Search PubMed⌕ Search

Biomedical subjects

S Smitz

Publications and source records attributed to S Smitz.

32 records · Page 2Linked to original sources
PubMed1984

Dose-response relationship between plasma oxytocin and cortisol and adrenocorticotropin concentrations during oxytocin infusion in normal men.

We previously demonstrated that acute injection of a pharmacological dose of oxytocin (2 IU) in humans decreased the concentrations of ACTH and cortisol, a neuroendocrine action opposite that of vasopressin. In the present work the effect of continuous infusion of lower doses of oxytocin was tested. Plasma oxytocin was also measured using an oxytocin RIA to study the dose-response relation. Infusion of oxytocin (8 mIU/min for 30 min) resulted in a plasma oxytocin level of 9.9 +/- 1.4 (+/- SD) muIU/ml and induced a decrease in the plasma concentration of ACTH in three of four normal subjects. Infusion of oxytocin at the rate of 16 mIU/ml for 30 min resulted in plasma oxytocin level of 17.7 +/- 1.6 muIU/ml and decreases in plasma ACTH and cortisol concentrations in all six subjects tested. Increasing the oxytocin dose from 32 to 64 and 128 mIU/min for three additional 30-min periods induced more pronounced decreases in plasma ACTH and cortisol. In each subject, there was a highly significant inverse relationship between plasma oxytocin, and ACTH and cortisol (r = -0.85 to -0.99). During saline infusion, a significant inverse relationship with a 10-min lag period between plasma oxytocin and ACTH (r = -0.55) was found in only one of six subjects. These data demonstrate that infusion of exogenous oxytocin leading to plasma levels approximately 10 times higher than normal induced consistent decreases in corticotropic function. Because the oxytocin concentration in portal blood is approximately 300 times higher than that in peripheral blood, it is likely that the inhibitory action of oxytocin on ACTH secretion is of physiological significance.

Adrenocorticotropic Hormone↗
PubMed1984

[Circulating vasopressin (ADH) during immersion of short duration].

During immersion in sitting position to the neck of 9 normal adult males, no change has been observed in the concentration of circulating ADH (1.91 +/- 0.58 versus 2.08 +/- 0.76 pg.ml-1) after 45 minutes. In the same period, diuresis is significantly increased (1.26 +/- 0.14 versus 3.9 +/- 1.19 ml.min-1).

Adult↗
PubMed1981

[Hypodypsia and selective dysfunction of osmoreceptors in the hypernatremia syndrome].

We studied a patient with the rare syndrome of chronic hypernatremia associated with a frontal expansive process. The pituitary function was evaluated during dynamic tests bearing on radioimmunoassay of serum neurophysins levels. A test of water restrictionloading was performed during which urine appeared diluted (190-200 mOsm/kg) while the degree of serum osmolality was high (310-317 mOsm/kg). An hemodynamic stimulation resulted in a significant increase in serum neurophysins (from 3.5 +/- 0.3 to 5.5 +/- 0.2 ng/ml). After one intravenous injection of 2 mg nicotine, vomiting was observed, followed by a sharp rising of serum neurophysins levels (from 3.2 +/- 0.5 to 10.6 +/- 0.2 ng/ml). During hypertonic saline infusion, serum osmolality increased from 270 to 310 mOsm/kg, while neurophysins showed no significant change. Such results evidence a selective impairment of the hypothalamic-neurohypophyseal response to osmotic stimuli, with intact mechanisms of non-osmotic stimulation. In this patient, natremia was brought back to normal values by adequate water supply.

Adolescent↗
PubMedDate not supplied

Penetration of DGAVP (Org 5667) across the blood-brain barrier in human subjects.

To assess the penetration of desglycinamide-arginine-vasopressin (DGAVP, Org 5667) to the central nervous system, levels of DGAVP were measured in the lumbar CSF after peripheral administration. DGAVP (2 mg) was administered intranasally to 37 patients and CSF samples were collected from these patients 5 to 240 minutes later. Detectable levels of DGAVP in CSF could be found 5 minutes after administration, but levels declined rapidly during the next 90 minutes. The DGAVP levels in CSF correlated with plasma levels of DGAVP (r=0.586, p less than 0.001). According to these results, DGAVP may gain access to the central nervous system and may induce central effects.

Administration, Intranasal↗
PubMedDate not supplied

[The care of the older person with diabetes mellitus].

The care of the older adult with diabetes mellitus should be individualized, taking into consideration the patient's functional status and coexistent illnesses, as well as his or her preferences and life expectancy. The overall goal of care is to improve both the clinical status and the quality of life. Components of care are education, glycaemic control, cardiovascular risk factor management, eye and foot care and management of nephropathy and geriatric syndromes. A team approach is recommended. Glycaemic control and cardiovascular risk factor modification can reduce the risk of complications and improve the quality of life. However, the risk of severe or fatal hypoglycaemia associated with the use of anti-hyperglycaemic drugs increases with age and comorbidity. Targets for glycaemic control and HbA1c should be realistic, dynamic and tailored to the characteristics of each individual patient. Since cardiovascular complications are the main cause of morbidity and mortality, managing cardiovascular risk factors is mandatory. Hypertension should be treated gradually. The therapeutic approach comprises lifestyle modifications and anti-hyperglycaemic drugs. Older persons should be evaluated regularly to assess and review the medication being used. An appropriate physical activity, especially walking can forestall functional decline and decrease all-causes and cardiovascular mortality. Identifying and managing such geriatric syndromes as dehydration, cognitive dysfunction and depression may improve the quality of life.

Aged↗
PubMedDate not supplied

[Chronic hypernatremia. A study of plasma neurophysins and action of morphine].

The hypothalamo-neurohypophyseal function was evaluated in a patient with the chronic hypernatremia syndrome. By dosing plasmatic neurophysins, a selective loss of the osmoreceptor function was demonstrated. Morphine administration was followed by a reduction of the diuresis and a slight elevation of plasmatic neurophysins. The mechanism of morphine action is discussed.

Chronic Disease↗
PubMedDate not supplied

[Hypothalamoneuropituitary activation during vasodilatator perfusion in normal individuals (author's transl)].

The hypothalamo-neurohypophyseal function has been tested in 9 normal individuals (age 22 - 50; 2 women and 7 men) in the course of a vasodilatator perfusion (sodium nitroprussiate) in standardized conditions. Vasopressin-neurophysin (hNPI), oxytocin-neurophysin (hNPII) and total immunoreactive neurophysins (IRN) have been assayed. Our preliminary results show a clear-cut increase of hNPI and IRN when the decrease of the mean blood-pressure exceeds 20 +/- 10% (15 - 33). There is only a weak, if any, increase of hNPII. There is a highly significant relationship (r : 0.90, p less than 0.01) between maximal increment of IRN and maximal increment of heart frequency suggesting a similar way of activation. Vasodilatator perfusion could be, in the future, a reliable test for hypothalamo-neuropituitary function although it's reproducibility has still to be deeper investigated.

Adult↗