Increased OB gene expression leads to elevated plasma leptin concentrations in patients with chronic primary hyperinsulinemia.

Leptin, a hormone secreted by adipocytes, decreases food intake and increases energy expenditure. The role of insulin in the regulation of leptin secretion is poorly understood and is still a topic of debate. Insulin increases leptin mRNA synthesis in rodents, but in humans, the available data are discordant. To investigate the role of chronic hyperinsulinemia in the regulation of plasma leptin concentrations, we studied 13 patients with surgically confirmed insulinoma before and after tumor removal, along with 15 healthy control subjects matched for sex, age, and BMI. Immunoreactive plasma leptin levels were measured by radioimmunoassay; leptin mRNA levels were also determined by reverse transcription-competitive polymerase chain reaction in a subgroup of six patients with insulinoma and six control subjects. All determinations were made with subjects in the fasting state. Plasma leptin concentrations correlated positively with leptin mRNA levels (r = 0.880, P < 0.001). Leptin levels, both plasma protein and mRNA, were significantly higher in the insulinoma patients than in the control subjects (plasma protein: 17.5 +/- 3.6 vs. 2.9 +/- 0.4 ng/ml, respectively, P < 0.001; mRNA: 0.98 +/- 0.33 vs. 0.19 +/- 0.064 amol/microg RNA, respectively, P < 0.05), and they correlated positively with fasting plasma insulin levels in the patients with insulinoma (plasma protein: r = 0.686, P < 0.01; mRNA: 0.796, P < 0.05). Finally, removal of the insulin-secreting tumor was followed by the normalization of plasma leptin levels. In summary, in patients with insulinoma, 1) plasma leptin levels and leptin mRNA are elevated; 2) a direct relationship exists between leptin, both circulating protein and mRNA, and insulin concentrations; and 3) plasma leptin returns to normal levels after tumor removal. These data, therefore, support a role for insulin in the chronic regulation of leptin gene expression.

Two polyclonal antisera detect different AGE epitopes in human plasma samples.

Advanced glycation end products (AGEs), involved in the pathogenesis of diabetic complications, comprise a series of related chemical structures which might possess dissimilar immunogenic characteristics. In this study the levels of AGE in plasma samples from normal subjects (N=41) and diabetic patients (N=44) were measured by ELISA using two polyclonal antisera (named CF5 and CF199, respectively, and immunologically characterized) raised using two different immunogens and immunization techniques. Age levels were significantly higher in diabetic than in normal plasma samples (P<0.0001) with both antisera. However, CF199 detected higher AGE levels than CF5 both in normal (P<0.0001) and diabetic (P<0.005) samples. Pre-incubation with AGE-bovine serum albumin (BSA) caused the loss of most the reactivity of both antisera. Pre-incubation with carboxy-methyl-lysine-BSA (an oxidation-derived AGE) induced the loss of nearly all CF5 reactivity while CF199 retained a significant amount of activity against AGE antigens. Moreover, CF5 lost over 90% of its reactivity against BSA incubated with high glucose under non-oxidative conditions, suggesting its recognition of mainly oxidation-derived AGE epitopes. The different AGE levels measured by the two antisera suggests, therefore, that one single antiserum is unable to recognize all the various AGE epitopes which might be present, at any time, in tissues and body fluids in health and disease.

Effect of age and relation to mortality on serial changes of vasoactive intestinal peptide in acute myocardial infarction.

Plasma levels of vasoactive intestinal peptide increase early after acute myocardial infarction (AMI) and are significantly higher during the first 2 weeks of AMI in survivors and younger patients (<60 years) than in those who died and in older (>60 years) patients. Data suggest that vasoactive intestinal peptide is involved in neuroendocrine activation occurring in AMI and could be regarded as a marker of the course of AMI.

Expression of the two insulin receptor isoforms is not altered in the skeletal muscle and liver of diabetic rats.

Alternative splicing of the 36-base pair exon 11 of the human insulin receptor (IR) gene and of the corresponding domain of the rat IR gene results in the synthesis of two IR isoforms with distinct functional characteristics. Altered expression of these IR isoforms has been previously demonstrated in the skeletal muscle of patients with non-insulin-dependent diabetes mellitus (NIDDM); however, this observation was not confirmed by other studies and is still a matter of debate. To assess whether the reported altered isoform expression is due to the secondary metabolic derangement of diabetes, we examined alternative splicing of IR mRNAs (IR36+ and IR36-, corresponding to human Ex11+ and Ex11-) in the skeletal muscle and liver of 6-hour fasting 90% pancreatectomized insulin-resistant diabetic and control Sprague-Dawley rats, using the reverse transcriptase-polymerase chain reaction (PCR) technique. Both diabetic and control rats showed the same pattern of IR mRNA expression: the liver exclusively expressed IR36+ mRNA, whereas only IR36- mRNA was detected in muscle. In conclusion, diabetes mellitus per se does not alter the expression of IR isoforms in the liver and skeletal muscle, and therefore, at least in this animal model of NIDDM, impaired insulin action develops independently from a relative increase in IR36+ mRNA expression in skeletal muscle.

[Molecular analysis of the gene of steroidogenic acute regulatory protein (StAR) in adrenal incidentaloma]. / Analisi molecolare del gene della proteina di regolazione acuta della steroidogenesi (StAR) negli incidentalomi surrenalici.

The steroidogenic acute regulatory protein (StAR) plays an essential role in steroidogenesis, facilitating cholesterol entry into the inner compartment of mitochondria. Mutations (either transitions or transversions) of StAR gene have been described as a cause of lethal forms of congenital lipoid adrenal hyperplasia. Adrenal incidentalomas are frequently discovered during radiologic examinations performed in patients with diagnosis for other diagnostic problems. Enzymatic defects along the steroidogenetic cascade are observed with high frequency in these patients. Aim of the present study was to asses the involvement of alteration of the StAR gene in incidentally discovered adrenal masses (incidentalomas). The mutational analysis of 32 incidentalomas demonstrated a "missense" mutation in exon five of the gene in one of the tumors analysed. This is the first evidence of an alteration of the StAR gene in adrenal incidentalomas.

IGF-1 levels in diabetic pregnant women and their infants.

Plasma IGF-1 was measured in 38 diabetic pregnant women (DPW) and in 12 non diabetic pregnant women (NDPW) during the 1st, 2nd and 3rd trimester of pregnancy. IGF-1 was measured in the cord blood of 24 infants of diabetic mothers (IDDM) and IGF-1 in 11 infants of non diabetic mothers (NIDDM). A progressive and significant (p < 0.0001) increase of IGF-1 values was found throughout the pregnancy both in DPW and NDPW IGF-1 (149 +/- 18 ng/ml vs 181 +/- 14 ng/ml, 184 +/- 17 ng/ml vs 232 +/- 25 ng/ml, 279 +/- 20 ng/ml vs 325 +/- 17 ng/ml). Furthermore IGF-1 decreased significantly soon after delivery in both groups of women. In type 1 diabetic pregnant women IGF-1 values were significantly lower than the controlled non diabetic patients. IGF-1 in the cord blood was significantly higher in IDDM than in NIDDM 86 +/- 7 ng/ml and 62 +/- 7 ng/ml respectively (p < 0.03). In addition, DPW plasma levels IGF-1 were positively correlated with the weight of the placenta (r = 0.233, p < 0.03) and negatively correlated with the diabetes duration (r = 0.412, p < 0.05). No correlations were found between IGF-1 cord blood concentrations and gestational age, birth weight and length, but there was a significant correlation with weight percentile (r = 0.846, p < 0.001). No correlation was found between maternal IGF-1 plasma levels and other parameters like insulin need, weight gain, metabolic control and time of delivery.

[Neuroendocrine activation in acute myocardial infarction: state of the art and preliminary results on intestinal vasoactive peptide]. / Attivazione neuroendocrina nell'infarto acuto del miocardio: stato dell'arte e risultati preliminari sul peptide vasoattivo intestinale.

Acute myocardial infarction (AMI) is known to be associated with a complex neuroendocrine activation, especially concerning sympathetic and renin-angiotensin systems, cortisol, atrial natriuretic peptide and endothelin. Results of our study show that the vasoactive intestinal peptide (VIP), also, is early involved in the neuroendocrine activation occurring in AMI. Plasma concentration of VIP, significantly increased in AMI patients within 6 hours after the onset of chest pain, soon decreased and remained below than normal along the first week. At the 14th day of the AMI, plasma levels of VIP returned into the normal range. A significant increase of VIP plasma concentration is detectable in the first hours of AMI in survived as compared with died patients. The phenomenon seems to be a suitable process to provide an endogenous support to the ischemic heart and to counteract the negative effects of other neuroendocrine activated factors.

Levels of advanced glycosylation end-products (AGE) in sera of pregnant diabetic women: comparison between type 1, type 2 and gestational diabetes mellitus.

The chronic hyperglycemia can lead to an increase of the advanced glycosylation end-products (AGE) levels on proteins and macromolecules. Abnormal levels of AGE in several tissues has been associated with the pathogenesis of late diabetic complications. In diabetic pregnant women, high AGE levels might influence the delicate maternal-fetal balance and therefore alter the pregnancy outcome. In this preliminary study, we have measured the AGE in sera of 44 diabetic women in two trimester. Sixteen sera from non diabetic pregnant women have been used as controls. The AGE have been analyzed by means of an ELISA method with an antiserum anti-RNAse-AGE, produced in the Laboratory of Clinical Biochemistry of the Istituto Superiore di Sanità. Diabetic patients type 1 and type 2, in good metabolic control, showed normal AGE levels at both trimester. Patients with gestational diabetes showed significantly high serum AGE levels (p < 0.05). A more extended study will give better insight on the association between AGE levels and a physiopathology of diabetic pregnancy.

[Vasoactive intestinal peptide in heart failure]. / Il peptide vasoattivo intestinale nello scompenso cardiaco.

BACKGROUND: The aim of our study was to investigate the pathophysiological role of the vasoactive intestinal peptide (VIP), a vasodilating neuropeptide with positive inotropic and chronotropic properties, in heart failure. METHODS: The study was carried out in 35 patients with heart failure due to dilated cardiomyopathy, who underwent a peripheral venous blood sample for radioimmunoassay of VIP within the first in-hospital day. RESULTS: The plasma concentration of VIP: 1) is not higher than normal in the whole group of patients with heart failure; 2) is higher in younger than in elderly healthy subjects but does not significantly change in relation to age in heart disease patients; 3) is higher in elderly (> 60 years) but not in younger (< 60 years) patients compared to healthy subjects of the same age; 4) is higher in NYHA functional class 2 than in NYHA functional class > 2 groups and in normal subjects; 5) is not correlated with echocardiographic parameters; 6) does not significantly change with respect to the etiology of dilated cardiomyopathy. CONCLUSIONS: The plasma concentration of VIP in heart failure is conditioned by some epidemiological and clinical variables. Unlike the healthy group, differences are not detectable with respect to the age of patients; thus, in elderly heart disease subjects the neuropeptide productive potentiality is preserved. Taking into account the physiological properties of VIP, its plasma increase in the initial phase of heart failure can be reasonably regarded as a further mechanism to restore the compromised hemodynamic balance. Its decrease, related to worse clinical conditions, could be due to a progressive depletion from the pre-synaptic nerve endings and to a deficiency in the neurogenic productive capacity of the molecule.

A comparison of methods for the detection of hepatitis B virus surface antigen (HBsAg).

Our aim was to check the relative sensitivity of the various commercial kits available on the Italian market for the detection of hepatitis B virus surface antigen (HBsAg) in its two subtypes ay and ad. To this end, panels from different producers were compared by parallel sensitivity assays of several kits. It was found that the kits revealed different sensitivities depending on the panel used, and that sensitivity curves were not parallel. Given the lack of uniformity of response in the various panels currently available, we preferred to use two panels prepared at the Istituto Superiore di Sanità, one for each of the aforementioned subtypes. These HBsAg serial-concentration preparations were used to measure the sensitivity of the different kits on the basis of distinct methodological principles, i.e. RIA, ELISA and RPHA. These are currently considered the most sensitive methodologies and are used for kits classified as belonging to the 3rd generation. For each kit we used the procedure indicated by its manufacturer as being the most sensitive. For some of the kits we adopted all procedures in parallel recommended by respective manufacturers for different conditions of use. Sensitivity was found to be a function of lot, kit, methodology and procedure used. For the RIA and ELISA kits, we also used a modified method in parallel with the normal procedures. This method consisted in presaturating the solid phase in a solution of bovine albumin serum and was generally shown to increase the sensitivity of the kit adopted. For the majority of the kits examined, as well as the direct tests, a confirmatory test was also used, i.e. a specific inhibition test to verify the positivity revealed. In this way an increase in the sensitivity of the sample was also obtained.

Survey on controls for the presence of HBsAg in products based on hemoderivatives.

In Italy, Health Ministry provisions prohibit the marketing of products based on hemoderivatives unless they have first been controlled for the presence of HBsAg by means of radioimmunoassay. The present survey considers certificates submitted by Pharmaceutical Companies to the Health Department for permission to market their hemoderivative-based products. The results of the survey are discussed, and compared with the data obtained by the AA. in official control analyses, so as to arrive at some conclusion as to the applicability of currently employed RIA methods to HBsAg detection in hemoderivatives.

Postnatal Stress in Mice: Effects on Body Fat, Plasma Lipids, Glucose and Insulin.

Mice pups were exposed to stressful stimuli everyday during the first 3 weeks of life. Body weight, food intake and spontaneous locomotor activity, triglycerides, cholesterol, phospholipids, glucose and insulin basal levels, as well as epididymal fat pad weight and its cell volume were measured in stressed and control animals. Results indicated that postnatal stressful manipulations induced an increase in body weight, epididymal fat pad weight and its cell volume, as well as in insulin, glucose, cholesterol and triglycerides plasma levels, at 4 months of age. No significant changes in food consumption, locomotor activity and phospholipids plasma levels were found. Present data suggest that early stressful manipulations may induce residual effects on lipid and glucid metabolism.

Relative contribution of glycogenolysis and gluconeogenesis to hepatic glucose production in control and diabetic rats. A re-examination in the presence of euglycaemia.

Several studies have suggested that, in non-insulin-dependent diabetes mellitus, augmented gluconeogenesis is responsible for increased endogenous glucose production (EGP) and in the end determines fasting hyperglycaemia. However, human and animal studies have been conducted by comparing euglycaemic control subjects to hyperglycaemic diabetic probands. We measured EGP and hepatic gluconeogenesis comparing control and diabetic rats in the fasting state (with diabetic animals in hyperglycaemia), re-examining them in the presence of identical euglycaemia (with diabetic rats made acutely euglycaemic through i. v. phloridzin) or during a hyperinsulinaemic clamp. All rats were infused with [3-3H]-glucose and [U-14C]-lactate; the ratio between 14C-uridine-diphosphoglucose (reflecting 14C-glucose 6-phosphate) and 2 14C-phosphoenolpyruvate specific activities (both purified by high performance liquid chromatography from liver) measured hepatic gluconeogenesis. In diabetic animals, although overall EGP ( approximately 19.5 mg x kg[-1] x min[-1]) remained unaffected by experimental euglycaemia, the contribution of glycogenolysis largely increased (from 5.4 to 11.7 mg x kg(-1) min(-1), hyper- vs euglycaemia) while gluconeogenesis decreased (from 14.0 to 8.1 mg x kg(-1) x min[-1]); both were responsible for the augmented EGP (control rats, EGP: 12.7 mg x kg(-1) x min(-1); gluconeogenesis: 5.9 mg x kg(-1) x min(-1); glycogenolysis: 6.7 mg x kg[-1] x min[-1]). Finally, during insulin clamp, gluconeogenesis and glycogenolysis were similarly decreased, and both contributed to the hepatic insulin-resistance of diabetic animals. We conclude that, in this model of non-insulin-dependent diabetes, augmented gluconeogenesis is not primarily responsible for fasting hyperglycaemia and hepatic insulin resistance. Finally, failure to accurately match the experimental conditions in which diabetic and control humans or animals are compared affects gluconeogenesis, overestimating its role in determining hyperglycaemia.

[The physiopathological role and prognostic value of the vasoactive intestinal peptide in acute myocardial infarct]. / Ruolo fisiopatologico e valore prognostico del peptide vasoattivo intestinale nell'infarto acuto del miocardio.

Aim of our study was to investigate the pathophysiological role of vasoactive intestinal peptide (VIP) in the neuroendocrine activation occurring in acute myocardial infarction (AMI). Plasma VIP concentration has been assayed in 30 patients with AMI, 22 males and 8 females, aged 41-82 years, without other important diseases. VIP plasma values, assayed on admission to the Coronary Care Unit, within 4-6 hours after the onset of chest pain, everyday for the first week and on day 14, were significantly higher in survivors and in patients aged < 60 years. VIP plasma concentration was not statistically correlated with CPK and CPK-MB. VIP seems to play a pathophysiological role in the neuroendocrine activation occurring in AMI. Low VIP plasma levels are associated with an unfavorable short-term prognosis. Moreover, it appears that VIP secretion is negatively influenced by aging.