Bi-Component Nanostructured Arrays of Co Dots Embedded in Ni80Fe20 Antidot Matrix: Synthesis by Self-Assembling of Polystyrene Nanospheres and Magnetic Properties.

A bi-component nanostructured system composed by a Co dot array embedded in a Ni80Fe20 antidot matrix has been prepared by means of the self-assembling polystyrene nanospheres lithography technique. Reference samples constituted by the sole Co dots or Ni80Fe20 antidots have also been prepared, in order to compare their properties with those of the bi-component material. The coupling between the two ferromagnetic elements has been studied by means of magnetic and magneto-transport measurements. The Ni80Fe20 matrix turned out to affect the vortex nucleation field of the Co dots, which in turn modifies the magneto-resistance behaviour of the system and its spinwave properties.

Evaluation of cholesterol metabolism in cerebrotendinous xanthomatosis.

BACKGROUND: Cerebrotendinous xanthomatosis (CTX) is a treatable bile acid disorder caused by mutations of CYP27A1. The pathogenesis of neurological damage has not been completely explained. Oral chenodeoxycholic acid (CDCA) can lead to clinical stabilization, but in a subgroup of patients the disease progresses despite treatment. In the present study, we aimed at clarifying cholesterol metabolism abnormalities and their response to CDCA treatment, in order to identify reliable diagnostic and prognostic markers and understand if differences exist between stable patients and those with neurological progression. METHODS: We enrolled 19 untreated CTX patients and assessed serum profile of bile acids intermediates, oxysterols, cholesterol, lathosterol, and plant sterols. Then we performed a long-term follow up during CDCA therapy, and compared biochemical data with neurological outcome. RESULTS: We observed increase of cholestanol, 7α-hydroxy-4-cholesten-3-one (7αC4), lathosterol, and plant sterols, whereas 27-hydroxycholesterol (27-OHC) was extremely low or absent. CDCA treatment at a daily dose of 750 mg normalized all biochemical parameters except for 7αC4 which persisted slightly higher than normal in most patients, and 27-OHC which was not modified by therapy. Biochemical evaluation did not reveal significant differences between stable and worsening patients. DISCUSSION: Cholestanol and 7αC4 represent important markers for CTX diagnosis and monitoring of therapy. Treatment with CDCA should aim at normalizing serum 7αC4 as well as cholestanol, since 7αC4 better mirrors 7α-hydroxylation rate and is thought to be correlated with cholestanol accumulation in the brain. Assessment of serum 27-OHC is a very good tool for biochemical diagnosis at any stage of disease. Lathosterol and plant sterols should be considered as additional markers for diagnosis and monitoring of therapy. Further studies including long-term assessment of bile acid intermediates in cerebrospinal fluid are needed in patients who show clinical progression despite treatment.

Duodenal diverted sleeve gastrectomy with ileal interposition does not cause biliary salt malabsorption.

BACKGROUND: Duodenal diverted sleeve gastrectomy with ileal interposition (DDSG-II) is a bariatric-metabolic operation designed to treat type 2 diabetes mellitus (T2DM). It is restrictive (SG) but also acts on the small bowel with functional effects. The objective of the present study was to investigate whether or not it is also a malabsorptive operation. METHODS: Twelve obese patients (9 female and 3 male) affected by T2DM had DDSG-II. Follow-up was every 3 months, and the results after 1 year are reported here. Clinical conditions, related to diabetes and malnutrition, changes in weight, body mass index, fasting glucose plasma levels, HbA1c (glycated hemoglobin %), basal insulin, vitamin B12, folic acid, vitamin D, total proteins, albumin, and hemoglobin were recorded. Basal plasma levels of FGF19 (pg/mL) and of 7α-hydroxy-4-cholesten-3-one (C4) (µg/dL) were also determined for the diagnosis of biliary salt malabsorption. The results were expressed as mean±SEM, and the differences between times compared by the Mann Whitney U test; P<.05 was considered significant. RESULTS: After 1 year, all patients had a significant weight loss (-33.2±3 kg) with T2DM remission according to the American Diabetes Association criteria (11), criteria. No significant changes in total proteins, albumin, hemoglobin, and vitamins (B6, B12, and D) were detected. C4 did not change after the operation (2±.5 µg/dL versus 1.6±.5 µg/dL), whereas FGF19 significantly increased (from 85±11.2 pg/mL to 166.4±28.2 pg/mL, P<.04). Only 2 patients had mild symptoms of malabsorption. CONCLUSIONS: DDSG-II is effective for treatment of T2DM obese patients, increases the enterokine FGF19, and does not cause biliary salt malabsorption.

Age-associated alterations in cholesterol homeostasis: evidence from a cross-sectional study in a Northern Italy population.

BACKGROUND: The modifications of cholesterol metabolism associated with aging are ill-defined. The objective of this study was to define age-associated alterations of the different metabolic pathways controlling cholesterol homeostasis by analyzing circulating sterols. METHODS: We analyzed serum samples collected from 201 adult (75 male, 126 female) subjects within the epidemiological MICOL study (Multicentrica Italiana Colelitiasi). The age range was 38-79 years; 103 had evidence of gallstones. The concentrations of the different sterols, recognized as markers of the main pathways of cholesterol homeostasis, were analyzed by gas chromatography-mass spectrometry, including lathosterol (synthesis), campesterol and sitosterol (absorption), and 7α-hydroxy-4-cholesten-3-one (degradation to bile acids). RESULTS: A significant direct correlation was detected between age and cholesterol levels (r =0.34, P<0.01). The lathosterol/cholesterol ratio was lower in older age quartiles (P<0.05 by analysis of variance), with an inverse correlation between the lathosterol/cholesterol ratio and age (r=-0.32, P<0.01). Such correlation was particularly evident in females. The campesterol/cholesterol and sitosterol/cholesterol ratios were inversely correlated with aging in control, but not in gallstone patients. The levels of 7α-hydroxy-4-cholesten-3-one were not correlated with age. CONCLUSION: These data show a reduction of cholesterol synthesis with aging which is associated with increased circulating cholesterol levels. The finding might be related to a reduced metabolic need for cholesterol in advancing age, leading to a downregulation of the main mechanisms of cholesterol intake in the liver. A different age-related behavior was observed in gallstone-free versus gallstone patients regarding cholesterol absorption. The possible implications in terms of the pharmacological management of hypercholesterolemia in the elderly remain to be defined.

Phase transitions in a disordered system in and out of equilibrium.

The equilibrium and nonequilibrium disorder-induced phase transitions are compared in the random-field Ising model. We identify in the demagnetized state the correct nonequilibrium hysteretic counterpart of the T=0 ground state, and present evidence of universality. Numerical simulations in d=3 indicate that exponents and scaling functions coincide, while the location of the critical point differs, as corroborated by exact results for the Bethe lattice. These results are of relevance for optimization, and for the generic question of universality in the presence of disorder.