This phenomenon was observed repeatedly during diafiltration of different therapeutic monoclonal antibodies in which the concentrations of histidine and either sorbitol check details or sucrose (depending on which was chosen for the diafiltration buffer) in the retentate were lower than in the diafiltration buffer. Experimental studies and theoretical analyses of the ultrafiltration/diafiltration (UF/DF) step were carried out to determine the primary causes of the phenomenon and to develop a mathematical model capable of predicting retentate excipient concentrations. The analyses showed that retentate histidine concentration was low primarily

because of repulsive charge interactions between positively-charged histidine molecules and positively-charged

protein molecules, and that volume exclusion effects were secondary for like-charged molecules. The positively-charged protein molecules PF-00299804 supplier generate an electrical potential that cause all uneven distribution of charged histidine molecules. This interaction was used to construct a mathematical model based on the Poisson-Boltzmann equation. The model successfully predicted the final histidine concentration in the diafiltered product (retentate) from the UF/DF development and production runs, with good agreement across a wide range of protein and histidine concentrations for four therapeutic monoclonal antibodies. The concentrations of uncharged excipients (sorbitol or sucrose) were also successfully predicted using previously established models, with volume exclusion identified as the primary cause of differences in uncharged excipient concentrations in the retentate and diafiltration buffer. (C) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 25: 964-972,2009″
“Background: Multiple system atrophy (MSA) rarely begins before the age of 40 and detailed descriptions of young-onset MSA are lacking.\n\nMethods: Among 455 patients

included in our MSA cohort, four developed disease before the age of 40. We reviewed selleck chemical the medical records of these patients.\n\nResults: Case 1 and 2 presented with cerebellar symptoms. Case 1 had clinical features and a course typical of MSA. Case 2 had a rapid course and died 3 years after onset. Case 3 and Case 4 presented with levodoparesponsive parkinsonism. Both developed motor fluctuations and peak-dose limb dyskinesias. Subthalamic deep brain stimulation (DBS) resulted in some improvements in motor symptoms, but they became totally dependent within a few years.\n\nDiscussion: Young-onset MSA is rare but does exist. Young-onset MSA with predominant parkinsonism may closely resemble Parkinson disease at onset and is likely to develop motor complications. Attention should be given to the possibility of young-onset MSA in selecting DBS candidates. (C) 2012 Elsevier B.V. All rights reserved.”
“Ocular neuromyotonia refers to paroxysmal involuntary contraction of one or more ocular muscles resulting in paroxysmal diplopia and strabismus.