Fitness model for the Italian interbank money market.

We use the theory of complex networks in order to quantitatively characterize the formation of communities in a particular financial market. The system is composed by different banks exchanging on a daily basis loans and debts of liquidity. Through topological analysis and by means of a model of network growth we can determine the formation of different group of banks characterized by different business strategy. The model based on Pareto's law makes no use of growth or preferential attachment and it reproduces correctly all the various statistical properties of the system. We believe that this network modeling of the market could be an efficient way to evaluate the impact of different policies in the market of liquidity.

[Beta-cell secretion in patients with thalassemia major]. / Secrezione beta-cellulare nei pazienti con thalassemia major.

Diabetes mellitus is one of the main endocrinological disease complicating the course of thalassemia major. This study aimed evaluate beta-cell secretion in 24 patients with thalassemia major attending the hematological Day Hospital at the Pediatric Clinic in Modena where transfusion therapy is performed in all thalassemic patients so as to maintain minimum hemoglobin levels above 10.5 g/dl, together with intensive ferrochelating therapy (desferrioxamine 50-60 mg/kg/die s.c. 6 days a week). A C peptide challenge with glucagon was performed in three patients already receiving insulin therapy for diabetes mellitus; this unexpectedly revealed a slight residual beta-cell secretion. An intravenous glucose tolerance test (IVGTT) was performed in the remaining 21 non-diabetic patients, with widely varying findings regarding insulin secretion: from below 50 microUl/ml in 5 patients to above 200 microUl/ml in 5 patients, and between 50 and 150 microUl/ml in the remaining 11 patients. This study therefore confirmed that insulin secretion frequently alters in thalassemic patients. Moreover, insulin secretion is not correlated to ferritinemia or influenced by familiar diabetes or patient age.

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)

[Use of high-dose intravenous immunoglobulins in pediatric hematology]. / L'uso di immunoglobuline endovena ad alte dosi in ematologia pediatrica.

High-dose intravenous immunoglobulin play a critical role in a lot of pediatric hematologic diseases. In our experience we studied the effects of IVIG treatment in 63 children. They all tolerated IVIG preparations in every infusions; no trouble caused the interruption of treatment. The efficacy is evident in immunomediated diseases, most of all ITP, and controlling septic episodes in immunocompromised patients (ALL, AIDS, marrow bone transplantation). An important problem is the cost of preparation; but we may consider that this treatment, for example in ITP, reduces hospitalization for children, necessity of platelets' transfusions, use of steroids and, therefore, their collateral effects. Hence, we assert that the social cost of the management of ITP disease is not higher in children treated with IVIG. Furthermore, short hospitalization for IVIG therapy contributes to accept this disease. It should be advisable to make controlled studies to define with more accuracy the role of this preparation and the modality of its use in the different clinical conditions in which it is employed.

Acute beta-interferon or thymopentin administration increases plasma growth hormone and cortisol levels in children.

The interaction between the immune and endocrine systems has recently been investigated. Hodgkin's disease represents a model of immune disturbance frequently associated with endocrine impairment. The present study evaluated the effect of the acute administration of beta-interferon or thymopentin on plasma growth hormone, prolactin and cortisol levels in children with Hodgkin's disease (N = 8) and age- and sex-matched healthy controls (N = 8). beta-interferon (1,000,000 IU), thymopentin (50 mg) or placebo (saline) were injected after two basal blood samples (-15 and 0) and further samples were drawn at 15, 30, 45, 60, 90 and 120 min. Plasma growth hormone, prolactin and cortisol levels were measured by specific RIAs. Plasma prolactin levels did not show significant change following beta-interferon or thymopentin injection in either the controls or the patients. In the patients with Hodgkin's disease, beta-interferon injection induced a significant increase in both plasma growth hormone and cortisol levels, while thymopentin was not effective. In controls both thymopentin and beta-interferon administration increased plasma growth hormone and cortisol levels. These results indicate that beta-interferon and thymopentin are immune substances active on the release of growth hormone and cortisol in healthy children. The lack of effect of thymopentin in children with Hodgkin's disease suggests an impairment of the immune-endocrine interaction in these patients.

Hematoporphyrin uptake by experimentally induced cholesteatomas in an animal model.

Photodynamic therapy is based on the production of a cytotoxic factor by porphyrins, particularly hematoporphyrin (HP), when exposed to light of a suitable wavelength and intensity. The uptake of HP is notably large in tissues with a high mitotic index. Although cholesteatomas are not malignant tumors, our working hypothesis was that their high lipid content might result in their exhibiting a remarkable affinity to HP, which is normally carried in the blood by lipoproteins. Cholesteatomas were induced in rabbits using the Tübingen procedure (closure of the auditory canal by sutures). Animals were killed 30-40 days later at intervals of 1, 3, 6, 12, and 24 h following intravenous HP administration (5 mg/kg). Specimens were divided into two portions, one for histological examination and the other for biochemical study. The latter revealed that HP accumulates in experimental cholesteatomas, with a maximum uptake after 3 h. The level then gradually decreases, although at a lower rate than in the liver, but remains considerably high even after 24 h. These results suggest that the photodynamic treatment of cholesteatomas should be feasible in our animal model, although such treatment is still speculative in man.