Endosonographic features of esophageal granular cell tumors

BACKGROUND AND STUDY AIMS: Granular cell tumors of the esophagus are rare tumors. A definite diagnosis is achieved by endoscopic biopsies in only 50% of cases. Endoscopic ultrasonography (EUS) is the best procedure in the evaluation of upper gastrointestinal tract submucosal tumors. The aim of this study was to describe the endosonographic findings of esophageal granular cell tumors. METHODS: From January 1989 to March 1994, 15 patients with 21 granular cell tumors which had negative biopsies were examined by EUS (Olympus GF UM3 or GF UM20,7,5 and 12 MHz). In five cases, the tumor was also studied with a 20 MHz Olympus miniprobe. The final histological diagnoses were obtained by subsequent endoscopic snare resection in 20 cases and surgically in one case. RESULTS: The endosonographic features (with the GF UM3 or GF UM20) of esophageal granular cell tumors were: a) a tumor size of less than 2 cm in 95% of cases; b) an hypoechoic solid pattern in 100% of cases; c) a tumor arising in the inner layers in 95% (second echo-poor layer n=15; third echo-rich layer n=5). In one case, the endosonographic finding was transmural malignant infiltration of the esophageal wall (histologically confirmed). CONCLUSION: When a granular cell tumor of the esophagus is suspected, EUS can show the inner layer location of the tumor and thus contribute to planning the endoscopic resection or follow up. When the tumor also invades the outer layers, EUS can contribute to planning the surgical resection.     

On the Use of the Flickermeter to Limit Low-Frequency Interharmonic Voltages

The possibility of using the IEC flickermeter for the assessment of the limits of low frequency interharmonic voltages is critically analyzed. The response of flickermeters to interharmonic components is analytically investigated, obtaining approximation formulas for the calculation of Pst in the presence of couples of components at frequencies that are symmetric with reference to the fundamental and in the presence of one or more single components. The instrument characteristics and limitations are also highlighted, using the results obtained from a numerical implementation of the IEC flickermeter. Finally, the general problem of the limits of low frequency interharmonic voltages is discussed and practical solutions are proposed.     

Gluten-free diet induces regression of T-cell activation in the rectal mucosa of patients with celiac disease

OBJECTIVE: An increase in the number of intraepithelial lymphocytes (IEL) in the rectal epithelium of patients with active celiac disease has been described. No data are available about how they vary during a gluten-free diet. The aim of the study was to assess the effect of a gluten-free diet on T-cell activation in the rectal mucosa of adult patients with celiac disease. METHODS: Frozen duodenal and rectal biopsies were available in four celiac patients (one male, three female, mean age 39 yr) both before and after 7 to 24 months on a gluten-free diet. Biopsy samples were stained using monoclonal antibodies directed against CD3, betaF1, TcRdelta1, CD25, and HLADR. Numbers of IEL were estimated by counting the peroxidase-stained cells per 100 epithelial cells. Four patients without histological abnormalities were used as control subjects. RESULTS: In the four patients with active celiac disease but in none of the controls, CD25 was expressed by both duodenal and rectal lamina propria cells and HLADR was expressed by duodenal (4/4) and rectal (2/4) epithelial cells. In addition, two patients with active celiac disease had features of lymphocytic colitis, i.e., >20 IEL per 100 epithelial cells. After a gluten-free diet, the mean number of rectal CD3+ betaF1+ IEL decreased (9% vs 21%) and the expression of CD25 and HLADR was no longer present. These changes mirrored those found in the small intestinal biopsies. CONCLUSION: These results suggest that in celiac disease, gluten-driven T-cell activation is not restricted to the proximal part of the intestine but is present on the whole intestinal length. Assessment of the effectiveness of a gluten-free diet through rectal biopsies warrants investigation, as it could lessen discomfort for patients and prove more cost-effective.     

Nonlinear Versus Linear Learning Devices: A Procedural Perspective

We provide a discussion of bounded rationality learning behind traditional learning mechanisms, i.e., Recursive Ordinary Least Squares and Bayesian Learning . These mechanisms lack for many reasons a behavioral interpretation and, following the Simon criticism, they appear to be substantively rational. In this paper, analyzing the Cagan model, we explore two learning mechanisms which appear to be more plausible from a behavioral point of view and somehow procedurally rational: Least Mean Squares learning for linear models and Back Propagation for Artificial Neural Networks . The two algorithms look for a minimum of the variance of the error forecasting by means of a steepest descent gradient procedure. The analysis of the Cagan model shows an interesting result: non-convergence of learning to the Rational Expectations Equilibrium is not due to the restriction to linear learning devices; also Back Propagation learning for Artificial Neural Networks may fail to converge to the Rational Expectations Equilibrium of the model.     

Complexity of points-to analysis of Java in the presence ofexceptions

At each program point, points-to analysis for statically typed object oriented programming languages (e.g., Java, C++) determines those objects to which a reference may refer (or a pointer may point) during execution. Points-to analysis is necessary for any semantics based software tools for object oriented systems. Our new complexity results for points-to analysis distinguish the difficulty of intraprocedural and interprocedural points-to analyses for languages with combinations of single-level types (i.e., types with data members only of primitive type), exceptions with or without subtyping, and dynamic dispatch. Our results include: 1) the first polynomial-time algorithm for points-to analysis in the presence of exceptions that handles a robust subset of Java without threads and can be applied to C++; 2) proof that the above algorithm is safe, in general, and provably precise on programs with single-level types and exceptions without subtyping, but not dynamic dispatch, thus, this case is in P; 3) proof that an interprocedural points-to analysis problem with single-level types and exceptions with subtyping, but without dynamic dispatch, is PSPACE-hard, while the intraprocedural problem is PSPACE-complete. Other complexity characterizations of points-to analysis in programs without exceptions are presented, including an algorithm with worst-case bound of O(n⁵ ), which improves over the O(n⁷) worst-case bound achievable from previous approaches of T. Reps et al. (1995) and W.A. Landi and B.G. Ryder (1991)     

Nano-to-macroporous TiO2 (anatase) by cold sintering process

Cold Sintering Process (CSP) was applied on commercial nanopowders to produce nanostructured TiO₂ anatase with nano-to-macro porosity. Nanoporous TiO₂ based materials were obtained by applying CSP at 150 °C and pressures up to 500 MPa on three TiO₂ nanopowders with different specific surface area (s.s.a. = 50, 90 and 370 m²/g), using water as transient aqueous environment. Although TiO₂ is insoluble in water, a density of 68% and s.s.a. = 117 m²/g were achieved from the powder with the highest specific surface area. A post annealing process at 500 °C increased the density up to 73% with a s.s.a. = 59 m²/g, and the crystallites dimensions passed from 110 Å in the powder to 130 Å in CSP material and 172 Å after post annealing. Finally, macroporosity was produced by using thermoplastic polymer beads as sacrificial templates within TiO₂ nanopowder during CSP, followed by a debonding at 500 °C.     

Effect of fermentation temperature on microbial population evolution using culture-independent and dependent techniques

The population dynamics of micro-organisms during grape-must fermentation has been thoroughly studied. However, the main approach has relied on microbiological methods based on plating. This approach may overlook micro-organisms that (i) grow slowly or do not grow well on artificial media or (ii) whose population size is small enough to be detected by regular sampling. Culture-independent methods have been used and compared with the traditional plating method during wine fermentations performed at two different temperatures (13 °C and 25 °C). These methods include a qualitative technique, the DGGE; a semi-quantitative technique, the direct cloning of amplified DNA; and a quantitative technique, the QPCR. The biodiversity observed in the must and at the beginning of fermentation was much higher when DGGE or direct cloning were used. Quantification of the most frequent non-Saccharomyces yeast, Hanseniaspora uvarum and Candida zemplinina, showed that they survived throughout the fermentation process and, specifically, it revealed the quantitatively relevant presence of C. zemplinina until the end of fermentation.     

Atomic data and spectral line intensities for Ca XVII

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ca XVII. The configurations used are 2s², 2s2p, 2p², 2l3l^′, 2l4l^′ and 2s5l^′, with l=s,p, and l^′=s,p,d giving rise to 92 fine-structure levels in intermediate coupling. Collision strengths are calculated at seven incident energies (15, 30, 75, 112.5, 150, 187.5 and 225 Ry) for the transitions within the three lowest configurations corresponding to the 10 lowest energy levels, and at five incident energies (75, 112.5, 150, 187.5 and 225 Ry) for transitions between the lowest five levels and the n=3,4,5 configurations. Calculations have been carried out using the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates of the present work, and R-Matrix results for the 2s², 2s2p, 2p² configurations available in the literature, statistical equilibrium equations for level populations are solved at electron densities covering the range of at an electron temperature of logT_e(K)=6.7, corresponding to the maximum abundance of Ca XVII. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.     

Representation of High Resolution Images from Low Sampled Fourier Data: Applications to Dynamic MRI

In this work we propose the use of B-spline functions for the parametric representation of high resolution images from low sampled data in the Fourier domain. Traditionally, exponential basis functions are employed in this situation, but they produce artifacts and amplify the noise on the data. We present the method in an algorithmic form and carefully consider the problem of solving the ill-conditioned linear system arising from the method by an efficient regularization method. Two applications of the proposed method to dynamic Magnetic Resonance images are considered. Dynamic Magnetic Resonance acquires a time series of images of the same slice of the body; in order to fasten the acquisition, the data are low sampled in the Fourier space. Numerical experiments have been performed both on simulated and real Magnetic Resonance data. They show that the B-splines reduce the artifacts and the noise in the representation of high resolution Magnetic Resonance images from low sampled data. This work was supported by the Italian MIUR project Inverse Problems in Medical Imaging 2004–2006 (grant no 2004015818). Germana Landi received the BS degree in Mathematics from the University of Bologna in 1997 and the Ph.D. degree in Computational Mathematics from the University of Padova in 2000. She is currently a postdoctoral researcher in Numerical Analysis at the Department of Mathematics of the University of Bologna. Her research interests include medical imaging and inverse ill-posed problems. Elena Loli Piccolomini received the BS degree in Mathematics from the University of Bologna in 1988. She is an associate professor in Numerical Analysis at the Department of Mathematics of the University of Bologna. Her research interests include numerical methods for the regularization of discrete ill-posed problems with application to medical imaging (MR, TAC, SPECT, PET).     

Spontaneous intracranial hypotension: report of four cases and review of the literature

Spontaneous intracranial hypotension is an unusual syndrome of postural headache and low cerebrospinal fluid pressure without an established cause. We present four cases, analyze those previously reported in the literature, examine the MRI, CT, angiographic and cisternographic finding and discuss the clinical picture, proposed pathophysiologic mechanisms and potential treatment.