ABSTRACT
BACKGROUND: Decreased galactocerebrosidase (GALC) enzyme activity is causative for Krabbe disease, a lysosomal storage disorder with devastating neurodegenerative consequences. Quantitative fluorimetric assays for GALC activity in isolated blood and skin cells have been described; however, no such assay has been described using dried blood spot (DBS) specimens. METHODS: GALC enzyme activity was measured quantitatively using fluorescence from a novel glycosidic substrate: carboxy derived from 6-hexadecanoylamino-4-methylumbelliferone. GALC activity was demonstrated on newborn DBS specimens, known Krabbe disease patient specimens, proficiency testing and quality control samples. RESULTS: We present data on characterization of the novel substrate and assay, including pH optimization and enzyme kinetics using a fluorimetric profile. Single and multi-day precision analyses revealed tight analytical measurements with %CV ranging from 5.2% to 14.1%. GALC enzyme activity was linear over the range of 0.31 - 12.04 µmol/l/h with a limit of detection of 0.066 µmol/l/h. Our results with this assay show a clear discrimination between GALC activities in samples from Krabbe disease patients versus presumed normal newborn samples. CONCLUSIONS: A fluorimetric assay for GALC enzyme activity measurement on dried blood spot specimens is feasible. Improvements to the assay including novel substrate design, increased substrate concentration and removal of sodium chloride maximize the specificity of the assay and minimize interference from ß-galactosidase.
ABSTRACT
This paper reports the first year's experience of a consultative, interdisciplinary, integrated palliative medicine program in a community hospital system. Prospective data collection was performed on 308 consecutive consultations. A computer database was developed and used to analyze demographics, reason for consultation, complexity of medical problems, current medications and allergies, physical suffering, spiritual concerns, personal and family concerns, consult recommendations, and mortality. In addition, data were collected on patient rating of the severity of physical symptoms, pain, spiritual suffering, and personal and family suffering; this data also was analyzed using the database. Cancer was the most frequent diagnosis (34 percent) and pain the most common reason for consultation (43 percent). Population medians were identified as follows: five (range, 1 to 10) acute medical problems; three (range, 1 to 10) chronic medical problems; and one (range, 0 to 10) medication allergy/intolerance. Patients were taking a median of 10 (range, 0 to 29) medications, including a median of two analgesics. Eighty percent could communicate concerning physical symptoms and had a median of two (range, 0 to 7) bothersome symptoms, with pain the most frequent. Fifty percent or fewer could rate physical suffering, pain, hope, spiritual suffering, or personal/family suffering using a 0 to 10 scale at consultation. Individual patient ratings provided over time for physical suffering, pain, hope, spiritual suffering, and personal/family suffering were available for less than 25 percent. A median of eight recommendations was made for each consultation, with medication changes suggested for 84 percent. For those known to have died, the median survival from time of consultation to death was 11 days.
