The dentate nucleus in Friedreich’s ataxia: the role of iron-responsive proteins

Frataxin deficiency in Friedreich’s ataxia (FRDA) causes cardiac, endocrine, and nervous system manifestations. Frataxin is a mitochondrial protein, and adequate amounts are essential for cellular iron homeostasis. The main histological lesion in the brain of FRDA patients is neuronal atrophy and a peculiar proliferation of synaptic terminals in the dentate nucleus termed grumose degeneration. This cerebellar nucleus may be especially susceptible to FRDA because it contains abundant iron. We examined total iron and selected iron-responsive proteins in the dentate nucleus of nine patients with FRDA and nine normal controls by biochemical and microscopic techniques. Total iron (1.53 ± 0.53 μmol/g wet weight) and ferritin (206.9 ± 46.6 μg/g wet weight) in FRDA did not significantly differ from normal controls (iron: 1.78 ± 0.88 μmol/g; ferritin: 210.9 ± 9.0 μg/g) but Western blots exhibited a shift to light ferritin subunits. Immunocytochemistry of the dentate nucleus revealed loss of juxtaneuronal ferritin-containing oligodendroglia and prominent ferritin immunoreactivity in microglia and astrocytes. Mitochondrial ferritin was not detectable by immunocytochemistry. Stains for the divalent metal transporter 1 confirmed neuronal loss while endothelial cells reacting with antibodies to transferrin receptor 1 protein showed crowding of blood vessels due to collapse of the normal neuropil. Regions of grumose degeneration were strongly reactive for ferroportin. Purkinje cell bodies, their dendrites and axons, were also ferroportin-positive, and it is likely that grumose degeneration is the morphological manifestation of mitochondrial iron dysmetabolism in the terminals of corticonuclear fibers. Neuronal loss in the dentate nucleus is the likely result of trans-synaptic degeneration.     

Successful management of severe unremitting chylothorax after thoraci trauma

Post-traumatic chylothorax needs surgical approach when conservative treatment is not successful to reduce chyle leakage. Thoracic duct ligation requires thoracoscopic or thoracotomic access. The authors report on a surgical thoracotomic approach to a severe and unremitting thoracic duct lesion after IX and X ribs and vertebral fractures.     

Endoscopic ultrasonography coupled with fine needle aspiration biopsy of intraductal papillary-mucinous tumours of the pancreas. Tool or gadget? A report of three cases

We report three cases of intraductal papillary-mucinous tumour of the pancreas, occurring over a brief period in our surgical unit. Symptoms were aspecific in two cases, while only one of the patients presented a picture of acute pancreatitis. Preoperative investigations included ultrasonography, abdominal CT-scan and endoscopic ultrasonography (EUS) with guided fine needle aspiration biopsy (EUS-FNAB) of the cyst. EUS furnished invaluable data about the neoplasm and pancreatic duct morphology, while EUS-FNAB was crucial in revealing cytological features highly suggestive of intraductal papillary-mucinous tumour. All three patients underwent surgical resection, (two pylorus-preserving pancreatico-duodenectomies and one total pancreatectomy). The histological features of the resected specimen confirmed the preoperative EUS-FNAB diagnosis. After a medium-term follow-up, patients have been free of abdominal symptoms with no evidence of recurrence at CT-scan. In the present study we analyse the feasibility and effectiveness of EUS and EUS-FNAB in diagnosing intraductal papillary-mucinous tumours and in predicting their malignancy.     

MHC class II compartment subtypes: structure and function

Reports from the past couple of years point to an emerging association of the biogenesis, composition and ultrastructural morphology of MHC class II compartments (MIICs) with their functions in antigen processing and loading. Growth factors and cytokines involved in dendritic cell maturation have been shown to regulate MIIC biogenesis, and the MHC-class-II-associated invariant chain chaperone has been reported to regulate endosomal morphology and vacuolation. Differences among ultrastructurally distinct MIICs have begun to be appreciated with regard to variation in antigen loading capacity and to polarization of MHC class II conformational variants among different compartments. Finally, the MIIC ultrastructure organizes the mechanism of MHC class II surface trafficking. Together, these findings begin to shed light on the connection between MIIC protein content, MIIC morphology and MHC class II-related antigen processing.     

Improving the Procedure for Detection of Intrahepatic Transplanted Islets by Magnetic Resonance Imaging

Islet transplantation is an effective therapy for restoring normoglycemia in type-1 diabetes, but long-term islet graft function is achieved only in a minority of cases. Noninvasive magnetic resonance imaging of pancreatic islets is an attractive option for "real-time" monitoring of graft evolution. So far, previous studies have been performed in the absence of a standardized labeling procedure and, besides a feasibility study in patients, the effectiveness and safety of various labeling approaches were tested only with high field magnets (4.7 T). In this study, we addressed: (a) standardization of a labeling procedure for human islets with clinically-approved contrast agent Endorem^®, (b) safety aspects of labeling related to inflammation and (c) quality of imaging both at 7 T and 1.5 T. We have highlighted that the ratio of Endorem^®/islet is crucial for reproducible labeling, with a ratio of 2.24 ug/IEQ, allowing successful in vivo imaging both with 1.5 T and 7.0 T magnets up to 143 days after intrahepatic transplant. With this standardized labeling procedure, labeled islets are neither inflamed nor more susceptible to inflammatory insults than unlabeled ones. This report represents an important contribution towards the development of a standardized and safe clinical protocol for the noninvasive imaging of transplanted islets in humans.     

ELISA reveals a difference in the structure of substantia nigra ferritin in Parkinson's disease and incidental Lewy body compared to control

Iron released from ferritin may trigger oxidative stress leading to progressive neurodegeneration of substantia nigra resulting in Parkinson's disease (PD). Change in the structure of ferritin may allow an easier efflux of iron. We compared with the use of ELISA the structure of ferritin (concentrations of H and L ferritins) in substantia nigra (SN) in ten cases of PD, six of incidental Lewy body (ILB) cases and 20 controls. SN concentration of L ferritin in ILB (50.6+/-11.5 ng/mg) and in PD (52.5+/-26.0) was lower than in control (97.9+/-54.9). H ferritin in PD (534.2+/-223.1) was higher than in ILB (336.9+/-87.7) and control (374.8+/-169.3). The decrease of L ferritin in SN in PD and ILB may suggest that the whole process of neurodegeneration starts with a higher availability of free iron, which is released from the ferritin shell.     

Serum hepcidin levels and muscle iron proteins in humans injected with low‐ or high‐dose erythropoietin

Inhibition of hepcidin expression by erythropoietic signals is of great physiological importance; however, the inhibitory pathways remain poorly understood. To investigate (i) the direct effect of erythropoietin (Epo) and (ii) the contribution of putative mediators on hepcidin repression, healthy volunteers were injected with a single dose of Epo, either low (63 IU/kg, n = 8) or high (400 IU/kg, n = 6). Low‐dose Epo provoked hepcidin down‐modulation within 24 h; the effect was not immediate as hepcidin circadian variations were still present following injection. High‐dose Epo induced no additional effect on the hepcidin response, that is hepcidin diurnal fluctuations were not abolished in spite of extremely high Epo levels. We did not find significant changes in putative mediators of hepcidin repression, such as transferrin saturation, soluble transferrin receptor, or growth differentiation factor 15. Furthermore, the potential hepcidin inhibitor, soluble hemojuvelin, was found unaltered by Epo stimulation. This finding was consistent with the absence of signs of iron deficiency observed at the level of skeletal muscle tissue. Our data suggest that hepcidin repression by erythropoietic signals in humans may not be controlled directly by Epo, but mediated by a still undefined factor.