ABSTRACT
Zinc-sensitive fluorescent probes have become increasingly important in the investigation of the cellular roles of zinc. There is, however, little information on how the other transition metals in cells may influence the measurement of zinc. We have characterized in vitro the interaction of the nominal zinc indicators FluoZin-3 and Newport Green with all the cationic transition metals found within cells, Cr, Mn, Fe, Co, and Cu, as well as Ni and Cd, by measuring their dissociation constants. In addition, we have shown how FluoZin-3 can be used to quantify the concentration of copper in a cell-free assay and report that the fluorescence of Newport Green is boosted by both Cu(I) and Fe(II). Furthermore, we have introduced diagnostics for detecting the interference of metals other than zinc with its measurement within cells.
Subject(s)
Fluorescent Dyes/chemistry , Polycyclic Compounds/chemistry , Transition Elements/chemistry , Zinc/chemistry , Cadmium/chemistry , Cobalt/chemistry , Copper/chemistry , Kinetics , Nickel/chemistry , Oxidation-ReductionABSTRACT
There has been some dispute in the literature as to the sensitivity of the zinc indicator FluoZin-3 to calcium, with suggestions that physiological levels of calcium and magnesium effectively occlude the response of the probe to zinc. In this communication we demonstrate that calcium concentrations as high as 10 mM do not prevent FluoZin-3 from detecting zinc elevations as low as 100 pM. Moreover, the inclusion of a few microM Ca-EDTA does not prevent FluoZin-3 from responding to increases in zinc concentration but does extend the dynamic range of the probe by reducing contaminating zinc levels and allowing the probe to respond to multiple zinc additions. In addition, we have derived a mathematical model to account for the kinetics of FluoZin-3 response to zinc in the presence of an additional zinc and calcium chelator.
Subject(s)
Calcium/metabolism , Edetic Acid/metabolism , Magnesium/metabolism , Polycyclic Compounds/metabolism , Zinc/analysis , Spectrometry, FluorescenceABSTRACT
OBJECTIVE: To better understand the presentation, management, and outcome of syringobulbia in the pediatric age group. METHODS: The University of Iowa pediatric neurosurgery database was searched for patients under the age of 18 with a diagnosis of syringobulbia. The patients' records were retrospectively reviewed for demographic data, chief complaint and presenting symptoms, neurological and radiographic findings, treatment, outcome, and complications. Children with open neural tube defects and Chiari II malformations were excluded. RESULTS: Six pediatric patients were identified as meeting inclusion criteria. The average age at time of surgery was 14.8 years. The chief complaints were vision impairment in three children and numbness, gait instability, and headache worsened with Valsalva in one patient each. Other prominent symptoms included sleep apnea and weakness. All patients showed at least one cranial nerve dysfunction. Radiographs revealed hindbrain herniation and associated syringomyelia in all cases. Two patients had scoliosis. Treatment was posterior fossa decompression with cerebellar tonsillar shrinkage, opening of foramen of Magendie, and duraplasty. Two patients also required concomitant ventral decompression. The cavity of syringobulbia communicated with syringomyelia and the fourth ventricle in most children but was distinct from the fourth ventricle. Two patients received fourth ventricle to subarachnoid shunts. Follow-up averaged 3.2 years, and all patients clinically improved after surgery. Magnetic resonance imaging documented resolution of syringobulbia in all cases, with syringomyelia improving in all cases. There was no permanent morbidity or mortality in the series. CONCLUSION: Syringobulbia is strongly associated with Chiari malformation and syringomyelia, and patients often present because of cranial nerve palsies. Posterior fossa decompression is a safe and effective treatment.
