Growth modes of nanoparticle superlattice thin films.

We report on the fabrication and characterization of iron oxide nanoparticle thin film superlattices. The formation into different film morphologies is controlled by tuning the particle plus solvent-to-substrate interaction. It turns out that the wetting vs dewetting properties of the solvent before the self-assembly process during solvent evaporation plays a major role in determining the resulting film morphology. In addition to layerwise growth three-dimensional mesocrystalline growth is also evidenced. The understanding of the mechanisms ruling nanoparticle self-assembly represents an important step towards the fabrication of novel materials with tailored optical, magnetic or electrical transport properties.

Self-assembled iron oxide nanoparticle multilayer: x-ray and polarized neutron reflectivity.

We have investigated the structure and magnetism of self-assembled, 20 nm diameter iron oxide nanoparticles covered by an oleic acid shell for scrutinizing their structural and magnetic correlations. The nanoparticles were spin-coated on an Si substrate as a single monolayer and as a stack of 5 ML forming a multilayer. X-ray scattering (reflectivity and grazing incidence small-angle scattering) confirms high in-plane hexagonal correlation and a good layering property of the nanoparticles. Using polarized neutron reflectivity we have also determined the long range magnetic correlations parallel and perpendicular to the layers in addition to the structural ones. In a field of 5 kOe we determine a magnetization value of about 80% of the saturation value. At remanence the global magnetization is close to zero. However, polarized neutron reflectivity reveals the existence of regions in which magnetic moments of nanoparticles are well aligned, while losing order over longer distances. These findings confirm that in the nanoparticle assembly the magnetic dipole-dipole interaction is rather strong, dominating the collective magnetic properties at room temperature.

Domain wall dynamics in amorphous and nanocrystalline FeCoMoB microwires.

We have studied the domain wall dynamics in amorphous and nanocrystalline FeCoMoB microwires. The domain wall propagation velocity has been found very fast (up to 5000 m/s) for the as-cast sample. Annealing at 575 K/1 h leads to the stress relief and sample homogenization and the domain wall velocity even increases to 5300 m/s. However, the domain wall dynamics is highly sensible to the temperature of a measurement. Annealing at 775 K/1 h leads to the appearance of the nanocrystalline structure with much higher temperature stability. The maximum domain wall velocity decreases (2800 m/s), however the domain wall dynamics is much stable with the temperature.

Template-assisted self-assembly of individual and clusters of magnetic nanoparticles.

The deliberate control over the spatial arrangement of nanostructures is the desired goal for many applications such as, for example, in data storage, plasmonics or sensor arrays. Here we present a novel method to assist the self-assembly process of magnetic nanoparticles. The method makes use of nanostructured aluminum templates obtained after anodization of aluminum discs and the subsequent growth and removal of the newly formed alumina layer, resulting in a regular honeycomb-type array of hexagonally shaped valleys. The iron oxide nanoparticles, 20 nm in diameter, are spin-coated onto the surface of honeycomb nanostructured Al templates. Depending on the size, each hexagon site can host up to 30 nanoparticles. These nanoparticles form clusters of different arrangements within the valleys, such as collars, chains and hexagonally closed islands. Ultimately, it is possible to isolate individual nanoparticles. The strengths of the magnetic interaction between particles in a cluster are probed using the memory effect known from the coupled state in superspin glass systems.

Dehydroepiandrosterone sulfate (DHEAS) secretion in early and advanced solid neoplasms: selective deficiency in metastatic disease.

Several endogenous hormones have been proven to stimulate cancer growth, whereas at present very few hormones are known to display oncostatic activity. The most widely investigated antitumor hormone is the pineal indole melatonin (MLT), and cancer progression has been shown to be associated with a decline in MLT secretion. Recently, another hormone, the adrenal steroid dehydroepiandrosterone-sulfate (DHEAS), has appeared to exert antitumor effects similar to those previously described for MLT. In addition, experimental studies suggest a diminished DHEAS production with neoplastic progression. This preliminary study was performed to evaluate the daily secretion of DHEAS in a group of early and advanced cancer patients. The study included 70 patients with solid tumors (gastrointestinal tract tumors: 28; breast cancer: 24; non-small cell lung cancer: 18), 28 without and 42 with distant metastases. The serum levels of DHEAS were measured by RIA in blood samples collected in the morning. The control group consisted of 100 age- and sex-matched healthy subjects. No significant difference in mean serum levels of DHEAS was observed between controls and non-metastatic patients. In contrast, metastatic patients, irrespectively of tumor histotype, showed significantly lower mean levels of DHEAS with respect to either controls or non-metastatic patients. Moreover, metastatic patients with visceral locations showed significantly lower values of DHEAS than those with bone or soft-tissue metastases. This preliminary study would suggest there to be a deficiency in the daily DHEA secretion in patients with disseminated cancer. Further studies evaluating circadian DHEAS secretion in relation in that of the pineal hormone MLT will be required to better define the biological significance of the advanced cancer-related decline in endogenous DHEAS production.

Vascular endothelial growth factor (VEGF) serum levels during cancer immunotherapy with IL-2: preliminary considerations.

Neoangiogenesis has been proven to play a fundamental role in promoting cancer spread, and vascular endothelial growth factor (VEGF) is known to represent one of the most important angiogenic factors. The present study was planned to investigate changes in VEGF secretion in cancer patients undergoing immunotherapy with IL-2, with the aim of establishing whether VEGF variations play a role in mediating the IL-2-induced control of neoplastic diseases. The study involved 14 metastatic renal cell cancer patients treated with IL-2 immunotherapy (6 million IU/day subcutaneously for 6 days/week for 4 weeks). The clinical response consisted of partial response (PR) in 3, stable disease (SD) in 6 and progressive disease (PD) in the remaining 5 patients. VEGF serum levels were measured by an enzyme immunoassay designed to determine both bound and unbound VEGF. No significant changes in VEGF mean levels occurred during IL-2 therapy. Moreover, neither in patients with PR or SD nor in those with PD did the mean serum levels of VEGF change significantly in response to IL-2. This preliminary study seems to exclude that changes in the angiogenic factor VEGF may play a role in mediating the therapeutic efficacy of IL-2 cancer immunotherapy. However, since the method of measurement used in our study was designed to detect the total amount of VEGF, it cannot be excluded that changes in the free fraction of the molecule may occur during IL-2 cancer immunotherapy.

Physiopathology of IL-12 in human solid neoplasms: blood levels of IL-12 in early or advanced cancer patients, and their variations with surgery and immunotherapy.

Experimental studies have shown that IL-12 plays an important role in the activation of the anticancer immune defenses. Unfortunately, at present the behavior of IL-12 secretion in human neoplasms remain to be established. In an attempt to draw some preliminary data about IL-12 secretion in human cancer, in the present study we have evaluated serum levels of IL-12 in a group of non-metastatic and metastatic solid tumor patients in relation to the survival time, and their changes in surgically treated cancer patients and in metastatic patients undergoing immunotherapy with IL-2. Mean serum levels of IL-12 were significantly higher metastatic patients (n = 40) than in those with locally limited solid neoplasm (n = 16). Moreover, within the metastatic group, the percent of 1-year survival was significantly higher in patients with abnormally elevated blood concentrations of IL-12 than in those with normal values. In the group of 10 patients surgically treated for gastrointestinal tract tumors, the surgical operation induced a significant decline in IL-12 mean serum levels. Finally, in a group of 23 metastatic renal cell cancer patients treated with IL-12 immunotherapy (6 million IU/day S.C. for 6 days/week for 4 weeks), the treatment was associated with a significant and progressive increase in IL-12 mean values. Moreover, serum mean levels of IL-12 observed in therapy in patients with response or stable disease were significantly higher than those found in progressing patients. This preliminary study seems to suggest that the evidence of high levels of IL-12 may have a favourable prognostic significance in solid tumor patients, either in baseline conditions or in response to IL-2 cancer immunotherapy.

Endocrinological study of the dopaminergic regulation of prolactin release in metastatic breast cancer.

AIMS AND BACKGROUND: Prolactin (PRL) may be a growth factor for breast cancer. Abnormally high levels of PRL have been proven to be associated with a poor prognosis in metastatic breast cancer. However, most studies have been limited to the evaluation of basal levels of PRL rather than its response to the classical endocrine dynamic tests. This study was performed to analyse the dynamic secretion of PRL under stimulatory and inhibitory tests in metastatic breast cancer. METHODS: The study included 10 untreated metastatic breast cancer women, who were evaluated after the classical stimulatory and inhibitory tests for PRL secretion with the antidopaminergic agent Metoclopramide (10 mg iv as a bolus) and with L-dopa, respectively. Serum levels of PRL were measured by RIA before and at subsequent intervals after drug administration. PRL levels were considered to be elevated when they were higher than 25 ng/ml. RESULTS: Abnormally high basal levels of PRL were seen in 6/10 patients. L-dopa was unable to inhibit PRL secretion, whose mean concentrations paradoxically significantly increased in response to L-dopa, with values comparable to those observed after the classical stimulatory test with metoclopramide. CONCLUSIONS: This study confirm the existence of hyperprolactinemia associated with metastatic breast cancer. In addition, by showing a paradoxical rise of PRL in response to L-dopa, which inhibits PRL secretion in physiological conditions, this study would suggest that breast cancer-related hyperprolactinemia may depend at least in part on endogenous disease-related neuroendocrine alterations.

Structural and magnetic characterization of self-assembled iron oxide nanoparticle arrays.

We report about a combined structural and magnetometric characterization of self-assembled magnetic nanoparticle arrays. Monodisperse iron oxide nanoparticles with a diameter of 20 nm were synthesized by thermal decomposition. The nanoparticle suspension was spin-coated on Si substrates to achieve self-organized arrays of particles and subsequently annealed at various conditions. The samples were characterized by x-ray diffraction, and bright and dark field high resolution transmission electron microscopy. The structural analysis is compared to magnetization measurements obtained by superconducting quantum interference device magnetometry. We can identify either multi-phase Fe(x)O/γ-Fe(2)O(3) or multi-phase Fe(x)O/Fe(3)O(4) nanoparticles. The Fe(x)O/γ-Fe(2)O(3) system shows a pronounced exchange bias effect which explains the peculiar magnetization data found for this system.

M-H loop tracer based on digital signal processing for low frequency characterization of extremely thin magnetic wires.

A high-sensitivity ac hysteresis loop tracer has been developed to measure the low frequency hysteresis loop of soft magnetic materials. It has been applied successfully to characterize straight pieces of amorphous glass-covered microwires with metallic nucleus down to 1.5 microm thick. Based on the electromagnetic induction law, the proposed design is extremely simple and exploits the capabilities of commercially available data acquisition cards together with digital signal processing in order to achieve high-sensitivity without the need of expensive analog equipment.

Electrolyte monitoring in patients undergoing peripheral blood stem cell collection.

In recent years peripheral blood stem cell (PBSC) collection for allogeneic or autologous transplantation has experienced an increased use in the onco-hematological setting. The latest generation cell separators allow a satisfactory and safe PBSC collection. Nevertheless, as in all therapeutic apheresis procedures, patients may experience procedure-related side-effects, mainly vasovagal reactions or symptoms related to hypocalcemia and/or hypomagnesemia. We investigated electrolyte changes in 18 patients, with a median age of 46 years (range 7-62), undergoing PBSC collection from January to April 1998. A significant decrease in total calcium in the final sample (9.65 +/- 0.7 mg/dL) with respect to the basal one (9.2 +/- 0.6 mg/dL, P < 0.05) was observed; also ionized calcium decreased markedly from the first sample drawn at +30 minutes: 1.22 +/- 0.14 vs. 1.03 +/- 0.15 mmol/L (P < 0.05), and a highly significant difference emerged when basal value were compared to the final value: 1.22 +/- 0.14 vs. 0.94 +/- 0.13 mmol/L (P < 0.0001). Similar findings affected potassium concentration: 4.1 +/- 0.4 vs. 3.3 +/- 0.3 mEq/L (P < 0.0001). Three out of eighteen patients (16.7%) reached a final potassium level <3.0 mEq/L, and eight out of eighteen (44.5%) showed a potassium concentration decrease >20% with respect to the basal value. A mild metabolic alkalosis occurred during the procedure: pH increased from 7.35 +/- 0.02 to 7.43 +/- 0.028 (P < 0.001), and plasma bicarbonate concentration increased from 27.48 +/- 2.21 to 32.44 +/- 2.52 mmol/L (P < 0.01). Sodium and chloride did not differ in the final sample with respect to the basal sample. None of our patients experienced clinically relevant side effects related to severe electrolyte changes (i.e., >20% with respect to the basal value). Because our current therapeutic schedules include patients older than 50 years in the PBSC collection and transplantation program and since it is well known that subclinical myocardial disease may occur in up to 4% of middle-aged males, we suggest that patients aged 50 or older undergoing PBSC collection procedures be carefully monitored in order to identify significant electrolyte variation, especially if they present with low serum potassium levels. However, further investigation of larger patient series are needed to determine the clinical relevance of serum potassium changes during apheresis.

Effects of somatostatin on acute pancreatitis induced in rats by injection of taurocholate and trypsin into a temporarily closed duodenal loop.

The effect of somatostatin on the course and severity of experimental pancreatitis was tested. Acute pancreatitis was induced in 210 Sprague-Dawley rats by injecting a 4.3% sodium taurocholate solution, saturated with trypsin, into a temporarily closed duodenal loop. Immediately after the end of the surgical procedure somatostatin or, alternatively, normal saline were administered as a bolus followed by continuous subcutaneous infusion for 9 h. Ninety rats (30 untreated, 30 saline-treated and 30 somatostatin-treated) were sacrificed 10 h after the induction of pancreatitis to assess the histologic severity of pancreatic lesions, the amount of peritoneal exudate and the circulating levels of amylase. In another 120 rats (40 untreated, 40 saline-treated and 40 drug-treated) the mortality rate was evaluated so that the histologic examination of the pancreas followed spontaneous death. In sacrificed animals somatostatin treatment lowered serum amylase levels and definitely improved pancreatic histopathology (edema, leucocyte infiltration and necrosis). The drug prevented the occurrence of severe necrosis in all treated animals. Somatostatin did not affect the mortality rate of pancreatitic rats (70%) although post-mortem histologic examination revealed significantly less pancreatic histopathology in drug-treated rats than in their controls.