MRI features indicative of permanent colon damage in ulcerative colitis: an exploratory study.

BACKGROUND AND AIMS: It is uncertain whether ulcerative colitis leads to accumulated bowel damage on cross sectional image. We aimed to characterize bowel damage in patients with ulcerative colitis using magnetic resonance imaging and determine its relation with duration of disease and the impact on patients' quality of life. METHODS: In this prospective study, subjects with ulcerative colitis in endoscopic remission underwent MRI without bowel cleansing and completed quality-of-life questionnaires. Subjects' magnetic resonance findings were analyzed considering normal values and thresholds determined in controls with no history of inflammatory bowel disease (n=40) and in patients with Crohn's disease with no history of colonic involvement (n=12). Subjects with UC were stratified according to disease duration (<7 years vs. 7‒14 years vs. >14 years). RESULTS: We analyzed 41 subjects with ulcerative colitis [20 women; Mayo endoscopic subscore 0 in 38 (92.7%) and 1 in 3 (7.3%)]. Paired segment-by-segment comparison of magnetic resonance findings in colonic segments documented of being affected by ulcerative colitis versus controls showed subjects with ulcerative colitis had decreased cross-sectional area (p≤0.0034) and perimeter (p≤0.0005), and increased wall thickness (p=0.026) in all segments. Colon damage, defined as wall thickness ≥3 mm, was seen in 22 (53.7%) subjects. Colon damage was not associated with disease duration or quality of life. CONCLUSIONS: Morphologic abnormalities in the colon were highly prevalent in patients with ulcerative colitis in the absence of inflammation. Structural bowel damage was not associated with disease duration or quality of life.

Diagnosis and treatment of hepatocellular carcinoma. Update of the consensus document of the AEEH, AEC, SEOM, SERAM, SERVEI, and SETH. / Diagnóstico y tratamiento del carcinoma hepatocelular. Actualización del documento de consenso de la AEEH, AEC, SEOM, SERAM, SERVEI y SETH.

Hepatocellular carcinoma (HCC) is the most common primary liver neoplasm and one of the most common causes of death in patients with cirrhosis of the liver. In parallel, with recognition of the clinical relevance of this cancer, major new developments have recently appeared in its diagnosis, prognostic assessment and in particular, in its treatment. Therefore, the Spanish Association for the Study of the Liver (AEEH) has driven the need to update the clinical practice guidelines, once again inviting all the societies involved in the diagnosis and treatment of this disease to participate in the drafting and approval of the document: Spanish Society for Liver Transplantation (SETH), Spanish Society of Diagnostic Radiology (SERAM), Spanish Society of Vascular and Interventional Radiology (SERVEI), Spanish Association of Surgeons (AEC) and Spanish Society of Medical Oncology (SEOM). The clinical practice guidelines published in 2016 and accepted as National Health System Clinical Practice Guidelines were taken as the reference documents, incorporating the most important recent advances. The scientific evidence and the strength of the recommendation is based on the GRADE system.

Imaging biomarkers for steatohepatitis and fibrosis detection in non-alcoholic fatty liver disease.

There is a need, in NAFLD management, to develop non-invasive methods to detect steatohepatitis (NASH) and to predict advanced fibrosis stages. We evaluated a tool based on optical analysis of liver magnetic resonance images (MRI) as biomarkers for NASH and fibrosis detection by investigating patients with biopsy-proven NAFLD who underwent magnetic resonance (MR) protocols using 1.5T General Electric (GE) or Philips devices. Two imaging biomarkers (NASHMRI and FibroMRI) were developed, standardised and validated using area under the receiver operating characteristic curve (AUROC) analysis. The results indicated NASHMRI diagnostic accuracy for steatohepatitis detection was 0.83 (95% CI: 0.73-0.93) and FibroMRI diagnostic accuracy for significant fibrosis determination was 0.85 (95% CI: 0.77-0.94). These findings were independent of the MR system used. We conclude that optical analysis of MRI has high potential to define non-invasive imaging biomarkers for the detection of steatohepatitis (NASHMRI) and the prediction of significant fibrosis (FibroMRI) in NAFLD patients.

Resonancia magnética para la detección no invasiva de la enfermedad microcirculatoria asociada a la vasculopatía de alotrasplante: validación de la determinación intracoronaria / Magnetic resonance for noninvasive detection of microcirculatory disease associated with allograft vasculopathy: intracoronary measurement validation

Introducción y objetivos. La vasculopatía del aloinjerto cardiaco afecta tanto al compartimento coronario epicárdico como al de la microcirculación. Se ha propuesto el uso de las técnicas de imagen de perfusión de la resonancia magnética como instrumento útil para la evaluación de la microcirculación, principalmente fuera del contexto del trasplante de corazón. La pendiente de velocidad del flujo-presión diastólica hiperémica instantánea, que es un índice de la fisiología intracoronaria, ha mostrado mejor correlación con el remodelado microcirculatorio en la vasculopatía del aloinjerto cardiaco que la de otros índices como la reserva de velocidad del flujo coronario. Con objeto de investigar el potencial de las técnicas de imagen de perfusión de resonancia magnética para detectar la presencia de remodelado microcirculatorio en la vasculopatía de aloinjerto cardiaco, se ha comparado los datos de perfusión de resonancia magnética con los índices fisiológicos intracoronarios invasivos, para estudiar la microcirculación en una población de pacientes con trasplante de corazón que presentaban una enfermedad macrovascular no obstructiva demostrada por la ecografía intravascular. Métodos. Se estudió a 8 pacientes con trasplante de corazón (media de edad, 61 ± 12 años; el 100% varones) que presentaban una vasculopatía del aloinjerto epicárdica definida por ecografía intravascular, estenosis coronarias no significativas y una resonancia magnética de estrés con dobutamina con evaluación visual del movimiento de la pared/perfusión negativa. Se determinaron los datos de perfusión de resonancia magnética cuantitativa en estrés y en reposo para establecer el índice de reserva de perfusión miocárdica, de manera no invasiva, y se determinaron cuatro índices fisiológicos intracoronarios evaluados de manera invasiva. Resultados. Los datos posprocesados mostraron una media del índice de reserva de perfusión miocárdica de 1,22 ± 0,27, mientras que la reserva de flujo fraccional, la reserva de velocidad del flujo coronario, la resistencia microvascular hiperémica y la pendiente de velocidad del flujo-presión diastólica hiperémica instantánea fueron de 0,98 ± 0,02, 2,34 ± 0,55, 2,00 ± 0,69 y 0,91 ± 0,65 cm/s/mmHg respectivamente. El índice de reserva de perfusión miocárdica presentó una correlación intensa tan solo con la pendiente de velocidad del flujo-presión diastólica hiperémica instantánea (r = 0,75; p = 0,033). Conclusiones. El índice de reserva de perfusión miocárdica obtenido a partir de la resonancia magnética de estrés con dobutamina completa resulta una técnica fiable para la detección no invasiva de la enfermedad coronaria microcirculatoria asociada a la vasculopatía de aloinjerto cardiaco (AU)

Introduction and objectives. Cardiac allograft vasculopathy affects both epicardial and microcirculatory coronary compartments. Magnetic resonance perfusion imaging has been proposed as a useful tool to assess microcirculation mostly outside the heart transplantation setting. Instantaneous hyperemic diastolic flow velocity-pressure slope, an intracoronary physiology index, has demonstrated a better correlation with microcirculatory remodelling in cardiac allograft vasculopathy than other indices such as coronary flow velocity reserve. To investigate the potential of magnetic resonance perfusion imaging to detect the presence of microcirculatory remodeling in cardiac allograft vasculopathy, we compared magnetic resonance perfusion data with invasive intracoronary physiological indices to study microcirculation in a population of heart transplantation recipients with macrovascular nonobstructive disease demonstrated with intravascular ultrasound. Methods. We studied 8 heart transplantation recipients (mean age, 61 [12] years, 100% male) with epicardial allograft vasculopathy defined by intravascular ultrasound, nonsignificant coronary stenoses and negative visually-assessed wall-motion/perfusion dobutamine stress magnetic resonance. Quantitative stress and rest magnetic resonance perfusion data to build myocardial perfusion reserve index, noninvasively, and 4 invasive intracoronary physiological indices were determined. Results. Postprocessed data showed a mean (standard deviation) myocardial perfusion reserve index of 1.22 (0.27), while fractional flow reserve, coronary flow velocity reserve, hyperemic microvascular resistance and instantaneous hyperemic diastolic flow velocity-pressure slope were 0.98 (0.02), cm/s/mmHg, 2.34 (0.55) cm/s/mmHg, 2.00 (0.69) cm/s/mmHg and 0.91 (0.65) cm/s/mmHg, respectively. The myocardial perfusion reserve index correlated strongly only with the instantaneous hyperemic diastolic flow velocity-pressure slope (r = 0.75; P = .033). Conclusions. Myocardial perfusion reserve index derived from a comprehensive dobutamine stress magnetic resonance appears to be a reliable technique for noninvasive detection of microcirculatory coronary disease associated with cardiac allograft vasculopathy (AU)

Magnetic Resonance for Noninvasive Detection of Microcirculatory Disease Associated With Allograft Vasculopathy: Intracoronary Measurement Validation.

INTRODUCTION AND OBJECTIVES: Cardiac allograft vasculopathy affects both epicardial and microcirculatory coronary compartments. Magnetic resonance perfusion imaging has been proposed as a useful tool to assess microcirculation mostly outside the heart transplantation setting. Instantaneous hyperemic diastolic flow velocity-pressure slope, an intracoronary physiology index, has demonstrated a better correlation with microcirculatory remodelling in cardiac allograft vasculopathy than other indices such as coronary flow velocity reserve. To investigate the potential of magnetic resonance perfusion imaging to detect the presence of microcirculatory remodeling in cardiac allograft vasculopathy, we compared magnetic resonance perfusion data with invasive intracoronary physiological indices to study microcirculation in a population of heart transplantation recipients with macrovascular nonobstructive disease demonstrated with intravascular ultrasound. METHODS: We studied 8 heart transplantation recipients (mean age, 61 [12] years, 100% male) with epicardial allograft vasculopathy defined by intravascular ultrasound, nonsignificant coronary stenoses and negative visually-assessed wall-motion/perfusion dobutamine stress magnetic resonance. Quantitative stress and rest magnetic resonance perfusion data to build myocardial perfusion reserve index, noninvasively, and 4 invasive intracoronary physiological indices were determined. RESULTS: Postprocessed data showed a mean (standard deviation) myocardial perfusion reserve index of 1.22 (0.27), while fractional flow reserve, coronary flow velocity reserve, hyperemic microvascular resistance and instantaneous hyperemic diastolic flow velocity-pressure slope were 0.98 (0.02), cm/s/mmHg, 2.34 (0.55) cm/s/mmHg, 2.00 (0.69) cm/s/mmHg and 0.91 (0.65) cm/s/mmHg, respectively. The myocardial perfusion reserve index correlated strongly only with the instantaneous hyperemic diastolic flow velocity-pressure slope (r=0.75; P=.033). CONCLUSIONS: Myocardial perfusion reserve index derived from a comprehensive dobutamine stress magnetic resonance appears to be a reliable technique for noninvasive detection of microcirculatory coronary disease associated with cardiac allograft vasculopathy.

Paroxysmal nocturnal hemoglobinuria: a single Spanish center's experience over the last 40 yr.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal disease. To date, many reviews and series have been described. We report the experience of our center by presenting a review of 56 PNH patient cases with an average age at diagnosis of 38 yr and follow-ups beginning at approximately 40 yr; the median survival rate was 11 yr. The average clonal size upon diagnosis was 48%, presenting a variable evolution. Thrombotic episodes and cancer were five each, and the main causes of death among our patients were equal at 8.9%. Radiological study by magnetic resonance imaging is presented as a fundamental technique for estimating the deposit of iron levels in the liver and kidney, as well as in some decisive cases at the start of eculizumab therapy. Sixteen patients have been treated with eculizumab so far in our series, and being a safe drug, it provides improvement in the patients' quality of life, and the disappearance of clinical symptoms, and avoids the emergence of new thrombosis.

Uso de la enterografía por resonancia magnética en el manejo de la enfermedad de Crohn de intestino delgado: primer año de experiencia / Using of magnetic resonance enterography in the management of Crohn's disease of the small intestine: first year of experience

Objetivo: describir la experiencia de dos centros terciarios durante el primer año de uso de la enterografía por resonancia magnética (enteroRM) para el manejo de la enfermedad de Crohn (EC): indicaciones e influencia en la toma de decisiones clínicas. Material y métodos: estudio descriptivo retrospectivo. Se incluyeron de forma consecutiva a pacientes a los que se realizaba una enteroRM. Se recogieron los datos epidemiológicos y clínicos de los pacientes, la indicación de la prueba y como influyó sobre la toma de decisiones clínicas en los 10 días posteriores a la realización de la prueba radiológica. Resultados: se realizaron 24 enteroRM por sospecha de EC y 126 por seguimiento clínico en pacientes con EC conocida: clínica suboclusiva en 53 (42%), monitorización de los tratamientos médicos en 34 (27%), completar el estudio por ileocolonoscopia incompleta en 16 (13%), estudio de extensión en intestino delgado en 15 (12%) y finalmente la sospecha de EC complicada en 8 pacientes (6%). La realización de la enteroRM influyó en el tratamiento en 83 (55,3%) pacientes. Dieciséis (10,7%) pacientes con inmunosupresores, 41 pacientes (27,3%) iniciaron o cambiaron de anti-TNFa, en 15 pacientes (10%) se indicó la cirugía y en 3 pacientes (2%) la enteroRM indujo a cambiar de terapia combinada a monoterapia. La enteroRM en la sospecha de EC influyó menos en las decisiones clínicas que cuando se indicaba por seguimiento (p < 0,05). Conclusiones: la enteroRM ayudó a decidir en más de la mitad de los pacientes, en especial en el seguimiento clínico para el manejo de las terapias biológicas y la indicación de la cirugía. Fue menos útil cuando la indicación fue la sospecha de EC(AU)

Objective: to describe the experience at two tertiary centres during the first year of use of magnetic resonance enterography (MRE) for the management of Crohn’s disease (CD): indications and influence of the technique in clinical decision making. Material and method: retrospective descriptive study in which patients who underwent MRE were included consecutively. Epidemiological and clinical data were collected from the patients, as well as the indication for the study and how it influenced clinical decision making in the 10 days following the radiological study. Results: 24 MREs were performed in suspected CD and 126 known CD; partial bowel obstruction in 53 patients (42%), monitoring of medical treatment in 34 (27%), due to incomplete ileocolonoscopy in 16 (13%), extension study of the small intestine in 15 (12%) and suspected complicated CD in 8 patients (6%). The MRE influenced in a change in treatment in 83 (55.3%) patients: 16 (10.7%) started with immunosuppressants, 41 (27.3%) with anti- TNFa were started on or switched, 15 (10%) were ordered surgery and in 3 (2%) changed from combined therapy to monotherapy. The MRE had less influence on clinical decision making in the group in which the indication was suspected CD (p < 0.05). Conclusions: the use of MRE helped on decision making in more than half of patients, especially with regards to decisions related to the use of biological therapies and the indication for surgery. MRE was less useful in suspected CD patients(AU)

Structural organization of mammalian prions as probed by limited proteolysis.

Elucidation of the structure of PrP(Sc) continues to be one major challenge in prion research. The mechanism of propagation of these infectious agents will not be understood until their structure is solved. Given that high resolution techniques such as NMR or X-ray crystallography cannot be used, a number of lower resolution analytical approaches have been attempted. Thus, limited proteolysis has been successfully used to pinpoint flexible regions within prion multimers (PrP(Sc)). However, the presence of covalently attached sugar antennae and glycosylphosphatidylinositol (GPI) moieties makes mass spectrometry-based analysis impractical. In order to surmount these difficulties we analyzed PrP(Sc) from transgenic mice expressing prion protein (PrP) lacking the GPI membrane anchor. Such animals produce prions that are devoid of the GPI anchor and sugar antennae, and, thereby, permit the detection and location of flexible, proteinase K (PK) susceptible regions by Western blot and mass spectrometry-based analysis. GPI-less PrP(Sc) samples were digested with PK. PK-resistant peptides were identified, and found to correspond to molecules cleaved at positions 81, 85, 89, 116, 118, 133, 134, 141, 152, 153, 162, 169 and 179. The first 10 peptides (to position 153), match very well with PK cleavage sites we previously identified in wild type PrP(Sc). These results reinforce the hypothesis that the structure of PrP(Sc) consists of a series of highly PK-resistant ß-sheet strands connected by short flexible PK-sensitive loops and turns. A sizeable C-terminal stretch of PrP(Sc) is highly resistant to PK and therefore perhaps also contains ß-sheet secondary structure.

PK-sensitive PrP is infectious and shares basic structural features with PK-resistant PrP.

One of the main characteristics of the transmissible isoform of the prion protein (PrP(Sc)) is its partial resistance to proteinase K (PK) digestion. Diagnosis of prion disease typically relies upon immunodetection of PK-digested PrP(Sc) following Western blot or ELISA. More recently, researchers determined that there is a sizeable fraction of PrP(Sc) that is sensitive to PK hydrolysis (sPrP(Sc)). Our group has previously reported a method to isolate this fraction by centrifugation and showed that it has protein misfolding cyclic amplification (PMCA) converting activity. We compared the infectivity of the sPrP(Sc) versus the PK-resistant (rPrP(Sc)) fractions of PrP(Sc) and analyzed the biochemical characteristics of these fractions under conditions of limited proteolysis. Our results show that sPrP(Sc) and rPrP(Sc) fractions have comparable degrees of infectivity and that although they contain different sized multimers, these multimers share similar structural properties. Furthermore, the PK-sensitive fractions of two hamster strains, 263K and Drowsy (Dy), showed strain-dependent differences in the ratios of the sPrP(Sc) to the rPrP(Sc) forms of PrP(Sc). Although the sPrP(Sc) and rPrP(Sc) fractions have different resistance to PK-digestion, and have previously been shown to sediment differently, and have a different distribution of multimers, they share a common structure and phenotype.

Using of magnetic resonance enterography in the management of Crohn's disease of the small intestine: first year of experience.

OBJECTIVE: to describe the experience at two tertiary centres during the first year of use of magnetic resonance enterography (MRE) for the management of Crohn's disease (CD): indications and influence of the technique in clinical decision making. MATERIALS AND METHODS: retrospective descriptive study in which patients who underwent MRE were included consecutively. Epidemiological and clinical data were collected from the patients, as well as the indication for the study and how it influenced clinical decision making in the 10 days following the radiological study. RESULTS: 24 MREs were performed in suspected CD and 126 known CD; partial bowel obstruction in 53 patients (42%), monitoring of medical treatment in 34 (27%), due to incomplete ileocolonoscopy in 16 (13%), extension study of the small intestine in 15 (12%) and suspected complicated CD in 8 patients (6%). The MRE influenced in a change in treatment in 83 (55.3%) patients: 16 (10.7%) started with immunosuppressants, 41 (27.3%) with anti-TNFα were started on or switched, 15 (10%) were ordered surgery and in 3 (2%) changed from combined therapy to monotherapy. The MRE had less influence on clinical decision making in the group in which the indication was suspected CD (p < 0.05). CONCLUSIONS: the use of MRE helped on decision making in more than half of patients, especially with regards to decisions related to the use of biological therapies and the indication for surgery. MRE was less useful in suspected CD patients.

The role of magnetic resonance imaging in oncology.

Conventional diagnostic magnetic resonance imaging (MRI) techniques have focused on improving the spatial resolution and image acquisition speed (whole-body MRI) or on new contrast agents. Most advances in MRI go beyond morphologic study to obtain functional and structural information in vivo about different physiological processes of tumor microenvironment, such as oxygenation levels, cellular proliferation, or tumor vascularization through MRI analysis of some characteristics: angiogenesis (perfusion MRI), metabolism (MRI spectroscopy), cellularity (diffusion-weighted MRI), lymph node function, or hypoxia [blood-oxygen-level-dependent (BOLD) MRI]. We discuss the contributions of different MRI techniques than must be integrated in oncologic patients to substantially advance tumor detection and characterization risk stratification, prognosis, predicting and monitoring response to treatment, and development of new drugs.

Increased oxidation, glycoxidation, and lipoxidation of brain proteins in prion disease.

The basic molecular underpinnings of the pathological changes that unfold in prion disease remain elusive. A key role of increased oxidative stress has been hypothesized. Given the transient nature of most intermediate molecules implicated, increased oxidative stress is better assessed by quantitating the damage it causes to macromolecules. We used mass spectrometry-based methods to measure specific products of protein oxidation, glycoxidation, and lipoxidation in brains from patients suffering from Creutzfeldt-Jakob disease and Syrian hamsters affected by scrapie. In both cases, increased amounts of glutamic and aminoadipic semialdehydes, products of metal-catalyzed oxidation, malondialdehydelysine (a product of lipoxidation), N-epsilon-carboxyethyllysine (a product of glycoxidation), and N-epsilon-carboxymethyllysine (generated by lipoxidation and glycoxidation) were measured. PrP(Sc), the infectious isoform of the prion protein that accumulates in prion disease, was itself shown to be a target of increased oxidative modification. These changes were accompanied by alterations in fatty acid composition and increased phosphorylation of ERK(1/2) and p38, protein kinases known to respond to increased flows of ROS. These data support an important role of oxidative damage in the pathology of prion disease.

Scrapie prion protein structural constraints obtained by limited proteolysis and mass spectrometry.

Elucidation of the structure of scrapie prion protein (PrP(Sc)), essential to understand the molecular mechanism of prion transmission, continues to be one of the major challenges in prion research and is hampered by the insolubility and polymeric character of PrP(Sc). Limited proteolysis is a useful tool to obtain insight on structural features of proteins: proteolytic enzymes cleave proteins more readily at exposed sites, preferentially within loops, and rarely in beta-strands. We treated PrP(Sc) isolated from brains of hamsters infected with 263K and drowsy prions with varying concentrations of proteinase K (PK). After PK deactivation, PrP(Sc) was denatured, reduced, and cleaved at Cys179 with 2-nitro-5-thiocyanatobenzoic acid. Fragments were analyzed by nano-HPLC/mass spectrometry and matrix-assisted laser desorption/ionization. Besides the known cleavages at positions 90, 86, and 92 for 263K prions and at positions 86, 90, 92, 98, and 101 for drowsy prions, our data clearly demonstrate the existence of additional cleavage sites at more internal positions, including 117, 119, 135, 139, 142, and 154 in both strains. PK concentration dependence analysis and limited proteolysis after partial unfolding of PrP(Sc) confirmed that only the mentioned cleavage sites at the N-terminal side of the PrP(Sc) are susceptible to PK. Our results indicate that besides the "classic" amino-terminal PK cleavage points, PrP(Sc) contains, in its middle core, regions that show some degree of susceptibility to proteases and must therefore correspond to subdomains with some degree of structural flexibility, interspersed with stretches of amino acids of high resistance to proteases. These results are compatible with a structure consisting of short beta-sheet stretches connected by loops and turns.

Fibrillar prion peptide PrP(106-126) treatment induces Dab1 phosphorylation and impairs APP processing and Abeta production in cortical neurons.

Alzheimer's disease and prion diseases (e.g., Creutzfeldt-Jakob disease) display profound neural lesions associated with aberrant protein processing and extracellular amyloid deposits. However, the intracellular events in prion diseases and their relation with the processing of the amyloid precursor protein (APP) and beta-amyloid generation are unknown. The adaptor protein Dab1 may regulate intracellular trafficking and secretase-mediated proteolysis in APP processing. However, a putative relationship between prion diseases and Dab1/APP interactions is lacking. Thus, we examined, in inoculated animals, whether Dab1 and APP processing are targets of the intracellular events triggered by extracellular exposure to PrP(106-126) peptide. Our in vitro results indicate that PrP(106-126) peptide induces tyrosine phosphorylation of Dab1 by activated members of the Src family of tyrosine kinases (SFK), which implies further Dab1 degradation. We also corroborate these results in Dab1 protein levels in prion-inoculated hamsters. Finally, we show that fibrillar prion peptides have a dual effect on APP processing and beta-amyloid production. First, they block APP trafficking at the cell membrane, thus decreasing beta-amyloid production. In parallel, they reduce Dab1 levels, which also alter APP processing. Lastly, neuronal cultures from Dab1-deficient mice showed severe impairment of APP processing with reduced sAPP secretion and A beta production after prion peptide incubation. Taken together, these data indicate a link between intracellular events induced by exposure to extracellular fibrillar peptide or PrP(res), and APP processing and implicate Dab1 in this link.

Isolation and characterization of a proteinase K-sensitive PrPSc fraction.

Recent studies have shown that a sizable fraction of PrPSc present in prion-infected tissues is, contrary to previous conceptions, sensitive to digestion by proteinase K (PK). This finding has important implications in the context of diagnosis of prion disease, as PK has been extensively used in attempts to distinguish between PrPSc and PrPC. Even more importantly, PK-sensitive PrPSc (sPrPSc) might be essential to understand the process of conversion and aggregation of PrPC leading to infectivity. We have isolated a fraction of sPrPSc. This material was obtained by differential centrifugation at an intermediate speed of Syrian hamster PrPSc obtained through a conventional procedure based on ultracentrifugation in the presence of detergents. PK-sensitive PrPSc is completely degraded under standard conditions (50 mug/mL of proteinase K at 37 degrees C for 1 h) and can also be digested with trypsin. Centrifugation in a sucrose gradient showed sPrPSc to correspond to the lower molecular weight fractions of the continuous range of oligomers that constitute PrPSc. PK-sensitive PrPSc has the ability to convert PrPC into protease-resistant PrPSc, as assessed by the protein misfolding cyclic amplification assay (PMCA). Limited proteolysis of sPrPSc using trypsin allows for identification of regions that are particularly susceptible to digestion, i.e., are partially exposed and flexible; we have identified as such the regions around residues K110, R136, R151, K220, and R229. PK-sensitive PrPSc isolates should prove useful for structural studies to help understand fundamental issues of the molecular biology of PrPSc and in the quest to design tests to detect preclinical prion disease.

Cardiac magnetic resonance imaging in the diagnosis of myocarditis mimicking myocardial infarction.

Cardiac Magnetic Resonance (CMR) imaging has recently become a very useful tool in the diagnosis of myocarditis. We describe a patient in whom acute myocarditis was presented as an acute myocardial infarction and had an atypical course with rapid normalization of ECG abnormalities. In this case CMR imaging was essential to confirm the diagnosis of myocarditis.

Long-term oral tacrolimus therapy in refractory to infliximab fistulizing Crohn's disease: a pilot study.

AIMS: To evaluate efficacy and safety of oral tacrolimus in cases of fistulizing Crohn's disease (FCD), which is refractory to conventional therapy including infliximab. METHODS: Patients with fistulas, previously and unsuccessfully treated with all conventional therapy (i.e., antibiotics, azathioprine, or 6-mercaptopurine and infliximab), were enrolled in a prospective, uncontrolled, open-label study of long-term treatment with oral tacrolimus (0.05 mg/kg every 12 h). The evaluation of the clinical response was complemented by use of the perianal Crohn's disease activity index (PCDAI) and magnetic resonance imaging-based score (MRS) with determined periodicity. RESULTS: Ten patients were included in the study (enterocutaneous fistula, 3 patients; perianal fistula, 4 patients; rectovaginal fistula, 3 patients) with 6 to 24 months of follow-up. Five patients were steroid-dependent, and 4 patients needed maintenance treatment with immunosuppressant agents. Four patients (40%) achieved complete clinical responses, which were verified by PCDAI and MRS. Five patients (50%) achieved partial responses (i.e., important decreases in fistula drainage, size, discomfort, and PCDAI/MRS values). Decreases in both the PCDAI and MRS were statistically significant (P < 0.05). All steroid-dependent patients stopped therapy with prednisone, and concomitant immunosuppressive therapy was tapered. The response was maintained, and no new flare-up of the disease was observed. Only mild adverse events were detected (1 patient withdrew from treatment due to headache), and no case of nephrotoxicity or diabetes was detected. One patient had received no benefit from therapy after 6 months. CONCLUSIONS: Oral tacrolimus could be an effective and safe treatment for patients with FCD, even if there has been no response to infliximab treatment. Randomized studies are needed to compare oral tacrolimus with infliximab in terms of efficacy, safety, and costs.

[Right atrial pheochromocytoma]. / Feocromocitoma de aurícula derecha.

Pheochromocytoma is a catecholamine-producing tumor and a rare cause of hypertension. Most cases are intra-adrenal and intrapericardial pheochromocytomas are extremely uncommon. We report the case of a 46-year-old woman with a 1-year history of hypertension, in which a right atrial pheochromocytoma was detected after a hypertensive crisis. 131I-metaiodobenzylguanidine scintigraphy and magnetic resonance imaging established the diagnosis. The tumor was successfully resected using cardiopulmonary bypass and the right atrium was reconstructed using bovine pericardium.