Docking-based analysis and modeling of the activity of bile acids and their synthetic analogues on large conductance Ca2+ activated K channels in smooth muscle cells.

OBJECTIVE: The objective of this study was to perform docking-based analysis of bile acid binding on the protein complex of channels and to derive neural network that predicts the influence of bile acids and their synthetic analogues on the activity of BK(Ca) channels in smooth muscle cells based on descriptors for bile acids and their synthetic analogues and on their already published activities using patch-clamp techniques. MATERIALS AND METHODS: Ligands for molecular docking were optimized using computer routine for minimization of energy by using the force field MMFF94 via Chem3D 15.0 and ligands and protein channel complex were prepared in AutoDockTools 1.5.6. AutoDock Vina 4.0 software was used for blind docking; processing and verification of the obtained results was performed via Discovery Studio 4.0. Neural network was derived using descriptors for bile acids and their synthetic analogues and their already published activities on calcium-activated K+ channels in smooth muscle cells (ChemDraw Professional 15.0, Dragon 6 software). RESULTS: Molecular docking was performed for: lithocholic acid, deoxycholic acid, 5ß-cholanoic acid, 3ß-hydroxi-5ß-cholanoic acid, henodeoxycholic acid, ursocholic acid and α-muricholic acid. Neural network model Multiple layer perceptron is derived, having 0.9259 training performances and 0.3673 test performances, training error 0.0073 and test error 0,1607. Model was tested for henodeoxycholic, ursocholic and α-muricholic acid, and internal validation of the model is performed. CONCLUSIONS: Molecular docking suggested that the pharmacophore for maximizing the activity of BK(Ca) channels in the steroid skeleton of bile acids is the C3 quasi-axial α-OH group and the C24 carboxyl function. Derived neural network model successfully predicted activities of tested bile acids on Ca2+ activated K+ channels in smooth muscle cells.

The influence of CYP2C8*3 on carbamazepine serum concentration in epileptic pediatric patients.

The aim of the present study was to investigate the distribution of CYP2C8 variants *3 and *5, as well as their effect on carbamazepine pharmacokinetic properties, in 40 epileptic pediatric patients on carbamazepine treatment. Genotyping was conducted using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and allele-specific (AS)-PCR methods, and steady-state carbamazepine plasma concentrations were determined by high performance liquid chromatography (HPLC). The CYP2C8 *3 and *5 polymorphisms were found at frequencies of 17.5 and 0.0%, respectively. After dose adjustment, there was a difference in daily dose in CYP2C8*3 carriers compared to non carriers [mean ± standard deviation (SD): 14.19 ± 5.39 vs. 15.46 ± 4.35 mg/kg; p = 0.5]. Dose-normalized serum concentration of carbamazepine was higher in CYP2C8*3 (mean ± SD: 0.54 ± 0.18 vs. 0.43 ± 0.11 mg/mL, p = 0.04), and the observed correlation between weight-adjusted carbamazepine dose and carbamazepine concentration after dose adjustment was significant only in CYP2C8*3 non carriers (r = 0.52, p = 0.002). However, the population pharmacokinetic analysis failed to demonstrate any significant effect of CYP2C8 *3 polymorphism on carbamazepine clearance [CL L/h = 0.215 + 0.0696*SEX+ 0.000183*DD]. The results indicated that the CYP2C8*3 polymorphism might not be of clinical importance for epilepsy treatment in pediatric populations.

Clopidogrel cessation triggers aspirin rebound in patients with coronary stent.

WHAT IS KNOWN AND OBJECTIVE: Premature discontinuation of clopidogrel in patients undergoing percutaneous coronary intervention is a significant risk factor for thrombotic adverse outcomes. However, recent studies indicate that even discontinuation of long-term use of clopidogrel may be associated with multiple adverse outcomes, that is, rebound phenomenon whose mechanism is not definitely clear. The aim of the study was to examine the effect of clopidogrel withdrawal in those on combined aspirin and clopidogrel therapy. METHODS: This prospective, multicenter study enrolled 200 patients who underwent coronary stent implantation and were on dual antiplatelet therapy (100 mg aspirin + 75 mg clopidogrel) 1 year after the stent placement. In all patients, we measured the platelet aggregation, by multiplate electrode aggregometry, using two agonists [adenosine diphosphate with PGE1 (ADPHS) and arachidonic acid (ASPI)] two times: on the day of cessation of clopidogrel and 90 days after clopidogrel was stopped. RESULTS AND DISCUSSION: Following clopidogrel discontinuation, we registered an increase in ASPI values (P < 0·001), linear correlation between changes in ASPI and ADPHS values (P = 0·009) and significant difference in the values of ASPI first quartile of ADPHS compared with the other three (P < 0·001, P = 0·016, P < 0·001, I vs. II, I vs. III and I vs. IV quartile of ADPHS, respectively). WHAT IS NEW AND CONCLUSION: Our findings show that cessation of clopidogrel causes loss of antiplatelet synergism with aspirin, leading to a weakening of the response to aspirin, which may be one explanation for the rebound after the clopidogrel cessation.

The Brief Repeatable Battery: psychometrics and normative values with age, education and gender corrections in a Serbian population.

Cognitive impairment is present in up to 65 % of multiple sclerosis (MS) patients. The Brief Repeatable Battery of neuropsychological tests (BRB) is one of the most used neuropsychological tools for cognitive assessment in MS. However, relative lack of normative data limits its application in research and clinical practice. In order to obtain normative data for a Serbian population, we administered the BRB version A to 140 healthy subjects and assessed the influence of demographic factors such as gender, age, and education on the tests' scores. We also calculated corrections for these factors. Higher education was associated with better performance on all the tests. Age influenced all the tests, except the word list generation, higher age being associated with worse performance on all other tests. Women performed worse on the paced auditory serial addition test 2, no other gender differences were observed. Our data obtained for the Serbian population could further improve use of the BRB in clinical practice and for the research purposes, establishing cognitive evaluation as a part of standard neurological examination of MS patients.

Adenosine stress protocols for nuclear cardiology imaging.

UNLABELLED: The treadmill test combined with myocardial perfusion imaging (MPI) is a commonly used technique in the assessment of coronary artery disease (CAD). However, there is a group of patients who may not be able to undergo the treadmill test. Pharmacologic stress testing is increasingly utilized for stress perfusion imaging and currently accounts for nearly 40% of all nuclear stress testing [8]. The aim of this study was the introduction of adenosine stress protocols in our nuclear laboratory, and the following, recording and comparing of the frequency and severity of side-effects. METHODS: We performed two kinds of adenosine stress protocols on 186 patients who underwent MPI with radiotracer 99mTc-sestamibi: 1st: 47 patients underwent AdenoSCAN abbreviated protocol IV. adenosin 140microg/kg/min for 3 minutes; 2nd: AdenoEX combined with low level 50W bicycle exercise in 139 patients. We followed and compared side-effects (minor and major events) between AdenoSCAN and AdenoEX protocol, and established an adequate time for imaging of both protocols. RESULTS: Compared with AdenoSCAN, AdenoEX protocol was tolerated by all patients; it reduced all side-effects and improved image quality. Using AdenoEX protocol we found that the heart-to-liver ratio was significantly better, and we established a time of imaging of 15 minutes after stress, compared to the AdenoSCAN time of imaging which was a minimum of 45 minutes after stress. CONCLUSION: This study gives advatages to AdenoEX protocol, because it had fewer side-effects, improved patients' tolerance, improved image quality, and enhanced efficiency and throughput given the opportunity for earlier imaging.

Determination of culprit lesion in patients undergoing elective percutaneous coronary intervention by myocardial perfusion imaging.

UNLABELLED: The aim of this study was to determine and localize culprit lesion by myocardial perfusion imaging (MPI) in cases of angiographically detected coronary narrowing >or= 75% of at least one coronary artery. MATERIAL AND METHODS: One hundred and thirty-two (132) patients with angiographically detected significant coronary narrowing (>or= 75% luminal stenosis of at least one major coronary artery) were studied. All the patients submitted MPI (99m)Tc-MIBI, with pharmacologic dipyridamole stress protocol with concomitant low level bicycle exercise 50W (DipyEX). We measured relative uptake (99m)Tc-MIBI for each myocardial segment using short-axis myocardial tomogram study. A 5-point scoring system was used to assess the difference between uptake degree in stress and rest studies for the same segments, and we created two indices: Sum reversibility score (SRS), Index of sum reversibility score (ISRS). RESULTS: A total of 396 vascular territories (2244 segments) were analyzed before elective percutaneous coronary intervention (ePCI). Overall sensitivity, specificity and accuracy using SRS were 90.2%, 87.5%, and 89.4%, with a positive predictive value of 94.1%. Overall sensitivity, specificity, and accuracy using ISRS were 94.4%, 90.6%, 93.2% and the positive predictive value was 95.7%. CONCLUSION: DipyEX MPI with the two indices created, SRS and ISRS, significantly improves sensitivity, specificity and accuracy in the determination and localization of culprit lesions in patients undergoing elective PCI.

Diagnostic value of biohumoral markers of necrosis and inflammation in patients with right ventricular myocardial infarction.

INTRODUCTION/AIM: Patients with right ventricular myocardial infarction (RVMI) and patients with left ventricular myocardial infarction (LVMI) of the anterior wall with ST-elevation (STEMI), due to the profundity and volume of the necrosis, tend to have a more severe and more complicated clinical outcome as well as a higher mortality level compared to patients with myocardial infarction of inferoposterior localization in the left ventricle (IPILK), without the right ventricle being overtaken. C-Reactive protein (CRP) is a sensitive and reliable indicator of acute inflammation and is in good correlation with creatin kinasis (CK) or the enzymes which indicate necrosis markers in acute myocardial infarction (AIM). Because of this, a common biohumoral answer is of greater importance and more reliable both diagnostically and prognostically; it signifies a more severe and more complicated clinical outcome, especially on the rupture of the myocardium. The main goal of this study was to compare the maximum values of enzymes and CRP in patients with RVMI and LVMI who had first STEMI and who were in the acute phase treated with percutaneous transluminal coronary angioplasty (PTCA). METHODS: During a six-year period (2000-05), in the Clinic for Urgent Internal Medicine at the Military Medical Academy, a total of 74 patients included in a prospective study were divided into two groups. The first group consisted of patients with RMI 19 (25.67%), and the second group of patients with LMI 55 (74.33%). The patients in both groups received a percutaneous coronary intervention (PCI), if they had been admitted in the first 4 hrs from the beginning of the chest pain, and if there were no contraindications. All the others received thrombolitic therapy, and a "rescue" PCI if needed, in the next 24-48 hours. The risk factors, clinical outcome, necrosis and inflammation biomarkers (enzymes and CRP), coronary status, restenosis of stent, and intra-hospital mortality rate in the first month, as well as a long term prognosis over a period of one year, were analysed. RESULTS: The average age of the patients in the group with RVMI 19 (7 m + 12 f) was 66.1 +/- 11y, and in the group with LVMI 55 (45 m + 10 f) 59.6 +/-13y, with a statistical trend which indicated that the patients with RVMI were older (66.1 +/- 11y vs. 59.6 +/- 13y, p < 0.061) and that women dominated (63.1% vs. 18.8%, p < 0.001). No statistical differences were found between the two groups of patients concerning the length and the appearance of the chest pain before admission to the hospital and the beginning of the PCI treatment, as well as risk factors such as smoking, cholesterol or diabetes. Of the total of 74 patients with the first STEMI as a primary manifestation of a coronary disease, we performed a primary PCI on 58 (78.37%), and a "rescue" PCI on 16 (21.63%) after the thrombolitic therapy during the 24-48h after admission. We had no cases of death either during the primary or the delayed PCI, or in the next 24h following the intervention. During the hospital phase of treatment, in the group with RMI the causes of death were the rupture of the free wall of the right ventricle (1), acute pancreatitis (1), ARDS and hypostatic pneumonia (1), cerebrovascular insult (1). During the following year, one more patient died due to reinfarction of the anterior localization. In the group with LMI, during the hospital phase of treatment 5 (9.09%) patients died: reinfarction (2), rupture of the left ventricle (1), respiratory insufficiency and severe hypostatic pneumonia (1), cerebrovascular insult (1). During the following year, 4 more patients died, sudden death (2), ischemic dilatative cardiomyopathy (2). The total mortality rate over a one-year period of observation in the group with LMI was 9 (16.3%), and in the group with RMI 5 (26.3%). Radionuclide ventriculography (RNV) was performed in the acute phase of myocardial infarction from 7-14 days after PCI and after 6 months in both groups as an independent indicator of the ejection fraction (EF) of both ventricles. The given results show that a statistically proven significant difference exists in the recovery of the right ventricle in acute phase RMI (49.1 +/- 7.9 vs. 35.4 +/- 10, p< 0.001), as well as after 6 months (49.2 +/- 9.7 vs. 38.3 +/- 11.2, p < 0.010) in patients with RMI. CONCLUSION: Primary PCI should be done whenever it is possible with all patients who have a great volume and depth of necrosis, especially if that is the first manifestation of a coronary disease and the first acute STEMI, as were all of our patients in both groups. Our results show that older patients with RMI, and dominantly women, have a more severe and more complicated clinical outcome in the acute phase of RMI compared to patients with LMI of the anterior wall. In the longer prognosis of this case, they have a quicker and a more complete recovery of the right ventricle due to which they have a better immediate and long term prognosis, but demand careful overseeing and energetic treatment in the acute phase of the myocardial infarction, especially considering that their treatment is often specific compared to patients with an infarction of the left ventricle.

In vivo modulation of the distribution of thymocyte subsets by female sex steroid hormones.

This study examined the effects of the principal ovarian steroids, 17 beta-estradiol (E) and progesterone (P), on the thymic structure and on the intrathymic development of T-cells. Adult female rats were ovariectomized (OVX) and treated for 14 days with physiological doses of either E or P; controls received an equivalent volume of vehicle. Ovariectomy produced a marked increase (vs. sham-operated controls) in thymus weight, which was associated with an increase in the volume and cellularity of both the medulla and cortex. Treatment of OVX rats with E reduced the thymic weight to value, which was significantly lower than that of sham-operated controls decreasing the volume of cortex below level in sham-OVX rats, and reversing the effect of ovariectomy on the volume of medulla. P only prevented the increases in thymus weight and cortical volume induced by OVX. However, unlike E, it had no discernable effect on the medullary volume. E treatment reduced the cellularity of the cortex and medulla to values, which were lower than those of sham-OVX rats, while P only reversed the effects of OVX on the cellularity of both the compartments. Ovariectomy also had a profound effect on the thymocyte profile, increasing the proportion of CD4+8+TCR alpha beta- cells and producing a corresponding decrease in the relative proportions of all TCR alpha beta high cell subsets. The decrease in the latter was opposed by treatment with E or P. However, the sensitivity of the less mature cells (except CD4-8-TCR alpha beta-, the percentage of which was reduced by both hormones) to the two hormones differed. E reduced the relative proportion of CD4-8+TCR alpha beta-, CD4-8+TCR alpha beta low and CD4+8+TCR alpha beta- cells, while P increased the percentage of CD4-8+TCR alpha beta low cells. The results suggest that E and P affect both the lymphoid and nonlymphoid compartments of the thymus, and that while P increases the volume of the nonlymphoid component of the medulla, E has the opposite effect. The finding that ovariectomy decreased while E and P increased the relative proportion of the most mature thymocytes, which include CD4-8-TCR alpha beta high cells that are believed to harbour potentially autoreactive cell clones, is particularly interesting and may relate to the high propensity of autoimmune diseases in females.

In vivo modulation of the splenocyte yield and composition by female sex steroid hormones.

The study was designed to shed more light on the controversial role of the two main ovarian steroid hormones (i.e. estradiol and progesterone) in shaping the size and phenotypic characteristics of the splenic lymphocyte pool. For this purpose ovariectomized adult rats (OVX) were treated for 14 subsequent days with either estradiol or progesterone (to attain physiological concentrations of the hormones). Afterwards, the splenocyte yield, and overall number of splenocytes bearing TCR alpha beta receptor, CD4 and CD8 coreceptor were evaluated. Fourteen-day-long ovarian hormone deprivation produced an increase in the splenic weight and splenocyte yield (on the account of a rise in the number of TCR alpha beta- cells), although the number of TCR alpha beta+ cells was reduced as a result of a decrease in the size of the CD4+ cell subpopulation. Replacement of either estradiol or progesterone prevented the increase in splenic weight and reduced the splenocyte yield to values significantly lower than that in sham-OVX rats. Both the treatments completely abolished the effect of ovariectomy on the size of TCR alpha beta- cell population, but had differential effects on that of TCR alpha beta+ cell population; estradiol did not affect its size, while progesterone caused a reduction on the account of a decrease in the numbers of both CD4+ and CD8+ cells. The results suggest that: a) estradiol and progesterone have similar effects on the size of the splenic B cell population and that replacement of either estradiol or progesterone can prevent the effects of ovariectomy on the size of this population and b) estradiol does not affect while progesterone reduces the size of splenic T cell population. Thus, replacement of none of them is able to compensate the removal of gonads.

[Clinical study of administration of abciximab--a monoclonal antibody to platelet glycoprotein IIb/IIIa in percutaneous intracoronary interventions]. / Klinicka studija o primeni monoklonskog antitela protiv IIb/IIIa glikoproteina trombocita--abciksimaba kod bolesnika sa perkutanom intrakoronarnom intervencijom.

During the last 10 years a new group of drugs was developed--platelet glycoprotein IIb/IIIa blockers that is nowadays largely and efficiently used as for the prevention of percutaneous coronary intervention complications as well as in the treatment of acute coronary syndromes. In the period February-June 2000--19 patients (18 males, 1 female, of average age 53.3 years) were administered Abciximab in the bolus dose of 10 mg immediately before the intervention and afterwards 10 mg by 12-hour infusion. All patients received aspirin and ticlopidine hydrochloride if the stent was introduced and heparin by the standard protocol. Elective intervention was done in 17 patients (non-Q infarction in 3 patients, unstable angina pectoris in 5 patients, postinfarction angina pectoris in 2 patients, acute myocardial infarction at least 1 month before the intervention in 6 patients and 1 patient with myocardiopathy) and in 2 patients the intervention was performed during the myocardial infarction. In 15 patients (79%) intracoronary stent was introduced and in 5 patients (21%) the intervention was performed on 2 arteries. Maximal immediate effect of the dilatation was achieved in 18 patients (94.7%). In the first 60 days of the follow-up 1 patient (5%) died of some other disease, and in no patients symptomatic myocardial ischemia was found. No adverse effects were observed.

GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults.

BACKGROUND: The diagnosis of growth hormone (GH) deficiency in adults is based on provocative testing of GH secretion. The insulin tolerance test (ITT), currently the favoured test for this diagnosis, has been criticised for poor reproducibility and inconvenience. Since the combined administration of GH-releasing hormone (GHRH) plus GH-releasing peptide-6 (GHRP-6) is the most potent stimulus of GH secretion, we did a multicentre study comparing GH peaks elicited by ITT with those elicited by the GHRH/GHRP-6 test in healthy controls and GH-deficient individuals (cases). METHODS: 125 adult patients with organic pituitary disease and 125 healthy individuals were studied. All cases and controls were given GHRH 1 microg per kg bodyweight intravenously plus GHRP-6 1 microg per kg intravenously at 0 min and blood samples were obtained during a subsequent 120 min period. 27 controls and all cases had an ITT. Inclusion criteria were severe GH deficiency--ie, a GH peak after ITT of < or = 3 microg/L. Results of the GHRH/GHRP-6 test were analysed by receiver-operating characteristic curve methodology. FINDINGS: GH peaks seen after the GHRH/GHRP-6 test did not result in any side-effects and were not affected by age, sex, amount of adipose tissue, or by the GH assay system used. The GH mean peak after the GHRH/GHRP-6 test was 59.2 microg/L (SD 2.2) for controls and 4.1 microg/L (0.3) for cases, whereas after ITT the mean peak was 14.3 microg/L (1.7) and 0.5 microg/L (0.06), respectively. The differential peak responses of controls and cases was greater (p<0.001), for GHRH/GHRP-6 test than for ITT. When individually analysed GH peaks were a continuum, from 139.0 microg/L to 0.01 microg/L, with a cut-off point of 15.0 microg/L. The GHRH/GHRP-6 test performed well under the ROC curve analysis. For clinical utility, it is then proposed that values > or = 20.00 microg/L be considered normal and < or = 10.00 microg/L as GH deficient. INTERPRETATION: The GHRH/GHRP-6 test is a convenient, safe and reliable test for adult GH deficiency and is not confounded by clinical factors known to alter GH secretory patterns. An evoked GH concentration of > or = 15.0 microg/L accurately distinguishes between healthy and GH-deficient adults.

Lipid peroxidation intensity and lipid status parameters in the estimation of the severity of ischemic heart disease.

Atherosclerotic changes on the coronary arteries are the basis of the ischemic heart disease. It is assumed that the initial changes in this process occur as a consequence of the lipid peroxidation in the vessel wall. We estimated this process through the level of malondialdehyde (MDA) in the serum of 86 patients in whom selective coronary angiography was done for the suspected ischemic heart disease. According to the number of the stenotic coronary arteries (stenosis greater than 50%), we divided the patients into four groups: the control group with normal coronary angiography finding, simple, double or triple vessel coronary disease. In all the patients we also estimated the other parameters of the lipid status (cholesterol, triglycerides, LDL, HDL, Apo-AI, Apo B) and atherogenic indices Apo-AI/Apo B, LDL/HDL and HDL/total cholesterol. No significant changes were observed in the lipid parameters between the control and experimental group. However, mean MDA level in the whole experimental group was 3.89 mumol/L, 3.93 mumol/L in triple vessel coronary disease, 3.83 mumol/L in double vessel and 3.92 mumol/L in single vessel disease group. The difference between all the experimental and the control group was highly significant (p < 0.001). We concluded that the level of MDA--lipid peroxidation index had the better correlation with the disease status than the other parameters of lipid status and the sensitive atherogenic indices.

Pituitary adenomas secreting large amounts of prolactin may give false low values in immunoradiometric assays. The hook effect.

Immunoradiometric assay (IRMA) for serum prolactin (PRL) measurement can give falsely low values, leading to unnecessary surgery in patients with prolactinomas. We studied clinical and biochemical features of patients with pituitary macroprolactinomas in whom plasma PRL levels had been underestimated due to the so-called "high dose PRL hook effect". This phenomenon was observed in four (14.2%) out of 28 patients with pituitary macroadenomas (13 macroadenomas) and 15 non-functioning macroadenomas) reffer during one-year period. Undiluted median (range) PRL levels were 11.3 (3.0-48.7), 983.9 (194.4-1959.4), and 96.9 (66.6-147.7) micrograms/l in patients with non-functioning macroadenomas, macroprolactinomas and the hook effect adenomas, respectively. In all patients assay was performed after serum dilution, and only in patients with the hook effect the median PRL levels increased significantly to 5795.0 (2097.2-12722.2) micrograms/l. The mean age at diagnosis was 38 +/- 6.5, 45 +/- 6, and 53 +/- 3 yr, for the patients with the hook effect, macroprolactinoma and non-functioning adenoma, respectively. Males were predominant (75%) in the hook effect adenoma group. Patients with the hook effect macroprolactinomas were all treated successfully with dopamine agonists, and all patients had significant shrinkage of the tumor mass (more than 50% shrinkage). In conclusion, this study suggests that patients with high dose PRL hook effect are generally younger, more frequently males with very large pituitary adenomas (grade III-IV according to Hardy). It is necessary, whenever performing IRMA for serum prolactin measurement, to dilute samples routinely (1:1 and 1:10 dilutions) in every patient with pituitary tumor.

Growth hormone secretion elicited by GHRH, GHRP-6 or GHRH plus GHRP-6 in patients with microprolactinoma and macroprolactinoma before and after bromocriptine therapy.

OBJECTIVE: Growth hormone-releasing peptides (GHRPs) are potent GH releasers which act at both pituitary and hypothalamic levels through specific G-protein coupled receptors, recently cloned. A synergistic effect from the simultaneous administration of GHRH + GHRP-6 on GH release is observed in normal subjects, while it is absent in patients with hypothalamo-pituitary disconnection. We studied the effects of GHRH, GHRP-6 and both secretagogues on GH release in patients harbouring pituitary tumours that may be reduced in size by medical treatment. DESIGN: Analysis of peak GH response to GHRH, GHRP-6 and GHRH plus GHRP-6 in patients with micro- and macroprolactinomas. Integrated GH response over 2 hours calculated as AUG-GH mU/l x 120 min. Analysis of delta PRL above the basal level in response to the same GH releasers. PATIENTS: Eleven patients with macroprolactinomas aged 41.2 +/- 4.8 years (range 24-75), nine patients with microprolactinomas aged 31.5 +/- 3.4 (range 22-53) and 13 healthy subjects aged 42.1 +/- 4.7 years (range 22-64) were studied. Prolactinoma patients were then treated with bromocriptine (15-20 mg orally) for 6-24 months. Tests were repeated when there was evidence of tumour shrinkage and normalized plasma prolactin concentrations. RESULTS: Peak GH response before treatment in macroprolactinoma patients was 4.9 +/- 0.9 mu/l after GHRH, 8 +/- 4 mU/l after GHRP-6 and 18 +/- 5 mU/l after GHRH + GHRP-6. Synergism was absent. AUC were 390 +/- 90; 500 +/- 100 and 1100 +/- 300 mU/l x 120 min respectively. These values were all significantly different (P < 0.05) from normal subjects and patients with microprolactinomas with peak GH 16.8 +/- 0.9 mU/l after GHRH; 43 +/- 6 mU/l after GHRP-6 and 130 +/- 10 mU/l after GHRH + GHRP-6. AUC-GH was 1200 +/- 400 after GHRH, 2200 +/- 400 after GHRP-6 and 9000 +/- 1000 mU/l x 120 min after GHRH + GHRP-6. As in normal subjects, synergism was preserved in patients with microprolactinoma (P > 0.05). After treatment with bromocriptine peak GH in patients with macroprolactinoma was 8 +/- 4 mU/l after GHRH, 22 +/- 5 mU/l after GHRP-6 and 70 +/- 20 mU/l after GHRH + GHRP-6. AUC-GH was 800 +/- 300, 1100 +/- 300 and 3500 +/- 800 mU/l x 120 min, respectively. The response of GH after GHRP-6 and GHRH + GHRP-6 improved significantly (P < 0.05) in treated patients with macroprolactinoma. There was no significant change in GH response in microprolactinoma patients after treatment with bromocriptine. Peak GH after GHRH was 30 +/- 20 mU/l, after GHRP-6 it was 75 +/- 8 mU/l and after GHRH + GHRP-6 it was 200 +/- 30 mU/l. AUC-GH was 1500 +/- 700 after GHRH, 4500 +/- 500 after GHRP-6 and 15,100 +/- 600 mU/l x 120 min. Delta prolactin after GHRP-6 did not change before and after bromocriptine treatment in patients with macroprolactinoma or microprolactinoma. CONCLUSION: GH release after GHRP-6 or GHRH + GHRP-6 is fully preserved in patients with microprolactinomas and does not differ before and after treatment with bromocriptine. Patients with macroprolactinoma have blunted responses of GH after GHRH and GHRP-6 and synergism is severely compromised. GH responsiveness to and synergistic interaction between GHRH and GHRP-6 recovers after shrinkage of macroprolactinoma with bromocriptine. Prolactin release stimulated by intravenous administration of GHRP-6 in healthy subjects was not seen in patients with micro- or macroprolactinomas.

Serum leptin and insulin concentrations in patients with insulinoma before and after surgery.

Inferential studies suggest that circulating insulin concentrations positively regulate leptin secretion by adipocytes. In humans, however, insulin requires prolonged periods of time, and relatively artificial set-ups before a relationship with leptin can be observed. In the present work, serum leptin concentrations were measured in five patients with insulinoma before and one month after surgery and in five control subjects matched by sex and body mass index (BMI). The control subjects presented a mean serum leptin concentration of 6.7+/-1.5 microg/l and a BMI of 24.9+/-1.1. The mean serum leptin concentration in patients with insulinoma was 11.8+/-3.1 microg/l (P < 0.05 vs controls), with a BMI of 26.3+/-1.9. After surgery, there was a non-significant reduction in BMI (25.8+/-1.7), and a clear reduction in serum leptin concentration (5.6+/-2.4 microg/l, P < 0.05 vs pre surgical values and no difference vs control subjects). The fasting area under the curve (AUC) of insulin concentration (in mU/l per 120 min) before surgery was 14421+/-4981 and after surgery was 1306-/+171 (P < 0.05). Before surgery, serum leptin concentrations significantly correlated with BMI (r = 0.71) and AUC of insulin (r = 0.82), a correlation that was lost after surgery. In conclusion, serum leptin concentrations are significantly elevated in patients with chronically high insulin levels due to insulinoma. After surgical treatment and normalization of insulin values, leptin levels return to normal.