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Analysis of Acid Sphingomyelinase Activity in Dried Blood Spots Using Tandem Mass Spectrometry
Elisa Legnini,Joe J. Orsini,Adolf Mühl,Britt Johnson,Angela Dajnoki,Olaf A Bodamer 대한진단검사의학회 2012 Annals of Laboratory Medicine Vol.32 No.5
Background: Niemann Pick disease (NP) is a rare, lysosomal storage disorder due to deficiency of the intra-lysosomal enzyme acid sphingomyelinase (ASM) resulting in intracellular accumulation of sphingomyelin. We evaluated a tandem mass spectrometry (MS/MS)method to analyze ASM activity in dried blood spots (DBS) that may be suitable for laboratory diagnosis of NP including high throughput screening of at-risk populations and potentially for newborn screening. Methods: ASM activity was measured in 3.2 mm punches from DBS. The eluate was incubated with the ASM substrate (N-Hexanoyl-D-erythro-sphingosylphosphorylcholine [C6- sphingomyelin (C29H59N2O6P)]) and an internal standard (N-butyroyl-D-erythro-sphingosine [C4-ceramide (C22H43NO3)]). ASM product and IS were analyzed using MS/MS in multiple reaction monitoring mode for transitions m/z 370.6>264.3 (ASM internal standard) and m/z 398.6>264.3 (ASM product). Results: ASM activities were stable for up to 2 months at or below 4˚C. Position of the punch in the DBS and/or hematocrit of the DBS had a limited effect on ASM activities. Both intraand inter-assay variability were below 10%. There was no carry-over. The median ASM activity in 2,085 newborn infants was 9.5 μmol/h/L (mean 10.6) with a SD of 5.06 μmol/h/L. Six of 2,085 (0.3%) infants were found to have ASM activities below the cut-off of 2.5 μmol/h/L. ASM activities were below the cut-off level in all 10 previously diagnosed cases with NP (range: 0.16 to 2.08 μmol/h/L). Conclusions: This MS/MS method for the measurement of ASM activity in DBS is robust and suitable for laboratory diagnosis of NP. Background: Niemann Pick disease (NP) is a rare, lysosomal storage disorder due to deficiency of the intra-lysosomal enzyme acid sphingomyelinase (ASM) resulting in intracellular accumulation of sphingomyelin. We evaluated a tandem mass spectrometry (MS/MS)method to analyze ASM activity in dried blood spots (DBS) that may be suitable for laboratory diagnosis of NP including high throughput screening of at-risk populations and potentially for newborn screening. Methods: ASM activity was measured in 3.2 mm punches from DBS. The eluate was incubated with the ASM substrate (N-Hexanoyl-D-erythro-sphingosylphosphorylcholine [C6- sphingomyelin (C29H59N2O6P)]) and an internal standard (N-butyroyl-D-erythro-sphingosine [C4-ceramide (C22H43NO3)]). ASM product and IS were analyzed using MS/MS in multiple reaction monitoring mode for transitions m/z 370.6>264.3 (ASM internal standard) and m/z 398.6>264.3 (ASM product). Results: ASM activities were stable for up to 2 months at or below 4˚C. Position of the punch in the DBS and/or hematocrit of the DBS had a limited effect on ASM activities. Both intraand inter-assay variability were below 10%. There was no carry-over. The median ASM activity in 2,085 newborn infants was 9.5 μmol/h/L (mean 10.6) with a SD of 5.06 μmol/h/L. Six of 2,085 (0.3%) infants were found to have ASM activities below the cut-off of 2.5 μmol/h/L. ASM activities were below the cut-off level in all 10 previously diagnosed cases with NP (range: 0.16 to 2.08 μmol/h/L). Conclusions: This MS/MS method for the measurement of ASM activity in DBS is robust and suitable for laboratory diagnosis of NP.
Joe M. Das,Krishnakumar Kesavapisharady,Saravanan Sadasivam,Suresh Narayanan Nair 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.4
Study Design: Retrospective cohort study. Purpose: To examine the clinical profile and surgical complications in patients with spinal hemangioblastomas and to evaluate the long-term outcome in them. Overview of Literature: Although considered to be histologically benign, hemangioblastomas may cause significant neurological deficits. The proportion of spinal hemangioblastomas associated with von Hippel–Lindau (VHL) disease has been estimated be 13%–59%. Preoperative neurological function correlates with postoperative neurological status. Studies have shown no difference in outcomes between sporadic and VHL-associated spinal hemangioblastomas. Methods: This retrospective study included 14 consecutive patients treated for spinal hemangioblastomas at our institute between January 2000 and June 2013. The mean follow-up period was 5 years. Magnetic resonance imaging of the complete neuraxis was performed in all cases, and preoperative embolization was performed in two cases. Results: In total, 14 patients underwent 18 surgeries, of which 15 were for spinal hemangioblastomas. Of all the patients, 86% had motor weakness and 79% presented with sensory disturbances. Preoperative McCormick functional grades were grade I in 7 (50%), grade II in 3 (21%), and grade III in 4 (29%) patients; 50% patients were diagnosed with VHL disease. All patients underwent complete resection of the tumor. Eight patients experienced deterioration in their neurological status in the immediate postoperative period; among them, five had gradual improvement. At 5-year follow-up, 11 (78.57%) patients showed good functional outcomes. Conclusions: Microsurgical excision of spinal hemangioblastomas can cause postoperative morbidity, mainly in the form of neurological deterioration. Almost half of our patients had deterioration in the McCormick grade in the immediate postoperative period. However, a complete microsurgical excision can result in good long-term functional outcomes, as most of the immediate postoperative neurological deterioration in our patients was reversible. There was no difference in the long-term functional outcomes between sporadic and VHL-associated spinal hemangioblastomas.
Joe M. Das,Anilkumar Peethambaran 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.1
Schwannomas are the most common intradural extramedullary tumors of the spine. They usually occupy a posterolateral or lateral position in relation to the cord. The ventral midline is a very rare location for the origin of a spinal schwannoma. A giant one in such a location causes technical difficulties in excision. Here, we present a giant cervical spinal schwannoma, located ventral to the cord, in a 38-year-old lady who presented with features of myelopathy and bladder involvement. Magnetic resonance imaging was suggestive of an intradural extramedullary lesion extending from cervico-medullary junction to the third dorsal vertebral level with severe cord compression. The same was excised totally via a posterior approach after midline suboccipital craniectomy and C2–C6 laminoplasty. Postoperatively, she made a good recovery and was ambulant without support. Postoperative magnetic resonance imaging showed complete excision of the tumor. Histopathology was suggestive of schwannoma.