Role of interfaces on the stability and electrical properties of Ge2Sb2Te5 crystalline structures.

GeSbTe-based materials exhibit multiple crystalline phases, from disordered rocksalt, to rocksalt with ordered vacancy layers, and to the stable trigonal phase. In this paper we investigate the role of the interfaces on the structural and electrical properties of Ge2Sb2Te5. We find that the site of nucleation of the metastable rocksalt phase is crucial in determining the evolution towards vacancy ordering and the stable phase. By properly choosing the substrate and the capping layers, nucleation sites engineering can be obtained, thus promoting or preventing the vacancy ordering in the rocksalt structure or the conversion into the trigonal phase. The vacancy ordering occurs at lower annealing temperatures (170 °C) for films deposited in the amorphous phase on silicon (111), compared to the case of SiO2 substrate (200 °C), or in presence of a capping layer (330 °C). The mechanisms governing the nucleation have been explained in terms of interfacial energies. Resistance variations of about one order of magnitude have been measured upon transition from the disordered to the ordered rocksalt structure and then to the trigonal phase. The possibility to control the formation of the crystalline phases characterized by marked resistivity contrast is of fundamental relevance for the development of multilevel phase change data storage.

Coalescence of silver clusters by immersion in diluted HF solution.

The galvanic displacement deposition of silver on H-terminated Si (100) in the time scale of seconds is instantaneous and characterized by a cluster density of 10(11)-10(12) cm(-2). The amount of deposited Ag follows a t(1/2) dependence in agreement with a Cottrell diffusion limited mechanism. At the same time, during the deposition, the cluster density reduces by a factor 5. This behavior is in contrast with the assumption of immobile clusters. We show in the present work that coalescence and aggregation occur also in the samples immersed in the diluted hydrofluoric acid (HF) solution without the presence of Ag(+). Clusters agglomerate according to a process of dynamic coalescence, typical of colloids, followed by atomic redistribution at the contact regions with the generation of multiple internal twins and stacking-faults. The normalized size distributions in terms of r/rmean follow also the prediction of the Smoluchowski ripening mechanism. No variation of the cluster density occurs for samples immersed in pure H2O solution. The different behavior might be associated to the strong attraction of clusters to oxide-terminated Si surface in presence of water. The silver clusters are instead weakly bound to hydrophobic H-terminated Si in presence of HF. HF causes then the detachment of clusters and a random movement on the silicon surface with mobility of about 10(-13) cm(2)/s. Attractive interaction (probably van der Waals) among particles promotes coarsening.

Total mesorectal excision with radiofrequency in rectal cancer: open versus laparoscopy approach.

AIM: The aim of this study was to compare the safety, efficacy and oncologic results in the low rectal resection with total mesorectal excision with radiofrequency (Ligasure™, Covidien, Boulder, CO, USA) in laparoscopic surgery. METHODS: From July 2005 to December 2008, 227 patients underwent colorectal resection for cancer at S. Martino Hospital in Genoa. Sixty-one patients underwent curative rectal resection for mid or low rectal cancer using Ligasure™ device applied on smaller vessels and for the execution of total mesorectal excision. Forty-six patients underwent open laparotomy (OL), 15 laparoscopic surgery. There were no differences concerning demographics data and diagnosis, but only regarding staging (P=0.009). Primary goal was to evaluate major complications, operating time, hospital stay, distal margin of the tumor and number of nodes harvested in specimen. Secondary goal was to assess the average time of survival in the short period. RESULTS: The mean operative times were shorter in the OL group (188 vs. 246 min) overall. This difference was significant (P=0.004). In particular two parameters of specimens were analyzed: the total number of nodes and distal clearing from cancer, excluding abdominoperineal resection. An average number of 16.6 nodes in the OL group and 13.9 in the VL group (P=ns) were detected; mean distal clearing in the OL group was 30.7 mm and 48.1 mm in the VL group (P=ns). There were no differences concerning major complications in either group. The hospital stay in the VL group was shorter than in the OL group, but the differences were not significant. CONCLUSION: The Ligasure™ device does not reduce operating time in laparoscopy rectal cancer resection but it allows to get correct oncologic results in patients submitted to total mesorectal excision.

Gastric Abrikosoff tumor (granular cell tumor): case report.

Granular Cells Tumor (GCT), also called Abrikosoff tumor, is very uncommon lesion of neural derivation. It is characterized by the presence of granular cell; benign and malignamt counterparts are known, even if the second ones are rare. It has a slight predominance in female sex and black race; the age range is wide, with peak between fourth and sixth decades of life. Any localisation is possible, although surface lesions (head, neck, trunk, extremities) are far more common than visceral ones (esophagus, stomach, small and large bowel, larynx, bronchi, gallbladder and biliary tract). Surgical en-block excision is curative for both benign an malignant forms. Radiotherapy and chemotherapy are not effective. We report the case of a 45 year old man who had a cytologic diagnosis of fusocellular stromal tumor of the gastric fundus during examination for gastritis. He underwent a wedge resection of the gastric wall: at the histological examination neoplastic cells had a granular cytoplasm and immunoassay was positive for S100 protein, PGP 9.5 and NSE. Complete excision guarantees from recurrence and metastases: however a long term endoscopic follow-up is necessary.

Survival in surgical palliative resection of stage IV colorectal cancer: short term results in a single institution.

AIM: In this study, we analyze clinical parameters, survival and possible advantage of surgery in patients affected by symptomatic Dukes D colorectal cancer. METHODS: From July 2005 to December 2008 at our Oncological Surgery Unit we treated 69 symptomatic stage IV CRC, 46 of them resected at our Oncological Surgical Unit. Clinical variables were tested for their relationship to survival in a univariate prognostic analysis and revealed the interaction of the prognostic factors. RESULTS: In symptomatic stage IV CRC with non-curable resection, the most robust univariate predictor for poor prognosis was impossibility to cancer resection. It is associated with significative decrease of survival also in the short term. In our series we do not observe correlation between poor prognosis and age, gender, localisation of tumor, depth of invasion, 19.9 and surgeons. CEA more than 100 microg/L and impossibility to adiuvant therapy have a significative role and are associated with poor prognosis. CONCLUSION: Our results suggested that impossibility to perform cancer resection is associated with poor prognosis in symptomatic stage IV CRC and worse survival also in the short term.

[Leakage of colorectal anastomosis after neoadjuvant therapy with bevacizumab. Case report]. / Deiscenza di anastomosi colorettale dopo terapia neoadiuvante con bevacizumab. Case report.

BACKGROUND: Despite progresses achieved in last decades in treatment of rectal cancer, anastomotic leakage remains the main complication. PATIENTS AND METHODS: We report two cases of patients affected by distal rectal cancer. Both patients received neoadjuvant therapy according to ROCHE ML 18522 experimental protocol (Xeloda, Avastin and radiotherapy). After about respectively one and two months after anterior resection of the rectum, with transanal anastomosis and temporary colostomy, presacral abscess occurred. Patients were hospitalized and started antibiotic therapy. In one case it was necessary TC-guided drainage placement. RESULTS: Both patients had a favourable course and, after respectively 6 months and 1 year, underwent closure of colostomy. DISCUSSION: "Spontaneous" gastrointestinal microperforation (small leakage) is reported during treatment with bevacizumab, a monoclonal antibody against Vascular Endothelial Growth Factor (VEGF), also in patients with non gastrointestine tumours. Probably this results from inhibition of neoangiogenesis induced. CONCLUSIONS: Surgeons have to pay attention to adverse effects of combined neoadjuvant treatment of rectal cancer, considering temporary colostomy in presence of particular risk factors.

Factors predicting survival in surgical palliative resection of stage IV colorectal cancer.

AIM: Colorectal cancer (CRC) harbors accumulated genetic alterations with cancer progression, which results in uncontrollable disease. To regulate the most malignant CRC, we have to know the most dismal phenotype of stage IV disease. METHODS: A retrospective review of our Oncological Surgical Unit was performed (from 2005 to 2008) to extract the 52 resected stage IV CRC. Clinical variables were tested for their relationship to survival in a univariate prognostic analysis and revealed the interaction of the prognostic factors. RESULTS: In stage IV CRC with noncurable resection, the most robust univariate predictors for poor prognosis were preoperative high value of CEA. In our series we did not observe correlation between poor prognosis and depth of invasion, age, gender, pathologic lymph node metastasis status, Ca 19.9 and postoperative therapy. The mean average survival rate was 10.9 months. CONCLUSIONS: Our results suggested that only preoperative value CEA is associated with poor prognosis in stage IV CRC.

Lymphadenectomy in elective and urgency surgery for resective colorectal cancer.

AIM: The aim of this study was to analyze the factors affecting the number of lymph nodes examined in colorectal cancer specimens after elective or urgent surgery on the current clinical practice in our surgical unit. METHODS: The authors considered 120 patients who had undergone surgery for colorectal carcinoma from July 2005 to December 2007 divided into two groups, 102 elective oncologic resections (group A) and 18 performed in emergency (group B). All patients underwent laparotomic colorectal resection. The groups were similar in age, weight and body mass index, different in gender e in cancer stage. The authors analyze prognostic differences in number of examined lymph nodes and factors involved in differences between groups. RESULTS: There were no statistically significative differences in number of nodes harvested in specimen (15.85+/-8.17, CI 95% 14.25-17.46 for group A and 13.83+/-6.56, CI 95% 10.57-17.09 for group B, P-value 0.36). Operating time was shorter in group B (P-value 0.012). We not observed differences between groups in survival rate (P-value 0.62). CONCLUSIONS: The results of the study suggest that a correct lymphadenectomy and an adequate lymph node harvest in colorectal cancer surgery is essential also in resections performed in urgency, to allow a correct staging and an accurate selection of patients for adjuvant chemotherapy, with improvement of results at follow-up.

Screening length and quantum capacitance in graphene by scanning probe microscopy.

A nanoscale investigation on the capacitive behavior of graphene deposited on a SiO2/n(+) Si substrate (with SiO2 thickness of 300 or 100 nm) was carried out by scanning capacitance spectroscopy (SCS). A bias V(g) composed by an AC signal and a slow DC voltage ramp was applied to the macroscopic n(+) Si backgate of the graphene/SiO(2)/Si capacitor, while a nanoscale contact was obtained on graphene by the atomic force microscope tip. This study revealed that the capacitor effective area (A(eff)) responding to the AC bias is much smaller than the geometrical area of the graphene sheet. This area is related to the length scale on which the externally applied potential decays in graphene, that is, the screening length of the graphene 2DEG. The nonstationary charges (electrons/holes) induced by the AC potential spread within this area around the contact. A(eff) increases linearly with the bias and in a symmetric way for bias inversion. For each bias V(g), the value of A(eff) is related to the minimum area necessary to accommodate the not stationary charges, according to the graphene density of states (DOS) at V(g). Interestingly, by decreasing the SiO(2) thickness from 300 to 100 nm, the slope of the A(eff) versus bias curve strongly increases (by a factor of approximately 50). The local quantum capacitance C(q) in the contacted graphene region was calculated starting from the screening length, and the distribution of the values of C(q) for different tip positions was obtained. Finally the lateral variations of the DOS in graphene was determined.

Total mesorectal excision with radiofrequency in rectal cancer.

AIM: The aim of this study was to compare the safety, the efficacy and the oncologic results in rectal cancer with total mesorectal excision using Ligasure (LS), a modern bipolar vessel sealing system, with monopolar electrocoagulation or stitches (ME). METHODS: From July 2005 to December 2007 one hundred twenty-nine patients underwent colon resection for cancer at the San Martino Hospital of Genoa (Italy); 43 patients underwent rectal resection. All patients underwent laparotomy rectal resection with total mesorectal excision; 9 (21%, group LS) underwent total mesorectal excision with radiofrequency, 34 (79%, group ME) with monopolar electrocoagulations, vessels ligation or stitches. Patients of group LS were similar to patients of group ME in age, gender, weight and body mass index. Cancer stage was for group A 3 stage B, 5 stage C and 1 stage D, for group B 4 stage A, 15 stage B, 8 stage C, 6 stage D and 1 non-staged tumor. RESULTS: There were no differences in intraoperative or postoperative complications. Operating time was similar in both group. Oncological results was similar in both groups. The major cost in group LS were attributable to cost of service. CONCLUSION: The Ligasure device does not reduce operating time in laparotomy rectal cancer resection but permit correct oncological results in patients submitted to total mesorectal excision. The costs of device reserved its use to surgery of low-rectal cancer or laparoscopic approach.

A 12-year preventive program for beta-thalassemia in Northern Sardinia.

From 1980 to 1991, 6.3% of the adult population of the province of Sassari, Northern Sardinia, underwent voluntary beta-thalassemia screening. Of the 28,000 subjects examined, 15.7% proved to be heterozygotes for beta-thalassemia. In addition, the screening of 7500 students in 26 villages in Sassari province fixed the frequency of beta-thalassemia in this part of Sardinia at 10.4%. Of the 539 couples at risk to be expected from this figure, the screening detected 43% (234). The data suggest that inductive screening played a major role in the efficiency of this preventive beta-thalassemia program. Follow up of 221 pregnancies found to be at risk for homozygous beta-thalassemia and referred to the Antenatal Diagnosis Service, Cagliari, Southern Sardinia, showed that antenatal diagnosis was carried out in 80% of them. The overall percentage of couples refusing antenatal diagnosis was 10.8%, but over the years the acceptance rate for the procedure increased from 87% to 96%. Atypical hematological findings in 1.5% of 468 members of the couples at risk required globin chain synthesis and molecular analyses to define the precise beta-thalassemia genotype. Heterogeneous "mild" beta-thalassemia mutations as well as coexisting delta-thalassemia were found in silent type I and type II beta-thalassemia carriers which, without chain synthesis and DNA investigations, would have escaped detection.

A novel Mediterranean "delta beta-thalassemia" determinant containing the delta (+) 27 and beta (0) 39 point mutations in cis.

The term delta beta-thalassemia with normal HbF has been recently proposed to define heterogenous delta and beta globin gene molecular defects involving the same chromosome in cis. Here, we describe a Sardinian family in which three members showing microcytosis, border-line HbA2 levels and normal HbF proved to be heterozygotes for delta(+) 27 and beta(0) 39 point mutations in cis by allele specific oligonucleotide hybridization as well as by ECO 0 109 I endonuclease digestion and electrophoresis. As some of these beta-thalassemia carriers shows normal HbA2 levels, knowledge of the molecular basis of this novel delta beta-thalassemia silent phenotype would be useful in thalassemia screening and genetic counselling.

[Current views of thalassemia intermedia]. / Vedute attuali sulla talassemia intermedia.

Recently the molecular bases of thalassemia intermedia have been elucidated in several populations. In general this attenuated, non-transfusion dependent form of homozygous beta-thalassemia is mainly determined by a) the co-inheritance of deletion alpha-thalassemia; b) the presence of the so-called mild beta-thalassemia mutations; and more rarely, c) the inheritance of genetic conditions able to enhance the gamma-globin chain expression in adult life. Although there are several complex genetic and acquired interactions involved in the wide clinical heterogeneity of thalassemia intermedia, data in Italians indicate a definite genotype-phenotype relationship in conditions such as the co-inheritance of at least two alpha-thalassemia genes in severe and mild homozygous beta-thalassemia; the molecular homozygosity or double heterozygosity for the -87, -101 and IVS1(nt6) beta(+)-thalassemia mutations; and the coexistence of structural gamma-globin gene defects, i.e. Sicilian and Sardinian delta beta-thalassemias, deletional and non-deletional hereditary persistence of fetal hemoglobin and the polymorphism for the -158 XmnI G gamma restriction site. Thalassemia intermedia resulting from the inheritance in heterozygous beta-thalassemia of triple alpha-globin gene complex or the presence of dominant beta-thalassemia is also described and the role of these new informations in genetic counselling is discussed.

Haematological phenotypes in a family with triplicated alpha-globin gene, beta zero 39 and delta+27 thalassaemia mutations.

In this paper we report an unusual Sardinian family, in which the heterozygosity for beta zero 39-thalassaemia and for triple alpha-globin gene complex have been found in two members: the former showing a high HbA2 mild thalassaemia intermedia syndrome, the latter, her daughter, showing a normal HbA2 thalassaemia trait. Molecular analysis revealed the daughter to also be a carrier of a delta+27-thalassaemia point mutation, which in trans to the beta zero 39 defect invariably normalizes the HbA2 levels.