Current–voltage and noise characteristics of reverse-biased Au/n-GaAs Schottky diodes with embedded InAs quantum dots

Arpatzanis, N,Tassis, D H,Dimitriadis, C A,Charitidis, C,Song, J D,Choi, W J,Lee, J I Institute of Physics 2007 Semiconductor science and technology Vol.22 No.10

<P>Schottky contacts on n-type GaAs with embedded InAs quantum dots (QDs) were studied by current–voltage (<I>I</I>–<I>V</I>) and low-frequency noise measurements. For comparison, diodes not containing QDs were investigated as reference devices. A wide distribution of the ideality factor was observed, correlated with the level of the leakage current. Reverse <I>I</I>–<I>V</I> characteristics on the logarithmic scale indicate that the space-charge limited current dominates the carrier transport in these diodes. In all diodes, the reverse current noise spectra show 1/<I>f</I> behaviour, attributed to traps uniformly distributed in energy within the band-gap of the GaAs capping layer. Depth profiling measurements of the 1/<I>f</I> noise power spectral density demonstrate the impact of the QDs on these traps. In diodes containing QDs, in addition to the 1/<I>f</I> noise, a generation–recombination noise is found originating from a deep trap level localized in the vicinity of the QD plane.</P>

Tumor Angiogenesis: Initiation and Targeting -Therapeutic Targeting of an FGF-Binding Protein, an Angiogenic Switch Molecule, and Indicator of Early Stages of Gastrointestinal Adenocarcinomas

Elena Tassi,Anton Wellstein 대한암학회 2006 Cancer Research and Treatment Vol.38 No.4

Tumor angiogenesis has been related to the initiation as well as progression toward more aggressive behavior of human tumors. In particular, the activity of angiogenic factors is crucial for tumor progression. We previously characterized a secreted fibroblast growth factor-binding protein (FGF-BP) as a chaperone molecule, which binds to various FGFs, enhances FGF-mediated biochemical and biologic events and importantly is a crucial rate-limiting factor for tumor-dependent angiogenesis. We generated monoclonal antibodies that target FGF-BP protein and used them as a tool to evaluate frequency and pattern of FGF-BP expression during the malignant progression of pancreas and colorectal carcinoma in archival tissue samples. We found that FGF-BP is dramatically upregulated during the initiation of colorectal and pancreatic adenocarcinoma. Crucial genetic events underlying the initiation and progression of colorectal and pancreatic adenocarcinoma with a particular focus on the modulation of angiogenesis and antiangiogenic therapies are discussed. We propose that the upregulation of the secreted FGF-BP protein during early phases of pancreas and colon cancer could make this protein a possible serum marker indicating the presence of high-risk premalignant lesions. Furthermore, the biological activity of FGF-BP is neutralized by monoclonal antibodies suggesting the potential for antibody-based therapeutic targeting. (Cancer Res Treat. 2006;38:189-197)

Whey Versus Soy Protein Diets and Renal Status in Rats

Virginia A. Aparicio,Elena Nebot,Mohamed Tassi,Daniel Camiletti-Moiron,Cristina Sanchez-Gonzalez,Jesus M. Porres,Pilar Aranda 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.9

Different dietary protein sources can promote different renal statuses. We examined the effects of whey protein (WP) and soy protein (SP) intake on plasma, urinary, and morphological renal parameters in rats. One hundred and twenty Wistar rats were randomly distributed into 2 experimental groups fed with either WP or SP diets over 12 weeks. These diets were based on commercial WP or SP isolates. The urinary calcium content was higher in the WP diet compared to the SP diet group (P < .001) whereas the urinary citrate level was lower (P < .001). The urinary pH was more acidic in the WP diet group compared to the SP diet group (P < .001); however, no differences were observed between the groups for any of the renal morphological parameters analyzed (all, P > .05) or other plasma renal markers such as albumin or urea concentrations. The increase of acid and urinary calcium and the lower urinary citrate level observed in the WP diet group could increase the incidence of nephrolithiasis compared to the SP diet group. Despite the WP showed poorer acid-base profile, no significant morphological renal changes were observed. These results suggest that the use of SP instead of WP appears to promote a more alkaline plasma and urinary profile, with their consequent renal advantages.

Aortic Stiffness in Patients with Deep and Lobar Intracerebral Hemorrhage: Role of Antihypertensive Drugs and Statins

Maurizio Acampa,Francesca Guideri,Rossana Tassi,Giuseppe Martini 대한뇌졸중학회 2015 Journal of stroke Vol.17 No.1

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Ischemic Stroke after Heart Transplantation

Maurizio Acampa,Pietro Enea Lazzerini,Francesca Guideri,Rossana Tassi,Giuseppe Martini 대한뇌졸중학회 2016 Journal of stroke Vol.18 No.2

Cerebrovascular complications after orthotopic heart transplantation (OHT) are more common in comparison with neurological sequelae subsequent to routine cardiac surgery. Ischemic stroke and transient ischemic attack (TIA) are more common (with an incidence of up to 13%) than intracranial hemorrhage (2.5%). Clinically, ischemic stroke is manifested by the appearance of focal neurologic deficits, although sometimes a stroke may be silent or manifests itself by the appearance of encephalopathy, reflecting a diffuse brain disorder. Ischemic stroke subtypes distribution in perioperative and postoperative period after OHT is very different from classical distribution, with different pathogenic mechanisms. Infact, ischemic stroke may be caused by less common and unusual mechanisms, linked to surgical procedures and to postoperative inflammation, peculiar to this group of patients. However, many strokes (40%) occur without a well-defined etiology (cryptogenic strokes). A silent atrial fibrillation (AF) may play a role in pathogenesis of these strokes and P wave dispersion may represent a predictor of AF. In OHT patients, P wave dispersion correlates with homocysteine plasma levels and hyperhomocysteinemia could play a role in the pathogenesis of these strokes with multiple mechanisms increasing the risk of AF. In conclusion, stroke after heart transplantation represents a complication with considerable impact not only on mortality but also on subsequent poor functional outcome.

Arterial Stiffness in Patients with Deep and Lobar Intracerebral Hemorrhage

Maurizio Acampa,Francesca Guideri,Ilaria Di Donato,Rossana Tassi,Giovanna Marotta,Giuseppe Lo Giudice,Paolo D’Andrea,Giuseppe Martini 대한뇌졸중학회 2014 Journal of stroke Vol.16 No.3

Background and Purpose Intracerebral hemorrhage (ICH) accounts for approximately 10% of stroke cases. Hypertension may play a role in the pathogenesis of ICH that occurs in the basal ganglia, thalamus, pons, and cerebellum, but not in that of lobar ICH. Hypertension contributes to decreased elasticity of arteries, thereby increasing the likelihood of rupture in response to acute elevation in intravascular pressure. This study aimed to evaluate arterial stiffness (using the arterial stiffness index [ASI]) in patients with deep (putaminal and thalamic) ICH in comparison with patients with lobar ICH. Methods We enrolled 64 patients (mean±SD age: 69.3±10.7 years; 47 men and 17 women) among 73 who referred consecutively to our department for intraparenchymal hemorrhage and underwent brain computed tomography (CT) and cerebral angio-CT. In all the subjects, 24-hour heart rates and blood pressures were monitored. The linear regression slope of diastolic on systolic blood pressure was assumed as a global measure of arterial compliance, and its complement (1 minus the slope), ASI, has been considered as a measure of arterial stiffness. Results In the patients with deep ICH, ASI was significantly higher than in the patients with lobar ICH (0.64±0.19 vs. 0.53±0.17, P=0.04). Conclusions Our results suggest that in deep ICH, arterial stiffening represents a possible pathogenetic factor that modifies arterial wall properties and contributes to vascular rupture in response to intravascular pressure acute elevation. Therapeutic strategies that reduce arterial stiffness may potentially lower the incidence of deep hemorrhagic stroke.

Stroke Etiology and Outcomes after Endovascular Thrombectomy: Results from the SITS Registry and a Meta-Analysis

Marius Matusevicius,Charith Cooray,Viiu-Marika Rand,Ana Paiva Nunes,Tiago Moreira,Rossana Tassi,Jose Antonio Egido,Jyrki Ollikainen,Guido Bigliardi,Staffan Holmin,Niaz Ahmed 대한뇌졸중학회 2021 Journal of stroke Vol.23 No.3

Background and Purpose The influence of stroke etiology on outcomes after endovascular thrombectomy (EVT) is not well understood. We aimed to investigate whether stroke etiology subgrouped as large artery atherosclerosis (LAA) and cardiac embolism (CE) influences outcomes in large artery occlusion (LAO) treated by EVT. Methods We included EVT treated LAO stroke patients registered in the Safe Implementation of Treatment in Stroke (SITS) thrombectomy register between January 1, 2014 and September 3, 2019. Primary outcome was successful reperfusion (modified Treatment in Cerebral Infarction 2b- 3). Secondary outcomes were symptomatic intracranial hemorrhage (SICH), 3-month functional independence (modified Ranking Scale 0–2) and death. Multivariable logistic regression models were used for comparisons. In addition, a meta-analysis of aggregate data from the current literature was conducted (PROSPERO, ID 167447). Results Of 7,543 patients, 1,903 (25.2%) had LAA, 3,214 (42.6%) CE, and 2,426 (32.2%) unknown, other, or multiple etiologies. LAA patients were younger (66 vs. 74, P<0.001) and had lower National Institutes of Health Stroke Scale score at baseline (15 vs. 16, P<0.001) than CE patients. Multivariable analyses showed that LAA patients had lower odds of successful reperfusion (odds ratio [OR], 0.70; 95% confidence interval [CI], 0.57 to 0.86) and functional independence (OR, 0.74; 95% CI, 0.63 to 0.85), higher risk of death (OR, 1.44; 95% CI, 1.21 to 1.71), but no difference in SICH (OR, 1.09; 95% CI, 0.71 to 1.66) compared to CE patients. The systematic review found 25 studies matching the criteria. The meta-analysis did not find any difference between etiologies. Conclusions From the SITS thrombectomy register, we observed a lower chance of reperfusion and worse outcomes after thrombectomy in patients with LAA compared to CE etiology, despite more favorable baseline characteristics. In contrast, the meta-analysis did not find any difference between etiologies with aggregate data.