Daniela Vivenza

Circulating ghrelin levels as function of gender, pubertal status and adiposity in childhood

Ghrelin, a natural GH secretagogue, exerts remarkable endocrine and non-endocrine activities such as orexigenic effect and modulation of the endocrine and metabolic response to variations in energy balance. Ghrelin levels have been reported to be negatively associated to insulin secretion, enhanced in anorexia and reduced in obesity. Ghrelin levels in childhood have never been evaluated. We measured morning ghrelin levels after overnight fasting in 29 healthy lean children (NC) and in 36 obese children (OBC). The results were compared with those recorded twice in 3 different sessions in healthy lean adults (NA). In NA ghrelin levels showed good within-subject reproducibility without gender-related differences. Ghrelin levels in NC [(median; 25°–75° centile): 426.0; 183.0–618.0 pg/ml] were similar to those in NA (380.5; 257.7–551.7 pg/ml). Ghrelin levels in OBC (229.5; 162.5–339.5 pg/ml) were lower (p<0.03) than in NC (426.0; 183.0–618.0 pg/ml). Both in NC and in OBC, ghrelin levels were independent of gender and pubertal status. In all children, ghrelin levels were negatively associated (p<0.05) to weight excess (r=−0.24), insulin (r=−0.28) and IGF-I (r=−0.4) levels. In conclusion, these findings demonstrate that morning ghrelin levels after overnight fasting show good within-subject reproducibility, and are similar in both sexes and do not vary from childhood to adulthood. In childhood, circulating ghrelin levels are reduced in obese subjects being negatively correlated to overweight and insulin secretion.

Ghrelin secretion is inhibited by glucose load and insulin-induced hypoglycaemia but unaffected by glucagon and arginine in humans.

objective  Circulating ghrelin levels are increased by fasting and decreased by feeding, glucose load, insulin and somatostatin. Whether hyperglycaemia and insulin directly inhibit ghrelin secretion still remains matter of debate. The aim of the present study was therefore to investigate further the regulatory effects of glucose and insulin on ghrelin secretion.

Subclinical hypothyroidism in children and adolescents: a wide range of clinical, biochemical, and genetic factors involved.

OBJECTIVE The aim of the study was to examine clinical characteristics, biochemical parameters, and TSH-R gene variations in children and adolescents with subclinical hypothyroidism (SH) in order to evaluate their pattern of distribution in SH. PATIENTS We enrolled 88 patients, each having at least two TSH measurements above the upper limit of the reference range with normal free thyroid hormones and negative thyroid autoantibodies. MAIN OUTCOME MEASURES Clinical characteristics included height, weight, family history of thyroid diseases, thyroid volume, and echogenicity at ultrasonography. Biochemical parameters included TSH, free thyroid hormones, thyroid autoantibodies, and adjusted daily urinary iodine excretion (UIE). Genetic variations in the TSH-R gene were assessed. RESULTS The prevalence of overweight/obesity, positive family history of thyroid diseases, and thyroid hypoechogenicity was 28.4, 45.5, and 22.7%, respectively. Median TSH was higher in overweight/obese patients than in normal-weight ones (7.4 vs. 5.7 muIU/ml; P = 0.04) and in overweight/obese patients with hypoechogenicity than in those with normal ultrasound pattern (8.5 vs. 6.8 muIU/ml; P = 0.04). Adjusted daily UIE was lower in subjects without than in those with a positive family history of thyroid diseases (81 vs. 120 mug/d; P = 0.001). The prevalence of a positive family history of thyroid diseases was 1.9-fold higher in patients with nonsynonymous mutations in the TSH-R gene than in patients without any mutation (80 vs. 42%; P = 0.03). A novel mutation at position 1559 in exon 10 (W520X) was detected in one child. CONCLUSIONS Overweight/obesity, thyroid hypoechogenicity, and nonsynonymous mutations in the TSH-R gene are characterizing features of a large portion of SH children.

Oral glucose load inhibits circulating ghrelin levels to the same extent in normal and obese children

Objective  The presence of both the GH secretagogue (GHS) receptor and ghrelin in the pancreas indicates an involvement of this hormone in glucose metabolism. Ghrelin secretion is increased by fasting and energy restriction, decreased by food intake, glucose load, insulin and somatostatin in normal adults; however, food intake is not able to inhibit circulating ghrelin levels in children, suggesting that the profile of ghrelin secretion in children is different from that in adults. Moreover, how ghrelin secretion is regulated in childhood as a function of fat mass is still unclear.

Circulating ghrelin levels in the newborn are positively associated with gestational age

objective  Ghrelin exerts potent GH‐releasing activity and stimulates food intake. Circulating ghrelin levels are increased in anorexia and cachexia, reduced in obesity and restored by weight recovery. Newborns are characterized by GH hypersecretion associated with low IGF‐I levels reflecting peripheral GH resistance.

Circulating ghrelin levels in newborns are not associated to gender, body weight and hormonal parameters but depend on the type of delivery

Ghrelin, a new gastric-derived hormone, probably plays a major role in managing energy balance and the neuroendocrine response to starvation. Information about the age-related variation in ghrelin secretion is scanty. We measured circulating ghrelin levels in 93 full term newborns adequate for gestational age, in 39 normal children and in 19 lean healthy adults. Our findings demonstrate that ghrelin levels are independent of age and gender from birth to adulthood. Interestingly, ghrelin secretion at birth is not associated to body weight and hormonal parameters such as GH, insulin and leptin levels. On the other hand, ghrelin levels seem dependent on the type of delivery, being lower in newborns after caesarean section with respect to those after normal delivery.

Molecular characterization of HHV-8 positive primary effusion lymphoma reveals pathogenetic and histogenetic features of the disease

BACKGROUND Primary effusion lymphoma (PEL) associates with HHV-8 infection, preferentially develops in immunodeficient patients and grows in the serous body cavities. PEL derives from post-germinal center, pre-terminally differentiated B-cells. The pathogenesis of PEL is unclear and the sole identified genetic lesions are human herpesvirus type-8 (HHV-8) infection in all cases and EBV infection in 70% of cases. Epstein-Barr virus (EBV) infection in PEL displays a latency I phenotype. OBJECTIVES To clarify the pathogenesis and histogenesis of PEL by investigating (1) the lymphoma karyotype; (2) the expression status of the Met tyrosine kinase receptor and of its ligand hepatocyte growth factor (HGF); (3) the molecular profile of EBV, with particular focus on mutations of EBNA-1 genes, which are thought to affect viral tumorigenicity in EBV-infected neoplasms displaying the latency I phenotype. STUDY DESIGN Twenty-four PEL (nine cell lines and 15 primary specimens) formed the basis of the study. Karyotypes were investigated by conventional cytogenetics and fluorescent in situ hybridization (FISH) in selected cases. The expression status of Met and HGF was defined by multiple techniques, including RT-PCR, FACS analysis, immunocytochemistry, Western blot studies and ELISA. The molecular profile of EBNA-1 genes of EBV were investigated by DNA direct sequencing. RESULTS Trisomy 7, trisomy 12 and breaks at 1q21-q25 are recurrently associated with PEL. PEL consistently co-express Met and HGF both at the mRNA and protein level. Among aggressive B-cell lymphomas, Met/HGF co-expression appears to be relatively specific for PEL. The EBNA-1 gene of EBV displays a high degree of genetic heterogeneity in PEL, with no preferential association with one specific variant. CONCLUSIONS PEL associates with recurrent chromosomal alterations, suggesting that viral infection is not sufficient for tumor development and that lesions of cellular genes may be required. The expression of Met/HGF by PEL cells may bear implications for the lymphoma proliferation and growth pattern, since Met/HGF interactions influence cell mitogenesis and motogenesis. EBV infection in PEL displays a latency I phenotype and fails to associate with specific EBNA-1 variants, suggesting that the role of EBV in PEL is not mediated by the major transforming pathways currently known in EBV positive lymphomas.

Standard light breakfast inhibits circulating ghrelin level to the same extent of oral glucose load in humans, despite different impact on glucose and insulin levels.

Ghrelin levels are increased by fasting and energy restriction, decreased by food intake, glucose load and insulin but not by lipids and amino acids. Accordingly, ghrelin levels are elevated in anorexia and cachexia and reduced in obesity. Herein we compared the effects of a standardized light breakfast (SLB) on morning circulating ghrelin levels with those of oral glucose load (OGTT) in normal subjects. Specifically, 8 young adult volunteers [age (mean±SEM): 28.0±2.0 yr; body mass index (BMI): 22.4±0.6 kg/m2] underwent the following testing sessions: a) OGTT (100 g po at 0 min, about 400 kcal); b) SLB (about 400 kcal, 45% carbohydrates, 13% proteins and 42% lipids at 0 min) on three different days; c) placebo (100 ml water po). In all sessions, at baseline, blood samples were withdrawn twice at 5-min interval to characterize the inter- and intra-individual reproducibility of the variables assayed. After placebo and OGTT, blood samples were withdrawn every 15 min up to +120 min. After SLB, blood samples were taken at 60 min only. Ghrelin, insulin and glucose levels were assayed at each time point in all sessions. Similarly to insulin and glucose levels, at baseline, ghrelin showed remarkable intra-subject reproducibility both in the same sessions and among the different sessions. Placebo did not significantly modify ghrelin, insulin and glucose. OGTT increased (p<0.01) glucose (baseline vs peak: 80.0±3.6 vs 140.5±6.3 mg/dl) and insulin (20.2±6.2 vs 115.3±10.3 mU/l) levels. SLB increased (p<0.05) both insulin (16.3±1.8 vs 48.3±6.3 mU/l) and glucose (74.5±3.7 vs 82.9±3.1 mg/dl) levels. Notably both the insulin and glucose increases after OGTT were significantly higher (p<0.01) than that induced by SLB. After OGTT, ghrelin levels underwent a significant reduction (baseline vs nadir: 355.7±150.8 vs 243.3±98.8 pg/ml; p<0.05) reaching the nadir at time +60 min. Similarly, ghrelin levels 60 min after SLB (264.8±44.8 pg/ml) were significantly (p<0.01) lower than at baseline (341.4±54.9 pg/ml). No significant differences in the reduction of ghrelin levels after OGTT and SLB were observed. In conclusion, these findings show that light breakfast inhibits ghrelin secretion to the same extent of OGTT in adults despite lower variations in glucose and insulin levels.

The role of cytokines in the pathogenesis and management of AIDS-related lymphomas.

AIDS-related non-Hodgkin lymphomas (AIDS-NHL) consistently derive from B-cells and are characterized by extreme clinical aggressiveness. At histological level, AIDS-NHL are classified as AIDS-related Burkitts lymphoma (AIDS-BL), AIDS-related diffuse large cell lymphoma (AIDS-DLCL) and AIDS-related primary effusion lymphoma (AIDS-PEL). The role of cytokines in the pathogenesis and management of AIDS-NHL has been studied to a certain extent. Production of large quantities of human IL-10 occurs frequently in AIDS-BL and correlates with latent EBV infection of the tumor clone. Lesser amounts of the cytokine are released in EBV negative cases. The pathogenetic role of IL-10 in AIDS-BL is suggested by the observation that IL-10 antisense oligonucleotides inhibit proliferation of the lymphoma A significan fraction of AIDS-BL cell lines produce TNFβ Among AIDS-NHL, the release of TNFβ appears to be specific for AIDS-BL. The pathogenetic relevance of TNFβ in lymphomagenesis is suggested by the observation that some BL cell lines use TNFβ as an autocrine growth factor. Some cases of AIDS-BL, particularly those carrying EBV infection, also secrete IL-6, IL-7 and IL-12. With respect to AIDS-DLCL, many cases express the IL-6R, rendering these cells responsive to the paracrine stimulation by the IL-6 produced by nearby T-cells, macrophages and endothelial cells which are frequently abundant in these tumor samples. The tumor clone itself, however, generally fails to release IL-6. AIDS-PEL is characterized by secretion of large amounts of IL-6 and IL-10. Some PEL cases also release oncostatin M. Apart from human IL-6, PEL also express viral IL-6, which is encoded by the HHV-8 genome. The biological relevance of both IL-6 and IL-10 in PEL proliferation and growth has been recently clarified in vitro and in vivo. Overall, these data suggest that activation of different cytokine loops clusters with different clinico-pathologic categories of AIDS-NHL and may represent the potential target of novel therapeutic strategies.

Clarithromycin Resistance of Helicobacter pylori Strains Isolated from Children’ Gastric Antrum and Fundus as Assessed by Fluorescent In‐situ Hybridization and Culture on Four‐Sector Agar Plates

Aim:  To assess validity of culture on four‐sector agar plates and fluorescent in‐situ hybridization (FISH) test, and clarithromycin resistance rate in Helicobacter pylori strains isolated from children in the last 10 years.