Electronic properties modifications of single-wall boron nitride with lithium atom intercalation.

In this work we use the ab initio calculations to study the intercalation of lithium (Li) atoms in the channels of the single-wall boron nitride nanotube (BNNT) bundles. The relaxed structure as well as the electronic band structure were obtained. Results reveals that Li insertion modifies the band structure by shifting the Fermi energy to conduction band. The Li atoms act as electron donors and this modifies the electronic properties of the BNNT bundles due the intercalation. The electronic properties changes induced in the effects are dependent on Li atom numbers per nanotube.

Vibrational properties of RbNd(WO4)2: high pressure Raman study, structural and phonon calculations.

RbNd(WO(4))(2) was investigated by high pressure Raman spectroscopy in the 0.1-12.3 GPa pressure interval. The assignment of modes was made based on lattice dynamics calculations and the results of these calculations helped us to also discuss the high pressure behavior of phonon spectra in this material. Our results show that a double oxygen bridge plays a fundamental role in the vibrational properties of this system. A density functional theory (DFT) calculation of hydrostatic pressure effects on RbNd(WO(4))(2) was performed in order to understand the effect of internal bond changes on the vibrational properties of RbNd(WO(4))(2). No pressure induced structural phase transition was observed in the Raman study at room temperature, and the DFT calculation (T = 0 K) is consistent with this result. The anomalous softening of the bridge stretching mode at 770 cm(-1) was attributed to the decrease of W-O1-W bond angle with increasing pressure.

[Renal involvement in systemic sclerosis]. / Sclerosi sistemica e coinvolgimento renale.

Systemic sclerosis is an autoimmune disease characterized by fibrosis of the skin and internal organs. Raynaud's phenomenon generally precedes other disease manifestations. The distribution of skin lesions and the internal organ involvement are the basis for the classification into limited and diffuse forms of the disease. Clinically evident renal disease is observed in 10-40% of patients. The most common renal presentation is renal crisis, characterized by acute onset of renal failure and severe hypertension; some patients remain normotensive, showing microangiopathic hemolytic anemia. Renal complications due to penicillamine may occur in some patients. Finally, ANCA-associated glomerulonephritis is a rare complication of the disorder. In spite of treatment with ACE inhibitors, 20-50% of patients with renal crisis progress to end-stage renal disease. In the absence of a specific therapy, there is accumulating evidence supporting the effectiveness of prostacyclin derivatives, antifibrotic and immunosuppressive drugs. The evidence is strong that the ACE inhibitors that are used in renal crisis are disease modifying. In our series including 193 patients with systemic sclerosis, renal involvement was observed in 19 patients; 11 presented renal crisis (hypertensive in 8; normotensive in 3); 5 had chronic nephropathy; 2 developed penicillamine-induced nephrotic syndrome, and 1 ANCA-associated glomerulonephritis. Renal disease occurs in a minority of patients with systemic sclerosis, and may have a variable clinicopathological picture. As renal involvement is associated with a worse prognosis, careful monitoring of blood pressure, urine chemistry and renal function is required, particularly in patients with diffuse skin disease.

Familial aggregation of primary glomerulonephritis in an Italian population isolate: Valtrompia study.

Hereditary factors are suspected to contribute to the pathogenesis of sporadic primary glomerulonephritis, but their contribution is difficult to delineate in the general population. We studied the prevalence of primary glomerulonephritis in an isolated population from the extreme northern Valtrompia valley, Northern Italy. Investigation of medical records, community urinary screening program and molecular characterization of the population's ancestry were performed; genealogies of affected individuals were researched. Forty-three patients with primary glomerulonephritis were identified: 25 had biopsy-proven disease (11 immunoglobulin A (IgA) nephropathy; eight mesangial proliferative glomerulonephritis without IgA deposits; four focal segmental glomerular sclerosis; two membranous nephropathy), and 18 had clinical glomerulonephritis. All 43 patients originated from three mountain villages (Collio, San Colombano, and Bovegno). In contrast, we found only four cases of primary glomerulonephritis in two nearby villages (Pezzaze and Tavernole) that shared similar population histories and lifestyles, demonstrating heterogeneity of risk factors for glomerulonephritis (P=3 x 10(-5)). All 43 affected individuals could be traced back to common ancestors (XVI-XVII centuries), enabling the construction of three large pedigree including three parent-child affected pairs and five affected siblings pairs. Molecular data showed lower genetic diversity and increased inbreeding in the Valtrompia population compared to the control population. Molecular and genealogical evidence of limited set of founders and the absence of shared nephritogenic environmental factors suggest that our patients share a common genetic susceptibility to the development of primary glomerulonephritis. Further molecular study of our families will offer the possibility to shed light on the genetic background underlying these glomerular disorders.

Selection criteria for pre-operative endoscopic retrograde cholangiography and endoscopic-laparoscopic treatment of biliary stones.

OBJECTIVE: Pre-operative endoscopic retrograde cholangiography (ERCP) prior to laparoscopic cholecystectomy (LC) is the most common treatment of gallbladder and common bile duct (CBD) stones. In this study we evaluate our selection criteria for pre-operative ERCP and the results of endoscopic-laparoscopic treatment in patients with CBD stones. DESIGN: Consecutive adult patients admitted to the department of surgery because of symptomatic cholelithiasis were included in a prospective open trial. PARTICIPANTS: Between January 1996 and December 1996, 841 patients underwent LC at our hospital. ERCP pre-LC was performed in 95 of the 841 patients, on the basis of our selection criteria. INTERVENTIONS: The indication to perform ERCP was suggested by a dilatated CBD (> 10 mm) or ductal stones, abnormal serum liver tests, persisting for more than 3 days, jaundice, cholangitis or pancreatitis. Twelve months after surgery, all patients were contacted by telephone to exclude symptoms related to residual stones. RESULTS: Cannulation of the CBD was successful in 94 of 95 patients submitted to pre-LC ERCP. CBD stones were found in 87 patients (95.6%) in 22 of whom (25.2%) they were in the form of small stones or sludge. In only three of 94 patients (3.2%) no alterations of the CBD or papilla were found. Complications occurred in eight of 98 patients (in five after endoscopic sphincterotomy (ES), and in three after LC). CONCLUSIONS: Pre-operative ES in selected patients with coexisting gallbladder and CBD stones has been a good approach and the criteria that we used for selection of patients to be submitted to pre-operative ERCP/ES seem to be effective.

Is endoscopy useful for early diagnosis of ischaemic colitis after aortic surgery? Results of a prospective trial.

BACKGROUND: Ischaemic colitis is an infrequent, but potentially fatal, complication of abdominal aortic surgery. Its presentation is often underestimated on account of a paucity of symptoms, thus the real incidence of ischaemic colitis may be higher. AIM: To determine the prognostic value and sensitivity of endoscopy, early postoperative endoscopic findings were evaluated. METHODS: Over a period of three years a prospective study was undertaken in a consecutive series of 105 patients (mean age 68.9 years, range 51-85) undergoing routine rectosigmoidoscopy within 72 hours of aortic reconstructive surgery. RESULTS: Colonic ischaemia was found in 12 patients (11.4%); five had endoscopic evidence of mild ischaemic colitis, ulcerations were identified in five and diffuse superficial necrosis in two. Seven of the 12 patients were symptomatic. Laparotomy was never deemed necessary and all patients were successfully treated with a conservative regimen. There were no deaths. Elective reconstruction or urgent procedure did not correlate with the development of colonic ischaemia, nor did duration of aortic cross-clamp time, patency of the inferior mesenteric artery and its possible ligation or reimplantation or patency of the hypogastric arteries. CONCLUSIONS: Rectosigmoidoscopy is effective for early diagnosis of ischaemic colitis. Early endoscopy should be routinely performed only for patients in whom impaired blood flow is suspected on the basis of the intraoperative objective assessment of the colon and in presence of symptoms.