1. Department of Internal Medicine (Digestive Diseases), Yale School of Medicine, New Haven, CT 06511, USA
2. Department of Neuroscience and Rehabilitation, University of Ferrara, 44124 Ferrara, Italy
3. Interdepartmental Research Center for Multiple Sclerosis and Other Inflammatory and Degenerative Disorders of the Nervous System, University of Ferrara, 44124 Ferrara, Italy
4. Department of Clinical, Medical and Surgical Sciences, University of Trieste, 34149 Trieste, Italy