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Biomedical subjects

N Surico

Publications and source records attributed to N Surico.

At least 37 records · Page 2Linked to original sources
PubMed1999

The effect of 17beta-oestradiol on regional blood flow in anaesthetized pigs.

1. The present study was designed to investigate the effects of 17beta-oestradiol on the mesenteric, renal, iliac and coronary circulations and to determine the mechanisms involved. 2. In pigs anaesthetized with sodium pentobarbitone, changes in blood flow in the superior mesenteric, left renal, left external iliac and left circumflex coronary arteries caused by intravenous infusion of 17beta-oestradiol at constant heart rate and arterial pressure were assessed using electromagnetic flowmeters. 3. In eight pigs, infusion of 2 microg h-1 of the hormone caused an increase in renal, iliac and coronary blood flow without affecting mesenteric blood flow, left ventricular dP/dtmax (rate of change of left ventricular systolic pressure) and filling pressures of the heart. In four pigs, these vasodilator effects were enhanced by graded increases in the dose of the hormone between 1, 2 and 3 microg h-1; the highest dose also caused an increase in mesenteric blood flow. 4. In five pigs, blockade of muscarinic cholinoceptors and adrenoceptors with the intravenous administration of atropine, propranolol and phentolamine did not affect the vasodilator responses caused by infusion of 2 microg h-1 of 17beta-oestradiol. 5. The increases in renal, iliac and coronary blood flow caused by infusion of 2 microg h-1 of 17beta-oestradiol were prevented, respectively, by the injection of Nomega-nitro-L-arginine methyl ester (L-NAME) into the renal artery (five pigs), the iliac artery (five pigs) or the coronary artery (five pigs). In five pigs, all responses were prevented by injection of L-NAME into all three arteries. In two pigs, injection of L-NAME into the mesenteric, renal, iliac and coronary arteries abolished the vasodilator responses to the infusion of 3 microg h-1 of 17beta-oestradiol. 6. The present study shows that intravenous infusion of 2 microg h-1 of 17beta-oestradiol primarily dilated renal, iliac and coronary circulations and that a higher dose of the hormone also caused vasodilatation in the mesenteric vascular bed. The mechanism of these responses was shown to be nitric oxide dependent.

Animals↗
PubMed1999

The role of beta 2-adrenergic vascular receptors in the peripheral vasodilation caused by 17 beta-estradiol in anesthetized pigs.

It has been previously shown in anesthetized pigs that intravenous infusion of 2 microg/h of 17beta-estradiol primarily dilated renal, iliac and coronary circulations, while higher doses of the hormone were required to cause vasodilation also in the mesenteric vascular bed. In the same experimental model, a tonic beta2-adrenoceptor mediated vasodilation, which could be argued to attenuate the vasodilator effect of 17beta-estradiol, has been described. The present study was planned to investigate the role of beta2-adrenergic receptors in the hemodynamic responses of renal and mesenteric vascular beds to 17beta-estradiol. Changes in flow caused by intravenous infusion of 2 microg/h of the hormone at constant heart rate and aortic blood pressure in the left renal and superior mesenteric arteries were assessed using electromagnetic flowmeters. In six pigs, infusion of 17beta-estradiol caused an increase in renal blood flow, which averaged 12.1% of the control values, without affecting mesenteric blood flow. In the same pigs, after hemodynamic variables had returned to the baseline values, blockade of beta2-adrenergic receptors with butoxamine caused an increase in aortic blood pressure and an increase in renal and mesenteric resistance. The subsequent infusion of 17beta-estradiol elicited increases in renal and mesenteric blood flow which respectively averaged 19.6% and 12.8%. Therefore, the present study in anesthetized pigs have shown that the vasodilator responses of the renal and mesenteric circulations to 17beta-estradiol were attenuated and even masked by a tonic beta2-adrenoceptor mediated vasodilation. This indicates that some vasodilator effects elicited by normally used replacement doses of the hormone may not be apparent.

Adrenergic beta-Antagonists↗
PubMed1999

Biohumoral parameters and bone mineral content in the identification of high risk subjects for postmenopausal osteoporosis.

BACKGROUND: The aim of this study was to evaluate the possibility of identifying women with a high risk of postmenopausal osteoporosis by using computerised bone mineral analysis (CBMA) associated with markers of bone turnover in order to provide a valid and reliable screening test. METHODS: A total of 925 patients were evaluated, 252 of whom had already undergone a preliminary densitometric test six months earlier and were diagnosed as fast bone losers. 225 of them (89%) also showed altered bone turnover markers. CBMA was negative in the remaining 673 patients but 13 patients showed altered bone turnover markers and three of the latter then showed a positive CBMA 18 months later. The 673 patients who, after six months of study, were not fast bone losers were monitored over time. RESULTS: It emerges from these results that fast bone losers are characterised by higher levels of hydroxyprolinuria and calcium, lower levels of oestrone and estradiol, and reduced body weight compared to healthy subjects. CONCLUSIONS: This simplified method enabled 79% of the fast bone losers to be identified, whereas densitometry identified 87.5% of the high-risk subjects. The main advantage of our simplified method compared to the measurement of bone mineral content is that it identifies the majority of fast bone losers in the initial postmenopausal period, before a substantial reduction in BMC has taken place.

Bone and Bones↗
PubMed1998

The effect of distension of the uterus on plasma renin activity (PRA) in anaesthetized pigs.

It has recently been shown that distension of the uterus in anaesthetized pigs causes reflex haemodynamic responses through efferent sympathetic mechanisms. The present study was undertaken to determine whether these mechanisms include activation of the renin-angiotensin system. The same methods were used in 14 pigs which were anaesthetized with alpha-chloralose and artificially ventilated. Balloons positioned within the uterus were distended for periods of 30 min by injecting 20 ml of warm Ringer solution. The responses of arterial blood pressure and heart rate were respectively prevented by blockade of alpha-adrenergic receptors with phentolamine and atrial pacing. Changes in plasma renin activity (PRA) were assessed during the last minute of distension by radioimmunoassay of angiotensin I. In each of 10 pigs, distension of the uterus (mean uterine transmural pressure of 17 mmHg) caused an increase in PRA in the absence of changes of interfering haemodynamic variables. In the remaining four pigs, this response was graded by step increments of the distension. The increase in PRA caused by uterine distension was abolished by bilateral section of the renal nerves (five pigs) or by blockade of beta-adrenergic receptors with propranolol. The present study showed that distension of the uterus in anaesthetized pigs primarily caused a reflex increase in PRA. This reflex response was mediated by renal nerves and involved beta-adrenergic receptors.

Adrenergic alpha-Antagonists↗
PubMed1998

[Biochemical markers of bone remodeling in the prevention of postmenopausal osteoporosis].

Normal bone mass is one of the principal factors in the prevention of osteoporosis for women in advanced age. Therefore, it is necessary to have efficacious serum and urinary markers available to screen the bone development and the bone resorption. Even if we are also far from identifying an ideal marker, the measurement of some substances such as pyridinoline (Pyr) and deoxypyridinoline (D-Pyr) seems to be a first progress for efficacious and rather simple techniques.

Aged↗
PubMed1997

Changes in regional blood flow in response to distension of the uterus in anaesthetised pigs.

The present study was undertaken in anaesthetised pigs to determine the primary reflex effects of distension of the uterus on the peripheral circulation. Experiments were performed in seven pigs anaesthetised with alpha-chloralose and artificially ventilated. Blood flow in the superior mesenteric, left renal and left external iliac arteries was assessed using electromagnetic flowmeters. Distension of the uterus was performed whilst preventing changes in heart rate and aortic blood pressure by injecting 20 ml of warm Ringer solution in a balloon positioned within the viscus (mean transmural pressure of about 18 mmHg). In each pig, distension of the uterus caused decreases in all measured blood flows. In four pigs, these decreases were graded by step increments of distension. In the seven pigs, the responses of decrease in mesenteric, renal and iliac blood flows were not affected by blockade of beta-adrenergic receptors with propranolol, but were abolished by the subsequent blockade of alpha-adrenergic receptors with phentolamine. The present study showed that distension of the uterus in anaesthetised pigs primarily caused reflex vasoconstriction in the mesenteric, renal and iliac vascular beds. This reflex response was mediated by sympathetic mechanisms which involved alpha vascular adrenergic receptors.

Adrenergic beta-Antagonists↗
PubMed1997

Reflex haemodynamic responses caused by distension of the uterus in anaesthetized pigs.

The present study was undertaken in anaesthetized pigs to determine whether distension of the uterus reflexly affects the aortic blood pressure, heart rate, left ventricular inotropic state and the coronary circulation. Experiments were performed in 17 pigs anaesthetized with alpha-chloralose and artificially ventilated. Coronary blood flow was measured with an electromagnetic flowmeter positioned around the origin of the left circumflex coronary artery. The uterus was distended by injecting 20 ml warm Ringer solution into a balloon positioned within the uterus (mean transmural pressure of about 17 mmHg). Distension of the uterus without controlling any haemodynamic variable caused an increase in aortic blood pressure. When this response was prevented, an increase in heart rate was obtained in each animal. When the heart rate and blood pressure responses were prevented, the distension did not cause significant changes in the maximum rate of change of left ventricular pressure, but always caused a decrease in mean coronary blood flow. In five pigs, the increase in heart rate and the decrease in mean coronary blood flow were graded by step increments of distension. In six pigs, the haemodynamic responses to distension of the uterus were not affected by the administration of atropine. In 12 pigs, which included the six given atropine, the increase in heart rate was abolished by the administration of propranolol and the increase in aortic blood pressure and the decrease in mean coronary blood flow were abolished by the subsequent administration of phentolamine. In the remaining five pigs, the haemodynamic responses caused by uterine distension were abolished by the administration of bretylium tosylate. The present study showed that distension of the uterus in anaesthetized pigs primarily caused reflex increases in heart rate and aortic blood pressure and coronary vasoconstriction. These reflex responses were mediated by efferent sympathetic mechanisms.

Afferent Pathways↗
PubMed1997

Difference of LH and FSH secretory characteristics and degree of concordance between postmenopausal and aging women.

OBJECTIVE: Several neuroendocrine changes occur at menopause and the present study aimed to verify whether the episodic release and the degree of concordance of LH and FSH differs between early and late postmenopausal women. METHODS: Postmenopausal (n = 32) women were enrolled and subdivided in two groups according to the menopausal age: group A (n = 22), patients with more than 2 but less than 5 years from the occurrence of menopause; group B (n = 10), patients with more than 15 years from the occurrence of menopause. All subjects underwent a pulsatility study (4 h, sampling every 10 min) to assess LH and FSH secretory characteristics and their degree of concordance. RESULTS: Mean +/- S.E.M. LH and FSH plasma levels were lower in older women than in postmenopausal women (P < 0.01). The secretory pattern was pulsatile for both LH and FSH and their pulse amplitudes were lower in aged women (P < 0.01). No significant difference was observed in terms of pulse frequency between the two groups. LH and FSH pulses were co-secreted in early postmenopausal women while such a concordance was lost in older women. CONCLUSIONS: Late postmenopause is characterized by the reduction of the amplitude of gonadotropin pulses in comparison to women in early postmenopause, reflecting changes of both GnRH secretion and/or pituitary responsiveness to GnRH. The age-related loss of concordance between LH and FSH pulses discloses the existence of a hidden FSH stimulating system, which drives FSH episodic release independently and more promptly than GnRH.

Aging↗
PubMed1997

[Estrogen-progestin contraception and biohumoral response of new markers of the atheroma risk. Behavior of lipoprotein(a) and apolipoproteins A and B].

A homogeneous group of 45 patients, aged between 19 and 37 years was considered in relationship to metabolic response during oral contraceptive use. A free endocrinological-metabolic pathology control group, formed by 30 patients, aged between 22 and 35, who were not treated with any therapy in the six months before, was also considered. We also considered any other factors like smoking, height, and weight in all women of our study. Study-trial was comprehensive of a 12 months follow-up, with some periods of study at 0, +6, +12 months. Metabolic responses of lipoprotein(a) and apolipoprotein A and B during the different follow-up steps were determined. Total and fractionated cholesterol and triglycerides were also determined. Positive correlations were shown between Lipo(a) and Apo B and also between total cholesterol and LDL. Negative correlations were shown between Lipo(a) vs HDL and Apo A. Lipoprotein(a) was determined by the ELISA technique and turbidimetric technique. The aim of our study was to verify the importance of the new markers of atheroma risk; even if the oral estrogen-progestin contraception little interferes with this biohumoral marker synthesis, it improves atheroma risk protection through the lipidic metabolism complexity.

Adult↗
PubMed1997

Ultrasound diagnostic criteria in breast disease.

The Kasumi-Kamio parameters (margins, peripheral echoes, internal echoes, posterior echoes, lateral shadow cones) and the ratio between the longitudinal and transverse diameter of the breast lump form the basis for a list of standardised diagnostic criteria on which to base an analysis of breast disease that assesses the specificity and sensitivity of ultrasonography as a valid, reliable initial step in the diagnosis of breast tumours. The study was based on a series of 129 tumour cases and produced correct diagnosis in 89.28% of benign, 83.33% of malignant cases.

Breast Neoplasms↗
PubMed1995

Naltrexone administration modulates the neuroendocrine control of luteinizing hormone secretion in hypothalamic amenorrhoea.

Because endogenous opioids have been considered to be deeply involved as a causal factor of hypothalamic amenorrhoea, this study was designed to evaluate the efficacy of the administration of naltrexone, an antagonist of opioid receptors, on luteinizing hormone (LH) secretion in patients with hypothalamic amenorrhoea. A total of 30 patients with hypothalamic amenorrhoea were studied. Patients were divided into two groups: group A, hypogonadotrophic (n = 15), and group B, normogonadotrophic (n = 15). All patients were administered naltrexone at a dose of 50 mg/ day per os for 6 months. A third group of 10 amenorrhoeic patients was treated with placebo per os with the same schedule. All patients were evaluated for LH spontaneous pulsatile release in baseline conditions and after 3 and 6 months of treatment. Plasma gonadal steroid concentrations increased significantly in all patients after 3 months of naltrexone therapy, but only hypogonadotrophic patients showed a sharp increase in both LH plasma concentrations and LH pulse amplitude within the first 3 months of treatment which remained unchanged until the sixth month of treatment. Plasma follicle stimulating hormone concentrations did not change significantly in any patient. Menstrual bleeding occurred within 90 days of the beginning of treatment in 24 out of the 30 patients. Patients treated with placebo did not show a significant change in gonadotrophin and gonadal steroid plasma concentrations. The results of our study support the efficacy of naltrexone administration on neuroendocrine pathways controlling LH secretion in patients with hypothalamic amenorrhoea.

Amenorrhea↗
PubMed1995

Distribution of integrins and extracellular matrix proteins in vulvar squamous cell carcinomas.

We report the topography of integrins and some basement membrane zone (BMZ) proteins in normal vulvar skin and in seven cases of vulvar squamous carcinoma (VSC). In vulvar epidermis integrin chains alpha 2, alpha 3 and beta 1 lined the lateral surface of basal cells, while the heterodimer alpha 6 beta 4 was detected only at their basal domain. The location of alpha 6 beta 4 exactly matched BMZ identified by kalinin, laminin and collagen type IV. In VSC this pattern was subverted since both beta 1 integrins and alpha 6 beta 4 became pericellular. In particular, alpha 6 beta 4 lost its coherence with the residual organization of BMZ. In fact, BMZ components displayed their normal pattern were this was preserved, and so were fibronectin and tenascin in the stroma underlying the tumor. Furthermore, alpha 5 beta 1, the prototype fibronectin receptor that is not normally exposed in vulvar epidermal cells, became detectable pericellularly in VSC tumor cells. Alteration of integrin polarized topography appears to be typical of VSC cells as well as of other tumor epidermal cells. This alteration may be easily shown by immunohistochemistry on routinely collected frozen biopsies. It may then represent a tool for the early diagnosis of VSC that provides a quick and easy complement of traditional histology.

Aged↗
PubMed1994

The duration of prolactin secretory bursts from the pituitary is independent from both prolactin and gonadal steroid plasma levels in women and in men.

The intrinsic secretory characteristics of prolactin (PRL) have been investigated using newly developed algorhythms for instantaneous secretory rate (ISR) computation. PRL secretory rate, its intrinsic pulsatile characteristics and their possible dependance from gonadal steroids were investigated in five groups of subjects: a) 11 women during the follicular and luteal phase of the same menstrual cycle; b) 5 healthy postmenopausal women; c) 6 women affected by functional hyperprolactinemia; d) 5 normal men; e) 4 agonadal subjects before and during testosterone replacement therapy. All subjects underwent a 6 hours pulsatility study, from 08:00 to 14:00, sampling every 10 minutes. PRL plasma concentrations were determined using a RIA system and the presence of PRL secretory pulses was evaluated with program DETECT, both on plasma time series and after ISR computation. A distinct PRL episodic release was observed in all groups (follicular phase: 5.5 +/- 0.5, luteal phase: 6.5 +/- 0.6, postmenopause: 5 +/- 1, hyperprolactinemic women: 4.2 +/- 0.8, men: 4.8 +/- 0.4, agonadal before testosterone: 6 +/- 1, agonadal during testosterone administration: 5.3 +/- 0.3 peaks/6h), but mainly the computation of ISR allowed to demonstrate that the duration of the lactotropes secretory events was constant in all groups studied. PRL secretory bursts duration ranged between 23.1 +/- 1.8 and 25.4 +/- 2.5 minutes independently both on PRL or on sex steroid plasma levels. In conclusion, the present report shows that in different physiological conditions the intrinsic secretory bursts from lactotropes are constant in duration independently from the functional state, sex and the steroid hormone levels.

Adult↗
PubMed1994

Intrinsic secretory characteristics of luteinizing hormone and prolactin episodic release during pubertal development.

The intrinsic characteristics of LH and prolactin (PRL) episodic secretion were evaluated in a group of 18 children (8M and 10F). The children were divided into two groups according to the Tanner stage: Group A (Tanner < or = 1, N = 7, 3M and 4F, 6-10 years of age) and group B (Tanner 2-3, N = 11, 5M and 6F, 9-11 years of age). A pulsatility study of 4 h, sampling every 10 min, was carried out in all children. LH and PRL plasma levels were assayed by IFMA and RIA respectively. LH and PRL secretory episodes were then identified on plasma determinations using the program DETECT. Instantaneous secretory rates (ISR) were then computed for both LH and PRL using the specific algorithm within the DETECT program. Plasma LH levels were different between the two groups of children. Group A children showed undetectable LH plasma levels (below the minimal detectable dose of 0.1 mIU/ml), while group B demonstrated LH plasma levels in the normal range of values for age and sexual development (1.5 +/- 0.3 mIU/ml, mean +/- SEM). LH pulse frequency for group B was 3.2 +/- 0.4 peaks/4 h. No significant differences in mean plasma PRL levels, pulse frequency and pulse amplitude were observed between the two groups of children. Computation of ISR for LH (group B only) and PRL (both groups) identified the intrinsic episodic characteristics of the two hormones. No significant differences in LH and PRL pulse frequencies were observed when comparing the results estimated on ISR with those estimated on plasma concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Episodic release of prolactin in women with weight loss-related amenorrhea.

Amenorrhea associated with weight loss is characterized by several neuroendocrine aberrations. The aim of the present study was to define the characteristics of episodic secretion of prolactin in women with weight loss-related amenorrhea. To evaluate whether hypoestrogenism was responsible for the changes in prolactin secretion in amenorrheic women, the pulsatile secretory pattern was also studied during hormone replacement therapy (HRT). Fifteen patients were studied by blood sampling every 10 min for 8 h. Four normally cycling women were studied as a reference group, during both the midfollicular and midluteal phases. Mean plasma prolactin levels and pulse amplitude were lower in amenorrheic patients than in controls. The prolactin pulse frequency was higher than that in controls during the follicular phase, but lower than controls during the luteal phase of the menstrual cycle. During HRT, mean plasma prolactin levels significantly increased, pulse frequency decreased and pulse amplitude significantly increased both during estradiol and estradiol plus medroxyprogesterone acetate administration. In conclusion, in amenorrhea associated with weight loss the chronobiological organization of prolactin secretion is deranged, both as a result of a neuroendocrine alteration and as a result of low plasma levels of gonadal steroids.

Amenorrhea↗