized by a concomitantly high progesterone level. Alternatively, there may not be a linear dose-effect relationship between oestradiol and the release of oxytocin.

Estradiol↗
PubMed1990

Effects of oxytocin on in vivo release of insulin and glucagon studied by microdialysis in the rat pancreas and autoradiographic evidence for [3H]oxytocin binding sites within the islets of Langerhans.

In the present investigation it was studied whether oxytocin administered directly in the pancreas of the rat stimulates the release of insulin and glucagon. In order to study such effects in vivo, a new experimental model applying the microdialysis technique was developed. To test the validity of the method, glucose or arginine were infused i.v. and it was shown that perfusate concentrations of insulin and glucagon increased significantly to 344 and 292% of basal overflow, respectively. Administration of oxytocin via the dialysis probe into the splenic portion of the pancreas resulted in significant elevations of insulin and glucagon concentrations to 210 (P less than 0.05) and 528% (P less than 0.01), respectively. The present study also includes a combined autoradiographic and immunohistochemical investigation of binding sites for oxytocin in the rat pancreas. A high density of [3H]oxytocin binding was present in the periphery of the islets of Langerhans, corresponding to the localization of the glucagon-producing alpha-cells. Both oxytocin and arginine(A)-vasopressin displaced [3H]oxytocin. The IC50 values were 10 and 180 nM, respectively. In conclusion, the oxytocin-induced release of insulin and glucagon as previously demonstrated in a number of species, may be due to a stimulation exerted by the peptide directly within the pancreas.

Animals↗
PubMed1989

Interaction between gastrin-17 and oxytocin on plasma levels of insulin, glucagon and glucose in conscious dogs.

The aim of the present study was to investigate how infusion of gastrin-17 and oxytocin affects plasma levels of insulin, glucagon and glucose in order to elucidate how the two hormones contribute to metabolic changes seen in situations where they are released, e.g. feeding and suckling during lactation. Thus, gastrin-17 (0.5 and 2.0 nmol kg-1 h-1) and oxytocin (0.11 and 1.1 nmol kg-1 h-1) were infused separately or simultaneously into conscious dogs. Both gastrin-17 and oxytocin induced significant, dose-dependent increases in insulin levels. An additive effect on insulin levels was obtained when gastrin-17 and oxytocin were infused simultaneously. Glucagon levels were not affected by gastrin-17 whereas infusion of 1.1 nmol kg-1 h-1 of oxytocin was followed by a significant increase. In contrast to a slight transient increase in the glucose level induced by oxytocin, infusion of gastrin-17 caused a sustained period of hypoglycaemia. Thus, infusion of gastrin-17 and oxytocin, respectively, gave rise to different ratios between circulating concentrations of insulin and glucagon reflected in different effects on the glucose level. The gastrin-induced hypoglycaemia could reflect that gastrin, via a release of insulin, promotes storing of glucose, e.g. in connection with feeding. That infusion of oxytocin caused a parallel increase in insulin and glucagon levels together with a slight increase in the glucose level could imply that oxytocin favours mobilization of glucose, e.g. during lactation.

Animals↗
PubMed1989

Plasma levels of gastrin, somatostatin, VIP, insulin and oxytocin during the menstrual cycle in women (with and without oral contraceptives).

The aim of the present study was to investigate whether plasma levels of gastrin, somatostatin, insulin, oxytocin, VIP and blood glucose levels vary during the menstrual cycle. Therefore, 19 healthy menstruating women (5 of whom were on low-dose oral contraceptives, o.c.) were blood sampled every second to third day during the menstrual cycle. Hormone levels were measured with radio-immunoassay. Gastrin, insulin, VIP and blood sugar levels remained unchanged during the menstrual cycle. Mean somatostatin levels were significantly lower in women receiving o.c. than in women without such medication (p less than 0.05). In women on o.c., somatostatin concentrations were also significantly lower during the menstrual week, than during the rest of the period (p less than 0.01), but in women without o.c., no such change occurred. Mean oxytocin levels were significantly higher in women on o.c. (p less than 0.001) and in these women, oxytocin levels recorded during the menstrual week were significantly lower than during the rest of the period (p less than 0.02). Systolic and diastolic blood pressure values were also significantly higher in women on o.c. (p less than 0.05 and p less than 0.01). In conclusion, these data show that basal plasma concentrations of gastrin, somatostatin, VIP, insulin and glucagon do not vary during the menstrual cycle. However, ingestion of low-dose oral contraceptives causes a significant decrease of somatostatin concentrations and a significant increase in oxytocin levels, suggesting that low doses of estrogens and/or gestagens may influence digestive and metabolic processes.

Adult↗
PubMed1989

Effect of nipple stimulation on uterine activity and on plasma levels of oxytocin in full term, healthy, pregnant women.

The effect of nipple stimulation on uterine activity, foetal heart rate and plasma oxytocin level in healthy full term pregnant women was studied. Ten women in weeks 38-39 of pregnancy stimulated their nipples for 30 min. Nine of the ten experienced uterine contractions. One woman showed signs uterine hyperactivity (frequent contractions) and foetal heart rate decelerations. Blood samples were drawn at 15 s intervals during 5-6 contractions and oxytocin levels were measured with radioimmunoassay. Oxytocin levels rose significantly during the nipple stimulation and short bursts of oxytocin were recorded during contractions. Nipple stimulation has been used to induce labour and our data may suggest that oxytocin released in response to such stimulation is responsible for the contractions induced.

Adult↗
PubMed1989

Elevated plasma levels of oxytocin in women taking low-dose oral contraceptives. Identification of the plasma oxytocin with high performance liquid chromatography.

The aim of the present study was to investigate whether low-dose oral contraceptives affect oxytocin concentrations in plasma. Twenty women participated in an open cross-over study. Six consecutive blood samples were drawn twice, with a 4-week interval, in the luteal phase of the menstrual cycle when the women were/were not taking oral contraceptives. Plasma levels of oxytocin were analysed with a radio-immunoassay specific for oxytocin. A significant increase in oxytocin concentrations was observed following ingestion of oral contraceptives (p less than 0.02). Women with the highest oxytocin levels during a normal menstrual cycle increased their levels the most when on oral contraceptives. Analysis with high performance liquid chromatography demonstrated that immunoreactive oxytocin found in plasma, whether with or without oral contraceptives, co-eluted with synthetic oxytocin standard. An interesting possibility could be that the mental side effects and effects on glucose metabolism occurring after treatment with oral contraceptives might be related to elevated oxytocin levels, since metabolic and CNS effects of oxytocin are known.

Adult↗
PubMed1989

Elevated plasma levels of oxytocin in obese subjects before and after gastric banding.

Impaired glucose tolerance and hyperinsulinaemia are common features of obesity. Since oxytocin has been shown to influence glucose metabolism and insulin secretion, the objective of the present study was to investigate whether the plasma level of oxytocin is elevated in obese subjects and if so, whether it is affected by weight reduction following gastric banding. Repeated blood samples were collected in connection with ingestion of a liquid test meal from subjects weighing about 130 kg. Normal weight subjects were tested likewise. Further tests were performed on obese subjects 6 months after operation with gastric banding and a subsequent weight reduction of about 30 kg. Plasma levels of oxytocin were measured by radioimmunoassay. It was found that plasma levels of oxytocin were 4-fold higher in the obese subjects when compared to the control subjects. Analysis with high performance liquid chromatography demonstrated that the oxytocin-like material, as determined by radioimmunoassay, in extracted plasma from one obese subject coeluted with synthetic oxytocin standard. Ingestion of a test meal did not seem to influence oxytocin levels. The mean oxytocin level was equally elevated in male and female obese subjects. Following operation oxytocin levels decreased significantly, but were still significantly higher than in the control subjects. The mechanism behind the hyperoxytocinaemia and possible consequence of it remain obscure.

Female↗
PubMed1988

Increased plasma levels of oxytocin in response to afferent electrical stimulation of the sciatic and vagal nerves and in response to touch and pinch in anaesthetized rats.

This study was performed in order to investigate whether activation of sensory fibres within the sciatic and vagal nerves might influence the release of oxytocin. In anaesthetized rats the sciatic and vagal nerves were stimulated electrically in an afferent direction with a variety of stimuli. Rats were also stroked on their backs or nociception was inflicted by pinching a foot. Plasma oxytocin levels were measured with a highly sensitive radioimmunoassay in samples drawn from the carotid artery. Afferent electrical stimulations of both sciatic and vagal nerves at 5 V, 0.2-2 ms and 3-10 Hz caused immediate significant elevations of oxytocin levels. Thus, basal levels increased by 30-184%. Furthermore, in response to touch and nociceptive stimuli, oxytocin levels rose by 181% and 206%, respectively. These data indicate that oxytocin can be released by stimulation of peripheral nerves originating in the skin and/or muscle and in the gastrointestinal tract and thus these organs may be involved in the control of oxytocin secretion.

Afferent Pathways↗
PubMed1987

The effect of oral contraceptive pills on levels of oxytocin in plasma and on cognitive functions.

Millions of healthy women use combined oral contraceptives (o.c.) for decades. In spite of that, little is known about their possible effects on cognitive functions. In this open cross-over study, 20 women were examined twice at four-week intervals at a fixed period of the menstrual cycle when they were and when they were not taking o.c. They were examined with a test-battery to assess cognitive functions. Blood samples were taken before and after breakfast to assess levels of oxytocin and prolactin. A significant increase in levels of oxytocin was registered when the women were on o.c. There was no significant difference in performance on the psychometric tests when the participants were on o.c. compared to when they were without o.c.

Adult↗
PubMed1987

L-vasopressin inhibits oxytocin-induced increases of plasma levels of insulin conscious dogs.

Oxytocin is known to increase plasma levels of insulin, glucagon and glucose in dogs. Plasma levels of vasopressin rise during stressful conditions. Since vasopressin counteracts several oxytocin-induced effects, it was decided to study how vasopressin influences the oxytocin-induced elevation of plasma levels of insulin, glucagon and glucose. Therefore oxytocin at 0.11 (which gives rise to physiological plasma concentrations) was infused i.v. for 10 min into fasted, conscious dogs either alone or in combination with 0.033 or 0.17 nmol kg-1 h-1 of L-vasopressin. Accordingly, 1.1 nmol kg-1 h-1 of oxytocin was infused alone or in combination with 0.67 or 1.7 nmol kg-1 h-1 of L-vasopressin. Repeated blood samples were drawn during and after the infusions and insulin and glucagon levels were determined by radioimmunoassay. Plasma levels of insulin increased three- and six-fold in response to 0.11 and 1.1 nmol kg-1 h-1 of oxytocin, respectively, and the elevations were inhibited by L-vasopressin. Slight (1.5-fold) increases in plasma levels of glucagon were observed following 0.11 and 1.1 nmol kg-1 h-1 of oxytocin, although the effect was significant only after the latter dose. Concomitant infusion with L-vasopressin did not markedly influence the effect caused by oxytocin. Small, insignificant increases in blood glucose levels were induced by both doses of oxytocin. These effects were not affected by concomitant infusions of L-vasopressin. The insulin levels rose before glucose levels suggesting that oxytocin stimulates the release of insulin without a previous rise in glucose levels. In conclusion, it has been shown that vasopressin, in amounts which give rise to physiological plasma concentrations, inhibits oxytocin-induced effects on insulin levels, and that oxytocin stimulates the release of insulin via a mechanism which is independent of elevations in blood glucose levels.

Animals↗
PubMed1985

Plasma levels of oxytocin increase in response to suckling and feeding in dogs and sows.

The objective of the present study was to investigate whether oxytocin is released in response to feeding in analogy to the response induced by suckling. Therefore, repeated plasma samples were drawn from dogs and pigs during feeding and suckling and oxytocin levels were determined by radioimmunoassay. As expected suckling gave rise to immediate and short-lasting increases of oxytocin levels in both species. More surprisingly, feeding in female and male dogs as well as in lactating sows was accompanied by a similar-sized rise of oxytocin levels. The oxytocin peak sometimes occurred before the actual period of suckling or feeding, suggesting that the output of oxytocin had been conditioned to visual, olfactory or auditory stimuli associated with both types of situations. It is well known that oxytocin is released in lactating animals in response to touching of the teats. It is possible that also the presence of food in the gastro-intestinal tract activates neurogenic mechanisms which stimulates the release of oxytocin. Since oxytocin causes a release of insulin and VIP (vasoactive intestinal polypeptide), peptides which appear in the circulation following both suckling and feeding, it is suggested that oxytocin may be involved in the control of the suckling- and feeding-related output of these peptides.

Animals↗
PubMed1985

Oxytocin infusions increase plasma levels of insulin and VIP but not of gastrin in conscious dogs.

In the present study, a radioimmunoassay for oxytocin determinations is presented. In addition, we investigated whether the elevation of insulin, VIP and gastrin levels demonstrated to occur in response to suckling in lactating dogs may be induced by released oxytocin. Therefore, oxytocin was infused i.v. into conscious dogs in amounts calculated to give rise to plasma levels observed during physiological circumstances. Plasma levels of oxytocin, insulin, VIP (vasoactive intestinal polypeptide) and gastrin were measured by radioimmunoassay. When oxytocin was infused at a rate of 0.22 and 2.2 nmol kg-1 h-1, plasma oxytocin levels rose to 176 +/- 25 fmol ml-1 and to 1490 +/- 400 fmol ml-1, respectively, 10 min after the infusions were started. Plasma insulin levels rose in response to oxytocin administered at a rate of 0.22 and 2.2 nmol kg-1 h-1. A peak was recorded within 5 min of oxytocin infusion, that is, before maximal oxytocin levels were recorded, and basal levels were reached within about 20 min. The VIP levels rose slightly following infusion of oxytocin at 0.22 nmol kg-1 h-1, but a clear-cut response that lasted for 60 min was observed following infusion of oxytocin at the highest dose. In contrast, gastrin levels were not influenced by the oxytocin infusions. Suckling in dogs is followed by rapidly occurring short-lasting elevations of oxytocin levels in plasma which amount to 50-100 fmol ml-1. Since insulin and VIP were released by oxytocin when administered in amounts that give rise to plasma levels close to those levels, it is suggested that the secretion of insulin and VIP that occurs in response to suckling in lactating dogs may in part be caused by previously released oxytocin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

[The clinical value of sequential renal scans with 131 iodo-hipuran and renal perfusion with 99mtc compounds using computer analysis (author's transl)].

Two methods of sequential scintigraphy are considered critically: a) Quantitative computer evaluation of nephrograms obtained by a gamma camera using 131Iodo-Hipuran. b) Quantitative flow studies of the kidneys after bolus injections of 99mTc preparations. Statistical evaluation of data from 171 patients examined by both methods has shown that the isotope nephrogram is not sufficiently sensitive for diagnostic purposes. Isotope nephrography combined with estimations of effective renal plasma flow on each side separately is of value to the urological surgeon by providing important information regarding severe degrees of renal functional impairment. Perfusion measurements, using a gamma camera and 99mTc preparations, are a promising survey method for the diagnosis of renal artery stenosis. (Much of this work is contained in a dissertation by C. Knick).

Diagnosis, Computer-Assisted↗