Biomedical subjects

S Di Bella

Publications and source records attributed to S Di Bella.

16 recordsLinked to original sources

PubMed2005

Is leptin the link between fat and bone mass?

Leptin is a cytokine-like hormone which is considered the link between fat and bone; it is produced by adipocytes and osteoblasts, regulates food intake via specific receptors located in the central nervous system (CNS) and bone mass through alternate pathways: one involving a direct stimulatory effect on bone formation; and another indirect effect through the CNS that suppresses bone formation. Leptin exerts a direct stimulatory effect on osteoblast differentiation and on bone growth if directly administered, while it exerts an inhibitory effect on bone formation if administered in the CNS. It is therefore unclear whether leptin should be considered an antiosteogenic factor or an anabolic agent for bone formation: in all probability, leptin has a broader role in human physiology and in particular its action has evolved in order to synchronize periods of bone growth, mineral accretion and fertility with periods of food availability, while it restricts growth and reproduction during periods of nutritional stress.

Adipocytes↗

PubMed2004

Helicobacter pylori impairs iron absorption in infected individuals.

BACKGROUND: Infection with Helicobacter pylori is recognised as a major risk factor for chronic gastritis, peptic ulcer disease and gastric cancer. The association between H. pylori infection and iron deficiency anaemia has been established. Multiple mechanisms have been advocated to explain the relationship between H. pylori and iron status and their association might reduce iron deposit. AIM: Aim of this study was to investigate whether H. pylori infection affects iron absorption. METHODS: The study was designed on a prospective basis. Fifty-five subjects underwent upper gastrointestinal endoscopy and biopsy to investigate the presence of H. pylori and, when this was positive, also search of serum anti-CagA was performed. Tests included an oral iron absorption test with the administration of 1 mg/kg of Fe2+. Iron levels were measured before and 2 h after iron administration (delta iron). H. pylori-positive subjects were administered antibiotic therapy for 1 week and, 2 months later, the oral iron absorption test was repeated and urea-breath test was first performed. RESULTS: H. pylori-positive subjects had lower serum level of ferritin and lower delta iron compared to H. pylori-negative subjects. That difference is significant in anaemic women and is independent of the presence of serum anti-CagA antibodies. After H. pylori eradication iron absorption test was similar to those of non-infected subjects. CONCLUSION: H. pylori infection impairs iron uptake. That mechanism, together with others, may contribute to the depletion of iron in infected patients.

Adult↗

PubMed2001

Dipolar donor-acceptor-substituted schiff base complexes with large off-diagonal second-order nonlinear optical tensor components.

The synthesis, characterization, and two-dimensional second-order nonlinear optical (NLO) response of a dipolar NiII donor- acceptor Schiff base complex and the related ligand are reported. Electric-field-induced second-harmonic generation and harmonic light (hyper-Rayleigh) scattering techniques, in combination with INDO/SCI-SOS theoretical calculations, were used to investigate the vector part of the hyperpolarizability tensor and the two-dimensional character of the molecular nonlinearity, respectively. Off-diagonal hyperpolarizability tensors can be related to charge-transfer transitions that are polarized perpendicular to the molecular dipolar axis, while parallel transitions account for the diagonal hyperpolarizability tensor. The role of the metal center in enhancing the two-dimensional NLO response of such molecules is twofold since it acts both as the donor and the bridging moiety of the planar donor-(pi-conjugate-bridge)-acceptor system. These dipolar two-dimensional molecules are interesting candidates from the perspective of polarization-independent NLO materials.

Journal Article↗

PubMed1968